JPH02160441A - Table device - Google Patents

Abstract

PURPOSE:To move at a high speed by reducing friction coefficient at a table moving time, to stop in short time and to prevent vibration by increasing the friction force at its stopping time, by giving an adequate slide friction releasably by an electricity-machine converting means to a table guide member. CONSTITUTION:At the table 11 moving time no voltage is impressed on piezoelectric elements 23a, 25a, gaps 27, 29 are formed between the sliding members 23b, 25b of slide friction adding mechanisms 23, 25 and the sliding faces 7a, 9a of support members 7, 9 and a table 11 is moved at high speed on rails 3, 5 by the rotation of a feeding screw with the driving of a servomotor. When the servomotor driving is suspended, voltage is impressed on the piezoelectric elements 23a, 25a the sliding members 23b, 25b are abutted to the sliding faces 7a, 9a, the friction coefficient with the support members 7, 9 of the table 11 is increased and the table 11 is stopped in short time at the necessary position. Also the table 11 is strongly held at the working time and the vibration is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a table device for moving a workpiece to a desired position in a machine tool, and more particularly to a support structure for a table relative to a support stand.

[Prior Art] Conventionally, in the above-described table device, the table is movably supported on a rail fixed to a support base, and the table is moved to a desired position by rotation of a feed screw meshed with the table. configured to be moved.

The support structure for the table with respect to the rail includes a so-called sliding support structure in which the table is movably supported by bringing the support surface of the table into surface contact with the guide surface of the rail, and a support structure between the guide surface of the rail and the support surface of the table. There is a so-called rolling support structure that movably supports the table via balls or needles between the rails and the support surface of the table. Hydrostatic support structures that provide movable support in contact are generally known.

[Problems to be Solved by the Invention] However, among the above-mentioned support structures, in the sliding support structure, the rail and table are supported in surface contact, and the coefficient of friction between them increases, causing the table to Although it is possible to stop and hold the workpiece in a short time, there is a problem that the table is thermally deformed due to the heat generated by the friction, resulting in poor machining accuracy of the workpiece. In the sliding support structure described above, a spacer (gib) is inserted into the gap formed between the guide surface of the rail and the support surface of the table to prevent the table from wobbling. Adjusting the thickness was difficult and required skill. In other words, if the spacer is insufficiently thick, it will not be possible to prevent the table from rattling, resulting in poor positioning accuracy, while if the spacer is too thick, the resistance between the rail and the table will increase, causing the table to move at high speed. This poses a problem in that it becomes difficult to move the table, and a heavy load is placed on the drive system of the table, making movement control difficult.

In addition, in the above-mentioned rolling support structure, the rail and table are supported at a point or in a line, so the friction coefficient between them is reduced and the table can be moved at high speed, but it is possible to move the table at high speed until the table completely stops. The problem is that it takes time. Furthermore, in the static pressure support structure described above, since the table is supported without contacting the rail, the coefficient of friction between the two can be significantly reduced and the table can be moved at high speed. There is a problem that the table vibrates and machining accuracy deteriorates.

[Object of the Invention] In view of the above-mentioned conventional drawbacks, the object of the present invention is to reduce the coefficient of friction when moving the table to enable high-speed movement, and increase the frictional force when stopping the table to stop the table in a short time. An object of the present invention is to provide a table device that can prevent vibrations and improve machining accuracy.

[Means for Solving the Problems] Therefore, the present invention provides a table that is movably supported by a rolling support structure or a static pressure support structure on a guide member provided on a support base, and a table that is movably supported on a guide member provided on a support base, and a table that is movably supported by a rolling support structure or a static pressure support structure. In the table apparatus, a sliding friction adding mechanism is provided between the support base and the table to releasably apply appropriate sliding friction by electro-mechanical conversion means. This constitutes a table device.

[Operation] Since the present invention is configured as described above, when the table stops at a desired position, the sliding friction adding mechanism is activated by the electro-mechanical conversion means, and appropriate sliding occurs between the support base and the table. Friction is applied.

