JP2001170734A - Magnesium alloy thin formed body and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnesium alloy thin formed body of a light weight, of high quality and having a small radius of a corner part and a boss part by forging. SOLUTION: A magnesium alloy thin formed body, which is formed by forging a magnesium alloy sheet stock, has an essential part thickness of <=1.5 mm, a rising inside corner part of a wall part and/or a chamfer/radius of an outside corner part of <=1 mm, a height of a wall part of <=30 mm and a boss part of a principal part thickness of ten times or less. A manufacturing method of the magnesium alloy thin formed body is constituted so that a magnesium alloy sheet stock of a sheet thickness of <=3 mm, with using the die having a chamfer/radius of a rising inside corner part of a wall part and/or an outside corner part of <=1 mm and having a recessed part in a punch or a die, is subjected to rough forging under a stock temperature of 200-540 deg.C, a forming load of 1-30 ton/cm2, a forging speed of 1-500 mm/sec, a draft of <=75% and then is subjected finish forging at a draft <=30%, an essential part thickness is made <=1.5 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact formed by forging a thin sheet made of a magnesium alloy and a method for producing the same. Particularly, a thin compact made of a magnesium alloy suitable for use as a housing of a small and lightweight device. And a method of manufacturing the same.

[0002]

2. Description of the Related Art Magnesium is the material having the lowest specific gravity among the metal materials currently put into practical use. That is, the specific gravity of magnesium is 1.8, which is much smaller than the specific gravity of aluminum, which is currently widely used in various applications as a lightweight material, of 2.7. For this reason,
Magnesium alloys are recently attracting attention as lightweight materials that replace aluminum alloys, and are used for aviation and space equipment parts, land transportation equipment, cargo handling equipment, industrial machinery and tools, electrical and communication equipment, agricultural and forestry mining machinery, office equipment, and optical equipment. It is being used in a wide range of fields such as equipment and sports equipment.

However, compared to aluminum alloys,
Magnesium alloys have a problem in plastic workability. For this reason, at present, most magnesium alloys are used as cast materials. In general, a magnesium alloy used as a casting material achieves castability while improving strength by adding aluminum and zinc as basic additive elements to magnesium as a main component element. Further, zirconium may be added to impart strength and toughness, Mn may be added to reduce the size of crystal grains, or a rare earth element or silver may be added to impart heat resistance. . However, the compact obtained by casting the magnesium alloy melt is limited to a relatively thick one due to restrictions on the manufacturing method. Further, during the manufacturing process, there is a great possibility that casting defects and oxides are interposed inside and on the surface. If these defects are present, there is a problem in mechanical strength, and a problem also occurs in corrosion resistance and the like.

[0004] As a possibility of solving the above-mentioned problems in a magnesium alloy casting, a semi-solid molding method in which injection molding is applied and molding is performed in a solid-liquid coexisting region has been proposed and studied. I have. The molded body obtained by this molding method has no dendrite as seen in general castings, has a fine structure, and has a smaller number of pores and a higher density than the molded body obtained by the die casting method. There is an advantage that heat treatment after molding is possible. According to this method, the thickness of the molded body can be reduced to some extent, and a molded body having a thickness of 1.5 mm or less is also manufactured. However, even in the case of the magnesium alloy molded body by this semi-solid molding method, since there is no possibility that casting defects or oxides are interposed inside and on the surface during the production process,
There is a problem that it is difficult to mass-produce high quality products industrially.

As one method of obtaining a thin molded body made of a magnesium alloy, drawing from a magnesium alloy sheet material is considered. That is, first, an ingot is produced by a casting method, and the ingot is forged to remove or reduce internal defects, segregation, and the like, which are problems of the cast product. Next, this forged product is cut or rolled to an appropriate thickness to prepare a thin plate material, and the thin plate material is drawn to form a formed body. References that disclose the drawing of magnesium alloy sheets include, for example, JP-A-6-55230 and JP-A-6-55230.
No. 328155, and the summary of the lecture of the 89th Autumn Meeting of the Japan Light Alloy Society in 1995, pages 179 to 180.

[0006] The radius of the shoulder of the die and punch in the draw forming process of the magnesium alloy is determined by the blank material (material).
It is said that it should be designed to be 15 to 5 times and 5 times or more the plate thickness ("Press Handbook" published by Maruzen, 1983, 63
See page 3.) For this reason, in the above “Summary of the 89th Autumn Meeting of the Light Alloy Society of Japan”, an AZ31 magnesium alloy disk having a diameter of 60 to 65 mm and a thickness of 1 mm is also used for punch diameter 4 mm.
0mm, punch shoulder radius 12mm, die inner diameter 43mm,
It is disclosed that a deep drawing test was performed under the conditions of a die shoulder radius of 8 mm and a blank pressure of 1000 kgf. That is,
In the drawing process, if the die shoulder radius is designed to be smaller than the above range, there is a possibility that a crack may occur in the formed body, and therefore, there is a problem that it is difficult to produce a formed body having a sharp shape. Also, since it is difficult to form a thick boss integrally with the molded body in the draw forming process,
Bosses and the like are secured where necessary by welding different materials. In addition, in the above-mentioned JP-A-6-55230,
"The surface temperature of both the punch and the flange is 175 ° C or more, 5
Molding using a mold heated to a temperature range of not more than 00 ° C. enables deep drawing of a magnesium thin plate, '' which suggests that a heating temperature suitable for warm working is suggested. There is no disclosure or suggestion about the shape of the punch or the flange.

[0007]

In recent years, electronic circuit components and
With high integration and high density of devices, miniaturization and weight reduction of small communication equipment such as mobile phones, small office equipment such as notebook and mobile personal computers, and many other applications are actively pursued. Therefore, miniaturization and weight reduction of housings of these devices are also required. To meet such demands, thin-walled compacts made of aluminum alloys are widely used, but in order to further reduce the weight while maintaining the same or higher mechanical strength, thin-walled compacts made of magnesium alloy The emergence of is desired. In addition, such a small component housing requires a boss portion for connecting the housing components to each other, or for locking or fixing a built-in electronic circuit board or the like. However, since magnesium has a dense hexagonal crystal structure, plastic working of a magnesium alloy is extremely difficult. For this reason, the plastic working technology of a magnesium alloy thin plate is hardly studied at home and abroad, and its mechanical properties and workability are not well known.

[0008] In the above-described drawing from a magnesium alloy thin plate material, it is essential to prevent the generation of wrinkles, and there is a problem in terms of material yield because a wrinkle holding portion is required. This is a serious problem particularly when a small molded product is manufactured. In addition, a defect such as a crack is likely to be generated in a fillet portion corresponding to a corner portion and a shoulder portion of the die and the punch, so that there is a problem that the radius of the die corner portion and the punch shoulder portion cannot be reduced too much. Also, in the case of drawing, unlike the casting method, there is a fundamental problem that a partially thick boss portion or a step portion formed integrally cannot be formed.

