Multi-wire feeder mechanism for hand-held welding laser heads

Abstract

A multi-wire feeder for delivering multiple wires along a wire path to a process area to be laser-treated is configured with a hub provided with two or more wire-routing passages. The passages are isolated from one another and open into the base of the hub where they converge towards a nozzle which is spaced downstream from the base. The nozzle is configured with an output channel extending between the converged wire-routing passages and an output port of the hub. The wire-routing passages are configured with respective upstream annular stretches receiving respective wires, and intermediate curved channels delivering respective wires to the output channel. The channel is shaped and dimensioned to position the delivered wires in a side-to-side position such that the wires exit in tandem from the output port of the hub and are uniformly deposited on the process area.

Description

MULTI-WIRE FEEDER MECHANISM FOR HAND-HELD WELDING LASER HEADSBACKGROUND OF THE INVENTION1. Field of the Invention

[0001] This invention relates to hand-held fiber laser welding systems. Particularly, the disclosure relates to a hand-held fiber laser head provided with a detachable multi-wire feeding mechanism configured to increase weld strength and weld dimensions.2. Background of the Invention

[0002] Welding is a basic process in a great variety of industries that requires the joining of similar or dissimilar materials. Known for a long time, traditional welding methods use an electric arc or flame, which generate concentrated heat, to join multiple workpieces. No longer a novelty, laser-welding gained popularity due to its precision, speed and ability to weld a wide range of materials. Unlike traditional welding, the laser welding uses a high- energy, tightly focused light beam incident onto the material’s surface to create a localized melt zone. This molten region is where the welding occurs, and upon cooling, it forms a strong bond.

[0003] In many cases, laser welding can be performed without filler wire, thanks to the precision and control it offers. However, there are numerous instances where filler wire is advantageous. Several factors may determine the need for filler wire in laser welding. One of the factors relates to the material type: different materials have respective different thermal properties requiring using filler wire to improve the joint. Still another factor includes gap bridging: laser welding is highly precise, but it may struggle to bridge larger gaps between materials. In such cases, welding wire is used to fill the gap and create a robust connection. Yet another factor is the joint strength: the use of welding wire is required to optimize the welding process. Depending on the application, additional material from welding wire can enhance the overall strength and durability of the weld. Still another factor relates to the process efficiency. Furthermore, while laser welding is fast, the use of filler wire can further enhance process efficiency and speed by ensuring consistent weld quality. While the above-mentioned and other factors each depend on a variety of physical parameters, the common denominator for all of them is the weld strength.

[0004] What is / are the criteria that may define the weld seam’s strength? Unfortunately, due to the relative immaturity of laser-welding, it has been difficult to apply internationally-recognized welding standards for safety certification. The application of these historical standards are based on external weld seam dimensions which determine the strength of the crystalline structure around a conventionally welded joint. Due to a small focal laser beam spot diameter, this beam produces a weld seam which is narrower than that produced by a conventional arc. Even a cursory inspection of laser- and electrical arc-produced weld seams unmistakably reveals the difference between these two: the arc- produced weld seam is the broadest. The physical appearance of the latter indicates that it contains more material to the weld joint by comparison to the laser welding even if the latter is accomplished using the wire. The more material, the stronger and broader the joint. Once the physical dimensions of the laser produced and conventional weld seams more closely match each other, the strength of the two joints can be compared, and thus the already-established welding standard can be applied. Meanwhile, in the absence of the established standards, the determination of the laser weld seam’s strength is rather subjective which causes the uncertainty among both the manufacturers and customers.

[0005] The above, of course, did not escape the attention of those skilled in the laser welding arts. The obvious solution to the discussed laser weld-related problems is the use of a single wire but with as large a dimeter as possible under the circumstances. However, while the strength of the laser weld seam may be improved, the demand for the laser energy required for inserting this large(r)-diameter wire is increased. This, in turn, decreases the efficiency of the laser welding process. Furthermore, even with a large-diameter wire, the laser weld seam still may be too narrow to allow the application of the standard diagnostic methods.

