US2469563A - Lapping machine - Google Patents

Description

Ma 10; 1949. R, K. KINA'RD 2,469,563

mrrme MACHINE FiledApril 4, 1947 3 Sheets-Sheet 1 FIG.

IN l/EN TOR R. x. mmno ATTORNEY R. K- KINARD LAPPING MACHINE May 10, 1949 Filed April 4, 1947 3 Sheets-Sheet 2 FIG. 2

a a g 4 3 m F INVEN TOR,

. n. min/MR0 47 TORNEY y 1949. R. K. KINARD 2,469,563

I LAPPING MACHINE- Filed April 4, 1947 :5 Sheets-Sheet s FIG. 4.

INVENTOR R. K/NARD BYIM .4 r ran/var Patented May 10, 1949 UNITED STATES PATENT OFFICE LAPPING MACHINE Robert K. Kins-rd, Allentown, Pa, designer to.

Western Electric Company, Incorporated, New York, N. Y;, a corporation of New York Application April 4, 1947, Serial No. 739,437

scams. 51-120) extremely thin quartz crystal slices for use in electrical arts.

For various uses in electrical arts, it is necessaryto employ small slices of crystalline quartz having their fiat faces formed parallel with each other to an extreme degree of accuracy and the slices being further formed to a predetermined thickness with great accuracy. Such slices are rough cut and formed in-various ways and are subsequently ground or cut to approximately the desired thickness. The final step of lapping these nearly finished slices down to the finished product is a difiicult task, especially on a production basis. The most popular method of lapping quartz crystal slices includes a carrier or lapping nest comprising a metal disc oscillated between lapping plates supplied with an abrasive material, the carrier or nest having apertures therein to receive and control the movement'of the slices between the lapping plates. The carrier or lapping nest of necessity had to be thinner than the final thickness desired for the quartz slices and also sufiiciently durable to be driven to move the numerous quartz slices between the lapping plates. 7

Recently quartz crystal slices of a finer thickness than heretofor required have been requested for electrical units. approximately 25 microns and the crystal slices of this thickness could not be produced by the present lapping machines and methods. A lapping nest of a thickness suitable to accommodate these slices would not be suiliciently durable to be driven between the conventional lapping plates.

An object of the invention is to provide an improved apparatus for simultaneously lapping both sides of each of a plurality of thin objects to produce, to a high degree of accuracy, parallel plane faces spaced a predetermined distance apart.

With the above and other objects in view, the invention comprises a, lapping machine.including an element formed with a plurality of lapping surfaces surrounded by a retaining element and cooperating with a relatively movable'lapping plate to lap objects disposed on the lapping surface. More specifically, the lapping machine includes a stationary element having a circular arrangement of vertically extending lapping members, cylindrical in general contour,'equallyspaced from each other and having hardened gridded upper surfaces. A retaining element an- This' new thickness is 2 nular in general contour has a series of openings to receive the projections, the upper surface of the retaining element being positioned a given distance above and parallel with a common plane in which the gridded surfaces are disposed, this distance being less than the final thickness of the objects. A lapping plate is supported loosely.

upon the objects to be lapped and is oscillated relative to the lapping members, additional means being provided to create an additional motion in the lapping plate to vary the portions of the gridded under surface thereof which come in contact with .the objects being lapped.

Other objects and advantages will be apparent from the following detailed description when considered in conjunctionwith the accompanying drawings, wherein v Fi 1 is a vertical sectional species of the invention;

Fig. 2 is a fragmentary top plan view. of the structure shown in Fig. 1, portions thereof being broken away; I

view of one of the Fig. 3 is a fragmentary sectional view taken along the line 3-8 of Fig. 2; and

Fig. 4 is a vertical sectional view of another species of the invention.

Referring now to the drawings, attention is first directed to Figs. 1 to 3, inclusive. The species of the invention shown in'these figures includes a supporting frame It having a saucer shaped table II mounted thereon with central bosses l2 and Il positioned about a central aperture [5 for a shaft l8. Anv annular element l8 formed with a plurality of cylindrical lapping members is formed integral therewith is mounte'd centrally of the table 'I I.

