Abstract:
A premold body forms an assembly to receive male conductors for molding into a plug. The plug to be used with a female receptacle outlet such as for 120 volt AC current. The body firmly holds blades or blades and a ground pin. By using the premold support the assembly may be assembled automatically, saving time and money in cycle time. The assembly may then be simultaneously crimped to more than one wire. The assembly is more reliable holding the conductors against being dislodged or having wild strands, particularly when molded into an outlet plug. The assembly saves labor and material cost and provides greater reliability over the prior art.

Description:
This application is a continuation of application Ser. No. 08/517,083, filed Aug. 21, 1995, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION AND DESCRIPTION OF THE RELATED ART 
     The present invention is a molded plastic support usable as a premold for male contacts in an outlet plug. The support may be referred to as a bridge or male bridge since it holds male contacts in a spaced relationship. 
     Plugs for conventional 120 volt AC current electrical outlets usually include a pair of blades and a ground pin. The contacts are usually in a triangular relationship with a centered ground pin. In manufacture the blades and ground pin are usually crimped to individual conductor wires in a cable. 
     In the past wires for plugs were oftentimes machine crimped to contacts in automated systems. The wires of the cable were crimped, fed from a coil or roll on a stamping strip. The cord sets with wires crimped to the male blades and ground pin were then molded into plugs by being placed in a mold to be held in proper position. 
     Molding of plugs is complex. Three crimped male conductors have to be positioned in the mold for injection molding, it requires substantial labor, a substantial volume of plastic must be used in the molding and there is always the risk of wild strands. 
     By using the plastic support and assembly of the present invention, overmolding cycle time is reduced due to ease of loading the assembly into the mold. Overmolding compound requirement is reduced. 
     A less expensive overmolding compound can be used due to the plastic support retention characteristics. The plastic supports can be automatically assembled. 
     The plastic support allows for the crimping termination of all three contacts at once instead of the crimp termination of each of the blades and pin separately, in two different pieces of termination equipment. 
     The molding plastic, usually PVC, is a cost factor in the making of plugs. The labor of termination or crimping and engaging the crimped wire sets in a mold is expensive even though the crimping of the individual wires in the past was usually automated. 
     SUMMARY OF THE INVENTION 
     The present invention is a molded plastic support used in an assembly as a premold in which two flat metal male blades and/or one tubular metal male ground pin are engaged. This arrangement insures for the proper extension of the blades and/or ground pin from the front face of the plug in a molded cord set when over molded with PVC. The plastic support also provides for the proper spacing of the blades and/or a ground pin with regard to each other, both of which are specified by national standards associations. 
     The plastic support is cost effective because the overmolding cycle time is reduced due to ease of loading the plastic support into the mold, overmolding compound requirement is reduced, a less expensive overmolding compound can be used due to plastic support retention characteristics and plastic supports can be automatically (instead of hand) assembled. 
     The plastic support allows for the termination of all three contacts at once instead of terminating the blades and the pin separately in two different pieces of termination equipment. 
     The present invention does not have prior art problems associated with the contacts in molded plugs with high temperature, abrupt pull out and heavy weight testing, regardless of the molding compound used, as set up by national standards associations. The plastic support retains the contacts in the overmolded plastic cap rather than the contacts retaining themselves. 
     Blades and pins of the prior art which are overmolded without the plastic support of the present invention must be terminated separately, loaded into the production mold separately and have a greater risk of failure during testing particularly if a less expensive, softer durometer overmolding compound is used. 
     The plastic support of the present invention insures proper proper spacing of blades and/or a pin with regard to each other and to the pin and allows for automatic assembly where all (2 or 3) terminals are crimped at once. 
     The plastic support of the present invention is cost effective, reducing the cycle time required for overmolding, due to ease of engaging a loading plastic support into a mold and it reduces the plastic requirement regardless of the compound. 
     Once loaded with blades and/or pin terminations, automated crimping of wires from a cable to the plastic support may be done. 
     Basic advantages of the present invention are the speed and economy of assembly of the blades and/or pins in the plastic support, which is automatable, the ability to crimp cable wires to the male contacts in the plastic support, the ease of handling the assembly including the plastic support and the improved electrical integrity of a resulting molded plug. There is economic saving of molding plastic cost regardless of the compound used. 
