Current situation and measures of repair and maint

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Abstract: combined with the current situation of maintenance and repair of construction machinery in China, this paper summarizes the main problems existing in the current maintenance of construction machinery, discusses the maintenance and repair measures, and puts forward some suggested maintenance methods

with the continuous improvement of the mechanization level of construction, construction machinery has become a key factor affecting the progress, quality and cost of the project. Ensuring that the construction machinery on the construction site is often in good condition, improving the utilization rate and prolonging the service life is an important link for construction enterprises to improve economic benefits and enhance their competitiveness. Various mechanical equipment required for construction is also an important guarantee to ensure the normal and smooth progress of road and bridge construction

I. Development Status of technical maintenance of construction machinery

1 Construction machinery construction operation characteristics

(1) construction is greatly affected by seasons

(2) the construction is assault. Surprise operation has greatly improved the daily working hours of machinery, the utilization rate during the construction period, the timely maintenance of machinery and equipment, and the long working hours under heavy load

(3) the working device and traveling mechanism are seriously worn. Most of the working objects of construction machinery are soil, sand or other engineering construction materials. The construction site is dusty or mud everywhere, which will aggravate the wear of the working devices and walking mechanisms of construction machinery

(4) poor climatic conditions. The weather conditions of field construction are extremely bad, and too high or too low temperature will make the work of construction machinery unstable. Too high temperature will overheat the engine and hydraulic and hydraulic transmission systems, reduce efficiency, and aggravate wear due to poor lubrication; Too low temperature will make the viscosity of hydraulic oil and lubricating oil too high, making it difficult for the engine to start, and the power loss of machinery due to friction will increase

(5) poor geographical conditions. Generally, the construction is carried out in the field. There is no road on the construction site. The uneven ground causes the machinery to run bumpily, vibrate violently, and the driving mechanism slips seriously. Tires and tracks are severely worn. If the terrain is complex, the machinery turns and rotates frequently during operation, which accelerates the mechanical wear and damage. The thin air in the plateau makes it difficult to start the construction machinery, and the power decreases: the ultraviolet intensity in the plateau is high, causing the hose of the hydraulic system to age easily

(6) the lubrication condition of the working parts is poor. The climatic and geographical conditions of construction make the lubrication of construction machinery unreliable. The high temperature makes the viscosity of lubricating oil drop, the oil pressure drop, and the lubrication is unreliable. If the temperature is too low, the viscosity of the lubricating oil increases, and the oil is not easy to reach the lubricating parts, and the lubrication effect is also poor: the amount of dust in the air of the construction site is large, which increases the impurities of the oil. If the temperature is too high, the oxidation of the oil will be accelerated, which makes the quality of the lubricating oil worse. The surface of the machine is often covered with dust and dirt, which increases the difficulty of lubrication

2. The necessity of maintenance of construction machinery

the purpose of technical maintenance of construction machinery is: ① to ensure that the machinery is in good technical condition, reduce failure downtime, improve the integrity and utilization rate of construction machinery, and ensure the progress of the project. ② Slow down the mechanical wear, increase the repair interval, and extend the service life of the machinery. ③ Avoid mechanical accidents and ensure safe production. ④ Reduce the operation and maintenance costs of machinery, improve the power and economy of machinery, and minimize the power, fuel and lubricating oil, parts and various consumable materials of machinery. Therefore, the construction machinery must be maintained in a planned way

II. Development status of construction machinery maintenance

(1) reuse and light maintenance: some enterprises have insufficient understanding of the importance of equipment management and maintenance, short-term behavior in equipment use, equipment operation with defects, parts over limit wear, especially ignoring the necessary maintenance work of equipment; As a result, equipment failures increase, service life is shortened, and economic benefits are reduced

(2) heavy repair and light modification: repeated repair of backward equipment without necessary technical transformation will not only increase the maintenance cost and become the mainstream of the market again, but also make it difficult to restore the original performance and accuracy, and can not compensate for the corresponding losses, which will hinder technological progress and cannot meet the needs of production development

(3) poor maintenance conditions: mechanical maintenance is still in the decentralized and backward state of manual operation

(4) lack of accessories: the equipment liquidity of construction enterprises is large, and the downtime of construction machinery is prolonged due to the lack of inventory of required parts, the lack of accessories in the local market and inconvenient transportation

(5) insufficient mechanical technical force: the increase and renewal of imported and domestic equipment have increased the technical requirements for equipment management, operation and maintenance personnel, but the existing personnel can not meet the development needs, resulting in the lagging situation of equipment maintenance management, and can not meet the requirements of using modern construction machinery

(6) the fault maintenance and detection technology is backward: in on-site maintenance, the judgment of construction machinery fault is mainly based on experience and sensory judgment of fault location, with low accuracy and difficult to determine the degree of fault

III. key points of construction machinery maintenance

(1) prepare a practical maintenance plan: when preparing a maintenance plan, you must master the engineering tasks, construction plans, equipment conditions, operating hours, maintenance cycle, maintenance operation time and other information

