Robot welding system and method for operating a robot welding system

Abstract

The invention relates to a robot welding system (100) and to a method for operating a robot welding system. The robot welding system (100) comprises: a welding torch (110) with a consumable electrode (112); a robot (120) which is configured to guide the welding torch (110); a sensor unit (131) which is configured to carry out, by means of the robot (120) and the welding torch (110), a scanning program in which a geometry of at least one workpiece (1, 2) is scanned and captured by means of the consumable electrode (11), wherein at the same time at least one position and / or orientation of the robot (120) is captured, and wherein to capture the geometry of the at least one workpiece (1, 2) a cycle of the extension and retraction of an electrode tip (111) of the consumable electrode (112) is periodically repeated; and a computing unit (132) which is configured to receive a specification of a welding task to be performed on the at least one workpiece (1, 2) and, based on the received specification and on a result of the scanning program, to generate an output signal which is designed to generate or set at least one parameter of the welding task to be performed.

Description

[0001] Robot welding system and method for operating a robot welding system

[0002] Technical area

[0003] The present invention relates to a robot welding system with a robot which guides a welding torch with a consumable electrode, and to a method for operating a robot welding system with such a robot.

[0004] Background of the invention

[0005] Robotic welding systems are used to process one or more workpieces in a single welding process. Even if the basic shapes of the workpieces are often assumed to be known, it can happen that individual workpieces or the arrangement of two or more workpieces relative to each other do not meet the expected specifications. In robotic welding systems, which are particularly advantageous when welding processes can be automated at high speed, such a situation can lead to delays or results that do not meet quality requirements.

[0006] It is known from EP 1233 845 B1 that by moving a workpiece or several workpieces using a welding wire and simultaneously monitoring the occurrence of a short circuit, coordinates of, for example, a weld center can be determined.

[0007] There is still a need for improved

[0008] Robot welding systems and methods for operating such robot welding systems in which unexpected or problematic properties of welding tasks can be detected and, ideally, corrected as automatically as possible. A welding task is understood to mean, in particular, an arrangement of at least one workpiece to be welded, the alignment of workpieces, their quality properties, and the like, as well as the welding processes to be performed on this arrangement, including all associated parameters and properties.

[0009] Summary of the invention

[0010] It is therefore an object of the present invention to provide an improved robot welding system and a corresponding method for controlling such a robot welding system, which solves the above-mentioned problem.

[0011] Accordingly, according to a first aspect of the present invention, a robot welding system is provided comprising: a welding torch with a consumable electrode (or: welding wire); a robot which is configured to guide the welding torch; a sensor unit which is configured to carry out a scanning program by means of the robot and the welding torch, in which a geometry of at least one workpiece is scanned and detected at least in sections by means of the consumable electrode of the welding torch, wherein at least one position and / or orientation of the robot is detected simultaneously;and a computing unit which is configured to receive a specification of a welding task to be performed on the at least one workpiece and, based on the received specification and on a result of the scanning program, to generate an output signal which is configured to determine at least one parameter of the welding task to be performed;

[0012] To create and set the welding task.

[0013] The welding power source can in particular be designed to generate a voltage between the consumable electrode and a second electrode which can be connected to at least one workpiece.

[0014] The sensor unit can be configured such that, in order to detect the geometry of the at least one workpiece, a cycle is periodically repeated, which cycle comprises advancing and retracting an electrode tip of the consumable wire electrode.

[0015] In particular, the cycle, which is repeated periodically, may comprise:

[0016] Advancing an electrode tip of the consumable electrode until a short circuit between the consumable electrode and the at least one workpiece is detected via the second electrode while the latter is connected to the at least one workpiece, storing the position of the consumable electrode at the time of the detected short circuit, and withdrawing the electrode tip until the short circuit breaks.

[0017] The geometry of each workpiece can include internal and / or external geometric properties of the workpiece. Internal geometric properties include, for example, its dimensions, its outer contour, and the like. External geometric properties of the workpiece include, for example, its position and / or arrangement in three-dimensional space, usually with respect to a fixed coordinate system, such as the coordinate system used by the welding robot.

[0018] Generating parameters means, for example, generating information or signals related to or associated with the welding task, for example generating warning signals, filling data fields with information, generating digital flags ("flagging") in a digital report on the performance of the welding task, and the like.

