Landing
The importance of proper landing
If the rolling bearing with the inner ring is planted on the shaft only with the tension, a dangerous ring slip can occur between the inner ring and the shaft. This is a sliding of the inner ring, which is called "slippage", leads to a ring shift of the rings relative to the shaft, if the landing with tension is not tight. When slipping arises, the fitted surfaces become rough, causing wear and significant damage to the shaft. Abnormal heating and vibration can also occur due to abrasive metal particles penetrating inside the bearing.
It is important to prevent slipping, securely consolidating with sufficient tension, then the ring that rotates, or to the shaft, or in the case. Slocking cannot always be eliminated by axial tightening through the outer surface of the bearing ring. However, as a rule, there is no need to ensure the tension of the rings exposed only to static loads. The landing is sometimes done without any tight of both the inner and outer ring to adapt to certain working conditions, or to facilitate the installation and disassembly. In this case, to prevent damage to the premium surfaces due to slipping, lubrication or other applicable methods should be considered.
Terms of load and landing
| Application load | Bearing work | Terms of load | Landing | ||
| Inner ring | Outdoor Ring | Inner ring | Outdoor Ring | ||
| Rotational | Static | Turning load on the inner ring, static load on the outer ring | Landing with tension | Free landing | |
 |
Static | Rotational | |||
 |
Static | Rotational | Turning load on the outer ring, static load on the inner ring | Free landing | Landing with tension |
 |
Rotational | Static | |||
| The direction of load is not determined due to changes in the direction or unbalanced load | Rotational or static | Rotational or static | Landing with tension | Landing with tension | |
Landing between radial bearings and housing holes
| Terms of load | Examples | Hole tolerances | Axial offset of the outer ring | Notes | ||
| Independent corps | Large bearing loads in thin-walled case or heavy drum loads | Hubs car kers (roller bearings), lifting crane, working wheels | P7 | Impossible | - | |
| Hubs of car operating wheels (ball bearings), vibration screens | N7 | |||||
| Light or oscillating loads | Conveyor rollers, cable pulleys, stretch pulleys | M7 | ||||
| Load direction is not defined | Heavy shock loads | Traction electric motors | ||||
| Independent or discerning cases | Normal or large loads | Pumps, crankshafts, indigenous bearings, medium and large motors | K7. | It is usually impossible | If no axial displacement of the outer ring is required | |
| Normal or Load Loads | JS7 (J7) | maybe | An axial offset of the outer ring is necessary | |||
| Loads of all species | General Application Bearings, Railway Axial Tours | H7 | Easy possible | - | ||
| Normal or high loads | Cabinet bearings | H8. | ||||
| Significant lifting temperature of the inner ring in the shaft | Dryers for paper | G7 | ||||
| Independent corps | Preferably accurate functioning at normal or light loads | Rear ball bearings of grinding spindle, high-speed centrifugal compressor swivels | JS6 (J6) | maybe | For large loads, a more dense landing is used than K. When required high accuracyfor landing should be used very strict tolerances | |
| Load direction is not defined | Front ball bearing grinding spindle, fixed bearings (supports) of high-speed centrifugal compressor | K6. | It is usually impossible | |||
| Preferably accurate functioning and high rigidity With oscillating loads | Cylindrical roller bearings for the spindle of the metal cutting machine | M6 or N6. | Impossible | |||
| Minimum noise level required | Appliances | H6. | Easy possible | - | ||
Notes to the table:
- This table is applicable to cast iron and steel housings. For enclosures made of light alloys, landing should be more dense than in this table.
- Not applicable for special landings.
