In the injection molding process, demolding is the final step, and if issues arise in this step, the quality of the molded product will deteriorate significantly. Although many researches have been performed thus far regarding the demolding phenomenon, the detailed process of the transition of demolding force has not been discussed. In this study, a monitoring system for examining the demolding phenomenon in detail has been developed for injection molding using a stripper plate type ejection. Firstly, the configuration of the developed monitoring system is described, and subsequently the observed results of the demolding phenomenon are shown and discussed. In addition, the cause of the measured force signal is discussed based on the experimentally results of simultaneous measurement with the force sensor and the acceleration sensor, and a mathematical model for the force signal is proposed.

We have developed many computer-assisted instruction (CAI) systems for design drawing education, and we have reported their effectiveness. In recent years, on-line learning systems using the internet have been used to teach subjects in which specialized tools are not used, such as mathematics and English. However, design drawing education generally uses specialized tools (3D-CAD systems). Therefore, we have developed an on-line learning system for design drawing teaching materials using the internet. A question considered while developing this system is “What is the teaching materials students would like to learn?”. We thought that it was important for students to enjoy learning through the system and to follow the progress of their learning. The on-line learning system was used continuously, and we observed good educational results. This paper describes the online learning system and its effectiveness for design drawing education.

This paper discusses the assembly variation that can arise when the positioning between two parts is constrained using two holes that fit over two bosses. Two parts positioned using two holes fitting over two bosses may move relative to each other during assembly because of slight clearances between the boss-hole pairs. In many cases, two boss-hole clearances are toleranced equally, resulting a motion which is more complex than simple translation or rotation. This paper describes the relative motion between the parts using a concept called the "motion area." When the assembly is defined with nominal inter-boss distance of L and boss-hole clearances of 2δ, for any point (X, Y ) in the boss part, the limits of the motion area in the hole part’s coordinate system are given by x_limit = 2 δ (2Y/L sin θ + cos θ ), (θ = |tan^-1(2Y/L)|), y_limit = 2 δ (0 ≦X ≦L), y = 2δ (2X / L −1), (X ＜0, X ＞L). This paper presents a tolerance analysis application using the above.