The Stress Analysis Of Pellets And Extrusion Mold During The Extrusion Process In The Double Die Mold

Biomass is the only renewable carbon source.It is not only an alternative way to replace the traditional energy,but also a way to improve the environment.So countries around the world attach great importance to developing biomass densification technology.But the technology still has many bottlenecks,such as wide ranging product quality,ring mold scrap rate,higher production cost and energy consumption.The research of particle and extrusion die stress to improve product quality and increase service life of loop die is necessary.The double die pellet machines densification technology of biomass is the research object in this paper.From the structure,process,working principle to introduced its advantages relative to conventional pellet machines.At the same time it was analyzed about the form and reasons for the failure of loop die.This paper conducted the simulation and analysis for the briquetting process through the software of ANSYS.The results indicate that the reason which leads to the crack and loose of the final pellets is because the biomass'rheologic rate at the radial direction is different through the mechanism of the stress analysis between the pellets of biomass and the die holes.The failure of the loop dies comes from two aspects:one of them is that the uneven stress of the pellets make the pellets partial hardening which leads to the abrasive wear to the mold;the other is the fatigue wear between the cone area and the keeping region of the mold.This paper studied the three different model tapers of 30°,45°,60° respectively and the influence of the mould and the loads on briquetting effects is studied by optimization analysis.It can not only improve the final pellets quality but also decrease the serious abrasions on the mold by using the 45° taper model.The 45° taper model has been optimized by arc transition.The results suggest that it can decrease the friction between the cone area and the keeping region and makes the distribution of the stress more homogeneous which relieves the fatigue wear of the region.The simulation research can provide the theoretical basis for improving the briquetting quality and increasing the service of ring die through the stress analysis of the pellets and extrusion die by the software of ANSYS.It can also provide the theoretical basis and reference for the optimization analysis of the model.