Piston and method of manufacture

Abstract

A piston particularly adapted for heavy-duty diesel engine applications is fabricated from separate parts having circumferentially extending joining surfaces that are heated prior to bonding to an elevated temperature sufficient to enable bonding of the joining surfaces, and thereafter the joining surfaces brought into contact with one another and twisted to attain a permanent metallurgical weld at the interface of the joining surfaces. The piston has radially spaced walls which are both welded simultaneously. The weld joints may lie in the same or different planes. Once joined, and while still hot, the parts may be pulled apart slightly to reduce the wall thicknesses at the weld joint.

Description

Background technique [0001] This application is a continuation of application serial number 10 / 701,274, filed November 4,2003. [0002] Various methods are known for welding individual piston parts into a single piston. One of them is friction welding, that is, a piston part is quickly rotated and stamped on another part, and the two parts are welded together by friction to generate sufficient heat. Other methods include resistance welding and induction welding, where after the parts are in contact, a stream of energy is directed at the welded faces of the parts to heat them sufficiently to be welded to each other. [0003] US Patent 5,150,517 is an example of friction welding, while US Patent 6,291,806 is an example of typical induction heating. Among them, induction coils are placed on both sides of the contacting welding surface to conduct energy to heat the interface. This lateral placement of the induction coil enables the portion of the weld surface adjacent to the ed...

AI Technical Summary

Problems solved by technology

Such configurations present challenges for induction welding these parts due to limited access to the area where the weld faces are located and the inability to place the induction coil near the mating weld face in the presence of internal cooling channels

As far as the prior art in the piston art is concerned, there is no suitable induction welding technique for a complex structure such as that demonstrated in the aforementioned '642 patent, and also due to the application of such induction welding techniques to complex pistons with multiple radially spaced weld faces There are practical difficulties in the design, so there are no application examples

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