US2376531A - Lapping machine - Google Patents

Description

May 22, 1945. w, F. EGGER LAPPING MACHINE Fi led Nov. 11, 1943 2 Sheets-Sheet 1 INVENTOR. WALTE R EEG GER ATTORNEYS May 22, 1945. w. F. EGGER LAPPING MACHINE 2 Sheets-Sheet 2 Filed Nov. 11, 1943 V G 9 M m n A B 2 M M Patented May 22, 1945 LAPPIN G MACHINE Walter F. Egger, Rocky River, Ohio, assignor to Albert P. Schraner, Shaker Heights, Ohio, doing business as A. P. Schraner & Co.

Application November 11, 1943, Serial No. 509,850

12 Claims.

This invention relates as indicated to lapping machines and more especially to machines of the character whichare designed to lap or polish the cylindrical surfaces of rotatable workpieces such as crankshafts and the like, i. e. those portions of the crankshaft on which the main and connecting rod bearing surfaces are provided.

It is a more specific object of my invention to provide an apparatus of the character described which will effectively lap or polish those portions of said bearing surfaces which extend at right angles to the axis of the workpiece, that is, they extend in a plane substantially. normal to the axis about which the shaft is rotated.

Lapping machines of this character generally employ an abrasive coated ribbon, an intermediate portion of which is moved into engagement with the area being operated upon.

It is a further and more specific object of my larly pointed out in'the claims, the following de-- scription and the'annexed drawings setting forth in detail certain illustrative embodiments ofthe invention, these being indicative, howevenof but.

a few of the various ways in which the principle of the inventionmay beemployed.

In said annexed drawings: Fig. 1 is a side elevational view partially in sectionof one form of apparatus embodyingv the principles of my invention;

Fig. 2 is a side elevational view drawn to an enlarged scale of a portion ofthe apparatus illustrated in Fig. 1; m

- Fig. 3 is a plan view of that portion of the apparatus illustrated in Fig. "2;

Fig.4 is a transverse sectional view of the apparatus illustrated in Fig. Ltaken on a plane substantially indicated by the line 4-4;

Figs. 5 and 6 are respectively fragmentary sectional views of a portion of the apparatus as illustrated in Fig. 5 showing the several parts thereof in dilferent positions,

i Fig. 7 is aside elevational view of another form of apparatus embodying in a different environment'one of the principles of my invention;

Fig. 8 is a fragmentary side elevational view of one of the work-engaging jaws of the apparatus of Fig. 7; and

Fig. 9 is a transverse sectional view of the structure illustrated in Fig. 8, taken on a plane substantially indicated by the line 9-9.

Referring now more specifically to the drawings and more especially to Fig. 1, the apparatus here illustrated, and incorporating certain of the features of my invention, is part only of a complete lapping machine such as that illustrated in my prior Patent No. 2,121,025, issued Jan. 21, 1938. Only so much of that machine as is related to the present invention has been illustrated and will be described herein. For a description of the general operation of the machine, reference may be had to my said prior patent.

In my said prior patent the bearing surfaces of the crankshaft are engaged at diametric opposite points by jaws over which are stretched. ribbons of abrasive coated material, and such'jaws are urged into engagement with the outer cylindrical surface of the bearing areas under the influence of a fluid actuated ram l. The present invention is concerned with the provision of workengaging heads which will lap or polish the shoulders or side parts of the bearing areas, i. e.

those which extend in a plane normal to the axis of rotation of the crankshaft. Two identical heads are provided, each carried on the lower end of bell-crank levers 2, the upper ends of which levers are connected through toggle links 3 to the head 4 of the piston rod 5 of the jack I. Thus, when the piston rod is elevated, the toggle linkage just described will move the heads, generally indicated at 6, into engagement with the crankshaft, and when the piston rod 5 descends, the head 6 will be moved out of engagement with the crankshaft. The construction of the heads 6 is most clearly illustrated in Figs. ,2 to 6. Since these heads are identical, only one will be described, and similar reference characters will be employed to designate corresponding parts on the other head.

