WO2025169958A1 - Machining shape simulation device - Google Patents

Abstract

Provided is a vibration simulation device (1) for simulation of vibration between a tool (10) and a workpiece (20) in gear generation cutting, the vibration simulation device (1) comprising a shape defining unit (120) that defines a tool shape and a workpiece shape, an interference region calculation unit (130) that calculates an interference region between the tool (10) and the workpiece (20) during processing on the basis of the tool (10) and the relative movement trajectory of the workpiece (20), a cutting force calculation unit (140) that calculates a cutting force during removal of the interference region from the workpiece (20) by the tool (10), a movement characteristic defining unit (150) that defines relative movement characteristics or individual movement characteristics between the tool and workpiece, a vibration calculation unit (160) that calculates relative vibration between the tool and workpiece on the basis of the cutting force and the relative movement characteristics, a frequency analysis unit (191) that performs frequency analysis on the vibration calculation result or the cutting force calculation result, a vibration occurrence evaluation unit (192) that evaluates the state of occurrence of relative vibration on the basis of the frequency analysis result of the frequency analysis unit (191), and a vibration state display unit (193) that displays the evaluation result.

Description

Machining shape simulation device

The present invention relates to a machining shape simulation device.

The gear skiving method described in Patent Document 1 is known as a gear machining method. This gear skiving method uses a machining tool with multiple tool blades on its outer periphery, with the central axis of the machining tool at an angle to an axis parallel to the central axis of the workpiece, and while the workpiece and the machining tool are rotated synchronously, the machining tool is advanced in a straight line along the central axis of the workpiece to perform cutting.

Patent Document 2 describes a gear cutting simulation device for gear skiving. This gear cutting simulation device makes it possible to determine the amount of cutting force acting on which part of the cutting tool's blade. This can be used to determine cutting conditions such as the cutting depth and feed rate of the cutting tool, enabling the design of an appropriate gear cutting device.

JP 2012-45687 A Japanese Patent Application Laid-Open No. 2014-237185

In gear-generating cutting processes such as gear skiving, in addition to static behavior such as displacement caused by the average cutting load between the tool and workpiece at the cutting point and the relative static stiffness between the tool and workpiece, dynamic behavior caused by fluctuations in the cutting load between the tool and workpiece and the relative dynamic characteristics between the tool and workpiece, i.e., vibrations such as forced vibration and self-excited vibration, occur. However, conventional gear cutting simulations do not fully take such vibrations into account, which is one of the factors that causes a discrepancy between the actual cutting results and the predicted results from the simulation, reducing prediction accuracy. Therefore, to improve the prediction accuracy of the cutting results in gear-generating cutting processes, it is necessary to predict vibrations at the cutting point with high accuracy. However, to date, there has been no accurate prediction of such vibrations in gear-generating cutting processes, which poses a challenge to improving the prediction accuracy of gear-generating cutting processes.

Furthermore, even if the results of gear generating cutting are predicted, they cannot be used effectively unless they are properly displayed to the user. Therefore, there is room for improvement in the display of predicted results.

Furthermore, even if the machining results predicted with sufficient consideration given to vibration as described above satisfy the desired gear accuracy, if the cutting resistance generated by machining is concentrated in a very small area on the cutting edge of the machining tool, the cutting edge of the tool may be damaged, making machining based on that prediction impossible. Therefore, to determine whether the predicted machining results are possible, it is necessary to consider the cutting condition of the tool's cutting edge. However, conventional gear machining simulations do not provide an appropriate display of the predicted cutting condition results to the user, and the judgement of whether machining is possible is left to the expert's experience. Therefore, there is room for improvement in the display of the predicted cutting condition results, which are used to determine whether machining is possible.

This disclosure has been made in light of these circumstances, and aims to provide a machining shape simulation device that can predict vibrations at the machining point during gear-generating cutting with high accuracy, improves the display of prediction results, and makes it easy to determine whether machining is possible.

One aspect of the present disclosure is
1. A machined shape simulation device that simulates a machined shape of a gear based on relative vibration between a tool and a workpiece in gear-generating cutting, in which a cutting process is performed on a workpiece with a tool to generate a gear, comprising:
a shape defining unit that defines a tool shape and a workpiece shape based on analysis conditions including tool specifications, workpiece specifications, and machining conditions;
a cutting edge model storage unit that stores model data of a cutting edge shape in the tool shape;
an interference area calculation unit that calculates an interference area between the tool and the workpiece during gear generating cutting, based on the tool shape, the workpiece shape, and relative movement trajectories of the tool and the workpiece;
a cutting force calculation unit that calculates a cutting force when the tool removes the interference region from the workpiece;
a dynamic characteristic defining unit that defines relative dynamic characteristics or individual dynamic characteristics between the tool and the workpiece based on the analysis conditions;
a vibration calculation unit that calculates the relative vibration between the tool and the workpiece based on the cutting force and the relative dynamic characteristics;
a machining result prediction unit that predicts a machining result of the workpiece based on a vibration simulation result including the relative vibration repeatedly calculated by the interference region calculation unit, the cutting force calculation unit, and the vibration calculation unit;
a frequency analysis unit that performs frequency analysis on the calculation result of the vibration calculation unit or the calculation result of the cutting force calculation unit;
a vibration generation evaluation unit that evaluates a generation state of the relative vibration based on a frequency analysis result of the frequency analysis unit;
a vibration state display unit that displays the evaluation result of the vibration generation evaluation unit;
a cutting edge state extraction unit that extracts cutting edge state extraction data during machining in a plurality of evaluation regions of the cutting edge shape based on at least the calculation result of the interference region calculation unit;
an evaluation item input unit for inputting evaluation items in the cutting edge state extraction data;
a cutting edge state display unit that displays the evaluation items of the cutting edge state extraction data in the evaluation area together with the cutting edge shape;
The present invention relates to a machining shape simulation device comprising:

In one embodiment of the machining shape simulation device disclosed herein, first, the interference area between the tool and workpiece during gear-generating cutting is calculated based on the tool shape and workpiece shape specified based on the analysis conditions, and the relative movement trajectory between the tool and workpiece, and the cutting force required to remove the interference area is calculated. Then, the relative dynamic characteristics or individual dynamic characteristics between the tool and workpiece are specified based on the analysis conditions, and the relative vibration between the tool and workpiece is calculated based on the cutting force and the dynamic characteristics. This makes it possible to predict vibration at the machining point during gear-generating cutting with high accuracy.

Furthermore, the state of relative vibration occurrence is evaluated based on the calculation results of the vibration calculation unit or the cutting force calculation unit, based on the frequency analysis results of the frequency analysis unit, and the evaluation results are displayed. By displaying the evaluation results in this way, the display content of the prediction results has been improved so that the user can make effective use of them.

Furthermore, because gear generating cutting involves cutting curved tooth surfaces, the predicted results for the machined shape tend to be more complex than when machining flat surfaces, such as with an end mill, making it difficult for users to understand the results. However, as mentioned above, improvements have been made to the display of predicted results, allowing users to effectively utilize the predicted results for machined shapes and chatter vibrations in gear generating cutting, which cuts curved tooth surfaces.

Furthermore, by displaying the tool's cutting edge shape along with the cutting edge condition extraction data for the evaluation item, even non-expert users can determine whether or not the tool's cutting edge will be damaged, making it easier to determine whether the predicted machining results are possible.

As described above, according to the above aspect, it is possible to provide a machining shape simulation device that can predict vibrations at the machining point during gear generating cutting with high accuracy and improves the display of the prediction results.

