METALLIC COVER
A metallic cover includes a bottom base and four side walls perpendicularly extending from a periphery of the rectangular bottom base. The four side walls cooperatively define a cavity together with the rectangular bottom base. The bottom base and each of the side walls of the metallic cover are correspondingly connected at an edge. The side walls of the metallic cover are formed by cold forging, thus a thickness of each of the side walls of the metallic cover is greater than that of the bottom base.
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The present application is a divisional application of U.S. patent application Ser. No. 12/012,298, filed on Feb. 1, 2008.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention generally relates to metallic covers, and more particularly to a metallic cover used for electronic devices and a method for making the metallic cover.
2. Discussion of the Related Art
Generally, a metallic cover has a more appealing appearance and a better surface feel than a plastic cover, thus metallic covers are popularly used for electronic devices such as mobile phones.
Referring to
Each of the side walls 12, 13, 14, 15 and the bottom base 11 are connected at an edge (not labeled). The edge is generally a rounded edge so that the metallic cover 10 can easily be made by metal drawing method.
However, in order to obtain a different appearance, an edge of another typical cover for connecting the side walls and the bottom base may be a beveled edge instead of the rounded edge. Generally, it is practically impossible to produce the beveled edge using the metal drawing method. A typical method for making a metallic cover with a beveled edge includes two following steps: drawing a metal sheet into a preformed cover; pressing the preformed cover into a metallic cover with a beveled edge by a forming die. However, the edges of the metallic cover are prone to cracks, when using the above method, thus decreasing quality of the metallic covers.
In addition, in order to reduce the volume, size or weight of these electronic devices such as mobile phones, the described metallic covers are generally made by thin metal sheet. However, a thickness of the side walls of the metallic covers is the same as that of the bottom base of the metallic covers. As a result, the strength of the side walls of the metallic covers is relatively low. To enhance the strength of the side walls of a metallic cover, a thickness of each side wall of the metallic cover should be greater than that of the bottom base of the metallic cover. It is also practically impossible to produce an unequal-thickness metallic cover using the metal drawing method. The unequal-thickness metallic cover is generally made by a die-casting method. However, the appearance of the unequal-thickness metallic cover made by the die-casting method is not good, thus the unequal-thickness metallic cover needs to be polished to improve the quality of the appearance of the unequal-thickness metallic cover.
At present, unequal-thickness metallic covers can also be manufactured by computerized numerical control (CNC) milling machines. A first typical method for making an unequal-thickness metallic cover will now be described. A relatively thick raw metallic block is provided. The raw metallic block has to go through several milling processes so as to get a preformed body. The preformed body is made into a metallic cover by a process of finish machining. The above method for making unequal-thickness metallic covers takes a great deal of time, for example, it needs more than ten hours for a process to make one unequal-thickness metallic cover of a mobile phone. Because the unequal-thickness metallic cover goes through several milling processes, the efficiency of the described method is low, thereby increasing the cost of the unequal-thickness metallic covers.
Referring to
Therefore, a new metallic cover is desired in order to overcome the above described shortcomings. A new method having high efficiency for making such metallic cover is also needed.
SUMMARYIn one aspect, a metallic cover includes a bottom base and a side wall extending from the bottom base. The side wall is formed by cold forging so that a thickness of the side wall is greater than that of the bottom base.
In another aspect, a method for making the metallic cover described above, includes: drawing a metallic sheet into a preformed cover having a bottom base and a plurality of side walls, and the bottom base and each of the sidewalls connected at a rounded edge; forging the preformed cover by a first forming die to thicken the side walls, and a first slanted pressing surface formed on an end of each of the side walls; forging the preformed cover by a second forming die to further thicken the side walls, and a second slanted pressing surface intersecting with the first slanted pressing surface formed on the end of each of the side walls, and the rounded edge of the preformed cover pressed into a beveled edge; and machining the end of each of the side walls of the preformed metallic cover so that the preformed metallic cover is made into the metallic cover.
Other novel features and advantages will become more apparent from the following detailed description, when taken in conjunction with the accompanying drawings.
The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating principles of the present metallic cover and method for making the same. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views, and all the views are schematic.
Reference will now be made to the drawings to describe preferred embodiments of the present metallic cover and method in detail.
Referring to
In the described embodiment, b represents a thickness of the bottom base 21, t represents a thickness of each of the side walls 22, 23, 24, 25, and h represents a height of each of the side walls 22, 23, 24, 25. The ratio between t and b (t/b) is preferably in a range from about 1 to about 3, and the ratio between h and b (h/b) is preferably in a range from about 1 to about 2.5. The metallic cover 20 is preferably made of aluminum alloy. The edge 26 is a beveled edge formed by cold forging. The angle formed between an outer surface of the bottom base 21 and an outer surface of each of the sidewalls 22, 23, 24, 25 at the edge 26 is in a range from about 90 degrees to about 135 degrees.
It should be pointed out that, the bottom base 21 can also be other shapes such as triangular, pentagonal, and hexagonal. The edge 26 is not limited to a beveled edge, the edge can also be other shapes, that is, not beveled, formed by cold forging.
