Numerical value controller, method for control, and program

Abstract

To provide a numerical value controller, a method for control, and a program which can reduce power consumption from a servo motor for driving a tool replacement device.SOLUTION: A numerical value controller controls a tool replacement device driven by a replacement motor to replace a tool for a tool magazine. The numerical value controller interrupts power supply to the replacement motor in a stand-dy mode, in which the tool replacement device is not operated. The numerical value controller resumes power supply to the replacement motor when a tool replacement order is output while power supply to the replacement motor is being interrupted, and replaces a tool between the tool replacement device and the tool magazine.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a numerical control device, a control method, and a program.

Background Art

[0002] Patent Document 1 discloses a tool changing device capable of reducing the power consumption of a servo motor that rotates a tool magazine. The tool changing device exchanges tools between the tool magazine and the spindle. The tool magazine has a plurality of tool pods and is rotated by a servo motor. The tool magazine is provided with an electromagnetic brake that operates when the power supply to the servo motor is stopped. When the next tool change command is not output even after a predetermined time has elapsed after the tool magazine has been rotated, the tool changing device interrupts the power supply to the servo motor and operates the electromagnetic brake. When the next tool change command is output, the tool changing device supplies power to the servo motor and the electromagnetic brake stops operating.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In some cases, a tool changing device that can replace tools with a tool magazine is provided together with the tool changing device. When the tool changing device is driven by a servo motor, the servo motor holds the state of the tool changing device even in a standby state where tools are not replaced between the tool changing device and the tool magazine, so power is consumed by the servo motor.

[0005] An object of the present invention is to provide a numerical control device, a control method, and a program capable of reducing the power consumption of a servo motor that drives a tool changing device.

Means for Solving the Problem

[0006] The numerical control device according to the first aspect of the present invention is a numerical control device that controls the operation of a machine tool including a tool magazine capable of loading tools mounted on a spindle and a tool changer capable of replacing the tools with respect to the tool magazine by driving a servo motor, comprising: an interruption unit that interrupts power supply to the servo motor in a standby state where the tool changer is not operated; an output unit that outputs a tool change command for replacing the tool loaded in the tool magazine to the tool changer; and a restart unit that restarts power supply to the servo motor when the output unit outputs the tool change command in a state where power supply to the servo motor has been interrupted by the interruption unit.

[0007] The numerical control device according to the first aspect interrupts power supply to the servo motor when in a standby state where the tool changer is not operated. When the numerical control device acquires a tool change command in a state where power supply to the servo motor has been interrupted, it restarts power supply to the servo motor and performs tool replacement between the tool changer and the tool magazine. Therefore, the numerical control device can reduce the power consumption of the servo motor that drives the tool changer.

[0008] The numerical control device includes a determination unit that determines whether or not the replacement of the tool based on the tool change command has been completed. The interruption unit may interrupt power supply to the servo motor when the determination unit determines that the replacement of the tool has been completed in a state where power supply to the servo motor has been restarted by the restart unit. In the numerical control device, when the replacement of the tool between the tool changer and the tool magazine is completed, power supply to the servo motor is interrupted again. Therefore, the numerical control device can reduce the power consumption of the servo motor that drives the tool changer.

[0009] In a numerical control device, the tool changer may include a sub magazine capable of loading the tool and transporting the tool to a predetermined position, and an arm capable of holding the tool transported to the predetermined position and movable between the sub magazine and the tool magazine. The servo motor may include a first servo motor for driving the sub magazine and a second servo motor for driving the arm. In the numerical control device, power supply to both the first servo motor for driving the sub magazine for transporting the tool to a predetermined position and the second servo motor for driving the arm for changing the tool between the sub magazine and the tool magazine is controlled by an interruption unit and a restart unit. Therefore, the numerical control device can reduce the power consumption of the servo motor for driving the tool changer.

[0010] In a numerical control device, the machine tool further includes a partition wall partitioning between the tool changer and the tool magazine, a shutter movable between an open state for opening an opening provided in the partition wall and a closed state for closing the opening, a drive unit for moving the shutter between the open state and the closed state, and a detection unit for detecting the open state or the closed state of the shutter. When the output unit outputs the tool change command, the numerical control device controls the drive unit to move the shutter to the open state. The arm is movable between the tool magazine and the sub magazine through the opening. The restart unit may restart the power supply to the servo motor when the detection unit detects that the shutter is in the open state or not in the closed state while the power supply to the servo motor is interrupted by the interruption unit. In the numerical control device, when the shutter is in the open state, tool change between the tool changer and the tool magazine is started. In the numerical control device, when it is detected that the shutter is in the open state or not in the closed state, the power supply to the servo motor is restarted. Therefore, the numerical control device can easily control the timing of restarting the power supply to the servo motor.

[0011] In a numerical control device, the machine tool further includes a partition wall that partitions between the tool changer and the tool magazine, a shutter that is movable between an open state in which an opening provided in the partition wall is opened and a closed state in which the opening is closed, a drive unit that moves the shutter between the open state and the closed state, and a detection unit that detects the open state or the closed state of the shutter. When the determination unit determines that the tool replacement is completed, the numerical control device controls the drive unit to move the shutter to the closed state. The arm is movable between the tool magazine and the sub-magazine through the opening. The interruption unit may interrupt the power supply to the servo motor when the detection unit detects that the shutter is in the closed state or not in the open state in a state where the power supply to the servo motor is resumed by the resumption unit. In the numerical control device, when the tool replacement between the tool changer and the tool magazine is completed, the shutter becomes the closed state. In the numerical control device, when it is detected that the shutter is in the closed state or not in the open state, the power supply to the servo motor is interrupted. Therefore, the numerical control device can easily control the timing of interrupting the power supply to the servo motor.

[0012] The numerical control device may include a switching unit that switches between enabling and disabling the interruption of the power supply to the servo motor by the interruption unit. Thereby, the numerical control device can realize specifications according to the machine tool.

[0013] The control method according to the second aspect of the present invention is a control method for controlling the operation of a machine tool including a tool magazine capable of loading a tool mounted on a spindle and a tool changer capable of replacing the tool with respect to the tool magazine by driving a servo motor. In a standby state where the tool changer is not operated, an interruption step of interrupting power supply to the servo motor, an output step of outputting a tool change command for replacing the tool loaded in the tool magazine to the tool changer, and in a state where the power supply to the servo motor is interrupted by the interruption step, when the output step outputs the tool change command, a restart step of restarting the power supply to the servo motor are executed.

