A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Development of ultra high performance concrete dies for sheet metal hydroforming
The paper reports investigation results on UHPC dies (ultra high performance concrete) for the use in sheet metal hydroforming. A special mixture of UHPC for the tools is presented showing its mechanical properties and its manufacturing. The developed UHPC was investigated by multi-axial compression tests. After one-day humid heat curing subsequent to moulding, the UHPC already features a compressive strength of appr. 250 MPa and a Young's modulus of 50 GPa while having approximately a third of the weight of comparable steel. Under internal pressure, the UHPC die fails in an expected pressure range between 80 and 96 MPa and in expected crack directions. In view of industrial forming processes, the strength and the stiffness of the UHPC die provide the opportunity to form a wide range of different low and medium contoured part shapes. However, in case of small part radii, the UHPC die cannot withstand the required internal pressure. The test with a steel tube confined UHPC core showed the potential of confinement or reinforcement techniques in face of higher internal pressure. The forming test proved a good shape accuracy of the sheet metal parts. Shape deviations of the UHPC die due to shrinkage are negligible. The tribological conditions between UHPC and sheet without coating or interlayer are undefined and up to now, unsuitable for sheet metal forming. Drawing foil and already formed sheet metal parts were tested successfully as interlayer and led to an appropriate material flow and surface quality of the sheet metal parts. Further improvement will be aspired by using alternative casting core materials with less porosity of the surface, coatings, and novel confinement or reinforcement techniques.
Development of ultra high performance concrete dies for sheet metal hydroforming
The paper reports investigation results on UHPC dies (ultra high performance concrete) for the use in sheet metal hydroforming. A special mixture of UHPC for the tools is presented showing its mechanical properties and its manufacturing. The developed UHPC was investigated by multi-axial compression tests. After one-day humid heat curing subsequent to moulding, the UHPC already features a compressive strength of appr. 250 MPa and a Young's modulus of 50 GPa while having approximately a third of the weight of comparable steel. Under internal pressure, the UHPC die fails in an expected pressure range between 80 and 96 MPa and in expected crack directions. In view of industrial forming processes, the strength and the stiffness of the UHPC die provide the opportunity to form a wide range of different low and medium contoured part shapes. However, in case of small part radii, the UHPC die cannot withstand the required internal pressure. The test with a steel tube confined UHPC core showed the potential of confinement or reinforcement techniques in face of higher internal pressure. The forming test proved a good shape accuracy of the sheet metal parts. Shape deviations of the UHPC die due to shrinkage are negligible. The tribological conditions between UHPC and sheet without coating or interlayer are undefined and up to now, unsuitable for sheet metal forming. Drawing foil and already formed sheet metal parts were tested successfully as interlayer and led to an appropriate material flow and surface quality of the sheet metal parts. Further improvement will be aspired by using alternative casting core materials with less porosity of the surface, coatings, and novel confinement or reinforcement techniques.
Development of ultra high performance concrete dies for sheet metal hydroforming
Kleiner, Matthias (author) / Curbach, Manfred (author) / Tekkaya, A. Erman (author) / Ritter, Robert (author) / Speck, Kerstin (author) / Trompeter, Michael (author)
2008
8 Seiten, 13 Bilder, 1 Tabelle, 18 Quellen
Article (Journal)
English
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