JP2022094422A - In-bath roller polishing blade, polishing device, and plating apparatus - Google Patents

Abstract

To provide an in-bath roller polishing blade capable of suppressing that a contact surface pressure between a blade and the periphery of an in-bath roller so as to be lower in the early stage of use without providing complicated control means to be higher after the subsequent middle stage; an in-bath roller polishing device using the same; and molten metal plating apparatus.SOLUTION: In a blade 1 for polishing the periphery of an in-bath roller 5 dipped into a molten metal bath 10, the cross sectional shape of the tip of the blade in the longitudinal direction has a thickness reduced from the tip of the blade in the longitudinal direction to the rear end side or a thickness converged on a constant value.SELECTED DRAWING: Figure 1

Description

The present invention has a bath roll polishing blade, specifically a blade for polishing a bath roll immersed in a molten metal plating bath, a bath roll polishing device having the blade, and a molten metal having the bath roll polishing device. Regarding plating equipment.

In the hot-dip galvanizing tank used in the continuous hot-dip galvanizing process of steel strips, which is a typical example of hot-dip metal plating of metal strips, impurities such as zinc iron compounds suspended in the plating bath support sink rolls and baths. When it adheres to the outer peripheral surface of the roll (hereinafter collectively referred to as the roll in the bath), this deposit is transferred to the steel strip in contact with the roll in the bath, and as a result, defects such as dents are found on the manufactured plated steel plate. Occurs.

In order to prevent the occurrence of defects such as the above-mentioned dents, a plate-shaped blade having a considerable thickness, width and length is used, and one side of the blade in the width direction is pressed against the outer peripheral surface of the bath roll. A method of scraping off deposits by polishing the outer peripheral surface is known. In this method, the thickness direction of the blade is the rotational peripheral speed direction of the bath roll, the width direction of the blade is the body width direction of the bath roll, and the length direction of the blade is a direction perpendicular to the thickness direction and the width direction. Is.

In the above-mentioned method of polishing the outer peripheral surface of the bath roll with a blade, Patent Document 1 states that the width is narrower than the body width of the bath roll and narrower than the plate width of the steel plate (for example, 10 of the body width of the bath roll). %) The method of reciprocating in the width direction while pressing the blade against the outer peripheral surface of the roll in the bath with a constant pressing load is disclosed. This blade has a shape in which the thickness of the tip portion is constant in the length direction.

Patent Document 2 discloses a method of suppressing the vibration of the bath roll by specifying the contact position and the inclination angle of the blade with respect to the outer peripheral surface of the bath roll. The tip of the blade has a shape in which the thickness increases from the tip to the rear end in the length direction, or the thickness becomes more constant. The width of this blade is larger than the body width of the bath roll, and there is no disclosure of the reciprocating motion in the width direction while pressing against the bath roll.

Patent Document 3 discloses a blade in which the thickness of the tip portion has a constant shape in the length direction and the width of the blade is longer than the body width of the roll in the bath in order to improve the polishing ability.

Patent Document 4 discloses that in order to keep the contact surface pressure of the blade substantially constant, a weight for the reduction is added to the weight of the blade itself to obtain a pressing load. This blade is considered to have a shape in which the thickness of the tip portion is constant in the length direction. It should be noted that this blade is disclosed to have a width narrower than the plate width of the steel plate.

That is, the conventional blade has a shape in which the thickness increases from the tip end side in the length direction to the rear end side, or the thickness becomes more constant (Patent Document 2), or the thickness of the tip portion is constant in the length direction. The shape (Patent Documents 1, 3 and 4).

When the contact width and pressing load of the blade are constant, the contact surface pressure of the blade is inversely proportional to the contact thickness. The contact width and contact thickness refer to the blade width direction dimension and the blade thickness direction dimension of the contact surface between the outer peripheral surface of the roll in the bath and the blade, respectively. In the tapered blade indicated by reference numeral B in FIG. 3, the contact thickness increases or further shifts to a constant thickness with the lapse of use time, so that the contact surface pressure changes as shown by the solid line in FIG. Further, in the blade having a constant thickness indicated by reference numeral C in FIG. 3, the contact thickness is constant even after the lapse of use, so the contact surface pressure changes as shown by the broken line in FIG.

