JPH1099905A - Manufacture of aluminum or aluminum alloy plate having small optical anisotropy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably manufacturing an aluminum plate or an aluminum alloy plate which has small anisotropy (optical anisotropy) in reflection property of light in the rolling direction and the width direction perpendicular to the rolling direction on the surface of the plate and does not bring a problem about defective feeding of the plate. SOLUTION: At the time of manufacturing the aluminum plate or the aluminum alloy plate having objective thickness by further executing cold rolling after hot-rolling the aluminum ingot or the aluminum alloy ingot, the rolling operation of the final pass in such cold rolling is executed using rolling rolls on the surface of which a hard chromium plating film of 3-12μm thick is provided and the center-line average height Ra of the surface of which in the axial direction of the roll is 0.2-0.7μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an Al (aluminum, hereinafter the same) or Al alloy sheet having a small optical anisotropy, and more particularly, to light reflection in a rolling direction on a sheet surface and a width direction perpendicular to the rolling direction. The present invention relates to a method for producing an Al plate or an Al alloy plate with reduced anisotropy in characteristics.

[0002]

2. Description of the Related Art Conventionally, Al plates or Al alloy plates of various thicknesses have been obtained by hot rolling them using an Al ingot or an Al alloy ingot to give them, and then subjecting them to intermediate annealing depending on the application. Manufactured by cold rolling. Then, the plate material thus obtained is further subjected to various processings, treatments, and the like in accordance with the respective applications, thereby obtaining a target Al product.

By the way, the rolling roll used in the above-mentioned rolling operation usually has a circumferential streak attached at the time of the surface grinding. It is transferred in the rolling direction. In general, when the surface roughness, for example, roughness parameter: Ra, etc. of the grinding roll formed on the roll surface formed at the time of the roll grinding is roughened, the height difference of the unevenness of the roll surface becomes large. The grinding streaks become stronger and the surface roughness in the roll axis direction increases, and when finished finely, the grinding streaks become weaker and the surface roughness in the roll axis direction decreases. However, the strength of the grinding streaks mainly adjusts only the low-frequency component of the surface roughness, that is, the undulation in the waveform of the roughness curve, and reduces the fine roughness in the waveform of the roughness curve. The representative high-frequency component, that is, the minute unevenness does not change so much. On the other hand, the roughness in the rolling direction of the sheet is not so much influenced by the strength of the roll grinding streaks.

Accordingly, the difference in roughness between the rolling direction and the width direction (perpendicular to the rolling direction) of the roll becomes larger as the roll has stronger grinding lines, and therefore, the width of the rolled plate becomes larger. The diffuse reflection in the direction is a value greatly exceeding 100%, while in the rolling direction, it becomes very small, and the directionality of the reflection characteristic of the plate, that is, the optical anisotropy is large. There is an inherent problem of becoming.

[0005] When the anisotropy of the light reflection characteristics in the rolling direction and the width direction of the rolled sheet material, in other words, the optical anisotropy increases, various problems occur in the processing steps of such a rolled sheet material. It is to cause. For example, for a rolled sheet material, using an optical inspection device, when performing an inspection with light reflection characteristics, depending on the direction of light irradiation, if the reflection characteristics will change significantly,
The device is liable to malfunction and the normal inspection can no longer be performed. It has been recognized that such a malfunction of the apparatus is caused, for example, when the difference in diffuse reflectance between the rolling direction and the width direction exceeds 180.

[0006] For this reason, conventionally, in order to produce a plate material having a small optical anisotropy, it is necessary to weaken the roll grinding streaks. Specifically, the roll surface roughness is reduced to a small value. , It was dealt with. However, depending on the use of the rolled sheet material, it is necessary to change the surface roughness of the rolling roll.For example, in the use of a can lid material, in order to obtain a sheet material with low optical anisotropy, the roll surface roughness is reduced. It has been demanded to make the material finer, and in the use of the can body material, it has been required to make the surface roughness of the roll rough in order to prevent poor feeding of the plate material. as a result,
As the frequency of roll exchange of the rolling mill increases, the number of rolls held increases, and the frequency of roll grinding also increases.

[0007]

The present invention has been made in view of such circumstances, and an object thereof is to provide a light reflection characteristic of light in a rolling direction on a plate surface and in a width direction perpendicular to the rolling direction. It is an object of the present invention to provide a method capable of stably producing an Al plate or an Al alloy plate which has little anisotropy (optical anisotropy) and does not cause a problem of poor feeding of the plate.

