| In the mining of open pit, the large mechanical excavators are widely used. Since the domestic demand for mechanical excavators is large, under the support of a united project with China First Heavy Industries, the major excavation sector-working device-of the large mechanical excavator was analyzed in detail. The main research includes:1. The analysis of mining trace and mining resistance.In similar working condition, the traces of bucket tooth differ. Thus, the resistances from the earth differ, and then the work done by excavator is not the same. The chose of mining trace will directly affect the energy consumed by the working device. To ensure the minimization of the mining resistance, the digging trace of the same horn——equation of logarithmic spiral trajectory was raised, so was some primary problems which are related to the mining trace, such as mining volume calculation, initial mining angle and final mining angle, the maximum mining depth during the mining process. The mining resistance was analyzed and a comprehensive resistance formula which could reflect the mining properties was determined.2. Kinematics analysis of working device mechanismAccording to the characters of the working device, it was simplified into a 2-DOF mechanism with two length variants. The change of main parameters according to the variation of the bucket handle was deviated through the reverse calculation of the motion trace formula. During the mining process, the continuous increase of the earth leads to the constantly changing of the center-of-mass coordination and the moment of inertia of the bucket. The problem was resolved by the transformation of the bucket coordination and the device coordination. 3.Driving force calculation of the working device and dynamic analysis of static forceBy determining the pushing force and lifting force at some extreme positions of the lifting and pushing mechanism which are the main devices of the working apparatus, thus a rough estimate of driving force was obtained. And the driving motor was chosen and checked accordingly. Since the excavator is of a mass volume, the inertia force and torque should not be neglected. By adding the inertia force and torque and applying dynamic analysis to the mechanism, a linear equation set of 12 unknown variants was obtained. The curve line of the pushing force and howling force was drafted by math software.4. ADAMS simulation of working device mechanismIn order to check the solutions of the dynamics and kinematics formula, as well as for the reference, a simulation of the working device was carried out using ADAMS-powerful multi-body system simulation software. The PRO/E 3-d model of the working device was imported to ADAMS after a proper simplification. The restriction and force load were applied to the model, and the driving force was defined by the Spline function, then the simulation results for the dynamics and kinematics of the working device were deducted. Analysis and explanation were given for the results.5. The calculation of the crawler traveling devicecrawler traveling device is the supporting and driving chassis of a mining excavator. The fundamental structure of the walking device was presented in this paper. And PH2300 excavator was taken as an illustrative example, and its pulling force and driving resistance were calculated. The achievements of this paper could serve as a reference for the design of the large mechanical mining machinery especially the choose of howling and pushing motors, and it is also provide a reference to the design of the crawler traveling device. |