[0014] The program according to the third aspect of the present invention causes a computer for controlling the operation of a machine tool including a tool magazine capable of loading a tool mounted on a spindle and a tool changer capable of replacing the tool with respect to the tool magazine by driving a servo motor to execute an interruption process of interrupting power supply to the servo motor in a standby state where the tool changer is not operated, an output process of outputting a tool change command for replacing the tool loaded in the tool magazine to the tool changer, and a restart process of restarting the power supply to the servo motor when the output process outputs the tool change command in a state where the power supply to the servo motor is interrupted by the interruption process.

[0015] The control method according to the second aspect and the program according to the third aspect have the same effects as the numerical control device according to the first aspect.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings used are for explaining the technical features that can be adopted by the present invention. That is, the configurations and the like shown in the drawings are not intended to be limited thereto, but are merely illustrative examples. In the following description, the left - right, front - rear, and up - down directions indicated by arrows in the drawings are used. The left - right direction, front - rear direction, and up - down direction of the machine tool 1 are the X - axis direction, Y - axis direction, and Z - axis direction of the machine tool 1, respectively.

[0018] The machine tool 1 shown in FIG. 1 is a machine that rotates the tool 3 mounted on the spindle 9 and performs cutting on the workpiece (not shown) held by the workpiece holding part 11. The numerical control device 30 (see FIG. 6) controls the operation of the machine tool 1 based on an NC program described later.

[0019] <Structure of the machine tool 1> Referring to FIG. 1, the structure of the machine tool 1 will be described. The machine tool 1 includes a base 2, an XY moving mechanism 10, a work holding part 11, a column 5, a control box 6, an operation panel 15 (see FIG. 6), a Z-axis moving mechanism (not shown), a spindle head 7, a spindle 9, a tool changer 20, and a tool replacement device 4.

[0020] The base 2 is a substantially rectangular parallelepiped-shaped metal base that is long in the front-rear direction. The XY moving mechanism 10 is provided on the upper surface of the base 2 and in front of the column 5, and is movable in the X-axis direction and the Y-axis direction. The work holding part 11 is provided on the upper part of the XY moving mechanism 10 and holds the workpiece to be machined. The work holding part 11 moves in the X-axis direction and the Y-axis direction by the XY moving mechanism 10. The work holding part 11 is rotatable around the A-axis with the left-right direction as the axis direction and around the C-axis with the up-down direction as the axis direction.

[0021] The column 5 is fixed to the rear part of the upper surface of the base 2. The column 5 is a vertical column that extends in the up-down direction. The control box 6 is provided on the back surface of the column 5 and houses a numerical control device 30 described later. The operation panel 15 is provided on the outer wall of a cover (not shown) that covers the machine tool 1, for example, and has an operation part 16 and a display part 17 (see FIG. 6). The operation part 16 receives inputs of various information, various instructions, etc., and outputs them to the numerical control device 30. The display part 17 displays various screens based on commands from the numerical control device 30.

[0022] The Z-axis moving mechanism is provided at the front part of the column 5. The Z-axis moving mechanism is movable in the Z-axis direction. The spindle head 7 (see FIG. 3) is provided at the front part of the column 5 and is box-shaped. The spindle head 7 moves in the Z-axis direction by the Z-axis moving mechanism. The spindle 9 is provided inside the front part of the spindle head 7 and is a cylindrical shape that extends in the up-down direction. The spindle 9 is rotatably supported by the spindle head 7. The lower end part of the spindle 9 can be fitted with a tool 3.

[0023] <Structure of the tool changer 20> Referring to FIG. 1, the structure of the tool changer 20 will be described. The tool changer 20 exchanges the tool 3 mounted on the spindle 9. The tool changer 20 includes a tool magazine 21 and a magazine motor 52 (see FIG. 6). The tool magazine 21 is of the turret type. The tool magazine 21 has a pair of frames (not shown), a support base (not shown), a magazine body 22, and a plurality of grip arms 23.

[0024] One frame of the tool magazine 21 is a plate-shaped member extending forward from the upper part of the left front end of the column 5. The other frame of the tool magazine 21 is a plate-shaped member extending forward from the upper part of the right front end of the column 5. The support base is provided at the front ends of the pair of frames. The support base is located in front of the spindle head 7. The magazine body 22 is provided at the front part of the support base. The magazine body 22 is disk-shaped and is provided facing the front of the machine tool 1. The central axis of the magazine body 22 extends obliquely downward with respect to the front of the machine tool 1. The magazine body 22 rotates about the central axis by the drive of the magazine motor 52.

[0025] Each grip arm 23 is provided at a predetermined interval on the outer periphery of the magazine body 22. Each grip arm 23 is provided swingably in the front-rear direction of the magazine body 22. The tip of the grip arm 23 is detachable from the tool 3. That is, the tool magazine 21 loads the tool 3 by a plurality of grip arms 23.

[0026] <Structure of the tool replacement device 4> Referring to FIGS. 4 and 5, the structure of the tool replacement device 4 will be described. The tool replacement device 4 replaces the tool 3 with respect to the tool magazine 21 of the tool changer 20. The tool replacement device 4 consists of tool replacement devices 4A and 4B. The tool replacement device 4A is provided on one frame of the tool magazine 21. The tool replacement device 4B is provided on the other frame of the tool magazine 21. The tool replacement devices 4A and 4B have a structure symmetric with respect to the left-right direction of the machine tool 1 with respect to the column 5. Hereinafter, the tool replacement device 4A will be described, and the description of the tool replacement device 4B will be omitted.

[0027] The tool replacement device 4A is located behind the tool magazine 21 of the tool changer 20. The tool replacement device 4A has a base (not shown), a support portion 40A, a sub-magazine 41A, an arm 44A, a sub-magazine motor 53, and an arm motor 54. The base is a pedestal that extends leftward from the left end portion of one frame of the tool magazine 21. The support portion 40A is provided at the left end of the base. The support portion 40A is plate-shaped and extends obliquely downward to the right front with respect to the front of the machine tool 1.

[0028] The sub-magazine 41A has a magazine body 42A and a plurality of grip arms 43A. The magazine body 42A is provided at the left portion of the support portion 40A. The magazine body 42A is disk-shaped and is provided facing the front with respect to the left side of the machine tool 1. The central axis of the magazine body 42A extends parallel to the normal direction of the support portion 40A.

[0029] Each grip arm 43A is provided at predetermined intervals on the outer periphery of the magazine body 42A. The tip of the grip arm 43A can attach and detach the tool 3. The sub-magazine 41A loads the tool 3 that is to be replaced with the tool magazine 21 by a plurality of grip arms 43A.

