ROBOTIC WELDING SYSTEM AND METHOD FOR OPERATING A ROBOTIC WELDING SYSTEM - Patent application

Abstract

The invention provides a robotic welding system (100) and a method for operating the robotic welding system. The robotic welding system (100) comprises: a welding torch (110) having a consumable electrode (112); a robot (120) configured to guide a welding torch (110); a sensor unit (131) configured to implement a scanning program by the robot (120) and the welding torch (110), wherein the geometry of at least one workpiece (1, 2) is scanned and detected by the consumable electrode (11), at least one position and / or orientation of the robot (120) is simultaneously detected, and a cycle of advancing and retracting the electrode tip (111) of the consumable electrode (112) is periodically repeated to detect the geometry of the at least one workpiece (1, 2); and and an arithmetic unit (132) configured to acquire specifications of a welding task to be performed on at least one workpiece (1, 2) and generate, based on the acquired specifications and the results of the scanning program, an output signal designed to generate or set at least one parameter of the welding task to be performed.

Description

[Technical Field]

[0001] The present invention relates to a robotic welding system having a robot that guides a welding torch with a consumable electrode, and a method for operating a robotic welding system having such a robot. [Background technology]

[0002] Robotic welding systems are used to process one or more workpieces in a welding process. Even when many requirements assume that the basic shape of the workpieces is known, it can still happen that an individual workpiece, or the arrangement of two or more workpieces relative to one another, does not meet expected specifications. In robotic welding systems, which are particularly advantageous when welding processes are automated at high speeds, such situations can lead to delays or results that do not meet quality requirements.

[0003] It is known, for example from EP 1 233 845 B1, that the coordinates of the weld center can be determined by traversing a workpiece or workpieces with a welding wire and simultaneously monitoring the occurrence of short circuits.

[0004] A need also exists for improved robotic welding systems and methods for operating such robotic welding systems that are capable of detecting unexpected or problematic characteristics of a welding task and, ideally, automatically correcting them wherever possible, a welding task being understood as, among other things, the arrangement of at least one workpiece to be welded, the alignment of multiple workpieces, their quality characteristics, etc., and the welding process to be performed on this arrangement with all associated parameters and characteristics. Summary of the Invention

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved robotic welding system and a corresponding method for controlling such a robotic welding system that overcomes the above-mentioned problems.

[0006] Therefore, according to a first aspect of the present invention, a welding torch (or welding rod) with a consumable electrode; a robot configured to guide a welding torch; a sensor unit configured to execute, by the robot and the welding torch, a scanning program for at least partially scanning and detecting the geometry of at least one workpiece by a consumable electrode of the welding torch, wherein at least one position and / or orientation of the robot is detected simultaneously; and a computing unit configured to obtain specifications of a welding task to be performed on at least one workpiece and to generate an output signal designed to generate at least one parameter of the welding task to be performed based on the obtained specifications and the results of the scanning program; A robotic welding system is provided, including:

[0007] In particular, the welding power supply can be designed to establish a voltage between a consumable electrode and a second electrode that can be connected to at least one workpiece. The sensor unit can be configured to detect the geometry of at least one workpiece in a cycle that includes advancing and retracting an electrode tip of a consumable wire electrode.

[0008] In particular, the cyclically repeated cycle advancing the electrode tip of the consumable electrode until a short circuit between the consumable electrode and the at least one workpiece is detected via a second electrode, which is connected to the at least one workpiece; storing the position of the consumable electrode at the time the short circuit was detected; and Retract the electrode tip until the short circuit is eliminated. may be shown. The geometry of each workpiece may include the internal and / or external geometric properties of the workpiece. Internal geometric properties may include, for example, its dimensions, its outer shape, etc. External geometric properties of the workpiece may include, for example, its position and / or location in three-dimensional space relative to a fixed coordinate system, such as that typically used by a welding robot.

[0009] Generating a parameter means generating information or a signal associated with or assigned to a welding task, such as, for example, generating a warning signal, entering information in a data field, generating a digital flag in a digital report regarding the performance of the welding task ("flagmenting"). Setting a parameter can be understood as initially setting a parameter (or parameter value), changing or adjusting a parameter (or parameter value), or selecting an option from a list. The parameters of the welding task to be performed can also be a welding process type, for example, automatically selected from a list of welding process types. For example, detecting the geometry of two workpieces can reveal that a gap exists between the workpieces, and based on this, a suitable welding process type can be selected, for example, a pulse process, a cold metal transfer (CMT) process, etc. All parameters for the selected welding process type can then be automatically set or suggested to the user.

[0010] The robot may in particular be a robot arm or a larger robot unit that may in particular have a robot arm for guiding a welding torch. The position and / or orientation of the robot is understood to relate in particular to the part of the robot that guides the welding torch. In the case of an articulated robot arm, the orientation may include, for example, multiple angles in the coordinate system of each joint.

[0011] When referring to "units" in this specification, it is understood that this does not necessarily mean that such units are implemented as separate units distinct from one another. When such units are implemented as software, they may be implemented as program code sections or components that may be distinct from one another but may also be intertwined. Similarly, when one or more units are implemented as hardware, the functionality of one or more units may be implemented by a single hardware component.

[0012] Alternatively or additionally, different functions of a single unit, or even different functions of different units, may be realized on one or more separate hardware components, and thus do not necessarily have a one-to-one relationship with the units. In this sense, any device, system, method, etc. having all the features and functionality attributed to a particular unit may be understood to have, represent, or implement such a unit. In particular, all units may be realized as program code executed on a computing device, for example, by a server or cloud computing platform.

