Tanaka Hidetake

To fulfill user requirements, various products are manufactured using machine tools requiring high-cutting-speed technology. The development of these products typically requires high-precision and high-efficiency machine tools. However, large centrifugal forces affect the tool gripping precision and rigidity during high-speed rotation. Recently, various tool holders have been developed to solve these problems. However, evaluation methods for tool holders vary by manufacturer, thus rendering it difficult for users to perform quantitative assessments. Therefore, a device is developed in this study that can measure the gripping properties of a tool holder to enable quantitative evaluation. The proposed gripping-strain measurement tool can measure the gripping force of a tool holder using strain gauges. Using a wireless strain logger as a sensor module and strain gauges attached to the tool shank, this device can measure the gripping force exerted from the tool holder and wirelessly transfer the recorded data to a computer for analysis. Unlike previously developed devices, this measurement device can simultaneously measure multiple positions of gripping strain. To validate the feasibility of the newly designed gripping-strain measurement tool, gripping-force distribution measurements are performed using commercial tool holders. The developed gripping-strain measurement tool is tested statically and dynamically using a machine-tool spindle system. The results show that the developed test tool can effectively measure the gripping-strain distribution. Additionally, the feasibility of the developed tool for strain-transition measurement during spindle rotation is validated.

The authors have proposed inclined planetary machining for drilling CFRP, which can produce higher-quality holes than conventional drills and helical machining. A portable inclined planetary machining device has been developed. Conventional inclined planetary machining devices were designed to incline the entire tool spindle and required manual adjustment. In this study, the tool tilting mechanism was automated, and a structure was created in which only the tool part could be tilted, thereby reducing vibration. The device design and mechanism were verified in this report.

Carbon fiber-reinforced resin (CFRP) is a difficult-to-cut material and is prone to burrs and surface delamination. We propose inclined planetary machining as a high-quality drilling method for CFRP. Inclined planetary machining is a method of drilling holes by inclining the tool and using precession motion, which is effective in suppressing burrs and surface delamination. It has also been shown that the quality of machined holes can be improved by using a geometric radius end mill. Here, we applied a radius end mill to inclined planetary machining to conduct continuous hole machining experiments in CFRP, and discuss the progress of tool wear and the quality of the machined holes. In addition, the influence of inclined planetary machining conditions on the machined hole quality was determined by analysis of variance.