Feed nozzle for injection moulding machine - has protrusion into polymer passage to give better flow pattern and less waste when colours are changed

摘要

A nozzle for supplying molten polymer to an injection moulding machine has at its tip (22) a protrusion (25) which projects into the circular cross-section of the polymer channel. The protrusion can have a number of shapes and can extend to various lengths along the polymer channel. A nozzle is held in a housing and is heated by electric heating cuffs fed from an electric cable. Polymer is supplied through a circular duct and then flows through a duct past the protrusion into a paraboloid space. In a typical application the number of flushing shots required for a change of colour was reduced to less than a quarter from the previous value of 25. USE/ADVANTAGE - The method impoves the flow pattern so that colour change-overs incur less waste.