One of the lingering problems in the field of welding is the consistent formation and placement of a quality weld bead. Various measures have been employed to achieve this goal. For instance, the waveform of the welding current has been closely controlled to achieve better weld bead formation and weld bead quality. In addition, the feed rate of a weld wire has been controlled to produce a higher quality weld bead. The composition of the consumable weld wire and various types of shielding gases used during the welding process have also been employed to achieve higher quality weld beads. Although many of these techniques have significantly improved weld bead quality, consistent weld bead placement on a workpiece has remained illusive.
A remaining problem with obtaining a consistent weld bead placement on a workpiece, however, is the position of the weld wire relative to the workpiece as the weld bead is being formed. It has been found that when the position of the tip of the weld wire varies relative to the welding tip of a welder, the consistency of the weld bead placement degrades. It is common industry practice to feed a “killed” weld wire to a welder during the welding process. A “killed” weld wire is a weld wire that has had its shape memory removed prior to the weld wire being wound onto a reel, spool, container, or the like. However, when the weld wire is wound onto the reel, spool, container, or the like, the weld wire adopts a new shape as it is being wound. Thereafter, when the weld wire is unwound from the reel, spool, container, or the like, the weld wire adopts a new shape during the unwinding process. As a result, the shape of the unwound wire will vary along the longitudinal length of the unwound weld wire. If the unwound weld wire is cut into one or more sections, the unwound wire retains its adopted shape obtained when being unwound from the reel, spool, container, or the like. Further modifications to the shape of the weld wire can result during the cutting process and/or while the weld wire is positioned for being cut and/or as the weld wire is fed into the welding machine. Since the weld wire essentially has no memory, the weld wire constantly modifies its shape as it passes through the weld gun, thus resulting in inconsistent positioning of the weld wire as it exits the welding tip of the welding gun or torch. This inconsistent positioning of the weld wire results in inconsistent placement of the weld bead onto a workplace.
Various techniques have been used by operators to minimize this attribute of the weld wire. One technique is for the operator to cut the weld wire in certain positions relative to the unwound weld wire to obtain a desired weld wire profile for the cut weld wire section. The operator can further modify the shape of the weld wire by hand as he/she deems fit. Although these techniques can improve weld bead placement on a workpiece, the weld bead placement consistency varies widely between operator and from the use of different cut sections of the weld wire.
During manual welding, the operator has the ability to attempt to correct and/or compensate for weld bead placement. However, such techniques are inapplicable to robotic welders. When the weld wire is automatically fed into a welding machine, such as in a robotic welder, problems with consistent weld bead placement can be severe. Typically, robotic welders follow a predefined path when forming a weld bead. The varying position of the weld wire as it exits the welding tip of the robotic welder can cause significant weld bead placement deviation during the welding process.
Attempts have also been made to improve welds by providing a weld wire having a shape memory in the form of a sinusoidal waveform with a relatively small cast having a curve radius in the range of about 60-100 inches and a mean average radius of about 80 inches. Some examples are taught in U.S. Pat. No. 6,820,454 and 6,708,864 assigned to the assignee of the instant patent application and the teachings of which are incorporated by reference by their entirety. Although, weld wire formed with a small cast has been proven to be superior over other prior art weld wires, there is always a need in industry for further improvements.
In view of the historic problems of weld bead placement during a welding operation, there is a persistent demand for an improved weld wire which addresses the problems associated with consistent weld bead placement onto a workpiece.
The present invention pertains to an improved weld wire, an article of manufacture including the improved weld wire on a spool, and a process for making the improved weld wire for use with various types of welding machines. These welding machines can include automated welders and manual welders. In addition, the weld wire can be used in various types of welding processes such as MIG, MAG, or STT welding, or in other types of welding processes wherein a consumable electrode is utilized to form a weld bead onto a workpiece. The improved weld wire and spool for holding the weld wire in accordance with the present invention involves the utilization of a weld wire with a shape memory having a large cast imparted onto the weld wire prior to and/or at the time the weld wire is wound onto a reel, spool, container, or the like, and which shape memory is fully or substantially retained by the weld wire as the weld wire is unwound from the reel, spool, container, or the like.
