| 摘要 |
PURPOSE:To easily and completely fill a synthetic resin rust-proofing agent into the internal voids of a multi-twist PC strand. CONSTITUTION:A PC strand is made by twining plural side wires 3 around a core wire 2. As part or the whole of these side wires 3, a modified cross-section PC steel material with an uneven design formed monolithically on its outer peripheral surface is used, and the PC strand, under heating, is threaded into a synthetic resin extruder where a molten thermoplastic synthetic resin material is pressed into from between the respective side wires to the outer periphery of the core wire while pressurizing the molten resin with the pressure head of the extruder, and the molten resin, together with the PC strand, is extruded through the molding die at the tip of the pressure head, thus obtaining a rustproof-coated PC strand 1 with rustproof-coating layer 5 consisting of the thermoplastic synthetic resin adhered firmly to the whole periphery of both the core wire 2 and the respective side wires 3. Owing to the use of a modified cross-section steel material as the side wires, the voids between the side wires communicating with the internal void developed between the outer periphery of the core wire and the side wires are large and also nearly uniformly formed. Therefore, molten resin flows into the PC strand smoothly and uniformly. |
