阅读说明：本技术 防电蚀滚动轴承 (Anti-electric erosion rolling bearing ) 是由 田中裕 于 2019-09-24 设计创作，主要内容包括：一种防电蚀滚动轴承,具备：内圈(1)、外圈(2)、滚动体(3)以及在内圈(1)的内周面、外圈(2)的外周面上的电绝缘性的陶瓷喷涂被膜(4)；通过将粒径5～60μm且平均粒径30～60μm的氧化铝粒子作为喷涂材料的主成分设置陶瓷喷涂被膜(4),并且用平均粒径5～40μm的二氧化硅、氧化钇、二氧化钛或者氧化锆等熔点比氧化铝低的金属氧化物的玻璃熔体的规定量填充氧化铝粒子间的空孔,从而使陶瓷喷涂被膜(4)致密化。(An anti-electrolytic-corrosion rolling bearing is provided with: an inner ring (1), an outer ring (2), rolling elements (3), and an electrically insulating ceramic spray coating (4) on the inner circumferential surface of the inner ring (1) and the outer circumferential surface of the outer ring (2); a ceramic spray coating (4) is provided by using alumina particles having a particle diameter of 5 to 60 [ mu ] m and an average particle diameter of 30 to 60 [ mu ] m as a main component of a spray material, and pores between the alumina particles are filled with a predetermined amount of a glass melt of a metal oxide having a melting point lower than that of alumina, such as silica, yttria, titania, zirconia, or the like, having an average particle diameter of 5 to 40 [ mu ] m, thereby densifying the ceramic spray coating (4).)

1. An anti-electrolytic-corrosion rolling bearing comprising an inner ring, an outer ring, a plurality of rolling elements rotatably interposed between raceway surfaces of the inner and outer rings, and an electrically insulating ceramic sprayed film on an inner peripheral surface of the inner ring or an outer peripheral surface of the outer ring or both,

the anti-electrolytic corrosion rolling bearing is formed by providing the ceramic spray coating by using alumina particles with the particle size of 5-60 mu m and the average particle size of 30-60 mu m as the main component of a spray material, and filling the pores among the alumina particles with a glass melt of a metal oxide with the average particle size of 5-40 mu m, thereby densifying the ceramic spray coating.

2. The anti-electrolytic corrosion rolling bearing according to claim 1, wherein the ceramic sprayed film contains 1.5 to 5.0 mass% of a glass melt of a metal oxide in 100 mass% of the composition.

3. The anti-electrolytic corrosion rolling bearing according to claim 1 or 2, wherein the metal oxide is a metal oxide having a lower melting point than alumina.

4. The anti-electrolytic corrosion rolling bearing according to claim 3, wherein the metal oxide is 1 or more metal oxides selected from silica, yttria, titania, and zirconia.

5. The anti-electrolytic corrosion rolling bearing according to claim 4, wherein the metal oxide is silica, which is combined with alumina to densify the ceramic sprayed coating.

6. The anti-electrolytic corrosion rolling bearing according to any one of claims 1 to 5, wherein the ceramic sprayed film has a film forming property capable of being sprayed at a spraying distance of 140 to 170mm and is densified so that an insulation breakdown voltage is 6kV or more.

Technical Field

The present invention relates to an anti-electrolytic rolling bearing which supports a rotating shaft, such as a rotating shaft of an electric motor or a rotating shaft of a generator, which is likely to flow a current, in an insulated manner, thereby preventing electrolytic corrosion of a current path portion.

Background

In general, an anti-electrolytic rolling bearing that supports a rotating shaft of an electric motor, a rotating shaft of a generator, or the like has corrosion resistance and electrical insulation properties by a sprayed coating formed by spraying hard particles or powder such as ceramics on a surface of a main part of a component made of metal such as steel.

The ceramic spray coating film has voids such as voids, gaps, and cavities (pores) generated during the formation of the coating film, and since a part of the voids becomes a communicating pore and gas or liquid in contact with the outer side of the spray coating film may permeate into the interior of the spray coating film, the corrosion resistance and the electrical insulation of the spray coating film may be lowered.

In order to improve the insulating performance of the bearing having the sprayed coating formed thereon, it is effective to form the sprayed coating densely so that gas or liquid cannot penetrate into the sprayed coating.

