應用ANSYS/LS-DYNA模擬正交金屬切削切屑 形成機構及溫度之研究

The Simulation of Chip Formation and Temperature in Orthogonal Metal Cutting Using ANSYS/LS-DYNA

洪士烜(Shih-Hsuah Hung)

指導教授 ： 戴兢志

大同大學/工程學院/機械工程學系所/碩士(2008年)

摘要

本研究論文應用有限元素分析軟體 ANSYS/LS-DYNA 建立一套具有熱力耦合效應的金屬正交切削模型，並藉由模擬真實的金屬正交切削過程瞭解切屑形成時的應力、應變等物理量的變化，以及工件與切屑的溫度分佈，以助於提高成品尺寸精度和改善成品品質。分析模型材料採用Johnson and Cook的動態構成方程式來描述含碳量0.18%低碳鋼材料的行為，並且採用元素破壞產生的切屑剝離準則作為未變形之切屑是否自工件剝離而形成切屑的判斷標準。
研究結果顯示有限元素分析結果與實際切削實驗結果的趨勢相當接近。最大的等效塑性應變值產生在刀具-切屑接觸面，其原因為摩擦所造成；最大的等效應力值發生在主要變形區裡，顯示切削過程的變形產生在主要變形區；切屑剪切平面之剪切角會隨著切削速度的增加而增加；最高溫度則發生在刀面－切屑接觸面上且距刀尖有一定距離的地方，切削條件中以切削速度、刀具斜角、摩擦係數對切削溫度影響最大，而切削寬度、切削深度對切削溫度的影響不大，此結果與切削理論相符。

關鍵字

有限元素分析 ； 金屬正交切削

並列摘要

In this research, the finite element analysis software ANSYS/LS-DYNA is used to establish a thermo-mechanical coupling model to simulate the orthogonal metal cutting processes. With the aid of simulating the orthogonal metal cutting process, the variation of the stress, strain and temperature in the workpiece and the chip can be obtained during the chip formation. These results are useful to enhance the dimensional accuracy of the products and to improve the quality of the products. The Johnson and Cook dynamic constitutive material model is used to describe the behavior of the 0.18 % mild steel material. The chip separate criterion is based upon the failure criterion of the workpiece. Good correlation can be concluded between experimental and simulation with cutting force and the distribution of temperature. The largest effective plastic strain is located at the tool-chip interface because of the friction. The largest effective stress is located at the primary deformation zone. The shear angle in the shear plane will increase with the cutting velocity. The maximum temperature is occurred at a distance from the tool tip and on the tool-chip interface. Furthermore, the cutting velocity, rake angle, and the coefficient of friction have a great effect upon the temperature. The results were in good correlation with the theory of metal cutting.

並列關鍵字

Finite element analysis ； Orthogonal metal.cutting

參考文獻

[5]K. Iwata, K. Osakada and Y. Terasaka, “Process modeling of orthogonal cutting by the rigid-plastic finite element method”, Trans. ASME, J. Engng. Material and Technology, Vol. 106, pp.132-138, 1984.

[6]J. S. Strenkowaski and J. T. Carroll III, “A finite element model of orthogonal metal cutting”, Trans. ASME, Journal of Engineering for Industry, Vol.107, pp.349-354, 1985.

[7]J. S. Strenkowaski and K. J. Moon, “Finite element prediction of chip geometry and tool/workpiece temperature distribution in orthogonal metal cutting”, Trans. ASME, Journal of Engineering for Industry, Vol.127, pp.313-318, 1990.

[8]K. Komvopoulos and S. A. Erpenbeck, “Finite element modeling of orthogonal metal cutting”, Trans. ASME, Journal of Engineering for Industry, Vol.113, pp.253-267, 1991.

[9]B. Zhang and A. Bagchi, “Finite element simulation of chip formation and comparison with machining experiment”, Trans. ASME, Journal of Engineering for Industry, Vol.116, pp.289-297, 1994.