JP2001079703A - Method and device for controlling electric chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time required for a grip by switching the relative data between the driving torque and the gripping force according to the gripping speed when the set value of the holding force is in a low gripping force region or in a high gripping force region in the chuck of a machine tool opened or closed by a drive motor. SOLUTION: When a work is to be gripped by a chuck 15, an upper shaft 2 is positioned and stopped at a prescribed angular position by the main shaft index instruction from an NC device. A securing pin 45 is inserted into a positioning hole 41, and a piston 112 is driven by the pressurized air fed through the center of the securing pin 45 to release the engagement between clutch teeth 116, 117. The main shaft 2 is rotated by a main shaft motor 4, a scroll 96 is rotated via a gear reduction mechanism to open or close gripping pawls 30. The gripping speed is switched according to the set value of the gripping force, and a plurality of relative data indicating the relation between the gripping force and the driving torque of the drive motor are switched according to the gripping speed to control the gripping force.

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 which drives a chuck of a machine tool to be opened and closed by a drive motor, and more particularly, to an area for controlling a gripping force of a workpiece from a low gripping force area to a high gripping force area. The present invention relates to a method and an apparatus for controlling an electric chuck that can accurately control the electric chuck.

[0002]

2. Description of the Related Art A chuck for holding 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]

In the above-described apparatus in which the opening and closing of the gripping claws are driven by a servomotor, the opening position of the gripping claws 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.

In view of the above, the present invention provides an electric chuck in which a chuck of a machine tool is driven to open and close by a drive motor, whereby the gripping force of a workpiece can be accurately controlled from a low gripping force region to a high gripping force region. An object of the present invention is to provide an electric chuck control method and apparatus capable of shortening a workpiece holding time.

[0006]

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 of controlling an electric chuck that grips a workpiece by opening and closing by a simple drive motor, comprising: a step of inputting a set value of a gripping force that is a force by which the gripper grips the workpiece; A procedure for storing a plurality of relationship data indicating a relationship between the gripping force and the drive torque of the drive motor in accordance with a moving speed, and a procedure for storing the plurality of relationship data in accordance with a set value of the gripping force. And making the related data valid, and controlling the gripping force.

Further, according to a method of controlling an electric chuck of the present invention, a workpiece is gripped by opening and closing a gripping claw of a chuck supported on a frame provided on a body of a machine tool by a drive motor capable of controlling drive torque. A method for controlling an electric chuck, comprising: a step of inputting a set value of a gripping force, which is a force by which the gripping claw grips a workpiece; and a plurality of steps indicating a relationship between the gripping force and the drive torque of the drive motor. Storing a plurality of pieces of relational data, wherein a plurality of pieces of relational data are stored at intervals in which a relation between the gripping force in one piece of relational data and the driving torque of the drive motor is smaller than an interval in other relational data; One of the plurality of relational data is made valid according to the set value of the force, and the relational data having a narrow interval in an area where high-precision grip force control is required. Those having a procedure for controlling the gripping force using.

In the above-mentioned electric chuck control method, the plurality of relational data may include a low gripping force indicating a relationship between the gripping force and the driving torque when the gripping claw moves at a first speed. Force calibration data and at least two data of high gripping force calibration data indicating a relationship between the gripping force and the driving torque when the moving speed of the gripping claw is a second speed greater than the first speed. Including, the control procedure, in accordance with the set value of the gripping force, the control speed of the gripping force according to the low gripping force calibration data with the moving speed of the gripping claw as the first speed, or It is preferable that the control is performed by switching whether to control the gripping force in accordance with the high gripping force calibration data while setting the moving speed of the gripping claw to the second speed.

In the above-described electric chuck control method, a step of storing a switching gripping force, which is a value of the gripping force for switching the control of the gripping claw, is stored. When the set value is smaller than the switching gripping force, the gripping force is controlled according to the low gripping force calibration data while the moving speed of the gripping claw is set to the first speed, and the set value of the gripping force is changed to the switching speed. When the gripping force is equal to or more than the gripping force, the gripping force is preferably controlled according to the high gripping force calibration data while setting the moving speed of the gripping claw to the second speed.