However, most of alumina spraying is atmospheric pressure plasma spraying which is generally performed in the atmosphere, and in order to form a spray coating film densely, it is desirable to form a film of a powdery spray material in a state of being almost melted by making the distance between the spray nozzle and the workpiece as close as possible.

However, in the spraying process using a bearing as a workpiece, if the spray jet is too close to the workpiece, the temperature of the quenched and tempered workpiece may rise and tempering may occur. In order to prevent such a tempering, the distance is adjusted so that the spray jet ports are appropriately close to the workpiece, but such an adjustment is not easy.

When the powder spray material is melted to form a film, microcracks are generated in the process of heat release at room temperature in the high-temperature spray film, which easily causes a decrease in the dielectric breakdown voltage.

Therefore, in the conventional alumina spray coating process, a dense spray coating having a high dielectric breakdown voltage as high as possible is formed by making the spray distance close to a level at which tempering does not occur, or by adjusting the particle diameter of the spray material of the powder.

For example, patent document 1 describes that an electroerosion preventing insulated rolling bearing having a small variation in insulation resistance value is obtained by adding 1 mass% or less of a metal oxide such as titanium dioxide, silicon dioxide, or chromium oxide to a spray material containing 97 mass% of alumina having a particle diameter of 10 to 50 μm and an average particle diameter of 15 to 25 μm, spraying the mixture, and sealing the mixture with a resin to form a sprayed layer having a porosity of 2 to 6%. This document describes that if too much metal oxide, which is generally hydrophilic, is added, the dielectric breakdown voltage decreases (patent document 1).

It is also known that the main portions of the inner and outer races are made of fused alumina (Al)₂O₃) The anti-electrolytic-corrosion rolling bearing with an insulating layer comprising the sprayed coating of (1) wherein the insulating layer contains 10 to 40 mass% of silicon dioxide (SiO)₂) The number of voids formed in the insulating layer can be reduced to improve the insulating property (see [0014 ] of patent document 2)]Segments, etc.).

Further, there is known an insulated rolling bearing in which a ceramic sprayed layer containing 97 mass% or more of alumina having a particle size of 10 to 50 μm and an average particle size of 15 to 25 μm contains 0.5 to 2.5 mass% of zirconia, thereby providing a sprayed layer capable of securing a desired insulation property and appearance without color unevenness (patent document 3).

Documents of the prior art

Patent document

Patent document 1 Japanese patent No. 5025190

Patent document 2 Japanese patent laid-open publication No. 2016-14413

Patent document 3, Japanese patent laid-open No. 2007-198519

Disclosure of Invention

However, in the conventional alumina spray coating process, in order to efficiently form a dense spray coating, the spray distance is adjusted to be close to the limit of no thermal influence when the spray coating is performed, and it is necessary to frequently interrupt or weaken the spray coating to secure a cooling time. Therefore, it takes a considerable time to form a dense film by spraying, resulting in a decrease in manufacturing efficiency and an increase in manufacturing cost.

Further, in order to perform spraying under optimum conditions by adjusting a short spraying distance, a particle diameter of powder, and the like within a limit where tempering due to spraying does not occur, trial and error must be repeated to avoid the risk of occurrence of tempering and microcracking, and even then tempering and microcracking may occur due to slight differences in spraying conditions.

However, in an electric corrosion prevention rolling bearing used for an electric motor or the like, a return current or a motor shaft current may flow, and if a high-voltage current exceeding an insulation breakdown voltage flows, an insulation layer is broken and the electric corrosion prevention property is irreversibly lost. In addition, it is also necessary to sufficiently increase the insulation breakdown voltage of such a rolling bearing in advance in consideration of safety.

As described in patent document 1, if the particle diameter of alumina, which is the main component of the spray coating, is set to an average particle diameter of 15 to 25 μm at the time of spraying, the porosity is reduced to some extent, but it is difficult to block the pores inside the spray coating.

