Lapping Machine

Abstract

A lapping machine in which the horizontal rotating circular disk providing a lapping surface is maintained in a substantially flat or planar condition without the use of truing plates or rings normally used for such purpose. A combined workpiece holder and pressure plate is attached to the lower end of each of a plurality of rotatably driven spindles which are horizontally adjustably positioned along radial lines extending between the axis or centerline of rotation of the lapping surface and the outer periphery of such surface. The plurality of spindles and their respective workpiece holders and pressure plates are positioned along their respective radial lines so that the paths of rotation of workpieces disposed between the lapping surface and the lower surfaces of the combined holders and pressure plates extend about the axis of rotation of the lapping surface in different but somewhat radially overlapping circular paths. Each spindle is rotatably driven by a respectively associated variable speed motor so that the speed of rotation of each respective holder and pressure plate and the workpieces therebelow can be adjusted to compensate for the different rotational speeds of said circular paths extending about the axis of rotation of the lapping surface.

Description

BACKGROUND OF THE INVENTION

Lapping machines of heretofore known types require the use of truing rings or plates to maintain, in a planar condition, the lapping surface provided by a horizontal rotating circular disk in each such machine. As is well known such lapping surfaces are unevenly worn during lapping operations so that the lapping surfaces must be frequently dressed to return such surfaces to their flat or planar condition for optimum lapping of workpieces.

There is, for example, disclosed in U.S. Pat. No. 2,992,519, issued July 18, 1961 to C. J. Pearson, a polishing apparatus or lapping machine in conjunction with which there is employed a relative massive and heavy truing plate 39 which is used to maintain the surface, layer or face 16 of polishing disk 11 exactly true or flat. It will be noted that truing plate 39 has a diameter somewhat larger than the width of the annular upper lapping surface 16 of disk 11 and, therefore, plate 39 overhangs the inner and outer edges of such annular surface.

As another example, there is disclosed in U.S. Pat. No. 3,110,988, issued Nov. 19, 1963 to S. A. Boettcher, a lapping machine in which truing-retainer rings 46 are employed for maintaining the annular lapping surface 24 of lap wheel or plate 22 in a flat condition at the same time that lapping or polishing operations are being performed on workpieces such as W. The diameters of the truing-retainer rings such as 46 are also greater than the width of annular surface 24 of lap wheel 22 and, therefore, such rings also overhang the inner and outer edges of said annular surface. U.S. Pat. No. 3,304,662, issued Feb. 21, 1967 to S. A. Boettcher also shows, in FIGS. 1 and 2, the use of truing-retaining rings 30 which are similar to the rings 46 of the prior cited patent to Boettcher.

The truing plates or rings shown in the above cited patents must, of course, be replaced periodically because they are worn down along with the upper lapping surfaces of the lap disks. In addition, a truing plate as shown in the cited patent to Pearson is relatively difficult to handle and such plate occupies a station which could be used for an additional workpiece lapping station. These several factors add to the cost of lapping or polishing operations and, therefore, ways are continuously being sought to entirely eliminate the use of truing plates or rings, and/or to substantially reduce the frequency in which the lapping surfaces of lap disks must be dressed to return such surfaces to flat or planar surfaces. Accordingly, the lapping machine of the present invention was developed to attain such objects or ends.

SUMMARY OF THE INVENTION

In accomplishing the foregoing objects, there is provided a lapping machine employing an annular rotating lap or lapping disk similar to that employed in previous lapping machines but in which the workpiece holders, or combined workpiece holder and pressure plates or members, are attached to the lower ends of respectively associated and individually rotatably driven spindles which are horizontally movable along radial lines extending between the axis or center of rotation of the lapping disk or lap and the outer periphery of such lap or disk. Each spindle has associated therewith a spindle assembly or head which supports the respective spindle and includes a variable speed motor for rotatably driving the associated spindle at selected speeds. The spindles are horizontally movable or adjustable so they can be staggered across the width of the annular surface of the lap or lapping disk so that workpieces disposed between the bottoms of said combined workpiece holders and pressure plates are moved by rotation of said spindles through rotational paths which extend about the axis of rotation of the annular surface of said lap in different but radially overlapping circular paths. The speed of rotation of each spindle is selected in accordance with its path about said axis so that the speed of movement of each of the workpieces over the annular lap surface is substantially the same as that of all the other workpieces.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 comprises a top plan view of a lapping machine in accordance with the invention;

