Numerical control device, machine tool, and control method for machine tool

Abstract

The numerical control device includes: an extraction unit that extracts at least one non-cutting section in which a tool does not contact a workpiece in a tool path along which the tool moves, based on sensor information representing a physical quantity detected by a sensor; a setting unit that sets an end position of a reverse movement in which the tool moves backward along the tool path in one of the at least one non-cutting sections extracted by the extraction unit; and a control unit that controls the reverse movement.

Description

Technical Field

[0001] The present invention relates to a numerical control device, a machine tool, and a control method for a machine tool. Background Art

[0002] Conventionally, a machine tool having a reverse function that causes a tool to move backward along a machining path has been known (Patent Document 1). For example, when an abnormality occurs in the machine tool during the machining of a workpiece and the machining stops, the tool can be returned along the machining path by the reverse function. When the tool is returned to a position where the tool does not contact the workpiece by the reverse function, an operator can move the tool to a tool change position, for example, by manual operation.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Laid-Open No. 2-155004 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] However, in a conventional machine tool, when using the reverse function, an operator needs to refer to a machining program to confirm a non-cutting section where the tool does not contact the workpiece, such as a rapid feed section. Alternatively, the operator needs to visually confirm the movement of the tool while returning the tool to a position where the tool does not contact the workpiece. Therefore, the operation time of the operator when performing the operation of returning the tool along the machining path is long. As a result, the operation time of the machine tool may be shortened and the productivity may be reduced.

[0008] An object of the present invention is to provide a numerical control device, a machine tool, and a control method for a machine tool that can reduce the operation time of an operator when the tool moves backward.

[0009] Means for Solving the Problems

[0010] The numerical control device includes: an extraction unit that extracts at least one non-cutting section where the tool does not contact the workpiece in a tool path along which the tool moves, based on sensor information indicating a physical quantity detected by a sensor; a setting unit that sets an end position of a reverse movement in which the tool moves backward along the tool path in one of the at least one non-cutting sections extracted by the extraction unit; and a control unit that controls the reverse movement.

[0011] The control method for a machine tool includes: extracting at least one non-cutting section where the tool does not contact the workpiece in a tool path along which the tool moves, based on sensor information indicating a physical quantity detected by a sensor; setting an end position of a reverse movement in which the tool moves backward along the tool path in one of the at least one non-cutting sections extracted; and controlling the reverse movement.

[0012] Advantages of the Invention

[0013] According to the present invention, it is possible to reduce the working time of an operator when the tool is reversed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 An example of the hardware structure of a machine tool is shown.

[0015] Figure 2 It is a block diagram showing an example of the functions of a numerical control device.

[0016] Figure 3 An example of the display of the tool path displayed on the display device is shown.

[0017] Figure 4 An example of the end position of the reverse operation is explained.

[0018] Figure 5 An example of the process executed during the cutting of a workpiece is explained.

[0019] Figure 6 An example of the process performed when the cutting of the workpiece is aborted during the execution of the machining program is explained.

[0020] Figure 7 An example of the display of the tool path displayed on the display device when extracting a plurality of non-cutting sections is explained.

[0021] Figure 8 An example of the prompting unit causing the display device to display various information is explained. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0023] Figure 1 An example of the hardware structure of the machine tool according to this embodiment is shown. The machine tool 1 is a machine for machining a workpiece using a tool. The machine tool 1 uses tools such as end mills, cutting tools, and drills to machine the workpiece. The machine tool 1 is, for example, a machining center, a lathe, a drill press, or a compound machining machine.

[0024] The machine tool 1 includes a numerical control device 2, a display device 3, an input device 4, a servo amplifier 5 and a servo motor 6, a spindle amplifier 7 and a spindle motor 8, a sensor 9, and peripheral equipment 10.

[0025] The numerical control device 2 is a device that controls the entire machine tool 1.

[0026] The numerical control device 2 includes a CPU (Central Processing Unit), a bus 12, a ROM (Read Only Memory) 13, a RAM (Random Access Memory) 14, and a non-volatile memory 15.

[0027] The CPU 11 is a processor that controls the entire numerical control device 2 according to the system program. The CPU 11 reads out the system program and the like stored in the ROM 13 via the bus 12. In addition, the CPU 11 controls the servo motor 6, the spindle motor 8, etc. according to the machining program to perform the cutting process of the workpiece.

[0028] The bus 12 is a communication path that connects the various hardware components within the numerical control device 2. The various hardware components within the numerical control device 2 exchange data via the bus 12.