Further, since the metal oxide such as titanium dioxide, silicon dioxide, or chromium oxide described in patent document 1 has high hydrophilicity and tends to vary in insulation resistance value and become unstable, the content thereof is limited to 1 wt% or less, preferably 0.5 wt% or less, and more preferably 0.2 wt% or less, but a stable and excellent insulation property having a dielectric breakdown voltage of 6kV or more is not obtained.

In addition, the ceramic spray coating described in patent document 3 uses alumina having a particle size of 10 to 50 μm and an average particle size of 15 to 25 μm and 0.5 to 2.5 mass% of zirconia in order to improve the adhesion efficiency of alumina, but it is difficult to fill the gaps between alumina particles having a small particle size with zirconia having an unspecified particle size, and in this case, a high dielectric breakdown voltage exceeding 6kV is not obtained.

Further, even when fused alumina is prepared by adding 10 to 40 mass% of silica to alumina as described in patent document 2, it is difficult to stably exhibit excellent insulation performance such as an insulation breakdown voltage of 6kV or more (fig. 2, paragraph [0024] of patent document 2).

The reason for this is presumably that if the pores are filled with a large amount of silica, microcracks are likely to form due to the difference in thermal expansion between the glass phase and alumina, and the microcracks allow gas and liquid to permeate from the outside to the inside of the sprayed coating.

Accordingly, an object of the present invention is to solve the above-described problems and to provide an anti-electrolytic rolling bearing having a dense spray coating film up to the inside, a uniform spray coating film without unevenness, and excellent insulation properties such as a sealing treatment and an insulation breakdown voltage of 6.0kV or more.

Further, an anti-electrolytic corrosion rolling bearing is provided with a spray coating having a good film forming property capable of being formed at a predetermined spray distance or more without being heated by tempering of a base material of the rolling bearing, and the spray coating is dense and has excellent insulation properties.

In order to solve the above problems, the present invention provides an electric corrosion prevention rolling bearing comprising an inner ring, an outer ring, a plurality of rolling elements rotatably interposed between raceway surfaces of the inner and outer rings, and an electrically insulating ceramic sprayed coating on an inner peripheral surface of the inner ring or an outer peripheral surface of the outer ring or both, wherein the ceramic sprayed coating is formed by using alumina particles having a particle diameter of 5 to 60 μm and an average particle diameter of 30 to 60 μm as a main component of a spraying material, and pores between the alumina particles are filled with a glass melt of a metal oxide having an average particle diameter of 5 to 40 μm, thereby densifying the ceramic sprayed coating.

The inventors of the present application found that: the anti-electrolytic-corrosion rolling bearing of the present invention configured as described above is formed with a ceramic sprayed coating containing alumina particles having a particle size of 5 to 60 μm and an average particle size of 30 to 60 μm as a main component of a spraying material, whereby latent pores and the like having no openings on the surface are filled with a glass melt of a metal oxide having an average particle size of 5 to 40 μm, thereby densifying the ceramic sprayed coating.

It should be noted that, in order to prevent liquid from penetrating from the surface, it is preferable to seal not only the pores latent in the ceramic spray coating but also the pores opened in the surface of the ceramic spray coating by a sealing treatment which is usually performed. Such a ceramic sprayed film is filled with a glassy metal oxide from the inside to the surface of the sprayed film, the opening of the surface is sealed with a sealing agent, and the sprayed film is provided in a dense state with high insulation from the inside to the surface.

The anti-electric erosion rolling bearing of the present invention having a dense electrically insulating ceramic sprayed coating with high insulation properties has excellent insulation properties with no unevenness and has an insulation breakdown voltage of 6.0kV or more.

In order to seal the pores sufficiently, a glass melt containing more than 1.0 mass% and not more than 5.0 mass%, for example, 1.5 to 5.0 mass% of a metal oxide having an average particle diameter of 5 to 40 μm is preferably contained in 100 mass% of the composition of the ceramic spray coating film.

When the amount of the metal oxide having a melting point lower than that of alumina is small such that the amount is less than 1.5 mass% based on alumina having a predetermined particle diameter, some pores in the spray coating are left without being sealed, and the result of measuring the dielectric breakdown voltage is unstable.

