| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a spiral-tube producing material that has higher flexibility facilitating tube arrangement including inflections and has higher internal-surface smoothness. SOLUTION: A spiral-tube producing material 1 has an engaging piece 2 and an engaging groove 3 in the respective side edges of its cross section, which are connected by a main body part 4 integrally connected with curving elements 41 curved like bellows. The portions 42 of these curving elements 41 for defining the interior surface of a spiral tube are made roughly flush with one another and made adjacent one to the next.</p> |
