US3393474A - Lapping and polishing machine - Google Patents

Description

July 23, 1968 R. D. BUSWELL LAPPING AND POLISHING MACHINE 2 Sheets-Sheet 1 Filed March 1, 1965 INVENTOR.

ROBERT D'BUSWELL Jr Cb/ ATTORNEY 2 3 Y w a c r m 5 =9: 4/ M 5 c July 1968 R. D. BUSWELL 3,393,474

LAPPING AND POLISHING MACHINE Filed March 1, 1965 2 Sheets-Sheet 2 TIL j: El-

I I .'B

\ INVENTOR.

4 P ROBERT D-BUSWELL ATTORNEY United States Patent 3,393,474 LAPPING AND POLISHING MACHINE Robert D. 'Buswell, 1351 Crespi Drive, Pacifica, Calif. 94044 2 Filed Mar. 1, 1965, Ser. No. 436,193

11 Claims. (Cl. 51-120) ABSTRACT OF THE DISCLOSURE A lapping and polishing machine having a housing provided with arotatable dirt shield on its upper rim surface,'and a plurality of lap assemblies rotatably mounted on the shield for turning about their respective axis, the shield and lap assemblies being movable around the axis of the. housing. A support ring is carried by the housing for up and down adjustments and bears against bases of the laps to support the latter, the lap bases having slotted skirts to condition and maintain contacting surfaces between the lap bases and support ring flat during operation of the machine.

As an object of this invention, it is proposed to provide a lapping and polishing machine capable of working annular areas, either upon or within a workpiece, at such a location as to be inaccessible to the lapping and polishing provisions of conventional lapping machines. The principal object of this invention is to provide multiple laps that act, in unison against a workpiece, these laps being so disposed in relation to the workpiece that the latter acts as a conditioning ring for maintaining permanent flatness. of each of the multiple laps, and these same laps may bring about a state of flatness to the workpiece.

Moreover, it is proposed that the multiple laps be so supported within the machine that normal running Wear will provide for permanent flatness of their supporting means, thereby establishing conditions unique to a machine that will remain permanently conditioned, without requiring adjustment or need of a flatness check for its entire life.

As a still further object of this invention, it is proposed to provide a lapping and polishing machine that requires no special skill to use. The machine will consistently produce surface flatness within millionths of an inch with a. mirror finish from which monochromatic light band readings may be taken without further polishing.

Another object of this invention is to provide compactness of design which will contribute to economy of manufacture, distribution and mounting space.

Other objects and advantages will appear as the specification proceeds, and the novel features of the invention will be particularly pointed out in the appended claims.

Drawings For a better understanding of the invention, reference should be had to the accompanying drawings, forming part of this specification, in which:

FIG. 1 is a perspective view of my lapping and polishing machine, without workpiece adaptors being shown.

, FIG. 2 is a partial top plan view of the lapping head, the workpiece adaptors being omitted, and this view showing the directional movement of external parts.

'FIG. 3 is a partial cutaway and partial sectional view of the lapping head, with a work-positioning adaptor shaft being disclosed to rest against the phantom line presentation of the gear motor shaft.

, FIG. '4 is a View of the top portion of FIG. 3 and including, in phantom lines,the outline, of a cutting plane through the center section of a typical workpiece, the

3,393,474 Patented July 23, 1 968 latter having a suitable adaptor bushing to locate correct working position upon the machine.

FIG. 5 is an isometric half section of the basic lapping head, showing the gear motor driving shaft and bearing cap in phantom line.

While I have shown only the preferred embodiment of my invention, it should be understood that various changes, or modifications, may be made within the scope of the appended claims, without departing from the spirit thereof.

Detailed description Referring now to the drawings in detail, the lapping and polishing machine defines a lapping head designated generally at A, which is mounted directly over a conventional gear motor B, or other suitable driving means. Of course, the size of the lapping head, and the size and speed of the gear motor, will be determined by the service to which the machine is put during use.

As disclosed in FIG. 5, the lapping head A defines tubular cylindrical housing 1 that rests loosely on top of the gear motor B. The upper surface 2 of the gear motor cap is machined flat to provide a level surface for the lower end of the housing 1 to rest upon for support thereby. It will be noted that a series of milled depressions 3 are fashioned in the base of the housing 1 so as to fit loosely around and over bearing cap retaining bolt heads 4, thus preventing rotation of the housing relative to the gear motor.

