US2382257A

US2382257A - Manufacture of piezoelectric oscillator blanks

Info

Publication number: US2382257A
Authority: US
Inventors: Ramsay Marcus
Original assignee: ALBERT RAMSAY; DORSEY SPENCER H; ERIC G RAMSAY; FORD YOUNG W
Current assignee: ALBERT RAMSAY; DORSEY SPENCER H; ERIC G RAMSAY; FORD YOUNG W; H DORSEY SPENCER; W FORD YOUNG
Priority date: 1943-04-21
Filing date: 1943-04-21
Publication date: 1945-08-14
Anticipated expiration: 1962-08-14

Description

Aug. 14, RAMSAY MANUFACTURE OF PIEZO-ELECTRIC OSCILLATOR BLANKS Filed April 21, 1943 6 Sheets-Sheet l INVENTOR MARCOS EAMM Y.

Y Q 3/ M A TONEY ELECTRIC OSCILLATOR BLANKS Filed April 21,

M. RAMSAY 1943 6 Sheets-Sheet 2 Aug. 14, 1945.

MANUFACTURE OF PIEZO uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu Aug, l4, 1945. M. RAMSAY 2,382,257

MANUFACTURE OFPIEZO-ELECTRIC OSCILLATOR BLANKS Filed April 21, 1943 6 Sheets-Sheet 3 INVENTOR flkwcu: AA WH 4 Aug. 14, 1945. M. RAMSAY 2,382,257

MANUFACTURE OF PIEZO-ELECTRIC OSCILLATOR BLANKS Filed April 21 1943 6 Sheets-Sheet 4 n \NVENTOR ffA/m J 16/4/ 714 )4 l 1 ATT I LJEY Aug. 14, 1945. A Y 2,382,257

MANUFACTURE OF PIEZO-ELECTRIC OSCILLATOR BLANKS Filed April 21, 1943 6 Sheets-Sheet 5 aiul lg A INVENTOR #46605 RAMJAK gig ATT RNEY mechanical (Y) axes of crystal.

Patented Aug. 14, 1945 MANUFACTURE OF rmzounaorarc OSCILLATOR BLANKS Marcus Ramsay, Great Neck, N. Y., assignor of eighteenand'three-fourths per cent to Albert Ramsay, eighteen and three-fourths per cent to Eric G. Ramsay, twenty-five per cent to H. Dorsey Spencer, all of New York, N. Y., and

- eighteen and three-fourths Young, Eugene, Oreg.

Application April 21,'1943, S eralNo. 483,906

(01. SIT-3) I 13 Claims. This invention relates to the cutting from bars,

sections, lumps or boulders of quartz, or other suitable crystals of accurately oriented blanks for use in the manufacture of oscillators or-res'i onators, such, for example, as those which are used in radio transmission apparatus. Although the invention is applicable to the cutting of blanks from other crystals which exhibit the phenomenon of piezo-electricity, for convenience it will be hereinafter described in its application to quartz since quartz is the material most commonly used for piezo-electric oscillators or resonators. As is well known, the frequency characteristics of quartz oscillators or resonators, such as those used in metering the wave bands of radio transmission sets, are dependent to a large extent upon the position of the quartz plate in the original quartz crystal. In order that the resonator or oscillator may effect uniform con-- trol of the wave band of a radio transmitter under various climatic conditions and, particularly, in order that its frequency may not vary too much over a comparatively wide range of temperatures, it is important that the blank from which the resonator or oscillator is made be so cut that its faces bear certain definite angular relations to the optical (Z), electrical (X) and the original quartz Cutting of such blanks from bars, sections, lumps or boulders'of quartz, as heretofore practiced, has resulted in considerable waste of material because the cutting methods and the apparatus employed have not permitted the maintenance of the orientation throughout the cutting operations. Not only has there been much waste of the raw material, but there has also been an even greater waste of time and labor in checking and correcting the errors in orientation brought about by the crude cutting methods and equally crude cutting apparatus heretofore employed. This has not been so important in the past, since supplies of crude material have been adequate to meet the heretofore existing demand. However, because of the now more extensive use of quartz oscillators and resonators, particularly in the radio transmission field, sup: j plies of quartz suitable for the making of such oscillators or resonators have diminished, the cost of the raw material has markedly increased, and it is therefore important, both for economy of material and economy of time and labor, to in-- sure as accurate an orientation as possible of 'tals-sometimes called boulders.

per cent to W. Ford each blank produced at the time the bar or boulder;

A general object of the present invention, therefore, is to provide improved methods and improved means for insuring the maintenance of the original orientation of the quartz, from which oscillator or resonator blanks are to be cut, throughout the successive-cutting operations required to produce the blanks, particularly when it is cut from proceeding by the more usual method of first cutting the lump or boulder into sections, then cutting the sections into bars and then cutting the blanks from the bars, the invention aiming likewise to insure the maintenance of the orientation when wafers of blank thickness dimensions are cut directly from the original lumps or boulvders. In the co-pending application of W. Ford.

Young, Serial No. 479,609, filed March 18, 1943, has been disclosed an improved process and apparatus for quickly and accurately orienting quartz or other crystals, either face or rough, that is, quartz or other crystal which either has some of its original crystal faces or which is in the form of broken or eroded fragments of crys-. The apparatus employed in practicing the said Young process preferably comprises a universal holder of such strength and rigidity and so mounted upon a removable slide or carrier that it can be transferred from the orienting apparatus to a cutting machine and serve as a jig or work holder for holding the work in proper cutting relation to the saw. However, the saws used in cutting either sections or wafers from rough lumps or boulders of quartz or from face crystals are usually metal disks havingtheir peripheral edges and margins impregnated with small diamond particles of sizes ranging from what may properly be called diamond dust up to 40 mesh or less. .In order thattoo much of the quartz may not be wasted in the kerf made by the saw, the cutting edges of these saws are relatively thin, for example in the neighborhood of ,4 thick, the disk being usually slightly thinner to provide some clearance or set for the saw. Even quartz cutting saws in which the diamonds are embedded in a disk produced by powder metallurgy have more or less the same characteristics,

