Welded idler and manufacturing method thereof

A manufacturing method of a welded idler, comprising following steps of:

• (1) separately manufacturing two parts, wherein a first cylindrical hot-rolled steel plate was punched, stretched, with a first mold to obtain a flange-like blank, which is cylindrically shaped and has an annular boss on its inner wall;
• a second hot-rolled steel plate is stretched and punched to form a disc-shaped blank with a first groove;
• (2) friction welding a bottom of the flange-like blank and a connecting edge of the grooves of a disc surface of the disc-shaped blank together, to form a prefabricated flange blank, wherein a bearing hole is formed;
• (3) spinning the prefabricated flange blank to form a semi-finished spin product, wherein its circumference surface is divided into two halves to form a second groove extending perpendicularly;
• (4) processing an inner circle surface and a top end surface of the bearing hole, to form a bearing seat with a cover formed on a first side of the bearing seat and a flat ring formed on the other side thereof;
• (5) processing a bottom end surface of the bearing hole;
• (6) performing surface treatment expect to the bearing hole and a surface of the flat ring;
• (7) pressing a bearing into the bearing seat by way of interference fitting;
• (8) pushing a edge of a bottom of the bearing hole to form a bearing cover;
• (9) painting the bearing cover.