JP2001096409A - Method and apparatus for controlling electric chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for controlling electric chucks that can automatically and correctly set the position of speed-change points for electric chucks with gripping jaws with moving speed changed to a low one at a speed-change point in the middle of gripping operations. SOLUTION: The control method for electric chucks with gripping jaws opened and closed by a drive motor to grip work comprises a procedure of inputting a gripping point whereat the work is gripped and the drive motor is stopped, a procedure of computing a speed-change point whereat the moving speed of the gripping jaws is changed, at least depending on the gripping point and the radial dimensional dispersion of the gripped portion of the work, and a procedure of controlling the rotation of the drive motor so that the gripping jaws are moved in the gripping direction or from a retracted point whereat gripping operations start to the speed-change point at a first speed and then moved from the speed-change point to the gripping point at a second speed lower than the first speed, at which gripping point they are driven to grip the work.

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 drive motor, and more particularly, to switching a moving speed of a gripping claw to a low speed at a shift point during a gripping operation. The present invention relates to a method and an apparatus for controlling an 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. In addition, fine control using a combination of the position on the closed side of the gripping claw (grip position) and the driving torque of the servomotor, and control for switching the moving speed of the gripping claw depending on the position of the gripping claw could not be performed. .

Accordingly, the present applicant has filed Japanese Patent Application No. 10-301.
No. 901 proposed a control method and a device for an electric chuck, and disclosed a technique of inputting information of a gripping point, a shift point, and a retreat point, and switching a moving speed of a gripping claw from a high speed to a low speed at a shift point. However, when inputting the shift point in this way, if the position of the shift point is incorrectly input, the gripping claws collide with the workpiece at a high speed, and the electric chuck, the workpiece and the machine tool are damaged. There was also a risk of doing it.

Accordingly, the present invention provides a method of controlling an electric chuck in which the position of a shift point can be automatically set without error in an electric chuck that switches the moving speed of a gripping claw to a low speed at a shift point during a gripping operation. And an apparatus.

[0007]

In order to achieve the above object, a method for controlling an electric chuck according to the present invention comprises opening and closing a gripper of a chuck supported by a frame provided on a body of a machine tool by a drive motor. A control method of an electric chuck for gripping an object to be gripped, wherein a position at which the gripping claw stops moving when the object to be gripped is gripped by the gripping claw is set as a gripping point, and at least the gripping point A step of calculating a shift point that is a change position of the moving speed of the gripping claw from the variation amount of the radial dimension of the gripped portion of the gripped object and the gripping claw at a start position of the gripping operation. To move in a gripping direction at a first speed from a certain evacuation point to the shift point, and to move at a second speed lower than the first speed until gripping the object to be gripped from the shift point, The drive motor Rotation control to the by the gripping claws are those having a step of gripping the object to be grasped.

In the above-described electric chuck control method, a step of inputting a set value of a gripping force, which is a force of the gripping claw gripping the gripped object, when setting the gripping point, When the gripping force is gripped by the gripping force, the amount by which the driving motor is further driven in the gripping direction from when the gripping claw contacts the gripped object to when the gripped object is gripped by the gripping force. Calculating the shift amount from a set value of the gripping force, and calculating the shift point.
It is preferable that the shift point is calculated from at least the grip point, the variation amount, and the tightening amount.

In the above-described electric chuck control method, a step of inputting a set value of a gripping diameter of the object to be gripped is provided, and the step of setting the gripping point is performed by the step of setting the gripping diameter of the object to be gripped. Is preferably held by the gripping claw, and the stop position of the gripping claw at that time is set as the gripping point.

In the above-mentioned electric chuck control method, a step of inputting a set value of a gripping diameter of the object to be gripped is provided, and the step of setting the gripping point is performed by using a reference object having a known gripping portion dimension. A procedure of causing the gripper of the gripper to grip the gripper, a procedure of inputting the gripper size of the reference gripper, a current radial position data of the gripper, and the gripper diameter It is preferable to include a procedure of setting the gripping point from the set value of the above and the size of the gripped portion.

