The Hydrodroforming Process of an Automotive Part Aminu
Tube hydroforming (THF) is currently an active area of development in the automotive industry on account of its advantages it offers in comparison to other manufacturing processes. In this paper, four simulations were carried out having the same cross sectional area but different axial feeding and load paths to improve the process design in THF process, in order to help establish the feasibility of the THF processes for specific components and have the potential to reduce the number of forming trials required to standardize the process for production of high quality hydroforming components.In addition, the studies also focus on development of an experiment simulation procedures for the entire hydroforming process. The simulation results focus on the % reduction thickness. It has also focus on the axial feed and load paths which becomes an important and useful method for planning the process design analysis, design of forming process and also planning of the tool. Since they play an important role and also determine accordance of forming limits such as wrinkling, bursting and crushing .The geometry model is analyzed base on different axial load and load paths. The key issues include geometry modeling, materials selection, meshing, boundary conditions, load definition and contact between the tube and the dies.On the base of the simulation, an optimized process parameter combination has obtained and has been verified by the instrument panel frame hydroforming experiment. The works show that:
Analysis of thinning at the transition corner in tube hydroforming
Abstract In tube hydroforming, the pressure for forming a small corner is far greater than other positions and thinning or cracking often occurs at the transition region between the corner and a straight side. To reveal the reasons of the local thinning and provide the clues to avoid the defect at the transition region, the stress distribution and deformation pattern of the corner are analyzed by mechanical analysis and numerical simulation. The effect of the friction coefficient on stress distribution is also considered. The material at the transition region much more easily satisfies plastic yielding conditions and produces compressive strain through the thickness. Therefore, severe thinning deformation easily occurs at the transition region. When the ratio of wall thickness to the corner radius is greater than 0.5, the difference of yielding conditions between the straight side and the corner is significant enough to induce serious deformation nonuniformity, even excessive thinning.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.