a sufi'icient diameter to handle a fair-sized lump or boulder, is operating at its rated cutting speed there will be some slight tendency for the saw not to cut in an absolute plane but tolead off in one direction or the other and thus leave both the face of the blank severed from the bar or boulder and the face of the bar or boulder itself in planes slightly inclined to the desired planes for said faces. Although such deviations of the cuts from the desired planes do not tend to become cumulative, if the work holder be sufficiently rigid and the initial orientation be sufficiently accurate, it will be seen that if nothing is done to correct the error thus produced both faces of each blank will be inclined to the desired planes of such faces and both will have to be corrected. In order to do this it will be necessary to orient each blank'again. Such orientation may have to be effected several times while correcting the blank, provided the first correction made upon one of the faces does not completely restore it to the desired plane. Of course, when one face has been properly corrected, then the other face may be corrected with reference to that by bringing it into parallelism thereto. Such corrections, however, require not only considerable time and labor but also considerable skill.

An important object of the present invention is to provide a process and means for practicing the process of cutting the blanks which will obviate entirely any necessity for subsequent orientation of any except possibly the initial blank cut from a bar. To this end the present invention contemplates so effecting the cutting operations that each blank as it is severed from the bar or boulder will have one true face, that is, a face lying absolutely in the desired plane or, in other words, lying in a plane making the desired angle to the optical (Z) axis and having the other axes to be considered, that is, an electrical (X) axis and a mechanical (Y) axis also in the desired relations to said true face.

An important feature of the invention is the restoration to the bar or boulder, after each cut, of a face,to form one face of the succeeding blank or wafer, which lies in the desired plane of inclination and relation to the aforementioned various axes of the bar or boulder.

A further important feature of the invention is a novel combined saw and surface grinder in which these parts are so concentrically arranged and mounted that, after the bar, section, or boulder has been cut, the face of the bar, section or boulder from which the blank, wafer, bar or section has been cut will, in its further travel, pass over the concentric surface grinder mounted on the same shaft or spindle. In this manner extensive travel of the work holder in respect to the cutting and surfacing tools is eliminated and difficulty in maintaining them in their proper alignment in substantially the same plane is avoided.

Another important feature of the invention is the provision of means associated with a work holder in the blank cutting machine for effecting quickly and accurately such slight adjustment of this holder as may be necessary to compensate for any error growing out of transfer of the oriented bar to the holder, thus permitting such an adjustment, after the checking of an initial blank cut from a bar, as will insure that all subsequent blanks are positively oriented.

The invention also contemplates the provision of means for quickly and accurately bringing into operative position the abrading surface of the surface grinder when wear has so reduced said surface that it does not project sufficiently beyond the plane of the saw to perform efficiently its function of bringing the surface of the quartz from which the blank, wafer, bar or section has been out into the desired plane.

Other objects and important features of the invention will appear when the following description and claims are considered in connection with the accompanying drawings, in which- Figure 1 is a front elevation of a machine embodying-the apparatus features of the present invention and designed particularly for effecting the initial cutting of the oriented quartz or other crystal into sections, this machine being also adaptable to the cutting of the oriented quartz or other crystal into wafers if the latter method of preparing resonator or oscillator blanks is to be practiced. In the machine illustrated in Figure 1, the cutting saw and surface grinder are shown as mounted on separate shafts;

Figure 2 is a sectional plan view taken on the line 2-2 of Figure l;

Figure 3 is a plan view with the saw mounting shown in section of another cutting machine designed particularly for cutting the sections into bars from which the final blanks are to be cut;

Figure 4 is a front elevation of the mechanism shown in Figure 3;

Figure 5 is a section on the line 5-5 of Figure 4 and shows the cutter and surface grinder assembly where these two elements are combined in a single unit and are relatively adjustable;

Figure 6 is a sectional detail on the line 6-6 of Figure 3 showing the manner of clamping the work in the work holder employed in cutting the sections into bars;

Figure 7 is a perspective view of one of the bars after it has been cut from the section, the location of the optical (Z) axis, the electrical (X) axis, and the mechanical (Y) axis of the crystal being also indicated on this view;

Figure 8 is a front elevation of a machine designedparticularly for cutting the bars into oscillator blanks;

Figure 9 is a sectional plan on the line 9-9 of Figure 8;

Figure 10 is a plan view of the work holder employed in the machine shown in Figure 8, parts of the cutting mechanism being shown in section;

Figure 11 is a side elevation of the work holder shown in Figure 10 with parts of the cutting mechanism shown in section;

Figure 11A is a perspective view of an oscillator blank;

Fig. 12 is a plan view, partly in section, of a machine designed particularly for grinding a true face parallel to a finished true face such as provided by the preceding cutting machines, and particularlyfor providing the oscillator or resonator blanks with two true faces. This machine can also be used for grinding true faces parallel to existing true faces on other quartz pieces such, for example, as sections, bars or wafers, and also for making corrections where checking has shown accidental deviation;

Figure 13 is a side elevation of the machine shown in Figure 12;

Figure 14 is a section on the line l4l4 of Figure 15 through the work holding mechanism of the machine shown in Figures 12 and 13;

8 that do not lie in a true plane, that is, in a plane absolutely perpendicular to the optical (Z) axis of the quartz.