1 is a functional block diagram of a vibration simulation device and a machining shape simulation device according to an embodiment of the present invention. FIG. 2 is a flow chart illustrating a usage mode of the vibration simulation device and the machining shape simulation device according to the present embodiment. FIG. 2 is a functional block diagram (procedure) of the rake angle calculation unit of FIG. 1 . FIG. 1 is a perspective view showing the basic operation of gear machining. FIG. 5 is a partial cross-sectional schematic view of the machining tool of FIG. 4 . This is a diagram explaining the operation of gear skiving, showing the relative positions of the workpiece and the machining tool, projected onto the Xw, Zw plane (viewed from the Yw direction). This is a diagram explaining the operation of gear skiving, showing the relative positions of the workpiece and the machining tool, projected onto the Xw, Yw plane (viewed from the Zw direction). 10A and 10B are diagrams illustrating the process from the start of cutting to the end of cutting in the tooth groove of the tool blade. 2 is a perspective view of a tool blade showing definition points in the definition point determination unit of FIG. 1 ; 10 is a diagram showing a cut vector L(i), a vector between definition points B(i), and a plane G(i). FIG. FIG. 10 is a diagram showing a blade surface normal vector N(i). FIG. 10 is a diagram showing a projection normal vector Ng(i). FIG. 10 is a diagram showing the projected rake angle αg(i). FIG. 10 is a diagram showing a portion removed in one tooth groove by one feed of one tool blade in the tooth groove direction. FIG. 14 is a diagram showing the relationship between the tool rotation angle and the rake angle in the cutting of FIG. 13 . FIG. 1 is a diagram showing a two-dimensional cutting model. 1 shows the reference state of a model of the workpiece. A model of the workpiece and a model of the machining tool are shown. 10 shows a model of the workpiece with the pin length changed. FIG. 10 is a diagram showing the final machining position according to each definition point P(k). FIG. 10 is a diagram showing the calculation results of each component of the cutting force. FIG. 10 is a diagram showing a prediction result obtained by the vibration simulation device of the present embodiment. FIG. 10 is a diagram showing a first prediction result of tooth surface property evaluation by the machining shape simulation device of the present embodiment. FIG. 10 is a diagram showing a second prediction result of tooth surface property evaluation by the machining shape simulation device of the present embodiment. FIG. 10 is a diagram showing a third prediction result of tooth surface quality evaluation by the machining shape simulation device of the present embodiment. FIG. 10 is a diagram showing a first prediction result of chatter vibration evaluation by the machining shape simulation device of the present embodiment. FIG. 10 is a diagram showing a second prediction result of chatter vibration evaluation by the machining shape simulation device of the present embodiment. FIG. 10 is a diagram showing a third prediction result of chatter vibration evaluation by the machining shape simulation device of the present embodiment. 1A is a conceptual diagram showing a model of a cutting edge shape in the cutting edge state display unit of this embodiment, and FIG. 1B is a conceptual diagram showing selection of an evaluation item. 1A is a conceptual diagram showing a model of the cutting edge shape and evaluation items in the cutting edge state display unit of this embodiment, and FIG. 1B is a conceptual diagram showing the values of the evaluation items in the evaluation area. 1A is a conceptual diagram showing evaluation items in the entire evaluation region, and FIG. 1B is a conceptual diagram showing the maximum value of the evaluation items in the entire evaluation region, in the cutting edge state display unit of this embodiment. FIG. 4 is a conceptual diagram showing time-series data and evaluation items in the cutting edge state display unit of the present embodiment. 10 is a conceptual diagram showing values at specific times in time-series data and specific values of evaluation items in the cutting edge state display unit of the present embodiment. FIG.

1. Basic Operations of Gear-Generating Cutting First, the basic operations of gear-generating cutting to which the machining shape simulation device 100 (see FIG. 1) equipped with the vibration simulation device 1 of this embodiment is applied will be described with reference to FIGS. 4 and 5. Here, in this embodiment, an example is given in which the gear-generating cutting is skiving, in which a gear 21 is formed on the inner peripheral surface of a workpiece 20 using a tool 10 that is a skiving cutter. However, this is also applicable to skiving, in which a gear is machined on the outer peripheral surface of the workpiece 20. It is also applicable to hobbing, in which a gear is machined on the outer peripheral surface of the workpiece 20 using a tool that is a hob cutter.

As shown in Figure 4, the workpiece 20 is formed in an annular shape, with a gear 21 formed on its inner circumferential surface. The workpiece 20 is also supported so that it can rotate around its central axis Zw. In other words, the workpiece 20 can rotate about the C axis.

As shown in Figures 4 and 5, the tool 10 has multiple tool blades 11 on its outer periphery and is supported rotatably around the central axis Zt of the tool 10. In other words, the tool 10 is capable of U-axis rotation. Each tool blade 11 is formed as a ridge. Each tool blade 11 has a side surface 11a in the extension direction of the tool blade 11, an end surface 11b in the extension direction, and a radial outer surface 11c. In gear generating cutting, the end surface 11b becomes the rake face, and the side surface 11a and the radial outer surface 11c become the relief surfaces. In particular, the side surface 11a becomes the side relief surface, and the radial outer surface 11c becomes the front relief surface.

In this embodiment, the tool blade 11 has a helix angle γ1 with respect to the central axis Zt of the tool 10. However, the tool blade 11 may be formed so that the helix angle γ1 is zero. The radial outer surface 11c of the tool blade 11 is inclined with respect to the central axis Zt. In other words, the circumscribing surface of the tool blade 11 is formed in a conical shape. The inclination angle ξb of the radial outer surface 11c of the tool blade 11 corresponds to the clearance angle in cutting. The end face 11b of the tool blade 11 is inclined by an angle ξa with respect to a plane perpendicular to the central axis Zt. The inclination angle ξa of the end face 11b of the tool blade 11 corresponds to the rake angle in cutting. Although not shown, the side surface 11a of the tool blade 11 has a side clearance angle, and the edge angle of the end face 11b of the tool blade 11 is zero.

As shown in Figure 4, the central axis Zt of the tool 10 is at an angle relative to an axis parallel to the central axis Zw of the workpiece 20, i.e., at an intersection angle θ (see Figure 6A). In other words, the central axes Zt and Zw of the two are not parallel.

In this state, while synchronizing the rotation of the tool 10 and the rotation of the workpiece 20, as shown by the thick arrow in Figure 4, the tool 10 is moved straight relative to the workpiece 20 in the direction indicated by arrow f, which is opposite and parallel to the direction of the central axis Zw of the workpiece 20. Note that the tool 10 may be moved in the direction f, or the workpiece 20 may be moved in the direction opposite to the direction f. In other words, at least one of the tool 10 and the workpiece 20 is moved so that the tool 10 moves in the direction f relative to the workpiece 20.

Because the central axis Zt of the tool 10 and the central axis Zw of the workpiece 20 form an intersection angle θ, a relative velocity is generated between the tool 10 and the workpiece 20 at the machining point. As a result, the workpiece 20 is cut. As a result, tooth grooves 22 of the gear 21 are formed on the inner surface of the workpiece 20, as shown in Figure 4. Note that Figure 4 shows the state in which the tooth grooves 22 have been machined partway into the workpiece 20, but by continuing the above operation, tooth grooves 22 are formed along the entire axial length of the workpiece 20.

2. Gear-generating cutting device A gear-generating cutting device for carrying out the gear-generating cutting method of this embodiment may be, for example, a 5-axis machining center (not shown). That is, a device may be used that can relatively move the tool 10 and the workpiece 20 linearly in three mutually orthogonal axis directions, rotate the tool 10 and the workpiece 20 about their respective axes (U-axis rotation, C-axis rotation), and tilt the central axis Zt of the tool 10 and the central axis Zw of the workpiece 20.

3. Overview of the Vibration Simulation Device 1 and the Machined Shape Simulation Device 100 An overview of the vibration simulation device 1 and the machined shape simulation device 100 according to an embodiment of the present invention will now be described. As shown in FIGS. 6A and 6B , in gear skiving, the workpiece 20 and the tool 10 are rotated synchronously (U-axis rotation, C-axis rotation) while the tool 10 is fed in the direction of the center axis Zw of the workpiece 20. At this time, the rotation angle η of the workpiece 20 and the rotation angle σ of the tool 10 (tool blade 11) (hereinafter referred to as the "tool rotation angle σ") are related by the following equation (1). Here, Jw is the number of teeth of the gear 21, Jt is the number of teeth of the tool blade 11, and δ is the correction angle. The machined shape simulation device 100 may be incorporated into the control device of a gear generating cutting device. The machining shape simulation device 100 may also be an embedded system such as a PLC (Programmable Logic Controller) or a CNC (Computer Numerical Control) device, or may also be a personal computer or a server.

In gear skiving, multiple tool blades 11 formed on the outer periphery of the tool 10 are simultaneously involved in cutting multiple tooth grooves 22 (see Figure 4) of a gear 21 formed on the inner periphery of the workpiece 20, but typically each tool blade 11 and each tooth groove 22 is geometrically in the same cutting state.

The machining shape simulation device 100 of this embodiment therefore focuses on the rotation of one tool blade 11 in one tooth space 22 and performs analysis by rotating the tool 10 by a small angle, i.e., by slightly increasing the tool rotation angle σ in equation (1). Furthermore, by focusing on the feed of one tool blade 11 in one tooth space 22, the range from the start of cutting to the end of cutting for one tool blade 11 becomes clear. That is, as shown in the order of (a), (b), and (c) in Figure 7, the tool blade 11 starts cutting the tooth space 22 at tool rotation angle σs, passes through tool rotation angle σ = 0, and ends cutting the tooth space 22 at tool rotation angle σe.

