Papers by Author: F. Liu

Abstract: To solve the difficult problem of selecting processing parameters of plasma arc cutting ceramic (PACC), the heat conduction model of PACC has been established and the calculating formulations of temperature field have been derived. Then, the distributions and influence factors, such as arc power, cutting speed and workpiece thickness, of temperature field of the ceramic plate and the anode plate have been studied. Based on the work above, the required arc power can be calculated. Moreover, the relation between thickness of ceramic plate and anode plate can be determined, which provides a helpful reference for selecting the thickness of additional anode plate.

Abstract: Flexible forming using plasma arc (FFUPA) is a newly developed method of sheet metal forming. It makes the forming by means of thermal stress and thermal strain without mould and die, and is recognized as a promising forming method in developing new products. But the forming effect of FFUPA is determined by many factors, which compose a highly nonlinear system due to their complicated interact. As a result, it is difficult to predict the forming results and choose the processing parameters in FFUPA. In this paper, BP neural network is applied to solve this problem. After introducing the mechanism of FFUPA and analyzing the influence of processing parameters on the forming result, BP neural network is established, which include an input layer, an output layer and a hidden layer. When inputs and outputs are properly chosen, the BP neural network can be used to predict the forming results and to select the forming parameters. To verify the validity of this network, the results obtained by the BP neural network are compared to those obtained by experiments, and the results show that the former is close to the later, which indicates it is feasible to apply BP neural network in determining the processing parameters and forecasting the bending effects in FFUPA.

Abstract: For the development of flexible forming using plasma arc (FFUPA), it is extremely necessary to investigate the forming rules of curvilinear scanning and multipath combined scanning. In this paper, the difference between circular scanning and linear scanning and the influence of sheet metal geometry on forming effect have been discussed. In the experiments, circle, ring and rectangle mild steel sheets with thickness of 0.8mm are taken as workpieces and the experimental results show that nonlinear prolonged surface can be obtained by curvilinear scanning and there exists the obvious difference between circular scanning and linear scanning. Afterwards, the reason of the difference mentioned above is concisely analyzed. Finally, some suggestions are presented for the future investigation.