| 摘要 |
PURPOSE:To obtain a chain wheel with good yield of a material, by pressing a blocked annular body obtained by bending and welding an annular body, from the axial core direction, forming a flat annular body, and after that, punching a saw tooth on its outside circumferential part. CONSTITUTION:As a material of an annular chain wheel for a crank gear of an automobile, etc., an annular body 1 of a solid or hollow round rod or square rod, etc. consisting of steel or an Al alloy, etc. is used. As for the annular body 1, a material having prescribed length and diameter is selected so that it has dimensions and weight enough for manufacturing a blank mentioned hereinbelow. The annular body 1 is bent and formed in the shape of a ring of an almost true circle, and its both ends are butt-welded, of which a blocked annular body is constituted. It is brought to heat treatment A in order to remove bending residual stress and thermal stress, and after that, a flat annular body 2 is formed by hot or cold pressing from the axial core direction. It is brought to heat treatment B, its residual stress is removed, and in case of an Al alloy, burning is also performed. This blank is punched to an annular chain wheel 3, and a finished product is obtained after finish-working C such as straightening or chamfering, and surface treatment, etc. |
