US3186135A - Abrasive disc - Google Patents

Description

J. E. CREAN ABRASIVE DI SC June I, 1965 Filed April 4, 1962 FIG.

FIG.

INVENTOR. JOHN E. CREAN ATTORNEY United States Patent 3,186,135 ABRASIVE DISC John E. Crean, Willowdale, Ontario, Canada, assignor to The Carborundurn Company, Niagara Falls, N.Y., a corporation of Delaware Filed Apr. 4, 1962, Ser. No. 184,977

2 Claims. (Cl. 51--394) This invention relates generally to an abrasive disc and more particularly to an abrasive disc of noncircular configuration which has rounded projections extending radially therefrom. V

Abrasive discs are used for grinding, polishing and finishing metallic surfaces. The discs are rotated in a circular fashion and the abrasive surface of the disc is held against the metallic surface. It has been found that abrasive discs of noncircular configuration are in many respects superior to abrasive discs having a circular con figuration.- This'is especially true where the metallic surfaces are curved. The disc having a noncircular configuration with the projections extending radially therefrom is self-cleaning in that the material, either dislodged abrasive or metal particles dislodged by the main central portion of the disc, is discharged from beneath the disc between the radial projections. When compared with a disc having a circular configuration, the dislodged material cannot be discharged from beneath the disc until it is conveyed beyond the circumferential edge of the disc. It is also believed that the accumulation of dislodged abrasive and metallic particles along the peripheral edge of the disc causes irregular finishing of the metallic surface. The abrasive disc with a noncircular configuration and radial projections minimizes the accumulation of the dislodged material along the peripheral edge of the disc and provides a more uniform finish to the metallic surface.

In the past, the abrasive discs having a noncircular configuration all had peaked projections extending radially therefrom. The peaked projections had sharp corners so that the peripheral edge of the abrasive disc comprised a series of straight line linear edges joined to each other at the angular peaked portion. Some of the discs were rectangular in configuration and others were; octagonal in configuration. An octagonal disc with the sharp peaked projections is illustrated in Patent No. 2,746,216, granted on May 22, 1956, and entitled Sanding Attachment.

Although the disc having a noncircular configuration and sharp peaked projections is superior to an abrasive disc of circular configuration for certain applications, it has been discovered that the use of the abrasive disc with the sharp corners is limited when the disc is used on metallic surfaces having rough jagged edges and when used on metallic surfaces with sharp angular portions.

The sharp corners of the disc have a tendency to snag on the jagged edges of the metal and break or tear the disc. The sharp corners of the disc have a tendency to break down after a short period of use when the abrasive disc with sharp corners is used on medium rough edged material. This reduces the useful life of the abrasive discs and results in unnecessary expense in the grinding or polishing operation. When an abrasive disc having sharp corners is used on an angular surface, that is, a surface having a substantially horizontal portion and an upstanding portion, the sharp corners tend to snag on the upstanding portion and break or tear the disc. This presents a difficult problem in grinding or polishing the surface at the angular juncture of the horizontal portion and the upstanding portion.

I have discovered by rounding off the sharp corners of the abrasive disc that I am able to retain the advantageous features of an abrasive disc having a noncircular con- I figuration; and yet eliminate the problems heretofore discussed. I have found by rounding olf the sharp corners and providing a smooth curved projecting portion that I am able to increase the useful life of the abrasive disc. The abrasive disc with smooth curved projecting tion with curved projections extending radially therefrom.

Another object of this invention is to provide an abrasive disc of noncircular configuration and rounded corners that has increased life and is suitable for use on material having jagged edges.

Another object of this invention is to provide an abrasive disc having a generally octagonal configuration with rounded corners.

With the above and other objects in view, which will appear as the description proceeds, the features of the invention reside in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiments of the invention may be made without departing from the spirit of the invention.

FIGURE 1 is a view in plan of one embodiment of my abrasive disc.

' FIGURE 2 is a View in section taken along the lines 11-11 of FIGURE 1.

