Showing papers by "Taylan Altan published in 2013"
TL;DR: In this paper, the effect of part geometry is considered to select the "best" clearance to minimize tool wear, and a method is developed to select a geometry dependent variable punch-die clearance to obtain more uniform wear on the punch, thereby increasing the punch and die life.
Abstract: Punch-die clearance is a well-known parameter affecting both tool life and edge quality of parts in blanking and piercing. Selecting the optimum or best punch-die clearance can give a significantly longer tool life by minimizing tool wear. Previous studies have shown the effect of punch-die clearance on various sheet materials and thicknesses during blanking of round parts while non-round geometries are more commonly found in industrial applications. Therefore, in this study, the effect of part geometry is considered to select the ‘best’ punch-die clearance to minimize tool wear. In blanking non-round geometries, the punch and die undergo non-uniform wear, with higher wear observed in areas with sharp radii and abrupt changes in geometry. In the present study, the effect of punch-die clearance on punch stress for blanking various shapes is investigated using Finite Element (FE) analysis. The punch-die clearance that gives the lowest value of the punch stress for the different part geometries is identified. A method is developed to select a geometry dependent variable punch-die clearance to obtain more uniform wear on the punch, thereby increasing the punch and die life.
51 citations
TL;DR: In this paper, an experimental study of the interaction between punch, stripper plate and sheet material at various blanking velocities up to 1600mm/s was conducted, and the effect of velocity on punching force was studied.
33 citations
01 Jan 2013
TL;DR: In this article, experiments and Finite Element (FE) simulations were used to investigate the hot stamping process for forming B-pillars from uniform thickness blanks and (b) tailor-rolled blanks with 2 different thicknesses.
Abstract: B-pillars are the key automotive components for side impact safety. The pillar must be strong enough to resist deformation during impact which can be achieved by using thick gage or high strength materials. Ultra high strength in formed sheet metal parts can reduce the weight of the vehicle and be achieved by hot stamping. However, low elongation in the hot stamping part reduces its energy absorption characteristics. To improve the crash performance and save weight, it is necessary to hot stamp components with tailored properties, i.e. variable strength and hardness throughout the part. For this purpose various techniques are used with blanks that are (a) tailoredtempered, (b) tailor welded with uniform or non-uniform thickness, and (c) tailored rolled. The use of tailored-rolled blanks, with variable blank thickness, is a relatively new application in hot stamping for saving weight and obtaining desired local stiffness and crash performance. As shown in the experimental part of this work, tailored-rolled blanks may also cause variation in the final temperature and microstructure of a hot stamped part. In this study, experiments and Finite Element (FE) simulations were used to investigate the hot stamping process for forming B-Pillars from (a) uniform thickness blanks and (b) tailor-rolled blanks with 2 different thicknesses. Simulations were conducted using LS-DYNA. The predicted temperature distributions are compared with data obtained from hot stamping tests. The experiments put forward the thickness transition of tailor-rolled blanks as one critical zone regarding final temperature and hardness. Preliminary simulation results cannot replicate this effect, suggesting that a refined approach is required to capture the experimental observations.
10 citations
31 Dec 2013
TL;DR: In this article, the authors discuss the recent improvements in modeling distortion and die design with cooling channels, together with a number of techniques to predict the final properties of a tailored part.
Abstract: Hot stamped components have been widely used in the automotive industry in the last decade where ultra high strength is required. These parts, however, may not provide sufficient toughness to absorb crash energy. Therefore, these components are “tailored” by controlling the microstructure at various locations. Simulation of tailored hot stamped components requires more detailed analysis of microstructural changes. Furthermore, since the part is not uniformly quenched, severe distortion can be observed. CPF, together with ESI have developed a number of techniques to predict the final properties of a tailored part. This paper discusses the recent improvements in modeling distortion and die design with cooling channels.
5 citations
01 Jan 2013
TL;DR: In this paper, the authors present tools for virtual prototyping of lightweight constructions designed and assembled with tailored solutions, specifically hot forming, which is a significant part of the hot forming process.
Abstract: Tailored solutions are one key to the lightweight construction challenges of the future. Only tailored solutions allow the combination of soft and hard zones for the best possible crash performance and minimum weight. The safety cage of future vehicles may completely be designed with hot formed components. In order to achieve the desired properties of the component, a heat treatment operation is necessary, and it comprises a significant part of the hot forming process. This poses additional challenges to the automotive industry as the heat treatment process is a function of many parameters and depends strongly on the forming process. In addition, only perfectly heat-treated parts will fulfill specifications. Virtual Prototyping makes sure that component manufacturing and assembly processes yield the designed tolerances and crash performance. ESI GROUP aims at providing all necessary tools for virtual prototyping of lightweight constructions designed and assembled with tailored solutions, specifically hot forming. This paper outlines what is needed for realistic virtual prototyping, and the status of the simulation solution. Validated realistic engineering examples are used to illustrate the capabilities in the field of virtual die design, forming, quenching, cooling channel engineering, assembly, and product performance.
1 citations
12 Jul 2013
TL;DR: Tailored cold and hot formed solutions are the key to the lightweight construction of the future vehicles as the combination of soft and hard zones for the best possible crash performance and minimum weight.
Abstract: Tailored cold and hot formed solutions are the key to the lightweight construction of the future vehicles. Only tailored solutions allow the combination of soft and hard zones for the best possible crash performance and minimum weight. The safety cage of future vehicles may completely be designed with hot formed components. In order to achieve the desired properties of the component, a heat treatment operation is necessary, and it comprises a significant part of the hot forming process. This poses additional challenges to the automotive industry as the heat treatment process is a function of many parameters and depends strongly on the forming process. In addition, only perfectly heat-treated parts will fulfill specifications.