JP2919754B2 - Backlash measurement and correction device for spherical or circular surface machining - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an apparatus that measures the amount of backlash during cutting of a spherical surface or an arc surface created by axis control in a machine and performs correction at the time of subsequent machining.

[0002]

2. Description of the Related Art Conventionally, since a ball screw is almost used in a feed shaft drive system in a machine tool such as an NC lathe, an error (backlash) occurs between a command position and an actual position due to backlash when the feed direction is reversed. Occurs. In order to remove the processing dimension error due to the backlash, various backlash removing methods or backlash correcting methods have been proposed. However, since the backlash changes depending on the change of the tool post weight due to the change of the mounting tool and the processing conditions such as the feed speed, it is completely removed by the proposed method of removing or correcting a certain amount of backlash as in the conventional method. Difficult to do. For this reason, when processing a workpiece with strict accuracy, the actually processed workpiece is measured outside the machine to determine the amount of backlash, and this is input to the NC device as a correction value.

However, for example, a workpiece W shown in FIG. 3, the X-axis moving direction on the cutting side during creation processing by simultaneous two-axis control needs to reverse the X-axis passing through the spherical center a to the field. Alternatively, in the case of an arc surface, the backlash amount at the time of this reversal is difficult to be accurately obtained even by external measurement. For this reason, the present situation is that the processing is repeated while changing the correction value as needed, and the best amount of backlash correction is currently obtained.

[0004]

The method for obtaining the amount of backlash correction at the time of machining a spherical or arcuate surface as described in the prior art has a problem that it is inefficient and requires skill. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object thereof is to provide a highly efficient and unmanned sphere or arc surface processing capable of automatically obtaining and correcting an optimum backlash by in-machine measurement. It is an object of the present invention to provide an apparatus for measuring and correcting backlash at the time.

[0005]

A backlash correction apparatus for machining a spherical surface or an arc surface according to the present invention is a spherical surface created by simultaneous two-axis control by changing the moving direction of an axis on a cutting side in an NC lathe. Or a device that measures and corrects the backlash amount at the time of machining an arc surface, a sensor detachably provided on a tool post, and a spherical center or an arc of the spherical surface on which a workpiece gripped by a chuck is created. the two coordinate values when said sensor in axial movement as the cutting side is in contact with the two points equidistant accustomed to longitudinal axial comprising a feed side for a circle or <br/> arc center of the surface Means for storing a measurement program to be measured, calculating means for calculating the amount of backlash from the measured two coordinate values, and means for storing the obtained amount of backlash, the corresponding spherical or arc surface for the next and subsequent times. processing Is intended to correct the backlash with respect to the position command value becomes cut side axis.

[0006]

After the workpiece is gripped by the chuck and the sphere or the arc surface is created by the simultaneous two-axis control, the measuring program is used to continue the feed of the sphere or the arc center on the feed side with respect to the center of the sphere or the arc center. 2 when the sensor abuts on two points separated by a certain distance in the front and back by axial movement on the cutting side
The two coordinate values are detected, and the backlash amount is obtained from the difference between the two detected coordinate values and stored. Then, the backlash amount stored at the time of machining of a spherical surface or an arc surface after the next time is called to correct the position command value of the axis on the cutting side.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a chuck 3 is fitted concentrically on the tip of a spindle 2 rotatably supported on a headstock 1 of an NC lathe, and a workpiece W is gripped by the chuck 3. On the other hand, a tool rest 4 is provided on a bed (not shown) via a saddle (not shown) so that the tool rest 4 can be moved and positioned in the X-axis and Z-axis directions, and the tool rest 4 can be rotated and indexed about a turning center axis in the Z-axis direction. A turret 5 is provided.

A tool T and a touch sensor 6 are detachably attached to a plurality of tool attachment stations provided at equal intervals on the turret 5, respectively. The touch sensor 6 outputs a touch signal when it comes into contact with the workpiece W, and the same sensor used for in-machine measurement for setting the processing origin can be used. The block diagram part of FIG. 1 shows a backlash correction system according to the present invention in an NC device. Machining program storage unit 8
Is a part that stores the input machining program. The program analysis section 9 analyzes the program contents and sorts signals into necessary places.

A function generator 10 generates a function necessary for X / Z axis control. The X-axis motor drive control unit 11 controls the X-axis motor 1 so that the X-axis position and the feed speed approach the command value.
Part that drives 2. The X-axis rotation detector 13 detects the current X-axis position of the tool rest 4 from the rotation angle. The Z-axis motor drive control unit 14 drives the Z-axis motor 15 so that the Z-axis position and the feed speed approach the command values. The Z-axis rotation detector 16 is a part that detects the current Z-axis position of the tool rest 4 from the rotation angle.

The measurement program storage section 18 is a section for storing the input measurement program. The detection unit 19 is an X-axis or a Z-axis which is a cut side when a touch signal is
The part that detects the coordinate value of the current position of the axis. The backlash amount calculation unit 20 obtains a backlash amount from a difference between two coordinate values of the X axis or the Z axis from the detection unit 19. The backlash amount storage unit 21 is a part that stores the determined backlash amount.