Landing between radial bearings and shafts
| Terms of load | Examples | Shaft diameter, mm | Shaft tolerance | Notes | |||
| Ball bearings | Cylindrical and conical roller bearings | Spherical roller bearings | |||||
| Radial bearings with cylindrical holes | |||||||
| Preferably Light axial offset of the inner ring on the shaft | Wheels on static axes | All diameters of shafts | g6. | Using G5 and H5 where accuracy is required. In the case of large bearings, you can use F6 for light axial movement | |||
| Light axial displacement of the inner ring on the shaft is not required | Stretch pulleys, cable pulleys | h6. | |||||
| Turning load on the inner ring or uncertain load direction | Electric appliances, Pumps, Fans, Transpotional Tools, Precision Machines, Metal Consumer Machines | <18 | - | - | jS5 | - | |
| 18-100 | <40 | - | jS6 (J6) | ||||
| 100-200 | 40-140 | - | k6. | ||||
| - | 140-200 | - | m6. | ||||
| Normal loads | General use of bearings, medium and large motors, turbines, pumps, indigenous engine bearings, gearboxes, woodworking machines | <18 | - | - | jS5 (J5-6) | k5 and M6 can be used for single-row conical roller bearings and single-row radially resistant bearings instead of K5 and M5 | |
| 18-100 | <40 | <40 | k5-6 | ||||
| 100-140 | 40-100 | 40-65 | m5-6 | ||||
| 140-200 | 100-140 | 65-100 | m6. | ||||
| 200-280 | 140-200 | 100-140 | n6. | ||||
| - | 200-400 | 140-280 | p6 | ||||
| - | - | 280-500 | r6 | ||||
| - | - | over 500. | r7 | ||||
| High Loads or Impact Loads | Railway axial sleeves, vehicles, traction electric motors, structures, equipment, crushing installations | - | 50-140 | 50-100 | n6. | The inner bearing clearance should be greater than CN | |
| - | 140-200 | 100-140 | p6 | ||||
| - | over 200 | 140-200 | r6 | ||||
| - | - | 200-500 | r7 | ||||
| Only axial loads | All diameters of Vala | jS6 (J6) | - | ||||
| Radial bearings with conical holes and sleeves | |||||||
| All types of loads | General use of bearings, railway toupels | All diameters of shafts | H9 / IT5 | IT5 and IT7 mean that the deviation of the shaft from its true geometric shape, for example, round or cylindrical, must be within the IT5 and IT7 tolerances, respectively | |||
| Transmission shafts, woodworking equipment spindles | H10 / IT7 | ||||||
Note: This table is applicable only to solid steel shafts.
The choice of proper landing, ensuring the required purity and value of the tolerances of the sizes of the bearing surfaces is a key factor in ensuring durability, reliability of mechanisms.
Proper landing is the most important condition for the performance of bearings.
Based on the features of the bearing, the ring, which rotates should be fixed on the supporting surface is motionless, with tension, and a fixed ring to get into the hole with a minimum gap, relatively free.
Installation with tension of the rotating ring does not allow it to be shuting, which could lead to wear of the supporting surface, contact corrosion, the unbalance of bearings, the collapse of the support, excessive heating. So, mostly, the bearing landing is performed on the shaft, which works under load.
For a fixed ring, a small clearance is even useful, and the possibility of the flavor is not more often over a day makes wear of the reference surface more uniform, minimizes it.
Major terms
Consider in more detail the main terms and concepts that determine the bearing fit. Modern engineering is based on the principle of interchangeability. Any detail made by one drawing should be installed in the mechanism, perform its functions, be interchangeable.
For this, the drawing determines not only the dimensions, but also the maximum, minimal deviations from them, that is, tolerances. The tolerance values \u200b\u200bare standardized by a unified system for tolerances, landing ESDP, divided into accuracy degrees (qualificates) are given in tables.
They can also be found in the first volume of the AURUEVA design designer's reference book, and GOST 25346-89, as well as 25347-82 or 25348-82.
According to GOST 25346-89, 20 accuracy qualifications are defined, but in mechanical engineering are usually used from 6 PO16. Moreover, the lower the qualitate number, the higher the accuracy. For landing ball and roller bearings are relevant 6.7, less than 8 qualitets.
Within one qualitate, the size of the tolerance is the same. But the upper and lower deviation of the size from the nominal is located differently and their combinations on the shafts and holes form different landings.
There are landings that ensure the guarantee of the gap, the tension and transition, implementing both the minimum clearance and the minimum tension. Planting is denoted by Latin lower case letters for shafts, large for holes and a digit pointing to the qualificate, that is, the degree of accuracy. Landing Designations:
- with a gap a, b, c, d, e, f, g, h;
- transition JS, K, M, N;
- with tension P, R, S, T, U, X, Z.
On the hole system for all qualifications, it has the admission H, and the nature of the landing is determined by the shaft tolerance. Such a solution reduces the number of required control calibers, the cutting tool and is a priority. But in some cases a shaft system is used in which the shafts have H tolerance, and the landing is achieved by treating the hole. And this case is the rotation of the outer ring of the ball bearing. An example of such a design can serve as rollers or drums tension conveyors.
