Method for checking a melt and laser welding device

Abstract

The invention relates to a method for testing a melt (10) of two components (2, 3) made of metallic material which are placed against one another and joined by the melt (10) by means of a blasting process, in particular a laser beam process, in which a quality of the melt (10) is detected by directly irradiating a measuring beam (14) by means of a radiation generating device (18) for evaluating the surface (12a) which may have been altered by pore formation,and in which a reflected measuring beam (16) or the scattered light from the surface (12a) of the melt (10) is detected by means of an optical detection device (20) and transmitted to an electronic computing device (22) for evaluation, and by means of the electronic computing device (22), the information of the detected reflected measuring beam (16) or scattered light is compared with a desired state (12b) of a high-quality melt (10) with no or only minimal pore formation. The invention further relates to a laser welding device (1).

Description

The invention relates to a method for checking a melt material according to patent claim 1.DE 10 2020 213 109 A2 discloses a method for monitoring a pore defect of a laser welding process for welding two workpieces made of metallic material by means of a laser beam. In this case, a welding bead is optically monitored per se over the time profile of the solidification, wherein the duration and the time profile of the solidification are monitored, measured / determined and compared with a setpoint value. If the expectation does not agree with the actual value, an indication of a lower quality or problems can be concluded therefrom.It is an object of the invention to provide a possibility by means of which a particularly qualitatively high and reliable laser welding process is made possible.This object is achieved by means of a method having the features of patent claim 1 and by means of a laser welding device according to the invention. Advantageous embodiments of the laser welding device according to the invention are to be regarded as advantageous embodiments of the method according to the invention, wherein the means of the laser welding device are used for carrying out the method steps and vice versa. Further advantageous developments of the invention are described by the dependent patent claims, the following description and by the figure.A first aspect of the invention relates to a method for checking a material to be melted, in particular a bead of two components made of metallic material placed against one another and joined by the material to be melted, by means of a laser beam process. In this method, the quality of the melt material or of the bead is detected by direct irradiation of a measurement beam for evaluating possible changes of the surface due to pore formation.The reflected measurement beams or the scattered light from the surface of the melt material are detected by means of an optical detection device and transmitted to an electronic computing device for evaluation. The electronic computing device compares the information of the detected measurement beam or scattered light with a desired state of a high-quality melt material or a high-quality melt bead with no or only little pore formation.In other words, a method for quality control of welded connections between two metallic components is proposed, which can be present, for example, in the form of hair pins and are connected to one another by a fusible material. The material to be fused can take the form of a bead, for example, without restricting the method to this form. Such a bead is of particular importance and is thus of high quality to produce, since it establishes the electrical connection between the hair pins. The method uses a beam process, in particular a laser beam process, in order to check the melt bead for possible defects. The hair pins, which are electrically connected to one another by the fusible bead, therefore require a reliable electrical connection. The check is carried out by directly irradiating a measurement beam onto the surface of the melt bead in order to identify changes in the surface structure, in particular pore formation. The reflected measurement beams or scattered light from the surface of the bead are thus detected using the optical detector to provide precise data acquisition.The detected signals or information or data are then forwarded or transmitted to an electronic computing device which is responsible for the evaluation. This evaluation comprises the comparison of the information of the detected measurement beam or scattered light with a predefined desired state, which corresponds to a high-quality melt material and has no or only minimal pore formation. This desired state is of great importance in order to ensure that the electrical connection between the hair pins is reliable and does not have any adverse effects. The electronic computing device compares the detected signals with the defined desired state of the material to be melted. The absence of peaks or significant deviations in the detected signal indicates a melt which meets the quality requirements and thus provides a reliable electrical connection between the hair pins.Identifying potential defects or defects in the fused material makes it possible to take measures to improve the welding quality and thus ensure a reliable electrical connection between the hair pins, if necessary.In an advantageous embodiment of the invention, it is provided that the information is defined as measurement signals of a path covered by the measurement beam with respective height differences. This means that the acquired data represent the path of the measurement jet along the surface or within the material to be melted and measure the respective height differences on this distance covered. This enables characterization and evaluation and thus the evaluation of the surface condition.In another advantageous embodiment of the invention, it is provided that optical coherence tomography is used to acquire the information. Optical coherence tomography (OCT) is a non-invasive imaging technique that uses high-resolution cross-sectional images of materials by measuring light back scattering. It is also used, for example, in medicine for the diagnosis of eye and tissue diseases and, as in this case, in material science and quality assurance.In another advantageous embodiment of the invention, it is provided that the information is transmitted wirelessly to an external electronic computing device. This enables flexible data evaluation and data analysis without a physical connection being required, for example a server is provided for this purpose, to which all information is transmitted by means of a data transmission module.In another advantageous embodiment of the invention, it is provided that a new desired state is calculated as a function of the acquired information. It is thus provided that the measured data are evaluated, wherein an updated desired state can also be established. This new desired state takes into account the current conditions and properties of the melt material and the quality standards which can be achieved. By this dynamic adaptation of the desired state, the material to be melted can thus be checked for a common average.In another advantageous embodiment of the invention, it is provided that in the event of deviations between the at least one recording and the desired state, at least one signal is transmitted to an environment by means of the electronic computing device. In this case, it is likewise possible to take account of adjustable tolerance ranges for deviations. In this way, the method may respond to various requirements or variations in the welding process and generate corresponding signals when the detected deviations exceed the predetermined tolerance limits. This allows flexible control and adaptation of the welding process to different conditions in order to maintain the quality of the melt material at a consistent level and at the same time minimize, for example, undesired scrap production.In another advantageous embodiment of the invention, it is provided that by means of the signal, corresponding measures for correcting and / or discharging insufficient melt material are initiated. These measures may include, for example, automated adjustments to the welding process or physical dumping operations to ensure that only high quality molten material remains in the final product.In another advantageous embodiment of the invention, it is provided that a regulation of the machining laser beam is carried out as a function of the signal. In this case, it is provided in particular that the laser beam used for the welding machining is controlled accordingly in order to keep the melt in a liquid state for a longer time and to lengthen the degassing process. This takes place until the detected measurement signal has a homogeneous and stable profile.This adaptive control