JP2002210635A - Instrumentation method of workpiece dimension by electric chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an instrumentation method of a workpiece dimension that can measure a dimension of a workpiece by detecting the positions of holding jaws when the workpiece is held by an electric chuck of a machine tool. SOLUTION: The instrumentation method of a workpiece dimension by an electric chuck measures a dimension of the workpiece by holding the workpiece with the holding jaws 30 of the chuck 15 supported on a frame arranged on a bed of the machine tool. The chuck holds the workpiece through opening and closing motion of the holding jaws by a positionally controllable drive motor 4, and allows the held workpiece to be machined by a machining tool. A procedure is set to store a relation between positions of the holding jaws and the workpiece dimension, and a procedure is set to hold a given machined region of the workpiece machined by the machine tool with the holding jaws and under a given holding condition and compute an actually measured dimension of the machined region from the positions of the holding jaws in the state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the size of a workpiece by detecting the position of a gripping claw of an electric chuck when gripping the workpiece with an electric chuck of a machine tool. Related to measurement method.

[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. The opening and closing drive of the gripping claws of the chuck is performed by a hydraulic cylinder, a pneumatic cylinder, or the like, or disclosed in WO 98/3.
What is performed by a drive motor as described in No. 6863 is known. After the workpiece is gripped by such a chuck and the workpiece is machined, the dimensions of the machined part of the workpiece are measured by installing a dedicated dimension measuring device or dimension measuring tool. Had to do.

[0003]

SUMMARY OF THE INVENTION Measuring the dimensions of a machined portion of a workpiece immediately after machining the workpiece can be used for confirming the machining dimensions of the workpiece and determining the quality of the machining. This is useful because it can be applied to correcting the tool correction amount in order to correct the position of the processing tool so that the processing dimension of the next workpiece does not fall out of the range of the dimensional tolerance. However, installing a dedicated dimension measuring device or dimension measuring tool on the machine tool for that purpose increases the cost of the machine tool. In addition, in order to measure the dimensions of a workpiece using a dimension measuring device or a dimension measuring tool, it is necessary to operate a dimension measuring machine, and it takes time for the dimension measurement. There was a problem that the efficiency was reduced.

A conventional chuck for gripping a workpiece at the time of machining does not assume that the dimension of the workpiece is measured, but hardware and software for measuring the dimension of the workpiece are prepared. Absent. Therefore, the dimensions of the workpiece cannot be measured by the chuck for processing.

In view of the above, the present invention provides a method for measuring the size of a workpiece, in which when the workpiece is gripped by an electric chuck of a machine tool, the position of a gripping claw of the electric chuck can be detected to measure the dimension of the workpiece. The purpose is to provide.

[0006]

In order to achieve the above-mentioned object, a method for measuring the size of a workpiece using an electric chuck according to the present invention is a method for measuring a workpiece by a gripping claw of a chuck supported on a frame provided on a base of a machine tool. What is claimed is: 1. A method for measuring a workpiece size by an electric chuck which grips an object and measures a dimension of the workpiece, wherein the chuck grips the workpiece by opening and closing the gripping claw by a drive motor capable of position control. And a procedure for storing the relationship between the position of the gripping claws and the size of the workpiece, and a process for storing the relationship between the position of the gripping claw and the dimension of the workpiece. And a step of obtaining the actual measurement size of the processing portion from the position of the gripping claw at that time.

In the method for measuring a workpiece size using the electric chuck, it is preferable that the position of the gripping claw is detected by a rotation angle position of the drive motor.

In the above method of measuring the size of a workpiece using an electric chuck, the step of storing the relationship between the position of the gripping claw and the size of the workpiece includes the step of: It is preferable that the method includes a step of gripping and a step of inputting a known dimension of the reference grasped object while the reference grasped object is grasped.

In the above method of measuring a workpiece size by an electric chuck, a step of inputting a maximum allowable dimension and a minimum allowable dimension of the machining portion, and a step of inputting the actual measured dimension and the maximum allowable dimension and the minimum allowable dimension. It is preferable to have a procedure for performing pass / fail judgment of the workpiece.

In the method for measuring a workpiece size by the electric chuck, a step of inputting a target dimension of the processing part, a step of inputting a tool correction number of a tool for processing the processing part, and a step of inputting the target dimension And a step of obtaining a difference between the tool correction number and the actually measured dimension, and adding the difference to the tool correction amount of the tool correction number.

Further, according to the method for measuring the size of a workpiece by an electric chuck according to the present invention, the workpiece is gripped by one or a plurality of chuck claws supported by a frame provided on a base of the machine tool. A method for measuring the size of a workpiece by an electric chuck that measures the size of the workpiece, wherein the chuck grips the workpiece by opening and closing the gripping claw by a drive motor capable of controlling a position, a moving speed and a gripping force. In addition, the gripped workpiece can be processed by a processing tool, and the workpiece is gripped by the gripping claws at a predetermined processing moving speed and processing gripping force suitable for processing the workpiece. A procedure for performing a predetermined machining on the workpiece, and a predetermined measurement moving speed and a measurement suitable for the measurement of a predetermined machining portion of the workpiece processed by the machine tool. Gripped by the gripping claws of the chuck or another chuck gripping force, and has a procedure for determining the actual dimensions of the machined portion from the position of the gripping claws at the time.

In the method of measuring a workpiece size using the electric chuck, the moving speed for measurement is set smaller than the moving speed for processing, and the gripping force for measurement is set smaller than the gripping force for processing. It is preferred that

In the above method of measuring the size of a workpiece by the electric chuck, after the step of obtaining the actual measured size of the processing portion, the procedure is performed at a predetermined moving speed and a predetermined gripping force suitable for processing the workpiece. It is preferable that the method further includes a procedure of gripping the workpiece with the gripping claws and performing a next process on the workpiece.

