Structure Optimization Of Arc Wing Plate Taking Granules Device Of Vertical Screw Conveyor

Vertical screw transportation is a kind of efficient and clean continuous transportation mode,which realizes the vertical transportation of bulk cargo through the friction between materials,spiral blades and outer cylinders.The screw unloader with its core technology is widely used in port unloading operations.The taking granules device provides a stable material flow for vertical screw transportation,and its taking performance directly affects the efficiency of ship unloading,which is the focus of the research and design of screw ship unloader.In this paper,taking the arc wing of taking granules device as the research object,based on the mechanics of granular media,through the dynamic analysis of the flow law of the granular material in the process of taking,the theoretical taking model of the arc wing is established,and the discrete element simulation is carried out for the structural parameters of the taking granules device that affect the taking amount obtained from the theoretical model analysis,which reveals the effect of the structural parameters of the taking granules device on the taking characteristics.In addition,a simulation study on the wear characteristics of the taking granules device is carried out to provide theoretical and simulation test basis for the structural design and performance optimization of the arc wing plate taking granules device.The main contents and conclusions are as follows:(1)Starting from the geometric structure of the taking granules device and based on the theory of mechanics of granular media,the movement process of the bulk particles entering the spiral inner cylinder from the outside through the taking granules device is analyzed,the dynamic conditions of the bulk particles entering the spiral inner cylinder in the taking granules device are deduced,and the theoretical calculation model of the taking efficiency of the taking granules device is established.The results show that the maximum circumferential pressure of the particles close to the arc wing plate in the taking granules device is easy to enter the inner cylinder;the circumferential pressure of the materials when entering the inner cylinder is affected by the curvature radius of the taking wing plate,the central angle of the arc surface,the opening angle of the inner cylinder and the taking speed;the increase of the depth of the taking granules device buried in the material pile will increase the circumferential pressure of the bulk materials in the device,which will help to overcome the feeding resistance(2)Based on the theoretical model,the single factor discrete element simulation test is carried out to study the influence of the height,curvature radius,center angle of curved surface,opening angle of inner cylinder feeding and rotating speed of the taking granules device on the dynamic characteristics of conveying mass flow rate,vertical lifting speed of particles,peripheral speed of particles,and to obtain the optimized size of the taking granules device structure.The simulation results show that when the height of the taking wing is set to the same pitch as the inner spiral blade,the part of the taking granules device embedded in the material pile can not only ensure the sufficient feeding but also control the particle escaping;the taking amount of the taking granules device is affected by the radius of curvature of the taking wing,and the good taking effect can be obtained when the ratio of the radius of curvature of the taking wing to the radius of the spiral blade is 0.7;When the central angle of the arc surface of the taking wing plate is set to 107°,the arc surface and the material particles are in full contact and the taking efficiency is high;for the taking granules device with three openings,when the angle of the inner cylinder feeding opening of the taking granules device is set to 70°～80°,the particles escape less and the effect of taking is the best;the rotating speed of taking granules device will affect the effect of taking,and the greater the rotating speed of taking granules device is,the more obvious the effect of agitation of surrounding materials is.The rotation of the taking granules device has obvious effect on the agitation of the surrounding material particles,and the excessive rotation speed will affect the reclaiming effect.The rotation speed of the taking granules device should be gradually reduced after the material pile falls.(3)In view of the wear problem caused by the long-term collision and friction between the taking granules device and the material,the wear distribution and the cause of wear of the taking granules device are analyzed by using the discrete element method.The results show that the parts near the inner cylinder of the spiral are most prone to wear,which is mainly caused by the tangential force and relative sliding motion of the material to the parts;through the calculation of the energy of the taking process,it is found that most of the work done by the taking granules device is converted into friction heat,and a few of it is converted into the kinetic energy and potential energy of particles;the taking speed is different The wear condition of the device is studied.It is found that with the increase of the speed of taking,the cumulative contact energy of the taking granules device increases,and the wear speed is accelerated.Two kinds of improved structure types are proposed for the easily worn parts of the taking wing plate in the wear simulation test,and the corresponding simulation test is carried out.The test results show that the wear area of one type of taking wing plate decreases,and the wear speed is faster 68.8%reduction before improvement,and the taking performance is not affected.