In the above-described method for controlling an electric chuck, a step of inputting a retreat amount, which is an amount of movement of the grasping claw from the grasp point to the retreat point, includes retreating from the grasp point and the retreat amount. And a procedure for calculating points.

In the above-described electric chuck control method, the step of calculating the shift point may be such that the shift point is the same as the retract point when the calculated shift point exceeds the retreat point to the release side. It is preferable to set the position.

[0013] Further, the electric chuck control device of the present invention is supported by a frame provided on the body of a machine tool,
An electric chuck control device that controls a chuck that opens and closes gripping claws and grips an object to be gripped, comprising: a drive motor that drives the gripping claws of the chuck to open and close; and the gripping claws grip an object to be gripped. Changing the moving speed of the gripping claw based on at least input means capable of setting and inputting a gripping point which is a position where the movement is stopped, and at least a variation in a radial dimension of the gripping point and a gripped portion of the gripped object. Means for calculating a shift point that is a position, and moving the gripping claw in a gripping direction at a first speed from a retreat point that is a gripping start position to the shift point, and moving the gripped object from the shift point. Gripping claw control means for controlling the rotation of the drive motor so as to move at a second speed lower than the first speed until gripping, and gripping the object to be gripped by the gripping claws. is there.

In the control device for an electric chuck, the input means can input a set value of a gripping force which is a force of the gripping claw gripping an object to be gripped when setting the gripping point. When gripping the object to be gripped with the gripping force, the drive motor is further driven in the gripping direction until the gripping claw contacts the object to be gripped and then grips the object to be gripped with the gripping force. Means for calculating a tightening amount that is an amount to be performed from the set value of the gripping force, wherein the means for calculating the shift point includes at least the shift point based on the grip point, the variation amount, and the tightening amount. Is preferably calculated.

In the above-described electric chuck control device, the input means can input a set value of a gripping diameter of the object to be gripped, and the gripper can set the gripping diameter by the gripping claw. It is preferable that the user can be gripped and set and input the stop position of the gripping claw at that time as the gripping point.

In the above-described electric chuck control device, the input means inputs a set value of a gripping diameter of the object to be gripped and the size of the gripped portion of a reference object to be gripped having a known size of the gripped portion. The gripping claw control means allows the gripping portion of the gripping claw of the chuck to grip the reference gripped object having the gripped portion size input,
It is preferable that the grip point can be set based on the current radial position data of the grip portion, the size of the grip portion, and the set value of the grip diameter.

In the above-described electric chuck control device, the input means can input a retreat amount, which is a movement amount of the grip claw from the grip point to the retreat point. It is preferable to have means for calculating the retreat point from the grip point and the retreat amount.

In the above-described control device for an electric chuck, the means for calculating the shift point may be such that when the calculated shift point exceeds the retreat point to the release side, the shift point is set to the same as the retreat point. It is preferable to set the position.

[0019]

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 equal angle 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.

While the main body 20 of the chuck 15 is 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 main spindle 2, and calculates 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. Further, the gripping claw position calculation program 542 also has a function of calculating the positions of a shift point and a retreat point of the gripping claw 30 described later.

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 in the relationship between the driving torque and the gripping force for each chuck 15, the correspondence between the torque and the gripping force is stored as a table in a torque calibration parameter 552 described later. 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. In the parameter memory 55, a region for the chuck basic parameter 551 and a region for the torque calibration parameter 552 are set.

The chuck basic parameters 551 are various parameters specific to the chuck displayed on the chuck maintenance screen (see FIG. 4) of the display means 58, and are set by the machine tool maker. Normally, the user does not change the chuck basic parameters 551. The torque calibration parameter 552 is a parameter for calculating the relationship between the torque limit value of the spindle motor 4 and the gripping force of the chuck 15 by the gripper 30. For example, the distance between the maximum torque and the minimum torque of the spindle motor 4 is divided into ten equal parts to make 10, 20, 3
The gripping force for a torque of 0,..., 100% is actually measured and stored. Interpolation calculation is performed assuming that the gripping force for the intermediate torque is on a straight line.

