Washing and cleaning parts. Parts cleaning

Washing and cleaning parts

After disassembly of machines and units, the parts are subjected to cleaning, degreasing and washing. Cleaning and washing parts has a big impact on quality overhaul. Complete removal of all contaminants improves the quality of troubleshooting, increases the service life of parts, and reduces the appearance of defects. The rational choice of the method of washing and cleaning depends on the type of pollution, size, configuration of parts and places of deposits of pollution, economic considerations, but the main factor determining the choice of method is the type of pollution.

Pollution of road machines working in difficult road construction conditions can be divided into the following types: deposits of non-fatty origin (dust, dirt, etc.) and oily mud; lubricant residues; carbon deposits; scale; corrosion; technological deposits in the process of repair; deposits of cement mortar and concrete.

Rice. 12. Schemes for hanging a mechanized tool:
a - on a cable with a counterweight; b - on a spring suspension;
1 - counterweight; 2 - wrench; 3 - block; 4 - cable; 5 - lever; b - emphasis; 7 - switch

Deposits of non-fat origin and oily mud are formed on the outer surface of machine parts and assemblies. Dust, dirt during the operation of machines fall on dry and oily surfaces. Such contaminants are relatively easy to remove.

Lubricant residues are found on all parts of machines that operate in an oily environment; this is the most common type of pollution, the removal of which requires special preparations and cleaning and washing conditions.

Carbon deposits are products of thermal oxidation of lubricants and fuels. They are formed on the parts of internal combustion engines and, depending on the degree of oxidation, are divided into soot, varnish films, precipitation and asphalt-resinous substances, in addition, carbon deposits include bitumen and asphalt concrete mixture residues that remain on the outer surfaces of road machine parts during operation. them with these materials.

Carbon deposits are formed during the combustion of fuels and oils. The unburned solid particles released adhere to the oil films and gradually sinter, forming a layer of soot on the walls of the combustion chambers, piston crowns, valves, candles and exhaust manifolds.

Lacquer films are formed when high temperatures are applied to oil layers of small thickness. They deposit on connecting rods, pistons, crankshafts and other parts.

Sediments formed from the products of oil oxidation, fuel, dust and other particles are a greasy, sticky mass that settles in the oil pan, oil channels, and in the oil filter.

Asphalt-resinous substances are formed under the influence of high temperatures and atmospheric oxygen. Most of these substances are solid particles that are part of the sediment and can have an abrasive effect on parts. To remove carbon deposits, special preparations and certain conditions are required.

Scale is deposited on the internal surfaces of parts of the engine cooling system and is formed as a result of the release of calcium and magnesium salts when water is heated to a temperature of 70-85 ° C. The thermal conductivity of scale is many times lower than the thermal conductivity of metal, so even a minimal layer of scale significantly worsens the conditions for heat transfer, leads to overheating of engine parts, especially parts of the connecting rod and piston group and cylinders. As a result, the engine power decreases, the consumption of fuel and lubricants increases, and the wear rate of parts increases. Descaling is a relatively complex and time-consuming process.

Corrosion - iron oxide hydrate is formed as a result of chemical and electrochemical destruction of the surfaces of parts of the engine cooling system and all other metal surfaces.

Technological pollution on details and knots are formed in the course of repair, assembly and running-in of units. These are the remains of lapping pastes, grinding wheels, metal chips, etc. They also need to be removed in a timely and thorough manner, as they can cause intense wear of the rubbing surfaces of parts.

Deposits of cement mortar and concrete occur on the parts during the operation of the machine with these materials and as a result of unsatisfactory Maintenance machines. Removing these deposits is a simple but time consuming process.

Methods for removing contaminants. In the repair industry, the most widespread are the physicochemical, ultrasonic and mechanical methods of washing and cleaning parts.

The physico-chemical method of washing and cleaning (jet and in baths) is that contaminants are removed from the surfaces of parts with aqueous solutions of various preparations or special solvents under certain conditions. The main modes of high-quality washing and cleaning with aqueous solutions are: high temperature of the washing chemical solution (80-95 ° C), flow or jet of the solution at significant pressure and effective detergents.

The ultrasonic washing and cleaning method is based on the transfer of energy from an ultrasound emitter through a liquid medium to the surface to be cleaned.

