GB190202725A - Improvements in Machine Tools - Google Patents

Abstract

2725. Roberts, D. Feb. 3. Milling; tables, machine-tool.-The table of a machine tool is provided with a revoluble upper plate or cylinder on which the work is secured, the plate being automatically unlocked, rotated, and locked after each return stroke of the table, or of the tool if the table is stationary and the tool is traversed, to present a fresh surface of the work or a separate article to the operation of the tool. The invention is described with reference to a milling - machine in which the cutter b is rotated by gearing c and the table f traversed by a screw g. The screw is driven at a quick-return speed by wheels k', k<1>, k and at a slower feeding-speed by worm gearing i<4>, i<1> from a shaft h geared to the pulley shaft d. The wheels k', i<4> are loose on the screw and are alternately coupled to it by a clutch operated by a tappet rod m and pin n on the table. As the table approaches the end of its return stroke, a lever p<1> pivoted on it at p rides over an inclined stop q on the bed, the lever p<1> and an arm r connected to it being raised, and thus disengaging the long end r<1> of a bell crank pivoted on the arm r from a pin r<2> on a worm-wheel r<3>. This disengagement allows the toothed end of a sleeve s<3>, with which the short arm of the bell crank engages, to be pressed by a spring s<1> into engagement with a clutch member s<2> o the e shaft h. The other end of the sleeve has a worm s<4> engaging the worm - wheel r<3>, the spindle r<4> of which has at its upper end a disc t with a pin t'. The engagement of the clutch s<2>, s<3> rotates the disc, causing the pin t<1> to operate a lever u to disengage a locking- bolt v from the work plate e and afterwards, to enter a notch in a disc x on the pivot of the plate, to rotate the plate the desired fraction of a revolution. The period of engagement of the worm gearing s<4>, r<3> is determined by the length of the stop q, which may be varied to cause the plate to be rotated by one or more notches. The plate is provided with clamping-devices (not shown) to secure the work.