     The present invention eliminates prior art individual crimping of wires and has the advantage of being more easily managed and saves the molding cost of the PVC plastic that is displaced by the plastic support. 
     Molding can be prepared in a shorter time, using less molding material. 
     According to the present invention, a premold assembly for a molded plastic electric outlet plug has male conductors to engage in openings in an electrical outlet female receptacle&#39;s usual spaced openings, for blades and a ground pin. The assembly has a molded plastic body with male conductors which have crimp means. There is a molded plastic body and at least two male electrical conductors, the conductors each having a first end, a body engaging portion, and a crimp end with crimp means. The plastic of the body is hard, though resilient, and has a front portion, a rear portion and at least two through openings for the conductors. The through openings are spaced apart a distance to appose the spaced openings in the female receptacle and have a span in a range between approximately 125 and 187 thousandths of an inch. The shape of the openings is selected to retain a conductor at the conductor&#39;s engaging portion. The conductors are engaged in the through openings, firmly retained in the openings, each positioned to address the openings in a female outlet receptacle. 
     The conductors may be blades and a round pin. The body has through openings for the conductors. The body may have more than one further opening between the front portion and the rear portion. 
     The through openings may have peripheral bevels on the rear portion. The blades may have strain reliefs, such as stop arms, to engage the rear portion of the body and may include a dimple to engage the front portion of the body. 
     The round pin may have a strain relief such as a stop arm, to engage the rear portion of the body and may have interactive means, such as a burr or D shape on the engaging portion, to engage the through hole against rotation and disengagement of the pin. 
     The through openings may have a span in a range between approximately 090 and 0.400 thousandths of an inch and the front portion and the rear portion of the body may define a thickness of the body in a range between approximately 0.125 and 187 thousandths of an inch. 
     The front portion and the rear portion of the body may also define a thickness in a range between approximately 090 and 400 thousandths of an inch. 
     The conductors each may have wire engaged in the crimp means and the assembly may be over molded with plastic to form a plug. 
     A premold assembly for a molded plastic electric outlet plug may have male conductors to engage in openings in an electrical outlet female receptacle&#39;s three spaced openings for blades and a ground pin. The assembly may have a molded plastic body with two blades and a round pin which have crimp means. The conductors each may have a first end, a body engaging portion, a stop arm and a crimp end with crimp means. The plastic of the body is hard, though resilient, and has a front portion, a rear portion and three through openings for the conductors. The through openings are spaced apart a distance to appose the spaced openings in the female outlet receptacle and have a span in a range between approximately 125 and 187 thousandths of an inch. The shape of the openings is selected to retain a conductor at the conductor&#39;s engaging portion. The conductors are engaged in the through openings, firmly retained in the openings each positioned to address the openings in the female receptacle. The body may have more than one further opening between the front portion and the rear portion. The interactive means on the engaging portion of the round pin to engage the through hole against rotation of the pin may be a burr. 
     Although such novel feature or features believed to be characteristic of the invention are pointed out in the claims, the invention and the manner in which it may be carried, may be further understood by reference to the description following and the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a rear elevation of the plastic support of the present invention. 
     FIG. 2 is a right side elevation of FIG.  1 . 
     FIG. 3 is a rear isometric view of the plastic support of the present invention with two blades and a round pin engaged. 
     FIG. 4 is a front isometric view of FIG.  3 . 
     FIG. 5 is a left side elevation of FIG.  3 . 
     FIG. 6 is a right side elevation of FIG.  5 . 
     FIG. 7 is a front elevation of FIG.  5 . 
     FIG. 8 is a top plan view of a stamping strip of male blades usable in the plastic support of the present invention. 
     FIG. 9 is a right side elevation view of FIG.  7 . 
     FIG. 10 is a top plan view of a stamping strip of round pins on an end strip shown in phantom, usable in the plastic support of the present invention. 
     FIG. 11 is a right side elevation view of FIG.  10 . 
     FIG. 12 is a top plan view of FIG.  11 . 
     FIG. 13 is a top plan view of a plug with the plastic support assembly of the present invention. 
     FIG. 14 is a side elevation of FIG. 13 with the plug in phantom. 
     FIG. 15 is an enlarged cutaway detail at A of FIG.  11 . 