In the above-described method for controlling the electric chuck, the method may further include stopping the movement of the gripping claw when the driving torque of the driving motor reaches a value corresponding to the gripping force set value. preferable.

In the above control method of the electric chuck, it is preferable that the chuck is provided on a spindle rotatably supported on a headstock of a machine tool.

In the above-described method for controlling an electric chuck, the drive motor rotates and positions the spindle around a spindle axis, and rotates the main body of the chuck with respect to the machine body of the machine tool. The procedure to make the fixed state impossible, and the main body part in the fixed state,
Controlling the drive motor to open and close the gripping claws.

[0013] 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 an electric chuck that controls a chuck that grips a workpiece by opening and closing gripping claws, the gripping claw of the chuck being driven to open and close, and a gripping force that is a force of the gripping nail gripping a workpiece. A controllable driving motor, input means for inputting the set value of the gripping force, and a plurality of the plurality of moving speeds of the gripping claws, each showing a relationship between the gripping force and a driving torque of the driving motor. Means for storing relational data, and gripping claw control for controlling the gripping force of the gripping claw such that one of the plurality of relational data becomes valid in accordance with the set value of the gripping force. Means.

Further, the electric chuck control device of the present invention is supported by a frame provided on a body of a machine tool,
A control device for an electric chuck that controls a chuck that grips a workpiece by opening and closing gripping claws, the gripping claw of the chuck being driven to open and close, and a gripping force that is a force of the gripping nail gripping a workpiece. A controllable drive motor, input means for inputting the set value of the gripping force, and a plurality of relationship data indicating a relationship between the gripping force and the drive torque of the drive motor, wherein Means for storing a plurality of relationship data in which an interval for obtaining a relationship between the gripping force and the drive torque of the drive motor is smaller than an interval in other relationship data, and the plurality of relationship data corresponding to a set value of the gripping force. Gripping claw control means for controlling one gripping force of the gripping claw by using the relational data having a narrow interval in an area where high-precision gripping force control is required, so that one of the relational data is valid; And it has a door.

In the above-described electric chuck control device, the means for storing the plurality of relational data may include a relation between the gripping force and the driving torque when the moving speed of the gripping claw is a first speed. Means for storing low grip force calibration data indicating a high grip force indicating a relationship between the grip force and the drive torque when the moving speed of the grip claw is a second speed faster than the first speed. The gripping claw control means includes at least two means for storing calibration data, wherein the gripping claw control means sets the moving speed of the gripping claw to the first speed and controls the gripping force according to the low gripping force calibration data. Or controlling the gripping force of the gripping claws by switching between setting the moving speed of the gripping claws to the second speed and controlling the gripping force in accordance with the high gripping force calibration data. Door is preferable.

In the above-described electric chuck control device, there is provided means for storing a switching gripping force which is a value of the gripping force for switching the control of the gripping claw. If the set value of the force is smaller than the switching gripping force, the driving speed is controlled according to the low gripping force calibration data while setting the moving speed of the gripping claw to the first speed, and the set value of the gripping force is When the switching gripping force is equal to or more than the switching gripping force, the driving speed is preferably controlled according to the high gripping force calibration data while setting the moving speed of the gripping claw to the second speed.

In the above-described control device for an electric chuck, the gripping claw control means may control the movement of the gripping claw when the driving torque of the drive motor reaches a value corresponding to the gripping force set value. Preferably, it is stopped.

In the above-described electric chuck control device, it is preferable that the chuck is provided on a spindle rotatably supported by a headstock of a machine tool.

In the above-described electric chuck control device, a fixed state in which the main body of the chuck cannot be rotated with respect to the machine body of the machine tool, and the main body portion can be rotated with respect to the machine body of the machine tool. The drive motor is for rotating and positioning the spindle around a spindle axis, and the gripping claw control means is provided with the chuck rotation fix switching means. To set the main body in the fixed state, and control the drive motor to open and close the gripping claws.

