JP2002014711A - Method for searching uncut corner processing area for contour line processing and method for creating uncut corner processing area using the method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the amount of data when obtaining a tool trajectory in the next process, to simplify the calculation process, and to shorten the processing time in the next process. SOLUTION: In search of a machining range of the uncut corner in order to create a tool trajectory in a next process for performing contour line processing with a tool having a different rounding radius at the tip of the remaining uncut corner in the previous process, an uncut portion is searched. The cross-sectional shape of the tool is represented by the combination of arcs or a combination of arcs and straight lines, and for the tool height of each layer in the next process corresponding to each layer in the previous process, the cross-sectional shape of the tip of the tool in the next process is a combination of arcs or The position that contacts the cross-sectional shape of the uncut portion represented by the combination of the arc and the straight line is the contact position of the tool in the next process with the uncut portion, and the tool in the next process contacts the product shape from the contact position The tool at the tool position where the travel distance to the position is calculated, the travel distance is set as the expected distance, and the contact position of the tool in the next process to the uncut portion is offset to the product shape side by the estimated distance. The existence range of the region surrounded by the trajectory and the tool trajectory at the position where the tool of the next process comes into contact with the product shape is left uncut and used as the corner machining range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of searching for a machining range of an uncut corner for contour line machining, which is suitable for use in producing NC (numerical control) data for a CAM (computer assisted machining) system. Further, the present invention relates to a method of creating a remaining machining area at the corner portion using the method.

[0002]

2. Description of the Related Art When shaping a die or the like from a block-shaped material using a CAM (Computer Aided Machining) system, a relatively large-diameter tool is generally used to shorten the machining time. Rough cutting is used to cut the material to near the product shape (finished shape), and then finish processing the product shape to finish. Prevention of problems such as tool breakage by constant machining.

[0003] As a method of such rough machining, for example, Japanese Patent Application Laid-Open No. 8-155788 discloses a so-called one-shot machining in which cutting is performed sequentially from above to below at a large step corresponding to a considerable portion of a tool length. A tool that performs large rough machining and the so-called semi-rough machining, in which each step of the step-shaped intermediate shape after the large rough machining is sequentially cut from the bottom to the top with a smaller step than the large rough machining. A roughing method that makes effective use of the length has been proposed. In this method,
Since a tool that has a tip with almost no rounded corners, such as a flat end mill or square end mill, is used, the intermediate shape after large rough machining in the previous process becomes a step-like shape, so the middle between the tool path and the tool diameter It was possible to express the shape, determine the tool trajectory for the next rough machining from the shape, and create NC data for the middle rough machining from the tool trajectory.

In recent years, as a roughing method, a large area tool such as a face mill or a radius end mill having a large bottom area is used at once to process a large area using the large bottom area. It has been studied to perform medium-rough machining on uncut parts in large-rough machining with tools smaller in diameter than the tools used in.

[0005]

However, unlike the flat end mill and the square end mill, large-diameter tools such as the face mill and the radius end mill described above have a tip portion for preventing an excessive processing load on the tool. Has a relatively large radius (corner R) at the corner, the cross-sectional shape of the intermediate shape after machining with the large-diameter tool becomes a shape combining a straight line and a circular arc, and this results in large rough machining. The subsequent intermediate shape cannot be simply represented by the tool path and the tool diameter, but must be represented by three-dimensional shape data capable of expressing a curved surface. When calculating the tool trajectory for machining, the amount of data becomes enormous and the calculation process becomes complicated.
There is a problem that the process for creating data takes time.

In order to solve the above-mentioned problem, it is conceivable to use a method as disclosed in, for example, Japanese Patent Application Laid-Open No. 8-123527. That is, first, from the tool path closest to the product shape of the large-diameter tool for large-diameter machining in the previous process and the round shape of the outer diameter and the tip of the large-diameter tool, the large-diameter tool positioned on the tool path is determined. Obtain the outer shape, and cut the outer shape of the large-diameter tool in a number of planes arranged in the tool axis direction at a pitch small enough to approximate the rounded shape of the tip of the large-diameter tool in the direction perpendicular to the tool axis. The process of determining the tool cross-sectional shape, and further cutting the tool cross-sectional shape on a plane orthogonal to the tool trajectory to obtain the tool external points located on the plurality of planes, is performed for each layer of the rough machining. Is performed while moving the position of the large-diameter tool along the tool trajectory to create tool outlines which are trajectories of the tool outline points on the plurality of planes, respectively. Line If standing than joining together by cutting a portion closer to the product shape, representing an intermediate shape after Oara processing large 径工 tool by a line on the multiple planes.