In FIGS. 3 and 5 of the drawings, the housing 1 has been illustrated as being disposed concentrically around the vertical axis of the drive shaft 5 of the gear motor B, this shaft projecting vertically into the interior of the housing. Moreover, a drive shaft extension 6 in the nature of a tubular spindle has its lower section telescoped downwardly over the shaft 5, this shaft extension defining a bore section 8 at its lower end to fit snugly over the shaft 5. The extension 6 is secured to the gear motor shaft 5 by a set-screw 7. Thus, the drive shaft extension 6 will be rotated by the gear motor B whenever the latter is operating. As will be apparent as the specification proceeds, the extension 6 is utilized for driving the laps for lapping and polishing operations on workpieces.

It will be seen that the inside diameter of the housing 1 is threaded, as at 9, from its bottom to adjustably receive a large thrust nut 10', the latter being preferably made of fiber, and the rim of this nut being formed with threads so that the nut may be raised or lowered relative to the housing. This nut rests against a thrust bearing 11 on which a support ring 12 is mounted so as to permit the latter to rotate freely. The support ring is disposed concentrically around the drive shaft extension 6 and spaced radially outwardly beyond the latter. This support ring may be made of mehanite cast iron, and is constitutes supports for a plurality of lap assemblies designated generally at C. These lap assemblies are arranged radially with respect to the vertical axis of the gear motor shaft 5, and are separated circumferentially from one another and are operable in unison.

Each lap assembly C consists of four parts: lap base 13, lap drive ring 14, lap 15, and lap cuff 16. The number of lap assemblies utilized is determined by the size of each such assembly in relation to the size of the entire machine and the service requirements of the latter.

It will be apparent that each lap 15 somewhat resembles a castellated nut and it may be made ofmehanite process cast iron. Its upper portion has slots 17 fashioned therein, which have been shown as being'radially disposed relative to the vertical axis about which the lap rotates. The lower part of each lap 15 is formed with a bore 18 having left-hand female threads into which a lefthand threaded stem 19 may be screwed, this stem being 3 formed integral with and projecting upwardly from the lap base 13.

The lap bases 13 may be made from nylon, and the bottom of each is formed with a recess 20 extending upwardly thereinto, each recess being slight in depth and having a diameter slightly greater than the width of the rim portion of the support ring 12 upon which the lap bases bear (see FIGS. 4 and An annular skirt 21 is thus created at the circumference of the lower face of each lap base 13, this skirt having slots 22 formed therein in much the same manner as the slots 17 (see FIGS. 3, 4 and 5).

This design on the lower part of each lap base 13 cre ates a stable, low drag, self-cleaning surface to bear against the top rim surface of the support ring 12 and, in due process of normal wear, acts as a conditioning ring to maintain the top surface of the support ring perfectly and continuously flat.

It will be observed from FIGS. 4 and 5 that each lap base 13 is formed with a circumferentially extending groove 23 to accept a conventional resilient rubber O- ring, which constitutes the drive ring 14- previously mentioned. The functions of these rings will now be described.

The drive shaft extension 6 has an annular V-shaped groove 24 formed in the exterior surface thereof near its upper end, and into which the inner peripheral section of the drive rings 14 project with a frictional fit. Moreover, the inner diameter of the tubular housing 1 is formed with a frusto-conical inner surface 25 at its upper end, which tapers inwardly in an upward direction. The outer peripheral sections of the drive rings 14 bear against this conical surface 25 with a frictional fit. The upper section of the V-shaped annular groove 24 flares outwardly in an upward direction, while the lower section of this same groove flares outwardly in a downward direction.

As suggested by the arrow 26 in FIG. 2, the drive shaft extension 6 is turned in a counterclockwise direction when the gear motor B is operating. On account of the wedged position of the drive rings 14 between the V-shaped groove 24 of the extension 6 and the frusto-conical inner surface 25 of the stationary housing 1, the lap assemblies C are rotated by a frictional drive in a clockwise direction, each about its own vertical axis, as suggested by the arrows 27 in FIGS. 2 and 5.

As shown in the drawings, the upper driving section of the V-shaped annular groove 24 in the drive shaft extension 6 and the frusto-conical surface 25 of the stationary housing 1 may be bevelled at opposite 30 angles from the vertical. This willmaintain a constant downward thrust upon the drive rings 14 and thereby cause the lap assemblies C to rotate about their respective vertical axis during operation of the gear motor B. This will occur even when the benefit of the weight of a workpiece D is not present over the lap assemblies (see FIG. 4).

