WO2025027765A1 - Numerical value control device and numerical value control method - Google Patents

Abstract

A numerical value control device (1) comprises: a vibration end determination unit (4) that, on the basis of a movement direction vector (10) representing the movement direction of a tool before vibration is applied, a blade edge vector (11) representing the orientation of a blade edge of the tool, and a vibration direction vector (12) representing a vibration direction that is different from the movement direction vector (10), determines vibration end selection information (13) indicating whether a command position, which is the movement path of the tool before the vibration is applied, is at the upper end of the vibration or the lower end of the vibration so that a vibration region for vibration cutting serves as a tool-side space from the command position; and a vibration waveform generation unit (6) that generates a vibration waveform for carrying out the vibration cutting on the basis of the vibration end selection information (13).

Description

Numerical control device and numerical control method

This disclosure relates to a numerical control device, which is a control device for a machine tool, and a numerical control method.

In cutting processes, a vibration cutting function is known that breaks up chips into small pieces by vibrating the cutting tool and workpiece relative to the cutting direction. During processing using the vibration cutting function, cutting is performed by alternating between forward motion in the same direction as the cutting direction and backward motion in the opposite direction to the cutting direction. The relative movement speed, which is the relative movement speed between the cutting tool and workpiece during forward motion, is higher than the relative movement speed during non-vibration processing, which is normal processing that does not involve vibration cutting. Therefore, even when a backward motion is performed, it is possible to make the average relative movement speed, which is the sum of forward and backward motions, equivalent to the relative movement speed during non-vibration processing, which makes it possible to apply vibration cutting without changing the processing time, i.e., productivity.

As mentioned above, in vibration cutting, forward and backward movements are repeated at a high relative movement speed, which causes the machine tool to vibrate. Therefore, in Patent Document 1, in order to reduce the load on the machine tool, the oscillation amplitude required to shred the chips is calculated based on the cutting angle of the tool, the oscillation direction is determined according to the calculated oscillation amplitude, and the tool is vibrated in a direction different from the machining direction.

International Publication No. 2022/269751

However, the technology in Patent Document 1 has the problem that when the machine is vibrated in a direction different from the machining direction to reduce the load on the machine, gouging of the workpiece cannot be avoided when the workpiece has a downward tapered or curved shape. Gouging refers to cutting excessively into the workpiece relative to the desired shape. Gouging causes machining defects, which can lead to problems such as remachining and the need to discard the workpiece.

The present disclosure has been made in consideration of the above, and aims to provide a numerical control device that realizes vibration cutting that can reduce the load on the machine tool without causing machining defects regardless of the machining shape.

In order to solve the above-mentioned problems and achieve the object, the numerical control device of the present disclosure performs vibration cutting of a workpiece using a tool. The numerical control device includes a vibration end determination unit that determines vibration end selection information indicating whether the command position is the upper end or lower end of vibration based on a movement direction vector indicating the movement direction of the tool before vibration is applied, a cutting edge vector indicating the orientation of the cutting edge of the tool, and a vibration direction vector indicating a vibration direction that is different from the movement direction vector, so that the vibration region of vibration cutting is a space on the tool side from the command position, which is the movement path of the tool before vibration is applied, and a vibration waveform generation unit that generates a vibration waveform for performing vibration cutting based on the vibration end selection information.

The numerical control device disclosed herein has the effect of realizing vibration cutting that can reduce the load on the machine tool without causing machining defects regardless of the machining shape.

FIG. 1 is a block diagram showing a configuration of a numerical control device according to a first embodiment. FIG. 1 is a diagram showing a positional relationship between a cutting edge vector used in the numerical control device according to the first embodiment and a workpiece; FIG. 1 is a diagram showing an example of a cutting edge vector used in the numerical control device according to the first embodiment; FIG. 1 is an explanatory diagram of a method for deriving an inflection point used in a numerical control device according to a first embodiment; FIG. 10 is an explanatory diagram of another method for deriving an inflection point used in the numerical control device according to the first embodiment; FIG. 10 is an explanatory diagram of another method for deriving an inflection point used in the numerical control device according to the first embodiment; FIG. 1 is a time chart for explaining an operation of a vibration waveform generating unit of a numerical control device according to a first embodiment; FIG. 11 is another time chart for explaining the operation of the vibration waveform generating unit of the numerical control device according to the first embodiment. FIG. 4 is a diagram showing the relationship between the movement direction and the vibration direction in the numerical control device according to the first embodiment; FIG. 4 is a diagram showing the relationship between the movement direction and the vibration direction in the numerical control device according to the first embodiment; FIG. 11 is another time chart for explaining the operation of the vibration waveform generating unit of the numerical control device according to the first embodiment. FIG. 11 is another time chart for explaining the operation of the vibration waveform generating unit of the numerical control device according to the first embodiment. FIG. 13 is a diagram showing vibration amplitude when the upper end is selected in the numerical control device according to the first embodiment; FIG. 13 is a diagram showing vibration amplitude when the lower end is selected in the numerical control device according to the first embodiment; FIG. 11 is a time chart for explaining a calculation procedure of another vibration waveform in the numerical control device according to the first embodiment; FIG. 1 is a diagram for explaining an operation of a vibration end determination unit of the numerical control device according to the first embodiment; FIG. 11 is another diagram for explaining the operation of the vibration end determination unit of the numerical control device according to the first embodiment. FIG. 2 is a diagram showing a positional relationship between a tool and a workpiece in the numerical control device according to the first embodiment; FIG. 11 is a diagram showing another positional relationship between a tool and a workpiece in the numerical control device according to the first embodiment; FIG. 2 is a diagram showing a correspondence relationship between the X-axis movement direction, the Z-axis movement direction, the vibration direction, and the position of the vibration region in the numerical control device according to the first embodiment; FIG. 1 is a diagram for explaining an operation of a path division unit of a numerical control device according to a first embodiment; FIG. 11 is a block diagram showing a configuration of a numerical control device according to a second embodiment. FIG. 13 is a diagram for explaining a method for determining a vibration direction vector in the numerical control device according to the second embodiment; FIG. 11 is a block diagram showing a configuration of a numerical control device according to a third embodiment. FIG. 13 is a diagram for explaining a waveform switching region used in a switching notification unit of a numerical control device according to a third embodiment. FIG. 13 is another diagram for explaining a waveform switching region used in the switching notification unit of the numerical control device according to the third embodiment. FIG. 1 is a diagram showing an example of a hardware configuration of a numerical control device according to first to third embodiments;

The numerical control device and numerical control method according to the embodiment are described in detail below with reference to the drawings.

Embodiment 1.
1 is a block diagram showing the configuration of a numerical control device 1 according to embodiment 1. The numerical control device 1 has a program analysis unit 2, a path division unit 3, a vibration end determination unit 4, a motion command generation unit 5, a vibration waveform generation unit 6, and a motion command output unit 7.

The program analysis unit 2 analyzes the machining program and creates information necessary for the motion command generation unit 5 to generate motion commands. Information necessary to generate motion commands includes the coordinate values of the start and end points (start and end points) that define the relative movement path between the tool and workpiece, the interpolation method for the movement path connecting the start and end points (linear interpolation, circular interpolation, etc.), the feed rate during movement, the number of rotations of the spindle, and the rotation direction of the spindle. In addition, information specifying whether vibration cutting is effective or not, or information specifying the shape of the vibration waveform may be included. Examples of information specifying the shape of the vibration waveform include vibration frequency, vibration amplitude, number of vibrations per unit rotation, and vibration waveform shape. Note that it is not necessary to specify all of this information specifying the shape of the vibration waveform, and some of it may be omitted.

