Fire has been known to mankind since primitive times. Most likely, our ancestors got it as a result of natural phenomena, such as thunderstorms. Someone very observant and smart discovered that fire not only scares and burns, but also warms. Then everything went from strength to strength: people learned to preserve smoldering coals, then they figured out what exactly could burn, and which of the materials around them did not burn, even if they cracked! When primitive people moved from fireproof caves to artificial dwellings, then we had to urgently come up with the word “fire”. Fires destroyed homes, tools, and food. People died in fires. And they continue to die to this day. Now in Russia, an average of 56 people die in fires per day.
It turns out that today, when it is ridiculous to even compare our houses with the primitive dwellings of troglodytes, when ingenious means of fighting fire have been invented, when a powerful fire-fighting service exists at the expense of the state, we cannot fight the fiery element on an equal footing.
From the above, two main conclusions can be drawn. First: fire is a formidable force and second: not everyone has yet realized the danger of this threat.
In its physical essence, combustion is a rapidly occurring chemical reaction with the release of heat and light. In a narrow sense, combustion is the process of oxidation of a combustible substance with atmospheric oxygen. Although in some cases combustion can occur in the absence of oxygen. If gases are formed as a result of combustion, the reaction is accompanied by a flame. A highly luminous flame occurs when solid particles, such as coal, are present in the combustion zone. And since carbon is integral part any organic compound, it is clear why you can read by the light of a fire.
During combustion, active intermediate products are released, which greatly accelerate the process. Chain reactions begin, and only two factors become of primary importance for extinguishing a fire: timeliness and sufficiency. A cigarette butt thrown into dry grass can easily be trampled. For extinguishing small fire A bucket of water is enough. But this is in the first seconds. And then the timeliness of our reaction and the sufficiency of means to extinguish the fire are expressed in the cry: “Guard, we are burning!” Even a ton of water is no longer enough, and the rate of fire spread is increasing like an avalanche.
It is in the high speed of fire spread that their insidiousness lies. No matter how highly organized the fire service is, no matter how modern and effective the fire extinguishing means are, some time passes before the fire can be fought, which turns, figuratively speaking, a simple cigarette butt into a disaster.
There are two ways to ignite a substance: from an external source and self-ignition. In the case of an external source, everything depends on the magnitude of the initial thermal impulse (cigarette butt, match, torch) and the nature of the substance being ignited. It is easy to set fire to a stack of straw with one match because the amount of heat that a single match releases is enough to start the combustion reaction of a flammable substance - straw. You won't be able to light a damp log with a match.
In the case of self-ignition, the external temperature must become such that the oxidation reaction of the substance with oxygen begins - combustion. For paper, this temperature is only 218°C. The great American science fiction writer Ray Bradbury has such a book “Fahrenheit 450”. This is the same value for the ignition temperature of paper, only on a different scale. Imagine a book forgotten by a harmless stove. The stove heats up, the book heats up. At some point, the amount of heat coming to the paper will exceed the amount of heat that the paper gives off to the environment, and the result is a household fire.
For this physical reason, it is hard to believe that primitive people obtained fire by friction. Somewhere on the equator this is quite acceptable. But try to generate so much heat by friction that in the damp and cold taiga environment 90% of your efforts have not disappeared! But in the same taiga there may be a fragment of a bottle lying around, which will focus the rays of the modest northern sun on a very small surface of last year’s needles. This can start a forest fire. The source of trouble is still the same - man!
Our houses are built from traditional and new materials. Traditional ones include: wood, red brick, plaster, tiles, clay. Other materials - concrete, sand-lime brick, plastics, composite (consisting of different materials) building materials, metal - all these are the fruits of civilization that make it possible to build panel houses, monolithic skyscrapers, bridges, TV towers and much more.
From a fire safety point of view, all materials are divided into non-combustible, non-combustible and combustible.
Fireproof materials are considered to be those that do not ignite, smolder or char at high temperatures. Examples of fireproof materials: brick, concrete, metal, glass.
Fire-resistant are considered materials that, when exposed to high temperatures, are difficult to ignite and continue to burn and smolder only in the presence of a fire source. Such materials include: composite materials(foam concrete with a heat-insulating layer, wood treated with fire retardants).
Combustible materials are those materials that ignite at high temperatures and continue to burn and smolder even when the source of fire is removed. This group, of course, includes wood and composite materials based on it (chipboards, fiberboards, plywood). This also includes materials made of rubber, plastic, leather, linoleum, rolled roofing materials(roofing felt, roofing felt).
Main physical characteristics, important understanding of the properties of materials and their ability to withstand fire are:
· strength;
· porosity;
· thermal conductivity;
· fire resistance;
· water absorption.
