JP2008002532A - Steel equipment bearings - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate the surface modification even in a large bearing and prevent the occurrence of smear while suppressing metal contact even when a rolling element and a lace surface have high surface pressure and cause rolling slide movement in a boundary region between load zone and non-load zone so as to inhibit the formation of oil film. <P>SOLUTION: A corrosion resisting film 2 made of a metal baser than iron such as Al, Zn and Bi is formed by shot peening in at least one of a raceway surface of an inner ring 5, a raceway surface of an outer ring 4 and a rolling surface 3 of a rolling element composing a bearing 1 for steel facilities. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steel equipment bearing, and is particularly suitable for application to a friction reduction processing method by rolling and sliding between a rolling element and a race surface.

In steel rolling mills and the like, large roller bearings for roll necks having a maximum diameter exceeding 300 mm are used, and such seizure shafts (hereinafter also referred to as smears) are caused by metal contact. Sometimes.
FIG. 6 is a diagram illustrating a relationship between a load zone and a non-load zone that cause smear of a bearing for steel facilities.
In FIG. 6, an inner ring raceway surface 55a and an outer ring raceway surface 54a are formed in the roller bearing 51, and a roller 53 is disposed between the inner ring raceway surface 55a and the outer ring raceway surface 54a so as to be able to roll.

  A large radial load is applied to the roller bearing 51 by pressurization, and a load zone 55 where a load is applied to the roller 53 and a non-load zone 56 where no load is applied to the roller 53 and not restricted by the inner and outer rings are generated. In the non-load zone 56, the rollers 53 by the inner and outer rings are not restrained, so that the driving force for rotating the rollers 53 decreases, and the rotation speed of the rollers 53 differs between the load zone 55 and the non-load zone 56. When the roller 53 revolves in such a state, since the rapid rotation of the rotation is performed in the boundary region between the load zone 55 and the non-load zone 56, the roller 53, the outer ring raceway surface 54a, and the inner ring raceway surface 55a (hereinafter referred to as both). It is also called the race surface.) Rolling and sliding contact.

  In order to prevent metal contact due to rolling and sliding contact, an oil film is formed on the race surface using grease, but the roller bearing 51 used for a steel rolling mill or the like is rolled. Water is mixed, which is an unfavorable operating condition for oil film formation. For this reason, the oil film is broken on the rolling surface and the race surface of the roller 53, and smear is generated. As a technique for providing a lubrication function in such an environment where lubricating oil or grease cannot be used, there is a method of modifying the race surface by plating, sputtering or ion plating (Patent Documents 1 and 2).

Further, at least one of the inner ring raceway surface 55a, the outer ring raceway surface 54a, the rolling surface of the roller 53 or the cage guide surface constituting the bearing, a solid lubricant containing at least molybdenum disulfide and tetrafluoroethylene. A method of applying a friction-reducing surface treatment with a binder is also known (Patent Document 3).
JP-A-3-121313 Japanese Patent Laid-Open No. 3-172611 Japanese Patent Laid-Open No. 8-166021

  However, the techniques disclosed in Patent Documents 1 and 2 are intended for environmental considerations such as prevention of dust generation, but the target bearing is relatively small. In addition, it is difficult to apply to a large bearing represented by a roll neck bearing having an inner diameter of 150 mm or more from the viewpoint of surface treatment equipment. Further, the surface modification method of the bearing race surface shown in these Patent Documents 1 and 2 is by plating, sputtering, ion plating or the like, and the process is long and diverse. There was a problem that it would be a factor of cost increase.

Moreover, although the technique disclosed in Patent Document 3 is effective in preventing smear, a technique that can cope with further surface damage as the total rolling tonnage increases is desired.
Therefore, the object of the present invention is that surface modification can be easily applied even to a large bearing, and the rolling element and the race surface have a high surface pressure and a rolling sliding motion in the boundary region between the load zone and the non-load zone, thereby forming an oil film. An object of the present invention is to provide a steel facility bearing capable of preventing smear from occurring while suppressing metal contact even when hindrance is inhibited.

