Manufacture of synthetic continuous polyester or polyamide yarn, by melt spinning at high drawing speeds, achieves ultra fine dimensions and low breakage rate, in light of mathematical understanding of process and materials variables

摘要

Of the two or more injection points (3.1, 3.2) located close to the injection molded part, one (3.2) is positioned near the gas injection nozzle (4). An Independent claim is included for the corresponding method. The direction of expansion of gas bubbles, and the flow direction of mass injected at the injection point (3.2) near the gas nozzle (4), are the same. Preferred features: Other injection points (3.1) are so positioned, that they support the flow of injected mass from the injection point (3.2) near the gas nozzle (4). There are two temperature-controlled water (cooling) circuits (6, 6.1). Of these, one is located under the injection point (3.1) remote from the gas nozzle (4), and also along the volume where plastic accumulates, to be displaced by the bubble. The mold can include several gas nozzles (4). In the method, ejection of the injection molded part, is induced by the pressure in the gas bubble itself. The quantity of plastic mass injected is less in volume, than that of the bubble (4.1) produced. The mold is precooled up to the end of the dosing operation using the water circuit (6.1). When the plastic has been dosed, an unfilled volume is left in the mold (1), in the direction of bubble expansion.