US 3333372 A
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United States Patent 3,333,372 ABRASIVE BELT Henry L. Gianatasio, Oak Park, Ill., assignor to Pres-0n Abrasives, Inc., Addison, Ill., a corporation of Illinois Filed Dec. 3, 1964, Ser. No. 415,699 1 Claim. (Cl. 51--399) ABSTRACT OF THE DISCLOSURE More particularly, the invention relates to an endless abrasive two-ply belt, the outer surface of the outer ply or base sheet has abrasive particles adhesively secured thereto. This base sheet has a joint with abutting end portions cut at an angle of about 45 degrees relative to the side edge, the inner ply is adhesively bonded to the inner surface of the outer ply and comprises a flexible reinforcing film composed of material selected from the group of film-forming material consisting of polyethylene terephthalate and vulcanized fiber. This film has a fused joint spaced from the joint of the first ply and also traversing the belt at an acute angle to the edge thereof.
This invention relates to an abrasive belt and, more particularly, to an abrasive belt which is adapted for use with belt sanders, and like tools.
Endless abrasive belts for use with belt sanders and like tools have been known heretofore but these have been subject to a number of problems and difficulties in use. Thus, one problem which has been involved in the use of such endless abrasive belts has been the fact that the joint uniting the end portions of the abrasive coated flexible base material has commonly created a raised area over the surface of the joint with the result that such joints tend to wear out at the end portions of the abrasive coated flexible material and pull away from each other under the stresses and strains to which such endless abrasive belts are subjected in use.
Accordingly, an object of the present invention is to provide a new and improved endless abrasive belt, for use in belt sanders, and the like, which is free from the objectionable features of the prior art devices including the difficulties experienced in the areas where the end portions of the belt are joined together and other problems and difliculties involved in the use thereof.
Another object of the present invention is to provide a new and improved endless abrasive belt in which the thickness of the belt at the seam or joint between the end portions thereof does not differ substantially from the thickness of the belt throughout the body thereof.
Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings, which, by way of illustration, show a preferred embodiment of the present invention and the principles thereof and what I now consider to be the best mode in which I have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention.
In the drawings:
FIG. 1 is a perspective view of an endless abrasive belt embodying the present invention;
FIG. 2 is a fragmentary enlarged sectional view on line 22 in FIG. 1;
FIG. 3 is an enlarged fragmentary sectional view on line 33 in FIG. 1; and
FIG. 4 is a top exploded plan view of the component elements of the new endless abrasive belt as they appear prior to the time they are laminated together.
3,333,372 Patented Aug. 1, 1967 A preferred embodiment of the present invention is illustrated in the drawing wherein it is generally indicated at 10, and comprises a base sheet of flexible material such as paper, cloth fabric of suitable quality, or the like, sized and cut to suitable dimensions depending upon the size, etc., of the belt sander, or the tool, with which it is to be used, and other factors.
A layer 13 of finely divided abrasive particles or granules is adhesively secured to the outer surface of the flexible base sheet 12, and a layer 14 of flexible strengthening material is provided on the inner surface of the flexible abrasive sheet 12, the layer 14 of flexible strengthening material being adhesively secured to the inner surface of the flexible base sheet 12 by means of a suitable intermediate adhesive film 1 The layer 14 of flexible strengthening material may be made of suitable selected material such, for example, as a thin film of polyester resin or, alternatively, it may be made of vulcanized fabric in which vulcanized material latex rubber, or suitable synthetic resinous copolymer material, may be incorporated to impart adequate strength thereto.
In the practice of the present invention the layer 14 of flexible strengthening material may also be made from various materials including synthetic rubbery copolymers,
such as a butadiene-styrene synthetic rubber material,
which may be reinforced with additional or tougher resins, and the rubbery adhesive material may be incorporated in a suitable solvent system such, for example, as methyl ethyl ketone (MEK) so as to provide a suitable bond with the adhesive layer or film 15.
