Mechanical maintenance and repair inevitably require disassembly and installation of the machinery. The process and procedures of disassembling and assembling machinery are also related to the quality of mechanical maintenance and repair. Therefore, the disassembly and installation of machinery require attention to craftsmanship and procedures.
1, Simple mechanical disassembly
The mechanical disassembly methods are divided into: tapping, pulling, and pressing. In mechanical disassembly, different disassembly methods should be adopted according to the actual situation.
(1) Click to unload. Unloading is the most commonly used method in dismantling work. It uses the impact force of a hammer or other heavy object to disassemble parts. The advantage of disassembly is that it is easy to use tools, convenient to operate, and does not require special tools or equipment. Therefore, almost all parts can be disassembled by tapping. Its drawback is that if the disassembly method is improper, the parts are easily damaged or destroyed. Attention must be paid to safety when unloading.
In mechanical maintenance, due to the various types of disassembled parts and the fact that they are usually disassembled on site, hammers are commonly used for disassembly. Due to the characteristic of impact during disassembly, the following precautions must be taken:
1. Choose a hammer of appropriate size based on the size, weight, and firmness of the disassembled parts, and pay attention to the intensity of the force applied. Experience has shown that if the weight of the disassembled parts is large and the fit is tight, and the hammer chosen is too light, the parts are not easily moved, but on the contrary, they are prone to becoming rough.
2. Protective measures should be taken for the unloaded components. Usually, copper rods, rubberwood rods, wooden rods, wooden boards and other cushioning materials are used to protect the shaft end, sleeve end, wheel rim, etc. that are hit. The hammer should not be directly struck on the disassembled parts. In general, the hammer should be struck on the cushion.
3. First, conduct a trial run on the unloaded components. The purpose is to examine the firmness of the bonding of the parts, probe the direction of the parts, and if a solid sound is heard, immediately stop the disassembly and conduct an inspection to see if it is due to the opposite direction or missing fasteners. If so, the unloading method should be corrected. If severe rust is found on the parts, some kerosene can be added for lubrication.
4. Pay attention to safety. Before unloading, check if the hammer handle is loose to prevent the hammer from falling off the handle and flying out when struck hard. To observe whether there are people or other obstacles in the space traversed by the hammer, it is generally not advisable to directly support the cushion (pad iron) with hands, and it is best to clamp it with pliers.
(2) Pull and unload. Pulling and unloading is a static disassembly method, which has the advantage that the disassembled parts do not bear impact force, making disassembly safer and less likely to damage the parts. Its disadvantage is that it requires the production of specialized pulling tools.Pull off is suitable for disassembling parts with high precision that cannot be struck or parts that cannot be struck.
(3) Pressure relief. Unloading is a method of disassembling various hand presses or hydraulic presses, and is also a static disassembly method that is generally suitable for stationary fitting parts with simple shapes. In the disassembly of maintenance machinery, many parts cannot be disassembled on the press, so this method is less commonly used.
(4) Destructive disassembly. Destructive disassembly is the least commonly used method in maintenance disassembly, especially for certain economically valuable parts that are not suitable for use. Only when disassembling fixed connectors such as hot pressing, welding, riveting, or when the shaft and sleeve are interlocked, or when the spline is twisted, deformed, or severely corroded, can this measure of preserving the main component and damaging the secondary components be taken as a last resort. Destructive dismantling is generally carried out using methods such as turning, sawing, chiseling, and cutting.
(5) Inspection, marking, cleaning, and placement during dismantling work.
1.Inspection during disassembly. The disassembly process not only involves dismantling and disassembling the components, but also requires a comprehensive inspection and judgment of the components to conduct research for the next assembly process.
For example, when disassembling various bearings, carefully inspect the wear of steel balls, shaft bowls, and shaft stops. Because it is impossible to accurately determine the wear and tear of these parts before disassembly, if inspection is not carried out during disassembly and a problem is only discovered when reinstalling, it will waste time and affect maintenance work.
2.Mark the disassembly of components. Some parts need to be marked before disassembly to ensure smooth reassembly and quality assurance. The main components to be marked are: ① directional components. Like the central axis of a bicycle Some parts that cannot be interchanged for matching grinding and grinding, such as brake shoes for bicycle brake pads Some non-standard bolts and washers. The bolts and washers at a certain position on the bicycle chain box must be positioned and assembled.
3.Cleaning and bandaging. After mechanical disassembly, it is necessary to carefully clean and wipe, and some parts need to be coated with oil for rust prevention, and then wrapped with waste cloth or paper.
4.Placement of components.
(1) For bicycle wheels, forks, handlebars, frames, and other components, they should be properly padded and leveled after disassembly.
(2) After disassembling the parts on the shaft components, it is best to place them in the original order and direction, or connect them in series with thin iron wires, ropes, etc. This is very convenient for assembly.
(3) For small items such as the kilogram spring inside a bicycle flywheel, they should be immediately inserted back into the hole after disassembly, cleaning, and inspection.
2, Simple mechanical assembly
(1) Assembly work and its importance. Assembly refers to the process of connecting individual parts that have been repaired, processed, and inspected to form components and parts in various forms, and finally connecting them into a complete machine. These parts include the following three parts (taking a bicycle as an example):
1. Basic components - namely the main body parts, such as the frame, handlebars, flywheel, etc.
2. General components - front, middle, rear axles, chains, front and rear brake components, etc.
3. Standard parts - fasteners such as screws, nuts, washers, joints, pins, etc.
(2) Assembly is the final process in mechanical repair. Therefore, the assembly process is the key to ensuring that the machinery meets all technical requirements. For a bicycle: good assembly quality can improve mechanical efficiency and make riding light and agile. On the contrary, it cannot and may even result in the inability to ride. The following points are key to ensuring assembly quality:
When assembling rolling bearing components such as front axle, middle axle, rear axle, front fork, footrest, flywheel, etc., in addition to adding lubricant, the clearance must be carefully adjusted according to the assembly process. The requirement is to achieve the minimum gap, flexible rotation, and a clearance of no more than% #&millimeters.
2. Assemble the brake, requiring effective braking during braking; When not braking, there should be no resistance to rotation. Therefore, when assembling the brake, the position of the brake pad should be appropriate, the contact area should be large, there should be a gap of 2-4 millimeters, and it should be able to flexibly and automatically return to its original position after braking.
3. For the large gear plates, chains, flywheels, etc. used for transmission, if their mutual positions are not assembled correctly, such as if the chain assembly amplitude is too tight, it will cause the chain and teeth to not mesh well, resulting in premature wear or noise, and will also increase resistance.
4.When assembling sliding connection components, the tightness should be appropriate and lubricant should be added, otherwise it may damage the parts or cause "biting" phenomenon.
We are Ningbo Shenglu Bicycle Industry Co., Ltd., a professional supplier and manufacturer of bicycle accessories. The main products include five series: bicycle axle pads, flywheels, brakes, bowl sets, and central axles. Our products are exported to more than 100 countries and regions around the world, and we are one of the globally renowned brands. Especially popular in European and American countries. Welcome buyers with needs to contact our online customer service or send an email for consultation. website: https://www.hubs-sf.com
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