JP2007284732A - Gas-wiping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas-wiping device capable of suppressing noise, the non-uniform coating weight caused by a turbulent impinging jet, and splash occurrence in the gas-wiping device of a hot-dip metal plating device for uniformly adjusting the thickness of a molten metal on the surface of a metal plate by immersing/passing the metal plate into/through the molten metal, then continuously pulling up the metal plate above the free surface of the molten metal and blowing an air flow from a pair of nozzles arranged across the metal plate. <P>SOLUTION: The gas-wiping device comprises: a slit closing mechanism capable of changing the positions of both ends of slits of a pair of nozzles opposing to each other; a slit width adjusting mechanism for adjusting the positions of both ends of the slits to the position of both ends of the metal plate; and a mechanism for adjusting the gas flow rate so that the discharging flow rate from the nozzles is constant. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

 In the present invention, after a metal plate is immersed in molten metal, the molten metal is continuously pulled up on the free surface of the molten metal, and an air flow is blown from a pair of nozzles arranged with the metal plate interposed therebetween to melt the molten metal on the surface of the metal plate. The present invention relates to a gas wiping apparatus for a molten metal plating apparatus that adjusts the thickness of the metal uniformly.

 FIG. 3 shows a front view and a cross-sectional view of the conventional gas wiping apparatus. After the metal plate 2 is immersed in the molten metal bath 3 using the sink roll 4, the metal plate 2 is continuously pulled up on the free surface of the molten metal, and from the nozzle 1 which is a pair of nozzles arranged with the metal plate interposed therebetween. An apparatus for uniformly adjusting the thickness of the molten metal on the surface of the metal plate by blowing the air flow 21 has been used conventionally, but the thickness of the molten metal on the surface of the metal plate is increased at the edge of the plate, and an edge overcoat is generated. It was. This is considered to be caused by the pressure of gas wiping decreasing at the edge, and countermeasures have been proposed conventionally. These can be broadly classified as 1) plates placed on the plate edge, 2) auxiliary nozzles, 3) equipment equipped with suction, 4) variable width direction of nozzle slit spacing, etc. In 3) to 3), the equipment was complicated, and maintenance work for adhesion such as splash was expensive. Therefore, it is considered that the method completed with the nozzle as in 4) is simple and the maintenance cost is reduced.

 FIG. 4 shows a front view and a cross-sectional view of one of the most common structures for countermeasures against edge overcoat disclosed in Patent Documents 1 to 5. The basic idea is that the gap d of the slit is not constant in the longitudinal direction of the nozzle but is narrow at the center and wide at both ends, so that the gas wiping pressure is injected at both ends of the metal plate so as not to decrease at the edges. The amount of gas ejection was set to be larger than that at the center. As devices for realizing this effect, devices of Patent Documents 1 to 5 have been devised.

 FIG. 5 shows a front view and a cross-sectional view taken along the arrow of the gas wiping apparatus disclosed in Patent Document 1. A load distribution is created by a plurality of actuators 31 in the longitudinal direction of the nozzle, a force is transmitted by the lever 33, and the nozzle lip 43 is elastically deformed and pushed up to make use of the fact that the nozzle closes. Distribution is made.

 FIG. 6 shows a front view and a cross-sectional view taken along the arrow of the gas wiping apparatus disclosed in Patent Document 2. A plurality of shielding plates 34 that can adjust the slit gap in the nozzle airway in the longitudinal direction of the nozzle are provided.

 FIG. 7 shows a front view and a cross-sectional view of the gas wiping device of Patent Document 3. The upper and lower lip 35 shapes of the gas discharge ports at the tip of the nozzle are slidable in the longitudinal direction with the same cubic curve shape, and a slit gap distribution is created in the longitudinal direction of the nozzle.

 FIG. 8 shows a front view and a cross-sectional view of the gas wiping apparatus disclosed in Patent Document 4. The movable plate 37 is locally pushed down by the movable roller 36 on the basis of the lever principle to create a slit gap distribution in the longitudinal direction of the nozzle.

