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Technical Paper

The Role of Second Phase Hard Particles on Hole Stretchability of Two AA6xxx Alloys

2017-03-28
2017-01-0307
The hole stretchability of two Aluminum Alloys (AA6111 and AA6022) are studied by using a two stages integrated finite element framework where the edge geometry and edge damages from the hole piercing processes were considered in the subsequent hole expansion processes. Experimentally it has been found that AA6022 has higher hole expansion ratios than those of AA6111. This observation has been nicely captured by finite element simulations. The main cause of differences have been identified to the volume fractions of the random distributed second phase hard particles which play a critical role in determining the fracture strains of the materials.
Technical Paper

Sheared Edge Stretchability of Steels Suitable for Automotive Applications

2017-03-28
2017-01-1708
In recent years, dual phase (DP) Advanced High Strength Steels (AHSS) and Ultra High Strength Steels (UHSS) are considered as prominent materials in the automotive industry due to superior structural performance and vehicle weight reduction capabilities. However, these materials are often sensitive to trimmed edge cracking if stretching along sheared edge occurs in such processes as stretch flanging. Another major issue in the trimming of UHSS is tool wear because of higher contact pressures at the interface between cutting tools and sheet metal blank caused by UHSS’s higher flow stresses and the presence of a hard martensitic phase in the microstructure. The objective of the current paper is to study the influence of trimming conditions and tool wear on quality and stretchability of trimmed edge of DP980 steel sheet. For this purpose, mechanically trimmed edges were characterized for DP980 steel and compared with other steels such as HSLA 350 and BH210.
Technical Paper

Effect of Tool Stiffness and Cutting Edge Condition on Quality and Stretchability of Sheared Edge of Aluminum Blanks

2016-04-05
2016-01-0348
Stamping die design recommendations attempt to limit the production of burrs through accurate alignment of the upper and lower trimming edges. For aluminum automotive exterior panels, this translates to a clearance less than 0.1 mm. However, quality of sheared edge and its stretchability are affected by stiffness of the cutting tool against opening of the clearance between the shearing edges. The objective of the study is to investigate the influence of stiffness of trimming or piercing dies against opening of the cutting clearance on sheared edge stretchability of aluminum blanks 6111-T4. For experimental study, one side of the sample had sheared surface obtained by the trimming process while the other side of the sample had a smooth surface achieved by metal finish. Burr heights of the sheared edge after different trimming configurations with 10% clearance were measured.
Journal Article

Analysis of Tool Wear for Trimming of DP980 Sheet Metal Blanks

2017-03-28
2017-01-0302
In recent years, implementation of dual phase (DP) Advanced High Strength Steels (AHSS) and Ultra High Strength Steels (UHSS) is increasing in automotive components due to their superior structural performance and vehicle weight reduction capabilities. However, these materials are often sensitive to trimmed edge cracking if stretching along sheared edge occurs in such processes as stretch flanging. Tool wear is another major issue in the trimming of UHSS because of higher contact pressures at the interface between cutting tools and sheet metal blank caused by UHSS’s higher flow stresses and the presence of a hard martensitic in the microstructure. The objective of the present paper is to discuss the methodology of analyzing die wear for trimming operations of UHSS components and illustrate it with some examples of tool wear analysis for trimming 1.5mm thick DP980 steel.
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