This study clarifies the relationship between cutting conditions and residual strain in ultrasonic vibration cutting (UVC) performed in the thrust direction. Focus is placed on the working relief angle θw -defined as the difference between the tool relief angle and the tangent of the tool motion trajectory- as a key indicator of geometric interference between the tool relief face and the machined surface. Experimental results revealed that subsurface hardness increased with increasing θw. When the difference in θw was approximately 1°, similar hardness values were obtained regardless of cutting speed. Under interference-free conditions, the hardness remained comparable to that produced by ordinary cutting. Finite element analysis further showed that the plastically strained region enlarged with increasing θw, consistent with the observed hardness distribution. Moreover, stress fluctuation analysis during the ultrasonic cycle showed that geometric interference induced localized surface compression by the tool relief face, thereby generating compressive stresses. Tool-wear measurements indicated that wear width under low-interference conditions was similar to that in ordinary cutting, while under high-interference conditions it increased 1.4 times; however, both levels remained within practical limits. These results show that controlling interference and θw enables selective regulation of the occurrence and magnitude of residual stresses.

This study aims to develop a self-;actuated ultrasonic grinding wheel that enables ultrasonic vibration grinding to be performed on general-;purpose machine tools without the need for dedicated machines. The developed grinding wheel is designed to incorporate a piezoelectric actuator for vibration excitation, a leaf-;spring structure to prevent the transmission of ultrasonic vibration to the wheel mounting hole in the flange, and an integrated power supply system. As a result, the following achievements were obtained: (1) The basic structure of a self-;actuated ultrasonic grinding wheel was investigated, and design guidelines for each constituent element were established. (2) A prototype ultrasonic grinding wheel was fabricated, which exhibits axisymmetric radial vibration at a frequency of 42.7 kHz with an amplitude of 3.5 µm. (3) Grinding experiments on single-;crystal SiC wafers were conducted using the prototype wheel, demonstrating improvements in both surface quality and grinding efficiency, thereby clarifying the effectiveness of the developed self-;actuated ultrasonic grinding wheel. The results of this study are expected to contribute to the widespread adoption of ultrasonic vibration grinding and to the high-;efficiency, high-;precision grinding of hard and brittle materials.

High-precision metrology is essential in manufacturing, as reliable fabrication requires accurate measurement. In optical systems, the surface figure accuracy and surface roughness of lenses and mirrors have a strong impact on optical performance, driving continuous advances in shape measurement techniques. Among optical components, X-ray mirrors used for focusing and imaging require particularly high accuracy. While nanometer-scale fabrication and interferometric measurement techniques have been established for planar and near-spherical aspherical mirrors, accurate measurement of the inner surfaces of tubular mirrors remains challenging. This paper presents a non-contact shape measurement method for the inner surface of Wolter mirrors, which have a rotationally symmetric tubular geometry composed of ellipsoidal and hyperboloidal surfaces and are used in X-ray telescopes such as the Focusing Optics X-ray Solar Imager (FOXSI). The measurement system combines a roundness measuring instrument equipped with an air-bearing rotary stage and a motion error compensation technique. A fork-shaped jig holding laser displacement sensors was newly designed to enable axial scanning inside the mirror, while reference mirrors were simultaneously measured to suppress motion errors of the scanning stage. Using the developed system, non-contact measurements of both axial and circumferential shape profiles of Wolter mirror inner surfaces were achieved. Measurement repeatability of approximately 1 nm RMS in both axial and circumferential directions was confirmed through repeated measurements using a flat reference mirror to evaluate intrinsic system performance, as well as repeated measurements of a Wolter mirror.

Sliding headstock automatic lathes allow a workpiece to move in Z-axis while a tool remains stationary to machine tiny parts in a short cycle time. They have usually two turning spindles opposing each other with plural turrets and deliver the workpiece between the spindles sequentially in front and back parallel machining. However, with the changes in the production of small quantities of many types of parts, the preparation for a machining process occupies a high ratio of production lead times. It is thus expected that the achievement of computer-aided process planning (CAPP) could shorten the preparation time for realizing highly efficient parts machining. Therefore, a CAPP system has been developed by recognizing machining features in previous studies, is reconfigured to match with the characteristics of sliding headstock automatic lathes. The reconfigured CAPP system calculates a machining process that removes material in the order of distance from the ends of a workpiece. Machining operations conducted in parallel by each turning spindle are allocated based on the estimated machining time to reduce the wait of turning spindles. A case study shows usefulness to promptly start parts machining by means of a sliding headstock automatic lathe with the reconfigured CAPP system.