Development Of Inductive Heater In Butt-fusion Welding Machine For Pressurized Plastic Pipes

Pressurized plastic pipes have been used extensively in our country,but the welding technique and the welder of it are still backwardcompared with those of foreign countries. There are two main weldingmethods of pressurized plastic pipes: butt-fusion welding andelectrofusion joining. Butt-fusion welding is fit for pipes whose diameteris above 90 mm. This method is economical and reliable.Butt-fusion Welding Machine is a equipment specializing inpressurized plastic pipes. The Welding Research Institute of TianjinUniversity has developed a Butt-fusion Welding Machine. It isautomatically manipulated, but heating-up time of the heater is too long.So we tried new methods and developed an inductive heater based onelectromagnetic induction effect.The inductive heater comprises high-frequency power supply,inductor and hot plate. High-frequency power supply uses IGBT forswitching component. Control circuit uses SG3524 for pulse widthmodulator (PWM). The drive uses EXB841 for driver and has strongnoiseproof feature, high actuating speed and perfect protection.High-frequency power supply contains a temperature control systemwhich can display temperature of the hot plate and make it range in 200℃and 220℃. The inductor is made up with twisted enameled-wire and hassix high-frequency magnetic stripes in its back.It takes only 2 minutes for the temperature of the hot plate to risefrom room temperature to operating temperature. The butt-fusion jointwelded by this heater has higher tensile strength than that of base material.So It induction heating is a feasible method to use.