US2592071A - Abrading machine - Google Patents

Description

April 1952 G. A. RUSSELL 2,592,071

ABRADING MACHINE Filed Feb. 25, 1949 2 SHEETS-SHEET l i i l BY fwd H75 A TTOQ/VEW April 8, 1952 G. A. RUSSELL 2,592,071

ABRADING MACHINE 2 SHEETSSHEET 2 Filed Feb. 25, 1949 In v y FIG. 6

//v VEA/TOB G lLBEBT A Q USSELL H/S ATTORNEY Patented Apr. 8, 1952 2,592,071 ABRADING MACHINE Gilbert A. Russell, Granford, N. J., assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application February 25, 1949, Serial No. 78,255

2 Claims.

This invention relates to abrading machines and comprises all of the features of novelty herein disclosed. An object of the invention is to provide a simple and efficient machine for producing nicely finished surfaces on the spherical interior zones of hollow work pieces such as roller bearing race rings. Another object'is to produce an improved machine for grinding a spherical zone on the interior of a race ring or the like and honing the surface at one set-up by a single abrasive wheel. Another object is to provide an improved machine for grinding and honing a spherical zone on hollow work pieces without changing the relative positions of the work pieces and the abrasive wheel as the wheel wears down.

To these ends and also to improve generally upon machines of this character, the invention consists in the various matters hereinafter described and claimed. In the drawings,

Fig. 1 is a plan view with a portion of the work head casing broken away; 1

Fig. 2 is a front view;

Fig. 3 is an end view and partial section of an overrunning clutch in Fig. 1;

Fig. 4 is a front view of the work supporting and rotating means;

Fig. 5 is 9, side view of Fig. 7 with the work in section;

Fig. 6 is a front view of Fig. 5;

Fig. '7 is a side view of Fig. 5 looking in the direction of wheel feed with the wheel spindle in section; and

Figs. 8 and 9 are diagrammatic views.

The illustrated work piece W is the outer race ring of a roller bearing whose interior spherical surface is to be ground and honed. The work head with its work supporting and gauging mechanism is similar to that disclosed in patent to Cramer 2,330,809, especially its Figs. 14 and 19, and need not be described in detail. It sufiices to state that the back face of the work piece engages a backing-up ring 2 while the work is frictionally rotated by a driven regulating wheel 4, the work being supported by a supporting idler wheel 6 and pressed against the regulating wheel by a swinging idler wheel 8. The foregoing parts are enclosed in a casing I having suitable openings to insert and remove the work as well as to provide for access of a grinding wheel G to the interior surface of the work. This work head can be swivelled around a vertical axis to a selected angular position where it is fixed although it may also oscillate if desired.

The grinding wheel G is rotated by a spindle l2 journalled in a head I3, the spindle having a pulley driven by a belt l4 from a high speed motor IS. A low speed motor l8 having a pulley drives a belt 20 extending around a pulley 22 which is made integral with or attached to the outer member 24 of an overrunning clutch. The illustrated clutch includes a series of sprags or tiltable grippers 26 whose opposite sides are recessed to receive garter springs 21. The grippers are interposed between the outer clutch member 24 and an inner clutch member 28 which is keyed to the shaft of motor [6. When the high speed motor I6 is running the clutch overruns and when this motor is shut off, its shaft is driven by motor I 8 through the clutch. The two motors are supported by a slide 30 adjustable by a screw 32 on a cross feed slide 34 which is fed rearwardly by a feed screw 36. The wheel spindle I2 is parallel to the slide 34. A main slide 38 supports the slide 34 and is given one reciprocation at each cycle of grinding substantially as in Van Norman Patent 2,149,409 and moves the grinding wheel laterally into the work. The feed screw 36 may be ratchet operated as in the patent and moves the grinding wheel axially against the work surface.