As more fully disclosed in said co-pending application of W. Ford Young hereinabove identified, the universal holder 2 is constructed not only to have its parts locked in the adjusted relations in which the final orientation of the tel to be oriented is preferably of such substantial construction that the relatively moving parts thereof may be locked in the relation in which they stand when the quartz or other crystal has been oriented and that, when thus locked, the

holder will hold the quartz with sufficient rigidity so that it may be fed to the cutting saw and surface grinder without losing its orientation. A

suitable universal holder for this purpose isonesuch as more fully shownand described in the co-pendin'g application of W. Ford Young, Serial No. 479,609; The universal holder of said co- .pending application comprises three nested rings,

the innermost ring turning about a diametrical axis on trunnions which have their hearing in the intermediate ring, the intermediate ring turning about a diametrical axis perpendicular to the inner ring axis and on trunnions having their bearings in the utermost ring and the outermost ring being arranged to turn about an axis perpendicular to the plane of the ring and also perpendicular to the axis about which the intermediate ring turns.

When orienting the crystal in suitable orienting apparatus, such as that more fully described in said c'o-pending application of W. Ford Young hereinabove identified, the aforementioned three rings are adjusted about their axes until the optical (Z) axis of the crystal has been definitely located, the crystal being fixedly held in the innermost ring. If the lump or block of quartz is to be first cut into sections, as shown in Figures 1 and 2, and then into bars from which the ulti-- mate oscillator or resonator blanks are to be cut, the orienting is so carried out that the universal holder 2 will present the lump or block 4 of the quartz to the section cutting saw 6 of the machine shown in Figures 1 and 2 with the optical (Z) axis of the lump 4 perpendicular to the plane of the out. From this it will be seen that when the saw 6 has made its out, both the cut surface on the lump 4 and that on any section 8 should lie in a plane substantially perpendicular to the optical (Z) axis of the quartz, in which case both the electrical (X) axes of the quartz and the mechanical (Y) axes of the quartz would lie in this face. In practice, however, it is substantially impossible to cause a saw 6, usually of the type which has its peripheral edge and margins impregnated with diamonds, to maintain its perpendicularity to the optical (Z) axis of the quartz throughout any substantial depth of cut.

This is largely due to the fact that, in order to avoid waste of the expensive and comparatively rare quartz which is suitable for resonators, the saw disk is made of relatively thin sheet metal so that the cutting edge, even allowing for some clearance or set, is usually not over f An important feature of the present invention, as hereinabove pointed out, is to compensate for this tendency of the cutting saw 6 to lead off and thus leave both a face on the quartz block 4 and a, corresponding face on the cut-off section quartz and the determination of the direction of the optical axis has been brought about, but this holder is also mounted upon a slide member I 0 having a dovetail slideway adapted to fit accurately upon a carefully machined dovetail guide that will position the holder definitely and accurately both in the orienting apparatus and in the section or wafer cutting machine. As herein shown, the dovetail guide l2 of the cutting machine is in turn formed upon a'second slide l4 travelling on a second dovetail guide IS on which the universal holder may be fed bodily in a direction transverse to the saw 6 to provide 'for cutting sections of predetermined thickness.

' As herein shown, the mechanism for effecting such transverse feeding of the lump or block 4 may be the ordinary transverse work feed mechanism for feeding work transversely to a. cutting tool, the illustrated mechanism comprising a screw I8 arranged to turn in bearings 20 in the work carriage 22, this screw being threaded through a lug 24 depending from the slide l4 so that turning of the screw will effect movement of the slide I4 transverse to the saw 6.

The carriage 22 itself has threaded therethrough a feed screw 26 arranged to turn in 5

bearings

28 and 30 in the frame of the cutting in the cut face of the. lump or block 4 that may machine and to be turned through suitable speed changing gearing in the housing 32, this gearing being driven from an electric motor 34.

By suitable manipulation of the cross feeding mechanism as, for example, by the handle 36, the holder 2, together with the lump or block 4 fixed therein, can be fed across its longitudinal path of travel with respect to the saw 6 to provide for cutting a section of the desired thickness from the quartz block 4. Feed of the block or lump 4 to the saw in the cutting operation is effected, of course, by the longitudinal feed screw 26 which may be turned at the desired rate of speed to secure the best cutting results. As is usual in feed mechanisms of lathes and milling machines, there is provision in the gear box 32 for various rates of feed.

As hereinabove suggested, one of the most important features of the present invention is the provision for insuring at least one accurately oriented face on each section, bar, blank or wafer out. As shown in Figures 1 and 2, the face of the lump or block of quartz 4, after a section 8 has been cut therefrom, is passed over a surface grinding wheel 38 which has its abrasive face lying in a plane exactly parallel to the normal plane of the saw 6 when idling or, in other words, the plane of the abrasive face of the surface grinder 38 is exactly-perpendicular to the optical (Z) axis of the lump or block 4 as the block is presented to the machine when it is to be cut intosections preparatory to cutting the sections into bars and then cutting the bars into blanks.

In the illustrative embodiment of the invention, shown in Figures 1 and 2, the surface grinder 38 is located at the right of the cutting saw 6 with its abrasive surface projected sufiiciently in front of the plane of the cutting'edge of the saw 6 so that it will engage and remove any irregularities have been left by the saw. Although separate driving motors l8 and 42 are shown, which are connected by V belts l4 and 46 to the shafts on which respectively the saw 8 and surface grinder -88 are mounted, it will be understood that separate drives are not necessary for these two tools and that they might be driven in any suitable manner from a single drive.

As brought out more fully in the co-pending application of W. Ford Young, hereinabove identified, when orienting the crystal 4 by means of the orienting apparatus and the universal holder 2, it is preferable, if the crystal is first to be cut into sections, then into bars, then into blanks, to orient it so that not only does the optical (Z) axis have a definite angular relation to the plane of the cut to be made in the crystal but also one of the other axes, for example, a mechanical (Y) axis, is brought into a definite relation to the path of travel of the crystal during the cutting and re-surfacing operations. An advantage of this is that it facilitates scratching a reference mark upon the re-surfaced face of the lump or block 4, after the cutting and surface grinding opera-- when it is being cut into sections, it will be seen' that the electrical (X) axis which is perpendicular to the thus located mechanical (Y) axis can readily be located. As shown in Figures 1 and 2, a convenient method of doing this is to hinge an ordinary steel square 48 upon the bed 58 of the machine in such manner that one leg of the square is parallel to the direction of movement of the carriage 22. with this arrangement, if the face of the block or lump 4 of quartz or other crystal be brought into a position, after it has been passed over the surface grinder 88, where it can be engaged by the vertical leg of the square 48, then a scratch mark placed upon this face, by using this vertical leg as a guide for the scriber, will correspond with an electrical (X) axis.

