PURPOSE: To form a collar, especially an angular collar, by installing a convexed section at the end of opening of the 2nd pipe holding hole of the 2nd equipment which is to be fitted to the concaved section at the end of opening of the 1st equipment, and by deepening the convexed section corresponding to the concaved section.

CONSTITUTION: The 2nd equipment 2 is retreated as shown by the dotted line at the right side, the 1st component 3 is removed, and pipe 8 is fitted and held between the 1st and 2nd holding holes 5 and 7. Then the 2nd equipment 2 is pushed along the direction of arrow and a bulge is given to pipe 8, but, since concaved section 6 is deeper than that of conventional one, the bulge does not come out to concaved section 6 side. When the 1st equipment 1 and 2nd equipment 2 are pushed against to each other, the bulge is completely compressed by convexed section 10, and collar 9 is formed between concaved section 6 and convexed section 10 in accordance with the shape of concaved section 6. When concaved section 6 has an angular shape, collar 9 having the angular shape corresponding to the shape of concaved section is formed.