The present invention has been made to solve the problems in the prior art, and is made of a magnesium alloy that is lighter than an aluminum alloy, and has a main portion having a thickness of 1.5 mm or less, or a peripheral wall portion. Another object of the present invention is to provide a magnesium alloy thin molded body in which one or more bosses thicker than the main part thickness are integrally formed at any necessary place.

[0010]

Means for Solving the Problems The present inventors have studied various processing methods in order to achieve the above object, and as a result, forging a thin plate made of a magnesium alloy to obtain a desired thin wall. The inventors have found that a molded body made of a magnesium alloy can be produced, and have completed the present invention. That is, the above-mentioned object has been achieved by a novel means different from casting and drawing methods in which a thin sheet material made of a magnesium alloy is stretched by forging to obtain a formed body.

That is, the magnesium alloy thin molded body of the present invention is characterized in that a magnesium alloy thin plate material is formed by forging. The main part of the thin molded body has a thickness of 1.5 mm or less. Here, the thickness of the main portion refers to a substantially uniform thickness portion such as the bottom portion 22 and the peripheral wall portion 23 occupying most of the molded body shown in FIG. The thickness of the protruding part is not taken into account. If the thickness of the main part exceeds 1.5 mm, it may not be possible to secure an internal volume to be mounted in the molded body when the external dimensions of the molded body are constant. In order to secure the rigidity of the molded body, the thickness of the main part is set to 0.2 mm or more. Preferably, the main part thickness is 0.3 to 0.8 mm.

The magnesium alloy thin-walled molded article of the present invention may further have a peripheral wall portion, wherein the rising inner corner portion and / or the outer corner portion of the peripheral wall portion have a chamfer or radius of 1 mm or less. Is not more than 30 mm in height. By providing the peripheral wall portion, the peripheral wall portion and another component can be combined to form a box-shaped housing. In addition, when the chamfer or the radius of the rising inner corner portion and / or the outer corner portion of the peripheral wall portion is 1 mm or less, preferably 0.5 mm or less, when used as a housing, compared with a large radius. This has the advantage that the internal volume is large. This difference is extremely important especially when the shape and dimensions of the housing are small, and is significant in mounting electronic circuits.
Further, since a housing having a sharp appearance can be manufactured, an industrial product excellent in design can be provided. If the height of the peripheral wall is 30 mm or less, it can be used, for example, as a housing for electronic equipment. In addition, it is possible to forge a thin sheet made of a magnesium alloy to this height.
Here, the peripheral wall portion refers to an L shape having a rising portion on one side, a U shape having both rising portions, or a box-like wall-shaped rising portion.

Further, the magnesium alloy thin molded body of the present invention is characterized in that it has one or more bosses thicker than the main part. The boss is not more than 10 times the thickness of the main part of the thin molded body. The boss part,
For example, there is an advantage that a screw hole for attachment can be formed in the boss. Further, in a thin-walled molded body formed by drawing or the like, a portion such as a boss portion in the present invention is separately formed,
Parts are made by welding or adhesives.
There are many manufacturing steps and there is a problem in reliability. Since the molded body of the present invention has the boss portion formed integrally,
There is no such problem at all.

The thin-walled product made of a magnesium alloy of the present invention is characterized in that the surface thereof has a convex portion made of at least one of a numeral, a symbol, a mark, and a pattern. And this convex part is characterized in that the back surface is not concave. By forming the convex portion, it is not necessary to attach another component again. In addition, the magnesium alloy thin molded body of the present invention is characterized in that a thin part of 0.3 to 0.8 mm is intermittently and / or continuously unevenly distributed. A label or the like can be attached to the thin portion. The magnesium alloy thin molded product of the present invention is for electronic devices, and is particularly suitable for mobile phones, mobile personal computers, or notebook personal computers.

The magnesium alloy thin molded article of the present invention is a forged molded article, which is different from a molded article produced by a casting method, for example, has a fine average crystal grain size of about 10 to 300 μm and has excellent mechanical strength. It has a clear difference in its structure, mechanical strength, etc. Further, the thin sheet material used for the molded body has an elongation of about 25%, which is smaller than that of the material after forging, but still has an elongation of 10 to 15%.

Next, the manufacturing method of the magnesium alloy thin molded body of the present invention is as follows: a magnesium alloy thin plate material having a thickness of 3 mm or less is formed by forming a 1-30 ton / cm ² molding load, 1-500 mm / sec forging speed, and rolling down. After rough forging at a rate of 75% or less, finish forging at a reduction rate of 50% or less.
It is characterized by being 5 mm or less.

In the above-mentioned method for producing a magnesium alloy thin molded body, the magnesium alloy thin plate material is 3 m
m, the rolling reduction in forging must be increased in order to obtain the target thin-walled molded body of 1.5 mm or less, and the metal flow of the magnesium alloy during forging (hereinafter, referred to as
This is because reflowed fine particles may appear along the metal flow or may be segregated. In order to prevent this, it is necessary to precisely control various conditions such as a molding load, a forging temperature, a mold temperature, a forging speed, and a reduction ratio. It is preferable to use a rolled material as the thin sheet material to be used in consideration of the uniformity of the structure, defects, and the like.

If the molding load is less than 1 ton / cm ^2, it is difficult to mold, so the lower limit is 1 ton / cm ² . On the other hand, if the molding load exceeds 30 ton / cm ² , the load on the product and the mold becomes excessive, so the upper limit is set to 30 ton / cm ² . In particular, 3 to 30 ton / cm ² for rough forging that requires a forming load, and 1 to 20 ton for finish forging where a small forming load is sufficient.
On / cm ² is preferred.

When the forging speed is less than 1 mm / sec, the temperature of the thin plate material is lowered, and it is difficult to obtain a material having good forging accuracy.
In addition, since the productivity is reduced, the lower limit is set to 1 mm / sec. On the other hand, when the forging speed is a high speed exceeding 500 mm / sec, the metal flow cannot smoothly follow the forging speed, and the metal flow is disturbed and a desired shape cannot be obtained. 500 mm / sec. The forging speed is preferably from 10 to 500 mm / sec for rough forging with emphasis on productivity and from 1 to 200 mm / sec for finish forging with emphasis on formability.

The rolling reduction in rough forging is limited to 75% or less because a large forming load is required in accordance with the rolling reduction, and the sheet material is stretched at a rolling reduction of 75% or less. This is because a rough forged product having a bottomed shape having a peripheral wall portion and a boss portion can be formed. On the other hand, when the rolling reduction exceeds 75%, the magnesium alloy sheet itself generates heat during forging and the temperature rises, and depending on the preheating condition, there is a risk of ignition and combustion. Therefore, considering safety,
More preferably, the rolling reduction during rough forging is 50% or less. The reason why the reduction ratio in the finish forging is set to 50% or less is that the dimensions of each part having a relatively rough tolerance of the rough forged molded body are
This is performed for the purpose of, for example, precisely finishing the target to the shape and size of the formed body, and the formability is more important than the processing amount. Considering the surface properties and the like of the finished molded product, the content is preferably 30% or less. Here, the rolling reduction refers to the reduction in wall thickness due to one reduction in the same forging, and does not refer to the total reduction in wall thickness due to multiple reductions in the same process.

