Numerical control device, control method, and program

Abstract

Provided are a numerical control device, a control method, and a program that can reduce the electrical power consumption of a servo motor that drives a tool magazine.　The numerical control device detects the position of a main shaft in the Z-axis direction by an encoder of a Z-axis motor. The numerical control device interrupts the supply of electrical power to a magazine motor in a standby state in which the tool magazine is not operated. When the numerical control device outputs a tool replacement command, the main shaft moves from a processing area to a tool replacement area. The numerical control device resumes the supply of electrical power to the magazine motor on condition that it is detected that the main shaft is positioned in the tool replacement area when replacing a tool attached to the main shaft on the basis of the tool replacement command.

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 stops operating the electromagnetic brake.

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

[0004] When a tool change command is output, the spindle moves from the machining area where the workpiece is machined to the tool change area to change the tool between the tool magazine and the spindle. The tool change device resumes power supply to the servo motor when the tool change command is output, so power is consumed in the servo motor while the spindle moves from the machining area to the tool change area.

[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 magazine.

[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 having a spindle that can be fitted with a tool and that can move between a machining area where a workpiece is machined using the tool and a tool change area where the tool is changed, and a tool magazine that can load the tool and that transports the tool fitted to the spindle to a tool change position by driving a servo motor, and is characterized in that it comprises: an interruption unit that interrupts the supply of power to the servo motor in a standby state in which the tool magazine is not in operation; a position detection unit that detects the position of the spindle; and a resumption unit that resumes the supply of power to the servo motor that was interrupted by the interruption unit, on condition that the position detection unit detects that the spindle is located within the tool change area.

[0007] When the numerical control device of the first aspect outputs a tool change command, the spindle moves from the machining area to the tool change area, and the servo motor drives the tool magazine. The numerical control device resumes power supply to the servo motor when it detects that the spindle is located within the tool change area. Therefore, the numerical control device can reduce the power consumption of the servo motor compared to when power supply to the servo motor is resumed when the tool change command is output.

[0008] In the numerical control device, the tool magazine may be operable when the spindle is located at a specific spindle position within the tool changing area, and the restart unit may resume power supply to the servo motor on the condition that the position detection unit detects that the spindle is located at the specific spindle position. In the numerical control device, when the spindle reaches the specific spindle position in the tool changing area at which the tool magazine is to operate, the tool magazine is operated by driving the servo motor. Since power supply to the servo motor is resumed immediately before the tool magazine begins to operate, the numerical control device can further reduce the power consumption of the servo motor.

[0009] In the numerical control device, the interruption unit may interrupt the power supply to the servo motor on the condition that the operation of the tool magazine by the servo motor is completed while the power supply to the servo motor has been resumed by the resumption unit. In the numerical control device, the tool magazine is driven by the servo motor to transport tools to be attached to the spindle to a tool change position. In the numerical control device, the power supply to the servo motor is interrupted when it is determined that the operation of the tool magazine has been completed. Therefore, the numerical control device can reduce the power consumption of the servo motor compared to when power is supplied to the servo motor from the time the operation of the tool magazine is completed until the spindle moves to the machining area.

[0010] In the numerical control device, the interruption unit may interrupt the power supply to the servo motor on the condition that the operation of the tool magazine by the servo motor is completed with the resumption unit resuming the power supply to the servo motor and the position detection unit detects that the spindle is located within the tool change area. In the numerical control device, the operation of the tool magazine by the servo motor is completed and the spindle moves from the tool change area to the machining area. In the numerical control device, the power supply to the servo motor is interrupted on the condition that the spindle is detected to be located within the tool change area. Thus, the numerical control device can interrupt the power supply to the servo motor at a position within the tool change area according to specifications, and the power consumption of the servo motor can be reduced compared to when power is supplied to the servo motor from the time the operation of the tool magazine is completed until the spindle moves to the machining area.

[0011] In the numerical control device, the tool magazine may be operable when the spindle is located at a specific spindle position within the tool changing area, and the restarting unit may resume power supply to the servo motor on the condition that the position detecting unit detects that the tool magazine is operable and that the spindle is located at a specific spindle position within the tool changing area, and the interrupting unit may interrupt power supply to the servo motor when the operation of the tool magazine by the servo motor is completed with the restarting unit resuming power supply to the servo motor and the position detecting unit detects that the spindle has moved away from the specific spindle position. In the numerical control device, power is supplied to the servo motor while the servo motor is driving, and power supply to the servo motor is interrupted when driving of the servo motor is completed. Thus, the numerical control device can further reduce power consumption in 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 spindle capable of mounting a tool and movable between a machining area where a workpiece is machined using the tool and a tool change area where the tool is changed, and a tool magazine capable of loading the tool and driving a servo motor to transport the tool mounted on the spindle to a tool change position, the control method being characterized in that, in a standby state in which the tool magazine is not in operation, the control method includes an interruption step of interrupting the supply of power to the servo motor, a position detection step of detecting the position of the spindle, and a resumption step of resuming the supply of power to the servo motor that was interrupted by the interruption step, on condition that the position detection step has detected that the spindle is located within the tool change area.