[0019] Setting parameters can be understood as either setting parameters (or parameter values) for the first time or changing or adjusting parameters (or parameter values) or selecting options from a list.

[0020] The parameter of the welding task to be performed can, for example, also be a welding process type, which is automatically selected from a list of welding process types. For example, detecting the geometries of two workpieces may reveal that there is a gap between them, and based on this, a suitable welding process type can be selected, e.g., a pulse process, a cold metal transfer (CMT) process, or the like. All parameters for the selected welding process type can then be set automatically or suggested to the user.

[0021] The robot can, in particular, be a robot arm or a larger robot unit, which can, in particular, have a robot arm for guiding the welding torch. The position and / or orientation of the robot is to be understood in particular with respect to that part of the robot that guides the welding torch. In the case of a multi-jointed robot arm, the orientation can, for example, comprise a plurality of angles in the coordinate system of each joint, and the like.

[0022] When reference is made here to "units," it is understood that this does not necessarily mean that such units are implemented as separate entities. In cases where such units are implemented as software, the units may be implemented as program code sections or program code components, which may be distinguishable from one another, but which may also be interwoven. Likewise, in cases where one or more units are implemented as hardware, the functions of one or more units may be implemented by one and the same hardware component.

[0023] Alternatively or additionally, different functions of a single unit or different functions of different units can be implemented on one or more separate hardware components, which therefore do not necessarily have to be in a 1:1 relationship with the units. In this sense, any device, system, method, etc., that has all the properties and functions attributed to a specific unit can be understood as having, representing, or implementing such a unit. In particular, it may be possible for all units to be implemented as program code that is executed on a computing device, for example, by a server or a cloud computing platform.

[0024] The robot welding system can also be arranged locally, for example the sensor unit and / or the computing unit can be integrated into the robot and / or into a

[0025] Welding power source of the robot welding system.

[0026] Furthermore, the invention provides a method for operating a robot welding system with a robot which guides a welding torch with a consumable electrode, the method comprising:

[0027] Carrying out a scanning program by means of the robot and the welding torch, in which a geometry of at least one workpiece is scanned and detected at least in sections by means of the consumable electrode of the welding torch, wherein at least one position and / or orientation of the robot is detected at the same time;

[0028] Obtaining a specification of a welding task to be performed on the at least one workpiece;

[0029] Generating an output signal based on the obtained specification and on a result of the scanning program, which is designed to generate, set or change at least one parameter of the welding task to be performed.

[0030] The method may further comprise the step of connecting a second electrode to at least one workpiece and forming a voltage between the consumable electrode and the second electrode.

[0031] To detect the geometry of the at least one workpiece, a cycle is advantageously repeated periodically, which comprises advancing and retracting an electrode tip of the consumable electrode.

[0032] The cycle, which is repeated periodically, may in particular comprise: advancing an electrode tip of the consumable electrode until a short circuit between the consumable electrode and the at least one workpiece is detected via the second electrode while the latter is connected to the at least one workpiece, storing the position of the consumable electrode at the time of the detected short circuit, and retracting the electrode tip until the short circuit is broken.

[0033] According to some advantageous embodiments, further developments, or variants, the robot welding system also comprises a welding power source. The output signal can be configured to set a target value, a minimum value, and / or a maximum value for a parameter of the welding power source for performing the welding task to be performed. Entire parameter sets consisting of multiple parameters can also be set (e.g., initially defined or changed).

[0034] The parameter can, for example, be an electrical or a non-electrical parameter. The parameter can be a parameter of the welding power source, the robot, or another part or element or of a method or process of the welding system. An electrical parameter can be a welding current, a welding voltage, a welding power, and / or the like. Non-electrical parameters include, for example, a gas flow rate, a gas pre- and post-flow time, a wire retraction length, a wire feed speed, and / or the like. Further parameters are known to those skilled in the art. According to some advantageous embodiments, further developments, or variants, the output signal can be designed to set a target value, a minimum value, and / or a maximum value for a welding speed of the robot when performing the welding task to be performed.For example, the scanning program can be used to determine the depth and / or width of a gap to be welded, which can be used to determine the required volume or A dimension (in the case of a fillet weld) of filler welding material from the consumable electrode (or welding wire electrode). This allows an optimal welding speed to be calculated, particularly in combination with the electrical parameters of the welding power source and optionally also with knowledge of the properties of the electrode, i.e., the welding wire to be consumable. In the robot welding system, this welding speed can then be adjusted accordingly using the output signal, and the robot can thus be controlled to operate the welding torch at this calculated, optimal welding speed while performing the welding task.

