The main causes of the accelerated wear of the engine. The reasons for the accelerated wear of the engine in which engines are running faster mechanisms

09.03.2020

All items during operation lose their initial characteristics. The reason for this is wear - the process of changing spare parts, as a result of which the mechanism loses its initial properties.

Visual signs of wear: change in the size and structure of the surfaces of parts.

Types of wear of parts

Changing the characteristics of the spare parts used is a process that is the result of their interaction and use. Part of the changes occurs even with normal operation of the mechanisms. Such changes are called natural and launched when the node is started.

2 types of unnatural wear details:

NORMAL

It is a consequence of improper operation, editing disorders. Leads to gradual failures of technology and deterioration technical status object.

EMERGENCY

As the numerical values \u200b\u200bof normal wear, objects and mechanisms become completely unsuitable.

Factors that affect the pace of wear:

Construction of the mechanism
Accuracy and Cleaning Processing
The strength of the material of a specific part and touching it
Lubrication quality
Conditions of operation of the node (regularity, load character, temperature mode, pressure)
Regularity

Causes causing wear

All reasons can be combined in 3 groups:

Physical / Mechanical

It is the consequence of high loads and exposure to the friction force of one detail about another. Contact spare parts are abrase and cracks, zapapin, roughness appear on their surfaces.

Heat / molecular mechanical

Shared parties are experiencing overheating of high speeds and specific pressure. Because of the sharp rise in temperature, it takes place and the subsequent destruction of molecular bonds of particles inside the metal. Details are boxed and melted.

Chemical / corrosive

It is observed on the surface of metal parts as a result of exposure to water, air, chemicals. Corrosion and corrosion processes occur. To avoid this, it is recommended to use.

It is worth understanding that the cause of wear and breakdowns of parts is not one separately taken factor, but several interrelated.

How to restore worn items?

Basic methods for restoring parts:

Restoration of mechanical and laminated processing

Suitable for parts with flat touching surfaces. The worn place is treated (grind, stable, etc.) and translated into the next size. Mechanical processing is used separately and as the final stage of other methods.

Update welding and surfacing

By surfacing durable metals, the dimensions of damaged parts are restored.

Restoration of metallization details

The size of the worn part is restored by applying molten metal with thin (from 0, 03 mm) and thick (over 10 mm) layer.

Electroplating Sooting (Chrome)

Chromium applying a thin layer (up to 1 mm) provides resistance to mechanical abrasion. The method is similar to metallization, but less universal. Restored parts poorly carry dynamic loads.

Stroiting and gluing plastic

Plastics allow you to obtain stationary connected nodes, as well as stop wear out parts. In contrast to the previous methods, metal and non-metallic parts are subject to plastic recovery. The cost of repairing plastics is significantly lower. With the help of modern materials for casting, you can restore the detail of complex and non-standard geometry.

1. Nominal. (Reinforced) Mileage 0-15 thousand km.Riding in urban mode (we are wearing - Stand) disrupts the temperature balance of the cooling system, leading to an uneven expansion of rubbing parts. There is a very fast trigger of friction pairs with a metal loss, the formation of scaling.

2. Current. (Permissible) Mileage 15-60 thousand kmThe car has become dynamic. Passed a guard - trigger! But the oil consumption appeared. The accumulated deposits (cunning) under the rings form quite serious loops on the cylinders. What did we do to reduce friction?
Operating a car in urban mode (we are going - we are standing) reminds driving on skating on asphalt, and not ice. The main function of the oil is to remove up to 80% of heat from the piston, on the surface of which, with T 1200ºС (gasoline), the working mixture burns. Oil loses viscosity from high temperature. And for the separation of rubbing surfaces, a durable oil film is required.

Good flushing When the oil is replaced, 3-speed rounds, restoring nanotechnology - the key to indispensability.

3. Critical. (Limiting) Mileage 60-120 thousand kmAccuming Nagar (Coke) under rings and in grooves do not allow them to amortize. The rings are burning, valve. The oil consumption increases sharply. A direct contact of the rings with the surface of the cylinder is created. Hans are erased, wear goes catastrophically.

On time, the video code allows 70% to restore the engine by the programs of impact repair, 4-10 times cheaper and without resorting to the cap. Repair.

4. Corrected. Mileage over 120 thousand kmThe engine loses more than 70 grams of metal. Avalanche-like deposits reduce all parameters: pressure, "compression". Requires cap. Repair with defect details. After cap. Repair Mandatory Processing Support + Molecular Vault, to increase the resource by 2-3 times.

Timely detected wear on the 2 or 3 stage of the engine resource - easily eliminated with the help of 3-speed rounds using the suspension and molecular pile - without cap. Repair.

How wear is happening:

Full wear is the loss of more than 70 grams of metal

1. Frequent launches at night warming

2. Incorrect running in a new or capitally repaired engine in high hydrodynamic friction mode (riding in tension at high loads). Vina - Urban traffic jams

3. Engine overheating. In 99% of cases, overheating occurs due to poor heat removal - internal overheating. Dashboard does not state such overheating

4. Cocking - the main factor as this process occurs the heavy fractions of the hydrocarbons of unburned fuel and the lacquer sediments of the oil are appreciated into more viscous, and under the action T - in solid. Difficult resino coke formations (Nagar) are capable of oil transformations, adhere to the surface of the metal and score cavities.

