JP2009007602A - Rust prevention treatment method and rolling device - Google Patents

Abstract

An object of the present invention is to provide a rust prevention treatment method in which corrosion of a base material and reduction in mechanical strength hardly occur. Further, the present invention provides a rolling device that is resistant to rusting and has a long life.
A self-aligning roller bearing includes an inner ring, an outer ring, a plurality of rolling elements disposed between a raceway surface of an inner ring and a raceway surface of an outer ring so as to be freely rotatable. It has. At least one of the inner ring 1, the outer ring 2 and the rolling element 3 has a first metal having an oxidation-reduction potential of less than −0.44 V and an oxidation-reduction potential of −0. A rust preventive coating containing a second metal of 43 V or higher and at least one of the oxide of the first metal and the oxide of the second metal is provided.
[Selection] Figure 1

Description

  The present invention relates to a method for preventing rust of a steel material. The present invention also relates to a rolling device such as a rolling bearing, a linear guide device, a ball screw, a linear motion bearing, and the like, and more particularly, to a rolling device that hardly causes rusting.

  Conventionally, there have been electroplating and chemical plating as techniques for imparting rust prevention to the surface of a metal material. For example, alloy electroplating has been widely used as industrial plating for automobile parts, electronic parts, and the like because of its excellent corrosion resistance, workability, and solderability. Moreover, as a lead-free low melting point tin alloy plating that replaces the tin-lead alloy plating, an inexpensive tin-copper alloy plating is used as a bonding material having corrosion resistance for connector parts and the like.

On the other hand, in mechanical parts such as gears and bearings, unlike in the case of the electronic parts described above, the stress is concentrated on the surface of the metal material, so the mechanical strength decreases due to fatigue. When the surface is coated with an alloy film, there is a problem that the mechanical strength is further lowered due to the penetration of hydrogen. Therefore, steel coating bearings and vehicle bearings that require rust prevention cannot be coated with an alloy coating by electroplating. Rust has gone.
JP 2000-282255 A JP-A-6-228786 JP 2005-307227 A

However, a chemical conversion coating such as a manganese phosphate coating is a corrosion coating applied after the base material is slightly corroded or corroded. Therefore, when chemical conversion treatment is applied to the bearing raceway surface, depending on the degree of corrosion, peeling may occur from that part, and the life may be reached in a shorter time than the rusting life without chemical conversion treatment. was there.
Accordingly, an object of the present invention is to solve the above-described problems of the prior art and to provide a rust preventive treatment method in which corrosion of the base material and mechanical strength are unlikely to occur. Another object of the present invention is to provide a rolling device that does not easily rust and has a long life.

In order to solve the above problems, the present invention has the following configuration. That is, the rust preventive treatment method of claim 1 according to the present invention includes a first metal having a redox potential of less than −0.44 V, a second metal having a redox potential of −0.43 V or more, A surface of the steel material is coated with a rust-proof coating containing at least one of the first metal oxide and the second metal oxide.
The rust preventive treatment method according to claim 2 of the present invention is the rust preventive treatment method according to claim 1, wherein the first metal powder and the second metal powder are applied to the surface of the steel material. The anticorrosive film is coated by shot peening that is sprayed.

Furthermore, the rust preventive treatment method according to claim 3 of the present invention is the rust preventive treatment method according to claim 1 or 2, wherein the amount of oxygen in the rust preventive coating is 5% by mass or more. And
Furthermore, the rust preventive treatment method according to claim 4 of the present invention is the rust preventive treatment method according to claim 3, wherein the oxygen amount is a value obtained by correcting a measured value obtained by fluorescent X-ray spectroscopy by the ZAF method. It is characterized by being.

Furthermore, the rolling device according to claim 5 of the present invention has an inner member having a raceway surface on the outer surface, and a raceway surface facing the raceway surface of the inner member, and is disposed on the outer side of the inner member. In the rolling device comprising: an outer member that is formed, and a plurality of rolling elements that are arranged to freely roll between the raceway surfaces, at least of the inner member, the outer member, and the rolling element One is a first metal having an oxidation-reduction potential of less than −0.44 V, a second metal having an oxidation-reduction potential of −0.43 V or more, and at least a part of the surface, A rust preventive coating containing at least one of a metal oxide and a second metal oxide is provided.
Furthermore, the rolling device according to a sixth aspect of the present invention is the rolling device according to the fifth aspect, wherein the rust preventive coating comprises the powder of the first metal and the powder of the second metal. It is formed by shot peening sprayed on the surface.