[0007] Next, regarding the outer shape of the tool for the intermediate rough machining in the next step, the tool cross-sectional shape is obtained by cutting each of the above-mentioned many planes, and the tool cross-sectional shape is the intermediate shape on the same plane. The trajectory of the tool center position when moving while contacting the line of each is obtained, and the trajectory of the tool center position is projected on one plane extending in a direction orthogonal to the tool axis, and the tool By cutting out and joining the parts of the trajectory that are farthest from the product shape, the tool trajectory when the medium-rough machining tool moves while touching the intermediate shape after large-rough machining without touching it is calculated. Calculate the tool trajectory of the entire middle roughing by using this.
However, even in such a case, the amount of data when calculating the tool trajectory for the rough machining in the next process is still enormous, the arithmetic processing is complicated, and the processing for creating NC data takes time. There was a problem.

Further, in the above-mentioned rough machining using the large-diameter tool, since the tool diameter is large, the radius of curvature of the product shape is smaller than the tool radius in the intermediate shape in each layer of the contour line processing, so that the tool cannot be completely inserted and the uncut portion remains. There will be many uncut corners, which are corners where this occurs, and this means that in the next step, these uncut corners will be removed by a tool with a smaller diameter than the large-diameter tool as described earlier. It is considered to perform medium roughing.
For the purpose of increasing the processing efficiency and reducing the uncut portion in the middle roughing, it has been studied to perform contour line processing with a large diameter tool for large roughing and a tool with a different radius at the tip. If the tip has a different radius of radii, there will be a narrow processing area for each layer of the contour line processing of the medium and rough processing, even in the above-mentioned non-remaining corners.

However, if the narrow processing area is to be subjected to medium roughing, even if the medium rough processing is performed, the final required finish will not be obtained. As a result, there is a problem that useless time for rough machining is generated.

[0010]

SUMMARY OF THE INVENTION The present invention advantageously solves the above-mentioned problems and provides a method for searching for a remaining machining area for contour line machining and a method for creating an unmachined corner machining area using the method. It is an object of the present invention to provide a method for searching a remaining machining area for contour line machining according to claim 1 of the present invention, the method comprising: In order to create a tool path in the next step of performing contour line processing with a tool having a different radius of radii at the tip and at the time of searching for a processing range of the uncut corner, the cross-sectional shape of the uncut part in the previous step is searched. Based on the cross-sectional shape of the rounded tip of the tool of the preceding process located on the tool path closest to the product shape in each layer of the contour processing in the preceding process, a combination of arcs or an arc and a straight line The tool height of each layer of the contour processing of the next step corresponding to each layer of the contour processing of the previous step, the cross-sectional shape of the rounded tip of the tool of the next step is represented by a combination of the arcs. Obtain a position that contacts the cross-sectional shape of the uncut portion in the previous process represented by a combination or a combination of an arc and a straight line, and that position as the contact position of the tool in the next process with respect to the uncut portion,
From the contact position of the tool in the next step with the uncut portion, determine the movement distance from the contact position of the tool in the next step to the product shape, the movement distance as the expected distance, the uncut portion The contact position of the tool in the next step with respect to the product shape side by the expected distance, the tool path based on the position where the tool in the next step contacts the product shape, and the offset tool position A range in which a region surrounded by the tool trajectory is present is obtained, and the range is left uncut and used as a corner processing range.

According to the method for searching for the uncut corner processing area for contour line machining, the cross-sectional shape of the uncut portion in the previous step is positioned on the tool path closest to the product shape in each layer of the contour line processing in the previous step. Based on the cross-sectional shape of the rounded tip of the tool in the previous process, it is expressed by a combination of arcs or a combination of an arc and a straight line, and each layer of the next process contour processing corresponding to each layer of the previous process contour processing Regarding the tool height, the position where the cross-sectional shape of the rounded tip of the tool in the next process touches the cross-sectional shape of the uncut portion in the previous process expressed by a combination of arcs or a combination of arcs and straight lines From the intermediate shape represented by the three-dimensional shape data and the intermediate shape represented by a number of lines on the plane. It is not necessary to determine the ingredients trajectory, and obtained by the arithmetic processing with may reduce the data amount for obtaining the tool path a next step easily, NC data can be finished in a short time a process for creating.

In addition, a moving distance from the contact position of the tool in the next process to the uncut portion to the position where the tool in the next process contacts the product shape is determined, and the moving distance is set as an expected distance, and The contact position of the tool in the next process with respect to the remaining portion is offset toward the product shape by the estimated distance, the tool path based on the position where the tool in the next process contacts the product shape, and the tool based on the offset tool position By obtaining the range where the area surrounded by the trajectory exists and setting the range as the uncut corner processing area, the offset processing can delete the narrow processing area of the part other than the uncut corner. , It is possible to accurately search for the uncut corners from the intermediate shape after the previous process with a large diameter tool, and create a machining area for the next process by corresponding only to the uncut corners, The stomach is able to eliminate the processing time of useless the next step.