Of course, it will be appreciated that manipulation of the thrust nut will raise or lower the lap assemblies C in relation to groove 24 and surface 25. For the purpose of turning the thrust nut relative to the housing 1, recesses 28 are formed in the lower face of the thrust nut to provide finger grips to aid in turning the thrust nut. Correct drive ring tension is thus obtained at assembly of the machine.

Also, the thrust nut 10 is used to compensate for wear on the top rim surface of the support ring 12, the bottom surfaces of the lap bases 13, or on the drive rings 14. At assembly, the drive shaft extension 6 is positioned so as to have its top end 29 disposed in a plane coinciding with the top rim surface 30 of the housing 1 (see FIGS. 3 and 5).

The lap assemblies C maintain equal spacing from each other by the lap bases 13 protruding upwardly through equally spaced holes 31 in a dirt shield 32. The latter drops down sufiiciently over the lap assemblies as to bear against the circumferences of the lap bases 13 at points just above and even resting on the drive rings 14, if desired.

The dirt shield 32 maybe made from Plexiglas so that its transparency will permit visual inspection of parts within the machine, without requiring removal of this shield.

Of course, the friction drive previously described must be kept free from lubrication, or lapping vehicles and moisture from compounds used on the laps 15. The flared lap cuffs 16 will effect a moisture-tight seal between the laps 15 and the upper face of the dirt shield 32. Each culf 16 is paper-thin and may be made of nylon, and originally have a flat washershape. The inside diameter should be slightly less than the outside diameter of the lap 15. When the cuff is applied over the lap 15, its inside diameter is pressed into a small annular groove 33 formed in the exterior of the lap (see FIG. 4). Actually the cult is stretched over the lap and will flare as shown in the drawings.

Due to the elastic character of nylon, the outside diameter of each cuff 16 will contact and flare outwardly over the upper face of the dirt shield, and consequently is held there in a state of compression and a moisturetight seal results. The tightly fitting inside diameter of each cuff acts to rotate with its lap 15.

The dirt shield 32 is formed with a central hole 34, the diameter of which corresponds with the diameter of the upper bore section 35 in the drive shaft extension 6 (see FIGS. 3, 4 and 5 and the purpose of this arrangement is to provide for accommodation of workpieces D having a central shaft, or a workpiece formed with a central hub protrusion 36 shown in FIG. 4.

With particular reference to FIG. 4, the surface 37 represents the annular surface within the workpiece D being conditioned by the laps 15. Bushing 38 shown in this view is made of such shape that it will fit into a depressed portion 39 of the workpiece, and it is formed with a central hole 40 by which the bushing and annular surface 37 may become radially centered in relation to the laps. It will be noted that the surface 37 is disposed on the interior of the workpiece, and the latter actually fits down over the upper portion of the laps 15.

In FIG. 4, there is illustrated an adaptor shaft 41 that passes from the upper end of the gear motor drive shaft 5 and up through the'bore of the extension 6 and thence through a central hole 42 formed in the workpiece. The adaptor bushing 38 thus provides correct locating means for the workpiece. Obviously, workpieces not having a central hole may be similarly located by the use of adaptors acting between the bottom of the workpiece and the bore of the extension drive shaft 6 from which the shaft 41 may be easily removed.

Downward working pressure against the laps 15 is provided by the weight of the workpiece D. Of course, lightweight workpieces may require additional Weight, and enlargement of the adaptor bushing 38 is a convenient method of adding more weight.

Particular attention is called to the fact that the laps 15 project above the dirt shield 32 and are unobstructed for mounting the workpieces D thereover, even though the latter are recesses on their underneath sides, as in FIG. 4. As can be seen, the height of these laps is determined by the depth of the recess 43 in the workpiece that the laps are required to meet, if such recesses are provided. Also, the length of the central hub 36, if any, will become a factor in determining the height of the laps.

In FIG. 2, the arrow 26 shows how counterclockwise rotation of the drive shaft extension 6 imparts clockwise rotation to each of the individual laps 15 about its own vertical axis, as suggested by the arrows 27. Since the outer peripheral sections of the lap drive rings 14 act against the frusto-conical surface 25 of the stationary housing 1, as previously explained, the laps 15 will travel with the dirt shield 32 around the vertical axis of the lapping head A in a counterclockwise direction, as indicated by the arrows 44 in FIGS. 2 and 5, with the-clockwise rotation of each individual lap continuing around its axis. Consequently, the workpiece D resting on the top of these laps will rotate counterclockwise.

