| 摘要 |
PURPOSE:To make forming easy and smooth the combination of outer and inner tubes by making the section of an inner tube smaller than that of an outer tube and making the circumferential length longer by a specified length and applying expanding force after inserting the inner tube into the outer tube. CONSTITUTION:The sectional area of an inner tube 2 is smaller than that of an outer tube 1 because of a recessed part 3. However, the circumferential length of the inner tube is press-formed longer than inner circumferential length of the outer tube by designed clamping allowance. The inner tube 2 is inserted into the outer tube 1, and a correcting die 1 is inserted into the inner tube 2. Mechanical tube expanding force is applied to the recessed part 3 of the inner tube 2 opposite to the inner face 5 of the outer tube 1. The circumference of the inner tube 2 is enlarged by expanding and fastened to the outer tube 1 with greater degree of fitting corresponding to the clamping allowance of the circumferential length. No large-scaled heating device is required and operation is simple. |
