JP2001087913A - Controlling method and device for motor-driven chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controlling method and device for a motor-driven chuck capable of changing the grasping force white grasping a work. SOLUTION: This controlling method for a motor-driven chuck is to grasp a work by opening and closing grasping claws of the chuck supported by a frame installed on the body of a machine tool using a motor whose driving torque is controllable, wherein the controlling processes comprise entering the setting value of the claw grasping force for a work, storing the data to exhibit the relation between the grasping force and the driving torque or rotating amount of the motor, grasping the work with a first grasping force by the claws while the motor is controlled in accordance with the stored data, and changing the grasping force into a second grasping value through the control of the motor according to the data in the condition that the work is kept grasped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling an electric chuck for opening and closing a chuck of a machine tool by a driving motor, and more particularly to an electric chuck capable of changing a gripping force while gripping a workpiece. The present invention relates to a control method and an apparatus for the same.

[0002]

2. Description of the Related Art A chuck for gripping a workpiece is attached to a spindle end of a machine tool such as a lathe. It is known that the holding claws of the chuck are opened and closed by a hydraulic cylinder. However, a chuck driven by a hydraulic cylinder has a short opening / closing stroke of the gripping claws, and in order to grip a workpiece having a greatly different diameter, it is necessary to adjust or replace the gripping claws. The operating rate of machine tools was also decreasing.

[0003] The chuck is disclosed in Japanese Utility Model Publication No. 63-3896.
In some cases, the opening and closing of the gripping claws are driven by a servomotor as described in Japanese Patent Application Laid-Open No. 8 (1994) -108. In this method, the position of the gripping claw is indirectly detected by a sensor, and the opening position of the gripping claw at the time of starting gripping or releasing gripping is controlled to an appropriate position according to the size of the workpiece.

[0004] The gripping force of the workpiece by the chuck is:
Generally, a high gripping force is used in roughing, and a low gripping force is used in finishing. When changing the gripping force, if the gripping force can be changed while the workpiece is attached to the chuck, work efficiency is improved. Such a hydraulic chuck capable of changing the gripping force while attaching a workpiece is described in JP-A-62-2228307 and JP-A-3-184705. JP 6
Japanese Patent Application Laid-Open No. 2-228307 describes a chuck that changes the gripping force by switching the hydraulic pressure between high pressure and low pressure, and Japanese Patent Application Laid-Open No. Hei 3-184705 discloses a mechanism for switching the hydraulic pressure between high pressure and low pressure and a reaction force applying mechanism. Are described to change the gripping force.

[0005]

Problems to be Solved by the Invention
In the apparatus described in Japanese Patent Application Laid-Open No. 8968, in which the opening and closing of the gripper is driven by a servomotor, the open position of the gripper can be controlled, but the gripping force of the workpiece can be controlled. could not. Furthermore, it has not been possible to accurately control the gripping force of the workpiece from a low gripping force region to a high gripping force region. In addition, fine control by combining the position of the gripping claw on the closing side (gripping position) and the driving torque of the servomotor, switching of the moving speed of the gripping claw depending on the position of the gripping claw, and movement of the gripping claw according to the gripping force. The control for switching the speed could not be performed. For this reason, the workpiece cannot be gripped with an accurate gripping force, or the time required for gripping the workpiece has been increased.

The above-mentioned Japanese Patent Application Laid-Open No. 62-228307 has been disclosed.
In the hydraulic chuck described in Japanese Patent Application Laid-Open No. HEI 3-184705, the gripping force is switched by switching the hydraulic pressure, it is difficult to accurately control the gripping force due to the frictional force between the piston and the cylinder of the hydraulic mechanism. In particular, there is a problem that the gripping force on the low pressure side becomes unstable. Also, JP-A-62-228307 and JP-A-3-18470.
It was impossible at all to apply the switching of the gripping force as described in Japanese Patent No. 5 to the electric chuck. Further, there has not been conventionally known a method in which such switching of the gripping force is performed by an NC command of an NC machining program.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method and an apparatus for controlling an electric chuck, in which a chuck of a machine tool is driven to be opened and closed by a drive motor, the gripping force of which can be changed while the workpiece is being gripped. With the goal.

[0008]

In order to achieve the above object, a control method of an electric chuck according to the present invention is capable of controlling a driving claw of a chuck supported by a frame provided on a body of a machine tool. A method for controlling an electric chuck that grips a workpiece by opening and closing by a simple drive motor, comprising: inputting a set value of a gripping force that is a force of the gripping claw gripping the workpiece; A step of storing relation data indicating a relation between the driving torque or the rotation amount of the motor, a step of controlling the driving motor according to the relation data, and a step of gripping the workpiece with the first gripping force by the gripping claws; Holding the workpiece while controlling the drive motor in accordance with the relational data to change the gripping force of the gripping claw to a second gripping force different from the first gripping force. It is those having a power change procedure.

In the above-described electric chuck control method, it is preferable that the second gripping force is smaller than the first gripping force.

In the above-described method for controlling an electric chuck, the relation data may include a tightening grip indicating a relationship between the gripping force and the driving torque of the drive motor when the moving direction of the gripping claw is the gripping direction. Including force calibration data,
A step of storing a torque lower limit set value that is a drive torque corresponding to a gripping force smaller than the second gripping force,
The gripping force changing step includes controlling the driving torque of the driving motor according to the tightening gripping force calibration data after reducing the driving torque of the driving motor to the torque lower limit set value, and controlling the driving torque by the gripping claw. Preferably, the workpiece is gripped by a gripping force of 2.

In the above-described electric chuck control method, the relational data may include a tightening grip indicating a relationship between the gripping force and the driving torque of the drive motor when the moving direction of the gripping claw is the gripping direction. It is preferable to include force calibration data and loosening gripping force calibration data indicating a relationship between the gripping force and the driving torque of the drive motor when the moving direction of the gripping claw is the release direction.

In the above-mentioned electric chuck control method, in the gripping force changing step, the driving torque of the drive motor is controlled according to the loose gripping force calibration data, and the second gripping force is controlled by the gripping claw. It is preferable that the workpiece be gripped by the workpiece.

Further, in the above-described method for controlling an electric chuck, the drive motor is capable of controlling a rotation angle position, and the relation data is obtained from a state in which the drive motor grips a workpiece with the grip claws. The gripping force changing step includes a gripping force return amount data indicating a relationship between a return amount, which is an amount of rotation in a releasing direction, and the gripping force. Preferably, the gripping claw is returned in the release direction so as to grip the workpiece with the gripping force of 2.

In the above-described electric chuck control method, the drive motor is capable of controlling a rotation angle position, and the relation data is obtained from a state in which the drive motor grips a workpiece with the grip claws. Procedure for setting a reference gripping force that is greater than the second gripping force and equal to or less than the first gripping force, including gripping force return amount data indicating a relationship between the gripping force and a return amount that is an amount of rotation in the release direction. The gripping force changing step includes changing the driving torque of the driving motor to a value corresponding to the reference gripping force according to the loosening gripping force calibration data, and then controlling the driving motor according to the gripping force return amount data. It is preferable that the gripper is returned to the release direction so as to grip the workpiece with the second gripping force by controlling.

In the above-described electric chuck control method, in the gripping force changing step, the gripping state is confirmed by driving the drive motor in a gripping direction after gripping the workpiece with the second gripping force. Preferably, it includes a procedure.

In the above-described electric chuck control method, it is preferable that the gripping force changing procedure is executed by a command of an NC machining program.

Further, the electric chuck control device of the present invention is supported by a frame provided on the body of a machine tool,
A control device for controlling a chuck that grips a workpiece by opening and closing a gripping claw, wherein the gripping claw of the chuck is driven to open and close to control a gripping force that is a force with which the gripping claw grips a workpiece. A drive motor, input means for inputting a set value of the gripping force, means for storing relationship data indicating a relationship between the gripping force and the drive torque or the rotation amount of the drive motor, and the drive according to the relationship data. By controlling a motor, the workpiece is gripped by the gripping claw with a first gripping force, and while the workpiece is gripped, the drive motor is controlled in accordance with the relational data, and the gripping force of the gripping claw is controlled by the gripping force. Gripping claw control means for changing to a second gripping force different from the first gripping force.

[0018] In the control device for an electric chuck, it is preferable that the second gripping force is smaller than the first gripping force.

In the above-described control device for an electric chuck, the relation data may include a tightening grip indicating a relationship between the grip force and the drive torque of the drive motor when the moving direction of the grip claw is the grip direction. Including force calibration data,
Means for storing a torque lower limit set value that is a drive torque corresponding to a gripping force smaller than the second gripping force, wherein the gripping claw control unit sets the drive torque of the drive motor to the torque lower limit set value. Preferably, the driving torque of the drive motor is controlled in accordance with the tightening gripping force calibration data, and the workpiece is gripped by the gripping claw with the second gripping force.

In the above-described electric chuck control device, the relation data may include a tightening grip indicating a relationship between the grip force and the drive torque of the drive motor when the moving direction of the grip claw is the grip direction. It is preferable to include force calibration data and loosening gripping force calibration data indicating a relationship between the gripping force and the driving torque of the drive motor when the moving direction of the gripping claw is the release direction.

In the above-described electric chuck control device, the gripping claw control means controls the driving torque of the drive motor according to the loose gripping force calibration data, and the second gripping force is controlled by the gripping claw. It is preferable that the workpiece be gripped by the workpiece.

In the control device for an electric chuck, the drive motor can control a rotation angle position, and the relation data is obtained from a state in which the drive motor grips a workpiece with the gripping claws. It includes grip force return amount data indicating a relationship between a return amount that is an amount of rotation in the release direction and the grip force, and the grip claw control unit controls the drive motor according to the grip force return amount data. Preferably, the gripping claw is returned to the release direction so as to grip the workpiece with the second gripping force.

In the above-described control device for an electric chuck, the drive motor can control a rotation angle position, and the relation data is obtained from a state in which the drive motor grips a workpiece with the gripping claws. The gripping claw control means includes gripping force return amount data indicating a relationship between a return amount, which is an amount of rotation in a release direction, and the gripping force, wherein the gripping claw control means is larger than the second gripping force. After setting a reference gripping force equal to or less than the force, changing the driving torque of the driving motor to a value corresponding to the reference gripping force according to the loosening gripping force calibration data, controlling the driving motor according to the gripping force return amount data Preferably, the gripping claw is returned to the release direction so as to grip the workpiece with the second gripping force.

In the above-described electric chuck control device, the gripping claw control means checks the gripping state by driving the drive motor in the gripping direction after gripping the workpiece with the second gripping force. Preferably, it is

Further, in the above-described control device for an electric chuck, it is preferable that the gripping claw control means changes the gripping force according to a command of an NC machining program.

