氏名　上段　一樹
学位の種類　博士（工学）
学位記番号　博甲第269号
学位授与の日付　平成15年3月25日
学位論文題目　Evaluation of Abrasive-Grain Protrusion Heights in Grinding Stones and Low Specific-Grinding-Energy Machining　（砥石の砥粒突き出し高さ評価と低比研削エネルギ機械加工）
論文審査委員
　主査　教授　石崎　幸三
　副査　教授　秋山　伸幸
　副査　教授　高田　孝次
　副査　助教授　田辺　郁男
　副査　助教授　南口　誠
　副査　神奈川県産業技術センタ－研究主幹　近藤　祥人

• 論文目次
• 論文要旨

［平成14（2002）年度博士論文題名一覧］ ［博士論文題名一覧］に戻る．

CONTENTS

Abstract　p.I
Contenets　p.II
Nomenclature　p.III

Chapter1　General Introduction　p.1
1-1 Back ground of the study　p.2
1-2 Surface topography of grinding stone affecting on ground surface topography　p.4
1-3 Matrix material for grinding　wheels　p.7
1-4 Grinding-wheel dressing-technique　p.9
1-5 Variety of dressing methods　p.10
1-6 Laser interractions with material　p.14
1-7 Objectives of the present study　p.22

Chapter2　Laser Dressing of Cast-Iron Matrix Diamond Grinding Stones　p.25
2-1 Introduction　p.25
2-2 The removal of cast-iron by kaser irradiation　p.25
　2-2-1　Experimental　p.25
　2-2-2　Results and discussion　p.28
2-3 Oxidation of cast-iron during laser treatment　p.46
2.4 Summary　p.50

Chapter3　The Enhancement of Adhesion Strength between Diamond Grains　p.51
　and Iron by Laser Irradiation
3-1 The reaction between diamond and iron with laser irradiation　p.51
　3-1-1 Experimental　p.51
　3-1-2 Results and discussion　p.54
3-2 The adhestion of iron on diamond surface with laser irradiation　p.62
　3-2-1 Experimental　p.62
　3-2-2 Results and discussion　p.63
3-3 Summary　p.66

Chapter4　The Estimation Method for an Abrasive-Grain Protrusion Height of　p.67
　Grinding Stone Surfaces
4-1 Problems in abrasive-gGrain protrusion height of measurement　p.67
4-2 The measurement method for the surface topography of grinding stones　p.69
　4-2-1 Grinding stone fabrication and grinding tests　p.69
　4-2-2 Surface topography analysis by confocal laser microscope　p.70
4-3 The surface characterization of a porous cast-iron matrix diamond grinding stone　p.72
　4-3-1 The analysis on surface topography of a mechannically dressed　p.72
　porous cast-iron matrix diamond griding stone
　4-3-2 The distinction of matrix material topography from entire surface topography　p.78
　of a grinding stone
4-4 Summary　p.83

Chapter5　Precision Grinding by Laser Dressed Grinding Stones　p.85
5-1 Effect of GS topography on grinding precision　p.85
5-2 Experimental　p.87
5-3 Results and discussion　p.90
　5-3-1 The surface topography of as-dressed surfaces　p.90
　5-3-2 The surface topography of post ground surfaces　p.98
　5-3-3 The relationship between the GS surface topography and the surface topography of a ground material　p.104
5-4 Summary　p.109

Chapter6　The Grindability of Laser Dreseed Grinding Stones　p.111
6-1 Specific grinding energy of a laser dressed grinding stone　p.111
6-2 Experimenntal　p.111
6-3 Results and discussion　p.112
6-4 Summary　p.124

Chapter7　Conclusion　p.125
7-1 Estimation of an average abrasive-grain prptruction height　p.125
7-2 Optiomization of laser dressing conditions　p.125
7-3 Effect of laser-dressed topography on grinding precision and specific grinding energy　p.126

7-4 Prospects　p.127
References　p.128
Appendixes　p.140
Acknowledgement　p.143
Publications and reserch activities　p.144

The present author proposes to achieve highly efficient grinding for ceramics　machining through this study.Grinding that is a sum of small cuttings by abrasive-grains is a major machining process for hard and brittle materials, such as advantage ceramics.　Abrasive-grains are usually three dimensionally distributed in a grinding tool and comprising a surface topography.　The surface topography of a　grinding tool e.g., a grinding stone, is the most essential function, which directly affects precision and efficiency of the process.　An abrasive-grain protrusion height defined as the distance between a cutting edge of an abrasive-grain and the matrix surface is
one of the important topographical parameters.
　The present study is specifically focused upon development of a surface conditioning method for diamond grinding stones by laser, and simultaneously, to establish a quantitative estimation method for an abrasive-grain protrusion height in order to　control the surface topography on a grinding stone.　Through experiments and evaluations of laser dressing and grinding on a porous cast-iron matrix diamond　grinding stone, followings have been revealed.
　The presented estimation method gives a precise average abrasive-grain protrusion height from the surface topography of a grinding stone.　By a confocal laser-scanning microscope, which supplies three-dimensional information of an observed object, a　cutting edge density distribution and a surface section area （surface roughness） distribution
of a grinding stone are analyzed, and median values of these distributions　are statistically calculated.　Analysis of a grinding surface topography clearly reveals that a laser dressing is an effective surface conditioning method to achieve　abrasive-grain protrusions without any grain dislodgment and to keep an initial grain distribution of a processed grinding stone while it is impossible to avoid grain　dislodgment as well as to keep an initial grain distribution by a conventional mechanical method.　As a consequence, a laser dressed grinding stone forms higher number of ground grooves with more uniform distribution along depth on a ground material surface than a mechanically dressed grinding stone.　Thus, precise grinding is surely achieved by laser dressing.
　On a laser dressed surface, a cast-iron matrix is removed by evaporation or laser ablation and volume-contracted by melting and sintering.　At a fused layer, the matrix cast-iron is oxidized, which may keep the matrix brittle.
In addition, by laser　irradiation , cast-iron melts and adhered to a diamond surface with the chemical reaction to form Fe3C at an interlayer.　This carbide formation enhances adhesion strength between cast-iron and diamond grains. However, since molten cast-iron covers　diamond surfaces, diamonds may lose sharpness of cutting edges although the
damage　in a diamond structure is negligible under irradiation.
　The laser-dressed matrix shows a unique geometry due to heterogeneity of laser absorption on a porous matrix surface.
At the interface between cast-iron particles, higher energy will be absorbed by continuous repetition of absorption and reflection than the energy absorbed on a particle surface apart from the interface.　As a result,　cone shape particles are formed on the irradiated surface.　This topography eases deformation of a laser dressed matrix by grinding pressure and leads increment of grain protrusions.　Even though the initial grain protrusion height on an as-dressed surface is relatively smaller, a real protrusion height during grinding becomes larger than that of a mechanically dressed stone.　In fact, the removed volume rate for a laser dressed grinding stone continuously increases with applied grinding pressure at which matrix deforms and grain protrusion heights increase while the removed volume rate for a mechanically dressed stone becomes constant due to the matrix material interacting with a ground material and stopping grain penetrations.　At the same time, the grinding　force ratio for a laser dressed grinding store is kept at constant, but that for a mechanically dressed grinding stone decreases at a high pressure.　As a consequence, a laser dressed stone can achieve lower specific grinding energy than a mechanically dressed one, especially at the condition of a high grinding pressure.