In addition, in FIG. 3 and FIG. 2 described later, the start of the steady state is defined as “initial use” without considering the unsteady state for a very short time immediately after the start of contact between the blade and the roll in the bath.

JP-A-2007-254875A Jikkenhei 6-83762 Gazette Japanese Unexamined Patent Publication No. 2019-19343 Japanese Unexamined Patent Publication No. 2005-281789

On the other hand, in order to protect the roll in the bath from erosion by zinc and the wrapping and adhesion of impurity particles such as zinc-iron alloy, the outer peripheral portion of the roll in the bath is treated to form a film by thermal spraying or welding overlay. In some cases. From the viewpoint of extending the life of the roll in the bath, it is better not to press the film in contact with the blade as much as possible. Further, since the coating film is in a healthy state at the initial stage of use of the blade and no impurity particles adhere to the roll in the bath, it is desirable that the polishing ability is relatively low from the viewpoint of preventing damage to the coating film. On the other hand, after the time of the initial stage of using the blade has elapsed and after the middle stage after that, the coating film on the outer peripheral surface of the bath roll is damaged, and the impurity particles tend to adhere to the bath roll. It is desirable that the polishing ability of the blade is relatively high from the viewpoint of reliably removing the adhered deposits. This polishing ability can be evaluated by measuring the contact surface pressure between the blade and the outer peripheral portion of the roll in the bath, and it is said that the higher the contact surface pressure, the higher the polishing ability.

However, in the above-mentioned conventional blade, as shown in FIG. 3, the contact surface pressure is at the maximum at the beginning of use and decreases or becomes constant with the passage of use time (B), or even after the use time elapses. It is either (C), which is about the same as when it was first used. In order to realize the above-mentioned desirable usage pattern in which the polishing capacity is lowered in the initial stage of use of the blade and then increased, the pressing load of the blade is low in the initial stage of use and high in the subsequent middle stage and thereafter. If a complicated control means for realizing the above is provided, the equipment cost and the operation cost for that purpose are increased, which is disadvantageous in terms of operation.

In view of the above circumstances, the present invention is in the blade and the bath without providing a complicated control means for increasing the pressing load of the blade for polishing the roll in the bath immersed in the molten metal plating bath as the use progresses. A blade for polishing a roll in a bath, a roll polishing device in a bath using the blade, and a molten metal that can keep the contact surface pressure with the outer peripheral portion of the roll low in the initial stage of use and then increase it in the middle stage and thereafter. Provides a plating apparatus.

The present inventor has diligently studied to solve the above-mentioned problems, and as a result, came up with a blade shape in which the tip in the length direction is the thickest and the thickness decreases toward the rear end, and the present invention is made. .. That is, the present invention is as follows.
[1] A blade for polishing the outer peripheral portion of a roll in a bath immersed in a molten metal bath.
The blade is characterized in that the cross-sectional shape of the tip portion of the blade in the length direction is a shape in which the thickness decreases from the tip end side in the length direction of the blade to the rear end side.
[2] The blade according to [1], wherein the cross-sectional shape of the tip portion of the blade in the length direction is a shape in the length direction in which the thickness further converges to a constant value.
[3] The blade according to [1] or [2], wherein the cross-sectional shape of the tip of the blade in the length direction is trapezoidal.
[4] The blade according to [3], wherein one of the bottom angles of the trapezoid on the side that comes into contact with the roll in the bath is set to 25 to 85 °.
[5] The blade according to any one of [1] to [4], wherein the roll in the bath has a coating film on the outer peripheral portion.
[6] The width of the blade at the tip thereof is larger than the width of the metal strip wound around the bath roll and smaller than the body width of the bath roll [1] to [5]. The blade described in any one.
[7] The in-bath roll polishing apparatus having the blade according to any one of [1] to [6].
[8] A molten metal plating apparatus having the in-bath roll polishing apparatus according to [7].

According to the present invention, while the bath roll is sound, the contact surface pressure is suppressed to avoid wear of the outer peripheral portion of the bath roll, and further, high contact occurs when alloy impurities wrap around and adhere to the bath roll. As a surface pressure, reliable removal of deposits can be achieved by a simple method, and therefore, the outer peripheral surface of the bath roll can be stably kept in a healthy state while maintaining the life of the bath roll for a longer period of time. This makes it possible to reduce the frequency of replacing rolls in the bath.

