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Study of piezoelectric six-dimensional force sensors for small working spaces

Study of piezoelectric six-dimensional force sensors for small working spaces

(Summary description)The safety and economy of rocket launches are closely related to the precision machining of the fuel tank grids.

Study of piezoelectric six-dimensional force sensors for small working spaces

(Summary description)The safety and economy of rocket launches are closely related to the precision machining of the fuel tank grids.

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The safety and economy of rocket launches are closely related to the precision machining of the fuel tank grids.

小工作空间压电式六维力传感器研究

With the advantages of high efficiency, high versatility and high accuracy, mirror milling has become an effective way to solve the processing problems of large thin-walled components. To ensure the machining accuracy of mirror milling, the information of multidimensional forces and moments on the support end should be accurately obtained and the small changes of the support force should be sensed sensitively, so that the position of the support end and the size of the support force can be adjusted in real time to provide stiffness compensation for the local machining area.

 

Obviously, the real-time measurement of the support force signal is an important guarantee for the reliable operation of rocket storage box barrel segment raster mirror processing and equipment. In addition, the support end requires a high degree of integration, the force sensor unit is limited to Ф17mm in a small working space. Support force signal is obtained by the force sensor, so the development of a small working space for multi-dimensional support force measurement of the sensor, and its accurate calibration is to ensure the accuracy of the bulkhead grid processing basis.

 

A solution is proposed to develop a highly sensitive piezoelectric force sensor for six-dimensional support force measurement in a small working space. In this paper, we take the support force signal measurement as the research object, and analyze and study the difficulties of the support force test from the aspects of test principle, theoretical derivation, structural simulation and experimental calibration, in view of the difficulties of the space-constrained, multidimensional and low-resolution support force signal measurement.

 

Firstly, we summarize the difficulties of the support force signal testing based on the force situation of the support end in operation. By using the stress distribution law of the piezoelectric wafer under the action of six-dimensional force, the correspondence between the induced charge and the six-dimensional stress is found, and the combination of crystal group and electrode sheet is obtained to realize the measurement of the six-dimensional support force in a small working space. After that, the structure of the piezoelectric force sensor crystal group and the housing is designed. The preload form of the force transducer in the small working space is determined, the mechanical model of the transducer in the preload condition is established, the force transmission process on the transducer is analyzed, and the permissible range of the preload component stiffness in different ranges is obtained.

 

The simulation modeling of the sensor was carried out by ANSYS Workbench software, and the modal and static structural analyses of the sensor were carried out respectively, and the results met the measurement requirements of the support force in the mirror milling process. According to the factors influencing the resolution of the test system, the components of the signal acquisition system were selected reasonably, and the force test system was built.

 

Finally, the calibration experiments of the developed piezoelectric force transducer were conducted to obtain the static and dynamic calibration indexes of the force transducer. The influence factors on the static calibration index are analyzed, with emphasis on the influence of bias load on the inter-directional interference, and a method of discriminating the degree of deviation of the loading point is proposed. In view of the unavoidable fact that the mechanical connection is biased, the output proportional normalization method is proposed to overcome the influence of bias on the normalization coefficient, and the maximum inter-directional interference is reduced to within 5%. After that, a resolution test was conducted on the force sensor, and the experimental results showed that the developed piezoelectric six-dimensional force sensor meets the requirements of support force measurement.

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