Piston for vehicle engine and method for manufacturing the same

Abstract

There is provided a method for manufacturing a piston for a vehicle engine, including: a piston assembling step of forming a piston assembly by assembling a first piston part, a bonding member and a second piston part, wherein the first piston part has two or more bonding surfaces separated from each other and extended in a circumferential direction, and the second piston part has two or more bonding surfaces separated from each other and extended in the circumferential direction; a piston diffusion brazing step of diffusion brazing the first piston part, the bonding member and the second piston part under an open atmosphere by heating the formed piston assembly; and a piston cooling step of cooling a piston unit formed by diffusion brazing the first piston part, the bonding member and the second piston part. The piston diffusion brazing step is performed in a piston manufacturing device which includes a partially opened heating zone, a heater for providing heat into the heating zone, and a moving unit moved in one direction in the heating zone. In the piston diffusion brazing step, the piston assembly is heated while being moved at a predetermined speed through the heating zone in one direction by the moving unit.

What is claimed is: 
     
         1 . A piston for a vehicle engine, comprising a piston unit made of steel and having a piston body and a cooling gallery formed in the piston body,
 wherein the piston body has a bonding interface formed in parallel to the top surface of the piston body and passing through the cooling gallery, and   the concentration of a metal different from the material of the piston body decreases from the center of the bonding interface toward the outside of the bonding surface.   
     
     
         2 . The piston of  claim 1 , wherein a diffusion layer containing the different metal is formed on the inner surface of the cooling gallery, and
 the different metal comprises a nickel-based alloy.