US3922820A

US3922820A - Means for feathering rubber stock

Info

Publication number: US3922820A
Application number: US431919A
Authority: US
Inventors: Arthur J Wiltshire
Original assignee: Structural Fibers Inc
Current assignee: Structural Fibers Inc
Priority date: 1974-01-09
Filing date: 1974-01-09
Publication date: 1975-12-02
Anticipated expiration: 1992-12-02
Also published as: CA1009845A

Abstract

Apparatus for skiving edge portions of sheet stock is disclosed. The apparatus includes a table having a surface adapted to support sheet stock so that an edge of the stock is in coplanar relationship with an edge of the table. A pair of rollers are mounted over the table and those rollers drive an endless abrasive belt. The belt has a flat reach extending at an acute angle with respect to the plane of the table and at least a portion of the flat reach overlies and is intersected by a plane normal to the table and passing through the table edge.

Description

United States Patent 1 Wiltshire 1 Dec.2, 1975 I MEANS FOR FEATHERING RUBBER STOCK [75] Inventor: Arthur J. Wiltshire, Richmond FOREIGN PATENTS OR APPLICATIONS 1,835 8/1854 United Kingdom 51/147 Primary Examiner-Al Lawrence Smith Assistant Examiner-Nicholas P. Godici Attorney, Agent, or FirmMcNenny, Farrington, Pearne & Gordon [5 7] ABSTRACT Apparatus for skiving edge portions of sheet stock is disclosed. The apparatus includes a table having a surface adapted to support sheet stockso that an edge of the stock is in coplanar relationship with an edge of the table. A pair of rollers are mounted over the table and those rollers drive an endless abrasive belt. The belt has a flat reach extending at an acute angle with respect to the plane of the table and at least a portion of the flat reach overlies and is intersected by a plane normal to the table and passing through the table edge.

4 Claims, 3 Drawing Figures U.S. Patent Dec. 2, 1975 Sheet 1 of2 3,922,820

U.S. Patent Dec. 2, 1975 Sheet 2 of2 3,922,820

MEANS FOR FEATHERING RUBBER STOCK BACKGROUND OF THE INVENTION This invention relates to skiving apparatus, and more particularly to apparatus for providing a taper along the edges of sheet stock so that the tapered edges may be overlapped and bonded to provide a seam having a thickness corresponding to the thickness of the sheet stock. Devices which are intended to provide skived or feathered edges on sheet stock generally comprise a table having a surface adapted to support the stock and an abrasive belt trained between the rollers. A portion of the belt which is wrapped about one of the rollers is brought into engagement with the edge of the sheet and the roller is then moved along the edge of the sheet from one end thereof to the opposite end. Although this arrangement provides the sheet with a tapered edge, it is not a flat taper which would accurately mate with a corresponding flat taper provided at the opposite edge of the sheet, since the curvature of the roller provides a corresponding curvature to the taper.

While in most applications such a discontinuity may be tolerated, there are situations where precise mating must obtain 'to provide a uniform seam. For example, precise seams are required in forming expandable bags which are employedin forming the interior surface of hollow, fiber-reinforced articles. Such molding tech niques are commonly referred to as bag molding techniques and are set forth in US. Pat. No. Re. 25,241, to D. W. Randolph. According to the techniques described in that patent, hollow, cylindrical, fiber-reinforced plastic tanks have been pressure-molded by laying up fiber matting in a rigid mold casing in the approximate form of the desired article. A complete fiber form may include preformed, matted fiber end wall caps which telescope into a laid up, cylindrical sidewall portion.

An expandable bag or envelope which will define the interior shape of the finished article is positioned within the laid up form in the mold. Rigid casing caps which shape the end walls of the final article are clamped to the ends of the rigid mold casing to enclose the fiber mat form. With the fiber matting and mold thus assembled, the fiber matting is placed under a suitable moderate pressure by expanding the bag to hold it in place against the mold. The fiber matting is then permeated with a thermosetting resin or the like. The bag, besides defining the interior surface of the molded tank and determining the proper fiber-to-resin ratio, compresses the fiber lay-up in such a manner as to avoid migration of fibers with resin flow and resulting destruction of the lay-up. Such bags have been formed by overlapping opposite edge portions of a sheet of neoprene and joining those edge portions by a suitable neoprene cement which sets upon the application of heat. After a hollow neoprene tube has been formed in this manner, a sheet of neoprene is applied to one end of the tube and a sec ond end piece is applied to the other end together with an air fitting.

