Abstract:
A method for fabricating a brightened composite shell includes step of (a): providing an uncured composite material on a surface of a metallic mold; step (b): curing the composite material by vacuum molding to form a consolidated composite embryo via the vacuum molding process; and step (c): machining the cured composite embryo so as to fabricate the final brightened shell shape. The present invention employs non-painting method and provides a brightened composite shell having a smooth and stereo surface without blisters and pin-holes being generated thereon.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a brightened composite shell and a method for fabricating the same without blisters and pin-holes.  
       BACKGROUND OF THE INVENTION  
       [0002]     Products with a hard casing are used in a multiple variety of fields such as the case of computers, cellular phones, laptops, or suitcases. Generally, the hard cases can be made by plastic or metallic material such as Aluminum alloy or Magnesium alloy. The plastic casing can be made by way of injection molding and in order to obtain a thin and sophisticate casing, a more complicated method is developed to inject the plastic material. However, the complicated method is costly and the thin plastic casing has less structural strength so that it is easily to be broken.  
         [0003]     The metallic casings are heavy and involve high-cost molds. Both of the plastic and metallic casings have to be coated with an outer protection layer to display its surface quality.  
         [0004]     Another method uses a method of press molding to laminate multiple layers of composite material and the products are light and have better structural strength. Nevertheless, the casing needs to be coated with a transparent resin to have a bright and smooth outer surface. Besides, there are blisters or pin-holes generated during the processes of the method so that extra careful steps are taken to remove these blisters and pin-holes.  
         [0005]     The present invention intends to provide a method for fabricating a brightened composite shell by way of vacuum molding and blisters and pin-holes are generated so that the products have stereo surfaces no generally coating processes.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention relates to a shell with a brightened surface and the shell is made by the following steps which are:  
         [0007]     step (a): providing an uncured composite material on a surface of a metallic mold, the composite material comprising lamination of pre-preg of matrix resin and fibers, a weight ratio of the matrix reins in the composite material being 30% to 60%;  
         [0008]     step (b): curing the composite material by vacuum molding to form a semi-product; and  
         [0009]     step (c): machining the cured composite semi-product by removing surplus material to become a final product.  
         [0010]     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a flow chart of the steps of the method of the present invention;  
         [0012]      FIG. 2  is a cross sectional view of the shell made by the method of the present invention;  
         [0013]      FIG. 3  is a part of a case of a computer made by the method of the present invention, and  
         [0014]      FIG. 4  shows different patterns or labels are used to decorate the shell of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]     Referring to  FIG. 1 , the method of the present invention comprises the following steps:  
         [0016]     a step  11  of providing an uncured composite material  11 ;  
         [0017]     a step  12  of providing a metallic mold;  
         [0018]     a step  13  of providing surface treatment to the metallic mold;  
         [0019]     a step  14  of providing the uncured composite, material  11  on the metallic mold;  
         [0020]     a step  15  of curing the composite material by vacuum molding to form a consolidated semi-product, and a step  16  of machining by removing surplus material to become a final product.  
         [0021]     The composite material can be one of a carbon-fiber composite material, a KEVLAR fiber composite material, a glass-fiber composite material, a dyed-fiber composite material and a hybrid-fiber composite material.  
         [0022]     The composite material includes multiple laminations of pre-preg of matrix resin and fibers, a weight ratio of the matrix reins in the composite material being 30% to 60%. The contents of the matrix resin is one or two times of general pre-preg material. The matrix resin of the composite material is chosen from one of a thermosetting resin and a thermoplastic resin. The way of weaving of the fibers can be one of a unidirectional weave, a plain weave, a satin weave, a twill weave and a multi-axial weave.  
         [0023]     The composite material is cut into proper sizes before being put on the metallic mold and the composite material and the metallic mold are sealed by using a sealing member.  
         [0024]     The metallic mold is treated by a surface treatment to obtain a polished mold with a fine and smooth surface. The surface treatment includes a surface polish process and a surface hardening process. The surface polish process is one of the following methods which are mechanical polishing, chemical polishing, chemical-mechanical polishing (CMP). The surface hardening process can be one of the following treatments which are a surface chrome coating process, a surface titanium coating process, a surface carburizing process and a surface nitrogenzing process. The uncured composite material is then put on the metallic surface that is treated.  
         [0025]     The vacuum molding is done by a vacuum appliance which can be one of the following devices which are an autoclave, an oven and a pump. The vacuum molding is to seal the composite material by using a seal member and the composite material is heated in a temperature between 0 to 1600 degrees Celsius under a pressure between 0 to 100 atmospheric pressure.  
         [0026]     As shown in  FIG. 2 , the metallic mold  21  used with the vacuum appliance  2  is polished to have a fine and smooth surface and the treatment can be a surface chrome coating process, a surface titanium coating process, a surface carburizing process or a surface nitrogenizing process. A releasing agent is applied to the surface of the metallic mold  21  so as to easily separate the semi-product and the mold.  
         [0027]     The composite material  22  is then laminated on the metallic mold  21  at a proper angle. A seal member  23  is used to seal the metallic mold  21  and the composite material  22 , and the sealed pack is sent to the vacuum appliance  2  to check the reliability of the sealing by the seal member  23 .  
         [0028]     The sealed pack of the composite material  22  is then laminated on the metallic mold  21  is sent into an oven or an autoclave to cure or consolidate. By proper setting of the temperature and pressure, the seal member  23  is removed and the semi-product is then machined to remove the surplus material to form the final product which has a brightened surface.  
         [0029]     As shown in  FIG. 3 , the shell made by the method of the present invention uses three to five layers of plain weave carbon fiber fabric or multiple layers of satin weave of KEVELAR/Epoxy pre-preg  31 . The pre-preg  31  is cured by using an autoclave. The composite material for making computer casings  3  is heated at 110 to 150 degrees Celsius under 2 to 20 atmospheric pressure. The composite material includes high ratio of resin so that the pre-preg  31  is cured on the metallic mold  21  and forms a bright surface  310  which is directly formed by the reins so that no painting or coating is needed. Due to the vacuum treatment and high pressure, there are no blisters and pin-holes generated, and the bright surface  310  has stereo surface which meets requirement for the casing of laptops in the market.  
         [0030]     As shown in  FIG. 4 , another embodiment uses multiple layers of prepreg and different patterns or labels  4  are put in the final products. The composite material for making electronic appliance casings is heated at 110 to 150 degrees Celsius for two hours. The final products have a bright surface and no painting or coating is needed. There are no blisters and pin-holes generated, and the bright surface  310  has stereo surface which meets requirement for the casing of laptops in the market.  
         [0031]     As shown in  FIG. 3 , the patterns or labels  5  are put in the metallic mold and laminated with the composite material. The patterns or labels  5  is in a form of prepreg resin and the surfaces of the patterns or labels  5  are combined with the surfaces of the prepreg  31  so a to form a bright surface  3   10 . The patterns or labels  5  can be made by plastic material or metallic material, and the resin of the composite material flows to an outer surface of the patterns or labels  5  to form the bright surface.  
         [0032]     While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.