Welding device with a welding torch and with a device and a method for determining and outputting the surface temperature of the welding torch

Abstract

Welding device (20) with a welding torch (10) for thermal joining of at least one workpiece, in particular for arc joining, preferably for arc welding or arc brazing, with a device (4) for determining and outputting the surface temperature of at least one area (3) of the welding torch (10), characterized in that the output, depending on the measured surface temperature, is additionally provided via an optical signal by means of a temperature visualization on the torch neck (6) of the welding torch (10) by means of thermochromatic material attached to the torch neck (6) of the welding torch (10).

Description

[0001] The invention relates to a welding device with a welding torch for thermally joining at least one workpiece, in particular for arc joining, preferably for arc welding or arc brazing, with a device for determining and outputting the surface temperature of at least one area of ​​the welding torch according to claim 1, and to a method for determining and / or monitoring the surface temperature of at least one area of ​​a welding torch according to claim 11.

[0002] Thermal joining processes use energy to melt and join workpieces. MIG, MAG, and TIG welding are standard techniques in sheet metal production.

[0003] In gas-assisted arc welding processes with consumable electrodes (MIG), "MIG" stands for "metal inert gas" and "MAG" for "metal active gas." In gas-assisted arc welding processes with non-consumable electrodes (TIG), "TIG" stands for "tungsten inert gas." The welding devices according to the invention can be designed as machine-guided welding torches mounted on a robot arm.

[0004] In general, arc welding devices create an arc between the workpiece and a consumable or non-consumable welding electrode to melt the weld metal.

[0005] The weld metal and the weld area are shielded from the atmospheric gases by a shielding gas flow.

[0006] The welding electrode is attached to the torch body of a welding torch connected to an arc welder. The torch body typically contains a group of internal, current-carrying components that conduct the welding current from a welding power source in the arc welder to the tip of the torch head on the welding electrode, from where it then generates the arc to the workpiece.

[0007] The shielding gas stream flows around the welding electrode, the arc, the weld pool, and the heat-affected zone on the workpiece, and is delivered to these areas via the torch body. A gas nozzle directs the shielding gas stream to the front end of the torch head, where the shielding gas stream exits the torch head in a roughly circular pattern around the welding electrode.

[0008] During the welding process, the arc generated for welding heats the workpiece to be welded and any weld metal added, so that they are melted.

[0009] In addition to welding, brazing can also be considered for joining sheet metal components. Unlike welding, it is not the workpiece that is melted, but only the filler metal. This is because brazing joins two edges together using the filler metal. The melting points of the filler metal and the component materials are far apart, which is why only the filler metal melts during processing. In addition to TIG, plasma, and MIG torches, lasers are also suitable for brazing.

[0010] Arc brazing processes can be divided into metal inert gas (MIG-L) and tungsten inert gas (TGM-L) brazing processes. Wire-shaped copper-based materials, whose melting points are lower than those of the base materials, are predominantly used as filler materials. The principle of MIG / MAG arc brazing is largely identical to MIG / MAG welding with wire-shaped filler materials, in terms of equipment.

[0011] As mentioned, such machine-controlled welding torches can be mounted on the robot arm of an industrial robot. In particular, it is conceivable that welding torches could be installed on so-called collaborative lightweight robots, known as cobots.

[0012] Such collaborative robotics applications are fundamentally changing the way humans and machines work together in the manufacturing sector. Human-robot collaboration (HRC) involves humans and machines working hand in hand. This collaboration enables manufacturers and industrial workers to combine the strength, reproducibility, and continuity of machines with the flexibility, adaptability, and intelligence of humans. As a result, production efficiency and flexibility in industrial processes can be significantly increased.

[0013] Humans control and monitor production, while robots can take over physically demanding tasks such as overhead work, lifting heavy loads, or even welding processes.

[0014] While just a few years ago, the field of robotics was primarily dominated by industrial robots, today such robots also assist humans in welding processes. The robots are no longer always separated from humans by protective fences, for example, in a so-called cell, but there is also direct interaction between humans and robots.

[0015] Therefore, the design of human-robot collaboration plays a critical role in optimizing worker safety and ensuring compliance with regulations. A collaborative robot is only one part of a collaborative robotics application and does not comply with safety regulations on its own. Since direct interaction always poses a potential risk to the human partner, new requirements are placed on such systems.