[0030] The arm 44A has a shaft portion 45A and a holding portion 46A. The shaft portion 45A is provided at the upper portion of the support portion 40A and the right portion of the sub-magazine 41A. The shaft portion 45A is parallel to the support portion 40A and extends obliquely downward to the right front with respect to the front of the machine tool 1. Hereinafter, the extending direction of the shaft portion 45A is referred to as the A direction. One of the A directions, the A1 direction, is at the lower right front of the machine tool 1, and the other of the A directions, the A1 direction, is at the upper left rear of the machine tool 1.

[0031] The holding portion 46A is provided at the end portion of the shaft portion 45A in the A1 direction. The holding portion 46A has an air cylinder 461 (see FIG. 6) and a sensor 462 (see FIG. 6) and can hold the tool 3. The holding portion 46A holds the tool 3 when air is supplied to the air cylinder 461, and releases the holding of the tool 3 when air is exhausted from the air cylinder 461. The sensor 462 detects the holding or release of the tool 3 by the air cylinder 461.

[0032] The sub-magazine motor 53 is provided at the right part of the support portion 40A. The magazine main body 42A rotates around the central axis by the drive of the sub-magazine motor 53. The arm motor 54 is provided at the left part of the support portion 40A and on the A2 direction side of the shaft portion 45A. The arm 44A linearly moves in the A direction by the drive of the arm motor 54.

[0033] <Tool replacement device cover> As shown in FIGS. 2 and 3, a pair of tool replacement device covers that cover the tool replacement device 4 are provided on a cover (not shown) that covers the machine tool 1. The pair of tool replacement device covers cover the tool replacement devices 4A and 4B, preventing chips and the like generated during machining of the workpiece from reaching the tool replacement devices 4A and 4B. One of the tool replacement device covers, the tool replacement device cover 60A, covers the tool replacement device 4A. The other tool replacement device cover covers the tool replacement device 4B. Although not shown in FIGS. 2 and 3, the pair of tool replacement device covers has a structure that is symmetric in the left-right direction of the machine tool 1 with respect to the column 5. Hereinafter, the tool replacement device cover 60A will be described, and the description of the other tool replacement device cover will be omitted.

[0034] The tool replacement device cover 60A is box-shaped and covers the left, front, rear, and lower sides of the tool replacement device 4A. The front wall 63A of the tool replacement device cover 60A is orthogonal to the front-rear direction. Although not shown, the front wall 63A is located between the tool magazine 21 of the tool changer 20 and the tool replacement device 4A in the front-rear direction. That is, the front wall 63A partitions between the tool magazine 21 and the tool replacement device 4A. An opening 64A that opens the front wall 63A in the front-rear direction is formed in the front wall 63A. The opening 64A is located on the A1 direction side of the arm 44A. The arm 44A moves between the tool magazine 21 and the sub-magazine 41A through the opening 64A.

[0035] On the front wall 63A, a shutter 61A for opening and closing the opening 64A is provided. The shutter 61A has a cover 62A, an air cylinder 611 (see FIG. 6), and a sensor 612 (see FIG. 6). The cover 62A is a plate having a substantially rectangular shape when viewed from the front. The cover 62A is movable between an open state (see FIG. 3) in which the opening 64A is opened and a closed state (see FIG. 2) in which the opening 64A is closed. In the present embodiment, the open state of the cover 62A is a position above the closed state. The cover 62A is provided with a magnet for detection by a sensor 612 described later.

[0036] The air cylinder 611 moves the cover 62A in the vertical direction, thereby moving the cover 62A between the open state and the closed state. The shutter 61A moves the cover 62A downward to the closed state when air is exhausted from the air cylinder 611, and moves the cover 62A upward to the open state when air is supplied to the air cylinder 611. The sensor 612 detects whether the cover 62A is in the open state or not in the open state. In the present embodiment, the sensor 612 is a magnetic sensor, and detects that the cover 62A is in the open state by detecting the magnetic field of the magnet when the cover 62A is in the open state.

[0037] <Electrical Configuration of the Numerical Control Device 30 and the Machine Tool 1> Referring to FIG. 6, the electrical configuration of the numerical control device 30 and the machine tool 1 will be described. The numerical control device 30 has a CPU 31, a ROM 32, a RAM 33, a storage device 34, an input / output unit 35, and drive circuits 71 to 76. The CPU 31 performs overall control of the numerical control device 30.

[0038] The ROM 32 stores various setting information. The RAM 33 temporarily stores various information. The storage device 34 is non-volatile and stores a plurality of NC programs, a control program for executing main processing (see FIG. 9), etc. The NC program is a machining program composed of multiple lines. Each line of the NC program includes control commands for performing various operations including axis movement of the machine tool 1, tool change between the main spindle 9 and the tool magazine 21, tool change between the tool magazine 21 and the tool changer 4. The numerical control device 30 executes the control commands constituting the NC program in line units and controls the operation of the machine tool 1.

[0039] The input / output unit 35 performs input / output of various signals among the CPU 31, the RAM 33, the storage device 34, the input / output unit 35, the drive circuits 71 to 76, the sensors 462, 612, the operation unit 16, and the display unit 17.

[0040] The drive circuit 71 is connected to the input / output unit 35, the main spindle motor 51, and the encoder 511. The drive circuit 72 is connected to the input / output unit 35, the magazine motor 52, and the encoder 521. The drive circuit 73 is connected to the input / output unit 35, the sub-magazine motor 53, and the encoder 531. The drive circuit 74 is connected to the input / output unit 35, the arm motor 54, and the encoder 541. The drive circuit 75 is connected to the input / output unit 35 and the air cylinder 461. The drive circuit 76 is connected to the input / output unit 35 and the air cylinder 611.

[0041] Based on the commands input from the CPU 31, the drive circuits 71, 72, 73, 74, 75, 76 output drive currents to the main spindle motor 51, the magazine motor 52, the sub-magazine motor 53, the arm motor 54, the air cylinder 461, and the air cylinder 611. The main spindle motor 51, the magazine motor 52, the sub-magazine motor 53, and the arm motor 54 are all servo motors and rotate according to the input drive current.

[0042] The encoders 511, 521, 531, 541 are all absolute value encoders and detect the rotational positions of the main spindle motor 51, the magazine motor 52, the sub-magazine motor 53, and the arm motor 54.

