Numerical control device, control method, and program

Abstract

The present invention provides a numerical control device, a control method, and a program which make it possible to reduce power consumption by a servo motor that drives a tool change device.　The numerical control device controls the tool change device which is driven by a change motor and which changes a tool on a tool magazine. The numerical control device interrupts the supply of power to the change motor in a standby state in which the tool change device is not operated. Upon output of a tool change command with the supply of power to the change motor interrupted, the numerical control device resumes the interrupted supply of power to the change motor and changes a tool between the tool change device and the tool magazine.

Description

Numerical control device, control method, and program

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

[0002] Patent Document 1 discloses a tool changer that can reduce the power consumption of a servo motor that rotates a tool magazine. The tool changer changes tools between the tool magazine and a spindle. The tool magazine has multiple tool pods and is rotated by a servo motor. The tool magazine is provided with an electromagnetic brake that activates when power supply to the servo motor is stopped. If the next tool change command is not output within a predetermined time after the tool magazine is rotated, the tool changer interrupts the power supply to the servo motor and activates the electromagnetic brake. When the next tool change command is output, the tool changer supplies power to the servo motor and deactivates the electromagnetic brake.

[0003] Japanese Patent Application Laid-Open No. 2002-192434

[0004] In some cases, a tool changer capable of changing tools between the tool changer and the tool magazine is provided in addition to the tool changer. When the tool changer is driven by a servo motor, the servo motor maintains the state of the tool changer even in a standby state where tools are not being changed between the tool changer and the tool magazine, so the servo motor consumes power.

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

[0006] A numerical control device according to a first aspect of the present invention is a numerical control device that controls the operation of a machine tool that includes a tool magazine that can load tools to be attached to a spindle, and a tool changer that can change the tools in the tool magazine by driving a servo motor, and is characterized by comprising: an interruption unit that interrupts the supply of power to the servo motor in a standby state in which the tool changer is not operating; an output unit that outputs a tool change command to the tool changer to change the tools loaded in the tool magazine; and a resumption unit that resumes the supply of power to the servo motor when the output unit outputs the tool change command while the supply of power to the servo motor has been interrupted by the interruption unit.

[0007] The numerical control device of the first aspect interrupts the power supply to the servo motor when the tool changer is in a standby state in which it is not operating. When the numerical control device receives a tool change command while the power supply to the servo motor is interrupted, the numerical control device resumes the power supply to the servo motor and performs a tool change between the tool changer and the tool magazine. Thus, the numerical control device can reduce the power consumption of the servo motor that drives the tool changer.

[0008] The numerical control device may include a determination unit that determines whether the tool change based on the tool change command has been completed, and the interruption unit may interrupt the power supply to the servo motor when the determination unit determines that the tool change has been completed after the resumption unit has resumed power supply to the servo motor. In the numerical control device, when the tool change between the tool changer and the tool magazine is completed, the power supply to the servo motor is interrupted again. Thus, the numerical control device can reduce the power consumption of the servo motor that drives the tool changer.

[0009] In the 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, and the servo motor may include a first servo motor that drives the sub-magazine and a second servo motor that drives the arm. In the numerical control device, an interruption unit and a resumption unit control the supply of power to both the first servo motor that drives the sub-magazine that transports the tool to the predetermined position and the second servo motor that drives the arm that changes the tool between the sub-magazine and the tool magazine. Thus, the numerical control device can reduce the power consumption of the servo motor that drives the tool changer.

[0010] In the numerical control device, the machine tool may further include a partition wall separating the tool changer and the tool magazine, a shutter movable between an open state that opens an opening in the partition wall and a closed state that closes the opening, 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, wherein the numerical control device controls the drive unit to move the shutter to the open state when the output unit outputs the tool change command, and the arm is movable between the tool magazine and the sub-magazine through the opening, and the restart unit may resume the supply of power to the servo motor when the detection unit detects that the shutter is not in the open state or the closed state after the interruption unit has interrupted the supply of power to the servo motor. When the numerical control device detects that the shutter is in the open state or not in the closed state, the power supply to the servo motor is resumed, and therefore the numerical control device can easily control the timing of resuming the power supply to the servo motor.

[0011] In the numerical control device, the machine tool may further include a partition wall separating the tool changer and the tool magazine, a shutter movable between an open state that opens an opening in the partition wall and a closed state that closes the opening, 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, wherein the numerical control device controls the drive unit to move the shutter to the closed state when the determination unit determines that the tool change is complete, the arm is movable between the tool magazine and the sub-magazine through the opening, and the interruption unit interrupts the supply of power to the servo motor when the detection unit detects that the shutter is not in the closed state or the open state after the resumption unit has resumed the supply of power to the servo motor. When the numerical control device detects that the shutter is closed or not open, the power supply to the servo motor is interrupted, so that the numerical control device can easily control the timing of interrupting the power supply to the servo motor.

