| Construction machinery is the most common type of machinery in the field of engineering construction, including loaders, excavators, bulldozers, etc., which are widely used in farmland, water conservancy, municipal, transportation and other construction fields. With the transformation of economic development model and the continuous advancement of urbanization, the construction demands of the municipal engineering, pavement maintenance, district cleaning in the crowded area are growing. With the growing awareness of environmental protection and the increasing demand of miniaturization of construction, traditional engineering machinery has become increasingly difficult to meet the needs of market today because of these problems such as its high energy consumption, noise, emissions and maintenance, etc.The implementation of "NC generation" innovation engineering equipment offers a great opportunity for traditional construction machinery technology to upgrade. Controllable mechanism is an integrated product combining the control technology, electric drive technology with the traditional institutions. It not only effectively solved the problems of the traditional mechanism such as the lack of flexibility, and the difficulty to control the movement law, etc. With the advantages of high efficiency, low noise, higher reliability and intelligent level, the controllable mechanism has become one of the hottest research fields of mechanism. Up to now, a great number of scholars at home and abroad have done a lot of researches on controllable mechanism, but they mainly focus on the theoretical aspects and the research results are difficult to be transformed into engineering application, only applied to a few fields such as controllable press and parallel robot platform, etc.The theoretical and application research of controlled mechanism type engineering machinery not only plays an important role in solving the problems of traditional engineering mechanical such as, energy consumption, noise, and exhausts pollution, etc. and also has great significance in improving the reliability of construction machinery and intelligent level, helping domestic small construction machinery to become more competitive in market. In recent years, although our research team did some research on the controllable mechanism type engineering machinery, there still exist some problems because the actuator design are separated from the engineering practice, such as the configuration design is unreasonable, Kinematics statement is not accurate, without study on dimensional synthesis and dynamic optimization research, simulation analysis out of performance indicators, the implementation of institutions can not meet the requirements of engineering mechanical performance.In view of the problems above, taking loader as research object, a new kind of controllable loading mechanism is proposed in this thesis. What’s more, the relevant loading mechanism design theory and research methods meeting the requirements of loader function will be studied. In addition, application of controlled loading mechanism will also be researched. The main work and innovation are as follows:(1) Based on topology theory, for the study of configuration synthesis of controllable mechanical engineering machinery, a new configuration synthesis methord which basid on the functional point judgment and meet functional was put forward. Using this method, the comprehensive and systematic configuration of the controllable loading mechanism is studied.Based on the analysis of the existing loading mechanism, topology requirements of controllable load mechanism are determined and obtained bar component matching scheme. Using interpolation point method in embryo obtains all kinds of topology graph which meet the requirements of topological structure. According to the design requirements and functional characteristics of the controllable actuator determine the existence condition of functional components, and all feasible specific programs which each topological graph correspond and meet the functional requirements are obtained through the judgement of the function point. According to the optimization criterion, the feasible scheme of the topological map is optimized, and the topology graph is transformed into a loading mechanism according to the specific code, and the 11 best configurations are obtained. Through the studied on the controllable mechanism type construction machinery through this topology synthesis method, get a lot of new configuration, application and obtain a number of inventions patents.(2) Based on the metamorphic principle, variable cellular method is proposed according to controllable mechanism engineering machinery.Introduce the kinematic accessory locking device, the configurations of mechanism and degree of freedom can be changed by timely change the quantity of kinematic pairs in order to achieve different institutions structure transitions between states, meet the functional requirements of the various stages of work, by putting this method into application to controllable loading mechanism field can effectively reduces the number of active rod, thereby reducing the driving element quantity, reduces the cost.(3) In view of controllable mechanical engineering machinery, the general method of kinematic analysis based on performance requirements is studied. Using this method, the kinematics, inverse problem solving, singularity analysis and kinematic scale synthesis of the controllable loading mechanism are studied.Using the Newton-Raphson approach, the kinematics model of controllable loading mechanisms about positive solution and inverse solution is established. Based on kinematics Jacobian matrix to solve the controllable loading mechanism of forward and inverse kinematic singularity, and the 16 kinds of exotic structures which including linear structure and triangle singularity structure of controllable loading mechanism are obtained. Based on loader performance’s requirements, the dimensional synthesis researches on controllable loading mechanism’s bucket, moving arm lift branched chain and bucket turnover branched chain are conducted. Finally, a group of feasible scale parameters that accord with requirements of controllable loading mechanism design are gained.(4) A dynamic scale optimization method is studied for the controllable mechanism of engineering machinery.According to the characteristics of the mechanical operation of the controllable mechanism, the dynamic inverse problem is solved by using the dynamic static method, and the constraint reaction force and the driving torque are obtained. Established the actuator dynamics scale optimization model which choose the minimum of the maximum driving torque of the actuator under a certain condition as the optimization objective function and choose singularity, transmission angle etc as the constraint conditions. In the end, the optimization model is solved by using the complex method and penalty function method, and obatained the optimal size parameters of the actuator.Using this method, the dynamic scale optimization is carried out for the boom and arm lifting of the controllable load mechanism, and makes the maximum load torque of the first active rod in the upper limit lifting condition reduced by 11%, and in the upper bound discharge condition the load torque is reduced by 80%, and effectively improve the mechanical properties of controllable loading mechanism.(5) Based on the above analysis, the virtual simulation, structure analysis and prototype experiment of the controllable loading mechanism are carried out based on the performance index of the loader.According to the performance index of loader and the design requirements of controllable loading mechanism, the virtual simulation of the controllable loading mechanism is carried out, and the simulation results show that the movable arm swinging angle, unload bucket angle and unloading height and other key performance parameters meet design requirements. The stress and strain distribution of each component is obtained by finite element analysis of the specific conditions and attitude. In the end, the first full-size controllable mechanism loader is developed, and the load lifting experiment is carried out. Compared with the traditional loading machine, the new type of controllable structure loader is a new type of engineering machinery which very suitable for small loaders with low energy consumption, zero emission, low noise, high reliability, etc. |
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