| 摘要 |
A helix of great length wherein the structure is filled with a filler and wherein the structure is produced by a practice in which the helix structure and filler material are caused to rotate about each other upstream of the point of convergence, while the helix retains its orientation, and the speed of advance of the helix and the speed at which the filler material and helix are rotated are so adjusted that the helix is advanced by one winding during each rotation. |
