利用LS-DYNA 探討切削速度對金屬正交切削切屑形成之影響

The Effects of Cutting Velocity on the Chip Formation in Orthogonal Metal Cutting Using LS-DYNA

陳偉賓(We-Bin Chen)

指導教授 ： 戴兢志

大同大學/工程學院/機械工程學系所/碩士(2005年)

摘要

本研究利用有限元素分析軟體LS-DYNA建立一套金屬正交切削過程的模擬分析模型，藉由模擬真實的金屬正交切削過程可以瞭解切屑形成時的應力、應變等物理量的變化，以助於提高成品尺寸精度和改善成品品質。分析模型採用理想彈塑性材料的構成方程式來描述含碳量0.18%低碳鋼材料的行為，並且採用物理條件型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準則。此模型經分析所得之切削力分佈趨勢與大小和文獻所提供的實驗值相當接近，故可知本研究所建立的模型在定性上是合理的。
本研究擬利用此模型探討不同的切削速度和高速對切屑形成的影響。研究結果顯示，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；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。切屑剪切平面之剪切角會隨著切削速度的增加而增加。刀具-切屑接觸長度也會隨著切削速度的增加而逐漸增加，但黏滯區所佔的比例卻隨切削速度的增加而降低。

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 LS-DYNA is used to establish a set of simulation analysis model of a process of a set of metals
orthogonal cutting. The physical quantity such as the stresses and the strains
can be understood when the chip is formed by simulating the real process of metals orthogonal cutting; this is useful for the enhancing the dimensional
accuracy and he improvement of the production. The formulation used in the
analysis model is used to describe the behavior of the 0.18%mild steel material and the physical condition chip separate criterion is used to be the
criterion of the judgement if the undeformed chip separate from the workpiece to form the chip. The tendency of distribution of the cutting forces is very close to the experimental value from the reference, so the model established in this research is reasonable qualitatively.
In this research this model is used to discuss the affections on the chip form at the difference velocity and the high velocity. The results show that the largest effective stress is caused in the primary deformation zone. This shows that the caused deformation is in the primary deformation zone and the largest effective plastic strain is caused in the surface of the tool-chip because of the friction. The shear angle in the shear plane will crease with the cutting velocity. The contact lengths of tool-chip also crease with the cutting velocity but the ratio in the sticking region will increase with the cutting velocity.

並列關鍵字

Finite Element Analysis、Orthogonal Metal Cuttin

參考文獻

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