In the electric chuck control device, the chuck rotation fixing switching means enables relative rotation between the main body and the main spindle in the fixed state, and the main body and the main spindle in the released state. It is preferable that relative rotation with respect to is not possible.

[0021]

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 driven to rotate 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 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.

Behind the clutch plate 113, a coil spring 115 is disposed at an equiangular position. 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 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 obtained by 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 in the relationship 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 a table in a low gripping force calibration data area 552 and a high gripping force calibration data area 553 described later. It is stored as Then, the setting value selection change program 544 is
This is a program for selecting a set of chucking data stored in the chucking data memory 57 or changing the chucking data according to a command of a 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. In the parameter memory 55, storage areas of a chuck basic parameter area 551, a low grip force calibration data area 552, a high grip force calibration data area 553, and a switching grip force data area 554 are set.

The chuck basic parameter area 551 is a storage area for storing various chuck-specific chuck basic parameters 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 low gripping force calibration data area 552 and the high gripping force calibration data area 553 are storage areas for storing data for calculating the relationship between the torque limit value of the spindle motor 4 and the gripping force of the chuck 15 of the chuck 15. .

When the gripping force is relatively small (low gripping force), the rotation speed of the spindle motor 4 is reduced to a low speed (for example, 5 rotations /
As a minute), the gripping force of a small area can be accurately controlled. When the gripping force is relatively large (high gripping force), the rotation speed of the spindle motor 4 is set to a higher speed (for example, 30 rotations / minute) than when the gripping force is low, so that the gripping time can be reduced. For this reason, the low grip force calibration data Da (see FIG. 5) in the low grip force region and the high grip force calibration data Db (see FIG. 5) in the high grip force region are respectively included in the low grip force calibration data region 552 and the low grip force calibration data region 552. It is stored in the high grip force calibration data area 553.

The switching grip force is a boundary value of the grip force for switching the control of the grip force between the low grip force region and the high grip force region. The switching gripping force is stored in the switching gripping force data area 554. If the set value of the gripping force is smaller than the switching gripping force, the driving torque and the gripping force are converted by the low gripping force calibration data Da as a low gripping force area, and the gripping operation is performed with the rotation speed of the spindle motor 4 being low. . If the set value of the gripping force is equal to or greater than the switching gripping force, the driving torque and the gripping force are converted by the high gripping force calibration data Db as a high gripping force area, and the gripping operation is performed with the rotation speed of the spindle motor 4 being high. .

Further, an NC machining program memory 56 and a chucking data memory 57 are connected to the CPU 51 via a bus 52. In the NC machining program memory 56, the workpiece is released from the chuck 15, the workpiece is gripped by the chuck 15, and the tool rest (not shown) and the headstock are relatively Z-axis (parallel to the spindle axis). NC machining programs for performing movement control in the directions of the X axis (coordinate axes orthogonal to the Z axis) and the X axis (coordinate axes orthogonal to the Z axis). The chucking data memory 57 is a memory for storing various data displayed on the chuck setting screen (see FIG. 6) of the display means 58. The chucking data is
This 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 the 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 close 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 view 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. Pressing the "setting" key of the function key from this screen displays the chuck setting screen of FIG. 6, and pressing the "calibration" key of the function key from this screen causes the chucking screen of FIG.
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 in-chuck reduction ratio is a reduction ratio of 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 loosening operation of the gripping claw 30. T1 is entered as a percentage of the maximum torque. The C-axis command speed V1 is the C-axis movement speed at the time of high-speed movement of the gripping claw 30, and is, for example, the C-axis rapid traverse speed.

The C-axis command speed V2 is the C-axis moving speed during the gripping operation of the gripping claws 30. As the C-axis command speed V2, a speed V2a in a low gripping force region where the set gripping force is smaller than the switching gripping force, and a speed V2b in a high gripping force region where the set gripping force is equal to or greater than the switching gripping force are set. . Speed V2a
The speed V2b is higher than the speed V2b (for example, when the speed V2a is 5).
(The speed V2b is set to 30 rotations / minute with respect to the rotation / minute). 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). The unit of V1, V2, V3 is rotation / minute.