Strength is the ability of a material to resist destruction under the influence of external load.
Specific gravity- the ratio of body weight to its volume. Numerically equal to density. Measured in g/cm3.
Porosity- a property due to the structure of the substance, the presence of empty spaces between individual grains. Measured as a percentage.
Thermal conductivity- the ability of materials to transfer heat through thickness from one surface to another.
Fire resistance— the ability of materials to withstand high temperatures during fires without destruction.
Water absorption- the ability of materials to absorb and retain water. It is measured as a percentage as the ratio of the volume of water absorbed to the volume of the sample.
Having familiarized ourselves with the physical characteristics of materials that interest us from the point of view of fire safety, we can comment on them as follows:
Strength is the main quality building material. Monolithic reinforced concrete and metal have no equal here. The steel Eiffel Tower stands in Paris, having its own weight of 9 thousand tons! There are reinforced concrete giant skyscrapers in Dubai, Mexico City, New York and Sydney. The Ostankino Tower stands.
Specific gravity is important for creating a safety margin. That is, the structure is capable of resisting heavy loads when its strength is not spent fighting its own weight. This means that lightweight materials make it possible to count on greater stability.
Porosity is a wonderful quality. The best heat insulator is air. The more pores filled with air in a material, the lower its thermal conductivity and the more preferable it is for building houses. Here the leaders are foam concrete, expanded clay concrete, mineral wool and mounting foams.
Thermal conductivity is an extremely important concept, since not only depends on the ability to transfer heat through the thickness of the material Fire safety material, but also the speed of fire spread. Metal conducts heat well. And cold. Try licking a piece of iron in the cold. No, better not! Take my word for it - your tongue will freeze right away. And you can lick a piece of wood for your own pleasure without harmful consequences. A great illustration of the concept of thermal conductivity! Materials with a high degree of porosity, as a rule, also have low thermal conductivity, which is very good.
Water absorption is the ability of a material to resist fire by absorbing water. There is such a fire term - “spill”. It probably came from “heavy rain.” During pouring, smoldering fires are destroyed and surfaces are cooled. In order to turn 1 g of water into steam, you need to spend 80 kcal. So the fire spends its energy on steam generation, which is what we actually wanted. This leads to another important observation: water is an excellent means of fighting fire.
Getting acquainted with water as a fire extinguishing agent should begin not with the “Cat House”, but much earlier. Back in 200 BC, the first fire water pump was invented. The first fire department appeared in Russia in 1803, and in 1853 there were fire departments in 450 cities. The respected profession of firefighter (axeman) and the honorable position of fireman (fireman) appeared. Over time, the horse-drawn water barrel was replaced by a tank truck. The manual rocker pump was replaced by high-performance pumps. But the principles of fire extinguishing remain the same, since the enemy - fire - has not changed at all over time.
Continuing to talk about water, it is worth noting that the speed and effectiveness of fire extinguishing is proportional to the amount of water supplied to the fire. Pumps (pumps) mounted on fire trucks are capable of providing a capacity of 30 l/sec or more, and mobile fire modules - up to 400 l/sec. By the water with her physical properties— density, viscosity, fluidity; in accordance with the laws of hydrodynamics, the possibilities of transmission over a distance are far from unlimited. Friction against the walls of pipelines, curvatures, and narrowings cause difficulties in the transfer of water and reduce productivity. Down up powerful pump can supply water under pressure to a height of 100 m, but the laws of physics will not allow sucking up water using a vacuum from a depth of more than 7 m.
Water is supplied from the pump using flexible fabric hoses, at the ends of which there are connecting heads (locks) that allow the hoses to be connected to each other. Quick release connections, bayonet type. This type of bayonets (bayonets) were once attached to guns. Fire hoses come in a variety of diameters, but they can be easily differentiated by the diameter of the matching connection heads.
To connect several hoses or hoses of different diameters to the pump, there are branches, each branch (stroke) of which has its own valve. Branches are made from aluminum alloys for ease of handling.
To supply water to the fire, a barrel is attached to the end of the hose, which allows water to be supplied as a stream or sprayed.
When working with hoses, you should not forget that overloads occur at the breaks, which can lead to rupture of the hose, and in this case the water supply stops. With good pressure, hold the sleeve and point the barrel at in the right direction It’s extremely difficult for one person. He usually needs the help of one or two other people.
There are also big ones fire monitors, but only professional firefighters work with them.
In addition to water, compositions that increase the effectiveness of extinguishing are supplied to the fire flames - foams, powders, emulsions. This is especially important in cases where flammable liquids are burning - oil, gasoline, etc. Water is no help here, since these liquids have a density lower than that of water, float to the surface and continue to burn.
