US2540112A

US2540112A - Abrasive wheel

Info

Publication number: US2540112A
Application number: US135691A
Authority: US
Inventors: George J Goepfert; Louis L Cofran
Original assignee: Carborundum Co
Current assignee: Unifrax 1 LLC
Priority date: 1949-12-29
Filing date: 1949-12-29
Publication date: 1951-02-06
Anticipated expiration: 1968-02-06
Also published as: GB673334A

Description

Feb 6, 1951 G. J. GOEPFERT rs1-Al. 2,540,112

ABRASIVE WHEEL Filed Dec. 29, 1949 INVENTOR. GEORGE J GOEPFERT BY OU/5 L. COI-'PAN Patented Feb. 6, 1951 STATES, PATENT ortica ABRASIVE WHEEL George J. Goepfert and Louis L. Cofran, Niagara Falls, N. Y., assignors to The Carborundnm Company, Niagara Falls. N. Y., a corporation of Delaware Application December 29, 1949, Serial No. 135,691

10 Claims. (Cl. 51206) are often used for dressing operations in the finishing of metal articles, grinding out fillets and the like, although due to their thinness they can also be used for cutting-off purposes.

The present invention is especially adapted to A abrasive wheel.

body of the wheel at the time that it is formed two or more sheets or plies of suitable nonabrasive fabric. Most satisfactory results have been obtained by using a resin-impregnated woven fabric which is preferably placed in from, but adjacent to, each flat side surface of the In other words, although the impact strength of an abrasive Wheel, such as a thin cut-oil wheel, composed of abrasive-included fibrous material is increased by placing the woven fabric plies within the wheel either adjacent the sides of the wheel or in more nearly the center portion laterally of the wheel, the flexural abrasive cutting-off wheels and wheels of similar structure and will therefore be primarily described as it pertains to such wheels although it is pointed out that it is also applicable to other types of grinding wheels wherein the grinding is performed at or on the periphery of the wheel.

Conventional cut-off wheels of the prior art are usually composed of abrasive grains held together by a suitable resinous or rubber bond. They are used at high speeds ofirevolution but in order to'provide the requisite hardness to produce a fast and cool cutting rate without excessive wheel wear the bond is necessarily cured or vulcanized to an extremely hard condition. As a result the abrasive Wheels so made are of very low exural strength so that wheel breakage frequently occurs when th-` wheel is subjected to the least lateral stress or impact with not only loss of the wheel before it has served its useful life but with considerable danger to the operator. This deficiency in impact and/or flexural strengths has never been satisfactorily overcome.

It is an object of the present invention to provide an abrasive wheel having a satisfactory performance life and an acceptable high cutting rate.

It is a further object to provide an abrasive wheel which notonly has a satisfactory life and cutting rate but also is of high impact and flexural strengths.

Other objects and advantages accruing from the practice of the present invention will become apparent as the description proceeds.

We have found that abrasive wheels with satisfactory life and cutting rate, having high impact and flexural strengths, can be made by forming the wheels of a felted fibrous abrasivecontaining material and embedding within the strength of such a wheel is not greatly improved unless the woven fabric layers are positioned in from, but in the vicinity of, the two wheel sides. The fabric to be selected for promoting the impact and flexural strengths by embodiment within the wheel should be of such character that the edges of the fabric at the periphery of the wheel will break down during the operation of the wheel without smearing or otherwise interfering with the grinding or cutting function. At the same time the fabric must have a durability and strength of its own suihcient to impart to the wheel the desired increase in both impact and flexural strengths. Such a combination of functions is most readily obtained by using a fabric which has been impregnated with a heathardenable resin. We have found a woven fabric such as a canvas, duck, or drill cloth impregnated with a phenolic condensation product resin to be highly satisfactory for the purpose.

A uniform thickness of the thin side layers of abrasive-included fibrous material forming the two dat side surfaces of the wheel, as well as a uniform thickness and density of the main body portion of abrasive-included brous material is best obtained by using an abrasive-included fibrous material in the form of thin sheets or plies cut to the shape of thin circular discs. The number of plies used for each side surface section, as well as for the central body portion, of the wheel will depend largely upon the thickness of wheel desired.

