Types, purpose and designations of bearings

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Designations of bearings today are extremely actively used in various areas of modern production, because it is an absolutely indispensable part that is used today in the predominant majority of a wide variety of mechanisms and assemblies. Today, they are ubiquitous in everything from miniature household appliances to huge machines used in industrial manufacturing equipment.

Not a single modern enterprise, industrial complex or production association can not use certain designations 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 - a particular alternative. In this regard, the continuity and activity of the work of various enterprises, and hence their economic efficiency, directly depend on how timely such products are delivered and put in case of wear.

History

Not everyone understands the old adage that everything is newis simply a long-forgotten old. This immortal statement is quite suitable for almost any modern technology, and in particular, this applies to the bearing, despite the fact that since the first bearing designations appeared, a huge evolutionary path has already passed, and initially such products looked far from the same as they are represented by many today.

If you plunge into history very deeply, then you should start from 3500 BC, when the inhabitants of Ancient Egypt used, albeit quite primitive, but at the same time extremely effective thrust bearings, however, at that time balls had not yet been used. Around 700 B. C. the Celts already knew very well and quite actively used products that in our time are referred to as bearing designations as cylindrical rolling devices.

The next step is 330 BC, in which one of the most famous engineers of Ancient Greece, Diad, was able to create a full-fledged siege machine, one of the main elements of which were rather primitive bearings. This machine was a full-fledged massive ram, which could easily move with the help of roller guides. This is how the principle was shown in practice, which carries any ball bearing, 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 specialists, but in fact, over time, many realized that at that time there was simply no practical application for such a product.

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 implement this idea, it was necessary to have other technical capabilities, since the use of manual polishing did not allow achieving the appropriate results.

In 1839, an American scientist named Isaac Babbitt invents a specialized alloy with which balls began to be produced, which later included a full-fledged rolling bearing. This alloy included copper, antimony, lead and tin.

Next there was a real breakthrough in technically sound bearing designs, and the vast majority of them, of course, were patented. In 1853, Phillip Moritz Fischer designs the first pedal bicycle in history, the mechanisms of which contained a specialized roller bearing.

The last really 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 was carried out. At the same time, it is worth noting the fact that this machineallowed to obtain such a high level of grinding, which was simply unattainable before. Due to the creation of this machine, the world-famous Scheinfurt bearing factory appeared, and in the future, similar 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, bearing numbers began to be affixed, and certain production standards were 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 plain and rolling bearings, so in this article we will analyze their use.

Rolling bearings

The basic principle of this bearing is the application of rolling friction force. Such a product has a design, which is made up of two metal rings with a groove, between which rollers, needles or balls are placed, which are fixed inside the 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 cage in its design.

What are their differences?

Modern rolling bearings are usually classified according to several main features:

• Type of bodies that are used to ensure the same rolling - roller / needle or ball bearing;
• Type of possible load –linear, thrust, radial, angular contact and ball screws.
• Total number of elements used, from single-row to multi-row.
• Possibility to provide compensation for the lack of alignment of the sleeve and shaft in the design - non-self-aligning and self-aligning.

Benefits

There are a number of advantages that distinguish these bearings. GOST establishes fairly strict standards for the production of such products, compliance with which should provide the following benefits:

• Ultimately high CDA achieved by achieving minimum friction losses.
• At times, and in some cases even tens of times reduced friction torque 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, accordingly, the final price that such bearings have. At the same time, GOST clearly indicates the requirements for their production, so you don’t have to worry that for less money you will get a less high-quality product.
• The ability to manufacture bearings of almost any dimensions you are interested in towards the axis, due to which the range of their application is significantly expanded.
• Excellent performance and low maintenance combined with relativeease of replacement.
• Ultimately low lubricant consumption.
• Relatively low cost, which is a consequence of too much mass production of such products, as well as the amount of materials used.
• A rather high degree of interchangeability, which also has a positive effect on the overall simplicity and speed of repair of various equipment and machines.

