| 摘要 |
<p>1,184,113. Punching. MINSTER MACHINE CO. 9 March, 1967 [12 May, 1966], No. 11148/67. Heading B3W. [Also in Division F2] A shock-absorber for damping out rebound vibrations at the point of breakthrough of a workpiece in a press (12), Fig. 3, not shown, comprises a variable volume chamber 28 which is filled with hydraulic fluid 30, is formed by a piston and cylinder unit 24, 26, and has at least one metering orifice 40 through which fluid is exhausted, e.g. when a slide (16) actuates a strike plate 22 attached to the piston 24, a metering pin 36, carried by the piston 24, moving into restricting relation with the corresponding orifice 40 as the slide moves downwardly, and the orifice 40 being restricted to the maximum extent, at the point of breakthrough, when the maximum diameter portion 57 of the pin 36 moves into the orifice 40, and means for an inflow of fluid to the chamber 28, e.g. a valve 80, when the slide (16) moves upwardly. Fluid is returned to the expanding chamber 28 from an accumulator (45) through passages (44, 43) controlled by the spring- loaded, one-way valve 80, upward movement of the piston 24 being restricted by a stop ring 90. The metering pins 36, which have threaded engagement with the piston 24 and have seals 52, may have constant-diameter operating portions. The piston 24 does not bottom on the base 76 of the cylinder. In a modification, Fig. 4, not shown, the shock-absorber has a single metering pin (236) axially adjustable by a nut (235) and two one-way re-charging valves (257), the variable volume chamber (228) discharging into a chamber (245) which is separated from a pneumatic spring chamber (253) by a movable wall (247). In a further modification, Fig. 7, not shown, the shock absorber piston (326) is not operated until the piston (320) of a counterbalance air spring (322) has moved downwardly its full stroke, whereupon the piston (320) contacts the piston (326) and the damping action occurs in a manner substantially as described in the previous embodiments. In an alternative arrangement, Fig. 9, not shown, the metering pin (418) can be adjusted from outside of the shock absorber a single unit only of which is necessary to effect damping.</p> |