3-4 times accelerate oil tool:
- containing polymer thickeners
- having high sulphate ashost - over 1.2%
-Teer Low Tº Flash - less than 210ºС

Outlet rings scrape the net with oil from the surface of the cylinder, while part of the nagar is removed into the filter, the part is postponed on the inner surface of the engine, the other part scores the grooves piston ringsThe mobility is lost.

Circular ariser:
1. Increases oil consumption
2. Reduces the on-piping pressure (compression ratio)
3. The breaking gases in the Carter very quickly oxidize the oil, it darkens and loses its functions

Cocking reduces the amplitude of the rings fluctuations. The piston sharply presses on the ring, the latter is on the wall of the cylinder. So the metal loss occurs - wear goes.

The main negative physical phenomena,
Destroying engine creating wear:

- Flotation - Destruction and Metal Pattern
- Cavitation - "Buggy" cooling system
- Pompous - Unstable engine operation (speed turns)
- Brusan state - detonation, overheating
- Futing - Education of a very durable nagar formation on pistons

The absence of these 5 phenomena during engine operation is the main law of durability ..

Conducting early diagnosis in new and running vehicles, further service maintenance In our center, will save time and money.

When setting for service (the first substitute for oil and diagnostics in our center):
1. A discount card is issued for free interactive diagnostics.
2. The map gives the right to wash and cutting fuel system, clean the injector with a discount of 3-7%.

When working any production equipment, processes occur associated with a gradual decrease in its performance and changes in the properties of parts and nodes. Accumulating, they can lead to a complete stop and a serious breakdown. To avoid negative economic consequences, enterprises organize the process of wear management and timely updating of fixed assets.

Definition of wear

Wear, or aging, call a gradual decline performance characteristics products, nodes or equipment as a result of changing their shape, sizes or physicochemical properties. These changes arise gradually and accumulate during operation. There are many factors that determine the speed of aging. Negatively affect:

friction;
static, impulse or periodic mechanical loads;
temperature regime, especially extreme.

The following factors slow down aging:

constructive decisions;
the use of modern and high-quality lubricants;
compliance with operating conditions;
timely maintenance, planned warning repairs.

Due to the decline in operational characteristics, the consumer value of products is also reduced.

Types of wear

The speed and degree of wear is determined by the conditions of friction, loads, properties of materials and constructive features of products.

Depending on the nature of the external influences on the materials of the product distinguish the following main types of wear:

abrasive species - damage to the surface with small particles of other materials;
cavitation, caused by explosive collapse of gas bubbles in a liquid medium;
adhesion form;
oxidative view caused by chemical reactions;
thermal view;
fatigue view caused by changes in the structure of the material.

Some types of aging are divided into subspecies, such as abrasive.

Abrasive

It is the destruction of the surface layer of the material during contact with more solid particles of other materials. Characterized for mechanisms working in dust conditions:

mining equipment;
transport, road construction mechanisms;
agreecultural machines. Agreecultural equipment;
construction and production of building materials.

It is possible to counteract him by applying special strengthening coatings for rubbing pairs, as well as changing lubricant timely.

Gasarabrasive

This subspecies of abrasive wear differs from it by the fact that solid abrasive particles are moved in the gas stream. The surface material crumbs is cut, deformed. It is found in such equipment as:

pneumatic lines;
blades of fans and pumps for pumping polluted gases;
domain settings;
components of solid fuel turbojet engines.

Often, the gas-abrasive effect is combined with the presence of high temperatures and plasma flows.

Download GOST 27674-88

Hydroabrasive

The impact is similar to the previous one, but the role of the abrasive carrier does not perform a gas medium, but the fluid flow.

This exposure is subject to:

hydrotransport systems;
nodes of turbines HPP;
components of cleaning equipment;
mountain equipment used for rude washing.

Sometimes hydroabrasive processes are exacerbated by the effect of the aggressive liquid medium.

Cavitational

The pressure drops in the liquid stream that flows around the structures leads to the occurrence of gas bubbles in the relative vacuum area and their subsequent explosive collapse with the formation of a shock wave. This shock wave is the main acting factor of cavitation destruction of surfaces. Such destruction is found on rowing screws of large and small ships, in hydro turbine and technological equipment. Complicate the situation can affect the aggressive liquid medium and the presence of abrasive suspension in it.

Adhesion

With prolonged friction, accompanied by plastic deformations of the running pair of participants, there is a periodic convergence of the surface sections at a distance that allows for the forces of interatomic interaction to express themselves. It begins the interpenetration of atoms of the substance of one part into the crystal structures of the other. The repeated occurrence of adhesion ties and their interrupt lead to the separation of surface zones from the part. Adhesive aging are susceptible to loaded rubbing pairs: bearings, shafts, axes, sliding liners.

