Patent GB-462327-A (GB)
Title: Improvements in metal cutting machines for copying or reproducing
IPC: B23Q35/18
Filed: 1935-09-07
Abstract: 462,327. Fluid - pressure servomotor - control systems. RICHARD, C. C. Sept. 7, 1935, No. 24950. [Class 135] [Also in Group XXII] In a copying-machine in which a tool head and a tracer head traverse the work and the pattern respectively in fixed paths, a closed hydraulic circuit maintains a fixed relationship between the tool and tracer, the tool being held under hydraulic pressure until actuated through movement of the tracer towards or away from the work. In the application to a planing machine, Fig. 1, which may be embodied in an attachment, an arm 1 secured to the tool slide 2 moving on the cross rail 96, carries a cylinder 8, connected to a vertical slide 6 on which the tool 3 is mounted. The arm 1 is formed with an arm 10 which extends rearwardly and supports the tracer assembly 12 having a tracer point 13 coacting with the pattern 14. The tracer assembly includes a cylinder 12, Fig. 5 similar to the tool cylinder 8 and the upper and lower ends of the cylinders are respectively connected by pipes 18, 19. By this arrangement upward movement of the piston in the cylinder 12 produces corresponding downward movement of the piston rod 9 so that the tool 3 planes a profile which is inverse to that of the pattern. By cross connections 20, 26 between the pipes 18, 19 the discharge from the upper part of cylinder 12 may be directed to the lower part of cylinder 8 so that, as shown the tool reproduces the shape of the pattern. The work and pattern are mounted on the reciprocating planer table and the slide 2 fed along the rail 96 in the usual way. In order to vary the scale of reproduction the cylinder 8 may be larger or smaller than the cylinder 12. A pump 97 delivers fluid to a pressure line 39 connected to the chamber 34 of the tracer element and a gravity tank 42 may be used to fill the cylinders 8, 12 through shut-off valve 31. A return line 33 from casing 34 leads back to the tank and communicates with the head of cylinder 38. The tracer element consists of a casting 40 connected to an upper cylinder 41. The lower part encloses a fixed head 42 which has a slotted flange through which pass arcuate portions of a cylindrical tube 45 connected to the tracer 13. The central part of the tube is welded to the casing 34 and is provided with high pressure ports 51, 52, Fig. 4, and low pressure ports 54, 59, which coact with chambers 48, 50 in the casing. These ports co-operate with a piston 55 connected to a lower rod 56 and an upper rod 15a which passes through glands 59, 16 and is secured to the piston 36 of the cylinder 12. The piston 55 is in its neutral position, in Fig. 4, and both high pressure and low pressure ports are closed. If the tracer point is lowered, low pressure ports 54, are opened to the lower side of the piston while high pressure fluid flows through port 51, piston port 62 of the upper side of the piston which then moves downwards together with piston 36 until the ports are again closed. This will occur when the movement of the piston just equals the tracer movement. Similarly if the tracer is raised, the piston 36 is immediately raised to the same extent by high pressure fluid and similar movement occurs in the tool control cylinder 8. The tracer is maintained in contact with the work by light pressure through low pressure fluid admitted to chamber 95 and acting on the top of the tube 45. In the application to a lathe, Fig. 3. the work 82 and pattern 81 are mounted coaxially and rotated together and the tool control cylinder is connected as before to the tracer cylinder 75 the rod of which in this form is connected to the tracer cylinder 77 by an arm 79. The tool and tracer move in opposite directions. An adaptation to a milling machine is also described.