Technical field
[0001]
The present invention relates to a method continuous molten metal plating apparatus and a continuous molten metal plating.
BACKGROUND
[0002]
Continuous molten metal plating apparatus is an apparatus for plating a metal strip represented by a steel strip with molten metal such as zinc. The continuous molten metal plating apparatus comprises a roll which is disposed in the plating bath which stores the molten metal, and the sink roll for changing the conveying direction of the metal strip, a pair of support rolls for flat correct the shape of the metal strip . Metal strip is introduced toward the oblique direction in the plating bath, after being changed in the conveying direction in the vertically upward by the sink roll, is pulled out of the plating bath through while being sandwiched between a pair of support rolls . Then, the gas wiping nozzles disposed on both sides of the metal strip on the surface of the metal strip by blowing gas, by scraping the excess molten metal drawn up adhering to the surface of the metal strip, coating weight of the molten metal (hereinafter, also referred to as "basis weight".) is adjusted.
[0003]
　If correction of the shape of the metal strip by a support roll is inadequate, the metal strip after passing through the support rolls, warpage may occur in the plate width direction. In such a case, variation in the distance between the gas wiping nozzle and the metal strip in the plate width direction of the metal strip occurs, the collision pressure of the gas to the metal strip becomes uneven in the sheet width direction. Thus, the basis weight may become uneven. To prevent the basis weight of such a continuous molten metal plating becomes non-uniform, technology relating to the correction of the shape of the metal strip has been proposed by the support rolls.
[0004]
　For example, Patent Document 1, the molten metal plating bath to obtain hot dip plated steel sheet having excellent uniformity of the coating weight of non-uniformity of both the thickness direction and the longitudinal direction of the plated steel strip simultaneously resolved coating weight to provide a medium roll apparatus inexpensively, at least the support rolls positioned immediately above the sink roll and undriven roll, together to at least one of the control positions in the horizontal direction of the sink roll and support roll technique There has been disclosed.
CITATION
Patent Document
[0005]
Patent Document 1: Laid-Open Publication No. 6-128711
Summary of the Invention
Problems that the Invention is to Solve
[0006]
　However, in the conventional continuous molten metal plating, at the contact portion between the support roll of metal strip, there is a case where flaws of the surface of the metal strip is produced. For example, when a steel strip is used as the metal strip, due to the dross which is an intermetallic compound is generated in the plating bath, scratches on the surface of the plated steel strip can occur. Specifically, and roll flaws due to the dross adhering to the support roll is transferred to the steel strip, it is dross flaw entrained dross adheres to the steel strip between the strip and the support rolls can occur. Further, in some cases scratches are caused by the support roll from slipping. Therefore, from the viewpoint of improving the quality of the plated steel strip, in addition to improving the uniformity of the basis weight, it is desirable to suppress the occurrence of scratches on the surface of these plated steel strip.
[0007]
　The present invention has been made in view of the above problems, it is an object of the present invention, by suppressing the generation of scratches on the surface of the plated steel strip, to improve the quality of the plated steel strip capable to provide a novel and improved method continuous molten metal plating apparatus and a continuous molten metal plating.
Means for Solving the Problems
[0008]
　In order to solve the above problems, according to an aspect of the present invention, provided in the plating bath, a sink roll for changing the conveyance direction of the steel strip upwardly within the plating bath, above said sink roll position, and a first support roll in contact with the surface of the steel strip in contact with the sink roll, within the plating bath, positioned above said first support roll, the surface of the steel strip in contact with the sink roll and the second support roll in contact with the opposite surface, wherein the first support roll diameter, the diameter of the second support roll and said the rotational axis of the first support roll second support rolls distance of vertical direction between the rotation axis, satisfies the condition of formula (4) from the following equation (1), a continuous molten metal plating apparatus is provided.
[0009]
[Number 1]

However,
D1: the first support roll diameter (mm)
D2: the second support roll diameter (mm) L:
wherein the rotation axis of the first support roll second support rolls distance of vertical direction between the rotation axis (mm).
[0010]
　May comprise an adjustable adjusting unit in the vertical position of said first support roll.
[0011]
　In order to solve the above problems, according to another aspect of the present invention, the sink roll provided in the plating bath, the step of changing the conveying direction of the steel strip upwardly within the plating bath, the located from sink roll upwards, the a first support roll in contact with the surface of the steel strip in contact with the sink roll, within the plating bath, positioned above said first support roll, contact with the sink roll anda step of passing the steel strip while being sandwiched between the second support roll in contact with the surface opposite to the surface of the steel strip, the first support roll diameter, the second support rolls the diameter and vertical distance between the rotation axis of the first support and the second support roll and the rotation axis of the roll, the following equation (1) so as to satisfy the condition of equation (4), the first Comprising the step of preliminarily adjusting the vertical position of the port roles, the method continuous molten metal plating is provided.
[0012]
[Number 2]