[0013] The entire robotic welding system can also be located locally, for example the sensor unit and / or the computing unit can be integrated into the robot and / or into the welding power source of the robotic welding system.

[0014] The invention further provides a method for operating a robotic welding system having a robot guiding a welding torch having a consumable electrode, the method comprising: executing a scanning program by the robot and the welding torch, wherein the geometry of at least one workpiece is at least partially scanned and detected by a consumable electrode of the welding torch, and at least one position and / or orientation of the robot is simultaneously detected; obtaining a specification of a welding task to be performed on at least one workpiece; The method includes generating an output signal based on the received specifications and the results of the scanning program, the output signal being designed to generate, set, or modify at least one parameter of the welding task to be performed.

[0015] The method may further include connecting a second electrode to the at least one workpiece and establishing a voltage between the consumable electrode and the second electrode. Advantageously, a cycle involving advancing and retracting the electrode tip of the consumable electrode is repeated periodically to ascertain the geometry of at least one workpiece.

[0016] The periodically repeating cycle is, in particular, advancing the electrode tip of the consumable electrode until a short circuit between the consumable electrode and the at least one workpiece is detected via a second electrode, which is connected to the at least one workpiece; storing the position of the consumable electrode at the time the short circuit was detected; and Retract the electrode tip until the short circuit is eliminated. may include: According to some advantageous embodiments, further developments or variants, the robotic welding system further comprises a welding power source. The output signal may be designed to set target, minimum and / or maximum values ​​for the parameters of the welding power source for performing the welding task to be performed. It is also possible to set (e.g., set for the first time or change) an entire parameter set consisting of several parameters.

[0017] The parameters may be, for example, electrical or non-electrical parameters. The parameters may be parameters of the welding power source, the robot, or other parts or elements of the welding system or procedure or process. The electrical parameters may be welding current, welding voltage, welding power, and / or others. The non-electrical parameters may include, for example, gas flow rate, gas pre-flow and post-flow time, wire retract length, wire feed speed, and / or others. Other parameters are known to those skilled in the art.

[0018] According to some advantageous embodiments, further developments, or variants, the output signal can be designed to set a target, minimum, and / or maximum value for the welding speed of the robot when performing the welding task to be performed. For example, the depth and / or width of the gap to be welded can in turn be determined as part of the scanning program, which can then infer the required amount of filler welding material or the A dimension (for fillet welds) from the consumable electrode (or welding wire electrode). This allows for the calculation of an optimal welding speed, especially in combination with knowledge of the electrical parameters of the welding power source and, optionally, the characteristics of the electrode, i.e., the welding wire to be melted. In a robotic welding system, this welding speed can then be set accordingly by the output signal, thereby controlling the robot to control the welding torch at this calculated optimal welding speed while performing the welding task.

[0019] According to some advantageous embodiments, further developments, and variants, the output signal is designed to set a target, minimum, and / or maximum value for the angle of attack of the robot when performing the welding task to be performed. This can be used to control the robot to adopt a corresponding angle of attack via the output signal and / or, depending on requirements, to perform the welding task to be performed permanently or at least partially at the set angle of attack. As already mentioned, for example, the geometry of a fillet weld or a butt joint can be determined as part of the scanning program, and based on this, the optimal angle of attack for the welding task to be performed can be calculated using a computing unit. The angle of attack can also be a temporal sequence of the angle of attack, i.e., the angle of attack as a function of time during the execution of the welding task, especially if the optimal angle of attack changes one or more times during the welding task to be performed.

[0020] According to some preferred embodiments, embodiment variants, or further developments, the output signal is designed to adjust, in particular change, the welding position and / or welding path of the robot in order to perform the welding task to be performed. This can be advantageous, for example, when using the scanned geometry of at least one workpiece to determine that the workpiece is not in the desired position, e.g., not in the position used to teach the robot's movements. The robot can have a correction program that only needs to be informed of the actual position of the workpiece, for example, in the form of explicit coordinates of the actual position and / or information regarding the deviation between the current position (actual position) and an expected, previously determined or preset position (target position). The correction program then automatically adjusts the learned welding position and / or welding path accordingly.

[0021] The presence of a workpiece in an incorrect position and / or alignment may be due, for example, to signs of wear in the holding device for the at least one workpiece, deviations in the shape of the at least one workpiece itself, and / or batch tolerances. In an automated welding cell, the geometry of the workpiece, in particular its positioning and / or alignment in space, may be recorded, for example, before each welding task, before or after each workpiece, after a predetermined number of welding tasks or workpieces, or at regular intervals (e.g., once a day).

[0022] According to some advantageous embodiments, further developments, or variations, the specification of the welding task to be performed includes at least one requirement. The computing unit may be designed to determine whether the at least one requirement is met based on the results of the scanning program. As explained below, the results of whether the at least one requirement is met or which and / or how many of a plurality of requirements are met can be used in various ways to usefully control the robotic welding system. Determining whether a requirement is met may include, first, determining that the requirement is definitely met, and / or, second, determining that the requirement can be met but requires permissible parameter changes to the robotic welding system, and / or, third, determining that the requirement is not feasible under any circumstances because there are no possible or permissible parameter changes that would make the requirement feasible.

