JP2000319770A - Roll bearing for galvanizing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll bearing for galvanizing, with which it is surely prevented to invade molten zinc into a gap between a bearing part and a bearing box for supporting this bearing part, in the state of dipping the roll bearing for galvanizing into a galvanizing bath. SOLUTION: The roll bearing for galvanizing, supporting a support roll, is constituted of a sliding bearing with the cylindrical bearing box 12 and a cylindrical sleeve 13 disposed in the inner peripheral surface of the bearing box 12 and served as the bearing part for inserting the shaft end part of the support roll. When this support roll is dipped into the galvanizing bath and when setting a gap between the inner peripheral surface of the bearing box 12 and the outer peripheral surface of the cylindrical sleeve is (d) and dipped depth of the support roll is H, by setting this gap (d) to not more than a limit gap (dMAX) obtd. by basing on 240/H, the invasion of molten zinc into the gap (d) is inhibited by utilizing the surface tension of the molten zinc. As a result, it is prevented to act an excessive compression force on the bearing part in the cooling process when the roll bearing is pulled up from the galvanizing bath at the check and maintenance time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll bearing for hot dip galvanizing, which rotatably supports a support roll for guiding a strip immersed in the hot dip galvanizing bath in the hot dip galvanizing bath.

[0002]

2. Description of the Related Art As a conventional hot-dip galvanized roll bearing, for example, the one described in Japanese Patent Application Laid-Open No. 4-124254 (or Japanese Patent Application Laid-Open No. 5-44002) is known. In these conventional examples, a fixed-side member in a roll bearing used by being immersed in a molten metal plating bath is made of cermet (or ceramics), and a rotating-side member is made of stainless steel (or cermet). It is disclosed that a roll bearing for molten metal plating having a small amount of wear and a small coefficient of friction can be provided.

[0003]

However, in the above conventional example, the fixed side member of the roll bearing for molten metal plating is made of ceramic or cermet.
While improving the wear resistance, the coefficient of friction can be reduced, and smooth rotation of the roll can be ensured, but the fixed side member is formed in a semi-cylindrical shape. It is necessary to fix and hold the support frame so that it does not move in the circumferential direction, and it is installed in the storage recess formed on the inner peripheral surface of the insertion hole formed in the support frame, so it is used for molten metal plating. When the roll bearing is immersed in the support frame and the molten metal bath, the molten metal bath temperature is as high as 400 ° C. or higher, and the thermal expansion coefficient of the support frame is larger than that of ceramic or cermet. A gap is formed between the ceramic and the insertion hole of the support frame inside, and molten metal enters into this gap. In this state, the molten metal mesh together with the support frame is used for inspection and maintenance. When the roll bearing is taken out of the molten metal bath, the molten metal that has entered the gap between the ceramic and the insertion hole of the support frame is solidified, and the amount of shrinkage of the support frame relative to the ceramic is large. There is an unsolved problem that a large load is applied and cracks occur.

[0004] In particular, when a ceramic as a stationary member is formed as a cylindrical sleeve, a large compressive force acts on the entire peripheral surface of the cylindrical sleeve, so that the frequency of cracks is increased and the amount of wear is increased. However, even if the number is small, it is necessary to replace the cylindrical sleeve, and there is an unsolved problem that the cost increases. Therefore, the present invention has been made by focusing on the unsolved problems of the above-described conventional example, and a state in which a roll bearing for hot-dip galvanizing is immersed in a hot-dip galvanizing bath using the surface tension of hot-dip zinc. SUMMARY OF THE INVENTION It is an object of the present invention to provide a hot-dip galvanized roll bearing capable of reliably preventing molten zinc from entering a gap between a bearing portion and a bearing box supporting the bearing portion.

[0005]

According to a first aspect of the present invention, there is provided a hot-dip galvanizing roll bearing comprising a support roll which is immersed in a hot-dip galvanizing bath to guide a strip. A hot-dip galvanizing roll bearing rotatably supported in a bath, comprising: a bearing housing; a bearing for supporting a shaft end of the support roll disposed in the bearing housing; and a sliding bearing. When the gap between the box and the bearing is immersed in a hot-dip galvanizing bath, the gap is set to be equal to or less than a limit gap that can prevent the penetration of the molten zinc into the gap due to the surface tension of the molten zinc. And

In the invention according to the first aspect, the gap d between the bearing housing and the bearing portion supporting the support roll is equal to or smaller than the limit gap in a state where the hot-dip galvanizing roll bearing is immersed in the hot-dip galvanizing bath. With this setting, it is possible to reliably prevent molten zinc from entering the gap between the bearing box and the bearing portion due to the surface tension of the molten zinc.

Further, the roll bearing for hot-dip galvanizing according to the second aspect is the invention according to the first aspect, wherein the limit gap d _MAX is such that the immersion depth of the support roll from the bath surface is H. It is characterized in that d _MAX = 240 / H is selected. In the invention according to the second aspect, since the limit gap d is selected based on the immersion depth H of the support roll from the bath surface, it is necessary to select an optimum limit gap according to the immersion depth of the support roll. Can be.

