Abstract:
An invention is provided which employs a self-adjusting core section having an outer diameter which essentially matches that, or is larger than that, of the inner diameter of a wire coil, where the self-adjusting core has a vertical slit along the its length to allow the diameter of the core to be adjustable. Bridging the vertical slit are straps secured to the core to determine the core&#39;s maximum diameter, and allow the core diameter to be reduced through flexing.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to self adjusting payoff core, more specifically to a self-adjusting payoff core used with wire coils employed in welding operations, and other similar applications. 
     BACKGROUND OF THE INVENTION 
     In some welding operations, such as MIG welding, a wire coil is employed to provide a continuous feed of welding wire (electrode) to the welding gun. In these applications, the welding wire is often stored in a large coil configuration, in which the coil of wire is placed in a box or a container having a core section around which the wire is coiled. The core section is employed to maintain coil stability as the wire is pulled out of the box during the welding operation. 
     However, there are problems associated with this configuration. First, as the wire is pulled from the container the loop diameter of the wire becomes smaller (due to the pulling tension on the wire). Because of this, the wire falls between a gap between the core section and the wire coil, and can fall as far as the bottom of the container. This falling of the wire greatly increases the friction between the wire and the core section, thus increasing the friction force and required feed force to draw the wire out of the container. The gap is created by the use of a core section having a diameter smaller than that of the inner diameter of the wire coil, which is needed to allow the core section to be easily placed in the center of the wire coil. Secondly, the core section can move and/or be tilted during the wire payout which causes similar problems which increase the required feed force. For example, the wire can fall under the core section or be bound by the tilted core section. 
     Therefore, there is a need for a payoff core configuration which is capable of addressing the above problems. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to solve the above problems by providing a low cost and reliable system to allow for low friction and consistent wire payout during a wire feed operation, in wire coil containers of various sizes having wire coils of varying sizes and diameters. 
     To accomplish this, an embodiment of the present invention employs a self-adjusting core section having an outer diameter which essentially matches that, or is larger than, of the inner diameter of the wire coil, where the self-adjusting core has a vertical slit along its length to allow the diameter of the core to be adjustable. Bridging the vertical slit are straps secured to the core to determine the core&#39;s maximum diameter. 
     Various embodiments of the present invention will be discussed in more detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages, nature and various additional features of the invention will appear more fully upon consideration of the illustrative embodiments of the invention, which are schematically set forth in the figures, in which: 
         FIG. 1  is a diagrammatical representation of a self-adjusting payoff core according to an embodiment of the invention; 
         FIG. 2  is a diagrammatical representation of the self-adjusting payoff core of  FIG. 1  in a squeezed configuration; 
         FIG. 3  is a diagrammatical representation of a self adjusting payoff core according to an alternative embodiment of the present invention; 
         FIG. 4  is a diagrammatical representation of an embodiment of the present invention placed in a wire coil box along with a wire core; and 
         FIG. 5  is a diagrammatical representation of another embodiment of a self-adjusting payoff core in accordance with the present invention. 
         FIG. 6  is a diagrammatical representation of a further exemplary embodiment of a self-adjusting payoff core in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The present invention relates to a self-adjusting payoff core employed in a wire coil container, such as those employed in welding operations, to allow for low and consistent feed force during wire payout. 
       FIGS. 1 and 2  depict a self-adjusting payout core  100  according to an embodiment of the present invention. The core  100  contains a wall section  10  which is essentially cylindrical in shape having a slit section  12  running vertically along a length of the wall section  10 . This slit section  12  creates a gap between edges  14  of the wall section  10  such that a diameter and thus cross-section of the core  100  is adjustable, as the gap  14  is reduced or enlarged. 
     Bridging the gap  14  are a plurality of straps  16  secured to the wall section  10 . The straps  16  are made from a flexible material, allowing the wall section  10  to be deflected, thus enabling the gap  14  to be reduced. Further, the straps  16  are strong enough, and secured in such a fashion, so as to maintain a maximum diameter of the core  100 .  FIG. 2  depicts the core  100  where the gap  14  is reduced, thus the core  100  has a smaller diameter/cross-section then when the straps  16  are extended. 
     The wall section  10  can be made of any commonly known material having a level of flexibility which allows the wall section  10  to be deflected the needed amount, and sufficient elasticity to rebound after pressure is released. This will ensure that the core  100  can be continually reused, and will continually apply pressure against the inner diameter of the wire coil. For example, the wall section  10  can be made from cardboard, plastic, thin metal sheet, and other similar or comparable materials. 
     The straps  16  can be made of any known flexible material, such as rubber, cloth, plastic, metal, etc. which allows the wall section  10  to be deflected so that the gap  14  may be reduced by the desired amount. The straps  16  may be secured to the wall section  10  by any known means or methodology, such as an adhesive or fasteners, which ensures that the straps  16  remain secured to the wall  10 . In an alternative embodiment the straps  16  are formed integrally with the wall section  10 , and both the wall section  10  and straps  16  are made from a material having a sufficient strength and flexibility, as needed. 
