Development trend of rock drilling equipment is to use hydraulic rock drills
Modern drilling rigs and advanced blasting techniques are the keys to shortening the drilling process time in the tunnelling cycle. Practice has proved that the performance of hydraulic rock drill is better than that of pneumatic rock drill, which not only saves energy significantly, but also improves the working environment. The simbah252 hydraulic mining drilling rig is mainly used for underground mine caving mining to drill vertical fan-shaped or annular blastholes, and can drill parallel blastholes with a spacing of 1.5m in the vertical direction. The drilling rig is equipped with an advanced hydraulic rock drill, which is most suitable for medium Deep hole connecting rod rock drilling, the hole depth can reach 30m.
1. Analysis of hydraulic system of mining drilling rig
The hydraulic system of the drilling rig can be divided into three parts according to its functions and functions, namely the positioning system of the drilling rig, the rock drilling system and the walking system. The functions, working principles and characteristics of these three parts are analyzed and explained in detail below.
The positioning system of the drilling rig mainly plays two roles of stabilizing the whole vehicle and fixing the drilling arm when the drilling rig is working. The actuator of the whole system consists of 1 motor and 11 oil cylinders. The motor can make the drill boom rotate 360°, of which 4 foot cylinders play the role of stabilizing the drill rig, 2 upper and lower pillar cylinders play the role of fixing the drill boom when the drill rig is drilling, and the other 5 cylinders make the drill boom stable Pitch, roll, and move up and down.
The positioning system of the drilling rig is relatively simple. The pressure oil pumped by the hydraulic pump passes through the high-pressure filter, the reversing valve 5 and the pressure reducing valve 6. After the pressure drops to 12mpa, it acts on each positioning actuator through the reversing valve group. The return oil of each actuator flows back to the oil tank through the reversing valve group.
The 11 oil cylinders in the positioning system have a blocking function. The pressure oil acts on one side of the oil cylinder through the hydraulic control one-way valve. The control oil opens the hydraulic control one-way valve, and the oil flows. After the oil cylinder action reaches the required position, the oil supply is stopped; Due to the function of the hydraulic control one-way valve, the oil in the cylinder does not flow due to external force, and has a self-locking function. When the upper and lower strut cylinders are extended, the pressure oil will be decompressed to 2mpa and 7mpa by the one-way pressure reducing valve and then act on the bottom of the piston to ensure the smooth operation of the piston and accurate positioning, so as not to cause poor positioning due to excessive pressure. The mechanical structure of the drilling rig can be calibrated and destroyed; when the piston rod is retracted, the return oil returns to the oil tank through the check valve and the reversing valve 7 to achieve rapid recovery. Since the actuator of the positioning system is basically a double-acting plunger cylinder, it is characterized by sensitive response, rapid and accurate action. In order to ensure the stability of the drilling rig when it is working or parking, each oil cylinder is equipped with a self-locking valve, and the inlet and outlet of the two pitching oil cylinders and the two small side swing oil cylinders are equipped with one-way throttle valves to ensure that the oil cylinders can run in both directions. It can be stable without pulsation, and the resistance of oil returning through the one-way valve is small.
The walking system, also known as the traction system, is composed of a hydraulic motor, a steering cylinder, a brake cylinder and a hydraulic valve. The walking, steering and braking of the vehicle are completed by the walking system. Since the pump station is driven by a motor, the walking distance cannot exceed the length of the connected cable, and the long-distance walking can only be driven by other motor vehicles. The pressure oil manual reversing valve 10 reaches the valve group 5 through the bypass type speed regulating valve 9 and the sequence valve 8. The reversing valve 7 sends the control oil to the reversing valve side of the valve group 5, and the pressure oil in the main oil pipe A circuit is formed to make the motor turn or the cylinder act to complete the walking or turning. The stop valve 3 and the stop valve 4 must be turned to the closed position when the pump station drives the walking, and the stop state is in place, and the steering cylinder and the hydraulic motor can move to complete the steering and walking tasks; when the trailer is towed, the stop valve 3 and the stop valve 4 are connected. , Steering cylinder and hydraulic motor and shut-off valve form a closed circuit, and the follow-up action is completed when the trailer is towed. During the rock drilling process, shut-off valve 3 and shut-off valve 4 should be connected to avoid misoperation and equipment failure.
The speed regulating valve 9 makes the running speed of the steering cylinder adjustable. The valve group 5 is composed of a hydraulic reversing valve and a one-way sequence valve. When the load pressure exceeds the set value of the sequence valve by 28mpa, the pressure oil is unloaded through the sequence valve to achieve the purpose of protecting the actuator.