[0023] Modifiable (or customizable) parameters of a robotic welding system include, for example: Welding power source parameters (current, voltage, power, gas flow, etc.); - Welding speed and / or acceleration of the robot; Robot angle of attack; Welding position and / or welding path and / or other may include:

[0024] The lack of approval of a parameter change that is actually possible for the robotic welding system may be due, for example, to a corresponding lack of approval by a current user of the robotic welding system, or the robotic welding system not currently being enabled to change the required parameters. The robotic welding system may include a user interface that allows a user to enable one or more functions, for example, functions required to change the parameters for performing a welding task, particularly for payment.

[0025] According to some advantageous embodiments, further developments, or variants, the robot welding system is configured such that, if the computing unit reaches the conclusion that at least one requirement cannot be fulfilled, an output signal is generated to move the controllable holding device for the robot and / or at least one of the at least one workpiece so that the requirement is fulfilled as far as possible or completely. In other words, an output signal can be generated so that possible changes that allow the at least one requirement to be fulfilled are automatically implemented, or at least changes that result in the requirement being fulfilled as best as possible. For each requirement, it can be specified individually whether the requirement must be fulfilled 100 percent, or whether partial fulfillment of the requirement is also acceptable.

[0026] The robotic welding system can be configured to automatically perform a welding task only if at least one requirement is fully or at least sufficiently met. If multiple welding tasks are provided and one of them cannot be performed, only the welding task whose requirements are fully (or, in a variant, at least fully) met can be performed. Alternatives can also be provided, i.e., if welding task A could in principle be provided but cannot be performed because its requirements are not fully or sufficiently met, welding task B should be performed instead. Welding task B may, for example, involve a different type of welding process, a different type of seam, and / or the like.

[0027] According to some advantageous embodiments, further developments, or variations, the welding task includes at least two workpieces. At least one requirement may include a relative alignment between the at least two workpieces. For example, the requirement may include a maximum gap width between two plate-shaped workpieces at a butt joint, a maximum angle between the two workpieces, and / or others. The requirement may be a yes / no requirement, i.e., either met or not, a more-is-better requirement, or a combination thereof. For example, a yes / no requirement may require that the gap at the butt joint be at most x mm. A more-is-better requirement may specify that the gap should be as small as possible. A combined requirement may specify that the gap should be as small as possible, but no larger than x mm. Thus, an output signal may be generated to control a robot and / or a controllable holding device for at least one of the at least two workpieces to ensure that the requirement is met.

[0028] According to some advantageous embodiments, further developments, or variants, the output signal is designed to generate, as a parameter of the welding task to be performed, information about the expected quality of the result of the performed welding task. The expected quality can be based, for example, on the geometric dimensions of at least one workpiece or the relative positioning of at least two workpieces relative to one another, which can be known based on the scanning program of the computing unit. The calculation of the information about the expected quality can also include further information known to the computing unit, such as information about the capabilities of the robotic welding system, in particular the welding torch, information about properties of at least one workpiece, such as material properties, information about the time available for the welding task to be performed, and / or the like.

[0029] According to some advantageous embodiments, further developments, or variants, the at least one requirement includes a requirement for an expected quality of the performed welding task. The output signal can be designed to indicate that the welding task for at least one workpiece should be stopped if the expected quality does not match a predetermined minimum quality. In this way, it is possible to avoid wasting valuable time and resources of the robotic welding system on inferior products. Preferably, the expected quality of the performed welding task is calculated after all possible parameter changes have been adjusted to maximally satisfy all existing requirements for the welding task.

[0030] According to some advantageous embodiments, further developments, or variants, the at least one requirement includes a requirement for a geometric characteristic possessed by at least one of the at least one workpiece. The output signal can be designed to indicate the end of the welding task for the at least one workpiece if the geometric characteristic is not present. The geometric characteristic of the at least one workpiece can be determined specifically by the scanning program. In this way, time-consuming and / or costly pre-inspection of the workpieces to be welded can be omitted and instead can be performed automatically by the robotic welding system as part of the scanning program. The geometric characteristic to be met can be, for example, a desired minimum or maximum thickness of the plate-shaped workpiece (sheet metal).

[0031] According to some preferred embodiments, embodiment variations or refinements, the cycle is repeated at a frequency of 10 Hz to 500 Hz, preferably 30 Hz to 300 Hz, particularly preferably 75 Hz to 125 Hz. According to some preferred embodiments, embodiment variations or refinements, the sensor unit is adapted to receive robot information signals in addition to position signals associated with the positions of the electrode tips, which may for example indicate the respective position and / or orientation of the robots. The sensor unit can be configured to provide a timestamp for all position and / or information signals (or at least for position and / or information signals that do not have their own timestamp), so that a relationship is established via a common timestamp between, on the one hand, the position and orientation of the robot in its time and coordinate system and, on the other hand, the stored position of the electrode tip of the wire electrode. Advantageously, the robot moves along a scan path to scan the at least one workpiece independently of the cycle of the wire electrode.

[0032] According to some advantageous embodiments, further developments or variations, the method further comprises performing, by the robot and the welding torch, a welding task comprising at least one generated, set or modified parameter. The output signal can be designed to automatically select a suitable welding process type from a list of welding process types, and the selected welding process type can be used to perform the welding task. Further information that may represent the parameters of the welding task may include, for example, information about what parameter changes have been made to ensure that at least one requirement of the specification of the welding task to be performed can be met and / or the like.

