System for monitoring a welding process

Abstract

System for monitoring a weld seam (8) formed with a welding device (2) during a welding process on at least one component (4, 6), wherein the system (22, 42) comprises at least one acoustic sensor (28, 30, 32, 34, 36), at least one electrical sensor (38) and an evaluation unit (24), wherein the at least one acoustic sensor (28, 30, 32, 34, 36) is configured to measure structure-borne sound values ​​of the at least one component (4, 6), wherein the at least one electrical sensor (38) is configured to measure values ​​of at least one electrical operating parameter during the welding process, wherein the at least one evaluation unit (24) is configured to evaluate the weld seam (8) based on the measured values, wherein the at least one acoustic sensor (28, 30, 32, 34, 36) is additionally configured to measure structure-borne sound values ​​of at least one clamping device (10, 12, 14) trained component of the welding device (2),wherein the at least one clamping device (10, 12, 14) is designed to fix the at least one component (4, 6).

Description

[0001] The invention relates to a system for monitoring a welding process and a method for monitoring a welding process.

[0002] A great deal of effort is required to detect irregularities in a weld seam during a manufacturing process, with four possible approaches.

[0003] For example, it is possible for an employee to be scheduled and assigned to perform a visual inspection. The employee performs a visual inspection to examine the weld seam for external defects. A certain amount of time must be provided in the planning phase for the employee to complete the visual inspection. Furthermore, this procedure is highly subjective and dependent on the employee themselves. Furthermore, additional spaces or areas are usually required for this type of inspection. This leads to high overall investment and ongoing costs.

[0004] Alternatively, optical camera systems can be used. This approach also requires an additional process step, a test cell, a component handling device, and / or a robot, which in turn requires a lot of space and incurs significant additional costs. The systems required for this are therefore very costly and can also only detect external seam defects.

[0005] Additional sensors can be positioned directly on a torch and could be, for example, a laser cutting sensor for seam tracking or a temperature profile scanner for detecting irregularities. The sensors can be placed or attached in the immediate vicinity of the torch. The laser cutting sensor is intended to ensure optimal seam tracking and thus prevent seam defects. This either requires an additional process step or restricts accessibility. However, this does not allow any conclusions to be drawn about the formation of irregularities in a weld seam. A thermal profile scanner designed for inline detection of seam irregularities also restricts accessibility to the torch, e.g., the welding torch. Clear detection of irregularities in a weld seam is therefore only possible to a limited extent.

[0006] It is also possible to conduct a destructive test (zP), such as a microsection test. While internal defects can be assessed, destructive testing cannot be performed on every component, assembly, or vehicle, but only in a predefined cycle. The more frequently destructive testing is performed, the less cost-effective it becomes. Furthermore, cyclical testing means that not all defects can be detected, since, for example, a microsection test is only a visual snapshot, and potential defects in the inspected weld itself remain undetected, as well as in uninspected welds.

[0007] The document DE 23 37 856 A describes a method for controlling a welding speed and a welding current by measuring a welding noise.

[0008] A method for detecting the wear condition of an electrode of a welding gun is known from the document DE 10 2011 118 419 A1.

[0009] The document DE 198 24 600 A1 describes a method for testing the quality of a weld seam that connects two metallic workpieces.

[0010] A method for monitoring a manufacturing process for producing a through hole is described in the document DE 10 2005 027 363 A1.

[0011] Furthermore, reference is made to the article “Monitoring and quality assurance of the laser welding process of ultra-high-strength car body steels using integrated NDT methods” by the authors Bastuck, Valeske, Wolter and Herrmann from the DGZfP Annual Conference 2013.

[0012] A sound-based method for determining the position of a welding torch is known from the document US 2013 / 0208569 A1.

[0013] The document EP 2 549 833 A1 describes a method for operating an arc furnace operated with an alternating voltage.

[0014] US Pat. No. 5,306,893 A describes a system for real-time analysis of weld quality in an arc welding process. This system records acoustic signals from a component being welded.

