Kozo Kishi

Nanotopography of ultraprecise ground surface of fine ceramics using atomic force microscope

Summary The nanometer-scale imaging of ultra-precise ground surface of Si 3 N 4 ceramics has been conducted with an atomic force microscope. An ultra-precise surface with a roughness of about 8 nm R max could be generated when fine grain diamond wheel with a grain size of =10.000 was used. The topography of the ultra-precise ground surface is affected by the protrusion of grain boundary phase out of Si 3 N 4 crystal surface as well as by the unevenness of grinding streaks. There is an infinite number of ultrafine projections with a height of less than 1.5 nm on the grinding streak surface. These ultrafine projections have slightly an anisotropic geometry in the shape and in the distribution.

The Newly Developed CBN Cutting Tool

The newly developed cutting tool, Sumiboron BN200, is made of a special ceramic which is heat resistant, wear resistant and has a lower affinity for a workpiece material. The following experimental results were obtained: 1) Grains of BN200 showed attritious wear in a wide range of cutting conditions. 2) The bonding material of BN 200 was removed to such an extent by formed chips that grains were projected. Abrasive wear was partly observed. 3) In dry cutting of ASTM4118 and wet cutting of ASTM 5046, the tool life of BN200 was found to be increased by respectively 3~5.7 times that of a conventional CBN cutting tool.

Analysis of Ductile Mode Ground Surface of Optical Glass by Atomic Force Microscopy

The microstructures of ductile mode ground surface of optical glass generated by using fine grained diamond wheels have been investigated with an atomic force microscope. The main results obtained in this paper are summarized as follows: (1) There is an infinite number of ultrafine projections with a height of less than 2.5 nm on the ductile mode ground surface. (2) These fine projections have slightly an anisotropic geometry in the shape. It seems that the anisotropy is closely related to the grinding mechanism. (3) A supersmooth mirror surface with a roughness of 7 ~ 10 nm R m a x can be obtained by using a very fine grain diamond wheel of grain size #10000. The height of ultrafine projections existed on these mirror surface is less than 1.5 nm, which is lower than that on the ductile mode ground surface generated by a diamond wheel with a grain size of #800.

Mirror finish grinding of β-sialon with fine grained diamond wheels

常圧焼結β-サイアロンの微粒ダイヤモンド砥石による平面研削実験を試み, 鏡面研削特性に及ぼす砥石粒度の影響を検討した結果, 粒度6/12μm以下の微粒ダイヤモンド砥石による研削では, 連続流れ型の切屑が生成され, 切屑及び仕上げ面の生成が塑性変形を主体とするメカニズムで行われていることが確かめられた. また粒度6/12μm以下の微粒ダイヤモンド砥石による研削では, 破砕面の非常に少ない平滑な鏡面が得られ, 例えば0.5/3μm砥石による研削では, 仕上げ面粗さ約0.03μm Rmaxの極めて平滑な鏡面が得られた. 研削抵抗二分力, 比研削エネルギーUe及び砥石-工作物接触面最高温度 (砥石研削点最高温度) θmは, 砥粒粒径の減少とともに増大する. また砥粒の平均粒径dが約20μm以下の範囲において, Ue及びθmはともに (-logd) にほぼ比例する.

Generation Behavior of Edge-Chipping of Polycrystalline Ferrites Having Different Fracture Modes in Slot Grinding.

Precise slot grinding experiments were conducted on two kinds of polycrystalline Mu-Zn ferrites, which showed intergranular and transgranular fracture, respectively, to investigate the influences on fracture mode of changes in size and shape of the edge-chipping. In the case of using fine grain, maximum chipping size of transgranular-fracture-type ferrite was smaller than that of the inter-granular fracture type ; however, in the case of using coarse grain, maximum chipping size was reversely to the case of using fine grain. This reversed phenomenon was explained based on the differences in fracture mode of the materials. The percentages of intergranular fracture of these materials were examined in detail by SEM observation. The transgranular fracture type was suitable for precise slot grinding using fine grain. On the other hand, the intergranular fracture type was suitable for normal slot grinding using coarse grain. As a result, new technology for reducing the edge chipping which controls the grain boundary strength using an additive was developed.

Formation of grinding streaks by a single diamond abrasive grain in ultra high speed grinding

To enlarge the basic knowledge concerning the ultra-high speed grinding process, the groove formation generated by a single abrasive diamond grain was investigated in a peripheral grinding wheel speed between 30 and 230m/s. The single grain cutting ability was studied depending on the wheel speed, workpiece speed, workpiece material and grain size. The result of grinding force measurement and SEM observations of grooves and grains tips show specially that by increasingthe wheel peripheral speed the cutting ability of the diamond grain expressed in terms of grinding forces, grinding energy and area ratio between the bottom and the sides of the grinding streaks increases and its wear decreases.

Ultra Precision Diamond Cutting of Single Crystalline Silicon

Silicon, a novel and highly useful material, has drawn a lot of attention in different industries recently. Conventionally, a number of material removing processes have been used to produce silicon wafers in semiconductor industry. In order to substitute ultra precision diamond cutting (UPDC) for these conventional processes, continual research has been carried out on the deformation behaviour of single crystalline silicon (100)under ultra precision diamond cutting(UPDC). Machined surfaces were analysed with a scanning electron microscope to observe the surface profile pattern, and also surface roughness was measured by roughness measuring equipment. Finally, with the aim of having the best surface roughness, the optimum cutting conditions have been determined.

A STUDY OF ROUND TIP-SAW TOOTH WEAR RESISTANCE ON THE CUTTING OF THIN-SHEET AUSTENITIC STAINLESS STEEL

In this paper, tool wear resistance in the cutting SUS 304 with several kind of tooth material and shape have been investigated to seek after a suitable cutting tool. A relations between wear states, cutting force, burr on the cut surface and cut layer were also investigated. The main results obtained are as follows: (1) Tool matelrial which had exceedingly high fracture toughness, showed the superior wear resistance and the least burring on the cut surface. (2) After comparing T,B and BC-type shapes, the T-type was the best shape for wear resistance, showing the least burring on the cut surface.(3)Tool wear caused increased cutting force, increased burring height, and a transition of chip shape. (4)Chip shape changed from segmental to continuous chip, and this can be a useful indicator of tool wear in the industrial manufacture.

Judgment on Tool Life of Ball End Mill, Using the Acoustic Emission Signal through Fluid.

This paper will introduce a new sensor coupling device for milling machines and for the machining Center. In industry, there has always been the need for practical application of the sensor coupling device to judge tool-life-related signals from the tool side. A mounting device which enables the sensor to be fixed close to the rotating cutting tool has been developed to meet this need. Thus a more practical method for detecting the tool life of end mill cutting becomes possible. The machining-process-associated signals are high-frequency acoustic emission signals detected through the cutting fluid.

High Precision Cutting of Aluminum Alloy Reinforced by Short Fibers of Alumina. (2nd Report). The Mechanism of Fiber Falling Off at Generation of Finished Surface.

The purpose of this study is to generate higher precision surface of aluminum alloy reinforced by short fibers of alumina experimentally. So, linearly increased depth of cut type cutting is adopted because of being able to vary the cutting force which is concerned with the mechanism of generation of finished surface. As a result, the pore which was caused by fracture and falling-off or falling off thoroughly of fiber was generated in finished surface. As the stress condition around fiber was nearly constant under the same tool geometry, the ratio of depth of pore to the fiber diameter was constant. And, if tool geometry was properly selected with three dimensional cutting, it was feasible to generate the least defect surface.