品質工学 Vol. 24(2016) No. 3

A study was made of the usefulness of introducing virtual parameter design into the technology design process, at the stage following system selection. It was thought that results by virtual parameter design would make it possible to decide whether to proceed to actual parameter design. When virtual parameter design was applied to a cosmetic formulation that had previously been designed by conventional methods, different evaluators assessed the formulation differently, and the results suggested that inappropriate noise factors had been used. After reconsideration of the setting of factors and the method of putting questions, a second virtual parameter design was carried out, and greater reproducibility was observed than in the first virtual parameter design. Next a confirmation experiment was performed, using actual formulations. A certain degree of reproducibility was obtained in the S/N ratio of the error variance, and it was found that an overall picture of the cosmetic had been obtained, but it was also fbund that signal and noise factors had not been distinguished.

The project reported here concerned a cleaning system for a photosensitive drum used in electrophotography. The goals were to formulate a new approach that would yield both cleaning performance and long life and, by following this approach, to obtain an excellent cleaning system. The approach taken was to use parameter design to suppress variations in blade normal force due to stickslip motion of the front edge of the cleaning blade, thereby enabling the normal force to be reduced. The input was the static blade normal force, the output was the dynamic blade normal force, and the upper and lower limits of the amplitude were taken as noise factors. Control factors such as the shape and hardness of the blade were selected and an L₁₈ experiment was carried out. As a result, parameters effective for suppressing normal force variations were found,and reduced vibration under the optimal conditions was confirmed. A 26% drop in friction also became apparent during in-system confirmation, demonstrating the effectiveness of the new approach.

Preferably, the ambient temperature of a machine tool does not vary. When there are temperature variations, the dimensional accuracy of the machining work suffers because workpieces expand or contract or the machine tool deforms. Air conditioning is required to control these conditions. The subject of the present study was a new air conditioning system installed at a machining factory. At first the air conditioning system was set to the conditions recommended by its manufacturer, but the assured temperature range under these conditions was too wide. Since the system was designed by the manufacturer,the system design could not be altered. The problem was how well the system could be optimized using conditions that could be controlled by the user. The purpose of this study was to employ conditions that the user could adjust to reduce temperature variations in the factory and run the air conditioning system efficiently. As a result of the study, optimum air conditioning settings were found, the factory temperature was kept stable throughout the year, and the air conditioning system used less power.