Further, in the method for producing a thin magnesium alloy body according to the present invention, the temperature of the magnesium alloy sheet material is 200 to 540 ° C. and the punch shoulder radius (“r1”) of the rough forging die. ) Or die corner radius ("r
2 ") and the radius of the punch shoulder of the finish forging die (referred to as" r3 ") or the radius of the die corner (referred to as" r4 "), r1 (or r2) / r3 (or r4). )
Forging is performed using a mold having a diameter of 7 or less, and the chamfer or radius of the rising inner corner and / or the outer corner of the peripheral wall of the finished molded body is 1 mm or less.
If the temperature of the magnesium alloy thin plate material or the rough forged molded body is less than 200 ° C., the metal flow during forging cannot be obtained smoothly, and the boss formed in the space of the mold composed of the punch and the die, particularly in the corners Since the portion is filled with the magnesium alloy and does not spread, it is difficult to reduce the thickness and it is not possible to form a good peripheral wall portion or a boss portion. On the other hand, when the temperature of the magnesium alloy thin plate material or the roughly forged compact is 5
If the temperature exceeds 40 ° C., the crystal grains become coarse and the crystal grain size becomes 3
If it exceeds 00 μm, elongation is lost. Also, depending on the processing rate, there is a risk of ignition and burning.
Is the upper limit temperature. Preferably, the temperature is 450 ° C. or lower.
Punch shoulder radius of the rough forging die (referred to as “r1”)
Or the ratio of the die corner radius (referred to as “r2”) to the punch shoulder radius (referred to as “r3”) or the die corner radius (referred to as “r4”) of the finish forging die, r1 ( Or r
2) When / r3 (or r4) is 7 or more, it becomes difficult to form a corner having a desired radius by finish forging. When the corner radius of the target finished forged product is a small radius of less than 1 mm, the above ratio, r1 (or r1)
2) It is preferable that / r3 (or r4) be 2 or more. In the case of 2 or less, the radius of the punch shoulder of the rough forging die is too small, and there is a possibility that the action of drawing at the initial stage of processing in rough forging and the metal flow during forging may not be performed well. is there. In addition, the shoulder radius of the convex portion formed on either the upper die or the lower die in the finish forging die, and formed on the other of the lower die or the upper die corresponding to the convex portion. The radius of the rising corner of the concave portion is preferably substantially the same for the same reason as in the case of the rough forging die.

The radius of the tip shoulder of the punch portion (convex portion) formed on either the upper die or the lower die in the rough forging die is not instantaneous at the initial stage of forging, but is reduced. It is preferable that the diameter is as large as possible in order to make the function close to the processing, and it is preferable that the diameter be 1 mm or more. Even if the radius of the tip shoulder is less than 1 mm, molding is not impossible, but it is difficult to produce a thin-walled molded body whose effective height of the peripheral wall portion exceeds tens of mm particularly due to the metal flow at the corners and the like. In order to make the radius of the inner corner portion and / or the outer corner portion of the completed molded body 0.5 mm or less, the radius of the tip shoulder is preferably 1 mm to 5 mm. The shoulder radius of the convex portion formed on the other of the lower die and the upper die and the radius of the rising corner of the concave portion facing the convex portion are smaller than those of the other portions. It is preferable that the thicknesses be substantially the same so that the thickness of the sheet does not change much. Further, in the present invention, when the corner radius of the target finish forged product is 0.5 mm or less and the lower mold of the outer corner is an integral type, stress concentration occurs at the corner and the corner of the mold is formed. There is a possibility that a crack may occur in the portion and the life of the lower mold may be shortened. In order to prevent this, a part of the lower mold is used as a telescopic mold. By doing so, the function of an air vent is also achieved, and stress concentration is not applied to the corners, so that the life of the mold is prolonged, and a sharp corner is obtained in the molded article.

Alternatively, the method of manufacturing a thin-walled product made of a magnesium alloy according to the present invention is characterized in that a forged product having a boss portion is forged by using a die having at least one recessed portion in a punch or a die. Rough forging to be formed, and forging the rough forged molded body into a punch or a die using a mold having a recessed portion corresponding to the boss portion, to have a boss height of 10 times or less with respect to the thickness of the main portion. It is characterized by the following.

In the rough forging die, at least one of the upper and / or lower molds, for example, at the necessary place of the punch part (convex part) or the die part (concave part),
A dent corresponding to the boss of the target molded body is formed.
In order to obtain a good boss with a thin-walled molded product, the depth of the dent corresponding to the boss should be 7 times or less the thickness of the main part of the completed thin-walled molded product due to metal flow in rough forging. In the forging, it is preferable to suppress it to 10 times or less, preferably 7 times or less.

Alternatively, the magnesium alloy thin sheet material has a thickness of 3 mm or less, and the rough forging die has a thickness of 1 mm or less.
The finish forging die is heated to 100 to 540 ° C., and the finish forging die is heated to 100 to 540 ° C.

As the magnesium alloy thin plate material, a material prepared to have a size almost equivalent to the surface area of the target thin-walled molded body is used. If the thin sheet material is too large, defects such as wrinkles may occur in the peripheral wall and corners of the formed body during rough forging. On the other hand, if it is too small, a good metal flow cannot be obtained at the corners, so that a peripheral wall of a predetermined height is not formed, cracks or chips are generated at the rising corners and corners of the peripheral wall, A problem such as chipping of the boss portion occurs, and a high quality thin-walled molded product cannot be formed.

In the present invention, the above-mentioned forging basically comprises a two-stage forging process of rough forging and finish forging. However, a thin molded body having a more accurate shape and excellent surface properties is obtained. For this purpose, one or more intermediate forgings may be further included. In the present invention, the preheating of the thin sheet material is an essential condition, because it is not possible to perform heating by conduction heat from a mold because it does not hold down wrinkles like drawing. Further, in the case of conduction heat, the temperature of the thin plate material may become unstable. When the preheating of the thin sheet material or the rough forged molded body is performed in the air, the surface is oxidized, which may adversely affect forgeability, corrosion resistance, appearance, and the like. For this reason, it is preferable to carry out in an inert gas atmosphere such as argon gas. In addition, an electric heating furnace whose atmosphere can be easily controlled is usually preferably used for preheating.

In the present invention, the finish forging is performed to finish the formed body to the final shape and dimensions, but it is necessary to form a groove of a predetermined shape or a step portion on the bottom surface of the die portion of the finish forging die. Accordingly, a mark such as a mark is integrally formed on the outer surface of the molded body at the time of finish forging, and the corresponding back surface is flat and need not be concave, or a step can be formed. The thickness of the main part is 1.5 mm or less. At this time, the step portion or the gradual change in the thickness can be unevenly distributed or continuous.
It is also possible to make it 8 mm.

