| The excavation work of coal mine tunnels usually adopts bolt support,Major safety accidents occur from time to time in the roadway due to the failure of the support caused by the soft rock interlayer on the roof,and the collapse of the roof.In order to prevent roof fall accidents caused by soft rock interlayers,this topic proposes the automatic drilling and detection of mine tunnels to identify soft rock interbeds which use pneumatic bolters,sensors and controllers to detect the drilling parameters of the system,the torque and speed of the pneumatic motor,and the pressure and speed of the outrigger cylinder to detect the strength of the rock on the roof of the roadway.The main research results are as follow:(1)In this thesis,the unconfined compressive strength(UCS)of each rock layer of roadway roof is identified by detecting the motor speed and torque,the pressure of the outrigger cylinder and the drilling speed during the drilling process of the pneumatic bolter.(2)Based on the relevant theoretical knowledge of contact mechanics,the contact pressure between a single PDC and rock is deduced in detail on the basis of force analysis in the cutting process of rock,and the relationship model between the depth of drill into rock and the acting load is further established.The contact between PDC bit and rock with different geometrical structure is analyzed effectively and the related physical model is established,and then the factors and laws that affect the contact pressure are deeply discussed.(3)The shear strength of rock is far weaker than its compressive strength,which is about 1/8-1/12 of the compressive strength.According to this,the rock breaking effect will be better and better with the increase of the sharpness of the composite diamond sheet and the depth of rock pressed.Under the same bit weight condition,the sharper the PDC composite diamond is,the deeper the rock is pressed,and the better the rock breaking effect is.Therefore,the elliptical tip and triangular tip PDC bit with arc is proposed,which not only has good rock breaking effect,but also has wear resistance and impact resistance.(4)Combined with the calculation formula of contact pressure theory,based on the analysis of rock crushing conditions in press cutting,the rock crushing conditions are explored from the perspective of mechanical properties of rock compression,and the numerical analysis of rock breaking process is carried out.In the process of rock drilling with PDC bit,the factors such as WOB,ROP,rotational speed and torque are analyzed,and the data results of relevant parameters are analyzed.It is verified that the system can identify all kinds of rock hardness.(5)In the process of drilling,when both ends of the drill pipe are compressed,the drill pipe will lose stability and produce buckling deformation.The drill pipe will contact the hole wall of the drilled hole,resulting in friction,heat generation and wear.The instability of the drill pipe is studied,and the mathematical model of the shape of the drill pipe deflection curve is obtained.A kind of anti-wear device is designed,which can greatly reduce the friction between the buckling drill pipe and the anchor hole.(6)The mathematical model of the drilling power output of the drilling rig is deduced,and the drilling speed of the drilling rig can be optimized by using this model.Since the output power curve of the pneumatic motor is a parabola,the peak of the parabola is the maximum value of its output power.Therefore,as long as the maximum value of the parabola is found,the drilling speed of drilling can reach the maximum value,thereby being optimized.However,because the unconfined compressive strength of different rocks is different,the maximum power output by the air motor is also different.(7)In order to reduce the labor intensity of workers,increase the comfort of workers,the design of the anchoring machine carrying fixed vehicle,the vehicle can carry the anchoring machine,at the same time can be fixed in the working face of the anchoring machine,automatic,unmanned operation.According to the nonlinear characteristics of pneumatic bolt drilling machine,the method of controlling the pressure of leg by fuzzy PID bolt machine and controlling the drilling speed of motor by adaptive neural network is put forward.The system can control the pressure of the leg and the speed of the motor in a closed loop,and output the pressure of the leg and the speed of the motor according to the given signal,so that the drilling of the bolt drill is intelligent.(8)A testing system of automatic drilling lithology identification for roof strata is developed.It is found that the uniaxial compressive strength of the roof strata can be estimated more accurately by using the drilling parameters of the pneumatic anchor drill.The study found that the pneumatic motor output maximum power with different unconfined compressive strength of rock is associated with leg pressure,The outrigger pressure of the pneumatic bolt fixing device does not match the output power of the air motor,and the air motor cannot reach the maximum power point is due to insufficient thrust of the air outrigger,and the output power of the air motor cannot reach the maximum value.The outrigger pressure ratio when drilling hard rock.The outrigger pressure is more insufficient when drilling soft rock.In order to increase the output power of the air motor,and then increase the drilling speed,the system is designed with a booster valve.Through testing the drilling speed,it is found that the power of the air motor has a linear relationship with the drilling speed,which proves that increasing the motor power can increase the drilling speed. |
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