Design of the hydraulic system of the latest roadh

2022-08-18
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Design of hydraulic system of new roadheader

1 overview

with the rapid development of national economy, power and energy are becoming increasingly tense. Since most of the power industry in China is thermal power generation, the demand for coal is increasing. In order to strengthen safety production, the state has closed small coal mines, supported large coal mines, and increased modern equipment for coal mining, which has driven the great development of coal mining machinery in terms of policy

2 use, composition and working condition of roadheader

roadheader is a comprehensive tunneling equipment that integrates cutting, shipping and walking. It is used to cut the underground roadway with arbitrary section shape. While driving the coal roadway, use the bolt machine to drive the side and top of the coal roadway for support. Then the shearer can enter the roadway and ride on the scraper conveyor for coal mining and transportation

the roadheader is composed of five parts: cutting part, shipping part, traveling part, body part and rear support part, as well as three major systems: hydraulic, electrical and waterway. Except for the cutting part, body part and electrical system, other parts are driven by the hydraulic system

when working, the outrigger cylinder of the rear support part supports the ground, the explosion-proof motor of the cutting part drives the cutting head to rotate, and the hydraulic cylinder drives the cutting arm to rotate and lift, breaking the coal (rock). The coal falls on the shovel plate of the shipping department, and the shovel plate can be lifted and lowered. Two star wheels are installed on the shovel plate, and the star wheel rotates to send the coal falling on the shovel plate to the scraper of the first transportation and transport the coal out. The roadheader can run by itself, and the inner and outer water spray systems are installed at the head for dust suppression

3 characteristics of the hydraulic system of the old roadheader

the old roadheader is designed with reference to Japanese technology and developed in the 1950s and 1960s. After continuous improvement, the EBZ150 is taken as an example to illustrate the advantages and disadvantages of the system:

(1) the system adopts the form of multiple pumps and multiple groups of valves. Five gear pumps, many models, need to add transfer case, real 3 The cost of specifying the experimental method of impact testing machine is not low. When working in hard rock or semi coal rock, the roadheader needs to bear large external force impact. Because the working pressure of the large displacement gear pump is not high, the hydraulic impact capacity is poor, and it also works continuously, the service life is low. Because the underground place is small, the environment is poor, the maintenance is extremely inconvenient, and it is easy to cause secondary pollution

(2) domestic three position six way valve is adopted, which has large internal leakage and is easy to leak oil between pieces and at the control lever. Because the 25m straight-line deviation is relatively large, it is troublesome to select the motor power for walking

(3) there are many valves, which are scattered, and the pipelines are messy and occupy space

(4) due to space constraints, the oil tank is smaller and heats faster

(5) the star gear adopts a gear oil separator. Due to the large pressure impact, the ability to correct the eccentric load is poor, which is easy to leak oil and has a short service life

(6) the system adopts valve controlled throttling speed regulation, with large energy loss

(7) since the system adopts domestic hydraulic components, the manufacturing and maintenance costs are low

in the 21st century, hydraulic technology has developed rapidly, and load sensing technology has been more and more widely used in construction machinery

4 characteristics of the new roadheader hydraulic system

the new roadheader hydraulic system adopts a load sensitive control system composed of a load sensitive variable pump and a load sensitive proportional multi-channel valve. The system has the following characteristics:

(1) in the non working state of the system, the common load LS signal channel on the multi-channel valve passes through the T port for pressure relief, and there is no pressure signal from the flow of the pump to the LS on the pressure controller, At this time, it is regarded as a no-load state. Under the action of 2 ~ 3 MPa pressure, the swashplate of the pump makes the pump at the minimum swing angle. The pressure at the minimum swing angle of the pump is determined by the characteristic curve of the spring installed in the pressure flow controller. Generally, the pressure is adjusted to 2.5 MPa when leaving the factory, and the overflow flow of the pump is about 2 ~ 4 L/min. In this way, the power loss of the system in the non working state is small, and the empty circulation volume of the system oil is less, which can improve the service life of the oil. During shutdown, the swashplate of the pump reaches the maximum swing angle under the action of the return spring

(2) the system adopts imported v30d140 load sensitive double variable pump, equipped with psv552/type 7-GANG and psv55/type 4-Gang, two groups of load sensitive proportional multiple valves, and one pump is equipped with one group of valves. The system pipeline configuration is simple, compact and clear, which is convenient for assembly and maintenance

(3) the system can control the flow of the actuator independent of its changing load, that is, no matter how the load changes, The actuator can be tested, and the tensile test will be carried out in the set steps (if the extensometer is installed, the constant flow will be obtained after the software prompt is removed. At the same time, multiple actuator elements can work at the same time, and the pressure and flow will not be affected each other. That is to say, the four actions of two star wheels, the first transportation and one water spray on the four-way valve generally work at the same time for a long time, and they are all motor-driven. There is no frequent commutation, which will not affect the stability of work operation. The control mode is manual positioning. In this way, when working After the handle is pushed to the reversing position, it will not move, and then other operations can be carried out

7 the first two units on the combined valve are used for running, and the flow is generally 80 l/rain. Others are cutting head lifting, cutting head rotation, shovel plate lifting, rear support, cutting head expansion (or anchor bolt machine), and their flow is basically 60 L/min. In arranging the sequence of actions, the walking with synchronization requirements is considered to be placed in the first and second links. Due to abundant flow and small resistance, the synchronization accuracy is high. Considering the pressure loss in the valve, the frequent actions are arranged forward and infrequently behind, and several actions can work at the same time

(4) the LS port pressure signal of the valve is the working pressure in each group of valves. The maximum pressure value is obtained by comparing the shuttle valves. The LS ports of the two groups of valves are connected to the LS ports of two load sensitive variable displacement pumps respectively. The flow pressure controller of the pump can control the swing angle position of the pump according to the total flow required by the actuator

(5) when traveling, use the 4 MPa pressure at the Z port of PSV valve to turn on the traveling motor. At this time, the stress is proportional to the strain. There is no need to control the oil source additionally and save a gear pump

(6) the imported PSV proportional solenoid valve has passed the national mining safety certification, and the safety mark number is j; J。 Prepare for the electric control or remote control of the roadheader

5 summary

the hydraulic system of the improved roadheader has stable and reliable performance, low failure rate and high work efficiency, which has been highly praised by users. At present, the hydraulic system design of domestic roadheader has its own characteristics, but basically, the hydraulic system form of load sensitive variable pump plus load sensitive proportional multi-channel valve is adopted, and the control mode adopts manual proportion or hydraulic proportion. But the general development trend is to develop in the direction of remote control. At present, the hydraulic system of foreign roadheader has been very mature in the form of remote control. It is believed that the domestic remote control roadheader will also be born soon. (end)

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