A molded article obtained by the production method of the present invention having a small corner radius of 1 mm or less, preferably 0.5 mm or less, has a smaller content than that of a large radius when used as a housing. The advantage is that the product is large. This difference is extremely important especially when the shape and dimensions of the housing are small, and is significant in mounting electronic circuits. Further, since a housing having a sharp appearance can be manufactured, an industrial product excellent in design can be provided. Further, according to the production method of the present invention, a forged thin-walled product made of a magnesium alloy having a main portion having a thickness of 1.5 mm or less and having a boss portion integrally at a corner, a corner, or any necessary portion can be realized. The thin-walled molded body having such a configuration has an advantage that, for example, a screw hole for attachment or a receiver for an electronic circuit board can be formed in the boss portion. Further, in a thin-walled molded body formed by drawing or the like, parts such as the boss portion in the present invention are separately formed and fixed by welding, an adhesive, or the like to produce a part. There is also a problem in terms of reliability. The molded article obtained by the production method of the present invention has no such problem because the boss is formed integrally. Further, it is preferable that the thin-walled molded product according to the present invention is subjected to temporary corrosion protection, painting, and anodizing film treatment after performing desired trimming and machining. That is, the magnesium alloy may be oxidized even after forging, and the surface may lose its metallic luster. However, the thin-walled molded article of the present invention is excellent in the roughness of the outer surface, and the outer surface of the bottom portion and / or the side peripheral wall portion. By applying an anodic oxide film treatment to the metal substrate, it is possible to realize a glossy molded body of the metal substrate itself. The present invention can be applied to a mobile phone housing, a mobile personal computer housing, a notebook personal computer housing, and the like.

Forging a magnesium alloy sheet material,
When manufacturing a thin-walled molded body, it is preferable that the magnesium alloy be excellent in forgeability. For this reason, in the present invention, Al: 1 to 6%, Mn: 0.
It is preferable to select a magnesium alloy material containing 5% or less, a trace element 0.2% or less, the balance being Mg and unavoidable impurities, or a magnesium alloy material further containing Zn: 2% or less in the above composition. If aluminum is low, forgeability is good, but rigidity deteriorates. Therefore, it is preferable that aluminum is at least 1% or more. On the other hand, if the aluminum content increases, the forgeability and corrosion resistance decrease, so the aluminum content is preferably 6% or less. Zinc has the same effect, and is preferably 2% or less in view of the balance between forgeability and surrounding property (metal flow). As such an alloy, for example, AZ31 alloy of ASTM standard,
There are AZ21 alloy, AM20 alloy and the like. The magnesium alloy that can be applied to the present invention is not limited to the above composition, and a magnesium alloy to which a rare earth element, lithium, zirconium, or the like is added as a trace element can also be applied to the present invention.

[0031]

Embodiments of the present invention will be described below. (Embodiment 1) FIG. 2 is a schematic structural perspective view for explaining one example of a magnesium alloy thin molded body to be produced according to the present invention. In FIG. 2, reference numeral 21 denotes a thin formed body made of a magnesium alloy.
The cross section having the bottom portion 22 and the peripheral wall portion 23 is a substantially concave molded body. Further, the thickness t of the bottom portion 22 and the peripheral wall portion 23 is extremely thin as 1.5 mm or less, and the inner corner 24 or the corner 25 of the portion where the peripheral wall portion 23 rises from the bottom portion 22 is thicker than the main portion thickness. Also, a thick boss portion 26 is formed. In FIG. 2, the boss 26 is formed at the corner 25, but the present invention is not limited to this, and the boss 26 may be formed at an appropriate position on the corner 24. Alternatively, it may be formed at the bottom center portion. Further, in FIG. 2, the bottom portion 22 has a flat shape, but a step portion having an arbitrary shape may be formed.

FIG. 1 is a schematic structural explanatory view showing an example of a rough forging die in a forging machine for carrying out the manufacturing method of the present invention. In FIG. 1, reference numeral 11 denotes a magnesium alloy thin plate material, and a concave portion (hereinafter referred to as
(Also referred to as a “die part”) 13. In FIG. 1, a thin plate material having a shape slightly larger than the concave portion size is used. However, since the mounting position changes according to the shape and size of the thin plate material to be used, for example, a slight gap is formed between the thin plate material and the bottom surface. It may be placed to have. The thickness and the size of the thin sheet material 11 to be used are determined by appropriate forging conditions such as the target thickness of the molded body, the height of the peripheral wall, the shape of the boss to be produced, the mold temperature and the draft. Choose a thickness and size. In the present invention, the plate thickness is 1.5
mm magnesium alloy sheet material is used,
Usually, it is preferable to use a thin plate material whose size is equal to or slightly larger than the surface area of the molded product to be obtained. Reference numeral 14 denotes an upper die, which has a convex portion (hereinafter also referred to as a “punch portion”) 15 corresponding to the concave portion 13 of the lower die 12. Reference numeral 16 denotes heaters for heating the upper and lower molds, respectively, and a plurality of heaters are installed to heat the die and punch portions of the upper and lower molds to a uniform temperature. Reference numeral 17 denotes a thermocouple for measuring the temperature of the upper and lower molds, which is usually installed near the die section and the punch section, and refers to the detection output thereof to control the upper and lower molds by heating temperature control means (not shown). The mold is heated and held at a predetermined temperature. Reference numeral 18 denotes a dent provided on the shoulder of the punch corresponding to the boss to be formed. Due to the presence of the dent, a rough forged product having the boss is formed during rough forging.

In the present invention, the lower mold 1 to be subjected to rough forging
Corner radius r2 (not shown) of the second die portion (recess) 13
The shoulder radius r1 (not shown) of the punch portion (convex portion) 15 of the upper mold 14 is formed as a curved surface as large as possible. As a result, the behavior close to drawing at the initial stage of rough forging is performed smoothly, and it is possible to secure a good metal flow at the time of forging, and the metal flow enters the mold gap without cracking or chipping etc. It is stretched while being filled. However, in finish forging, the corner was 1m
When processing to a small radius of less than m, if the corner radius and shoulder radius are too large, cracks will be generated at the corners and the like at the time of finish processing. In such a case, five times the thickness of the thin sheet material It is preferable to set the following.

In the present invention, the radius r1 of the shoulder portion (not shown) or the radius r2 of the die portion (not shown) in the rough forging die, and the radius r3 of the shoulder portion in the finish forging die.
(Not shown) or the radius of the die part r4 (not shown), the former (r1 or r2) is the latter (r3 or r3).
It is preferable to set the range to 7 times or less of 4). When the ratio exceeds 7, when finishing forging from a rough forged molded body, defects such as cracks are generated at corners, and it becomes difficult to obtain a thin molded body having good properties. It is. In addition, when the radius of the corner of the finish forged body is a small radius of 1 mm or less, the radius of the corner in the rough forging die is too small, and there is a possibility that defects such as cracks may occur in the corner during rough forging. Therefore, the ratio is preferably set to 2 or more.

