WO2018079087A1

WO2018079087A1 - Gas wiping device and method for manufacturing molten metal plated steel strip

Info

Publication number: WO2018079087A1
Application number: PCT/JP2017/032136
Authority: WO
Inventors: 宗司吉本; 高橋　秀行; 優寺崎
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2016-10-24
Filing date: 2017-09-06
Publication date: 2018-05-03
Also published as: JP6610500B2; JP2018070904A

Abstract

The present invention provides a gas wiping device which can quickly remove molten metal splash adhered to a slit. This gas wiping device 20 is provided with a cleaning jig 40 having a tip plate 44 having a size that allows the tip plate 44 to be inserted into a slit 33 of a wiping nozzle 30. In addition, a displacement sensor 80 positioned adjacent to the slit 33 detects the presence and position of scattered molten metal in the slit. On the basis of positional information which pertains to the scattered molten metal and is output from the displacement sensor 80, a control unit 70 activates a driving mechanism to move the cleaning jig 40. Specifically, the tip plate 44 is inserted into the slit and moved, in the slit, to the position of scattered molten metal P along the plate width direction X of a steel strip, and the scattered molten metal P is thereby scraped and removed by means of the tip plate 44.

Description

Gas wiping apparatus and manufacturing method of hot-dip metal-plated steel strip

The present invention relates to a gas wiping device that adjusts the amount of molten metal deposited on the surface of the steel strip by blowing gas onto the steel strip pulled up from the molten metal bath, and a molten metal-plated steel strip using the gas wiping device. It relates to a manufacturing method.

Hot-dip galvanized steel sheet, a type of hot-dip metal-plated steel sheet, is widely used in fields such as building materials, automobiles, and home appliances. And in these uses, it is requested | required with respect to the hot dip galvanized steel plate that it is excellent in an external appearance. Here, since the appearance after coating is strongly influenced by surface defects such as uneven plating film thickness, wrinkles, and adhesion of foreign matter, it is important that the hot dip galvanized steel sheet has no surface defects.

The molten metal plated steel strip is generally manufactured by a continuous molten metal plating line as shown in FIG. That is, the steel strip S annealed in a continuous annealing furnace in a reducing atmosphere passes through the snout 10 and is continuously introduced into the molten metal bath 14 in the plating tank 12. Thereafter, the steel strip S is pulled up above the molten metal bath 14 via the sink roll 16 and the support roll 18 in the molten metal bath 14, adjusted to a predetermined plating thickness by a pair of wiping nozzles 30, and then cooled. To the subsequent process. The pair of wiping nozzles 30 are disposed above the plating tank 12 so as to face each other with the steel strip S interposed therebetween, and the gas injection port is constituted by a slit 33 extending in the plate width direction of the steel strip S. The gas sprayed from the slit 33 is sprayed on the surface of the steel strip S. As a result, excess molten metal is scraped off, the amount of plating adhesion on the steel strip surface is adjusted, and the melt attached to the steel strip surface The metal is made uniform in the plate width direction and the plate longitudinal direction.

In such a wiping nozzle 30, when a molten metal droplet P (hereinafter referred to as “splash”) scattered by gas injection adheres in the slit 33, the adhering splash P blocks the gas, so that the plate width direction It becomes impossible to inject gas uniformly. As a result, a surface defect with uneven film thickness occurs at the position of the steel strip surface corresponding to the position where the splash P adheres in the slit 33. Therefore, in order to improve the quality of the molten metal plated steel strip, it is necessary to quickly remove the splash P adhering to the slit 33.

When this removal operation is performed manually, there is a method in which, for example, an elongated metal plate cleaning jig is inserted into the slit 33 and moved in the plate width direction. However, all the steel strips passed through during work become scrap, and this method reduces the yield because of the long work time. Moreover, since it is the operation | work performed in the vicinity of the very high temperature molten metal bath 14, it is unpreferable from a viewpoint of safety.

Therefore, in Patent Document 1, a laser beam is irradiated into the slit from one end of the slit with a small output, and the adhesion of the splash in the slit is detected based on the change in the amount of light detected by the light detection unit provided at the other end. In addition, a technique is described in which when the adhesion of splash is detected, the output of the laser beam is increased and the splash is melted and removed by the laser beam.

Also, Patent Document 2 describes the following technology. The plating thickness is measured by a pair of distance sensors that are arranged opposite to each other across the steel strip S downstream of the pair of wiping nozzles in the sheet passing direction. If this is not stable, it is detected that splash has adhered to the slit. To do. The wiping nozzle is provided with a clogging removal jig having a tip plate that can be inserted into the slit. When splash adheres to the slit, the tip plate is moved from one end to the other end in the plate width direction of the steel strip within the slit, and the splash is scraped off by the tip plate.

