Patent Publication Number: US-9844828-B2

Title: Wire feeder assembly with motor mount

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the art of wire feeders used for welding. More specifically, it relates to a motor mount for a wire feeder used for welding. 
     BACKGROUND OF THE INVENTION 
     Some welding processes consume wire as they are carried out. Wire feeders provide wire to a welding gun, which feeds the wire to the arc. Power can be applied to the wire at the feeder, or at the gun. Wire feeders typically have a replaceable spool of wire from which the wire being fed to the arc is unwound. One or more drive rolls grip the wire and pull the wire from the spool, pushing it through a conduit to the gun and the arc. Some wire feeders feed the wire at a constant feed rate, but other wire feeders can vary the feed rate in response to the arc length and voltage. 
     Wire feeders can be made with different motors, and each motor type can have a unique hole mounting pattern. This makes manufacturing wire feeders more costly and complex, because the base assembly on which the motor is to be mounted must be different for each type of motor. Thus, a wire feeder that is modular, i.e, a wire feeder with a base assembly to which any of a group of different motors can be mounted, is desirable. 
     Wire feeders that have power applied to the wire at the feeder need to have electrical insulation or isolation between the wire drive and the electric motor. This complicates the attachment of the motor to the base, because screws and other parts are typically metal, and thus conductive. A wire feeder that provides electrical isolation or insulation between the motor and the drive assembly, yet is not complicated, is desired. 
     SUMMARY OF THE PRESENT INVENTION 
     According to a first aspect of the invention a wire feeder comprises a motor, a mounting plate, and a base assembly. The mounting plate is mounted to the base assembly, and the motor is mounted to the mounting plate. The base assembly included a gear and an insulating cap. The insulating cap is connected to the gear such that when the insulating hub rotates the gear rotates. The motor has a shaft extending through the mounting plate and into the insulating cap. The insulating cap and the mounting plate are comprised of an electrical insulating material, wherein the base assembly can be at a first potential and the motor can be at a second potential without current flowing therebetween. 
     One alternative provides an intermediate mounting plate. The intermediate mounting plate is mounted to the base assembly and the mounting plate is mounted to the base assembly by being mounted on the intermediate plate. The intermediate mounting plate is comprised of an electrical insulating material. 
     The intermediate mounting plate and/or the mounting plate is mounted to the base assembly using a plurality of screws, and/or the motor is mounted to the mounting plate using a second plurality of screws, in various embodiments. 
     Another alternative provides that the base assembly includes a gear hub with a hollowed interior that receives the motor shaft. The hollowed interior and the motor shaft have matching keys. The gear hub is connected to rotate with the motor shaft, and the insulating cap is connected to rotate with the gear hub. 
     The motor is one of a plurality of different sized motors, and each motor has the same size shaft and matching key, and the hollowed interior can receive any of the plurality in another embodiment. 
     The insulating cap has a non-cylindrical hollow interior in which the gear hub, which also has a non-cylindrical outer surface, is at least partially disposed, such that the gear hub rotates with insulating cap, and the gear hub is attached to rotate with the drive gear, in another embodiment. 
     The drive gear and insulating cap have a plurality of matching holes and screws extend through the matching holes to affix the insulating cap to the drive gear, in another embodiment. 
     Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the assembly of a wire feeder in accordance with the preferred embodiment; 
         FIG. 2  is a motor and drive roll assembly in accordance with the preferred embodiment; and 
         FIG. 3  is an exploded view of a motor and drive roll assembly in accordance with the preferred embodiment. 
     
    
    
