JP7360041B2 - Plated steel plate having embossed portions and method for forming embossed portions on plated steel sheets - Google Patents

Description

The present invention relates to a plated steel sheet having an embossed portion and a method for forming an embossed portion on a plated steel sheet.

BACKGROUND ART Embossed steel plates have been known for the purpose of enhancing design and functionality. The type of steel plate to be embossed is generally, for example, ordinary steel or stainless steel.

For example, Patent Document 1 discloses a device in which the surface is embossed so that the work of removing the paper affixed from the surface can be easily performed.

Further, Patent Document 2 discloses a steel plate whose surface is embossed in order to realize a steel plate with excellent slip resistance.

Japanese Patent Application Publication No. 2002-66657 Japanese Patent Application Publication No. 2000-129411

By the way, when a steel plate is used outdoors, for example, excellent corrosion resistance is required. Therefore, as a steel plate used outdoors, for example, a zinc-based plated steel plate, in which the surface of ordinary steel is plated with a zinc-based metal, is used. be done.

However, when embossing is performed on a plated steel sheet, cracks may occur in the plating layer or, if the plating layer is coated with a film, or the plating layer or the above-mentioned film may peel off from the base steel sheet. Probability is high. Therefore, examples of embossing applied to plated steel sheets are rarely seen.

The present invention has been made in view of these points, and an object of the present invention is to provide a plated steel sheet having a concave embossed portion and a method for forming a concave embossed portion on a plated steel sheet.

(1) The plated steel sheet having an embossed portion according to the present invention has an emboss depth of 60 μm or less from the surface of the concave plated steel sheet to the bottom of the embossed portion , and the embossed portion is formed from the surface of the plated steel sheet. A concave curved portion having a radius of curvature of 0.15 mm or more is formed up to the bottom of the embossed portion .

According to the plated steel sheet in (1) above, if the plating layer or the coating layer is coated with a coating, cracks may occur in the coating, or the coating layer or the above coating may peel off from the base steel sheet. It becomes possible to suppress this, and it becomes possible to provide a plated steel sheet having a concave embossed part.

( 2 ) The method for forming a concave embossed portion on a plated steel sheet of the present invention is such that the embossing depth from the surface of the plated steel sheet to the bottom of the embossed portion is 60 μm or less , and The plated steel sheet is rolled so that a concave curved portion having a radius of curvature of 0.15 mm or more is formed up to the bottom of the embossed portion.

According to the above method ( 2 ) of forming concave embossed portions on a plated steel sheet, if the plating layer or the plating layer is coated with a coating, cracks may occur in the coating, or the plating layer may be removed from the base steel plate. It becomes possible to suppress the above-mentioned coating from peeling off.

According to the present invention, it is possible to provide a plated steel sheet having a concave embossed portion and a method for forming a concave embossed portion on a plated steel sheet.

(A) An example of a schematic diagram showing an enlarged part of the cross section of the base steel sheet before being embossed. (B) A schematic diagram showing an enlarged part of the cross section of the plated steel sheet after being embossed. This is an example. This is an example of a list showing test conditions for forming an embossed portion on a plated steel sheet. It is a graph showing an example of the results of verifying the presence or absence of white rust by conducting a salt spray test using an embossed test piece. It is an image showing an example of a state in which white rust has occurred near the concave curved portion of the embossed portion after the salt spray test. This is an example of a graph showing the relationship between the uneven level difference D of the embossed test piece and the white rust occurrence rate, and was created based on FIG. 3. This is an example of a graph showing the relationship between the radius of curvature of the concave curved portion of the embossed portion of the embossed test piece and the incidence of white rust, and was created based on FIG. 3.

As one embodiment of the present invention, a plated steel sheet having an embossed portion and a method for forming the embossed portion on the plated steel sheet will be described below.

Note that embossing is generally performed by, for example, rolling, pressing, rolling, shot blasting, etching, etc., but in this embodiment, embossing is performed on a plated steel plate by rolling using an embossing roll. An example of the case will be explained.

FIG. 1(A) is an example of a schematic diagram showing an enlarged part of the cross section of the base steel plate 2 before being embossed. The plated steel sheet 1 in this embodiment includes a base steel sheet 2, a plating layer 3 coated on the surface of the base steel sheet 2, and a coating 4 coated on the surface of the plating layer 3. Note that the coating 4 may be, for example, an organic resin coating or an inorganic resin coating. Moreover, although the case where the plated steel sheet 1 in this embodiment is coated with the coating 4 has been described as an example, the plated steel plate 1 that is not coated with the coating 4 may also be used.

