JP5904338B2 - Clogging prevention method and clogging prevention device for wiping nozzle - Google Patents

Description

  The present invention relates to a method and apparatus for preventing clogging of a wiping nozzle in a continuous hot dip galvanizing line.

  In a continuous hot dip galvanizing line, the steel plate is heat treated to give the specified mechanical properties, and the steel plate surface is reduced, cleaned, activated, and then immersed in a hot dip galvanized bath. The hot dip galvanized steel sheet is then attached to the galvanized steel sheet, and then pulled up by reversing the direction of travel with a sink roll in the bath. The galvanized steel sheet and the galvannealed steel sheet are collectively referred to as “hot dip galvanized steel sheet”).

In the hot dipping process, it is necessary to squeeze out excess zinc adhering to the steel sheet surface. As a method of squeezing out zinc, a roll squeezing method in which zinc on the surface of the steel sheet is squeezed out with two grooved rolls installed on the bath surface, and as shown in FIG. 1, water vapor, nitrogen gas, combustion from the slit nozzle A gas throttling method in which a throttling gas such as waste gas is blown at a high pressure of 0.2 to ² kgf / cm ² and throttling with a gas jet knife is common, and the latter is the mainstream at present.

  By the way, in the case of the gas throttling method, since high pressure gas is blown on the front and back of the steel sheet, the high-pressure gas ejected from one of the wiping nozzles blows away the molten zinc adhering to the steel sheet surface, particularly the steel sheet end, and faces it It may adhere to the slit portion of the wiping nozzle. When this adhesion occurs, the slit for ejecting the high-pressure gas becomes narrow or clogged, and the amount of the ejected gas decreases, making it impossible to squeeze out the zinc adhering to the steel sheet surface to a predetermined amount. Unevenness occurs or the clogged portion becomes streaky, causing a poor surface appearance.

  Therefore, conventionally, when nozzle clogging due to adhered zinc occurs, the worker has removed the adhered zinc using a special jig. However, since this method requires time and labor, it has been a factor that causes a significant decrease in yield. Moreover, since the said removal operation | work becomes work on a molten zinc bathtub, there existed a problem on safety.

Therefore, as a technique for solving the above-mentioned problem, for example, Patent Document 1 discloses a zinc cleaning plate which is attached to a wiping nozzle by moving a plate-like cleaning plate provided to be freely movable back and forth by remote operation from the outside. An apparatus is disclosed for removing.
Further, in Patent Document 2, a plate-like baffle plate (edge plate) is brought close to the end surface of the steel plate to suppress the gas flow in the outer direction of the wiping gas, thereby excessively adding zinc to the edge portion of the steel plate. An edge portion overcoat prevention device for preventing adhesion is disclosed. This technique is also effective in preventing nozzle clogging because it has the effect of preventing the turbulence of the air flow at the end of the steel plate and preventing the scattering of molten zinc.

Japanese Utility Model Publication No. 03-22059 Japanese Utility Model Publication No. 03-22060

However, the technique disclosed in Patent Document 1 is effective as a countermeasure after occurrence of clogging, but does not prevent clogging itself. Further, when the nozzle is clogged, the part manufactured from the clogging to the completion of the maintenance becomes defective and deteriorates the yield, so that the fundamental problem is not solved.
In addition, by applying this technique to the technique of Patent Document 2, nozzle clogging is prevented, and a great effect can be obtained in reducing product defects due to clogging. However, according to investigations by the inventors, it has become clear that clogging of the nozzles has not been completely prevented even by the installation of the baffle plate, and further improvement is required.

  The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to propose a clogging prevention method capable of reliably preventing nozzle clogging due to zinc adhesion to the wiping nozzle, It is to provide such a device.

  The inventors have made extensive studies on a method for solving the above problems. As a result, clogging of the wiping nozzle, which is also caused by the installation of the baffle plate, cannot be left with the baffle plate installed when the welding point passes through the wiping nozzle, particularly when the plate width is changed. Therefore, it was found that there was a cause in temporarily evacuating the baffle plate. Therefore, in order to prevent the above clogging, it was considered effective to install a baffle plate even when passing through the welding point, and a movable baffle plate was examined. It is difficult to move by. As a result of various studies, the present inventors have found that it is effective to insert a plate that shields high-pressure gas between the wiping nozzle and the steel plate in place of the baffle plate.

  That is, the present invention is a method for preventing clogging of a wiping nozzle in a continuous hot dip galvanizing line, and when a welding point of a preceding steel plate and a succeeding steel plate passes through the wiping nozzle portion, along the traveling steel plate end portion. A method for preventing clogging of a wiping nozzle, wherein a clogging prevention plate is inserted between a steel plate and a wiping nozzle at the same time or just before the baffle plate disposed in proximity is retracted.

