US3653857A

US3653857A - Abrading implement

Info

Publication number: US3653857A
Application number: US21358A
Authority: US
Inventors: Albert Field
Original assignee: Field Abrasive Manufacturing Co Inc
Current assignee: Field Abrasive Manufacturing Co Inc
Priority date: 1970-03-20
Filing date: 1970-03-20
Publication date: 1972-04-04
Anticipated expiration: 1989-04-04

Abstract

A unique abrasive disk unit includes a piece of vulcanizable rubber sandwiched between a single abrasive coated ply and a backing disk of fiber material. A stud or fitting is installed centrally within the backing disc and is adapted to be removably secured to a mandrel. The components are assembled in a mold, and the rubber is vulcanized by the application of heat and pressure to form an integral unit having strong flexural properties and a high resistance to deterioration from frictional heat.

Description

United States Patent Field 51 Apr. 4, 1972 [54] ABRADING IMPLEMENT [72] Inventor: Albert Field, c/o Field Abrasive Manf. Co., lnc., 1303 Stanley Avenue, Dayton, Ohio 45404 [22] Filed: Mar. 20, 1970 [21] Appl.No.: 21,358

[52] US. Cl ..51/358, 51/297, 51/299 [51] Int. Cl ..B24d 13/14 [58] Field oiSearch ..5l/358,376378, 51/407, 297, 299

[56] References Cited UNITED STATES PATENTS Matouka ..51/358 X 2,950,584 8/1960 Welch ..51/378 3,082,582 3/1963 .leske ..5l/407X Primary Examiner-Donald G. Kelly Attorney-Marechal, Biebel, French & Bugg [57] ABSTRACT A unique abrasive disk unit includes a piece of vulcanizable rubber sandwiched between a single abrasive coated ply and a backing disk of fiber material. A stud or fitting is installed centrally within the backing disc and is adapted to be removably secured to a mandrel. The components are assembled in a mold, and the rubber is vulcanized by the application of heat and pressure to form an integral unit having strong flexural properties and a high resistance to deterioration from frictional heat.

7 Claims, 4 Drawing Figures Patented April 4, 1%72 IN VE/V 706 FIG FIG-l q;

ALBERT FIELD WWMiW A TTOR/VE Y5 ABRADING IMPLEMENT BACKGROUND OF THE INVENTION In abrading implements of the type which employ a single abrasive-coated cloth or paper ply, the ply is usually bonded to a flexible metal or plastic backing with a relatively thin coating of adhesive material or the like. Commonly, the backing is provided with a metal fitting for connecting the disk to the working head of the mandrel. Such abrading implements are used for de-burring dies, metal patterns, welding spots and the like, and are usually flexible so that they may be applied to a curved working surface.

One problem with such an arrangement is that the frictional drag imparted through the workpiece creates a high heat of friction which, after a period of time, softens the adhesive material and weakens the bond between the ply and the backing. Often the bonds are deteriorated to the point that the ply will begin to slip relative to the backing and eventually be completely separated from it.

Another problem is that adhesive materials form relatively rigid bonds which have very little elasticity. When the abrasive ply is compressed against a curved workpiece, the bending creates a stretching force at the point of flexure, and the adhesives do not have the elasticity and heat resistance to withstand the high frictional heat. As a result, the ply often separates from the backing before it has been put to complete use.

The methods for assembling adhesively bonded disk units usually include the steps of applying the adhesive material to the interface between the abrasive ply and backing, clamping the ply and backing together, and allowing the adhesive to dry. While such processes are relatively simple and straightforward, they do not produce units which have high flexural strength and high resistance to frictional heat.

SUMMARY OF THE INVENTION The present invention is directed to an improved abrading implement and includes a new form of abrasive disk unit and a 1 new method of assemblying the same. In general, a relatively thick pad of rubbery material is disposed between the abrasive ply and the backing and positively bonds them into an integral unit upon the application of heat and pressure.

In accordance with a preferred embodiment of the invention, a piece of vulcanizable rubber is sandwiched between the abrasive ply and the backing disk and is vulcanized by applying heat. A metal stud or fitting is installed centrally within the backing disk and is riveted over onto the backing surface. The resulting rivet portion is incorporated into the unit while the rubber is being vulcanized. A threaded end on the fitting extends from the backing disk and is received in an internally threaded bore in the working head of the mandrel.