[0016] While conventional industrial robots are characterized by speed, but also by their heavy mass and extreme rigidity, interactive robots, i.e., cobots, often have only a few kilograms of collision mass, rounded or foam-covered corners and edges, and are adapted to human-like working speeds to increase work safety and enable truly adaptive collaboration. Advances in these technologies reduce the need for safety cells. This, in turn, saves space and costs and enables more flexible use in the manufacturing sector.

[0017] The same requirement naturally also applies to all other automation components, such as welding devices with welding torches, which are operated by the cobot.

[0018] Today's standards—provided by the Robotic Industries Association and various safety standards institutes—provide guidelines on how robots and humans can work together to revolutionize productivity and safety in industrial operations.

[0019] According to the standards ANSI / RIA R15.06-2012 and ISO 10218 "Safety of Industrial Robots," the term "collaborative" describes an automatically operated robot system that shares a workspace with a human. The standards EN ISO 10218 "Industrial robots - Safety requirements," Parts 1 and 2, and ISO / TS 15066 "Robots and robotic devices - Collaborative robots" describe the protection principles of human-robot collaboration (HRC).

[0020] Particularly in the area of ​​welding processes, the use of cobots creates an increased potential for contact and therefore hazards for cobot operators, as unlike welders, they often work with cobots without special protective equipment during manual welding. This particularly applies to the cobots' training phase, known as teaching. During these work steps, the cobots are prepared and trained for the welding work processes on the one hand, and trained to work with humans on the other. This training can be achieved by manually moving the cobot to defined positions. In other words, the operator engages the cobot and moves it to a specific position.

[0021] Since the main advantage of cobots over conventional robots is that they can be programmed very quickly and easily, unlike conventional robot programming, contact with the cobot or its components is explicitly planned and occurs very frequently. In this context, the teaching process must be distinguished from the subsequent industrial welding process.

[0022] In welding applications, the challenge now is to ensure that the usually unprotected operator or programmer does not touch the welding components when they are already hot in order to avoid injuries.

[0023] From JP 2014-108 438 A, a welding torch with temperature monitoring is known, whereby the temperature of a cooling water circuit of a welding device is to be controlled depending on the temperature of the welding torch.

[0024] JP 2018-027 555 A discloses a welding torch with a sensor device for measuring the temperature of the welding torch. The measured temperature can be displayed on a screen.

[0025] Manual welding torches generally do not have warning labels attached to the torch itself, but are often only mentioned in the torch's operating instructions. This is particularly acceptable because welders wear gloves due to the high process temperature and radiation intensity, which also protect them when touching hot components.

[0026] For robot programmers, on the other hand, a warning is also not necessary, since contact with the robot or the welding torch is not intended.

[0027] If warning signs are placed about hot surfaces, this is usually done by means of pictorial hazard warnings nearby and presented in a very general way, ie the signs warn regardless of the current temperature.

[0028] Humans therefore have no safe way of determining whether cobot components can be touched during welding processes, and whether temperatures, especially on touch-sensitive cobot components, are so high that they could cause injury. This is critical if the operator or maintenance personnel, unlike welders, do not wear personal protective clothing.

[0029] Based on the disadvantages described above, the object of the invention is to further protect a welding device with a welding torch in such a way that injuries, in particular burns, to the operator of the device are avoided as far as possible.

[0030] This object is achieved with a welding device having a welding torch according to claim 1 and with a method for determining and / or monitoring the surface temperature of at least one region of the welding torch according to claim 11. Description of the invention

[0031] The invention relates to a welding device with a welding torch for thermally joining at least one workpiece, in particular for arc joining, preferably for arc welding or arc brazing, with a device for determining and outputting the surface temperature of at least one area of ​​the welding torch.

[0032] As mentioned above, human-robot collaboration (HRC) involves contact between so-called collaborative lightweight robots, or cobots, and humans. In particular, manual teaching of the cobots by humans is necessary. The actual welding process, however, is not performed manually but by the cobot.

[0033] For manual torches that are not attached to a robot but are controlled by an operator, existing standards only permit a temperature of 50°C at the handle of the welding torch. However, this standard does not apply to cobots. For this reason, temperature determination and monitoring are provided according to the invention. Furthermore, a warning signal is issued to the operator depending on the determined temperature.

