JP2017081149A - Small sized electronic device case, molding method thereof and aluminum alloy rolled laminate sheet material for small sized electronic device case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small sized electronic device case capable of being molded by contraction processing at good efficiency and low cost, hardly generating molding defects, having no scratch on a surface by molding and having excellent appearance.SOLUTION: An aluminum alloy rolled laminate sheet material is used for molding a small sized electronic device case by contraction molding and is constituted by an aluminum alloy rolled sheet material having 0.2% bearing force of 200 MPa or more and a coating material laminated on at least one surface of both surfaces of the aluminum alloy rolled sheet material. The coating material consists of one of a synthetic resin film and a laminate wherein the synthetic resin film is laminated on both surfaces of a metal foil. The aluminum alloy rolled sheet material has a fibrous crystal structure extending in a direction orthogonal to a thickness direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a case of a small electronic device such as a tablet terminal, a portable communication terminal device, a notebook personal computer, a mobile phone, a portable music device, a digital camera, and a method for forming the same, and an aluminum alloy rolled laminate used as a molding material for the case It relates to plate materials.

Conventionally, as a case of a small electronic device, a case formed by cutting (entirely cutting out) a thick plate-like aluminum alloy extruded material is known (for example, see Patent Document 1 below).
The above case can be suitably used as a small electronic device case because it has excellent appearance, precision and strength.

  In general, drawing is also widely performed as means for forming a product having a predetermined shape from a metal plate such as an aluminum alloy plate.

JP 2012-246555 A

  However, in the case of a small electronic device case formed by cutting, since it takes a long time to cut the material, the manufacturing efficiency is low, and a large amount of cutting waste is generated along with the processing, and this is recovered. However, since a lot of energy is required, there is a problem that the cost becomes high as a result.

On the other hand, in the case of drawing, since molding is performed in a short time, the manufacturing efficiency is excellent, and there is no generation of debris accompanying the processing, so that it can be manufactured at low cost. However, the form of the small electronic device case is generally provided with a bottom wall that is substantially rectangular when viewed from above and a side wall that rises from the periphery of the bottom wall. If the case having such a configuration is to be molded by drawing, there is a high possibility that the corner portion of the side wall is cracked, resulting in molding failure.
In addition, in the case of drawing, the surface of the metal plate material is in sliding contact with the mold, which may cause damage to the surface of the molded product and impair the appearance of the product.

  An object of the present invention is to provide a small electronic device case that can be molded efficiently and at low cost by drawing processing, is less prone to molding defects, has no scratch on the surface, and has an excellent appearance. There is.

  In order to achieve the above object, the present invention comprises the following aspects.

1) An aluminum alloy rolled laminated sheet for forming a small electronic device case by drawing, and at least one of both surfaces of an aluminum alloy rolled sheet having a 0.2% proof stress of 200 MPa or more and an aluminum alloy rolled sheet It is composed of a covering material laminated on one surface, and the covering material is a small size composed of either a synthetic resin film or a laminate in which a synthetic resin film is laminated on both surfaces of a metal foil. Aluminum alloy rolled laminate for electronic device cases.

2) The aluminum alloy rolled laminated sheet material for small electronic device cases according to 1) above, wherein the aluminum alloy rolled sheet material has a fibrous crystal structure extending in a direction perpendicular to the thickness direction.

3) Al—Mn—Mg based alloy consisting of aluminum alloy rolled sheet material, Mn: 0.2 to 0.7 mass%, Mg: 2.0 to 5.0 mass%, balance Al and inevitable impurities, Si: 0 .2 to 0.8 mass%, Mg: 0.4 to 1.2 mass%, Al—Si—Mg based alloy composed of the balance Al and inevitable impurities, and Zn: 4.0 to 6.5 mass%, Mg : Aluminum alloy for small electronic device cases according to 1) or 2) above, which is made of any one aluminum alloy of Al-Zn-Mg alloys composed of 0.5 to 3.0% by mass, the balance Al and inevitable impurities Rolled laminated sheet material.

4) The aluminum alloy rolled laminated sheet material for a small electronic device case according to any one of 1) to 3) above, wherein the thickness of the covering material is 0.05 to 1.5 times the thickness of the aluminum alloy rolled sheet material.

5) The aluminum alloy rolled laminated sheet material for a small electronic device case according to any one of 1) to 4) above, wherein the aluminum alloy rolled sheet material has a thickness of 0.5 to 3.5 mm.

6) A covering material made of a polyester resin film or a polyamide resin film having a thickness of 50 to 100 μm is laminated on the outer surface of the small electronic device case among both surfaces of the aluminum alloy rolled sheet material, 1) to 5) above Aluminum alloy rolled laminated sheet material for any one of the small electronic device cases.

7) A covering material made of a polyethylene resin film, a polypropylene resin film or a polyamide resin film having a thickness of 10 to 100 μm is laminated on a surface which is an inner surface of a small electronic device case among both surfaces of an aluminum alloy rolled plate material. The aluminum alloy rolled laminated sheet material for any one of small electronic device cases.

8) A coating obtained by drawing the aluminum alloy rolled laminated sheet for small electronic device cases according to any one of 1) to 7) above, wherein at least one of the inner and outer surfaces is made of a synthetic resin film or a laminate. A small electronic device case with a covering, covered with a material.

