JPH07243497A - Friction drive device - Google Patents

Abstract

PURPOSE:To provide a high-precise friction drive device by using vertical movement influenced by an own weight by a method wherein at least three rotary vehicles to drive two straight advancing parts are provided and the role of a counterbalance is performed by one of the two straight advancing parts. CONSTITUTION:In a friction drive device using vertical movement influenced by an own weight, for example, friction bars 13 and 14 are arranged as two straight advancing parts and at least three rotary vehicles 9-11 are provided to drive the friction bars 13 and 14. The role of a counterbalance is performed by one of the friction bars 13 and 14. Namely, when an optical element is ground by using a head 20 for grinding arranged on a first slide bearing 5a on the first friction bar 13 side, a second slide bearing 16a on the second friction bar 14 side and a head 21 for measurement arranged thereon are operated as a counterbalance for canceling an own weight. This constitution eliminates the influence of the own weight and performs high-precise friction drive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction drive device which is used for vertical movements under the influence of its own weight and has extremely high precision.

[0002]

2. Description of the Related Art When an object is used while being moved straight, its smoothness is required, and when accuracy such as reproducibility with respect to position is required, a straight driving system for driving a straight moving portion is important. In recent years, a friction drive method without backlash has come into practical use rather than a method using a ball screw or the like.
However, when the rectilinear section is driven in the vertical direction due to gravity, the magnitude of the moving force changes depending on whether the rectilinear section is driven upward or downward, and the driving force changes. Further, it is difficult to stop at an appropriate position in the vertical direction. Therefore, when it is used while being driven up and down, or when it is stopped at a certain position, it is used in a so-called counter balance in which an object having the same mass as the linearly moving portion to be driven is balanced in the vertical direction.

Conventionally, as a counterbalance of this type, as shown in FIGS. 2 and 3, a weight 8 having the same mass as that of a straight-moving portion which is vertically driven is fixed to a wire 7 at a part of the straight-moving portion, and a first pulley is provided. It is known that the wire 7 is attached to the tip of the wire 7 through the 6a and the second pulley 6b to balance the wire. That is, the rectilinear section 2 is installed on the base 1, the supporting section 3 is provided on the rectilinear section 2, and the friction bar 4 is pressed from the supporting section 3 by both the first rotating wheel 5a and the second rotating wheel 5b. The weight 7 of the weight of the supported and supported straight moving part 2 and the mass of the object installed on the straight moving part 2 is attached to the weight 7 through the first pulley 6a and the second pulley 6b. It is configured.

[0004]

In the prior art as described above, in the case where the straight-moving portion is driven by the friction drive system in which vertical movement is affected by gravity and which enables extremely precise positioning without backlash. To remove the effect of own weight, attach a weight for its own weight from the straight section through a pulley with a wire to balance the vertical direction. At this time, although the influence of its own weight is almost eliminated, the attached weight shakes and vibrates the wire with the movement of moving the rectilinear portion by frictional driving, which deteriorates the vertical movement. Further, when the driving is stopped after the driving, a slight positional error occurs in the vertical direction with respect to the stopped position. Therefore, there is a problem in that the performance of the friction drive method, which is characterized by extremely accurate positioning without backlash, cannot be fully exhibited.

[0005]

[Means for Solving the Problems] In order to solve the above problems, as a result of earnest research, a friction drive device used for a vertical movement affected by its own weight is provided with two rectilinear portions, A friction drive device comprising: at least three rotating wheels for driving two rectilinear sections, wherein when driving the rectilinear sections, one of the rectilinear sections serves as a counter balance. Provided.

[0006]

According to the present invention, at least two rectilinear portions that move in the vertical direction are provided, and each of the rectilinear portions is provided with a support portion. At least three friction wheels are provided from the support portions. The device is configured by alternately sandwiching. At this time, when processing or measuring is performed by making the mass of each rectilinear section and the mass of an object installed on each rectilinear section equal, one serves as a counter balance. Therefore,
Since the device configuration is symmetrical and the counter balance itself is driven in the vertical direction by friction drive, there is no need to attach weights using wires. Therefore, there is no inconvenience of causing an error in the vertical movement due to vibration or the like. Therefore, it is possible to provide a friction drive device that is smoothly driven in the vertical direction and has no position error.

