Patent GB-672089-A (GB)
Title: Improvements in or relating to a metal working press
IPC: B30B1/26
Filed: 1950-05-19
Abstract: 672,089. Gearing for starting and stopping machinery. CLEARING MACHINE CORPORATION. May 19, 1950 [June 3, 1949], No. 12597/50. Class 80 (ii). In a metal working press, a spring-disengaged plate clutch 21, Fig. 3, between the crankshaft 16 and a driving flywheel 20 is engaged by air pressure supplied through a pipe 30, while a spring-engaged shoe brake 19 is disengaged by air pressure supplied through a pipe 31, the supply to the pipes 30, 31 being under the control of a sleeve valve 29, Fig. 16, which is opened, so as to cause engagement of the clutch and disengagement of the brake, consequent on the depression of a treadle, and which is closed, whether or not the treadle is released, so as to stop the press after one revolution of the shaft 16. Means are provided whereby the valve may be held open so as to permit continuous operation of the press so long as the treadle is kept depressed. The valve 29 is moved by a forked arm 71 pivoted at 74 to the frame and actuated by a link 75 carrying a pin 83 which is held by a spring 82 against a cam projection 86 on a collar 87 secured to a vertically-movable rod 88. The latter is pressed upwards by a spring 91 so that the pin 83 normally rides down the lower inclined surface 84 of the cam 86 to hold the valve 29 in its lower closed position. When the rod 88 is moved down, the pin 83 will ride along the upper inclined surface 85 of the cam 86 and lift the fork 71, thereby moving the valve 29 to its upper open position. The lower end of rod 88 is connected by a link 94 to an arm of a shaft 102, Fig. 9, to which is secured a pawl 112 which is normally held upwardly, as shown, by a spring- loaded plunger 113. The pawl cooperates with shoulders 133, 134 on a link' 117 suspended from an arm 119 pivoted on a shaft 120, the link 117 being urged against the pawl by a spring-loaded plunger 136. A plate 142 pivoted at 143 to the frame is also urged against the pawl by a spring-loaded plunger 147 and has a shoulder 145 co-operating with the pawl. A plate 121, pivoted on the shaft 120 and connected by a rod 131 to the treadle, has two holes, one or other of which receives a spring-pressed pin 125 carried by the arm 119 so as to couple the plate and arm together in one or other of two relative positions. As shown, the pin 125 engages the upper hole in the plate. Thus, on depression of the treadle, plate 121 and arm 119 move clockwise, link 117 moves downwardly and, by means of the shoulder 133, moves the pawl 112 clockwise, thereby moving the rod 88 down, causing the valve 29 to open and the press to operate. As the pawl 112 reaches its lower position, it is engaged by the shoulder 145 of plate 142 and is thereby held in this position whether or not the treadle is released. At the end of one revolution, a cam 164 on the shaft 16 moves a spring-pressed bellcrank lever 153, 154 pivoted on the shaft 120, so that a. pin 161 on the arm 154 tilts the link 117 to the right. A pin 146 protrudes from the plate 142 in the path of movement of the link 117, so that, in the continued movement of the link 117, the plate 142 is also tilted and the pawl 112 is released. The spring plunger 113 now operates to lift the pawl, whereby the rod 88 is raised to close the valve 29 and stop the press. If continuous operation of the press is required, the arm 119 is moved so that its pin 125 engages the lower hole 128 in the plate 121. This lowers the link 117 so that, when the treadle is depressed, the shoulder 134 engages the pawl 112, and a recess 135 in the link 117 is in the path of movement of the pin 161, so that the latter cannot operate to tilt the link 117 and the press continues to operate so long as the treadle is kept depressed.