However,
D1: the first support roll diameter (mm)
D2: the second support roll diameter (mm) L:
wherein the rotation axis of the first support roll second support rolls distance of vertical direction between the rotation axis (mm).
[0013]
　According to the present invention described above, by suppressing the generation of scratches on the surface of the plated steel strip, it is possible to improve the quality of the plated steel strip.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
FIG. 1 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus according to an embodiment of the present invention.
[2] The diameter of the first support roll according to the embodiment D1, the vertical distance between the axes of rotation of the second support roll diameter D2 and the first support roll and the second support roll it is an explanatory view for explaining a relationship of L.
A first support roll according to FIG. 3 the same embodiment is a schematic diagram for explaining the contact avoidance conditions with the sink roll.
4 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus according to the first embodiment.
5 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus according to the second embodiment.
6 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus according to a third embodiment.
7 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus according to a fourth embodiment.
It is a schematic diagram illustrating an example of a schematic configuration of FIG. 8 continuous molten metal plating apparatus according to an application example.
9 is an explanatory view for explaining various set values in Examples and Comparative Examples.
FIG. 10 is an explanatory view for explaining various set values in Examples and Comparative Examples.
DESCRIPTION OF THE INVENTION
[0015]
　Reference will now be described in detail preferred embodiments of the present invention. In the specification and the drawings, components having substantially the same function and structure are a repeated explanation thereof by referring to the figures.
[0016]
　<1. Construction of a continuous molten metal plating apparatus>
　First, with reference to FIG. 1, the configuration of the continuous molten metal plating apparatus 1 according to an embodiment of the present invention. Figure 1 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus 1 according to this embodiment.
[0017]
　As shown in FIG. 1, a continuous molten metal plating apparatus 1, the steel strip 2, by immersion in a plating bath 3 filled with molten metal, after the molten metal on the surface of the steel strip 2 is continuously adhered a device for the molten metal to a predetermined basis weight. Continuous molten metal plating apparatus 1 is provided with a plating tank 4, a snout 5, a sink roll 6, a first support roll 7, a second support roll 8, the gas wiping nozzle 9, a.
[0018]
　Strip 2 is a metal strip to be to be subjected to plating by molten metal. As the molten metal constituting the plating bath 3, for example, Zn, Al, Sn, alone or an alloy of Pb and the like. Alternatively, the molten metal is to these metals or alloys, for example Si, nonmetallic element such as P, Ca, Mg, typical metal elements or Sr, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, etc. also include those containing a transition metal element. In the following description, the molten zinc is used as the molten metal forming the plating bath 3, by adhering molten zinc on the surface of the steel strip 2, an example of manufacturing a galvanized steel sheet.
[0019]
　Plating tank 4 for storing the plating bath 3 consisting of the molten metal. Snout 5, the upper end is connected for example to the outlet side of the annealing furnace, the lower end is provided to be inclined by immersing in the plating bath 3. Sink roll 6 is arranged below in the plating bath 3. Sink roll 6 has a greater diameter than the first support roll 7 and the second support roll 8. Sink roll 6, with the conveyance of the steel strip 2 rotates clockwise shown, the conveyance direction of the steel strip 2 introduced obliquely downward in the plating bath 3 through the snout 5, vertically above change to be. Sink roll 6 may be a non-driving roll.
[0020]
　The first support roll 7 and the second support roll 8 is arranged from the sink roll 6 upward in the plating bath 3. The first support roll 7 is located above the sink roll 6 in the plating bath 3, in contact with the steel strip 2 of the surface in contact with the sink roll 6. The second support roll 8 is positioned above the first support roll 7 in the plating bath 3, in contact with the surface opposite to the surface strip 2 in contact with the sink roll 6. Diverted by the sink roll 6, vertically upwardly lifted steel strip 2 passes while being sandwiched between the first support roll 7 and the second support roll 8. The first support roll 7 may be a non-driven roll. The second support roll 8 may be a non-drive roll or drive roll.
　The depth of the plating bath 3 is usually more than 2000 mm, it is less 3000 mm. The depth of the plating bath 3, more deeply may be, but if more deeply, difficult to work pumping of dross deposited in the bath bottom, the bath in the temperature distribution is increased, dross generated issues such as is likely to occur. The diameter D3 of the sink roll 6, generally at 600mm or more, are 800mm or less.
[0021]
　By setting the horizontal position of the first support roll 7 with respect to the second support roll 8 as appropriate, the steel strip 2 passing while being sandwiched between the first support roll 7 and the second support roll 8 by pushing the horizontal, warp in the width direction of the steel strip 2 is corrected. Thereby, it is possible to equalize the mass per unit area. Specifically, the push amount P1 illustrated in FIG. 1 for location in contact with the steel strip 2 is a horizontal direction of the relative distance of a portion in contact with the steel strip 2 of a first support roll 7 of the second support roll 8, steel It is appropriately set to a value such that the shape of the strip 2 may suitably corrected. Specifically, the pressing amount P1 is, 5 mm or more, may be set to 30mm or less. The first support roll 7 and the second support roll 8 has a function of suppressing vibration of the steel strip 2 to be lifted. Vibration generated in the steel strip 2 passing through the second support roll 8 may also be a factor for the basis weight uneven. Thus, by suppressing the generation of vibration of the steel strip 2 to be pulled up, it is possible to equalize the mass per unit area.
[0022]
　Gas wiping nozzle 9, in order to adjust the basis weight of the molten metal to the steel strip 2, for injecting gas such as air or nitrogen gas is sprayed on the surface of the steel strip 2. The gas wiping nozzle 9, a high-pressure gas compressed by a compressor (not shown) or the like is introduced. Gas wiping nozzles 9 are arranged on both sides in the thickness direction of the steel strip 2 above the first support roll 7 and the second support roll 8, the position of a predetermined height from the bath surface of the plating bath 3 It is disposed. Injected gas from such a gas wiping nozzle 9 is sprayed onto the both surfaces of the steel strip 2, which is pulled up from the plating bath 3 vertically upward, the excess molten metal is scraped off. Thus, the basis weight of the molten metal to the surface of the steel strip 2 is adjusted to a proper amount, the film thickness of the molten metal film is adjusted.
[0023]
　It is described continuous operation of the molten metal plating apparatus 1 having the above configuration. Continuous molten metal plating apparatus 1, the steel strip 2 is moved by a drive source (not shown), thereby the sheet passing the respective sections in the apparatus. Strip 2 according is introduced obliquely downward in the plating bath 3 through the snout 5, orbiting the sink roll 6, the conveying direction is changed upward in the vertical direction. Then, the steel strip 2 includes a first support roll 7 sandwiched rises through while between the second support roll 8, pulled 3 outside the plating bath. Thereafter, the pressure of the gas blown from the gas wiping nozzle 9, is scraped off excess molten metal adhering to the steel strip 2, adjusting the amount of deposition of the molten metal to the surface of the steel strip 2 to a predetermined weight per unit area It is. As described above, the continuous molten metal plating apparatus 1, the steel strip 2 in the plating bath 3 is continuously immersed, by plating molten metal, to produce a molten metal plated steel sheet having a predetermined basis weight . Incidentally, the sheet passing speed of the steel strip 2, 60 m / min or more, is set to 180 m / less.
[0024]
　As described above, in the conventional continuous molten metal plating and may scratches, roll flaws and flaws on the surface of the plated steel strip of dross defects such as occur. In continuous molten metal plating apparatus 1 according to the present embodiment, the first support diameter D1 of the roll 7, the second diameter D2 and the first support roll 8 of the support roll 7 of the rotary shaft and the second support roll 8 by the distance L in the vertical direction of the rotation axis is set so as to satisfy the specific conditions described later, it is possible to suppress the occurrence of scratches on the surface of the plated steel strip. Thereby, it becomes possible to improve the quality of the plated steel strip. The distance L is specifically may be set to at least 160 mm. Preferably, the distance L is more than 175mm, or less 275 mm.
[0025]
　<2. The first support roll diameter and the second support roll diameter settings>
　Next, with reference to FIGS. 2-7, in a continuous molten metal plating apparatus 1 according to this embodiment, first support roll 7 describing the rotation axis and corresponding to the vertical distance L between the rotation axis of the second support roll 8, for setting the diameter D2 of the diameter D1 and the second support roll 8 of the first support roll 7.
[0026]
　In continuous molten metal plating apparatus 1 according to the present embodiment, the first support diameter D1 of the roll 7, the second diameter D2 and the first support roll 8 of the support roll 7 of the rotary shaft and the second support roll 8 distance L in the vertical direction of the rotation axis is set so as to satisfy the condition of equation (4) from the following equation (1).
　Here, the diameter D1 of the first support roll 7, the diameter D2 of the second support roll 8, and, the vertical distance between the axes of rotation of the first support roll 7 and the second support roll 8 L is set in units of all (mm).
[0027]
[Number 3]

