JP3269373B2 - Metal roll surface processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for surface-treating a metal roll used for producing a matte-finished steel sheet used for building materials and the like.

[0002]

2. Description of the Related Art In recent years, stainless steel sheets have been used as exterior materials for building materials, railway vehicles, and the like, and surface finish steel sheets other than the conventional bright finish steel sheets have been required.

[0003] A common method of delustering the surface of a steel sheet is as follows:
There is a so-called dull finishing method in which a steel sheet is rolled with a dull roll for cold rolling whose surface is uniformly roughened, and the roll surface is transferred to the steel sheet.

[0004] Conventional surface treatment of dull finishing rolling rolls involves a method of projecting a high-speed steel ball having a sharp ridge angle on the roll surface, a so-called grid, or a matte-like pattern on the roll surface by electric discharge machining. A molding method and the like have been adopted.

Japanese Patent Application Laid-Open No. 1-118301 discloses a method of manufacturing a dull-finished austenitic stainless steel sheet in which a normal dull finish is performed and then the surface of the steel plate is etched with a pickling liquid.

As a method for processing the surface of a roll, Japanese Patent Application Laid-Open No. 4-46612 discloses a method of forming microscopic roughness on the roll surface using hard alumina as shot particles. No. 175882 discloses a roll surface processing method by laser processing and etching.

[0007]

In order to frost the surface of the steel sheet, it is necessary to provide irregularities on the surface of the steel sheet to irregularly reflect the incident light in order to suppress the regular reflection of light.

FIG. 1 is a diagram for explaining the relationship between incident light and reflected light. FIG. 7A is a schematic diagram showing the relationship between incident light and reflected light distribution. If the steel plate surface is flat and the surface irregularities are small, the incident angle and the reflection angle become the same. As shown in (b), when light is incident on a surface of a steel sheet having irregularities from a certain direction, the reflection angles are varied and irregularly reflected. However, the distribution of the reflected light is determined by the degree of distribution of the surface irregularities, and this distribution state is It affects the matte feeling given to human eyes. FIG.
(C) and (d) show how the reflected light distribution changes depending on the size of the ridge angle of the irregularities on the steel sheet surface. The ridge angle is θ in the figure.
Is the angle of the tip of the convex body as shown by. As shown in (d), in order to reflect the incident light in all directions and give a matte feeling, the smaller the ridge angle of the unevenness on the steel sheet surface, the better.

However, it is difficult to reduce the ridge angle by the conventional method of projecting a grid, which is a dull machining method, or the method of electric discharge machining, and as shown in FIG. Larger than the vector,
Matting degree decreases.

In the method of projecting a grid, a steel slab or a steel ball, which is generally called a grid or a shot, is caused to collide with the roll surface, and irregularities are imparted to the roll surface by the collision energy. At this time, the grid repels on the roll surface and does not sink into the roll. Therefore, the formed depression becomes a crater whose depth is smaller than its outer diameter. In this method, the ridge angle cannot be reduced basically only by repeating this step a plurality of times.

FIGS. 2A and 2B are views showing actual dulled surface profiles. FIG. 2A shows the surface profile of a grid-projected roll, and FIG. 2B shows the surface profile after one electric discharge machining. These are displayed at the actual magnification in the vertical and horizontal directions, and can be formed only in the unevenness having a large ridge angle as shown in FIG.

If the projection speed of the grid is increased to reduce the ridge angle and biting into the roll surface is allowed, there is no way to remove this, and the projection speed of the grid cannot be increased. Similarly, in the case of electric discharge machining, the crater by one electric discharge becomes a crater having a smaller depth than the outer diameter as shown in FIG. This is because the metal melted by the discharge flows before it solidifies,
It is inevitable that only a crater of such a shape can be obtained.

The method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1-118301 does not improve the dulling method. Further, the method is a method in which the steel sheet is etched by pickling after dull rolling. A line is required, equipment and manufacturing costs are increased, and there is a problem associated with waste acid solution treatment, which is problematic in terms of pollution.