FIG. 2 is a front elevational view of the apparatus or machine of FIG. 1, such view being taken generally along line 2--2 of FIG. 1;

FIG. 3 is an enlarged elevational view of part of the apparatus of FIG. 1, such view being taken generally along line 3--3 of FIG. 1;

FIG. 4 is a top plan view of the apparatus of FIG. 3, such view being taken generally along line 4--4 of FIG. 3 with an upper part of the structure shown in FIG. 3 broken away to show details of structure below such upper part;

FIG. 5 comprises a top plan view of one form of a combined workpiece holder and pressure plate adapted for use with the apparatus of the present invention, such view being taken generally along line 5--5 of FIG. 3 and also illustrating a workpiece disposed against the lower surface of the workpiece holder and pressure plate;

FIG. 6 is an enlarged and detailed elevational view of a part of the apparatus of FIG. 4, such view being partially in cross-section and taken generally along line 6--6 of FIG. 4; and

FIG. 7 is an enlarged and detailed top view of the apparatus of FIG. 6, such view being partially in cross-section and taken generally along line 7--7 of FIG. 6.

Similar reference characters refer to similar parts in each of the figures of the drawings.

PREFERRED EMBODIMENT OF THE INVENTION

Referring to FIGS. 1 and 2 of the drawings in detail, there is generally shown a lapping machine 10 including an annular lapping or lap disk 11 of a usual type and having an upper, annular, horizontal and planar lapping surface 11a. Disk 11 is supported on the top of a table 12 which is, in turn, supported by a pedestal 13, such pedestal and, thereby, said table and said disk, being rotatable about a central axis by a variable speed motor means in any of the manners which are now old and well known in the art, such motor means being omitted from the drawings for purposes of simplification thereof.

A bridge member 16 including a plurality of laterally extending arms 17, 18, 19 and 20 spans said planar lapping surface 11a generally horizontal thereabove and is supported above such surface by a plurality of upright legs or support members such as 21 and 22. Inverted L-shaped spindle assembly support plates 17a, 18a, 19a and 20a (see FIG. 6) are secured to the bottoms of arms 17, 18, 19 and 20, respectively, in any convenient manner, such as by welding for example, and a spindle assembly is secured to the vertical face of each said support plate, the respective assemblies secured to support plates 17a, 18a, 19a and 20a being designated 23 through 26, respectively. Spindle assemblies 23 and 24 are identical in structure to each other while spindle assemblies 25 and 26 are also identical in structure to each other as well as being mirror images of assemblies 23 and 24. This will be readily apparent from a brief study of FIGS. 1 through 4 of the drawings and, therefore, it is expedient for purposes of brevity and necessary for an understanding of the invention to describe in detail the structure of only one of said spindle assemblies.

Referring further to FIGS. 1 and 2, taken in conjunction with FIGS. 3, 4, 6 and 7, spindle assembly 23 includes a stationary and horizontally extending track member 30 whose back is secured in any convenient manner, such as by welding, to the face of support plate 17a which is attached, as previously mentioned, to arm 17 of bridge member 16. The front of track member 30 is provided with horizontally extending and somewhat dovetail shaped projections or tenons which extend into similarly somewhat dovetail shaped and horizontally extending grooves or mortises provided in the back of the lower part of a vertically extending support member 31, such grooves and projections being complemental to each other with a snug but slidable relationship therebetween. Horizontal wear strips 35 and 36 of a hardened and polished material are disposed between members 30 and 31 and are secured to member 30 (See FIG. 6). The lower part of support member 31 is provided with a threaded hole 37 (FIG. 6) into which a first end of a cooperatively threaded shaft or rod 38 extends. This will best be understood from the corresponding arrangement for member 61 as shown in FIGS. 1, 2 and 3 of the drawings, and including threaded hole 67 and cooperatively threaded rod or shaft 68. The second end of shaft 38 extends through and is rotatable in a suitable bearing 39 secured in any convenient manner to the face of a bearing support block 40 which is, in turn, secured in any convenient manner to a first or outer end of horizontal track member 30 (FIG. 1). A manually actuable crank assembly 41 is mounted on shaft 38 at the extreme end of said second end thereof, and manual turning of the crank of the crank assembly 41 will impart corresponding rotation to shaft 38 and, thereby, move member 31 horizontally along horizontal track member 30 in a direction corresponding to the direction of said rotation of shaft 38 as will be readily apparent to those skilled in the art.