Japanese Patent Laid-Open No. 5-125517 JP 2013-181196 A

However, the method described in Patent Document 1 has a problem in that the nozzle portion that forms the slit is heated by the laser light for melting the splash, so that the nozzle portion expands and deforms. Further, it has been found that the nozzle portion forming the slit and the splash cause an alloying reaction, and the splash cannot be removed.

Further, in the method described in Patent Document 2, even if it is possible to determine whether or not the splash is attached in the slit by the distance sensor, it is not known where the splash is attached in the slit. For this reason, it is necessary to move the tip plate of the clogging removal jig from the one end of the slit to the other end in the full width, and when it cannot be removed by one operation, it is necessary to repeat the series of operations. Therefore, there are problems that the working time is long and the yield is lowered.

Therefore, in view of the above problems, an object of the present invention is to provide a gas wiping apparatus that can quickly remove molten metal splash adhering to a slit and a method for producing a molten metal plated steel strip.

When the present inventors diligently studied to solve the above problem, the displacement sensor is installed in the vicinity of the slit of the wiping nozzle, and the inside of the slit is constantly monitored by the displacement sensor, so that the splash adheres to the slit. In addition, the idea was that it was possible to instantaneously output the data indicating the adhesion and the position of the adhesion as data. Based on this data, the tip plate of the clogging removal jig is moved to the attachment position to scrape and remove the splash. Thus, it has been found that the splash can be automatically and efficiently removed quickly without moving the tip plate from one end to the other end of the slit in the full width.

The gist configuration of the present invention completed based on the above findings is as follows.
(1) A gas wiping apparatus that adjusts the amount of molten metal deposited on the surface of the steel strip by blowing gas to the steel strip pulled up from the molten metal bath,
A wiping nozzle that constitutes the gas injection port and has a slit at the tip that extends in the width direction of the steel strip;
A cleaning jig that includes a tip plate positioned outside the slit and sized to be inserted into the slit;
A drive mechanism for moving the cleaning jig;
A control unit for controlling the operation of the drive mechanism;
A displacement sensor that is located in the vicinity of the slit, detects the presence or absence of scattered molten metal in the slit, and the position of the scattered molten metal in the plate width direction of the steel strip;
And the control unit operates the drive mechanism based on the position information of the scattered molten metal output from the displacement sensor, inserts the tip plate into the slit, and further passes through the slit. The gas wiping apparatus characterized by scraping and removing the scattered molten metal adhering to the inside of the slit by the tip plate by moving to the position of the scattered molten metal along the plate width direction of the steel strip.

(2) The gas wiping apparatus according to (1), wherein the control unit causes the tip plate to reciprocate a predetermined amount of movement in the plate width direction around the position of the scattered molten metal.

(3) The gas wiping apparatus according to (1) or (2), wherein the displacement sensor is a non-contact optical displacement sensor.

(4) The drive mechanism moves the tip plate in the plate thickness direction and / or plate length direction in the slit in addition to the plate width direction. The gas wiping apparatus according to item.

(5) The gas wiping device according to any one of (1) to (4), wherein the drive mechanism includes an electric motor.

(6) The displacement sensor acquires two-dimensional or three-dimensional position information including the position in the plate thickness direction and / or the plate length direction in addition to the position in the plate width direction with respect to the position information of the scattered molten metal. The gas wiping device according to any one of (1) to (5) above.

(7) The tip plate has a shape that becomes wider toward the back of the slit, and an angle θ formed by both ends of the tip plate with respect to the thickness direction of the steel strip is 10 to 60 degrees. The gas wiping device according to any one of 1) to (6).

(8) A steel strip is continuously immersed in a molten metal bath,
A gas is blown onto the steel strip from the pair of gas wiping devices according to any one of the above (1) to (7), and the steel strip is disposed across the steel strip pulled up from the molten metal bath. Adjust the amount of molten metal on both sides of the
A method for producing a molten metal-plated steel strip that continuously produces a molten metal-plated steel strip.

According to the gas wiping apparatus of the present invention and the method for producing a molten metal plated steel strip, the molten metal splash adhering to the slit can be quickly removed.

