JPS6350424B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a molten metal plated steel sheet with a concavo-convex pattern having a clear concavo-convex pattern and excellent uniformity of gloss at the convex portions. A steel plate with an uneven pattern is a steel plate having a three-dimensional pattern formed by partially indenting the surface of the steel plate with a depth of about 5 to 300 μm for the main purpose of decoration. This type of steel plate is required to have excellent corrosion resistance as a decorative steel plate, so it is generally used with molten metal plating (hereinafter simply referred to as molten metal plating) for rust prevention. When a patterned steel plate is hot-dipped, the difference in height between the concave and convex portions is reduced by the adhered matte metal, making it difficult to obtain a decorative effect through the contrast of the concave and convex portions, so it has not been widely used. However, recently, a method of adjusting the thickness of the plating layer using gas injection during melt plating has made it possible to equalize the thickness of the plating layer on concave and convex portions. It has now become possible to obtain a steel plate with relatively good contrast without deterioration. However, if the plated metal is solidified after melting a steel plate with an uneven pattern, the first
As shown in the figure, in the plated metal 1, the corner 3 of the steel plate convex part 2 is rounded, so the outline of the convex part formed by the corner becomes unclear, and the contrast as a patterned steel plate becomes weak. There's a problem. In this case, if a concave-convex pattern with a large height difference is applied, the decorative effect will not be significantly impaired even if the contour of the convex part becomes a little unclear due to the plating metal, but the difference in the concave-convex height difference (the depth of the concave part) will be 10 thick
(If it exceeds about 15%,
(Cracks occur during embossing rolling), and when the plate thickness is thin, for example, the unevenness height difference of a 0.4 mm steel plate is 0.03 ~
If it is only about 0.04 mm and the contour of the convex part becomes unclear, the contrast of the concave and convex pattern will be significantly reduced.
It becomes impossible to obtain the desired decorative effect. As a countermeasure to this problem, it is possible to make the contours of the convex parts clearer by rolling down the surface of the plated steel plate with a skin pass roll and flattening the plating layer on the upper surface of the convex parts. As shown, the convex portion 2
The thickness of the plating metal 1 on the top surface is not uniform, and there are variations in thickness, so even if the thick part can be flattened by rolling down with a roll, the thin part is not rolled down and remains rounded. Therefore, the goal cannot be achieved. Furthermore, since there is a difference in gloss between the areas that have been rolled and the areas that have not, the appearance may be impaired due to uneven gloss. In addition, if the skin pass rate is increased, the thin parts of the plated metal will also be rolled down, which will eliminate uneven gloss and make the outline of the convex parts clearer, but on the other hand, the rolling force of the roll will be concentrated on the convex parts. As a result, the convex portions are plastically deformed and crushed, and the contrast due to the height difference between the convex and convex portions is diminished, making it impossible to achieve the original purpose of the patterned steel plate. Therefore, there is a need for a means to reduce the roundness of the protrusions and sharpen the pattern by plastically flowing only the glazing coating attached to the surface of the protrusions without plastically deforming the steel plate base of the protrusions. The present invention provides a method for producing a hot-dip galvanized steel sheet with an uneven pattern that eliminates the above-mentioned drawbacks. The feature is that after hot-dipping a cold-rolled steel plate with an uneven pattern, or after performing an alloying treatment following that, the surface of the steel plate without an uneven pattern is
The upper surface of the convex portion is supported by a support roll made of metal or a metal shaft with rubber lining, and the surface with the uneven pattern is rolled down by a metal reduction roll with a smaller diameter than the support roll. The purpose is to plastically deform and smooth the plated metal.
That is, in the present invention, a molten steel plate with an uneven pattern is passed through a rolling device consisting of a support roll having a relatively large diameter and a reduction roll having a smaller diameter than the support roll, and the pattern-free surface ( The surface with a pattern (hereinafter also referred to as the "front surface") is brought into contact with a large-diameter support roll to disperse the rolling stress of the roll and avoid plastic deformation of the steel plate. ) is brought into contact with a small-diameter rolling roll to locally concentrate the rolling force, thereby plastically deforming only the plated metal on the top surface of the convex part, and as shown in Figure 2, the plated metal on the top surface of the convex part 2 is 1 is smoothed and the roundness of its corners is eliminated. FIG. 3 is a schematic side view showing a specific example of the rolling down device used in the present invention. 11 is a support roll, 1
2 is a reduction roll facing the support roll,
The support roll 11 has a relatively large diameter and the reduction roll has a smaller diameter than the support roll. In addition,
Since the purpose of the present invention is to plastically deform only the plated metal by rolling down the rolls, the rolls are made of a material that is harder than the plated metals such as zinc or aluminum, as well as commonly used steel or cast steel. Any metal can be used as long as it has a high deformation resistance. After the uneven patterned steel sheet S is melt-sealed by a conventional method or subjected to a subsequent alloying treatment, it is moved to a roll 1 rotated by a driving means (not shown).
Between 1 and 12, the back side is placed on the support roll 11,
The front side is brought into contact with the reduction roll 12, respectively, and the sheet is threaded. In order to avoid plastic deformation of the steel plate S itself, the reduction by the rolls 11 and 12 must not be a strong reduction that reduces the thickness of the steel plate by 0.5 to 5% as in a normal skin pass mill, and is relatively low. It is necessary to have a rolling force. In the above-mentioned threading process, the support roll 11 that comes into contact with the back surface of the steel sheet S is a large-diameter roll, so the contact ratio with the steel sheet S is large, and therefore the rolling stress of the steel sheet by the roll is dispersed over a wide area. On the other hand, since the rolling down roll 12 that comes into contact with the front surface is a small diameter roll, the rolling force on the steel plate is locally concentrated. In this way, the present invention applies a sufficient rolling force to plastically deform the plating metal on the upper surface of the convex portion 2 by concentrating the rolling force on the front surface, while dispersing the rolling stress on the back surface. This avoids plastic deformation of the steel plate and prevents the difference in height of the unevenness of the steel plate from decreasing. For this reason, the reduction roll 1
