Patent Publication Number: US-7909284-B2

Title: Wire spool alignment method in wire feed welding systems

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Non-provisional Patent Application of U.S. Provisional Patent Application No. 61/038,139, entitled “Wire Spool Alignment Method in Wire Feed Welding Systems”, filed Mar. 20, 2008, which is herein incorporated by reference. 
     BACKGROUND 
     The invention relates generally to welding systems and welding wire feed systems, and more particularly, to systems and methods for mounting welding wire spools of different sizes on a mounting spindle. 
     Many types of welding systems utilize continuously fed consumable wire from a welding gun during welding operation. This wire is provided by manufacturers on wire spools with varying widths and diameters. Common welding applications require spools with widths ranging from 1.75 to 4.25 inches. These spools are placed on a mounting spindle, which is designed to accommodate the largest spool width, for use during welding. Traditionally, a single retaining mechanism is placed on the end of the mounting spindle to prohibit the wire spool from dislodging and to ensure a tight fit. 
     While this system works well for the largest wire spools, alignment and excessive wear problems arise when mounting smaller wire spools. For instance, a spool with a 1.75 inch width will be secured in a position that results in wire being spooled from the wire spool to the wire drive mechanism of the welder at a misaligned angle. This can lead to excessive wear on the inlet guide of the wire drive mechanism and disruption of the weld due to inconsistent wire feeding. Therefore, there exists a need for improved mounting techniques that can offer better welding wire spool alignment for a range of wire spool sizes. Such techniques could be used in both large scale commercial and small scale private welding operations. 
     BRIEF DESCRIPTION 
     The present invention provides a novel system for mounting welding wire spools of different sizes on a mounting spindle of a wire feed system designed to respond to such needs. The invention may reduce or eliminate wire feedability difficulties and welding arc outages arising from misalignment of the wire spool and inconsistent wire feeds. In particular, the invention provides a wire spool mounting system including a spool mounting hub with a movable back plate. The movable back plate has a locking slot arrangement that allows for accommodation of multiple spool widths. The invention provides a system for mounting small wire spools on a shaft of a wire feed system comprised, in certain presently contemplated embodiments, of washers, a spring, and a knurled nut. A braking system including washers, a spring, and a knurled nut may be provided for the prevention of wire spool free wheeling during non-welding periods. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  illustrates a wire feed system with a spool mounting hub in accordance with aspects of the present invention; 
         FIG. 2  is a top plan view of an exemplary spool mounting hub on a keyed shaft with a medium sized spool; 
         FIG. 3  is a top plan view of an exemplary spool mounting hub on a keyed shaft with a large spool; 
         FIG. 4  is an exploded view of the keyed shaft and the exemplary spool mounting hub assembly; 
         FIG. 5  illustrates an exemplary spool mounting hub showing the locking slot arrangement; 
         FIG. 6  is a perspective view of an exemplary spool mounting hub with a moveable back plate in the first slot and a threaded nut plate; 
         FIG. 7  is a perspective view of an exemplary spool mounting hub with a moveable back plate in the second slot and a threaded nut plate; 
         FIG. 8  is a top plan view of an exemplary wire feed braking system in accordance with aspects of the present invention; 
         FIG. 9  is an exploded view of the keyed shaft and the exemplary mounting system for small spools in accordance with aspects of the present invention; 
         FIG. 10  is a top plan view of the exemplary mounting system for small spools of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a wire feed system  10  that supplies a welding operation. The welding operation will typically be a metal inert gas (MIG) operation that utilizes a continuous feed of welding wire as an electrode and consumes the wire during the operation. As will be appreciated by those skilled in the art, however, similar operations may be performed in which weldments are formed without shielding gases, such as by the use of flux-cored wire. The system described herein is envisaged for use with all such operations where spools of wire of different sizes, widths, and diameters are fed to a location where welding is carried out. 
     In the system illustrated, a back wall  12  is permanently affixed to a keyed shaft  14 , which extends outward and contains threads at its outer end. A spool mounting hub  16  fits onto the keyed shaft  14  and properly positions a wire spool  18  that can rotate on the shaft and/or hub to feed wire for welding. In certain embodiments, the spool  18  may have one of several different standard sizes, and the spool mounting hub  16  is adjustable to ensure proper alignment. The wire spool  18  rotates in the indicated direction  20  to feed wire  22  into the inlet guide  24 , which contains an aperture  26  through which the wire  22  enters. The wire  22  is fed through the feed head assembly  28  into the wire drive assembly  30 . Upon exiting, the wire  22  is fed through an opening  32  for use in the welding operation. Due to the direction of rotation of the spool, left-hand threading on the spool mounting hub  16  ensures that the wire spool  18  does not become dislodged (i.e., loosened by unthreading) during this wire feed operation. If the direction of turning of the spool were reversed, this feature of the arrangement may also be changed (e.g., for right-hand threading). 