The improved process includes the steps of installing the components in a mold, heating the mold to about 400 F., and applying pressure to the components to spread the rubber over the adjacent surfaces of the abrasive ply and the backing disk. The rubber is allowed to fill the minute voids in the fiber backing and in the cloth ply for a period of time, and is then pennitted to cool. The process produces an integral abrasive disk unit which has strong and flexible bonds which are highly resistant to deterioration from frictional heat.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view, partly in section, showing the preferred embodiment of the invention;

FIG. 2 is an exploded perspective view, partly in fragmentary section, showing the parts embodied in the preferred embodiment of the present invention;

FIG. 3 is a view of the parts of the abrasive disk unit assembled in a representative mold, and showing a forming die disposed above the parts; and

FIG. 4 is a view of the parts of the abrasive disk unit afte they have been formed into an integral unit by heating the mold and applying pressure through the die.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the abrading implement 10 of the present invention includes a mandrel l1 and an abrasive disk unit 12. The mandrel 11 is provided with a rotatable arbor or shank 13 which is adapted to be attached to the chuck of a hand drill or some other source of power for rotating the implement. One end of the shank 13 is provided with an integral working head 14, and the end face 15 thereof has a conical recess 16 terminating in an internally threaded bore 18. The

end face 15 is preferably fiat for engagement with the bottom of the abrasive disk unit 12.

The unit 12 includes a single ply 20 of adhesive coated fabric or paper having an uninterrupted surface, a backing disk 22 having a center hole 23 and preferably formed of a fibrous material, such as fiberboard, and a metal stud 25 with external threads on one end for threading into the mandrel bore 18. The stud 25 is inserted through the center hole 23 until the backing 22 is flush with the central flange 26, and its smaller end is riveted over at 28 upon the adjacent surface to clamp the disk 22 tightly against the flange 26.

In accordance with the present invention, a piece of vulcanizable rubber 30 is sandwiched between the adhesive ply 20 and the fiber backing disk 22. Preferably, the piece of rubber 30 is made from crude rubber which has been kneaded and thoroughly mixed with vulcanizing ingredients and formed into a sheet which may be cut into squares or the like. Some vulcanizing ingredients which are commonly used are: sulfur or sulfur-bearing materials, or combinations of these with selenium or tellurium, guinoid structures, and dinitrobenene. vulcanizable synthetic rubber, which may utilize other vulcanizing ingredients, can be used as well.

The method of assembling the abrasive disk unit 12 includes the step of assembling the parts in a suitable mold 32. Referring to FIGS. 3 and 4, this may be done by placing the adhesive ply 20 into the bottom of the mold so that the cloth backing is exposed, placing the piece of vulcanizable rubber 30 on the cloth backing, and then placing the fiber backing 22 and installed metal fitting 25 on top of the rubber. As shown in FIG. 3, the rivet portion 28 protruding through the fiber backing 22 will rest on the rubber 30 and space the backing above the rubber.

The mold is then heated to a temperature which is sufficient to vulcanize the rubber. The vulcanizing temperature will of course depend upon the mass of the rubber, the type of rubber used, and the method of heating. Usually, crude rubber can be vulcanized by heating at 200 to 400 F. for varying periods of time. Since the abrasive disk unit 12 is formed simultaneously with the vulcanizing process, the vulcanization may be carried out by using heat alone, or by using heat combined with pressure.

In accordance with the preferred embodiment of the invention, pressure is used to form the product simultaneously with the vulcanization process. Once the rubber 30 has been heated to its vulcanizing temperature, a forming die 34 is brought down to engage the exposed surface of the fiber backing 22 (FIG. 4). Sufficient pressure is exerted to embed the rivet portion 28 in the softened rubber and to spread the rubber over the cloth backing of the adhesive ply 20 and the fiber backing 22. The pressure is held for a period of time to permit the rubber to fill into the minute voids in the cloth backing and the fiber backing. It has been found that a pressure of p.s.i. applied for a period of approximately 8 minutes at 400 F. will satisfactorily vulcanize a 2 inch by 2 inch and one-fourth inch thick square of rubber into an integral disk unit having an overall diameter of 3 inches and with a disk 22 about 2 inches in diameter. For purposes of economy and appearance, the mold 34 is preferably constructed with a frusto-conical configuration so that the rubber will flow and form a smooth circumferential surface 36 extending from the radial extremity of the fiber backing 22 to the radial extremity of the abrasive ply 20.