The use of weld wire with a shape memory having a large cast is a deviation from prior common industry practices that teach that weld wire that is fed into a welding machine should have either little or no shape memory or, if shape memory is provided, that the cast imparted into the wire should be small and that a reverse twist process should be used to cause controlled weld wire rotation during its payout. Heretofore, the common practice in the industry was to “kill” the wire to remove the shape memory of the wire prior to winding the weld wire onto a reel, spool, container, or the like or to effect a reverse twist in weld wire having a small cast after it is payed off from a holding spool. It was commonly believed that a weld Wire having a shape memory would adversely affect the unwinding of the weld wire from the reel, spool, container, or the like during the welding process and would further be more susceptible to kinks, bends and other problems as the weld wire is fed through the welder during the welding process. Furthermore, it was commonly believed that a weld wire with shape memory would aggravate the problem associated with consistent weld bead placement. Surprisingly, the use of a shape memory weld wire having a large cast in accordance with the present invention results in the formation of a weld bead having better consistent placement during the welding operation and the formation of higher quality weld beads than weld beads formed by “killed” weld wires. The use of a weld wire with such shape memory defining a large cast has also been found to form a more robust weld bead during the welding process. Furthermore, the use of a weld wire with such shape memory has been found to reduce the occurrence of bends and kinks in the welding wire as it is being used during the welding process such as during the feeding of the weld wire through a welding machine during the welding process.
In accordance with the present invention, there is provided a weld wire with a predefined shape memory having a large cast imparted onto the welding wire prior to the welding wire being wound onto a reel, spool, container, or the like. The shape memory of the weld wire is fully or partially retained by the weld wire as the weld wire is wound onto a reel, spool, container, or the like and as the weld wire is fed through a welding machine. The shape memory on the weld wire can be formed from a variety of processes such as, but not limited to, a casting process. The shape memory imparted onto the weld wire can occur during the formation of the weld wire and/or by a process subsequent to the formation of the weld wire. In a preferred embodiment, the weld wire is formed by a casting process wherein the weld wire is imparted a shape memory during the casting process. As can be appreciated, the weld wire can be formed by other processes substantially equivalent to a casting process. In another aspect of this embodiment, the desired shape memory imparted onto the weld wire is formed subsequently to the formation of the weld wire by an extrusion process or by any other process now know or hereinafter conceived or developed. In this aspect, the shape memory imparted onto the weld wire during the formation of the weld wire can be partially or fully removed from the weld wire and subsequently the desired shape memory is then imparted on the weld wire by one or more processes, such as, but not limited to, a casting process.
In another aspect of the present invention, the desired shape memory imparted onto the weld wire is selected to maximize the consistency of weld bead placement on a workpiece. In one embodiment, the shape memory of the weld wire is imparted substantially in one plane along the longitudinal length of the weld wire.
In its preferred application during a welding operation, the weld wire is unwound from the spool while the spool is maintained in a non-rotatable position. During the unwinding process, the weld wire is typically under tension and does not revert back to its imparted shape until or unless the weld wire is cut into a section. At that time, the cut wire section reverts back into a uniform waveform. It is to be appreciated that cutting the weld wire is not a part of a typical welding operation using the subject weld wire, however.
In yet another aspect of this embodiment, the weld wire, when cut and laid upon a flat ground surface, rises above the flat ground surface less than about 6 inches, generally less than about 5 inches, typically less than about 4 inches, more typically less than about 3 inches, even more typically less than about 2 inches, and still even more typically less than about 1.5 inches. As can be appreciated, the less the weld wire deviates from the single plane, the better the consistency of weld bead placement typically obtained.
In another embodiment, the shape memory imparted on the weld wire is in multiple planes. In this embodiment, the predefined shape of the shape memory on the weld wire has a repeating pattern which exists in multiple planes and which results in a more consistent weld bead placement during the welding process. In one aspect of this embodiment, the deviation from the predefined shape memory in multiple planes is less than about 6 inches, generally less than about 5 inches, typically less than about 3 inches, more typically less than about 2 inches, and even more typically less than 1.5 inches. As can be appreciated, better weld bead placement is typically obtained as the deviation from the desired shape memory that has been imparted onto the weld bead approaches zero.
In still another embodiment, the desired shape memory imparted onto the weld wire is a waveform; however, as can be appreciated, other shapes for the shape memory can be imparted onto the weld wire. In one aspect of this embodiment, the maximum amplitude of the waveform is substantially the same throughout the length of the cut section of the weld wire. The maximum amplitude of each half cycle of the weld wire as observed when cut can vary slightly depending upon the position of the weld wire on the reel, spool, container, or the like as it is being unwound from the reel, spool, container, or the like. Furthermore, the maximum amplitude of the half cycle of the cut weld wire can also vary depending on the weld wire diameter. Generally, the deviation of the maximum amplitude of each half cycle within one cycle of the cut weld wire varies less than about 6 inches, typically less than about 4 inches, more typically less than about 2 inches, and even more typically less than about 1 inch. As can be appreciated, the less deviation from maximum amplitude to maximum amplitude for each half cycle of the cut weld wire results in better consistency of weld bead placement typically obtained. In another aspect of this embodiment, the maximum amplitude of each half cycle of the cut weld wire is generally more than about 100 inches, typically 100-300 inches, more typically about 150-250 inches, and even more typically about 175-225 inches. The mean average radius is about 100 inches but not less than about 80 inches. As can be appreciated, other maximum amplitudes can be used for various types of welding operations. In still another aspect of this embodiment, the length of each cycle of the cut weld wire section is the same or substantially the same for adjacent positioned cycles. The length of each cycle of cut weld wire section can vary depending on the position of the weld wire as it is being unwound from a reel, spool, container, or the like. The diameter of the wire can also affect the length of each cycle of the cut weld wire section. Generally, the deviation of the length of each weld wire section is less than about 15 inches, typically less than about 10 inches, more typically less than about 6 inches, and even more typically less than about 5 inches, and still even more typically less than about 2 inches. As can be appreciated, the less deviation from the length of the cycle to the cycle of the cut weld wire, the better the consistency of the weld bead's position will be typically obtained. The length of each cycle of the cut weld wire sections will vary depending on the particular weld operation. Generally, the length of each cycle of the cut weld wire section is more than about 200 inches, and typically more than about 300 inches, and more typically about 600 inches. As can be appreciated, other wire dimensions can be used. In still yet another embodiment of the present invention, the imparted shape memory on the weld wire creates a waveform for a cut section of the weld wire, wherein each half cycle has a substantially semi-circular shape, wherein each half cycle for each cycle of the cut weld wire section has substantially the same radius.
