US2945331A - Lapping machine - Google Patents

Description

July 19, 1960 1.. J. LA BARRE ETAL 2,945,331

LAPPING momma Filed ma 16, 1957 3 Sheets-Sheet 1 'INVENTORS Lawrence J La flan-e A TTORNE Y:

' LAPPING MACHINE Filed May 16, 1957 3 Sheets-Sheet 2 FIEJ E INVENTORS lawns/7C6 J La fiarre BY M/i/l/am Girdner ATTORNEYS 1960 L. J. LA BARRE ETAL I LAPPING MACHINE Filed'uay 7 3 Sheets-Sheet 3 LAPPING -MAGHINE Lawrence J. La Barre, Mountain, View, and'William I.

Girdner, Mcnlo Park, Calif, assignors to Hewlett- Packard Company, Palo Alto, Calif, a corporation of California Filed May 16, 1957, Ser. No. 659,513

4 Claims. 01. 51-131 This invention relates generally to lapping machines.

'It is a general object of the present invention to provide an improved lapping machine into which the Work may be rapidly inserted and removed for grinding and surfacing on a mass production basis, and in which the lap surface is continuously conditioned during the lapping operation.

Another object of the present invention is to provide a lapping machine in which a conditioning ring extends over the edges of the lap and in which the pressure hetween-the conditioning ring and the lap may be controlled to condition the lap as desired while the work is being operated upon.

It is another object of the present invention to provide a lapping machine in which the lap surface is continuously in contact with a conditioning ring which extends over the edges of the lap and which includes means for controllably applying pressure to the ring whereby the pressure at the inner or outer edges of the lap surface may be increased as desired to control the shape of the lap surface.

It is another object of the present invention to provide a lapping machine in which the lap surface is continuous- 1y conditioned by a conditioning ring rotatably mounted on its axis and in which means are provided for coutrolling the pressure between the conditioning ring and the inner and outer edges of the lap surface whereby the lap surface may be conditioned to be .plane, concave for convexas desired.

It is still another object of the present invention to ."p oyi-de a lapping machine in which a plurality of work j holders are pivotally mounted and spaced from the lap surface and which include means for controlling the spacingo'f thework holders from the lap surface.

These and other objects of the invention will become more clearly apparent from the following description taken in conjunction with the accompanying drawing.

Referring to the drawing:

Figure l is a top plan view of a lapping machine in accordance with the invention;

Figure 2 is a side elevational view partly in section takenalong the line 2-2 of Figure 1;

Figure 3 is an enlarged view taken along the line 3-3 of Figure .1 and showing the work holder stem locking and positioning means;

Figure 4 is an enlarged view of the stern locking means taken along the line 4-4. of Figure 3;

' Figure 5 is an enlarged sectional view taken along the line 5-5 of Figure 1 showing the rotatable wear ring and the means for controlling the pressure between the wear ring and the inner and outer surfaces of the lap;-

Figure 6 is an enlargedview of the pivotal mount for 7 the wearring; and

Figure-7 is an enlarged-view showing the lower end of the work holder stem, the bearings associated therewith :aud-iheworkholder; g e

:A supporting gfii'ame designatedz generally by the refer- Patented July 19, 1960 'the legs 12. Reinforcingchannels 14 are disposed at the upper end of the legs and serve tosupport the lap, as will be presently described. A plate 16 extends across the apparatus and rests on a pair of the members 13. The plate 16 serves to support an electric motor 17 and the gear reduction box 18. A suitable pulley 19, for example, a double groove V-belt pulley, receives the V- belts 21. The belts engage the pulley 22 which is attached to the'turntable shaft. The .pulley 22 is suitably attached to the lower end of the shaft 23 as, for example, by the collar 24 and set screws 26.

The turntable, work holders and related parts are carried by the angle irons 2.7 and 28 which extend trans versely across the framework and are supported by the channels 14. The aforementioned parts are supported by suitably securing the shaft housing 29 to the angles 27 and 28. For example, the housing 29 may extend through a plate 32 and be suitably welded thereto. Bolts 33 serve to secure the plate to the angles 27 and 28. The turntable shaft 23 extends downward into the housing 2.9 and is engaged by the inner race of the upper and lower bearings 34, 36 which are carried within the housing. The spacer 37 serves to hold the bearings in spaced relationship. The lower bearing is provided with a suit able seal 38. A thrust bearing 39 has an upper race 'which is secured to the shaft 23. The lower race is engaged in the annular recess 41 formed in the upper end of the housing 29. A gasket 42 and a drip ring 43 are interposed between the shoulder 44 formed on the shaft and the upper race of the bearing 39.

