| 摘要 |
<p>PURPOSE:To improve the corrosion resistance of a product and to reduce the manufacturing cost by executing a plastic coating on one face of a steel strip, executing lock seaming at both end parts as well and executing the plastic coating of the outer face after forming a pipe by a spiral strip steel. CONSTITUTION:A plastic film extruding machine 20, lock seaming roll 22 and pipe forming mandrel 24 are arranged for the steel strip 14 rewound from a coil 16. A plastic film 20a is coated on one face of the steel strip 14 by the extruding machine 20, the both edge parts 14a, 14b of the steel strip 14 are worked by the lock seaming roll 22 and a continuous pipe 12 is formed as a spiral pipe by the mandrel 24. An inner face plastic costing pipe is formed by calking the pipe 12 and an outer face plasting coating is executed by an extruding machine 28. Due to a plastic layer being strongly formed on the inner and outer faces the corrosion resistance of a product is improved. Also, the manufacturing cost is reduced with the simplification of equipment.</p> |