[0034] The surface temperature determination and output device, which comprises, for example, a sensor, determines and / or monitors the surface temperature of at least one area of ​​the welding torch. The sensor can be arranged on the surface of the welding torch in the area to be analyzed, i.e., the sensor can touch the surface to be analyzed. Alternatively, it is also conceivable for the surface temperature of the welding torch to be determined contactlessly, for example, using infrared measurement. The temperature range to be measured can be, for example, between 0°C and 150°C.

[0035] Another option would be to measure electrical resistance to determine surface temperature, for example, using PT-100 sensors. A PT-100 is a platinum resistor with a nominal resistance of 100 Ω at a temperature of 0°C, as defined in IEC 751 (EN 60751). PT-100 resistance sensors are used for temperature measurements. Because PT-100 sensors are robust and largely immune to electrical interference, they offer several advantages over thermocouples, such as a wide temperature range from -200°C to 850°C, a nearly linear characteristic, and good accuracy.

[0036] In this way, the surface temperature at preferred manipulation points of the burner, especially the burner neck, is precisely determined.

[0037] In addition to cobots, it could also be used in conventional industrial robots to protect or warn maintenance personnel about hot components when changing wear parts or torches. This allows safe programming and maintenance work to be carried out on conventional robots.

[0038] According to the invention, the output is provided via an optical signal depending on the determined or measured surface temperature.

[0039] According to a further advantageous embodiment of the invention, the output is provided via an acoustic signal depending on the determined or measured surface temperature. Within the scope of the invention, it is also conceivable to enable the output via a vibration of the welding torch neck, thereby alerting the user to a danger due to excessively high temperatures.

[0040] The signals measured by the sensor can be transmitted to the output by means of an optical and / or acoustic signal via a transmission device, for example via a cable or contactlessly.

[0041] Particularly in the case of robot systems that are not enclosed, i.e. arranged in a cell, an optical warning can be provided in the form of a temperature visualization on the welding torch so that the operator is warned of hot parts on the robot and injuries due to burns are avoided as far as possible.

[0042] According to the invention, temperature visualization is carried out by means of thermochromatic material attached to the welding torch.

[0043] Thermochromic materials are known, for example, from DE 102012018813 A1. Thermochromism refers to the property of a material to change its color reversibly or irreversibly depending on temperature. This can occur through changes in intensity and / or wavelength maximum. These color changes are caused by changes in the molecular or crystal structure. This behavior is known, among other things, in the inorganic compounds rutile and zinc oxide, which change their color from white to yellow upon intense heating.

[0044] Representative examples and theoretical background on the mechanism of temperature-controlled color are described in Chromic Phenomena by P. Bamfield and M. I Hutchings (The Royal Society of Chemistry, 2010) and in Thermochromic Phenomena in Polymers by A. Seeboth and D. Lötzsch (Smithers Rapra Technology, 2008).

[0045] Thermochromic paints can be applied using temperature-measuring paint pens or by painting using brushing, spraying, or dipping. The measuring range of thermochromic paints can extend up to approximately 1300°C.

[0046] It is therefore conceivable to apply a thermochromatic material, such as a coating, to the neck of the welding torch. This would provide the torch operator with a visual warning if a certain temperature, such as 50°C, is exceeded. The thermochromatic material would then change color, for example, to a signal color.

[0047] A warning message initially hidden by the thermochromatic material, such as "Caution: Hot," "Hot," or similar, could also become visible at a certain temperature. It's also conceivable that the operator would recognize a specific message, such as "Cold," as long as the temperature doesn't exceed a certain value.

[0048] According to a further advantageous embodiment of the invention, the output can alternatively or additionally be provided by an acoustic signal emitted by a loudspeaker, preferably arranged on the welding torch or the holder, when a certain temperature is reached or exceeded on the torch or the robot. Since some cobots are also capable of communicating with the operator via voice, a loudspeaker on the cobot can alternatively or additionally be used to warn the device operator.

[0049] According to the invention, the output is provided by means of an optical signal at the torch neck of the welding torch.

[0050] According to a further advantageous embodiment of the invention, the output by means of an optical signal is provided on and / or in a holder, in particular for arranging the welding torch on a robot, preferably a collaborative robot (cobot), and / or on the robot and / or on the cell housing the robot.

[0051] In particular, it can be provided that the output is designed by means of an optical signal as a status display with at least two LEDs or a so-called multi-color LED for visualizing the surface temperature of the welding torch.

[0052] Typically, the automated welding torch is mounted on a robot arm using a bracket. This bracket can accommodate the torch using appropriate fasteners. For example, the torch can be screwed to the bracket. The bracket, along with the torch, can then be attached to the robot arm. This can be a cobot or a conventional robot.

