Bearing designations today are extremely actively used in various areas of modern production, because this is an absolutely irreplaceable part, which today is used in the vast majority of a wide variety of mechanisms and assemblies. Today, they are used everywhere in everything from miniature household appliances to huge mechanisms used in industrial production equipment.
Not a single modern enterprise, industrial complex, or production association can not use one or another designation of bearings and the products themselves, which at the same time have a limited service life, and the only reason for this phenomenon is that they simply do not have any specific alternative. In this regard, the uninterrupted operation and activity of various enterprises, and hence their economic efficiency, directly depend on how timely such products are delivered and delivered in case of wear.
History
Not everyone correctly understands the old adage saying that everything new is just a long forgotten old. This immortal statement is quite suitable for almost any modern technology, and in particular, it concerns the bearing, despite the fact that since the time the first designation of bearings appeared, a huge evolutionary path has already passed, and initially such products looked far from what Today they are represented by many.
If you plunge deeply into history, then it’s worth starting from 3500 BC, when the inhabitants of Ancient Egypt used, although quite primitive, but at the same time extremely effective support bearings, in which, however, moment no balls were used. Around the year 700 BC The Celts already knew very well and quite actively used products, which in our time are used to designate bearings 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-fledged siege machine, one of the main elements of which were fairly primitive bearings. This machine was a full-fledged massive ram, which could easily be moved using roller guides. That’s how the principle that any ball bearing of rolling bearings carries in itself was shown in practice, that is, sliding friction was replaced by rolling friction, 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 drawing of a rolling bearing. It is worth noting the fact 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 did not find practical application.
In 1794, the first patenting of a rolling bearing, which is an analogue of a modern device, took place. Unfortunately, the use of this sample in practice was also not destined to take place, because in order to fully realize this idea, it was necessary to have other technical capabilities, since the use of manual polishing did not allow achieving the corresponding results.
In 1839, a scientist from America named Isaac Babbitt invented a specialized alloy, with the help of which balls began to be produced, which further included a full-fledged roller bearing. This alloy included copper, antimony, lead and tin.
Then there was a real breakthrough in the field of technically sound bearing designs, and the vast majority of them, of course, were patented. In 1853, Phillip Moritz Fischer constructed the first pedal bike in history, the mechanisms of which contained a specialized roller bearing.
The last truly significant event for launching the widespread distribution and use of such products was the fact that Friedrich Fischer created in 1883 a machine with which grinding balls made of hardened steel were carried out. It is worth noting that this machine made it possible to obtain such a high level of grinding, which previously was simply unattainable. Due to the creation of this machine, the world-famous Schweinfurt Bearing Plant appeared, and in the future such products have already begun to be used almost everywhere.
Since then, technology has been continuously improved at a tremendous pace - more accurate equipment was purchased, the bearing number began to be affixed, and certain production standards were developed. In the end, we see products familiar to many, without which today it is almost impossible to imagine modern production.
The most popular and popular in our time can be called sliding and rolling bearings, so in this article we will analyze their use.
Rolling bearings
The basic principle of this bearing is the use of rolling friction. Such a product has a structure, which is composed of two metal rings with a groove, between which rollers, needles or balls are placed, which are fixed inside a separator placed between the rings. It is worth noting that you can find more than one bearing number, providing for the possibility of the absence of a separator in its design.
What are their differences?
Modern rolling bearings are usually classified according to several main features:
- 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, angular contact and ball screw gears.
- The total number of elements used is from single-row to multi-row.
- The ability to provide compensation for the fact that there is no alignment between the sleeve and the shaft — non-self-aligning and self-aligning.
Benefits
There are a number of advantages that distinguish these bearings. GOST establishes fairly stringent production standards for such products, compliance with which should provide the following advantages:
- Extremely high KDA, which is ensured by achieving minimal losses due to friction.
- At times, and in some cases even tens of times, a reduced moment of friction compared to plain bearings.
- The complete absence of any need for the use of expensive non-ferrous metals, without which plain bearings could not be effectively used, which has a very positive effect on the initial cost and, consequently, the final price such bearings have. At the same time, GOST quite clearly indicates the requirements for their production, so there is no need to worry about the fact that for less money you will get a not so high-quality product.
- The ability to manufacture bearings of almost any size you are interested in towards the axis, so that their range of application is greatly expanded.
- Excellent operational parameters, as well as complete unpretentiousness in maintenance combined with relative ease of replacement.
- Extremely low lubricant consumption.
- Fairly low cost, which is a consequence of too large mass production of such products, as well as the amount of materials used.
- A rather high degree of interchangeability, which also positively affects the overall simplicity and the magnitude of the speed of repair of various equipment and machines.
