JP2007031776A - Hot-dip galvanizing device, and hot-dip galvanized metal strip manufacturing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot-dip galvanizing device capable of suppressing production and deposition of dross as a zinc ingot is charged in a molten zinc pot with a simple mechanism, and a hot-dip galvanized metal strip manufacturing method using the same. <P>SOLUTION: An ingot receiver 80 having a shape capable of supporting the lower end of a zinc ingot 46 is provided immediately below the charging position of the zinc ingot 46 and above the upper end of a molten zinc discharging port 471 of a heating device 47 added to a pot 40. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hot dip galvanizing apparatus and a method for producing a hot dip galvanized metal strip using the same.

  Methods for galvanizing metal plates such as steel sheets (including metal strips) can be broadly divided into electrogalvanization and hot dip galvanization, both of which are widely used. In suitable hot dip galvanizing, zinc inside and outside 450 ° C. heated and melted is stored in a hot galvanized pot (hereinafter referred to as “pot”), and a galvanizing is performed by immersing and taking out a metal plate. .

In FIG. 11, the outline | summary of the continuous hot-dip galvanizing line 100 of a general steel strip is shown.
A payoff reel 10 unwinds a steel strip S wound in a coil shape. When there are two reels and the unwinding of the tail end of the steel strip S from one reel is completed, the tip of another steel strip S is unwound from the other reel, and the other steel strip S is unwound from the other reel. During the unwinding, the operation of setting the steel strip S wound in another coil (not shown) on the first reel is repeated alternately on both reels, and the welding machine 20 successively And the steel strip S are welded and supplied to the continuous hot dip galvanizing line 100.

  The entire length of the steel strip S is plated by going through a series of processes in which the steel strip S heated in the heating zone 30 is continuously passed through the molten zinc in the pot 40, dipped and taken out. Then, the steel strip S is cut by the cutting machine 50 with the welded portion as a target, and is wound by the tension reel 60. When the tail end of the steel strip S after cutting is finished with the reel on one side, the tip of another steel strip S after cutting is taken up with the other reel, and the other steel strip is taken up with the reel on the other side. While winding S, the operation of carrying out the coiled steel strip S from the first reel is repeated alternately on both reels. There is a case where zinc heated by the alloying furnace 70 and attached to the steel strip S is integrated with the steel strip S.

  An outline of the pot 40 and the main component equipment accompanying it is shown in FIG. 12. The steel strip S that has been passed through the snout 41 adjusted to an atmosphere that is difficult to oxidize is a sink roll 42 disposed in the pot 40. The direction of the band is changed upward by the above, and after passing through the warp correction roll 43, the molten zinc adhering to the surface of the steel strip S is adjusted within the target weight range by the gas G injected from the gas wiping device 44. Thereafter, a method of further passing the wiping roll 45 is generally taken.

In addition, as a method for newly supplying zinc lost by adhering to the surface of the steel strip S, as shown in FIG. 13, a normal temperature zinc ingot 46 is placed in the pot 40 as shown in FIG. 13. Generally, a method in which the zinc ingot 46 is gradually melted with the heat received from the molten zinc inside and outside of 450 ° C. is also taken.
In order to compensate for heat removal due to heat release to the atmosphere or dropping of a new zinc ingot 46, as described in Patent Document 2, as shown in FIG. 12, a heating device 47 that heats molten zinc in a compensatory manner. May be provided. The principle of the heating device 47 in that case is known to be based on induction heating, and as shown in FIG. 12C-C, two flow paths are provided around the induction heating coil 48 and suction is provided. This is a mechanism for selectively discharging the waste zinc and the discharging one, and heating the molten zinc sucked from the suction flow path by induction heating and then discharging it from the discharge flow path.

  Now, the hot dip galvanizing bath usually contains the Fe content that has melted out of the steel sheet and the Al content that is necessary for the plating quality. These Fe and Al compounds precipitate, become fine particles called dross (49), deposit on the bottom of the pot 40, and adhere to the steel strip S that is passed by being rolled up by the flow of these baths. May be a quality defect.

