中本 剛

This research work deals with the methods for manufacturing high aspect ratio micro mechanical parts by using UV photopolymer. In the first method, polymer structures are produced using a mask-based method. And the second is a direct focused UV laser irradiated portion solidified and it becomes a polymer structure. At first, the solidified shape of the polymer is in each method and the examined conditions to are verified. Next, the comparison methods are made. At last, examples that have been produced using described are shown.

This work concerns the development of a manufacturing technique for three-dimensional micromechanical parts. The micromechanical parts or micromolds are made by writing with a focused UV laser beam on the surface of a liquid photopolymer. At this time the irradiated portion of the liquid photopolymer becomes solid. Three- dimensional solidified polymer structures are then obtained by stacking the two- dimensional polymer structures. In this paper we theoretically examine the effect of absorption of light in a photopolylmer and exposure factors such as beam power and writing speed on the shape of the solidified polymer. The optimum conditions for three-dimensional micromechanical parts are also determined. Using these conditions, three-dimensional micropolymer structures are formed. The shapes obtained by stacking two-dimensional polymer structures are also examined.

SiC whisker reinforced plastics severely abrade the surface of contact materials. The wear characteristics of SiC whisker reinforced plastics and contact materials are investigated in this study. It was clarified that the wear of hardened die steel is minimized by adding graphite to the SiC whisker composite and aligning the whisker parallel to the contact surface, and maximized by aligning the whisker normal to the contact surface and applying oil lubricants. Furthermore, the wear of a SiC whisker composite is minimized by aligning the whisker normal to the contact surface and applying oil lubricants. By applying the condition of maximum wear of hardened die steel and minimum wear of a SiC whisker composite to the surface finishing process, a very fine surface finish with surface roughness of 2nmRa was 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 tool wear were investigated. The tool with fine grains exhibited higher wear rates. The greatest tool wear occurred with the composite having longitudinal alignment of whiskers. The cutting processes of various orientations of whiskers were observed by SEM at low speed. Moreover, models were proposed for cutting the SiC whisker-plastic composite and for the wear of sintered diamond tools.

The wear of a polycrystalline diamond tool in the cutting of a SiC grain-reinforced plastic composite is investigated. The effects of grain sizes of SiC in the composite and the diamond of the tool were concerned. The cutting experiments showed that higher wear of the tool occurs in cutting of the composite with larger SiC grains; the coarse-grained tool exhibits a higher wear resistance than the corresponding fine-grained one for all composites. Moreover, tool wear is increased drastically when the SiC grains are larger than the tool grains. On the other hand, a wear model, called the "tear-off model", was proposed to explain the wear mechanism of polycrystalline diamond tools in cutting the SiC-plastic composite. The model illustrated that the greater wear of the tool with the larger SiC grains call be attributed to the iscrease in debonding force of a SiC grain. Finally, an empirical relation, introduced as a fatigue-like curve, between the maximum stress on the tool grains and the number of stress cycles was established to describe the generalized relationship between the SiC grain size in the composite and the flank wear of the tool, taking into consideration the SiC volume ratio, SiC size and tool grain size.

This work deals with the development of a manufacturing technique for micromechanical parts. The micromechanical parts or micromolds are made by writing with a focused UV laser beam on the surface of a liquid photopolymer layer. The irradiated liquid polymer is then developed to produce a solidified micromechanical part or micromold. This paper theoretically examines the effect of physical parameters such as wavelength of the laser beam, focal length of the lens and writing speed on the shapes of the solidified polymer. The optimum conditions for high-aspect-ratio (height/width) micromechanical parts are also examined. Using a focused beam, high-aspect-ratio polymer structures are formed.

This research work deals with the development of a simple and practical method for manufacturing metallic micromachine parts on the order of 0.01-1.0 mm in size. In this method, an ultraviolet laser beam is irradiated onto the surface of a liquid photopolymer material through a mask. The irradiated pattern is then developed to produce a solidified photopolymer mold. Finally, the metallic part is made by an electroforming process. This paper deals with the first process, the making of the photopolymer mold. At first, the accuracy of the mold is estimated by applying the theories of diffraction and absorption of light. Next, the accuracy is examined experimentally. The results show an accuracy of +/- 1 mum can be obtained when a proximity transfer of 10 mum between the mask and the photopolymer surface is used. By stacking thin films, thick and high aspect ratio molds with a reasonably high accuracy are made.

This research work deals with the development of a simple and practical method for manufacturing metallic micromachine parts on the order of 0.01-1.0 mm in size. In this method, an ultraviolet laser beam is irradiated onto the surface of a liquid photopolymer material through a mask. The irradiated pattern is then developed to produce a solidified photopolymer mold. Finally, the metallic part is made by an electroforming process. This paper deals with the first process, the making of the photopolymer mold. At first, the accuracy of the mold is estimated by applying the theories of diffraction and absorption of light. Next, the accuracy is examined experimentally. The results show an accuracy of ± 1 μm can be obtained when a proximity transfer of 10 μm between the mask and the photopolymer surface is used. By stacking thin films, thick and high aspect ratio molds with a reasonably high accuracy are made. © 1994 by ASME.