of the processing laser beam ensures that the material to be melted is kept in an optimum state during the entire welding process, which leads to high-quality and defect-free component connections. In another advantageous embodiment of the invention, it is provided that an optical and / or acoustic and / or tactile warning signal is generated by means of the signal. These warning signals may be communicated to the operator or other systems to indicate irregularities in the welding process and to initiate appropriate steps for error correction.A further aspect of the invention relates to a laser welding device for checking molten material, in particular molten beads between two metallic components which are connected to one another by the welding process. The apparatus comprises a radiation generating device which is designed to generate a measurement beam which can be directed directly onto the surface of the material to be melted in order to detect possible changes in the surface. Furthermore, an optical detection device is present which detects the reflected measurement beam or the scattered light from the surface of the material to be melted. The acquired information of the measurement beam or of the scattered light is forwarded to an electronic computing device which is responsible for the evaluation. This electronic computing device is designed to compare the acquired information with a predefined desired state of a high-quality melt material which has no or only little pore formation. The comparative analysis makes it possible to identify potential defects or defects in the melt material. This ensures that the welded connection between the components meets the quality standards and has the required strength and reliability.The method thus offers a number of advantages. It enables the online assessment of welds and quality testing based on absolute measurements. The quality of the welded connection can thus be monitored in real time. Furthermore, the method allows an active control of the welding process. For example, the melt can be held in a targeted manner in an optimum state, or renewed melting can take place in order to eliminate pores. This contributes to avoiding faulty component connections and thus to reducing rejects in production.The quality of the joint connection is considerably increased, which leads to more reliable end products. This method is used in various welded connections, in particular in laser beam welds and particularly preferably in connections of contacts of an electric motor, such as pin-like copper connections.A further advantage of the method is its adaptability to conventional plant technology. Both scanner welding optics and the measurement system OCT (optical coherence tomography) can be used here. The method is also versatile and is suitable for metal compounds of any type, whether between materials of the same type, such as Cu-Cu or Al-Al, or between mixed compounds, such as Al-Cu.An additional advantage is the potential reduction of the evaluation effort compared to the conventional method of evaluating camera images. This contributes to the efficiency increase of the welding process and enables a more accurate monitoring of the welding quality.Further advantages, features and details of the invention are evident from the following description of preferred exemplary embodiments and on the basis of the drawing(s). The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the invention.The following are shown: FIG. 1 shows a schematic side view of two components joined to one another to illustrate the method for checking a melt material of the two components placed against one another and joined by the melt material; and FIG. 2 shows a diagram of a comparison of an input signal of the melt to be checked with a setpoint value.In the figures, identical and functionally identical elements are provided with the same reference numerals.FIG. 1 shows a schematic side view of two components 2, 3 joined together by a laser welding device 1 to illustrate a method for checking a fused material 10 of the two components 2, 3 made of metallic material which are placed against one another and joined together by the fused material 10 and which have / are joined together within the scope of a laser beam process. The laser welding device 1 comprises a radiation generating device 18 for generating a measurement beam 14, which can be aligned precisely on the surface 12 aof the melt 10. In this case, the alignment of the measurement beam 14 takes place in order to detect possible surface changes which could be caused by pore formation.An optical detection device 20 is arranged to detect the reflected measurement beam 16 or the scattered light from the surface 12 aof the melt 10. The acquired information is transmitted or forwarded in the form of measurement signals to an electronic computing device 22, which is responsible for the evaluation. The electronic computing device 22 has specialized algorithms and analysis functions in particular in order to compare the detected measurement signals with a clearly defined desired state 12 b, which stands for a high-quality melt product 10 with no or only minimal pore formation. This comparison makes it possible to evaluate the quality of the melt material 10 and, if appropriate, to initiate measures for improving the welded connection.The method for checking the material to be melted 10 is thus carried out by the direct irradiation of the measurement beam 14 with the aid of the radiation generating device 18 for evaluating possible surface changes on account of pore formation. The optical detection device 20 detects the reflected measurement beam 16 or the scattered light from the surface 12 aof the melt material 10 and passes the data on to the electronic computing device 22 for evaluation. The electronic computing device 22 performs the comparison of the acquired information with the desired state 12 bof a high-quality melt material 10 with no or only little pore formation.The schematic side view thus shows two joined components 2, 3 in order to illustrate the method for checking a melt 10. The material to be melted 10 serves for connecting the two components 2, 3 and is checked for its quality during the laser beam process.FIG. 2 shows a diagram with a comparison of an input signal of the melt material 10 to be checked with a setpoint value. Thus, a diagram is shown which shows a comparison between an input signal originating from the melting material 10 to be checked and a desired value. The diagram comprises two main signals, namely the actual measurement signal 24 aof the melt material 10 and the desired measurement signal 24 b.The Y axis denoted by the reference symbol A represents the height of the measurement signals 24 a, 24 b, wherein the respective measurement values are represented on this axis. The X-axis denoted by the reference symbol B represents the course of the surface 12 aand represents the path which the measurement signals travel along the surface 12 a. The actual measurement signal 24 acorresponds to the actually measured data of the material to be fused 10, while the target measurement signal 24 brepresents the ideal target value which is expected for a high-quality material to be fused 10 with minimal formation of pores.By comparing these two measurement signals 24 a, 24 b, deviations between the measured actual value and the desired setpoint value can be determined, whereby the quality of the melt material 10 can be evaluated. This diagram enables a visual representation and analysis of the differences between the actual state and the desired target state of the melt material 10, whereby possible adaptations in the welding process can be carried out in order in particular to optimize the quality.The measurement signal 24 ain this case shows a signal which is unstable over time and has irregularities, these irregularities being attributable to fluctuations which arise as a result of degassing pores in the material to be melted 10. This indicates an inferior quality, since the surface is inhomogeneous.In contrast, the measurement signal 24 bshows a homogeneous surface, in which only slight fluctuations occur in the melting material 10. This indicates good quality, since the melting material 10 is uniform and stable.In other words, the actual measurement signal 24 aexperiments due to fluctuations which indicate pore degassing in the melt and indicate inferior quality, while the measurement signal 24 bindicates a homogeneous surface and thus good quality.In summary, the invention proposes a method for quality assurance on component connections.List of reference characters1 Laser welding apparatus 2 Component 3 Component 10 Material to be fused 12 aSurface 12 b Soll state 14 Measuring beam 16 Measuring beam 18 Radiation generating device 20 Detection device 22 Computing device 24 aActual measurement signal 24 b Soll measurement signal A Y-axis B X-axisReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2020 213 109 A2