Minuses
At the same time, one cannot fail to say that even the designation of imported bearings of this type provides for the presence of certain disadvantages, namely:
- Relatively small range of application. In the predominant majority of cases, if we take the bearing designations apart, a breakdown of their characteristics clearly indicates their complete unsuitability for use in equipment operating at ultrahigh speeds and with high vibration and shock loads, since all this is not subject to such products.
- Quite a large mass and dimensions in the radial direction.
- The inability to create completely silent bearings due to shape errors.
- Quite complicated installation of all kinds of bearing units.
- Care must be taken to ensure that such products are installed as accurately as possible, as indicated by the bearing designations. Deciphering the main parameters and practical examples of their use suggests that even small inaccuracies can ultimately lead to the failure of the entire node.
- 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 of which there is a lubricating device and a specialized sleeve made of antifriction material. The 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 simply not be possible to ensure truly effective operation of this product. That is why the designation of SKF bearings and the logo of other major world manufacturers, at a minimum, allows us to be sure that their characteristics correspond to high-level products and will not allow to doubt the effectiveness of the products used.
Sliding friction in such products is divided into several main categories:
- Boundary . The lubricant covers the product with a thin film, while the bearing with the shaft is in full contact or simply affects areas over a long distance.
- Liquid . Through the use of a layer of sufficiently fluid lubricant, direct continuous contact between the bearing surfaces and the shaft is eliminated. Such contact may either be completely absent or may be unstable in certain areas.
- Gas . Due to the presence of a gas layer between the product and the shaft, the possibility of their direct contact is completely excluded.
- Dry . Lubrication is not used in principle, while the shafts completely cover the diameters of the bearings, or they fall on areas of considerable length.
Depending on the type of product used, a plastic, liquid, gaseous or solid lubricant may be used.
Classification
The classification of such products is carried out depending on the following features:
- Hole shape - single-surface or multi-surface; with a displaced center or without displacement; with a displaced surface or without displacement.
- Directions of the arising load - axial, radial or angular contact.
- The number of oil valves used is one or two or more.
- Design - detachable, one-piece 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 high shock and vibration loads or at a sufficiently high speed.
- Fairly high degree of efficiency if a shaft with a large diameter is used.
- Possibility of use in the form of a split bearing.
- The ability to provide clearance adjustment, so that the shaft axis can be set with extreme precision.
disadvantages
At the same time, of course, such products have some disadvantages:
- In contrast to the designation of rolling bearings, this is not the highest efficiency, since there are quite significant friction losses.
- There is no way to ensure normal operation without regular lubrication.
- Uneven wear on the trunnion and the product itself.
- Fairly high cost due to the need for regular use of non-ferrous metals in the manufacturing process.
- Huge laboriousness in manufacturing.
Marking
All products that are manufactured on the territory of Russia must be marked by manufacturers without fail, 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 characters that are located to the left or to the right of the main designation. It is worth noting that the additional marking on the left should always be separated by a hyphen from the main one, while the letter designation of the bearings is on the right. In this case, the characters in any case should be read only from left to right.
The left signs, which includes the designation of the bearings in the drawing, contain the following:
- friction moment;
- product category;
- accuracy class;
- radial clearance group.
The following is indicated on the right:
- design changes;
- material used in the manufacturing process of these parts;
- lubricant;
- tempering temperature;
- basic requirements for ensuring a certain level of vibration.
Diameters
If we are talking about the designation of diameters whose size is not more than 10 mm, then the value of the nominal diameter is considered, and the only exception here are bearings having holes with a diameter in the range of 0.6-2.5 mm, the designation of which is carried out by a fractional number. In other situations, if the diameter is fractional, then the designation will be rounded to the nearest whole, while the second place in the designation of this product is put the number "5".
Bearings, the bore diameter of which is 10, 12, 15 or 17 mm, in their diameter designation have the numbers 00, 01, 02 or 03, respectively. If this hole, the size of which is in the range from 10 to 19 mm, but is not included in the above list, then the product is indicated by the closest number from the above, and in the third position of the marking is put the number "9".
If the diameter of the hole is 22, 28, 32 or 500 mm, then in this case they indicate fractional values. For example, a product with a diameter of 22 mm may 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 they are indicated as rounded to the integer quotient of dividing the present diameter by 5. Moreover, the main designation of such products includes the number “9” in third place.
The inner diameter of the bearings, having an opening of more than 500 mm, has a designation that fully coincides with the specified value of the diameter of the hole, calculated in millimeters.
Among other things, the dimensional series of the bearing is indicated, which includes a combination of a series of widths and diameters to determine the exact dimensions.