The program analysis unit 2 also calculates a movement direction vector 10. The movement direction vector 10 is a vector that represents the direction of the tool movement path before vibration is superimposed. More specifically, in one line (hereinafter referred to as one block) described in the machining program, the vector that connects the start point and end point of the movement block that describes the tool movement is the movement direction vector 10. The movement direction vector 10 may simply be a vector that goes from the start point to the end point of the movement block, or it may be a vector whose magnitude is normalized to 1 for comparison with other vectors. The machining program may be, for example, a character string in the EIA (Electronic Industries Alliance)/ISO (International Organization for Standardization) format, or it may be a program called an interactive program that includes information such as the shape of the workpiece, the machining shape, and the machining dimensions.

The motion command generation unit 5 generates the motion commands required to make the machine tool perform the desired motion, based on the information created by the program analysis unit 2. The motion commands include movement commands for the drive axis of the machine tool to realize a command position, which is the relative movement path between the workpiece and the tool, and rotation commands for the spindle. Note that the movement commands do not include the vibration components used in vibration cutting. The movement commands are commands for the movement path to realize the desired shape described in the machining program.

The motion command output unit 7 outputs the motion commands generated by the motion command generation unit 5 to the servo motor and spindle motor of the machine tool to be controlled. This allows the machine tool to realize the desired motion described in the machining program. Note that a servo amplifier that controls the servo motor and a spindle amplifier that controls the spindle motor may be interposed between the motion command output unit 7 and the machine tool, in which case the motion command output unit 7 outputs motion commands to these amplifiers.

The above are the general roles of the components of the numerical control device 1, regardless of whether vibration cutting is being performed or not. Next, the vibration end determination unit 4, the vibration waveform generation unit 6, and the path division unit 3 will be explained in order.

The vibration end determination unit 4 generates vibration end selection information 13 in the vibration waveform based on the movement direction vector 10, cutting edge vector 11, and vibration direction vector 12. The vibration end selection information 13 is information that indicates whether the command position, which is the movement path of the tool before vibration is applied, is the upper end (top dead center) or the lower end (bottom dead center) of the vibration. The definitions of the upper and lower ends of vibration will be described later. The vibration end determination unit 4 determines the vibration end selection information 13 so that the vibration area of vibration cutting is the space from the command position to the tool side.

The cutting edge vector 11 is a vector that indicates the direction in which the cutting edge of the tool faces. FIG. 2 is a diagram showing the positional relationship between the cutting edge vector 11 used in the numerical control device 1 according to the first embodiment and the workpiece W. FIG. 3 is a diagram showing an example of the cutting edge vector 11 used in the numerical control device 1 according to the first embodiment. FIG. 2 shows an example of the positional relationship between the tool T, the cutting edge vector 11, and the workpiece W. FIG. 3 shows an example in which the direction of the cutting edge vector 11 is expressed as eight vector directions V1 to V8. The vector directions V1 to V8 will be described in detail later. The cutting edge vector 11 can also be expressed as a continuous numerical angle or vector information. The cutting edge vector 11 may be set as part of the information of the tool T, or may be calculated and selected according to the angle of the drive shaft that holds the tool T.

The vibration direction vector 12 is a vector that indicates the spatial direction of the relative vibration motion between the workpiece W and the tool T caused by vibration cutting. It is easy to understand that the coordinate system that serves as the reference for the vector is based on the direction along the drive axis of the machine tool, but a coordinate system in any direction in space may be used. For ease of explanation, we consider an orthogonal machine coordinate system along the X-axis, Y-axis, and Z-axis, which are the three basic drive axes of the machine tool. In the explanation, the X-axis direction is the up-down direction and the Z-axis direction is the left-right direction.

The vibration direction vector 12 may be determined, for example, according to the contents of the machining program. Specifically, the vibration direction vector 12 may be determined by referring to the settings of parameters, etc. in the machining program, or may be determined by rotating it by a specific angle relative to the direction of movement. In the settings of parameters, etc. described above, the axis used for vibration in vibration cutting is specified in the machining program, and the vibration direction vector 12 is determined as the direction along that axis. In addition, the vibration direction vector 12 may be determined by referring to parameters, etc. according to the operation contents of the machining program, or the vibration direction vector 12 may be changed according to the acceleration or load conditions of the drive axis, etc.

Next, the vibration waveform generating unit 6 will be described. The vibration waveform generating unit 6 has a generating unit 16 and a superimposing unit 17. The generating unit 16 generates a waveform of the movement path and a vibration waveform based on the information created by the program analyzing unit 2 and the motion commands generated by the motion command generating unit 5.

The superimposing unit 17 superimposes the waveform of the movement path generated by the generating unit 16 and the vibration waveform based on the vibration end selection information 13 to generate a final vibration waveform for achieving machining by vibration cutting, and outputs it as an operation command to the operation command output unit 7. The method of generating the vibration waveform will be described in detail later.

If the movement path analyzed by the program analysis unit 2 includes an inflection point α, the path division unit 3 divides the movement path at the inflection point α and calculates a movement direction vector 10 for each divided path.

FIG. 4 is an explanatory diagram of a method for deriving the inflection point α used in the numerical control device 1 according to the first embodiment. The inflection point α will be explained with reference to FIG. 4. The inflection point α refers to a point at which the direction of movement of one or more axes included in a movement block is reversed during the operation of the movement block. Inflection point α does not occur in linear movement, but it can occur in movement along a curved path such as a circular arc. At the inflection point α, the direction of movement of the target axis is reversed, and a zero cross occurs where the speed of the axis passes through 0 and becomes a speed of the opposite sign, so the inflection point α can be detected.

　Figure 1 in Figure 4 shows the relative movement path G of tool T in the X-axis and Z-axis directions with respect to workpiece W. In this specification, figure n refers to the nth figure from the top. The horizontal axis in figures 2 and onwards in Figure 4 indicates time. The vertical axes in figures 2 and onwards in Figure 4 indicate, from top to bottom, the position of tool T in the Z-axis direction, the speed of tool T in the Z-axis direction, the position of tool T in the X-axis direction, and the speed of tool T in the X-axis direction. In the movement path G in Figure 4, there is an inflection point α where the speed on the X-axis crosses zero.

Also, in a curved movement path G, the inflection point α can be detected by comparing the tangent vector of the start point with the tangent vector of the end point. FIG. 5 is an explanatory diagram of another method of deriving the inflection point α used in the numerical control device 1 according to the first embodiment. FIG. 6 is an explanatory diagram of another method of deriving the inflection point α used in the numerical control device 1 according to the first embodiment. FIG. 5 shows a movement path G including the inflection point α, and FIG. 6 shows a movement path G not including the inflection point α. In this method, the components of the tangent vector Sv of the start point S in each axial direction are compared with the components of the tangent vector Ev of the end point E in each axial direction, and if the signs of the two match, it is determined that the axis does not include the inflection point α in this movement path G, and conversely, if the signs of the two do not match, it is determined that the axis includes the inflection point α in this movement path G.

