| 摘要 |
PURPOSE:To obtain a rim for automobile, etc. free from local thinning and excellent in durability by tracking a material of required width from a coil material obliquely to the direction of rolling, forming it to a cylinder and preforming plural roll formings. CONSTITUTION:A rim material 1alpha of 1beta is taken at an interval of required width (b) from a wide coil material of Lo obliquely to the direction of rolling at a required angle of inclination of alpha or beta. The rim material is rolled up and the end faces are butt welded, and trim-finished to a cylindrical form. Then, it is formed to drum shape in a flaring step, and expanding of outer diameter of rim flange, reducing of inner diameter of rim drop center, etc. are made by roll forming of plural steps, and roll forming is made until the rim section becomes a required shape. Then, the outer diameter is formed to required size in the sizing step. |