In the method disclosed in Japanese Patent Application Laid-Open No. 4-46612, only alumina is used as the projecting material, and the above-mentioned problem of the projection dull cannot be basically avoided.

Further, the method disclosed in Japanese Patent Application Laid-Open No. Hei 2-175882 makes it possible to form steep irregularities.
However, due to the characteristics of the processing method in which the roll is rotated and moved in the axial direction to form craters one by one, the roll surface and the rolled steel plate surface have a regular uneven pattern and are not suitable as an exterior material. The reason for this is that the exterior material is usually used for an exterior with a large area, and several steel plates are spliced together, so if irregularities are regular, the seam will be emphasized.

The present invention has been made in view of the above problems, and has as its object to provide a method of processing a roll surface capable of imparting excellent mattability to a steel sheet surface.

[0017]

Means for Solving the Problems The present inventors have conducted various experiments and studies on a method for processing a roll surface capable of imparting excellent matting properties to the surface of a steel sheet, and have obtained the following findings.

1) It is difficult to form unevenness having a sharp ridge angle by conventional surface processing methods using grid projection or electric discharge machining due to the characteristics of these processing methods.

2) The surface processing method using high-density energy such as laser can process steep irregularities. However, the minimum size of one crater is about 150 μm in diameter. Is difficult to process.

3) The surface of the dull roll for matting of the exterior steel plate is preferably processed into a concavo-convex state having a sharp ridge angle, a fine pitch, and a random pattern.

4) The processing of the surface state as described in 3) above
This is achieved by spraying an acid-resistant resin liquid with a two-fluid nozzle to form droplets having an average particle diameter of 20 μm or less, applying the coating on the roll surface in a patchy manner, and etching or plating the resin-free metal surface. be able to.

The gist of the present invention is based on such knowledge. The gist of the invention is that "a two-fluid nozzle sprays an acid-resistant resin liquid and a gas to form droplets having an average particle diameter of 20 μm or less. Spray the mist-like acid-resistant resin liquid onto the surface of the metal roll to apply it in a patch, and then etch the roll surface to which the acid-resistant resin does not adhere, or apply the metal to the roll surface to which the acid-resistant resin does not adhere. A metal roll surface processing method characterized by plating, and a metal roll surface processing method characterized by plating the roll surface with a metal after removing the acid-resistant resin from the surface of the roll processed by these methods. "It is in.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Roll etching is a process that chemically erodes the surface of a roll. If an acid-resistant resin is applied in fine patches on the roll surface, the portion where the resin is not applied can be reduced. Selective etching results in steep irregularities.

However, in order to perform such processing, it is necessary to apply an acid-resistant resin to the roll surface almost uniformly and at an extremely fine pitch.

FIG. 3 is a diagram for explaining a wet etching method used in a general lithography method. The etching includes the steps A to D in FIG. First, a light-curable acid-resistant resin 2 is uniformly applied on a metal 1 to be processed (Step A), covered with a mask 3 having a predetermined pattern, and then a light source corresponding to the spectral sensitivity of the acid-resistant resin such as ultraviolet rays. (Step B). As a result, the portion 4 not covered with the mask is hardened (B), and the mask pattern is transferred by developing (Step C). An etching solution is sprayed on the surface to etch only the portion not covered with the resin (step D) to obtain a metal product having a predetermined pattern. At this time, since the etching becomes isotropic as a feature of the wet etching, a wraparound called side etching occurs, and the lower side 5 of the covering portion is also eroded, which leads to a reduction in resolution.

There are the following problems in applying the above technology to roll processing. First, since the object to be processed is cylindrical,
It is difficult to make a mask. If a flat mask is formed, a seam of the mask is formed on the roll, which is not suitable for a roll that is continuously rolled. Further, there is a point that fine unevenness cannot be obtained with the current etching technology.