[0015] Document AT 517 235 A4 describes a method for displaying or controlling the operating state of an outlet nozzle for a cutting or cutting-assisting working gas of a cutting torch. A vibration sensor detects vibrations that occur during operation of the cutting torch.

[0016] Against this background, one task was to assess the condition of a weld seam connecting components.

[0017] This problem is solved by a system and a method having the features of the independent patent claims. Embodiments of the system and method are evident from the dependent patent claims and the description.

[0018] The system according to the invention is designed to monitor, for example to assess, a weld seam that is formed by welding with a welding device during a welding process on at least one component when the at least one component is being welded. The system has at least one sound sensor, at least one electrical sensor and an evaluation unit, wherein the at least one sound sensor is designed to measure and / or detect values ​​of structure-borne sound of the at least one component during welding. The at least one electrical sensor is designed to measure and / or detect values ​​of at least one electrical operating parameter during the welding process or during welding. The at least one evaluation unit is designed to evaluate the weld seam based on the detected and / or measured values.The at least one sound sensor is additionally designed to measure and / or detect, in addition to values ​​for the frequency and / or amplitude of the structure-borne sound of the at least one component, also values ​​of a structure-borne sound of at least one component of the welding device designed as a clamping device, wherein the at least one clamping device is designed to fix the at least one component.

[0019] The structure-borne sound measured here and the at least one electrical operating parameter have a frequency and an amplitude as aspects that are determined here, whereby the welding process is assessed based on a respectively recorded actual value of the frequency and / or amplitude of the structure-borne sound. Furthermore, a phase angle and a pulse width can be considered as aspects of the structure-borne sound and the at least one electrical operating parameter.

[0020] Typically, the at least one electrical sensor is designed to measure and / or detect values ​​for the frequency and / or amplitude of an electrical current and / or an electrical voltage as the at least one electrical operating parameter.

[0021] Furthermore, the at least one sound sensor is additionally designed to measure and / or detect values ​​of a structure-borne sound of at least one further component of the welding device.

[0022] The method according to the invention is provided for monitoring, for example, for assessing, a weld seam formed by welding with a welding device during a welding process on at least one component when the at least one component is being welded. At least one sound sensor measures and / or records values ​​of structure-borne sound of the at least one component during welding. Furthermore, at least one electrical sensor measures and / or records values ​​of at least one electrical operating parameter during the welding process or during welding of the at least one component. The weld seam is evaluated by an evaluation unit based on the recorded and / or measured values.

[0023] An actual value of the frequency, amplitude, phase angle and / or pulse width of the structure-borne sound and of the at least one electrical operating parameter are compared with a respective intended and / or defined target value. In the method, values ​​or corresponding signals, e.g. signals that represent and / or include such values, i.e. values ​​of the structure-borne sound and of the at least one electrical operating parameter, can be evaluated and based on which the weld seam can also be monitored and evaluated during the welding process. Since the values ​​of the structure-borne sound and of the at least one electrical operating parameter each have a welding process-dependent frequency, amplitude, phase position and / or pulse width, Fourier transformations can also be used to evaluate them.

[0024] The at least one sound sensor, for example at least one first sound sensor, is connected to the at least one component at least temporarily and detachably again and / or arranged on the at least one component at least temporarily and detachably again.

[0025] In addition, the at least one sound sensor, for example, at least one second sound sensor, can be connected to at least one component of the welding device at least temporarily and detachably or permanently and / or arranged on the at least one component at least temporarily and detachably or permanently. Such a component of the welding device is designed as a clamping device for fastening and / or fixing the at least one component.

[0026] In one embodiment, for example, a warning signal is generated by the evaluation unit if at least one detected and / or measured value of the frequency and / or the amplitude of the structure-borne sound, the current and / or the voltage deviates from a respective target value by a respective tolerance value provided for this purpose, wherein the welding process can also be aborted depending on the deviation of an actual value from the respective target value.

