GB810295A - Improvements in and relating to an automatically-indexing and self-locking rotary moulding or like work-table - Google Patents

Abstract

810,295. Rotary-table moulding-machines. COAL INDUSTRY (PATENTS) Ltd. June 8, 1956 [June 9, 1955], No. 16654/55. Class 87(2). An automatically indexing and self-locking rotary work-table is controlled by mechanism whereby, as the work-table approaches each index position, it is decelerated by the engagement of a deceleration plunger with one of a plurality of deceleration cams on the work-table, before locking mechanism is brought into operation, depression of the deceleration plunger operating a speed control valve to decelerate a hydraulic driving motor. When, on withdrawal from a mould cavity 12A in the work-table 10, the press plunger 13 reaches the top of its stroke a projection 100T thereon trips a pivoted rod 100 and operates on air valve 101. This causes the piston of an air cylinder 37 to rise and, through linkage shown in Fig. 2, to retract a detent 38 from a notch 39 in the periphery of the table 10, the linkage including an override latch 40 which transmits the movement by its engagement with a pin 42 on the detent. Outward movement of the detent 38, through a lever 38A, raises a plunger 36A and operates an oil valve 36 to supply oil to a hydraulic motor 27 and so causes rotation of the table. Towards the end of this step in the intermittent travel of the table to its next working position, the gentle slope of a deceleration cam 15 depresses a deceleration plunger 17 which is associated with a speed control hydraulic valve 35 of the type in which tqpered lands coact with suitable porting. Operation of this valve, with a valve 104 to ensure uniformity with varying load, decelerates the hydraulic motor 27 and brings the table gradually to rest. As shown, the cams 15 are also acceleration cams, the steep slope on the other side of the cam causing an acceleration in the first part of the rotary movement of the table before the decelerating action. At the end of the deceleration an index cam 16 moves a trigger plunger 18 outwards and lifts the override latch 40 off the pin 42, freeing the detent 38 to move inwards under the action of a return spring on the plunger 36A. When the next notch comes opposite, the detent springs into it and the plunger 36A descends and causes the hydraulic motor 27 to stop. The bottom of the plunger also operates a pilot valve 105 which in turn causes an air jack 106 to actuate i) the main press valve 108, causing the press plunger 13 to descend into the next mould cavity in the table ; ii) a valve 109 which supplies oil to a hydraulic cylinder 33, so raising a plunger 32 to eject a moulded article out of another mould. The plunger 32 is connected to an ejection plunger 14 by a spring claw release whereby it can be retracted into the cylinder 33 while the upper surface 14A of the ejection plunger 14 remains to act as the floor of the mould cavity. A seal 14D prevents the passage of foreign matter. When the press plunger 13 reaches the bottom of its stroke a projection 100B causes the valve 101 to shut off air from i) the cylinder 37, at which spring pressure causes the plunger 37A to move the override latch 40 back into engagement with the pin 42 on the detent 38 ; ii) the air jack 106, causing spring pressure to reverse the valves 108, 109 whereby the press plunger 13 rises out of the mould and the plunger 32 retracts. The cycle recommences when the projection 100T again meets the rod 100. The table rotates with small clearance above a base plate, on a spring-supported bearing which allows it to abut the ball plate under the line of the plunger 13 when it is pressed into a mould. Specification 807,433 and 809,672 are referred to.