[0035] According to some advantageous embodiments, further developments, and variants, the output signal is designed to set a target value, a minimum value, and / or a maximum value for an angle of attack of the robot when performing the welding task to be performed. The robot can then be controlled by means of the output signal to assume the corresponding angle of attack and / or to perform the welding task to be performed permanently or at least partially at the set angle of attack, depending on the requirements. As already mentioned, the scanning program can, for example, determine the geometry of a fillet weld or a butt joint, and based on this, the computing unit can calculate an optimal angle of attack for the welding task to be performed.The angle of attack can also be a temporal sequence of angles of attack, i.e. an angle of attack as a function of time during the execution of the welding task, in particular if the optimal angle of attack changes once or several times during the welding task to be carried out.

[0036] According to some preferred embodiments, variants, or further developments of embodiments, the output signal is designed to set, in particular to change, a welding position and / or a welding path of the robot for performing the welding task to be performed. This can be advantageous, for example, if it is determined based on the scanned geometry of the at least one workpiece that the workpiece is not in a desired position, for example, not in a position that was used for teaching the robot movement. The robot can have a correction program to which only the actual position of the workpiece needs to be communicated, for example in explicit coordinates of the actual position and / or in the form of information about a deviation of the actual position (actual position) from an expected, previously determined, or preset position (target position).The correction program then automatically adjusts the taught welding position and / or welding path accordingly.

[0037] The presence of a workpiece in an incorrect position and / or incorrect alignment can be due, for example, to aging of a holding device for at least one workpiece, to shape deviations of at least one workpiece itself, and / or to batch tolerances. In an automatic welding cell, the detection of the geometry of the workpiece, in particular its arrangement and / or orientation in space, can be performed, for example, before each welding task, before or for each workpiece, after a predetermined number of welding tasks or workpieces, or at regular intervals (e.g., once a day).

[0038] According to some advantageous embodiments, further developments, or variants, the specification of the welding task to be performed includes at least one requirement. The computing unit can be configured to determine, based on the result of the scanning program, whether the at least one requirement is met or not. As will be explained below, the result of whether the at least one requirement is met or not, or which and / or how many of several requirements are met or not, can be used in a variety of ways to profitably control the robot welding system.Determining whether a requirement is met or not may include, first, determining that the requirement is met in any case, and / or second, determining that the requirement can be met but that permissible parameter changes to the robot welding system are necessary, and / or third, determining that a requirement is not feasible under any circumstances, either because no possible or permissible parameter change exists that would make the requirement fulfillable.

[0039] Changeable (or: customizable) parameters of the

[0040] Robot welding system parameters may include, for example: welding power source parameters (current, voltage, power, gas flow rate, etc.); welding speed and / or acceleration of the robot;

[0041] Robot angle of attack;

[0042] Welding position and / or welding path; and / or the like.

[0043] The inadmissibility of a parameter change that is otherwise possible for the robot welding system may be due, for example, to the fact that a current user of the robot welding system does not have the appropriate authorization or that the robot welding system is not currently enabled to change the necessary parameters. The robot welding system may include a user interface that allows a user to unlock one or more functions, for example, the functions required to change the parameters for performing the welding task, in particular for a fee.

[0044] According to some advantageous embodiments, further developments, or variants, the robot welding system is configured such that, if the computing unit concludes that the at least one requirement cannot be met, the output signal is generated such that the robot and / or a controllable holding device of at least one of the at least one workpiece is moved such that the requirement is met as well as possible or completely. This means that the output signal can be generated such that feasible changes that enable the at least one requirement to be met are automatically implemented, or at least such changes are automatically implemented that result in the best possible fulfillment of the requirement. For each requirement, it can be separately specified whether it must be met 100 percent, or whether partial fulfillment of the requirement is also permissible.

