高壓氣瓶縮口與鉚合沖壓模具之改善

Improvement of Sinking and Riveting Dies in Stamping High Pressure Gas Vessels

蔡岳洋(Yue-Yang Tsai)

指導教授 ： 林恆勝

國立虎尾科技大學/工程學院/創意工程與精密科技研究所/碩士(2010年)

https://doi.org/10.6827/NFU.2010.00045

摘要

迷你高壓氣瓶的製造程序為先將鋼卷下料為圓形板胚後進行傳送沖壓加工。首先實施六道次深引伸為高長徑比之圓底管件，接著實施一道次縮口預成形後在瓶口實施高週波退火軟化，再實施六道次縮口成形，縮口成形後的管件經端口修邊後再充填氣體並鉚合完成封裝。
本研究使用DEFORM-2D套裝軟體模擬迷你高壓氣瓶多道次縮口與鉚合製程，探討二種不同設計理念的縮口模具，分別為使用固定圓角六道次縮口模具及使用遞增圓角之五道次縮口模具，減少縮口道次可節省模具開發及保養成本，但必須在圓角設計上，求得較佳的圓角增量。本文探討不同道次製程及圓角增量對於成形負荷、管件的等效應變、破壞值及厚度變化的影響。鉚合模具的斷面形狀有斜角及圓角兩種設計，由於鉚合後的管件在瓶口端偶而會有褶痕的現象，會使人以為是缺陷，將以模擬鉚合成形以探討褶痕的成因。
固定圓角六道次縮口製程縮減為五道次造成個別道次負荷上升，對管件則產生稍微增大的等效應變及厚度。遞增圓角的設計中，模具負荷及管件厚度隨著圓角增量的增加而增加，顯示圓角增量愈大則模具與管件的摩擦面積愈大所造成，而隨著圓角增量的增加可明顯降低管件內部及表面較高的等效應變的現象，使等效應變分佈較平均而改善變形均勻度，且壁厚會有微量的增加；管件最大破壞值發生於管件內側且隨著圓角增量的增加而下降的愈明顯。
鉚合後較大的等效應變皆發生在管件端口，其中最大值發生管件端口外表面位置；圓角設計模具其等效應變最大值小於斜角的設計，亦可得到較佳的變形均勻度。當最大等效應變集中於管件端口部位，且受到周向擠壓的作用下易造成褶痕；若要改善褶痕的現象，採用圓角設計的模具可改善管件端口的等效應變。最大破壞值發生在鉚合後圓角的位置，代表圓角處較易產生破裂，而斜角與圓角設計的最大破壞值相當接近，模擬顯示最大破壞值與褶痕並未發生在同一部位，因此成品鉚合後偶發的褶痕現象應屬材料自軸外朝徑向流動時，材料互相推擠所造成，而不是裂痕。

關鍵字

高壓氣瓶 ； 沖壓 ； 縮口 ； 鉚合

並列摘要

The manufacturing process of high pressure vessels comprises blanking from steel coil and followed with transfer stamping operations. The circular blank is deep drawn into a high length-to-diameter ratio tube in six-stage transfer stamping. The workpiece is then sunk on its open end and annealed with induction heating. The preform is further sunk with six-stage transfer stamping. The tube is then milled on the open end and filled with high pressure gas and riveted to its completion.
This work applies finite element software DEFORM 2D to simulate both the sinking and riveting process. Two die-design concepts were examined which include six-stage with fixed die radius and five-stage with variational die radius. The effects of die radius on the forming load, effective strain, damage and thickness were investigated. The riveting dies have dual-taper and round-fillet types. The occurrence of folding defect will be investigated with these two types.
The results show that the forming load, effective strain, damage and thickness will slightly increase as the sinking process reduces from six to five stages. Both the maximum effective strain and maximum damage value occur on the inner wall tube. As for the five-stage sinking with variational die radius, forming load increases with die radius because of the increase of contact surface between the die and workpiece. The effective strain and damage decreases indicating more homogeneous deformation in forming a larger die radius. Tube thickness increases slightly with die radius.
Maximum effective strain occurs on the rim while the maximum damage value occurs on the corner after the riveting process. This indicates that the occurrence of the fold defect is caused by the squeeze of the material flowing radially from the outer corner into the inner rim. However, fracture is not likely to occur during the riveting process. Effective strain is slightly lower in riveting with round-fillet type.

並列關鍵字

high pressure vessel ； stamping ； sinking ； riveting

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