JPH05318287A - Super-precision working machine - Google Patents

Abstract

PURPOSE:To enhance the machining accuracy by measuring the actual shape of a work quickly and precisely by the on-machine system, and correcting the machining error by the in-process control on the basis of the data acquired from measurement. CONSTITUTION:A laser interferometer 9 not likely to be influenced by vibration and the straightness in movement of the guide surface is installed on the X-axis table 5 of a super-precision working lathe. The shape of the machining surface of a work 12 under machining is measured by this laser interferometer 9, and the acquired data is fed to an NC device 19 through a processor 16. The NC device 19 prepares the machining error correction data on the basis of this measuring data, to serve for controlling servo motors 7 and 10 which drive the spindle stock 6 and tool rest 8, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-precision processing machine which measures an actual shape of a work piece by an on-machine machine and corrects a processing error by in-process control.

[0002]

2. Description of the Related Art Generally, when a work is mirror-finished by using an ultra-precision processing machine such as a lathe, it is essential to measure the shape of the machined surface. Conventionally, an electric micrometer has been widely used as the shape measuring means.However, when this is installed on a processing machine, a large measurement error occurs due to the influence of vibration and movement straightness of the guide surface. The shape measurement on the machine was impossible. Therefore, conventionally, the work is detached from the chuck after the measurement, the machining error is fed back to the NC machining data, the work is reattached to the chuck, and the remachining is performed to correct the error.

[0003]

Therefore, according to the conventional ultra-precision processing machine, it is necessary to remove the work from the chuck for shape measurement, which not only deteriorates the work efficiency, but also causes the work due to the mounting error. There was a problem that the accuracy was also lowered. Therefore, an object of the present invention is to provide an ultra-precision machine capable of measuring the actual shape of a work piece on-machine quickly and accurately and correcting the machining error by in-process control based on the measured data to improve the machining accuracy. To do.

[0004]

In order to solve the above-mentioned problems, an ultra-precision processing machine according to the present invention is provided with a laser interferometer installed on the processing machine for measuring the shape of a work and the laser interference. And an NC control device that corrects the machining error of the workpiece based on the measurement data of the meter.

[0005]

According to the ultra-precision processing machine of the present invention, a laser interferometer is used which is not easily affected by vibration and movement straightness of the guide surface. The actual shape of can be measured on-machine quickly and accurately. Then, the measurement data of the laser interferometer is input to the NC control device, and here, correction data for correcting the machining error of the work is created. Therefore, the machining error can be automatically corrected by the in-process control, and the workpiece can be machined with high precision.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in an ultra-precision machining lathe will be described below with reference to the drawings. As shown in FIG. 1, a bed 3 is installed on a base 1 of an ultraprecision lathe via a vibration isolation table 2, and a Z-axis table 4 and an X-axis table 5 can slide on the bed 3, respectively. Supported by. A headstock 6 containing a built-in motor is installed on the Z-axis table 4 and is sent in the Z-axis direction by a servomotor 7. A tool rest 8 and a laser interferometer 9 are installed on the X-axis table 5, and these are fed integrally by a servomotor 10 in the X-axis direction. Then, the work piece 12 is held by the chuck 11 on the headstock 6, the tool 13 is attached to the tool rest 8, and the position detectors 14 and 15 are provided on the servomotors 7 and 10, respectively.

The laser interferometer 9 is equipped with a CCD camera for picking up an image of the end face of the work 12 by laser light (parallel lines).
The measurement data obtained by imaging is output to the processor 16 as an analog signal. The processor 16 is provided with an A / D converter 17 for digitizing the measurement data, and a three-dimensional data processing circuit 18 for producing three-dimensional data representing the uneven shape of the processed surface. The processor 16 is an NC controller 19
CRT image processing for performing data processing for displaying the interference fringe pattern (see FIG. 4) and the three-dimensional shape (see FIG. 5) of the processed surface on the CRT display 20 based on the output of the processor 16. A circuit 21 and an X-feed / Z-feed correction circuit 22 for creating X-axis and Z-axis shape error correction data based on the measurement data of the laser interferometer 9 and the NC processing data are provided. Then, the NC control device 19 is configured to output a shape error correction signal to the position detectors 14 and 15 to control the servomotors 7 and 10.

A method of correcting the shape error of the work 12 by using the laser interferometer 9 in the ultra-precision machining lathe constructed as described above will now be described with reference to the flowchart shown in FIG. First, as the headstock 6 moves in the Z-axis direction and the tool rest 8 moves in the X-axis direction, the end face of the work 12 is cut by the tool 13 (step S1), and then the end face shape of the work 12 is cut by the laser interferometer 9. Is measured (step S2). In this case, since the laser interferometer 9 which is hardly affected by vibration and movement straightness of the guide surface is used, this can be installed on the X-axis table 5 of the processing machine, and the work piece 12 can be held by the chuck 11 while being held. In this state, the actual shape can be measured quickly and accurately by the on-machine measurement method. Next, the measurement data of the laser interferometer 9 is subjected to three-dimensional shape processing by the processor 16 to create three-dimensional data representing the uneven shape of the processed surface (step S).
3). Then, in the NC controller 19, the laser interferometer 9
Positioning data in the Z-axis direction for correcting the machining error of the work 12 is created based on the measurement data of (1) by the procedure described later (step S4).