[0028]
　Here, organized by substituting D of formula (1) into equation (2), the following equation (5) and (6) is derived.
[0029]
[Formula 4]

[0030]
　Moreover, when organizing the formula (4), the following equation (7) is derived.
[0031]
[Formula 5]

[0032]
　2, the diameter D1 of the first support roll 7 according to the present embodiment, the rotation shaft of a diameter D2 and the first support roll 7 of the second support roll 8 and the rotating shaft of the second support roll 8 it is an explanatory view for explaining a relationship of the vertical distance L. In Figure 2, the formula (3) in the D1-D2 plane, equation (5), (6) and the boundary line B4 from the boundary line B1 indicating the range of the area defined by each of formula (7) is shown there. Incidentally, represented by the formula (11) each border B4 from the boundary line B1 from the following equation (8).
[0033]
[Number 6]

[0034]
　As shown in FIG. 2, region E1 surrounded by the boundary line B4 from the boundary line B1 in D1-D2 plane is a region indicating a setting value of the diameter D1 and diameter D2 that may be set according to the distance L. In continuous molten metal plating apparatus 1 according to the present embodiment, the diameter D1 and diameter D2 is set within the range of the region E1 shown in FIG.
[0035]
　As shown in equation (3), the diameter D1 of the first support roll 7 is set to 210mm or more for the score mark prevention. The diameter D1 of the first support roll 7, preferably more than 220 mm, it is 250mm or less.
　The diameter D1 of the first support roll 7, the diameter D2 of the second support roll 8 is too large, large push amount P1 of the first support roll 7 for C warp correcting is by dross transfer because roll flaws increases, defining the upper limit of the diameter D2 of the second support roll 8 as shown in equation (5).
　The diameter D1 of the first support roll 7, the diameter D2 of the second support roll 8 is too small, the dross is easily caught, since the dross defects increases, the lower limit of the diameter of the second support roll 8 was defined as equation (6).
[0036]
　Next, the formula (7) is derived as follows.
　And the lower end of the sink roll 6, the vertical distance of the upper end of the second support roll 8, to prevent dross defects caused by the dross at the bottom of the plating bath 3 is preferably set to 1500mm or less.
　That is, as shown in FIG. 1, the diameter D1 of the first support roll 7, the diameter D2 of the second support roll 8, sink diameter D3 of the roll 6, the rotation shaft and the second support of the first support roll 7 vertical distance L between the rotation axis of the roll 8, and the upper end and the distance L between the vertical direction of the roll with the lower end of the first support roll 7 of the sink roll 6 0 , it satisfies the condition required of formula (12) is there.
[0037]
[Number 7]

[0038]
　By transforming equation (12), so that equation (13).
[0039]
[Number 8]

[0040]
　Next, as shown in FIG. 3, the conditions sink roll 6 and the first support roll 7 are in contact is indicated by the condition of the expression (14).
[0041]
[Number 9]

[0042]
　To summarize the both sides of the equation (14), so that equation (15).
[0043]
[Formula 10]

[0044]
　Here, when the sink roll 6 and the first support roll 7 is too close, the steel strip 2, the circulating flow is generated in the region surrounded by the sink roll 6 and the first support roll 7, dross accumulation, growth It tends to. Therefore, the sink roll 6, the first support roll 7, it is necessary to secure a certain distance. The present inventors have found, as a result of investigation under various conditions, in order to prevent the dross defects, based on the equation (15) as a contact condition, the roll distance L in the vertical direction 0 to secure further more 200mm and it was confirmed that is preferable. Thus, the upper end of the sink roll 6, the roll distance L0 between the first support roll 7 should satisfy the equation (16).
[0045]
[Number 11]

[0046]
　In equation (12), the minimum distance between the rolls L satisfying formula (16) 0 Substituting, the following equation (17).
[0047]
[Number 12]

[0048]
　From equation (17), the diameter D2 of the second support roll 8, the range of formula (18).
[0049]
[Formula 13]

[0050]
　Maximum diameter D3 of the sink roll 6, since it is 800 mm, the diameter D2 of the second support roll 8 to the maximum diameter of the sink roll 6 is a range of the formula (19). As can be seen from equation (18), the smaller the diameter D3 of the sink roll 6, the range of possible diameter D2 of the second support roll 8 increases.
[0051]
[Number 14]