The function of the differential pressure reducing valve 11 is to keep the control oil pressure at 3mpa. The one-way sequence valve 8 has two modes, external control and internal control, to ensure that the sequence valve can be turned on under any circumstances. The speed regulating valve 6 is installed on the control oil circuit at both ends of the reversing valve 7, so that the control oil flow is stable without fluctuation, and the reversing valve 7 is guaranteed to be stable without impact, so that the starting speed of the drilling rig is stable and there is no jumping.
The rock drilling system supports the rock drill of the drilling rig to complete the rotation, impact and propulsion actions to meet the needs of actual rock drilling conditions.
The pressure oil provided by the rotary pump 2 leads the oil flow to the rotary motor of the rock drill through the reversing valve 17 of the rotary circuit, and returns to the oil tank through the cooler and filter to form a circuit.
Shock pump 3 is used for shock, positioning, propulsion and traction circuits. The pump has pressure compensation performance and is pre-adjusted to 28mpa with safety valve 7 to protect the circuit. The oil from the impact pump 3 flows partly to the pressure reducing valve 20, partly to the impact reversing valve 15, and there is an outlet through the pressure reducing valve 20 to the propeller, the positioning device and the drill pipe seat.
The shock oil flows to the shock machine through the reversing valve 15. High shock pressures are obtained when the valve is moved to the r position. The shuttle valve 8 prevents oil from flowing back to the tank through the reversing valve 15; when the reversing valve 15 is moved to the 1 position, a low surge pressure is obtained as the oil passes through the restrictor 11. The pressure is indicated on the pressure gauge 9 . The return oil of the shock circuit is turned back to the tank through the cooler and filter to form a circuit.
In order to obtain different predetermined speeds when opening the hole, connecting rod and rock drilling, the system is equipped with a relief valve and a reversing valve 21, these relief valves control the pressure reducing valve 20 to obtain three thrust pressures.
Propulsion when opening the eyes: When opening the eyes, the propulsion speed and pressure must be limited. Through the reversing valve 21, the relief valve 23 controls the pressure reducing valve 20 to provide a propulsion pressure of 2 mpa, and the reversing valve 14 makes the oil flow through the speed regulating valve 12a, thereby The propeller is propelled at a low speed, and the reversing valve 10 is used to control the action direction of the propeller.
Propulsion during rock drilling: During rock drilling, the relief valve 24 controls the pressure reducing valve 20 to provide a propulsion pressure of 7 mpa through the reversing valve 21. At this time, the valve 14 does not act, so the oil passes through the flow control valve 12b, which is a Fully open, oil flows continuously to the thrusters, which receive the amount of oil required for the actual piercing speed. During rock drilling, such as drilling into a cavity, the speed regulating valve 5 can limit the speed by limiting the oil return from the propeller.
Propulsion when connecting, unloading and operating the drill pipe: the fast forward and backward advance of the drill pipe when connecting and unloading the rod is controlled by the reversing valve 16, and the reversing valve 21 makes the relief valve 25 control the pressure reducing valve 20 Provide a propulsion pressure of 14mpa, and the c of the air valve gives an air pressure signal to make the reversing valve 16 move to realize the forward and backward movement of the propulsion cylinder; when connecting and unloading the rod, the forward and backward propulsion speed and rotation speed and screw thread. suit the speed. Valve 14 does not work, valve 10 is in position f when the rod is connected, and is in position b when the rod is unloaded. The four one-way valves 4 act as rectifiers, and the flow speed regulating valve 12 adjusts the propulsion speed to match the thread of the drill pipe.
Anti-sticking device: It has the function of reducing the risk of sticking of the drill pipe and the drill bit when drilling rocks with cracks or cavities. When the drill bit or the drill pipe is stuck in the hole, the pressure of the rotary circuit increases. When the pressure exceeds the preset value of the pressure switch 7, the pressure switch will act, so that the reversing valve 10 is at the position b, and the push cylinder returns at this time. When the pressure of the propulsion circuit drops, the pressure switch 6 is actuated, and it gives an electric pulse to the shock reversing valve 15, and the valve 15 turns into a low pressure shock.
When the pressure of the rotating circuit drops below the set value of the pressure switch, the switch does not act, and the reversing valve 10 and the reversing valve 15 act in the opposite direction again, continue to advance and continue to turn into high-pressure shock.
