In metal forming, it is important to acquire detailed information on deformation, strain, and stress that occurs in tools and dies in order to perform excellent process design. In this paper, a capacitive displacement transducer is combined with the strain gauge method for measuring the elastic deformation of a tool-workpiece interface 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. Displacement of detective pin is measured by gap-type capacitive transducer. The displacement of the capacitive transducer is simultaneously measured by the strain gauge method for adjusting the measurement obtained from the capacitive transducer. This combined technique was applied to measure die deformation in the backward extrusion of pure aluminum. The measurement was made at 8 points in height direction simultaneously and the displacement distribution over the die-workpiece interface was obtained. We discussed the reliability of the measurement and demonstrated that the proposed method is useful for measuring die deformation in forging.

In this study, we aim to develop self-adhesive gears made of 100 % bamboo fibers without any chemical treatment. In the molding of 100% bamboo fiber, lignin contained in parenchyma cells around the fiber reacts during heating and pressurization to form self-adhesive gears. In our previous research, we developed parallel shaft spur gears. Compared to spur gears, which have a two-dimensional shape, bevel gears have a three-dimensional shape and are complex, making it difficult to evaluate the meshing state during drive. In a previous study, it was clarified that the meshing transmission is established by monitoring the tooth root strain, and that the Young's modulus of bamboo fiber is small and mutual interference of tooth root strain is likely to occur between adjacent teeth. In this paper, the relationship between the outer end plate and tooth root strain is discussed using experiments and finite element analysis.