PURPOSE: To reduce weight and improve shock resistance and abrasion resistance by fitting and fixing a pipe made of fiber-reinforced resin on the inside of a metal pipe whose surface is hardening and strengthening-treated.
CONSTITUTION: A lightweight pipe 1 is constituted of a surface treated metal pipe 2 and a fiber-reinforced resin pipe 3, and the surface hardness of the metal pipe 2 consisting of a low carbon steel pipe is increased to Hv 150-180 in the Vickers hardness difference from the center part of the thickness of the pipe by heat, gas, etc. The resin pipe 3 is hardening-formed to a pipe shape by treating carbon fiber, glass fiber, etc., by the thermosetting type resin such as epoxy resin and phenol resin, or the thermoplastic resin such as nylon resin and polyethylene resin. The resin pipe 3 is fitted on the inner peripheral surface of the metal pipe 2, and attached by an attached sheet made of the thermoplastic resin, thermosetting resin, or epoxy resin contained in the pipe 3 itself, and the pipes 2 and 3 are joined by pressurizing and heating the inside of the resin pipe 3. Accordingly, the static strength of the pipe surface, fatigue strength, shock resistance and abrasion resistance can be improved.
OHORI NAOHIRO
YOSHIZAWA HIROYUKI
TONEN CORP