JPH05287478A - Method and apparatus for producing molten metal plated strip - Google Patents

Abstract

(57) [Summary] [Objective] The present invention relates to a method and an apparatus for producing a continuous hot-dip galvanized metal strip, which aims to reduce the variation in the amount of plating by correcting the shape of the plate at the wiping nozzle. To do. [Composition] A wiping gas is blown to the strip that has passed through the molten metal plating bath to detect the amount of warp in the width direction of the strip in the vicinity of the wiping nozzle in a molten metal plating line that controls the amount of plating adhesion. The positions of the support roll and pot roll are adjusted to straighten the strip shape to obtain a uniform amount of plating by automatic control. Further, the strip shape is roughly adjusted by adjusting the position of the support roll, and then the strip shape is finely adjusted by adjusting the position of the pot roll.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a continuous high-speed hot-dip galvanized metal strip having a uniform coating weight and a beautiful appearance by adjusting the coating weight of the strip by a gas blown from a wiping nozzle in hot metal plating. A method and apparatus.

[0002]

2. Description of the Related Art In a molten metal plating line, a predetermined amount of adhered plating is obtained by spraying a high-pressure wiping gas from a wiping nozzle to a strip that has passed through a plating bath to wipe excess plating. At this time, if the strip has a warp in the width direction in the wiping nozzle portion, the distance between the wiping nozzle and the strip becomes non-uniform, so that the plating deposition amount varies, and a uniform plating deposition amount cannot be obtained. That is, it is very important to stabilize the strip shape at the wiping nozzle portion.

Conventionally, various attempts have been made to correct the warp of the strip in the width direction, and a technique for forcibly correcting the strip shape of the wiping nozzle by applying an external force, for example, Japanese Patent Laid-Open No. 52-111839. A method using a magnet roll disclosed and a suction method using an ejector disclosed in JP-A-58-77562 are known. Further, as a method of straightening with a roll, Japanese Patent Application Laid-Open No. Sho 62-62 is known.
No. 30865, a method of adjusting by a pushing amount of a pair of snap rolls installed between a pot roll and a wiping nozzle, and between the snap roll and the pot roll disclosed in JP-A-1-268852. Further, a method is known in which a collecting roll is provided and the shape of the strip is corrected by the pushing amount of the collecting roll.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Since the method using a magnet roll disclosed in Japanese Patent No. 39 and the suction method using an ejector disclosed in Japanese Patent Laid-Open No. 58-77562 utilize external force, a force generator for that purpose is used. It is necessary and both of them are non-contact and give an external force to the strip, which is inefficient and therefore the line speed that can be supported is low, and conversely it is very large in order to be able to support high line speeds. Magnetic force and attractive force are required, which is not realistic.

Further, a method disclosed in Japanese Unexamined Patent Publication No. Sho 62-30865, in which adjustment is performed by pushing in a pair of snap rolls installed between a pot roll and a wiping nozzle, and Japanese Unexamined Patent Publication No. 1-268852 are disclosed. In the method in which a collecting roll is further provided between the snap roll and the pot roll, and the strip shape is corrected by the pushing amount of the collecting roll, the diameter of the snap roll and the collecting roll is small. Since the bending radius of the strip is small, the amount of change in the warp of the strip becomes very large with respect to the amount of adjustment of the pushing amount, and it is difficult to finely adjust the warp correction, and a sufficient correction effect may not be obtained. Furthermore, the warp shape in the width direction is
Since it depends on the plate width, original plate shape, tension, and roll wear amount, it is necessary to correct the warpage under each condition.At this time, if fine adjustment is difficult, it will be a burden on the operator to take adjustment time each time, In addition, the strip in the meantime becomes a defective material, resulting in poor yield, and there is a problem that automation is difficult.

[0006]

The present invention advantageously solves the above-mentioned problems of the prior art, and its gist is as follows: (1) Wiping gas is blown to the strip that has passed through the molten metal plating bath; In the molten metal plating line that adjusts the amount of plating adhered, the amount of warp of the strip in the width direction near the wiping nozzle is detected, and the positions of the support roll and pot roll are adjusted based on the data of the amount of warp. Method for producing hot-dip galvanized strip. (2) In the method described in the above item (1), the rough adjustment of the strip shape is performed by adjusting the position of the support roll, and then the fine adjustment of the strip shape is performed by adjusting the position of the pot roll. Strip manufacturing method. (3) A sensor installed in the vicinity of the wiping nozzle to detect the warp of the strip in the width direction, and the amount of warp of the strip in the width direction is calculated based on the detected data to support the optimum strip shape, that is, flatness. A control arithmetic unit that gives adjustment commands for the position of contact with the strip to the rolls and pot rolls, and a roll stand on which the positions of the support roll and pot roll can be independently adjusted according to commands from the control arithmetic unit A molten metal plating strip manufacturing device consisting of a roll position adjusting mechanism.

[0007]

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment apparatus shown in the drawings. FIG. 1 shows a sectional view of the hot-dip strip production line. In the upper part of the figure, a block diagram of a control system of the amount of plating adhered according to the present invention is also shown.

In the hot-dip strip production line, the strip 1 enters the plating bath in the hot-dip plating pot 4 through the turndown roll 2 and the snout 3, and the pot roll 5 in the bath changes the line direction to change the line direction in the vertical direction. At the point of exiting the pot bath while supporting the plate passing line, unnecessary plating is wiped by the high-pressure gas blown out from the wiping nozzle 7, and the thickness of the plating adhered to the strip surface is controlled.

