Study On Neck-shrinkage Mechanism Of Micro Thin-wall Inner Grooved Tube

With the rapid rising of heat flux and the reduction of dissipating space in the microelectronic and optoelectronic field, micro-grooved heat pipe has become an ideal conducting element for its highlight advantages of high heat conductivity, high reliability, fast thermal response, and no extra electric power.The airtightness is extremely important for micro-grooved heat pipe since its heat conducting process is undergone in an enclosure space. At present, micro thin-wall inner grooved tube, as the tube blank of micro-grooved heat pipe, is sealed by neck-shrinkage and welding. This paper focus on the neck-shrinkage process of micro inner grooved tube and the neck-shrinkage mechanism is researched with the aid of finite element simulation and experiments. After that, a neck-shrinkage machine which meets the requirement is developed.Fistly, base on the structure fectures of grooved tube and the neck-shrinkage requirements, stempressing, spinning and forging, wich are widly used to reduce tube caliber, are analyzed and ball spinning and radial forging are chosed as the fabrication method. Sencondly, with the help of finite element sofeware MSC.Marc, the three-dimensional elastic-plasticity finite element models of ball spinning and radial forging are extablished and the neck-shrinkage processes are simulated. The forming characteristics, metal flow, distribution of equivalent stress and strain and load cases are analyzed. Thirdly, the neck-shrinkage experiments via ball spinning and radial forging are carried out to confirm the forming characteristics of the neck-shrinkage process and effects of related processing parameters. The experiment results agree well with the simulation results. Finally, base on the analysis of the advances and disadvances of ball spinning and radial forging, the radial forging is decided as the ideal fabrication method for grooved tube neck-shrinkage. The radial forging machine is designed.