JP2904892B2 - Method and apparatus for suppressing stray current - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a stray that occurs in a series of processing lines provided with a device for continuously performing electrolytic treatment such as plating and descaling of a metal strip. The present invention relates to a stray current suppressing method and a stray current suppressing method capable of suppressing a current to prevent damage to various devices and devices in the metal strip and the processing line due to the stray current.

[Conventional technology]

Conventionally, in an electrolytic treatment apparatus composed of only one tank, since the positive electrode and the negative electrode are symmetrically arranged in the same tank, the potential difference of the metal band between the entrance and exit of the tank is extremely small. As a result, almost no current (otherwise called a stray current) flowing through the current path was generated.

In addition, even if it is composed of a single tank, an electrolytic treatment apparatus in which the potential difference of the metal band between the entrance and exit of the tank is large depending on the electrode arrangement, or a metal construction consisting of a plurality of tanks and between the entrance and exit of the apparatus In a processing line having an electrolytic processing device having a large potential difference between the bands, stray current is generated by electrically insulating a metal band and a device passing through the metal band with an insulating material (eg, rubber). Was preventing.

However, if the existing processing line has an electrolyzing device with a large potential difference between the incoming and outgoing sides of the metal strip in a line facility that has a plate passing device that is not electrically insulated from the metal strip in the existing processing line, or additionally installed In this case, the generation of stray current cannot be prevented, and the following problems have occurred.

(A) When a metal band is sheared by a shear installed in the processing line, sparks are generated between the shear and the metal band, and the metal band is damaged, shear blades are cut off, and the metal band is abnormally sheared. And so on.

(B) Sparks generated between the surface of the metal roll provided in the line and the metal band cause spatter to adhere to the roll surface, and the sputter causes indentation flaws in the metal band.

(C) Electric current flows through the bearing of the metal roll, causing seizing of the bearing.

(D) For the reason of the passing operation, when the operator thrusts the metal rod between the metal strip and the passing device, a spark is generated and the operator is burned.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION In order to solve the problems of the prior art, the present invention simply and automatically suppresses the generation of stray current in a series of processing lines having a device for continuously electrolyzing a metal strip, The object of the present invention is to prevent damage to various devices and devices in the metal strip and the processing line caused by the above, and to stably protect the metal strip and the processing line.

[Means for solving the problem]

The present inventors have found that in the path where the stray current flows outside the electrolytic treatment apparatus, damage caused by the stray current not only to the metal strip but also to the rewinding device and the winding device as well as to the metal rolls and shears for the passing plate is actually caused. As a result of investigating the position of the equipment that may occur or possibly occur in the metal strip closer to the electrolytic processing device than the equipment, the potential polarity at that location when the stray current is flowing is By constantly applying a voltage of the opposite potential polarity using an external power supply different from the electrolytic power supply of the electrolytic treatment device, we have investigated that the generation of stray current can be easily and dynamically suppressed. The present invention has been completed.

As the electrolytic treatment apparatus referred to in the present invention, there are a plating apparatus and a descaling apparatus, and the apparatus may be composed of only one tank or a plurality of tanks. Hereinafter, the present invention will be described in comparison with a case where the present invention is not applied, using a processing line having a two-tank type descaling electrolytic processing apparatus as an example. The present invention is similarly applied to the case of installation.

FIG. 1 is a schematic diagram of an example in which the apparatus of the present invention is applied to an electrolytic processing line, FIG. 2 is a simplified equivalent circuit diagram of FIG. 1, and FIG. 3 does not apply the present invention to FIG. FIG. 4 is an explanatory view of a path of a stray current when performing an electrolytic treatment, and FIG.
It is a simplified equivalent circuit diagram of the figure.