FIG. 9 shows a front view and a cross-sectional view taken along the arrow of the static pressure pad of Patent Document 5. The GG ′ arrow sectional view is a sectional view of a portion closed by the adjustment nozzle plate 40, and the HH ′ arrow sectional view is a sectional view of a portion not blocked by the adjustment nozzle plate. By providing a pressure receiving plate 39 wider than the discharge hole and moving the adjustment nozzle plate 40 with the rod 41, the distance between the two sides in the strip plate width direction can be adjusted, but this suppresses the vibration of the metal plate. , Use is different.
JP-A-4-17552 JP-A-5-51716 JP-A-9-71852 Japanese Patent Laid-Open No. 5-138078 JP 56-123330 A

 In a method of narrowing the slit d in the longitudinal direction of the nozzle, which is one of the most common structures for countermeasures against edge overcoats in Patent Documents 1 to 5, narrower at the center and wider at both ends, it is outside the width of the metal plate. The opposing jets collide, the turbulent flow caused by the impinging jets affects the flow of the plate, the effect of suppressing the pressure drop at the plate edge is unstable, and splash is generated, reducing the quality of the plating. It was. Further, since the structure is complicated, the machining of the nozzle itself is complicated, and it becomes expensive due to countermeasures against thermal expansion and the like, which has not been realized. Further, Patent Documents 1 to 5 have the following problems.

In the method of FIG. 5 (FIG. 5), the structure is complicated and expensive. The actuator was fragile by heat.
In the method of Patent Document 2 (FIG. 6), the gas wraps around the space 48 from the shielding plate 34 to the slit of the nozzle, and there is no effect. In addition, the structure is complicated and expensive.

 In the method of Patent Document 3 (FIG. 7), since the uniform nozzle width is not obtained, the basis weight distribution cannot be made uniform in the width direction. In addition, machining of a cubic curve shape is necessary and expensive.

In the method of Patent Document 4 (FIG. 8), the structure is complicated and expensive.
In the method of Patent Document 5 (FIG. 9), although it becomes a static pressure pad, the wiping force is weak. In addition, when used for wiping, the liquid accompanying the metal plate tends to adhere to the lower end of the static pressure pad, which increases the maintenance cost.

 In addition, Patent Documents 1 to 5 may cause environmental problems due to large noise caused by jet collision.

 In view of the above problems, the present invention provides a gas wiping device capable of stably suppressing edge overcoat while suppressing occurrence of splash while reducing unevenness in the basis weight distribution, and can also reduce noise. An object is to provide a gas wiping device.

 In order to achieve the above object, the present inventor has extensively studied a gas wiping apparatus. As a result, the following findings were obtained.

 When numerical fluid analysis is performed on the gas flow from the opposing wiping nozzle, the jet flows along the surface of the metal plate in the presence of the metal plate, whereas the opposing wiping nozzle in the absence of the metal plate It was found that the flow of gas from the vortex caused Karman vortex-like turbulent flow up and down by repeated fluctuations in pressure over time due to collisions between jets. It was found that this Karman vortex turbulent flow created an unstable velocity gradient at the plate edge between the flow along the surface of the metal plate, generated shear force, and caused edge overcoat. . In the present invention, in the vicinity of the plate edge, the positions of both ends of the slits of both nozzles of the pair of opposed nozzles are adjusted to both ends of the metal plate, thereby creating a state in which the jets from the opposed nozzles do not collide with each other. As a result, there is no pressure win-lose between the jets, so Karman vortices are not generated in the vertical direction, and the flow along the metal plate is an unstable velocity gradient with turbulent flow that changes rapidly over the plate edge. Therefore, it was found that the edge overcoat can be stably suppressed while the occurrence of splash is suppressed. It was also found that noise can be reduced.

