| 摘要 |
<p>A flexible intermediate layer in a laminated tube is less hard than the inner synthetic tube around which the other layers are bonded. The tube consists of three layers at least and is intended as a drain in civil engineering work. The intermediate layer is of thermoplastic material to which an adhesion accelerator has been added and it is applied to the inner tube by co-extrusion. An outer tube enveloping the intermediate layer at some little distance from it, is formed by rolling a strip of metal so that the edges butt together and a longitudinal welded seam is formed. After welding the tube is drawn through dies so that its dia. is reduced continuously, and the heat generated during shrinkage acting on the intermediate layer, bonds it to the outer tube. Used to produce a bonded pipe for drainage purposes, fully capable of standing up to the corrosive fluids which are commonly present. There is a close and inseparable bond between the intermediate layer and the inner tube and esp. between the intermediate layer and the metal tube.</p> |