Thermal

The thermal type of aging is to destroy the surface layer of the material or in changing the properties of its depth layers under the influence of constant or periodic heating of the design elements to the plasticity temperature. Damage is expressed in crumpled, placing and changing the form of the part. It is characteristic of high-loaded heavy equipment knots, roll rolling mills, hot stamping machines. It can also occur in other mechanisms in disruption of the design conditions for lubricant or cooling.

Fatigue

Associated with the phenomenon of metal fatigue under variables or static mechanical loads. Shear-type voltages lead to development in materials of parts of cracks, causing reduced strength. The cracks of the near-surface layer are growing, combine and stopped with each other. This leads to erosion of small scales of fragments. Over time, this wear can lead to the destruction of the part. Occurs in the nodes of transport systems, rails, wheeled steamah, mining machines, building structures, etc.

Fretting

Freating is the phenomenon of the microening of parts in close contact in the conditions of vibration of small amplitudes - from hundredths of the micron. Such loads are characteristic of rivets, threaded compounds, knaps, slots and pins connecting parts of mechanisms. As Freating aging and detachment of metal particles, the latter perform as an abrasive, exacerbating the process.

There are other, less common specific types of aging.

Types of wear

The classification of types of wear from the point of view of its physical phenomena in the micrometer is complemented by systematization on macroscopic consequences for the economy and its subjects.

In accounting and financial analyst, the concept of wear, reflecting the physical side of the phenomena, is closely related to the economic concept of depreciation of equipment. Depreciation means both a decrease in the cost of the equipment as it aging and attributing a part of this reduction on the cost of products produced. This is done in order to accumulate on special depreciation accounts for the purchase of new equipment or partial improvement of it.

Depending on the causes and consequences distinguish physical, functional and economic.

Physical deterioration

Here is meant the immediate loss of design properties and characteristics of a unit of equipment during its use. Such a loss can be either complete or partial. In the case of partial wear, the equipment is subjected to restoration repairs, returning properties and characteristics of the unit to the initial (or other, pre-agreed) level. With full wear, equipment is subject to write-off and dismantling.

In addition, physical wear is also divided into the kind:

First. The equipment is wear out during scheduled use in compliance with all rules and rules established by the manufacturer.
Second. The change in properties is due to improper operation or by the factors of force majeure.
Emergency. The hidden change in properties leads to a sudden emergency failure.

Listed varieties apply not only to the equipment as a whole, but also to separate items and nodes

This type is a reflection of the process of moral obsolescence of fixed assets. This process is to appear in the market of the same type, but more productive, economical and safe equipment. The machine or installation is physically still fulfilled and can produce products, but the use of new technologies or more advanced models appearing on the market makes the use of outdated economically unprofitable. Functional wear can be:

Partial. The machine is unprofitable for the completed production cycle, but is quite suitable for the implementation of some limited set of operations.
Full. Any use leads to damages. Unit subject to write-off and dismantling

Functional wear is also divided by causing it to factors:

Moral. Availability of technologically identical, but more advanced models.
Technological. Development of fundamentally new technologies for the release of the same type of product. Leads to the need to restructure the entire technological chain with a complete or partial update of the composition of fixed assets.

In the event of the appearance of a new technology, as a rule, the composition of the equipment is reduced, and the complexity drops.

In addition to physical, temporary and natural factors for the safety of equipment characteristics, indirect influence and economic factors are provided:

Fall demand for manufactured goods.
Inflation processes. Prices for raw materials, components and labor resources are growing, at the same time proportional increase in prices for enterprise products does not occur.
Price pressure of competitors.
Rising the cost of credit services used for operating activities or to update fixed assets.
Unfliance price fluctuations in raw materials markets.
Legislative restrictions on the use of equipment that does not meet the safety standards ambient.

Economic aging and loss of consumer qualities are subject to both real estate and production groups of fixed assets. Each enterprise contains registers of fixed assets in which their wear and movement of depreciation savings are taken into account.

The main causes and ways to determine wear

To determine the degree and cause of wear, at each enterprise, the Commission on the main funds is created and operates. Equipment wear is determined by one of the following ways:

Observation. Includes visual inspection and measurement and test complexes.
By deadline. Determined as the ratio of the actual term of use to the normative. The value of this relationship is taken as the amount of wear in percentage terms.
the enlarged assessment of the state of the object is performed using special metrics and scales.
Direct measurement in money. The cost of acquiring a new similar unit of fixed assets and costs of recovery is compared.
profitability of further use. An increase in income is evaluated, taking into account all costs to restore properties compared to theoretical income.

What methods to apply in each case - decides the commission for fixed assets, guided by regulatory documents and the availability of source information.

Methods for accounting

Depreciation deductions designed to compensate for equipment aging processes are also permissible to determine several methods:

linear, or proportional calculation;
a method of reduced residue;
under the summary period of production;
in accordance with the volume of issued products.

The choice of techniques is carried out when creating or deep reorganization of the enterprise and is consolidated in its accounting policies.

The operation of equipment in accordance with the rules and regulations, timely and sufficient contributions to depreciation funds allow enterprises to maintain technological and economic efficiency at a competitive level and delight their consumers with high-quality goods at reasonable prices.