In order to increase the resolution, it is necessary to improve the mask manufacturing technology, the straightness of the light source during exposure, and the like.
This leads to an increase in roll processing costs. Even if the above problem can be avoided, there is also a problem that since a mask is used, a certain pattern, that is, regularity can be obtained, so that it is not suitable as an exterior material.

Therefore, in the present invention, a two-fluid nozzle is used as a means for applying the acid-resistant resin finely and intermittently on the roll surface without using the mask.

FIG. 4 is a diagram showing an example of a two-fluid nozzle used in the method of the present invention. As shown in the drawing, this nozzle has an inner nozzle 6 for injecting an acid-resistant resin liquid 8 and an outer nozzle 7 having a small-diameter injection port for injecting gas to the outside.
The nozzle has a double structure. Liquid and gas are supplied by pumps whose flow rate and pressure can be adjusted respectively. When a liquid and a gas are simultaneously ejected by a nozzle having such a double structure, the liquid is formed into fine spherical droplets corresponding to the atmospheric pressure and the liquid pressure, and is ejected into the atmosphere as a mist. At this time, the size of the liquid droplet can be freely controlled by adjusting the liquid pressure, the atmospheric pressure, and the diameter of the injection port, and can be adjusted to a submicron size by extremely reducing the liquid flow rate. The droplets sprayed in the form of a mist adhere to the metal surface in a dotted manner with a fixed adhesion efficiency and spread over a predetermined area. When an acid-resistant resin is used as a liquid and air is used as a gas in the two-fluid nozzle and sprayed onto a metal roll, fine droplets of 20 μm or less can be formed by adjusting the liquid pressure and pressure. The particle size of the attached droplets and the distance between the particles are random. Further, the average particle diameter of the attached droplets and the average interval between the droplets can be controlled by adjusting the roll rotation speed at the time of ejection and the ejection distance. Since the acid-resistant resin liquid has a higher viscosity than water or the like, even if it adheres to the roll surface, it retains its form to some extent and becomes a hemispherical droplet.

As the acid-resistant resin, acrylic polymers, acrylic monomers, oligomers and the like can be used.

The reason why the acid-resistant resin liquid is sprayed as droplets having an average particle diameter of 20 μm or less is as follows.

If the average particle size exceeds 20 μm, after adhering to the roll surface, it spreads widely and hinders intermittent adhesion of the resin, making it impossible to apply the resin in a patchy manner. On the other hand, if the particle diameter is large, the side etching takes a long time, and the side etching is insufficient with a normal etching time, so that a smooth portion remains on the roll surface. This part is transferred to the steel sheet as a smooth part during rolling, and as a result, the mirror reflection of the steel sheet becomes large and the matting property is inferior.

Therefore, the average particle size of the droplets needs to be 20 μm or less, preferably 5 to 15 μm.

The average particle size of the acid-resistant resin droplets is determined by injecting the acid-resistant resin liquid into the air and flying at a very high speed (approximately 1 / 250,000 second). And measuring the particle size on the photograph, or using an image processing device or the like to automatically measure and obtain a particle size distribution. When the pressure and flow rate of the air and the pressure and flow rate of the acid-resistant resin solution are constant, the average particle diameter of the particles that can be generated is constant, so it is necessary to obtain the injection conditions and the average particle diameter for each nozzle in advance. Good.

After the acid resistant resin is applied on the roll surface, the roll surface on which the resin does not adhere is etched by an etching solution. The etchant may be any acid capable of etching the roll surface, and is preferably a ferric chloride solution, a cupric chloride solution, or the like.

It should be noted that the etching of the roll surface to which the resin does not adhere includes, of course, side etching that occurs as the etching proceeds from the roll surface.

FIG. 5 is a schematic view of the etched state.
FIG. 1A is a cross-sectional view showing a state in which an acid-resistant resin liquid is sprayed from a nozzle and applied to a roll surface, FIG. 1B is a view showing an initial state of etching with an etchant, and FIG. It is a figure showing a state at the time.

