Patent Publication Number: US-2002002082-A1

Title: Plastic pin

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to a plastic pin, i.e. one of polymeric material, for games, and has a porous and/or cellular core that is surrounded by a tough or resilient shell. The pin has a base that forms a support surface and that is made of a different material than is the shell. The base has a central bore and a plug or socket that proceeds from the rim of the bore and extends into the core of the pin.  
       [0002] Within the context of the present application, plastic pins for bowling lanes include so-called bowling pins and nine pins.  
       [0003] It is desirable to use different materials for the base of the pin on the one hand, and for the shell thereof on the other hand; for example, polyamides and polypropylenes are suitable for optimally satisfying the specific requirements of different portions of the pin. However, during manufacture of the pins different materials do not always provide the desired intimate bonding.  
       [0004] It is an object of the present invention to provide a good and improved connection between the base of the pin on the one hand and that portion of the pin shell disposed thereabove on the other hand. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
     [0005] This object, and other objects and advantages of the present invention, will appear more clearly from the following specification in conjunction with the accompanying schematic drawing, in which:  
     [0006]FIG. 1 is a plan view of one exemplary embodiment of an inventive pin;  
     [0007]FIG. 2 is a partially cross-sectioned view of the lower portion of the pin of FIG. 1; and  
     [0008]FIG. 3 is a cross-sectional view of a modification of the pin of FIG. 2, whereby the right and left portions of FIG. 3 show different embodiments.  
     SUMMARY OF THE INVENTION  
     [0009] The pin of the present invention is characterized primarily in that the plug that extends into the interior of the pin is positively connected with the core of the pin by one or more projections. For this purpose, the pin is expediently provided with circumferential ribs, which in turn preferably have a saw tooth shaped cross-sectional configuration.  
     [0010] The plug of the base of the pin, and hence the base itself, are thus anchored to the core, whereby this anchoring can be the sole securing means of the base, or an additional anchoring means can also be provided.  
     [0011] The aforementioned anchoring can be very easily realized pursuant to the present invention. In particular, if the plug that extends into the interior of the pin is provided with the aforementioned projections, and if the material that forms the cellular and/or porous plastic core is introduced into the hollow interior of the pin from below through the plug during manufacture of the pin, the material of the core advances downwardly during introduction thereof to the inner side of the base, whereby such material surrounds the plug on all sides and thereby completes the positive connection. In order in this connection not to disrupt the flow of material, it is advantageous to provide the base with one or more fine venting bores.  
     [0012] Further specific features of the present invention will be described in detail subsequently. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0013] Referring now to the drawing in detail, the pin of FIG. 1 is provided in the customary manner in the base region with a base  1 , thereabove a barrel or bulging portion  2 , which merges into a reduced-diameter neck  3 , and finally a head  4  that has a smaller outer diameter than does the barrel  2 . The components  2 ,  3  and  4  form the shell  5  of the pin. The pin is additionally provided with a core  6  that is preferably adhered or secured to the outside. The core  6  comprises a cellular and/or porous polymeric material and, after completion of the outer casing (the base  1  and the shell  5 ), is formed by introducing an expanding material into the interior of this casing through the central bore  7  in the base  1 .  
     [0014] Whereas the shell  5  is comprised of a polymeric material based on polypropylenes, the base  1  is made of a generally harder polymeric material based on polyamide. Although these materials are suitable, they do not always form an adequately strong bond with one another.  
     [0015] From the rim of the bore  7  in the base  1 , a socket or plug  8  extends perpendicularly upwardly, i.e. into the interior of the pin, for example having a length of about 40-80 mm. The important feature is that the outer surface of the plug  8 , which is monolithically formed with the base  1 , is provided with a plurality of annular projections  9  that are distributed over the height of the plug  8 . The annular projections  9  preferably have a saw toothed cross-sectional configuration, and in particular such that the larger diameter portion of the projections  9  face the base  1 , thus creating corresponding undercuts.  
     [0016] When the material that forms the core  6  is introduced it passes not only into the barrel  2 , the neck  3  and the head  4 , but also in the direction of the arrows  10  into the region of the base  1 , whereby the trapped air can escape via small bores  11  in the base  1 . The plug  8  is thereby surrounded. The strengthening and reinforcing material of the core forms a positive connection between the core  6  and the plug  8  and hence the base  1 . This means that the base  1  is securely connected to the shell  5 .  
     [0017] In order to preclude a lateral shifting, the base  1  can be laterally provided with a rim or flange  12  (shown by dashed lines) that centers the components  1  and  5  relative to one another.  
     [0018] If desired, an adhesive can be effective in the region of the separating faces between the shell  5  and the base  1 . However, the connection of these components is often adequately ensured by the aforementioned positive connection.  
     [0019] In the embodiment illustrated in FIG. 3, where the core  6  is not shown, the base  1  is provided with an upwardly widening plug  8 , in other words, a plug that has an essentially conical exterior surface (the diameter D is greater than the diameter d). This plug  8  also results in a positive connection, i.e. forms a back taper or undercut for the material of the core.  
     [0020] In addition, a hook connection can also be provided between the shell  5  and an upwardly extending rim  13  of the base  1 . For this purpose, the shell  5  can engage in an inwardly disposed circumferential groove  14  of the rim  13  (as shown in the left half of FIG. 3), or the shell  5  can engage in an outwardly disposed circumferential groove  15  of the rim  13  (as shown in the right half of FIG. 3).  
     [0021] It should be noted that in place of the annular, circumferential projections  9 , it would also be possible to use knobs or studs, in other words, projections that extend over only a portion of the periphery of the shell. However, the expedient feature in each case is that adequately large undercuts be provided. A saw tooth configuration is therefore very suitable. In addition, in place of the hook connection it would also be possible to use a differently configured tongue and groove connection.  
     [0022] The specification incorporates by reference the disclosure of German priority document 100 18 917.2 of Apr. 17 2000.  
     [0023] The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawing, but also encompasses any modifications within the scope of the appended claims.