Dynamic Characteristic Analysis And Performance Prediction Of Cutting Process For Boom-type Roadheader

Efficient mechanized tunneling is an essential way for mining industry to achieve highproductivity and efficiency. It is also the trend of the roadway excavation technology. As majorroadway excavation equipment, boom-typed roadheaders (BTR) are being developed towards theintegration of high-power, large weight and automation. However, a problem associated with thistrend is the machine dynamic characteristics will become more prominent and thus has asignificant effect on the cutting performance of roadheader. Under different operating conditions,the problem of vibration is mainly caused by the cutting head of BTR. Therefore, it is importantto study the dynamics of its cutting process and to predict the performance which is based on themachine dynamic characteristics. The current research and its shortage are analysised on thebasis of the research achievement abroad and home. This paper presents a systematical way ofanalyzing the excavation process of BTR using a combined method of theoretical analysis,numerical simulation, field measurement and experimental studies which mainly include thefollowing contents and conclusions:Firstly, the breaking mechanism of BTR’s picks was analyzed in order to set up the cuttingtheory suitable for BTR and to determine a formula from Russion scholar to calculate the cuttingforces during its working process. Based on the established theory and the formula, a no-gapvibration model and a nonlinear gap vibration model were constructed. The nonlinear gapvibration model was then simulated using software package Matlab. The selection range of thegap value between the pick and the holder of BTR was decided according to the dynamicresponse of the model. The simulation results were validated with experiments and this can beused as a theoretical basis for determining the gap between the pick and the holder of BTR.Secondly, taking into account the randomness of the interaction force between coal androck under different operating conditions of BTR, nonlinearity of the gap between the pick andthe holder and the nonlinear factors of the planetary gear drive, the non-linear dynamic model oftorsional vibration was established. The model takes into consideration of the main affectingfactors in BTR and provides a theoretical basis for the dynamic analysis of its cutting processand performance prediction. Results show that the numerical simulation agrees well with thedata measured from experiment.Thirdly, the coupling effect between the mechanical structure parts and the hydraulicsystem of BTR were considered when calculating the required driving forces of the lift cylinders and swing cylinders in the process of swinging cutting using equations derived from solid statics.The results were then adopted to analyze the rotational vibration of the rotary cylinder in theprocess of lifting and turning during swing cutting. Accordingly, a system coupling dynamicmodel was established for BTR during its swing cutting process.Fourthly, a nonlinear model focusing on the torsional vibration of BTR was established andanalyzed. In addition, the effect of random coal rock force, different operating parametersmatching and other factors on the dynamic response of BTR’s cutting head was also studied anddetermined. Numerical methods were used to solve the kinetic equations under differentconditions and the dynamic response of the cutting head was derived through simulation. Thecomparison of the simulation results and the data collected in experiment implies that thesimulation model agrees well with real situation. Numerical simulation was carried out in themachinery-hydraulic coupling model of BTR during the swing cutting process. The results werethen used to optimize the swing cutting parameters.Fifthly, the study of the nonlinear kinetic model of BTR has resulted to the application ofsimulation results to the performance prediction of BTR. Based on these results, the prediction ofthe productivity, instantaneous cutting rate and cutter consumption has been realized. Bycomparing the results with the actual data, they have reached a high degree of agreement.Finally, different cutting speed and the cutting rules under different gap value between thepicks and its holder of BTR were obtained throughout experiments using a pick cutting testmachine. It was also compared with the simulation results from the dynamic model and this hasprovided an accurate and efficient way to determine the cutting force of BTR.