Oscillations of 20-30 kHz cause large accelerations and lead to the appearance of small bubbles in the liquid medium, upon rupture of which hydraulic shocks occur. great strength, destroying carbon deposits on the surfaces of parts within 2-4 minutes, and oil films within 30-40 seconds. On fig. 13 shows an ultrasonic washing and parts cleaning unit. The PMS-4 transducer is attached to the bottom of the welded metal pool (Fig. 13, b) and receives power from the ultrasonic generator UZG-2.5. During operation, the converter (Fig. 13, a) is cooled by running water, which is supplied through the pipeline and drained through the pipeline. The terminal block is used to connect the converter to the generator. When using an aggressive cleaning solution, a vinyl plastic tank is installed in a metal bath, The space between them is filled with water. The parts to be cleaned are hung in the bath in a slatted basket with meshes of at least 3X3 mm. The ultrasonic method is used mainly for cleaning small parts of complex configuration (parts of carburetors, fuel pumps, electrical equipment, etc.). For ultrasonic degreasing of parts, a solution of the following composition can be recommended: soda ash -30 g/l; trisodium phosphate -30, emulsifier OP-10-5-10 g/l.

Rice. 13. Installation for ultrasonic washing and parts cleaning:
a - converter (emitter); b - ultrasonic unit

The temperature of the solution should be 50-55 °C. The use of ultrasonic washing and cleaning of parts (especially small ones) gives a significant economic effect by speeding up the cleaning process and improving the quality of machine repair as a whole.

The essence of the mechanical method is to manually clean the surface of the part with scrapers, brushes or mechanized stone chips, abrasive and other materials supplied together with air, water or a cleaning solution.

Washing liquids and preparations. As washing liquids, aqueous solutions of caustic soda (caustic soda), soda ash (sodium carbonate) with the addition of emulsifiers (liquid glass, laundry soap, trisodium phosphate) and anti-corrosion additives (chromic, sodium nitrite) and Traktorin, ML- 51, ML-52, "Labamid-101", "Labamid-203", AM-15, MS-6, MS-8, etc.

Aqueous alkaline solutions are heated to a temperature of 80-95 °C. When the heating temperature drops to 70 °C and below, the viscosity of oil deposits remains elevated, which makes it difficult to separate them and impairs the quality of washing. Due to the strong corrosive effect, alkaline solutions (with the presence of caustic soda) intended for washing parts made of ferrous metals cannot be used for parts made of aluminum alloys. After washing with alkaline solutions, the parts should be rinsed with clean water.

Synthetic preparations Traktorin, ML-51, ML-52, MS-6 and MS-8 are the most effective detergents produced by chemical industry. The use of these preparations is economically advantageous in comparison with expensive caustic soda. Their main advantages over aqueous alkaline solutions are low toxicity, good solubility in water, and the possibility of being used for parts made of ferrous and non-ferrous metals. In addition, after using these preparations, there is no need to rinse the parts with water.

Preparations "Traktorin", ML-51 and MS-6 are used in machines and installations for jet washing of parts. The preparation ML-52 and MS-8 is used for boiling out parts in baths from strong carbon deposits. The temperature of solutions from these preparations is 70-80 °C. Duration of degreasing 8-20 min. The concentration of the aqueous solution is 20-30 g/l.

The AM-15 preparation, which is a solution of surfactants in organic solvents (xylene, olizarin oil and ethoxylated alcohol), is used to clean parts from strong tar deposits in baths, as well as to restore the throughput of coarse filters.

Preparations "Labamid-101" and "Labamid-203" are designed to remove oil and carbon deposits of various parts. "Labamid-101" is used in the form of aqueous solutions with a concentration of "Labamid-203" is used in the form of aqueous solutions with a concentration of 25-35 g / l at a temperature of 80-100 ° C in bath-type washing machines.

Rice. 14. Single chamber conveyor parts degreasing machine:
1 - pumping pumping unit; 2 - drain manifold; 3 - injection pumping unit; 4- washing chamber; 5 - settling tanks; 6 - plate conveyor

Equipment. The choice of equipment depends on the type of contamination of the parts, their size, detergents and the capacity of the repair company. For washing, degreasing and cleaning parts in the repair industry, the most widely used are conveyor-type jet washers, intermittent chamber washers, bathtubs and special installations (for cleaning parts from carbon deposits, scale, etc.).

Conveyor-type jet washers designed for washing units, assemblies and parts can be one-, two- and three-chamber. Single-chamber machines are intended for washing with water or degreasing with solutions that do not require subsequent rinsing with water. On fig. 14 shows a single-chamber conveyor jet washing machine designed for degreasing parts using non-aggressive solutions (Traktorin, ML-51, MS-6), eliminating the need for subsequent rinsing of parts. The washing device for this machine is made in the form of a pumping hydrant. The movement of parts is carried out by a plate-type conveyor. The speed of the conveyor belt is 0.1-0.6 m/min. The washing solution in this machine is heated with steam to a temperature of 75-85 °C. Large parts are placed directly on the conveyor plates, while small parts are fed into the washer in mesh baskets.

