JPH09263919A - Hanger for support roll of hot dip coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the unequal rotation of support rolls which guide a steel strip in a coating bath by forming hangers for supporting these support rolls as hollow hangers and housing a low melting metal into the hollow parts. SOLUTION: The hangers 6 for the support rolls of this hot dip metal coating device are mounted at circumferential fixtures by means of hanger supporting bodies 8. The hangers 6 are formed to a cylindrical shape and the bottoms thereof are closed airtightly, by which the hollow hangers are formed. The low melting metal 7 is housed into these hollow parts. When the hangers 6 are charged into the plating liquid 2, the low melting metal housed in the hollow parts melt. The hangers 6 enclosing the molten metal exhibit the effect of absorbing the vibration occurring in the co-rotation of the support rolls 4, thereby preventing the vibration of the strip 1. The low melting metal which has the m. p. lower by about 200 to 300 deg.C than the temp. of the coating bath and bas the sp. gr. difference from the coating bath larger by about 1.0 to 2.0 is preferably used as the low melting metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support roll for use in a hot dip metal plating apparatus, which is immersed in a hot dip metal bath, and which guides a steel strip passing through the hot dip bath, The present invention relates to a hanger for a support roll.

[0002]

2. Description of the Related Art Surface-treated materials obtained by performing hot dip galvanizing or hot dip galvanizing such as hot dip galvanized aluminum on the surfaces of metal sheets such as steel sheets have the property of being excellent in corrosion resistance. Has been prized in such fields. The production of such a hot-dip plated metal sheet is generally carried out by an apparatus provided with a pair of support rolls 4 at a position where the sink roll 3 in the bath exits, as schematically shown in FIG. . This support roll is provided mainly for the purpose of making the plating thickness uniform on the surface of the metal plate 1. Normally, the support roll is driven and constantly immersed in the high temperature plating bath 2 in order to prevent slip flaws. It rotates and guides the steel plate that passes through the plating bath. For the support of this support roll, in most cases, as shown in FIG.
As shown in (a), a support roll was attached to the tip of the cantilevered hanger 5 and the other end was supported outside the bath. Further, the structure of the conventional hanger uses a solid material as shown in the cross section (AA cross section) of FIG. 2 (b) or (c).

As described above, the main purpose of this support roll is to make the plating thickness uniform. Therefore, it is ideal to rotate the support roll while suppressing whirling and vibration as much as possible. However, when operating with the plating system equipped with the above-mentioned conventional hanger, in reality, there is play in the sliding bearing, vibration due to driving force, vibration due to insufficient rigidity of the hanger, etc. ) Occurred. Therefore, the vibration of the strip caused by the uneven rotation is large, and it is difficult to make the plating thickness uniform. The "runout" means a phenomenon in which the roll shaft core moves due to rotation.

Therefore, many attempts have been made so far in order to suppress the above-mentioned rotation unevenness and eventually the vibration of the strip. For example, Japanese Patent Application Laid-Open Nos. 3-219061 and 6-27647 disclose improvements in the driving method, and Japanese Patent Application Laid-Open No. 5-320847 discloses a method for attaching a vibration preventing device to a strip.
Japanese Patent Application Laid-Open No. 4-124253 proposes a method of adjusting the pushing amount or line speed of a hanger, and Japanese Patent Application Laid-Open No. 4-124253 proposes a technology of employing a ceramic rolling bearing.

[0005]

However, in the techniques disclosed in Japanese Patent Application Laid-Open Nos. 3-219061 and 6-27647, the drive spindle tilts when driven from outside the bath, and the universal joint is placed in the bath. When the (Cardan joint) is used, a component force other than the force for rotating the roll (pure rotation torque) is generated, and there is a problem that whirling cannot be prevented. In the technique disclosed in Japanese Patent Laid-Open No. 5-320847, the apparatus is extremely complicated and expensive, and a considerably large installation space is required. Therefore, the vibration of the strip cannot be efficiently prevented in the vicinity of the wiping nozzle. was there. In addition, JP-A-6-172
The technique disclosed in Japanese Patent No. 13 has a problem in that the line speed may be limited and may not be industrially effective. Further, in the technique disclosed in Japanese Patent Laid-Open No. 4-124253, the life of the ceramic rolling bearing is indefinite, and even if the vibration of the bearing is monitored,
There was a problem that it was suddenly destroyed and lacked in reliability.

Therefore, the present invention solves the above-mentioned problems of the prior art and prevents uneven rotation (run-around, vibration) of the support roll of the molten metal plating apparatus, thereby preventing vibration of the strip. The purpose is to develop a hanger for a support roll in a bath of a hot dip metal plating machine.