(2) determine a reasonable maintenance organization form: in order to ensure the normal operation of on-site construction machinery, on-site maintenance organization must be established. The reasonable organization form should be determined according to the actual situation of the construction. When the project is large in scale or the construction period is long, a temporary maintenance station can be set up to be responsible for the equipment maintenance of the project; When the quantity of oil injected at one time is about 24 kg, or the construction period is short, or the construction sites are scattered, engineering repair vehicles can be set up, and mobile maintenance teams can be organized to carry out patrol maintenance

(3) allocate appropriate maintenance forces: maintenance forces include equipment and personnel. The type of equipment maintenance can be determined according to the process needs, and the quantity is generally 10% - 20% of the construction machinery; Maintenance personnel are generally 1/3 ~ 1/4 of the number of drivers on duty

(4) adopt reasonable operation mode: at present, the commonly used maintenance operation mode includes comprehensive maintenance mode and professional division operation mode, which can be selected according to the actual situation

(5) adopt efficient repair methods: generally, there are single machine repair methods and assembly exchange repair methods. The single machine repair method has long repair time and unstable repair quality. It is only suitable for repair centers with weak repair force, few repair tasks and complex models; Assembly exchange repair method is currently recognized as the best method of on-site maintenance, which is to remove worn parts or assemblies, replace them with new products or repair parts, repair the replaced parts or assemblies under economic and reasonable conditions, and put them into storage for standby after passing the inspection. By adopting this repair method, the medium repair can be cancelled, the repair level can be simplified, the repair speed is fast, and the time is short, so the intact rate and attendance rate of the equipment can be greatly improved, the economic benefits of the use of the equipment can be increased, and the favorable conditions for professional maintenance can be created

IV. repair and maintenance of construction machinery during non construction period

during the construction repair and intermittent period, the construction unit generally repairs and maintains various construction machinery during this period. Before the repair and maintenance, the relevant personnel should ask the operator or driver about the problems related to the repair and maintenance, and understand the use of the machine in the previous service period, so as to focus on the key points in the process of repair and maintenance, make correct judgments, and truly eliminate various faults. In the process of repair and maintenance, relevant personnel should be careful. In addition to accurately finding the fault and carrying out repair and maintenance, they should also consider the additional impact caused by the operating environment and operating temperature difference

v. maintenance of construction machinery during the construction period

daily maintenance of construction machinery generally includes cleaning maintenance, lubrication maintenance and solid maintenance. During the construction period of road and bridge construction, the corresponding repair and maintenance methods of construction machinery are also different because of the different operating environment and operating temperature. For cleaning and maintenance, it is generally OK to do the cleaning work according to the normal cleaning time interval of the construction machinery, but if there is too much dust or dust in the working environment, the cleaning and maintenance time interval will be shortened. For example, the cleaning of air filter elements and oil replacement work should flexibly change the cleaning interval according to the amount of dust in the working environment

lubrication maintenance is also one of the most basic daily maintenance contents. When the construction volume is large, the project progress requires that the operation time of various construction machinery should also be increased, and the lubrication and maintenance should also be increased with the operation time of construction machinery, such as the lubrication of transmission system. Fastening and maintenance is an important content to ensure the safe operation of construction machinery. When the working environment is uneven and the road surface is uneven, the connecting parts of various parts of the machine are easy to loosen. At this time, more fastening and maintenance times are required than usual to prevent the occurrence of various mechanical accidents

in addition, if the surrounding environment is too wet, whether the construction machinery is in operation or not, the chassis of the machinery should be lubricated and maintained more carefully to prevent rust and decay in all parts of the chassis

VI. there are problems in the maintenance and repair of construction machinery at present.

with the continuous growth of the technical content of construction machinery, the maintenance technology of construction machinery has also developed rapidly. Various maintenance technologies greatly facilitate the work of maintenance technicians, and greatly improve the timeliness and accuracy of maintenance. However, at this stage, the detection means, maintenance and repair technology of the construction site are far from meeting the actual needs. But it is far from meeting the actual needs. This is caused by the following reasons:

(1) the detection equipment is imperfect. Due to the lack of detection equipment, the detection of construction machinery faults by construction machinery maintenance personnel remains at the stage of experience judgment. The traditional detection method of judging the fault location by experience and senses has low accuracy and is difficult to determine the fault degree

(2) the detection and diagnosis of engineering machinery faults by many construction units is still in the stage of experience judgment

(3) the technical force of maintenance on the construction site is weak

(4) the level of construction machinery maintenance technicians is limited

(5) the construction site has great mobility and limited conditions

(6) the construction site is lack of accessories

the liquidity of the construction site is strong, so it is impossible for the site to reserve all accessories, and it is absolutely not allowed to reserve all accessories when making the project budget. The general practice is to reserve a certain amount of vulnerable parts, which can also be used as short-term process and consumables for energy transmission from the outside to a layout system, while other expensive parts are generally purchased temporarily. Because the construction site is often located in a remote place, the transportation is inconvenient, the procurement of accessories is difficult, and the ordering time of accessories is long, which prolongs the downtime of the equipment

VII. Conclusion

as the repair and maintenance of construction machinery belongs to the interdisciplinary research field, many factors are involved, and many factors are complex and intertwined, which makes this problem more challenging. In the absence of rich investigation data and practical experience, it is difficult to get very satisfactory results. In fact, many experts and scholars at home and abroad are also doing the same research work and have made many achievements, which can only be said to be of great significance

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