TW201903172A - Method of producing hot-dipped galvanized steel coil - Google Patents

Abstract

A method of producing hot-dipped galvanized steel coil is provided. Brushing operations in pre-clean step and electrolyzing clean step are processed by brush/back roll, and the brush rolls are hard abrasive brush roll. The driving current of the brush roll is also controlled. Therefore, the nucleation point in unit area of steel coil can be increased without any other spangle-shrink apparatus in the process. The shrink of the spangle size can be reached.

Description

 Method for manufacturing hot dip galvanized steel coil  

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for producing a hot dip galvanized steel coil, and more particularly to a method for producing a hot dip galvanized steel coil for refining the surface of a steel coil.

Hot dip galvanizing (HDG) is one of the currently used galvanizing methods in which iron or steel is completely immersed in molten zinc. Compared with the method of electroplating zinc, the cost of hot dip galvanizing is relatively low. However, the surface appearance, corrosion resistance, oil stain resistance and blackening resistance of hot dip galvanized steel coils are not as good as those of electrogalvanized steel coils.

The reason for the poor surface properties, corrosion resistance, oil stain resistance and blackening resistance of hot dip galvanized steel coils is mainly due to the fact that the zinc layer formed by hot dip galvanizing is composed of larger crystals. Made up of grains. Therefore, it is often inevitable that the hot-dip galvanized zinc layer produces a special structure of zinc flower on the surface, and due to the non-uniformity of the crystal of the zinc flower, the chemical activity of the zinc flower in each region is not the same, thus causing hot dip plating. Zinc steel coils have poor surface appearance, corrosion resistance, oil stain resistance and blackening resistance. Zinc flowers are mainly produced during the solidification process of zinc. During solidification, the growth of dendrites conflicts with the nucleation of the liquid nucleus of liquid zinc, which determines the grain size of the entire crystal structure formed subsequently. When the zinc layer is solidified, the dendritic growth is the main growth mechanism compared to the nucleation of the crystal nucleus, thus affecting the amount of zinc flower produced. The growth of zinc flower takes a certain time. If the cooling rate of zinc in the solidification process is faster, the zinc flower size is usually smaller. Conversely, if the cooling rate is slower, the zinc flower size is larger. In addition, there are other factors affecting the size of the zinc flower, such as the thickness of the coil, the surface roughness and the cleanliness, which will affect the zinc flower size of the zinc layer formed by the subsequent hot dip galvanizing.

Since hot dip galvanized steel coils have been widely used in automotive sheet metal and structural parts, computer casings, and LCD panels, automotive manufacturers, computer casing processors, and LCD panel manufacturers have improved surface quality for hot dip galvanized steel coils. The higher the requirements. For example, the depot requirements for the size of the zinc flower are, for example, only a fine zinc-rolled steel coil having a size of 0.5 mm to 5 mm, or even a zinc-free steel coil having a zinc flower size of less than 0.5 mm (not visible to the naked eye). However, in general, the continuous hot dip galvanizing line can only produce fine zinc flower steel coils without the arrangement of fine zinc flower equipment, and cannot produce zinc-free steel coils.

The main way to reduce the size of the zinc flower is to increase the nucleation point per unit area of the coil or increase the cooling rate. The purpose of increasing the nucleation point per unit area is to allow many crystals to grow simultaneously in the same region, thereby suppressing each other, so that the zinc flower solidifies when it is not growing, thereby refining the zinc flower. The aforementioned cooling rate at which the zinc layer is solidified is controlled by controlling the growth time of the zinc flower so that the zinc layer is completely solidified while still being fine.

Further, a method of manufacturing a hot dip galvanized steel coil having a reduced zinc flower size is, for example, by causing a sprayed water or an aqueous solution to pass through a mesh high-voltage electric electrode to cause droplets passing through the electrode to adhere to the surface of the steel sheet. Become the solidified core of molten zinc. However, the above method not only increases the cost of electricity, but also has the problem of contaminating the zinc tank equipment. What is more, since the high-pressure jet droplets impinge on the molten zinc layer, the surface of the steel sheet may be dented, which may cause a problem of deterioration in the appearance quality of the zinc layer.