In this embodiment, the plated steel plate 1 to be embossed is, for example, a black plated steel plate that is a zinc-based plated steel plate. The black plated steel sheet includes a base steel sheet 2 and a surface of the base steel sheet 2 containing Al: 0.1 to 22.0% by mass, Mg: 0.1 to 10.0% by mass, and black oxidation of Zn. A Zn plating layer 3 containing molten Al and Mg is distributed in the plating layer.

Next, the plated steel sheet 1 on which the embossed portions 6 are formed by embossing will be described together with the embossing roll 30 for forming the embossed portions 6.

FIG. 1(B) is an example of a schematic diagram showing an enlarged part of the cross section of the plated steel sheet 1 after being embossed. In addition, in FIG. 1(B), for convenience of explanation, a part of the cross section of the embossing roll 30 is also shown in an enlarged manner. On the surface of the plated steel sheet 1 after being embossed, a concave embossed part 6 and a flat part 7 are formed on the surface other than the embossed part 6. The flat portion 7 is a non-embossed portion of the surface of the plated steel sheet 1 other than the embossed portion 6 . Note that the embossed portion 6 is formed by pressing a roll convex portion 31, which will be described later, against the surface of the plated steel sheet 1.

The embossed portion 6 is formed in an emboss formation process in which the plated steel sheet 1 is rolled. In the embossing forming step, the plated steel sheet 1 having the concave embossed portions 6 is formed by rolling with the embossing roll 30 .

The embossed portion 6 includes an embossed bottom portion 21 formed as a bottom portion of the embossed portion 6 formed in a concave shape, and an embossed portion formed as a side portion of the embossed portion 6 extending from the embossed bottom portion 21 to the flat portion 7 of the plated steel plate 1. It has a side portion 22 and a concave curved portion 23 that smoothly connects the embossed bottom portion 21 and the embossed side portion 22 with a predetermined radius of curvature.

In this specification, the distance from the flat part 7 of the plated steel sheet 1 to the embossed bottom part 21 (ie, the embossed depth) shown in FIG. 1(B) is referred to as an uneven step D. Strictly speaking, in one embossed part 6, the distance from the flat part 7 to the embossed bottom part 21 is not necessarily constant, so here, the average distance from the flat part 7 to the embossed bottom part 21 is defined as the uneven step D. .

The embossing roll 30 has a plurality of roll convex portions 31 that protrude from the outer peripheral surface of the embossing roll 30, as shown in FIG. 1(B). The roll convex portion 31 has a top portion 32 formed in a flat surface shape at the tip portion, and a convex curved portion 33 formed as a curved surface having a predetermined radius of curvature at the edge portion of the top portion 32. The convex curved portion 33 is a portion for forming the concave curved portion 23 of the embossed portion 6 on the plated steel plate 1.

Next, a description will be given of an evaluation regarding corrosion resistance conducted for the purpose of clarifying the conditions for embossing the plated steel sheet 1 to suppress the occurrence of white rust. For evaluation of corrosion resistance, a salt spray test (SST test) based on JIS Z2371 was conducted using the plated steel sheet 1 embossed with an embossing roll 30. In the salt spray test, a 5% NaCl aqueous solution at 35° C. is sprayed onto the surface of the plated steel plate 1 having the embossed portions 6, and it is visually confirmed whether white rust has occurred after 24 hours and 48 hours. I went there. In the salt spray test, if the appearance of white rust on the plated steel sheet 1 was confirmed, it was determined that white rust had occurred. Furthermore, if no white rust was observed on the surface of the plated steel sheet 1, it was determined that no white rust was generated. Furthermore, even if no white rust was observed 24 hours after spraying the NaCl aqueous solution, it was determined that white rust had occurred if white rust was observed 48 hours later.

FIG. 2 is an example of a list showing test conditions for forming embossed portions 6 on plated steel sheet 1. In the salt spray test, a black plated steel plate with a thickness of 0.8 mm, a width of 60 mm, and a length of 1000 mm was used. Furthermore, the embossing roll 30 for forming the embossed portions 6 on the plated steel sheet 1 had a diameter of 110 mm.