From the drawing and the above description, it is apparent that certain advantages and features are provided by the present invention. For example, during the vulcanization process the rubber will penetrate into minute voids in the fiber backing 22 and in the cloth ply 20 and, when cured will fonn a multiplicity of strong and flexible bonds between the rubber and the adjacent surfaces of the backing 22 and the ply 20. Moreover, the rivet portion 28 is embedded and bonded into the relatively thick rubber layer. The vulcanization process creates bonds which will not deteriorate under the high temperature generated by frictional drag.

Furthermore, when the rubber is vulcanized it maintains its elasticity while its plasticity is reduced. The rubber 30 will therefore permit the peripheral portion of the unit 12 to bend against a curved working surface and at the same time retain its substantially increased bonding characteristics. The elastic bonds will therefore bend with the unit and remain substantially unaffected by high frictional temperatures. At the same time, the relatively stiff fiber disk 22 adequately stiffens the unit as a whole.

Additionally, the vulcanization process of the present invention incorporates all parts in an integral product without requiring the use of adhesive. The process is relatively simple to perform, requiring simple molds, and produces a substantially improved product which has strong flexural properties and a high resistance to deterioration from frictional heat.

While the process and product herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to this precise process and product, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. An abrading implement comprising:

a. an abrasive disk including a backing member having a plurality of minute voids defined therein,

b. a backing disk of fibrous material having a plurality of minute voids defined therein,

c. a stud attached to said backing disk and having portions projecting through said backing disk,

d. a molded, vulcanized material interposed between said backing member of said abrasive disk and said backing disk,

e. portions of said vulcanized material filling said voids in both said backing member and said backing disk and forming an integral flexible unit of said backing member, said stud and said vulcanized material.

2. An abrading implement as defined in claim 1 wherein said stud includes an integral flange for receiving one side of the backing disk flush thereagainst and integral rivet tabs turned over upon the other side of said disk and embedded in said vulcanized material.

3. An abrading implement as defined in claim I wherein said backing member of said abrasive disk and said backing disk each comprise a fibrous material.

4. An abrading implement as defined in claim 1 wherein said backing disk is of substantially smaller diameter than said ply, and said rubbery material includes a frusto-conical portion underlying the portion of said ply lying outwardly of said disk.

5. A process of making an abrading element comprising:

a. securing a stud to a fibrous backing disk having a plurality of minute voids defined therein,

b. placing an abrasive disk including a backing member hav- 1 ing a plurality of minute voids defined therein in a mold,

c. positioning a layer of vulcanizable material in said mold in contact with said backing member,

d. positioning said fibrous backing disk on said layer of vulcanizable material,

e. subjecting the assembly of said backing disk, said backing member and said vulcanizable material to sufficient heat to cause said vulcanizable material to flow into said voids in said backing disk and said backing member and vu lcanize said backing member, said backing dlSk and said

Claims

1. An abrading implement comprising: a. an abrasive disk including a backing member having a plurality of minute voids defined therein, b. a backing disk of fibrous material having a plurality of minute voids defined therein, c. a stud attached to said backing disk and having portions projecting through said backing disk, d. a molded, vulcanized material interposed between said backing member of said abrasive disk and said backing disk, e. portions of said vulcanized material filling said voids in both said backing member and said backing disk and forming an integral flexible unit of said backing member, said stud and said vulcanized material.

3. An abrading implement as defined in claim 1 wherein said backing member of said abrasiVe disk and said backing disk each comprise a fibrous material.

5. A process of making an abrading element comprising: a. securing a stud to a fibrous backing disk having a plurality of minute voids defined therein, b. placing an abrasive disk including a backing member having a plurality of minute voids defined therein in a mold, c. positioning a layer of vulcanizable material in said mold in contact with said backing member, d. positioning said fibrous backing disk on said layer of vulcanizable material, e. subjecting the assembly of said backing disk, said backing member and said vulcanizable material to sufficient heat to cause said vulcanizable material to flow into said voids in said backing disk and said backing member and vulcanize said backing member, said backing disk and said material into an integral unit.

6. The process of claim 5 further comprising: a. applying pressure to said assembly during heating thereof.

7. A process as defined in claim 6 wherein said stud includes a rivet portion turned over on the surface of said backing disk adjacent said rubber, and sufficient pressure is applied to embed said disk and rivet portion in said rubber.