Abstract:
A removable molding tab facilitates loading component parts into a mold by providing a body with holding configurations suitable to releasably secure the component parts in mold ready positions. The component parts are loaded into a mold as a preassembly with the removable tab. The tab is removed after the component parts are placed into the mold.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefits of U.S. Provisional Application Ser. No. 61/168,723 filed Apr. 13, 2009. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to injection molding processes and apparatuses used therefore. More specifically, the present invention pertains to devices for preassembling or positioning components which are to be at least partly encapsulated by plastic in an injection molding process. 
       BACKGROUND OF THE INVENTION 
       [0003]    Injection molding can be used to form parts that have complex shapes and features. It is known to use injection molding to encapsulate other parts or components, such as stamped metal conductors in the manufacture of electrical parts. A simple example is the common formation of a plastic plug head on the end of an electrical cord. Electrically conductive metal blades for the plug are electrically connected to wires. The blades are then positioned in a mold where plastic is injected to encapsulate an inner end portion of the blades as well as the blade-to-wire connection. The portions of the blades not to be encapsulated in plastic, the portions that are to remain exposed for electrical connection to another cord or to an electrical outlet, are inserted into narrow slots in the mold steel, the slots leaving insufficient space around the blades for the injected plastic to flow therein. More complex processes are used for more complex products, but the general process remains the same, with parts of components encapsulated in the injection molded plastic and other parts not encapsulated. 
         [0004]    When molding plastic parts, it is desirable to maintain a specific cycle time, i.e. the time required to initiate the process for the part, mold the part and remove the part from the mold to start the next cycle. Desirably, the cycle time is sufficiently short to keep the plastic resin from degrading due to exposure to excessive heat in the molding machine injection unit, and to make the part in the allotted time. 
         [0005]    It is known in the plastic injection molding industry that encapsulating a metal stamping that possesses multiple circuits creates a challenge if the multiple circuits must be handled and loaded into the mold by a human molding operator. It is desirable to load multiple circuits in a timely manner to maintain a specific cycle time. The more circuit components that must be loaded into a mold, the more time it takes to prepare the component parts before the actual step of injecting the plastic can be initiated. The same is true for any molding process in which multiple individual component parts have to be positioned in the mold before plastic injection can be initiated. Accordingly, it is desirable to shorten the time it takes for a mold operator to load metal stampings with multiple circuits, or other individual component parts, so that mold use efficiency is optimized. 
         [0006]    It is known to attach multiple circuits together as a one-piece stamping assembly that a molding operator can load into a mold as a single piece. A known way to attach multiple circuits is to connect them via a “tie-bar”, which is a portion of the metal stamping which is left between two or more circuits during the stamping process. Several tie-bars can be used to hold multiple circuits together, effectively creating a one-piece stamping for handling purposes. After the plastic part is molded, the tie-bar or tie-bars must be removed, often using a trim die that cuts or stamps the tie-bar from its position between the circuits, thereby effectively separating the circuits both physically and electrically. The use of a trim die in this way creates an open hole through the part when the die is pushed through the part to remove the tie-bar connection. A trimming operation adds additional cost to the part due to the additional handling after molding, and also requires the part to be designed in such a way as to have access to any tie-bars from both sides of the molded part for the trimming operation. In some part designs, it is difficult, if not impossible, to have the space required for tie-bars; or it may not be acceptable or desirable to have an open hole through the finished part. Some plastic parts must be sealed from one side of the part to the other side of the part, and having an open hole through the part must be avoided. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a removable holder for a temporary assembly that allows handling of multiple circuits, or multiple stamped or other individual component parts as one piece to maintain the desired mold operation cycle time; while also eliminating the need for the molded part to go through a post-molding trimming operation to remove tie-bars or other physical connectors between the component parts. 
         [0008]    In one aspect of one form of a molded pull-off tab to be preassembled to multiple individual component parts to be loaded in an injection mold, the tab is provided with a body having a plurality of component receiving and holding formations, each of the formations being configured for holding one of the component parts. The formations are positioned in the body to hold the component parts in mold ready positions for direct loading into a mold. The formations are configured to readily release the component parts positioned in the mold and to be removed therefrom prior to molding. 
         [0009]    In another aspect of a form of a molded pull-off tab, a body of the tab has a plurality of component receiving and holding formations each configured for holding an end of an electrical conductor. The formations are positioned in the body to hold the electrical conductors in mold ready positions for direct loading into a mold, and the formations are configured to be removed from the electrical conductors when the conductors are positioned in a mold part. 
         [0010]    In still another aspect, a method for loading a mold with components to be at least partly encased in plastic has steps of obtaining the components; preassembling the components in a removable tab in mold ready positions to establish a temporary assembly of the tab and the components; placing the temporary assembly in a mold part; removing the removable tab from the temporary assembly in the mold part; and closing the mold with the components therein and with the tab removed. 
