Arc welding torch with non-melting electrode, with one torch body and combined extraction and protective gas nozzle

Description

[0001] The invention relates to an arc welding torch with a non-consumable electrode and with a torch body having a combined extraction and shielding gas nozzle according to the preamble of claim 1.

[0002] Thermal arc welding processes use energy to melt and join the workpieces. In sheet metal fabrication, MIG, MAG, TIG, and plasma welding are standardly used.

[0003] Arc welding devices generate an electric arc between the workpiece and a consumable or non-consumable welding electrode to melt the weld metal. The weld metal and the weld area are shielded from atmospheric gases, primarily nitrogen (N2), oxygen (O2), and hydrogen (H2), by a shielding gas stream.

[0004] In this process, the welding electrode is mounted on the torch body of a welding torch, which is connected to an arc welding machine. The torch body typically contains a group of internal, current-carrying components that direct the welding current from a power source in the arc welding machine to the tip of the torch head and onto the welding electrode, from where the arc is then generated and transferred to the workpiece.

[0005] The shielding gas flows around the welding electrode, the arc, the weld pool, and the heat-affected zone on the workpiece, being supplied to these areas via the torch body. A gas nozzle directs the shielding gas flow to the front of the torch head, where it exits the torch head in an approximately ring-shaped pattern around the welding electrode.

[0006] In the prior art, the gas flow to the gas nozzle is usually achieved via components made of a material with low electrical conductivity (polymers or oxide ceramics), which can also serve as insulation.

[0007] The electric arc generated during welding heats the workpiece and any added filler material during the welding process, causing them to melt. The arc energy input, high-energy thermal radiation, and convection result in a significant heat input into the torch head. Some of this heat is dissipated by the shielding gas flowing through the torch head, passive cooling in the ambient air, and heat conduction into the torch hose assembly.

[0008] Above a certain welding current load on the torch head, the heat input becomes so high that active cooling of the torch head is necessary to protect the components from thermal material failure. For this purpose, the torch head is actively cooled with a coolant that flows through it, thereby dissipating the unwanted heat absorbed from the welding process. Deionized water with added ethanol or propanol for antifreeze can be used as a coolant, for example.

[0009] Besides welding, brazing is also a viable option for joining sheet metal components. Unlike welding, brazing melts only the filler material, not the workpiece itself. This is because brazing joins two edges using the solder as the filler material. The melting points of the solder and the component materials are significantly different, so only the solder melts during the process. In addition to TIG, plasma, and MIG torches, lasers are also suitable for brazing.

[0010] For arc brazing, argon I1 or argon mixtures with admixtures of CO2, O2, or H2 according to DIN ISO 14175 can typically be used. For TIG brazing, commercially available TIG torches can be used.

[0011] In this type of device, cooling of the non-consumable electrode and thus of the burner can be achieved by keeping the surfaces of the burner components exposed to the protective gas flow as large as possible.

[0012] To capture the fumes and pollutants produced during welding as close as possible to the source, i.e., the welding process, torches with integrated extraction systems are provided.

[0013] From EP 2 298 485 A1, a burner with an extraction housing is known which encloses the burner neck in a relatively short section. An extraction hose is connected to the extraction housing, which is routed parallel to the remaining section of the burner neck and to the handle with the burner hose assembly.

[0014] EP 0 835 711 A2 relates to a welding torch with an extraction pipe that surrounds the torch neck and forms a flue gas channel in the space between the neck and the torch. The extraction pipe transitions into an extraction nozzle at the front. The flue gas is extracted directly at the welding point. The extraction pipe is firmly connected to the torch neck by means of a triple brace and a union nut. At the handle end, the extraction pipe terminates in an extraction hose that runs externally alongside the torch handle, similar to a bypass.