It is a schematic diagram which shows an example which used the blade of this invention for a roll in a bath, (a) is a three-dimensional view, (b) is a sectional view in a blade length direction, (c) is a sectional view in a blade width direction. be. It is a figure which shows the transition of the contact surface pressure with respect to the use time of the thickened type (total and partial) blade of this invention schematically. It is a figure which shows the transition of the contact surface pressure with respect to the use time of the conventional tapered type and constant thickness type blades schematically. It is the schematic of the cross section in the blade length direction which shows the example of various shapes of the tip part of the blade of this invention. It is the schematic of the cross section in the blade length direction which shows the preferable shape of the blade of this invention. It is a figure explaining the problem when the blade is wider than a roll in a bath. It is explanatory drawing of the method of determining the width of a blade. It is the schematic of the cross section in the length direction which shows the dimension of the blade in an Example. It is a schematic diagram which shows an example of the roll polishing apparatus in a bath of this invention. It is a schematic diagram which shows an example of the molten metal plating apparatus of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
For example, as shown in FIG. 1, it is premised that the blade 1 of the present invention is a blade 1 that polishes the outer peripheral portion of the roll 5 in the bath immersed in the molten metal bath 10. In the present invention, the bath roll 5 includes a sink roll 5 ₁ and a bath support roll 52, and one or _both of them are to be polished. In the following embodiment, as shown in FIG. A case where the sink roll 5 ₁ is to be polished will be described as an example.

[Melted metal bath]
The molten metal bath 10 is, for example, a zinc-plated bath 10, and the temperature of the bath is 430 to 700 ° C. The zinc plating bath 10 is used, for example, in a continuous hot dip galvanizing line for manufacturing steel sheets for automobiles. The following embodiment will be described with an example in which the metal strip 6 is a steel plate 6. The galvanized steel plate 6 has a plate thickness of 0.30 to 6.0 mm, a plate width of 600 to 2500 mm, and a plate passing speed of 30 to 300 m / min.
In order to control the alloying reaction between the steel sheet and Zn, about 0.1 to 55.0% by mass of Al may be added to the zinc plating bath 10. In zinc plating, the reaction product of Fe derived from the steel sheet 6 and Zn and / or Al derived from the plating bath wraps around the roll 5 in the bath and adheres to the impurities particles having a diameter of about 10 μm or more. It causes defects in the pressed flaws of the steel plate 6. The frequency of occurrence of the impurity particles is about once every 1 to 24 hours.

[Roll in a soaked bath]
The roll 5 in the bath rotates due to contact with the passing steel plate 6. As the material of the roll 5 in the bath, stainless steel is used from the viewpoint of ensuring corrosion resistance to hot-dip zinc. The size of the roll 5 in the bath is 600 to 1000 mm in the roll diameter and 1000 to 3000 mm in the body width in the case of the sink roll 51, and the roll diameter is 150 to 350 mm and the body width is 150 to 350 mm in the case of the support roll _{5 2 in} the bath. It is the same as the case of the sink roll ₅₁ .
Further, the body width of the bath roll 5 is set to be 200 to 500 mm larger than the plate width of the steel plate 6.
The roll 5 in the bath preferably has a coating film for protecting the roll base on the outer peripheral portion in order to extend the service life in the bath.
Examples of the coating include a welded overlay coating of a material such as WC and stellite and a thermal spray coating of a material such as WC and WC-Co.
When a conventional blade is used for the roll 5 in the bath, the surface texture of the roll becomes unhealthy in about two weeks, and the quality problem of the steel plate 6 becomes remarkable. On the other hand, when the blade of the present invention is used, the surface texture of the roll can be maintained in a healthy state for 3 weeks or more, and the quality of the steel sheet can be guaranteed.

[Blade material]
As the material of the blade 1, any of stainless steel, heat-resistant steel, heat-resistant non-ferrous base alloy and the like can be preferably used.