[0043] The encoders 511, 521, 531, 541 output feedback signals indicating the detected rotational positions to the drive circuits 71, 72, 73, 74. The drive circuits 71, 72, 73, 74 perform feedback control on the spindle motor 51, the magazine motor 52, the sub-magazine motor 53, and the arm motor 54 based on the feedback signals. The CPU 31 detects the rotational position of the magazine body 22, the rotational position of the magazine body 42A, and the position of the arm 44A in the A direction based on the feedback signals output from the encoders 521, 531, 541, respectively.

[0044] The sub-magazine motor 53 has a holding brake 532. The arm motor 54 has a holding brake 542. The holding brakes 532, 542 are non-excitation operation type brakes and operate without consuming power.

[0045] The holding brake 532 holds the rotating shaft of the sub-magazine motor 53 when power supply to the sub-magazine motor 53 is not performed, and holds the state of the sub-magazine 41A (the rotational position of the magazine body 42A). The holding brake 532 releases the holding of the rotating shaft of the sub-magazine motor 53 when power supply to the sub-magazine motor 53 is performed, and enables the magazine body 42A to be rotated by the sub-magazine motor 53. When power supply to the sub-magazine motor 53 is performed, the sub-magazine motor 53 is driven based on a command for determining the rotational position of the magazine body 42A, and the state of the sub-magazine 41A is held.

[0046] The holding brake 542 holds the rotating shaft of the arm motor 54 when power is not supplied to the arm motor 54, and holds the state of the arm 44A (the position of the arm 44A in the A direction). The holding brake 542 releases the holding of the rotating shaft of the arm motor 54 when power is supplied to the arm motor 54, and enables the arm 44A to rotate by the arm motor 54. When power is supplied to the arm motor 54, the arm motor 54 is driven based on a command for determining the position of the arm 44A in the A direction, and the state of the sub-magazine 41A is maintained. Hereinafter, the sub-magazine motor 53 and the arm motor 54 of the tool changing device 4A having the holding brakes 532 and 542 are collectively referred to as the changing motor.

[0047] <Tool replacement of Tool 3> With reference to FIG. 7, the replacement of Tool 3 with respect to the tool magazine 21 of the tool changing device 4A will be described. "The replacement of Tool 3 with respect to the tool magazine 21 of the tool changing device 4A" refers to the delivery operation of delivering the Tool 3 loaded in the sub-magazine 41A of the tool changing device 4A to the tool magazine 21 of the tool changer 20, the receiving operation of receiving the Tool 3 loaded in the tool magazine 21 by the Tool 3 loaded in the sub-magazine 41A, or a combination of the delivery operation and the receiving operation.

[0048] When replacing Tool 3 with respect to the tool magazine 21 of the tool changing device 4A, the numerical control device 30 outputs a tool change command. At this time, the arm 44A is located at the initial position in the A direction. The initial position of the arm 44A is a position inside the radial direction of the sub-magazine 41A. In other words, the arm 44A located at the initial position is located inside the gripper arm 43A in the radial direction of the sub-magazine 41A (see FIG. 4).

[0049] When the numerical control device 30 outputs a tool change command, the tool magazine 21 rotates by driving the magazine motor 52. The tool magazine 21 rotates so that one gripper arm 23 specified by the tool change command is disposed at the position P. The position P is the rotational position of the tool magazine 21 that overlaps the tool magazine 21 when the arm 44A located at the initial position extends in the A1 direction.

[0050] When the rotation of the tool magazine 21 is completed, the shutter 61A releases the opening 64A by the drive of the air cylinder 611. When the numerical control device 30 determines by the sensor 612 that the shutter 61A has released the opening 64A, the sub-magazine 41A rotates by the drive of the sub-magazine motor 53. The sub-magazine 41A rotates so that one grip arm 43A designated by the tool replacement command is disposed at the position Q. The position Q is the rotational position of the sub-magazine 41A that overlaps the sub-magazine 41A when the arm 44A located at the initial position extends in the A1 direction.

[0051] In the transfer operation in which the tool changer 4A delivers the tool 3 to the tool magazine 21, the arm 44A moves in the A1 direction from the initial position (see FIG. 7(A)) by the drive of the arm motor 54. The arm 44A holds the tool 3 mounted on the grip arm 43A of the sub-magazine 41A disposed at the position Q by the holding portion 46A (see FIG. 7(B)). When the arm 44A further moves in the A1 direction, the tool 3 held by the holding portion 46A detaches from the grip arm 43A (see FIG. 7(C)). The arm 44A pushes the tool 3 into the grip arm 23 of the tool magazine 21 disposed at the position P and releases the holding of the tool 3 by the holding portion 46A (see FIG. 7(D)). Thereby, the grip arm 23 disposed at the position P mounts the tool 3. The arm 44A moves in the A2 direction by the drive of the arm motor 54 until it is disposed at the initial position (see FIG. 7(E)).

[0052] In the receiving operation where the tool replacement device 4A receives the tool 3 from the tool magazine 21, the arm 44A moves in the A1 direction from the initial position (see Fig. 7(E)) by driving the arm motor 54. The arm 44A holds the tool 3 attached to the grip arm 23 of the tool magazine 21 arranged at the position P by the holding portion 46A (see Fig. 7(D)). When the arm 44A moves in the A2 direction, the tool 3 held by the holding portion 46A detaches from the grip arm 23 (see Fig. 7(C)). The arm 44A pushes the tool 3 into the grip arm 43A of the sub-magazine 41A arranged at the position Q and releases the holding of the tool 3 by the holding portion 46A (see Fig. 7(B)). Thereby, the grip arm 43A arranged at the position Q attaches the tool 3. The arm 44A moves in the A2 direction by driving the arm motor 54 until it is arranged at the initial position (see Fig. 7(A)).

[0053] <Control Mode of Power Supply to the Replacement Motor> Referring to Fig. 8, the control mode of the power supply to the replacement motor will be described. The numerical control device 30 switches between a first mode and a second mode as the control mode of the power supply to the replacement motor. The first mode is a mode in which power supply to the replacement motor is performed when the tool replacement device 4A operates, and power supply to the replacement motor is not performed in the standby state where the tool replacement device 4A does not operate. The second mode is a mode in which power supply to the replacement motor is performed regardless of the state of the tool replacement device 4A. Here, "power supply to the replacement motor" means power supply to the power terminal for receiving the drive current input to rotate the replacement motor. That is, it is only necessary to control the power supply to the power terminal of the replacement motor, and the power supply to the signal terminal for transmitting and receiving signals for controlling the replacement motor may or may not be performed.

