| 摘要 |
PURPOSE:To prevent holding rollers from abrasion, by holding a plug bar by holding rollers after advancing the plug bar to a prescribed position by using swingable supporting rollers. CONSTITUTION:When the tip of plug 5 of a plug bar 6, being advanced by a rack-bar 10, passes through supporting rollers 12; levers 13 contact with worm- jacks 16 being set to a prescribed dimension of the plug bar 6 previously by actuating cylinders 17 in sequence, and raise the supporting rollers 12 so as to support the plug bar 6. At this time, holding rollers 11 are opened not to hold the bar 6. When the advance of the bar 6 is finished; the rollers 11 close to hold the bar 6, and the lever 13 contacts with the worm-jack 15, previously set to the prescribed dimension of a blank hollow pipe 2, to move the rollers 12 downward by actuating the cylinders 17 simultaneously. On the other hand, a ratch is closed by cylinders 9 to fix the rack-bar 10 and plug 6, then the preparation for piercing is completed. |
