Patent GB-684961-A (GB)
Title: Improvements in or relating to machines for sanding, rubbing down or polishing surfaces
IPC: B24B23/04
Filed: 1949-11-02
Abstract: 684,961. Rubbing machine. TAYLOR, WOODROW PLANT CO., Ltd., and LABRUM, K. S. Feb. 2, 1951 [Nov. 2, 1949], No. 28110/49. Class 60. [Also in Group XXVI] A hand tool for use in rubbing down a surface comprises a body having a rubbing face, a handle by which the tool may be held, a guide member rigidly associated with the body, an actuating member carried by the guide member for reciprocating movement relatively to the body and.means adapted to produce alternating forces acting between the actuating member and the guide member to give to the said members complementary reciprocating movements whereby the body carrying the rubbing face is reciprocated over the surface, the handle being movably-connected with the body to allow the reciprocation of the latter relatively to the handle. The tool comprises a hollow casing 1 within which is mounted a cylinder 2 secured thereto by screws 3; the cylinder 2 has two pairs of laterally-extending feet 4 to which is secured, by screws 5, a base plate 6. A block 7 e.g. of sponge rubber is secured by adhesive to a backing plate 8 provided with studs 9 tightly engaging holes 10 in the base plate 6; the plate 6 has lips 11 to engage the ends of the backing plate 8. For detachably securing a sheet of sand paper, emery cloth or other rubbing down material over the pad 7, the base plate 6 has ribs 12 the upper edges of which are spaced from the lower edges of the ends of the casing 1 so as to leave slots for insertion of the ends of the sheet. At each end of the casing 1 a roller 13 is provided supported by pins 14 journalled in the sides of the casing 1; one pin of each roller carries an actuating knob 15; the pins 14 are mounted eccentrically on the ends of the rollers 13, so that the surface of the roller can be caused to bear against a strip 16 e.g. of hard rubber, on the base plate 6 so as to grip the end of the sheet. To facilitate fitting of the sheet, the ends of the casing have arcuate cut-away portions 17. The cylinder 2 contains a piston 18 comprising two heads 21, 22 joined by a neck the heads being of different diameters to ensure selfstarting. The cylinder has an inlet port 24, exhaust ports 26, 27, transfer ports 28, 29, connected by passage 32, and transfer ports 30, 31 connected by passage 33. The tool is provided with a handle 34 mounted on a stem 35 secured by screws 36 to a plate 37 mounted on the casing 1. The plate 37 is received between two pairs of projecting lugs 38 formed on the top of'the casing, and is retained in position by two bridge pieces 39 attached to the lugs 38 by screws 40; relative movement between the handle 34 and casing 1 is limited by the engagement against the lugs 38 of bars 41 secured to the edges of plate 47. The handle 34 and stem 35 have air passages 42, 43 leading from an air supply connection 44 at one end of the handle to a recess 45 formed in the underside of the stem 35; the recess is surrounded by a rubber washer 46 pressing on a metal washer 47 fitted in the plate 37. Flow of air through the passage 42 is controlled by a valve in the handle 34, the valve comprising a ball 48 mounted in the enlarged end portion 49 of the passage 42, and forced by the air pressure against a seat 50 to cut off the supply; the ball 48 then projects into a valve chamber 51 in which is slidably mounted a spool 52 urged upwardly by a compression spring 53. The spool 52 has a stem 55 passing freely through a hole 56 and extending into a recess 57; an actuating knob 58 is screwed on the stem 55. The spool 52 has a circumferential recess 59 so that when the spool is in its upper position the ball valve 48 can engage the seat 50; when the knob 58 is depressed the spool 52 forces the valve 48 off its seat and air is admitted. When air is admitted, the piston 18 is caused to reciprocate in the cylinder; since the piston is purposely made of considerable weight, the reaction forces produced cause the cylinder and the remainder of the body of the device, including the casing 1 and the base 7 to reciprocate at the same frequency as the piston but in the opposite phase. The piston could be operated electromagnetically, e.g. by solenoids at opposite ends of the cylinder and controlled by contacts; alternatively, the piston could be reciprocated by an electric or other motor through suitable mechanism.