The interval between torques to be measured and stored is 10%
The interval is not limited to this, and may be an arbitrary interval, and may not be an equal interval.
Further, a relational expression between the torque and the gripping force may be stored as a mathematical expression. The torque calibration parameter 552 is also a chuck-specific parameter set by the machine tool maker.
Normally, the user does not change this, but it can.

Furthermore, 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. 5) 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 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 a screen for the machine tool maker to set the chuck basic parameters 551 or for performing maintenance of the machine tool. The screen is designed so that the user cannot change the chuck basic parameters 551 from this screen. I have. The chuck basic parameters 551 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. When the "setting" key of the function key is pressed from this screen, a chuck setting screen of FIG. 5 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 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). V1, V2, V
The unit of 3 is rotation / minute.

FIG. 5 is a view 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 data file 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 retreat amount is a numerical value for setting the retreat point of the grasping claw 30, that is, the starting position of the grasping operation. The retreat amount is the amount of movement from the grip point, which is the position where the grip claw 30 grips the workpiece, to the retreat point. The grip diameter is the same as the grip point, and is a set value of the grip position of the workpiece. The variation in the gripping diameter indicates a variation in the gripping diameter, that is, the dimension of the gripped portion of the workpiece (material), and sets a deviation from the median of the upper limit value and the lower limit value of the dimension. The core diameter is
This is the diameter value of the core metal used when processing the gripping nail as a raw nail. Numerical values relating to the position of the gripping claw 30 such as the retracted amount and the gripping diameter (grip point) are numerical values displayed in diameter.

The operator can set these chucking data, assign a desired data file 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. The line at the cursor position is additionally displayed with a dotted underline. In FIG. 5, the cursor is on the line of the variation in the grip diameter,
This value can be entered.

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.

Below the chucking data, the data of the current position of the gripping claw 30 and the gripping point are displayed. However, the values of these data are internal data of the NC device 50, and the current nail position 35.0 mm corresponds to the diameter coordinate value of the chucking data of 150.0 mm, and the grip point 15.
0mm is the diameter coordinate value of chucking data 130.0mm
Corresponding to The teaching conditions are displayed below these data. The teaching condition is a gripping condition when a teaching operation described later is performed.

On the right side of the screen, an image indicating the positional relationship between the retreat point, the shift point, and the grip point is displayed. The retreat point is a point where the gripping claw 30 is located at the start of the gripping operation, and is also a position where the gripping claw 30 is retracted when the workpiece is released. The retreat point is set at a position moved from the grip point to the release side by the retreat amount. The retracted amount b is set to a positive value for external tightening and a negative value for internal tightening.
Assuming that the grip point is the position R, the retreat point is calculated by the equation P = R + b.

This calculation is performed by the gripping claw position calculation program 5
42, and the calculated evacuation point is stored in a predetermined storage area. In the case of the numerical values shown in FIG.
The position is 5.0 mm (diameter coordinate value: 150.0 mm).
Since the retreat amount is substantially constant irrespective of the size of the workpiece, the retreat amount is input and the retreat point is calculated from the gripping point and the retreat amount, thereby reducing mistakes in setting the retreat point.

The shift point is a position where the gripping claw 30 is shifted from a high-speed movement to a low-speed movement. As described later, the gripping claw 30
Moves at a high speed V1 (approach speed) from the retreat point to the shift point, and moves at a low speed V2 (gripping speed) from the shift point to the stop point. The position Q of the shift point is calculated from the position R of the grip point, the variation amount e, and the tightening amount a by the grip claw position calculation program 542 according to the following Expressions 1 and 2. For external tightening: Q = R + e + a (Equation 1) For internal tightening: Q = R-ea (Equation 2)

Equations (1) and (2) show that the shift point is located on the release side from the grip point by the amount of variation + the amount of tightening. However, the variation amount is the width of the variation in the dimensions of the gripped portion of the workpiece. For example, when the variation in the grip diameter is ± 1 mm as shown in FIG. 5, the variation is calculated as 1 mm. The tightening amount is an amount further tightened by the spindle motor 4 until a predetermined gripping force is generated after the gripping claw 30 comes into contact with the workpiece when gripping the workpiece. This is the amount tightened by the spindle motor 4 when the object to be gripped (workpiece) is gripped with the teaching gripping force for setting. The tightening amount is measured by the rotation angle of the spindle motor 4, and the rotation angle is converted into the movement amount of the gripping claw 30 and used in the above-described Expressions 1 and 2. The tightening amount is
The value differs depending on the gripping force.