Composite-type alloyed steel powder has drawn great attention in recent years in forming high-strength sintered metal. The powder consists of iron and additions of nickel and molybdenum which adhere to the surface of the iron particles. This type of sintered alloy steel causes excessive wear of tool during cutting. The purpose of this study is to improve the machinability of the sintered alloy steel by adding nonmetallic materials. Experiments show that the addition of 3% glass to the sintered alloy steel increases tool life by 100 times. In order to clarify the mechanisms of the increase of tool life, the worn face of the cutting tool is examined using an electron probe microanalyzer (EPMA). The analysis shows that the glass additive acts as a protective film and lubricant during cutting with silicon nitride and tungsten carbide tools, respectively.

This work deals with the development of a manufacturing technique for high-aspect-ratio (height/width) micromechanical parts. The micromechanical parts or micromolds are made by writing with a UV laser beam on the surface of a liquid photopolymer layer. The author examine the shapes of the solidified polymer that can be obtained by writing using several shapes of beams along typical contours. The examination is done both theoretically and experimentally. The results show that a beam with a uniform intensity has a higher resolution than a gaussian beam in obtaining a determined solidified width and vertical sidewall along the thickness of the polymer layer. By using a beam with uniform intensity, high-aspect-ratio polymer microstructures are made.

This paper deals with the lubricating action of nonmetallic inclusions in metal cutting. The purpose of this study is to find the most effective inclusions for metal cutting, and to develop free machining sintered metals including nonmetallic materials. The most effective additives are glass, boron nitride, and talc. By the addition of 3 percent glass to the iron, tool life could be increased 60 times.

This paper deals with the lubricating action of nonmetallic inclusions in metal cutting. The purpose of this study is to find the most effective inclusions for metal cutting, and to develop free machining sintered metals including nonmetallic materials. The most effective additives are glass, boron nitride, and talc. By the addition of 3 percent glass to the iron, tool life could be increased 60 times. © 1993 ASME.

This research work deals with the development of a simple and practical manufacturing technique for metallic micro structural parts in the order of 0.01-1mm in size. In this technique, an ultra-violet laser beam is irradiated into a liquid photopolymer material through a mask. The irradiated pattern is then developed to obtain the solid mold. The metallic part is then made by electroforming process. This paper deals with the first process that is making a photopolymer mold. At first the accuracy of the mold is estimated by applying diffraction and absorption theories of light. Next the accuracy is examined experimentally. The results show an accuracy of ±1μm can be obtained when the distance between mask and photopolymer layer is 10μm. By using the stacking of thin films, precise mold with deep straight Walls are made.

Mixtures of ferrous metal powders and non-metal additives are sintered and the sintered materials are cut. Then, the progress of tool wear during cutting is examined, and the most effective additives for prolonging tool lift are found. The conclusions obtained in the experiment are as follows : (1) The most effective additives are glass, talc and boron nitride. (2) By the addition of a 3% glass to the ferrous material, tool life has been increased by an about factor of sixty. (3) By the addition of a glass and talc mixture to the ferrous material, tool life is prolonged still more.

Mixtures of stainless steel powders and non-metal additives were sintered and those materials were cut, then, the progress of tool wear in cutting were examined. The most effective additives to prolong tool life were found. The conclusions obtained in the experiment are as follows. (1) The most effective additive was boron nitride. (2) The addition of a few volume percent of boron nitride to stainless steel made the tool life a hundred times longer than in stainless steel without additives. (3) By addition of a boron nitride and glass mixture to stainless steel, tool life was prolonged still more.

It is well known that inclusions in the workpiece have great influence on machinability. At the first stage, the lubricating ability of various non-metal materials was tested at an elevated temperature (700〜800℃). At the second state, a mixture of ferrous metal powders and non-metal additives was sintered, and a cutting test of these sintered materials was done. The coefficient of frictions at the tool-chip interface in cutting were examined, and the most effective additives were found. The conclusions obtained in this experiment are as follows : (1) The coefficients of friction at the tool-chip interface are able to reduce effectively by adding non-metal materials as an inclusion. (2) It is estimated that the most effective additives are lithium oxide, boron nitride, glass and tellurium oxide. Glass and boron nitride are the most prospective materials for improving machinability.

Mixtures of ferrous metal powders (pure iron, austenitic stainless steel, ferritic stainless steel) and non-metal additives (glass, talc, boron nitride) are sintered and those materials are cut. Then, the progress of tool wear during cutting is examined, and the differences of tool life between the sintered materials are examined. Next, in order to clarify the reason why tool wear decreases with the addition of non-metal materials, the relief face after cutting is examined with an Electron Probe Microanalyzer. The conclusions obtained are as follows : (1) Tool life is prolonged by the action of additives in pure iron and austenitic stainless steel, but it is not prolonged in ferritic stainless steel. (2) Glass in the sintered metal acts as a lubricant on the relief face.