Abstract:
A densely packed storage drum containing wire, and a method and apparatus for producing the same. The storage drum having an interior storage cavity into which wire is fed. The drum is supported on a turn table adapted to rotate and index the storage drum relative to a rotatable laying head which guides the wire into the drum. A capstan turning at a set rotational velocity pulls the wire and delivers the wire into the rotating laying head. As the laying head feeds the wire into the storage drum the difference in the rotational velocities of the capstan and laying head causes the formation of loops of wire in the storage drum. By varying the relative velocities of the capstan and the laying head, and rotating and indexing the storage drum relative to the laying head the wire can be deposited into the drum in layers, with each layer having a plurality of loops of a specified diameter circumferentially and eccentrically positioned about the interior cavity of the drum. Adjacent layers having different loop diameters and circumferential positions, producing a densely packed storage drum filled with wire having a uniform radial density.

Description:
This patent application is a continuation of application Ser. No. 09/212,830 filed on Dec. 16, 1998, which issued as U.S. Pat. No. 6,019,303 and incorporated herein by reference. 
    
    
     The present invention relates to the art of packaging small diameter welding wire into a bulk storage container or drum and more particularly to densely packing welding wire in a storage drum to increase the amount of wire which occupies the storage drum without affecting the ultimate use of the product which is payed out from the container for mass production welding. 
     BACKGROUND OF THE INVENTION 
     Small diameter welding wire is typically packed in a large container in a single spool which has a natural “cast.” This means that in the free state, the wire tends to seek a generally straight line condition. The invention will be described with particular reference to a natural cast type of welding wire stored as a large spool containing convolutions formed into layers of the welding wire. During use, the wire is ultimately payed out from the inside diameter of the spool through the upper portion of a container storing the spool. 
     When welding automatically or semi-automatically (including robotic welding), it is essential that the large amounts of welding wire be continuously directed to the welding operation in a non-twisted, non-distorted, non-canted condition so that the welding operation is performed uniformly over long periods of time without manual intervention and/or inspection. One of the difficult tasks in such welding is the assurance that the wire fed to the welding operation is fed in a non-twisted or low-twist condition so that the natural tendency of the wire to seek a preordained natural condition will not be detrimental to smooth and uniform welding. To accomplish this task, welding wire is produced to have a natural cast, or low-twist condition. This means that if a portion of the wire were cut into a long length and laid onto a floor, the natural shape assumed by the welding wire would be a generally straight line. This welding wire is wrapped into a spool in a large container (normally a drum) containing several hundred pounds of wire for automatic or semi-automatic welding. The natural tendency of the wire to remain in a straight or non-twisted condition makes the wire somewhat “live” when it is wrapped into the unnatural series of convolutions during placement in the container, resulting in distorting the wire from its natural state. For that reason, there is a tremendous amount of effort directed to the concept of placement of the wire within the container in order that it can be payed out to an automatic or semi-automatic welding operation in a low-twist condition. If the wire is not loaded correctly within the container, massive welding operations, which can consume a large amount of welding wire and a substantial amount of time, can be non-uniform and require expensive reprocessing. This problem must be solved by the manufacturers of welding wire, since they package the welding wire in the large spools which are intended to be payed out for the automatic or semi-automatic welding. 
     In recent years, there has been a trend toward even larger packages with a larger stock of welding wire. The large packages are intended to reduce the time required for replacement of the supply container at the welding operation. The increased demand for ever-larger supply containers is contrary to and further reduces the ability to smoothly withdraw the welding wire without disturbing the natural flow of the welding wire or twisting the welding wire with adjacent convolutions. Thus, a large volume high capacity storage supply container for welding wire spools must be constructed so that it assures against any catastrophic failure in the feeding of a wire to the welding operation. The pay-out or withdrawing arrangement of the container must be assured that it does not introduce even minor distortions in the free straight flow of the welding wire to the welding operation. The first step in assuring that no minor distortions exist is placement of the welding wire within the container in a manner which will allow withdrawal of the wire from the container in the preferred state. 