[0045] The robot welding system can be set up in such a way that the welding task to be performed is only carried out automatically if each of the at least one requirements is fully or at least sufficiently met. If several welding tasks are planned and one of them cannot be carried out, it can be provided that those and only those welding tasks are carried out whose requirement(s) are fully (or, depending on the variant, at least sufficiently) met. Alternatives can also be provided, i.e. in principle a welding task A can be planned, but if this cannot be carried out due to incomplete or inadequate fulfillment of its requirement(s), a welding task B should be carried out instead. The welding task B can, for example, comprise a different type of welding process, a different type of seam and / or the like.

[0046] According to some advantageous embodiments, further developments or variants, the welding task comprises at least two workpieces. The at least one requirement can comprise a relative positioning between the at least two workpieces. A requirement can, for example, comprise a maximum width of a gap between two plate-shaped workpieces in the butt joint, a maximum angle between two workpieces and / or the like. The requirement can either be a yes / no requirement, i.e. it can either be met or not, it can be a the more the better requirement, or a combination thereof. With a yes / no requirement, for example, it can be required that the gap of the butt joint be a maximum of x mm. With a the more the better requirement, it can be provided that the gap should be as small as possible.In a combined requirement, it can be specified that the gap should be as small as possible, but no more than x mm. The output signal can accordingly be generated such that the robot and / or a controllable holding device for at least one of the at least two workpieces is or are controlled in such a way that the requirement is met.

[0047] 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 a result of the welding task being performed. The expected quality can be based, for example, on the geometric dimensions of the at least one workpiece or the relative arrangements of at least two workpieces to one another, which can be known due to 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 capabilities of the robot welding system, in particular of the welding torch, information about properties of the at least one workpiece such as material properties, information about a time available for the welding task to be carried out and / or the like.

[0048] According to some advantageous embodiments, further developments, or variants, the at least one requirement comprises a requirement regarding the expected quality of the welding task being performed. The output signal can be configured to instruct termination of the welding task for the at least one workpiece if the expected quality does not correspond to a predetermined minimum quality. In this way, valuable time and resources of the robot welding system can be avoided from being wasted on an inferior product. Preferably, the expected quality of the welding task being performed is calculated after all feasible parameter changes have been adapted to maximize the fulfillment of all existing requirements for the welding task.

[0049] According to some advantageous embodiments, further developments or variants, the at least one requirement comprises a requirement for a geometric property of at least one of the at least one workpiece. The output signal can be designed to instruct an abort of the welding task for the at least one workpiece if the geometric property is not present. The geometric property of the at least one workpiece can be determined in particular by the scanning program. In this way, a time-consuming and / or costly prior inspection of workpieces to be welded can be omitted and can instead be carried out automatically by the robot welding system as part of the scanning program. A geometric property to be fulfilled can, for example, be a desired minimum thickness or maximum thickness of a plate-shaped workpiece (sheet metal).

[0050] According to some preferred embodiments, variants, or refinements of embodiments, the cycle is repeated at a frequency between 10 Hz and 500 Hz, preferably between 30 Hz and 300 Hz, particularly preferably between 75 Hz and 125 Hz. According to some preferred embodiments, variants, or refinements of embodiments, the sensor unit is configured to receive, in addition to position signals with the positions of the electrode tip, information signals from the robot. The information signals from the robot can, for example, indicate a respective position and / or orientation of the robot.

[0051] The sensor unit can be configured to provide all position signals and / or information signals (or at least those position signals and / or information signals which do not have their own time stamp) with a time stamp, so that a connection is established via the common time stamp between the positions and orientations of the robot in its time and coordinate system on the one hand, and the stored positions of the electrode tip of the wire electrode on the other hand.

[0052] Advantageously, the robot moves along a scanning path for scanning the at least one workpiece independently of the cycle of the wire electrode.

[0053] According to some advantageous embodiments, further developments or variants, the method further comprises carrying out the welding task comprising the at least one generated, set or changed parameter by means of the robot and the welding torch.

[0054] The output signal can be configured to automatically select a suitable welding process type from a list of welding process types. The welding task can be performed using the selected welding process type. Further information, which may represent parameters of the welding task, can include, for example, information about which parameter changes were made to ensure that at least one requirement of the specification of the welding task to be performed could be met and / or the like.

