Patent GB-189921595-A (GB)
Title: Improvements in Turret Lathes.
Inventor: HARTNESS JAMES
Filed: 1899-10-28
Granted: 1900-07-14
Abstract: 21,595. Hartness, J. Oct. 28. Lathes.-A screw machine, adapted also for use in operating on pulleys, cylinder covers, &c., has a wedge-shaped bed a<2>, Fig. 1, carrying a headstock or casing a<4> in which a chuck carrier plate a<8>, Fig. 16, is mounted in circular roller bearings a", and guided centrally on a fixed hub a<7>. The carrier plate is driven by gearing from a shaft a<15>. The turret c, revolubly mounted on a saddle d, has grooves in its surface in which any desired number of toolboxes may be secured. Cylindrical covers d<6>, fixed on the front edge of the saddle and passing freely through apertures in the headstock, protect the slides b from chips &c. The turret is rotated by ratchet gearing operated by a sliding rack d<10> on the saddle. Towards the end of the rear movement of the saddle the rack strikes a bar d<13>, fixed to the lathe bed, and effects the rotation of the turret. During the initial forward movement of the saddle the rack is held by spring latches on the bar to effect the idle ratchet stroke. The turret is locked by two diametrically-opposed spring pins, which are released by a rock-shaft on the saddle when the rack commences to rotate the turret. Adjustable stops, corresponding to the number of tools on the turret, are provided, so that the turret may be rotated one or more steps at one operation should any of the tools be idle. The saddle is reciprocated by fluid pressure. A cylinder f, Fig. 33, in the saddle has a piston f<3>, the rod of which is fixed to a bracket d<14> on the lathe bed. The rod is hollow, and serves to admit fluid to the rear end of the cylinder to withdraw the saddle. A pipe f<4> in the rod admits fluid to the front end of the cylinder to advance the saddle. The fluid is pumped into a valve casing g by a pump with cylinders h, Fig. 41, having a common piston h<6> operated by a rocking-shaft h<9> with a crank arm h<10>. The rocking-shaft is operated through a loose arm h<14> rocked by a crank on a pinion geared to the chuck driving-gear. The loose arm has ratchet teeth engaged by two pawls h<19> on the arm h<10>, so that, by varying the relative angular positions of the two arms, the stroke of the pump is altered, and the rate of feed varied. This is effected automatically by a partial gear h<21>, loose on the rocking-shaft, which can be partially rotated by a rack h<24>, so that the plain part h<22> disengages one or other of the pawls until the remaining pawl has rotated the crank arm to such a position as to allow both pawls to engage again. The valve casing g contains a piston valve for admitting fluid to either end of the cylinder. Notched rods, corresponding to each tool, are secured to the bed, and can be separately engaged with pawls on the saddle when the turret has reached its desired position. This engagement causes a lever to be rocked when the saddle reaches its forward limit which operates the valve to bring back the saddle. When the saddle reaches its backward limit, the valve is again reversed to feed the saddle forwards. An auxiliary pump is used to give a rapid return stroke and initial forward stroke. This pump is controlled by a second piston valve acting in conjunction with the first. The supply from the auxiliary pump aids the main supply during the whole of the return stroke and that part of the forward stroke during which the tool is idle. The auxiliary supply is cut off by a movement of the valve produced by one of a number of adjustable stops. These stops correspond to the tools, and are mounted on a rotary carrier k<10> on a shaft k<8> driven in unison with the turret. The stops act on the valve lever j<15>. The fluid motor for driving the chuck at a constant speed irrespective of the resistance of the work has a wheel m with concentric series of curved blades. The wheel is mounted in a casing m<3>, and is acted upon on opposite sides by jets from nozzles m<4>, m<5>. The nozzles are mounted on a shaft m<13>, so that they may be rocked radially of the wheel to vary the speed. A hand-operated valve m<8> is provided, to admit fluid to one or other of the nozzles to reverse the direction of rotation. The nozzles are automatically rocked by a rotary stop carrier n<2>, rotating in unison with the turret, and having stops corresponding in number to the tools. The stops n<5> engage successively one end of a spring lever n<18> on a slide n<12>, sliding in a casing n<4>, causing a nut section on the other end to engage a thread on the carrier shaft n'. This moves the slide, and operates a chain n<16> attached to a weighted arm on the shaft m<13> to move the nozzles radially outwards until the spring lever slips off the stop. The nozzles are then held in this position while the tool operates, and are returned by the weight when the slide is released by the rotation of the turret and stop carrier. A similar slide p is provided to operate simultaneously the rack h<24> by a chain h<25> to vary the pump stroke and saddle feed. The motor shaft drives the chuck driving-shaft a<15> through one of two pairs of wheels r<1>, r<2>, or r<1>, r<3>, the desired pair being engaged by a clutch r' and lever r<5>. The lower end of the lever is operated by a cam sleeve r<8>. The cam surfaces on the sleeve can be engaged by either one of four plungers in a casing s', which serve to move it from the mid position to the right or left or vice versÔ, thus connecting either pair of wheels or throwing both out. The plungers are normally held out of engagement by spring pawls which are independently released as desired by a stop carrier rotating in unison with the turret and feathered on the shaft k<8>, carrying the stop carrier k<10>. A cam surface on the sleeve serves to return the plungers.