JP4735866B2 - Magnesium alloy member and manufacturing method thereof - Google Patents

Description

  The present invention relates to a magnesium alloy member that can be suitably used for a casing of a portable electric device and the like, and a manufacturing method thereof.

  Magnesium alloys containing various additive elements in magnesium have been used as materials for casings of portable electric devices such as mobile phones and notebook computers and members of automobile parts.

  Magnesium alloys have a hexagonal crystal structure (hcp structure) and are therefore poor in plastic workability at room temperature. Therefore, magnesium alloy members such as the above-mentioned cases are mainly cast materials by die casting or thixomolding. . Recently, it has been studied to press a plate made of a magnesium alloy for extension represented by ASTM standard AZ31 alloy to form the casing (for example, see Patent Documents 1 and 2). Further, a plate made of ASTM standard AZ91 alloy and excellent in press workability has been studied (for example, see Patent Document 3).

JP 2001-105029 A JP 2002-239644 A JP 2007-098470 A

  The casing is generally attached with various retrofit components (for example, a substrate on which an IC chip is mounted, a monitor, or the like) depending on the usage mode, and it is desirable to have an attachment portion for the retrofit components. However, since the magnesium alloy has poor plastic workability, it is difficult to form a minute shape such as a mounting portion of a part by press molding. In addition, when using casting such as die casting, the shape of the mold corresponding to the portion to be the mounting portion becomes complicated, the molten metal does not spread sufficiently to the finely shaped mold, and the desired mounting portion may not be formed. is there. In addition, in order to directly attach the retrofit component to the magnesium alloy plate, for example, it is impossible to form a screw hole in the alloy plate due to the poor plastic workability of the magnesium alloy.

  Moreover, the edge part of an alloy plate may have a sharp angle | corner, It is easy to damage and there also exists a problem that handling is required.

  Then, one of the objectives of this invention is providing the magnesium alloy member provided with the resin member which can attach retrofitting components, and its manufacturing method. Moreover, the other object of this invention is to provide the magnesium alloy member which can protect an edge part, and its manufacturing method.

  The magnesium alloy member of the present invention includes a rolled plate of a magnesium alloy containing 5.8 to 10% by mass of Al, and a resin member joined to an edge of the rolled plate.

  Here, the edge portion is a portion including a contour line of one surface of the rolled sheet, a contour line of the other surface, and a surface sandwiched between both contour lines. The contour line includes not only the contour line of the outer peripheral edge of the rolled plate but also the contour line of the through hole if a through hole is formed in the rolled plate. Moreover, the resin member does not need to be provided in all the edge parts in a rolled sheet, and may be provided only in a part of edge part.

  By setting it as the structure of this invention, the resin member is joined to the edge of the rolled plate which consists of magnesium alloys, and this resin member can be utilized as an attachment part of retrofitting components. Moreover, by setting it as the structure of this invention, while the resin member protects the edge of a rolled sheet, it can prevent that the handler of an alloy member is injured by the sharp edge of a rolled sheet. Hereinafter, the configuration of the present invention will be described in more detail.

  In the magnesium alloy member of the present invention, when the resin member spreads from the edge to at least one of the one side and the other side of the rolled plate, the bonding area with the rolled plate is increased and the resin plate is caught by the rolled plate. Therefore, it becomes difficult to come off the rolled sheet. In particular, the resin member is preferably arranged so as to extend from a part of one surface of the rolled plate to a part of the other surface through the edge. In this case, since the resin member is securely engaged with the rolled plate, even if the resin member is used as an attachment part of a retrofitted part or used to protect the edge of the rolled plate, the resin member There is almost no risk of coming off the rolled sheet.

