The vibration caused at the gear mesh is transmitted to the gear box through the shafts and the bearings, and the gear box radiates structure-borne noise. A method of simulation is developed by integrating vibration analysis and acoustic analysis to evaluate the sound power radiated from a gear box, and is applied to a single-stage spur gear system. Vibration transmission on the gear box is analyzed by using the substructure synthesis method. The sound power and the sound intensity, as well as the radiation efficiency, of the gear box are evaluated by the boundary element method. In this evaluation, the velocity distribution on the surface of the gear box, which is obtained by the vibration analysis, is used. The evaluated sound power is compared with the results of sound intensity measurement and they are found to be in good agreement. To reduce the computational effort, a sound power evaluation based on a few conspicuous mean square velocities is presented.

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End milling of a sculptured surface has been attempted by an articulated robot with six degrees of freedom. In this application, the machining error caused by positioning accuracy and rigidity of the robot should be taken into account. In order to minimize the machining error, postprocess error compensation has been realized. Motion of the robot is defined by six joint angles, and it could be controlled if six joint angles are modified according to the machining error. First the mathematical model of the robot was formed, then kinematic equations and differential relationships among them were derived. Joint angles to be modified were calculated using these equations, and motion of the robot was compensated according to the machining error after experimental end milling. The average machining error was reduced from about 100 μm to 40 μm after two error compensation postprocess. This machining accuracy was limited by the repeatability of the robot used in the experiment.

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Copy milling of a sculptured surface has been attempted employing an articulated robot with six degrees of freedom. For this purpose, we developed a sensor feedback teaching system as a previous stage for constructing an off-line teaching system. First, the mathematical model which represents the robot used was established, then kinematic equations and their differential relationships were derived. Joint angles of the robot, which realize adaptive configurations for end milling, were calculated using these equations. In this sensor feedback teaching system, a laser displacement sensor is used to detect the distance between the sensor and the tracing object for copy milling, and joint angles of the robot are determined in order to keep the distance constant. In this way, time series joint angles data are calculated automatically, and the teaching program for the robot is developed. The sensor feedback teaching system was examined by tracing a Mickey Mouse mask. The teaching program developed by this system was executed successfully, and a relief of Mickey Mouse was obtained by experimental copy milling.

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The study deals with the generation of 6-axis-control collision-free polishing command data of an industrial robot with 6 degrees of freedom. Workpieces with, for example, a sheer wall or overhanging curved surface, are difficult to polish using normal rotational tools, since collision between the polishing tool and workpiece cannot be avoided. Thus, an L-type rotational tool consisting of a tool axis and an arm axis was devised, where the angle of the tool axis to the arm axis can be set arbitrarily. In generating the tool path for the L-type rotational tool, the 6-axis collision avoidance concept, consisting of two stages, is newly introduced, based on our own CAD/CAM sysetm. The collision-free polishing path generated is converted into robot control commands for actual polishing work. It is experimentally found that the system is valid for polishing workpieces with complicated shape.

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This paper presents design decision-making methods considering flexibility for a working environment. In order to make a clear evaluation of the changes of the most preferable levels of the product performance and product manufacturing cost due to changes in the working environment (flexibility conditions), three objective design optimization problems are constructed having the three objectives of maximization of the product performance, minimization of the product manufacturing cost and maximization of flexibility for working environment. The Pareto optimum solution set forming a curvature is obtained. Then, a decision-making method for determining the preferable design solution using information from the Pareto optimum solution curvature is presented. Finally, the proposed methods are applied to design examples for demonstrating effectiveness.

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This paper presents methodologies for generating conceptual designs of a structural system, in which structural shapes, inner structural organizations and a functional element are, as much as possible, created without any preconceived information from an element likened to a seed, that is, the initially given detailed information is kept to a minimum. First, a feasible design region initially containing nothing is defined. The entire feasible region which is uniformly filled up with finite elements having extremely low rigidity is here assumed to be a region containing nothing. Then, a seed element grows into an entire structural system in the feasible design region by both creating external shapes and growing inner structures. Next, the design method is advanced so that a functional element of a rotational joint is also simultaneously generated with the structural shapes. Finally, the proposed methods are demonstrated using conceptual designs of industrial robot-like structures having the functions of hanging and transporting an object.

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There is a growing need for top-down design methodology for a discrete event system. In top-down design of the discrete event system, we begin with a high-level model of the system and refine it step-wisely until a sufficiently low-level model is obtained. In the previous researches, most of the proposed refinement technique has been a "transition-based technique", which replaces each transition with subnet. However, in case of assembly Petri net, each place has useful informations for the refinement rather than each transition. This means that a "place-based refinement technique", is needed for assembly Petri net. In this paper, we propose a new place-based refinement techinique of Petri net for automatic assembly procedure. In the proposed method, we assign some attributes to places and set the input-output relationships of transitions which connect the place-attribute combinations. The places can be divided into groups according to their attributes and we should take into account only transitions between these groups. This leads to that we can refine the Petri net easily comparing with the usual transition-based technique.

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Recycling has been recognized as one of the effective solution tools against environmental problems. In this respect, manufacturing systems should take recycling into consideration. We discussed issues contained in recycle-oriented manufacturing systems, and the basic parts flow in the life cycle of the product was clarified by taking account of reuse and reproduction activities for the parts in consideration. An optimization model was constructed in order to maximize the total profit as well as the recycling rate. This problem was analyzed using a goal programming method with multiple objectives. Finally, a numerical example was demonstrated to show the effectiveness of the model proposed.

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The shot velocity in two pneumatic shot-peening machines has been examined by means of experiment and theory. The shot velocity was measured under various operating conditions by a high-speed shutter TV camera. As a result, the shot velocity over the usual range of shot diameter D, shot density p, and air-pressure p was related by the formula, V=K·D^α·ρ^β·(p+p_b)^γ, where P_b is atmospheric pressure. α and β are almost independent of the shot-peening machine, and α ≈ 0.36, β ≈ 0.48, K and γ are dependent on the shot-peening machine. On the other hand, the theoretical consideration based on hydrodynamics tied to the derivation of the formula, V=K·D^-0.44·ρ^-0.44·(p+p_b)^0.43 for the suction type machine, and almost the same formula for the direct-pressure type. The theoretically derived formula coincided well with the experimentally induced formula.

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