[0052]
　Hereinafter, Equation (3) defining the range of the region E1, the formula (5) will be described with reference to each of the reference example differs from the present embodiment the significance of formula (6) and (7).
[0053]
　Figure 4 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus 100 according to the first embodiment. Diameter D102 diameter D101 and the second support roll 108 of the first support roll 107 in a continuous molten metal plating apparatus 100 is set to a value that does not satisfy equation (3). In other words, in the first reference example, the diameter D102 of the first diameter of the support rolls 107 D101 and the second support roll 108, within the left area from the boundary line B1 in D1-D2 plane shown in FIG. 2 It is set to the value.
[0054]
　As shown in FIG. 4, in the first reference example, as compared to continuous molten metal plating apparatus 1 according to this embodiment shown in FIG. 1, the diameter D101 of the first support roll 107 is small. As the diameter D101 of the first support roll 107 is small, the contact area of ​​the first support roll 107 and the steel strip 2 is reduced. Thus, the rotational torque applied to the first support roll 107 is reduced. Thus, there is a case where poor rotation of the first support roll 107 occurs. Therefore, scratches may occur on the steel strip 2.
[0055]
　Figure 5 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus 200 according to the second embodiment. Diameter D202 diameter D201 and the second support roll 208 of the first support roll 207 in a continuous molten metal plating apparatus 200 is set to a value that does not satisfy equation (5). In other words, in the second reference example, the diameter D202 of the first diameter of the support rolls 207 D201 and the second support roll 208 is in the range of region above the boundary line B2 in D1-D2 plane shown in FIG. 2 It is set to the value.
[0056]
　As shown in FIG. 5, in the second reference example, as compared to continuous molten metal plating apparatus 1 according to this embodiment shown in FIG. 1, a larger diameter D202 of the second support rolls 208. The larger the diameter D202 of the second support roll 208, the effect of correcting the width direction of the warp of the steel strip 2 is reduced, it is necessary to move the first support roll 207 to the second support roll 208 side occur. Thus, in the second reference example, as compared to continuous molten metal plating apparatus 1 according to this embodiment shown in FIG. 1, the push amount P200 is large. Thereby, roll defects due to dross adhering to the first support roll 207 or the second support roll 208 is transferred to the steel strip 2 may occur.
[0057]
　Figure 6 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus 300 according to the third embodiment. The diameter D301 and the diameter D302 of the second support rolls 308 of the first support roll 307 in a continuous molten metal plating apparatus 300 is set to a value that does not satisfy equation (6). In other words, in the third reference example, the diameter D302 of the first diameter D301 and the second support roll 307 of the support roll 308, the scope of the region below the boundary line B3 in D1-D2 plane shown in FIG. 2 It is set to a value of the inner.
[0058]
　As shown in FIG. 6, in the third reference example, as compared to continuous molten metal plating apparatus 1 according to this embodiment shown in FIG. 1, the diameter D302 of the second support roll 308 is small. As the diameter D302 of the second support roll 308 is small, the effect of correcting the width direction of the warp of the steel strip 2 is increased, moves the first support roll 307 to the second support roll 308 on the opposite side need arises. Thus, in the third reference example, as compared to continuous molten metal plating apparatus 1 according to this embodiment shown in FIG. 1, a small pushing amount P300. Thus, dross generated in the plating bath 3 during a first support roll 307 and the steel strip 2 is easily caught. Thus, dross flaw dross adheres to the steel strip 2 may occur.
[0059]
　Figure 7 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus 400 according to the fourth embodiment. The diameter D401 and the diameter D402 of the second support roll 408 of the first support roll 407 in a continuous molten metal plating apparatus 400 is set to a value that does not satisfy Expression (7). In other words, in the fourth reference example, the diameter D402 of the first support diameter D401 and second support rolls 408 of the roll 407, the range of the upper right side of the region boundary line B4 in D1-D2 plane shown in FIG. 2 It is set to a value of the inner.
[0060]
　As shown in FIG. 7, in the fourth reference example, as compared to continuous molten metal plating apparatus 1 according to this embodiment shown in FIG. 1, the diameter D401 of the first support roll 407 and the second support the diameter D402 of the roll 408 is large. With increasing size of the first support roll 407 and the second support roll 408, in order to prevent interference between the rolls is adjusted in a direction approaching the position of the sink roll 406 to the bottom F400 of the plating tank 4 need arises. Thus, dross deposited on the bottom F400 of the plating tank 4 is liable to be wound up by rotation of the sink roll 406. Thus, it becomes easy dross generated in the plating bath 3 is caught between the first support roll 407 or the second support roll 408 and the steel strip 2. Thus, dross flaw dross adheres to the steel strip 2 may occur.
[0061]
　As described above, in the continuous molten metal plating apparatus 1 according to the present embodiment, the diameter D1 of the first support roll 7 from the equation (1) to satisfy the condition of Equation (4), a second support roll 8 vertical distance L between the rotation axis of the diameter D2 and the first and the axis of rotation of the support roll 7 and the second support roll 8 is set. Thereby, it is possible to suppress scratches, roll defects, the generation of scratches on the surface of the plated steel strip of dross defects like. Thus, it is possible to improve the quality of the plated steel strip.
[0062]
　<3. Applications>
　Next, with reference to FIG. 8, will be described first adjustable applications the vertical position of the support rolls 7.
[0063]