In still yet another aspect of the present invention, the shape memory imparted onto the weld wire is selected to improve the quality of the weld bead and facilitate in the formation of the weld bead. In one embodiment, the shape memory imparted onto the weld wire causes the weld wire to flip as the weld wire is fed through the welding tip of the welding gun. This flipping phenomenon results in the welding wire always being in the same or substantially in the same position relative to the welding tip as the welding wire is fed through the welding tip, thereby resulting in a more consistent position of the weld bead. The number of flips of the weld wire is typically dependent on the number of loops. In another embodiment, the shape memory imparted onto the weld wire inhibits or reduces the susceptibility of the weld wire being bent or otherwise kink as it is being unwound from a reel, spool, container, or the like and/or as the weld wire is fed through the weld gun or torch or other components of the welding machine. When the weld wire bends, kinks or otherwise does not properly feed through the welding machine during the welding process, the consistency of position of the weld bead and/or the quality of the weld bead can deteriorate. The use of the shape memory weld wire reduces such incidences since the imparted shape memory resists changes in such imparted shape, thereby improving the consistency of high quality weld beads and better ensuring consistent placement of the weld bead during the welding process. In still another embodiment, the shape memory imparted onto the weld wire facilitates physical and electrical contact between the weld wire and the welding tip of the welding gun. The imparted shape memory onto the welding wire causes the welding wire, as it travels through the welding tip of the welder, to maintain engagement with the side of the welding tip prior to exiting the welding tip. This continuous contact prevents heat producing electrical arching between the tip and the weld wire during the welding process, thereby achieving a higher quality and more robust weld bead during the welding process.
In still yet another aspect of the invention, an article of manufacture includes a weld wire having a desired shape memory imparted thereto and a spool including a substantially cylindrical hub portion having a diameter adapted to carry the weld wire so that the desired imparted shape memory is substantially retained in the weld wire after the weld wire is unwound from the spool. For weld wires having a generally fixed radius of curvature in the range of about 100-300 inches, the diameter of the cylindrical hub portion is in the range of about 18-20 inches. Preferably, for weld wire having a solid core and a diameter of about 0.035 inches, the diameter of the hub portion of the spool is about 18 inches. For weld wire having a solid core and a diameter of about 0.062 inches, the diameter of the hub portion of the spool is about 20 inches. The article of manufacture as set out above is a replaceable component in an arc welding system.
It is the primary object of the present invention to provide an improved weld wire which obtains better placement consistency of the weld bead onto a workpiece.
It is another and/or alternative object of the present invention to provide a weld wire which has an imparted shape memory defining a large cast. The cast preferably lies in a substantially single plane.
It is still another and/or alternative object of the present invention to provide a weld wire which has reduced susceptibility to bending and/or kinks as the weld wire is unwound from a reel, spool, container, or the like and/or as the weld wire is fed through a welding machine.
It is yet another and/or alternative object of the present invention to provide a weld wire which facilitates in the heating of the weld wire during the welding process.
It is still yet another and/or alternative object of the present invention to provide a weld wire which forms a more robust weld.
It is a further and/or alternative object of the present invention to provide a weld wire which reduces inconsistency of shape when being cut into sections by an operator.
It is yet a further and/or alternative -object of the present invention to provide a weld wire which can be successfully used in robotic welding to obtain consistent placement of the weld bead onto a predefined path on a workpiece.
It is still yet a further and/or alternative object of the present invention to provide a weld wire having a shape memory in the form of a waveform. In one aspect, the shape memory is in the form of a sinusoidal waveform having a mean average radius of curvature of about 200 inches but not less than about 80 inches. In another aspect, the shape memory is in the form of a sinusoidal waveform has a generally fixed radius of curvature in the range of about 100-300 inches but not less than 100 inches.
