torch head for an arc welding machine and arc welding machine

Abstract

Torch head (10) for an arc welding machine (70) with a contact tube (16) which is designed to provide a welding electrode (76) during a welding process, a sleeve (14) which radially surrounds the contact tube (16) on the outside, and an arc control device which has at least one electromagnet (18) and is designed to magnetically influence a generated arc during the welding process, wherein the electromagnet (18) is arranged radially between the contact tube (16) and the sleeve (14) in a welding-side end region of the torch head (10), wherein the arc control device has a pivoting device which is designed to pivot the electromagnet (18) for an alignment of the poles of the electromagnet relative to the contact tube (16).

Description

Technical field

[0001] The present invention relates to a burner head for an arc welding machine and to an arc welding machine in which an arc can be magnetically influenced. State of the art

[0002] Welding is a common process for permanently joining two components, for repairs, and for adding material. For example, vehicle bodies are welded in many areas. Turbine blades, for instance, can also be repaired by welding.

[0003] A commonly used welding process is arc welding. In this process, an electric arc is generated at a welding electrode of a welding machine by an electrical energy source. The arc can extend to a workpiece, which then acts as the counter electrode. Alternatively, the welding machine can also have a second welding electrode to which the arc then extends. This arc melts material from the component and, optionally, also the welding electrode. The molten material can fuse and then solidify, for example, to form a weld seam.

[0004] Arc control is crucial for the quality of a weld. When welding at very high power, the arc can become destabilized and rotate eccentrically relative to the longitudinal axis of the welding electrode. Such eccentric rotation can also be intensified or caused by vibrations and impacts during welding. A weld seam shaped in this way can be uneven, and the welding process can be considered unstable. This can be counteracted by reducing the welding power, but this makes the welding process less efficient.

[0005] It is known that magnetic fields can be used to improve arc welding. However, providing a suitable device with magnets to generate such a magnetic field is complex. Magnets can be quickly damaged by spatter during welding if they are placed very close to the arc. Conversely, if the distance is too great, the influence on the arc may be insufficient and / or require excessive energy to influence it. Furthermore, permanently installed magnets are very difficult to adapt to different welding situations and processes. Extensive programming is often necessary, which can be overwhelming for an operator, especially during manual welding. When welding with multiple electrodes simultaneously, targeted influence using magnets is often hardly feasible with a reasonable amount of effort.For example, if two arcs with a phase shift are used for welding and magnets are attached to the outside to influence the arcs, the arcs are not identical and cannot be individually controlled. Similarly, an arc between two welding electrodes of a welding machine can only be influenced unsatisfactorily by magnets attached to the outside of the two welding electrodes.

[0006] WO 2018 / 057487 A1 describes a method, a device and a system for influencing a magnetic field for welding processes.

[0007] The JP H08-300 150 A describes a friction welding machine.

[0008] CN 1 02 825 364 A describes a magnetically controlled arc sensor device used in seam tracking.

[0009] CN 1 13 042 860 A describes a device for generating a high-frequency longitudinal magnetic field for magnetically controlled welding. Description of the invention

[0010] A first aspect of the invention relates to a torch head for an arc welding machine. The torch head can form the part of the welding machine at which the arc is generated. The torch head can, for example, hold a welding electrode. During a welding process, the torch head is held near the part to be welded. An arc welding machine can be a welding machine in which the heat required for welding is generated at least partially by the arc. The arc can at least partially melt the welding electrode and / or the component to be welded. An arc is generated, for example, by impact ionization of the air at a sufficiently high electrical voltage and / or current density. The arc welding machine can, for example, be operated with direct current or alternating current. The arc itself can be a plasma. The plasma can be electrically conductive.The arc can be formed, for example, between a workpiece and a welding electrode of the arc welding machine during welding. However, the arc can also be formed between two different welding electrodes, which function, for example, as the anode and cathode. Such an arc between two welding electrodes is also referred to as a non-transferred arc. The non-transferred arc may, for example, not make contact with the component being welded. The torch head can be designed, for example, for an MSC welding machine or a TIG welding machine. The torch head can be detachably or permanently connected to the rest of the arc welding machine. The torch head can be a consumable part that often needs to be replaced due to spatter and / or melting damage.The arc welding machine can be designed for manual welding and / or for use in a welding robot. Heat can also be applied to the arc welding machine using methods other than the arc. For example, the welding electrode, the weld pool, and / or the workpiece can be additionally heated with a laser.

[0011] The torch head features a contact tube. The contact tube is designed to supply a welding electrode during a welding process. Alternatively or additionally, the torch head may have a receiving area, such as an inner sleeve, through which the contact tube is guided and / or by means of which the torch head is held against the contact tube. For example, the contact tube can fix the welding electrode if it is not melted during the welding process. The contact tube can guide the welding electrode to the welding area, for example, if the welding electrode is melted during the welding process. The welding electrode may, for example, be designed as welding wire, which is continuously fed through the contact tube manually or by a conveying device during the welding process. The welding electrode may be made of, for example, CrNi steel or tungsten.

[0012] The contact tube can be designed to electrically connect the welding electrode to the power source of the arc welding machine. For example, the contact tube can be connected to the power source via an electrical conductor, such as a flexible power cable. The welding electrode can, for instance, rest against the contact tube, and the current can thus be transferred from the contact tube to the welding electrode. For example, the inner diameter of the contact tube can correspond to the outer diameter of the welding electrode, allowing a surface of the welding electrode to make full contact with a surface of the contact tube, thereby forming an electrical connection. Current can then flow from the contact tube to the welding electrode and generate the arc at its free end. The contact tube can, for example, have a round or square cross-section. The contact tube can, for example, extend parallel to the welding electrode.The contact tube can, for example, extend axially through the burner head. The contact tube can have a central through-opening. The contact tube can be made of a highly electrically conductive material, such as copper.

