In the process of machinery use, phenomena such as wear, deformation, fatigue, or corrosion will inevitably occur, which will reduce the dynamic performance, economic performance and safety and reliability of the machinery. When these changes reach a certain limit, the machine cannot work normally. For this reason, maintenance must be carried out in accordance with the law of changes in mechanical technology.
Whether the technical performance of road building and maintenance machinery is often maintained during the construction process depends to a large extent on its reasonable use. As the operating time or mileage of the machinery increases, its technical performance is inevitable. Changes have occurred due to the natural wear and tear between the mechanical parts and parts, as well as some failure to comply with the mechanical technical use and maintenance procedures. If the parts of these machinery are not lubricated, adjusted, inspected and other technical maintenance operations are performed in time, the wear of the parts of the mechanism will increase sharply, which will result in the deterioration of the power performance of the road construction and maintenance machinery, the increase in fuel consumption, and the work Reliability is reduced, causing other failures and damages, and the entire machine loses its working ability, affecting the normal use of the machine. The main way to reduce and prevent the wear of mechanical parts is to carry out technical maintenance in time. The so-called maintenance is to clean, lubricate, tighten, check, adjust or replace certain parts of the machinery regularly.
The purpose of maintenance of road construction machinery is in the following three aspects: 1) to ensure the normal operation of the machinery; 2) to extend the service life of the machinery; 3) to reduce the cost of machinery use.
The purpose of machine maintenance is the following five aspects:
① Keep the road construction and maintenance machinery always in good condition so that they can be started or run at any time;
②Under the conditions of reasonable use, it will not stop due to damage to the parts in the middle;
③Do not affect safe construction or driving due to mechanical accidents;
④ Maintain a balanced technical status of the entire road construction and maintenance machinery and its various assemblies to achieve the longest overhaul interval;
⑤ Make fuel, lubricating material, tires and parts reach the lowest consumption.
Through the above introduction, everyone has learned the role of repair and maintenance of road construction and maintenance machinery, but there are differences between the two, mainly in:
①Different in nature: Mechanical maintenance is a preventive technical support operation performed before the mechanical parts have reached the limit of wear to keep the machine in normal working conditions, while mechanical maintenance is performed when the mechanical parts reach the limit of wear and cannot work normally Restorative technical support operations to make the machinery reach normal working conditions again;
②The content of the operation is different; the content of the mechanical maintenance is the "cross operation" of cleaning, fastening, lubricating, adjusting, and anti-corrosion without changing the geometric dimensions and physical and chemical properties of the parts. The main content of mechanical maintenance is to change the geometric dimensions, physical and chemical properties and assembly clearance of parts. Although mechanical maintenance operations also include maintenance operations, they are not the main content and are different from the scope of regular maintenance;
③The process is different. The mechanical maintenance process is to dismantle all the machinery or assembly, appraise all parts and repair or replace as required. The mechanical maintenance only carries out partial disassembly, and does not carry out identification and repair of parts;
④ The principles are different. Mechanical maintenance is carried out on the principle of regular maintenance and mandatory. Mechanical maintenance implements the principle of planned repair and on-demand.
The following describes the situations encountered in actual work one by one:
1. The content of mechanical maintenance
There are many tasks for mechanical maintenance, including restoring the geometric shape, geometric dimensions, roughness, physical and chemical properties and assembly technical conditions of the parts. At the same time, maintenance work is carried out on repaired parts and prescribed parts. When repairing, the parts to be repaired must be disassembled, cleaned and identified according to the scope of repair. Parts in the scope of exemption should be kept, repairable parts should be repaired, scrap parts replaced, and re-assembled according to technical standards, and then trial operation and overall inspection should be carried out to meet the requirements After the performance parameters, the repair is completed. Repairing repairable parts includes "welding, repairing, spraying, plating, riveting, inlay, matching, expansion, shrinking, correction, sticking, and modification" 12-character repairing methods.
