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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.
Kwon, Hyouk-Bum,Fukuhara, Shigetomo,Asakawa, Kazuhide,Ando, Koji,Kashiwada, Takeru,Kawakami, Koichi,Hibi, Masahiko,Kwon, Young-Guen,Kim, Kyu-Won,Alitalo, Kari,Mochizuki, Naoki Company of Biologists 2013 Development Vol.140 No.19
<P>Blood vessels and neurons grow often side by side. However, the molecular and cellular mechanisms underlying their parallel development remain unclear. Here, we report that a subpopulation of secondary motoneurons extends axons ventrally outside of the neural tubes and rostrocaudally as a fascicle beneath the dorsal aorta (DA) in zebrafish. We tried to clarify the mechanism by which these motoneuron axons grow beneath the DA and found that Vegfc in the DA and Vegfr3 in the motoneurons were essential for the axon growth. Forced expression of either Vegfc in arteries or Vegfr3 in motoneurons resulted in enhanced axon growth of motoneurons over the DA. Both <I>vegfr3</I> morphants and <I>vegfc</I> morphants lost the alignment of motoneuron axons with DA. In addition, forced expression of two mutant forms of Vegfr3 in motoneurons, potentially trapping endogenous Vegfc, resulted in failure of growth of motoneuron axons beneath the DA. Finally, a <I>vegfr3</I> mutant fish lacked the motoneuron axons beneath the DA. Collectively, Vegfc from the preformed DA guides the axon growth of secondary motoneurons.</P>