  Further, the present invention is an apparatus for preventing clogging of a wiping nozzle in a continuous hot dip galvanizing line, which is arranged close to the traveling steel plate end portion and is capable of moving back and forth in the plate width direction, and a preceding steel plate, A clogging prevention plate is inserted between the steel plate and the wiping nozzle at the same time as or immediately before retraction of the baffle plate when the welding point of the subsequent steel plate passes through the wiping nozzle portion. This is a clogging prevention device.

  According to the present invention, when the welding point passes through the wiping nozzle portion, the clogging prevention plate is inserted between the steel plate and the wiping nozzle at the same time as or immediately before the baffle plate is retracted, and the molten zinc at the steel plate width end portion is inserted. Therefore, it is possible to effectively prevent clogging of the wiping nozzle that occurs when passing through the welding point, and the deterioration of the surface quality and the yield of the product steel plate due to the clogging. Furthermore, according to the present invention, the clogging of the wiping nozzle can be prevented, so that the work of removing zinc adhering to the nozzle can be greatly reduced, and safety is improved. , Greatly contribute to productivity improvement.

It is a figure explaining the control method of the zinc adhesion amount by a gas throttling method. It is a figure which shows the width direction position of the wiping nozzle with which clogging generate | occur | produced. It is a graph which shows the investigation result of the steel plate position at the time of CGL passing, where the appearance defect resulting from clogging of the wiping nozzle starts to occur. It is a figure explaining the position of the baffle plate in the normal time of the overcoat prevention apparatus of a prior art. It is a figure explaining the position of the baffle plate at the time of the welding point passage of the prior art overcoat prevention device. It is a figure explaining the position of the baffle plate in the normal time of the clogging prevention apparatus of this invention, and a clogging prevention board. It is a figure explaining the position of the baffle plate and clogging prevention plate at the time of welding point passage of the clogging prevention device of the present invention.

In order to clarify the cause of clogging of the wiping nozzle, the inventors have determined the position in the width direction of the wiping nozzle where clogging has occurred and the hot dip galvanizing line (CGL) where appearance defects due to clogging start to occur. The longitudinal position in the steel plate (coil) was investigated.
FIG. 2 shows the result of investigation of the position in the width direction of the wiping nozzle where clogging has occurred. From this figure, the maximum width and the minimum width of the material to be plated (steel plate), that is, the end of the steel plate It can be seen that clogging has occurred in the range through which. From this, it was guessed that the zinc adhering to the wiping nozzle was blown off by the high-pressure gas jetted from the nozzle in excess molten zinc adhering to the end of the steel plate.

Moreover, FIG. 3 is a result of classifying the positions where appearance defects due to nozzle clogging have started to occur according to the positions in the steel plate (coil) when plating is performed on a continuous hot dip galvanizing line (CGL). Is shown. From this figure, the position where nozzle clogging begins to occur is not starting from the middle and end portions of the steel sheet during CGL passing, but starting from the top of the steel sheet, that is, in CGL, the steel sheet is continuously In order to perform the plating process, the preceding steel plate and the subsequent steel plate are welded and passed, and it can be seen that the welding point occurs immediately after passing through the wiping nozzle portion.

  In the technique of Patent Document 2 described above, when the material to be plated passes through the wiping nozzle portion, as shown in FIG. Excessive adhesion of zinc to the surface is suppressed. Here, reference numeral 1 in the figure denotes a steel plate, and 2 denotes a wiping nozzle. The high-pressure gas 3 is blown onto the steel plate surface from both sides with the steel plate interposed therebetween to control the basis weight of zinc. Reference numeral 4 denotes a baffle plate. In a stationary part having a constant plate width, the baffle plate is arranged at a distance of several millimeters along the end of the steel plate, and follows the plate width variation and meandering of the steel plate. The structure advances and retreats in the width direction and always keeps the separation distance constant. However, in order to avoid contact between the baffle plate and the steel plate when the welding point 5, in particular, the welding point 5 that shifts from a narrow width to a wide width passes through the wiping nozzle portion, as shown in FIG. The plate is temporarily retracted in the width direction of the steel plate.

From these facts, the nozzle clogging that the present invention is trying to solve is that the baffle plate is temporarily retracted when the welding point passes through the wiping nozzle portion, so that the high pressure gas injected from one nozzle causes the clogging. It was inferred that the cause was that the molten zinc adhering excessively to the end of the steel plate was blown off and adhered to the slit portion of the opposing nozzle.
Therefore, in order to prevent clogging of the nozzle, when the welding point passes through the wiping nozzle portion, another shielding plate (clogging prevention plate) is used instead of the baffle plate temporarily retracted. It is considered to be inserted between.

  That is, according to the method for preventing clogging of the wiping nozzle of the present invention, when the welding point of the preceding steel plate and the succeeding steel plate passes through the wiping nozzle portion, the baffle plate disposed in close proximity along the traveling steel plate end is retracted. At the same time or just before retraction, a clogging prevention plate is inserted between the steel plate and the wiping nozzle. Further, the clogging prevention device for a wiping nozzle according to the present invention includes a baffle plate that is disposed close to the traveling steel plate end portion and can be advanced and retracted in the plate width direction, and a welding point between the preceding steel plate and the subsequent steel plate is the wiping nozzle portion. And a clogging prevention plate inserted between the steel plate and the wiping nozzle at the same time as the baffle plate is retracted or just before the retraction.