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Introduction

1.1 Abrasive wear
1.2 fatigue wear
1.3 Wearing during jealous

Conclusion

Introduction

In the process of operation of the car, as a result of the impact on it, a number of factors (the impact of loads, vibrations, moisture, air flows, abrasive particles, when hitting the car dust and dirt, temperature effects, etc.), there is an irreversible deterioration of its technical condition associated with wear and damage to its details, as well as a change in a number of their properties (elasticity, plasticity, etc.). Wearing hydro-erosive abrasive

The change in the technical condition of the car is due to the work of its nodes and mechanisms, the impact of external conditions and storage of the car, as well as random factors. Random factors include hidden defects of car parts, congestion of construction, etc.

The main permanent reasons for changing the technical condition of the car during its operation was wear, plastic deformations, fatigue destruction, corrosion, as well as physico-chemical changes in the material of parts (aging).

1. Types of destruction of metal surfaces

To effectively manage the processes of changes in the technical condition of the machines and justify the activities aimed at reducing the intensity of the wear of the parts of the machines, in each particular case, to determine the type of wear of the surfaces. To do this, set the following characteristics: type of relative movement of surfaces (friction contact scheme); The character of the intermediate environment (view lubricant or working fluid); The main wear mechanism.

In the mating machines, there are four types of relative movement of working surfaces of parts: sliding, combustion, blow, oscillation (moving having the nature of relative oscillations with an amplitude of 0.02-0.05 mm).

In the form of the intermediate medium, wear is distinguished by friction without lubricant, by friction with a lubricant material, with friction with abrasive material. Depending on the properties of materials of parts, lubricant or abrasive material, as well as on their quantitative relations in conjugations, during operation, the destruction of surfaces of various species arise.

Wear separated into the following types: Mechanical (abrasive, hydro and gas abrasive, erosion, hydro and gas - erosive, cavitation, fatigue, wear during the jamming, wear during fretting); corrosion-mechanical (oxidative, wear during fretting corrosion); Wearing under the action of electric current (electro-erosion).

Mechanical wear occurs as a result of mechanical effects on the friction surface.

Corrosion-mechanical wear is a consequence of a mechanical impact, accompanied by a chemical and (or) electrical interaction of the material with the medium.

The electro-erosion is called the erosion wear of the surface as a result of the exposure of discharges during the passage of the electric current. In the machines, this type of wear is found in elements of electrical equipment in generators, electric motors, as well as in electromagnetic starters.

IN real conditions Mattures of machines are observed simultaneously several types of wear. However, as a rule, it is possible to establish a leading type of wear, limiting the durability of parts, and separate it from other concomitant types of destruction of surfaces, which slightly affect the performance of the conjugation.

The mechanism of the main type of wear is determined by studying worn surfaces. Observing the nature of the manifestation of the wear of the friction surfaces (the presence of scratches, cracks, traces of coloring, the destruction of oxide film) and knowing the properties of the materials of parts and lubricant material, as well as the data on the presence and nature of the abrasive, intensity of wear and the mode of conjugation, can be fully justified. On the form of wear of the conjugation and develop measures to increase the durability of the machine.

1.1 Abrasive wear

Abrasive is called the mechanical wear of the material as a result of mainly cutting or scratching effects on it of abrasive particles located in a free or fixed state. Abrasive particles, having a higher than metal, hardness, destroy the surface surface and dramatically increase their wear. This type of wear is one of the most common. In road vehicles, more than 60% of wear can be abrasive. Such wear is found in the details of pivot compounds, open bearings of sliding, parts of the working bodies of road vehicles, details running parts and etc.

The main source of abrasive particles in the interface of the machines is the environment. In 1 m3 of air contains from 0.04 to 5 g of dust, 60 ... 80% consisting of suspended particles of minerals. Most of the particles have dimensions D \u003d 5 ... 120 μm, i.e. commensurate with gaps in pairing road machines. The main components of dust: SiO2 silicon dioxide, FE2O3 iron oxide, Al, Ca, Mg, Na compounds and other elements.

In determining the type of wear of the elements of machines, it is necessary to distinguish from hydro and gas-abrasive wear erosion, hydrogazoerosium and cavitation wear.

The erosion is called the mechanical wear of the surface as a result of the effect of fluid flow and (or) gas.

Hydro-erosive (gas - erosion) wear is erosion wear as a result of the effect of fluid flow (gas).

Cavitational is called hydro-erosive wear when the solid body moves relative to the liquid, in which gas bubbles slam close near the surface, which creates a local pressure or temperature. The wear of this species is most often found in the elements of pipelines and in collectors in the absence of abrasive particles in the working fluid or gas. For road I. building machines Erosion types of wear are not characteristic.

1.2 fatigue wear

The fatigue is called mechanical wear as a result of fatigue destruction when re-deforming the microvapors of the material of the surface layer. Such wear is observed in most pairs of road machines as a concomitant type of wear. It occurs both by friction of rolling and with friction slip.

The process of fatigue wear is usually associated with repeated voltage cycles in contact or slipping. In the process of the interaction of surfaces in their upper layers there are fields of stresses. Scheme of voltage distribution when the cylinder contact with the plane calculated by the method of finite elements. In the process of friction on the working surface of parts, the maximum compression voltages arise, and in the depth of the material of the part, the directed tangent voltages with a maximum of a distance from the contact point are distributed.

