Necessary for the maintenance of the hottest newsp

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Necessary for the maintenance of newspaper printing equipment

general knowledge of mechanical part maintenance

mechanical faults can generally be divided into accidental faults and natural faults. Accidental faults are mostly caused by improper maintenance or adjustment, violation of operating procedures, etc., which should be avoided as far as possible. Although natural faults are difficult to avoid, the effective working time of the machine can be extended by improving the level of use and maintenance

there are three main failure modes of mechanical parts: fracture, deformation and surface failure. The following describes the wear, deformation, cleaning methods and folding and disassembly assembly of printing mechanical parts

a) wear of printing machine parts

during the working process of the machine, if the size of the relatively moving part surface occurs? The change of shape and surface quality of new graphene materials is called wear

the main causes of parts wear are friction and molecular gravity. Wear can be divided into abrasive wear, mechanical friction wear and adhesive wear. The existence of these problems causes China's plastic machinery industry to not meet the level of foreign plastic machinery as soon as possible. The reasons for the wear of mechanical parts are generally: speed, pressure, lubrication, temperature, materials, processing and coordination

b) deformation of printing machine parts

in the process of maintenance, wear is one of the main factors of mechanical damage, but the micro deformation of parts is easy to be ignored, and the technical performance of the machine often fails to meet the requirements after the repaired worn parts are assembled. This is related to metal deformation. In actual production, the deformation of basic parts should be paid special attention, because if the basic parts are deformed, it will affect the relationship of all parts assembled on the basic parts and the mechanical performance of the mechanism. Therefore, in the process of parts repair, it is necessary to check both the wear of the mating surface and the mutual position of the parts (especially the basic parts). At the same time, users can be provided with a variety of experimental schemes and data processing methods according to GB, ISO, JIS, ASTM, din and other experimental standards? For the mechanical deformation after the first overhaul, we must pay attention to whether it has deformation after 12 ~ 20 months under the action of internal stress. For hot processed parts, corresponding measures should be taken to remove internal stress

disassembly and assembly of printing machinery

mechanical repairmen who repair printing machinery must face disassembly and assembly problems, especially assembly, which will directly affect the quality of mechanical performance. The assembly quality is not high, which will cause serious wear and tear of machinery

a) mechanical disassembly

due to the large number of types of printing machines and different shapes of parts, it is difficult to describe them one by one. Here are the general disassembly principles

first, before disassembly, you must understand the structure, function and principle of the machine, and first consult the relevant technical data and instructions. From the perspective of reality, determine the parts to be disassembled. The parts that can not be disassembled should not be disassembled as far as possible, but for the parts that cannot be disassembled, we must go through the overall inspection to ensure the quality

secondly, in the process of disassembly, the external accessories, oil pipes, etc. should be removed from the outside to the inside in order. Then the disassembly should be carried out in the order of assembly first and then parts. For the matching positions of important parts, marks should be made during disassembly, numbers should be listed, and disorderly stacking should be avoided. It is also important to use tools reasonably during disassembly, and the tools must be suitable for the disassembled parts. For example, appropriate wrenches should be used to dismantle threaded connectors, and special tools should be used to dismantle static mating parts. It is not allowed to hammer or pry randomly

in addition, conditions should be created for assembly during disassembly. For non interchangeable parts, they should also be marked or placed in pairs during disassembly, so that they can be reset during assembly, which can ensure assembly accuracy and reduce unnecessary wear

b) mechanical assembly

the fitting accuracy and dimensional accuracy must be guaranteed during assembly. In order to ensure the fitting accuracy, the selection method, repair method and adjustment method can be used during assembly. Dimensional accuracy mainly refers to the error degree of the assembly dimension of each part in the assembly, that is, in the assembly, attention should be paid to eliminating the cumulative error to avoid the adverse impact on the machine due to the increase of the cumulative error

the seal in the assembly is also very important. In the printing press, the seal is mainly used for air pump, gearbox and other parts, and air leakage and oil leakage will occur when the seal fails. Therefore, the sealing materials selected in the repair should be appropriate, the assembly should be reasonable, and the liquid sealant should be selected for static sealing. According to the different nature of use, dry adhesive type, dry peelable type, non dry adhesive type and semi dry viscoelastic type should be used respectively

the preparations before assembly must not be ignored, including the inspection before assembly, the cleaning during assembly and the assembly of components. The last is the test run after assembly, which has two functions: one is to check the quality of assembly; The second is to adjust the machinery

c) cleaning of mechanical parts

cleaning of mechanical parts is an indispensable link in machine maintenance, and the cleaning content is mainly oil and rust removal

there are three main methods of degreasing and cleaning: alkali solution degreasing, organic solvent degreasing and metal cleaning. The alkaline solution mentioned here is mainly the alkaline solution with emulsifier added, which has a good effect on cleaning mineral oil. The so-called organic solvent generally refers to gasoline, kerosene, etc., which can dissolve all kinds of grease without damaging parts. In addition to gasoline and kerosene, alcohol, acetone, ether and other organic solvents can be selected for fine parts and bonding parts with high precision. Metal cleaning agent is a new type of synthetic detergent, which has a strong decontamination ability due to the wetting, penetration, emulsification, dispersion and other functions caused by the reduction of interfacial tension by base surfactants. Using this kind of cleaning agent is non-toxic, non corrosive, non combustible, non explosive, non polluting, and has certain rust prevention ability. The cost is also low, so it has been widely used

rust removal and cleaning methods mainly include mechanical method and chemical method. Mechanical derusting is generally carried out with wire brushes, scrapers, emery cloth, etc., and sometimes with electric grinding wheels and steel wheels. Mechanical rust removal is easy to leave scratches on the working surface, and it is only suitable for the surface rust removal of unimportant parts. Chemical derusting generally uses hydrochloric acid, sulfuric acid and phosphoric acid to remove alkaline metal oxides. The method is simple and derusting fully ensures the geometric accuracy of the whole machine. When using this method to remove rust, it is necessary to master the concentration ratio of solvent

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