| 摘要 |
PROBLEM TO BE SOLVED: To form a duct one end of which is square and the other end of which is round and which is easy to be formed with little welding by inserting a square receiving die from one side end surface of a cylinder or truncated cone, pressurizing two facing surfaces from the outer surface of the cylinder or truncated cone and pressing one side end surface into a square. SOLUTION: A truncated cone or cylinder 1 is manufactured by rolling up a plate. A square receiving die 2 having round corners is set in the inside of one side end of the truncated cone or cylinder 1. Two surfaces facing the receiving die 2 are pressurized with a pair of pressure dies 3 from the outer surface of the truncated cone or cylinder 1. After vertical pressurizing, horizontal pressurizing is applied to form a square. Moreover, simultaneous pressurizing may be applied with two pairs of the pressure dies 3 vertically and horizontally. Also, vertical and horizontal pressurizing may be alternately repeated. The truncated cone 1 may be a cylindrical shape. Smooth deformation from the square in one end to the round in the other end is preferable.
|
