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Evaluation of machinability in milling by controlling chip thickness using NC simulation
Makoto Nikawa,Masato Okada,Hiroki Mori,Yasuhiro Fujii,Minoru Yamashita 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.10
In this study, the machinability of the machining method for controlling chip thickness during the cutting operation was evaluated using simulation based on NC data. A comparative three-dimensional cutting test with a ball end mill was performed using both original and modified NC data. The modified NC data was created for the purpose of controlling the chip thickness generated when cutting with a constant rotation value and changing the feed rate of the original NC data. The results indicated that the actual chip thickness exceeded that of the calculated value although the thickness fluctuation was suppressed. The results revealed that the maximum cutting force and the fluctuation range of cutting force were low, and tool wear after cutting was suppressed using the modified NC data. The application of the method to the cutting of complicated shapes with high removing volume led to reductions in the cutting time by 31 %.
Yoshio Nikawa,Akira Ishikawa 한국전자파학회JEES 2010 Journal of Electromagnetic Engineering and Science Vol.10 No.4
Recent development of magnetic resonance imaging (MRI) equipment enables interventional radiology (IVR) as diagnosis and treatment under MRI usage. In this paper, a new methodology for magnetic resonance (MR) scanner to apply not only diagnostic equipment but for treatment one is discussed. The temperature measuring procedure under MR is to measure phase shift of T₁, which is the longitudinal relaxation time of proton, for the position inside a sample material with the application of pulsed RF for heating inside the sample as artificial dielectrics. The result shows the possibility to apply MR as temperature measuring equipment and as a heating equipment for applying such as hyperthermia heating modality.
Cutting characteristics of twist drill having cutting edges for drilling and reaming
Masato Okada,Naoki Asakawa,Yusuke Fujita,Makoto Nikawa 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.5
In this study, the cutting characteristics of a drill reamer, which has conventional twist drill cutting edges appended for reaming, wereinvestigated. A drill reamer has three types of cutting edges, whose roles are drilling, semi-finishing, and finishing. The cutting characteristicsof a conventional twist drill were compared to those of the drill reamer. The cutting characteristics were evaluated using the thrustforce, cutting torque, surface roughness, wear behavior of the cutting edges, and cutting edge temperature. The study used a workpiecemade of carbon steel. The temperature of the cutting edge for reaming reached a maximum value of approximately 420°C, even thoughthe depth of the cut was very small. The inner surface roughness with the drill reamer was superior to that with the conventional drill,even under dry and low-speed cutting conditions. The abrasive wear observed on the margin face of the cutting edge used for reaming.
Ju, H.,Kim, T.,Chung, C.-M.,Park, J.,Nikawa, T.,Park, K.,Choi, I. PHARMACEUTICAL SOCIETY OF JAPAN 2017 Biological & pharmaceutical bulletin Vol.40 No.5
<P>The homeostasis of muscle properties depends on both physical and metabolic stresses. Whereas physical stress entails metabolic response for muscle homeostasis, the latter does not necessarily involve the former and may thus solely affect the homeostasis. We here report that metabolic suppression by the hypometabolic agent 3-iodothyronamine (TIAM) induced muscle cell atrophy without physical stress. We observed that the oxygen consumption rate of C2C12 myotubes decreased 40% upon treatment with 75 mu m T1AM for 6h versus 10% in the vehicle (dimethyl sulfoxide) control. The TIAM treatment reduced cell diameter of myotubes by 15% compared to the control (p<0.05). The cell diameter was reversed completely by 9h after TIAM was removed. The TIAM treatment also significantly suppressed the expression levels of heat shock protein 72 and alpha B-crystallin as well as the phosphorylation levels of Akt1, mammalian target of rapamycin (mTOR), S6K, forkhead box O1 (FoxO1) and FoxO3. In contrast, the levels of ubiquitin E3 ligase MuRF1 and chymotrypsin-like activity of proteasome were significantly elevated by TIAM treatment. These results suggest that T1AM-mediated metabolic suppression induced muscle cell atrophy via activation of catabolic signaling and inhibition of anabolic signaling.</P>
Kohno, Shohei,Yamashita, Yui,Abe, Tomoki,Hirasaka, Katsuya,Oarada, Motoko,Ohno, Ayako,Teshima-Kondo, Shigetada,Higashibata, Akira,Choi, Inho,Mills, Edward M.,Okumura, Yuushi,Terao, Junji,Nikawa, Takes American Physiological Society 2012 environmental and exercise physiology Vol.112 No.10
<P>Skeletal muscle is one of the most sensitive tissues to mechanical loading, and unloading inhibits the regeneration potential of skeletal muscle after injury. This study was designed to elucidate the specific effects of unloading stress on the function of immunocytes during muscle regeneration after injury. We examined immunocyte infiltration and muscle regeneration in cardiotoxin (CTX)-injected soleus muscles of tail-suspended (TS) mice. In CTX-injected TS mice, the cross-sectional area of regenerating myofibers was smaller than that of weight-bearing (WB) mice, indicating that unloading delays muscle regeneration following CTX-induced skeletal muscle damage. Delayed infiltration of macrophages into the injured skeletal muscle was observed in CTX-injected TS mice. Neutrophils and macrophages in CTX-injected TS muscle were presented over a longer period at the injury sites compared with those in CTX-injected WB muscle. Disturbance of activation and differentiation of satellite cells was also observed in CTX-injected TS mice. Further analysis showed that the macrophages in soleus muscles were mainly Ly-6C-positive proinflammatory macrophages, with high expression of tumor necrosis factor-α and interleukin-1β, indicating that unloading causes preferential accumulation and persistence of proinflammatory macrophages in the injured muscle. The phagocytic and myotube formation properties of macrophages from CTX-injected TS skeletal muscle were suppressed compared with those from CTX-injected WB skeletal muscle. We concluded that the disturbed muscle regeneration under unloading is due to impaired macrophage function, inhibition of satellite cell activation, and their cooperation.</P>