Next, the operation of this embodiment will be described.
When the spherical machining of the workpiece W by the cutting tool T is completed according to the machining program, the turret 5 rotates and the touch sensor 6
Is indexed to the measurement position. Then, the X-axis and Z-axis movement of the tool rest 4 in accordance with the measurement program causes the touch sensor 6 to move away from the spherical center a of the workpiece W in the machining program by a distance L in the X-axis direction at a point away from the main axis side in the Z-axis direction. After the workpiece is positioned above the workpiece W, the touch sensor 6 comes into contact with the spherical surface of the workpiece W (indicated by a solid line in the drawing) as the tool rest 4 moves toward the workpiece W in the X-axis direction, and a touch signal is output. The X-axis coordinate value of the current position at this time is detected by the detection unit 19, and at the same time, the X-axis movement of the tool rest 4 stops.

The X-axis coordinate value is stored in the backlash amount calculation unit 20. Subsequently, the upper position of the work separated in the X-axis direction at a point where the touch sensor 6 is separated from the sphere a by the distance L toward the main axis side in the Z-axis direction. After that, the tool post 4 is moved toward the workpiece W in the X-axis direction in the same manner as described above, and the touch sensor 6 is moved.
Abuts on the spherical surface (indicated by a virtual line in the figure), the X-axis coordinate value of the current position at this time is detected by the detection unit 19, and is sent to the backlash amount calculation unit 20. A backlash amount in the X-axis direction is obtained from a difference between the Z-axis coordinate value stored first and the sent Z-axis coordinate value in the backlash amount calculation unit 20 and stored in the backlash amount storage unit 21. The correction is performed on the X-axis command value at the time of spherical surface forming processing by the subsequent processing program. In addition, if there is a backlash during the spherical surface forming process, the inversion operation is actually delayed even if the inversion is performed with the X-axis command value. Therefore, it is necessary to set the distance L in consideration of the delay.

When the workpiece has a plurality of spherical surfaces or circular arc surfaces in which the moving direction of the axis on the cutting side is reversed, each backlash amount is detected and stored in order to cope with each backlash amount depending on the processing conditions. In addition, the correction can be performed by sequentially calling the backlash amount corresponding to the processing location at the time of generating processing.

In the case of an arc surface of a work W1 for creating an arc surface by reversing operation in the Z axis direction as shown in FIG. 2, the tool post 4 is moved to the main axis side in the Z axis direction. The backlash amount is obtained by measuring the Z-axis coordinate values of two points on the arc surface which are separated from the arc center b of the workpiece W1 by an equal distance L to the plus side and the minus side in the X-axis direction with respect to the arc center b of the work W1, thereby obtaining the backlash amount. At times, the Z-axis position command value is corrected.

[0015]

Since the present invention is configured as described above, the following effects can be obtained. When the sensor comes into contact with two points at equal distances in the axial direction on the cutting feed side from the spherical center or arc center of the spherical surface or circular arc surface of the workpiece created in the machine, on the cutting side, and at the cutting side. The two coordinate values are measured, and the backlash amount is calculated from the difference between the two coordinate values, and the position command value of the axis on the cutting side during simultaneous spherical surface or arc surface creation processing by simultaneous two-axis control is corrected. This eliminates the need to repeat the actual processing while changing the correction value as needed as in the related art to obtain the optimum amount of backlash, thereby greatly reducing the working time.

Further, after the first product machining by the measurement program is completed, the measurement program automatically measures and corrects the backlash amount, so that unmanned high precision machining can be achieved. Further, most of recent NC devices have an in-machine measuring device for obtaining a machining origin. In this case, a part of a measuring mechanism of the device is used to make the device very inexpensive.

[Brief description of the drawings]

FIG. 1 is a diagram combining a diagram showing a main part and a work of a lathe according to an embodiment of the present invention, and a block diagram of a backlash measurement and correction system.

FIG. 2 is a view showing a work different from that of FIG. 1;

FIG. 3 is a diagram of a work for explanation of a conventional technique.

[Explanation of symbols]

 Reference Signs List 1 headstock 2 spindle 3 chuck 4 turret 5 turret 6 touch sensor 18 measurement program storage unit 19 detection unit 20 backlash amount calculation unit 21 backlash amount storage unit W work a spherical center

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G05B 19/404 B23Q 15/04

Claims (1)

(57) [Claims] 1. An apparatus for measuring and correcting a backlash amount at the time of machining a spherical surface or an arc surface created by simultaneous two-axis control by changing a moving direction of an axis on a cutting side in an NC lathe. The distance between the sensor provided detachably on the tool post and the center of the spherical surface of the spherical surface or the circular arc of the circular arc surface on which the workpiece gripped by the chuck is formed is equal in the axial direction on the feed side. Means for storing a measurement program for measuring two coordinate values when the sensor abuts on two points in the axial direction on the cutting side, and calculating means for obtaining a backlash amount from the measured two coordinate values; And means for storing the determined backlash amount.
A backlash measurement and correction device for spherical or circular surface machining, wherein the backlash amount is corrected for a position command value of an axis on the cutting side when a corresponding spherical or circular surface is machined next time.