Objective

Wireless integration of radio sensors in a grinding spindle of a machine tool to measure vibrations and forces occurring during the grinding process.

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Client

Institute of Production Engineering and Machine Tools, Leibniz University Hannover

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Project period

2021 / 2022

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Challenges

• Extremely small installation space (30 x 5 x 5-8,5) mm
• Battery charging without retooling the machine
• Resistance of electronics to high temperatures (85°C)
• Wireless data transmission from the inside of the machine / through the seal
• Electromagnetic interference from the additional eroding process and the spindle drive

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Realization

• Integration of a wireless measuring system in four tiny recesses of a grinding spindle
• Development of a board for data acquisition (DAQ) and data transmission with integrated MEMS 6-DoF-IMU for the measurement of accelerations, rotation rates and temperature (16 bits, up to 6,5 kHz sampling rate) as well as for the connection of 4 semiconductor strain gauge full bridges (24 bits, up to 1,5 kHz sampling rate)
• Development of a power management board for connection of the rechargeable battery
• At downtime of the machine: autonomous connection of a voltage source via a stylus for charging the Li-Ion battery with high charging power (2 minutes battery charging for 8 minutes runtime, max. 80 minutes)
• Wireless data transmission via board-integrated antenna per 2.4 GHz radio link to a nemi Connect receiver module

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Advantages

• Structure-integrated measurement of condition data of an autonomous machine tool
• Mapping of sensitive properties by integrated sensors in the machine tool
• Reliable wireless data transmission even through seal and housing of the machine tool
• Energy supply concept suitable for series production
• Autonomous, fast battery charging during short machine downtimes
• High measurement data quality / low noise due to energy supply via rechargeable battery

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Deployed nemione^® products

• nemi Connect