FIG. 6 is a diagram showing an example of the relationship between the gripping force and the tightening rotation angle. This relationship is peculiar to the chuck, and differs for each chuck. Various methods can be considered for determining the tightening amount. The first method is to divide the gripping force into regions of low gripping force and high gripping force according to a certain boundary value, and set the tightening amount to a constant value (maximum value) in each region. The tightening amount in each area is stored in the parameter memory 55.
Remember. For example, when the gripping force is 2000 kgf or less, the tightening amount (tightening rotation angle) is set to 10 deg, and when the gripping force exceeds 2000 kgf, the tightening amount (tightening rotation angle) is set to 60 deg. However, the conversion between the tightening amount a [mm] corresponding to the gripping claw movement amount (diameter display) and the tightening rotation angle θ [deg] of the spindle motor is performed by a conversion formula a = k · θ. In the chuck of this example, the conversion constant k is 0.017.

The second method is a method in which the relationship as shown in FIG. 6 is stored as a table in the parameter memory 55, and the tightening amount is determined according to the gripping force. Regarding the tightening amount corresponding to the grip force of the numerical value not stored in the table,
What is necessary is just to calculate by linear interpolation etc. The third method is to divide the area of the gripping force into three or more areas and set the tightening amount in each area to a constant value (maximum value). Taking FIG. 6 as an example, the gripping force is 500 kgf or less, more than 500 kgf and 1000 kgf or less, more than 1000 kgf and 2000 kf.
gf or less, and the tightening rotation angle in each area is set to the maximum value in that area. That is, the tightening rotation angle in each area is 3.0 deg in order,
5.0 deg, 10.0 deg...

The tightening rotation angle θ is determined by the first to third methods and the like, and the converted rotation angle is calculated as a tightening amount (gripping claw moving amount) to calculate a shift point by the following equations (1) and (2). The calculation of the tightening amount and the shift point is performed by the gripping claw position calculation program 542.
And the calculated shift point is stored in a predetermined storage area. In the case of the numerical values shown in FIG. 5, when the tightening amount is obtained by the third method, it becomes 25 deg.
The position is 6.425 mm (radial coordinate value 131.425 mm).

Since the shift point is automatically calculated by the equations (1) and (2), an accident occurs in which the operator erroneously sets the shift point and the gripper 30 collides with the workpiece at a high speed. The possibilities are greatly reduced and the safety of the machine tool is improved.
Further, since the position of the shift point that is safe and is closest to the grip point can be calculated by Expressions 1 and 2, the gripping time can be reduced and the work efficiency can be improved.

The calculation of the shift point in the above description is based on the following equation (1)
Equation 2 has been used. By setting the variation amount e to be larger than the actual variation amount by a predetermined amount, for example, omitting the tightening amount in Expressions 1 and 2 and calculating the shift point by the following Expressions 3 and 4 Can also. In the case of outer tightening: Q = R + e Equation 3 In the case of inner tightening: Q = R-e Equation 4 In this case, the shift point calculation method is simplified, and the gripping claw position calculation program 542 is simplified. Thus, the cost of the control device can be reduced.

In Formulas 1 and 2, a shift point can be calculated as Formulas 5 and 6 by looking at a margin by a predetermined margin s for safety. In the case of external tightening: Q = R + e + a + s (Equation 5) In the case of internal tightening: Q = R-e-as (Equation 6) In this case, there is a possibility that the gripping claws 30 collide with the workpiece at high speed. This further reduces the safety of the machine tool.