When the machine is grinding, the grinding wheel spindle [2 has its axis definitely located to intersect the point C which represents the center of curvature of the spherical zone S on the interior surface of the work piece W. The grinding wheel G is a cupped wheel with a cylindrical exterior and a cylindrical interior and terminates in a spherical rim or band 40 which is selfdressing by contact with the work surface. The diameter and area of this surface remain constant as the wheel wears down. The shaded areas A and B in Fig. '7 indicate the two areas where the wheel engages the work. Initially the wheel is driven at high or grinding speed by the motor l6 and the work speed is comparatively slow.

Viewing diagrammatic Figure 8 where the work is shown developed, the particles of the grinding wheel will traverse the work on the area A of Fig. 7 and produce marks about as indicated by the lines beginning at 42 and slanting downwardly to the left. The nearly opposite portion of the wheel at the area B of Fig. 7 produces marks about as indicated by the lines beginning at 44 and slanting upwardly to the left. Thus a crosshatch pattern is produced as the work rotates. When the motor [6 is shut off, the motor l8 drives the wheel at a honing speed which is low compared to the speed of the work and a fine cross hatch pattern similar to Fig. 9 is produced. This pattern is not affected by wear of the wheel since the spherical band 40 of the cupped wheel remains of constant diameter as the wheel wears to its bottom. Also, this band always maintains the same relation to all work pieces of a given size and all those pieces will be finished alike. The center of curvature C lies in the axes of both work and wheel. These axes may be made to intersect at various angles within certain limits and this can be made to change the cross hatch pattern somewhat.

As indicated in Fig. 9, the honing marks, due to the low surface speed of the wheel as compared to the speed of the work, extend much more nearly circumferentially of the spherical zone S than crosswise thereof and this very desirable effect is considerably increased because the axis of the wheel, although it intersects the work axis and so always lies in a radius of the spherical zone, meets the spherical zone well to one side of the central plane of the spherical zone and preferably close to one end of that zone. This construction also provides for the use of a long, deep cup wheel with a sturdy driving spindle and mounting without interference with the end of the work piece. When the honing marks run more nearly circumferentially than crosswise, the completed roller bearing runs considerably cooler which may be due to better retention of lubricant.

The machine may be entirely automatic. In a complete cycle with the slides retracted, a work piece travels down to operative position in. the work head as in the Cramer patent and the slides advance the wheel into the work and then against it. The wheel is fed along its axis until the gauge or sizing device controls a slower cross feed. The gauge later controls stopping while the grinding wheel is slowed down to about 300 R. P. M. The wheel and the work preferably have the same direction of rotation.

I claim:

1. In a machine for grinding and honing an angular contact spherical zone on the interior of a hollow race ring by a single abrading wheel at one set-up, means for rotating the race ring on its axis, an abrading wheel of deep cup shape having its axis intersecting the race ring axis at a point outside of the race ring, means for initially rotating the abrading wheel at a much greater surface speed than the race ring, means for thereafter reducing the speed of the wheel substantially below the speed of the race ring to cause the same wheel to abrade the spherical zone in a cross-hatch pattern wherein the marks extend more nearly circumferentially of the spherical zone than transversely thereof, and the wheel axis intersecting the spherical zone at a point nearer to one end than to the other to increase the circumferential extent of the marks.

2. In a machine for grinding and honing a spherical zone on the interior of a hollow work piece by a, single grinding wheel at one set-up, means for rotating the work on its axis, a cupshaped grinding wheel having its axis passing through the center of curvature of the spherical zone at a point outside of the work piece and located at an acute angle to the work axis, means for initially rotating the grinding. wheel at grinding speed, and means for thereafter reducing the surface speed of the wheel substantially below the surface speed of the work to make the same wheel hone the work in a crosshatch pattern wherein the honing marks extend more nearly circumferentially of the spherical surface than crosswise thereof.

GILBERT A. RUSSELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,352,790 'Danielsson Sept. 14,.1920 1,401,832 Taylor Dec. 27, 1921 2,033,395 Peaslee Mar. 10,1936 2,127,210 Dunbar Aug. 16, 1938 FOREIGN PATENTS Number Country Date 57,571 Sweden May 4, 1920

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