[0013] The torch head has a sleeve. The sleeve surrounds the contact tube radially on the outside. There may be a radial gap between the sleeve and the contact tube. The sleeve may be radially spaced from the contact tube. The sleeve and the contact tube may be electrically insulated from each other. The sleeve and the contact tube may be connected to each other. The sleeve may be attached to a base body of the torch head, for example, with electrical insulation, and spaced from the contact tube. The contact tube may also be attached to the base body, for example, with electrical insulation. The base body may, for example, be connected to a handle of the arc welding machine. The sleeve can prevent accidental contact between a user or a component and the contact tube. Furthermore, the sleeve can protect the contact tube from damage and spatter.The sleeve can form a nozzle for a shielding gas, for example, if the arc welding machine is designed as a gas-shielded arc welding machine. The sleeve can be a simple cylindrical sleeve or a part that tapers towards the welding area in a nozzle-like shape. The sleeve can be made of a metallic or ceramic material, for example. A metallic sleeve can be very robust. A ceramic sleeve can be very heat-resistant and also electrically insulating.

[0014] The torch head incorporates an arc control device. This device is designed to magnetically influence the generated arc during the welding process. The arc control device includes an electromagnet. This influence can be active, achieved by generating a magnetic field, for example, by energizing the electromagnet. The electromagnet is, for instance, powered by direct current during operation. In a very simple embodiment, the electromagnet can be connected to the same power source as the welding electrode. However, the influence can also be passive, for example, by the arc inducing a current flow in the electromagnet during the welding process. The arc can be influenced continuously or intermittently.The arc can be controlled, for example, by a control device on the arc welding machine. The current and thus the generated magnetic field can be changed during the welding process. The arc control device, and in particular its respective electromagnets, can be connected to the arc welding machine's electrical power supply. An electromagnet can, for example, have a coil which generates a magnetic field as a result of an electric current flowing through it. A core, for example made of a ferromagnetic material such as iron, can be arranged inside the coil. The coil itself can, for example, be made of copper wire.

[0015] The magnetic influence on the welding arc can affect its spatial position and / or shape. For example, a magnetic influence can focus the arc, similar to optical focusing. This can reduce the size of the weld pool and / or increase the penetration depth. The arc can also be widened by magnetic influence, allowing, for example, material to be deposited over a larger area in additive welding. Alternatively or additionally, the arc control device can also be designed to influence material molten during the welding process, particularly that of the welding electrode. For example, the path of the molten material from the welding electrode to the workpiece can be influenced. This path typically follows the arc, making it possible to influence the arc while the material is molten.Magnetic influence on the welding arc can also stabilize it. For example, magnetic fields can suppress eccentric rotation of the arc, thus enabling stable welding with particularly high power. The arc control device can also induce or enhance a targeted rotation of the arc, for example, concentrically around a longitudinal axis of the welding electrode. This can have a positive effect on the welding process.

[0016] The electromagnet is arranged radially between the contact tube and the sleeve. This design protects the electromagnet. Furthermore, it eliminates the need for electrical insulation of electromagnet components, such as the coil, as the sleeve prevents contact with the welding machine operator. Additionally, this proximity allows the electromagnet to be positioned very close to the arc, resulting in a very strong influence on the arc. In contrast, electromagnets located outside the torch head or sleeve must generate a significantly stronger magnetic field to achieve the same effect. The sleeve also shields the magnetic field within its boundaries. Therefore, the torch head with the arc-influencing device is also suitable for arc welding machines with multiple torch heads, such as in welding without arc transfer to the workpiece.

[0017] The electromagnet is located in a welding-side end region of the torch head. This welding-side end region can be an axial section facing the welding arc. This arrangement allows the influence of the electromagnet's magnetic field on the arc to be particularly strong. The electromagnet can thus be positioned very close to a free end of the welding electrode and also to the torch head as a whole. For example, the electromagnet can be located at the level of one end of the contact tube from which the welding electrode protrudes. The welding electrode might, for instance, protrude approximately 10 mm from the contact tube. Due to the electromagnet's proximity to the arc, it can be very compact while still generating a sufficiently strong magnetic field to influence the arc during the welding process. This allows the electromagnet to fit between the contact tube and the sleeve even in small torch heads.

[0018] The arc control device can have multiple electromagnets. The respective design specifications for a single electromagnet apply equally to other electromagnets, where applicable. For example, all electromagnets of the arc control device can be arranged radially between the contact tube and the sleeve in a welding-side end region of the torch head. Alternatively, the electromagnets can be arranged in a radial plane of the torch head. Or, for example, the electromagnets can be arranged symmetrically within the torch head. Finally, the electromagnets can be arranged at uniform circumferential intervals around the contact tube. If the electromagnets are movable, a corresponding adjustment device can be used to move them together. The electromagnets can also be fixed in place.The arc control device can have an even number of electromagnets. This can, for example, simplify or even make possible symmetrical arc control. For instance, the arc control device can have two or four electromagnets. However, it can also have three, five, six, seven, eight, or more electromagnets. Experiments have shown that four electromagnets allow for a very compact and cost-effective burner head. Furthermore, many different arc control methods are possible with four electromagnets.

[0019] In one embodiment of the torch head, it is designed to supply shielding gas between the contact tip and the sleeve during the welding process. The welding machine can be configured accordingly for gas metal arc welding (GMAW). The torch head can form a gas channel between the contact tip and the sleeve, for example, by means of a radial gap between the sleeve and the contact tip. This space or gas channel between the sleeve and the contact tip can, for example, be essentially annular. The gas channel can be connected to a shielding gas supply device of the welding machine, for example, via a flexible or rigid gas line. The shielding gas can, for example, consist of argon, oxygen, and CO2 in predetermined proportions. The shielding gas can also be an inert gas. The shielding gas can, for example, prevent undesirable influences of the ambient air on the weld pool.

