R.w. Lyall Company, Inc.

Milfuse Systems, Inc.

Lucian H Lyall

Karol Zbigniew Renau

An apparatus and method for attaining fusion temperature at substantially the same time throughout an interface between thermoplastic articles by the controlled application of heat. The method includes providing a sensed temperature signal corresponding with the temperature at the interface, generating a desired temperature signal (such as an analog ramp signal which increases linearly with time) corresponding with a predetermined heat application rate which causes the temperature at substantially all portions of the interface to rise substantially uniformly, providing a heat control signal corresponding with any difference between said signals, and applying heat to the interface at a rate determined by the heat control signal to achieve fusion temperature throughout the interface at the same time. The apparatus includes a heater coil to apply heat to the interface, a sensor to provide the sensed temperature signal, a generator to provide the desired temperature signal, and a differential amplifier to provide the heat control signal. Fault detection circuits stop the process if a heater fault, a temperature sensor fault, or a power supply fault is detected. Testing circuits are included to test the apparatus for proper operation before commencing fusion.

Method and apparatus for fusing thermoplastic materials

A polyethylene pipeline including a plurality of prefabricated pipes of predetermined diameter fused on one end to respective bell fittings to form prefabricated bell and spigot pipe assemblies. The bell connector includes an enlarged in diameter bell connector formed with a socket having an internal diameter for telescopical receipt of the second end of the adjoining pipe length and includes an increased in diameter interior gland for receipt of a helical heating coil. The heating coil is constructed of an electrical resistant wire coated with an electrical insulative coating which is, in turn, coated with a medium density polyethylene coating. The terminal ends of the wire is coupled with electrical connectors protruding to the outside of the bell connector.

Plastic pipeline having rapidly fusible joints and method of making same

A method and apparatus for thermal fusion of thermoplastic pipes. Heat is applied to a joint interface between thermoplastic pipes and a thermoplastic coupling at a slow rate to raise the temperature of the interface to a predetermined preheat temperature, and then at a rapid rate to quickly raise the temperature to the fusion point, resulting in proper localized fusion heating at the joint interface.

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Woodland Hills, CA, United States of America

Lucian H Lyall