Optimization Design Of LGB680 Backhoe Loader Working Equipment

With the national infrastructure construction advancing in a large scale and the construction diversifying, multi-functional construction machinery is playing a more and more important role in construction of large-scale projects and small-scale extractive projects. Backhoe loader features loading with front part and digging with rear part, one machines can perform two modes of construction work. Changing instant working attachments will expand its functions to adapt to various works. Nowadays, backhoe loader is taking the lead among multi-functional construction machineries and it is widely used for small and medium-scale projects, such as public projects, cable placing, road building and maintenance, oil field construction, airport projects, farm and irrigation works Currently, all the domestic construction machinery manufacturers are increasing efforts of researching and developing backhoe loader to meet the market requirements. However, the domestic research level still lags behind their foreign counterpart to certain extent. In order to research and develop economical and efficient construction equipments and improve technical performance of backhoe loader, it is necessary to calculate and analyze the structure and movement process of its work equipments, this will provide theoretical and technical support for designing.Loading equipment is one of important parts of backhoe loader, its performance has an direct effect on the performance of the machine. Analyzing and optimizing this work equipment can improve the design and manufacturing level and productivity, it can also make better use of its power and improve working conditions. This article takes the work equipments of LGB680 backhoe loader manufactured by Shandong Lingong Construction Machinery Co., Ltd as antetype. Based on plenty of research on its structure and use, analytic models are established for loading equipment. This article analyzes its structure characteristics and kinematics characteristics; and discusses the main technical parameters of its performance; and analyzes possible interposition when working, which provide reference for improvements. Three aspects of work are done as follows:(1) Mechanism and dynamics analyses were performed on the loading working device eight-link parallel mechanism based on the professional knowledge, analytical model for the loading working device of backhoe loader LGB680 was set up; the required external applied load for dynamics analysis was determined; the overall parameters and performance parameters such as breakout force and etc. were also analyzed; dynamic simulation was conducted, and translational property, transmission ratio, transmission angle were analyzed; the possible structure and movement interference were analyzed; the objective function and constraint function required in the optimization process were determined; the possible mechanism and movement interference situations occurred during the movement process were analyzed.(2) Mechanism optimization analysis was performed on the loading working device of the backhoe loader from a new perspective, through the establishment of optimal model, the definition of parameter point, the setup of parameter values and the establishment of constraint and driving functions, the objective and constraint functions were determined. Mechanism optimization analysis was carried out via multi-body dynamics simulation software RecurDyn/AutoDesign toolbox, and a mechanism model with superior performance to the existing one was obtained. By comparing the various optimized performance induces with the former one, we can see that the performance of the new mechanism is more competitive, which provides reference data for further upgrading the design level in the future.(3) use the GM finite element analysis software Ansys Workbench to analysis the wheel loader working equipments through solid modeling and static finite element, to calculate the stress and straining in the working condition, and analysis the distribution of the dangerous cross-section and the high-stress zone . Find out the stress center and easy broken zone, to take measure to improve. We can see from the calculation results, when the machine in working mood, the distribution zones of stress is the same for the two lift arms: upper surface is pulled, and the under surface is pressed. In the side loading working conditions, the stress distribution zones for two life arms are different. For the weighted side life arm, the upper surface is pulled, and the under surface is pressed. But it is opposite for the other lift arm. Because most load weight is borne by left lift arm, so in the side loading working conditions, the stress is much higher. Overall, it is not big stress for lift arms, in all working conditions, the max stress should lower than material allowed stress, should have enough stress stock, and percent of max stress zone should be larger, to compare with the low stress zone, so the structure can be improved, decrease the weight, improve the performance. The rules of straining and stress are quite same. Affected by the two kinds loading ways, the max straining zone is on the rear rocker arm when side loading. For the two loading ways, the rear pull rod used 110mm wide, 30mm thick steel plate in original design, it is safer, so it can be reduced to lower the cost.Through the analysis for the dynamics, structure improving and intensity of the LGB680 backhoe loader's working equipments, we get the better capability structure model in this thesis. If this design can be carried out, it can make good sense for improve the backhoe loader's market competitive strength, backhoe loader's production line, and also is favor of developing the competitive backhoe loaders.