[0012] The numerical control device may further 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 enabling the numerical control device to achieve specifications suited to the machine tool.

[0013] A control method according to a 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 tools to be attached to a spindle, and a tool changer capable of changing the tools in the tool magazine by driving a servo motor, and is characterized in that the control method includes the following steps in a standby state in which the tool changer is not operating: an interruption step of interrupting the supply of power to the servo motor; an output step of outputting a tool change command to the tool changer to change the tools loaded in the tool magazine; and a restart step of restarting the supply of power to the servo motor when the output step outputs the tool change command in a state in which the supply of power to the servo motor has been interrupted by the interruption step.

[0014] A third aspect of the present invention provides a program for causing a computer that controls the operation of a machine tool including a tool magazine capable of loading tools to be attached to a spindle and a tool changer that can load the tools into the tool magazine by driving a servo motor to execute the following operations: an interruption process for interrupting the supply of power to the servo motor in a standby state in which the tool changer is not operating; an output process for outputting a tool change command to the tool changer to load the tools loaded in the tool magazine; and a resume process for resumed the supply of power to the servo motor when the output process outputs the tool change command in a state in which the supply of power to the servo motor has been 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.

[0016] 1 is a front view of the machine tool 1 with the cover removed. FIG. 2 is a front view of the machine tool 1 with the tool changer 4A covered by the tool changer cover 60A. FIG. 3 is a view of the machine tool 1 in FIG. 2 from the front right. FIG. 4 is a view of the tool changer 4A and the tool magazine 21 when the arm 44A is in the initial position, viewed from the rear right of the machine tool 1. FIG. 5 is a view of the tool changer 4A and the tool magazine 21 when the holding portion 46A of the arm 44A has moved to the tool magazine 21, viewed from the rear right of the machine tool 1. FIG. 6 is a block diagram showing the electrical configuration of the numerical control device 30 and the machine tool 1. FIG. 7 is a view showing the change of a tool 3 to the tool magazine 21 by the tool changer 4A. FIG. 8 is a view showing control of power supply to a changer motor in each of a first mode and a second mode. FIG. 9 is a flowchart showing main processing. FIG. 9 is a flowchart showing main processing, which is a continuation of FIG.

[0017] An embodiment of the present invention will be described below with reference to the drawings. The drawings are used to explain technical features that can be adopted by the present invention. In other words, the configurations and the like shown in the drawings are not intended to be limiting, but are merely illustrative examples. In the following description, left and right, front and rear, and up and down are used as indicated by arrows in the drawings. The left and right direction, front and rear direction, and up and down direction of the machine tool 1 correspond to the X-axis direction, Y-axis direction, and Z-axis direction of the machine tool 1, respectively.

[0018] The machine tool 1 shown in Figure 1 is a machine that rotates a tool 3 attached to a spindle 9 and performs cutting on a workpiece (not shown) held by a workpiece holder 11. A numerical control device 30 (see Figure 6) controls the operation of the machine tool 1 based on an NC program, which will be described later.

[0019] <Structure of Machine Tool 1> The structure of machine tool 1 will be described with reference to Figure 1. Machine tool 1 has a base 2, an XY movement mechanism 10, a workpiece holder 11, a column 5, a control box 6, an operation panel 15 (see Figure 6), a Z-axis movement 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 metal base in the shape of a roughly rectangular parallelepiped that is long in the front-to-rear direction. The XY movement mechanism 10 is provided on the top surface of the base 2 and in front of the column 5, and is movable in the X-axis and Y-axis directions. The workpiece holder 11 is provided on top of the XY movement mechanism 10, and holds the workpiece. The workpiece holder 11 moves in the X-axis and Y-axis directions by the XY movement mechanism 10. The workpiece holder 11 is rotatable around axis A, whose axial direction is the left-right direction, and around axis C, whose axial direction is the up-down direction.

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

[0022] The Z-axis movement mechanism is provided at the front of the column 5. The Z-axis movement mechanism is movable in the Z-axis direction. The spindle head 7 (see FIG. 3) is provided at the front of the column 5 and is box-shaped. The spindle head 7 is moved in the Z-axis direction by the Z-axis movement mechanism. The spindle 9 is provided inside the front of the spindle head 7 and is cylindrical and extends in the vertical direction. The spindle 9 is rotatably supported by the spindle head 7. A tool 3 can be attached to the lower end of the spindle 9.