[0015] From EP 3 300 827 A1, a TIG welding torch with a flue gas extraction device is known. An extraction housing is attached directly to the torch head. The flue gas drawn in via the extraction housing is routed parallel to the torch neck through a flexible hose in the manner of a bypass and fed downstream via the handle and a hose assembly connected to it to an extraction fan.

[0016] From JP 2021-023 972 A, a torch device for arc welding is known, comprising a torch housing in which an electrode rod is arranged, and a nozzle arranged on the torch housing, which has a first unit that surrounds the electrode rod. Furthermore, the nozzle has a shielding gas outlet opening and a welding fume extraction opening.

[0017] EP 2 842 684 B1 relates to a welding torch system for use in welding or cutting operations that produce fumes, wherein the welding torch system comprises a welding torch with a contact tip holder having a contact tip formed by a consumable electrode.

[0018] US patent 3 886 344 A describes a gas-metal arc welding gun in which a fume extraction system is designed to completely surround the nozzle.

[0019] Marconi M et al "Capture efficiency of integral fume extraction torches for GMA welding - Part 2" - Welding in the World, Springer, DE, Vol. 54, No. 3 / 4, March 1, 2010 (2010-03-01), pages 15-33, reveals a variety of different extraction device designs for torch nozzles.

[0020] US 2006 / 226136 A1 relates to a hand-held torch for welding or cutting with a nozzle intended to remove smoke and fumes, wherein a fume extraction duct is arranged within the torch handle.

[0021] A disadvantage of such a device is that the handling of the burner is restricted by the extraction system located on the burner head. In particular, a previously known method of attaching the extraction nozzle to the burner head is disadvantageous, as it necessitates a modification of the burner head's design. Interchangeability of the burner body with or without extraction is not possible. Furthermore, the extraction volume flow is severely limited by the routing of the flue gas through the duct running parallel to the burner neck.

[0022] Based on the disadvantages described above, the invention aims to provide an improved gas nozzle and an improved burner body, which have a compact design and ensure safe and easy operation.

[0023] This task is solved with an arc welding torch with a combined extraction and shielding gas nozzle according to claim 1.

[0024] The invention relates to a combined extraction and shielding gas nozzle of an arc welding torch with a non-consumable electrode, such as a TIG or plasma torch, with a shielding gas channel for supplying shielding gas to the welding process and an extraction device integrally connected with the shielding gas channel for extracting the fume gas occurring during the welding process.

[0025] As mentioned, a disadvantage of the current technology is that the flue gas, extracted via a nozzle on the burner head, is routed through a hose, acting as a bypass, into the handle and from there discharged via the hose assembly. This severely restricts the burner's handling.

[0026] In contrast, the invention proposes attaching the suction device to the handpiece. While in the prior art the nozzle is fixed to the burner head, in the invention the flue gas is routed via the burner head and a guide on the burner body into the handle, rather than via a separate bypass line. In the invention, the flue gas is guided from the nozzle on the burner head, through the burner body of the nozzle, to the handle.

[0027] Furthermore, the welding torch with the nozzle according to the invention can only be used when the nozzle with extraction system is mounted, because the shielding gas channel is integrally connected to the extraction system. This safety feature provides optimal protection for the user against fumes.

[0028] Furthermore, due to its single-piece design, less installation space is required and fewer components are needed in the overall structure, which allows for a simpler design of the individual components.

[0029] Furthermore, the nozzle is lighter and smaller in size compared to the state of the art due to the monolithic design of the protective gas channel and extraction device.

[0030] According to a first advantageous embodiment of the invention, the extraction device has at least one extraction channel for the flue gas that surrounds the shielding gas channel at least partially coaxially. In this way, the flue gas generated during the welding process is guided coaxially to the shielding gas in the shielding gas channel in at least one extraction channel. The flue gas therefore flows in the nozzle in the opposite direction to the shielding gas. This design results in a particularly compact nozzle construction. Preferably, the shielding gas channel and the extraction channel can be arranged concentrically to each other.