Referring to
Referring to
In the drawing process, a metallic sheet is drawn into a preformed metallic cover 30. In the illustrated embodiment, the metallic sheet used for making the preformed metallic cover 30 is preferably made of aluminum alloys such as 5052-O aluminum alloy. The preformed cover 30 includes a bottom base 31 and a plurality of side walls 32. The side walls 32 cooperatively define a cavity (not labeled) for receiving electronic components (not shown). The bottom base 31 and each of the sidewalls 32 are connected at a rounded edge 33.
In the first cold forging process, the preformed cover 30 is forged by a first forming die 200 to flatten the side walls 32, thereby thickening (widening) the side walls 32, and to form a first slanted pressed surface 321 (see
Referring to
The punch 240 includes a punching portion 2401 and a restricting portion 2402 that connects to the punching portion 2401. The punching portion 2401 includes a first side surface 2404, a second side surface 2405, and a slanted working surface 2406. The first side surface 2404 is parallel to the second side surface 2405, and the first side surface 2404 and the second side surface 2405 are on opposite sides of the punching portion 2401 correspondingly. d1 represents a distance between the first side surface 2404 and the second side surface 2405, and t represents the final thickness of the sidewall of the metallic cover. The distance d1 should be in a range from 0.7 t to 0.9 t. The distance d1 is preferably in a range from 0.8 t to 0.85 t. An edge of the slanted working surface 2406 connects the first side surface 2404 and an opposite edge of the slanted working surface 2406 connects the second side surface 2405. The edge of the slanted working surface 2406 adjacent to the first side surface 2404 is configured to be higher than the opposite edge of the slanted working surface 2406 adjacent to the second side surface 2405. In other words, the slanted working surface 2406 slants towards the first side surface 2404. An angle β1 defined by the slanted working surface 2406 relative to the first side surface 2404 should be in a range from about 45 degrees to about 70 degrees. The angle β1 is preferably in a range from about 60 degrees to about 65 degrees. The restricting portion 2402 includes a positioning surface 2403 for restricting the motion range of the pressing member 230.
Before the first cold forging process, a distance between the upper surface 2302 of the pressing member 230 and the mounting surface 2201 of the lower die 220 is greater than the thickness of the bottom base 31 of the preformed metallic cover 30. The pressing surface 2304 of the extending portion 2303 of the pressing member 230 abuts the second side surface 2405 of the punching portion 2401 of the punch 240. The side surface 2301 of the pressing member 230 abuts the restricting portion 2402 of the punch 240. A lower end of the extending portion 2303 of the pressing member 230 is set a predetermined distance away from the positioning surface 2403 of the restricting portion 2402 of the punch 240. The preformed metallic cover 30 is placed on the lower die 220 and the side walls 32 of the preformed metallic cover are received in the molding groove 270.
During the first cold forging process, the upper surface 2302 of the pressing member 230 and the bottom base 31 of the preformed metallic cover 30 are pressed by the upper die 210. When the lower die 220 and the pressing member 230 are pressed, the first resilient member 250 and the second resilient member 260 becomes compressed. When the lower die 220 and the pressing member 230 are pressed, the side walls 32 of the preformed metallic cover 30 received in the molding groove 270 presses/pushes against the slanted working surface 2406 of the punch 240; material of the side walls 32 displaces (molds) into the molding groove 270. When the pressing member 230 is pressed until the extending portion 2303 of the pressing member 230 abuts the positioning surface 2403 of the restricting portion 2402 of the punch 240, the lower die 220 and the pressing member 230 stop moving. In the first cold forging process, material of the side walls 32 of the preformed metallic cover 30 flattens out into the molding groove 270, thus the side walls 32 of the preformed metallic cover 30 become thicker (wider) than the bottom base 31. The rounded edge 33 of the preformed cover 30 is pressed into a substantially beveled edge.
In the second cold forging process, the preformed cover 30 is forged by a second forming die 300 to flatten the side walls 32, thereby further thickening (widening) the side walls 32, and to form a second slanted pressing surface 322 intersecting with the first slanted pressing surface 321 on the end of each of the side walls 32. The rounded edge 33 of the preformed cover 30 is pressed into the beveled edge 26.
Referring to
The punch 340 includes a punching portion 3401 and a restricting portion 3402 connecting to the punching portion 3401. The punching portion 3401 includes a first side surface 3404, a second side surface 3405, and a slanted working surface 3406. The first side surface 3404 is parallel to the second side surface 3405, first side surface 3404 and the second side surface 3405 are on opposite sides of the punching portion 3401 correspondingly. A distance d2 between the first side surface 3404 and the second side surface 3405 equals to the thickness t of the sidewall of the metallic cover to be formed. An edge of the slanted working surface 3406 connects the first side surface 3404 and an opposite edge of the slanted working surface 3406 connects the second side surface 3405. The opposite edge of the slanted working surface 3406 adjacent to the second side surface 3405 is configured to be higher than the edge of the slanted working surface 3406 adjacent to the first side surface 3404. An angle β2 defined by the slanted working surface 3406 relative to the first side surface 3404 should be in a range from about 45 degrees to about 70 degrees. The angle β2 is preferably in a range from about 60 degrees to about 65 degrees. The restricting portion 3402 includes a positioning surface 3403 for restricting the motion range of the pressing member 330. The punch 340, the lower die 320, and the pressing member 330 cooperatively define a molding groove 370 for receiving the side walls 32 of the preformed metallic cover 30. A thickness of the molding groove 370 is greater than the thickness of the side walls 32 of the preformed metallic cover 30.