Regarding the line load (also referred to as roll line load) of the embossing roll 30 in this embodiment, a load of 0.6 kN/mm to 1.6 kN/mm was applied to the plated steel sheet 1. At this time, it is possible to increase the uneven step D formed in the embossed portion 6 by, for example, rolling with an increased roll line load. Moreover, it is also possible to reduce the uneven step D formed in the embossed portion 6 by rolling with a reduced roll line load.

The embossed portions 6 were formed on the plated steel sheet 1 using the embossing roll 30 at a rolling speed of 1 m/min. In addition, when increasing or decreasing the uneven step D, it is possible to do so by changing the magnitude of the roll line load as described above, but it is also possible to change the rolling speed or reduce the embossed portion 6. This can also be done by changing the hardness of the steel plate that forms it.

When rolling the plated steel sheet 1 with the embossing roll 30, rolling oil was not used. Moreover, the rolling of the plated steel sheet 1 using the embossing roll 30 was performed with one pass.

FIG. 3 is a graph showing an example of the results of a salt spray test conducted using an embossed test piece to determine whether or not white rust occurs. In addition, in FIG. 3, the uneven step D formed on the test piece is shown on the horizontal axis, and the curvature radius of the concave curved part 23 formed on the test piece is shown on the vertical axis. The test pieces used in the salt spray test were embossed using four types of embossing rolls 30 in which the radius of curvature of the convex curved portion 33 was 0.02 mm, 0.08 mm, 0.18 mm, and 0.40 mm. Note that the thickness of the steel plate used for the test piece was 0.8 mm.

In this embodiment, 22 specimens were embossed using an embossing roll 30 whose convex curved portion 33 had a radius of curvature of 0.02 mm, and an embossing roll 30 whose convex curved portion 33 had a radius of curvature of 0.08 mm was fabricated. 27 test pieces were prepared using an embossing roll 30 in which the radius of curvature of the convex curved portion 33 was 0.18 mm. Twenty-seven test specimens were embossed using a 0.40 mm embossing roll 30. Then, a salt spray test was conducted using these test pieces.

Note that the uneven step D of the test piece embossed using the embossing roll 30 in which the radius of curvature of the convex curved portion 33 is 0.02 mm is within the range of 0.04 mm to 0.15 mm, and the radius of curvature of the convex curved portion 33 is 0. The uneven step D of the test piece embossed using a .08 mm embossing roll 30 was within the range of 0.04 mm to 0.16 mm, and the curvature radius of the convex curved portion 33 was embossed using an embossing roll 30 of 0.18 mm. The uneven step D of the test piece was 0.03 mm to 0.06 mm, and the uneven step D of the test piece embossed using an embossing roll 30 with a convex curved portion 33 having a radius of curvature of 0.40 mm was 0.02 mm. It was within the range of ~0.06 mm. However, the above-mentioned value of unevenness step D was rounded to the third decimal place.

Further, the radius of curvature of the concave curved portion 23 of the test piece embossed using the embossing roll 30 in which the radius of curvature of the convex curved portion 33 is 0.02 mm is within the range of 0.04 mm to 0.07 mm; The radius of curvature of the concave curved portion 23 of the test piece embossed using the embossing roll 30 with a radius of curvature of 0.08 mm is within the range of 0.06 mm to 0.13 mm, and the radius of curvature of the convex curved portion 33 is 0.18 mm. The radius of curvature of the concave curved portion 23 of the specimen embossed using the embossing roll 30 was within the range of 0.24 mm to 0.54 mm, and the radius of curvature of the convex curved portion 33 was embossed using the embossing roll 30. The radius of curvature of the concave curved portion 23 of the processed test piece was within the range of 0.47 mm to 2.09 mm. However, the value of the radius of curvature of the concave curved portion 23 is rounded to the third decimal place.

In FIG. 3, the hatched area indicates the area where test pieces in which white rust did not occur in the salt spray test are distributed. That is, when embossing is performed using the embossing roll 30 in which the radius of curvature of the convex curved portion 33 is 0.18 mm, and when embossing is performed using the embossing roll 30 in which the radius of curvature of the convex curved portion 33 is 0.40 mm, It was possible to suppress the occurrence of white rust caused by the salt spray test. On the other hand, in the test pieces outside the hatched area in FIG. 3, white rust occurred in the salt spray test. Although it is not shown in Fig. 3, those skilled in the art know that white rust occurs in a salt spray test in a range where the uneven step D is larger than 0.08 mm and the radius of curvature of the concave curved portion is larger than 0.2 mm. It is self-evident between.