[0006] Another solution involves using multiple filler wires. This approach typically utilizes two wires fed through a single guide channel. A few examples of the dual filler wire feeder associated with a weld handgun can be found at https: / / www.you tube. com / watch?v::::KiGgiqC2'rxM and http s : Z / y outu. b e / s A VC 9iZ-z4o respectively. While technical details of the shown wire feeder in both videos are sketchy, based on the information and belief, the main hub of the shown feeder is configured witha single frustoconical through going channel extending between upstream and downstream ends of the hub. The wires are fed through this channel and exit the latter in a spaced-apart manner which renders the feeder cumbersome since it is necessary to ensure that the wires do not interfere with one another inside the feeder’s hub. To eliminate the space between the wires, the laser handgun or torch includes a special clamp provided on the output end of the torch which is configured to press the wires against one another. Not only the discussed configuration requires an additional component - clamp, but it also necessitates the user to bring free ends of the clamped wires together manually.

[0007] A need therefore exists for a compact multi-wire nozzle attachment / feeder for hand-held laser heads which overcomes the noted particularities of the known prior art wire feeder mechanisms.SUMMARY OF THE DISCLOSURE

[0008] The disclosed multi-wire feeder is configured to utilize feed wire from at least two or more separate lines which are delivered from a single wire source or respective wire sources during the process of laser welding. Generally speaking, the more material, the stronger the weld seam. This not so subtle generalization is well recognized in the laser welding field. Contrary to known dual wire feeders / nozzles, the wires in the disclosed feeder are output at a shallowenough angle to one another, such that respective opposing peripheries are in close, preferably continuous contact. However, due to reasonable manufacturing tolerances the expectation of the continuous contact may be impractical to intend, with mechanical interference possible with too tight of an output opening. Considering this, a minimal separation of the two wire lines not exceeding 1mm (for 1 / 16” wire) is allowed in the mechanical design. However, this may not affect the quality of the wire application, as the geometry of the torch’s nozzle tip provided with a closely positioned guiding groove, as well as the energy of the laser, ensure the wire is fed to the process area effectively regardless. The side-by-side position of the wires at the output of the disclosed attachment increases the external dimensions of a laser weld upon depositing the wires onto the process area. Based on the foregoing, the disclosed structure a) strengthens the weld and b) increases the external weld dimensions resembling those of a conventionally-welded joint, to which established international welding standards are applied.

[0009] Structurally, the desired side-to-side position of the wires at the output of the feeder is a result of the configuration of the latter. The latter includes a main routing hub, a hub cover, and a shaft collar-style adapter for mounting the entire attachment assembly to a hand-held welding torch or laser head.

[0010] The main hub is configured with a solid one-piece or multi-piece body in which two inlet ports are cross-drilled over a length defining thus respective wire-routing passages within the hub’s body. The passages gradually converge toward one another before merging into a short output channel opening into the output port of the hub. The output channel is common to both passages and shaped and dimensioned to position the wires in a side-by-side relationship such that their respective peripheries are spaced from one another at a distance varying from 0 to 1mm. As a result, the wires exit through the output port in tandem and are uniformly deposited on the process area.

[0011] The side-by-side position of the wires depends on a few factors or parameters selected to prevent creating a kink in the wires when joining. The geometry of the feeder along with the wire-routing passages are one of those parameters. As mentioned above, the passages converge at a shallow angle which is determined to be so gradual as to minimize the possibility of creating a kink in the wires upon joining. The passages each have multiple sections positioned along a wire delivery path and including an annular upstream linear annular section which extends downstream from an inlet port, curved intermediary section and downstream linear output section which is common for both wires. The intermediary and output section each are configured with a U-shaped cross-section and further referred to as a channel. The intermediary curved channel may be configured with an upstream convex sub-region and a downstream concave sub-region. The downstream concave sub-regions of respective channels converge downwards so as to define a shallow converging angle between the passages. The downstream output channel is common to both passage and receives two or more wires from respective lines. Due to the dimensions and shape of the output channel, the wires are positioned in a side-to-side arrangement with respective peripheries spaced from one another in a 0 - 1mm distance range.