The present invention has been made on the basis of the above findings, and the gist thereof is the following contents as described in the claims.
(1) After the metal plate is immersed in the molten metal, the metal plate is continuously pulled up on the free surface of the molten metal, and airflow is generated from a pair of nozzles arranged opposite to each other with the metal plate interposed therebetween. In a gas wiping apparatus for molten metal plating that uniformly adjusts the thickness of the molten metal on the surface of the metal plate, a slit closing mechanism that makes variable the positions of both ends of the slits of both of the pair of opposed nozzles A gas wiping apparatus comprising: a slit width adjusting mechanism that adjusts both end positions of the slit to both end positions of the metal plate; and a mechanism that adjusts the gas flow rate so that the discharge flow rate of the nozzle is constant. .
(2) The slit width adjusting mechanism has an adjustment function in which the absolute value L of the difference between the position of the slit opening of the nozzle and the plate edge position and the distance G between the metal plate and the nozzle satisfy the following expression (A). The gas wiping device according to (1), characterized in that

L ≦ 2G (A)
(3) A slit gap d1 that satisfies the following equation (B) is provided on the outside of the slit gap d and the slit opening of the slit width Ws of the nozzle facing the metal plate having a plate width Ww. The gas wiping apparatus according to (1) or (2), wherein a slit is provided.
0 ≦ d1 ≦ 0.3d (B)
(4) The gas wiping apparatus according to any one of claims 1 to 3, wherein the slit width adjusting mechanism has a slit closing rod that slides in the slit width direction in the nozzle as a slit closing member. .
(5) The gas according to any one of (1) to (3), wherein the slit width adjusting mechanism has a spacer that slides in the slit width direction between the slits of the nozzle as a slit closing member. Wiping device.
(6) The slit width adjusting mechanism includes nozzle constituent parts above and below the nozzle that change the end position by sliding in the slit width direction and form the slit end by a step. (1) The gas wiping apparatus according to any one of to (3).
(7) Any of (1) to (3), wherein the slit width adjusting mechanism has a function of adjusting both ends to the plate width by tilting the nozzle in the plate width direction as a slit closing member. The gas wiping apparatus according to claim 1.
(8) The apparatus according to any one of (1) to (7), characterized in that it has a mechanism for adjusting both ends of the slit of the nozzle when the width of the metal plate is changed and when the metal plate is meandered. Gas wiping equipment.

 According to the present invention, by adjusting the both end positions of the slits of both nozzles of the pair of facing nozzles to the both end positions of the metal plate, a state is created in which jets from the facing nozzles do not collide violently. As a result, turbulent flow is not generated by collisions between jets, so Karman vortices are not generated in the vertical direction, and the flow along the surface of the metal plate is unstable with turbulent flow that changes rapidly in time even at the plate edge. Therefore, a gas wiping apparatus capable of stably suppressing edge overcoat while suppressing occurrence of splash can be provided. Moreover, the gas wiping apparatus which can also reduce noise was able to be provided.

 After the metal plate is immersed in the molten metal, it is continuously pulled up on the free surface of the molten metal, and the thickness of the molten metal on the surface of the metal plate is blown by blowing an air flow from a pair of nozzles placed across the metal plate. In a gas wiping apparatus of a molten metal plating apparatus for uniform adjustment, a mechanism for adjusting both end positions of slits of both nozzles of a pair of opposed nozzles to both ends of a metal plate is provided. 1, FIG. 2, FIG. 10 to FIG.

  FIG. 1 is a front view and a cross-sectional view of the gas wiping device according to the present invention. (A) is a front view, (b) is a cross-sectional view taken along arrow AA ′, and (c) is a cross-sectional view taken along arrow BB ′. A nozzle in which the metal plate 2 having a plate width of 600 to 1800 mm is immersed in the molten metal 3 at a plate speed of 100 to 150 mpm, and then continuously pulled up on the free surface of the molten metal, and the nozzle is disposed with the metal plate 2 interposed therebetween. The airflow 21 is sprayed from one pair to uniformly adjust the thickness of the molten metal on the surface of the metal plate. Arrow AA ′ shows a cross-sectional view of a portion with the metal plate 2, and arrow BB ′ shows a cross-sectional view of a portion without the metal plate. In the portion where the metal plate is present, there is no slit closing member in the slit 9 of the nozzle, and in the portion where there is no metal plate, the slit closing mechanism 42 is installed in the slit 9 of the nozzle. In order to keep the wiping force constant corresponding to the change in the slit area as the slit width is changed, the gas flow rate is adjusted so that the discharge flow rate becomes constant.

