Method of producing ring member

A method of producing a ring member comprising:

• a cutting process in which a rectangular sheet material is formed by cutting a strip-shaped material pulled out from a coiled material;
• a joining process in which opposite edges of the sheet material are butted, and a cylindrical member is formed by joining the edges to each other;
• and
• a ring formation process in which a ring member with a ring shape is formed by cutting the cylindrical member in a direction perpendicular to an axis of the cylindrical member,
• wherein the cutting process includes a first cutting process in which the strip-shaped material is cut along a first section line parallel to or perpendicular to a reference section line that is an edge of the strip-shaped material on a side facing a direction in which the strip-shaped material is pulled, and includes a second cutting process in which the strip-shaped material is cut along a second section line perpendicular to the first section line, and
• wherein the cutting process is performed before the joining process.

A method of producing a ring member comprising:

• a cutting process in which a rectangular sheet material is formed by cutting a strip-shaped material pulled out from a coiled material;
• a joining process in which opposite edges of the sheet material are butted, and a cylindrical member is formed by joining the edges to each other;
• and
• a ring formation process in which a ring member with a ring shape is formed by cutting the cylindrical member in a direction perpendicular to an axis of the cylindrical member,
• wherein, in the cutting process,
• i) the strip-shaped material is cut along one of a first section line parallel to a reference section line that is an edge of the strip-shaped material facing a direction in which the strip-shaped material is pulled, or a second section line perpendicular to the reference section line, and then
• ii) the strip-shaped material is cut along the other of the first section line or the second section line, that is perpendicular to the line previously cut,
• wherein in the joining process, the reference section line and the first section line of the sheet material formed in the cutting process are butted so as to match a vertex at which the reference section line and the second section line meet with a vertex at which the first section line and the second section line meet;
• and the reference section line and the first section line are welded to each other from an uncut end portion that is opposite to the second section line, toward the two matched vertices.