     The welding wire stored in the supply container is in the form of a spool having multiple layers of wire convolutions laid from bottom to top. The inner diameter of the spool is substantially smaller than the diameter of the container. Due to the inherent rigidity of the welding wire itself, the convolutions forming the layers are continuously under the influence of a force which tends to widen the diameter of the convolutions. In order to account for this tendency, the welding wire is laid within the supply container in preferred loop diameters, the loop diameters being smaller than the inner diameter of the supply container. Typically, the loop diameter is at least 15% less than the inner diameter of the drum. 
     The welding wire is drawn from the manufacturing process and fed over a series of dancer rollers and pulled along by a capstan adjacent the storage container. From the capstan, the welding wire is fed into a rotatable laying head, which is generally a cylindrical tube having an opening at the bottom or along the cylinder adjacent to the bottom. The wire extends through the tube and out the opening, whereupon it is placed into the storage container. 
     The laying head extends into the storage container and rotates about an axis generally parallel to the axis of the storage container. The wire being fed into the laying head by the capstan is fed at a rotational velocity different than the rotational velocity of the laying head. The ratio between the rotational velocity of the laying head and the rotational velocity of the capstan determines the loop size diameter of the wire within the storage container. As the wire is laid within the storage container, the weight thereof causes the storage container to gradually move downward. As the storage container moves downward, the laying head continues to rotate, thus filling the storage drum to its capacity. The storage drum is incrementally rotated a fraction of one revolution for each full loop of welding wire placed within the storage drum. This causes a tangential portion of the welding wire loop to touch a portion of the inside diameter of the storage container, while the opposite side of the loop is spaced a distance from the side of the container. This is accomplished by moving the laying head off the center line of the storage container by one-half the difference between the loop diameter and the diameter of the storage container. 
     Accomplishment of this prior art method of loading a storage container is best shown in FIG.  6 . This method of loading storage drums with welding wire is important to the effective withdrawal of the welding wire during the welding process. However, as can be seen from FIGS. 7 and 8, this process also results in a loose density packing of the welding wire within the storage container. Depending on the diameter used relative to the storage container, the wire has a higher density along the edge portion of the storage container versus the inside diameter of the spool itself adjacent the spool cavity. This is caused since more wire is placed along the edge portions of the container than is placed along the spool cavity. While the net effect results in welding wire being able to be pulled from the container without substantial problems of tangle or twist, the low density packing means that interruptions in the welding process are more frequent. There is, therefore, greater down time for the welding operation and greater labor costs, since replacement of the supply container at the welding operation and manual intervention in the welding operation is necessary. 
     SUMMARY OF THE INVENTION 
     The present invention advantageously provides an improved method and apparatus of densely packing welding wire in a storage container, which overcomes the disadvantages of the prior art method and apparatus arrangements. 
     More particularly in this respect, the invention is used to package more welding wire in smaller but more densely packed containers, without affecting the ability to smoothly withdraw welding wire during automatic or semi-automatic welding processes. The machine for densely packing welding wire comprises a capstan for pulling the welding wire from the manufacturing process, a rotatable laying head upon a first axis for receiving the wire from the capstan, and a turntable which supports a welding wire storage drum. The welding wire is packaged within the storage drum by rotating the laying head at a first rotational velocity and rotating the capstan at a second rotational velocity in order to determine the loop diameter. The turntable is rotated about an axis which, in a preferred embodiment, is parallel to the first axis, at a third rotational velocity. Generally, for each loop of welding wire placed within the storage drum, the turntable rotates a fraction of one revolution, thus causing only a small portion of the circumference of the loop to contact the inner surface of the storage drum. By rotating the turntable only a fraction of one revolution, it is ensured that a subsequent loop placed within the storage drum will contact the interior surface of the storage drum at a second position along the interior of the storage drum and adjacent the first position of the preceding loop. Importantly, an indexing apparatus allows the storage drum and rotatable laying head to be moved relative to the other in sequential steps during loading of the wire within the storage drum. Preferably an indexer is used which causes the rotatable laying head to place wire in the storage drum from a different position within the storage drum, many of the disadvantages of the prior art can be overcome. Specifically, welding wire can be placed more densely within the container by avoiding placement of the wire from the same axis of rotation within the container. The invention is even better enhanced by intermittently changing the loop diameter of the wire within the container in combination with the indexing step. The net effect is the production of striated layers of welding wire within the container, each layer having a maximum density at a different radial position within the container than the adjacent layer. The indexing step and/or the changing of loop diameter ensures that a container of welding wire is more densely packed than prior art arrangements and thus more welding wire is placed within the same volume container. 