In the present invention, a depression corresponding to a mark or the like or a step corresponding to a portion to be machined in a later step is formed on the bottom surface of the concave portion of the lower die for finish forging in advance. During the finish forging, part of the metal flow of the rough forged molded body fills and expands into the dents and steps, so the volume of the volume, such as numbers, symbols, marks, patterns, marks, etc. It is also possible to make small engravings, and if necessary, to form a step on the bottom surface. Although the type of forging machine for carrying out the present invention is not particularly limited, a mechanical forging machine having a high forging speed is used for rough forging, and a forging speed is used for finish forging for forming the final product dimensions. It is preferred to use a relatively slow hydraulic forging machine. In addition, the thin formed body made of the magnesium alloy obtained by the above forging usually has forging burrs at the upper end portion of the peripheral wall or the like, so it is necessary to perform trimming for removing the forging burrs. Also, if necessary, a desired portion is appropriately machined. Magnesium alloys may be oxidized even after forging and lose their metallic luster. Thus, for example,
By forming an oxide film by anodic oxide film treatment, it is preferable to obtain a thin-walled product made of a magnesium alloy having excellent anticorrosion properties and a metallic luster utilizing an alloy base that cannot be obtained by ordinary coating. The magnesium alloy thin molded body of the first embodiment is suitable for use as a thin casing for reducing the weight of various devices, and is used for a mobile phone casing, a mobile personal computer casing, and a notebook personal computer. It can be wide, such as a housing.

(Embodiment 2) FIG. 5 is a schematic structural perspective view for explaining one example of a magnesium alloy thin formed body to be manufactured according to the present invention. In FIG.
Reference numeral 31 denotes a thin formed body made of a magnesium alloy, which is a basically shaped body having a bottom 32 and a peripheral wall 33 and a substantially concave cross section. Further, the bottom portion 32 and the peripheral wall portion 33
Has a very thin wall thickness of 1.5 mm or less, and
Inner corner 3 of the portion where the peripheral wall 33 rises from the bottom 32
4 or the outer corner 38 at the bottom of the peripheral wall has a radius of 0.5 m.
m, and the bosses 35, 35 ', which are thicker than the main part,
36 and 37 are formed. As shown in FIG.
The boss can be freely formed at a necessary place. Further, in FIG. 5, the bottom portion 32 is planar, but a step portion having an arbitrary shape may be formed.

FIG. 6 is a sectional view taken along the line AA of the molded body 31 of FIG. 5. The thickness is w, and three different types of bosses are shown on the peripheral wall. The boss 35 rises vertically from the middle of the inner surface of the peripheral wall 33, the boss 35 ′ extends along the inner surface of the peripheral wall 33, and the boss 36 rises independently from the bottom 32. The boss height refers to a height from a main surface where the boss portion is integrally formed and protrudes. For example, FIG.
The height of the boss 36 is the height H from the bottom, and the boss 3
The heights of 5, 35 'refer to the protruding height of the peripheral wall portion 33 from the inner surface.

FIG. 3 is a schematic structural explanatory view showing an example of a rough forging die in a forging machine for carrying out the production method of the present invention. In FIG. 3, reference numeral 1 denotes a thin plate material having a plate thickness t made of a magnesium alloy, and is placed so as to cover a concave portion (hereinafter, also referred to as a “die portion”) 4 provided in the lower mold 2. In FIG. 3, although the thin plate material 1 having a shape slightly larger than the concave portion size is used, the mounting position changes according to the shape and size of the thin plate material to be used. It may be placed so as to have. The appropriate thickness and size of the thin sheet material 1 to be used are determined by appropriate forging conditions such as the thickness of the target compact, the height of the peripheral wall, the shape of the boss to be produced, the mold temperature and the draft. Choose a thickness and size. In the present invention, the sheet thickness uses a magnesium alloy thin plate of 1.5 mm or less,
Usually, it is preferable to use a thin plate material whose size is equal to or slightly larger than the surface area of the molded product to be obtained. Reference numeral 3 denotes an upper die, which has a convex portion (hereinafter also referred to as a “punch portion”) 5 corresponding to the die of the lower die 2. 6, 7,
Reference numeral 7 'is a depression provided in the center and shoulder of the punch 5 corresponding to the boss to be formed. Due to the presence of the depression, a rough forged molded article having the boss is formed during rough forging. You.

In the present invention, the corner radius of the die (recess) 4 of the lower die 2 to be subjected to rough forging and the upper die 3 punch (protrusion) 5 in order to prevent cracks and the like from occurring at the corners. The shoulder radius at the time of rough forging, the behavior close to the drawing process at the beginning of rough forging is performed smoothly, and a good metal flow at the time of forging is secured, and the radius of the corner of the molded body by finish forging is 0.5 mm or less Is preferable, a radius of 1 to 5 mm is preferable.

FIG. 4 shows a main part of the forging die.
Is a lower mold, and 44 is a nest inserted into the lower mold 42 exactly without any gap. 43 is an upper die, 45 is a punch part. Reference numerals 46, 47 and 47 'denote depressions corresponding to necessary portions in the completed molded body 31. Reference numeral 41 denotes a rough forged product, which is mounted on a lower die portion.

In the present invention, the magnesium alloy may be oxidized even after forging and lose its metallic luster. For this reason, for example, temporary corrosion protection, painting, etc. are performed, but particularly by forming an oxide film by anodic oxidation film treatment, excellent corrosion protection and metal luster utilizing the alloy base material that cannot be obtained by ordinary coating. It is preferable to use a magnesium alloy thin molded body having the following formula. The magnesium alloy thin molded body of the second embodiment is suitable for use as a thin enclosure for reducing the weight of various devices, and is used for a mobile phone enclosure, a mobile personal computer enclosure, and a notebook personal computer. It can be wide, such as a housing.

[0042]

(Embodiment 1) First, a concave portion (die portion) of a lower mold.
Rough forging die with a rising inner corner radius and a 3.5 mm radius of a convex part (punch part) shoulder of the upper mold, and a rising inner corner radius and an upper die with a concave part (die part) of a lower mold. And a die for finish forging with a shoulder (punch portion) shoulder radius of 0.8 mm. At the four corners of the punch of the prepared upper die for rough forging, cutouts of a size slightly larger than 3 mm x 3 mm x 4 mm in depth are formed. At the four corners of the punch of the upper die for finish forging, A notch of 3 mm × 3 mm × 4 mm in depth corresponding to the target boss size is formed. Next, a plate thickness of 1.5 mm, 55 × 160 m
The m plate-shaped AZ31 magnesium alloy sheet material was charged into an electric heating furnace filled with argon gas, and was uniformly heated to 400 ° C. Next, the material was taken out of the electric heating furnace, placed on the die of the lower mold, and subjected to rough forging at a mold temperature of 400 ° C., a forging speed of 200 mm / sec, and a molding load of 10 ton / cm ² . As a result, the bottom area is 50 × 155.
mm, the effective height of the peripheral wall is 6 mm, and the wall thickness of the main part is 1.2
mm, a rough forged product having bosses at the four corners and having no defects in appearance was obtained. Next, the obtained rough forged molded body was charged into an electric heating furnace and uniformly heated to 350 ° C.
50 ° C, forging speed 50mm / sec, forming load 10ton /
As a result of finishing forging under the forging condition of cm ² , the bottom area was 50 × 155 mm, the effective height of the peripheral wall was 6 mm, the wall thickness of the main portion was 1.0 mm, and the inner radius of the rising portion was about 0.8.
Thus, a magnesium alloy thin molded body having a good appearance and having boss portions each having a size of 3 mm × 3 mm × 4 mm in height at four corners was obtained.