[0023] <Structure of tool changer 20> The structure of the tool changer 20 will be described with reference to Figure 1. The tool changer 20 changes the tool 3 attached to the spindle 9. The tool changer 20 includes a tool magazine 21 and a magazine motor 52 (see Figure 6). The tool magazine 21 is of a turret type. The tool magazine 21 includes 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 plate-shaped and extends forward from the upper left front end of the column 5. The other frame of the tool magazine 21 is plate-shaped and extends forward from the upper right front end of the column 5. A 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 of the support base. The magazine body 22 is disk-shaped and is provided with its front side facing the front of the machine tool 1. The central axis of the magazine body 22 extends diagonally downward relative to the front of the machine tool 1. The magazine body 22 rotates around its central axis when driven by the magazine motor 52.

[0025] The grip arms 23 are provided at predetermined intervals on the outer periphery of the magazine body 22. Each grip arm 23 is provided so as to be swingable in the front-to-rear direction of the magazine body 22. The tools 3 can be attached and detached to the tip of the grip arm 23. In other words, the tool magazine 21 loads the tools 3 using the multiple grip arms 23.

[0026] <Structure of tool changer 4> The structure of the tool changer 4 will be described with reference to Figures 4 and 5. The tool changer 4 changes tools 3 to the tool magazine 21 of the tool changer 20. The tool changer 4 is made up of tool changers 4A and 4B. The tool changer 4A is provided on one frame of the tool magazine 21. The tool changer 4B is provided on the other frame of the tool magazine 21. The tool changers 4A and 4B are symmetrical in the left-right direction of the machine tool 1 with respect to the column 5. Below, the tool changer 4A will be described, and a description of the tool changer 4B will be omitted.

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

[0028] The sub-magazine 41A has a magazine body 42A and multiple grip arms 43A. The magazine body 42A is provided on the left side of the support part 40A. The magazine body 42A is disk-shaped and is provided with its front facing 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 part 40A.

[0029] The grip arms 43A are provided at predetermined intervals on the outer periphery of the magazine body 42A. The tips of the grip arms 43A can be attached and detached to the tools 3. The sub-magazine 41A is loaded with the tools 3 to be exchanged with the tool magazine 21 by the plurality of grip arms 43A.

[0030] Arm 44A has a shaft portion 45A and a holding portion 46A. Shaft portion 45A is provided on top of support portion 40A and to the right of sub-magazine 41A. Shaft portion 45A is parallel to support portion 40A and extends diagonally downward and to the right relative to the front of machine tool 1. Hereinafter, the extension direction of shaft portion 45A will be referred to as direction A. One of the A directions, direction A1, is the lower-right front of machine tool 1, and the other of the A directions, direction A1, is the upper-left rear of machine tool 1.

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

[0032] The sub-magazine motor 53 is provided on the right side of the support portion 40A. The magazine body 42A rotates around its central axis when driven by the sub-magazine motor 53. The arm motor 54 is provided on the left side of the support portion 40A, on the A2 side of the shaft portion 45A. When driven by the arm motor 54, the arm 44A moves linearly in the A direction.

[0033] <Tool changer cover> As shown in Figures 2 and 3, a pair of tool changer covers for covering the tool changer 4 is provided on a cover (not shown) that covers the machine tool 1. The pair of tool changer covers cover the tool changers 4A, 4B and prevent chips and the like generated during machining of a workpiece from reaching the tool changers 4A, 4B. One of the tool changer covers, tool changer cover 60A, covers the tool changer 4A. The other tool changer cover covers the tool changer 4B. Although not shown in Figures 2 and 3, the pair of tool changer covers are symmetrical in the left-right direction of the machine tool 1 with respect to the column 5. Below, tool changer cover 60A will be described, and a description of the other tool changer cover will be omitted.

[0034] The tool changer cover 60A is box-shaped and covers the left, front, rear, and bottom of the tool changer 4A. The front wall 63A of the tool changer cover 60A is perpendicular to the front-to-rear direction. Although not shown, the front wall 63A is located between the tool magazine 21 of the tool changer 20 and the tool changer 4A in the front-to-rear direction. In other words, the front wall 63A separates the tool magazine 21 from the tool changer 4A. The front wall 63A has an opening 64A that opens the front wall 63A in the front-to-rear direction. 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] A shutter 61A that opens and closes the opening 64A is provided on the front wall 63A. 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 that is generally rectangular when viewed from the front. The cover 62A is movable between an open state (see FIG. 3) that opens the opening 64A and a closed state (see FIG. 2) that closes the opening 64A. In this embodiment, the open state of the cover 62A is located above the closed state. A magnet is provided on the cover 62A for detection by the sensor 612, which will be described later.

