CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a PCT International Application, which daims tee benefit of United States Provisional Patent Application No. 62/959,330, filed January

10, 2020.

FIELD OF THE INVENTION

[0002] The present disdosure relates to a conduit espedal!y adapted for use in a weld wire dispensing system or as a control cable conduit, in particular, the present disdosure relates to a spring type wire guide conduit constructed of coiled wire having an oval or elliptical cross-section and further featuring locally hardened surface areas on the inside of the conduit to improve wire flow through tee conduit

BACKGROUND

[0003] Metal Inert Gas (MIG) welding also referred to as “wire-feed” or Gas Metal Arc Welding (GMAW) utilizes heat from an electrical arc to melt a consumable electrode to form a weld on a workpiece, in this description, these systems will be collectively described as MIG welding systems. A MIG welding system typically indudes a power supply, a gas supply and an electrode supply connected to a welding device or welding gun. A ground cable is used to connect the workpiece to the power supply. The welding device generally indudes a handle, a gooseneck and an end assembly. The welding system can be automatic or semi-automatic and may be manually or robotically controlled. The electrode and gas are coupled through a conduit in the handle and the gooseneck to tee end assembly of the welding device.

The electrode extends through the contact tip of the end assembly and tee gas moves around the contact tip in the nozzle of the end assembly to shield the weld site. When the welding device is activated, foe electrode is fed through foe contact tip toward foe workpiece and the gas is directed through the nozzle to flood the weld site. When the electrode is placed adjacent to or in contact with foe workpiece, the electrode completes an electrical circuit between the power supply and the workpiece, allowing current to flow through the electrode to foe workpiece. The current produces an arc between the electrode and the workpiece. The heat of the arc melts the electrode and foe workpiece in foe region surrounding the arc, creating a weld puddle. The gas flowing out the nozzle shields the weld puddle from atmospheric gases and outside contaminants. The type of shielding gas used in MIG welding varies depending on many factors. Noble or inert gases such as Argon are often used. However, Carbon

Dioxide (CO ₂ ) and a mixture of gases such as CO ₂ and Argon are also used. Once foe electrode is moved away from the workpiece, the electric circuit is broken and the weld puddle cools and solidifies, forming a weld.

[0004] In typical MIG welding systems, a flexible wire guide conduit is used to transport foe flexible electrode wire from a storage bin, typically from a wire spool, through a wire feeder drive device and through the flexible wire guide conduit to the torch. Flexible conduits are generally formed by coiling a wire to produce a hollow passageway through which the electrode wire moves. These types of conduits are often referred to as spring type or spring liner conduits.

[0005] In the past, weld wire conduits used in weld wire dispensing systems have been constructed using wire having a rectangular cross-section. However, in instances where the weld torch cable or weld wire conduit is bent or flexed, the edges of the wire forming the conduit are exposed. The exposed edges of the wire forming foe conduit damages the surface of the weld wire as foe weld wire is pushed ex pulled through the conduit. The sharp edges of the conduit wire can "shave" or cut the weld wire as tire weld wire is moved through foe passageway of the conduit. The sharp edges also increase friction between the weld wire and the conduit as the weld wire is moved through the weld wire conduit

[0006] The higher friction results in more force being required to move the weld wire through foe conduit, which decreases foe overall efficiency of foe weld wire dispensing system, and can lead to binding and failure of the weld wire delivery system. Damage to the surface of the weld wire caused by the exposed edges of foe wire forming the conduit also results in tire shavings and residue collecting in the inner passageway of the conduit. In some instances, the build-up of shavings and residue eventually prevents the weld wire from being pulled or pushed through the conduit. In addition, as the shavings and residue build-up in the conduit, they significantly increase friction between foe weld wire and the conduit and thus increase the force needed to push or pull foe weld wire through foe conduit. The increase in friction also causes drive roll wire slippage in foe weld wire dispensing system, as well as bum- back in the system. The shavings and residue can also lead to the weld wire being stuck inside the torch contact tip.

[0007] Wire guide conduit conduits are also constructed of wire having a circular cross-section. However, it is difficult to provide a protective coating on only the inner surface of the conduit constructed of round wire. Round wire tends to rotate in dies; therefore, it is extremely difficult to set a desired surface of the round wire in a continuous position as necessary to provide coating on only foe inner surface of foe conduit which contacts the electrode wire.

