Restoration of bearing seats using metal polymers using the gluing method.
The essence of this method is that the process of restoring the seat is combined with the assembly operation of the bearing assembly. As a result, a fixed connection between the bearing and the shaft (bearing housing) is formed, which is many times superior in its strength characteristics to the interference fits recommended in such cases, which more reliably protects the bearing rings from turning, eliminating wear and providing more reliable operation node. At the same time, gluing, unlike an interference fit, does not lead to stress and deformation of the bearing rings, which also contributes to more comfortable operation.
To disassemble a bearing assembly restored in this way, it is necessary to heat the metal-polymer layer formed at the gluing site to a temperature above 300 0C or burn it out, for example, using a gas torch.
The main stages of the process of restoring seats using gluing.
I.Restoration of seats with minor (up to 0.25 ÷ 0.3 mm in diameter), uniform wear (without preliminary machining surface to be restored).
1. Prepare the surface to be restored in accordance with general recommendations(clean off dirt, oil, etc., roughen with sandpaper, degrease).
2. Wipe and degrease the bearing seating surface.
3. Carry out a check assembly: the bearing should be installed in the seat quite easily, without significant effort.
4. Protect the bearing cage with adhesive tape or electrical tape from possible metal polymer getting into it when gluing.
5. Prepare the required dose of metal polymer.
6. Apply the required layer or layers of metal polymer to the shaft (housing) seat, thoroughly wetting the surface to be restored.
7. To coat, literally wetting, thin layer metal polymer bearing seat.
8. Install the bearing onto the shaft (into the housing), carefully pressing it against the limiting collars, bushings, and retaining rings.
9. Remove the squeezed out excess metal polymer, clean unprotected areas on the shaft (in the housing) with acetone if metal polymer accidentally gets on them, remove the protection from the separator.
10. After polymerization of the metal-polymer, the assembly is ready for further operation.
Note:
At the specified wear values, the centering of the bearing relative to the shaft (housing) during the gluing process is ensured by both metal-polymer filler particles falling into the gap and additional ways, for example: preliminary punching of the restored surface (usually it is enough to punch the surface that is the supporting one when gluing), centering relative to other parts, etc.
2. Restoration of seats with minor (up to 0.1 ÷ 0.15 mm in diameter) wear.
When restoring by gluing the seats of shafts (housings) with a wear amount of less than 0.1 ÷ 0.15 mm in diameter (the size of the gap is commensurate with the size of the filler particles), it is necessary to pre-bore the seat by 0.5 ÷ 1.0 mm, with by cutting “ragged threads” or grooves. To ensure that the bearing is centered during gluing, boring is carried out leaving bands along the edges of the seat and along its length (the total width of the bands should not exceed 50% of the entire gluing surface) - see Figure 1.
font-size:11.0pt;font-family:Arial">Fig. 1. Restoring the seat on the shaft using metal polymers by gluing the bearing:
D nom. – d 1 = 0.1 ÷ 0.15 mm;
D 1 – d 2 = 0.5 ÷ 1.0 mm;
I – places where “ragged threads” or circular grooves are cut.
The remaining stages of recovery are similar to operations in point 1.
3. Restoration of seats with significant (over 0.5 ÷ 1.0 mm in diameter) and uneven wear.
When restoring seats with significant and uneven wear using the gluing method special meaning have issues of centering and ensuring alignment of the bearing and shaft (bearing housing). These problems can be solved in the following ways.
1. On the worn surface along the forming lines, metal spacers of varying thickness are installed (approximately 0.05 ÷ 0.08 mm thinner than the wear in this place) in the form of narrow metal strips that are longer than the wear site. The free ends of these strips are secured with adhesive tape, thread, etc. near the place of gluing (preferably on a section of the shaft with a smaller diameter). A control installation of the bearing is carried out (the bearing should be installed in the seat quite easily, without significant effort). After this, a metal polymer is applied to the place of wear (the places under the gaskets are also coated). The bearing is installed. After polymerization of the metal-polymer, the leading ends of the spacers are cut off.