It is another and/or alternative object of the present invention to provide a weld wire which has a desired shape memory imparted on the weld wire after the weld wire has been formed and prior to the time the weld wire is wound onto a reel, spool, container, or the like.
It is yet a further and/or alternative object of the present invention to provide a method of manufacturing or otherwise forming a weld wire having the above identified characteristics and others.
It is a still further and/or alternative object of the present invention to provide a spool for holding the improved weld wire and an article of manufacture including the improved weld wire carried on the spool. In one aspect, the spool includes a substantially cylindrical hub portion having a diameter adapted to carry the weld wire so that the desired imparted shape memory is substantially retained in the weld wire after it is unwound from the spool.
In another aspect, the spool has a hub portion with a diameter in the range of about 18-20 inches for carrying weld wire having a diameter in the range of about 0.035-0.062 inches.
These and other objects of the invention will become apparent to those skilled in the art upon reading and understanding the following detailed description of the preferred embodiments taken together with the drawings.
Referring now to the drawings wherein the showings are for the purposes of illustrating the preferred embodiments only and not for the purpose of limiting same,
With continued reference to
It is to be appreciated that common industry practice has heretofore taught that weld wire unwound from a spool should be “killed.” In other words, the memory of the weld wire should be removed prior to the weld wire being wound onto a spool of weld wire. As such, when weld wire is unwound from a spool such as generally illustrated in
In accordance with one prior method, a desires shape memory is imparted onto the weld wire at the time the weld wire is formed and/or at a time subsequent to the weld wire being formed. The shape memory is in the form of a waveform having a relatively small cast, typically having a generally fixed radius of curvature in the range of about 15-40 inches. In one prior method, a substantially linear cast is imparted into the weld wire in the form of an undulating curve including a succession of small generally semi-circular sections defining half cycles of the waveform. The length of each cycle is typically less than about 150 inches, and more typically 40-120 inches, and even more typically 50-100 inches, and still even more typically 60-90 inches.
With reference next to
As illustrated in the figure, the spool 30 carries weld wire 60 on the hub portion 32 between the first and second flange members 34, 36. In most typical arc welding system applications, the first and second flange members have an overall outer dimension a of 40 inches. In addition, the hub portion 32 of typical prior art spools has an outer diameter dimension b of between about 10-12 inches. Still further, those skilled in the art appreciate that spools 30 holding weld wire 60 are sold in commerce as articles of manufacture 40 for easy replacement into arc welding systems 10 as additional weld wire is needed. In practice, empty spools are simply replaced with packed spool articles 40 as necessary. Typically, spools are traded in commerce carrying 100 pounds of weld wire 60. As can be appreciated, therefore, the spool width c defined between the spaced apart first and second flange members 34, 36 are defined in order to accommodate a build-up layered outer diameter d of weld wire without wasted space and without extending the build-up beyond the outer diameter a which would prevent the spool from being received into the weld storage portion of the associated arc welding system.
In addition to being mechanically impractical, the occasional loss of contact between the tip and weld wire temporarily interrupts the electrical circuit therebetween. Typically, this causes arching which generates large amounts of heat in the tip which adversely affects the quality of the weld and makes control over the welding process difficult. The preferred embodiment according to the instant application closely approximates the wire 60″ of
Referring now to
Surprising, it has been found that the use of a weld wire having shape memory with a large cast with a mean average radius of not less than 80 inches results in the placement of a weld bead during the welding operation which is more consistent and of a higher quality than weld beads formed by a “killed” weld wire having little or no shape memory or formed by weld wire having a wall cast. The use of the shape memory weld wire with a large cast also has been found to create a more robust weld bead during the welding process.
The desired shape memory imparted onto the weld is preferably imparted onto the weld wire at the time the weld wire is formed. However, it may be imparted at a time subsequent to the weld wire being formed. The weld wire is typically informed by standard wire casting processes; however, other processes can be used such as extrusion and others now know or here. During the casting process, the weld wire has a shape memory imparted onto the weld wire. Initially, the weld wire is first “killed,” using suitable rollers as illustrated in
Referring still to
The waveform of the shape memory weld wire causes the weld wire to flip as the weld wire is fed through the welding tip of the welding gun. This flipping phenomenon results in the weld wire being in substantially the same position relative to the welding tip after each flip rotation as the weld wire is fed through the welding tip, thereby resulting in a more consistent positioning of the weld bead during the welding process. The number of flips of the weld wire is dependent on the number of loops of the weld wire on the spool.
As shown in
Referring now to
With reference next to
The invention has been described with reference to the preferred embodiments. These and other modifications of the preferred embodiments as well as other embodiments of the invention will be obvious from the disclosure herein, whereby the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims.