2 In the maintenance mode of regular inspection and maintenance and active maintenance prevention and maintenance, the active maintenance prevention and maintenance are compared with the former two, which can effectively prevent malfunctions and prolong the service life of the equipment. The specific application of active maintenance and maintenance in the maintenance of hydraulic system is introduced.
Min Key Words Periodic Inspection Inspection Maintenance Maintenance Maintenance Maintenance Hydraulic system maintenance is a series of measures to prevent machine failure and premature failure to ensure reliable operation. The proactive maintenance prevention and maintenance proposed here is a new strategy for the rise of maintenance technology engineering in recent years, and it is the biggest source of benefits for contemporary enterprise projects.
Proactive maintenance and maintenance new strategies The current maintenance methods are mainly the following.
Regular maintenance. According to the machine fault file data and failure trend analysis, regular repair and maintenance are carried out according to the working hours or the number of kilometers per year or the number of cycles. However, regular maintenance has problems with over-maintenance or insufficient maintenance. According to statistics, the cost of regular maintenance is wasted.
Inspection and repair. Through instrument monitoring and expert analysis and decision making, repairs occur before the machine fails. The monitored content is an early failure sign that reflects material wear and performance degradation, such as abrasive grain content and characteristics in the oil, and system vibration and noise temperature rise. According to the failure symptoms, the degree of failure and the fault location can be diagnosed, and a warning is issued in advance to take maintenance measures to avoid serious downtime.
Proactive maintenance and preventive maintenance. Proactive maintenance Preventive maintenance is the maintenance activity that takes place before the machine begins to experience worn material wear and performance degradation. It monitors the root cause parameters of the system failure and corrects abnormal conditions in time to maintain the good working condition of the machine, such as the physical and chemical properties of the oil pollution degree and temperature. Through maintenance measures, the basic parameters of the failure root cause are within the allowable range to prevent the occurrence of failure and extend the life of the component.
The difference between protection and inspection maintenance can be seen from the failure curve of 1. The purpose of proactive maintenance maintenance is to maintain the curve level before the failure occurs. Maintenance range Detection and maintenance range Maintenance and maintenance The scope of this scope is to extend the life of the machine to extend the life of the machine.
Hydraulic System Failure Roots Hydraulic System Active Maintenance The primary part of preventive maintenance implementation is to clarify the root cause of failure.
The root causes of hydraulic system failure are as follows: fluid pollution; 2 fluid leakage; 8 fluid chemical property changes; 4 fluid physical property changes; 5 fluid cavitation;
In order to prevent the hydraulic system from failing, the above root parameters must be monitored and corrected to keep them within the allowable range.
Failure development process root cause parameter abnormally abruptly completely stop working part of the function Na, + force repair scrap preparation, shutdown maintenance, replacement of damaged components, monitoring of material wear monitoring and correction of root-cause parameter performance reduction measures fluid pollution. Fluid contamination is the main source of failure in hydraulic systems. According to statistics, about 75 hydraulic system failures are caused by fluid pollution, and the main forms of failure are pollution wear pollution and pollution blockage.
The main factors affecting the wear and performance degradation of hydraulic components are the contamination sensitivity of fluid contamination components and working conditions. In order to prevent failures and failures caused by fluid contamination, it is necessary to control the degree of contamination of the fluid in the system within the tolerance of critical components, that is, to stabilize the degree of fluid contamination.
leakage. Leakage is a common problem in hydraulic systems. External leakage occurs on the outer joint surface of the hydraulic component and the linear and rotary motion interfaces. The internal leakage occurs at the gap of the internal movement of the hydraulic component, such as the hydraulic cylinder of the hydraulic pump and the sealing gap of the piston. Excessive internal leakage causes the volumetric efficiency of the crucible to decrease the speed of the hydraulic cylinder crawling hydraulic Motor, etc., which is a great hazard to the hydraulic system.
Leakage is a signal of failure and failure of the hydraulic system and countermeasures must be taken in a timely manner. The main cause of the leakage of the hydraulic system is the wear of the seal or the looseness of the damaged pipe, causing looseness, and poor hose processing or installation. Reasonable sealing structure The sealing force necessary for the sealing material is an important factor to ensure the stability of fluid leakage. By controlling the temperature rise of the hydraulic system and the excessive vibration, it is possible to reduce internal and external leakage.
Changes in fluid chemical properties. Fluid chemistry is related to its base ingredients and added chemical composition. In order to improve the performance of the fluid to meet the working requirements of the hydraulic system, various chemical additives such as anti-oxidation, anti-rust, anti-adhesive, anti-wear and low-condensation additives are added to the working fluid, and the chemical stability is ensured to ensure the reliable operation of the hydraulic system. Important conditions for component life.
The fluid is affected by high pressure and adverse environment in the system, and its chemical composition and performance will gradually change during work and storage, which is mainly caused by oxidation of the fluid and consumption of additives. As a result of this oxidation reaction, the fluid is degraded, and soluble and insoluble compounds such as resin acidic substances and precipitates are produced, and the progress increases the contamination of the fluid.
The rate of fluid degradation is related to factors such as the type and amount of pressure at the working temperature. When water and metal particles acting as catalysts are present at the same time, the oxidation rate of the oil increases sharply, and iron and copper respectively accelerate the oxidation rate of the oil by about 10 times and 30 times. Therefore, effective control of oil contamination, the use of additives to stabilize the oil, helps to maintain chemical stability.
Changes in the physical properties of the fluid. The physical properties related to the operation of fluids and hydraulic systems are mainly viscosity viscosity index shear strength bulk modulus of elasticity saturated vapor pressure gettering and water content. These physical quantities vary with system conditions such as mechanical agitation and shear of the chemical composition of the pressure temperature fluid, as well as the type and concentration of contaminants. When the influence and interference factors disappear, the physical properties of the fluid can be restored to the original value, and the physical properties of the fluid are considered to be stable.
However, when the fluid undergoes chemical decomposition, the resulting change in physical properties is unrecoverable. Changes in the physical properties of the fluid beyond the allowable range will cause damage to the system and components. Therefore, maintenance personnel of the hydraulic system must pay attention to changes in the physical properties of the fluid to maintain its stability.
Liquid cavitation. When the hydraulic system is cavitation, it will cause vibration and noise, accelerate the deterioration of the oil, and deteriorate the performance of the hydraulic system.
The fluid system is overheated. The operating temperature of the hydraulic system should have a fixed range, the temperature over the fluid viscosity becomes lower, the lubrication performance deteriorates, the leakage increases, and the fluid oxidizes and decomposes. If the temperature is too low, the viscosity of the fluid increases and the fluidity deteriorates. Exceeding the allowable range of temperature also has a great influence on the performance of the sealing material and the component. The flexibility of the rubber elastomer at low temperature is deteriorated, the strength of the material is weakened under temperature, and the thermal expansion is liable to cause the movement of the component to be hindered or clamped. Therefore, it is important to control excessive changes in the operating temperature of the hydraulic system.
The practice of proactive maintenance prevention and maintenance shows that the main source of failure of hydraulic systems is fluid pollution. Fluid contamination wear causes hydraulic system leakage and overheating, and fluid physical and chemical properties are degraded. Therefore, oil pollution monitoring and control is the main technical measure for active maintenance and maintenance of hydraulic systems. In addition, it is important to periodically check the changes in the physical and chemical properties of the oil to maintain its stability.
The following steps should be taken to implement proactive maintenance prevention and maintenance with pollution control as the main content.
Determine the level of cleanliness of the hydraulic system required to achieve life expectancy and operational reliability, ie target cleanliness.
Select and improve the filter unit to confirm the filter accuracy of the filter element.
8 Regularly check the pollution degree of the hydraulic system oil. If the allowable range is exceeded, corrective measures should be taken in time to achieve the target cleanliness.
In order to effectively carry out active maintenance and preventive maintenance, the results of monitoring and maintenance monitoring should also be utilized, such as grinding shoulder vibration analysis, pump and motor speed, and system overheating. In actual maintenance work, proactive maintenance and preventive maintenance are combined with predictive maintenance. By monitoring the root cause of failure and the signs of failure, the life of the hydraulic system can be extended to prevent malfunction.
The company's communication address is located in Yuetang District, Xiangtan City, Hunan Province. The explosion-proof kilovolt-level cable fault point detection instrument is jointly developed by Shandong University of Science and Technology and Zhangzhou Mining Group Corporation Baodian Coal Mine. Accurately detect faults such as cable grounding and phase failure. The cable accident in the coal mine face is greatly reduced.
According to statistics from relevant departments. Mine cable accidents account for more than 50 of the entire electrical accident. The mining work surface and the following rubber cables are often more difficult to move due to the movement of the equipment. At present, when the low-voltage cable of the mining face fails, the cable should be pulled to the ground for treatment. The newly developed explosion-proof kilovolt-level cable fault point detection is obvious, and the working principle is. When the data processing system receives the command to transmit the pulse, it immediately starts the ultra-high-speed data acquisition unit to record the transient signal; at the same time, it sends a pulse to the core of the cable under test, and the speed data acquisition unit records the waveform of the reflected pulse at the fault point; the data processing unit pairs The collected data is processed according to a predetermined procedure.
The distance to the fault point can be measured. According to the received signal, the instrument can make an amplifying circuit, and it is judged whether it is suitable for fault click or not. It can automatically calculate the distance of the fault point and is convenient to use. The instrument can be used to find various cable faults used in fully mechanized mining face equipment. Li Jianfeng China Fly
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