戰機起落架鍛件之鍛造製程研究開發

外套筒與活塞為戰機起落架關鍵零件，材料分別為AL7050與300M，因具鍛造製程之難度與無大型鍛壓設備，國內尚未有實際鍛製成功之案例。本文依中科院設計之零件建立鍛造圖面，若傳統閉模鍛造，負荷最大為約25,000 ton。但國內最大鍛機只有12,000 ton，根本無法鍛造。且傳統鍛造在毛邊剪斷處有鍛流線外露現象，為疲勞破壞起源點，造成耐疲勞性不佳。因此為降低鍛造負荷，避免因毛邊的生成，擬設計多軸複動化閉塞鍛造模具，進行無毛邊鍛造成形。首先以DEFORM進行鍛造製程模擬，其成形負荷，活塞鍛造為2,100 ton，外套筒鍛造為4,500 ton左右，鍛件沒有缺陷。經實際開模鍛造，成形負荷分別為2,500 ton 與4,000 ton左右，與模擬結果接近。鍛件經過量測與機械性質測試，均符合產品設計要求。顯示多軸複動化閉塞鍛造模具可降低鍛造負荷，克服國內鍛機能力不足之問題點，鍛造出起落架鍛件，也是國內首次自主開發成功之案例。

關鍵字

外套筒；活塞；多軸複動化；閉塞鍛造

並列摘要

The outer housing and piston are the key components of the landing gear in the fighter. The materials are special, which are AL7050 and 300M. There is no case on forging these parts successfully in domestic due to the difficulties in the forging process and lack of large forging equipments. In this article, the drawings of the forgings are established according to the designs of the landing gear parts by NCSIST.The load needs around 25,000 ton, higher than the biggest forging press of 12,000 ton in domestic. So, it is impossible to forge theses part in domestic. Besides, the exposure of the end of flow line after trimming will results into the poor fatigue property due this being the starting points for the cracks. So, the multi-ram and multi-action enclosed dies are designed, instead of the flash forging die, to prevent the above problems and to decrease the load. First, the DEFORM software is used to simulate the forging process and show no forging defects occurred and the flow line is reasonable. The maximum forging loads of the piston and outer housing are 2100 ton and 4500 ton respectively. Then, the actual forging is proceeded. The forging loads of the piston and outer housing are 2500 ton and 4000 ton respectively, which are closed those in the simulation. After the measurements, the dimensions and the mechanical properties of the forgings conform to the requirements of the specifications. It shows that the multi-ram and multiaction enclosed dies can lower the forging load to overcome the problem of the lack of the capabilities of the press in domestic. Then the forgings of the piston and the outer housing are developed. This is the first time to develop these parts successfully in domestic.