[0014] A program according to a third aspect of the present invention is characterized in that it causes a computer that controls the operation of a machine tool including a spindle that can be fitted with a tool and that can move between a machining area where a workpiece is machined using the tool and a tool change area where the tool is changed, and a tool magazine that can load the tool and that is driven by a servo motor to transport the tool fitted to the spindle to a tool change position, to execute, in a standby state in which the tool magazine is not in operation, an interruption process that interrupts the supply of power to the servo motor, a position detection process that detects the position of the spindle, and a resume process that resumes the supply of power to the servo motor that was interrupted by the interruption process, on condition that the position detection process has detected that the spindle is located within the tool change area.

[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] Fig. 1 is a perspective view showing the machine tool 1. Fig. 2 is a longitudinal sectional view of the spindle head 7 and its periphery. Fig. 3 is a block diagram showing the electrical configuration of the numerical control device 30 and the machine tool 1. Fig. 4 is a diagram showing control of power supply to the magazine motor 55 in each of the first mode and the second mode. Fig. 5 is a flowchart showing main processing. Fig. 6 is a flowchart showing the main processing, and is a continuation of Fig. 5. Fig. 7 is a diagram showing the position of the spindle 9 in the Z-axis direction.

[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 on the upper surface of a table 13. A numerical control device 30 (see Figure 2) 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, a column 5, a table device 10, a Z-axis movement mechanism 8, a spindle head 7, a spindle 9, a tool changer 20, a control box 6, and an operation panel 15 (see Figure 3). The base 2 is a metal base that is approximately rectangular and long in the front-to-rear direction. The column 5 is fixed to the rear part of the top surface of the base 2. The column 5 is an upright pillar that extends in the vertical direction. The control box 6 is fixed to the back surface of the column 5. The control box 6 houses a numerical control device 30.

[0020] 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. 3 ). The operation unit 16 receives 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.

[0021] The table device 10 has a Y-axis movement mechanism (not shown), a Y-axis table 12, a table 13, and an X-axis movement mechanism (not shown). The Y-axis movement mechanism is provided on the upper surface of the base 2 and in front of the column 5, and has a Y-axis motor 52 (see FIG. 3). The Y-axis movement mechanism moves the Y-axis table 12 in the Y-axis direction in response to driving of the Y-axis motor 52. The X-axis movement mechanism is provided above the Y-axis table 12, and has an X-axis motor 51 (see FIG. 3). The X-axis movement mechanism moves the table 13 in the X-axis direction in response to driving of the X-axis motor 51. Therefore, the table 13 can be moved in the X-axis and Y-axis directions above the base 2 by the X-axis movement mechanism and the Y-axis movement mechanism.

[0022] The table device 10 has a Y-axis movement mechanism (not shown), a Y-axis table 12, an X-axis movement mechanism (not shown), and a table 13. The Y-axis movement mechanism is provided on the front upper surface of the base 2 and includes a Y-axis rail, a Y-axis ball screw, and a Y-axis motor 52 (see FIG. 3). The Y-axis rail and the Y-axis ball screw extend in the Y-axis direction. The Y-axis rail guides the Y-axis table 12 in the Y-axis direction. The Y-axis table 12 is a rectangular plate in a plan view and has a Y-axis nut (not shown) attached to its underside. The Y-axis nut is threaded onto the Y-axis ball screw. When the Y-axis motor 52 rotates the Y-axis ball screw, the Y-axis table 12 moves in the Y-axis direction, guided by the Y-axis rail together with the Y-axis nut.

[0023] The X-axis movement mechanism is provided on the upper surface of the Y-axis table 12 and includes an X-axis rail, an X-axis ball screw, and an X-axis motor 51 (see FIG. 3). The X-axis rail and the X-axis ball screw extend in the X-axis direction. The X-axis rail guides the table 13 in the X-axis direction. The table 13 is provided on the upper surface of the Y-axis table 12 and is a rectangular plate in plan view. A workpiece (not shown) is held on the upper surface of the table 13. An X-axis nut (not shown) is provided on the lower surface of the table 13. The X-axis nut is threaded onto the X-axis ball screw. When the X-axis motor 51 rotates the X-axis ball screw, the table 13, together with the X-axis nut, is guided by the X-axis rail and moves in the X-axis direction. Therefore, the table 13 can be moved in the X-axis and Y-axis directions above the base 2 by the X-axis movement mechanism and the Y-axis movement mechanism.

[0024] <Structure of Z-axis movement mechanism 8> As shown in Figure 2, the Z-axis movement mechanism 8 is provided in the front part of the column 5. The Z-axis movement mechanism 8 has a Z-axis rail (not shown), a Z-axis ball screw 81, bearings 82 and 83, a cam follower 89, and a Z-axis motor 53 (see Figure 3). The Z-axis rail and Z-axis ball screw 81 are provided in the front part of the column 5 and extend in the Z-axis direction. The bearings 82 and 83 are inserted into the Z-axis ball screw 81 and rotatably support the Z-axis ball screw 81. The bearing 82 is provided above the bearing 83. The cam follower 89 is provided at the front end of the bearing 82. The cam follower 89 slides on the cam surface of a plate cam 74, which will be described later.

[0025] The Z-axis motor 53 is fixed above the bearing portion 82. The Z-axis ball screw 81 is connected to the output shaft of the Z-axis motor 53 via a coupling (not shown). A Z-axis nut 84 is threadedly engaged with the Z-axis ball screw 81 between the bearing portions 82 and 83. The Z-axis nut 84 is fixed to the spindle head 7, which will be described later. When the Z-axis motor 53 rotates the Z-axis ball screw 81, the spindle head 7, together with the Z-axis nut 84, is guided by the Z-axis rail and moves in the Z-axis direction.