[0020] The electromagnet can be positioned in the gas channel between the contact tube and the sleeve. The shielding gas can flow around and cool the electromagnet. This allows the electromagnet to be operated at high power. Furthermore, this prevents damage caused by overheating from the adjacent welding arc. The torch head can thus be used at high welding power and high temperatures, despite the arc control device. The torch head can also be designed to allow the shielding gas to cool the electromagnet of the arc control device.

[0021] Alternatively or additionally, the torch head can be designed for alternative cooling of the electromagnet of the arc control device. For example, the coil of the electromagnet can be hollow internally, allowing water or air to flow through it for cooling. The welding machine can, for instance, have a water pump connected to the coil of the electromagnet via a water line.

[0022] In one embodiment of the torch head, the arc control device is designed to passively reduce arc instability. Arc instability can manifest as a tendency for the arc to undergo uncontrolled and / or undesirable spontaneous changes in shape and / or direction during the welding process, such as eccentric rotation. The torch head with the arc control device can be designed for self-regulation of the generated arc. The arc, with its magnetic field, can induce a current flow into the respective electromagnets of the arc control device, particularly if the arc changes during the welding process, for example, in its shape and / or direction.The electromagnet generates a magnetic field due to the induced current flow, which can counteract changes in the shape and / or orientation of the arc relative to the torch head. This dampens or even completely prevents eccentric rotation or fluctuations of the arc. No control of the arc control device or electrical power supply may be necessary. The passive reduction of arc instability can be achieved by changing the position of the individual electromagnets, for example, relative to the contact tube. For instance, the electromagnets can be moved closer to the arc and / or their poles aligned perpendicular to the arc to enhance the passive reduction of arc instability.Passive reduction of arc instability can be particularly effective with an even number of electromagnets, such as four symmetrically arranged electromagnets. "Passive" in this context means that no regulation, control, and / or power supply are necessary for the reduction. However, passive reduction of arc instability can also be combined with active control of the arc, for example, by supplying power to the individual electromagnets.

[0023] The arc control device may, for example, include electromagnets designed to actively control the arc. These electromagnets may be connected to a power source and / or have adjustable magnetic fields. The arc control device may also include additional electromagnets designed only to passively reduce arc instability. These electromagnets may not be connected to a power source and / or have fixed magnetic fields. However, passive reduction of arc instability may be achieved by changing the position of these electromagnets. Alternatively, these electromagnets may be fixed in their position.For example, the arc control device can have four energizable electromagnets in a first radial plane for actively controlling the arc, and four non-energizable electromagnets in a second radial plane for passively reducing arc instability. The second radial plane can be arranged axially to the welding side of the first radial plane, or vice versa.

[0024] In one embodiment of the torch head, the arc control device includes an adjustment mechanism by means of which the position of the electromagnet can be set, for example, relative to the contact tube, sleeve, and / or welding electrode. This allows, for example, the passive instability reduction effect to be modified. Furthermore, the magnetic field can be aligned relative to the arc. This allows the type of control to be altered. For example, in the case of multiple electromagnets, the positions of the electromagnets can be coupled together. The adjustment mechanism can be designed to rotate and / or move the electromagnet, several electromagnets together, or all electromagnets together. The adjustment mechanism can be designed for adjustment during the welding process.This allows the user to adjust the arc control even during the welding process. This enables intuitive control and adaptive application. For example, an experienced welder can adjust the weld pool and penetration depth based on their own judgment and experience, without needing a scientific understanding of the underlying effects or complex calculations of the required parameters. Alternatively, the arc welding machine can also have a control device and / or a sensor device for controlling the adjustment mechanism, the current flow to the electromagnets, and / or the arc itself. For example, a camera can detect the arc, and the position and current flow of the respective electromagnets can be automatically adjusted, for instance, to achieve a desired arc state. The path of the detected arc can also be taken into account.The shape, orientation, and / or strength of the electric arc can be recorded, for example.

[0025] The disclosure also relates to a torch head for an arc welding machine with a contact tube designed for providing a welding electrode during a welding process, a sleeve radially surrounding the contact tube, and an arc control device comprising at least one electromagnet and designed to magnetically influence a generated arc during the welding process, wherein the arc control device includes an adjustment mechanism. In this embodiment, the respective electromagnets can, for example, also be arranged outside the sleeve.

[0026] According to the invention, the arc-influencing device includes a pivoting device configured to pivot the electromagnet for aligning its poles relative to the contact tube. For example, the pivoting device can be part of the adjustment device described above. The electromagnet can be pivoted by the pivoting device in a plane extending radially to the contact tube. For example, a radially outer end of the electromagnet can be rotatably mounted by the pivoting device. An opposite end of the electromagnet can be pivoted radially inward. For example, a straight line between the two poles of the electromagnet can extend tangentially in one position and radially in another.For example, the electromagnet can be pivotable by at least 45°, 75°, 90°, or 120° and / or by a maximum of 120°, 140°, 160°, 180°, or 190°. One pole of the electromagnet can, for example, be an axial end and / or a south or north pole depending on the current applied. Depending on the orientation of the respective electromagnets and their current applied, the arc can, for example, be focused, spread out, stabilized, destabilized, set into rotation, and / or deformed asymmetrically.

[0027] The swivel mechanism can be designed for manual swiveling of the electromagnet from outside the sleeve. For example, the sleeve can have a slot-shaped opening through which an operating element of the swivel mechanism, such as a lever or a gear, protrudes. This operating element can be connected to a rotating plate on which individual electromagnets are mounted for swiveling. The individual electromagnets can be mounted directly on the plate or via an intermediate element, such as a rod. Manual swiveling allows the user to intuitively adjust the arc according to the current welding situation, even during the welding process. This also eliminates the need for electronics. Alternatively, an actuator can be provided in the torch head by means of which the electromagnet, or multiple electromagnets, can be swiveled.The actuator can, for example, include an electric motor. The actuator can, for example, be arranged radially between the contact tube and the sleeve. The actuator can, for example, be arranged axially on a side of the electromagnet facing away from the weld end. This can provide heat protection.

