Due to the different design level, manufacturing quality, use environment, maintenance technology and management level of users, the service life of the same type of equipment varies greatly. The author has been engaged in the maintenance management of construction machinery for decades. Based on my many years' working experience and feelings, from the whole process of research, design, manufacture, installation and maintenance of construction machinery, the author talks about the necessary measures to extend the service life of machinery reasonably and improve the management level, so as to ensure the normal service life of construction machinery and give full play to its due benefits.
1, the influence of design on the life of construction machinery
1. 1 should be adopted to optimize the design, so as to ensure the proper service life.
Excellent design is the first link to prolong the service life of machinery. Japan, the United States and other developed industrialized countries put forward the idea of "designing for occupation", demonstrated the advantages and disadvantages of design in various ways, and chose the best optimized design scheme. In this way, their products are durable, efficient and low-consumption, thus occupying the main construction machinery sales market in the world. The main mechanical equipment of earthwork in China's large-scale construction projects mainly adopts the products imported from the above-mentioned developed countries, with novel appearance, comfortable operation, advanced performance and durability. Its ergonomically designed seat, console, environmentally-friendly low-noise engine, advanced streamlined fuselage and driving comfort have good mechanical properties and humanized design, which are well received by pilots. For example, the hydraulic excavators produced by Caterpillar Company of the United States and Komatsu Company of Japan are well received by users. According to the product design data analysis of Japanese manufacturers such as Komatsu and Kobe Steel, in order to ensure the service life of mechanical design, the main methods are to implement feasible design and convenient maintenance design. However, Caterpillar Company of the United States used the load analysis method to accurately analyze the stress of the stressed parts of excavators and bulldozers during construction, and put forward the design of prolonging the life of the parts (long life design). The ideas are as follows: first, reduce the surface pressure (contact stress on the surface of parts), such as replacing involute gears with spiral gears, which greatly increases the gear overlap coefficient; Secondly, the load is dispersed. Bulldozer adopts triangular crawler system instead of traditional parallel crawler system, and moves the driving wheel from the conventional touchdown to the top of the triangle without touching the ground, which greatly reduces the resistance of impact load, working load and soil to the crawler transmission pair. Thirdly, anti-wear design, such as using wet clutch and wet brake, can reduce friction loss and improve mechanical transmission efficiency and energy utilization. Because of their successful optimization design, their products have strong competitiveness and high market share after being put on the market.
1.2 design considerations for maintenance
Hitachi Construction Machinery believes that "low-cost quick repair" can be used to keep the parts in good technical condition if the machinery is maintainable and easy to maintain. The construction machinery designed in this way can be quickly repaired at low cost without replacing new parts and components, which actually prolongs the service life of the machinery, improves the integrity rate of the machinery and reduces the use cost of the machinery. Therefore, on the basis of traditional optimization design, the following factors should be considered emphatically to facilitate maintenance.
First, it simplifies the disassembly and assembly, making the maintenance workspace convenient and humanized. For example, OPS pipe joints, separated links, tilting cab and hood, hinge structure with adjustable clearance, etc. The second is the combination of parts, which are designed to be easy to disassemble, such as CATD9L bulldozer. Due to the component combination design, the disassembly time is shorter than that of CATD9H bulldozer. Third, the lubricating oil is concentrated. For example, in the bulldozer produced by Komatsu Company in Japan, the fuel inlet (oil filter) and pressure measuring point of the transmission, torque converter and other components are arranged in one place, so that the driver can refuel the above components and check the oil level at the same time when standing on the ground, avoiding the fatigue of climbing up and down, which is conducive to ensuring lubrication on schedule and preventing the inspection parts from missing; Fourthly, the hydraulic oil is filled in a sealed way to completely prevent harmful molecules such as sand and other impurities from entering the hydraulic oil in the construction environment. For example, BARTMIL 160 asphalt pavement milling machine made in the United States has designed a device for sealing and filling hydraulic oil to ensure the cleanliness of the oil injected into the hydraulic system; Fifth, check electronic monitoring, and use electronic sensing technology to monitor oil quantity, oil temperature, shaft temperature, water temperature, vibration and load to prevent problems before they happen; Sixth, extend the lubrication cycle, such as using double filters to make the oil not easy to age, and using oil-bearing for the articulated parts of the rod system with light load and infrequent activities to realize ideal lubrication; Sealing lubrication is adopted to reduce the aging and leakage of oil, which not only prolongs the lubrication cycle and reduces the maintenance workload, but also ensures that the parts are in a good lubrication state; Seventh, the wearing parts should be generalized. For commonly used vulnerable parts, try to use commonly used parts to reduce spare parts reserves and facilitate spare parts procurement. Eighth, the random tools are complete. Due to the particularity of the construction machinery operation site, it is necessary to design more comprehensive random tools to facilitate the driver's daily maintenance and general troubleshooting. Nine is to consider the durability of sports pairs as much as possible and reduce frequent maintenance items.