[0026]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a chuck 15 attached to a tip of a spindle 2 of an NC (numerical control) lathe as a machine tool to which the present invention is applied. FIG. 1 (b)
FIG. 2 is an enlarged cross-sectional view taken along the arrow BB in FIG. In addition,
The machine tool may be a turning center, a grinding machine, or the like.

The spindle 2 is rotatably supported by a headstock (not shown), and is rotationally driven by a spindle motor 4 (see FIG. 2). A face plate 12 is fixed in front of the spindle end 10 of the spindle 2 with bolts. On the front surface 81 of the face plate 12 fixed to the spindle end 10, a drive gear fixing plate 82 is provided with bolts 83.
It is fixed by. In the center hole of the driving gear fixing plate 82, a cylindrical scroll support tube 90 is rotatably supported via a rolling element 87 as a needle bearing. The scroll support cylinder 90 is integrated with the first member 21 extending forward.

A drive gear 86 is formed on the outer periphery of the drive gear main body 85 integrated with the drive gear fixing plate 82. As a result, the drive gear main body 85 is fixed to the main shaft 2. A bearing 95 is provided on the front outer periphery of the scroll support cylinder 90.
, A scroll 96 is rotatably supported and arranged. On the front end surface of the scroll 96, a spiral scroll groove 19 centering on the center line of the main shaft 2 is formed. Scroll teeth 28 formed on the rear surface of the master jaw 26 mesh with the scroll grooves 19.
The master jaw 26 is movable in a radial direction by a guide groove formed in the first member 21. Also, a plurality of master jaws 26 are provided at predetermined angles (for example, three).
Is provided. A gripping claw 30 is fixed to the master jaw 26.

First member 2 integrated with scroll support cylinder 90
An internal gear 97 is formed on the inner peripheral surface of the first gear 1. Between the drive gear 86 and the internal gear 97 described above, three intermediate gears 100 are arranged at equal angular positions and mesh with each other. The shaft 100a of the intermediate gear 100 is
6 is rotatably supported and disposed via a rolling element 102 as a needle bearing. After all, drive gear 8
6. The intermediate gear 100 and the internal gear 97 constitute a planetary gear mechanism, and play a role of a kind of reduction mechanism.

The second member 22 fixed integrally with the first member 21 has a positioning hole 41 formed therein. A fixing pin 45 is inserted into the positioning hole 41 to prevent the main body 20 including the first member 21 and the second member 22 from rotating with respect to the body of a machine tool such as a headstock. Fixing pin 45
Is provided at the center thereof with a supply passage for supplying pressurized air. When the fixing pin 45 is inserted into the positioning hole 41,
When the control valve (not shown) is opened, the pressurized air is
Is supplied to the positioning hole 41 from

An annular cylinder cylinder 111 is disposed and fixed to the second member 22. The cylinder chamber 11 which is an annular space between the second member 22 and the cylinder cylinder 111
0 is defined, and the cylinder chamber 110 has a rectangular cross section. An annular piston 112 is inserted into the cylinder chamber 110. The cylinder chamber 110 and the piston 112 constitute a pneumatically operated cylinder mechanism.

The pressurized air supplied from the fixing pin 45 to the positioning hole 41 passes through the second member 22 and the air supply passage 101 formed in the cylinder tube 111 to drive the piston 112. On the other hand, a clutch plate 113 is disposed behind the piston 112 so as to be in contact with the protrusion on the end face. Further, three guide pins 114 are arranged and fixed at equal angular positions in front of the drive gear fixing plate 82. An annular clutch plate 113 is disposed on the guide pin 114 so as to be able to move back and forth.

A coil spring 115 is arranged at an equiangular position behind the clutch plate 113. The coil spring 115 urges the piston 112 forward through the clutch plate 113. Clutch plate 113
A clutch tooth 116 is formed on the front end face of the clutch. Behind the second member 22 at a position facing the clutch teeth 116, clutch teeth 117 are formed. When the clutch teeth 116 and the clutch teeth 117 mesh with each other, the second member 22 and the main shaft 2 are fixed so as not to move relative to each other. At the time of machining, the clutch teeth 116 and the clutch teeth 117 are engaged by the urging force of the coil spring 115, and
And the main body 20 of the chuck 15 are fixed.

Next, the operation of the chuck 15 will be described. In order for the chuck 15 to grip the workpiece, first the NC
A spindle indexing command is sent from the device 50 (see FIG. 2) to the C-axis / spindle controller 410 to stop the spindle 2 at a predetermined angular position. Next, the fixing pin 45 is inserted into the positioning hole 41, and the main body 20 is brought into a fixed state in which the main body 20 cannot be rotated with respect to a machine body such as a headstock or a bed. When the fixing pin 45 is inserted into the positioning hole 41, the control valve is subsequently opened to apply pressurized air to the fixing pin 45.
From the positioning hole 41.

The positioning hole 4 passes through the center of the fixing pin 45.
The pressurized air supplied to 1 is supplied to the second member 22 and the air supply path 101 formed in the cylinder tube 111, and drives the piston 112. By driving the piston 112,
The clutch plate 113 compresses the coil spring 115 and moves backward. By this movement, the engagement between the clutch teeth 116 and the clutch teeth 117 is released. With this release, the second member 22 of the main body 20 and the main shaft 2 can rotate relative to each other.

With the main body portion 20 of the chuck 15 fixed, the main shaft 2 is driven to rotate by the main shaft motor 4 (see FIG. 2), and the driving gear 86, the intermediate gear 100, and the internal gear 9 are rotated.
The scroll 96 is rotated via the speed reduction mechanism 7 to open and close the gripping claws 30 to release or grip the workpiece. The drive torque of the main shaft 2 is increased by this speed reduction mechanism and transmitted to the scroll 96. When the release or gripping operation of the workpiece is completed, the fixing pin 45 is pulled out from the positioning hole 41, and the main body 20 of the chuck 15 is brought into a release state in which the main body 20 of the chuck 15 can be rotated with respect to a machine tool body such as a headstock. At the same time, the control valve (not shown) is closed to stop the supply of the pressurized air, so that the pressure of the pressurized air is lost, and the piston 112 moves forward by the urging force of the coil spring 115, and the clutch teeth 116 and The main shaft 2 and the main body 20 of the chuck 15 are fixed by the engagement of the clutch teeth 117. The workpiece held by the chuck 15 is now ready for machining.

In the above embodiment, the piston 112 is driven by pressurized air. However, when the fixing pin 45 is inserted into the positioning hole 41,
The piston 112 may be moved by a mechanical transmission mechanism.

FIG. 2 is a block diagram showing the configuration of the NC unit 50 and each control motor. As the NC device 50, control of a servomotor is provided in an expansion slot of a dedicated NC machine or a small personal computer (hereinafter, referred to as a personal computer).
A so-called personal computer NC equipped with an NC board for performing sequence control, etc., and having a numerical control function and a personal computer function
The device can be used. The NC device 50 is provided with a CPU 51 as information processing means for performing various data processing. The CPU 51 is connected to a ROM 53 and a RAM 54 as main storage devices via a bus 52.

The CPU 51 operates according to the system programs and data stored in the ROM 53 and the programs and data loaded into the RAM 54 (read into the memory). The programs loaded into the RAM 54 as described above include an OS (operating system), which is a basic program, and a large number of NCs.
An NC command processing program for performing a process corresponding to each NC command of the commands, and a chuck control program 54 for processing an NC command particularly related to the chuck opening / closing control among the NC commands.
1, a gripping claw position calculation program 542, a gripping force calculation program 543, a display control program for displaying characters and graphics on the display means 58, and the like.

The gripping claw position calculation program 542 is a program for calculating the correspondence between the position of the gripping claw 30 of the chuck 15 and the C-axis coordinate value of the spindle 2, and is obtained by calculating one from the other. Here, the C axis is a control axis for controlling the angular position of the main shaft 2 around the main axis. Gripping claw 3
The position of 0 is displayed and input by the diameter display.
In the device 50, the data is converted into C-axis coordinate values, stored and managed. The C-axis coordinate value and the position of the gripping claw 30 are in a proportional relationship if the origin is appropriately set.

That is, the C-axis coordinate value c and the gripping claw position d have a relationship of c = k · d. k is a conversion constant, which is a constant that depends on the reduction ratio of the drive from the main shaft 2, the pitch of the scroll 96, and the like. The moving amount and the speed are also converted by the same conversion constant k. The gripping claw position calculation program 542 converts the coordinate value, the movement amount, and the speed of the C-axis and the gripping claw with each other by using the conversion constant k. The display of the gripping claw position on the display means 58 is converted into a diameter value and displayed, and the input of the gripping claw position is also based on the diameter value, so that it is easy for the operator to understand.

The gripping force calculation program 543 is a program for calculating one from the other based on the correspondence between the driving torque of the spindle motor 4 and the gripping force of the gripping claws 30. Since there is an individual difference between the driving torque and the gripping force for each chuck 15 and the like, the correspondence between the driving torque and the gripping force is stored in the tightening gripping force calibration data area 552 and the loosening gripping force calibration data area 553 described later. Have been. The set value selection change program 544 is a program for selecting a set of chucking data stored in the chucking data memory 57 or changing the chucking data according to an instruction of the NC machining program.

A parameter memory 55 is connected to the CPU 51 via a bus 52. The parameter memory 55 stores various parameters required for processing. By using a non-volatile memory, the parameter memory 55 can retain the stored contents even when the power of the NC device 50 is turned off. The parameter memory 55 includes a chuck basic parameter area 551, a tightening grip force calibration data area 552, and a loose grip force calibration data area 55.
3. Each storage area such as a grip force return angle data area 554 is set.

The basic chuck parameter area 551 is a storage area for storing various basic chuck specific parameters of the chuck displayed on the chuck maintenance screen (see FIG. 4) of the display means 58. These chuck basic parameters are set by the machine tool maker. Normally, the user does not change the chuck basic parameters. The tightening grip force calibration data area 552 and the loose grip force calibration data area 553 are storage areas for storing grip force calibration data for calculating the relationship between the driving torque of the spindle motor 4 and the grip force of the chuck 15 of the chuck 15. It is.

The spindle motor 4 is rotated in the gripping direction (tightening direction) from the state where the workpiece is not gripped by the gripping claw 30 and is rotated in the release direction (loosening direction) from the state where the workpiece is gripped. In this case, as shown in FIG. 5, a curve is drawn in which the relationship between the driving torque of the spindle motor 4 and the gripping force of the gripper 30 is different. Clamping force calibration data area 55
Numeral 2 stores tightening grip force calibration data Da which is gripping force calibration data in the tightening direction. The loose grip force calibration data area 553 stores loose grip force calibration data Db which is grip force calibration data in the loosening direction. It is something to remember.