As shown in Figures 3, 5 and 7, one advantage in scratching the electrical (X) axis on the finished or true face of the section 8 cut in the machine shown in Figures 1 and 2 is that this scratch mark on the finished or true face, that is, the face that is absolutely perpendicular to the optical (Z) axis, can be used in locating the section 8 upon the glass plate 54 in such a definitely oriented position that when this glass plate 54 is clamped in the work holder 58 the section will be presented to the cutting saw 58, of the machine particularly shown in Figures 3 and 4, with the electrical (X) axis of the section 8 perpendicular to the plane of the cutting edge of the saw 58 and with its mechanical'(Y) axis parallel to the plane of the cutting edge of the saw 58 and its optical (Z) axis, of course, perpendicular to the bottom or finished face of the section 8. It will thus be seen that in the section 8 shown in Figure 3, the electrical (X) axis and the mechanical (Y) axis determine a plane coinciding with the finished bottom face of the section 8 and that the optical (Z) axis is perpendicular to this plane.

As shown in Figure 7, the bar 68, which is cut from the section 8 will also have a finished side face, as more fully hereinafter set forth, which is in a plane determined by the mechanical (Y) axis, originally located in the orienting apparatus, and the optical (Z) axis, also located in said orienting apparatus. The electrical (X) axis will extend transversely of the bar 68 in a direction parallel to the bottom or true face of the bar 88 and also in a direction which is perpendicular to the plane determined by the optical (Z) axis and the mechanical (Y) axis located in the original orienting operation.

An important feature of the machine shown in Figure 3, as well as an important feature of the present invention, is the combination with the cutting saw 58 used to cut the sections into bars of a concentric surface grinder 82 mounted upon thesame arbor or spindle 64 as the saw 58. It will be seen that the advantage of this arrangement is that, after the bar of quartz 68 has been cut from the section 8, the edge face of the section from which the bar 88 has been out can immediately be passed over the surface grinder 62 at the center of the saw 58 and thus have its face brought into a true plane perpendicular to the electrical (X) axis, in which plane both. the optical (Z) axis. and the mechanical (Y) axis, located by the orienting step, will lie. As shown, the abrading face of the surface grinder 62pmjects slightly from the plane of the front face of the saw 58 so that, without changing the transverse adjustment of the section 8 in respect to the saw 58, the surface grinder 82 can remove any irregularities on the edge face of the section 8, from which a bar 88 has been cut, that may have been left by the saw.

In order that the aforementioned relationship between the abrading surface of the surface grinder 82 and the plane of cut of the saw 58 can be maintained throughout the life of the surface grinder or, in other words, that compensation may be madefor wear, provision is made for quickly, easily and accurately effecting such an adjustment of the surface grinder 82 with respect to the saw 58 as will compensate for any wearing down of the abrading surface of the surface grinder 62. As shown particularly in Figure 5 of the drawings, the arbor or mandrel 84 of the saw 58 has keyed thereto the threaded hub 68 of a member provided with a cylindrical socket 88 in which the surface grinder 82 is mounted and in which it may be secured in any suitable manner as, for example, by means of cement 18. The hub 66 can be secured upon the arbor or mandrel 64 by means of a nut 12 engaging a washer 14 which in turn engages the bottom of the socket 88.

Threaded upon the hub 65 and adjustable thereon is a second hub 16 having a similar socket-like member 18 in which the socket 68 is received and to the margin of which the saw 58 is secured. The disk of the saw 58, it will be noted, has its center cut out to receive the socket 88. A lock nut 88 secures the two

hubs

66 and 16 in their adjusted relation to each other. Tightening of the lock nut 88 and turning of the hub 16, to effect the relative adjustment of the abrading surface of the surface grinder 62 and the plane of the cutting edge of the saw 58, may be effected by suitable spanners received in

sockets

82 and 84, respectively in the hub 16 and in the lock nut 88.

As hereinabove pointed out, a scratch mark is preferably made upon the trued face of the section 8 before it is cut from the lump or block 8 plane which is perpendicular to the either toward arallelism to a of the quartz by the cutting machine shown in Figure 1, this scratch mark being made usually by guiding the scratching diamond along the edge of the vertical leg of the square 48 in Figure 1. This scratch mark is then used to locate or orient the section 8 upon a glass plate 86. The section 8 is cemented to the plate 86 after it has thus been accurately oriented.

The purpose of the glass plate 86 is twofold: (a) it provides means by which the section 8 to be cut into bars 68 can be secured rigidly in the work holder in proper oriented relation to the saw; (17) it prevents chipping of at least one edge of the quartz during the bar-cutting operation and also prevents prematur breaking off of the bar from the section; the glass plate usually extending to some distance to each side of the section 8.