Furthermore, the rolling device according to claim 7 of the present invention is the rolling device according to claim 5 or 6, wherein the amount of oxygen in the anticorrosive coating is 5% by mass or more. .
Furthermore, in the rolling device according to claim 8 according to the present invention, in the rolling device according to claim 7, the oxygen amount is a value obtained by correcting a measured value by a fluorescent X-ray spectroscopic analysis method by a ZAF method. It is characterized by.

  The present invention can be applied to various rolling devices. For example, a rolling bearing, a ball screw, a linear guide device, a linear motion bearing, and the like. Further, the inner member in the present invention means an inner ring when the rolling device is a rolling bearing, a screw shaft when the ball screw is also used, a guide rail when the linear guide device is used, and a linear motion bearing. Means each axis. The outer member is the outer ring when the rolling device is a rolling bearing, the nut when it is a ball screw, the slider when it is a linear guide device, and the outer cylinder when it is also a linear bearing. Each means.

  According to the rust preventive treatment method of the present invention, the steel material can be subjected to the rust preventive treatment without causing the corrosion of the base material and the mechanical strength. In addition, the rolling device of the present invention has a long life with little rusting.

An embodiment of a rolling device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial longitudinal sectional view showing a structure of a self-aligning roller bearing which is an embodiment of a rolling device according to the present invention.
This self-aligning roller bearing includes an inner ring 1 (inner member), an outer ring 2 (outer member), two rows of spherical rollers 3 disposed between the inner ring 1 and the outer ring 2 so as to be freely rollable, A cage 4 for holding the spherical roller 3 is provided between the inner ring 1 and the outer ring 2, and a lubricant (not shown) is disposed in a space formed between the inner ring 1 and the outer ring 2. And the raceway surfaces 1a and 1a of the two rows of spherical rollers 3 are formed on the outer circumferential surface of the inner ring 1, and the outer diameter of the portion of the outer circumferential surface of the inner ring 1 where the raceway surfaces 1a and 1a are formed is the width. The center part is formed larger than both ends in the direction. Further, the inner peripheral surface of the outer ring 2 is a two-row integral spherical raceway surface 2a. In addition, the inner ring | wheel 1, the outer ring | wheel 2, and the spherical roller 3 are comprised with the same kind or different kind of steel.

At least one of the inner ring 1, the outer ring 2, and the rolling element 3 is provided with a rust-preventing coating (not shown) on at least a part of its surface. The rust preventive coating includes a first metal having a redox potential of less than −0.44 V, a second metal having a redox potential of −0.43 V or more, an oxide of the first metal, and the And at least one of oxides of the second metal.
The redox potential of steel is -0.44V, but the first metal (that is, a base metal than steel) whose redox potential is less than -0.44V, and the redox potential is -0.43V or more. When the second metal (ie, noble metal than steel) is coated on the surface of the steel material, the first metal having a low redox potential is selected by the local cell action between different metals. Will be oxidized. That is, the corrosion of the inner ring 1, the outer ring 2, and the rolling element 3 made of steel is suppressed by the self-sacrificial anticorrosive action.

Furthermore, since at least one of the oxide of the first metal and the oxide of the second metal is contained in the antirust coating (that is, a part of the metal constituting the antirust coating is passivated). The local battery action is slow. As a result, the anticorrosive action is sustained over a long period.
Although the rust prevention property varies depending on the amount of the metal oxide contained in the rust prevention coating, the oxygen content in the rust prevention coating is preferably 5% by mass or more in order to obtain sufficient rust prevention properties. More preferably, it is 6% by mass or more. This amount of oxygen is a value obtained by correcting the measured value by the fluorescent X-ray spectroscopic analysis method by the ZAF method. The ZAF method is a method for obtaining a true value by applying atomic number effect correction (Z), absorption correction (A), and fluorescence excitation correction (F) to a measured value of fluorescent X-rays of a sample.

  Examples of the first metal include magnesium, aluminum, and manganese. Examples of the second metal include nickel, cobalt, titanium, copper, and silver. The first metal in the present invention is not limited to one made of a kind of metal, and may be a mixture or alloy made of a plurality of metals as long as the oxidation-reduction potential is less than −0.44V. . The same applies to the second metal.