[0028] In addition to the rotating plate, the swiveling device or burner head can also have a stationary plate, which is, for example, fixed to the contact tube. This stationary plate can have additional guide tracks by which the respective electromagnets are mounted and guided during swiveling. For example, this stationary plate can have a slot-like guide track for each electromagnet, in which a rod or other element is guided. This rod or other element can be connected to a swiveling end of the electromagnet and thus provide additional guidance. The rods or other elements that hold the electromagnet can also form part of a power supply line for a coil of the electromagnet. The electromagnet(s) can also be mounted only on one side, for example by means of a rod, and swiveled there, for example by rotating the rod.Then the rotating plate can be omitted. The fixed plate can, for example, be arranged axially spaced on a side of the rotating plate facing away from the welding end.

[0029] In one embodiment of the torch head, the arc control device includes a displacement device designed to axially displace the electromagnet relative to a welding-side end of the torch head. For example, the displacement device can move the electromagnet toward or away from the welding-side end of the torch head. The axial displacement can be translational. For example, the displacement device can be part of the adjustment device described above. The electromagnet can be displaced by the displacement device along an axis extending parallel to the contact tube. For example, the electromagnet can be mounted on a sliding plate, which can also be used to pivot the electromagnet.The plate can also be arranged axially or in a completely fixed position within the burner head, while the electromagnets can be moved relative to the plate. For example, the electromagnet can be moved a few millimeters towards or away from the arc. This allows for easy adjustment of the field strength acting on the arc without having to adjust the current to the electromagnet. The degree of passive reduction of arc instability can also be adjusted in this way without requiring, for example, any modification of the electromagnet. Due to the three-dimensional field lines, the type or direction of the influence can also be adjusted by axial displacement. The adjustment range for axial displacement can be limited in both directions by a stop.

[0030] The repositioning device can be designed for manual repositioning of the electromagnet from outside the sleeve. For example, the sleeve can have a through-opening through which a control element of the repositioning device, such as a wheel or gear, protrudes. This control element can be coupled to an axially displaceable plate on which the respective electromagnets are mounted, for example, via a gear. The control element can be rotatably mounted on the sleeve. Manual repositioning allows the user to intuitively adjust the arc according to the current welding situation, even during the welding process. Furthermore, this eliminates the need for electronics to adjust the power supply to the electromagnets while still allowing adjustment of the effective field strength acting on the arc.Alternatively, an actuator can be provided in the torch head, allowing the electromagnet or multiple electromagnets to be repositioned. The actuator can, for example, include an electric motor. The actuator can be arranged radially between the contact tube and the sleeve. Alternatively, the actuator can be arranged axially on the side of the electromagnet facing away from the welding end. This allows the electromagnet and other components to protect the actuator from heat during welding.

[0031] The actuator can be configured for automatic and / or manual control. A first actuator can be provided for axial displacement and a second actuator for pivoting. Depending on the design, the electromagnets can be pivoted and displaced both manually and automatically. The individual poles of the electromagnets can also be manually or automatically adjustable, for example, by reversing their polarity.

[0032] In one embodiment of the torch head, the torch head is provided with a heat shield arranged on the welding side relative to the electromagnet. The heat shield can also be arranged on the welding side relative to the entire arc control device. The heat shield can be positioned radially between the contact tube and the sleeve in a welding-side end region of the torch head. The heat shield can be designed to protect the electromagnet or, more generally, the arc control device from heat and / or spatter during the welding process. The heat shield can be plate-shaped. The heat shield can be mounted, in particular attached, to the sleeve, the electromagnet, and / or the contact tube. For example, the heat shield can be pressed in, glued, screwed in, or otherwise fastened. The heat shield can be electrically insulating.The heat shield can be designed, for example, as a ceramic plate. It can have one or more openings for the shielding gas. For instance, larger holes can be provided as gas channels, or the heat shield can be sieve-like. The heat shield can be thicker radially on the inside than in a radially adjacent area. This allows for particularly good heat protection near the arc. The radially inner area can be free of openings for the shielding gas. The radially inner area can, for example, be essentially flush with the contact tube. The radially inner area can have an opening through which the welding electrode can be guided and in which, optionally, part of the contact tube can be arranged. The radially inner area can also be spaced axially from the contact tube, allowing the shielding gas to flow directly around the welding electrode.A radially central area of ​​the heat shield can have ribs over which the respective electromagnets are pivoted, thus providing strong heat protection for an inwardly pivoted position of the electromagnet, despite openings for protective gas in this radially central area. A radially outer edge area of ​​the heat shield can be free of openings for protective gas, thus providing strong heat protection for an outwardly pivoted position of the electromagnet. The heat shield can have a central opening through which the contact tube is guided.

[0033] In one embodiment of the torch head, the electromagnet comprises a coil, a core, and electrical insulation between them. The electrical insulation allows the electromagnet to be very compact. This insulation can be provided by a coating on the core, such as a ceramic layer. The coil can be free of any insulating coating, making the electromagnet highly heat-resistant. In contrast, conventional electrical insulation with a plastic sheath around the coil wire could easily be damaged by heat during welding, for example.

[0034] In one embodiment of the burner head, the electromagnet is curved. This allows the electromagnet to be particularly strong, as its field strength can correspond to a specific axial length. For example, the electromagnet can be curved between its two poles. The core of the electromagnet can also be curved in the radial plane. This curvature can correspond to a curvature of the inner circumference of the sleeve facing the contact tube. This maximizes the length of the coil and the core in the space between the sleeve and the contact tube, especially when multiple electromagnets are used. Alternatively, the electromagnet can be straight. In this case, the electromagnets can be very cost-effective.