[0029] The ROM 13 is a storage device that stores the system program for controlling the entire numerical control device 2, the analysis program for analyzing various data, and the like.

[0030] The RAM 14 is a storage device that temporarily stores various data. The RAM 14 temporarily stores data related to the tool path calculated by parsing the machining program, display data, data input from the outside, etc. The RAM 14 functions as a working area for the CPU 11 to process various data.

[0031] The non-volatile memory 15 is a storage device that retains data even when the power supply of the machine tool 1 is cut off and the numerical control device 2 is not powered. The non-volatile memory 15 is constituted by, for example, an SSD (Solid State Drive). The non-volatile memory 15 stores, for example, information related to tool specifications such as the tool diameter input from the input device 4, information related to tool correction, information related to tool life, and the machining program.

[0032] The numerical control device 2 further includes a first interface 16, a second interface 17, an axis control circuit 18, a spindle control circuit 19, a third interface 20, a PLC (Programmable Logic Controller) 21, and an I / O unit 22.

[0033] The first interface 16 is an interface that connects the bus 12 to the display device 3. The first interface 16 sends various data processed by the CPU 11 to the display device 3, for example.

[0034] The display device 3 is a device that receives various data via the first interface 16 and displays various data. The display device 3, for example, displays the machining program stored in the non-volatile memory 15, information related to tool correction, and the like. The display device 3 is a display such as an LCD (Liquid Crystal Display).

[0035] The second interface 17 is an interface that connects the bus 12 and the input device 4. The second interface 17, for example, sends the data input from the input device 4 to the CPU 11 via the bus 12.

[0036] The input device 4 is a device for inputting various data. The input device 4, for example, accepts the input of information related to tool correction and information related to the specifications of the tool, and sends the input data to the non-volatile memory 15 via the second interface 17. The input device 4 is, for example, a keyboard and a mouse. In addition, the input device 4 and the display device 3 may also be configured as one device such as a touch panel, for example.

[0037] The axis control circuit 18 is a control circuit that controls the servo motor 6. The axis control circuit 18 receives a control instruction from the CPU 11 and outputs an instruction for driving the servo motor 6 to the servo amplifier 5. The axis control circuit 18, for example, sends a torque command for controlling the torque of the servo motor 6 to the servo amplifier 5. In addition, the axis control circuit 18 may also send a rotational speed command for controlling the rotational speed of the servo motor 6 to the servo amplifier 5.

[0038] The servo amplifier 5 receives an instruction from the axis control circuit 18 and supplies power to the servo motor 6.

[0039] The servo motor 6 is a motor that is driven by receiving power supply from the servo amplifier 5. The servo motor 6 is, for example, connected to the ball screw that drives the turret, the spindle head, and the worktable. By driving the servo motor 6, components of the machine tool 1 such as the turret, the spindle head, and the worktable move, for example, in the X-axis direction, the Y-axis direction, or the Z-axis direction.

[0040] The spindle control circuit 19 is a control circuit for controlling the spindle motor 8. The spindle control circuit 19 receives a control instruction from the CPU 11 and outputs an instruction for driving the spindle motor 8 to the spindle amplifier 7. The spindle control circuit 19, for example, sends a torque command for controlling the torque of the spindle motor 8 to the spindle amplifier 7. In addition, the spindle control circuit 19 may also send a rotational speed command for controlling the rotational speed of the spindle motor 8 to the spindle amplifier 7.

[0041] The spindle amplifier 7 receives an instruction from the spindle control circuit 19 and supplies power to the spindle motor 8.

[0042] The main shaft motor 8 is a motor that is driven by receiving power supply from the main shaft amplifier 7. The main shaft motor 8 is connected to the main shaft and rotates the main shaft.

[0043] The third interface 20 is an interface that connects the bus 12 and the sensor 9. The third interface 20 sends data representing various physical quantities detected by the sensor 9 to the CPU 11 via the bus 12.

[0044] The sensor 9 is arranged in each component of the machine tool 1 and detects various physical quantities from each component. The sensor 9 is, for example, a current detection sensor, a sound detection sensor, an AE (Acoustic Emission) sensor, an acceleration sensor, or a position detection sensor.

[0045] The current detection sensor is arranged, for example, in the servo motor 6 and the main shaft motor 8, and detects the current supplied to the servo motor 6 and the main shaft motor 8.

[0046] The sound detection sensor detects, for example, the magnitude of the sound in the machining area of the machine tool 1.

[0047] The AE sensor detects, for example, the elastic waves released from the workpiece during cutting.