<Material of rolled plate>
An Mg—Al alloy containing Al, which is a magnesium alloy constituting the rolled plate, has high corrosion resistance. Examples of Mg-Al alloys include AZ alloys (Mg-Al-Zn alloys, Zn: 0.2 to 1.5 mass%) and AM alloys (Mg-Al-Mn alloys, Mn: 0.15 to 0.5 mass%), AS alloy (Mg—Al—Si alloy, Si: 0.6 to 1.4 mass%), Mg—Al—RE (rare earth element) alloy, etc. Is mentioned. The amount of Al contained is 5.8 to 10% by mass, and typical examples include AZ60, AZ80, and AZ91. In particular, an AZ91 equivalent material containing 8.3 to 9.5% by mass of Al (for example, AZ91E; containing 8.3 to 9.2% by mass of Al, AZ91D; Al 8.5 to 9.5% by mass of Al) Is superior in mechanical properties such as strength and resistance to cracking during plastic deformation and corrosion resistance, as compared with an AZ31 equivalent material having an Al content of 2.5 to 3.5% by mass. High corrosion resistance allows the use of highly polar resins, highly hygroscopic resins, resins with high acid / amine values, etc. as resin material materials described in the next stage. The range of choices expands.

<Material of resin member>
The material of the resin member may be appropriately selected according to the use of the magnesium alloy member of the present invention in consideration of the hardness, corrosion resistance, durability, heat resistance, etc. of the material, and is not particularly limited. For example, thermoplastic resin and thermosetting resin, specific examples include polypropylene resin, polyethylene resin, polystyrene resin, polyvinyl chloride resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polycarbonate resin, acrylic resin, epoxy resin, phenol Examples thereof include a resin and a silicone resin. Examples of the resin member material include rubber materials, specifically, natural rubber, or synthetic rubber such as isoprene rubber, styrene rubber, nitrile rubber, chloroprene rubber, acrylic rubber, silicone rubber, and urethane rubber. A filler, a color batch, or the like may be blended with the resin member made of these materials.

<Engagement between rolled plate and resin member>
As a specific example of the joining state of the rolled plate and the resin member, for example, a through hole penetrating from one surface of the rolled plate to the other surface is formed, and a resin member is provided so as to be in contact with the inner surface of the through hole. Is mentioned. For example, FIG. 1A shows an example in which a through hole 2H is formed in the rolled plate 2, and a resin member 3 is provided so as to fill the through hole 2H. Moreover, as shown in FIG.1 (B), by arrange | positioning the resin member 3 so that the through-hole 2H may be filled, it is made to spread along one surface 2A and the other surface 2B of the rolled plate 2, The rolled plate 2 and the resin member 3 may be firmly engaged. Further, as shown in FIG. 1C, the resin member 3 may be provided so as to reach the side edge from the through hole 2H of the rolled plate 2 through the one surface 2A and the other surface 2B.

  As another specific example of the engagement state between the rolled plate and the resin member, for example, at least one of a concave portion and a convex portion is formed on the rolled plate, and the resin member is formed so as to cover the concave portion or the convex portion. Is mentioned. For example, FIG. 2A shows an example in which the edge of the rolled plate 2 is bent to form a convex portion, and the resin member 3 is formed so as to cover the convex portion. The convex portion in FIG. 2A is an L-shaped portion that protrudes toward the other surface 2B of the rolled plate 2, and the resin member 3 includes one of the two surfaces 2A of the rolled plate 2 including the convex portion. It is formed so as to cover a part and a part of the other surface 2B.

  Furthermore, as an example of engagement between the concave and convex portions formed on the rolled plate and the resin member, the one shown in FIG. In FIG. 2 (B), the surface properties of a part of one surface 2A of the rolled sheet 2 including the edge part and a part of the other surface 2B are roughened so as to cover the concave and convex parts formed thereby. An example in which the resin member 3 is engaged is shown. In this case, the concave portion and the convex portion are formed by physical means such as shot blasting or cutting (for example, hairline processing) or chemical means such as acid etching. The concave portion and the convex portion may be applied only to a portion of the rolled plate 2 that is covered with the resin member 3. You can do it from

  In addition, as shown in FIG. 2 (C), a resin member is formed so that a concave portion is formed by roughening the inner peripheral surface of the through hole 2H of the rolled plate 2, and the through hole 2H including the inner peripheral surface is filled. 3 may be arranged. Of course, the resin member 3 of FIG. 2 (C) may be spread over one surface 2A and the other surface 2B of the rolled plate 2.

<Thickness of resin member>
The thickness of the resin member can be appropriately selected according to the purpose of use of the resin member (utilization as an attachment portion, protection of an edge portion), and is not particularly limited. Preferably, the resin member has a thickness that can maintain the bonding with the rolled plate. For example, when the resin member spreads along one surface and the other surface of the rolled plate, the thickness of the resin member in the spread portion is preferably 0.5 mm or more. If it is the resin member of this thickness, even if it selects any of the resin material mentioned above, the deformation | transformation which remove | deviates from a rolled sheet does not occur.

