GB1452067A - Drop-hammers - Google Patents

Abstract

1452067 Drop hammers HUNT BROS (OLDBURY) Ltd 15 Feb 1974 [16 Nov 1972] 52918/72 Heading B3H [Also in Division F1] A control system for a drop hammer of the kind comprising a tub 2, Fig. 1, slidable between guides 1, lifting gear 5, 7 for raising the tub, and means 6 for releasing the tub has at least one fluidic sensor 20A which produces a signal when the tub is in a predetermined position above its lowest position to release the tub. As described, three sensors 20A, 20B, 20C are provided, the position of each being adjustable so that the tub may be released at any one of three different heights. Operation of one or both of pedals 30, 31 determines which of the three sensors operates the tub release mechanism. A further sensor 20D activates the rollers 7 to raise the tub. Hammering continues as long as one of pedals 30, 31 is depressed and ceases with the tub in a raised position when both pedals are up. If the tub rises above the sensor 20C, a valve 77 is mechanically operated to switch off the drive and apply the clamps 6. To lower the tub after this has happened, a key-operated valve 81, Fig. 2, must be operated and then manually operated valves 89, 91. This causes the clamps to be disengaged and the tub to be lowered against the resistance of the un-driven rollers 7. Fig. 3 (not shown), illustrates the fluidic circuit which is actuated by the sensors. Each sensor produces a cone-shaped jet of air which is disturbed by the tub to produce a back-pressure in the control duct. The system fails safe if the air pressure falls below a predetermined amount or if the electricity supply fails. If either of the lines to pedals 30, 31 is damaged the tub will rise to position 20A and stop. Additional sensors may be added and the hammer may be programme controlled.