The Research and Development of Heating Raw Material Within Forming Die for Screw Head.

• Main Authors: Yu-Shun Zheng, 鄭宇順
• Other Authors: Fang-Sung Cheng
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/34k8rz

碩士 === 國立虎尾科技大學 === 機械與電腦輔助工程系碩士班 === 101 === How to develop special alloy fastener products with high price value for better profitability is the top priority that faces Taiwan''s metal forging industry, especially the manufacturers of screws. To face the tougher press forging of special metals, there are the following hot forging press: (1) heating and then forging billets inside the furnace; (2) heating by electromagnetic coil induction, and (3) heating by electric heating rod die. These approaches, however, require forging after heating, and the consequent partial temperature drop can change the material stress. Meanwhile, a direct resistive heating to forge billets inside the mold not only reduces the uneven distribution of material temperature, surface oxidation and surface material coarsening, but also alleviates the stress hike resulted from the material temperature drop during the forging process, thus greatly improves the malleability and mass production capacity of nickel-base superalloy materials. Also, the nickel material is a key factor to the forging process and simulation parameters. In view of this, this research proposes a forging approach that directly heats billets inside a mold. The study comes in four parts: (1) simulation of the bolt head forging process; (2) experiment of the direct resistive heating inside a mold; (3) experiment of the resistive heating inside the mold to forge the bolt head; and (4) experiment of the nickel alloy resistive heating inside the mold to forge the bolt head. The software tools DEFORM-3D and DEFORM-2D are used to simulate the bolt head heating and forging patterns and, based on the simulation results, real molds are built to test the resistive heating inside the molds, followed by tests of resistive heating and forging of bolt heads inside the molds, and finally nickel-based alloy materials are taken for experiment and discussion of the resistive heating and forging of bolt heads. The experiment results show that (1) the direct resistive heating and forging of billets inside the mold is feasible, and using a preload device can correct the poor heating; (2) this research has successfully heated the SCM440 billet, swiftly and directly, up to 1100℃ for the bolt head forging process, thus proposed a gradual heating pattern to improve the filling of the bolt head forging; (3) when this approach is applied to 718 and C276 nickel alloys, the heating pattern is different from that with SCM440, causing the overall temperature of the billet unable to reach the forging temperature or causing the billet''s partial temperature over the melting point, resulting in failed forging.