| 摘要 |
PURPOSE:To prevent the seizure occurring in the deterioration arising from the cyclic use of a lubricating oil by coating the high-viscosity lubricating oil having substantially no fluidity to the required section on the pointing end side of the inside surface of a blank pipe prior to drawing of the blank pipe then drawing the pipe by using a plug while supplying continuously the lubricating oil to the inside and outside surfaces of the blank pipe. CONSTITUTION:The high-viscosity lubricating oil 8 is coated to the pointing part 5 on the inside surface of the blank pipe 1 as shown in the figure (p) prior to drawing. The blank pipe 1 is then drawn by a die 3 as shown in the figure (q). Since the oil 8 is of a high viscosity, the outflow of the oil coated on the upper side of the pipe 1 to the lower side and the consequent lack of the oil in the upper side part are obviated and the pipe is drawn satisfactorily while the high resistance to seizure is maintained. The oil is supplied continuously to the inside surface of the pipe, as shown by an arrow (b), through a mandrel 4 from an oil tank as shown in the figure (r) in succession to the end of drawing the pointing part 5 of the pipe 1 and the pipe is drawn while the inside surface thereof is lubricated. The crop 9 at the pipe end is discarded as shown in the figure (s) upon ending of the drawing. The oil 8 is fully removed together with the crop 9 to the outside of the system and therefore the inside surface of the product pipe is surely prevented from staining by the residual oil.
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