9) After drawing the aluminum alloy rolled laminated sheet material for small electronic device cases according to any one of 1) to 7) above, the covering material covering at least one of the inner and outer surfaces is removed. Small electronic equipment case.

10) The above-described 9), which includes a bottom wall and a side wall rising from the peripheral edge of the bottom wall, the side wall height is 0.5 to 25 mm, and the side wall angle is 90 to 150 °. Small electronic equipment case.

11) A method for forming a small electronic device case, wherein the aluminum alloy rolled laminated sheet for the small electronic device case according to any one of 1) to 7) is drawn.

According to the aluminum alloy rolled laminated sheet material for a small electronic device case of 1) above, a 0.2% proof stress of 200 MPa or more is used as the aluminum alloy rolled sheet material as the material of the case. Strength is secured.
Moreover, according to the aluminum alloy rolled laminated sheet material of 1) above, a laminated structure in which a synthetic resin film or a synthetic resin film is laminated on both surfaces of a metal foil on at least one surface of both surfaces of the aluminum alloy rolled sheet material. Since the cover material with low frictional resistance is laminated, the side wall of the case formed by drawing is not wrinkled or cracked at the corner of the side wall, and the occurrence of molding defects is suppressed. In addition, the surface of the case is prevented from being damaged by contact with the mold, and the appearance of the case is not impaired.

  According to the aluminum alloy rolled laminated sheet material for small electronic device cases of 2) above, since the aluminum alloy rolled sheet material has a fibrous crystal structure extending in a direction orthogonal to the thickness direction, the strength of the sheet material against bending And molding defects such as wrinkles and cracks are unlikely to occur.

  According to the aluminum alloy rolled laminated sheet material for small electronic device cases of 3) above, the aluminum alloy rolled sheet material is an Al—Mn—Mg based alloy, Al—Si—Mg based alloy, Al—Zn—Mg having the above composition. Since it is made of any one aluminum alloy among the system alloys, the forming by drawing is performed well, and a case with high precision and strength and excellent appearance is obtained.

According to the aluminum alloy rolled laminated sheet material for small electronic device cases of 4) above, since the thickness of the covering material is 0.05 to 1.5 times the thickness of the aluminum alloy rolled sheet material, there are the following problems: Avoided.
That is, when the thickness of the coating material is less than 0.05 times the thickness of the aluminum alloy rolled sheet material, the coating material is broken and the portion where the molded product comes into contact with the mold is damaged. On the other hand, even if the thickness of the covering material exceeds 1.5 times the thickness of the aluminum alloy rolled sheet material, no further effect is obtained, and only the cost is increased.

According to the aluminum alloy rolled laminated sheet material for small electronic device cases of 5) above, since the thickness of the aluminum alloy rolled sheet material is 0.5 to 3.5 mm, the following problems are avoided.
That is, when the thickness of the aluminum alloy rolled plate material is less than 0.5 mm, the strength of the final product is insufficient. On the other hand, if the thickness of the rolled aluminum alloy sheet exceeds 3.5 mm, the radius of curvature (R) of the bent portion or corner portion becomes too large.

  According to the aluminum alloy rolled laminated sheet material for small electronic device cases of 6), the following effects are exhibited. That is, when a compact electronic device case is formed by drawing an aluminum alloy rolled laminated sheet material, the outer surface of the small electronic device case is partially squeezed by a mold. If a polyester resin film or a polyamide resin film having a thickness of 50 to 100 μm is used as the covering material to be covered, the surface of the molded product is surely avoided from being damaged by ironing of the mold. In addition, the increase in cost due to the film thickness being too large can be suppressed, and further, the rigidity of the film can be prevented from rising and peeling from the bent portion of the case. .

  According to the aluminum alloy rolled laminated sheet material for small electronic device case of 7), the following effects are exhibited. That is, when a compact electronic device case is formed by drawing aluminum alloy rolled laminated sheet material, the surface that is the inner surface of the small electronic device case is not squeezed by the mold, but in the concave direction. Since a part to be bent is formed, if a polyethylene resin film, polypropylene resin film or polyamide resin film having a thickness of 10 to 100 μm is used as a covering material for covering the same surface, the rigidity of the film is too large. It is possible to avoid floating and peeling from the bent portion, and it is possible to avoid a situation in which the radius of curvature (R) of the bent portion of the case becomes large and a sharp shape cannot be obtained.

According to the small electronic device case with a covering material of 8), the aluminum alloy rolled plate material is formed satisfactorily by drawing, and since the surface is not damaged during forming, it has high precision and strength and A case with a beautiful appearance can be obtained.
In addition, according to the above-mentioned 8) small electronic device case with a covering material, since the surface of the case is covered with the covering material, the surface is prevented from being damaged during storage or transportation.

  According to the small electronic device case of the above 9), the aluminum alloy rolled plate material is formed well by drawing, and the surface is not scratched during forming, storage or transportation. A case having strength and a beautiful appearance can be obtained.