2. Small diameters are applied to wear areas by welding. point(to avoid overheating of the shaft) sagging in the form of rings. After this, they are machined to the nominal bearing diameter. The bearing is being inspected. After this, gluing is carried out according to the schemes described above.
3. On worn surfaces, a groove is made to install two or more centering rings. Rings (split) are fixed in prepared grooves by welding or gluing using a metal polymer. The installed rings are machined to the nominal bearing diameter. Next, gluing is done according to the schemes described above.
Other methods of centering the bearing can be used in the process of restoring the seat by gluing using metal polymers.
Attention!
When restoring bearing seats by gluing in, before applying the metal polymer, it is necessary to protect the existing oil channels with adhesive tape or tape.
It happens that the bearing in the crankcase has turned, its seating in the engine block or in the crankcase of some unit (gearbox or rear axle) weakens, and it is impossible to operate a car or motorcycle with such a malfunction, since the bearing seat will break even more. Such a malfunction can occur from repeated or incorrect installation of the bearing into the hole (socket) of the crankcase, lack of lubrication (the bearing jams and it turns), or simply from imprecise manufacturing of the bearing hole. And owners of any vehicle, or simply some kind of machine or unit, often encounter such a malfunction. How to easily get rid of such a malfunction at home, without having galvanic equipment, even the simplest (for zinc coating), we will consider in this article.
Of course, you can increase the diameter of the outer race of the bearing if you cover it with chromium or a layer of zinc, and I already wrote about this (you can read it here). But for this you will need to make special plugs (so that the coating layer does not get on the balls, separator and internal surfaces of the clips), and you will have to tinker with chemicals.
In this same article, we will look at another, even simpler way to increase the outer diameter of the holder, which can be done both in your garage and in field conditions any person, even a schoolboy.
First, let's look at the more common ones traditional methods restoration of broken mounting hole in the bearing, maybe some of the newbies don’t know about them and they will be useful to someone. And after that we’ll look into more rare way, which most repairmen are not aware of.
1 - crankcase, 2 - bushing, 3 - outer race of the bearing.
So, if a bearing is mounted in the crankcase of some kind of unit or its cover, and the mounting hole is broken, then the cover is secured through a faceplate in a lathe, and the crankcase in a carding boring machine, and the diameter of the mounting hole is bored by about 3 - 4 mm and after This is done by pressing a repair sleeve into the bored area, in which inner diameter a little more (with allowance for finishing) and after filling, bore the inner diameter of the bushing to match the diameter of the outer race of the bearing (see Figure 1).
This method is quite common, despite the fact that many craftsmen have to look for cardinate boring or lathe and also make a device for accurately securing the part. In addition, this method will not be suitable if the thickness of the metal of the housing wall becomes thin after boring and does not provide sufficient rigidity to the bearing bore. And this stops many people, and you can’t find a competent machine operator everywhere.
Some “masters” try to get by simply by punching the seating surface, but one can hardly hope that such a “repair” will last for a long time, usually a couple of hours. After all, with this method the bearing race will not lie on the entire surface of the mounting hole, but only on tiny areas (pimples) that have a tiny area. Yes, and the sealed areas quickly become crumpled during installation of the bearing (especially in a soft aluminum crankcase), and the bearing race again begins to dangle and rotate.
The most accessible and effective ways repair, this is when the enlarged bearing hole is not touched at all, but only increases the thickness of the bearing race. And there are also several ways here, this is metal spraying with special installations, which are still very little widespread, this is chrome coating of the holder, and zinc coating of the holder, which is more accessible at home, which I already wrote about (link above in the text).
But there is another little-known, but very simple way to increase the size of any round metal part, and in in this case bearing races, which is not difficult to do at home, in the garage and even while traveling (on the side of the road). Moreover, no special qualifications or any secret skill is required, and any driver who is able to open the hood of his car will cope with this simple operation quite easily, especially if an assistant helps.
