As manufacturing activities have been getting globalized and product models have become more and more diversified, animated work instructions for assembly sequence have been increasingly employed to assure product quality. However, assembly sequence planning and subsequent animation editing time drastically increases and becomes unacceptably time consuming in the order of factorial as the number of assembly parts grows. To address this problem, a fast assembly sequence and assembly motion generation method has been developed based on assembly parts constraints and parts layout in CAD assmbly models. Generated assembly sequences have then been automatically translated into animation scripts and eventually been employed as animated work instructions in actual manufacturing sites.

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[in Japanese]

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In this research, a four-dimensional mesh model has been proposed for construction of a cyber field which manages dynamic states of object models. The four-dimensional mesh model is generated by 4D-Marching Cubes algorithm and contains a great number of vertices and tetrahedrons; therefore the four-dimensional mesh model requires massive amounts of system memories. In this report, for reducing computational resources, the method for conversion of the four-dimensional mesh to a streaming mesh format is proposed. The streaming mesh format allows sequentially constructing a large model. In addition, the four-dimensional mesh simplification algorithm based on QEM is proposed. These methods are implemented and the efficiency of these methods is demonstrated from the results.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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The paper deals with a CAM kernel independent of platforms. In the recent years, CAD modeler have become popular. However the products using domestic kernel have been decreased. Moreover, efficiency of development of a software is made lower by dependency on a platform. We are aiming to develop open CAM kernel independent from platforms. IGES a general-purpose intermediate format of three-dimensional CAD data is used in the system as a native format. In this paper, we report outline of the system and a sample CAM system based on the system.

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Given a 3D surface mesh M and its corresponding tetrahedral mesh (tet-mesh) T, a novel approach based on graph cut is developed to compute the segmentation of the model T into non-overlapping and compact components with perceptual meaningfulness. The algorithm is simple to implement and completely automatic,and generates a binary tree of components in which the root is the whole 3D tet-mesh T and the leaves are all meaningful sub-tet-meshes. The approach is implemented top-down by partitioning a component into two parts each time until each part is a perceptually meaningful component.

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[in Japanese]

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Bilateral image filter has recently become very popular because of its simplicity and feature-preserving ability. We introduce a novel approach to fast bilateral filtering, in which includes linear computational complexity and user-specified precision. The approach is based on combining a dimension elevation trick with a Fast Gauss Transform. We also demonstrate the results of denoising and HDR tone mapping applications.

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[in Japanese]

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We propose a segmentation method for X-ray CT images of skeletons. Our idea is the use of functional images, or results of physical simulations for CT images. In our study, we apply voxel based physical simulation to the CT images taking into account Young′s module computed from CT values and remove voxels with the highest strain on surface. We iterate this procedure to decompose a set of skeletons. This approach is efficient for segmentation of noisy biological X ray CT image(s) which are usually low resolution and strongly blurred. Indeed, this paper demonstrates several examples can be decomposed correctly, whereas they are failed with conventional methods.

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The performance of the three-dimensional non-contact measuring devises (3D laser or industrial X-rays CT scanning devices) have been rapidly developed, and it increases the importance of reverse engineering(RE) where 3D CAD model is reconstructed from scanned mesh model measured from real objects. However, existing reverse engineering methods cannot recover the feature-based model representations that might be defined in CAD systems, therefore the reconstructed CAD models cannot be easily faired and modified for the effective use in downstream applications. The purpose of the research is to propose a new algorithm that robustly detects the defining parameters of revolved features from the scanned meshes including scanning error and noise. Revolved feature is one of the popular CAD modeling commands and is widely used for designing engineering objects. We also developed the system that can import a set of geometric parameters into CAD systems and automatically creates 3D CAD models.

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Since the decisions in the early design stage make large impact on all life cycle of product, iterative design refinement and simulation-based verification in the early stage are important for efficient product development. A number of analysis methods have been proposed as analysis tools for the early stage. However, since most of them are based on analysis methods for a continuous object, it is not easy to apply them to the analysis of the object composed of continuous and discontinuous elements. In this report, in order to enable simultaneous operation of shape modeling and deformation behavior analysis in the early design stage, a method for simulation-based design support using distinct element method (DEM) which is suitable for the analysis of the deformation behavior from the continuous object to discontinuous object is proposed.