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Claims

Method for checking a material to be fused (10) of two components (2, 3) made of metallic material placed against one another and joined by the material to be fused (10) by means of a laser beam process, in which a quality of the material to be fused (10) is detected by direct irradiation of a measurement beam (14) by means of a radiation generating device (18) for evaluating the surface (12a) possibly changed by pore formation, and in which a reflected measurement beam (16) or the scattered light from the surface (12a) of the material to be fused (10) is detected by means of an optical detecting device (20) and transmitted to an electronic computing device (22) for evaluation, and the information of the detected reflected measurement beam (16) or scattered light is compared by means of the electronic computing device (22) with a setpoint state (12b) of a high-quality material to be fused (10) with no or only little pore formation.Method according to Claim 1, characterized in that the information is defined as measurement signals of a path travelled by the measurement beam with respective height differences.Method according to claim 1 or 2, characterised in that optical coherence tomography is used to acquire the information.Method according to one of the preceding claims, characterized in that the information is transmitted wirelessly to an external electronic computing device.Method according to one of the preceding claims, characterized in that a new sol state is calculated as a function of the acquired information.Method according to one of the preceding claims, characterized in that, in the event of deviations between the at least one recording and the desired state, at least one signal is transmitted to an environment by means of the electronic computing device.Method according to one of the preceding claims, characterized in that corresponding measures for correcting and / or discharging inadequate melt material are initiated by means of the signal.Method according to claim 7, characterised in that a regulation of the machining laser beam is carried out as a function of the signal.Method according to claim 7 or 8, characterised in that an optical and / or acoustic and / or tactile warning signal is generated by means of the signal.Laser welding device (1) for checking fused material (10) of two components (2, 3) made of metallic material placed against one another and joined by the fused material (10) by means of a beam process, in particular a laser beam process, having a radiation generating device (18) for generating a measurement beam (14) which can be aligned directly on a surface (12a) of the fused material (10) for detecting possible changes of the surface (12a), having an optical detecting device (20) for detecting a reflected measurement beam (16) or the scattered light from the surface (12a) of the fused material (10), having an electronic computing device (22) for evaluating the detected information of the reflected measurement beam (16) or scattered light which is designed for this purpose, comparing the recorded information and a desired state (12b) of a high-quality melt material (10) with no or only little pore formation.

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