In the screen of FIG. 5, when the operator inputs a variation in the gripping diameter, if the numerical value is set to a value larger than the actual value by misunderstanding the unit, the calculated shift point is closer to the release point than the retreat point. May be located at In this case, if the gripping claw 30 is left as it is, the gripping claw 30 moves in the direction opposite to the original gripping direction by the start of the gripping operation, so that unnecessary movement not only increases the gripping operation time but also involves danger. Therefore, when the shift point is calculated from Equations 1 to 6 and the shift point is located on the release side of the retreat point, it is preferable to store the shift point as the same position as the retreat point.

That is, the retreat point is located at the position P,
Assuming that the shift point calculated by the above is the position Q, in the case of outer tightening: Q = P if Q> P In the case of inner tightening: Q = P if Q <P When the point is located on the release side of the evacuation point, by setting the shift point to the same position as the evacuation point, useless movement of the gripping claw 30 does not occur, and an unexpected danger may be imposed on an operator or the like. Absent. Such calculation of the shift point and the evacuation point is performed when the set of chucking data is changed.
This may be performed when the retracted amount of the chucking data, the gripping diameter, the variation in the gripping diameter, or the like is changed, or when the gripping claw 30 is gripped in the normal open / close mode.

When the "maintenance" key of the function key is pressed from the screen of FIG. 5, 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 deviate, an object to be gripped having a known diameter is formed at the formed gripping portion of the gripping claw 30 of the chuck 15 as will be described later with reference to FIGS. Hold in the setup open / close mode, and press the “Teach” key on this chuck setting screen. Then, "Do you want to teach? Y / N" is displayed. When the gripping diameter data (130.0 mm in the example of FIG. 5) and the diameter of the gripped object on the chuck setting screen are the same, , When “Y” is input, the gripping claw current position matches the gripping point (1 in the example of FIG. 5).
5.0 mm). If they are not the same, "N" is input, and a known diameter value is input as the teaching grip diameter. The known object to be grasped may be a workpiece in which the dimensions of the grasped portion are measured.

In the example of FIG. 5, the data of the grip diameter is 130.0.
When the object to be gripped having a diameter of 129.5 mm is gripped, the data of the gripping claw current position becomes 14.5 mm. By inputting the diameter value of 129.5 mm, the diameter value of the diameter coordinate system of 129.5 mm is obtained. 5mm and gripping claw current position 14.5
mm. That is, the gripping diameter 130.0 mm in the radial coordinate system corresponds to the gripping claw current position 15.0 mm. Then, a gripping claw current position (internal data of the NC device 50) of 15.0 mm is set as a gripping point corresponding to a gripping diameter of 130.0 mm.

In this manner, the position of the gripping claw in the NC device 50 and the actual gripping position of the gripping claw 30 are matched, and the current gripping claw position is associated with the gripping diameter in the radial coordinate system. . In the example of FIG. 5, when the object to be gripped (workpiece) having a gripping diameter of 130.0 mm is gripped, the gripping claw current position is 1
5.0 mm. The gripping diameter and gripping force at the time of teaching are stored in the chucking data memory 57 as the teaching gripping diameter,
It is stored as the teaching gripping force. The processing of this teaching is performed by the chuck control program 541.

When the "teach" key is pressed in this way, the current position of the gripping claw 30 is associated with the "grip diameter" data, and the gripping point is automatically set. This processing is performed by the grip claw position calculation program 542. The gripping point can be automatically set only by gripping the workpiece and pressing the "teach" key, thereby reducing input errors.

It is to be noted that the setting of the grip point is not performed by the "teach" key, but the "grip point" key is provided, and the object to be gripped having a gripped portion having the same diameter as the grip diameter set value of the chucking data (working tool) is provided. The object can be set by pressing the “grip point” key with the gripper 30 gripping the object. In this case, grip force and grip diameter data when the “grip point” key is pressed are stored as grip point conditions. Then, immediately before the gripping claw 30 is gripped in the normal open / close mode or the like,
The shift point is calculated based on the tightening amount obtained from the grip force when the "grip point" key is pressed.

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.

When the gripper 30 grips the workpiece and the driving torque of the spindle motor 4 reaches the 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 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. 7 (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. 8 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. 8 (a) shows the case of the outside clamping in the 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 an extremely low speed V3 from the stop point based on the torque limit value T2 to the gripping point at each predetermined angle and stops at the nearest gripping point is shown in FIG.
Same as (a).