[0008] The present applicant has devised improvements in the area of flexible wire conduits and have introduced the use of elliptical or non-round wire to form weld wire conduits. Wire guide conduit conduits based on such wire shapes have resulted in significant improvements in the performance of wire guide conduit conduits for welding. Such configurations are described and claimed in Applicant's previously issued US Patent Nos. 9,056,367 and 9,687,932, which are hereby incorporated by reference.

[0009] In an effort to improve weld wire guide conduit performance, it is known to provide surface coatings such as lubricants to the wire forming the wire guide conduit.

An example is a coating of tungsten sulfide. Although such treatments are beneficial, they tend to have a limited operational lifespan as the lubricant materials dissipate over operational use of foe wire guide conduit.

[0010] Despite the numerous improvements in the art, there remains a continued need to reduce friction of electrode wire fed to the wire guide conduit and increase their service life. In order to form the tightly wound wire guide conduit conduits, relatively soft metals are used such as 1040 carbon steel. A disadvantage of foe fbrmability requirement is the relative softness of such metal alloys. Softness leads to wear over time as foe electrode wire is fed through the wire guide conduit, especially where relatively tight bends are present. Wear on fee inside surfaces of the wire forming foe wire guide conduit leads to shaving of electrode wire as mentioned previously, and even complete cutting through of the wire guide conduit. Further, such wear tends to increase friction forces acting on foe electrode wire as it moves to foe wire guide conduit and causes an enlargement of the internal passageway of the wire guide conduit which can lead to buckling of the electrode wire; again resulting in decreased efficiency of electrode wire transfer.

[0011] The above referenced design challenges related to the transfer of MIG welding electrode wire are also encountered in the field of control wires used for many industrial and commercial applications. For example, control cables are widely used for bicycles for brake and derailleur gear selection control, motorcycles and motor vehicles as clutch and transmission cables, and in other automotive applications for controlling movable panels such as HVAC control doors, etc. Coiled spring type control cables are further used in additional widespread applications.

[0012] In view of the foregoing there remains a need for a wire guide conduit having longer life capabilities and improved performance especially as related to friction and service life associated with the transfer of a wire electrode or control cable.

BRIEF SUMMARY OF THE INVENTION

[0013] In accordance with foe present invention a wire guide conduit is provided constructed from a coiled wire having an oval or elliptical cross-section. Before the wire is formed into the coil, a surface heat treatment process is performed to create locally hardened regions along the wire of the wire guide conduit. Such locally hardened regions can be provided by, for example, laser treatment or other directed energy processes which cause local heating of foe surface of foe wire to create such hardened regions. These hardened regions are intentionally created to be at discrete isolated locations as to not interfere with the formabi!ity of the wire which is adversely affected by increasing hardness.

[0014] In the manufacturing process for forming the wire guide conduit the oval wire is treated by a laser (or other directed energy process) to create dots or stripes of locally hardened regions and foe wire is thereafter rolled into a wire guide conduit with foe locally hardened regions facing foe inside surface of the conduit As the electrode wire moves through such a wire guide conduit, the locally hardened areas act essentially as wear bars or hard points of contact for supporting the electrode wire as it moves through foe conduit. Wear of foe conduit wire is reduced in these locally hardened regions. This leads to improved longevity and reduced friction during use. Surface coatings and lubricants such as mentioned previously may also be used in conjunction with the present invention. The wire guide conduit in accordance with this invention may also be used as a control cable conduit to allow an actuation cable to be connected between two points.

[0015] According to an aspect, a wire guide conduit adapted for allowing movement of a core is provided. The conduit includes a wire coiled in a helical manner to define the conduit and form an internal passageway of the conduit, the passageway defining a longitudinal axis, wherein the wire has a cross-section with a major axis and a minor axis, wherein a thickness of the wire along the major axis is greater than a thickness of the wire along the minor axis, wherein the wire is coiled in the helical manner to present the major axis generally parallel with the longitudinal axis of toe passageway, the passageway adapted for receiving the core, wherein the wire has a straight configuration prior to being coiled and includes periodically spaced locally hardened regions having a surface hardness greater than areas of the wire outside of the locally hardened regions, wherein the locally hardened regions are disposed on an inside surface of the conduit fating the internal passageway when the wire is coiled in toe helical manner.