[0013] In the method of searching for the uncut corner processing area for contour line processing according to the present invention, as described in claim 2, the tool height of each layer of the contour line processing in the next step is the most suitable for the product shape. The maximum value of the moving distances determined along the close tool path may be set as the estimated distance. In this case, the estimated distance can be set to a constant value, and the process of searching for the uncut corners can be simplified. In addition, it can be done in a short time, and by adopting the maximum value, the range of the uncut corner can be minimized.

According to a third aspect of the present invention, there is provided a method for creating a left-behind corner processing area according to the first or second aspect of the present invention, wherein
For the tool height of each layer of the contour processing in the next step, for the uncut corner processing area, a tool path based on the position where the tool in the next step contacts the product shape, and the tool in the next step A region surrounded by a tool trajectory based on a position where the uncut portion is contacted is determined, and the region is set as a non-cut corner processing region.

According to the method for creating an uncut corner processing area, the tool based on the position at which the tool in the next process comes into contact with the product shape with respect to the uncut corner processing area obtained by the accurate search by the above method. The area surrounded by the trajectory and the tool trajectory based on the position at which the tool of the next process contacts the uncut portion is obtained, and the area is set as the uncut corner processing area. The NC data can be accurately removed from the corner machining area by leaving the narrow machining area uncut, so that only the uncut corner machining area is machined in the next process for the intermediate shape after the previous process with the large-diameter tool. By creating, the man-hour for creating the next process NC data can be reduced, and unnecessary processing time of the next process can be eliminated.

In the method for creating an uncut corner processing area according to the present invention, the tool locus closest to the product shape with respect to the tool height of each layer in the contour line processing in the next step is described in claim 4. The slope of the product shape of the inclination angle at which the minimum value of the moving distances obtained along is obtained as the representative slope, and the representative uncut corner may be obtained as the product shape with the representative slope as the corner processing area. By doing so, the tool trajectory based on the position where the tool in the next process contacts the product shape can be simplified by offsetting the product shape at the tool height of each layer in the next process by a fixed distance. The tool contact position can be determined in a short time, and the tool contact position can be determined by using the representative slope with the steepest inclination angle at which the minimum value can be obtained as the product shape. It is possible to reliably eliminate.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a flow chart showing a processing procedure of an embodiment of a method for creating a left-behind corner processing area according to an embodiment of the present invention, which uses an embodiment of a method for searching a remaining-cut corner processing area for contour line processing according to the present invention. FIG. 2 is a flowchart showing a method for creating a tool path for rough machining using the method for creating an uncut corner machining area according to the above-described embodiment. This is used to create NC data for rough machining of a mold part with a CAM system.
N using an ordinary computer that constitutes the M system
In the C data creation device, the operation program is implemented by appropriately modifying the operation program.

The method of creating the tool path for rough machining shown in FIG. 2 will be briefly described. In this method, the tool axis directions of large rough machining and medium rough machining are set in the vertical direction (vertical direction) in advance, and While a face mill with a round piece tip at the corner of the tip is used as a large diameter tool for large rough machining, a ball end mill with a smaller diameter than the face mill and a hemispherical tip is used as a small diameter tool for medium rough machining. It is set to be used, and furthermore, each layer (each tool tip height) of contour line machining of large rough machining and contour line machining of medium rough machining is set. In the following description, for the sake of easy understanding, it is assumed that each layer of the contour processing of the medium rough processing corresponds to each layer of the contour processing of the large rough processing. The heights may be different and may correspond one-to-one, or a plurality of layers may correspond to each layer of the contour processing of the rough processing.

In this method, first, in step 11,
The computer of the NC data generating apparatus described above uses three-dimensional data representing the product shape (finished shape) of each layer of the contouring process of the rough machining set as described above (the product three-dimensional shape is a set of many points in a three-dimensional coordinate system). The so-called CAM data or so-called CAD data in which the product three-dimensional shape is expressed by a mathematical expression such as a curved surface in a three-dimensional coordinate system) is cut along a horizontal plane, and the contour lines of the product shape are calculated. Then, in step 12, the user of the computer defines the material shape by inputting the material shape into the computer.

In the following step 13, the contour line of the product shape is offset by the above-mentioned computer for each layer of the contour machining of the rough machining by the radius of the tool for the rough machining, and the tool for the product shape when a square end mill is used as the tool. Of the product shape surface between each layer and the layer above it from the horizontal pitch between the contour lines of the product shape of each layer of the rough machining contour and the layer above it. The angle of inclination with respect to the vertical plane is determined, and the contact position of the large roughing tool with respect to the product shape is determined using the square end mill according to the angle of inclination, the tool diameter of the rough roughing tool, and the round radius of the tool tip. The tool trajectory of each layer of large rough contour machining from the corrected tool contact position on each layer and the material shape defined above From the tool trajectory for large rough machining, NC data for large rough machining is created, and as described later, an intermediate shape after rough machining represented by a combination of arcs or a combination of arcs and straight lines is calculated. Ask.
Note that the tool trajectory in each layer of the contour processing of the rough machining may be obtained by using another conventionally known method such as performing contact calculation between the product three-dimensional shape and the tool three-dimensional shape for each layer.

