中本 剛

波長変換に使用されるKDP結晶は,脆性材料であり,加工には多大な費用と手間を要する.本研究では,飽和溶液中で,KDP結晶の稜線に沿ってレーザビーム走査することによって,結晶面を研磨した.この加工による結晶面の性状を検討した.

Potassium dihydrogen phosphate (KDP) is a non-linear optical and water-soluble crystal. However, since KDP is brittle material, it takes a large cost to obtain the surface roughness required in generating harmonics. Therefore, a new polishing method using YAG laser beam is developed and verified the method by experiments in our research work. The method developed in this paper is as follows. A YAG laser beam is focused at an edge of an end face of a single crystal in a saturated solution. The laser beam is scanned along the edge of the end surface. It is possible to polish the scanned surface by the solution of the crystal and the other portions are not removed in a saturated solution. In this paper, the surface of the crystal polished by our laser beam scanning method was compared with that polished by sandpapers. The surface polished by laser beam scanning is smoother than that polished by sandpapers when the both surface roughness were same. The crystallinity of both crystals after polishing were same degree by X-ray diffraction analysis. The second harmonic generation were performed using KDP crystals before polishing, after laser beam polishing and after sandpaper polishing. The intensity of the light from the crystal by the laser beam polishing was the best of these three crystals.

The purpose of this research work is to fabricate small pipes consisting of boron carbide. The characteristics of boron carbide are hard and anti-corrosion. However, it is difficult to sinter the material and to obtain small pipes. Therefore, a new method is developed to fabricate pipes of boron carbide in this paper. At first, graphite powder is mixed with boron powder. And the surface of mixed powder is irradiated by a laser beam. And then, the powder is evaporated at the central portion of the laser beam. Boron carbide is produced around the central portion by the chemical reaction between the graphite powder and boron powder. Then, a small pipe consisting of boron carbide is obtained. The outer, inner diameter and length of the pipes are measured for different irradiating conditions of laser beam. The boron carbide is detected by XRD in the pipes. It is deduced that the concentration of boron carbide at the inner surface of the pipes is more than that at the other portions. Connected two or three pipes are fabricated by this method.

サファイアは高温では二酸化ケイ素と反応して複酸化物を形成する．この反応を利用してサファイアの加工を行う．二酸化ケイ素を多く含む材料としてガラスを選定し，これをサファイアで切削する．このときのサファイアの摩耗をサファイアへの加工として，加工条件が加工面や加工量へ及ぼす影響について検討する．その結果，良好な加工面は，低切削速度では水雰囲気中で，高切削速度では大気中で得られることがわかった．

サファイアは化学的に安定であるが，高温高圧下では酸化ケイ素や酸化鉄と化学反応し，サファイアが損耗することが知られている．本研究では，酸化ケイ素を含む材料としてガラスを，酸化鉄の元となる材料として鋼を選択し，これらをサファイアで切削加工した．このときのサファイアの摩耗をサファイアに対する加工として，加工雰囲気や加工条件が加工に及ぼす影響を調べた．

本研究では，鉄粉中にダイヤモンドを入れ，鉄粉表面をYAGレーザで局所的に加熱することによって，ダイヤモンドの除去加工を行った．まず，鉄粉と比較するためにアルミニウム粉末中および大気中でも実験を行い，鉄粉中でダイヤモンドが加工され，アルミニウム粉末中などでは加工されないことを確証した．つぎに，鉄粉の量や，レーザビームの照射時間，レーザビームのパワーなどの加工条件と除去量について実験を行った．

The purpose of this research is to produce microparts reinforced with unidirectional whiskers using laser stereolithography. Electrically conductive whiskers are added to a liquid photopolymer and an electric field is applied to the liquid photopolymer, which aligns the axes of the whiskers along the direction of the electric field. Then, the photopolymer is solidified with UV laser irradiation in a shape that is adjustable. When the electric field is applied, the whiskers are acted on by the moment that aligns them along the electric field in the liquid photopolymer. The liquid photopolymer does not begin to flow until the shear stress on the surface of the whisker reaches the value of the yield shear stress of the photopolymer. This characteristic is denoted as the Bingham property. Therefore, the whiskers do not rotate until the electric field is lower than the threshold value by means of the Bingham property. The Bingham property is measured and the values of the electric field required to rotate the whiskers are examined both theoretically and experimentally in this paper. Using the above results, solidified polymer structures containing unidirectional whiskers are fabricated. © 2013 by JSME.