[0016] In one aspect, the wire consists of a single wire coiled in the helical manner.

[0017] In one aspect, the wire has a generally elliptical cross-section.

[0018] In one aspect, the internal passageway of toe wire guide conduit defines an inner diameter, and wherein the inner diameter is constant along substantially the entire length of toe conduit

[0019] In one aspect, the internal passageway of the wire guide conduit defines an inner diameter, and wherein toe inner diameter is adapted to closely receive the core in toe form of a wire having a circular cross-sectional shape. [0020] In one aspect, the wire has opposed first and second sides on opposite sides of tiie major axis and extending along the major axis and wherein the locally hardened surfaces are provided on only the first side of the wire so that when the wire is coiled to form the wire guide conduit, the first side of the wire forms the inner passageway of the conduit so that the hardened surfaces are provided only CHI the inner passageway of the conduit.

[0021] In one aspect, the wire guide conduit is configured to be used in a weld wire dispensing system with the core in the form of a welding electrode wire.

[0022] In one aspect, the locally hardened regions form a pattern along the wire when the wire is in the straight configuration.

[0023] In one aspect, locally hardened regions are equally spaced when the wire is in the straight configuration.

[0024] In one aspect, the pattern includes one of a series of dots, a series of stripes, a series of altematingly inclined stripes, a series of inter-locking circles along the length of the wire, or a series of interlocking circles forming stripes across the surface of the wire.

[0025] In one aspect, the locally hardened region is disposed within a profile of the wire when the wire is in a straight configuration such that the locally hardened region does not substantially project relative to adjacent non-hardened regions.

[0026] In one aspect, an outside surface of the wire guide conduit does not include any locally hardened regions.

[0027] In one aspect, the locally hardened regions are disposed at various circumferential and longitudinal locations on the inside surface of the conduit.

[0028] In one aspect, the locally hardened regions do not extend fully across the wire along the major axis. [0029] According to another aspect, a method for forming a wire guide conduit forming an internal passageway for the passage of a core. The method indudes providing a wire in a straight configuration, the wire having a cross-section forming a major axis and a minor axis, wherein a thickness of the wire along the major axis is greater than a thickness of foe wire along the minor axis; wherein foe wire has opposed first and second sides on opposite sides of the major axis and extending along the major axis and applying an energy beam to foe first side of foe wire causing localized heating of a surface of the first side and creating discrete and separated areas of locally hardened regions, and coiling the wire having foe locally hardened regions such that foe major axis of the wire is aligned with a longitudinal axis defined by the conduit in a manner to present the locally hardened regions toward foe internal passageway to form the wire guide conduit

[0030] In one aspect, foe core is an electrode wire and foe wire guide conduit is used for conducting foe electrode wire toward a MIG welding torch.

[0031] In one aspect, foe energy beam is a laser producing a beam directed onto foe first surface of wire.

[0032] In one aspect, the beam is tightly focused and moves longitudinally relative to foe wire during application of the beam, wherein the beam is a continuous wave or pulsed.

[0033] In one aspect, as foe beam moves longitudinally relative to the wire, the beam is maintained at a constant lateral orientation relative to foe cross-section axis of foe wire during application of foe beam or foe beam moves laterally relative to foe wire during application of foe beam. [0034] In one aspect, the locally hardened regions are disposed at various circumferential and longitudinal locations on the inside surface of the conduit and no locally hardened regions are disposed on the outside surface of the conduit.

[0035] Additional substance and advantages of the present disclosure will become increasingly apparent by reference to the following drawings and the description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a side cutaway view of a spring type wire guide conduit positioned in a welding torch.

[003η Figure 2 is a side elevational view of a wire guide conduit showing a protruding electrode wire.

[0038] Figure 3 is a cross-sectional view of a wire guide conduit according to the present disclosure.

[0039] Figure 4 is an end view of the conduit showing the inner passageway of the wire guide conduit.

[0040] Figure 5 is a cross-sectional view of the wire used for forming the wire guide conduit.

[0041] Figure 6 is an elevational view of wire for forming the wire guide conduit showing locally hardened regions along a surface of the wire.