Spindle assembly 23 further includes a roller support member 32 which is secured, as by welding, to the front of the lower end of vertical member 31 as best shown in FIGS. 6 and 7. A first vertical row of three rollers such as 42 (FIGS. 6 and 7) are rotatably mounted on roller support member 32 adjacent a first or inner side thereof and a second vertical set of three rollers such as 43 are rotatably mounted on said roller support member adjacent the second or outer side thereof. A roller contacting or gliding member 34 is secured as by bolts such as 44 (FIG. 7) to the back of a vertically movable spindle support member 33 which is attached, in any suitable manner, to the lower end of the piston rod 46 of a reciprocative pressurized fluid motor or cylinder 45 (FIG. 3) which is, in turn, mounted on the upper portion of the outer face of previously mentioned vertical member 31 as by upper and lower clamps 47 and 48 partially surrounding the outer periphery of cylinder 45 and secured to said outer face of member 31 by bolts such as 49. A stop block 50, similar to bearing support block 40, is attached to the second or inner end of horizontal track member 30 and limits the horizontal movement of vertical support member 31 in an inner direction, that is, in a direction towards bridge member 16 (FIGS. 3 and 4).

Spindle assembly 23 also comprises a spindle shaft 51 per se which is rotatably supported on the outer face of spindle support member 33 by a pair of upper and lower pillow blocks 52 and 53, respectively, which are secured to said outer face by bolts such as 54. A rotary motor 55 which is preferably a haudraulically driven motor is also secured on said outer face of support member 33 as by a clamp member 56 fastened to such outer face by bolts such as 57. A pulley 55a is suitably keyed to the output shaft 55b of motor 55 and a suitable drive belt 58 is looped around pulley 55a and a pulley 51a which is suitably keyed to spindle shaft 51. Spindle shaft 51 is preferably a hollow or tubular shaft and a rotary union such as 51b is shown mounted on the upper end of shaft 51 for the purposes of at times, if so desired, supplying negative pressure or vacuum through such union to the lower end of such shaft. The lower end of spindle shaft 51 is shown in FIGS. 2 and 3 of the drawings as provided with a universal coupling 51c for purposes hereinafter discussed. Flexible fluid conduits 55c and 55d are attached to fluid motor 55 and such motor is rotatively driven in clockwise or counterclockwise directions accordingly as pressurized hydraulic fluid is supplied to conduits 55c or 55d, respectively, while the other one of such conduits is connected to a reservoir or fluid sink for the hydraulic fluid as is well known in the art. The driven rotation of motor 55 correspondingly drives spindle shaft 51 as is readily apparent, and the speed of rotation of motor 55 and spindle shaft 51 is dependent on the rate of flow of the pressurized hydraulic fluid supplied to conduits 55c or 55d. The lower portion of spindle assembly 23 is shown in FIG. 1 as enclosed in an enclosure 59 but such enclosure is omitted from FIGS. 3 and 4 of the drawings for purposes of showing the details of the lower portion of the spindle assembly.

From the above description of spindle assembly 23 it will be readily apparent to those skilled in the art that vertically extending support member 31 and, thereby, spindle assembly 23 are horizontally movable or positionally adjustable along the length of horizontally extending rack member 30 by the manual operation or rotation of crank assembly 41. Furthermore, as will be readily apparent to those skilled in the art, spindle shaft 51 and the associated parts or members, such as vertical support member 33, pillow blocks 52 and 53, motor 55 etc., are vertically movable downwardly and upwardly by piston rod 46 of cylinder or reciprocative pressurized fluid motor 45 accordingly as pressurized fluid is supplied to said cylinder through flexible fluid conduits or pipes 45a and 45b (FIGS. 2, 3 and 4) connected to the upper and lower ends, respectively, of cylinder 45.