[0027] The presented system is intended for a welding device or arrangement and is designed to detect irregularities in a weld seam and / or in a welding process, e.g. during arc welding. With one embodiment of the system and by carrying out one embodiment of the presented method, it is possible to acoustically and electrically detect and determine any defects within the weld seam while the welding process is still in progress using the sensors, i.e. the at least one sound sensor and the at least one electrical sensor. Within the scope of an assessment and / or evaluation to be carried out when monitoring the welding process and the weld seam, the latter can be assessed or evaluated as "OK" if a correct and therefore defect-free weld seam is detected and thus determined using the sensors.If the weld seam is found to have at least one defect, which can be detected using the sensors, the weld seam is evaluated and / or assessed as "defective." During the welding process, metal components or workpieces, such as sheet metal, are typically welded together and joined via the weld seam as a welded joint.

[0028] The welding device comprises, in its design, as components, in addition to at least one clamping device, an arc welding module as a torch and a manipulator, for example a robot, for moving the arc welding module along a predetermined movement path of at least one workpiece or component to be processed, i.e. at least one workpiece or component to be welded, and at least one electrical sensor or electric sensor for recording measured values ​​or corresponding signals of the current and / or voltage during arc welding. The at least one acoustic sensor or sound sensor designed as a structure-borne sound sensor, for example a microphone, is provided for recording measured values ​​of the structure-borne sound generated in the at least one component during arc welding. The automatic evaluation unit is provided for determining the measured values ​​or signals, at least on the basis of the measured values ​​or signals.The at least one sound sensor, e.g., a structure-borne sound sensor, is arranged directly on the part and component, e.g., on the clamping device, on the torch configured, for example, as an arc welding module, and / or on the manipulator or robot of the welding device. The welding device has, as a further component, a component holder for workpieces or components to be machined, wherein the at least one structure-borne sound sensor can also be arranged on the component holder.

[0029] The at least one sound sensor, designed as a structure-borne sound sensor, is intended to be temporarily connected to a workpiece to be machined, e.g., directly attached to it. The automatic evaluation system is designed to generate a warning signal if at least one evaluation criterion determined during the process lies outside a specified tolerance range, i.e., if at least one recorded value or measured value deviates from the specified threshold value by the specified tolerance value.

[0030] Furthermore, the automatic evaluation system, which can also be designed or referred to as a monitoring and / or evaluation system, is designed to evaluate the weld seam created, for example, during arc welding, taking into account the temporal correlation of the measured values ​​of structure-borne sound, current, and / or voltage, e.g., their frequency and / or amplitude. Furthermore, the system can have additional sensors for recording further process data or operating parameters, with the automatic evaluation system being designed to take these into account when evaluating the weld seam created during arc welding.

[0031] The system therefore comprises several sensors that enable external and internal defects in the weld seam to be detected acoustically and electrically, without necessarily affecting or restricting the accessibility of a torch as a component of the welding fixture. During monitoring, the system enables the evaluation of the weld seam by combining several different sensor-detected operating parameters, process and joining data, and their intelligent evaluation. This includes recording current and / or voltage values ​​from the welding fixture or welding system, as well as recording sound emission values, particularly structure-borne sound.

[0032] The at least one structure-borne sound sensor is, for example, a piezoelectric acceleration sensor whose design is based on the transverse effect. Piezoelectric elements of such a structure-borne sound sensor are, for example, encapsulated in a heat-resistant housing. A support surface of the structure-borne sound sensor can be made of ceramic or another material for coupling or arrangement to a corresponding object, e.g. the component, the arc welding module, or the manipulator designed, for example, as a robot, which excludes and / or suppresses electrical interference occurring between the object and the structure-borne sound sensor. The number of structure-borne sound sensors depends, among other things, on the component or an assembly of components, the length of a weld seam, the number of weld seams, the distances between weld seams, as well as the welding device and its component holder.