[0007]

In order to solve the above-mentioned problems, the inventor has earnestly studied the structure of a hanger for a support roll, and as a result, has developed a hanger having an extremely effective structure for preventing uneven rotation. Came to. That is,
INDUSTRIAL APPLICABILITY The present invention is a hanger for supporting a support roll for guiding a steel strip which is immersed in a molten metal plating bath and has a hollow portion containing a low melting point metal. A hanger for a support roll of a molten metal plating apparatus, which is characterized in that Further, the present invention is the hanger for a support roll, which contains a low melting point metal having a melting point lower than the temperature of the plating bath by 200 to 300 ° C.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A hanger for a support roll of a molten metal plating apparatus according to the present invention is characterized in that a hanger main body is hollow and a low melting point metal is accommodated in the hollow portion. FIG. 3 shows an example of a hanger according to the present invention. FIG.
In (a), the hanger 6 is attached to a surrounding fixed object by a hanger support 8. And hanger 6
3 has a tubular shape as shown in FIG. 3B showing the BB cross section, and the bottom is closed in an airtight state to be hollow. The low melting point metal 7 is housed in the hollow portion of the hanger.

The low melting point metal must be a metal having a melting point lower than the temperature of the plating bath, and basically any metal (including alloy) may be used as long as this condition is satisfied. Among them, the melting point of the metal is preferably lower than the temperature of the plating bath by about 200 to 300 ° C., and the difference in specific gravity from the plating bath is preferably about 1.0 to 2.0, and further corrosion etc. Therefore, it is desirable that the hanger material is not damaged. The amount of the low melting point metal accommodated may be appropriately determined depending on the plating equipment used, but it is desirable to adjust the liquid level of the molten metal in the hanger to be higher than the plating bath surface by about 0 to 200 mm.

When this hanger is charged into the plating bath,
The low melting point metal contained in the hollow portion melts. And
Since the hanger containing the molten metal has an effect of absorbing the vibration caused by the whirling of the roll, the vibration of the strip can be prevented. If the plating operation is performed while maintaining this state, even if the roll vibrates as the strip travels, the low melting point metal of the liquid inside the hanger absorbs the vibration, and eventually vibration of the roll can be prevented. Although the plating solution is also a liquid, the plating solution is agitated by the rotation of the roll and the running of the strip, and acts to vibrate the hanger itself. Therefore, in the conventional solid steel hanger, this vibration is directly received. On the other hand, as in the present invention, in the hanger having the liquid metal inside, since it acts to suppress the vibration due to the inertia of the liquid metal, the vibration preventing effect of the roll which cannot be obtained by the conventional hanger is obtained. Obtainable.

[0011]

Example A hanger according to the present invention was applied to a continuous hot dip galvanizing facility. 240 mmφ support roll in the bath
The hanger is 2000 mm long, and the hanger has the same structure as that of FIG. 3, and the hanger is made of SUS316L and has a thickness of 30 mm.
The box structure was 50 mm × 200 mm. A low melting point metal (melting point: 150 ° C.) mainly composed of tin and bismuth is approximately 200 mm from the plating solution surface in the hollow part of the hanger.
It was housed up to the top. Using the apparatus as described above, a plated steel sheet having a size of 0.2 mm thick and 1400 mm wide is
The plate was passed at a line speed of 150 m / min. As a result, the plate vibration in the wiping nozzle portion was 0.35 mm (one-sided amplitude) on average. On the other hand, the plate vibration in the operation using the conventional solid hanger was 1.4 mm (one-sided amplitude) on average.
As is clear by comparing the plate vibration values of the two, it is understood that the hanger according to the present invention exhibits a plate vibration suppressing effect as compared with the conventional hanger.

[0012]

As described above, according to the present invention, the hanger main body is hollow and the low melting point metal is accommodated in the hollow portion. Therefore, the rotation unevenness of the support roll is prevented regardless of the roll driving method. It is possible to prevent the vibration of the strip due to the whirling of the support roll. Moreover, according to the present invention, since the structure is extremely simple, it is possible to prevent the vibration of the strip with high reliability at a low cost without lowering the line speed.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an arrangement of rolls in a molten metal plating apparatus.

FIG. 2 is a view showing a conventional hanger.

FIG. 3 is a view showing a hanger of the present invention.

[Explanation of symbols]

 1 Metal Plate (Strip) 2 Plating Bath 3 Sink Roll 4 Support Roll 5 Hanger 6 Hanger 6a Hanger Bottom 7 Low Melting Metal 8 Hanger Support

Claims (1)

[Claims] 1. A hanger for supporting a support roll for guiding a steel strip which is immersed in a molten metal plating bath, and which has a hollow portion containing a low melting point metal. A hanger for a support roll of a hot dip metal plating device, which has.