(Example 2) First, a concave portion (die portion) of the lower die was raised at an inner corner radius of 5.2 mm, and a radius of a convex portion (punch portion) shoulder of the upper die was 5.0 mm for rough forging. Prepare a die and a finish forging die in which the radius of the raised inner corner of the concave portion (die portion) of the lower die is 1.0 mm and the radius of the shoulder portion of the convex portion (punch portion) of the upper die is 1.0 mm. did. Four corners and center of long side of punch part of prepared upper die for rough forging 2
Notches with a size slightly larger than 4 mm x 4 mm x 6 mm in depth are formed in the four places, and the target boss part is located at the four corners of the punch tip of the upper die for finish forging and two places in the center of the long side. 4mm x 4mm x 6mm depth corresponding to the dimensions
Is formed. 1.2mm thickness, 18
A flat AZ31 magnesium alloy sheet material of 0 × 220 mm was charged into an electric heating furnace filled with argon gas, and was uniformly heated to 450 ° C. Next, the material was taken out of the electric heating furnace, placed on the die of the lower mold, the mold temperature was 400 ° C., the forging speed was 200 mm / sec, and the molding load was 10 t.
As a result of forging under the same forging condition of on / cm ² , the bottom area was 170 × 210 mm, and the effective height of the peripheral wall was 8 m.
m, the main part had a thickness of 0.7 mm, and bosses were provided at a total of six places at the four corners and the central part of each long side, so that a rough forged thin molded body having no problem in appearance was obtained. Next, the obtained rough forged compact was charged into an electric heating furnace and heated to 350 ° C.
0 ° C, Forging speed 50mm / sec, Forming load 10ton / c
As a result of finishing forging under the forging condition of m ² , the bottom area was 1
70 × 210 mm, effective height of peripheral wall is 8 mm, wall thickness of main part is 0.6 mm, inner radius of rising part is about 1.0
A boss having a size of 4 mm × 4 mm × a height of 6 mm was formed at the four corners of each of the four corners and at the center of each long side.

(Example 3) First, a rough forging die in which the radius of the rising inner corner of the concave portion (die portion) of the lower die and the radius of the shoulder portion of the convex portion (punch portion) of the upper die is 2.5 mm. A finish forging die was prepared in which the radius of the raised inner corner portion of the concave portion (die portion) of the lower die and the radius of the shoulder portion of the convex portion (punch portion) of the upper die were 0.7 mm. Notches of a size slightly larger than 3 mm x 3 mm x depth of 5 mm are formed at two positions 5 mm inward from both ends of the punch for the rough forging prepared at the inside of the long side of the punch (total of 4 positions). Notches of 3 mm × 3 mm × 5 mm in depth corresponding to the target boss dimensions are formed at two positions 5 mm inside from both ends of the punch of the upper die for use at the inside (both 4 positions). I have. Further, a plurality of steps having a step of 0.3 mm were formed on the tip end face of the die for finish forging corresponding to the positions where the final molded body was machined and removed. Board thickness 1.0m
An AZ31 magnesium alloy sheet material having a thickness of 100 mm x 100 mm was placed in an electric heating furnace filled with argon gas and uniformly heated to 430 ° C. Next, the material is taken out of the electric heating furnace, and placed on the die of the lower mold,
As a result of performing rough forging under a forging condition of a mold temperature of 380 ° C., a forging speed of 200 mm / sec, and a molding load of 10 ton / cm ² ,
The approximate area of the bottom is 95 x 95 mm, the effective height of the peripheral wall is 7 mm, the wall thickness of the main part is 0.7 mm, the bosses are located at 5 places from the center of each long side peripheral wall and 5 mm from the center. No rough shaped body was obtained. Next, the obtained rough shaped body was charged into an electric heating furnace and heated to 430 ° C., a mold temperature of 380 ° C., a forging speed of 50 mm / sec, and a forming load of 7 t.
As a result of finishing forging under on / cm ² forging conditions, the area of the bottom was 95 × 95 mm, the effective height of the peripheral wall was 7 mm,
The wall thickness is 0.65 mm and the inside radius of the rising portion is about 0.5 mm.
7 mm, 5 mm from both corners of each long side peripheral wall, 3 mm x 3 mm x 5 mm high bosses at 4 positions from the center, and
A thin molded body made of a magnesium alloy having no external defects and having a predetermined step formed on the outer surface of the bottom of the molded body, which was not found in the rough forged molded body, could be obtained. When the boss is formed on the side as in the present embodiment, the boss can be molded with higher reproducibility than when the boss is formed on the corner. Although the reason is not clear, it is considered that the best metal flow is at the center of the side, and the metal flow is less likely to occur as it goes to the corner.

