[in Japanese]

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“Virtual Manufacturing” is one of the most effective techniques to make a model of manufacturing systems and simulate manufacturing processes. In this paper, Virtual Shop Floor (VSF) is investigated as a first step to make Virtual Manufacturing Systems. VSF is a computer system which supports designing and operating desirable shop floors in various manufacturing environments. A new concept of Open System Architecture for Virtual Shop Floor (OSAViS) is proposed, in order to make VSF fast enough, so as to be able to follow the changes of a manufacturing environment. OSAViS is an architecture for making a modularized and distributed VSF. The modularization of the system enables us to build the various shop floor models with the combination of various modules. The distributed simulation can be performed fast, because it executes simulations of the shop floor in parallel. In this paper, a basic concept of OSAViS is explained. A model of a shop floor, a way of making each module (named VSF Module), and a framework of a distributed parallel simulation system are investigated.

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A method for reconstructing surface meshes from measured data points is proposed. The points are obtained by laser scanning 3D shape measurement equipment. The method is based on “Implicit Function Reconstruction” method, in which the mesh is generated by iso-surfacing a potential field in 3D voxel space. A new approach for defining the potential field from the measured data points is described. As the principle of this approach, “space curving” method is used for classifying voxels and calculating potential values. Using this method and approach, a prototype system is developed for reconstructing meshes for complex objects. Some examples demonstrated the performance of the system.

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Loading behaviour of the grinding wheel is investigated based on working surface topography. For on-machine measurement of working surface profile, the laser micrometer is directly fitted on the wheel head of CNC surface grinder. Mild steel (S 15 C) easy to load is ground with an aluminum oxide grinding wheel (WA 60 J 7 V). From the comparison of profile and micro-observation of working surface, the following results are obtained : There are two types of loading ; deposition type loading is caused by the chip deposited in the chip pocket and welding type loading is caused by the chip welded on the cutting edge. With the progress of loading, the relative frequency distribution of working surface profile which we newly proposed shows changes in its pattern; firstly whole of the distribution shifts to the plus direction of the amplitude, and secondly the relative frequency of the higher region of the amplitude increases. The shift of the distribution corresponds to the progression of deposition type loading and the profile change of the distribution corresponds to the progression of welding type loading. These changes are distinctive, then qualitative evaluation of the loading is possible.

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Stainless steel pipe with fine hole and long size has recently been needed for the flow line of pure gas and liquid, which is used in the field of precision machinery. Inner wall polishing of the capillary is very difficult by ordinary finishing methods. High speed slurry flow finishing method developed by authors has been proved to have excellent polishing performance, but it has been needed a long time to obtain an acceptable level of surface roughness decrease. In the present study, effect of an annex of the glass beads into the slurry on the efficiency of finishing has been investigated. Experiments show that the medium of the glass beads annexed into the slurry has fine finishing characteristics rather than slurry medium. Surface roughness decreases with slurry flow pass number and its decreasing modes vary due to the property of medium. Optical micrographs of the medium indicate that the glass bead does not crush and not slenderize during finishing processes.

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The present contribution is an attempt of the optimal machine tool control in turning to follow a desired tool position with better surface finish characteristics. In order to evaluate surface finishes during machining, a new simple measuring system has been proposed which uses an optical parallel substrate based on a light reflection technique. A tool position control by the LQI control is designed to reduce the tracking error between the tool and the workpiece surface. For this aim, a compensatory flat tool attached to the specially designed tool servo system is compensated for so that the tracking errors in following a desired tool position are removed. The improvements in surface finish are clarified by the roughness measurement with a stylus instrument.

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A new experimental method of in-process dressing has been conducted by means of water-jet, as well its application investigated in the present study. While the workpiece is difficult to be ground by the surface grinding machine, the high pressure waterjet is supplied to the grinding wheel as a supplementary method. The principle of this method can be simply described as that the waterjet is a kind of processing technique, which is able to strip the chips on the surface of the grinding wheel without damaging it by adjusting the injection pressure and stand-off distance. The dressing effects are examined according to the surface conditions of the grinding wheel and ground workpiece by a surface roughness and profile measuring device and a microscope. Because of the complexity of the interaction influences between the jet pump pressure and the stand-off distance on the dressing results, in this report at fixed stand-off distance condition the effects of the jet pressure on the grinding wheel of CBN #325 and finished surface of Ti6A14V materials have been clarified. From the results of the experiments, it was found that the dressing life time of the grinding wheel and the roughness of the ground material finished surface have been improved distinctly when the injection pressure is 107.1MPa at stand-off distance 20mm. On the other hand much lower pressure will have no influence on dressing results, and much higher one will damage the CBN wheel.