[0026] <Internal structure of spindle head 7> As shown in Figure 2, the spindle head 7 is box-shaped and provided at the front of the column 5. The spindle head 7 has a spindle motor 54, a support shaft 71, a crank lever 72, and a spring 73. The spindle motor 54 is fixed to the front of the top surface of the spindle head 7.

[0027] The support shaft 71 extends left and right inside the rear part of the spindle head 7. The crank lever 72 is generally L-shaped when viewed from the left side, and its bent portion engages with the support shaft 71. The crank lever 72 can swing around the support shaft 71. A plate cam 74 is provided at the rear end of the crank lever 72. A cam surface that can come into contact with and separate from the cam follower 49 is formed on the back surface of the plate cam 74. The spring 73 is a compression coil spring that extends forward and backward. One end of the spring 73 is fixed to the back wall of the spindle head 7. The other end of the spring 73 is fixed to the rear end of the crank lever 72 below the plate cam 74. The spring 73 constantly urges the crank lever 72 clockwise when viewed from the right side.

[0028] <Structure of Spindle 9> As shown in Figure 2, the spindle 9 is provided inside the front part of the spindle head 7 and extends in the vertical direction. The spindle 9 is rotatably supported by the spindle head 7. The spindle 9 is connected to the output shaft of the spindle motor 54. The spindle 9 has a shaft hole 91, an attachment hole 92, a clamping portion 93, and a drawbar 94.

[0029] A shaft hole 91 is provided at the upper end of the spindle 9. A mounting hole 92 is provided at the lower end of the spindle 9 and communicates with the shaft hole 91. A clamping portion 93 is provided at the lower end inside the shaft hole 91. The clamping portion 93 is capable of clamping the tool 3. A draw bar 94 is provided at the upper end of the clamping portion 93 inside the shaft hole 91. A pin 95 is provided at the upper end of the draw bar 94 and protrudes outside the spindle 9 through a through hole (not shown) that penetrates the spindle 9 in the front-rear direction. The pin 95 is located below the front end of the crank lever 72. When the crank lever 72 swings, the front end of the crank lever 72 moves toward and away from the pin 95.

[0030] 2, the tool changer 20 includes a tool magazine 21 and a magazine motor 55. The tool magazine 21 is a turret type. The tool magazine 21 includes a support base 24, a support shaft 25, a magazine body 22, a plurality of grip arms 23, and a reducer 26.

[0031] The support base 24 is fixed to a frame (not shown). The frame is fixed to the column 5 and is provided near the spindle head 7. The support base 24 is located in front of the spindle head 7 and rotatably supports a support shaft 25. The support shaft 25 extends diagonally downward relative to the front of the machine tool 1. The magazine body 22 is provided at the front of the support base 24 and is supported by the support shaft 25. The magazine body 22 is disk-shaped and is provided with its front surface facing the front of the machine tool 1.

[0032] 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 tip of the grip arm 23 detachably grips a tool 3. In other words, the tool magazine 21 loads tools 3 using the plurality of grip arms 23. The reducer 26 is provided on the upper part of the support base 24. The reducer 26 has a plurality of gears and cams (not shown). The magazine motor 55 is provided on the upper part of the reducer 26. The rotating shaft of the magazine motor 55 is connected to the reducer 26. When the magazine motor 55 is driven, the magazine body 22 rotates via the reducer 26.

[0033] <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 3. The numerical control device 30 has a CPU 31, ROM 32, RAM 33, a storage device 34, an input / output unit 35, and drive circuits 41 to 45. The CPU 31 controls the numerical control device 30 in an integrated manner.

[0034] 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 (described later), a control program for executing the main processing (see FIG. 5), and the like. The NC program is a machining program made up of a plurality of lines. Each line of the NC program includes control commands for performing various operations, including axis movement and tool change of the machine tool 1. 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.

[0035] 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 41 to 45 , operation unit 16 , and display unit 17 .

[0036] The drive circuit 41 is connected to the input / output unit 35, the X-axis motor 51, and the encoder 51A. The drive circuit 42 is connected to the input / output unit 35, the Y-axis motor 52, and the encoder 52A. The drive circuit 43 is connected to the input / output unit 35, the Z-axis motor 53, and the encoder 53A. The drive circuit 44 is connected to the input / output unit 35, the spindle motor 54, and the encoder 54A. The drive circuit 45 is connected to the input / output unit 35, the magazine motor 55, and the encoder 55A.

[0037] Based on commands input from CPU 31, drive circuits 41, 42, 43, 44, and 45 output drive currents to X-axis motor 51, Y-axis motor 52, Z-axis motor 53, spindle motor 54, and magazine motor 55. The X-axis motor 51, Y-axis motor 52, Z-axis motor 53, spindle motor 54, and magazine motor 55 are all servo motors, and rotate in response to the input drive current.

[0038] The encoders 51A, 52A, 53A, 54A, and 55A are all absolute encoders, and detect the rotational positions of the X-axis motor 51, the Y-axis motor 52, the Z-axis motor 53, the main shaft motor 54, and the magazine motor 55.

