JP2000158320A - Chamfering method for crystal piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply chamfering of a continuous change in curvature to a crystal piece and to simplify management of a machining pot, machining time management, crystal piece management, machining process, and such. SOLUTION: In a chamfering method for a crystal piece wherein the crystal piece has a flat part in a center part and chamfering curvature becomes continuously smaller from the flat part toward the exterior, chamfering of the crystal piece is performed by putting the crystal piece inside a machining pot having a section surface perpendicular to a rotary shaft elliptically shaped, and rotating the machining pot.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for chamfering a crystal blank.

[0002]

2. Description of the Related Art Conventionally, crystal blanks have been chamfered by putting a crystal blank and an abrasive into a processing pot having a spherical inner surface and rotating the processing pot. Since the chamfered shape of the crystal blank follows the curvature of the pot for processing, the radius of the pot for processing is set in accordance with the desired chamfered shape of the crystal blank. Chamfering is done from the edge,
A flat portion remains in the center. Increasing the amount of chamfer eventually results in a convex shape without flat portions.

[0003] The thickness-sliding quartz resonator (quartz piece) cut out by the AT cut is chamfered as described above for the purpose of confining energy. The thickness sliding oscillator has a relatively low frequency, and the crystal impedance value and the load capacitance characteristics are improved by chamfering. A chamfered edge is referred to as a bevel shape. Preferably, the above-mentioned convex shape is preferable, but it has a disadvantage that the processing time is long.

As a means for further improving the characteristics of the convex shape, a technique has been proposed in which the curvature of the chamfer is gradually reduced toward the end. Japanese Patent Application Laid-Open No. H10-107580 discloses a C-shaped structure having three or more bevels.
I value characteristics, CI value temperature characteristics, CL characteristics (load capacitance characteristics)
Is described as being improved. FIG. 1 is a front view (B) and a top view (A) of a rectangular crystal piece processed by two processing pots having different curvatures. First, the rectangular crystal blank 1 is processed into a convex shape using a large-diameter (R1) processing pot, and then a required amount of chamfering is performed from an end using a small-diameter (R2) processing pot. The ridge line 2 is formed at the boundary between the processing by the small diameter processing pot and the processing by the large diameter part. In this example, the convex processing is performed in two stages.
There is no difference that the boundary can be formed in the same way even if the number of steps is more than one.

[0005]

In order to change the curvature of the chamfered portion of the crystal piece stepwise, a plurality of processing pots having different curvatures must be used, and the processing pots having larger curvatures must be sequentially processed. In addition, the chamfering process is long, and the management of the processing pot, the processing time, the crystal blank, and the like become complicated.

Further, if the curvature of the chamfered portion of the crystal piece is changed stepwise, the portion (boundary) where the curvature changes sharply changes, thereby deteriorating various characteristics of the vibrator. The characteristics of the quartz piece alone are dealt with in the present invention, though it varies depending on the piece supporting structure, etc.). It is preferable to change the curvature continuously, but it has been difficult to realize the processing method using a plurality of processing pots having different curvatures.

[0007]

In a method of chamfering a crystal piece having a flat part in the center of the crystal piece and continuously reducing the chamfer curvature from the flat part toward the outside, the method is perpendicular to the rotation axis. A crystal piece is put in a processing pot having an elliptical cross section, and the crystal pot is chamfered by rotating the processing pot.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a rectangular crystal piece having a radius of curvature of 60 mm at the center in the longitudinal direction and a radius of curvature of 50 mm at the ends.
Shows the elliptical shape to be processed into the convex shape of
= 100 mm, minor axis b = 83.32 mm.

FIG. 3 shows a rectangular quartz piece having a length of 8 mm processed by an elliptical pot of the present invention and a spherical pot having a radius of 60 mm.
FIG. 4 is a table showing dimensions of rectangular quartz pieces when m chamfering is performed and processing is performed using a spherical pot having a radius of 60 mm. FIG. 4 is a graph. FIG. 5 is a perspective view for explaining how to measure the X and Y dimensions on the rectangular crystal piece in FIG. 3. The center point of the upper surface of the convex-type rectangular crystal piece is the origin O, and the X and Y axes are as shown in the figure. Is set.

As can be seen from FIG. 3, the dimensions of the elliptical pot according to the present invention and the dimensions of the two-step processing with R60 + R50 can be made substantially the same except for the end portions.

FIG. 6 is a graph showing a dimensional change of X between 1360 μm and 2800 μm. It can be seen that the Y change amount of R60 + R50 changes rapidly at 2000 μm. On the other hand, the ellipse according to the present invention changes smoothly. It can be seen that the curvature change from the end radius of 50 mm to the center radius of 60 mm is continuous, and that there is no abrupt change in curvature, which is a drawback due to the conventional two-step and three-step bevel processing.

Although the convex shape has been described, a chamfering process in which the curvature is continuously changed by adjusting the thickness and the chamfering time of the rectangular crystal blank is possible even in a shape in which a flat portion is left in the center portion. When the large diameter r1 and the small diameter r2 are determined, the elliptical shape can be determined.

Although the above description has been made with reference to a rectangular crystal piece, the same processing can be performed with a disk-shaped or rectangular crystal piece.

[0014]

According to the present working method, the quartz piece can be chamfered with a continuous curvature change. This eliminates a sharp change in the curvature of the chamfered portion caused by chamfering a plurality of times, and improves and stabilizes various transducer characteristics.

Since a single pot can be used for chamfering a crystal piece with a continuous change in curvature, management of a processing pot, management of processing time, management of a crystal piece, processing steps, and the like can be simplified.

[Brief description of the drawings]

FIG. 1 is a front view (B) and a top view (A) of a rectangular crystal blank processed by two processing pots having different curvatures.

FIG. 2 shows that the curvature of the central portion in the longitudinal direction of the rectangular crystal piece is set to a radius of 6;
0mm, elliptical shape for processing the end into a convex shape with a radius of 50mm

[FIG. 3] A rectangular quartz piece having a length of 8 mm is processed by the elliptical pot of the present invention, a spherical pot having a radius of 60 mm. Table showing the dimensions of the rectangular crystal vibrating piece when processed

FIG. 4 is a graph of the table of FIG. 3;

FIG. 5 is a perspective view illustrating how to measure X and Y dimensions on a rectangular crystal blank.

FIG. 6 is a graph showing a dimensional change between 1360 μm and 2800 μm for X.

[Explanation of symbols]

1 Rectangular crystal blank 2 Ridge line a Long diameter b Short diameter O Top center point (origin) of convex rectangular crystal blank

Claims (1)

[Claims] 1. A method for chamfering a crystal blank having a flat portion in the center of the crystal blank and continuously reducing the chamfer curvature outward from the flat portion, wherein a cross section orthogonal to the rotation axis has an elliptical shape. Put the crystal piece into the processing pot with
A method for chamfering a crystal blank by rotating the processing pot, thereby chamfering the crystal blank.