The principle of metal extension with this in a simple way, based on the operating principle contact welding. And for work we only need a couple of springs, for example from Moskvich or Volga, a couple of pieces of thick wire (cables with an alligator clip are suitable for “lighting up”) and a well-charged battery, or welding transformer(a powerful starting charger may also work).
1 - battery, 2 - springs, 3 - bearing, 4 - table with stands.
And in order to increase the diameter of the outer race of the bearing, this bearing will need to be rolled between two springs, connecting to the springs electricity(see Figure 3). And as I already said, springs from our domestic cars are suitable, but if the bearing is much larger, for example from a truck, then the width of the springs needs to be chosen wider, from the same truck (you can find old springs at scrap metal collection points, or in car dealerships) .
The length of the springs also depends on the diameter of the bearing, but as a rule, the length of one spring is about a meter, and the second can be cut to half a meter (this will make it more convenient to work). We connect each spring with a cable to the pole pieces of the battery or transformer, ensuring good contact.
You can use terminals from the car to tightly connect the cables to the battery, and you can clamp the cables to the springs using bolts and washers, or powerful alligator clips (such as welding ones). Moreover, the polarity when connecting the springs can be any.
a - overlay thickness 0.1 mm, b - overlay thickness 0.25 mm, c - overlay thickness 0.5 mm.
Rolling is performed several times, and at the same time the surface of the outer race is gradually covered with a large number of small welded tubercles from the metal of the springs (see photo on the left). And it is enough to do a few rollings, and the surface of the outer race of the bearing is already increased to such a diameter that the race will no longer dangle in its broken hole.
It is useful to put on the ends of the upper spring latex gloves and wrap them with tape, or just wrap them with electrical tape. This will avoid short circuit springs and damage to the battery if, during rolling, the upper spring touches the lower spring with its end.
This often happens if the diameter of the bearing being restored is small. And if the bearing has a very small diameter, then it is useful when working on the contrary to turn the upper spring with the deflection upward.
When working with a battery, in order not to damage it, it is useful not to protect the rust on the springs at all, since rust has additional resistance that will prevent an excessive increase in current. But if you wish, you can also connect a rheostat, which can be used to accurately select the required current strength.
If a welding transformer is used instead of a battery, then of course it is better to use one with current regulation. Welding current set in the range of 100 - 150 amperes, and the higher the current, the faster the metal will grow, but the larger the deposited particles will be.
Therefore, it is useful to choose a middle ground so that the particles of the deposited metal (inclusions) are not large, and you don’t have to fuss for a long time. You can practice on a bad bearing first. But as a rule, for a normal increase in the diameter of a 110 mm bearing by 0.5 mm, a current of 150 amperes and about five minutes of knurling will be required. And at the same time, the bearing heats up to only 100 degrees, which means the structure of its metal does not change.
After knurling, as can be seen in the photographs, the surface of the holder has a somewhat rough appearance, which is even better, since it will never turn in its hole again (the adhesion of a rough surface is better than a smooth one). But still, if someone wants to restore the surface of the outer race in this way to the factory smooth state, then it is quite possible to make the coating twice as thick (instead of 0.5 mm, make 1 mm). And after that, give the bearing to a turner, who will polish the race until smooth, removing about 0.5 mm from the surface.
Using the method described in this article, the seating of bearings that had turned in their places was restored not only passenger cars both motorcycles, but also trucks, and quite a lot of money was saved, since the crankcase or rear, hub, or engine block no longer needed to be changed, which is what I wish for you; Good luck everyone.
Seats often cannot be repaired, and then the question arises of replacing the part associated with the bearing and which has lost the nominal parameters of the seat. This type of repair is not economically feasible. The solution in this situation is repair using Dimet technology.
Let's look at examples of repairing seats using the cold gas-dynamic spraying method.
Motorcycle hub bearing seat.
The defect of the seat is that the outer ring of the bearing rotates during operation, which puts additional loads on the axis of the inner ring and on the bearing itself.