It is advantageous to increase the difference between the diameters of the rolling roll 12 and the supporting roll 11. For example, by making the diameter of the rolling roll 12 approximately 80 mm or less and the diameter of the supporting roll 11 approximately three times or more the diameter of the rolling roll, zinc and When rolling a steel plate coated with a plated metal such as aluminum, only the convex plated metal is smoothed without causing plastic deformation of the steel plate. If it is attempted to achieve the required smoothing in one pass in the rolling process using the rolls 11 and 12, a relatively large rolling force will be required, which may cause plastic deformation of the steel plate. For this reason, as shown in FIG. 3, a multi-stage rolling device in which multiple pairs, preferably 2 to 4 pairs of rolls 11 and 12 are arranged in parallel is used, and the rolls 11 and 12 of each stage are sequentially threaded to achieve a relatively low rolling pressure. It is preferable to gradually achieve smoothing by applying rolling reduction repeatedly with a rolling force. In addition, as the support roll 11, in FIG.
111, if a metal shaft 112 lined with neoprene or urethane rubber 113 is used, the contact ratio with the steel plate increases and the rolling stress of the steel plate can be dispersed over a wider area. , is effective in preventing plastic deformation of steel plates. In a multi-stage rolling down device, it is most effective to replace all of the support rolls in each stage with the above-mentioned rubber-lined rolls, but some of them, for example, the first
Even if it is used only as a support roll for a stage, a considerable effect is exerted. FIG. 4 is a schematic side view showing another specific example of the rolling down device. The device consists of one support roll 21 with a large diameter, a plurality of small-diameter reduction rolls 22 arranged along the outer periphery of the support roll 21, and a back-up roll that comes into contact with each reduction roll to stabilize the rolling force. Consists of roll 23 (in addition, back-up roll 2
Although 3 is not essential, it is effective for stabilizing the rolling force. ) between the rolls 21 and 22, the molten steel plate S is placed, with its back surface facing the support roll 21;
By passing the plate so that the front side is in contact with the reduction roll 22, similar to the apparatus shown in FIG. 2,
The plated metal on the upper surface of the pattern convex portion 2 can be smoothed without causing plastic deformation of the steel plate itself. In this case as well, in order to prevent plastic deformation of the steel plate, it is effective to use a metal shaft 24 with a rubber lining 25 as a support roll as shown in the figure. It is preferable that the diameter of the roll is approximately three times or more that of the reduction roll. By passing the plate through such a roll-down device, it is possible to roll down the roll stably and uniformly even if the degree of flatness is slightly poor. As mentioned above, by repeatedly rolling down the hot-dip galvanized steel plate using the rolling down device, the plated metal on the top surface of the convex portion can be smoothed without causing plastic deformation of the steel plate. The roundness of the corners of the convex parts can be eliminated without any damage to the surface of the convex parts, and since the smoothing described above increases the gloss of the metal plated with the convex parts, the difference in gloss between the concave parts 4 and the convex parts 2 increases, resulting in a reduction in contrast. A strong and clear uneven pattern can be obtained. Note that, before or after smoothing the plated metal using a rolling device, the steel plate can be corrected to the degree of flatness required for a decorative panel by applying it to a roller leveler or a tension leveler. Next, the present invention will be specifically explained with reference to Examples. Example A cold-rolled steel plate with a thickness of 0.8 mm and a width of 914 mm was annealed according to a conventional method, and an uneven pattern with a depression depth of 10% of the plate thickness (an uneven height difference of 0.08 mm) was applied to it by cold rolling. Afterwards, the minimized spangles were hot-dip galvanized, each side weighing 93 to 88 g/ ^m2.
(layer thickness 13.1-12.4μ) of plated metal was deposited.
Then, the plated metal was smoothed by passing it through a rolling down device as shown in FIG. 2. The specifications of the rolling down device are as follows. (a) Number of roll stages: 3 stages (b) Reduction roll: Each stage has a diameter of 50 mm. (c) Support roll: 160mm in diameter for each stage. The first stage support roll is rubber-lined (10 mm thick). 10 samples each were taken before and after the smoothing process using the rolling down device described above, and the roundness of the plated metal at the corners of the convexity, the thickness of the plated metal on the top surface of the convexity, the uneven height difference of the steel plate, and the plated metal were removed. The hardness of the exposed steel plate convex portion was measured. The measurement results are shown in Table 1. Example 2 A cold-rolled steel plate with a thickness of 0.6 mm and a width of 914 mm was annealed according to a conventional method, and an uneven pattern with a depression depth of 8% of the plate thickness (an uneven height difference of 0.048 mm) was added to it by cold rolling. After that, molten aluminum plating is applied to each side to give a thickness of 61 to 55 g/m ² (layer thickness 22.6 to
20.0μ) plated metal was attached. The specifications of the rolling down device are as follows. (a) Support roll: diameter 1200mm. Rubber lining with a thickness of 10 mm is attached to the outer periphery. (b) Roll-down roll: 3 stages. Each roll has a diameter of 45
mm. A back-up roll is installed on each roll to stabilize the rolling force. Ten samples each were taken before and after the smoothing treatment using the reduction device, and the same measurements as in Example 1 were performed. The results are shown in Table 1. Comparative Example A hot-dip galvanized steel sheet with an uneven pattern obtained in the same process as in Example 1 was subjected to rolling with a skin pass mill to smoothen the plated metal. however,
The diameter of the opposing upper and lower rolls of the skin pass mill was 230 mm, and the rolls were used to apply a reduction with an elongation rate of 1.2%. The measurement results obtained for each of the 10 samples taken before and after the skin pass are also shown in Table 1.