[0033] According to a further aspect, the invention provides a computer program product comprising executable program code adapted to perform the method of an embodiment of the invention when executed. According to a further aspect, the invention provides a non-transitory computer-readable data storage medium comprising executable program code adapted, when executed, to perform the method of an embodiment of the invention. The data storage medium may be, for example, a hard disk, a solid-state storage device, a CD, a DVD, a memory card, etc. According to a further aspect, the invention provides a data stream or data structure containing or adapted to generate executable program code, the executable program code being adapted to perform the method of an embodiment of the invention when executed. Further preferred embodiments, embodiment variants and further embodiments are set out in the dependent claims and in the description with reference to the drawings.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained in more detail with reference to example embodiments shown in the figures of the drawing, in which: [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is a schematic diagram of a robot welding system according to a first embodiment of the present invention. [Figure 2] Figure 2a) is an exemplary diagram of the execution of the scanning program. Figure 2b) is the first result of the scanning program from Figure 2a). [Figure 3] Figure 3a) is an exemplary illustration of a further execution of the scanning program, and Figure 3b) is the first result of the scanning program from Figure 3a). [Figure 4] Figures 4a) to 4f) are various graphs to illustrate possible signal processing and uses of the results of the scanning program. [Figure 5] 5a) to 5n) are schematic diagrams illustrating possible welding situations or problems associated with the geometry or characteristics of the workpiece. [Figure 6] 6a)-6i) are schematic diagrams illustrating other possible welding situations or problems associated with the geometry or characteristics of the workpiece. [Figure 7] FIG. 7 is a schematic flow chart illustrating a method according to a further embodiment of the present invention. [Figure 8] FIG. 8 is a schematic block diagram illustrating a computer program product according to another embodiment of the present invention. [Figure 9] FIG. 9 is a schematic block diagram illustrating a data storage medium according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] Detailed Description of the Drawings In all figures, identical or functionally identical elements and devices have been given the same reference numerals unless otherwise indicated. The names and numbering of the method steps do not necessarily imply a sequence, but are intended to provide better clarity and distinction, although in some variations the sequence may correspond to the numbering sequence.

[0037] 1 shows a schematic diagram of a robotic welding system 100 according to a first embodiment of the present invention. The robotic welding system 100 includes a welding torch 110 that guides a consumable wire electrode 112 (i.e., a welding wire) that is in turn guided by a robot 120, particularly a robot arm 121, of the robotic welding system 100. A welding power source 140 of the robotic welding system 100 is designed to establish a voltage between the consumable wire electrode 112 and a second electrode 113 that can be connected to workpieces 1, 2.

[0038] One or more holding devices 150, one or more of which in turn are controllable, may be provided for holding and / or positioning at least one of the workpieces 1, 2. Such holding devices 150 may be part of the robotic welding system 100 and advantageously be controlled by the latter. The holding device 150 may, for example, be another robot, for example a robotic arm.

[0039] The robotic welding system 100 is designed and configured to execute a scanning program by the robot 120 and the welding torch 110, and also includes a sensor unit 131 by which the geometry of at least one workpiece 1, 2 is at least partially scanned and detected by the consumable wire electrode 112 of the welding torch 110. At the same time, at least one position and / or orientation of the robot 120 is detected, for example, by an information signal 73 of the robot 120. In combination, it is possible to determine, for example, the geometric characteristics (length, height, size, shape) and relative positioning of multiple workpieces 1, 2 with respect to one another.

[0040] In the situation shown in FIG. 1, the sensor unit 131 is integrated into the welding power source 140 as an example, but other arrangements are also possible, such as integration into the robot 120, being located in a separate housing, and / or having the sensor unit 131 located remotely (e.g., implemented by a remotely located server, cloud computing platform, etc.).

[0041] To implement the scanning program, the sensor unit 131 can specifically comprise the wire feeder 141 of the robotic welding system 100, or the wire feeder 141 and the sensor unit 131 can be configured such that the sensor unit can control the wire feeder 141 to specifically implement the scanning program. For this purpose, the sensor unit 131 can send a control signal 71 to the wire feeder 141. In the variant shown, the wire feeder 141 is part of the welding power source 140. Alternative embodiments are known to those skilled in the art and will not be discussed in more detail here.

[0042] The sensor unit 131 may also have a voltage measuring device (among other things) for short circuit detection or may be configured to receive and evaluate the detection signal 72 from a voltage measuring device 142 of the welding power source 140 (as shown in FIG. 1).

[0043] To carry out the scanning program, the sensor unit 131 can, based on the detection signal 72 of the voltage measuring device 142, instruct the wire feed device 141 to advance the consumable wire electrode 112 at a predetermined speed until it detects (via another electrode 113) a short circuit between the consumable wire electrode 112 and the workpiece 1. The electrical connection 3 between the workpieces 1, 2 (usually provided by a clamping or holding device) ensures that a short circuit between the consumable wire electrode 112 and both workpieces 1, 2 can be detected.

[0044] The corresponding position of the wire electrode 112 when a short circuit occurs ("initial position") can be measured and stored, for example, by the motor encoder and / or sensor unit 131 of the wire feeder 141. The initially determined position of the workpiece 1 can be defined as a reference distance, for example, a zero line. The electrode tip of the wire electrode 112 is then retracted until the short circuit is eliminated, and the cycle of advancement, position storage, and retraction is repeated periodically, for example, at a frequency of 10 Hz to 500 Hz, preferably 30 Hz to 300 Hz, particularly preferably 75 Hz to 125 Hz. Each time a short circuit occurs, the position information of the welding wire is stored.