[0008]

According to the present invention, in order to solve such a problem, an Al ingot or an Al alloy ingot is hot-rolled, and further cold-rolled to obtain an Al having an intended thickness.
When manufacturing a sheet or an Al alloy sheet, the final pass rolling operation in the cold rolling is performed by applying a hard chromium plating film having a thickness of 3 to 12 μm on the surface and performing a center line average roughness of the surface in the roll axis direction. Sa: Ra is 0.2 ~
The gist of the present invention is to provide a method for producing an Al or Al alloy sheet having low optical anisotropy, wherein the method is performed using a 0.7 mm-thick roll.

[0009] In short, in the production process of an Al plate or an Al alloy plate, the present inventors have found that the surface properties of the obtained plate material are greatly affected by the cold rolling, especially the final pass rolling. It became clear,
Then, in such a final pass rolling step, since the ground surface of the roll surface is transferred to the plate, in the present invention, a hard chrome plating film is formed on the roll surface at a predetermined thickness. At the same time, by maintaining the center line average roughness (Ra) of the surface in the roll axis direction within a predetermined range, it is possible to secure a certain surface roughness for slip prevention or the like and to increase the high frequency of the grinding streaks. It was possible to weaken the components, that is, micro-roughness, which weakened the grinding streaks in the direction perpendicular to rolling, which were generated by transferring it to the sheet surface. Thus, the difference in the light reflection characteristics of the plate surface, that is, the optical anisotropy, could be effectively reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In manufacturing an Al plate or an Al alloy plate having a predetermined thickness according to the present invention,
The corresponding Al ingot or Al alloy ingot is used, hot-rolled according to a conventional method, and then cold-rolled. In the present invention, the final pass in this cold-rolling is performed. As a rolling roll that performs a rolling operation,
The center line average roughness of the surface in the roll axis direction having a hard chromium plating film having a thickness of 3 to 12 μm on the surface: R
The rolling roll having a of 0.2 to 0.7 μm is used, thereby reducing the plate surface streaks caused by the transfer of the grinding streaks of the roll and effectively reducing the diffuse reflection in the plate width direction. It was possible.

When the thickness of the hard chromium plating film applied to the surface of the rolling roll exceeds 12 μm, plating peeling occurs at the boundary between the roll surface substrate and the plating film and the plating film portion is peeled off. If the thickness is less than 3 μm, the effect of eliminating the high frequency component of the grinding streaks on the roll surface substrate and the effect of improving the wear resistance cannot be expected. In addition, when the center line average roughness Ra of the surface of the roll in which the hard chromium plating film is formed in the roll axis direction is larger than 0.7 μm, grinding streaks appear strongly and the optical anisotropy appears. This is because the effect of reducing the property is canceled out, and if it is smaller than 0.2 μm, a slip is easily caused between the roll and the rolled material, and the rolling and the feeding of the plate become unstable. In particular, in order to effectively avoid the occurrence of these problems and effectively achieve the object of the present invention, it is desirable that the hard chromium plating film be formed in a thickness of 4 to 7 μm, , The center line average roughness of the surface: Ra is 0.3 to 0.5.
It is desirable that the thickness be 6 μm.

[0012] The hard chromium plating film as described above can be formed by using C
It can be easily formed on the ground surface of the rolled base material by electroplating using an rO ₃ -SO ₄ bath or a CrO ₃ -SO ₄ -fluoride bath, Generally, by adjusting the plating time, the thickness of the formed plating film is adjusted.

Further, the center line average roughness of the surface of the roll surface after the plating treatment in the roll axis direction is Ra.
Is set to 0.2 to 0.7 μm, the R
a is the Ra of the hard chromium plating film formed thereon
The surface of the roll substrate is
The surface is adjusted by grinding (polishing) processing so that the center line average roughness of the surface in the roll axis direction: Ra is 0.2 to 0.7 μm, and then hard chromium having a predetermined thickness is formed thereon. A technique of forming a plating film will be adopted.

The Al plate or the Al alloy plate having a predetermined thickness obtained by performing the final pass rolling of the cold rolling using the rolling roll coated with such a hard chromium plating film is rolled. The anisotropy of the light reflection characteristics in the direction and the width direction perpendicular to the direction is effectively reduced, and this limits the malfunction of the optical inspection device in the processing steps and the like after such a plate material. It can be advantageously achieved that the diffuse reflectance difference is 180 or less.