     Before explaining at least one embodiment of the invention in detail it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. Like reference numerals are used to indicate like components. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the present invention will be illustrated with reference to a particular wire feeder assembly and a particular components, it should be understood at the outset that the invention could be used with other wire feeders and with other components. 
     A wire feeder, in accordance with the preferred embodiment, includes a motor and drive roll assembly that is modular in that it can receive any of a number of different motor types. It includes a mounting plate that has a number of different hole patterns used to mount motors. Also, it preferably includes an intermediate plate, to which the mounting plate is mounted. The combination of plates, which are made of electrical or insulating material, provide electrical isolation between the motor and the drive roll assembly. Moreover, the preferred embodiment provides a connection from the drive gear to the motor shaft that is also electrically insulating or isolating. Thus, the drive roll assembly can be at one potential (i.e, electrical potential), and the motor mounting at another, without current flowing therebetween. 
     Referring now to  FIG. 1 , an expanded perspective view, of a wire feeder  100  is shown. Wire feeder  100  includes a base assembly  101 , a motor  102 , a mounting plate  1 , and an intermediate mounting plate  4 . Base assembly, of a wire feeder, as used herein, includes the framework to which the inlet guide, outlet guide, motor, wire tensioners, etc. are mounted. Mounting plate, as used herein, is a plate to which another component is mounted, such as by screws, glue, rivets, etc. Intermediate mounting plate, as used herein, is a mounting plate to which another mounting plate is mounted, such as by screws, glue, rivets, etc. 
     Motor  102  is mounted to mounting plate  1 . Mounting plate  1  is mounted to intermediate mounting plate  4 . Intermediate mounting plate  4  is mounted to base assembly  101 . Mounting plate  1  and intermediate mounting plate  4  are made of hard plastic or other electrically insulating material. No metal screws extend from motor  102  to base assembly  101 . Thus, there is no electrical pathway created from motor  102  to assembly  101  by the mounting of motor  102 . Also plates  1  and  4  can provide thermal isolation. 
     Moreover, plate  1  includes a plurality of motor mounting hole patterns, each pattern being chosen for one particular motor type. For example, holes  21  are used for a three hole mount having a particular spacing. Holes  22  are used for a four hole mount, such as that of motor  102 . Thus, a number of different motor types can be mounted to plate  1 . Motor mounting hole pattern, as used herein, is a hole pattern for screws to mount a motor, i.e, the pattern of the mounting holes on the motor. 
     Screws  3  are inserted through holes  22  in plate  1 , and into motor  102 . Thus, motor  102  is mounted to mounting plate  1  using a particular one of the plurality of hole patterns on plate  1 . Plate  1  is mounted to assembly  101  using screws  11 , which extend through holes  10  and into assembly  101 . Bushings  5  prevent plate  4  from being compressed when screws  10  are tightened. Bushings  5  can be cast or sleeves. Screw, as used herein, includes any threaded fastener, tapered or cylindrical. Alternatively, plate  1  is mounted to intermediate plate  4  using screws  11  and holes  10  and intermediate plate  4  is mounted to base assembly  101  using screws  15  and holes  14 . 
     Wire feeder  100  may be assembled using a different motor with a different mounting hole pattern simply by using the matching pattern on plate  1 . Shaft  18  of motor  102  is inserted through motor shaft hole  19  of plate  1 . Alternatives provide for rotating plate  1  to align other hole patterns with other motors, using more or fewer screws, using and using other fasteners. Parts count and complexity is reduced, while providing electrical isolation between motor  102  and base assembly  101 . 
     Turning now to  FIGS. 2 and 3 , it is shown that shaft  18  of motor  102  is connected to rotate a gear  302  while maintaining electrical isolation. Gear  302  is mounted to an insulating cap  304  by screws  307 , which extend through holes  308  in gear  302  and cap  304 . Cap  304  is comprised of plastic or other electrically insulating material. In one embodiment screws  307  are also isolating. Cap  304  is rotatably mounted in bearings  305 , which are in base assembly  101 . Thus, as cap  304  rotates, gear  302  will rotate. Alternative embodiments provide for other ways to transfer the rotation of cap  304  to gear  302 , such as by a key or other matching structures. 
     Cap  304  has a hollow interior that is shaped to match the outer contour of a gear hub  306 . Gear hub  306  is disposed at least partially in cap  304 , and because their shapes are not cylindrical, as gear hub  306  rotates cap  304  rotates, and gear  302  rotates. Alternative embodiments provide for using different shaped gear hubs, or for screwing the hub to cap  304  or directly to gear  302 . Preferably, electrical isolation is maintained by using non-conductive materials. 
     The interior of gear hub  306  is hollow and shaped to receive motor shaft  18 . Preferably motor shaft  18  is keyed, and the inside of gear hub  306  is shaped with a matching key. Matching keys, as used herein, are the two parts of a key such as on a shaft and a hub receiving the shaft. Preferably, gear hub  306  receives a common shaft and key, such as a ½ inch shaft with a ⅛ inch key. Thus, any motor with this common key and shaft, and having one of the plurality of hole patterns on plate  1 , can be easily used with wire feeder  100 . One alternative provides that there be a number of different gear hubs  306  available, to receive different motor keys. Another alternative provides for more than one plate  1  to choose from, each with a plurality of mounting hole patterns thereon. This will further increase the modularity of wire feeder  100 . 
     A pair of wire tensioners  309 , a button spring  310  and a lock  303  can operate consistent with the prior art. 
     Numerous modifications may be made to the present invention which still fall within the intended scope hereof. Thus, it should be apparent that there has been provided in accordance with the present invention a wire feeder assembly that fully satisfies the objectives and advantages set forth above. Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.