| 摘要 |
PURPOSE:To manufacture a thermoplastic resin coil tube with superior spring properties by arranging winding pitch substantially as one without applying any external force, and making initial unit stress larger than stationary unit stress. CONSTITUTION:A tube of around 4-12 mm diameter and of around 0.5-2.0 mm tube wall thickness is used normally, and without any external force, the winding pitch of the tube is one (1) substantially. Said winding pitch one (1) means a state that each winding constituting a coil contacts each other and making no space, or in other words, a coil is in the shortest state. The coil tube has considerably much initial stress, larger than stationary unit stress. The same should preferably have potential stress in winding one (1) without any external force, in other words, the inclination of the curve to the displace ment of initial load is large infinitely. In a word, initial unit stress is large infinitely. The coil tube, therefore, after stretched and expanded by external force, shows an extremely superior shrink restoring force when the external force is taken out.
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