JPH0142164B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Application of the Invention) The field of the invention is a method of manufacturing (polishing) a crystal resonator with excellent productivity and vibration characteristics. This invention relates to an oscillating polishing method suitable for continuously changing end face machining.

(Background of the Invention) Since crystal resonators have good resonance characteristics, they are useful as frequency and time reference sources in, for example, communication equipment and digital control equipment. In particular, crystal pieces
AT-cut thickness-shear resonators are often used because their temperature characteristics are flat and their frequency range is in the MHz band. In recent years, due to social trends, there has been a trend toward miniaturization as much as possible while maintaining vibration characteristics.

(Prior Art) FIGS. 5 and 6 are diagrams for explaining one conventional example of this type. FIG. 5 is a diagram showing a cutting direction, and FIG. 6 is a diagram of a crystal piece.

The crystal blank 1 is rotated approximately from the y-axis to the z-axis on the y-z-axis plane, which is the main surface, with the x-axis of the crystal axes x, y, and z as the rotation axis.
It is cut and formed by rotating 35°15′. The new axes created by rotation are the y' and z' axes (Figure 5). and,
The main displacement direction of thickness shear vibration is x of crystal piece 1
Since it is in the axial direction, the x'-axis direction is reduced and the entire structure is elongated in the x-axis direction. In addition, in the x-axis direction, both ends are processed to be thinner than the center to prevent vibration energy from leaking, thereby suppressing an increase in effective resistance and generation of unnecessary vibrations. For example, bevel processing (FIG. 6a) in which the end portion is made into a straight or curved inclined surface (straight line or curved surface), or convex processing (FIG. 6 (b) in which the entire end portion is made into a convex lens shape) is performed. By doing this, it is possible to obtain, for example, a crystal blank having a length in the x-axis direction of 5 to 10 mm and a width in the z'-axis direction of about 1 to 2 mm.

(Problems with the Prior Art) However, in the above-mentioned crystal resonator, ridge angles (ridge lines) are always produced even in bevel processing and convex processing. Furthermore, due to the existence of this ridge, it is not always possible to sufficiently reduce the effective resistance or prevent the generation of unnecessary vibrations. For this reason, it is desirable to eliminate all the ridges of the crystal blank 1, but in reality, the edges of the main surface of the crystal blank 1 are brought into contact with a curved plate called an R plate and polished individually. Must. However, since the overall shape of the crystal piece 1 is very small, there is a problem in that the polishing itself is difficult and cannot be industrially mass-produced. Further, there is a similar problem in that the crystal piece cannot be mass-produced when the crystal piece is shaped like a disk and its diameter is, for example, 10 mm or less.

Therefore, the present invention focused on so-called barrel polishing, which is generally used for deburring, rounding, etc., and expected mass production using this method. Incidentally, in barrel polishing, as shown in FIG. 7, a workpiece 3 and a polishing agent, media, a large amount of water, and a compound 4 are usually accommodated in a rotatably driven, for example, hexagonal container 2. Then, as the container 2 rotates, the contents such as the water and the workpiece rise along the inner wall of the container, and these objects suddenly slide down like an avalanche from the rising point into a fluidized layer (A-B in the figure). ), the abrasive taken into the media polishes the entire surface of the workpiece 3 due to the relative movement of contact between the workpiece 3 and the media that occurs between the fluidized beds. In order to prevent damage caused by collision of the workpiece 3 against the inner wall of the container due to the fluidized bed, an elastic body 5 is usually placed on the inner wall of the container.

However, in this type of barrel polishing, when the workpiece is a crystal piece, it is extremely difficult to control the amount of machining and there are large variations.In particular, since polishing is performed not only on the edge angle but also on the entire surface, the overall shape is Due to the reduction in size, sufficient end face processing cannot be performed. Further, since the approximate resonance frequency is determined by the external shape, particularly the thickness, barrel polishing, in which the thickness direction is polished in the same way as the outer periphery, is extremely inconvenient and cannot be used directly. In addition, in addition to the polishing agent, large amounts of water, media, compound, and elastic material for the inner wall of the container are required, which poses a problem in terms of cost.

(Objective of the Invention) The present invention is suitable for end face processing of small-sized crystal blanks, allows for mass production in particular, facilitates control of the amount of processing, and further improves vibration characteristics by reducing the influence on the resonance frequency. The purpose of the present invention is to provide a method for polishing a crystal resonator.