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

[0037] <Electrical configuration of numerical control device 30 and machine tool 1> The electrical configuration of the numerical control device 30 and machine tool 1 will be described with reference to Figure 6. The numerical control device 30 has a CPU 31, ROM 32, RAM 33, storage device 34, input / output unit 35, and drive circuits 71 to 76. The CPU 31 controls the numerical control device 30 in an integrated manner.

[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), and the like. The NC program is a machining program consisting of a plurality of lines. Each line of the NC program includes control commands for performing various operations, including axial movement of the machine tool 1, tool exchange between the spindle 9 and the tool magazine 21, and tool exchange between the tool magazine 21 and the tool changer 4. The numerical control device 30 executes the control commands that make up the NC program line by line, and controls the operation of the machine tool 1.

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

[0040] The drive circuit 71 is connected to the input / output unit 35, the 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 commands input from CPU 31, drive circuits 71, 72, 73, 74, 75, and 76 output drive currents to main shaft motor 51, magazine motor 52, sub-magazine motor 53, arm motor 54, air cylinder 461, and air cylinder 611. The main shaft motor 51, magazine motor 52, sub-magazine motor 53, and arm motor 54 are all servo motors, and rotate in response to the input drive current.

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

[0043] Encoders 511, 521, 531, and 541 output feedback signals indicating the detected rotational positions to drive circuits 71, 72, 73, and 74. Based on the feedback signals, drive circuits 71, 72, 73, and 74 perform feedback control on spindle motor 51, magazine motor 52, sub-magazine motor 53, and arm motor 54. Based on the feedback signals output by encoders 521, 531, and 541, CPU 31 detects the rotational position of magazine body 22, the rotational position of magazine body 42A, and the position of arm 44A in direction A, 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 and 542 are non-excitation operation brakes, and operate without consuming power.

[0045] When power is not supplied to the sub-magazine motor 53, the holding brake 532 holds the rotation shaft of the sub-magazine motor 53, thereby maintaining the state of the sub-magazine 41A (the rotational position of the magazine body 42A). When power is supplied to the sub-magazine motor 53, the holding brake 532 releases the hold on the rotation shaft of the sub-magazine motor 53, allowing the magazine body 42A to be rotated by the sub-magazine motor 53. When power is supplied to the sub-magazine motor 53, the sub-magazine motor 53 is driven based on a command that determines the rotational position of the magazine body 42A, thereby maintaining the state of the sub-magazine 41A.

[0046] When power is not supplied to the arm motor 54, the holding brake 542 holds the rotation shaft of the arm motor 54, thereby maintaining the state of the arm 44A (the position of the arm 44A in direction A). When power is supplied to the arm motor 54, the holding brake 542 releases the hold on the rotation shaft of the arm motor 54, allowing 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 that determines the position of the arm 44A in direction A, thereby maintaining the state of the sub-magazine 41A. Hereinafter, the sub-magazine motor 53 and the arm motor 54 of the tool changer 4A having the holding brakes 532 and 542 will be collectively referred to as change motors.

[0047] <Replacement of tools 3> The replacement of tools 3 to the tool magazine 21 of the tool changer 4A will be described with reference to Fig. 7. "Replacement of tools 3 to the tool magazine 21 of the tool changer 4A" refers to a handover operation of transferring the tools 3 loaded in the sub-magazine 41A of the tool changer 4A to the tool magazine 21 of the tool changer 20, a receiving operation of receiving the tools 3 loaded in the tool magazine 21 from the tools 3 loaded in the sub-magazine 41A, or a combination of the handover operation and the receiving operation.

[0048] When changing the tool 3 in the tool magazine 21 of the tool changer 4A, the numerical control device 30 outputs a tool change command. At this time, the arm 44A is positioned at its initial position in the direction A. The initial position of the arm 44A is a position radially inward of the sub-magazine 41A. In other words, the arm 44A positioned at its initial position is positioned radially inward of the grip arm 43A of the sub-magazine 41A (see FIG. 4).

[0049] When the numerical control device 30 outputs a tool change command, the magazine motor 52 rotates the tool magazine 21. The tool magazine 21 rotates so that one grip arm 23 designated by the tool change command is located at position P. Position P is the rotational position of the tool magazine 21 that overlaps with 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 opens the opening 64A by driving the air cylinder 611. When the numerical control device 30 determines by the sensor 612 that the shutter 61A has opened the opening 64A, the sub-magazine motor 53 is driven to rotate the sub-magazine 41A. The sub-magazine 41A rotates so that one grip arm 43A designated by the tool change command is positioned at position Q. Position Q is the rotational position of the sub-magazine 41A at which the arm 44A, positioned at the initial position, overlaps with the sub-magazine 41A when it extends in the A1 direction.

