The control system of plastic pelletizing machine includes heating system, cooling system and process parameter measuring system, which mainly consists of electrical appliances, instruments and actuators (i.e. control panel and operation desk). Its main functions are: to control and regulate the dragging motors of the main and auxiliary machines, output the speed and power in accordance with the process requirements, and enable the main and auxiliary machines to work in coordination; to detect and regulate the temperature, pressure and flow of plastic in the extruder; to realize the control or automatic control of the whole unit.
The electrical control of the extrusion unit is roughly divided into two major parts: transmission control and temperature control, to achieve the extrusion process including temperature, pressure, screw rotation, screw cooling, barrel cooling, product cooling and outside diameter control, as well as traction speed, neatly line up and to ensure that the wire collection plate from empty to full plate of constant tension on the wire collection control.
1. Extruder host temperature control wire and cable insulation and sheathing plastic extrusion is based on thermoplastic deformation characteristics, so that it is in the viscous flow state. In addition to the requirements of the external heating of the screw and barrel to the plastic to melt extrusion, but also take into account the screw extrusion of plastic when its own heat, so the host temperature should be considered from the whole, both to consider the heater heating on and off, but also to consider the screw extrusion heat overflow factors to be cooled, to have effective cooling facilities. And require a correct and reasonable determination of the location of the measuring element thermocouple and installation method, can be read from the temperature control instrument accurately reflect the actual temperature of each section of the host. As well as the requirements of the precision of the temperature control meter and the system with good cooperation, so that the stability of the fluctuations of the entire host temperature control system to achieve the requirements of various plastic extrusion temperature.
2. Peal extruder pressure control in order to reflect the extrusion of the head, the need to detect the extrusion of the head pressure, because the domestic extrusion machine does not have a head pressure sensor, is generally the measurement of the screw extrusion after the thrust instead of the head pressure measurement, screw load table (ammeter or voltmeter) can correctly reflect the size of the extrusion pressure. The fluctuation of extrusion pressure is also one of the important factors that cause unstable extrusion quality. The fluctuation of extrusion pressure is closely related to the extrusion temperature, the use of cooling devices, the length of continuous operation time and other factors. When the abnormal phenomenon occurs, can exclude quickly, must re-organize the production should be decisive stop, not only can avoid the increase of scrap, more can prevent the occurrence of accidents. Through the detection of the pressure gauge readings, you can know the pressure state of the plastic in the extrusion, generally take after the thrust limit value alarm control.
Post time: Feb-17-2023