US3321868A

US3321868A - Device for grinding a group of lens-like quartz resonators

Info

Publication number: US3321868A
Application number: US383204A
Authority: US
Inventors: Kogan Mark Naumovich; Kibirev Sergei Nikolaevich
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-07-16
Filing date: 1964-07-16
Publication date: 1967-05-30
Anticipated expiration: 1984-05-30

Description

May 30, 1967 M. N- KOGAN ET AL DEVICE FOR GRINDING A GROUP OF LENS-LIKE QUARTZ RESONATORS Filed July 16, 1964 20 FIG. z:

23 F/6.2 F/G. 3

loosely applied on them in United States Patent 3,321,868 DEVICE FOR GRENDING A GROUP 0F LENS-LIKE QUARTZ RESONATORS Mark Naumovich Kogan, Prospect Mira 3-v, Apt. 17,

and Sergei Nikelaevich Kibirev, Kornsomolsky Gorodok 8, Apt. 49, both of Omsk, U.S.S.R.

Filed July 16, 1964, Ser. No. 383,204- 4 Claims. (Cl. 51129) This invention relates to devices for grinding quartz plates and more particularly to devices for grinding a group of lens-like quartz resonators.

It is known that the quality factor (Q) of quartz resonators should not be less than 2- In order to obtain this value of Q it is most favorable to have a double convex or planoconvex lens shape for the quartz plates, because a spherical surface will increase the inductance of the quartz resonators.

However, highly-stable precision quartz resonators of a lens-like double-convex or planoconvex shape should have an orientation angle within and the thickness in points equally spaced from the plate center should not exceed :L-l (when the plate diameter is 26 mm. and the sphere diameter is 300 mm.) with the plate elipse along the diameter of not more than 0.02 mm.

Such high requirements of quartz resonators of double convex or planoconvex shape bring about the necessity to individually finish each resonator. This is a very complicated, laborious and expensive operation and quite unsuitable for mass production because of low efiiciency.

Attempts were made to grind a group of such resonators for instance, by placing several quartz plates with adhered resin balls into a lapping device (a cup-grinder) with a heated mushroom-shaped holder, the quartz plates being positioned in the cup by changing the orientation of the latter. On cooling, the holder with the plates was mounted on a grinding machine spindle whereon it was rotated for grinding.

The tests of such a group grinding method gave no positive results, as in this case it was impossible to obtain uniformly ground surfaces and it was absolutely impossible to check the characteristics of the workpiece being ground. We have successfully solved the problem of grinding a group of precision quartz resonators and have provided a practical embodiment for such grinding.

It is now possible to accomplish a very productive, mechanized and precise group grinding of planoconvex and double convex quartz resonators with diameters of 10 mm. and more and with radii of curvature of more than 100 mm. and wherein said resonators are placed in the lap with pressing devices which are not cemented with the workpieces to be ground.

According to a preferred embodiment of the invention, a group of quartz plate blanks are pressed against the grinding cup surface of a freely rotating lap with a weight the form of a ring-shaped cylinder and a ring secured thereto; both the plates and the weight are placed together with a central rod in an eccentric opening of a ring holder which is loosely in contact with the lapping surface of the cup and is held in the opening of a fixed adapter fastened to the machine.

It is an object of the present invention to provide a device which ensures precise spherical shape of one surface of each group of the quartz plate blanks placed into said device by means of grinding.

It is another object of the present invention to provide a device which ensures precise spherical shape for both surfaces of each group of the quartz plate blanks placed into the foregoing device by means of grinding.

It is still another object of the invention to provide automatic correction of the ground surfaces during the grinding process of the workpiece.

According to the present invention there is provided a device for grinding quartz resonators of a lenslike double convex or plano-convex shape comprising a lap in the form of a cup-grinder and an annular holder loosely placed in the lap for receiving quartz blanks in an eccentrically arranged opening therein, a weight in the form of a ring-shaped cylinder being secured to the holder and bearing via a lower annular part upon the blanks to press the same against the grinding surface of the lap, a central lap rod being received in the holder and loosely resting on the grinding surface of the cup to prevent the blanks from shifting towards the center of the opening.

