| 摘要 |
<p>A strap sealer (10) has a dual action piston (24). A seal forming assembly (56,58) is operably connected to the piston (24) by a ram (28). The sealer includes a housing (12) that defines a cylinder (20) and has a penetration (30) therein. The piston (24) is disposed in the cylinder (20) for reciprocating movement. The piston (24) defines first (46) and second (48) pressure regions of the cylinder (20). The sealer includes a compressed air inlet (36), first and second flow paths (42,44) between the inlet (36) and the upper and lower pressure regions (46,48) and a valve assembly (38) for providing flow communication from the inlet (36) to supply air to the first and second pressure regions (46,48). The ram (28) is mounted to the piston (24) for reciprocating movement therewith. The ram (28) traverses through the housing penetration (30). The ram (28) has first (98) and second (90) cross-sectional areas that are different from one another. When the first cross-sectional area (98) resides at the housing penetration (30) a seal is formed between them and when the second cross-sectional area (90) passes through the housing penetration (30) a vent path (78) is provided from the second pressure region outwardly to vent air from the second pressure region.</p> |