[0045] In addition to the position of the electrode tip, the sensor unit 131 also receives the information signal 73 of the robot 120. All signals converging on the sensor unit 131 can be time-stamped by the sensor unit 131, so that a relationship is established between the position and orientation of the robot 120 in its time and coordinate system on the one hand and the stored position of the electrode tip of the wire electrode 112 on the other hand via a common time-stamp.

[0046] Alternatively, the robot's position signals and / or information signals 73 can be provided with their own timestamps, whereby the sensor unit 131 provides timestamps only to signals that do not have their own timestamps, calculates a one-to-one correlation between the / all received timestamps and / or self-generated timestamps, and uses them in a later process for temporal correlation between the electrode tip position and the position and orientation of the robot 120. A variant in which the sensor unit 131 provides timestamps to all signals is described in more detail below, but the invention is not intended to be limited thereto. However, the expression "common timestamp" is always intended to mean correlating signals and timestamps using one of the above (or other known) methods to obtain signals or positions and orientations that are correlated with each other in time.

[0047] Thus, the robot 120 can be instructed (e.g., by the sensor unit 131 or another element of the robotic welding system 100) to move the wire electrode 112 along a scan path in a direction perpendicular to the wire feed direction as part of the scanning process. Because the data is linked via a common timestamp, the normally significantly slower movements of the robot 120 can occur independently of the back and forth cycle of the wire electrode 112.

[0048] Figures 2a) to 3b) illustrate this procedure. In both Figures 2a) and 3a), welding torch 110 (more precisely, the tip of the contact tube of welding torch 110) is shown both at a first time t1 and at a later time t2. At time t1, electrode tip 111 of consumable wire electrode 112 contacts first workpiece 1, which will be welded to second workpiece 2 with a bead seam according to the welding task of Figure 2a) and with a fillet weld according to the welding task of Figure 3a). 2b) and 3b) show the feed path D of the electrode tip 111 as a function of time t in seconds from a start position at time t1 to an end position of the scanning program at time t2. The welding torch 110 is moved by the robot 120 along a scanning trajectory T, which preferably extends perpendicular to the weld seam to be made (in the drawing plane in FIGS. 2a) and 3a). The scanning trajectory T is preferably linear in space. For some welding tasks, such as that of FIG. 2a), it is advantageous if the scanning trajectory T also extends at least partially parallel to at least one surface of at least one workpiece 1, 2. 2b) and 3b) already show schematically how comprehensive geometric information can thus be generated regarding the geometrical properties of both workpieces 1, 2 and their arrangement relative to one another.

[0049] Figures 4a-f explain in more detail the further processing using the welding task in Figures 2a and 2b. The association or correlation of the various signals via a common horizontal axis and a common timestamp can be clearly seen. FIG. 4a) shows a raw signal generated according to the procedure described in FIGS. 2a) to 3b). FIG. 4b) shows a filtered (smoothed) signal based on this. FIG. 4c) shows how the actual geometry of the welding situation (i.e., workpieces 1, 2 and their arrangement) can be extracted from the signal of FIG. 4b). For this purpose, the sensor unit 131 may have information about the welding task, e.g., about which welding situations should be present in the welding task and / or what type of weld seam should be produced. Thus, depending on the welding task and / or the weld seam, the sensor unit 131 may have an ideal parameterization of the curve as shown in FIG. 4c), for which the signal of FIG. 4b) is analyzed and processed by mathematical methods, e.g., filtering and / or fitting, to determine the current shape and configuration of the workpiece. Fig. 4d) shows the position of the robot 120 as a function of time in X, Y and Z coordinates of a predefined coordinate system which can be connected to the robot 120 in a fixed position, for example. Fig. 4e) accordingly shows the orientation of the robot 120 in three angles: alpha, beta and gamma. This information can be provided to the sensor unit 131 via an information signal 73 from the robot 120 to the sensor unit 131. Alternatively, the sensor unit 131 can be configured to send control signals 74 to the robot 120 for movement of the robot 120. In this case, the control signals 74 can be used to detect the position, orientation etc. of the robot 120. Fig. 4f) shows the tool center velocity of the robot 120.

[0050] 1, the robotic welding system 100 further includes a computing unit 132 arranged to obtain specifications of a welding task to be performed on at least one workpiece 1, 2, and to generate, based on the obtained specifications and the results of the scanning program, an output signal 75 designed to generate or set at least one parameter of the welding task to be performed. Depending on which parameter is generated or set, the output signal 75 can be sent to various elements, such as the robot 120, the power electronics 143 of the welding power source 140, one or more holding devices 150, and / or others.

[0051] The parameter or parameters may in particular be parameters of the welding power source 140 (current, voltage, power), the welding speed and / or acceleration of the robot 120, one or more angles of attack of the robot 120, the welding position or welding path, the welding process type and / or others, as well as respective minimum, maximum, target values, etc., as already explained above.

[0052] The number and type of parameter changes will vary depending on the welding task and the detected geometry. For example, the computing unit 132 may have information that the welding task includes a fillet weld welding process with a molten wire electrode 112. The geometry of the welding situation detected by the scanning program may include, for example, the angle between the workpieces 1, 2, which may require an adjustment to the angle of attack of the robot 120.

[0053] Similarly, the scanning program can detect the gap width of the butt joint, and based on this, calculate the required amount of molten material for the molten wire electrode 112, and based on this, the welding speed (or the movement speed of the robot 120 along the weld seam), welding current (the electrical output current of the welding power source), welding position, welding path, welding process type, etc. can be set (e.g., adjusted).

