US2809478A - Grinding apparatus - Google Patents

Description

Oct. 15, 1957 H. D. LEWIS GRINDING APPARATUS Filed May 9, 1956 INVENTOR. HOMER D. LEWIS Linited States Patent GRINDING APPARATUS Homer D. Lewis, El Cajon, Calif.

Application May 9, 1956, Serial No. 583,887

3 Claims. (Cl. 51206) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a new and novel grinding apparatus and more particularly to a grinding apparatus wherein a grinding wheel is provided with a pair of diametrically opposite arcuate working surfaces which are connected by peripheral surfaces positioned radially inward of the working surfaces.

The present invention is particularly adapted for use in high speed grinding operations with metal workpieces. Prior art grinding wheels are provided with a continuous circular peripheral grinding or working surface which is necessarily in contact with the work continuously during grinding operations. Such continuous engagement between the grinding wheel and the workpiece is disadvantageous since relatively high temperatures are created tending to burn or distort the workpiece and shorten the life of the grinding wheel. When such prior art grinding wheels are utilized, the point of contact between the grinding wheel and the workpiece is not readily visible thereby hampering the operator since he is unable to observe his progress during the grinding operation. In addition, the construction of prior art grinding wheels causes the material which is ground off of a workpiece to build-up on the grinding wheel and consequently the grinding wheel must be cleaned at frequent intervals.

The present invention utilizes an arrangement wherein the working surfaces of the grinding wheel are in engagement with the workpiece approximately half of the time during the grinding operation whereby the workpiece and the grinding wheel are each allowed to cool slightly between successive periods of contact between the working surfaces of the grinding wheel and the workpiece. In this manner, the tendency to burn the workpiece is reduced and the life of the grinding wheel is substantially increased. The novel grinding wheel according to the present invention is provided with peripheral surfaces which are radially inward of the working surfaces thereof, and accordingly the point of contact between the grinding wheel and the workpiece is readily visible during operation of the device. Furthermore, the construction of the invention device is self-cleaning, thereby preventing the building-up of ground material on the grinding wheel and substantially eliminating the necessity of cleaning thereof.

An object of the present invention is to provide a new and novel grinding apparatus wherein the temperatures generated in the workpiece and the grinding wheel are reduced to a minimum.

Another object'is the provision of a grinding apparatus wherein the point of contact between the grinding wheel and the workpiece is readily visible at all times.

A further object of the invention is to provide a grinding apparatus wherein the necessity for cleaning thereof is substantially eliminated.

Yet another object is to provide a grinding apparatus which is simple and inexpensive in construction, yet which is sturdy and reliable in operation.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

Fig. 1 is an elevation of a preferred embodiment of the invention; and

Fig. 2 is a plan view of the device shown in Fig. 1.

Referring now to the drawing wherein like parts are designated by similar reference characters, there is shown a flattened body member or grinding wheel 10 formed of the usual molded grinding material. An opening 11 is provided in the central portion of the body member and is adapted to receive a suitable spindle (not shown) to which the body member is fixed for rotation about axis 12 during operation. Arcuate working surfaces 13 and 14 are formed at diametrically opposite portions of the body member and these working surfaces coincide with arcs of a circle indicated by phantom line 15, the center of which is a point along axis 12.

The corresponding ends of working surfaces 13 and 14 are connected by diametrically opposite flat peripheral surfaces 16 and 17. The essence of the present invention lies in the fact that the connecting peripheral surfaces 16 and 17 are disposed radially inward of working surfaces 13 and 14 with respect to axis 12 which passes through the center of body member 10. It is evident that surfaces 16 and 17 may be formed slightly concave or slightly convex, but a fiat surface is considered preferable since the weight of the grinding wheel is reduced to a minimum and yet the structural strength of the wheel is maintained at a maximum.

It is obvious that each pair of opposite surfaces 13, 14 and 16, 17 respectively must be substantially identical in configuration and disposed diametrically opposite one another in order to preserve proper balance of the grinding wheel. It should also be noted that peripheral surfaces 16 and 17 are positioned as close to the center of the grinding wheel as is feasible while at the same time ensuring suflicient structural strength such that there is no danger of the wheel being damaged during operation. Surfaces 16 and 17 as shown in Fig. 1 are chords of circle 15 which are subtended by an angle 0 of degrees whereby these surfaces comprise approximately one-half of the peripheral surface of the grinding wheel. These proportions have proven to be highly satisfactory when utilized with a composition grinding wheel of three inches in diameter and inch in thickness with a central circular opening having a diameter of inch. Each of peripheral surfaces 16 and 17 should be at least as great in length as the radius of circle 15 in order to provide adequate cooling and vision of the workpiece during operation of the device.

It is evident that with the foregoing described construction, the working surfaces 13 and 14 will successively contact the workpiece, such periods of contact between the different working surfaces and the workpiece being separated by periods during which the grinding Wheel is not in contact with the workpiece. In this manner, both the workpiece and the grinding wheel are allowed to cool between successive periods of contact between surfaces 13 and 14 and the workpiece. Cooling of the workpiece is augmented by the fact that the flat peripheral surfaces 16 and 17 produce a fan effect, which creates a fiow of cool air over the workpiece. The flattened peripheral surfaces 16 and 17 also permit the point of contact between the workpiece and the grinding wheel to be more readily viewed at all times in contrast to the continuous circular wheels utilized in the prior art wherein it is extremely difficult to observe the progress of the work during grinding operations. In this manner, the operator has much greater control over the depth of cut made in the worl'piece. Since the temperature of the workpiece and the grinding wheel are substantially reduced, the life of the grinding wheel is greatly increased and the period of usefulness of the grind-' ing wheel may be as great as three times that obtained with prior art grinding wheels. In addition, the construction of the invention device is such that the body member tends to be self-cleaning, thereby preventing the glazing or build-up of material being ground on the working surfacesiof the Wheel.

It is evident from the foregoing that there is provided a new and novel grinding apparatus wherein the temperature of the workpiece and the grinding wheel are reduced to a minimum and the point of contact between the grinding wheel and the workpiece is more readily visible at all times. The invention device substantially eliminates the necessity of cleaning off ground material from the working surfaces thereof and the device is simple 20 and inexpensive in construction, yet sturdy and reliable in operation.

' Obviously many modifications and variations of the present invention are possible in thelight of the above teachings. it is therefore to be understood that Within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. Self air-cooled grinding apparatus comprising a flattened body member adapted to rotate about the central axis thereof, said body member having a pair of diametrically opposite substantially arcuate working surfaces, the corresponding end portions of said working surfaces being connected by a pair of diametrically opposite substantially fiat peripheral fan surfaces disposed radially inward of said working surfaces said fan surfaces creating an air fiow directed to the working surfaces.

2. An apparatus as defined in claim 1 wherein said working surfaces comprise approximately one-half the peripheral surface of said body member.

3. Apparatus as defined in claim 1 wherein the length of each of said flat surfaces is at least as great as the radius of curvature of said Working surfaces.

References Cited in the file of this patent UNITED STATES PATENTS t Geofirion Feb, 18, 1941 Great Britain July 24, 1940

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