The invention relates to a spinning unit, particularly for the melt spinning of high polymers, such as polyesters, polypropylene and polyamides, comprising a spinning pump mounted on a pump base and nozzle unit, secured within a housing provided with a heating jacket, the pump base being connected by means of a screw connection to the nozzle unit.
Systems already known include spinning units of the kind mentioned above, in which the nozzle unit and the pump base are screwed together by means of a pressure spindle situated, opposite the sealing surface, in the nozzle housing (Ger. Fin. Discl. 1,660,209). In a construction of this kind the nozzle housing has to take up the reaction forces of the pressure applied and, as it were, "guide them around" the nozzle unit. Heavy constructions are therefore required, rendered still bulkier, for example, by the installation of profile bars. In view of the complicated nature of the spinning units now customary, the necessary reinforcement devices cannot always be attached in the desired manner. Apart from this, an increasing quantity of steel is required, the volume of space available for the heating agent being reduced accordingly. This results in difficulties from the thermal point of view.
In addition, there is a tendency to use increasingly large spindle nozzle plates, of correspondingly ample width, the problems of rigidity thus being aggravated. In this connection it must be borne in mind that the usual spinning pressures are in the range of 500-1000 atm. gauge pressure. This pressure tends to separate nozzle unit and pump base by a force which is the product of pressure and cross-section of connecting ducts. The spindle furthermore has to supply the sealing force which prevents the polymer melt from escaping from between the contact surfaces.
Above all, however, the position and number of the threads in the pressure screws provided in the housing are fixed by the housing, so that changes in the number of nozzle units within the spinning units and the number of conduits for the spinning melt cannot be altered later.