JPS61152353A - Automatic centering device - Google Patents

Abstract

PURPOSE:To enable automatic centering by moving and controlling a workpiece pressing device, according to the displacement of an off-center detecting device in contact with the workpiece rotating with the turntable of the centering device where an optical disc, etc. are centered about the central part of the turntable. CONSTITUTION:A round workpiece W placed on a turntable 1 is rotated therewith and a slide block 3 is made to move in the radial direction of the turntable 1 by a motor 6 so that the bearing 12 of an off-center detecting device 10 will come in contact with the workpiece W, thereby causing the vibration of the said device 10 about a pin 9, depending upon the displacement of the workpiece W and the turntable 1. The extent of the vibration is detected by a displacement detecting device 14 and the motor 6 is actuated for advancing the slide block 3. Then, the contact point a is pressed by a spring 16 and the center O2 of the workpiece W is correctively made to shift toward the center O1 of the turntable 1. The positional detection and correction are so repeated for the proper centering of the workpiece W. By the foregoing constitution of mechanism, it becomes possible to ensure automatic centering of high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic centering device that aligns a disc such as an optical disc placed on a turntable with the center of rotation of the turntable.

[Conventional technology]

It is desirable that the guide track of an optical disk, the servo track of a magnetic disk, etc. be the same as the outer diameter of the disk. To satisfy this request.

When recording information, it is necessary to align the center of the outer diameter of the disk with the center of rotation of a turntable that supports the disk.

To center the turntable and disc (hereinafter referred to as a circular workpiece), a hole is formed in the center of the workpiece on the same axis as the outer diameter, and a circular protrusion is provided on the turntable side on the same axis as the center of rotation. There has been a conventional method of positioning a circular workpiece by fitting a hole into a hole.

However, in the case of a workpiece without a hole, the above mechanical positioning method cannot be adopted.

In this case, centering can be done by placing a circular workpiece on a turntable, rotating the turntable, measuring the center runout of the outer diameter of the circular workpiece, and then correcting the workpiece position with a hammer or the like. It is being

[Interval points to be solved by the invention] Manual centering as described above is accurate while directly measuring the outer diameter of the circular workpiece, but on the other hand,
This method requires advanced technology and skill, and is disadvantageous in that it requires a lot of effort and time.

Therefore, the technical object of the present invention is to eliminate the above-mentioned disadvantages, automate the centering work of circular workpieces, and enable highly accurate centering.

[Means to resolve the issue]

In order to solve the above-mentioned electrification problem, the present invention is provided with a drive device that moves a slide block in the radial direction of a turntable on which a circular workpiece can be placed, and the slide block is provided with a drive device that moves a slide block in the same direction as the slide block. A runout detector that is movably supported and returned to a set position by a spring, and a displacement detector that detects the amount of displacement of the runout detector.

A control device that controls the drive device based on the detection signal, and a workpiece presser fixed to the slide block are respectively provided, and the workpiece presser is returned to the workpiece pressing position and the center runout detector is returned to the set position. The detection positions of the turntable are arranged on the same circumference centered on the rotational axis of the turntable or in the vicinity thereof.

[Effect]

To center a circular workpiece placed on a turntable using the centering device configured as described above,
First, a circular workpiece is rotated in one direction with a turntable, a slide block is moved in the radial direction of the rotating circular workpiece, and a center runout detection body that moves due to pressure on the workpiece's outer circumference and the amount of displacement of the detection body are detected. At the same time, the workpiece pusher pushes the workpiece outer circumference toward the center of rotation of the turntable (the contact point between the workpiece pusher and the workpiece and the center of rotation of the turntable). The circular work is centered by the force acting on the line connecting the two, and the slide block is moved in the radial direction of the circular work until the detection signal output from the detector reaches the set amplitude value. When the output signal from the detector reaches a set amplitude value, the drive device is reversed by a signal from the control device to move the slide block in a direction away from the outer periphery of the circular workpiece.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, on the outside of the turntable 1,
A block support stand 2 is arranged, and the slide block 3 supported on the block support stand 2 is movable in the radial direction of the turntable 1.

A screw hole 4 is formed in the back of the slide block 3, and a screw rod 5 screwed into the screw hole 4 is connected to a rotating shaft 7 of a motor 6 supported on the block support base 2. When you drive.

The slide block 3 moves in the radial direction of the turntable 1.

Further, a pin 9 is provided at the front portion of the slide block 3, and one end of the center runout detector 10 is rotatably supported by the pin 9. A protruding shaft 11 is provided at the other end of this center runout detector 10, and a bearing 12 that can come into contact with the outer periphery of a circular workpiece W placed on the turntable 1 is provided at the tip of the protruding shaft 11. Rotatably supported.

The above-described center runout detector 10 is rotated rearward about the pin 9 due to center runout on the outer periphery of the circular workpiece W rotating together with the turntable 1, and is held at a set position by a spring 13 provided between it and the slide block 3. be returned. The elasticity of this spring 13 is extremely small, and has enough elasticity to not move the circular workpiece W.

Further, the amount of movement of the other end of the center runout detector 10 is detected by a displacement amount detector 14' supported by the slide block 3. Here, the displacement detector 14 is a non-contact type that utilizes eddy current loss.