According to the small electronic device case of the above 10), the height of the side wall is 0.5 to 25 mm, and the angle of the side wall with respect to the bottom wall is 150 °. Therefore, the following problems are avoided.
That is, if the height of the side wall is less than 0.5 mm, the number of cutting parts increases in the subsequent process. On the other hand, if the height of the side wall exceeds 25 mm, the thickness of the small electronic device increases, which is not preferable.
Further, when the angle of the side wall with respect to the bottom wall is less than 90 °, that is, when the side wall is inclined inward, wrinkles are generated at the corner portion, and the processing becomes difficult. On the other hand, if the angle of the side wall with respect to the bottom wall exceeds 150 °, the depth of the case becomes shallow, and the capacity for accommodating the components of the small electronic device decreases.

  According to the molding method of a small electronic device case of the above 11), a small electronic device case having high precision and strength and exhibiting a beautiful appearance can be efficiently molded at low cost by drawing.

It is a partial expanded sectional view which shows the layer structure of the aluminum alloy rolling laminated sheet material for small electronic device cases by this invention. It is a vertical sectional view which shows sequentially the process of shape-drawing the board | plate material and shape | molding a small electronic device case. It is a perspective view of the small electronic device case by this invention. It is a perspective view for showing the section direction at the time of bending the aluminum alloy rolled sheet material and observing the fibrous crystal structure of the section. It is a microscope picture of the cross section (the cross-sectional direction with respect to a rolling direction: 90 degrees) of the bending material (inner round: 0 mm) of the aluminum alloy rolled sheet material. It is a microscope picture of the cross section (cross-sectional direction with respect to a rolling direction: 90 degrees) of the bending material (inner radius: 0.4 mm) of the aluminum alloy rolled sheet material. It is a microscope picture of the cross section (cross-sectional direction: 0 degree with respect to the rolling direction) of the bending material (inner round: 0 mm) of the aluminum alloy rolled sheet material. It is a microscope picture of the cross section (cross-sectional direction: 0 degree with respect to the rolling direction) of the bending material (inner radius: 0.4 mm) of the aluminum alloy rolled sheet material.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a layer structure of an aluminum alloy rolled laminated sheet material (1) for a small electronic device case according to the present invention.
As shown in the figure, the aluminum alloy rolled laminated sheet (1) for a small electronic device case includes an aluminum alloy rolled sheet (2) and a covering material (3) (4) laminated on both sides of the aluminum alloy rolled sheet (2). It consists of and.

As the aluminum alloy rolled sheet (2), a 0.2% proof stress is 200 MPa or more, preferably 250 MPa or more, more preferably 300 MPa or more. Thereby, the intensity | strength of a desired case is obtained. In addition, as the aluminum alloy rolled sheet (2), one having an elongation at break of 5% or more and 20% or less is suitably used. Thereby, the moldability of the drawing process is improved. Here, “0.2% proof stress” and “breaking elongation” are based on a tensile test parallel to the rolling direction using No. 5 test piece defined in JIS Z2241-2011.
The aluminum alloy rolled sheet (2) has a fibrous crystal structure extending in a direction orthogonal to the thickness direction.
The fibrous crystal structure is formed by subjecting a homogenized aluminum alloy cast soul to heat treatment under a predetermined condition after hot rolling, and then cold rolling. The said heat processing is performed by hold | maintaining at 200-400 degreeC for 1 hour or more. By the heat treatment, Mg ₂ Si can be finely and uniformly precipitated, and processing strain existing in the rolled material can be reduced. It is possible to obtain a high-strength rolled aluminum alloy sheet within a range that does not impair subsequent workability by work hardening by subsequent cold working.
The conditions for the homogenization treatment of the aluminum alloy casting soul are not particularly limited, and it is preferably performed at 500 ° C. or more for 2 hours or more according to a conventional method.
In hot rolling, the same effect as quenching is obtained by a temperature drop during rolling at a predetermined temperature condition in an arbitrary pass process. Accordingly, the material temperature before the pass needs to be a temperature at which Mg and Si can be kept in a solid solution state, and is set to 350 to 440 ° C. In order to set the pass rising temperature in the temperature range of 200 to 400 ° C., forced cooling such as high pressure shower water cooling may be performed immediately after hot rolling. Further, in order to obtain a quenching effect, the cooling rate between passes is 50 ° C./min or more, the pass rising temperature is 250 to 340 ° C., the pass rolling rate is 50 m / min or more, and the ascending plate thickness is 10 mm or less. .
In cold rolling, the rolling reduction is 30% or more in order to obtain a predetermined strength by work hardening. A preferable rolling reduction is 50% or more.
Furthermore, the cold-rolled alloy plate can be finally annealed at a temperature of 130 to 150 ° C., if necessary. By performing the heat treatment at a low temperature, the strength can be further improved by age hardening, and the elongation can be improved. It also has the effect of stabilizing mechanical properties.
As the aluminum alloy rolled sheet (2), one made of any of the following aluminum alloys is preferably used.
i) Al—Mn—Mg-based alloy containing Mn: 0.2 to 0.7% by mass, Mg: 2.0 to 5.0% by mass, the balance being Al and inevitable impurities ii) Si: 0.2 -0.8 mass%, Mg: 0.4-1.2 mass%, Al-Si-Mg-based alloy iii consisting of the balance Al and inevitable impurities iii) Zn: 4.0-6.5 mass%, Mg: Al-Zn-Mg-based alloy containing 0.5 to 3.0% by mass, the balance being Al and inevitable impurities. 4 to 0.6 mass%, Mg: 4.0 to 4.9 mass%, Fe: 0.4 mass% or less, Cr: 0.05 to 0.25 mass%, Zn: 0.25 mass% or less The aluminum alloy which contains and consists of remainder Al and an unavoidable impurity is mentioned.
As the alloy of ii), Si: 0.2 to 0.6 mass%, Mg: 0.45 to 0.9 mass%, Fe: 0.35 mass% or less, Cr: 0.1 mass% or less, Zn: An aluminum alloy containing 0.1% by mass or less and composed of the balance Al and inevitable impurities may be mentioned.
As the alloy of the above iii), Si: 0.4 mass% or less, Mg: 2.1-2.9 mass%, Fe: 0.5 mass% or less, Cu: 1.2-2.0 mass%, Examples include an aluminum alloy containing Mn: 0.3% by mass or less, Cr: 0.18 to 0.28% by mass, Zn: 5.1 to 6.1% by mass, and the balance Al and inevitable impurities.
Among these, Si: 0.2-0.6 mass%, Mg: 0.45-0.9 mass%, Fe: 0.35 mass% or less, Cr: 0.1 mass% or less, Zn: An aluminum alloy rolled sheet (2) made of an aluminum alloy containing 0.1% by mass or less and the balance Al and inevitable impurities is suitable as a molding material for a small electronic device case.
Further, the thickness of the aluminum alloy rolled sheet (2) to be used is appropriately set according to the molding conditions, the size of the case as a molded product, etc., but is preferably 0.5 to 3.5 mm, more preferably 0. .8 to 1.2 mm.

