GB1161904A - Impact Ram. - Google Patents

Abstract

1,161,904. Power hammers. J. B. OTTESTAD. 1 Aug., 1966 [2 Aug., 1965; 11 July, 1966], No. 34420/66. Heading B3H. A fluid-actuated impact ram comprises body 12 having a cylinder 13 closed at one end and containing a slidable hollow hammer plunger 20 closed at one end, and an accumulator piston 31 slidable within the plunger and biased to provide a charging chamber 38 within the plunger. Means 61, 56 are provided for breaking a peripheral seal between surfaces 27, 28 on the plunger and cylinder thereby to allow the full pressure in the charging chamber to act on the plunger and effect a working stroke. The plunger carries a hammer head 100. Pressure gas such as nitrogen is supplied to an accumulator chamber 39 from source 54, Fig. 8, through valve 55 and is replenished when necessary to compensate for leakage. For retracting the plunger 20, hydraulic fluid is supplied by pump 57 through valve 58, duct 62 and port 59 into a return chamber 23, and through ports 51 into the charging chamber 38. Thus the plunger 20 is moved to the right and the piston 31 is moved to the left into the charge position, Fig. 5 (not shown). Meanwhile triggering port 56 is open to exhaust through duct 61. To effect the working stroke, valve 58 is moved to interconnect ducts 61, 62, Fig. 9 (not shown), whereby the pressure in the return chamber 23 is admitted into a triggering chamber 30 to break the seals 27, 28. Pressure in the charging chamber 38 thus acts on the right-hand end of the plunger to produce the working stroke, Fig. 7 (not shown). The piston 31 moves to the right until it seats at 46 in the open end of the plunger; this restricts flow of fluid from the return chamber to cushion the end of the working stroke. The energy level of the ram is adjusted by the charging pressure. This pressure may be sufficient to provide a vibratory movement only of the plunger. In another embodiment, Fig. 10 (not shown), the ports 51 are omitted and the charging chamber is pressurized through duct (93) and port (52). Triggering is effected by valve (95). A mechanical triggering device (102), Fig. 12 (not shown), may be used. In another embodiment, Figs. 13-15 (not shown), stepped portions 113, 114 of the piston provides a coasting stroke of the plunger before cushioning takes place. In a further embodiment, Figs. 16-18, the plunger strokes are repeated automatically.