[0012] The above and other features are discussed in detail below. Moreover, it is to be understood that both the foregoing information and the following detailed description are merely illustrative examples of various aspects and features which indicate that a particular feature, structure, or characteristic described may be included in at least with one other or all of the disclosed features.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Various aspects of the disclosure are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide an illustration and a further understanding of the various features, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of any particular embodiment. In the figures:

[0014] FIG. 1 is a perspective view of the disclosed multi-wire feeder attached to a hand-held laser head;

[0015] FIG. 2A is an exploded view of the assembly of FIG. 1;

[0016] FIG. 2B is illustrates different perspective view of the nozzle tip of the hand-held laser head of FIG. 1.

[0017] FIGs. 3 and 4 are respective perspective bottom and side views of the disclosed multiwire feeder;

[0018] FIG. 5 is a top sectional view of the disclose feeder of FIGs. 1 and 2 along the feeder’s longitudinal axis; and

[0019] FIG. 6 is a bottom view of the disclosed feeder of FIGs. 1 and 2.SPECIFIC DESCRIPTION

[0020] Referring to FIGs. 1-3, the illustrated welding assembly 10 includes the disclosed multiwire feeder 12 attached to a welding laser head which has a torch 14 and a nozzle assembly 16 coupled to laser head / torch 14 via intermediary parts which are not shown here. While feeder 12, as shown, features a dual-wire configuration, one of ordinary skill readily realizes that more than two wires can be used with the shown structure subject to the feeder’s dimensions and local environmental conditions. The disclosed configuration of feeder 12 is shaped and dimensioned to be compact and provides for a weld seam which has the strength considered to be a function of the number of filling wires and their positioning relative to one another. Furthermore, the weld seam produced with the help of multi -wire feeder 12 has the width comparable to that of electrical arc-produced weld seams. In particular, experimental feeder 12 produces the seam having the width varying in a 7 to 9 mm range provided two 1 / 16” filler wire are used for the laser welding operation, whereas standard arc welding utilizing the same wires typicallyproduces 8-10mm wide seams. As a result, thus produced laser weld can be tested and qualified based on well-established methods and standards for the arc-welded seams.

[0021] The feeder 12 is configured to provide a continuous welding operation of assembly 10. One of the requirements for such a continuous operation is to prevent the wires from interfering with each other in a manner that may stop or impede the advancement of one of or both wires. In other words, for the wires to be guided though output port 18 of feeder 12 in the side-to-side position, they should not be twisted or coiled or spiraled around each other upstream from output port 18 along a wire delivery path. To prevent unfortunate work stoppages of welding assembly 10, feeder 12 includes upstream wire-routing passages separated from one another until they merge together in a single downstream guide channel common to both passages. As a consequence, the interference of multiple wires within hub 22 is limited compared to the known prior art structures.

[0022] The feeder 12 is configured with a main hub 22 centered on an axis A- A’, a hub cover 24, and a shaft collar-style adapter 26 for mounting feeder 12 to torch and nozzle assembly 14. The input ports 32 (FIG. 3) are provided in a base 34 of hub 22 and receive respective adapters 30 (FIG. 2 A) which provide coupling between feeder 12 and two or more wire guides 28 extending between the feeder and a wire source or sources 25. The hub 22 further includes a nozzle 20 extending from base 34 and provided with output port 18. The base 34 and nozzle 20 can be two different parts coupled to one another, or may be made as a one-piece solid body generally having a frustoconical shape, although other shapes can be used as well.

[0023] Referring to FIGs. 5 and 6, input ports 32 and output port 18 define therebetween respective passages 38 and 40 extending along respective axes 54 and 56 and each including a circular upstream section 42, a U-shaped intermediate channel 44 and output channel 46. Generally, the input ports 32, upstream section 42 and intermediary channel 44 of each of passages 38, 40 are cross-drilled in hub 22 and converge in nozzle 20 at a 3±0.1° angle at a location M close to output port 18. The output channel 46 is common to both passages 38 and 40 and extends between the location M and output port 18.

