Study Of Wrinkling Defects In Bending Thin-walled Micro-heat Pipes

Thin-wall sintered micro heat pipes (TSMHPs) have been the ideal components formicroelectronic and optoelectronic chips dissipating heat because of their excellent heattransfer performance. With the development of smaller space for microelectronic andoptoelectronic chips, the spatial geometry diversification of TSMHPs is being required toincreasingly improve. The bending of TSMHPs is the inevitable choice to achieve spatialgeometry diversification of TSMHPs, and the bending process of TSMHPs is mainly a rotarydraw bending process. Wrinkling defects restrict the development of the rotary draw bendingprocess of the TSMHPs. In this paper, the existing rotary draw bending process is greatlybeing improved, a new type of pure rolling rotary draw bending process has been proposed.On the basis of this new bending process, theoretical analysis, finite element method (FEM)and experimental research methods are to be used to study the optimization of wrinklingdefects. A brief introduction to the project and its main results are as follows:(1) The proposition and realization of a new pure rolling rotary draw bending process:Firstly, several common rotary draw bending process are introduced. Secondly, according tothe manufacturing process characteristics of the TSMHPs, Manual rotary draw bendingprocess without mandrels was selected as the bending process for TSMHPs. According to therotary draw bending process of the TSMHPs, a new rotary draw bending process in which therotary draw bending mold is rolling around the center mold is proposed. Thirdly, themechanical and kinematics characteristics of the process were analyzed, and the superiority ofpure rolling rotary draw bending process was proved. Eventually, this paper selecteddistortion of TSMHPs as the optimization objective function to optimize the structure of thepure rolling rotary bender, reasonable parameters of die sizes and the positional parametersbetween the molds were determined.(2) Optimized the wrinkling defects in the pipe bending by using the FEM: Taking intoaccount of the nonlinear characteristics of the deformation of TSMHPs in the bending process,the pure rolling rotary draw bending process of TSMHPs was optimized, in which the FEMwas used to reduce wrinkling defects in the bending process of TSMHPs. Firstly, this paperdescribed the basic theory of the FEM and its solution procedure. Secondly, according to the requirements of FEM software MSC.marc, a finite element model to analyze the stress-straincharacteristics and compression deformation zone characteristics in the bending of theTSMHPs was established. Thirdly, an orthogonal test, which was based on the finite elementmodels, was established, in which the wrinkling sizes were selected as the objective function.According to the results of orthogonal test, the optimization of wrinkling defects, which wasbased on the FEM, was proposed.(3) Optimized the wrinkling defects in the pipe bending by using the experiment method.In order to validate correctness of the FEM conclusions and to study the optimization ofwrinkling defects fatherly, test methods to study the effects of each key parameter forwrinkling was used. Combined with the actual production, eventually, the optimization ofwrinkling defects in the bending process of TSMHPs, which was based on FEM andexperiments, was established.