JPH01219192A - Method for detecting sheet breakage in continuous electroplating - Google Patents

Abstract

PURPOSE:To eliminate the malfunction due to the slippage, slackening, inching, etc., of a steel sheet and to rapidly and surely detect the sheet breakage by combining the detection values of the plating voltage in electroplating and the variations in the width and tension of the steel sheet, and making a calculation. CONSTITUTION:In the continuous electroplating of a steel sheet 1, the plating voltage in the plating section is detected through a rectifier, a first abnormality detection signal A is outputted when the voltage detection value exceeds the voltage upper-limit set value. The sheet width is detected on the inside and outside of the plating section, and a second abnormality detection signal B is outputted when the width becomes smaller than the width lower-set value. The tension of the sheet 1 is detected by a tensimeter, and a third abnormality detection signal C is outputted when the tension variation exceeds the upper- limit set value except when the sheet is inched on the inlet side of the plating section. The logical product A.B.C of the signals A, B, and C is calculated, the sheet breakage is detected when calculated logical value is equal to 1, and the driving of the line and the plating current are immediately stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for detecting breakage of a plate-like body in a plating section in continuous electroplating equipment for plate-like bodies such as steel plates.

(Prior Art) Breakage of plates in the plating tank of electroplating equipment occurs due to poor welding at the entrance section, interference with the edge mask device due to temporary meandering, and the like.

In this case, unless the line is stopped and energized immediately, equipment such as electrodes and energizing rolls will be damaged, requiring a long shutdown. On a line with a complex structure like an electric menki line, how accurately and quickly a plate break can be detected has a significant impact on the time required for subsequent recovery, so it is important to detect plate breaks reliably and quickly. There is a strong desire to develop a method to do so.

Conventional methods for detecting plate breakage include the following methods.

■Method of measuring the speed difference of the prydle before and after plating SEF 91F and detecting plate breakage if the speed difference exceeds the upper limit.

■A method that calculates the difference in the cumulative length of prydle before and after plating safety 93, and detects plate breakage if the upper limit is exceeded.

■Method of measuring the tension of a steel plate and detecting plate breakage when the tension fluctuation value becomes large.

■A method of detecting plate breakage by using an earth detection device to detect contact between the plate and the detection device due to plate sag.

In addition, although the above methods (■ to ■) are not originally intended for detecting plate breakage, Japanese Patent Application Laid-Open No. 58-1075
There is a publication No. 00. This calculates the product of the resistivity between the electrodes and the distance between the electrodes from the plating current detection value, voltage detection value, and effective area setting value, and compares this with the upper and lower limit setting values to determine whether sparks occur due to abnormal proximity between the electrodes. This prevents power wastage due to abnormal disconnection. Although the method of this publication is particularly aimed at detecting changes in the distance between electrodes in soluble electrodes, it is thought that it can also be applied to detecting plate breakage.

(Intelligence B to be solved by the invention) The conventional method for detecting plate breakage has the following problems. Misdetection occurs due to slips, and it is also difficult to set the upper limit to an appropriate value. In the detection method (2) using tension fluctuation values, tension fluctuations and slippage of the steel plate during forward and reverse jogging in the entry section cause false detection. Furthermore, the method (2) using a ground detection device has the problem of erroneous detection due to poor insulation of the detection device and sagging of the plate during acceleration and deceleration.

Therefore, an object of the present invention is to provide a quick and reliable method for detecting plate breakage without the risk of malfunctions due to slipping, sagging, inching, etc. of a plated plate such as a steel plate.

(Means for Solving the Problem) In order to achieve the above object, the present inventor has conducted research and obtained the following idea. False detections can occur for various reasons.

However, the causes of false detection differ depending on each plate breakage detection method. In other words, a phenomenon that causes false detection with one detection method does not cause false detection with another detection method. Therefore, if a plurality of detection methods are combined and used at the same time, and the shortcomings of each method are compensated for, reliable plate breakage detection should be possible. Based on this idea, we conducted further research, determined a specific combination of mutually complementary detection methods, and also improved the detection methods that are the elements of the combination, thereby completing the present invention.

In this way, the gist of the present invention is that, in equipment that continuously electroplates plate-shaped bodies, a) a first abnormality detection signal A is output when the detected voltage value in the plating section exceeds the voltage upper limit setting value; b) Detecting the board width at the upper comb 3 of the plate and outputting the second abnormality detection signal B when the board width becomes less than the lower limit set value of the board width; C) Detecting the board width in the plating section. detects the tension of
The third abnormality detection signal C is generated when the tension fluctuation exceeds the tension fluctuation upper limit setting value except when the plating section is inching on the human side.
d) Calculating the logical product A-B-C of the abnormality detection signals A, B, and C, and detecting plate breakage when the value of the signal A-B-C is a logical value of 1. This is a method for detecting plate breakage in continuous electroplating, comprising the steps of ) to d).