         [0011]    Advantages of forms of the invention are that multiple component parts can be prearranged and secured as a single, temporary assembly suitable for placement in a mold, and thereafter separated before injection molding occurs, so that at completion of the molding cycle the individuality of the component parts is present. This can be achieved whether the molding process is for a single part having multiple discrete components encapsulated in a single molded body, or for creating several discrete molded parts in a single mold during the process 
         [0012]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a step in an exemplary process for installing a pull-off tab on electrical conductors; 
           [0014]      FIG. 2  is a perspective view of a temporary assembly using the pull-off tab and electrical conductors shown in  FIG. 1 ; 
           [0015]      FIG. 3  a cross-sectional view of the temporary assembly installed in a mold part for making a connector using the conductors; 
           [0016]      FIG. 4  a cross-sectional view of the conductors positioned in the mold and the pull-off tab removed; 
           [0017]      FIG. 5  a cross-sectional view of the conductors and mold in closed and final positions for molding the connector; 
           [0018]      FIG. 5A  cross-sectional view of the finished molded connector; 
           [0019]      FIG. 6  is a perspective view of a step in an exemplary process for installing a pull-off tab of another embodiment on electrical conductors similar to those shown previously; 
           [0020]      FIG. 7  is a perspective view of a temporary assembly using the pull-off tab and electrical conductors shown in  FIG. 6 ; 
           [0021]      FIG. 8  a cross-sectional view of the temporary assembly installed in a mold for making a connector using the conductors, which can be the same mold shown previously; and 
           [0022]      FIG. 9  a cross-sectional view of the conductors positioned in the mold and the pull-off tab of  FIG. 8  removed. 
       
    
    
       [0023]    Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use herein of “including”, “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof, as well as additional items and equivalents thereof. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0024]    Referring now more specifically to the drawings and to  FIG. 1  in particular, a molded pull-off tab  10  is shown. Pull-off tab  10  can be a molded or otherwise formed plastic body, a formed body of other material, or the like; and includes component receiving and holding formations  12 ,  14 ,  16  therein. In the exemplary embodiment shown in  FIGS. 1-4 , component receiving and holding formations  12 ,  14 ,  16  are pockets having openings along one side of pull-off tab  10 , and pull-off tab  10  is essentially a rectangular block or body of monolithic material. However, it should be understood that pull-off tab  10  can be of other shapes as well. 
         [0025]    Electrical conductors  18 ,  20 ,  22  are received in component receiving and holding formations  12 ,  14 ,  16 , respectively. Each electrical conductor  18 ,  20 ,  22  is securely held in the respective receiving and holding formation  12 ,  14 ,  16  for transportation, handling and loading into a suitable mold wherein plastic will be injected for encapsulating an exposed portion of the conductors. Each individual component, such as electrical conductors  18 ,  20 ,  22  of the exemplary embodiment, is held by the pull-off tab in a mold ready position with respect to the other components so that the components can be loaded into a mold as a single temporary assembly, with little or no individual manipulation of the individual components. Portions of the conductors not held in the molded pull-off tab  10  can be positioned in parts of the mold either to be shielded from the injected molded plastic or to be encapsulated thereby. Molded pull-off tab  10  of the exemplary embodiment receives and holds portions of conductors  18 ,  20 ,  22  that are subsequently received in the mold steel and are not exposed in the open mold part, to be encapsulated in injected plastic. However, it should be understood that pull-off tabs for other uses might receive and hold portions of items to be exposed in the mold cavity and to be encased in plastic. 
         [0026]    Molded pull-off tab  10  can be assembled onto conductors  18 ,  20 ,  22  as a step during the stamping or other process used to form the conductors. Automatic, mechanical assembly or hand assembly of molded pull-off tab  10  to multiple component parts such as conductors  18 ,  20 ,  22  can be accomplished quickly and efficiently. Assembly of molded pull-off tab  10  onto conductors  18 ,  20 ,  22  may be performed before the conductors are fully separated one from another and with the conductors in the final position and orientation required for the subsequent molding operation.  FIG. 1  shows a step in a stamping process in which conductors  18 ,  20 ,  22  are formed but not yet separated from a supply strip  24  of the material from which conductors  18 ,  20  and  22  are formed. Conductors  18 ,  20 ,  22  include terminal ends  28 ,  30 ,  32 , respectively, that are received in holding formations  12 ,  14 ,  16  respectively. After pull-off tab  10  is connected to the conductors, the conductors can be separated one from another and from the supply strip  24  to form conductor ends  38 ,  40 ,  42  opposite from terminal ends  28 ,  30 ,  32 , as shown in  FIG. 2 . Thereafter, the multiple component parts such as conductors  18 ,  20 ,  22  can be handled as a single assembly, securely held by molded pull-off tab  10 ; however, each conductor  18 ,  20 ,  22  is a separate and discrete component. 
         [0027]    In another assembly process, individual electrical conductors can be inserted into molded pull-off tab  10  after complete formation and separation from the supply strip. Manual or mechanical assembly can be used. 
