JP2005139518A - Facility and method for manufacturing chemical conversion-treated metal strip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing a chemical conversion-treated metal strip superior in surface appearance while preventing the formation of stain, and to provide a manufacturing method therefor. <P>SOLUTION: In a facility for manufacturing the chemical conversion-treated metal strip provided with a means for supplying a conversion coating liquid to both surfaces of a horizontally threaded metal strip, a pair of top and bottom squeeze rolls for adjusting the amount of an attached conversion coating liquid on the surface of the metal strip by squeezing the conversion coating liquid supplied to both surfaces of the metal strip and a drying device for drying the metal strip from which the conversion coating liquid has been squeezed out, by spraying hot blast to it, the facility for manufacturing the conversion-coated metal strip has such a liquid-storing section as to sink the lower part of the lower squeeze roll in the liquid therein, arranged under the lower squeeze roll contacting with the undersurface of the metal strip. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a chemical conversion metal strip manufacturing facility and a manufacturing method thereof. More specifically, the present invention relates to a manufacturing facility for a chemical conversion-treated metal strip capable of obtaining an excellent surface appearance and a manufacturing method thereof.

  Zinc-based galvanized steel sheets are excellent in corrosion resistance, and are used in various applications in fields such as home appliances and building materials. In order to further improve the corrosion resistance of the galvanized steel sheet or impart properties other than the corrosion resistance, chromate treatment and other chemical conversion treatments are performed.

  The principal part structure of the chemical conversion treatment equipment generally used in order to perform a chemical conversion treatment to the galvanized steel plate passed in a horizontal direction is shown in FIG.

  In FIG. 2, a required chemical conversion solution is sprayed and supplied to both surfaces of a zinc-based plated steel plate 1 that is horizontally passed from the spray device 9 of the chemical conversion treatment tank 2, and adheres to the surface of the zinc-based plated steel plate 1. Excess processing liquid is drawn by a pair of upper and lower squeezing rolls 3 arranged with a galvanized steel sheet sandwiched therebetween, and then the processing liquid is dried by blowing high-temperature air over the entire width of the steel sheet by a drying device 4. The chemical conversion treatment steel plate is manufactured (for example, refer patent document 1).

  When the chemical conversion treatment liquid is sprayed onto the steel sheet with the apparatus shown in FIG. 2, the treatment liquid squeezes unevenly (stain) on the steel sheet surface after passing through the squeeze roll 3, and the appearance of the galvanized steel sheet after the treatment is improved. There is a problem of deteriorating.

The prior art document information is described below.
JP-A-9-137284 (page 3, FIG. 2)

  An object of the present invention is to provide an apparatus and a method for producing a chemical conversion metal strip that can prevent the occurrence of the stain and can produce a chemical conversion treatment metal strip excellent in surface appearance.

Means of the present invention for solving the above-mentioned problems are as follows.
(1) Means for supplying a chemical conversion treatment solution to both surfaces of a metal strip that is passed in a horizontal direction, the chemical conversion treatment solution supplied to both surfaces of the metal strip is squeezed, and a chemical conversion treatment liquid adhesion amount on the surface of the metal strip is reduced. In a production facility for a chemical conversion treatment metal strip comprising a pair of upper and lower squeezing rolls to be adjusted, and a drying device that blows hot air on the metal strip from which the chemical conversion liquid has been squeezed to dry,
A chemical conversion-treated metal strip manufacturing facility, characterized in that a liquid storage part is provided below the lower squeeze roll in contact with the lower surface of the metal strip so that the lower part of the lower squeeze roll is submerged in the liquid.

  (2) The chemical conversion treatment metal strip according to (1), wherein a spray device for spraying a liquid onto the surface of the lower squeeze roll is provided on at least one of the entrance side and the exit side of the squeeze roll. Manufacturing equipment.

  (3) The equipment for producing a chemical conversion metal strip according to (1) or (2), wherein the spray device for spraying the liquid is a water spray device.

  (4) The equipment for producing a chemical conversion metal strip according to any one of (1) to (3), wherein a distance between the squeezing roll and the drying device is 1 m or less.