It is pointed out that, as previously mentioned, spindle assembly 25 is a mirror image of assembly 23 and, therefore, parts or members 30 through 51 of assembly 23 correspond to parts or members 60 through 81, respectively, of assembly 25 with the omission of reference numerals 64, 66 and 74 since no parts or members of assembly 25 corresponding to parts 34, 36 and 44 are shown in the drawings. Similarly, parts or members 75a, 75b, 81a, 81b, 81c, 82, 83, 84, 85, 85a, 85b, 85c, 85d, 86, 87, 88 and 89 of spindle assembly 25 correspond, respectively, to parts or members 45a, 45g,51a, 51b, 51c, 52, 53, 54, 55, 55a, 55b, 55c, 55d, 56, 57, 58 and 59 of assembly 23.

Spindle assembly 24 shown in FIGS. 1 and 2 of the drawings is, as previously mentioned, identical in structure to spindle assembly 23, and includes parts and members 90, 91, 92, 93, 97, 98, 99, 100, 101, 102, 103, 105, 105a, 105b, 106, 107, 108, 109, 111, 111b, 111c, and 119 which correspond respectively to parts and members 30, 31, 32, 33, 37, 38, 39, 40, 41, 42, 43, 45, 45a, 45b, 46, 47, 48, 49, 51, 51b, 51c and 59 of spindle assembly 23. Similarly, and also as previously mentioned, spindle assembly 26 (FIGS. 1 and 2) is identical in structure to spindle assembly 25, and includes parts and members 120, 121, 122, 123, 128, 129, 130, 131, 132, 133, 135, 137, 141, 141b, 141c and 149 which corresponds respectively to parts and members 60, 61, 62, 63, 68, 69, 70, 71, 72, 73, 75, 77, 81, 81b, 81c and 89 of spindle assembly 25.

The structure of the machine or apparatus of the invention having been discussed above in substantial detail, a brief example of the use of the apparatus or machine in a lapping operation will now be set forth.

As an example of the use of the lapping machine comprising the invention, it will be assumed that each of a plurality of similar vessels or dishes such as 150 (FIGS. 2, 3 and 5) and having a planar configuration such as shown in FIG. 5 are to have their external bottom surfaces ground or lapped to make such surfaces as substantially flat as possible. Under such conditions a combined workpiece holder and pressure plate such as 151 (FIGS. 3 and 5) having an outer configuration generally corresponding to the configuration of the inner bottom surface of the vessels such as 150 is rotatably coupled to the bottom of each of the spindle shafts 51, 81, 111 and 141 (FIG. 2) through the respective universal joints 51c, 81c, 111c and 141c. Each of the workpiece holders and pressure plates such as 151 is then lowered into the interior 152 of a suitably positioned and respectively associated vessel such as 150 disposed on lapping surface 11a of lap or lapping disk 11 as shown in FIGS. 2 and 3. The lowering of the workpiece holders and pressure plates is accomplished by slowing supplying pressurized fluid, such as compressed air for example, to conduits 45a, 75a, and 105a, and a similar conduit connected to the upper end of cylinder 135 of spindle assembly 26 but not shown in the drawings for purposes of simplification thereof. The above mentioned universal joints allow for self-leveling of the bottoms of the vessels such as 150 on the lap or lapping surface 11a of lap disk 11, as is believed apparent.

Following the above described positioning of the vessels such as 150 on the workpiece holders and pressure plates such as 151, the crank assemblies 41 and 71 are manually rotated to move spindle assemblies 23 and 25, respectively, horizontally along their respective horizontal arms 17 and 19 to positions shown, for example, in FIG. 1 of the drawings, that is, to positions such that the sharply curved corner areas of the bottom of the vessel at the lower end of spindle shaft 51 will move or rotate through a path whose outer limits extend slightly beyond the outer peripheral edge of lapping surface 11a of disk 11 during rotation of shaft 51, and similar corner areas of the bottom of the vessel at the lower end of spindle shaft 81 will move or rotate through a path whose outer limits extend slightly beyond the inner peripheral edge of lapping surface 11a of disk 11 during rotation of shaft 81, such outer limits of said paths of rotation being indicated in FIG. 1 by broken line circles designated by reference characters 23a and 25a, respectively. (See also FIG. 4 of the drawings). The paths of rotation of the bottoms of the vessels at the lower ends of spindle shafts 51 and 81 also overlap each other a substantial distance as will be readily apparent to those skilled in the art from a brief glance at FIG. 1 of the drawings.