Incidentally, the diffuse reflectance referred to herein is the one shown in FIG.
As shown in the schematic diagram of the measurement, light irradiated from a direction of 45 ° with respect to the plate surface is 0 ° (with respect to the plate surface,
The ratio of diffuse reflection in the (perpendicular) direction is expressed as a percentage of the value on a perfect diffuse reflection surface (surface on which irradiation light is uniformly reflected in all directions). Are determined in the rolling direction of the sheet material and in the width direction perpendicular to the rolling direction, and the optical anisotropy is evaluated based on the difference between them.

[0016]

EXAMPLES In order to clarify the present invention more specifically, some examples of the present invention will be shown below.
It goes without saying that the present invention is not subject to any restrictions by the description of such embodiments. Further, in addition to the following examples, the present invention may further include various changes and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention, in addition to the specific description described above. , Improvements and the like can be added.

First, various Al alloy rolled materials having a thickness of 2 mm were prepared from the corresponding Al alloy ingots by a normal hot rolling operation. On the other hand, with respect to the roll base surface whose surface properties (Ra) are variously varied by polishing,
Using a plating bath containing chromic anhydride and sodium silicate fluoride, electroplating is carried out at a temperature of 50 to 60 ° C by ordinary industrial chromium plating method, and hard plating of various thicknesses corresponding to the plating time A rolling roll (work roll) on which a chromium plating film was formed was produced. Then, using this rolling roll, a cold rolling operation was performed on the rolled material prepared above under the following conditions, and the sheet thickness was reduced to 0.3.
mm Al alloy plate was obtained. -Cold rolling conditions- Rolling roll diameter: 200.470 mmφ Pass schedule: Rolling in 3 to 5 passes to 0.3 mm Rolling speed: 100 to 1000 m / min Rolling oil viscosity: 4 centistokes

With respect to the various cold rolled sheets thus obtained, the diffuse reflectance in the rolling direction and the width direction is shown in FIG.
Gloss meter manufactured by Murakami Color Research Laboratory according to the measurement method as follows:
Each was measured in the form GM3D, and the results of the obtained difference in diffuse reflectance and evaluation of optical anisotropy are shown in Table 1 below. In addition, the properties of each roll after rolling and the feeding state of the plate in the processing step after the obtained various cold-rolled plates were examined, and the results are shown in Table 1 below.

[0019]

[Table 1]

As is clear from the results in Table 1, in the examples No. 1 to No. 6 according to the present invention, the thickness of the hard plating film of the rolling roll is 3 to 12 μm and the surface in the roll axis direction is Center line average roughness: Ra is 0.2
When the thickness is within the range of about 0.7 μm, the difference in diffuse reflectance is small without causing partial peeling or abrasion of the plating film and without causing feeding failure of the plate. A plate material having a small optical anisotropy can be advantageously obtained.

On the other hand, as shown in the comparative examples of Nos. 8 to 15, in the case of using a rolling roll not subjected to hard chrome plating, the optical anisotropy of the obtained plate material is reduced. In the comparative examples of No. 7 and No. 16 in which Ra in the roll axis direction was extremely reduced, poor feeding (slip) of the plate occurred, causing a problem in the post-processing step. Was to do. Furthermore,
Even in the case of a roll having a hard chromium plating film, if the thickness of the plating film is too thin or too thick, the plating film is partially worn out after rolling, or causes peeling of the plating film. There is a problem, and No.
As can be seen from the comparative example No. 17, even when the hard chromium plating film is applied, it is recognized that if the Ra in the roll axis direction is too large, the optical anisotropy becomes large.

[0022]

As is apparent from the above description, according to the method of the present invention, the difference between the reflection characteristics in the rolling direction and the width direction perpendicular to the rolling direction, that is, the Al plate or the Al alloy plate having little optical anisotropy. Can be manufactured stably without changing the roughness of the roll.
The problem of introducing such an optical inspection apparatus in a later processing step of such a plate material can be effectively avoided, and the frequency of roll exchange and the frequency of roll grinding can be reduced. Reduction in production efficiency,
Furthermore, cost reduction can be effectively achieved, and there is a great technical significance of the present invention.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing a method of measuring diffuse reflectance.

Claims (1)

[Claims] 1. An aluminum ingot or an aluminum alloy ingot is hot-rolled, and then cold-rolled to obtain a target thickness of A.
When manufacturing a 1 plate or an Al alloy plate, the final pass rolling operation in such cold rolling is performed on a surface of 3 to 12 μm.
And a center line average roughness of the surface in the roll axis direction: Ra is 0.2
A method for producing an Al or Al alloy plate having low optical anisotropy, wherein the method is performed using a rolling roll having a diameter of 0.7 μm.