The intensity of fatigue wear is determined by the following factors: the presence of residual stresses and surface voltage concentrators (oxides and other major inclusions, dislocations); surface quality (micropographs, pollution, dents, scratches, scratches); Load distribution in the conjugation (elastic deformation, skew parts, clearance); type of friction (rolling, sliding or rolling with slippage); The presence and type of lubricant material.

There are two models of the process of fatigue wear of the material. The theory of fatigue wear, developed by a group of scientists under the leadership of I.V. Krageelsky. According to this theory, wear particles from the friction surface can be separated and without the introduction of microprips of one part to the surface layers of another detail of the conjugation. Wearing can occur due to the fatigue of microvipos of the material arising from multiple compressive and stretching efforts.

The fatigue wear is most often observed under high contact loads while rolling and slipping one surface on another. In such conditions, there are, for example, gear wheels, severe gears and rolling bearings, gear crowns. The fatigue wear of the working surfaces of parts is accompanied by an increase in noise and vibration as wear increases.

The fatigue wear of the material may be moderate and progressive. Conventional moderate wear for most friction pairs is not dangerous, and details that have fatigue damage can be used for a long time. Progressive wear occurs at high contact stresses, accompanied by intense destruction of the surface and can lead to a breakdown of parts (for example, the gear tooth).

With intense abrasive wear of the working surfaces, their destruction occurs faster than the formation of fatigue cracks, therefore, as a rule, pitting is not observed in such cases.

The fatigue wear is also manifested in the interaction of parts from elastomeric materials. The elastic properties of these materials make it possible to reproduce the roughness of the opposite solid surface during the slip process, which, in turn, leads to a multiple cyclic loading of the material. If the protrusions of the irregularities of the solid surface have a rounded shape and do not cause abrasive wear, the damage may occur in the subsurface layers of the elastomer under the action of repeating stresses of compression, stretching and alternating tangent stresses. This fatigue mechanism causes the wear of relatively low intensity, which increases significantly under the action of cyclic stresses for a long time.

1.3 Wearing during jealous

Wearing during the jamming occurs as a result of setting, the deep breaking of the material, transfer it from one friction surface to another and exposure to the irregularities on the conjugate surface. Wearing this species is one of the most dangerous and destructive. It is accompanied by a durable compound of contacting friction surfaces. In the process of friction, the relative movement of the surfaces leads to the separation of the metal particles of one surface and adding them to another firm surface.

In the mechanism of wear when she has an important role plays atomic molecular interaction of parts of parts, occurring during convergence of surfaces. Unlike the wear of other species, which requires a certain time on the development of the process and the accumulation of destructive damage, while jamming the destruction of the surface occurs rather quickly and leads to severe forms of damage (scams and sinks).

The process of forming metal bonds depends on the properties of conjugate surfaces (their nature, hardness), as well as on the methods of their processing. In the presence of oxide films on the surface of the metals, the process of jamming also depends on the properties of these oxides. Protective films that firmly connecting with the main metal and capable of rapidly restored during the destruction, prevent the collection of metals.

Wearing during the shealing of metals occurs due to violation of the rule of a positive gradient of mechanical properties in depth under friction conditions without lubricant or with its insufficient amount. In the friction of rolling under the conditions of boundary lubrication, wear is also observed caused by grasp materials and jamming. Classroom occurs at a local grease film breaking and installing metal contact. This is possible not only with the termination of the supply of lubricant, but also due to the overall overload of the conjugation, a sharp increase in oil temperature in surface layers, local temperature flashes, etc.

Wearing during the jail is most often found in gear engagement. By the ability to confront hot transmission of all types in the same conditions of loading, the gears can be positioned in the following order: cylindrical transmissions with internal and external engagement; conical transmissions with straight, oblique and spiral teeth; Hypoon and screw transmissions having the lowest contamination resistance. This is explained by the fact that hypoid and screw gears have the greatest slip of the teeth in the engagement. Wearing during jamming is also occurring in ball and roller bearings, in severely loaded rolling supports.

1.4 Corrosion-mechanical wear

Corrosion-mechanical wear is characterized by the process of friction material that has entered into chemical interaction with the medium. At the same time, new, less durable chemical compounds are formed on the metal surface, which during the operation of the pairing are removed with wear products. The corrosion-mechanical wear includes oxidative wear and wear during fretting corrosion.

The oxidative is called wear, in which the basic effect on the destruction of the surface has a chemical reaction of material with oxygen or oxidizing environment. It occurs when rolling with lubricant or without lubricant. The speed of oxidative wear is small and is 0.05 ... 0.011 μm / h. The process is activated with an increase in temperature, especially in a humid environment.

Wearing with fretting-corrosion is the corrosion-mechanical wear of contacting bodies with small oscillatory relative movements. This type of wear differs from wear with the fretting of mechanical wear of contacting bodies with low oscillatory relative movements. The main difference lies in the fact that the wearing in fretting occurs in the absence of an oxidizing environment without the manifestation of the chemical reaction of materials of parts and wear products with oxygen. Considering this, it is not difficult to draw an analogy in the mechanisms for the development of wear at fretting and fretting-corrosion.