[0055] According to a further aspect, the invention provides a computer program product comprising executable program code which, when executed, is adapted to perform the method of an embodiment of the present invention.

[0056] According to a further aspect, the invention provides a non-transitory, computer-readable data storage medium comprising executable program code which, when executed, is configured to perform the method of one embodiment of the present invention. The data storage medium may be, for example, a hard disk, a solid-state memory, a CD, a DVD, a memory card, and the like.

[0057] According to a further aspect, the invention provides a data stream or a data structure which comprises executable program code or is adapted to generate executable program code, and wherein the executable program code is adapted, when executed, to perform the method of an embodiment of the present invention.

[0058] Further preferred embodiments, variants, and further developments of embodiments emerge from the subclaims and from the description with reference to the figures. Brief description of the figures

[0059] The invention is explained in more detail below using exemplary embodiments in the figures of the drawings. The partially schematic representation shows:

[0060] Fig. 1 is a schematic diagram of a robot welding system according to a first embodiment of the present invention;

[0061] Fig. 2a) an illustrative representation of the execution of a scanning program;

[0062] Fig. 2b) a first result of the scanning program from Fig. 2a);

[0063] Fig. 3a) an illustrative representation of the execution of another scanning program;

[0064] Fig. 3b) a first result of the scanning program from Fig. 3a);

[0065] Fig. 4a) to Fig. 4f) various graphs to illustrate possible signal processing and use of the results of a sampling program;

[0066] Fig. 5a) to Fig. 5n) are schematic diagrams to illustrate possible welding situations or problems in the arrangement or properties of workpieces;

[0067] Fig. 6a) to Fig. 6i) are schematic diagrams to illustrate further possible welding situations or problems in the arrangement or properties of workpieces;

[0068] Fig. 7 is a schematic flow chart for explaining a method according to another embodiment of the present invention;

[0069] Fig. 8 is a schematic block diagram for explaining a computer program product according to another embodiment of the present invention; and

[0070] Fig. 9 is a schematic block diagram for explaining a data storage medium according to still another embodiment of the present invention.

[0071] In all figures, identical or functionally equivalent elements and devices are provided with the same reference numerals, unless otherwise indicated. The designation and numbering of the process steps does not necessarily imply a sequence, but serves to facilitate differentiation, although in some variants the sequence may also correspond to the numbering sequence.

[0072] Detailed description of the characters

[0073] Fig. 1 shows a schematic representation of a robot welding system 100 according to a first embodiment of the present invention. The robot welding system 100 comprises a welding torch 110, which guides a consumable wire electrode 112 (i.e., a welding wire), and which, in turn, is guided by a robot 120, in particular a robot arm 121, of the robot welding system 100. A welding power source 140 of the robot welding system 100 is designed to generate a voltage between the consumable wire electrode 112 and a second electrode 113, which can be connected to a workpiece 1, 2.

[0074] One or more holding devices 150, one or more of which may in turn be controllable, may also be provided for holding and / or arranging at least one of the workpieces 1, 2. Such holding devices 150 may also be part of the robot welding system 100 and advantageously also be controllable by it. A holding device 150 may, for example, be another robot, e.g., a robot arm.

[0075] The robot welding system 100 further comprises a sensor unit 131, which is designed and configured to execute a scanning program using the robot 120 and the welding torch 110. In this program, the geometry of at least one workpiece 1, 2 is scanned and detected at least in sections using 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, using an information signal 73 from the robot 120. In combination, it is thus possible to determine the geometric properties (length, height, size, outer contour) and the relative arrangement of, for example, several workpieces 1, 2 to one another.

[0076] In the situation shown in Fig. 1, the sensor unit 131 is integrated into the welding power source 140, for example, but other arrangements are also conceivable, for example, integration into the robot 120, a separate arrangement in a separate housing, and / or a remotely arranged sensor unit 131 (e.g., implemented by a remotely arranged server, a cloud computing platform, or the like).

[0077] To execute the scanning program, the sensor unit 131 can, in particular, comprise a wire feed device 141 of the robot welding system 100, or the wire feed device 141 and the sensor unit 131 can be configured such that the sensor unit can control the wire feed device 141, in particular to execute the scanning program. For this purpose, the sensor unit 131 can send control signals 71 to the wire feed device 141. In the variant shown, the wire feed device 141 is part of the welding power source 140. Other embodiments are known to those skilled in the art; therefore, they will not be discussed in detail here.