Incidentally, the heating device 47 that heats the molten zinc in a compensatory manner is often installed upward, and θ in FIG. 12 is set to be fixed in the range of 0 to 40 °.
Returning to the dropping of the zinc ingot 46, when the zinc ingot 46 having a considerable heat capacity is dropped into the molten zinc in the pot 40, the zinc ingot 46 is landed on the bottom of the pot 40. At that time, since the temperature of the molten zinc is locally reduced around the area and dross is likely to be generated, various methods have been proposed for the purpose of preventing or suppressing this.

  For example, in the above-mentioned Patent Document 1, as shown in FIG. 13, the zinc ingot is laid just below the zinc ingot dropping position and near the lower end of the molten zinc discharge port from the heating device 47 provided with the pot 40. A method of providing an ingot receiver 80 having a shape that can be supported in a heated state, partitioning the pot 40 with a weir or the like, and providing a region where the zinc ingot 46 is dropped, and controlling the temperature of the molten zinc in the region simultaneously. Proposed.

Further, Patent Document 3 proposes a method for suppressing a temperature drop of molten zinc by applying a flow in the vicinity of the immersed zinc ingot 46.
Furthermore, Patent Document 4 proposes a method for preventing the generation of dross 49 by dissolving and dropping the zinc ingot 46 above the pot.
And in patent document 5, the zinc ingot 46 dropping area | region and a plating area | region are made for the purpose of preventing the low temperature molten zinc generated at the time of zinc ingot 46 dropping | flowing into a plating area | region, reacting with Fe, and producing | generating dross. It has been proposed to provide a labyrinth-like flow path that separates and leads from the zinc ingot 46 dropping region to the plating region.

Finally, in Patent Document 6, as shown in FIG. 14, a zinc ingot 46 is grasped with a pair of claws, gradually lowered into a pot 40 filled with molten zinc and melted, and finally the bottom of the zinc ingot 46. A method of closing and supporting a pair of openable / closable support plates 491 has been proposed.
Japanese Patent No. 2643048 Japanese Patent Laid-Open No. 05-007880 JP 2000-144357 A JP 2001-254162 A JP 2002-212696 A JP-A-07-018394 Japanese Patent Application No. 2005-062276 (not disclosed at the time of filing this application)

If the zinc ingot is dropped to the bottom of the pot 40 filled with molten zinc, it becomes a low-temperature heat source, dross 49 is generated in the vicinity, and deposition on the bottom of the pot 40 is promoted.
Furthermore, since the specific gravity of molten zinc becomes larger as the temperature is lower, this also acts as an action of lowering the temperature of molten zinc, which causes the dross deposition to be further promoted. The dross deposited in this way is rolled up along with the flow of molten zinc in the pot 40 generated along with the passing of the steel strip S and dropping of the zinc ingot 46, and adheres to the metal strip to be plated. There is a problem that it may become a defect above.

  In the method of Patent Document 1 described above, the zinc ingot can be supported in a lying state immediately below the zinc ingot dropping position and in the vicinity of the lower end of the molten zinc discharge port from the heating device 47 attached to the pot 40. In addition, since the ingot receiver 80 (see FIG. 13) is provided, the generation of dross and the inflow of dross into the pot 40 are considerably suppressed, but there is room for slight improvement.

  Further, in the method as disclosed in Patent Document 3, although the flow is applied to the vicinity of the zinc ingot 46, the zinc ingot 46 is immersed in the molten zinc only at the lower portion, and the remaining zinc ingot 46 is melted in the molten zinc. Of course, a means for gripping outside is necessary, and when the portion of the zinc ingot 46 below the gripped portion is completely dissolved, the remaining portion of the zinc ingot 46 is dropped into the molten zinc in the pot 40. There is only. Then, since the remaining zinc ingot 46 lands on the bottom of the pot 40, it becomes a low-temperature heat source, and dross is generated in the vicinity.

In order to prevent this, it is necessary to set the range in which the molten zinc flows to two places: a height direction position in a state where the zinc ingot 46 is held and a height direction position in a state where the zinc ingot is landed, There is a problem that the apparatus becomes complicated and large-scale.
Further, in the method as disclosed in Patent Document 4, when the heating means heats and melts the portion of the zinc ingot 46 held by the nail that holds the zinc ingot 46, the remaining zinc ingot 46 is potted. Since it lands on the bottom of 40, it becomes a low-temperature heat source, and there is a problem similar to the above-mentioned Patent Document 3 in that dross is generated in the vicinity.