[Blade shape]
Under the above-mentioned premise, the present invention has a shape in which the cross-sectional shape of the blade 1 in the length direction decreases in thickness from the tip end side in the length direction of the blade 1 to the rear end side (hereinafter, also referred to as a tipped shape). .). The tapered shape has a shape in which the thickness decreases from the tip end side in the length direction of the blade 1 to the rear end side over the entire length direction of the blade 1 (hereinafter, also referred to as an overall tapered shape). (See A1 in FIG. 2), and there is a shape in the length direction in which the thickness converges to a constant value. The latter "shape in the length direction in which the thickness further converges to a constant value" means that the length of the blade 1 is such that the thickness decreases from the tip end side in the length direction of the blade 1 to the rear end side. A part of the area on the tip side in the longitudinal direction, and the remaining area has a constant thickness equal to the thickness of the rear end of the part of the area (hereinafter, also referred to as a partially thickened shape). (See A2 in FIG. 2).

In the present invention, the partially tapered shape is preferable to the totally tapered shape from the viewpoint of material saving and ease of manufacture of the blade 1.

The thickness of the blade 1 is preferably 10 to 40 mm. If it is less than 10 mm, the rigidity of the blade 1 is insufficient, and if it exceeds 40 mm, the weight of the blade is unnecessarily increased.

Since the blade 1 of the present invention has a tapered shape, when the contact width and the pressing load are constant, the contact with respect to the usage time of the total tapered shape (A1) and the partially tapered shape (A2) is shown in FIG. As shown by the transition of the surface pressure, the contact surface pressure was the minimum at the beginning of use for both A1 and A2, the contact surface pressure increased with the lapse of the use time, and in A1, the contact surface pressure continued to increase to the rear end. In A2, the contact surface pressure shifts to a constant state while increasing, but in any case, according to the tapered blade 1 of the present invention, only by setting the thickness dimension in the blade length direction cross section. When the contact surface pressure is suppressed while the bath roll 5 is healthy at the initial stage of use to avoid wear of the outer peripheral portion of the bath roll 5, and when the alloy impurities start to wrap around the bath roll 5. As a high contact surface pressure, it is possible to surely remove the deposits.

The contact surface pressure was obtained as follows. That is, the amount of wear at a certain polishing length was estimated from the relationship between the cumulative polishing length and the cumulative wear amount when the pressing load was constant, and the contact surface pressure was calculated from the contact area and the pressing load at that time.

As long as the blade of the present invention has a thickened tip, the more specific shape of the tip portion is not particularly limited, and various shapes can be tolerated. For example, FIG. 4 shows an example in which the cross section of the blade 1 in the length direction is a trapezoidal shape (a), a trumpet-shaped shape (b), and a bell-shaped shape (c) among the tapered shapes. In addition, although the case where the thickness center line (dashed line) is a straight line (the cross-sectional shape is symmetrical) is illustrated in FIGS. As shown in d), (e) and (f), the thickness center line may be curved (the cross-sectional shape is asymmetrical).

The blade 1 of the present invention can be manufactured by rolling a flat plate as a material and changing the rolling reduction in the thickness direction in the length direction. Further, in the case of a partially thickened portion, the thickened portion can be manufactured by roll molding or the like and welded to a portion having a constant thickness.

Further, the cross-sectional shape of the tip portion of the blade 1 of the present invention is a trapezoid (for example, FIG. 4A or FIG. 4D) in which the thickness change in the length direction is linear from the viewpoint of ease of modeling. ) Is preferable. Since the trapezoid is thick, the length of the lower base of the trapezoid is longer than the length of the upper base.

Further, as shown in FIG. 5, it is preferable that one of the two bottom angles on the lower bottom side (the side that abuts on the roll in the bath) of the trapezoid has an angle θ = 25 to 85 °. More preferably, the angle θ = 50 to 60 °. Further, from the viewpoint of increasing the polishing ability, as shown in FIG. 5, it is possible to arrange one base angle side within the range of the angle θ on the approach side of the outer peripheral portion of the roll into the region of the contact thickness. preferable. When both bottom angles are within the range of the angle θ, any bottom angle side may be arranged on the approach side of the outer peripheral portion of the roll into the region of the contact thickness.

