In a previously reported analysis of abnormal sounds quantified in terms of acoustic pressure level, there were problems such as insufficient information on high-frequency sounds. In the present study, quality characteristics of in-car devices were considered in a wider sense and a new analysis was performed, in which vibration acceleration of in-car devices was used to evaluate operational functions. In the post-assembly inspection of in-car devices for abnormal sounds, inspectors have been evaluating operational sounds qualitatively by subjective human criteria. As these criteria vary from one inspector to another,in some cases defective products are misjudged as normal and are shipped to customers. In the evaluation of operational functions of in-car devices in this study, operational sounds were replaced with a numerical vibration acceleration value and multivariate continuous data were analyzed by the RT method. By establishing fixed inspection criteria, we are hoping to achieve more accurate product discrimination and to automate the inspection process.
To optimize the selective laser sintering process in a laser metal sintering hybrid milling machine and to shorten development times, the process conditions were evaluated in terms of the power used in subsequent milling of the processed workpiece and studies were performed using parameter design and the Mahalanobis-Taguchi system. When the optimal conditions obtained from these studies were used as in-house standards, several problems emerged, including reproducibility of the gain. These problems were reexamined in several ways, including further experiments, for the purpose of establishing a method of using milling power to evaluate sintering conditions. Specifically, we reexamined the calculation of cut weight, noise factors, measuring methods, and evaluation methods. After the reexamination, another experiment was carried out and the results were studied.
Shaft vibration in jet engines has a direct operational cost and also impairs riding comfort with noise etc., making it a primary factor in lowering the level of customer satisfaction. From a safety standpoint, excessive vibration also accelerates fatigue damage to structures and can lead to serious accidents. Rotors have conventionally been designed so that their critical damage speed stays clear of their operational rotation speed area, leaving a certain margin to allow for the effects of variation. However, if vibration is viewed as energy, shaft vibration can be considered as a phenomenon in which a jet engine system loses energy in the form of vibration and the accompanying sound and heat. Suppressing this energy loss, with consideration given to variation, could be expected to improve total system efficiency. In this study, a shaft vibration design from the new viewpoint of minimizing energy loss was attempted. Using Taguchi methods, a design aiming at a system in which energy loss is minimized in the presence of variation was performed and the result obtained was compared with a design performed from the conventional viewpoint.
Error root mean square is a method in which the general mean and error variance are obtained using the S/N ratio of a nominal-is-best characteristic, and their ratio to the variance of the unit space is used. In the RT method, a distance is obtained using variation and sensitivity, which is a mean effect. This method is conceptually similar to error variance. Liver disease data were used to compare error root mean square with the RT method. As different items of liver disease data uses different units, the data were standardized and the differences between the results of analysis with and without standardization were studied. A strong correlation between the two was found. A normalized scale is presented in which the error variance of the unit space is calibrated to obtain an error root mean square.
In the first stage of the robust design of lens actuators, previous practice has been to evaluate each subsystem independently. For more efficient research, in this study it was decided to evaluate the generic function of the total system. As a system generally involves multiple physical fields, a CAE evaluation of the total system requires coupled simulations. The electromagnetic actuator systems used in lens actuators have a structural field and a magnetic field, requiring a coupling of structural simulation and magnetic simulation. The huge amounts of time taken by such coupled simulations have been a problem. When the generic function of the total system was evaluated in this study, the evaluation model was rationalized and more efficient coupling techniques were devised. As a result, it became possible to optimize the total system, stabilize its function, and improve its quality. The effectiveness of the new techniques was confirmed in a separate application to an SIDM (Smooth Impact Drive Mechanism) actuator, another system having structural and magnetic fields.