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[in Japanese]

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[in Japanese]

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Die designers need to fill the holes in the product surface data in order to create the corresponding stamping die data. Conventional methods for hole-filling calculated the filling surface mathematically from the continuity conditions along the hole boundary curves, but often the result surface was not adequate for the stamping process. Based on the idea that the shape of the plane panel when pressed towards the product surface near the hole would be appropriate for the stamping process, the authors developed a new method in which the panel deformation is computed using a CAE simulation and the hole-filling surface is created from its result.

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Recently, large and complex geometric models can be easily created and acquired by the spread of 3D CAD systems and the progress of 3D scanning technologies. However, it is more difficult for users to recognize these models which have complex internal structures or consist of many parts. We proposed a cutaway model representation system using a three dimensional user interface for an easier recognition of the complex models. In this report, we introduce a method for efficient cutaway model generation using model simplification and temporal coherence. In this method, model simplification is used to reduce the number of triangles to generate and represent cutaway model, and temporal coherence can efficiently update the inside-outside information of the triangles.

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[in Japanese]

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The purpose of this study is to propose the internal magnetic polishing method of grooves of magnetic materials, and to examine the polishing characteristics. Most of dies as workpieces are made of magnetic materials. When such dies are finished by the magnetic polishing, some problems are liable to occur; for example, ferromagnetic particle remains on the surface of workpieces by the magnetic attraction force. In addition, in the groove polishing of magnetic materials, the ferromagnetic particle is concentrated to the groove edge, and there is a problem that the polishing becomes insufficient at the inner surface. In this paper, by clarifying of the internal magnetic polishing characteristics in groove, polishing mechanism in various grooves was examined.

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[in Japanese]

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The purpose of this study is to find out an effective method to elevate the surface precision and homogeneity by improving the polishing trajectory of magnetic brush. Plane magnetic abrasive finishing is a kind of precise polishing method which uses the magnetic abrasive particles as the cutting tool. The moment of magnetic brush is a key factor affecting on finishing results, while movement is relatively simple in conventional process. In this paper complex polishing trajectory of magnetic brush has been modified and studied by use of newly designed experiment device. The linear movement of workpiece, the rotation and revolution or movement in XY coordinate plane of magnetic brush can be realized by this device. In comparison with conventional method, variation regularity about surface roughness and the material removal are been studied. According to experimental results for polishing trajectory of magnetic brush, a lot of characteristics have been summarized. The results show that studies on polishing trajectory of magnetic brush are more valuable and the experimental researches are consistent with theoretical analysis. In addition, the accuracy of plane magnetic abrasive finishing can be elevated in terms of the reasonable planning for polishing trajectory of magnetic brush.

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As information equipments such as laptop computers and cell phones are recently becoming thinner and smaller, the high-frequency quartz devices installed in these equipments are also needed to be extremely thin. Therefore, the efficient thinning process of the quarts wafers is strongly being required. This paper aims at the development of a novel polishing technique suiting for the thinning process of quartz wafers not only with high surface quality but also with processing efficiency compared with the conventional method. For this purpose, a semi-bonded abrasive tool produced by putting a Magnetic compound fluid (MCF) onto the circumference surface of a ring-shaped permanent magnet has been proposed. In this report, the fundamental polishing characteristic are experimentally investigated in the polishing of quartz wafers. The results show that the material removal rate reached 0.3 μm/min without any surface damages such as cracks and pits.

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[in Japanese]

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We continue to develop the Reverse engineering software MOSAIC. The characteristic functions of MOSAIC generate NURBS surface quickly without interactive operation, and output suitable CAD like modeling results. Our method is based on a segmentation method with region growing using plane proxies. We propose new segmentation using curve proxies.

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Recently, 3D CAD models have been widely used in product developments. And large scale assembly models need considerable time, when being read, rendered and browsed in 3D CAD system. But for browsing, only visible parts and form features in the model are needed. Therefore, we propose a technique to simplify large scale assembly models of 3D CAD by eliminating their invisible parts and form features, while keeping constraint conditions among parts to saving the assembly structure. In this report, we propose a method which guarantees the appearance of the model even under the positional and orientational change in moving parts.

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3D CAD systems are widespread even at the upper stages of product design. Although most 3D CAD models are designed and stored for use in product design, few studies have reported shape retrieval for use in assembly models. In this study, we propose a new 3D shape retrieval method of assembly structure. The features of the component shapes and the assembly structures are extracted from 3D CAD models. A similarity between the two assembly models was found by comparing both the geometric feature of every component and by comparing the contact states, interferences and constraint conditions between the components. In this report, we improved the retrieval ability by introducing the stretch-based mesh quality improvement and uniform point sampling when calculating the component shape feature, and compared the retrieval results of previous method with the ones of the improved one.

