Research On Structure Optimization And Control Technology Of Large Hydraulic Vibration Hammer

As one of the most important pile workingmachines in pile foundation construction,hydraulic vibration hammer has the characteristics of high efficiency,strong applicability and small noise pollution.But with the development of modern construction industry,the traditional hydraulic vibration hammer in the pile driving process and control performance also exposed many problems,the domestic vibration hammer design theory is backward,the level of hydraulic control technology is low,the function is generally single.For this reason,starting from the study of the theoretical mechanism of hydraulic vibration hammer,this paper optimized its structure and hydraulic control system,and provided a new research direction for the development of pile machinery industry.This paper first explored the mechanism of hydraulic vibration hammer vibration pile sinking process,studied the principle of pile sinking,mechanical analysis and calculation of the pile load.Based on the linear vibration pile driving theory,a two-degree-of-freedom mathematical model of the vibration system was established,and the differential equations of vibration mechanics were obtained by Lagrange energy parameter method.The system was simplified and relevant parameters were substituted to solve the first-order and second-order natural frequencies.The Solidworks software was used to build the simplified model of the vibration hammer box structure.Then the prestressed modal analysis was carried out by ANSYS Workbench software to obtain the first ten natural frequencies and vibration shapes of the box.And then the displacement response of each surface of the box under the harmonic excitation of different frequencies was analyzed by the harmonic response.According to the simulation results and the mechanical design theory,the optimal design scheme of the box structure was proposed under the condition of meeting the strength requirements,and the modal simulation of the improved model was carried out to analyze the harmonious response.The first and second order natural frequencies of the optimized model are increased by 41.64% and 51.62%,respectively.The displacement responses of the top,side and bottom are reduced by 70.20%,46.08% and 38.33%.Aiming at the problem of resonance in the starting process of hydraulic vibration hammer,the hydraulic control system was optimized,and the control scheme of hydraulic soft starting was proposed according to the principle of soft starting.Lab VIEW software was used to program the control signal to extend the starting time of the vibration hammer and reduce the energy fluctuation caused by hydraulic impact.The control system hardware composed of computer,data acquisition card and signal converter.Through comparative experiments,the feasibility of the hydraulic soft starting control scheme to reduce the starting resonance was verified,and the conclusion was drawn that the control effect was the best when the starting time was 15 s.In order to improve the synchronous motion precision of double motor drive,this paper proposed the adaptive parameter tuning PID control strategy based on BP neural network according to the principle of neural network and PID control thought.We established the mathematical model of the hydraulic transmission system,and verified the feasibility of BP neural network PID control strategy through Simulink simulation.According to the actual situation,the control system based on STM32 microprocessor was built,and the experimental results show that the maximum synchronization speed error decreases by 42.48% after the control.