In addition, there is also a conventional method of installing a mobile air bellows in the original process equipment, by moving up and down on both sides of the steel plate, so that the nozzle of the mobile air bellows is precisely aligned with the solidification position of the zinc flower in the steel plate. To accelerate the solidification of zinc flowers and refine the size of zinc flowers. However, this method requires the installation of new equipment, and the mobile air bellows will also have equipment maintenance problems, which will inevitably increase the equipment cost.

In view of the above, it is not necessary to provide a method for manufacturing a hot dip galvanized steel coil, which can increase the size of the zinc flower by increasing the nucleation point per unit area of the steel coil in a process without additional equipment. efficacy.

Accordingly, it is an aspect of the present invention to provide a method of manufacturing a hot dip galvanized steel coil by using a hard abrasive brush roll and controlling the drive current of the hard abrasive brush roll to change the surface microstructure of the coil. To increase the nucleation point per unit area of the coil.

According to an aspect of the present invention, a method of manufacturing a hot dip galvanized steel coil is provided. The above method comprises providing a cold rolled steel coil, a pre-cleaning step, an electrolytic cleaning step, and a hot dip galvanizing step. The pre-cleaning step first performs a first lye cleaning operation on the cold-rolled steel coil, followed by a first rinsing operation in the lye scrubbing tank to obtain a pre-cleaned cold-rolled steel coil. The first brushing operation is performed by a brush roller/back roller, which is a hard abrasive brush roller. The hard abrasive brush roller has a drive current of 1A to 6A.

Next, the pre-cleaned cold-rolled steel coil is subjected to an electrolytic cleaning step to obtain a cleaned cold-rolled steel coil. The electrolytic cleaning step sequentially performs a second lye cleaning operation, an electrolytic cleaning operation and a second brushing operation on the pre-cleaned cold-rolled steel coil. The second brushing operation is carried out in a hot water brushing tank and is carried out by a brushing roller/backing roller which is a hard abrasive brush roller. The hard abrasive brush roller has a drive current of 1A to 6A. Then, the cold-rolled steel coil is subjected to a hot dip galvanizing step to obtain a hot dip galvanized steel coil.

According to an embodiment of the present invention, the cold-rolled steel coil has a relief strength of 110 MPa or more, a tensile strength of 260 MPa or more, and an elongation of 10% or more.

According to an embodiment of the present invention, the cold rolled steel coil has a thickness of 0.2 mm to 3.0 mm and a width of 700 mm to 2030 mm.

According to an embodiment of the present invention, the first lye cleaning operation and the second lye cleaning operation are performed in an alkali solution tank, respectively, and the temperature of the alkali solution tank is 50 ° C to 90 ° C.

According to an embodiment of the invention, the hard abrasive material of the hard abrasive brush roll is selected from the group consisting of carbides, tellurides, oxides, and any combination thereof.

According to an embodiment of the present invention, one of the hot dip galvanized steel coils comprises 0.01% to 1.00% of iron, 0.10% to 1.00% of aluminum, less than 0.05% of unavoidable impurities, and the remaining component is zinc. .

According to an embodiment of the present invention, the composition of the cold-rolled steel coil comprises 0.001% to 0.250% carbon, 0.01% to 2.50% manganese, 0.001% to 0.100% phosphorus, 0.001% to 0.020% sulfur, 0.001% to 0.500% bismuth, 0.00% to 1.00% chromium, 0.00% to 0.50% molybdenum, 0.001% to 0.100% aluminum, 0.000% to 0.010% nitrogen, 0.000% to 0.050% bismuth, 0.000% to 0.050% Vanadium, 0.000% to 0.060% titanium, 0.0000% to 0.0050% boron, 0.00% to 0.10% copper, 0.00% to 0.10% nickel, and the balance iron.

