GB1272064A - Device for working a cylindrical work-piece - Google Patents

Abstract

1,272,064. Sawing. A. E. R. ARNOT. 22 April, 1969 [22 April, 1968], No. 18992/68. Heading B5L. [Also in Division B3] A device for working a cylindrical workpiece comprises a frame, workpiece bearing means carried by the frame, a tool holder mounted on the frame and arranged to carry a saw blade for working the workpiece and a feeding mechanism arranged to derive a drive from a rotary drive derived from relative rotation between the workpiece and the device to effect feeding movement between the saw and the workpiece. As shown, a pipe-cutter device comprises a tool support 20, carrying a saw blade 23, pivoted on a frame 22 at 21. The frame supports rollers 25, 26 for engaging the pipe P to be cut and the relative positions of the support 20 and frame 22 are determined by a screw 41 which is screwed into an arm 39 of a bell crank lever 37 pivoted on the pin 21. The roller 26 is knurled to receive frictional drive from the pipe P and is formed with a cam 29. A one-way roller clutch 31 is mounted on a shaft 30 journalled in frame 22 and a roller 33 on the free end of an arm 32 fixed to the clutch forms a follower for cam 29, a spring 34 attached to the frame 22 and to a lug 35 on the clutch casing biasing the roller into engagement with the cam. Pinned to the shaft 30 is a snail cam 36 so that oscillation of the arm 32 due to the cam 29 causes the clutch 31 to oscillate and the snail cam to be rotated incrementally. The bell crank arm 38 follows the cam 36 and integral with the cam 36 is a knurled ring 44 with a curved cut out 45 which lies flush with a recess 46 in the frame 22 when the ring is turned so that the arm 38 lies against the minimum radius of the cam 36. Relative rotation between the pipe and the device may be manual, a handle H being provided for rotating the device, or as shown by drive from an electric drill via a transmission unit. In operation the pipe P is inserted in the tube 12 and the pipe cutter in its most open position placed over the pipe projecting from the tube 12, screw 41 being loosened, if necessary. The screw 41 is then tightened to clamp the cutter on the pipe and the tongues 18 are engaged in slots 17. An electric drill then drives the cutter round the pipe. The rotating roller 26 causes the cam 36 to rotate in small steps deflecting the bell crank arm 38 and causing the bell crank arm 39 and thus the saw blade 23 to move radially inwards. The roller 25 has a smooth hardened surface which flattens any ridge formed during cutting. The inward feed rate of the blade 23 may be varied by making the effective length of arm 32 adjustable. The inward feed drive may alternatively be derived from rotation of the saw blade itself or of an auxiliary band or roller passing round the pipe. The rollers 25, 26 may be replaced by anti-friction bearing material. One or both of the rollers may be replaced by cutting wheels and the cam 29 by a multi-lobe cam to produce cutter oscillation through say, only 60 degrees. Drive from the roller 26 or the saw blade may be transmitted to the feeding mechanism through a cam, gear, screw, hydraulic or friction drive. The workpiece may be solid.