A measurement method by the combination of a gap-type capacitive displacement transducer and the strain gauge method is applied for measuring the elastic deformation of inner surface of die in cold forging. A 1-mm-diameter hole is bored radially to the depth of about 1.2 mm from the inside surface of a die container and a steel pin is placed in the hole for detecting radial displacements near the die-workpiece interface. The coil spring pushes the detection pin inward in the radial direction, while the radial displacement of the die-workpiece interface pushes it outward. The detection pin head faces the capacitive transducer head for measuring variations in the gap between the head of the detection pin and the capacitive transducer head. The radial displacement of the capacitive transducer head is simultaneously measured by the strain gauge method for adjusting the measurement obtained from the capacitive transducer. This combined technique is applied to measure die deformation in the backward extrusion of pure aluminum. The measurement is made at 8 points in height direction simultaneously and the displacement distribution over the die-workpiece interface is obtained. We make measurement under various die/punch shapes and configurations. In conclusion, we demonstrate the validity of this measurement method.

When torque characteristics of a grease-lubricated small ball bearing, 608, were experimentally checked, the results showed that even bearings from the same manufacturer had large variations in torque, and that the torque did not converge even after 24 hours at low rotational speed. However, after the experiment, the internal grease was washed away, and the torque was measured using the same bearing with a small amount of oil for lubrication, the torque was low and no variations or fluctuations were not observed. The reason why there were torque variations, even though the amount of grease sealed was almost the same, was thought to be due to the state of grease filling. Therefore, in this study, torque in a small ball bearing 6204, was measured with different state of grease filling using a device that can fill a fixed amount of grease into a targeted position. Then, the effect of the initial state of grease filling to the torque was clarified.

We report a case of mechanical design education at National Institute of Technology (KOSEN), Maizuru College. In this case, students proposed products in cooperation with a local company. The theme is to invent “a device that makes people and society happy” using products related to Tsubakimoto Chain Co. This educational program began in 2017, and contests have been held every year. We describe a follow-up report on the educational program including Project-based learning (PBL). First, we introduce the content and schedule of this subject. Next, we describe the class flow and show evaluation items for presentations. We introduce a list of products that won the best award. Then, we explain how to produce ideas to create products. Finally, we describe a questionnaire on class activities. The results of the questionnaire showed as follows: 1) The improvement is seen in terms of independence, innovation and class hours. 2) The factors contributing to the improvement of teamwork ability are not clearly understood, so continued research is needed.