     In a preferred method of the invention, a capstan for densely packing welding wire in a storage drum is provided above the storage drum and is rotated at a set rotation for pulling the welding wire from a manufacturing process. The laying head is provided on a first axis which is preferably perpendicular to the axis about which the capstan rotates. The laying head rotates at a rotational velocity different than the capstan. The ratio of the rotational velocity of the capstan versus the rotational velocity of the laying head determines the loop size placed within the storage drum. Wire is fed from the capstan to the laying head, the laying head being provided and inserted within the storage drum. The storage drum is supported on a turntable which rotates a fraction of a revolution for every singular full revolution of the laying head. The laying head and the turntable preferably rotate about parallel axes. Periodically as the loops are being placed, one of the wire drum and the laying head are caused to index from a first position to a second position longitudinally displaced from the first position and along the line generally perpendicular to the rotational axis of the turntable. In combination with the indexing step, the first or the second rotational velocity may also be changed, which changes the ratio and thus changes the loop size diameter being placed within the storage drum. Further, in accordance with a preferred embodiment, the indexing step includes moving the wire drum relative to the first axis as a function of the number of the rotations of the turntable. This advantageously provides the striated or layered effect within the container which allows for the dense packing. 
     It is thus an outstanding object of the present invention to provide a welding wire storage drum with a significantly greater amount of welding wire than disclosed by the prior art. 
     It is yet another object of the present invention is to provide a packaged welding wire storage drum which results in less down time and less labor requirements during automatic and semi-automatic welding processes. 
     Still another object of the present invention is to provide a welding wire storage drum capable of storing more welding wire in less space, thus requiring less warehouse space than heretofore available. 
     Yet another object of the present invention is to provide an apparatus for densely packing welding wire in a storage drum which results in more densely packed storage containers. 
     A further object of the present invention to provide a method for densely packing welding wire in a storage drum without affecting the ability to smoothly withdraw the welding wire during the welding process. 
     It is a further object of the present invention to reduce the down time and labor costs associated with changing welding wire storage drum containers during a welding process. These and other objects of the invention will become apparent to those skilled in the art upon reading and understanding the detailed description in the following section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail and illustrated in the accompanying drawings which form a part hereof and wherein: 
     FIG. 1 is an elevation view illustrating the packaging system according to the present invention; 
     FIG. 2A is an elevation view showing the bottom half of FIG. 1; 
     FIG. 2B is an elevation view showing the top half of FIG. 1; 
     FIG. 3 is a plan view taking along line  3 — 3  of FIG. 2A; 
     FIG. 4 is an elevation view of the turntable system taken along line  4 — 4  of FIG. 2A; 
     FIG. 5 shows a storage drum filled with welding wire in accordance with the present invention; 
     FIG. 6 is a plan view showing the method of placement of welding wire as taught in the prior art; 
     FIG. 7 is a partial elevation view, in cross-section, showing the density variation of packed welding wire in the prior art; 
     FIG. 8 is a partial elevation view, in cross-section, showing the density variation of packed welding wire in the prior art; 
     FIG.  9 A and FIG. 9B show the steps in forming a single loop diameter layer in accordance with the present invention; 
     FIG.  10 A and FIG. 10B are an additional example of the steps in forming a single loop diameter layer in accordance with the present invention; 
     FIG. 11A is a schematic illustration of the method of forming the loop diameter shown in FIGS. 9A and 9B; 
     FIG. 11B is a schematic illustration showing the method of forming the loop diameter shown in FIGS. 10A and 10B; 
     FIG. 12 is a partial elevation view, in cross-section, showing the affect of alternating layers of welding wire shown in FIGS. 9-11; and, 