[0039] Encoders 51A, 52A, 53A, 54A, and 55A output feedback signals indicating the detected rotational positions to drive circuits 41, 42, 43, 44, and 45. Based on the feedback signals, drive circuits 41, 42, 43, 44, and 45 perform feedback control on X-axis motor 51, Y-axis motor 52, Z-axis motor 53, spindle motor 54, and magazine motor 55. CPU 31 detects the position of table 13 in the X-axis direction, the position of table 13 in the Y-axis direction, the position of spindle 9 in the Z-axis direction, and the rotational position of tool magazine 21, based on the feedback signals output by encoders 51A, 52A, 53A, and 55A.

[0040] The magazine motor 55 has a holding brake 55B. The holding brake 55B is a non-excitation operation type brake that operates without consuming power. The holding brake 55B holds the rotating shaft of the magazine motor 55 when power is not supplied to the magazine motor 55, thereby maintaining the state of the tool magazine 21 (the rotational position of the tool magazine 21). When power is supplied to the magazine motor 55, the holding brake 55B releases the holding of the rotating shaft of the magazine motor 55, allowing the tool magazine 21 to be rotated by the magazine motor 55. When power is supplied to the magazine motor 55, the magazine motor 55 is driven based on a command that determines the rotational position of the tool magazine 21, thereby maintaining the state of the tool magazine 21.

[0041] <Replacing the tool 3 by the tool changer 20> The replacement of the tool 3 by the tool changer 20 will be described with reference to Figures 2 and 7. When the tool changer 20 is to replace the tool 3, the numerical control device 30 outputs a tool change command. When the numerical control device 30 outputs the tool change command, the spindle 9 is raised from the machining area shown in Figure 7 by driving the Z-axis motor 53. The machining area is an area for machining a workpiece, and is an area on the table 13 side (below) with respect to the machine origin of the Z axis. Hereinafter, the machine origin of the Z axis will be referred to as the Z-axis origin.

[0042] The spindle 9 rises and reaches the tool change area shown in FIG. 7 . The tool change area is an area for changing the tool 3 attached to the spindle 9, and is located above the machine origin of the Z axis. When the spindle 9 reaches the tool change area, the cam follower 89 slides on the cam surface of the plate cam 74. The crank lever 72 rotates counterclockwise around the support shaft 71 as viewed from the right side, and the front end of the crank lever 72 engages with the pin 95 from above, pressing the draw bar 94 downward. The draw bar 94 urges the clamping portion 93 downward, and the clamping portion 93 releases the clamping of the tool 3. At the same time, the grip arm 23, located at the tool change position, grips the tool 3. The tool change position is the lowest position of the magazine body 22, facing closely to the spindle 9.

[0043] The spindle 9 rises from the Z-axis origin to the ATC origin shown in Figure 7. The ATC origin is the position of the spindle 9 at which the tool magazine 21 becomes rotatable and is also the position of the spindle 9 within the tool changing area. The tool 3 is detached from the attachment hole 92 of the spindle 9 while still held by the grip arm 23. The tool 3 detached from the spindle 9 is referred to as the first tool.

[0044] When the spindle 9 reaches the ATC origin, the magazine motor 55 is driven based on a control command from the numerical control device 30, causing the magazine body 22 of the tool magazine 21 to rotate. The tool changer 20 indexes the tool 3 (hereinafter referred to as the second tool) specified by the tool change command to the tool change position. At this time, the magazine body 22 rotates from a state in which the first tool is in the tool change position to a state in which the second tool is in the tool change position. The second tool indexed to the tool change position is positioned below the spindle 9, which has moved to the ATC origin.

[0045] The spindle 9 is lowered from the ATC origin by the rotation of the Z-axis motor 53. The second tool enters the mounting hole 92 of the spindle 9. The cam follower 89 slides on the cam surface of the plate cam 74. The crank lever 72 rotates clockwise around the support shaft 71 when viewed from the right side, and the front end of the crank lever 72 moves away from the pin 95, releasing the downward pressure on the draw bar 94. The draw bar 94 releases the downward bias of the clamping portion 93, and the clamping portion 93 clamps the tool 3. The second tool is detached from the grip arm 23, which is in the tool change position. The tool 3 is mounted in the mounting hole 92 of the spindle 9. The spindle 9 moves from the tool change area to the Z-axis origin, which is the top end of the machining area, and the change of the tool 3 is completed.

[0046] <Control Mode of Power Supply to Magazine Motor 55> Referring to FIG. 4 , the control mode of power supply to the magazine motor 55 will be described. The numerical control device 30 switches between a first mode and a second mode as a control mode of power supply to the magazine motor 55. In the first mode, power is supplied to the magazine motor 55 when the tool magazine 21 is rotated as part of the tool magazine 21 operation, and power is not supplied to the magazine motor 55 when the tool magazine 21 is in a standby state where the tool magazine 21 is not being rotated. In the second mode, power is supplied to the magazine motor 55 regardless of the state of the tool magazine 21. Here, "power supply to the magazine motor 55" refers to power supply to a power terminal for receiving a drive current input to rotate the magazine motor 55. In other words, it is sufficient that power supply to the power terminal of the magazine motor 55 is controlled; power may or may not be supplied to a signal terminal for transmitting and receiving signals for controlling the magazine motor 55.