     FIG. 16 is an alternate enlarged cutaway detail of FIG.  15 . 
    
    
     Referring now to the figures in greater detail, where like reference numbers denote like parts in the various figures. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIGS. 1 and 2 the plastic support  10  is shown with a body  11  and a blade openings  12  and a round pin opening  13 . There is a through hole  14  in the body  11 . The blade openings  12  includes a small peripheral bevel  15  and the pin opening  13  has a small circumferential bevel  16 . The plastic support has a front portion  17  and a rear portion  18 . 
     As shown in FIGS. 3-6, the round pin  30  is engaged in the pin opening  13 . Blades  40  are engaged in the openings  12 . 
     As can be seen in FIGS. 13 and 14, a plug  50  is molded over the body  11  of the plastic support  10 , with blades  40  engaged in the openings  12  and a round pin  30  engaged in the opening  13 . The body  11  is slightly set back from the conductor extending end of the plug  50  overmolded with plastic. The wire  63  of the cable  60  is crimped at the crimp arms  34  at the crimp end  33  of the round pin  30 . The wires  61  and  62 , respectively, are crimped to the crimp arms  44  at the crimp end  43  of the blades  40 , all in the body  11  of the plastic support  10 . 
     As can be seen in FIGS. 8 and 9, the blades  40  are made from stamped folded metal. The sides  41 ,  42  are folded over from the end  47 . The blade  40  has a crimp end  43 . There are crimp arms  45  on the crimp end  43 . Extending from the first side  41  is a strain relief  45 . An elongated dimple  46  protrudes from the first side  41 , spaced away from the strain relief  45 . In FIG. 8, a stamping strip  48  with two blades  40  is shown. 
     Blades  40  on the stamping strip  48  are substantially severed, but for a small connecting portion (not shown) between the blades  40 . The connecting portion enables the blades  40  to be held in coils or rolls and delivered in situ for automated procedures. 
     As shown in FIGS. 10,  11  and  12 , the round pin  30  has an end  31 , a shank  32  and a crimp end  33 . There are crimp arms  34  extending from the crimp end  33 . Stop arms  35  extend from the base  37  of the shank  32 . Each round pin  30  has burrs  36  in ridges  39  near the base  37 . 
     FIG. 15 shows an enlarged detail at A in FIG. 11, of a burr  36  extending from the ridges  39 . FIG. 16 shows an alternate embodiment, a D shaped burr  36 ′ extending from the ridge  39 . 
     OPERATION 
     As shown in FIGS. 1 and 2, the body  11  of the plastic support  10  has blade openings  12  and a pin opening  13 . The blade opening  12  has a peripheral bevel  15  which serves as a guide for the insertion of blades  40 . The pin opening  13  has a circumferential bevel  16  which serves as a guide to aid the insertion of a round pin  30 . 
     As can be seen in FIGS. 3-6, the plastic support  10  is shown with the round pin  30  and two blades  40  engaged in the respective pin opening  13  and blade opening  12  in the body  11 . 
     Once the blades  40  and round pin  30  are engaged in the body  11 , the plastic support  10  is ready to have the wires  61 - 63  from the cable  60  crimped at the appropriate crimp end  33 ,  43 , to the appropriate crimp arms  34 ,  44 . 
     The assembly process may be done manually. With blades  40  in a stamping strip  48 , as shown in FIG. 8, the blades  40  may be fed from a coil or roll (not shown) and automatically inserted into the blade openings  12  of the body  11  guided by the bevels  15  as they are severed from the stamping strip  48 . 
     By the same token, round pins  30  on a stamping strip  38 , shown in phantom in FIGS. 10,  11 , may be manually or automatically assembled. The pin  30  is inserted into the opening  13  guided by the bevel  16 . 
     Once assembled by any means, the assembled unit of plastic support  10 , round pin  30  and blades  40 , may then be crimped or automatically assembled by simultaneous crimping into a cord set  70 , as shown in FIGS. 13,  14 . The assembly is then moldable to form the plug  50 . 
     As can be seen in FIG. 5, the blade  40  engages the body  11  with the strain relief  45  extending from the first side  41  and abutting the body  11  on one side. The elongated dimple  46  engages the body  11  on its other side holding the blade  40  firmly against disengagement from the opening  12  in the body  11 . 