     FIG. 13 is a partial elevation view, in cross-section, showing another example of different layers of welding wire. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings, wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting same, FIG. 1 shows a drum winding system  10  which draws a continuous welding wire  11  from a manufacturing process (not shown). Welding wire  11  is drawn by a capstan  12  driven by a wire feed motor  14  connected to a pulley  16  which drives a belt  15 . As can be seen, the wire is drawn over a series of rolls and dancer rolls  17   a ,  17   b  and  17   c  which serve to maintain tension to welding wire  11  between the manufacturing process and capstan  12 . As can be seen from FIGS. 1 and 2B, welding wire  11  is wrapped about 270° about capstan  12 . This provides proper friction and drive capacity to draw welding wire  11  across the dancer rolls  17   a - 17   c . Welding wire  11  is fed into a rotatable laying head  21  which is suspended from a winding beam  22 . Rotatable laying head  21  rotates within a bearing housing  23  which is suspended from winding beam  22 . Rotatable laying head  21  includes a laying tube  24  and a journal portion  25  extending therefrom and supported for rotation by a flange  26  and a top and a bottom bearing  27  and  28  located at the top and bottom ends, respectively, of bearing housing  23 . It will be appreciated that journal portion  25  includes both an outer cylindrical surface  31  for contact with bearings  27  and  28  and an inner cylindrical surface  32  defining a hollow shaft interior which allows welding wire  11  to pass from capstan  12  to laying tube  24 . 
     A pulley  33  is keyed into the outer cylindrical surface  31  of journal portion  25  below bearing housing  23 . A corresponding pulley  34  extends from a shaft  35  of a layer drive motor  36 . A belt  37  connects pulleys  33  and  34  in order that layer drive motor  36  drives journal portion  25  and correspondingly drives rotatable laying head  21 . 
     The control panel  41  directs the speed of layer drive motor  36  and wire feed motor  14  as well as coordinating the ratio between the speed of the two motors. The motor speed affects the rotational velocity of laying head  21  and the rotational velocity of capstan  12 . It will be appreciated that the ratio between the laying head rotational velocity and the capstan rotational velocity determines a loop size diameter of welding wire  11  as will be described below. 
     Laying tube  24  includes an outer cylindrical surface  42 , an inner cylindrical surface  43 , and a generally closed upper end  44  having inner and outer surfaces  45  and  46 , respectively. A small hole  47  centered about a centerline axis A of laying tube  24  extends between inner surface  45  and outer surface  46 . The lower end of journal portion  25  extends through small hole  47 , is supported by a small flange  51  at the extreme lower end of journal portion  25  and tack welded in place. The bottom end of laying tube  24  includes a ring  52  extending about the circumference of the lower end of laying tube  24 . Ring  52  has an opening  53  through which welding wire  11  passes from laying tube  24  during the packing operation. 
     A turntable  54  is supported for rotation on a turntable support  55 . Turntable support  55  includes a guide track  56 , a force cylinder  57 , and an L-shaped beam portion  58 . As mentioned above, turntable support  55  allows rotation of turntable  54  thereupon, and specifically upon a horizontal beam  61  of L-shaped beam portion  58 . It will be appreciated that as the weight of welding wire  11  is placed within storage drum  62 , a vertical beam portion  63 , which is attached to the rubber guide wheels  64 , rides downward on guide track  56 , which is shown as an H-beam. Thus, L-shaped beam portion  58  rides downward on guide track  56  while storage drum  62  is filled. 
     Vertical beam portion  63  includes a finger  65  which extends outwardly therefrom and is pivotally attached at pin  67  to an outward end  68  of a rod  71  which is part of a pressurized cylinder assembly  72 . Pressurized cylinder assembly  72  includes a pressurized cylinder  73 . It will be appreciated that cylinder  73  is pressurized such that when storage drum  62  is empty, cylinder  73  is at equilibrium and L-shaped beam portion  58  is at its highest point on guide track  56 . As storage drum  62  is filled with welding wire  11 , the additional weight placed on turntable  54  causes piston rod  71  to extend downward as shown by arrow X in a controlled descent down guide track  56 . The pressure within cylinder  73  is based upon a predetermined weight to pressure ratio. The controlled descent allows welding wire  11  to be placed within storage drum  62  from the bottom of storage drum  62  adjacent turntable  54  to the top lip of storage drum  62 . Thus, in the preferred embodiment, rotatable laying head  21  does not move in a vertical direction but instead turntable  54  moves in the vertical direction which is parallel to the centerline axis A of laying tube  24 . 