Selection of rolling bearings
Among the main parameters of the determining landing of bearings:
- character, direction, load size acting on the bearing;
- bearing accuracy;
- rotational speed;
- rotation or immobility of the corresponding ring.
The key condition that determines the landing is immobility or rotation of the ring. For a fixed ring, a landing with a small gap and gradual slow turning is considered a positive factor that reduces the common wear that prevents local wear. The rotating ring is definitely plant with reliable tension that excludes turns relative to the planting surface.
The next important factor to which the bearing landing should be counted on the shaft or in the hole is the type of loading. There are three key types of loading:
- circulating when rotating the ring relatively permanent in one direction of the radial load;
- local for a fixed ring relative to radial loading;
- oscillatory with radial load fluctuating relative to the ring position.
According to the degree of accuracy of bearings, in order of their increase, correspond to five classes of 0.6,5,4,2. For mechanical engineering under loads of low and medium size, for example, for gearboxes, it is common to class 0, which is not specified in the designation of bearings. With higher accuracy requirements, the sixth grade is used. At elevated speeds 5.4 and only in exceptional cases, the second. An example of sixth grade 6-205.
In the process of real designing machines, the bearing landing on the shaft and the body is selected in accordance with the working conditions on special tables. They are given in Tom of the second reference book of the engineering builder Vasily Ivanovich Anurieva.
For a local type of load, the table offers the following landings.
Under the conditions of circulation loading, when the radial force affects the entire rolling path, take into account the loading intensity:
PR \u003d (k1xk2xk3xfr) / bWhere:
k1 - the overload coefficient of dynamic;
k2 is the attenuation coefficient for the hollow shaft or the case of thin-walled;
k3 - coefficient determined by the exposure of axial efforts;
FR - Radial effort.
The value of the K1 coefficient during overloads is less than one and a half times, a small vibration and jolts are taken equal to 1, and with possible overload from one and a half to three times, strong vibrations, blows k1 \u003d 1.8.
The values \u200b\u200bof the K2 and K3 are selected on the table. Moreover, for K3, the ratio of the axial load to the radial, expressed parameter Fc / FR x Ctgβ, is taken into account.
Relevant coefficients and parameter of the loading intensity of the bearing planting are shown in the table.
Treatment of seats and designation of landings for bearings in the drawings.
The landing space for the bearing on the shaft and in the case must have nasal chamfer. Roughness of the landing room is:
- for the neck of the shaft with a diameter of up to 80 mm under the bearing of class 0 Ra \u003d 1.25, and with a diameter of 80 ... 500 mm Ra \u003d 2.5;
- for the neck of the shaft with a diameter of up to 80 mm under the bearing of class 6.5 Ra \u003d 0.63 A with a diameter of 80 ... 500 mm Ra \u003d 1.25;
- for the hole in the case with a diameter of up to 80 mm under the class bearing 0 Ra \u003d 1.25, and with a diameter of 80 ... 500 mm Ra \u003d 2.5;
- for the hole in the case with a diameter of up to 80 mm under the bearing of class 6,5.4 Ra \u003d 0.63, and with a diameter of 80 ... 500 mm Ra \u003d 1.25.
The drawing also indicates the deviation of the shape of the landing site of bearings, the skipping of the blowers for their emphasis.
An example of the drawing, which indicates the bearing landing on the shaft F 50 K6 and the deviation of the form.
The values \u200b\u200bof the form deviations are accepted along the table, depending on the diameter, which has a bearing planting on the shaft or in the housing, the accuracy of the bearing.
In the drawings indicate the diameter of the shaft and the housing under the landing, for example, F20K6, F52N7. On assembly drawings, you can simply specify the size with the admission in the letter notation, but in the drawings of the parts, it is desirable in addition to the alphabetic notation of the admission to bring its numerical expression for the convenience of workers. Dimensions in drawings are indicated in millimeters, and the value of admission in micrometers.