  The location where the anticorrosive film is formed is not particularly limited as long as it is the surface of the inner ring 1, the outer ring 2, and the rolling element 3, and rusting at the location where the anticorrosive film is formed can be suppressed. If a rust preventive film is formed on at least one of the raceway surface 1a of the inner ring 1, the raceway surface 2a of the outer ring 2, and the rolling surface 3a of the rolling element 3, rusting of these surfaces can be suppressed. The self-aligning roller bearing can have a long life. Moreover, since the rust preventive film has lubricity, the lubricity of the self-aligning roller bearing can be improved and the life can be extended.

  The method for forming the anticorrosive film is not particularly limited, but shot peening is preferable. That is, the first metal powder and the second metal powder may be sprayed onto the surfaces of the inner ring 1, the outer ring 2, and the rolling element 3 to form a rust preventive film. If an anticorrosive film is formed by shot peening, an electrochemical method is not used, so that the mechanical strength is not reduced due to the penetration of hydrogen.

  When performing shot peening, the first metal powder and the second metal powder may be sprayed separately or simultaneously. However, after the first metal powder is sprayed to form the first metal film, the second metal powder is sprayed on the film to form the second metal film, If a two-layered antirust coating is formed, the oxidation reaction rate of the first metal can be slowed. Moreover, if the powder of the first metal and the powder of the second metal are mixed and sprayed, a rust preventive film made of an alloy of the first metal and the second metal can be formed. it can. In order to form a more uniform alloy film, it is preferable to spray an alloy powder of the first metal and the second metal.

  In the present embodiment, a self-aligning roller bearing has been described as an example of a rolling device. However, the type of the rolling bearing is not limited to the self-aligning roller bearing, and the present invention includes various types. It can be applied to rolling bearings. For example, radial type rolling bearings such as deep groove ball bearings, angular contact ball bearings, self-aligning ball bearings, needle roller bearings, cylindrical roller bearings, tapered roller bearings, and thrust type rolling bearings such as thrust ball bearings and thrust roller bearings It is a bearing. Furthermore, the present invention can be applied not only to rolling bearings but also to various types of various rolling devices. For example, a ball screw, a linear guide device, a linear motion bearing, or the like.

〔Example〕
The present invention will be described more specifically with reference to the following examples. 1 is substantially the same configuration as the self-aligning roller bearing of FIG. 1, and zinc (redox potential is −0.7268V), tin (redox potential is 0.15V), A bearing (nominal number 24036, inner diameter 100 mm, outer diameter 280 mm, width 100 mm) coated with a rust-proof coating composed of zinc oxide and tin oxide by shot peening was prepared, and its rust-proof property was evaluated.
The inner ring, outer ring, and rollers are made of SCM420 and subjected to carbonitriding. However, SCr420 may be used instead of SCM420, and carburizing treatment may be performed instead of carbonitriding treatment. Further, it may be made of SUJ2 and subjected to sub-quenching or induction quenching.

  In shot peening, a mixed powder of zinc powder and tin powder having an average particle size of 30 μm (as defined in JIS R6001) is applied at a jetting pressure of 0.5 MPa using a shot peening apparatus 20 as shown in FIG. This was done by spraying for a minute. That is, the projection material (mixed powder) 35 in the tank 32 is injected from the nozzle 33a at the tip of the metal tube 33 by the compressed gas 34, and the inner ring, the outer ring, and the rollers (the inner ring is shown in FIG. 2) The surface was coated with a rust-proof coating.

  The mixing ratio of the zinc powder and the tin powder in the mixed powder was set so that the zinc powder was 20 to 80% by mass (that is, the tin powder was 80 to 20% by mass). As the gas 34, air or a mixture of air and nitrogen was used. Since oxygen is contained in the gas 34 used for shot peening, a part of the mixed powder is oxidized and zinc oxide and tin oxide are generated (passivated). The amount of oxygen in the anticorrosive coating is determined by the amount of zinc oxide and tin oxide produced, and this amount of oxygen can be adjusted by the ratio (partial pressure) of air in the gas 34.