When the main spindle motor 4 is rotated by a return angle in the loosening direction after the workpiece is gripped by the gripping claw 30 with a predetermined gripping force, the gripping force decreases from a predetermined value in accordance with the return angle. . The grip force return angle data area 554 includes:
Gripping force return angle data D indicating the relationship between the return angle and the gripping force
This is a storage area for storing c, Dd, and De (see FIG. 6).

Further, an NC machining program memory 56 and a chucking data memory 57 are connected to the CPU 51 via a bus 52. The NC machining program memory 56 stores the workpiece from the chuck 15, grips the workpiece with the chuck 15, rotates the spindle, and moves the tool rest (not shown) and the spindle head relative to each other. An NC machining program for performing machining by performing movement control in the directions of an axis (a coordinate axis parallel to the main axis) and an X axis (a coordinate axis orthogonal to the Z axis) is stored. The chucking data memory 57 stores a chuck setting screen of the display means 58 (see FIG. 7).
Is a memory in which various data displayed in the memory are stored.
The chucking data is set by the user for each type of workpiece.

Input / output devices are connected to the CPU 51 via a bus 52. As input / output devices, a display means 58 for displaying characters and figures and an input means 59 for an operator to input data are connected to the bus 52 via an interface circuit. As the display means 58, CR
T, EL display panel, liquid crystal display, etc. can be used,
As the input means 59, a keyboard, a touch panel integrated with the display means 58, or the like can be used.

Further, a fixed disk device as an auxiliary storage device may be connected to the CPU 51 via a bus 52. In this case, the fixed disk device has a CPU 5
Various programs and the like to be executed by the computer 1 may be stored, and these programs and the like may be loaded from the fixed disk device into the RAM 54 and the NC machining program memory 56 as appropriate.

The NC device 50 includes a C-axis / spindle controller 41.
0, connected via an amplifier 411 to the spindle motor 4 of the NC lathe. The rotation speed of the spindle motor 4 is fed back to the amplifier 411 via the detector 412, and the predetermined rotation speed is maintained. The angular position of the spindle 2 around the C axis is determined by the detector 412 and the amplifier 411 and the C axis / spindle controller 41.
This is fed back to 0, and the speed and position of the main shaft 2 can be controlled in the C-axis direction to position the main shaft 2 at a desired angular position.

Similarly, the NC device 50 is connected to the X-axis motor 6 of the NC lathe via the X-axis positioning control unit 61 and the amplifier 62, so that the workpiece and the tool rest can move in the X-axis direction (Z-axis direction). (Relative direction). The number of rotations and the rotation angle of the X-axis motor 6 are determined by an amplifier 62 via a detector 63.
Is fed back to the X-axis positioning control unit 61 and is used for controlling the speed and position of the relative movement of the tool post in the X-axis direction. Z-axis motor 7, Z-axis positioning controller 71, amplifier 7
2. The function of the detector 73 is the same as that for the X axis, and controls the relative movement of the workpiece and the tool rest in the Z axis direction (a direction parallel to the main axis direction).

The NC device 50 is connected via a PLC (Programmable Logic Controller) 500 to a foot switch 501, a door closing confirmation switch 502, a mode changeover switch 511, and an inside / outside tightening changeover switch 512. The foot switch 501 is for the chuck 1
5 is a foot switch for manually opening and closing 5.
The door closing confirmation switch 502 is a sensor for confirming that the opening / closing door that covers the processing area of the NC lathe is in a closed state.

The mode switch 511 is connected to the chuck 1
A switch for manually switching the operation mode 5 between the machining mode and the chucking mode. The inside / outside tightening changeover switch 512 is a switch for switching a gripping direction of the workpiece (whether to grip the inner diameter or the outer diameter). Although not shown, an actuator for driving the fixing pin 45, a position sensor for detecting the insertion or removal state of the fixing pin 45, and the like are also connected to the PLC 500.

FIG. 3 shows an operation panel 510 of the chuck 15.
FIG. 3 is a diagram showing the configuration of FIG. The operation panel 510 is provided with the mode changeover switch 511 described above. The cut-out portion 511a is set to one of “machining” and “chucking”, and pressing the center of the mode changeover switch 511 is effective. The chucking mode is a mode in which the workpiece is held or released by the chuck 15.
The processing mode is a mode for processing a gripped workpiece. The LED 515 is turned on in the processing mode, and the LED 516 is turned on in the chucking mode. Further, at the time of the switching operation to the chucking mode, the state of the door close confirmation switch 502 is detected, and if the open / close door is not in the closed state, a warning is displayed and the chucking operation is not performed. Therefore, the safety of the worker is ensured.

The setup opening / closing switch 514 is a push button switch.
And "OFF". Setup open / close mode is “On”
In this state, the push button itself is turned on. The setup opening / closing mode is a mode in which the operator manually moves the gripping claws 30. The inside / outside tightening changeover switch 512 is a switch for switching between gripping the workpiece from the inner diameter side (inner tightening) and gripping the workpiece from the outer diameter side (outer tightening).

The grip release switch 513 is a toggle switch for switching the moving direction of gripping or releasing the workpiece. When the lever is tilted to the “tightened” side, the grip direction,
If you tilt it to the "loose" side, you will select the release direction.
In the setup opening / closing mode, the operator operates the internal / external tightening changeover switch 5.
12. The moving direction of the grip claw 30 is selected by the grip release switch 513, and the grip claw 30 is moved by pressing the foot switch 501 with the foot. The grip claw 30 moves only while the foot switch 501 is on.

FIG. 4 is a diagram showing a chuck maintenance screen displayed on the display means 58 of the NC device 50. This screen is displayed when the machine tool maker displays the chuck basic parameter area 55.
1 is a screen for setting the basic chuck parameters or performing maintenance of the machine tool. The user cannot change the basic chuck parameters from this screen. The chuck basic parameters include hardware basic parameters and software basic parameters as shown on the screen.

These are parameters specific to the chuck of each machine tool. By using a cursor key (not shown), the cursor position can be changed, and each parameter can be changed and set. In the line at the cursor position, the first heading character is displayed in reverse video and an underline is additionally displayed.
In FIG. 4, the cursor is located on the line of the C-axis command speed V1, and this value can be set. Further, when the "setting" key of the function key is pressed from this screen, a chuck setting screen of FIG. 7 is displayed.

The hardware basic parameters will be described. The maximum input torque is the value of the maximum drive torque of the spindle motor 4. The maximum gripping force is a gripping force when the maximum drive torque of the spindle motor 4 is generated, and the minimum gripping force is a lower limit of a gripping force capable of gripping a workpiece. The gripping force setting unit is a unit amount of the gripping force setting. The unit of these forces is
It is kgf (kilogram weight), but it can be set as N (Newton).

The reduction ratio in the chuck is a reduction ratio of the rotation transmission from the main shaft 2 to the scroll 96. The scroll pitch is the pitch of the scroll groove 19 of the scroll 96. The internal clutch tooth pitch is a pitch between the clutch teeth 116 and 117 of the clutch plate 113 and the second member 22. The stop position of the main shaft 2 must be a position for each angle of the internal clutch tooth pitch (a position where the clutch teeth 116 and 117 can be engaged).

Next, the software basic parameters will be described. The stroke upper limit is a stroke limit value on the maximum diameter side of the gripping claw 30. The stroke lower limit is a stroke limit value on the minimum diameter side of the gripping claw 30. The torque limit value T1 is a torque limit value at the time of high-speed movement or release operation of the gripping claw 30. T1 is entered as a percentage of the maximum torque. The torque limit value may be a torque value (kgf · m, Nm) instead of a percentage.

The C-axis command speed V1 is a C-axis moving speed at the time of high-speed movement of the gripping claw 30, and is, for example, a C-axis rapid feed speed. The C-axis command speed V2 is a C-axis moving speed when the gripping claw 30 moves at a low speed (during a gripping operation or the like). The C-axis command speed V3 is the C-axis moving speed when the gripping claw 30 moves at an extremely low speed (such as when moving from the stop point to the gripping point). C axis command speed V
4 is a state in which the spindle motor 4 is rotated in a loosening direction until a predetermined driving torque is reached from a state in which the workpiece is gripped with a predetermined gripping force, or the spindle motor 4 is rotated in a loosening direction by a predetermined return angle. This is the C-axis moving speed when the force is reduced. The C-axis command speed V4 is preferably equal to or lower than the C-axis command speed V3. When the C-axis command speeds V3 and V4 are the same, C
The axis command speed V4 can be omitted. V1 to V
The unit of 4 is rotation / minute.

FIG. 5 shows a gripping force calibration curve showing the relationship between the driving torque of the spindle motor 4 and the gripping force of the gripping claws 30. The relationship between the driving torque and the gripping force is such that when the spindle motor 4 is rotated in the gripping direction (tightening direction) of the gripping claw 30, the calibration curve displayed by the tightening gripping force calibration data Da is indicated by an arrow on the upper right. Go to When rotating the spindle motor 4 in the release direction (loose direction), the main shaft motor 4 moves to the lower left on the calibration curve displayed by the loose grip force calibration data Db as indicated by the arrow. The tightening grip force calibration data Da is stored in the tightening grip force calibration data area 552, and the loose grip force calibration data Db is stored in the loose grip force calibration data area 553.

For example, when the workpiece is gripped from the
When gripping at 00 kgf, tightening gripping force calibration data Da
A driving torque corresponding to the holding force of 5000 kgf is set, and the spindle motor 4 is rotated until the driving torque is reached to grip the workpiece. At this time, the gripping force increases along the calibration curve of the tightening gripping force calibration data Da when the driving torque increases. Gripping force 50 of tightening gripping force calibration data Da
When the driving torque corresponding to 00 kgf is reached, the spindle motor 4 is stopped.

Next, when the gripping force is reduced to 3000 kgf from the state where the workpiece is gripped at 5000 kgf, the gripping force of the loosening gripping force calibration data Db is 3000 kgf.
A drive torque corresponding to f is set, and the spindle motor 4 is rotated in the loosening direction. Initially, a state in which the gripping force does not decrease even when the drive torque is reduced occurs. From the calibration curve of the tightening gripping force calibration data Da to the calibration curve of the loosening gripping force calibration data Db, almost as shown by the broken arrow A. Move horizontally. Further, when the spindle motor 4 is rotated in the loosening direction,
In response to the decrease in the driving torque, the gripping force is loosened and decreases along the calibration curve of the gripping force calibration data Db. When the driving torque corresponding to the holding force of 3000 kgf in the loosening holding force calibration data Db is reached, the spindle motor 4 is stopped.

