Posture and Dynamics Analysis of Hydraulic Support with Joint Clearance under Impact Load

Abstract

A hydraulic support is one of the key pieces of equipment in a fully mechanized coal-mining face. The shaft is seriously worn due to repeated support shifting in coal-mining operations, and the hydraulic support bears a large amount of impact load in the support process, leading to a threat to its dynamic stability. In order to study the impact load on the posture and dynamics of a hydraulic support, and considering the joint clearance of the hydraulic-support hinge point, based on the dynamics software Adams, the equivalent variable-stiffness damping system is used to replace the column, and the impact analysis model of the hydraulic support with joint clearance is established. The roof pressure is vertically applied to the load balance area of the top beam by static load, and the impact load is vertically applied to the top beam downward. Based on the above model, considering the different distributions of joint clearance, research about the influence of joint clearance on the posture and dynamic characteristics of the hydraulic support is carried out. The results show that when there is joint clearance on both sides of the hydraulic support, when the top beam bears the impact load, the X-axis PMR (position movement ratio) at different positions of the top beam is more than 80%, and the forward-tilt posture is obvious. When the hydraulic support has only unilateral clearance, the front end of the top beam bears the impact load, and the front end of the top beam moves laterally, while the rear end of the top beam mainly moves longitudinally. When the end of the top beam bears the impact load, the vertical PMR of the top beam is less than 1%. When the impact load acts on the side with joint clearance, the top beam has a certain degree of lateral offset, and the offset directions on both sides of the top beam are inconsistent. At this time, the top beam presents a torsional-bearing posture. When the front end of the top beam is loaded, the mechanical curve of each hinge point is higher than the rear-end load. For the hinge point on the side without clearance, the maximum load-fluctuation coefficient reaches 1.04, while for the hinge point on the side with clearance, the minimum load is 0 kN, which will mean some hinge points cannot to play a supporting role. The analysis results will be helpful to research hydraulic supports considering joint clearance.