Next, here, in step 14, for each layer of the contouring process of the above-mentioned medium rough machining, the three-dimensional data of the product shape is cut by a horizontal plane by the computer to calculate a contour line of the product shape. Then, in step 15, by the above-mentioned computer, the intermediate shape after the large rough processing determined in step 13, the contour contour of the product shape for each layer of the contour processing of the medium rough processing determined in step 14, and From the tool diameter of the tool for roughing and the radius of the tip of the tool as described below, the uncut corner processing area as the medium roughing area is calculated (created) as described later. By the above-mentioned computer, a tool trajectory for medium rough machining for machining only the uncut corner machining area as the medium rough machining area is obtained by calculation using a conventionally known method, and the medium rough machining is performed. NC data for medium roughing is created from the tool trajectory.

As shown in FIG. 3 (a), using the tool trajectory for large rough machining created by the above method, a large diameter for large rough machining having a plurality of round piece chips CC at the tip corner at equal intervals in the circumferential direction. When the face mill FM as a tool is moved so that the tool axis CF moves on the tool path TP for large rough machining, contour machining for large rough machining is performed, and from the material shape M to the product shape (finished shape) FF. Until then, large rough machining utilizing the width of the tip surface of the large diameter tool is performed. Note that arrows CD, PD, and RD for the face mill FM in FIG. 3 and subsequent figures indicate a machining progress direction, a pitch (drive-in) direction, and a rotation direction of the tool, respectively. FIG. 3 (b) shows an intermediate shape IF after the rough machining, and the intermediate shape IF has a substantially stepped shape as a whole, and each layer of the rough machining, as shown in FIG. 3 (c). Since the radius of curvature of the contour line of the product shape (finished shape) FF is smaller than the tool radius of the face mill FM, a portion of the tool path TP where the face mill FM cannot fully fit is left off. In the present specification, the portion which has a small radius of curvature and is not cut by the face mill FM and is left uncut is referred to as a left uncut corner RN.

Next, for the intermediate shape IF after the above-mentioned large rough machining, using the tool trajectory for the medium rough machining created by the above method, it is shown in FIG. 4 (a) and each layer of the medium rough machining is shown in FIG. 4 (b). As shown, the ball end mill BM as a small-diameter tool for small-diameter roughing than the face mill FM
Is moved so that the tool axis CB moves on the tool path TP for the above-mentioned middle rough machining, and contour machining of the middle rough machining is performed.
The uncut corners RN of each layer of the middle rough machining from the above-mentioned intermediate shape IF are cut away to form a shape MF after the middle rough machining closer to the finished shape FF as shown in FIG.

By the way, in steps 13 to 15 of the above-described method for creating a tool path for rough machining, in each of the remaining uncut corners in the contour machining of the large rough machining as the previous process, the medium rough machining as the next process of the rough machining is performed. In order to create a tool trajectory TP for performing contour line machining with the face mill FM for large rough machining and the ball end mill BM having a different radius at the tip end, the uncut corner machining area of the embodiment shown in FIG. In the method for creating an uncut corner processing region in this embodiment, first, in step 1, the shape of the uncut portion in the large rough machining is used to search for the uncut corner. The cross-sectional shape of the shape IF is as shown in FIG.
Based on the cross-sectional shape of the rounded tip of the face mill FM of the face mill FM located on the tool path closest to the product shape in each layer of the contour machining of the rough machining, a combination of multiple arcs or , One or more arcs and straight lines. In FIG. 5, PD is the pitch direction of the tool movement, P is the pitch of the tool path, CF1 is the tool axis on the tool path one pitch before the tool path closest to the product shape, and CF2 is the closest to the product shape. The tool axis on the tool path is shown.

FIGS. 6 (a) and 6 (b) show differences in the cross-sectional shape of the intermediate shape IF, which is the shape of the uncut portion in the above-mentioned rough machining, due to the inclination angle of the surface of the product shape. As shown in FIG. 6 (a), for the intersection CP between the arc of the tool roundness (end R) of the target layer and the contour line of the upper layer, the tool roundness (end R) of the layer immediately above it The case where the center RC of the arc in ()) is on the product shape FF side is referred to as “when the inclination angle is gentle”, and in this case, the cross-sectional shape is represented by a combination of a contour straight line of each layer and a tool round arc. Also, as shown in FIG. 6B, the intersection of the circular arc of the tool roundness (end R) of the target layer and the contour line of the layer immediately above the intersection CP of the upper layer tool roundness (end R). The case where the center RC of the arc is on the side opposite to the product shape FF is called `` when the inclination angle is steep '', and in this case, the cross-sectional shape is represented by a combination of arcs of tool roundness except for the bottom layer,
The intersection of the arcs is located at a height slightly off the contour line of each layer. In addition, whether the inclination angle is gentle or steep depends on the interlayer pitch (thickness of each layer) of the rough processing and the product shape.
It is determined by the position of the circular arc of the tool roundness of the face mill FM located on the tool path closest to the product shape of each layer and the radius of the circular arc.For example, even at the same interlayer pitch and circular arc position, if the circular arc radius is large, the circular arc If the arc crosses each other and the inclination angle is steep, if the radius of the arc is small, the arc and the straight line of the upper layer may intersect and the inclination angle may be gentle.