The workpiece is gripped 3000 kg from the gripping direction.
When the gripping force is increased to 5000 kgf after gripping by f, the driving torque is increased along the calibration curve of the tightening gripping force calibration data Da to increase the gripping force.

Further, when the workpiece is released in the loosening direction,
When the gripping force is increased to 5000 kgf after the gripping change to kgf, the gripping force 5 of the tightening gripping force calibration data Da is used.
A driving torque corresponding to 000 kgf is set, and the spindle motor 4 is rotated in the gripping direction. Initially, a state occurs in which the gripping force does not increase even if the driving torque is increased, and the tightening gripping force calibration data D is obtained from the calibration curve of the loosening gripping force calibration data Db.
It moves substantially horizontally toward the calibration curve a as shown by the dashed arrow B. Further, when the spindle motor 4 is rotated in the gripping direction, the gripping force increases along the calibration curve of the tightening gripping force calibration data Da in response to the increase in the driving torque. When the driving torque corresponding to the gripping force of 5000 kgf in the tightening gripping force calibration data Da is reached, the spindle motor 4 is stopped.

When the spindle motor 4 is rotated in the tightening direction and the loosening direction while controlling the torque, the gripping force increases and decreases in the above-described process. That is, in both the tightening direction and the loosening direction, it is possible to calculate the driving torque for generating a desired gripping force from the tightening gripping force calibration data Da and the loosening gripping force calibration data Db. This calculation is performed by the gripping force calculation program 543.

FIG. 6 is a diagram showing a grip force return angle relationship curve showing the relationship between the return angle and the grip force. After the workpiece is gripped by the gripping claw 30 with a predetermined gripping force (initial value), when the spindle motor 4 is rotated by a return angle in the loosening direction, the gripping force decreases from the initial value according to the return angle. The relationship curve displayed by the gripping force return angle data Dc indicates that the gripping force is 60
It shows the relationship between the return angle and the gripping force when the spindle motor 4 is returned in the loosening direction from the state where the gripper is held at 00 kgf. Similarly, the relationship curves displayed by the gripping force return angle data Dd and De indicate that the gripping force is 4000 kgf, respectively.
It shows the relationship between the return angle and the grip force when returning from a state of 2000 kgf.

As can be seen from FIG. 6, when the initial value of the gripping force is known, it is possible to calculate what value the gripping force is reduced by the return angle of the spindle motor 4. Also,
A return angle for obtaining a desired gripping force can be calculated. These calculations are performed by the gripping force calculation program 543. Gripping force return angle data Dc, Dd, De required for calculation
Are stored in the gripping force return angle data area 554.
When the gripping force is controlled based on the gripping force return angle data Dc, Dd, and De, stable control can be performed up to a low gripping force region.

The tightening gripping force calibration data Da and loose gripping force calibration data Db shown in FIG. 5 and the gripping force return angle data Dc, Dd, De shown in FIG. 6 are data unique to each chuck. These data are set by the machine tool maker. When a "calibration" key of the function key is pressed from the chuck maintenance screen of FIG. 4, a screen for setting these data is displayed, and these data can be input and changed.

FIG. 7 is a view showing a chuck setting screen displayed on the display means 58 of the NC device 50. As shown in FIG. Various chucking data stored in the chucking data memory 57 are displayed on the chuck setting screen. As these chucking data, one set of chucking data is stored for each type of workpiece (type of machining) and the like, and a plurality of sets of the chucking data are stored. The chucking data can be freely set by the user.

The chucking data will be described. The parameter group No. is a number assigned to a set of chucking data. The machining program No. is the program number (O number) of the NC machining program that uses this set of chucking data. The gripping force is a set value of the gripping force for gripping the workpiece. The setting unit can be kgf (kilogram weight) or N (Newton). The data of the gripping force is converted into a torque limit value T2 of the spindle motor 4 and stored.

The grip diameter is a set value of the workpiece gripping position. The shift point is a set value of a position at which the gripper 30 is shifted from a high-speed movement to a low-speed movement. The evacuation point is a set value of the evacuation position of the grip claw 30, that is, the start position of the grip operation. Both the shift point and the retreat point are values displayed in diameter. The core diameter is a diameter value of a core used when processing the gripping nail as a raw nail. The error detection level is used when calculating an error between the position of the gripping claw 30 at the time when the workpiece is gripped and the set gripping diameter to determine a gripping error. If the error is outside the set value of the error detection level, a gripping error is determined. The error detection level is input as a percentage of the grip diameter. It should be noted that the error detection level may be input not as a percentage but as an allowable set value (mm).

The operator can set these chucking data, assign a desired parameter group No., and save it. Also, the saved set of chucking data can be called at any time. The input of the chucking data can be performed by changing the cursor position using a cursor key (not shown) and inputting or changing each data. In the line at the cursor position, the first heading character is displayed in reverse video and an underline is additionally displayed.
In FIG. 7, the cursor is on the line of the grip diameter, and this value can be input. Below the chucking data, the data of the current position and the stop point of the gripping claw 30 are displayed. On the right side of the screen, an image indicating the positional relationship between the retreat point, the shift point, and the stop point is displayed.

Note that these chucking data are NC
It can be changed from the machining program. Further, the selection of the parameter group can also be performed from the NC machining program. The selection of the parameter group and the change of the chucking data by the command of the NC machining program are performed by the set value selection change program 544.

When the "maintenance" key of the function key is pressed on the screen of FIG. 7, the chuck maintenance screen of FIG. 4 is displayed. "Teaching"
The key teaches the diameter of the workpiece gripped by the gripper of the gripper 30 and performs an operation for matching the gripper position managed by the NC device 50 with the actual gripper position of the gripper 30. Things. For example, when the gripping claw 30 is a raw nail, the gripping portion is formed according to the shape of the workpiece, so that the shape of the gripping portion and the size of the gripping position are deviated each time processing is performed.

When the gripping claw 30 is formed and the gripping position dimensions and the like are deviated, an object to be gripped having a known diameter is gripped by the formed gripping portion of the gripping claw 30 of the chuck 15 and the chuck setting screen is displayed. A known diameter value is input as the grip diameter.
Then, when the “teach” key is pressed, the current position of the gripping claw 30 is rewritten to the input known diameter value, and the NC device 50 is pressed.
The position of the gripping claw in the inside and the actual gripping position of the gripping claw 30 match. The processing of this teaching is performed by the chuck control program 54.
1 is performed.

The "list" key of the function keys is for displaying a list of a plurality of registered chucking data sets. A plurality of (for example, 40) sets of chucking data can be registered in the chucking data memory 57. From among the plurality of sets, one used in the processing to be executed can be selected and called on the screen. The “delete” key is used to delete the currently displayed set of chucking data. "Erase"
Pressing the key deletes the currently displayed set of chucking data from the chucking data memory 57.

FIG. 8 is a diagram showing the control of the position and speed of the gripping claw 30 when the chuck 15 is normally opened and closed. The normal opening / closing means the mode changeover switch 511 on the operation panel 510.
In the chucking mode to automatically grip and release the workpiece. FIG. 8A shows the case of normal gripping with external fastening in normal opening and closing. The work is set with the gripping claw 30 in the retracted position, the opening / closing door is closed, and the mode changeover switch 51 on the operation panel 510 is set.
1 is switched to the chucking mode. When the foot switch 501 is depressed once, the grip claw 30 moves at a high speed V1 from the retreat point to the shift point, and further moves at a low speed V2 from the shift point to the stop point.

When the gripper 30 grips the workpiece and the driving torque of the spindle motor 4 reaches a torque limit value (torque setting value) T2 corresponding to the gripping force, the movement is stopped. The stop position of the main shaft 2 (the gripping point of the gripping claw 30) is
16, 117 must be at a position at each predetermined angle at which meshing is possible. For this purpose, control is performed such that the gripping claw 30 moves at the extremely low speed V3 from the stop point due to the torque limit value T2 to the grip points at these predetermined angles, and stops at the nearest grip point.

FIG. 8B shows an example in which an error occurs in the gripping of the outer fastening during normal opening and closing. The gripping claw 30 moves at a high speed V1 from the retreat point to the shift point, and moves at a low speed V2 from the shift point to the stop point. If normal, the driving torque of the spindle motor 4 is equal to the torque limit value T2 corresponding to the gripping force.
, The movement is stopped. In this case, the torque limit value T2 is not reached even if the position exceeds a predetermined distance from the stop point, and an error has occurred. Since this error may be an empty machining (operation of operating the machine tool without attaching the workpiece to the chuck and confirming the machining operation), it is not necessary to output an error signal or the like.

FIG. 8 (c) shows a case where the outer fastening is released during normal opening and closing. The grip claw 30 moves at a high speed V1 from the grip point to the retreat point. Note that the normal opening / closing operation as described above is performed by replacing the operation of the foot switch 501 or the like with N
The operation may be performed by a command of the C machining program (for example, a command of the auxiliary function).

FIG. 9 is a diagram showing the control of the position and speed of the gripping claws 30 in the setup opening / closing mode of the chuck 15.
The setup opening / closing mode is a mode in which the setup opening / closing switch 514 of the operation panel 510 is set to “ON”, and the operator manually moves the gripping claw 30. The operator operates the grip claw 3 by using the inside / outside tightening switch 512 and the grip release switch 513.
The moving direction of 0 is selected, and the gripper 30 is moved by pressing (turning on) the foot switch 501 with the foot. The grip claw 30 moves only while the foot switch 501 is on.

FIG. 9 (a) shows a case in which the outer clamp is used for setup opening and closing. The gripping claw 30 moves from the current position to the stop point at a low speed V2 by pressing the foot switch 501. When the gripping claw 30 grips the workpiece and the driving torque of the spindle motor 4 reaches a torque limit value T2 corresponding to the gripping force, the movement is stopped. The control in which the gripping claw 30 moves at a very low speed V3 from the stop point by the torque limit value T2 to the gripping point for each predetermined angle and stops at the nearest gripping point is shown in FIG.
Same as (a).

FIG. 9 (b) shows the gripping claws 3 during setup opening and closing.
0 is simply moved in the gripping direction (tightening direction).
The gripping claw 30 moves from the current position in the gripping direction at a low speed V2 by pressing the foot switch 501, and stops at a position where the foot switch 501 is released. FIG. 9 (c) shows the case of the inner clamping in the setup opening and closing. This is the same as the speed control of FIG. 9A, except that the moving direction is different. FIG.
(D) shows a case where the grip claw 30 is simply moved in the release direction (loosening direction) in setup opening and closing. This is also the same as the speed control in FIG. 9B except that the moving direction is different.