[0048] The acceleration sensor is arranged, for example, near the main shaft and detects the vibration generated near the main shaft.

[0049] The position detection sensor detects the positions of components of the machine tool 1 such as the turret, the spindle head, and the worktable. The axis control circuit 18 can perform feedback control using the sensor data detected by the position detection sensor.

[0050] In addition, the position detection sensor can also be a position encoder that detects the rotation angle of the main shaft. The position encoder outputs feedback pulses according to the rotation angle of the main shaft. The main shaft control circuit 19 can perform feedback control using the feedback pulses output from the position encoder.

[0051] The PLC 21 is a control device that executes a ladder program to control the peripheral device 10. The PLC 21 controls the peripheral device 10 via the I / O unit 22.

[0052] The I / O unit 22 is an interface that connects the PLC 21 and the peripheral device 10. The I / O unit 22 sends the instructions received from the PLC 21 to the peripheral device 10.

[0053] The peripheral device 10 is arranged on the machine tool 1 and is a device that performs auxiliary operations when machining a workpiece on the machine tool 1. The peripheral device 10 can also be a device arranged around the machine tool 1. The peripheral device 10 is, for example, a tool changing device and a robot such as a manipulator.

[0054] Next, the functions of the numerical control device 2 will be described.

[0055] Figure 2 It is a block diagram showing an example of the functions of the numerical control device 2. The numerical control device 2 includes, for example, a control unit 31, a sensor information acquisition unit 32, a storage unit 33, an extraction unit 34, a presentation unit 35, a reception unit 36, and a setting unit 37.

[0056] The control unit 31, the sensor information acquisition unit 32, the extraction unit 34, the presentation unit 35, the reception unit 36, and the setting unit 37 are realized, for example, by the CPU 11 performing arithmetic processing using the system program and various data stored in the ROM 13. The CPU 11 uses the RAM 14 as a work area to execute the arithmetic processing. In addition, the storage unit 33 is realized by storing the data input from the input device 4 or the like or the arithmetic result of the arithmetic processing of the CPU 11 in the RAM 14 or the non-volatile memory 15.

[0057] The control unit 31 controls, for example, the servo motor 6 and the spindle motor 8 to perform cutting of the workpiece.

[0058] The control unit 31 analyzes the machining program, calculates the tool path along which the tool moves during cutting, the speed of the feed axis of the tool (feed speed), and the rotational speed of the spindle. The control unit 31 rotates the spindle at the calculated rotational speed, and controls the servo motor 6 and the spindle motor 8 so that the tool moves along the calculated tool path at the calculated feed speed. Thereby, cutting is performed.

[0059] The sensor information acquisition unit 32 acquires sensor information indicating various physical quantities detected by the sensor 9. The sensor information acquisition unit 32, for example, acquires information related to the current value of the current supplied to the servo motor 6 or the spindle motor 8 from the current detection sensor. That is, the sensor information is information indicating the load of motors such as the servo motor 6 or the spindle motor 8.

[0060] In addition, the sensor information acquisition unit 32 may acquire information related to the volume in the machining area detected by the sound detection sensor. In addition, the sensor information acquisition unit 32 may acquire information related to the elastic wave acquired by the AE sensor.

[0061] The storage unit 33 stores various information. The storage unit 33 stores, for example, information indicating the tool path during cutting. The information indicating the tool path is, for example, the movement path of the tool tip during cutting, and is composed of a set of data representing coordinate values.

[0062] In addition, the storage unit 33 stores information that correlates the sensor information acquired by the sensor information acquisition unit 32 with the information indicating the tool path. This information is, for example, information that correlates the coordinate values of the positions passed by the tool during the cutting process of the workpiece with the sensor information acquired when the tool passes through the positions indicated by the coordinate values. In addition, the cutting process includes when the tool moves according to the machining program, when the tool moves by cutting feed, and when the tool moves by rapid feed during the positioning operation of the tool, etc.

[0063] In addition, the storage unit 33 may store information related to the specifications of the tool and information related to the shape of the workpiece. Information related to the specifications of the tool is, for example, information indicating the tool diameter of the tool.

[0064] The extraction unit 34 extracts the non-cutting section and the cutting section in the tool path during the cutting process.

[0065] The non-cutting section refers to the section where the tool does not contact the workpiece during the execution of the machining program. The non-cutting section may also be a section where the tool moves by cutting feed and the tool does not contact the workpiece. In addition, the non-cutting section may also include a section where the tool moves by rapid feed and the tool does not contact the workpiece.

