| 摘要 |
PURPOSE:To reduce the manhour for cold drawing using a drawing handle, to make to drawing highly efficient, and to facilitate crop treatment by using a bottomed tube manufacture by an extension-piercing method as a tube stock and forming a pointing part by piercing a through hole at the bottom center of the bottomed tube. CONSTITUTION:In the extrusion-piercing method, the top end of a mandrel 13 is abutted on a bottom of a tube end to engage the top end to the bottom at the time of punching the tube through a die 14 and a bottomed tube 1 is manufactured by that punching. Using the bottomed tube 1 as a tube stock, a through hole 5 is pierced at the center of the bottom part 1a to form a pointing part 2. Then, a drawing handle head 30 is inserted into the inside of the tube 1 through the hole 5a in the bottom part 1a to set a drawing handle 3. The stock 1 is drawn by catching the handle 3 in the pointing part 2 and pulling and passing the tube 1 through the die 4. After drawing, the produced tube is cut at the pointing part 2 to obtain a product. The material yield is improved by the amount described later because a pointing work such as welding is eliminated and cutting and discarding in a stock stage are not performed.
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