FIG. 10 is a flowchart showing the control of gripping in the normal opening and closing of the chuck 15. This shows the processing in the case of the control of FIGS. 8A and 8B. The program for performing this processing is included in the chuck control program 541, and is called from the main routine of the chuck control program 541. When the normal gripping operation is started, in a process 601, the movement of the gripping claw 30 is started at a high speed V1 and a torque limit value T1 from the retreat point to the shift position.

In the next judgment 602, it is judged whether or not the drive torque of the spindle motor 4 has reached the torque limit value T1. If the torque limit value T1 has been reached, the process proceeds to step 615. At this point, reaching the torque limit value T1 is an abnormal state such as a different type of workpiece. In process 615, a movement stop command is sent to the C-axis / spindle control unit 410, and the
0 is abnormally stopped. Next, it waits until the stop is completed in a judgment 616, and if the stop is completed, an alarm signal is output in a process 617, and the process returns to the calling source.

When the torque limit value T1 has not been reached in the judgment 602, it is judged in a judgment 603 whether or not the movement to the shift point has been completed. If not completed, judge 6
02, and if it has been completed, the process proceeds to step 604. Processing 6
In step 04, a grip position, which is a position obtained by adding a stop position allowable error to a position on the C axis corresponding to the grip diameter, is calculated. In addition,
A predetermined value may be added instead of the stop position allowable error. The calculation is performed by the gripping claw position calculation program 542. In the next process 605, the movement of the grip claw 30 is started at the low speed V2 and the torque limit value T2 to the calculated grip position.

In the next judgment 606, it is judged whether or not the drive torque of the spindle motor 4 has reached the torque limit value T2. If the torque limit value T2 has not been reached, the judgment 60
Proceeding to 7, it is determined whether the movement to the grip position has been completed. If it is not completed, the process returns to decision 606, and if it is completed, the process returns to the caller. At this point, the movement is completed in an abnormal state such as when the workpiece is not set.
Although an error signal or the like may be output, the error signal is not output here in consideration of the case of blank machining. Even in this case, since a grip signal described later is not output, it can be recognized that normal grip is not performed.

If the drive torque of the spindle motor 4 has reached the torque limit value T2 in the judgment 606, this is a normal case and the process proceeds to step 608. In the process 608, the grip claw 3
The true current position on the C axis of 0 is calculated. The true current position is a value obtained by subtracting the C-axis servo delay amount from the current C-axis coordinate value. Next, the routine proceeds to processing 609, where the clutch engagement position closest to the true current position is calculated. The clutch engagement position is a position where the clutch teeth 116 and 117 can engage. Next, the process proceeds to step 610, in which the movement of the gripping claw 30 is started up to the closest clutch engagement position without the extremely low speed V3 and no torque limitation.

Next, in a decision 611, the process waits until the movement is completed, and when the movement is completed, the process proceeds to a decision 612 to determine whether or not the stop position is within an allowable error (error detection level). If the error is within the allowable error, a gripping signal for confirming that the gripping has been normally completed is output in step 613, and then the process returns to the calling source. If the error is not within the allowable error, a gripping error signal indicating a gripping diameter abnormality is output in step 614, and the process returns to the calling source.

As described above, when the driving torque of the spindle motor 4 reaches the torque limit value T2 and the gripping pawl 30 stops within an allowable error from the gripping position set, a gripping signal for confirming normal gripping is issued. Since this is output, the reliability of the gripping operation is improved. For example, if the gripping confirmation is performed only at the position of the gripping claws as in the related art, a so-called empty gripping state in which the gripping operation is performed without the workpiece cannot be detected. Further, if the grip is confirmed only by the driving torque, it is not possible to detect a mistake in the type of the workpiece. By performing gripping confirmation using both the driving torque and the position of the gripping claw, a highly reliable gripping signal for confirming the gripping operation can be output.

If the control is performed to permit the rotation of the spindle by detecting the grip signal, the safety of the operation of the machine tool is improved. Whether the rotation of the spindle is permitted by checking the grip signal or whether the rotation of the spindle is permitted regardless of the presence or absence of the grip signal can be selectively switched by an operator. Further, it is preferable that this switching can be performed from the NC machining program.

Since the above-described control is performed, the gripping claw 30 is moved at a high speed at a position away from the gripping position, and the gripping claw 30 surely grips the workpiece at a low speed near the gripping position. The workpiece can be gripped with the set gripping force. Thereby, it is possible to perform an optimal grip according to the rigidity of the workpiece in a short time. Also, both the driving torque (gripping force) of the spindle motor 4 and the position of the gripping claw 30 allow
Since the normal gripping of the workpiece is checked, the reliability and safety of the machine tool are improved.

Here, the movement from the stop position to the clutch engagement position is performed for the closest clutch engagement position, but may be changed according to the set gripping force. That is, when the gripping force is near the maximum torque, the gripper moves to the clutch engagement position in the direction in which the gripper is loosened, and when the gripping force is near the minimum torque, the gripper moves to the clutch engagement position in the direction in which the gripper tightens. At the intermediate torque, the clutch moves to the clutch engagement position closest to the current position. Such movement control may be used.

FIG. 11 is a flowchart showing release control in the normal opening and closing of the chuck 15. This shows the processing in the case of the control in FIG. A program for performing this processing is a chuck control program 541.
And the chuck control program 541.
Is called from the main routine. When the normal release operation is started, in a process 621, the movement of the gripping claw 30 is started from the gripping position to the retreat point at a high speed V1 and a torque limit value T1.

In the next judgment 622, it is judged whether or not the driving torque of the spindle motor 4 has reached the torque limit value T1. If the torque limit value T1 has been reached, the process proceeds to step 624. At this point, the torque limit value T1 is reached due to an abnormal state such as clogging by chips. In the process 624, a movement stop command is sent to the C-axis / spindle control unit 410, and the grip claw 30 is abnormally stopped. Next, it waits until the stop is completed in a judgment 625, and if the stop is completed, an alarm signal is output in a process 626, and the process returns to the calling source. At decision 622,
If the torque limit value T1 has not been reached, it is determined in decision 623 whether the movement to the evacuation point has been completed. If it is not completed, the process returns to decision 622, and if it is completed, the process returns to the caller.

FIG. 12 is a flowchart showing the control of the gripping in the setup opening and closing of the chuck 15. This shows the processing in the case of the control of FIGS. 9A and 9C. The program for performing this processing is included in the chuck control program 541, and is called from the main routine of the chuck control program 541. When the setup gripping operation is started, in a process 631, the movement of the gripping claws 30 is started at the low speed V2 and the torque limit value T2 from the current position in the gripping direction. The gripping direction is the lower limit direction of the stroke when the external tightening is performed, and is the upper limit direction of the stroke when the internal tightening is performed.

In the next judgment 632, it is judged whether or not the drive torque of the spindle motor 4 has reached the torque limit value T2. If the torque limit value T2 has not been reached, the judgment 63
Proceed to 3 to determine whether the stroke limit has been reached.
If the stroke limit has not been reached, proceed to decision 634,
If it has, return to the caller. The movement is completed at this time because the engagement between the scroll teeth 28 of the master jaw 26 and the scroll groove 19 of the scroll 96 is disengaged, the engagement is reduced, and a predetermined gripping force is not generated with respect to the driving torque. This is so as not to cause a problem.

In the judgment 634, it is judged whether or not there is a stop command from the operator, that is, whether or not the stepping on the foot switch 501 is stopped.
2, if there is a stop command, the process proceeds to step 635 to send a movement stop command to the C-axis / spindle control unit 410 and
To stop. The stop position does not have to be a position in consideration of the engagement of the clutch teeth, but in this case, it is necessary to move the fixing pin 45 to a position in consideration of the engagement of the clutch teeth before the operation of pulling out the fixing pin 45 from the positioning hole 41. Occurs. Next, it waits until the stop is completed in the judgment 636, and returns to the calling source when the stop is completed.

If the drive torque of the spindle motor 4 has reached the torque limit value T2 in the judgment 632, it means that the workpiece has been gripped, and the process proceeds to step 637. In step 637, the true current position of the gripper 30 on the C axis is calculated. Next, the routine proceeds to step 638, where the clutch engagement position closest to the true current position is calculated. Next, the process proceeds to step 639, in which the movement of the gripping claw 30 is started to the nearest clutch engagement position without the extremely low speed V3 and no torque limitation. Next judgment 6
At 40, the process waits until the movement is completed, and when the movement is completed, a gripping signal indicating that gripping has been normally completed is output at step 641, and then the process returns to the calling source.

FIG. 13 is a flowchart showing the control of release of the chuck 15 during setup opening and closing. The program for performing this processing is included in the chuck control program 541, and is called from the main routine of the chuck control program 541. The setup release is an operation of releasing the workpiece in the setup opening / closing mode. When the setup release operation is started, in process 651, the gripping claw 30 starts moving from the current position in the release direction at a low speed V2 and a torque limit value T1. The release direction is the upper limit direction of the stroke when the external tightening is performed, and is the lower limit direction of the stroke when the internal tightening is performed.

In the next judgment 652, it is judged whether or not the drive torque of the spindle motor 4 has reached the torque limit value T1. If the torque limit value T1 has been reached, the routine proceeds to processing 657. At this point, the torque limit value T1 is reached due to an abnormal state such as clogging by chips. In process 657, a movement stop command is sent to the C-axis / spindle control unit 410, and the grip claw 30 is stopped abnormally. Next, it waits until the stop is completed in the judgment 658, and if the stop is completed, an alarm signal is output in a step 659, and the process returns to the calling source.

If the torque limit value T1 has not been reached in the judgment 652, it is judged in a judgment 653 whether or not the stroke limit has been reached. If the stroke limit has not been reached, the procedure proceeds to decision 654, and if it has, the procedure returns to the calling source. In the judgment 654, it is judged whether or not there is a stop command from the operator. If there is no stop command, the process returns to the judgment 652. The nail 30 is stopped. Next, in a decision 656, the process waits until the stop is completed, and returns to the calling source when the stop is completed. As described above, in the setup opening / closing operation, the operator performs the opening / closing operation, so that the gripping claw 30 is moved at the low speed V2 and not moved at the high speed V1 for safety.

In the present invention, it is possible to change the gripping force while holding the workpiece. To change the gripping force,
First, the main shaft 2 is stopped at a predetermined angular position, and a fixing pin 45 is inserted into the positioning hole 41 to fix the main body 20 of the chuck 15 in a fixed state. After that, the gripping force is changed by moving the gripping claw 30 in the tightening direction or the loosening direction by the spindle motor 4. Performs primary processing such as roughing by firmly gripping a workpiece with a high gripping force, and then changes the gripping force to a low gripping force and finishes the workpiece with high accuracy without causing distortion due to the gripping force Secondary processing such as can be performed.