This allows the cutting state of a single tool blade 11 to be analyzed in more detail and in a shorter time than before. It also makes it easy to calculate the tool blade characteristics necessary for the proper design of the tool 10, namely the rake angle of the tool blade 11, and the cutting force exerted by the tool blade 11 involved in cutting.

As mentioned above, the shape of the tool blade 11 of the tool 10 is very complex. Therefore, as will be described in detail later, as shown in Figure 8, the boundary lines between the end face 11b (rake face) of the tool blade 11 and the side face 11a and radial outer face 11c (flank face) are divided into multiple regions ΔP(i, i+1). This allows two-dimensional processing for each region ΔP(i, i+1).

In other words, for each region ΔP(i, i+1), a two-dimensional cutting model is used to calculate the rake angle α(i) and calculate the cutting force FH(i). The calculated cutting force FH(i) is then used to calculate the cutting force FH for the entire region. Furthermore, the relative vibration of the tool 10 and workpiece 20 is calculated using the cutting force FH(i) and the dynamic characteristics of the tool 10 and workpiece 20. Note that in this embodiment 1, unless otherwise specified, the physical quantity for "vibration" and "relative vibration" is displacement, but this is not limited to this and acceleration or velocity may also be used. This is explained in detail below.

4. Details of the vibration simulation device 1 and the machining shape simulation device 100 The vibration simulation device 1 and the machining shape simulation device 100 will be described. The vibration simulation device 1 and the machining shape simulation device 100 are configured with one or more arithmetic processing devices and storage devices, and as shown in Fig. 1, the vibration simulation device 1 includes an analysis condition setting unit 110, a shape defining unit 120, an interference region calculation unit 130, a cutting force calculation unit 140, a dynamic characteristic defining unit 150, a vibration calculation unit 160, an output unit 170, and an update unit 175. The machining shape simulation device 100 includes a vibration simulation device 1, a tooth surface property evaluation unit 180, a chatter vibration evaluation unit 190, a display condition setting unit 200, an integrated display unit 201, and a cutting edge state evaluation unit 210.

Here, in explaining the vibration simulation device 1 and the machining shape simulation device 100, while referring to the flow diagram showing the usage mode of the machining shape simulation device 100 shown in Figure 2, the following will be explained in this order: (4-1) Explanation of shape definition processing, (4-2) Explanation of rake angle calculation processing, (4-3) Explanation of two-dimensional cutting model, (4-4) Explanation of cutting depth calculation processing, (4-5) Explanation of cutting force calculation processing, (4-6) Explanation of relative vibration calculation processing, (4-7) Explanation of information update and calculation result output, (4-8) Explanation of tooth surface property evaluation, (4-9) Explanation of chatter vibration evaluation, and (4-10) Explanation of cutting edge condition evaluation.

4-1. Shape Definition Processing The shape definition processing will be described with reference to the analysis condition setting unit 110 and the shape definition unit 120 in FIG. 1. First, the analysis condition setting unit 110 acquires analysis conditions required for simulation in the vibration simulation device 1 and the machining shape simulation device 100 (step S1 in FIG. 2). The analysis conditions include tool specifications, which are the specifications of the tool 10, workpiece specifications, which are the specifications of the workpiece 20, and machining conditions in a gear generating cutting device (not shown). The analysis conditions may have a predetermined analysis range and may also include other information. The analysis condition setting unit 110 can acquire the analysis conditions by having the user input some or all of the analysis conditions, or by retrieving some or all of the analysis conditions pre-stored in a storage unit (not shown).

The shape definition unit 120 defines the shapes of the tool 10 and workpiece 20 based on the analysis conditions acquired by the analysis condition setting unit 110 (step S2 in Figure 2). In this embodiment, the shapes of the tool 10 and workpiece 20 are defined by a point cloud consisting of multiple points located on the surfaces of the tool 10 and workpiece 20. Specifically, for the tool 10, as shown in Figure 8, the boundary lines between the end face 11b (rake face) of each tool blade 11 and the side face 11a and radial outer surface 11c (flank face) are defined as multiple definition points P(k). In other words, by connecting multiple definition points P(k) (where k = 1 to n, n is a natural number) with straight lines, an approximation of the boundary line on the tool blade 11 is obtained. Here, although Figure 8 shows 13 definition points P(1) to P(13), the number of definition points P(k) can be set freely. Furthermore, if only the tooth flanks of the gear 21 are machined and the tooth bottom is not machined, the multiple definition points P(k) can be defined only on the boundary line between the end face 11b, which is the rake face, and the side face 11a, which is the side relief face, and not on the boundary line between the end face 11b and the radially outer surface 11c, which is the front relief face.

Here, the terminology used in the subsequent processing regarding the tool blade 11 will be explained with reference to Figure 8. The area between two adjacent definition points P(i) and P(i+1) is referred to as the inter-definition point area ΔP(i, i+1). For example, the area between definition points P(1) and P(2) is ΔP(1, 2). Furthermore, the midpoint between two adjacent definition points P(i) and P(i+1) is referred to as Pc(i, i+1). For example, the midpoint between definition points P(1) and P(2) is Pc(1, 2).

As shown in Figure 16, the workpiece portion of the workpiece 20 is represented by erecting pins 26 of a specified length at specified intervals on a reference plane and creating triangular patches 27 at the tips of the pins. However, because the workpiece 20 is cylindrical, the reference plane is the cylindrical surface whose central axis is the central axis Zw of the workpiece 20. The shape of the workpiece 20 is defined by erecting pins 26 of a specified length at specified intervals on this reference cylindrical surface, parallel to the normal direction to the reference cylindrical surface, with the pins 26 oriented toward the center of the reference cylindrical surface when machining the inner peripheral surface and oriented outward from the center of the reference cylindrical surface when machining the outer peripheral surface. Note that in Figures 16 to 18, the reference cylindrical surface is represented as a plane for convenience.

4-2. Rake Angle Calculation Process Next, the rake angle calculation process will be described with reference to the cutting-in vector calculation unit 131 and the rake angle calculation unit 132 included in the interference area calculation unit 130 in Fig. 1. For each inter-definition point area ΔP(i, i+1), the cutting-in vector calculation unit 131 calculates a cutting-in vector L(i) along which the inter-definition point area ΔP(i, i+1) moves in the cutting direction while the tool 10 rotates from the rotation angle σ1, which is the first time, to the rotation angle σ2, which is the second time. However, the direction in which the entire inter-definition point area ΔP(i, i+1) moves is not easily calculated.

As shown in Figure 9, the vector Lc(i) along which the midpoint Pc(i, i+1) of two adjacent definition points P(i) and P(i+1) moves in the cutting direction is calculated as the cutting vector L(i). In this way, by using the midpoint Pc(i, i+1), the vector along which this point moves can be calculated easily and reliably.

The rake angle calculation unit 132 calculates the rake angle α(i) based on the cutting vector L(i). The rake angle α(i) is the rake angle when cutting the workpiece 20 using the inter-definition point area ΔP(i, i+1). Here, the rake angle calculation unit 132 calculates the rake angle α(i) using the procedure shown in Figure 3.

The calculation of the rake angle α(i) will be explained below with reference to Figures 3 and 9 to 12. First, as shown in Figure 3, the cutting vector L(i) is calculated by the cutting vector calculation unit 131 as described above (reference numeral S31 in Figure 3), and then the inter-definition point vector B(i) is calculated (S32 in Figure 3). The inter-definition point vector B(i) is a vector connecting two adjacent definition points P(i) and P(i+1), as shown in Figure 9. Here, the midpoint Pc(i, i+1) is located at the middle position of the inter-definition point vector B(i).

Next, based on the cut vector L(i) calculated by the cut vector calculation unit 131 and the inter-definition point vector B(i), a plane G(i) that includes the cut vector L(i) and is perpendicular to the inter-definition point vector B(i) is calculated (reference number S33 in Figure 3). Plane G(i) is as shown in Figure 9.

Here, to define the plane G(i), the normal vector C(i) for defining the plane is used. In other words, the normal vector C(i) for defining the plane is a vector that passes through the midpoint Pc(i, i+1) and is perpendicular to the cut vector L(i) and the vector between the definition points B(i). Therefore, the plane G(i) can be defined as a plane that passes through the midpoint Pc(i, i+1) and includes the cut vector L(i) and the normal vector C(i) for defining the plane.

