The Design Of Vertical Measuring Device And Experimental Study Of Dynamic Friction Coefficient Of Powder Materials

In this paper, considering the influences, such as pressure, temperature, speed that may be related to the practical production, I design a vertical measuring device to measure the dynamic friction coefficient of powder materials. With the design of the hydraulic system, temperature control system, and the use of machine like motor, buncher etc, to realize the function of setting different pressures, temperatures, rotating speeds, and the use of the Lab VIEW data acquisition software and the NI data acquisition card to complete the collection and storage of required data in the process of experiments in real-time.The main structures to measure the friction coefficient,3 kinds of friction structure have been designed. Structure 1, the shaft rotates to drive the powder material rotates synchronously, so that the friction happens between the powder material and the cylinder wall; structure 2, the cylinder will fix the powder material so that the friction between the powder and the axis; structure 3, using the relative motion between plane disc and powder materials to determine dynamic friction coefficient. Select the relatively common polymer materials, such as waste rubber powder, polypropylene (PP), and polyvinyl chloride (PVC) to experiment respectively in the 3 kinds of the structure, to verify the feasibility of the design of the structure.Through the experimental comparison, considering choosing the more reasonable structure, structure 1, to experiment again. The material is rubber powder and pretreated rubber (with tall oil), which are used in the project, the source of this research. Complete the measurement of dynamic friction coefficient in different experimental pressures, temperatures, speeds. Then analyze the change law of the rubber powder about its friction coefficient in different experimental conditions, which can provide reference data to the design and the selection of the structure and machine used in the project.Through the observation in the experiments and the analysis of a large amount of data draw a conclusion that the change of the pressure influence the friction coefficient of powder material, under normal circumstances, the friction coefficient decreases with pressure increases; the influence of temperature change depend on the powder materials, which is associated with the physical properties of powder material itself; the influence of the change of speed is more complex, because the speed change usually can cause the generation of heat by friction, the particle size become smaller in shear and other changes; in addition, through the comparison experimented on the structure 3 draw that the layer thickness of powder material also affects on the determination results. Therefore, the dynamic friction coefficient of powder materials is affected by actual pressure, temperature, rotating speed, material properties and other factors.