As described above, the gripping force can be changed while holding the workpiece without removing the workpiece, thereby improving work efficiency. In addition, since the workpiece is not removed once, the gripping position of the workpiece does not change, and the common workpiece coordinates can be used for the primary processing and the secondary processing,
High-efficiency and high-precision processing becomes possible. 14 to 1
9 is a flowchart showing control for changing the gripping force while holding the workpiece. The processing of FIG. 14 to FIG.
This is included in the chuck control program 541.
After the chuck 15 is fixed, each process is called to change the gripping force, and
Is released, and the next secondary processing is performed.

FIG. 14 is a flowchart showing the control for increasing the grip force in the grip force change control. First, in process 701, a driving torque corresponding to the changed gripping force is obtained from the tightening gripping force calibration data Da shown in FIG.
That value is set as the torque set value T2. Next processing 70
In 2, the movement of the gripping claw 30 is started at the speed V2 and the torque set value T2 in the tightening direction.

In the next judgment 703, it is judged whether or not the drive torque of the spindle motor 4 has reached the torque set value T2. If the torque set value T2 has not been reached, the drive of the spindle motor 4 is continued. If the torque set value T2 has been reached, the clutch tooth position adjustment processing (FIG.
5). When the calling process 704 ends, the control for increasing the gripping force ends, and the process returns to the calling source. After the gripping force is changed, the chuck 15 is released, the clutch teeth 116 and 117 are engaged, and the next processing is started.

FIG. 15 shows a state in which the gripping force is increased in FIG.
It is a flowchart which shows the processing content of the clutch tooth position alignment process called by the calling process 704. In the process 711, the true current position of the grip claw 30 on the C axis is calculated. The true current position is a value obtained by subtracting the C-axis servo delay amount from the current C-axis coordinate value. Next, the process proceeds to step 712, where the clutch engagement position closest to the true current position is calculated. The clutch engagement position is determined by clutch teeth 116 and 11.
Reference numeral 7 denotes a position where meshing is possible. Next, the processing proceeds to processing 713, where the extremely low speed V is adjusted to the nearest clutch engagement position.
3. The movement of the gripping claw 30 is started without any torque limitation.
Next, it waits until the movement is completed in the judgment 714, and returns to the calling source when the movement is completed.

FIG. 16 is a flow chart showing an example of the control for reducing the gripping force in the gripping force change control. In the gripping force reduction control, first, the gripping force is reduced to near the minimum gripping force, and then the gripping force is increased to a desired change value along with the tightening gripping force calibration data Da. First, in a process 721, a drive torque in a loosening direction movement corresponding to a grip force that does not drop a workpiece by a predetermined amount smaller than a minimum grip force of hardware basic parameters (see FIG. 4) is set as a torque lower limit set value. You. The torque lower limit set value is stored in a predetermined storage area provided in the parameter memory 55.

In the next process 722, the speed V is set in the loosening direction.
4. The driving of the spindle motor 4 is started without torque limitation.
In the next determination 723, it is determined whether or not the drive torque of the spindle motor 4 has reached the torque lower limit set value. If the torque lower limit set value has not been reached, the drive of the spindle motor 4 is continued. If the torque lower limit set value has been reached, the process proceeds to step 724. In the process 724, the driving torque corresponding to the changed gripping force is obtained from the tightening gripping force calibration data Da shown in FIG. 5, and the value is set as the torque set value (torque limit value) T2.

In the next process 725, the speed V2 is set in the tightening direction.
, The driving of the spindle motor 4 is started. In the next determination 726, it is determined whether or not the drive torque of the spindle motor 4 has reached the torque set value T2. When the torque set value T2 has not been reached, the drive of the spindle motor 4 is continued, and when the torque set value T2 has been reached, the clutch tooth positioning process of FIG. When the calling process 727 ends, the control of the gripping force reduction ends, and the process returns to the calling source.

When the gripping force is reduced by such control, if only the driving torque of the loosening direction movement corresponding to the minimum gripping force is stored, the loosening gripping force calibration data Db is not required and the tightening gripping force calibration data is stored. The change control of the gripping force can be performed only by Da. Therefore, a parameter memory for storing the loose gripping force calibration data Db is not required, and the configuration of the NC device 50 is simplified, and the loosening gripping force calibration data Db
Is unnecessary, and the cost of the control device can be reduced.

FIG. 17 is a flowchart showing another example of the control for reducing the gripping force. In this control of gripping force reduction,
This is to relax the gripping force and reduce it to a desired change value along the gripping force calibration data Db. In the example of FIG.
After changing the gripping force, drive in the tightening direction to check the gripping state. First, in a process 731, a driving torque corresponding to the changed gripping force is obtained from the loosening gripping force calibration data Db,
That value is set as the torque set value.

In the next process 732, the speed V is set in the loosening direction.
4. The driving of the spindle motor 4 is started without torque limitation.
In the next judgment 733, it is judged whether or not the drive torque of the spindle motor 4 has reached the torque set value. If the torque set value has not been reached, the driving of the spindle motor 4 is continued. If the torque set value has been reached, the process proceeds to step 734. Processing 7
At 34, the drive torque corresponding to the changed gripping force is obtained from the tightening gripping force calibration data Da, and the value is set as the torque set value (torque limit value) T2.

In the next process 735, the speed V
2. The driving of the spindle motor 4 is started at the torque set value T2. In the next judgment 736, it is judged whether or not the drive torque of the spindle motor 4 has reached the torque set value T2. When the torque set value T2 has not been reached, the drive of the spindle motor 4 is continued.
Go to 7.

In the judgment 737, it is judged whether or not the spindle motor 4 has started to be driven in the tightening direction and then has rotated by a predetermined angle or more in the tightening direction. In this case, the main spindle motor 4 should not rotate in the C-axis direction.
At 9, an alarm signal is generated, and then the process returns to the calling source.
If it is determined in step 737 that the spindle motor 4 has not rotated by the predetermined amount or more, the calling process 738 calls the clutch tooth alignment process shown in FIG. When the calling process 738 is finished, the control for reducing the gripping force is finished, and the process returns to the calling source.

In the example shown in FIG. 17B, the driving in the tightening direction for checking the grip state after the change of the grip force is omitted.
In the first processing 771, the drive torque corresponding to the changed gripping force is obtained from the loosening gripping force calibration data Db, and the value is set as the torque set value T2. In the next process 772, the drive of the spindle motor 4 is started in the loosening direction without the speed V4 and the torque limitation. In the next determination 773, it is determined whether or not the drive torque of the spindle motor 4 has decreased from the value before the change and has reached the torque set value T2. If the torque set value T2 has not been reached, the driving of the spindle motor 4 is continued. If the torque set value T2 has been reached, the calling process 774 proceeds to FIG.
5 is called. Call processing 7
When 74 is completed, the control for reducing the gripping force is terminated, and the process returns to the calling source.

When the gripping force is reduced by such control, the torque set value corresponding to the changed gripping force is loosened, and the gripping force is directly obtained by the gripping force calibration data Db to change the gripping force. And the reliability of the value of the gripping force after the change is improved. Further, if the tightening direction drive is performed after the change of the gripping force, the gripping state can be confirmed, and the gripping can be reliably performed. If the driving in the tightening direction after changing the gripping force is omitted, the control can be simplified and the cost can be reduced.

FIG. 18 is a flowchart showing still another example of the control for reducing the gripping force. In this gripping force reduction control, the gripping force return angle data Dc, Dd, De shown in FIG.
Calculates the return angle for reducing the gripping force from the current gripping force to a desired change value, and rotates the spindle motor 4 in the loosening direction by the return angle. After changing the gripping force, drive in the tightening direction to check the gripping state.

First, in processing 741, a return angle corresponding to the changed gripping force with the current gripping force as an initial value is calculated from the gripping force return angle data Dc, Dd, De. The initial value of the grip force such as the grip force return angle data Dc can be accurately calculated by taking many initial values and measuring a number of relationship curves. When the current gripping force does not match the initial value of the gripping force return angle data Dc or the like, an interpolation operation is performed to calculate the return angle.

Next, in the process 742, the main shaft motor 4 is rotated in the loosening direction by the return angle calculated in the previous process without any speed limitation and the torque V4. In the process 743, the driving torque corresponding to the grip force after the change is the tightening grip force calibration data Da.
And the value is the torque set value (torque limit value)
It is set to T2. In the next process 744, the drive of the spindle motor 4 is started at the speed V2 in the tightening direction. Next decision 74
5, the driving torque of the spindle motor 4 is equal to the torque set value T2.
Is determined. If the torque set value T2 has not been reached, the drive of the spindle motor 4 is continued. If the torque set value T2 has been reached, the flow proceeds to decision 746.

In the judgment 746, it is judged whether or not the spindle motor 4 has rotated by a predetermined amount or more. If the rotation is equal to or more than the predetermined amount, it is determined that the normal gripping force cannot be changed.
At 8, an alarm signal is generated, and then the process returns to the calling source.
If the main spindle motor 4 is not rotating by a predetermined amount or more in the judgment 746, the clutch tooth positioning process of FIG. When the calling process 747 is finished, the control for reducing the gripping force is finished, and the process returns to the calling source.

When the gripping force is reduced by such control, the gripping force after the change can be stably changed even if the gripping force is considerably low. In other words, the grip force reduction change control based on the return angle has good reproducibility of the grip force after the change to a considerably low grip force region, and the grip force can be controlled to an accurate value. The processing 74 for confirming the grip state
3,744,748 and judgments 745,746 are preferably performed, but can be omitted.

FIG. 19 is a flowchart showing still another example of the control for reducing the gripping force. In this gripping force reduction control, first, loosen the gripping force to a reference gripping force as a reference, reduce the gripping force along the gripping force calibration data Db, and then grip the gripping force from the reference gripping force to a desired change value using the gripping force return angle data Dc or the like. The return angle for reducing the force is calculated, and the spindle motor 4 is rotated in the loosening direction by the return angle.
After changing the gripping force, drive in the tightening direction to check the gripping state.

First, in a process 751, a reference gripping force that is equal to or less than the current gripping force and greater than the gripping force after the change is selected, and a driving torque corresponding to the reference gripping force is obtained from the loosening gripping force calibration data Db. That value is set as the torque reference set value. The reference gripping force is selected from those actually measured as the initial value (value of the return angle 0) such as the gripping force return angle data Dc. In the next process 752, the speed V
4. The driving of the spindle motor 4 is started without torque limitation.
In the next determination 753, it is determined whether or not the drive torque of the spindle motor 4 has reached the torque reference set value. If the torque reference set value has not been reached, the drive of the spindle motor 4 is continued. If the torque reference set value has been reached, the process proceeds to step 754.