The turntable 46 is received by the upper end of the shaft (Figures 2 and 5) and rests on the shoulder 44 formed on the shaft. The shaft is threaded at 47 to receive the lock nut 48 which serves to secure the turntable to the shaft. A suitable driving pin 49 is secured to the shaft and extends through the slot 51 formed in the table hub.

The turntable comprises an upper lapping surface 52 which is provided with a plurality of radial grooves 53 alternate ones of which extend completely across the lap ping surface. The grooves act in conjunction with the work and conditioning ring, to be presently described, to maintain the surface of the lap clean. The grooves are deeper at the outer edge of the lap surface whereby the oil and grit tends to flow outwardly and into a collecting trough to be presently described. Referring particularly to Figure 2, the grooves 53 are shown extending from the inner edge of the lapping surface outwardly and downwardly to the outer edge. A plurality of web-like reinforcing members 54 extend between the hub of the turntable and the lower edge of the table and serve to reinforce the same.

The oil and grit which flow outwardly from the lapping surface drips down the outer edge of the table into the trough 56. The trough 56 has an outer edge which extends upwardly a short distance above the lower edge of the turntable and an inner edge which extends upwardly and is spaced from the lower edge of the turntable. To prevent the migration or flow of oil inwardly along the lower surface-of the turntable, a pairof grooves 57 are formed in the lower side near the periphery of the internal diameter which serves to accommodate the bear- " ings 67 and 68 which are held in spaced relationship by the spacer 69. The lower bearing 68 has its inner race abutting against the shoulder formed between the threaded portion 47 of the shaft 23 and the upper-portion. Work holder arms 71 are suitably secured to the assembly designated generally by the reference numeral 72. The arms '71 may, for example, be secured thereto by means of bolts 73. a

Referring particularly to Figure 5, the details of the assembly 72. are fully illustrated. The assembly'comprises an anchor sleeve 74 which is adapted to slide over the pivot column and to be secured thereto as, for example, by means of the set screws 76 which ride into accommodating indentations formed on the column. The upper portion of the sleeve is threaded to receive the anchor sleeve nut 77. The anchor sleeve nut provides an adjustment for the vertical height of the work holder hub 79. The work holder hub- 79 has an eccentric recess 81 formed in its upper end. A lock ring 82 having an eccentric portion adapted to fit into the recess fits over the hub. Upon turning movement of the ring by means of a spanner wrench which engages the holes 83, the members 79 and 82 are locked to the pivot column 66.

The work which is operated upon by the surface of .the lap is held in a plurality of work holders 86 illustrated in Figures 1, 2 and 7. The work holders comprise plates having work receiving openings therein into which the work 87 is placed, as illustrated in Figure 7. The bottom surface of the work is frictionally engaged by the lap surface and ground to a true surface. As will be presently described, means are provided for spacing the work holder above the surface of the lap where they do not wear the lap. Each of the work holders is rotatably mounted on a vertical shaft or stem which is suitably engaged by one of the arms 7&1. The arms and stem prevent the work holder from rotating with the lap. As is apparent, the'work which is operated upon by the outer periphery of the lap is in contact with a portion of the lap which is traveling at a greater velocity than the inner surface. As a result, a torque is developed which rotates the work holder. Thus, each piece of work is operated upon by various portions of the lap surface. Further, as will be presently described, the work itself serves to condition or dress the lap.

The work holder mount (Figure 7) may, for example, include a bearing holder 88 which is press fit to the shaft or stem 89 and which serves to hold the bearings 91 and 92. A short shaft 93 has its upper end press fit into the inner race of the bearings and its lower end press fit into the head 94. The head comprises a pair of cylinder-like members which are interconnected at the top. The lower outer edge of the outer cylindrical memberis provided with a circumferential notch 96 which serves'toreceive the work holder disc 86. The outer cylinder is longitudinally slotted. A plurality of set screws 97 which bear against the inner cylinder serve to urge the outer cylinder outwardlyto firmly hold the disc 86 in the groove 96.