[0033] With regard to current and / or voltage consumption, the electrical current is detected, for example, by a series connection of a compensation transformer in a welding circuit of the welding device. This measurement is performed indirectly by recording values ​​of the magnetic flux density proportional to the electrical current via the Hall effect. The electrical voltage during welding is recorded, for example, between a front drive in the torch head and the clamping device as components of the welding device. Due to the available interfaces, an analog signal containing values ​​for the current and / or voltage is first recorded by a measuring cube. Alternatively, the current and voltage values ​​can be taken directly from the welding device and thus from a process device.

[0034] A preamplifier and / or signal converter is designed to amplify and / or filter signals for values ​​of the operating parameters to be recorded. If necessary, the sound sensor, e.g., a structure-borne sound sensor, is or will be coupled to the preamplifier. The preamplifier also serves to amplify and / or filter a voltage signal output by the respective sensor. The preamplifier can be installed as additional hardware or directly in a respective sensor, whereby the preamplifier and the sensor can be connected, for example, via a coaxial cable. The preamplifier can have an integrated high-pass filter with a suppression of up to 35 kHz, which can be activated as needed. The preamplifier can be connected, for example, via an Ethernet cable or another transmission path to the evaluation unit, which can be designed as a measuring computer.

[0035] The presented system includes the evaluation unit as well as a measuring unit and / or a computing unit, e.g. the measuring computer, and thus hardware for processing the incoming signals and data on the values ​​of the operating parameters to be recorded.

[0036] The evaluation unit with the measuring unit, e.g., the measurement computer, consists of all the necessary hardware components required to process the signals supplied by the sensors and / or preamplifiers for the operating parameters. The evaluation unit is equipped with sufficient input and output ports. These ports should also allow integration into the programmable logic controller (PLC) of a production process, in this case, the welding process. The evaluation unit also contains a hardware component, e.g., a measurement card, for processing the signals.

[0037] A system storage unit, for example, located in the evaluation unit, can ensure storage of the data and / or recorded values. The recorded data and / or values ​​can be stored either internally within the evaluation unit itself, e.g., via an integrated storage unit, and / or externally, e.g., via a cloud or external hard drive.

[0038] In addition, an evaluation unit with software for visualization and / or operation of the system and / or the welding device can be provided. The evaluation unit and software can be integrated directly into the measuring unit. Alternatively, visualization can also take place via a web API, a stationary screen, a telecommunications device, or other playback or communication devices.

[0039] The system also includes signal transmission elements, such as coaxial and / or Ethernet cables, for transmitting the signals from the sensors to the evaluation unit, e.g., the measurement computer. Alternative transmission options are also conceivable.

[0040] A power supply unit of the welding device is designed to adjust the at least one electrical operating parameter, ie the current and / or the voltage, wherein values ​​of the at least one electrical operating parameter resulting from the welding process are measured by the at least one electrical sensor.

[0041] The system can also be equipped with additional sensors. These can be designed to record additional values ​​or signals, e.g., airborne sound signals (acoustics), temperature, temperature profiles, position data and / or gap information, other component information, the amount of gas and wire required during welding, e.g., welding wire, information about the position of the robot (robot position and robot speed information), other information about the robot (robot information), for the visual detection of the weld seam, and / or emission signals.

[0042] Furthermore, the system can record other process and / or robot information. Such additional information can be taken as operating parameters directly from the welding fixture or process device and / or from the robot.

[0043] The method enables automated monitoring and evaluation of the quality of the weld seam and / or the welding process. Accessibility is not restricted by additional equipment or additional fittings on the welding torch as a component of the welding fixture. Internal and external irregularities of the weld seam are evaluated. No test scrap is generated. Cost-effectiveness is improved compared to visual assessment by humans or by optical camera systems with additional equipment.