(5) Means for supplying chemical conversion treatment liquid to both surfaces of a metal strip that is passed in the horizontal direction, chemical conversion treatment liquid supplied to both surfaces of the metal strip is squeezed by a pair of upper and lower squeeze rolls, and then post chemical conversion treatment liquid In the method of producing a chemical conversion-treated metal strip by blowing hot air on the metal strip that has been squeezed and drying it,
A method for producing a chemical conversion-treated metal strip, wherein the lower portion of the lower squeeze roll is immersed in a liquid in a liquid storage section provided under the lower squeeze roll in contact with the lower surface of the metal strip.

  (6) The method for producing a chemical conversion-treated metal strip according to (5), wherein a liquid is sprayed on the surface of the lower squeeze roll on at least one of the entrance side and the exit side of the squeeze roll.

  (7) The method for producing a chemical conversion-treated metal strip according to (5) or (6), wherein the sprayed liquid is water.

  (8) The method for producing a chemical conversion-treated metal strip according to any one of (5) to (7), wherein a distance between the squeezing roll and a drying device is 1 m or less.

  According to the present invention, it is possible to prevent a stain caused by the lower drawing roll. Further, according to the present invention, even if the distance between the squeeze roll and the drying device is short, the occurrence of stain can be prevented, so that the processing equipment length can be shortened and the processing equipment can be made compact.

  Embodiments of the present invention will be described below. The present inventors have examined and investigated various causes and preventive measures for the occurrence of stains that occur when a galvanized steel sheet is subjected to chemical conversion treatment. As a result, the following matters became clear.

  Stain is likely to occur in equipment where the distance between the squeeze roll and the dryer (distance between the axis of the squeeze roll and the inlet side of the dryer) is 1 m or less, especially when the steel strip is thick at the bottom edge of the steel strip. It tends to occur on the side.

The reason for the occurrence of stain was estimated as follows.
(I) When the steel strip is thick, the squeezing effect on the steel strip end side is increased due to the deflection of the squeezing roll, and therefore, the steel strip end side tends to be a thin film compared to the central portion on the drawing roll exit side.
(Ii) Since the upper surface of the steel strip is open between the squeeze roll and the drying device, the high temperature air that flows upstream from the drying device easily flows out of the system, whereas the lower surface of the steel strip Then, since there are a chemical conversion treatment tank, a squeeze roll base, etc. upstream, high-temperature air is unlikely to flow out of the system, so the atmosphere in the vicinity of the lower squeeze roll tends to be hotter. When the squeeze roll and the drying device are close to each other, the above tendency becomes more remarkable.
(Iii) The treatment liquid adhering to the steel strip surface is squeezed out by a squeeze roll. The treatment liquid supplied to the lower surface of the steel strip falls directly downward from the surface of the steel strip before reaching the squeeze roll, and the amount of liquid squeezed out by the squeeze roll is reduced. For this reason, the meniscus formation at the squeezed part becomes unstable in the lower squeeze roll, and therefore the flow of the processing liquid flowing down along the surface of the lower squeeze roll becomes uneven in the width direction of the steel strip, and the surface of the lower squeeze roll becomes wet. The state becomes insufficient.

  A certain amount of treatment liquid is adhered to the surface of the squeeze roll immediately after squeezing the treatment liquid. In a place where the film thickness is thin or where meniscus formation is insufficient between the rotation of the squeezing roll and the next squeezing of the processing liquid, drying of the processing liquid adhering to the surface of the lower squeezing roll is promoted. As a result, the viscosity increases. The portion where the viscosity is increased due to the concentration is more prominent by repeatedly rotating the squeeze roll to squeeze the treatment liquid. When the processing liquid is squeezed out with a squeezing roll having a portion to which a concentrated processing liquid with high viscosity is attached, it is considered that the portion is transferred to the surface of the steel strip and stain is generated on the surface of the steel strip.