Next, here, in step 2, first, the uppermost layer of the plurality of layers of the contour machining of the medium rough machining is selected as the target layer, and in step 3, the ball end mill, which is a small-diameter tool for the medium rough machining, is selected. The position where the BM contacts the cross-sectional shape of the intermediate shape IF, which is the shape of the uncut portion of the target layer in the rough machining, that is, the processing start position is determined by geometric calculation. Here, when the arc of the tool roundness of the ball end mill BM is larger than the radius of the tool round of the face mill FM, and when the inclination angle of the cross-sectional shape is gentle as shown in FIG. The position where the ball end mill BM comes into contact with the cross-sectional shape of the intermediate shape IF after the roughing is the arc of the external shape of the ball end mill BM that is in contact with the contour line of the target layer (the second layer from the bottom in the example shown) of the medium roughing However, the tool round arc of the face mill FM located on the tool path closest to the product shape in the layer of large rough machining corresponding to that layer (in the example shown, the layer with the same height as the medium rough machining) and one higher This is the position that is in contact with the intersection CP1 with the contour line of the rough processing layer. Therefore, FIG.
As shown in (b), the tool axis of the face mill FM is CF,
CB is the tool axis of the ball end mill BM, r is the radius of the tool round of the face mill FM, r is the radius of the tool round of the ball end mill BM, t is the pitch in the Z direction (interlayer pitch) for rough machining, and t is the ball end mill BM. Intersection point with tool axis CB
X ₁ horizontal distance between the CP1, the horizontal distance between the arc center position and the intersection point CP1 of the tool round the face mill FM x
_2, when the correction amount indicating the arc center position between the horizontal distance of the tool round the ball end mill BM and face mill FM and AM,
The following equation (1) holds. The outside diameter of the face mill FM is D.

[0027]

(Equation 1) Here, SQRT represents a square root.

By using the correction amount AM and the outer diameter D of the face mill FM, the position of the tool axis CF of the face mill FM, that is, the tool trajectory of the rough machining, and the tool round arc radius of the ball end mill BM and the face mill FM are used. Then, the position of the tool axis CB of the ball end mill BM when it comes into contact with the cross-sectional shape of the uncut portion in the rough machining is determined.

On the other hand, this is a case where the radius of the tool round of the ball end mill BM is larger than the radius of the tool round of the face mill FM, and as shown in FIG. In this case, the position at which the ball end mill BM contacts the cross-sectional shape of the intermediate shape IF after the roughing is determined by the position of the ball end mill BM that is in contact with the contour line of the target layer (the lowest layer in the illustrated example) of the medium roughing. The arc of the outer shape is the tool round arc of the face mill FM located on the tool path closest to the product shape in the layer of large rough machining corresponding to that layer (in the example shown, the layer of the same height as the medium rough machining) Intersection CP2 with the face mill FM's tool round arc located on the tool path closest to the product shape in the next higher roughing layer, or between the face mill FM's tool round arcs in the upper layer At the intersection of Therefore, the contact position is the intersection CP2
In the case of, as shown in FIG. 8 (b), the arc center position OA of the tool roundness of the face mill FM on the target layer is set to the origin (0, 0).
Is set in the partial coordinate system xy, the pitch in the Z direction of the rough machining is t, and the arc center position OB of the tool roundness of the face mill FM in the upper layer is coordinate (x ₃ ,
t), the arc radius of the tool round of the face mill FM is r, the radius of the tool round of the ball end mill BM is R, and the arc center position OC of the tool round of the ball end mill BM on the target layer is coordinated in the above partial coordinate system ( x ₄ , R−r), the following relational expression shown in [Equation 2] holds. Here, the outside diameter of the face mill FM is also D.

[0030]

(Equation 2)

When the above relational expressions are simultaneously used and the outer diameter D of the face mill FM is used, the intersection CP2 is calculated from the tool axis position of the face mill FM, that is, the tool trajectory of the large rough machining, from the cross-sectional shape of the uncut portion in the large rough machining. The position of the tool axis CB of the ball end mill BM at the time of contact can be obtained, and the position of the tool axis CB of the ball end mill BM at the upper layer can be obtained in the same manner.

