Flanging and Hemming of Auto Body Panels using the Electro Magnetic Forming technology
Electro Magnetic Forming (EMF) technology has a great number of potential applications for the automotive industry. LABEIN-Tecnalia has worked with this technology for six years and has a good understanding of the automotive industry’s needs and challenges. LABEIN-Tecnalia is currently developing new applications with EMF technology. Taking into account the advantages and limitations of EMF, bending and hemming processes present good geometric conditions for the use of this technology. The study presented is based largely on hemming circular configurations which are simplifications of those commonly used on hemmed automotive parts. The parameters of this new EMF bending and hemming processes have been studied, as well as their influence on the final quality of the parts obtained. Conclusions obtained from the basic geometries were tested on a more complicated geometry in order to apply the knowledge acquired. Parallel to the experimental work, fully coupled electromechanical software by LS-DYNA has been used to simulate and extend the present hemming results.
Sharp flanging and flat hemming of aluminum exterior body panels
Limitations of conventional flanging and hemming technologies require increased radii of flanges and roped hems when aluminum alloys are used for production of closure panels. A new process of flanging has been developed based upon the idea of redistributing plastic strains through the larger area, delivering additional metal into the bending zone, and creating an additional axial compression. Comparison of the newly developed and conventional flanging process indicated that the new process expands the bending ability of aluminum alloy 6111-T4 by allowing an additional 10% of prestrain to the panel compared with previous forming operations. The advantages of the new flanging operation can be transferred to the hemming operation by allowing an additional 10% of prestrain through the whole sequence of forming and assembly operations. Employment of suggested flanging technology makes possible the flat hemming operation of panels stamped from aluminum alloy 6111-T4 if the thickness of the interior panel is 1 mm or more.
Determination of Optimal Ball-Burnishing Parameters for Plastic Injection Moulding Steel
The objective of this study is to determine the optimal plane ball-burnishing parameters for plastic injection moulding steel PDS5 on a machining centre by utilising the Taguchi’s orthogonal array method. The design and manufacture of a burnishing tool are described. Four burnishing parameters, namely the ball material, burnishing speed, burnishing force and feed, were selected as the experimental factors in Taguchi’s design of experiments to determine the optimal burnishing parameters which have the dominant influence on surface roughness. The optimal burnishing parameters were found after carrying out the experiments specified by Taguchi’s L18 orthogonal table, by the analysis of variation, and by a full factorial experiment. The optimal plane burnishing parameters for the plastic injection moulding steel PDS5 were a combination of a tungsten carbide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N and a feed of 40 μm. The surface roughness Ra of the specimen can be improved from about 1 μm to 0.07 μm by using the optimal burnishing parameters for plane burnishing.