FIG. 8B shows a state in which the gripping claws 3 are opened and closed.
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. FIG. 8 (c) shows a case of inner tightening grip in setup opening and closing. Fig. 8
This is the same as the speed control in (a). 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 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 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, it waits until the movement is completed in the judgment 611, and when the movement is completed, the process proceeds to the judgment 612, and it is judged whether or not the stop position is within an allowable error. 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 gripping 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.

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 in 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 flowchart showing the control of 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 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, this 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 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 it is determined in the determination 652 that the torque limit value T1 has not been reached, it is determined in a determination 653 whether 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 a process for selecting and 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.

Referring to FIG. 13 and FIG. 14, a set of chucking data (data file N
o. The selection of (1) and the change of data such as gripping force 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 data file N
o. The content of each data of the set of ten chucking data is shown.

The program for 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)
In the data file No. 12 shows the contents of each data of a set of twelve chucking data.

Further, 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 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 gripping force, “2” indicates gripping diameter, “3” indicates gripping diameter variation, and “4” indicates retreat amount. Can change data. 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 amount of the same set number 10 is changed to 8 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 moving stroke of the gripping claws and applicable to a wide range of workpieces, the speed of the gripping claws is controlled to be switched between high speed and low speed in accordance with the position of the gripping claws. 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.

Further, 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.

[0116]

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

Since the speed of the gripping claw is switched between high speed and low speed in accordance with the position of the gripping claw, gripping time can be reduced and secure gripping can be performed. Further, since the shift point is automatically calculated at least from the grip point and the variation amount of the workpiece size, the position of the shift point can be automatically set without error, and the gripping claw can be machined at a high speed. The possibility of occurrence of an accident such as collision with an object is greatly reduced, and the safety of the machine tool is improved.

Since the tightening amount is calculated from the set value of the gripping force, and the shift point is automatically calculated from at least the gripping point, the variation in the size of the workpiece, and the tightening amount, a safe and gripping point is obtained. Since the position of the shift point closest to the above can be calculated, the gripping time can be shortened and the working efficiency can be improved.

Since the grip point can be automatically set by gripping the workpiece, input errors of the grip point are reduced.

Since a workpiece having a known gripping portion size is gripped and the gripping nail position managed by the control device is made to coincide with the actual gripping nail position, the gripping point can be set. Operation became easy.

Since the evacuation amount is input and the evacuation point is calculated from the grip point and the evacuation amount, mistakes in setting the evacuation point are reduced.

When the calculated shift point is located on the release side of the retreat point, the shift point is set to the same position as the retreat point, so that no unnecessary movement of the gripping claws occurs and the work efficiency is improved. Also, the safety of the machine tool 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 showing a chuck setting screen displayed on a display unit.

FIG. 6 is a diagram illustrating an example of a relationship between a gripping force and a tightening amount;

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 (12)