It is a schematic diagram which shows the structure of the continuous molten metal plating equipment 100 used by one Embodiment of this invention. 1 is a schematic perspective view of a gas wiping device 20 according to a first embodiment of the present invention. 3 is a schematic cross-sectional view of a wiping nozzle 30 in the gas wiping apparatus 20 perpendicular to a steel strip and a bath surface. FIG. 3 is a schematic side view of a cleaning jig 40 in the gas wiping device 20. FIG. It is a figure which shows an example of the shape of the front end plate 44 of a cleaning jig. It is a model side view of the gas wiping apparatus 20 by the 2nd Embodiment of this invention. It is a model top view of the gas wiping apparatus 20 shown in FIG. It is a model front view of the gas wiping apparatus 20 shown in FIG. It is a graph which shows the relationship between the angle (theta) which the both ends of a front-end | tip plate make with respect to a plate | board thickness direction, the average working time of splash removal, and a steel strip yield. It is a schematic diagram which shows the structure of the conventional continuous molten metal plating equipment.

(First embodiment)
With reference to FIGS. 1 to 5, a gas wiping apparatus 20 according to a first embodiment of the present invention and a method for producing a hot-dip metal-plated steel strip using the gas wiping apparatus 20 will be described.

First, referring to FIG. 1, a continuous molten metal plating facility 100 used in an embodiment of the present invention includes a snout 10, a plating tank 12 that stores molten metal, a sink roll 16, and a support roll 18. . The snout 10 is a member having a rectangular cross section perpendicular to the traveling direction of the steel strip, which defines a space through which the steel strip S passes, and its tip is immersed in a molten metal bath 14 formed in the plating tank 12. Yes. In one embodiment, the steel strip S annealed in a continuous annealing furnace in a reducing atmosphere passes through the snout 10 and is continuously introduced into the molten metal bath 14 in the plating tank 12. Thereafter, the steel strip S is pulled up above the molten metal bath 14 via the sink roll 16 and the support roll 18 in the molten metal bath 14, adjusted to a predetermined plating thickness by the pair of gas wiping apparatuses 20, and then cooled. Then, it is led to the subsequent process.

In the method for manufacturing a molten metal-plated steel strip according to the present embodiment, a pair of gas wiping apparatuses 20 are arranged so that the steel strip S is continuously immersed in the molten metal bath 14 and the steel strip S is pulled up from the molten metal bath 14. From this, a gas is blown onto the steel strip S to adjust the amount of adhesion of the molten metal on both sides of the steel strip S to continuously produce a molten metal-plated steel strip.

Referring to FIG. 2 in addition to FIG. 1, the pair of gas wiping devices 20 are disposed above the plating tank 12 so as to face each other with the steel strip S interposed therebetween. The gas wiping device 20 blows gas toward the steel strip S from the injection port 33 (slit) extending in the plate width direction X of the steel strip at the tip thereof. Gas is sprayed from one gas wiping device 20 toward one surface of the steel strip, and gas is sprayed from the other gas wiping device 20 toward the other surface of the steel strip. Thereby, the excess molten metal is scraped off on both surfaces of the steel strip S, the amount of plating adhesion is adjusted, and the plate width direction X and the plate length direction Z are made uniform. The gas wiping device 20 is generally configured to be longer than the steel strip width in order to cope with various steel strip widths and to correspond to positional deviation in the width direction when the steel strip is pulled up, and from the end in the width direction of the steel strip. It extends to the outside.

In the present embodiment, the gas wiping device 20 includes a wiping nozzle 30, a cleaning jig 40, a drive mechanism 50, a control unit 70, and a displacement sensor 80. Hereinafter, each element will be described.

(Wiping nozzle 30)
Referring to FIG. 3, the wiping nozzle 30 includes an upper nozzle member 31 and a lower nozzle member 32. By aligning the upper nozzle member 31 and the lower nozzle member 32 in the vertical direction, a slit 33 is defined at the tip of the wiping nozzle 30, and a hollow portion 34 communicating with the slit 33 is defined. That is, the tip portions of the upper and

lower nozzle members

31 and 32 have planes facing each other in parallel, and the space between these planes becomes the slit 33. The slit 33 constitutes a gas injection port and extends in the plate width direction X.

The vertical cross-sectional shape of the wiping nozzle 30 is a tapered shape that tapers toward the tip as shown in FIG. The thickness of the tip portions of the upper and

lower nozzle members

31 and 32 may be about 1 to 3 mm. The slit dimensions are not particularly limited, but the slit length L1 (see FIG. 2) is set with a margin according to the width of the steel strip, and can be, for example, about 1500 to 2500 mm. The slit depth L2 (see FIG. 3) can be about 10 to 30 mm, and the slit width L3 (see FIG. 3) can be about 0.5 to 3.0 mm. The upper and

lower nozzle members

31 and 32 are connected to a gas supply pipe 36 on the base end side, and the gas supply pipe 36 and the hollow portion 34 are divided by the base ends of the upper and

lower nozzle members

31 and 32. 35 to communicate. A gas supplied from a gas supply mechanism (not shown) is sprayed from the slit 33 through the gas supply pipe 36, the gas supply path 35, and the hollow portion 34, and blown onto the surface of the steel strip S.