　Figure 8 is a schematic diagram showing an example of a schematic configuration of a continuous molten metal plating apparatus 10 according to an application example. In Figure 8, mainly configured around the first support roll 7 and the second support roll 8 is shown. Continuous molten metal plating apparatus 10 according to an application example is different from the continuous molten metal plating apparatus 1 according to this embodiment shown in FIG. 1, comprises an adjustable adjusting unit in the vertical direction of the position of the first support roll 7 .
[0064]
　Function of the adjustment unit, for example, may be implemented by a first support to drive the arm 20 and the arm 20 to grip the roll 7 unillustrated driving apparatus shown in FIG. The first support roll 7, the lower portion of the arm 20 is rotatably fixed. The top of the arm 20 is connected from the bath surface of the plating bath 3 projects upward, an external driving device (not shown) of the plating bath 3. Arm 20, by the drive device, which is movable in the vertical direction, by adjusting the vertical position of the arm 20, it is possible to adjust the vertical position of the first support roll 7. Incidentally, the arms 20, by the drive device may be movable in the horizontal direction.
[0065]
　According to the adjustment unit according to the application example, by adjusting the vertical position of the first support roll 7, the axis of rotation of the first support roll 7 and the vertical direction between the rotation axis of the second support roll 8 it is possible to adjust the distance L. For example, as shown in FIG. 8, when the arm 20 is positioned at the lowermost portion of the movable region, the distance L becomes the maximum value Lmax. On the other hand, when the arm 20 is located at the top of the movable region, the distance L is a minimum value Lmin. In this case, the distance L is made adjustable within the range of Lmax from Lmin. Therefore, by setting the Lmin and Lmax properly, the first support diameter D1 of the roll 7, the second diameter D2 and the first support roll 8 of the support roll 7 of the rotary shaft and the second support roll 8 distance L in the vertical direction of the rotating shaft, from the equation (1) so as to satisfy the condition of equation (4) can be previously adjusted in the vertical direction of the position of the first support roll 7.
[0066]
　METHOD continuous molten metal plating will be described using a continuous molten metal plating apparatus 10 according to an application example of the above configuration. The method continuous molten metal plating comprises the steps of preliminarily adjusting the vertical position of the first support roll 7, a step of changing a conveyance direction of the steel strip 2 upward by a sink roll 6, the first support roll 7 When, and a step of passing the steel strip 2 while being sandwiched between the second support roll 8. A step of preliminarily adjusting the vertical position of the first support roll 7, the diameter D1, so that the diameter D2 and the distance L satisfies the condition of equation (4) from equation (1), first support roll 7 a step of preliminarily adjusting the vertical position of the. According to the continuous molten metal plating process, even if at least one of the diameter of the first support roll 7 and the second support roll 8 has decreased due to wear or re-grinding, wherein the formula (1) ( the diameter D1 that satisfies the condition 4), it is possible to maintain the relationship between the diameter D2 and the distance L. In this case, by using the control device, depending on the amount of reduction of the diameter of the first support roll 7 and the second support roll 8, diameter such as to satisfy the condition of Equation (4) from equation (1) D1, the diameter the position of the D2 and the distance L, preferably positioned control arm 20.
Example
[0067]
　In order to confirm the effect of the present invention, in the case of applying various settings to the diameter D2 of the first diameter D1 and the second support roll 7 support roll 8, after continuous molten metal plating test plated steel strip for scratches the surface was evaluated. The plating test in the evaluation, to the conveying speed of the steel strip 2 180 m / min, the molten zinc used as the molten metal forming the plating bath 3, the plate thickness as the steel strip 2 is 0.6mm or more, be 0.7mm or less plate width is more than 950 mm, using coils of carbon content of 0.6% or less of cold rolled carbon steel or less 1820Mm.
[0068]
　In the evaluation, we carried out 80 coiled about the continuous hot-dip plating of the above test conditions, as scratches on the surface of the plated steel strip was evaluated visually for scratches, each roll flaws and dross defects. The score mark, a case where the ratio of the coil which scratches are formed on the plated steel strip of 80 pieces of the coil is less than 3% as acceptable, was evaluated when the ratio is 3% or more as unacceptable . For roll flaws, the case where the ratio of the coil roll scratches are formed on the plated steel strip of 80 pieces of the coil is less than 3% as acceptable, was evaluated when the ratio is 3% or more as unacceptable . The dross defects, the case where the ratio of the coil which dross flaw formed plated steel strip of 80 pieces of the coil is less than 3% as acceptable, was evaluated when the ratio is 3% or more as unacceptable . In Table showing the evaluation results for each flaw to be described later, for each flaw, a case where the ratio of coil defect is formed is less than 1.5% indicated by A, the ratio of coil defect is formed the case is less than 1.5% or more 3% indicated by B, submitted a case where the ratio of coil defect is formed is 3% or more by C. A and B correspond to passing rating, C correspond to fail evaluation.
[0069]
　Further, in the following Examples and Comparative Examples were set pushing amount P1 as basis weight is uniform. Incidentally, the uniformity of the basis weight irradiates γ rays plated steel strip traveling, performed by detecting the intensity of the fluorescent X-rays to be received, evaluated by measuring the coating weight in the width direction It was.
[0070]
　First, the distance L is set to 200 mm, compared with a diameter D1 and Example 8 and Comparative Example 1 various set values ​​from Example 1 was applied to the diameter D2 of the second support roll 8 of the first support roll 7 Example in 8 shows the evaluation results for the flaws in the surface of the plated steel strip in Table 1 below.
[0071]
[Table 1]

