松坂 壮太

Abstract Wheel scribing on glass generates a vertical crack with a periodic stripe pattern beneath the wheel (hereafter referred to as the first crack). After the passage of the scribing wheel, sometimes seconds later, the first crack is repropagated with a smooth surface (the second crack). The second crack propagates to 90% or more of the glass thickness under suitable scribing conditions, facilitating the breaking process. The mechanism of secondary crack propagation has not been sufficiently explained in previous studies. Therefore, this study used analytical and experimental methods to examine stress distribution and crack propagation behavior during wheel scribing. Finite element analysis suggests that the increase in the stress intensity factor contributing to the propagation of the second crack was due to not only the crack opening force but also the bottom deformation of the glass specimen. An analytical model accounting for the bottom deformation can simulate the characteristic behavior, such as rapid deepening when the scribing load exceeds a specific threshold value, of the second crack. This study indicates that the elastoplastic deformation caused by wheel contact induces the deformation of the entire specimen, and the state of the bottom constraints is important for controlling the second crack.

ガラスへの機能付与の一例として，固体イオン交換法を利用したガラス内銀析出物の形成があり，工業応用に向けて銀析出物形状の制御手法が検討されている．本研究では，レーザでの局所加熱を用いた銀析出物形状の制御を試行した．その結果，レーザ加熱部で選択的に銀析出が進行し，析出方向や太さはレーザ走査方向・スポット径により制御可能だとわかった．さらに，環境温度を下げたときレーザ加熱部以外の不要な析出が抑制できた．

固体イオン交換法によって銀イオン添加された試料に対し，電圧を印加することでガラス内に銀を析出させることができる．本手法は，ガラス内部に微細な導電路を形成する技術として期待されているが，析出物の形状制御手法が確立されていない．ここで，銀析出はき裂の生成をともなって進行することが確認されている．そこで本研究では，ホイール操作，レーザ照射を用いたき裂作成による析出物の誘導を行い，その原因を考察した．

<p>The authors have reported the laser-induced metal sphere migration in the glass. The metal sphere migrated toward the light source along the optical axis. In this paper, we describe the metal sphere separation by two laser beam illumination from the opposite direction. A stainless-steel sphere in borosilicate glass was heated by two continuous-wave green laser illumination. The laser beam diameter influenced the separation result. One metal sphere was separated to two spheres, when the beam diameter was 60 and 80 µm. When the beam diameter was 100 µm, the one metal sphere was not separated and maintained the shape and migrated toward one direction. When the beam diameter was 20 and 40 µm, laser illumination separate two small sphere from the metal sphere and one metal sphere was left. Hence the one metal sphere separated to three metal spheres. In-situ observation with a high-speed camera and numeral temperature calculation clarified the separation process. Finally, the size control of the metal sphere was demonstrated by changing the beam diameter.</p>

The authors reported that laser illumination to a metal sphere in glass migrated the metal sphere toward the light source. The migration was caused by interfacial tension gradient. In this presentation, we demonstrate the metal sphere separation by the two laser beam illumination from opposite direction. The metal sphere separation was not explained by the interfacial gradient and suggested the existence of pulling force to the light source side.

<p>端面に金属箔を密着させたガラスへ，反対面からレーザを照射すると，金属球がガラス内部へ導入される．導入効率の向上，直径の制御を目的に，新たな導入手法の提案およびスポット径，出力，スキャン速度を変数とした導入現象の観察を行った．その結果，スポット径の増大により，金属球の直径は12μm～65μmで単調増加した．また，出力の増大により，金属球の直径は減少した．適切なスキャン速度は，導入効率を向上させた．</p>

<p>Turning with suppressing thrust force has been proposed as a method of processing a micro-shaft. Advantages of thrust force free cutting have been demonstrated by turning micro-shaft (diameter: ~0.05 mm). Although the feed rate is a small value in the previous research, the processing efficiency has not been discussed because the processed shaft is small. If the long shaft is machined, it is indispensable to increase the feed rate to improve the machining efficiency. Therefore, in this research, we confirmed whether the suppression of thrust force was possible with high feed rate to expand the application range of thrust force suppression turning. The condition of suppressing thrust force by turning the long shaft of the medium diameter (~1 mm) was chosen, and the range of the small deformation by suppressing thrust force was clarified. It was also found that deflection due to principal cutting force also caused dimensional error even when thrust force was suppressed.</p>