Preform Design of Double End Flange Stud

• Main Authors: Cheng-Fu Lu, 呂正富
• Other Authors: Chao-Cheng Chang
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/3w6299

碩士 === 國立高雄應用科技大學 === 模具系碩士在職專班 === 103 === Double end flange studs have two threads with different dimensions. The billets for producing the studs required a multi-stepped rod with different diameters. In general, the billet for the double end flange stud can be produced by two processes, a two-stage forging process using a multi-stage horizontal forging press, and a machining process. To avoid the machining process and reduce the costs, it is widely interested to develop new methods for manufacturing the billet for threading studs. This study proposed a three-stage preform design for producing the billet for a double end flange stud. The billet had two step rods for threading M8 and M10 screws. The first stage was to form the end with the smaller diameter. The stage used a backward extrusion process in a close die to avoid the problem with a large reduction rate of section and the difficulty in rotating a long billet during the transferring in a press. The stage was the key to the preform design for producing the billet. The second stage used a forward extrusion to fabricate the end with the larger diameter. The third stage employed an upsetting process to increase the diameter of the middle part of the workpiece and form the flange of the billet. The study considered the Cr-Mo steel (JIS SCM 435) for stud and used the simple upsetting to obtain the stress and strain curve for the simulations of the forming process using a finite element package, DEFORM. The proposed preforms were further used in the die design and die manufacturing. Finally, the experiments of extrusion and upsetting were conducted and the results were analyzed. The results showed that the predicted loads were close to the experimental ones and the predicted the patterns of the metal flow were also in good agreement with those in the produced products. The proposed preform design can be used to successfully manufacturing the billet for threading the double end flange stud. The results not only could be the base of the preform design for producing screw billets in fastener industries but also could be the references for other metal forming industries.