[0008] As the critical gap d, the more reliably prevented the infiltration of molten zinc, it is preferable to select the d _{MA X} = 150 / H.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a hot-dip galvanizing apparatus to which the present invention can be applied. In the drawing, reference numeral 1 denotes a hot-dip galvanizing bath filled with hot-dip zinc at 465 ° C., for example. A steel plate 2 carried out of a continuous annealing furnace is immersed in a hot-dip galvanizing bath 1 through a snout 3, , Is guided upward by a pair of support rolls 5 and is lifted upward. The amount of plating applied is controlled by a wiping nozzle 6, then guided by a support roll 7 on a bath, and conveyed to another process.

Here, as shown in FIGS. 2 and 3, the support roll 5 includes an inclined arm portion 10a immersed in the hot-dip galvanizing bath 1 and a horizontal support portion 10 formed at the tip thereof.
and b. It is rotatably supported by a hot-dip galvanizing roll bearing 11 disposed on a pair of front and rear roll support arms 10 composed of b. The roll bearing 11 includes a bearing box 12 composed of a cylindrical portion 12a and a flange portion 12c having an insertion hole 12b provided at the left and right open ends thereof;
The bearing housing 12 includes a cylindrical sleeve 13 made of ceramic as a bearing disposed in the cylindrical portion 12a.

The bearing housing 12 has a cylindrical portion 12a and one flange portion 12c formed integrally with each other. In this state, a cylindrical sleeve 13 is inserted and held in the cylindrical portion 12a, and then the other flange portion is formed. The outer peripheral surface of the cylindrical portion 12a is manufactured by fixing the portion 12c by welding, for example, by welding, and the outer peripheral surface of the cylindrical portion 12a is inserted into the cylindrical sleeve 13 while the inclined arm portion 1 of the roll supporting arm 10 is in contact therewith.
0a and the connecting point of the horizontal support portion 10b, and this state flange portion 12c is welded to the inclined arm portion 10a and the horizontal support portion 10b of the roll support arm 10, and the cylindrical portion 12
The support member 14 is supported by the roll support arm 10 by welding a reinforcing support piece 14 to an upper end portion of the outer peripheral surface of the support member 14.

When the gap d between the inner peripheral surface of the cylindrical portion 12a of the roll bearing 11 and the outer peripheral surface of the cylindrical sleeve 13 is immersed in the hot-dip galvanizing bath 1, the gap d is formed by the surface tension of the molten zinc. Is set to be equal to or smaller than the limit gap d _MAX at which the infiltration of the molten zinc into the metal is prevented. That is,
The limit gap d _MAX is calculated based on the contact angle between the molten zinc and the roll bearing, the molten zinc density, and the like, as shown in FIG.
Assuming that the immersion depth of the support roll 5 from the bath surface is H, d _MAX = represented by a curve L1 shown by a chain line in FIG.
240 / selected from H, this limit gap d _{MA X} the gap d between the outer peripheral surface of the inner peripheral surface of the cylindrical portion 12a when immersed roll bearing 11 in the molten zinc plating bath 1 and a cylindrical sleeve 13
By setting the roller bearing 11 in the hatched area below, it is possible to prevent the molten zinc from entering the gap d due to the surface tension of the molten zinc while the roll bearing 11 is immersed in the hot-dip galvanizing bath 1. If the limit gap d _MAX is selected in other regions, molten zinc infiltrates between the gaps d, and the same problem as in the conventional example occurs.

[0013] To more reliably prevent infiltration of molten zinc
Is the limit gap d_MAXIs represented by a curve L2 indicated by a solid line in FIG.
D_MAX= 150 / H and melt the roll bearing 11
Of the cylindrical portion 12a when immersed in the galvanizing bath 1
The gap d between the peripheral surface and the outer peripheral surface of the cylindrical sleeve 13 is set to this limit.
Field gap d_MAXIt is preferable to set the following. like this
In the above embodiment, the roll bearing 11 is
While immersed in the lead plating bath 1, the cylindrical portion 12a
The gap d between the inner peripheral surface and the outer peripheral surface of the cylindrical sleeve 13 is
Limit gap d_MAXThis role is set as below
The support roll 5 is rotatably supported by the bearing 11.
In this state, the cylindrical sleeve 13 moves along with the support roll 5.
Even in the rotating state, the inner peripheral surface of the cylindrical portion 12a
In the gap d between the outer peripheral surface of the cylindrical sleeve 13 and the molten zinc,
Intrusion can be prevented, so inspection and maintenance
To perform the operation, raise the roll support arm 10 and
The bearing 11 from the hot-dip galvanizing bath 1
As a result, the roll bearing 11 is cooled and the bearing housing 12
Is larger than the thermal expansion coefficient of the cylindrical sleeve 13.
The inner peripheral surface of the cylindrical portion 12a and the cylindrical three
Even when the gap d with the outer peripheral surface of the
Since no molten zinc has penetrated between them, a cylindrical three
Reliably prevents large compression force from acting on the valve 13
Can damage ceramic cylindrical sleeve
This can be reliably prevented. (Example) The immersion depth of the roll bearing 11 from the bath surface was set to 50.
0 mm, the limit gap d_MAXTo d _MAX= Based on 150 / H
Is calculated by the following formula._MAXIs 0.3m
m. Therefore, the inner peripheral surface of the cylindrical portion 12a is
Set the gap d with the outer peripheral surface of the leave 13 to 0.3 mm or less
To prevent the penetration of the molten zinc into the gap d
be able to.