In order to solve the above-described problem, according to the steel equipment bearing according to claim 1, at least one of the steel inner ring raceway surface, the outer ring raceway surface, and the rolling element transfer surface constituting the steel equipment bearing. Further, a metal film that is lower than iron is formed by shot peening.
This makes it possible to form a corrosion-resistant coating on the surface of the bearing steel by a simple method called shot peening, while also allowing the coating to diffuse inside the base material and to adhere the coating firmly to the surface of the bearing steel. Can be made. For this reason, surface modification can be easily applied even to large bearings, and rolling elements and the race surface have high surface pressure and rolling sliding movement in the boundary region between the load zone and non-load zone, and oil film formation is inhibited. However, since it is possible to prevent smear while suppressing metal contact, it is possible to inexpensively mass-produce bearings for steel facilities with good durability even in an environment where water is mixed.

According to the steel equipment bearing according to claim 2, at least one of the steel inner ring raceway surface, the outer ring raceway surface and the rolling element transfer surface constituting the steel equipment bearing is made of a base metal than iron. It is characterized by comprising a film formed by shot peening an alloy with a noble metal or a mixed powder.
This makes it possible to protect the base metal with a metal that is less likely to rust than iron, to prevent the base material from being rusted, and because the base material is damaged and scratched. Even when exposed, the base material can be protected from rust by sacrificial corrosion protection, and the base material can be effectively protected from rust even in an environment exposed to water or water vapor.

  According to the steel equipment bearing according to claim 3, it is formed by shot peening on at least one of the steel inner ring raceway surface, the outer ring raceway surface or the rolling element transfer surface constituting the steel equipment bearing. And a second layer coating made of a metal noble than iron formed by shot peening on the first layer coating. .

This makes it possible to protect the base metal with a metal that is less likely to rust than iron, it is possible to prevent the rust from occurring on the base material, and even when the second layer coating is damaged, It is possible to oxidize the first layer coating preferentially over the base material and prevent the base material from generating rust, and to effectively protect the base material from rust.
In addition, by making the base metal from iron as the first layer and the noble metal from iron as the second layer, the part where the base metal from iron is exposed to the corrosive environment is the second layer coating. In the case where the second layer coating is damaged, it is possible to delay the progress of oxidation of the first layer coating by sacrificial corrosion protection. Disappearance can be delayed, and the durability of the bearing for steel equipment can be improved.

According to the steel equipment bearing according to claim 4, the base metal than the iron includes at least one of Al, Zn, and Bi, and the noble metal than the iron is Ni, Cr, Cu, Ti. And at least one of Sn.
This makes it possible to protect the base metal with a metal that is less likely to rust than iron, to prevent the base material from being rusted, and because the base material is damaged and scratched. Even when exposed, the base material can be protected from rust by sacrificial corrosion protection, and the durability of the bearing for steel facilities can be improved.

Moreover, according to the steel equipment bearing according to claim 5, the thickness of the entire coating is 0.1 or more and 8 μm or less.
Thereby, it is possible to obtain a sufficient and continuous rust prevention effect within a range in which the rust prevention effect is not saturated, and it is possible to improve the durability of the bearing for steel equipment while suppressing an increase in cost.
Moreover, according to the steel equipment bearing according to claim 6, the thickness of the entire coating is 0.5 to 6 μm.
Thereby, it is possible to obtain a sufficient and continuous rust prevention effect while suppressing peeling of the film.
Moreover, according to the bearing for steel facilities of Claim 7, the thickness of the said whole film is 0.5-5 micrometer.
This makes it possible to obtain a sufficient and continuous rust prevention effect, and eliminates the need for post-processing to adjust the gap after the coating process, thereby reducing the cost.

According to the steel equipment bearing according to claim 8, the depth of the dimple of the base material on which the coating film is formed is 0.1 to 5 μm.
Thereby, the adhesiveness of the film formed in the base material can be improved, and the durability of the bearing for steel facilities can be improved.
According to the steel equipment bearing of claim 9, the outermost surface roughness of the coating formed on the base material is 0.01 or more and 0.5 μmR or less.
Thereby, the adhesiveness of the film formed in the base material can be improved, and the durability of the bearing for steel facilities can be improved.

