Simulation on dynamic characteristics of TC4 cutting with crack defects

裂纹缺陷下TC4切削加工动态特性仿真

Titanium alloys play an important role in aerospace and other fields.However,after precision forging and cold rolling process,some defects will appear on the subsurface of titanium alloy bars,thus reducing the surface quality and precision of turning process.This study aimed at exploring the effect of crack defects on TC4 cutting.Firstly,the finite element cutting simulation model of TC4 material with crack defects was established in ABAQUS.Then,the cutting parameters such as cutting force,stress concentration,chip morphology,residual stress were obtained by changing the variables such as the size and height of crack defects.Finally,the turning experiment was carried out on centerless lathe.The results show that the cutting force changes abruptly when the defect position is located on the cutting path,the maximal stress occurs at the tip of the defect,and the mutation of stress value is more serious with the increase of defect size;the buckling deformation of chip morphology occurs and becomes less serious with the increase of the distance between the defect position and the workpiece surface;the surface residual stress near the defect is related to the stress when the tool is close to the defect,the larger defect size and the closer to the machined surface,the greater the residual stress.Therefore,under certain processing conditions,the TC4 material should avoid large size defects or increase the distance between defects and the machined surface,so as to obtain better and stable surface quality.

钛合金在航空航天等领域发挥着重要作用。由于精锻、冷轧后的钛合金棒材亚表面易产生裂纹缺陷,本研究将探究其对TC4材料切削加工的影响。首先,利用ABAQUS构建了含裂纹缺陷的TC4材料有限元切削仿真模型。其次,通过改变裂纹缺陷的尺寸和高度等变量得到切削力、应力集中、切屑形状、表面残余温度和残余应力等参数。最后,在无心车床上进行了切削实验。结果表明,当裂纹缺陷位置处于切削路径时,切削力会产生突变,在缺陷尖端点处出现最大应力值,且应力值随裂纹尺寸增大而增大;切屑形态也发生了屈曲变形,其随缺陷位置与工件表面距离的增加而减小;裂纹缺陷附近的表面残余应力与裂纹尺寸大小和刀具靠近缺陷时的应力大小相关,尺寸较大且靠近加工表面的缺陷会导致更大的残余应力。因此,在加工条件一定的情况下,钛合金材料应避免出现尺寸较大的缺陷或者通过增加缺陷与加工表面之间的距离,以确保良好和稳定的表面质量。