A8v58dd2r101f1 biaxial piston variable pump 3 with pressure compensation, used for impact, propulsion, drill pipe seat, positioning, traction circuit. It is powered by a 55kw motor, the maximum displacement of the pump is 58cm3r-1, and the rated speed of the motor It is 1480rmin-1, the gear ratio of the pump is 1.24, the speed of the pump is 1830rmin-1, and the maximum flow rate is 106lmin-1. When the system pressure is lower than the pressure setting on valve 5, the positioning of the valve is controlled by the spring, the valve is closed, and the system pressure acting on the rod side of the regulating piston keeps the pump at maximum displacement. When the system pressure rises to When the pressure is set, valve 5 is opened, the system pressure is transmitted to the piston side of the regulating piston, and then the pump is re-regulated to reduce the displacement to the equilibrium position, that is, the oil flow at the pressure setting value of valve 5 matches the requirements of the system . The restrictor 4b between the valve 5 and the regulating piston 4a is used to prevent the fluctuation of the pressure change in the regulating system. The regulating piston is spring loaded and gives full displacement at start-up.
When the oil volume of this pump is used for rock drilling, the pressure reducing valve 8 acts through the reversing valve 9; Lower the pressure.
Pump 2 is used to manually adjust the flow and is used for the rotating circuit. Its flow can be adjusted manually, and the adjustment range is 0 ~ 106lmin-1.
When rock drilling, the working pressure of the rotating circuit is adapted to the pressure required to resist the rotating resistance, and depends on the rotational speed, the type of drilling tool used and the nature of the rock being drilled. The normal value is usually between 4 and 5 mpa. The safety valve of the rotating circuit is preset to 11.5mpa to protect the rotating circuit.
2. System failure phenomenon and its maintenance
The impactor of the hydraulic rock drill is a high-frequency movement impact mechanism with an impact frequency of 40-60hz. During the movement process, the flow changes in the system are violent unsteady flow, resulting in high-pressure impact and damage to components such as pump valves and hoses. larger. In addition, due to the failure of the seal of the rock drill, a small amount of mineral powder and water enter the oil, which will increase the wear of the rock drill, valve block and cylinder and other components, and the system will be polluted greatly, increasing the probability of system failure. Common fault phenomena and solutions as follows.
2.1. The system shock pressure drops
During the working process of the rock drilling rig, the impact pressure gradually decreases, resulting in the phenomenon of pressure drop. This is mainly due to the leakage of the impactor guide piston of the rock drill, the wear of various components of the system, the increase of the gap, the excess leakage itself, and the volumetric efficiency of the high-pressure pump. factors such as decline. Solution: In order to prolong the working period, an appropriate energy storage device can be installed in the shock system to supplement the leakage and absorb the high-pressure shock wave, so as to effectively protect the system and keep the shock pressure stable.
The rock drill is an impact mechanism with high frequency and violent motion. Its impact frequency is 40-60hz, and the high pressure shock wave formed generates several times the working pressure. Although the circuit has a safety valve, the rock drill accumulator absorbs part of the shock wave, but most of the pressure wave It acts directly on the pump. Generally speaking, the reversing time of the constant pressure valve is 50-60ms, but the response capacity of the pump is 3-5hz, so the variable of the pump lags far behind the effect of the shock wave of the pump.
In rock drilling conditions, the displacement of the pump is generally adjusted to the maximum angle, that is, the position where dead ends are likely to occur, so that although there is a high flow output, at this time the plunger hinged ball sleeve bears a large force, and the wear is increased. , the ball head breaks and cracks fall off, so that the surface of the plunger and the cylinder is scratched, and the volumetric efficiency decreases; the oil distribution plate has the most critical influence on the volumetric efficiency. If the components such as body and constant pressure valve are worn, it will bring great difficulties to the repair work. From the site, the damage degree of the a8v pump is 80% caused by this.
The gear speed-increasing mechanism of a8v pump, if the lubrication of the gear is not in place or the wear clearance increases, or the bearing clearance increases, it will cause vibration, the noise of the pump is large, and the output flow pulse is intensified, which will have a certain impact on the pump and system components. The solution is to prevent contamination, regrind the valve plate and replace the pump with a new one.
The hydraulic rock drill is the most important executive component of the trolley system. After many experiments and analysis, internal leakage is the main factor affecting its normal operation. In actual use, the impact caused by internal leakage is often ignored. When the test pressure is 11mpa, if the internal leakage of the impact part exceeds 5lmin-1, the impact pressure and impact frequency will decrease. The damping piston should be repaired at this time, and the corresponding inspection should be carried out to reduce the internal leakage of the impact part to 1 ~ 3lmin-1. When the test pressure is 4mpa, the internal leakage of the rotary motor should be controlled within 8lmin-1. However, due to the large flow reserve of the rotary pump, adjusting the flow of the rotary pump can compensate for the influence of leakage in this respect. In actual use, If the pressure of the rotary system exceeds 10mpa, it means that the gear meshing is too tight, the drill rod is stuck in the drilling rig, and the anti-jamming drill valve does not work. Depending on the type, the overhaul period of the cop1038hd type is about the operation time of drilling a 6000m rock hole.
