CN116157220A

CN116157220A - Numerical control device and numerical control method

Info

Publication number: CN116157220A
Application number: CN202080104926.9A
Authority: CN
Inventors: 末田崇; 东俊博
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2020-07-29
Filing date: 2020-07-29
Publication date: 2023-05-23
Also published as: DE112020007477T5; JPWO2022024251A1; WO2022024251A1

Abstract

A numerical control device (1) is provided with an information acquisition unit (371) and a command generation unit (372). An information acquisition unit (371) acquires workpiece shape information indicating the shape of a workpiece that rotates about a rotation axis and has a cylindrical surface, and target site shape information indicating the shape of a target site in the cylindrical surface from which a chamfer or burr is removed. The instruction generation unit (372) generates, as an interpolation instruction used for chamfering or deburring of the target portion, an interpolation instruction corresponding to a shape obtained by expanding the target portion on a virtual plane formed by the rotation axis and an axis which is orthogonal to the rotation axis and which is virtually generated by rotation, based on the workpiece shape information and the target portion shape information acquired by the information acquisition unit (371).

Description

Numerical control device and numerical control method

Technical Field

The present invention relates to a numerical control device and a numerical control method for controlling an operation of a machine tool.

Background

A numerical control device that controls the operation of a machine tool, and causes the machine tool to machine a workpiece by operating a servo motor or the like included in the machine tool in accordance with instructions of a machining program. If the workpiece is machined, burrs or burrs may be generated in the machined portion. These burrs or burrs can be removed using a dedicated tool for chamfering or deburring, but the processing cost increases because a dedicated tool is required. In addition, it is sometimes difficult to perform uniform chamfering processing with a dedicated tool, and a time for replacing the dedicated tool is required, and the processing time increases.

Therefore, there has been proposed a technique for chamfering or deburring by a tool such as a ball nose end mill without using a special tool. For example, patent document 1 discloses a numerical control device capable of chamfering a boundary portion between an outer peripheral surface and a concave curved surface with respect to a cylindrical workpiece having a concave curved surface formed by a predetermined radius of curvature on its outer peripheral surface with respect to a central axis perpendicular to an axis of the workpiece as a center. The numerical control device generates tool path data for sequentially moving the ball nose end mill to predetermined movement positions in a 3-dimensional space defined by an X axis parallel to the axis of the workpiece, a Y axis perpendicular to the central axis, and an orthogonal 3 axis of a Z axis perpendicular to both the X axis and the Y axis.

Patent document 1: japanese patent laid-open No. 2005-271148

Disclosure of Invention

However, the technique described in patent document 1 can be used to calculate the tool position when there are 3 linear axes, i.e., the X axis, the Y axis, and the Z axis, and cannot be applied when there are no 3 linear axes, such as a 2-axis lathe.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a numerical control device capable of performing chamfering or deburring with high accuracy without using a dedicated tool for chamfering or deburring even in a machine tool such as a 2-axis lathe or the like in which no 3-axis is present on a linear axis.

In order to solve the above problems and achieve the object, a numerical control device of the present invention includes an information acquisition unit and a command generation unit. The information acquisition unit acquires workpiece shape information indicating a shape of a workpiece having a cylindrical surface and rotating about a rotation axis, and target site shape information indicating a shape of a target site from which a chamfer or burr is removed in the cylindrical surface. The instruction generating unit generates, as an interpolation instruction used for chamfering or deburring of the target portion, an interpolation instruction corresponding to a shape obtained by expanding the target portion on a virtual plane formed by the rotation axis and an axis which is orthogonal to the rotation axis and virtually generated by rotation, based on the workpiece shape information and the target portion shape information acquired by the information acquiring unit.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, even if a working machine such as a 2-axis lathe or the like having no 3-axis linear axis is used, chamfering or deburring can be performed with high accuracy without using a dedicated tool for chamfering or deburring.

Drawings

Fig. 1 is a diagram showing a configuration example of a numerical control device according to embodiment 1.

Fig. 2 is a diagram for explaining a hole forming operation performed by the machine tool according to embodiment 1.

Fig. 3 is a diagram for explaining chamfering processing by a pilot bit having a larger radius than a hole according to embodiment 1.

Fig. 4 is a diagram for explaining a chamfer width formed by the chamfering process shown in fig. 3.

Fig. 5 is a diagram for explaining chamfering processing using the hole drill according to embodiment 1.

Fig. 6 is a diagram showing an example of a chamfer width formed by chamfering using the hole drill according to embodiment 1.

Fig. 7 is a view showing a shape of an edge of a hole formed in a cylindrical surface according to embodiment 1 in a virtual plane.

Fig. 8 is a diagram for explaining a method of calculating the shape of the chamfer path in the numerical control device according to embodiment 1.

Fig. 9 is a diagram showing an example of the case where the elliptical path according to embodiment 1 is replaced with 4 spiral interpolation commands.

Fig. 10 is a diagram showing a relationship between a reduction in the depth in the X-axis direction and an ellipse radius in chamfering performed by the ball nose end mill according to embodiment 1.

Fig. 11 is a diagram showing the shape of a burr removal path corresponding to a hole in an end surface of a workpiece according to embodiment 1.

Fig. 12 is a flowchart showing an example of the instruction generation process performed by the instruction generation unit of the numerical control device according to embodiment 1.

Fig. 13 is a diagram showing an example of the hardware configuration of the numerical control device according to embodiment 1.

Fig. 14 is a diagram showing a configuration example of the numerical control device according to embodiment 2.

Fig. 15 is a flowchart showing an example of the instruction generation process performed by the instruction generation unit of the numerical control device according to embodiment 2.

Detailed Description

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

Embodiment 1.

Fig. 1 is a diagram showing a configuration example of a numerical control device according to embodiment 1. The numerical control device 1 controls a plurality of drive shafts included in the work machine 10. The numerical control device 1 processes a workpiece, which is an object to be processed, using a tool by controlling a plurality of drive shafts included in the machine tool 10. The following description will be given with respect to the machine tool 10 being a 2-axis lathe, but the machine tool 10 is not limited to the 2-axis lathe, and may be any machine tool having a rotation axis for rotating a workpiece.