Table 1 shows the mixing ratio of zinc powder and tin powder in the mixed powder, the ratio (partial pressure) of air and nitrogen in the gas 34, and the amount of oxygen in the anticorrosive coating. For the measurement of the oxygen amount, a secondary electron microscope (SEM) “JSM-5610” manufactured by JEOL Ltd. and an energy dispersive X-ray spectrometer “Phoenix / Falcon” manufactured by EDAX of the United States attached thereto are used. Using. The sample was irradiated with an electron beam emitted from a tungsten filament to which an acceleration voltage of 15 kV was applied, and the generated fluorescent X-rays were analyzed to measure the amounts of zinc, tin, and oxygen contained in the sample. The measured value was corrected by the ZAF method. Other measurement conditions are as follows.
Field of view (magnification): 300 times Extraction angle: 30 °
Tilt angle: 0 °
Integration time: 60 seconds

Next, a method for evaluating rust resistance will be described. The self-aligning roller bearing coated with a rust preventive coating was left in an environment of a temperature of 80 ° C. and a humidity of 95%, and the state of rusting was visually observed. And the situation of rusting was ranked as follows.
When there is no rusting at "0 rank", when white rust consisting of zinc oxide or tin oxide is found in less than 20% of the entire surface, it is "1 rank", white rust is 20% or more of the entire surface and 100% The case where it was seen in the following part was set to "2 ranks". In addition, when the rust further progresses and the red rust made of iron oxide is found in less than 20% of the entire surface, “3 rank”, the case where the red rust is found in the entire surface of 20% or more and less than 50% The case where “4 ranks” and red rust were found in the portion of 50% or more and 100% or less of the entire surface was designated as “5 ranks”. The case where red rust further progressed and the layered rust was raised was designated as “6 rank”, and the case where damage such as perforation or breakage occurred was designated as “7 rank”.

  The results are shown in the graph of FIG. In Examples 1 to 3, since the oxygen content of the rust preventive coating is 5% by mass or more, excellent rust preventive properties are exhibited over a long period of time due to the self-sacrificial anticorrosive action of zinc. On the other hand, in Comparative Examples 1 and 2, since the oxygen content of the anticorrosive film is less than 5% by mass, the effect of passivating does not appear, and the oxidation rate of zinc is fast and the antirust property is low. As a result, red rust occurred in a short time of 300 to 400 hours.

It is a fragmentary longitudinal cross-section which shows the structure of the self-aligning roller bearing which is one Embodiment of the rolling device which concerns on this invention. It is explanatory drawing of a shot peening apparatus. It is a graph which shows the evaluation result of rust prevention property.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 1a Raceway surface 2 Outer ring 2a Raceway surface 3 Rolling element 3a Rolling surface

Claims (8)

  A first metal having a redox potential of less than −0.44 V, a second metal having a redox potential of −0.43 V or more, an oxide of the first metal, and an oxidation of the second metal. A rust preventive treatment method comprising coating a surface of a steel material with a rust preventive film containing at least one of the objects.   The rust-proofing method according to claim 1, wherein the rust-proof coating is applied by shot peening in which the first metal powder and the second metal powder are sprayed onto the surface of the steel material.   The rust preventive treatment method according to claim 1 or 2, wherein the oxygen content in the rust preventive coating is 5 mass% or more.   The rust preventive treatment method according to claim 3, wherein the oxygen amount is a value obtained by correcting a measured value obtained by fluorescent X-ray spectroscopy by a ZAF method. An inner member having a raceway surface on the outer surface, an outer member having a raceway surface opposite to the raceway surface of the inner member, and arranged on the outer side of the inner member, and rolling between the both raceway surfaces In a rolling device comprising a plurality of freely arranged rolling elements,
At least one of the inner member, the outer member, and the rolling element has a first metal having an oxidation-reduction potential of less than −0.44 V and an oxidation-reduction potential on at least a part of the surface thereof. A rust-proof coating containing a second metal of −0.43 V or more and at least one of an oxide of the first metal and an oxide of the second metal is provided. Rolling device.   The rolling according to claim 5, wherein the rust preventive coating is formed by shot peening in which the first metal powder and the second metal powder are sprayed onto the surface. apparatus.   The rolling device according to claim 5 or 6, wherein the amount of oxygen in the antirust coating is 5% by mass or more.   The rolling device according to claim 7, wherein the oxygen amount is a value obtained by correcting a measurement value obtained by X-ray fluorescence spectrometry using a ZAF method.

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