Model tests of two-dimensional grinding are carried out where the work is made of clay, Plasticine and the mode of grid line deformation of work is observed. The symbols are written on the work surface before cutting in order to investigate the state of the outer and inner chip surface. These experiments give some results as follows: (1) The chip formation in grinding is discontinuous and occurred by shearing deformation that includes large slip. As the rake angle is reduced, the deformation contains squeezing under the cutting edge. (2) When the rake angle is very small, the work surface before cutting remains on that after cutting. The part of the former work surface is sucked into the work on the chip-tool interface. (3) As the rake angle increases or the cutting speed decreases, the mechanism of the work deformation comes to the formation of a continuous chip, the velocity of the chip formation drops down and the transforming area in the cutting direction is expanding.

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The fatigue lives of thin bearing steel plate samples taken in three different directions to the rolling direction were compared by a new-developed bending fatigue testing machine. Observations utilizing SEM-EPMA revealed that fatigue cracks were initiated at the nonmetallic inclusions of the bearing steel. The results obtained are summarized as follows: (1) The inclusions in the vicinity of the surface acted as an initiating point of fatigue fracture in each sample judging from the observation of the directionality of equiaxed dimples. (2) The inclusions giving rise to fatigue fracture were identified for each direction. Namely, fatigue cracks in longitudinal specimens developed at square-shaped Al₂O₃-CaO or TiN inclusions, those in transverse specimens at linear MnS inclusions, and those in oblique specimens at complex TiNMnS, Al₂O₃-TiN or MnS inclusions. (3) Oxide inclusions about 5 μm in length can be the initiating point of fatigue fracture depending upon loading directions.

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The new technique to verify the minimum zone roundness was proposed by improving Nelder-Mead simplex method in consideration of the specific characteristics of cross section contour in cylinder. And the authors investigated the optimum dimension of simplex at the initial stage and reasonable convergence limit in iterative process. Furthermore the minimum zone roundness was compared with the least square roundness which has been widely applied.

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Cylindrical plunge grinding processes of titanium alloy and nickel-base superalloys with various kinds of conventional grinding wheels, which are known as difficult to grind materials, are experimentally investigated, analyzing size generation process, grinding force, surface roughness, wheel wear, grinding ratio and so on. For grinding titanium alloy Ti-6Al-4V, GC grinding wheel yields most superior grinding results which leads to lower grinding force, smaller residual stock, less wh eel wear and higher grinding ratio up to about 3 with GC 80 L 9 V wheel. Then, for grinding nickelbase superalloys Waspaloy and Rene 41, WA 150 L 9 V wheel yields better grinding results in surface roughness, wheel wear, grinding ratio without chatter vibration though grinding force is higher, and the grinding ratio about 3 is obtained. Furthermore, higher plunge speed and speed ratio result in higher grinding efficiency though grinding force, surface roughness, wheel wear increase for grinding titanium alloy and nickel-base superalloys.

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This paper deals with a newly developed Numerically Controlled Contouring Electric Discharge Machining (NC-CEDM) system. The proposed NCCEDM is based on the shape standardization of the tool electrodes, and on the contouring control of the standard tool electrode by an automatic programming system, APSET 2, which posesses a function of multi axis numerical control. The features of this machining system are (1) reducing time to machine the tool electrode, (2) increasing the accuracy and productivity of the tool by standardization, and (3) increasing the flexibility of the shape to be removed by the newly developed contouring control programming system. In this paper, the cross sectional profile of the tool electrodes are standardized to n (1≤n≤6) polygon, the corner of which has roundness. APSET 2 has the capability of controlling the tool position and attitude (rotation on the X-Y plane) along the contour. Experimentation with standard electrodes, APSET 2, and a fouraxis (X, Y, Z, U)-controlling NC electric discharge machine have demonstrated the realization of NCCEDM.

