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Technical Paper

Warm Forming of Magnesium Sheet Metal

2004-03-08
2004-01-1043
This paper deals with warm forming of Magnesium AZ 31 sheet metals. Experimental investigations on the formability of AZ31 at temperatures up 350°C have been carried out. The following the results of these investigations, such as stress-strain curves, forming limit curves are presented. For hydromechanical deep drawing, the influence of the tool- and fluid temperature on the achievable maximal drawing ratio and on the maximal achievable strains in the bottom of the component is shown.
Technical Paper

Die Concepts for Hydromechanical Deep Drawing

2004-03-08
2004-01-0828
Deep drawing with hydraulic counter pressure has numerous advantages compared to conventional deep drawing. Hydromechanical deep drawing is a capable process for producing complex and tapered-shaped stamping parts as well as parts with excellent surface quality, i.e., outer body panels. Due to the low costs of dies, compared to the conventional deep drawing dies, hydromechanical deep drawing has to be considered especially for low volume production. This paper deals with press- and die concepts for hydromechanical deep drawing. The die concepts can be equipped with an integrated multi-point cushion system. It is also possible to build a press with a multipoint cushion system integrated into the press. In this case, the die is less expensive but the press is more complex. The counter pressure pot can be product specific as a part of the die or as a part of the press investment.
Technical Paper

Forming of Tailored Blanks with Non Linear Weld-Lines

2000-03-06
2000-01-0414
This paper deals with the design of draw dies for nonlinearly welded tailored blanks. It is pointed out that design of draw dies for tailored blanks should be the result of computer aided design of the die and FEM-simulation of the deep-drawing process. Principle problems of deep-drawing tailored blanks are discussed. Finally a segmented blankholder system is introduced.
Technical Paper

Forming Behavior of Isotropic Steel Sheets

2000-03-06
2000-01-0413
The demand of automotive industries to reduce the fuel consumption and therefore the weight in vehicle construction are becoming more and more significant. The reduction of the weight in vehicle construction can be realized among other factors with lighter car bodies. Particularly the reduction of the sheet metal thickness in car bodies can provide a significant contribution to solve this problem. In this case the use of high-strength steel is necessary. Isotropic high-strength steels, so-called I-Steels (e.g. St250i) have been developed by the steel supplier SALZGITTER AG-Germany. These high-strength I-Steel sheets show direction-independent (“isotropic”) material qualities and a very good deep drawing behavior. With these I-Steels, interior components as well as outdoor panels can be produced.
Technical Paper

New Machine Concept for Hydroforming Tubes and Extrusions, Part 2

1999-09-28
1999-01-3158
In cooperation with industrial companies at the Institute for Metal Forming Technology (IFU) of the University of Stuttgart, Germany, a new press concept specially for hydroforming tubes and extrusions was developed. The press has a capacity of 3500 tons closing force and a press table size of 2500 mm × 900 mm. A great reduction in costs can be achieved by integrating spacers between the frame of the press and the ram. This paper introduces this new press.
Technical Paper

New Machine Concept for Hydroforming Tubes and Extrusions, Part 1

1999-03-01
1999-01-0678
By inner pressure hydroforming a great variety of parts can be produced. This is especially true when forming tubes in a single action press with high closing forces. In cooperation with industrial companies at the Institute for Metal Forming Technology of the University of Stuttgart, Germany, a new concept for presses specially designed for hydroforming tubes and extrusions was developed. The press has a capacity of a 3500 tons closing force and a press table size of 2500 mm × 900 mm. A great reduction in costs can be achieved by integrating spacers between the frame of the press and the ram. This paper introduces this new press and discusses different press concepts for hydroforming tubes and extrusions.
Technical Paper

Development of a Portable Sensor for the Three-Dimensional Measurement of Sheet and Tool Surfaces

1999-03-01
1999-01-0684
In deep drawing and drawing of car-body parts the friction conditions have a great influence on process limits, on the robustness of the production process and on the quality of the produced parts. Beside the used lubricant, the friction conditions are influenced by the topography of the sheet metal surface and of the tool surface. Therefore the roughness of these surfaces has to be measured. It is well established to measure the roughness of sheet metal surfaces with a stylus device. But more and more optical measurement techniques are upcomming. There are for example instruments on the market which can characterize the roughness profile along a line with an infra-red laser beam. Doing this for parallel lines the topography can be plotted in three dimensions. The disadvantage of all those systems is that the samples to be measured have to be cut from the sheet or from the coil and that is not possible to measure directly the surface of heavy forming tools.
Technical Paper

Optimized Radii for Draw Dies

1999-03-01
1999-01-0685
This paper deals with the radii of draw dies for sheet metal parts, like fenders, hoods, and doors. For relative flat parts, like hoods, it is important to get at least a 2% forming rate in the middle of the part to reach minimum of stiffness, work hardening, and sufficient geometric accuracy. This can be influenced by the punch radii. Therefore, optimal punch radii should be known. First experimental results about optimal punch radii where published by J.L. Duncan and B.S. Shabel in the SAE-Paper No. 780391. At the Institute for Metal Forming Technology of the University of Stuttgart, Germany, a “Modified Duncan Shabel Test” (MDS-Test) has been developed. This test makes it possible to investigate not only the punch radii but also the die radii. This paper shows optimal punch and die radii as a function of sheet metal, sheet thickness, as well as of the die material.
Technical Paper

Combination of Hydraulic Multipoint Cushion System and Segment-Elastic Blankholders

1998-02-01
980077
The costs for development and production of draw dies for car outer panels are extremely high and should be reduced. Furthermore it is necessary to reduce the time for developing, designing and producing the dies for the production of parts. This paper discusses new press techniques, die designs and an adjustment program for press operators. The trend goes to single action presses with CNC-controlled multipoint cushion systems in the press table and to special designed dies. These systems lead to a more robust and reproducible forming process with improved product quality. This paper deals with: Cushion Systems, New Binder Designs for Draw Dies for Sheet Metal Automotive Parts, New Computer Program to Adjust the Blankholder Forces of Modern Hydraulic Cushion Systems of Single Action Presses and Pressure Measurement for Detecting the Pressure between the Blank and the Binders of Draw Dies for Sheet Metal Automotive Parts.
Technical Paper

Binder Design for Automotive Body Panels

1996-02-01
960822
The objective of this paper is to introduce a method for producing effective binder designs for sheet metal forming of automotive body panels. The fundamentals steps of die design are discussed as well as methods for checking the developability of binder surfaces and the application of a binder simulator and FEM process simulation. A front fender and a door panel have been used to illustrate the methodology.
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