Die plates are designed using Finite Element Analysis (FEA) and Fluent simulation technology, with structural optimization points such as: eyelet design, material, temperature control simulation, and melt flow simulation.
Of course, this is not the solution to all the problems, the finish of the granulation belt, the finish of the inner wall of the die hole, the selection of the material and so on, relying on our professional equipment and experience accumulated.
We start with an introduction to design optimization:
Mold Holes Design And Spacing:
According to the specifications of the granulation requirements, the general diameter of the hole 0.5 ~ 5mm, the layout of the mold holes, the main rules, such as round, rectangular or polygonal. Mold holes spacing, designed to prevent the melt material in the die plate to prevent retention, to ensure smooth and take into account the stability of the pelletizing. Therefore, the fluidity of the melt material, the output of underwater pelletizing, the shape and quality of the pellets, all of these factors can be simulated by Fluent simulation technology. The final result we want to achieve: uniform distribution of the mold holes, to achieve the set output, to ensure the stability of the melt extrusion, pelletizing effect is good.
Die Plate Body Material:
Die plate composition: template and granulation belt. The material of the template, tool steel or stainless steel. The material of the template needs to be resistant to high temperature, high pressure, corrosion, and welding fusion with the pelletizing belt. Please note that the welding with the pelletizing belt is vacuum brazing, and after welding, the strength, weld fusion, and densification are factors that affect the length of the pelletizing template in the long term. We have simulated the vacuum brazing of a variety of wear-resistant materials to stainless steel through actual tests as the basis data for our Fluent analysis.
Material Of The Granulation Belt:
TiC-NiGr, TiC-Fe, WC-Co and other metal-ceramic materials are mainly used. They are used in various brands of underwater pelletizer. We analyze them one by one.TiC-Fe metal ceramic, vacuum welding effect is good, but heat resistance and corrosion resistance is poor.WC-Co metal ceramic, vacuum welding technology is difficult, corrosion resistance is good, heat resistance is poor.TiC-NiGr metal ceramic material, vacuum welding effect is good, corrosion resistance and heat resistance is good. Through the type test and Fluent analysis, TiC -NiCr and 1Cr13 stainless steel welding effect is the best, welding tensile strength is not less than 300 MPa.
Vacuum Brazing:
We have used a variety of material tests and found that copper-based brazing materials, protected by nitrogen in a vacuum brazing furnace, provide the best high-temperature fusion and stable densities.
Temperature-Controlled Simulation:
The die plate contains a heating channel and a melt channel. The melt channel is for the entry and exit of the molten material and the hot channel is for the entry and exit of the heating medium, conventionally thermal oil, water and steam are used. The hot channel is distributed around the melt channel to regulate the temperature of the melt channel and ensure the stability of the melt material during extrusion. Temperature control is at the heart of the die plate. The arrangement of the hot channels and the flow rate of the heating medium combine to regulate the temperature of all melt channels. Using Finite Element Analysis (FEA) and Fluent simulation technology, simulate the heating of the die plate, focus on the analysis of the location of the temperature anomaly, optimize the layout of the hot channel and hot channel local design. Corrections are made in advance through design to avoid uneven heating and unstable temperatures during actual production.