  As described above, according to the present invention, surface modification can be easily applied even to a large bearing, and the rolling element and the race surface have a high surface pressure and rolling slip in the boundary region between the load zone and the non-load zone. Even when oil film formation is inhibited due to movement, it is possible to prevent smear while suppressing metal contact. Can be mass-produced.

Hereinafter, a bearing for steel facilities according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a schematic configuration of a steel equipment bearing according to an embodiment of the present invention.
In FIG. 1, an iron ring bearing 1 is provided with an inner ring 5 and an outer ring 4 facing each other, and a plurality of rolling elements (rollers) 3 are arranged between the inner ring 5 and the outer ring 4 so as to be freely rollable. In addition, a cage 6 that holds the rolling elements 3 is installed. In addition, as a material of the base material of the inner ring | wheel 5, the outer ring | wheel 4, and the rolling element 3, for example, as a material of the base material of the cage | basket 6, a cold rolled steel plate can be used, for example. And by fixing the shaft 7 to the inner ring 5, the shaft 7 can be rotatably held by the steel facility bearing 1.

  Here, the corrosion resistant coating 2 is formed by shot peening on at least one of the raceway surface of the inner ring 5, the raceway surface of the outer ring 4, and the transfer surface of the rolling element 3. The corrosion-resistant film 2 may be a metal film that is baser than iron or an alloy film that contains a metal that is baser than iron and a noble metal. Alternatively, it may be a two-layer structure composed of a first layer coating made of a metal lower than iron and a second layer coating made of a metal noble than iron. In addition, the base metal than iron may include at least one of Al, Zn, and Bi, and the noble metal than iron may include at least one of Ni, Cr, Cu, Ti, and Sn. .

  Thereby, it becomes possible to form the corrosion-resistant coating 2 on the surface of the bearing steel by a simple method called shot peening, and also to diffuse the coating inside the base material, so that the coating is firmly attached to the surface of the bearing steel. Can be attached. For this reason, surface modification can be easily applied even to large bearings, and the rolling element 3 and the race surface have a high surface pressure and rolling sliding motion in the boundary region between the load zone and the non-load zone, and oil film formation is inhibited. Even in this case, since it is possible to prevent smear while suppressing metal contact, it is possible to mass-produce the steel facility bearing 1 having good durability even in an environment where water is mixed.

  Also, by covering the surface of the base material with a metal noble than iron via a base metal than iron, even when the bearing steel is placed in a wet environment, the base material is oxidized before it is oxidized. Oxidizes a base metal than iron to prevent rusting of the base metal, and it can suppress exposure of a base metal than iron to a moist environment with a metal noble than iron. It is also possible to delay the oxidation of base metals.

The film thickness of the corrosion resistant coating 2 is preferably 0.1 or more and 8 μm or less, more preferably 0.5 or more and 6 μm or less, and most preferably 0.5 or more and 5 μm or less. It is good. The roughness of the outermost surface of the corrosion-resistant coating 2 is preferably 0.01 or more and 0.5 μmR or less.
Further, dimples may be formed on the raceway surface of the inner ring 5, the raceway surface of the outer ring 4, and the base material transfer surface of the rolling element 3 as a pretreatment before forming a coating film. Here, the depth of the dimple of the base material is preferably 0.1 or more and 5 μm or less.
In addition, as a method of measuring the thickness of the film, for example, a method of measuring the diameter before and after treatment with a micrometer or a method of measuring a cross section with an electron microscope can be used.