[0044] The method can, for example, be carried out for a metal arc welding process, which is very complex as operating parameters due to the many joining parameters and influencing variables. During the welding process, a large number of signals and / or process data can be collected as operating parameters, and their measured values ​​can be viewed as a whole in order to draw conclusions about the joining quality or to carry out process control. An arc welding process is usually influenced by the reference variables current and voltage. A current and voltage analysis can be used to draw conclusions about the process stability or joining quality of the weld seam, whereby reproducible fault allocation for fault detection and process control is possible. The method can be supplemented by further process information, such asby additional detection of the temperature of the components and / or the weld seam or by visual detection of droplet detachment, so that a reliable, reproducible fault assignment can be achieved.

[0045] In the method, the structure-borne sound and at least one electrical operating parameter are measured, whereby it is possible to evaluate the weld seam formed during welding while the welding process is still in progress.

[0046] The sound sensor records vibration values ​​in the body of at least one component and converts them into a signal, e.g., in the form of an electrical voltage. This signal can then be modified using at least one Fourier transformation. The information thus obtained comprises an amplitude at a specific frequency of the structure-borne sound and time. The human audible range is between 0 and 20 kHz. Using structure-borne sound, much higher frequencies of up to 1500 kHz can be recorded and evaluated. For example, crack-like events, which are very short-term phenomena and barely or not at all audible to humans, can be detected at high frequencies. Thus, the welding process and the weld seam are monitored and assessed based on values ​​or corresponding signals for the frequency and / or amplitude of the structure-borne sound. This is where structure-borne sound offers an advantage.Using various evaluation options, such as pattern recognition, energy threshold analysis, or envelope analysis, the values ​​or signals for structure-borne sound can be compared. If a measured actual value of a structure-borne sound signal deviates from a specified target value by at least a tolerance value, this can be detected and the welding process stopped or aborted.

[0047] Values ​​for the frequency or amplitude of structure-borne sound, current, and / or voltage are usually compared and evaluated using threshold values ​​(envelopes). A phase angle and pulse width can also represent aspects of the structure-borne sound and at least one electrical operating parameter, in order to draw conclusions about the joining quality of the weld seam in addition to values ​​for the frequency or amplitude of the structure-borne sound, current, and / or voltage. Furthermore, the raw signals of the values ​​for the frequency or amplitude of the structure-borne sound, current, and / or voltage can also be subjected to at least one Fourier transformation to increase the information content regarding the frequencies and phase angles.

[0048] Some irregularities can be detected in specific signals, such as current or structure-borne noise. Therefore, the combination of multiple sensors and the signals they provide, or signals for current, voltage, and structure-borne noise, offers a higher probability of identifying irregularities, for example, according to the following scheme: - Error type A can be detected via signal 1 - Error type B can be detected via signal 2 - Error type C can be detected via signals 1 and 2

[0049] In addition, every measurement system has a measurement tolerance. Combining different signals or corresponding values ​​can significantly increase the accuracy of the results. If the error type or irregularity A is only detected 80% of the time by signal 1 and 70% of the time by signal 2, the combination still results in an increased probability of making the correct conclusion.

[0050] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0051] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0052] The invention is illustrated schematically in the drawings using embodiments and is described schematically and in detail with reference to the drawings. Fig. 1 shows a schematic representation of a first embodiment of the system according to the invention for carrying out a first embodiment of the method according to the invention in a welding process which is carried out by a welding device. Fig. 2 shows a schematic representation of a second embodiment of the system according to the invention for carrying out a second embodiment of the method according to the invention for a welding process which is carried out by the welding device.

[0053] The figures are described coherently and comprehensively; the same components are assigned the same reference symbols.

[0054] The Fig. The welding device 2 schematically shown in Figure 1 is designed to join a first component 4 and a second component 6 or corresponding metal workpieces to one another during the welding process, a weld seam 8 being formed between the two components 4, 6. The welding device 2 comprises as components a plurality of clamping devices 10, 12, 14 which are designed to clamp the two components 4, 6 and thus fix them to one another for carrying out the welding process. In this case, a clamping device 10, 12, 14 exerts a force F, indicated here by an arrow, on at least one of the two components 4, 6. The forces F exerted by the respective clamping devices 10, 12, 14 can be the same for at least two of the clamping devices 10, 12, 14 and / or different for at least two of the clamping devices 10, 12, 14.