The processing line shown in FIG. 1 and FIG. 3 is a descaling line which has a two-tank type descaling electrolytic treatment device and shows only the main devices and equipment. It is like. The metal strip 19 unwound from the rewinding device 1 is driven by a metal roll 2 for threading and continuously travels, passes through the inlet-side electrolytic treatment device 5 and the exit-side electrolytic treatment device 6 sequentially, and again passes through the sheet-passing metal roll. Winding device 4 through metal roll 2
Continuously wound. The entrance-side electrolysis apparatus 5 and the exit-side electrolysis apparatus 6 are provided with a positive electrode 7 and a negative electrode 8 facing the surface of the metal strip 19, respectively. (It is a variable current type for electric power adjustment.) When the metal strip 19 passes through each of the electrolytic processing devices 5 and 6 in which the electrolytic solution has entered, the portions facing the respective electrodes 7 and 8 are respectively A circuit is formed by polarizing the negative electrode and the positive electrode, and an electrolytic current 12 indicated by a dashed line in the direction shown flows.Therefore, if attention is paid to a certain portion of the traveling metal strip 19, the cathodic electrolysis and the anodic electrolysis are sequentially performed. Under the action, the descaling process is performed, and it is wound by the winding device 4 while being cut by the shear 3 at an appropriate place.

In such an electrolytic treatment, the original electrolytic current 12 flows through the current path of (electrolytic power supply 9) → positive electrode 7 → metal strip 19 → negative electrode 8 → (electrolytic power supply 9) as described above. However, the processing line has a device that has a portion that is always in contact with the metal band 19, such as a metal roll 2 for passing plate, an unwinding device 1, and a winding device 4 on the entrance and exit sides of the electrolytic treatment device. And equipment having parts that may come into contact with the metal band 19 when necessary, such as the shears 3 and the like, are installed directly or on the ground by a frame or a gantry that supports them. Therefore, the stray current 13 having the electric resistance 9 as a base point and an end point as shown by a two-dot chain line in FIG.
The path is in a state where any number of paths can be formed in addition to the original current path, that is, the electrolytic current 12. Accordingly, when the potential difference between the positive electrode 7 and the negative electrode 8 is larger than a certain level, the stray current 13 in the current path direction shown in FIG. ) → Positive electrode 7 → Metal band
19 → metal roll 2 → frame, gantry, ground → metal roll 2 → metal strip 19 → cathode 8 → (electrolytic power supply 9), or in place of or in addition to metal roll 2, rewinding device 1 or It flows through the winding device 4. Also, when the shear 3 operates to shear the metal strip 19, the shear 3 can also be a path for the stray current 13. The path and the size of the stray current 13 are determined by the metal strip (metal type, steel type,
Differences in size, differences in electrolytic processing equipment and processing lines with the same, differences in processing lines in which various devices and equipment are connected, and differences between components and equipment and the entire processing line. It varies depending on the difference between grounding and insulation, electrolytic treatment conditions (such as sheet passing speed, electrolytic current density in the metal strip, concentration and temperature of the electrolytic treatment liquid, and temperature of the metal strip) and various operating conditions. I do. FIG. 4 shows a simplified equivalent circuit of such a stray current 13. The original current 20 (I) flowing out of the electrolytic power supply 9 and receiving the electric circuit resistance 14 (RL ₁ ) at a point A (corresponding to the upstream end of the positive electrode 7) has a metal band resistance 15 between the positive and negative polarizations. divided into (Rst) subjected electrolysis current 12 (I ₁₎ and the vagus path resistor 16 stray currents 13 which receives the (RA) (I _2), meet at point B (corresponding to the downstream end of the negative electrode 8) Then, it receives the electric circuit resistance 14 (RL ₂ ) again and returns to the electrolytic current 9. The magnitude of this stray current 13 (I ₂ ) is given by the potential difference between the input and output sides of the electrolytic treatment apparatus, that is, the potential difference between points A and B, as V ″. Becomes In the present invention, the potential difference V ″ between the points A and B approaches zero, that is, the potential difference V ″ is erased.