In the case of FIG. 5, the sign of the X-axis component of the tangent vector Sv of the starting point S is positive and the sign of the Z-axis component is negative, and the sign of the X-axis component of the tangent vector Ev of the end point E is negative and the sign of the Z-axis component is negative. In the case of FIG. 5, the sign of the X-axis component of the tangent vector Sv of the starting point S and the sign of the X-axis component of the tangent vector Ev of the end point E are reversed, so it can be determined that the inflection point α is included. In the case of FIG. 6, the sign of the X-axis component of the tangent vector Sv of the starting point S is positive and the sign of the Z-axis component is positive, and the sign of the X-axis component of the tangent vector Ev of the end point E is positive and the sign of the Z-axis component is positive. In the case of FIG. 6, the sign of each axial component of the tangent vector Sv of the starting point S and the sign of each axial component of the tangent vector Ev of the end point E match, so it can be determined that the inflection point α is not included.

Next, we will explain how the vibration waveform is generated by the vibration waveform generating unit 6. As mentioned above, the factors that determine the shape of the vibration waveform are the vibration amplitude, vibration frequency, and vibration waveform shape.

The vibration amplitude represents the distance between the upper and lower ends of the vibration waveform. For example, the vibration amplitude itself may be specified by directly writing it as a string of characters in the machining program, or a certain ratio to the feed speed of tool T (called the feed amplitude ratio) may be specified by writing it in the machining program or setting it as a parameter, and the vibration amplitude may be determined according to the feed speed.

The vibration frequency indicates how many times the machine vibrates per unit time. For example, the vibration frequency itself may be specified by directly writing it as a string in the machining program, or it may be determined according to the number of rotations of the spindle or the feed speed of the tool T. The vibration frequency may also be determined according to the number of rotations of the spindle by specifying the number of vibrations during one rotation of the spindle, or conversely, the number of rotations of the spindle per vibration may be specified. These values may be specified directly as a string in the machining program, or may be selected from parameters according to the machining conditions.

The vibration waveform shape indicates the type of vibration waveform, such as a triangular wave, sine wave, cosine wave, or square wave. The vibration waveform shape may also be specified directly as a string in the machining program, or may be set as a parameter value. As long as the vibration amplitude, vibration frequency, and vibration waveform shape are determined, there are no particular restrictions on how they may be determined.

The specific calculation procedure for the vibration waveform will be explained below. First, the case of a triangular wave will be explained.

FIG. 7 is a time chart for explaining the operation of the vibration waveform generating unit 6 of the numerical control device 1 according to the first embodiment. FIG. 7 shows a movement path in which only the Z axis moves. FIG. 7 shows a movement path including two movement blocks B1 and B2. The horizontal axis of each diagram in FIG. 7 indicates time. The vertical axis of each diagram in FIG. 7 indicates, from top to bottom, the Z axis position for the forward and backward positions of the movement path, the difference between the forward and backward positions, the amplitude of the reference vibration waveform, the movement amount of the vibration waveform of only the vibration component, and the Z axis position of the final vibration waveform.

As shown in Figure 7, the generation unit 16 of the vibration waveform generation unit 6 generates two movement paths, a forward position and a backward position, using the movement commands and vibration amplitudes of each axis included in the movement blocks B1 and B2 to be calculated. The backward position is a path that is delayed from the forward position by a time corresponding to the vibration amplitude or by the number of spindle rotations corresponding to the vibration amplitude so that the specified vibration amplitude can be ensured. Here, the time axis is considered as an example, but the vibration waveform can also be obtained using a similar calculation method when the number of spindle rotations is considered as the reference axis.

Next, the generating unit 16 generates a reference vibration waveform using the vibration frequency and the vibration waveform shape, as shown in FIG. 7, No. 3. The amplitude of the reference vibration waveform is 1, and by multiplying this reference vibration waveform by the difference between the forward position and the backward position shown in FIG. 7, No. 2, a vibration waveform containing only vibration components is generated, as shown in FIG. 7, No. 4.

Next, the superimposition unit 17 superimposes a vibration waveform containing only vibration components, as shown in FIG. 7, 4, onto the movement path including forward and backward positions that do not contain vibration components, as shown in FIG. 7, 1, to generate a final vibration waveform, as shown in FIG. 7, 5.

FIG. 8 is another time chart for explaining the operation of the vibration waveform generating unit 6 of the numerical control device 1 according to the first embodiment. FIG. 8 shows a movement path along which the X-axis and Z-axis move. FIG. 8 shows a vibration path corresponding to two movement blocks including movement block B1 and movement block B2. The horizontal axis of each diagram in FIG. 8 indicates time. The vertical axes of each diagram in FIG. 8 indicate, from the top, the Z-axis position for the forward and backward positions of the movement path, the movement amount of the vibration waveform of only the vibration component, the Z-axis position of the final vibration waveform, the X-axis position for the forward and backward positions of the movement path, the movement amount of the vibration waveform of only the vibration component, and the X-axis position of the final vibration waveform.

As shown in Figure 8, even if the movement path includes multiple axes, the vibration waveform generating unit 6 can generate a vibration waveform by performing similar calculations for the multiple axes. In Figure 8, only the Z axis operates in movement block B1, and the Z axis and X axis operate in movement block B2.

The generating unit 16 first generates two movement paths for the Z axis, forward and backward positions, using the Z axis movement command and vibration amplitude included in the movement blocks B1 and B2 to be calculated, as shown in FIG. 8, 1. Next, as shown in FIG. 8, 2, the generating unit 16 multiplies the reference vibration waveform for the Z axis, generated using the vibration frequency and vibration waveform shape, by the difference between the forward and backward positions for the Z axis, to generate a Z axis vibration waveform containing only vibration components. Next, the superimposing unit 17 generates the final vibration waveform for the Z axis, as shown in FIG. 8, 3, by superimposing the Z axis vibration waveform containing only vibration components, as shown in FIG. 8, 2, on the Z axis movement path including the forward and backward positions not containing vibration components, as shown in FIG. 8, 1.

In the same manner, the generation unit 16 generates two movement paths for the X-axis, an advance position and a retreat position, using the X-axis movement command and vibration amplitude, as shown in FIG. 8, No. 4. Next, the generation unit 16 generates an X-axis vibration waveform containing only vibration components by multiplying the reference X-axis vibration waveform generated using the vibration frequency and vibration waveform shape by the difference between the advance position and the retreat position for the X-axis, as shown in FIG. 8, No. 5. Next, the superimposition unit 17 generates a final vibration waveform for the X-axis by superimposing the X-axis vibration waveform containing only vibration components on the X-axis movement path including the advance position and the retreat position that do not contain vibration components, as shown in FIG. 8, No. 6.

