JPH0758098B2 - Bearings used in special environments such as high temperatures and corrosion - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing used in a special environment such as high temperature and corrosion, for example, in a molten metal treatment furnace at the time of alloy casting, a metal melting plating tank and an electrolytic plating tank. The conventional lubrication method is used to support the rotating member with good durability in a special environment where the life of the bearing cannot be extended.

TECHNICAL BACKGROUND OF THE INVENTION Prior Art For example, a rigid type polishing tank is known as an electric polishing tank in "'77 Steel Machinery and Equipment General Guide" (published on November 25, 1976 by Heavy Industries Newspaper). As shown in FIG. 2, the steel plate A is guided by the sink roll D in the electrolytic solution C in the electrolytic plating tank B and, if necessary, the support roll E, and the steel sheet A outside the electrolytic plating tank B is guided. The surface of the steel sheet is made to run repeatedly in the electrolytic solution by conducting by means of a conductor roll and a hold-down roll (not shown), and current is passed between the anode rod and the steel sheet via the conductor roll which is the cathode in the electrolytic solution. Is electroplated. The shafts at both ends of the sink roll D and the support roll E are fitted in the roll end fitting holes of the support member fixed to the upper end portion of the plating tank, but the rolls are rotated at high speed. ,
A slide bearing is interposed between the support member and the roll to prevent wear between the support member and the roll.

Here, the sink roll D and the support roll E,
The bearing that supports them is always in a corrosive environment due to the electrolytic solution because it is in the electrolytic solution.

By the way, regarding the corrosion prevention measures for those rolls D and E,
For example, various improvements have been made in the past due to the improvement of materials, but even in those cases, no particular consideration has been given to bearing corrosion prevention measures.

Problems with the Prior Art For this reason, there is a risk that the bearing may become unusable early due to corrosion. If the bearing becomes unusable due to corrosion, it is necessary to stop the operation of the electrolytic plating device and replace the bearing each time, which leads to a significant decrease in operation.

Accordingly, the inventors of the present application previously proposed a bearing in which the inner ring, the outer ring and the rolling elements are made of ceramics having heat resistance and corrosion resistance (Japanese Patent Application No. 59-64844).

Problems to be Solved by the Invention In the prior invention, particularly when the inner and outer races and the rolling elements are both ceramics, because of their high heat resistance and corrosion resistance, the life is extended compared to conventional slide bearings, Further, although the quality of the matte is improved, it has the following drawbacks.

a. Ceramics such as silicon nitride, which is the material of the bearing, is expensive and hard and difficult to process, resulting in high processing cost.
It becomes a fairly expensive bearing.

b. Since the coefficient of thermal expansion of ceramics such as silicon nitride, which is the material of the bearing, is 1/4 to 1/5 of that of metal, the bearing is placed in a molten metal plating tank electrolyte, that is, in a high temperature environment of 400 to 700 ° C. When used in, it is necessary to closely manage the fit and clearance between the inner ring and the metal shaft to which it is fitted, and the outer ring and the metal housing to which it is fitted.

The fitting of the inner ring and the shaft is particularly important.If the fitting is selected incorrectly, the inner ring will be directly connected to the shaft due to thermal expansion of the shaft if the fitting is excessive, and the inner ring will not be fitted to the shaft if the fitting is insufficient. Any of them will be damaged due to rattling in between.

c. Since the ceramic material such as silicon nitride, which is a material of the bearing, is weak against an impact load, it is damaged especially when an excessive impact load is applied, and it is difficult to endure the rattling of the fitting portion.

d. Since it is practically difficult to manufacture a cage using ceramics such as silicon nitride, which is the material of the bearing, it is unavoidable to adopt a model without a cage as a bearing that can withstand special environments such as high temperature and corrosion. This is an obstacle to the further extension of life.

Means for Solving the Problems In order to solve the problems of the preceding invention, the present invention provides a rolling element made of ceramics as a heat resistant and corrosion resistant member between an inner ring and an outer ring made of a heat resistant metal. Dress, inner ring,
Except for the radial mating surface that is fitted with the support of the outer ring,
At least the exposed surface is coated with ceramics as a heat resistant and corrosion resistant member.

Here, the radial fitting surface refers to a cylindrical surface where the inner and outer rings are fitted to the support, that is, the inner peripheral surface of the inner ring and the outer peripheral surface of the outer ring. Further, the exposed surface refers to a surface other than the fitting surface of the inner and outer races with which the support body is fitted. For example, in FIG.

