Multitip hot runner system

A multitip hot runner apparatus for transporting molten plastic from an injection machine to a plurality of mold cavities while controlling the temperature of the molten plastic, said apparatus comprising:

• a distribution body of given length and having a central longitudinal axis extending therethrough, said body having top and bottom surfaces, a distribution well formed in said top surface for receiving said molten plastic, a plurality of unrestricted and identically configured through flow channels formed between said distribution well and said bottom surface of said distribution body to transport said molten plastic from said well along said flow channels and toward said bottom surface, each of said flow channels having lower sections for releasably receiving tips for transporting said molten plastic beyond said bottom surface to gates of respective mold cavities, a plurality of heating cartridge holes equal in number to the number of said flow channels and equally spaced within said distribution body with respect to said flow channels so that each flow channel is surrounded in said distribution body by an identical thermal mass to assure uniform heating of said flow channels when heating cartridges are present in said distribution body and energized, said heating cartridge holes being non-through holes extending from said top surface of said distribution body to a predetermined length short of said distribution body given length, and a single non-through thermocouple hole, also extending from said top surface of said distribution body to a predetermined length short of said distribution body given length and near said bottom surface thereof, said thermocouple hole being closely adjacent one of said plurality of said flow channels;
• a plurality of heating cartridges one each of which is disposed within said heating cartridge holes;
• a thermocouple disposed in said thermocouple hole for monitoring the temperature near said bottom surface of said distribution body and supplying temperature feedback information for controlling the temperature of all of said flow channels;
• a plurality of said tips for transporting said molten plastic, each of said tips being releasably connected in a respective one of said lower sections of said flow channels and forming therewith an air space to prevent heat loss, said tips being fabricated of a material with high heat conducting properties relative to those of said distribution body to conduct heat from said distribution body outside of said bottom surface thereof to prevent plastic freeze at cavity gates, and
• an interface body attached to said distribution body for receiving molten plastic and transporting it to said distribution chamber of said distribution body, said interface body being adapted to also retain said heating cartridges and said thermocouple within said distribution body and to be heated by said heating cartridges so as to maintain plastic therein in a molten state without the need for separate heating beyond that derived from said distribution body.