Study On Mini Excavator

In the world engineering machine market, mini-excavator is one of engineering machine products which have the largest produce and sale quantity. Mini-excavators are mainly used in the following occasions: highway maintenance, park and garden forestation, subzone construction, city planning and agricultural built, etc. And it has strong mobile performance and small dimensions, which make it met the case having dispersive earthwork and narrow working space. At present, basic establishment is carrying on all-around in our country, so the market of mini-excavator is expending and the demand is growing very fast. Therefore the theory research relating to practice has important operation significance and long-term direction significance. There are still many differences between the homemade mini-excavators and the overseas, which are mainly incarnated as complete machine matching, microoperation performance, maintainability, and reliability and appearance quality. The homemade product has advantages in price and service. The overseas mini-excavators are developing towards perfect appearance, high reliability, and convenience and comfortable in operating. Now the homemade mini-excavators are developing towards multifunction, intelligence, energy saving, high reliability, humanized design and automatic supervisory control. Based on the research and development, design, manufacture and of the HE39 , this paper do some research on mini-excavator.. The primary structure of HE39 is composed of work device, revolving dial and chassis. The work device is articulated with the frontend of the revolving dial by swaying head. The revolving dial and the chassis are coupled by revolving bearing. The engine is post positioned on the revolving dial. The drivers cabin is situated at the left frontal corner of the revolving dial. The bulldozer shovel is installed on the frontend of chassis. The rubber pedrail is installed on the travel gallows. The transmission agent is a total power controlled hydraulic system whose manipulate mode is the type of entire hydraulic forerunner. Its electric appliance system has the function of start, lighting, monitor and control and automatic alarm. Considered the digging parameter, HE39 gives prominence to the digging depth, which satisfies the demand of home market user. The design of digging parameter refers to many factors, for example digging force, back balance, tread, chassis width and the self constraint condition of work device. After computed the total travel theoretical digging force, we get the changing curve which is accord with the demand of operating mode. The maximum digging force which can be optimized based on design needs relates to the system pressure, cylinder diameter of scoop arm and each the arm force of linkage point. In most conditions, the system pressure and the cylinder diameter hasn't much difference, so the design of linkage point is the most important factor to the theoretical digging force and the changing curve. The moving arm and scoop arm of HE39 is trunk structure girder. When optimizing, obtaining best performance with less mass and higher reliability should be the goal. At present, the finite element method is effective method to study girder structure, which base on elasticity mechanics. For the working device of excavator consisted of many girders, it is reasonable to choose girder unit model, and find out the displacement of crunode. According to the content mentioned above, static analysis can be finished. Since the working device is a interspaced lever structure, and the applying force on it is changing along with time, it is necessary to analyze it as a elastic structure in a motion cycle. So the actual motion analysis is more complex than static structure one and the research must be based on dynamics.The main contents of hydraulic system analysis are: the analyses of the transient state pressure and its fluctuation in the high pressure system, seeking the response speed of the control mechanism and actuator (such as hydrauli...