Fires that originate from live electrical installations are extinguished using compressed carbon dioxide, which is not a conductor of electricity.
Burning chemicals are extinguished with special compounds that react with the burning substance to release carbon dioxide.
Local fires are extinguished with fire extinguishers. Fire extinguishers are divided into foam, carbon dioxide, powder, emulsion.
Before using a fire extinguisher, you must read the text printed on its body. The fact is that the wide variety of brands and designs of fire extinguishers and extinguishing materials does not allow us to confidently judge the purpose of the device. For example, the newest emulsion fire extinguishers are marked: “Suitable for extinguishing electrical installations up to 1000 V.” Such information cannot be neglected, as well as the following: “Not suitable for extinguishing live electrical installations.”
Rescue services began to show up portable installations pulse fire extinguishing systems "Igla" and "Igla-2". Their use sharply reduces water consumption when extinguishing local fires, eliminating such an unpleasant procedure as pouring, in which something that has not had time to burn gets wet through and through. Working with Igla is especially effective in apartments where the use traditional ways fire extinguishing leads to large material losses not because of fire, but because of water.
In general, fire extinguishing is the job of professionals. Rescuers who have not completed a special training course and are not certified to work as part of a combat crew are left with two important areas: fire reconnaissance and human rescue.
The basic principles of fire reconnaissance are purposefulness, activity, timeliness and reliability of the data obtained. Reconnaissance is the most important type of support for firefighters. And very dangerous.
That part of the reconnaissance, which includes clarifying the internal structure of a burning object, the possible number of people inside, the presence and quantity of dangerous substances (all this is clarified through interviews with specialists, residents, workers and knowledgeable persons), requires speed, ingenuity and efficiency. But, as a rule, it does not pose any particular danger. This type of reconnaissance is possible for one person.
Much more dangerous and responsible is reconnaissance, which is carried out inside a burning object, in conditions of smoke, the release of toxic gases, darkness, the danger of collapse of structures and the occurrence of fire whirlwinds. Such reconnaissance is carried out in groups of two people, and in cases of using self-contained breathing apparatus - in groups of three people.
Any person can enter a burning object possible ways- through window openings, along ladders and assault ladders, using hydraulic lifts, ropes, free climbing on structures. This is when our ability to work safely at height can come in handy.
The task of reconnaissance is to determine the size and direction of the spread of the fire, the condition of the object (danger of collapse, explosion, etc.) and, most importantly, whether there are people blocked by the fire or injured by the fire. This leads to the continuation of the scout’s actions: to find ways to save people and determine methods of evacuation.
Scouts should always have flashlights, ropes, crowbars or hatchets for opening doors, and self-contained breathing apparatus at the ready.
If for closed door and something is burning with the partition - and this can be determined by streams of smoke from under the door, cracking paint, a burning smell, a heated door or partition, a change in the color of the paint or plaster - then you need to open this door very carefully while being under the protection of the partition or panel doors (if the door opens in your direction), since the influx of fresh air to the source of a possible fire can cause a sharp increase in the flame - a fire whirlwind, the culprit of severe burns and the death of many firefighters.
When entering a room, you need to leave the door behind you, and when leaving, close it. And be sure to try to remember your path. If along the way there are local sources of ignition that pose a danger of fire spread or threaten people, they should be extinguished immediately - this is where the portable “Igla” comes in handy.
In dark or smoky rooms, where flashlights are ineffective, you need to move around the perimeter, along the right wall, without losing contact with it. This reduces the risk of getting lost in passages, branches and winding corridors. If smoke spreads across the floor, you need to move at full height. If smoke rushes upward, you need to move bent over, and sometimes even crawl. The group moves one at a time, without leaving each other. At feeling unwell at least one scout, the group stops reconnaissance, helps a comrade get out Fresh air and helps him.
Victims found during reconnaissance must immediately begin to evacuate, requesting help by radio. Moreover, you need to check all the premises, not trusting the information of strangers that there are no people in the room or cannot be. They stop checking the premises only after personally verifying that there are really no people in the room who need help. A useful observation is made by the famous survivalist Jacek Palkiewicz: “It should be remembered that children, frightened by a fire, can hide in the most secluded places, for example under the bed, and almost always do not respond to unfamiliar voices.”
Rescue operations are carried out simultaneously with fire extinguishing. This relieves the burden on firefighters and creates a field of activity for rescuers. If joint actions are insufficient or ineffective, all firefighters are involved in rescuing people, using all available ways and means to evacuate people.
