单颗粒煤岩冲击放顶煤液压支架尾梁动态响应分析
Dynamic response of single coal-rock impacting tail beam of top coal caving hydraulic support
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摘要: 综合机械化放顶煤开采过程中煤岩垮落产生的冲击载荷会导致放顶煤液压支架的运动状 态发生变化,严重时会导致综放设备的冲击破坏。 为研究放顶煤液压支架尾梁受到煤岩冲击后的 动态响应及受力情况,利用机械系统动力学分析软件 Adams 建立放煤机构的刚柔耦合模型,通过 固液弹簧耦合理论计算出尾梁平衡千斤顶的刚度并用弹簧阻尼系统进行等效替换。 采用“煤岩直 冲”的方式对尾梁进行加载,并引入 Hertz 接触理论确定接触参数。 基于此模型,模拟煤岩颗粒冲 击承载区不同位置以及在不同放煤角条件下冲击尾梁的动态过程,最后通过与刚体冲击方式下的 仿真结果对比,验证了所用方法的可靠性。 结果表明,煤岩冲击承载区不同位置时,尾梁的动态响 应量及碰撞接触力有差异,冲击位置位于尾梁-弹簧连接处附近区域时,碰撞接触力较小,而尾梁 的最大速度、加速度、振幅较大,在所有动态响应量中,最大振幅的变化规律最明显,随着冲击点位 置远离尾梁-掩护梁铰接处附近区域,最大振幅稳定上升;当放煤角逐步增大时,尾梁的动态响应 量及接触力均减小,尾梁的振动特性变弱,当放煤角较小时,煤岩冲击尾梁后会产生数值巨大的碰 撞接触力。 可选取尾梁的振幅响应作为反馈量对尾梁进行动态监测,同时应针对碰撞接触力较大 的情况在放煤机构的设计制造中对其进行强度校核及结构优化,避免尾梁及其连接处冲击破坏情 况的出现。Abstract: The impact load caused by coal-rock caving in the process of comprehensive mechanized top coal caving mining will lead to the change of movement state of hydraulic support for top coal caving,if the impact load is serious, it will cause the impact damage of fully mechanized caving equipment. In order to study the dynamic responses and stress condition of the tail beam of the top coal caving hydraulic support after the impact of coal-rock,this paper used mechanical system dynamics analysis software Adams to establish the rigid-flexible coupling model of caving mecha-nism and calculate the stiffness of tail beam jack by solid-liquid spring coupling theory,then replaced the jack with a spring-damping system equivalently. This paper used the method of “coal-rock impacts the tail beam directly” to add load onto tail beam,and the contact parameter was determined by Hertz contact theory. Based on the rigid-flexible cou-pling model,the dynamic process of coal-rock impacting the tail beam at different positions and different coal caving angles was simulated. Finally,the reliability of the method was verified by comparing with the simulation results ob-tained by the way of rigid body impact. The results showed that the collision contact force and the dynamic response of tail beam were different when coal-rock impacts the different positions of bearing zone,if the impact location is near the tail beam-spring connection,the contact force is smaller,while the maximum velocity,acceleration and amplitude of the tail beam are larger. Among all the dynamic responses,the variation of maximum amplitude was the most obvious, it increased steadily as the position of impact point was far away from the area near the hinge of the tail beam and the shield beam. When the caving angle increased gradually,the dynamic responses of the tail beam and contact force de-creased,and the vibration characteristics of the tail beam became weak. If the caving angle is small,the impact of coal-rock will produce a huge numerical impact contact force. The amplitude response of the tail beam can be selected as the feedback quantity for dynamic monitoring of the tail beam. At the same time,to avoid the occurrence of impact damage of the tail beam and its connections,the strength check and structure optimization of the caving mechanism should be carried out during the design and manufacture of the caving mechanism in the case of a large collision con-tact force.