This bearing is mainly applied to a full-roller type or a cylindrical roller type with a retainer, and when using it as a roller bearing with an inner ring, an outer ring and a retainer, for example, heat resistant steel is used as a heat resistant metal.

Ceramics as heat-resistant and corrosion-resistant members are silicon nitride ceramics when they are rolling elements, vanadium carbide (VC) or chrome carbide (CrC), niobium when they are coatings for inner and outer rings and cages. Carbides such as carbide (NbC) are suitable.

The ceramic coating layer on the surfaces of the inner and outer races and the cage is usually set to have a thickness of 6 μm or more.

The fitting surface of the inner and outer rings which is not covered with the ceramics is usually a fitting surface with the shaft or the housing. In addition, the inner and outer races also include a separate collar for receiving rollers that may be used in combination with a part of the inner and outer races. Further, when the axial positioning of the inner and outer races and the collar retainer on the housing and the collar retainer are in a fitting state in which the dimension cannot be adjusted in the axial direction, at least one of the end faces of the inner and outer races or the separate collar is required. One is the mating surface without the ceramic coating.

Action The rolling element made of ceramics exhibits heat resistance and corrosion resistance by itself. When used as inner / outer rings and roller bearings with a cage, the cage is made of heat-resistant metal and is a heat-resistant component that can be easily processed. The surface covered with ceramics exhibits corrosion resistance as it is. Therefore, the cage retains its entire surface for corrosion resistance. The fitting surface of the inner and outer rings with the support, which is not coated with ceramics, facilitates the grinding finish for adjusting the fitting with the support, and is isolated from the corrosive environment by the close fitting due to the proper fitting with the support. It will have corrosion resistance. As a result, the inner and outer rings also exhibit corrosion resistance on their entire surfaces.

Further, since the fitting surfaces of the inner and outer rings with the support body are not covered with ceramics, the fitting surfaces serve as a relief portion for the amount of metal expansion when the bearing is used at a high temperature.

Practical example As shown in FIG. 1, the case of a cylindrical roller bearing 3 with a retainer that rotatably holds a rotating shaft 1 used in a high temperature and corrosive environment in a holding hole 2a of a supporting member 2 is shown. Has been done.

The bearing 3 includes an inner ring 31 and an outer ring 32 made of heat-resistant steel, a cylindrical roller 34 made of ceramics held by a cage 33 made of heat-resistant steel and interposed between the inner and outer rings 31, 32, and inner and outer rings 31, 32. It is a combination with a separate heat-resistant steel roller receiving collar 35, 36 provided at one end. . The roller receiving flanges 35, 36 receive the roller 34 in the axial direction with the roller receiving flanges 31a, 32a integrally formed at one end of the inner and outer rings 31, 32, but by being separate from the inner and outer rings 31, 32, The roller 34 held by the cage 33 can be incorporated between the inner and outer rings 31 and 32 with the collar. However, assembling the rollers and holding between the inner and outer rings, various types can be adopted depending on the usage mode of the bearing, and in some cases, the type of the all roller type cylindrical roller bearing without the retainer 33 is adopted. Good.

The inner ring 31 is fitted to the stepped portion 1a on the outer circumference of the shaft 1, and is fitted to the stepped portion 1b beside the stepped portion of the shaft 1 and to the groove 1c on the stepped portion 1a so as to face the stepped portion 1b. The collar receiving ring (11) is positioned and held in the axial direction together with the roller receiving collar (35).

The outer ring 32 is fitted to the stepped portion 2b formed on the inner periphery of the holding hole 2a of the support member 2, and has a stepped portion 2c beside the stepped portion of the holding hole 2a,
It is positioned and held in the axial direction together with the roller receiving collar 36 by the fixing sleeve 21 which is opposed to the stepped portion 2c and is fitted into the stepped portion 2b and prevented from coming off.

Inner ring 31, outer ring 32 and roller collars 35, 36 forming part of them
Is the fitting surface of the shaft 1 and the support member 2, especially the inner ring 31 and the collar 35 are the inner peripheral surfaces 31b and 35a, and the outer ring 32 and the collar 36 are the outer peripheral surfaces 32b and 3
The surface except 6a, and the entire surface of the cage 33, are coated with vanadium carbide (VC) or chromium carbide (CrC) carbide, that is, ceramics 37 at a thickness of at least 6 μm or more, preferably 10 to 15 μm. (So-called TD processing).

Inner ring 31, inner peripheral surface 31b, 35a of the collar 35, outer ring 32, outer peripheral surface 3 of the collar 36
After the coating treatment on the surfaces of the inner and outer races 31, 32 and the collars 35, 36, 2b, 36a form a fitting or gap between the stepped portion 1a of the shaft 1 and the stepped portion 2a of the supporting member 2 to which they are fitted. Grinded for properness.