In the method as disclosed in Patent Document 5, the labyrinth-like flow path that separates the zinc ingot 46 dropping region and the plating region and communicates from the zinc ingot 46 dropping region to the plating region is provided, so that the apparatus is complicated and large. There is a problem of becoming a thing.
Finally, in the method as in Patent Document 6, it is difficult to control the speed of holding the zinc ingot 46 with a pair of claws, gradually lowering it into the pot 40 filled with molten zinc, and melting it. If the control device is included, there is still a problem that the device becomes complicated and large.

  The present invention relates to a hot dip galvanizing apparatus and a hot dip galvanized metal strip using the hot dip galvanizing apparatus that can suppress dross from being generated and deposited by dropping a zinc ingot into the hot dip zinc pot. It is an object to provide a method.

The present invention has been made to solve the above-described problems.
That is, the present invention is as follows.
(1) A hot dip galvanizing apparatus for immersing and plating a steel plate in a pot filled with hot dip zinc, immediately below the dropping position of the zinc ingot and above the upper end of the hot dip zinc discharge port of the heating device provided with the pot A hot dip galvanizing apparatus characterized in that an ingot receiver having a shape capable of supporting the lower end of the zinc ingot is provided at the position.

(2) The ingot receiver supports a part of a lower end of the zinc ingot, and a projected area of a part of the ingot on a horizontal plane is 35% or more with respect to a projected area of the zinc ingot on the horizontal plane. The hot dip galvanizing apparatus according to (1), characterized in that
(3) The hot dip galvanizing apparatus according to (1) or (2), wherein a partition wall is provided on a side of the zinc ingot when the lower end of the zinc ingot is supported by the ingot receiver. .

(4) The partition wall has a lower end positioned at a position 100 mm or more higher than a position corresponding to the lower end of the ingot, according to any one of (1) to (3). Hot dip galvanizing equipment.
(5) The hot dip galvanizing apparatus according to any one of (1) to (4), wherein a flat plate is provided further below the ingot receiver.

  (6) A method for producing a hot dip galvanized metal strip using the hot dip galvanizing apparatus according to any one of (1) to (5).

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress with a simple mechanism that dross generate | occur | produces and accumulates with the dropping of a zinc ingot to a molten zinc pot.

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of the embodiment of the hot dip galvanizing apparatus of the present invention (1).
Basically, the configuration of the conventional one shown in FIG. 12 is followed, but the hot dip galvanizing apparatus of the present invention of (1) melts the heating device 47 attached to the pot 40 immediately below the dropping position of the zinc ingot 46. An ingot receiver 80 having a shape capable of supporting the lower end of the zinc ingot 46 is provided at a position above the upper end of the zinc discharge port 471.

  The lower end of the zinc ingot 46 is supported at a position above the upper end of the molten zinc discharge port 471 because the flow caused by the convection generated by the influence of the molten zinc discharged from the heating device 47 is dropped. This is to prevent the occurrence of dross as much as possible by becoming a low-temperature heat source when the zinc ingot 46 at the initial stage of dropping is not sufficiently heated.

  As shown in FIG. 1 (a), as described in the above-mentioned Patent Document 1, (i) even when the zinc ingot 46 is dropped in its original shape and supported on the ingot receiver 80 in a laid state. Alternatively, as shown in FIG. 1 (b), (ii) the zinc ingot 46 is immersed in the molten zinc only at the lower part (instead of being gradually immersed as in Patent Document 6, there is simply The lower part of the zinc ingot 46 is soaked by a certain height), the remaining zinc ingot 46 is gripped outside the molten zinc, and the part of the zinc ingot 46 below the gripped part is completely dissolved. Thus, even when the remaining zinc ingot 46 is dropped on the molten zinc in the pot 40 and supported on the ingot receiver 80 in a standing state, it is positioned above the upper end of the molten zinc discharge port 471. , Zinc By supporting the lower end of the got 46, the zinc ingot 46 dropped and the molten zinc around it are in a high-temperature state because they are heated by hot zinc that is discharged from the heating device 47 and is hotter than the surroundings. And dross generation can be suppressed.