When the acid-resistant resin liquid is sprayed toward the roll surface and the acid-resistant resin liquid is applied in a patchy manner, the result is as shown in FIG. The part 2 is not etched,
The part 4 without resin is etched. The initial state of the etching is as shown in (b), and the etching proceeds isotropically, so that the lower part of the resin film is also etched by side etching, resulting in sharp irregularities as shown in (c).

As described above, the present invention effectively utilizes the side etching which is not preferable in the lithography method.

After etching to a predetermined roughness, the acid-resistant resin is removed with a solvent such as toluene to obtain a dull roll. In addition, the etching, after applying the resin,
The entire roll may be immersed in an etching solution.

Next, a method of forming unevenness by plating will be described. Spraying the acid-resistant resin by a two-fluid nozzle and applying it to the roll surface is the same as the above method.
After coating, when the entire surface of the roll is plated, plating grows only in the portion where the acid-resistant resin is not adhered, and plating does not grow because the portion covered with the resin is insulative. When the acid-resistant resin is removed after growing to a predetermined plating thickness, a dull roll having sharp irregularities is obtained.

As the plating, chromium electroplating excellent in wear resistance is preferable, and other examples include nickel (lower layer) -chromium (upper layer) two-layer electroplating.

As conditions for plating, the current density may be about ²⁰ to 40 A / dm ² , and the plating thickness may be about 7 to 15 μm.

FIG. 6 is a sectional view showing the state of irregularities after processing the surface of the roll by the method of the present invention. (A)
Indicates an uneven state processed by etching, and (b) indicates an uneven state due to plating.

In the etching process, as shown in FIG.
Since the space 4 between the resin droplets becomes a concave portion, the resin applied portion 2 becomes a convex shape and an island shape. On the other hand, a steel sheet rolled by such a surface roll is a steel sheet in which concavities are dotted.

On the other hand, in the method by plating, as shown in FIG. 2B, the resin droplets 4 become convex due to the plating metal, and the resin coating portion 2 is not plated, so that the resin droplets 4 are formed as concaves on the roll surface. It becomes the remaining dull form. Therefore, in the steel sheet rolled by the roll having the surface in this state, the convex portions remain in an island shape.

Although there is no significant difference in the matting property between the two as an exterior material, for example, from the viewpoint of the adhesion of dirt, it is more difficult for dirt to adhere if the projections remain on the steel plate in a dotted manner.
In addition, the attached dirt is easy to remove. Therefore, both are used properly depending on the purpose of use of the steel sheet.

In this way, a dull roll, which cannot be obtained by the conventional method, can be manufactured. However, when rolling is performed for a long period of time or when the rolling conditions are severe, abrasion of the convex portion may become a problem. In such a case, it is preferable to apply hard plating after processing into irregularities by the etching process or the plating process. This plating is also preferably the hard chromium plating described above.

Hereinafter, effects of the present invention will be described based on examples.

[0050]

【Example】

(Example 1) A photocurable acrylic polymer to which a sensitizer was added was used as an acid-resistant resin solution, and air was used as a gas. The viscosity of the resin was 40 cps / 25 ° C.

The nozzle of the structure shown in FIG.
mm. The roll has a diameter of 350 mm,
A cast iron roll having a barrel length of 600 mm was used.

While rotating the roll while supporting the roll with a bearing, an acrylic polymer was sprayed from the two-fluid nozzle toward the roll surface under the conditions shown in Table 1. The liquid pressure and the atmospheric pressure were changed, and the average particle diameter of the droplet was changed in the range of 6 to 35 μm.

[0053]

[Table 1]

The injection time in the table was adjusted by the opening and closing time of a shutter provided between the roll and the nozzle.

