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en: Polishing Performance of a Recycled Grinding Wheel Using Grinding Wheel Scraps for the Wet Polishing of Stainless-Steel Sheets

en: The surfaces of large austenitic stainless-steel sheets, which have side lengths of at least 1 m a sheet thickness of at least 6 mm, used for food tanks and sliding plates in seismic isolation devices, must be finished to a mirror surface. Polishing is performed to improve the surface quality of such sheets and dry machining is typically applied. The problems associated with dry machining are the exhaust heat of machining and treatment of chips. A transition to wet machining is required to solve these problems. In our laboratory, we have developed a wet polishing machine and researched the selection of grinding wheels to develop wet polishing technology for large stainless-steel sheets. In this study, to reduce tool cost and reuse resources, we attempted to manufacture a recycled grinding wheel using snippets of grinding wheel scraps. A polyvinyl alcohol (PVA) aqueous solution was used as the bonding agent for the recycled grinding wheel to reduce environmental load. To overcome the ease of dissolution of PVA in water, we attempted to improve the water resistance of the PVA aqueous solution by incorporating an organic titanium compound. This is one of our efforts to contribute to sustainable development goals. The results are summarized below. (1) A recycled grinding wheel was fabricated by kneading crushed pieces of grinding wheel scrap with a bonding agent. (2) The maintenance of the shape of the recycled grinding wheel was controlled by the concentration of the bonding agent. (3) The recycled grinding wheel with a PVA bonding agent was vulnerable to water. In contrast, the recycled grinding wheel to which the organic titanium compound was added exhibited improved water resistance. (4) The polishing of stainless-steel sheets using the plain PVA recycled wheel was relatively ineffective, but polishing using the recycled wheel with the titanium additive was comparable to polishing with a new grinding wheel.

ja: 食品タンクや免震装置のすべり板などに使用される一辺1m以上，板厚6mm以上の大型オーステナイト系ステンレス板は表面を鏡面に仕上げる必要がある．このようなシートの表面品質を改善するために研磨が行われ，通常は乾式機械加工が適用される．乾式加工の課題は加工時の排熱と切りくず処理である．これらの問題を解決するには，湿式加工への移行が必要である．本研究室では，大型ステンレス鋼板の湿式研磨技術を開発するため，湿式研磨機の開発と砥石の選定を検討した．本研究では，工具コストを削減し，資源を再利用するために砥石スクラップの断片を使用して再生砥石の製造を試みた．再生砥石の接着剤にはポリビニルアルコール(PVA)水溶液を使用し，環境負荷を低減した．PVAの水への溶けやすさを克服するため，有機チタン化合物を配合することでPVA水溶液の耐水性を向上させようとした．これは持続可能な開発目標に貢献するための私たちの取り組みの 1 つです．結果を以下に要約する．(1)砥石廃材の破砕片を接着剤で練り合わせて再生砥石を作製した．(2)再生砥石の形状維持は結合剤の濃度によって制御された．(3)PVA 結合剤を使用した再生砥石は水に弱かった．一方，有機チタン化合物を添加した再生砥石は耐水性が向上した．(4)PVA 再生砥石を使用したステンレス鋼の研磨は比較的効果がなかったが，有機チタンを添加した再生砥石を使用した研磨は通常の砥石での研磨に匹敵した．

en: International Journal of Automation Technology (IJAT)


en: Improved Chip Discharge in Drilling of Glass Plate Using Back Tapered Electroplated Diamond Tool

en: Previous studies of a through-hole drilling for hard and brittle materials using electroplated diamond tool devised by the authors have led to several challenges such as a restraint of crack size at the inlet and outside, a suppression of chip adhesion on the tool and an improvement of processing efficiency. In this paper, the devised tool was redesigned in order to restrain cracks of the inlet side as well as to improve the chip discharge. The new design of the tool featured a back taper which was expected to bring an effect of restraining crack size by preventing any interference between the tool cylindrical surface and the hole inner surface during drilling process. In addition, the chip can be discharged from the drilled hole through the back taper. Results of the experiment indicated that by providing the back tapered shape, the width of the inlet hole can be reduced slightly as the interference between the glass plate and the tool cylindrical surface was suppressed. Furthermore, the adhesion of chip on tool can be restrained by using the tool with large chip discharge space as the chip was easily discharged to the outside of the hole. Moreover, an abrupt change in thrust force was not detected, and the crack width was found in small size.