Here, in the first embodiment, the load on the machine tool is reduced by making the vibration direction different from the movement direction. The vibration direction can be changed with respect to the movement direction by changing the ratio of the vibration amplitude between multiple axes with respect to the ratio between multiple axes in the movement path. FIG. 9 is a diagram showing the relationship between the movement direction and the vibration direction in the numerical control device 1 according to the first embodiment. FIG. 10 is a diagram showing the relationship between the movement direction and the vibration direction in the numerical control device 1 according to the first embodiment. In FIGS. 9 and 10, the vertical axis indicates the X-axis position, and the horizontal axis indicates the Z-axis position. In FIG. 9, in the movement block B2, the ratio of the vibration amplitude in the X-axis direction to the vibration amplitude in the Z-axis direction is made to match the ratio of the X-axis component to the Z-axis component in the movement path, and the vibration direction and the movement direction are matched. In FIG. 10, in the movement block B2, the ratio of the vibration amplitude in the X-axis direction to the vibration amplitude in the Z-axis direction is made to match the ratio of the X-axis component to the Z-axis component in the movement path, and the vibration direction and the movement direction do not match. In FIG. 10, the vibration amplitude in the Z-axis direction is increased and the vibration amplitude in the X-axis direction is decreased, resulting in a Z-axis bias. Conversely, when the vibration amplitude in the Z-axis direction is decreased and the vibration amplitude in the X-axis direction is increased, this is called X-axis bias.

Changing the vibration direction relative to the movement direction can also be achieved by vibrating only one of the multiple axes included in the movement path. In that case, a vibration waveform is generated, for example, as shown in Figure 11 or Figure 12. In Figures 11 and 12, the Z-axis and X-axis are operating in movement block B2, but only the X-axis is vibrated. Figure 11 shows the case where the upper end is selected in the vibration of the X-axis, and Figure 12 shows the case where the lower end is selected in the vibration of the X-axis.

FIG. 11 is another time chart for explaining the operation of the vibration waveform generating unit 6 of the numerical control device 1 according to the first embodiment. In FIG. 11, as in FIG. 8, only the Z axis operates in the moving block B1, and the Z axis and X axis operate in the moving block B2. The horizontal axis of each diagram in FIG. 11 indicates time. The vertical axis of each diagram in FIG. 11 indicates, from the top, the Z axis position for the forward and backward positions of the moving path, the movement amount of the vibration waveform of only the vibration component in the moving block B1, the Z axis position of the final vibration waveform, the X axis position for the forward and backward positions of the moving path, the movement amount of the vibration waveform of only the vibration component in the moving block B2, and the X axis position of the final vibration waveform.

First, as shown in FIG. 11, the generation unit 16 uses the Z-axis movement command and vibration amplitude included in the movement block B1 to generate two movement paths for the Z-axis, a forward position and a backward position, in the movement block B1. Furthermore, for the movement block B2, the generation unit 16 generates a movement path for the forward position only in the Z-axis. Next, as shown in FIG. 11, the generation unit 16 uses the vibration frequency and vibration waveform shape to generate a Z-axis vibration waveform for the movement block B1 with only the vibration component in the same manner as described above, as shown in FIG. 11, 2. Next, the superimposition unit 17 generates the final vibration waveform for the Z-axis by superimposing the Z-axis vibration waveform with only the vibration component on the Z-axis movement paths for the movement blocks B1 and B2, which include the forward position and the backward position, as shown in FIG. 11, 3.

Similarly, the generation unit 16 uses the X-axis movement command and vibration amplitude to generate two movement paths for the X-axis in the movement block B2, a forward position and a backward position, as shown in FIG. 11, 4. In this case, the upper end is selected in the X-axis vibration, and the forward position coincides with the commanded position. The backward position is a trajectory offset in the direction of time delay from the commanded position. Next, the generation unit 16 uses the vibration frequency and vibration waveform shape to generate an X-axis vibration waveform for the movement block B2 with only the vibration component in the same manner as described above, as shown in FIG. 11, 5. Next, the superimposition unit 17 generates the final X-axis vibration waveform by superimposing the X-axis vibration waveform with only the vibration component on the X-axis movement path for the movement block B2 including the forward position and the backward position, as shown in FIG. 11, 6.

FIG. 12 is another time chart for explaining the operation of the vibration waveform generating unit 6 of the numerical control device 1 according to the first embodiment. The horizontal and vertical axes of each diagram in FIG. 12 are the same as those in FIG. 11. The operation of the generating unit 16 and the superimposing unit 17 relating to diagrams 1 to 3 in FIG. 12 is the same as that in FIG. 11. As shown in diagram 4 in FIG. 12, the generating unit 16 uses the X-axis movement command and vibration amplitude to generate two movement paths, a forward position and a backward position, for the X-axis in the moving block B2, as shown in diagram 4 in FIG. 12. In this case, the lower end is selected in the vibration of the X-axis, and the backward position coincides with the command position. The forward position is a trajectory offset in the direction of moving forward in time by the vibration amplitude from the command position. Next, as shown in diagram 5 in FIG. 12, the generating unit 16 uses the vibration frequency and vibration waveform shape to generate an X-axis vibration waveform of only the vibration component for the moving block B2 in the same manner as described above. Next, the superimposition unit 17 generates the final vibration waveform for the X-axis by superimposing the X-axis vibration waveform of only the vibration component on the X-axis movement path for movement block B2, which includes the forward position and the backward position, as shown in FIG. 12, No. 6.

FIG. 13 is a diagram showing vibration amplitude when the upper end is selected in the numerical control device 1 according to the first embodiment. FIG. 14 is a diagram showing vibration amplitude when the lower end is selected in the numerical control device 1 according to the first embodiment. FIG. 13 shows the vibration amplitude in the X-axis direction in the case of the vibration waveform shown in FIG. 11, i.e., when the upper end is selected in the vibration of the X-axis, with the horizontal axis showing the Z-axis position and the vertical axis showing the X-axis position. FIG. 14 shows the vibration amplitude in the X-axis direction in the case of the vibration waveform shown in FIG. 12, i.e., when the lower end is selected in the vibration of the X-axis, with the horizontal axis showing the Z-axis position and the vertical axis showing the X-axis position.

As shown in Figure 13, if the upper end of the vibration is selected, vibration occurs in the area where the axis moves back from the commanded position. In other words, the upper end of the vibration is vibrated so that it is on the commanded trajectory. As shown in Figure 14, if the lower end of the vibration is selected, vibration occurs in the area where the axis moves forward from the commanded trajectory. In other words, the lower end of the vibration is vibrated so that it is on the commanded trajectory.

Note that the calculation procedure for the vibration waveform may be a method other than the above. The calculation procedure for a different vibration waveform will be explained using the case of a cosine wave as an example. FIG. 15 is a time chart for explaining the calculation procedure for another vibration waveform in the numerical control device 1 according to the first embodiment. The horizontal axis of each diagram in FIG. 15 indicates time. Each diagram in FIG. 15 shows, from top to bottom, a positive (+) reference vibration waveform, a negative (-) reference vibration waveform, a position command, a vibration waveform when the lower end is selected, and a vibration waveform when the upper end is selected.

The vibration waveform generating unit 6 generates a reference vibration waveform based on the vibration frequency and the vibration end selection information 13 determined by the vibration end determining unit 4. At this time, whether to select a waveform that vibrates between 0 and 1 as shown in FIG. 15-1, or a waveform that vibrates between -1 and 0 as shown in FIG. 15-2, is synonymous with whether the command position is the lower end or the upper end.

After multiplying the reference vibration waveform by a vibration amplitude according to the vibration conditions, the superimposing unit 17 superimposes the reference vibration waveform multiplied by the vibration amplitude on the motion command of each axis in the same way as in the case of the triangular wave described above, to generate a vibration waveform. When the lower end is selected for a position command such as that shown in FIG. 15, No. 3, a vibration waveform such as that shown in FIG. 15, No. 4 is generated, and when the upper end is selected, a vibration waveform such as that shown in FIG. 15, No. 5 is generated.

