| 摘要 |
PURPOSE:To prevent excessive bending stress from developing on a lance pipe and at the same time ease the mounting accuracy by a structure wherein rollers provided on an auxiliary supporting device are made so as to be able to follow up the spiral loci made by a lance pipe. CONSTITUTION:Rollers 507 and 525 are supported rotatably. The inclination angles of shafts 601 and 600 are selected so that the straight lines obtained by projecting the shafts 601 and 600 on a plane parallel to a flat plate 599 in the direction of the arrow A are nearly at right angles to the spiral figure produced by a lance pipe 7. Concretely, 603 and 604 are figures obtained by projecting the shafts 601 and 600 on a plane parallel to the flat plate 599 and straight lines (l) and (m) are spiral loci made by the lance pipe 7 and straight lines (n) and (o) are parallel to the figures 603 and 604 and yet the straight lines (l) and (m) are rendered to intersect the straight lines (n) and (o) nearly at right angles. The outer surfaces of the rollers 507 and 525, which are rotatably mounted about the shafts 601, 600, are made smooth according to a spindle-shaped curve so as to be able to rotatingly follow-up smoothly to the spiral locus produced by a certain fixed point on the lance pipe 7.
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