From theforegoing it will be seen that, if the edge of the glass plate 86, which is usually bevelled to fit into a dovetailclamping groove 88 in" the work clamping part of the work holder 88, be used as a reference mark in orienting the quartz section 8- in the holder 88, the dovetail groove 88 being held accurately in a horizontal vertical lane of the cutting edge of the saw 58 and having its side recess, which receives the bevelled edge of the glass 86, also perpendicular to the plane of the cutting saw 58, then both the true face of the section 8, that is, its bottom face which lies against the glass plate 86, and the electrical (X) axis, which has been scratched upon the true face of the section 8, can be definitely and accurately oriented in respect to the saw 58. This can be done merely by mounting the section 8 upon the glass plate 86 with its true face against the upper face of the glass 86 and the scratch mark, showing the direction of the electrical (X) axis, parallelito the bevelled edge of the lass plate.

hereinabove suggested, it is also customary, andjit, is likewise important that the direction on the bar'68 in which an original major or minor apex face of the crystal was located be indicated. This maybe done, as above suggested, by marking on the section 8 an arrow 82 pointing in the direction of the apex face to be considered, here a minor face. As is well known, blanks for resonators or oscillators which are to have substantially a zero temperature coefilcient are usually cut at an angle to the optical (Z) axis which causes them to be inclined to the said optical (Z) axis major apex face or toward parallelism to a minor apex face. Thus, if the direction of a major face be marked upon the section 8 and then appear also upon the bar 68, it facilitates properly in the machine in which it is to be cut into sections inclined to the optical axis, either for an AT or a BT cut.

As shown in Figures 4 and 6, one side of the dovetail groove 88 which receives the glass plate 86 comprises a movable member 84 which may be pressed into clamping relation to the bevelled edge of the glass plate 86 and thus force the other edge into accurately oriented relation to the fixed side of the groove 88. This may be done my means of a milled clamp nut 86 on a bolt 88 extending through the work holder 88, the nut 86 having a rounded inner end engaging the clamp member 84 and the rod 88 having a rounded head I88 engaging the end of the opening I82 through the holder 88 in order to provide the required freedom of adjustment positioning the bar 68 pointer I 24.

p 5 necessary to prevent breaking of the-edge of the glass plate 86 during the clamping operation.

The work holder 88, in which the glass plate 86 with the section 8 mounted thereon is clamped, is itself mounted on a carriage I84 movable parallel to the plane of the saw 58, the work holder 88 being movable on the carriage I 84 transversely to the plane of the saw and being accurately guided in its transverse movements by a dovetail I86 received in a similarly shaped guideway I88 in the carriage I84. The movement of the work holder 88 on the carriage I84 transverse to the plane of the saw 58, in order to feed a width of the section 8 into position to be cut into a bar 68, can be brought about in any suitable manner. As herein shown, this adjustment is usually effected by hand, a clamp screw II8 being arranged in accessible position to clamp the work holder 88 in its adjusted relation to the carriage I84. To facilitate the transverse adjustment, "so, that bars 68 of predetermined and uniform width may be out, a stop member II2, pivoted at I I4 to swing on the stem I I6 of a gage screw I I8, can be swung into. position so that the finished face of the section 8 will strike this stop, the setting for the desired width being predetermined in any suitable manner as, for example, by providing the milled head I28 of the gage screw with graduations I22'to be read in respect to a The section 8 having been cut into bars 68 in the manner hereinabove described, it will be seen that, by the procedure so far described, each of these bars 68 will be provided .with two ac-, curately oriented faces, one being its part of the original accurately oriented face of the section 8, this face of the bar 68 being the one next to the glass plate 86, and the other accurately oriented face being one of the side faces of the bar 68, namely, the one that has been ground upon the edge face of the section 8 from which the previous bar 68 has been cut, this grinding being done, as hereinabove pointed out, by passing the edge face of the section 8 over the surface grinder 62 after the saw 58 has cut ofi the previous bar 68. It will thus be seen that each bar 68 is provided with two very accurately oriented faces which may be used in mounting it inthe work holder of the machine in which the bar 68 is to be cut into blanks for oscillators or resonators.

If only one bar 68 is to be cut into blanks at a time it is usually not necessary to provide further accurately oriented faces on the bar 68 before mounting it upon the glass Plate I26 by means of which it can be held in the work holder and accurately oriented in respect to the cutting saw I28 and the surface grinder I88 of the blank cutting machine. Since, however, it is usually desirable to mount more than one bar 68 on the glass plate I26 of the blank cutting machine, so that two or more blanks may be cut at each cutting operation, it is sometimes desirable, in order to facilitate the orienting of the two bars in respect to the glass plate I26 and in respect to each other, to provide at least one of the bars with two accurately oriented side faces. This can readily be done, as will appear more fully hereinafter, by the use of the machine shown in Figures 12 and 13. As more fully described hereinafter, in this machine a face parallel to 7 any true face may be ground upon a section, bar

or blank by mounting the true face against the made.

work-locating face of the work holder of the machine and then passing the other face over a surface grinder which has its abrasive surface in a plane parallel to the work-locating face of the work holder.

If, as shown in Figure 9, it is desired to out two blanks at each cutting operation of the blank-cutting machine, then it is usually preferable to grind another true side face on one at least of the bars 60 which'is parallel to the true side face provided on said bar as amincident to the bar-cutting operation. The two bars may then be mounted on the glass plate I26 with a lateral true face of the one bar against a lateral true face of the adjacent bar and with both of the top arrows 92, indicating the direction of a minor apex face, pointing in the same direction, this direction varying according to the cut to be As hereinabove pointed out, however, blanks for resonators or oscillators that have a substantial zero temperature coefiicient are usually cut at an angle to the optical axis, one of the most common types of blanks showing such zero temperature coefficient characteristic being made by the so-called BT cut and the angle of this cut usually being in the neighborhood of 49 to the optical axis.

The work holder for the blank cutting machine comprises, in the illustrative embodiment, a casting I32 having a machined face I34 inclined to the plane of the saw I28 and also to the plane of the surface grinder I30 substantially at the desired angle of the cut to be made. Since, in the bars 60, the optical (Z) axis is perpendicular to the bottom true face of the bar, this gives the desired inclination of the face of the oscillator blank to the optical axis. As hereinabove pointed out, the mechanical (Y) axis of the crystal extends lengthwise of the bar 60 and the electrical (X) axis extends transversely to the length of the bar or, in other words, it extends parallel to the plane of the saw I28 when the bar is in the position shown in Figures and 11.