To a base member 'I there is secured, as by welding or otherwise, an upstanding member 8, and also a pin 9. Rotatably mounted on the pin 9 is a spool ID, carrying an abrasive coated ribbon ii. The upstanding member 8 is provided with slots l2 at opposite sides for the purpose of guiding the abrasive coated ribbon which is passed therethrough. V V v 7 Likewise secured to the base 1 is an upstanding wedge-shaped part l3, the uniform cross-section of which is most clearly apparent from an inspection of Figs. 4 to 6. The member i3 is provided with a slot on its outer vertical face into which extends the lower end of the bell-crank 2. Aligned openings extending transversely,

through the member I3 and the end of the arm 2 receive a pin I4 by which the member I3 is removably attached to the arm 2.

Mounted on opposite sides of the member l3 are cam members l5 and IS, the uniform crosssection of which will be apparent from Figs. 4 and 6, and the lateral configuration of which will be apparent from Fig. 2. The inner faces of the members l5 and I6 are arcuate and of a diameter slightly greater than the diameter of thebear ing surface on which the apparatus is designed to operate. I

The upper and lower corners of each of members l5 and iii are provided with identical removable projections l'l, each of which is provided with an opening [8 to receive the terminal portion of a cross-shaft l9. On the cross-shafts l9 are mounted rollers 20, the 'outer surfaces of which lie on an are having a diameter slightly less than the arc of the inner faces of the members l5 and l'6., The are on which the rollers 20 lie should have .a radius equal to the radius of the bearing surface being operated upon. The shafts I!) are securedatone end in either the member, [5 or IE, andat their opposite ends slidable in the opening embracing the same, so that the members and I6 may move toward and away from each other.

On the upper and lower faces of each of members I5 and l6 are projecting pins 2I, and to such pins are secured the opposite ends of springs 22 biased so as to resiliently urge the members 15 and I6 toward each other; against the. inclined opposedfacesof the central member l3.

The members [5 and [6 are provided with slots 23, the vertical dimension of which is equal to the, diameter of thepinl l, with'the horizontal dimension substantially greaterthan such diameter in orderthat, as viewed in Figs. 4 to 6, relative movement betweenthe members [5 and I6 and central'member lfimay occur.

Intermediately or their ends, the members l5 and l ar provid d ith attac ed pads 24 of oil -resistant synthetic rubber. The inner face ofthe pads 24, i. e those faces directed toward the cylindrical bearing surface, have a radius sufficiently greater than the radius of such bean ing surfaces sothat the abrasiv coated ribbon passing thereover will not have contact with such cylindrical surfaces when the rollers are in engagement with such cylindrical surfaces.

The function and operation of the apparatus just illustrated is briefly as follows:

With the heads mounted on the ends of the arms 2 and out-ofengagement with the bearin surface on the crankshaft, the piston rod 5 is elevated causing suchheads through the toggle linkage-,prgeviously described, to move ,into engagement with the bearing surface. With the heads out of engagement with the bearing surface, the springs ;22, urging the members l5 and I6 toward "each Qther, will cause such members and associated part'l3 to occupythe relationship illustrated in Fig. 5. 'I-Io wever, when the toggle arm's'Z are'mov'ed toward thebearing, they, acting through the wedge-shaped members I3, will cause the membersli'and ffi to spread apart, as illustrated in Fig. 6, until their opposite faces, 1. e., those carrying the pads 24, m v i o enra ement with the radial s amans 25 on opposite sides of the cylindrical bearia jeieastamens.

The pads 24 will hold the abrasive coated ribbon against these radial shoulders, and during the subsequent rotation of the crankshaft, such radial shoulders, as well as the fillet joining the radial shoulders and the cylindrical surface, will be lapped and polished.

At the conclusion of the operation, the piston rod 5 will be lowered, separating the heads from the shaft, whereupon the springs will move the members l5 and I6 toward each other, and the apparatusmay then be swung out of engagement with the crankshaft.

In any lapping operation, such as that just described, and such as is adapted to be performed by the apparatus of my aforementioned prior patent, some means must be provided for the purpose ofpreventing shifting between the abrasive coated ribbon and the lapping arm or head by which the same is moved into engagement with the work.

It has been common practice up to the time of my invention to coat the machine part which engages the back face of the abrasive ribbon with a relative coarse abrasive material so as to prevent relative movement between the ribbon and the part which forces the ribbon into engagement with the work. Heretofore, no other means has been found satisfactory for this purpose. In practice, however, these abrasive coated ribbons have a tendency to tear or become misaligned, and when this happens the part carrying the coarse abrasive comes in contact with the bearing surface to be lapped, scoring, and in many times, ruining the entire crankshaft.

