JPH0531651A - Center height regulating device for machine tool - Google Patents

Abstract

PURPOSE:To perform automatic regulation of the height of a cutting edge according to the change in the rotational center of a main spindle, in a lathe wherein the main spindle is supported by a fluid bearing. CONSTITUTION:A disc body 4 rotating on the same axis as that of a main spindle is attached to a main spindle 2. An optical displacement gage 6 to measure the disc body 4 in a non-contact state is installed to a headstock. An attaching body 9 to which a bite 10 is attached is vertically resiliently displaceably supported to a tool rest 7 though a piezoelectric element 8. Based on an output from the optical displacement gage 6, a computing circuit 11 computes a displacement amount of the rotation center of the main spindle 2. A piezoelectric element drive circuit 12 applies a given voltage to a piezoelectric element 8 according to the computing result of the computing circuit 11 to control expansion and contraction of the piezoelectric element 8. This constitution causes automatic adjustment of the height of the cutting edge of the bite 10 to the, rotation center of the main spindle 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center height adjusting device for a machine tool having a spindle supported by a fluid bearing.

[0002]

2. Description of the Related Art Generally, a lathe having a main shaft supported by a fluid (air, oil) bearing is often used when processing a workpiece such as an optical lens or a mirror. The center of rotation easily changes with changes in cutting conditions. Factors of variation include load variations of the spindle due to changes in the weight of the chuck or the workpiece, dynamic pressure variations caused by changes in the spindle rotational speed, and cutting force variations due to the cutting tool. Since the shape accuracy of the work deteriorates when the center of rotation of the spindle changes, it is necessary to accurately adjust the core height according to the displacement of the spindle, especially when cutting a work that requires high accuracy up to the center. There is. Therefore, conventionally, as shown in FIG.
As shown in FIG. 5, the height of the cutting tool 22 is attached to the tool rest 21, and when the rotation center of the main shaft 23 changes, the screw 24 is turned to adjust the cutting edge height of the cutting tool 22 each time. ..

[0003]

However, according to this, it is necessary to reset the core height each time the cutting conditions change, which is not only a waste of considerable time but also wear of the cutting tool 22. There was a problem that the amount increased. Therefore, an object of the present invention is to provide a core height adjusting device for a machine tool capable of automatically adjusting the height of the cutting edge according to the change in the center of rotation of the spindle.

[0004]

In order to solve the above-mentioned problems, a core height adjusting device of the present invention is a disk body which rotates on the same axis as a main shaft supported by a fluid bearing, and the disk body. A non-contact type displacement meter to measure, a calculation means for calculating the displacement amount of the rotation center of the spindle based on the output of the displacement meter, a blade edge height adjustment mechanism provided on the tool rest, and a calculation result of the calculation means. And a control means for controlling the blade height adjusting mechanism.

[0005]

According to the core height adjusting device of the present invention, the displacement gauge measures the disk body in a non-contact state, and the computing means computes the displacement amount of the rotation center of the spindle based on the output of the displacement gauge. Then, the control means controls the blade tip height adjusting mechanism of the tool rest according to the calculation result of the computing means, whereby the blade tip height is automatically adjusted to the rotation center of the spindle.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a lathe will be described below with reference to the drawings. As shown in FIGS. 1 and 2, a spindle 2 is rotatably supported by a headstock 1 of a lathe via a fluid bearing (not shown), and a chuck that holds a work W on the same axis is provided on the spindle 2. 3 and a disc body 4 are attached. An optical displacement gauge 6 is fixed to an upper part of the headstock 1 via a bracket 5, and a lower end of the optical displacement meter 6 is arranged to face the outer peripheral surface of the disk body 4 in a non-contact state. A mounting body 9 is provided on the upper surface of the tool rest 7 via a piezoelectric element 8 as a blade edge height adjusting mechanism.
Is supported so that it can be elastically displaced up and down, and its mounting body 9
The height of the cutting edge of the cutting tool 10 attached to can be adjusted as the piezoelectric element 8 expands and contracts. In FIG. 1, 11
Is an arithmetic circuit, which constitutes arithmetic means for calculating the displacement amount of the rotation center of the spindle 2 based on the output of the optical displacement meter 6. Reference numeral 12 denotes a piezoelectric element drive circuit, which constitutes a control means for applying a voltage according to the calculation result of the calculation circuit 11 to the piezoelectric element 8 to control the expansion / contraction amount thereof.

