JPH0283144A - Monitoring method for work coordinate position by programmable tail stock - Google Patents

Abstract

PURPOSE:To improve reliability by moving a tail stock equipped with a center by controlling a screw by its rotation by a control device, and measuring positional errors by detecting the position where the center is brought into contact with a work one end. CONSTITUTION:A tail stock 1 equipped with a center 2 is moved by advancing and retreating in the axial direction with the rotary control of the screw 6 driven by its rotation by a servomotor 5, and the positional error is measured with the position where the center 2 is brought into contact with one end of a work 3 being detected. A pressing means 7 is provided for pressing the center 2 to the work 3, and in the case of its abuttment with the work 3 a change valve 14 is switched and it is made in low pressure in advance, the positional signal of the case of the center 2 being abutted is changed to high pressure as a skip signal and the work 3 is pressed. In this case the screw 6 is retreated at the time the work 3 is surely chucked, so a limit switch 17 is not actuated and it is judged as normal. Consequently the work 3 end dimensional error and chucking mistake can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a workpiece coordinate position monitoring method using a programmable tailstock. More specifically, when the programmable tailstock brings the workpiece into contact with the center, this signal is captured as a skid/stick signal, the position detection signal of one end of the workpiece is stored, and the workpiece end dimension is determined by comparing it with a preset reference value. The present invention relates to a workpiece coordinate position monitoring method using a programmable tail stock that automatically checks errors in the workpiece coordinate position caused by errors in the workpiece, chuck errors, and the like.

[Prior Art] - A programmable tailstock for JR trains is fed in the W-axis direction (parallel to the Z-axis) by a ball screw that is driven and controlled by a servo motor. The fed tailstock is moved a predetermined distance in the direction of the spindle axis in accordance with various preset workpiece lengths and positioned, and is then programmably controlled to press and support one end of the workpiece at the center.

[Problems to be Solved by the Invention] This type of tailstock presses and clamps the workpiece after being moved a predetermined distance by a programmed amount for various workpiece lengths. In this case, dimensional errors due to errors in the length of the workpiece material or inclination due to chucking errors of the chuck are not taken into consideration when clamping by the center. Therefore, if the workpiece is measured immediately after machining and the machining error is found, the workpiece will be reprocessed, or if the error is found by measurement performed several steps later, reprocessing will not be possible. This often results in most of the waste being disposed of.

This not only wastes materials, but also reduces the reliability of the machining accuracy of the machine tool and impedes productivity.

Therefore, an object of the present invention is to use a programmable tailstock that can check for errors in workpiece length dimensions, chuck mistakes, etc. each time the programmable tailstock comes into contact with the workpiece, when pressing a workpiece of a predetermined length with the programmable tailstock. The present invention provides a method for monitoring the coordinate position of a workpiece.

[Means for Solving the Problems 1] In order to achieve the above objects, the present invention takes the following measures.

The first means is a programmable table stock comprising a tail stock with a center, a screw for driving the tail stock, a servo motor for rotationally driving the screw, and a numerical control device for controlling the 7-votor. , a workpiece coordinate position using a programmable tail stock, characterized in that the screw is rotationally controlled by the control device to move it forward and backward in the axial direction, and the position where the center contacts one end of the workpiece is detected to measure the positional error of the workpiece. This is a monitoring method.

The second means includes, in the first means, a pressing means having a switching valve communicating with a hydraulic power source in order to drive the screw and press the center against the workpiece, and the switching valve when in contact with the workpiece. is switched in advance to a low pressure, the screw is rotated and a position detection signal when the center comes into contact with the end surface of the workpiece is taken in as a skip signal, and the skip signal is used to switch the switching valve to a high pressure and the pressure is applied via the screw. This coordinate position monitoring method using a programmable tail stock is characterized in that the workpiece is supported under pressure, the workpiece position detected by the skip signal is compared with a preset reference value, and a position error at one end of the workpiece is measured.

[1] According to the coordinate position monitoring method using a programmable tailstock according to the present invention, the tailstock is advanced from its original position in response to a start command. As a result of this forward movement, the tailstock is stopped from rapidly moving slightly before one end of the workpiece. The screw is rotated and moved forward in the axial direction to bring the center of the tailstock into contact with one end of the workpiece. This contact is taken out as a skip signal and the workpiece coordinate position is detected. This coordinate position is compared with a preset setting value to determine whether one end of the workpiece is within an allowable value.