The purpose of calculating this plane G(i) is to use a two-dimensional cutting model based on two-dimensional cutting theory, as described above. In other words, by applying the two-dimensional cutting model to the plane G(i), the cutting force FH(i) on that plane G(i) is calculated.

Next, the normal vector N(i) (hereinafter referred to as the "blade surface normal vector") of the tool blade 11 at the midpoint Pc(i, i+1) is calculated (reference numeral S34 in Figure 3). Here, the blade surface normal vector N(i) cannot be obtained simply by determining two adjacent definition points P(i) and P(i+1). Therefore, as shown in Figure 10, three or more adjacent definition points P(k) including the definition points P(i) and P(i+1) are used. Here, three definition points P(i-1), P(i), and P(i+1) are used.

As shown in Figure 10, a plane Q(i) is determined that passes through the three definition points P(i-1), P(i), and P(i+1). Then, on the plane Q(i), the vector that passes through the midpoint Pc(i, i+1) and is perpendicular to the vector B(i) between the definition points is defined as the blade surface normal vector N(i).

Next, after calculating the plane G(i) and the blade surface normal vector N(i), the projection normal vector Ng(i) obtained by projecting the blade surface normal vector N(i) onto the plane G(i) is calculated (reference number S35 in Figure 3).

Here, as shown in Figure 11, plane G(i) and plane Q(i) are not necessarily the same plane. Therefore, although the blade surface normal vector N(i) is located on plane Q(i), it is not necessarily located on plane G(i). Therefore, as described above, by projecting the blade surface normal vector N(i) onto plane G(i), the projected normal vector Ng(i) located on plane G(i) is obtained.

Next, the projected rake angle αg(i), which is the angle between the projected normal vector Ng(i) and the cutting vector L(i) on the plane G(i), is calculated (reference number S36 in Figure 3). The projected rake angle αg(i) is as shown in Figure 12. Here, because the projected rake angle αg(i) is calculated on the plane G(i), it differs from the actual rake angle α(i).

However, in order to use a two-dimensional cutting model on plane G(i), the projected rake angle αg(i) is estimated as the rake angle α(i). In this way, the rake angle calculation unit 132 calculates the rake angle α(i) (= projected rake angle αg(i)).

Here, as shown in Figure 13, in one feed of one tool blade 11 in one tooth groove 22 in the tooth groove direction (direction of the arrow in the figure), for example, the portion 23 shown by the hatched line in the figure becomes an interference area and is removed. In other words, the tool blade 11 rotates as the feed proceeds, and when the tool rotation angle σ is σs, it is located at the cutting start position (position shown by the two-dot chain line in the figure), when the tool rotation angle σ is σa, σb, or σc, it is located at the area where the removed portion (interference area) 23 overlaps with the one-dot chain line in the figure, and when the tool rotation angle σ is σe, it is located at the cutting end position (position shown by the two-dot chain line in the figure).

The rake angle αg(i) can be determined in the range from the start of cutting to the end of cutting for one tool blade 11 in one tooth groove 22. For example, as shown in Figure 14, the rake angle αg(i) relative to the tool rotation angle σ can be determined separately for the left cutting surface of the tool blade 11 (dashed line in the figure, definition points P(1)-P(4) in Figure 8), the cutting edge of the tool blade 11 (solid line in the figure, definition points P(5)-P(9) in Figure 8), and the right cutting surface of the tool blade 11 (dash-dotted line in the figure, definition points P(10)-P(13) in Figure 8) in the range from the start of cutting (tool rotation angle σs) to the end of cutting (tool rotation angle σe).

Each line segment representing the rake angle αg(i) is a set of values at the midpoint Pc(i, i+1) of the tool blade 11. When the tool rotation angle σ is 0, this is when the tool blade 11 reaches the center of the tooth groove 22 in the tooth groove direction (the same applies to the following figures). Where the calculated rake angle αg(i) becomes negative, the cutting depth increases and the cutting force becomes locally large, so the specifications of the tool blade 11 are changed so that the rake angle αg(i) does not become negative.

Next, a two-dimensional cutting model based on two-dimensional cutting theory will be described with reference to Fig. 15. Fig. 15 shows the cutting model on the plane G(i) described above. In Fig. 15, a workpiece 20 is cut by the tool blade 11 of a tool 10.

Here, on plane G(i), the rake face of the tool blade 11 is the end face 11b, the side relief face is the side face 11a, and the front relief face is the radial outer surface 11c. The rake angle is αg(i). The cutting depth is d1(i), and the shear angle is φ(i). At this time, the cutting vector by the tool blade 11 is L(i), and the normal vector of the tool blade 11 is Ng(i). The cutting vector L(i) corresponds to the principal force Fc(i) in the two-dimensional cutting model, and the thrust force Ft(i) is illustrated as shown in Figure 15. Here, the principal force Fc(i) and thrust force Ft(i) at the relevant part are respectively expressed as in equation (2).

In equation (2), τs is the shear stress and is obtained in advance based on the target material, etc. The cutting cross-sectional area A can be expressed as the product of b(i), the distance between two adjacent definition points P(i) and P(i+1), and the cutting depth d1(i) of the area between the definition points ΔP(i, i+1). Note that the cutting depth d1(i) is the average of the cutting depth (corresponding to the radial depth) at definition point P(i) and the cutting depth at definition point P(i+1). φ(i) is the shear angle, which can be obtained from publicly known technical information. αg(i) is the projected rake angle mentioned above. β is the rake face friction angle, which is determined empirically. As described above, calculating the rake angle αg(i) on plane G(i) enables the application of a two-dimensional cutting model. Note that the same application as for the two-dimensional model can be applied even when a three-dimensional cutting model is used instead of the two-dimensional cutting model.

4-4. Cut-in Amount Calculation Processing In the above two-dimensional cutting model, if the cut-in amount d1(i) can be obtained, the cutting force FH(i) can be obtained. If the shape of the workpiece 20 immediately before and the shape of the workpiece 20 when cutting this time are known, the cut-in amount d1(i) can be obtained from the difference between the two. This will be described in detail below with reference to FIGS. 17 to 19.

Here, the cutting depth calculation process will be explained with reference to the intersection calculation unit 133, removal length calculation unit 134, and final processing position extraction unit 135 in Figure 1.

As shown in FIG. 17, the intersection calculation unit 133 considers the case where the tool blade 11 moves relative to the workpiece 20 using the shape of the workpiece 20 when the tool rotation angle σ defined by the shape definition unit 120 increases slightly from σ1 to σ2 and the infinitesimal line segment movement trajectory of the tool blade 11 of the tool 10. In this embodiment, the infinitesimal line segment movement trajectory from when the boundary 11s between the end face 11b (the rake face) and the side face 11a and radial outer face 11c (the flank face) is at a first time position 11s1 where the tool rotation angle σ is σ1 to a second time position 11s2 where the tool rotation angle σ increases slightly to σ2 is defined by a triangular patch trajectory plane 11p. Then, by moving the tool blade 11 relatively, the intersection of each pin 26 representing the workpiece 20 and the trajectory plane 11p of the tool blade 11 is calculated.

If the intersection calculation unit 133 finds an intersection, the removal length calculation unit 134 changes the length of each pin 26 representing the workpiece 20, as shown in FIG. 18. In other words, a portion of the workpiece 20 is cut by the tool blade 11 when the tool rotation angle σ increases slightly from σ1 to σ2, and this is stored as the shape after cutting. At this time, the removal length calculation unit 134 stores the removal length of each pin 26. This removal length of the pin 26 corresponds to the amount of cutting when the tool rotation angle σ increases slightly from σ1 to σ2 (when the first time has elapsed to the second time), and the interference area between the tool 10 and the workpiece 20 is calculated (S3 in FIG. 2).

The final machining position extraction unit 135 extracts the final machining position of each definition point P(k) representing the tool blade 11 while the tool rotation angle σ increases slightly from σ1 to σ2. Figure 19 plots the points to which each definition point P(k) moves while the tool rotation angle σ increases slightly from σ1 to σ2. Open circles indicate the final machining position of each definition point P(k), and black circles indicate positions other than the final machining position of each definition point P(k).

In other words, the final machining position for each definition point P(k) corresponds to the position of each definition point P(k) at tool rotation angle σ2. If these positions are known, the cutting depth at each definition point P(k) can be calculated from the final machining position and the shape of the workpiece 20 immediately before. In other words, it is possible to grasp the change in the shape of the workpiece 20 as the tool rotation angle σ increases slightly from σ1 to σ2.