FIG. 4 is an image showing an example of a state in which white rust 8 has occurred near the concave curved portion 23 of the embossed portion 6 after the salt spray test. FIG. 4 shows an enlarged photograph of the surface of the plated steel sheet 1 after the salt spray test. In FIG. 4, it can be seen that this occurs mainly near the edge portion of the embossed portion 6, more specifically, on the embossed side portion 22 and the concave curved portion 23. The occurrence of white rust 8 in the vicinity of these embossed portions 6 is thought to be due to cracks occurring in the coating 4 of the plated steel sheet 1 as the coating 4 is stretched or bent by embossing. Note that when cracks occur in the plating layer 3, it is considered that the coating 4 is also damaged.

By the way, referring to FIG. 3, it is presumed that the uneven step D (see FIG. 1(B) for both) of the embossed portion 6 formed on the plated steel sheet 1 influences the generation of white rust 8. Furthermore, it is presumed that the radius of curvature of the concave curved portion 23 of the embossed portion 6 formed on the plated steel sheet also influences the occurrence of white rust 8. In the following, we will first consider the relationship between the uneven step D and the rate of white rust occurrence, and then consider the relationship between the radius of curvature of the concave curved part 23 of the embossed part 6 formed on the plated steel sheet 1 and the rate of white rust occurrence. Let's consider.

FIG. 5 is an example of a graph showing the relationship between the uneven level difference D of the embossed test piece and the incidence of white rust, and was created based on FIG. 3. In addition, in FIG. 5, the value of the unevenness step D shown on the horizontal axis is shown as a value rounded to the third decimal place. In addition, the ratio shown on the vertical axis in Fig. 5 is the number of test pieces in which white rust 8 did not occur at each value of unevenness step D compared to the number of test pieces in which the presence or absence of white rust 8 was evaluated. This is the value divided by the number of pieces.

As shown in FIG. 5, as a result of conducting a salt spray test using the above-mentioned test piece, if the uneven step D formed on the test piece exceeds 0.06 mm (more specifically, 0.063 mm), , white rust 8 occurred in all test pieces. On the other hand, it was confirmed that the proportion of test pieces in which white rust 8 did not occur increased rapidly when the unevenness step D reached 0.06 mm. This is achieved by reducing the uneven step D of the embossed portion 6 formed on the plated steel sheet 1, so that the plating layer 3 of the plated steel sheet 1 or, if the plating layer 3 is coated with a coating 4, the coating 4 can be removed. This is thought to be because rolling with the embossing roll 30 prevented excessive elongation and suppressed the occurrence of cracks.

In addition, to explain in detail the results of the salt water spray test shown in FIG. 5, the salt water spray test was conducted when the unevenness level difference D was in the range of 0.04 mm to 0.06 mm (more specifically, 0.063 mm). White rust 8 did not occur in 29 of the 45 test pieces. In addition, in FIG. 5, the results of the salt spray test conducted using the test pieces with the unevenness step D value of 0.04 mm to 0.06 mm are shown as the results when the unevenness step D value is 0.05 mm. did.

Moreover, when the value of the unevenness step D was less than 0.04 mm, white rust 8 did not occur in 24 of the 29 test pieces subjected to the salt spray test. That is, when the uneven step D was 0.04 mm or less, the ratio of the number of test pieces in which white rust 8 did not occur was 0.83. In addition, in FIG. 5, the ratio of the number of test pieces in which white rust 8 did not occur when the value of the uneven level difference D is 0.04 mm or less is expressed as the result when the uneven level difference D value is 0.03 mm.

FIG. 6 is an example of a graph showing the relationship between the radius of curvature of the concave curved portion 23 of the embossed portion 6 of the embossed test piece and the incidence of white rust, and was created based on FIG. be. For convenience of explanation, the value of the radius of curvature of the concave curved portion 23 is rounded to the fourth decimal place for values less than 0.2 mm, and rounded to the second decimal place for values of 0.2 mm or more. value. In addition, the ratio shown on the vertical axis in FIG. 6 is the number of test pieces in which white rust 8 did not occur at each value of the radius of curvature of the concave curved portion 23, and the number of test pieces in which white rust 8 did not occur was evaluated for the presence or absence of white rust 8. This is the value divided by the number of test pieces.