The rescue procedure is determined depending on the degree of threat from fire, smoke, explosion, or collapse. Children are rescued first, then the sick, the elderly and women. Ways to save people include:
· independent exit of people along the routes indicated to them;
· removal of people accompanied by firefighters or rescuers;
· removal of children and persons unable to move independently;
· evacuation of people using retractable and ladders, lifts, rescue hoses, slip-evacuators, ropes.
Particular attention is paid to those people who are afraid of evacuating from a height, are in an excited state, and lose their composure. In these cases, rescuers carry out evacuation with escort and arranging additional insurance. Not least important is the behavior of the rescuers themselves: calmness, confidence and goodwill will help relieve stress and take control of the situation.
It is especially difficult to organize rescue operations in places where there are large concentrations of people - in discos, theaters, hospitals, kindergartens, etc. It is true that the primary responsibility for the evacuation of people in these institutions lies with their management, but one should not overly expect that this will be:
· carried out in a qualified manner;
· in a timely manner;
· don't panic;
· no casualties;
carried out at all.
The initiative to prevent panic and organized evacuation should be in the hands of rescuers until the last person is removed from the danger zone. Rescuers and firefighters are placed along the evacuation route to regulate the flow of people, curb panic, and help those in need.
In hospitals, schools, and kindergartens, evacuation is carried out together with service personnel. The priority, order and methods of evacuation are determined by doctors and educators. During the cold season, special care must be taken to ensure that children and the sick are dressed or wrapped in blankets.
In all cases when rescue operations are underway during a fire, you should call an ambulance.
Most often, rescuers are called upon to extinguish forest fires. Here, the forces of professional firefighters alone are clearly not enough. Therefore, our qualified assistance comes in handy here.
The rarest case is a forest fire caused by lightning. In this case, several unfavorable factors must overlap each other at once: prolonged drought, high temperature and low air humidity, lightning striking a tall dead tree, strong wind. It is clear that a forest fire caused by a thunderstorm is exotic. But a forest fire due to an anthropogenic (human) cause is an outrageously ordinary and sad event.
Forest fires are usually divided into grassroots, top And underground.
In a ground fire, the fire spreads through dry grass, fallen leaves, and undergrowth. At the beginning of summer, as a rule, such fires do not cause much harm, since the forest floor has not yet dried out enough. In the middle of summer or during a long drought, a ground fire damages the undergrowth and roots and causes much more damage.
A crown fire is much more dangerous due to the fact that the crowns and branches of trees ignite and the fire spreads from high speed, “jumps” from tree to tree, even remote from the burning massif. Heat fire forms its own ascending air currents, into which air is sucked from the periphery - a source of additional oxygen. The fire covers large areas and is very difficult to extinguish.
The food for underground fires is peat, which lies under the forest. The thickness of the peat layer can reach tens of meters, and the peat can smolder in the depths for years.
They try to surround ground fires and start extinguishing them from all sides at once. The edge of the fire is spilled with water, covered with branches, and covered with soil. Depending on the strength and direction of the wind, as well as depending on the type of tree, density of undergrowth, and air temperature, choose best option extinguishing tactics: from the front of the fire, from the rear, along the entire perimeter, or with a retreat to a new line and the creation of a fire protection zone.
The undergrowth in it is cut down, the pine needles, and the leaves are covered with earth. The loosened soil is moistened if possible. The main tools here are an ax and a shovel. Backpack portable sprayers are low-productive. Let us remember with a kind word “Igloo”.
Raised fires are much more difficult to extinguish. Of course, all of the listed methods of combating ground fires are not excluded, but for large crown fires, more effective measures are needed.
These methods include annealing. When annealing along the front of a crown fire, that is, from the direction where the wind blows and where the fire spreads, a strip 20-100 meters wide is burned. This method of stopping a fire requires special skill and careful observation, since here they stop fire with fire, which is far from safe.
The rate of crown fire spread decreases at night. That's why optimal time Late evening and early morning hours are the time to fight fire.
An underground fire is extinguished using large quantity water pumped into the fireplace. There is a special technique for this. Underground fires are delineated by ditches that are filled with water.
The work of rescuers at such fires usually comes down to helping fell trees. All trees adjacent to the ditches on the side of the fire fall with their tops towards the fire. In order to place trees with a branched crown or inclined in the other direction exactly in a given direction, guy ropes made from climbing ropes are used. Guys are attached to the tree as high as possible and, if there are no other trees or stumps in the direction of felling, the rope is pulled manually. In this case, the length of the rope must be at least one and a half times the height of the tree. Using a chainsaw, make a double cut (like a slice of watermelon) in the direction of the felling to a depth slightly less than half the diameter. Pull the guy on the opposite side and make one horizontal cut, located 10-20 cm higher than the previous one.
Of course, if you have a rope attachment point, you can use a chain hoist, which will be more reliable, but, unfortunately, this does not happen often.