It happens that the bearing in the crankcase has been checked, its landing in the engine block or in a crankcase of some unit (gearbox or rear axle) weakens, and it is impossible to operate a car or a motorcycle with such a malfunction, since the bearing seat is even more separated. Such a malfunction can occur from repeated or improper mounting of the bearing into the hole (socket) of the crankcase, lack of lubricant (the bearing clinite and it turns), or simply from the inaccurate manufacturer of the bearing opening. And with such a malfunction, the owners of any vehicle are often faced, or just some kind of machine or aggregate. How to get rid of such a malfunction at home, without having electroplating equipment, even the simplest (for coating zinc), we will consider in this article.
Of course, you can increase the diameter of the outer bearing, if you cover it with chromium, or a layer of zinc, and I already wrote about it (you can read here in). But for this it will be necessary to make special plugs (so that the coating layer does not hit the balls, the separator and the inner surfaces by the row), and it will have to be tinted with chimreactles.
In the same article, we will consider another, an even simpler way to build out the outer diameter of the climate, which can be carried out both in its garage and in the field, any person, even a schoolboy.
To begin with, we consider more common traditional methods of restoring the broken flooring in the bearing, someone from the beginners do not know about them and they will use someone. And after that, there will be a more rare way, about which most repairmen do not know.
1 - Carter, 2 - sleeve, 3 - outdoor bearing clip.
So, if the bearing is mounted in a crankcase of some unit or its lid, and the seating hole is broken, the cover is fixed through the tablet in the lathe, and the crankcase in the cardinal-boring machine, and the diameter of the planting hole is robbed by about 3-4 mm and after This is pressed into a crocheted place the repair sleeve, in which the inner diameter is slightly larger (with the allowance for the finishing processing) and after the completion, the inner diameter of the sleeve under the diameter of the outer bearing cage is mounted (see Figure 1).
This method is quite common, despite the fact that many masters have to look for a cardinal-boring or lathe and make a fixture for accurate fixing the part. In addition, this method does not suit if the thickness of the metal wall of the case, after the boring it becomes fine and will not provide sufficient hardness of the bearing hole. And it stops many, and the competent stallow is not everywhere you will find.
Some "Masters" are trying to do it at all just with a landing surface, but it is hardly worth hoping that such a "repair" is enough for a long time, as a rule for a couple of hours. After all, the bearing rope with this method will not lie on the entire surface of the planting opening, but only on the meager sites (sinks), which have a meager area. Yes, and the accuracy places are quickly frozen when mounting the bearing (especially in a soft aluminum crankcase), and the bearing clip starts hanging out and turning.
The most affordable and effective methods of repair, this is when the increased bearing hole does not touch at all, but only engage in the bearing wall thickness. And there are several ways here are also a few, this is a metal spraying with special installations that are still very common, it is the coating of the cloth chrome, well, and more affordable at home coverage of the cincation zinc, which I have already written.
But there is another little-known, but a very simple way to build up the size of any round metal part, and in this case the bearing role, which is not difficult to accomplish at home, in the garage and even on the trip (on the side of the road). Moreover, special qualifications or some secret craftsmanship will not need, and any driver who can open the hood on its car will cope with this simple operation fairly easily, especially if assistant will help.
The principle of metal extensions in this simple way is based on the principle of operation of contact welding. And for work, we will need only a pair of sprief, for example, from a Muscovite or Volga, a couple of pieces of thick wire (cables are suitable with a crocodile clamp, and a well-charged battery, or a welding transformer (can come up with a powerful Charger).
1 - Battery, 2 - Springs, 3 - Bearing, 4 - table with stands.
And in order to increase the diameter of the outer bearing, this bearing will need to roll between the two springs, connecting the electric current to the springs (see Figure 3). And as I said, the springs are suitable from our domestic machines, but if the bearing is much larger, for example, from a truck, then the width of the spring must be chosen, from the same truck (you can find old springs at scrap metal, or in autoship items) .
The length of the spring also depends on the diameter of the bearing, but it usually grabs the length of one springs near the meter, and the second can be cut off to half a meter (it will be more convenient to work). We connect each ref of the cable with the pole tips of the battery or transformer, ensuring good contact.
You can use the terminals from the car to connect the cables to the battery tightly, well, and to springs, you can climb cables with bolts with washers, or powerful crocodile clamps (welding type). And the polarity when connecting the springs can be any.
a - the thickness of the surfacing 0.1 mm, b - the thickness of the surfacing of 0.25 mm, B is the thickness of the surfacing of 0.5 mm.