<Shape of resin member>
The shape of the resin member may be appropriately selected according to the use of the alloy member, and is not particularly limited. For example, if the purpose is to protect the edge of the rolled plate, the resin member may have a rounded shape with no corners. In addition, if the resin member is used as a mounting portion for the retrofitted component, the resin member and the retrofitted component may be formed in a shape that can be mechanically joined.

  For example, as shown in FIG. 3 (A), a resin member 3 that engages with the through hole of the rolled plate 2 is provided, and a portion protruding from the rolled plate 2 of the resin member 3 is threaded to form a male screw portion ms. What is necessary is just to form. If it does in this way, the rear part 4 can be attached to the alloy member 1 by screwing the male thread part ms of the resin member 3 and the female thread part fs of the rear part 4 (in this figure, a nut is illustrated). On the contrary, as shown in FIG. 3B, if the resin member 3 engaged with the rolled plate 2 is threaded to form the female screw portion fs, the retrofitted component 4 (in this figure, a bolt is illustrated. ) Can be easily screwed into the male screw part ms. In addition, as shown in FIG. 3 (C), a taper portion t is formed at the end of the resin member 3 that engages with the rolled plate 2, and a fitting recess c that matches the shape of the taper portion t is formed as a retrofitting component 4. It may be formed in the form. Of course, the taper portion t may be formed in the retrofitting component 4 and the fitting recess c may be formed in the resin member 3. According to these configurations, it is easy to attach the retrofit component 4 to the magnesium alloy member 1, and the retrofit component 4 is difficult to be detached from the alloy member 1. Note that the resin member 3 in FIGS. 3A to 3C is bonded to the surface of the edge of the rolled plate 2 even if it does not spread on one side and the other side of the rolled plate 2. So it does not come off easily.

<Others>
The volume ratio of the magnesium alloy in the magnesium alloy member is preferably 80 to 95%. That is, the volume ratio of the resin member in the magnesium alloy member is preferably 5 to 20%. When there are too many resin members, there is a possibility that the rigidity required for the magnesium alloy member may not be satisfied. Here, when the volume ratio of the magnesium alloy in the magnesium alloy member is in the above range, the specific gravity of the alloy member is reduced, and the weight of the device using the alloy member of the present invention can be reduced. When the volume ratio is set as described above, the specific gravity of the magnesium alloy member including the rolled sheet and the resin member is approximately 1.6 to 1.75. For example, if a polypropylene having a specific gravity of 0.9 (Novatech PP-MA3 (trade name; manufactured by Nippon Polychem Co., Ltd.) occupies 20% by volume of the alloy member, the specific gravity of the alloy member will be about 1.6 (equivalent to AZ91) The specific gravity of the material is about 1.8).

<Method for Producing the Magnesium Alloy Member of the Present Invention>
As a method of manufacturing a magnesium alloy member by attaching a resin member to a rolled plate of magnesium alloy, there is a method of manufacturing a magnesium alloy member by curing the resin after attaching an uncured resin to the rolled plate. . For example, it is possible to use press molding in which uncured resin is placed on a rolled plate and sandwiched between molds, or insert molding in which a rolled plate is placed in a mold and uncured resin is injected into the mold. . When an uncured resin is used, the resin is in close contact with the edge of the rolled plate when the resin is cured.

  On the other hand, there is a method of preparing a magnesium alloy member by separately preparing a rolled plate and a resin member that has already been cured and fitting the resin member into the rolled plate. For example, a resin member having a joint surface that matches the outer diameter near the edge of the rolled plate may be fitted into the rolled plate. When the cured resin member is retrofitted to the rolled plate, the resin member reaches the other surface from one side of the rolled plate through the edge in order to engage the resin member so that it does not come off the rolled plate. It is necessary to.

  Among the methods described above, insert molding is particularly suitable for the production of the magnesium alloy member of the present invention because it is easy to give flexibility to the shape pattern of the resin member and is preferable from the viewpoint of mass productivity. Moreover, insert molding is excellent also in the point of improving the adhesiveness of the resin member with respect to a rolled sheet. Below, the manufacturing method of the magnesium alloy member of this invention is demonstrated.