The material of the wiping nozzle 30 is not particularly limited, but it is preferable to use a material coated with a material such as WC, Al ₂ O ₃ , or ZrO ₂ that has no affinity for molten metal such as molten zinc. By doing so, the formation of an alloy layer between the molten metal and the wiping nozzle 30 is suppressed, and the splash adhering to the slit 33 can be easily removed.

(Cleaning jig 40)
Referring to FIG. 4 in addition to FIG. 2, the cleaning jig 40 includes a connection part 41, a base part 42, a bent part 43, and a tip part (tip plate) 44. The tip plate 44 is inserted into the slit 33 to physically scrape and remove the attached splash.

The connecting portion 41 is a portion that connects the cleaning jig 40 to a drive mechanism 50 described later, and is a plate-like member that is positioned along the flat surface of the upper nozzle member 31 in the present embodiment. However, the connection part 41 is suitably designed according to the structure of the drive mechanism 50, and is not limited to a plate-shaped member like this embodiment.

The base portion 42 is a member extending from the connection portion 41, and is a plate-like member along the inclined surface of the upper nozzle member 31 in the present embodiment. The bent portion 43 is a portion that connects the base portion 42 and the tip plate 44. In this way, the cleaning jig 40 has a shape that matches the wiping nozzle 30 so as not to interfere with the wiping nozzle 30 when moved to remove the splash.

The tip plate 44 has a shape matched to the slit 33 so that the inside of the slit 33 can be moved. The dimension of the tip plate 44 is not particularly limited as long as it can be inserted into the slit 33, but the thickness is preferably 0.1 mm or more smaller than the thickness of the slit 33. By ensuring a thickness difference of 0.1 mm or more between the slit 33 and the tip plate 44, when the tip plate 44 moves in the plate width direction X within the slit, the splash is reliably removed without being caught in the slit. It can be carried out. The dimensions of the tip plate 44 may be, for example, a thickness of about 0.5 to 3.0 mm, a width of about 10 to 60 mm, and a length (length in the depth direction of the slit) of about 10 to 30 mm.

The shape of the tip plate 44 can be rectangular as shown in FIG. As another embodiment, as shown in FIG. 5, the end plate 44 has both ends inclined with respect to the thickness direction Y of the steel strip (the depth direction of the slit), that is, the width increases toward the back of the slit. It is preferable to use the shape. At this time, the angles θ1 and θ2 formed by the both ends 44A and 44B of the tip plate with respect to the thickness direction Y are preferably 10 to 60 degrees, respectively. By setting each of θ1 and θ2 to 10 degrees or more, when the tip plate 44 moves in the plate width direction inside the slit 33, it is possible to apply a force for pushing the splash to the outside of the slit 33. It can be removed efficiently. However, if θ1 and θ2 are too large, the force that can be applied to the splash becomes small in the first place. Therefore, it is preferable that θ1 and θ2 be 60 degrees or less, respectively.

The material of the tip plate 44 is not particularly limited, but it is preferable to use a material coated with a substance such as WC, Al ₂ O ₃ , or ZrO ₂ that has no affinity for molten metal such as molten zinc. By doing so, the formation of an alloy layer between the molten metal and the tip plate 44 is suppressed, and the splash adhering to the slit 33 can be easily removed.

(Drive mechanism 50)
With reference to FIG. 2, the drive mechanism 50 includes a linear guide 52, a ball screw 53, a coupling 54, and an electric motor 55, and can move the cleaning jig 40 along the plate width direction X. The linear guide 52 includes a rail 52A and a block 52B. The rail 52 </ b> A is installed on the horizontal surface of the upper nozzle member 31 and extends along the plate width direction X. The block 52B engages with the rail 52A and can move along the rail 52A. Further, the block 52B is connected to the connecting portion 41 of the cleaning jig. The ball screw 53 includes a shaft 53A extending along the plate width direction X above the linear guide 52, and a block 53B attached to the shaft and movable along the shaft. The block 53B and the block 52B are connected. One end of the ball screw shaft 53 </ b> A is connected to an electric motor 55 for driving the ball screw via a coupling 54. By operating the electric motor 55, the ball screw block 53B moves along the shaft 53A. As a result, the cleaning jig 40 can move in the plate width direction X along the linear guide 52, and the tip plate 44 can move in the slit 33 along the plate width direction X. In this embodiment, since the combination of the ball screw 53 and the electric motor 55 is used as the drive mechanism, the tip plate 44 can be moved and stopped at an arbitrary position with respect to the plate width direction X in the slit.