Climbing crampons with horizontal front teeth are used for tree climbing. The belay is organized using a piece of the main rope, one end of which is attached to the ISS belt, the second is looped around the trunk with slack and secured to the ISS on the other side of the belt.
Each household electrical appliance is, at its core, a fairly simple piece of equipment. Without going into detail, the most common part that fails is the gearbox or engine. It is due to this that most professional builders prefer specifically power tools.
This is due to the fact that it doesn't need repairs very often, like other types of tools, however, due to its simplicity, its cost is much lower than its gasoline counterparts. Perhaps, in the case of the same saw, even a complete amateur can visually identify a broken chain or a faulty saw bar, so we’ll immediately start talking about identifying engine malfunctions and some repair principles.
If your faithful assistant does not turn on at all and also does not show other “signs of life,” then you will not be able to do without a multimeter. However, if there is no opportunity to purchase it, then it is quite possible to use an ordinary incandescent lamp for the same purpose. She can help bring your power tool back to life.
Preliminary preparation for repairs
Electrical tool repair It is recommended to start with advance preparation for it. It is easy to guess that the main preparatory step can be considered the removal of every external part that may interfere with the disassembly process. Upon completion of the preparatory stage, connect the instrument to the network and, using the test lamp mentioned above, “ring” each connection.
It would be superfluous to cover in detail the importance of observing safety precautions.
Diagnostic progress
If all conductive paths are functioning, this means that the most unpleasant thing has happened: the engine has failed. In the vast majority of cases, it has to be immediately replaced with a new one or a serviceable one, but used. However, to rule out all possibilities, you can try to remove it and conduct a full diagnosis.
It should be noted that only a highly qualified specialist in such a situation will can bring a power tool back to life. At the same time, repairing equipment by an uninformed person leads to very sad consequences.
If we touch on the issue of identifying faults in the mechanical part, then, as already mentioned, in most cases this can be done through the usual visual inspection. As a rule, the damaged part simply becomes deformed.
Bosch brand power tool repair is especially good in this regard. The convenience of its maintenance and repair lies in the fact that service centers brands, and just in retail trade You can always find almost any parts for it. This sets it apart from its competitors, who practically never have this.
Looking at the “insides” of a failed instrument, you can often notice that the collector has fallen into disrepair. Sometimes it may seem that there is simply no reason for such a serious breakdown. Often this outcome is caused by too much heat, which occurs due to sparking brushes. This often happens if there are any shaft defects. In addition to the brushes, due to the same faults their holders also become unusable. In this case, it is quite simple to establish the cause, since you are unlikely to need servicing of the power tool, since replacing the brushes with your own hands is not likely to be difficult.
If we touch on the issue of the engine, then, as a rule, the cause of breakdowns is various problems in the stator windings. Usually short circuits between them are detected, which almost certainly damage the power tool. Repair in such a situation will consist of replacing the motor, because rewinding it yourself is quite difficult.
How to properly operate a power tool
Now let's talk about how to use power tools correctly, so that it serves as long and efficiently as possible. To do this, we will consider the causes of standard breakdowns and methods of preventing them, we will deal with the factory warranty and other pressing issues.
Factory defects: a few words about the warranty
The more consumers use power tools, the more controversial situations arise when the tools fail.
However, there is no doubt that during the period warranty period full responsibility for the instrument is clearly borne by the manufacturer. IN Lately The number of citizens' appeals to courts at various levels has increased, where civil appeals about the inadequate policy of the ASC and dishonesty on the part of manufacturers are dealt with. It’s good that such a common phenomenon as artificially shortening the shelf life has not yet been observed in the field of tool manufacturing.
If the device fails during the warranty period, then in any case, repairs must be made without payment! However, there are a number of restrictions that users rarely take into account, but in vain, since they are aimed at ensuring that manufacturers are responsible only for the assembly of the tool and defects in materials - that is, for a manufacturing defect. Of course, none of them will give a guarantee for equipment and parts that wear out quickly:
- platforms;
- rods;
- belts;
- canvases.
A reasoned reason for refusal of repair and maintenance may be:
- use of inappropriate lubricant or lack thereof;
- evidence of self-repair (no seal);
- low quality fuel mixture;
- mechanical defects of the armature and stator windings;
- worn out fastening mechanisms;
- belt rupture;
- damaged suction fan;
- spindle deformation;
- traces of liquids;
- heavy pollution;
- used or damaged brushes;
- worn gears;
- rust.
In fairness, we emphasize that popular manufacturing companies strive to consider in favor of the consumer. Many remove factory defects free of charge, even if they appear after the warranty period has expired.