In the process 754, the return angle corresponding to the changed grip force is calculated from the grip force return angle data Dc and the like with the reference grip force as an initial value. Next, in process 755, the spindle motor 4 is rotated in the loosening direction by the return angle calculated at the speed V4. In the process 756, the driving torque corresponding to the changed gripping force is obtained from the tightening gripping force calibration data Da, and the value is set as the torque set value (torque limit value) T2. In the next process 757, the spindle motor 4
Starts driving. In the next judgment 758, the spindle motor 4
It is determined whether or not the driving torque has reached the torque set value T2. If the torque set value T2 has not been reached, the driving of the spindle motor 4 is continued, and if the torque set value T2 has been reached, the flow proceeds to judgment 759.

In the judgment 759, it is judged whether or not the spindle motor 4 has rotated a predetermined amount or more. If the rotation is equal to or more than the predetermined amount, it is determined that the normal gripping force cannot be changed.
At 1, an alarm signal is generated, and then the process returns to the caller.
If it is determined in step 759 that the spindle motor 4 has not rotated by the predetermined amount or more, the calling process 760 calls the clutch tooth alignment process shown in FIG. When the calling process 760 ends, the control for reducing the gripping force ends, and the process returns to the calling source.

If the gripping force is reduced by such control, the gripping force after the change can be changed stably even if the gripping force is considerably low. In other words, the grip force reduction change control based on the return angle has good reproducibility of the grip force after the change to a considerably low grip force region, and the grip force can be controlled to an accurate value. In addition, the gripping force return angle data Dc and the like need only be actually measured for one or several types of relationship curves with the reference gripping force as an initial value, and the actual measurement and setting of the gripping force return angle data Dc and the like are simplified. The cost of the control device can be reduced. Processing 7 for confirming the grip state
56, 757, 761 and judgments 758, 759 are preferably performed, but can be omitted.

A set value selection change program 544 as a set value selection change means is a process in which a predetermined command is programmed in the NC machining program, and when the command is executed, chucking data is selected or changed. Do. An instruction to select a set of chucking data (eg,
When “G10 L130 Pnn” comes, the nn-th set of chucking data stored in the chucking data memory 57 is selected. Also, a command to change the chucking data of a predetermined set of chucking data (for example, “G10 L131 Pnn Qmm Rd
When “d”) comes, the mm-th chucking data of the nn-th chucking data set is changed to dd and stored.

According to FIGS. 20 and 21, selection of a set of chucking data (parameter group No.) from the NC machining program and change of data such as gripping force are described below.
This will be described in more detail. Selection of a set of chucking data from the NC machining program is performed by a command shown in FIG. Here, “nn” of “Pnn” is the number of the set of chucking data.

This will be described in detail with reference to a program example shown in FIG. However, the part on the left side from the dotted line is a program, and the part on the right side from the dotted line is a comment. In the program for the workpiece A (O2000), since the number 10 of the set of chucking data is selected, the gripping force 5000
Chucking data such as kgf and a grip diameter of 100.0 mm is specified. Chuck clamp command (for example, M6
8) At the time of execution, the workpiece A is gripped according to the chucking data. FIG. 20C shows the parameter group No. The content of each data of the set of ten chucking data is shown.

The program for the work B (O220
In (0), since the number 12 of the set of chucking data is selected, the gripping force is 1000 kgf and the gripping diameter is 82.0 m.
When the chucking data such as m is specified and the chuck clamp command (for example, M68) is executed, the workpiece B is gripped according to the chucking data. FIG. 20 (d)
The parameter group No. 12 shows the contents of each data of a set of twelve chucking data.

Also, when performing primary processing (front processing), secondary processing (back processing), etc. of the same workpiece continuously,
By selecting such a set of chucking data, it is possible to select an optimum condition for gripping the workpiece. In addition, at the time of rough cutting and finish cutting, a workpiece can be gripped under optimal gripping conditions by selecting an optimal set of chucking data for each. That is, the workpiece can be gripped with a strong gripping force during rough cutting, and with a light gripping force that does not deform the workpiece during finish cutting.

The change of the chucking data from the NC machining program is performed by a command shown in FIG. Here, “nn” of “Pnn” is the number of the set of chucking data, “mm” of “Qmm” is the data number, and “dd” of “Rdd” is the changed data. In the data number “mm”, “1” indicates a gripping force, “2” indicates a gripping diameter, “3” indicates a shift point, “4” indicates an evacuation point, and “5” indicates an error detection level. Each data can be changed by specifying the number. FIG. 21C shows the correspondence between data numbers and data types.

A further description will be given with reference to FIG.
"G10 L131 P10 Q1R2000 .;"
Is a command to change the gripping force data of the chucking data set number 10 to 2000 kgf. The following directive:
The data of the save point of the same set number 10 is changed to 108 mm. In this manner, the chucking data can be used while being sequentially changed. That is, if at least one set of chucking data is provided in the chucking data memory 57, it is possible to hold all types of workpieces.

Further, by changing the gripping force of the chucking data, it is possible to change the gripping force while holding the workpiece. First, "G10 L131 P10 Q1 R2500 .;" in the NC machining program
As described above, the gripping force of the currently used chucking data is changed. Or, "G10 L130 P1
1; ", other chucking data having different gripping forces may be selected. Further, by setting “M67;”, the change of the gripping force as shown in FIGS. 14 to 19 is controlled. "M67" performs grip force change control NC
Directive. Depending on whether or not the gripping force after the change is greater than the current gripping force, either control of increasing the gripping force or decreasing the gripping force is selected. Here, the NC command for controlling the change of the gripping force is “M67”, but may be another code.

As described above, since the chuck capable of moving the gripping claws in a wide range can be controlled while selecting and changing the chucking data by the NC processing program, continuous processing of a plurality of types of workpieces can be performed. Will be possible. In addition, since continuous machining can be performed by unmanned operation of the machine tool, productivity can be improved and automation can be achieved. Further, since the gripping force can be changed while holding the workpiece, the working efficiency is improved and the processing accuracy is improved.

As described above, in the electric chuck in which the moving stroke of the gripper is large and applicable to a wide range of workpieces, the speed of the gripper is switched between high and low in accordance with the position of the gripper. In addition, the gripping time can be reduced despite the large stroke. Further, in the case where the opening and closing drive is performed by the main shaft motor, the high-speed and low-speed of the gripping claws can be performed by the rapid feed of the C-axis feed and the cutting feed, thereby simplifying the control. Furthermore, since the starting position (evacuation point) of the gripping claw and the gripping diameter can be set to arbitrary values, the electric chuck capable of gripping a workpiece having a wide moving stroke with a large moving stroke of the gripping claw. Even in this case, the moving stroke in the actual gripping operation can be reduced to a necessary minimum amount, and the gripping and releasing operation time can be shortened.

When the diameter of the workpiece is out of the allowable error range, an error signal is output, or a gripping signal for confirming gripping of the workpiece is output by combining the driving torque of the drive motor and the gripping claw position. can do. Further, other alarm signals can be output by combining the driving torque of the driving motor and the grip claw position. Thereby, the reliability and safety of the chucking operation are improved.

In the above embodiment, the opening and closing drive of the gripping claws is performed by the spindle motor.
The opening and closing drive of the gripping claws may be performed by a dedicated motor different from the spindle motor. Further, the chuck is provided on the rotatable main shaft. However, the chuck may be provided on a frame such as a table of a machine tool such as a machining center, or on a mounting member on the frame.

[0143]

Since the present invention is configured as described above, it has the following effects.

Since the gripping force of the gripping claw is changed according to the relationship data indicating the relationship between the gripping force and the driving torque or the rotation amount of the drive motor, the gripping force is changed without removing the workpiece while holding the workpiece. And work efficiency is improved. Also, since the workpiece is not removed once, the gripping position of the workpiece does not change, and the common workpiece coordinates can be used for the primary processing and the secondary processing, resulting in high-efficiency and high-precision processing Becomes possible.

After the processing by the first gripping force is completed, the second gripping force is changed to a second gripping force smaller than the first gripping force. Therefore, the workpiece is firmly gripped with a high gripping force and rough processing is performed. Then, the gripping force is changed to a low gripping force, and a high-accuracy finishing process can be performed without causing distortion of the workpiece due to the gripping force.

After the drive torque of the drive motor is reduced to the torque lower limit set value corresponding to the grip force smaller than the second grip force, the drive torque of the drive motor is controlled in accordance with the tightening grip force calibration data, and the second drive torque is controlled. Since the workpiece is gripped with the gripping force of, the change control of the gripping force is possible only with the tightening gripping force calibration data without the need for loosening gripping force calibration data, and the parameter memory for storing the loosening gripping force calibration data is This eliminates the need to simplify the configuration of the control device, and eliminates the need to store the loose gripping force calibration data, thereby reducing the cost of the control device.

The related gripping force calibration data and the loosening gripping force calibration data are included, and the reduction control is performed from the first gripping force to the second gripping force along the loosening gripping force calibration data. Accordingly, the time required for changing the gripping force is reduced, and the reliability of the gripping force value after the change is improved.

Since the drive motor is controlled to return from the first gripping force to the gripping force return amount data in accordance with the gripping force return amount data, the workpiece is gripped with the second gripping force. The change control can be stably performed, and the grip force in the low grip force region can be controlled to an accurate value with good reproducibility.

The reference gripping force is set, loosened from the first gripping force to the reference gripping force, and reduced according to the gripping force calibration data.
Since the reduction control is performed according to the gripping force return data from the reference gripping force to the second gripping force, even if the changed gripping force is considerably low, the change control can be stably performed, and the low gripping force area can be controlled. Can be controlled to an accurate value with good reproducibility. Further, the gripping force return angle data may be obtained by actually measuring only one type or several types of relationship curves having the reference gripping force as an initial value.
The setting operation can be simplified, and the cost of the control device can be reduced.

After the workpiece is gripped by the second gripping force, the drive motor is driven in the gripping direction to check the gripping state. Therefore, when the normal gripping force cannot be changed,
By outputting an alarm signal or the like, damage to the workpiece or the machine tool can be prevented.

Since the change of the gripping force can be executed by the command of the NC machining program, the continuous machining by the unmanned operation of the machine tool becomes possible, thereby improving the productivity and automation. Further, since the gripping force can be changed while holding the workpiece, the working efficiency is improved and the processing accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a chuck of an NC lathe to which the present invention is applied.