The traveling speed of the lapping head A is constant, but because of the individual rotational movement of the laps 15, the traveling speed or rotational movement of the workpiece D will vary; it may be faster or slower, depending upon the magnitude of the surface irregularities of the workpiece. However, as its surface 37 nears acondition of flatness, the workpiece will assume a .slow and steady speed. On account of the drag of its own weight along with forces acting on it, the workpiece Will maintain a slower traveling speed than the laps 15. Consequently, these laps will be working over continuously changing areas, and a flatness Within millionths of an inch can be obtained.

This arrangement'of multiple laps acting upon a single workpiece is unique in that the flatness generatedupon the workpiece by the multiple laps is reverted back to the multiple laps by the action of the workpiece, thereby creating a condition of permanent flatness of the laps. j

It should be remembered that the support ring 12 is free to rotate upon the thrust bearing 11, and under the pressure along with the rotational forcesof the lap bases 13, the support ring assumes a counterclockwise rotation, as indicated by the arrow 45 in FIG. 5, in much the same manner as does the workpiece D that rides on the lap assemblies C. Thus the contacting surfaces between the support ring 12 and the lap bases 13 continuously act through normal wear to keep each other flat so that no distortion exists to be transferred to the working end or top of the lap assemblies. Accordingly, this is a self-flattening lapping machine that never requires any maintenance, other than infrequent replacement of worn parts, or a'very brief cleaning of its external parts on occasions.

I claim:

1. In a lapping and polishing machine:

(a) a cylindrical tubular housing defining a axis; 1

(b) a dirt shield rotatably mounted over an upper rim surface of the housing, and said shield being fashioned with a plurality of holes therein, said holes being spaced radially of the axis of the housing and further being spaced circumferentially from one another;

(c) a multiplicity of individual laps, each having a lap base rotatably supported in one of the holes in the dirt shield, and each lap projecting above the dirt shield;

(d) means operable to rotate each lap in one direction about its own axis, and to rotate the dirt shield in the opposite direction to carry the laps therewith around the axis of the housing;

(e) and the outer peripheral sections of all of the laps remote from the axis of the housing being laterally unobstructed and said laps being unobstructed from above, whereby a workpiece having a recess in its underneath side may be mounted over all of said laps at one time, with the laps extending upwardly into the recess of the workpiece;

(f) each lap having a resilient cuff secured thereto above the dirt shield, and bearing against the latter so as to provide a moisture-tight seal over the hole in which its lap base is positioned;

(g) each lap being formed with an annular groove in its exterior adjacent to the upper surface of the dirt shield, and each cuff being washer-shaped and having an inside diameter slightly less than the outside diameter of the lap, whereby the cuff must be stretched over the lap to which it is applied and the inside diameter portion of the cuff being pressed into the annular groove thereof.

2. In a lapping and polishing machine:

(a) a tubular housing defining an axis;

vertical (b) a dirt shield rotatably mounted over an,upper rim surface of the housing; (c) a multiplicity of individual lap assemblies rotatably mounted on the dirt shield, each for rotation about its own axis;

(d) each lap assembly having a lap projecting above the dirt shield, and further having alap base extending below said shield;

(e) means operableto rotate each lapassembly about its own axis, and to rotate the dirt shield and carry the lap assemblies therewith around the axis of the housing;

(f) and a support ring rotatably supported in the housing, and having a top rim surface bearing against the lap bases to constitute a support for the latter.

3. The lapping and polishing machine, as set forth in claim 2;

(g) and in which each lap base has a slotted skirt bearing against the top rim surface of the support ring so as to condition and maintain said top rim surface perfectly .and continuously fiat and said same rim surface will maintain a state of flatnesson the slotted skirt, as the lap bases and support ring are rotated.

4. The lapping and polishing machine, as set forth in claim 2;

(g) and in which means are provided for adjusting the support ring up and down relative to the housing.

5. The lapping and polishing machine, as set forth in claim 2;

(g) and in which a thrust bearing is provided under the support ring;

(h) and a thrust nut mounted underneath the thrust bearing, said nut having threaded engagement with the housing, whereby the thrust bearing and support ring may be adjusted vertically by turning the thrust nut.