The machine tool 10 includes a drive unit 9 for driving a workpiece, a tool, and the like. The tool driven by the driving unit 9 is, for example, a drill, a ball nose end mill, or the like. The driving unit 9 includes, for example, a driving mechanism that drives the tool while rotating the workpiece about a rotation axis. The driving direction of the tool formed by the driving section 9 is, for example, 2 directions of the X-axis direction and the Z-axis direction. Hereinafter, the axial direction will be described as 2 directions of the X-axis direction and the Z-axis direction, but the axial direction is not limited to this example.

The driving unit 9 includes:

servo motors

901 and 902 for moving the respective tools in corresponding axial directions among the 2 axial directions defined in the numerical control device 1; and detectors 97 and 98 for detecting the position and speed of the corresponding one of the

servomotors

901 and 902. The driving unit 9 includes an X-axis servo control unit 91 and a Z-axis servo control unit 92, which control corresponding servo motors among the

servo motors

901 and 902, respectively, based on a command from the numerical control device 1.

The X-axis servo control unit 91 controls the servo motor 901, thereby controlling the operation of the tool in the X-axis direction. Specifically, the X-axis servo control unit 91 performs feedback control to the servo motor 901 based on the rotational position and rotational speed of the servo motor 901 detected by the detector 97, thereby controlling the operation of the tool in the X-axis direction.

The Z-axis servo control unit 92 controls the servo motor 902, thereby controlling the operation of the tool in the Z-axis direction. Specifically, the Z-axis servo control unit 92 performs feedback control to the servo motor 902 based on the rotational position and rotational speed of the servo motor 902 detected by the detector 98, thereby controlling the operation of the tool in the Z-axis direction.

Work machine 10 may have a configuration with greater than or equal to 2 tool holders. In this case, the driving unit 9 includes an X-axis servo control unit 91, a Z-axis servo control unit 92,

servomotors

901 and 902, and detectors 97 and 98 for each of the tool holders.

The driving unit 9 further includes: a spindle motor 903 for rotating a spindle for rotating a workpiece; and a detector 99 that detects the position and rotation speed of the spindle motor 903. The rotation speed detected by the detector 99 corresponds to the rotation speed of the spindle motor 903. When the workpiece is formed in a cylindrical shape or a cylindrical shape, the axis of the spindle is the same as the axis of the cylindrical shaft of the cylindrical surface in the workpiece. Hereinafter, a cylindrical axis of the cylindrical surface of the workpiece may be referred to as a rotation axis of the workpiece.

The driving unit 9 includes a spindle servo control unit 93 that controls the spindle motor 903 based on a command from the numerical control device 1. The spindle servo control unit 93 performs feedback control to the spindle motor 903 based on the rotational position and the rotational speed detected by the detector 99.

When the machine tool 10 simultaneously machines 2 workpieces, the drive unit 9 includes 2 sets of spindle motors 903, detectors 99, and a spindle servo control unit 93. In this case, work machine 10 has greater than or equal to 2 tool holders.

The numerical control device 1 includes a control operation unit 2, an input operation unit 3, and a display unit 4. The input operation unit 3 is a unit for inputting information to the control operation unit 2, and is an input operation panel, for example. The input operation unit 3 is constituted by an input means such as a keyboard, a button, or a mouse, for example, and is operated by a user. The user inputs information such as a command, a machining program, or parameters to the control operation unit 2 by operating the input operation unit 3. The display unit 4 is configured by a display means such as a liquid crystal display device, and displays information processed by the control operation unit 2 on a display screen.

The control arithmetic unit 2 controls the machine tool 10 using a machining program defined by a coordinate system of the machine tool 10. The control computing unit 2 includes a screen processing unit 31, an input control unit 32, a data setting unit 33, a storage unit 34, a control signal processing unit 35, a PLC (Programmable Logic Controller: programmable logic controller) 36, an analysis processing unit 37, an interpolation processing unit 38, an acceleration/deceleration processing unit 39, and an axis data output unit 40. The PLC 36 may be disposed outside the control arithmetic unit 2.

The storage unit 34 includes a parameter storage area 341, a machining program storage area 342, a display data storage area 343, a shared area 344, a workpiece shape information storage area 345, and a target portion shape information storage area 346.

Parameters and the like used for the processing of the control operation unit 2 are stored in the parameter storage area 341. For example, in the parameter storage area 341, control parameters, servo parameters, and tool data for operating the numerical control device 1 are stored. A machining program used for machining a workpiece is stored in the machining program storage area 342.

In the display data storage area 343, screen display data displayed by the display unit 4 is stored. The screen display data is data for displaying information on the display unit 4. In the shared area 344, data temporarily used in the control computation unit 2 is stored. The workpiece shape information storage area 345 and the target portion shape information storage area 346 will be described in detail later.

The screen processing unit 31 performs control to display the screen display data stored in the display data storage area 343 on the display unit 4. The input control unit 32 receives information input from the input operation unit 3. The data setting unit 33 stores the information received by the input control unit 32 in the storage unit 34. That is, input information, which is information input from the input operation unit 3, is written into the storage unit 34 via the input control unit 32 and the data setting unit 33.

The control signal processing unit 35 is connected to the PLC 36, and receives signal information such as a relay for operating the work machine 10 from the PLC 36. The control signal processing section 35 writes the received signal information to the shared area 344 of the storage section 34. These signal information are referred to by the interpolation processing unit 38 during the machining operation. If the analysis processing unit 37 outputs an assist command to the shared area 344, the control signal processing unit 35 reads the assist command from the shared area 344 and transmits the read assist command to the PLC 36. The auxiliary command is a command other than a command for operating the numerical control axis, that is, the drive axis. Examples of auxiliary instructions are M-code or T-code.

The PLC 36 stores a ladder diagram program describing the mechanical operation performed by the PLC 36. If the PLC 36 receives the T code or M code as the auxiliary command, the processing corresponding to the auxiliary command is executed on the work machine 10 according to the ladder program. After executing the processing corresponding to the auxiliary command, the PLC 36 sends a completion signal indicating that the machine control is completed to the control signal processing unit 35 in order to execute the next block of the machining program.

In the control computing unit 2, the control signal processing unit 35, the analysis processing unit 37, and the interpolation processing unit 38 are connected via the storage unit 34, and the control signal processing unit 35, the analysis processing unit 37, and the interpolation processing unit 38 write and read information via the storage unit 34. In the following description, when writing and reading information between the control signal processing unit 35, the analysis processing unit 37, and the interpolation processing unit 38 are described, contents via the storage unit 34 may be omitted.