In the above method for measuring the size of a workpiece using an electric chuck, a step of gripping a reference object to be gripped having a known size with the gripping claws, and a step of gripping the reference object while holding the reference object to be gripped. And inputting the known dimensions of the object to be gripped.

[0015]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a chuck 15 to which the present invention is applied. The chuck 15 is attached to the tip of the main shaft 2 of the machine tool. Here, as the machine tool, an example of an NC (numerical control) lathe is shown, but other machine tools such as a turning center and a grinding machine may be used.

The spindle 2 is rotatably supported by the headstock 1 and is driven to rotate by a spindle motor 4. A cylindrical bearing retainer 1a is fixed to an inner hole on the front surface of the headstock 1 of the NC lathe. The inner ring of the rolling bearing 3 is fixed to the main shaft 2 by a nut 9. The outer ring of the bearing 3 is inserted and supported in the inner hole of the bearing retainer 1a, and the main shaft 2 is rotatably supported on the headstock 1 by the bearing 3. A front cover 1b is fixed to a front surface of the bearing retainer 1a. A rotor 5 of a built-in motor as a spindle motor 4 is fixed to the outer periphery of the spindle 2. A stator 6 around which a coil is wound is disposed at an outer peripheral position of the rotor 5.
Fixed to.

A cooling passage 8 for passing cooling oil is formed on the outer periphery of the case 7 of the stator 6. By passing the cooling oil through the cooling path 8, the heat generated by the spindle motor 4 is absorbed by the cooling oil and cooled. The structure and function of the built-in motor are known, and a detailed description thereof is omitted here.
At the rear of the spindle 2 and the headstock 1, a detector 412 (FIG. 2) for detecting the rotation speed and rotation angle position of the spindle 2 is provided.
), And a spindle orientation mechanism including a spindle orientation sensor for positioning the spindle 2 at the spindle orientation position.

That is, the spindle motor 4 not only rotates the spindle 2 at a predetermined rotation speed by the speed feedback signal from the detector 412 but also controls the position from the detector 412 by the NC device 50 (see FIG. 2). The control motor is capable of controlling the rotation angle position of the main shaft 2, that is, the movement position of the gripping claw 30 of the chuck 15 by the feedback signal.

A main shaft end 10 having a larger diameter than other portions is integrally formed on the front end surface of the main shaft 2. This spindle end 1
Reference numeral 0 denotes a portion for attaching a face plate, a chuck, a center, and the like. The front end face 11 of the spindle end 10 has a circular face plate 1
2 is fixed by bolts 13. On the face plate 12,
A chuck 15 is attached. A scroll 17, which is a component of the chuck 15, is fixed to a front end face 16 of the face plate 12 with a bolt 18. Scroll 17
Is formed with a spiral scroll groove 19 centered on the center line of the main shaft 2.

A main body 20 is arranged on the outer periphery of the scroll 17. The main body 20 includes a cylindrical first member 21 that is closed so that the front end surface side has a small diameter hole, and an annular second member 22 that engages with the first member 21. An annular second member 22 is fixed to the open rear surface of the first member 21 with a bolt 23. The second member 22 is rotatably supported by the bearing 29 on the outer peripheral side of the scroll 17. As a result, the entire main body 20 is also rotatably supported by the outer peripheral of the scroll 17.

On the front end face of the first member 21, three master jaw guide grooves 25 are formed at equal angles and in the radial direction.
Are slidably inserted. Scroll teeth 28 are formed on the rear surface (the surface on the scroll 17 side) of the master jaw 26. On the front surface of the master jaw 26, a gripping claw 30 for directly gripping a workpiece is fixed with a bolt 31.

The scroll teeth 28 of the master jaw 26 and the scroll grooves 19 on the front surface of the scroll 17 mesh with each other. Therefore, when the rotation of the main body 20 is stopped and the main shaft 2 is driven, the scroll 17 rotates and the master jaw 2 is rotated.
6 is driven in the radial direction and moves together with the gripping claws 30 to grip and release the workpiece. Note that the gripping claw 30 and the master jaw 26 may be integrally configured.
Further, although a case in which three gripping claws 30 are provided is shown, the invention is not limited to this, and an arbitrary plurality of gripping claws may be provided.

The chuck fixing means 40 is a fixing mechanism for fixing the main body 20 to the headstock 1 so as not to rotate. On the outer periphery of the second member 22, a positioning hole 41 is provided.
Are formed in a direction (radial direction) orthogonal to the center axis of the. Further, a positioning member drive mechanism 42 is disposed on the front surface of the headstock 1 and at an outer peripheral position of the chuck 15.
The positioning member drive mechanism 42 has a positioning member 43, which is provided with a piston 44.

The distal end of the positioning member 43 is formed as an insertion portion 45, which is inserted into the positioning hole 41. The piston 44 is slidably inserted into the cylinder 46. Since a pressure fluid such as compressed air or pressure oil is supplied to the cylinder 46 from a pressure fluid passage 47, the piston 44 slides inside the cylinder 46. Whether the insertion portion 45 of the positioning member 43 is at the position inserted into the positioning hole 41 or at the position separated therefrom is detected by a sensor 48 such as a proximity switch or a limit switch.

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 insertion portion 45 is inserted into the positioning hole 41 so that the main body 20 is fixed to a non-rotatable state with respect to a base such as a headstock or a bed of a machine tool. In this fixed state, the spindle 2 is rotationally driven by the spindle motor 4 at a predetermined rotation speed and torque, and the position is controlled so that the gripping claws 30 reach a predetermined gripping diameter position.

