JPH06207256A - Bearing device of roll in molten metal bath and temperature control method therefor - Google Patents

Abstract

PURPOSE:To avert the direct contact of bearings and a shaft and to prevent the wear of the bearings. CONSTITUTION:The bearing device 20 of rolls 2, 3 in a molten metal bath 5 is provided with coolers 30 in plain bearing parts 21 and/or roll shaft 22 of the bearing device 20 for the rolls 2, 3 to be used by being immersed into the molten metal bath. The plain bearing parts 21 are provided with grooves. Further, the coolers 30 are provided with temp. measuring gages to exactly control the temps. of the plain bearing parts 21 and/or the roll shaft 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plain bearing device used to support a roll used by being immersed in a molten metal bath, and a temperature control method thereof.

[0002]

2. Description of the Related Art When forming a plating layer of another metal on the surface of a steel strip, in addition to plating by an electrochemical treatment, treatment by a so-called hot dipping bath in which a metal is dipped in a plating bath is widely used. ing. For example, when galvanizing the surface of a steel strip with such a hot dip bath, there is an apparatus disclosed in Japanese Utility Model Laid-Open No. 61-90852.

In this apparatus, as shown in FIGS. 7 and 8, the steel strip 1 introduced into the plating tank 4 changes its direction by a sink roll 3 and goes out of the plating tank 4 via a support roll 2.
A sink roll 3 and a support roll 2 for guiding the steel strip 1 while being immersed in a high-temperature molten metal (zinc) bath 5.
Are rotatably supported at the tip of the support arm 6 via rolling bearings 7, for example, as shown in FIG. Since the rolling bearing 7 is required to have heat resistance and abrasion resistance, it is preferably made of ceramic. In FIG. 5, the steel strip 1 guided from the continuous furnace 10 enters the hot-dip galvanizing bath 5 through the snout 8, is turned upward by the sink roll 3, corrects the warp by the support roll 2, and passes the strip. Stabilize, come out on the bath surface, nozzle 9
Is controlled to a predetermined amount of plating.

On the other hand, the slide bearing for supporting the sink roll 3 or the support roll 2 is conventionally formed of heat resistant steel. However, these plain bearings have a temperature of 450-500 ° C.
Damage is severe because it is constantly immersed in a metal bath that is melting under high temperature. In particular, when the amount of wear of the bearing becomes large, the rotation of the roll becomes poor, the steel strip passing through this roll flaps, and the amount of zinc adhered becomes uneven. For this reason, the bearings must be replaced in a short time, and there are problems that the production amount is reduced due to the stop of the line and the repair cost is high.

In order to prevent this wear, for example, in Japanese Unexamined Patent Publication No. 3-115552, a liquid jet hole is formed inside the bath of the hot dip galvanizing device, facing the roll shaft, and jetted from the liquid jet hole. A method of supporting a roll with a liquid that has been proposed has been proposed. However, in this method, since the liquid must be jetted at all times, it is expensive, and if the jet holes are clogged, a failure is likely to occur.

Further, Japanese Patent Application Laid-Open No. 3-126854 proposes a method in which a carbon material is used for a sliding portion of a bearing with a roll shaft and a groove is provided in the sliding portion. This gutter is provided to remove carbon abrasion powder and sludge in the bath that have entered the gap between the shaft and the bearing. However, even this method does not sufficiently prevent abrasion in a high temperature bath.

[0007]

SUMMARY OF THE INVENTION According to the present invention, by increasing the viscosity of molten metal that acts as a lubricant in a bearing sliding portion, the pressure is generated in the lubricant to support the shaft, prevent wear of the bearing, and reduce the life of the bearing. The object is to obtain a bearing device and a temperature control method thereof for lengthening the temperature.

[0008]

A roll bearing device for a roll in a molten metal bath according to the present invention is a roll bearing device which is used by being immersed in a molten metal bath, and a cooling device for a sliding bearing portion and / or a roll shaft. The above-mentioned problems are solved by the means characterized in that

At this time, it is preferable to provide a groove in the plain bearing portion.