[0053] As mentioned, the status indicator for visualizing the temperature can be provided on the mount, for example, or even mounted on it. This allows for easy retrofitting of existing devices. It is also conceivable for the display to be integrated into the mount, which provides better protection for the display.

[0054] The holder can have a so-called multi-function flange, which is characterized by the fact that it fulfills a dual function. In addition to attaching the torch, the multi-function flange also serves to control the movement of the welding torch. In particular, buttons for programming the robot movements and / or control buttons, including for the welding power source, can be provided on the multi-function flange. The buttons can, for example, enable communication with the robot or cobot and / or set so-called higher-level PLC waypoints and switch the welding process on or off. Furthermore, the above-mentioned mode, in which the operator engages the cobot and moves it to a specific position, can be triggered by one of the buttons, which simplifies manual teaching by humans.In addition, it is possible to control the wire feed and / or carry out a gas test using the control buttons.

[0055] In this case, the multifunctional flange can be substantially cylindrical, with first fastening means provided on a base surface of the flange for attachment to the robot arm. Second fastening means can be provided on the cover surface of the flange for attaching the welding torch to the multifunctional flange. Thus, in the assembled state, the flange is positioned between the robot arm and the welding torch.

[0056] The temperature visualization can be implemented by a display and / or a loudspeaker to emit a warning tone on the jacket or cylinder surface of the multifunctional flange so that it is easily perceptible by a robot operator.

[0057] According to a further advantageous embodiment of the invention, the at least one sensor is arranged in the region of the torch neck and / or the gas nozzle for the discharge of a shielding gas stream from a gas outlet of the gas nozzle of the welding torch. In this way, the temperature measurement takes place at those points on the torch that are particularly likely to be touched by an operator. These preferred manipulation points are essentially the torch neck in cobots and the area of ​​the gas nozzle in conventional robots. For this reason, the sensor can be located on the torch neck, particularly in grip-sensitive areas of the torch neck.

[0058] According to an independent idea of ​​the invention, a method is provided for determining and / or monitoring the surface temperature of at least one region of a welding torch for thermally joining at least one workpiece, in particular for arc joining, preferably for arc welding or arc brazing, in particular with a previously described welding device, wherein an optical and / or acoustic signal or a signal generated by vibration is output as a function of the surface temperature.

[0059] This allows for risk-free touching of the welding torch and also warns of possible damage caused by excessively high surface temperatures on the welding torch.

[0060] According to a first advantageous embodiment of the method according to the invention, the surface temperature in the region of the torch neck and / or in the region of the gas nozzle of the welding torch is determined and / or monitored.

[0061] According to a further advantageous embodiment of the invention, the surface temperature is determined in real time, in particular within a time interval of less than 1 / 10 of a second, and is output optically or acoustically.

[0062] Real time is defined as a time interval of less than 1 / 10 of a second for determining the surface temperature. The temperature, and thus the acutely prevailing hazard potential, is presented to the operator in real time via a visual status display. It is also conceivable that access to the robot, in enclosed systems, is denied during this short period. In this way, the operator is protected depending on the situation or warned in real time that touching hot components on the welding torch will lead to injury. On the other hand, the operator is visually indicated whether, for example, maintenance or programming work on the robot or welding torch is possible without any potential hazard.

[0063] Further objects, advantages, features, and possible applications of the present invention will become apparent from the following description of an exemplary embodiment with reference to the drawing. All described and / or illustrated features, individually or in any meaningful combination, constitute the subject matter of the present invention, regardless of their summary in the claims or their interrelationship.

[0064] Some of them are shown schematically: Fig. 1 a welding device arranged on a robot arm of a robot with a welding torch and with a sensor for measuring the temperature, Fig. 2 a detailed view of the welding torch with torch neck, holder and sensor, Fig. 3 a detailed view of a holder with optical signal output and Fig. 4 a detailed view of the bracket arranged on the robot arm.

[0065] In the following figures of the drawing, identical or equivalent components are provided with reference numerals based on an embodiment in order to improve readability.

[0066] Out of Fig. 1 shows a welding device 20 with a welding torch 10 for thermally joining at least one workpiece, in particular for arc joining, preferably for arc welding or arc brazing.

[0067] The welding device 20 has a device 4 for determining and indicating the surface temperature of at least one area of ​​the welding torch 10.