To permit such slight adjustments as may be necessary to correct any deviation from the original accurate orientation which may havebeen brought about either in the intermediate bar cutting operation or in the mounting of the bar 60 on the glass plate I26, the work holder I32 is pivoted at I36 upon a support I38 so that its inclination to the plane of the saw I28 may be varied slightly. To permit quick adjustment of the inclination of the work holder I32, a cam shaft I40 has its bearings in the support I36 and engages the under side I42 of the holder I32 to increase of decrease the inclination of the holder I32 to the plane of the saw I28 as the cam I40 turns. A strong spring I44 connected at I46 to the base of the support I38 and connected at I48 to the under side'of the holder I32 tends to hold the holder I32 tightly against the cam shaft I40.

After the first oscillator blank is cut from the bar or bars 60 in the manner shown in Figures 10 and 11, it is checked in any suitable goniometer to determine whether or not the inclination of its true face to the optical axis is correct and also to determine whether or not the electrical or (X) axis is also properly directed. In other words, the blank is checked for what are commonly referred to as the A and "B angles, the A angle being the angle between the (X) axis of the mother crystal and the intersection of the crystal face and the XY plane, and the B angle being the angle which the crystal face makes with the XZ plane.

The adjustment just described is for the purpose of compensating for any variation of the cut from the desired B angle. To facilitate this adjustment a scale I50, concentric with the axis of the cam shaft I40, is graduated in minutes and a pointer I52, connected to the cam shaft and moving over the scale, permits the operator to determine at once, after the variation from the desired B angle has been ascertained, how much of an adjustment is necessary to correct this variation.

It will also sometimes happen, in mounting the bars 60 on the glass plate I26, that there is an accidental deviation from the desired A angle. This angle can alsobe checked in the goniometer readings from the first blank cut from am! bar 60 and adjustment be made to compensate for any variation from the desired A" angle.

The illustrated means for compensating for any variation from the A" angle which may be found when the first blank cut is checked in the goniometer, comprises a normally fixed guide bar I54 for the glass plate I26, said bar I54 being pivoted at I56 on the upper face I34 of the holder I32. The bar I54 is secured to the face I34 by machine screws I58, the stems of which extend through arcuate slots I60 so that the bar I54 may be rocked about its pivot I56 to a limited extent to permit such swinging of the crystal bars 60 in the plane of the upper face I34 of the work holder asmay be necessary to compensate for any variation from the desired A angle that may have been found when checking the first blank cut. In order that this adjustment also may be made directly without any trial and error procedure, an adjusting screw I62 is threaded through a lug I64 near the upper end of the bar I54. The screw I62, having its bearings in the member I66, serves to cause the bar I54 to swing in either direction about its pivot I56 when the clamp screws I58 have first been loosened. A pointer I68, cooperating with the peripheral scale I10 on the head I12 of the screw I62, permits the operator to read directly the amount of compensating adjustment necessary to correct any deviation from the desired A" angle which may be found in checking the first blank cut.

From the foregoing it will be seen that provision is made for quickly insuring the proper positioning of the bars 60 in respect to the saw I28 in the blank cutting machine of the present invention in the event that slight deviations from the desired A and BT angles have come about either through mounting or otherwise. It may be said, however, that ordinarily, substantially no adjustment isrequired and that, even if adjustment be required, the first blank cut can usually be corrected in the machine hereinafter to be described so that it will be usable. Furthermore, ordinarily after checking the first blank and making the required adjustments, it will be found that the second blank out has both its A and B angles practically on the nose and therefore no further checking is necessary. This greatly facilitates the production of blanks since, in this machine as in the operation of the machines shown in Figures 1, 2 and in Figures 3 and 4, after each blank H3 is cut from the bar 60 the bar is provided with a true or properly oriented face by passing it over the surface grinder I30. Therefore, each blank II3 cut from the bar 60 has one accurately oriented face which can be used in the machine now to be described for providing the blank with another accurately oriented face.

The feedin of the bars 60 to the cutter I28 may be effected in any suitable manner as, for example, by the usual milling machine feed screw I14 and the feeding of the bars 60 transversely to the cutter I28, to cut blanks I13 of the desired thickness, is preferably done by hand. To facilitate insuring uniform thickness, a stop I 16 is provided which comprises a machine screw threaded through the frame I18 of the cutting machine and so positioned at one side of the saw, as shown in Figure 9, that the resurfaced ends of the bar 60 may be brought into abutting relation to this screw and then clamped in this relation to insure the cutting of blanks I13 of the desired thickness and orientation; To facilitate such adjustment, the head I80 of the screw I16 is provided with thickness graduations I82 which may be read in respect to a pointer I84.

To permit the resurfaced ends of the bars 60 to be brought into abutting relation to the screw I16, the glass plate I26, on which the bars 60 are mounted, may be unclamped so that it can slide along the fixed guide I54 which, after any required adjustment to compensate for variation from the desired A angle, has been locked in this adjustment by the set screws I58. The guide bar I54 has an overhanging bevel which engages the bevelled side of the glass plate I26.

Another movable guide and clamping bar I86 with a similar overhangin bevel, engages the other bevelled edge of the glass plate I26. The

guide bar I86 is movable on guide pins I88 into and out of clamping relation to the glass plate I26.

vA clamping bolt I90, having arounded head fittedinto a rounded socket in the clamping bar I86, is provided at the other side of the frame with a wing nut I92 by which the bar I86 can quickly be brought into clamping relation to the glass plate I26 and as quickly released. By unscrewing the nut I92 the glass plate I26 may be permitted to slide down into abutting relation to the stop I16 and then secured in this relation, thus insurin the cutting of blanks of substantially uniform thickness.