The crank assemblies 101 and 131 are manually rotated to move spindle assemblies 24 and 26, respectively, horizontally along their respective horizontal arms 18 and 20 to positions such that the bottoms of the vessels at the lower end of spindle shafts 111 and 141 will move or rotate through paths of rotation designated in FIG. 1 by broken line circles designated by reference characters 24a and 26a, respectively, during rotation of said shafts 111 and 141, such paths of rotation substantially overlapping each other as well as overlapping the above discussed paths of rotation 23a and 25a. In other words, spindle assemblies 23, 24, 25 and 26 are staggeringly horizontally positioned along the lengths of their respectively associated transverse support arms 17, 18, 19 and 20, respectively, so that the bottom surfaces of the workpieces such as the vessels 150 at the bottom of the respective spindle assemblies will define different but radially overlapping paths of rotation about the central axis of lapping surface 11a of disk 11 when such disk and said workpieces are rotated as discussed below. It is also pointed out that the center of the spindle shaft of each said spindle assembly moves in a radial line extending through said central axis of lapping surface 11a when each respective spindle assembly is horizontally positioned or moved horizontally along its respective transverse arm as mentioned above.

Following the horizontally positioning or adjustment of spindle assemblies 23, 24, 25 and 26 as discussed above, pressurized hydraulic fluid is supplied to the previously discussed fluid conduits connected to the hydraulically driven motors (such as 55 and 85) of the spindle assemblies 23, 24, 25 and 26, while pedestal 13, table 12, lap disk 11 and, thereby, lapping surface 11a of such disk are also rotated by the previously mentioned motor means therefor. The rate of flow of the hydraulic fluid supplied to each of the rotary motors of spindle assemblies 23, 24, 25 and 26 is variably controlled by valve means well known in the art and such rates of flow in the example presently being described are adjusted or selected so that spindle shaft 81 is rotated at the highest speed while spindle shaft 51 is rotated at the lowest speed. The speed of rotation of spindle shaft 111 is less than that of spindle shaft 81 but greater than that of spindle shaft 51, while the speed of rotation of spindle shaft 141 is less than that of both spindle shafts 81 and 111 but also greater than that of spindle shaft 51. In other words, in the group of spindle shafts 51, 141, 111 and 81 taken in that order, the speed of rotation of each succeeding shaft of such group is higher than that of the preceding shaft or shafts of the group. Such variations or differences in speeds of the spindle shafts are intended to compensate for the different distances that the centers of rotation of such shafts are located from the central axis of rotation of lapping surface 11a and the resultant different speeds at which such lapping surface passes under the bottom surfaces of the vessels such as 150 at the bottom of each of the spindle shafts.

The positions of the spindle assemblies having been selected as discussed above, and the speed of rotation of lapping surface 11a and of the spindle shafts having been selected or adjusted as also mentioned above, the apparatus is permitted to reach its said selected speeds and the lapping of the bottoms of the vessels such as 150 then proceeds. If it is decided that such vessels should be pressed against surface 11a with greater pressure, the pressure of the pressurized fluid or compressed air supplied to the upper ends of cylinders 45, 75, 105 and 135 can be increased to supply such greater pressure. Following the completion of the lapping or grinding of the bottoms of a group of the vessels such as 150 the supply of the pressurized fluids to the apparatus is interrupted and the rotating parts permitted to come to a stop. When this occurs, pressurized fluid or compressed air is supplied individually or at the same time to the lower ends of cylinders 45, 75, 105 and 135 and the workpiece holders such as 151 are thereby actuated upwardly out of the interior of the vessels such as 150 which are then removed from lap surface 11a and, if desired, replaced by another group of four vessels such as 150 whose bottom surfaces are to be lapped, polished or ground.