[0042] Figure 7 is a diagrammatic illustration of a laser surface treatment system.

[0043] Figures 8-11 show alternate embodiments of patterns of locally hardened regions of wire for forming a wire guide conduit.

[0044] Figure 12 is a side elevational view of a wire guide conduit according to the present disclosure used as a control cable. DETAILED DESCRIPTION OF THE INVENTION

[0045] Referring to Figure 1 , a representative welding torch 20 is illustrated for use in a MIG welding process. Welding torch 20 includes flexible wire guide conduit 10 formed of a coiled wire 12. In the MIG welding process, electrode wire 16 is fed through wire guide conduit 10 to protrude from torch tip 22. Electrode wire 16 can also be generally characterized as a core.

[0046] Wire 12 for forming wire guide conduit 10 has, for example, an essentially oval or elliptical cross-sectional shape (which may also be referred to as non-round).

In this description, such cross-sectional shapes for wire 12 will be referred to collectively as having an oval or non-round cross-sectional shape. While toe description of non-round may be used, it will be appreciated that the wire 12 may still have a rounded shape with rounded edges (for example excluding sharp edges such as those arising from a rectangular or square cross-section), and that non-round can refer to non-symmetrical shapes as well as symmetrical shapes. Accordingly, reference to non-round may also be used to signify a cross-section that is generally non-circular.

[0047] For example, as shown by Figure 5, wire 12 of a representative shape in cross-section forms a major axis A-A and a minor axis B-B. it is understood that wire

12 does not have a circular cross-sectional shape and that the width of wire 12 along major axis A-A is greater than the width of the wire along minor axis B-B. In general, the cross-sectional shape of the wire 12 is such that the wire 12 does not have any sharp comers or flat edges. Wire 12 used to form the conduit 10 can be constructed of any material well known in the art which is used to construct conduits. For example, the wire 12 may be constructed of 1040 carbon steel and formed by drawing a source material through a forming die or roller forming tools. The non-round cross-section of the wire 12 permits the wire 12 to be wound or coiled in a controlled manner to define the conduit 10.

[0048] When wire 12 is coiled to form wire guide conduit 10, the wire is oriented such that major axis A-A is aligned along the longitudinal axis 25 of central passageway 24 of the wire guide conduit, as shown in Figure 3. Figure 4 is an end view of wire guide conduit 10 showing in section a view of oval wire 12. As shown in

Figure 4, toe longitudinal axis 25 appears as a dot, and a cross-section of the wire 12 is shown. The orientation of the cross-section of Figure 5 is similar to that of Figure 3, such that axis B-B is generally aligned transverse to the passageway of the conduit

10 when the wire 12 is coiled.

[0049] As shown in Figure 5, the non-circular or non-round wire 12 with the major and minor axis also has a width along axis A-A that is greater than a height along axis

B-B. Thus, upper and lower surfaces of toe wire 12 in Figure 5 are generally longer than the side surfaces.

[0050] One advantage of using non-round wire 12 is that it can be readily oriented during the coiling operation to present a desired surface of the wire feeing toward central passageway 24, a feature which is exploited in accordance with toe present invention. For example, the upper surface of the wire 12 from Figure 5 can be controlled to be the inner surface when toe wire 12 is coiled into the conduit 10. Thus, the lower surface of the wire 12 in Figure 5 can be controlled to be the outer surface of the conduit 10 when toe wire 12 is coiled. A round wire, without a major and minor axis, cannot be controlled in the same way, and therefore it can be difficult to ensure that treatment applied prior to coiling toe wire 12 ends up in toe desired location (inside or outside the coil, depending on toe treatment). [0051] There is a broad range of specifications for wire 12 and wire guide conduit

10. In a representative specification, wire 12 has a major axis A~A dimension ranging from approximately 0.050-0.110 inch, and a height along minor axis B-B ranging from approximately 0.033-.072 inch. Wire 12 can be formed into wire guide conduit 10 hairing a number of turns equaling approximately 9-20 windings per inch, depending on the wire cross-sectional dimensions.