By the rotation of the spindle motor 4, the scroll 17 is also rotated together with the spindle 2. Since the scroll teeth 28 of the master jaw 26 and the scroll grooves 19 of the scroll 17 are engaged with each other, when the rotation of the main body 20 is stopped and the main shaft 2 is driven, the master jaw 26 becomes the first jaw.
The member 21 is driven in the master jaw guide groove 25 in the radial gripping direction, and the gripping claw 30 integrated therewith moves to grip the workpiece. To release the gripping of the workpiece, the spindle motor 4 is driven in the reverse direction, and the master jaw 2 is released.
6 is driven in the radial direction of release in the master jaw guide groove 25 of the first member 21, and the gripping claw 30 also moves to release the workpiece.

When the release or gripping operation of the workpiece is completed, the insertion portion 45 is pulled out from the positioning hole 41, and the main body 20 of the chuck 15 can be rotated with respect to the base of the machine tool such as the headstock 1 or the like. And Thus, the main body 20 of the chuck 15 can be driven to rotate together with the main shaft 2, and the workpiece held by the chuck 15 can be machined.

FIG. 2 is a block diagram showing a configuration of the NC device 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.
NC command processing program for performing processing according to each NC command of the commands, chuck control program 541, gripping claw position calculation program 542, gripping force calculation program 543, measurement dimension calculation program 544, tool correction amount correction program 545, measurement data setting Program 546, display unit 5
For example, there is a display control program for displaying characters and graphics on the display 8.

The chuck control program 541 performs processing of an NC command related to chuck opening / closing control and controls movement of the gripping claws 30. Gripping claw position calculation program 54
Reference numeral 2 denotes 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 central axis. The position of the gripping claw 30 is displayed and input by a diameter display, but is converted into a C-axis coordinate value and stored and managed inside the NC device 50. 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 spindle motor 4, the pitch of the scroll 17, 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 grip claw position on the display unit 58 is converted into a diameter value and displayed, and the input of the grip claw position is also based on the diameter value, so that it is easy for the operator to understand.

The gripping force calculation program 543 is a program for calculating the 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 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 measurement dimension calculation program 544 is a program for detecting the position of the gripping claw 30 when the workpiece is gripped by the chuck 15, and calculating the size of the gripping portion of the workpiece from the position of the gripping claw 30. Since the relationship between the position of the gripping claw 30 and the size of the workpiece changes due to a dimensional change due to wear or the like of the gripping claw 30, the relationship between the position of the gripping claw 30 and the size of the workpiece is stored as necessary. Try to fix it. The measurement size calculation program 544 calculates the size of the workpiece based on the relationship between the latest position of the gripper 30 and the size of the workpiece.

The tool correction amount correction program 545 determines the wear or loss of the tool based on the difference between the target size of the workpiece and the size actually measured by holding the chuck 15 and corrects the value of the tool correction amount of the tool. Or display a tool defect. Then, the measurement data setting program 54
Numeral 6 is a program for storing the position of the gripping claw 30 by teaching the relationship between the position of the gripping claw 30 and the size of the workpiece, and for storing the setting data for measurement input by the operator in the memory.

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 nonvolatile 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 unit 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 torque interval 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.

Further, an NC machining program memory 56, a chucking data memory 57, and a tool correction data memory 572 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 1 are relatively moved in the Z direction.
An NC machining program for performing machining by controlling movement in an axis (a direction parallel to the main axis) and an X axis (a direction orthogonal to the Z axis) is stored.

The chucking data memory 57 is a memory for storing a set of data for specifying various gripping conditions such as gripping force and gripping diameter input from a chuck setting screen as shown in FIG. The chucking data is set, for example, by the user for each type of workpiece.
The chucking data memory 57 stores not only data for specifying gripping conditions for processing for each parameter group No. but also chucking data for measurement 571 for specifying measurement / correction conditions for measurement. The tool correction data memory 572 is a memory for storing a tool correction amount for each tool. Since the tool edge wears as the machining time elapses, a tool correction amount is stored for each tool in order to correct a machining error due to the wear.

The CPU 51 is connected to input / output devices via a bus 52. As input / output devices, a display unit 58 for displaying characters and figures and an input unit 59 for an operator to input data are connected to the bus 52 via an interface circuit. CR is used as the display unit 58.
T, EL display panel, liquid crystal display, etc. can be used,
As the input unit 59, a keyboard, a touch panel integrated with the display unit 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 detected by a detector 412.
Is fed back to the amplifier 411 to maintain a predetermined rotation speed. The angular position of the main shaft 2 around the C axis is
Feedback is sent from the detector 412 to the C-axis / spindle controller 410, and the spindle 2 can be positioned at a desired angular position.

Similarly, the NC device 50 is connected to an X-axis motor 60 of the NC lathe via an X-axis positioning control unit 61 and an amplifier 62.
, And controls the relative movement of the workpiece and the tool rest in the X-axis direction (a direction orthogonal to the Z-axis direction). The rotation speed and rotation angle of the X-axis motor 60 are fed back to the amplifier 62 and the X-axis positioning control unit 61 via the detector 63, and the relative movement between the workpiece held by the chuck 15 and the tool rest in the X-axis direction is performed. Used for speed and position control. The functions of the Z-axis motor 70, the Z-axis positioning controller 71, the amplifier 72, and the detector 73 are the same as those for the X-axis, and the Z-axis direction of the workpiece and the tool rest (the direction parallel to the main axis direction).
To control the relative movement of

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, the PLC 500 also includes an actuator for driving the insertion unit 45, a sensor 48 for detecting whether the insertion unit 45 is at the insertion position or the removal position, and the like.
It is connected to the.

