Manufacturing method of piston with a hollow space for compressor

A method of manufacturing a piston, for a compressor, in which a hollow piston is manufactured by welding plural piston parts, comprising:

• assembling plural piston parts into a piston assembly comprising an internal hollow space;
• placing the piston assembly into a reduced pressure area;
• and
• performing electron beam welding on all coupling portions of the piston assembly so that each of the piston parts are integrated into a unit under the reduced pressure, and the hollow space forms a hermetically sealed space which is at a pressure equal to that in the reduced pressure area,
• wherein the step of placing the piston assembly into a reduced pressure area further comprises steps wherein:
• a jig having a housing recess that can accommodate the piston assembly is used;
• the jig is brought and placed by a conveying guide to a position in which the housing recess of the jig communicates with a welding chamber of an electron beam welding device;
• and
• a sealing means is provided to isolate the housing recess, which communicates with the welding chamber, from the outside air.