Patent Abstract:
A method for making a metallic casing includes providing an apparatus comprising a first mold and a second mold, placing a preform into a rectangular depression of first mold, moving the first mold to the second mold so that each sharp edge is substantially coplanar with a corresponding cutting edge, moving the first mold to the second mold so that the cutting edges are beyond the corresponding sharp edges of the first mold to complete a partial cut procedure, and moving the first mold to the second mold so that the secondary-cutting edge moves beyond the corresponding sharp edge and completely cuts the excess off the side wall.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a divisional application of U.S. patent application Ser. No. 11/944,464, filed on Nov. 23, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a method and an apparatus for making a metallic casing, particularly, for making a metallic casing used in portable electronic devices. 
     2. Discussion of the Related Art 
     Metallic casings are considered attractive candidates for use in various portable electronic devices such as an MP3 player, personal digital assistance (PDA), and mobile phone because of their sturdiness and appealing appearance. 
     Referring to  FIG. 6 , a typical metallic casing  10   a  includes an approximately rectangular base  11   a , a first sidewall  12   a , a second sidewall  13   a , a third sidewall  14   a , and a fourth sidewall  15   a . The first sidewall  12   a , the second sidewall  13   a , the third sidewall  14   a , and the fourth sidewall  15   a  all extend around a periphery of the base  11   a . The first sidewall  12   a , the second sidewall  13   a , the third sidewall  14   a , and the fourth sidewall  15   a  respectively connect to each other. The first sidewall  12   a , the second sidewall  13   a , the third sidewall  14   a , the fourth sidewall  15   a , and the base  11   a  cooperatively define a cavity (not labeled) with an opening. The cavity is configured for receiving electronic components. 
     The metallic casing  10   a  is made from a preform  10   b  (shown in  FIG. 7 ). The preform  10   b  is made from a metal plate by a drawing process. The preform  10   b  includes an approximately rectangular base  11   b , a first sidewall  12   b , a second sidewall  13   b , a third sidewall  14   b , and a fourth sidewall  15   b . The first sidewall  12   b , the second sidewall  13   b , the third sidewall  14   b , and the fourth sidewall  15   b  all extend around a periphery of the base  11   b . The first sidewall  12   b , the second sidewall  13   b , the third sidewall  14   b , and the fourth sidewall  15   b  respectively connect to each other. The first sidewall  12   b , the second sidewall  13   b , the third sidewall  14   b , the fourth sidewall  15   b , and the base  11   b  cooperatively define a cavity with an opening. An end of each of the first sidewall  12   b , the second sidewall  13   b , the third sidewall  14   b , and the fourth sidewall  15   b  bends outward and respectively forms a first excess  121   b , a second excess  131   b , a third excess  141   b , and a fourth excess  151   b . The first excess  121   b , the second excess  131   b , the third excess  141   b , and the fourth excess  151   b  respectively connect to each other. Each of the first excess  121   b , the second excess  131   b , the third excess  141   b , the fourth excess  151   b , and the base  11   b  form a corresponding connecting portion  122   b ,  132   b ,  142   b , and  152   b . In other words, the preform  10   b  includes an article portion and an excess portion. The article portion of the preform  10   b  consists of the base  11   b  and the sidewalls  12   b ,  13   b ,  14   b ,  15   b . The excess portion of the preform  10   b  consists of the excesses  121   b ,  131   b ,  141   b ,  151   b.    
     Also referring to  FIG. 8 , an apparatus  100  includes an upper mold  110 , a lower mold  130 , and a positioning member  150 . The upper mold  110  is opposite to the lower mold  130 , and the upper mold  110  is movable relative to the lower mold  130 . The upper mold  110  defines a rectangular depression (not labeled) opposite to the lower mold  130 . The rectangular depression forms a first side surface  112 , a second side surface  113 , a third side surface  114 , and a fourth side surface  115 . The first side surface  112 , the second side surface  113 , the third side surface  114 , and the fourth side surface  115  respectively connect to each other. The side surface  112 ,  113 ,  114 , and  115  respectively forms a first sharp edge  1121 , a second sharp edge  1131 , a third sharp edge  1141 , and a fourth sharp edge  1151 . The first sharp edge  1121 , the second sharp edge  1131 , the third sharp edge  1141 , and the fourth sharp edge  1151  respectively connect to each other. The lower mold  130  includes cutting side  131 . The cutting side  131  includes a first cutting edge  132 , a second cutting edge  133 , a third cutting edge  134 , and a fourth cutting edge  135 . The first cutting edge  132 , the second cutting edge  133 , the third cutting edge  134 , and the fourth cutting edge  135  correspond to the first sharp edge  1121 , the second sharp edge  1131 , the third sharp edge  1141 , and the fourth sharp edge  1151 , respectively. A horizontal width of the first cutting edge  132  is substantially equal to that of the first sharp edge  1121 . A horizontal width of the second cutting edge  133  is substantially equal to that of the second sharp edge  1131 . A horizontal width of the third cutting edge  134  is substantially equal to that of the third sharp edge  1141 . A horizontal width of the fourth cutting edge  135  is substantially equal to that of the fourth sharp edge  1151 . 