[Embodiment 1] Hereinafter, an embodiment of a workpiece coordinate position monitoring method using a programmable tailstock according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows an overall configuration diagram of a programmable tail stock according to the present invention. The tailstock main body 1 is a known one that slides on the bed of a machine tool in the W-axis direction. The center 2 can be hydraulically or screw fed so as to be movable in the W axis direction within the tail stock 1, and is used to press the center hole of the workpiece 3. This drive is performed automatically or semi-automatically.

A workpiece 3 is held by a chuck 4.

The servo motor 5 is a servo motor whose rotation is controlled by a known NC control device C (not shown).

The servo motor 5 is a driving means for driving the ball screw 6. Furthermore, the pressing means 7 is a hydraulic unit that feeds the ball screw 6 in the W-axis direction.

The pressing means 7 includes a cylinder case 8, a hollow shaft 9 rotatably driven by the servo motor 5 inside the cylinder case 8, a piston 11, and the like. A timing pulley and a timing belt are connected to one end of the hollow shaft 9.

One end of the ball screw 6 is attached to the other end of the hollow shaft 9 with a key 12.
It is connected by. The ball screw 6 has a piston 11,
One end is supported by a bearing held by the cover 10. The piston 11 and cover 10 are screwed together with bolts to provide a preload to the bearing. A boss IOA is formed at one end of the cover 10. Further, a hydraulic circuit 15 is connected to one side of the piston 11 in the cylinder case 8 so that hydraulic pressure from a hydraulic pressure (hereinafter referred to as hydraulic pressure) source 13 is supplied via a switching valve 14 .

Also, the center 2 is in contact with one end of the workpiece 3, and the piston 1
The cover 10 is fixed to the piston 11 when the piston 1 moves backward.
The position of the boss IOA formed in the limit switch 16
Detected by Further, the limit switch 17 detects when the piston 11 is positioned at the leftmost position due to hydraulic pressure.

艷-1 The programmable tailstock configured as described above performs the following operations. In other words, the first movement is
Each step will be explained based on the flowchart shown in the figure. First, as a preparation, set the position for pressing. Supplying hydraulic pressure from the hydraulic source 13 to the cylinder case 8 via the switching valve 14,
The piston 11 is moved forward. When the piston 11 moves forward, the hydraulic pressure supply to the cylinder case 8 is cut off by the switching valve 14, and the pressure inside the cylinder case is made into a residual pressure. The center 2 of the tail stock 1 is manually moved to a predetermined workpiece and pressed against one end of the workpiece 3, thereby setting the pressing position (coordinate system setting).

For example, input and set the QO (O indicates the coordinates of the pressed position, and usually the end of the workpiece is O). The programming method is a custom macro (a program that can be defined by the user), for example, as follows.

Goo BlO,O G x x B D Q T S Ordinary Cannibal Program 28DO OOB The meaning of GOOBIO,O in the above program is an example of fast forwarding and stopping at a position where the workpiece is approached 10 mm before the end face. In B- of GXX, input the position of pressing the center 2 against the workpiece. D- has work 3
The pressing force calculated from the dimensional error of the material, etc. is an allowable error dimension that indicates the allowable error range. Q is used to input whether or not to issue a re-chucking command, since there may be an error in pressing due to a gripping error in the chuck 4 or the like. For example, if it is 1, there is a re-chucking command, and if it is 0, there is no re-chucking command.

T- indicates the time during which the jaws of the chuck 4 are open during the rechucking command operation. After this time has elapsed, the chuck performs a closing operation.Similarly, at the time of a rechucking command operation, S 2 indicates the time for the jaws of the chuck 4 to grip the workpiece 3.

After this time has elapsed, that is, after the chuck has completely held the workpiece 3, the operation of the next block begins.

In response to a start command of the custom macro program, hydraulic pressure is supplied from the hydraulic source 13 to the cylinder case 8 by the switching valve 14, and the piston 11 is moved forward. Move the tail stock 1 forward from the original position toward the chuck 4 (Ps)
.

As a result of this forward movement, the tail stock 1 is stopped slightly (for example, 10 mm) before one end of the workpiece 3 after rapid movement. In this case, by switching the switching valve 14 communicating with the hydraulic power source 13,
Although the hydraulic pressure supply to the inside of the cylinder case 8 is cut off, residual pressure still exists inside. Therefore, in the next step, the tail stock l is axially moved at the set feed rate F- by rotation of the ball screw 6 by the servo motor 5 (P2).

