| 摘要 |
PROBLEM TO BE SOLVED: To reduce impact when a fully-elongated piston rod starts for the first time. SOLUTION: This gas spring has a main gas chamber, a second gas chamber, and a seal surface and partitions an air-tight seal between different stroke portions of a piston rod to form two independent gas chambers, which exert forces to the piston rod in the opposite directions to each other so that the net force applied to the piston rod is deceased. When the piston rod lies near its full elongation position, the seal surface provides an airtight seal, and the net force applied to the piston rod minimizes in the direction in which the piston rod moves to its fully elongated position. Accordingly, until the movement has been made so that the mutually acting surfaces complte the air-tight seal, a very small force is required to move the piston rod first from its full elongated position. Therefore, when the fully elongated piston rod makes the first motions, impact or impact force applied to the ram of a press machine is reduced.
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