The machining program is selected by, for example, the user operating the input operation unit 3 and inputting the machining program number. The machining program number is written in the shared area 344 through the input control unit 32 and the data setting unit 33.

For example, when a loop start button provided in the input operation unit 3 is triggered and a selected machining program number in the shared area 344 is received from the shared area 344, the analysis processing unit 37 reads a machining program of the selected machining program number from the machining program storage area 342, and performs analysis processing for each block of the read machining program. The program blocks of the machining program are, for example, lines of the machining program.

The analysis processing unit 37 analyzes, for example, G code, T code, S code, M code, and the like. The G code is a command related to shaft movement and the like, and the T code is a tool change command and the like. The S code is a spindle motor rotation speed command, and the M code is a mechanical action command.

When the M code or the T code is included in the program block after the analysis, the analysis processing unit 37 transmits the analysis result to the PLC 36 via the shared area 344 and the control signal processing unit 35. When the M code is included in the program block after the analysis, the analysis processing unit 37 transmits the M code to the PLC 36 via the control signal processing unit 35. In this case, the PLC 36 performs mechanical control corresponding to the M code. When the execution of the mechanical control corresponding to the M code is completed in the PLC 36, the result indicating the completion of the M code is written into the storage unit 34 via the control signal processing unit 35. The interpolation processing unit 38 refers to the execution result written in the storage unit 34.

When the G code for the work machine 10 is included in the program block after the analysis, the analysis processing unit 37 transmits the analysis result to the interpolation processing unit 38 via the shared area 344. Specifically, the analysis processing unit 37 generates data of the movement condition corresponding to the G code and sends the data to the interpolation processing unit 38. The movement condition data is data of a condition for feeding a tool in which the tool is moving at the machining position, and includes data of a speed at which the tool is moving, data of a position at which the tool is moving, and the like.

The tool feeding means that the tool is moved in at least one of the X-axis direction (+x-axis direction) and the Z-axis direction (+z-axis direction). The analysis processing unit 37 also sends the data of the spindle rotation speed specified by the S code to the interpolation processing unit 38. The spindle rotation speed is the rotation speed of the spindle per unit time. In the case where the object to be driven by the driving unit 9 is not a tool but a tool rest, and the tool is fed by the movement of the tool rest, the data of the movement condition includes data of the speed of moving the tool rest, data of the position of moving the tool rest, and the like.

The interpolation processing unit 38 receives the movement condition data and the spindle rotation speed data, which are the analysis results of the analysis processing unit 37, and performs interpolation processing for the movement condition. The acceleration/deceleration processing unit 39 performs acceleration/deceleration processing for smoothly varying the acceleration with respect to the result of the interpolation processing supplied from the interpolation processing unit 38. The acceleration/deceleration processing unit 39 sends a speed command, which is a processing result of the acceleration/deceleration processing, to the shaft data output unit 40.

The shaft data output unit 40 outputs a speed command to the driving unit 9. Specifically, the axis data output unit 40 outputs a speed command to the X axis, a speed command to the Z axis, and a rotational speed command to the main axis to the drive control unit 90 included in the drive unit 9. Further, the stepping command is outputted from the shaft data output unit 40 to the driving unit 9 for the spindle without performing acceleration/deceleration processing.

The X-axis speed command is output to the X-axis servo control unit 91 via the drive control unit 90, and the Z-axis speed command is output to the Z-axis servo control unit 92 via the drive control unit 90. Thereby, the

servo motors

901 and 902 rotate, and the tool feed is performed. The rotational speed command to the spindle is output to the spindle servo control unit 93 via the drive control unit 90. Thereby, the spindle motor 903 rotates, and the workpiece rotates by performing the rotation of the spindle.

The machine tool 10 can perform machining of cutting the outer periphery of a workpiece, machining of forming a hole in the workpiece, or the like as the machining of the workpiece based on the control performed by the control computing unit 2. For example, when the machining of the workpiece is machining of cutting the outer periphery of the workpiece, the machine tool 10 rotates the spindle at a high speed based on the control by the control arithmetic unit 2, feeds the tool in the XZ axis direction, and performs turning by bringing the tool into contact with the workpiece. In the case where the machining of the workpiece is machining of the workpiece hole, the machine tool 10 operates as described below based on the control performed by the control arithmetic unit 2.

Fig. 2 is a diagram for explaining a hole forming operation performed by the machine tool according to embodiment 1. In fig. 2, "C" indicates the rotation direction of the workpiece, "R" indicates the radius of the workpiece, and "R" indicates the radius of the drill. The radius of a workpiece having a cylindrical surface can also be referred to as the radius. In addition, the Y-axis shown in FIG. 2 is not present in the structure of work machine 10.

As shown in fig. 2, in the case of the boring operation, the machine tool 10 stops the spindle after rotating the spindle to a predetermined position, moves the tool such as a drill to the near side of the boring position, rotates the tool at a high speed, and then moves the tool in the Z-axis direction, thereby performing boring.

If a workpiece is drilled with a tool such as a drill, burrs are generated at the edges of the hole. Burrs generated at the edges of the hole can be removed by chamfering operation by cutting the corners of the edges of the hole. Fig. 3 is a diagram for explaining chamfering processing by a pilot bit having a larger radius than a hole according to embodiment 1. In fig. 3, "r'" indicates the radius of the pilot bit. The pilot bit radius r' shown in fig. 3 is greater than the bit radius r shown in fig. 2. In addition, the Y-axis shown in FIG. 3 is not present in the structure of work machine 10.

As shown in fig. 3, in order to remove burrs generated at the edges of the hole, the machine tool 10 replaces the tool with a pilot bit having a larger radius than the hole, moves the pilot bit to the near side of the chamfering position, rotates the pilot bit at a high speed, and then moves the pilot bit in the Z-axis direction with respect to the hole position, thereby cutting and chamfering the corners of the edges of the hole as chamfering positions.

However, in chamfering processing performed by a pilot bit having a larger radius than the hole, a pilot bit having a larger radius than the hole is required, and a time for performing replacement work for the pilot bit having a larger radius than the hole is additionally required. Further, when the pilot bit having a larger radius than the hole is moved to the bottom position of chamfering, there is a problem that the chamfer width is different in the Z-axis direction and the Y-axis direction, and becomes nonuniform.