Well-known manufacturers provide a guarantee to repair damage regardless of where the tool was purchased. The explanation for this is that image losses turn out to be many times more significant than the momentary benefit from a false “non-warranty case”. In this regard, direct consumer surveys are conducted, hotlines are organized, and service centers are monitored in every way. However, creating precedents that encourage an irresponsible user to abuse the service is also unprofitable for them.
How to avoid repair refusal
Buy equipment from popular and trusted manufacturers, which provide this guarantee and have their own ASCs.
Long-term tool overload
There can be several reasons for overloading a power tool:
- use of a tool for purposes other than its intended purpose;
- excessive pressure on the tool (this leads to destruction of the body, failure of the mechanics and motor),
- deviations from the norm in electrical power indicators
The main sign of overload is excessive heating of the device. If the cause of overheating is not eliminated in time, the process of destruction of the insulation of the motor windings begins, which results in a short circuit between turns, and this, in turn, leads to irreversible failure of the power plant.
A drill is one of the popular power tools that are popular not only during construction and finishing works. Depending on the nature of use of the tool and its quality, such problems may occur. Negative consequences like a drill breaking down. To fix the situation, there is no need to buy new tool, since you can repair the drill yourself. What you need to know for this, as well as what breakdowns can occur on the drill, we will find out further.
An electric drill consists of a plastic body (sometimes metal), as well as a working area, presented in the form of a chuck for securing the corresponding attachments for performing various works. The body of an electric drill contains both electrical and mechanical parts.
The electrical part includes the following components:
- Electric motor alternating current two-phase.
- Contact brushes located in the brush holder.
- Power tool start button.
- Power cable.
- Speed regulator.
- Mechanism for switching the direction of rotation of the cartridge.
- Start capacitor.
The mechanical part is presented in the form of a gearbox and a bearing system. The main function of the gearbox (set of gears) is to transmit torque from the electric motor shaft to the tool chuck. IN impact drills and rotary hammers, the mechanical part is additionally represented by two pistons, as well as a ram and a striker. These elements allow you to turn on the impact mode, that is, the jackhammer function. The design of the tool is not at all complicated, so even an inexperienced specialist can fix any breakdowns that occur. Before you begin to repair the breakdown, you must find the cause, and for this you need to disassemble the tool.
Required tools and materials
To repair a drill yourself, you will need to use the following tools:
- screwdrivers to disassemble the tool;
- multimeter to determine electrical faults;
- sandpaper to clean oxidized contacts.
Depending on the cause of the breakdown, some materials will also be required. These include:
- gears;
- brushes;
- bearings;
- button.
In addition, if the tool has not been disassembled for a long time, then it is advisable to change the lubricant in the gearbox during disassembly. This will reduce the load on the electric motor and will also extend the life of the tool. Bearings also need lubrication, so regardless of the reasons for the malfunction of the tool, after eliminating them, you must definitely devote time to diagnostics.
Mechanical problems
Do-it-yourself drill repair begins with determining the causes of the tool malfunction. First you need to identify which part of the tool has failed: electrical or mechanical. As a rule, this is not difficult to do. The main mechanical problems include:
- Bearing failure.
- Gearbox failure.
- Gearbox failure.
Mechanical problems can be identified quite easily, since the sound of a running electric motor will be heard. If the gearbox or bearing is faulty, a characteristic sound will occur. If the cartridge is faulty, the master will not be able to clamp the working element in it.
- The bearings are faulty. Bearings can fail only if dust gets into the lubricant, or from excessive loads. If the bearing has not crumbled, then eliminating the damage will not be difficult. To do this, you need to disassemble the tool, wash the bearing with kerosene, and then fill it lubricant. After this, do not forget to replace the seals, since, most likely, it was because of them that dust got inside the tool. It is better to lubricate bearings with special lubricants for high-speed devices.
- Problems with the gearbox can only be eliminated by replacing the gears. As a rule, the entire mechanism is replaced, since it is almost impossible to find any spare part separately. You can purchase the gearbox for the drill itself if your drill has famous name. If the drill is unknown or made in China, then it is almost impossible to find any spare parts for it.
- Cartridge failure. If a key chuck is installed on the tool, then such products rarely fail. But if this happens, then it is necessary to replace the entire device. In some cases, one jaw may become jammed in the chuck, so to eliminate the problem, the product must be disassembled and cleaned. Keyless chucks They fail more often, so they should be replaced with a new one after a breakdown or when the clamp becomes loose.
Often, in the mechanical part, the bearings or gearbox system, or less often the cartridge, fail. To eliminate a chuck malfunction, there is no need to disassemble the tool. In any case, repairing the mechanics of a drill is much cheaper than resorting to purchasing a new tool.