[0068] The device 4 of the welding torch 10 has at least one sensor 1 arranged on a torch neck 6 of the torch 10 for determining and / or monitoring the surface temperature of an area 3 of the welding torch 10.

[0069] In the present embodiment, the welding device 20 with the welding torch 10 is arranged on a robot 13, in particular on a robot arm, as Fig. 1 and Fig. 2 show.

[0070] In particular, the welding device 20 is attached to the robot 13 by means of a holder 2. The holder 2 is designed here as a so-called multifunctional flange 12, which fulfills a dual function. The multifunctional flange 12 serves, on the one hand, to attach the welding device 20 to the robot 13 and, on the other hand, to control the movement of the welding torch 10. In particular, buttons 9 for programming the robot movements and / or control buttons can be provided on the multifunctional flange 12. Fig. The buttons 9 shown in Figure 3 can, for example, enable communication with the robot or cobot and / or set so-called higher-level PLC waypoints, as well as switch the welding process on or off. Furthermore, the aforementioned mode, in which the operator engages the cobot and moves it to a specific position, can be triggered by one of the buttons 9, simplifying manual teaching by humans. Furthermore, the control buttons can be used to control the wire feed and / or perform a gas test.

[0071] In the present case, the multifunctional flange 12 is essentially cylindrical, with first fastening means provided on a base surface of the flange for attachment to the robot arm. Second fastening means are provided on the cover surface of the flange for attaching the welding torch to the multifunctional flange. Thus, in the assembled state, the flange is arranged between the robot arm and the welding torch 10.

[0072] The temperature visualization can be implemented by a display and / or a loudspeaker to emit a warning tone on the jacket or cylinder surface of the multifunctional flange so that it is easily perceptible by a robot operator.

[0073] The data measured by sensor 1 for determining and monitoring the surface temperature are forwarded to a signal output device 5 by means of a transmission device.

[0074] The transmission device is provided to convert the raw data measured by the sensor 1 into signals which can be transmitted as temperature values ​​on the one hand and serve as an input signal for the signal output device 5 on the other hand.

[0075] This signal output device 5 can have an optical 8 and / or acoustic signal output. Output via vibration of a part of the welding device 20 is also conceivable.

[0076] In the present embodiment, the optical signal output 8 is formed by a status display 11 for visualizing the temperature on and / or in the holder 2, in particular on / or in the multifunctional flange 12.

[0077] However, temperature visualization can also be provided on other parts of the welding torch 10.

[0078] As from Fig. As can be seen from Figure 3, the multifunctional flange 12 in this case has an optical signal output 8, which is designed as a status indicator 11. Depending on the temperature measured by the sensor 1 and forwarded to the signal output device 5, a corresponding optical signal is output to the operator via LEDs. The LEDs can be several single-color LEDs or so-called multicolor LEDs, which, for example, symbolize a specific temperature in the manner of a traffic light, i.e., in the colors red, yellow, and green, and warn the user of excessively high temperatures.

[0079] According to the invention, an acoustic signal output can also be provided, alternatively or additionally, for example, by means of a warning signal, so that the operator is acoustically warned, in particular, of excessively high temperatures. For example, a loudspeaker can be provided for emitting the acoustic warning signal, which can be arranged on the torch neck or on the multifunctional flange.

[0080] It can also be provided that when a predetermined temperature is reached in enclosed robots, the operating personnel are denied access to the cell with the robot.

[0081] As from Fig. As further shown in Figure 2, sensor 1 is provided in the area of ​​a torch neck 6 of the welding torch 10. This is because the operator of the robot 13 has no safe way of determining whether robot components can be touched safely and whether the temperatures, particularly on grip-sensitive components of the robot 13, are so high that they could cause injuries. Therefore, the surface temperature is monitored at preferred manipulation points, particularly the torch neck, and the information is transmitted to the operator.

[0082] Furthermore, an alternative or additional sensor 1 can be arranged in the area of ​​a gas nozzle for the discharge of a shielding gas stream from a gas outlet 14 of the gas nozzle 7 of the welding torch 10. In addition to the use in so-called cobots, the use in conventional robots is also conceivable. For this reason, maintenance personnel must be protected or warned from hot robot components during wear part or torch replacement processes.

[0083] The surface temperature measured by sensor 1 is processed in real time, i.e. less than 1 / 10 of a second, and output as an optical and / or acoustic signal.