FIG. 3 shows an operation panel 510 of the chuck 15.
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 unit 58 of the NC device 50. This screen is
This is a screen for the machine tool maker to set the basic chuck parameters 551 or for performing maintenance on the machine tool. The user cannot change the basic chuck parameters 551 from this screen. 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. The cursor position can be changed by a cursor movement key (not shown), 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.

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 N (Newton).

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. The measurement torque limit value T5 is a torque limit value of the gripping claw 30 during the measurement operation. T1, T5
Is entered as a percentage of the maximum torque.

The C-axis command speed V1 is the C-axis moving speed at the time of high-speed movement of the gripping claw 30, and is, for example, the C-axis rapid feed speed. The C-axis command speed V2 is a C-axis moving speed when the gripping claw 30 moves at a low speed (during a gripping operation or the like). The measurement C-axis command speed V5 is a C-axis moving speed at the time of the measurement operation of the gripping claw 30, and is lower than the C-axis command speed V2. These V
The unit of 1, V2, V5 is rotation / minute, and is represented by the rotation speed of the main shaft 2.

The measured gripping force set by the measurement torque limit value T5 is generally much smaller than the gripping force during machining. The measured gripping speed specified by the measurement C-axis command speed V5 is generally a lower gripping speed than the gripping speed during processing.

As described above, in general, it is better to set the measured moving speed lower than the processing moving speed and set the measured gripping force smaller than the processing gripping force. Shock and strain applied to the object are reduced, and accurate dimensional measurement can be performed. Further, the smaller the measured gripping force is, the smaller the measured value can be measured without giving any deformation or distortion to the workpiece.

FIG. 5 is a diagram showing a chuck setting screen displayed on the display unit 58 of the NC device 50. This chuck setting screen is displayed by pressing the “setting” key of the function key from the chuck maintenance screen of FIG. When the "measurement" key of the function key is pressed from the chuck setting screen, the screen shifts to the simple measurement screen of FIG. Various chucking data stored in the chucking data memory 57 are displayed on the chuck setting screen. As these chucking data, one set of chucking data is stored for each type of workpiece (type of machining) and the like, and a plurality of sets of the chucking data are stored. The chucking data can be freely set by the user.

The chucking data will be described. The parameter group No. is a number assigned to a set of chucking data. The machining program No. is the program number (O number) of the NC machining program that uses this set of chucking data. The gripping force is a set value of the gripping force for gripping the workpiece. The setting unit is N (Newton). The grip diameter is a set value of the grip position of the workpiece. 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. The grip diameter, the shift point, and the retreat point are all values displayed in diameter.

An 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 chucking data can be performed by changing the cursor position using a cursor movement 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. 5, there is a cursor 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.

FIG. 6 is a diagram showing a simple measurement screen displayed on the display unit 58 of the NC device 50. This simple measurement screen is displayed by pressing the "measure" key of the function key from the chuck setting screen of FIG. On this simple measurement screen, the size of the workpiece can be measured by setting the chuck 15 to the measurement mode. The function of each function key displayed at the bottom of the screen will be described. The “measurement on / off” key is used to switch the operation mode of the chuck 15 to a measurement mode ON state in which the gripper 30 performs a measurement operation. Each time the "measurement on / off" key is pressed, the measurement mode is alternately switched between the "on" state and the "off" state.

If the measurement mode is "ON" (ON), "measurement mode ON" is displayed at the upper center of the screen, and if the measurement mode is "OFF", "measurement mode OFF" is displayed. Further, in the measurement mode “ON” state, the measurement torque limit value T5 and the measurement C-axis command speed V5 are valid, and the workpiece is gripped at a predetermined measurement gripping force and measurement gripping speed. FIG.
Is a measurement mode ON state.

The "correction" key will be described in detail later.
After the dimension of the workpiece is measured, the tool correction amount is corrected. The "enter" key is used to set the data input by pressing after inputting the setting data on the screen. The “delete” key is used to delete all setting data on the screen. The "Teach" key
As will be described later in detail, a reference workpiece (reference gripped object) having a known size is gripped by the chuck 15 and stored in the NC device 50 by teaching the relationship between the position of the gripping claw 30 and the size of the workpiece. It is for. The "return" key is for returning to the chuck setting screen from which this screen was called.

On the simple measurement screen, setting data for the measurement operation and measured value data of the workpiece are displayed.
The “measurement value” at the top displays a measurement value (diameter value) of the dimension of the workpiece when the workpiece is gripped in the measurement mode. Further, a display indicating whether or not the measured value is within the dimensional tolerance of the target size is displayed on the right side of the measured value data. If it is within the dimensional tolerance, “OK” is displayed as shown in FIG. If it is out of the dimensional tolerance to the small diameter side, "-N
G ", and" + NG "if it is out of the large diameter side.
Further, "---NG" is displayed if it is off to the small diameter side to indicate a tool defect, and "++ NG" is displayed if it is off to the large diameter side.

The "correction input amount" is a value obtained by calculating a difference between a target machining diameter, which is a target dimension of a workpiece, and the above-described measured value. The NC device 50 stores, in the tool correction data memory 572, a tool correction amount for making each tool coincide with the actual position of the tool edge in association with the tool number. The data of the correction input amount indicates an amount to correct the tool correction amount. Further, the tool life can be determined based on the cumulative value of the tool correction amount. Next "tool number"
Is the tool number of the tool used for machining the workpiece to be measured. The tool correction amount for this tool number is to be corrected. The next “correction dead zone” is an error range for preventing the correction of the tool correction amount from being performed even if instructed.
If the magnitude of the correction input amount is equal to or smaller than the magnitude of the correction dead zone, the automatic correction of the tool correction amount is not executed even if instructed.