  Moreover, you may make it use the following method as a method of measuring the thickness of a film. First, for the purpose of protecting the coating, a pyrrolidone solution of polyamide-imide, which is a thermosetting resin, is applied to the rolling surface of the rolling element provided with the coating, and cured by heating at 175 ° C. for 2 hours to protect the coating. A film is formed. This rolling element is cut and embedded in an epoxy resin, and the cut surface of the rolling element is mirror-finished by buffing. Furthermore, in order to give unevenness, after corroding with a 3% picral solution for 5 seconds, a nano-order chromium layer is coated on the surface by sputtering to impart electrical conductivity. Then, 30 views of the cut surface are observed at a magnification of 5000 times with an electron microscope (SEM).

  Also, in the observation with an electron microscope, in order to make the film thickness clearly observable with a reflection electron beam image, in each field of view, observation is made so that the coated surface is traversed in the horizontal direction and divided into 6 in the vertical direction. The thickness of the film is measured at five points, the average value of these five points is determined, and this average value is taken as the thickness of the film in the field of view. And the average value of the film thickness of 30 visual fields can be calculated | required.

FIG. 2 is a cross-sectional view showing a schematic configuration of a shot peening processing apparatus according to an embodiment of the present invention.
In FIG. 2, the shot peening processing apparatus 20 is provided with a tank 32 that houses a projection material 35. A pipe 33 for delivering the projection material 35 is connected to the bottom of the tank 32, and a nozzle 33 a for ejecting the projection material 35 is provided at one end of the pipe 33, and compressed air is provided at the other end of the pipe 33. 34 is supplied. As the projection material 35, for example, low melting point metal stainless particles or carbon steel having a hardness of HRC50 or more and a particle size of about 200 μm can be used, and the projection speed can be set to about 100 m / sec. Further, the projection time can be appropriately set while watching the coated film thickness, and is preferably set to 30 to 60 seconds, for example.

  When a zinc coating is formed on the raceway surface 11a of the rolling sliding member 11, the projection material 35 is ejected from the nozzle 33a by feeding the compressed air 34 into the pipe 33, and the projection material 35 is placed on the raceway surface from the zinc powder. 11a. As a result, the zinc powder can be bonded to the surface layer of the base material by the collision energy of the projection material 35, and it becomes possible to form a strong film and easily produce a film with a uniform film thickness in a short time. Even in a large bearing, surface modification can be easily performed while suppressing an increase in cost.

When a coating is formed on the raceway surface of the inner ring 1 or the raceway surface of the outer ring 2 in FIG. 1, the raceway surface of the inner ring 1 or the raceway surface of the outer ring 2 is arranged and supported on the side of the nozzle 33 a, and the rolling element 3. When a coating film is formed on the transfer surface, a plurality of rolling elements 3 are accommodated in a mesh-like container, and the projection material 35 can be projected while rotating the shaft at a rotational speed of 2 to 5 rpm, for example.
And the durability test of the bearing 11 for steel facilities was evaluated by using a 2-cylinder rolling slide tester.

FIG. 3 is a cross-sectional view showing a schematic configuration of a two-cylinder rolling slip tester according to an embodiment of the present invention.
In FIG. 3, in the two-cylinder rolling and sliding test machine 41, the test piece rings 47 and 48 are combined so that the outer diameter surfaces are in contact with each other. The driving force by 46 is transmitted to the test piece ring 48 through the gears 42 and 42.

  In the specimen rings 47 and 48 having a diameter of 78 mm and a width of 18 mm, a zinc coating is formed on the surface of the bearing steel by shot peening (Example 1), and a coating made of zinc and tin is shot on the surface of the bearing steel. Formed by peening (Example 2), solid lubricant containing molybdenum disulfide and ethylene tetrafluoride subjected to friction reduction surface treatment with a binder (Comparative Example 1), bearing steel surface A film on which no film was formed (Comparative Example 2) was prepared.

