摘要
采用有限元仿真方法对ZrO2 陶瓷工件进行三维切削过程的数值模拟,探讨工件材料切削过程中切屑去除机理、应力动态变化与分布规律以及切削力的演变规律等.结果表明:切削过程中刀具的硬接触行为显著影响材料去除,导致切屑崩落、材料开裂和裂纹扩展等失效形式出现.在切削深度分别为 200和250 μm时,工件末端边缘出现大量裂纹,并朝垂直切削方向扩展,导致工件边缘出现大尺寸碎裂.增大切削速度可引起应力和切削力的上下波动,但在整体上没有明显变化.刀具刃圆半径影响切入初期裂纹的形成,随着刃圆半径增大,刀具前端的裂纹长度逐渐缩短,但其对切削力的影响不明显.负的刀具前角切削不会使工件内部产生裂纹,可获得较好的加工质量;此外,在刀具前角为 0°时,其最大切削力最大,但随着刀具前角增加,其平均切削力变化不明显.
Abstract
Objectives:Research on ceramic processing primarily focuses on areas such as single abrasive grinding methods,processing mechanisms,processing efficiency,material removal mechanisms,and surface quality.However,research on ZrO2 ceramic cutting processing is relatively insufficient.Therefore,the 3D cutting process of ZrO2 ceramic workpieces was numerically simulated using the finite element simulation method.The study discusses the mechanism of chip removal,the dynamic change and distribution of stress,and the evolution law of cutting force under various cut-ting conditions.Methods:The 3D cutting process of ZrO2 ceramic workpieces,under different machining parameters and tool parameters,was numerically simulated using the finite element simulation method.The cutting forces under various feed speeds and cutting depths were compared to explore the failure modes and material removal mechanisms of ZrO2 ceramic during the cutting process.Results:The hard contact behavior between the cutting tool and the workpiece significantly affects the material removal process,leading to failure modes such as chip collapse,material cracking,and crack propagation.When the cutting depth is 200 μm or 250 μm,numerous cracks appear at the end edge of the work-piece and expand in the vertical cutting direction,resulting in significant fragmentation at the edge.An increase in cut-ting speed will causes fluctuations in stress and cutting force,but overall,there is no significant change in cutting per-formance.The radius of the cutting edge affects the formation of cracks in the initial cutting stage.As the edge radius in-creases,the length of the crack at the front end of the tool shortens,though the impact on cutting force is not significant.A negative tool rake angle during cutting does not induce cracks in the workpiece,and it leads to better machining qual-ity.In addition,when the tool rake angle is 0 °,the maximum cutting force increases rapidly,but the cutting force vari-ation is not obvious with increasing rake angle.Conclusions:As the cutting depth increases,the stress layer on the tool surface gradually expands from the tip to the front and rear cutting surfaces,and gradually increases.As the cutting depth increases,local cracks form at the cutting end of the workpiece and propagate downward.The position of maxim-um stress on the front cutting surface of the tool gradually increases with the increase in edge radius.However,the influ-ence of the edge radius on the cutting force is relatively small.When cutting ZrO2 ceramics with a tool featuring a negat-ive rake angle,no internal cracks are caused,and good machining quality can be achieved.
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