US2683337A - Paper clamping device for sanding machines - Google Patents

Description

July 13, 1954 s, sc 2,683,337

PAPER CLAMPING DEVICE FOR SANDING MACHINES Original Filed May 24, 1951 PIE. 1

Patented July 13, 1954 UNITED STATS ATENT QFFICE PAPER CLAMPING DEVICE FOR SANDING MACHINES Illinois Original application May 24, 1951, Serial No.

Divided and this application December 27, 1951, Serial No. 263,633

3 Claims.

This invention relates to sanding and polishing machines, and more particularly to an improved and simplified device for clamping the free ends of a sheet of polishing or abrasive material to the plate of a machine.

In portable sanding machines it is necessary to change the abrasive sheets frequently, and the primary object of the present invention is to provide a light, inexpensive and reliable clamping device to facilitate this change. It will be understood that the same clamping device can be used to hold a polishing cloth, or other strip of material, if desired.

The present application is a division of my application Serial No. 228,043, filed May 24, 1951, entitled Rubbing Machine.

The invention is illustrated in a preferred embodiment in the accompanying drawings, in which Fig. l is a side elevational view of a machine embodying the invention; and Fig. 2, a top plan view of the same.

In the embodiment illustrated, a supporting plate 3 is surmounted by a bell-shaped housing 4, in which is mounted an electric motor which receives power from wires 5 connected to a switch 6. The sanding machine has a top 7, provided with a handle 8 and a front knob 9. The motor imparts an orbital motion to a driven plate l9, which is provided at opposite ends with bearings II for the trunnions of the clamping member. The lower sides of the bearings are closed by a metal plate [2, which is secured to the driven plate It by means of screws, not shown. The plate 12 has on opposite sides an upwardly extending lip or projection I3.

Preferably, a soft rubber pad is is cemented to the bottom side of the plate l2, and forms a cushion for a sheet of sandpaper I5 whose free end portions i5 extend around the ends of the plate 12. The ends are held by a pair of similar clamping members which preferably are made of resilient wire and have trunnions l1 journalled in the bearings ll. Each of the members has an offset gripping portion [8 between the bearings H, which may be turned to gripping position by means of a lever arm [9, provided at its end with a finger loop 20. To release one of the clamping members, it is merely necessary to lift the arm I9 over the projection 13 and permit the offset portions l8 to swing up so as to release the ends of the sandpaper strip.

After a fresh strip of sandpaper has been positioned under the plate, its ends may be turned upwardly and inwardly, and the clamping mem- 2 bers brought back into the gripping position shown in Fig. 1. If the pad M is compressed by pressure on the top of the sander while the clamping members are being engaged, the sandpaper strip will be held under a slight tension after the pressure is released.

The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood thereform, for some modifications will be obvious to those skilled in the art.

I claim:

1. In a rubbing machine of the character set forth: a rectangular driven plate for a strip of abrasive material, said plate having a pair of spaced bearings near the corners of one edge portion; a resilient wire transverse clamping member pivotally mounted in said bearings and having an outwardly offset portion between the bearings for gripping one end of a strip of abrasive material against the top of the plate, said member having an integrally formed resilient manually operable crank outside of one of the bearings for torsionally pressing said oifset portion into gripping position; and fastening means on said plate for releasably holding said crank in torsion applying position.

2. A device as specified in claim 1, in which the fastening means comprises an upwardly extending projection on said plate over which the crank arm may he sprung in gripping position.

3. A device as specified in claim 1, in which the plate has an additional pair of bearings near the opposite corners of said plate and upwardly extending projections at the edges of the plate, a second similar wire clamping member is mounted in said bearings for gripping the other end of the strip of abrasive material, and the cranks extend along opposite sides of the machine and are adapted to snap over said projections.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 734,953 Reissmann July 28, 1903 824,981 Domagola July 3, 1906 1,320,596 Aoki Nov. 4, 1919 71,415,171 Gustafson May 9, 1922 2,242,545 Randolph May 20, 1941 2,404,486 George June 11, 1946 2,434,581 Ottoson Jan. 13, 1948 2,475,476 Champayne July 5, 1949

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