The linear guide 52 is arranged on the entire length in the width direction of the wiping nozzle 30 and on the outside thereof so that the tip plate 44 can move to an arbitrary position in the slit width direction in the slit 33 and can stand by outside the slit during normal operation. It is installed over the length. Although the kind of electric motor 55 is not specifically limited, For example, a servo motor or a step motor is preferable.

(Control unit 70)
Referring to FIG. 2, control unit 70 controls the operation of drive mechanism 50. In the present embodiment, the control unit 70 controls the operation of the electric motor 55 for driving the ball screw, and operates the electric motor 55 in response to input of measurement data output from a displacement sensor 80 described later.

(Displacement sensor 80)
Referring to FIG. 2, displacement sensor 80 is located in the vicinity of slit 33 and detects the presence and position of scattered molten metal in slit 33. From the viewpoint of measurement accuracy and measurable distance, in the present embodiment, the displacement sensor 80 is preferably a non-contact optical displacement sensor. For example, one-dimensional laser displacement meter LK-G5000 series manufactured by Keyence Corporation can be suitably used. Such a one-dimensional laser displacement sensor is installed outside the end portion in the plate width direction X of the slit 33, and the inside of the slit 33 is always monitored along the plate width direction X by the sensor. As a result, when the splash P adheres to the slit 33, information indicating that the splash P has adhered and information on the adhesion position (splash position information in the plate width direction X) are instantaneously output as data from the variation amount of the measured value. be able to. The output data is sent to the control unit 70.

(Splash removal method)
A method for removing splash adhering to the slit by the gas wiping apparatus 20 having the above configuration will be described with reference to FIG. During the normal operation of passing the steel strip S through the continuous molten metal plating facility 100, the gas wiping device 20 injects gas toward the steel strip S, while the displacement sensor 80 passes the inside of the slit 33 along the plate width direction X. Always monitor. During normal operation, the cleaning jig 40 is at a predetermined standby position so that the tip plate 44 is detached from the slit 33.

When the displacement sensor 80 detects that the splash P has adhered to the slit 33, the displacement sensor 80 transmits information indicating the presence of the splash P and position information of the splash in the plate width direction X to the control unit 70.

The control unit 70 receives the position information of the splash from the displacement sensor 80 and operates the electric motor 55. Specifically, the tip plate 44 is inserted into the slit 33 and further moved in the slit along the plate width direction X to the splash position. In this way, the splash P existing in the slit is scraped off and removed by the tip plate 44.

According to the present embodiment, the position information of the splash in the plate width direction can be grasped by the displacement sensor 80, and the tip plate 44 can be automatically moved and stopped at an arbitrary position in the slit in the plate width direction X. Therefore, the splash can be automatically and efficiently removed quickly without moving the tip plate 44 from one end of the slit to the other end in the full width.

Further, it is preferable that the control unit 70 causes the tip plate 44 to reciprocate a predetermined amount of movement in the plate width direction X around the position of the splash. Splash can be more reliably removed by the tip plate 44 reciprocating in small increments about the position of the splash. The width of the reciprocating motion in the plate width direction X is not particularly limited, but can be 5 to 50 mm.

When moving the tip plate 44 in the plate width direction X, the thrust is preferably 30 to 100 kgf and the moving speed is preferably about 200 to 1000 mm / s.

Whether or not the splash has been removed can be confirmed by periodically returning the tip plate 44 to the standby position during the removal operation and visually observing the surface of the steel strip to see if surface defects due to film thickness unevenness have disappeared. This can be done by checking.

(Second Embodiment)
The drive mechanism 50 is preferably capable of moving the tip plate 44 in the plate thickness direction Y and / or the plate length direction Z in addition to the plate width direction X in the slit 33. Splash can be removed more quickly and reliably by such movement of two or three axes. Hereinafter, as a second embodiment of the present invention, referring to FIGS. 6 to 8, a gas having a drive mechanism 50 capable of biaxially moving the tip plate 44 in the slit width 33 in the plate width direction X and the plate thickness direction Y will be described. A wiping device will be described. In addition, this embodiment uses the description of 1st Embodiment except the structure of the drive mechanism 50. FIG.