  In order to prevent the occurrence of stain, it was considered effective to prevent the treatment liquid from concentrating on the surface of the lower squeeze roll to increase the viscosity. Therefore, various studies were made on means for preventing the treatment liquid from concentrating on the surface of the lower drawing roll, and the present invention was completed.

  FIG. 1 is a view for explaining a main part of a chemical conversion metal strip manufacturing apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a galvanized steel sheet, 2 is a chemical conversion treatment tank, 3 is a squeeze roll, 4 is a drying device, 5 is a storage tank (storage part), 6a is a squeeze roll entry side spray device, and 6b is a squeeze roll exit. A side spray device, 7 is a chemical conversion liquid circulation tank, 8 is a pump, and 9 is a spray apparatus (for chemical conversion liquid).

  The squeeze roll 3 includes an upper squeeze roll 3a and a lower squeeze roll 3b, and a storage tank 6 is provided below the lower squeeze roll 3b. A spray device 6a for spraying water on the surface of the lower squeeze roll 3b is provided on the inlet side of the lower squeeze roll 3b, and a spray device 6b for spraying water on the surface of the lower squeeze roll 3b is provided on the outlet side of the lower squeeze roll 3b. .

  The treatment liquid in the chemical conversion liquid circulation tank 7 is pressurized by the pump 8 and sprayed onto both surfaces of the steel strip 1 from the spray device 9 in the chemical conversion treatment tank 2 through the pipe 13. The processing liquid flowing down in the chemical conversion treatment tank 2 returns to the chemical conversion treatment liquid circulation tank 7 through the drain pipe 14. The processing liquid adhering to both surfaces of the steel strip 1 is squeezed out by the squeezing roll 3. The processing liquid squeezed by the squeezing roll 3 flows into the storage tank 5.

  The water sprayed from the inlet spray device 6a to the lower squeeze roll 3b is squeezed by the squeeze roll 3 and then flows along the surface of the roll 3b, or immediately flows along the surface of the roll 3b, 5 flows into. The spray water sprayed from the outlet side spray device 6 b to the lower squeeze roll 3 b flows down the surface of the roll 3 b and flows into the storage tank 5.

  An overflow pipe 12 is installed near the upper edge of the storage tank 5, and a drain pipe 16 is installed at the bottom of the storage tank 5. By closing the valve 17 provided in the drain pipe 16, the liquid in the storage tank 5 is configured to be sent to the chemical conversion circulation tank 7 through the overflow pipe 12, and the lower squeeze roll 3 b is stored in the lower part. It is comprised so that it may be immersed in the liquid in the tank 5. FIG.

  In the chemical treatment tank circulation tank 7, the treatment liquid concentration is managed within a predetermined concentration range, and when the concentration is outside the concentration range, a high concentration treatment liquid is replenished from a replenishment tank (not shown) or water is replenished from a water pipe. The density is adjusted.

  In the drying device 4, two sets of nozzle headers 15 for injecting high-temperature heated air above and below the steel strip are arranged above and below the steel strip 1 through plate direction.

  The effect of preventing the occurrence of stain due to the lower squeeze roll is also achieved by providing a spray device on either the metal band entrance side or the exit side, but from the viewpoint of enhancing the effect of preventing the occurrence of stain The spray device is preferably provided on both the metal band entrance side and the exit side of the squeeze roll as in the device of FIG.

Chemical conversion treatment is performed as follows using this apparatus.
The treatment liquid in the chemical conversion liquid circulation tank 7 is pressurized by the pump 8 and is sprayed to both surfaces of the steel strip 1 from the spray device 9 in the chemical conversion treatment tank 2 through the pipe 13. The processing liquid flowing down in the chemical conversion treatment tank 2 returns to the chemical conversion treatment liquid circulation tank 7 through the drain pipe 14. The treatment liquid adhering to both surfaces of the steel strip 1 is squeezed out by the squeezing roll 3.

  In the squeeze roll 3, water is sprayed from the spray devices 6a and 6b onto the surface of the lower squeeze roll 3b. The processing liquid squeezed by the squeezing roll 3 flows into the storage tank 5. The water sprayed from the spray devices 6a and 6b also flows into the storage tank 5. The liquid flowing into the storage tank 5 overflows from the overflow pipe 12 and flows to the chemical conversion liquid circulation tank 7. In the storage tank 5, the lower squeezing roll 3b lower part rotates while being immersed in the liquid.

