JPH06147231A - Electric insulating bearing - Google Patents

Abstract

PURPOSE:To obtain an electric insulating bearing with the structure which is excellent in stability of measurement and resistance for shock, easy in installation and capable of estimating its insulation, and has insulating materials hard to damage. CONSTITUTION:An electric insulating bearing is composed of an outer ring 3, an inner ring 5, and rolling elements 6 arranged therebetween. The outer ring 3 is integrally composed of an outer ring main body 11 which has a raceway track 11a for rolling the rolling elements 6, an insulating thin film 12 having a thickness of 0.1 to 2.0mm made of alloy material of polyamide and polyphenylene sulfide for coating a portion of the outer ring main body 11 to be installed in a housing 2, and a thin metal plate 13 formed on an outer surface of the insulating thin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing having excellent electric insulation.

[0002]

2. Description of the Related Art A bearing in which a rolling element is interposed between an outer ring and an inner ring is generally known. In rotating electrical machines, if the rotary bearing of the main motor is not electrically insulated and shielded, shaft current flows from the main motor frame to the armature shaft through a metal bearing, damaging or burning the bearing. Easier to do. Therefore, as a technique for blocking the shaft current to prevent damage to the bearing portion of the main motor, the bearing is ceramic processed (Japanese Utility Model Laid-Open No. 60-161721 and Japanese Patent Laid-Open No. 59-103023). Japanese Patent Application No. 53-
No. 81459, Japanese Utility Model Laid-Open No. 59-173467) and a polymer insulating material interposed in a bearing outer ring (Japanese Utility Model Laid-Open No. 54-105408, Japanese Utility Model Laid-Open No. 58-33820).
(See Japanese Patent Publication).

An insulating bearing having an insulating coating made of glass fiber-containing polyphenylene sulfide (PPS) or glass fiber-containing nylon (Japanese Patent Laid-Open No. 3-27781).
No. 8 and Japanese Utility Model Laid-Open No. 3-122222) are proposed.

Further, an electrically insulating bearing is formed by integrally forming an outer ring main body, an insulating thin film covering the outer peripheral portion of the outer ring main body, and a thin metal plate provided on the outer surface of the insulating thin film (Japanese Patent Application Laid-Open No. Hei 3 (1998) -304). Japanese Patent Laid-Open No. 103615) is proposed.

[0005]

Generally, a bearing of a main electric motor is required to have high dimensional accuracy. However, a bearing provided with an insulating member cannot obtain the dimensional accuracy of the bearing itself, and therefore the bearing is assembled to the main electric motor housing. As a result, the assembly dimensional accuracy becomes low. It is the above-mentioned ceramic-processed bearing that has improved this dimensional accuracy deterioration, but the brittleness of the ceramic itself cannot be wiped off, and the main motor housing and bearing cannot be wiped unless assembled. Insulation between and cannot be evaluated. Further, when a polymer insulating material is used, the dimensional accuracy of the polymer member itself is low. Furthermore, from the viewpoint of reducing the amount of strain under axial load, it is made thinner, so
Ceramic or polymer material can be damaged during installation or removal. Further, nylon has a drawback that its dimensions are likely to change due to moisture absorption, and PPS lacks impact resistance when an external force such as vibration is applied. Furthermore, it is impossible to obtain an electrically insulated bearing having excellent dimensional stability simply by integrally molding the outer ring body, the insulating thin film and the thin metal plate. The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide excellent dimensional stability and impact resistance, easy attachment, and easy evaluation of insulating property, and an insulating material. The purpose of the present invention is to provide an electrically insulated bearing having a structure that is not easily damaged.

[0006]

In order to achieve the above object, the gist of the present invention is an electrically insulated bearing having a rolling element interposed between an outer ring and an inner ring, wherein the outer ring has a rolling element. A metal outer ring body having a rolling track, an insulating thin film having a thickness of 0.1 to 2.0 mm and made of an alloyed material of polyamide and PPS for covering a portion of the outer ring body to be attached to a housing, and An electrically insulating bearing is characterized by being integrally molded with a thin metal plate provided on the outer surface of an insulating thin film.

