Patent GB-429161-A (GB)
Title: Improvements in polishing machines
IPC: B24B21/12
Filed: 1934-12-14
Abstract: 429,161. Polishing metal sheets. SKERRETT, H. N., 24, Temple Row, Birmingham.- (Philippi, T. F. ; East St. Louis, Illinois, U.S.A.) Dec. 14, 1934, No. 35898. [Class 60] A machine for polishing flat metal sheets comprises means for carrying the sheet beneath a number of polishing units, each unit comprising a polishing belt pressed on to the sheet and reciprocated across the sheet. The machine comprises a framework built up of base members 1, 2, 3, uprights 4, 5, 6 and connecting members 7, 8 and at each end of the framework is a shaft 10 carrying sprockets 11 on which are mounted endless chains 12 carrying cross members 13 to form a conveyer belt for the work ; rollers 14 and rods 15 support the reaches of the conveyer. The uprights 4 .. 6 carry horizontal angles 16 carrying strips 17, which form tracks for the rollers 21 of carriages B having thereon plates 22 supporting a cross shaft 23 having thereon a lever structure 24, 27, 30 supporting at one end a polishing unit C, and at the other end an electric motor 25, which nearly counterbalances the unit C. The unit C comprises a member] 31 carrying at its front end a pulley 32 and at its rear end a pulley 33 supporting an endless polishing belt 34, the pulley 33 being carried by a shaft 39 driven through a belt 41 from the motor 25 ; the pulley 32 is mounted on a shaft 46 projecting eccentrically from a pin 45 in the member 31 acted on, through a collar 47 and a chain 49, by a spring 50 serving to tension the belt 34. The belt 34 is pressed down on the work by a buffer wheel 52 comprising a number of separate cloth discs 54, and the member 31 carries a pin 58 to receive weights 59 to regulate the pressure of the belt on the work ; a hood 60 and a dust pipe 61 leading to a suction fan are provided. The polishing belt comprises a canvas backing 64 and an outer portion 65 of felt &c. with bevelled edges 66, or in a modified form may comprise laminations or layers of endless woven fabric, such as cotton sheeting sewn by lengthwise lines of stitching, the edges of the operative face being rounded off by the insertion of narrower layers ; the operative face has applied thereto an abrading compound. Each carriage B is movable to and fro across the work by a sprocket chain 67, the ends of which are connected to the carriage and which passes over a sprocket wheel 68 at the front of the frame and a sprocket wheel 69 secured to a shaft 70 at the rear of the frame. The shaft 70 also carries a reversible clutch device having one of its drums 72 connected by a belt 73 to a shaft 74, and its other drum similarly connected to a shaft 75 geared by pinions to the shaft 74, which is driven by a belt 78 through variable speed gearing 80 from a motor 82, which also drives one of the shafts 10 to move the work conveyer. The carriage B is caused to reciprocate across the work by operation of the clutch through a lever actuated by a rod 84, on which are mounted adjustable collars 85 with abutment members 87 engaged by a pin 89 on an arm 88 on the carriage ; the rod 84 also may be held with the clutch in neutral position by a pin 93 which may drop between a handle 90 and a collar 92 on the rod. In order to change an abrading belt, the carriage B may make an extended forward movement and then stop, this being achieved by the use of an auxiliary abutment member 97 on the rod 84, and a cam member 99 which causes the arm 88 to rise on a forward stroke, so that the pin 89 misses the abutment 87 but engages the member 97; the cam member 99 is slidable on shafts 100 into and out of operative position and has a latching device normally holding it in inoperative position. The work is held down on the conveyer by rollers 105 on shafts 106 carried by slidably mounted blocks 107 and held down by springs 111 on screws 109 so that the rollers may move upwardly to allow the work to pass under them. Between adjacent polishing units C are work guide members 112, 113 mounted adjustably on the shafts 106 and provided with rounded end portions to guide the work beneath the rollers 105 ; the members 113 also carry, in parts 116, guide blocks 117 set at an angle and having at their lower ends foot plates 118 contacting at their front edges with the conveyer, and at the front of the conveyer are guide members with inclined end parts facing the direction of travel of the work.