Study On The Mechanism And Experimental Equipment For Continuous Metering Of Multiphase Materials For Rubber Mixing

With the development of all kinds of new polymer materials and other high-grade rubber products such as green tires,people are eager to produce rubber of high quality and stability.Higher requirements are put forward for the rubber continuous mixing process equipment,as well as metering system of materials like rubber and carbon black,and thus innovation is urgently needed in the mixing system and mixing process equipment.The traditional way of mixing adopts upstream equipment for the metering and batching of carbon black and other particulate materials,mixer and open mill for mixing.The metering of rubber raw materials and carbon black powder and the processes of the rubber mixing are not continuous,and this intermittent metering method and mixing technology have been very mature.But with the higher demand of rubber quality and production automation,the intermittent metering and mixing equipment can not meet the requirement of product quality and processing technology due to inherent defects,such as the uniform mixing rubber quality,low efficiency,high energy consumption,heat loss and complex mixer system.To solve the shortcomings of intermittent mixing,domestic and foreign scholars have been focusing on the research of continuous mixing process and equipment,which has been greatly improved after years of research.However,due to the viscoelasticity properties of rubber raw materials and the complexity of ingredients,there are still a great problem on the accuracy of the match for continuous metering and feeding of rubber,carbon black and other ingredients.Continuous feeding is mainly realized by processing rubber raw materials into powder or granular,but it difficult to achieve large industrial applications due to the high cost,and traditional metering method and machine can not meet the requirements of continuous mixing production.A new method and new technology for fast and accurate continuous metering has become the urgent problem to be solved.It has very important theoretical significance and application value to develop a new type of automatic continuous feeding and metering system and conduct experimental researches to realize rapid and accurate automatic metering of rubber materials,which can enrich and perfect the theory of continuous metering and mixing.For the above problems,the main research work of this thesis analyzes the performances and physica characteristics of solid rubber,granular powder ingredients and oil materials.And proposes a new mathed for continuous metering method on different types materials,establishes continuous metering and mixing mechanism,develops the intelligent and dynamic feeding and metering system for rubber continuous mixing,and realize the seamless integration with the continuous mixing machine.It also targets the development of an intelligent test platform for continuous metering ratio of rubber raw materials,carbon black,small materials and oil,a truly continuous batching and contiuous mixing experimental equipment.It.The main contents include:1.Based on the study of the working mechanism of automatic metering method about natural rubber,carbon black powder and oil which are of different physical forms,the paper puts forward a new automatic feeding method and new ideas for the feeding system of rubber raw materials,carbon black,small material and oil.And at last it Puts forward a new mechanism of continuous metering and metering of solid-liquid-powder three phase materials,and develops the structural model of continuous mixing and metering of materials.at the same time designs the continuous metering system and structure of multiphase materials.2.Based on the dynamic continuous metering mechanism and continuous mixing mechanism,the dynamic mathematical model of continuous metering is established according to the properties and structural characteristics of rubber and carbon black.Starting from the properties of carbon black and other additives,the paper studies the size and physical properties of the material particles,and then builds the mathematical model of fluidity and accumulation of powder and granule,and finally explores the impact of geometrical nature of particles on the dynamic continuous metering performance.3.Based on systematical analysis of the multi-phase hybrid automatic continuous metering system,it establishes the dynamic equation of continuous feeding of automatic metering device,and studies the influence of material properties on the accuracy and continuity of the batch.The kinetic analysis shows that for the powder material with the angle of repose more than 30°,the mobility is poor and the screw with larger pitch should be selected;for the powder material with the angle of repose less than 30°,the mobility is better and the screw with smaller pitch should be selected.For large and rapid feed carbon black materials in the unsteady state of motion,the response speed,the motor speed and feeding screw diameter should be properly increased;for the small amount of powder feeding in the unstable state of motion,the motor speed,screw diameter and helix angle should be appropriately reduced.Through kinetic analysis,the mathematical model of rubber and carbon black additive ratio are established,and continuous conveying of rubber and continuous metering of carbon black and other additives are achieved.4.Through the study of continuous metering and continuous mixing mechanism,the research adopts EDEM and ANASYS to analyze the dispersity and homogeneity of carbon black and small material in the metering process,and meanwhile,conduct sparticle model analysis,motion analysis,stress analysis and structural analysis of materials and material equipments,and lastly optimizes the design of material conveying and mixing structure.5.Baseed on continuous metering and continuous mixing experiments for materials,developes a hybrid automatic continuous metering and continuous mixing deviceis.Through independent research and development of continuous plastic grinding machine to press the rubber compound into a uniform strip,and the rubber conveying volume is calculated by an encoder to obtain the added quality of the rubber material,and the oil and the carbon black system are mixed with the rubber material'sadded quality to a ratio,and continuous mixing and continuous metering of materials are completed.The hybrid automatic quantitative metering performance and the influence on the quality of the continuous mixing rubber are obtained by studying the properties of the rubber,the energy consumption and the dispersion of carbon black.The ingredients are continuously weighed through three different measuring devices.6.The research uses iterative algorithm to realize PID control and is programmed by LABVIEW to realize closed loop control of multi-material continuous metering system.and the continuous metering and continuous mixing can be controlled on the same control plat form to improve the metering accuracy.Quantity,continuous mixing the overall performance.The multi-phase continuous metering system was validated and optimized by metering stability test and continuous mixing performance test.7.The experiment of physical properties stability shows that the adding time of carbon black additives is delayed than the adding time of rubber raw material,so it is necessary to realize proportioning speed of automatic metering device according to the mixer speed and optimize continuous metering control systemby eliminating the time lagcaused by error of adding,The adhesive density error is controlled at 0.3%.8.For the continuous mixing experiment platform,the optimum conditions of natural rubber mixing are as follows:The screw speed of the extruder is 30 r / min,and the barrel temperature is 60°C while the temperature of the head is 70°C.Experiment data show that the mechanical properties of the continuous mixing such as Mooney and shear modulusis equal to or greater than that of traditional mixer,while its tensile strength is slightly stronger and tear strength enjoy sobvious advantages.Although the dispersion degree is lower than that of the intermittent mixing,the dispersion stability of continuous mixing has a very significant advantage,which indicates that the use of continuous metering and continuous mixing process can improve the stability of rubber quality.Through theoretical analysis,computer simulation and experimental research,the paperis able to establish continuous metering system for solid-powder-liquid three-phase material,enrich the material dynamic continuous metering theory,and improve the rubber continuous batching and continuous mixing process equipment.Relevant experiments are then carried out to further prove the feasibility of the three-phase dynamic continuous metering theory and experimental scheme and the feasibility of the dynamic continuous metering system and its experimental device.It is of important theoretical significance and engineering application value for industrial ingredients and rubber continuous mixing industry.