Two-chamber machines are used for washing parts and assemblies with alkaline solutions in the first of the chambers, followed by hot water washing in the second.

Three-chamber machines have three washing zones. In the first zone, dirt is softened with a washing solution, in the second zone it is thoroughly washed and in the third zone it is rinsed with hot water. . It is economically feasible to use conveyor-type machines at large repair enterprises.

In intermittent chamber washing machines, parts are washed with a single solution, followed by rinsing with hot water. In the latter case, there are two baths: for washing solution and hot water. These machines are used in small repair enterprises and repair shops of operating farms.

Bathtubs are the simplest washing installations. Most often they are used for digestion of parts in alkaline or acid solutions. Bathtubs are made of steel; they consist of two compartments, one for washing solution, the other for water. The top of the bath is closed with a double-leaf lid.

Cleaning parts from soot. Details of soot can be cleaned by mechanical and physico-chemical methods.

Removal of carbon deposits mechanically can be carried out using metal brushes and scrapers, stone chips, hydro-sandblasting. When applying brushes to scrapers, it is not always possible to completely remove carbon deposits from surfaces located in hard-to-reach places of the part. In addition, after the removal of soot on the smooth surfaces of the parts, risks are formed, which during operation serve as foci of soot formation. Cleaning parts from carbon deposits with metal brushes and scrapers, due to its simplicity, has become widespread in the repair shops of road construction organizations. At large repair enterprises, cleaning of parts from soot with stone chips (crushed cherry and apricot pits) is widely used. This method is used to clean pistons, block heads, exhaust manifolds from carbon deposits. Its essence lies in the fact that crushed shells of fruit pits are fed to the part under air pressure of 0.4-0.5 MPa (4-5 kgf / cm2). Hitting the surface of the part, it cleans the deposit. On fig. 15 shows the design of the installation for cleaning parts with stone chips. Dry stone chips are poured into the tank through the door. Then it enters the bunker through the grid and the valve, and from there - into the mixer. The valve is opened at the right time with a lever. Air is supplied through the tube to the mixer, which carries the crumb into the sleeves to the tips. The amount of air entering the mixer is regulated by a valve, which is actuated by a pedal. The parts to be cleaned are placed on a rotating table. The worker, through the holes in the front door, inserts his hand into the protective sleeve and, taking the tip, directs a jet of stone chips onto the part, observing the cleaning process through the viewing glass.

Rice. 15. Installation for cleaning parts with stone chips

The working chamber is illuminated by a lamp. Dust crumbs and soot particles are sucked out through the pipe using a fan. If the valve is clogged with crumbs, then it is cleaned with compressed air supplied to it through the pipe when the tap is opened. This method economical, efficient and high quality. For example, to clean a set of parts of one D-54A engine from carbon deposits, 4-5 kg ​​of stone chips are consumed, which is 15-20 kopecks in monetary terms, the cleaning time is 30 minutes. Due to the fact that the crumb is deformed upon impact, there are no burrs and scratches on the cleaned surface of the part.

Small parts (valves, tappets, springs, etc.) are economically expedient to be chemically cleaned of carbon deposits. In this case, the parts are loaded into a bath with an alkaline solution, which consists of caustic and soda ash, liquid glass, laundry soap and water. The parts are kept in this solution for 3-4 hours at a temperature of 90-95 ° C and, after softening, the carbon deposits are removed with hair brushes or rags. After cleaning, the parts are washed in cold and hot water.

Rice. 16. Descaling unit:
1 - bath; 2 - cover; 3 - roller table; 4 - electric motor; 5 - special pump; 6 - electric heating device

Cleaning parts from scale. Cleaning of the water jacket of blocks and cylinder heads of engines is carried out at special installations. On fig. 16 shows an installation for descaling the block's water jacket. The block is installed on roller table 3 and with the help of a hose attached to the side flange of the block, a solution of trisodium phosphate heated to 60-80 ° C is pumped through its jacket at the rate of approximately 3-5 kg ​​per 1 m3 of water. Can be used for descaling and 8-10% solution of hydrochloric acid. To protect the internal surfaces of parts from corrosion, 3-4 g of urotropine per 1 liter is added to the solution as an inhibitor. The solution is heated to 50-60 °C. The duration of washing, depending on the thickness of the scale layer, can be in the range of 10-70 minutes. After removing scale, the internal cavities of the parts must be rinsed with clean water.

