Design and adaptability study of miniature four-leg top coal caving hydraulic support

The miniature hydraulic support and its measurement and control system play a vital role in the physical test. In order to better integrate the engineering practice and ensure the scientificity, accuracy and authenticity of the test results, the SOLIDWORKS software is used to carry out three-dimensional modeling, motion simulation and strength test of the miniature support. The components required for the hydraulic system are non-standardly designed and modified. Based on the RC model concept, a compete hydraulic, and measurement and control system is configured, and the mechanical properties of the support are tested accordingly. The results show that the miniature support can meet the requirements of controllable multivariable in the test by controlling the pressure of the pump station and cooperating with the hydraulic valve under the premise of similar structure and bearing characteristics. Taking the MNZF0.2/0.55/0.84 miniature hydraulic support and measurement and control system design as an example, this paper provides the specific steps of support structure design, the reasonable conversion formula of hydraulic system, and clarifies the design ideas and precautions of support. Support strength, stiffness stability, pump station pressure can reach more than 3 MPa, much higher than the test requirements. The motion curve of the front beam of the support conforms to the characteristics of the double lemniscate, and the range of motion trajectory is only about 0.46 mm, which is less than the theoretical optimal value. The support can well meet its bearing characteristics and motion requirements in the stages of initial support, resistance increasing, constant resistance and pressure relief. After testing, the working resistance of the support is about 168 N, the corresponding support strength is 0.54 MPa, and the system pressure still has a large margin. The side support jack adopts the same hydraulic system as the support legs, which can protect the coal wall. The support system composed of support jack and top beam can better reflect the coupling characteristics of the surrounding rock of the support. The research results can provide help for univariate or multivariate analysis of physical tests related to the coupling between support and surrounding rock. The test data of coupling with surrounding rock has important reference value for field application.