FIG. 5 is a diagram showing a grip force calibration screen displayed on the display means 58 of the NC device 50. This is a screen for setting gripping force calibration data for converting the driving torque of the spindle motor 4 and the gripping force. This screen is displayed by pressing the "calibration" key of the function key from the chuck maintenance screen of FIG. Low grip force calibration data Da indicating the relationship between the drive torque of the spindle motor 4 and the grip force at the C-axis command speed V2a, and high grip indicating the relationship between the drive torque of the spindle motor 4 and the grip force at the C-axis command speed V2b. The force calibration data Db is displayed. The low grip force calibration data Da is stored in the low grip force calibration data area 552 in the parameter memory 55, and the high grip force calibration data Db
Are stored in the high gripping force calibration data area 553.

The low grip force calibration data Da and the high grip force calibration data Db are obtained by actually measuring and storing the relationship between the torque limit value (expressed as a percentage of the maximum torque) of the spindle motor 4 and the grip force of the chuck 15. It is. These data are displayed in numerical table format on the left side of the screen. The numerical values of the torque limit and the gripping force can be rewritten based on the actually measured values. On the right side of the screen, low grip force calibration data Da and high grip force calibration data Db are displayed in a graph format. The gripping force calibration data is obtained by narrowing the interval for obtaining the calibration data (interval of the driving torque for actually measuring the gripping force) for the low gripping force calibration data Da compared to the high gripping force calibration data Db, Is desirably set. By doing so, the accuracy and reliability of the low gripping force calibration data Da are improved, and the workpiece can be gripped with a more accurate gripping force.

The driving torque and the gripping force are converted based on the low gripping force calibration data Da and the high gripping force calibration data Db. The gripping force for the driving torque intermediate between the measured value and the measured value is interpolated assuming that it is on a straight line. Whether to perform conversion based on the low grip force calibration data Da or the high grip force calibration data Db is automatically switched according to the magnitude relationship between the set value of the grip force and the switching grip force. The switching grip force is a boundary value of the grip force for switching the control of the grip force in the low grip force region and the high grip force region. By inputting a value in the "switching grip force" input field at the bottom left of the screen,
The set value of the switching gripping force can be changed. In FIG. 5, the switching gripping force is set to 2000 kgf.

If the set value of the gripping force is smaller than the switching gripping force, the driving torque and the gripping force are converted based on the low gripping force calibration data Da, and the rotation speed of the spindle motor 4 is reduced to the speed V2.
The gripping operation is performed as a. If the set value of the gripping force is equal to or greater than the switching gripping force, the driving torque and the gripping force are converted based on the high gripping force calibration data Db, and the gripping operation is performed with the rotation speed of the spindle motor 4 as the speed V2b.

When the low grip force calibration data Da, the high grip force calibration data Db, and the switching grip force are set on this screen and the "save" key of the function key is pressed, these data are respectively stored in the low grip force calibration data area 552. Are stored in the high grip force calibration data area 553 and the switching grip force data area 554.
The "speed" key of the function key is used to manually set the gripping speed (C-axis command speed V2) to high speed (V2b) or low speed (V2a) in order to actually measure the relationship between the driving torque and the gripping force. . Each time the "speed" key is pressed, the gripping speed switches between "high" and "low". Pressing the "return" key of the function key returns to the chuck maintenance screen of FIG.

Although the driving torque and the gripping force are stored here in the form of a numerical table based on the actually measured values, the relational expression between the driving torque and the gripping force may be stored as a mathematical expression. The low gripping force calibration data Da and the high gripping force calibration data Db are chuck-specific parameters set by the machine tool maker. Normally, the user does not change this, but it can.

FIG. 6 is a diagram showing a chuck setting screen displayed on the display means 58 of the NC device 50. 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. 6, 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. 6, 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. 7 is a diagram showing control of the position and speed of the gripping claws 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. 7A shows a 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.