The cutting depth d1(i) in the two-dimensional cutting model corresponds to the average of the cutting depth at definition point P(i) (corresponding to the radial depth) and the cutting depth at definition point P(i+1). In other words, since the cutting depth at each definition point P(k) can be obtained, the cutting depth d1(i) at the midpoint Pc(i, i+1) can be calculated.

In this way, the final machining position extraction unit 135 calculates the final machining position for each definition point P(k), calculates the cutting depth at each definition point P(k), and further calculates the cutting depth d1(i) at the midpoint Pc(i, i+1). The intersection calculation unit 133 calculates the intersection between each pin 26 representing the workpiece 20 and the trajectory plane 11p of the tool blade 11 within the range from the start to the end of cutting of one tooth groove 22 with one tool blade 11. Then, each time the cutting of one tooth groove 22 with one tool blade 11 is repeatedly performed from the start to the end of cutting, the shape of the workpiece 20 is updated and the intersection between each pin 26 representing the workpiece 20 and the trajectory plane 11p of the tool blade 11 is calculated.

4-5. Cutting Force Calculation Process Next, the calculation process of the cutting force FH(i) for each region ΔP(i, i+1) using the two-dimensional cutting model will be described. This process will be explained with reference to FIG. 1 regarding the cutting force calculation unit 140.

The cutting force calculation unit 140 in FIG. 1 calculates the cutting force FH(i) for each region ΔP(i, i+1) using the two-dimensional cutting model shown in FIG. 15 (S4 in FIG. 2). This cutting force FH(i) can be calculated by dividing the principal force Fc(i) and thrust force Ft(i) in the above-mentioned equation (2) into components in the Xw, Yw, and Zw directions, which are the three orthogonal axial directions of the workpiece 20, and then adding up the components in each direction.

In other words, the principal force Fc(i) and thrust force Ft(i) can be divided into Xw, Yw, and Zw direction components as follows:

Here, we define a unit vector as in equation (4).

Then, the components Fcx(i), Fcy(i), and Fcz(i) of the principal force Fc(i), and the components Ftx(i), Fty(i), and Ftz(i) of the thrust force Ft(i) are expressed as in equation (5) below.

The components FHx(i), FHy(i), and FHz(i) of the cutting force FH(i) are expressed as in equation (6) using the components of the principal force Fc(i) and thrust force Ft(i).

The cutting force FH in the entire region is the sum of the cutting forces FH(i) in each region ΔP(i, i+1), so the components FHx, FHy, and FHz of the cutting force FH are expressed as in equation (7).

The cutting force FH can be calculated for the entire region based on equation (7). The calculation results for each component of the cutting force FH are shown in Figure 20, for example, and are close to the actual measured values, confirming that the calculation results are highly accurate.

Next, a description will be given of a process for calculating the relative vibration between the tool 10 and the workpiece 20. The process for calculating the relative vibration will be described with reference to the dynamic characteristics defining unit 150, the vibration calculating unit 160, and the output unit 170 in FIG.

First, the dynamic characteristics definition unit 150 defines the relative dynamic characteristics or individual dynamic characteristics between the tool 10 and workpiece 20. In this embodiment, the definition is based on information acquired by the analysis condition setting unit 110. For example, the analysis condition setting unit 110 can use the dynamic characteristics defined by the dynamic characteristics definition unit 150 as the definition result based on information acquired by a hammering test or the like. Note that the relative dynamic characteristics can be defined based on individually calculated values of the tool 10 and workpiece 20. Furthermore, if the dynamic characteristics of the workpiece 20 can be ignored, the dynamic characteristics of the tool 10 can be used as the relative dynamic characteristics.

The vibration calculation unit 160 includes a transfer function processing unit 161 and a restoring action calculation unit 162. The transfer function processing unit 161 calculates the relative vibration between the tool 10 and the workpiece 20 based on a transfer function from the relative dynamic characteristics defined by the dynamic characteristics definition unit 150 and the cutting force FH (S5 in Figure 2). In this embodiment, the transfer function processing unit 161 outputs displacement, velocity, and acceleration.

The restoring action calculation unit 162 calculates a restoring action that increases nonlinearly with an increase in the amplitude of the relative vibration calculated by the transfer function processing unit 161. In this embodiment, the transfer function used in the transfer function processing unit 161 or the cutting force FH input to the transfer function processing unit 161 is corrected based on at least one of the displacement, velocity, and acceleration output by the transfer function processing unit 161. The restoring action calculation unit 162 is appropriately designed, for example, to reflect the effect of vibration suppression due to process damping when cutting the workpiece 20 with the tool 10.

As shown in Figure 21, if no correction is made by the restoring action calculation unit 162, the displacement calculated by the vibration calculation unit 160 will diverge over time, but this divergence is suppressed by correcting the transfer function or cutting force FH by the restoring action calculation unit 162.

4-7. Information Update and Output of Calculation Results Next, the information update by the update unit 175 and the output by the output unit 170 will be described.
First, the calculation result of the transfer function processing unit 161 is input to the update unit 175 and output by the output unit 170. The calculation result of the cutting force calculation unit 140 is also output by the output unit 170. The update unit 175 updates the relative position between the tool 10 and the workpiece 20 and the workpiece shape based on the interference region calculated by the interference region calculation unit 130 and the relative vibration calculated by the vibration calculation unit 160 (S6 in FIG. 2). That is, the relative positions of the tool 10 and the workpiece 20 are updated, and the shape resulting from removing the interference region is used as the updated workpiece shape. Then, based on the updated information, the interference region calculation unit 130 calculates the interference region, the cutting force calculation unit 140 calculates the cutting force, and the vibration calculation unit 160 calculates the relative vibration, repeating this process until machining of the workpiece 20 is completed (No in S7 in FIG. 2), thereby calculating the vibration simulation result.

When processing is complete (Yes in S7 in Figure 2), the output unit 170 outputs the calculation results of the vibration calculation unit 160. The output results of the output unit 170 are shown, for example, in Figure 21, and show that the vibration displacement with transfer function correction is relatively close to the actual measured value, confirming that calculations can be performed with high accuracy.

4-8. Tooth Flank Property Evaluation Next, a description will be given of tooth flank property evaluation using the machining shape simulation device 100 shown in Fig. 1. In the first embodiment, the tooth flank property evaluation and chatter vibration evaluation, which will be described later, are processed in parallel.

Furthermore, prior to tooth surface characteristic evaluation, display conditions are set using the display condition setting unit 200 shown in FIG. 1 (step S8 in FIG. 2). Display conditions can include the tooth trace direction range, tooth profile direction range, and error range to be displayed in the predicted tooth surface shape display unit 182 shown in FIG. 1, the number and tooth trace direction positions of tooth profiles to be displayed in the predicted tooth profile shape display unit 184, and the frequency range and amplitude range to be displayed in the vibration state display unit 193.

Tooth surface quality evaluation is processed in the following order. First, in step S9 of Figure 2, the workpiece shape recorded by the machining result prediction unit 181 of the tooth surface quality evaluation unit 180 is updated based on the output result of the output unit 170, using the shape of the machined workpiece 20 last updated by the update unit 175 shown in Figure 1. Then, in step S10 of Figure 2, the predicted tooth surface shape, predicted tooth trace shape, and predicted tooth profile shape are displayed.

The predicted tooth flank shape is displayed based on the display conditions set by the predicted tooth flank shape display unit 182. As shown in Figures 22(a), 23(a), and 24(a), for example, the predicted tooth flank shape is displayed as a contour diagram with the tooth trace direction and tooth profile direction as the display axes, and includes data on the difference from the reference surface. In this embodiment 1, an involute tooth profile is used as the reference surface, and the difference from the involute tooth profile is displayed as the error. In other words, the predicted tooth flank shape displayed by the predicted tooth flank shape display unit 182 is a contour diagram with the tooth trace direction and tooth profile direction as the display axes and showing the error.

The predicted tooth trace shape is displayed by the predicted tooth trace shape display unit 183 based on the display conditions set in the display condition setting unit 200. The predicted tooth trace shape is displayed as a scatter plot of a cross section at a specified tooth profile direction position, as a relationship with the error, which is the difference from the involute tooth profile in the tooth trace direction, as shown, for example, in Figures 22(b), 23(b), and 24(b).

The predicted tooth profile shape is displayed by the predicted tooth profile shape display unit 184 based on the display conditions set in the display condition setting unit 200. For example, as shown in Figures 22(c), 23(c), and 24(c), the predicted tooth profile shape is shown as a scatter plot of a cross section at a specified tooth trace direction position, showing the difference from the involute tooth profile in the tooth profile direction as a relationship with the error.