This increases the coefficient of friction between the table and the support base, allowing the table to stop at a desired position in a short time and preventing vibration of the table when processing a workpiece placed on the table. Accuracy can be increased. Furthermore, when the table is moved, the sliding friction of the sliding friction adding mechanism by the electro-mechanical conversion means is released, thereby lowering the coefficient of friction between the table and the support base.
The table can be moved at high speed.

[Example] Hereinafter, the present invention will be explained according to an example in which the present invention is implemented in a table device that moves a table one-dimensionally in a required direction.

FIG. 1 is a perspective view schematically showing the table device, and FIG. 2 is a partially omitted plan view showing the mounting state of the sliding friction adding mechanism. Rails 3 and 5 are fixed in parallel with a required spacing. Furthermore, two support members 7 and 9 having lengths that are approximately the same as the rails 3 and 5 are mounted on the support base 2 at a required distance from the rails 3 and 5.
is fixed parallel to the The support members 7, 9 have sliding surfaces 7a, 9a on opposite sides thereof.

A table 11 is supported on the rails 3, 5 so as to be movable in the longitudinal direction of the rails 3.5 via bearing members 13.15 such as ball bearings or needle bearings. A feed screw 17 having an axis in the longitudinal direction of the rails 3 and 5 is engaged with the table 11, and a DC servo motor 19 fixed to the support base 2 is connected to the shaft end of the feed screw 17. . The table 11 is reciprocated on the rails 3 and 5 by the feed screw 17 which rotates as the DC servo motor 19 is driven.

A mounting portion 21 is integrally formed on the lower surface of the table 11. The mounting portion 21 is attached to the sliding surface 7 of the support member 7°9.
Side surfaces 21a, 2 facing a, 9a with a predetermined interval
1b is formed. Two sliding friction adding mechanisms 23 and 25 are mounted on both sides of each side surface 21a and 21b, respectively, with a minute gap 27 and 29 of about 20 to 30 μm provided to the support member 7°9. . The minute gaps 27 and 29 are set below the amount of elongation of the piezoelectric elements 23a and 25a. These sliding friction adding mechanisms 23 and 25 are attached to piezoelectric elements 23a and 25a made of piezoelectric ceramics or the like having a piezoelectric phenomenon that extends in the direction of an electric field when a voltage is applied, and are attached to the tips of the piezoelectric elements 23a and 25a to support the above-mentioned support. A sliding contact member 23 having a high friction coefficient that contacts the members 7 and 9
b, 25b.

Next, the operation of the table device configured as described above will be explained with reference to FIGS. 2 and 3.

First, to explain the movement of the table 11, as shown in FIG. 2, when the table 11 is moved, the piezoelectric elements 23a, 25a
No voltage is applied to the piezoelectric elements 23a, 25a.
is reduced to its original shape.

At this time, the sliding member 23 of the sliding friction adding mechanism 23.25
b, 25b and the sliding surface 7a of the support members 7, 9.

A minute gap 27, 29 is formed between it and 9a.

When one DC servo motor is driven by the number of steps corresponding to the moving distance of the table 11 in the above state, the table 1
1 is moved in a desired direction on the rails 3 and 5 as the feed screw 17 rotates.

At this time, since the table 11 is supported by the rails 3 and 5 via the bearing members 13.15, the coefficient of friction between the two is reduced, and the table 11 is moved at high speed in the desired direction.

Next, to explain the effect when stopping the table 11,
In FIG. 3 showing the contact state of the sliding friction adding mechanism 23.25 with the sliding surfaces 7a, 9a of the support members 7, 9, the table 11 moves to a required position with the above-mentioned movement operation, and the DC servo When the drive of the motor 19 is interrupted, the piezoelectric element 23a.

A voltage of a predetermined value is applied to 25a. As a result, the piezoelectric elements 23a and 25a extend in the direction of the applied electric field.
b is brought into contact with the sliding surfaces 7a and 9a of the support members 7 and 9.

As a result, the coefficient of friction between the table 11 and the support members 7 and 9 increases, and the table 11 is stopped and held at a desired position in a short period of time. Furthermore, since the table 11 is firmly held while cutting the workpiece, vibration of the table 11 can be prevented.

