| 摘要 |
An apparatus for pre-piercing billets includes a generally cylindrical container for receiving and supporting a generally cylindrical billet, a mandrel bar mounted for axial movement along the axis of the cylinder for penetrating the billet, and a bolster for engaging the billet during penetration of the billet by the mandrel bar, wherein the bolster includes a bolster pin which is axially movable along the axis of the container, the bolster pin having an end which contacts the billet during penetration of the billet by the mandrel bar such that the billet deforms about the end of the bolster pin. A movable support is carried by the mandrel bar toward the billet during advancement of the mandrel bar prior to pre-piercing the billet, the movable support being configured to enter the generally cylindrical container to engage a portion of the container so as to provide additional structural rigidity to the mandrel bar to resist deflection of the mandrel bar during penetration of the billet. |
