Hollow metal part of stator of rotating electrical machine, rotating electrical machine, and manufacturing process of hollow metal part

A hollow metal part of a stator of a rotating electrical machine that is used as a pipe component for a refrigerant flow path of the rotating electrical machine adapted to cool a stator coil with a refrigerant,

• wherein the rotating electrical machine includes a connection arm and an insulating hose at a stator coil end portion of the stator coil, the connection arm is coupled to the stator coil, the insulating hose being coupled to the stator coil and the connection arm through a first hollow metal part in order to supply the refrigerant to the stator coil and the connection arm;
• and
• wherein the first hollow metal part includes a bend, a first end coupled to one end of the bend, and a second end coupled to the other end of the bend,
• wherein at least a part of the bend is formed of stainless steel,
• wherein the first end and the second end are formed of oxygen-free copper, and
• wherein the first hollow metal part is formed integrally by joining a portion formed of stainless steel at the bent portion and portions of the first end and the second end formed of oxygen free copper by HIP diffusion bonding.