The stem 89 extends upwardly through the holding arms 71 shown in detail in Figures 2 and 3. The shaft is locked in a vertical position by means of a stern lock 98 which includes cutout 99. The stem lock is inserted in an accommodating hole formed in the arm 71. A nut 101 engages the threaded outer end of the stem lock. Upon turning movement of the nut 101, the cutout portion of the stem lock is cammed against the shaft 89 and s r c he s me.- i

Means are provided for accurately positioning the work holder above the lapping surface. A hub 102 provided with an eccentric opening 104 serves to receive an eccentric nut 103 to form a stem lock. By turning movements of the nut and hub with respect to one another, the stem lock is locked to the shaft; A raised disc 107 is mounted on the arm 71 by means of the bolt 108. The disc 107 has a varying thickness whereby the same may be rotated to urge the stem lock upwardly to lift the stem. In

operation, the work holding disc is placed on the lap surface and the stem lock is locked. The disc is then rotated to lift the stem a predetermined amount corresponding to the height of the incline of the disc. The stem lock nut is then rotated and the stem is locked to the arm. In this manner the work holding disc is'spaced a suitable predetermined distance from the surface of the lap. The pivot column 66, arms 71 and the holders are prevented from turning with the lap by the bar 109 which engages the post 110. The post 110 is secured to the frame.

Thus, it is seen that a work holder arrangement is provided in which the work holder may be accurately spaced from the lap surface and in which the work holder is free to rotate about its axis.

As is well known, as the work is operated upon by the lapping surface, there is a tendency for the lapping surface to become uneven. In many types of lapping machines, the work is removed after a predetermined period of operation and the surface of the lap is dressed or conditioned. In the present machine, asuitable wear ring continuously engages the surface of the lap. The wear ring is of such a weight and proportions and is so arranged that it continuously conditions the lap surface as the work is being operated upon.

Referring now more specifically to Figures 1, 2 and 5, the conditioning arrangement is illustrated. A relatively heavy conditioning ring 111 has its lower edge provided with a plurality of radial slots 112. The ring is of such dimensions that it overhangs the inner edge 113 and the outer edge 114 of the lap surface. The conditioning means is in the form of a ring and suitable mounting means, for example, a mounting plate or cover 116 is suitably secured thereto. A bearing holder 117 is secured ito the plate and accommodates the bearings 118 and 119. The conditioning ring stem 121 extends into the bearings.

The stem is provided with an elongated slot 122 which serves to' accommodate a pin 123 whereby the stem is pivotally held by the pin. The pin 123 is suitably secured to the fork of the inwardly extending arm 124, as for example, by bolts 126. The arm 124 is suitably mounted to a channel 127 (Figure 1) which extends downwardly and is secured to the frame 11. The arm 124 prevents the conditioning ring from rotating with the lap. The upper portion of the stern 121 is provided with a threaded portion of reduced diameter. A weight bar 128 fits over this portion and the nut 129 serves to secure the same to the stem 121. The bar provides means for controlling the pressure between the inner or outer edges of the lap surface and the conditioning ring. Weights are placed on the weight bar to control the pressure between the wear ring and the inner and outer surfaces of the lap. When a weight is placed on the bar toward the center 'of the lapping machine, the pressure between the Wear ring and. the lap surface at the inner edge of the lap is increased. The inner edge of the lap is worn more than the outer edge and the lap becomes concave. Similarly, if the weight is placed on the bar toward the outside of the machine, the outer edge wears to greater extent than plane or flat by properly positioning the weight on the weight bar.

A work holder 141 of the type previously described is rotatably mounted on the shaft 121 by meansof bear- Simple and efilcient means is ings (not shown). The work holder has an outside diameter which is less than the inside diameter of the wear ring whereby it may rotate independently of the same. Means (not shown) is provided for positioning and holding the work holder above the lap surface whereby it rotates free of the same.

Additional work holders 144 are rotatably supported by a shaft 145 which extends upwardly and is engaged by the arm 146. The arm and work holder are supported by a vertical member which is secured to the frame 12. These work holders are disposed in the open portions of the lap which exist between the relatively large work holders, previously described, and between the large work holders and the wear ring. It is apparent that additional work holders may be employed since the larger work holders and the wear ring are held at a fixed radial distance from the center of the lap.

The addition of the smaller work holders 144 and the work holder 141 disposed in the work ring, increases considerably the surface area of the lap which is employed.

A tank 131 holds the oil and grit. The tank is supported by the plates 132 which are suitably attached to the frame and extend upwardly therefrom. The motor 133 drives the agitator 134 through the speed reduction gear 136. The oil and grit are fed from the tank onto the lapping surface along the wire 1137.

Operation of the lap is as follows. The work holders are positioned about the surface of the lap as previously described. The work is placed in the work receiving openings of the work holders as illustrated in Figure 7 wherein a number of wave guide sections 87 are shown in place. The turntable is rotated to produce relative movement between the lap surface and the work pieces. Oil and grit are continuously supplied to the surface. As privously described, the oil and grid flow outwardly along the grooves 53 into the trough 56. Rotation of the lap induces rotation of the work holders and work whereby the same come into contact with different portions of the lap as the lapping operation progresses. This turning movement of the work holders and work aids in maintaining the lap surface in condition.