The covering materials (3) and (4) improve the formability when the aluminum alloy rolled plate (2) is drawn, reduce the use of lubricant during forming, and in addition, the plate (2 ) To prevent the surface from being scratched, and further to protect the case surface after molding the case, for example, during storage or transportation.
As the covering materials (3) and (4), synthetic resin films (32), (33), (42), and (43) are laminated on both sides of the metal foils (31) and (41) as shown in FIG. In some cases, the laminates (3) and (4) are used, and as shown in FIG. 1B, synthetic resin films (30) and (40) are used.
In the aluminum alloy rolled laminated sheet material (1) for the small electronic device case of the first aspect shown in FIG. 1 (a), as the metal foils (31) and (41) of the laminated bodies (3) and (4) constituting the covering material Examples include aluminum foil, stainless steel foil, and copper foil. In addition, as the synthetic resin films (32), (33), (42) and (43) of the laminates (3) and (4), unstretched polypropylene resin film (CPP), polyethylene terephthalate resin film (PET), nylon resin film ( Ny), a polyimide resin film (PI), a polyethylene resin film (PE), or a stretched film thereof. Lamination of metal foil (31) (41) and synthetic resin film (32) (33) (42) (43) is cured with, for example, polyester urethane resin (PAUR), acrylic resin, acid-modified polyolefin resin (APO), etc. It is carried out through an adhesive layer (not shown) made of an agent.
In the aluminum alloy rolled laminated sheet material (1) for a small electronic device case of the second aspect shown in FIG. 1 (b), the synthetic resin films (30) and (40) constituting the covering materials (3) and (4) are: For example, a polypropylene resin film, a polyester resin film, a polyamide resin film, a polyimide resin film, or a polyethylene resin film is used. Preferably, a biaxially stretched polyethylene terephthalate resin film (PET), a biaxially stretched nylon resin film (ONy), or polyethylene is used. Any one of a resin film, a biaxially stretched polyamide resin film, a biaxially stretched polypropylene resin film (OPP), an unstretched polypropylene resin film (CPP), and an unstretched nylon resin film (CNy) is used.
Also, the covering material (3) to be laminated on the outer surface of the small electronic device case (the lower surface in FIG. 1 (b)) of both surfaces of the aluminum alloy rolled plate (2) is a synthetic material having a thickness of 10 to 200 μm. A resin film (30) is preferably used, and the covering material (4) to be laminated on the surface (the upper surface in FIG. 1 (b)) of the small electronic device case has a synthetic resin thickness of 10 to 100 μm. A film (40) is preferably used.
More preferably, the covering material (3) laminated on the surface (the lower surface in FIG. 1 (b)) which is the outer surface of the small electronic device case out of both surfaces of the aluminum alloy rolled sheet (2) has a thickness of 50 to 100 μm. Of a biaxially stretched polyethylene terephthalate resin film (PET), a biaxially stretched polyethylene naphthalate resin film (PEN), or a biaxially stretched film. 6-Nylon resin film (ONy) (30). A film having a tensile strength of 180 to 330 MPa and a tensile elongation at break of 80 to 180% can be appropriately used for the film (30). Especially, the film (30) whose ratio of MD / TD of tensile strength or tensile breaking elongation is 0.8-1.2 can be used conveniently.
Further, the covering material (4) laminated on the surface (upper surface in FIG. 1 (b)) of the aluminum alloy rolled sheet (2) which is the inner surface of the small electronic device case has a thickness of 10 to 100 μm (more preferably Is preferably composed of a polyethylene resin film, a polypropylene resin film or a polyamide resin film, more preferably an unstretched polyethylene resin film, an unstretched polypropylene resin film (CPP), or a stretched polypropylene resin film (OPP). Or a stretched nylon resin film (ONy) (40). A film having a Young's modulus of 30 to 400 MPa can be suitably used for the film (40).
The covering material only needs to be laminated on at least one surface of both sides of the aluminum alloy rolled sheet material (2), more specifically, the surface constituting the outer surface of the case. From the viewpoint of protecting the case surface after forming, it is preferable that the aluminum alloy rolled sheet material (2) is laminated on both surfaces as shown in FIG.
When laminating the covering material on both surfaces of the aluminum alloy rolled sheet (2), the two covering materials laminated on each surface may be the same or different materials / thicknesses.
When the bending strength of the aluminum alloy rolled sheet (2) is small or the thickness is small, the synthetic resin films (30) and (40) may be used as the covering material (see FIG. 1 (b)). If the bending strength of the rolled alloy sheet (2) is large or the thickness is large, using a synthetic resin film as the coating material may break during drawing and cause wrinkles on the surface of the molded product. The body (3) (4) is preferable (see FIG. 1 (a)).
In view of the fact that the covering materials (3) and (4) are laminated on the surface of the rolled aluminum alloy sheet (2), it is necessary to remove the covering materials (3) and (4) from the surface after the case is formed. As shown, it is preferably carried out through the pressure-sensitive adhesive layers (34) and (44). For the pressure-sensitive adhesive layers (34) and (44), for example, urethane-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, and rubber-based pressure-sensitive adhesives are used. The adhesive strength of the adhesive layers (34) and (44) to the aluminum alloy rolled sheet (2) is preferably 0.5 to 15 N / 25 mm (more preferably 1 to 10 N / 25 mm). Here, “adhesive strength” is expressed by 180 ° peeling adhesive strength in accordance with JIS Z 0237: 2000. When the adhesive strength of the adhesive layers (34) and (44) is less than 0.5 N / 25 mm, the aluminum alloy rolled sheet (2) is coated when handling the aluminum alloy rolled laminated sheet (1) before forming the case. While the materials (3) and (4) are easily peeled off, if the adhesive strength of the adhesive layers (34) and (44) exceeds 15 N / 25 mm, the covering materials (3) and (4) are peeled off after the case is molded. In addition, the workability at the time of performing may be reduced, and a part of the pressure-sensitive adhesive may remain on the surface of the case, resulting in problems in subsequent polishing or the like.
The thickness of the covering materials (3) and (4) is preferably 0.05 to 1.5 times the thickness of the aluminum alloy rolled sheet (2), more preferably 0.2 to 1. 0 times.