[0078] The sensor unit 131 may also comprise a voltage measuring device (among others) for short-circuit detection or be configured to receive and evaluate detection signals 72 of a voltage measuring device 142 of the welding power source 140 (as shown in Fig. 1).

[0079] To execute the scanning program, the sensor unit 131 can instruct the wire feed device 141 to advance the consumable wire electrode 112 at a predefined speed until it detects a short circuit between the consumable wire electrode 112 and the workpiece 1 (via the additional electrode 113) based on the detection signals 72 of the voltage measuring device 142. An electrical connection 3 between the workpieces 1, 2 (usually provided by a clamping device or holding device) enables short circuits between the consumable wire electrode 112 and both workpieces 1, 2 to be detected.

[0080] The corresponding position ("starting position") of the wire electrode 112 upon the occurrence of the short circuit can be measured and stored, for example, via a motor encoder of the wire feed device 141 and / or by the sensor unit 131. The first detected position of the workpiece 1 can be defined as a reference distance, e.g., as a zero line. The electrode tip of the wire electrode 112 is then retracted until the short circuit breaks, and the cycle of advancing, storing the position, and retracting is repeated periodically, e.g., at a frequency between 10 Hz and 500 Hz, preferably between 30 Hz and 300 Hz, particularly preferably between 75 Hz and 125 Hz. The position information of the welding wire is recorded each time a short circuit occurs.

[0081] In addition to the positions of the electrode tip, the sensor unit 131 also receives the information signals 73 from the robot 120. All signals converging at the sensor unit 131 can be provided with a time stamp by the sensor unit 131, so that a connection is established via the common time stamp between the positions and orientations of the robot 120 in its time and coordinate system on the one hand, and the stored positions of the electrode tip of the wire electrode 112 on the other.

[0082] Alternatively, the position signals and / or the information signals 73 of the robot can also be provided with their own time stamps, whereby the sensor unit 131 only provides time stamps to those signals that do not have their own time stamps and calculates a one-to-one correlation between the / all received and / or self-generated time stamps, which it subsequently uses for the temporal correlation of the positions of the electrode tip and the position and orientation of the robot 120. The variant in which the sensor unit 131 provides all signals with time stamps is described in more detail below, without the invention being limited thereto. However, the term "common time stamps" always means that one of the aforementioned (or other known) methods for correlating the signals and time stamps is used to obtain temporally correlated signals or positions and orientations.

[0083] Thus, as part of the scanning process, the robot 120 can be instructed (for example, by the sensor unit 131 or another element of the robot welding system 100) to move the wire electrode 112 along a scanning path in a direction perpendicular to the wire feed direction. Since the data is linked via the common timestamp, the—usually significantly slower—movement of the robot 120 can occur independently of the cycle of forward and backward movement of the wire electrode 112.

[0084] Fig. 2a) to Fig. 3b) explain this procedure.

[0085] Both in Fig. 2a) and in Fig. 3a), the welding torch 110 (more precisely: the tip of the contact tube of the welding torch 110) is shown both at a first time t1 and at a later time t2. At time t1, the electrode tip 111 of the consumable wire electrode 112 touches a first workpiece 1, which, according to the welding task in Fig. 2a), is to be welded to a second workpiece 2 in a flanged seam, and according to the welding task in Fig. 3a), is to be welded in a fillet weld.

[0086] Fig. 2b) and Fig. 3b) show the feed path D of the electrode tip 111, traveled from the starting position at time t1 to the end position of the scanning program at time t2, as a function of time t in seconds. 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 performed (in Fig. 2a) and 3a) into the plane of the drawing). The scanning trajectory T is preferably a straight line in space. For some welding tasks, such as that of Fig. 2a), it is advantageous if the scanning trajectory T additionally extends at least partially parallel to at least one surface of at least one workpiece 1, 2.

[0087] In Figs. 2b) and 3b) it is already schematically evident how comprehensive geometric information about the geometric properties of both the workpieces 1, 2 and their arrangement relative to one another can be generated in this way.

[0088] Fig. 4a) to f) illustrate the further processing in more detail using the welding task shown in Fig. 2a) and Fig. 2b). The association or correlation of the various signals across the common horizontal axis based on the common time stamps is clearly visible.