6. In a lapping and polishing machine:

(a) a tubular housing defining an axis;

(b) a dirt shield rotatably mounted over an upper rim surface of the housing;

(c) a multiplicity of individual lap assemblies rotatably carried by the dirt shield, each for rotation about its own axis;

(d) each lap assembly having a lap projecting about the dirt shield, and further having a lap base extending below said shield;

(e) means operable to rotate each lap assembly about its own axis, and to rotate the dirt shield and carry the lap assemblies therewith around the axis of the housing;

(f) a support ring rotatably supported in the housing, and having a top rim surface bearing against the lap bases to constitute a support for the latter;

(g) each lap base having a slotted skirt bearing against the top rim surface of the support ring so as to condition and maintain said top rim surface perfectly and continuously flat and said same rim surface will maintain a state of flatness on the slotted skirt, as the lap bases and support ring are rotated;

(h) a thrust bearing being provided under the support (i) and a thrust nut mounted under the thrust hearing, and being adjustable up and down relative to the housing to carry the thrust bearing and support ring therewith.

7. In a lap and polishing machine:

(a) a tubular housing defining an axis;

(b) a dirt shield rotatably mounted over an upper rim surface of the housing;

(0) a multiplicity of individual lap assemblies rotatably carried by the dirt shield, each for rotation about its own axis;

(d) each lap assembly having a lap projecting above the dirt shield, and the laps being unobstructed from above, whereby a workpiece may be placed over all of the laps at one time so that a selected surface of the workpiece may be lapped and polished;

(e) means operable to rotate each lap, and to carry all of the laps around the axis of the housing;

(f) said operating means including a tubular drive shaft extension aligned axially with the housing;

g) and an adaptor shaft removably telescoped into the bore of the drive shaft extension and extending above the dirt shield for passage through a central hole in the workpiece to thereby center the latter on the dirttshield;

(h) the adaptor shaft having a weighted bushingslidably disposed thereon above the workpiece to urge the latter downwardly.

8. In a lap and polishing machine:

(a) a stationary tubular housing having a frusto-conical inner surface;

(b) a drive shaft extension mounted axially in the housing, and being coupled to a source of rotary power for being rotated thereby;

(c) said drive shaft extension having an annular groove formed in its exterior surface;

(d) a shield rotatably mounted over an upper rim surface of the housing;

(e) a multiplicity of individual lap assemblies rotatably carried by the shield, each for rotation about its own axis;

(f) each lap assembly having a lap projecting above the shield, and further having a lap base extending downwardly through a hole in the shield, whereby the lap assemblies will be carried with the shield when the latter is rotated;

(g) each lap base having a lap drive ring secured thereto by which the lap base may be rotated;

(h) each drive ring having an inner peripheral section projecting into the annular groove in the drive shaft extension with a frictional fit, and further having an outer peripheral section bearing against the frustoconical surface of the housing with a frictional fit, whereby each lap assembly will be rotated around its own axis and the shield and its lap assemblies will be carried around the axis of the housing, when the drive shaft extension is rotated.

9. The lap and polishing machine, as set forth in claim 8;

(i) and in which the frusto-conical surface of the stationary housing tapers inwardly in an upward direction, and the annular groove in the drive shaft extension has an upper portion that flares outwardly in an upward direction; 1

(j) and means operable to raise the lap bases relative to the stationary housing so as to wedge the drive rings against the frusto-conical surface of the housing and the upper portion of the groove in the drive shaft extension.

10. The lap and polishing machine, as set forth in claim 8;

(i) and in which the frusto-conical surface. of the stationary housing tapers inwardly in an upward direction, and the annular groove in the drive shaft extension has an upper portion that flares outwardly in an upward direction;

(j) and a support ring rotatably supported in the housing, and having a top rim surface bearing against the lap bases to constitute a support for the latter.

11. The lap and polishing machine, as set forth in claim 10;

(k) and in which means are provided for adjusting the support ring up and down relative to the housing to thereby vary the tension on the drive rings.

References Cited UNITED STATES PATENTS 835,631 11/1906 Mooney 51-120 X 862,747 8/1907 Miller 51-120 X 1,430,214 9/1922 Carrie 51--120 2,023,572 12/1935 Brendel 5l43 X 2,371,582 3/1945 Hanchett 51120 X 2,649,669 8/1953 Tobis 51120 X 2,841,926 7/1958 Lebus 51128 X 3,137,977 6/1964 Graves 5l119 3,284,960 11/1966 Day 51120 HAROLD D. WHITEHEAD, Primary Examiner.

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