Zerteilen von Feinblechen durch Impulsmagnetfelder
Final Report Abstract
The possibility for the cutting of rectangular geometry by use of the pulsed magnetic cutting based on flat coil concept is principally proved. The main problem is the life time of the coil tool. The experiments performed in the first two research years have shown that the flat coils are not in a position to withstand high process forces between coil tool and work piece. The generated attractive and repulsive forces in the flat coil were critical. The second problem by use of the flat coil concept is regarded to the concentration of magnetic fields on desired positions on the surface of sheet metal. Due to this the adaptation of the cutting tool on different cutting operations seems to be impossible. For the enhancement of magnetic field shaping by developing new coil forms the existent manufacturing method can not introduce new solutions. Hence, the application of pulsed magnetic cutting based on flat coil concept for the manufacturing in large-volume production is not suitable. This disadvantage can be clearly detected by cutting a rectangular geometry. The investigations of the first two years have shown that by use of the pulsed magnetic cutting based on flat coil concept achieving a cut quality like conventional shearing methods can not be feasible. Due to above mentioned restrictions design and development of new tool system for the removing of these deficits is necessary. As a new tool concept a combination of compression coil with a field concentrator was developed. The field concentrator can be in a position to respective influence of magnetic fields and their focussing on desired areas. Another advantage of this component is related to its better resistance against process forces. For this purpose different field concentrator geometries were designed and developed. This includes the analysis of influences of geometries like clearances, bores as well as slots on the shaping of magnetic field lines. By the first concept based on using a square opening a great dispersion of the magnetic field on the outside of the cutting edge was observed but it showed a good ability for the production of high magnetic pressure. For the investigation of the influence of bores and slots a second concept was developed. It showed a better potential for the influence of field lines but the achievable magnetic pressure was not as high as the first concept. For the better analysis of different geometries by a third concept other dimensional changes instead of circular small bores from rectangular bores have been used. Hereby, the results were regarding to generated magnetic pressure respectively better than the second concept and the cutting of work piece in two sides under a discharge energy of 5 kJ could be realized. The use of copper alloy with the type of Cu-ETP in the first three concepts due to the plastic deformation of these components showed a necessity for the substitution of this copper alloy. Because of this the other field concentrators are made from zirconium copper alloy with comparable electrical conductivity and better mechanical properties. The state of these components before and after application by the second three field concentrators proves the suitability of this alloy for this application. The operation of several experiments after using the fourth and fifth concepts with different constructive changes showed that the optimal results under a combination of square opening with reduced dimensions can be achieved. For this purpose the last concept on this base was designed and developed. At a discharge energy of 5 kJ the cutting of sheet metal in all sides could be realized. The enhancement of cut quality in the corners by use of this concept was proven. For the better evaluation of cut quality polished specimens have been analyzed metallographic. This was compared with the results of conventional shearing method as well as flat coil concept. It is detectable that the heeling depth and -height by use of the field concentrator concept is comparable with the cut quality under use of the flat coil concept and higher than by conventional shearing method. The only different is related to a difference in fracture angle, which for field concentrator concept is less than achieved result by flat coil concept. The obtained results with the finite element method regarding the number of change loads under this the cutting operation can be performed shows high potentials of this concept for the manufacturing in largevolume production.
Publications
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Investigation about the Influence of Different Field Concentrator Concepts on the Cutting Quality by the Pulsed Magnetic Cutting of Al-Sheet Metals, Workshop Elektromagnetische Umformung, Dortmund, 23/03/2007, pp. 72-79.
K. Damavandi; E. Uhlmann
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New Developments in Tool Design for the Pulsed Magnetic Cutting of Aluminum Sheet Metal, accepted for the presentation in 2nd International Conference on New Forming Technology, 20th- 21st September 2007, Bremen, Germany
K. Damavandi; E. Uhlmann; N. Bayat