Referring particularly to FIGURES 1 and 2, there is illustrated one embodiment of my abrasive disc generally designated by the numeral 10. The abrasive disc 10 is illustrated as having a cellulosic backing 12 having a surface 14 onto which is bonded a layer of grit 16. The grit 16 may be any suitable abrasive such as carbide or aluminum oxide grains of any desired grit size. The backing 12 may also be a vulcanized fibrous material laminated to a layer of cloth with a phenol formaldehyde resin or the like. The layer of abrasive 16 is bonded to the backing 12 by means of a suitable bonding material, for example a phenol formaldehyde resin. It should be understood that any suitable backing and abrasive may be employed Without departing from the scope of this invention.

The abrasive disc 10 has a central shaft receiving aperture 18 therethrough and a central circular portion 39. The circumferential boundary of the central portion 30 is illustrated by the dotted line 32. It should be understood that in the embodiment illustrated in FIGURE 1 the designation of the central portion 30 with its circumferential boundary designated by slotted line 32 is not intended to indicate that the central portion is formed separately of the noncircular projections. The designation of the circular portion 30 is for convenience only to more clearly point out the improved shape of the peripheral edge portion of the disc illustrated in FIGURE 1. Extending radially outwardly from the disc central circular portion 30 are a plurality of rounded projections or curved lobe portions 34. The adjacent lobe portions 34 are joined by a curved portion 36 so that the peripheral edge portion of disc 10 may be considered as having a rosette shape. The portions 34 may be considered as being curved portions extending radially outwardly of the central circular portion 30 and the curved edge portions 36 may be considered as curved portions extending radially inwardly toward the central circular portion 30.

The peripheral edge portion of disc is sinusoidal in shape in that a regular curve similar to a sine wave would be formed if the peripheral edge of the disc 10 were projected on a flat surface. I

It has been found by employing disc 10 on rough edged material that the discs are less likely to snag or break than discs having sharp corners. In finishing material that has sharp angles, it has been found that the peripheral edge of the disc herein described does not snag on the upwardly extending portion of the material as the material adjacent the angular portion is finished. With discs having sharp corners the sharp corner portions have a tendency to snag on the upwardy extending portion of the metal and break or tear. It is also now possible with the abrasive discs herein described to provide a smoother finish adjacent angular projections on the material being finished.

According to the provisions of the patent statutes, I have explained the principle, preferred construction, and mode of operation of my invention and have illustrated and described what I now consider to represent its best embodiments. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. An abrasive disc which comprises a continuous, nonsegmented base member and abrasive grain bonded to one surface of said base member, said disc having a central circular portion and a curved peripheral edge portion,

said curved peripheral edge portion being formed of a plurality of radially inwardly curved edge portions and a plurality of radially outwardly curved edge portions, said radially inwardly curved edge portions forming a smooth junction between said radially outwardly curved edge portions so that said peripheral edge portion is substantially free of sharp pointed corners.

2. A disc of abrasive material having a continuous, nonsegmented base member and abrasive grain bonded to one surface of said base member, said disc being suitable for use on material having jagged edges, said disc having a circular central portion and a curved peripheral edge portion, said curved peripheral edge portion including a plurality of radially inwardly curved edge portions and a plurality of radially outwardly curved edge portions, said curved peripheral edge portion formed of alternating inwardly curved edge portions and outwardly curved edge portions, said radially inwardly curved edge portions blending with said adjacent outwardly curved edge portions to form a smooth junction therebetween.

References Cited by the Examiner UNITED STATES PATENTS 1,216,488 2/17 Pfeilfer 51-195 2,307,632 1/ 43 Meyer 51-209 2,492,143 12/49 Gipple et al. 51196 2,746,216 5/56 Hollingsworth 51195 FOREIGN PATENTS 804,762 4/51 Germany.

LESTER M. SWINGLE, Primary Examiner.

FRANK H. BRONAUGH, J. SPENCER OVER- HOLSER, Examiners.

Claims (1)

1. AN ABRASIVE DISC WHICH COMPRISES A CONTINUOUS, NONSEGMENTED BASE MEMBER AND ABRASIVE GRAIN BONDED TO ONE SURFACE OF SAID BASE MEMBER, SAID DISC HAVING A CENTRAL CIRCULAR PORTION AND A CURVED PERIPHERAL EDGE PORTION, SAID CURVED PERIPHERAL EDGE PORTION BEING FORMED OF A PLURALITY OF RADIALLY INWARDLY CURVED EDGE PORTIONS AND A PLURALITY OF RADIALLY OUTWARDLY CURVED EDGE PORTIONS, SAID

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