[0054] The computing unit 132 may also have information about all the parameters that can be changed and the requirements for the welding task. For example, in the case of a fillet weld as in Figure 3a), it may be specified that the angle between the workpieces 1, 2 is ideally 90°.

[0055] If the sensor unit 131 determines, for example, via a scanning program, that the angle is currently 80°, then various possibilities exist. If the computing unit 132 has access to a controllable holding device 150 for at least one of the workpieces 1, 2, whose angle can be changed by the controllable holding device 150, the computing unit 132 can control this controllable holding device 150 via the output signal 75 to set the angle as close to 90° as possible. If the welding task involves an angle tolerance, for example allowing a deviation of + / - 5°, then the holding device 150 can be controlled to change the angle to at least 85°-95°, so that the set angle is as close to 90° as possible.

[0056] In other cases, the welding task may include further requirements and / or information regarding the quality of the welding task to be performed, for example, specifying that an angle between 89° and 91° allows the welding task to be performed with high quality, an angle between 85° and 95° allows the welding task to be performed with reduced quality, and any other angle does not provide acceptable quality.

[0057] In this case, the computing unit 132 may first control the holding device 150 to generate an angle as close as possible to 90°. If the result is precisely known, it can continue; if not, the computing unit 132 can instruct the sensor unit 131 to perform a further scanning program to record the result of controlling the holding device 150. If necessary, this can be done multiple times until no further improvement is possible. Based on the finally set angle, it can then be determined whether the welding task can be performed with high quality, reduced quality, or unacceptable quality, and whether it is still advisable to perform the welding task. This means that the welding task can be stopped if acceptable quality cannot be achieved.

[0058] The welding task may include or provide a data structure such that a report regarding the performed welding task is generated by the robotic welding system 100. This report may include information regarding the final quality of the performed welding task (or, in other words, the completed welded workpiece).

[0059] 5 and 6 illustrate various possible weld conditions, how a scanning program can detect them, and what conclusions can be drawn from them. The weld conditions shown are not necessarily defective, but may be desired in this form by, for example, requiring a particular gap width, a particular offset between the two workpieces, etc. If the desired weld condition is present, a parameter can be generated that indicates this is the case, for example, for downstream quality control purposes. If the current situation is undesirable (e.g., there is a gap, offset, angle, etc. that should not exist, or vice versa), the parameters of the welding task can be set appropriately, as described above and below, to improve the results of the welding task. Figures 5a-5d show welding tasks involving fillet welds, where one workpiece may be misaligned relative to the other (Figure 5a), a vertical workpiece may not be flush with a horizontal workpiece (Figures 5b and 5c), or a gap may exist between the workpieces (Figure 5d). Figures 5e)-5g) show welding tasks involving flange seams, where there may be a gap (Figure 5e), Figure 5g)) or a height offset (Figure 5f)) between the two workpieces. Figures 5h-5k show welding tasks involving overlapping seams. In this case, there may be horizontal misalignment (Figure 5h), one of the workpieces may be deteriorated, e.g., its edge may be dirty (Figure 5i), there may be a gap and / or a non-zero angle between the workpieces (Figure 5j), or there may be a bevel in front of the weld edge (Figure 5k). Similar welding situations can also occur in the joining of three sheets, with each case occurring between two adjacent sheets (workpieces). In some variations, for degraded workpieces detected by the scanning program, the welding task may not be performed (i.e., aborted) on this or these particular workpieces due to corresponding requirements contained in the welding task specifications, or the welding task may still be performed, whereby the condition of the workpiece and / or the quality of the final welded workpiece are recorded in a report on the performed welding task. Figures 5l)-5n) show welding tasks involving V-seams with or without a gap, where the workpieces can face each other without a gap (Figure 5l) or separated by a gap (Figure 5n), or there can be a height offset (Figure 5m) or an angular offset (not shown) between the two workpieces.

[0060] Figures 6a-6c show welding tasks involving Y-seams, where the cutout can be symmetrical (Figure 6a), the workpieces can be offset (Figure 6b), or there can be a gap between the workpieces (Figure 6c). Figures 6d-6f show a welding task involving a round bar against a metal sheet. In this case, the round bar may rest on the metal sheet (Figure 6d) or there may be a gap between the round bar and the metal sheet (Figure 6e). However, the scanning program may also determine that one of the workpieces, the round bar, has incorrect geometric characteristics, such as an incorrect radius or deviation from circularity (Figure 6f). 6g-6i) illustrate a welding task involving butt welding, where the workpieces can be positioned flush with one another (FIG. 6g) or spaced apart by a gap (FIG. 6i). The geometric characteristics of the chamfer at the workpiece end can also be detected (FIG. 6h), and thus whether it has undesirable characteristics (e.g., wrong size, wrong angle, etc.).

[0061] FIG. 7 shows a schematic flow chart illustrating a method according to one embodiment of the present invention, namely, a method for operating a robotic welding system including a robot guiding a welding torch with a consumable electrode. In step S10, a scanning program is performed by the robot 120 and the welding torch 110, in which the geometry of at least one workpiece 1, 2 is at least partially scanned and detected by the consumable wire electrode 112 of the welding torch 110, thereby simultaneously detecting at least one position and / or orientation of the robot 120. This can be done, for example, as described in detail above, in particular with reference to Figures 1-6.