The annular holder itself is located in the opening of a fixed adapter secured on a bracket.

It is preferable to make the lap out of a soft metal (for instance, bronze) whereas the annular holder and the central rod placed therein may be made out of steel. This will make it possible to improve lapping of the grinding surface and eliminate the need to individually correct the lap cup.

An embodiment of the invention and its operation and advantages will be described in the following description with reference to the accompanying drawing, in which:

FIG. 1 is a side sectional view of a device for grinding a group of quartz resonators;

FIG. 2 shows a replaceable part of the device which is used for manufacturing lens-like quartz resonators of a planoconvex shape; and

FIG. 3 shows a replaceable part of the device which is used for manufacturing double convex-shaped resonators from plano-convex-shaped quartz resonators.

In the drawing there is shown a rotary vertical spindle l of a grinding machine (not shown in the drawing) on which is secured a lap 2 with a concave spherical grinding surface 3 facing upwards.

The radius of the sphere of surface 3 is equal to the radius of the sphere of the quartz resonator surface. Due to the design features of the other parts in the device, the sphere radius is not less than mm.

In the cup of the lap is loosely placed an eccentric annular holder 4, the lower surface 5 thereof being of a convex-spherical shape of the same radius, as that of surface 3.

Reference numbers 6 and '7 designate the axis of symmetry of holder 4, and reference numbers :8 and 9 mark the symmetry axis of the holder opening.

It is apparent from FIG. 1 that the holder opening is arranged eccentrically relative to outer cylindrical surface Ill of the holder.

In the opening of holder 4- is a Weight located in the form of an annular cylinder 11 with a lower annular part 13 secured to the cylinder with screws 12.

Central rod 14- is loosely inserted into the opening of cylinder 11. Rod 14 rests on the spherical surface 3; its lower face surface 15 has a corresponding spherical shape. Workpieces or blanks l6 (i.e. round quartz plate blanks) are arranged in the annular cavity of holder 4 under annular part 13 in such a quantity as can be arranged in one layer.

Rod 14 prevents dislodgement of blanks it from under weight H which presses the blanks, through lower part 13, against grinding surface 3. The surface of part 13 is of a cone shape. The cone angle is dependent on the sphere radius, as well as on the diameter and quantity of the plate blanks to be simultaneously ground so that the plates are in close contact with the cone of part 13.

Cylinder 11 with its lower cone part 13 (as; shown separately in FIG. 2) is designed for maufacturing planoconvex resonators.

In order to decrease frictional resistance resulting from sliding of blank 16 relative to part 13 and to reduce the grinding effect .between the surfaces of these parts, part 13 is made out of a material with very little abrasive property, such as for example, polytetrafluoroethylene.

The annular holder 4- is located in the opening of an adapter 17 secured on machine bracket 18. For controlling grinding process, the adapter may be moved together with the bracket, in the vertical direction (as shown in the drawing by arrows l9), and in the horizontal direction (as shown in the drawing by arrows The quantity of round blanks l6 placed under annular part 13 should preferably be not less than eight in order to distribute more advantageously the pressure on the blanks.

Grinding of the lower surfaces of blanks 16 is carried out in the following order.

First, a pressure pump (not shown in the drawing) is activated to deliver to the cup of lap 2 a conventional grinding suspension used for grinding quartz plates. When lap 2 rotates, adhesion forces make annular holder 4 rotate in adapter 17.

Cylinder 11 with lower cone annular part 13 begins rotating as well but with a slower rotational speed than that of holder 4. Blanks 16 placed under weight 11 and part 13 start rotating each about its own axis due to the speed difference at the opposite points on the blank, as well as about their common axis 8-9 together with cylinder l1 and part 13.

The noncoincidence of axis 945 and axis 7-6 (due to their eccentricity) allows to impart to the blanks some additional motion which provides for uniform grinding of the spherical surface.

When grinding blanks 16, surface 3 of lap cup 2 is automatically corrected with surface 15 of rod 14 and holder 4.

The axis of opening 21 in adapter 1'7 is displaced relative to the rotation axis of lap 2 by a value which provides maximum rotation speed for holder 4 and constant projection of the holder beyond the lap cup.

