JPS583959A - Method and device for controlling weight of hot dip plated zinc in continuous zinc hot dipping - Google Patents

Abstract

PURPOSE:To decrease the variance in the weights of hot dip-plated zinc upon a strip by maintaing the distance from the surfaces of the strip and the leading ends of the nozzles of gas wiping devices at certain intended value by moving the gas wiping devices in correspondence to the oscillations of the strip. CONSTITUTION:A strip 5 which advances in an arrow direction and is stuck with zinc in a zinc plating bath 1 is passed between wiping nozzles 3 and 3, whereby the weights of hot dip-plated zinc are controlled. Here, the amplitudes of the strip 5 oscillating between pinch rolls 12 and top roll 4 are detected 9, and the detection signals thereof are fed to an arithmetic controller 10. The controller 10 calculates the amplitude of the strip 5 in the set position of the nozzles in accordance with said signals, and feeds the signals corresponding to these to servocontrol valve mechanisms 7. The mechanism 7 supplied with working fluid of high pressure controls the flow rates and directions of the working fluid according to the signals from the controller 10 and feeds the controlled working fluid to driving devices 6 consisting of oil hydraulic cylinders which in turn move and control the nozzles 3 in such a way that the spacings from the strip 5 are maintained at a constant set value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method and apparatus for controlling the amount of zinc deposited in hot-dip galvanizing equipped with a gas wiping device, particularly in a continuous bath dip galvanizing line equipped with a gas wiping device. The gas wiping device is moved accordingly and maintained at the target value of the distance between the strip surface and the nozzle tip of the gas wiping device - the tail, thereby reducing the variation in the amount of zinc deposited on the strip and keeping this amount of zinc at the target value. The present invention relates to a method and apparatus for controlling zinc deposition close to the value.

The distance between the strip surface and the nozzle tip of the gas wiping device is closely related to the amount of zinc deposited.

If this interval is too large, too much zinc will adhere, increasing the product cost. Furthermore, the distance between the strip and the gas wiping device changes due to the vibration of the strip, which is undesirable in terms of product quality 1nf, which causes the amount of zinc deposit to change.

Therefore, in a continuous hot-dip galvanizing line equipped with a gas wiping device, by keeping the distance between the nozzle tip of the gas wiping device and the strip surface constant and extremely small, it is possible to keep the amount of zinc deposited on the strip constant and extremely small. This was a major issue in operating a continuous galvanizing line.

For this reason, conventional measures have been taken, such as installing pinch rolls that sandwich the strip near the gas wiping device to suppress string vibration, and arranging strong magnets near the ends of the strip to suppress string vibration. has been taught.

However, in this conventional method, it is not possible to install a pinch roll or a magnet directly near the gas wiping device 1, so if the vibration (8) of Kanashi remains in the strip, it will cause damage to the strip and the gas wiping device. There was a limit to the reduction of the interval.

Thus, an object of the present invention is to provide a method and method that can maintain a constant and extremely small distance between the strip surface and the nozzle tip of a gas wiping device, thereby improving the quality of υ products, reducing costs, and increasing productivity. The goal is to provide equipment.

Furthermore, it is an object of the present invention to maintain a constant amount of zinc deposited on the strip by making it possible to adjust the distance between the nozzle tip of the gas wiping device and the strip surface online in a continuous hot-dip galvanizing line equipped with a gas wiping device. It is an object of the present invention to provide a method and apparatus that require minimal control.

The present invention is a method for controlling the amount of zinc deposited on a hot-dip galvanized strip lag using a gas wiping device, and in which the gas is This is a method for controlling the amount of zinc deposited in continuous hot-dip galvanizing, characterized by moving a wiping nozzle in a direction perpendicular to the strip surface (4) in accordance with the vibration of the strip sent out from the galvanizing tank.

