JPS61274835A - Precisely minutely movable long-stroke moving table - Google Patents

Abstract

PURPOSE:To precisely move a table on which a workpiece is to be mounted in a horizontal direction by connecting a ball nut to said horizontally moving table with plural leaf springs and maintaining the parellelism of both members. CONSTITUTION:A ball screw 3 is provided in parallel with a horizontally moving table 1, and is rotatably supported by bearings 4, to be driven in its normal rotation and reversing by the action of a DC servo-motor 5 via gears 6', 7'. A transmission arm 7 is fixed to a ball nut 6, and the end part of the arm 7 is opposed to the top surface of the horizontally moving table 1. Both ends of each of a pair of leaf springs 8 are installed to the ball nut 6 and the horizontally moving table 1 respectively. Thereby, both the ball nut 6 and the horizontally moving table 1 allow relative minute displacement in right and left directions maintaining mutually parallel postures, and the rotation of the ball nut 6 around axis is engagedly stopped, effecting a screwing operation.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a moving table device that is improved so that a table on which a work is to be mounted can be moved precisely in the horizontal direction and has a long movement stroke. be.

[Background of the invention]

There are various methods (for example, air cylinders) for horizontally driving a horizontally moving table equipped with rail means for precisely guiding the horizontally moving table.

Chains and sprockets, wires and sheaves, etc.) are well known, but ball screws/nuts and piezo stacks are known as means that can be driven particularly precisely, and each of these has its advantages and disadvantages.

When comparing the two, a ball screw nut can provide a long stroke on the order of centimeters, but it is accompanied by an error on the order of microns.

In comparison, piezo stacks can achieve accuracy on the order of submicrons, but the maximum stroke is about 0.1 shoulder.

Therefore, in order to obtain both a long stroke on the centimeter scale and a precise fine movement function on the submicron scale, a ball screw nut and a piezo stack must be used together.

When trying to configure a long stroke fine movement table using a ball screw/nut and a piezo stack based on conventional technology, a table that is finely moved by the piezo stack is mounted on top of a table that is coarsely moved by the ball screw/nut. It turns out.

If the table has a two-layer structure as described above, the coarse movement table must carry the weight of the fine movement table, so it must have a sturdy structure.

Furthermore, since the weight carried is large, it is difficult to increase the operating speed, and furthermore, in order to cause the ball screw nut to perform a screw feeding operation, the rotation of the ball nut must be stopped by some means.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and is capable of coarsely moving a single horizontally moving table with a long stroke, as well as finely moving it with ultra-high precision, and yet capable of high-speed operation. The purpose is to provide a suitable long stroke fine movement table.

[Summary of the invention]

In order to achieve the above object, the device of the present invention installs a horizontally moving table and a ball screw in parallel, fixes a transmission arm to a ball nut screwed onto the ball screw, and horizontally moves the tip of the transmission arm. a transmission bracket is fixed on the horizontally movable table to face the transmission arm in a horizontal direction;
A piezo stack is interposed and sandwiched between the transmission arm and the transmission bracket, and the ball nut and the horizontal movement table are connected by a plurality of leaf springs, so that minute vibrations in the axial direction of the ball screw of both members are connected. It is characterized in that it supports the parallelism of both members by allowing displacement, and also locks rotation of the ball nut around its axis.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to the attached drawings (plan views).

A horizontally moving table 1 is guided by a cross roller guide 2 in the left-right direction in the drawing.

A ball screw 3 is provided adjacent to and parallel to the horizontally movable table 1, and rotatably supported by a bearing 4. The ball screw 3 is configured to be driven by a DC servo motor 5 through gears 6 and 7 in a forward and reverse direction.

6 is a ball nut screwed onto the ball screw 3.

A transmission arm 7 is constructed and fixed to the ball nut 6, and the tip of the arm 7 is opposed to the upper surface of the horizontally moving table 1.