  FIG. 2 is a front view and a cross-sectional view showing the gas wiping nozzle of the present invention. (A) is a front view, (b) is a side sectional view. The slit closing mechanism 42 can change the slit width Ws by moving the rod 41 in the slit width direction using an actuator. The slit closing mechanism 42 is disposed so as to close the slit portion from the inside of the nozzle.

 10A and 10B are diagrams showing a gas flow in the vicinity of a conventional plate edge, where FIG. 10A is a front view seen from a direction perpendicular to the metal plate, and FIG. 10B is a cross-section with a metal plate seen from the side of the plate. CC ′ arrow cross-sectional view showing the flow 11 of the plate collision jet of FIG. 4C, (c) is a cross-sectional view taken along the DD ′ arrow showing the flow 12 of the out-of-plate collision jet in a cross section without the metal plate viewed from the side of the plate. d) is a plan view of (a).

 When the numerical fluid analysis was performed on the gas flow from the opposing wiping nozzle, it was found that the plate collision jet 11 and the off-plate collision jet 12 were greatly different in the flow state. Where there is a metal plate, the jet flows along the surface of the metal plate, whereas in the absence of the metal plate, the gas flow from the opposing wiping nozzle causes the jets to lose pressure over time. It was found that Karman vortex-like turbulent flow was caused by repeating the fluctuation. Between this Karman vortex-like turbulent flow and the flow along the surface of the metal plate, interference 14 between the plate collision jet 11 and the off-plate collision jet 12 occurs slightly above the collision jet line 10 at the plate edge 13. Then, an unstable velocity gradient is generated, a shear force is generated, a separation flow 18 is generated, an outward shear force 19 is applied to the molten metal on the plate, the molten metal is moved in the edge direction, and an edge overcoat is formed. It was found that was causing.

 FIG. 11 is a diagram showing the gas flow in the vicinity of the plate edge in the present invention. (a) is a front view seen from a direction perpendicular to the metal plate, (b) is a cross-sectional view taken along the arrow EE ′ showing the flow 11 of the plate collision jet in a cross section with the metal plate seen from the side of the plate, ) Is a cross-sectional view taken along the line FF ′ showing the flow 12 of the out-of-plate collision jet in a cross section without a metal plate viewed from the side of the through plate, and (d) is a plan view of (a). By installing a mechanism that adjusts both ends of the slits of both nozzles of the pair of opposing nozzles to both ends of the metal plate, jets from the opposing nozzles do not collide with each other, and pressure wins and losses occur between the jets Therefore, the Karman vortex is not generated vertically, and the flow along the metal plate even at the plate edge does not create an unstable velocity gradient with the turbulent flow that changes rapidly with time. It was found that the edge overcoat can be stably suppressed while suppressing the occurrence of splash. It was also found that noise can be reduced.

 In the present invention, there is no collision jet outside the plate edge, but there is a velocity gradient. There was a concern about the generation of vortices, etc., and when numerical fluid analysis was performed, although a low pressure part was generated due to the velocity gradient and an unstable state was obtained, it was compared with Karman vortex-like turbulence caused by impinging jets. I found that the impact was very small. Further investigation revealed that when a collision flow was generated slightly off the plate, the velocity gradient was reduced, the influence of the unstable state was further reduced, and Karman vortices were not generated. In order to generate a slight collision flow at this time, the slit gap must be 30% or less of the nozzle.

 FIG. 12 is a front view and a cross-sectional view taken along the arrow showing the positional relationship of the slit closing mechanism in the present invention. As a result of numerical fluid analysis using the position as a parameter for the allowable range of the difference between the position of the slit opening end of the nozzle and the position of the plate edge, the absolute value L of the difference between the position of the slit opening end of the nozzle and the position of the plate edge L When the distance G between the metal plate and the nozzle satisfies the equation (A), it has been found that the turbulent flow of the collision jet outside the metal plate does not affect.

