Patent GB-686363-A (GB)
Title: Improvements in or relating to rubbing machine and demountable rubbing means thereof
IPC: B24B23/04
Filed: 1951-06-08
Abstract: 686,363. Rubbing machines. SUNDSTRAND MACHINE TOOL CO. June 8, 1951 [July 14, 1950], No. 13628/51. Class 60. [Also in Group XXII] A reciprocatory rubbing machine has a demountable shoe which can be readily removed and replaced with a shoe of similar construction in a much shorter time than is necessary to replace the abrasive material on the shoe. A rubbing machine comprises a hollow body member 20 to the lower portion of which is attached a reciprocatory member 21 formed to receive a demountable shoe member 22 having a rubber pad 23 which provides a resilient backing for a sheet of abrasive material 24 held to the shoe 22 by clamping means provided at each end of the shoe. The body is provided with a channel member 26 having inturned bottom flanges 27 on which roll wheels 28 mounted on the reciprocatory member 21. The latter has flange portions 29 underlying the flanges 27. A drive shaft 30, driven by a motor, e.g. an air motor, enclosed in the body member, carries oppositely facing eccentrics 31, 32, operating through connecting rods 33, 35, a counterweight 34, slidably mounted in the channel members 26, and the reciprocatory member 21. The latter has at one end a pair of inclined slots 36, 37 and at the opposite end an arcuate dovetail 42. The shoe 22 comprises a flat plate 44 having at one end a pair of upstanding lugs 45, 46 the faces 47, 48 of which are wedge shaped; a plate 50 secured to the other end of the shoe has an arcuate undercut portion 52. Brackets 55, 56 on the plate 44 support a rod 57 engageable by a hook portion 58 of a catch 59 attached to the reciprocatory member 21. A lever 60, having a handle portion 61, is rotatably mounted on a shaft 62 at one end of the reciprocatory member and carries cam portions 65 adapted to engage the underside of the catch 59 when the handle 61 is swung upwardly. To retain the catch in position there is secured thereto a bracket 66 having a slot 67 through which the shaft 62 extends; thus the catch is loosely mounted on the reciprocatory member and is free to move in the slot 67 upwardly and downwardly with pivotal movement of the lever 60. The central portion 68 of the outer end of the catch 59 is bent inwardly to engage a shaft 69 secured to the side pieces 60a, 60b of the lever 60, thus limiting the forward movement of the lever 60 when the clamp is disengaged. To mount the shoe on the reciprocatory member, the dovetail 42 is inserted into the undercut portion 52 of plate 50; the shoe is then swung upwardly about the engaged dovetail and plate as a pivot until the lugs 45, 46 enter the slots 37, 36. At this point the hook 58 of catch 59 is just under rod 57 and by swinging the handle 61 upwardly the hook engages the rod to force the shoe upwardly against the bottom of the reciprocatory member. The sides of the slots 36, 37 engage the wedge faces 48, 47 of the lugs to shift the shoe slightly to the left to wedge the slanting face of the dovetail 42 into the undercut portion 52. Longitudinal slippage between the parts is prevented by the dual wedging action of the wedge faces 47, 48 on the lugs and the wedge faces on the dovetail and plate. The inclined arrangement of the lugs and slots prevents transverse slippage between the parts. Clamps 70, 71 are provided at each end of the shoe 22, each having a clamping face portion 72 extending substantially the entire width of the shoe and adapted to press the sheet of abrasive material 24 into frictional engagement with a recess 74 at each end of the shoe. The clamps are rotatably and removably mounted about pins 75 mounted in pairs of brackets 76 fixed to the plate 44. Each clamp has at each end a pair of parallel lever arms 77 extending inwardly and downwardly therefrom, the inner arm of each pair of lever arms having a slot 77a receiving the pins 75. Thick elastic bands 78 are stretched between the pairs of lever arms at opposite ends of the shoe; pins 80 extend through holes in the rounded end portions 79 of the bands and through matching openings in each pair of lever arms. Each clamp has a pair of finger actuating portions 81 to rotate the clamp to lift the portion 72 away from the recess 74 to permit insertion of the ends of the abrasive material 24. On release of the finger pressure the tension of the bands 78 brings the clamping edge 72 of the clamp against the abrasive material to hold it in the recess.