Both ends of a pair of leaf springs 8 are attached to a ball nut 6 and a horizontally moving table 1. As a result, the ball nut 6 and the horizontal movement table 1 are supported in a mutually parallel posture while allowing a relative minute displacement in the horizontal direction in the drawing, and
Rotation of the ball nut 6 around the axis is locked, and a screw feeding operation can be achieved.

On the other hand, a transmission bracket 9 is fixed on the horizontally movable table 1 and is opposed to the transmission arm 7.

A piezo stack 10 is positioned between the transmission arm 7 and the transmission bracket 9, and a tension spring 1 is placed between the transmission arm 7 and the transmission bracket 9.
1 is interposed and engaged to apply clamping pressure to the piezo stack 10.

In the table device configured as described above, when the DC servo motor 5 is operated with the piezo stack 10 not expanded or contracted, the ball screw 3 rotates and the ball nut 6 is threaded. Accordingly, the transmission arm 7 fixed to the ball nut 6 moves in the left-right direction in the figure.

When the transmission arm 7 moves to the right in the figure by the same dimension, the transmission arm 7 pushes the transmission bracket 9 to the right in the figure by the same dimension via the piezo stack 1o, and moves the horizontally moving table 1 to the right. Make it run.

Further, when the transmission arm 7 moves to the left in the figure by the dimension, the transmission arm 7 pulls the transmission bracket 9 to the left via the tension spring 11, moves the transmission bracket 9 to the left by the same dimension, and moves the horizontal movement table 1. drive to the left.

In this way, the horizontally movable table 1 has a long stroke (on the order of centimeters) by means of ball screws and nuts.
is coarsely operated with precision (on the order of microns) by means of ball screws and nuts.

After the coarse movement described above, when the piezo stack 10 is electrically controlled to expand and contract, the horizontal movement table 1 is driven in the horizontal direction with the precision (submicron order) of the piezo stack 10.

As the piezo stack 10 expands and contracts, the tension spring 11 expands and contracts while applying a substantially constant clamping pressure to the piezo stack 10, causing the horizontal movement table 1 to move slightly as the piezo stack 10 expands and contracts.

Further, the leaf spring 8 is slightly bent as the piezo stack 10 expands and contracts, allowing relative displacement between the ball nut 6 and the horizontally moving table 1 while maintaining the horizontality of both members, and maintaining the axis of the ball nut 6. Locks rotation around the center.

As is clear from the above-mentioned structural functions, the table device of this embodiment has a structure including a single horizontally movable table 1, and since the weight of the table and the weight of the piezo stack are not applied to the ball screw nut, the ball screw・The nut is light and smooth and can operate at high speed.

〔Effect of the invention〕

As detailed above, according to the device of the present invention, with a simple configuration consisting of a single table, it is possible to coarsely move the single table with a long stroke, and also to make fine movements with ultra-high precision. Moreover, it has an excellent practical effect of being able to operate at high speed.

[Brief explanation of the drawing]

The drawing is a plan view showing an embodiment of the long stroke fine movement table of the present invention. 1... Horizontal movement table, 2... Cross roller guide, 3... Ball screw, 5... DC servo motor,
6...Ball nut, 7...Transmission arm, 8...
leaf spring. 9...Transmission bracket, IO...Piezo stack,
11...Tension spring.

Claims (1)

[Claims] A horizontally movable table and a ball screw are installed in parallel, and a transmission arm is fixed to a ball nut screwed onto the ball screw so that the tip of the transmission arm faces the upper surface of the horizontally movable table. A transmission bracket is fixed to and horizontally opposed to the transmission arm, a piezo stack is interposed and sandwiched between the transmission arm and the transmission bracket, and a plurality of the ball nuts and horizontally movable tables are mounted. The invention is characterized in that it is connected by two leaf springs, allows minute displacement of both members in the direction of the axis of the ball screw, supports the parallelism of both members, and locks the rotation of the ball nut around its axis. A long stroke moving table that can be operated precisely.