L ≦ 2G (A)
FIG. 13 is a cross-sectional view showing a slit closing mechanism in which both end positions of the slit of the nozzle are variable. FIG. 13 (a) is a diagram in which a slit closing rod that is slid in the slit width direction is installed in the nozzle as a slit closing mechanism that makes the both end positions of the nozzle slit variable. In this method, there is no space 48 to the slit of the nozzle in FIG. 6, and no gas wrap-around occurs, and the positions of both ends of the slit can be adjusted reliably. Moreover, since it is from the inside of a nozzle, there exists an advantage that it is easy to align the position of a slit obstruction | occlusion rod.

  FIG. 13B is a diagram in which spacers that are slid in the slit width direction are installed between the slits of the nozzles. There was no space 48 to the slit of the nozzle in FIG. 6, and no gas wraparound occurred, and the positions of both ends of the slit could be adjusted reliably.

  FIG. 13C is a diagram in which a closing lid is installed outside the slit. In (c), there is a problem that the splash is reattached, and the gap between the nozzle and the metal plate is about 5 to 10 mm.

  FIG. 14 is a view of the present invention showing a mechanism for adjusting both ends of the slit of the nozzle of the gas wiping device when the plate width is changed or meandering. The closing rod 42 is pulled out from both ends of the opposing nozzle 1 so that the position can be adjusted. Since the actual machine changes the plate width and causes meandering, the positions of both ends of the nozzle slit are adjusted using an actuator so that both ends of the metal plate are optically detected at all times and the meandering of the metal plate is followed. did.

  FIG. 15 is a diagram showing the distribution of the slit gap of the nozzle. Diagonal lines indicate the slit shape of the nozzle.

 FIG. 15D shows the conventional slit interval distribution of FIG. 3, and FIG. 15E shows the conventional slit interval distribution of FIG. In both cases, turbulent flow that generates edge overcoat was generated by the impinging jet in an area wider than the plate width.

 FIGS. 15A and 15B are slit spacing distributions that satisfy the formula (A). The case where the slit width Ws is wider than the plate width Ww is (a), and the case where it is narrow is (b). The distance G between the metal plate and the nozzle in FIG. 12 is set to about 5 mm. At this time, due to the spread and attenuation of the jet when it reaches the metal plate, the difference between the position of the slit opening end and the position of the plate edge L is prevented so as not to generate edge overcoat without increasing the turbulent flow at the plate edge. The allowable value is 10 mm or less from the equation (A). Actually, taking into account the meandering of the metal plate, and installing it at L = 0mm, for the meandering of about 5mm of the metal plate, no violent turbulence will be generated at the plate edge, so edge overcoat is applied. It was possible to prevent it from occurring. For meandering exceeding 5 mm, the slit closing mechanism is moved.

  FIG. 15C shows a slit interval distribution that satisfies the equation (B). In (c), a slit having a gap d1 = 0.2 mm and a length L2 = 10 mm is formed on the outer side of both ends of the slit gap d and the slit width Ws of the nozzle having the nozzle width Wn facing the metal plate having the plate width Ww. Was installed. Since the slit gap d is 1 mm, the position satisfies the formula (B).

0 ≦ d1 ≦ 0.3d (B)
When the distance G between the metal plate and the nozzle is about 5 mm, if L = 0 mm as described above, turbulent fluctuation can be suppressed with respect to the meandering of about 5 mm of the metal plate. If slits with gap d1 and length L2 are attached to the outside of both ends of the slit opening, it is considered that the velocity gradient of the jet at the edge of the plate can be relaxed. There is also a concern that the current will have an adverse effect. When the numerical fluid analysis was performed using the gap d1 as a parameter for the allowable range of the gap d1, it was found that the influence of the turbulent flow of the impinging jet outside the metal plate does not occur if the equation (B) is satisfied. The gas flow from the slit gap of d1 has an effect of relaxing the velocity gradient while suppressing the turbulent flow caused by the conventional collision jet in a region where there is a concern about the velocity gradient where there is no collision jet outside the plate edge. it is conceivable that.