According to an embodiment of the invention, the pre-cleaning step further comprises, after the first brushing operation, performing a first water washing operation and a first drying operation on the cold-rolled steel coil.

According to an embodiment of the invention, the cleaning step further comprises, after the second brushing operation, performing a second water washing operation and a second drying operation on the pre-cleaned cold-rolled steel coil.

According to an embodiment of the present invention, the hot dip galvanized steel coil has a zinc flower size of 0.55 mm or less.

According to the manufacturing method of the hot dip galvanized steel coil of the present invention, the brushing operation is performed by the brushing roller/back roller respectively in the pre-cleaning step and the electrolytic cleaning step, and the brush roller is a hard abrasive brush roller, and the hard abrasive is controlled. The driving current of the brush roller is used to increase the nucleation point per unit area of the hot dip galvanized steel coil in the process of not requiring additional configuration of the refining zinc flower device, thereby achieving the effect of refining the zinc flower.

100‧‧‧ method

110‧‧‧ Providing cold rolled steel coils

120‧‧‧Pre-cleaning the cold-rolled steel coil to obtain pre-cleaned cold-rolled steel coil

121‧‧‧First lye cleaning operation

123‧‧‧First brushing operation

125‧‧‧First washing operation

127‧‧‧First drying operation

130‧‧‧ Electrolytic cleaning of pre-cleaned cold-rolled steel coils to obtain cleaned cold-rolled steel coils

131‧‧‧Second lye cleaning operation

133‧‧‧Electrolysis cleaning operation

135‧‧‧Second brushing operation

137‧‧‧Second washing operation

139‧‧‧Second drying operation

140‧‧‧ Hot-dip galvanizing step for cleaning cold-rolled steel coils to obtain hot-dip galvanized steel coils

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; Part of the flow chart of the manufacturing method of the roll.

FIG. 1B is a partial flow chart showing a pre-cleaning step according to an embodiment of the present invention.

1C is a partial flow chart showing an electrolytic cleaning step according to an embodiment of the present invention.

Fig. 2A is a scanning electron micrograph showing a hot dip galvanized steel coil of Example 1 of the present invention.

Fig. 2B is a scanning electron micrograph showing a hot dip galvanized steel coil of Example 2 of the present invention.

Fig. 2C is a scanning electron micrograph showing a hot dip galvanized steel coil of Example 3 of the present invention.

Fig. 2D is a scanning electron micrograph showing a hot dip galvanized steel coil of Comparative Example 1 of the present invention.

In view of the above, the present invention provides a method of making a hot dip galvanized steel coil. The method comprises a pre-cleaning step and an electrolytic cleaning step on the cold-rolled steel coil, followed by a hot dip galvanizing step to obtain a hot dip galvanized steel coil having a smaller zinc flower size.

Referring to FIG. 1A, a flow chart of a method 100 for manufacturing a hot dip galvanized steel coil according to an embodiment of the present invention is shown. First, in step 110, a cold rolled steel coil is provided. In one embodiment, the composition of the cold rolled steel coil comprises 0.001% to 0.250% carbon, 0.01% to 2.50% manganese, 0.001% to 0.100% phosphorus, 0.001% to 0.020% sulfur, 0.001% to 0.500%.矽, 0.00% to 1.00% chromium, 0.00% to 0.50% molybdenum, 0.001% to 0.100% aluminum, 0.000% to 0.010% nitrogen, 0.000% to 0.050% bismuth, 0.000% to 0.050% vanadium 0.000% to 0.060% of titanium, 0.0000% to 0.0050% of boron, 0.00% to 0.10% of copper, 0.00% to 0.10% of nickel, and the balance of iron. In another embodiment, the cold rolled steel coil has a thickness of from 0.2 mm to 3.0 mm and a width of from 700 mm to 2030 mm. In one embodiment, the cold rolled steel coil has a relief strength of 110 MPa or more, a tensile strength of 260 MPa or more, and an elongation of 10% or more, wherein the cold rolled steel coil preferably has a tensile strength of 140 MPa to 300 MPa, and the tensile strength is preferably It is 260 MPa to 420 MPa, and the elongation is preferably 30% or more.

