| 摘要 |
PURPOSE:To lighten a constituted member by using a round pipe material as a stock and forming the square cross sectional shaped constituted member having a special shaped part in a part. CONSTITUTION:A position 3 for forming the special shaped part in a square cross sectional shaped special shaped tube product is pre-worked so as to form the smaller dismeter than the other position 4 from the round pipe material 2. Successively, the pre-worked round pipe material 2 is bent at the prescribed angle and if necessary, roughly worked to almost the square cross sectional shape by outer pressure, such as pressing, hammering, and this worked material is incorporated into a bulging die to apply the bulging work. The round pipe material 2 integrally formed as a finder by an extruding work, etc., in the axial direction of the outer peripheral surface is used as a stock and can be formed as the same way. By this method, the special shaped tube having the square cross section and the special shaped part at a part is manufactured. |