The tip of the center 2 is inserted into the center hole of the workpiece 3. Furthermore, if the center 2 is moved further forward by controlling the rotation of the ball screw 6 even though it is in contact with the workpiece 3, the tail stock l cannot move forward any further.

However, after the center 2 and workpiece 3 come into contact, the ball screw 6
The piston 11 moves backward by the amount of rotation.

The limit switch 16 commands this retreat to skip (a function that interrupts the rest of this command and executes the next block when a skip signal is input from the outside during an axis movement command).
Detect the signal (P3).

This movement continues until the piston 11 can move (P4). However, if the skip signal cannot be detected even within this moving range, a typical alarm signal will be issued (
P4, Ps).

Therefore, the position where this skip signal is output is stored as the position of one end of the workpiece 3 from the machine origin.

Next, the switching valve 14 is switched by the M2S command in the macro command to introduce oil pressure into the cylinder gauge 8 and drive the piston 11. At this time, when the piston 11 advances and moves to the most forward end position, the limit switch 17 detects (
P7). If the center 2 and the workpiece 3 are in normal contact, the limit switch 17 should not operate, but if not, the limit switch 17 will operate. Since the contact between the center 2 and the workpiece 3 was detected in step P3, the piston 11 should not move if the workpiece 3 is normal.

However, even if the limit switch 17 is actuated, the alarm is not immediately activated, and if a re-chucking command is issued, the re-chucking operation is started (P8). In the rechucking operation, the piston 11 is freed again, the workpiece 3 is gripped by a robot hand, the jaws of the chuck 4 are opened, and the jaws are operated again to grip the workpiece 3. The above operation is performed again for re-chucking, and the signal detected by the limit switch 16 is taken in as a skip signal (P7>.

Compare and calculate whether this coordinate position is within the allowable error range (P9) against a preset reference value, and if it is outside the range, it is assumed that the workpiece size or chuck is defective and an alarm is issued (Pro). . If the power goes out during processing,
The programmable tailstock operates according to the flowchart shown in FIG.

That is, the block skip function (invalidates block commands containing /slashes) is used to restart the flow without performing the operations described above.

[Other Embodiments] In the above embodiment, the limit switch 16 detects when the center hits the workpiece and the boss 10 retreats, and the hydraulic pressure is turned to O.
I set it to N. However, the boss 1° did not retreat,
A set value may be determined based on the rotation of the servo motor 5, and the oil pressure may be turned on when this set value is reached. After this,
This is the same operation as above. In the above embodiment, hydraulic pressure was applied to the pressing means, and the pressing means was not necessarily necessary.
The pressing force between the workpiece 3 and the center 2 may be determined by using a spring, and the contact position may be detected by detecting the torque of the servo motor 5, or by a sensor detecting the pressing force between the workpiece 3 and the center 2.

[Effects of the Invention] As is clear from the above-mentioned embodiments, according to the present invention, by using a programmable tail stock to check errors in workpiece end dimensions and check chucking errors,
The reliability of machining can be improved, and productivity can also be improved. As a result, setup time can also be shortened.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a programmable tail stock showing an embodiment of the present invention, FIG. 2 is an operation diagram, and FIG. 3 is an operation diagram when restarting after power is turned off.

Claims (1)

[Claims] 1. A programmable table stock consisting of a tail stock with a center, a screw that drives the tail stock, a servo motor that rotationally drives the screw, and a numerical control device that controls the servo motor. , the control device rotationally controls the screw to move it forward and backward in the axial direction;
A method for monitoring the coordinate position of a workpiece using a programmable tail stock, characterized in that the position of the center in contact with one end of the workpiece is detected and the positional error of the workpiece is measured. 2. In the description of item 1, a pressing means having a switching valve connected to a hydraulic power source is provided in order to drive the screw and press the center against the workpiece, and when the switching valve comes into contact with the workpiece, the switching valve is set in advance. The switching valve is switched to a low pressure, the screw is rotated, and the position detection signal when the center comes into contact with the end face of the workpiece is taken in as a skip signal, and the skip signal is used to switch the switching valve to a high pressure, and the workpiece is moved through the screw. A coordinate position monitoring method using a programmable tail stock, characterized in that the position of the workpiece detected by the skip signal is compared with a preset reference value, and the position error of one end of the workpiece is measured.