Since the resin is a photocurable resin, the operation was performed in a dark room until the resin droplets adhered to the roll surface. After the acid-resistant resin was applied, the resin was light-cured, and an aqueous solution of ferric chloride was spray-coated while rotating the roll to perform etching. The specific gravity of the ferric chloride solution was 1.45, and the temperature was controlled at 48 ° C. The etching rate at this time was about 4 to 6 μm / min. After the etching, the roll was washed, and the acid-resistant resin was removed with toluene. In this state, the center line average roughness Ra (JISB0601) and the peak count Pc (pieces / mm) were measured as the surface profile of the roll. That is,
The average wavelength of the irregularities and the pitch of the convex bodies. Note that P
c is the average interval S _{m of the} irregularities specified in JIS B0601.
Is the reciprocal of

Further, as a conventional example, the surface of the roll was processed by grid projection and electric discharge machining, and after processing, Ra and Pc were measured in the same manner as described above. Table 2 shows the machining conditions for grid projection, and Table 3 shows the conditions for electrical discharge machining.

[0057]

[Table 2]

[0058]

[Table 3]

FIG. 7 is a diagram showing the measurement results. As is clear from the figure, the roll surface processed by the method of the present invention has an uneven state in which the pitch is considerably reduced while having the same roughness as that of the roll surface subjected to conventional grid processing and electric discharge processing. Also, in the etching process,
When the resin liquid is applied in a state where the average particle diameter exceeds 20 μm (6, 7, 8), the pitch of the convex bodies is large.

Example 2 Roll No. 1 in Table 1 Under the conditions of 1, 3 and 5, the surface of the roll was newly applied in a patchy manner with an acid-resistant resin, and further subjected to chromium plating at a current density of 30 A / dm ² . A plating film was provided. Thereafter, the resin was removed with toluene.

The roll No. shown in Table 1 was used. No. 1 (etching roll) and No. 1 After applying an acid-resistant resin to the roll surface under the conditions of 1, a chrome-plated roll is prepared under the above conditions, and after removing the acid-resistant resin, the entire roll surface is further chromium-plated to form a plating film having a thickness of 15 μm. The provided roll was manufactured.

Using the roll thus obtained, the roll of the present invention prepared in Example 1, the conventional roll, and the roll of the comparative example, a SUS430-2B ferritic stainless steel sheet having a thickness of 0.5 mm and a width of 400 mm was used. The (18Cr) cold-rolled steel sheet was rolled, and the surface roughness and glossiness of the rolled steel sheet were measured. Table 4 shows the results.

[0063]

[Table 4]

As is clear from the table, when rolled by a roll satisfying the conditions of the present invention, a stainless steel sheet excellent in mattability was obtained. However, in the conventional example and the comparative example, the glossiness was high and the matteness was high. The steel plate is inferior.

[0065]

According to the method of the present invention, it is possible to form a steep unevenness on the surface of a roll, and by using this roll for rolling, it is possible to impart an excellent matting property to a stainless steel plate. it can. Its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the concept of mattness.

FIG. 2 is a diagram showing a surface profile of a roll surface by a conventional dulling method.

FIG. 3 is a view for explaining steps of a conventional lithography method.

FIG. 4 is a diagram showing a structure of a two-fluid nozzle.

FIG. 5 is a diagram showing an etching step according to the method of the present invention.

FIG. 6 is a view showing a profile of a roll surface processed by the method of the present invention.

FIG. 7 is a diagram showing a relationship between Ra and Pc on a roll surface subjected to dull processing.

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23F 1/00 C23F 1/00 102 B21B 27/00 C25D 5/02

Claims (3)

(57) [Claims] 1. A two-fluid nozzle sprays an acid-resistant resin liquid and a gas to spray a mist-like acid-resistant resin liquid in droplets having an average particle diameter of 20 μm or less on the surface of a metal roll, thereby applying a spot-like coating. And then etching the surface of the roll to which the acid-resistant resin is not attached. 2. A two-fluid nozzle sprays an acid-resistant resin liquid and a gas, and sprays a mist-like acid-resistant resin liquid in droplets having an average particle diameter of 20 μm or less onto the surface of a metal roll to apply a patch. And then metal plating the surface of the roll to which the acid-resistant resin is not adhered. 3. A method for processing the surface of a metal roll, comprising removing the acid-resistant resin from the surface of the roll processed by the method of claim 1 and plating the surface of the roll with metal.