Referring to FIG. 6, the drive mechanism 50 includes an upper box 51 and a lower box 61. 7 and 8 in addition to FIG. 6, the upper box 51 accommodates a linear guide 52, a ball screw 53, a coupling 54, an electric motor 55 for driving the ball screw, and an electric motor 56 for driving the pinion. . Referring to FIG. 8 in addition to FIG. 6, the lower box 61 accommodates a linear guide 62 and a rack and pinion mechanism including a rack gear 63 and a pinion 64. 6 to 8, the dimensions of each element of the drive mechanism 50 are shown exaggerated with respect to the wiping nozzle 30 for the purpose of explaining a mechanism for moving the tip plate 44 in the X and Y directions. Yes.

First, a mechanism for moving the tip plate 44 in the plate width direction X will be described with reference to FIGS. Two linear guides 52 are installed in the upper box 51 in parallel. Each linear guide 52 includes a rail 52A and a block 52B. Each rail 52A is fixed to the upper box 51 and extends along the plate width direction X. Each block 52B fits with each rail 52A and can move along each rail 52A. Further, one of the blocks 52B is connected to the connection part 41 of the cleaning jig. The ball screw 53 includes a shaft 53A extending along the plate width direction X, and a block 53B attached to the shaft and movable along the shaft. The block 53B and the two blocks 52B are connected. One end of the ball screw shaft 53 </ b> A is connected to an electric motor 55 for driving the ball screw via a coupling 54. By operating the electric motor 55, the ball screw block 53B moves along the shaft 53A. As a result, the cleaning jig 40 moves in the plate width direction X along the two linear guides 52, and the tip plate 44 can move in the slit 33 along the plate width direction X. In this embodiment, since the combination of the ball screw 53 and the electric motor 55 is used as the drive mechanism, the tip plate 44 can be moved and stopped at an arbitrary position with respect to the plate width direction X in the slit.

Next, a mechanism for moving the tip plate 44 in the thickness direction Y will be described with reference to FIGS. First, two linear guides 62 are accommodated in the lower box 62. Each linear guide 62 includes a rail 62A and a block 62B. Each rail 62A is fixed to the lower box 61 and extends along the thickness direction Y. Each block 62B is fitted to each rail 62A, is movable along each rail 62A, and is fixed to the upper box 51. The rack gear 63 is fixed to the lower box 61. A rotation shaft 56 </ b> A of a pinion driving electric motor 56 accommodated in the upper box 51 is inserted into the hollow portion of the pinion 64. Therefore, when the electric motor 56 is operated, the pinion 64 meshed with the fixed rack gear 63 moves in the plate thickness direction Y along the two linear guides 62. Since the electric motor 56 fixed to the upper box 51 is also connected to the pinion 64, the upper box 51 slides in the plate thickness direction Y with respect to the fixed lower box 61 as the pinion 64 moves. . As a result, the cleaning jig 40 also moves in the plate thickness direction Y along the two linear guides 62, and the tip plate 44 can move in the slit 33 along the plate thickness direction Y.

In this embodiment, upon receiving the position information of the splash in the plate width direction X from the displacement sensor 80, the tip plate 44 is moved as follows. First, the electric motor 55 for driving the ball screw is operated, the tip plate 44 is inserted into the slit 33, and further, the inside of the slit is moved along the plate width direction X to the splash position. Thereafter, the reciprocating motion in the plate width direction X centered on the position of the splash by the control of the electric motor 55 and the reciprocating motion in the plate thickness direction Y by the control of the pinion driving electric motor 56 are performed alternately or simultaneously. Can do. As described above, the tip plate 44 reciprocates little by little in the plate width direction X and the plate thickness direction Y around the position of the splash, so that the splash can be more reliably removed. The width of the reciprocating motion in the thickness direction Y is not particularly limited, but can be 5 to 50 mm.

When moving the tip plate 44 in the thickness direction Y, the thrust is preferably 30 to 100 kgf and the moving speed is preferably about 10 to 50 mm / s.

(Modification of displacement sensor)
The displacement sensor 80 can acquire two-dimensional or three-dimensional position information including the position in the plate thickness direction Y and / or the plate length direction Z in addition to the position in the plate width direction X with respect to the position information of the splash. It is preferable. Thereby, more accurate position information of the splash adhered in the slit can be obtained. For example, by using a two-dimensional laser displacement sensor such as the Keyence Corporation two-dimensional laser displacement meter LJ-V series as the displacement sensor 80, the two-dimensional position information of the splash in the plate width direction X and the plate thickness direction Y is acquired it can.

Further, by always reciprocating the two-dimensional displacement sensor in the range of the slit 33 along the plate length direction Z of the steel strip, the plate width direction X, the plate thickness direction Y, and the plate length with respect to the splash position information. Splash three-dimensional position information about the direction Z can be acquired.

