JP2767052B2 - Automatic polishing device for piezoelectric pieces - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic piezoelectric piece polishing apparatus capable of automatically polishing a plate surface of a piezoelectric piece at a desired resonance frequency.

(Technical Background of the Invention) Conventionally, for example, in a manufacturing process of a quartz oscillator, after cutting a rough at a predetermined angle with respect to a crystal axis, processing scratches on a surface layer,
Polishing is performed to a predetermined thickness so as to remove a processing strain and obtain a desired resonance frequency. In particular, in a vibrator of a thickness-shear vibration system, the resonance frequency is determined by the thickness, and therefore must be controlled very accurately.

Therefore, in a polishing apparatus for performing such polishing, it is required that the external shape of the quartz piece has a large effect on characteristics, and in particular, since the thickness determines the frequency, it is required to be able to perform precise polishing without causing defects or the like. I have.

In addition, such a polishing operation, using a cast iron upper and lower stool, relatively polished with an abrasive having a coarse particle,
There is a process called so-called lapping, and a process called so-called polishing in which a polishing plate in which an epoxy resin or the like on the opposite surface of the surface plate is solidified and polishing is performed using an abrasive having relatively fine particles.

FIG. 3 is a perspective view showing an example of a conventional four-wheel drive polishing apparatus for polishing and polishing a piezoelectric piece. Third and fourth drive shafts 2, 3, 4, and 5 are provided.

The lower surface plate 6 is provided on the upper surface of the main body 1. The lower platen 6 is a disc-shaped hard steel material 6A having a through hole in the center.
A polishing plate 6B in which an epoxy resin or the like is solidified is attached to the upper surface of the device, and is rotated by the third drive shaft 4.

A sun gear 7 is provided on the inner periphery and an internal gear 8 is provided on the outer periphery through the center of the lower platen 6. The sun gear 7 is rotationally driven by the second drive shaft 3, and the internal gear 8 is rotationally driven by the fourth drive shaft 5.

An upper surface plate 9 is provided facing the lower surface plate 6. The upper surface plate 9 also has a polishing plate 9B in which epoxy resin or the like is solidified on the lower surface of a disk-shaped hard steel material 9A.
In addition, the driving gear 10 is driven to rotate.

For example, as shown in FIG. 2, the upper platen 9 is held by an air cylinder 11 at the tip of a column 10 protruding from the main body 1 so as to be able to move up and down.

Further, the carrier 13 arranged between the upper and lower platens 6, 9
Is a planetary gear formed with a plurality of holding holes 13A for holding a workpiece 14 to be polished, for example, a crystal piece, and meshes with both the sun gear 7 and the internal gear 8 to perform a planetary operation.

The sun gear 7 and the internal gear 8 are driven to rotate in the same direction, and the upper surface plate 9 and the lower surface plate 6 are driven in opposite directions by a drive mechanism (not shown).

Therefore, when the crystal blank 14 is held in the holding hole 13A of the carrier 13 and the upper platen 9 is lowered, and the sun gear 7, the internal gear 8, and the upper and lower platens 9 and 6 are rotated, the crystal plate 14 becomes upper and lower. Both main surfaces can be polished by being pressed by the lower stools 9 and 6.

The thickness of the carrier 13 is set to be smaller than the thickness of the crystal blank 14, and an abrasive is supplied between the upper and lower platens 9 and 6 to perform a polishing operation.

(Problems of the prior art) However, in such a device, the thickness of the crystal blank is estimated from the polishing time or the number of revolutions of the platen. It is necessary to measure the resonance frequency of the crystal blank, which lowers the operation efficiency and raises the cost.

On the other hand, recently, it is desired to automate the polishing operation in order to improve the operation efficiency and stabilize the quality, and it has been considered that the polishing operation is automatically terminated at a desired thickness.

However, the conventional polishing apparatus as shown in FIG. 3 cannot obtain electrical coupling to the quartz piece being polished, so that its resonance frequency cannot be measured and the end point of the polishing operation is automatically determined. Could not be known.

(Purpose of the Invention) The present invention has been made in view of the above circumstances, and a piezoelectric material capable of accurately grasping the thickness of a piezoelectric piece being polished from its resonance frequency and automatically performing a polishing operation. It is an object of the present invention to provide a piece polishing apparatus.