[0047] More specifically, in the first mode, when the tool 3 attached to the spindle 9 is not changed, power is not supplied to the magazine motor 55, and the holding brake 55B maintains the state of the tool magazine 21. When the tool 3 attached to the spindle 9 is not changed, it is, for example, when a workpiece is machined using the tool 3.

[0048] In the first mode, power is supplied to the magazine motor 55 on the condition that it is detected that the spindle 9 is located within the tool change area. In this embodiment, when it is detected that the spindle 9 is located at the ATC origin within the tool change area, power is supplied to the magazine motor 55. When the numerical control device 30 outputs a tool change command at time T1 to change the tool 3, the spindle 9 located in the machining area rises toward the ATC origin within the tool change area.

[0049] When the spindle 9 reaches the ATC origin at time T3 (>T1), the holding brake 55B is released to rotate the tool magazine 21, and power supply to the magazine motor 55 is resumed. Whether the spindle 9 has reached the ATC origin is determined based on the position of the spindle 9 in the Z-axis direction detected by the encoder 53A.

[0050] The tool magazine 21 is rotated by driving the magazine motor 55. When the tool 3 attached to the spindle 9 is indexed to the tool change position at time T4 (>T3), the spindle 9 starts to descend from the ATC origin. Whether the tool 3 attached to the spindle 9 has been indexed to the tool change position is determined based on the rotational position of the tool magazine 21 detected by the encoder 55A.

[0051] In the first mode, the power supply to the magazine motor 55 is interrupted on the condition that the rotation of the tool magazine 21 is completed. In this embodiment, the power supply to the magazine motor 55 is interrupted on the condition that the spindle 9 is detected to be located at a predetermined position within the tool change area. Here, "on the condition that the spindle 9 is detected to be located within the tool change area" means that the spindle 9 is detected to have moved away from the predetermined position within the tool change area. In this embodiment, the predetermined position within the tool change area of ​​the spindle 9 is the ATC origin. When the spindle 9 starts to move down and moves away from the ATC origin, the power supply to the magazine motor 55 is interrupted and the holding brake 55B is activated. Whether the spindle 9 has moved away from the ATC origin is determined based on the position of the spindle 9 in the Z-axis direction detected by the encoder 53A.

[0052] Since no power is consumed when the holding brake 55B is activated, power is consumed by the magazine motor 55 in the first mode from time T3 to time T4. Then, no power is supplied to the magazine motor 55 until the tool magazine 21 rotates next based on a tool change command, and the state of the tool magazine 21 is maintained by the holding brake 55B.

[0053] On the other hand, in the second mode, power is supplied to the magazine motor 55 regardless of the state of the tool magazine 21, so the state of the tool magazine 21 is maintained by the magazine motor 55, which is driven based on a feedback signal from the encoder 55A. For example, an unbalanced load generated in the tool magazine 21 due to the loading of tools 3 may cause the tool magazine 21 to rotate from a designated rotation position. In this case, the drive circuit 45 drives the magazine motor 55 based on the feedback signal to reversely rotate the tool magazine 21 so that the tool magazine 21 returns to the designated rotation position. In this way, in the second mode, the magazine motor 55 is driven to maintain the state of the tool magazine 21, so power is constantly consumed by the magazine motor 55.

[0054] 5 and 6, 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.

[0055] 5, when the main processing starts, CPU 31 determines whether or not power is being supplied to X-axis motor 51, Y-axis motor 52, Z-axis motor 53, spindle motor 54, and magazine motor 55 (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 X-axis motor 51, Y-axis motor 52, Z-axis motor 53, spindle motor 54, and magazine motor 55 when machine tool 1 is powered on. If CPU 31 determines that power is not being supplied to X-axis motor 51, Y-axis motor 52, Z-axis motor 53, spindle motor 54, and magazine motor 55 (S1: NO), the processing returns to S1.

[0056] When the CPU 31 determines that power is being supplied to the X-axis motor 51, the Y-axis motor 52, the Z-axis motor 53, the spindle motor 54, and the magazine motor 55 (S1: YES), it determines whether a mode switching instruction has been received (S2). The mode switching instruction is an instruction to switch the control mode from the first mode to the second mode, or to switch the control mode from the second mode to the first mode. The operator inputs the mode switching instruction using the operation unit 16 of the operation panel 15.

[0057] When the CPU 31 determines that a mode switching instruction has been received (S2: YES), it determines whether the control mode is the first mode (S3). When the CPU 31 determines that the control mode is the first mode (S3: YES), it switches the control mode from the first mode to the second mode, resumes power supply to the magazine motor 55 (S4), and releases the operation of the holding brake 55B. 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 control mode is the first mode. When the value of the mode flag is 1, it indicates that the control mode is the second mode.

[0058] If the CPU 31 determines that the control mode is not the first mode (S3: NO), it switches the control mode from the second mode to the first mode, interrupts the power supply to the magazine motor 55 (S6), and activates the holding brake 55B. The holding brake 55B maintains 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.

[0059] 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.

[0060] When the CPU 31 determines that a machining start command has been received (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 brake 55B holds the state of the tool magazine 21, and if the control mode is the second mode, the magazine motor 55 holds the state of the tool magazine 21. The spindle 9 is located in the machining area.

[0061] 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 ends the 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 proceeds to S21 (see FIG. 6).