Next, in step 120, the cold-rolled steel coil is subjected to a pre-washing step to obtain a pre-cleaned cold-rolled steel coil. In one embodiment, the coil tension is between 0.1 metric tons and 5.0 metric tons during the pre-cleaning step. If the tension is too small, for example, less than 0.1 metric ton, the steel coil is liable to be loosened, thereby damaging the peripheral equipment; if the tension is set too large, for example, more than 5.0 metric tons, the steel coil is easily deformed, and defects such as side waves or medium waves are generated. In one embodiment, the pre-cleaning step includes performing a plurality of operations, as described below in connection with FIG. 1B.

Please refer to FIG. 1A and FIG. 1B simultaneously. FIG. 1B is a flow chart showing a pre-cleaning step 120 according to an embodiment of the invention. The pre-cleaning step 120 of Figure 1A is followed by a step 121 of performing a first lye cleaning operation on the cold rolled steel coil. In one embodiment, the first lye cleaning operation is performed in an lye tank, which is provided with a set of decant rolls before and after the lye tank, and a set of immersion rolls are arranged between the skeinsing rolls, wherein The wringer is used to remove residual lye and moisture from the surface of the coil. In one embodiment, the temperature of the lye bath is controlled to be between 50 ° C and 90 ° C. In another embodiment, the lye tank has a lye concentration of from about 0.5% to about 2.0% by weight.

Next, after step 121, step 123 is performed to perform a first brushing operation on the cold rolled steel coil. In one embodiment, the first brushing operation is performed in a lye cleaning bath with a multiple array of brush/back rolls. For example, four sets of scrubbing rolls/back rolls can be provided in the lye washing tank. In one example, a plurality of (eg, two sets) of stranding rolls are optionally disposed in the lye washing tank after the scrubbing roll/back roll to remove lye and moisture from the surface of the coil. In one embodiment, the scrubbing roller is a hard abrasive brush roller to remove surface impurities from the coil. In another embodiment, the hard abrasive material of the hard abrasive brush roll is selected from the group consisting of carbides, tellurides, oxides, and any combination thereof. Compared with the conventional brush roller using nylon, only the surface of the steel coil can be cleaned. The hard abrasive brush roller of the present invention can simultaneously increase the roughness of the surface of the steel coil, so that the nucleation per unit area of the surface of the steel coil The point is increased to achieve the effect of refining the zinc flower.

In the embodiment of the present invention, the first brushing operation by the brush roller/back roller combined with the hard abrasive brush roller can effectively increase the nucleation point on the unit area of the steel coil during the subsequent hot dip galvanizing. The back roll of the present invention can be used to support the steel coil, and the steel coil is more stable when passing through the lye cleaning tank, thereby avoiding steel, as compared with the conventional brushing operation using a scrubbing roll (soft roll)/brushing roll (soft roll). The roll is shaken up and down. In one embodiment, the hard abrasive brush roll has a drive current of 1A to 6A for controlling the gap between the brush roll and the coil and the rotational speed of the hard abrasive brush roll. When the current is larger, the greater the brushing degree of the steel coil, the higher the surface roughness of the steel coil, and the more nucleation points can be generated on the surface area of the steel coil surface, the more the zinc flower refinement degree becomes more obvious. However, if the current is greater than 6A, the surface of the coil may be worn and the appearance of the surface of the coil may be damaged. If the current is less than 1 A, the roughness of the surface of the coil is not significantly increased, which is insufficient to effectively refine the zinc flower.

