Tool heat control in injection moulding appts.

摘要

To heat the tools for an injection moulding assembly, the heating is in two stages with different temp. conditions, for the starting phase and the static working phase. The starting phase ends when the temp. initially reaches or exceeds the nominal tool temp. The tool temp. is measured continuously during the whole cycle time at a geometrical centre point between the mould part contour and the coolant channels/surfaces and between the coolant entry and exit at a point sufficiently displaced from the mould contour. At a time point set by a machine control signal, a coolant pulse is generated at a time close to the injection action related to the heating during the previous cycle, to give the required heating during the time span of the max. temp. difference between the injected molten material and the cooling channel. Further coolant pulses are generated through an actual/nominal comparison up to a second time point if the nominal temp. is exceeded, with the second time point set by a machine control signal, close to the end of the cycle.