In the present invention, a distance sensor 8 for measuring the shape of the strip in the width direction is installed directly above the wiping nozzle 7, and the measurement data is transmitted to the control device 9. To the control device 9, the current operation data has been sent from the operation management system 10 together with the shape data in the strip width direction sent from the distance sensor 8. The present strip plate thickness, width, tension, roll diameter Of the support roll 6 by comprehensively processing the data of the
And the shift amount of the pot roll 5 is calculated. The calculation result is
It is sent as a shift command to the shift mechanism 11 of the support roll 6 and the shift mechanism 12 of the pot roll 5, and each shift mechanism performs roll shift based on the command value. Even during the shift operation, the distance sensor 8 measures the shape of the strip in the width direction, and the shift operation can be performed in real time. By using the support roll 6 and the pot roll 5 together, a large amount of warp can be corrected by using the support roll 6
The final fine adjustment is performed with the pot roll 5. Since the pot roll has a large diameter and thus has a small correction force, since the rough adjustment is performed by the support roll 6, the shape of the strip can be finely adjusted by shifting the pot roll 5. Further, when the pot roll 5 is shifted, the pass line from the turndown roll 2 to the pot roll 5 changes, but it does not come into contact with the snout 3.

The present invention will be described in detail below with reference to method examples. Continuous hot dip galvanization of strips (plate width: 1500 mm, plate thickness: 1.0 mm) was performed using the above-described apparatus of the present invention. Line speed is 120
The mpm and the tension are 1.2 ton / m. The amount of warp of the strip in the width direction was measured by an eddy current type distance sensor, which was installed in the width direction immediately above the wiping nozzle. The detection accuracy of this sensor is ± 0.1 mm. 2 and 3 are graphs showing the amount of warp of the strip when the support roll is pushed in 0 to 23 mm and the pot roll is pushed in 0 to 135 mm under these conditions. The support rolls can be arranged either vertically. Here, the warp amount of the strip is expressed as (maximum value-minimum value) = warp amount from the measurement data of the five distance sensors. In the figure, the ratio between the shift amount and the warp amount is represented as a correction effect index K. It can be seen from the graph of FIG. 2 that although the warp correction effect of the support roll is great, the change is rapid and adjustment is difficult. It can be seen from FIG. 3 that the correction with the pot roll is small, but the correction tendency is easy to understand and finely adjusted. FIG. 4 shows the result of straightening the strip by properly using the support roll and the pot roll, and it was possible to flatten the measurement accuracy range of the sensor. In addition, due to this, the variation in the amount of plating adhered in the width direction of the past was ± 40 g / m ² , but was ± 5 g.
It was possible to hold down within / m ² .

[0012]

As described above, according to the present invention, it is possible to easily finely adjust the warp in the strip width direction at the wiping nozzle portion in the hot-dip strip manufacturing apparatus, which not only improves the quality of the plating strip. Not
The automation can be easily realized, and the operator does not have to work in a high heat environment around the pot, which leads to safety of work, and the line speed can be increased, which is a remarkable result.

[Brief description of drawings]

FIG. 1 is a cross-sectional view and block diagram illustrating a hot-dip strip production line and a control system of the present invention.

FIG. 2 is a diagram showing a shift amount of a support roll and a pot roll and a warp correction effect, respectively.

FIG. 3 is a diagram showing shift amounts of a support roll and a pot roll and a warp correction effect, respectively.

FIG. 4 is a diagram of a warp in a plate width direction when a support roll and a pot roll are combined and straightened.

[Explanation of symbols]

1 ... Strip 2 ... Turndown roll 3 ... Snout 4 ... Hot dip pot 5 ... Pot roll 6 ... Support roll 7 ... Wiping nozzle 8 ... Distance sensor 9 ... Control device 10 ... Operation management system 11 ... Support roll shift mechanism 12 ... Support Roll shift mechanism

Continuation of the front page (72) Inventor Tsutomu Haeno 1 Kimitsu, Kimitsu-shi Kimitsu Works, Nippon Steel Corporation

Claims (3)

[Claims] 1. A molten metal plating line for spraying a wiping gas onto a strip which has passed through a molten metal plating bath to adjust the amount of plating adhered, and detects the amount of warp of the strip in the width direction in the vicinity of the wiping nozzle. A method for producing a molten metal plating strip, characterized in that the positions of the support roll and the pot roll are adjusted based on the data. 2. The method according to claim 1, wherein the strip shape is roughly adjusted by adjusting the position of the support roll,
Then, a method for producing a molten metal-plated strip, characterized in that the shape of the strip is finely adjusted by adjusting the position of the pot roll. 3. A sensor installed near the wiping nozzle to detect the warp of the strip in the width direction, and the amount of warp of the strip in the width direction is calculated based on the detection data to obtain an optimum strip shape, that is, a flat shape. A control arithmetic unit that gives an adjustment command for the position of contact with the strip to the support roll and the pot roll, and a roll stand on which the positions of the support roll and the pot roll can be independently adjusted by the command from the control arithmetic unit. Apparatus for producing a molten metal plating strip, which comprises a roll position adjusting mechanism.