Piston rod assembly including preloaded piston head and composite rod

摘要

Piston rod assembly includes a composite piston rod having an entrapment ridge along the length thereof, and a non-integral metallic piston head having two separate piston head sections which are welded together in preloaded engagement against opposite sides of the entrapment ridge. The entrapment ridge has oppositely facing external tapered ramp surfaces which are engaged by correspondingly tapered internal ramp surfaces on the respective piston head sections. When the piston head sections are initially brought into engagement with opposite sides of the entrapment ridge, there is a slight gap between the inner faces on the piston head sections which determines the amount of preload force that must be applied to the piston head sections to eliminate the gap and bring the inner faces into substantial mating engagement with each other for welding.