The most common electrical faults
Electrical malfunctions are determined quite simply, since when you press the start button, the tool will not emit characteristic features life. To repair a drill with electrical faults, you must first find the specific cause of the breakdown. TO frequent malfunctions electrical parts include:
A drill belongs to the category of those tools that are quite easy to self-repair. After identifying the cause of the malfunction, it will not be difficult to fix the breakdown or replace the failed unit. Be sure to remember that the tool may still be under warranty, so do not rush to disassemble it.
Chipping cutting elements tool or its breakdown
The reasons leading to chipping and tool breakage are often the same and can therefore be considered together.
1. One of the main reasons for these problems is the increased fragility of the tool material. In relation to mineral ceramics and hard alloys, this feature has already been noted more than once. High speed steels have sufficient strength, but in practice one often has to deal with increased fragility of high-speed cutting tools, which is caused by poor quality of the material (presence of foreign inclusions, large carbide heterogeneity, etc.), improper forging of workpieces or incorrect heat treatment; in the latter case, the tool’s hardness is often found to be excessively high. It must be remembered that the hardness of a tool that has protruding areas of small thickness on the cutting blade that are prone to chipping should be somewhat lower than the hardness of simple-shaped roughing tools.
Finally, it should be taken into account that cyanidation, which helps to increase the durability of the tool, is associated with a slight increase in its fragility. Therefore, as already indicated in Chap. I, cyanidation of instruments with a small cross-section often has to be abandoned.
2. Overload cutting tool when the shear cross-section is too large, when the strength of the part material is increased, or when the tool is excessively dull, i.e., working in conditions where the magnitude of the cutting forces expended exceeds those for which the tool design is designed. When milling, tool overload often occurs due to excessive runout of the cutter teeth, abrupt approach of the part to the cutter (before turning on the automatic feed), and large unevenness of milling due to an insufficient number of cutter teeth.
3. Weakening of the cutting part of the tool as a result of improper sharpening (with too large front or back angles).
4. Turning a tool with a rotary working motion (cutters, drills, countersinks) due to poor fit between the cones of the tool shank (or mandrel) and the hole in the machine spindle causes breakdowns, as it leads to a sharp increase in the load on the cutting blades (if the automatic feed does not stop) .
5. Chip pinching and poor chip removal are one of the most common reasons breakdowns of multi-blade tools.
When working with simple through cutters, the chips flow freely. When working with cutters, broaches, taps, drills for drilling deep holes, all the chips removed must be placed in the grooves between the teeth of the tool, and if the volume of these grooves is insufficient (which especially often happens when processing very viscous metals, for example mild steel, aluminum, which give drain chips occupying a large volume), then they become clogged with chips and the tool breaks.
A typical example is the frequent breakage of small taps. Often taps, regardless of their diameter, have four grooves. With a small tap diameter (4-6 mm), this results in a very small groove volume, and the tap core, in turn, is also weakened. Therefore, for small taps the number of grooves should be reduced, taking two grooves for a thread diameter up to 8 mm, three grooves from 8 to 14 mm, and four or more grooves above 14 mm.
Mills that remove large chips from steel parts must have a sufficient volume of cavities between the teeth; If regrinding of cutters is carried out only on the rear surfaces, then it is necessary to deepen the grooves from time to time.
The length of the working part of the drill, on which there are helical grooves, must exceed the drilling depth. If the walls of the hole cover the grooves and do not provide an outlet for chips, then breakage of the drill is inevitable.
6. Unsatisfactory quality of the cooling lubricant in terms of lubrication of the working surfaces of the tool can lead to chipping. With high lubricating and “cutting” properties of the liquid, cutting forces are significantly reduced; if the liquid does not get onto the cutting surfaces at all, then the tool jams, chips and breaks.
7. Tool chipping and breakage may be caused by causes beyond the control of the tools themselves and may be due to faulty machine tools or fixtures.
Examples include: large slack in the feed mechanism drilling machine, as a result of which the drill is fed unevenly, jerkily and is heavily overloaded (especially when exiting the hole); development of guides or nuts lead screw milling machine; distortions of the part in the reaming device, as a result of which the reamer does not fall into the pre-drilled hole; strong vibrations of tools and parts, etc.
Particularly often, instruments equipped with plates made of hard alloys or mineral alkali, which are characterized by increased fragility and require great care in operation, become chipped and broken.
In addition to the reasons discussed above, the following circumstances may also lead to chipping and breakage of such instruments.