[Claims] 1. A control method of an electric chuck for gripping an object to be gripped by opening and closing a gripping claw (30) of a chuck (15) supported by a frame provided on a body of a machine tool by a drive motor (4). A procedure for setting a position where the gripping claw (30) stops moving when the gripping object is gripped by the gripping claw (30) as a gripping point; A procedure for calculating a shift point, which is a change position of the moving speed of the gripping claw (30), from a variation amount of a radial dimension of the gripping part; To move in a gripping direction at a first speed from the retreat point to the shift point, and to move at a second speed lower than the first speed until gripping the object to be gripped from the shift point,
By controlling the rotation of the drive motor (4), the gripping claws (3
0) a step of gripping the object to be gripped. 2. The control method for an electric chuck according to claim 1, wherein a set value of a gripping force, which is a force of the gripping claw (30) gripping an object to be gripped when the gripping point is set, is set. Inputting, and when the object to be gripped is gripped with the gripping force, the driving is performed until the gripping claw (30) contacts the object to be gripped and then grips the object to be gripped with the gripping force. Calculating a tightening amount, which is an amount for further driving the motor (4) in the gripping direction, from the set value of the gripping force. The step of calculating the shift point includes at least the gripping point and the variation amount. A control method for an electric chuck, wherein the shift point is calculated from the torque and the tightening amount. 3. The control method for an electric chuck according to claim 1, further comprising a step of inputting a set value of a grip diameter of an object to be gripped, and setting the grip point. The procedure is such that the object to be gripped having the gripping diameter set is gripped by the gripping claw (30), and a stop position of the gripping claw (30) at that time is set as the gripping point. Method. 4. The method for controlling an electric chuck according to claim 1, further comprising a step of inputting a set value of a grip diameter of an object to be gripped, and setting the grip point. The procedure is to input a reference gripping object having a known gripping portion size to the gripping portion of the gripping claw (30) of the chuck (15), and input the gripping portion size of the reference gripping object. And a step of setting the gripping point from the current radial position data of the gripping portion, the set value of the gripping diameter, and the size of the portion to be gripped. 5. The control method for an electric chuck according to claim 1, wherein a retracted amount, which is an amount of movement of the gripping claw from the gripping point to the retreat point, is determined. A control method for an electric chuck, comprising: a step of inputting; and a step of calculating the retreat point from the grip point and the retreat amount. 6. The control method of an electric chuck according to claim 1, wherein the step of calculating the shift point includes the step of calculating the shift point such that the calculated shift point moves the retreat point to a release side. A control method for an electric chuck, wherein the shift point is set to the same position as the retreat point when the shift point is exceeded. 7. 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 an object to be gripped, A drive motor (4) for opening and closing the gripping claws (30) of the chuck (15), and a gripping point at which the gripping claws (30) grip an object to be gripped and stop moving can be set and input. Input means (59)
Means (54) for calculating a shift point, which is a change position of the moving speed of the gripping claw (30), from at least the gripping point and the amount of variation in the radial dimension of the gripped portion of the gripped object.
2) and moving the gripping claw (30) in a gripping direction at a first speed from a retreat point, which is a gripping operation start position, to the shift point, until the gripping object is gripped from the shift point. The drive motor (4) is rotationally controlled to move at a second speed lower than the first speed, and the gripper (3)
0), the gripper control means (5) for gripping the object to be gripped.
0). 8. The control device for an electric chuck according to claim 7, wherein said input means (59) is a force by which said gripping claw (30) grips an object to be gripped when setting said gripping point. When the gripping object is gripped with the gripping force, the gripping claw (30) abuts on the gripped object, and then grips the gripped object. Means (542) for calculating, from the set value of the gripping force, a tightening amount which is an amount for further driving the drive motor (4) in the gripping direction until gripping by force; and means for calculating the shift point. (542) The control device for an electric chuck, wherein the shift point is calculated from at least the grip point, the variation amount, and the tightening amount. 9. The control device for an electric chuck according to claim 7, wherein said input means is capable of inputting a set value of a grip diameter of an object to be gripped. The gripping object is gripped by the gripping claw (30) with the gripping diameter set, and the stop position of the gripping claw (30) at that time can be set and input as the gripping point. Chuck control device. 10. A control device for an electric chuck according to claim 7, wherein said input means (59) comprises: a set value of a grip diameter of a grip target and a known grip portion. The grip claw control means (50) is capable of inputting the gripped portion dimensions of a reference gripped object having dimensions, and The gripping portion of the gripping claw (30) of the chuck (15) is gripped, and the gripping point is set from the current radial position data of the gripping portion, the size of the gripped portion, and the set value of the gripping diameter. A control device for an electric chuck that is capable of doing so. 11. The control device for an electric chuck according to claim 7, wherein said input means (59) is provided with said gripping claw (30) from said gripping point to said retreating point. A control device for an electric chuck having a means (542) for calculating a retreat amount from the gripping point and the retreat amount, which is capable of inputting a retreat amount that is a moving amount of the reciprocating motion. 12. The control device for an electric chuck according to claim 7, wherein the means for calculating the shift point is such that the calculated shift point corresponds to the retreat point. A control device for an electric chuck, wherein the shift point is set to the same position as the retreat point when the shift point is exceeded.