2. Operation method of maintenance of road construction machinery
2.1 Adjustment method Many machines are designed and manufactured to take into account the adjustment of some parts, such as the valve lifter of the engine valve mechanism and the oil pump lifter of the high-pressure diesel pump. The relative position of the screw and the nut can be changed to maintain the tappet regulations. length;
2.2 Transposition method The wear of mechanical parts is uneven. When the working part of the part is worn too much and needs to be repaired, and the other parts of the part are not worn, replace the unworn part of the part to the working part to restore the machine to normal operation The method is called transposition method. For example: the drive wheel of the crawler tractor and the drive gear of the steering clutch, due to the long time going forward, the wear is mostly concentrated on one side of the gear teeth, and it can be used in reverse in maintenance;
2.3 Repair size method Use repair size method to restore worn fittings is to process one part in the fit to make it have the correct geometric shape, and replace another part according to the size of the processed part to restore the work of the fitting ability. For example, after the engine cylinder is worn out, it can be repaired according to the size, and the enlarged piston can be replaced;
2.4 Additional parts method When the mating parts wear out, the mating parts are processed separately to obtain the correct geometric shape, and then an additional part is added to the fit to restore the original fit, which is called the additional part method. For example, when the journal and the parts are worn out, the shaft can be machined to the smallest size, and the sleeve can be inserted in the hole or the sleeve can be pressed on the journal;
2.5 Partial replacement method The partial replacement method is a repair method that only replaces the damaged part of the part. For example, a gear in the gear set is seriously worn, and the worn part can be annealed and cut off. After replacing the new gear ring, welding is performed outside the joint. Repair the gear;
2.6 Restoring the size method to restore the worn parts to the original shape and size to restore the function of the fit, called the restoration size method;
According to the combined relationship between the added metal and the original parts, it can be divided into the following categories:
① Mechanical integration;
②Electrodeposition combination, relying on ions to deposit on the metal surface;
③Fusion welding, such as gas welding, electric welding, forging, etc.;
④骋濒耻颈苍驳;
⑤ Squeeze
2.7 Replacement of new parts. Parts that have been worn out and are not repairable or worthy of repair can be replaced with new parts.
3 Mechanical maintenance classification
Mechanical repairs are divided into normal repairs and accident repairs according to their damage causes and conditions, and normal repairs are divided into overhaul, medium repair, and minor repair.
3.1 Overhaul: It is a planned comprehensive restoration repair. After the machine is used to the interval of overhaul repair, most of its parts and even some basic parts have reached the limit of wear, which significantly reduces the performance of all aspects of the machine. Therefore, a comprehensive and thorough repair must be carried out, all parts are disassembled and inspected, and parts that do not meet the requirements of the overhaul or are exempted are repaired or replaced, and re-assembled according to the overhaul technical conditions to basically restore the original power performance, economic performance and machine. The sturdy performance of the parts, fully recover the machine condition;
3.2 Intermediate repair: It is a planned balance repair between two major repairs for machinery powered by internal combustion engines. After a new machine or a machine after a major repair, after a certain period of use, some assemblies wear out faster, and some assemblies wear out more slowly. This unbalanced technical condition prevents the machine from working in harmony. Therefore, overhaul the engine and other 1-2 assemblies, comprehensively perform three-level maintenance on other assemblies, and eliminate all faults found, so as to adjust the imbalance between the assemblies and restore the normal working state of the machinery. Extend the interval between overhauls as much as possible;
3.3 Minor repairs: sporadic maintenance repairs that are unplanned. It is to temporarily determine the replacement or repair of a certain part or a certain assembly according to the machine condition to eliminate the temporary failure or partial damage of the machine in use and restore the normal working condition of the machine. Minor repairs generally only replace vulnerable parts, not basic parts. Minor repairs play an important role in preventing mechanical damage and should be carried out in conjunction with maintenance. The content of the maintenance of road construction and maintenance machinery is explained above, and the maintenance content of road construction and maintenance machinery will be discussed in combination with actual work;
4. Operation content of maintenance of road construction machinery
The main content of mechanical maintenance is cleaning, tightening, adjustment, lubrication, and corrosion protection, which is called "cross operation". This is based on the law of changes in mechanical technology and the experience gained through years of practice. In addition, there are auxiliary tasks such as inspection and addition.
4.1 During the operation of the cleaning machine, it will inevitably cause dirt inside and outside of the machine, various systems and parts, and dirt on some key parts will make the machine unable to work normally. Therefore, the cleaning operation is not only the need to keep the machine clean and hygienic, but also the need to ensure the safety and normal work of the machine;
4.1.1 Clean the air filter The main function of the air filter is to filter the dust in the air entering the cylinder. When the air cleaner is working, as the degree of dirt increases, the filtration efficiency continues to decrease, and the filtration resistance increases, which causes the engine to wear out and the power drops, so it must be cleaned in time.
4.1.2 The clean oil of the oil filter is inevitably contaminated by metal chips, dust, impurities and combustion 名媛直播 produced by wear during use. At the same time, the oil itself will also produce acidic substances and colloidal deposits due to heating and oxidation, which makes the surface of the filter element more and more dirty, the filter resistance increases, the oil pressure drops, the circulation volume decreases, and the oil supply is insufficient, which cannot be guaranteed. The engine works normally and accelerates wear. Therefore, the oil filter must be cleaned in time to restore its normal operation.
