| 摘要 |
PURPOSE:To easily bulge even high hard stocks by installing a cylindrical member in a linear inductor metal die shaped in accordance with the outside shape of a formed product, heating the stock by a high frequency electric current, and giving the inside of the member a pressure. CONSTITUTION:Coils 1 and 2 consist of a linear inductor of a high conductive material such as copper formed into a hollow shape and their inside peripheral surface is formed into a shape corresponding to the outside shape of a formed product. A tube stock 5 as a cylindrical member is inserted into the coils 1 and 2. A high frequency electric current is conducted in the coils 1 and 2 to heat the stock 5 and an internal pressure by a liquid, etc. is given to the stock 5 to bulge the stock 5 in accordance with the inside shape of the coils 1 and 2. Therefore, even high hard material such as carbon steel is easily bulged.
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