  The method for producing a magnesium alloy member of the present invention includes a step of placing a rolled plate made of a magnesium alloy containing 5.8 to 10% by mass of Al in a mold, and a resin member joined to an edge of the rolled plate. And a step of insert molding a resin.

  As one form of the manufacturing method of the magnesium alloy member of the present invention, a magnesium alloy rolled plate may be obtained by a twin roll casting method. The twin roll casting method enables rapid cooling and solidification of the magnesium alloy, which can reduce the occurrence of oxides and segregation in the resulting rolled plate, and plastic processing such as pressing and bending the rolled plate in the subsequent process. When performing, it is hard to produce malfunctions, such as a crack and a crack, in a rolled sheet.

  Moreover, you may perform the plastic processing which changes the shape of a rolled sheet before or after insert molding as one form of the manufacturing method of this invention magnesium alloy member. For example, before insert molding, press working or bending may be performed to form a concave portion or a convex portion that engages with the resin member as described above.

  In the magnesium alloy member of the present invention, since the resin member is bonded to the edge of the magnesium alloy rolled plate, the resin member can be used as an attachment part for a retrofitted part. Moreover, by setting it as the structure of this invention, while the resin member protects the edge part of a rolled sheet, it can prevent that the handler of an alloy member is injured by a sharp edge part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
FIG. 4 is a schematic view illustrating a process of manufacturing the magnesium alloy member 1 of the first embodiment. FIG. 5 (A) is a three-sided view of the magnesium alloy member 1 obtained by the series of steps shown in FIG. FIG. 5B shows a state where the retrofit component 4 is attached to the magnesium alloy member 1.

  First, as shown in FIG. 4A, the dimensions are 200 mm × 300 mm × 0.8 mm, AZ91 equivalent material (Al content: 9.0 mass%, Zn content: 1.0 mass%, balance: Mg + A rolled plate 2 of magnesium alloy made of impurities) was prepared. The rolled plate 2 is obtained by a twin roll casting method, and is a rolled plate of a magnesium alloy excellent in plastic workability with little oxide and segregation inside.

  Moreover, as shown in FIG. 4A, a mold 40 for insert molding was prepared. The inside of the mold 40 can accommodate the rolled plate 2, has a shape similar to the outer diameter of the rolled plate 2, and is larger than the outer diameter of the rolled plate 2. The mold 40 is formed with an injection port 41 for injecting uncured resin into the mold 40.

  Next, as shown in FIG. 4 (B), after the rolled plate 2 was placed in the mold 40, so-called insert molding was performed in which resin was poured from the injection port 41 as shown in FIG. 4 (C). . The resin used was a polybutylene terephthalate resin (PBT resin; Toraycon 1404X31 manufactured by Toray Industries, Inc.).

  After the resin was cured, the magnesium alloy member 1 in which the rolled plate 2 and the resin member 3 were integrated was removed from the mold 40 (see FIG. 4D). When the thickness of the resin member 3 was measured, the thickness of the portion along the one surface 2A of the rolled plate 2 was 0.5 mm, the thickness of the portion along the other surface 2B was 0.5 mm, The thickness of the portion along the side surface of the plate 2 was 1.0 mm (see FIG. 5A).

  As shown in FIG. 5A, in the magnesium alloy member 1 of Embodiment 1, the resin member 3 is provided for the entire outer peripheral edge of the rolled plate 2, and the outer peripheral edge of the rolled plate 2 is formed by the resin member 3. Can be protected. On the other hand, the resin member 3 does not cover the inner side of the outer peripheral edge of the rolled plate 2 and can maintain a metal texture when the entire metal member 1 is viewed.

  Moreover, the resin member 3 of the obtained magnesium alloy member 1 has the boss | hub part b which protrudes in the thickness direction of the rolling plate 2 in the four corners of the back surface side. The boss part b is formed by transferring the shape of the mold. Then, as shown in FIG. 5B, the monitor can be easily attached to the alloy member 1 simply by fitting the boss b into the fitting holes provided at the four corners of the monitor as the retrofitted component 4. Since the resin member 3 having the boss portion b does not come out of engagement with the outer peripheral edge portion, the monitor attached to the resin member 3 is also securely attached to the alloy member 1. Note that the shape of the boss part b and the fitting hole of the monitor may be formed as the tapered part t and the fitting concave part c of FIG.