One abrasive-containing brous material which has been found highly suitable for making abrasive wheels in accordance with the present invention is the abrasive-included felted fibrous sheet material disclosed and fully described in U. S. Patents Nos. 2,284,738 and 2,284,739. In making an abrasive wheel such as an abrasive cutting-off wheel using the sheet material of the above patent the sheet material is died, punched or otherwise cut out in the form of a number of circular discs of a diameter slightly greater than vthe diameter of the wheel to be made. The sheet material either before or after it is cut to this form is sized with a suitable combining adhesive which is allowed to dry to a substantially nontacky condition in which it is suitable for handling. One or more discs of the abrasive-containing felted fibrous sheet material are placed on the bottom mold plunger in a molding press, and superposed by a disc-shaped sheet of the chosen fabric. The abrasive-containing sheet material which is to make up most of the abrasive wheel body structure is then placed upon the fabric sheet, after which a second fabric sheet similar to the irst sheet of fabric is superimposed on the pile of material, followed finally by one or more additional layers of the abrasive-containing felted fibrous sheet material. The entire assembly after alignment is then subjected to heat and pressure sufficient to compact and unite the various plies of material. the compacted wheel shape removed from the mold, and dressed if necessary, after which it is ready for use. If desired, the wheel can be formed by either a hot or cold pressing operation, followed by curing at a temperature and time suillcient to finally cure or mature the combining adhesive of the wheel structure.

In order to better understand the nature of the abrasive articles with which we are here concerned, reference is made to the accompanying drawing showing specific examples of abrasive wheels made in accordance with the present invention, and in which:

Figure 1 is a top plan view of an abrasive cutof! wheel made in accordance with the present invention;

Figure 2 is a highly enlarged sectional view through the line 2--2 of Figure 1; and

Figure 3 is a view, similar to that shown in Figure 2, of a modified form of abrasive wheel made in accordance with the present invention.

The exact manner in which abrasive wheels can be easily and economically made following the teachings of the present invention is most easily demonstrated by the following examples setting forth specific procedures for the making of illustrative abrasive products.

Eample I Abrasive cut-oil wheels 16" in diameter and in thickness having a 1" arbor hole have been made as follows: An abrasive-containing felted fibrous sheet material of the type described in U. S. Patents Nos. 2,284,738 and 2,284,739 and composed of a felted cotton fiber base sheet held together by a casein adhesive and containing approximately 85-90% by weight of 24 grit size aluminum oxide abrasive grain is ilrst sized on one side with a thin sizing coat o f liquid phenolic resin prepared from the reaction product of 1 mole of phenol and from 1.1 to 2 moles of formaldehyde, said reaction being catalyzed by the addition of an alkaline catalyst, and the resin dried to a non-tacky condition. A number of circular discs 16%" in diameter having centrally located arbor holes 1l in diameter are punched out of the sized abrasive-containing brous sheet material. One disc of the abrasive-included fibrous sheet material is placed on a 16%" diameter steel wheel mold plunger of the conventional type after which a disc-shaped sheet of resinimpregnated woven fabric of the same diameter is placed on the mold plunger on top of the single dien nf nhrn giundnn'lnn hmnn chant mnhn'lnl One material which has been satisfactorily used for this purpose is a bluecotton drill impregnated with a phenolic condensation product resin such as that obtained from the reaction of 1 mole of phenol with 1.5 moles of formaldehyde in the presence of a small amount of an organic primary amine catalyst. Ten layers of abrasive-included felted ilbrous sheet material the same as that first placed on the mold plunger are then placed on top of the resin-impregnated fabric, followed by a single additional layer of resin-impregnated fabric which is topped in turn by a final single layer of the abrasive-included fibrous sheet material. The top mold plunger is then placed upon the assembled sheet material and the entire assembly axially aligned and pressed at 4000 pounds per square inch pressure at a temperature of 300 F. for 15 minutes. The thusly molded wheel is then removed from the press, dressed to size in accordance with conventional procedures, after which it is ready for use.

Referring further to Figures 1 and 2 of the drawing, which illustrate an abrasive cut-oil.' wheel such as that made in accordance with Example I above, the abrasive wheel 4 having an arbor hole 5 is composed of abrasive-included felted fibrous sheet material 6 and two sheets 1 of resin-impregnated woven fabric, the woven fabric layers 1 being located within the wheel adjacent the nat side faces 8 and 9 of the wheel although they do not constitute the flat surfaces of the wheel since they are faced in each instance by surface layers 6a and 6b of the abrasiveincluded gelted fibrous sheet material. It is noted that the thickness of the wheel as depicted in Figure 2 of the drawing has been greatly exaggerated in order to bring out more clearly the structural make-up of the wheel.

