Types, purpose and designations of bearings

Bearing designations today are extremely actively used in various spheres of modern production, because this is an absolutely irreplaceable detail, which is now used in the majority of the most diverse mechanisms and assemblies. To date, they are universally used in everything from miniature household appliances and ending with the huge machinery used in industrial production equipment.

No modern enterprise, industrial complex or production association can not help using certain bearing designations and the products themselves, which at the same time have a limited lifespan, and the only reason for this phenomenon is that they simply do not have any specific alternative. In this regard, the continuity and activity of various enterprises, and therefore their economic efficiency, directly depend on how timely they are delivered and put such products in case of their wear and tear.

History

Not everyone correctly understands the old saying that everything new is simply a long-forgotten old. This immortal statement is quite suitable for almost any modern technology, and in particular, it concerns the bearing, in spite of the fact that since the time when the first designations of bearings have appeared, it has already passed a huge evolutionary path, and initially such products did not look much like They are represented by many today.

If you plunge deeply into history, it's worth starting from 3500 BC, when the inhabitants of Ancient Egypt used, although primitive enough, but at the same time for their time extremely effective bearing bearings, in which, however, on that The moment balls were not used yet. Around 700 BC. Celts already knew perfectly well and actively used products, which nowadays designation of bearings are referred to as cylindrical rolling devices.

The next step is 330 BC, in which one of the most famous engineers of Ancient Greece, Dyad was able to create a full siege machine, one of the main elements of which were fairly primitive bearings. This machine was a full-fledged massive ram, which could easily move with roller guides. This is how in practice the principle has been shown, which carries in itself any ball bearing of rolling, that is, friction of sliding has been replaced by friction of rolling, thanks to which the machine was able to easily perform the tasks assigned to it, using much less force.

In 1490, Leonardo da Vinci invented the world's first rolling bearing design. It is worth noting that this invention caused a real sensation in the circles of experts, but in fact, over time, many realized that at that time such a product simply was not practical use.

In 1794 there was the first patenting of the rolling bearing, which is an analogue of the modern device. Unfortunately, the use of this sample in practice was not destined to take place either, because in order to fully implement this idea, it was necessary to have other technical possibilities, since the use of manual polishing did not allow achieving the corresponding results.

In 1839, a scientist from America named Isaac Babbitt invents a specialized alloy, with the help of which the balls were started, which further included a full-fledged roller bearing. This alloy included copper, antimony, lead and tin in its composition.

Then there was a real breakthrough in the field of technically sound bearing designs, and most of them, of course, were patented. In 1853, Phillip Moritz Fisher designed the first ever pedal bicycle, the mechanisms of which contained a specialized roller bearing.

The last really significant for launching the widespread distribution and use of such products was the event that Friedrich Fischer created in 1883 a machine with which the grinding of balls made of hardened steel was carried out. At the same time, it should be noted that this machine allowed to obtain such a high level of grinding, which previously was simply unattainable. Due to the creation of this machine appeared the world-famous Schweinfurt bearing plant, and in the future similar products have already begun to be used almost everywhere.

Since then, the perfection of technologies has been continuously carried out at a tremendous pace - more precise equipment has been purchased, the bearing number has begun to be inscribed, and certain production standards have been developed. In the end, we see a product familiar to many, without which it is almost impossible to imagine modern production today.

The most popular and popular in our time can be called sliding and rolling bearings , so in this article we will discuss their use.

Rolling bearings

The main principle of this bearing is the use of rolling friction . Such a product has a design that is composed of two metal rings with a groove between which rollers, needles or balls are placed, fixed inside the separator located between the rings. It is worth noting that you can find more than one bearing number, which provides the possibility of the absence of a separator in its design.

What are their differences?

Modern rolling bearings are classified according to several basic characteristics:

• The type of bodies that are used to ensure the same rolling - roller / needle or ball bearing;
• The type of possible load is linear, thrust, radial, radial-thrust and ball screw drives.
• The total number of elements used is from single-row to multi-row.
• The possibility of providing compensation for the fact that there is no coaxiality of the sleeve and shaft in the structure is self-installing and self-aligning.

Benefits

There are a number of advantages that such bearings are advantageous for. GOST establishes sufficiently stringent production standards for such products, the compliance of which must provide the following advantages:

• The extremely high KDA, which is achieved by achieving minimum losses due to friction.
• At times, and in some cases even tens of times the reduced friction torque compared to the bearings.
• The complete absence of any need for the use of expensive non-ferrous metals, without which slip bearings could not be used effectively, which has a very positive effect on the initial cost price and, consequently, the final price that such bearings have. GOST at the same time clearly enough indicates the requirements for their production, so you do not have to worry about the fact that for less money you will not get a better product.
• Possibility of manufacturing bearings of practically any dimensions you are interested in towards the axis, due to which the range of their application is significantly extended.
• Excellent operating parameters, as well as complete maintenance-free operation in combination with relative simplicity of replacement.
• Extremely low lubricant consumption.
• Quite low cost, which is a consequence of too large a mass production of such products, as well as the number of materials used.
• Quite a high degree of interchangeability, which also positively affects the overall simplicity and speed of repair of various equipment and machines.