[0054] More specifically, in the first mode, when the replacement of the tool 3 with respect to the tool magazine 21 of the tool replacement device 4A is not performed, power supply to the replacement motor is not performed, and the state of the tool replacement device 4A is maintained by the holding brakes 532 and 542.

[0055] When the numerical control device 30 outputs a tool change command to change the tool 3, the tool magazine 21 rotates, and the shutter 61A opens the opening 64A at time T1. When the shutter 61A opens the opening 64A, the holding brakes 532 and 542 are released to operate the tool change device 4A, and the power supply to the change motor is restarted.

[0056] The sub-magazine 41A rotates by driving the sub-magazine motor 53. When the grip arm 43A specified by the tool change command is determined to be at the position Q at time T1, the tool 3 is changed with respect to the tool magazine 21 by the arm 44A. When the arm 44A completes the change of the tool 3 and is arranged at the initial position, the shutter 61A closes the opening 64A at time T2 (>T1). When the shutter 61A closes the opening 64A, it is assumed that the operation of the tool change device 4A is completed, the power supply to the change motor is interrupted, and the holding brakes 532 and 542 operate.

[0057] Since no power is consumed when the holding brakes 532 and 542 operate, the power is consumed by the change motor in the first mode only from time T1 to time T2. And until the change of the tool 3 is started based on the next tool change command, the power supply to the change motor is not performed, and the state of the tool magazine 21 is maintained by the holding brakes 532 and 542.

[0058] In the second mode of one side, since power is supplied to the replacement motor regardless of the state of the tool replacement device 4A, the state of the tool replacement device 4A is maintained by the replacement motor driven based on the feedback signals from the encoders 531 and 541. For example, when the tool 3 is loaded and the sub-magazine 41A rotates from the designated rotational position due to an unbalanced load generated in the sub-magazine 41A. In this case, the drive circuit 73 drives the sub-magazine motor 53 based on the feedback signal to rotate the sub-magazine 41A in the reverse direction so that the sub-magazine 41A reaches the designated rotational position. Also, the arm 44A may shift in the A1 direction from the initial position due to its own weight. In this case, the drive circuit 74 drives the arm motor 54 based on the feedback signal to move the arm 44A in the A2 direction so that the arm 44A reaches the designated position in the A direction. Thus, in the second mode, since the replacement motor is driven to maintain the state of the tool magazine 21, power is constantly consumed by the replacement motor.

[0059] <Main process> Referring to FIGS. 9 and 10, the main process executed by the CPU 31 will be described. The main process starts when the power of the machine tool 1 and the numerical control device 30 is turned on by calling the control program of the main process from the storage device 34 and executing the called control program.

[0060] As shown in FIG. 9, when the main process starts, the CPU 31 determines whether power is being supplied to the spindle motor 51, the magazine motor 52, the sub-magazine motor 53, and the arm motor 54 (S1). For example, when the machine tool 1 stopped abnormally due to an error during the previous use, power may not be supplied to the spindle motor 51, the magazine motor 52, the sub-magazine motor 53, and the arm motor 54 when the power of the machine tool 1 is turned on. If the CPU 31 determines that power is not being supplied to the spindle motor 51, the magazine motor 52, the sub-magazine motor 53, and the arm motor 54 (S1: NO), the process returns to S1.

[0061] When the CPU 31 determines that power is being supplied to the spindle motor 51, the magazine motor 52, the sub-magazine motor 53, and the arm motor 54 (S1: YES), it determines whether a mode change instruction has been received (S2). The mode change instruction is an instruction to switch the mode from the first mode to the second mode or from the second mode to the first mode. The operator inputs the mode change instruction using the operation unit 16 of the operation panel 15.

[0062] When the CPU 31 determines that a mode change instruction has been received (S2: YES), it determines whether the mode is the first mode (S3). When the CPU 31 determines that the mode is the first mode (S3: YES), assuming that the mode is switched from the first mode to the second mode, it resumes power supply to the replacement motor (S4) and releases the operation of the holding brakes 532 and 542. The CPU 31 sets the value of the mode flag to 1 (S5) and returns the process to S2. The value of the mode flag indicates whether the control mode is the first mode or the second mode. When the value of the mode flag is 0, it indicates that the mode is the first mode. When the value of the mode flag is 1, it indicates that the mode is the second mode.

[0063] When the CPU 31 determines that the mode is not the first mode (S3: NO), assuming that the mode is switched from the second mode to the first mode, it interrupts power supply to the replacement motor (S6) and operates the holding brakes 532 and 542. The holding brakes 532 and 542 hold the state of the tool magazine 21. The CPU 31 sets the value of the mode flag to 0 (S5) and returns the process to S2.

[0064] When the CPU 31 determines that a mode change instruction has not been received (S2: NO), it determines whether a machining start instruction has been received (S11). The machining start instruction is an instruction to machine the workpiece. The operator inputs the machining start instruction using the operation unit 16 of the operation panel 15. When the CPU 31 determines that a machining start instruction has not been received (S11: NO), it returns the process to S2.

[0065] When the CPU 31 determines that it has received an instruction to start processing (S11: YES), it reads one NC program specified from a plurality of NC programs stored in the storage device 34 (S12). When the workpiece is being machined, if the control mode is the first mode, the holding brakes 532 and 542 hold the state of the tool magazine 21, and if the control mode is the second mode, the replacement motor holds the state of the tool magazine 21.

[0066] The CPU 31 interprets a control command for one line from the read NC program (S13). The CPU 31 determines whether the interpreted control command is an end command (S14). The end command is a control command that ends the execution of the NC program. When the CPU 31 determines that the interpreted control command is not an end command (S14: NO), it determines whether the interpreted control command is a tool replacement command (S15). When the CPU 31 determines that the interpreted control command is a tool replacement command (S15: YES), it outputs the tool replacement command to the tool replacement device 4A (S16) and transfers the process to S21 (see FIG. 10).

[0067] As shown in FIG. 10, the CPU 31 raises the spindle 9 to the ATC origin by the Z-axis movement mechanism (S21). The ATC origin is the position of the spindle 9 for rotating the tool magazine 21. The CPU 31 drives the magazine motor 52 to rotate the tool magazine 21 (S22). The CPU 31 rotates the tool magazine 21 so that the tool 3 specified by the tool replacement command is located at position P.