TO Category: - Repair of road machines

TO Category:

Repair industrial equipment

Cleaning, washing and troubleshooting parts

Cleaning and rinsing of parts

After disassembling the machine, parts and assembly units must be cleaned and washed, since the cleaner the parts, the easier it is to identify defects in them. In addition, cleaning and rinsing contaminated parts improves repair sanitation.

Cleaning and rinsing should also be carried out when preparing parts for restoration or painting.

The parts of the repaired equipment are cleaned by the following methods: thermal (fire), mechanical, abrasive, chemical.

The thermal method consists in cleaning parts (removing rust and old paint) with a flame (blowtorch or gas burner).

With a mechanical cleaning method, old paint, rust and hardened oil deposits are removed from parts with brushes, mechanized cutters, various manual machines and other portable mechanisms.

With the abrasive method, cleaning is carried out mainly by hydrosandblasting installations.

With the chemical method, old paint, grease, oil deposits and other contaminants are removed with a special paste or solutions consisting of quicklime, chalk, caustic soda, fuel oil and other components.

Rice. 1. Stationary washing machine

Mechanized washing of parts is carried out in stationary and mobile washing installations under the action of strong jets resulting from the supply of liquid by a pump under a certain pressure.

On fig. 1 shows a stationary washing machine, consisting of a washing chamber, above which eight tanks with washing liquid with a volume of m3 each are placed. Seven tanks with pyramidal bottoms located on two sides of the installation, in addition to their main purpose, are also settling tanks. A solution of the following composition is used as a washing liquid: 2-3% soda ash; 0.3-0.5% detergent OP-7; 2-3% sodium nitrite; the rest is water.

From the tanks, washing liquid at a temperature of 80 ° C is pumped under a pressure of 0.6 MPa (6 kgf / cm2) into a pumping hydrant (pipe with 40 nozzles).

The liquid is heated by steam through tubular heaters mounted inside the tanks. The used solution flows into the pan with a grid, from where it is again supplied by a special pump to the tanks.

A closed monorail with eleven hangers passes through the washing chamber, which move with the help of a drive station (not shown in the figure) at a speed of 0.2 m/min.

Rice. 2. Mobile washing machine

Special baskets with loaded parts and assembly units are hung on suspension hooks using a cantilever beam and an electric hoist. Assembly units and parts are fed into the washing chamber through self-opening and closing multi-leaf doors.

Once a quarter, it is supposed to drain all the washing liquid through the dirt collector, rinse the tanks and fill in a new solution.

To wash parts directly at the workplace, mobile washing baths or washing machines are used; kerosene is used as a washing liquid. In baths, parts are washed manually, and in washing machines this process is mechanized.

On fig. 2 shows a mobile washing machine, consisting of a trolley with a fixed bathtub, in the lower part of which a mesh is installed.

For washing small parts, a shelf is attached to the side wall of the bath. The bath is closed with a lid.

A branch pipe is welded to the inclined planes of the bottom of the bath, through which the contaminated liquid is drained into a tank, which has partitions that form settling tanks in the tank. An electric pump is mounted in the tank, which pumps liquid through a pipe and a gasoline-resistant hose to flush parts.

Troubleshooting parts

After washing, scratches, cracks, dents are clearly visible on the surfaces of the disassembled parts, and it is possible to measure the parts with the necessary accuracy during troubleshooting.

Troubleshooting of washed and dried parts is carried out after they are assembled according to assembly units, which must be done carefully and carefully. Each part is first examined, then its shape and dimensions are checked with an appropriate calibration and measuring tool. In some cases, the interaction of this part with others associated with it is checked to determine whether it is possible to repair this part or it is more expedient to replace it with a new one.

Information about the parts to be repaired and replaced is entered in the list of defects for equipment repair.

A properly drawn up and sufficiently detailed list of defects is an essential factor in preparing for repairs. This responsible document is usually compiled by an equipment repair technologist with the participation of a foreman of the repair team, a foreman repair shop, representatives of OTK .

In case of flaw detection it is important to know and be able to set the limits of wear for various parts of the equipment and the allowable limit repair dimensions. For example, it is allowed to reduce the thread diameter of lead screws - 8% of the nominal diameter; reduction in the diameters of shaft necks, spindles and axles - 5-10% of the nominal diameter; reduction of the wall thickness of hollow spindles and axes - 3-5% of the nominal thickness.

Parts are sorted into three groups: the first - suitable for further operation; the second - requiring repair or restoration; the third - unusable, to be replaced.