[0035] A second aspect concerns an arc welding machine. The arc welding machine has one or more torch heads as described in the first aspect. The respective advantages and further features can be found in the description of the first aspect, whereby embodiments of the first aspect also form embodiments of the second aspect and vice versa.

[0036] The arc welding machine has an electrical power supply. This power supply can be designed to generate an arc for welding at the welding electrode or between multiple welding electrodes. The power supply can, for example, provide direct current and / or alternating current. The power supply can, for example, regulate the current flow to the welding electrode. The power supply can include a battery and / or a generator. The power supply can be designed to connect the arc welding machine to a mains power supply. The power supply can, for example, include a rectifier. The arc welding machine can include the welding electrode, which is held, for example, in the contact tube.The arc welding machine may include a feed device for the welding electrode. The arc welding machine may have a handpiece to which the torch head is either detachably or permanently attached. The electrical power supply may include a control device to adjust the current supply to the welding electrode and / or the arc control device.

[0037] In one embodiment of the arc welding machine, the machine is designed to supply power to the electromagnet of the arc influencing device. For example, the arc influencing device can be powered by the same electrical power supply that provides the electrical energy for generating the arc. The strength and / or type of electric current for the electromagnet can differ from the strength and / or type of electric current used to generate the arc. The power supply to the electromagnet can be adjustable. For example, the current flow and / or voltage for the electromagnet can be adjustable. This allows the generated magnetic field to be adjusted. The polarity, and therefore the pole, of the electromagnet can be reversible.With multiple electromagnets, the energy supply can be adjusted separately for each electromagnet, individually or collectively.

[0038] The arc welding machine may have a control device for adjusting the electromagnet, for example by pivoting and / or axially displacing it. The arc welding machine may have a sensor device for detecting the arc. For example, the arc may be detected optically. Alternatively or additionally, the magnetic and / or electric field of the arc may be detected. The orientation of the electromagnet and / or its power supply may be automatically adjusted depending on the detected arc. Alternatively or additionally, the orientation of the electromagnet and / or its power supply may also be linked to at least one welding parameter. For example, the magnetic influence on the arc may be automatically adjusted to the welding power and / or the arc's power supply.However, the magnetic influence on the arc can also be adjusted purely manually. Brief description of the characters Fig. Figure 1 illustrates in a schematic perspective view a torch head of an arc welding machine, which has an arc control device with four electromagnets. Fig. Figure 2 illustrates a burner head in a schematic perspective view according to Fig. 1 without a sleeve. Fig. Figure 3 illustrates a schematic top view showing a first position of the four electromagnets. Fig. Figure 4 illustrates a second position of the four electromagnets in a schematic top view. Fig. Figure 5 illustrates a third position of the four electromagnets in a schematic top view. Fig. Figure 6 illustrates the first position of the four electromagnets in a schematic perspective view of the burner head without the sleeve. Fig. Figure 7 illustrates the second position of the four electromagnets in a schematic perspective view of the burner head without the sleeve. Fig. Figures 8-14 each illustrate different operating modes of the arc control device in a schematic top view. Fig. Figure 15 schematically illustrates an arc welding machine in which the torch head is arranged according to Fig. 1 can be used. Fig. Figure 16 illustrates another embodiment of the burner head in a schematic perspective view. Fig. Figure 17 illustrates another embodiment of the burner head in a schematic perspective view. Fig. Figure 18 illustrates another embodiment of the burner head in a schematic perspective view. Fig. Figure 19 illustrates another embodiment of the burner head in a schematic perspective view. Detailed description of embodiments

[0039] Fig. Figure 15 illustrates an arc welding machine 70. The arc welding machine 70 has a torch head 10, the detailed design of which will be explained in more detail with reference to the other figures and in Fig. Figure 15 is only a simplified representation. The torch head 10 is connected to a power supply 72, a wire feeder 74 (which feeds a welding electrode 76), and a shielding gas supply 78. The welding electrode 76 is held in the torch head 10. However, the welding electrode 76 can also be a non-consumable electrode. In this case, the wire feeder 74 is not required. The torch head 10 described below is suitable for both MIG / MAG and TIG welding. The following examples of magnetic influence on the welding process refer to conventional MIG / MAG welding, in which the welding electrode 76 is positively charged and the workpiece is negatively charged. This is also known as MIG / MAG DCEP welding. In TIG welding and so-called MIG / MAG DCEN welding, the charge is reversed, resulting in a different influence.A similar or identical effect to the examples described here can result from a reversed polarity of the respective electromagnets.

[0040] Fig. Figure 1 illustrates, in a schematic perspective view, the torch head 10 for an arc welding machine 70 during a welding process. An arc generated at the welding electrode 76 melts a workpiece below the torch head 10, creating a weld pool 12 and producing the weld seam 90 shown here. The outer surface of the torch head 10 is formed by a sleeve 14, which is cylindrical in the example shown. Alternatively, the sleeve 14 can also be conical towards the weld pool 12 and thus towards a free welding-side end, in order to form a nozzle for a shielding gas.

[0041] In Fig. Figure 2 shows the torch head 10 without the sleeve 14, revealing the internal structure of the torch head 10. The torch head 10 has an axially extending contact tube 16 in which the welding electrode 76 is provided for the welding process. The contact tube 16 connects the welding electrode 76 to the power supply 72 of the arc welding machine 70. The welding electrode 76 is melted during the MIG / MAG welding process shown and is designed as welding wire. During the welding process, the welding electrode 76 is advanced through the contact tube 16 by the wire feed device 74.

