摘要 |
A method and apparatus for butt welding two surfaces of different polyethylenes by heating the two surfaces up to different temperatures at which the viscosities of the two different polyethylenes of the two surfaces are equal. The heating device for heating the polyethylene surfaces comprises two separate plates which can be heated up to different temperatures. The device is also provided with pressure regulating means for controlling the pressure at which the two surfaces are pressed onto each other. |