旋壓成型可靠度分析之研究

A Study of Reliability Analysis for Metal Spin-forming

數控旋壓成形技術充分利用了數控加工中心的彈性，對零件的最終形狀、成形軌跡、旋壓轉速、滾輪進給速度等參數進行任意調整，可以旅壓田各種不同形狀的零件，具有加工效率高、勞動需求低、無須進行切削加工等特點；在旋壓過程，不同的材質和形狀，需設定不同的加工參數，若參數設定不當，易造成加工失敗（破裂）現象。為改善旋壓成型品質不穩現象，本文採用田口方法之品質工程規劃法，分析不同工程因子對目標品質之影響，不同旋壓成形製程參數的適用範圍，找出製程最佳化之加工參數，以減少分析所需之試模時問及成本浪費。而為提高產品可靠度、降低製造不良率，本文分析不同厚度特性在旋壓加工時可靠度退化情況；探討製程參數對不同厚度及硬度加下影響，針對不同厚度板材探討不同變形比旋壓失效原因，記錄失效時間及旋壓容許範圍，利用可靠度分析之基本理論及參數估計之方法，求出失效分佈之參數值，再以K-S適合度檢定之方法，判斷產品最適之失效分佈，藉以得知旋壓過程中不同變形比之可靠度變化，以為製程參數調整及旋壓風險評估之依據。

The NC spin-forming machine center possesses excellent manufacturing properties such as high mechanical efficiency and low manpower need. It can quickly form the final shapes of parts and doesn't need more work to cut the material for the formed parts by adjusting the parameters of shaped trajectory, spinning speed and feeding rate, etc. Different processing parameters are usually needed for different materials and shapes. If the parameters set improperly, spinning failure would be incurred including break-splitting and wrinkling. In order to avoid spinning failure and obtain good quality, this paper investigates the influence of manufacturing parameters on spinning by using the Taguchi method. The purpose is to find out the optimal manufacturing parameters so as to shorten the time needed for trial and to find out the optimal manufacturing parameters.Moreover, spin-forming reliability of stainless plate on different thicknesses and lengths was also studied to evaluate the successful probability of products on spin-forming. The storage tank of a plastic shot machine is chosen as the researched object. The manufacturing parameters were set according to the results obtained in the Taguchi analysis. The allowed spun lengths of the storage tank in different thicknesses were collected to evaluate spinning reliability in cooperation with K-S identification. The purpose is to find out the relationship between the allowed spinning deformation and the thicknesses of stainless plate. The studied results can be used as a basis in manufacturing parameter adjustment and risk assessment of spin-forming.