(Solution Means) The present invention accommodates a crystal piece together with an abrasive in a metal cylinder, and rotates the cylinder to raise the crystal piece and the abrasive along an inner wall and slide them down from a rising point. polishing the crystal piece along the shape of the inner wall by rocking the crystal piece integrally and performing a low-speed relative contact movement between the crystal piece and the abrasive agent interposed between the crystal piece and the inner wall; The solution is that all the edge angles of the crystal piece are formed into curved surfaces whose curvature changes continuously.

(Function of the Invention) The present invention rotates the cylindrical body to raise the crystal piece and abrasive along the inner wall and slide them down from the rising point so that they swing integrally. and are moved relative to each other, and in particular, the outer periphery of the end of the crystal piece facing the inner wall of the cylindrical body is polished by the abrasive interposed therebetween. As a result, the crystal piece will be polished along the shape of the inner wall of the cylinder, and by controlling the rotation time of the cylinder, the curvature of all the edge angles of the crystal piece will change continuously. Can be formed into curved surfaces. An embodiment of the present invention will be described below.

(Embodiment) FIG. 1 is a diagram illustrating an embodiment of the present invention, in which FIG. 1A is an external view of a polishing apparatus, and FIG. 1B is a cross-sectional view of FIG.

The polishing device is provided with a cylinder 7 made of metal such as brass at both ends of a rotating shaft 6 with their centers aligned. Then, it is rotationally driven by a drive source (not shown), for example, by transmitting a belt 8 stretched around a rotating shaft. The cylindrical body 7 houses the contents of a crystal piece 9 elongated in the x-axis direction of the AT cut described above and an abrasive 10 such as carborundum, and is sealed. Then, the cylinder 7 is rotated so that the contents swing integrally along its inner wall. That is, when the cylindrical body 7 is rotationally driven under certain conditions, the above-mentioned contents become, for example, C (solid line) in the figure.
It rises along the inner wall of the cylindrical body 7 from the position shown at D.
(dashed line) is reached. Then, the balance between the frictional force against the inner wall of the cylindrical body 7 and the weight is lost, and the cylindrical body 7 suddenly slides down to the original position shown in FIG. However, when the container slides down, the reaction force causes the contents to move further in the opposite direction from the resting position (i.e., the bottom).

Therefore, in such a case, relative movement occurs between the crystal piece 9 and the inner wall of the cylinder body 7 due to the rocking of the contents within the cylinder body, especially the sliding down of the contents. Since the abrasive 10 is interposed between the crystal blank 9 and the inner wall, low-speed relative contact movement occurs between the abrasive 10 and the crystal blank 9. As a result, crystal piece 9
In particular, the edge portions that contact the inner wall are polished.

Further, the conditions of such a polishing method are greatly influenced by the rotation speed of the cylinder 7 and the amounts of the crystal piece 9 and the polishing agent 10. That is, as the rotational speed of the cylinder 7 increases, the swinging distance of the contents gradually increases. Then, when the limit is exceeded, it becomes shorter again, and the oscillation period becomes shorter in accordance with the rotation speed, and the relative contact movement speed of the contents becomes faster. Furthermore, when the amount of crystal blank 9 input is increased, the pressure of the crystal blank against the inner wall of the cylinder is increased, and the machining speed becomes faster (increasing the amount of edge angle machining), and once the limit is exceeded, the machining speed slows down again. Furthermore, if the amount of the abrasive 13 to be added is increased, the polishing power will not decrease as much and it can be used for a long time. However, by appropriately selecting such processing conditions,
Hundreds to thousands of crystal pieces can be polished at once. A sharp edge angle requires a greater amount of polishing than a blunt edge angle. Therefore, by rotating the cylindrical body 11 for an appropriate period of time, the internal crystal pieces are statistically averaged and polished, and all the ridge angles are removed, for example, as shown in the perspective view of the outline of FIG. 3. It is possible to form a smooth curved surface with a continuously increasing curvature.

In a crystal resonator (crystal blank) produced by such oscillating polishing, the vibration energy of thickness shear vibration is concentrated in the center of the plate surface compared to conventional curved surface bevel processing, etc., so that an extremely good energy trapping effect is obtained. This reduces the effective resistance and suppresses unnecessary vibrations caused by the contour.
Therefore, for example, as shown in the front view of FIG.
2 and fixed with an adhesive, a practically sufficient resonance characteristic can be obtained. In addition, good mechanical strength can be obtained.

