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.

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