Repair is subjected to labor-intensive parts, the restoration of which is much cheaper than newly manufactured ones. The repaired part must have a significant margin of safety, allowing to restore or change the dimensions of the mating surfaces (according to the system of repair dimensions), without reducing (in some cases increasing) their durability, while maintaining or improving the performance of the assembly unit and unit.

Parts must be replaced if the reduction in their size due to wear interferes with the normal operation of the mechanism or causes further intensive wear, which leads to the failure of the mechanism.

When repairing equipment, parts with wear limit are replaced, as well as parts with wear less than permissible if, according to calculations, they do not last until the next repair. The service life of parts is calculated taking into account the wear limit and the intensity of their wear under actual operating conditions.

When troubleshooting, parts must be marked with the serial number of the list of defects, as well as the inventory number of the machine or machine, this facilitates further repair operations.

Marking is carried out with stamps, paint, tags, electrograph or acid. Branding stuffs designations on non-working surfaces of non-hardened parts. In other ways, both hardened and non-hardened parts are marked. For example, when marking non-hardened parts, a rubber stamp is wetted in a solution of 40% nitric acid, 20% acetic acid and 40% water; when marking hardened parts - in a solution of 10% nitric acid, 30% acetic acid, 5% alcohol and 55% water (for hardened parts); the wetted stamp is applied to the non-working area of ​​the part to be marked. After exposure for 1-2 minutes, the surface is neutralized by wiping with a swab dipped in a solution of soda ash.

Parts that are decided to be replaced during troubleshooting are stored until the repair of the mechanism is completed, they may be needed to draw up drawings or make samples of new parts.

Washing the parts before the start of the repair of the car contributes to the high quality of its repair. When repairing, for example, a car engine, manual washing and automatic washing are used. Hand washing is usually done at small repair shops. Using a manual sink, the part or assembly is installed on a special pallet. A sink is created with a detergent and a brush. Gasoline, kerosene or soda solution is used as a detergent.

Gasoline is a less successful cleaning fluid. Its disadvantage is the highest vapor volatility. And this is related to its toxicity. Gasoline is especially unsafe when working indoors. Gasoline vapors in general aggravate environment. Gasoline does not completely wash off small particles of dirt or abrasive dust after repairing parts. Gasoline renders negative impact on cuffs and seals of parts and assemblies, which are made of rubber. The only advantage of gasoline is that oil pollution quickly dissolves in it. After degreasing parts with gasoline, from time to time you can find any flaws on their surface.

Vapors of kerosene, unlike gasoline vapors, are actually not volatile. The washing characteristics of kerosene are significantly worse than those of gasoline. After washing in kerosene, the parts remain oily. By this they are quite "attract" dust particles. Therefore, kerosene during repairs can only be used as an auxiliary substance.

Soda solution differs from gasoline and kerosene in that it is non-toxic and completely harmless. True, it has an irritating effect on the skin of the hands. Its disadvantage is that it is effective only when heated. If the details of a complex configuration and at the same time are very dirty, then the soda solution will be difficult to wash off. And in duralumin parts, it causes corrosion. In small workshops it is used occasionally. He asks for heating and frequent changes of solution.

Other detergents are also used. In large repair shops, manual washing is not used so extensively due to low productivity. For this reason, washing installations are used at medium and large repair enterprises. These installations provide washing of parts with heating and the upcoming cleaning of the dirty solution. Installations own highest efficiency. But manual washing cannot be completely excluded from the repair process, since very dirty parts are still subjected to preparatory cleaning by hand.

Washing is a series of operations that are performed in the following sequence:

1) the external surfaces of the parts are cleaned from dirt;

2) clean the internal cavities and channels of parts from carbon deposits and wear particles;

3) the surfaces of the sealing parts are washed;

4) wash the parts themselves;

5) purge the internal channels and dry the parts.

At different washing steps, also depending on the contamination of the parts, different detergents are used. If the engine is very dirty on the outside, then mechanical cleaning of the surface is usually done first with steel brushes. Such brushes are also used for preparatory cleaning of the internal channels of parts from carbon deposits. Cleaning is done very carefully so as not to throw the deepest scratches on the surface.

It happens that after washing the parts, it is necessary to re-do mechanical cleaning. In order to soften the dirt, they are usually dipped in a washing solution beforehand. It happens that blowing out the internal channels is enough to clean dirt and chips. Compressed air is used for blowing. Increased attention should be paid to the intake manifold of the motor, which is damaged. It is not necessary to wash parts that have closed rolling bearings. Together with the detergent, dirt can get into such bearings. The detergent can completely wash away the grease. And this leads to a quick failure of the bearings.