Cons

At the same time, one cannot but 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 overwhelming majority of cases, if we disassemble the designations of bearings, the decoding of their characteristics clearly indicates their complete unsuitability for use in equipment operating at ultra-high 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.
• Unable to create completely silent bearings due to shape error.
• Quite complicated installation of various bearing units.
• You need to be extremely careful to install such products as accurately as possible, as evidenced by the bearing designations. Deciphering the main parameters and practical examples of their use suggests that even small inaccuracies can eventually lead to the failure of the entire node.
• BIn the process of manufacturing small batches of bearings with non-standard sizes, their cost increases quite a lot.

Plain bearings

The designation of bearings according to GOST indicates that sliding devices are a housing with a hole, inside of which there is a lubricator and a specialized bushing made of anti-friction material. The rotation of the shaft is carried out due to the gap provided between it and the hole. It is worth noting the fact that special attention is paid to the calculation of this gap, since otherwise it simply will not be possible to ensure the really efficient operation of this product. That is why the designation of SKF bearings and the logos of other world's largest manufacturers, at least, allows you to be sure that their characteristics correspond to high-level products and will not let you 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 is in full contact with the shaft, or simply affects areas over a long distance.
• Liquid. Due to the application of a layer of sufficiently liquid lubricant, direct continuous contact of the surfaces of the bearing and shaft is eliminated. Such contact may either be completely absent or be intermittent in certain areas.
• Gas. Due to the presence of a gas layer between the product and the shaft,the possibility of their direct contact.
• Dry. Lubrication is not used in principle, while the shafts completely cover the diameters of the bearings or they lie on sections of considerable length.

Depending on the type of product used, grease, liquid, gaseous or solid lubricant can be used.

Classification

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

• Hole shape - single-surface or multi-surface; with or without offset; with or without offset surface.
• Directions of the resulting 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 ability to adjust or not.

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 work normally even under high shock and vibration loads or at a sufficiently high speed.
• Fairly economical if a large diameter shaft is used.
• Able to use as a split bearing.
• Ability to provide gap adjustment, which canthe axis of the shaft is set with the utmost precision.

Flaws

At the same time, of course, such products have some disadvantages:

• Contrary to how the designation of rolling bearings is indicated, this is not the highest efficiency, since there are quite significant friction losses.
• No chance of proper operation without regular lubrication.
• Uneven wear of the trunnion and the product itself.
• Relatively high cost due to the need for regular use of non-ferrous metals in the production process.
• Huge labor intensity in manufacturing.

Marking

All products that are manufactured in Russia must be marked by manufacturers without fail, and the designation of bearings is established in accordance with GOST. 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 right of the main designation. At the same time, it is worth noting the fact that the additional marking on the left should always be separated from the main one 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.

The left signs, which include the designation of bearings in the drawing, contain the following:

• friction moment;
• product category;
• accuracy class;
• radial clearance group.

The following is indicated on the right:

• constructive changes;
• material used in the manufacturing process of these parts;
• lubricant;
• holiday temperature;
• basic requirements to ensure a certain level of vibration.

Diameters

If we are talking about the designation of diameters, the size of which is not more than 10 mm, then the value of the nominal diameter is considered, and the only exception here are bearings with bores with a diameter in the range of 0.6-2.5 mm, the designation of which is carried out fractional number. In other situations, if the diameter has a fractional value, then in this case the designation will be rounded to the nearest integer, while the number “5” is placed in the second place in the designation of this product.

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

If the diameter of the hole is 22, 28, 32 or 500 mm, then fractional values are indicated. 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 inIn this case, they are designated as quotients rounded to an integer from dividing the present diameter by 5. In this case, the main designation of such products includes the number “9” in the third place.

The inner diameter of bearings with a bore larger than 500 mm has a designation that is exactly the same as the indicated value of the bore diameter calculated in millimeters.

Among other things, the dimension series of the bearing is indicated, which includes a combination of width and diameter series to determine the exact dimensions.