In this way, in this embodiment, when the table 11 is moved, the table 11 is supported with respect to the rail 3.5 via the bearing member 13.15, and the support member is supported when no voltage is applied to the piezoelectric elements 23a, 25a. 7, 9 and sliding contact member 2
3b and 25b, the coefficient of friction between them becomes low, and the table 11 can be moved at high speed. Furthermore, when the table 11 stops at a desired position, the sliding contact members 23b, 25
b is the sliding surface 7a of the support members 7 and 9.

By bringing it into contact with 9a, the coefficient of friction between the two increases, making it possible to stop the table 11 in a short time, and also preventing vibration of the table 11 during workpiece machining, thereby increasing machining accuracy. .

In the above description, the table 11 is moved one-dimensionally in the desired direction along the rails 3.5 fixed on the support base 2. It may also be supported movably in a direction orthogonal to the longitudinal direction of 5 and moved two-dimensionally. That is,
a second rail and a second support member on the table 11;
The rails 3 and 5 fixed on the support base 2 and the support member 7°9 are fixed in a direction perpendicular to the longitudinal direction, and a second table is movably supported with respect to the second rail via a bearing. A second sliding friction adding mechanism that can come into contact with the second support member when voltage is applied is attached to the attachment part of the second table, and a second DC servo motor fixed to the table 11 is attached to the second table 11. A table device is constructed by meshing the connected second feed screw with the second table.

Furthermore, the above explanation assumes that when the table 11 is stopped, a voltage of a predetermined value is applied to the piezoelectric elements 23a, 25a, and the table 11 is stopped and held against the support member 7.9 with a predetermined coefficient of friction. However, the piezoelectric elements 23a, 2
The coefficient of friction with respect to the support member 7.9 may be made variable by controlling the voltage applied to the support member 5a.

Further, in the above description, the support members 7 and 9 are provided independently on the support stand 2, but a structure in which a part of the rail 3.degree. 5 or the support members 7 and 9 are provided may also be used.

[Effects of the Invention] For this reason, the present invention reduces the coefficient of friction when moving the table to enable high-speed movement, and when stopping, increases the frictional force to stop the table in a short time to prevent vibration and improve machining. It is possible to provide a table device that can improve accuracy.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the outline of the table device, Fig. 2 is a partially omitted plan view showing the installed state of the sliding friction adding mechanism, and Fig. 3 is a perspective view showing the outline of the table device.
The figure is an explanatory diagram showing the effect. In the figure, 1 is a table device, 2 is a support base, 3.5 is a rail as a guide member, 7 and 9 are support members, 7a and 9a are sliding surfaces, 11 is a moving table, 23° 25 is a sliding friction addition The mechanism includes piezoelectric elements 23a and 25a, and sliding members 23b and 25b.

Claims (1)

[Claims] 1. A table (11) movably supported by a rolling support structure or a static pressure support structure on guide members (3, 5) provided on a support base (2), and the table ( 11)
and drive means (17, 19) for moving the table along the guide members (3, 5), wherein an electro-mechanical conversion is provided between the support base (2) and the table (11). A table device characterized by being provided with a sliding friction adding mechanism (23, 25) for releasably applying appropriate sliding friction by means. 2. The sliding friction adding mechanism is connected to the guide member (3, 5)
A sliding contact surface (7a, 9a) provided on the upper or parallel member (7, 9), and a sliding contact surface (7a, 9a) provided on the table (11) opposite to the sliding contact surface (7a, 9a). The sliding contact members (23b, 25b) are provided on the table (11), and when no voltage is applied, the sliding contact members (23b, 25b) are provided on the table (11).
5b) to form a minute gap (27, 29) between the sliding contact surfaces (7a, 9a), or to bring them into light sliding contact, and when voltage is applied, the sliding contact members (23b, 25b)
) comprises electro-mechanical conversion means for pressing the sliding surface (7a, 9a) with a pressing force corresponding to the applied voltage. . 3. The electro-mechanical conversion means is a piezoelectric element (23a, 25
The table device according to claim 1 or 2, characterized in that it is configured according to a).