[0024] As mentioned above, having upstream stretches 42 and intermediate channels 44 of respective passages 38 and 40 spaced apart within hub 22 at the very least minimizes the possibility of interference between the wires in hub 22 upstream from output channel 46 of the passages. To avoid the kinks while ensuring that the opposing sides of respective wires arejoined together in downstream channel 46, the converging angle, at which the passages merge into output channel 46, and the geometry of upstream stretch 42 and particularly intermediate channel 44 are of utmost importance. The converging angle between passages 38, 40 is a gradual 3±0.1°. As to the geometry of passages 38 and 40, upstream circular stretches 42 each are linear. The intermediary channels 44 each have a complex profile including upstream convex and downstream concave regions 48, 50 respectively, each with the radius of curvature of 200mm + / - 0.5mm. The radius for both curved regions may be uniform, or the regions 48, 50 (FIG. 6) may be configured with respective different radii. Instead of two regions, intermediate channel 44 may have a single radius of curvature.

[0025] The output channel 46 common to both passages 38, 40 is linear and dimensioned to provide the side-to-side position of the deposited wires which have respective opposing sides in continuous contact. The latter may be interrupted by small, practically imperceptible gaps due to various manufacturing imperfections or required tolerances. However, even if these gaps inadvertently exist, they are easily filled in by molten wires at elevated temperatures upon irradiating the process area by a laser beam, and held in position by geometric features inherent in the welding torch’s nozzle tip, as explained below.

[0026] Referring to FIG. 2B, nozzle tip 16 has a groove 15 provided in the outer bottom surface 17. The groove 15 is shaped and dimensioned to receive and maintain the side-by side-position of the wires in which the wires are located relative to one another in the distance range not exceeding 1mm. When feeder 12 is mounted to the laser head as shown in FIG. 1, groove 15 is substantially aligned with output port 18 ensuring that the wires are in the side-by-side relationship.

[0027] The width of stretch 46 is based on two considerations. On the one hand, stretch 46 should be narrow enough to prevent the separation between the wires, i.e., to provide a continuous contact between opposing sides of respective wires. On the other hand, this width should not be so small that the wires get stacked up which would lead to a relatively narrow weld seam and possibly to a wire delivery stoppage. Obviously, the width of downstream channel 46 should be at least twice as large as the diameter of individual wire which, for all practical purposes, is considered to be substantially the same as the width of individual intermediate curved channels 44. In the experimental samples, the width of downstream channel 46 is between 3.9 and 4.1mm, while its length varies between 4 and 5mm. This length is a result oftwo considerations. On the one hand, it should not be too short to ensure that the wire exit output port in the side-by-side parallel relationship. On the other hand, channel 46 should not be too long to prevent the wires from converging at a shallow-enough angle so as not to create too much friction between them. The disclosed feeder 12 is adapted for use with a variety of filling wires. Typically the wires guided through respective passages 38, 40 have a uniform shape and dimension, but the possibility of simultaneously using multiple wires with respective different shapes and dimensions is not excluded. For example, the largest and stiffest wire type delivered by feeder 12 is .063” or 1 ,6mm thick steel, while the smallest and most flexible wire type is .045” [1.1mm] thick aluminum. Based on the above, largest and smallest wire widths in combination with the pointed out length range, channel 46 is configured to provide smooth wire routing without mechanical interference.

[0028] The round passages 38 and 40 are drilled in the body of hub 22 and further, in order to join the two feed wire ends internally in output stretch 46, material is removed from nozzle 20 of hub 22 so as to open intermediate and output sections which explains why these sections are referred to as channels 44, 46. The curved intermediate sections 44 each are then ball-milled until joining together at output channel 46 which terminates in output port 18 of hub 22. In order to retain the feed wire within the U-shaped intermediate and output channel 44, 46, cover 24 of FIG. 1 is detachably coupled to and covers nozzle 20 of hub 22. The result of these manufacturing processes creates passages 38, 40 which both route and smoothly deposit respective feed wires on the process area.

[0029] The hub 22 is a compact structure and has certain elements dimensioned to help the smooth delivery of wires during a welding operation. For example, base 34 and output nozzle 52 (FIG. 5) are configured with respective widths Wb and We selected so that the ratio Wb / We ranges between 3 and 4. In exemplary feeder 12, base 34 is 32mm wide while distal end 52 is 9.3mm. The distance between axes 54 and 56 of passages 38 and 40, respectively, varies in a 10-15mm range, whereas the length of intermediate stretches 44 varies from 33 to 35mm.