The upper surfaces of the lapping members I! are hardened and ground to lie in a common plane, these surfaces also being gridded as at 20. A retaining element 2|, annular ingeneral contour has a series of apertures 22 therein substantially equal in diameter to the diameter of each of the lapping members is to receive these members as illustrated in Figs. 1 and 2. The

thickness of the retaining element 2! is slightly der surface I of the lapping plate is hardened and gridded in the conventional manner as indicated at 21.

The driving means for the lapping plate 25 includes the shaft II which is journalled in bearin s 22 and 30 within the bosses l2 and i4 and the central aperture I! of the table ii. The shaft i is further supported by a. thrust bearing 2| disposed in a lateral member 22 of the main frame I0. A beveled gear 33 mounted upon the shaft i0 is driven from a main drive shaft 24 through a beveled gear 25. A collar or head 26 mounted upon the upper end of the shaft i8 carries a pin 21 eccentrically mounted to move in acircular path, the diameter of which is substantially equal to the diameter of each of outwardly in this direction during each cycle of I movement. The roller 4| is supported by an arm 42, slidably disposed in an aperture 43 of a holder 44, limited in its movement by a pin 45 and normally urged outwardly by a spring 46, the spring functioning to cushion the contact between any of the teeth 40 of the lapping plate and the roller 4 I.

Prior to considering the operation of the machine, attention is directed to the objects 50 which are to represent quartz crystal slices to be reduced in thickness by this machine to approximately 25 microns. The objects 50 in reality are slightly thicker than the required final dimension beforethey are placed in their respective pockets on the lapping members it. It will be observed therefore that the dimensions of the objects 50, the distances between the upper surfaces of the lapping members I! and the retaining element also to illustrate the existence of parts 50 within these pockets. The lapping machine as illustrated in the drawings is of necessity smaller than the actual machine. It would not be possible to show the objects 52 in the drawings with their exact thickness and the same applies to the illustration of the depth of the pockets receiving the objects and the space between the lapping surfaces.

In preparing the machine for operation the lapping plate 25 is removed and an object, namely, a quartz crystal slice II, is placed within each of the pockets. that is, the apertures 22 above the gridded surfaces of the lapping members l9. The lapping plate 25 is then carefully lowered in place and the conventional abrasive material is supplied in the usual manner to the lapping areas during operation of the machine. The saucer shaped formation of the table if is to receive the abrasive material and-direct it in the usual man-. ner to the supply (not shown). The machine is then set in operation by driving the shaft 34, causing rotation of the shaft l 6 through the gears 22 and 25, causing the pin 21 to move in its circular path about the centeriine of the shaft it to oscillate the lapping plate 22 relative to the lapping members it; This action will cause both lapping surfaces adjacent each object II to grind away the surfaces of the object through the assistance of the abrasive material, maintaining the surfaces parallel with each other. Each time the lap ng plate 25 approaches the roller H, the roller will engage one of the teeth and act as a fulcrum for the lapping plate during the continued movement applied to the lapping plate through the pin 21, creating intermittent adjustments in the lapping plate relative to the lapping portions I9.

The species ofv the invention shown in Fig. 4 is identical in every detail to that shown in Figs. 1 and 2 with the exception of the driving means for the lapping plate, like reference numerals being applied to the like parts. The lapping plate in this figure is given the reference numeral 65, although it differs from the lapping plate 25 only in its connection with the driving means. The driving means in this instance includes a hollow shaft 56 journalled in a suitable bearing 51 and keyed to a pulley 58 driven by a belt 59 from a power means (not shown). If desired, the driving means may include a drive shaft operatively connected to the shaft 88 through the aid of gears as illustrated in Fig. 1. An arm 60 is keyed to the upper end of the shaft 58 and supports a pin iii in the form of a shaft. the lower end of which is journalled in a-bearing 82 of the arm 60. The axes of the shafts I6 and H are parallel with each other and disposed a given distance apart which issubstantially equal the radius of the lapping members it. A gear 64 fixedly mounted upon the pin or shaft 8| interengages a pinion 85 which is mounted upon the upper end of a fixed shaft 66 extending through the hollow shaft 56 into an apertured portion 21 of a lateral member 68 of the mainframe ill. The aperture 69 is internally splined to receive the splined end 10 of the shaft 66. Returning now to the shaft 6|, it will be observed that, the upper end thereof is grooved at 12 to receive an apertured end of an arm "which is pivotally connected at 14 to the shaft iii. The outer end of the arm 13 is bent downwardly at right angles as indicated'at l5 and is receivable in an aperture 18 in the lapping plate 55.

