| The double screw conveyor is a promising material conveying and mixing machine.It is widely used in modern industrial production and transportation processes,and is generally applicable to industries such as chemical industry,building materials,machinery manufacturing,coal,food,and medical treatment.At present,single screw conveyors are mostly used as research objects.Compared with single screw conveyors,double screw conveyor has a more screw action,resulting in more complicated collision impacts between internal particles.Among them,The interaction of the two helix blade wheelbases has a greater influence on the transport characteristics of the particles.Although the double screw conveyor and the single screw conveyor have certain similarities,they are different in terms of conveying efficiency,stress and wear.In view of the above problems,the discrete element method is used to study the material transport characteristics of the double screw conveyor and the particle force and screw blade wear under the influence of different parameters.Using the Hertz contact theory,the influence rule of the two screw conveyor's wheelbase and tilt angle on the material conveying characteristics was analyzed.On this basis,the contact force of the particles in various parts when the materials are transported inside the conveyor is studied.Then the Hertz-Mindlin with Archard Wear contact model is used to give approximate geometric surface wear depth values for the equipment wear area,and to study the wear of the conveyor blades under the influence of different conveyor structures.Its main work and content are as follows:(1)The material conveying process of the double screw conveyor was simulated and analyzed by using EDEM software.At the same time,the influences of the wheelbase between the twin screws,the Angle of the conveyor,the pitch and the speed on the material transportation are considered.The results show that with the increase of rotating speed and pitch,the average mass flow rate of the material increases and the conveyor's conveying capacity becomes stronger.With the increase of the tilt Angle,the average mass flow rate of the material drops sharply due to the backflow phenomenon of the double screw conveyor under the influence of the wheelbase size.Therefore,the non-meshing double screw conveyor is not suitable for the transportation working environment with a large tilt Angle.(2)By comparing and analyzing the force of particles in the conveyor through simulation,the tangential force and normal force between particles are obtained,and the force of particles inside the conveyor under the influence of different structures is analyzed.As the wheelbase increases,the particle force in the central region gradually decreases.As the tilt Angle increases,the particle force in the central position of the two blades of the double helix conveyor will also increase,while the particle force in the upper part of the conveyor will gradually decrease.These parameters are generally not obtained in the experiment,which can provide a reference for the selection of the working conditions of the double screw conveyor.(3)Research in different wheelbase and double screw Angle,the accumulation of material on the blade wear depth and wear force analysis,and carries on the simulation of different leaf area,get the blade wear mainly concentrated in the blade tip,along with the rising of the conveyor wheelbase,spiral blade wear depth decreases,mesh machine blade wear greatly influenced by the change of the Angle,the mesh type blade wear rate affected by the Angle change is small,can provide certain reference for conveyor structure design. |
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