(Embodiment 4) First, the inner radius of the rising inner corner of the concave portion (die portion) 4 of the lower mold and the convex portion (punch portion) 5 of the upper mold in FIG. A rough forging die and a finish of a lower die having a nest 44 in FIG. 4 with a raised inner corner radius (die portion) and a raised portion (punch portion) shoulder radius of 0.5 mm of the upper die. A forging die was prepared. In the four corners of the punch part of the prepared upper die for rough forging, a dent corresponding to the boss 37 was formed in the molded body 31 by 3 mm × 3 m.
mx a depth slightly larger than 4 mm, and 3 mm ×
Notch vertically falling at 3 mm, 35 'of molded body 31
The size corresponding to 3 mm × 3 mm × depth slightly larger than 3 mm × 3 mm × depth 6 mm is formed at a position corresponding to the boss 36 substantially at the center of the bottom of the molded body. ing. Notches of 3 mm x 3 mm x 4 mm depth corresponding to the target boss dimensions at the four corners of the punch tip of the upper die for finish forging and the peripheral wall, and 3 mm x 3 mm x 9 mm depth at the bottom center. Is formed. Next, a AZ31 magnesium alloy sheet material having a thickness of 1.5 mm and a size of 75 × 165 mm was placed in an electric heating furnace filled with argon gas and uniformly heated to 400 ° C. Next, the material was taken out of the electric heating furnace, placed on the die of the lower mold, and subjected to rough forging at a mold temperature of 400 ° C., a forging speed of 200 mm / sec, and a molding load of 10 ton / cm ² . As a result, the bottom area is 55 × 150
mm, effective height of the peripheral wall is 10 mm, and wall thickness of the main part is 1.2
In the four corners, a boss 35 perpendicular to the inner surface of the peripheral wall and a boss 35 ′ of 3 mm × 3 mm × 4 mm in height along the inner surface of the peripheral wall are provided at the four corners, and a boss 35 ′ having a height of 3 mm along the inner surface of the peripheral wall. Is a boss 36 of 3 mm x 3 mm x 6 mm height
A rough forged compact having no defects in appearance was obtained. Next, the obtained roughly forged molded body was charged into an electric heating furnace, and 3
Heat uniformly to 50 ° C, mold temperature 350 ° C, forging speed 50
As a result of performing forging under a forging condition of mm / sec and a forming load of 10 ton / cm ² , the bottom area is 50 × 155 mm, the effective height of the peripheral wall is 10 mm, the main part thickness is 1.0 mm, and the inner radius of the rising portion is Approximately 0.5mm, 3mm × 3 at four corners
mm x height 4mm, 3mm x 3mm on the peripheral wall 33 respectively
× Boss 35, 35 'with a height of 4mm, and 3 at the bottom center
A magnesium alloy thin molded body having a good appearance having a boss of mm × 3 mm × 9 mm in height and having a radius of 0.5 mm in at least one of the inner corner and the outer corner of the molded body was obtained.

(Example 5) First, the radius of the inner corner of the concave portion (die portion) of the lower mold rising 3.5 mm in FIG. 3 and the radius of the shoulder portion of the convex portion (punch portion) of the upper mold 3.0 mm in FIG. A rough forging die and a concave (die portion) rising inner corner radius of the lower die having a nest shown in FIG. 4 having a radius of approximately 0 mm and a convex portion (punch portion) shoulder radius of the upper die of 0.5 mm. A finish forging die was prepared. At the four corners of the punch tip of the prepared upper die for rough forging, a notch with a size slightly larger than 4 mm x 4 mm x 5 mm deep is placed at a position corresponding to the center of the bottom at 3 mm x
A notch having a size slightly larger than 3 mm × 7 mm in depth is formed. At the four corners of the punch tip of the upper die for finish forging, 3 mm x
A 3 mm × 3 mm × 9 mm height is formed at a position corresponding to a cutout portion of 3 mm × 5 mm depth and a bottom center portion. AZ with a plate thickness of 1.2 mm and 180 × 220 mm
The 31 magnesium alloy thin plate material was charged into an electric heating furnace filled with argon gas, and was uniformly heated to 450 ° C. Next, the material was taken out of the electric heating furnace, placed on the die of the lower die, and the die temperature was 400 ° C. and the forging speed was 20 ° C.
As a result of forging under the same forging conditions of 0 mm / sec and a molding load of 10 ton / cm ² , the bottom area was 150 × 190 m.
m, effective height of peripheral wall is 10mm, main part thickness 0.7m
m, four bosses at the four corners were satisfactorily filled, but the boss at the bottom center was a little insufficiently filled. Apart from this, a rough-forged thin-walled compact having no problem in appearance was obtained. Next, the obtained rough forged molded body was charged into an electric heating furnace and heated to 350 ° C., and forged under a forging condition of a mold temperature of 350 ° C., a forging speed of 50 mm / sec, and a forming load of 10 ton / cm ^2. As a result, the bottom area was 170 × 210
mm, the effective height of the peripheral wall is 10 mm, and the thickness of the main part is 0.1 mm.
A good boss of 3 mm x 3 mm x 5 mm in height was posted at 6 mm, the inner radius of the rising portion was about 0.5 mm, and the four corners, but the center boss at the bottom was 3 mm x 3 mm x 9 mm in height.
Was insufficiently filled, was defective as a boss, and was defective as a molded article. It is considered that the cause was that the height of the boss at the center of the bottom exceeded ten times the thickness of the main part of the finished molded product.

Embodiment 6 First, a rough forging in which the radius of the inner corner of the concave portion (die portion) of the lower mold and the shoulder of the convex portion (punch portion) of the upper mold in FIG. 3 is 2.5 mm. In FIG. 4, the radius of the inner corner portion of the concave portion (die portion) of the lower die having the nest in FIG. 4 is approximately 0 mm, and the radius of the shoulder portion of the convex portion (punch portion) of the upper mold is 0.3 mm. A finish forging die was prepared. At two positions (in total, four positions) inside 5 mm from both ends of the punched part of the prepared upper die for rough forging, corresponding to a notch part having a size slightly larger than 3 mm × 3 mm × depth 5 mm and a bottom center. 3mm in place
A recess having a size of 3 mm x a depth of 5 mm is formed. At two positions 5 mm inside from both ends of the upper die of the upper die for finish forging (four places in total), 3 mm corresponding to the target boss size is provided. Notch part of × 3mm × depth 5mm,
3mm x 3mm x 6mm deep at the location corresponding to the bottom center
Are formed. Board thickness 1.0mm, 100x
A 100 mm flat plate-shaped AZ31 magnesium alloy sheet material was charged into an electric heating furnace filled with argon gas,
Heated uniformly to 430 ° C. Next, the material is taken out of the electric heating furnace, placed on the die of the lower mold, and the mold temperature 3
80 ° C, Forging speed 200mm / sec, Molding load 10ton
As a result of performing rough forging under the forging conditions of / cm ² , the approximate area of the bottom is 95 × 95 mm, the effective height of the peripheral wall is 7 mm, the wall thickness of the main part is 0.7 mm, and the center of each long side peripheral wall is 5 mm from the center. A molded article having bosses at four positions and a central portion of the bottom and having no defects in appearance was obtained. Next, the obtained rough shaped body was charged into an electric heating furnace and heated to 430 ° C.
Mold temperature 380 ° C, forging speed 50mm / sec, molding load 7
As a result of finishing forging under the forging conditions of ton / cm ² , the area of the bottom was 95 × 95 mm, and the effective height of the peripheral wall was 7 m.
m, the wall thickness is 0.65mm, the inner radius of the rising part is about 0.3mm, and the boss of 3mm x 3mm x 5mm height is placed at 4 places from the center of 5mm from both corners of each long side peripheral wall at the bottom center. A thin molded body made of a magnesium alloy having a boss of 3 mm × 3 mm × 6 mm in depth and having no defect in appearance was obtained. When the boss is formed on the side as in the present embodiment, the boss can be molded with higher reproducibility than when the boss is formed on the corner. The reason for this is not clear, but it is considered that the best metal flow is at the center of the side, and metal flow is less likely to occur toward the corners.

In the embodiments described in the first to sixth embodiments, the concave portion (die portion) is formed in the lower die, and the convex portion (punch portion) is formed in the upper die. A mold having a configuration may be used. That is, a thin sheet made of a magnesium alloy or a roughly forged product may be placed on a punch portion (convex portion) formed in the lower die and molded.

