| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
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
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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
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