| During the operation of the pipe conveyor,the contact area of rollers and belt would generate force in both the normal direction and the tangential direction.In the engineering design,the normal force of the roller is called as roller normal pressure,the tangential direction of the belt is called as sag resistance.The roller normal pressure is the key parameter in the roller structure design,sag resistance is an important design basis in the motor driving force and type of belt for pipe conveyor.In the engineering design,Design basis for a single roller structure is based on the sum of forming force of the belt,the gravity of the belt and the gravity of the material between the two roller group.It would result in excessive volume and mass of the roller.The sag resistance is still referenced to the sag resistance coefficient of ordinary conveyor,due to the working principle of the two belt types are different,which leads to the difference between the calculated value of the belt sag resistance and the actual situation.In order to optimize the calculation model of the roller normal pressure,research influence of the normal pressure and the radius of the roller on the sag resistance,in this paper,the FEM model of belt-roller is established for pipe-shaped belt with diameter of 150 mm,the transient dynamics analysis is carried out,the influence of different factors on the normal pressure and the sag resistance of the roller is studied.The experimental device of the pipe conveyor is built to test roller normal pressure.The main research work of the thesis is as follows:(1)The composition of the roller normal pressure is analyzed,and decomposed the roller normal pressure three components related to the forming force of the belt,the gravity of the belt and the gravity of the material.Considering the difference positions of the six rollers in the rollers,the coefficients of the three components in the normal pressure of each roller is studied.Firstly,the influence of material filling rate and density on the gravity component of the material is studied based on the FEM,and the coefficient function of the gravity component of each roller material is obtained.Secondly,based on the belt-roller FEM,considering only the gravity of the belt,the gravity component of the belt in the normal pressure of each roller is studied,and coefficient of gravity component of the belt is obtain.Finally,based on the conveyor belt-roller FEM,considering only the forming force of the belt,the forming force of the belt on the normal pressure of each roller is studied,and the coefficient of the belt forming force of on the normal pressure of each roller is obtained;and then,the normal pressure calculation model of the roller at six different positions in the rollers is obtained.(2)The influence of the rollers normal pressure and the roller radius on the sag resistance is analyzed.Firstly,the influence of the rollers normal pressure on the sag resistance is studied.The influence of the normal pressure of the rollers on the sag resistance is divided into the influence of the rollers spacing,the material filling rate and the material density on the sag resistance.The relationship between the sag resistance and the rollers spacing,the material filling rate and the material density is obtained.The relationship between the normal pressure of the rollers and the sag resistance is also obtained.Secondly,the influence of the roller radius on the sag resistance is studied,and the influence law of the roller radius on the sag resistance is obtained.The relationship between the roller radius and the indentation resistance under different rollers normal pressures is studied.The relationship between the sag resistance and the positive pressure of the roller set and the roller radius is obtained.(3)The experimental device of the pipe conveyor and test program of roller normal pressure is designed.The roller normal pressure under different material filling rates is tested based on the experimental device,and compared with the calculation model of roller normal pressure,the normal pressure calculation model of the roller is verified. |
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