     Turntable  54  is driven for rotation in a manner similar to laying tube  24 . A bearing housing  84  is mounted on horizontal beam  61  of L-shaped beam portion  58 . A journal portion  85  extends downwardly from turntable  54  and is allowed to freely rotate by means of the bearings  86  and  87 . In accordance with the present invention, journal portion  85  is a cylinder which has an outer cylindrical surface  88  and an inner cylindrical surface  89  for purposes which will be described later. A cogbelt pulley  92  is keyed to the bottom end of journal portion  85 . Cogbelt pulley  92  is connected to cogbelt pulley  93  by a belt  94 . Cogbelt pulley  93  is driven by a turntable motor  95  through a gearbox  96 . Turntable motor  95  is geared down substantially from laying tube  24  in order than turntable  54  only rotates one fraction of a single revolution relative to a full revolution of laying tube  24 . 
     As can be best seen from FIG. 2A, FIG.  3  and FIG. 4, turntable  54  includes a bottom platform  101  which is driven for rotation by a top end key assembly  102  of journal portion  85 . As best seen in FIG. 4, a slide table  103  is mounted on bottom platform  101  of turntable  54  by way of a large keyway  104  cut into the bottom end  105  of slide table  103 . A key  106  of bottom platform  101  retains slide table  103 . Slide table  103  is capable of movement relative to bottom platform  101  by the sliding of keyway  104  on key  106 . It will be appreciated that key  106  and keyway  104  can be coated with a relatively frictionless surface such as nylon or the like. Additionally, the bearing surface  107  of key  106  can be provided with a track and ball bearings or other type of bearings (not shown) which facilitates ease of movement between slide table  103  and bottom platform  101 . 
     Movement of slide table  103  is caused by an indexer working in conjunction with slide table  103 . Preferably, the indexer is a piston and cylinder assembly  110  which depends downwardly from turntable  54 . Piston and cylinder assembly  110  includes two generally identical rod and pistons  111  and  112 , respectively, which are commonly connected by a drive rod  114 . Each of rod and pistons  111  and  112  are spaced apart an equal distance from journal portion  85  of turntable  54 , and generally parallel to the direction of movement between key  106  and keyway  104  as shown in FIG.  3 . 
     Rod and piston  111  will now be described. It will be appreciated that rod and piston  112  is identical and is numbered identically in the drawings. Rod and piston  111  includes piston portion  115  pivotally attached to bracket  116  which depends downwardly from bottom platform  101 , by a pivot pin  117 . Rod portion  118  extends from the opposite end of piston portion  115  to a block  121  which retains drive rod  114  therein. In turn, drive rod  114  extends generally perpendicular to rod portion  118  and is connected to identical block  121  extending from rod and piston  112 . Between blocks  121 , drive rod  114  is connected to a lever  122  at the lever lower end  123 . At a middle portion  124  of lever  122 , lever  122  is pivotally connected by a pin  125  to a bracket  126  extending from the bottom end of bottom platform  101 . At an upper end portion  127  of lever  122 , lever  122  is pivotally connected to slide table  103  by a pin  128 . As can be best seen in FIG. 4, lever  122  is permitted to extend through bottom platform  101  to slide table  103  through aligned slots  131  and  132  in each of bottom platform  101  and slide table  103 , respectively. Rod and pistons  111  and  112  are each driven equally by air. An air supply (not shown) is connected to air supply tube  133  at the bottom of journal portion  85 . The inner cylinder surface  89  serves as an air passageway through which air supply is fed upwards to air supply hoses  134  and  135  (seen in FIG. 3) which are then connected to cylinder inlet  136 . With the above arrangement, it will be appreciated that an air supply is capable of driving rod portion  118  of rod and pistons  111  and  112 , which in turn drives lever  122  to move slide table  103  and keyway  104  in a horizontal direction relative to key  106  and bottom platform  101 . The arrangement accomplishes this sliding movement without affecting the ability of turntable  54  and bottom platform  101  to rotate. A fully packed storage drum  62  is shown in FIG.  5 . 