The value of the speed V2 is automatically set to the speed V2a or V2b according to the magnitude relationship between the set value of the gripping force and the switching gripping force as described above. If the set value of the gripping force is smaller than the switching gripping force, the speed V2 is changed to the speed V2.
The gripping operation is performed as a, and the driving torque and the gripping force are converted based on the low gripping force calibration data Da. If the set value of the gripping force is equal to or greater than the switching gripping force, the gripping operation is performed with the speed V2 set to the speed V2b, and the driving torque and the gripping force are converted based on the high gripping force calibration data Db.

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 stop position of the main shaft 2 (the grip point of the grip claw 30) must be a position at each predetermined angle at which the clutch teeth 116 and 117 can mesh. Therefore, from the stop point due to the torque limit value T2,
Control is performed so that the gripping claws 30 move at the extremely low speed V3 to the gripping points at these predetermined angles and stop at the nearest gripping point.

FIG. 7B shows an example in which an error occurs in the gripping of the outer fastening in the 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. 7C shows a case where the outer fastening is released in the 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. 8 is a diagram showing the control of the position and speed of the gripping claw 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. 8 (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. As described above, the value of the speed V2 is automatically set to the speed V2a according to the magnitude relationship between the set value of the gripping force and the switching gripping force.
Alternatively, the speed is set to the speed V2b. Gripping claw 30
Grips the workpiece, and stops moving when the drive torque of the spindle motor 4 reaches the torque limit value T2 corresponding to the gripping force. The grip claw 30 moves at an extremely low speed V3 from a stop point by the torque limit value T2 to a grip point at each predetermined angle,
The control to stop at the nearest gripping point is the same as in FIG.

FIG. 8 (b) shows the gripper 3
0 is simply moved in the closing direction. The gripper 30 moves from the current position in the closing direction at a low speed V2 by pressing the foot switch 501, and stops at the position where the foot switch 501 is released. The value of the speed V2 is set to the speed V2b. FIG. 8 (c) shows a case of inner tightening grip in setup opening and closing. This is the same as the speed control of FIG. 8A, except that the moving direction is different. FIG. 8D shows a case where the grip claw 30 is simply moved in the opening direction in the setup opening and closing. This is also the same as the speed control in FIG. 8B except that the moving direction is different.

FIG. 9 is a flowchart showing the control of gripping in the normal opening and closing of the chuck 15. This is shown in FIG.
9 shows processing in the case of the control of (a) and (b).
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 process 601,
High speed V1, torque limit value T1 from evacuation point to shift position
Starts the movement of the gripping claws 30.

In the next judgment 602, 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 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 gripping claw 30 is started at the low speed V2 and the torque limit value T2 to the calculated gripping position. The value of the speed V2 is automatically set to the speed V2a or V2b according to the magnitude relationship between the set value of the gripping force and the switching gripping force as described above. If the set value of the gripping force is smaller than the switching gripping force, the speed V2 is changed to the speed V2a.
Is performed, the driving torque and the gripping force are converted based on the low gripping force calibration data Da, and the torque limit value T2 is obtained. If the set value of the gripping force is equal to or greater than the switching gripping force, the gripping operation is performed with the speed V2 set to the speed V2b, and the torque limit value T2 is obtained from the high gripping force calibration data Db.

In the next judgment 606, it is judged whether or not the driving 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, and it is determined 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 claw 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 rotation of the spindle is controlled 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 moves at a high speed at a position away from the gripping position, and the gripping claw 30 reliably 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.

Further, when the set value of the gripping force is in the low gripping force region and in the high gripping force region, the gripping speed V2
Is automatically switched, and the gripping force calibration data for converting the driving torque and the gripping force is also automatically switched, so that the gripping force can be accurately controlled in the low gripping force region, In the high gripping force region, it is possible to reduce the time required for gripping by setting the gripping speed to the high speed V2b.