Next, the vibration end selection method performed by the vibration end determination unit 4 will be described. In the first embodiment, in order to solve the problems of the prior art, when the tool T vibrates relative to the workpiece W in vibration cutting, the vibration area is placed on the tool T side of the movement path G, not on the workpiece W side. The vibration area is the area sandwiched between the forward position and the backward position of the command position. In other words, the vibration operation is always performed on the tool T side, not on the workpiece W side, with respect to the movement path of the tool T described in the machining program. To achieve this, the vibration end determination unit 4 determines the positional relationship between the tool T and the workpiece W based on the cutting edge vector 11 and the movement direction vector 10, and determines the positional relationship between the vibration area and the movement path G based on the vibration direction vector 12 and the movement direction vector 10.

In the following, in order to make the explanation easier to understand intuitively, we will explain using the XZ plane as seen from the Y axis + direction, but there are no limitations based on the viewpoint, and if the viewpoint or coordinate system changes, the explanation can be applied regardless of the viewpoint by reinterpreting it appropriately.

FIG. 16 is a diagram for explaining the operation of the vibration end determination unit 4 of the numerical control device 1 according to the first embodiment. FIG. 17 is another diagram for explaining the operation of the vibration end determination unit 4 of the numerical control device 1 according to the first embodiment. In FIGS. 16 and 17, the XZ plane is divided into two regions by the movement path G, and hereinafter, these two regions are referred to as the upper and lower sides, or the left and right sides, with the movement path G as the boundary. In FIG. 16, the workpiece W is generally located below the movement path G, and a tool T (not shown) is located above the movement path G. In FIG. 17, the workpiece W is generally located above the movement path G, and a tool T (not shown) is located below the movement path G.

FIG. 18 is a diagram showing the positional relationship between the tool T and the workpiece W in the numerical control device 1 according to the first embodiment. FIG. 19 is a diagram showing another positional relationship between the tool T and the workpiece W in the numerical control device 1 according to the first embodiment. FIG. 18 corresponds to the positional relationship between the movement path G and the workpiece W as shown in FIG. 16. FIG. 19 corresponds to the positional relationship between the movement path G and the workpiece W as shown in FIG. 17. In the case of FIG. 18, the tool T comes into contact with the workpiece W from the +X-axis direction to perform machining, which corresponds to a typical machining case. In the case of FIG. 19, the tool T comes into contact with the workpiece W from the -X-axis direction to perform machining, which corresponds to, for example, internal diameter machining or machining using the tool T on the lower tool rest.

The cutting edge vector 11 is used to grasp the positional relationship between the workpiece W and the tool T. For example, when the cutting edge vector 11 is in the vector direction V3, V4, or V8 shown in FIG. 3, the cutting edge of the tool T faces downward, so it can be determined that the workpiece W is located on the lower side and the tool T is located on the upper side. When the cutting edge vector 11 is in the vector direction V1, V2, or V6 shown in FIG. 3, the opposite is true, and the cutting edge of the tool T faces upward, so it can be determined that the workpiece W is located on the upper side and the tool T is located on the lower side. When the cutting edge vector 11 is in the vector direction V1, V4, or V5, it can be determined that the workpiece W is located on the right side and the tool T is located on the left side. When the cutting edge vector 11 is in the vector direction V2, V3, or V7, it can be determined that the workpiece W is located on the left side and the tool T is located on the right side.

In this way, it is possible to grasp the positional relationship between the workpiece W and the tool T using the cutting edge vector 11. Note that even if the cutting edge vector 11 is treated as an angle or vector value rather than a number, it is possible to grasp the positional relationship between the workpiece W and the tool T using a similar concept. Furthermore, even if the definition of the viewpoint or cutting edge vector number changes, the same concept can be applied by interpreting it appropriately according to the situation.

Next, the relationship between the vibration direction vector 12 and the movement direction vector 10 will be explained. As in the example shown in FIG. 9, when vibrating in a direction along the movement path, the ratio between the axes of the movement direction vector 10 and the ratio between the axes of the vibration direction vector 12 are the same. If the ratio between the axes of the vibration direction vector 12 is changed, the vibration direction will be a direction different from the movement path. In this case, it can be seen from the example in FIG. 10 that the vibration direction of the vibration direction vector 12 faces toward the axis with a larger ratio than the axis ratio of the movement direction vector 10. In the case of FIG. 10, the axis ratio of the movement direction vector 10 in the X-axis direction and the Z-axis direction is the same, but the vibration amplitude in the Z-axis direction is larger than the vibration amplitude in the X-axis direction, and the vibration direction vector 12 approaches the horizontal axis and becomes closer to the Z-axis.

As in Figure 11 or Figure 12, when the vibration direction is made different from the movement direction by vibrating only one axis among the multiple axes included in the movement path, the ratio in the Z-axis direction can be considered to be 0 and the ratio in the X-direction to be 100%, which means it is closer to the X-axis.

In this way, the vibration end determination unit 4 can determine whether the vibration direction is above or below the movement path, or to the right or left, by comparing the movement direction vector 10 with the vibration direction vector 12.

FIG. 20 is a diagram showing the correspondence between the X-axis movement direction, Z-axis movement direction, vibration direction, and vibration area position in the numerical control device 1 according to the first embodiment. FIG. 20 shows the correspondence when the upper end is selected as the vibration end in the initial state. The position of the vibration area indicates whether the vibration area is on the upper or lower side of the movement path. The vibration end determination unit 4 has a memory table in which the correspondence shown in FIG. 20 is set.

In FIG. 20, for example, if the X-axis movement direction determined from the movement direction vector 10 is +, the Z-axis movement direction is -, and the vibration direction determined from the vibration direction vector 12 is closer to the X-axis, it indicates that the vibration area is below the movement path. Also, if the X-axis movement direction determined from the movement direction vector 10 is +, the Z-axis movement direction is -, and the vibration direction determined from the vibration direction vector 12 is closer to the Z-axis, it indicates that the vibration area is above the movement path. Also, if the X-axis movement direction determined from the movement direction vector 10 is -, the Z-axis movement direction is +, and the vibration direction determined from the vibration direction vector 12 is closer to the X-axis, it indicates that the vibration area is above the movement path. Also, if the X-axis movement direction determined from the movement direction vector 10 is -, the Z-axis movement direction is +, and the vibration direction determined from the vibration direction vector 12 is closer to the Z-axis, it indicates that the vibration area is below the movement path.

The vibration end determination unit 4 uses the movement direction vector 10 and the vibration direction vector 12 and the correspondence in FIG. 20 to obtain a first judgment result that judges whether the vibration direction is above or below the movement path, or to the right or left. As described above, the vibration end determination unit 4 also uses the cutting edge vector 11 to obtain a second judgment result that judges the positional relationship between the workpiece W and the tool T, i.e., the up-down and left-right positional relationship between the workpiece W and the tool T. The vibration end determination unit 4 compares the first judgment result with the second judgment result to judge whether the vibration area is on the workpiece W side or the tool T side. By referring to the comparison result, if the first judgment result (upper, lower, right, or left) is judged to be the tool T side, the vibration end determination unit 4 selects the upper end that corresponds to the correspondence in FIG. 20 as the vibration end selection information 13. On the other hand, in the vibration end determination unit 4, by referring to the collation result, if the first judgment result (upper, lower, right, or left) is judged to be the workpiece W side, the lower end is selected as the vibration end selection information 13. In this way, the vibration end determination unit 4 can determine the appropriate vibration end selection information 13.