8. The presence of small cracks on the plates (sometimes in the form of a barely noticeable “mesh”), which appear as a result of sudden cooling of the tool after soldering the plates or incorrect sharpening technology (use of abrasives with inappropriate characteristics; excessive rotation speed grinding wheel or its movements along the surface being sharpened; sharp cooling of the carbide during sharpening; using a “greasy” grinding wheel; too large contact surface of the grinding wheel with the plate being sharpened), and also due to unsatisfactory quality of manufacture of the hard alloy itself. It is characteristic that cracks caused by sudden cooling or improper sharpening usually have the appearance of straight or broken lines or a broken mesh, while defects in the carbide can lead to the appearance of cracks in the form of smooth curved lines of considerable width.
Interruptions in the supply of coolant lead to cracking and subsequent chipping of the plates, since in this case the heated hard alloy is subjected to sudden cooling. It is necessary to ensure that the coolant flows in sufficient quantities and that the falling chips do not block the carbide plate. If it is not possible to meet these requirements, then it is better to work without cooling at all.
When high-speed milling, coolant should not be used, since alternation of heating and sudden cooling is inevitable.
Measures to prevent cracking of carbide plates are described in the chapters above.
9. Chipping of plates made of carbide alloy and mineral ceramics can be caused by non-compliance with those special requirements for the geometry of the tool, which help to increase the strength of the cutting blade: the absence of chamfers with a negative rake angle or their insignificant width, insufficient angle of inclination of the main cutting blade (especially when working with impacts ), too large back angles, lack of transition cutting blades (for cutters).
10. If the dimensions of the chip-curling threshold are incorrect—its width is too small and great depth- steel shavings get stuck in it and this causes chipping of the cutting blades.
11. Chipping and breakage of carbide and mineral ceramic plates are often caused by non-compliance elementary rules operation of tools - careless handling of cutters, stopping the spindle rotation when the automatic feeding etc. It is unacceptable to move a non-rotating cutter along an already machined surface when retracting after a working pass.
When working with cutters with mineral-ceramic plates, chipping often occurs due to impacts during cutting. Therefore, you should first trim the end of the workpiece or chamfer it, and also perform plunging with manual feed. It is not advisable to use such cutters for processing short parts with a large number of radial cuts and exits.
Carbide and mineral-ceramic instruments should be stored and transported in conditions that prevent impacts on the blades.
12. Mineral-ceramic and carbide plates are especially likely to chip when working with vibrations. The causes of vibrations and ways to eliminate them will be discussed below.
13. If chipping and breakage of plates cannot be eliminated by any means, then you should try to use a more durable hard alloy; in some cases, it turns out to be advisable to replace the carbide with high-speed steel.
All household electrical appliances are inherently quite simple equipment. Without going into detail, most often the engine, gearbox or working element fails. It is due to this that many professional builders They prefer power tools. It does not require repairs as often, but due to its simplicity it costs much less than its gasoline counterparts.
We think that in the case of the same saw, even a complete layman can visually determine a breakdown of the saw bar or a broken chain, and therefore we’ll immediately talk about some principles of repair and determination
So, if your faithful assistant does not turn on at all and does not show other “signs of life,” then you will not be able to do without a multimeter, but if you cannot buy one, it is quite possible to use an ordinary incandescent lamp for the same purpose. It will help bring your power tool back to life. Repairs should begin with preliminary preparation to him.
You can guess that the most important preparatory stage you should consider removing all external parts that could interfere with the disassembly process. After this, we turn on the instrument into the network, and, using the test lamp we mentioned, we “ring” all connections. It goes without saying how important safety precautions are.
If all conductive paths are working, then the most unpleasant thing has happened: the engine has flown. In most cases it has to be changed, but you can try to remove it and carry out diagnostics. It should be noted that only a specialist highly qualified in such a situation will be able to bring the power tool back to life. Repairing it by an ignorant person will lead to the most dire consequences.
If we talk about diagnosing mechanical faults, we have already said that in most cases this can be done through a simple visual inspection. Most often, the damaged part is simply replaced. Repair is especially good in this regard. Bosch power tools. The fact is that in its service centers, and simply in retail trade, you can find almost all the parts for it, which is practically not the case with competitors.
When examining the “insides” of the damaged instrument, you can often see a collector that has become unusable. It may often seem that there are simply no reasons for such a serious breakdown.
Most often, this outcome is caused by extremely strong heating that occurs when the brushes spark. By the way, very often they begin to spark due to existing shaft defects. In addition to brushes, due to these same faults their holders fail. Determining the cause in this case is quite simple, so you are unlikely to need service repair of power tools in Moscow, since replacing the brushes yourself is not so difficult.
If we talk about the engine, then most often the cause of breakdowns is some kind of malfunction in the stator windings. Short circuits between them often occur, which almost certainly damage the power tool. Repair in this case consists of