Also, in many cases, the set value of the gripping force is set to the low gripping force region in the case of secondary processing (back processing) such as finishing.
In this case, since the gripped portion of the workpiece is processed to a size within a predetermined tolerance by the primary processing (front processing), the shift point can be set near the gripping diameter, and the gripping speed V2 is reduced to the low speed V2a.
Even so, the influence on the holding time is small. In addition, when the gripping speed is high, the variation in the gripping force of the workpiece due to the drive torque control is slightly large, but in the high gripping force region, the workpiece can be gripped firmly, so a slightly larger gripping force is set. If you do, there is no effect.

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. 10 is a flowchart showing control of release of the chuck 15 during normal opening and closing. This shows the processing in the case of the control of 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. 11 is a flow chart 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. 8A and 8C. 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 value of the speed V2 is automatically set to the speed V2a or V2b according to the magnitude relationship between the set value of the gripping force and the switching gripping force as described above. The gripping force calibration data for converting the driving torque and the gripping force is also automatically switched. 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. 12 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 value of the speed V2 in this case is set to the speed V2b. 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 driving 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.

A set value selection change program 544 as a set value selection change means is configured to execute processing for selecting or changing chucking data when a predetermined command is programmed in the NC machining program and the command is executed. 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. 13 and 14, selection of a set of chucking data (parameter group No.) from the NC machining program and change of data such as gripping force will be described.
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. 13C 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. 13 (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 according to 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. 14C 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.

As described above, since the chuck capable of moving the gripping claws in a wide range can be controlled while selecting and changing 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.

As described above, in the electric chuck having a large gripping claw movement stroke and applicable to a wide range of workpieces, the gripping claw speed is controlled to be switched between high speed and low speed in accordance with the position of the gripping claw. In addition, the gripping time can be reduced despite the large stroke. In the case of opening and closing drive by the spindle motor, high-speed and low-speed gripping claws can be performed by rapid feed of C-axis feed and machining feed, thereby simplifying 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-described 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.

Although the description has been made with reference to the two types of calibration data of the low gripping force calibration data Da and the high gripping force calibration data Db, three or more types of calibration data may be provided. For example, the gripping force may be controlled in accordance with three types of calibration data including medium gripping force calibration data at a medium gripping speed.

Further, the moving speed is kept constant, and the interval for obtaining the relation data between the gripping force and the driving torque of the drive motor (the interval of the driving torque for actually measuring the gripping force) is changed according to the magnitude of the gripping force. The relationship data between the gripping force and the driving torque of the drive motor may be obtained to control the gripping force. That is, in the low grip force calibration data area, the interval is reduced to obtain the relation data, and in the high grip force calibration data area, the interval is increased to obtain the relation data and stored.

[0116]

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

Relational data for automatically switching the value of the gripping speed when the set value of the gripping force is in the low gripping force area and in the case of being in the high gripping force area, and for converting the driving torque and the gripping force. Is also automatically switched, so that the gripping force can be accurately controlled in the low gripping force area, and the gripping speed can be increased in the high gripping force area to reduce the time required for gripping. Become. In addition, since the gripping force of the workpiece can be input and the opening and closing of the gripping claws are controlled by the drive motor according to the set value of the gripping force, the workpiece can be gripped with an appropriate gripping force according to the type of the workpiece. In addition, the workpiece is not deformed by an excessive gripping force, and the workpiece does not drop from the chuck due to an insufficient gripping force.
That is, it is possible to grip the workpiece with a wide range of gripping force.

Since a plurality of relational data indicating the relation between the gripping force and the driving torque are narrower at intervals for obtaining the relation in one relational data than in the other relational data, high-precision gripping force control is required. The accuracy and reliability of the relational data in the low gripping force region can be improved, and the accuracy and reliability of the gripping force in the low gripping force region can be improved.

Since the switching gripping force for switching the control of the gripping claws can be set, the boundary value between the low gripping force region and the high gripping force region can be set to an arbitrary value according to the characteristics of the chuck. .

Since the movement of the gripper is stopped when the drive torque of the drive motor reaches the set value, it is possible to prevent the chuck and the workpiece from being damaged by an excessive gripping force.

