| Coal sampling machine is used to collect and produce representative coal sample.At present,the coal sampling manipulator that domestic used commonly is difficult to meet the sampling quality and sampling efficiency requirements.In this paper a working device of articulated coal sampling machine is proposed,and its dynamic characteristics are studied.The sampling machine can be sampled at the same time as the train travels,greatly reducing the sampling time and achieving full cross sectional sampling requirements.However,due to its poor working environment in the actual sampling process,the load of working device is large and fluctuated intensely.The force situation is difficult to calculate.And the dynamic and random characteristic of the load is the main reason of structural failure,which leads to the reliability of the sampling progress is difficult to guarantee.Therefore,the full use of the advantages of various software combined with the characteristics of the sampling machine,to analysis the force of working device at any time and strength check is particularly important.Firstly,the three-dimensional model of articulated coal sampling machine working device was established by SolidWorks.A trajectory of the end point of a sampling head is designed according to the actual sampling requirement.The kinematics models of the working device are established by analytic geometry method.The curve of the displacement of each joint was calculated by MATLAB programming.And according to the kinematics positive solution equation,considering the range of the hydraulic cylinder,the rotation angle range of the rotary motor and the interference problem between the hydraulic cylinder and the arm,the working space of the coal sampling machine is determined by numerical solution.Secondly,the three-dimensional model of sampling machine that produced by Solid Works is imported into the ADAMS software.The displacement of each joint that obtained by kinematics simulation and insertion resistance of sampling head are used to simulate the double-action sampling process.The stress curve at each hinge pin point along with time of working device during sampling was obtained through simulation,which solves the problem that the force is complicated and difficult to calculate in the sampling process.And provides data support for the following finite element analysis of the coal sampling machine's working device.Finally,the working device is imported into the finite element analysis software ANSYS Workbench for structural dynamics analysis.The modal analysis of the working device is carried out to determine its natural frequency and vibration mode.The harmonic response curve of the working device is obtained by the harmonic response analysis.Through the transient structural analysis of the working device of the sampling machine,the dynamic stress characteristics of the working device in the normal sampling process are obtained.And the analysis is closed to the actual work situation.The result shows that the maximum stress of each arm appears at different moments,and the structure of the sampling machine is reasonable and the strength meets the requirements.This study provides a theoretical basis for the further optimization of the structure of the sampling machine,and it has some guiding significance for analysing the transient strength of the mechanism of complex forces throughout the motion. |
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