Wearing during fretting and fretting-corrosion usually occurs on the conjugate surfaces of the shafts with the wheels pressed on them, clutches and rings of rolling bearings; on the axes and hubs of the wheels; on the support surfaces of the springs; on the protracted joints, the fitted surfaces of the knaps and grooves; On the supports of engines and gearboxes. Prerequisite The occurrence of fretting corrosion is the relative slippage of the conjugate surfaces, which can be caused by vibration, reciprocating movement, periodic bend or twisting of the conjugate parts. The fretting process is accompanied by a setting, oxidation, corrosion and fatigue destruction of micro components.

As a result of fretting-corrosion, the surface endurance limit is reduced by 3-6 times. On the surfaces of parts in places of conjugates, nozzles, baking sheets, feed, sinks, as well as surface microcracks are formed. A distinctive feature of wear due to freaking-corrosion is the presence of sink friction surfaces, in which compressed oxides having a specific color are concentrated. In contrast to the wear of other species with fretting corrosion, wear products in the main mass cannot exit the contact area of \u200b\u200bthe working surfaces of parts.

Wearing with fretting-corrosion entails a violation of the dimensional accuracy of the connection (if part of the wear products finds output from the contact zone) or jamming and jamming of detachable connections (if wear products remain in the friction zone). For fretting corrosion, a low rate (about 3 mm / s) of the relative movement of surfaces and the path (0.025 mm) of friction equivalent to the amplitude of oscillations, with a frequency of oscillations up to 30 Hz and above; Localization of surface damage on valid contact sites due to small relative displacements; Active oxidation

When the interaction of elastomeric materials with metal parts is also observed a phenomenon of setting. Elastomer wear out if the friction coefficient between it and the solid surface is quite large, and the strength of the elastomer on the rupture is small. If the surface layers of the material are in a state of maximum deformation, then a scratch or a small crack appears in the direction perpendicular to the slide direction. Next, there is a gradual breaking of a part of the elastomer elastic material, which is in a state of setting with a solid surface. At the same time, the elastomer layer, separated from the surface, is twisted into the roller and forms a particle of wear. The intensity of the elastomer wear in this case is significantly depends on the temperature, load and type of lubricant material. Selecting the lubricant taking into account the external conditions and elastic properties of the elastomer, you can completely eliminate this type of wear.

The process of wear during fraging corrosion under friction conditions without lubricant can be divided into three stages.

The first stage is accompanied by the destruction of protrusions and oxide films due to cyclically repeated oscillatory relative movements of contacting surfaces under the action of high loads. The processes of hardening materials and plastic deformation of the protrusions of microdelnics, causing convergence of surfaces. Rapid of surfaces causes molecular interaction and setting the metal in separate points of contact. Destruction due to the fatigue of protrusions and setting nodes generates wear products, part of which is oxidized. This stage is characterized by elevated wear with monotonously decreasing wear rate.

In the second stage, fatigue damage accumulates in surface layers. In the friction zone, a corrosion-active medium is formed under the action of oxygen air and moisture. A electrolytic medium is created between the surfaces, which intensify the process of oxidation of metal surfaces and their corrosion destruction. For this stage, the stabilization of the wear process is characteristic, a decrease in the wear rate compared with the velocity rate at the first stage.

In the third stage, due to fatigue corrosion processes, the sophisticated surface layers of metals begin to intensively collapse with gradually increasing speed. The process has a corrosion-fatigue nature of destruction.

The intensity of the destruction of surfaces during phreatic corrosion depends on the amplitude and frequency of oscillations, load, properties of the materials of parts and the environment.

2. Basic causes of wear and body damage

Worn and damage to the body may be caused various reasons. Depending on the cause of the malfunction, they are divided into operational, structural, technological and arising due to improper storage and body care.

During operation, elements and body nodes experience dynamic stresses from bending in a vertical plane and twisting, load from their own mass, weight of cargo and passengers.

Significant stresses are also contributed to the wear of the body and its assemblies, which arise as a result of the body fluctuations not only when it moves on the irregularities and possible jokes and shocks when driving on these irregularities, but also due to the operation of the engine and the errors in balancing the rotating knots of the car chassis (especially Cardan shafts), as well as as a result of the bias of the center of gravity in the longitudinal and transverse directions.

Loads can be perceived by the body completely if the car does not have a chassis frame, or partly when installing the body on the frame.

Studies have shown that the variables by the magnitude of the voltage act on the elements of the body during the operation of the car. These stresses cause fatigue accumulation and lead to fatigue destruction. Fatigious destruction begin in the area of \u200b\u200bstress accumulation.

In bodies of cars entering overhaulThere are two basic groups of damage and faults: damage appearing as a result of increasing changes in the body.

These include natural wear, occurring in the process of normal technical exploitation car, due to a permanent or periodic impact on the body of such factors such as corrosion, friction, rotting of wooden parts, elastic and plastic deformations, etc.; Malfunctions, the appearance of which is associated with the action of a person and are a consequence of constructive flaws, factory undersensation, violations of the body of the body and maintenance rules (including emergency), poor-quality repair of the body.