  FIG. 6 is a conceptual diagram of the clogging prevention device of the present invention. 4, 1 is a steel plate, 2 is a wiping nozzle, 3 is a high-pressure gas ejected from the wiping nozzle, and 4 is a baffle plate disposed close to the end of the steel plate. The clogging prevention device is characterized in that a clogging prevention plate 6 is further provided in addition to the above.

The clogging prevention plate 6 is disposed on the outer side in the plate width direction with respect to the baffle plate 4 as shown in FIG.
On the other hand, when the welding point 5 passes through the wiping nozzle part, particularly when the welding point 5 whose plate width changes from narrow to wide as shown in FIG. 7, the baffle is avoided in order to avoid contact with the steel plate. The plate 4 is temporarily retracted. However, as described above, the high-pressure gas ejected from the nozzle causes the zinc at the end of the steel sheet to scatter and cause nozzle clogging. Therefore, the clogging prevention plate 6 instead of the baffle plate 4 is inserted between the wiping nozzle 2 and the steel plate 1 to prevent zinc from being scattered from the end of the steel plate.

  The timing for inserting the clogging prevention plate may be simultaneous with the retraction of the baffle plate, but from the viewpoint of reliably preventing zinc scattering, the insertion should be completed immediately before the baffle plate starts to retreat. Is preferred. Moreover, after a welding point passes the wiping nozzle part, while making a baffle plate adjoin to a steel plate edge part rapidly, a clogging prevention board is retracted. This timing is preferably after completion of the proximity of the baffle plate to the steel plate end from the viewpoint of reliably preventing the molten zinc from scattering.

  In addition, although the said clogging prevention board is installed in the at least one surface side of a steel plate, it is preferable to install in both surfaces of a steel plate. Moreover, the said clogging prevention board may be comprised from two sheets, and the thing which bent one board in the shape of a U-shape and straddled on both surfaces of the steel plate may be sufficient. The clogging prevention plate may be installed at least near the edge where the steel plate does not pass through the width of the wiping nozzle, but since the welding point is not used as a product, the entire width of the wiping nozzle May be installed. The direction in which the clogging prevention plate is inserted is not particularly limited, and the clogging prevention plate may be inserted from an outer portion of the width of the steel plate or may be inserted from the upper part of the wiping nozzle.

  Moreover, the said clogging prevention board should just be installed in the position which does not contact a steel plate surface between a steel plate surface and a wiping nozzle, but it is preferable to make it 3 mm or more away from a steel plate. The installation position from the wiping nozzle is not particularly limited, and may be a system that moves while being in contact with the nozzle surface of the wiping nozzle.

  The mechanism for advancing and retreating the clogging prevention plate is not particularly limited, but the same mechanism as the baffle plate advancing and retreating mechanism can be used, and the clogging prevention plate is interlocked with the advancing and retreating of the baffle plate when passing through the welding point. You can move forward and backward.

  When the conventional baffle plate shown in FIGS. 4 and 5 is installed in the continuous hot dip galvanizing line (comparative example), in addition to the baffle plate, the clogging prevention plate shown in FIGS. 6 and 7 In the former, which is a comparative example, the ratio of the number of coils to the total number of through-plate coils was defined as the clogging occurrence rate. While the occurrence rate of clogging was 3%, the occurrence rate of clogging of the latter, which is an example of the invention, was 1%, which was significantly reduced.

  In the above description, hot-dip galvanized steel sheets (including alloyed hot-dip galvanized steel sheets) are targeted, but the technology of the present invention is not limited to the hot-dip galvanized steel sheets, and other metals (alloys) It can also be applied to hot-dip plating.

1: Steel plate 2: Wiping nozzle 3: Gas for drawing 4: Baffle plate (edge plate)
5: Welding point 6: Clogging prevention plate

Claims (2)

A method for preventing clogging of a wiping nozzle in a continuous hot dip galvanizing line,
When the welding point of the preceding steel plate and the following steel plate passes through the wiping nozzle, the baffle plate disposed close to the traveling steel plate end is retracted at the same time or immediately before the retraction of the steel plate and the wiping nozzle. A method for preventing clogging of a wiping nozzle, wherein a clogging prevention plate is inserted between the wiping nozzles. A device for preventing clogging of a wiping nozzle in a continuous hot dip galvanizing line,
A baffle plate that can be moved back and forth in the plate width direction, which is arranged close to the traveling steel plate end,
When the welding point of the preceding steel plate and the following steel plate passes through the wiping nozzle portion, it has a clogging prevention plate inserted between the steel plate and the wiping nozzle at the same time or just before the baffle plate is retracted. A clogging prevention device characterized by that.

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