[Table] As shown in Table 1 above, the roundness of the plated metal at the corners of the convex portions is almost completely eliminated by the smoothing treatment according to the present invention, and the height of the unevenness before and after the treatment is reduced. Almost no change was observed in the difference. Furthermore, the fact that the hardness of the convex parts of the steel plate remains almost unchanged before and after treatment indicates that no plastic deformation occurs in the steel plate;
This corresponds to the fact that the unevenness height difference before treatment is maintained. Further, although the thickness of the plated metal on the upper surface of the convex portion is slightly reduced by the smoothing treatment, it is still sufficient to cause no problems in terms of corrosion resistance. On the other hand, in the comparison method using skin paths,
Although the roundness of the convex corners has been eliminated, the fifth
As shown in the figure, sagging 5 of the zinc coating occurs at the corners of the convex portions 2, and as can be seen from the increase in hardness of the convex portions, plastic deformation has occurred in the steel plate, and therefore the height difference between the concave and convex portions also increases. It has decreased significantly compared to before treatment. As described above, according to the present invention, it is possible to sharpen the outline of the convex portion without impairing the height difference between the concave and convex portions, and to strengthen the difference in gloss between the concave portion and the convex portion. Even if the difference is relatively small, it is possible to produce a hot-dipped galvanized steel plate with an uneven pattern with excellent contrast, and this can be used for various panels such as interior panels, door panels, front panels of stoves, shutter slats, etc. can enhance the decorative effect.

[Brief explanation of the drawing]

1 and 2 are cross-sectional explanatory diagrams showing the uneven surface condition of a hot-dipped galvanized steel plate with an uneven pattern, FIG. 3 is a schematic side view showing a specific example of the rolling down device used in the present invention, and FIG. A side schematic diagram showing other specific examples,
FIG. 5 is an explanatory cross-sectional view showing a deformed state of the metal plated on the convex portion. 1: Plated metal, 2: Convex portion, 4: Concave portion, 11,
111, 21: Support roll, 12, 22: Reduction roll, 23: Back up roll, 112, 2
4: Metal shaft, 113, 25: Rubber lining.

Claims (1)

[Claims] 1. After applying molten metal plating to a cold-rolled steel plate with an uneven pattern, or after performing an alloying treatment following that, the surface without the uneven pattern of the steel plate is coated with rubber on a metal or metal shaft. The plated layer on the upper surface of the convex portion is smoothed by supporting it with a lined support roll and rolling down the uneven patterned surface with a metal reduction roll having a smaller diameter than the support roll. A method for manufacturing a molten metal plated steel plate with an uneven pattern.