(Summary of the Invention) According to the present invention, a sun gear is provided at the center of rotation, an internal gear is provided around the sun gear, and the carrier having a large number of holding holes for holding the piezoelectric pieces to be polished is provided by the sun gear. And mesh with the internal gear to make planetary motion,
An upper platen and a lower platen having a non-conductive polishing plate attached to a metal disk on the upper and lower surfaces of the carrier are provided on each of the upper platen and the lower platen. A first electrode solidified by filling a conductive substance with a conductive material, and a second electrode made of a dielectric material. The resonance frequency of the piezoelectric piece connected via this electrode is determined by the control unit as an object. The polishing operation is controlled in comparison with the frequency of the polishing.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to a cross-sectional view of a main part shown in FIG. 1 and an overall perspective view shown in FIG. Note that the same members as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

In the drawing, reference numeral 6 denotes a lower surface plate, on which a polishing plate 6B in which epoxy resin or the like is solidified is provided, and a groove is formed in the polishing plate 6B in a ring shape around the rotation axis. A ring-shaped first electrode 21 is formed by filling and solidifying a soft metal such as a conductive adhesive, a polymer dielectric, lead, tin, or an alloy thereof. It is electrically connected to the steel material 6A.

Reference numeral 9 denotes an upper surface plate, which is provided with a second electrode 22 made of a ferroelectric material by forming a through hole in the polishing plate 9B. The second electrode 22 is provided with an insulating material 23 around the lower platen 6 except for a tip portion facing the lower platen 6 so as to secure electrical insulation from the hard steel material 9A of the upper platen 9. I have.

Then, the second electrode 22 of the upper platen 9 is connected to the control unit 24 via a cable, and the resonance of the piezoelectric piece during polishing sandwiched between the first electrode 21 and the second electrode 22 is performed. The frequency can be measured.

In this case, the resonance frequency of the piezoelectric piece may not be accurately measured due to a noise component, incomplete contact between the electrodes 21 and 22 and the piezoelectric piece, or the like. In such a case, for example, measurement of the resonance frequency is performed a plurality of times on the same piezoelectric piece, and when all the measured values match, it is regarded as a true value, and when different measured values are included, it is regarded as noise. What should I do?

With such a configuration, the holding holes 13A of each carrier 13
When the driving shafts 2, 3, 4, and 5 are rotationally driven by a driving source (not shown) while holding the piezoelectric piece 14, the carrier 13 revolves around the sun gear 7 while rotating. Since the piezoelectric piece 14 slides between the upper surface plate 9 and the lower surface plate 6, the main surfaces thereof can be polished parallel and precisely.

The conductive adhesive for forming the first electrode 21 is made of an epoxy-based adhesive, for example, by kneading a metal such as flaky silver so that the conductive material has conductivity. It is almost equal to the epoxy-based adhesive constituting 6B, so that electrical conduction can be obtained without damaging the piezoelectric piece 14 during the polishing operation.

Also, when a soft metal or the like is used for the first electrode 21,
It is necessary to make its hardness substantially equal to that of the polishing plate 6B.

The ferroelectric used for the second electrode 22 is also made of a material whose hardness is substantially equal to that of the hardened epoxy resin. Therefore, a solidified conductive adhesive made of the same material as the first electrode 21 or a soft metal such as lead or silver may be disposed on the front surface, and a high dielectric substance may be provided on the back, or the polishing may be performed. The plate 9B may be formed by molding a polymer dielectric having close hardness into a column shape.

The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, a description has been given of a case in which polishing is performed by driving four axes. Of course, it can be applied.

(Effects of the Invention) As described in detail above, according to the present invention, by measuring the resonance frequency of the piezoelectric piece during the polishing operation, its thickness can be accurately controlled, and the polishing operation can be automated. It is possible to provide a simple polishing apparatus.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of the present invention, FIG. 2 is a perspective view of the whole of the above embodiment, and FIG. 3 is a cross-sectional view showing an example of a main part of a conventional polishing apparatus. . 1 Body 6 Lower plate 6B, 9B Polishing plate 7 Sun gear 8 Internal gear 9 Upper plate 13 Carrier 14 Material to be polished 21 First electrode 22 ... Second electrode 23... Insulation material 24.

Claims (1)

(57) [Claims] 1. A sun gear disposed at the center of rotation, an internal gear disposed around the sun gear, and a plurality of holding holes for holding piezoelectric pieces to be polished. A carrier that meshes with the planetary motion, an upper surface plate and a lower surface plate in which a non-conductive polishing plate obtained by solidifying epoxy resin is attached to a facing surface of a metal disk disposed on an upper surface and a lower surface of the carrier; A conductive adhesive or a conductive adhesive, such as a lead, tin, or an alloy thereof, which is filled in a through hole formed in one of the polishing plates of the upper and lower lapping plates and solidified to be electrically conducted to the lapping plate. A first electrode made of a conductive material, and substantially the same as the above-mentioned polishing plate disposed in a through hole formed in the other of the polishing plates of the upper platen and the lower platen so as to be electrically insulated from the polishing plate. Hardness dielectric or conductive with hardness almost equal to the above polishing machine A second electrode made of a dielectric material disposed on a front surface thereof, and a control unit for controlling a polishing operation by comparing a resonance frequency of the piezoelectric piece connected via the second electrode with a target frequency. An automatic polishing apparatus for a piezoelectric piece, comprising: