Patent GB-1033716-A (GB)
Title: Improvements in or relating to the dividing of tubes and other hollow bodies
Inventor: PAYNE KENNETH MALCOLM
IPC: B23D47/10
Filed: 1964-05-14
Abstract: 1,033,716. Sawing. T.I. (GROUP SERVICES) Ltd. May 12, 1965 [May 14, 1964], No. 20079/64. Addition to 902,542. Heading B5L. A machine for sawing tubes comprises a power-driven saw 10, a tube-holding clamp 11, a pneumatic piston-and-cylinder device 17 for displacing the tube to effect relative movement between the saw and clamp, and an hydraulic clamping device 17 which controls the relative movement so that it is higher whilst the saw is cutting through the intermediate portions of the tube than whilst it is cutting through the first and last portions. The saw 10 is mounted on a stationary axis and driven by an electric motor, and the clamp 11 is mounted on a slide 12 and has a movable jaw 13 connected by a rod 14 to the intermediate part of a lever 15. The lower part of the lever is pivoted to a part of the clamp 11 and the upper part is connected by a piston-rod 16 to the piston of the pneumatic device 17 which is coaxial with the hydraulic clamping device 18. When the device 17 is operated, the jaw 13 is pivoted to clamp a tube to be cut and the clamp then moved along the slide to present the tube to the saw. The hydraulic damping device 18 has a piston mounted on the rod 16 of the pneumatic device, and opposite ends of the device 18 are connected to respective ports 28, 29, Fig. 2 (not shown), in a control cylinder 21 mounted on the device 18. The cylinder contains two control pistons 19, 20, each of which is urged outwardly of the cylinder by a spring 22, 23 and is movable inwardly against the spring pressure by an abutment 24, 25 mounted on an extension 26 of the rod 16. Each piston is formed with an annular groove connected by passages in the piston to the space between the pistons. In operation, when the clamp 11 is in its retracted position, the piston 19 is in its outermost position and the piston 20 is moved by its associated abutment 25 to its innermost position. When the clamp is advanced to first grip the tube and then carry it to the saw, the ends of the device 18 are interconnected by the fluid from the ends of the device passing through ports 28, 29 and the annular groove and passages in control piston 20. As the clamp advances, the outer portion of piston 20 restricts flow of fluid from end to end of the device 18, the fluid flowing through a by-pass passage having a variable restriction to slow the speed of the clamp while the first portion of the tube is sawn. Thereafter the pistons are clear of the ports to permit rapid movement of the clamp while the intermediate portions of the tube are sawn and until the abutment 24 moves piston 19 so that its outer portion restricts flow through port 28 while the final portion of the tube is sawn. When the groove on piston 29 is aligned with port 28, the clamp again resumes its rapid advance until the device 19 is operated to reverse the movement of clamp 11 at a rapid speed, the damping device not then being operated. In alternative embodiments, the saw may be moved and the path of movement may be arcuate.