| Jacquard needle selecting device is a needle selection, it is used to control the compilation of warp and weft, to produce different patterns and different density of cloth, the core component of the jacquard loom, directly determines the performance of the jacquard machine. The existing needle selection device is an electronic needle selector, and they are mainly divided into two types: a piezoelectric type selector and an electromagnetic needle selector. Two kinds of structures are used to make electromagnetic coil generates a magnetic adsorption force and piezoelectric ceramic change toggle needle selection is achieved purpose pin respectively. The performance has been greatly improved, compared with the electromagnetic needle selector. Piezoelectric selected needle is the key component for piezoelectric actuator, the existing piezoelectric actuator due to small displacement, the driving voltage is large and using the positioning mechanism, these institutions will influence the reliability and service span of needle detector.The key component of the piezoelectric needle selector is a piezoelectric cantilever actuator, which is a device that can be converted to mechanical energy by the inverse piezoelectric effect of piezoelectric material. Because of the small displacement, the drive voltage of the current selector is larger, and some positioning mechanisms are used which will affect the life and reliability of the needle selector.In order to improve the performance of the piezoelectric actuator(The following are called pre loaded piezoelectric cantilever actuators), a new type of piezoelectric actuator is designed and analyzed in this paper. Through the optimization and innovation of the traditional piezoelectric cantilever beam, pre-loaded in the direction of its length, so that it can be transformed into a special nonlinear device. When the piezoelectric cantilever is working, the input energy can be output to the maximum extent, so as to improve the output displacement, reduce the working voltage and prolong the life of the actuator.The work of this paper is as follows:1. In search of theoretical support, the system uses the Euler Bernoulli beam theory, the Hamilton principle and the Euler Lagrange equation to establish the energy function, and the dynamic equations are derived, and the mathematical model is established.2. According to the established mathematical model, using MATLAB numerical simulation, obtain the relation to piezoelectric displacement of the free end of the cantilever beam with pre-loaded, voltage and preload, and draw the curve. To find the best matching, and the theory of maximum amplitude. 3. Making experiment device of pre-loaded piezoelectric cantilever actuators, by a digital micrometer to test the precise control of pre-loaded, using laser micrometer to measure the displacement of the free end. By a digital micrometer to complete the precise control of preload, the optimal preload and the maximum amplitude of the mathematical model are verified. In the end, the preload is 0.09 mm and the driving voltage is 10 V, the maximum displacement of the pre loaded piezoelectric cantilever actuator is 0.17 mm. Compared with the traditional piezoelectric cantilever actuator, a new type of pre loaded piezoelectric cantilever beam actuator is 5 times as much as the displacement magnification.Through the above theoretical analysis and experimental test and verify the proposed pre loaded piezoelectric cantilever actuators is meaningful new type piezoelectric actuator, the maximum displacement and the traditional piezoelectric cantilever actuators compared to amplify 5 times. By reducing the driving voltage, the service life can be greatly improved, with the advantages of compact structure and high reliability. And this method has universal significance, can be applied to other needs of low frequency, large displacement of the piezoelectric device. |
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