Regarding the movement of the cleaning jig 40 when XY two-dimensional position information or XYZ three-dimensional position information is obtained, (1) the tip plate 44 is moved in the X direction to the splash position, as in the first and second embodiments. (2) A mode in which the tip plate 44 is moved in the X direction to the position of the splash, and then reciprocated in the X direction in small increments around the position of the splash, and (3) the tip plate 44 is moved in the X direction to the position of the splash. And then reciprocatingly moving in the XY directions around the position of the splash.

The galvanized steel sheet can be manufactured by applying the gas wiping apparatus 20 of the present invention and the manufacturing method of the hot dip galvanized steel strip, which is not subjected to alloying after the hot dip galvanizing process. Although both a plated steel plate (GI) and a plated steel plate (GA) subjected to an alloying treatment are included, the present invention is not limited to this, and it is possible to manufacture all hot-dip plated steel plates.

Using the continuous galvanizing equipment having the wiping nozzle shown in FIG. 3 and having the basic configuration shown in FIG. The hot dip galvanized steel strip was manufactured by entering the hot dip galvanizing bath at s. The dimension of the slit of the wiping nozzle is 2000 mm for length L1, 20 mm for depth L2, and 1.2 mm for width L3.

A cleaning jig having a tip plate with dimensions of 1.0 mm in thickness, 30 mm in width, and 20 mm in length was used. The shape of the tip plate was rectangular in Invention Examples 1 to 3 and Comparative Example, and in Invention Example 4, θ1 and θ2 were variously changed in the range of 0 to 80 degrees. When θ1 and θ2 are not 0 degrees, the width of 30 mm is the width on the front side of the slit. In each invention example, the XY two-dimensional position information of the splash can be acquired by using a two-dimensional laser displacement sensor of Keyence Corporation two-dimensional laser displacement meter LJ-V series.

Hereinafter, the drive mechanism and tip plate moving procedure used in each invention example and comparative example will be described.

(Invention Example 1)
The driving mechanism is configured to be able to move the tip plate in the X direction as shown in FIG. When the displacement sensor detected that the splash adhered to the slit, the control unit operated the electric motor to move the tip plate from the standby position to the splash position in the X direction. Thereafter, the tip plate was returned to the standby position, and the surface of the steel strip was visually observed to confirm whether or not the surface defects due to the film thickness unevenness had disappeared. When the surface defect did not disappear, the splash was not completely removed, so the tip plate was moved again from the standby position to the splash position in the X direction and then returned to the standby position. This was done until the surface defects disappeared and the splash could be removed.

(Invention Example 2)
The driving mechanism is configured to be able to move the tip plate in the X direction as shown in FIG. When the displacement sensor detected that the splash adhered to the slit, the control unit operated the electric motor to move the tip plate from the standby position to the splash position in the X direction. Thereafter, the tip plate was reciprocated in the X direction for 10 seconds with a small distance of 20 mm around the position of the splash. Thereafter, the tip plate was returned to the standby position, and the surface of the steel strip was visually observed to confirm whether or not the surface defects due to the film thickness unevenness had disappeared. When the surface defect did not disappear, the splash was not completely removed, so the tip plate was moved again in the same manner and returned to the standby position. This was done until the surface defects disappeared and the splash could be removed.

(Invention Example 3)
The driving mechanism has a structure shown in FIGS. 6 to 8 and can move the tip plate in the XY directions. When the displacement sensor detected that the splash adhered to the slit, the control unit operated the electric motor to move the tip plate from the standby position to the splash position in the X direction. After that, the tip plate was reciprocated in the X direction for 5 seconds with a small distance of 20 mm around the position of the splash, and further reciprocated in the Y direction for 5 seconds with a small distance of 20 mm around the position of the splash. . Thereafter, the tip plate was returned to the standby position, and the surface of the steel strip was visually observed to confirm whether or not the surface defects due to the film thickness unevenness had disappeared. When the surface defect did not disappear, the splash was not completely removed, so the tip plate was moved again in the same manner and returned to the standby position. This was done until the surface defects disappeared and the splash could be removed.

(Comparative example)
The splash adhering in the slit was removed by the method described in Patent Document 2. That is, no displacement sensor was provided in the vicinity of the slit, and the presence or absence of splash was detected by a pair of distance sensors arranged with a steel plate in between. The tip plate was moved along the plate width direction X by an air cylinder instead of an electric motor. Since the air cylinder is used, the tip plate cannot be stopped at an arbitrary position in the plate width direction X in the slit, and one movement reciprocates from one end to the other end in the slit. When splash adhesion was detected, this reciprocation was performed. Whether or not the removal of the splash was completed was performed by visual observation of the steel strip surface as in Invention Examples 1 to 3, and the above reciprocating motion was repeated until the splash was completely removed.