[0068] The CPU 31 drives the air cylinder 611 to start opening the aperture 64A by the shutter 61A (S23). The CPU 31 determines whether the opening of the aperture 64A is completed (S24). In the determination of S24, the CPU 31 determines that the opening of the aperture 64A is completed when the sensor 612 detects that the cover 62A is in the open state. When the CPU 31 determines that the opening of the aperture 64A is not completed (S24: NO), it returns the process to S24.

[0069] When the CPU 31 determines that the opening of the opening 64A is completed (S24: YES), it determines whether the control mode is the first mode (S25). When the CPU 31 determines that the value of the mode flag is 0 and the control mode is the first mode (S25: YES), it resumes the power supply to the replaced motors (the sub-magazine motor 53 and the arm motor 54) that were interrupted (S26). When the power supply to the replaced motors is resumed, the operations of the holding brakes 532 and 542 are released, so that the sub-magazine 41A can rotate. The CPU 31 transfers the process to S31.

[0070] When the CPU 31 determines that the value of the mode flag is 1 and the mode is not the first mode (S25: NO), it transfers the process to S31. In this case, the mode is the second mode, the power supply to the replaced motors is constantly performed, and the tool magazine 21 can rotate.

[0071] The CPU 31 drives the sub-magazine motor 53 to rotate the magazine body 42A of the sub-magazine 41A (S31). The CPU 31 rotates the sub-magazine 41A so that the tool 3 specified by the tool replacement command is located at the position Q. The CPU 31 drives the arm motor 54 to move the arm 44A in the A direction, and drives the air cylinder 461 to perform the replacement of the tool 3 with respect to the tool magazine 21 of the tool replacement device 4A using the holding part 46A (S32).

[0072] The CPU 31 determines whether the replacement of the tool 3 with respect to the tool magazine 21 of the tool replacement device 4A is completed (S33). When the replacement of the tool 3 is completed, the arm 44A is located at the initial position (see FIGS. 7(A) and 7(E)). The CPU 31 makes the determination of S33 based on the position of the arm 44A in the A direction specified by the encoder 541. When the CPU 31 determines that the arm 44A is not located at the initial position and the replacement of the tool 3 is not completed (S33: NO), it returns the process to S33.

[0073] When the CPU 31 determines that the arm 44A is in the initial position and the replacement of the tool 3 is completed (S33: YES), it drives the air cylinder 611 to start closing the opening 64A with the shutter 61A (S34). The CPU 31 determines whether the closing of the opening 64A is completed (S35). In the determination of S35, when the sensor 612 detects that the cover 62A is not in the open state, the CPU 31 determines that the closing of the opening 64A is completed. When the CPU 31 determines that the closing of the opening 64A is not completed (S35: NO), it returns the process to S34.

[0074] When the CPU 31 determines that the closing of the opening 64A is completed (S35: YES), it determines whether the control mode is the first mode (S36). When the CPU 31 determines that the value of the mode flag is 0 and the control mode is the first mode (S36: YES), it interrupts the power supply to the replacement motor that has been restarted (S37). When the power supply to the replacement motor is interrupted, the holding brakes 532 and 542 are activated, so the state of the tool changer 4A is held by the holding brakes 532 and 542. The CPU 31 shifts the process to S38.

[0075] When the CPU 31 determines that the value of the mode flag is 1 and the mode is not the first mode (S36: NO), it shifts the process to S38. In this case, the control mode is the second mode, the power supply to the replacement motor is constantly performed, and the state of the tool changer 4A is held by the replacement motor.

[0076] The CPU 31 lowers the spindle 9 arranged at the ATC origin (S38) and shifts the process to S13 (see FIG. 9).

[0077] As shown in FIG. 9, when the CPU 31 determines that the interpreted control command is not a tool change command (S15: NO), it executes various processes based on the control command (S17) and returns the process to S13. The various processes executed in S16 are, for example, the positioning process of the spindle 9, the rotation process of the spindle 9, and the tool change process of exchanging the tool 3 mounted on the spindle 9.

[0078] When the CPU 31 determines that the interpreted control instruction is an end instruction (S14: YES), it ends the machining of the workpiece based on the NC program (S18) and returns the process to S2.

[0079] <Actions and effects of this embodiment> As described above, the numerical control device 30 interrupts the power supply to the replacement motor in the standby state where the tool replacement device 4A is not operated (S6, S37). When the numerical control device 30 outputs a tool replacement command in a state where the power supply to the replacement motor is interrupted (S16), it resumes the power supply to the replacement motor (S26). When the numerical control device 30 is in the standby state where the tool replacement device 4A is not operated, it interrupts the power supply to the replacement motor which is a servo motor. When the numerical control device 30 outputs a tool replacement command, it resumes the interrupted power supply to the replacement motor and performs the replacement of the tool 3 between the tool replacement device 4A and the tool magazine 21. Therefore, the numerical control device 30 can reduce the power consumption of the replacement motor that drives the tool replacement device 4A.

[0080] The numerical control device 30 determines whether the replacement of the tool 3 to the tool magazine 21 of the tool replacement device 4A is completed (S33). When the numerical control device 30 determines that the replacement of the tool 3 is completed, it interrupts the power supply to the replacement motor that has been resumed (S37). In the numerical control device 30, when the replacement of the tool 3 between the tool replacement device 4A and the tool magazine 21 is completed, the power supply to the replacement motor is interrupted again. Therefore, the numerical control device 30 can reduce the power consumption of the replacement motor that drives the tool replacement device 4A.

[0081] The tool replacement device 4A has a sub - magazine 41A and an arm 44A. The replacement motor is a servo motor and includes a sub - magazine motor 53 and an arm motor 54. The sub - magazine 41A rotates by the drive of the sub - magazine motor 53 and rotates until the tool 3 for replacement is placed at the position Q. The arm 44A linearly moves in the A direction by the drive of the arm motor 54. In the numerical control device 30, the supply of power to both the sub - magazine motor 53 that drives the sub - magazine 41A to rotate the tool 3 to the position Q and the arm motor 54 that drives the arm 44A to replace the tool 3 is controlled for interruption and restart. Therefore, the numerical control device 30 can reduce the power consumption of the replacement motor that drives the tool replacement device 4A.