Fig. 4 is a diagram for explaining a chamfer width formed by the chamfering process shown in fig. 3. In fig. 4, a chamfer region in the workpiece observed in the XZ axis plane and a chamfer region in the workpiece observed in the XY axis plane are shown in a black-colored state. The chamfering area is an area subjected to chamfering.

As shown in fig. 4, the upper surface of the chamfer region in the workpiece as viewed in the XZ axis plane is the same as the position of the upper surface of the workpiece, but the upper surface of the chamfer region in the workpiece as viewed in the XY axis plane is lower than the position of the upper surface of the workpiece. Therefore, the chamfer width W2 in the Y-axis direction is smaller than the chamfer width W1 in the Z-axis direction. As described above, when the pilot bit is moved to the bottom position of chamfering, the chamfer widths in the Z-axis direction and the Y-axis direction are different from each other, and the chamfer widths become nonuniform.

Therefore, in the numerical control device 1, a tool for boring or a tool such as a ball nose end mill for surface machining is used, and a dedicated tool for chamfering is not used, so that a command for controlling the machine tool 10 is generated to enable the machine tool 10 to perform chamfering.

Here, chamfering using a boring bit as a cutter for boring will be described. Fig. 5 is a diagram for explaining chamfering using a hole drill according to embodiment 1, and fig. 6 is a diagram showing an example of a chamfer width formed by chamfering using a hole drill according to embodiment 1. Fig. 5 and 6 show examples of chamfering by an opening drill used for forming a hole in a workpiece, the opening drill having the same radius as the radius r of the hole. Therefore, the drill bit replacement operation during chamfering after the hole forming operation is not required.

The numerical control device 1 controls the machine tool 10 by a machining program including a chamfering command for chamfering the edge of the hole at a circle of radius r centered on the position of the hole on the virtual plane, i.e., the Y' Z axis plane. The chamfering instruction is an instruction of G code, for example, an instruction of "G185X10C60D 5". "G185X10C60D5" is a command to chamfer a hole of radius 5[ mm ] at a position of X10[ mm ] and C60[ degrees ]. As described above, since the tool replacement for chamfering is not required, if a chamfering instruction is described after the end of the processing of the machining in the machining program, the machining and chamfering can be completed by one program. The Y ' axis is an imaginary axis orthogonal to the rotation axis and generated by the rotation of the workpiece, and the Y ' Z axis plane is an imaginary plane formed by the Y ' axis and the rotation axis. The "hole observed in the Y 'Z axis plane" shown in fig. 5 is a hole formed in the workpiece by projecting the hole on the Y' Z axis plane.

The work machine 10 performs chamfering operation at a position shifted in the negative direction by the chamfer width amount from the upper surface of the work in the X-coordinate. In the case where the machine tool 10 is a 2-axis lathe, the Y-axis is not present in the structure of the 2-axis lathe, but the 2-axis lathe is capable of rotating the workpiece. Accordingly, the numerical control device 1 controls the machine tool 10 to rotate the workpiece in the direction indicated by the arrow C about the cylindrical axis of the workpiece as shown in fig. 5, thereby enabling machining similar to the case of operating in the Y' axis direction.

However, since the shape of the edge of the hole in the cylindrical surface of the workpiece is formed in an elliptical shape in the cylindrical surface, when chamfering is performed with respect to a circle having a radius r of the cylindrical surface passing hole, the chamfer width shown in fig. 6 becomes nonuniform. Fig. 7 is a view showing a shape of an edge of a hole formed in a cylindrical surface according to embodiment 1 in a virtual plane.

As shown in fig. 7, the shape of the edge of the hole formed in the cylindrical surface of the workpiece is an ellipse having a long radius S and a short radius r. Therefore, when chamfering is performed with respect to a circle having a radius r passing through the hole in the cylindrical surface of the workpiece, a cutter such as a drill may not come into contact with the hole formed in the cylindrical surface of the workpiece during chamfering operation in the Y' axis direction, and the chamfer width may become uneven.

Accordingly, in the numerical control device 1, in order to cause the machine tool 10 to execute the chamfering operation capable of achieving uniform chamfering, an interpolation instruction corresponding to the shape of the target portion in the cylindrical coordinate system is generated as the interpolation instruction used in the chamfering operation of the target portion, based on the workpiece shape information indicating the shape of the workpiece and the target portion shape information indicating the shape on the plan view of the target portion, which is the portion to be subjected to chamfering, among the cylindrical surfaces of the workpiece.

As shown in fig. 1, the numerical control device 1 includes the workpiece shape information storage area 345 and the target portion shape information storage area 346 described above in order to generate interpolation instructions. The numerical control device 1 further includes an information acquisition unit 371 and a command generation unit 372 in the analysis processing unit 37 of the control calculation unit 2.

The information acquisition unit 371 acquires the workpiece shape information from the workpiece shape information storage area 345, acquires the target site shape information from the target site shape information storage area 346, and acquires the machining program information from the machining program storage area 342. When the machining program to be executed is a chamfering machining program, the instruction generating unit 372 generates an interpolation instruction corresponding to the shape of the target portion in the cylindrical coordinate system based on the workpiece shape information and the target portion shape information acquired by the information acquiring unit 371.

The instruction generating unit 372 will be described below after the workpiece shape information storage area 345 and the target portion shape information storage area 346 are described first.

In the workpiece shape information storage area 345, workpiece shape information indicating the shape of the workpiece is stored. The workpiece is a workpiece having a cylindrical surface, such as a cylindrical workpiece or a columnar workpiece. The workpiece shape information of the workpiece having the cylindrical surface includes information on the radius and information on the height of the workpiece. The radius of the workpiece is a linear distance from the cylindrical axis of the workpiece to the cylindrical surface of the workpiece, and is a radius of the cylindrical surface of the workpiece. The height is the length of the workpiece in the cylindrical axis direction. The workpiece shape information stored in the workpiece shape information storage area 345 is information set in the storage unit 34 from the input operation unit 3, but may be set in the storage unit 34 by a machining program.

In the target site shape information storage area 346, target site shape information indicating the shape in plan view of the target site is stored. The shape of the target portion in plan view is a shape of the target portion projected on the YZ axis plane. For example, when the target portion is an edge of a hole, the shape of the target portion in a plan view is a shape projected on a YZ axis plane of the edge of the hole in the YZ axis plane. The target site shape information in the case where the edge of the hole opened by the hole drill having the radius r is the target site includes information on the center position of the hole and information on the radius r of the hole.