Here, the bath temperature of the hot dip galvanizing bath 1 is set to 4
65 ° C, outer diameter of cylindrical sleeve 100mm, ceramic
Thermal expansion coefficient of 3 × 10^-6/ ° C, the above limit gap
Interval d _MAX= 0.3 ° 465 ° C. × (x−3) × 10^-6/ ° C × 100 mm ≦ 0.
The bearing housing 12 having a thermal expansion coefficient of x is determined so as to be 3 mm.
I just need.

That is, the bearing housing 12 may be made of a material having a coefficient of thermal expansion of x <9.5. Here, when there is no material that satisfies the above conditions, that is, for example, to manufacture a bearing box using steel having a coefficient of thermal expansion x = 12, the gap between the bearing box 12 and the cylindrical sleeve 13 in the bath is required. Since d is 0.42 mm, the limit gap d _MAX =
The difference of 0.12 mm from 0.3 mm can be covered by shrink-fitting the bearing housing 12 and the cylindrical sleeve 13.

In the above embodiment, the case where the cylindrical sleeve 13 is made of ceramics has been described. However, the present invention is not limited to this case. It may be made of a material having a small coefficient. Further, in the above embodiment, the case where the bearing portion is configured by the cylindrical sleeve 13 has been described, but the present invention is not limited to this.
The support roll 5 is formed in a semi-cylindrical shape as in the conventional example.
The bearing portion may be formed only at a portion to which a load when supporting the bearing is applied.

[0017]

As described above, according to the first aspect of the present invention, the bearing for supporting the bearing box and the support roll in a state where the hot-dip galvanized roll bearing is immersed in the hot-dip galvanizing bath. Is set to be equal to or smaller than the limit gap, it is possible to reliably prevent molten zinc from entering the gap between the bearing box and the bearing portion due to the surface tension of the molten zinc. When the hot-dip galvanized roll bearing is cooled when the hot-dip galvanized roll bearing is pulled out of the hot-dip galvanizing bath during maintenance,
Even if the bearing housing shrinks, no molten zinc remains between the bearing housing and the bearing, so that no excessive compressive force acts on the bearing and the bearing is reliably prevented from being damaged. Therefore, the effect that the life can be improved can be obtained.

According to the second aspect of the present invention, since the limit gap d is selected based on the immersion depth H of the support roll from the bath surface, the optimum limit according to the immersion depth of the support roll is determined. The clearance can be selected, and the effect of increasing the degree of freedom in selecting the material of the bearing box in relation to the immersion depth of the support roll can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a hot-dip galvanizing bath to which the present invention can be applied.

FIG. 2 is a side view showing a roll bearing for galvanizing.

FIG. 3 is an enlarged sectional view showing a roll bearing for galvanizing.

FIG. 4 is a characteristic diagram showing a relationship between a limit gap and a roll immersion depth.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot-dip galvanizing bath 2 Steel strip 3 Snout 4 Sink roll 5 Support roll 6 Wiping nozzle 11 Roll bearing for hot-dip galvanizing 12 Bearing box 13 Cylindrical sleeve (bearing part)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J103 AA02 CA25 DA01 FA09 FA15 FA26 FA30 GA02 GA15 GA52 4K027 AA02 AA22 AB42 AD17

Claims (2)

[Claims] 1. A hot-dip galvanizing roll bearing for rotatably supporting a support roll, which is immersed in a hot-dip galvanizing bath and guides a strip, in the hot-dip galvanizing bath. The support roll is provided with a bearing for supporting the shaft end and a sliding bearing.When the gap between the bearing box and the bearing is immersed in a hot-dip galvanizing bath, the surface of the molten zinc is A roll bearing for hot dip galvanizing, wherein the roll gap is set to be equal to or less than a limit gap capable of preventing infiltration of molten zinc into the gap by tension. 2. The limit gap d _MAX is defined as d _MAX = 2, where H is the immersion depth of the support roll from the bath surface.
The hot-dip galvanized roll bearing according to claim 1, wherein the roller bearing is selected to be 40 / H.