| 摘要 |
<p>This invention relates to a novel apparatus adapted to feed to a mold from an extruder, a plastic synthetic material containing a foaming agent. The apparatus comprises a channel for transporting the material from the extruder to the mold, a nozzle having an opening therein, the nozzle forming a part of the channel, a nozzle needle which is moveable through the nozzle opening, the front surface of the needle adapted to close the nozzle opening, a heating element which maintains the needle at a high temperature, a cooling system which maintains at least a part of the inner surface of the channel at a temperature below that of the needle, and a carrying means adapted to open and close the opening by moving the needle. The apparatus of the present invention provides a simple and inexpensive device for use in an injection molding process for charging a mold, producing a stream of synthetic material which at the exit of the nozzle and at the entrance to the mold has an outer limiting zone which does not foam, and in the central region of the stream, foams in the normal way. These devices have hithertobefore been unknown.</p> |