[0042] The sleeve 14 radially surrounds the contact tube 16 on its outer side, forming an annular gap between the sleeve 14 and the contact tube 16. Between the sleeve 14 and the contact tube 16, four electromagnets 18 are symmetrically arranged in a plane extending radially to the contact tube 16 at the welding-side end region of the torch head 10. These electromagnets belong to an arc-controlling device of the torch head 10. The arc-controlling device with the four electromagnets 18 is designed to magnetically influence a generated arc during the welding process. In one embodiment, the arc-controlling device is designed to passively reduce arc instability by inducing a current flow into the four electromagnets 18 through the arc. This generates magnetic fields that counteract fluctuations in the shape and rotation of the arc.This allows the arc to self-regulate without requiring active control intervention. Alternatively or additionally, in one embodiment, the arc control device is designed to actively influence the arc by energizing the four electromagnets 18. Various control modes will be described later with reference to the following. Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13 to Fig. 14 explained.

[0043] The four electromagnets 18 can be manually pivoted within the radial plane by means of a pivoting device. One end of each electromagnet 18 is non-rotatably connected to a rod 20. These rods 20 are rotatably mounted on a guide plate 22, which is located in an end region of the torch head 10 opposite the welding end. Each rod 20 forms an axial pivot axis for the electromagnet 18 attached to it and optionally connects the electromagnets to a power source. The rods 20 are axially movable on the guide plate 22 to allow the electromagnets 18 to be axially displaced, as will be described below. A control element 24 in the form of a knob is mounted on the guide plate 22 and extends radially to an outer surface of the torch head 10 through a gap running along the circumference of the sleeve 14.This allows the user to manually adjust the orientation of the poles, and thus the end of each electromagnet 18 facing away from the rod 20, relative to the contact tube 16. The end of the electromagnets 18 facing away from the rod 20 is also connected to the power source via a line 36 if the electromagnets 18 are to be energized. These lines 36 are optionally provided with electrical insulation, as shown here. Alternatively or additionally, the guide plate 22 can be electrically insulating. The lines 36 are guided through the guide plate 22 along an associated guide track 50, so that the position of each line 36 can shift accordingly when the electromagnets 18 are pivoted within the guide plate 22. Furthermore, the guide plate 22 has through-holes for supplying shielding gas to the welding point. Fig. The design of the swiveling device shown in section 2 requires very few and simple parts.

[0044] Alternatively, the electromagnets 18 can also be mounted only at one end in the torch head 10. On a side of the guide plate 22 facing away from the welding end, an additional fixed guide plate 92 can be arranged axially spaced from the guide plate 22, either alternatively or additionally. Such an embodiment, which is otherwise similar to the embodiment of Fig. 2 is, is in Fig. 19 shown. This additional feature in the embodiment of Fig. The guide plate 92 shown in Figure 19, unlike the guide plate 22, is not rotatable but fixed to the contact tube 16. This additional guide plate 92 also has guide tracks for the conductors 36 to further stabilize a pivoting movement of the electromagnets 18. In addition to the guide tracks, the additional guide plate 92 also has openings for the protective gas flow.

[0045] In another embodiment, which in Fig. As shown in Figure 16, the rods 20 are each axially displaceable but rotationally fixed on an associated gear 54. These gears 54 mesh with a central gear 56, which is rotatably mounted on the contact tube 16. The central gear 56 is operatively connected to the control element 24, which is also designed as a gear and meshes with the central gear 56. This allows the electromagnets 18 to be pivoted particularly quickly or particularly precisely, depending on the gear ratio of the operative connection. The central gear 56 also has axial through-openings for the flow of protective gas.

[0046] Fig. 3 and Fig. Figure 6 shows a first pivoting position of the electromagnets 18, in which their free end was pivoted maximally outwards towards an inner wall of the sleeve 14. Fig. 3 and Fig. Figure 6 also shows that the electromagnets 18 are curved between their two ends and thus their two poles, with this curvature following an inner contour of the sleeve 14 in the first position. This allows the electromagnets 18, or rather their coils 30, to be particularly long, enabling them to be very powerful despite the limited space in the burner head 10. In other embodiments, the electromagnets 18 are straight. Furthermore, the electromagnets 18 can be pivoted outwards to a considerable extent. In the first pivoted position, the electromagnets 18 are far removed from the arc, and the magnetic field lines are aligned in such a way that there is very little influence on the arc. The arc interference can thus be manually deactivated mechanically.Overall, the arc control can be adjusted quickly and intuitively by an operator, without the need for electrical components or their operation.

[0047] Fig. 4 and Fig. Figure 7 shows a second pivoting position of the electromagnets 18, in which their free end and the pole there are aligned directly with the contact tube 16 and thus with the arc and the welding electrode 76. Compared to the first position, the electromagnets 18 are pivoted approximately 90° in the second position.

[0048] Fig. Figure 5 shows a third position in which the electromagnets 18 have been pivoted to their maximum extent relative to the first position, here by approximately 115°. In the third position, rotation of the arc can be particularly effectively induced or counteracted.

[0049] The four electromagnets 18 can be manually repositioned axially relative to a welding-side end of the torch head 10 along an axial axis of the torch head 10, and thus parallel to the axial extent of the contact tube 16, by means of a repositioning device. For this purpose, a plate, which also forms a heat shield 28, is manually displaced axially via a rack and pinion by means of a control element designed as a gear 26, with the electromagnets 18 being arranged on this plate or the heat shield 28. The electromagnets 18 are mounted in the torch head 10 by means of an axially central retaining ring 58. Alternatively, the electromagnets 18 can also be mounted on another component, such as the heat shield 28 or the contact tube 16. In addition to the plate, the heat shield 28 can also have a retaining ring, as shown.The plate and the retaining ring are designed in two parts, allowing the plate to be easily replaced if damaged. Alternatively, the plate and the retaining ring can also be manufactured as a single, cost-effective unit. The gear 26 extends radially through the opening in the sleeve 14 to an outer surface of the burner head 10. This allows the user to manually adjust the translational position of the electromagnets 18 and thus their axial distance to the arc. By adjusting this distance, the degree of influence on the arc can be set independently of whether the electromagnets 18 are energized. For example, the degree of passive reduction of arc instabilities can also be varied.