[0089] Fig. 4a) shows the raw signal as it is generated according to the procedure described with reference to Fig. 2a) to Fig. 3b). Fig. 4b) shows a filtered (smoothed) signal based thereon. Fig. 4c) shows how the actual geometry of the welding situation (i.e. of the workpieces 1, 2 and their arrangement) can be extracted from the signal from Fig. 4b). For this purpose, the sensor unit 131 can have information about the welding task, for example information about which welding situation should prevail and / or which type of weld seam should be created in the welding task. Thus, the sensor unit 131 can have ideal parameterizations of curves, as shown in Fig. 4c), depending on the welding task and / or weld seam, for which the signal from Fig. 4b) is analyzed and processed using mathematical methods, e.g. filtered and / or fitted, in order to determine the existing shape and configuration of the workpieces.

[0090] Fig. 4d) shows the positions of robot 120 as a function of time in X, Y, and Z coordinates of a predefined coordinate system, which can, for example, be fixedly connected to robot 120. Fig. 4e) correspondingly shows the orientation of robot 120 at three angles: alpha, beta, and gamma. This information can be provided to sensor unit 131 either via information signals 73 from robot 120 to sensor unit 131. Alternatively, sensor unit 131 can also be configured to send control signals 74 for moving robot 120 to robot 120. In this case, the position, orientation, etc. of robot 120 can be detected based on control signals 74. Fig. 4f) shows a tool center point velocity of robot 120.

[0091] Referring again to Fig. 1, the robot welding system 100 further comprises a computing unit 132 configured to obtain a specification of a welding task to be performed on the at least one workpiece 1, 2 and, based on the obtained specification and a result of the scanning program, to generate an output signal 75 configured to generate or adjust at least one parameter of the welding task to be performed. Depending on which parameter is generated or adjusted, the output signal 75 can be sent to various elements, for example, to the robot 120, to power electronics 143 of the welding power source 140, to one or more holding devices 150, and / or the like.

[0092] The parameter or the plurality of parameters may, in particular, as already explained above, be parameters of the welding power source 140 (current, voltage, power), a welding speed and / or acceleration of the robot 120, one or more angles of attack of the robot 120, a welding position or a welding path, a welding process type and / or the like, and in each case again a minimum value, a maximum value, a setpoint value and so on.

[0093] The number and type of parameter changes depend on the welding task and the detected geometries. For example, the computing unit 132 may have information that the welding task involves welding a fillet weld with a consumable wire electrode 112. The geometry of the welding situation detected by the scanning program may, for example, include an angle between the workpieces 1, 2, which requires an adjustment of the angle of attack of the robot 120.

[0094] Similarly, the scanning program can detect the width of a gap in a butt joint, calculate the required amount of melted material of the consumable wire electrode 112 based on this, and in turn, determine the welding speed (or

[0095] Movement speed of the robot 120 along the weld seam), a welding current (electrical output current of the welding power source), a welding position, a welding path, a welding process type, and the like can be set (e.g., adjusted).

[0096] The computing unit 132 can also have information about all changeable parameters, as well as requirements for the welding task. For example, it can be provided that the angle between the workpieces 1, 2 for a fillet weld, such as in Fig. 3a), is ideally 90°.

[0097] If the sensor unit 131 determines, for example, by means of the scanning program that the angle is currently 80°, various possibilities exist. In the event that the computing unit 132 has access to a controllable holding device 150 for at least one of the workpieces 1, 2, by means of which the angle can be changed, it can be provided that the computing unit 132 controls this controllable holding device 150 by means of the output signal 75 to set the angle to 90° if possible. If the welding task includes a tolerance for the angle, for example, allowing a deviation of + / - 5°, the holding device 150 can be controlled to change the angle to at least 85° to 95°, whereby the set angle should be as close to 90° as possible.