In addition, the driving current of the hard abrasive brush roller is obtained according to the following formula (1), where W _S represents the width of the coil, V _C represents the line speed, and R represents the adjustment parameter, which is based on the value set by the instrument. change. In one embodiment, the line speed is from 30 m to 180 m per second.

After step 123, step 125 and step 127 are selectively performed. In step 125, the cold-rolled steel coil is wound in a water washing tank to perform a first water washing operation. In one embodiment, the first water washing operation utilizes a complex array of stranding rolls (eg, three sets) to remove residual lye and moisture from the surface of the coil. After step 125, step 127 is selectively performed to perform the first drying operation. In one embodiment, the first drying operation utilizes a dryer to dry the steel coil.

Referring to FIG. 1A, after step 120, step 130 is performed to perform an electrolytic cleaning step on the pre-cleaned cold-rolled steel coil to obtain a cleaned cold-rolled steel coil. In one embodiment, the coil tension is between 0.1 metric tons and 5.0 metric tons during the cleaning step. If the tension is too small, for example, less than 0.1 metric ton, the steel coil is liable to slack and damage the peripheral equipment; if the tension is set too large, for example, more than 5.0 metric tons, the steel coil is easily deformed to cause side waves or medium waves. In one embodiment, the cleaning step includes performing a plurality of operations, which are described below in conjunction with FIG. 1C.

Please refer to FIG. 1A and FIG. 1C simultaneously. FIG. 1C is a flow chart showing an electrolytic cleaning step 130 according to an embodiment of the invention. The electrolytic cleaning step 130 of Figure 1A begins with step 131 and performs a second lye cleaning operation. In one embodiment, the second lye cleaning operation is performed in an lye tank, which is provided with a set of decant rolls before and after the lye tank, and a set of immersion rolls are arranged between the skeinsing rolls, wherein The wringer is used to remove residual lye and moisture from the surface of the coil. In one embodiment, the temperature of the lye bath is controlled to be between 50 ° C and 90 ° C. In another embodiment, the lye tank has a lye concentration of from about 0.5% to about 2.0% by weight. In one embodiment, the temperatures of the lye baths of the first lye cleaning operation and the second lye cleaning operation may be the same or different. In another embodiment, the lye concentration of the lye tank of the first lye cleaning operation and the second lye cleaning operation may be the same or different.

After step 131, step 133 is performed, an electrolytic cleaning operation, which is carried out in an electrolytic cleaning tank. In one embodiment, the electrolytic cleaning tank is provided with, for example, a set of stranding rolls at the front end, and, for example, two sets of stranding rolls at the rear end, and a immersion roll between the front end and the rear end of the stranding rolls. In other words, the steel coil enters the electrolytic cleaning tank, and the steel coil passes through the squeezing roller, passes through the immersion roller, and then passes through the squeezing roller. In one embodiment, for example, two sets of rectifiers are provided in front of and behind the immersion roller to control the electrolysis current.

Next, in step 135, a second brushing operation is performed on the pre-cleaned cold-rolled steel coil after the electrolytic cleaning operation. The second scrubbing operation is carried out in a hot water scrubbing tank with a multi-array scrubbing/backing roll. For example, four sets of scrubbing rolls/back rolls can be provided in the hot water washing tank. In one example, a plurality of (eg, two sets) of stranding rolls are optionally disposed in the hot water scrubbing tank after the scrubbing/backing rolls to remove lye and moisture from the surface of the coil. In one embodiment, the scrubbing roller is a hard abrasive brush roller to remove surface impurities from the coil. In another embodiment, the hard abrasive material of the hard abrasive brush roll is selected from the group consisting of carbides, tellurides, oxides, and any combination thereof. Compared with the conventional brush roller using nylon (cleaning the surface of the steel coil alone), the use of the hard abrasive brush roller of the present invention can simultaneously increase the roughness of the surface of the steel coil, so that the nucleation point per unit area of the surface of the steel coil Increase to achieve the effect of refining zinc flowers.

