980級混合斷面基礎載具扭曲改善

Abstract

隨著日益嚴重的全球暖化與逐漸被重視的環保意識，以先進高強度鋼作為汽車結構件的材料已漸漸成為主流，其高強度可使使汽車結構件以較薄的厚度達到相同之強度，同時兼顧輕量化與安全性。但隨著鋼板強度提升，沖壓成形後之回彈缺陷亦更加明顯，常見之回彈缺陷有側壁外開、側壁捲曲與扭曲，其中扭曲為最複雜之回彈缺陷，本研究嘗試探討板金沖壓成形當中之扭曲回彈缺陷。 汽車結構件當中以A柱最容易產生扭曲之回彈缺陷，本研究歸納A柱之特徵造型參數，建立仿A柱之混合斷面基礎載具，以專業板金沖壓模擬軟體PAM-STAMP進行混合斷面基礎載具之成形模擬，模擬使用之材料為980級先進高強度鋼。首先針對不同造型參數進行成形性分析，探討各造型參數對於破裂與皺褶之影響，結果可以做為A柱造型設計之參考。接著模擬不同造型參數對扭曲影響，透過不同造型參數之混合斷面基礎載具成形後之板材應力分析，探討扭曲機制。透過常見之回彈改善策略如壓料力、阻料條與模面補償進行扭曲之改善，其中本研究找出扭曲之模面補償方式，解決扭曲之模面補償後無法沖壓的問題，同時改善扭曲之效果亦相當顯著，扭曲量由9度改善至1.5度。研究最後進行混合斷面基礎載具之模具設計。

As the global warming becomes worse and the environmental consciousness rises, AHSS has been widely used as the material of automobile structural parts. However, as the strength of steels increases, stamping defects such as sidewall curl and distortion become worse. This study investigates the distortion in sheet metal forming. A-pillar is an automobile structural part. Among all automobile structural parts, A-pillar is most likely to be distorted. This study induces the geometric parameters of A-pillar. This study also establishes a model for curved hat channel which has similar geometry with the A-pillar and uses PAM-STAMP to simulate the stamping process with the established model. This study investigates the formability influenced by different geometric parameters. The result can be the reference for A-pillar design. Next, this study simulates the distortion defects influenced by different geometric parameters. By studying the stress distribution on different cases, the mechanism of distortion can be discussed. Furthermore, strategies, like drawbead and die compensation, are used to reduce distortion. This study proposes two die compensation methods for distortion which solve the problem that punch have no space to stamp after compensation. The result in reducing distortion is significant, from 9 degrees to 1.5 degrees. At last, a curved hat channel die has been designed.