AUTOMATION OF SHEET METAL COMBINATION DIE DESIGN PROCESS

This paper proposed a novel methodology for designing and manufacturing of sheet metal dies based on features of sheet parts. Also, combination is designed according to die cupping and punching features of sheet metal parts. The proposed approach is an attempt to make seamless integration of computer aided design with computer aided manufacturing. The features used in this study are taken from MusumiTM Catalogue as well as from various small and medium scale sheet metal industries. Work is divided into two phases. In the first phase, the relevant geometrical and topological data is extracted by reading STEP AP 203. In the second phase, a combine adjacency matrix and rule-based system is developed to recognize sheet metal features for die manufacturing. The system showed excellent performance for all types of features contained in the MusumiTM catalog and for different sheet metal industries. The proposed system for automated design of combination dies for sheet metal parts has been tested successfully for various types of industrial deep drawn parts. It reduces the die compoment design time from hours to minutes. selection of die components and drawings generated by the system were found to be reasonable and very similar to those actually used in the sheet metal industries for production of these typical components on combination dies.

Fatigue Behavior of Laser-Cut Sheet Metal Parts with Brazed-on Elements

Laser cutting is used in the production of formed sheet metal components. However, the cyclic load capacity is reduced compared to other subtractive processes. Laser cutting results in a significant loss of fatigue strength; however, thermal joining has its own effect on the cyclic load capacity. Accordingly, brazing causes a significant reduction in the mechanical strength. However, the open question is what consequences a combination of both processes may have on the overall fatigue strength of sheet metals. Laser-cut samples of AISI 304 with and without a brazed-on element were investigated for their microstructure and mechanical properties. The brazing process was found to have an annealing effect on the microstructure. It was further observed that the fatigue behavior of brazed specimens is dominated by inhomogeneities at the surface of the filler metal fillet located in the geometric notch of the brazed joint. Fatigue strength decreased by almost 50% compared to as-cut specimens. As long as no shared diffusion zone is formed between the laser-cut and the brazed joint, the use of laser cutting for the production of such components appears to be reasonable and does not further contribute to the loss of cyclic strength.

Effect of steel forming on vehicle side impact behavior

Despite the seemingly daily development of high-strength new generation steel sheets, steel sheets still remain the most important engineering material used in a vehicle body. These steel parts in a vehicle body, meant to absorb energy during impact, are generally produced by steel forming methods. These steel forming operations may contain processes such as deep drawing, bending, cutting, spring back, spinning. According to the production conditions and type of processes used during the production of sheet metal parts, thinning, thickening, plastic deformation, folding, tearing and wrinkling may occur. In order to achieve more reliable impact simulations, these effects in the forming process should be conferred on impact analysis. Within the scope of this study, an analysis of the critical parts in steel forming that absorb the most energy during the side impact was conducted – first for vehicles. In a subsequent impact analysis, the effects of changes (thickness distribution, residual stress, plastic deformation, etc.) during steel forming were examined.

A novel method for approximating local changes in the surface absorption for laser marking using 3D laser scanning

Laser marking is a non-contact technique, which achieves colouring by using a laser beam to increase surface oxidation. Controlling the amount of heat induced into the part is essential in ensuring the desired degree of oxidisation. However, the induced heat is not only dependent on the process parameters, but also on the surface absorption, which in turn is dependent on the material, laser wavelength, and surface quality, i.e., current degree of oxidation and contaminants as well as surface roughness. This paper proposes a method for correlating backscatter from a 3D laser scanner with the surface absorption of sheet metal parts. The purpose is to determine local changes in the surface absorption caused by surface oxidation and contamination. The method utilises a 3D laser scanner, which projects a laser line at the surface and measures the resulting backscatter at an angle. The proposed solution applies a bi-directional reflectance model to reduce the influence of varying scanning angles. The method’s sensitivity to variations in surface treatments is investigated and validated against backscatter spectroscopy measurements. The results show that the proposed method can identify changes in the absorption. However, these were, in some cases, more than 70% higher compared to spectroscopy measurements.

Impact of the electromagnetic field pressure on the bending of high convex-side

A large number of aircraft parts made of sheet materials are used as flanges, common to such parts is the presence of walls, sides, and various elements that increase rigidity and reduce mass. These sheet parts are complex, mostly closed forms, which by plastic deformation methods require a rather complex stamping tools. Technological methods of manufacturing have certain disadvantages associated with the need to refine the shaping. In addition, the frequent updating of product designs and their constant improvement with a significant amount of experimental and small-scale production required the creation of technological methods that provide a significant reduction in terms of preparation. When punching sheet metal parts, in particular, by the pressure of magnetic-pulse field, the accuracy of shaping is mainly influenced by the shape of the flange in the process of deformation. At the final stage of shaping, an impact contact occurs between the flange of the part with the die or form-block. On impact, elastic unloading of the flange occurs due to the removal of inertial tensile stresses along the generatrix. After the impact contact, dynamic springing or rebound of the flange occurs.