The rolling is performed several times, and at the same time the surface of the outer clip is gradually covered with a large number of smallest welded tubercles from the spring (see photo on the left). And it is enough to make several rolling, and the surface of the outer bearing is already increasing to such a diameter that the clip will no longer hang out in its broken hole.
At the ends of the upper springs it is useful to wear rubber gloves and climb them with a tape, or simply wind the isolent. This will avoid short-circuit springs and damage the battery, if when rolling the upper spring is torn to the bottom of the lower springs.
This often happens if the diameter of the restored bearing is small. And if the bearing is of a very small diameter, then it is useful when working on the contrary, turn the top refrigerant to the upper refrigera.
When working with the battery, in order not to spoil it, it is useful not to protect rust at all at all, as the rust has an additional resistance that will impede the excessive current growth. But if you wish, you can also connect a retail that can accurately select the desired current strength.
If, instead of the battery, a welding transformer will be used, then of course it is better to use the one on which there is a current adjustment. The welding current is exhibited within 100 - 150 amps, and the current more, the faster the metal extension will occur, but the particles will be larger.
Therefore, it is useful to choose the golden middle, so that the particles of the metal (inclusions) are not large, and it has not had to mess around for a long time. It is possible to stretch first on the unsuitable bearing. But as a rule, for a normal increase in the diameter of the 110-millimeter bearing by 0.5 mm, a current of 150 amps will be required and approximately five minutes of rolling. And at the same time the bearing is heated only to 100 degrees, which means the structure of its metal does not change.
After the knob, as can be seen in the photos, the clumum surface has a few rough look, even better, as it will never be checked in his hole (the clutch of the rough surface is better than smooth). But still, if someone wants to restore in this way the surface of the outer clip to the factory smooth state, then it is quite possible to make a coating twice as thicker (instead of 0.5 mm make 1 mm). And after that, give the bearing to the turner, which polishes the clip to the smooth state, removing from the surface about 0.5 mm.
The method described in this article was restored to landing not only cars and motorcycles, but also trucks, and were saved not small money, since the crankcase or rear, hub, or the engine block no longer needed to change, what and you wish you; Good luck everyone.
Recovery using metal-plates under the bearings by plying.
The essence of this method is that the process of restoring the landing place is combined with the assembly operation of the bearing assembly. As a result, a fixed bearing and shaft compound (bearing housing) is formed, which is many times superior in its strength characteristics recommended in such cases of landing with a tension that more reliably protects the bearing rings from the gross, eliminating the appearance of wear and providing more reliable operation of the node. At the same time, plying, unlike landing with tension, does not lead to the appearance of stresses and deformations of the bearing rings, which also contributes to more comfortable work.
To disassemble the bearing assembly restored in this way, it is necessary to heat the metal flux in the place of the layer of the metal flux to the temperature above 300 0s or burn it, for example, using a gas burner.
The main stages of the process of restoring seats using inserts.
I.Restoration of seats with minor (up to 0.25 ÷ 0.3 mm in diameter), uniform wear (without preliminary mechanical processing of the surface restored).
1. Prepare a restored surface in accordance with the general recommendations (clean from dirt, oil, etc., give roughness elaborate paper, degrease).
2. Wipe and degrease the planting surface of the bearing.
3. Conduct the control assembly: the bearing should be installed on the landing place quite easily, without significant effort.
4. Protect the bearing separator by sticking with a sticky ribbon or a tape from possible to enter it with a metal flux in plying.
5. Prepare the necessary dose of metal flock.
6. Apply a shaft (housing) seat or metal flue layers, carefully wetting the surface to be restored.
7. Loss, literally wetting, thin layer of metal bottle of bearing seat.
8. Install the bearing on the shaft (in the housing), thoroughly pressing it to restrictive browns, bushings, locking rings.
9. Remove the extinct excess metal flux, clean the unprotected places on the shaft (in the housing) with a random item on them, remove the protection from the separator.
10. After the polymerization of the metal, the node is ready for further operation.
Note:
With the specified wear values, the bearing centering relative to the shaft (housing) in the stuffing process is provided by both metal filler particles entering the gap and in addition methods, for example: the preliminary core of the surface being restored (it is usually sufficient to raise the surface being supported when inserted), with centers relative to other parts etc.
