MOLD FOR MANUFACTURING COMPOSITE PIPE

摘要

PURPOSE:To prevent the disturbance of the surface of a coated resin or the lowering of the bonding strength to a metal pipe by forming a spiral ridge having a spiral angle almost same to that of the metal pipe to the leading end part of the mold inserted in the metal pipe to extrude a resin. CONSTITUTION:By the presence of the spiral ridge 515 formed to the leading end part of a mold 51 extruding a resin, the resin is spirally guided to be extruded from the leading end of the mold 51. By allowing the spiral angle of the ridge 515 to almost coincide with that of a spiral metal pipe 13, no relative twist in the peripheral direction of the spiral metal pipe 13 is generated between the surface of the spiral metal pipe 13 prepared under rotation and the resin and a composite pipe 14 having sufficient adhesiveness and improved in the surface state of the resin is obtained.