In each of the machines thus far described which have provision for grinding a true face,

on the section, bar or blank before it is cut from the lump, section or bar it will be obvious that the relative movement of the work to be ground and the grinder need not be at the same rate of speed as the relative movement of the work to be cut and the saw. To avoid any delay in production it is therefore sometimes advantageous either to provide for a change of speed in the feeding mechanism when the Work is being passed over the surface grinder or to disconnect the mechanical feed and effect the surface grindin feed by hand. i

From the foregoing description it will be seen that, in each step of the process so far described the section, bar or blank, cut respectively from the lump, section or bar of quartz or other crystal, is provided with at least one accurately oriented face before it is cut from the bar. This may not, of course, necessarily be true of the first blank cut, as above explained, because of accidents or carelessness in mounting on the glass plate I26, but even such blanks, after checking, can readily have true faces restored in the machine presently to be described. However, if the section, bar or blank has one true face it is a simple matter to provide it with another true 'face. This may be done in the machine just referred to which'is shown in Figures 12 to 17 inclusive.

In the machine shown in Figures 12 to 17 inclusive, a wheel I94 mounted on a rotatable shaft I96, having its lower bearing in the main frame I98 of the machine and its upper bearing in the gooseneck 200, carries a plurality of work holders 202 which carry the work in a horizontal plane '(ver the face of a surface grinder 204 driven by a suitable motor 206. The rotation of the wheel I94 to effect the movement of any work holder 202 in the direction to carry its work over the abrasive face of the surface grinder 204 is preferably effected by hand and may comprise an oscillating movement to carry the work over the grinder first in one direction and then in the other direction.

To hold the work, such as a blank, bar or section, upon the work holder, in order to effect the grinding of a face on the work parallel to an accurately oriented face, suction means are provided. As herein shown, particularly in Figures 14 and 17, each work holder 202 has an under face 208 which, in its normal adjustment, lies in a plane exactly parallel to the abrasive surface ofthe surface grinder 204. Also, as herein shown, each holder 202 has, opening through this face 208, three suction openings 2I0, 2I2 and 2I4, communicating with any suitable vacuum pump, such communication being preferably made by means of flexible vacuum hose 2I6 to permit free oscillation or turning of the wheel I94;

In the form of the work holder shown in Figure l4, vacuum for the suction opening 2I0 is provided through a connecting pipe 2I8 controlled by hand valve 220. Similarly vacuum for the suction opening 2I2 is provided through a branch pipe 222 controlled by a valve 224 and vacuum for the suction opening 2I4is provided through a branch pipe 226 controlled by valve 228.

As above suggested, when the work holder 202 is in its normal adjustment the under face 208 thereof is absolutely parallel to the surface grinder 204 so that, if a blank I13, for example, which is to be provided with a second true face, has one true face, then by simply putting that true face against the surface 208 the operator can be assured of having another true face ground upon the side of the blank adjacent to the surface grinder 204, when the face 208 of the holder 202 is in its normal position of adjustment in which it is parallel to the plane of the abrasive surface of the grinder 204.

When, however, it is desired to use the machine illustrated in Figures 1'2 .to 17 for correcting the initial check blanks, it is desirable to make provision for inclining the face 208 in respect to the plane of the abrasive surface of the surface grinder 204 in order to provide for any variation which the resurfaced face of the check blank may show from the desired A and/or B angles. In the illustrative embodiment of the invention, the main body 232 of the work carrier, which may be fastened upon the rim of the wheel I94 as shown in Figure 15 by any suitable means such as a clamp screw 234 and through bolts 236, is provided with a guideway 238 in which the work 'quired to hold the work inplace.

through which an adjusting screw 244 is threaded, this screw being mounted in a bearing 246 on the carrier frame 232 and having a graduated head 248, the 'work thickness graduations of which may be read in reference to a pointer 2 0.

Fulcrumed upon a pivot 252 screwed into the vertical slide 240 is the work holder proper 202, in the bottom face 208 of which the suction openings 2l0, 2I2 and 214 are provided. In order to effect angular adjustment of the work, holder 202 about the pivot 252, the upwardly extending arm254 of this work holder is provided with a swivel 256, having its bearing in the upper end of said arm and through the squared head of which is threaded an adjusting screw 258 having a bearing in the slide 240 and having a graduated head 260, the angle graduations of which can be read in reference to a pointer 262.

From the foregoing description it will be seen that by vertical adjustment of the slide 240, the.

thickness to which it may be desired to reduce any section, bar or blank when grinding a second true face parallel to the original true face, can readily be predetermined. It will further be seen that by the angular adjustment of the work holder 202 the work positioned against the face 208 can be tilted to such an angle to the plane of the surface grinder 204 that correction of any variation from the A or B" angles which may be found, for example, in the check blank first cut from a bar in the machine shown in Figures 8 to 11 inclusive, may readily be corrected.

In Figure 17 is shown modified valve-controlling means for controlling the application of the suction to the respective suction openings H0, H2 and 2| 4. It will be apparent that, when finishing blanks, that is, providing each blank with a second true face parallel to the first, these blanks having relatively small face areas, for

example, x or 74" x 3.4", only one suction opening will be required to hold the work in place. For larger pieces of work, such as bars and sections, suction applied to the work from either two or three of the openings may be re- In the form of the work holder shown in Figure 17, instead of using separate valve controls 220, 224 and 228, as shown in Figure 14, the valves 264, 266 and 268 are in the form of sliding cylinders of different widths mounted on a common shaft 210 sliding through a stuffing box 212. On the shaft 210 is an operating handle 214. An indicator 216, pivoted at 218, and having a pointer passing over a chart 280 is moved by the handle 214 to indicate on the chart both the off position in which all three suction openings are closed and the positions in which either one, two or three of the I suction openings 2I0, 2I2 2|4, are in working condition.