[0007]

In the bearing according to the present invention, since the outer ring is integrally formed with the outer ring body, the insulating thin film and the thin metal plate, the outer ring itself has an insulating property for electrically insulating from the housing side. The insulation can be evaluated by measuring the electric resistance between the outer ring body and the thin metal plate before the bearing is assembled to the housing.
Further, since it is not necessary to provide an extra interposition for electrical insulation between the bearing and the housing, the bearing can be easily assembled and the dimensional accuracy of the bearing can be easily increased. is there. In this case, since the insulating thin film itself has a small thickness, the strain amount due to the load is small, and the influence on the dimensional accuracy can be ignored. Further, the dimensions of the outer ring can be easily adjusted by processing the thin metal plate.
Further, the thin metal plate protects the insulating thin film from being damaged when it is attached to the housing, and also prevents the insulating thin film from being broken by a load during use. Since the insulating thin film is made of polyamide and PPS, it has excellent dimensional stability and impact resistance.
Also, by setting the thickness of this thin film to be 0.1 mm or more, desired electrical insulation can be obtained.
When the thickness is less than or equal to mm, the strain amount due to the load during use can be suppressed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an electrically insulated bearing 1 mounted on a main motor housing 2. This electrically insulated bearing 1
Is a plurality of rolling elements 6 interposed between an outer ring 3 fixed to the housing 2 and an inner ring 5 to which the armature shaft 4 is fitted. As shown in an enlarged scale in FIG. 2, the outer ring 3 includes an outer ring body 11, an insulating thin film 12 that covers an outer peripheral portion of the outer ring body 11, and a thin metal plate 13 provided on the outer surface of the insulating thin film 12. Is integrally molded. That is,
The outer race body 11 is made of metal and has conductivity, and has the raceway 11a of the rolling element 6 on its inner peripheral portion. The insulating thin film 12 is for electrically insulating the outer race body 11 and the housing 2 from each other, and is 100 parts by weight of an alloy resin of nylon MXD6 and PPS and a glass fiber 50.
It is a polymeric elastic material consisting of parts by weight. The insulating thin film covers a portion of the outer race body 11 extending from the outer peripheral surface 11b to the side surface 11c. The thin metal plate 13 is fixed to the outer surface of the insulating thin film 12 so as not to directly touch the outer ring body 11. When the outer diameter of the outer ring 3 is about 170 mm, the thickness of the insulating thin film 12 is preferably 0.1 to 2.0 mm, the electric resistance is 100 MΩ or more, and the thickness of the thin metal plate is preferably about 1.0 mm.

On the other hand, the inner ring 5 has a raceway 5a of the rolling element 6 on its outer peripheral portion, and the rolling element 6 is held by a cage 7.
The inner ring 5, the rolling element 6, and the cage 7 are all made of metal and have conductivity.

Next, a method of manufacturing the outer ring 3 will be described. In this case, the mold shown in FIG. 3 is used. In the figure, reference numeral 15 is a lower die to which the outer ring body 11 is fitted, 16 is an upper die that covers the outer ring body 11, and 17 is a member for positioning the thin metal plate member 13A on the outer ring body 11 and coupled with the lower die 15. An outer die for forming a cavity 19 for molding the insulating thin film 12 and an outer frame 18 for fixing the outer die 17. The outer mold 17 is divided into two in the circumferential direction. The outer ring 3 is manufactured in the following order using the mold having such a configuration.

The outer peripheral surface 11b and the side surface 11C to which the insulating thin film 12 of the outer ring body 11 is fixed are sandblasted to apply an adhesive, dried at room temperature, and then dried at 323K.
Pre-heat treatment for 120 minutes is performed. As an adhesive, for example, ChemFlock # 218 manufactured by Road Far East Co., Ltd.
Can be used. 3 lower mold 15, upper mold 16, outer mold 17 and outer frame 18
It is preheated to 68K and the outer ring body 11 and the thin metal plate member 13A are assembled therein as shown in FIG. The polymeric elastic material 20 having the above composition is injected into the cavity 19 of the mold by injection molding. After cooling for a predetermined time, the mold is removed and the product is taken out. The electrically insulated bearing is constructed by assembling the rolling element 6 between the outer ring 3 and the inner ring 5 obtained as described above (finishing the outer surface of the thin-walled metal plate member 13A by polishing). Get one.