Very dirty external surfaces of such units must be wiped with a rag, which is slightly moistened with washing liquid. Despite the importance of the process of washing parts, in practice, washing is often neglected. Car parts are sometimes not washed at all, and if they are, then somehow. This happens due to a complete misunderstanding of the processes that occur in the car. And the consequences of such a misunderstanding can be quite severe. In our article "Washing and cleaning of car parts" we tried to explain to you the full significance of this process.

After disassembling the machine, the assembly units and individual parts must be cleaned and washed from dirt, chips, foreign particles, soot, grease, coolant in order to identify defects, improve sanitary repair conditions, and also to prepare parts for restoration and painting operations.

Parts cleaning methods:

Mechanical. Rust, old paint, hardened lubricant, soot, etc. are removed from parts with manual or mechanized brushes, cutters, scrapers, scrapers, and various machines.

Abrasive. Cleaning is carried out using sandblasting or hydrosandblasting of the part.

Thermal. Old paint, rust is removed by heating the surface of the part with the flame of a blowtorch or gas burner.

Chemical. Remains of lubricant, coolant, old paint are removed with special pastes and washing solutions, which include caustic soda, quicklime, chalk, fuel oil, etc.

Parts are washed with aqueous alkaline solutions and organic solvents. First in a hot solution, then in clean hot water. After that, the part is thoroughly dried with compressed air and napkins. In alkaline solutions, parts with elements made of non-ferrous metals, plastics, rubber, fabrics are not washed. Parts with polished and ground surfaces should be washed separately.

Parts washing methods:

1. Manual. Washing is carried out in two baths filled with an organic solvent (kerosene, gasoline, diesel fuel, chlorinated hydrocarbons).

2. In tanks by immersion. Washing is carried out in a stationary or mobile tank with a grid on which the parts are laid, and a tube with an electric spiral or a coil for heating the washing solution to a temperature of 80-90 ° C.

3. In washing machines. Stationary or mobile machines of various designs.

4. Ultrasonic. Rinsing is carried out in a special bath with heated washing liquid (alkaline solutions or organic solvents). A source of ultrasonic vibrations is placed in the bath, which creates high-frequency elastic waves that accelerate the separation of contaminants from the surface of the part.

Parts detection

Cleaned parts are subjected to flaw detection in order to evaluate their technical condition, identifying defects and determining the possibility of further use, the need for repair or replacement. During fault detection, the following are revealed: wear of working surfaces in the form of changes in the dimensions and geometric shape of the part; the presence of crumbling, cracks, chips, holes, scratches, scratches, scuffs, etc .; residual deformations in the form of bending, twisting, warping; change in physical and mechanical properties as a result of exposure to heat or the environment.

The detection of washed and dried parts is carried out after they are assembled according to the nodes, which must be done carefully and carefully. Each part is first inspected, then its dimensions are checked with an appropriate checking and measuring tool. In some cases, the interaction of this part with others associated with it is checked.

Methods for detecting defects:

1. External examination. Allows you to identify a significant part of the defects: holes, dents, obvious cracks, chips, chipping in bearings and gears, corrosion, etc.

2. Check by touch. The wear and tear of threads on parts, the ease of rotation of rolling bearings and shaft journals in plain bearings, the ease of movement of gears along the splines of the shaft, the presence and relative size of gaps in mating parts, the density of fixed joints, etc. are determined.

3. Tapping. The part is lightly tapped with a soft hammer or hammer handle to detect cracks, the presence of which is indicated by a rattling sound.

4. Kerosene test. It is carried out in order to detect a crack and its ends. The item is either immersed in kerosene for 15-20 minutes, or the alleged defective place is lubricated with kerosene. Then carefully wipe and cover with chalk. Kerosene protruding from the crack will moisten the chalk and clearly show the boundaries of the crack.

5. Measurement. With the help of measuring tools and means, the amount of wear and gap in the mating parts, the deviation from the specified size, the errors in the shape and position of the surfaces are determined.

6. Hardness test. Based on the results of measuring the surface hardness of the part, changes that have occurred in the material of the part during its operation are detected.

7. Hydraulic (pneumatic) test. Used to detect cracks and cavities in body parts. For this purpose, all openings in the body are muffled, except for one, through which fluid is injected under a pressure of 0.2-0.3 MPa. Leaking or fogging of the walls will indicate the presence of a crack. It is also possible to inject air into the housing immersed in water. The presence of air bubbles will indicate an existing leak.

