JP3619293B2 - Sealed ultra-precision fine motion device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is mounted on an XY stage such as a precision tool for a machine tool in a precision processing machine or a printing machine, or a dicing apparatus for processing a magnetic head, a semiconductor exposure apparatus, etc., and has a large generating force and a minute movement. The present invention relates to an ultra-precision positioning device.
[0002]
[Prior art]
Piezoelectric elements incorporated in conventional positioning devices are strong against compressive forces but weak against bending and pulling forces, and in order to obtain a large generated force, piezoelectric elements with a large cross-sectional area in the device However, the manufacturing method has a drawback that it is difficult and expensive. For this reason, one piezoelectric element incorporated in the apparatus is often arranged with a small cross-sectional area, and cannot be used where a large generating force is required.
[0003]
In addition, the device that incorporates the piezoelectric element has a structure in which the output member penetrates the tip cap, so that the seal of the shaft sliding part is not perfect, and the intrusion of water vapor in the air is blocked in a long-term high-humidity environment. There was a disadvantage that it was not possible.
[0004]
[Problems to be solved by the invention]
The conventional apparatus has the following problems.
(1) When used in a place where a large generated force is required, a plurality of conventional devices must be used, and the generated force of only one device is insufficient.
(2) When obtaining a large generated force by arranging a plurality of piezoelectric elements in a metal case, the desired generated force cannot be obtained unless the height of the arranged piezoelectric elements is uniform, and a plurality of the piezoelectric elements are arranged. In this case, it is difficult to adjust the height of each piezoelectric element.
[0005]
The purpose of the ultra-precision fine movement device of the present invention is to solve the above-mentioned problems, and it is possible to obtain a large generated force with one device and completely block water vapor in the air, and to achieve a piezoelectric element. An object of the present invention is to provide a device that is strong against pulling force and bending force, which are disadvantages of the above.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, a sealed ultra-precision fine movement device according to the present invention has a plurality of piezoelectric elements arranged in parallel, a support plate is provided at each end of the piezoelectric element, and a ball plan is provided on one of the support plates. A sealed ultra-precision fine movement device comprising a jar, pre-pressing a piezoelectric element between the support plates , and provided with a pre- load support column capable of adjusting the pre- load, and sealed in a metal container having a telescopic structure.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a first embodiment of the present invention. 1 is a metal case (cylinder) composed of a stainless steel elastic metal bellows cap 9 and a mounting flange 15 to which a mounting member 10 is welded in advance by electron beam welding. The plurality of piezoelectric elements 1 are supported by the first support plate 3, the second support plate 11, and the preload strut 5 in the body. Further, the joining of the metal bellows cap 9 and the mounting flange 15 is mainly constituted by sealing by screwing with a bolt 16 via a packing member 12 such as an O-ring or metal. This will be described in detail below.
[0008]
A hemisphere in which a receiving portion 21 of a lower plate 7 attached to the piezoelectric element 1 is provided on the ball plunger 8 by pushing a plurality of ball plungers 8 provided on the second support plate 11 from below the second support plate 11. The piezoelectric element 1 is pushed in via the first support plate 3 so that the hemispherical member 4 attached to the piezoelectric element 1 is in contact with the receiving portion 20 provided on the first support plate 3 so that the height of the plurality of piezoelectric elements is constant. The generated force of each piezoelectric element can be taken out, and a large generated force can be output from the output member 2.
[0009]
The hemispherical member 4 is fixed to the upper plate 6, the receiving portion 20 is provided on the first support plate 3, and the receiving portion of the ball plunger 8 held on the second supporting plate 11 is an inverted conical or inverted spherical shape. The part 21 was provided on the lower plate 7. The hemispherical member 4, the hemispherical portion of the ball plunger 8, the receiving portion 20, and the receiving portion 21 were made of a high hardness material to prevent deformation and wear. The hemispherical member 4 and the receiving portion 20 provided on the first support plate 3 cause the hemispherical member 4 and the receiving portion 20 to be separated from each other even when a tensile force higher than the preload is applied. Even if a bending force is applied, the hemispherical member 4 relaxes the bending force, resulting in a structure strong against the bending force.
[0010]
Between the metal case 9 and the piezoelectric element 1, a preload strut 5 made of a spring material such as phosphor bronze, stainless steel, or brass is disposed. The preload strut 5 is provided with screw portions at the upper and lower portions and a meandering spring portion at the center thereof, and the position, spring constant and length of the spring portion are selected as necessary. The preload strut 5 is stopped by a fixing nut 17 fixed by the first support plate 3, and a preload (compression force) applied to the piezoelectric element 1 can be arbitrarily adjusted by an adjustment nut 14 below the second support plate 11. .
[0011]
The voltage applied to the piezoelectric element 1 is performed by providing the mounting flange 15 with a current introduction terminal 13 covered with insulating glass, and the current introduction terminal 13 is even sealed with the attachment flange 15 by glass fusion. The current introduction terminal 13 in the mounting flange 15 is soldered to the plus and minus lead wires of the piezoelectric element 1 and covered with a heat shrinkable tube. The current introduction terminal 13 on the outer side of the mounting flange 15 is embedded with a water-repellent resin and has a coating that does not condense in a high humidity environment.
[0012]