[0082] The front wall 63A of the tool replacement device cover 60A partitions between the tool magazine 21 and the tool replacement device 4A. The shutter 61A opens and closes the opening 64A of the front wall 63A. The arm 44A moves between the tool magazine 21 and the sub - magazine 41A through the opening 64A. The sensor 612 detects the opening and closing of the opening 64A. The numerical control device 30 determines that the opening of the opening 64A is completed when the sensor 612 detects that the cover 62A is in the open state (S24). When the opening of the opening 64A is completed, the numerical control device 30 resumes the power supply to the replacement motor (S26). In the numerical control device 30, when the opening 64A is opened by the shutter 61A, the replacement of the tool 3 for the tool magazine 21 of the tool replacement device 4A is started. In the numerical control device 30, when the sensor 612 detects that the cover 62A is in the open state, the power supply to the replacement motor is resumed. Therefore, the numerical control device 30 can easily control the timing of resuming the power supply to the replacement motor.

[0083] The numerical control device 30 determines that the closing of the opening 64A is completed when the sensor 612 detects that the cover 62A is not in the open state (S35). When the opening 64A is opened, the numerical control device 30 interrupts the power supply to the replacement motor (S37). In the numerical control device 30, when the replacement of the tool 3 with respect to the tool magazine 21 of the tool replacement device 4A is completed, the opening 64A is closed by the shutter 61A. In the numerical control device 30, when the sensor 612 detects that the cover 62A is not in the open state, the power supply to the replacement motor is interrupted. Therefore, the numerical control device 30 can easily control the timing of interrupting the power supply to the replacement motor.

[0084] The numerical control device 30 switches between a first mode (S7) in which the power supply to the replacement motor is interrupted and a second mode (S5) in which the power supply to the replacement motor is constantly supplied. Thereby, the numerical control device 30 can realize a specification suitable for the machine tool 1.

[0085] <Modification example> The present invention can be variously modified from the above embodiment. Each of the various modification examples described below can be combined with each other as long as there is no contradiction. The numerical control device 30 is not limited to being provided in the machine tool 1, and may be provided separately from the machine tool 1. For example, the numerical control device 30 may be a control device (PC, dedicated machine, etc.) electrically connected to the machine tool 1.

[0086] Instead of the CPU 31, for example, a microcomputer, an ASIC (Application Specific Integrated Circuits), an FPGA (Field Programmable Gate Array), etc. may be used for the control of the numerical control device 30. The main processing may be distributedly processed by a plurality of control devices.

[0087] Non-transitory storage media such as the ROM 32 and the storage device 34 may be any storage media capable of retaining information regardless of the period for which the information is stored. The non-transitory storage media may not include transitory storage media (e.g., transmitted signals). The control program for executing the main processing may be downloaded (i.e., transmitted as a transmission signal) from, for example, a server (not shown) connected to a network and stored in the storage device 34. In this case, the control program may be stored in a non-transitory storage media such as an HDD provided in the server.

[0088] The configuration of the machine tool 1 may be changed as appropriate. The machine tool 1 is not limited to an upright machine tool in which the spindle 9 extends vertically, and may be a horizontal machine tool in which the spindle 9 extends horizontally. The direction in which the spindle 9 moves is not limited to the Z-axis direction, and it may be movable in the X-axis direction or the Y-axis direction.

[0089] The tool magazine 21 may convey the tool 3 mounted on the spindle 9 to the tool change position by driving a servo motor. In the above embodiment, the tool magazine 21 is a turret type, but the tool magazine 21 may be, for example, an arm type. The tool magazine 21 rotates by driving the magazine motor 52, but may, for example, translate by driving the magazine motor 52. In the above embodiment, the drive circuits 71 to 76 are provided in the numerical control device 30, but the drive circuits 71 to 76 may be provided in the machine tool 1.

[0090] The configuration of the tool changing device 4 may be changed as appropriate. The tool changing device 4 may be composed only of the tool changing device 4A, or may be composed only of the tool changing device 4B. The tool changing device 4A and the tool changing device 4B do not have to have a symmetrical configuration. The tool changing device 4 may have other tool changing devices in addition to the tool changing devices 4A and 4B. The number of other tool changing devices may be one or plural.

[0091] The tool changer 4 may include a tool changer having a configuration different from that of the tool changers 4A and 4B. The tool changer having a different configuration may be configured, for example, by an arm that replaces the tool 3 with respect to the tool magazine 21. In this case, the tool changer may not have a sub-magazine. The arm of the tool changer may have a configuration different from that of the tool changer, hold the tool 3 from the tool holder that loads the tool 3, and replace the tool 3 with respect to the tool magazine 21.

[0092] The configuration of the sub-magazine 41A of the tool changer 4A may be appropriately changed. Although the sub-magazine 41A is of a turret type, the sub-magazine 41A may be, for example, of an arm type. In the above embodiment, as the operation of the sub-magazine 41A, it rotates by driving the sub-magazine motor 53, but it may, for example, translate by driving the sub-magazine motor 53. The operation of the sub-magazine 41A may combine translational movement and rotational movement. The number of sub-magazine motors 53 for operating the sub-magazine 41A may be plural instead of one.

[0093] The configuration of the arm 44A of the tool changer 4A may be appropriately changed. In the above embodiment, as the operation of the arm 44A, it translates in the A direction by driving the arm motor 54, but it may rotate by driving the arm motor 54. The arm 44A that rotates by driving the arm motor 54 is, for example, a vertically articulated robot arm or a horizontally articulated robot arm. In this case, the number of arm motors 54 is plural. The operation of the arm 44A may combine translational movement and rotational movement. The holding unit 46A holds the tool 3 by driving the air cylinder 461, but it may hold it, for example, by driving a servo motor. In this case, the numerical control device 30 may interrupt or resume the power supply to the servo motor that operates the holding unit 46A at the same timing as the replacement motor.

[0094] When the replacement of the tool 3 with respect to the tool magazine 21 of the tool changer 4A is completed, the numerical control device 30 does not necessarily have to interrupt the power supply to the replacement motor. In the above embodiment, the numerical control device 30 determines that the replacement of the tool 3 is completed when the arm 44A is located at the initial position based on the encoder 541. On the other hand, when a predetermined time has elapsed after the arm motor 54 is driven, it may be determined that the rotation of the tool magazine 21 is completed.

[0095] The machine tool 1 does not necessarily have to have the tool changer cover 60A. The opening 64A may be provided in the wall of the tool changer cover 60A that partitions between the tool magazine 21 and the tool changer 4A, and is not limited to being provided in the front wall 63A. For example, a stepping motor may move the shutter 61A between an open state and a closed state instead of the air cylinder 611.