Further, if the amount of the glassy metal oxide is more than 5.0 mass% with respect to the alumina, the glassy metal oxide in an amount necessary for insulation spreads inside the sprayed coating, and microcracks are likely to occur due to a difference in thermal expansion between the glassy portion and the alumina, and the measurement result of the dielectric breakdown voltage is unstable, and the average value of the dielectric breakdown voltage may not reach the desired 6 kV.

Further, since the melting point of alumina is lowered and melting is facilitated by adding a certain amount of metal oxide to alumina, even if the base material of the bearing is sprayed with a distance of such a degree that tempering is not entered, a film can be formed by a sufficiently melted spray material, and a dense ceramic spray coating film can be provided.

As the metal oxide preferably used in the present invention, a metal oxide having high insulation properties and a melting point lower than that of alumina is preferably used, and 1 or more selected from silica, yttria, titania, and zirconia which are easily vitrified at the time of film formation are preferably used.

In particular, when the metal oxide is silica, the silica is combined with alumina to form mullite, and the ceramic sprayed film can be densified.

The ceramic spray coating film preferably has good film forming properties enabling spray coating at a spray distance of 140 to 170mm and is densified so that the dielectric breakdown voltage is 6.0kV or more.

The ceramic spray coating film has a film forming property enabling spraying at a predetermined spraying distance or more, and thus the ceramic spray coating film can be formed at a distance not heated to temper the rolling bearing, and therefore, it is not necessary to sufficiently secure a cooling time during spraying, and therefore, a dense film can be efficiently formed by continuous spraying, and a ceramic spray coating with high production efficiency can be obtained.

The ceramic sprayed coating formed in this way becomes a ceramic sprayed coating having an insulation breakdown voltage of 6kV or more, and becomes an anti-electrolytic-corrosion rolling bearing having stable and excellent desired insulation performance.

The invention has the following advantages: since the ceramic sprayed coating is provided using alumina particles having a predetermined particle diameter as a main component of the spray material and the anti-electrolytic rolling bearing having the sprayed coating in which pores between the alumina particles are filled with a glass melt of a metal oxide having a predetermined average particle diameter is manufactured, the anti-electrolytic rolling bearing having the sprayed coating which is dense even inside and has a uniform insulating property without unevenness and having such an extremely excellent insulating property that the insulation breakdown voltage is 6.0kV or more by the sealing treatment is provided.

The ceramic spray coating film also has the following advantages: the coating has a film forming property capable of being sprayed efficiently over a predetermined spraying distance, and can provide an anti-electrolytic rolling bearing having a dense coating film without heating to temper the rolling bearing.

Drawings

Fig. 1 is a sectional view of a main portion of an electric corrosion prevention rolling bearing of the embodiment.

FIG. 2 is a graph showing the relationship between the amount of silica added and the dielectric breakdown voltage in examples 1 to 6, comparative examples 1 to 4 and reference examples 1 to 9.

FIG. 3 is a SEM photograph of the ceramic spray coating film of example 1.

FIG. 4 is a SEM photograph of the ceramic spray coating film of comparative example 1.

FIG. 5 is a graph showing the insulation breakdown voltages of examples 4, 7 and 8 and comparative examples 1, 5 and 6.

FIG. 6 is a graph showing the dielectric breakdown voltage in terms of the spray distance in example 1 and comparative examples 1 and 2.

FIG. 7 is a graph showing the relationship between the spray distance and the insulation breakdown voltage in examples 1, 9 and 10 and comparative example 7.

FIG. 8 is a graph showing the relationship between the spray time and the film formation amount in reference example 1 and example 1.

Detailed Description

As shown in fig. 1, an anti-electrolytic-corrosion rolling bearing according to an embodiment includes: an inner ring 1, an outer ring 2, a plurality of rolling elements (balls) 3 rotatably interposed between these rolling surfaces, and an electrically insulating ceramic sprayed film 4 on the inner peripheral surface of the inner ring 1 and the outer peripheral surface of the outer ring 2. Reference numeral 5 in the drawings denotes a retainer. The ceramic spray coating 4 is shown to be provided on both the inner ring 1 and the outer ring 2, but may be provided on either one.

