GB323555A - Improvements in or relating to copying-lathes - Google Patents

Abstract

323,555. British United Shoe Machinery Co., Ltd., and Bonser, E. F., (United Shoe Machinery Corporation). Oct. 9, 1928. Turning.-A copying-lathe such as a lastturning lathe of the type described in Specifications 20914/03 and 221,823 has means controlled bv the reversals of the pattern carrying frame to vary the pressure between the pattern and its tracer so as to minimise jarring. In one form an air-check cylinder 10 is mounted on the swing frame of the lathe described in Specification 221,823. The cylinder has a piston 12 fitted with a hollow extension 14 pressed by a spring 20 against a profiled plate 50 mounted on the cuttercarriage 55. The cylinder communicates by pass. ages 26, 28, with a passage 30 which may be partially shielded by means of a sleeve 32 adjusted by a screw 34. A non-return ball-valve 44 is provided to admit air to the cylinder behind the piston while a passage 44 is provided to admit air to the cylinder behind the piston while a passage 42 is bored in the front cylinder cover. In order to vary the checking action along the length of the last, the abutment plate 50 is shaped as shown in Fig. 2, the action being at a maximum while the greatest variations of the radial dimensions of the last are occuring. In a modification, adapted to be used with a Gilman lathe, the swing frame 60 is pulled towards the cutter carriage by a rope 64 carrying a weight 62 and passing over a fixed pulley 66 and a second pulley 70 mounted on one arm of a bell crank connected by a link 72 to the frame. In this form, when the swing frame makes a sudden outward movement the pulley 70 is raised, thus increasing the pull of the rope 64 and preventing the frame from leaving the model. Conversely when an inward movement is made, the pull is decreased and the cutter is prevented from cutting too deeply into the work. In a further modification the rope may be replaced by an elastic member which is engaged at some point in its length by the pulley 70 to vary the pull on the swing frame. In another modification the swing frame may be biassed by means of a member 81, Fig. 5, engaging the model at a point opposite to the tracer wheel 93 and pressed into contact with the model by means of an adjustable spring 88.