Through the test of the four pressure reducing valves in the single-arm system of the trolley, it is found that the average leakage sum is 13lmin-1, and the reasonable total leakage should be less than 4lmin-1. The online test method of this type of pressure regulating valve is to adjust the t The mouth is connected, and the leakage amount is measured with a measuring cup. When the pressure of the impact rotary combined reversing valve is 15mpa, the average total leakage is 3.2lmin-1. The leakage path of the valve is the wear of the reversing valve core, the leakage of the safety valve, and the reverse leakage of the check valve. When the low-flushing valve group is at 25mpa, the average leakage is 0.025lmin-1, and the opening pressure of the relief valve of the valve group of 30 is less than 15mpa, and some even have been opened at 2.5mpa. The on-line test method for the low-stroke valve group can disconnect the pipeline of the hydraulic pump leading to the low-stroke group. If the system pressure rises, the valve group has internal leakage. Therefore, it can be seen that the impact damage of the safety valve spool is relatively serious. The average leakage sum of other hydraulic valve arm positioning reversing valves, apb valves, anti-jamming reversing valves, etc. should not exceed 1lmin-1. From the above test results, it can be seen that the average leakage sum of hydraulic valves in the single-arm system is about 20lmin-1. , In addition, there are 30 check valves in reverse conduction, and the hydraulic lock failure is 20, which will affect the working efficiency of the working system. The repair of the hydraulic valve mainly adopts the method of increasing the valve core, and then matching it with the valve body. If it is a poppet valve spool, it is best to reprocess the spool and grind it with the valve seat.
The number of hydraulic cylinders in the trolley system is quite large. From the leakage detection results of the trolley cylinders, it can be seen that the average leakage of the outrigger cylinders, telescopic cylinders, roof cylinders, thruster extension cylinders and other cylinders is very small. The average leakage is 10lmin-1, the average leakage of the gondola cylinder is 12lmin-1, and the average leakage of the propulsion cylinder is 8lmin-1. During the test, it was found that the leakage of the cylinder is mainly concentrated in the regular working section of the cylinder stroke; The leakage of all the cylinders detected is calculated as an average, then the sum of the average leakage of all the cylinders of the single arm is 18lmin-1. There are two main ways to solve the leakage of the oil cylinder. The first method is to replace the oil seal of the oil cylinder piston, but it has little effect on the oil cylinder that leaks in the frequent working section, because the inner diameter of the cylinder in the frequent working section of the oil cylinder is worn. At this time, the method of wear-resistant repair glue is used to restore the inner diameter of the cylinder to the original size. The effect of long-term use is very ideal, especially the slender cylinder with the inner diameter of the cylinder is more superior.
3 The necessity of establishing a professional maintenance team Modern underground mining equipment has tended to be trackless, hydraulic, continuous, diversified in power sources, comprehensive mechanization of auxiliary operations and partial automation of production equipment. After entering the 1990s, electronic computers have been gradually applied to rock drilling rigs, robots and optical fiber communication technology have also begun to be applied in some foreign mines, electronic sensors, smart chips, etc. The use of hydraulic servo mechanism, long-distance tracking and local automation equipment is increasing day by day, and the current rock drill can also realize electronic monitoring and remote control operations. With the improvement of the technical level, the complexity of the system has also increased, and now domestic mining enterprises generally have the problems of poor personnel quality and low management level, so that good equipment cannot play the maximum effect. Therefore, a sound technical service system and professional It is very necessary for the maintenance team to carry out necessary technical training for employees. It is of great significance to reduce the occurrence of failures, improve the service life of the machine and increase the output.
Starting from the actual situation of on-site use and referring to a large number of materials, the working principle of the hydraulic system of the simbah252 trolley is systematically and detailedly analyzed.
It analyzes and summarizes the common faults of the hydraulic system of the simbah252 rock drilling rig, as well as the reasons for the faults and the treatment methods.
The hydraulic system, working principle and structural characteristics of the hydraulic rock drilling rig are discussed in detail and comprehensively, which are worthy of reference, promotion and application in similar mines.
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