| 摘要 |
PURPOSE:To manufacture a synthetic steel tube for upgrading bonding strength of a steel tube with concrete by bonding belt-shaped plastic having bonding properties with the inner surface or outer surface of the steel tube in the direction of spiral circumference, and forming projected plastics continuously or partially. CONSTITUTION:A steel tube with projections is a steel tube 1 with plastics 2 of bonding properties provided as projections on its surface, and the projections are bonded with the inner surface or outer surface of the steel tube according to the purposes in the circumferential direction continuously or partially. The shape of projections can be the trapezoid with widened foot, the square projected shape or the projected shape with widened top. The adequate height of the projections is 2-6mm and the adequate width is in the range of approximately 10-30mm, and the interval of projections should be 20-100mm from the viewpoint of resistance to slip of the steel tube and concrete. The procedures of the bonding method of projections consist of subjecting the surface of steel tube to a blasting treatment by means of a blasting device 9 and blasting nozzle 8, heating the steel tube by a heating device 6, extruding plastics of 2 bonding properties out of an extrusion die 4 of a resin extrusion device 5 and bonding the same with the steel tube. |
