CAJ | 학술논문

针对淬硬钢 SKD11硬切削形成的锯齿形切屑，通过金相显微镜和扫描电子显微镜(SEM)观察了切屑的金相组织和微观形貌，分析了不同的切削速度下锯齿形切屑的特点，讨论了绝热剪切发生时剪切带内动态剪应力和温度的变化规律。研究结果表明：SKD11硬切削在低速和高速切削时均产生锯齿形切屑；提高切削速度有利于锯齿化程度的增加；锯齿形切屑的形成同时存在断裂和绝热剪切两种机制，并且随着切削速度的提高，切屑由周期断裂型向绝热剪切型转变；在绝热剪切过程中剪应力变化呈现二次曲线形式，且切削区温度对动态剪应力变化曲线具有较显著的影响；通过提高切削速度可以提高切削温度，抑制材料的硬化效应，引发剪切失稳，从而减小切削力。
침대쉬경강 SKD11경절삭형성적거치형절설，통과금상현미경화소묘전자현미경(SEM)관찰료절설적금상조직화미관형모，분석료불동적절삭속도하거치형절설적특점，토론료절열전절발생시전절대내동태전응력화온도적변화규률。연구결과표명：SKD11경절삭재저속화고속절삭시균산생거치형절설；제고절삭속도유리우거치화정도적증가；거치형절설적형성동시존재단렬화절열전절량충궤제，병차수착절삭속도적제고，절설유주기단렬형향절열전절형전변；재절열전절과정중전응력변화정현이차곡선형식，차절삭구온도대동태전응력변화곡선구유교현저적영향；통과제고절삭속도가이제고절삭온도，억제재료적경화효응，인발전절실은，종이감소절삭력。
Chips in hard cutting of hardened steel SKD1 1 were collected and observed by metallo-graphic microscope and SEM;chip metallurgical textures and configuration under different cutting speeds were investigated.Dynamic shearing stress and temperature in adiabatic shear zones were dis-cussed.Results show that in hard cutting of SKD1 1,saw-tooth chips are formed under both of low and high cutting speeds.Degree of segmentation increases with the increase of cutting speed.The saw-tooth chip formation could be due to fracture and adiabatic shearing;and with the increase of cutting speed,the chip formation mechanism changes from fracture to adiabatic shearing.During adiabatic shearing process,shearing stress develops as a quadratic curve,and cutting temperature shows dis-tinct influence on the dynamic shearing stress.By increasing cutting speed,cutting temperature can be increased,which will weaken the hardening effect and reduce the maximum shear stress,cause oc-currence of shearing instability and then reduce cutting force.