[Blade width]
In the present invention, it is preferable (i) that the width of the blade 1 at the tip thereof is larger than the plate width of the metal band (for example, a steel plate) 6 wound around the bath roll 5 and smaller than the body width of the bath roll 5. .. FIG. 1 illustrates this preferred embodiment. The effect of this is that when the blade 1 is wider than the bath roll 5 as in Patent Documents 1 and 3 (ii) and the blade 1 is narrower than the steel plate 6 as in Patent Documents 2 and 4. This will be described in comparison with the case (iii).

In the case of (ii) above, as shown in FIG. 6, the entire width of the roll 5 in the bath can be polished while the blade 1 is stationary (FIG. 6 (a)). However, since only the contact portion with the roll 5 in the bath is scraped during use (FIG. 6 (b)), an unworn portion 15 is generated at both ends in the width direction of the blade 1 (FIG. 6 (c)). On the other hand, the blade 1 may be temporarily opened (separated from the roll in the bath) and then reused (re-contacted) as needed during use. Further, the roll 5 in the bath is usually provided with a play allowance in the roll axis direction in order to reduce the load on the thrust receiver due to the thrust force and extend the roll life (see FIG. 7 described later). The size of this play allowance is about 3 to 15 mm per side. Therefore, the bath roll 5 moves in the roll axis direction while the blade 1 is open, and when the blade 1 is reused, the bath roll 5 and the blade 1 are misaligned, and only the unworn portion 15 on one side of the blade 1 is used. May come into contact with the roll 5 in the bath, so-called one-sided pressure reduction (FIG. 6 (d)). In this case, the outer peripheral surface of the bath roll 5 is polished until the unworn portion 15 is worn and the step with the center side is eliminated and the blade comes into contact with the bath roll 5 again at the full width of the blade. It will be insufficient.

On the other hand, in the case of (i) above, as shown in FIG. 1, since the width of the blade 1 is smaller than the body width of the bath roll 5, the blade 1 comes into contact with the bath roll 5 in full width during use. Since it is scraped evenly, the above-mentioned undured portions do not occur at both ends of the blade 1. Therefore, even if the bath roll 5 moves in the roll axis direction at the time of opening the first blade following the first use of the blade, the above-mentioned one-sided reduction does not occur at the time of the subsequent use of the second blade.

However, if the amount of movement of the bath roll 5 in the roll axis direction is larger than the difference between the body width of the bath roll 5 and the width of the blade 1, the roll axis direction of the bath roll 5 during the second blade opening Due to the movement of the blade 1, one side in the width direction of the blade 1 deviates from the body width region of the bath roll 5, and this disengaged side becomes the above-mentioned uncured portion when the blade is used for the third time, which may lead to the above-mentioned one-sided pressure reduction. be. Therefore, in order to avoid this, as shown in FIG. 7, the difference (ba) between the body width b of the bath roll 5 and the width a of the blade 1 is the amount of movement of the bath roll 5 in the roll axis direction (=). It is preferable to determine the width a of the blade 1 so as to be equal to or larger than the set amount of play allowance 2y + the estimated amount of thrust receiving wear 2z), that is, so as to satisfy the plate width <a≤b-2y-2z.

Further, in the case of the above (iii), since the width of the blade 1 is smaller than the plate width of the steel plate 6, a device for reciprocating the blade 1 in the roll axis direction is required, and the device for reciprocating the blade 1 uses a blade. The blade 1 may be stationary due to a failure during the process, and during this stationary period, only a part of the steel plate 6 passing region on the outer peripheral surface of the roll 6 in the bath may be polished.

On the other hand, in the above (i), since the width a of the blade 1 exceeds the plate width of the steel plate 6 (FIGS. 1 and 7), the steel plate 6 on the outer peripheral surface of the roll 5 in the bath under the stationary state of the blade 1. The passage area can be thoroughly polished. A device for reciprocating the blade 1 is not particularly required, but it may be provided. Even if alloy impurities are wound around both ends of the roll outside the steel plate 6 passage region on the outer peripheral surface of the roll 5 in the bath, transfer to the steel plate 6 does not occur, so that there is no adverse effect on the plated product.

