Abstract:
A method of manufacturing a metal shield of an electrical connector comprises following steps: (a) stamping step to stamp a metal carrier continuously to form a framework having an underside and sidewall; (b) cutting step to cut the underside of the framework out and form a thin edge at the bottom of the sidewall; (c) trimming step to prune the thin edge of sidewall; (d) shaping step to stamp the framework continuously with a punch having chamfers.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention is generally related to a metal shield of an electrical connector and method of manufacturing, and more particular to a metal shield having continuous bent edge of an electrical connector and method of manufacturing.  
           [0003]    2. Description of the Related Art  
           [0004]    Port connector is a sort of necessary apparatus in transmitting signals between a computer and a peripheral apparatus. Familiar port connectors include D-shaped connectors between mainframe and a monitor of a computer, USB (Universal Serial Bus) connectors between the mainframe and a keyboard or a mouse of a computer, and IEEE 1394 (a standard established by Institute of Electrical &amp; Electronic Engineers) connectors. In order to receive a mating plug in and provide shielding and grounding effect to ensure transmission of signals therebetween, the foregoing port connector generally has a metal exterior shield as a common characteristic. There are two known methods of manufacturing the metal shield of the electrical connector. First method is to stamping a flat rectangular piece continuously and join two edges together to produce a metal framework having a sidewall, wherein bottom edge of the framework is bent outwardly at a given angle to guide a mating plug. Most shields of conventional USB connectors made by the foregoing method are typically shown in FIG. 7. However, when the two bottoms are transfigured or shifted appreciably, rectangular shape of the shield will be damaged. In addition, bent edges  42  of metal shield  4  as shown in FIG. 7 have to be formed at bottom edges  41  but not at the corners  43  because of limitation of existing technique. The only way to revolve this is to cut the edge at the corners instead of forming bent edges, but it will affect appearance of the whole electrical connector.  
           [0005]    Second method of manufacturing a shield is to stamping plat piece to form a rectangular framework having continuous edges from a flat carrier as shown in FIG. 8. Many connectors such as D-shaped connector, micro IEEE 1394 connector are commonly made by this approach. Referring to FIG. 8, an electrical connector having a metal shield  5  manufactured by this method is shown. It is inevitable that corners  51  of continuous edge of the shield  5  will split as shown in FIG. 8 while being bent outwardly. In addition, users are likely to be hurt by burred edges of the corners, and it will affect appearance of the electrical connector too.  
           [0006]    Hence, an improved metal shield of electrical connector is required to overcome the disadvantages of the prior art.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    Therefore, an objective of the present invention is to provide an improved metal shield of an electrical connector which has a continuous and smooth bent edge.  
           [0008]    Another objective of the present invention is to provide a method of manufacturing a metal shield of an electrical connector to obtain a continuous and smooth bent edge to guide a mating electrical connector.  
           [0009]    To achieve the above-mentioned objectives, in the method of the present invention, a metal shield having a continuous and smooth bent edge is produced by the following steps:  
           [0010]    (a) stamping step: stamping a metal carrier continuously to form a framework having an underside, a continuous sidewall and a vaulted portion therebetween, the vaulted portion has a radius equal to the thickness of the carrier formed at a bottom of the sidewall, the thin edge is thinner than the sidewall;  
           [0011]    (b) cutting step: cut the underside of the framework off that produced during the stamping step and form a thin edge at a bottom of the sidewall;  
           [0012]    (c) trimming step: trim the thin edge of sidewall by a length equal to the radius of the vaulted portion and burrs generated while trimming the thin edge away, thereby the sidewall has equal thickness and a smooth section; and  
           [0013]    (d) shaping step: bending the bottom of the sidewall to from at an angle of 120˜170 degrees with respect to the sidewall.  
           [0014]    According to another embodiment of the present invention, the foregoing stamping step further includes a first step to provide a suitable carrier to form the framework and a second step to stamping the carrier obtained via the first step with gradual changed punches to form a framework which has an underside and a continuous sidewall.  
           [0015]    Metal shield manufactured by above-mentioned steps includes a continuous sidewall and a bugle-like portion, wherein the sidewall covers an insulative housing of the electrical connector and the bugle-shaped edge is to guide a mating electrical connector.  
           [0016]    Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    The present invention is further described with reference to the accompanying drawings in which:  
         [0018]    [0018]FIG. 1 is a flow chart of manufacturing process in accordance with the present invention to manufacture a shield of an electrical connector;  
         [0019]    [0019]FIG. 2 is a partial cross sectional view of the shield after stamping step;  
         [0020]    [0020]FIG. 3 is a partial cross sectional view of the shield after cutting step;  
         [0021]    [0021]FIG. 4 is a partial cross sectional view of the shield after trimming step;  
         [0022]    [0022]FIG. 5 is a partial cross sectional view of the shield after shaping step;  
         [0023]    [0023]FIG. 6 is a perspective view of an electrical connector manufactured by the method in accordance with the present invention;  
         [0024]    [0024]FIG. 7 is a perspective view of a shield of an USB connector manufactured by one conventional method; and  
         [0025]    [0025]FIG. 8 is a perspective view of a shield of an electrical connector manufactured by another conventional method.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    Referring to FIG. 1, a method of manufacturing a metal shield of an electrical connector includes a stamping step, a cutting step, a trimming step, and a shaping step.  