[0051] In the transfer operation in which the tool changer 4A transfers the tool 3 to the tool magazine 21, the arm 44A is driven by the arm motor 54 to move in the direction A1 from the initial position (see FIG. 7A). The arm 44A holds the tool 3 attached to the grip arm 43A of the sub-magazine 41A positioned at position Q with the holding portion 46A (see FIG. 7B). When the arm 44A further moves in the direction A1, the tool 3 held by the holding portion 46A is released from the grip arm 43A (see FIG. 7C). The arm 44A pushes the tool 3 into the grip arm 23 of the tool magazine 21 positioned at position P, releasing the tool 3 from the holding portion 46A (see FIG. 7D). As a result, the grip arm 23 positioned at position P attaches the tool 3. The arm 44A is driven by the arm motor 54 to move in the direction A2 until it is located at the initial position (see FIG. 7E).

[0052] In a receiving operation in which the tool changer 4A receives a tool 3 from the tool magazine 21, the arm 44A is driven by the arm motor 54 to move in the direction A1 from the initial position (see FIG. 7E). The arm 44A holds the tool 3 attached to the grip arm 23 of the tool magazine 21 positioned at position P with the holding portion 46A (see FIG. 7D). When the arm 44A moves in the direction A2, the tool 3 held by the holding portion 46A is released from the grip arm 23 (see FIG. 7C). The arm 44A pushes the tool 3 into the grip arm 43A of the sub-magazine 41A positioned at position Q, thereby releasing the tool 3 from the holding portion 46A (see FIG. 7B). As a result, the grip arm 43A positioned at position Q attaches the tool 3. The arm 44A is driven by the arm motor 54 to move in the direction A2 until it is positioned at the initial position (see FIG. 7A).

[0053] <Control Mode of Power Supply to the Replacement Motor> Referring to FIG. 8 , the control mode of 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 power supply to the replacement motor. In the first mode, power is supplied to the replacement motor when the tool changer 4A is operating, but power is not supplied to the replacement motor when the tool changer 4A is in a standby state and not operating. In the second mode, power is supplied to the replacement motor regardless of the state of the tool changer 4A. Here, "power supply to the replacement motor" refers to power supply to a power terminal for receiving a drive current input to rotate the replacement motor. In other words, it is sufficient to control the power supply to the power terminal of the replacement motor; power may or may not be supplied to a signal terminal for transmitting and receiving signals to control the replacement motor.

[0054] More specifically, in the first mode, when a tool 3 is not being changed to the tool magazine 21 of the tool changer 4A, no power is supplied to the changer motor, and the state of the tool changer 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 changer 4A, and power supply to the change motor is resumed.

[0056] The sub-magazine 41A is rotated by driving the sub-magazine motor 53. When the grip arm 43A specified by the tool change command is indexed to position Q at time T1, the arm 44A changes the tool 3 into the tool magazine 21. When the arm 44A completes the change of the tool 3 and is positioned 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 determined that the operation of the tool changer 4A is complete, the power supply to the change motor is interrupted, and the holding brakes 532 and 542 are activated.

[0057] Since no power is consumed by the operation of the holding brakes 532 and 542, power is consumed by the tool changing motor in the first mode from time T1 to time T2. Then, no power is supplied to the tool changing motor until the next tool change command is issued and the state of the tool magazine 21 is maintained by the holding brakes 532 and 542.

[0058] On the other hand, in the second mode, power is supplied to the tool changer motor regardless of the state of the tool changer 4A. Therefore, the state of the tool changer 4A is maintained by the tool changer motor, which is driven based on feedback signals from the encoders 531 and 541. For example, an unbalanced load on the sub-magazine 41A due to the loading of tools 3 may cause the sub-magazine 41A to rotate from its designated rotation position. In this case, the drive circuit 73 drives the sub-magazine motor 53 based on the feedback signal to reversely rotate the sub-magazine 41A so that the sub-magazine 41A returns to its designated rotation position. Furthermore, the arm 44A may shift in the A1 direction from its 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 returns to its designated A direction position. Thus, in the second mode, the tool changer motor is driven to maintain the state of the tool magazine 21, so power is constantly consumed by the tool changer motor.

[0059] 9 and 10, the main processing executed by the CPU 31 will be described. When the machine tool 1 and the numerical control device 30 are powered on, the main processing starts by calling a control program for the main processing from the storage device 34 and executing the called control program.