Further, it is preferable to provide a temperature measuring device on the plain bearing portion and / or the roll shaft. Further, the method for controlling the temperature of the bearing of the roll in the molten metal bath of the present invention measures the temperature of the molten metal in contact with the sliding bearing portion and / or the roll shaft used by being immersed in the molten metal bath, and the result is obtained. The above-mentioned problem is solved by means characterized in that the temperature of the molten metal in contact with the slide bearing portion and / or the roll shaft is controlled by the cooling device provided on the slide bearing portion and / or the roll shaft based on the above.

[Function] The bearing used by being immersed in the molten metal bath is 4
The bearing is severely damaged because it is constantly immersed in a molten metal bath at a high temperature of 50 to 500 ° C. In particular, the wear of the bearing sliding portion is large, and this is because the viscous molten metal having a low viscosity of about 3.0 cp is the lubricant of the bearing, and the fact that the shaft and the bearing are in constant contact is a major cause. There is.

Therefore, if the viscosity of the molten metal acting as a lubricant in the bearing sliding portion is increased, the load capacity of the bearing is increased and the shaft can be supported by the lubricant, so that the shaft does not contact the bearing. Wear of the bearing can be prevented.

This temperature must be lowered in order to increase the viscosity of the molten metal lubricant. However, since the temperature of the molten metal bath needs to be kept at a temperature determined from the plating conditions of the steel strip, only the molten metal in the bearing sliding portion has to be lower in temperature than the surroundings.

In the present invention, the slide bearing portion and / or the roll shaft is provided with a cooling device. Further, it is possible to increase the cooling efficiency by providing a groove in the plain bearing portion to increase the contact area with the molten metal. In the present invention, the sliding bearing portion and / or
Alternatively, a temperature measuring device is provided on the roll shaft. The reason is that the viscosity of the molten metal changes depending on the temperature, so it must be kept in a specific range. The range is 420 to 4 for zinc
At about 40 ° C., it varies depending on the kind of metal, but a range of about melting point to melting point + 20 ° C. is preferable. Since the temperature of the bearing portion and the roll shaft is considered to be close to the molten metal temperature, the temperature may be measured at these locations. In the present invention, the temperature of the molten metal in contact with the sliding bearing portion and / or the roll shaft is controlled by the cooling device provided on the sliding bearing portion and / or the roll shaft based on the result obtained by the temperature measuring device. Accurate temperature control is necessary because zinc may be hardened due to overcooling by simply cooling the plain bearing portion and / or the roll shaft. FIG. 6 shows the ratio of molten zinc bath temperature to shaft life. As can be seen from the figure, the molten zinc bath temperature is 420 ° C.
When, the life of the bearing is maximized. However, even if the temperature of the molten metal itself is not measured, the temperature of the sliding bearing part and the roll shaft in contact with the molten metal is almost the same as the temperature of the molten metal in contact with it. The temperature of the molten metal in contact therewith may be replaced.

EXAMPLE An example of a bearing device for a roll in a molten metal bath according to the present invention will be described with reference to FIGS.

The bearing device of the present invention, as shown in FIG.
Bearing device 20 for a roll (for example, sink roll 3 or support roll 2) used by being immersed in a molten metal bath
In addition, as shown in FIG. 1-3, the sliding bearing portion 21 and / or the roll shaft 22 is provided with a cooling device 30.

The cooling device 30, as shown in FIGS.
The slide bearing portion 21 of the bearing device 20 is provided with the cooling water passage 23, the roll shaft 22 is provided with the cooling water passage 24, or both are provided with cooling water passages, and the cooling water is circulated through them.

By forcibly cooling the vicinity of the plain bearing portion 21 in this manner, the temperature of the molten metal bath 5 is increased to 470.
At ℃, the temperature of the molten metal bath in the vicinity can be lowered to 425 ℃.

As shown in FIG. 2, a heat insulating material may be provided as 25. By providing the heat insulating material 25, the cooling efficiency can be further improved.

