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削加工过程中，由于脆性断裂，工件表面常以切屑的形式被去除。然而，已知的是，在小于临界厚度的小的未变形切屑厚度下，切屑可以主要由于塑性变形而产生，并且加工表面是光滑的而没有凹坑。由于塑性变形而产生切屑的切削过程称为延性切削。由于影响延性模切割的因素很多，这些因素对延性模切割稳定性的影响程度还不清楚。因此，本研究的目的是找出有效的参数监测切削过程，以稳定延性模式切削过程中使用自适应控制。在超精密平面车床上，用单晶金刚石刀具加工单晶硅工件，测量了切削力、声发射信号和刀具系统的振动加速度， ...更多信息 刃口处的小倒角，正在市场上销售。用于脆性材料的超精密加工。结果，从上述实验得出以下结论：（1）在0.5 gm/rev的进给速率下的加工是延性模式，在1.75 gm/rev的进给速率下的加工是脆性模式，而在1.0 um/rev的进给速率下的加工是混合模式：即，切屑是由于塑性变形和脆性断裂而产生的。(2)由于晶体结构的原因，在塑性切削条件下，当切削角度为旋转角时，声发射信号包络线较大，推力的动态分量较小。另一方面，在脆性模式下，在工件旋转角处的动态推力较大，AE信号的包络较大。(3)声发射包络信号的平均值、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处的振幅，脆性切削比韧性切削和混合型切削大。(4)单位切削截面面积的静推力在韧性切削中大于脆性切削和混合切削。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