US868860A - Grinding balls. - Google Patents

Description

PATENTED OCT. 22, 1907.

E. G. HOFFMANN. GR'INDING BALLS.

APPLIGATION FILED HAY s. 1907.

/NVENTH 477-0 NEYS W/'TNESSES f PATENT oEEIoE.

ERNST GUSTAV HOFFMANN, F NEW ROCHELLE, NEW YORK.

GRINDING BALLS.

Specification of Letters Patent. L'

Patented oct. '22, 1907.

Application filed May 6, 1907. Serial No. 372,078.

To all whom it may concern:

Be it known that I, ERNsT Gus'rav HOFFMANN, a citizen of the United States, residing inthe city of New Rochelle, in the State oi New York, have invented certain new and useful Improvements-in Grinding Balls, of which the following is a specification, reference being had to the accompanying drawing, forming a part hereof.

The grinding of metal balls for ball bearings and other purposes for which accuracy, uniformity and high finish are desirable, is commonly effected in a oil. chines is not tHe same as the peripheral speed of the machinevrhich comprises two disk-like' plates of metal, relatively rotatable and pressed yieldingly, one toward the other, concentric grooves being formed in the adjacent faces of the plates or in the face of one 4of them in whichthe ballsare received` together with an abrasive powder, usually emery powder, mixed with The peripheral speed of the balls in such ma- `number ofv scratches whichare sometimes visible to ,the naked eye as a sort of cloudiness or dullness upon the surface of the ball and are always plainly apparent when the ball is examined with' a microscope 0fmoderate power. The balls finished fin this manner thereiore leave something to be desired in` the way of smoothness and by the present invention it has-been discovered that a much greater approach to perfect smooth-' ness of surface, as well as almost mathematically perfeet sphericity and accuracy of the vballs can be secured by dispensing altogether with the use oi loose abrasive material and by carrying on the grinding between two disks or plates; relatively rotatable and o e or the other provided with concentric grooves as before, whileone of such disks or plates is itself composed of abrasive material. Especially good results are attained if such particles of abrasive material as may be loosened fromthe plateor disk as it wears away are immediately removed',"as by washing them out with a constant and ample flow of a suitable liquid.

The inventionwill be more fully explained hereinafter with reference to the-accompanying'drawing in whichl'iis represented so much of a grinding machine stood, and in which-- f The' whole surface VFigure 1 is a view in side elevation, partly broken out, of a portion of such a machine, and Fig. 2 is atop view oi the same. l

` In the particular form of mechanism which is chosen for illustration of the nature of the invention astationary disk A, preferably of metal and having in its working face a s'eries of concentric grooves a, is mounted upon a-stationary shaft B, being held from rotation thereon and also from longitudinal movement by any suitable means, such as a pinb passing through the hub of the grinding disk or plate A and the shaft and. removable to permit the disk or plate to be moved hack upon the shaft when necessary.

A rotating disk or plate (l, made of any suitable abrasive material, such as corundurn, for example, is mounted to rotate upon the shaft B, being provided for this purpose, in the machine shown, with a suitable -wheel or belt pulley D. It is pressed toward the plate or 4disk A l y any suitable means, as a stiff spiral spring E surrounding the shaft B and abutting against an adjustable nut e. The pl'ate or disk O may or may not be provided, when new, with concentric grooves in its working face, which correspond to the grooves a in the working face of the disk or plate A, but such grooves are naturallyformed therein as the use of the machine continues. I

The balls to be ground, which are shown in place in Fig. l, may b e introduced and removed and interchanged through slots in the disk A and by means of a table G`in spiral form, all as fully explained in Letters Patent of the United States No. 803,164, dated October 3l, 1995, or by any other suitable means. The operation of the machine shown in the drawing is in general. the same as that of the machine described -in said Letters Patent, but no emery powder or other loose abrasive material is supplied to the machine, the abrasive action of the disk O being alone relied upon. If this disk is made of suitable material, it will 4slowly wear away in an impalpable powder, but to prevent any scratching of the balls by particles which' may be loosened from the disk it is desirable that they l be removed immediately. If `the grinding should be done dry,4 such loose particles would be quickly thrown' out or might be blown out by a .blast of air suitably directed. The grinding, however, is .preferoil Hows through a pipe h to a centrifugal pump I by Which it is returned t'o the grinding disks through a piper by which the oil or other liquid is distributed upon the table G from which it passes With the balls through the disk A to the grinding surfaces.- By s'uch means the particles of metal and of abrasive material are immediately removed from the grinding surfaces and the scratching of the balls thereby is Wholly obviated. V

From the fact that the disk A is provided with a series of concentric grooves it Will be apparent that the balls do not partake of any radical movement `across the disk C of abrasive material during the grinding process, from which it follows that in my process the balls always travel in a path or paths concentric with the axis of the rotating disk during the grinding operation. 'This will result in` slight grooves being formed in the abrasive diskl when in use, as above pointed out, whereby the area of contact between the abrasive disk and the balls is increased and a better' grinding action secured. 1

While the machine herein shown is Well adapted for 'carrying out the invention, it will, nevertheless7 be understood that thelinvention is not restricted to any particular form or type of machine and that the mechseaseo anism shown and described herein canr be variedhas may be found desirable to meet the necessities of dil ferent uses.

I claim as my invention:

l. The improvement in the method of grinding vballs which consists in 4grinding them between relatively rotating disks, while they travel in a path concentric with the axis of rotation one of said disks being formed of abrasive material.

2. The improvement in the method of grinding` balls which consists in grinding them between relatively rotating disks, While they travel in a path concentric with the axis of rotation, one of said disks being formed of abrasive material, and in immediately removing the loose particles of abrasive material.

3.' lhe improvement in the method of grinding balls which consists in grinding them between relatively rotating' disks, while they travel in a seriesy of paths each corr., centriewith the axis ofmrotation one of said disks being formed of abrasive material, and in constantly washingY out the loose abrasive material by means of a suitable liquid.

Api-i1, A. D., 1907;`

ERNST GUSTAV HOFFMANN.

Signed in the presence of Ammosn L. OSHEA, ELLA J. KRUGER.

This specication signed and Ywitnessed this 26th day of

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