That is, one aspect of the present invention relates to an electrolytic treatment apparatus in which an indirect current is supplied from an electrolytic power source through an electrode arranged opposite to the metal strip to be passed along the length direction of the metal strip to be passed and a metal strip to be passed. A metal strip is continuously passed through a processing line in which a device or an apparatus having a part that is always in contact and / or a part that may come into contact is installed, and the metal strip on both sides of the entrance and exit of the electrolytic treatment apparatus and the above. When performing electrolysis while generating stray current that makes the device or device a part of the current path, the electrolysis device is more protected than the device or device that should protect the stray current on the upstream and downstream lines of the electrolysis device. The potential difference detection point of the metal band is set at a position close to, and the potential difference between the two detection points on the metal band and its potential polarity are continuously detected, and the potential difference is detected in the vicinity of one of the two detection points. Is detected at one of the detection points Suppresses the generation of stray current by reducing the potential difference between the two detection points on the metal band by constantly applying a voltage controlled to be substantially equal with the opposite potential polarity from an external power source different from the electrolytic power source. This is a method for suppressing stray current.

Another aspect of the present invention is an electrolytic processing apparatus in which an indirect current is supplied from an electrolytic power source via an electrode arranged along the length direction of a metal strip to be passed and an electrode disposed opposite to the metal strip, and a metal to be passed. A metal strip is continuously passed through a processing line in which a device or an apparatus having a part that is constantly in contact with the strip and / or a part that may be in contact is installed, and a metal strip on both sides of the entrance and exit of the electrolytic treatment apparatus. And a device that suppresses the generation of the stray current when performing the electrolytic treatment while generating the stray current in which the device or the device is a part of a current path, and (i) upstream and downstream of the line of the electrolytic treatment device And a contact for detecting a potential difference, which is installed so as to be always in contact with a potential difference detecting point of a metal strip which is set closer to the electrolytic processing apparatus than a device or an apparatus to be protected from stray current on the side. Potential between detection points Path potential difference detector comprising a stray path potential difference detection amplifier for continuously detecting the potential and the polarity of the potential; (ii) an external power supply that is different from the electrolytic power supply and can be controlled in voltage; (iii) the two potential differences (Iv) a potential difference detected by a detector having the stray path potential difference detection amplifier and a potential polarity detected by the detector having the stray path potential difference detection amplifier as an input signal; An external power supply voltage control amplifier that outputs a potential control signal to an external power supply to make these close to zero, ie, to erase the external power supply, and an external power supply having a polarity opposite to the potential difference detection point on the side where the power supply device is installed. And the other end of the external power supply is connected to the electrode of the electrolytic power supply of the electrolytic processing apparatus which has the same potential polarity as the other terminal and is closest to the power supply. It is stray current suppression apparatus according to claim being.

The principle of the present invention will be described with reference to a simplified equivalent circuit diagram of FIG. In the present invention, a circuit having an external power supply 10 is provided between a selected point C (corresponding to a position of a power supply device 18 described later) on the stray electric path and the electrolytic power supply 9. The circuit resistance 16 (RA) of the stray circuit in FIG. 4 is divided into a stray circuit resistance 16 '(RA') and a metal strip resistor 15 '(Rst') at point C in FIG. (RL ₃ ) is connected so as to apply a voltage V ′, which is opposite to the potential polarity of the external power supply 10 and the electrolytic power supply 9 at the point C, to the point C. If there is no circuit including the external power supply 10 added in the circuit of FIG. 2, the stray current 13 (I ₂ ) is almost the same as that of FIG. The current returns to the electrolytic power source 9 through the resistance 16 '(RA'), the point C, the metal strip resistance 15 '(Rst'), and the point B sequentially. However, when the external power supply 10 is operated and a voltage of the opposite potential is applied to the point C, the stray current suppressing current 21 (I ₃ ) flows in the direction of the arrow as shown in FIG. , The stray current 13 (I ₂ ) decreases accordingly. The reverse voltage V 'applied from the external power supply 10 to the point C of the metal strip 19 is controlled by a potential control signal output from the external power supply voltage control amplifier 11 so that the potential difference between the points A and C approaches zero. About, and if you make it zero, stray telegram
The size of 13 (I ₂ ) becomes smaller and smaller, and can be finally erased.

The device of the present invention furthermore specifically configures the above principle.

〔Example〕

The apparatus of the present invention will be described in detail with reference to an embodiment shown in FIG.