4.1.3 Diesel filter cleaning The roughness and fit clearance of the main parts of the diesel engine fuel supply system are very precise. The reliability and durability of the fuel supply pump depends mainly on the purity of the diesel. At the same time, the use of clean diesel fuel can extend the life of precision parts by 30%-40%. The impurities in diesel fuel may also accelerate cylinder wear. Therefore, in addition to maintaining cleanliness when refueling, the impurities deposited in the diesel tank must be regularly released, especially the diesel filter must be cleaned regularly.
4.1.4 Clean the cooling pump When the engine water temperature is often too high, the cause should be investigated. If it is true that scale is generated in the cooling pump, it must be cleaned. Otherwise, the engine water temperature will be too high, the power will drop, and the wear will increase.
4.1.5 Cleaning of electrical equipment To ensure the normal operation of electrical equipment, electrical equipment such as motors, generators, starters, batteries, and electrical operation and electrical control parts should be kept clean; regularly remove the carbon powder on the commutator and carbon brush , And wipe the commutator as required to keep the electrical contacts clean, which is very important for the safe and normal operation of the machine.
4.2 There are many screw-fixed parts on the fastening machine. Due to the influence of constant vibration and alternating load when the machine is working, some screws may be loose, and must be checked and fastened in time. Otherwise, oil leakage, air leakage, water leakage, and electricity leakage may occur. Loose screws may also change the force of certain parts, causing parts to deform or break. Loose screws may also lead to malfunctioning, moving or falling of parts or assemblies, and even mechanical accidents. Therefore, the parts must be tightened frequently.
4.3 Adjusting the relative relationship and working parameters of many parts on the machine needs to be checked and adjusted in time to ensure the normal operation of the machine. If it is not adjusted in time, the lighter ones will cause uneconomic work, and the more serious ones will lead to unsafe mechanical work and even accidents. The adjusted content and parts are as follows:
4.3.1 In terms of clearance: such as gear clearance, valve clearance, brake band clearance, spark plug clearance, etc.
4.3.2 In terms of stroke: such as clutch pedal, brake pedal stroke, etc.
4.3.3 Angle: such as pre-ignition angle, pre-fuel supply angle, etc.
4.3.4 Pressure: such as fuel injection pressure, oil pressure, air compressor pressure, hydraulic device working pressure, etc.
4.3.5 Flow: such as oil supply.
4.3.6 Elastic aspects: such as fan belt, track elasticity and so on.
4.3.7 Tire rotation.
4.3.8 In addition, there are many contents such as voltage, current, total speed, carburetor oil level, etc., which must be checked and adjusted in time.
4.4 Lubrication
Most of the movable parts of the machine, including rotating and reciprocating parts, need to be well lubricated to ensure the normal operation of the machine.
4.4.1 The adjusted lubrication system of the engine continuously supplies a certain amount of clean lubricating oil with a certain temperature to the friction surfaces of the engine to ensure the normal operation of the engine.
4.4.2 Lubrication is also very important to maintain the normal operation of the gears of the transmission part.
4.4.3 When each part of the rolling bearing works, it also needs good lubrication. There are also some movable parts such as tie rods, pulleys, and pins that need to be lubricated.
4.4.4 There are quite a lot of lubrication points on the machinery, and the time for checking, adding and replacing lubricating grease is also different. It can be seen that lubrication is an important, heavy and meticulous work in maintenance operations.
4.5 During the use of anti-corrosion machinery, the protective layer of some metal 名媛直播 will inevitably fall off. Spray paint or grease and other anti-corrosion coatings should be applied. For some non-metal 名媛直播, necessary anti-corrosion measures should be taken, such as cleaning the rubber 名媛直播. Oil pollution, etc., should be protected.
5. Classification of maintenance of road construction machinery
5.1 Routine maintenance refers to the inspection and maintenance carried out before the start of the machine, during the period of suspension of work in the shift and after the end of the general work. Its main content is to check the vital parts and vulnerable parts;
5.2 Regular maintenance
5.2.1 The primary maintenance is mainly to maintain the intact technical condition of the machinery and ensure the normal operation during the interval between two guarantees;
5.2.2 The secondary maintenance is mainly to maintain the good working performance of each assembly, mechanism, and parts of the machine, and to ensure the normal operation of the two second warranty intervals;
5.2.3 The three-level maintenance is mainly after the machine has been running for a long time. In addition to the necessary maintenance, it is necessary to focus on a more thorough inspection to discover and eliminate hidden dangers in time to ensure the normal operation of the machine during the two three-guarantee intervals.