  Furthermore, when the volume ratio of the resin member 3 to the magnesium alloy member 1 in this embodiment was measured, it was 10%. The volume ratio of the resin member 3 can be obtained from the space between the mold 40 and the rolled plate 2 at the time of manufacture. And when the specific gravity of the alloy member 1 was measured from the composition of the magnesium alloy of the used rolled sheet 2, and the material of the resin member 3, it was 1.7. That is, the specific gravity is remarkably smaller than when the casing is entirely made of a magnesium alloy, and the weight of the device using the metal member 1 can be reduced.

<Embodiment 2>
FIG. 6 is a schematic view showing a manufacturing process of the magnesium alloy member 1 according to Embodiment 2, wherein (A) shows a magnesium alloy rolled plate 2 to be prepared, and (B) shows a finished alloy member 1. It is a surface view and a cross-sectional view.

  In manufacturing the magnesium alloy member 1 of the present embodiment, first, a rolled plate 2 having dimensions of 250 mm × 350 mm × 0.6 mm and made of AZ91 was prepared (see FIG. 5A). A through hole 2H having a size of 10 mm × 30 mm is formed in the center portion of the rolled plate 2 by punching.

  Next, after placing the rolled plate 2 in a mold, insert molding was performed in which a silicone rubber resin (KE951V manufactured by Shin-Etsu Chemical Co., Ltd.) was injected into the mold. Through this series of steps, a magnesium alloy member 1 as shown in FIG. 6B can be obtained. The resin member 3 in the alloy member 1 is provided so as to fill the through hole 2H of the rolled plate 2 and extends along the one surface 2A and the other surface 2B of the rolled plate 2. Match. Further, the thickness of the resin member 3 in the portion extending along the one surface 2A and the other surface 2B is 1 mm. The resin member 3 in this portion is not easily deformed, and the resin member 3 is a rolled plate. It will not deviate from 2.

  In the present embodiment, a logo is formed on the resin member 3, but this logo is formed by transferring irregularities formed on the mold. Of course, the logo may be formed by processing the resin member 3 after insert molding.

<Other embodiments>
In addition, the arrangement | positioning state of the resin member different from Embodiment 1, 2 is illustrated based on FIG.

  First, in the magnesium alloy member 1 (perspective view) shown in FIG. 7A, a through hole 2H penetrating the rolled plate 2 is formed at the center of the rolled plate 2, and the edge of the through hole 2H is entirely formed. A resin member 3 covering the circumference is provided. The resin member 3 is engaged with the rolled plate 2 by reaching from the one surface of the rolled plate 2 through the edge on the through hole 2H side to the other surface. Further, the resin member 3 is provided only in the vicinity of the edge without filling the through hole 2H provided in the rolled plate 2, and penetrates the alloy member 1 in the thickness direction at the center of the alloy member 1. A through window 20 is formed. Then, by fitting into the through window 20, the retrofit component 4 which is a substrate on which an IC chip or the like is mounted can be easily attached.

  In the magnesium alloy member 1 (perspective view) shown in FIG. 7B, through holes 2H that penetrate the rolled plate 2 are formed at the center of the rolled plate 2, and resin is formed at the four corners of the edge of the through hole 2H. A member 3 is provided. The resin member 3 is engaged with the rolled plate 2 by reaching from the one surface of the rolled plate 2 through the edge to the other surface. The resin member 3 in this figure also serves as a boss portion for attaching a monitor as a retrofitted component 4 so that the monitor can be easily attached to the alloy member 1.

  In the magnesium alloy member 1 (top view) shown in FIG. 7C, resin members 3 are provided at four corners of the rolled plate 2. The resin member 3 reaches from the one surface of the rolled plate 2 to the other surface via the edge, and is engaged with the rolled plate 2. According to this structure, the corner | angular part of the rolling plate 2 which is most easily damaged can be protected.

  Note that the present invention can be modified as appropriate without departing from the gist of the present invention, and is not limited to the configuration of the above-described embodiment. For example, the above-described embodiments may be combined. In addition, the composition of the magnesium alloy, the material of the resin member, and the like can be changed as appropriate.