[0072]
　9, in the D1-D2 plane, the diameter D1 and diameter D2 of Comparative Example 8 dot J8 and Comparative Examples 1 dot J1 respectively corresponding to the set value of the diameter D1 and diameter D2 of Example 8 from Example 1 dot K8 are shown respectively in the setting value from the corresponding dot K1. Further, in FIG. 9, the boundary line B104 from the boundary line B101 represented by the formula (8) by Equation (11) is shown in the case where the distance L is set to 200 mm.
[0073]
　As shown in FIG. 9, the dot J8 dot J1 respectively corresponding to the set value of the diameter D1 and diameter D2 of Example 8 from Example 1, a region surrounded by a boundary line B104 from the boundary line B101 in D1-D2 plane located in the E101. Therefore, satisfying the condition in Example 8 from Example 1, the diameter D1 and diameter D2 is set within the range of the region E101, the diameter D1, the diameter D2 and the distance L from Formula (1) Formula (4) . Example 8 For this example 1, as shown in Table 1, scratches, all of which pass evaluation is made on the roll flaw and dross defects, scratches, occurrence of roll scratches and dross flaw suppressed it is has been confirmed that is.
[0074]
　On the other hand, as shown in FIG. 9, the dot K8 dot K1 respectively corresponding to the set value of the diameter D1 and diameter D2 of Comparative Example 8 Comparative Example 1, located outside the area E101. Thus, in Comparative Example 8 Comparative Example 1, since the diameter D1 and diameter D2 is set outside the range of the region E101, diameter D1, the diameter D2 and the distance L satisfy the condition of Equation (4) from equation (1) Absent.
[0075]
　In Comparative Example 1 and Comparative Example 2, as shown in Table 1, and failure evaluation is made on scratches, it was confirmed that scratches lot occurs. Dot K1 and dot K2 corresponding to the set value of the respective diameters D1 and diameter D2 of Comparative Example 1 and Comparative Example 2, located in the left area of ​​the boundary line B101. Thus, as described with reference to FIG. 4, by faulty rotation of the first support roll 7 has occurred, it is considered to scratches occurred on the steel strip 2.
[0076]
　In Comparative Examples 3 and 4, as shown in Table 1, and failure evaluation is made on a roll flaw, it was confirmed that the roll scratches lot occurs. Dot K3 and dot K4 corresponding to the set value of the respective diameters D1 and diameter D2 of Comparative Examples 3 and 4, located in the upper section of the boundary line B 102. Thus, as described with reference to FIG. 5, by dross adhering to the first support roll 7 and the second support roll 8 is transferred to the steel strip 2, it is considered to roll flaws occurred.
[0077]
　In Comparative Examples 5 and 6, as shown in Table 1, fail evaluation has been made on the dross defects, it was confirmed that dross defects many occurred. Dot K5 and dot K6 corresponds to the set value of the respective diameters D1 and diameter D2 of Comparative Example 5 and Comparative Example 6 is positioned below the region of the boundary line B 103. Thus, as described with reference to FIG. 6, by the dross is involved between the first support roll 7 and the steel strip 2, it is considered to dross defects occurred.
[0078]
　In Comparative Examples 7 and 8, as shown in Table 1, fail evaluation has been made on the dross defects, it was confirmed that dross defects many occurred. Dot K7 and dot K8 corresponding to the set value of the respective diameters D1 and diameter D2 of Comparative Examples 7 and 8, the upper right side area of ​​the boundary line B 104. Thus, as described with reference to FIG. 7, by the dross is involved in the first support roll 7 and the second support between the roll 8 and the steel strip 2, it is considered to dross defects occurred.
[0079]
　Then, the distance L is set to 300 mm, compared the first support roll 7 having a diameter D1 and a second support roll Example 16 from Example 9 in which the application of the various setting values ​​to the diameter D2 of 8 and Comparative Example 9 in example 16, it shows the evaluation results for the flaws in the surface of the plated steel strip in Table 2 below.
[0080]
[Table 2]