FIG. 2 is a block diagram illustrating a configuration of an NC device.

FIG. 3 is a diagram illustrating a configuration of an operation panel of the chuck.

FIG. 4 is a diagram illustrating a chuck maintenance screen displayed on a display unit of the NC device.

FIG. 5 is a diagram illustrating a gripping force calibration curve showing a relationship between a driving torque and a gripping force.

FIG. 6 is a diagram illustrating a grip force return angle relationship curve indicating a relationship between a return angle and a grip force;

FIG. 7 is a view showing a chuck setting screen displayed on a display unit.

FIG. 8 is a diagram illustrating control of the position and speed of a gripping claw when the chuck is normally opened and closed.

FIG. 9 is a diagram illustrating control of the position and speed of a gripping claw during setup opening and closing of the chuck.

FIG. 10 is a flowchart showing control of normal gripping of the chuck.

FIG. 11 is a flowchart illustrating control of normal release of the chuck.

FIG. 12 is a flowchart showing control of setup chucking of a chuck.

FIG. 13 is a flowchart showing control of setup release of the chuck.

FIG. 14 is a flowchart illustrating control for increasing a gripping force.

FIG. 15 is a flowchart illustrating control of clutch tooth alignment.

FIG. 16 is a flowchart illustrating an example of control of gripping force reduction.

FIG. 17 is a flowchart illustrating another example of gripping force reduction control.

FIG. 18 is a flowchart illustrating another example of gripping force reduction control.

FIG. 19 is a flowchart illustrating another example of gripping force reduction control.

FIG. 20 is a diagram illustrating an example of an NC machining program for selecting a set of chucking data;

FIG. 21 is a diagram illustrating N changing chucking data.
It is a figure showing an example of a C processing program.

[Explanation of symbols]

 Reference Signs List 2 ... Spindle 4 ... Spindle motor 6 ... X-axis motor 7 ... Z-axis motor 10 ... Spindle end 12 ... Face plate 15 ... Chuck 19 ... Scroll groove 20 ... Main body 21 ... First member 22 ... Second member 26 ... Master jaw 28 ... scroll teeth 30 ... gripping claws 41 ... positioning holes 45 ... fixing pins 50 ... NC device 82 ... drive gear fixing plate 85 ... drive gear main body 86 ... drive gear 90 ... scroll support cylinder 96 ... scroll 97 ... internal gear 100 ... intermediate Gear 101: Air supply path 110: Cylinder chamber 111: Cylinder cylinder 112: Piston 113: Clutch plate 114: Guide pin 115: Coil spring 116: Clutch teeth 117: Clutch teeth 510: Operation panel 511: Mode changeover switch 512: Internal / external tightening Changeover switch 513 ... Grip release switch 514 ... Setup opening / closing switch Switch

Claims (18)

[Claims] An electric motor for gripping a workpiece by opening and closing a gripping claw (30) of a chuck (15) supported on a frame provided on a body of a machine tool by a drive motor (4) capable of controlling a driving torque. A method for controlling a chuck, comprising: a step of inputting a set value of a gripping force that is a force of the gripping claw (30) gripping a workpiece; and the driving torque or rotation of the gripping force and the drive motor (4). A procedure for storing relationship data (Da to De) indicating a relationship with an amount, controlling the drive motor (4) according to the relationship data (Da to De), and performing first gripping by the gripping claws (30). A procedure for gripping the workpiece with force, and the relationship data (Da to D
e) controlling the drive motor (4) in accordance with e) and changing the gripping force of the gripping claws (30) to a second gripping force different from the first gripping force. Control method. 2. The method of controlling an electric chuck according to claim 1, wherein the second gripping force is smaller than the first gripping force. 3. The control method for an electric chuck according to claim 2, wherein the relational data includes the gripping force and the driving motor (4) when the moving direction of the gripping claw (30) is the gripping direction. )
Including a tightening gripping force calibration data (Da) indicating a relationship with the driving torque, and storing a torque lower limit set value that is a driving torque corresponding to a gripping force smaller than the second gripping force. The grip force changing step includes controlling the drive torque of the drive motor (4) according to the tightening grip force calibration data (Da) after reducing the drive torque of the drive motor (4) to the torque lower limit set value. And the gripping claws (3
0) A method for controlling an electric chuck, which grips a workpiece with the second gripping force. 4. The control method for an electric chuck according to claim 1, wherein the relation data is that the gripping is performed when a moving direction of the gripping claw is a gripping direction. Force and the drive motor (4)
And the gripping force calibration data (Da) indicating the relationship with the driving torque, the gripping force when the moving direction of the gripping claw (30) is the release direction, and the driving torque of the drive motor (4). Gripping force calibration data (D
b) A method for controlling an electric chuck, comprising: 5. The method for controlling an electric chuck according to claim 4, wherein the gripping force changing step includes the loosening gripping force calibration data (D
(b) controlling the drive torque of the drive motor (4) and gripping the workpiece with the second gripping force by the gripping claws (30); 6. The control method for an electric chuck according to claim 2, wherein the drive motor (4) is capable of controlling a rotation angle position, and the relation data is the drive motor (4). Includes grip force return amount data (Dc to De) indicating a relationship between a return amount, which is an amount of rotation in a release direction from a state where the workpiece is gripped by the grip claws (30), and the grip force. The change procedure is based on the gripping force return amount data (Dc
To De) to control the drive motor (4) so as to grip the workpiece with the second gripping force.
0) is a method of controlling the electric chuck, which is for returning the electric chuck to the release direction. 7. The electric chuck control method according to claim 4, wherein the drive motor (4) is capable of controlling a rotation angle position, and the relation data is the drive motor (4). Includes gripping force return amount data (Dc to De) indicating a relationship between a return amount, which is an amount of rotation in a release direction from a state where the workpiece is gripped by the gripping claw (30), and the gripping force; Setting a reference gripping force that is greater than the gripping force of the first gripping force and less than or equal to the first gripping force. The gripping force changing procedure includes the loosening gripping force calibration data (D
b) changing the drive torque of the drive motor (4) to a value corresponding to the reference gripping force, and controlling the drive motor (4) in accordance with the gripping force return amount data (Dc to De) to A control method for an electric chuck, wherein the gripper (30) is returned to a release direction so as to grip a workpiece with a second gripping force. 8. The method for controlling an electric chuck according to claim 5, wherein the step of changing the gripping force includes the step of gripping the workpiece with the second gripping force, and then adjusting the driving force. A method for controlling an electric chuck, including a step of driving a motor (4) in a gripping direction to check a gripping state. 9. The control method for an electric chuck according to claim 1, wherein the gripping force changing step is executed by a command of an NC machining program. Method. 10. A control device which is supported by a frame provided on a body of a machine tool and controls a chuck (15) for opening and closing a gripper (30) to grip a workpiece. A drive motor (4) that drives the gripping claw (30) to open and close to control a gripping force that is a force with which the gripping claw (30) grips a workpiece; and an input for inputting a set value of the gripping force. Means (59); means (55) for storing relation data (Da to De) indicating a relation between the gripping force and the driving torque or rotation amount of the driving motor (4); and the relation data (Da to De), the driving motor (4) is controlled, the workpiece is gripped by the gripping claw (30) with a first gripping force, and the workpiece is gripped while the gripping claw (30) is held in accordance with the relational data (Da to De). Control of the drive motor (4) And a gripping claw control means (50) for changing a gripping force of said gripping claw (30) to a second gripping force different from said first gripping force. 11. The control device for an electric chuck according to claim 10, wherein the second gripping force is smaller than the first gripping force. 12. The control device for an electric chuck according to claim 11, wherein the relational data includes the gripping force and the drive motor (4) when the moving direction of the gripping claw (30) is the gripping direction. )
Means (55) for storing a torque lower limit set value that is a driving torque corresponding to a gripping force smaller than the second gripping force, including tightening gripping force calibration data (Da) indicating a relationship with the driving torque. The gripping claw control means (50) includes the drive motor (4).
After the driving torque of the driving motor (4) is reduced to the torque lower limit set value, the driving torque of the driving motor (4) is controlled in accordance with the tightening gripping force calibration data (Da), and the gripping claw (30) controls the second driving torque. An electric chuck control device for gripping a workpiece with a gripping force. 13. The control device for an electric chuck according to claim 10, wherein the relational data is obtained when the moving direction of the gripping claw is a gripping direction. Force and the drive motor (4)
And the gripping force calibration data (Da) indicating the relationship with the driving torque, the gripping force when the moving direction of the gripping claw (30) is the release direction, and the driving torque of the drive motor (4). Gripping force calibration data (D
b) A control device for an electric chuck, comprising: 14. The control device for an electric chuck according to claim 13, wherein the gripping claw control means (50) controls the driving torque of the driving motor (4) according to the loose gripping force calibration data (Db). A control device for controlling an electric chuck, wherein the workpiece is gripped by the gripping claw (30) with the second gripping force. 15. The control device for an electric chuck according to claim 11, wherein the drive motor (4) is capable of controlling a rotation angle position, and the relation data is the drive motor (4). Includes grip force return amount data (Dc to De) indicating a relationship between a return amount, which is an amount of rotation in a release direction from a state in which the workpiece is gripped by the grip claws (30), and the grip force, The gripping claw control means (50) controls the drive motor (4) in accordance with the gripping force return amount data (Dc to De) to grip the workpiece with the second gripping force. 30) A control device for an electric chuck for returning the electric chuck to the release direction. 16. The control device for an electric chuck according to claim 13, wherein said drive motor (4) is capable of controlling a rotation angle position, and said relation data is said drive motor (4). Includes grip force return amount data (Dc to De) indicating a relationship between a return amount, which is an amount of rotation in a release direction from a state in which the workpiece is gripped by the grip claws (30), and the grip force, The gripping claw control means (50) sets a reference gripping force that is greater than the second gripping force and equal to or less than the first gripping force, and controls the drive motor (4) according to the loosening gripping force calibration data (Db). After changing the driving torque to a value corresponding to the reference gripping force, the gripping force return amount data (Dc to Dc
e) controlling the drive motor (4) according to the second
Gripping claw (30) so as to grip a workpiece with a gripping force of
Control device for returning the electric chuck to the release direction. 17. The control device for an electric chuck according to claim 14, wherein the gripping claw control means (50) grips the workpiece with the second gripping force. And an electric chuck control device for driving the drive motor (4) in a gripping direction to check a gripping state. 18. The control device for an electric chuck according to claim 10, wherein the gripping claw control means (50) changes the gripping force according to an instruction of an NC machining program. Control device for electric chuck.