       FIG. 2  is a top plan view of the exemplary spool mounting hub  16  holding the medium wire spool  18  on the keyed shaft  14  of  FIG. 1 . A wear plate  34  is positioned on the keyed shaft  14  flat against the back wall  12 . The spool mounting hub  16  is then positioned on the keyed shaft  14 . The mounting hub  16  holds a movable back plate  36 , a wire spool  18 , and a threaded nut plate  38 . The movable back plate  36  adjusts inwardly and outwardly to accommodate various spool widths. In certain embodiments, the back plate  36  may have two or more possible positions. In a presently contemplated embodiment, the threaded nut plate  38  is secured on the hub  16  with left-hand threads. The spool hub assembly positions the wire spool  18  such that a centering distance  40  is established, causing the wire  22  to be properly aligned as it feeds into the inlet guide  24 . 
       FIG. 3  is a top plan view of the exemplary spool mounting hub  16  holding a large wire spool  42  on the keyed shaft  14 . A wear plate  34  is positioned on the keyed shaft  14  flat against the back wall  12 . The spool mounting hub  16  is then positioned on the keyed shaft  14 . The mounting hub  16  holds a movable back plate  36 , a large wire spool  42 , and a threaded nut plate  38 . The movable back plate  36  is adjusted outward to accommodate the large spool width. The threaded nut plate  38  is secured on the hub  16  with left threads. The spool hub assembly positions the large wire spool  42  such that a centering distance  44  is established, causing the wire  22  to be properly aligned as it feeds into the inlet guide  24 . The centering distance  44  for the large wire spool  42  is approximately equal to the centering distance  40  for the medium wire spool. The positions of the back plate  34  and the threaded nut plate  38  adjust to keep this distance  44  approximately constant for various wire spool widths, ensuring proper wire alignment for all spool sizes. 
       FIG. 4  is an exploded view of the assembly of the spool mounting hub  16  that secures and aligns wire spools for welding. The keyed shaft  14  extends out from the wear plate  34 , which provides a base for the parts of the assembly. The keyed shaft  14  has a keyway  46 , which extends approximately 75% of the way down the shaft  14  toward the wear plate  34 . The movable back plate  36  connects to the locking slot arrangement  48  on the spool mounting hub  16 . The threaded nut plate  38  mounts on the left threads  50  on the opposite end of the spool mounting hub  16  and tightens in the opposite direction of the wire spool feed. A keyed washer  52  is then mounted on the keyed shaft  14 . A spring  54  is provided to secure the assembly in the desired position and prevent the wire spool from unraveling when a welding operation is not occurring (e.g., by applying a preload force to the assembly). An outer keyed washer  52  is then added followed by a knurled nut  56 . The user may tighten the nut  56  by gripping threads  58  to manually adjust the force on the hub assembly. 
       FIG. 5  is a perspective view of the spool mounting hub  16  illustrating the left threads  50  on the outer end and the locking slot arrangement  48  on the other end. The movable back plate  36  slides onto the axial common slot  60  during use. For smaller spools, the back plate  36  then rotates clockwise through the first circumferential extension  62  and slides axially back into the first locking recess  64 . For larger spools, after sliding onto the axial common slot  60 , the back plate  36  rotates clockwise through the second circumferential extension  66  and slides axially back into the second locking recess  68 . Certain embodiments may have more or less recesses than the spool mounting hub  16  shown. 
       FIG. 6  illustrates the spool mounting hub  16  with the movable back plate  36  secured in the first locking recess  64  of the locking slot arrangement  48 . The back plate provides an extension  70 , which fits into the wire spool during use.  FIG. 7  illustrates the spool mounting hub  16  of  FIG. 6  with the movable back plate  36  secured in the second locking recess  68  of the locking slot arrangement  48 . The threaded nut plate  38  tightens onto the left threads  50  in the indicated direction and provides circular indentations for the user to grip. As previously mentioned, the left threading ensures that the threaded nut plate  38  does not unthread during wire feeding. 
       FIG. 8  is a top plan view of the spool mounting hub assembly illustrating a braking system provided to keep the wire spool  18  from free wheeling when wire is not being fed to the welding operation. The wear plate  34  sits against the back wall  12 . The spool mounting hub  16  with the movable back plate  36 , the wire spool  18 , and the threaded nut plate  38  are mounted on the keyed shaft  14 . When the knurled nut  56  is turned in the indicated direction  72 , a lateral force, as indicated by reference numeral  74 , applies pressure to the keyed washer  52  that compresses the spring  54 . Spring compression leads to a force  76  against the wear plate  34  and the back wall  12 . This pressure prevents undesirable unwinding of the wire spool  18  when welding is not occurring. 
       FIG. 9  is an exploded view of an exemplary mounting system for small spools  78  in accordance with aspects of the present invention. The keyed shaft  14  extends outward from the wear plate  34  and contains a keyway  46  that extends approximately 75% of the way down the shaft  14 . The first washer  52  is first mounted in the keyway  46  onto the shaft  14 . The small spool  78  is mounted flat against the washer  52 . The second washer  52  is then mounted against the second side of the spool  78 . Finally, a spring  54  followed by a knurled nut  56  with threads  58  is mounted. A top plan view of this assembled mounting system for small spools  78  is illustrated in  FIG. 10 . 
     While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.