Patent GB-814793-A (GB)
Title: Rubbing machine
IPC: B24B23/04
Filed: 1957-09-13
Abstract: 814,793. Rubbing machines. SUNDSTRAND MACHINE TOOL CO. Sept. 13, 1957 [April 24, 1957], No. 28870/57. Class 60. A rubbing machine comprises a rubbing shoe, a power driven motor above the shoe, shoe supporting spaced spring means extending between the motor and the shoe and distortable laterally to provide lateral movement of the shoe relative to the motor, means for maintaining the spring means under compression at all times, a motor shaft rotated by the motor having one end extending toward the shoe, an eccentric on the shaft journalled in the shoe to cause orbital movement thereof against the resistance of the compressed spring means upon rotation of the motor shaft, a flexible dust enclosure extending between the motor and the shoe and surrounding the spring means and the eccentric, and means for attaching the dust enclosure to the shoe. The rubbing shoe 10 is mounted for orbital movement relative to a housing 11 forming part of a rotary vane-type pneumatic motor 12; pressure air supplied to the inlet 15 passes to the motor under the control of a normally-closed valve 16 opened by depression of a pivoted part 13 of the housing by the operator's hand. The upper end of the motor shaft is journalled in a bolt bearing 24 pre-loaded by a spring 25 and has secured thereto a counterweight 23. The lower side of the housing has a flange 26; coplanar with the flange is a closure plate 27 with a circular flange 27a housing the lower bearing 28 for the motor shaft 20. The lower end of the shaft 20 beneath the bearing 28 has a circular enlargement 20a to which is attached a counterweight arranged oppositely to the upper counterweight 23 so as to provide dynamic balance. The end of the shaft beneath the enlargement 20a is formed as an eccentric 29 rotatably supported in a double-row ball bearing 30; the lower end of the eccentric 29 is locked within the bearing by a tapered plug 31 threaded into the lower end which has slots 29a. The rubbing shoe assembly comprises a rectangular plate 35 with a depressed centre portion 35a, a depressed centre well 35b and elongated ribs 35c, the plate has moulded thereto a block of resilient rubber 36 to the bottom surface of which is attached a resilient pad 37 of felt, sponge rubber &c. A strip 38 of sandpaper or the like is arranged along the bottom of the shoe with the ends of the strip held by releasable clamps 39 mounted on the ends of the plate 35. Within the centre portion 35a of the plate 35 is a plate 42 with a central circular opening surrounded by a downward flange 42b; in the opening is secured, e.g. by soldering, an upwardly extending sleeve 41 which is a press fit around the bearing 30. The shoe assembly 10 is held spaced from the housing 11 by four helical springs 43. Each spring has its upper end attached to a threaded stud 44 held in the base flange 26, e.g. by a rivet. The lower end of each spring 43 is held by a threaded stud 46 held in position by a bolt 47 having its head within a well 37a in the pad 37; the bolt extends upwardly through the plates 35, 42 to engage a downward extension of the stud 46, the parts being so proportioned that the springs 43 are always under compression. Dust is excluded by a flexible member 48, e.g. of rubber, having holes 48a in its ends for the discharge of air. The lower edge of the member 48 has an inward flange 49 located between the plates 35, 42; the upper edge of the member 48 has a lip 48b arranged to snap over an upward flange 50a of a base plate 50 extending beneath the base 26 of the housing 11.