Next, the path division operation performed by the path division unit 3 will be described. When the movement path is a curve including an inflection point α, the movement path is divided into multiple parts by the path division unit 3. The program analysis unit 2 can calculate the position of the curved inflection point α by geometrically analyzing the shape of the movement path, so the path division unit 3 can divide the path at the calculated inflection point α. For example, if the curve shape can be expressed mathematically, it is sufficient to differentiate and find the slope, i.e. the point where the speed becomes 0. Even if it cannot be calculated mathematically, the movement path can be divided finely and the change in position is found successively, and it can be determined that the point where the change in position is reversed is the inflection point α, so the path can be divided at the calculated inflection point α.

However, this method requires a large amount of calculation, so when real-time performance is required, it is more effective to perform calculations with a smaller amount of calculation. Furthermore, the purpose of dividing the path is to calculate the movement direction vector 10, and as mentioned above, the movement direction vector 10 is used to divide a plane area into two and to grasp the positional relationship between the tool T and workpiece W in combination with the cutting edge vector 11, or to determine the vibration area in combination with the vibration direction vector 12. For this reason, it is not necessary to precisely calculate the inflection point α, and it is sufficient to roughly grasp each movement direction vector 10 on the path after division.

FIG. 21 is a diagram for explaining the operation of the path division unit 3 of the numerical control device 1 according to the first embodiment. For example, as shown in FIG. 21, the tangent vector Sv of the start point S of the movement path G before division is extended to become the first half movement direction vector G1 after division. The intersection of the movement path G and the movement direction vector G1 is the inflection point α, and the second half movement direction vector G2 after division is the vector going from the inflection point α to the end point E. In the case of a curved path, the direction along the movement path G, i.e., the tangent to the path, changes gradually, so in order to accurately grasp the movement direction vector 10, it is necessary to carry out sequential calculations or to mathematically express the curve and handle it. However, with this method, the movement direction vector 10 can be obtained with a small amount of calculations.

Once the movement direction vectors 10 for each divided path including the inflection point α are obtained, the vibration end selection information 13 for each divided path can be obtained by performing the same processing as described above for each divided path.

In this way, according to embodiment 1, vibration end selection information 13 is determined based on the movement direction vector 10, cutting edge vector 11, and vibration direction vector 12, indicating whether the command position should be the upper end or lower end of vibration so that the vibration area is the space on the tool T side from the command position, and a vibration waveform for performing vibration cutting is generated based on the vibration end selection information 13. This makes it possible to perform vibration cutting that avoids gouging regardless of the machining shape, and realizes vibration cutting that can reduce the load on the machine tool without causing machining defects.

Embodiment 2.
22 is a block diagram showing the configuration of a numerical control device 1a according to the second embodiment. In the second embodiment, the vibration end determination unit 4 of the first embodiment is replaced with a vibration direction determination unit 8. Other configurations in the second embodiment are the same as those in the first embodiment, and therefore repeated explanations will be omitted.

The vibration direction determination unit 8 determines a vibration direction vector 12 based on the movement direction vector 10, the cutting edge vector 11, and the vibration end selection information 13, and inputs the determined vibration direction vector 12 to the vibration waveform generation unit 6. The vibration direction determination unit 8 has a memory table in which the correspondence shown in FIG. 20 is set. The vibration waveform generation unit 6 generates a vibration waveform for achieving machining by vibration cutting by superimposing the waveform of the movement path and the vibration waveform based on the information created by the program analysis unit 2, the motion command generated by the motion command generation unit 5, and the vibration direction vector 12, and outputs the generated waveform to the motion command output unit 7 as a motion command.

In the second embodiment, the correspondence shown in FIG. 20 is also set. Therefore, in this case, the upper end is fixedly selected as the vibration end selection information 13. As in the first embodiment, the vibration direction determination unit 8 uses the cutting edge vector 11 and the movement direction vector 10 to determine the positional relationship between the workpiece W and the tool T, that is, the up-down, left-right positional relationship between the workpiece W and the tool T. The vibration direction determination unit 8 also assigns the movement direction vector 10 to the correspondence in FIG. 20, thereby selecting one of the four areas including the vibration direction in FIG. 20. The vibration direction determination unit 8 then determines whether to select the area closer to the X-axis or the Z-axis in the selected area, using the up-down, left-right positional relationship between the workpiece W and the tool T determined using the cutting edge vector 11, so that the vibration region is the area on the tool T side.

For example, if the X-axis movement direction determined from the movement direction vector 10 is negative and the Z-axis movement direction is negative, the vibration direction in the lower right area in FIG. 20 (closer to the X-axis: upper side, closer to the Z-axis: lower side) is selected. In the positional relationship between the workpiece W and the tool T determined using the cutting edge vector 11, if the tool T is on the upper side, the direction closer to the X-axis is selected, and if the tool T is on the lower side, the direction closer to the Z-axis is selected.

Once it has been determined whether the vibration direction is closer to the X-axis or the Z-axis, the vibration direction determination unit 8 then determines the vibration direction vector 12. As described above, making the vibration direction different from the movement direction can be achieved by vibrating only one of the multiple axes included in the movement path, or by changing the ratio of vibration amplitudes between the multiple axes relative to the ratio between the multiple axes in the movement path.

If you choose the former method, the position can be determined automatically once the X-axis or Z-axis position is determined.

When the latter method is selected, the vibration direction vector 12 is determined based on the movement direction vector 10, for example. FIG. 23 is a diagram for explaining a method of determining the vibration direction vector 12 in the numerical control device 1a according to the second embodiment. As shown in FIG. 23, the vibration direction vector 12a may be generated by rotating the machining direction, i.e., the movement direction vector 10, by a certain angle θ. For example, the rotation angle θ may be specified by directly writing it as a character string in the machining program or setting it as a parameter. In addition, various conversion calculations may be performed on the vibration direction vector 12a that was not selected to calculate vibration direction vectors 12b, 12c, and 12d whose vibration regions are regions on the same side as the tool T. The vibration direction vector 12b is obtained by converting the vibration direction vector 12a into a line symmetrical shape with respect to the movement direction vector 10. The vibration direction vector 12c is obtained by converting the vibration direction vector 12a into a line symmetrical shape with respect to a specific axis parallel to the X-axis. The vibration direction vector 12d is obtained by converting the vibration direction vector 12a into a line symmetrical shape with respect to a specific axis parallel to the Z-axis.

When the vibration direction vector 12 is received from the vibration direction determination unit 8, the vibration waveform generation unit 6 calculates the vibration amplitude of each axis based on the vibration amplitude and the vibration direction vector 12 determined based on the information created by the program analysis unit 2 and the motion command generated by the motion command generation unit 5, and generates a vibration waveform in the same manner as in the first embodiment described above.

The lower end may be set as the vibration end selection information 13. In this case, a storage table similar to that shown in FIG. 20 may be created and used to correspond to the lower end. In addition, in the second embodiment, the vibration direction determination unit 8 may determine the vibration direction vector 12 without using the vibration end selection information 13.

