智能夹具用高精度夹持力传感器研究

In precision machining, the stability and reliability of workpiece clamping by machine tool fixtures directly influence the surface quality and dimensional accuracy of the machined parts. To enable online measurement of the magnitude and dynamic variations of clamping force during machining, a design and manufacturing method for an intelligent fixture with embedded clamping force sensor based on piezoresistive force-sensing chips is proposed. The intelligent fixture incorporates internally packaged clamping force sensors, which utilize the fixture's tie rod as an elastic sensitive element. Piezoresistive force-sensing chips are bonded to the tie rod to perceive the tensile force, and this tensile force is converted into clamping force according to the internal structural relationships of the intelligent fixture. Theoretical calculations and finite element simulations are employed to analyze the tie rod strength, sensor natural frequency, and the conversion relationship between clamping force and tie rod tension. Components of the intelligent fixture are manufactured, and integration of the clamping force sensor with the fixture is achieved through embedded packaging techniques. Comprehensive performance metrics of the sensor are investigated through static and dynamic performance tests. The developed clamping force sensor exhibits a linearity of -0.31% FS, hysteresis of 0.39% FS, and repeatability of 0.18% FS. Its mounted natural frequency reaches 154 Hz, corresponding to an applicable maximum machine tool spindle speed of 6 930 r/min. The developed intelligent fixture-integrated clamping force sensor demonstrates excellent static and dynamic characteristics, fulfilling the requirements for online and dynamic monitoring of workpiece clamping force in precision machining applications.