Thereafter, the maximum value δzmax of the processing error is compared with the allowable value δza (step S5). When the machining error maximum value δzmax is larger than the allowable value δza, the Z-axis positioning data in the NC data is corrected (step S6), and the work 12 is recut. Then, the above steps are repeatedly executed until the maximum processing error δzmax becomes equal to or less than the allowable value δza. When the maximum processing error δzmzx becomes equal to or less than the allowable value δza, the measured value and the evaluation at this time are output (step S7). Here, the interference fringe pattern and the three-dimensional shape of the processed surface are displayed as the measured values, and, for example, “GOOD” is displayed as the evaluation on the CRT display 20 of the NC control device 19. Therefore, the machining error can be automatically corrected by the in-process control, and the workpiece 12 can be machined with high precision. A printer for printing the measured value may be provided in the NC control device 19.

A procedure for creating the processing error correction data will be described with reference to the flowchart shown in FIG. The correction reference point is set at the center of the work 12. Therefore, prior to the cutting process, first, the diameter D of the work 12 is measured by a micrometer or the like and input to the NC control device 19 (step S11), and then the correction start coordinate value χn.
(Χn = D / 2) is calculated (step S12). When the work 12 is cut, the data line D is next searched from the measurement data of the laser interferometer 9, and FIG.
As shown in, the cross-sectional shape data passing through the center of the work 12 is collected (step S13). In FIG. 6, δ0
~ Δ3: processing error at the center of the work and each point passing therethrough,
δzmax: maximum machining error, D: workpiece diameter, δi
(Χi): correction data, n: number of divisions of the radius of the work. Note that n is the NC positioning resolution (for example, 0.1 μ
m), NC positioning resolution ≦ D / 2n, and the maximum value of n is nmax ≦ D / [2 × (NC positioning resolution)].

Subsequently, the measurement data is initialized, and the processing error value δz (χn) at the correction start point χn is set to 0 (step S14). After that, the correction data at each position in the X-axis direction is δi (χi) = δz (χi) −δ
It is calculated by z (χn) (step S15), and a correction table that associates the position with the correction value is created according to the calculation result (step S16). Then, this correction data is fed back to the NC servo (step S17), whereby the servo motor 7 of the headstock 6 is controlled.

Although the end surface processing of the work 12 has been described in the above embodiment, the present invention can be applied to the peripheral surface processing of the work 12. In this case, the peripheral surface shape of the laser interferometer 9 is measured. The servo motor 10 of the tool rest 8 is controlled based on the data. Further, the present invention is not limited to only a lathe, and may be applied to various ultra-precision processing machines such as a grinder or a lapping machine.
The configuration of each part can be appropriately changed and embodied within a range not departing from the spirit of the present invention, such as changing the installation location of the laser interferometer 9 to an arbitrary position on the processing machine.

[0013]

As described above in detail, according to the present invention, the NC control device causes the machining error of the workpiece based on the measurement data of the laser interferometer which is less likely to be affected by the vibration and the movement straightness of the guide surface. Since it is configured to create the correction data, the laser interferometer can be installed on the processing machine to measure the actual shape of the workpiece on-machine quickly and accurately.
This has an excellent effect that the machining error is automatically corrected by the in-process control and the workpiece can be machined with high precision.

[Brief description of drawings]

FIG. 1 is a perspective view of an ultra-precision machining lathe showing an embodiment of the present invention.

2 is a flowchart showing a method of correcting a shape error of a work by using a laser interferometer in the ultra-precision machining lathe shown in FIG.

FIG. 3 is a flowchart showing a procedure for creating processing error correction data in the error correction method of FIG.

FIG. 4 is a front view of a CRT display showing an interference fringe pattern on a work surface.

FIG. 5 is a front view of a CRT display showing a three-dimensional shape of a work surface.

FIG. 6 is a schematic view showing a cross-sectional shape passing through the center of a work.

[Explanation of symbols]

1 ... Base, 2 ... Vibration isolation table, 3 ... Bed, 4 ... Z
Axis table, 5 ... X-axis table, 6 ... spindle headstock, 7,
10 ... Servo motor, 8 ... Turret, 9 ... Laser interferometer, 11 ... Chuck, 12 ... Work, 13 ... Tool, 14, 15 ... Position detector, 16 ... Processor,
19 ... NC control device, 20 ... CRT display.

Claims (1)

[Claims] 1. A laser interferometer installed on a processing machine for measuring a shape of a work, and an NC controller for correcting a working error of the work based on measurement data of the laser interferometer. Characteristic ultra-precision processing machine.