As shown in FIG. 6, as a result of conducting a salt spray test using the above-mentioned test piece, when the radius of curvature of the concave curved portion 23 formed on the test piece was 0.132 mm or less, white rust 8. It was confirmed that this occurs. On the other hand, it was confirmed that the percentage of test pieces in which white rust 8 did not occur increased rapidly when the radius of curvature of the concave curved portion 23 reached 0.132 mm. This is caused by the difference in ductility between the base steel plate 2 and the plating layer 3 or coating 4 due to the locally bent concave portion 23 in the embossed part 6. This is also considered to be because peeling from the coating 4 could be suppressed.

In addition, to explain in detail the results of the salt spray test shown in FIG. 6, white rust 8 did not occur in any of the test pieces in which the radius of curvature of the concave curved portion 23 was 0.2 mm or more. On the other hand, when the radius of curvature of the concave curved portion 23 was within the range of 0.034 mm to 0.132 mm, white rust 8 occurred in all 68 test pieces subjected to the salt spray test.

According to the embodiments described above, the following inventions can be provided.

The plated steel sheet 1 having the embossed portion 6 according to the present invention has an emboss depth of 60 μm or less from the surface thereof to the bottom of the embossed portion 6. In this case, it is considered that the plated layer 3 and coating 4 of the rolled plated steel sheet 1 will not be in an excessively stretched state, and cracks will occur in the plated layer 3 and coating 4, and the plated layer 3 will be removed from the base steel plate 2. It becomes possible to suppress the peeling of the coating 4 and the like. As a result, it is possible to provide a plated steel sheet 1 having embossed portions even when excellent corrosion resistance is required, such as when used outdoors, for example.

The plated steel plate 1 having the embossed portion 6 according to the present invention has a concave curved portion 23 having a radius of curvature of 0.15 mm or more between the surface thereof and the bottom of the embossed portion 6. In this case, it becomes possible to further suppress the generation of cracks in the plating layer 3 and the coating 4 and the peeling of the plating layer 3 and the coating 4 from the base steel plate 2. In particular, it is considered to be effective in suppressing peeling between the base steel plate 2 and the plating layer 3 or/and coating 4, which is caused by the difference in ductility between the base steel plate 2 and the plating layer 3 or coating 4.

In the method of forming an embossed portion on a plated steel sheet according to the present invention, the plated steel sheet 1 is rolled so that the embossing depth from the surface of the plated steel sheet 1 to the bottom of the embossed portion 6 is 60 μm or less. In this case, when the plated steel sheet 1 is rolled, the plating layer 3 and the coating 4 will not be in an excessively elongated state, and cracks will occur in the coating layer 3 and the coating 4, and the plating layer will be removed from the base steel plate 2. 3 and the coating 4 can be prevented from peeling off. As a result, it is possible to provide a method for forming embossed portions on a plated steel sheet that can be used in situations where excellent corrosion resistance is required, such as outdoors.

In the method of forming an embossed portion on a plated steel sheet according to the present invention, a concave curved portion 23 having a radius of curvature of 0.15 mm or more is formed from the surface of the plated steel sheet 1 to the bottom of the embossed portion 6. A plated steel sheet 1 is rolled. In this case, it becomes possible to further suppress the generation of cracks in the plating layer 3 and the coating 4 and the peeling of the plating layer 3 and the coating 4 from the base steel plate 2.

1 Plated steel plate 6 Embossed part 21 Embossed bottom part 23 Concave curved part

Claims (2)

A plated steel plate having a concave embossed part,
The embossing depth from the surface of the plated steel sheet to the bottom of the embossing portion is 60 μm or less,
The embossed portion has a concave curved portion having a radius of curvature of 0.15 mm or more between the surface of the plated steel plate and the bottom of the embossed portion.
A plated steel sheet characterized by: A method of forming a concave embossed part on a plated steel plate, the method comprising:
The emboss depth from the surface of the plated steel sheet to the bottom of the embossed portion is 60 μm or less, and the radius of curvature is 0.15 mm or more from the surface of the plated steel sheet to the bottom of the embossed portion. A method for forming an embossed portion on a plated steel sheet, the method comprising rolling the plated steel sheet so that a concave curved portion is formed.