Image 1. Seat for the outer bearing race on a cross-country motorcycle wheel.
To eliminate this problem, it is necessary to add a layer of metal to the inner diameter of the hub. The hub is made of aluminum alloy. Before applying the composition, we pre-treat the surface with abrasive composition K-00-04-16. The application of an additional layer is carried out in the third mode of the Dimet-405 apparatus. Spraying is carried out with a reserve. The final processing of the coating is carried out at low cutter feed at high speeds.
Image 2. Stages of repair (a - aluminum layer applied with a reserve, b - finishing version of the finished seat)
Crankshaft half ring seat
The seat of the remote semi-ring of the crankshaft of the cast-iron Mercedes-Benz cylinder block was repaired using Dimet technology. The final processing was carried out with a special cutter.
Wheel bearing seat
Repair of the Ford cast iron hub seat was carried out by applying an aluminum layer 0.3 mm in size. These manipulations provided the necessary tension in the connection.
Image 1. Stages of repair (a – initial, b – final)
Electric motor bearing seat
Repair of bearing seats in the electric motor housing was carried out using an aluminum composition device, spraying mode - “3”. The images show the stages of repair.
Owners of patent RU 2296660:
The invention relates to the field of mechanical engineering, namely to methods for restoring seats of rolling bearings. The bearing assembly is dismantled and the surface of the seats deformed when using the bearings is treated with solutions. A molten restoration material, which crystallizes at a temperature of 70°C and melts at a temperature above 340°C, is applied to the deformed surface of the bearing seats treated with solutions. The restoration material has viscous properties and strength-mechanical characteristics corresponding to the material of the bearing seats. Then the bearing is heated in oil to a temperature of 80-90°C. The bearing assembly is assembled by installing the heated bearing on its seats. As a result, costs are reduced and labor intensity is reduced. repair work.
The invention relates to the field of mechanical engineering and other industries where rolling bearings are used under heavy loads, leading to deformation of the rolling bearing seats.
There is a known method for restoring worn crankshafts, in which the journals are mechanically processed with technological penetration into the body of the restored surface over the entire width between the cheeks of the journal with the formation of fillets and subsequent heat treatment of the crankshaft. A metal wear-compensating lining in the form of a split ring or half rings is secured to the treated necks by welding their joints. The weld seam is located in an area limited by 25-50° of rotation of the crankshaft from top dead center, and the second seam, when using half rings, is positioned relative to the first with a rotation of 180°. Cool the weld to a temperature environment, providing a tension of the split ring of 0.1...0.15 mm. When using a split ring, it performs through holes with a diameter of 5-7 mm. The hole in the split ring with the shaft neck, which is located opposite the weld, is welded first, and the remaining holes are welded, symmetrically approaching weld seam, which will increase the fatigue strength of the crankshaft to the level of a new part while simultaneously restoring worn journals to the nominal size.
There is a known method for repairing a bearing assembly, which includes disassembly, troubleshooting parts, assembly in the form of installation on the seating surface of the outer ring of a worn bearing of two locally diametrically opposed plates and assembly. The thickness of the plates is determined by the formula Sc=Sr+Su, where Sc is the total thickness of the plates; Sr - radial clearance in a worn bearing; Su - gap in the connection between the housing bore and the outer ring of the bearing, taking into account wear. The length of each local plate is determined by calculation.
The disadvantages of this method are the high costs and labor intensity of repair work.
There is a known method for restoring worn surfaces of sliding bearing shafts, which consists in heating the hardened zone of the part with a binding material previously applied to it (for example, from a paste made of a deposited material) in a current inductor high frequency before melting of the binding material and surfacing it to the place of wear of the part, compensating for its wear, characterized in that it is carried out by heating the worn surface of the part to a temperature exceeding by 50-100 ° C the temperature of the critical point AC 3, and then cooling the deposited surface of the worn parts at the rate of hardening, and a material with a melting point not exceeding the hardening temperature of the product material is used as a binder.