2. Restoration of seats with minor (up to 0.1 ÷ 0.15 mm in diameter) wear.
When the shafts (enclosures) with a value of wear are less than 0.1 ÷ 0.15 mm in the diameter (the size of the gap is comparable with the size of the filler particles), it is necessary to produce a preliminary boring of the seating area by 0.5 ÷ 1.0 mm, with cutting "ribbon thread" or grooves. To ensure, when plying the centering of the bearing, the boring is carried out with leaving the belt at the edges of the landing place and at its length (the overall width of the belt should not exceed 50% of the entire gluing surface) - see Figure 1.
font-Size: 11.0PT; font-face: arial "\u003e Fig. 1. Recovery by means of water plates on the shaft by the method of plying bearing:
D Mr. - D 1 \u003d 0.1 ÷ 0.15 mm;
D 1 - d 2 \u003d 0.5 ÷ 1.0 mm;
I. - Slices of "torn thread" or ring grooves.
The remaining restoration steps are similar to operations under paragraph 1.
3. Restoration of seats with significant (over 0.5 ÷ 1.0 mm in diameter) and uneven wear.
When restoring the method of stuffing places with significant and uneven wear, the issues of centering and ensuring the coaxialness of the bearing and shaft (bearing housing) are of particular importance. These problems can be solved in the following ways.
1. On the worn surface along the forming lines, metal gaskets of various thicknesses are installed (approximately 0.05 ÷ 0.08 mm thinner wear in this place) in the form of narrow metal strips, superior to the length of wear. The free ends of these bands are fixed with sticky ribbon, thread, etc. next to the place of insertion (preferably on the tree plot with a smaller diameter). The bearing control unit is performed (the bearing must be installed on the landing space fairly easy, without significant effort). After that, a metal-polymer is applied to the place of wear (places under the gaskets are also missing). Installed bearing. After the polymerization of the metal - the jamming ends of the gaskets are cut.
2. Small wear in diameter with welding are applied point (To avoid overheating of the shaft) in the form of rings. After that, their groove is produced to the rated planting diameter of the bearing. The bearing control installation is performed. After that, the patches are made according to the schemes described above.
3. On the worn surfaces, a duty is performed for installing two or more centering rings. Rings (cut) are fixed in the prepared grooves with welding or plying with a metal flux. The installed rings are pulled to the landing nominal bearing diameter. Next, plying is made according to the schemes described above.
Other methods for centering the bearing can also be used in the process of restoring the seating by the method of inserts using metal-polymer.
Attention!
When restoring the stuffing places under the bearings before applying the metal, it is necessary to protect the available oil channels with a sticky ribbon, tape.
Plants often cannot be repaired and then the question of replacing the part conjugate with the bearing and lost the nominal seating parameters. Such a repair option is rather economically inexpedient. The output in this situation is repairs using dieth technology.
Consider examples of the repair of seats by the method of cold gas-dynamic spraying.
Motorcycle hub bearing seat.
The landing site defect is that the external ring of the bearing is rotated when working, which gives additional loads on the axis of the inner ring and the bearing itself.
Image 1. Location for an external bearing ring on a cross motorcycle wheel.
To eliminate this problem, add a metal layer to the inner diameter of the hub. The hub is made of aluminum alloy. Before applying the composition, pre-process the surface with abrasive composition K-00-04-16. Application of an additional layer is performed in the third mode of the DIMET-405 apparatus. Spraying is made with a margin. The completion of the coating processing is carried out with a small supply of the cutter at elevated circulation.
Image 2. Stages of repair (A - applied with a margin aluminum layer, b - finishing option of a finished seat)
Single Crankshaft Planning
Repair of the landing place of the remote semiring of the crankshaft of the cast-iron cylinder cylinder "Mercedes-Benz" with the help of dieth technology is performed. The final processing was produced by a special cutter.
Hub Bearing Plant
Repair of the landing place of the cast iron hub "Ford" is made by applying an aluminum layer, the size of 0.3 mm. The manipulation data provided the necessary tension in the connection.
Image 1. Repair stages (A - initial, b - final)
Electric Motor Bearing Plant
Repair of the landing places of bearings in the electric motor body is made by the device, aluminum composition, spraying mode - "3". Images are represented by the repair stages.