| This paper aims to study a kind of color changeable sensor for in-situ monitoring axial force of rock bolts.As an effective method for supporting coal roadway,rock bolting technology has important safety and economic benefits for the daily production of coal mines.Due to the complexity and concealment of the anchorage project,the detection of the quality of rock bolting becomes difficult and complex.In order to avoid accidents such as roof fall,reasonably design of support parameters and improve safety while saving support costs,the axial force of rock bolts must be monitored online.Therefore,the design and research of sensors for monitoring axial force of rock bolts have important scientific and practical value.According to the shortcomings of traditional monitoring devices,a new type of sensor is proposed to indicate the stress of the bolt through different colors.First of all,the design of the scheme of the sensor to change color is completed,the axial force of rock bolts is converted into the hydraulic pressure,and the opening or closing of the valves and pipes are controlled by the pressure,and the color is changed through the combination of the colored liquids in the color chamber to indicate the stress of rock bolts.The structural design of the sensor was completed through the design of the pressure reducing mechanism and the distribution ring,and oil was selected to change color.The parametric design of decompression mechanism,pressure reducing valve,check valve,pipe,and color chamber inflation pressure was completed,and the calculation of the strength of the decompression component,the static characteristics of the valve group,and the pressure loss of the pipe were completed to ensure the normal operation of the sensor.The system model was established in AMESim,and the design parameters were imported.Through the analysis of static and dynamic characteristics,the accuracy,repeatability and impact resistance of the sensor were simulated.In addition,the experiment of the color-changed scheme shows that the sensor can change the white,green,yellow,and red colors as the force of bolts changes.Finally,the performance of the sensor was analyzed.The influence of oil viscosity under temperature and pressure changes on the dynamic characteristics of the sensor was completed to choose the oil,it shows that the L-AN32 can ensure the sensor work normally in 20°C difference in temperature.The simulation analysis of the effect of pipe diameter and roughness was completed,and the pipe parameters were determined as the pipe diameter of 1mm and the roughness of 25μm.The maximum allowable leakage of the system is 0.0228 L/min by setting the equivalent orifice parameters for simulation and analysis,The manufacturing technical analysis of the sensor structure was completed,and the geometrical tolerance and clearance of the valve were determined to be 0.007~0.015 mm.The structure of valve is optimized and improved to increase the pressure equalization groove and chamfer slope,so as to reduce the influence of the hydraulic clamping force and the steady state hydraulic force on the dynamic characteristics of the sensor.According to the structure of the sensor,requirements for processing,assembly and oil particle size are required to ensure the normal operation of the sensor.This paper proposes a new type of sensor that monitors the force of the bolts using color change.Firstly,the design of the system and structure are completed.The parametric design of the specific bolt is completed,and the simulation of static and dynamic characteristics was completed in AMESim.The effects of oil viscosity,temperature,pipe diameter and roughness,and leakage on the sensor were analyzed,and the process analysis was completed.The related parameters and improvements of sensor were determined.The results show that the sensor has strong environmental adaptability,and the monitoring system is feasible and effective.The expected monitoring effect of axial force of bolt is achieved. |