FIG. 2 shows a process of forming a small electronic device case by drawing the aluminum alloy rolled laminate (1).
First, a substantially rectangular aluminum alloy rolled laminated sheet material (1) cut to a predetermined dimension is set on the upper surface of a fixed female die (die) (5) on the lower side of the die (see FIG. 2 (a)). . Here, at least the lower surface of the upper and lower surfaces of the aluminum alloy rolled laminated sheet material (1), that is, the surface of the lower coating material (3), for example, a silicone-based lubricant, mineral oil, or synthetic petroleum-based material It is preferable to apply a lubricant composed of a lubricant, whereby the moldability is further improved.
Then, when the movable male die (punch) (6) on the upper side of the mold is lowered, the portion excluding the peripheral portion of the aluminum alloy rolled laminated sheet material (1) is added downward at the tip of the male die (6). As a result, the straight portion of the peripheral edge is bent upward, and the corner portion of the peripheral edge is drawn (see FIG. 2B). At this time, since both surfaces of the aluminum alloy rolled sheet (2) are covered with the covering materials (3) and (4), generation of wrinkles is suppressed, and as a result, cracks do not occur. Further, since the surface of the aluminum alloy rolled sheet (2) does not come into direct contact with the female mold (5) and the male mold (6), it is not rubbed and scratched.
Thus, the small electronic device case (20) with the covering materials (3) and (4) is obtained. Since the surface of the small electronic device case (20) is covered with the covering material (3) (4), it will not be damaged by contact with other objects during storage or transportation, and will be kept in a beautiful state. Is done.

FIG. 3 shows a small electronic device case (20). This case (20) is partly cut after removing the covering material (3) (4) from both the inside and outside of the small electronic device case (20) with the covering material (3) (4). It is obtained by applying and finish-molding, and further anodizing the surface.
The small electronic device case (20) includes a bottom wall (21) having a substantially square shape when seen from the plane and four side walls (22) rising from the four sides of the bottom wall (21). The ends of adjacent side walls (22) are continuous, and the bottom wall (21) is surrounded by the four side walls (22).
The height of the side wall (22) (in other words, the molding height) is 0.5 to 25 mm, preferably 1 to 15 mm, and more preferably 2 to 10 mm.
The angle of the side wall (22) with respect to the bottom wall (21) is 90 to 150 ° (the one shown is about 90 °), preferably 90 to 120 °, more preferably 90 to 100 °.
The corners (22a) of the side wall (22) are also rounded at the boundary between the bottom wall (21) and the side wall (22). In these round portions, the fibrous crystal structure extends along the round.