Under the above structure and conditions, the thickness 0.3
A steel strip 1 having a width of −2.0 mm and a width of 600 to 1400 mm was continuously plated at a maximum line speed of 180 m / min. As a result, there was no damage during continuous use for 36 days.

Similarly, the stainless steel was sprayed and continuously plated under the same conditions using a conventional bearing having no cooling device. As a result, it became unusable due to wear in about 15 days.

Further, as shown in FIG. 3, the plain bearing portion 2
The groove 26 may be provided in the first. The groove 26 can increase the contact area with the molten metal and improve the cooling efficiency.

According to this embodiment, under the same conditions as described above, the molten metal in the vicinity of the slide bearing portion 21 can be lowered to 420 ° C. As a result of the continuous plating treatment, the bearing was not damaged even after being used for 45 days.

As shown in FIG. 4, the sliding bearing portion 21
If the seal is sealed by the seal plates 31 and 32 and the seal material 33, the molten metal in the seal portion does not flow out, and the cooling efficiency can be further improved. In addition, cooling may use other refrigerants than water.

The groove 26 has a rectangular cross section shown in FIG.
A cross-sectional shape such as a triangle or a semicircle may be used. FIG. 5 shows a method of controlling the temperature of the molten metal in the bearing sliding portion 35 by installing the temperature measuring device 34 in the bearing sliding portion 35, assembling the temperature control circuit 40, and adjusting the cooling water flow rate of the pump 50. FIG. When the molten metal in the bearing sliding portion was cooled without temperature control by the method shown in FIG. 5, zinc around the bearing solidified due to overcooling and a problem occurred. Therefore, the temperature control of the molten metal in the bearing sliding portion is performed by using the thermometer to set the target temperature 42.
When it was carried out at 5 ° C., the temperature could be controlled within the range of 425 ± 5 ° C. (when there were no grooves in the plain bearing portion). Moreover, when temperature control was similarly performed at a target temperature of 425 ° C. using a bearing having a groove in the plain bearing portion, the temperature was 425 ± 2 ° C.
It was controllable within the range.

[0025]

According to the present invention, wear due to direct contact between the shaft and the bearing can be prevented, and the life can be extended more than twice as long as the conventional one.

[Brief description of drawings]

FIG. 1 is a partial sectional front view of a bearing device for a roll in a molten metal bath according to the present invention.

FIG. 2 is a vertical sectional view taken along the line II-II in FIG.

FIG. 3 is a vertical cross-sectional view of a modification of FIG.

FIG. 4 is a sectional view of a sliding portion of the bearing of the present invention.

FIG. 5 is a schematic diagram of an apparatus for carrying out the method of the present invention.

FIG. 6 is a graph showing the relationship between the molten zinc bath temperature and the bearing life ratio.

FIG. 7 is a schematic explanatory diagram of conventional equipment in a molten metal bath.

8 is a partial cross-sectional view taken along the line VIII-VIII in FIG.

[Explanation of symbols]

 2: Support roll 3: Sink roll 4: Plating bath 5: Molten metal (zinc) bath 20: Bearing device 21: Sliding bearing part 22: Roll shaft 23, 24: Cooling water passage 25: Insulating material 26: Groove 30: Cooling Equipment 31, 32: Seal plate 33: Seal material 34: Thermometer 35: Bearing sliding part

Claims (4)

[Claims] 1. A bearing device for a roll in a molten metal bath, characterized in that in a bearing device for a roll used by being immersed in a molten metal bath, a cooling device is provided on a slide bearing portion and / or a roll shaft. 2. The bearing device according to claim 1, wherein the slide bearing portion is provided with a groove. 3. A bearing device for a roll in a molten metal bath according to claim 1, wherein a temperature measuring device is provided on the sliding bearing portion and / or the roll shaft. 4. The temperature of the molten metal in contact with the sliding bearing portion and / or the roll shaft, which is used by being immersed in a molten metal bath, is measured, and based on the result, the sliding bearing portion and / or the roll shaft is provided. A method of controlling the temperature of a bearing for a roll in a molten metal bath, comprising controlling the temperature of the molten metal in contact with the plain bearing portion and / or the roll shaft with a cooling device.