  The magnesium alloy member of the present invention can be suitably used for a member to which various parts such as a portable device and a personal computer casing are desired to be attached.

It is the schematic which illustrates the joining state of the rolled plate made from a magnesium alloy, and a resin member. (A) shows an example in which a resin member is fitted into a through-hole formed in a rolled plate. (B) shows an example in which the resin member shown in (A) further spreads on one side and the other side of the rolled plate. (C) shows an example in which the resin member is arranged across the side edge of the rolled plate and the through hole of the rolled plate. It is the schematic which illustrates the joining state of the rolled plate made from a magnesium alloy, and a resin member. (A) shows the example which formed the convex part which bent the edge part of the rolled sheet. (B) shows the example which roughened the surface property of the rolled sheet and formed the unevenness | corrugation. (C) shows the example which roughened the inner surface of the through-hole of a rolled sheet, and formed the unevenness | corrugation. It is the schematic which illustrates the engagement state of the resin member and retrofitting components. (A) shows the example which formed the external thread part in the resin member, and the internal thread part in the retrofitting part. (B) shows an example in which a female screw part is formed on a resin member and a male screw part is formed on a retrofitted part. (C) shows the example which formed the taper part in the resin member, and formed the fitting recessed part in the retrofitting component. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing which illustrates the process of manufacturing the magnesium alloy member with which the rolled sheet and the resin member were united based on Embodiment 1, Comprising: The process is shown with time from (A) to (D). (A) is a three-sided view of a magnesium alloy member (upper left is a front view, lower left is a back view, and lower right is a side view). (B) is explanatory drawing which shows a mode that a monitor (retrofitting component) is attached to a magnesium alloy member. It is the schematic which shows the process of manufacturing the magnesium alloy member which concerns on Embodiment 2, Comprising: (A) is the schematic of the prepared rolled sheet, (B) is the surface figure and cross-sectional view of the completed magnesium alloy member. Show. It is a magnesium alloy member which concerns on other embodiment, Comprising: (A) is the example which engaged the resin member to the perimeter of the through-hole formed in the center part of a rolled sheet, (B) is the center of a rolled sheet (C) shows an example in which the resin member is engaged with the four corners of the outer peripheral edge of the rolled plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnesium alloy member 2 Rolled sheet 2A One surface of a rolled sheet 2B The other surface of a rolled sheet 2H Through-hole 20 Through-window 3 Resin member 4 Retrofit part 40 Die 41 Inlet ms Male thread part fs Female thread part t Taper part c Fitting Joint recess b Boss

Claims (8)

A magnesium alloy rolled plate containing 5.8 to 10% by mass of Al;
A resin member joined to an edge of the rolled plate;
Equipped with a,
The said resin member has an engaging part formed in the shape which can attach a retrofit component mechanically to the resin member, The magnesium alloy member characterized by the above-mentioned.   2. The magnesium alloy member according to claim 1, wherein the resin member extends from a part of one surface of the rolled plate to a part of the other surface through an edge.   The magnesium alloy member according to claim 1 or 2, wherein the rolled sheet has an Al content of 8.3 to 9.5 mass%.   The magnesium alloy member according to any one of claims 1 to 3, wherein a volume ratio of the magnesium alloy in the magnesium alloy member is 80 to 95%. The rolled plate has a through-hole penetrating from one surface to the other surface,
The said resin member is provided so that the inner surface of the said through-hole may be contacted, The magnesium alloy member of any one of Claims 1-4 characterized by the above-mentioned. The rolled plate comprises at least one of a concave portion and a convex portion,
The said resin member is provided so that the said recessed part or convex part may be covered, The magnesium alloy member of any one of Claims 1-5 characterized by the above-mentioned. Arranging a rolled plate made of a magnesium alloy containing 5.8 to 10% by mass of Al in a mold;
The so rolled sheet resin member to the edge of bonding, comprising the steps of insert-molding the resin, the
The method for producing a magnesium alloy member, wherein the resin member is provided with an engagement portion formed in a shape to which a retrofit component can be mechanically attached .   The method for producing a magnesium alloy member according to claim 7, further comprising a step of obtaining the rolled sheet by twin roll casting.

Images