With the above structure, the core height adjusting method of this embodiment will be described below with reference to the flowchart and waveform chart of FIG. First, the work W is test-cut in order to align the cutting edge of the cutting tool 10 with the rotation center of the spindle 2, and the reference waveform is detected based on the output of the optical displacement meter 6 at the completion of the test cutting (step S1). Then sin
The center line of the reference waveform generated functionally is obtained by the arithmetic circuit 11 using an arithmetic expression such as the least square method, and the reference center position of the spindle 2 is determined (step S2). Then, normal cutting is performed, the disk body 4 is measured by the optical displacement meter 6, and the waveform at the time of cutting is continuously detected based on the output (step S3). During the cutting, load fluctuation,
When the center of rotation of the spindle 2 changes due to factors such as dynamic pressure fluctuations and cutting force fluctuations, the output of the optical displacement meter 6 changes, and the center line of the detected waveform deviates from the reference center position. Then, the center line of the waveform at this time is obtained by the arithmetic circuit 11, and the difference between the calculated value and the reference center position, that is, the displacement amount Δδ of the rotation center of the spindle 2 is calculated (step S4). Then, the result of this calculation is sent to the piezoelectric element drive circuit 12, a required voltage is applied to the piezoelectric element 8, and as the piezoelectric element 8 expands and contracts, the cutting edge height of the cutting tool 10 is automatically set to the rotation center of the spindle 2. (Step S5). Therefore, according to the core height adjusting device of this embodiment, the cutting edge height of the cutting tool 10 is automatically adjusted according to the change of the rotation center of the spindle 2, so that when the cutting conditions are changed, unlike the conventional case. However, it is not necessary to reset the core height, the processing time can be significantly shortened, and the wear amount of the cutting tool 10 can be reduced.

The present invention is not limited to the above embodiment, and for example, the installation location of the optical displacement meter 6 can be changed appropriately, or the optical displacement meter 6 can be replaced by a magnetic displacement meter or an ultrasonic displacement meter. , Use a blade height adjustment mechanism composed of a pulse motor and a feed screw, or apply it to machine tools other than lathes such as milling machines or grinders.
The shapes and configurations of the respective parts can be arbitrarily modified and embodied without departing from the spirit of the present invention.

[0009]

As described in detail above, according to the present invention, the calculation means calculates the displacement amount of the rotation center of the main shaft based on the output of the displacement meter, and the control means adjusts the height of the cutting edge according to the calculation result. Since the adjusting mechanism is configured to be controlled, there is an excellent effect that the height of the cutting edge can be automatically adjusted according to the change of the rotation center of the main shaft supported by the fluid bearing.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a core height adjusting device in a lathe showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a headstock and a tool rest of the lathe shown in FIG.

FIG. 3 is a flowchart illustrating a method of adjusting a core height of the lathe shown in FIG.

FIG. 4 is a perspective view showing a conventional lathe.

[Explanation of symbols]

1-. Spindle head, 2 ... Spindle, 3 Chuck, 4 Disc body, 5 Bracket, 6 Optical displacement gauge, 7 Turret, 8 Piezoelectric element, 9 mounting Body, 10-bite, 11-arithmetic circuit, 12-piezoelectric element drive circuit, W
··work.

Claims (1)

Claim: What is claimed is: 1. A disk body rotating on the same axis as a main shaft supported by a fluid bearing, a non-contact type displacement meter for measuring the disk body, and an output of the displacement meter. Based on the calculation means for calculating the displacement amount of the rotation center of the main shaft, the cutting edge height adjusting mechanism provided on the tool rest, and the control means for controlling the cutting edge height adjusting mechanism according to the calculation result of the calculating means. A machine height adjusting device for machine tools.