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[in Japanese]

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Recently, 3D CAD software has become more comprehensive and has been added many functions. Because of it, the number of commands becomes enormous, therefore, it becomes harder for CAD users to find the command they want to choose. In this study, we a developed Predictive Command Tool for 3D modeling which suggests frequently performed commands for each modeling context. Most probable choices of command are selected based on a user′s operation history and context-based inference. The software shows these most probable commands nearby the mouse pointer, so that a user doesn′t have to move mouse so much. The author′s previous study indicates that the proposed tool reduces mouse movement by 30%.

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The surfaces of automobile interior parts have geometrically microfabricated, which are called grain. The purpose of our research is to mill dies with grain by use of their digital data. We generate microfabricated geometry data from a CAD model of a die with a image quilting method extended into 3D and displacement mapping. With these geometry data, the die with grain is manufactured by milling.

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[in Japanese]

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In this paper, a novel approach for designing grain patterns based on digital technology is proposed. In previous paper, the growth model of trees was made by investigating the feature of growth of trees and the response to the environment of trees. And a method of generating digital trees by using electric charge was proposed. In this paper, in order to generate more natural woodgrain patterns which can be used for industry, the method of more precise digital trees construction is proposed. And a design system is developed towards utilization. The digital woodgrain patterns acquired from the system are evaluated.

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[in Japanese]

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[in Japanese]

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Since human hands play an important role in grasping and manipulating the product, the digital hand model which can reproduce the structure and the motion of the human hand is very useful for virtual ergonomic assessment of the product. In this paper, we present the new method to construct the bone link structure and skin deformation algorithm of the digital hand based on the bone and skin surface model extracted from the MRI. The constructed digital hand can reproduce the finger motion and skin surface shape. Moreover, we estimate the more accurate contact areas of the human hand with the real product using the digital hand and the product model.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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In the manufacture of industrial products, utilization of reusable parts recovered from used products makes the environmental impact of manufacturing be reduced compared to utilization of brand new parts. It is important that the eco-efficiency incorporating the concept of efficiency should be enhanced rather than the absolute reduction of environmental impact for sustainable growth. In this study, industrial products consisting of reusable and brand new parts are assumed to be in the open-loop and closed-loop circulation system. Effect of physical life distribution of reusable parts on the eco-efficiency is investigated with the consideration of cost constraints and the optimal distribution maximizing the eco-efficiency is studied.

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This is a report of research conducted on a consumer's disassembly in a product life cycle.And, it is summarized about design for Easy disassembly of environment-friendly home electrical appliances and telecommunications products.

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Natural fiber is paid attention as an environmentally superior material. It is known that a bamboo has higher growth speed. Therefore, we proposed a sustainable manufacturing system using bamboo. An extraction method of bamboo fibers end-milled from bamboo using a machining center with in-situ measurement is proposed in the previous report. As a result, it was shown that bamboo fibers with high precision shape could be acquired efficiently. In the present report, fabrication of binder-free composite was performed using the bamboo fibers by hot press forming method.

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In this paper, small-sized ultrasonic impact machining device without using loose grain has been developed, aiming at the reduction of the cost, miniaturization and the simplification of the device, and investigation of the machining possibilities of this method. In this study, experiments of machining glass work pieces were carried out. In the experiments, a diamond tool vibrated with high frequency was pressed directly on the glass workpieces during a machining process. As a result of this study, effects of the machining conditions such as static load and amplitude of tool, feed rate on the machining characteristics were clarified.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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In external turning of carbon steel with ultrasonic vibration (USV) it is clarified that compressive stress remains on the machined surface. The factors which may influence the generation mechanism of residual stress, e. g. , surface temperature, strain rate and vibration mode are investigated in detail. The results obtained are as follows. The temperature rise in turning without USV, which is higher than with USV, causes higher tensile residual stress on the machined surface. On the other hand, a workpiece is always machined at several times higher strain rate in turning with USV than without USV. As a result, an increase in strain rate raises the yield stress and, in turn, results in an increase in compressive residual stress. USV cutting apparatus used in turning generates not only a major vibration in the primary cutting direction but also a minor vibration in the direction perpendicular to the machined surface. The latter vibration beats the machined surface, which results in the enhancement of compressive residual stress. Thus, this compressive residual stress prevents the occurrence of crack on the machined surface, which also leads to an increase in corrosion resistance.

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