The idea of dividing the movement path including the inflection point α described in the first embodiment into multiple parts can also be applied to the second embodiment. The path division unit 3 calculates a corresponding movement direction vector 10 for each of the multiple divided movement paths. The vibration direction determination unit 8 determines a vibration direction vector 12 based on the above-mentioned determination method according to each movement direction vector 10.

In this way, according to the second embodiment, the vibration direction vector 12 is determined based on the movement direction vector 10, the cutting edge vector 11, and the vibration end selection information 13 so that the vibration area is the space on the tool T side from the command position, and a vibration waveform for performing vibration cutting is generated based on the vibration direction vector 12. This makes it possible to perform vibration cutting that avoids gouging regardless of the machining shape, and realizes vibration cutting that can reduce the load on the machine tool without causing machining defects.

Embodiment 3.
In the third embodiment, the focus is on the operation when switching the vibration waveform, and a waveform switching region is provided at the boundary between the moving paths. The following mainly describes the features of the third embodiment, and the description of the contents overlapping with the first and second embodiments will be omitted.

By using the methods described in the first and second embodiments, vibration cutting that avoids scraping can be achieved, but the vibration waveform may change for each movement path. Ideally, the vibration waveform would switch at the moment the movement path switches, but in reality, due to various factors, it may be difficult to accurately capture the moment the movement path switches, or the timing of the vibration waveform switching may be off, which may affect machining using vibration cutting.

Examples of factors include discretization errors resulting from digital processing in software, discrepancies or delays in communication timing between the numerical control device and the device that controls the motor (such as a servo amplifier), and overlapping of movement paths for purposes such as smoothing the speed between movement paths. In addition, in the case of a curved path that has an inflection point α, it may be difficult to precisely detect the inflection point α in terms of the amount of calculations or processing time required.

In the third embodiment, a waveform switching area Ta is provided at the boundary between the movement paths, and the vibration waveform is switched without affecting the processing by transitioning between the vibration waveforms in the waveform switching area Ta.

FIG. 24 is a block diagram showing the configuration of a numerical control device 1b according to the third embodiment. In the numerical control device 1b according to the third embodiment, a switching notification unit 9 is provided, the vibration end determination unit 4 according to the first embodiment and the vibration direction determination unit 8 according to the second embodiment are provided, and priority information 21 for switching between the vibration end selection information 13 and the vibration direction vector 12 is added.

First, the waveform switching region Ta will be described to explain the operation of the switching notification unit 9. The waveform switching region Ta is defined as an area within a threshold range for the position or speed of an axis included in the movement path.

FIG. 25 is a diagram for explaining the waveform switching region Ta used in the switching notification unit 9 of the numerical control device 1b according to the third embodiment. The first diagram in FIG. 25 shows the movement path of the XZ axis. The horizontal axis in the second diagram onward in FIG. 25 shows time. The vertical axis in the second diagram onward in FIG. 25 shows, from the top, the Z axis position of the movement path, the Z axis speed of the movement path, the X axis position of the movement path, and the X axis speed of the movement path.

FIG. 26 is another diagram for explaining the waveform switching region Ta used in the switching notification unit 9 of the numerical control device 1b according to the third embodiment. FIG. 1 in FIG. 26 shows the movement path of the XZ axis. The horizontal axis of FIG. 26 from FIG. 26 onwards shows time. The vertical axis of FIG. 26 from FIG. 26 onwards shows, from the top, the Z axis position of the movement path, the Z axis speed of the movement path, the X axis position of the movement path, and the X axis speed of the movement path.

In FIG. 25, a straight movement path is shown, and in FIG. 26, a curved movement path is shown. In the example shown in FIG. 25, thresholds including a lower threshold Th1 and an upper threshold Th2 are set for the X-axis position, and the waveform switching region Ta is the time from when the X-axis position enters between the lower threshold Th1 and the upper threshold Th2 to when it leaves the gap. In FIG. 25, by setting a lower threshold Th1 and an upper threshold Th2 that add a fixed value in both the negative and positive directions to the end point of the movement path, the region immediately before the end of the previous movement path and immediately after the start of the next movement path of the two movement paths is defined as the waveform switching region Ta.

In Figure 26, thresholds including a lower threshold Th1 and an upper threshold Th2 are set for the X-axis speed. When detecting the inflection point α in a curved movement path, for example, the zero crossing of one of the axes included in the movement path is detected. In Figure 26, by setting a lower threshold Th1 and an upper threshold Th2 that add a certain amount to the X-axis speed of 0 in both the negative and positive directions, the area before and after the inflection point α is defined as the waveform switching area Ta.

Setting the waveform switching area Ta based on position is suitable for detecting movement routes where the position changes significantly, as shown in Figure 25. However, in cases where there is a gradual change in position, as shown in Figure 25, unless an appropriate threshold is set, the waveform switching area Ta may become excessively large. On the other hand, when setting the waveform switching area Ta based on speed, it is relatively easy to adjust the width of the waveform switching area Ta, even for movement routes where there is a gradual change in position, as shown in Figure 26. Conversely, in cases where the speed of a movement route changes suddenly, as shown in Figure 25, it may be difficult to set a threshold value based on speed, so it is necessary to decide which information to set the threshold value for depending on the characteristics of the movement route. Note that in the case of Figure 25, it is also possible to detect by using acceleration as the judgment target.

The selection of data that serves as the criteria for thresholds, such as position and speed, or the value of the threshold may be specified by directly entering it as a character string in the machining program, or the selection may be made by referencing a parameter. As explained above, the selection may be made according to the path, such as by position for a straight path and by speed for the inflection point α of a curved path.

The position and speed data used to detect the waveform switching area Ta may be command values output from the numerical control device 1b to the amplifier and motor, or feedback values obtained by sending values obtained from a sensor such as an encoder provided on the motor to the numerical control device 1b. By using the feedback value, it is possible to move to the waveform switching operation after confirming that the motor has actually reached a position and speed corresponding to the threshold value.

In this way, when the switching notification unit 9 detects that the waveform switching region Ta has been entered using the motion command generated by the motion command generation unit 5, it notifies the vibration waveform generation unit 6 of a switching signal, which is a notification of reaching the waveform switching region Ta. The waveform switching operation performed by the vibration waveform generation unit 6 will be described below. The waveform switching operation may be any operation for switching between two different vibration waveforms, and any waveform switching operation may be performed.

One example of a waveform switching operation is the stopping of vibration. When the vibration waveform generating unit 6 receives a notification from the switching notification unit 9 that the waveform switching region Ta has been reached, it stops superimposing the vibration waveform on the operation command. In other words, the switching operation is achieved by switching the vibration waveform superimposed on the operation command to the next vibration waveform. By stopping the vibration near the boundary between the two vibration waveforms and not performing vibration cutting within the waveform switching region Ta, it is possible to eliminate the impact on machining caused by malfunctions in waveform switching.

Another example of a waveform switching operation is to gradually increase or decrease the amplitude. Ideally, the midpoint of the waveform switching region Ta should be the boundary of the movement path, but this can shift due to the various factors mentioned above. However, if the threshold is set appropriately, the midpoint should exist within the waveform switching region Ta, and it is highly likely that the midpoint will be near the center of the waveform switching region Ta. Therefore, for example, the amplitude can be gradually decreased with a slope such that the vibration is completely attenuated in the center of the waveform switching region Ta, and the amplitude can be gradually increased from the center with a slope such that the original amplitude is reached when the waveform switching region Ta is passed. Alternatively, it is possible to create an area where vibration stops near the center of the waveform switching region Ta by making the slope of the amplitude attenuation and increase even steeper.