The YZ axis plane is a plane including a Y axis and a Z axis, and the Y axis is an axis orthogonal to each of the X axis and the Z axis, and is the same as the axis of the Y' axis. The target site shape information stored in the target site shape information storage area 346 is information set in the storage unit 34 from the input operation unit 3, but may be set in the storage unit 34 by a machining program.

The instruction generating unit 372 includes a path calculating unit 501 and a path generating unit 502. The analysis processing unit 37 analyzes a machining program, which is a chamfering program, and generates an interpolation instruction when it is determined that a chamfering instruction exists in a block of the chamfering program. The chamfering process is a process for chamfering.

The path calculation unit 501 calculates the shape of an accurate chamfer path on the cylindrical surface of the workpiece based on the workpiece shape information and the target portion shape information acquired by the information acquisition unit 371. For example, in the case of chamfering a hole formed by the hole drill, the path calculation unit 501 calculates, as a chamfer path, an ellipse having a short radius in the Z-axis direction and a long radius in the Y '-axis direction in the Y' -Z-axis plane. The Y 'Z axis plane is an imaginary plane formed by an imaginary Y' axis and Z axis generated according to the rotation direction of the workpiece.

Specifically, the path calculation unit 501 calculates the long radius S from the hole radius R and the workpiece radius R, and calculates an ellipse shown in fig. 7, in which the short radius is "R" and the long radius is "S", as the shape of the chamfer path in the Y' Z axis plane. As described above, the route calculation unit 501 converts the shape of the target portion in the plan view into the shape of the cylindrical coordinate system, thereby calculating the shape of the chamfer route. The shape of the chamfer path is the shape of the chamfer location in the cylindrical coordinate system. That is, the shape of the chamfer path is a shape in which the target portion is spread on the Y' Z axis plane. When the target portion is projected as a circle having a radius r through the Y 'Z axis plane, the shape in which the target portion is expanded on the Y' Z axis plane is an ellipse having a short radius r and a long radius S. The shape of the target portion which is spread on the Y ' Z axis plane is a shape longer than the shape projected on the Y ' Z axis plane in the Y ' axis direction than in the Z axis direction.

Fig. 8 is a diagram for explaining a method of calculating the shape of the chamfer path in the numerical control device according to embodiment 1. In fig. 8, "X1" is the length in the X-axis direction from the position a of the cylindrical axis of the workpiece to the position b of the center of the opening in the cylindrical surface of the workpiece, and "X2" is the length in the Y-axis direction from the position a to the position c of the edge of the hole formed in the cylindrical surface, and is the linear distance between the positions a and e. "R" is the workpiece radius. "

"is an angle formed by a straight line connecting the position a and the position b and a straight line connecting the position a and the position c.

The length X1 is the same length as the workpiece radius R. In addition, the length X2 is according to X ² +Y ² ＝R ² The relation of (2) can be represented by the following formula (1).

X2＝√(R ² －r ² ) · · · (1)

The distance X3 in the X-axis direction between the position b and the position c is a straight-line distance between the position d and the position c, and is represented by the following formula (2). The distance X3 can be represented by the following formula (3) according to the above formula (1) and the following formula (2).

X3＝X1－X2＝R－X2· · · (2)

X3＝R－√ (R ² －r ² ) · · · (3)

The long radius S in the ellipse can be represented by the following formula (4). Further, since the triangle whose vertices have positions a, b, and e has a relationship of the following formula (5), the long radius S can be represented by the following formula (6) according to the following formulas (4) and (5).

S＝R×acos{√(1－r ² /R ² )} · · · (6)

As described above, the path calculation unit 501 calculates the long radius S, and thereby can calculate an ellipse having the long radius S and a short radius of the same length as the radius r of the hole at the position a of the center as the shape of the chamfer path on the cylindrical surface of the workpiece. Hereinafter, a short radius having the same length as the radius r of the hole may be referred to as a short radius r.

The path generation unit 502 generates an interpolation instruction based on the shape of the chamfer path calculated by the path calculation unit 501. When the shape of the chamfer path is an ellipse, the interpolation command generated by the path generating unit 502 is a command for elliptical motion, and is a G code.

Here, as an example of a method for generating an interpolation instruction, a case where a plurality of interpolation instructions are generated as instructions for elliptical motion will be described with reference to fig. 9. Fig. 9 is a diagram showing an example of the case where the elliptical path according to embodiment 1 is replaced with 4 spiral interpolation commands. In fig. 9, points P0, P1, P2, P3, P4 are positions a, g, c, f, h shown in fig. 7.

In the example shown in fig. 9, the path generating unit 502 generates 4 interpolation commands based on 4 line segments obtained by dividing the ellipse 4 equally as a command for the elliptical motion. The 1 st interpolation instruction is a spiral interpolation instruction having the point P1 as a start point and the point P2 as an end point. The 2 nd interpolation instruction is a spiral interpolation instruction having the point P2 as a start point and the point P3 as an end point. The 3 rd interpolation instruction is a spiral interpolation instruction having the point P3 as a start point and the point P4 as an end point. The 4 th interpolation instruction is a spiral interpolation instruction having the point P4 as a start point and the point P1 as an end point.

Each of the spiral interpolation commands is a command for spiral interpolation in which the distance from the point P0, which is the coordinate of the center of the arc, to one of the start point and the end point is the same as the length of the short radius r, and the distance from the point P0 to the other of the start point and the end point is the same as the length of the long radius S. For example, the 1 st spiral interpolation instruction is an instruction for spiral interpolation having a radius from the point P0 to the point P1 as the start point of the short radius r and a radius from the point P0 to the point P2 as the end point of the long radius S.

As described above, the path generating unit 502 generates 4 spiral interpolation commands based on 4 line segments obtained by dividing the ellipse, thereby generating a command for the elliptical motion. In addition to generating 4 spiral interpolation commands by dividing an ellipse by 4, the path generating unit 502 may generate 8 spiral interpolation commands based on 8 line segments obtained by dividing an ellipse by 8, for example. The path generating unit 502 may approximate an ellipse by a plurality of straight lines having a minute length, and may generate a plurality of straight line interpolation commands, which are interpolation commands for the plurality of straight lines, as a command for an elliptical motion, and may approximate an ellipse by a plurality of arcs, and may generate a plurality of arc interpolation commands, which are interpolation commands for the plurality of arcs, as a command for an elliptical motion. Further, how to generate the instruction for the elliptical motion may be selectable based on the parameters stored in the storage unit 34, or may be selectable by a machining program.

