Zhixin Zeng

Production of long metal fibers using a combined method of microsaw turning and pulling

Abstract The performance of metal fibers, such as the roughness of their appearance, the length, the strength and the diameter are very important when they are used as filling and intensifying material of composites. How to control the performance of metal fibers in a simple and economical way when producing metal fibers has attracted attention for decades. In this paper, a new method which combines microcutting and pulling is put forward and has found application in producing long metal fibers. The main technical parameters which affect the characteristic of long metal fibers are discussed and the proper values to achieve good performance of the metal fibers are obtained with low carbon steel as the raw materials.

Analysis of collapse in flattening a micro-grooved heat pipe by lateral compression

The collapse of thin-walled micro-grooved heat pipes is a common phenomenon in the tube flattening process, which seriously influences the heat transfer performance and appearance of heat pipe. At present, there is no other better method to solve this problem. A new method by heating the heat pipe is proposed to eliminate the collapse during the flattening process. The effectiveness of the proposed method is investigated through a theoretical model, a finite element(FE) analysis, and experimental method. Firstly, A theoretical model based on a deformation model of six plastic hinges and the Antoine equation of the working fluid is established to analyze the collapse of thin walls at different temperatures. Then, the FE simulation and experiments of flattening process at different temperatures are carried out and compared with theoretical model. Finally, the FE model is followed to study the loads of the plates at different temperatures and heights of flattened heat pipes. The results of the theoretical model conform to those of the FE simulation and experiments in the flattened zone. The collapse occurs at room temperature. As the temperature increases, the collapse decreases and finally disappears at approximately 130 °C for various heights of flattened heat pipes. The loads of the moving plate increase as the temperature increases. Thus, the reasonable temperature for eliminating the collapse and reducing the load is approximately 130 °C. The advantage of the proposed method is that the collapse is reduced or eliminated by means of the thermal deformation characteristic of heat pipe itself instead of by external support. As a result, the heat transfer efficiency of heat pipe is raised.