A cut-off wheel of the described type has been demonstrated to have a highly satisfactory performance life and a high cutting rate. At the same time a cut-oil wheel of the described type having two layers of resin-impregnated woven fabric adjacent the side faces of the wheel as shown in Figure 2 has been found to have a flexural strength as much as 35-40% greater than the strength of similar laminated abrasive cut-of! wheels in which the resin-impregnated fabric layers have been omitted. As an example of the extremely high flexural strengths obtainable in wheels made in accordance with the present invention abrasive cut-oil.' wheels of the type hereinabove described have been subjected to a grinding test in which the wheels have been used to cut directly into a piece of solid brass rod 2" in diameter to a depth of more than 1" whereupon the brass rod without removal of the wheel is turned laterally through an angle as high as 45 in each direction. Abrasive wheels of the present invention when subjected to such punishment, cut wedge-shaped sections out of the bram rod without breakage of the abrasive wheel. Conventional resin bonded or rubber bonded cutoi! wheels of the same diameter and thickness, and also abrasive cut-off wheels of similar size composed of abrasive-included fibrous sheet material in which the plies of resin-impregnated fabric have been omitted, when subjected to the same test failed to stand up, usually shattering with explosive violence. The ability of the wheels of the present invention to resist breakage or damage under the severe conditions of such a test under which other wheels generally fail is adramatic demonstration of their marked 'I material compressed and adhesively united, said wheel having embedded therein at least two layers of resin-impregnated woven fabric substantially coextensive in area with the flat side area of said wheel.

2. An abrasive cut-oif wheel composed of a body of abrasive-containing felted fibrous material and having a layer of woven fabric substantially coextensive in area with the flat side of the wheel embedded within but adjacent to each flat side surface thereof.

3. An abrasive cut-oi! wheel composed of a body of abrasive-containing felted fibrous material and having. a layer of resin-impregnated woven fabric substantially coextensive in area with the fiat side of the wheel embedded within but adjacent to each flat side surface thereof.

4. An abrasive cut-off wheel conforming to claim 3 in which the impregnating resin is a resinous phenolic condensation product.

5. An abrasive wheel comprising in the following order from one flat side to the opposing fiat side: a thin layer of abrasive-containing felted brous material, a layer of resin-impregnated woven fibrous material, a plurality of layers of abrasive-containing felted fibrous material, a layer of resin-impregnated woven fibrous material, and a layer of abrasive-containing felted fibrous material, all said layers being compressed together and adhesively united.

6. An abrasive cut-off wheel composed of a body of abrasive-containing felted fibrous material and having at least one layer of resin-impregnated non-abrasive fabric substantially coextensive in area with the at side of the wheel embedded within but adjacent to eachflat side surface thereof.

7. An abrasive cut-olf wheel comprising a plurality of abrasive-containing felted fibrous sheets composed essentially of abrasive grains. felted fibers and binder. said sheets of abrasive material being compressed and adhesively united. said wheel containing within the body thereof adjacent each flat side at least one layer of resinimpregnated non-abrasive fibrous material substantially coextensive in area with the side area of said wheel.

8. An abrasive wheel comprising in the following order from one flat side to the opposing flat side: at least 1 sheet of abrasive-containing felted nbrous material, at least 1 sheet of resinimpregnated woven fibrous material, a plurality of layers of abrasive-containing felted fibrous material. at least l sheetof resin-impregnated woven fibrous material, and at least 1 sheet of abrasive-containing felted fibrous material, all said layers being compressed together and adhesively united.

9. An abrasive cut-off wheel composed of a body of abrasive-containing felted fibrous material and having a layer of resin-impregnated non-abrasive fabric substantially coextensive in area with the flat side of the wheel embedded within but adjacent to each flat side surface thereof.

10. An abrasive wheel comprising a plurality of thin felted, abrasive-containing layers of fibrous material compressed and adhesively united, said wheel having embedded therein at least one sheet of resin-impregnated woven fabric adjacent each fiat side of the wheel.

GEORGE J. GOEPFERT. LOUIS L. COFRAN.

No references cited.

Claims

1. AN ABRASIVE WHEEL COMPRISING A PLURALITY OF THIN FELTED, ABRASIVE-CONTAINING LAYERS OF FIBROUS MATERIAL COMPRESSED AND ADHESIVELY UNITED, SAID WHEEL HAVING EMBEDDED THEREIN AT LEAST TWO LAYERS OF RESIN-IMPREGNATED WOVEN FABRIC SUBSTANTIALLY COEXTENSIVE IN AREA WITH THE FLAT SIDE AREA OF SAID WHEEL.