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The Formation Of Preform For Regular Slender Straight-through Hole And The Hole Forming Process

Posted on:2016-09-11Degree:MasterType:Thesis
Country:ChinaCandidate:F S SunFull Text:PDF
GTID:2181330467990143Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
This research mainly focuses on controllable slender straight-through hole with castingmethod. Based on poor wettability between carbon and metal, the aluminum liquid can aroundthe hole cores to be holes after it was solidification and the hole cores were pulled out. Incontrast to conventional hole forming methods such as mechanical or special process, theproposed method did not require any additional sophisticated equipment and acquired slenderstraight-through hole with super large aspect ratio by casting.Firstly, the experiment was constituted and the carbon fiber perform and steel needleperform were designed, the structure of the preforms were improved during the process ofexperiment. Secondly, the aluminum was chosen to be base material and the two kinds ofpreforms were adopted for experiment, the controllable straight-through array micro holeswere successfully fabricated by using preform. The result shows that: the distribution of theholes fabricated by the two kinds of preform are very regular and dense; the average diameterand the depth of the holes fabricated by using carbon fiber preform is0.216mm and64.3mm,the aspect ratio is up to297; the average diameter and the depth of the holes fabricated byusing steel needle preform is0.518mm and99.4mm, the aspect ratio is up to192, the shapefactors of the holes vary between0.853and0.929,the shape of the holes is very close to circle;the roughness of hole wall is3.84, it reaches the scope of hole wall roughness fabricated byordinary mechanical processing. Thirdly, the hole depth model was established by study theresistance of hole forming to analyse the effect of adjacent hole cores distance on hole depth.According to the hole depth model, it can be known that: the depth of array micro holes arerelated to the distance of adjacent hole cores in theory, with the distance decreasing, the holedepth will increase. Finally, several specimens were made to measure the values of holediameter and depth, and the correctness of the hole depth model in this paper is verified bycompare the depth measured value and theory value.The absolute error and the relative errorof the theoretical values and measured values in this experiment is6.2mm and6.21%.
Keywords/Search Tags:Hole cores, Preform, Straight-through array micro holes, Large aspect ratio, Casting method
PDF Full Text Request
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