In setting potential difference detection points on the metal strip on both sides of the entrance and exit (same as upstream and downstream of the line) of the electrolytic treatment devices 5 and 6, protection from stray current 13 should be provided on the entrance or exit side Determine the actual conditions and forecasts of equipment and devices. When there are a plurality of such devices or devices, the devices and the devices including these devices are grasped as the stray current reduction necessary section. In the present embodiment, the devices to be protected from the stray current 13 are the metal roll 2 and the shear 3 device. Therefore, in this example, as shown in FIG. 1, the potential difference detection points of the metal strip 19 are set at positions closer to the electrolytic processing apparatus side than the metal roll 2 on both the upstream and downstream sides of the line. In the first position
As shown in the figure, the potential difference detecting contacts 17 and 17 are installed, and the stray path potential difference detecting amplifier 22 that detects and outputs the potential polarity as well as the potential difference between the two detection points according to a signal input therefrom is installed. . In this case, when there is no particular device or equipment to be protected from the stray current 13, the two detection points are set at the nearest positions on both sides of the entrance and exit of the electrolytic treatment devices 5 and 6, and the positions of these two detection points are set. Contact for detecting potential difference 17,1
7 may be installed. Then, a power supply device 18, such as a contact-type metal power supply roll, for example, is installed near one of the potential difference detection points, and therefore near one of the potential difference detection contacts 17, 17. Generally, when the mounting position of the power supply device 18 is installed close to the electrolytic processing devices 5 and 6, the section for suppressing the stray current can be lengthened, but the external power supply 10 for suppressing the stray current needs to have a large capacity. I do. Conversely, when the mounting position of the power supply device 18 is far away from the electrolytic processing devices 5 and 6, the external power supply 10 can have a small capacity, but the section for suppressing the stray current becomes short. It is preferable that the position is closer to the electrolytic processing apparatus and closer to the apparatus or apparatus than to the apparatus or apparatus that needs to reduce the passage of the stray current 13 as a whole. In addition, although it is not limited which of the upstream and downstream sides of the line is in the vicinity of the potential difference detecting contacts 17, it is preferable from the above viewpoint that the distance from the electrolytic processing apparatus is long. In this example, the potential difference detecting contact 17 on the downstream side of the line is selected. If the potential difference detection contact 17 on the upstream side of the line is selected,
The potential polarity and the like of the applied voltage are opposite to the potential polarity of the present example described later.

In addition, an electrolytic power supply voltage detector 23 for detecting the voltage of the electrolytic power supply 9, an external power supply 10, and an external power supply voltage control amplifier 11 are provided. This external power supply voltage control amplifier 11
It is preferable to use a proportional / integral type so as to eliminate the offset.A potential control signal which reduces and eliminates the potential difference detected and output by the stray circuit potential difference detection amplifier 22 and its potential polarity is supplied to the external power supply 10. Output. The reason why the electrolytic power supply voltage detected by the electrolytic power supply voltage detector 23 is input to the external power supply voltage control amplifier 11 is that the potential difference detected by the stray circuit potential difference detecting amplifier 22 is based on the electrolytic power supply voltage V This is because the reference voltage can be a stable reference voltage in order to prevent the control system from becoming abnormal instantaneously even if the potential difference detected due to the malfunction of the stray circuit potential difference detection amplifier 22 becomes unstable.

The above devices and devices are connected and connected as follows. The power supply device 18 is so controlled that the external power supply 10 applies an approximately equal amount of voltage with a polarity opposite to that of the potential difference detection point on the side where the power supply device is installed (therefore, in this example, downstream of the line). In this example, as shown in FIG. 1, the terminal is connected to the plus terminal (+ terminal) of the external power supply 10, and the other terminal of the external power supply 10, that is, the negative terminal (− terminal) is connected to the electrolytic power supply 9 of the electrolytic processing apparatuses 5 and 6.
Of the external power supply 10 is connected to the electrode having the same potential polarity as that of the other terminal of the external power supply 10, that is, the negative electrode which is closest to the power supply device 18 (in this example, one negative electrode for simplicity). . The stray path potential difference detection amplifier 22 is used to input the detection signal to the external power supply voltage control amplifier 11, and the electrolysis power supply voltage detector 23 extracts the detection signal (voltage) from the electrolysis power supply 9 and controls the external power supply voltage External power supply voltage control amplifier, connected so that it can be input to amplifier 11
The output (potential control signal) from 11 is connected and connected so that it can be input to the external power supply 10. Thus, the device of the present invention is configured as shown in FIG.