[Roll polishing device in bath]
The bath roll polishing device of the present invention is a bath roll polishing device having the above-mentioned blade 1. It preferably has a blade elevating means 8 that elevates and elevates the blade 1, for example, as shown in FIG. According to this, it is easy to switch between the used state and the open state of the blade 1. Further, it is preferable that the blade elevating means 8 is provided with means for executing a method (not shown) for making the pressing load of the blade 1 constant. As a method of making the pressing load constant, for example, the torque of the roll to be pressed is detected by a torque sensor, and the pressing load operation amount (for example, when the air cylinder is used as the pressing drive source) is used so that the sensor output becomes the target value. Any method of adjusting the air pressure) or, for example, a method of applying a constant load at all times by a simpler floating box type buoyancy can be preferably used.

[Fused metal plating equipment]
The molten metal plating apparatus of the present invention may be the same as a general molten metal plating apparatus except that it has the above-mentioned bath roll polishing apparatus of the present invention. As a typical example of a general hot-dip metal plating device, the continuous hot-dip zinc plating device for the steel plate 6 shown in FIG. 10 includes a hot-dip metal bath 10 such as a zinc-plated bath in addition to the in-bath roll 5, the blade 1 and the blade elevating device 8. Wiping to adjust the plating adhesion amount of the plating tank 20 holding the 10 and the snout 21 for feeding the steel plate 6 from the annealing furnace (not shown) into the zinc plating bath 10 and the steel plate 6 leaving the zinc plating bath 10. A nozzle 22 is provided.

The present invention was carried out in a hot-dip galvanized steel sheet production line in which a steel sheet is zinc-plated by the continuous hot-dip galvanizing apparatus shown in FIG. In the example of the present invention, the polishing target of the blade ₁ is the sink roll 51. The steel plate 6 is a steel plate for automobiles, and has a plate thickness of 0.4 to 2.0 mm, a plate width of 700 to 1850 mm, and a plate passing speed of 30 to 230 m / min. The bath composition of the zinc plating bath 10 contains Al: 0.133 to 0.139% by mass and the balance is Zn, and the bath temperature is 458.5 to 464.0 ° C.

_The sink roll 51 is made of stainless steel (SUS316L), has a roll diameter of 760 to 800 mm, a body width of 2200 mm, and has a WC sprayed coating on the outer peripheral portion.
The blade elevating means 8 is composed of an air cylinder.

The blade 1 of the example of the present invention is made of stainless steel (SUS316L), and as shown in FIG. 8, the shape is a partially tapered portion in which the tapered portion 1 ₁ on the tip side is connected to the constant thickness portion 1 ₂ and the dimensions are , As described in FIG. In the example of the present invention, since the tipped portion ₁₁ has an isosceles trapezoidal shape, the bottom angles of both trapezoids are about 68 °.

The width of the blade 1 of 2170 mm is larger than the plate width of the steel plate 6 of 1850 mm and smaller _than the body width of the sink roll 51 of 2200 mm. The width of the blade 1 of 2170 mm is a value calculated by the formula of b-2y-2z in FIG. 7, assuming that b = 2200 mm, play allowance y = 10 mm, and estimated wear amount z = 5 mm.

The dimension of the thickness of the blade 1 was determined as follows.
(I) The contact surface pressure with sufficient polishing capacity and a small amount of polishing debris generated is 0.003 kgf / mm ² based on the results of past operation performance surveys, and the pressing load is constant at ₁₀₀ kgf. The thickness of the constant thickness portion 1 ₂ (= trapezoidal upper bottom t ₁ ) is such that the contact surface pressure during polishing on the rectangular portion 1 ₂ after disappearance due to wear is 0.003 kgf / mm ² above. , 100 / (2170 × 0.003) ≈15 mm.
(Ii) The contact surface pressure at which the polishing capacity is minimized at the beginning of use is set to 0.002 kgf / mm ² based on the results of past operation performance surveys, the pressing load is set to 100 kgf, and the contact surface pressure at the beginning of use is 0 as described above. The cutting _- edge thickness (= trapezoidal bottom t ₀ ) of the tipped portion 11 was determined to be 100 / (2170 × 0.002) ≈23 mm so as to be .002 kgf / mm ² .