Therefore, in the bearing 1, the insulating thin film 12 of the outer ring 3 is formed of a polyamide-PPS alloy material, and the insulating ring 12 electrically insulates the outer ring 3 from the housing 2. Have. Therefore, by measuring the electric resistance between the outer ring body 11 and the thin metal plate 13 at the stage of manufacturing the outer ring 3,
Its insulating property can be evaluated. In this case, the thickness of each of the overlapping portions of the insulating thin film 12 and the thin metal plate 13 is 0.5 mm and 1.0 mm, and the electric resistance is 100 M.
It was more than Ω.

The bearing 1 is assembled to the housing 2 and the armature shaft 4. In this assembled state,
Since the insulating thin film 12 of the bearing 1 has an electric resistance of 100 MΩ or more as described above, there is no discharge from the housing 2 to the armature shaft 4 and no abnormal wear of the bearing 1 occurs. in this case,
Since the thin metal plate 13 is provided outside the insulating thin film 12 and does not come into direct contact with the outer ring body 11, it does not adversely affect the electrical insulation, and the insulating thin film 12 is only the outer peripheral surface 11b of the outer ring body 11. Not only that, but also the side surface 11c is covered, so that electrical insulation can be surely obtained.

Further, when the bearing 1 is assembled, since the outer ring 3 has an insulating property as described above, it is not necessary to provide an extra interposition between the bearing 1 and the housing 2 for electrical insulation. Therefore, the assembly of the bearing 1 is easy. Further, the dimensional accuracy of the bearing portion (positional accuracy between the housing 2 and the armature shaft 4 when the bearing 1 is assembled to the housing 2) is basically the outer diameter of the bearing 1, that is, the outer ring 3 Since the outer diameter is determined, the dimensional accuracy of the bearing portion can be increased by adjusting the dimensions of the outer ring 3 when it is manufactured. That is, if there is an extra interposer, the dimensional accuracy is reduced, but in the case of the bearing 1, the interposer is not required, so that the dimensional accuracy can be increased.
Furthermore, since the insulating thin film 12 has a small thickness,
The amount of strain due to the load during use is small, and the effect on dimensional accuracy can be ignored. Further, the thin metal plate 13 protects the insulating thin film 12 from being damaged when the bearing 1 is assembled or the bearing 1 is assembled to the housing 2, and the bearing 1 is assembled to the housing 2. It is intended to prevent the insulating thin film 12 from being destroyed by a large load during use in a found state, and it is preferable that the insulating thin film 12 is thicker than the insulating thin film 12.

Next, the dimensional change due to water absorption and the dimensional change due to oil absorption were measured for bearings coated with the polyamide-PPS alloyed resin according to the present invention and the resin according to the comparative example shown in Table 1 below. The results are shown in FIGS. 7 and 8. In addition, the measurement of the dimensional change was made by injection molding the one having the shape shown in FIG. 6 (in the figure, 31 is a resin, 32 is a bearing) and immersed in water or white kerosene for 400 hours to obtain an outer diameter of 30 mm. This was done by measuring the dimensional change of the part. Further, the temperature dependence of the flexural modulus of the resin of the present example and the resin of the comparative example in Table 1 was measured in the temperature range of 293 to 413K according to ASTM-D790. The result is shown in FIG. Table 2 shows basic physical properties of the resins shown in Table 1.

[0016]

[Table 1]

[0017]

[Table 2]

The following points are apparent from FIGS. 7 to 9 and Table 2. [Water Absorption and Oil Absorption] It can be seen from FIGS. 7 and 8 that the nylon 66 resin of Comparative Example 1 easily absorbs moisture and easily absorbs oil. In comparison, nylon MXD6-PPS alloyed resins of Examples 1 and 2 and P of Comparative Example 2 were compared.
It can be seen that the PS resin has low hygroscopicity and oil absorption and has stable dimensional accuracy. [Temperature Dependence of Bending Elastic Modulus] As shown in FIG. 9, compared with Comparative Examples 1 and 2, those according to Examples 1 and 2 have large bending elastic modulus values even in a high temperature atmosphere, and It can be seen that the strain due to the load is small. [Dimensional Change with Temperature] From Table 2, Example 1 and Example 2
It can be seen that the material according to (1) has a smaller coefficient of linear expansion than Comparative Examples 1 and 2, and has a characteristic of less dimensional change due to temperature.

