Industrial Technology Research Institute

Wen-Hwa Lu

Chin-Fu Chen

Shan-Chang Chueh

An apparatus and method for manufacturing seamless tubes from hollow billets that will not contain metal oxide, which may be introduced into the extruded metal tube from an oxide layer formed on the inner surface of the hollow billets, so as to improve the quality of the extruded product and extend the service life of the extrusion piercer rod. A de-oxide latch, which has a substantially circular disk shape and is dimensioned such that it is slightly larger than the inner diameter of the hollow billet, is placed in front of the piercer rod so as to remove the metal oxide layer formed on the inner surface of the hollow billet through an upsetting shearing force ahead of the normal stress generated by the forward movement of the extrusion stem. The extrusion apparatus also utilizes a screw and pierce doughnut combination to securely affix the piercer rod to the stem and to effectuate the extrusion of the hollow billet through an extrusion die to form seamless tubes. This arrangement allows an easy interchange between a piercer rod, which is used for extruding hollow billets, and a ram, which is used for extruding a solid billet, so as to improve the versatility of the extrusion apparatus and reduce the manufacturing cost.

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Shoei, Taiwan

Wen-Hwa Lu