  Considering the case below the lower end of the zinc ingot 46, for example, if it is less than 100 mm below the lower end of the molten zinc discharge port 471, no matter how the dimension of the zinc ingot 46 is adjusted, the above-mentioned (i) If this is the case, as shown in FIG. 2 (a), and in the case of (ii) above, as shown in FIG. 2 (b), the molten zinc discharged from the heating device 47 The flow by the convection generated by the influence is hindered by the dropped zinc ingot 46. Therefore, it becomes difficult for the heated molten zinc to reach the entire pot 40, and dross is likely to occur in the locally low temperature molten zinc portion in the pot 40.

  In FIG. 2, an arrow indicated by a solid line in the molten zinc in the pot 40 indicates a rough flow when the flow direction of the molten zinc discharged from the heating device 47 is θ = 40 ° with respect to the horizontal direction. The arrows indicated by dotted lines indicate the flow direction when the direction of the flow due to the convection generated by the influence of the molten zinc discharged from the heating device 47 is horizontal, that is, θ = 0 °. This is a rough outline. Both show that the flow of convection generated by the influence of the molten zinc discharged from the heating device 47 is obstructed by the dropped zinc ingot 46.

Further, when the position to support the lower end of the zinc ingot 46 is lowered downward from the lower end of the molten zinc discharge port 471 of the heating device 47 and beyond 500 mm, the zinc ingot 46 approaches the bottom of the pot 40, It becomes a low-temperature heat source, and dross is generated in the vicinity.
Then, if the position to support the lower end of the zinc ingot 46 is set to a position below 100 mm to 500 mm from the lower end of the molten zinc discharge port 471 of the heating device 47, primarily, The generation of dross can be suppressed, and the inventors proposed the invention in Patent Document 7.

However, as another method, it is also effective for the inventors to place the position where the lower end of the zinc ingot 46 is supported above the upper end of the molten zinc discharge port 471 of the heating device 47. The present invention has been found and the present invention has been conceived.
As shown in FIG. 3, in the molten zinc in the pot 40, an arrow indicated by a solid line indicates that the flow direction by convection generated by the influence of the molten zinc discharged from the heating device 47 is θ = The outline of the flow in the case of 40 ° is shown. The arrow indicated by a dotted line indicates that the flow direction by convection generated by the influence of the molten zinc discharged from the heating device 47 is in the horizontal direction, that is, θ. This shows the general flow in the case of = 0 °.

In the case of θ = 40 °, the zinc ingot 46 is heated by molten zinc that is discharged from the heating device 47 and indicated by a solid line at a temperature higher than that of the surroundings. Is maintained at a high temperature, and dross generation can be suppressed.
Also in the case of θ = 0 °, the zinc ingot 46 is discharged from the heating device 47, reaches the outer wall of the pot 40 on the opposite side where the heating device 47 is present, and returns to the surroundings, indicated by a broken line. In comparison, since it is heated by high-temperature molten zinc, the dropped zinc ingot 46 and its surrounding molten zinc are maintained in a high-temperature state, and dross generation can be suppressed.

  Even when θ is an intermediate value between 0 ° and 40 °, both of the above-described actions are partially received, so the dropped zinc ingot 46 and the surrounding molten zinc are maintained at a high temperature, and dross is generated. Can be suppressed.

Example 1 (related to claim 1 of the present invention):
FIG. 4 shows experimental results when the hot dip galvanizing apparatus of the type shown in FIG. 1A (example of the present invention) and the case without the ingot receiver 80 (comparative example) are operated.
The position where the lower end of the zinc ingot 46 of the present invention is supported is 10 mm above the upper end of the molten zinc discharge port 471 of the heating device 47 (the position at which the lower end of the zinc ingot 46 is supported is 60 mm). In both the inventive example and the comparative example, 200 zinc ingots 46 were dropped, and the amount of dross deposited (height from the bottom of the pot 40) when the hot dip galvanizing operation of the steel strip was performed for one week (7 days) In the case of the example of the present invention, it can be seen that the accumulation of dross 49 can be significantly suppressed compared to 100 mm and 200 mm in the case of the comparative example.

