粉末冶金之正齒輪精度改善

Abstract

粉末冶金之正齒輪精度改善 學生:張宏彬 指導教授:蔡忠杓 博士 國立交通大學機械工程研究所 摘 要 齒輪為重要的機械傳動元件。目前工業上所使用的金屬齒輪製造方法，包括傳統的滾齒、刨齒、齒輪銑製、線切割等切削加工，以及鍛造、壓鑄、射出成形、粉末冶金等成形製造方法。其中，粉末冶金製造齒輪具有省料、省工、適合大量生產和成本低等優越性，而且機械性質良好，已廣泛地使用於汽機車零件、電動工具及家電產品當中。 唯當齒輪於實際製造過程中，由於成形及燒結條件的影響，造成原來所沖壓之胚體其尺寸安定性不足的缺點，使得粉末冶金之齒輪的齒面幾何誤差幾乎難以避免，因此導致齒輪在嚙合運轉時會產生運動誤差，並引起齒輪之振動及噪音。隨著粉末冶金齒輪強度之不斷提升，此類齒輪之應用範圍與市場亦呈逐漸增加的趨勢，然而客戶及使用者對產品的要求也日漸提升，因此業者對於粉末冶金齒輪品質的提升也變得更殷切；為了降低齒輪傳動誤差、改善齒輪的振動及噪音，提高齒輪製造精度乃是首要之務。欲得高精度的齒輪，齒形之尺寸與變形的控制尤為重要，因此，合適的成形模具之設計與製造，攸關成品的優劣。 本論文將參照實務上生產製造粉末冶金齒輪的條件，進行試作實驗及齒輪精度量測，以探討粉末冶金製程參數與齒輪精度之間的關係；並應用齒輪創成原理所推導之正齒輪數學模式，進行齒輪參數及齒面變異的敏感度分析。進而比較實驗量測結果與電腦模擬分析之結果，以求得較理想的齒輪模具參數修整，俾使粉末冶金齒輪在製造過程中所產生的齒面變形能得到適當的補償，以達到高精度粉末冶金齒輪的要求。

Improvement on the Precision of Powder Metallurgy Spur Gears Student：Hung-Pin Chang Advisor：Dr. Chung-Biau Tsay Institute of Mechanical Engineering National Chiao Tung University Abstract Gear is one of the important transmission elements of machine system. The conventional cutting manufacture methods of gears, including gear hobbing, gear shaping, gear milling, gear wire cutting, ect. As to the forming processes of manufacture methods including forging, die-casting, injection molding and sintered powder-metal gears. Among them, the sintered powder-metal gear not only has great advantages of material-saving, labor-saving, cost reduction and suitable for mass production, but also has good mechanical properties for the gears. It has been widely used in automobiles, electrical machines and household appliances. In the powder-metal gear manufacturing, due to the influences of forming and sintering conditions, the unstable defect on the green compact parts’ dimensions, results in the gear profile geometric errors. Consequently, the gear transmission errors, vibration and noise occur during the gear pair meshing. Therefore, it is most important to improve the gear manufacture precision to reduce the gear transmission errors, vibration and noise. To obtain a high precision gear, the control of gear dimensions and variations is important. Therefore, design and manufacture of a good shape of forming die decide the products’ quality. This study refers to the conditions of practical powder-metallurgy manufacture process, and proceeds to experiments and gear precision measurements as well as investigation on the relationship of the powdwer-metallurgy parameters and gear precision. Furthermore, the mathematical model for spur gear is developed based on the theory of gearing, and sensitivity analyses of gear parameters and gear surface deviations are performced. Then, comparison with the results of experiments and computer simulations, in attempt to evaluate an ideal amendment on the parameters of a forming die. It enables a suitable compensation on gear surface deviations which resulted from the powder-metallurgy process, and attains a high precision powder-metallurgy gear.