The next “target machining diameter” is a diameter value indicating a target dimension of the workpiece. The following "dimensional tolerance +" (+ side dimensional tolerance) and "dimensional tolerance-" (-side dimensional tolerance) are the dimensional tolerance on the large diameter side and the dimensional tolerance on the small diameter side with respect to the target processing diameter.
As described above, the measured value is the maximum allowable dimension (target machining diameter and +
If the measured value exceeds the sum of the side dimensional tolerance, it becomes "+ NG" and the measured value becomes the minimum allowable dimension (the sum of the target machining diameter and the negative dimensional tolerance).
Is exceeded, it becomes "-NG". Next “Standard Workpiece Diameter”
Is used for inputting the measured dimensions of the reference workpiece as the reference workpiece when grasping the reference workpiece and teaching the relationship between the position of the gripper and the dimension of the workpiece.

The next "tool defect determination allowable value" is an allowable value for determining a tool defect such as a tool defect based on a difference between a target machining diameter and a measured value. As described above, “−−NG” when the measured value deviates from the target machining diameter to the small diameter side beyond the tool defect determination allowable value, and “−−NG” when the measured value exceeds the tool defect judgment allowable value to the large diameter side. ++ NG "is displayed.

Each data other than the measured value and the correction input amount displayed on the simple measurement screen can be changed and set. The cursor position can be changed by a cursor movement key (not shown), and each data can be input and changed and set. The line at the cursor position is underlined. In FIG. 6, the cursor is on the data line of the tool number,
This value is configurable.

Next, a description will be given of an operation in a case where an operator manually performs measurement. First, initial settings in the measurement operation are performed. For that purpose, the following operation is performed. The mode switch 511 is switched to the chucking mode.
The setup opening / closing switch 514 is pressed to enter the “ON” state (setup opening / closing state). The inside / outside tightening switch 512 is selected in a desired direction, and the grip release switch 513 is set as the tightening direction. In the setup opening / closing state, the foot switch 501 is operated to move the gripping claw 30 to a position having a predetermined gap with respect to the workpiece.

Next, the simple measurement screen shown in FIG.
By operating the "measurement on / off" key, the operation mode of the chuck 15 is set to the "measurement mode ON" state. However, when the workpiece is gripped by the chuck 15, the workpiece cannot be gripped with the measured gripping force and the measured gripping speed.
After moving 0 in the loosening direction to remove the workpiece, the measurement mode is turned on. Then, the measurement torque limit value T5 and the measurement C-axis command speed V5 set by the software basic parameters are selected, and the gripping force and the gripping speed of the chuck 15 are fixed to the measured gripping force and the measured gripping speed.

Then, the grip release switch 513 is set to the tightening direction, and the foot switch 501 is operated to cause the chuck 15 to grip a workpiece whose dimensions have been measured in advance or a reference workpiece (reference workpiece) such as a master gauge. . At this time, the gripping claw 30 moves in the tightening direction at the measured gripping speed while operating the foot switch 501, and stops moving when the force gripping the reference workpiece reaches the measured gripping force.

Next, on the simple measurement screen, necessary data for the reference workpiece diameter, target processing diameter, + side dimension tolerance, -side dimension tolerance, and tool number are input. And "Teach"
When the key is pressed, the position of the gripping claw 30 at that time is stored, and the position of the gripping claw 30 and the size of the workpiece are determined based on the input reference work diameter and the stored position of the gripping claw 30. Is determined and stored. Note that, even if the "teach" key is pressed while the essential data such as the reference work diameter has not been input and is blank, a warning display prompting data input is displayed and the teaching operation is not performed.

When the teaching operation is completed, the grip release switch 513 is set to the loosening direction, and the grip switch 30 is loosened by operating the foot switch 501. In this case, while the foot switch 501 is being operated in the setup opening / closing state, the grip claw 30
Continues to move, and when the operation of the foot switch 501 is stopped, the movement of the gripping claw 30 stops. During this movement, the gripper 30
Are converted into workpiece diameter value data and added or subtracted.

Note that even if an attempt is made to loosen the gripping claw 30 with the grip release switch 513 and the foot switch 501 while the essential data such as the reference work diameter and the like are not input and blank, a warning message prompting data input is displayed. No loosening action is performed. After removing the reference workpiece, the "measurement on / off" key is operated to set the operation mode of the chuck 15 to the "measurement mode OFF" state. Thereby, the chuck 1
5 returns to the setup opening / closing state.

The initial setting in the above measuring operation is performed when the power of the machine tool is turned on, when the setup is changed, and when necessary. When the gripping claws are so-called raw claws and the raw claws are cut in accordance with the workpiece diameter, the initial setting is performed after cutting the gripping claws, and the relationship between the gripping claw position and the workpiece size is updated. In the right relationship. In addition,
In the case where the gripping claws are hardly worn, such as when the gripping portions of the gripping nails are subjected to quenching processing, the initial setting data is stored in the non-volatile memory, and the power of the machine tool is turned off. At times, the initial setting data may be held. In this case, the operation of the initial setting need only be performed at a very low frequency, such as once a week or once a month.

When actually measuring a workpiece, a simple measurement screen is called, and the "measurement on / off" key is operated to set the chuck 15 in the measurement mode ON state. Thereby,
The gripping force and the gripping speed of the chuck 15 are fixed to the measured gripping force and the measured gripping speed set by the software basic parameters. Then, the grip release switch 513 is set to the tightening direction, and the foot switch 501 is operated to operate the grip claw 30.
Is moved, and the workpiece is gripped by the gripping claws 30. Even during the movement of the gripping claw 30, the position of the gripping claw 30 is converted into workpiece diameter value data and is added or subtracted. When the force for gripping the workpiece reaches the measured gripping force, the gripping claw 30 stops.
On the simple measurement screen, the diameter value of the workpiece is displayed in the data line of the measurement value. Further, it is determined whether or not the measured value is between the maximum allowable dimension and the minimum allowable dimension, and the determination result is displayed on the right side of the diameter value.