Incidentally, other conditions and results are as described below.
The average temperature of the molten zinc in the pot 40 is 460 ° C., the temperature of the molten zinc at a height of 50 mm from the bottom of the pot 40 is 458 ° C., the average temperature above the induction heating device 47 is 462 ° C. When 80 was projected on a horizontal plane, it was 800 mm × 800 mm and there was no void.

The direction of flow by convection generated by the influence of molten zinc discharged from the heating device 47 was set to θ = 20 ° with respect to the horizontal direction.
The external dimensions of the zinc ingot 46 are 1200 mmH × 400 mmW × 300 mmD, and the recess is held by a nail and immersed in molten zinc. When the portion immersed in the molten zinc of the zinc ingot 46 melts and the height dimension reaches 100 mm, the nail is immediately above the molten zinc bath surface, so the nail is released here to drop the zinc ingot 46 And received it once with the ingot receiver 80. Thereafter, the temperature of the molten zinc having a height of 50 mm from the bottom of the pot 40 decreased to 456 ° C., but once recovered to 457.5 ° C. as the temperature of the zinc ingot 46 increased.

After this, when the zinc ingots 46 were repeatedly dropped and operated, dross 49 was deposited on the bottom of the pot 40 to a height of 100 mm per week even after one week after dropping 200 zinc ingots 46. Dross 49 was deposited on the receptacle 80 to a height of 10 mm. At one week, the dross attached to the steel sheet was 1 piece / m ² or less.
When there is no ingot receiver 80 (comparative example), the zinc ingot 46 lands on the bottom of the pot. At this time, the temperature of the molten zinc at a height of 50 mm from the bottom of the pot decreases to 453 ° C. did. This recovered to 456 ° C. along with the dissolution of the zinc ingot 46, but as a result of starting to immerse the next zinc ingot 46 for supplying zinc necessary for plating, the temperature decreased again to 453 ° C. After this, the zinc ingots 46 were repeatedly dropped and operated, and after one week after dropping 200 zinc ingots 46, the height of the dross 49 deposited on the bottom of the pot 40 was examined to be 150 mm. Also, dross adhesion to the steel plate was 20 pieces / m ² with a diameter of 0.2 mm or more, which was much more than when there was an ingot receiver 80.

Here, the story changes, how to use the hot dip galvanizing apparatus of the present invention, and how the hot dip galvanizing apparatus of the present invention can solve the above-mentioned problems. explain.
As described in Patent Document 1,
(I) A normal temperature zinc ingot 46 is dropped into the pot 40, and the zinc ingot 46 is placed immediately below the zinc ingot 46 dropping position and in the vicinity of the upper end of the molten zinc discharge port from the heating device 47 attached to the pot 40. An ingot receiver 80 having a shape that can be supported in the state of being put on is provided, and the zinc ingot 46 is gradually dissolved by heat received from molten zinc inside and outside 450 ° C. (FIG. 1A), or Patent Document 3 As described in 4,
(Ii) The zinc ingot 46 is immersed only in the lower part of the molten zinc, and the remaining zinc ingot 46 is gripped outside the molten zinc, and the portion of the zinc ingot 46 below the gripped part is completely dissolved. Then, the remaining zinc ingot 46 is dropped on the molten zinc in the pot 40 and stood on the ingot receiver 80. With the heat received from the molten zinc inside and outside 450 ° C., the zinc ingot 46 gradually Is dissolved (FIG. 1B).

Up to this point, there is a part in common with conventional patent documents 1, 3, 4, and the like.
Even if the hot dip galvanizing apparatus of the present invention holds the zinc ingot 46 using claws and dissolves in the pot 40 filled with molten zinc as in Patent Document 4, the claws are opened. When the zinc ingot 46 is dropped, it does not reach the bottom of the pot 40 and is supported by the ingot receiver 80. Thereby, the temperature fall of molten zinc near the bottom of the pot 40 and generation | occurrence | production of dross can be suppressed.