         [0027]    The stamping step further includes a first step and a second step. The first step is to cut down a suitable piece from a metal carrier to form a framework of the metal shield. In this embodiment, taking the metal shield of a micro IEEE 1394 connector (referring to FIG. 6) as an example, dimensions of a suitable piece obtained from the carrier are 24*12 mm. While profile of a framework of the shield is about an isosceles trapezoid and the piece will have a distortion due to being stamped, the suitable piece should be large enough to fulfill extending of the carrier. The suitable piece has four connecting arms at corners thereof to connect with the carrier.  
         [0028]    The second step is stamping the carrier 1′ continuously with a series of punches till a framework  20 ′ of the metal shield is formed. Referring to FIG. 2, the framework  20 ′ has an underside  26 ′, a continuous sidewall  22 ′ and a vaulted portion of a radius r therebetween.  
         [0029]    The underside  26 ′ is then cut off from the framework  20 ′ by a punch having a knife-edge to obtain a hollow metal shield as shown in FIG. 3. According to teaching of general knowledge of mechanics, the vaulted portion must have the biggest strain in the carrier  20 ′. By the way, a thin edge is formed at a bottom of the sidewall  22 ′ much thinner than the sidewall  22 ′. After the underside  26 ′ being cut as shown in amplificatory view in FIG. 3, it is inevitable that corners of the framework  20 ′ will split if edges of the sidewall  22 ′ is bent directly. Therefore, a trimming step is necessary to be put up before the shaping step.  
         [0030]    Trimming step is to trim the thin edge adjacent to the sidewall  22 ′ of the above-mentioned framework  20 ′ and wipe off burrs generated during the cutting step, thereby the sidewall  22  has equal thickness and smooth section. In the trimming step, the thin edge is ground firstly, however it can be embodied with other means, e.g. cutting. Length of the edge portion cut from the sidewall must be larger than thickness of the carrier  20 ′. In theory, perfect length of the thin edge cut off from the sidewall is equal to the thickness of the carrier  20 ′, but in actual operation, there will be a distortion which makes the thin edge longer than r. Referring to FIG. 4, the framework  20 ′ obtained by above-mentioned steps has uniform thickness. Also, cross-section of the framework is smooth which facilitates the shaping step.  
         [0031]    A shaping step stamps the framework  20 ′ obtained by above steps continuously with a series of punches having campers (not shown) till bottom of the sidewall  22 ′ forms a bugle shape. In the present embodiment, a module (not shown) is received in the framework  20 ′ and a metal ringer (not shown) is placed at the outer surface. By this arrangement, portions of the framework  20 ′ except for the edge will be prevented from being deformed and improper distortion will be corrected. In the shaping step, the edge will be bent 120˜175 degrees against the sidewall  22 ′. In the present embodiment, 150˜160 degrees is preferred (FIG. 5). It is to be noticed that elongation rate δ must be taken account of to ascertain length of the edge to be bend and angle between the edge and the sidewall  22 ′. Assume the perimeter of the framework  20 ′ is L1 before the shaping step and is L2 after the shaping step, then,  
         δ=(L2−L1)/L1  
         [0032]    The elongation rate  5  less than 50% is preferred in practice. Of course, the δ may be amplified if the metal carrier  2 ′ to manufacture the framework  20 ′ has an apt elongation rate.  
         [0033]    In the present embodiment, suitable steps are employed to stamp a shield portion of a pair of wings  10  as shown in FIG. 8 and to punch a hole  12  and a barb  14  on each of the wings  10  to assemble with an insulative housing of the electrical connector (not shown). Thus, a usable metal shield is completed.  
         [0034]    Referring to FIG. 8, a metal shield obtained by above mentioned manufacturing steps includes a pair of wings  10  and a framework  20  integrally formed with the wings  10 , wherein the wings  10  are assembled with an insulative housing to shield the housing and the framework  20  surrounds terminals of the electrical connector to provide a space to receive a mating connector (not shown). The framework  20  has a continuous bent edge  24  to form a bugle shape. A hole  12  and a barb  14  are defined on each wing  10  to assemble with the insulative housing firmly. Because the framework  20  has continuous bent edge  24  and smooth section, the electrical connector has an improved shielding effect and attribute and a better appearance.  
         [0035]    It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.