     The stop arms  35  act as a strain relief for the round pin  30  engaged in the body  11 . 
     Thus, after the molding process, in actual use, the blades  40  and round pin  30  are not likely to be moved or disengaged under the stress of use, testing or in being removed from the mold. The blades  40  and pin  30  are more firmly held in the body  11  of the plastic support  10  than they would be if only held crimped to the wires  61 - 63  in the molding plastic of the plug  50 . 
     As can also be seen in FIG. 5, the burrs  36  engage the inside of the pin opening  13 , holding the pin  30  against rotation. The holding is particularly important where units of the plastic support  10  with blades  40  and pin  30  engaged are used in an automated crimping operation. The burrs  36 , thus maintain the orientation of the crimp arms  34  on the crimp end  33 , to enable simultaneous crimping of all terminals with a minimum of difficulty. The burrs  36  also keep the round pin  30  from falling out of the opening  13 . 
     Once molded into a plug  50 , the molding plastic forms an immovable bond within the plug  50  between the plastic support  10  and the engaged round pin  30  and blades  40  in the body  11 . The plastic, through hole  14  of the body  11  of the plastic support  10  immovably bonds the assembly of the plastic support  10 , blades  40  and pin  30  with the plug  50 . 
     The round pin  30  preferably has an end cap  29 , as can be seen in FIG. 6 at the base  37 , sealing the inner portion of the shank  32  during molding against plastic inflow. 
     The body  11  of the plastic support  10  is preferably of a hard plastic so that the blades  40  and pin  30  are securely held. The plastic support  10  has a thickness  19  defined by the front portion  17  and the rear portion  18 . The thickness  19  is preferably a bit less than the space between the strain relief  45  and the elongated dimple  46 . The blade  40  and body  11  of the plastic support  10  are mutually sufficiently resilient to to enable the dimple to pass through the opening  12  and then engage the front portion  17  to hold the blade  40  in the body  11 . Bearing surfaces  49  on the elongated dimple facilitate its passage through the opening  12  and retention of the blade  40  at the front portion  17 . 
     The thickness of the body  11  over its entire dimension displaces molding plastic. Such displacement may allow economies in material as hereinbefore set forth. 
     An important function of the thickness of the body  11  is that it can define the gripping span of the blade openings  12  and the pin opening  13 . 
     An objective of the plastic support  10  is to provide a body  11  that can firmly hold the conductors, pin  20  and blades  40 , in position to be simultaneously crimped to wires  61 - 63  and held in the body  11  in proper position to be molded into the plug  50  aligned to engage in the female openings (not shown) of a conventional electrical outlet female receptacle. Therefore openings  12  and  13  are preferably in intimate contact with the pin  30  and blades  40  to hold them. 
     The openings  12  and  13  must have a span sufficient to maintain a pin  30  or blades  40  against unwanted movement or misalignment. It is convenient for this span to be defined by the thickness of the body  11 . 
     The span of the openings  12  and  13  must be sufficient to hold the shank  32  of the pin  30  near the base  37  against wobble once engaged and the hold the end of the first side  41  and second side  41  of the blade  40  against wobble once engaged. The span may vary depending on the nature of the plastic used for the body  11 . Nylon is a good plastic for the body  11  of the support  10 . It is hard and rigid with some resilient and can firmly hold a pin  30  and a blade  40 . 
     Among the variables to be considered in selecting the span of the openings  12  and  13 , which may be determined by the thickness of the body  11 , are the plastic support&#39;s  10  volume, hardness, resilience, the leverage of the pin  30  or blade  40  at the openings  12  and  13  as a fulcrum, the characteristics of the plug&#39;s  50  molding plastic and its cost, the cost the metal of the blade held in span, the jostling in handling of the cord set  70  being crimped and then placed into a mold. 
     It is believed that span of the openings should vary from 0.090 to 0.400 of an inch. A preferred range would be between 0.125 to 0.187 of an inch. A preferred embodiment of the span is 0.140 of an inch. Although not shown, it must be remembered the molded span need not be limited by the basic thickness of the body  11 . The gripping span may extend from the body  11  or be diminished by it shape such as by the bevels  15 ,  16 . 
     The terms and expressions which are employed are used as terms of description; it is recognized, though, that various modifications are possible. 
     It is also understood the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might fall therebetween.