Next, here, in step 4, as shown in FIG. 9, the ball end mill BM of medium rough machining comes into contact with the cross-sectional shape of the intermediate shape IF which is the shape of the uncut portion of the face mill FM of large rough machining. From the contact position (the position shown on the right side in the figure) obtained in step 3 above, the ball end mill
The moving distance to the position where the BM comes into contact with the product shape FF (the position shown on the left side in the figure) is obtained, and the moving distance is set as the estimated distance AD. Here, as shown in FIG.
Ball end mill centered around the center of the circle of the tool center of the face mill FM with the circle A of the tool roundness of the center of the circle OA, B as the center of the circle of the center of the circle with the center of the arc
Assuming that the circle of the tool roundness of BM is C, the position and the inclination angle of the surface of the product shape FF are the straight line L1 passing through the arc center positions OA and OB.
Of the arc center position OC, which is also the center position of the ball end mill BM when the ball end mill BM comes into contact with the product shape FF because it corresponds to the position and inclination angle of
Coordinates x ₄ can be obtained by a relational expression shown in the following Formula 3. Note that the y coordinate of the arc center position OC is Rr
Is determined by

[0033]

(Equation 3)

Here, the estimated distance AD does not change depending on whether or not the corner is left uncut, but changes with a change in the inclination angle of the product shape. However, if the estimated distance AD is determined in accordance with the change in the inclination angle of the product shape, it takes a long time to search for the uncut corners described later. Therefore, in this embodiment, the maximum value of the estimated distance AD corresponding to the portion where the inclination angle of the product shape is the least in the target layer of the medium roughing is obtained, and the maximum value is subjected to the subsequent processing for the layer. Is a constant value of the expected distance AD.

Next, here, in step 5, first, the correction amount AM of the tool contact position of the medium rough machining obtained in step 3 above.
From the tool trajectory of the rough machining and the tool trajectory of the rough machining, a tool trajectory at a position where the ball end mill BM comes into contact with the intermediate shape IF which is the shape of the uncut portion of the rough machining in the target layer of the medium rough machining is obtained. However, the tool trajectory remains intact at all positions, and the tool trajectory at the position where the ball end mill BM contacts the product shape has a rough machining area with a width corresponding to the expected distance according to the preceding inclination angle. Therefore, the tool trajectory at the position where the ball end mill BM comes into contact with the uncut portion in the above-mentioned rough machining is then calculated as the estimated distance of the constant value.
Offset to product shape side by AD.

In the following step 6, a plan view of FIG. 11 and UU in FIG.
As shown in the cross-sectional views of FIGS. 12A and 12B along the line V-V and the line V-V, respectively, the tool path TP2 at the position where the ball end mill BM contacts the product shape, and the tool path of the rough machining The existence area on the tool path TP3 of the area surrounded by the tool path TP3 at the tool position where TP1 is offset to the product shape side by adding the above-mentioned correction value AM to the expected distance AD of the fixed value is geometrically expressed. It is determined by calculation, and the extended range of the enclosed region is left uncut and is set as the corner processing range. This makes it possible to determine the uncut corner processing area corresponding to the uncut corner RN of the product shape.

In the next step 7, as shown by the hatched area in FIG. 11, the uncut corner processing area NM for the middle roughing by the ball end mill BM with respect to the uncut corner processing area obtained in the step 6. Is calculated. That is, here, the tool trajectory TP1 of the rough machining in the range corresponding to the uncut corner processing range of the tool trajectory TP3 was obtained by offsetting the correction amount AM to the product shape side except for the expected distance AD, The tool path TP4 and the tool path TP3 at the position where the ball end mill BM comes into contact with the uncut part in rough machining
Tool trajectory at the position where the ball end mill BM contacts the product shape in the range corresponding to the above uncut corner machining area
TP2 and an area surrounded by a straight line connecting the edges of the tool trajectories TP4 and TP2 adjacent to each other are determined, and the area is defined as the uncut corner processing area NM, so that the uncut corner processing is performed. Create an area NM.

In this embodiment, when creating the above-mentioned uncut corner processing region NM, the inclination angle of the product shape at which the minimum value of the correction amount AM of the tool trajectory TP1 of the rough machining is obtained in the target layer. The slope at the steepest point where the inclination angle is equal to the straight line L1 in FIG. 10) is taken as the representative slope, and the correction amount AM of the tool trajectory TP1 of the rough machining on the representative slope, that is, the minimum value that is a fixed value, Offset the entire tool path TP1 for rough machining.

Further, in this embodiment, the ball end mill BM comes into contact with the uncut portion in the large rough machining, which is used in the above step 7 and offsets the tool trajectory TP1 of the large rough machining toward the product shape by the correction amount AM. As the tool path TP3 at the tool position (the position of the tool axis), the plan view in FIG.
14 along the line WW and line XX in FIG.
As shown in the cross-sectional views of (a) and (b), the product shape of the tool position when the ball end mill BM at the tool height of the target layer comes into contact with each layer of the medium roughing contour line above it Select the tool that connects the tool positions furthest from.