It is pointed out that various types of workpieces can be lapped, ground or polished by changing the workpiece holders attached to the lower ends of the spindle shafts and, in order to accomplish the main object of the apparatus of the present invention, it is necessary to stagger the positions of the spindle assemblies horizontally along the lengths of their respectively associated transverse supporting arms so that workpieces disposed between the lapping surface and said combined workpiece holders and pressure plates define or are so disposed in different but radially overlapping paths of rotation about the central axis of rotation of the lapping surface, and it is then further necessary to select or adjust different or varying speeds of rotation for each of the spindle shafts of the spindle assemblies so that the speeds of movement of all of the workpieces over the lapping surface are substantially equal regardless of the different distances of the spindle shafts from said central axis of the lapping surface. By such an arrangement the lapping surface such as 11a of the apparatus or lapping machine comprising the invention is maintained substantially flat without the use of truing rings, and the necessity for the use of other means for periodically dressing or truing said lapping surface by temporarily removing it from service is substantially reduced or eliminated.

Although there is herein shown and described in detail only one form of an apparatus or machine embodying the invention, it will be understood that various changes and modifications may be made therein with the spirit and purview of the appended claims without departing from the spirit and scope of the invention.

Claims

I claim:

1. In a lapping machine including a lapping disk having an annular horizontal planar lapping surface rotatable about a central axis, an apparatus for lapping a plurality of workpieces on said lapping surface while simultaneously maintaining such planar lapping surface in a flat condition, such apparatus comprising;

A. a bridge member spanning said planar lapping surface and including a plurality of laterally extending arms also extending transversely and generally horizontally above such lapping surface;

B. a spindle assembly supported on a respectively associated one of each of said arms for horizontal movement of each such assembly along the length of its respectively associated arm and each such assembly including,

I. manually operable means for horizontally varying the position of the assembly along its said associated arm,

Ii. a vertically movable and rotatable spindle,

Iii. a first motor for reciprocatively and vertically moving the lower end of the associated spindle toward and away from said lapping surface, and

Iv. a variable speed second motor for rotatably driving the associated spindle; and

C. a combined workpiece holder and pressure plate attached to the lower end of each said spindle for driven rotation thereby, whereby said spindle assemblies can, in relation to each other, be staggeringly horizontally positioned along the lengths of their respectively associated transverse arms with workpieces disposed between said lapping surface and said combined workpiece holders and pressure plates to thereby define different but radially overlapping paths of rotation of said workpieces about said central axis of said lapping surface, and the rotational speed of the workpieces by each said workpiece holder and pressure plate can be varied to render the speeds of movement of all said workpieces over said lapping surface substantially equal to thereby maintain such lapping surface flat while simultaneously lapping said workpieces.

2. Apparatus in accordance with claim 1 and in which each said first motor comprises a gaseous fluid actuated cylinder and associated piston rod.

3. Apparatus in accordance with claim 1 and in which each said variable speed second motor comprises a hydraulic driven motor.

4. Apparatus in accordance with claim 3 and in which each said first motor comprises a gaseous fluid actuated cylinder and associated piston rod.

5. Apparatus in accordance with claim 1 and in which the path of said horizontal movement of each said spindle assembly along the length of its said respectively associated arm parallels said lapping surface in a radial line extending from said central axis of such lapping surface to the outer periphery thereof.

6. Apparatus in accordance with claim 2 and in which the path of said horizontal movement of each said spindle assembly along the length of its said respectively associated arm parallels said lapping surface in a radial line extending from said central axis of such lapping surface to the outer periphery thereof.

7. Apparatus in accordance with claim 3 and in which the path of said horizontal movement of each said spindle assembly along the length of its said respectively associated arm parallels said lapping surface in a radial line extending from said central axis of such lapping surface to the outer periphery thereof.

8. Apparatus in accordance with claim 4 and in which the path of said horizontal movement of each said spindle assembly along the length of its said respectively associated arm parallels said lapping surface in a radial line extending from said central axis of such lapping surface to the outer periphery thereof.