This paper deals with development of a titanium boride grinding wheel. At first, a desired shape is made of titanium. Next, boron powder is spread on a surface of the titanium. The surface is scanned by a laser beam, and then titanium boride is produced on the surface of the titanium by the chemical reaction between the boron powder and the titanium. The produced titanium boride is used as a grinding wheel. Titanium substrates of plate shape are used in this paper for the experiments of producing titanium boride. The surface layers of the substrates are examined by an X-ray diffraction and titanium boride is detected in the layers. The cross sections of the layers are examined by an EPMA and EDS. Titanium boride is produced at the bottom of the groove those are generated by the laser scanning. Grinding experiments are performed using these grinding wheels. The results show that the sintered layer can be used for grinding of hardened die steel. The grinding wheel with small scanning interval of a laser beam can remove work material better and has small wear.

The purpose of this research is to produce micro parts reinforced by unidirectional short fibers using laser stereolithography. Ferromagnetic short fibers are added to a liquid photopolymer and a magnetic field is then applied to the liquid photopolymer, aligning the axes of the short fibers along the magnetic field direction. Then, the photopolymer is solidified by UV laser irradiation in a desired shape. Solidified photopolymers containing the unidirectional short fibers are layered until the desired height is obtained. The surfaces of the solidified layers are observed and the possibility of a reinforcing effect between the layers is examined.

The purpose of this research work is to produce micro part reinforced by unidirectional whisker in laser photolithography. Electrically conductive whiskers are added to liquid photopolymer. By applying electric field to this mixture, the axes of the whiskers are aligned along the direction of the electric field. Then, the photopolymer is solidified by an irradiation of UV laser in the desired shape. When the electric field is applied, rotating moment aligned along the electric field act the whiskers in the liquid polymer. However, when the value of electric field is small, the rotating moment becomes small. Therefore, the whiskers do not rotate and are not aligned along the electric field because the liquid polymer has the bingham property. The bingham property is measured and the value of electric field to rotate the whisker is examined both theoretically and experimentally in this paper. Using the above results, solidified polymer structures with micro size reinforced by unidirectional whisker are produced by this method.

本研究は発光ダイオードを光源に用いた小型マイクロ光造形装置の製作を目的としている．まず発光ダイオードから射出される光の強度分布を実験により求めた．次にこの光をレンズで平行光とし，さらに集光して紫外線硬化樹脂上に照射した．このようにして発光ダイオードによる樹脂硬化の特性を調べ，マイクロサイズの造形が可能となるレンズの配置を決定した．最後に装置を製作し，その装置でマイクロ構造物を造形した.

本研究では所望の形状と長さを有する繊維を製作し，その繊維によって強化した部品を製作することを目的としている．繊維は，鉄粉末上で設定した経路の沿ってYAGレーザビームを描画し，鉄粉末を部分的に溶融固化させることで得た．レーザの照射条件や粉末の粒径が繊維の製作に及ぼす影響を調べ，幅0.4mmで繊維を製作することが可能となった．さらに，光造形法で製作した部品を，この繊維で強化した.

サファイアでガラスを切削すると，切削点でサファイアとガラスが反応し，サファイアが摩耗する．本報告では，この現象を利用した加工の機構を検討する．切屑のEPMA分析より，サファイアとガラスが反応していると推定された．そこで，反応に基づく加工進展の理論モデルを構築して加工量を計算した．この結果は実験値と一致した．さらに，サファイアの結晶面方位による塑性すべりの生じやすさが，加工量の差に影響すると考えられた．

The purpose of this research work is to produce micro part reinforced by unidirectional short fibers by laser photolithography. Ferromagnetic short fibers are added to liquid photopolymer. By applying magnetic field to this mixture, the axes of the short fibers are aligned along the direction of the magnetic field. Then, the photopolymer is solidified by the irradiation of UV laser in the desired shape. The apparatus for applying the magnetic field is composed of four electromagnets in horizontal directions and one in vertical direction. The magnitude and direction of the magnetic field generated by these electromagnets can be changed. The degree of the alignment of the short fibers is examined using this apparatus. Several examples of micro structure reinforced by unidirectional short fibers are produced by this method.

This paper deals with development of a new method for producing profile grinding wheel. At first, the desired shape is made of metal that is machined easily. Next, powder material is spread on a surface of the metal. And the surface is scanned by a laser beam and then a ceramic layer is produced on the surface of the metal by the chemical reaction between the powder material and metal material. The produced ceramic layer is used as grinding wheel. The powder material is boron and the metal material is titanium in this experiment. The components of the layer are examined by X-ray diffraction and titanium boride is detected in the layer. Grinding experiment is performed using this grinding wheel. The results shows that the ceramic layer can be used to grind hardened die steel.

Diamond has become very important material for industry because the mechanical, thermal, optical and electrical characteristics. However, the machining of diamond is difficult for its high hardness. By the way, when cutting process is performed to ferrous material by a diamond tool, it is well known that the diamond tool will be worn severely. By utilizing of the tool wear, authors machined a diamond during cutting process of carbon steel. The purpose of this paper is to investigate micro machining of a diamond by this method.