In the embodiment of the present invention, the second brushing operation by the brush roller/back roller combined with the hard abrasive brush roller can effectively increase the nucleation point on the unit area of the steel coil after the hot dip galvanizing. Compared with the conventional brushing operation using a scrubbing roller (soft roller)/brushing roller (soft roller), the back roller of the present invention can be used to support the steel coil, and the steel coil is more stable when passing through the hot water scrubbing tank, thereby avoiding steel. The roll is shaken up and down. In one embodiment, the hard abrasive brush roll has a drive current of 1A to 6A for controlling the gap between the brush roll and the coil and the rotational speed of the hard abrasive brush roll. When the current is larger, the greater the brushing degree of the steel coil, the higher the surface roughness of the steel coil, and the more nucleation points per unit area on the surface of the steel coil, the more obvious the degree of zinc flower refinement. However, if the current is greater than 6A, the surface of the coil may be worn and the appearance of the surface of the coil may be damaged. If the current is less than 1 A, the roughness of the surface of the coil is not significantly increased, which is insufficient to effectively refine the zinc flower.

After step 135, steps 137 and 139 can be selectively performed. In step 137, the pre-cleaned cold-rolled steel coil is wound in a water washing tank for a second water washing operation. In one embodiment, the second water washing operation utilizes a complex array of stranding rolls (eg, three sets) to remove residual lye and moisture from the surface of the coil. After step 137, step 139 is selectively performed to perform a second drying operation. In one embodiment, the second drying operation utilizes a dryer to dry the steel coil.

Referring to FIG. 1A, after step 130, step 140 is performed to perform a hot dip galvanizing step on the cleaned cold rolled steel coil to obtain a hot dip galvanized steel coil. In one embodiment, the hot dip galvanized steel coil coating comprises from 0.01% to 1.00% iron, from 0.10% to 1.00% aluminum, less than 0.05% unavoidable impurities, and the balance being zinc. Using the hot dip galvanized steel coil obtained by the method 100, in the pre-cleaning step 120 and the electrolytic cleaning step 130, the brushing operation is performed by the brush roller/back roller, and the hard abrasive brush roller is used as the brush roller to make the steel The surface of the roll simultaneously achieves the effect of grinding and cleaning. Furthermore, controlling the driving current of the brushing roller can effectively increase the nucleation point per unit area of the surface of the steel coil, thereby effectively refining the surface zinc flower of the hot dip galvanized steel coil. Therefore, the method 100 for manufacturing a hot dip galvanized steel coil of the present invention can be modified in a low-cost process without the addition of a zinc flower refining device, thereby achieving the effect of refining the zinc flower of the hot dip galvanized steel coil.

The following examples are used to illustrate the application of the present invention, and are not intended to limit the present invention. Those skilled in the art can make various changes without departing from the spirit and scope of the present invention. Retouching.

Example 1

A mild steel of GI-SGCD1 is provided, wherein the mild steel of GI-SGCD1 has a tensile strength of 140 MPa to 300 MPa, a tensile strength of 260 MPa to 420 MPa, and an elongation of 30% or more. Example 1 used GI-SGCD1 mild steel having a thickness of 0.7 mm and a width of 895 mm. The method for producing the hot dip galvanized steel coil of the present invention was carried out on the mild steel of GI-SGCD1, and after 4 days from the production of the hot dip galvanized steel coil, the steel coil test piece of Example 1 was sampled. Next, the surface of the steel coil test piece of Example 1 was lightly ground with a sandpaper, and the surface zinc layer was etched with hydrochloric acid for 3 seconds to 20 seconds. Then, the size of the zinc flower was calculated in accordance with the standard specification of ASTM (E112), and the surface topography of the steel coil test piece of Example 1 was observed by a scanning electron microscope as shown in Fig. 2A.