The inner and outer races 31 and 32 and the brims 35 and 36 are subjected to the above-mentioned coating treatment after being subjected to the polishing process.
This is because the 1,32 and the tsuba 35,36 shrink considerably, and the satisfactory fitting or clearance condition cannot be achieved by polishing before the coating treatment in which the shrinkage is expected in advance.

The size adjustment of the inner and outer rings 31, 32 and the roller 34 contracted by the coating process is dealt with by selecting the size of the roller 34 and incorporating a roller having an appropriate size.

Advantageous Effects of Invention According to the present invention, when the cage is used as the inner and outer rings and the roller bearing with the retainer, the cage is made of a heat-resistant metal and forms a heat-resistant component that is easy to process, and the coating of the ceramic is necessary together with the rolling element made of the ceramic. Since it exhibits excellent heat resistance and corrosion resistance, both material cost and processing cost are lower compared to the case where both the inner and outer rings are made of ceramics, the product price is about 1/2 or less, and in the case of the example With the adoption of a container, the bearing performance and durability can be further improved.

In addition, the inner and outer rings are not covered with ceramics on their mating surfaces, so size adjustments such as grinding can be easily performed at any time, and there is no need to closely manage the fit or gap with the support. In addition to improving yield, preventing mismanagement and premature damage due to excessive impact, the mating surfaces of the inner and outer rings are not covered by ceramics, but are properly protected from high temperature and corrosive environments by proper fitting with the support. Is
Does not impair the corrosion resistance of the bearing.

Furthermore, since the fitting surfaces of the inner and outer races with the support body are not covered with ceramics, at high temperatures such as when this bearing is used, this fitting surface serves as a relief part for the amount of metal expansion, and the metal and ceramics It is possible to prevent the ceramic layer from peeling due to the difference in thermal expansion coefficient from

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a rotating body that requires a bearing under a high temperature and corrosive environment, and FIG. 2 is a sectional view showing an embodiment of the present invention. 1 …… Rotary shaft (support) 2 …… Support member (support) 31 …… Inner ring (3 …… bearing) 32 …… Outer ring (3 …… bearing) 33 …… Cage (3 …… bearing) 34 …… Cylindrical roller (3 …… Bearing) 35,36 …… Roller receiving collar (3 …… Bearing) 31b, 35a …… Inner circumference (fitting surface) 32b, 36a …… Outer circumference (fitting surface) 37 …… Coating

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliographic references Sho 53-101954 (JP, U) JP 53-47860 (JP, B2) JP 53-47861 (JP, B2)

Claims (9)

[Claims] 1. A rolling element made of ceramics as a heat-resistant and corrosion-resistant member is interposed between an inner ring and an outer ring made of a heat-resistant metal, and a radial fitting surface fitted to a support for the inner ring and the outer ring is provided. Except for the above, at least the exposed surface is covered with ceramics as a heat-resistant and corrosion-resistant member, which is used in special environments such as high temperature and corrosion 2. The high temperature roller bearing according to claim 1, wherein the bearing is a full-roller type roller bearing consisting of inner and outer races and rolling elements.
Bearings used in special environments such as corrosion 3. A roller bearing comprising an inner and outer race, a rolling element, and a cage made of a heat-resistant metal whose surface is coated with ceramics as a heat-resistant and corrosion-resistant material. Bearings to be used in the special environment such as high temperature and corrosion 4. The bearing used in a special environment such as high temperature and corrosion according to any one of claims 1 to 3, wherein each of the inner ring and the outer ring is made of heat resistant steel. 5. A bearing for use in a special environment such as high temperature and corrosion according to claim 3, wherein the cage is made of heat resistant steel. 6. A bearing for use in a special environment such as high temperature and corrosion according to any one of claims 1 to 4, wherein the rolling element is made of silicon nitride ceramics. 7. The high temperature according to any one of claims 1 to 5, wherein the cage, the inner ring and the outer ring are coated with a ceramic such as vanadium carbide or chromium carbide. Bearings used in special environments such as corrosion 8. The ceramic coating layers of the cage, the inner ring and the outer ring have a thickness of 6 μm or more.
Bearings used in special environments such as high temperature and corrosion described in paragraph 9. The fitting surface of the inner ring and the outer ring is a ground finish surface after coating with ceramics.
Bearings used in special environments such as high temperature and corrosion described in paragraph