That is, for example, in the cross section of FIG. 14A along the line WW in FIG. 13, the tool path TP5 connecting the tool position when contacting the layer immediately above the target layer is different from the product shape. Since it is the farthest, the tool path TP5 is selected, and X in FIG.
-In the cross section of FIG. 14 (b) along the X-ray, since the tool path TP4 connecting the tool positions at the time of contacting two layers above the target layer is farthest from the product shape, the tool path TP4 is selected. .
Accordingly, it is possible to reliably prevent the ball end mill BM from cutting into the uncut portion in the large rough machining at the processing start position of the uncut corner processing region NM in the target layer. The tool path TP2 in FIGS. 13 and 14 indicates the tool path at the tool position (the position of the tool axis) where the ball end mill BM contacts the product shape FF.

After the uncut corner processing area NM is created as described above, in the next step 8, the next lower layer is selected by the contour line of the medium rough processing, and in the subsequent step 9, the lower layer is selected. It is determined whether or not exists, and if the layer exists, the process returns to the step 3 to repeat the above-described processing. If the layer does not exist, that is, if the above-described processing has been performed up to the lowermost layer of the medium rough machining Ends the processing in FIG. 1 and proceeds to step 16 in FIG.

Thus, according to the method of the above embodiment, the cross-sectional shape of the intermediate shape IF, which is the shape of the uncut portion in the rough machining, is set on the tool path closest to the product shape in each layer of the contour machining in the rough machining. Based on the cross-sectional shape of the rounded tip of the face mill FM, which is a tool for large rough machining, it is expressed as a combination of arcs or a combination of arcs and straight lines, and it is a medium rough machining corresponding to each layer of large contour machining For the tool height of each layer of contour line machining, the cross-sectional shape of the rounded tip of the ball end mill BM, which is a tool for medium rough machining, after rough machining expressed by a combination of arcs or a combination of arcs and straight lines The position of contact with the cross-sectional shape of the intermediate shape IF is obtained, and the position is used as the contact position of the ball end mill BM with respect to the uncut portion, so that the position is expressed by three-dimensional shape data. Since it is not necessary to determine the tool trajectory for middle roughing from the intermediate shape or the intermediate shape represented by a number of lines on a plane, it is possible to reduce the amount of data when calculating the tool trajectory for middle roughing and to simplify the calculation process. Get,
The processing for creating the NC data for medium rough machining can be completed in a short time.

Further, from the contact position of the ball end mill BM with the uncut portion, the ball end mill BM
Determine the moving distance to the position where it contacts the product shape, the moving distance is the estimated distance AD, and the contact position of the ball end mill BM with respect to the uncut portion is offset toward the product shape by the estimated distance AD, The tool path at the position where the ball end mill BM contacts the product shape,
The range in which the area surrounded by the tool path at the offset tool position exists is obtained, and the range is set as the uncut corner processing area. It is possible to delete the narrow machining area, accurately search the uncut corner from the intermediate shape after large rough machining with a large diameter tool, and create a medium rough machining area corresponding to only the uncut corner. It is possible to eliminate wasteful middle roughing time.

Further, according to the method of the above embodiment, the maximum value of the moving distances obtained along the tool trajectory closest to the product shape is expected with respect to the tool height of each layer of the contour processing of the medium roughing. Since the distance AD is assumed, the expected distance AD can be set to a constant value, and the search processing of the uncut corner can be performed easily and in a short time.Moreover, by adopting the maximum value, the range of the uncut corner can be reduced. It can be kept to the minimum necessary.

Further, according to the method of the above-described embodiment, the tool height of each layer of the contour line machining of the medium rough machining is compared with the machining range of the uncut corner machining area obtained by accurately searching as described above. The area surrounded by the tool path at the position where the ball end mill BM, which is the tool for rough machining, contacts the product shape, and the tool path at the position where the ball end mill BM contacts the uncut portion is obtained. Is used as the uncut corner area, so the narrow processing area that is not the uncut corner can be accurately deleted from the uncut corner processing area. The NC data can be generated so that only the uncut corner processing area is subjected to the medium roughing.
It is possible to reduce the number of steps for creating the C data and to eliminate useless time for rough machining.

Further, according to the method of the above embodiment, the minimum value of the moving distances obtained along the tool trajectory closest to the product shape can be obtained for the tool height of each layer of the contour processing of the medium roughing. The slope of the product shape with the specified inclination angle is set as the representative slope, and the representative slope is left uncut as the product shape to determine the corner machining area NM.Therefore, the tool path at the position where the ball end mill BM contacts the product shape is The product shape is the representative slope with the steepest inclination angle that can be obtained easily and in a short time from the product shape at the tool height of each layer in rough machining by the offset processing of a fixed distance and the minimum value is obtained. By determining the tool contact position, the possibility of the bite of the tool into the product shape can be reliably eliminated.

