Plastic sheet production equipment is widely used equipment. The pressure distribution along the screw axis is one of the variables in the extrusion process, which can affect the energy conversion and mixing effect. The pressure distribution along the screw axis is related to the screw configuration, material properties, and operating conditions.
When the viscosity of the processed material is wide, in general, in order to obtain a good extrusion characteristic, for different viscosity of the material, the screw is pulled out to study and redesign the combination, in order to obtain suitable for this material characteristic along the screw axis direction of the pressure distribution. As we all know, the disassembly of large-size plastic sheet production equipment is very troublesome, stopping the operation of the screw combination will affect the production, but also waste a lot of time and energy. For extrusion of materials with similar formulations whose working viscosity changes have little relation, In order to solve the problem, the pressure regulating valve can be set on the corresponding barrel along the direction of the screw axis and a specific position. The desired distribution of pressure data along the screw axis can be obtained by adjusting the valve opening without the need to combine the screws.
The working principle of pressure regulating valve is very simple, namely through certain mechanical methods to change the screw due to some of the material flow along the axial area, change the material input mechanical energy (pressure can) and shear strength, to control extrusion process in book design, obtain the best effect of extrusion, change the extent of the screw due to some material filling. When the control valve is opened, the flow area increases and the mechanical energy of the upstream part of the valve is transformed into material pressure energy. When the valve is closed, the mechanical energy of the upstream spiral section of the valve increases the pressure energy and shear energy of the material. When the opening area of the valve is reduced, the filling degree of the upstream material of the valve in the spiral groove increases, and the pressure increases. If the area is aligned with the exhaust port or feed port, it can be used for exhaust or feed. The valve enables online regulation and stable extrusion in the shortest possible time.
The control valve of the working pressure control device of the plastic sheet production equipment can be set at the same time through the head flange between the screw head and the mouth die on the end of the different screw to adjust the pressure of the mouth die; The regulating valve can also be located in a certain part of the screw and the corresponding barrel, in order to adjust the pressure distribution of the section.