Then, the display contents of each display unit 182-184 in step S10 are laid out and displayed on a single screen by the integrated display unit 201 shown in FIG. 1 in the display modes shown in FIGS. 22-24, respectively. Although not shown, the integrated display unit 201 may also display various types of gear accuracy numerical data, such as total tooth profile error and total tooth trace error, calculated in advance by the machining result prediction unit 181 based on the workpiece shape, along with the display contents shown in FIGS. 22-24. Furthermore, if the workpiece is a helical gear, the layout may also display the cross-sectional shape along the meshing progression line. Furthermore, the layout may also display the results of Fourier frequency analysis of the cross-sectional shape along the meshing progression line as a gear noise evaluation index.

Note that Figures 22 to 24 are examples of predicted machining results under normal conditions where no chatter vibration occurs during machining, a first abnormal condition where relatively small chatter vibration occurs during machining, and a second abnormal condition where relatively large chatter vibration occurs during machining. Under normal conditions, errors are predicted to be small in the tooth flank shape, tooth trace shape, and tooth profile shape, as shown in Figures 22(a) to (c). Under the first abnormal condition, errors are predicted to be slightly larger than normal in the tooth flank shape, tooth trace shape, and tooth profile shape, as shown in Figures 23(a) to (c). Under the second abnormal condition, errors are predicted to be significantly larger than normal in the tooth flank shape, tooth trace shape, and tooth profile shape, as shown in Figures 24(a) to (c).

It was confirmed that the prediction reflected the presence or absence of chatter vibration and the extent of chatter vibration. Therefore, it can be seen that by using the prediction results of the machining shape simulation device 100, it is possible to predict with high accuracy the occurrence of chatter vibration during machining, even when using the prediction results of the tooth flank shape.

4-9. Chatter Vibration Evaluation Meanwhile, chatter vibration evaluation in step S11 shown in FIG. 2 is performed by the chatter vibration evaluation unit 190 shown in FIG. 1. In the chatter vibration evaluation unit 190, the frequency analysis unit 191 acquires time-series relative vibration from the calculation results of the vibration calculation unit 160 output by the output unit 170, or acquires time-series cutting force, which is the calculation result of the cutting force calculation unit 140. Thereafter, in step S12, the frequency analysis unit 191 performs calculation by frequency analysis. Note that in the first embodiment, the physical quantity of the relative vibration output by the output unit 170 is displacement, but acceleration or velocity may also be used. Furthermore, the frequency analysis in the frequency analysis unit 191 can be performed by short-time Fourier transform, fast Fourier transform, wavelet transform, or the like. In the first embodiment, the time-series relative vibration is calculated by short-time Fourier transform.

Then, in step S13 of FIG. 2, the vibration generation state is evaluated by the vibration generation evaluation unit 192 shown in FIG. 1, and the results are created as a contour diagram in which the display axes are frequency and machining time, the display range of which is set based on the display conditions set by the display condition setting unit 200, and the displacement amplitude values are represented by a color map such as a grayscale. The contour diagram is then displayed by the vibration state display unit 193. The frequency range displayed in the contour diagram is a frequency range that includes the cutting edge passing frequency component and chatter vibration frequency component described below. Note that the display axis of the contour diagram displayed by the vibration state display unit 193 may be tooth trace direction position instead of machining time. Furthermore, the contour diagram displayed by the vibration state display unit 193 may be displayed on a single screen together with the display units 182-184 of the tooth surface characteristic evaluation unit 180 by the integrated display unit 201 shown in FIG. 1, laid out together.

Figures 25 to 27 show examples of contour diagrams that display the evaluation results of chatter vibration evaluation of the time-series relative vibration predicted under normal conditions where no chatter vibration occurs during machining, a first abnormal condition where relatively small chatter vibration occurs during machining, and a second abnormal condition where relatively large chatter vibration occurs during machining.

In the contour diagram shown in Figure 25, only the cutting edge passing frequency component is detected from the start to the end of machining, and no chatter vibration frequency component is detected, indicating that chatter vibration does not occur during machining. The cutting edge passing frequency is a value calculated by multiplying the tool rotation frequency by the number of tool teeth. The fact that the main frequency component of vibration generated during machining is only this cutting edge passing frequency component indicates the occurrence of so-called forced vibration, which occurs directly when the tool teeth come into contact with the workpiece. The chatter vibration frequency is a frequency near the natural frequency of the dynamic stiffness between the tool and workpiece, and varies depending on the machining conditions input into the vibration simulation device 1. In Figures 25 to 27, the frequency is higher than the cutting edge passing frequency, but it can also be lower than the cutting edge passing frequency.

On the other hand, the contour diagram shown in Figure 26 detects the cutting edge passing frequency component from the start to the end of machining, and furthermore, the chatter vibration frequency component is detected at a relatively small displacement amplitude, indicating that small chatter vibration occurs during machining. Furthermore, the contour diagram shown in Figure 27 detects only the cutting edge passing frequency component from the start to the end of machining, and furthermore, the chatter vibration frequency component is detected at a relatively large displacement amplitude, indicating that large chatter vibration occurs during machining. Frequency components detected around the chatter vibration frequency component are sidebands of chatter vibration, and arise due to the intermittent nature of cutting.

Although not shown, it was confirmed that when the cutting force calculated by the cutting force calculation unit 140 was obtained in step S11 shown in Figure 2 and chatter vibration evaluation was performed by the processing of steps S12 and S13, a contour diagram similar to that obtained when using the above-mentioned relative vibration was obtained.

As described above, it has been confirmed that the contour diagrams shown in Figures 25, 26, and 27 reflect the presence or absence of chatter vibration and the extent of chatter vibration. Therefore, it can be seen that by performing chatter vibration evaluation using the machining shape simulation device 100, it is possible to predict with high accuracy the occurrence of chatter vibration during machining.

4-10. Cutting Edge Condition Evaluation Furthermore, the cutting edge condition evaluation by the cutting edge condition evaluation unit 210 shown in Fig. 1 is performed in steps S14 to S16 in parallel with steps S4 to S6 shown in Fig. 2. First, in step S14, the cutting edge condition extraction unit 212 in the cutting edge condition evaluation unit 210 shown in Fig. 1 extracts cutting edge condition extraction data during machining in multiple evaluation regions of the cutting edge shape stored in the cutting edge model storage unit 211 based on at least the calculation results of the interference region calculation unit 130.

In this embodiment, the cutting edge model storage unit 211 stores model data of the cutting edge shape for the shape of the tool 10 defined by the shape definition unit 120. The multiple evaluation areas for the cutting edge shape stored in the cutting edge model storage unit 211 are stored as a point cloud, with each point representing an evaluation area. For example, the evaluation area for a cross section perpendicular to the tooth trace direction at any position on the cutting edge shape consists of a point cloud displayed on the cutting edge state display unit 214 (described below), as shown in Figure 28(a), with each point representing an evaluation area.

Next, proceed to step S15, and input the evaluation items in the cutting edge condition extraction data into the evaluation item input section 213 in the cutting edge condition evaluation unit 210 shown in Figure 1. The evaluation items include cutting resistance, and can also include at least one of the depth of cut, rake angle, and surface pressure.

The cutting resistance, an evaluation item in the cutting edge condition extraction data, is the maximum value or integrated value of the cutting resistance during machining at a point in the evaluation area of the cutting edge. This cutting resistance is calculated by the cutting edge condition extraction unit 212 based on at least the calculation results of the vibration calculation unit 160 and the cutting force calculation unit 140.

The depth of cut, an evaluation item in the cutting edge condition extraction data, is the maximum depth of cut during machining at a point in the evaluation area of the cutting edge. The rake angle, an evaluation item, is the minimum depth of cut during machining at a point in the evaluation area of the cutting edge. The depth of cut and rake angle are calculated by the cutting edge condition extraction unit 212 based on at least the calculation results of the interference area calculation unit 130.

The surface pressure, an evaluation item in the cutting edge condition extraction data, is the maximum surface pressure during machining that occurs at a point in the evaluation area of the cutting edge. This surface pressure is calculated by the cutting edge condition extraction unit 212 based on at least the calculation results of the cutting force calculation unit 140.