The analysis processing unit 37 generates data of the movement condition based on the instruction generated by the path generating unit 502 and sends the data to the interpolation processing unit 38, similarly to the case of other processing programs. The interpolation processing unit 38 performs interpolation processing on the movement condition generated by the analysis processing unit 37, and the acceleration/deceleration processing unit 39 performs acceleration/deceleration processing on the result of the interpolation processing. The acceleration/deceleration processing unit 39 transmits a speed command, which is a processing result of the acceleration/deceleration processing, to the shaft data output unit 40, and the shaft data output unit 40 outputs the speed command to the driving unit 9. Thus, in the work machine 10, an elliptical chamfering operation is performed, and uniform chamfering of the hole is performed.

In the above example, the route generation method in the case of chamfering has been described, but the numerical control device 1 can cause the machine tool 10 to perform uniform burr removal similarly to the case of chamfering. Specifically, the path calculation unit 501 of the instruction generation unit 372 calculates, as the shape of the burr-removed path, the shape of the path having the same ellipse as in the case of chamfering and the position in the X-axis direction shown in fig. 5 as the same path as in the upper surface of the workpiece, based on the target portion shape information indicating the shape of the burr-removed target portion and the workpiece shape information. The path generating unit 502 of the command generating unit 372 generates an interpolation command corresponding to the shape of the burr-removed path calculated by the path calculating unit 501, similarly to the case of the chamfered path. Further, target portion shape information indicating the shape of the target portion from which the burr is removed is stored in the target portion shape information storage area 346 shown in fig. 1, and is acquired by the information acquisition unit 371.

In the above example, the target portion is the edge of the hole formed by the drill, but the target portion is not limited to the edge of the drilled hole. The command generating unit 372 can generate interpolation commands for chamfering or deburring, for example, for shapes other than circles such as edges of the key grooves. Specifically, the path calculation unit 501 obtains the above-described "S" based on the target portion shape information and the workpiece shape information, which are the shapes of the target portions to be chamfered or deburred, and calculates the shape of the target portion as the shape of the path by expanding the shape of the target portion in the Y' axis direction by S/r times, whereby the shape of the path for chamfering or deburring can be calculated for the shape other than the circle.

In addition, in the case where the path calculation unit 501 opens a hole at a position offset from the rotation axis of the workpiece, the shape of the path for chamfering or deburring can be calculated by setting the shape expanded in the Y' axis direction by S/r times as the shape of the path, as in the case described above.

In the above example, the tip of the hole-forming tool has the tip angle, but the tip of the hole-forming tool is not limited to the tip having the tip angle, and may be an arc-shaped tip such as a ball end mill.

Fig. 10 is a diagram showing a relationship between a reduction in the depth in the X-axis direction and an ellipse radius in chamfering performed by the ball nose end mill according to embodiment 1. As shown in fig. 10, the path calculation unit 501 can calculate the shape of a path of a plurality of ellipses in which the position of the tool in the X-axis direction is slightly shifted and the radius of the ellipse is slightly reduced. Thus, the chamfer can be smoothly machined in the work machine 10.

In the example shown in fig. 10, the positions of 3 elliptical actions are shown. The position of the 2 nd elliptical motion is offset by Δx and the radius of the ellipse is offset by Δr with respect to the position of the 1 st elliptical motion. The position of the 3 rd elliptical motion is offset by Δx and the radius of the ellipse is offset by Δr with respect to the position of the 2 nd elliptical motion. The number of ellipses having different amounts and diameters for shifting the tool indicates how to generate a command for elliptical motion, and can be specified by parameters or a machining program.

In the above description, chamfering or burr removal with respect to the cylindrical surface of the workpiece has been described, but the command generating unit 372 can generate an interpolation command corresponding to the burr removal for the hole formed in the end surface of the cylinder. Fig. 11 is a diagram showing the shape of a burr removal path corresponding to a hole in an end surface of a workpiece according to embodiment 1. In fig. 11, a hole having a radius r2 is formed in the end surface of the workpiece, and the shape of the burr-removed path for the hole in the end surface of the workpiece is shown as the shape of the burr-removed path generated by the path calculation unit 501.

The path calculation unit 501 of the instruction generation unit 372 calculates the length of a straight line by the Y 'Z axis plane based on the shape information of the target portion indicating the shape of the target portion for deburring and the workpiece shape information indicating the shape of the workpiece, and generates a straight line by the Y' Z axis plane as the shape of the path as shown in fig. 11. The burr removal path shown in fig. 11 is a path obtained by fixing the position of the tool in the X-axis direction and rotating the workpiece. The path calculation unit 501 of the instruction generation unit 372 generates a straight line interpolation instruction as an interpolation instruction corresponding to the generated burr-removed path.

Next, an example of the instruction generation process performed by the instruction generation unit 372 of the numerical control device 1 will be described with reference to a flowchart. Fig. 12 is a flowchart showing an example of the instruction generation process performed by the instruction generation unit of the numerical control device according to embodiment 1. The instruction generation process shown in fig. 12 is a process of deburring or chamfering the edge of the hole.

As shown in fig. 12, the instruction generation unit 372 of the numerical control device 1 analyzes a block to be analyzed among the machining programs to be executed (step S10). The instruction generating unit 372 determines whether or not a chamfer instruction or a burr removal instruction is present in the analysis target block (step S11).

When it is determined that the chamfering instruction or the burr removal instruction is present (Yes in step S11), the instruction generating unit 372 acquires the workpiece shape information and the target portion shape information (step S12). The target portion shape information obtained by the processing of step S12 is information indicating the shape of the portion to be subjected to chamfering or deburring. The command generating unit 372 calculates the major radius S of the ellipse based on the workpiece shape information and the target portion shape information acquired in step S12 (step S13).

The command generating unit 372 generates an interpolation command for the elliptical motion based on the long radius S calculated in step S13 and the radius r of the hole and the position a of the center of the hole included in the target portion shape information acquired in step S12 (step S14). The interpolation command for the elliptical motion includes, for example, an interpolation command for each of n segments, which is obtained by dividing the shape of the elliptical path into or approximating the path by the n segments. n is, for example, greater than or equal to 4. Each line segment is a spiral, an arc, or a straight line, and the interpolation command corresponding to each line segment is a spiral interpolation command, an arc interpolation command, or a straight line interpolation command. The spiral interpolation instruction is also called a circular interpolation instruction having a short radius and a long radius different from each other.