[0031] According to the invention, the extraction device has several extraction openings for the flue gas arranged circumferentially around the burner body, preferably evenly distributed over the burner body. The extraction openings can be arranged at approximately the same distance from one another, with each extraction opening being in fluid communication with the extraction device via the extraction channel. In this way, the flue gas is extracted evenly. Preferably, an even number of extraction openings can be provided to allow for the molding of the nozzle.

[0032] According to the invention, the nozzle is electrically insulating and consists essentially of a ceramic material, preferably aluminum oxide. The ceramic is both temperature-resistant and electrically insulating. Despite this, assembly and disassembly are simple and not as complex as with nozzles known from the prior art.

[0033] A particular advantage is that the extraction openings of the extraction device are arranged axially offset from the nozzle's shielding gas outlet with respect to the nozzle's longitudinal axis. The flue gas is thus routed via the inlet nozzle, but unlike the prior art, this design requires no modification to the burner head. Routing the flue gas coaxially with the actual burner body to the housing is easy to implement. No bypass is required, and, most importantly, no modification of the burner body itself is necessary.

[0034] In a further development of the invention, the protective gas channel and the at least one extraction opening are arranged radially and axially offset. This outward and less forward-facing orientation is particularly important for the extraction of ozone as a gaseous pollutant, which is induced by the arc radiation and only forms at some distance from the process. Here, the invention provides a greater degree of freedom by arranging the extraction section, i.e., the extraction openings, further back and directed outwards. In contrast, in the prior art embodiment, the burner head itself must be modified, since the intake nozzle is attached to the burner head in the area where the ceramic nozzle of the burner is mounted.

[0035] Another advantage of this design is that the extraction of the flue gas and the supply of the protective gas occur sequentially in the direction of flow; that is, protective gas flows out at the front end of the nozzle, and extraction only takes place behind it (viewed in the direction of flue gas extraction). This largely prevents the protective gas from being heated by hot flue gases.

[0036] According to an advantageous embodiment of the invention, the extraction device has a dome- or cupola-shaped area at its end facing the protective gas outlet opening. Such a design allows the size of the area of ​​the component surface covered by the protective gas to be influenced.

[0037] The extraction openings can be provided, at least partially, in the dome- or cupola-shaped area of ​​the extraction device.

[0038] A particular advantage is that the flow cross-section of the shielding gas channel widens towards the burner-side end of the nozzle. This improves access to the constrictions in the nozzles.

[0039] According to an advantageous embodiment of the invention, the extraction channel connects to the shielding gas channel in the area where the shielding gas channel widens towards the burner-side end of the nozzle.

[0040] The goal is a homogeneous, turbulence-free shielding gas flow. The design of the shielding gas channel depends on accessibility and, in some cases, the view of the arc, the tungsten electrode, or the weld metal. The standard nozzle shape is round. An oval shape is also conceivable, for example, in narrow-gap applications, where the secondary axis ensures accessibility and the main axis enlarges the flow chamber sufficiently to prevent excessive flow velocity and turbulence. Generally, a round shape is advantageous in almost all applications because it is orientation-independent.

[0041] According to an advantageous embodiment of the invention, the extraction openings are provided to have an elliptical or oval cross-section, in particular that the main axis of the elliptical or oval cross-section extends approximately parallel to the longitudinal axis of the nozzle.

[0042] In a further advantageous embodiment of the invention, the nozzle has a thread, in particular a threaded insert, for screwing onto a burner body. This ensures easy mounting and replacement of the nozzle on the burner, especially on the burner body.

[0043] The nozzles can be manufactured in different lengths. For example, short or long versions can be used under different application conditions. These versions differ in the quality of the shielding gas coverage due to the different laminar flow paths. Furthermore, the different nozzle lengths also necessitate different tungsten electrode lengths, which in turn affects the current-carrying capacity due to ohmic heating in the electrode. Thus, the nozzle length has a limited influence on the welding process.