During operation of this species of the invention, through the driving of the belt 52, the hollow shaft 58 will be rotated about the stationary shaft 86 moving the pin or shaft ii in a circuitous path to impart a circular or oscillating motion to the lapping plate 55 relative to the lapping members l9 and the objects II. As the arm carries the shaft Si in its circuitous path, the gear '64 travels about the pinion I and in engagement therewith to cause the shaft H to rotate slowly. In thisv manner,- there is a continuous change in the portions of the gridded surface 18 of the lapping plate 55 which come in contact with the various objects 50 to cause uniform wear on the lapping surface 18. Through this driving mechanismthe same circular motion is imparted to the lapping plate 55 as is applied to the lapping plate 25 of the structure shown in Figs. 1 and 2. The .only difference in the motions of the two lapping plates is that the adjusting motion of the lapping plate 55 is continuous while the adjusting motion of the lapping plate 25 is intermittent.

With these structures, their principal features being identical in the provision of a plurality of fixed position lapping members with retaining pockets for the individual objects or thin quartz crystal slices, it 'is possible to reduce the thickness of these objects to fine dimensions while maintainingtheir faces or opposing surfaces substantially parallel. sions attained through this lapping process through the aid of the species of the lapping machine is made possible mainly through the sturdy structures, forming the pockets and controlling the positioning of the quartz slices within their individual lapping areas. Furthermore, the lapping members, being integral with their base l8, may be simultaneously reconditioned and their surfaces maintained in a common plane. The retaining element 2| may be reconditioned in a similar manner grinding the upper surface thereof to maintain the depth of the pockets surrounding tliegridded surfaces 20. Furthermore, the depth of the pockets may be varied by the introduction of shims between the abutting surfinal thickness to which articles disposed individually in the pockets are to be lapped, a lapping element positioned above the lapping members and having a gridded under surface to The fineness in the dimenfaces of the retaining element 2| and the base l8 of the lapping members l9.

Although specific improvements of the invention have been shown and described, it will bev opposite faces of thin articles comprising a plu- I rality of lapping members disposed in circular arrangement at spaced positions with respect to each other and having upper surfaces to receive articles to be lapped, -means surrounding the lapping members to form retaining pockets above the upper surfaces of their respective lapping members of like depths less than the final thickness to which the articles are to be lapped, a lapping element positioned above the lapping members and having an under surface to engageall the articles simultaneously, and means' to rest on all the articles in the pockets simultaneously, and means to move the lapping element relative to the lapping members to lap the articles as they are individually retained in their respective pockets.

3. An apparatus for simultaneously lapping opposite faces of thin articles comprising a stationary support, an annular element mounted on the support and having integral lapping members circular in cross-section disposed in spaced positions circularly about the upper surface ofthe annular element with their upper surfaces gridded and positioned in a given plane parallel with the upper surface of the annular element, an annular retaining member, having a circular arrangement of cylindrical apertures therein to receive their respective lapping members, mounted on the upper surface of theannular element and being of greater vertical dimension than the lapping members whereby retaining.

pockets formed in the apertures extend above the gridded surfaces of like distances less than the final thickness to which. articles disposed indi-.

vvidually inthe pockets are to be. lapped, a

lapping element positioned above the lapping members and having a gridded under surface to rest on all the articles inthe pockets simultaneously, spaced projections mounted on the periphsupport to be engaged by certain of the projecmove the lapping element about.an axis in .a I

path the diameter of which is substantially equal the diameter of each of the upper surfaces of the lapping members.

2. An apparatus for simultaneously lapping.

opposite faces of thin articles comprising a stationary support, an annular element mounted on the support and having integral lapping members tions during each cycle of movement of the lapping element to impart further movement to the lapping element ,to vary the portions of the under surface of the lapping element engaging the articles to cause uniform wear on the said surface.

' ROBERT K. KINARD.

REFERENCES CITED,

The following references are of record in the file of this patent

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