Mechanical repair personnel are required to face the problems of disassembly and assembly when repairing the printing machinery. In particular, assembly will directly affect the mechanical properties, and the assembly quality is not high, causing serious mechanical wear.
a) Mechanical disassembly
Due to the large number of types of printing machinery and the different shapes of parts, it is difficult to describe them one by one. Here is a general disassembly principle.
First of all, before disassembling, you must understand the structure, function, and principle of the machine. Check the relevant technical data and instructions first. From the actual point of view, to determine the demolition part, the part that can not be removed should not be removed as much as possible, but for the part that is not dismantled, it must undergo an overall inspection to ensure quality.
Secondly, in the disassembly process, disassembly shall be performed from the inside to the outside of the watch, and the external accessories, tubing, etc. shall be disassembled first, and then disassembled according to the order of the parts after the first assembly. Marks shall be made for the disassembly of the more important parts. List the numbers and avoid clutter. It is also important to use tools properly when disassembling. The tools must be compatible with the parts being disassembled. If you want to remove the threaded connector to use the appropriate wrench, remove the static fittings to use special tools, can not smash hammer, chaos and so on.
In addition, when disassembling, conditions should be created for assembly. For non-interchangeable parts, they should also be marked or placed in pairs when they are removed so that they can be reset during assembly. This will ensure assembly accuracy and reduce unnecessary wear.
b) Mechanical assembly
When assembling, it is necessary to ensure the matching precision and dimensional accuracy. To ensure the matching accuracy, the matching method, repair method, and adjustment method can be used during assembly. The dimensional accuracy mainly refers to the degree of error in the assembly dimensions of each part of the assembly. That is to say, in the assembly, it is necessary to pay attention to eliminate accumulated errors and avoid adverse effects on the machine due to the increase of accumulated errors.
The seal in the assembly is also very important. In the printing press, the seal is mainly used in the air pump, gear box and other parts. When the seal fails, air leakage and oil leakage will occur. Therefore, the sealing material used in the repair should be appropriate, and the assembly should be reasonable. The liquid sealant should be used for static sealing. According to the different nature of use, dry adhesion, dry stripping, and non-drying adhesion And semi-dry viscoelastic type and other varieties.
The preparatory work before assembly must not be overlooked. Its contents include pre-assembly inspection, assembly cleaning and assembly of components. The final step is the commissioning after assembly. The second and the first function is to check the quality of the assembly. The second is to adjust the machine.
c) Cleaning of mechanical parts
The cleaning of mechanical parts is a necessary part in mechanical repair. The cleaning content is mainly degreasing and rust removal.
The methods of degreasing and cleaning mainly include alkali solution deoiling method, organic solvent deoiling method and metal cleaning degreasing method. The alkali solution mentioned here is mainly an alkali solution added with an emulsifier, and it has a good effect on the cleaning of mineral oils and fats. The so-called organic solvents generally refer to gasoline, kerosene, etc. It can dissolve various oils without damaging parts. In addition to gasoline and kerosene, alcohol, acetone, and ether can be used for small parts and adhesive parts with high precision, respectively. And other organic solvents.
Metal cleaning is a new kind of synthetic detergent. Because the surface active material reduces the interfacial tension, it produces various functions such as wetting, penetration, emulsification, and dispersion, which makes it have strong decontamination ability. The use of this cleaning agent is non-toxic, non-corrosive, non-flammable, non-explosive, and non-hazardous. It also has certain rust-preventing ability and low cost, and it has been widely used.
Rust cleaning methods mainly include mechanical and chemical methods. Mechanical derusting is generally performed with wire brushes, doctor blades, emery cloth, etc., and sometimes it can also be performed with electric grinding wheels and wire wheels. Mechanical rust removal can leave scratches on the work surface and should only be used for surface rust removal of non-essential parts. Chemical rust removal generally uses hydrochloric acid, sulfuric acid and phosphoric acid to remove basic metal oxides. The method is simple and the rust removal effect is good. When using this method to remove rust, it is necessary to master the solvent concentration ratio.
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