US2345177A - Method and apparatus for grinding ball seats in steel articles - Google Patents

Description

March 28, 1944. o. R. BRINEY, JR

METHOD AND APPARATUS FOR GRINDING BALL SEATS IN STEEL ARTICLES Filed May 21, 1942 l I B ISHHII I A INVENTOR. 077/5 7?. BIEM/EY 7?- FIGIG. zrf' TM I ATTO/PNE'YS Patented Mar. 28, 1944 METHOD AND APPARATUS FOR GRINDING.

BALL SEATS IN STEEL ARTICLES OttisR. Briney, Jr., Pontiac, Mich.

Application May 21, 1942, Serial No. 443,868

2 Claims.

This invention relates to an improved method of grinding or honing ball seats in metal articles and further to the apparatus employed in the practice of such method.

One of the objects of the invention is to grind a spherical recess in a machine part by placing a dry, abrasive laden ball therein, then moving the ball under pressure over the surface of the recess in an ever changing path.

Another object of the invention is to provide a ball which is formed from a material of a character capable of supporting an abrasive yet capable of repeated use without appreciable loss of size and form. Exemplary of such material is a high carbon chrome alloy steel carburized but not quenched or a steel ball of a similar alloy which is hardened and ground, then spheroidized or annealed.

Another, object of the invention is to charge or load the surface, of; a honing ball with an abrasive by either violently tumbling av metal sphere .in a receptacle containing an abrasive flour or diamond powder or rolling a ball, under pressure between fiat horizontal steel plates having a coating of a dry abrasiveflour thereon.

A further object of the invention is to provide a platen for supporting and effecting the movement of the balls relative to, the work during the honing operation. To this end the invention contemplates a pad formed from a material which offers a higher frictional surface. resistance than that of the work, a material which possesses suificient resiliency to. compensate for such irregularities in height as may occur in mounting a number of work pieces in the holder and a material which is capable of being impregnated with the abrasive worn from the balls as they are agitated in the work. A sheet of bonded comminuted cork has been found, in practice, to provide such of the foregoing prerequisites as are essential to the successful exercise of the improved honing method. Rubber or hard felt pads may also be used if desired.

Other objects and advantages more or less ancillary to the foregoing and the manner in which all the various objects are realized will appear in the following description, which considered in connection with the accompanying drawing, sets forth the preferred embodiment of the invention.

In the drawing which shows, for illustrative purpose only, one of the forms of apparatus that may be used in carrying out the method:

Fig. 1 is an elevational view of a fragmentary portion of a drill press showing the work holder mounted thereon;

Fig. 2 is a plan view of the work holder illustrated in Fig. 1;

Fig. 3 is a vertical sectional view throughv a portion of the work holder, the section being taken on a plane indicated by the line 3-3 in Fig. 2;

Fig. 4 is a sectional view througha work piec which is typical of the type, of product that can be finished by the improved method;

Fig. 5 is an elevational view, shown partially in section, of the. tumbling machine used in charging the honing balls; and

Fig. 6 is an elevational. view of an alternate form of mechanism used, in charging the honing balls.

Referring first to Fig. 4, thework piece chosen for the purpose of illustration comprises. a carburized semi-finished steel body 10, machined with a reamed ball seat ll therein. End cutting tools, such as rose reamers despite the speeds and feeds employed in the use thereof are apt to score the work and leave concentric grooves and ribs which obviously are subject to abnormal wear. Moreover, the contour of a recess is seldom spherical due to deformation of the Work in hardening and the tendency of the tool or work to runf during machining operations.

As contemplated herein such irregularities in aball seat are abradedtherefrom by rolling a honing element in an ever changing path over the surface of the ball seat and in addition by simultaneously moving the work in such a manner as to cause the ball to spin or twist within the recess. 7

In production the method of abraiding the ball seats is carried out by loading a plurality of work pieces ID in a holder or chuck l2; placing a honing or grinding ball l3 in each recess, engaging the balls with a surface such as the cork pad l4 illustrated in Figs. 1 and 3, then moving the chuck relative to the pad under sufficient pressure to effect a rotative movement of the balls. The chuck preferably comprises a metal disc drilled or recessed to support the work with the ball seat portions thereof protruding from the face of the chuck in equidistant relation to each other.

