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  • 學位論文

異形活塞筒沖壓製程設計與分析

Design and Analysis of Stamping Process for a Cylindrical Part

指導教授 : 陳立緯
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摘要


引伸成形是金屬板材成形中最重要的技術之一,在引伸加工成形領域中,已經有許多對於引伸製程參數相關之研究,有限元素分析軟體對於引伸製程之模擬與預測亦可達到一定的可靠度,本研究應用有限元素分析軟體(PAM-STAMP),結合實際生產人員的現場試模經驗,針對圓筒形零件-異形活塞的沖壓製程進行成形分析,以改善實際生產過程中,板材經過多道次成形部分厚度變薄甚至出現破裂等缺陷,並配合田口實驗方法,對模具進行最佳化設計,以減少成品成形道次與需再進行車銑加工等製程,並探討引伸加工中壓料板壓料力及其負荷曲線,對於引伸加工成形之影響。 經研究結果顯示,應用引伸成形製程,須以七道次成形才可將異形活塞之圓筒外形加工成形,而引伸與引縮成形複合之製程,對於圓筒件之外形加工只需五道次成形,故應用引伸與引縮成形複合之製程將可減少圓筒件引伸之成形道次。其中板材與模具間之摩擦係數對低引伸比的成形厚度影響不大,而對於高引伸比之成形厚度將有顯著的差異。透過田口實驗方法對圓筒件引伸成形進行最佳化分析,可使成品最小厚度增加與最大厚度減小,且可降低引伸成形之成形負荷。在壓料板彈簧力部分,不同的壓料力負荷曲線,雖然其最大負荷相同,但在成形過程中,會使板材在同一沖壓行程時有不同的變化,因而使成形後之成品厚度有所差異。在沖剪與彎曲成形部分,外凸形式下料線經彎曲成形後,會使彎曲區域產生材料堆積,但可降低板材因彎曲成形所造成拉伸過度而破裂的情況產生,而內凹形式則反之,經彎曲件回彈分析,內凹0.3mm形式之回彈角為最小。 經實際量測與模擬分析結果比對後,其成品厚度最大誤差為9.69%,而最小誤差則為4.11%,故可驗證PAM-STAMP有限元素軟體應用於異形活塞之沖壓製程,其具有一定之可行性與可靠性,且有助於了解沖壓件的成形過程、應力、應變、成形極限與成形負荷等情況,能更有效的預測或預防成品缺陷的產生,以增進生產效益。

並列摘要


Many studies have been proposed in drawing process. The finite element method can achieve a certain reliability for the drawing process simulation and prediction. The research applied finite element analysis software (PAM-STAMP), along with manufacturer's experience, to analyze the stamping production process for cylindrical component, as well as improving some defect of cracks due to lessening in thickness from repetitive sheet molding. And, with taguchi method, die design was optimized to reduce number of repetitive molding and other machining processes. The effect of blankholder force and its load curve on the product formability would also be investigated. Result showed the application of drawing process would require 7 steps to finalize the forming of cylindrical component, while the combined machining process of drawing and ironing could reduce it to 5 steps. The friction coefficient of sheet and die had less impact on the thickness of product with low drawing ratio, but varied significantly for higher drawing ratio product. By taguchi method to optimize the drawing process, it could increase the minimum and reduce the maximum for the optimal product thickness to decrease the load. As for the blankholder spring force of different load curves, even though they might exhibit the same maximum loading force, the sheet under the same stamping process might still develop variation during the molding process, resulting in different product thickness. Part of stamping and bending, the convex forming process would result in accumulation of material at the bend, but could reduce chance of cracks due to excessive sheet drawing, while the concave forming process resulted in the opposite. The springback analysis showed that the concave forming process had the smallest springback angle. From the actual measurement and analysis comparison, the maximum error in product thickness was 9.69%, and the minimum was 4.11%. It proved the plausibility and reliability of using analytic software for the stamping procedure, and it could help to understand the forming process, stress, strain, forming limit and forming load of a forming stamped component, in order to effectively predict and even prevent defect formation, to further improve the productivity.

參考文獻


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