In the following, referring to the drawings, according to an example in which two sliding bearings are used for the straight-ahead portion, one of them is used for machining, and the other is used for measurement. The present invention will be described more specifically, but the present invention is not limited thereto.

[0008]

FIG. 1 is an external perspective view of the friction drive device used for processing and measurement. In FIG. 1, the first
The slide bearing guide 15b, the second slide bearing guide 16b, the first rotating wheel 9, the second rotating wheel 10, and the third rotating wheel 11 are bases 17.
It is installed on top. The first friction bar 13 taken out from the first support portion 18 on the first slide bearing 15a installed in the first slide bearing guide 15b so as to move back and forth is sandwiched between the first rotating wheel 9 and the second rotating wheel 10. At the same time, the second friction bar 14 taken out from the second support portion 19 on the second slide bearing 16a installed in the second slide bearing guide 16b so as to move back and forth is sandwiched between the second rotating wheel 10 and the third rotating wheel 11. . The press contact bar 12 presses all of the first rotary wheel 9, the second rotary wheel 10, and the third rotary wheel 11 with the first friction bar 13 and the second friction bar 14, so that the first rotary wheel 9, the third rotary wheel It is supported on the rotating wheel 11 and tightens the whole.

A processing head (a grinding head in this embodiment) 20 is installed on the first plain bearing 15a.
The first rotary wheel 9 has a DC servo motor as a rotary drive system and a DC tacho-generator for speed control (not shown). By this operation, the first plain bearing 15
a and the second plain bearing 16a are downward when the first rotary wheel 9 with a built-in motor rotates clockwise along the first and second plain bearing guide portions 15b and 16b, respectively.
The second plain bearing 16a can be moved upward. Similarly, when the first rotary wheel 9 rotates counterclockwise, the first plain bearing 15a moves upward and the second plain bearing 16a moves downward.

First sliding bearing 15a and second sliding bearing 16a
Are used at different heights in the vertical direction. When, for example, an optical element is ground by using the vertical movement of the grinding head 20 on the first plain bearing 15a, the second plain bearing 16a and the measuring head 21 on the second plain bearing 16a are counters for canceling their own weight. Act as a balance. After the grinding, the shape of the surface of the ground optical element can be measured by using the vertical movement of the measuring head 21 on the second plain bearing 16a, and the first plain bearing 15a can be measured. And the grinding head 20 on the first plain bearing 15a
Operates as a counter balance as described above.

In the case of this embodiment, the structure of the device is symmetrical with respect to the center of rotation of the second rotating wheel 10. Moreover, when one is used as a device, the other is a counter balance having a sliding bearing that moves up and down by friction drive. On the contrary, the counter-balanced type can be used as the device. Therefore, it can be used for precision processing and precision measurement to form and measure a surface with extremely high precision.

[0012]

As described above, according to the friction drive device of the present invention, the performance of the friction drive system with high smoothness and reproducibility of the position can be sufficiently exhibited, and the wire is used as the counter balance system. As in the case of using, there is no fear of error due to vibration, and stable vertical movement can be used from low speed to high speed. Moreover,
Machining the straight section itself used as counter balance,
Since it is used for measurement, an efficient friction drive device can be provided.

[Brief description of drawings]

FIG. 1 is an external perspective view of a friction drive device according to the present invention.

FIG. 2 is a front view showing counterbalance by a friction drive device and a wire according to a conventional technique.

FIG. 3 is an external perspective view of FIG.

[Explanation of symbols]

 1 base 2 rectilinear section 3 support section 4 friction bar 5a first rotary wheel 5b second rotary wheel 6a first pulley 6b second pulley 7 wire 8 weight 9 first rotary wheel 10 second rotary wheel 11 third rotary wheel 12 pressure contact Bar 13 1st friction bar 14 2nd friction bar 15a 1st sliding bearing 15b 1st sliding bearing guide 16a 2nd sliding bearing 16b 2nd sliding bearing guide 17 base 18 1st support part 19 2nd support part 20 grinding head 21 measurement More than head

Claims (1)

[Claims] 1. A friction drive device used for a vertical movement affected by its own weight, comprising two straight-moving portions, and at least three rotating wheels for driving the two straight-moving portions. A friction drive device characterized in that, when driving a straight-moving portion, one of the straight-moving portions serves as a counter balance.