Further, the difference between the target machining diameter and the measured value is displayed in the correction input amount. At this time, when the "correction" key is pressed, the tool correction amount corresponding to the tool number is corrected by the correction input amount, and the tool correction amount is adjusted to the measured value. In addition,
In the manual operation of correcting the tool correction amount, the correction dead zone is ignored, and the operation of correcting the tool correction amount is always performed. When the measurement is completed, the grip release switch 513 is set to the release direction, and the foot switch 501 is operated to loosen the grip claw 30. After removing the workpiece,
Operate the “OFF” key to turn off the measurement mode of chuck 15
State.

Next, the operation in the case where the measurement is automatically performed according to the NC command in the NC machining program will be described.
The initial setting in the measurement operation is almost the same as the manual setting. The simple measurement screen of FIG. 6 is called from the chuck setting screen of the parameter group No. for gripping the workpiece at the time of machining, and the teaching operation using the reference workpiece and the setting of each data are performed. This initial setting may be appropriately performed when necessary. Data set from this chuck setting screen,
The data set from the simple measurement screen is stored as a set under the parameter group number. Then N
An NC command for instructing selection of a parameter group No. and automatic measurement is put in an appropriate place in the C machining program, and automatic measurement is performed by executing the NC machining program. As an NC command for instructing automatic measurement, a macro call using a G code, an M code, or the like (for example, M78)
9) can be used.

When an NC command for instructing automatic measurement is executed, the gripping claw 30 is moved from the evacuation point to the shift point at a high-speed rapid traverse, and from the shift point until the measured gripping force is reached at the measured gripping speed. . Then, the size of the workpiece is measured by being gripped by the chuck 15, and the acceptability of the workpiece is determined based on the dimensional tolerance of the target processing diameter. If the measured value is out of the range of the dimensional tolerance (+ NG, -NG), the workpiece is ejected as a defective product and returns to the beginning of the NC machining program. Further, when the difference between the measured value and the target machining diameter exceeds the allowable value for the tool defect judgment (++ NG, -−N
G) is notified of tool breakage. Then, the correction of the tool correction amount is also automatically performed. If the correction input amount is larger than the correction dead zone, the correction input amount is added to the tool correction amount to correct the tool correction amount. The tool life is determined based on the cumulative value of the tool correction amount.

In the automatic measurement according to the NC command, the gripping operation may be automatically repeated a plurality of times, and the average value of the dimension measurement values obtained by each grip may be calculated and used as the measurement value.
Even in the automatic measurement by the NC command, the gripping force and the gripping speed of the chuck 15 are fixed to the measured gripping force and the measured gripping speed set on the software basic parameter screen. That is, the measurement chucking data 571 is selected. The correction of the tool correction amount is also performed for the tool number set on the simple measurement screen.

The automatic measurement according to the NC command is actually performed during a plurality of processes. Next, a procedure of automatic measurement between a plurality of processes will be described. FIG. 7 is a diagram showing a case of an NC lathe having a single main shaft. First, as shown in FIG. 7A, the workpiece W is
Performs the cutting process in the first step. Next, as shown in FIG. 7B, the workpiece W is released from the chuck 15 while holding the workpiece W in the reversing device H, and the orientation of the workpiece W is reversed by the reversing device H. That is, the processing portion of the workpiece W in the first step is directed to the chuck 15 side.

Next, as shown in FIG. 7C, a parameter group No for gripping the gripped portion Wa of the workpiece W is selected by the NC command. Subsequently, automatic measurement by the chuck 15 is performed. At this time, the gripping force and the gripping speed of the chuck 15 are fixed to the measured gripping force and the measured gripping speed for the measurement operation set on the software basic parameter screen. That is, the gripping claw 30 moves at a rapid traverse from the retreat point to the shift point, moves at the measured gripping speed from the shift point,
When the measured gripping force is reached, the movement of the gripper 30 is stopped. By this automatic measurement, the pass / fail judgment of the size of the processing portion in the first step, correction of the tool correction amount, and the like are performed. Next, FIG.
As shown in (d), the gripping force of the chuck 15 that grips the gripped portion Wa of the workpiece W is set as the gripping force for processing set in the selected parameter group No.
, And the cutting process of the second step is performed by the tool B.

FIG. 8 is a diagram showing a procedure of automatic measurement on an NC lathe having two main spindles facing each other. In this NC lathe, the workpiece is gripped by the chuck 15a on the first spindle side to perform the processing in the first step, and then the workpiece is delivered to the chuck 15b on the second spindle side and the workpiece is transferred to the chuck 15b on the second spindle side. A two-step process is performed. First, as shown in FIG. 8A, the workpiece W1 is gripped by the chuck 15a on the first spindle side, and the first step of cutting is performed by the tool B1.

Next, as shown in FIG. 8B, the second spindle is moved and automatic measurement is performed by the chuck 15b on the second spindle side. A parameter group No for gripping the gripped portion Wa1 of the workpiece W1 is selected. And the chuck 15b
Automatic measurement by. That is, since the gripping claw 30 moves with the measured gripping speed and the measured gripping force from the shift point to the gripping position, the workpiece W1 is gripped with the chuck 15b as the measured gripping force and the measured gripping speed for the measuring operation before the delivery. Then, the dimensions of the processed part in the first step are measured. By this automatic measurement, the pass / fail judgment of the size of the processing portion in the first step, correction of the tool correction amount, and the like are performed. Then, the workpiece W1 is gripped by using the gripping force of the chuck 15b as the gripping force for processing set in the selected parameter group No., and the chuck 15a releases the workpiece W1. with this,
The workpiece W1 is delivered to the chuck 15b.