Minuses

At the same time, one can not help saying that even the designation of imported bearings of this type provides for certain disadvantages, namely:

• Relatively small range of application. In the majority of cases, if you disassemble the designations of bearings, the interpretation of their characteristics clearly indicates that they are completely unsuitable for use in equipment operating at ultra-high speeds and with large vibrational and shock loads, since all these are not subject to such products.
• A fairly large mass and dimensions in the radial direction.
• Absence of the possibility of creating completely silent bearings because of the shape errors.
• Quite complex installation of various bearing units.
• We must be extremely careful to ensure that such products are installed as precisely as possible, as indicated by the designations of the bearings. Deciphering the main parameters and practical examples of their use suggests that even small inaccuracies can ultimately lead to the disabling of the entire assembly.
• In the process of manufacturing small batches of bearings with non-standard sizes their cost increases quite strongly.

Plain bearings

The designation of bearings according to GOST indicates that the sliding devices are a housing with a hole inside which there is a lubricating device and a special bushing made of antifriction material. Rotation of the shaft is due to the gap provided between it and the hole. It is worth noting the fact that the calculation of this gap is given special attention, since otherwise it will not be possible to ensure the really effective operation of this product. That is why the designation of SKF bearings and the logo of other major world manufacturers, as a minimum, makes it possible to be sure that their characteristics correspond to high-level products and will not give any doubt about the effectiveness of the products used.

Slip friction in similar products is divided into several main categories:

• Boundary . The lubricant covers the product with a thin film, while the bearing with the shaft touches the full or just touches the sections over a long distance.
• The liquid . Due to the use of a layer of liquid lubricant, direct continuous contact between the surfaces of the bearing and the shaft is excluded. Such contact can either be completely absent or be unstable in certain areas.
• Gas . Due to the presence of gas interlayer between the product and the shaft, the possibility of their direct contact is completely excluded.
• The dry one . Lubrication is not used in principle, and the shafts at the same time completely cover the diameters of bearings or they lie on sections of considerable length.

Depending on the type of product used, plastic, liquid, gaseous or solid lubricant may be used.

Classification

Classification of such products is carried out depending on the following features:

• The shape of the hole is single-surface or multi-surface; With a displaced center or without displacement; With a displaced surface or without displacement.
• The directions of the arising load are axial, radial or radial-thrust.
• The number of oil valves used is one or two or more.
• Design - detachable, integral or built-in.
• Adjustability - the possibility of adjustment or its absence.

Benefits

If we talk about the main advantages of such products, there are several of them:

• Extremely wide range of possible applications due to the fact that the bearings can operate normally even at large shock and vibration loads or at a sufficiently high speed.
• A sufficiently high degree of economy, if a shaft with a large diameter is used.
• Can be used as a split bearing.
• The possibility of adjusting the clearance, so that the shaft axis can be installed with the utmost precision.

disadvantages

In this case, of course, these products have some disadvantages:

• Unlike the designation of rolling bearings, the efficiency is not the highest, since there are quite significant friction losses.
• There is no way to ensure normal operation without regular lubrication.
• Uneven wear of the trunnion and the product itself.
• High enough cost due to the need for regular use of non-ferrous metals in the production process.
• Huge labor input in manufacturing.

Marking

All products that are manufactured on the territory of Russia, must necessarily be labeled by manufacturers, and the designation of bearings according to GOST is established. The marking of any modern bearing includes seven digits of the main designation, as well as several additional signs that are located to the left or to the right of the main designation. At the same time, it is worth noting the fact that, from the main, the additional marking on the left should always be separated by a hyphen, while on the right is the letter designation of the bearings. In this case, the signs in any case should be read only from left to right.

Left signs, which includes the designation of bearings in the drawing, contain the following:

• Moment of friction;
• Product category;
• Accuracy class ;
• Radial clearance group.

On the right, the following is indicated:

• Constructive changes;
• Material used in the process of manufacturing these parts;
• lubricant;
• Tempering temperature;
• Basic requirements for a certain level of vibration.

Diameters

If we are talking about the designation of diameters, the size of which is no more than 10 mm, then the value of the nominal diameter is considered, and the only exception here is bearings having holes with a diameter in the range 0.6-2.5 mm, the designation of which is carried out in fractional numbers. In other situations, if the diameter has a fractional value, then the notation will have a rounded to the whole, while the second place in the designation of this product is the figure "5".

Bearings with a hole diameter of 10, 12, 15 or 17 mm have 00, 01, 02 or 03, respectively, in their diameter designation. If this hole, the size of which is in the range from 10 to 19 mm, but is not included in the list listed above, then the product is indicated by the nearest number of the above, and in the third position of the marking the figure "9" is put.

If the diameter of the hole is 22, 28, 32 or 500 mm, then fractional values are indicated to it. For example, a product with a diameter of 22 mm can have the designation "602/22".

If the diameter of the hole has an integer or fractional number that is not a multiple of five, then in this case they are denoted as rounded to the whole number of quotients from the division of the present diameter by 5. The main designation of such products includes the third digit "9".

The internal diameter of the bearings, having an opening of more than 500 mm, has a designation that fully coincides with the indicated diameter of the hole, calculated in millimeters.

Among other things, the dimensional bearing series is indicated, which includes a combination of series of widths and diameters to determine the exact dimensions.