[0044] According to an advantageous embodiment of the invention, an extraction pipe for extracting the flue gas is in fluid connection with the extraction device of the nozzle.

[0045] It is conceivable that the extraction pipe is part of a handle for the burner, in particular that the handle is formed from two half-shells.

[0046] Further objectives, advantages, features and application possibilities of the present invention will become apparent from the following description of an exemplary embodiment with reference to the drawing.

[0047] Some of these show schematically: Figure 1 is a perspective view of a combined extraction and protective gas nozzle, Figure 2 is a sectional view of the nozzle according to Figure 1 with an internal thread for screwing onto a burner body, Figure 3 shows another sectional view of the nozzle according to Figure 1 Figure 4 shows a burner body with nozzle according to Figure 1and Figure 5 a sectional view of the burner body according to Figure 4 .

[0048] Identical or equivalent components are identified in the following figures of the drawing by reference numerals based on an embodiment, in order to improve readability.

[0049] Out of Figure 1 A combined extraction and shielding gas nozzle 10 for an arc welding torch with a non-consumable electrode, in particular TIG or plasma torch, is shown.

[0050] This nozzle 10 is attached to a Figure 1 The burner head of the burner body 12 (not shown) is arranged, in particular screwed on. Such a burner body 12 is available in the Figures 4 and 5 depicted.

[0051] The nozzle 10 has a shielding gas channel 1 for supplying shielding gas to the welding process, which in the present embodiment is guided centrally in the nozzle 10.

[0052] The shielding gas channel 1 is in this case integrally connected to an extraction device 3 connected to the shielding gas channel 1 for extracting the fume gas occurring during the welding process.

[0053] In the embodiment described here, the extraction device 3 has an extraction channel 6 for the flue gas that surrounds the shielding gas channel 1 at least partially coaxially. For extracting the flue gas, several extraction openings 7 are provided around the circumference of the burner body, in this case evenly distributed over the burner body. These extraction openings 7 are in fluid communication with the at least one extraction channel 6. Preferably, the shielding gas channel 1 and the extraction channel 6 can be arranged concentrically to each other.

[0054] The extraction openings 7 can have an elliptical or oval cross-section and the main axis 11 of the elliptical or oval cross-section can extend approximately parallel to the longitudinal axis 5 of the nozzle 10.

[0055] The extraction openings 7 of the extraction device 3 are arranged axially offset from the shielding gas outlet opening 2 of the nozzle 10 with respect to the nozzle longitudinal axis 5. Furthermore, the shielding gas channel 1 and the at least one extraction opening 7 are arranged radially and axially offset. In other words, the extraction openings 7 are set back relative to the gas outlet 2 for the shielding gas in the direction of flue gas flow and radially outwards, so that these extraction openings 7 are spaced away from the welding process.

[0056] The fumes or pollutants generated during the welding process are drawn through the extraction openings 7 into at least one extraction duct 6 and extracted through an extraction pipe or duct 13 located in a handle of the torch. The extraction of the fumes and the supply of the shielding gas occur sequentially in the direction of flow; that is, shielding gas flows out at the front end of the nozzle 10, and extraction takes place downstream of it (viewed in the direction of fume extraction). This largely prevents the shielding gas from being heated by hot fumes.

[0057] As from the Figures 1 to 3 As can be further seen, the extraction device 3 has a dome- or cupola-shaped area 4 at its end 8 facing the protective gas outlet opening 2, wherein the extraction openings 7 are provided at least partially in the dome- or cupola-shaped area 4 of the extraction device 3.

[0058] As in particular the sectional view according to Figure 2 As the gas can be extracted, the flow cross-section of the shielding gas channel 1 widens towards the burner-side end of the nozzle 10. The extraction channel 6 connects to the shielding gas channel 1 in the area where the shielding gas channel 1 widens towards the burner-side end of the nozzle 10.