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The present paper proposes a new type of layer manufacturing of micro structural/functional parts using laser sintering. Technical innovation lies in the use of green tape made of micro powder, organic binder and solvents in a process based on conventional selective laser sintering. First, the process architecture is explained to differentiate the proposed method from others, then a feasibility investigation is discussed. Some metal powders, including copper, nickel and steel, have been sintered under various process parameters such as laser beam power, scan speed and scan spacing. Carefully controlling the parameters as well as the repeating deposition and pattern creation produces three-dimensional metal parts on a stainless steel substrate. Strength, density and microstructures are also examined to characterize the sintered parts. The copper object as sintered has a density of 4.5 g/cm³ and a maximum tensile strength of 40 MPa. A hybrid structure of steel and nickel can be fabricated through layering both powder tapes by turns.

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Single crystal silicon is machined with a straight-nosed diamond tool and the fundamental machining characteristics are investigated. By obtaining the critical depth of cut based on a simple geometrical model, the effect of crystalline anisotropy on brittle-ductile transition is studied. A homogeneous smooth surface is obtained by controlling the undeformed chip thickness below the minimum critical depth of cut. The cutting chip morphology and machined surface texture with the variation of undeformed chip thickness are observed. An intermediate cutting mode is found to exist between the ductile mode and the brittle mode. Ductile regime turning with generating continuous ribbon chips is realized at a large tool feed rate. By adopting a diamond tool with chamfered rake face, the machined surface roughness is improved.

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In this study, a new grinding method and a grinding system with the inclined rotational axis of micro grinding wheel were developed. In the previous report, the wheel was formed to a precise columnar shape of 0.8 mm in the diameter by a single crystal diamond truer on the machine. By the developed system, in grinding test of the workpiece of about 0.7 mm radius curvature, the form accuracy of about 0.1 μm P-V and surface roughness of less than 0.03 μ m Ry were obtained. Recent trend is the further micronization of aspherical optical components. Therefore in this report micronizing of aspherical surface was examined by the ultra-high speed grinding spindle of 15 × 10⁴ rpm at the maximum rotational rate and micro wheel of about 0.3 mm in radius curvature. In the grinding test, WC (tungsten carbide) molding die of less than 0.3 mm radius curvature was tested and the form accuracy of about 0.1 μ m P-V was obtained.

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This paper deals with an improvement of the telemetering system for practical use. Large capacity rechargeable battery and power supply regulator are adopted and 22.5 hours continuous measurement is confirmed. Output of the telemetering system with thermocouple hot junction short-circuited to the spindle is fluctuated accompanied by spindle rotation. For this fluctuation the following three procedures are applied and the measurement accuracy of the telemetering system with error less than 0.1°C is confirmed : low-pass filtering, using averaged data of temperature and shortening the length between two contact points of thermocouple hot-junction contacting with the spindle. Also the inner-surface temperature of inner-race of rolling bearing is measured.

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Honing is an abrasive machining process that rounds, smoothes and enlarges bores in end products. It needs, however, a uni-purpose machine tool. Then a honing unit, which can be used on a machining center, has been developed to cut new investment in plants and to automate a honing process. This unit is light and compact, so that it can be inserted in the tool magazine of a machining center. From the experiments on its performance, it is made clear that this unit can produce good degrees of roundness, roughness and cylindricity. A soluble type of coolant can be used in the honing of cast iron. The lead time can be fairly reduced, because a workpiece has not to be unloaded when this apparatus is used. The developed honing unit brings many advantages over the conventional method especially in the case of job shop type of production. The possibility of realizing automation, saving cost and time, is much increased.

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This paper presents a method of machine instruction code generation for multi-axis machine tool instead of the conventional manner. In the present method, each working part of multi-axis machine tool, cutting tool, and fixture are modeled as autonomous components and a mechanical simulation system is constructed by these autonomous components to simulate machining operation for multi-axis machine tool. NC instruction codes are generated by extracting motion of working parts made by performing mechanical simulation system model as the operative closure system served by mutual feedback among autonomous components under the constraints that are relation among working parts, cutting condition between cutting tool and workpiece, and interference with motion of cutting tool. This paper describes the concept of NC instruction code generation by performing mechanical simulation system as the operative closure system proposed in this study and details of evaluators and operators coded into the autonomous component for constructing such mechanical simulation system. Then effectiveness and feasibility of the proposed method has been estimated by performing the simulation and actual machining.