In addition to the normal physical wear, during the operation of a car in difficult conditions or, as a result of the violation of the rules of care and prevention, an accelerated wear may occur, as well as the destruction of individual parts of the body.

Characteristic types of wear and body damage during the operation of the car are metal corrosion arising on the surface of the body under the influence of chemical or electromechanical effects; violation of the density of rivet and welded joints, cracks and ruptures; Deformation (dents, skews, deflection, warping, rejected).

Corrosion is the main type of wear of the metal body of the body.

In the metal parts of the body, the electrochemical type of corrosion is most often found, in which the metal reacts with an electrolyte solution adsorbed from the air, and which appears as a result of both the direct injection of moisture on the unprotected metal surface surfaces and as a result of condensate formation in its inter-branch space ( Between the internal and outer panels of doors, sides, roofs, etc.). Corrosion is particularly developing in places, difficult to access and clean in small gaps, as well as in flanging and edge bending, where the moisture that periodically falls into them can be maintained for a long time.

Thus, dirt, salt and moisture, which stimulate the process of corrosion development can be collected in the wheeled niches; The bottom of the body is not sufficiently resistant to the effects of corrosion factors. The composition of the corrosion has a great influence on the atmosphere, its pollution with various impurities (emissions of industrial enterprises, such as sulfur dioxide, formed as a result of fuel combustion; ammonium chloride, falling into the atmosphere due to evaporation of seas and oceans; solid particles in the form of dust), and Also ambient temperature and other solid particles contained in the atmosphere or on the surface of the body from the canvas are also caused abrasive wear of the metal surface of the body. With increasing temperature, the corrosion rate increases (especially in the presence of aggressive impurities and moisture content in the atmosphere).

Winter coatings of the road Salt to remove snow and ice, as well as the work of the car on sea coasts lead to an increase in the corrosion of the car.

Corrosion destruction in the body are also found as a result of contacting steel parts with details made of some other materials (duralumin, rubber containing sulfur compounds, plastic based on phenolic resins and others, as well as as a result of metal contact with parts made of very wet lumber. containing a noticeable amount of organic acids (formic et al.).

Thus, studies have shown that during contact steel with poly-isobutylene, the rate of metal corrosion per day is 20 mg / m2, and at the contact of the same steel with a silicone rubber - 321 mg / m2 per day.

This type of corrosion is observed in places of formulation of various rubber seals, in places of adjustment to the body of chrome decorative details (headlights, etc.).

To the emergence of corrosion on the surface of the body parts, contact friction also provides a place with the simultaneous effect of the corrosion medium and friction, with the oscillatory movement of the two metal surfaces relative to each other in the corrosion medium. This type of corrosion is subject to the door around the perimeter, the wings in the places of connecting them to the body bolts and other metal parts of the body.

When car painting, the body carefully prepared to the color of the body surfaces and contaminated air may occur. This is not enough high-quality coating also leads to corrosion of the body.

The process of corrosion of the body occurs either evenly on a significant area (surface corrosion is shown in Figure 1), or the corrosion is in the thickness of the metal, forming deep local destruction - sinks, stains in separate points of the metal surface (point corrosion is shown in Figure 2).

Figure 1 - surface corrosion on the wing of the car.

Figure 2 - point corrosion by car.

Solid corrosion is less dangerous than the local, which leads to the destruction of the metal parts of the body, the loss of strength to the sharp decrease in the limit of corrosion fatigue and the corrosion fragility characteristic of the body facing.

Depending on the working conditions that contribute to the occurrence of corrosion, parts and components of the body can be divided into having open surfaces facing a canvas (bottom of the floor, wings, wheel arches, door thresholds, the bottom of the radiator cladding), on having surfaces that are in The limits of body volume (frame, trunk, top of the floor), and on having surfaces that form a closed isolated volume (hidden parts of the frame, bottom of the outdoor door facing, etc.).

Corps cracks occur when they hit due to violation of the technology of metal processing technology (shock multiple steel treatment in cold condition), poor build quality in the manufacture or repair of the body (significant mechanical efforts when connecting parts), as a result of the use of low quality steel, the effects of metal and corrosion With the subsequent mechanical load, defects of assembling nodes and parts, as well as not enough durable knot design.

Cracks can be formed in any part or part of the metal case, but most often in places prone to vibration.

Figure 3 shows the main body damage on the example of the car gas - 24.