[0066] The cutting section refers to the section where the tool contacts the workpiece and cuts the workpiece through the tool during the execution of the machining program.

[0067] The extraction unit 34 extracts the cutting section and the non-cutting section on the tool path based on the information stored in the storage unit 33 that correlates the sensor information with the information indicating the tool path.

[0068] In the case where the sensor information is, for example, information indicating the current value detected by the current detection sensor, the extraction unit 34 extracts the section where the current value exceeds a preset threshold as the cutting section. In addition, the extraction unit 34 extracts the section where the current value is below the preset threshold as the non-cutting section. That is, the extraction unit 34 extracts the section without cutting load and where the torque of the servo motor 6 or the spindle motor 8 is lower than during cutting as the non-cutting section.

[0069] In addition, the extraction unit 34 may also extract the cutting section and the non-cutting section based on the information indicating the detection value detected by the sound detection sensor or the AE sensor.

[0070] The extraction unit 34 causes the storage unit 33 to store the information for determining the non-cutting section on the tool path. The information for determining the non-cutting section includes the information indicating the coordinate values of the non-cutting section.

[0071] The prompting unit 35 prompts the operator with a tool path including a cutting section and a non-cutting section extracted by the extraction unit 34. For example, the prompting unit 35 causes the display device 3 to display information related to the tool path.

[0072] Here, the information related to the tool path displayed on the display device 3 will be described.

[0073] Figure 3 An example of the display of the tool path displayed on the display device 3 will be described.

[0074] Figure 3 The shown tool path is a path that sequentially connects the positions P0, P1, P2, P3, P4, and P5. The tool path from the position P0 to the position P3 and the tool path between the positions P4 and P5 are shown by solid lines and represent the cutting section Sm. The tool path between the positions P3 and P4 is shown by a dashed line and represents the non-cutting section Sn. At the position P5, some event occurred in the machine tool 1, whereby the workpiece machining by the tool T was aborted. Here, some event is, for example, the detection of breakage of the tool T.

[0075] Return Figure 2 The accepting unit 36 accepts information for determining the non-cutting section Sn that is prompted to the user by the prompting unit 35 and selected by the user. For example, when the user selects the non-cutting section Sn displayed on the display device 3 on the display device 3, the accepting unit 36 accepts the information for determining the selected non-cutting section Sn.

[0076] The setting unit 37 sets an end position of the reverse movement in which the tool T moves backward along the tool path in the non-cutting section Sn selected by the user. For example, the setting unit 37 sets, as the end position, a position that is at a predetermined distance from the position P4 where the cutting section Sm switches to the non-cutting section Sn when the tool T performs the reverse movement.

[0077] Figure 4 An example of the end position of the reverse movement will be described. In Figure 4 , a position that is at a predetermined distance D from the position P4 where the cutting section Sm switches to the non-cutting section Sn is set as the end position PE. Regarding the predetermined distance D, it is set, for example, based on a value representing the predetermined distance D input to the input device 4.

[0078] In addition, the predetermined distance D is set, for example, based on the specification information of the tool T stored in the storage unit 33. The predetermined distance D is, for example, a value obtained by multiplying the tool diameter of the tool by a predetermined real number.

[0079] When the end position PE of the reverse operation is set by the setting unit 37, the control unit 31 controls the servo motor 6 and the spindle motor 8 to reversely operate the tool T to the end position PE. When the tool reaches the end position PE, for example, the tool T is retracted from the workpiece W by a manual operation of the user, and the tool T is replaced.

[0080] Next, the processing executed in the numerical control device 2 during the cutting process of the workpiece W will be described.

[0081] Figure 5 An example of the processing executed during the cutting process of the workpiece W will be described.

[0082] The control unit 31 analyzes the machining program and calculates the tool path (step SA01).

[0083] Next, the control unit 31 controls the servo motor 6 and the spindle motor 8 based on the machining program to perform the cutting process of the workpiece W (step SA02).

[0084] During the cutting process of the workpiece W, the sensor information acquisition unit 32 acquires sensor information indicating the physical quantity detected by the sensor 9. In addition, the storage unit 33 stores information that correlates the sensor information acquired by the sensor information acquisition unit 32 with the information indicating the tool path.

[0085] Next, the control unit 31 determines whether the cutting process of the workpiece W has ended (step SA03). If the cutting process of the workpiece W has ended (if it is "yes" in step SA03), the process ends. If the cutting process of the workpiece W has not ended (if it is "no" in step SA03), the control unit 31 continues the cutting process of the workpiece W (step SA02).