In the above (i) and (ii), when the pressing load is large or small with respect to 100 kgf, the blade thickness may be changed accordingly, and the value is not limited.

In determining the length of the tipped portion ₁₁ (height h of the trapezoid), it is assumed that the coating film (WC) on the outer peripheral portion of the sink roll 5 ₁ greatly impairs the protective function within 10 days from the initial use, and the above 10 Assuming that the amount of wear in the blade length direction until the contact thickness of the blade ₁ (SUS316L) decreases from 23 mm to 15 mm due to friction with the coating film (WC) in a day is 10 mm, the tipped portion 11 The length (height h of the trapezoid) was determined to be 10 mm. _The length of the thickened portion 11 may be appropriately changed depending on the type of coating and the material of the blade.

The total length L of the blade 1 is set to 100 mm with a margin so that the blade 1 is not completely worn. The length of the blade 1 needs to be determined in consideration of interference with the surroundings, but in consideration of wear, it is preferably 50 mm or more and as long as possible.

The blade ₁ of FIG. 8 was used for 30 days without replacing the sink roll 51. During use, the blade 1 was repeatedly opened and reused 10 times or more, but no one-sided reduction occurred. The amount of wear of the blade 1 in the length direction after use was 30 mm. No cracks or the like were observed on the blade 1 after use. In addition, during the use of the blade 1 for 30 days, no defects such as dents, which are considered to be due to transfer from the roll deposits in the bath, were confirmed in the manufactured plated steel sheet. Further, when the sink roll 5 ₁ after use was inspected, it was kept in a healthy state except that _minute wrapping of alloy impurities was present at both ends in the width direction excluding the blade contact area of the sink roll 51. Therefore, it was confirmed that the replacement frequency of the sink roll 51 should be set to _once or less every 30 days.

On the other hand, as a comparative example, a tapered blade (see B in FIG. 3) in which the blade thickness from the tip to a length of 100 mm increases from almost zero to 15 mm was used, and other than that, the same as the example of the present invention was used. .. In the comparative example, the polishing ability from the beginning of use is too high and the deterioration of the protective function of the coating film is accelerated. Therefore, when the sink roll 51 is used continuously for 2 _weeks , minute wrapping of alloy impurities is present in the passing area of the steel sheet. There was a risk that defects such as scratches on the steel sheet would occur due to the unhealthy state. Therefore, it was necessary to replace the sink roll 51 _once every two weeks.

Although only the sink roll 5 ₁ is targeted for polishing here, the same configuration can be applied to the case where the support roll 5 ₂ in the bath is targeted.

1, A1, A2 blade (thickened shape of the present invention)
1 ₁ Thick part 1 ₂ Constant thickness part B Blade (conventional tapered type)
C blade (conventional thickness constant type)
5 Bath roll (sink roll with subscript ₁ and bath support roll with subscript ₂ )
6 Metal strip (for example, steel plate)
8 Blade elevating means 10 Molten metal bath (for example, galvanized bath)
20 Plating tank 21 Snout 22 Wiping nozzle

Claims (8)

A blade that polishes the outer periphery of a roll in a bath immersed in a molten metal bath.
The blade is characterized in that the cross-sectional shape of the tip portion of the blade in the length direction is a shape in which the thickness decreases from the tip end side in the length direction of the blade to the rear end side. The blade according to claim 1, wherein the cross-sectional shape of the tip portion of the blade in the length direction is a shape in the length direction in which the thickness further converges to a constant value. The blade according to claim 1 or 2, wherein the cross-sectional shape of the tip of the blade in the length direction is trapezoidal. The blade according to claim 3, wherein one of the bottom angles of the trapezoid on the side that comes into contact with the roll in the bath is set to 25 to 85 °. The blade according to any one of claims 1 to 4, wherein the roll in the bath has a coating film on the outer peripheral portion. The one according to any one of claims 1 to 5, wherein the width of the blade at the tip portion is made larger than the plate width of the metal strip wound around the bath roll and smaller than the body width of the bath roll. The blade described. A roll polishing device in a bath having the blade according to any one of claims 1 to 6. The molten metal plating apparatus having the in-bath roll polishing apparatus according to claim 7.

Images