Any unevenness of the lap surface is corrected for by the conditioning ring 111 which is rotatably mounted and which has its work surface in contact with the surface of the lap. As previously described, the conditioning ring stem 121 is pivotally mounted. A weight bar is secured to the upper end of the stem and provides means for controlling the pressure between the work surface of the wear ring and the lap surface. Thus, during operation a weight is placed on the weight bar and is moved radially, inwardly and outwardly, as desired, to maintain the surface of the lap concave, convex or flat. It has been found that once the weight is properly positioned the lap may be operated for many hours without readjustment of the position of the weight.

Thus, it is seen that we have provided an improved lapping machine in which the work holders do not cause wear of the lap surface since they are spaced therefrom. provided for conditioning the surface. We have provided a convenient means for controlling the lapping surface without changing the position of the work or conditioning ring. Said means consists of a weight bar which serves to control the pressure between the conditioning ring and the inner and outer edges of the annular lap surface. Further, we have provided a means for making a great percentage of surface of the lap available for work.

We claim:

1. A lapping machine comprising a frame-like structure, a turntable rotatably mounted on said frame-like structure and having an annular lapping surface, means for driving said turntable, work holding means spaced from the surface of said table and including work receiving openings, means for rotatably mounting said work holding means, means preventing movement of the work holding means with the turntable, a conditioning ring extending over the inner and outer edges of said surface, means for rotatably mounting said conditioning ring, said mounting means including a stem, means pivotally mounting said stem, and a weight bar carried by the other end of said stem and adapted to receive weights which urge the stem to pivot about the pivotal mounting means to thereby control the pressure between the inner and outer edges of said surface andthe conditioning ring.

2. A lapping machine comprising an annular lap, means serving to rotate said lap, work holding means, a conditioning ring extending over the inner and outer edges of said annular lap, means for rotatably mounting said conditioning ring, said mounting means including a stem, a slot formed in said stem, a pin pivotally engaging said stem through said slot, an inwardly extending arm having the pin aflixed thereto and preventing movement of the conditioning ring with the lap, and a weight bar carried by the upper end of said stem and adapted to receive weights to thereby tend to pivot the stem about the pin to thereby control the pressure between the inner and outer edges of the lap and the conditioning ring.

3. A lapping machine comprising a frame-like structure, a vertical shaft rotatably mounted in bearings carried by said frame, a turntable carried by said shaft, means for driving said shaft and turntable, a pivot column mounted at the upper end of said shaft and extending upwardly, work holding arms mounted to said column and extending radially outward, work holding means spaced from the surface of said table and including work receiving openings, means serving to rotatably mount said work holding means, stems extending upwardly from said rotatable mounting means and through said arms, said arms including means for locking the work holding stems in a predetermined vertical position, means for accurately positioning said stems in a vertical direction, a conditioning ring extending over the inner and outer edges of the turntable, means for rotatably mounting said conditioning ring, said mounting means including a stem, means pivotally engaging said stem, and a weight bar carried by the upper end of said stem and adapted to receive weights to urge the stem to rotate about the pivot to thereby control the pressure between the conditioning ring and the inner and outer edges of said turntable.

4. A lapping machine comprising an annular lap, means serving to rotate said lap, work holding means, a conditioning ring extending over the inner and outer edges of said annular lap, means for rotatably mounting said conditioning ring, said mounting means including a stem, a slot formed in said stem, a pin pivotally engaging 'said stem through said slot, an inwardly extending arm having the pin fixed thereto and preventing movement of the conditioning ring with the lap, a weight bar carried by the upper end of said stem and adapted to receive weights to thereby tend to pivot the stem about the pin to thereby control the pressure between the inner and outer edges of the lap and conditioning ring, and a work holder rotatably carried at the other end of said stem, said work holder having a diameter which is less than the inside diameter of the conditioning n'ng whereby the same is free to rotate independently thereof and disposed above the lap surface whereby it rotates free of the same.

References Cited in the file of this patent UNITED STATES PATENTS 1,763,647 Danner June 17, 1930 2,079,076 Kranich May 4, 1937 2,541,912 Broughton Feb. 13, 1951 2,597,382 Roshong May 20, 1952 2,607,173 Garrison Aug. 19, 1952 2,772,521 Voytech Dec. 4, 1956 2,782,571 Hanson Feb. 26, 1957

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