GB828645A - Improvements in friction-driven screw presses - Google Patents

Abstract

828,645. Screw presses. ETABLISSEMENTS GRIMAR. June 26, 1957 [Nov. 9, 1956], No. 20138/57. Class 87(2). The flywheel 1 of a friction-driven screw press, in which the flywheel moves axially with the screw spindle 4 and the cross-head 18, is driven alternately in either direction by two vertical drums 22, 23 which are fixed in the axial direction, and have an axial length in that direction at least equal to the travel of the flywheel. The spindles 26, 27 of the drums are carried by double-armed levers pivoted at 30, 31 and connected at their other ends through rods 34, 35 to a doubleacting piston 36 which is constrained in a neutral position in its cylinder 37 by opposed springs 40, 41. The drums are freely rotatable on their spindles and are belt-driven from motors 49, 51. The screw spindle 4 is guided in its travel by an upward extension 12 which passes through a bore 13 and the spindle has keyed. to it, above the cross-head 18, a brake pulley 16. The cross-head carries a spindle 55, Fig. 5, on which are pivoted two jaws 53, 54 enclosing the brake pulley 16 and normally closed thereon by a spring 62 acting on a piston 58 in a cylinder 56. The operation of two switch buttons 88, 89, or a pedal switch 90, Fig. 6, causes electrically controlled valves to admit pressure fluid to the cylinder 56 and, through a port 43, to the left of the piston 36 in the cylinder 37, whereby the brake is released and the rotating drum 22, is pressed against the flywheel 1. The cross-head 18 is therefore driven downwards on its pressing stroke. At the bottom of the stroke a cam 75, attached to the cross-head, actuates a limit switch 73 which causes a reversal of fluid pressure from the left to the right of the piston 36, the drive of the flywheel being thus transferred to the drum 23, causing the cross-head to rise. At the top of the stroke a limit switch 71 is operated, causing the release of fluid pressure from the cylinders 37, 56 and so resulting in the return of the piston 36 to its neutral position and the re-application of the brake jaws 53, 54, the spindle and flywheel thus becoming immobilized. The positions of the limit switches 71, 73 are adjustable on a bar 68. The force of the blow delivered by the press may be controlled by altering the position of a circuit breaker 79 on a bar 76. If the circuit breaker 79 is raised a cam 82 on the crosshead opens it during the dow-nstroke and results in earlier release of the fluid pressure from the cylinder 37 and therefore earlier release of the drum 22 from contact with the flywheel, thus lessening the force of the blow. The cam and circuit breakers carry pointers which indicate their positions on a scale 81.