[0086] Next, the processing executed when the cutting process is aborted due to an event occurring during the execution of the machining program will be described.

[0087] Figure 6 An example of the processing performed when the cutting process is aborted during the execution of the machining program will be described.

[0088] When the machining of the workpiece W by the tool T is aborted, the extraction unit 34 extracts the non-cutting section Sn based on the information stored in the storage unit 33 that correlates the sensor information with the information indicating the tool path (step SB01).

[0089] Next, the prompting unit 35 prompts the user with the non-cutting section Sn (step SB02).

[0090] Next, the accepting unit 36 accepts the information for determining the non-cutting section Sn selected by the user (step SB03).

[0091] Next, the setting unit 37 sets the end position PE based on the information for determining the non-cutting section Sn received by the receiving unit 36 (step SB04).

[0092] Next, the control unit 31 reversely operates the tool to the end position PE determined by the setting unit 37 (step SB05). If the tool reaches the end position PE, this process ends.

[0093] As described above, the numerical control device 2 of the present embodiment includes: an extraction unit 34 that extracts, based on sensor information representing a physical quantity detected by the sensor 9, a non-cutting section Sn in which the tool T does not contact the workpiece W in the tool path along which the tool T moves; a setting unit 37 that sets an end position of a reverse operation in which the tool T moves reversely along the tool path in the non-cutting section Sn extracted by the extraction unit 34; and a control unit 31 that controls the reverse operation.

[0094] Therefore, the tool T can be automatically and reliably moved to a position where the tool T does not contact the workpiece W. As a result, the operation time of the user when reversing the tool T can be reduced. In addition, regardless of the proficiency of the user (operator), the possibility of adversely affecting the machined surface when reversing the tool T can be reduced. Also, regardless of the proficiency of the user, the possibility of collision between the tool T and the workpiece W when reversing the tool T can be reduced.

[0095] In addition, the numerical control device 2 further includes a receiving unit 36 that receives information for determining the non-cutting section Sn selected by the user, and the setting unit 37 sets the end position PE in the non-cutting section Sn based on the information received by the receiving unit 36.

[0096] Therefore, the tool T can be automatically and reliably moved to a position where the tool T does not contact the workpiece W. As a result, the operation time of the user when reversing the tool T can be reduced.

[0097] In addition, in the present embodiment, the end position PE is a position at a predetermined distance D from the position P4 where the cutting section Sm is switched to the non-cutting section Sn when the tool T performs a reverse operation, and the receiving unit 36 also receives information representing the predetermined distance D.

[0098] Therefore, the user can set at which position in the non-cutting section Sn the tool T stops. As a result, the operation time of the user when reversing the tool T can be reduced.

[0099] In addition, in the present embodiment, the receiving unit 36 receives specification information representing the specifications of the tool T and determines the end position based on the specification information. Therefore, each tool can be stopped at an appropriate position.

[0100] In addition, in the present embodiment, information indicating the load of the motor of the machine tool 1 is used as the sensor information. Therefore, the numerical control device 2 can reliably detect the non-cutting section Sn.

[0101] In addition, in the above embodiment, an example in which the extraction unit 34 extracts one non-cutting section Sn from the tool path has been described, but a plurality of non-cutting sections Sn may also be extracted.

[0102] Figure 7 An example of the display of the tool path displayed on the display device 3 in the case where a plurality of non-cutting sections Sn are extracted will be described.

[0103] In Figure 7 In the example shown, the extraction unit 34 extracts the non-cutting section Sn1 and the non-cutting section Sn2 from the tool path, and the prompting unit 35 prompts the non-cutting section Sn1 and the non-cutting section Sn2.

[0104] When the prompting unit 35 causes the display device 3 to display such a tool path, the user selects one of the non-cutting sections Sn1 and Sn2, i.e., Sn1 or Sn2. Thereby, the accepting unit 36 accepts information related to the selected non-cutting section Sn1 or non-cutting section Sn2. After that, the setting unit 37 sets the end position PE in the selected non-cutting section Sn1 or non-cutting section Sn2.

[0105] That is, the user can select one of the plurality of non-cutting sections Sn1 and Sn2 extracted by the extraction unit 34, i.e., Sn1 or Sn2, considering the case where the tool T retreats from the workpiece W.

[0106] In addition, the prompting unit 35 may, for example, also cause the display device 3 to display information such as the shape of the uncut portion of the fixture and the workpiece, and various information such as the tool change position.