     In a process of making the metallic casing  10   a  shown in  FIG. 6 , the preform  10   b  is placed into the rectangular depression of the upper mold  110 . The connecting portions  122   b ,  132   b ,  142   b ,  152   b  are located at the cutting edges  1121 ,  1131 ,  1141 ,  1151  respectively. The positioning member  150  is placed into the cavity of the preform  10   b  so that the preform  10   b  is fixed in the rectangular depression of the upper mold  110 . 
     The upper mold  110  moves vertically to the lower mold  130  to keep the first sharp edge  1121 , the second sharp edge  1131 , the third sharp edge  1141 , and the fourth sharp edge  1151  substantially coplanar with the first cutting edge  132 , the second cutting edge  133 , the third cutting edge  134 , and the fourth cutting edge  135 , respectively. The lower mold  130  moves horizontally in a first direction at a predetermined distance such that the first cutting edge  132  moves beyond the first sharp edge  1121 . Thus, the first excess  121   b  is sliced from the first sidewall  12   b . Similarly, the lower mold  130  moves horizontally in a second, third, and fourth direction at a predetermined distance in that order, such that the second cutting edge  133 , the third cutting edge  134 , and the fourth cutting edge  135  moves beyond the second sharp edge  1131 , the third sharp edge  1141 , and the fourth sharp edge  1151 . Thus the second excess  131   b , the third excess  141   b , and the fourth excess  15  lb are sliced from the second sidewall  13   b , the third sidewall  14   b , and the fourth sidewall  15   b , respectively. The rotary cutting process is completed, thereby yielding an article  10   c  (shown in  FIG. 9 ). After that, the first sidewall  12   b  defines a slot  123  for receiving electronic components such as a connector. Thus, a metallic casing  10   a  is formed. 
     In a process of making the metallic casing  10   a , the first excess  121   b , the second excess  131   b , the third excess  141   b , and the fourth excess  151   b  respectively connect to each other. After the first excess  121   b , the second excess  131   b , and the third excess  141   b  are sliced from the preform  10   b , the excess portion of the preform  10   b  is not separated from the preform  10   b  completely because the fourth excess  151   b  of the excess portion is still connected with the fourth sidewall  15 . When the fourth excess  151   b  is sliced from the preform  10   b , the excess portion of the preform  10   b  is separated from the preform  10   b  completely. The location where the excess portion is completely separated from the preform  10   b  is at a boundary between the first sidewall  12   b  and the fourth sidewall  15   b . The excess portion of the preform  10   b  moves together with the lower mold  130  at the moment that the fourth excess  151   b  separates from the preform  10   b , thereby generating a tearing effect to the boundary between the first sidewall  12   b  and the fourth sidewall  15   b . Hence, after the rotary cutting process is completed, a gap  16   b  is formed at the top edge of the boundary between the first sidewall  12   b  and the fourth sidewall  15   b . The gap  16   b  makes a case made from the preform  10   b  having poor appearance. Thus an extra process, such as polishing, is required to remove the gap  16   b.    
     Therefore, a new method and apparatus is desired in order to overcome the above-described shortcomings. 
     SUMMARY 
     An apparatus for use in making a metallic casing includes a first mold and a second mold. The first mold is opposite and movable relative to the second mold. The first mold defines a rectangular depression opposite to the second mold. The rectangular depression forms a plurality of side surfaces connected to each other respectively. Each side surface has a sharp edge. The second mold includes a plurality of cutting edges corresponding to the sharp edges respectively and one of the cutting edges has a secondary-cutting edge. 
     Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present method and apparatus for making a metallic casing. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is an exploded, isometric view of an apparatus in accordance with one embodiment of the present disclosure. 
         FIG. 2  is an isometric view of a preform needed to be processed by the apparatus shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the apparatus shown in  FIG. 1  when processing the preform of  FIG. 2 . 
         FIG. 4  is an isometric view of an article made from the preform of  FIG. 2 . 
         FIG. 5  is an isometric view of a metallic casing made from the preform of  FIG. 4 . 
         FIG. 6  is an exploded, isometric view of a related metallic casing. 
         FIG. 7  is an exploded, isometric view of a related preform. 
         FIG. 8  is an isometric view of a related apparatus used for processing the preform of  FIG. 7 . 
         FIG. 9  is an isometric view of a related article made from the preform of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present apparatus is used for making metallic casings. Any kind of metal or alloy can be used as a material of the casing. In one embodiment, aluminum alloy is the material used in the apparatus for making the metallic casing. 
     Referring the  FIG. 1 , an apparatus  200  for making a metallic casing includes an upper mold  210 , a lower mold  230 , and a positioning member  250 . The positioning member  250  is a substantially flat plate. The upper mold  210  and the lower mold  230  are on opposite sides of the positioning member. The upper mold  210  is movable relative to the lower mold  230 . The upper mold  210  defines a rectangular depression opposite to the lower mold  230 . The rectangular depression forms a first side surface  212 , a second side surface  213 , a third side surface  214 , and a fourth side surface  215 . The first side surface  212 , the second side surface  213 , the third side surface  214 , and the fourth side surface  215 , respectively connect to each other. The first side surface  212 , the second side surface  213 , the third side surface  214 , and the fourth side surface  215  respectively forms a first sharp edge  2121 , a second sharp edge  2131 , a third sharp edge  2141 , and a fourth sharp edge  2151 . The lower mold  230  has a cutting side  231 . The cutting side  231  includes a first cutting edge  232 , a second cutting edge  233 , a third cutting edge  234 , and a fourth cutting edge  235 . The first cutting edge  232  is adjoining to the fourth cutting edge  235 , and the first cutting edge  232  defines a cutout  2321  adjacent to the fourth cutting edge  235 . The cutout  2321  is a groove defined in the first cutting edge  232 , and the groove forms a sidewall  2322 . An edge of the sidewall  2322  forms an arcuate secondary-cutting edge  2323 . 
     Referring to  FIGS. 2 and 3 , the apparatus  200  is used for processing a preform  20   b  (shown in  FIG. 2 ) by a rotary cutting process, thereby yielding an article  20   c  (shown in  FIG. 4 ). The preform  20   b  is manufactured by a drawing process. The preform  20   b  includes an approximately rectangular base  21   b , a first sidewall  22   b , a second sidewall  23   b , a third sidewall  24   b , and a fourth sidewall  25   b . The first sidewall  22   b , the second sidewall  23   b , the third sidewall  24   b , and the fourth sidewall  25   b  all extend around a periphery of the base  21   b . The first sidewall  22   b , the second sidewall  23   b , the third sidewall  24   b , and the fourth sidewall  25   b , respectively connect to each other. Each end of the first sidewall  22   b , the second sidewall  23   b , the third sidewall  24   b , and the fourth sidewall  25   b  bends outwardly and respectively forms a first excess  221   b , a second excess  231   b , a third excess  241   b , and a fourth excess  25  lb. The first excess  221   b , the second excess  231   b , the third excess  241   b , and the fourth excess  251   b , respectively connect to each other. The excesses  221   b ,  231   b ,  241   b ,  251   b , and the sidewalls  22   b ,  23   b ,  24   b ,  25   b  form connecting portions  222   b ,  232   b ,  242   b ,  252   b , respectively. In other words, the preform  20   b  includes an article portion and an excess portion. The article portion consists of the base  21   b , the first sidewall  22   b , the second sidewall  23   b , the third sidewall  24   b , and the fourth sidewall  25   b . The excess portion consists of the first excess  221   b , the second excess  231   b , the third excess  241   b , and the fourth excess  251   b.    