Next, the instruction generating unit 372 determines whether or not there is an unresolved block in the execution target machining program (step S15). When it is determined that there is an unresolved block (Yes in step S15), the instruction generating unit 372 jumps to step S10.

When it is determined that the chamfering instruction or the burr removal instruction is not present (step S11: no), or when it is determined that the unresolved block is not present (step S15: no), the instruction generating unit 372 ends the processing shown in fig. 12.

Fig. 13 is a diagram showing an example of the hardware configuration of the numerical control device according to embodiment 1. As shown in fig. 13, the numerical control apparatus 1 includes a computer having a processor 101, a memory 102, and an interface circuit 103.

The processor 101, the memory 102, and the interface circuit 103 can transmit and receive information to and from each other through, for example, the bus 104. The storage unit 34 is realized by a memory 102. The screen processing unit 31, the input control unit 32, and the axis data output unit 40 are realized by an interface circuit 103. The processor 101 reads and executes a program stored in the memory 102, thereby executing functions of the data setting unit 33, the control signal processing unit 35, the PLC 36, the analysis processing unit 37, the interpolation processing unit 38, the acceleration/deceleration processing unit 39, and the like. The processor 101 is, for example, an example of processing circuitry, including greater than or equal to one of CPU (Central Processing Unit), DSP (Digital Signal Processor) and system LSI (Large Scale Integration).

The memory 102 includes one or more of RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory). In addition, the memory 102 contains a recording medium in which a computer-readable program is recorded. The recording medium includes one or more of nonvolatile or volatile semiconductor memory, magnetic disk, flexible memory, optical disk, compact disk, and DVD (Digital Versatile Disc). The numerical control device 1 may include integrated circuits such as ASIC (Application Specific Integrated Circuit) and FPGA (Field Programmable Gate Array).

As described above, the numerical control device 1 according to embodiment 1 includes the information acquisition unit 371 and the command generation unit 372. The information acquisition unit 371 has workpiece shape information indicating a shape of a workpiece having a cylindrical surface that rotates about a rotation axis, and target portion shape information indicating a shape of a target portion of the cylindrical surface of the workpiece from which a chamfer or burr is removed. The command generating unit 372 generates, as an interpolation command used for chamfering or deburring of the target portion, an interpolation command corresponding to a shape obtained by expanding the target portion on a Y' Z axis plane which is a virtual plane formed by the rotation axis and an axis which is orthogonal to the rotation axis and virtually generated by rotation, based on the workpiece shape information and the target portion shape information acquired by the information acquiring unit 371. Thus, even if the numerical control device 1 is a machine tool such as a 2-axis lathe having no 3-axis linear axis, chamfering or deburring can be performed with high accuracy without using a dedicated tool for chamfering or deburring.

The target portion shape information includes a shape obtained by projecting the target portion on the Y' Z axis plane as information indicating the shape of the target portion. The command generating unit 372 converts the shape of the target portion into a shape developed on the Y 'Z axis plane which is the coordinate system of the cylindrical surface, and generates an interpolation command based on the shape developed on the converted Y' Z axis plane. Thus, the numerical control device 1 can generate an interpolation command used for chamfering or deburring the target portion, for example, according to the size of the target portion in the plan view.

The command generating unit 372 replaces the shape developed on the Y' Z axis with a plurality of line segments, and generates at least 1 type of interpolation commands among a straight line, an arc, and a spiral as interpolation commands corresponding to the plurality of line segments. This makes it possible to perform chamfering or deburring of the target portion with higher accuracy.

Embodiment 2.

The numerical control device according to embodiment 2 is different from the numerical control device 1 according to embodiment 1 in that the shape of the path is automatically replaced with a plurality of line segments based on the allowable error information, an interpolation instruction corresponding to the plurality of line segments is generated, the shape of the path is replaced with a plurality of line segments by a replacement method specified by a parameter or a machining program, and the interpolation instruction corresponding to the plurality of line segments is generated. The following description will be given mainly on the differences from the numerical control device 1 of embodiment 1, with the same reference numerals being given to the constituent elements having the same functions as those of embodiment 1, and the description will be omitted.

Fig. 14 is a diagram showing a configuration example of the numerical control device according to embodiment 2. As shown in fig. 14, the numerical control device 1A according to embodiment 2 is different from the numerical control device 1 in that a storage unit 34A and an analysis processing unit 37A are provided instead of the storage unit 34 and the analysis processing unit 37.

The storage unit 34A is different from the storage unit 34 in that it further includes an allowable error information storage area 347. The allowable error information is stored in the allowable error information storage area 347, and the allowable error information is an allowable range indicating errors of the path calculated by the analysis processing unit 37A and the tool path related to each interpolation instruction.

The analysis processing unit 37A includes an information acquisition unit 371A and a command generation unit 372A instead of the information acquisition unit 371 and the command generation unit 372. The information acquisition unit 371A acquires the allowable error information stored in the allowable error information storage area 347.

The instruction generating unit 372A is different from the instruction generating unit 372 in that a path generating unit 502A is provided instead of the path generating unit 502. The path generating unit 502A replaces the shape of the chamfer or burr removed path generated by the path calculating unit 501 with a plurality of line segments based on the allowable error information acquired by the information acquiring unit 371A, and generates an interpolation instruction corresponding to the plurality of line segments. Each line segment is a straight line, an arc or a spiral. The path generating unit 502A generates a straight line interpolation instruction, an arc interpolation instruction, or a spiral interpolation instruction as an interpolation instruction corresponding to each line segment.

For example, the route generation unit 502A divides the route shape, which is the shape of the route from which the chamfer or burr is removed, and replaces the route shape with a plurality of divided shapes. The path generating unit 502A determines a line segment closest to the division shape among the straight line, the circular arc, and the spiral, and generates an interpolation command corresponding to the tool path using the determined line segment as the tool path. The work machine 10 moves the tool through the tool path by the interpolation command corresponding to the tool path.

For example, the path generating unit 502A generates a straight line interpolation command as the interpolation command when the line segment closest to the division shape is a straight line, and generates an arc interpolation command as the interpolation command when the line segment closest to the division shape is an arc. When the line segment closest to the division shape is a spiral, the path generating unit 502A generates a spiral interpolation instruction as the interpolation instruction.