The ceramic spray coating 4 in the anti-electrolytic corrosion rolling bearing of the embodiment is formed by filling pores between alumina particles with a glass melt of a metal oxide having an average particle diameter of 5 to 40 [ mu ] m, preferably an average particle diameter of less than 40 [ mu ] m, by using the alumina particles having an average particle diameter of 40.0 [ mu ] m or less as a main component of a spray material, thereby densifying the ceramic spray coating 4.

The alumina has a particle size of 5 to 60 μm and an average particle size of 30 to 60 μm. If alumina having a large particle diameter exceeding such a numerical range or an average particle diameter is used, the number of pores and the pore diameter become large, and therefore, it may be impossible to reliably fill the glassy metal oxide without a gap, and it may be difficult to form a sufficiently dense spray coating. In order to perform spray coating with high adhesion efficiency, the alumina preferably has a particle size of 5 μm or more and an average particle size of 30 μm or more.

The metal oxide as an additive component has an average particle diameter of 5 to 40 μm and a melting point lower than that of the alumina. Since the metal oxide having an average particle diameter of less than 5 μm is dispersed too finely, it is difficult to form a small glassy mass by gathering the metal oxide so as to sufficiently fill the pores in the gaps around the alumina particles. In addition, it is difficult for the metal oxide having a large particle diameter having an average particle diameter of more than 40 μm to flow into the small pores, and it is difficult to sufficiently densify the ceramic spray coating.

As an example of the metal oxide, in order to form a ceramic sprayed film stably having a desired dielectric breakdown voltage, it is preferable to use a material selected from silicon dioxide (SiO)₂) Yttrium oxide (Y)₂O₃) Titanium dioxide (TiO)₂) And zirconium oxide (ZrO)₂) 1 or more kinds of metal oxides.

Such a metal oxide which is easily vitrified, such as silica, yttria, titania, zirconia, or the like, has a function of filling pores formed by alumina by itself being vitrified at the time of film formation.

By adding a predetermined amount of such a metal oxide to alumina as a main component, a ceramic spray coating having a dense inner portion to surface can be obtained. It is considered that if the number of voids is large due to insufficient densification, the number of voids becomes a factor of variation in insulation breakdown voltage, but in the present invention, almost all of the voids are filled with the metal oxide and disappear, and thus variation in insulation performance is also reduced.

The composition of the spray material may be, for example, 95.0 to 98.5 mass% of alumina and 1.5 to 5.0 mass% of metal oxide, and for example, if the content of alumina is 97.0 mass% or more and the content of metal oxide such as zirconia is 1.5 to 2.5 mass%, strength and toughness can be improved together with insulation. If necessary, a known metal oxide may be further added.

The desired effect can be expected if the metal oxide is contained in an amount exceeding 1.5 mass% in the value of the dielectric breakdown voltage, but the effect tends to be lowered if the amount is 5.0 mass% or more. The reason for this is considered to be as follows: if the metal oxide is too much, the glass phase of the filled pores after spraying becomes too much, and microcracks are likely to occur due to a difference in thermal expansion between the glass phase and alumina, and as a result, the breakdown voltage is lowered. The measurement of the insulation breakdown voltage mentioned in the present invention can be performed based on JISK 6911.

As the spraying method, a known plasma spraying method such as an atmospheric pressure plasma spraying method can be used. Further, known spraying methods such as powder flame spraying and high-speed gas flame spraying can be used.

The apparatus for forming the ceramic spray coating film is an apparatus which has a spray gun as a spray mechanism and sprays (ejects) the spray material from an ejection port, and for example, a known spray robot system may be used. The spraying distance is a distance between the spraying nozzle and the workpiece.

The ceramic spray coating film thus formed is preferably thick in thickness according to the required insulation property, and is preferably made to have a film thickness of 250 μm or more, for example.

Examples

Examples 1 to 6 and comparative examples 1 to 4

After degreasing and cleaning as a pretreatment, the outer ring and the inner ring of the deep groove ball bearing made of bearing steel are subjected to masking treatment and blast treatment except the outer peripheral surface of the outer ring and the inner peripheral surface of the inner ring (including both end surfaces of the inner peripheral surface and the outer peripheral surface), and these treated surfaces are subjected to atmospheric plasma spraying to form a spray coating film.