In the second cold forging process, the pressing member 330 and the bottom base 31 of the preformed metallic cover 30 is pressed by the upper die 310. When the lower die 320 and the pressing member 330 are pressed, the side walls 32 of the preformed metallic cover 30 received in the molding groove 370 presses/pushes against the slanted working surface 3406 of the punch 340; material of the side walls 32 displaces (molds) into the molding groove 370. When the extending portion 3303 of the pressing member 230 abuts the positioning surface 3403 of the restricting portion 3402 of the punch 340, the lower die 320 and the pressing member 330 stop moving. In the second cold forging process, material of the side walls 32 of the preformed metallic cover 30 flattens out into the molding groove 370, thus the side walls 32 of the preformed metallic cover 30 become thicker than the bottom base 31 and the rounded edge 33 of the preformed cover 30 is pressed into beveled edge.
In the finish machining process, each of the side walls 32 of the preformed metallic cover 30 is machined to a predetermined shape by a machining tool such as a milling machine, and thereby forming the metallic cover 20. In the described embodiment, the first slanted pressing surface 321 and the second slanted pressing surface 322 of each of the side walls 32 are cut off and a flat surface is formed on the side walls 32.
In an alternative embodiment, referring to
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.
Claims
1. A metallic cover, comprising:
- a bottom base; and
- at least one side wall extending from the bottom base;
- wherein the at least one side wall is formed by cold forging so that a thickness of the at least one side wall is greater than that of the bottom base.
2. The metallic cover as claimed in claim 1, wherein the bottom base and the at least one side wall are connected at an edge, and the edge is a beveled edge.
3. The metallic cover as claimed in claim 2, wherein an angle defined by an outer surface of the bottom base relative to the at least one sidewall at the edge is in a range from 90 degrees to 135 degrees.
4. The metallic cover as claimed in claim 2, wherein the metallic cover is made of aluminum alloy.
5. The metallic cover as claimed in claim 1, wherein a ratio of a thickness of the at least one side wall with respect to a thickness of the bottom base is in a range from 1 to 3, and a ratio of a height of the at least one side wall with respect to the thickness of the bottom base is in a range from 1 to 2.5.
6. The metallic cover as claimed in claim 1, wherein the bottom base is rectangular, the metallic cover comprises four side walls, and the side walls perpendicularly extend from a periphery of the rectangular bottom base.
7. The metallic cover as claimed in claim 6, wherein the bottom base and each of the side walls are connected at an edge, and the edge is a beveled edge.
8. The metallic cover as claimed in claim 7, wherein the metallic cover is made of aluminum alloy, and an angle defined by an outer surface of the bottom base relative to the sidewalls at the edge is in a range from 90 degrees to 135 degrees.
9. The metallic cover as claimed in claim 8, wherein a ratio of a thickness of the side walls with respect to a thickness of the bottom base is in a range from 1 to 3, and a ratio of a height of the side walls with respect to the thickness of the bottom base is in a range from 1 to 2.5.
10. A metallic cover, comprising:
- a rectangular bottom base; and
- four side walls perpendicularly extending from a periphery of the rectangular bottom base, and cooperatively defining a cavity together with the rectangular bottom base;
- wherein the bottom base and each of the side walls of the metallic cover are correspondingly connected at an edge, and the side walls of the metallic cover are formed by cold forging, thus a thickness of each of the side walls of the metallic cover is greater than that of the bottom base.
11. The metallic cover as claimed in claim 1, wherein a ratio of a thickness of each of the side walls with respect to a thickness of the bottom base is in a range from 1 to 3, and a ratio of a height of each of the side walls with respect to the thickness of the bottom base is in a range from 1 to 2.5.
12. The metallic cover as claimed in claim 12, wherein the metallic cover is made of aluminum alloy, and the edge is a beveled edge formed by cold forging.
13. The metallic cover as claimed in claim 13, wherein an angle defined by an outer surface of the bottom base relative to the sidewalls at the edge is in a range from 90 degrees to 135 degrees.
Type: Application
Filed: Aug 23, 2011
Publication Date: Dec 15, 2011
Applicants: HON HAI PRECISION INDUSTRY CO., LTD. (Tu-Cheng), HONG FU JIN PRECISION INDUSTRY (ShenZhen) CO., LTD (Shenzhen City)
Inventor: BAO-PING SU (Shenzhen City)
Application Number: 13/215,360
International Classification: B65D 8/04 (20060101);