US2171254A - Abrasive tool - Google Patents

Description

Aug. 29, 1939. L J. KAUFMAN ET AL ABRASIVE TOOL Filed June 15, 1935 g/vvvw/z/s L-J-KEm rnan E-H-E em haK 3/ W MID/0W6 Patented Aug. 29, 1939 UNITED STATES PATENT OFFICE ABRASIVE TOOL Application June 15, 1935, Serial No. 26,810

1 Claim.

This invention relates to abrasive tools, and more particularly to tools for refinishing valve seats of various contours.

In the refinishing of valve seats, at the present time, it is customary to utilize a cutting tool, or an abrasive tool, in which the abrasive-coated material is pre-formed or shaped to the tool and contour of the valve seat, or work to be finished.

Grinding or cutting tools are expensive, require accurate guides and pilots, and when dull leave the work ridged and marked, in addition to requiring highly skilled labor. In instances where abrasive tools are utilized, pre-forming of the abrasive material addsmaterially to its cost, and it is necessary to carry a great many shapes and sizes in stock, and the pre-formed abrasive cup or element tends to loosen up or Wrinkle during rotation of the tool.

The present invention has primarily for its object to overcome the foregoing objections by the provision of an exceedingly simple, inexpensive and efiicient abrasive tool adapted to utilize a normally fiat disc or sheet of flexible, abrasivecoated material, such as cloth and the like, which may be readily replaced as often as is needed at minimum expense.

Incidental to the foregoing, a more specific object resides in the provision of a tool of the foregoing character, utilizing chucks of substantially conical form, and flexible, abrasive-coated discs or sheets: adapted to be readily clamped on and conformed to the chuck and work, thus insuring a smooth, accurate finish.

A still further object of our invention is the provision of a spider having radially projecting. inclined arms adapted to engage a normally flat flexible sheet of abrasive material for forming the material on the head of the tool with folds in the material, whereby the accurate shaping of the material is insured, and whereby slipping or wrinkling of the material when the tool is in use is eliminated.

With the above and other objects in View, which will appear as the description proceeds, the invention resides in the novel construction, combination and arrangement of parts, substantially as hereinafter described and more particularly defined by the appended claim, it being understood that such changes in the precise embodiment of the herein disclosed invention may .be made as come within the scope of the claim.

In the accompanying drawing is illustrated one complete example of the physical embodiment of the present invention constructed according to the best mode so far devised for the practical ap plication of the principles thereof.

In the drawing:

Figure l is a vertical section through one preferred form of our improved tool designed for finishing valve seats of internal combustion engines and the like, a fragment of the valve seat being shown in section.

Figure 2 is a detail illustrating a flexible connection provided for the tool stem, parts being shown broken away and in section.

-Figure 3 is a bottom plan section taken on the line 3-3 .of Figure 1.

Figure 4 is a plan of the blank forming the abrasive disc utilized with our improved tool,

Referring to the drawing in detail, wherein similar reference characters designate corresponding parts throughout the several views, the

letter A generally indicates our improved tool, which embodies a solid cylindrical shank 5, having a collar 6 knurled .or otherwise secured thereon to form a shoulder. The upper end of the shank 5 is provided with threads 1 for the reception of a coupling member or nut 8, which cooperates with the collar 6 to clamp the operating head 9 thereon. The head is removable, either for replacement of a different shaped head or renewal of the abrasive disc or sheet l0, as will be hereinafter described.

The working head 9 illustrated is provided with a tapered working face of substantially forty-five degrees, and interrupted at a plurality of spaced points by radial grooves I I.

Obviously, in a head of any substantial diameter provided with a working face formed at arelatively steep angle, it is impossible to make a flat flexible disc or sheet to conform thereto without bunching, which would be detrimental to both the abrasive sheet and the valve seat. Therefore, in order to insure a snug, smooth fit of the abrasive disc or sheet over the inclined working face of the head 9, a spider I2 is provided. The spider l2 includes a flat apertured hub I3, and radially extending inclined arms M. The hub I3 of the spider I2 is slipped on the shank in engagement with the collar 6, and the radial arms M are alined and received within the grooves II in the head 9, as best shown in Figure 1.

In actual practice, it is preferred to form the spider of resilient material, in order that the arms l4 may exert a slight tension upon the folds of the disc Ill forced into the grooves II.

In grinding the valve seats of internal combustion engines and the like, accuracy is desirable, and, therefore, in work of this character the shank 5, in addition to serving to hold the head and abrasive disc I0 in assembled relation, also acts as a pilot, in that it is fitted into the usual valve stem guide l5 of the engine. Thus, the shank 5 serves to accurately aline the working face of the head with the valve seat l6.

Inasmuch as the tool A is then guided, it is desirable to provide a flexible connection between the same and the operating shank 20. Therefore, the lower end of the operating shank 20 is provided with a spherical head 2|, which fits into a recess ll formed in the coupling member or nut 8. The transverse slot 22 in the spherical head 2! receives a pin l8 carried by the coupling member or nut 8. Thus, in the event of disalinement, all relative movement between the stem 20 and the tool A is readily compensated for, and will, therefore, not aifect the accuracy of the finishing operation.

In Figure 4 the manner in which the folds occur in the abrasive disc l0, when the same is clamped to the head 9 by the spider I2, is illustrated in dotted lines. Obviously, the tightening of the coupling member or nut 8 on the stem or shank 5 will clamp the head 9, the spider I2, and the abrasive disc or sheet [0 firmly together.

Particular attention is invited to the fact that the arms i l of the spider form the folds in the abrasive disc or sheet H), and prevent the bunching, wrinkling, or slipping of the abrasive sheet or disc ill on the head.

From the foregoing description considered in conjunction with the accompanying drawing, it will be readily seen that a comparatively inexpensive and highly efficient tool has been provided, which will materially reduce the cost of grinding or refinishing valve seats, inasmuch as the same is accomplished by the use of inexpensive, thin, flat abrasive discs or sheets requiring no special shapes, and because of their relatively low costs, permitting frequent replacement.

Further, should the operator run out of discs supplied for the tools, the same can be readily formed out of ordinary abrasive cloth or paper, without the delay incident to obtaining a new supply.

A further advantage resulting from the structure is that the discs themselves can be shifted on the head or chuck 9 upon the loosening of the clamping means, so that the. unused surfaces (the folds) can be presented for use, after one portion of the discs has become worn.

Changes in details may be made without departing from the spirit or the scope of our invention, but what we claim as new is:

In a valve seat grinding tool, a rotatable body, an abrasive supporting head on one end of said body and having a side wall surface tapered at an angle corresponding substantially to the angle body and extending into said indentations and constructed and arranged to press the abrading element inwardly into said head grooves to draw and hold said element evenly and tautly upon said head, and means carried by said body and operable to move and hold said first means within said indentations and also adapted to detachably secure said first means and abrading element in place upon said head.

LEONARD J. KAUFMAN. CHARLES H. SHEMCI-IAK.

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