The present invention also provides an amplitude detection device that detects the amplitude of vibration of a strip sent out from a galvanizing tank at an appropriate position, and calculates the width of the strip at a set position of 114 tK of a gas wiping nozzle from the detected amplitude. , movement of the gas wiping nozzle in a direction perpendicular to the strip in response to the calculated amplitude of the strip so as to maintain a distance between the nozzle tip of the gas wiping device and the surface of the strip at a constant set value; Continuous hot-dip galvanizing comprising: a calculation device for calculating the amount; and means for moving the gas wiping nozzle in a direction perpendicular to the strip in response to the calculated moving needle in -F. This is a zinc coating amount control device in the line.

As mentioned above, conventional measures have been taken to mainly suppress the vibration of the strip itself, and to set the gas wiping nozzle closer to the strip by the amount of the suppressed vibration. However, the strike IJ traveling at high speed
It is difficult to completely suppress the vibration of the knob, and therefore there is a limit to how close the gas wiping device can get to the strip.

Therefore, in the present invention, the position of the gas wiping nozzle is controlled to follow the vibration of the IJ knob to maintain the distance between the nozzle tip of the gas wiping device and the surface of the strip at the target value. It is something to do.

The gas wiping device used in this invention is a conventional device, and in the case of double-sided plating, it is provided in pairs around the running strip. It is preferable that the vibration detection position of the strip be as close to the gas wiping device as possible.

The position of the paired gas wiping device is moved in parallel according to the detected amplitude of the vibration of the strip IJ knob, and the strip is always maintained at the center of the paired gas wiping device. Good too. In this case, the distance between both gas wiping devices is preset. Of course,
The paired gas wiping devices may have their positions independently controlled. In that case, the zinc adhesion layers 1 on both sides of the strip can be changed independently of each other.

The invention will now be described in conjunction with the accompanying drawings.

The attached drawings show one embodiment of the present invention, and show a galvanizing bath 1. Dipping roll2. A continuous hot dip lead plating line consisting of a pair of gas wiping nozzles 8 and a top roll 4 is shown.

Zinc adheres to the strip 5 traveling in the direction of the arrow in the galvanizing bath 1, and then gas is jetted toward this strip in the gas wiping nozzle 8 to blow away the excess zinc. , finished to a predetermined adhesion thickness.

According to the present invention, a drive device 6 consisting of a hydraulic cylinder for moving the gas wiping nozzle 8, a servo pulp mechanism 7 for controlling hydraulic oil supplied to the drive device, and vibrations of the strip 5 are detected. A vibration detector 9, a calculation control device 10 for controlling the servo pulp machine (7) mechanism, and a cylinder position detector 11 for detecting movement of the gas wiping nozzle are provided.

The strip 5 ij l-is supported by a knob roll 4 and a pinch roll 12, and the supporting distance typically extends to several tens of meters. Therefore, the strip 5 vibrates as shown by the broken line in the figure. According to the present invention, the vibration state of the strip 5, that is, the amplitude of the vibration, is detected by the vibration detection device 9 provided near the gas wiping device 8, and this detection signal is sent to the arithmetic and control device 10. In the illustrated case, two magnetic metal piece position detectors were attached to the ends of the strip 50 in the width direction as vibration detectors. As a modification, a capacitive metal piece position detector, a distance meter using a laser, etc. may be used.

The arithmetic and control unit 10 calculates the vibration of the strip 5 at the set position of the gas wiping nozzle and the width of the strip 5 based on the target detection signal, and sends a signal corresponding to the calculated vibration of the strip 5 to the servo pulp. Send it to mechanism 7. For example, in the illustrated example, if the trip (8) vibrates to the left as shown by the dotted line 14, the paired gas wiping nozzles 3 are moved to the left as shown by the arrow. give a signal like this.

The servo pulp mechanism 7 is supplied with iV4 pressure hydraulic oil, and the i! The direction of the hydraulic oil is controlled in accordance with the signal from the device 10 and sent to the drive device 6 consisting of a hydraulic cylinder to move the gas wiping nozzle 8 in an appropriate direction. On the other hand, the cylinder position detector 11 attached to the gas wiping nozzle 8 detects the person moving the gas wiping nozzle, and the signal is sent to the arithmetic and control unit f1.
0 may be fed back to improve the follow-up control characteristics. In the illustrated example, an inductosin is used as the cylinder position detection word, but as a modification, a differential transformer, a magnescale, etc. may be used. In the figure, the signal system is indicated by a dotted line with an arrow.