Figure 3 - Damage found in the Body of the car GAZ-24 "Volga"

1 - cracks on the mudguard; 2 - disruption of the welded connection of the strut or the rush of the govik with the frame of the frame; 3 - cracks on the strut; 4 - cracks on the front panel and the mudguards of the front wheels; 5 cracks on windows racks; 6 - deep dents on the windows rack panel; 7 - skew of the windows opening; 8 - separation of the front seat bracket; 9 - cracks on the body base casing; 10 - disruption of welded bodies parts; 11 - reinforcing gutter; 12 - dents on outdoor panels closed with details from the inside, irregularities remaining after editing or richtovka-13 - local corrosion at the bottom of the rear window; 14 - the separation of the pandexes in the places of attachment or cracks on the racks; 15 and 16 - local corrosion of the trunk cover; 17 - Targeting bracket of the trunk lock; 18 - local corrosion in the rear of the body base; 19 - dents on the bottom of the cow's rear panel in the places of fastening the rear lights; 20 - local corrosion at the bottom of the mudguard - 21 - corrosion raid and other small mechanical damage; 22 - local corrosion arch wheel; 23 - rear wing mudguard rushing; 24 - a violation of the welded. In combination of mudguard with an arch; 25, 32 - cracked on the basis of the seats fastening places; 26 - local corrosion at the rear door stand and on the base of the body. An exciting rear spar amplifier; 27 - cracks on the basis of the body in places of attachment of the rear springs and others brackets; 28 - dents on the panel of the rack and the reckling of the central rack; 29 - separation of holders of the locks of the lock and the body door loop; 30 - local corrosion at the bottom of the middle side of the sidewall; 31 - local corrosion and cracks of the base base of the body; 33 - Dissars of door openings of the body; 34 - solid corrosion of base thresholds; 35 - dents on spars base base (gaps); 36 - breaking the thread on the plates of fixing fixture and door loops; 37 - Out of the door lock cover; 38 - dents (possibly with breaks) on the sidewall panel of the body; 39 - local corrosion at the bottom of the front rack; 40 - impaired anti-corrosion coating; 41 - Gay-coderzhatley separation; 42 - concurrentness of the coordinates number 1; 43 - cracks on the front panel in the places of the strut; 44 - separation of the mounting bracket front buffer; 45 - cracks on the radiator shield; 46 - local corrosion on the amplifier split; 47 - Cracks in places of fastening of the spar; 48 - attenuation of the rivet connection of the bracket; 49 - Developing holes under the finger of the spring earrings and the front bracket of the rear springs; 50 - separating the amplifier of the body base of the body; 51 - wear of the shock absorber fastening; 52 - Cracks in mounting places brackets fuel tank; 53 - dents with sharp corners or gaps on the bottom panel; 54 - solid corrosion on the bottom of the rear panel; 55 - cracks in the depreciation places; 56 - Cracks on the Cardan Shaft Casing

The destruction of welded joints in nodes, parts of which are connected by point welding, as well as in solid welds of the body can occur due to poor-quality welding or impact of corrosion and external forces: the vibration of the case under the action of dynamic loads, uneven distribution of goods during loading and unloading of the body.

Destruction data are presented in Figure 4.

Figure 4 - destruction of welded compounds under the influence of corrosion

Worn as a result of friction occurs in the details of the reinforcement, axes and holes of the loops, the upholstery, in the holes of the rivet and bolted connections.

Celers and are released in the panels, as well as defamations and bias in the body appear due to residual deformation when they hit or poorly performed works (assembly, repair, etc.).

The concentration of stresses in the compounds of individual elements of the housing in openings for doors, windows, as well as the joints of the elements of large and low rigidity can be the cause of the destruction of parts if they are not enhanced.

In the structures of the body, the necessary hard connections are usually provided, the enhancement of individual sections with additional details, extruding the rigid ribs.

However, in the process of long-term operation of the body and in the process of its repair, separate weak links can be revealed in the body housing that require gain or change the design of nodes to avoid the appearance of secondary breakdowns.

Conclusion

To change the technical condition of the car, conditions of operation are significantly influenced by: road conditions (technical category of road, view and quality of road surface, slopes, climbing raises, rounding radii road), motion conditions (intensive city traffic, road traffic), climatic conditions (ambient temperature, humidity, wind load, solar radiation), seasonal conditions (dust in summer, dirt and moisture in the fall and spring), environment aggressiveness (sea air, salt on the road in winter, reinforcing corrosion), as well as transport conditions (car load).

As a result of the execution of the abstract, the main types of car body destruction of the car were studied.

These include such destruction as fatigue wear and corrosion-mechanical wear.

To reduce corrosion parts of the car and primarily the body must maintain their purity, to carry out timely care for the paintwork and its recovery, to produce anticorrosive treatment of hidden body cavities and other corrosion parts.

To prevent fatigue destruction and plastic deformations, it is strictly followed by the rules of operation of the car, avoiding its work on the limit modes and with overloads.

List of sources used

1 Basics of performance technical Systems studies. For universities V.A. Zorin Academy, 2009. - 206 p.

2 reliability vehicle "Fundamentals of the theory of reliability and diagnostics" / V. I. Calm. - Orenburg: Publishing house OGU, 2000. - 100 p.

3 Reliability of mobile machines / K.V. Schurin; M-in education and science grew. Federation: OGU, 2010. - 586 p.

4 Increasing the durability of transport machines: studies. Manual for universities / V. A. Bondarenko [and others]. - M.: Mechanical Engineering, 1999. - 144 p.

5 Basics of the theory of reliability of motor vehicles: studies. - Method. Hands. For students in the event. Forms of training specialties "150200, 230100" / V. I. Rosidoye. - Orenburg: OGU, 2000. - 36 p.

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