Example 2 and Example 3 and Comparative Example 1

The materials and processes of Example 2 and Example 3 are the same as those of Example 1, except that the number of days of hot-dip galvanized steel coils is produced after using a hard abrasive brush roll, wherein Examples 2 and 3 respectively produce hot dip After galvanizing steel coils for 10 days (about 10,000 metric tons of hot dip galvanized steel coils) and 18 days (about 18,000 metric tons of hot dip galvanized steel coils), the coils were sampled to obtain Example 2 and Steel coil test piece of Example 3. The material and process of Comparative Example 1 were also the same as in Example 1, except that the hard abrasive brush roll was not used, but a steel roll test piece obtained by sampling the steel coil for 10 days after using a conventional nylon brush roll was sampled. In Example 2, Example 3 and Comparative Example 1, the zinc flower size was calculated in the same manner as in Example 1, and the surface topography of the steel coil was also observed by a scanning electron microscope, as shown in Figs. 2B to 2D.

2A to 2C are surface topographs of hot-dip galvanized steel coil test pieces of Examples 1 to 3 of the present invention. Fig. 2D shows the surface topography of the hot dip galvanized steel coil test piece of Comparative Example 1 of the present invention. 2A to 2D, the zinc flower sizes of the surfaces of the hot dip galvanized steel coils of Examples 1 to 3 and Comparative Example 1 were 0.52 mm, 0.47 mm, 0.41 mm, and 0.75 mm, respectively.

From the results of the above examples and comparative examples, it is understood that the use of a hard abrasive brush roller can indeed reduce the size of the zinc flower on the surface of the hot dip galvanized steel coil, and the zinc flower size is reduced by about 30% to about 50%. In theory, the longer the hard abrasive brush roll is used, the more severe the steel roll wear is, the hard abrasive brush roll will gradually reduce the degree of grinding of the steel coil, and the steel roll will be formed on the unit area. The less the nucleation point, the more the surface zinc size of the produced steel coil is increased. However, in the actual production process, the size of the zinc flower is also affected by the cooling effect of the steel coil component, the zinc layer, the cleanliness of the steel coil surface and the surface roughness, etc., and it is not easy to maintain the consistency in each process. . Accordingly, although the zinc flower sizes of Examples 1 to 3 did not increase as the number of days of use of the hard abrasive brush rolls increased, the time for using the hard abrasive brush rolls was 18 days (production of about 18,000 metric tons of steel coils). When it is inside, the zinc flower size on the surface of the steel coil can be refined to 0.55 mm or less, preferably 0.50 mm or less, more preferably 0.40 mm to 0.50 mm.

As described above, the manufacturing method of the hot dip galvanized steel coil to which the present invention is applied can be performed by the brushing roller/back roller, respectively, in the pre-cleaning step and the electrolytic cleaning step, and the hard abrasive brush roller is used. The brush roller is used to increase the nucleation point on the unit area of the steel coil, thereby limiting the growth of the zinc flower and controlling the driving current of the hard abrasive brush roller to control the gap between the brush roller and the steel coil and the rotation speed of the hard abrasive brush roller. The roughness of the surface of the hot dip galvanized steel coil is increased. Therefore, the method for manufacturing the hot dip galvanized steel coil of the present invention can achieve a steel coil having a specific thickness, width, steel type, line speed and plating thickness, and can be finely formed in a process that does not require an additional configuration of the refining zinc flower device. The effect of zinc flower to enhance the quality of the product.

While the invention has been described above in terms of several embodiments, it is not intended to limit the scope of the invention, and the invention may be practiced in various embodiments without departing from the spirit and scope of the invention. The scope of protection of the present invention is defined by the scope of the appended claims.