[0055] The welding device 2 also comprises a torch 16, which is usually moved automatically along a predetermined movement path during the welding process, the torch 16 being designed to heat the components 4, 6, thereby forming the weld seam 8. Furthermore, the welding device 2 has, as a further component, an electrical energy source 18, for example a current source and / or voltage source, which is designed to provide the torch 16, which can be designed, for example, as an arc welding module, with electrical energy with which the welding process is carried out. The welding device 2 also has a robot 20 as a further component, which is designed to automatically move the torch 16 along the intended movement path during the welding process, the robot 20 also being supplied with electrical energy from the electrical energy source 18 for this purpose.

[0056] The first embodiment of the system 22 according to the invention comprises an evaluation unit 24, here, for example, a processing unit or a computer (PC), and an interface 26 with multiple inputs and outputs, which is designed here as an interface 26 for a local area network (LAN). Furthermore, the system 22 comprises a plurality of sensors, here sound sensors 28, 30, 32, 34, 36 as acoustic sensors and an electrical sensor 38 as an electrical sensor. The sound sensors 28, 30, 32, 34, 36 are designed, for example, as respective microphones to detect and / or measure structure-borne sound from at least one of the components 4, 8 and the components designed as clamping devices 10, 12, 14, here a respective actual value of a frequency and amplitude of the structure-borne sound.

[0057] For this purpose, a first sound sensor 28 is arranged directly on the first component 4 during the welding process, this first sound sensor 28 being in direct contact with the first component 4. A further corresponding sound sensor 28 (not shown here) can also be arranged on the second component 6 in some embodiments and can be in direct contact with the second component 6. With at least one such sound sensor 28, which is arranged directly on the at least one component 4, 6, values, i.e. actual values, of the frequency and amplitude of the structure-borne sound of the at least one component 4, 6 are measured or recorded during the welding process during which the weld seam 8 is formed and transmitted to the evaluation unit 4.

[0058] Furthermore, it is provided here that a respective clamping device 10, 12, 14 is also in direct contact with the at least one component 4, 6 during the welding process. A further sound sensor 32, 34, 36, which is connected to a respective clamping device 10, 12, 14 and / or is in contact with it, is designed to measure and / or record values, ie actual values, of the frequency and amplitude of structure-borne sound of the respective clamping device 10, 12, 14 as a component of the welding device 2 during the welding process and to transmit them to the evaluation unit 24.

[0059] The sensor, designed here as an electrical sensor 38, which can also be designed or referred to here as an electrical multimeter, is designed to measure or record values, i.e. actual values, for example a frequency and amplitude, of an electrical voltage U that is applied to at least one of the components 4, 6 and of an electrical current I that flows through at least one of the components 4, 6 during the welding process, and to transmit these values ​​to the evaluation unit 24. In this embodiment, it is possible for the electrical sensor 38 to be connected between the electrical energy source 18 of the welding device 2 and at least one of the two components 4, 6 and to be designed to measure values ​​of the electrical current that flows between the at least one component 4, 6 and the electrical energy source 18 during the welding process through the electrical sensor 38 as a current / voltage measuring device.

[0060] In this embodiment of the method, all values ​​of all acoustic and electrical operating parameters measured by sensors, i.e. values ​​of the structure-borne sound, the electrical voltage and the electrical current, usually the frequency and amplitude, are evaluated together by the evaluation unit 24, wherein the evaluation unit 24 is designed to assess and / or evaluate the weld seam 8 formed during the welding process and / or its quality on the basis of the determined values ​​for the operating parameters. In this embodiment of the method, it is provided that all values ​​of the operating parameters which are recorded at a specific point in time are evaluated together. It is provided that at least one actual value for at least one acoustic and / or electrical operating parameter, e.g.The frequency and amplitude of the respective operating parameter are compared with a specified setpoint. This check determines whether at least one measured value or actual value deviates from the setpoint by a specified tolerance value.