The employmentof oil-resistant synthetic rubber as the material for the pad 24 obviates this difficulty, I have found that commercially available synthetic rubber, sold under the name Neoprene, and other products similar thereto, is entirely satisfactory for this purpose.

- This expedientof holding in place and resiliently backing up the abrasive coated ribbon may be employed in environments other than the specific embodiment of my invention thus far described.

For example, in an apparatus of the character illustratedin my said prior patent, and as illustrated in Fig. 7, the invention will I, be found of particular utility. In this type' of lapping machine, the cylindrical surfaces of the bearing to be lapped are engaged at diametrically opposite areas by means of jaws 21, the inner faces of which are arcuate on a radius substantially equal to the radius of the cylindrical bearing surface i la'pbed.

In 'accordanc'e' with th rior practice, it has been conventional to provide on'these inner faces of the blocks 21 a shee'tf'of coarse sand paper holding the abrasive coated ribbon :28 from slipping relatively to the blocks 21 during the lapping operation. as previously indicated, should the abrasive coated ribbon 28;tear, then-the coarse sand paper col'nes'in contact with the-bearing surface, many times so-scoring the same as to require rejection of the entire crankshaft.

This problem I have solved by providing on=the inner faces of the blocks -21 a layer 29 of synthetic rubber, and inthe preferred embodiment of my invention, the-resilient pad-thus provided has a series of spaced grooves 30 formed'therein, such grooves extending substantially parallel -to the axis of relativ rgtation -bet ween'the-bearing and the blocks 21. This expedient of grooving the rubber pad-is of particular importance in th'a't'it permits'intermediate spaced portions of,

the ribbon 28 to become wedged in the grooves, thus insuring against relative movement between theribbon and the padduring the lapping opera--- tion.

Similarly, if'the extent of the pads 24 of Fig. 2

are considerable, then they too should preferably be provided with grooves which extend transversely of the direction of relative movement between the part being lapped and the abrasive coated ribbon.

I have thus provided an improved lappingmachine which'accomplishes all of the objects aforesaid, and which in particular is effective to polish or lap those surfacesof crankshafts which have heretofore been finished entirely by hand.- v

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed. 1

I therefore particularly point out and distinctly claim as my invention:

1. In apparatus for lapping a work piece of the general form of a; crank shaft with crank-pin and adjoining shoulder surfaces, th combination of a carrier part, primary means on said carrier partjengageable with the work in an area adjacent said shoulder surface, secondary means on said carrier engageable with said shoulder surface and movable relatively to said carrier in a direction substantially parallel to the axis of the crank-pin, and means for effecting said last named movement.

2. In apparatus for lapping a work piece of the general form of a crank shaft with crank-pin and adjoining shoulder surfaces, the combination of a carrier part, primary means on said carrier part engageable with the work in an area adjacent said shoulder surface, secondary means on said carrier engageable with said shoulder surfaces and movable relatively to said carrier in a direction substantially parallel to the axis of the crank-pin, means intermediately of said primary and secondary means whereby pressure of the former against said work effects said last named movement.

3. In apparatus for lapping a work piece of the general form of a crank-shaft with crank-pin and adjoining shoulder surfaces, the combination of a carrier part, primary means on said carrier part engageable with the work in an area adjacent said shoulder surface and responsive to such engagement movable relatively to said carrier in a plane substantially normal to the axis of the crank-pin, secondary means on said carrier engageable with said shoulder surface and movable relatively to said carrier in a direction substantially parallel to the axis of the crank-pin, means intermediately of said primary and secondary means whereby relative movement between the former and said carrier effects relative movement between said secondary means and said carrier to cause said secondary means to move into engagement with said shoulder surfaces.

