刃口钝圆半径对硬质合金刀具断续切削性能的影响  

Influence of Cutting Edge Radius on Interrupted Machining Performance of Cemented Carbide Tools

作　　者：燕洋妞 何世文[1] 陈展 林孝良 林益斌 Yan Yangniu;He Shiwen;Chen Zhan;Lin Xiaoliang;Lin Yibing(College of Materials and Advanced Manufacturing,Hunan University of Technology,Zhuzhou Hunan 421007,China;Zhuzhou Huarui Precision Cutting Tools Co.,Ltd.,Zhuzhou Hunan 421000,China)

机构地区：[1]湖南工业大学材料与先进制造学院,湖南株洲412007 [2]株洲华锐精密工具股份有限公司,湖南株洲412000

出　　处：《硬质合金》2025年第2期133-144,共12页Cemented Carbides

基　　金：湖南省自然科学基金项目(2020JJ6069);湖南工业大学研究生科研创新项目资助(CX2305)。

摘　　要：采用硬质合金刀具进行断续切削时,切削刃在远未达到磨损失效标准之前就因断裂而发生早期破损,经过刃口钝化后,能提高刀具的抗冲击性能和稳定性,降低刀具的破损。本文采用不同刃口钝圆半径r_(β)的刀具进行断续车削,实验研究表明,r_(β)对刀具的耐冲击性能影响明显。在70~120 m/min的低切削速度时,硬质合金刀具的主要失效形式是刀尖崩碎,其破坏机理为:初始裂纹在表层涂层处萌生,随后以阶梯状扩展模式贯穿涂层结构,最终穿透至硬质合金基体材料,引发宏观脆性断裂;在切削速度为140~210 m/min时,刀具失效的原因主要是热疲劳损伤和机械疲劳的塑性破损。在一定范围内钝圆半径r_(β)越大,刀具的抗冲击性能越好,寿命越长。通过对切削过程中3个阶段的切削力分析发现,在刀具切入和切出的瞬时,切削力随着切削速度的增大而增大,r_(β)对切入时的主切削力F_(y)和切深抗力F_(z)影响较大;连续切削阶段,r_(β)主要对进给力F_(x)和切深抗力F_(z)的影响最大,即r_(β)对切削层的应力和形变影响最大。因此选择合适的刃口钝圆半径对刀具切削过程中的平稳性、抗冲击性、被加工材料质量和刀具寿命的提升至关重要。When employing cemented carbide tools for interrupted cutting operations,the cutting edge often experiences premature failure due to fracture well before reaching the wear failure criteria.Subsequent edge passivation treatment significantly enhances the tools impact resistance and stability,thereby reducing the incidence of tool breakage.This article used cutting tools with different blunt radii r_(β)of the cutting edge for intermittent turning.Experimental research shows that rβhas a significant impact on the impact resistance of the tools.At low cutting speeds of 70~120 m/min,the main failure mode of cemented carbide tools is tip fracture,and its failure mechanism is as follows:initial cracks initiate at the surface coating,then propagate through the coating structure in a stepped pattern,and finally penetrate to the cemented carbide matrix material,causing macroscopic brittle fracture.When the cutting speed is 140~210 m/min,the main causes of tool failure are thermal fatigue damage and plastic damage caused by mechanical fatigue.A larger blunt radius r_(β)within a certain range indicates a better impact resistance and a longer lifespan of the tool.Through the analysis of cutting forces in three stages of the cutting process,it is found that at the moment of tool entry and exit,the cutting force increases with the increase in cutting speed,and r_(β)has a significant impact on the main cutting force F_(y) and cutting depth resistance F_(z) during entry.In the continuous cutting stage,r_(β)has the greatest influence on the feed force F_(x) and the cutting depth resistance F_(z),or in other words,r_(β)has the greatest influence on the stress and deformation of the cutting layer.Therefore,choosing the appropriate blunt radius of the cutting edge is crucial for improving the smoothness,impact resistance,material quality,and tool life during the cutting process.

关 键 词：硬质合金刀具 断续切削 钝圆半径 失效 切削力 

分 类 号：TG711[金属学及工艺—刀具与模具]