Hollow spring member and manufacturing method therefor

A method of manufacturing a hollow spring member comprising:

• performing shot-peening on an inner surface of a hollow rod which is made of steel and whose ends are open, thereby forming shot peening indentations on the inner surface of the hollow rod;
• blowing a volatile powdered rust inhibitor, which comprises a number of particles, into one opening of the hollow rod, thereby applying the volatile powdered rust inhibitor onto the shot peening indentations on the inner surface of the hollow rod, the volatile powdered rust inhibitor being supplied in an amount sufficient to bring a vaporized component into a balanced state within the hollow rod, the volatile powdered rust inhibitor having reversibility which brings adsorption to and desorption from the inner surface of the hollow rod into balance in accordance with a temperature of the hollow rod;
• removing the volatile powdered rust inhibitor adhered to one end portion of the hollow rod by heating the one end portion of the hollow rod;
• forming a first terminal sealed portion which comprises a first inner surface joined portion, by flattening the heated one end portion along a radial direction of the hollow rod, the first terminal sealed portion including a first terminal gap that decreases in size toward the first inner surface joined portion;
• removing the volatile powdered rust inhibitor adhered to the other end portion of the hollow rod by heating the other end portion of the hollow rod;
• forming a second terminal sealed portion which comprises a second inner surface joined portion, by flattening the heated other end portion along the radial direction of the hollow rod, the second terminal sealed portion including a second terminal gap that decreases in size toward the second inner surface joined portion, thereby forming an enclosed space inside the hollow rod, an amount of the volatile powdered rust inhibitor which is contained in the enclosed space being an amount which brings adsorption to and desorption from an inner surface of the enclosed space into balance;
• bending the hollow rod;
• vaporizing a component of the volatile powdered rust inhibitor within the enclosed space, and creating a rust-inhibiting atmosphere within the enclosed space by the vaporized component of the volatile powdered rust inhibitor reaching a saturation state;
• and
• forming an inner surface rust-inhibiting film on the inner surface of the enclosed space by reversible adsorption of the vaporized and balanced component of the volatile powdered rust inhibitor to the inner surface of the enclosed space, forming a first terminal rust-inhibiting film on an inner surface of the first terminal gap by reversible adsorption of the vaporized component of the volatile powdered rust inhibitor to the inner surface of the first terminal gap and forming a second terminal rust-inhibiting film on an inner surface of the second terminal gap by reversible adsorption of the vaporized component of the volatile powdered rust inhibitor to the inner surface of the second terminal gap.