en: International Journal of Precision Engineering and Manufacturing


en: Investigation of Grinding Fluid for Prevention of Chip Adhesion in Miniature Drilling of Glass Plate Using Electroplated Diamond Tool

en: Key Engineering Materials

ja: Key Engineering Materials


en: Mechanical Properties and Cutting Performance of Electroless Ternary Ni-W-P Coated Cutting Tools

en: Jurnal Teknologi

ja: Jurnal Teknologi


en: Fundamental Study on Hole Fabrication inside a Hole by Means of Electrical Discharge Machining

ja: International Journal of Automation Technology (IJAT)


en: Development of electroplated diamond tool for fracture size minimization in miniature drilling of glass plate

ja: ガラス板への高品位通り穴加工を目的とした小径ダイヤモンド電着工具の開発

en: To minimize fracture size in through-hole drilling of glass plate, this paper examines drilling behavior of commercial tool shape, as well as the availability of a tool shape designed by the authors. The chipping size occurring at the hole edge is related to the form of tool end and the chip elimination efficiency. The designed tool, which is an electroplated diamond tool with a diameter of 1 mm, has a unique shape. The tool shape has a hemispherical tool end and a few straight planes. During drilling, the hole enlarges gradually due to the hemispherical shape of the tool end. The occurrence of chipping at the edge of the exit hole is reduced because the hemispherical shape can reduce the abrupt decrease in drilling force. That is, large chipping and cracking corresponding to the hole diameter can be suppressed. In addition, the straight planes play a role in eliminating chipping, and the adhesion of chips is suppressed. The results of this investigate indicate that the designed tool allows drilling of drilling cycle.

ja: 本論文は，ガラス板への小径通り穴加工において，穴縁周りの欠けを小さく抑える工具形状についての検討を行うとともに工具の開発を行った．穴縁に生じる欠けの大きさは工具先端の形状と切りくずの排出性能に関係した．得られた知見から，著者らは工具穿孔部が他に類を見ない形状を持つ小径ダイヤモンド電着工具を開発し，この工具の有効性を調査した．本工具の特長的な点は，工具先端部が半球状であることと穿孔部がストレート面をもつことである．工具先端部を半球形状にすることで，穴は徐々に繰り広げられるような加工となる．この形状により，加工抵抗の急激な変化は抑えられるため，欠けは小さくなった．すなわち，穴径に相当するほどの大きな欠けや割れは抑制できた．そして，ストレート面は切りくずを排出する役目を担い，切りくずの付着を抑制した．本工具1本のみを使用した通常のドリリングサイクルでの穴加工を可能とした

en: Journal of the Japan Society for Abrasive Technology

ja: 砥粒加工学会誌


en: Restraint of Thermal Crack on Rake Face of Cermet Tool in Intermittent Cutting


en: Relationship Between In-Plane Stress and Modal Shape of Disk

ja: 円板の面内応力と振動モード形状に関する研究

en: In this paper, we analytically considered the effects of the in-plane stress of the disk on the changes of modal shape. The purpose of this study is to confirm whether the modal shape changes according to the in-plane stress. The results make it clear that the in-plane stress changes the modal shape and its curvature. The curvature of the modal shape is proportional to the reciprocal number of the bending stiffness. Thus, it is confirmed that the in-plane stress serves to change the bending stiffness distributions on the disk. Moreover, the natural frequencies of the disk are evaluated by two energy methods in which the variations of modal shapes are considered or not. The difference in the natural frequencies from two energy methods shows the effect of the changes in the modal shape of the disk due to the small difference in the results of the energy methods (maximum difference of strain energy: 7.1%). Finally, the two energy methods are compared to investigate the effects on the natural frequencies with hammering test. The experimental results show the traditional energy method is allowed to evaluate the natural frequencies practically.

en: Transactions of The Japan Society of Mechanical Engineers, Series C

ja: 日本機械学会論文集(C編)


en: A Study on the Transverse Vibration of the High Speed Rotating Circular Saw and the Countermeasure

ja: 高速回転する丸鋸の振動とその対策に関する研究

en: In this paper, we considered a new tensioning method by the centrifugal stress on the base metal of rotating circular saw. First, the residual stress distribution on the base metal generated by roll tensioning and the centrifugal stress distribution was compared by calculation using a disk model (Φ305mm). As the results, it was confirmed that the tangential stress ςϑR by centrifugal force at outer of disk became larger than the residual stress ςϑP by roll tensioning when the rotational speed is higher than 7300 rpm. This rotational speed is larger than 1.4 times of the critical speed (resonance rotational speed) of disk. And it is concerned that the unstable vibration may be generated. Therefore, we investigated the behavior of the unstable vibration and established the countermeasure by the rotating experiment. As the results of the rotating experiment, we considered that the unstable vibration is the self-excited vibration as the negative damping caused by the effects of the high-speed airflow around the rotating disk. According to this consideration, we investigated the relationship of the damping coefficient of disk and the behavior of the unstable vibration. As the result, it is confirmed that the rotational speed of the unstable vibration occurred becomes higher with the increase of the damping coefficient of disk. It is confirmed that it is possible to suppress the unstable vibration of disk and provide the tensioning effect by centrifugal force of disk.

