JPH0134976Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to bearings used in special environments such as high temperatures and corrosion, for example, in molten metal processing furnaces during alloy casting,
It is used to support rotating members with good durability in special environments where conventional lubrication methods cannot extend bearing life, such as in the liquid of metal fusion plating baths and electrolytic plating baths.

Technical background of the invention A. Prior art For example, a vertical plating tank as an electroplating tank is known from the ``'77 Steelmaking Machinery and Equipment Overview'' (published by Juuko Shimbun on November 25, 1977). This is the third
As shown in the figure, a steel sheet A is guided by a sink roll D in an electrolyte C of an electrolytic plating tank B, and further by a support roll E as necessary, and is guided by a conductor roll (not shown) outside the electrolytic plating tank B. Guided by hold-down rolls, the steel plate is repeatedly moved through an electrolytic solution, and the surface of the steel plate is electrolytically plated by passing current between the anode rod and the steel plate via the cathode conductor roll in the electrolytic solution. . The shafts at both ends of the sink roll D and support roll E are fitted into the roll end fitting holes of the support member fixed to the upper end of the plating tank, but since these rolls are rotated at high speed, A sliding 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, the support roll E, and the bearings that support them are in an electrolytic solution, so they are always in a corrosive environment due to the electrolytic solution.

By the way, various measures have been taken to prevent corrosion of the rolls D and E, for example, by improving the materials, but even in those cases, no particular consideration was given to measures to prevent corrosion of the bearings.

(b) Problems with the prior art As a result, there was a risk that the bearing would become unusable due to corrosion. If a bearing becomes unusable due to corrosion, the operation of the electrolytic plating equipment must be stopped and the bearing replaced each time, leading to a significant drop in operation.

C. Prior invention Therefore, the inventors of the present application first developed a fully roller type bearing as shown in FIGS. 4 and 5, in which the inner ring, outer ring, and rolling elements are made of heat-resistant and corrosion-resistant ceramics. proposed (patent application 1986-64844)
issue).

Problems to be solved by the invention In the previous invention, when both the inner and outer rings and the rolling elements were made of ceramics, the high heat resistance,
Due to its corrosion resistance, it has a longer service life and improved plating quality compared to conventional plain bearings, but it is practically difficult to manufacture cages using ceramics such as silicon nitride, which is used as the material for bearings. Therefore, in order to withstand special environments such as high temperatures and corrosion, a full roller type without a cage must be adopted. For this reason, the cylindrical rollers come into contact with each other inside the bearing during rotation, causing severe vibration and wear, which may lead to early damage.

b. In the all-roller type, the number of rollers is more than necessary considering the load capacity, and as a result of incorporating a large number of rollers, the bearing becomes expensive, especially in the case of ceramic bearings that use expensive materials.

Means for Solving the Problems In order to solve the problems of the previous invention, this invention includes rolling elements made of ceramics as heat-resistant and corrosion-resistant members, which are held in a heat-resistant metal cage;
The surface of the cage is coated with ceramic as a heat-resistant and corrosion-resistant member.

This bearing is mainly applied to a cylindrical roller type, for example, heat-resistant steel is used as the heat-resistant metal forming the cage, and the cage is of an inner ring guide type or the like.

For example, silicon nitride ceramics is suitable as a heat-resistant and corrosion-resistant member for bearings, and is applied to rolling elements and inner and outer rings. Suitable ceramics for coating the cage are carbides such as vanadium carbide (VC), chromium carbide (CrC), and niobium carbide (NbC).

The ceramic coating layer of the cage is usually set to a thickness of 6 μm or more.

Note that the ceramic bearing may be one in which the inner and outer rings are made of heat-resistant metal like the cage and covered with ceramics.

Function Ceramic bearings exhibit heat resistance and corrosion resistance due to the ceramics in the inner and outer rings and rolling elements themselves. The cage is a heat-resistant part made of heat-resistant metal and easily machined, and the ceramic-coated surface exhibits corrosion resistance as it is and holds the rolling elements at the required pitch.

