Tool System for Ultrasonic-Assisted Forming and Material Characterisation with 15 kHz Oscillation Frequency

It is well-known that superimposed ultrasonic tool vibrations are capable of decreasing the forming force and the interfacial friction during the deformation of metal. The complex causes of this phenomenon were mainly investigated by focusing on oscillation frequencies above 20 kHz. Due to limitations of the load capacity and the power of the oscillating systems, mostly soft materials, such as aluminium and copper, were analysed. The present study is concerned with the development of a tool system for ultrasonic-assisted compression tests with a 15 kHz oscillation system. The advantages of this type of oscillating system are an increased power and robustness, which allow the testing of high strength materials. In preliminary ultrasonic-assisted compression tests with a S235JR steel a force reduction of up to 63 % was measured. The major challenges identified during the preliminary investigations are a transversal drift of the specimen, a periodic separation between the die and the specimen, a high sound emission and a high demand on the measuring and signal processing technology. Based on the technical challenges and the determined requirements a tool system is introduced.