The effect of an electromagnetic peening process on mumetal properties
Peening processes are widely used in the industries to enhance the performance of the most solicited parts of mechanical pieces. Actual processes, like shot peening and low plasticity burnishing, are quite limited to a small depth of treatment circa 1 mm at maximum. A new process is developed based on pulsed electromagnetic fields. This method allows a better depth of treatment up to 5 mm and it can be easily monitored. A prototype was developed using a pulse current generator and specifically designed inductor. This prototype was used on mumetal for the preliminary tests. Indeed, its maximal permeability and coercivity are highly impacted by the presence of stresses. Using specifics sensors, some changes occur after treatment on mumetal samples and can be observed.
Design of a high current pulse generator for magnetoforming
Magneto forming of tube or sheet metal parts can significantly extend the range of geometries conceivable with state-of-the-art forming methods. Major advantage is the considerably higher forming speed of the process achievable by using a magnetic piston without inertia. Key for this technology is the development of reliable, long-lifetime, high current pulse power generators able to deliver tens to hundreds of kiloamps of peak current to a mainly inductive load which is highly variable in time during the forming process. We report on the design of a pulse generator for peak currents of up to 200 kA at a pulse width of typically 80 mus, depending on the load parameters. In order to meet lifetime requirements suitable for industrial applications, the short circuit handling capability of peak currents of up to 450 kA is a major issue in the pulse generator design. A modular, 3-branch design has been adopted to achieve the requirements concerning reliability, lifetime, and short circuit handling. The prototype design is based upon off-the-shelf devices, including high-current discharge switches based on semiconductor devices. The basic concept of the pulse generator is presented, including results from extensive circuit modeling concerning nominal performance as well as short circuit behavior
SEMICONDUCTOR SWITCHES FOR SINGLE PULSE AND REPETITIVE PULSE APPLICATIONS
An overview is given about solid state pulse power switches which are designed for single pulse applications i.e. launch systems (ET or EM Guns) and active armour. Also a newly developed switching system is presented which can be used for repetition frequencies up to 400 Hz, high di/dt, up to 20 kVdc and pulse currents of over 15 kA, designed for laser applications. (Solid State alternative for Thyratrons) By using a modular platform technology, a variation of four standardized silicon wafer sizes can be selected to reach the required current and di/dt levels, and by stacking devices in series connection, voltages of up to 50 kV can be realized. The presented switches and components are including the triggering system, and where required, also including power supply and heatsinks.