[0084] Out of Fig. 4 shows the multifunctional flange 12 arranged on the robot 13, on which the welding device 20 with welding torch 10 is arranged by means of a holding element 15.

[0085] In addition to the temperature visualization described in the present embodiment, it is also conceivable that the temperature visualization is carried out by means of thermochromatic material attached to the welding torch.

[0086] As mentioned, thermochromism refers to the property of a material to change its color reversibly or irreversibly depending on temperature. This can occur either by changing the intensity and / or the wavelength maximum. Thermochromic inks can be applied using temperature-measuring ink pens or by painting using brushing, spraying, or dipping. The measuring range of thermochromic inks can extend up to approximately 1300°C.

[0087] It is therefore conceivable to apply a thermochromatic material, such as a coating, to the welding torch 10, particularly the torch neck. This provides the operator of the torch 10 with a visual warning when a certain temperature, such as 50°C, is exceeded. The thermochromatic material then changes color, for example, to a signal color.

[0088] A warning message initially hidden by the thermochromatic material, such as "Caution: Hot," "Hot," or similar, could also become visible at a certain temperature. It's also conceivable that the operator would recognize a specific warning, such as "Cold," as long as the temperature doesn't exceed a certain value. List of reference symbols 1 sensor 2 bracket 3 Welding torch area 4 Furnishings 5 Signal output device 6 burner neck 7 Gas nozzle 8 optical signal output 9 buttons 10 welding torches 11 Status display 12 Multifunctional flange 13 robots 14 Gas leak 15 Holding element 20 welding device

Claims

[1] Welding device (20) with a welding torch (10) for the thermal joining of at least one workpiece, in particular for arc joining, preferably for arc welding or arc soldering, with a device (4) for determining and outputting the surface temperature of at least one area (3) of the welding torch (10), characterized by that the output, depending on the measured surface temperature, is additionally provided via an optical signal by a temperature visualization on the torch neck (6) of the welding torch (10) by means of thermochromatic material attached to the torch neck (6) of the welding torch (10). [2] Welding device (20) according to claim 1, characterized by that the device (4) for determining the surface temperature has a sensor (1). [3] Welding device (20) according to claim 2, characterized by that the sensor (1) is arranged on the welding torch (10). [4] Welding device (20) according to claim 2, characterized by that the sensor (1) determines the surface temperature of the welding torch (10) without contact, in particular by means of infrared measurement. [5] Welding device (20) according to one of claims 1 to 4, characterized by that the output, depending on the measured surface temperature, is additionally provided via an acoustic signal and / or by vibration of a part of the welding torch. [6] Welding device (20) according to claim 1, characterized by that the output can be output by means of an optical signal (8) on and / or in a holder (2), in particular for arranging the welding torch (10) on a robot (13), preferably a collaborating robot (cobot), and / or on the torch neck (6) and / or on the robot (13) and / or on a cell enclosing the robot (13). [7] Welding device (20) according to claim 6, characterized bythat the output by means of optical signal (8) is designed as a status display (11) with at least two LEDs for visualizing the surface temperature of the welding torch. [8] Welding device (20) according to one of claims 2 to 4, 6 or 7, characterized by that the data measured by the sensor (1) is transmitted for output without contact or via cable. [9] Welding device (20) according to one of claims 2 to 8, characterized by that the at least one sensor (1) is arranged in the region of the torch neck (6) and / or the gas nozzle (7) of the welding torch (10). [10] Welding device (20) according to claim 5, characterized by that the output by means of an acoustic signal is formed by a warning tone emitted by a loudspeaker, preferably arranged on the welding torch (10) or the holder (2). [11] Method for determining the surface temperature of at least one region (3) of a welding torch (10) for the thermal joining of at least one workpiece, in particular for arc joining, preferably for arc welding or arc brazing, with a welding device (20) according to one of the preceding claims, wherein an optical and / or acoustic signal and / or a signal by means of vibration is output as a function of the surface temperature and wherein the surface temperature in the region of the torch neck (6) of the welding torch (10) is determined, wherein the output as a function of the measured surface temperature is additionally carried out via an optical signal by means of a temperature visualization on the torch neck (6) of the welding torch (10) by means of thermochromatic material attached to the torch neck (6) of the welding torch (10). [12] Method according to claim 11, characterized bythat the surface temperature is determined in real time, in particular within a time interval of less than 1 / 10 of a second, and is output optically or acoustically.

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