Hollow coil spring and suspension device for vehicle

A method for manufacturing a hollow coil spring constituted of a hollow wire, the hollow coil spring comprising a terminal sealed portion formed at an end portion of the wire,

• wherein:
• the terminal sealed portion has a rotationally symmetric shape in which an axis passing through a center of the wire is a symmetric axis, in a cross section along the axis, the terminal sealed portion comprises:
• an end wall portion including an end face which is perpendicular to the axis and substantially flat;
• an arc-shaped curved surface formed between the end face and an outer peripheral surface of the wire, wherein the arc-shaped curved surface is a curved surface connecting the end face and the outer peripheral surface of the wire;
• and
• a hermetically closed distal-end-center closure portion located on the axis at a center of the end wall portion, and
• the hollow coil spring includes, in the terminal sealed portion, a recess having a rotationally symmetric shape and located on the axis, on an inner surface of the end wall portion of the terminal sealed portion,
• the method comprising:
• forming a chamfered portion on an inner peripheral side or outer peripheral side of the end portion of the wire, the end portion comprising an opening portion at a distal end before the terminal sealed portion is formed,
• heating the end portion of the wire having the chamfered portion,
• spinning the heated end portion to be gathered toward the axis from the outer peripheral side by a jig,
• forming the end wall portion including the distal-end-center closure portion as the distal end of the end portion joined together on the axis, and
• forming the end face on the end wall portion.