     Further, although  FIGS. 1 and 2  show two straps  16 , the present invention is not limited to this configuration, as the number of straps  16  can be as few as one, and more than two. Moreover, in a further embodiment, the straps/strap  16  have a sufficient width so as to cover the entire length of the slit  12 , or at least 50% of the slit length, as shown in  FIG. 6 . Such configurations would prevent the wire from snagging or otherwise being caught on the straps  16  during payout. 
     A maximum outer diameter/cross-section of the core  100  is to be selected based on an inner diameter of the wire coil into which the core is to be inserted. In an embodiment of the present invention, the maximum outer diameter of the core  100  is to be approximately the same or larger than the inner diameter of the wire coil, into which it is to be inserted. For example, if the inner diameter of the wire coil is 400 mm, the maximum outer diameter of the core  100  can be in the range of 400 to 405 mm. It is also recognized, however, that the diameter is not required to be exactly the same diameter as the inner diameter of the coil, but can be slightly less, so long as the diameter is sufficiently large enough that the wire is prevented from falling between the core  100  and the wire coil. 
     During installation, the core  100  is squeezed to allow for easy insertion into the wire coil, and when the core  100  is in its place, the core  100  is allowed to expand to the inner diameter of the coil, thus eliminating any potential gap between the core  100  and the wire coil. Thus, upon installation the diameter of the core  100  is essentially or approximately that of the inner diameter of the wire coil. It is recognized that at some points of contact between the core  100  and the wire coil, the diameters essentially match, but this may not be consistent around the entire circumference of the core  100  due to at least manufacturing accuracies, the shape of the core, and the presence of the gap  14 . However, as long as the core  100  diameter is sufficiently large at some points so as to prevent the problems discussed above, the benefits of the present invention will be attained. 
     Further, in addition to addressing the problems discussed above, the present invention permits the use of a single core  100  along with a plurality of different size wire coils having different inner diameters, thus allowing for easy interchangeability and cost savings. 
       FIG. 3  depicts a further embodiment of the present invention, where the core  300  is similar in construction to the core  100  in  FIGS. 1 and 2 , but the core  300  is conically shaped. In additional embodiments the self-adjusting core may have a cross-sectional shape which is not circular, but can be of any cross-section which sufficiently supports the wire coil and adequately supports the wire during the wire payout operation. For example, the core can have an octoganol or pentagonal cross-section. It is further understood that it is not necessary for the core  100 / 300  of the present invention to have an exact geometric cross-section (such as circular, octagonal, etc.). For example, the operation of the present invention would not be compromised if the cross-section was not exactly circular, but was essentially or basically circular. Namely, it is recognized that for various reasons, such as the existence of the gap, the cross-section of the core  100 / 300  may be approximately circular or octagonal, etc. 
     In a further exemplary embodiment of the present invention, shown in  FIG. 5 , the core  500  is constructed as a solid body, but is made from a flexible or compressible material. For example, the core  500  may be made from a foam or sponge like substance which is relatively easily compressible. The operation of this embodiment is similar to that described above. Specifically, the compressible core  500  is squeezed or compressed as it is placed within a wire container, and when the squeezing pressure is releases the core  500  returns to its original shape. The compressibility of the core  500  is to be such so that it is relatively easily compressed to allow for its installation and removal, but also have sufficient rigidity so as to allow for the proper payout of wire, as described herein. In a further aspect of this embodiment, the core  500  is not solid, but is shaped similar to that shown in the Figures. Further, in another embodiment the core  500  is solid except for a wedge portion  501 . The wedge portion  501  allows the core  500  to compress easier. 
       FIG. 4  depicts an embodiment of the present invention in a wire coil container  400 . The container  400  can be of any commonly known shape or configuration used to hold a wire coil, such as square, rectangular, circular, octagonal, etc., and can be made of any commonly known or used materials. Within the container  400  is a wire coil  40  of welding wire (or any other wire or material) which is coiled in a cylindrical shape. The wire coil  40  has an inner diameter/space  44  in which a self-adjusting payoff core  42  is placed. As indicated above, the payoff core  42  has a maximum diameter (when the straps are fully extended) which is approximately the same as or larger than an inner diameter of the wire coil  40 . Thus, when the core  42  is placed within the center of the coil  40  (while being squeezed) the core  42  essentially eliminates any gap(s) between the core  42  and the coil  40 , ensuring that the benefits of the present invention are obtained. 
     To remove the core  42 , the core  42  is squeezed again (reducing the size of the gap) allowing easy removal of the core from the coil  40 . 
     Of course, although the present invention has been discussed with respect to welding wire coils, it is contemplated that the present invention may be used in any applications where a material is coiled and is to be drawn or paid out in a smooth and efficient manner, such that the payout force needed is minimized and similar problems such as those discussed herein are desired to be avoided. 
     The present invention has been described with certain embodiments and applications. These can be combined and interchanged without departing from the scope of the invention as defined in the appended claims. The invention as defined in these appended claims are incorporated by reference herein as if part of the description of the novel features of the present invention.