Since the opening and closing drive of the gripping claws is performed by the spindle motor, the driving mechanism of the gripping claws can be simplified, and the number of drive motors does not need to be increased, and the cost of the machine tool can be reduced. it can. Furthermore, the high-speed movement and the low-speed movement of the gripping claws can be performed by the C-axis feed rapid feed and the machining feed, thereby simplifying the control.

[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 showing a gripping force calibration screen displayed on a display unit.

FIG. 6 is a diagram showing a chuck setting screen displayed on a display unit.

FIG. 7 is a diagram illustrating control of the position and speed of a gripping claw when the chuck is normally opened and closed;

FIG. 8 is a diagram illustrating the control of the position and speed of the gripping claws during setup opening and closing of the chuck.

FIG. 9 is a flowchart showing control of normal gripping of the chuck.

FIG. 10 is a flowchart illustrating control of normal release of the chuck.

FIG. 11 is a flowchart showing control of setup chucking of a chuck.

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

FIG. 13 is a diagram illustrating an example of an NC machining program for selecting a set of chucking data.

FIG. 14 is a schematic 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 (15)

[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 a plurality of moving speeds of the gripping claw (30). Storing a plurality of relationship data (Da, Db) indicating a relationship between the gripping force and the drive torque of the drive motor (4); and storing the plurality of relationship data corresponding to the set value of the gripping force. (Da, Db) to make one of the relational data valid, and controlling the gripping force. 2. 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 torque controllable. A method of controlling a chuck, comprising: inputting a set value of a gripping force, which is a force of the gripping claw (30) gripping a workpiece; A plurality of relationship data (Da, Db) indicating a relationship, wherein an interval for obtaining a relationship between the gripping force and the drive torque of the drive motor (4) in one relationship data (Da) is other relationship data ( Db) a procedure for storing a plurality of relational data (Da, Db) smaller than the interval in Db), and one of the plurality of relational data (Da, Db) corresponds to the set value of the gripping force. Valid And so, the control method of an electric chuck having a procedure for controlling the gripping force using the narrow relationship data spaced at the required gripping force control detail area (Da). 3. The electric chuck control method according to claim 1, wherein the plurality of related data (Da, Db) are used when the moving speed of the gripping claw (30) is a first speed. The low gripping force calibration data (Da) indicating the relationship between the gripping force and the driving torque, and the moving speed of the gripping claw (30) are the first speed.
High gripping force calibration data (D) indicating the relationship between the gripping force and the drive torque when the second speed is higher than the second speed.
b) at least two data, wherein the control procedure sets the moving speed of the gripping claw (30) to the first speed and the low gripping force calibration data in accordance with the set value of the gripping force. Whether to control the gripping force according to (Da) or to control the gripping force according to the high gripping force calibration data (Db) while setting the moving speed of the gripping claw (30) to the second speed. A control method for an electric chuck that performs control by switching. 4. A method for controlling an electric chuck according to claim 3, further comprising a step of storing a switching gripping force that is a value of the gripping force for switching control of the gripping claw (30). In the control procedure, when the set value of the gripping force is smaller than the switching gripping force, the moving speed of the gripping claw (30) is set to the first speed and the low gripping force calibration data (D
a) controlling the gripping force according to a), and when the set value of the gripping force is equal to or greater than the switching gripping force, the gripping claw (30);
And controlling the gripping force according to the high gripping force calibration data (Db). 5. The control method for an electric chuck according to claim 1, wherein the drive torque of the drive motor reaches a value corresponding to the set value of the gripping force. A method for controlling an electric chuck, comprising the step of stopping the movement of the gripping claws (30). 6. The control method for an electric chuck according to claim 1, wherein the chuck is rotatably supported on a headstock of a machine tool. A method for controlling an electric chuck provided in a vehicle. 7. The control method for an electric chuck according to claim 6, wherein the drive motor (4) rotates and positions the spindle (2) around a spindle axis. 15) a procedure of setting the main body (20) to a fixed state in which the main body (20) cannot rotate with respect to the machine body of the machine tool; and controlling the drive motor (4) while the main body (20) is in the fixed state. Performing the opening and closing operation of the gripping claw (30). 