Roller contact force for straight section of pipe conveyor considering material factors

The roller contact force is a key parameter for the roller structure design of pipe conveyor. In the engi-neer- ing design,the total contact force of roller group is estimated roughly by calculating the sum of the forming force of belt,the gravity of material and the gravity of the belt between two roller group. The total contact force multiplied by empirical safety factor is regarded as the structure design basis of single roller. The roller contact force is not accurate enough. In order to improve the calculation accuracy,the contact force is decomposed into three components related to the gravity of material,the forming force of belt,and the gravity of belt. It is also calculated separately considering the difference in the position of six rollers in the roller group. The straight section of a pipe conveyor with a diameter of 150 mm is taken as an example to study contact force,and the specific research process is as follows:firstly,the influ- ence of material factors on the contact force is studied by the dynamic model of belt-roller which is based on the finite element method. The proportion of material gravity on each roller is obtained by the variation law of contact force under eight material filling rates. The result shows that when the material filling rate is greater than 50% ,the rollers on lower side are subjected to about 33% to 34% of material gravity,and the bottom roller is subjected to about 60% of materi- al gravity. Secondly,the variation law of contact force under five material densities is modeled by dynamic model. It shows that the influence of density on contact force is weak and can be negligible. So the calculation formula of the ma- terial gravity component is obtained based on above analysis. Thirdly,the effects of gravity of belt and forming force of belt on the contact force are studied. Two belt-roller dynamics models of belt-roller are established,which are only con- sidered the forming force of belt and the gravity of belt respectively. The result shows that the rollers on the lower side are subjected to about 32% of belt gravity,and the bottom roller is subjected to about 70% of belt gravity. The forming force component of the belt on the lower five rollers are close,and the top roller is subjected to the largest forming force component of belt,which is about 1. 49 times than the average value of lower five rollers. The calculation formula of contact force of each roller is obtained by combining with three components of contact force.