  Thus, when the squeezing roll 3 is rotated to squeeze the processing liquid, it is prevented that the processing liquid is concentrated on the surface of the lower squeezing roll 3b and the viscosity is increased.

  The steel strip 1 that has passed through the squeezing roll 3 is dried by a downstream drying device 4. The chemical conversion treated steel plate manufactured as described above has no stain due to the lower drawing roll 3b.

  Since the spray water of the spray devices 6a and 6b flows into the storage tank 5, the concentration of the processing liquid stored here decreases. The treatment liquid having a reduced concentration overflows from the storage tank 5 and flows into the chemical conversion liquid circulation tank 7. A high-concentration treatment liquid is replenished into the chemical conversion liquid circulation tank 7 from a replenishment tank (not shown) so that the concentration of the treatment liquid in the chemical conversion liquid circulation tank 7 does not deviate from a predetermined management range.

  In order to suppress the replenishment of the high-concentration processing liquid as much as possible, it is desirable to reduce the decrease in the processing liquid concentration in the storage tank 5 as much as possible within a range where the occurrence of stain can be prevented. From such a viewpoint, it is preferable to reduce the amount of sprayed water of the spray devices 6a and 6b as much as possible, and for the thick material size where stains are likely to occur, the amount of sprayed water is increased so that the flow rate on the steel strip end side is larger than that on the central side. It is also advantageous to adjust accordingly. Further, the flow rate of the processing liquid adhered to the steel strip 1 or the amount of processing liquid inevitably taken out of the circulation system between the chemical conversion liquid circulation tank 7 and the chemical conversion tank 2 is investigated in advance, and the spray device It is also advantageous to adjust the amount of water sprayed on 6a and 6b to be as low as possible or close to that range.

  In addition, the present invention provides a chemical conversion treated steel sheet in an apparatus in which the distance between the squeeze roll and the drying apparatus (distance between the squeeze roll axis and the drying apparatus; dimension L in FIG. It is suitable as an apparatus for manufacturing.

  In the said apparatus, although water was sprayed on the surface of the lower drawing roll, it is also possible to spray a chemical conversion liquid instead of water. In this case, the chemical conversion treatment solution concentration may be a chemical conversion treatment solution used in circulation, or may be a dilution of this chemical conversion treatment solution.

  The chemical conversion treatment liquid targeted by the present invention is not particularly limited. A chromate treatment solution, a chromium-free treatment solution, or a treatment solution containing an organic resin or the like in the treatment solution may be used. Moreover, you may form the film | membrane used as an upper layer, after processing using the said chemical conversion liquid.

  As mentioned above, although embodiment of this invention was described for galvanized steel plate, even if it is metal strips other than galvanized steel plate, the effect of this invention is show | played.

A reactive chromate treatment is performed on an electrogalvanized steel sheet with a size of 0.8 x 914 mm (adhesion amount of 20/20 g / m ² ) at a passing speed of 50 mpm to form a chromate film of approximately 18 mg / m ^{2 in} terms of metallic chromium. Then, using the apparatus shown in FIG. 1, a chemical treatment tank using a chromate treatment liquid (temperature 60 ° C.) having a total Cr concentration of 1% and Cr ⁶⁺ / Cr ³⁺ = ^3/1 as the chemical treatment liquid. 2 was subjected to sealing treatment (the amount of chromium adhesion was about 3 mg / m ^{2 in} terms of metal chromium), the treatment liquid was squeezed out with a squeeze roll 3, and the treatment liquid was dried with a drying device 4 to obtain a chromate-treated steel sheet.

  As the spray devices 6a and 6b, those capable of spraying on the full width of the steel plate were installed. At that time, the usage conditions of the storage tank 5 under the lower squeeze roll 3b and the usage conditions of the spray devices 6a and 6b were variously changed. The usage conditions (presence / absence of immersion) of the storage tank 5 were adjusted by opening or closing the valve 17 of the drain pipe 16. The distance L between the squeezing roll 3 and the drying device 4 is about 500 mm.

