Patent GB-745969-A (GB)
Title: Improvements in or relating to shoe assembly for rubbing machine
IPC: B24B23/04
Filed: 1954-01-13
Abstract: 745,969. Rubbing machines. SUNDSTRAND MACHINE TOOL CO. Jan. 13, 1954 [Jan. 26, 1953], No. 986/54. Class 60 A rubbing machine comprises a generally rectangular housing A and a shoe B mounted for orbital movement with respect to the housing. The housing is shaped to fit within the palm of the user's hand thus permitting an easy gripping of the unit, and has an air inlet and coolant fluid inlet. The shoe assembly B comprises a shoe 10 to which sheets of abrasive material 11 are attached by manually operable clamps each comprising a lever 12. A yielding backing for the abrasive material is provided by a rubber pad 27 secured to the underside of the shoe. The shoe assembly B is actuated by a vane type motor 43a; compressed air from the inlet travels through passages within the housing to a valve chamber 30 containing a valve 32. The valve is urged to closing position by a spring 35 and is opened by depressing, by the palm of the user's hand. a cover 1 pivotally mounted -on the housing by pin 2. Air then passes through chamber 36. a passage in the housing, an internal recess 40 in the body of the housing, the interior of a drive shaft 41, openings 42 in the drive shaft, an annular chamber 43 and finally an inlet port plate. A centrifugal speed governor actuates a sleeve 51 which controls the flow through the openings 42. The housing is formed with a bottom plate 60 having downwardly turned sides 61 and inturned ends 62 forming guide tracks. The shoe assembly B includes a pair of shoe-supporting members comprising tubular members 63 each having a square block 64 at its closed end: each member 63 is open at its opposite end and slidably receives therein a plunger 65 to the exposed end of which is attached square block 66. A coil spring 67 positioned between the solid end of the tubular member 63 and the plunger 65 urges the blocks 64, 66 against the sides 61 of the plate 60 forming the guide tracks. The shoe 10 is slidably mounted unon the tubes 63 by upstanding arms 67' located at the four corners of the shoe, the tubes 63 passing through openings in the arms 67<SP>1</SP> lined with bearing material 68. The shoe travels in an orbital path, the movement being the resultant of two components of movement; the movement of the shoe supporting members along the guide tracks produces the first component of movement, the other component of movement being produced by the sliding movement of the upstanding arms 67' along the shoe supporting members. To actuate the shoe, drive shaft 41 has an eccentric end 70 rotatably mounted within an upstanding annular flange 71 of the shoe 10, with the interposition of a thrust ball bearing 72; the drive shaft is supported in the housing by thrust ball bearing 73. For dynamic balancing of the drive shaft, a counterweight 74 is secured thereto by bolt 76. Strips 80 of suitable material are positioned between the inturned edges 62 of the guide tracks and the top face of the shoe 10 and strips 80a secured to the front and rear edges of the shoe are in sliding engagement with the underside of the bottom 60 of the housing. A cover plate 81 is fastened to the shoe 10 by screws 82. Coolant from the inlet passes through valve chamber 83, chamber 89, passage 90 and outlet pipe 91; control valve 84 is opened, against spring 86, by the movable cover 1. In a modification the square blocks on the ends of the shoe supporting members are replaced by rollers which engage the plate 60 and inturned edges 62; needle bearings are employed for journalling the drive shaft in the housing and the eccentric end of the drive shaft in the shoe