Next, the selection of vibration in the vibration waveform generating unit 6 will be described. As described in embodiment 1, the vibration end determining unit 4 determines the vibration end in the vibration waveform based on the movement direction vector 10, the cutting edge vector 11, and the vibration direction vector 12 so that the vibration area is on the same side as the tool T, and generates vibration end selection information 13. As described in embodiment 2, the vibration direction determining unit 8 determines the vibration direction vector 12 based on the movement direction vector 10, the cutting edge vector 11, and the vibration end selection information 13 so that the vibration area is on the same side as the tool T.

The priority information 21 is information indicating whether to select a vibration end selection priority mode using the vibration end selection information 13 output from the vibration end determination unit 4, or a vibration direction vector priority mode using the vibration direction vector 12 output from the vibration direction determination unit 8. The vibration waveform generation unit 6 selects either the vibration end selection priority mode or the vibration direction vector priority mode based on the priority information 21, and operates according to the selected mode. There are no limitations on the method of specifying the priority information 21, and it may be specified as a character string in the machining program or by a parameter.

In order to achieve vibration cutting, the tool T must be vibrated relative to the workpiece W, and depending on the structure of the machine tool, the suitability for this vibration operation may differ between the drive axes. For this reason, there are cases where a specific axis is to be prioritized as the vibration axis, or conversely, cases where a specific axis is not to be used as the vibration axis. Specifically, the closer the axis is to the tip that holds the tool T, the lighter it tends to be, and therefore the less energy required for vibration is advantageous. On the other hand, in the case of an axis that supports many axes or machine structures, more energy is required for vibration, which can also lead to vibrating the entire machine, increasing the possibility of adverse effects from the vibration operation associated with vibration cutting. The priority information 21 is provided to achieve vibration operation that takes such external factors into account.

In this way, according to the third embodiment, a waveform switching area Ta is provided at the boundary between the movement paths to notify a switching signal when the axis position or speed reaches a threshold value, and when the switching signal is notified, a waveform switching operation is performed to generate a vibration waveform, thereby preventing chipping caused by switching of the vibration waveform.

Here, the hardware configuration of the numerical control devices 1, 1a, 1b will be described. FIG. 27 is a diagram showing an example of the hardware configuration of the numerical control devices 1, 1a, 1b according to the first to third embodiments. The numerical control devices 1, 1a, 1b can be realized by the processor 301, memory 302, and interface circuit 303 shown in FIG. 27. An example of the processor 301 is a CPU (also called a Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). An example of the memory 302 is a RAM (Random Access Memory) or a ROM (Read Only Memory).

The numerical control devices 1, 1a, and 1b are realized by the processor 301 reading and executing a program for executing the operations of the numerical control devices 1, 1a, and 1b, which is stored in the memory 302. This program can also be said to cause a computer to execute the procedures or methods of the numerical control devices 1, 1a, and 1b. The memory 302 is also used as a temporary memory when the processor 301 executes various processes. Note that the functions of the numerical control devices 1, 1a, and 1b may be realized partly by dedicated hardware and partly by software or firmware.

The configurations shown in the above embodiments are examples of the contents of this disclosure, and may be combined with other known technologies, or the embodiments may be combined with each other. In addition, parts of the configurations may be omitted or modified without departing from the gist of this disclosure.

1, 1a, 1b: Numerical control device, 2: Program analysis unit, 3: Path division unit, 4: Vibration end determination unit, 5: Motion command generation unit, 6: Vibration waveform generation unit, 7: Motion command output unit, 8: Vibration direction determination unit, 9: Switching notification unit, 10, G1, G2: Movement direction vector, 11: Cutting edge vector, 12, 12a, 12b, 12c, 12d: Vibration direction vector, 13: Vibration end selection information, 16: Generation unit, 17: Superimposition unit, 21: Priority information, 301: Processor, 302: Memory, 303: Interface circuit, G: Movement path, T: Tool, Ta: Waveform switching area, W: Workpiece.

Claims (8)

A numerical control device that performs vibration cutting of a workpiece using a tool,
a vibration end determination unit that determines vibration end selection information indicating whether the command position should be the upper end or lower end of vibration based on a movement direction vector indicating the movement direction of the tool before vibration is applied, a cutting edge vector indicating the orientation of the cutting edge of the tool, and a vibration direction vector indicating a vibration direction that is a direction different from the movement direction vector, so that the vibration region of vibration cutting is a space on the tool side from a command position, which is the movement path of the tool before vibration is applied; and
a vibration waveform generating unit that generates a vibration waveform for performing vibration cutting based on the vibration end selection information. A path dividing unit divides the moving path into a plurality of moving paths by inflection points,
The numerical control device according to claim 1 , wherein the vibration end determination unit determines the vibration end selection information corresponding to each of the plurality of divided movement paths based on the movement direction vector in each of the plurality of divided movement paths. A numerical control device that performs vibration cutting of a workpiece using a tool,
a vibration direction determination unit that determines a vibration direction vector indicating a vibration direction that is a direction different from the movement direction vector based on a movement direction vector indicating the movement direction of the tool before vibration is applied and a cutting edge vector indicating the orientation of the cutting edge of the tool, so that a vibration region of vibration cutting is a space on the tool side from a command position, which is the movement path of the tool before vibration is applied;
a vibration waveform generating unit that generates a vibration waveform for performing vibration cutting based on the vibration direction vector. A path dividing unit divides the moving path into a plurality of moving paths by inflection points,
The numerical control device according to claim 3 , wherein the vibration direction determination unit determines the vibration direction vector corresponding to each of the plurality of divided movement paths based on the movement direction vector in each of the plurality of divided movement paths. Further comprising a switching notification unit that notifies a switching signal of the vibration waveform,
The numerical control device according to claim 1 , wherein the vibration waveform generating unit generates the vibration waveform by executing a waveform switching operation based on the switching signal notified from the switching notifying unit. The numerical control device according to claim 5 , wherein the switching notification unit issues the switching signal when a position or a speed of an axis included in the movement path reaches a threshold value. 1. A numerically controlled method for performing vibration cutting of a workpiece using a tool, comprising:
a step of determining vibration end selection information indicating whether the command position is to be the upper end or lower end of vibration based on a movement direction vector indicating the movement direction of the tool before vibration is applied, a cutting edge vector indicating the orientation of the cutting edge of the tool, and a vibration direction vector indicating a vibration direction different from the movement direction vector, so that the vibration region of vibration cutting is a space on the tool side from a command position, which is the movement path of the tool before vibration is applied;
generating a vibration waveform for performing vibration cutting based on the vibration end selection information. 1. A numerically controlled method for performing vibration cutting of a workpiece using a tool, comprising:
determining a vibration direction vector indicating a vibration direction different from the movement direction vector based on a movement direction vector indicating the movement direction of the tool before vibration is applied and a cutting edge vector indicating the orientation of the cutting edge of the tool, so that a vibration region of vibration cutting is a space on the tool side from a command position, which is the movement path of the tool before vibration is applied;
generating a vibration waveform for performing vibration cutting based on the vibration direction vector.

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