[0062] In particular, the following steps may be performed as part of the scanning program, particularly in numerical order: In step S11, the welding torch 110 is positioned with the electrode tip 111 at a predetermined position. The predefined position can be defined relative to the workpieces 1, 2 or relative to the robot 120. This can be, for example, a position where the electrode tip 111 is in contact with the workpieces 1, 2 (detectable, for example, by detecting a short circuit) or a position where it is assured that it is not in contact. Subsequently, in step S12, the robot 120 is controlled to move the electrode tip 111 in a defined scanning trajectory over at least a portion of the at least one workpiece 1, 2, thereby periodically generating information signals 73 with coordinates and orientations (e.g., x, y, z positions and alpha, beta, gamma angles) and providing a time stamp relative to a central clock. Preferably, the scanning trajectory extends at least partly perpendicular to the planned path of the weld seam and / or at least partly parallel to the surface of at least one of the workpieces 1, 2. In step S13, the electrode tip 111 is advanced until a short circuit is detected between the electrode tip 111 and the workpieces 1, 2, and the position of the electrode tip 111 along the wire feed motion axis when the short circuit occurs is stored, and the position is also recorded together with a central clock timestamp. In step S14, the electrode tip 111 is again retracted, for example by the wire feeder 141, until the short circuit is no longer present. Steps S13 and S14 are repeated along the scanning trajectory T, whereby the number of cycles (scanning density) may vary depending on the welding task, but may also be user adjustable. The cycle of advancing in S13, storing the position, and retreating in S14 is repeated at a frequency of, for example, 10 Hz to 500 Hz, preferably 30 Hz to 300 Hz, and particularly preferably 75 Hz to 125 Hz. The timestamps are preferably assigned at a frequency (eg, 1000 Hz) higher than both a) the frequency of steps S13+S14 and b) the frequency at which the information signal 73 of the robot 120 is received. In step S15, the acquired geometry data of the electrode tip 111 (i.e., stored positions with time stamps) and the robot coordinates of the robot 120 (position and angle from the information signal 73) are evaluated in order to obtain desired information regarding the geometry and / or position of at least one workpiece 1, 2, for example as described above with reference to Figure 4. In this way, the data are combined, in particular via a common time stamp, i.e., a common time base. In step S20, a specification of a welding task to be performed on at least one workpiece 1, 2 is received, for example together with the welding task via a data interface, data carrier, etc. Receiving S20 may be wired or wireless. In step S30, an output signal is generated that is designed to generate, set, or modify at least one parameter of the welding task to be performed based on the received specifications and the results of the scanning program, which may be done, for example, as described in detail above, with particular reference to Figures 1-6. Adjusting the parameters can serve the purpose of enabling the welding task to be performed perfectly, improving the expected quality of the workpiece to be produced in the welding task, providing improved documentation (e.g., information about the quality of the produced workpiece), improving the efficiency of performing the welding task (reducing the speed, reducing the waiting time between two welding tasks, etc.), and / or other purposes. In step S40, a welding task including or taking into account at least one generated, set or modified parameter is performed by the robot 120 and the welding torch 110. In particular, in step S40, at least one workpiece 1, 2 may be welded.

[0063] Figure 8 shows a schematic block diagram illustrating a computer program product 200 according to an embodiment of the present invention. The computer program product 200 comprises executable program code 250 adapted, when executed, to perform a method according to an embodiment of the present invention, in particular the method described with reference to Figure 7.

[0064] 9 shows a schematic block diagram illustrating a non-transitory computer-readable data storage medium 300 according to an embodiment of the present invention. The data storage medium 300 includes executable program code 350 adapted, when executed, to perform a method according to an embodiment of the present invention, in particular the method described with reference to FIG.

[0065] In the foregoing detailed description, various features are grouped together in one or more examples to improve the rigor of the description. However, it should be understood that the above description is merely illustrative and not limiting in any way. It is intended to cover all alternatives, modifications, and equivalents of the various features and embodiments. Many other examples will be readily and directly apparent to those skilled in the art upon review of the above description.

[0066] The embodiments have been chosen and described to best explain the principles underlying the invention and its possible applications in practice, thereby enabling those skilled in the art to optimally modify and utilize the invention and its various embodiments according to the intended use. It is further understood that units described as separate may be partially integrated with each other. [Explanation of symbols]

[0067] 1 Workpiece 2 Workpiece 3 Electrical Connection 71 Control Signal 72 Detection signal 73 Information Signal 74 Control Signals 75 output signals 100 Robot Welding System 110 Welding Torch 111 Electrode tip 112 Consumable wire electrode 113 Additional electrodes 120 Robot 121 Robot Arm 131 Sensor Unit 132 arithmetic units 140 Welding power source 141 Wire feeder 142 Short circuit detection device 143 Power Electronics 150 Holding device 200 Computer Programs 250 Program Code 300 Data storage media 350 Program Code D. Supply Channel t time Time points t1 and t2 T scan trajectory S10...S40 Method steps

Claims

1. a welding torch (110) with a consumable electrode (112); a robot (120) configured to guide the welding torch (110); a welding power supply (140) designed to create a voltage between a consumable electrode (112) and a second electrode (113) connectable to at least one workpiece (1, 2); A sensor unit (131) configured to perform a scanning program by a robot (120) and a welding torch (110), wherein the geometry of at least one workpiece (1, 2) is at least partially scanned and detected by a consumable electrode (112) of the welding torch (110), at least one position and / or orientation of the robot (120) is detected simultaneously, and the cycle is periodically repeated to detect the geometry of the at least one workpiece (1, 2), the cycle comprising: advancing the electrode tip (111) of the consumable electrode (112) until a short circuit between the consumable electrode (112) and at least one workpiece (1, 2) is detected via the second electrode (113), with the latter connected to at least one workpiece (1, 2); storing the position of the consumable electrode (112) at the time the short circuit is detected; and Retracting the electrode tip (111) until the short circuit is removed a sensor unit (131) including: a computing unit (132) configured to acquire specifications of a welding task to be performed on at least one workpiece (1, 2) and to generate, based on the acquired specifications and the results of the scanning program, an output signal (75) designed to generate or set at least one parameter of the welding task to be performed; A robotic welding system (100) comprising:

2. 10. The robotic welding system of claim 1, further comprising a welding power source, wherein the output signal is designed to set target, minimum, and / or maximum values ​​for parameters of the welding power source when performing a welding task to be performed.