Since the hot dip galvanizing apparatus of the present invention does not take the temperature drop suppression means of the hot dip due to the positive flow as in Patent Document 3, the hot dip galvanization near the zinc ingot 46 on the ingot receiver 80 is as follows. Although the temperature drop is unavoidable, the temperature drop of the molten zinc in the entire pot 40 is suppressed by the convection and heat diffusion inevitably generated in the pot 40, and the zinc ingot 46 is landed directly on the bottom of the pot 40. as compared with the case where the, occurrence of dross 49 is also reduced. Further, since the generated dross 49 may be diffused and redissolved before being deposited, the possibility of adversely affecting the quality of the metal plate to be plated is reduced.

Example 2 (related to claim 2 of the present invention):
By the way, the ingot receiver 80 may have a flat plate shape, but may be provided with holes (voids). This is to promote the flow of molten zinc by convection in the pot 40. Some examples of the shape in which the ingot receiver 80 is projected onto the horizontal plane are shown in FIG. 5, but shapes other than the examples given here may be used.

In the hot dip galvanizing apparatus of the present invention (2), the ingot receiver 80 supports a part of the lower end of the zinc ingot 46, and the projected area of the part on the horizontal plane is the horizontal plane of the zinc ingot. It occupies 35% or more of the projected area.
Even if an ingot receiver 80 of the type shown in any of (a), (b), (c), and (d) in FIG. 5 is used, a part of the projected area onto the horizontal plane that supports a part of the lower end of the zinc ingot 46 However, if the ratio α of the zinc ingot to the projected area on the horizontal plane is less than 35%, the zinc ingot 46 will slip through the gap and land on the bottom of the pot 40 before it completely melts. As a result, as shown in FIG. 6, the dross accumulation amount (height from the bottom of the pot 40) tends to slightly increase when the hot dip galvanizing operation of the steel strip is performed for one week (7 days).

As an example, except for providing a gap in the ingot receiver 80, the porosity is 44% without changing the overall size when the ingot receiver 80 is projected onto a horizontal plane under the same conditions as in the first embodiment. As a result, one week after dropping 200 zinc ingots 46, the height of the dross 49 deposited on the bottom of the pot 40 was examined and found to be 90 mm. In addition, the number of dross attached to the steel sheet also decreased to 0.6 / m ² .

  The zinc ingot 46 that has become small enough to pass through the gap is inevitably landed on the bottom of the pot 40, but the temperature rises while being supported by the ingot receiver 80, so α is 35%. If it falls below, the amount of dross deposited tends to increase slightly, but the action of generating dross 49 when landing on the bottom of the pot 40 can be reduced to some extent, and dross generation and accumulation are suppressed. The effect of the present invention is obtained.

Example 3 (related to claim 3 of the present invention):
Further, as in the present invention of (3), the ingot receiver 80 may be provided with a partition wall 81 on the side of the zinc ingot 46 when the lower end of the zinc ingot 46 is supported. This partition wall 81, particularly as in the type of FIG. 1A, (i) when dropping the zinc ingot 46 in its original shape and supporting it in a state of being laid on the ingot receiver 80, Since the dropped zinc ingot 46 has to be blocked, it may be completely tightly integrated with the ingot receiver 80, but as shown in FIG. You may install separately from the ingot receptacle 80. As long as the dropped zinc ingot 46 can be blocked, as in the type of FIG. 1 (a), (i) the zinc ingot 46 is dropped in its original shape and laid on the ingot receiver 80. Even if it is supported, it may of course be installed separately from the ingot receiver 80.

As an example, when a partition wall 81 as shown in FIG. 7 is provided under the same conditions as in Example 1 except that a gap is provided in the ingot receiver 80, the porosity is reduced to 25%. However, one week after dropping 200 zinc ingots 46, the accumulated height of the dross 49 at the bottom of the pot 40 was examined, and it was suppressed to 100 mm (FIG. 10). The number of dross attached to the steel sheet was also 0.6 / m ² . This is presumably due to the smooth flow of molten zinc.

In the present invention, the upper end of the partition wall 81 is connected unlike the one in Patent Document 1. Thereby, molten zinc can come and go between the area immediately below the dropping position of the zinc ingot 46 and the other area.
Example 4 (related to claim 4 of the present invention):
Further, as in the present invention of (4), the partition wall 81 is installed separately from the ingot receiver 80, and the partition wall 81 is 100 mm from the position corresponding to the lower end of the zinc ingot 46 as shown in FIG. As mentioned above, it is preferable that the lower end is located in the upper position.

