六角螺栓近淨形頂鍛成形模擬

Simulation of Near-net-shape Forging for Hexagonal Bolts

林恆勝(H. S. Lin) ； 許源泉(Y. C. Hsu) ； 楊東昇(T. S. Yang) ； 楊政峰(C. F. Yang) ； 歐聖堂(S. T. Ou)

《鍛造》 16卷1期 (2007/06) Pp. 5-12

https://doi.org/10.29791/Forging.200706.0002

摘要

六角螺栓頭端通常以冷間頂鐵成形製程來製造，由於冷間頂鐵屬於開模鍛造，模具設計較容易，但需以剪緣模再對蕈狀頭端沖剪成為六角頭，此剪緣後的廢料量不容忽視，尤其對於長度較小的螺栓，或其它應用於緊扣件的高級合金而言，藉由減少廢料以提高產品毛利的需求日益迫切。因此本研究導入近淨形鍛造的觀念於六角螺栓的成形加工，以達到無廢料的理想，並以金屬成形的有限元素DEFORM 3D軟體進行模擬，探討可行之近淨形設計。
本研究經由模擬試誤法，循序探討四種六角螺栓近淨形頂鍛成形方案：(1)成形方案一：改良傳統六角螺栓頂鐵製程之第一道次預鍛粗為密閉式圓錐型式之預成形。(2)成形方案二：再改良前述道次預成形為六個圓錐面與六個角錐面組合而成的特殊六角／圓錐複合型式。(3)成形方案三：再改良第二道次之上模仁為特殊六角／圓錐複合型式，以圓錐面成形六角螺栓的對角部位、角錐面成形六角螺栓的對邊部位。(4)成形方案四：再進一步改良成形方案三之圓錐面和角錐面兩部位之表面粗糙度，藉由不同的模仁表面粗糙度，來控制其材料流動，此方案可達成六角螺栓近淨形成形的目標。

關鍵字

六角螺栓 ； 冷間項鐓 ； 近淨形

並列摘要

Hexagonal bolts are usually formed with cold heading. The process is classified as open-die forging and therefore its die design is less complicated. The mushroom-like head has to be sheared into hexagonal shape and the amount of the scrap is somehow significant especially for heading with short bolts or high alloy material. There is an increasing demand in increasing the gross profit by increasing the yield of workpiece material. Therefore this work aims to apply the concepts of near-net-shape forging to the forming of hexagonal bolts. FE software DEFORM 3D was utilized to simulate and verify the proposed forming schemes to achieve this end.
There were four different forming schemes of near-net-shape proposed by trial-and-error as follows. Scheme 1: modify the first stage of the conventional heading into close-die forging of cone shape. Scheme 2: modify the aforementioned stage into a special ”hexagonal-and-cone” compound shape comprising of six conical faces and six inclined faces. Scheme 3: further modify the second stage into another special ”hexagonal-and-cone” compound cavity. Its conical face was applied to constrain the flat side while the inclined face was applied to constrain the diagonal corner of the hexagonal head. Scheme 4: assign different surface roughness on the conical and inclined surfaces of the two respective ”hexagonal-and-cone” compound cavities. The goal of near-net-shape forging could be achieved by this measure.

並列關鍵字

hexagonal bolt ； cold heading ； near-net-shape