JPH09209114A - Bearing for roll in hot-dip metal plating bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing for a roll in which maintenance is easy at the time of reusing in such a manner that wear resistance in a hot-dip metal plating bath is excellent, stable use is possible over a long period, and furthermore, the removal of plating metal is easy by pickling at a cost more inexpensive than that for the conventional one.

SOLUTION: In a bearing used in a hot-dip metal plating bath, on the sliding face of a sleeve 7 as the member on the rotating side, in contact with the sleeve, three layers of sprayed coatings composed of a primary layer 8 of a Co base alloy, a secondary layer 9 of a Co base cermet and a third layer 10 of Mo base cermet are formed, and the thickness of the primary layer and secondary layer is regulated to 0.05 to 0.70mm, and the thickness of the third layer is regulated to 0.03 to 0.35mm.

COPYRIGHT: (C)1997,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller bearing used in a plating bath in a continuous hot metal plating facility.

[0002]

2. Description of the Related Art Rolls such as sink rolls, which are conventionally immersed in a plating bath of a continuous hot-dip galvanizing facility, are under severe conditions in which they come into contact with high-temperature hot metal. Conventionally, corrosion resistant and heat resistant stainless steel has been used for the side members.

However, the wear resistance is poor, the alloy reaction with the molten metal is strong, and the alloy layer with the molten metal grows, which causes rotation failure. For reuse, polish again,
In some cases, repairs such as padding were necessary.

Welding is the mainstream as a means for mounting the sleeve on the roll main body, but since it takes a lot of time to attach and detach the sleeve, the life of the sleeve is short, and the labor required for these is increased.

As means for extending the life of these bearings, a method of welding WC-12Co or the like, and a sliding member between the bearing and the shaft are made of a solid lubricating member as a fixed member and a ceramic member as a rotating member. Method (JP-A-5-2224)
No. 99), a method of depositing a Co-based alloy consisting of two layers, upper and lower, on the surface of the shaft of a roll (Actual No. 5-69155).

A method of partially fitting a superhard metal tip such as cobalt-containing tungsten carbide for the purpose of improving only the life of the bearing metal (Japanese Patent Laid-Open No. 5-126).
No. 135), the stationary side member is made of ceramics, and the rotating side member is made of cermet having a hardness lower than that of the ceramics to improve the wear resistance of the stationary side member (JP-A-5-4400).
2), a method of mounting a ring-shaped ceramic sintered body on the surface of a metal bearing shell (Japanese Patent Laid-Open No. 1-316443),
A method of manufacturing the sliding portion of the bearing with a special carbon material in which pores are filled with silicon carbide (JP-A-3-126854)
Etc. have been proposed.

[0007]

However, in the build-up of the Co-based alloy, rotation failure occurs due to the formation of an alloy layer with the molten metal, and in the spraying of WC-12Co, the plating metal cannot be removed by pickling. It takes a lot of time to care for it. Further, if it is made of ceramics, it is likely to be peeled off or damaged due to thermal stress, and the manufacturing cost will increase. Further, in the method of increasing the hardness of the metal part only for the purpose of improving the life of the bearing metal, there are problems such as severe wear of the sleeve, causing rotation failure, frequent replacement of the sleeve, and increase in manufacturing cost of the metal itself. Was.

Therefore, the object of the present invention is not only excellent in wear resistance in a molten metal plating bath and stable in use for a long period of time, but also easy to clean after reuse because the plating metal can be easily removed by pickling. Therefore, it is to provide a roll bearing whose cost is lower than the conventional one.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted research to achieve the above-mentioned object, placed basic performance of a bearing on cost and ease of maintenance at the time of reuse, and performed various surface treatment methods and materials. By considering the combination, first, it was considered which one of the bearing portion of the stationary member and the sleeve of the rotating member should have a longer life in terms of cost. Considering to extend the life of both, it is possible to increase the hardness of both, but it has been confirmed that the wear of both increases as the hardness of both increases, and the hardness of one is lower than that of the other. It is known that the life is increased in some cases.

Therefore, as to which of the two should be increased in hardness, the hardness of the sleeve is increased in cost as a result of studying the reproducibility by attaching and detaching the sleeve to the roll, assembling the roll bearing into the roll hanger, and the like. It is preferable to extend the life. For that purpose, in order to prevent peeling of the thermal spray coating or deformation of the base material due to the entrapment of foreign matter due to the influence of thermal stress and hardness difference during use, the thermal spray layer to be sprayed has As shown in Table 2, a lower layer coating and an intermediate coating near the sleeve are provided to provide a hardness gradient, and the upper layer is sprayed with Mo cermet or the like having excellent sliding characteristics and wear characteristics as shown in Table 2. With a three-layer structure,
The inventors have found that the above-mentioned problems can be solved, and have reached the present invention.

[0011]

[Table 1]

[0012]

[Table 2]

◯: Good Δ: Slightly inferior ×: Significant corrosion is visible and unsuitable. That is, the first aspect of the present invention is a roller bearing used in a molten metal plating bath, in which a sleeve, which is a rotating side member, slides. On the moving surface, a Co-based alloy as the first layer, a Co-based cermet as the second layer, and M as the third layer in contact with the sleeve.
A bearing for rolls in a molten metal plating bath, characterized by having a sprayed coating consisting of three layers of o-based cermet;
The thickness of the first layer and the second layer of the coating is 0.05-0.
The bearing according to the first aspect has a thickness of 70 mm and a thickness of the third layer of 0.03 to 0.35 mm.