From the now completed description of the novel procedure of the present invention which is carried out in the manufacture of resonator or oscillator blanks that have their faces and edges properly oriented, it will be seen that, from the time the initial orientation has been effected, throughout each Succeeding cutting operation there is very little opportunity for the orientation to be lost. This has been effectively demonstrated in the manufacture of thousands'of accurately oriented blanks. It will further be ,seen that substantially the only steps in the manufacture of the resonator or oscillator blank which require any special skills are the original orientation, the preferredinethod of which, more fully disclosed in the co-pending application of W. Ford Young, Serial No. 479,509, filed March 18, 1943, is not in itself a part of'the present invention, and in the checking of the A and B" angles of the first oscillator blank cut from the bars 60 in the machine shown in Figures 8 to 11, inclusive, to be sure that the original orientation has notbeen disturbed in the mounting of the bars 60 on the glass plate I26. Except for these two steps, which require some knowledge of the relationship of the faces of the oscillator blank to the original axes of the mother crystal, all other operations can be performed by comparatively unskilled labor.

With such unskilled labor, supervised only as to the orientation and checking, oscillator blanks can be cut on a large scale production basis with a minimum waste of the quartz, which blanks can consistently be kept within 5 minutes of either the A angle or the 3" angle, which is well within the tolerances allowed for blanks that are to be finished into piezo-electric oscillators having definite frequencies and substantially zero temperature characteristics.

What is claimed as new is:

1. The process of cutting quartz or other crystals which exhibit the phenomenon of piezo-electricity, in the manufacture of piezo-electric oscillators, which consists in so orienting a crystal block from which a section, bar, blank or wafer is to be cut and so fixing said block in parallel-feeding relation to the crystal-cutting saw that throughout the successive relative cutting movement of the block and saw required to cut a plurality of sections, bars, blanks or wafers from the block, the oriented axes of said block bear the desired predetermined angular relations to the plane in which the cutting edge of said saw travels when moving idly, effecting the relative cutting the'said block fixed in the same parallel feeding relation to said plane, passing the cut face of the block over an abrading tool which has its abrading face movable relatively to said block in a plane parallel to the aforementioned plane of idle movement of the cutting edge of said saw, in order to remove irregularities in said freshly cut face of said block which may have been caused by any deviations of said saw, during the cutting operation, from its aforementioned plane of idle movement, whereby at least one face of each succeeding section, bar, blank or wafer cut from the block will be in a true plane to which its axes will bear 4 the aforementioned predetermined angular relaions.

2. A process according to claim 1 in which the crystal block is quartz and is fixed in its parallelfeeding relation to the crystal-cutting saw with its optical (Z) axis perpendicular to the plane of idle movement of the cutting edge of said saw.

' 3. A process according to claim 1 in which the crystal block is quartz and is fixed in its parallelfeeding relation to the crystal-cutting saw with a mechanical (Y) axis parallel to the direction of the feeding movement thereof.

4. A process according to claim 1 in which the crystal block-is quartz and is fixed in its parallelfeeding relation to the crystal-cutting saw with with an electrical (X) axis perpendicular to the direction of the feeding movement thereof.

5. Apparatus for use in cutting sections, bars, blanks or wafers from a block of oriented crystal in the manufacture of piezo-electrlc oscillators which comprises a holder in which said crystal block may be fixed in the desired oriented relatlon to the plane of the idle movement of the cutting edge of the crystal-cutting saw, said holder having provision for adjustment of said block across the said saw plane withoutdisturbing its oriented relation thereto to permit cutting therefrom pieces of the desired thickness. and means for effecting a relative work feeding movement of said saw and said holder in directions parallel to said plane to eii'ect the cutting of said pieces from said block, and a surface grinder so located in an extension of the path of relative feeding travel of said block and said saw as to engage the face of the block from which a piece has been out. after the cutting operation has been completed, the abrading face of said surface grinder lying in a plane parallel to the plane of the idle movement or the cutting edge of said saw.

6. Apparatus according to claim in which the surface grinder is concentric with the saw and is mounted on the same shaft.

7. Apparatus according to claim 5 in which the surface grinder is concentric with the saw, is mounted on the same shaft and has its abrasive face in a plane slightly raised from the plane of,

the cutting edge of the saw.

8. Apparatus according to claim 5 in which the surface grinder is concentric with the saw. is mounted on the same shaft and has its I abrasive face in a plane slightly raised from the plane of the cutting edge of the saw and in which means are provided for effecting a relative adjustment of said saw and said surface grinder to compensate for any variation in said plane relations due to wear.

9. A combined saw and surface grinder for the A purposes described, comprising a circular saw and surface grinder concentrically arranged and interconnected, the abradingsurface of the surface grinder being raised slightly from the plane of the cutting edge of the saw and the combined structure having means for effecting a relative adjustment of the saw and surface grinder along the common axis thereof to compensate for wear of the abrading surface of the grinder.

10. Apparatus according to claim 5 in which the block holder comprises parts relatively adiustable to bring the crystal block held thereby into the desired oriented relation to the plane of the idle movement of the cutting edge of the crystal cutting saw and also comprises means for locking the relatively movable parts in this adjusted relation.

11. Apparatus according to claim 5 in which the work holder has a work supporting face normally inclined to the plane of the saw at the dement of the work in the plane of the inclined face of the said work'holder to compensate for errors in orientation in respect to the A" angle of the oscillator blank.

13. A combined saw and surface grinder for the purposes described comprising a circular saw and a circular surface grinder concentrically arranged and interconnected, said surface grinder comprising an abrasive surface and a circular support therefor of sufficient axial-thickness to form a solid, inflexible backing for said abrasive surface and alsoconstitute a supporting hub for the saw, and said circular saw comprisinga relatively thin, easily flexed, disk having a narrow cutting edge and being of sutliciently greater diameter than the circular surface grinder to permit complete severance of each piece to be cut successively from a block or the like before the cut face of the block comes into engagement with the surface grinder, said saw being so mounted on said relatively thick hub that the abrading surface of the surface grinder is raised slightly from the side of the plane of the cutting edge of the saw adiacent to the cut face of the block, whereby any deviation of the face of the block from said plane, resulting from wandering of the relatively thin, easily flexed saw, may be corrected by said inflexibly mounted surface grinder.

MARCUS RAMSAY.