Research Of Control Technology Of Molding Process Of WPC Co-extrusion

In the process for the production of plastic profile extrusion method of wood plastic composite,the fusion of the polymer melt from the extrusion die covering wood and control of cooling process, determines the quality and performance of wood-plastic composite materials. The control process of wood plastic composites includes extruder control, timber transport control and cooling process is the process of a system, an important working procedure of unit is achieve the uniformity and stability of velocity field and temperature field of extruder control, therefore, a series of studies.This thesis combined with the national science&technology pillar program during the12th five-year plan period "the research and demonstration of key technology manufacture of wood plastic composite"(2012BAD32B04)and "forestry industry research special funds for public welfare projects"(201204802),focusing on process control of WPC extrusion, this paper studied from the angle of WPC melt and process characteristics of extrusion molding, to get distribution curve and process threshold value of mould segment in flow field (temperature field, pressure field) of melt and screw speed (velocity). numerical simulation on flow field of some typical working conditions of WPC extrusion, by constructing three-dimensional computational modelling of the metering section and flange of single screw extruder, experimental results show that heating temperature little influences flow field while revolving speed greatly influences flow field with screw speed increases, pressure of metering section decrease, shear rate increases and viscosity decrease, under the condition of process threshold. Secondly,through analysis and restructure for the model of extruder temperature, developed a fuzzy adaptive Proportion-Integration-Differentiation (PID) temperature control system for wood-plastic extruder. According to measured temperature distribution curves, a temperature model for the barrel was established by parameters identification.Finally, The wood plastic composite co extrusion process control on synchronous control of extruder rate and wood movement rate, adaptive fuzzy PID algorithm is applied to the wood plastic co-extrusion molding control system, thus to the whole model of wood plastic composite material extrusion system control. Research results show that, the study for the rational design of wood plastic composite extrusion structure, provide help optimize channel parameters, provides the control method is better and wood plastic co-extrusion extruder control system.