Claims (10)

 A method for manufacturing a hot dip galvanized steel coil, comprising: providing a cold rolled steel coil; performing a pre-cleaning step on the cold rolled steel coil to obtain a pre-cleaned cold rolled steel coil, wherein the pre-cleaning step comprises: the cold rolled steel Rolling a first lye cleaning operation; and after the first lye cleaning operation, performing a first brushing operation on the cold-rolled steel coil in an lye scrubbing tank, wherein the first brushing operation is performed in plurality The brush/back roll is performed by a plurality of hard abrasive brush rolls, and one of the hard abrasive brush rolls has a driving current of 1A to 6A; and the pre-cleaned cold-rolled steel coil is subjected to a roll An electrolytic cleaning step to obtain a cleaning cold rolled steel coil, wherein the electrolytic cleaning step comprises: performing a second lye cleaning operation on the pre-cleaned cold-rolled steel coil; after the second lye cleaning operation, the pre-cleaning cold Rolling the coil to perform an electrolytic cleaning operation; and after the electrolytic cleaning operation, performing a second brushing operation on the pre-cleaned cold-rolled steel coil in a hot water washing tank, wherein the second brushing operation is performed by a plurality of brushing rollers/ Rolling, the scrubbing rolls are a plurality of hard abrasive brush rolls, and one of the hard abrasive brush rolls has a driving current of 1A to 6A; and the hot-rolled steel coil is subjected to a hot dip galvanizing step to obtain a hot dip Galvanized steel coils.    The method for producing a hot dip galvanized steel coil according to claim 1, wherein the cold rolled steel coil has a relief strength of 110 MPa or more, a tensile strength of 260 MPa or more, and an elongation of 10% or more.    The method for producing a hot dip galvanized steel coil according to claim 1, wherein the cold rolled steel coil has a thickness of one of 0.2 mm to 3.0 mm and a width of one of 700 mm to 2030 mm.    The method for manufacturing a hot dip galvanized steel coil according to claim 1, wherein the first alkali cleaning operation and the second alkali cleaning operation are performed in an alkali solution tank, respectively, and the alkali is used. One of the tanks has a temperature of 50 ° C to 90 ° C.    The method for manufacturing a hot-dip galvanized steel coil according to the first aspect of the invention, wherein the hard abrasive material of the hard abrasive brush roller is selected from the group consisting of carbides, tellurides, oxides, and any combination thereof. Form a group of people.    The method for manufacturing a hot dip galvanized steel coil according to claim 1, wherein the one of the hot dip galvanized steel coils comprises 0.01% to 1.00% of iron, 0.10% to 1.00% of aluminum, less than 0.05. % of the inevitable impurities, and the rest of the ingredients are zinc.    The method for producing a hot dip galvanized steel coil according to the above aspect of the invention, wherein the cold rolled steel coil comprises: 0.001% to 0.250% carbon; 0.01% to 2.50% manganese; 0.001% to 0.100% Phosphorus; 0.001% to 0.020% sulfur; 0.001% to 0.500% bismuth; 0.00% to 1.00% chromium; 0.00% to 0.50% molybdenum; 0.001% to 0.100% aluminum; 0.000% to 0.010% nitrogen 0.000% to 0.050% bismuth; 0.000% to 0.050% vanadium; 0.000% to 0.060% titanium; 0.0000% to 0.0050% boron; 0.00% to 0.10% copper; 0.00% to 0.10% nickel; The rest of the ingredients are iron.    The method for manufacturing a hot-dip galvanized steel coil according to the first aspect of the invention, wherein the pre-cleaning step further comprises: after the first brushing operation, performing a first water washing operation on the cold-rolled steel coil and a first A drying operation.    The method for manufacturing a hot dip galvanized steel coil according to claim 1, wherein the cleaning step further comprises: after the second brushing operation, performing a second water washing operation on the pre-cleaned cold-rolled steel coil and The second drying operation.    The method for producing a hot dip galvanized steel coil according to claim 1, wherein the hot dip galvanized steel coil has a zinc flower size of 0.55 mm or less.