Condition Monitoring of Ultra-Precision Cutting Process of Brittle Material using Sensor Fusion and its Optimum Control

在玻璃、陶瓷等脆性材料的切割加工过程中，由于脆性断裂，经常会出现切屑现象。然而，已知的切屑主要是在小于临界厚度的小未变形切屑厚度下塑性变形而产生的，加工表面光滑无凹坑。由于塑性变形而产生切屑的切割过程称为延性模式切割。由于影响延性模式切削的因素很多，目前尚不清楚这些因素对延性模式切削稳定性的影响有多大。因此，本研究的目的是通过自适应控制，找出有效的参数来监控切割过程，以稳定延性模式的切割过程。用…单晶金刚石刀具在超精密平面车床上加工单晶硅刀具时，测量了刀具系统的切削力、声发射信号和振动加速度更多的是在尖端的小倒角，这是市场。用于脆性材料的超精密加工。结果表明：(1)进给速度为0.5gm/rv的加工为延性模式，进给速度为1.75gm/rv的加工为脆性模式，进给速度为1.0um/rv的加工为混合模式，即切屑是由塑性变形和脆性断裂形成的。(2)延性模式旋转切削力的动态分量较小，由于晶体结构的原因，声发射信号包络较大。另一方面，在声发射信号包络较大的工件转角处的脆性模式下，动态推力较大。(3)脆性模式下的声发射包络信号、刀具系统振动加速度的均方根值及其在刀具系统固有频率3 kHz处的振动幅值在脆性模式下均大于延性模式和混合型刀具。(4)单位切割断面面积的静推力，延性模式大于脆性模式和混合型。较少

Surface of workpiece is commonly removed as chips due to brittle fracture in a cutting process of brittle materials like glass and ceramics. However, it is known that the chips can be mainly generated due to plastic deformation at small undeformed chip thickness less than the critical thickness and the machined surface is smooth without pit. The cutting process in which the chips are generated due to plastic deformation is called ductile mode cutting. As there are a lot of factors affecting ductile mode cutting, it has not been clarified how much the factors affect stability of ductile mode cutting. Consequently the purpose of this study is to find out effective parameters for monitoring of cutting process to stabilize ductile mode cutting process by using adaptive control. Cutting forces, AE signals and vibration acceleration of cutting tool system were measured while single crystal silicon workpice was machined on a ultra-precision face lathe by using a single crystal diamond tool wi … More th small chamfer at cutting edge, which is being marketk. for ultra-precision machining of brittle materials. As a result, the followings are concluded from the experiments described above: (1) Machining at feed rate of 0.5 gm/rev is ductile mode, machining at feed rate of 1.75 gm/rev is brittle mode and machining at feed rate of 1.0 um/rev is mixed mode: that is, the chips were generated due to plastic deformation and brittle fracture. (2) Dynamic component of thrust force was smaller in the ductile mode cutting at rotational angle where envelope of AE signal was largar due to crystalline structure. On the other hand, dynamic thrust force was larger in the brittle mode cutting at rotational anglo of workpiece where envelope of AE signal was larger. (3) Mean values of AE envelope signal, RMS value of vibration acceleration of cutting tool system and its vibration amplitude at frequency of 3 kHz, which was natural frequency of cutting tool system, were larger in the brittle mode cutting more than in the ductile and mixed mode cuttings. (4) Static thrust force per unit area of cutting cross section was larger in the ductile mode cutting more than in the brittle mode and the mixed mode cuttings. Less