Optimization Design Method For Nozzle

Nozzle plays an important role in the spinning process, and it will greatly affects spinning process and products. Comparing with the technologies of advanced countries,e.g., Japan, USA, our country’s technology in nozzle design fall behind. The main reasons are lack of theoretical analysis. This thesis found that when the spinning speed is higher,the spinning process might deteriorate into invalidity. Additionally a higher spinning speed requires a higher pressure for spinneret, resulting in a large deformation. It requires, therefore, a theoretical analysis for optimal design of nozzlein different working conditions.Firstly, nozzles with various kinds of shape and micro-hole are collected and the rheological state in nozzle is investigated. One dimensional governing equationis derived according to fluid dynamics.Secondly,(1) the distribution of longitudinal speed in nozzle is derived according to the assumption of radial velocity of flow and two dimensionalunsteady incompressible continuous equation. And the distribution of pressure is approximately determined according to Darcy’s law.(2) The location of spinneret holes in inner circle is determined and the radius of the inner circle should meet the radius of the point with highest pressure so as to calculate the relation of radius between the most inner and outer circle. For two nozzles with the same condition, the relation of radius between the most inner and outer circle is direct proportion by controlling the inlet flow rate and spinning speed which means the larger of the most outer value, the larger of the most inner value and the larger of spinning area that can’t use for spinning. Otherwise, the smaller of the most inner value,the smaller of the most outer value which means the spinneret holes and the spinningefficiency will decrease. The optional radius of the most inner and outer circles can be obtained according to this equation.(3) As for the longitudinal structure of spinneret holes,a new composite one to make the pressure gradient to be the maximum is given and horizontal ordinate and vertical coordinate of the transition angle are calculated theoretically.(5) Big nozzles can increase productivity. However, misdistribution of pressure leads to no spinning. This paper explains that why some nozzles can’t work and proposes improvement projects.Finally,(1) according to the investigation of nozzle components, the relation between drop height and the radius of nozzle is calculated by the theory of slab under pressure and the simulating of experimental data. But it need further precise simulating because of the influence of the experimental data volume.(2) The relation between the speed of metering pump, the speed of feeding roller and the pressure of solution is calculated.(3) A patent named “a composite nozzle for spinning with high speed and high efficiency” is completed based on theoretical research.