The fibrous crystal structure can be confirmed by observing the cross section of the aluminum alloy rolled plate (2) or the case (20) formed by drawing the aluminum alloy rolled plate (2) using a polarizing microscope.
Preferably, the fibrous crystal structure is preferably observed even in a cross section cut in an arbitrary direction such as 0 °, 90 °, 45 °, and 135 ° with respect to the rolling direction of the aluminum alloy rolled sheet. The same can be observed in the bent portion and the corner portion.
Specifically, for example, as shown in FIGS. 4 (a) and 4 (b), a rolled aluminum alloy sheet (2) having a thickness of 0.25 mm is bent so that the inner radius is 0 mm or 0.4 mm. For these bending materials, a cross section cut in a direction (Y) of 90 ° (perpendicular) or 0 ° (parallel) with respect to the rolling direction (X) is observed with a polarizing microscope. Then, as can be seen from the micrographs of FIGS. 5 to 8, the inner radius is 0 mm, the cross-sectional direction with respect to the rolling direction: 90 ° (FIG. 5), the inner radius is 0.4 mm, and the cross-sectional direction with respect to the rolling direction is 90 ° (FIG. 6). ), Inner radius: 0 mm, sectional direction with respect to rolling direction: 0 ° (FIG. 7), inner radius: 0.4 mm, sectional direction with respect to rolling direction: 0 ° (FIG. 8) The structure extends in a direction orthogonal to the thickness direction of the plate material so as to be along the radius.

  Next, specific examples of the present invention will be described. However, the present invention is not limited to these examples.

<Example 1>
Si: 0.2-0.6 mass%, Mg: 0.45-0.9 mass%, Fe: 0.35 mass% or less, Cr: 0.1 mass% or less, Zn: 0.1 mass% or less The aluminum alloy casting soul containing the balance Al and inevitable impurities was homogenized at 580 ° C. for 10 hours, then face-cut, preheated at 500 ° C., and hot rolling was started. The final pass start temperature of hot rolling was 400 ° C., and after the pass, cooling was performed at a rate of 80 ° C./min. Thereafter, heat treatment was performed at 240 ° C. for 4 hours. Thereafter, cold rolling was performed at a reduction rate of 86%. Thus, a 1 mm-thick aluminum alloy rolled sheet material having a 0.2% proof stress of 310 MPa and a breaking elongation of 7% was obtained.
When the cross section of the plate was observed with an optical microscope and a deflecting lens, a fibrous crystal structure extending in a direction perpendicular to the thickness direction was observed.
And, on the lower surface of the aluminum alloy rolled plate constituting the outer surface of the small electronic device case, as a covering material, an unstretched polypropylene resin film with a thickness of 30 μm is coated on one surface of an aluminum foil with a thickness of 120 μm and polyester urethane resin and hexanemethylene isocyanate. A laminate formed by laminating an unstretched polypropylene resin film having a thickness of 200 μm on the other side with an adhesive layer and an adhesive layer made of an acrylic pressure-sensitive adhesive layer. And laminated.
Further, a nylon resin film having a thickness of 30 μm was laminated as a covering material on the upper surface of the aluminum alloy rolled plate constituting the inner surface of the small electronic device case via an adhesive layer made of an acrylic adhesive.
The aluminum alloy rolled laminated sheet material thus obtained was cut into a substantially rectangular shape having a length of 150 mm, a width of 82 mm, and a corner radius of 14.5 mm to produce a molding material of Example 1.

<Example 2>
Si: 0.4 mass% or less, Mn: 0.4-0.6 mass%, Mg: 4.0-4.9 mass%, Fe: 0.4 mass% or less, Cr: 0.05-0. Aluminum alloy casting soul containing 25% by mass and Zn: 0.25% by mass or less and comprising the balance Al and inevitable impurities is homogenized at 580 ° C. for 10 hours and then face-cut, and preheated at 500 ° C. And hot rolling was started. The final pass start temperature of hot rolling was 400 ° C., and after the pass, cooling was performed at a rate of 80 ° C./min. Thereafter, heat treatment was performed at 240 ° C. for 4 hours. Then, after cold rolling at a reduction rate of 79%, final annealing was performed at 130 ° C. for 4 hours. Thus, an aluminum alloy rolled sheet material having a thickness of 1.5 mm having a 0.2% proof stress of 210 MPa and a breaking elongation of 7% was obtained.
When the cross section of the plate was observed with an optical microscope and a deflecting lens, a fibrous crystal structure extending in a direction perpendicular to the thickness direction was observed.
And the nylon resin film of thickness 90micrometer was laminated | stacked through the adhesive layer which consists of an acrylic adhesive as a coating | covering material on the upper and lower surfaces of the aluminum alloy rolled sheet material, respectively.
The aluminum alloy rolled laminated sheet material thus obtained was cut into a substantially rectangular shape having a length of 150 mm, a width of 82 mm, and a corner radius of 14.5 mm to produce a molding material of Example 2.