[0059] According to the invention, the nozzle 10 is designed to be electrically insulating. For this purpose, it is made of a ceramic material, preferably aluminum oxide. As can be seen from the Figures 4 and 5 As can be seen, the nozzle 10 is arranged on the torch body 12 for the thermal joining of at least one workpiece, in particular for arc welding. Figure 2 It is evident that the nozzle 10 in the present embodiment has a thread 9 for screwing onto the burner body 12. It is also conceivable that the nozzle 10 has a threaded insert for screwing onto the burner body 12.

[0060] Furthermore, the Figures 4 and5 to remove a suction pipe 13 for the extraction of the flue gas, which is in fluid contact with the extraction device 3 of the nozzle 10.

[0061] The extraction pipe 13 is part of a handle 14 for the burner, which in this case is formed from two half-shells 15. Reference symbol list

[0062] 1 Shielding gas channel 2 Shielding gas outlet opening 3 Extraction device 4 Dome-shaped or cupola-shaped area 5 Longitudinal axis of nozzle 6 Extraction channel 7 Extraction openings 8 End of extraction device 9 Thread 10 Shielding gas extraction nozzle 11 Main axis of the elliptical cross-section 12 Burner body 13 Extraction pipe 14 Handle 15 Half-shells

Claims

1. Arc welding torch with non-consumable electrode, in particular TIG or plasma torch, comprising a torch body (12) for thermally joining at least one workpiece having a combined extraction / shielding gas nozzle (10) with a shielding gas duct (1) for feeding shielding gas to the welding process, characterized in that the extraction / shielding gas nozzle (10) contains an extraction device (3), which is connected in one piece to the shielding gas duct (1), for extracting the fumes that occur during the welding process, wherein the extraction device (3) has a plurality of circumferentially arranged extraction openings (7), which are distributed uniformly over the nozzle (10), for the fumes, wherein the extraction / shielding gas nozzle (10) is designed to be electrically insulating and consists substantially of a ceramic material.

2. Arc welding torch according to Claim 1, characterized in that the extraction device (3) has at least one extraction duct (6) for the fumes which at least regionally coaxially surrounds the shielding gas duct (1).

3. Arc welding torch according to Claim 1, characterized in that the extraction openings (7) of the extraction device (3) are arranged axially offset relative to the shielding gas outlet (2) of the nozzle (10) with respect to the nozzle longitudinal axis (5).

4. Arc welding torch according to Claim 1 or 2, characterized in that the shielding gas duct (1) and the at least one extraction opening (7) are arranged radially and axially offset.

5. Arc welding torch according to any of the preceding claims, characterized in that the extraction device (3) has, at its end (8) facing towards the shielding gas outlet opening (2), a dome-shaped or domed region (4).

6. Arc welding torch according to Claim 5, characterized in that the extraction openings (7) are provided at least regionally in the dome-shaped or domed region (4) of the extraction device (3).

7. Arc welding torch according to any of the preceding claims, characterized in that the flow cross section of the shielding gas duct (1) widens towards the torch-side end of the nozzle (10).

8. Arc welding torch according to any of the preceding claims, characterized in that the extraction duct (6) adjoins the shielding gas duct (1) in the region in which the shielding gas duct (1) widens towards the torch-side end of the nozzle (10).

9. Arc welding torch according to any of the preceding claims, characterized in that the extraction openings (7) have an elliptical or oval-shaped cross section.

10. Arc welding torch according to Claim 9, characterized in that the main axis (11) of the elliptical or oval-shaped cross section extends approximately parallel to the longitudinal axis (5) of the nozzle (10).

11. Arc welding torch according to any of the preceding claims, characterized in that the nozzle (10) has a thread (9) for screwing onto the torch body (12).

12. Arc welding torch according to Claim 1, characterized in that the extraction pipe (13) is part of a handle (14) for the torch and the handle (14) is formed from two half-shells (15).