[0096] Instead of the sensor 612 which is a magnetic sensor, for example, a photoelectric sensor or a microswitch may detect whether the cover 62A is in an open state or not in an open state. In the above embodiment, the sensor 612 detects whether the cover 62A is in an open state or not in an open state, but it may also detect whether the cover 62A is in a closed state or not in a closed state. In this case, in the determination of S24 of the main process, the CPU 31 may determine that the opening 64A is opened when it is detected by the sensor 612 that the cover 62A is not in a closed state. In the determination of S35 of the main process, the CPU 31 may determine that the opening 64A is closed when it is detected by the sensor 612 that the cover 62A is in a closed state.

[0097] The numerical control device 30 may resume the power supply to the replacement motor when the tool replacement command is output. The numerical control device 30 may interrupt the power supply to the replacement motor when the replacement of the tool 3 with respect to the tool magazine 21 of the tool changer 4A is completed.

[0098] In the above embodiment, when the control command interpreted during the execution of the NC program is a tool change command, the numerical control device 30 outputs the tool change command and executes the replacement of the tool 3 in the tool magazine 21 of the tool changer 4A. On the other hand, when the NC program is not being executed, the numerical control device 30 may execute the replacement of the tool 3 when an operator inputs an instruction to replace the tool 3 using the operation unit 16 and the numerical control device 30 accepts it.

[0099] <Others> The replacement motors (sub-magazine motor 53, arm motor 54) are an example of the "servo motor" of the present invention. The CPU 31 that executes the processes of S6 and S37 is an example of the "interrupt section" of the present invention. The processes of S6 and S37 are an example of the "interrupt step" and "interrupt process" of the present invention. The CPU 31 that executes the process of S16 is an example of the "output section". The process of S16 is an example of the "output step" and "output process" of the present invention. The CPU 31 that executes the process of S26 is an example of the "resumption section" of the present invention. The process of S26 is an example of the "resumption step" and "resumption process" of the present invention. The CPU 31 that executes the process of S33 is an example of the "judgment section" of the present invention. The position Q is an example of the "predetermined position" of the present invention. The sub-magazine motor 53 is an example of the "first servo motor" of the present invention. The arm motor 54 is an example of the "second servo motor" of the present invention. The front wall 63A is an example of the "partition wall" of the present invention. The sensor 612 is an example of the "detection section" of the present invention. The CPU 31 that executes the process of S24 is an example of the "release section" of the present invention. The CPU 31 that executes the process of S35 is an example of the "blocking section" of the present invention. The CPU 31 that executes the processes of S4 and S6 is an example of the "switching section" of the present invention.

Explanation of Reference Numerals

[0100] 1 Machine tool 4, 4A, 4B Tool changer 20 Tool exchange device 21 Tool magazine 30 Numerical control device 31 CPU 41A Sub-magazine 44A Arm 53 Sub-magazine motor 532 Holding brake 54 Arm motor 542 Holding brake 60 Tool changer cover 61A Shutter 612 Sensor

Claims

1. A numerical control device for controlling the operation of a machine tool, comprising a tool magazine capable of loading a tool to be mounted on a spindle, and a tool changer capable of replacing the tool with respect to the tool magazine by driving a servo motor, an interruption unit that interrupts power supply to the servo motor in a standby state where the tool changer is not operated, an output unit that outputs a tool change command for replacing the tool loaded in the tool magazine to the tool changer, a restart unit that restarts power supply to the servo motor when the output unit outputs the tool change command while the power supply to the servo motor is interrupted by the interruption unit characterized by comprising.

2. A determination unit for determining whether or not replacement of the tool based on the tool change command is completed is provided, The interruption unit interrupts power supply to the servo motor when the determination unit determines that replacement of the tool is completed while the power supply to the servo motor is restarted by the restart unit The numerical control device according to claim 1, characterized by the above.

3. The tool changer is, a sub magazine capable of loading the tool and transporting the tool to a predetermined position, an arm capable of holding the tool transported to the predetermined position and movable between the sub magazine and the tool magazine, The servo motor is, a first servo motor for driving the sub magazine, a second servo motor for driving the arm The numerical control device according to claim 2, characterized by the above.

4. The machine tool is, a partition wall that partitions between the tool changer and the tool magazine, a shutter movable between an open state in which an opening provided in the partition wall is opened and a closed state in which the opening is closed, a drive unit for moving the shutter between the open state and the closed state, a detection unit for detecting the open state or the closed state of the shutter, and further includes, When the output unit outputs the tool change command, the numerical control device controls the drive unit to move the shutter to the open state, The arm is movable between the tool magazine and the sub magazine through the opening, When the detection unit detects that the shutter is in the open state or not in the closed state while the power supply to the servo motor is interrupted by the interruption unit, the restart unit restarts the power supply to the servo motor. The numerical control device according to claim 3, characterized in that.

5. The machine tool is A partition wall that partitions between the tool changer and the tool magazine, A shutter that is movable between an open state in which an opening provided in the partition wall is opened and a closed state in which the opening is closed, A drive unit that moves the shutter between the open state and the closed state, And a detection unit that detects the open state or the closed state of the shutter, When the determination unit determines that the replacement of the tool is completed, the numerical control device controls the drive unit to move the shutter to the closed state. The arm is movable between the tool magazine and the sub-magazine through the opening. When the detection unit detects that the shutter is in the closed state or not in the open state while the power supply to the servo motor is restarted by the restart unit, the interruption unit interrupts the power supply to the servo motor. The numerical control device according to claim 3, characterized in that.

6. The numerical control device according to claim 1, further comprising a switching unit that switches between enabling and disabling the interruption of the power supply to the servo motor by the interruption unit.

7. A control method for controlling the operation of a machine tool including a tool magazine capable of loading a tool mounted on a spindle and a tool changer capable of replacing the tool with respect to the tool magazine by driving a servo motor. An interruption step of interrupting the power supply to the servo motor in a standby state where the tool changer is not operated, An output step of outputting a tool replacement command for replacing the tool loaded in the tool magazine to the tool changer, A restart step of restarting the power supply to the servo motor when the output step outputs the tool replacement command while the power supply to the servo motor is interrupted by the interruption step A control method characterized by executing.

8. On a computer that controls the operation of a machine tool including a tool magazine capable of loading a tool mounted on a spindle and a tool changer capable of replacing the tool with respect to the tool magazine by driving a servo motor, In a standby state where the tool replacement device is not operated, an interruption process for interrupting power supply to the servo motor, and an output process for outputting a tool replacement command for replacing the tool loaded in the tool magazine to the tool replacement device, and a restart process for restarting power supply to the servo motor when the output process outputs the tool replacement command while the power supply to the servo motor is interrupted by the interruption process A program characterized by executing.

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