[0052] Once coiled and formed into wire guide conduit 10, a representative configuration has an outer diameter of approximately 0.18 inches and an inner diameter for passageway 24 of approximately 0.08 indies, depending on the desired application and configuration of electrode wire 16. Of course, the thickness along axis

B-B of the wire 12 will affect the difference between the inner diameter of the conduit

10 and the outer diameter of the conduit 10 when the wire 12 is coiled such that axis

B-B is transverse to the longitudinal direction of the conduit 10. Various types of electrode wire 16 can be used with and fed through the wire guide conduit 10 of the present invention induding various steel, aluminum and other alloys having a wide range of cross-sectional diameters. Electrode wire 16 can also be of a cored or solid type. The electrode wire 16 has an outer diameter that is less than the inner diameter of the conduit 10. The size of the conduit 10 may be selected based on the electrode wire 16 to be used, or vice versa.

[0053] In accordance with the present disclosure, wire 12, after being formed to the desired cross-sectional shape and before being coiled to form wire guide conduit 10, is subjected to a local surface heating and hardening operation. The surface hardening operation creates localized regions of increased hardness, designated in the figures as regions 18. The regions 18 may be permanently defined on the wire 12 in a variety of shapes and/or patterns in a controlled manner, such that the regions 18 may be located specifically within the passageway of foe conduit 10 after winding, based on the controlled coiling afforded by the non-round cross-section of foe wire 12.

[0054] Referring to Figure 6, in one embodiment wire 12 is shown, not yet coiled, as having numerous stripes of hardened areas designated by reference number 18B.

Other patterns of forming regions 18 can be provided which are described in more detail in the following discussion. As shown in Figure 6, the stripe-shapes are arranged generally parallel to each other and are spaced apart approximately the same distance.

[0055] In a representative process, hardened areas 18 may be formed by subjecting wire 12 to laser radiation. A representative laser treatment system 26 is diagrammatical!y illustrated in Figure 7. As shown, laser source 28 directs of beam 30 of radiation energy toward wire 12 shown in this figure as being supported by fixture

32. Laser energy from source 28 causes local heating of the surface of wire 12. While numerous lasers may be suitable for this application, a fiber laser outputting radiation at 1,060 nanometers is suitable in some applications. Alternatively, a CCfe gas laser could be used having an output in the 10,600 nm range. Beam 30 forms a focal spot diameter of, for example 0.05 nm. Such local heating and foe subsequent quenching of the heated area causes surface hardening in a well-known manner. For example, in representative configurations, wire 12 formed of high carbon steel tempered to a hardness of 45-47 Rockwell C can be locally hardened in regions 18 to a level of about

58 Rockwell C. The surface hardening is desirably to a limited depth as shown in the cross-sectional view of Figure 5. In one representative configuration, the hardness depth is about 0.25 nm. By forming hardened regions 18 at local areas with a limited depth, their presence does not adversely impact the formabiiity of wire 12; allowing the wire to be coiled to form wire guide conduit 10. [0056] Various types of lasers and processes can be used to produce regions 18.

For example, wire 12 can be drawn through fixture 32 in a continuous manner with a pulsed laser directed to a surface of the wire producing a series of “dot” shaped regions

18A such as illustrated by Figure 8. In this approach, the feed rate of the wire 12 through the fixture may be held constant, with the pulse rate also held constant to create evenly spaced dots. In another aspect, the rate of the feed or the pulse rate may be varied to create variable spacing between regions 18.

[0057] Alternatively, laser beam 30 could be swept across the diameter of wire 12 and pulsed as the wire moves continuously (at a fixed rate) through fixture 32. Such sweeping can be done by moving toe axis of laser beam 30 relative to the wire crosssection or by physically moving wire 12 in a transverse direction with the laser beam axis being fixed. Put another way, the laser beam 30 moves laterally relative to the wire 12 as the wire is fed longitudinally. Such a process yields chevron shaped hardness patterns shown as regions 18B in Figure 6, In another process, laser beam

30 is pulsed and also stroked transversely relative to the diameter of wire 12, producing an alternating inclined orientation of regions 18C as illustrated in Figure 9.

[0058] Figure 10 illustrates another alternative pattern for toe heating effect produced by laser source 28. In this case laser beam 30 is tightly focused and cause to move in a circular pattern, for example having a circular diameter of about 3.0 nm.