Next, the case where the method of the present invention is carried out using each of the above-described devices and apparatuses will be described together with their operations. First, the metal strip 19 in the range of allowable metal type, steel type, size expansion, etc. is subjected to electrolytic treatment by an electrolytic treatment apparatus in a processing line while continuously passing the metal strip 19 as usual. The potential difference between the contacts 17, 17 and its potential polarity are determined by the stray path potential difference detection amplifier 22.
, And is input to the external power supply voltage control amplifier 11, so that the voltage of the variable voltage type external power supply 10 is controlled so that these potential differences and their potential polarities are continuously reduced to zero or close to zero while being continuously detected. I do. As described above, the external power supply 10 applies a voltage to the power supply device 18 in a direction opposite to the potential polarity of the electrolytic current 12 from the electrolytic power supply 9 at the potential difference detection point (the same position as the contacts 17 and 17). Therefore, as described above, the potential difference between the contacts 17, 17 and the potential polarity thereof can be made zero or close to zero, that is, the potential difference can be eliminated. The method of the present invention capable of exhibiting such an erasing effect is automatically performed by the device of the present invention as described with reference to FIG.

The implementation of the method of the present invention makes it possible to make the potential difference between the potential difference detection points zero or close to zero, that is, the stray current via the metal strip 19 outside the potential difference detection point from the electrolytic processing apparatus in the stray current path. This means that the current 13 can be reduced to zero or close to zero, so that the stray current 13 flowing through the metal roll 2 or the shear 3 outside the potential difference detection point can be reduced to zero or close to zero and eliminated. . Further, even when the signal of the potential difference between the contacts 17, 17 does not enter the external power supply voltage control amplifier 11 for some reason, the voltage of the electrolytic power supply 9 is detected and input by the electrolytic power supply voltage detector 23. By doing so, it is possible to take countermeasures without causing abnormal operation immediately.

〔The invention's effect〕

As described in detail above, the present invention is provided with an electrolytic treatment apparatus having a large difference in the metal electrostatic potential on the entrance and exit sides of the electrolytic treatment apparatus. In the continuous treatment of metal strips with equipment that does not have a stray current, a voltage opposite to the polarity of the potential when the stray current is flowing in the metal strip closer to the electrolytic treatment device than the device or equipment to be protected from stray current is externally applied. The configuration described below in which the voltage is applied by the power supply has the following effects.

(I) The generation of stray current in a series of processing lines can be easily and automatically suppressed. As a result, the following effects can be obtained.

(Ii) When the metal band is sheared by the shear, sparks generated between the shear and the metal band are prevented, and the metal band itself is damaged,
Prevents chipping of shears and abnormal shearing of metal bands.

(Iii) Small sparks generated between the surface of the metal roll and the metal strip are eliminated, and spatters attached to the roll do not scratch the metal strip surface.

(Iv) The electric current flowing through the metal roll bearing is eliminated, and seizure of the bearing can be prevented.

(V) Even if the metal rod is inserted between the metal strip and the passing device, no spark is generated and the human body is not affected.