However, it has been found in the practice of the present invention that the flexible strengthening layer or film 14 is preferably made of a polyethylene terephthalate film or so-called MYLAR (a Du Pont trademark) film because, unlike polyethylene, this material is tough and, being somewhat polar, can be adhered to other materials with relative ease. In addition, it is not brittle, as are certain other film-forming materials, including some acrylic films, styrenes, and like synthetic resinous materials.
Moreover, the polyethylene terephthalate (Mylar) film, being thermoplastic the end portions 18 thereof may be joined or laminated together by heat fusion or heat sealing.
In the manufacture of the new endless abrasive belt 10 it is necessary, however, to select an adhesive 15 which is not only compatible with the layer 14 of flexible strengthening material but which also achieves a good bond with the flexible abrasive base layer or backing sheet 12-13.
In the practice of the present invention the end portions 17 of the abrasive coated base or backing sheet 12 are cut preferably at an acute angle of about 45 (FIG. 4) relative to the parallel side edges there-of, and the end portions 18 of the layer or film 14 of flexible strengthening material are similarly preferably cut at an acute angle relative to the parallel side edges thereof (FIG. 4). The thus angularly cut end portions 17 of the abrasive coated sheet 12-13 are placed in abutting relationship to form the joint or seam 19 (FIG. 1). The non-abrasive surface of the flexible abrasive coated base or backing sheet 12 is then coated with the adhesive coating or film 15, which may be in the form of synthetic latex, or like material, whereupon the end portions 18 of the layer or film 14 of flexible strengthening material, which may be made of Mylar film, or of vulcanized fiber, may be cut at an acute angle relative to the side edges thereof, and the thus cut flexible reinforcing film 14 is then arranged over the adhesive layer or film 15, and secured thereto with the acute angularly cut end portions 18 of the layer or film 14 of flexible strengthening material abutted together, as at 16,
as shown in FIG. 1, and preferably at a joint spaced from the joint 19 provided by the acute angularly cut end portions 17 of the flexible abrasive coated base or backing sheet 12-13 (FIG. 1).
The end portions 18 of the flexible sheet or film 14 may then be heat-fused or heat-sealed together to form the integral joint or bond 16. In this manner an endless abrasive belt is provided which is strong and durable and free from any lumps or raised portions at the butt joint 19 between the end portions 17 of the flexible abrasive coated sheet 12-13, and at the butt joint 16 between the end portions 18 of the flexible strengthening sheet or film 14, and a strong and durable endless abrasive belt 10 is provided which well resists the stresses and strains to which it is subjected in use on a belt sander, or other tool.
It will thus be seen from the foregoing description, considered in conjunction with the accompanying drawing, that the present invention provides a new and improved endless abrasive belt and that the invention thus has thedesirable advantages and characteristics and accomplishes its intended objects including those hereinbefore pointed out and others which are inherent in the invention.
An endless abrasive belt comprising (a) a flexible base sheet including an inner surface and an outer surface,
(b) a layer of finely divided abrasive particles adhesively secured to the outer surface,
() the said abrasively coated flexible base sheet having end portions abutting each other to form a closed, continuous loop,
(d) a film of flexible adhesive material on the said inner surface of the said flexible abrasive coated sheet,
(e) a reinforcing film of tough, flexible reinforcing material bonded to the said adhesive film on the inner surface of the latter,
(f) said flexible reinforcing film being composed of a material selected from the group of film-forming materials consisting of polyethylene terephthalate and vulcanized fiber,
(g) said flexible abrasive coated base sheet having a joint with abutting end portions cut at an angle of about relative to the side edges of the said abrasive-coated flexible base sheet, and
(h) said flexible reinforcing film having a fused joint spaced longitudinally of said belt from said first joint and with abutting end portions cut at acute angles relative to the side edges thereof.
References Cited UNITED STATES PATENTS 2,186,001 1/1940 Bartling 51-407 2,391,731 12/1945 Miller 5l399 2,637,956 5/1953 Nuessle 5l407 2,794,726 6/1957 Riedesel 51-399 X 3,186,135 6/1965 Crean 5l394 FOREIGN PATENTS 417,177 9/1934 Great Britain.
ROBERT C. RIORDON, Primary Examiner.
D. G. KELLY, Assistant Examiner.