| 摘要 |
PURPOSE:To prevent effectively the necking in the shaft part of a stepped shaft- shaped metallic product and to obtain the satisfactory product in the stage of forming the shaft part having a large reduction of area of said product by specifying the shape of a die and the relation between the diameter of the formed shaft part and the diameter of a blank material with respect to the height at the peak part of the die. CONSTITUTION:Working by cross rolling to a large reduction of area, i.e., a small ratio d/d0 between the final diameter (d) in the shaft part of the product and the diameter d0 of the blank material is executed. The die of which the height from the reference die plane at the peak part of the die in contact with the above-described shaft part increases steplessly toward the advancing direction of the die from the start point of the force expanding part B or near said point to the start point of the finishing part C or near the same is used in this stage. The roll-forming is so executed that the diameter (d) of the formed shaft part and the diameter d0 of the blank material corresponding to the height at the peak part of said die satisfy the equation (alpha = the wedge angle of the die, beta = the lead angle of the die). |