     In the making process, the preform  20   b  is placed into the rectangular depression of the upper mold  210 . The connecting portion  222   b  between the first sidewall  22   b  and the first excess  221   b  is located adjacent to the first sharp edge  2121 . The connecting portion  232   b  between the second sidewall  23   b  and the second excess  231   b  is located at the second sharp edge  2131 . The connecting portion  242   b  between the third sidewall  24   b  and the third excess  241   b  is located at the third sharp edge  2141 . The connecting portion  252   b  between the fourth sidewall  25   b  and the fourth excess  251   b  is located at the fourth sharp edge  2151 . The positioning member  250  is placed into the cavity of the preform  20   b  so that the preform  20   b  is fixed in the rectangular depression of the upper mold  210 . 
     The upper mold  210  moves vertically against (toward) the lower mold  230  until the first sharp edge  2121 , the second sharp edge  2131 , the third sharp edge  2141 , and the fourth sharp edge  2151  are substantially coplanar with the first cutting edge  232 , the second cutting edge  233 , the third cutting edge  234 , and the fourth cutting edge  235 , respectively. 
     The lower mold  230  then moves horizontally in a first direction at a predetermined distance such that the first cutting edge  232  moves beyond the first sharp edge  2121 . As a result, the first excess  221   b  is sliced from the first sidewall  22   b . The first cutting edge  232  defines a cutout  2321  adjacent to the fourth cutting edge  235 , by controlling the predetermined distance, a portion of a connecting portion formed between the first excess  221   b  and the first sidewall  22   b  can be kept un-sliced (uncut/separated). In the preferred embodiment, the predetermined distance is a distance such that the cutout  2321  does not go beyond the first sharp edge  2121 , thus leaving an uncut portion. 
     The lower mold  230  then moves horizontally in a second, third, and fourth direction at a predetermined distance in that order, such that the second cutting edge  233 , the third cutting edge  234 , and the fourth cutting edge  235  moves beyond the second sharp edge  2131 , the third sharp edge  2141 , and the fourth sharp edge  2151 . Thus the second excess  231   b , the third excess  241   b , and the fourth excess  251   b  are sliced from the second sidewall  23   b , the third sidewall  24   b , and the fourth sidewall  25   b , respectively. A partial cut procedure is completed. 
     After the partial cut procedure, an uncut portion remains. The lower mold  230  then moves horizontally in the first direction at a greater distance than the first time such that the secondary-cutting edge  2323  moves beyond the first sharp edge  2121 . Thus the uncut portion is cut or sliced. A final cut procedure is completed. 
     After the final cut procedure, the first excess  221   b , the second excess  231   b , the third excess  241   b , and the fourth excess  251   b  are completely removed from the preform  20   b . That is, the excess portion is separated from the preform  20   b , and then the article portion of the preform  20   b  is extracted, yielding an article  20   c  (shown in  FIG. 4 ). 
     The position member  250  is separated from the top mold and the article  20   c  is removed out of the rectangular depression. Finally, a slot  223 , configured for receiving electronic components such as a connector, is defined in the first sidewall  22   b  of the article  20   c . Thus, a metallic casing  20  (shown in  FIG. 5 ) is formed. 
     In the above mentioned process, when the uncut portion is cut or sliced, a gap  26   b  is defined in the top edge of the first sidewall  22   b  because the uncut portion is a part of the first sidewall. In addition, the first sidewall  22  is generally required to define a slot  223  for receiving electronic components such as a connector, and the slot  223  can be defined at an area where the gap  26   b  is located. The gap  26   b  can then be eliminated when defining the slot  223 . In the preferred embodiment, the slot  223  can be defined by a side punching process with a mold. The appealing appearance is achieved without extra process. 
     The preform  20   b  may includes three sidewalls, five or more sidewalls. When the number of the cutting edges is equal to that of the edges and the sidewalls of the preform  20   b , the number of the cutting edges of the upper mold and the edges of the lower mold may increase or decrease correspondingly. In an alternative embodiment, the cutout may be defined in another location such as a middle portion of the first cutting edge or a portion of the second cutting edge. In another embodiment, the cutout may be an inclined plane, the shape of the secondary-cutting edge may be an ellipse, linear, or any other shape. 
     Depending on the embodiment, certain of the steps described may be removed, others may be added, and the sequence of steps may be altered. It is also to be understood that the description and the claims drawn to a method may include some indication in reference to certain steps. However, the indication used is only to be viewed for identification purposes and not as a suggestion as to an order for the steps. 
     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 application or sacrificing all of its material advantages, the examples hereinbefore described merely being embodiments of the application.

Technology Classification (CPC): 8