| 摘要 |
Pressurized fluid, pressurized in excess of the yield strength of a billet or rod, is communicated to the exterior of a piercing punch during piercing of the billet or rod to produce tubing, the pressurized fluid is provided to the exterior of the piercing punch during piercing to provide forced lubrication between the piercing punch and the billet or rod to reduce friction therebetween; such communication of pressurized fluid is also for causing self-centering of the piercing punch with respect to the billet or rod during piercing to produce tubing of uniform wall thickness.
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