[0030] The features disclosed herein in accordance with the present disclosure, are not limited in their application to the details of construction and the arrangement of components set forth in the above description or illustrated in the accompanying drawings.These features are capable of assuming other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting.

[0031] Having thus described several aspects of at least one example, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Accordingly, the foregoing description and drawings are by way of example only.

Claims

CLAIMS1. A multi-wire feeder for delivering multiple wires along a wire path to a process area to be laser-treated, comprising: a hub provided with two or more wire-routing passages isolated from one another and open into a base of the hub, the passages converging in a nozzle of the hub which is spaced downstream from the base; an output channel provided in the nozzle and extending between the converged wirerouting passages and an output port of the hub, wherein the wire-routing passages are configured with respective: upstream annular stretches receiving respective wires, and intermediate curved channels delivering respective wires to the output channel which is configured to position the delivered wires in a side-to-side position such that the wires exit in tandem from the output port of the hub and are uniformly deposited on the process area.

2. The multi-wire feeder of claim 1, wherein the intermediate curved channels of respective wire-routing passages each include an upstream convex region and a downstream concave region, the upstream convex and downstream concave regions having respective radii of curvature each varying in a 200±0.5mm range.

3. The multi-wire feeder of claim 2, wherein the radii of curvature are equal to one another or different from one another.

4. The multi-wire feeder of claim 1, wherein the output channel is dimensioned so that the wires in the side-to-side position have respective opposing peripheral regions in contact with one another.

5. The multi -wire feeder of claim 1, wherein the wire-routing passages converge towards one another at an angle varying in a 3±0.1° range.

6. The multi-wire feeder of claim 1, wherein the output channel is U-shaped and dimensioned to have a width which is at least twice a width of each of the intermediated channels.

7. The multi -wire feeder of claim 1, wherein the upstream stretches of respective wirerouting passages each have a proximal end defining an input port, which has a diameter greater than that of a distal end of the upstream stretch.

8. The multi-wire feeder of claim 1, wherein the hub is configured with a frustoconically- shaped body, the base and nozzle of the hub having respective widths with the width of the base being 3-4 times larger than that of the nozzle.

9. The multi-wire feeder of claim 1, wherein the body of the hub is configured as a one- piece body or multiple pieces coupled to one another.

10. The multi-wire feeder of claim 1 further comprising a cover detachably coupled to and covering the nozzle of the hub.

11. A welding assembly comprising: a hub provided with two or more wire-routing passages isolated from one another and open into a base of the hub, the passages converging in a nozzle of the hub, which is located downstream from the base, and merging into an output channel which extends between the converged wire-routing passages and an output port of the hub, the output channel being configured to position the delivered wires in a side-to-side position such that the wires exit in tandem from the output port of the hub; a hand-held laser head configured with a torch and a nozzle tip which is detachably mounted to the torch, the nozzle tip having a bottom which has an outer surface provided with a pair of grooves; and an adapter configured to detachably mount the hub to the nozzle tip which is spaced downstream from the output port so that the grooves receive respective wires exiting the output port and ensure the side-to-side position of the wires during a welding operation.

12. The welding assembly of claim 11, wherein the passages further being configured with respective: upstream annular stretches receiving respective wires, and intermediate curved channels delivering respective wires to the output channel and each include an upstream convex region and a downstream concave region, the upstream convex and downstream concave regions having respective radii of curvature each varying in a 115±0.5mm range.

13. The welding assembly of claim 12, wherein the radii of curvature are equal to one another or different from one another.

14. The welding assembly of claim 11, wherein the output channel has a length varying between 4 and 5mm and a width varying between 3.9 and 4.1mm.

15. The welding assembly of claim 11, wherein the intermediate curved channels converge towards one another at an angle varying in a 3±0.1° range.

16. The welding assembly of claim 11, wherein the output channel is U-shaped and dimensioned to have a width which is at least twice a width of each of the intermediated channels.

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