8. A control device for an electric chuck 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. (15) a drive motor (4) that can open and close the gripping claws (30) to control a gripping force that is a force with which the gripping claws (30) grip the workpiece; A plurality of relationship data (Da, Da,) indicating a relationship between the gripping force and the driving torque of the drive motor (4) in accordance with the input means (59) for inputting and the plurality of moving speeds of the gripping claws (30) Db) storing means (552, 553), and the gripping claw such that one of the plurality of pieces of relational data (Da, Db) becomes valid corresponding to the set value of the gripping force. (30) gripping claw system for controlling gripping force A control device for an electric chuck having control means (50). 9. A control device for an electric chuck, 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. (15) a drive motor (4) that can open and close the gripping claws (30) to control a gripping force that is a force with which the gripping claws (30) grip the workpiece; Input means (59) for inputting, a plurality of relation data (Da, Db) indicating a relation between the gripping force and the drive torque of the drive motor (4), wherein Means for storing a plurality of relational data (Da, Db) in which an interval for obtaining a relationship between a gripping force and the drive torque of the drive motor (4) is smaller than an interval in other relational data (Db); Corresponding to the set value of One of the plurality of relational data (Da, Db) is made valid, and the gripping claw is used by using the relational data (Da) having a narrow interval in an area where high-precision gripping force control is required. A control device for an electric chuck, comprising: gripping claw control means (50) for controlling gripping force of (30). 10. The control device for an electric chuck according to claim 8, wherein said means for storing said plurality of related data is provided when said moving speed of said gripping claw is a first speed. Means (552) for storing low gripping force calibration data (Da) indicating the relationship between the gripping force and the driving torque;
Means (553) for storing high gripping force calibration data (Db) indicating a relationship between the gripping force and the driving torque when the moving speed of 0) is a second speed higher than the first speed.
The gripping claw control means (50) sets the moving speed of the gripping claw (30) to the first speed and adjusts the gripping force according to the low gripping force calibration data (Da). The gripping claw (3) is switched by performing control or controlling the gripping force according to the high gripping force calibration data (Db) while setting the moving speed of the gripping claw (30) to the second speed.
0) A control device for an electric chuck for controlling the gripping force. 11. The control device for an electric chuck according to claim 10, further comprising: means for storing a switching gripping force which is a value of the gripping force for switching control of the gripping claw (30). When the set value of the gripping force is smaller than the switching gripping force, the gripping claw control means (50) sets the moving speed of the gripping claw (30) to the first speed and sets the low gripping force calibration data ( The driving torque is controlled according to Da), and when the set value of the gripping force is equal to or greater than the switching gripping force, the moving speed of the gripping claw (30) is set to the second speed and the high gripping force calibration data is set. A control device for an electric chuck for controlling the driving torque according to (Db). 12. The control device for an electric chuck according to claim 8, wherein said gripping claw control means (50) includes said drive motor (4).
The electric chuck control device stops the movement of the gripping claw (30) when the driving torque reaches a value corresponding to the gripping force set value. 13. The control device for an electric chuck according to claim 8, wherein the chuck (15) is rotatably supported on a headstock of a machine tool. The control device for the electric chuck, which is provided in the device. 14. The control device for an electric chuck according to claim 13, wherein the main body (20) of the chuck (15) is in a fixed state in which the main body (20) cannot rotate with respect to the machine body of the machine tool; A chuck rotation fixed switching means for switching a part (20) to a released state in which the part (20) is rotatable with respect to the machine tool body; and the drive motor (4) moves the spindle (2) around a spindle axis. The gripping claw control means (50) controls the chuck rotation fixing switching means to bring the main body (20) into the fixed state, and controls the drive motor (4). The gripping claws (3
A control device for an electric chuck which performs the opening and closing operation of 0). 15. The control device for an electric chuck according to claim 14, wherein said chuck rotation fixing switching means is capable of relative rotation between said main body (20) and said main shaft (2) in said fixing state. A control device for the electric chuck, wherein relative rotation between the main body (20) and the main shaft (2) is disabled in the released state.