[Impact resistance] From Table 2, it can be seen that those according to Examples 1 and 2 have higher impact strength and superior impact resistance than Comparative Examples 1 and 2. .

4 and 5 show another embodiment of the outer ring. In the outer ring 21 shown in FIG. 4, the insulating thin film 23 has the same width as the thin metal plate 24, and the entire side surface of the outer ring main body 22 is exposed to the outside. On the other hand, in the outer ring 25 shown in FIG. 5, the insulating thin film 27 also covers the side surface of the outer ring main body 26, and the insulating thin film 27 covers the outer peripheral surface of the outer ring main body 26 and the thickness of the portion covering the side surface. It is designed so that and are the same. In the embodiment of FIG. 5 described above, the insulating thin film and the thin metal plate are provided only in a portion that can be attached to the housing of the outer ring body, but in the other embodiments described above, the insulating thin film and the thin metal plate are also provided. The plate may be provided only at a portion to be attached to the housing of the outer ring main body as in the embodiment shown in FIG. Further, although the above embodiments relate to the rotary bearing of the main electric motor of the railway vehicle, the present invention can be applied to the bearings of other machinery and equipment as well as the undercarriage bearing of the vehicle.

[0021]

Since the electrically insulated bearing according to the present invention is constructed as described above, it has the following effects. Since it is not necessary to provide a member for electrical insulation between the bearing and the housing, the bearing can be easily assembled, the dimensional accuracy is high, the water absorption and oil absorption are low, and the dimensional change due to temperature is small. Extremely stable dimensional accuracy. It has excellent shock resistance and is resistant to mechanical shock. The electric insulation can be evaluated by the bearing alone. Since the thin metal plate protects the insulating film, the insulation life is long.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrically insulated bearing of the present invention.

FIG. 2 is an enlarged view of an outer ring portion of FIG.

FIG. 3 is a cross-sectional view showing an outer ring manufacturing apparatus.

FIG. 4 is a cross-sectional view showing another embodiment of the outer ring.

FIG. 5 is a cross-sectional view showing still another embodiment of the outer ring.

FIG. 6 is a cross-sectional view of a bearing coated with a resin for evaluating water absorption and oil absorption.

FIG. 7 is a diagram showing a dimensional change of a bearing due to water absorption.

FIG. 8 is a diagram showing a dimensional change of a bearing due to oil absorption.

FIG. 9 is a diagram showing temperature dependence of flexural modulus of a resin according to this example and a resin according to a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrically insulating bearing 2 ... Housing 3, 21, 25 ... Outer ring 4 ... Armature shaft 5 ... Inner ring 5a ... Raceway 6 ... Rolling element 11, 22, 26 ... Outer ring body 11a ... Raceway 11b ... Outer peripheral surface 11c ... Side surface 12, 23, 27 ... Insulating thin film 13, 24, 28 ... Thin metal plate

Front page continued (72) Inventor Hisao Fukunaga 3-2-15 Meiwadori, Hyogo-ku, Kobe, Hyogo Prefecture Bando Kagaku Co., Ltd. (72) Inventor Yoshiya Fuse 3-2-115, Meiwadori, Kobe, Hyogo Prefecture No. Bandou Kagaku Co., Ltd. (72) Inventor Asaki Watanabe 2-8 Mitsumachi, Kokubunji, Tokyo 38 Inside the Railway Technical Research Institute

Claims (1)

[Claims] 1. An electrically insulated bearing having a rolling element interposed between an outer ring and an inner ring, wherein the outer ring comprises a metal outer ring main body having a track on which the rolling element rolls, and an outer ring main body of the outer ring main body. An insulating thin film having a thickness of 0.1 to 2.0 mm and made of an alloyed material of polyamide and polyphenylene sulfide, which covers a portion to be attached to a housing, and a thin metal plate provided on the outer surface of the insulating thin film are integrally formed. An electrically insulated bearing characterized by being molded.