Embodiment As seen in the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 2, the ceramic rolling elements 1 of a ceramic bearing are held by an inner ring guide type cage 2. The case is shown.

Both the inner ring 3 and the outer ring 4 are made of ceramics, like the rolling elements 1, and silicon nitride ceramics is used as the ceramic material. The cage 2 is
Made of heat-resistant steel such as SKH material, the surface is coated with vanadium carbide (VC), niobium carbide (NbC),
A carbide called chromium carbide (CrC), ie, ceramics 21, is coated (so-called TD treatment) to a thickness of at least 6 μm or more, preferably 10 to 15 μm.

Due to the adoption of the inner ring guide type retainer 2, the inner ring 3 of both the first and second embodiments has integral flanges 31 at both ends, whereas the outer ring 4 of the first embodiment of FIG. In this case, one end has an integral tsuba 41 and the other end has a separate tsuba 42.
In the case of the second embodiment in FIG. 2, it is a straight type.

On the other hand, since the cage 2 made of heat-resistant steel shrinks and changes in size due to the TD process in which the ceramic 21 is coated, the cage 2 is manufactured in anticipation of the shrinkage and is coated with the coating process.

When the bearing is used in a high-temperature environment of 400 to 700°C, the heat-resistant steel cage 2 exhibits a coefficient of thermal expansion that is about four times that of the ceramic inner and outer rings 3 and 4.
Since it is an inner ring guide type, there is no particular problem as long as the gap between the inner ring 3 and the inner ring 3 is widened to bring it a little closer to the outer ring 4.

Even when the bearings of the first and second embodiments were applied to a bearing for a support roll in a hot-dip galvanizing tank, which is used in a high temperature and corrosive environment, there was no problem in using the cage 2.

Effects According to this invention, the cage is a heat-resistant part made of heat-resistant metal and is easy to process, and the ceramic coating provides the necessary heat resistance and corrosion resistance together with the ceramic rolling elements and inner and outer rings. Because I will demonstrate
Ceramic rolling elements in ceramic bearings used in special environments such as high temperatures and corrosion can be supported without problems in terms of heat and corrosion resistance. Improves bearing life compared to full roller type.

In addition, by using a cage, it is possible to assemble the bearing by holding the number of rolling elements at the desired pitch that meets the load capacity and other requirements without using a full-roller type, which reduces the number of expensive ceramic rolling elements. The lower the bearing price, the lighter the bearing will be.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view of the first embodiment of this invention, FIG. 2 is a half-sectional view of the second embodiment, and FIG. 3 is a high-temperature,
A cross-sectional view showing an example of a rotating body that requires a bearing in a corrosive environment, and FIGS. 4 and 5 are cross-sectional views showing examples of prior art ceramic bearings. ,...Ceramics bearing, 1...Rolling element,
2... Cage, 21... Ceramics, 3... Inner ring, 4... Outer ring.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A rolling element made of ceramics as a heat-resistant and corrosion-resistant member is held in a heat-resistant metal cage, and the cage has a heat-resistant and corrosion-resistant surface. It is covered with ceramics as a component. Ceramic bearings used in special environments such as high temperatures and corrosion. (2) A ceramic bearing for use in special environments such as high temperatures and corrosion, as set forth in claim 1 of the utility model registration, wherein the rolling elements are cylindrical rollers. (3) A ceramic bearing for use in special environments such as high temperatures and corrosion as described in Claim 1 of the Utility Model Registration Claim, in which the retainer is of an inner ring guide type. (4) A ceramic bearing for use in special environments such as high temperatures and corrosion, as set forth in claim 1 of the utility model registration, in which the cage is made of heat-resistant steel. (5) The coated ceramic is a carbide such as vanadium carbide, niobium carbide, chromium carbide, etc. Used in special environments such as high temperatures and corrosion as described in any of claims 1 to 4 of the utility model registration claim. Ceramic bearings. (6) A ceramic bearing for use in special environments such as high temperatures and corrosion, as set forth in claim 5 of the utility model registration, in which the ceramic coating layer has a thickness of 6 μm or more.