Study on the bearing characteristics of overrun hydraulic support under impact loading

In order to study the effects of stress change and adaptability of the overrun hydraulic stent under impact load, the rigid–flexible coupling numerical model of the stent is established using multi-body dynamics simulation software ADAMS. In the model, the stent is flexibilized using the HyperMesh module, and the column and jack are equivalently replaced with a spring damping system. By applying impact loads to different positions above the front roof beam of the stent, the dynamic response characteristics of the column and the articulation point are obtained at different positions with different strengths. The results show that when the impact load is applied to different positions of the front roof beam, the steady-state response force of the column shows an overall “M" distribution, and along the length direction of the roof beam, the steady-state response force of the column shows an upward trend, and the maximum steady-state response force of the column is 547 kN at point (1, 6); when the impact load is applied to both sides of the front roof beam, the response at the articulation point is greater, resulting in a higher maximum simple harmonic response at that articulation point. When the impact load acts on both sides of the front roof beam, the response of the articulation point is greater, with a maximum simple harmonic response coefficient of 0.75 and a maximum excitation response coefficient of 0.28; when the impact loads of different strengths act on the whole front roof beam, the force acting on the column and pin shaft at the articulation point will produce a large impact, reducing its adaptability. To address this, we can consider changing the top plate stress conditions using methods like high-pressure injection of water and control the gradual and slow release of the top plate stresses. The results of the study provide a reference for the structural strength design and reliability analysis of the hydraulic support, which is of practical significance and value for improving the safe mining of the coal mining face

Design of pedestrian monitoring and protection system of continuous shearer

In view of potential safety hazards of accidentally injuring pedestrians during operation process of conveyor at the back of continuous shearer, a pedestrian monitoring and protection system of continuous shearer based on infrared thermal imaging was designed. Firstly, long-wave infrared probe was used to monitor sensitive areas of the conveyor at the back of continuous shearer and real-timely collect infrared image information in the sensitive areas. Then, microprocessor was used to process the infrared image information, and pedestrians were detected; when pedestrians were detected entering the sensitive area, the pedestrian information would be rapidly judged by microprocessor within 1 s, meanwhile an early warning protection strategy would be triggered; when the pedestrians exited the sensitive area, the early warning protection mechanism would stop automatically; when the pedestrians passed over the sensitive area, at that time, an emergency stop control strategy would be triggered by microprocessor, so as to make the conveyor at the back of continuous shearer stop urgently to protect safety of crossing pedestrians. The site test results show that the system is stable and reliable with high recognition accuracy, and can effectively monitor pedestrians within the range of 1 to 2 meters on the front left area of the conveyor at the back of the continuous shearer, which effectively guaranteed life safety of pedestrians nearby the continuous shearer

Application prospect analysis of new technologies of mine-used belt conveyor

Introduction and application prospect of new technologies were discussed such as centralized control and unattended intelligent control of conveyor belt, anti-tearing of conveyor belt, new technology of energy saving and reduction, rapid installation and withdrawal technology. The realization of unattended monitoring was described from three aspects of vision function, hearing function and touch function. A new longitudinal tearing recognition device for mine conveyor belt was introduced, it uses camera video recognition technology to identify and judge damage of conveyor belt real timely. It is analyzed that application of new rubber conveyor belt with aramid as the skeleton material, the intelligent technology of video recognition, and low-resistance stainless steel roller can effectively save energy and reduce consumption. A non-foundation fixing method for rapid installation and withdrawal of belt conveyor was introduced. The application of the new technologies of mine-used belt conveyor will gradually realize the functions of high intelligence centralized automatic control, quick and efficient installation and withdrawal of belt conveyor, and lay a solid foundation for safe, high yield and high efficiency of coal mine

Design and application of manual pressurization device for initial support force of hydraulic support

In view of safety problems such as premature separation of roof, advance of cutting line and rib fall of coal wall caused by being lack of initial support force of hydraulic support, a manual pressurization device for initial support force of hydraulic support was designed. The pressurization device is in parallel with hydraulic check valve of original support lifting hydraulic system, improves the initial support force through manual operation of pressurization under the premise that normal lift is not affected. AMESim modeling and simulation of the pressurization control circuit before and after applying the manual pressurization device were carried out. The simulation results show that the manual pressurization effect of the device is obvious. The field test result of pressurized situation for initial support force of ZY8500/21/45D type support on a coal mine working face shows that the manual pressurization device can significantly improve initial support force of the support and meet the coal mining demand

Design of high cutting chock type hydraulic support

In view of problems of poor support effect, slow support speed, high support cost and great labor intensity of advance support with advanced hydraulic support, single hydraulic prop or timber in return airway of fully-mechanized high cutting coal mining face of a coal mine in Yulin mining area, a high cutting chock type hydraulic support was designed. Finite element analysis of the support was conducted under three kinds of operating conditions namely top beam eccentric load and pedestal torsion, top beam torsion and pedestal concentrated load, top beam concentrated load and pedestal eccentric load. The stress nephogram and deformation nephogram show that the whole support is stressed uniformly without apparent stress concentration phenomenon and large deformation. The field test result show that the support can effectively guarantee safety of working face roadway with small deformation of surrounding rock of roadway

Optimal design of balance jack control loop of hydraulic support

Principles and shortcomings of balance jack control of hydraulic support by use of compensation valve, high pressure internal overflow valve, floating two-way lock and automatic balance valve respectively were analyzed, and an optimal design scheme of the balance jack control loop of hydraulic support was proposed according to pressure characteristics of the balance jack cavity. Automatic fluid replacement and unloading of the balance jack cavity are realized by reasonably disposing components such as hydraulic pressure controlled reversing valve and low pressure unloading valve, so as to solve problem of safety valve frequently opening under non-emergency situation. The simulation and test results verify effectiveness of the optimal design scheme