The path generating section 502A determines whether or not the difference between the path shape and the tool path is within the allowable range indicated by the allowable error information. For example, when the difference between the start point of the divided shape and the start point of the tool path, the difference between the end point of the divided shape and the end point of the tool path, and the difference between the intermediate point of the divided shape and the intermediate point of the tool path are within the allowable range, the path generating unit 502A determines that the difference between the divided shape and the tool path is within the allowable range.

When the difference between the tool path and the path shape is out of the allowable range, the path generating unit 502A continuously increases the number of line segments, replaces the path shape with a plurality of line segments, and repeats the above-described processing until the difference between the path shape and the tool path is out of the allowable range. Thus, the route generation unit 502A can automatically replace the shape of the route calculated by the route calculation unit 501 with a plurality of line segments without requiring prior settings of parameters, machining programs, and the like. In addition, in the case where the allowable error is small or in the case where the path shape is complex, the path shape is finally approximated by a plurality of minute line segments.

Next, an example of the instruction generation process performed by the instruction generation unit 372A of the numerical control device 1A will be described with reference to a flowchart. Fig. 15 is a flowchart showing an example of the instruction generation process performed by the instruction generation unit of the numerical control device according to embodiment 2. The instruction generation process shown in fig. 15 is a process of deburring or chamfering the edge of the hole. The processing of steps S20 to S23 and S29 shown in fig. 15 is the processing of steps S10 to S13 and S15 shown in fig. 12, and therefore, the description thereof is omitted.

As shown in fig. 15, the command generating unit 372A replaces the shape of the path with a plurality of line segments, and determines each line segment as a tool path (step S24). Next, the command generating unit 372A determines an interpolation command corresponding to each tool path determined in step S24 (step S25). Then, the command generating unit 372A calculates an error in the path shape and the tool path (step S26).

Next, the instruction generating unit 372A determines whether or not the error calculated in step S26 is within the allowable range (step S27). When it is determined that the error is not within the allowable range (step S27: no), the command generating unit 372A increases the number of line segments by 1 (step S28), and proceeds to step S24. When the command generating unit 372A determines that the error is within the allowable range (Yes in step S27), the process proceeds to step S29.

The hardware configuration example of the numerical control device 1A according to embodiment 2 is the same as that of the numerical control device 1 shown in fig. 13. The processor 101 reads and executes a program stored in the memory 102, and thereby can execute functions of the data setting unit 33, the control signal processing unit 35, the PLC 36, the analysis processing unit 37A, the interpolation processing unit 38, the acceleration/deceleration processing unit 39, and the like.

As described above, the information acquisition unit 371A of the numerical control device 1A according to embodiment 2 acquires the allowable error information indicating the allowable range of the error between the path shape, which is the shape on the Y' Z axis plane, and the path of the tool according to the interpolation command corresponding to each of the plurality of line segments. The instruction generating unit 372A generates interpolation instructions corresponding to the plurality of line segments so that the error falls within the allowable range. Thus, even when the target portion to be chamfered or deburred is approximated by a line segment such as a straight line, an arc, or a spiral, the numerical control device 1A can bring the precision of the chamfering or deburring within the allowable range.

The configuration shown in the above embodiment is an example, and other known techniques may be combined, or the embodiments may be combined with each other, and a part of the configuration may be omitted or changed without departing from the scope of the present invention.

Description of the reference numerals

1. A 1A numerical control device, a 2 control operation part, a 3 input operation part, a 4 display part, a 9 drive part, a 10 working machine, a 31 picture processing part, a 32 input control part, a 33 data setting part, 34A storage part, a 35 control signal processing part, a 37, 37A analysis processing part, a 38 interpolation processing part, a 39 acceleration and deceleration processing part, a 40 axis data output part, a 90 drive control part, a 91X axis servo control part, a 92Z axis servo control part, a 93 spindle servo control part, 97, 98, 99 detector, 341 parameter storage area, 342 machining program storage area, 343 display data storage area, 344 sharing area, 345 work piece shape information storage area, 346 target site shape information storage area, 347 allowable error information storage area, 371A information acquisition unit, 372A instruction generation unit, 501 path calculation unit, 502A path generation unit, 901, 902 servo motor, 903 spindle motor.

Claims

1. A numerical control device, characterized by comprising:

an information acquisition unit that acquires workpiece shape information indicating a shape of a workpiece that rotates about a rotation axis and has a cylindrical surface, and target site shape information indicating a shape of a target site from which a chamfer or burr is removed in the cylindrical surface; and

and a command generating unit that generates, as an interpolation command used for chamfering or deburring of the target portion, an interpolation command corresponding to a shape obtained by expanding the target portion on a virtual plane formed by the rotation axis and an axis that is orthogonal to the rotation axis and virtually generated by the rotation, based on the workpiece shape information and the target portion shape information acquired by the information acquiring unit.

2. The numerical control device according to claim 1, wherein,

the target portion shape information includes a shape obtained by projecting the target portion on the virtual plane, as information indicating the shape of the target portion,

the instruction generating unit converts the shape of the target portion into a shape developed on the virtual plane, and generates the interpolation instruction based on the converted shape developed on the virtual plane.

3. The numerical control device according to claim 2, wherein,

the command generating unit replaces the shape developed on the virtual plane with a plurality of line segments, and generates at least 1 kind of interpolation commands among a straight line, an arc, and a spiral as interpolation commands corresponding to the line segments.

4. The numerical control device according to claim 3, wherein,

the information acquisition unit acquires tolerance information indicating a tolerance range of an error between a shape developed on the virtual plane and a path of the tool according to an interpolation command corresponding to each of the plurality of line segments,

the instruction generating unit generates interpolation instructions corresponding to the plurality of line segments so that the error falls within the allowable range.

5. A numerical control method, comprising:

step 1, obtaining workpiece shape information indicating a shape of a workpiece having a cylindrical surface and rotating about a rotation axis, and target site shape information indicating a shape of a target site from which a chamfer or burr is removed in the cylindrical surface; and

And a step 2 of generating, as an interpolation command used for chamfering or deburring the target portion, an interpolation command corresponding to a shape obtained by expanding the target portion on a virtual plane formed by the rotation axis and an axis which is orthogonal to the rotation axis and virtually generated by the rotation, based on the workpiece shape information and the target portion shape information obtained in the step 1.