Next, the operation of this embodiment will be described. A table (not shown) is screwed onto the tap 19 of the output member 2 and a moving object is placed on the table. At this time, although a bending force is applied to the apparatus, the hemispherical member 4 attached to the piezoelectric element 1 relaxes the bending force, and the bending force is not directly applied to the piezoelectric element 1, so that the piezoelectric element 1 can be prevented from being damaged. Further, even if a large pulling force greater than the preload is momentarily applied, the hemispherical member 4 and the receiving portion 20 are separated, and the pulling force is not transmitted to the piezoelectric element 1.
[0013]
Piezoelectric element 1 uses a laminated piezoelectric element having a structure in which positive and negative internal electrodes are alternately laminated, piezoelectric ceramics and electrodes are integrally fired, and external electrodes are connected to the end face of the piezoelectric element, and a high direct current (2 KV / mm) was used. When a voltage of 140 V is applied using a piezoelectric element having a shape of 5 (L) × 7 (W) × 40 (H) mm, the piezoelectric element overcomes the preload and extends about 40 μm to push up the upper plate. .
[0014]
The generated force of the piezoelectric element 1 is 100 kgf, but when a plurality of piezoelectric elements 1 are incorporated in this device and the height of the piezoelectric element 1 is made uniform by the ball plunger 8 installed in the device, For example, if four piezoelectric elements 1 are incorporated, the weight becomes 400 kgf. In this way, a large generated force can be obtained, and in the case of a load up to this generated force, positioning can be performed without hindering the expansion of the piezoelectric element 1.
[0015]
A plurality of piezoelectric elements 1 are arranged in the apparatus, and a plurality of ball plungers 8 provided on the second support plate 11 are pushed from the lower part of the second support plate 11 to receive the lower plate 7 of the piezoelectric element 1. The height variation of the piezoelectric element 1 can be made constant by pressing the portion 21 with a hemisphere attached to the ball plunger 8. By doing so, the displacement amounts of the plurality of piezoelectric elements 1 become constant, and the tips of the plurality of piezoelectric elements 1 are aligned to push the output member 2, so that the output member 2 pushes the table parallel to the output shaft and bends it. Hard to apply force. As a result, a generation force several times that of the case where there is one piezoelectric element can be obtained, and the bending force is not easily applied to the piezoelectric element 1, so that it is difficult to break.
[0016]
FIG. 2 shows a second embodiment of the present invention. The difference from FIG. 1 is that a metal diaphragm cap 18 is used, and a hemispherical member 4 is fixed to the center of the upper portion of the support plate 3, and a joint portion with the upper plate 6 bonded to the piezoelectric element 1 is provided at the lower portion. It is in place. The hemispherical member 4, the hemispherical portion of the ball plunger 8 and the receiving portion 21 were made of a high hardness material to prevent deformation and wear. This also has a structure that is strong against pulling force and bending force, which are disadvantages of the piezoelectric element 1 as in FIG.
[0017]
3 and 4 are cross-sectional views when four or three piezoelectric elements 1 are arranged. In this way, an arbitrary number of piezoelectric elements 1 can be placed in the apparatus, and an arbitrary generated force can be obtained.
[0018]
【The invention's effect】
The present invention is configured as described above, and a required number of piezoelectric elements are arranged in parallel according to the target generated force, and the height variation of the piezoelectric elements generated at this time is held on the second support plate. By adjusting the jar, the generated force of several times that of the fine movement positioning device using one conventional piezoelectric element with a constant height of the piezoelectric element is taken out. In other words, it is possible to position a heavy object several times as large as the conventional one.
[0019]
In addition, even if a large pulling force exceeding the pre-load is momentarily applied, the ball plunger hemisphere member attached to the second support plate is separated from the receiving part of the lower plate, and the pulling force is not transmitted to the piezoelectric element, resulting in damage. do not do.
[0020]
Also, when a heavy object is placed on the stage and directly connected to the output member and driven at high speed, even if a bending force that is not parallel to the output shaft is applied, the hemispherical member relaxes and the bending force is not transmitted directly to the piezoelectric element. Can prevent damage.
[0021]
In addition, the metal cap and the mounting flange are sealed by an electric welding method or a metal seal method, and the electrical introduction terminal portion of the mounting flange is fused with glass and solder via insulating ceramics. It is an ultra-precision fine motion device that can completely block dust and the like, and is durable against humidity and dust.
[Brief description of the drawings]
FIG. 1 shows a longitudinal sectional view of a first embodiment of the present invention.
FIG. 2 shows a longitudinal sectional view of a second embodiment of the present invention.
FIG. 3 is a cross-sectional view when four piezoelectric elements are arranged in parallel.
FIG. 4 is a cross-sectional view when three piezoelectric elements are arranged in parallel.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Output member 3 First support plate 4 Hemispherical member 5 Preload member 6 Upper plate 7 Lower plate 8 Ball plunger 9 Metal bellows 10 Mounting member 11 Second support plate 12 Packing member 13 Current introduction terminal 14 Adjustment nut 15 Installation Flange 16 Bolt 17 Fixing nut 18 Metal diaphragm 19 Tap 20 Receiving part 21 Receiving part

Claims (2)

A plurality of piezoelectric elements are arranged in parallel, a support plate is provided at each end of the piezoelectric element, a ball plunger is provided on one of the support plates, and a preload is applied to the piezoelectric elements between the support plates and a preload is adjusted. Sealed ultra-precision fine movement device characterized by providing a possible preload strut and sealing it in a metal container with a telescopic structure. 2. The sealed ultraprecision fine movement device according to claim 1, wherein a plurality of piezoelectric elements are held in a cylindrical metal cap.

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