Next, as shown in FIG. 8C, the second spindle is moved to the processing position, and the workpiece W1 is subjected to the second step of cutting with the tool B2. At the same time, a new work W2 is gripped by the chuck 15a, and the cutting process of the first step is performed by the tool B1.

FIG. 9 is a diagram showing another example of automatic measurement on an NC lathe having two opposing main spindles. This is an example of measuring the inner diameter of a workpiece. Also in this case, the workpiece is gripped by the chuck 15a on the first spindle side to perform the processing in the first step, and then the workpiece is moved to the chuck 1a on the second spindle side.
5b, and the second spindle is processed on the second spindle side.
First, as shown in FIG. 9A, the workpiece W is gripped by the chuck 15a on the first spindle side, and cutting in the first step is performed. In this first step, outer diameter processing and inner diameter processing are performed as shown.

Next, as shown in FIG. 9B, the second spindle is moved and automatic measurement is performed by the chuck 15b on the second spindle side. That is, before the delivery, the chuck 15
Assuming that b is a measurement gripping force and a measurement gripping speed for the measurement operation, the inner diameter measurement part 301 of the gripping claw 30b grips the inner diameter processing part of the workpiece W from the inside, and measures the dimension of the inner diameter processing part in the first step. . In this example, the processing part Wb of the workpiece W
1 is not gripped for machining, but the retraction point, shift point, gripping force, etc., as a dummy
Set to. By selecting this parameter group No and issuing an instruction for automatic measurement, the gripping claw 30 moves at a measured gripping speed from the evacuation point to the shift point at rapid traverse and from the shift point to the gripping position at a measured gripping speed. Upon reaching, the movement of the gripping claw 30 is stopped. By this automatic measurement, the first
Judgment of pass / fail of the size of the inside diameter machining portion in the process, correction of the tool correction amount, and the like are performed.

Next, as shown in FIG.
Of the parameter group No. for gripping the gripped portion Wb2 of FIG. That is, the workpiece W is gripped from the outer peripheral side by using the gripping force and the gripping speed of the chuck 15b as the gripping force and the gripping speed for processing.
5a releases the workpiece W. Thus, the workpiece W is delivered to the chuck 15b. The subsequent processing in the second step
This is performed in the same manner as that shown in FIG. When the workpiece W is gripped from the outer peripheral side by the chuck 15b, it is also possible to automatically measure an outer diameter processing portion of the workpiece W.

As described above, when the workpiece is gripped again between the first step and the second step, the dimensions of the machined portion in the first step are automatically measured. The required time is significantly reduced and automatic measurements can be made without increasing the overall processing time. By the automatic measurement, it is possible to automatically determine whether or not the processing dimension is acceptable, automatically correct the tool correction amount, determine the tool life, determine a tool defect such as a tool defect, and the like. In addition, a dedicated measuring device for measuring the dimension of the workpiece is not required, and an increase in cost of the machine tool can be suppressed. Further, since the size of the workpiece is measured by gripping the chuck, accurate dimension measurement can be performed without being affected by thermal displacement of the base of the machine tool.

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.

Also, a group number may be assigned to the simple measurement screen, and data of a retreat point, a shift point, and a grip diameter may be input on this screen. When performing automatic measurement, the group number may be selected. . In addition, macro call commands for automatic measurement include target machining diameter, + side dimensional tolerance,-
Data such as side dimensional tolerance, tool number, retreat point, shift point, and grip diameter may be given as arguments.

[0090]

The present invention is configured as described above, and has the following effects.

Since the dimensions of the workpiece are measured by the chuck used when processing the workpiece, a dedicated measuring device for measuring the dimensions of the workpiece is not required, and an increase in the cost of the machine tool is suppressed. However, manual measurement and automatic measurement of the size of the workpiece can be performed. By the manual measurement or the automatic measurement, it is possible to determine whether or not the processing dimension is acceptable, correct a tool correction amount, determine a tool life, determine a tool defect such as a tool defect, and the like. Further, since the dimensions of the workpiece are measured by gripping the chuck, accurate dimension measurement can be performed without being affected by the thermal displacement of the base of the machine tool.

Since the position of the gripping claw of the chuck is detected based on the rotation angle position of the drive motor, the size of the workpiece can be easily measured without increasing the cost without adding a special detector for measuring the size. It can be carried out.

Since the known size is input while the reference workpiece having the known size is gripped by the gripping claws, and the relationship between the gripping claw position and the workpiece size is taught, the gripping position of the gripping claw may be worn. The relationship between the position of the gripping claw and the size of the workpiece can be maintained correctly.

Since the pass / fail judgment of the workpiece is made based on the measured dimensions of the work, the target dimensions and the dimensional tolerances, the result of the pass / fail judgment is displayed so that the worker can see at a glance whether the work is good or bad. It is also possible to automatically sort workpieces according to quality.

Since the tool correction amount is corrected based on the difference between the target dimension and the actually measured dimension of the workpiece, the tool correction amount of the working tool can always be corrected to a correct value, and the processing accuracy is improved. Further, the tool life can be determined based on the accumulated value of the tool correction amount.

After the workpiece is gripped and processed according to the gripping conditions for processing, the processing portion of the workpiece is gripped under the gripping conditions for measurement to measure the dimensions. Accurate dimensional measurement can be performed under optimal gripping conditions for dimensional measurement. Further, since the dimensions of the workpiece are measured by gripping the chuck, accurate dimension measurement can be performed without being affected by the thermal displacement of the base of the machine tool.

Since the measurement moving speed is set to be smaller than the processing movement speed and the measurement gripping force is set to be smaller than the processing gripping force, the impact or distortion applied to the workpiece from the gripping claws at the time of measurement is reduced. It becomes smaller and accurate dimension measurement becomes possible.