Then, the test piece ring 47 is driven by the motor 46, and a relative sliding speed of 3.2 m / s is given to the test piece ring 48 via the gears 42, 42, so that the test piece rings 47, 48 are in rolling contact with each other. It comprised so that it might become. Here, 20 cc of gear oil was applied to the outer peripheral surfaces of the test piece rings 47 and 48 in advance with a syringe. Then, the test piece rings 47 and 48 are set to roll so that the surface pressure of the sliding surface is 100 kgf / mm ^2, and the time until the torque of the test piece ring 47 directly connected to the motor 46 exceeds 100 kgf-cm is set. The durability time (minutes) was used. Further, as water mixing conditions, 100 cc of water was sprayed from the side surfaces of the test piece rings 47 and 48 in the shower 44 and mixed into the sliding surfaces of the test piece rings 47 and 48.

FIG. 4 is a view showing a result of a durability test of a steel facility bearing according to an embodiment of the present invention together with a comparative example.
In FIG. 4, the endurance time could be improved by forming a zinc coating or a coating made of zinc and tin on the surface of the bearing steel by shot peening. Further, it has been found that the method of forming a zinc coating or a coating made of zinc and tin on the surface of the bearing steel by shot peening is effective for smear countermeasures.

FIG. 5 is a diagram showing the relationship between the film thickness and the durability according to an embodiment of the present invention.
In FIG. 5, the film thickness of the zinc film or the film made of zinc and tin is preferably 0.1 or more and 8 μm or less, more preferably 0.5 or less, from the viewpoint of assembly dimension tolerance or durability of the bearing. The thickness is preferably 6 μm or less, and most preferably 0.5 or more and 5 μm or less.

It is sectional drawing which shows schematic structure of the steel equipment bearing which concerns on one Embodiment of this invention. It is sectional drawing which shows schematic structure of the shot peening processing apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows schematic structure of the 2-cylinder rolling sliding test machine which concerns on one Embodiment of this invention. It is a figure which shows the durability test result of the bearing for steel facilities which concerns on one Example of this invention with a comparative example. It is a figure which shows the relationship between the film thickness and durability which concern on one Example of this invention. It is a figure which shows the relationship between the load zone and non-load zone of a steel equipment bearing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Iron and steel equipment bearing 2 Corrosion-resistant film 3 Rolling element 4 Outer ring 5 Inner ring 6 Cage 7 Shaft 11 Rolling sliding member 11a Track surface 20 Shot peening processing device 32 Tank 33 Pipe 33a Nozzle 34 Compressed air 35 Projection material 41 2 Cylindrical sliding Test machine 42, 42 Gear 44 Shower 45 Shaft 46 Motor 47, 48 Specimen ring

Claims (9)

  Iron or steel characterized in that a base metal film is formed by shot peening on at least one of steel inner ring raceway surface, outer ring raceway surface or rolling element transfer surface constituting a steel facility bearing. Bearing for equipment.   Formed by shot peening an alloy or mixed powder of a metal less precious than iron and a noble metal on at least one of the steel inner ring raceway surface, outer ring raceway surface or rolling element transfer surface that constitute the steel equipment bearing A steel facility bearing comprising a coated film. A first layer coating made of a base metal than iron formed by shot peening on at least one of steel inner ring raceway surface, outer ring raceway surface or rolling element transfer surface constituting a steel facility bearing;
A steel facility bearing comprising: a second layer coating made of a metal noble than iron formed by shot peening on the first layer coating.   The metal lower than iron includes at least one of Al, Zn, and Bi, and the metal noble than iron includes at least one of Ni, Cr, Cu, Ti, and Sn. The bearing for steel facilities of Claim 2 or 3.   The steel equipment bearing according to any one of claims 1 to 4, wherein the entire coating has a thickness of 0.1 to 8 µm.   The steel equipment bearing according to any one of claims 1 to 4, wherein the entire coating has a thickness of 0.5 to 6 µm.   The steel equipment bearing according to any one of claims 1 to 4, wherein the entire coating has a thickness of 0.5 to 5 µm.   The bearing for steel facilities according to any one of claims 1 to 7, wherein the dimple depth of the base material on which the coating is formed is 0.1 to 5 µm.   The bearing for steel facilities according to any one of claims 1 to 8, wherein the roughness of the outermost surface of the coating formed on the base material is 0.01 to 0.5 µmR.

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