[0060] 9, when the main processing starts, CPU 31 determines whether or not power is being supplied to spindle motor 51, magazine motor 52, sub-magazine motor 53, and arm motor 54 (S1). For example, if machine tool 1 was brought to an emergency stop due to an error during the previous use, power may not be being supplied to spindle motor 51, magazine motor 52, sub-magazine motor 53, and arm motor 54 when machine tool 1 is powered on. If CPU 31 determines that power is not being supplied to spindle motor 51, magazine motor 52, sub-magazine motor 53, and arm motor 54 (S1: NO), the processing 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 or not a mode switching instruction has been received (S2). The mode switching instruction is an instruction to switch the current mode to the second mode if the current mode is the first mode, or to switch the current mode to the first mode if the current mode is the second mode. The operator inputs the mode switching instruction using the operation unit 16 of the operation panel 15.

[0062] When the CPU 31 determines that a mode switching 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), it switches the mode from the first mode to the second mode, resumes power supply to the transfer motor (S4), and releases the operation of the holding brakes 532, 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] If the CPU 31 determines that the mode is not the first mode (S3: NO), it switches the mode from the second mode to the first mode, interrupts the power supply to the changing motor (S6), and activates the holding brakes 532, 542. The holding brakes 532, 542 maintain 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] If the CPU 31 determines that a mode switching 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 for machining a workpiece. The operator inputs the machining start instruction using the operation unit 16 of the operation panel 15. If the CPU 31 determines that a machining start instruction has not been received (S11: NO), the process returns to S2.

[0065] When the CPU 31 determines that it has received a machining start command (S11: YES), it reads a specified NC program from the plurality of NC programs stored in the storage device 34 (S12). When machining a workpiece, if the control mode is the first mode, the holding brakes 532, 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 one line of control commands from the read NC program (S13). The CPU 31 determines whether the interpreted control command is an end command (S14). An end command is a control command that terminates execution of an NC program. If 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 change command (S15). If the CPU 31 determines that the interpreted control command is a tool change command (S15: YES), it outputs the tool change command to the tool changer 4A (S16) and proceeds to S21 (see FIG. 10).

[0067] 10, the CPU 31 causes the Z-axis movement mechanism to raise the spindle 9 to the ATC origin (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 designated by the tool change command is indexed to position P.

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

[0069] When the CPU 31 determines that the opening of the opening 64A is complete (S24: YES), it determines whether the control mode is the first mode (S25). When the CPU 31 determines that the mode flag value is 0 and the control mode is the first mode (S25: YES), it resumes the power supply to the replacement motors (sub-magazine motor 53, arm motor 54) that had been suspended (S26). When the power supply to the replacement motors is resumed, the holding brakes 532, 542 are released, allowing the sub-magazine 41A to rotate. The CPU 31 then proceeds to S31.

[0070] If the CPU 31 determines that the value of the mode flag is 1 and that the mode is not the first mode (S25: NO), the CPU 31 proceeds to S31. In this case, the mode is the second mode, power is constantly supplied to the tool change motor, 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 change command is indexed to position Q. The CPU 31 drives the arm motor 54 to move the arm 44A in direction A, and drives the air cylinder 461 to use the holder 46A to change the tool 3 into the tool magazine 21 of the tool changer 4A (S32).

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

[0073] When the CPU 31 determines that the arm 44A is located at the initial position and that the tool 3 has been replaced (S33: YES), it drives the air cylinder 611 to start closing the opening 64A with the shutter 61A (S34). The CPU 31 then determines whether or not the closing of the opening 64A has been completed (S35). In the determination of S35, if 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 has been completed. When the CPU 31 determines that the closing of the opening 64A has not been completed (S35: NO), the process returns to S34.

[0074] When the CPU 31 determines that the closing of the opening 64A is complete (S35: YES), it determines whether the control mode is the first mode (S36). When the CPU 31 determines that the mode flag value is 0 and the control mode is the first mode (S36: YES), it interrupts the power supply to the tool change motor, which had been resumed (S37). When the power supply to the tool change motor is interrupted, the holding brakes 532 and 542 are activated, and the state of the tool change device 4A is maintained by the holding brakes 532 and 542. The CPU 31 then proceeds to S38.

[0075] If the CPU 31 determines that the value of the mode flag is 1 and that the mode is not the first mode (S36: NO), the process proceeds to S38. In this case, the control mode is the second mode, power is constantly supplied to the tool changer motor, and the tool changer motor maintains the state of the tool changer 4A.

[0076] The CPU 31 lowers the spindle 9 located at the ATC origin (S38), and proceeds to S13 (see FIG. 9).

[0077] 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 S 13. The various processes executed in S16 include, for example, a positioning process for the spindle 9, a rotation process for the spindle 9, and a tool change process for changing the tool 3 attached to the spindle 9.