ja: 日本機械学会論文集(C編)


en: Through-Hole Drilling of Glass Plate Using Electroplated Diamond Tool

en: Applied Mechanics and Materials

ja: Applied Mechanics and Materials


en: Study on Applying Cavitation in Micro Drilling of Austenite Stainless Steel --- Control of Burr in Through Hole Drilling

en: International Journal of Automation Technology (IJAT)


en: Influence of Tapping Conditions and Tool Geometries on Tool Life in Tapping of Inconel 625®

en: Inconel 625® contained Ni 61%, Cr 21.5%, Mo 9% and so on is one of the nickel base super heat resistant alloys and is used for parts in food machine. The nickel base alloys are generally difficult-to-cut materials because of high thermal resistance, high work hardening, high chemical activity and low thermal conductivity. In tapping, furthermore, the tool failure such as chippings, cracks and tool fractures has been frequently observed owing to low rigidity of tool. This paper deals with the influence of surface treatment, tool geometry etc. on the cutting phenomena such as the tool failure, the cutting force and so on when tapping Inconel 625® using the high speed steel tool. The damage of oxidizing tool is slower than that of nitriding tool. The large thrust force in backward tapping causes rapid tool fractures. The smaller helix angle leads to the lower thrust force in backward tapping.

en: Key Engineering Materials


en: Drilling machinability of resin-less "green" composites reinforced by bamboo fiber

en: この論文では，穴あけ加工時における竹繊維グリーンコンポジットの被削性について述べる．グリーンコンポジット，竹および杉を鉄工用ドリル，木工用ドリルを使って穴あけ加工し，スラスト力，比切削抵抗，加工穴の性状，切りくず形状および工具摩耗によって被削性を検討した．レジンレス竹繊維強化グリーンコンポジットのスラスト力は，他の被削材に比べて大きく，切りくずは非常に長かった．鉄工用ドリルを用いて，切削速度15m/min，送り0.03mm/revで穴あけ加工を行うとレジンレス竹繊維強化グリーンコンポジットの加工穴に発生するバリやコバ崩れは小さかった．穴周りの欠陥を少なくするためには，グリーンコンポジットの単繊維を鋭い切れ刃で切削しなければならず，工具としてダイヤモンド電着工具の使用が考えられる．

en: WIT Transactions on the Built Environment


en: Flexural properties of all bamboo "green'' composites

en: 本論文は，竹の強度改善を目的としてマダケに対して種々の条件でホットプレス成形を行った結果をまとめたものである．評価すべき強度特性として，3点曲げ強度，曲げ弾性率，圧縮強度，アイゾット衝撃強度に注目した．その結果，曲げ強度，圧縮強度，衝撃強度はホットプレス成形温度の上昇につれて向上し，160℃でピーク値を示すことが分かった．さらに内部組織の調査から，維管束部と柔細胞部の圧縮変形により試料の高密度化が行われ，この密度向上に対応して各種強度特性が向上することが分かった．

ja: WIT Transactions on the Built Environment


en: Through Hole Drilling of Alumina Ceramic with Electroplated Diamond Tool (2nd Report) --- Effects of Oil Through and Mesh Size on Drilling Performance

ja: 小径ダイヤモンド電着工具によるアルミナセラミックへの通し穴加工(第2報) --- オイルスルー方式と粒度の効果

en: 直径1mmの通し穴加工において工具先端領域に付着する切りくずの除去および電着工具の安定性を上げるために，オイルスルー方式や粒度の影響を検討している．低速域の切りくずの付着を少なくし，工具寿命を長くするとともに穴直径の寸法精度を良くする．粒度が大きいほどスラスト力と欠け幅は小さくなる．

en: Journal of the Japan Society for Precision Engineering, Contributed Papers

ja: 精密工学会誌論文集


en: Slanting-hole drilling of glass plate using an electroplated diamond tool

ja: 小径ダイヤモンド電着工具によるガラス板への高品位斜め穴加工

en: The utility of slanting-hole drilling using an electroplated diamond tool of small-diameter devised by the authors was investigated. As with straight-hole drilling, a normal drilling cycle could be adopted with slanting-hole drilling because the unique shape of the tool increases chip discharge. In addition, the drilled hole showed a small degree of chipping without using an underlay board and/or ultrasonic wave instrument. The chipping width was influenced by the behavior of the axial component of the grinding force before completion of the drilling process.

ja: 著者らが考案した小径ダイヤモンド電着工具を用いて，ガラス板への斜め穴加工を行い，本工具の斜め穴加工への有用性を調査した．直穴加工時と同様に，本工具の特長的な形状により，切りくず排出のためのステップ送りを採用しなくとも切りくずの排出は良好であり，通常の一方向送りのドリリングサイクルでの穴加工は可能であった．また，座ぐりや捨て座，超音波援用装置などを用いなくとも，工具の食付き側および抜け側に生じる欠けは小さかった．工具抜け側の欠け幅は加工終了間際の軸方向成分の挙動に左右した．

en: Journal of the Japan Society for Abrasive Technology