1.3 adopting new materials
Construction machinery made of new materials can effectively prolong the service life of machinery. In recent years, the development of materials science and technology has advanced by leaps and bounds. A large number of high-strength, wear-resistant, earthquake-resistant and impact-resistant new materials, nanotechnology materials and advanced electronic component technologies are constantly emerging. When designing machines, new materials should be selected according to their mechanical properties and working conditions to ensure their service life from the aspects of material properties and quality. This can control the performance of mechanical parts from the source, reduce frequent maintenance items, make maintenance operation simpler and more convenient, and lay a solid foundation for prolonging the service life of machinery. For example, the electric valve for lifting limit of 40t asphalt concrete mixer produced by Quanzhou Pavement Machinery Factory in Fujian Province has greatly reduced the failure rate (it has been reduced to zero since it was used for four years) due to the adoption of advanced imported components.
2. Manufacturing and production
In order to ensure the quality of mechanical equipment and make it durable, manufacturers should establish a strong quality assurance system, improve quality awareness and strengthen production process testing (this is also an ideal product for designers), and unqualified parts must never be assembled on the main engine. Strict quality acceptance system should also be established for foreign cooperation parts. Otherwise, although the quality of the main engine and main assembly parts is good, the quality of some parts produced by the cooperative manufacturers can not meet the design requirements, resulting in frequent failures of the whole machine. For example, the "BARTMIL 160" road milling machine imported from the management section of Kaiyuan Highway in Yunnan in 1998 was replaced twice continuously because the quality of the rear steering hydraulic cylinder was not up to standard, and the fault was not eliminated until the foreign businessmen sent people to the site to repair and replace the parts, which not only increased the maintenance workload, but also affected the reputation of the manufacturer. Therefore, the assembly plant should strictly accept the outsourced parts according to the specifications, and unqualified outsourced parts are not allowed to assemble the main engine. In addition, products with immature mechanical design and unstable performance should not be put on the market, otherwise it will damage the market image of the enterprise.
3. Use and maintenance.
The service life of construction machinery is long and short, and the management and use of users is a very important part. We should do well in the following four aspects.
3. 1 Adhere to the system of "two guarantees and three guarantees"
Assign personnel and machines to use, store and maintain packaging). Mechanical operators should have "three understandings" (structure, principle and performance) and "four skills" (operation, maintenance, inspection and troubleshooting). Correct use of machinery, strict implementation of safety technical operation procedures, target cost management of machinery and equipment, and economic benefits of operators are linked to machinery use fees (such as fuel and material fees, maintenance fees, maintenance fees, material fees, tool fees, etc.). ), and change the passive daily maintenance of mechanical drivers into active daily maintenance.
3.2 Reduce the invisible wear and tear of machinery caused by environmental climate.
That is to reduce the influence of environmental factors on the service life of machinery. Because construction machinery is mostly operated in the open air, the working place often changes, and its performance is greatly affected by the temperature, environment, climate and other factors in the working place. For machinery that has been fixed for a long time, the machine room (shed) should be stopped, or maintenance measures such as covering and using wooden mats should be taken to reduce invisible wear caused by sun, rain and corrosion. Many construction units ignore the influence of environmental factors on the use of machinery (too low ambient temperature will also have disastrous consequences for machinery). Failure to take corresponding protection or adaptation measures will reduce the performance of machinery, shorten its service life and even lead to accidents.
3.3 Regular maintenance of machinery is the key to prolong life.
The Maintenance Regulations of Highway Maintenance Machinery issued by the Ministry of Communications clearly stipulates the maintenance of machinery. However, in the case of tight schedule and heavy tasks, many construction units often ignore the maintenance work and think that the machinery is running normally and there is no fault, so there is no need to stop for maintenance. This has laid a hidden danger for future mechanical accidents. Because maintenance can eliminate mechanical hidden dangers, if maintenance is not timely, it will often lead to major failures of mechanical equipment, and even accidents of personal injury and forgetting. This not only increases the maintenance cost, but also delays the construction period.
3.4 Adopt advanced auxiliary maintenance means such as mechanical inspection.
Mechanical maintenance is an important link to prolong the service life of machinery, and reasonable maintenance methods can effectively prolong the service life of construction machinery. According to relevant statistics, advanced condition monitoring means can reduce the maintenance cost by 25% ~ 50%, reduce the failure rate by 75% and prolong the service life of machinery.
3.5 Low-cost rapid repair method
The "low-cost quick repair method" proposed by the machinery industry is also an effective method to prolong the service life of machinery. To implement this method, in addition to adopting maintainability design in mechanical design to improve the maintainability of machinery, the following methods can be adopted in maintenance practice: 1. Transposition of parts. Many parts of construction machinery, such as bulldozer, crawler pin of excavator, cylinder liner of diesel engine, etc. In the process of operation, it often bears unidirectional load, which leads to uneven wear. If the position of parts under unbalanced load is changed in time to make them wear and balance, their service life can be prolonged. Secondly, advanced brush plating and bonding repair technology can also repair failed parts quickly and at low cost.
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