The user of the machining shape simulation device 100 can input evaluation items into the evaluation item input unit 213 in step S15. In this embodiment, the user can do this by operating the input terminal as follows. First, as shown in FIG. 28(a), the cutting edge condition display unit 214, which will be described later, displays input fields in the evaluation item input unit 213 where the user can input evaluation items. Then, the user can use the input terminal to hover the pointer over the evaluation item input unit 213 on the cutting edge condition display unit 214 and select it, thereby displaying a pull-down menu 213a listing evaluation items, as shown in FIG. 28(a). The user can input the desired evaluation item into the evaluation item input unit 213 by hovering the pointer over the desired evaluation item in the pull-down menu 213a and selecting it using the input terminal. In this embodiment, in the example shown in FIG. 29(a), cutting resistance (maximum value) is input as the evaluation item in the evaluation item input unit 213.

Then, proceeding to step S16, the cutting edge condition display unit 214 displays the evaluation items of the cutting edge condition extraction data in the evaluation area along with the cutting edge shape. In this embodiment, in the example shown in Figure 29 (b), the cutting resistance (maximum value) in the evaluation area of the cutting edge shape selected by the user is displayed in the portion indicated by reference numeral 213b. The user can visually confirm the maximum cutting resistance indicated by reference numeral 213b, and even non-experts can easily determine whether or not damage will occur to the cutting edge of the tool. Note that even if the integrated value of cutting resistance is entered instead of the cutting resistance (maximum value) as the evaluation item, the integrated value of cutting resistance can be similarly visually confirmed, and even non-experts can easily determine whether or not damage will occur to the cutting edge of the tool. Note that although the cutting edge condition display unit 214 is separate from the integrated display unit 201 in this embodiment, it may be integrated with the integrated display unit 201.

Furthermore, the cutting edge condition display unit 214 may display the entire evaluation region of the cutting edge shape in a display format set based on the value of the cutting edge condition extraction data for the evaluation item. For example, in the example shown in FIG. 30(a), evaluation regions where the cutting resistance as an evaluation item is equal to or greater than a predetermined reference value are indicated by black circles in the portion indicated by reference numeral 213d, and evaluation regions where the cutting resistance is less than the predetermined reference value are indicated by open circles in the portion indicated by reference numeral 213c. Alternatively to the example in FIG. 30(a), in the example shown in FIG. 30(b), evaluation regions where the cutting resistance as an evaluation item is at its maximum value are indicated by black triangles in the portion indicated by reference numeral 213e, and evaluation regions where the cutting resistance is less than the maximum value are indicated by black dots. Although not shown, evaluation regions where the integrated value of cutting resistance as an evaluation item is at its maximum value may be indicated by black circles, and evaluation regions where the integrated value is less than the maximum value may be indicated by black dots. In either case, the maximum value or integrated value of cutting resistance can be visually confirmed, allowing even non-experts to easily determine whether or not damage will occur to the cutting edge of the tool. Note that the display format may be a different color instead of a black or white display format.

The cutting edge condition display unit 214 can also display time-series data along with the cutting edge shape and evaluation items. In the example shown in Figures 31 and 32, as shown in Figure 31, the display item 215a of the time-series data 215 can be selected from a pull-down menu (not shown), and cutting force time-series data 216 is displayed. The cutting force time-series data can be obtained based on the calculation results of the cutting force calculation unit 140 shown in Figure 1. Then, as shown in Figure 32, the user sets an arbitrary time t1 in the time setting unit 215b, and the time t1 is clearly indicated in the time-series data 215. The cutting edge shape at time t1 and the cutting depth value 213b are displayed on the XY coordinate plane 216 as evaluation items of the cutting edge condition extraction data in the evaluation area. In this case, the user can also visually confirm the value indicated by the symbol 213b, and even an unskilled user can easily determine whether or not damage will occur to the cutting edge of the tool.

5. Effects The vibration simulation device 1 of this embodiment first calculates an interference area between the tool 10 and workpiece 20 during gear-generating cutting based on the tool shape and workpiece shape defined based on the analysis conditions and the relative movement trajectory between the tool 10 and workpiece 20, and then calculates a cutting force to remove the interference area. Then, the relative dynamic characteristics or individual dynamic characteristics between the tool 10 and workpiece 20 are defined based on the analysis conditions, and the relative vibration between the tool 10 and workpiece 20 is calculated based on the cutting force and the dynamic characteristics. This makes it possible to predict vibrations at the processing point during gear-generating cutting with high accuracy.

Furthermore, the state of relative vibration occurrence is evaluated based on the calculation results of the vibration calculation unit 160 or the calculation results of the cutting force calculation unit 140 based on the frequency analysis results of the frequency analysis unit 191, and the evaluation results are displayed. By displaying the evaluation results in this way, the display content of the prediction results is improved so that the user can make effective use of them.

Furthermore, because the gear generating cutting process in this embodiment 1 involves cutting curved tooth flanks, the predicted results for the machined shape tend to be more complex than when machining flat surfaces, such as with an end mill, making it difficult for users to understand the predicted results. However, as described above, improvements have been made to the display of predicted results, allowing users to effectively utilize the predicted results for the machined shape and chatter vibrations in gear generating cutting processes that cut curved tooth flanks.

Furthermore, by displaying the cutting edge shape of the tool 10 along with the cutting edge condition extraction data for the evaluation item, even an unexperienced user can determine whether or not damage to the cutting edge of the tool 10 will occur, making it easier to determine whether the predicted machining results are possible.

In addition, this embodiment 1 includes a predicted tooth flank shape display unit 182 that displays a predicted tooth flank shape including data on the difference from the reference surface, with the tooth trace direction and tooth profile direction as display axes, based on the prediction results of the machining result prediction unit 181; a predicted tooth trace shape display unit 183 that displays the predicted tooth flank shape at a predetermined tooth profile direction position, with the tooth trace direction position and the difference from the reference surface as display axes; and a predicted tooth profile shape display unit 184 that displays the predicted tooth flank shape at a predetermined tooth trace direction position, with the tooth profile direction position and the difference from the reference surface as display axes, and an integrated display unit 201 that displays the display contents of the predicted tooth flank shape display unit 182, predicted tooth trace shape display unit 183, and predicted tooth profile shape display unit 184 at predetermined positions on a single screen. This makes it easier for the user to intuitively grasp the tooth flank shape, tooth trace shape, and tooth profile shape, and the display content of the prediction results has been improved to allow the user to effectively utilize the prediction results.

Furthermore, in this embodiment 1, the integrated display unit 201 can display the display contents of the vibration state display unit 193 at a specified position on the single screen. This makes it easier for the user to grasp the vibration state as well as the tooth flank shape, tooth trace shape, and tooth profile shape, and the display contents of the prediction results have been improved so that the user can make effective use of the prediction results.

In addition, this first embodiment further includes a display condition setting unit 200 that sets the display content to be displayed on the integrated display unit 201. This makes it possible to improve the display content of the prediction results so that the user can make effective use of the prediction results.

Furthermore, in this embodiment 1, the frequency analysis unit 191 outputs, as the frequency analysis result, a contour diagram obtained by performing a short-time Fourier transform on the time-series data of the calculation results of the vibration calculation unit 160 or the calculation results of the cutting force calculation unit 140. This makes it easier for the user to understand the vibration state.

Furthermore, in this embodiment 1, the frequency analysis unit 191 may output a scatter diagram obtained by fast Fourier transform as the frequency analysis result, instead of performing a short-time Fourier transform on the time-series data of the calculation results of the vibration calculation unit 160 or the calculation results of the cutting force calculation unit 140. Even in this case, the user can grasp the vibration state, and the same effect as in this embodiment 1 can be achieved.

In addition, in this embodiment 1, the vibration occurrence evaluation unit 192 evaluates the occurrence state of relative vibration based on the detection results of the cutting edge passing frequency component and the chatter vibration frequency component in the frequency analysis results of the frequency analysis unit 191. This makes it possible to predict with high accuracy whether chatter vibration will occur.

In addition, in this embodiment 1, the vibration state display unit 193 displays the frequency analysis results of the frequency analysis unit 191 in a frequency range that includes the cutting edge passing frequency component and the chatter vibration frequency component, with the machining time and frequency as the display axes. This allows the user to accurately grasp the vibration state.

Furthermore, in this embodiment 1, the cutting edge condition extraction data includes, as an evaluation item, at least the surface pressure calculated based on the calculation results of the cutting force calculation unit 140. This makes it easy to determine whether or not damage to the cutting edge of the tool 10 will occur.

Furthermore, in this embodiment 1, the cutting edge state extraction data includes, as an evaluation item, cutting resistance calculated based on at least the calculation results of the vibration calculation unit 160 and the calculation results of the cutting force calculation unit 140. This makes it easy to determine whether or not damage to the cutting edge of the tool 10 will occur.