3. 3. The robotic welding system (100) of claim 1 or 2, wherein the output signal (75) is adapted to set a target value, a minimum value, and / or a maximum value for the welding speed of the robot (120) when performing the welding task to be performed.

4. 4. The robot welding system of claim 1, wherein the output signal is adapted to set a target, minimum and / or maximum value for the angle of attack of the robot when performing a welding task to be performed.

5. 5. The robotic welding system (100) of claim 1, wherein the output signal (75) is adapted to adjust a welding position and / or a welding path of the robot (120) to perform a welding task to be performed.

6. 6. The robotic welding system (100) of claim 1, wherein the specification of the welding task to be performed comprises at least one requirement, and wherein the computing unit (132) is adapted to determine whether the at least one requirement is met based on the results of the scanning program.

7. 7. The robot welding system of claim 6, wherein if the computing unit reaches the conclusion that at least one requirement is not met, an output signal is generated such that the robot and / or a controllable holding device for at least one of the at least one workpiece is moved so that the requirement is met as far as possible or completely.

8. 8. The robotic welding system (100) of claim 7, wherein the welding task includes at least two workpieces (1, 2), and the at least one requirement includes a requirement for relative positioning between the at least two workpieces (1, 2).

9. 9. The robotic welding system (100) according to any one of claims 1 to 8, wherein the output signal (75) is designed to generate information on the expected quality of the result of the performed welding task as a parameter of the welding task to be performed.

10. The at least one requirement includes a requirement for the expected quality of the welding task performed; an output signal (75) designed to indicate the end of the welding task of at least one workpiece (1, 2) if the expected quality does not correspond to a predetermined minimum quality; A robotic welding system (100) according to claim 6 or 7 and claim 9.

11. the at least one requirement includes a requirement regarding a geometric property possessed by at least one of the at least one workpiece (1, 2); an output signal (75) designed to indicate the end of the welding task for at least one workpiece (1, 2) when the geometric characteristic is not present; The robotic welding system (100) of any one of claims 6 to 8 or 10.

12. The robotic welding system (100) according to any one of the preceding claims, wherein the cycle is repeated at a frequency of 10 Hz to 500 Hz, preferably 30 Hz to 300 Hz, particularly preferably 75 Hz to 125 Hz.

13. 13. The robotic welding system (100) of claim 1, wherein the sensor unit (131) is adapted to receive an information signal (73) of the robot (120) in addition to a position signal including the position of the electrode tip.

14. 14. The robot welding system (100) of claim 13, wherein the sensor unit (131) is configured to provide time stamps for all position and / or information signals (73) or at least for position and / or information signals (73) that do not have their own time stamps, so that a relationship is established between the position and orientation of the robot (120) in its time and coordinate system, on the one hand, and the stored position of the electrode tip of the wire electrode (112) on the other hand, via a common time stamp.

15. 15. The robotic welding system (100) of claim 14, wherein movement of the robot (120) along a scanning path to scan the at least one workpiece (1, 2) occurs independently of cycling of the wire electrode (112).

16. A method of operating a robotic welding system (100) having a robot guiding a welding torch (110) having a consumable electrode (112), comprising the steps of: connecting a second electrode (113) to at least one workpiece (1, 2) and forming a voltage between the consumable electrode (112) and the second electrode (113); Executing a scanning program by the robot (120) and the welding torch (110), wherein the geometry of at least one workpiece (1, 2) is at least partially scanned and detected by a consumable electrode (112) of the welding torch (110), and at least one position and / or orientation of the robot (120) is simultaneously detected, and the cycle is periodically repeated to detect the geometry of the at least one workpiece (1, 2), the cycle comprising: advancing the electrode tip (111) of the consumable electrode (112) until a short circuit between the consumable electrode (112) and at least one workpiece (1, 2) is detected via the second electrode (113), with the latter connected to at least one workpiece (1, 2); storing the position of the consumable electrode (112) at the time the short circuit is detected; and Retracting the electrode tip (111) until the short circuit is removed Step (S10) obtaining (S20) a specification of a welding task to be performed on at least one workpiece (1, 2); Producing (S30) an output signal (75) designed to generate, set or modify at least one parameter of the welding task to be performed based on the received specifications and the results of the scanning program.

17. 17. The method of claim 16, comprising performing (S40) a welding task with a robot (120) and a welding torch (110) that includes at least one generated, set, or modified parameter.

18. 18. The method of claim 17, wherein the output signal (75) is designed to automatically select a suitable welding process type from a list of welding process types, and the step of performing the welding task (S40) is performed by the selected welding process type.

19. A computer program product (200) comprising executable program code (250) adapted to perform the method according to any one of claims 16 to 18 when executed.

20. A non-transitory computer-readable data storage medium (300) comprising executable program code (350) adapted, when executed, to perform the method of any one of claims 16 to 18.

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