[0081]
　In Figure 10, the D1-D2 plane, the diameter D1 and diameter D2 of Comparative Example 16 from the dot J16 and Comparative Example 9 dots J9 respectively corresponding to the set value of the diameter D1 and diameter D2 of Example 16 from Example 9 dot K16 dot K9 respectively corresponding to the set value is shown. Further, in FIG. 10, the boundary line B204 from the boundary line B201 represented by the formula (11) from equation (8) is shown in the case where the distance L is set to 300 mm.
[0082]
　As shown in FIG. 10, the dot J16 dot J9 respectively the set value corresponding diameter D1 and diameter D2 of Example 16 from Example 9, a region surrounded by a boundary line B204 from the boundary line B201 in D1-D2 plane located in the E201. Therefore, satisfying the condition in Example 16 from Example 9, the diameter D1 and diameter D2 is set within the range of the region E201, the diameter D1, the diameter D2 and the distance L from Formula (1) Formula (4) . In Example 16 from such an embodiment 9, as shown in Table 2, scratches, all of which pass evaluation is made on the roll flaw and dross defects, scratches, occurrence of roll scratches and dross flaw suppressed it is has been confirmed that is.
[0083]
　On the other hand, as shown in FIG. 10, the dot K16 dot K9 corresponding respectively to the set value of the diameter D1 and diameter D2 of Comparative Example 16 Comparative Example 9 is located outside the area E201. Thus, in Comparative Example 16 Comparative Example 9, the diameter D1 and diameter D2 is set outside the range of the region E201, diameter D1, the diameter D2 and the distance L satisfy the condition of Equation (4) from equation (1) Absent.
[0084]
　In Comparative Example 16 Comparative Example 9, in the same manner as in Comparative Example 8 Comparative Example 1, as shown in Table 2, scratches, fail evaluation has been made for at least one of the rolls flaws and dross defects, scratches, it was confirmed that at least one flaw of the roll flaws and dross flaw many occurred. Specifically, in Comparative Example 9 and Comparative Example 10, as shown in Table 2, and fail evaluation is made on scratches, it was confirmed that scratches lot occurs. In Comparative Example 11, as shown in Table 2, the scratches and roll flaws and failure evaluation is performed, it was confirmed that scratches and roll flaws many occurred. In Comparative Example 12, as shown in Table 2, and fail evaluation is made on a roll flaw, it was confirmed that the roll scratches lot occurs. In Comparative Example 16 Comparative Example 13, as shown in Table 2, failure evaluation has been made on the dross defects, it was confirmed that dross defects many occurred.
[0085]
　From the results, the diameter D1 of the first support roll 7, the vertical distance between the rotation axis of the diameter D2 and the first support roll 7 of the second support roll 8 and the rotation shaft of the second support roll 8 L but by being set from equation (1) so as to satisfy the condition of equation (4), it was confirmed that it is possible to suppress the occurrence of scratches on the surface of the plated steel strip. Thus, according to a continuous molten metal plating apparatus 1 according to this embodiment, it is possible to improve the quality of the plated steel strip.
[0086]
　<4. Conclusion>
　As described above, according to this embodiment, first diameter D1 of the support roll 7, the axis of rotation of the diameter D2 and the first support roll 7 of the second support roll 8 and the second support roll vertical distance L between the rotation shaft 8 is set from equation (1) so as to satisfy the condition of equation (4). Thereby, it is possible to suppress the occurrence of scratches on the surface of the plated steel strip. Thus, it is possible to improve the quality of the plated steel strip.
[0087]
　In the above, by adjusting the horizontal position of the first support roll 7, an example has been described of adjusting the push-in amount P1, the technical scope of the present invention is not limited to the embodiment. For example, by adjusting the horizontal position of the second support roll 8 with respect to the first support roll 7, it may be adjusted pressing amount P1. Incidentally, in this case, to maintain the horizontal position relationship of the gas wiping nozzle 9 and the second support roll 8, it is necessary to adjust the horizontal position of the gas wiping nozzle 9.
[0088]
　Further, in the above, the adjustment unit has been described an example that is implemented by a drive device for driving the arm 20 and the arm 20, the technical scope of the present invention is not limited to the embodiment. Adjustment unit adjusts the vertical position of the first support roll 7 If possible, it may be other configurations.
[0089]
　Having described in detail preferred embodiments of the present invention with reference to the accompanying drawings, the present invention is not limited to the embodiment. It would be appreciated by those skilled in the relevant field of technology of the present invention, within the scope of the technical idea described in the claims, it is intended to cover various modifications and applications , also such modifications are intended to fall within the technical scope of the present invention.
DESCRIPTION OF SYMBOLS
[0090]
1,10,100,200,300,400 continuous molten metal plating apparatus
2 steel strip
3 baths
4 Plating bath
5 snout
6,406 sink roll
7,107,207,307,407 first support roll
8, 108, 208,308,408 second support rolls
9 gas wiping nozzle
20 arm