[0062] 6, in order to change the tool 3 attached to the spindle 9, the CPU 31 drives the Z-axis motor 53 to start raising the spindle 9 (S21). The spindle 9 rises from the machining area toward the ATC origin in the tool changing area. The tool 3 attached to the spindle 9 is detached from the spindle 9 and gripped by the grip arm 23 of the tool magazine 21.

[0063] The CPU 31 determines whether the spindle 9 is located at the ATC origin as a condition for detecting that the spindle 9 is located within the tool change area (S22). The CPU 31 makes the determination in S22 based on the rotational position of the Z-axis motor 53 identified by the encoder 53A. If the CPU 31 determines that the spindle 9 is not located at the ATC origin (S22: NO), the process returns to S22. If the CPU 31 determines that the spindle 9 is located at the ATC origin (S22: YES), the CPU 31 stops driving the Z-axis motor 53 and stops the lifting of the spindle 9 (S23).

[0064] The CPU 31 determines whether the control mode is the first mode (S24). If the CPU 31 determines that the mode flag value is 0 and the control mode is the first mode (S24: YES), it resumes the power supply to the magazine motor 55, which had been suspended (S25). When the power supply to the magazine motor 55 is resumed, the holding brake 55B is released, allowing the tool magazine 21 to rotate. The CPU 31 then proceeds to S31.

[0065] If the CPU 31 determines that the value of the mode flag is 1 and that the control mode is not the first mode (S24: NO), the CPU 31 proceeds to S31. In this case, the control mode is the second mode, power is constantly supplied to the magazine motor 55, and the tool magazine 21 can rotate.

[0066] The CPU 31 drives the magazine motor 55 to rotate the magazine body 22 of the tool magazine 21 (S31). The CPU 31 rotates the tool magazine 21 so that the tool 3 to be attached to the spindle 9 is indexed to the tool change position.

[0067] The CPU 31 determines whether the tool 3 attached to the spindle 9 has been indexed to the tool change position (S32) as a condition for the completion of rotation of the tool magazine 21 by the magazine motor 55. The CPU 31 makes the determination in S32 based on the rotation position of the magazine motor 55 identified by the encoder 55A. If the CPU 31 determines that the tool 3 attached to the spindle 9 has not been indexed to the tool change position (S32: NO), the CPU 31 returns the process to S32. If the CPU 31 determines that the tool 3 attached to the spindle 9 has been indexed to the tool change position (S32: YES), the CPU 31 stops driving the magazine motor 55 and stops rotation of the tool magazine 21 (S33).

[0068] The CPU 31 drives the Z-axis motor 53 to start lowering the spindle 9 in order to mount the tool 3 indexed to the tool change position on the spindle 9 (S34). The spindle 9 moves away from the ATC origin and descends toward the machining area.

[0069] The CPU 31 determines whether the spindle 9 has moved away from the ATC origin as a condition for detecting that the spindle 9 is located within the tool change area (S35). The CPU 31 makes the determination in S35 based on the rotational position of the Z-axis motor 53 identified by the encoder 53A. If the CPU 31 determines that the spindle 9 has not moved away from the ATC origin (S35: NO), the CPU 31 returns the process to S35. If the CPU 31 determines that the spindle 9 has moved away from the ATC origin (S35: YES), the CPU 31 determines whether the control mode is the first mode (S36).

[0070] If the CPU 31 determines that the value of the mode flag is 0 and that the control mode is the first mode (S36: YES), it interrupts the power supply to the magazine motor 55, which had been resumed (S37). When the power supply to the magazine motor 55 is interrupted, the holding brake 55B is activated, and the state of the tool magazine 21 is maintained by the holding brake 55B. The CPU 31 proceeds to S38.

[0071] If the CPU 31 determines that the value of the mode flag is 1 and that the control 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 magazine motor 55, and the state of the tool magazine 21 is maintained by the magazine motor 55.

[0072] Based on the rotational position of the Z-axis motor 53 identified by the encoder 53A, the CPU 31 determines whether the spindle 9, which started to descend in S34, has reached the Z-axis origin, which is the upper end of the machining area (S38). If the CPU 31 determines that the spindle 9 has not reached the Z-axis origin (S38: NO), the CPU 31 returns the process to S38. If the CPU 31 determines that the spindle 9 has reached the Z-axis origin (S38: YES), the CPU 31 stops driving the Z-axis motor 53 to stop the descent of the spindle 9 (S39), and returns the process to S13 (see FIG. 5).

[0073] 5, 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 (S16) and returns the process to S 13. The various processes executed in S16 include, for example, a positioning process for the spindle 9 and a rotation process for the spindle 9.

[0074] 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 (S17) and returns the process to S2.

[0075] <Actions and Effects of the Present Embodiment> As described above, the numerical controller 30 detects the position of the spindle 9 in the Z-axis direction using the encoder 55A. The numerical controller 30 interrupts the power supply to the magazine motor 55 when in a standby state in which the tool magazine 21 is not in operation (S6, S37). When the numerical controller 30 replaces the tool 3 attached to the spindle 9 based on a tool change command, the CPU 31 detects the position of the spindle 9 in the Z-axis direction using the encoder 55A (S22) and resumes the power supply to the magazine motor 55 on the condition that it is detected that the spindle 9 is located within the tool change area (S25). When a tool change command is output in the numerical controller 30, the spindle 9 moves from the machining area to the tool change area, and the tool magazine 21 is rotated by driving the magazine motor 55. In the numerical controller 30, the power supply to the magazine motor 55 is resumed on the condition that it is detected that the spindle 9 is located within the tool change area. Therefore, compared to when the power supply to the magazine motor 55 is resumed at the time when a tool change command is output, the numerical control device 30 can reduce the power consumed by the magazine motor 55 while the spindle 9 moves from the machining area to the tool change area.