As wire 12 moves a chained circular configuration of a regions 18D is produced. Since the hardness pattern results in curved regions 18D is separated by unheated portions, toe desired combination of locally hardened and softer annealed adjacent regions is provided. The chained circular patterns shown in Figure 10 appears similar to a coil, but these circles 18D are on toe surface of the wire 12, and the wire 12 is illustrated here prior to coiling. [0059] Figure 11 illustrates regions 18E produced by the same circular tracing of beam 30, but sweeping the beam across the diameter of wire 12 as it is moved continuously. Similar to Figure 10, the illustration of Figure 11 shows a pattern created on a surface of wire 12 that is shown flat and prior to coiling into the conduit.

[0060] These are only several example embodiments of a manner of creating locally hardened regions 18 on the surface of wire 12. As stated previously, the goal is to provide a sufficient number of hardened areas to create hardened “wear bar" regions without interfering with the ability to coil wire 12 to form wire guide 10.

[0061] Various spacing between hardened regions 18 can be provided. Referring in particular to Figure 3, a number of the hardened regions 18 are at designated locations. It is noted that these hardened regions 18, in the configuration shown, occur at various angular positions relative to central passageway 24. It is desired that these hardened regions 18 occur at various positions both longitudinally along central passageway 24 and at different radial positions to act essentially as “wear bars" such that the electrode wire 16 will make contact with these areas as it traverses through centra! passageway 24 regardless of how wire guide 10 is bent.

[0062] In one aspect, with the inner surface of the conduit 10 being divided into four quadrants, hardened regions 18 are disposed on each of the four quadrants along substantially the entire length of the conduit 10. Thus, the electrode wire 16 that passes through the conduit 10 may be in contact with multiple regions 18 on various radial portions of the electrode wire 16, thereby reducing overall friction as the electrode wire 16 passes through the conduit 10 relative to a conduit without hardened portions. [0063] In one aspect, the hardened regions 18 do not project substantially from the surface of the wire 12. Rather, as described above, the hardened regions 18 are located in a depth of tee thickness of the wire 12.

[0064] In one aspect, the hardened regions 18 are limited to the interior surface of the conduit 10. In this aspect, there are no hardened regions located on tee outer surface of the conduit 10.

[0065] In one aspect, tee hardened regions 18 do not extend fully across tee upper surface of the wire 12 when the wire is flat, and therefore do not extend into contact with adjacent coils of tee conduit 10 when tee wire 12 is coiled into tee conduit 10. As shown in Figure 3, tee rounded shaped of tee elliptical or oval cross-section creates recesses between adjacent coils of tee conduit 10. Thus, tee electrode wire 16 typically will not make contact with the base of thee recesses. Thus, hardening areas that are ultimately disposed within the recesses may not be necessary.

[0066] As tee electrode wire 16 passes through tee conduit 10, the electrode wire

16 makes contact bote with the hardened regions 18 as well non-hardened portions of the wire 12 that forms tee conduit 10.

[0067] A design trade-off occurs as the number and size of regions 18 increases so does tee likelihood of cracking or restrictions in flexibility of wire 12 as it is being coiled to form wire guide conduit 10. The optimum pattern in size for hardened regions

18 will be dependent upon numerous factors, including the materials and the sizes of wires 12 and 16, intended operational characteristics, drive systems used for advancing the electrode wire, etc.

[0068] The addition of the regions 18 to tee wire 12 therefore provides advantages of a harder wire with reduced friction relative to a softer wire, but with the formabiiity and ease of coiling made possible by tee use of the softer wire 12. [0069] Features of foe present invention may also find applications for other uses.

For example, illustrated in Figure 12 is conduit 34 having cable core 36 for use as a control wire as part of an actuation system. In this case, cable core 36 typically would move in a reciprocating manner. Despite this difference, features of resistance to movement and wear are present in this application as well. In this case, wire guide conduit 34 may be formed of a non-round wire and have the local hardened regions

18 as described previously. Control cable conduit 34 can be used with dutch cables, brake cables, throttle control cables, remote mirror control cables, door latch cables, and trunk and hood latch cables, etc.

[0070] In the foregoing description, various features of the present invention are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. ^" Thus, foe following claims are incorporated by reference herein in their entirety, with each claim standing on its own as a separate embodiment of foe present invention.

[0071] It is intended that the foregoing description be only illustrative of the present invention and that the present invention be limited only by the hereinafter appended claims.