[0049]

The thin-walled product made of a magnesium alloy of the present invention is even lighter than the aluminum alloy-made compact,
It also has rigidity, and is particularly useful as a small housing. In particular, since the inside radius of the molded body is small, the internal capacity increases. In addition, since the boss portion is integrally formed at a required location up to 10 times the thickness of the main portion of the completed molded body, a molded body having higher reliability than a molded body produced by bonding or the like by a conventional manufacturing method can be obtained. There are benefits to be gained. In addition, it is also possible to obtain a product with metallic luster utilizing the magnesium alloy base by performing appropriate coating treatment, and as a material suitable for use as a thin-walled enclosure for the purpose of reducing the weight of various devices, It can be expected to be widely applied to mobile phone cases, mobile personal computer cases, and notebook personal computer cases.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a main part configuration according to a method of manufacturing a thin-walled product made of a magnesium alloy of the present invention.

FIG. 2 is a schematic perspective view showing one example of a thin-walled product made of a magnesium alloy of the present invention.

FIG. 3 is a schematic explanatory view of a main part of a rough forging according to a method of manufacturing a thin-walled product made of a magnesium alloy of the present invention.

FIG. 4 is a schematic explanatory diagram of a main part of a finish forging according to a method for manufacturing a thin-walled product made of a magnesium alloy of the present invention.

FIG. 5 is a schematic structural perspective view showing an example of a thin molded product made of a magnesium alloy of the present invention.

FIG. 6 is an explanatory diagram showing an AA cross section of FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 magnesium alloy sheet material 2 lower die for rough forging 3 upper die for rough forging 4 concave part (die) of lower die 5 convex part (punch) of upper die 6 depression corresponding to boss part 7, 7 'boss part Corresponding notch 11 Magnesium alloy thin plate material 12 Lower mold 13 Lower mold recess 14 Upper mold 15 Upper mold protrusion 16 Heater 17 Thermocouple 18 Notch corresponding to boss 21 Thin magnesium alloy Formed part 22 Bottom part 23 Peripheral wall part 24 Rise corner part 25 Corner part 26 Boss part 31 Thin molded body made of magnesium alloy 32 Bottom part 33 Peripheral wall part 34 Inner corner part 35, 35 'Boss 36 Boss 37 Corner boss 38 Outer corner part 41 Rough forging Molded body 42 Lower die for finish forging 43 Upper die for finish forging 44 Insertion of lower die 45 Convex part (punch) 46 of upper die 46 Depression corresponding to boss part 47, 47 ' Cutout w finished molded body wall thickness H boss height corresponding to the part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Watanabe 1-2-1 Shibaura, Minato-ku, Tokyo Within Hitachi Metals Co., Ltd. (72) Inventor Babao Hama 11 Kinuigaoka, Moka City, Tochigi Prefecture Hitachi Metals, Ltd. F-term in Shikisha Materials Research Laboratory (reference) 4E087 AA02 AA10 BA03 BA19 CA15 CB02 CB04 CB16 DA04 EA11 EB03 EC11 ED01 ED13 ED14 FB06 HB06 4E360 AB02 AB51 EE13 EE15 GB26 GB46 GC04

Claims (19)

[Claims] 1. A thin magnesium alloy body formed by forging a magnesium alloy thin sheet material. 2. The thin-walled molded product has a main part thickness of 1.5.
2. The thin molded product made of a magnesium alloy according to claim 1, wherein the thickness is not more than mm. 3. The thin-walled molded body has a peripheral wall portion, and a chamfer or a radius of the rising inner corner portion and / or the outer corner portion of the peripheral wall portion is 1 mm or less. Item 3. A thin molded product made of a magnesium alloy according to Item 2. 4. The thin formed body made of a magnesium alloy according to claim 3, wherein the height of the peripheral wall portion is 30 mm or less. 5. The magnesium alloy thin wall according to claim 1, wherein the thin walled body has one or more bosses thicker than the main part. Molded body. 6. The magnesium alloy thin molded body according to claim 5, wherein the boss portion has a thickness of 10 times or less the main part thickness of the thin molded body. 7. The thin-walled molded product has a numeral,
The magnesium alloy thin molded product according to any one of claims 1 to 6, further comprising a convex portion formed of any one or more of a symbol, a mark, and a pattern. 8. The magnesium alloy thin molded body according to claim 7, wherein the convex portion has a rear surface which is not concave. 9. The thin-walled molded product has a thickness of 0.3 to 0.8 mm.
The thin-walled product made of a magnesium alloy according to any one of claims 1 to 8, wherein the thin-walled portions are intermittently and / or continuously unevenly distributed. 10. The magnesium alloy thin molded body according to claim 1, wherein the thin molded body is a housing. 11. The magnesium alloy thin molded article according to claim 1, wherein the thin molded article is used for an electronic device. 12. The magnesium alloy thin molded body according to claim 11, wherein the thin molded body is for a mobile phone. 13. The thin molded product made of a magnesium alloy according to claim 11, wherein the thin molded product is for a mobile personal computer. 14. The magnesium alloy thin molded article according to claim 11, wherein the thin molded article is for a notebook personal computer. 15. A magnesium alloy thin sheet material having a sheet thickness of 3 mm or less is roughly forged at a forming load of 1 to 30 ton / cm ² , a forging speed of 1 to 500 mm / sec, a reduction of 75% or less, and a reduction of 50% or less. Finish forging with a main part thickness of 1.5
mm or less. 16. A magnesium alloy thin plate material of 200
Up to 540 ° C, radius of punch shoulder of rough forging die (r1)
Alternatively, the ratio of the die corner radius (r2) to the punch shoulder radius (r3) or die corner radius (r4) of the finish forging die, and r1 (or r2) / r3 (or r4) is 7 or less. The forging is performed by using a set die, and a chamfer or a radius of a rising inner corner portion and / or an outer corner portion of the peripheral wall portion of the completed molded body is set to 1 mm or less.
6. The method for producing a magnesium alloy thin molded body according to 5. 17. A rough forging in which a punch or a die is forged using a mold having at least one recessed portion to form a rough forged product having a boss portion, and the rough forged product is formed by a punch or a die. 17. A boss having a boss height of 10 times or less of a thickness of a main portion by forging using a mold having a concave portion corresponding to the boss portion. A method for producing a thin molded body made of a magnesium alloy. 18. The magnesium alloy thin molded body according to claim 17, wherein the height of the boss portion after the finish forging is 7 times or less the thickness of the magnesium alloy thin plate material. Production method. 19. The magnesium alloy thin sheet material has a thickness of 3 mm or less, and the rough forging die has a thickness of 100 to 5 mm.
Heated and maintained at 40 ° C., and the finish forging die is 100 to
The method for producing a thin-walled body made of a magnesium alloy according to any one of claims 15 to 18, wherein the body is heated and held at 540 ° C.