| 摘要 |
PURPOSE:To enable the production of the small bore thin tube of high accuracy simply and surely by drawing a mandrel with momentary heating of a pipe by an induction heating after making a cup-shaped blank pipe with the drawing work of an Al plate and working it to a small bore thin pipe by a fixed metal die with fitting a mandrel thereto. CONSTITUTION:A cup shaped blank pipe E is made with the drawing work of Al plate D by a die 11 and punch 12. This blank pipe E is pressed in a fixed metal die 14 with fitting to a mandrel 13, the thickness is thinned uniformly with the ironing work of the peripheral wall of the blank pipe E from the outer peripheral face and it is worked to the thin pipe F having the prescribed small bore and length. The high frequency heating coil 15 provided on the periphery of the formed position of the pipe F is electrified and the mandrel 13 is easily drawn with the momentary heating expansion of the pipe F. Even the thin pipe of less than 50mm diameter and more than 300mm length of the pipe F can be produced with excellent dimensional accuracy.
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