         [0028]    In preferred embodiments of pull-off tabs, the spacing between individual component receiving and holding formations is such as to secure the electrical conductors in mold ready positions for efficient loading into a mold. 
         [0029]    The temporary assembly of molded pull-off tab  10  on conductors  18 ,  20 ,  22  can be handled for shipping and loading into a mold as a single unit. Once the component parts such as conductors  18 ,  20 ,  22  have been at least partially positioned in the mold, pull-off tab  10  is removed by pulling, twisting or the like, and molding proceeds in a standard, known manner. The finished parts are formed with conductors  18 ,  20 ,  22  fully separated as required. Handling of the multiple conductors as a single assembly via pull-off tab  10  reduces the time and manipulation required from the molding operator. The assembly of multiple components into an individual, removable holder, such as pull-off tab  10 , can also facilitate mechanical handling or loading into a mold in an efficient, time-saving manner. 
         [0030]    It should be understood that the molded pull-off tabs are specifically designed, shaped and configured for holding the particular component parts to be secured therein. Each pull-off tab can hold as many individual components as ergonomically advantageous for either manual or mechanical handling, and as suitable for loading into a mold. The shape and configuration of pull-off tab  10  and the connection of the component parts thereto are such as to position the component parts in an advantageous relationships one with another for loading into the mold in which the part or parts will be completed. The pull-off tab can be positioned at an end of the component parts, or can be positioned at some intermediate position along the component parts, as desirable to facilitate loading the ganged component parts into a mold. 
         [0031]      FIG. 1  illustrates closed pockets for holding conductors  18 ,  20  and  22 . However, open slots also can be used.  FIG. 6  illustrates a pull-off tab  50  having component receiving and holding formations  52 ,  54 ,  56  therein in the nature of open slots. Electrical conductors  58 ,  60 ,  62  can be pushed into slots  52 ,  54 ,  56 , either mechanically or manually, so that the temporary assembly of pull-off tab  50  and conductors  58 ,  60 ,  62  held thereby can be handled as one assembly. As with the previous embodiment, electrical conductors  58 ,  60 ,  62  can be formed from a supply strip  64 , and terminal ends  68 ,  70 ,  72  of electrical conductors  58 ,  60 ,  62  can be inserted into slots  52 ,  54 ,  56  either through open ends of the slots or from the top openings to the slots before the individual conductors are separated from the supply strip. Alternatively, individual conductors can be attached to the pull-off tab after separation from the supply strip by manual or mechanical processes. 
         [0032]    It should be understood that still other shapes, sizes and configurations for a molded pull-off tab can be used for many different types of component parts, including component parts other than the electrical conductors illustrated. The particular shapes, sizes, configurations and numbers of parts and formations are merely exemplary in nature and should not in any way be considered limiting on the principles and features. While the exemplary embodiments show pull off tabs for holding individual components used to make a single part, a pull off tab also can be used to hold individual components when multiple parts are formed in a single mold. While one temporary assembly of a pull-off tab and electrical conductors is shown, it should be understood that multiple temporary assemblies including several pull-off tabs and component parts held therein can be used in a single mold, either to position multiple components in a complex structure or to provide components for molding multiple individual parts in a single molding process. Accordingly, the component parts held by one pull-off tab can be the same as or different from the component parts held by other pull-off tabs, and a single pull-off tab can hold different types of component parts. 
         [0033]    As shown in  FIGS. 3-5 , the temporary assembly of molded pull-off tab  10  and the electrical conductors  18 ,  20 ,  22  can be loaded into a first mold part  90 , with molded pull-off tab  10  then removed before the mold is closed by engaging a second mold part  92 . The temporary assembly of molded pull-off tab  10  and electrical conductors  18 ,  20 ,  22  is manipulated so as to position conductor ends  38 ,  40 ,  42  into slots  94  of first mold part  90 , which may have a separate slot  94  for each conductor and  38 ,  40 ,  42 . Molded pull-off tab  10  is removed by pulling laterally. Thereafter, second mold part  92  is positioned with slots  96  thereof receiving terminal ends  28 ,  30 ,  32  of the conductors. Standard molding procedures can be followed, including any necessary overmolding, so as to form a completed electrical connector  110  having molded portions  112 ,  114  surrounding the electrical conductors  18 ,  20 ,  22 . 
         [0034]    As shown in  FIGS. 8 &amp; 9 , a temporary assembly of molded pull-off tab  50  and the electrical conductors  58 ,  60 ,  62  can be used in the same mold having mold parts  90 ,  92 . First mold part  90  is provided with a slot  94  for each conductor end. The conductor ends  78 ,  80 ,  82  are inserted into the slots, and tab  50  is then removed by pulling or twisting relative to the conductors so that terminal ends  68 ,  70 ,  72  are released from component receiving and holding formations slots  52 ,  54 ,  56 . The mold is closed and a similar electrical connector can be formed. 
         [0035]    Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art. 
         [0036]    Various features of the invention are set forth in the following claims.