By the way, the resonance frequency is 4.194MH (thickness 0.4mm),
A large number of crystal pieces with a length of 9 mm in the x-axis direction, a width of 1.7 mm in the x'-axis direction, and a bevel inner diameter of 6 mm are placed into a
Housed in a 115φ cylinder (brass) to increase rotation speed
When rotated at 90 rpm, the oscillation period of the crystal piece was about 1 second, and after about 80 hours, each crystal piece could be formed into a curved surface with continuously increasing curvature as described above, and as a result, The effective resistance was reduced and unnecessary vibrations were suppressed. However, the number of crystal pieces at this time is 200 pieces/1cm for the length of the tube, and the carborundum is 4g/1cm for the mesh number 320 to 1200.
It is. Further, the side surface (z' plane) of the crystal piece is tilted by 4 to 6 degrees.

Similar results were also obtained when the crystal piece was shaped like a disk. That is, the resonant frequency
4.194MHz, outer diameter 8.7φ, thickness 0.4mm, bevel inner diameter
When a crystal piece with a diameter of 5.7φ was put into a cylinder and subjected to rocking polishing, all the edge angles were formed into curved surfaces with continuously increasing curvature after about 100 hours. However, as mentioned above, the length of the cylinder is 100mm, the inner diameter is 115φ, and the carborundum is 4g/1 as mesh number 320 to 1200.
cm, and the number of crystal pieces is 40 pieces/1 cm.

In the above description, an experimental example was shown in which the crystal piece was beveled, but a flat crystal piece without bevel processing can also be applied by setting the processing conditions. And basically, x
It can be applied to any size and shape, regardless of whether it is a rectangular shape elongated in the axial direction or a disk shape with a small diameter.

(Effects of the Invention) The present invention accommodates a crystal piece together with an abrasive in a metal cylinder, and rotates the cylinder to cause the crystal piece and abrasive to rise along an inner wall and slide down from a rising point. The crystal piece is polished along the shape of the inner wall by performing relative contact movement at a low speed between the abrasive agent interposed between the crystal piece and the inner wall and the crystal piece. Since all the edge angles of the crystal blank are formed into curved surfaces with continuously changing curvatures, it is suitable for end face processing of small-sized crystal blanks, and can be especially mass-produced, making it easy to control the amount of processing.
Moreover, it is possible to provide a method for polishing a crystal resonator that reduces the influence on the resonance frequency and improves the vibration characteristics, and its practical value is extremely high.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining one embodiment of the present invention, Fig. 1a is a diagram of a polishing device, Fig. 1b is a sectional view showing the polishing action, Fig. 2 is a schematic diagram, and Fig. 3 is a diagram showing the same embodiment. FIG. 4 is a diagram of a crystal piece according to an example, and FIG. 4 is a diagram of a holding structure of a crystal resonator. FIG. 5 is a diagram showing the cutting direction of the crystal blank, FIGS. 6 a and b are diagrams of the crystal blank, and FIG. 7 is a sectional view showing the effect of barrel polishing. 7...Cylinder, 9...Crystal piece, 10...Abrasive.

Claims (1)

[Scope of Claims] 1. A crystal piece is housed together with an abrasive in a metal cylinder, and the cylinder is rotationally driven to raise the crystal piece and the abrasive along an inner wall and slide down from a rising point to be integrated. The crystal piece is polished along the shape of the inner wall by performing relative contact movement at a low speed between the abrasive interposed between the crystal piece and the inner wall and the crystal piece, and the crystal piece is polished along the shape of the inner wall. A method for manufacturing a crystal resonator, characterized in that all edge angles of a crystal piece are formed into curved surfaces whose curvature changes continuously. 2 The crystal piece is rotated approximately 35°15' from the y-axis to the z-axis with the x-axis of the crystal axes x, y, and z as the rotation axis, and the newly generated y- and z-axes are When the z' axis is defined as the z' axis, it is elongated in the x axis direction, the y' axis is thick, the x-y' axis plane is the main surface, the length in the x axis direction is 5 mm to 10 mm, and the fundamental wave vibration is 15 MHz or less. Claim 1 characterized in that the first claim is excited by
2. Method for manufacturing a crystal resonator as described in Section 1.