| 摘要 |
PURPOSE:To obtain a J-shaped steel which is equal in wall thickness particularly in the round part and end part by introducing a flat steel plate formed to have a prescribed thickness into a caliber system wherein the crossing parts of right and left flanges have a round shape, and approximating the round shape successively to the product shape then cutting the steel plate to a desired length. CONSTITUTION:A steel material is rolled by a flat steel rolling system up to the midway of hot rolling to manufacture a steel material having the flat steel-like section which is 1.5-2.5 times thicker than a desired product. Such rolled steel material is passed, for example, four times, through the rolls of the succeeding caliber system wherein the right and left crossing parts of the flanges are rounded. The rounded shape is thus approximated successively to the product shape and further the forward ends of the right and left flanges are molded smoothly to obtain the J-shaped steel completed of the rolling. Such J-shaped steel is cut in a cold state, whereby a desired ribbed material is produced. The round part of the J-shaped steel can be made as thick as the flange part or thicker than the same; therefore, the J-shaped steel having higher strength than the cold molded steel of the same size is obtained. |