[0076] The numerical control device 30 resumes the power supply to the magazine motor 55 (S25) on the condition that it has detected that the spindle 9 is located at the ATC origin (S22: YES). In the numerical control device 30, the tool magazine 21 is rotatable when the spindle 9 is located at the ATC origin within the tool change area. When changing the tool 3 based on a tool change command, the numerical control device 30 drives the magazine motor 55 to rotate the tool magazine 21 when the spindle 9 reaches the ATC origin. In the numerical control device 30, the power supply to the magazine motor 55 is resumed just before the tool magazine 21 starts to rotate, so that the power consumption of the magazine motor 55 is further reduced.

[0077] The numerical control device 30 interrupts the power supply to the magazine motor 55 (S37) on the condition that rotation of the tool magazine 21 by the magazine motor 55 is completed (S32: YES) and the spindle 9 is detected to be located within the tool change area (S35). In the numerical control device 30, when rotation of the tool magazine 21 by the magazine motor 55 is completed, the spindle 9 moves from the machining area to the tool change area. In the numerical control device 30, on the condition that it is detected that the spindle 9 is located within the tool change area, the power supply to the magazine motor 55 is interrupted again. Thus, the numerical control device 30 can reduce the power consumed by the magazine motor 55 until the spindle 9 moves from the tool change area to the machining area.

[0078] The numerical controller 30 resumes the power supply to the magazine motor 55 (S31) on the condition that it has detected that the spindle 9 is located at the ATC origin within the tool change area (S22). Then, the numerical controller 30 interrupts the power supply to the magazine motor 55 (S37) on the condition that the rotation of the tool magazine 21 caused by the drive of the magazine motor 55 to which the power supply has been resumed has been completed (S32) and the spindle 9 has been detected to be located at the ATC origin (S35). In the numerical controller 30, power is supplied to the magazine motor 55 while the magazine motor 55 is driven (from time T3 to time T4), and when the rotation of the tool magazine 21 caused by the drive of the magazine motor 55 has been completed, the power supply to the magazine motor 55 is interrupted. Thus, the numerical controller 30 can further reduce the power consumption of the magazine motor 55.

[0079] The numerical control device 30 switches between a first mode (S7) in which the power supply to the magazine motor 55 is interrupted and a second mode (S5) in which power is constantly supplied to the magazine motor 55. This allows the numerical control device 30 to achieve specifications that match the machine tool 1.

[0080] <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.

[0081] 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.

[0082] 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.

[0083] The machine tool 1 may have any configuration as long as the spindle 9 is movable between the machining area and the tool changing area. The machine tool 1 is not limited to a vertical machine tool in which the spindle 9 extends vertically, but may also 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 also be movable in the X-axis direction or the Y-axis direction.

[0084] 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 change position. In the above embodiment, the tool magazine 21 is a turret type, but the tool magazine 21 may be, for example, an arm type. In the above embodiment, the tool magazine 21 operates by rotating the magazine body 22 around the center of the support shaft 25 as driven by the magazine motor 55, but the tool magazine 21 may perform an operation other than rotation. For example, the tool magazine 21 may operate by translating the magazine body 22 as driven by the magazine motor 55. In the above embodiment, the drive circuits 41 to 45 are provided in the numerical control device 30, but the drive circuits 41 to 45 may also be provided in the machine tool 1.

[0085] In the above embodiment, the numerical control device 30 detects the position of the spindle 9 in the Z-axis direction based on the rotational position of the Z-axis motor 53 identified by the encoder 53A. However, the numerical control device 30 may estimate the speed of the spindle 9 based on a command input to the drive circuit 43, and detect the position of the spindle 9 in the Z-axis direction based on the estimated speed.

[0086] In the above embodiment, the numerical control device 30 resumes the power supply to the magazine motor 55 on the condition that it is detected that the spindle 9 is located at the ATC origin. In contrast, the numerical control device 30 may resume the power supply to the magazine motor 55 on the condition that it is detected that the spindle 9 is located within the tool change area. That is, the power supply to the magazine motor 55 may be resumed when the spindle 9 is located at a position different from the ATC origin within the tool change area. An example of a position within the tool change area that is different from the ATC origin is the Z-axis origin at the bottom end of the tool change area.

[0087] In the above embodiment, when the rotation of the tool magazine 21 is completed and the spindle 9 moves away from the ATC origin in the tool changing area, the numerical control device 30 interrupts the power supply to the magazine motor 55. However, the numerical control device 30 may not interrupt the power supply to the magazine motor 55 in the tool changing area, but may interrupt the power supply to the magazine motor 55 after the spindle 9 is positioned in the machining area.

[0088] The numerical control device 30 may interrupt the supply of power to the magazine motor 55 when it determines that the rotation of the tool magazine 21 has been completed. In this case, the numerical control device 30 may determine that the rotation of the tool magazine 21 has been completed when the tool 3 to be attached to the spindle 9 has been indexed to the tool change position based on the rotation position of the magazine motor 55 identified by the encoder 55A. The numerical control device 30 may also determine that the rotation of the tool magazine 21 has been completed when a predetermined time has elapsed since the magazine motor 55 was driven.