(Vi) In this way, not only the metal strip passing continuously, but also the processing line composed of various devices and equipment other than the electrolytic processing equipment can be protected and stably maintained, and the quality and step of the metal strip can be maintained. It is very effective in improving the clearance, improving the efficiency and productivity of the processing line, and reducing maintenance costs.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example in which the apparatus of the present invention is applied to an electrolytic processing line, FIG. 2 is a simplified equivalent circuit diagram of FIG. 1,
FIG. 3 is an explanatory diagram of a path of a stray current when performing electrolytic treatment without applying the present invention in FIG. 1, and FIG. 4 is a simplified equivalent circuit diagram of FIG. In the drawings, 1 ... Rewinding device 2 ... Metal roll for passing plate 3 ... Shear 4 ... Rewinding device 5 ... Incoming electrolytic treatment device 6 ... Outgoing electrolytic treatment device 7 ... Positive electrode 8 ... … Negative electrode 9… Electrolytic power supply 10… External power supply 11… Amplifier for external power supply voltage control 12… Electrolytic current 13… Stray current 14,14 ′… Electrical circuit resistance 15,15 ′… Metal strip resistance 16 , 16 '... Stray current path resistance 17 ... Contact for detecting potential difference 18 ... Feeding device 19 ... Metal band 20 ... Original current 21 ... Stray current suppressing current 22 ... Amplifier for detecting potential difference 23 ... electrolyte supply voltage detector _{I 1, I 2, I 3} ...... current RA, RA '...... stray current resistance _{RL 1, RL 2, RL 3} ...... path resistance RSt, RSt' ...... metal strip resistor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C25D 21/00-21/12 C25D 7/06 C25F 7/00

Claims (2)

(57) [Claims] 1. An electrolytic power source (9) passing through an electrode disposed along the length of a metal strip (19) to be passed through and facing the metal strip (19).
A metal strip (19) is installed in a processing line in which an apparatus or an apparatus having a part and / or a part that is always in contact with an electrolytic treatment apparatus and a metal strip (19) that is indirectly supplied with electricity is installed. ) Is passed continuously, and the metal strip (19) on both the entrance and exit of the electrolytic treatment device and the stray current (13) that makes the above devices and equipment a part of the current path are subjected to electrolytic treatment. The potential difference detection point of the metal strip (19) is set at a position closer to the electrolytic treatment device than the device or equipment to be protected from stray current (13) on the upstream and downstream sides of the electrolytic treatment device, and The potential difference between the two detection points on the band (19) and its potential polarity are continuously detected, and the potential polarity near the one of the two detection points is opposite to that detected at the one detection point. Voltage from an external power supply (10) different from the electrolytic power supply (9) A stray current suppressing method, wherein a stray current (13) is suppressed by reducing the potential difference between the two detection points of the metal strip (19). 2. An electrolytic power supply (9) through electrodes arranged along the length direction of a metal strip (19) to be passed through and facing the metal strip (19).
A metal strip (19) is installed in a processing line in which an apparatus or an apparatus having a part and / or a part that is always in contact with an electrolytic treatment apparatus and a metal strip (19) that is indirectly supplied with electricity is installed. ) Is passed continuously, and the electrolytic treatment is carried out with the generation of the metal strips (19) on both the entrance and exit of the electrolytic treatment equipment and the stray current (13) that makes the above equipment and equipment part of the current path. And (i) an electrolytic treatment device rather than a device or device that should protect the stray current (13) upstream and downstream of the line of the electrolytic treatment device. (17), (17) for detecting the potential difference, which are always set to be able to always contact the potential difference detection points of the metal strip (19) set at a position close to, and the potential difference between the two detection points and its potential Stray path potential difference that detects polarity continuously (Ii) an external power supply (10) that is different from the electrolytic power supply (9) and can be controlled in voltage; and (iii) any of the two potential difference detection points. (Iv) a power supply device (18) installed near one of the metal strips (19) so as to be in contact with the metal strip (19); and (iv) an amplifier (22) for detecting the difference between the electrolytic power supply voltage detected by the electrolytic power supply voltage detector (23) and the stray circuit potential. ) Is used as an input signal, and a potential control signal for eliminating the potential difference detected by the stray path potential difference detection amplifier (22) and its potential polarity is supplied to an external power supply (10). An external power supply voltage control amplifier (11) for outputting, and a terminal of the external power supply (10) having a polarity opposite to that of the potential difference detection point on the side where the power supply device (18) is installed, and the power supply device (18). Is connected, and the other terminal of the external power supply (10) is electrolytically treated. Stray current suppression apparatus characterized by being connected to the electrode closest to thickness feeding device (18) at the same potential polarity as the other terminal of the electrolytic power supply (9) of the location (5,6).