Patent GB-635963-A (GB)
Title: Improvements in or relating to devices for the fully automatic machining of surfaces of blade like work
IPC: B23C3/16
Filed: 1944-09-08
Abstract: 635,963. COPY - milling. RIGID, Ltd. Sept. 8, 1944, No. 17160. Convention date, Aug. 11, 1943. [Class 83 (iii)] [Also in Group XXIX] In a copying milling-machine for producing work of blade-like form such as screw-propellers the work is given an oscillatory movement relatively to a cutter performing a vertical copying movement so that the cutter may pass completely round the work, under control of a pattern and tracer, to machine both sides of the work at the same setting thereof. The machine comprises rotary tables 60, 61 for supporting the work 45 and pattern 44 respectively and vertical standards, 1, 15 for the cutter head 4 and tracer head 19. Two cutters 5 for operating on the upper and lower surfaces of the work respectively may be provided on the head 4 which is axially adjustable by a screw 8 on bracket 3 angularly adjustable on a slide 2 vertically adjustable on the standard 1. Copying movement is imparted to the slide 2 by the piston 50 of a hydraulic cylinder 49 which is supplied at opposite ends with fluid through pipes 46, 47, having branches 46<SP>1</SP>, 471 leading to a tracer-controlled relief valve 39. This valve is carried by a slide 16 vertically adjusted on the standard 15 and carrying an angularly adjustable support 17 for the tracer head 19. Movement of slide 16 is caused by the piston 37 of a hydraulic cylinder 36 supplied with fluid by pipes 33, 34 having branches 33<SP>1</SP>, 341, leading to a relief valve 30 under control of the tracer head 19. The tables 60, 61 are rotated simultaneously by an electric motor 62 and the tool head 4 and tracer head 19 are simultaneously fed radially inwards towards the axes of the work and pattern, after each copying cycle round the pattern, by means of an electric motor 13 driving, through gearing and shafts 11, 27, 25, the screw 8 and a screw 21 on the tracer arm 18. In operation, with the tracer and cutter above the pattern and work, a push button is actuated to de-energize a solenoid 74 on the tracer arm 18 and allow a spring 68 to rock a lever 69 pivoted on the arm at 70 and connected by a rod 31 to the tracer. The lever 69 is also connected to the valve 30 which is thereby displaced to open pipe 34 to the exhaust 35 and close the exhaust from pipe 33 so that the tracer will be lowered towards the pattern. The cylinder 39 moves down with the slide 16 and engagement of a valve plunger 41 with an inclined template 43 opens pipe 47 to the exhaust 48 and cuts off pipe. 46 from exhaust to increase pressure above piston 50 and feed the tool head 4 downwardly. When a tracer roller 20 engages the pattern 44 the lever 69 is swung to restore valve 30 to its central position and stop downward feed of the tracer and cutter and the lever also opens contacts 71, 71<SP>1</SP>, to energize a relay to put the machine under automatic tracer control. A push button is then actuated to start motor 62 and cause rotation of the work and pattern, the undulations of the pattern acting on the lower tracer roller 20 to move the valve backwards and forwards and so raise and lower the cutter and tracer to conform to the shape of the pattern. A rack 59 on the cutter slide 2 engages a pinion on a shaft 57 connected by change-gears 54 to a rack 52 on the support of the template 43 so that the latter will be moved in unison with the cutter slide to tend to restore the valve 41 to its neutral position and so produce a servo-action. When the tracer roller 20 passes off the edge of the pattern, spring 68 swings lever 69 to break contacts 71, 71<SP>1</SP>, and stop rotation of the work and pattern and valve 30 is actuated to cause downward feed of slides 2, 16 until slide 16 engages a limit switch 78 to energize relays which start motor 62 for reverse rotation of the work and pattern. When the pattern begins to overlap the tracer a limit switch 81 is engaged by a stop 80 on the work table to actuate relays for stopping motor 62 and for energizing solenoid 74 which rocks lever 69 to move valve 30 and start an upward feed of slides 4, 16. This action also opens a switch 72, 72<SP>1</SP> to prevent motor 62 from starting. On contact of the lower side of the pattern with the upper roller 20 the upward feed of slides 4, 16 is stopped and contacts 72, 721 are closed to resume the reverse rotation of the pattern and work, during which the lower side of the pattern is copied on the work. When the upper roller 20 passes off the lower edge of the pattern a stop 79 on table 60 engages switch 81 to actuate relays for breaking the circuit to contacts 721, thus stopping motor 62 and starting upward feed of the slides 2, 16. Upward feed continues until the slide 16 meets a limit switch 77 to energize a time relay which causes motor 13 to run for a short time and move the tracer arm 18 and tool head 4 radially inwards for the required feed. The solenoid 74 is also energized to move valve 30 for a downward feed, and a new circuit of the pattern and work commences. Lateral feed of the cutter and tracer may be performed radially outwards instead of inwardly by reversing motor 13 by a hand switch, and any of the machine feeds may be controlled by hand switches. Two or more cutter standards 1 controlled by a single pattern 44 and one tracer head 19 may be arranged around the work table 60 so that a multi-bladed propeller may be produced from the single blade pattern, but in this case the tracer slide 16 carries a corresponding number of servovalves 39 each co-operating with a template 43 actuated by its appropriate cutter slide. The tracer rollers 20 have pointed wings adjustably attached to their pivots to engage the extreme edges of the pattern 44, and when operating on small work-pieces, the tracer and cutter heads may be provided with a single roller and cutter respectively. Varying scale of reproduction.-The vertical scale of reproduction may be varied by altering the inclination of the template 43 and by altering the ratio of the change gearing 54 controlling the horizontal movements of the template. To vary the horizontal scale of reproduction the change-gearing 28 is altered so that different radial feeds will be imparted to the tracer and cutter. Reversing hand of reproduction.-A manually-operated reversing clutch 63 is provided in the drive from the motor 62 to the pattern table 61 so that the work and pattern may be rotated in opposite directions for reversing the hand of reproduction.