In order to obtain the determining method of the installing angle and decrease the performance indices (cutting force and wearing rate) of the pick, the relationships among the installing angles (impact angle, inclination angle and the skew angle) were studied, and the static model of installing angles of the pick was built. The relationships among the impact angle, the tip angle of pick and the kinematics parameters of the pick were built, too. Moreover, the mechanic models of the maximum clearance angle and the wearing angle of the pick were set up. To research the relationships of the installing angles and the change law of the wearing angle along with the kinematics parameters, the simulation was done. In order to verify the correctness of the models, the cutting experiments were done by employing two picks with different pick tip angles. The results indicate that, the cutting force is the smallest when the direction of the resultant force of pick follows its axis, and the relationship derived among the installing angles should be satisfied. In addition, to decrease the cutting force and the wearing of the pick, the tip angle of pick should not be larger than the half of the difference between the minimum wearing angle and the impact angle of the pick, and the clearance angle must not be less than zero.
Three drums with different helical angles(15°,20°,and 25°) were developed to investigate improved loading performance of the shearer drum.Nine trials were performed at different drum rotation speeds(80,100,and 120 r/min) and different haulage speeds(1.5,2.0,and 2.5 m/min) in an orthogonal test design.Loaded coal quantity and cutting power of the drum were the responses measured under the different conditions.The effect of the parameters was determined by means of the extreme difference method.The significance of the effects was determined by analysis of variance.The results indicate that the effect from changes in the helical vane on loading performance of the drum is the largest in magnitude.The haulage speed has the least affect on loading performance.The helical angle has the least affect on cutting power of the drum.Haulage speed has the largest affect on the cutting power of the drum.
To research the loading characteristic of rocks with different structures cut by helical cutting mechanism (HCM),three different structures of rock (hard-soft-hard rock,soft-hard rock and soft-hard-soft rock) were built.And each type model was further divided into three types when the experiments were carried out.To reduce the errors of cutting load caused by manually configured rock in each test,the cutting load of soft rock was taken as a benchmark,and the differences of the cutting load of the different structures of rocks and the soft rock were used to reflect the cutting load change rules of the HCM.The results indicate that,the cutting load of only the HCM top cutting hard rock is larger than that of only the HCM bottom cutting hard rock for dextral HCM,and the cutting load fluctuation is larger,too.However,when the top and the bottom of the HCM cutting hard rock simultaneously,its cutting load is the largest,but the cutting load fluctuation is the least.And the HCM cutting load increment is increased linearly with the increase of rock compressive strength.The HCM cutting load increment is increased exponentially with the increase of hard rock cutting thickness.
The work presented in this paper focuses on improving coal loading performance of shear drum.Employing the similarity theory,we carried out a dimensional analysis of the correlation parameters which influence coal loading performance of shear drum.On the basis of similarity criterion,proportional relationship between the model and the prototype was taken on the condition of taking 1/3 as the similarity coefficient.Besides taking 1600 mm drum as the prototype,four helical angle models of shearer drums(15°,18°,21°,24°) were developed.Simultaneously,based on an established cutting test-bed,coal loading performance tests for the four drums were carried out at the same drum rotational and haulage speeds.After analyzing the data of coal-loading performance and torque,we concluded that:both the coal loading performance and torque vary along the track of the parabola with the opening side facing downwards;the best coal loading performance arises when the helical angle is at 19.3°,while the biggest torque arises at 22.1°;and the coal loading performance had nonlinear relationship with the torque.
