Apparatus for making a pneumatic counterbalance

An apparatus to make a pneumatic counter-balance spring link or the like from a pre-assembly of a closed end cylinder with the other end open and a second pre-assembled piston assembly which includes a piston shaft with a free end, a piston fixed on the shaft, and an abutment bushing and an annular seal means on the shaft between the free end and said piston with the seal means between the bushing and the piston comprising:

• a crimping die set with upper and lower hollow telescoping die assemblies adapted to be secured in a press;
• one die assembly having means to releasably secure the piston assembly by the free end of the shaft and the other die assembly having means to hold the cylinder assembly;
• means including said press and said die assemblies to move both die assemblies and the counterbalance unit pre-assemblies toward each other with the piston assembly coaxially aligned with the cylinder assembly and moving toward entry into the open end of the cylinder assembly, said die assemblies having means to seal said die assemblies upon initial engagement and during subsequent movement toward each other to provide a sealed cavity within said engaged die assemblies which will contain the counterbalance link pre-assemblies;
• means to introduce gas under at least several atmospheres of pressure into said sealed cavity prior to further closure movement of the die assembly, which results in insertion of the seal means of the piston pre-assembly into said cylinder;
• means in said die assemblies adapted to cause inward crimping of the cylinder open end by further movement of the die asemblies after said die assemblies have moved together to a position where the bushing of the piston pre-assembly has been moved into the cylinder by movement of the die assemblies;
• means enabling separation of said die assemblies;
• and means operable after crimping to vent pressure from said sealed cavity before reverse movement of said die assemblies opens the sealed cavity.

An apparatus to make a pneumatic counterbalance spring link or the like from a pre-assembly of a closed end cylinder with the other end open and a second pre-assembled piston assembly which includes a piston shaft with a free end a piston fixed on the shaft, and an abutment bushing and an annular seal means on the shaft between the free end and said piston with the seal means between the bushing and the piston comprising:

• a crimping die set with upper and lower hollow telescoping die assemblies adapted to be secured in a press;
• one die assembly having means to releasably secure the piston assembly by the free end of the shaft and the other die assembly having means to hold the cylinder assembly;
• means including said press and said die assemblies to move both die assemblies into an initial engagement to provide a sealed cavity within and between said die assemblies which will contain the counterbalance link pre-assemblies;
• means to introduce gas under at least several atmospheres of pressure into said sealed cavity before the seal means of the piston pre-assembly is forced into the end of the cylinder pre-assembly and prior to the further closure movement of the die assembly, which results in insertion of the seal means of the piston pre-assembly into said cylinder;
• means in said die assemblies adapted to cause inward crimping of the cylinder open end by further movement of the die assemblies after said die assemblies have moved together to a position where the bushing of the piston pre-assembly has been moved into the cylinder;
• means enabling separation of said die assemblies;
• and means operable after crimping to vent pressure from said sealed cavity and before reverse movement of said die assemblies opens the sealed cavity.