In contradistinction to a lapping operation which comprehends the use of a fiuidic mixture of oil and emery and a porous or ductile lapping tool, the present invention contemplates a dry grinding process effected through the medium by a tumbling machine comprising generallyva rotatively driven shaft l5 (Fig. 5) having a spider keyed thereon which supports a plurality of cups 5 providedwith removable caps or cover plates H. The cups I6 are partially filled with .the balls I 3 and the abrasive, sufficient space being left therein to permit the charge to fall against the end walls and sides of the cup during rotation and thus produce a violent pounding and rubbing action between the balls and abrasive.-

An alternate method of charging the balls may be eii'ected by covering a flat steel plate such as shown in Fig. 6 with an abrasive floun placing one or' more balls thereon, then rotating under pressure a' second steel plate thereover;

After the chuck I2 is loaded with the work pieces and a honing ball is placed in each recess therein the chuck is inverted and placed upon the pad 14 with theballs engaged "therewith. As shown in' Fig. 1, the pad is mounted upon the table I8 01' a'drillp'ress, the'spindle Hi thereof being provided with a crank arm having a pin 2| therein adapted for engagement within a recess 22 formed in the center ofthe chuck l2. It will be understood that the drill press shown herein is used merely in an illustrative sense and that numerous other-machines or mechanism may be employed to drivethe chuck or pad without departing from the scope or spirit of the invention. The circumferential edge of th chuck is drilled for the reception of a rod 24 which is designed to engage the column 25 of the machine and effect the oscillation of the chuck during its orbital movement over the pad M; The

rod is preferably constructed for detachable connection with the chuck inorder to accommodate the removal thereof during loading. If desired the free end of the rod maybe provided witha contractile spring 26 mounted to maintain the rod in intimate relation with thecolurnn 25.

During the operation of the machine rotation of the'balls within'their seats is effected by movement of the chuck by the traction ofiered by the pad and by the weight and driving forces imposed upon the balls. In addition to the rotative movement of the balls the path or direction of translation and the rotative speed thereof will change as the chuck is oscillated about its axis while moving in th path described by the movement of the pin 2|. The tortuous paths described by the workpieces will bring the balls therein into contact with the entire surface of the respective recesses and will, moreover, cause each ball to roll in directions transaxial to such concentric grooves and ribs as may have been formed by the reamer or cutting tool during the initial machining operation of the ball seats. I

In practice it has been found that by pressure rolling or pounding a fine abrasive flour into the surface of a steel bal1 a dry honing element can be produced which may be used over and over again before it has to ,be discarded for loss of sizeor form.

Although the foregoing'description is" necessarily of a detailed character, inorder that the inventionmay be completely set forth,- it is to be 'understood'that the specific terminology is not intended to be restrictve or confiningyand that various rearrangements of parts and modifications of detail may b'e'resorted to without departing from the scope or spirit of the-invention 'as herein claimed. r

1. Mechanism for polishing bal1 seats in metal work pieces comprising,-a stationary table a'pa'd thereon, a holder-for a pluralityof work-pieces, abrasive laden balls in the ball seats in the'work pieces in said holder, engaged with said pad and constituting the support for the holder, a rota tively driven crank pivotally connected with said -holder,a stop adjacent said table and arocl on said holder yieldably engaged with said stop for oscillating said holder about its pivotal-connection with said crank. a

2. Mechanism for polishing a ball seatlin-a metal work piece comprising, a stationary table, a work piece holder superjacent thereto, an abrasive laden ball intermediate the table and the ball seat in a workpiece in said holder a rotatively driven crank loosely connected with said holder and means for. moving said holder in a substantially oval..path. H v. i 1

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