[0089] In the above embodiment, the numerical control device 30 interrupts the power supply to the magazine motor 55 when it is detected that the spindle 9 is located at the ATC origin. In contrast, the numerical control device 30 may interrupt the power supply to the magazine motor 55 when it is detected that the spindle 9 is located within the tool change area. That is, when the rotation of the tool magazine 21 is complete, the numerical control device 30 may interrupt the power supply to the magazine motor 55 when the spindle 9 is located at a position within the tool change area that is different from the ATC origin. An example of a position within the tool change area that is different from the ATC origin is the Z-axis origin at the bottom end of the tool change area. The position of the spindle 9 that serves as the basis for determining whether to resume the power supply to the magazine motor 55 and the position of the spindle 9 that serves as the basis for determining whether to interrupt the power supply to the magazine motor 55 may be different positions as long as they are within the tool change area.

[0090] The numerical control device 30 may be further switchable to a control mode different from the first mode and the second mode. The numerical control device 30 may control the power supply to the magazine motor 55 in the first mode without switching the control mode.

[0091] <Others> The CPU 31 that executes the processing of S6 and S37 is an example of the "interruption unit" of the present invention. The processing of S6 and S37 is an example of the "interruption step" and "interruption processing" of the present invention. The CPU 31 that executes the processing of S22 and S35 is an example of the "position detection unit". The processing of S22 and S35 is an example of the "position detection step" and "position detection processing" of the present invention. The CPU 31 that executes the processing of S25 is an example of the "restart unit" of the present invention. The processing of S25 is an example of the "restart step" and "restart processing" of the present invention. The ATC origin is an example of the "specific spindle position" of the present invention. The CPU 31 that executes the processing of S4 and S6 is an example of the "switching unit" of the present invention.

[0092] REFERENCE SIGNS LIST 1 Machine tool 8 Z-axis movement mechanism 9 Spindle 20 Tool changer 21 Tool magazine 30 Numerical control device 31 CPU 53 Z-axis motor 53A Encoder 55 Magazine motor 55A Encoder 55B Holding brake

Claims

1. A numerical control device for controlling the operation of a machine tool, which is capable of mounting a tool and has a spindle movable between a machining area where a workpiece is machined using the tool and a tool changing area where the tool is changed, and a tool magazine capable of loading the tool and transporting the tool to be mounted on the spindle to a tool changing position 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 magazine is not operated; a position detecting unit that detects the position of the spindle; and a restarting unit that restarts the power supply to the servo motor interrupted by the interrupting unit on the condition that the position detecting unit detects that the spindle is located within the tool changing area. The numerical control device is characterized by comprising the above components.

2. The tool magazine is operable when the spindle is located at a specific spindle position within the tool changing area. The restarting unit restarts the power supply to the servo motor on the condition that the position detecting unit detects that the spindle is located at the specific spindle position. The numerical control device according to claim 1 is characterized by this.

3. The interrupting unit interrupts the power supply to the servo motor on the condition that the operation of the tool magazine by the servo motor is completed in a state where the power supply to the servo motor is restarted by the restarting unit. The numerical control device according to claim 1 is characterized by this.

4. The interrupting unit interrupts the power supply to the servo motor on the condition that the operation of the tool magazine by the servo motor is completed in a state where the power supply to the servo motor is restarted by the restarting unit and the position detecting unit detects that the spindle is located within the tool changing area. The numerical control device according to claim 3 is characterized by this.

5. The tool magazine is operable when the spindle is located at a specific spindle position within the tool change area. The restart unit resumes power supply to the servo motor on the condition that the position detection unit detects that the spindle is located at the specific spindle position. The interruption unit interrupts power supply to the servo motor on the condition that the operation of the tool magazine by the servo motor is completed in a state where power supply to the servo motor has been resumed by the restart unit and the position detection unit detects that the spindle has left the specific spindle position. The numerical control device according to claim 4, characterized in that.

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

7. A control method for controlling the operation of a machine tool, the machine tool comprising a spindle movable between a machining area where a tool can be mounted and machining of a workpiece using the tool is performed, and a tool change area where the tool is changed, and a tool magazine capable of loading the tool and configured to convey the tool mounted on the spindle to a tool change position by driving a servo motor. The control method includes an interruption step of interrupting power supply to the servo motor in a standby state where the tool magazine is not operated, a position detection step of detecting the position of the spindle, and a restart step of restarting the power supply to the servo motor interrupted by the interruption step on the condition that the position detection step detects that the spindle is located within the tool change area.

8. A computer that controls the operation of a machine tool comprising a spindle that can be equipped with a tool and is movable to a machining area where machining of a workpiece is performed using the tool and a tool change area where the tool is changed, and a tool magazine that can store the tool and conveys the tool to be mounted on the spindle to a tool change position by driving a servo motor. In a standby state where the tool magazine is not operated, an interruption process for interrupting power supply to the servo motor, a position detection process for detecting the position of the spindle, and a restart process for restarting the power supply to the servo motor interrupted by the interruption process on the condition that the spindle is detected to be located within the tool change area by the position detection process. A program characterized by causing the computer to execute the processes.

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