When the workpiece is re-gripped during the transition from the processing of the first step to the processing of the second step, the dimension measurement of the processing portion in the first step is performed. The required time is significantly reduced and dimensional measurements can be made with little increase in overall machining time.

[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 a simple measurement screen displayed on a display unit.

FIG. 7 is a diagram showing a procedure of automatic measurement on an NC lathe having a single main spindle.

FIG. 8 is a diagram showing a procedure of automatic measurement on an NC lathe having two main spindles facing each other.

FIG. 9 is a diagram showing another example of automatic measurement on an NC lathe having two opposing main spindles.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Headstock 2 ... Spindle 4 ... Spindle motor 5 ... Rotor 6 ... Stator 7 ... Case 8 ... Cooling path 9 ... Nut 10 ... Spindle end 12 ... Face plate 15 ... Chuck 17 ... Scroll 19 ... Scroll groove 20 ... Body part 21 ... 1st member 22 ... 2nd member 25 ... master jaw guide groove 26 ... master jaw 28 ... scroll teeth 30 ... gripping claw 40 ... chuck fixing means 41 ... positioning hole 42 ... positioning member drive mechanism 43 ... positioning member 44 ... piston 45 ... Insertion part 46 ... Cylinder 47 ... Pressure fluid path 48 ... Sensor 50 ... NC device 60 ... X-axis motor 70 ... Z-axis motor 510 ... Operation panel 511 ... Mode changeover switch 512 ... Inside / outside tightening changeover switch 513 ... Grip release changeover switch 514 ... Setup open / close switch B, B1, B2 ... Tool H ... Reversing device W, W1, W ... workpiece 15a, 15b ... chuck 30b ... gripping claws 301 ... internal diameter measurement section

Claims (9)

[Claims] An electric chuck for gripping a workpiece by a gripping claw (30) of a chuck (15) supported on a frame provided on a base of the machine tool and measuring the dimension of the workpiece. The chuck (15) grips a workpiece by opening and closing the gripping claw (30) by a drive motor (4) capable of position control, and grips the gripped workpiece with a processing tool. A procedure for storing a relationship between a position of the gripping claw (30) and a workpiece size; and a step of storing a predetermined processing portion of the workpiece processed by the machine tool with the gripping claw (30). 30) gripping the workpiece under predetermined gripping conditions, and obtaining an actual measurement dimension of the processing portion from the position of the gripping claw (30) at that time. 2. The method according to claim 1, wherein the position of the gripping claw (30) is detected by a rotation angle position of the drive motor (4). A method for measuring workpiece dimensions using an electric chuck. 3. A method for measuring a workpiece size by an electric chuck according to claim 1, wherein the relationship between the position of the gripping claw (30) and the workpiece size is stored. The procedure includes a procedure of grasping a reference grasped object of a known size by the grasping claw (30), and a procedure of inputting a known dimension of the reference grasped object in a state where the reference grasped object is grasped. A method for measuring workpiece dimensions using an electric chuck. 4. A method for measuring a workpiece size using an electric chuck according to claim 1, wherein a step of inputting a maximum allowable dimension and a minimum allowable dimension of the machining portion is provided. A method for measuring a workpiece size using an electric chuck, comprising: a step of performing a pass / fail determination of a workpiece based on a dimension, the maximum allowable dimension, and the minimum allowable dimension. 5. A method for measuring a workpiece size by an electric chuck according to claim 1, wherein: a step of inputting a target dimension of the processing portion; and a tool for processing the processing portion. A method of measuring a workpiece dimension using an electric chuck, comprising: a step of inputting a tool correction number of the above-mentioned; . 6. A chuck (15, 15a, 1) supported by a frame provided on a base of a machine tool.
5b) A method for measuring the size of a workpiece by an electric chuck for measuring the dimension of the workpiece (W, W1) by gripping the workpiece with the gripping claws (30, 30b) of the chuck (15, 15a, 15b). ) Is for gripping a workpiece by opening and closing the gripping claws (30) by a drive motor (4) capable of controlling the position, moving speed and gripping force, and processing the gripped workpiece with a processing tool. The workpiece (W, W1) is gripped by the gripping claws (30) at a predetermined processing moving speed and processing gripping force suitable for processing the workpiece (W, W1). And the workpiece (W, W
A procedure for performing a predetermined processing on 1); a predetermined measurement moving speed and a measurement gripping force suitable for measurement of a predetermined processing portion of the workpiece (W, W1) processed by the machine tool; A procedure of gripping with the gripping claws (30, 30b) of the chuck (15) or another chuck (15b), and obtaining an actual measurement size of the processing portion from the position of the gripping claws (30, 30b) at that time; A method for measuring a workpiece size using an electric chuck having 7. The method for measuring the size of a workpiece using an electric chuck according to claim 6, wherein the moving speed for measurement is set to be lower than the moving speed for machining, and the gripping force for measurement is used for the machining. A method for measuring workpiece dimensions using an electric chuck that is set smaller than the gripping force. 8. A method for measuring a workpiece size by an electric chuck according to claim 6, wherein the workpiece (W, W1) ), The gripping claws (30, 30) at a predetermined processing moving speed and processing gripping force suitable for processing.
b) A method for measuring the size of a workpiece using an electric chuck, comprising the steps of gripping the workpiece (W, W1) and processing the workpiece (W, W1) in the next step. 9. A method for measuring the size of a workpiece by an electric chuck according to claim 6, wherein the gripping claws (30, 30)
(b) a method of measuring a workpiece size using an electric chuck, comprising: a procedure of gripping the reference workpiece; and a step of inputting a known dimension of the reference workpiece while gripping the reference workpiece.