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An accurate positioning XY stage has been constructed to help assure submicron pattern generation in electron beam microfabrication. The stage is guided along journal-type hydrostatic bearings, and driven by hydraulic cylinders along X and Y axes. Characteristics of the stage mechanism and servo system are reported on in this paper. Sufficient straightness for electron beam microfabrication is realized. Vertical displacement is 0.9 μm for 80 mm × 80 mm stage travel, and yaw is 4 μrad for 140 mm along the X and Y axes. Automatic regulation of feedback gain allows stable positioning with high accuracy, and servo stiffness prevents interaction between the X and Y axes. Due to these functions, a positioning accuracy of ±0.1 μm for 2 mm and 0.5 μm travel is attained. High speed positioning is also possible due to the high responsibility of the electro-hydraulic servo and miniaturization of the stage mechanism. Positioning time is 0.1 s for 2 mm and 0. 56 s for 20 mm travel.

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The deep-hole axis deviates from the setting axis in drilling operations, and this dominant problem occurs frequently. In the present paper, the influence of pilot bush, bar support and tool holder (or spindle) on the hole deviation is investigated and the mechanism of the formation of that deviation is analysed theoretically and verified experimentally. It is made clear that the machined hole tends to deviate towards the direction of the inclination of tool head in tool rotating system. It s also obsery ed that if the pilot bush or bar support (e. g. oil seal in BTA tool) deviates from the setting axis, the bar bends, makes the tool inclined, and as a result, the machined hole runs out from the setting line. If the process goes on, the rate of deviation becomes larger. On the contrary, in workpiece rotating system, the inclination of tool head usually doesn't keep any constant direction on the co-ordinates fixed to the workpiece. So it will move nearly through the setting axis even if there is any misalignment. Therefore the magnitude of hole-deviation is smaller than that in tool rotating system.

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Improved materials for the hob and the advanced coating technique have created a need for testing the dynamic characteristics of dividing error between the worktable and the hob in order to attain both the high-rate and high-accuracy gear cutting. One of the authors has already developed a new apparatus for measuring the dynamic dividing error between the hob and the worktable. Using this apparatus, the dynamic dividing error was measured and recorded not only during the idle running but also during machining. In this report, seven items of testing method for the static and the dynamic torsional rigidity of the rotational transmission mechanism in a hobbing machine, which strongly affects the accuracy of the generated gear, is newly proposed by including the aforementioned method of measuring the dynamic dividing error. The seven items of testing method is carried out on a middle size precision gear hobbing machine which is one of a specific type widely employed in gear production shops. As the result, it was proved that both the high-rate and highaccuracy gear cutting condition applicable on the tested hobbing machine could be identified. The proposed testing method would also be effective for the manufacturers who use many gear hobbing machines, to examine and maintain the generating accuracy of their production equipments. The seven items of testing method proposed would be effectively applied not only to the middle size but also to the small size and the large size gear hobbing machines.

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The aim of this study is to decide the ideal infeed curve in plunge grinding. In the first report, the size generation process was analyzed quantitatively. In the second report, the effect of in-feed conditions on surface roughness was discussed. Therefore, in this report, taking note of variation process of wheel surface, one of the standards of in-feed conditions is made clear from the viewpoint of wheel wear and surface roughness. Then, the shape accuracy is analyzed theoretically, based on the mathematical model of the plunge grinding which was constructed in the first report. Next, the analyzing model of the work hardened layer, which is one of the most important evaluation functions of quality, is constructed. Finally from these results, evaluation functions of grinding are adapted, that is, total grinding time, size accuracy, shape accuracy, wheel wear, surface roughness and work hardened layer, and then the ideal in-feed curve which fulfills the requirements of high accuracy, efficiency and quality is decided.

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This paper describes the optimum YAG laser welding conditions applied to the manufacturing of a workless on magnet print wire matrix head. The relation between the YAG laser welding conditions and metal structures is clarified. Furthermore, the effects of laser power, amount of defocus and heat treatment temperature are examined in relation to mechanical welding strength. The resulting optimum welding conditions are summarized as follows: laser power is 2.5-5 J, heat treatment temperature is 150-200°C, and the amount of defocus is ±1mm. With these conditions, a welding strength of over 100 N is obtained. The printing head weight is reduced to about 40 g and life is increased to over 10₇ printing times. This means that the weight is one-fifth and the life is twice that of previously reported printing heads.