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

[0079] <Operations and Effects of the Present Embodiment> As described above, the numerical controller 30 interrupts the power supply to the tool changer motor when the tool changer 4A is in a standby state and not in operation (S6, S37). When the numerical controller 30 outputs a tool change command while the power supply to the tool changer motor is interrupted (S16), the numerical controller 30 resumes the power supply to the tool changer motor (S26). When the tool changer 4A is in a standby state and not in operation, the numerical controller 30 interrupts the power supply to the tool changer motor, which is a servo motor. When the numerical controller 30 outputs a tool change command, the numerical controller 30 resumes the power supply to the tool changer motor, which was previously interrupted, and performs tool 3 change between the tool changer 4A and the tool magazine 21. Therefore, the numerical controller 30 can reduce the power consumption of the tool changer motor that drives the tool changer 4A.

[0080] The numerical control device 30 determines whether the tool 3 has been completely replaced in the tool magazine 21 of the tool changer 4A (S33). If the numerical control device 30 determines that the tool 3 has been completely replaced, it interrupts the power supply to the replacement motor, which had been resumed (S37). When the numerical control device 30 completes the replacement of the tool 3 between the tool changer 4A and the tool magazine 21, the power supply to the replacement motor is interrupted again. Thus, the numerical control device 30 can reduce the power consumption of the replacement motor that drives the tool changer 4A.

[0081] The tool changer 4A has a sub-magazine 41A and an arm 44A. The changer motor is a servo motor and includes a sub-magazine motor 53 and an arm motor 54. The sub-magazine 41A is rotated by the drive of the sub-magazine motor 53 until the tool 3 to be changed is located at position Q. The arm 44A is moved linearly in direction A by the drive of the arm motor 54. The numerical control device 30 controls the interruption or resumption of power supply to both the sub-magazine motor 53, which drives the sub-magazine 41A to rotate the tool 3 to position Q, and the arm motor 54, which drives the arm 44A to change the tool 3. Thus, the numerical control device 30 can reduce the power consumption of the changer motor that drives the tool changer 4A.

[0082] The front wall 63A of the tool changer cover 60A separates the tool magazine 21 from the tool changer 4A. The shutter 61A opens and closes an opening 64A in 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 whether the opening 64A is open. The numerical controller 30 determines that the opening of the opening 64A is complete when the sensor 612 detects that the cover 62A is open (S24). When the opening of the opening 64A is complete, the numerical controller 30 resumes the power supply to the tool changer motor (S26). In the numerical controller 30, the opening 64A is opened by the shutter 61A, and the tool 3 begins to be changed into the tool magazine 21 of the tool changer 4A. In the numerical controller 30, when the sensor 612 detects that the cover 62A is open, the power supply to the tool changer motor is resumed. Therefore, the numerical control device 30 can easily control the timing for restarting the power supply to the replacement motor.

[0083] The numerical controller 30 determines that the closure of the opening 64A is complete when the sensor 612 detects that the cover 62A is not open (S35). When the opening of the opening 64A is complete, the numerical controller 30 interrupts the power supply to the tool change motor (S37). In the numerical controller 30, when the tool 3 is completely replaced in the tool magazine 21 of the tool change device 4A, the shutter 61A closes the opening 64A. In the numerical controller 30, when the sensor 612 detects that the cover 62A is not open, the power supply to the tool change motor is interrupted. Therefore, the numerical controller 30 can easily control the timing of interrupting the power supply to the tool change 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 always performed. This allows the numerical control device 30 to achieve specifications that match the machine tool 1.

[0085] <Modifications> The present invention can be modified in various ways from the above-described embodiment. The various modifications described below can be combined with each other as long as no contradictions arise. The numerical control device 30 does not necessarily have to be provided on the machine tool 1, but may also 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), or the like may be used to control the numerical control device 30. The main processing may be distributed among 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. Non-transitory storage media do not necessarily include temporary 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 the network and stored in the storage device 34. In this case, the control program may be stored in a non-transitory storage medium such as an HDD provided in the server.

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

[0089] The tool magazine 21 may be driven by a servo motor to transport the tools 3 to be attached to the spindle 9 to the tool changing position. In the above embodiment, the tool magazine 21 is of a turret type, but the tool magazine 21 may be of an arm type, for example. The tool magazine 21 is rotated by the drive of the magazine motor 52, but may also be translated by the drive of the magazine motor 52, for example. 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 also be provided in the machine tool 1.

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

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

[0092] The configuration of the sub-magazine 41A of the tool changer 4A may be changed as appropriate. While the sub-magazine 41A is a turret type, the sub-magazine 41A may be, for example, an arm type. In the above embodiment, the sub-magazine 41A rotates when driven by the sub-magazine motor 53, but it may also move in a translational manner when driven by the sub-magazine motor 53, for example. The sub-magazine 41A may move in a translational manner in combination with a rotational movement. The number of sub-magazine motors 53 that operate the sub-magazine 41A may not be one, but multiple.