 FIG. 15 (f) shows the slit interval distribution of the present invention, and the method of FIG. 17 is used to easily realize this distribution.

FIG. 16 is a front view and a cross-sectional view of the gas wiping device according to the present invention. (A) is a structure in which the closing rod is slid to satisfy the formula (A), and (b) is a slit gap narrower than the slit gap of the plate portion at the end of the closing rod to satisfy the equation (B). It has a structure.
FIG. 17 is a front view and an arrow sectional view showing another embodiment of the gas wiping apparatus of the present invention. As a slit closing mechanism that makes the both end positions of the nozzle slit variable, the end position is changed by sliding in the slit width direction, and the nozzle component parts above and below the nozzle that form the slit end with a step are installed . (a) shows the case where the slit gap is constant with the slit width. (b) shows the case where the slit gap increases at the slit end. The slit end is about 50mm from the edge, but the slit gap cannot be changed, but if the optimal slit gap distribution is determined in advance, the slit width can be changed by moving the top and bottom of the nozzle in the slit width direction. Is possible. Even when the plate width is changed from 600 mm to 1200 mm, for example, the slit end is about 50 mm from the edge, and the effect of increasing the slit gap at the edge does not extend beyond the edge, so a stable effect can be obtained even when the plate width is changed. It is done.

 FIG. 18 is a front view and a cross-sectional view of the gas wiping apparatus having the same effect as the present invention. As a slit closing mechanism that makes the positions of both ends of the slit of the nozzle variable, both ends are installed in accordance with the plate width by inclining the nozzle in the plate width direction. The same effect could be obtained by installing the nozzles diagonally on the left and right sides and adjusting both ends to the width of the plate. That is, the slit end can be adjusted to the plate width without using the slit closing mechanism by making the height difference of the nozzles in the width direction while maintaining a mirror image relationship between the pair of nozzles with respect to the plate surface. In addition, when used in combination with the slit closing mechanism 42, the slit interval can be quickly changed.

 An embodiment of the present invention will be described with reference to FIGS.

  FIG. 14 is a view of the present invention showing a mechanism for adjusting both ends of the slit of the nozzle of the gas wiping device when the plate width is changed or meandering. The closing rod 42 is pulled out from both ends of the opposing nozzle 1 so that the position can be adjusted. In the embodiment, the plate width is changed between 600 to 1800 mm, and meandering of about 5 mm occurs. Therefore, the actuator is always detected optically at both ends of the metal plate and follows the meandering of the metal plate. The position of both ends of the slit of the nozzle was adjusted.

  FIG. 12 is a view showing the positional relationship of the slit closing mechanism in the present invention. The absolute value L of the difference between the position of the slit opening end of the nozzle and the position of the plate edge was set to the meandering amount 5 mm. Since the distance G between the metal plate and the nozzle is 5 mm, the expression (A) is satisfied, and the turbulent flow of the collision jet outside the metal plate does not affect.

L ≦ 2G (A)
As described above, by adjusting the both end positions of the slits of both nozzles of the pair of opposed nozzles to the both end positions of the metal plate, a state in which jets from the opposed nozzles do not collide violently was created. As a result, turbulent flow is not generated by collisions between jets, so Karman vortices are not generated in the vertical direction, and the flow along the surface of the metal plate is unstable with turbulent flow that changes rapidly in time even at the plate edge. Therefore, the non-uniformity of the basis weight distribution is reduced to half that of the prior art, and a gas wiping apparatus capable of stably suppressing the edge overcoat while suppressing the occurrence of splash can be provided. Moreover, the gas wiping apparatus which can also reduce noise was able to be provided.