8. Magnetic way. It is based on a change in the magnitude and direction of the magnetic flux passing through the part in places with defects. This change is recorded by applying dry or suspended in kerosene (transformer oil) ferromagnetic powder to the tested part: the powder settles along the edges of the crack. The method is used to detect hidden cracks and cavities in steel and cast iron parts. Stationary and portable (for large parts) magnetic flaw detectors are used.

9. Ultrasonic method. It is based on the property of ultrasonic waves to be reflected from the boundary of two media (metal and void in the form of a crack, shell, lack of penetration).

10. Luminescent method. It is based on the property of some substances to glow in ultraviolet rays. A fluorescent solution is applied to the surface of the part with a brush or by immersion in a bath.

The list of defects lists in detail the defects of the machine as a whole, each node separately and each part to be restored and hardened. A correctly compiled and sufficiently detailed list of defects is an essential addition to the technological repair processes. Therefore, this very responsible white paper usually draws up a technology for the repair of equipment with the participation of the foreman of the repair team, the foreman of the repair shop, representatives of the Quality Control Department and the customer shop.

Detection of washed and dried parts is carried out after they are assembled by units. This operation requires a lot of attention. Each part is first inspected, then its dimensions are checked with an appropriate calibration and measuring tool. In some cases, the interaction of this part with others associated with it is checked.

The list of defects lists in detail the defects of the equipment as a whole, each unit separately and each part to be restored and hardened.

When disassembling the equipment to be repaired into components and parts, the control and sorting of the ero parts into the following groups is carried out: 1) suitable for further operation; 2) requiring repair or restoration; 3) unusable, subject to replacement.

Similar information.

During the operation of machines, contaminants are deposited on the outer and inner surfaces of parts, differing in composition, properties, adhesion strength to the surface of parts. Pollution reduces the stability of protective coatings, increases the rate of corrosion processes, and reduces the level of maintenance and repair culture. Poor cleaning work during repairs reduces the post-repair resource by 20-30%. The complete removal of all contaminants greatly improves the quality of defect detection and restoration of parts, and makes it possible to increase labor productivity in disassembly and assembly work by 15-20%.

For the complete removal of contaminants at repair enterprises, multi-stage cleaning of parts is used. Cleaning works, except for the external washing of the machine upon receipt for repair, include cleaning of the dismantled machine and assembly units, cleaning of parts before flaw detection, cleaning of parts before assembling units, washing before painting. The choice of cleaning method largely depends on the nature of the contaminants, their places of deposition, the size and shape of the parts. The main factor determining the choice of cleaning method is the type of pollution.

Repaired machines may have the following types of pollution:

• deposits of non-fatty origin (dust, dirt, plant residues), residues of pesticides and oily-mud deposits
• lubricant residues
• carbon deposits (soot, varnish films, sediments, asphalt-resinous substances)
• scale
• corrosion products, paint residues
• technological pollution that appears during repair, assembly and running-in (metal shavings, lapping paste residues, wear products of grinding wheels, etc.)

The following cleaning methods are most widely used in the repair of machines:

• mechanical
• physical and chemical
• thermal

At specialized repair enterprises, in addition, electrochemical, ultrasonic and thermochemical methods are used.

Detergents

Deposits on the external surfaces of non-greasy origin are usually removed with a stream of water heated to a temperature of 70-80 ° C. To remove residual lubricants, a 1-2% solution of caustic soda is used. However, it is ineffective, and an increase in concentration of more than 6% causes corrosion of metals. In addition, caustic soda solution has a harmful effect on human skin.

In recent years, synthetic detergents (CMC) such as MS, Labomid, Temp, etc. have been used to clean surfaces. Detergents are mixtures of alkali salts and surface-active substances (surfactants). They are non-toxic, non-flammable and explosion-proof. They can be used to clean parts made of ferrous and non-ferrous metals. Surfactants are organic compounds that ensure the destruction of fatty films, prevent the re-deposition of contaminants, create stable emulsions when in contact with the aqueous component of the cleaning solution. These substances speed up the cleaning process. Detergents MS-6, MS-16, MS-18 are mainly used to remove oil-mud, resinous deposits in machines with jet and circulation cleaning of assembly units and machine parts. The concentration of solutions - 15-25 g/l at a temperature of 75-85°C, MS-8 and MS-15 - with jet and submersible cleaning from strong carbon deposits. Solution concentration - 20-25 g/l, temperature 80-100°C.

