JPH0699332A - Table device - Google Patents

Abstract

PURPOSE:To speed up positioning without increasing torque required for driving a feed screw in the table device employing the feed screw. CONSTITUTION:A sliding unit 4 is provided for the shaft end section of a feed screw 1 in such a way as to be slidably rotated with respect to the feed screw 1, and the sliding unit 4 is connected to a viscosity attenuation element 5 provided for a fixed section 3. The viscosity attenuation element 5 retains rotational vibration when the feed screw 1 is positioned. When excessive torque beyond requirement is applied to the viscosity attenuation element 5, the sliding unit 4 is slidably rotated with respect to the feed screw.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a table device, and more particularly to a table device capable of effectively damping vibrations during positioning.

[0002]

2. Description of the Related Art The following two types of attenuators have heretofore been used as means for damping the vibration of a table device driven by a feed screw.

(1) Rotating type attenuator An attenuator provided on the feed screw to suppress rotational vibration of the feed screw. This kind of attenuator is widely used as an attenuator when driving a feed screw using a stepping motor, for example.

(2) Direct-acting attenuator An attenuator in which a table is provided with an attenuator to suppress table vibration. This type of technology is disclosed in, for example, Japanese Patent Laid-Open No. 61-63028.

[0005]

In the above rotary attenuator, since it is necessary to add an auxiliary mass to the feed screw, rotational vibration can be effectively suppressed, but the equivalent mass increases. Therefore, there is a problem that the torque required to drive the feed screw increases.

On the other hand, if a direct-acting attenuator is used, an increase in equivalent mass can be avoided, but in general, in a table device driven by a feed screw, the equivalent mass of the feed screw (equivalent to the moment of inertia of the feed screw is equivalent). Since the value converted into the table mass) is close to the mass of the table itself, there were many cases where it was not enough to just suppress the table with a direct-acting attenuator.

An object of the present invention is to provide a table device which can suppress rotational vibration of a feed screw and can perform high-speed positioning without causing an increase in equivalent mass.

[0008]

Therefore, in the table device of the present invention, the slide device and the viscous damping element are provided in series between the feed screw and the fixing portion.

[0009]

The viscous damping element suppresses rotational vibration when positioning the feed screw. The braking torque required for damping at the time of positioning is small, and when a torque equal to or greater than this braking torque is applied to the viscous damping element, the sliding device rotates in a sliding manner. In this configuration, since no auxiliary mass is added, the rotational vibration of the feed screw can be suppressed without increasing the equivalent mass. Also, during operations other than table positioning, for example,
When it is necessary to rotate the feed screw at a high speed during long-distance movement, the sliding device slides and rotates. Therefore, the torque required to drive the feed screw does not increase beyond the slight braking torque required for damping during positioning.

[0010]

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

FIG. 1 shows an embodiment of the table device of the present invention. In the figure, the feed screw 1 is rotatably supported by a bearing 2 with respect to a fixed portion 3. The feed screw 1 and the fixing portion 3 are both illustrated with a part omitted, and the female screw threaded to the feed screw 1 and the table attached with the female screw and driven by the feed screw are also omitted. . A slide device 4 is provided at the shaft end of the feed screw 1 so as to be slidably rotatable with respect to the feed screw 1. The slider 4 is connected to a viscous damping element 5 provided on the fixed portion 3.

FIG. 2 shows an embodiment of the slider 4. The slide device 4 is pressed against the flange portion 101 provided on the feed screw 1 by the nut 401, the spring 402, and the pressing ring 403 at the shaft end of the feed screw 1. Flange part 1
Sliding members 404 are provided between 01 and the sliding device 4 and between the pressing ring 403 and the sliding device 4, respectively. With this configuration, the sliding torque of the slide device 4 that is slidably rotatable with respect to the feed screw 1 can be set arbitrarily. Further, by setting the spring constant of the spring 402 to be small, it is possible to suppress the fluctuation of the sliding torque of the sliding device 4 when the sliding member 404 is worn down.
The spring 402 is preferably a disc spring, a wave washer, a coil spring, or the like, and the sliding member 404 is preferably a low-wear material containing fluorine resin, molybdenum disulfide, or the like.

A sufficient effect can be obtained if the sliding torque of the sliding device 4 is set to be equal to or less than the friction of the bearing 2 supporting the feed screw 1. FIG. 3 is an example of a Bode diagram showing the characteristics of the table device mechanism system of the present invention, showing the effect when the sliding torque of the sliding device 4 is set to be approximately the same as the friction torque of the bearing 2. Is. In the figure, the gain is a value obtained by dividing the table displacement when the screw shaft 1 is vibrated with an amplitude that causes a problem during table positioning, by the table driving force. The characteristic curve A is the frequency response in the state where no damping element is added to the table, and a sharp resonance point is recognized. Characteristic curve B is the frequency response in the state where the direct-acting attenuator is designed to suppress only the table. The damping coefficient of the direct-acting attenuator is set in a range where harmful phase delay does not occur. Although the gain is reduced, a clear resonance point is still recognized, which shows that the system is difficult to control.

On the other hand, the characteristic curve C represents the frequency response in the state where the slide device 4 and the viscous damping element 5 are added to the feed screw 1 in addition to the direct acting type attenuator. The damping coefficients of the direct-acting type attenuator and the viscous damping element 5 are set in a range where harmful phase delay does not occur. No clear resonance point is observed, indicating that the system is easy to control. As described above, the sliding device 4
Since the sliding torque of is about the same as the friction torque of the bearing 2, the addition of the viscous damping element 5 slightly increases the driving torque of the feed screw 1, but sufficient damping is obtained at the time of table positioning. I understand.

FIG. 4 shows an embodiment of the viscous damping element 5. In the gap 501 formed by the groove portion of the viscous damping element 5 and the lever 405 provided on the slide device 4, the hydraulic oil 5
02 is satisfied. As a result, a damping force is applied to the slider 4 that is slidably rotatable with respect to the feed screw 1 by the squeeze effect of the oil film in the gap 501. Silicon oil, for example, may be used as the hydraulic oil. Further, the same effect can be obtained by using the viscous shearing force of the oil film, the electromagnetic force, or the like for the viscous damping element 5.

FIG. 5 shows a second embodiment of the viscous damping element 5. In this embodiment, the lever 405 is provided with a protrusion 406, and the lever 405 and the viscous damping element 5 are connected by a spring 407. According to this configuration, the change in the gap 501 can be suppressed to be small, and the characteristic change of the viscous damping element 5 can be suppressed.

[0017]

According to the present invention, the rotational vibration of the feed screw can be suppressed without substantially increasing the torque required to drive the feed screw. Therefore, the positioning speed of the table device using the feed screw can be increased. If this table device is applied to, for example, a semiconductor manufacturing device, the throughput can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an embodiment of a sliding device used in the present invention.

FIG. 3 is a characteristic diagram showing an example of characteristics of the table device mechanism system of the present invention.

FIG. 4 is a sectional view showing an embodiment of a viscous damping element used in the present invention.

FIG. 5 is a sectional view showing a second embodiment of the viscous damping element used in the present invention.

[Explanation of symbols]

1 ... Feed screw, 2 ... Bearing, 3 ... Fixing part, 4 ... Sliding device, 5
… Viscous damping element.

Claims (1)

[Claims] 1. A table device driven on a fixed portion by a feed screw provided on the fixed portion, wherein a slide device is provided so as to be slidably rotatable with respect to the feed screw. A table device characterized in that a viscous damping element is provided between fixing parts.