[0014]

In the present invention, the sliding surface of the sleeve, which is the rotating member, is provided with a three-layer thermal spray coating. That is, the first layer of cobalt-based alloy is formed on the sleeve base material, and Co is formed on the first layer.
The second layer of the base cermet and the third uppermost layer of the Mo base cermet are sequentially formed, and the role of each layer is as follows.

The first layer is to secure adhesion and toughness with the base material, and the second layer is a bonding layer of the first layer and the third layer in consideration of the coefficient of linear expansion and hardness gradient. The third layer is sliding wear resistant,
It is the top layer of the film that has seizure resistance and corrosion resistance.

The thickness of the first layer and the second layer is 0.0
If the thickness is less than 5 mm, the effective hardness gradient and the deformation of the base material cannot be prevented, and if the thickness exceeds 0.70 mm, the risk of peeling increases due to internal stress. On the other hand, if the thickness of the third layer is less than 0.03 mm, the penetration of molten metal is insufficient, and if it exceeds 0.35 mm, peeling occurs as in the case of the first and second layers. Since there is a risk of, it was set to 0.03 to 0.35 mm.

[0017]

1 is a sectional view showing the structure of a sprayed coating applied to a sliding surface of a sleeve which is a rotating side member of a bearing of the present invention, and FIG. 2 is a plating tank side of a continuous galvanizing apparatus according to the present invention. It is explanatory drawing which shows a cross section, and is demonstrated below, referring to these.

As shown in FIG. 2, the hot-dip galvanizing bath 1 includes a sink roll 2 and one or two support rolls 3.
The heat-annealed steel sheet 6 to be plated enters the hot-dip galvanizing bath 1 from the snout 4 and the sink roll 2
The direction is changed upward by the support roll 3, the warp of the plate in the width direction is corrected by the support roll 3, and the high-speed gas is blown by the wiping nozzles 5 arranged on both sides of the steel plate above the plating bath. The amount of plating adhered is adjusted to a predetermined amount by adjusting. The arrow in the figure indicates the sheet passing direction.

In the continuous hot dip galvanizing equipment described with reference to FIG. 2, the surface treatment of the material shown in Table 3 was applied to the bearing sleeve for the roll bearing in the zinc bath, and the test was performed. In addition,
The actual machine operating conditions at this time are line speed 60-130mpm,
It was a zinc bath having a line of tension up to MAX 4 ^T and a bath temperature of 460 ° C. and a bath composition of 0.15% Al—Zn.

The sleeve evaluation method after use is as follows: (1) When the step due to abrasion reaches 0.5 mm or more after cleaning with pickling (after pickling with sulfuric acid) (up to 50% of the sprayed film thickness in the case of spraying). (2) When the thermal spray peeling area reaches 20% or more of the used area, the life is judged by setting the inspection criteria of two items such as wear amount and appearance, as shown in, until the inspection criteria are reached. Displayed as the number of days used.

[0021]

[Table 3]

◯: Good Δ: Severe wear on either side ×: Not usable due to large deformation of the base material due to wear. From the results of the actual machine test in Table 3, Mo cermet / C with a two-layer structure is shown.
o As with the three-layered Mo cermet / Co cermet / Co-based alloy, the cermet was used for 7 days, which was 35 days with 5 pickling cycles after use. However, the Mo cermet having Co cermet as the first sprayed layer was used. As shown in Table 1 above, the thermal sprayed coating according to the present invention in which the Co cermet is the second layer is more appropriately considered than the / Co cermet, because the thermal expansion coefficient and the gradient of hardness are properly considered. This is advantageous from the viewpoint of preventing the effect of hardness difference.

3 formed on the sleeve in this embodiment
A cross-sectional view of the thermal spray coating composed of layers is shown in FIG. Sleeve 7
The thickness of the first layer 8 of the Co-based alloy and the second layer 9 of the Co-based cermet applied in contact with was 0.4 mm, and the thickness of the third layer 10 of the Mo-based cermet was 0.2 mm.

[0024]

As described above, in the roll bearing provided with the thermal spray coating of the present invention, the thermal spray coating applied on the sleeve is the Co-based alloy layer as the lower layer, the Co-based cermet layer as the intermediate layer, and the uppermost layer. The (third layer) is a film composed of three layers of Mo-based cermet, and has a gradient in which the linear expansion coefficient of each of the base material sleeves, which are austenitic stainless steels, changes gradually. With an appropriate gradient from the hardness Hv200 of the base material to the hardness Hv1100 of the third layer, it has excellent wear resistance in the plating bath, is less affected by thermal stress and hardness differences, and is easy to maintain when reusing. Therefore, it is possible to provide a roll bearing that is less expensive than the related art. In addition, rotation defects during use are reduced,
Manufacturing is stable.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of a thermal spray coating applied to a sliding surface of a rotating member in a bearing of the present invention.

FIG. 2 is an explanatory view showing a side cross section of a plating tank of the continuous hot-dip galvanizing apparatus according to the present invention.

[Explanation of symbols]

 1 Hot-dip bath 2 Sink roll 3 Support roll 4 Snout 5 Wiping nozzle 6 Steel plate 7 Sleeve 8 First layer 9 Second layer 10 Third layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Kato 2-17-4 Kotogawa, Saitama Prefecture

Claims (2)

[Claims] 1. A roll bearing used in a molten metal plating bath, comprising a Co-based alloy as a first layer in contact with the sleeve, which is a rotating side member, and a second layer on a sliding surface of the sleeve.
A bearing for a roll in a molten metal plating bath, which has a sprayed coating consisting of three layers of Co-based cermet as a layer and Mo-based cermet as a third layer. 2. The first and second layers of the coating have a thickness of 0.05 to 0.70 mm, and the third layer has a thickness of 0.03 to 0.
The bearing according to claim 1, which is 35 mm.