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In this paper, the sliding behavior and damping characteristic of turning tools are investigated experimentally. The relations among the sliding behavior during loading and unloading process, damping characteristic and the fixing conditionsof turning tools are clarified. Vibrating energy consumption by relative sliding between tool shank and tool rest is an essential cause of damping capability of turning tools. The complex damping capability of turning tools can be put in order by a newly-defined “energy consumption coefficient”.

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Since diamond dressing is basically a fracture process of the composite wheel material, the characteristics of this material itself and the dressing force may well have some vital influences on the dressing result. An investigation has been carried out to study the effects of dressing conditions and grinding wheel's inherent properties such as grade, on the generating mechanism of cutting edges. Size distributions for dressing particles were obtained and SEM observations of the dressed surfaces were made for C to P-grade wheels. The main results obtained are summarized as follows: (1) Small particles of the order of the dressing depth accounts for a considerable percentage, in number, of dressing particles which increases with a harder wheel and with finer dressing conditions. (2) The number of diamond's passages which a grain suffers before falling off increases with a harder wheel and with finer dressing conditions, and consequently this results in an increase in area of flat plateaux on abrasive grains. (3) The number of micro-cracks on dressed surfaces of abrasive grains increases with a harder wheel and with rougher dressing conditions.

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In this paper, a simple detecting method of irregularity of wheel grade in dressing is discussed. The results obtained are as follows: (1) By using the processing circuit which is consist of a diode and filter circuit, it is possible to detect the irregularity of wheel grade from the acceleration output on a dresser. (2) The smaller irregularity of wheel grade is, the more direct current the processed output becomes and the larger irregularity is, the more alternating current it becomes. (3) The amplitude of the processed output is dependent upon the degree of irregularity of wheel grade and becomes large in accordance with the increase of it. (4) Using this equipment, the irregularity of wheel grade can be detected easily on a grinding machine during dressing operation.

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In grinding process, the rotation of a grinding wheel has significant effects on the flow of air and/or grinding fluid around the wheel and workpiece. The permeability of a grinding wheel which corresponds to the grain size plays the main role in the flow through a porous media. The thermal behaviour around the workpiece surface is closely related to the flow pattern around it, and they influences the thermal deformation of a workpiece which is concerned with the machining accuracy of grinding. In addition, to design a rational grindng fluid application system, it is necessary to clarify the thermal behaviour and flow pattern around it. Here experiments were carried out in a dry surface grinding process to measure the distributions of the wall pressure and of the local heat transfer at the workpiece surface. Using the flow visualization by the fluid film and surface tuft methods, the air flow pattern around it was also observed. From the experimental results, it is clear that the grain size of a grinding wheel has a remarkable influence on the thermal behaviour and flow pattern. The air blowing out from the grinding wheel which is caused by the centrifugal force may be considered to act as an impinging jet to a workpiece surface.

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The purpose of this paper is to develop an automatic measuring system based on the optical Fourier transform which can be applied to the inprocess measurement of the characteristics of grinding wheel surface. The power spectrum pattern of grinding wheel surface which is observed by the optical method has some informations with respect to the characteristics of grinding wheel surface, i. e., the width of grain wear flats, the area of worn grains and the number of worn grains. In this paper, the power spectrum pattern measuring device which can estimate quantitatively and directly the characteristics of grinding wheel surface during grinding operation is introduced. And the in-process measuring system is proposed, which consists of a microcomputer, pitch control device, digital memory, rotary encoder, optical device and laser source etc. By developing the in-process power spectrum measuring system as mentioned above, the life time of grinding wheel can be determined in real time from the average width of grain wear flats and the state of grinding operation can be estimated from the distribution maps of worn grains around the grinding wheel surface printed by a teletype.

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The tool life caused by brittle failure in interrupted cutting is analyzed by the application of the fracture mechanics theory. Fatigue crack propagation characteristics which are required in the analysis are determined for cemented carbide P 20 using the single notched beam specimen in threepoint bend test. Fractographic examinations suggest that the mechanism of brittle failure in interrupted cutting is substantially similar to that in fatigue crack propagation process. The linear relationship on logarithmic scales is obtained between the rate of the fatigue crack propagation and the stress intensity factor range. The analytical results show that the tool life increases with the increase in the ratio of vertical component to horizontal component in cutting force, and also increase in the wedge angle and the rake angle of the cutting tool.

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