<Example 3>
Si: 0.4% by mass or less, Mg: 2.1-2.9% by mass, Fe: 0.5% by mass or less, Cu: 1.2-2.0% by mass, Mn: 0.3% by mass or less , Cr: 0.18 to 0.28 mass%, Zn: 5.1 to 6.1 mass%, the aluminum alloy ingot consisting of the balance Al and inevitable impurities, the same process and conditions as in Example 2 Was rolled to obtain an aluminum alloy rolled sheet having a thickness of 1.5 mm and a 0.2% proof stress of 550 MPa and a breaking elongation of 9%.
When the cross section of the plate was observed with an optical microscope and a deflecting lens, a fibrous crystal structure extending in a direction perpendicular to the thickness direction was observed.
And the nylon resin film of thickness 90micrometer was laminated | stacked through the adhesive layer which consists of an acrylic adhesive as a coating | covering material on the lower surface of the aluminum alloy rolling board which comprises the outer surface of a small electronic device case.
The aluminum alloy rolled laminated sheet material thus obtained was cut into a substantially rectangular shape with a length of 150 mm, a width of 82 mm, and a corner radius of 14.5 mm, thereby producing a molding material of Example 3.

<Example 4>
The same aluminum alloy rolled sheet material as in Example 1 was prepared.
And the nylon resin film of thickness 90micrometer was laminated | stacked through the adhesive layer which consists of an acrylic adhesive as a coating | covering material on the lower surface of the aluminum alloy rolling board which comprises the outer surface of a small electronic device case.
The aluminum alloy rolled laminated sheet material thus obtained was cut into a substantially rectangular shape having a length of 150 mm, a width of 82 mm, and a corner radius of 14.5 mm to produce a molding material of Example 4.

<Comparative Example 1>
Si: 0.4 mass% or less, Mn: 0.4-1.0 mass%, Mg: 4.0-4.9 mass%, Fe: 0.4 mass% or less, Cr: 0.05-0. Extruded aluminum alloy with a thickness of 2 mm, containing 25% by mass, Zn: 0.25% by mass or less, consisting of an aluminum alloy consisting of the balance Al and inevitable impurities, 0.2% proof stress 230 MPa, and breaking elongation 14% Board material was prepared. The plate material is extruded and does not have a fibrous crystal structure extending in a direction orthogonal to the thickness direction.
And the nylon resin film of thickness 90micrometer was laminated | stacked through the adhesive layer which consists of an acrylic adhesive as a coating | covering material on the upper and lower surfaces of the aluminum alloy extrusion board material, respectively.
The aluminum alloy extruded laminate obtained in this way was cut into a substantially rectangular shape having a length of 150 mm, a width of 82 mm, and a corner radius of 14.5 mm, thereby producing a molding material of Comparative Example 1.

<Comparative example 2>
Si: 0.4% by mass or less, Mg: 2.1-2.9% by mass, Fe: 0.5% by mass or less, Cu: 1.2-2.0% by mass, Mn: 0.3% by mass or less , Cr: 0.18 to 0.28 mass%, Zn: 5.1 to 6.1 mass%, consisting of an aluminum alloy consisting of the balance Al and inevitable impurities, 0.2% proof stress of 510 MPa, elongation at break An aluminum alloy extruded plate material having a thickness of 1.5 mm and 11% was prepared. The plate material is extruded and does not have a fibrous crystal structure extending in a direction orthogonal to the thickness direction.
The aluminum alloy extruded plate was cut into a substantially rectangular shape having a length of 150 mm, a width of 82 mm, and a corner radius of 14.5 mm, thereby producing a molding material of Comparative Example 2.

<Comparative Example 3>
Si: 0.2-0.6 mass%, Mg: 0.45-0.9 mass%, Fe: 0.35 mass% or less, Cr: 0.1 mass% or less, Zn: 0.1 mass% or less The aluminum alloy casting soul containing the balance Al and inevitable impurities was homogenized at 580 ° C. for 10 hours, then face-cut, preheated at 500 ° C., and hot rolling was started. The final pass start temperature of hot rolling was 400 ° C., and after the pass, cooling was performed at a rate of 80 ° C./min. Thereafter, heat treatment was performed at 240 ° C. for 4 hours. Then, after cold rolling at a reduction rate of 57%, heat treatment was performed at 250 ° C. for 2 hours. Thus, a rolled aluminum alloy sheet having a thickness of 3 mm and a 0.2% proof stress of 150 MPa and a breaking elongation of 14% was obtained. The plate material has been subjected to natural aging treatment after cold rolling, and does not have a fibrous crystal structure extending in a direction perpendicular to the thickness direction.
And the nylon resin film of thickness 30 micrometers was laminated | stacked as the coating | covering material through the adhesive layer which consists of an acrylic adhesive on both the upper and lower surfaces of an aluminum alloy rolled sheet material, respectively.
The aluminum alloy rolled laminated sheet material thus obtained was cut into a substantially rectangular shape having a length of 150 mm, a width of 82 mm, and a corner radius of 14.5 mm to produce a molding material of Comparative Example 3.

<Comparative example 4>
Si: 0.2-0.6 mass%, Mg: 0.45-0.9 mass%, Fe: 0.35 mass% or less, Cr: 0.1 mass% or less, Zn: 0.1 mass% or less An aluminum alloy rolled sheet material having a thickness of 2 mm, which is made of an aluminum alloy containing the balance Al and inevitable impurities, having a 0.2% proof stress of 145 MPa and a breaking elongation of 12%, was prepared. The plate material is obtained by cold rolling (33% reduction) of the extruded plate material, and does not have a fibrous crystal structure extending in a direction orthogonal to the thickness direction.
And the nylon resin film of thickness 30 micrometers was laminated | stacked as the coating | covering material through the adhesive layer which consists of an acrylic adhesive on both the upper and lower surfaces of an aluminum alloy rolled sheet material, respectively.
The aluminum alloy rolled laminated sheet material thus obtained was cut into a substantially rectangular shape having a length of 150 mm, a width of 82 mm, and a corner radius of 14.5 mm, thereby producing a molding material of Comparative Example 4.

