Hot runner system for injection molding machine

A nozzle combining structure for a hot runner system for an injection molding machine comprising:

• a manifold having a resin injecting hole extending therethrough in its inner portion through which a resin flows and a nozzle seated groove formed in an outer peripheral surface of an end of the resin injecting hole, a nozzle being seated in the groove;
• a nozzle having a piston guide bushing formed at its upper end inserted into the nozzle seated groove of the manifold, for dispensing the resin injected from the resin injecting hole of the manifold through the piston guide bushing into a mold;
• a manifold guide bushing for surrounding and threadedly engaging with an upper portion of the piston guide bushing of the nozzle, the upper end of the manifold guide bushing having a flange with an external diameter smaller than that of a diameter of the nozzle seated groove of the manifold to form a first expansion chamber therein whereby when the manifold thermally expands, thermal expansion of the manifold in the axial direction is accommodated within the first expansion chamber;
• and
• a fastening bushing for receiving an outer surface of the manifold guide bushing and threadedly engaging with an inner circumferential surface defining the nozzle seated groove of the manifold so that the manifold guide bushing is fastened by the fastening bushing to the inner circumferential surface defining the nozzle seated groove of the manifold, and a second expansion chamber formed along a longitudinal length between the fastening bushing and the manifold guide bushing, whereby when the manifold guide bushing thermally expands, thermal expansion of the manifold guide bushing in the axial direction is accommodated within the second expansion chamber.