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Spiral Drinking Straw Making Machine Poor Plasticization

Hangzhou Newtech Machinery Co.,Ltd | Updated: Nov 02, 2017

Spiral Drinking Straw Making Machine Poor plasticization

Screw beverage straw extruder screw high-speed extrusion of the plasticization of the phenomenon, how to solve the spiral drink straw extruder screw high-speed extrusion when the plasticizing effect:

In order to solve this contradiction, in the past the general approach is to improve the speed at the same time to reduce the depth of the groove, with increased shear effect to ensure that plastic plasticization and homogenization. But it is so dependent that some plastic that can not withstand high shear (such as hard polyvinyl chloride) is easily decomposed and can not be processed in such an extrusion. In order to less the possibility of plastic decomposition Want to strengthen the cooling of the barrel, something to be screwed into the cold water, so dependent on the actual reduction in the amount of extrusion, colleagues also waste heat. And the decrease in the depth H3 of the groove causes the positive flow to decrease and thus reduce the amount of extrusion. These phenomena are contradictory to increasing the speed to increase production requirements. In order to solve this contradiction, for some plastic can also improve the barrel temperature to promote participation in solid phase melting. But this method is limited. Because this way the temperature of the extruded product will also increase, which increases the burden of the host and auxiliary cooling system. The efficiency of the current cooling system is often a major obstacle to limiting the increase in extrusion productivity. Colleagues crowding out the temperature will also lead to products in the cooling process to produce a greater internal stress, which has a greater deformation of those heat-sensitive plastic, or must be processed at lower temperatures extrusion process (such as cross- Foaming, etc.) to increase the barrel temperature is fundamentally undesirable. So now is actually the correct design of the screw to reduce the extrusion temperature, which is some information about the so-called "low temperature extrusion screw. From the melting theory and operation practice we know that the plastic melt in the screw The starting point A and the location of the melting point B are directly related to the screw parameters, process conditions (speed, temperature, head pressure, etc.) and plastic properties. In general, in order to increase the extrusion volume, it is necessary to increase the screw speed n or deepen The depth of the groove H3. However, it is bound to move the positions of the phase change points A and B in the direction of the head. If the aspect ratio L / D is not increased, it is possible to mix the unmelted solid residue , Is the quality of plasticized decline.

The reason for this phenomenon can be analyzed as follows: Since the solid phase does not flow like a fluid, the heat generated by the shear is small. The solid heat source is mainly dependent on the heat source conducted by the heater on the barrel and the heat source in the melting film due to the shear, and its conduction velocity barrel temperature, contact area, plastic porosity and thermal conductivity and other physical parameters related. And when these conditions must be, the screw speed (in fact, represents the plastic to withstand the heating time) will directly affect the thermal conditions. Thus, the former part of the screw, i.e. the feed section and the compression section, must ensure that the plastic has sufficient residence time to heat it into a substantially molten flow state. And then in the measurement section to further withstand the shear, plastic and homogenization to ensure good product quality.

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