| There are a large number of end-coal coals in many open-air coal production bases in China,and the extraction of end-coal coals is of great significance for promoting the recovery and utilization of coal resources.However,the current open-end coal mining protection device is mainly constructed from steel plates.The protective device constructed in this way has poor impact resistance and can't provide effective cushioning against rockfall impacts;at the same time,the simple-built protection device can't move independently and requires a lot of manpower to demolish and rebuild,reducing the efficiency of end-coal mining and recovery.Therefore,the protective device not only needs to have good impact resistance to ensure the safety of coal mining equipment and workers;but also needs to have the performance of autonomous movement to save manpower and improve the recovery efficiency of end coal mining.Aiming at the shortcomings of the current coal mining protection device,this paper designed and researched a new type of caterpillar walking roof protective roof.The protective roof includes mechanical arch roof,anti-impact roof,support and self-propelled slewing device.Using Solid Works software,a three-dimensional model of each part of the protective roof was created,and a bottom-up method was used to assemble and design the protective roof,and a complete virtual prototype model of the crawler walking tunnel entrance was constructed.According to the movement of the caterpillar walking roof protection roof,the hydraulic drive system of the whole machine was designed,and the parameters of the system flow rate,hydraulic pump displacement,piston diameter,rod diameter and stroke of various oil cylinders were determined.Based on the working principle of the shunting and collecting valve,the HCD library was used to build its model in the software AMESim,and the hydraulic synchronization circuit of the protective ceiling telescopic height adjustment was established.The synchronization performance of the height adjustment telescopic cylinder under partial load conditions was simulated,and the displacement curve of the oil cylinder and the flow curve of the oil cylinder inlet and outlet under the condition of off load were obtained.Secondly,according to Hertz's collision contact theory and energy dissipation principle,a rigid flexible coupling model of rockfall track protection roof was established in ADAMS software,and the impact resistance of the protection roof was studied.At the same time,combined with the hydraulic system of the protection roof,the mechanical hydraulic joint simulation model was established to explore the impact law of different quality rocks on the protection roof at different heights.The results show that the stress of rock impact protective roof is mainly concentrated in the hinge position between protective roof and oil cylinder and the hinge position between protective roof.The stress of protective roof increases with the increase of rockfall quality and impact height;the expansion oil cylinder of protective roof can effectively release the energy brought by rock impact protective roof,and enhance the impact resistance of protective roof.The maximum energy that the plate can bear is 1200 J.Finally,the pavement adaptability of the crawler walking system was studied,and the multi-body dynamics simulation model of the track-protection roof was established by using Recur Dyn software,and the dynamic driving of the machine on the coal rock road horizontal and vertical driving and in-situ steering conditions was analyzed.The results show that the torque value of each track drive wheel is stable when the machine is running on a flat road in the vertical and horizontal directions,and the average value is about 2000 Nm.When the machine is running on the road surface in the vertical and horizontal directions,the torque of each track drive wheel will be reasonable.The range changes sharply within the range,and then tends to be stable.When the machine is running on vertical and horizontal climbing roads,the torque value of the crawler drive wheels at the rear of the machine is greater than the front of the machine due to the track installation position and the weight of the machine.For the simulation of in-situ steering conditions of the whole machine,the torque of each swing cylinder is stabilized at about 2000 Nm.This paper designs and develops the protective ceiling of crawler tunnel portal,and analyzes the impact resistance,energy dissipation and dynamic characteristics of the whole crawler tunnel portal.It verifies the reliability of the new protective ceiling of crawler tunnel portal,which is of great significance to improve the mining recovery of end wall coal and protect the safety of staff and equipment. |
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