The motor 15 for moving the gas wiping nozzle is used to roughly set the position of the gas wiping device, and is also used when moving it significantly for repairs, etc. As a modification, this motor can be used as a servo motor to move the servo pulp It may be used for position control instead of a mechanism.

The frequency response of the control system of the device of the present invention was 80 Hz when using the illustrated example configuration. In contrast, S) I
The photographing period of the J-tube is approximately α5 to 8 Hz, and therefore the gas wiping nozzle can be moved sufficiently in accordance with the vibration of the strip.

This invention will be further explained by examples.

Examples 1 to 3 Using the illustrated apparatus, this invention was carried out in the following eight ways.

Example 1 is an example of operation aimed at reducing the average coating weight on ordinary plating materials, Example 2 is an example of operation aimed at performing very thin plating, and Example 8 is an example of operation at high speed. be. The operating conditions and results are summarized in the table below. For reference, the results of a conventional method using pinch rolls to prevent strip vibration are also shown.

(Note) (A) Distance between the tip of the gas wiping nozzle and the strip surface (in order) (B) Gas ejection pressure of the gas wiping nozzle OV) (C) Average of zinc adhesion (up to 17m) Example of zinc adhesion!Minimum ~ Maximum (j'/rIL Riko) In the conventional method, the amplitude due to strip imaging was up to about 52 gates, so the pre-adjustment between the nozzle tip of the gas wiping device and the IJ knob surface. However, according to the present invention, in the case of Embodiment 1, the distance between the nozzle tip of the gas wiping device and the strip surface was set in advance even though the amplitude was the same. By setting the distance to 10 mm, we were actually able to reduce this distance to 8 to 12 gates.

Since we were able to maintain a spacing of 8 to 12 wn, we were able to accurately control the amount of plating to 92 to 9797 m. Even in the case of high-speed operation with high vibration frequency and amplitude in Example 8, a very uniform coating weight was obtained.

Thus, according to the present invention, since the gas wiping nozzle moves in response to the vibration of the strip, contrary to the conventional method, the distance between the strip surface and the nozzle tip of the gas wiping device can be significantly increased compared to the conventional method. can be narrowed down to As a result, it greatly contributes to improving product quality, reducing costs, and improving productivity.

Note that the present invention can also be implemented in combination with the conventional method using pinch rolls or magnets, in which case the vibration of the strip is further suppressed as much as possible, and the effects of the present invention are synergistically enhanced.

[Brief explanation of the drawing]

The accompanying drawings are schematic illustrations showing one embodiment of the present invention. 1: Galvanizing bath 2: Dipping roll 3: Gas wiping nozzle 4 Ni dot roll 5 Ni strip
6: Drive device 9: Imaging detection device 10:
Arithmetic control device patent applicant Sumitomo Metal Industries Co., Ltd. Patent attorney Akira Hirose

Claims (2)

[Claims] (1) A method for controlling the amount of zinc deposited on a hot-dip galvanized strip using a gas wiping device, in which the gas wiping nozzle A method for controlling the amount of zinc deposited in continuous hot-dip galvanizing, characterized by moving the strip in a direction perpendicular to the surface of the strip in accordance with the vibration of the strip sent out from a plating tank. (2) An amplitude detection device that detects the vibration amplitude of the strip sent out from the galvanizing tank at an appropriate position, and calculates the width of one arm of the strip at the set position of the gas wiping nozzle from the detected amplitude, and Calculating the movement of the gas wiping nozzle in the direction perpendicular to the strip in response to the calculated amplitude of the strip so as to maintain the distance between the nozzle tip of the wiping device w and the strip surface at a constant set value. and means for moving the gas wiping nozzle in a direction perpendicular to the strip in accordance with the calculated number of movements. Control device.