Method for manufacturing welded piston shock absorber

Claim 1

A method for manufacturing hydraulic shock absorber subassemblies including a piston rod and a hollow piston member with internal valving components and a heat sensitive peripheral seal comprising the steps of: preforming the piston rod to have a weld projection on a tapered end to be heat upset in a radially outward direction, cold forming a hollow piston having a base portion and an open ended flange, undercutting a portion of said base portion to form a closed center weld surface thereon, forming flow openings through said base portion around said weld surface at an inclination with respect to the central axis of said piston, securing a heat sensitive seal element on the outer periphery of said piston, locating the weld projection of said rod concentrically with respect to the outer diameter of said seal element and against the weld surface on said weld surface radially inwardly of the flow openings, applying pressure to the concentrically aligned piston rod and piston to cause said weld projection to bear against the weld surface, applying a predetermined pulse of direct current across electrodes connected to the rod closely adjacent the tapered end thereon and an electrode connected to the piston at the closed center weld surface thereon to heat the tapered end and the weld surface of said piston to cause them to integrally weld together while simultaneously upsetting the weld projection and tapered end of the rod to fill the undercut portion without encroachment into the flow openings through the piston, aligning valving components within the interior of said piston to have peripheral support portions thereon located radially outwardly of the interior intersection of the flow openings through the piston and the valve components for unrestricted flow of fluid therethrough, and deforming the open ended flange of the piston radially inwardly into engagement with the peripheral securing portions of the valving components for holding the valving components between the deformed end of the piston and the base portion of the piston radially outwardly of the flow openings therein.

Claim 2

A method for manufacturing hydraulic shock absorber subassemblies including a piston rod and a hollow piston member with internal valving components and a heat sensitive peripheral seal comprising the steps of: preforming the piston rod to have a weld projection on a tapered end to be heat upset in a radially outward direction, cold forming a hollow piston having a base portion and an open ended flange, undercutting a portion of said base portion to form a closed center weld surface thereon, forming flow openings through said base portion around said weld surface at an inclination with respect to the central axis of said piston, securing a heat sensitive seal element on the outer periphery of said piston, locating the weld projection of said rod concentrically with respect to the outer diameter of said seal element and against the weld surface on said weld surface radially inwardly of the flow openings, applying pressure to the concentrically aligned piston rod and piston to cause said weld projection to bear against the weld surface, applying a predetermined pulse of direct current across electrodes connected to the rod closely adjacent the tapered end thereon and an electrode connected to the piston at the closed center weld surface thereon to heat the tapered end and the weld surface of said piston to cause them to integrally weld together while simultaneously upsetting the weld projection and tapered end of the rod to fill the undercut portion without encroachment into the flow openings through the piston, aligning valving components within the interior of said piston to have peripheral support portions thereon located radially outwardly of the interior intersection of the flow openings through the piston and the valve components for unrestricted flow of fluid therethrough, and deforming the open ended flange of the piston radially inwardly into engagement with the peripheral securing portions of the valving components for holding the valving components between the deformed end of the piston and the base portion of the piston radially outwardly of the flow openings therein.