(Function) In the present invention, continuous monitoring of plating voltage during electroplating energization a
) and steel plate width detection b) to detect plate breakage, there is no false detection due to slipping, sagging, etc. In addition, in tension fluctuation detection C), the plated section entry side positive
Erroneous detection is prevented by excluding reverse inching from the detection conditions. Accurate plate breakage detection is possible by taking the logical product A-B-C of the detection signals A, B, and C.

Further, the operation of the present invention will be explained in detail as follows.

a) When detecting a voltage abnormality using a Menki cell, calculate the current density from the plating current detection value and the plate width data, and determine the voltage upper limit set value according to the current density.

The plating current density is calculated based on the width of the steel plate, the length of the electrode, and the plating current detection value. The relationship between the plating current density and the plating voltage is expressed as a constant linear relationship during normal operation. Since current is controlled in plating equipment, if a plate breaks and the plate becomes blank, the voltage will be excessive, and
It deviates significantly from the above linear relationship. Therefore, by detecting the plating voltage and comparing it with the upper limit set value determined from the above relationship, a signal A indicating plate breakage is output.

On the other hand, when detecting voltage abnormalities in pretreatment cells,
For example, set 110% of the rated voltage as the voltage upper limit,
An abnormality is detected when the detection voltage exceeds this upper limit value.

b) The width of the steel plate is detected using a fixed plate edge detector outside the plating tank, and a plate edge detector that follows the plate edge inside the plating tank. When the plate width calculated from these plate end positions becomes less than or equal to the lower limit setting value, a signal B indicating plate breakage is output. Note that this lower limit setting value may be set to O. In this case, the signal B is output when the detection plate width becomes 0.

C) The tension in the plated section remains constant during normal operation, but transient tension fluctuations occur when the plate breaks.

If the tension fluctuation detected by the tension meter exceeds the upper limit setting value other than during inching on the entry side, a signal C indicating plate breakage is output.

d) Logical product A- of these signals A, B, and C indicating plate breakage
Accurate plate breakage detection is performed by B-C.

(Example) Next, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the overall configuration of an embodiment in which the plate breakage detection method of the present invention is applied to continuous electroplating equipment for steel plates. The plating section is equipped with a large number of plating tanks, and the steel plates 1 are continuously plated. Although not shown in FIG. 1, the steel plate is supplied to the plating section from a payoff reel via a prydle roll, an inlet looper, and a prydle roll. On the other hand, the steel plate that has left the plating section passes through a prydle roll, a heat treatment furnace, a tension roller, an exit looper, and a prydle roll in order, and is then wound onto a take-up reel.

The method of the present invention detects plate breakage using the AND signal A-B-C of a signal A indicating an abnormality in plating voltage, a signal B indicating an abnormality in plate width, and a signal C indicating an abnormality in tension. The method for forming each signal will be explained in sections below.

Term A: Plating] FIG. 2 is a block diagram showing the configuration of a device for forming signal A indicating voltage abnormality.

The steel plate 1 travels through a plating cell 4 via an energized roll 2 and a dipping roll 3, and is continuously coated between electrodes 5. Plating current is supplied from a rectifier 7 via a bus bar 6 and is controlled by a current control device 8. on the other hand,
The current between the electrodes 11 in the pretreatment cell 10 is passed through the rectifier 1
2 and controlled by a current control device 8.

The current value I and the voltage value ■ of each rectifier 7.12 are output from the current control device 8 to the arithmetic device 13.

When forming the signal A based on the plating voltage and plating current detected values in the Menki cell, the arithmetic unit 13 follows the following procedure.

As shown in the graph of FIG. 3, the normal plating voltage (2) can be expressed by the regression formula (%) using the current density J as an independent variable. However, Kg: constant J: current density (^/dm") V plating voltage (V) Therefore, by regression analysis in advance, tl in Methoxel 4
Determine the constant of equation 1, for example 1′ −
K.

By setting x, l -4X+C, (C: an appropriate constant), use K+ and Kg to make the constant 1゛ (≧1).

Determine 2゛ (〉 is 2) for v, I=, 'J+,' ---. Set the values v, l determined by (2) as the upper limit of the voltage ■ for the plating current density J ( Figure 3).

Therefore, the calculation device 13 first calculates the current density J from the plating current detection value 11 electrode length (fixed value) and plate width W using the following formula: J=1/LxW...(3) Next, (3) The current density detection value J obtained from the equation is substituted into the equation (2) to calculate the voltage upper limit value VM.

Furthermore, the plating voltages ■ and ■8 are continuously compared, and a signal A is output under the condition that V>V while the plating current is flowing.

On the other hand, when forming the signal A based on the voltage value in the pretreatment cell 10 that performs pickling, etc., the energization method is different from that of the Menki cell 4, so the signal A is formed based only on the detected voltage value ■.