The detection signal from the detector 14 is input to a control device 17, and the operation of the motor 6 is controlled by the output signal from the control device 17.

Note that the method of supporting the center runout detector 1o is not limited to the illustrated example, and may be supported so as to be movable in the same direction as the slide block 3.

Roughly speaking, a presser 15 for pressing a workpiece is provided at the front of the slide block 3, and a bearing 16 is rotatably supported at the tip of the presser 15. The position where this bearing 16 presses the workpiece W and the bearing 12 of the center runout detector 10 returned to the set position are the circular workpiece W.
The positions pushed by the outer periphery of the turntable 1 are arranged on the same circumference centered on the axis of the turntable 1 or in the vicinity thereof.

In the case of the embodiment, the workpiece contact position of the bearing 12 of the core runout detector 10 is located closer to the axis of the turntable 1 than the workpiece suppression position of the bearing 16 of the presser 15 .

Now, if the circular workpiece W is simply placed on the turntable 1, the center of the circular workpiece W and the rotation center of the turntable 1 may coincide with the heat output, but in most cases,
The center of the circular workpiece W is eccentric with respect to the rotation center of the turntable 1. In the eccentrically supported state, one of the two intersections where the straight line l connecting the rotation center O1 of the turntable 1 and the center 02 of the circular workpiece W intersects with the outer periphery of the circular workpiece W.

If one of the intersection points is a protruding point a, the protruding point a is at the farthest position from the center of the turntable 1, and when the turntable 1 is rotating, the protruding point a is
It moves in a circle with the distance to the center of (the distance O1a in FIG. 1) as the radius.

When the circular workpiece W placed on the turntable 1 is eccentric, when the turntable 1 is rotated and the motor 6 is driven to move the slide block 3 in the radial direction of the turntable 1, it becomes circular. The protruding point a of the workpiece W begins to come into contact with the bearing 12 of the runout detector 10 5, and due to this contact, the runout detector 1 moves around the pin 9.
Q rotates, and the displacement amount detector 14 detects the amount of movement of the other end of the center runout detector 1o. Further, since the protruding point a next comes into contact with the bearing 16 of the presser 15, the circular workpiece W is pushed by the bearing 16, and due to the pressure, the circular workpiece W is moved so that its center 02 is directed toward the center O1 of the turntable 1. Moving.

When the position of the circular workpiece W is corrected and the center 02 of the circular workpiece W matches the center 01 of the turntable 1, the center runout detector 10 repeats extremely small rotations, and the displacement detector at that time The detected amplitude signal from 14 switches the motor 6 to reverse rotation, and moves the slide block 3 in a direction away from the outer periphery of the circular workpiece W. This completes the centering work of the circular workpiece W.

The above-mentioned centering work is performed by detecting the rotation speed (rotation angle) of the turntable 1 with a rotary encoder, inputting the one rotation signal to the control device 17, and calculating it with the runout signal input from the sensor 14. Output the runout signal.

FIG. 2 shows a waveform output from the control device 17, and point A indicates the position where the protruding point 3 of the circular workpiece W starts to come into contact with the bearing 12 of the center runout detector 10.

In the embodiment, the feed speed change position voltage of the slide block 3 is set, and when the voltage output from the detector 14 reaches the change position voltage, the rotation speed of the motor 6 is lowered to feed the slide block 3 at a low speed. That's how it is.

Further, the center runout of the circular workpiece W is corrected and the motor 14 is rotated in reverse at the 0 point where the output voltage from the detector 14 becomes a runout below a set value.

Note that if a bandpass filter for the turntable rotation speed frequency is inserted into the output from the detector 14, it is possible to remove the adverse effects caused by the surface roughness of the outer periphery of the circular workpiece W, the roundness of the outer periphery, distortion, etc. Furthermore, it is possible to eliminate the influence of the DC component on the setting detection signal due to the difference in curvature caused by the difference in workpiece diameter.

〔effect〕

As described above, according to the present invention, the circular workpiece is automatically moved by rotating the turntable supporting the circular workpiece in one direction and moving the slide block in the radial direction of the turntable in this state. Along with being able to center.

Since centering work is performed while detecting center runout on the outer periphery of a circular workpiece, a single circular workpiece can be centered accurately and in a short time.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of a centering device according to the present invention, and FIG. 2 is a graph showing a voltage waveform output from a detector of the same device. 1... Turntable, 3... Slide block,
4...Threaded hole, 5...Threaded rod, 6...Motor, 1
0... Core runout detection body, 13... Spring, 14.
...Displacement amount detector, 15...Press element NCHN

Claims (1)

[Claims] It consists of a turntable on which a circular work can be placed, a slide block that is movable in the radial direction of the turntable, and a drive device that moves the slide block in the radial direction of the turntable, and the slide block includes:
It is supported so that it can move in the same direction as this slide block,
A runout detector that is returned to a set position by a spring, a displacement detector that detects the amount of displacement of the runout detector and controls the drive device based on the detection signal, and a displacement detector that is fixed to the slide block. A workpiece presser is provided, and the workpiece pressing position of the presser and the detection position of the runout detector returned to the set position are arranged on the same circumference centered on the rotation axis of the turntable or in the vicinity thereof. automatic centering device.