     The invention thus allows a storage drum  62  mounted on turntable  54  and specifically mounted with the clips  137  to slide table  103  be filled in accordance with the method as shown in FIGS. 9-13. As can be seen, welding wire  11  is placed within storage drum  62  by rotation of laying tube  24  about axis A. The rotation of laying tube  24  is shown by arrow C in FIGS. 9-11. It will be appreciated that laying tube axis A is offset from the centerline axis B of storage drum  62 . 
     In one example, shown in FIGS. 9 and 10, a 20 inch storage drum  62  is used. With each single 360° revolution of laying tube  24 , a 16.5 inch diameter loop of wire  11  is placed. Simultaneously, turntable  54  is caused to rotate a fraction of one revolution, preferably between one and two degrees, in the direction of rotation as shown by arrow M. The pattern developed within storage drum  62  is shown in FIG.  9 B. After about 9-10 revolutions of storage drum  62 , the loop diameter is changed. Using control panel  41 , the relative rotational velocities of capstan  12  and rotatable laying head  21  are changed to change the loop diameter. As shown in FIGS. 10A and 10B, a 15.5 inch loop is placed in a full 360° layer, defined as one full revolution of turntable  54  during which laying tube  24  rotates about 323 times to place 323 15.5 inch loops. If the singular 16.5 inch coil (FIGS. 9A and 9B) or 15.5 inch coil (FIGS. 10A and 10B) were continued from the bottom to the top of storage drum  62 , the cross-sectional pattern shown in FIG. 7 (for 16.5 inch coil) or FIG. 8 (for 15.5 inch coil) would be developed. The cross-sections of FIGS. 7 and 8, developed using the rotational method shown in FIG. 6, show a high density of welding wire at the extreme outer edges of storage drum  62  with less density towards the centerline axis B of storage drum  62 . 
     The present invention, and specifically rod and pistons  111  and  112 , allow movement of centerline axis B of storage drum  62  relative to stationary centerline axis A of laying tube  24 . As shown in FIGS. 11A and 11B, this movement, coupled with an adjustment of the ratio of the rotational velocity between capstan  12  and laying tube  24 , changes the laying pattern within storage drum  62 . Changing the loop diameter of welding wire  11  alone, without a corresponding shift in the centerline of storage drum  62 , is not preferred, since the loop diameter should be sized to tangentially touch the inner surface of storage drum  62  at at least one point. Since welding wire  11  is somewhat “live,” it will seek the inner surface even if not intentionally laid there. If its placement is less controlled, smooth withdrawal of the welding wire is not assured. The invention allows patterns such as those in FIGS. 9B and 10B to be developed. 
     As shown in FIGS. 12 and 13, the invention uniquely provides for different loop diameters of welding wire  11  to be placed within storage drum  62 . The placement of alternating layers of welding wire  11  having different loop diameters significantly increases the packing density within storage drum  62 . It has been found that the packing density can be increased by upwards of 50% within the same volume storage container by placing 50% more wire within the same drum. FIG. 12 shows the example described in FIGS. 9-11, i.e. layers of welding wire within a storage drum  62  of 20 inch diameter. As can be seen, alternating layers of 16.5 inch loop diameter and 15.5 inch loop diameter are placed within the 20 inch drum. Since each loop diameter has a different density at points equidistant from the centerline of the drum, the differing densities and weights act to pack welding wire  11  more tightly within drum  62  and less void space is created within the same volume. FIG. 13 shows a second example with a 23 inch diameter drum in which a loop diameter is varied between 17.25, 18.25 and 19.25 inches. It will be appreciated that other patterns can be developed. The invention allows that the capacity of each storage drum  62  is increased by upwards of 50% from the prior art method and apparatus. It will be appreciated that the above examples can be modified. The optimum density is determined by the diameter of the drum and the loop diameter. 
     The invention has been described with reference to the preferred embodiment. Obviously, modifications and alterations other than those discussed herein will occur to those skilled in the art upon reading and understanding the specification. It is intended to include all such modifications insofar as they come within the scope of the invention.