GB596189A - Improvements in methods of and machines for thread rolling - Google Patents

Abstract

596,189. Boiling screw-threads. WATKINS, D. M., and DILKE, W. E. July 24, 1945, No. 18956. [Class 83 (iv)] In a method of rolling screwthreads on to blanks in which the blanks are fed transversely into and through the gap between a pair of threaded rolls held at a fixed distance apart and one of which moves at a slightly greater surface speed than the other, one of the rolls is held against longitudinal movement, while the other is held in the correct longitudinal position for starting thread-rolling until the blank is gripped and this roll is positively displaced longitudinally for ejecting the threaded blank by pressure on the flanks of the screw-threads when the blank has reached the centre of the gap between the rolls. The machine comprises a base casting 10 supporting an upper casting 11 carrying the main operating parts. An electric motor 12 drives a stepped pulley 14 on a shaft 15, Fig. 4B, which drives a worm 18, Fig. 5, meshing with a worm-wheel 19 on a vertical shaft 20 which, through worms 31 and 33 drives the shafts 21 and 22 of the two rolls 23 and 24. Shaft 21 is mounted in a fixed part of the 'machine frame, but shaft 22 is journalled in a slide 37 which is vertically movable to adjust the pass by means of a screw 42 passing through a nut rotated from a hand wheel 39. In order to accommodate this movement, the worm 33 is axially slidable on a splined upper end of the shaft 20 and is mounted in a housing 36 carried by the slide 37, which may be locked in its adjusted position by bolts 51. For rolling right-hand threads, the roll 24 is made slightly larger (from ten to thirty-thousandths of an inch) in diameter than the roll 23 and vice versa. The shaft 21 is mounted for longitudinal movement and is coupled by a ballbearing collar 76 to a stub shaft 77. A threaded sleeve 78 fitting on the shaft 77 engages a nut 82 formed as a worm-wheel and rotatable through a hand wheel and worm 84. The position of the sleeve 78 which limits the movement of the shafts 77 and 21 to the right, as shown in Fig. 4B, can thus be-accurately adjusted. These shafts can, however, still move towards the left under the action of a piston 86 to either side of which liquid under pressure may be supplied by pipes 88, 89. The blanks to be threaded -are fed down a shoot 92, the lower one being moved forwards between the rolls by a pusher 94 operated by a pressure fluid cylinder 100. A rack 101 on the underside of the pusher engages a pinion 102 on a shaft 103 which also carries another pinion 104 meshing with a rack 105 acted upon by a spring 106 which thus acts to return the pusher 94 when the operating pressure is released from the cylinder 100. The shoot 92 and the pusher mechanism are mounted on a slide 112 which can be vertically adjusted by a screw 113 to bring the pusher to half the height of the gap between the rolls. Completed blanks are discharged on to adjustable trays such as 90. Lubricant is supplied to the work by a nozzle 116. In operation, a starter button 163 is pressed to start the motor 12 driving the rolls 23 and 24 and another button 166 is. pressed to start a motor which operates the pump of the hydraulic system. Oil is supplied from pipe 88 to the inner face of piston 86 to move the shafts 77 and 21 and hence the roll 23 to the extreme right as determined by the sleeve 78. Pressing another button 176 causes oil to be supplied to the cylinder 100 to operate the pusher 94 which moves a blank 25 from the shoot into the roll pass, at first rapidly and then slowly. The building up of pressure in cylinder 100 as resistance to the forward movement of the pusher increases, operates through a solenoid and a valve to open the inner face of piston 86 to discharge so that the roll 23 is free to adjust itself longitudinally as rolling proceeds. Further forward movement of the pusher causes a screw 168 to engage a contact 169 to cause pressure oil to be delivered. to the other side of piston 86, thus giving the roll 23 an axial movement which causes the ejection of the rolled blank on to the tray 90.