It is the figure which showed the gas wiping apparatus of this invention. It is the figure which showed the gas wiping apparatus of this invention. It is the figure which showed the conventional gas wiping apparatus. It is the figure which showed the conventional gas wiping apparatus. It is the figure which showed the conventional gas wiping apparatus. It is the figure which showed the conventional gas wiping apparatus. It is the figure which showed the conventional gas wiping apparatus. It is the figure which showed the conventional gas wiping apparatus. It is the figure which showed the conventional gas wiping apparatus. It is the figure which showed the gas flow in the vicinity of the conventional board edge. It is the figure which showed the gas flow in the board edge vicinity in this invention. It is the figure which showed the positional relationship of the slit obstruction | occlusion mechanism in this invention. It is the figure which showed the slit obstruction | occlusion mechanism which makes the both ends position of the slit of a nozzle variable. It is the figure which showed the gas wiping apparatus of this invention. It is the figure which showed distribution of the space | interval of the slit of a nozzle. It is the figure which showed the gas wiping apparatus of this invention. It is the figure which showed the gas wiping apparatus of this invention. It is the figure which showed the gas wiping apparatus which has the same effect as this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle 2 Metal plate 3 Molten metal bath 4 Sink roll 5 Support roll 9 Nozzle slit 10 Collision jet line 11 Plate collision jet 12 Off-plate collision jet 13 Plate edge 14 Interference of flow of plate collision jet and off-plate collision jet 18 Separation flow 19 Shear force 21 Airflow from nozzle 31 Actuator 32 Support point 33 Lever 34 Shield plate 35 Sliding nozzle lip 36 Roller 37 Movable plate 38 Static pressure pad 39 Pressure receiving plate 40 Adjustment nozzle plate 41 Rod 42 Slit closing mechanism 43 Nozzle lip 44, 45 Nozzle component parts above and below the nozzle that change the end position by sliding in the slit width direction and form the slit end with a step 47 Sliding part 48 Space from the shielding plate to the slit part of the nozzle

Claims (8)

  After the metal plate is immersed in the molten metal, the metal plate is continuously pulled up on the free surface of the molten metal, and airflow is blown from a pair of nozzles arranged opposite to each other with the metal plate interposed therebetween. In the gas wiping apparatus for molten metal plating that uniformly adjusts the thickness of the molten metal on the surface of the metal plate, a slit closing mechanism that makes variable both end positions of the slits of both of the pair of opposed nozzles, A gas wiping apparatus comprising: a slit width adjusting mechanism for adjusting both end positions of the slit to both end positions of the metal plate; and a mechanism for adjusting a gas flow rate so that a discharge flow rate of the nozzle becomes constant. The slit width adjusting mechanism has an adjustment function in which the absolute value L of the difference between the position of the slit opening of the nozzle and the plate edge position and the distance G between the metal plate and the nozzle satisfy the following expression (A). The gas wiping apparatus according to claim 1.
L ≦ 2G (A) A slit having a slit gap d1 satisfying the following expression (B) is installed outside the both ends of the slit gap d and the slit opening of the slit width Ws of the nozzle of the nozzle width Wn facing the metal plate of the plate width Ww. The gas wiping apparatus according to claim 1 or 2, wherein
0 ≦ d1 ≦ 0.3d (B)   The gas wiping apparatus according to any one of claims 1 to 3, wherein the slit width adjusting mechanism includes a slit closing rod that slides in the slit width direction in the nozzle as a slit closing member.   The gas wiping apparatus according to any one of claims 1 to 3, wherein the slit width adjusting mechanism has a spacer that slides in the slit width direction between the slits of the nozzle as a slit closing member.   The slit width adjusting mechanism has nozzle constituent parts above and below the nozzle that change the end position by sliding in the slit width direction and form the slit end by a step. The gas wiping apparatus of any one of Claims.  The slit width adjusting mechanism as a slit closing member has a function of adjusting both ends to the plate width by inclining the nozzle in the plate width direction. Gas wiping equipment. The gas wiping apparatus according to any one of claims 1 to 7, further comprising a mechanism that adjusts both ends of the slit of the nozzle when the width of the metal plate is changed and when the metal plate is meandered.

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