[0107] Figure 8 An example in which the prompting unit 35 causes the display device 3 to display various information will be described. In Figure 8 In the example shown, on the display device 3, information related to the tool J and the tool change position PTE is displayed together with the tool path.

[0108] Thereby, the user can select the non-cutting sections Sn1 and Sn2 considering the position and shape of the fixture J and the tool change position PTE.

[0109] In Figure 8In the example shown, there is a fixture J between the non-cutting section Sn1 and the tool change position PTE. At this time, if the tool T is to be moved to the tool change position PTE by manual operation, the tool T and the fixture J may collide. On the other hand, there is no obstructive part between the non-cutting section Sn2 and the tool change position PTE. Therefore, even if the tool T is moved to the tool change position PTE by manual operation, the tool T and the fixture J will not collide.

[0110] In addition, when various information such as information related to the fixture J and the tool change position PTE is stored in the storage unit 33, the control unit 31 can also select an appropriate non-cutting section Sn from among the multiple non-cutting sections Sn. In this case, the control unit 31 can select the non-cutting section Sn for setting the end position PE based on data such as the positional relationship between the non-cutting section Sn and the tool change position PTE, the fixture J, and the shape of the unprocessed part of the workpiece.

[0111] Description of Reference Numerals

[0112] 1 Machine tool

[0113] 2 Numerical control device

[0114] 3 Display device

[0115] 4 Input device

[0116] 5 Servo amplifier

[0117] 6 Servo motor

[0118] 7 Spindle amplifier

[0119] 8 Spindle motor

[0120] 9 Sensor

[0121] 10 Peripheral equipment

[0122] 11 CPU

[0123] 12 Bus

[0124] 13 ROM

[0125] 14 RAM

[0126] 15 Non-volatile memory

[0127] 16 First interface

[0128] 17 Second interface

[0129] 18 Axis control circuit

[0130] 19 Spindle control circuit

[0131] 20 Third interface

[0132] 21 PLC

[0133] 22 I / O unit

[0134] 31 Control unit

[0135] 32 Sensor information acquisition unit

[0136] 33 Storage unit

[0137] 34 Extraction unit

[0138] 35 Presentation unit

[0139] 36 Reception unit

[0140] 37 Setting unit

[0141] Positions of P0, P1, P2

[0142] Positions of P3, P4, P5

[0143] PE end position

[0144] Sm cutting interval

[0145] Sn non-cutting interval

[0146] Sn1, Sn2 non-cutting intervals

[0147] T Tool

[0148] W Workpiece

[0149] J Fixture

[0150] PTE tool change position.

Claims

1. A numerical control device, characterized in that, Comprising: An extraction unit that extracts at least one non-cutting section in a tool path along which a tool moves, where the tool does not contact a workpiece, based on sensor information representing a physical quantity detected by a sensor; A setting unit that sets an end position of a reverse movement in which the tool moves in reverse along the tool path in one non-cutting section among the at least one non-cutting section extracted by the extraction unit; A control unit that controls the reverse movement; and A receiving unit that receives information for determining the one non-cutting section selected by a user among the at least one non-cutting section, wherein the setting unit sets the end position in the one non-cutting section based on the information received by the receiving unit.

2. The numerical control device according to claim 1, wherein the end position is a position at a predetermined distance from a position where a cutting section switches to the non-cutting section when the tool performs the reverse movement, and the receiving unit further receives information representing the predetermined distance.

3. The numerical control device according to claim 1, wherein the receiving unit further receives specification information representing the specification of the tool, and determines the end position based on the specification information.

4. The numerical control device according to any one of claims 1 to 3, wherein the at least one non-cutting section includes a plurality of non-cutting sections.

5. The numerical control device according to any one of claims 1 to 3, wherein the sensor information is information representing the load of a motor of a machine tool.

6. The numerical control device according to any one of claims 1 to 3, wherein the extraction unit extracts the non-cutting section from a section in the tool path where the tool moves by cutting feed.

7. A machine tool, characterized in that the machine tool has the numerical control device according to any one of claims 1 to 3.

8. A control method for a machine tool, characterized in that, Comprising: Based on sensor information representing a physical quantity detected by a sensor, extracting at least one non-cutting section in a tool path along which a tool moves, where the tool does not contact a workpiece; Setting an end position of a reverse movement in which the tool moves in reverse along the tool path in one non-cutting section among the at least one extracted non-cutting section; Controlling the reverse movement; And Receiving information for determining the one non-cutting section selected by a user among the at least one non-cutting section, Based on the received information, setting the end position in the one non-cutting section.

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