Moreover, the steel plate surface appearance after a process was observed visually, and the presence or absence of the stain was evaluated as follows.
Stain rating:
○: Stain is not generated.
Δ: Slight occurrence of stain
X: Clear stain generation.

  Table 1 shows the use conditions of the storage tank 5 (presence / absence of immersion), the use conditions of the spray devices 6a and 6b (presence / absence of spray), and the evaluation results of the stain.

  Table 1 shows the following. It can be seen that the example of the present invention is more effective in preventing the occurrence of stain than the conventional example and the comparative example. When the lower squeezing roll lower part is immersed in the liquid in the storage tank 5 and the spray devices 6a and 6b are used, the effect of preventing stain is more excellent.

  INDUSTRIAL APPLICABILITY The present invention can be used for producing a chemical conversion-treated metal strip excellent in surface appearance.

It is a figure explaining the principal part of the chemical conversion treatment metal strip manufacturing apparatus which concerns on embodiment of this invention. It is a figure which shows the principal part structure of the chemical conversion treatment equipment generally used in order to give a chemical conversion treatment to the zinc-plated steel plate passed in a horizontal direction.

Explanation of symbols

1 Steel strip (galvanized steel sheet)
2 Chemical conversion treatment tank 3 Drawing roll 4 Drying device 5 Storage tank (storage part)
6a, 6b Spray device 7 Chemical conversion liquid circulation tank 8 Pump 9 is a spray device (for chemical conversion liquid)
11 Water pipe 12 Overflow pipe 13 Pipe 14, 16 Drain pipe 15 Nozzle header 17 Valve

Claims (8)

Means for supplying chemical conversion treatment liquid to both surfaces of a metal strip that is passed in a horizontal direction, and adjusting the amount of chemical conversion liquid adhesion on the surface of the metal strip by squeezing the chemical conversion liquid supplied to both surfaces of the metal strip In a production facility for a chemical conversion treatment metal strip comprising a pair of squeezing rolls and a drying device that blows hot air on the metal strip from which the chemical conversion liquid has been squeezed and dried,
A production facility for a chemical conversion treated metal strip, characterized in that a liquid storage part is provided below the lower squeeze roll in contact with the lower surface of the metal strip so that the lower part of the lower squeeze roll is submerged in the liquid. 2. The chemical conversion metal strip manufacturing facility according to claim 1, wherein a spray device that sprays liquid onto the surface of the lower squeeze roll is provided on at least one of the squeezing roll on the metal strip entry side and the exit side. . The apparatus for producing a chemical conversion treatment metal strip according to claim 1 or 2, wherein the spray device for spraying the liquid is a water spray device. The distance between the squeezing roll and the drying device is 1 m or less, The chemical conversion treatment metal strip manufacturing facility according to any one of claims 1 to 3. Means for supplying chemical conversion treatment liquid to both surfaces of a metal strip that is passed in the horizontal direction, the chemical conversion treatment liquid supplied to both surfaces of the metal strip is squeezed by a pair of upper and lower squeezing rolls, and the chemical conversion treatment liquid is then squeezed out. In a method of producing a chemical conversion-treated metal strip by blowing hot air on the obtained metal strip and drying it,
A method for producing a chemical conversion-treated metal strip, wherein the lower portion of the lower squeeze roll is immersed in a liquid in a liquid storage section provided under the lower squeeze roll in contact with the lower surface of the metal strip. 6. The method for producing a chemical conversion-treated metal strip according to claim 5, further comprising spraying a liquid onto the surface of the lower drawn roll on at least one of the metal roll entering and exiting side of the drawn roll. The method for producing a chemical conversion-treated metal strip according to claim 5 or 6, wherein the sprayed liquid is water. The method for producing a chemical conversion-treated metal strip according to any one of claims 5 to 7, wherein a distance between the squeezing roll and a drying device is 1 m or less.

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