[0050] The retaining ring 58 engages with the rods 20, such that an axial displacement of the retaining ring 58 causes an axial displacement of the rods 20 and thus of the electromagnets 18. The retaining ring 58 is axially displaceable relative to the contact tube 16 by the operating element 26. The retaining ring 58 is at least axially connected to the rack into which the operating element 26 engages. For example, in the embodiment of Fig. 2 and Fig. 18 rotate relative to this rack. In other embodiments, the retaining ring 58 is formed integrally with this rack or permanently connected, for example by a rivet. For example, in the embodiment of Fig. 16 and also other embodiments with gears for pivoting the electromagnets 18, the retaining ring 58 is fixed to the rack for axial displacement of the electromagnets 18. In the embodiment of Fig. The rack is riveted and / or glued to the retaining ring 58 (item 16). Fig. 6 and Fig. Figure 7 does not show the retaining ring 58 so that the positioning of the electromagnets 18 can be better seen.

[0051] The electromagnets 18 each have a coil 30 wound around a core 34 made of ferromagnetic material, such as iron. The core 34 is provided with an electrically insulating ceramic coating on its outer circumference facing the coil 30. The coil 30, however, is free of electrical insulation, at least in the area where it is wound around the core 34. This makes the electromagnets 18 particularly heat-resistant. For example, the coil 30 in the area of ​​the core 34 can be made of an electrically conductive metal and thus withstand higher temperatures compared to a coil with a plastic insulating layer. Furthermore, the wire diameter of the coils 30 can be chosen to be particularly thick. This prevents excessive heating of the coils 30 due to current flow. For example, the coils 30 can be subjected to currents of up to 10 A without risk of damage.

[0052] The torch head 10 incorporates the heat shield 28 with its plate. The heat shield 28 is located on the welding side, and thus on the side of the electromagnets 18 facing the arc. The heat shield 28 at least partially shields the electromagnets 18 from heat from the arc and spatter from the welding process. The heat shield 28 has a central through-opening for the contact tube 16 and is guided by the contact tube 16 during axial movement. In a radially inner region, the heat shield 28 is continuous and may optionally have a thickened section. In a radially outer region, the heat shield 28 is formed as a continuous ring. The radially outer region and the radially inner region are connected by four radially extending ribs. In the circumferential direction, between adjacent ribs, the heat shield 28 has a through-opening through which shielding gas can flow to the weld area.The heat shield plate 28 is formed in one piece. The number of ribs, as well as their size and the number of openings, can be adapted to the required shielding gas flow and also to the number of electromagnets 18.

[0053] The protective gas can cool the electromagnets 18. In the first position, as in Fig. As can be clearly seen in Figure 3, the four electromagnets 18 are protected over a large area by the radially outer region from heat radiation and backsplash. In the second position, as in Figure 3, the four electromagnets 18 are protected from heat radiation and backsplash by the radial outer area. Fig. As can be seen in Figure 4, the four electromagnets 18 are extensively protected from heat radiation and splashback by the radially extending ribs. In the third position, the electromagnets 18 are also well covered from the perspective of the arc, both by the radially extending ribs and the radially inner area. Despite the opening, the design of the heat shield ensures good protection for the electromagnets 18 in every position.

[0054] The arc welding machine 70 can be configured to supply current to the electromagnets 18. Different operating modes can be set. These modes can be set automatically and / or manually. For example, a current direction can be specified for each operating mode at each electromagnet 18 in the coil 30, thus determining whether the free end of the electromagnets 18 forms the north or south pole of the generated magnetic field. The orientation of the magnetic field, with its north and south poles, is specified in the Fig. 8 to Fig. 14 each illustrated by an "N" and an "S". The exemplary operating modes illustrated in the Fig. 8 to Fig. 11 each utilize the second position of the electromagnets 18. The operating modes illustrated by example in the Fig. 12 and Fig. 13 each utilize the third position of the electromagnets 18. In other operating modes, the electromagnets 18 can be positioned differently. The current strength can be manually set, fixed, or automatically adjusted to the current strength of the welding electrode 76 in each operating mode.

[0055] In Fig. All electromagnets 18 have the same polarity. The electromagnets 18 are energized such that the north pole of each faces the contact tube 16 and thus the arc. This results in tangential magnetic forces which counteract unwanted rotation of the arc or by means of which rotation can be induced in the arc for improved droplet detachment.

[0056] In Fig. 9. All electromagnets 18 have the same polarity, and the electromagnets 18 are energized such that their south poles face the contact tube 16 and thus the arc. This results in tangential magnetic forces which improve droplet detachment during the welding process by means of additional tangential forces or by means of which unwanted rotation of the arc can be suppressed.

[0057] In Fig. In the 10th case, the electromagnets 18 have alternating polarities. Two of the electromagnets 18 are energized such that their north poles face the contact tube 16 and thus the arc. Two other electromagnets 18 are energized such that their south poles face the contact tube 16 and thus the arc. Two south poles are circumferentially adjacent to each north pole, and vice versa. This results in an expansion of the arc along one axis and a compression along another axis, with each axis extending radially between two circumferentially adjacent electromagnets 18. The arc can thus be deformed into an elliptical shape. Fig. In 11, only the order of the alternating polarity is reversed, so that the orientation of the elliptical influence of the arc is reversed.

[0058] In Fig. In 12, all electromagnets 18 have the same polarity. The electromagnets 18 are energized such that the north pole of each faces the contact tube 16 and thus the arc. However, the north pole and the free end of the electromagnets 18 do not each point directly at the arc, as in Fig. 8. In this operating mode, the electromagnets 18 are pivoted into the third position, whereby the free end of the electromagnets 18, and thus also the north pole, are essentially tangentially aligned with the contact tube 16 and therefore with the arc. The magnetic field thus generated exerts a force on the arc, which induces a rotational momentum. In addition, the arc is concentrated or focused. This can result in a small melt pool and good droplet detachment.

