The Study Of Conveying Mechanism And Experimental Study Of Differential Vertical Screw Conveying

With the rapid development of economy,many industries demand for material transportation increases.Material transportation has become an important part of economic development,and the material conveying machinery technology develops rapidly and is applied widely.The vertical screw conveyor is an important material conveying machinery in the material transportation.This paper puts forward the concept of Differential vertical screw conveyor and studied the conveying mechanism and the conveying performance and the similar design theory of it.Differential vertical screw conveyor is different from the traditional vertical screw conveyor.Differential vertical screw conveyor conveys materials through the rotating outer cylinder and the rotating screw and they rotate in the opposite direction.In a broad sense,as long as the mode of transport of the material through the spiral blade or rotation of the outer cylinder or both,all belong to the differential vertical screw conveyor.It is traditional vertical screw conveyor when the outer cylinder rotary speed is zero and the screw rotates.It is also a differential vertical screw conveyor when the screw rotary speed is zero and the outer cylinder rotates.When the helix blade and the outer cylinder rotate in the opposite direction,it is a typical transformation of vertical screw conveyor.The traditional vertical screw conveyor and outer cylinder rotation type of vertical screw conveyor is the extreme form of differential vertical screw conveyor.At present,the traditional type of vertical screw conveyor has been studied deeply,and the relevant information can be fined in the Continuous Conveying Machinery Manual.But there is no uniform model of vertical screw conveyor,and every manufactures respectively set product model.OLDS of Australia has done a lot of studies about casing rotary vertical screw conveyor of simulation and application,but the studies for the conveying mechanism and design theory of it is rare.The differential vertical screw conveyor transformation of vertical screw conveyor put forward in this dissertation hardly has not been studied on its working mechanism,simulation and experiment.In addition,in the design of vertical screw conveyor,screw pitch,spiral diameter,height of conveyor,motor power,material attributes have great influence on conveying performance.It has great need of material resources,financial resources and time to test the influence of the parameters above-mentioned in the case of different collocations.Therefore,this paper analyzesthe mechanism of differential vertical screw conveyor,simulation research,experimental research and search for a more general design theory.This is very necessary.The structure of this paper is as follows:The first chapter reviewed the vertical screw conveyor,the origin,innovation and research route of the topic.First is the initial introduction of screw conveyor,screw conveyor including classification,characteristic and traditional vertical screw conveyor conveying mechanism.Then,elaborates on the working mechanism of the traditional vertical screw conveyor,and review the research status at home and abroad of the vertical screw conveyor,and introduced the parameters of vertical screw conveyor,performance and research methods.At last it introduced the research origin,purpose,significance,contents and methods of the topic.The second chapter studied the working mechanism of differential vertical screw conveyor.At first,described the physical properties,mechanical properties of bulk materials.And then did detailed analysis based on the single point method on the motion state of a particle respectively from the two aspects of kinematics and dynamics,established the mathematical model of the particle.In the third chapter,the soybean transformation in the differential vertical screw conveyor is simulated by the way of discrete element method,and the performance of the differential vertical screw conveying is analyzed.Discrete element method is an effective means of scientific analysis of bulk materials,gradually has been widely applied in granular materials research.This chapter firstly introduces the development of discrete elements and then its basic principle.Constructed the simulation program basing on the research content,and analyzed the simulation results in detail.This paper simulated the process of differential vertical screw conveying having feeding apron and having no feeding apron transmitting soya with different rotating speed collocation of casing and screw,detailed performance analysis of these two kinds of structure transformation of vertical screw conveyor was compared.The simulation results the vertical screw conveyor is feasible;the collocation of outer cylinder speed and screw speed has great impact on the performance of differential vertical screw conveyor and the feeding apron is one of the important factors influencing transport performance.It can replace the horizontal spiral feeder of traditional vertical screw conveyor.Thereby the structure of vertical screw conveyor can be simplified.The fourth chapter conducts the experimental study on the differential vertical screw conveying.The innovation of the differential vertical screw conveying lies in the reverse rotation of outer cylinder and screw.The simulation studies show that the collocation of outer cylinder rotational speed and screw rotational speed has great influence on its performance,so experimental research focuses on the transportation performance influenced by the collocation of casing rotational speed and screw rotational speed.There are two important works in the test process.The first is the design of the kind of vertical conveyor that its screw rotational speed is zero and casing rotational speed is not zero.It is an extreme form of differential vertical screw conveyor.The prototype has been transported the oil shale rock particles to 5.5 m high vertically successfully and the performance is good.The prototype proved that rotating cylinder can be the drive of a vertical spiral conveying for a granular material transportation.The second work is the design of test platform of the differential vertical screw conveying.The test platform must can respectively adjust the outer cylinder rotational speed and screw rotational speed.The rotational speed of screw and outer cylinder is respectively adjusted by the cone pulley.The cone pulley is divided into five.Through the test platform,the influence of the collocation of the outer cylinder rotational speed and the screw rotational speed to transporting capacity and motor power and efficiency were studied.At last a method was proposed that according to the contour of casing rotational speed and screw rotational speed for different parameters.The fifth chapter is based on the similarity theory to establish the similarity criterion of differential vertical screw conveyor.According to the previous three chapters,it can be summarized as follows: first,the size parameters,feeding apron,the casing rotational speed,screw rotational speed,particle characteristics greatly influence the performance of the differential vertical screw conveyor;second,transport capacity,motor torque,transmission efficiency in the design is important to performance.In practical application,the conveyance height,conveyor size parameters,particle attribute do a great influence on the design.And now there is no mature design method.The purpose of the establishment of the similarity criterion of differential vertical screw conveyor basing on the parameters above mentioned is to put forward a designmethod on differential vertical screw conveyor.Adopt the similarity criterion and the data based on the experiment rig in the design of double rotational vertical screw conveyor is not very precise design method,but for the less demanding occasions it is a simple and easy method,and can save a lot of material resources and financial resources.According to the similarity criterion,this paper also put forward the concept of particle similar round.Using similar round method can simplify complex shaped particle to spheroplast with uniform size.So can simplify simulation,and reduce the simulation time.In the sixth chapter,the research work of the differential vertical screw conveyor was summarized,and the future research direction was looked forward.Generally speaking,the main innovations of this paper are as follows:(1)Put forward the method of differential vertical screw conveyor,which enriches the definition of vertical screw conveyor.(2)The transmission mechanism of differential vertical screw conveyor was analyzed.The model of kinematics and dynamics of materials in the process of conveying was constructed.Through DEM simulation studied the granular state in the transportation in the differential vertical screw conveyor.(3)The study on the casing rotational vertical screw conveyor and the differential vertical screw conveyor proved the rotating casing can convey granular material.And analyzed the influence of the rotational speed collocation of casing and screw to transmit mass,power and transmission efficiency.(4)Construct the similar theory of differential vertical screw conveyor,provides a theoretical basis for the design theory of differential vertical screw conveyor.(5)Proposed a similar circle principle,provides a theoretical basis for simplifying the simulation research of the work.