Hot sprue system for diecasting

A sprue insert-set for use in defining at least a portion of the melt flow path in a high-pressure, hot-chamber diecasting apparatus between an injection nozzle and a runner channel formed between the parting faces of a fixed and a moving die, the sprue insert-set comprising:

• a tubular sprue body insert for mounting in the fixed die and a sprue tip insert for mounting in the moving die in opposed relation to said body insert;
• said body insert having a sprue channel extending therethrough, an outer end defining an inlet opening to the sprue channel, an inner end defining an outlet opening to the sprue channel
• heating means for heating said sprue channel,
• a first curved groove formed in said inner end of said body insert leading from said outlet opening of the sprue channel;
• and said tip insert having:
• an inner end adapted to mate with the inner end of the body insert,
• a second curved groove formed in the inner end of the tip insert of complementary form to said first curved groove in the inner end of the body insert such that, when the inner end of the tip insert is mated with the inner end of the body insert, said first and second grooves cooperate to form a curved transition channel for connecting the outlet of the sprue channel to the runner channel when the body insert is mounted in the fixed die, the tip insert is mounted in the moving die when the dies are closed, and
• cooling means for cooling said second curved groove.