Synthetic detergents "Labomid-101" and "Labomid-102" are used to remove oil-mud and asphalt-tar deposits during blast cleaning. The concentration of solutions is 10-15 g/l at a temperature of 70-85°C. Labomid-203, similarly to the MS-8 preparation, is used to remove light asphalt-resin deposits during submersible cleaning, as it is characterized by increased foaming. Solution concentration - 20-30 g/l, temperature 80-100°C. "Labomid-315" is used for cleaning from strong asphalt-resinous deposits in baths without heating (15-20 * C) and without mechanical action.

Preparations "Temp-100" and "Temp-YuOA" are mixtures of alkali salts, surfactants and passivators. They are used for jet cleaning of parts and assembly units from oil and mud deposits and protection of the cleaned surface from corrosion (passivation). Solution concentration - 10-15 g/l, temperature 80-95 "C.

Detergents "Complex" and DIAS are designed for jet and steam jet cleaning of machines from pesticides. The concentration of solutions is 5-6 g/l, the temperature is 80-90°C (with steam jet 95-100°C).

Organic preparations AM-15 and "Rhythm" are designed to clean engine parts from strong resinous deposits by immersion in baths.

The AM preparation is a solution of surfactants in organic solvents. It is toxic, flammable and explosive. Its temperature should not exceed 40 "C. The drug "Rhythm" is made on the basis of chlorinated hydrocarbons.

Organic solvents (gasoline, kerosene, acetone, alcohols, etc.), mixtures of organic solvents and acid solutions - aqueous solutions of inorganic and organic acids are used to clean parts.

Cleaning of parts from soot, scale can be carried out in molten salts and alkalis in a bath at a temperature of 400-450 ° C.

Parts cleaning equipment

In the CRM farms, in regional workshops general purpose for cleaning assembly units and parts, mainly single-chamber jet washing machines OM-1366G-01, OM-837G, OM-4610-01, etc. are used. They are approximately the same in their design, they consist of a washing chamber, a sliding table (loading cart) for placing cleaned assembly units and parts with a total weight of 0.6 to 1.5 tons and baths for cleaning solution. Washing chambers are equipped with a movable shower device or a rotating loading table. The washing solution is heated to a temperature of 75-85 "With an electric or fire device. The pressure of the jet in shower devices in the range of 0.4-0.5 MPa is created by a centrifugal pump.

For cleaning parts and small-sized assembly units at engine repair sites, maintenance of machines in the CRM, submersible washing machines ORG-4990B, OM-9Yu1 or OM-281-OI are used. Productivity of the machine ORG-4990B - 0.4 t/h; the volume of the washing solution is 0.1 m3. The machine is equipped with a turbulator to create a flooded solution flow, which speeds up the process of cleaning parts.

Removal of hard deposits. Solid deposits include soot, scale, corrosion products and paint coatings.

Carbon deposits are removed by mechanical, thermal and thermochemical methods. The mechanical method includes:

• scraper surface cleaning
• wire brush
• stone chips
• sandblasting
• hydroabrasive processing

Good results are obtained by cleaning carbon deposits and scale by blowing with stone chips (from the shell of stone fruits) on the OM-3181 unit. Before cleaning, the parts are degreased so as not to contaminate the crumb.

The thermal method is used to remove carbon deposits from exhaust and suction manifolds with excess oxygen or heat parts in thermal furnaces.

The thermochemical method of removing carbon deposits and scale from parts made of ferrous metals consists in immersing them in a melt of salts and alkalis.

Descaling can also be done mechanically and chemically. Steel, cast iron parts are descaled by immersion in a solution consisting of 100-150 g / l of 8-9% hydrochloric acid, followed by rinsing in hot water. Parts made of aluminum alloys are cleaned in a 6% lactic acid solution at a temperature of 40°C.

Corrosion is removed mechanically or chemically. In the first case, the parts are cleaned with steel brushes, sandpaper manually or with special devices, subjected to sandblasting or abrasive-liquid processing. In the chemical method, solutions of sulfuric, hydrochloric or phosphoric acids are used. Corroded surfaces are recommended to be treated with a corrosion modifier before painting.

Rice. Scheme of the washing machine OM-1366G-01: 1 - fan motor; 2 - air suction pipe; 3 - cable; 4, 9 - pipelines; 5 - camera; 6 - electrical cabinet; 7 - wall of the room; 8 - fuel tank; 10 - pump; 11 - filter; 12 - bath; 13 - hatch.

Paint from cabs and plumage of machines is removed mechanically and chemically. The mechanical method (cleaning with steel scrapers and brushes) is used in the CRM farms. More effective is the chemical method, in which the surface is treated with a special wash. The paint swells and separates from the metal surface, so it can be easily cleaned with brushes. Washes SD, SP-6, AFT-1, etc. are used.