The powdery spray coating materials used in examples 1 to 6, comparative examples 1 to 4, and reference examples 1 to 9 were prepared as follows: in the presence of high purity alumina powder (Al)₂O₃) An appropriate amount of gray alumina powder (particle diameter 8 to 38 μm, average particle diameter about 32 μm) for coloring was mixed (particle diameter 8 to 38 μm, average particle diameter about 32 μm), and further specified in Table 1 belowSilica (SiO) having an average particle diameter of 10.0 μm was added in the mixing ratio shown₂)。

Using this spray material, an alumina spray coating (ceramic spray coating) having a spray coating layer thickness of 560 μm was formed by atmospheric pressure plasma spraying at a spray distance of 150mm by a conventional method, and further subjected to a sealing treatment using an epoxy resin-based sealing agent, followed by grinding to produce an outer ring and an inner ring, which were assembled to produce rolling bearings of examples 1 to 6, comparative examples 1 to 4, and reference examples 1 to 9.

Next, the insulation breakdown voltage measurements were performed, and the results are collectively shown in fig. 2. The sprayed coatings of the inner and outer races formed in example 1 and comparative example 1 were observed by a Scanning Electron Microscope (SEM), and are shown in fig. 3 and 4, respectively. The insulation breakdown voltage was measured as follows: the outer ring on which the sprayed film was formed was fixed to a test jig, and the voltage was increased from the initial voltage of 2.0kV by a step (step) of 0.2kV, and the voltage at which breakdown occurred was measured.

Further, insulation breakdown voltage measurements were performed for example 4 and comparative example 1, and the results are shown in fig. 5.

[ Table 1]

[ reference examples 1 to 9]

In examples 1 and 3 to 6 and comparative examples 1 to 4, alumina powder having a particle diameter of 98 μm or less (#320) was used in place of high-purity alumina powder (Al)₂O₃Particle size of 8 to 38 μm) and the amount of silica added shown in table 1 were used, and a spray coating was formed on the inner and outer rings of the rolling bearings of reference examples 1 to 9 in the same manner as in example 1.

Then, the dielectric breakdown voltage of the sprayed coating was measured, and the relationship between the amount of silica added and the dielectric breakdown voltage (kV) was also shown by a chain line in fig. 2.

The relationship between the amount of silicon dioxide added and the dielectric breakdown voltage shown by the solid line in FIG. 2Known as silicon dioxide (SiO)₂) The amount of (2) is more than 1.0 mass% (comparative example 2), and the insulation breakdown voltage exceeds 6kV from the addition of 1.5 mass% (example 1) to a high level, and the insulation breakdown voltage of 6kV or more is maintained including "variation" shown by the vertical line of the I-shape in the figure until the amount of addition is 5 mass% (example 6), but it is found that the amount of addition above tends to decrease to less than 6 kV.

Therefore, it is found that the desired results of the present invention can be obtained when the content of silica as the metal oxide is 1.5 to 5.0 mass%.

It is also understood from the results shown by the chain line in FIG. 2 that, as in the conventional reference example, when the particle size of alumina is larger than 60 μm, the effect of adding silica is considered to be exhibited to some extent, but the measured average value of the dielectric breakdown voltage is lowered, and the dielectric breakdown voltage exceeding 5kV is not obtained even if the blending ratio is adjusted.

Further, from the SEM photographs shown in fig. 3 and 4, it is understood that the spray coating of comparative example 1 in which no silica was blended at all had many pores and was open at the surface (fig. 4), and the spray coating of example 1 in which a predetermined amount of silica was added had almost no open at the surface and was dense (fig. 3).

Examples 7 to 10 and comparative examples 5 to 7

In example 4, 3 mass% of zirconium oxide (ZrO) was added in place of silicon dioxide as the metal oxide₂) Except for the case of (1) (example 7) or the case of not adding any additive (comparative example 5), a sprayed coating of a rolling bearing was produced in the same manner as in example 4, and the insulation breakdown voltage of the sprayed coating was measured, and the results thereof are shown in fig. 5.

In example 4, 3 mass% of yttrium oxide (Y) was added in place of the metal oxide, i.e., silicon dioxide₂O₃) Except for the case (example 8) or the case (comparative example 6) where no coating was added, a sprayed coating of a rolling bearing was produced in the same manner as in example 4, the insulation breakdown voltage of the sprayed coating was measured, and the insulation breakdown voltage was measuredThe results are shown in FIG. 5.