Diamond is the hardest material; therefore, it is used as tools for ultra-precision machining. Recently, it is expected to apply diamond for molds of ultrasonic machining. However, when a diamond is used as a product, it must be shaped into the arbitrary shape. In order to get a bulk pattern of diamond, usually polishing a diamond by diamond-powder is done extensively, but this method is costly and takes long processing time. This research is an investigation of precision machining for a single crystal diamond by ferrous material using cutting process, in order to get the diamond I into bulk and three-dimensional shapes. It is found that ferrous material can remove and shape diamond, even though diamond is much more harder than ferrous material. The external surface of ferrous material is transferred to the diamond surface during the cutting process. This machining method is achieved by utilization of diamond graphitization and tool wear during the cutting process. The removal rate has been measured experimentally, and the removal rate is calculated on based graphitization. The calculated value of removal rate matches closely the experimental removal rate. The machining temperature is effective on machined depth, since the graphitizing process is affected by the temperature degree. Several shapes of diamond are produced by present machining method, such as a truncated pyramid, lattice grooves shape and several surfaces shape of diamond, where the machining time for each sample is less than one minute.

Development a machining method for single crystal diamonds has been investigated, as a result of the intense need of 3-D shapes of diamond. This processing method is achieved through utilization of diamond graphitization and tool wear of diamond during the cutting process of carbon steel. A three-dimensional shape of diamond has been successfully obtained by this machining method. In this study, a comparison has conducted among the present cutting method and other processing methods. At first, the present method is compared with a YAG laser machining; the diamond surface after machining by present method is much better than that by YAG laser machining method. Next, the present method is compared with other methods that utilize the affinity between diamond and ferrous material, using only heating or rubbing. The removal rate of diamond in cutting technique of this research is considerably higher and efficient than other methods. Some samples of the machined diamond by present method are shown in the end of this paper.

This study deals with the development of a method to machine a diamond. This method utilizes tool wear of a diamond during cutting process of carbon steel. A three-dimensional shape of diamond has been successfully obtained by the present method in less than one minute. The study in this paper is concerned with the machining rate of a diamond when the crystallographic orientation of a diamond is (1,0,0),(1,1,0) and (1,1,1). The machining rate is best in the case of (1,1,0) plane, next in the case of (1,0,0) plane, and less in the case of (1,1,1) plane. The removal rate of a diamond by the present method is much larger than that by friction between diamond and carbon steel. Some samples of machined diamond by the present method are shown in the end of this paper.

This paper deals with the development of simple and practical methods for fabrication of micro parts using laser induced photopolymerization. Mask pattern transfer method is used for high aspect ratio (height/width) parts. Focused laser beam writing method is used for both high aspect ratio parts and three dimensional parts. The accuracy of the solidified polymer when using these methods is examined. Various shapes of micro polymer structures are produced using these methods.

When diamond is used as a product, it should be machined into a required shape. In order to get bulk shape pattern of diamond, usually polishing diamond with diamond-powder is done extensively, but this method is costly and takes processing time. To make three-dimensional shape of diamond, polishing process must be performed many times for several surfaces. For example, to produce micro grooving tool, diamond must be shaped into slender form before polishing. In order to make a mold for the nozzle channel of ink-jet printer, diamond must be shaped into a narrow grooves shape. The previous examples emphasize the importance and necessity of shaping diamond into an arbitrary shape in industrial area. This research is an experimental investigation of micro machining of diamond by ferrous material, in order to get the diamond into an arbitrary shape, though utilization of diamond graphitization and tool wear during the cutting process. It is found that ferrous material can polish and shape single crystal diamond, even though diamond is much more harder than ferrous material. For comparison machining by other materials has been conducted. The removal rate has been measured, the surface roughness of machined diamond is comparable with the surface roughness of new commercial cutting diamond, and better than laser manufacturing surface roughness.

The shrinkage and irradiated energy distribution cause manufacturing errors in laser photolithography for producing micro parts. The manufacturing accuracy when producing micro parts is calculated in this paper. The micro polymer part is reinforced by unidirectional whiskers in order to improve the manufacturing accuracy. The shrinkage ratio is decreased by the addition of unidirectional whiskers.

This research work deals with the method for manufacturing unidirectional whisker reinforced micro part by laser photolithography. In this method, by applying direct current (DC) to mixture of photopolymer and whisker, the axis of the whisker is aligned along the direction of the electric field. The polymer is solidified by UV laser beam writing during applying the direct current. This paper examines the alignment of the by this method.

