GB743275A - Improvements in fluid pressure control arrangements, especially for planing and the like machines - Google Patents

Abstract

743,275. Planing-machine details. KLOPP, F. June 16,1953 [Nov. 19, 1952], No. 16603/53. Class 83 (3). A fluid-pressure control arrangement for the pivoted tool-holder of a planing or shaping machine comprises a control-piston engaging the tool-holder for automatically lifting it during the return stroke, the working pressure for the control-piston being generated by an auxiliary piston, the stroke movements of which are positively controlled in relation to the motion of the ram head, and the pressure impulse from which directly produces the working pressure for the control-piston. The tool-holder 3 is pivoted at 4, upward movement being limited by an adjustable stop 34. A fluid-pressure piston 5 presses against the back of the tool-holder to give relief on the rearward movement of the hydraulically-operated ram 1. Pressure for operating the piston is obtained through a line 9 from an auxiliary piston and cylinder 7, 8, the piston being connected for movement with a main controlvalve 28. Pressure-fluid passes through an adjustable throttle-valve 10 and a ball-valve 12 allows the tool-holder to fall by gravity when the piston 7 moves downwards. A valvechest 17 above the cylinder 8 carries a reliefvalve 14 leading through a pipe 15 to a reservoir 25, and a non-return valve 18 which allows "make-up " fluid from a return part of the main circuit to enter the tool-lifting circuit when the piston 7 is on its downward stroke. A vulcanized-fibre plate 35 is held by a spring 36 against the rear top edge of the tool-holder to reduce shock when the latter is swung against its stop. The ram operation comprises a slide-valve 28 and two further slide-valves 31, 32, the former being a starting control and the latter a preliminary control valve. Automatic feed is effected by a ratchet 37 through rack-and-pinion gearing connected to the valve 28. A shaft 38 is unidirectionally rotated in steps and the motion transferred to a screwed feed-spindle 40 through a reversing gear. An auxiliary high-speed feed drive is provided by a motor 42. The pump 23 for supplying fluidpressure has a control 23a for varying the output and is driven by an electric motor 24.