[0093] The configuration of the arm 44A of the tool changer 4A may be modified as appropriate. In the above embodiment, the arm 44A moves translationally in direction A by driving the arm motor 54. However, the arm 44A may also rotate by driving the arm motor 54. The arm 44A that rotates by driving the arm motor 54 may be, for example, a vertically articulated robot arm or a horizontally articulated robot arm. In this case, the number of arm motors 54 is multiple. The arm 44A may move translationally and rotationally in combination. The holder 46A holds the tool 3 by driving the air cylinder 461, but may also hold the tool by driving a servo motor, for example. In this case, the numerical control device 30 may interrupt or resume the power supply to the servo motor that operates the holder 46A at the same timing as the tool changing motor.

[0094] The numerical control device 30 does not need to interrupt the power supply to the tool change motor when the tool change device 4A has completed changing the tool 3 in the tool magazine 21. In the above embodiment, the numerical control device 30 determined that the tool change is complete when the arm 44A is located at the initial position based on the encoder 541. However, the numerical control device 30 may determine that the rotation of the tool magazine 21 is complete when a predetermined time has elapsed since the arm motor 54 was driven.

[0095] The machine tool 1 does not need to have the tool changer cover 60A. The opening 64A may be provided in the wall of the tool changer cover 60A that separates the tool magazine 21 and the tool changer 4A, and is not limited to being provided in the front wall 63A. Instead of the air cylinder 611, for example, a stepping motor may be used to move the shutter 61A or the cover 62A between the open state and the closed state.

[0096] Instead of the magnetic sensor 612, a photoelectric sensor or a microswitch, for example, may be used to detect whether the cover 62A is in the open state or not. In the above embodiment, the sensor 612 detects whether the cover 62A is in the open state or not. However, the sensor 612 may also detect whether the cover 62A is in the closed state or not. In this case, in the determination at S24 of the main processing, the CPU 31 may determine that the opening 64A is open if the sensor 612 detects that the cover 62A is not in the closed state. In the determination at S35 of the main processing, the CPU 31 may determine that the opening 64A is closed if the sensor 612 detects that the cover 62A is in the closed state.

[0097] The numerical control device 30 may resume the power supply to the changing motor when the tool change command is output, or may interrupt the power supply to the changing motor when the tool 3 has been changed into the tool magazine 21 of the tool changer 4A.

[0098] In the above embodiment, when the control command interpreted during execution of the NC program is a tool change command, the numerical control device 30 outputs the tool change command and changes the tool 3 to the tool magazine 21 of the tool changer 4A. However, when the NC program is not being executed, the operator may input an instruction to change the tool 3 using the operation unit 16, and the numerical control device 30 may change the tool 3 if the instruction is accepted by the numerical control device 30.

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

[0100] REFERENCE SIGNS LIST 1 Machine tool 4, 4A, 4B Tool changer 20 Tool changer 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, the numerical control device comprising: an interrupting 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 restarting unit that restarts power supply to the servo motor when the output unit outputs the tool change command in a state where the power supply to the servo motor is interrupted by the interrupting unit. The numerical control device is characterized by comprising the above components.

2. The numerical control device according to claim 1, further comprising a determination unit that determines whether or not the replacement of the tool based on the tool change command is completed, wherein the interrupting unit interrupts power supply to the servo motor when the determination unit determines that the replacement of the tool is completed in a state where the power supply to the servo motor is restarted by the restarting unit.

3. The tool changer has 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 moving between the sub-magazine and the tool magazine. The servo motor has a first servo motor for driving the sub-magazine and a second servo motor for driving the arm. The numerical control device according to claim 2 is characterized by comprising the above components.

4. The machine tool further includes 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 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 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 restarts 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. The numerical control device according to claim 3, characterized in that.

5. The machine tool further includes 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 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 it is determined by the determination unit that the tool change 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 interrupts 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 while the power supply to the servo motor is restarted by the restart unit. 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 tools to be mounted on a spindle and a tool changer capable of changing the tools with respect to the tool magazine by driving a servo motor, the control method comprising: an interruption step of interrupting power supply to the servo motor in a standby state where the tool changer is not operated; an output step of outputting a tool change command for changing the tool loaded in the tool magazine to the tool changer; and a restart step of restarting power supply to the servo motor when the output step outputs the tool change command in a state where power supply to the servo motor is interrupted by the interruption step.

8. A program for causing a computer that controls the operation of a machine tool including a tool magazine capable of loading tools to be mounted on a spindle and a tool changer capable of changing the tools 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 changing the tool loaded in the tool magazine to the tool changer; and a restart process of restarting power supply to the servo motor when the output process outputs the tool change command in a state where power supply to the servo motor is interrupted by the interruption process.

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