[0061] If the at least one value, e.g., for the frequency and amplitude, deviates from the target value by at most the respective specified tolerance value, the evaluation unit 24 determines that the weld seam 8 formed during the welding process is satisfactory. However, if the at least one value or actual value, e.g., for the frequency and amplitude, is greater than the threshold value plus the tolerance value or less than the threshold value minus the tolerance value, the evaluation unit 24 determines that the weld seam 8 formed during the welding process is defective and therefore not satisfactory.

[0062] In one embodiment, it is possible, using a respective provided formula, to calculate a so-called higher-level operating parameter by the evaluation unit 24 from several measured values ​​for different operating parameters, which are simultaneously measured or recorded by different sensors. This higher-level operating parameter is dependent on several different sensor-measured operating parameters or a combination of these operating parameters. In order to monitor, for example, to assess or evaluate whether the weld seam 8 formed during the welding process is satisfactory or not, in one embodiment of the method, the value of the higher-level operating parameter calculated from the values ​​of the individual operating parameters can be compared with a threshold value provided for this purpose, taking into account a tolerance value provided for this purpose.

[0063] In summary, the system 22 comprises sensors for detecting the structure-borne sound signal, sensors for current and voltage consumption, preamplifiers or signal converters for amplifying or filtering the signals for the measured values ​​of the operating parameters, the evaluation unit 24, e.g., the measuring computer or corresponding hardware for processing the incoming signals or data for the measured values, a storage unit as part of the evaluation unit 24, software for visualizing and / or operating the welding device 2 and the evaluation unit 24, signal transmission elements, such as coaxial and / or Ethernet cables, for transmitting the signals from the sensors to the evaluation unit 24, the energy source 18 as the power supply unit, other sensors for recording additional signals, and a possibility for recording other process and robot information by the evaluation unit 24.

[0064] The sound sensors 28, 30, 32, 34, 36 for detecting structure-borne sound signals can be mounted at different positions on at least one component 4, 6, whereby, depending on the task, different boundary conditions and target variables are defined as operating parameters for the welding process. Depending on the existing boundary conditions for the welding process, several sound sensors 28, 30, 32, 34, 36 are used.

[0065] At least one sensor, e.g., a sound sensor 28, 30, is mounted directly at a position of the at least one component 4, 6 to be joined. Interfaces, e.g., component transitions or transitions from one object, i.e., at least one component 4, 6 and / or at least one component of the welding device 2, to another object, are avoided or minimized. Interfaces between a sensor and an object can reduce the quality of a signal. Furthermore, air gaps between the at least one sensor of the welding device 2 and the component 4, 6 are completely avoided.

[0066] In one embodiment, the at least one sensor is attached or arranged with sufficient force to the respective object, i.e., the component 4, 6 and / or the component of the welding device 2. Furthermore, the position of the at least one sensor is selected such that it cannot be damaged by welding heat and / or welding spatter. The respective positioning ensures good transmission of the acoustic signals from the at least one component 4, 6 to the at least one sensor.

[0067] The Fig. The second embodiment of the system 42 according to the invention for the welding device 2 shown in Figure 2 has, in comparison to the first embodiment of the system 22 Fig.1 has, as an additional component, a sensor arrangement 44 or a corresponding sensor system comprising at least one sensor. This sensor arrangement 44 connects the robot 20, the evaluation unit 24, and the interface 26 to the electrical energy source 18 and is designed to measure at least one electrical operating parameter.

[0068] In an embodiment, at least one positioning of the at least one sensor is possible under three different positions relative to the at least one component 4, 6 and / or to at least one component of the welding device 2.

[0069] The at least one sound sensor 28, 30 is positioned according to a first positioning directly on the components 4, 6 to be joined and in the immediate vicinity of a joining point. The coupling of the at least one sound sensor 28, 30 to a component 4, 6 can be achieved, among other things, using a quick-release clamp, thus ensuring decoupling when the components 4, 6 are replaced. Alternatively, the use of a magnetic adapter for attaching the at least one sound sensor 28, 30 is also possible. Furthermore, at least one sensor, e.g., the electrical sensor 38, is provided for detecting current and voltage values.