Upon grinding one surface of blank 16, cylinder 11 and part 13 (FIG. 2) are removed from holder 4. Then blanks 16 (now already resonators of a planoconvex shape) are turned over with the spherical side upright and another cylinder (as shown in FIG. 3) is inserted into the opening of holder 4.

Lower annular portion 22 of this cylinder has a lower concavo-spherical surface 23, the sphere radius of which is equal to that of sphere 3 and consequently, to the radius of the sphere of blanks 16 which are already ground and turned over with their convex sides upright.

Then the grinding of the second, now the lower, surface of quartz blanks 16 (planoconvex resonators) begins.

As a result of this second grinding, quartz resonators of a lens-like shape with a double-convex surface are manufactured.

If only one surface of blanks 16 is ground, then a lenslike quartz resonator with a planoconvex surface is produced.

The present invention can be used for manufacturing precision lens-like quartz resonators with a double-convex or planoconvex surface. Said resonators are employed for frequency stabilization of radio elements and units.

The device can also be utilized for grinding of lens.

It should be pointed out that the present invention provides manufacturing of precision quartz resonators and optical lenses having a thickness of not more than il r at points equally spaced from the plate center within the diameter range of from 10 mm. and more, with the sphere radius from mm. and more, with a frequency diversity of not more than 3 kc. in a group.

Although the present invention is described in accordance with its preferable embodiment, it is apparent that alterations and modifications may be made therein by those skilled in the art without departing from the spirit and scope of the invention as set forth in the appended claims.

We claim as our invention:

ll. A device for grinding blanks to form quartz resonators, said device comprising a rotatable lap having a concave-spherical grinding surface facing upwards, a cylindrical resonator blank holder provided with an eccentrically arranged opening, said resonator having a lower convex-spherical surface in contact with the lap surface, a replaceable cylinder loosely placed in the eccentric opening of the holder for pressing blanks against the lap surface, an annular part having a lower conical surface, said annular part being fastened to the cylinder and adapted for resting on the blanks to urge the same against the lap surface, said cylinder having a bore therein, a cylindrical rod mounted in the bore of the cylinder and provided with a lower convex-spherical surface, said rod restricting the blanks to a position beneath the conical surface of said annular part, and an adapter having an opening receiving the blank holder, said adapter being adjustable vertically and horizontally to control the adapter position and that of the holder.

2. A device as claimed in claim 1 wherein said annular part is constituted of a material of low abrasive property.

3. A device as claimed in claim 1 wherein the opening of said adapter is eccentric with respect to the axisof rotation of the lap, said adapter projecting beyond the lap.

4. A device as claimed in claim 1 comprising a second cylinder for replacement of the first, and an annular part secured to the latter cylinder having a concave-spherical surface for accommodation of the convex surface of ground blanks whereby a double convex surface can be formed on said blanks.

References Cited UNITED STATES PATENTS HAROLD D. WHITEHEAD, Primary Examiner.

Claims

1. A DEVICE FOR GRINDING BLANKS TO FORM QUARTZ RESONATORS,SAID DEVICE COMPRISING A ROTATABLE LAP HAVING A CONCAVE-SPHERICAL GRINDING SURFACE FACING UPWARDS, A CYLINDRICAL RESONATOR BLANK HOLDER PROVIDED WITH AN ECCENTRICALLY ARRANGED OPENING, SAID RESONATOR HAVING A LOWER CONVEX-SPHERICAL SURFACE IN CONTACT WITH THE LAP SURFACE, A REPLACEABLE CYLINDER LOOSELY PLACAED IN THE ECCENTRIC OPENING OF THE HOLDER FOR PRESSING BLANKS AGAINST THE LAP SURFACE, AN ANNULAR PART HAVING A LOWER CONICAL SURFACE, SAID ANNULAR PART BEING FASTENED TO THE CYLINDER AND ADAPTED FOR RESTING ON THE BLANKS TO URGE THE SAME AGAINST THE LAP SURFACE, SAID CYLINDER HAVING A BORE THEREIN, A CYLINDRICAL ROD MOUNTED IN THE BORE OF THE CYLINDER AND PROVIDED WITH