Although the present invention has been described above with reference to the illustrated examples, the present invention is not limited to the above-described example. For example, the method of the present invention has the following point. It is also applicable to the case where the radius is smaller than the radius of the tip of. The geometric calculation is performed in the same manner as described above, and the uncut corner processing region can be obtained. The method of the present invention can be similarly applied to a case where a tool having a rounded tip is used other than a ball end mill as a tool in the next step.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure of an embodiment of a method for creating a left-behind corner processing region according to an embodiment of the present invention using an embodiment of a method for searching for a remaining corner processing region for contour line processing according to the present invention;

FIG. 2 is a flowchart showing a method for creating a rough machining tool trajectory using the method for creating an uncut corner machining area in the embodiment.

FIG. 3 is an explanatory diagram showing large rough machining in a CAM system using NC data created by the method for creating a tool trajectory for rough machining.

FIG. 4 is an explanatory diagram showing medium roughing in a CAM system using NC data created by the method for creating a tool path for roughing.

FIG. 5 is an explanatory view showing a cross-sectional shape after a large rough machining by a large-diameter tool having a rounded tip.

FIG. 6 is an explanatory view showing a difference in a cross-sectional shape after a rough machining due to a difference in an inclination angle of a product shape.

FIG. 7 is an explanatory view showing a contact position of a medium roughing tool when a product shape has a gentle inclination angle.

FIG. 8 is an explanatory view showing a contact position of a middle roughing tool when a product shape has a steep inclination angle.

FIG. 9 is an explanatory diagram showing estimated distances obtained by the method of creating a remaining corner portion machining area according to the embodiment.

FIG. 10 is an explanatory diagram showing a method of obtaining a contact position of a tool for rough machining on a product shape in the method of forming a remaining machining corner area in the embodiment.

FIG. 11 is an explanatory diagram showing a plan view of a method of obtaining an uncut corner processing region in the method of forming an uncut corner processing region in the embodiment.

FIG. 12 is an explanatory diagram showing, in a cross-sectional view, how to obtain an uncut corner processing area in the method of forming an uncut corner processing area in the embodiment.

FIG. 13 is an explanatory diagram showing, in a plan view, a method of obtaining a tool path at a tool position where a medium-rough machining tool comes into contact with an uncut portion of large rough machining in the method of creating an uncut corner portion machining region in the embodiment. is there.

FIG. 14 is an explanatory view showing a method of obtaining a tool path at a tool position at which a middle roughing tool contacts a remaining part of large roughing in the method of creating a remaining part to be machined in the above-described embodiment; is there.

[Explanation of symbols]

 AD Expected distance AM Correction amount BM Ball end mill CC Round piece insert FF Product shape FM Face mill IF Intermediate shape after rough machining MF Shape after rough machining NM Uncut corner area RN Uncut corner area TP Tool path

Claims (4)

[Claims] An uncut corner in a contour machining in a previous process is formed by using a tool having a rounded radius of a tip portion different from that of the tool in the preceding process in order to create a tool path in a next process in which contour machining is performed. When searching for the machining range of the corner, the cross-sectional shape of the uncut portion in the previous process is the cross-sectional shape of the tool in the previous process located on the tool path closest to the product shape in each layer of the contour processing in the previous process. Based on the cross-sectional shape of the rounded tip portion, expressed by a combination of arcs or a combination of arcs and straight lines, the tool height of each layer of the next step contour processing corresponding to each layer of the previous step contour processing The position of the cross-sectional shape of the rounded tip of the tool in the next process, which is in contact with the cross-sectional shape of the uncut portion in the previous process represented by the combination of the arcs or the combination of the arc and the straight line, is determined. , The position is a contact position of the tool of the next process with respect to the uncut portion, from the contact position of the tool of the next process with respect to the uncut portion, from the position where the tool of the next process contacts the product shape. The moving distance is obtained, and the moving distance is set as the estimated distance.The contact position of the tool in the next process with respect to the uncut portion is offset toward the product shape by the estimated distance, and the tool in the next process is the product shape. A range in which an area surrounded by a tool path based on a position contacting the tool and a tool path based on the offset tool position is obtained, and the area is left uncut and set as a corner processing area. , Method for searching the remaining corner processing area for contour line processing. 2. The tool height of each layer of the contour processing in the next step, wherein a maximum value of the moving distances obtained along a tool path closest to the product shape is set as the expected distance. The method for searching for a remaining machining area for a contour line machining according to claim 1. 3. A tool trajectory based on a position where the tool of the next process contacts the product shape with respect to the tool height of each layer of the contour processing in the next process,
3. The method according to claim 1, wherein an area surrounded by a tool path based on a position at which the tool in the next step contacts the uncut portion is obtained, and the area is set as an uncut corner processing area. A method for creating an uncut corner processing area using the above described contour line processing uncut corner processing area search method. 4. The product shape of the inclination angle at which the minimum value of the moving distances obtained along the tool path closest to the product shape is obtained for the tool height of each layer of the contour processing in the next step. 4. The method according to claim 3, wherein the slope is a representative slope, and the representative slope is the product shape, and the uncut corner processing area is obtained.