While such bags have been employed successfully in the manufacture of fiber-reinforced plastic pressure vessels, they have certain defects. One such defect is the fact that the longitudinal, non-feathered lap seam forms a longitudinal ridge in the sidewall of the molded pressure vessel and this ridge provides a structural discontinuity in a zone of abnormal stress concentration when the tank is pressurized.

SUMMARY OF THE INVENTION This invention overcomes these prior art problems by providing apparatus for skiving opposite edges of neoprene sheet stock so that those edges may be accurately mated to produce a seam which does not vary in thickness as compared to the remainder of the stock.

The apparatus comprises a flat table having a surface adapted to support sheet stock and a vacuum gripping means associated with the table to retain an edge of the stock in coplanar relationship with an edge of the table. An endless abrasive belt is mounted between a drive roller and an idler roller to provide a flat reach which extends at an acute angle with respect to the plane of the table. At least a portion of the flat reach overlies and is intersected by a plane normal to the table and passing through the table edge. This arrangement ensures that the sheet stock will be skived to produce a flat tapered edge rather than a curved tapered edge. A carriage and guide rod arrangement guides the rollers and their associated belt in a path along the edge which maintains the portion of the flat reach in its overlying relationship. After making one rough cut pass along the edge of the sheet stock, the direction of the carriage is reversed and the belt and roller assembly is lowered to provide a finish pass.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, perspective view of a skiving arrangement according to this invention;

FIG. 2 is a fragmentary, cross sectional view, the plane of the section being indicated by the line 22 in FIG. 1; and

FIG. 3 is a fragmentary, cross sectional view, the plane of the section being indicated by the line 3-3 in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, there is illustrated a skiving machine 10. The machine 10 includes a flat table 11 adapted to support sheet stock such as the illustrated sheet of neoprene 13. An edge 14 of the sheet 13 is retained in coplanar relationship with an edge 15 of the table 11 by drawing a vacuum through a multiplicity of perforations 16 in the table 11.

The edge 14 is tapered or skived by an endless abrasive belt 17 mounted between a drive roller 18 and an idler roller 19. The belt 17 has a flat reach 20 extending at an acute angle with respect to the plane of the table and, as may be seen in the drawings, at least a portion of that flat reach overlies and is intersected by a plane normal to the table and passing through the edge 15. That portion of the reach 20 is backed by a flat plate 20a.

The roller 19 is rotatably mounted on a support arm 21, which in turn is mounted on the end of a beam 22. The beam 22 is rigidly associated with an arm 23 of a support 24. As may be seen in FIG. 1, the drive roller 18 is carried by an axle 25, which extends through the arm 23 and is driven by a motor 26 through a first pulley 27, a belt 28, and a second pulley 29 fixed to the axle 25. The bracket 24 has a central hub portion 30 which is slidably and rotatably mounted on a guide rail 31 extending across the table 11 and parallel to the edge 15.

Means are provided to drive the support 24 along the guide rail 31 so that the portion 20 of the belt 17 traverses the edge of the sheet 13. Such means comprise a 3 shaft 32 which is provided with acme threads and which is driven by a motor 33 through suitable gears and clutches provided in a casing 34. The acme thread is engaged by a plurality of fingers 35 which are provided on a plate 36 fixed to the hub portion 30.

In order to support the roller 19 and its support arm 21 relative to the front edge of the table, and to maintain a predetermined skivin g angle for the belt 17, there is provided a roller assembly 37. The assembly 37 has a base member 38 which is fixed to the support arm 21 by an arm 39. A shaft 40 projects from the base member 38 and rotatably carries a roller 41. The roller 41 has a relatively small diameter end portion 42 and a larger diameter intermediate portion 43. As the belt 17 and its associated

rollers

18 and 19 are driven from right to left, as viewed in FIG. 1, a rough initial taper is effected as the portion 43 rides along a shelf 44. When the belt 17 reaches the end of its travel past the left side edge of the sheet 13, a limit switch 45 is engaged by a button 46 on the portion 38. When the limit switch 45 is contacted, the clutch which drives the threaded shaft 32 is reversed to reverse the direction of rotation of the shaft 32 to drive the belt 17 to the right. The limit switch 45 also energizes a solenoid 47 so that a rod 48 of the solenoid drives the roller 41 to the left and to the position illustrated in FIG. 3. The roller 41 is retained in the position illustrated by a spring-loaded ball detent 49, which is received within an annular groove 50 in the rod 40.