<Molding of small electronic equipment case>
By drawing the molding materials of Examples 1 to 4 and Comparative Examples 1 to 4 using the drawing apparatus shown in FIG. 2, the length is 140.5 mm, the width is 70.5 mm, and the side wall height (molding height). A small electronic device case having a size of 7 mm and a side wall corner portion of 2 mm was molded. The angle of the side wall with respect to the bottom wall was 90 °.
As a result of visual observation of each molded case, no wrinkles or cracks occurred in the corner portions of the side walls of the molding materials of Examples 1 to 4, and the lower mold was formed on the outer surface of the side walls. There were no scratches due to contact.
On the other hand, about the case which consists of a molding material of Comparative Examples 1-4, the wrinkles and the crack had arisen in the corner part of the side wall. Further, in the case of the case made of the molding material of Comparative Examples 1, 3, and 4, no scratch was found on the outer surface of the side wall, but the outer surface of the side wall of the case made of Comparative Example 2 was damaged by contact with the lower mold. Was formed.

  The present invention can be suitably used for forming a case of a small electronic device such as a tablet terminal, a mobile communication terminal device, a notebook computer, a mobile phone, a portable music device, a digital camera or the like.

(1): Aluminum alloy rolled laminate
(2): Aluminum alloy rolled sheet
(3) (4): Coating material
(30) (40): Synthetic resin film
(31) (41): Metal foil
(32) (33) (42) (43): Synthetic resin film
(5): Fixed female type
(6): Movable male type
(20): Small electronic equipment case
(21): Bottom wall
(22): Side wall
(22a): Corner part (side wall)

Claims (11)

  An aluminum alloy rolled laminated sheet material for forming a small electronic device case by drawing, wherein the 0.2% proof stress is 200 MPa or more, and at least one of both surfaces of the aluminum alloy rolled sheet material A small electronic device comprising a synthetic resin film and a laminate in which a synthetic resin film is laminated on both surfaces of a metal foil. Aluminum alloy rolled laminated sheet material for cases.   The aluminum alloy rolled laminated sheet material for a small electronic device case according to claim 1, wherein the aluminum alloy rolled sheet material has a fibrous crystal structure extending in a direction orthogonal to the thickness direction.   An aluminum alloy rolled sheet material contains Mn: 0.2 to 0.7% by mass, Mg: 2.0 to 5.0% by mass, and an Al—Mn—Mg based alloy composed of the balance Al and inevitable impurities, Si: Al-Si-Mg-based alloy containing 0.2 to 0.8 mass%, Mg: 0.4 to 1.2 mass%, the balance being Al and inevitable impurities, and Zn: 4.0 to 6.5 The mass%, Mg: 0.5-3.0 mass%, consisting of any one aluminum alloy of the Al-Zn-Mg based alloy consisting of the balance Al and inevitable impurities. Aluminum alloy rolled laminate for small electronic equipment cases.   The aluminum alloy rolled laminated sheet material for a small electronic device case according to any one of claims 1 to 3, wherein the thickness of the covering material is 0.05 to 1.5 times the thickness of the aluminum alloy rolled sheet material.   The aluminum alloy rolled laminated sheet material for a small electronic device case according to any one of claims 1 to 4, wherein the aluminum alloy rolled sheet material has a thickness of 0.5 to 3.5 mm.   The covering material which consists of a 50-100-micrometer-thick polyester resin film or a polyamide resin film is laminated | stacked on the surface used as the outer surface of a small electronic device case among both surfaces of an aluminum alloy rolled sheet material. The aluminum alloy rolled laminated sheet material for a small electronic device case according to one.   The covering material which consists of a 10-100-micrometer-thick polyethylene resin film, a polypropylene resin film, or a polyamide resin film is laminated | stacked on the surface used as the inner surface of a small electronic device case among both surfaces of an aluminum alloy rolled sheet material. The aluminum alloy rolled laminated sheet material for a small electronic device case according to any one of 6.   The aluminum alloy rolled laminated sheet material for small electronic device cases according to any one of claims 1 to 7, wherein at least one of the inner and outer surfaces is made of a synthetic resin film or a laminate. A small electronic device case with a covering, covered with a material.   After the aluminum alloy rolled laminated sheet for small electronic equipment case according to any one of claims 1 to 7 is drawn, the covering material covering at least one of the inner and outer surfaces is removed. Small electronic equipment case.   The bottom wall and a side wall rising from the periphery of the bottom wall, the height of the side wall is 0.5 to 25 mm, and the angle of the side wall to the bottom wall is 90 to 150 °. Small electronic device case.   A method for forming a small electronic device case, comprising drawing the aluminum alloy rolled laminated sheet material for a small electronic device case according to any one of claims 1 to 7.