Furthermore, in this embodiment 1, the cutting edge condition extraction data includes, as evaluation items, at least the rake angle or cutting depth calculated based on the calculation results of the interference area calculation unit 130. This makes it easy to determine whether or not damage to the cutting edge of the tool 10 will occur.

In addition, in this embodiment, the cutting edge condition display unit 214 displays cutting edge condition extraction data for evaluation items in a selected evaluation area from among the evaluation areas for the cutting edge shape. This allows the user to easily determine whether or not damage, etc. will occur in any area of the cutting edge of the tool 10.

Furthermore, in this embodiment, the cutting edge condition display unit 214 can display the entire evaluation area of the cutting edge shape in a display format set based on the value of the cutting edge condition extraction data for the evaluation item. This makes it easier for the user to visually recognize the cutting edge condition extraction data, allowing them to more easily determine whether or not damage will occur in any area of the cutting edge of the tool 10.

Furthermore, in this embodiment, the cutting edge condition display unit 214 can display, in a specific display format, the area within the evaluation area of the cutting edge shape where the cutting edge condition extraction data is at its maximum or minimum value, or the area where the integrated value of the cutting edge condition extraction data is at its maximum value. This makes it easier for the user to visually identify the area where the cutting resistance is at its maximum or minimum value, or the area where the integrated value of cutting resistance is at its maximum, and makes it easier to determine whether or not damage will occur in any area of the cutting edge of the tool 10.

Furthermore, the machining shape simulation device 100 of this embodiment is configured to use the cutting edge state extraction unit 212 to calculate cutting edge state extraction data during machining in multiple evaluation regions of the cutting edge shape based on at least the calculation results of the interference region calculation unit 130, display the cutting edge shape on the cutting edge state display unit 214 based on the model data stored in the cutting edge model storage unit 211, and display the evaluation items in the cutting edge state extraction data input to the evaluation item input unit 213 for the evaluation region of the selected cutting edge shape. This allows the user of the machining shape simulation device 100 to determine whether or not damage will occur in any region of the cutting edge of the tool 10, and to easily determine whether or not damage will occur to the tool 10.

As described above, according to the above aspect, it is possible to provide a machining shape simulation device 100 that can predict vibrations at the machining point during gear generation cutting with high accuracy, improves the display of the prediction results, and makes it easy to determine whether machining is possible.

In this first embodiment, tooth surface quality evaluation and chatter vibration evaluation are performed after machining is completed, but instead, tooth surface quality evaluation may be performed each time the workpiece shape is updated, and chatter vibration evaluation may be performed each time the relative vibration or cutting force is calculated.

This disclosure is not limited to the above-described embodiments and can be applied to various embodiments without departing from the spirit of the present disclosure.

Claims (15)

1. A machined shape simulation device that simulates a machined shape of a gear based on relative vibration between a tool and a workpiece in gear-generating cutting, in which a cutting process is performed on a workpiece with a tool to generate a gear, comprising:
a shape defining unit that defines a tool shape and a workpiece shape based on analysis conditions including tool specifications, workpiece specifications, and machining conditions;
a cutting edge model storage unit that stores model data of a cutting edge shape in the tool shape;
an interference area calculation unit that calculates an interference area between the tool and the workpiece during gear generating cutting, based on the tool shape, the workpiece shape, and relative movement trajectories of the tool and the workpiece;
a cutting force calculation unit that calculates a cutting force when the tool removes the interference region from the workpiece;
a dynamic characteristic defining unit that defines relative dynamic characteristics or individual dynamic characteristics between the tool and the workpiece based on the analysis conditions;
a vibration calculation unit that calculates the relative vibration between the tool and the workpiece based on the cutting force and the relative dynamic characteristics;
a machining result prediction unit that predicts a machining result of the workpiece based on a vibration simulation result including the relative vibration repeatedly calculated by the interference region calculation unit, the cutting force calculation unit, and the vibration calculation unit;
a frequency analysis unit that performs frequency analysis on the calculation result of the vibration calculation unit or the calculation result of the cutting force calculation unit;
a vibration generation evaluation unit that evaluates a generation state of the relative vibration based on a frequency analysis result of the frequency analysis unit;
a vibration state display unit that displays the evaluation result of the vibration generation evaluation unit;
a cutting edge state extraction unit that extracts cutting edge state extraction data during machining in a plurality of evaluation regions of the cutting edge shape based on at least the calculation result of the interference region calculation unit;
an evaluation item input unit for inputting evaluation items in the cutting edge state extraction data;
a cutting edge state display unit that displays the evaluation items of the cutting edge state extraction data in the evaluation area together with the cutting edge shape;
A machining shape simulation device comprising: a predicted tooth flank shape display unit that displays a predicted tooth flank shape including data on a difference from a reference surface, with the tooth trace direction and the tooth profile direction as display axes based on the prediction result of the machining result prediction unit;
a predicted tooth trace shape display unit that displays a predicted tooth trace shape at a predetermined tooth profile direction position, using a difference between a tooth trace direction position and a reference plane as a display axis;
a predicted tooth profile shape display unit that displays a predicted tooth flank shape at a predetermined tooth trace direction position, using a tooth profile direction position and a difference from a reference surface as a display axis;
an integrated display unit that displays the display contents of the predicted tooth flank shape display unit, the predicted tooth trace shape display unit, and the predicted tooth profile shape display unit at predetermined positions on one screen;
The machining shape simulation device according to claim 1 , comprising: The machining shape simulation device of claim 2, wherein the integrated display unit displays the display contents of the vibration state display unit at a predetermined position on the single screen. The machining shape simulation device of claim 3, further comprising a display condition setting unit that sets the display content to be displayed on the integrated display unit. The machining shape simulation device according to any one of claims 1 to 4, wherein the frequency analysis unit outputs, as the frequency analysis result, a contour diagram obtained by performing a short-time Fourier transform on the time-series data of the calculation results of the vibration calculation unit or the calculation results of the cutting force calculation unit. The machining shape simulation device according to any one of claims 1 to 4, wherein the frequency analysis unit outputs, as the frequency analysis result, a scatter diagram obtained by performing a fast Fourier transform on the time-series data of the calculation results of the vibration calculation unit or the calculation results of the cutting force calculation unit. The machining shape simulation device according to any one of claims 1 to 4, wherein the vibration generation evaluation unit evaluates the occurrence state of the relative vibration based on the frequency analysis results of the frequency analysis unit, the cutting edge passing frequency component calculated based on the tool specifications, and the detection results of the chatter vibration frequency component calculated based on the determination results of the dynamic characteristics determination unit. The machining shape simulation device of claim 7, wherein the vibration state display unit displays the frequency analysis results of the frequency analysis unit in a frequency range including the cutting edge passing frequency component and the chatter vibration frequency component, with machining time and frequency as display axes. The machining shape simulation device according to any one of claims 1 to 4, wherein the cutting edge condition extraction data includes, as an evaluation item, at least a surface pressure calculated based on the calculation results of the cutting force calculation unit. The machining shape simulation device according to any one of claims 1 to 4, wherein the cutting edge state extraction data includes, as evaluation items, cutting resistance calculated based on at least the calculation results of the vibration calculation unit and the calculation results of the cutting force calculation unit. The machining shape simulation device according to any one of claims 1 to 4, wherein the cutting edge condition extraction data includes, as the evaluation items, at least the rake angle or cutting depth calculated based on the calculation results of the interference area calculation unit. The machining shape simulation device described in any one of claims 1 to 4, wherein the cutting edge condition display unit displays the cutting edge condition extraction data for the evaluation item in a selected evaluation area from among the evaluation areas for the cutting edge shape. The machining shape simulation device described in any one of claims 1 to 4, wherein the cutting edge condition display unit displays the entire evaluation area of the cutting edge shape in a display format set based on the value of the cutting edge condition extraction data for the evaluation item. The machining shape simulation device described in any one of claims 1 to 4, wherein the cutting edge condition display unit displays, in a specific display format, the area within the evaluation area of the cutting edge shape where the cutting edge condition extraction data has a maximum or minimum value, or the area where the integrated value of the cutting edge condition extraction data has a maximum value. The cutting edge state extraction unit extracts the cutting edge state extraction data based on at least the calculation result of the interference region calculation unit,
The cutting edge shape is displayed on the cutting edge state display unit based on the model data stored in the cutting edge model storage unit,
The machining shape simulation device according to any one of claims 1 to 4, wherein the cutting edge state display unit is configured to display evaluation items in the cutting edge state extraction data inputted to the evaluation item input unit for an evaluation region of the selected cutting edge shape.