<Evaluation of average work time and yield>
In the inventive examples 1 to 3 and the comparative example, the operation of removing the detected adhesion splash was performed 10 times, and the average operation time from the start of the operation to the completion of the operation was obtained. In addition, the yield of the steel strip was calculated on the assumption that the splash removal operation occurred once in 3 hours of the manufacturing process. The results are shown in Table 1.

As is clear from Table 1, in Examples 1 to 3, the average working time was significantly shortened compared to the comparative example, and a high yield was achieved.

(Invention Example 4)
The driving mechanism and the movement mode of the tip plate were the same as those of Invention Example 3. In the case of the invention example 4, in each case where θ1 and θ2 are variously changed in the range of 0 to 80 degrees, the results of the same evaluation of the average work time and the yield are shown in FIG. As is apparent from FIG. 9, when θ1 and θ2 are set to 10 to 60 degrees, the average work time can be particularly shortened, and the yield can be particularly increased.

According to the gas wiping apparatus of the present invention and the method for producing a molten metal plated steel strip, the molten metal splash adhering to the slit can be quickly removed. Therefore, the molten metal plated steel strip can be manufactured with a high yield.

DESCRIPTION OF SYMBOLS 100 Continuous molten metal plating equipment 10 Snout 12 Plating tank 14 Molten metal bath 16 Sink roll 18 Support roll 20 Gas wiping apparatus 30 Wiping nozzle 31 Upper nozzle member 32 Lower nozzle member 33 Injection port (slit)
34 hollow portion 35 gas supply path 36 gas supply pipe 40 cleaning jig 41 connection portion 42 base portion 43 bent portion 44 tip portion (tip plate)
DESCRIPTION OF SYMBOLS 50 Drive mechanism 51 Upper box 52 Linear guide 53 Ball screw 54 Coupling 55 Ball screw drive electric motor 56 Pinion drive electric motor 61 Lower box 62 Linear guide 63 Rack gear 64 Pinion 70 Control part 80 Displacement sensor S Steel strip P Splash L1 Slit Length L2 Slit depth L3 Slit width X Steel strip width direction (Slit length direction)
Y Steel strip thickness direction (slit depth direction)
Z Steel strip length direction (slit width direction)

Claims

A gas wiping device that adjusts the amount of molten metal deposited on the surface of the steel strip by blowing gas to the steel strip pulled up from the molten metal bath,
A wiping nozzle that constitutes the gas injection port and has a slit at the tip that extends in the width direction of the steel strip;
A cleaning jig that includes a tip plate positioned outside the slit and sized to be inserted into the slit;
A drive mechanism for moving the cleaning jig;
A control unit for controlling the operation of the drive mechanism;
A displacement sensor that is located in the vicinity of the slit, detects the presence or absence of scattered molten metal in the slit, and the position of the scattered molten metal in the plate width direction of the steel strip;
And the control unit operates the drive mechanism based on the position information of the scattered molten metal output from the displacement sensor, inserts the tip plate into the slit, and further passes through the slit. The gas wiping apparatus characterized by scraping and removing the scattered molten metal adhering to the inside of the slit by the tip plate by moving to the position of the scattered molten metal along the plate width direction of the steel strip.
The gas wiping apparatus according to claim 1, wherein the control unit causes the tip plate to reciprocate a predetermined amount of movement in the plate width direction around the position of the scattered molten metal.
The gas wiping apparatus according to claim 1 or 2, wherein the displacement sensor is a non-contact optical displacement sensor.
The gas wiping according to any one of claims 1 to 3, wherein the driving mechanism moves the tip plate in a plate thickness direction and / or a plate length direction in the slit in addition to the plate width direction. apparatus.
The gas wiping device according to any one of claims 1 to 4, wherein the drive mechanism includes an electric motor.
The displacement sensor acquires two-dimensional or three-dimensional position information including a position in a plate thickness direction and / or a plate length direction in addition to a position in the plate width direction with respect to the position information of the scattered molten metal. 6. The gas wiping device according to any one of 1 to 5.
The tip plate has a shape that becomes wider toward the back of the slit, and an angle θ formed by both ends of the tip plate with respect to the thickness direction of the steel strip is 10 to 60 degrees. The gas wiping device according to any one of the above.
Immerse the steel strip continuously in the molten metal bath,
A pair of gas wiping apparatuses according to any one of claims 1 to 7, which are disposed with a steel strip pulled up from the molten metal bath interposed therebetween, and gas is blown onto the steel strip to Adjust the amount of molten metal attached,
A method for producing a molten metal-plated steel strip that continuously produces a molten metal-plated steel strip.