Method of producing an annular foam product

A method of producing an annular foam product having a core structure and a tubular skin, said core structure including a connecting portion and a generally U-shaped portion which cooperate with each other to form an annular frame, said tubular skin being formed by joining sheet members to form an annular tube which encloses said annular frame of said core structure, such that a cavity is formed between said tubular skin and said annular frame, said method comprising the steps of:

• placing a plurality of skin members so as to surround respective parts of said U-shaped portion of said annular frame of said core structure, such that a nominal inside of each said skin member is exposed;
• joining together opposite edges of each of said plurality of skin members, so as to form tubular skin members, such that the joined edges of each said skin member are located outside of said tubular skin members;
• joining together the tubular skin members end to end to form a U-shaped skin tube, by (a) turning over one of the adjacent tubular skin members to expose a nominal outside thereof, (b) superposing the other of said adjacent tubular skin members on said one tubular skin member such that nominal outer surfaces of said adjacent tubular skin members face each other, (c) joining one end of said one tubular skin member to a corresponding one end of said other tubular skin member, and (d) turning over said other tubular skin member to expose a nominal outside thereof, said U-shaped skin tube surrounding said U-shaped portion of said annular frame;
• joining each of opposite ends of a skin sheet to a corresponding one of opposite ends of said U-shaped skin tube while end portions of said skin sheet including said opposite ends thereof are turned inside out;
• turning over said end portions of said skin sheet such that a nominal inside thereof is on the side of said connecting portion of said annular frame, and arranging said skin sheet to surround said connecting portion;
• joining together opposite edges of said skin sheet along said connecting portion, thereby forming a connecting skin tube which surrounds said connecting portion of said annular frame, said U-shaped skin tube and said connecting skin tube cooperating with each other to constitute said tubular skin in the form of said annular tube which encloses said annular frame of said core structure to form a cavity;
• and
• injecting a foamable material into said cavity formed between said tubular skin and said annular frame, and filling said cavity with a foam filler formed by the injected foamable material.