Since the portion 42 has a smaller diameter than the portion 43, the belt 17 is lowered to provide a fine finish cut during traversal of the belt to the right as viewed in FIG. 1. After the belt 17 traverses the front edge of the sheet 13, the roller 41 rides upwardly along a cam surface 51 to move the belt 17 upwardly away from the table. Another cam plate 52 has fingers 53 which receive and straddle the shaft 40 and which push the roller 41 inwardly toward the table so that the detent 49 engages an annular groove 54 in the shaft 40. In this manner, the roller 41 is in position for a rough cut on another sheet. Further movement of the belt 17 to the right causes a button 55 on the base portion 38 to engage a limit switch 56. When the limit switch 56 is engaged, the

motors

26 and 33 are shut off to stop the shaft and the belt 17. The sheet 13 is then turned over for a skiving operation on its opposite edge.

Although a preferred embodiment of this invention is illustrated, it is to be understood that various modifica- 4 tions and rearrangements of parts may be resorted to without departing from the scope of the invention.

I claim:

1. Apparatus for skiving edge portions of sheet stock, comprising a flat table having a surface adapted to support sheet stock, said table having means to retain an edge of said stock in coplanar relationship with an edge of said table, an endless abrasive belt mounted between a drive roller and an idler roller and having a flat reach extending at an acute angle with respect to the plane of said table, at least a portion of said flat reach overlying and being intersected by a plane normal to said table and passing through said table edge, one of said rollers having at least a portion thereof located below the plane of said table, said roller adjacent said portion of said flat reach being supported relative to the table by a roller which is adapted to roll along a shelf portion of said table adjacent said edge.

2. Apparatus according to claim 1, wherein said supporting roller has a first portion of relatively small diameter and an axially adjacent portion of relatively large diameter.

3. Apparatus according to claim 2, including means to axially shift the position of said supporting roller toward and away from the table so that said large and small diameter portions may selectively roll along said shelf to change the depth of cut by said belt.

4. Apparatus for skiving edge portions of sheet stock, comprising a fiat table having a surface adapted to support sheet stock, said table having means to retain an edge of said stock in coplanar relationship with an edge of said table, an endless abrasive belt mounted between a drive roller and an idler roller and having a flat reach extending at an acute angle with respect to the plane of said table, at least a portion of said flat reach overlying and being intersected by a plane normal to said table and passing through said table edge, said drive roller being rotatably mounted on a bracket having a hub portion, a guide rod passing through said hub portion and being parallel to the edge of said table, a threaded shaft rotatably mounted on said table, means for rotating said threaded shaft, means fixed to said hub portion and engaging the threads of said shaft, a beam extending from said hub portion and having its distal end fixed to a support arm, said idler roller being rotatably mounted on said support arm and having a portion thereof located below the plane of .said table.

Claims

4. Apparatus for skiving edge portions of sheet stock, comprising a flat table havIng a surface adapted to support sheet stock, said table having means to retain an edge of said stock in coplanar relationship with an edge of said table, an endless abrasive belt mounted between a drive roller and an idler roller and having a flat reach extending at an acute angle with respect to the plane of said table, at least a portion of said flat reach overlying and being intersected by a plane normal to said table and passing through said table edge, said drive roller being rotatably mounted on a bracket having a hub portion, a guide rod passing through said hub portion and being parallel to the edge of said table, a threaded shaft rotatably mounted on said table, means for rotating said threaded shaft, means fixed to said hub portion and engaging the threads of said shaft, a beam extending from said hub portion and having its distal end fixed to a support arm, said idler roller being rotatably mounted on said support arm and having a portion thereof located below the plane of said table.