[0059] In Fig. 13 is the position of the electromagnets 18 as in the Fig. 12 and all electromagnets 18 have the same polarity. The electromagnets 18 are now energized such that the south pole of each faces the contact tube 16 and thus the arc, with the orientation also being tangential. The magnetic field thus generated exerts a force on the arc, which induces a rotational momentum. In addition, the arc is expanded. A large-area melt pool 12 can result.

[0060] In Fig. In step 14, the electromagnets 18 are each aligned with the contact tube 16. However, only every other electromagnet 18 is energized in the circumferential direction. Two of the electromagnets are therefore unenergized or switched off. One of the energized electromagnets 18 is energized such that its south pole is aligned with the contact tube. Another of the energized electromagnets 18 is energized such that its north pole is aligned with the contact tube. This deflects the arc in a direction as shown in Fig. Figure 14 illustrates this with the arrow. This can be used particularly in non-transferred arc processes to deflect the arc in a specific direction and thus influence the droplet trajectory. This can be especially useful in additive welding. Similar effects can also be achieved, for example, with an odd number of electromagnets, which can easily produce an asymmetrical deflection.

[0061] In Fig. Figure 17 shows a further embodiment of the burner head 10, which is similar to the embodiment of Fig. 16. In this embodiment, the retaining ring 58 is formed integrally with the rack, which engages with the operating element 26. Furthermore, the heat shield 28 is spaced apart from a free end of the contact tube. This allows the shielding gas to flow into the central through-opening in the plate of the heat shield 28 and directly around a free end of the welding electrode 76.

[0062] In Fig. Figure 18 shows a further embodiment of the burner head 10, which is similar to the embodiment of Fig. 2. In this embodiment as well, the heat shield 28 is spaced apart from a free end of the contact tube 16. This allows the shielding gas to flow into the central through-opening in the plate of the heat shield 28 and directly around the free end of the welding electrode 76. In this embodiment, the heat shield 28 is axially spaced apart from the contact tube 16 in every axial position of the electromagnets 18. In other embodiments, the electromagnets 18, and thus the heat shield 28, can be displaced to an axial position in which the heat shield 28 overlaps the contact tube 16. For example, Fig. 18 also do not show a further embodiment, but a different axial position of the embodiment of Fig. 2. In other embodiments, only axial aspects of the electromagnets 18 are adjustable, in which the heat shield 28 overlaps the contact tube 16. Reference sign 10 burner head 12 Melt bath 14 Sleeve / Nozzle 16 contact tube 18 Electromagnet 20 bars 22 Guide plate 24 Control element for swiveling the electromagnets 26 Control element / gear for axial displacement of electromagnets 28 Heat shield 30 coil 34 core 36 Management 50 Guide rail 54 gear 56 Central gear 58 retaining ring 70 arc welding machine 72 Energy supply 74 Wire feed direction 76 Welding electrode 78 Shielding gas supply device 90 weld seam 92 Guide plate

Claims

[1] Burner head (10) for an arc welding machine (70) with a contact tube (16) which is designed to provide a welding electrode (76) during a welding process, a sleeve (14) which radially surrounds the contact tube (16) on the outside, and an arc control device which has at least one electromagnet (18) and is designed to magnetically influence a generated arc during the welding process, wherein the electromagnet (18) is arranged radially between the contact tube (16) and the sleeve (14) in a welding-side end region of the torch head (10), wherein the arc control device has a pivoting device which is designed to pivot the electromagnet (18) for an alignment of the poles of the electromagnet relative to the contact tube (16). [2] Burner head (10) according to claim 1, wherein the burner head (10) is designed for supplying shielding gas during the welding process between the contact tube (16) and the sleeve (14). [3] Burner head (10) according to claim 1 or 2, wherein the arc control device is configured to passively reduce arc instability. [4] Burner head (10) according to any one of the preceding claims, wherein the pivoting device is designed to pivot the electromagnet (18) in a plane which extends radially to the contact tube (16) and / or wherein the pivoting device is designed for manual pivoting of the electromagnet (18) from outside the sleeve (14). [5] Burner head (10) according to any one of the preceding claims, wherein the arc control device has a displacement device which is designed to displace the electromagnet (18) axially relative to a welding-side end of the torch head (10), in particular along an axis which extends parallel to the contact tube (16) and / or in particular wherein the relocation device is designed for manual relocation of the electromagnet (18) from outside the sleeve (14). [6] Burner head (10) according to any one of the preceding claims, wherein the burner head has a (10) heat shield (28) which is arranged on the welding side towards the electromagnet (18), in particular wherein the heat shield (28) is arranged radially between the contact tube (16) and the sleeve (14) in a welding-side end region of the torch head (10). [7] Burner head (10) according to any one of the preceding claims, the electromagnet (18) comprises a coil (30), a core (34) and an electrical insulation arranged between them, in particular wherein the electrical insulation is formed by a coating on the core (34) and / or in particular wherein the coil (30) is free from an electrically insulating coating. [8] Burner head (10) according to any one of the preceding claims, the electromagnet (18) is curved, in particular wherein the curvature of the electromagnet (18) corresponds to a curvature of an inner circumference of the sleeve (14) facing the contact tube (16). [9] Arc welding apparatus (70) with an electrical power supply (72) and at least one torch head (10) according to one of the preceding claims, wherein the electrical power supply (72) is electrically connected to the contact tube (16). [10] Arc welding apparatus (70) according to claim 9, wherein the arc welding device (70) is designed to provide energy to the electromagnet (18) of the arc control device. in particular wherein the energy supply of the electromagnet (18) is adjustable.

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