As an example, a partition wall 81 as shown in FIG. 8 is provided under the same conditions as in Example 1 except that a gap is provided in the ingot receiver 80, and the partition wall 81 corresponds to the lower end of the zinc ingot 46. Assuming that the lower end is located at a position 100 mm above the position where the bottom of the pot 40 is dropped, one week after dropping 200 zinc ingots 46, even when the porosity is lowered to 25%. When the deposition height of the dross 49 was examined, it was suppressed to 90 mm (FIG. 10). The number of dross attached to the steel sheet was also 0.6 / m ² .

Example 5 (related to claim 5 of the present invention):
Alternatively, as another form, as shown in FIG. 9, a flat plate 82 may be provided further below the ingot receiver 80. When the zinc ingot 46 in the initial stage of dropping is not yet sufficiently heated, it becomes a low-temperature heat source, dross may be generated, and dross may accumulate on the ingot receiver 80. The type shown in FIG. (I) When the zinc ingot 46 is dropped in its original shape, dross falls from the gap due to the impact, floats in the molten zinc, and is trapped. It can suppress that it adheres to the steel strip S and becomes a quality defect.

Example 6 (related to claim 6 of the present invention):
Even if it is a hot dip galvanizing apparatus of any form of the above Examples 1 to 5, if it is applied as a pot 40 in a continuous hot dip galvanizing line 100 of a steel strip as shown in FIG. It can suppress effectively that it adheres to the steel strip S and becomes a defect on quality.
The same can be said not only for continuous hot-dip galvanizing of steel strips but also for hot-dip galvanizing of metal strips of any material.

It is a figure which shows one embodiment of this invention. It is a figure which shows an example different from this invention. It is a figure which shows the effect | action of this invention. It is a figure which shows the effect of this invention. It is a figure which shows the example of the shape which projected the ingot receptacle used for this invention on the horizontal surface. It is a figure which shows the difference in an effect by the difference in the shape which projected the ingot receptacle used for this invention on the horizontal surface. It is a figure which shows another embodiment of this invention. It is a figure which shows another embodiment of this invention. It is a figure which shows another embodiment of this invention. It is a figure which shows the difference in an effect by the difference in embodiment of this invention. It is a figure which shows a prior art. It is a figure which shows a prior art. It is a figure which shows a prior art. It is a figure which shows a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Payoff reel 20 Welding machine 30 Heating zone 40 Pot 41 Snout 42 Sink roll 43 Warp correction roll 44 Gas wiping device 45 Wiping roll 46 Zinc ingot 47 Heating device 471 Molten zinc discharge port 48 Induction heating coil 49 Dross 491 Support plate 50 Tension Reel 60 Cutting machine 70 Alloying furnace 80 Ingot receiver 81 Partition wall 82 Flat plate 100 Continuous hot-dip galvanizing line S Steel strip G Gas

Claims (6)

  A hot dip galvanizing apparatus for immersing and plating a steel plate in a pot filled with molten zinc, immediately below the dropping position of the zinc ingot and above the upper end of the molten zinc discharge port of the heating apparatus provided with the pot. A hot dip galvanizing apparatus comprising an ingot receiver having a shape capable of supporting the lower end of the zinc ingot.   The ingot receiver supports a part of the lower end of the zinc ingot, and the projected area of a part of the zinc ingot occupies 35% or more of the projected area of the zinc ingot onto the horizontal plane. The hot dip galvanizing apparatus according to claim 1.   The hot dip galvanizing apparatus according to claim 1 or 2, wherein a partition wall is provided on a side of the zinc ingot when the lower end of the zinc ingot is supported by the ingot receiver.   The hot dip galvanizing apparatus according to any one of claims 1 to 3, wherein the partition wall has a lower end positioned at a position 100 mm or more higher than a position corresponding to the lower end of the ingot. .   The hot dip galvanizing apparatus according to any one of claims 1 to 4, wherein a flat plate is provided further below the ingot receiver.   The manufacturing method of the hot dip galvanized metal strip using the hot dip galvanizing apparatus in any one of Claims 1 thru | or 5.

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