Numerical Simulation And Experiment Research Of Copper-based Powder Compacting Process

In this thesis, MSC.Marc software, a finite element simulation software with a good performance in the field of non-linear analysis, was used to simulate the compacting process of the copper-based powder. A test device to measure the friction coefficient change curves in the copper-based powder compacting process was established, and the curves were importing into the following finite element analysis model.The simulation results indicated that the relative density distribution of the green compact was determined by the displacement lag effect induced by the die wall friction in the compacting process. Relative density distribution of the green compact has a similar feature as the law of powder's displacement in the compacting process. With the reduction of the compacting speed, the deformation of green compact and the density decrease were improved obviously.With the establishments of the two-dimensional finite element models, we focused on the copper-based powder compacting process of the main affecting factors. The research showed that improving the lubrication condition can significantly reduced the adverse effects caused by the particles displacement lag effect; When the powder body height to diameter ratio H/D≤1.5, the relative density distribution of the green compact is more uniform. When H/D>1.5, its density distribution is poor, especially when H/D≥4, the density difference is so large that it is likely to cause weakness of the green compact cracking or even collapse; The higher compacting speed is easy to get a green compact with more uneven density distribution. Transformation of the compacting mode can change the distribution of density, bi-directional compaction is better than one-way compaction to get more uniform compacts. After the compaction of the powder, packing a certain time can give a good reduction in the adverse effects of the elastic aftereffect. Reasonable stripping mode can give some help to get a compact of a uniform density distribution. The results show that top-out stripping mode is more reasonable than the depressed type.The thesis focused on the cylindrical powder metallurgy products and had a in-depth analysis on their production processes. We established nine kinds of different programs to study the factors that affect the products compacting processes. The research showed that the bi-directional compaction, with the same upper-lower compacting speed, could get better uniformity of the green compact. Using bi-directional compaction with floating mandrel, the upper-lower compacting speed ratio is 10/1, could get the green compact with more uniform density distribution than the bi-directional compaction with the same upper-lower compacting speed. Using one-way compaction with a floating mandrel, its diewall friction is harmful, the friction of the mandrel is beneficial on the compacts density distribution. However, too much rougher surface of the mandrel also makes the uniformity of the green compact decreased.