[0070] Furthermore, a second positioning of a sensor, e.g., a sound sensor 32, 34, 36, on the welding device 2 and / or a component holder as a component of the welding device 2 is possible. The at least one sensor is not only attached to the components 4, 6 to be joined. It can also be additionally attached to the welding device 2 or, for example, to another component of the welding group. The surface of the component 4, 6, on which the at least one sensor is directly arranged, should be as smooth as possible. Interfaces are kept to a minimum. The attachment is realized, for example, using detachable connection technology, such as screws or a quick-release clamp.

[0071] In a third positioning, it is also possible to attach the at least one sensor, e.g., a structure-borne sound sensor, directly to the torch 16, e.g., the welding torch, and / or the welding arm. In contrast to attachment to the component 4, 6 or another component of the welding device 2, this allows information about the torch 16 as a process device, e.g., a wire movement or a gas flow during the welding and thus joining process, to be obtained. Furthermore, a sensor can be connected to and / or arranged on the robot 20 as a manipulator of the torch 16 and / or the components 4, 6. REFERENCE NUMBERS: 2 welding device 4, 6 component 8 Weld seam 10, 12, 14 clamping device 16 burners 18 Energy source 20 robots 22 Systems 24 Evaluation unit 26 Interface 28, 30, 32, 34, 36 sound sensor 38 Electrical sensor 40 sensors 42 systems 44 Sensor arrangement

Claims

[1] System for monitoring a weld seam (8) formed with a welding device (2) during a welding process on at least one component (4, 6), wherein the system (22, 42) has at least one sound sensor (28, 30, 32, 34, 36), at least one electrical sensor (38) and an evaluation unit (24), wherein the at least one sound sensor (28, 30, 32, 34, 36) is designed to measure values ​​of a structure-borne sound of the at least one component (4, 6), wherein the at least one electrical sensor (38) is designed to measure values ​​of at least one electrical operating parameter during the welding process, wherein the at least one evaluation unit (24) is designed to evaluate the weld seam (8) on the basis of the measured values, wherein the at least one sound sensor (28, 30, 32, 34, 36) is additionally designed to measure values ​​of a structure-borne sound of at least one clamping device (10, 12,14) component of the welding device (2), wherein the at least one clamping device (10, 12, 14) is designed to fix the at least one component (4, 6). [2] System according to claim 1, wherein the at least one electrical sensor (38) is designed to measure values ​​of an electrical current and / or an electrical voltage as the at least one electrical operating parameter. [3] Method for monitoring a weld seam (8) which is formed with a welding device (2) during a welding process on at least one component (4, 6), wherein values ​​of a structure-borne sound of the at least one component (4, 6) are measured by at least one sound sensor (28, 30, 32, 34, 36), wherein values ​​of at least one electrical operating parameter during the welding process are measured by at least one electrical sensor (38), wherein the weld seam (8) is evaluated on the basis of the measured values, wherein values ​​of a structure-borne sound of at least one component of the welding device (2) designed as a clamping device (10, 12, 14) are additionally measured with the at least one sound sensor (28, 30, 32, 34, 36), wherein the at least one clamping device (10, 12, 14) is designed to fix the at least one component (4, 6). [4] Method according to claim 3, wherein values ​​of a frequency and / or amplitude of the structure-borne sound and the at least one electrical operating parameter are measured. [5] Method according to claim 3 or 4, wherein the at least one sound sensor (28, 30, 32, 34, 36) is at least temporarily connected to the at least one component (4, 6). [6] Method according to one of claims 3 to 5, wherein the at least one sound sensor (28, 30, 32, 34, 36) is connected to at least one component of the welding device (2). [7] Method according to one of claims 3 to 6, in which a warning signal is generated if at least one measured value deviates from a target value by a tolerance value.

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