INJECTION NOZZLE OF INJECTION MOLDING MACHINE

PURPOSE:To enable the titled injection nozzle to perform temperature control of a nozzle tip constituting a resin passage wall at favorable accuracy, by a method wherein the external circumference of the nozzle tip constituted of a magnetic metallic material is constituted of a nonmagnetic metallic material and an electro-magnetic induction coil is wound round and external circumferential body of the nozzle tip. CONSTITUTION:A nozzle tip 3 of the part of a nozzle is constituted of a magnetic metallic material 4 such as die steel or nickel chrome steel or high speed steel and an external circumferential body 10 of the nozzle tip 3 is constituted of a nonmagnetic metallic material such as austentie-based nonmagnetic hot tool steel or highly manganese nonmagnetic steel. The tip of the nozzle forms the nozzle tip 3 and a sprue bushing 9 of a mold 9 into states capable of making facial contact and an electro-magnetic induction coil 4 is arranged by winding the same round the external circumferential body 10 of the nozzle tip 3. With this construction, as a temperature rising speed can be increased by raising calorific value per unit hour of the nozzle tip 3 due to magnetic induction heating and a contacting area between the nozzle tip 3 and mold 8 is large, a rate in temperature fall can be increased by making effective use of a temperature difference between them.