GB229977A - Improvements in the art of shearing metal bars while in motion - Google Patents

Abstract

229,977. White, A. E., (Morgan Constru ction Co.). Oct. 28, 1924. Combined fluid - actuated and mechanical gears.-The valve gear of a metal bar shearing machine comprises a main differential piston valve 30, Fig. 3, whose movements are controlled by a pilot valve 40, Fig. 5, mounted in a chest 35 secured to the part 27 of the main valve casing. Main steam is supplied at 28 and may pass to the cylinder 16 as controlled by the main valve either by way of ports 32 or 34, a throttle 70 which may be set by a hand lever 71, being fitted in the port 34 to control the speed of the piston and hence to determine the length of work cut off at each operation of the shears. The pilot valve is first actuated by the work to move the shears for the cutting stroke and is then automatically controlled by linkage from the shears to return the latter to the starting position. The work 5 on moving forward trips a trigger 51 and actuates a pawl engaging a ratchet-wheel on the pilot valve spindle, the pawl riding on a ledge on the valve chest so that whatever the movement of the trigger may be, the pilot valve turns through only 45‹. This movement connects the ports 37, Fig. 5, which open into the right hand end of the main valve casing, with atmospheric exhaust ports 36, so reducing the pressure accumulated in the casing-end by leakage through a bleedport 73 in the valve and allowing the steam pressure to move the valve to the right. Steam is thus admitted through the port 32 to the right hand and exhausted through the port 34 and pipe 29 from the left hand end of the cylinder, the piston thereupon moving inwards and performing the cutting stroke. During this movement, a bye-pass valve 61 actuated at a given adjustable point in the stroke by linkage 65, 68 from the shears cuts off the steam supply and admits steam from the right hand to the left hand end of the cylinder, this cushioning action being also assisted by a bleed-port 74 in the piston and by a recess 76 in the cylinder wall. Meanwhile, a second ratchet wheel on the pilot valve spindle is similarly rotated through 45‹ by linkage 58, 60, 68 whereby the atmospheric exhaust ports 36 are shut, the accumulation of pressure in the right hand end of the main valve casing causing the valve to move to the left. This movement uncovers the port 34 and, owing to the difference in the effective areas of the two sides of the piston 15, the entering steam causes the latter to perform its outstroke to return the shears to the starting position.