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The paper deals with machinability of boron nitride (BN) added steels. BN has hexagonal system, and the nature is similar to graphite so that it is used for solid lubricant in general. In this study, plain carbon steel S45C and BN added steels, which has also 0.45% carbon content, were machined by P grade and K grade carbide tools and an alumina ceramic tool. In turning the BN added steels, P grade tool had fairly smaller flank wear than that in turning 545C at the cutting speed of over 200 m/min and the effects of the good machinability kept even at the cutting speed of 500 m/min. At the lower cutting speed, however, the wears in turning the BN steel and 545C were almost the same. Furthermore, in the case of K grade carbide tool, the wear in turning the BN steel is almost the same as that in turning the S45C even at higher cutting speed, and the ceramic tool showed the same results as K grade tool.

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The piezo element as a representative displacement type actuator elicits a high-speed response. Recently, there has been much research carried out using this feature. In order to progress the control performance, we previously proposed the motional-mode-based decoupling control scheme for a three-degrees-of-freedom fine-motion stage with piezo elements. In the meantime, we proposed the collocation compensation method to realize the desirable positioning. As is well known, the controlled object on the condition that the actuators and sensors are collocated shows good control performance. Then, it is expected that the motional-mode-based decoupling control together with collocation compensation can realize the good performance all the more. However, this paper shows that the collocation compensation for the above control scheme has an effect on the only difference of the loop-gain for each motional mode. This result is useful for the mechanical design.

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An Abramson interferometer has been known as one type of oblique incidence interferometers. It can record an interferogram for rough or uneven nonoptical surfaces. However for a fringe analysis, a conventional multi-step phase shifting method has difficulties in applying to this interferometer because of quasi-common path arrangement in optics. For the solution of this problem, the Abramson interferometry using a one-step phase shifting method is proposed. For practical applications, two problems are overcome in this interferometer, elimination of the influence of multi-reflection and decreasing of error due to deviation from the reference carrier frequency are proposed in this one-step phase shifting method. A spatial filter is set up in optics and a revised algorithm in one-step phase shifting method is proposed. An experiment is made for demonstrating availability of this method using a Si wafer.

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Positioning control with a resolution of nm order is performed using high-power electrostatic linear drive. The authors have developed high-power electrostatic drive called DEMED (Dual Excitation Multiphase Electrostatic Drive). DEMED, espe- cially its linear type, has performed superior dynamic performaces such as a power per weight ratio of 230W/kg and a maximum acceleration of over 100G. In this paper, the first trial of servo control of linear-type DEMED is described. Firstly, the thrust force of DEMED is simply modelled for designing controller and one method of feedback control for single frequency driving method is proposed. Secondly, an electrode position sensor, which is necessary for feedback control, is proposed and fabricated. Finally, high precision positioning control is performed. For the experiments, a linear table which equips an optical linear encoder with a resolu-tion of 6.25nm is fabricated. A linear and stacked type of DEMED is mounted on the linear table. By feeding two different feedback gains depending on the positioning error, positioning control within ±1 pulse (=6.25nm) is achieved.

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A novel method called PDSV, realizing 3-D measurement over a wide range than the original DSV is proposed. The method includes estimation of inclination at the measured point, that of the shape deformation of corresponding region in stereo images and that of variance of error for each variable (intensity change, depth and inclination). As the result of shape reconstruction by using self-estimators, more reliable data can be obtained.

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For the progress of micromachine technology and microfabrication technology, it is necessary to devise a technique to measure both profile and dimension of microparts. Although some researches on measuring methods of a small hole are reported, measuring methods for the profile and dimension of microparts including geometrical deviations such as straightness, circularity and perpendicularity has not been reported yet. It is thought that a small three dimensional profile measuring apparatus with microprobe can be utilized as the measuring method for this purpose. In this paper a new three dimensional profile measuring apparatus which has non-contact probe detecting proximity to measuring object through tunneling effect is described in detail. Then the validity of the measuring apparatus is shown by several experimental results.

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