Hydraulic Excavator Working Device Dynamics Studies

As a fundamental machinery of earthwork digging, the performance of itsequipment is directly related to productivity, energy consumption andreliability. Therefore, it's necessary to improve the overall performance of theexcavator by introduction of advanced design theories and methods. Under thisbackground, this thesis does simulation study to dynamic characteristics of amedium-sized backhoe hydraulic excavator's equipment which is selected asresearch object. The contents of the thesis are as follows:(1) The paper gives a brief review of development status of excavatorindustry and research situation both home and abroad, then, focuses onanalysis of existing problems in actual use as well as countermeasures ofexcavator's equipment; subsequently, introduces structure features of theworking device and gives detailed analysis to typical operating conditions.(2) Firstly, the dynamic theory of multibody system are presented.Secondly,kinematic and dynamic models of equipment are established bymethods of D-H homogeneous transfer matrix and Newton-Euler respectively.Finally, idealized digging force,excavating resistance and the theoreticalmining force by arm digging method are analysised. All of these buildfoundation for the following virtual prototype simulation.(3) Design principles and ascertain of structure scheme of backhoeworking device are outlined, at the same time, the introduction of T-D designmethod and realization approaches are also presented. According to the actualstructure dimensions of a medium-sized excavator, the3D model of equipmentwas built with T-D design method based on PROE. This design approachprovides a high efficient modeling method for modification and productseriation of excavator.(4) After the3D model of equipment was imported into ADAMS byinterface software MECH/PRO, the paper does kinematics and dynamicssimulation systematically. First, the whole operating range are obtained by draw envelope diagram. Comparative analysis of the pros and cons betweentwo design schemes are got by change the model's parameters. Second, Thewhole theoretical digging force of some working conditions by two excavatemethods of bucket and arm dig are gained as well as limiting factor ofmaximum digging force in the working condition.(5) Using different drive modes to two excavate methods respectively, theforce curve of imprtant joints within an operating cycle are attained, revalingoperating performance and dynamic characteristics in the typical operatingconditions of the backhoe device. Then, combined with the failure formats ofexcavator components, the thesis comes to conclusions by analyze simulationresults, providing theoretical guidance for the design and operation in actualuse of the working device.