The disadvantages of this method are the high costs and labor intensity of repair work.
The closest technical solution adopted for the prototype is the method of restoring crankshafts by building up the worn surface of the sliding bearings, which is realized by lining the journals of the main and connecting rod axes of the crankshaft with split bushings made of a material with high abrasion resistance, welded along the line of their cuts in a tight fit to the surface shaft journals, lubricated with special glue or sealants before contacting the split bushings.
The disadvantage of this method is the high costs and labor intensity of the work.
Comparison of the proposed solution with the prototype and similar solutions known from the existing level of technology allows us to establish its compliance with the patentability criteria of “novelty” and “inventive step”.
The technical result of the claimed invention is to reduce the costs and labor intensity of repair work to restore the seats of rolling bearings.
This technical result is achieved by the fact that the method for restoring the seats of rolling bearings includes dismantling the bearing assembly, treating the surface of the seats deformed during the use of bearings with solutions and assembling the bearing assembly, while, according to the invention, a crystallizing substance is applied to the deformed surface of the bearing seats treated with solutions. temperature of 70°C and a molten reducing material melting at a temperature above 340°C with viscous properties and strength-mechanical characteristics corresponding to the material of the bearing seats, then the bearing is heated in oil to a temperature of 80-90°C and the bearing assembly is assembled by installing a heated bearing into its seats.
The essence of the implementation method is as follows.
A melt of restorative metallized material is applied to the deformed surface of the bearing seat treated with special solutions, and then the bearing heated in oil is installed on its seat. The bearing is heated to a temperature of 80-90°C and, thereby, ensures the heating of the restoration material to a temperature of 70°C, at which the latter crystallizes and gains the strength and mechanical characteristics of the seat material.
The proposed method makes it possible to reduce equipment downtime, costs and labor intensity when restoring seats of rolling bearings.
Literature
1. RF Patent No. 94019772. Ponurovsky A.A. Ponurovsky A.A. Method for restoration of crankshafts and their plain bearings. IPC V23R 6/00. Fast. 1994.05.26. Publ. 1996.09.10. Reg. No. 94019772/02.
2. RF patent No. 2235009. Method for repairing a bearing assembly. / Usov V.V. Seregin A.A. Timoshenko A.N. Seregina V.V. IPC V23R 6/00. Fast. 2001.02.21. Publ. 2002.09.20. Reg. No. 2001105022/02.
3. RF Patent No. 2189298. Method for repairing a bearing unit / Usov V.V. Seregin A.A. Timoshenko A.N. Seregina V.V. IPC V23R 6/00. Fast. 2001.02.21. Publ. 2002.09.20. Reg. No. 2001105022/02.
4. RF patent No. 95117550. A method for restoring worn seating surfaces of shafts for plain bearings. / Ulitovsky B.A., Shkrabak B.S., Ulitovsky S.B., Shkrabak R.V., Polishko G.Yu. IPC V23R 6/00. Fast. 1995.10.17. Publ. 1997.10.20. Reg. No. 95117550/02.
5. RF Patent No. 2105650. A method for restoring worn seating surfaces of shafts - plain bearings. / Ulitovsky B.A., Shkrabak B.S., Ulitovsky S.B., Shkrabak R.V., Polishko G.Yu. IPC V23R 6/00. Fast. 1995.10.17. Publ. 1998.02.27. Reg. No. 95117550/02.
A method for restoring seats of rolling bearings, including dismantling the bearing assembly, treating the surface of the seats deformed when using bearings with solutions and assembling the bearing assembly, characterized in that a crystallizing material that crystallizes at a temperature of 70°C and melts at a temperature above is applied to the deformed surface of the bearing seats treated with solutions. 340°C molten reducing material with viscous properties and strength-mechanical characteristics corresponding to the material of the bearing seats, then the bearing is heated in oil to a temperature of 80-90°C and the bearing assembly is assembled by installing the heated bearing on its seats.
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