4. In apparatus for lapping a work piece of the general form of a crank-shaft with crank-pin and adjoining shoulder surfaces, the combination of a carrier part, primary means on said carrier part engageable with-the work in an area adjacent said shoulder surface and responsive to such engagement movable relatively to said carrier in a plane substantially normal to the axis of the crank-pin, secondary means on said carrier engageable with said shoulder surface and movable relatively to said carrier in a direction substantially parallelto the axis of the crank-pin, means intermediately of said primary and secondary means whereby relative movement between the former and said carrier effects relative movement between said secondary means and said carrier to cause said secondary means to move into engagement with said shoulder surface, and work engaging pads of resilient material on those faces of said secondary means which are opposed to said shoulder surfaces, said pads provided with grooves extending across the face thereof in a direction substantially parallel to the axis of the crank-pin,

5. In apparatus for lapping spaced opposed shoulder surfaces on a rotatable work piece of the general form of shoulder surfaces adjacent a crank-piece, the combination of a carrier part, primary means on said carrier part engageable with th work in an area intermediately of said shoulder surfaces, secondary means on said carrier engageable with said shoulder surfaces and movable relatively to said carrier in a direction substantially parallel to the axis of the crank-pin, and means for effecting said last named movement. i

6. In apparatus for lapping spaced opposed shoulder surfaces on a rotatable work piece of the general form of shoulder surfaces adjacenta crank-piece, the combination of a carrier part, primary means on said carrier part engageable with the work in an area intermediately of said shoulder surfaces, secondary means on said carrier engageable with said shoulder surfaces and movable relatively to said carrier in a direction substantially parallel to the axis of the crank-pin,

means intermediately of said primary and secondary means whereby pressure of the former against said work effects said last named movement. 7

'7. In apparatus for lapping spaced opposed shoulder surfaces on a rotatable work piece of the general form of shoulder surfaces adjacent a crank piece, the combination of a carrier part, primary means on said carrier part engageable with the work in an area intermediately of said shoulder surfaces and responsive to such engagement movable relatively to said carrier in a plane substantially normal to the axis of the crankpin, secondary means on said carrier engageable with said shoulder surfaces and movable relatively to said carrier in a direction substantially parallel to the axis of the crank-pin, means intermediately of said primary and secondary means whereby relative movement between the former and said carrier effects relative movement between said secondary means and said carrier to cause said secondary means to move into engagement with said shoulder surfaces.

8. In apparatus for lapping spaced opposed shoulder surfaces on a rotatable work piece of the general form of shoulder surfaces adjacent a crank-piece, the combination of a carrier part, primary means on said carrier part engageable with the work in an area intermediately of said shoulder surfaces and responsive to such engagement movable relatively to said carrier in a plane substantially normal to the axis of the crankpin, secondary means on said carrier engageable with said shoulder surfaces and movable relatively to said carrier in a direction substantially parallel to the axis of the crank-pin, means intermediately of said primary and secondary means whereby relative movement between the former and said carrier eifects relative movement between said secondary means and said carrier to cause said secondary means to move into engage-merit with said shoulder surfaces, and work enga ing pads of resilient material on those faces of said secondary means which are opposed to said shoulder surfaces. v

9. In apparatus for lapping spaced opposed shoulder surfaces on a rotatable work piece of the general form of shoulder surfaces adjacent a crank-piece, the combination of a. carrier part, primary means on said carrier part engageable with the work in an area intermediately of said shoulder surfaces and responsive to such engagement movable relatively to said carrier in a plane substantially normal to the axis of the crankpin, secondary means on said carrier engageable with said shoulder surfaces and movable relatively to said carrier in a direction substantially parallel to the axis of the crank-pin, means intermediatelv of said primary and secondary means whereby relative movement between the former and said carrier effects relative movement between said secondary means and said carrier to cause said secondary means to move into engagement with said shoulder. surfaces, and work engaging pads of resilient material on those faces of said secondary means which are opposed to said shoulder surfaces, said pads provided with grooves extending across the face thereof in a direction substantially parallel to the axis of the crank-pin.

ed ribbon into engagement with a substantially I cylindrical surface on a rotating work piece, of

a pad of oil-resistant synthetic rubber substituteon said pillow arranged to engage the back face of ribbon, said pad provided with grooves extending across the ribbon-engaging face thereof in a direction angularly related to the plane of relative rotation between said pillow and the work iece.

12. In apparatus for lapping a work piece of general form of a crank-shaft with crank-pin and adjoining shoulder surfaces, an arcuate pillow adapted to maintain an intermediate portion of an abrasive ribbon in engagement with a crank-pin surface, and small rollers mounted on the upper and lower corners thereof, the are on which the rollers lie having a radius substantially equal to the radius of the crank-shaft.

WALTER F. EGGER.

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