That is, for example, if 110% of the rating is set as the voltage upper limit value vM', and ■ is the pretreatment cell electrode voltage, then during energization v>
A signal A is output under the conditions of v and I'.

Signal B: Detection of board width abnormality Next, the procedure for forming signal B indicating a board width abnormality will be explained with reference to FIG.

The plate edge detectors 14a and 14b are composed of imaging devices, for example, and detect the plate edge position of the steel plate 1 outside the menki cell. Similarly, the plate edge detectors 14c and 14d detect the plate edge position of the steel plate l within the Menki cell. Plate width detector 15
a, 15b are board width W1,
W, is calculated and output to the arithmetic unit 16. Detectors and board width detectors are installed every 2 to 4 cells, and are fixed outside the cell and movable to follow the board edge inside the cell.

15c in FIG. 4 is an example of a plate width detector of another cell.

The calculation device 16 sets the plate width W aw W c calculated by each plate width detector 15 a to 15 c to a lower limit set value W o (for example, W.

= 0), two consecutive calculation board widths Wi (i = a
When Wi≦Wo ...(4) holds true for l b, ...+c), or when the detection plate width Wi (i-a+b
l...+c), a signal B is output when any one of them satisfies equation (4).

Signal C: Variation FIG. 5 is a block diagram of a device that generates signal B based on tension fluctuations detected by tension meter 17a.

During normal operation, the steel plate 1 is driven with a constant tension by tension control using priddle rolls.

゛ Tension installed behind the entry side priddle roll 1a! H7a consists of a roll cell and detects the inlet tension of the plating section. Tension meter amplifier 17b amplifies the signal from tension meter 17a and outputs a tension value to tension control device 18 and calculation device 19. The calculation device 19 continuously monitors the tension value for each scan, and when the absolute value of the difference (T+Tz) between successive scan values T, , Tt exceeds the tension fluctuation upper limit value ΔT + e m x, that is, lT, -
A signal C3 is generated when Tl>ΔT ++tax holds true.

Incidentally, tension fluctuations may occur during acceleration and deceleration of the entry section, particularly during forward and reverse inching. In order to prevent malfunctions due to this, it is necessary to input the entry side inching signal from the line main control device 20 to the calculation device 19 and remove it from the plate breakage detection conditions. Therefore, the arithmetic unit 19 outputs the logical product of the above-mentioned signal C2 and the inching signal as the signal C: C=C, -D Then, the logical product A・B−C of the signals A, B, and C calculated as above is calculated, and this is outputted to the line main controller 20 as the plate breakage signal E: E=A −B −C In response to the plate breakage signal E, the line master controller 20 stops the line drive motor 22, and also turns off the current command gate of the plating current controller 23, thereby stopping the supply of plating current.

(Effects of the Invention) As described above, the present invention eliminates the false detection of each signal by taking the logical product of the three types of abnormal signals: excessive plating voltage, no plate determined from the plated plate width, and abnormal tension fluctuation. Three types of signals are combined to detect plate breakage. Therefore, plate breakage can be detected without the risk of malfunction, and damage to equipment and long-term shutdowns can be prevented.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the overall configuration of the present invention; Figure 2 is a block diagram showing the formation of a voltage abnormality detection signal in the present invention; Figure 3 is a diagram showing the upper limit value and regression equation for voltage abnormality detection. A graph showing the relationship; FIG. 4 is a block diagram showing the formation of a plate width abnormality detection signal in the present invention; and FIG. 5 is a block diagram showing the formation of a tension fluctuation abnormality signal and a plate breakage signal in the present invention. . 1: 11 plate 2: Current roll 4: Methoxel 5: Electrode 7: Rectifier 8: Current control device 10: Pretreatment cell 11: Electrode 12: Rectifier 13: Arithmetic device 14a to 14
d: Fi end detector 15a to 15c: Board width detector 16: Arithmetic device 19: Arithmetic device 20: Line main control device 21: Synthetic circuit L4 concave

Claims (1)

[Claims] In an equipment for continuously electroplating a plate-shaped body, a) a first abnormality detection signal A is output when a voltage detection value in the plating section exceeds a voltage upper limit setting value; b) ) Detecting the plate width in the plating section and outputting a second abnormality detection signal B when the plate width becomes less than the lower limit set value of the plate width; c) Detecting the tension of the plate in the plating section;
The third abnormality detection signal C is generated when the tension fluctuation exceeds the tension fluctuation upper limit set value at a time other than when the plating section enters the plating section.
d) Calculating the logical product A, B, and C of the abnormality detection signals A, B, and C, and detecting plate breakage when the values of the signals A, B, and C are logical 1; A method for detecting plate breakage in continuous electroplating, comprising the steps of ) to d).