From the results shown in fig. 5, it is understood that when a predetermined metal oxide such as silica, zirconia, or yttria is added in an amount of 3 mass%, even if any one of the metal oxides is added, high insulation properties having a dielectric breakdown voltage of more than 6kV can be obtained.

In the above examples, the gray alumina was added, and therefore, a small amount of titanium dioxide was contained, and even then, the dielectric breakdown voltage was increased at a high level. From this, it is understood that the effect of the present invention is not impaired even when a metal oxide other than the above-described predetermined metal oxide is added.

The kind, particle size, and amount of the metal oxide to be added to the spray coating material of each example are shown in table 2 below for examples 1, 9, and 10 and comparative example 7.

[ Table 2]

[ evaluation of relationship between spray distance and dielectric breakdown Voltage ]

(evaluation 1)

Rolling bearings having ceramic sprayed coatings were produced under the same conditions as in examples 1 and comparative examples 1 and 2 except that the spraying distances were set to 160mm, 150mm and 140mm, and the insulation breakdown voltages of the ceramic sprayed coatings were measured, and the results are shown in fig. 6.

As is clear from the results shown in FIG. 6, SiO was not added₂Comparative example 1 or adding 1.0 mass% of SiO₂In comparative example 2, the dielectric breakdown voltage decreased as the spray distance increased, but 1.5 mass% of SiO was added₂In example 1, the dielectric breakdown voltage was not lowered even when the spray distance was increased, and a high level exceeding 6kV was maintained.

From this, it was found that the ceramic spray coating film formed by the spray material used in example 1 has a small "variation" in the dielectric breakdown voltage and stable insulation characteristics even when the spray distance is changed to 140mm or more.

(evaluation 2)

In examples 1, 9, 10 and comparative example 7, in the case of spraying the spray materials of the respective examples containing the predetermined metal oxides shown in table 2, the spray distance was changed stepwise every 10mm within the range of 120 to 180mm, and the spraying was performed under the same conditions as in example 1, thereby producing a rolling bearing having a ceramic spray coating film, and the insulation breakdown voltage of the ceramic spray coating film formed on the surface of the member was measured, and the results are shown in fig. 7. The results of the dielectric breakdown voltage for spray distances of less than 140mm or greater than 170mm are shown as thin lines in the figure.

From the results shown in FIG. 7, it is understood that in examples 1, 9 and 10 in which a predetermined amount (1.5 mass%) of a metal oxide composed of silica, yttria and zirconia was mixed and the average particle diameter was 10 μm, the dielectric breakdown voltage was 6kV or more in the range of the spraying distance 140 to 170mm, but in comparative example 7 in which the average particle diameter of silica was 100 μm, the dielectric breakdown voltage was less than 6 kV.

[ evaluation of relationship between spray time and film formation amount ]

With respect to example 1 and conventional example (reference example 1), the relationship between the spray time including the cooling time and the film formation amount when necessary was analyzed while the spray distance was set to 160mm in the spray step of the example and 130mm in the spray step of the conventional example (reference example 1), and is shown in fig. 8.

As is clear from the results of fig. 8, in the conventional example (reference example 1), the spray distance was set to be approximately 130mm in order to form a spray coating film densely, but since 4 times of cooling time were required in order to temper the base material without heating at the time of spray coating, about 700 seconds were required for 570 μm film formation.

On the other hand, in example 1, since the spraying distance was an appropriate distance (160mm), the influence of heating for tempering the base material was not received, and it was not necessary to take a long time for cooling the base material, and the processing time could be shortened to about 1/5 compared to the conventional process.

Industrial applicability

The anti-electrolytic-corrosion rolling bearing of the present invention has general applicability to rolling bearings for supporting a rotating shaft through which current may flow, and may be used for, for example, generators for air conditioners, electric trains, wind power generation, etc., electric motors for machine tools, etc., guide rails for linear motors, etc.

Description of the symbols

1 inner ring

2 outer ring

3 rolling element

4 spray coating capsule

5 a holder.