This paper describes a laser-hardening technique using a top hat-shaped rectangular laser beam to form a uniform hardened area including the inner and outer corner parts. Experiments were carried out using a simple shaped workpiece with a square step cross-section. The influences of laser irradiation conditions on laser-hardening characteristics were evaluated by both experimental and theoretical approaches. A simple laser irradiation method to make a uniform hardening area was found.

This study focused on an ultrasonic assisted machining method for high-precision hole processing in glass materials. To elucidate the machining phenomena peculiar to this method, tool behavior analysis at the start of drilling using a high-speed camera and surface roughness of the inner surface of the hole were examined. The results indicated that the helical shape is due to the centripetal action at the tip of the drill and brittle fracture of the work material. We propose a method to calculate the theoretical surface roughness from a computer simulation model of the surface properties when this method is used. Comparison of the estimated values and values measured using this method indicated that the tendency of surface roughness almost matched.

The polishing characteristics of cylinder inner surface polishing utilizing magnetic compound fluid were investigated. Coaxial polishing and helical polishing are proposed. Therefore, the performance with regard to material removal, surface accuracy, and shape accuracy were clarified. The results of polishing methods suggested that there is an optimum polishing speed. In addition, coaxial polishing showed improved performance with regard to material removal, surface accuracy, and circularity. On the other hand, helical polishing showed significant performance for corner shape (in/out) accuracy, and both polishing methods improved cylindricity.