The scope of the claims
[Requested item 1]
　Provided in the plating bath, a sink roll for changing the conveyance direction of the steel strip upwardly
　within the plating bath, positioned above the sink roll, the first in contact with the surface of the steel strip in contact with the sink roll of the support roll,
　in said plating bath, positioned above said first support roll, and a second support roll in contact with the surface opposite to the surface of the steel strip in contact with the sink roll
　comprising a
　said the diameter of the first support roll, the vertical distance between the rotation axis of said second support roll diameter and wherein the rotation axis of the first support roll second support rolls, the following equation (1) satisfy the formula (4), a continuous molten metal plating apparatus.
[Number 1]

However,
D1: the first support roll diameter (mm)
D2: the second support roll diameter (mm) L:
wherein the rotation axis of the first support roll second support rolls distance of vertical direction between the rotation axis (mm).
[Requested item 2]
　Comprise adjusting unit capable of adjusting the vertical position of said first support roll, a continuous molten metal plating apparatus according to claim 1.
[Requested item 3]
　The sink roll provided in the plating bath, the step of changing the conveying direction of the steel strip upwardly
　within the plating bath, positioned from above the sink roll in contact with the surface of the steel strip in contact with the sink roll a first support roll, in said plating bath, between the first positioned above the support roll, a second support roll in contact with the surface opposite to the surface of the steel strip in contact with the sink roll scissors while the steps of passing said steel strip
　comprises,
　rotation of the first support roll diameter, wherein the rotation axis of the second support roll diameter and said first support roll second support rolls the vertical distance between the axes, so as to satisfy the condition of equation (4) from the following equation (1), comprising the step of preliminarily adjusting the vertical position of said first support roll,
　continuous Molten metal plating method.
[Number 2]

However,
D1: the first support roll diameter (mm)
D2: the second support roll diameter (mm) L:
wherein the rotation axis of the first support roll second support rolls distance of vertical direction between the rotation axis (mm).