Composite-type alloyed steel powder has drawn great attention in recent years due to the rapid increase of high strength materials. A typical powder consisting of iron with nickel and molybdenum as an additive which adheres to the surface of iron particles is used. This type of sintered alloyed steel causes excessive tool wear. The purpose of this study is to improve the machinability of the sintered alloyed steel by adding nonmetallic materials. Experiments show that the addition of 3% glass to the sintered alloyed steel increases the tool life 100 times. In order to clarify the mechanisms of the increase of tool life, the worn face of the cutting tool is examined by an Electron Probe Microanalyzer (EPMA). The analysis shows that the glass additive acts as a protective film and lubricant when cutting with silicon nitride and tungsten carbide tools, respectively.

This study concerns the wear of sintered diamond tools in the cutting of SiC-particle-epoxy composites. The effects of the SiC particle size, volume ratio in the composite and diamond grain size of the cutting tool on tool wear were investigated. The experimental work has shown that a coarse-grained diamond tool exhibits higher wear resistance than a corresponding fine-grained tool. Greater tool wear was obtained in cutting the composites that had coarser particles and a higher volume ratio of SiC. Moreover, it was found that the tool wear increases drastically when the SiC particles are larger than the tool grains. A wear model of the tool was proposed, in which the tool is worn mainly by the 'tear-off' mechanism of the diamond grains. This model could explain the experimental results by comparing the pushing force of an SiC particle with the tear-off resistance of the diamond grains of the tool. Finally, a fatigue-like empirical curve was established. This curve can be used to predict the wear of the tool during cutting of the composite. (C) 1997 Elsevier Science S.A.

This paper studies the wear characteristics of hardened die steel and SiC whisker-plastic composite when they slide against each other. Moreover, a new application of the composite is introduced. It has been demonstrated that the wear of hardened die steel can be minimized by the addition of graphite powder to the composite and aligning whiskers parallel to the contact surface. Alternatively, the wear can be maximized by aligning whiskers normal to the contact surface and applying oil lubrication. The conditions that maximize the wear of hardened die steel were applied to the surface finishing process. By this method, an ultra-fine finish with a surface roughness of R(a) = 2 nm could be obtained.

This study concerns the cutting process of unidirectional SiC whisker-reinforced plastic composite. The effects of the grain size of the polycrystalline diamond tool and the SiC whisker orientation on the tool wear were investigated. The tool with fine grain size exhibited higher wear rates. The greatest tool wear was with the composite having longitudinal, alignment of whiskers. The cutting processes of various orientations of whiskers were observed by scanning electron microscopy at low speed using a specially designed device. Moreover, models were proposed for cutting the SiC whisker-plastic composite and for wear of sintered diamond tools.

This research work deals with the development of a simple and practical method for manufacturing high aspect ratio micro mechanical parts using three methods. The first method is mask-based method in which an image is transferred to a liquid photopolymer by irradiating a UV laser through a patterned mask. The irradiated portion of the photopolymer is then solidified and it becomes a high aspect ratio polymer structure. In the second and third methods, high aspect ratio polymer structures are produced using a shaped UV laser beam writing and a focused UV laser beam writing, respectively. The accuracy of the solidified polymer when using these methods is examined. Various shapes of micro polymer structures are produced using these methods.

This research deals with the development of a simple and practical method for manufacturing high-aspect-ratio (height/width) micro-parts and three-dimensional micro-parts. The desired product shape is obtained by writing along the contour of the product on the surface of a liquid photopolymer using a focused UV laser beam. The written pattern then becomes solid so as to produce a solidified polymer mold or structure. This paper examines the effect of physical parameters such as wavelength of laser beam, focal length of lens, absorption coefficient and writing speed on the shapes of the solidified polymer. The examination is done theoretically, and the optimum conditions to produce high-aspect-ratio micro-parts and three-dimensional micro-parts are also verified. Using these conditions, various microstructures are produced.

This research work deals with the development of simple and practical methods for manufacturing micro mechanical parts using photopolymer. The first one is the mask-based method. An ultraviolet (UV) laser beam is irradiated onto the surface of a liquid photopolymer material through a mask. The irradiated portion of the photopolymer is thereby solidified, and it develops a high aspect ratio (height/width) polymer structure. In the second method, high aspect ratio polymer structures and stacked three dimensional polymer structures are made by writing with a ultraviolet laser beam on the surface of a liquid photopolymer along the contour of products. First, this paper theoretically examines the accuracy of the solidified polymer and the optimum conditions for high aspect ratio structures and stacked three dimensional structures when using these methods. Next, the solidified shape and the accuracy of the products are examined experimentally. Lastly, these methods are utilized to produce micro mechanical parts of various shapes.