[0098] In other cases, the welding task may include further requirements and / or information about the quality of the welding task to be performed. For example, it may specify that an angle of 89 O-91° allows the welding task to be completed with high quality, an angle between 85° and 95° allows the welding task to be completed with reduced quality, and any other angle does not allow for acceptable quality. In this case, it can be provided that the computing unit 132 first controls the holding device 150 to create an angle as close to 90° as possible. If the result is precisely known, the process can continue; if not, the computing unit 132 can instruct the sensor unit 131 to execute another scanning program to record the result of the control of the holding device 150. This can be done several times if necessary until no further improvement is possible. Based on the finally set angle, it can then be determined whether the welding task can be completed with high quality, reduced quality, or unacceptable quality, and whether the welding task should still be carried out.It can therefore also be provided that the welding task is aborted if an acceptable quality cannot be achieved.

[0099] The welding task may include or specify a data structure in which a report on the completed welding task is generated by the robotic welding system 100. This report may include information about the final quality of the completed welding task (or, in other words, the finished welded workpiece).

[0100] Fig. 5 and Fig. 6 serve to explain various possible welding situations, how the scanning program can detect them, and what conclusions can be drawn from them. The welding situations shown do not necessarily have to be faulty, but can also be desired in this form, for example if a certain gap width, a certain offset between two workpieces, etc. is desired. If a desired welding situation exists, a parameter can be generated which indicates that this was the case, for example for downstream quality control. In the event that the existing situations are undesirable (e.g. a gap, an offset, an angle, etc. is present although none should be there, or vice versa), the parameters of the welding task can be adjusted accordingly, as described above and below, in order to improve the result of the welding task.

[0101] Fig. 5a) to 5d) illustrate a welding task with a fillet weld. In this case, displacement of one of the workpieces relative to the other may occur (Fig. 5a)), the vertical workpiece may not be flush with the horizontal workpiece (Fig. 5b), Fig. 5c)), or a gap may occur between the workpieces (Fig. 5d)).

[0102] Fig. 5e) to 5g) illustrate a welding task with a flanged seam. This may involve a gap (Fig. 5e), Fig. 5g)) or a height offset between the two workpieces (Fig. 5f)).

[0103] Fig. 5h) to 5k) illustrate a welding task with an overlap seam. In this case, there may be a horizontal displacement (Fig. 5h)), one of the workpieces may be degraded, for example, have an unclean edge (Fig. 5i)), a gap and / or a non-zero angle may occur between the workpieces (Fig. 5j)), or there may be bevels in front of the weld edge (Fig. 5k)). The same welding situations can occur in three-sheet joints, in each case between two adjacent sheets (workpieces).

[0104] In some variants, degraded workpieces detected by the scanning program may also result in the welding task not being performed (i.e., aborted) on this or these specific workpieces due to corresponding requirements contained in the welding task specification. Alternatively, the welding task may still be performed, with the condition of the workpieces and / or the quality of the final welded workpiece being recorded in the report on the completed welding task.

[0105] Fig. 51) to 5n) illustrate a welding task with a V-seam, either with or without a gap. Here, the workpieces can be adjacent to each other without a gap (Fig. 51)) or separated by a gap (Fig. 5n)), or there can be a vertical offset between the two workpieces (Fig. 5m)) or an angular offset (not shown).

[0106] Fig. 6a) to 6c) illustrate a welding task with a Y-seam. The notch can be symmetrical (Fig. 6a)), there can be an offset between the workpieces (Fig. 6b)), or there can be a gap between the workpieces (Fig. 6c)).

[0107] Figs. 6d) to 6f) illustrate a welding task involving a round bar on a sheet metal. The round bar may be resting on the sheet metal (Fig. 6d)), or there may be a gap between the round bar and the sheet metal (Fig. 6e)). However, the scanning program may also detect that the round bar, as one of the workpieces, has incorrect geometric properties, such as the wrong radius or a deviation from a circular shape (Fig. 6f)).

[0108] Fig. 6g) to 6i) illustrate a welding task with a butt weld. The workpieces can be flush with each other (Fig. 6g)) or separated by a gap (Fig. 6i)). The geometric properties of a bevel on a workpiece edge can also be recorded (Fig. 6h)), and thus, for example, whether it has undesirable properties (incorrect size, incorrect angle, etc.).

[0109] Fig. 7 shows a schematic flow chart for explaining a method according to an embodiment of the present invention, namely a method for operating a robot welding system with a robot which guides a welding torch with a consumable electrode.

[0110] In a step S10, a scanning program is executed by means of the robot 120 and the welding torch 110, in which a geometry of at least one workpiece 1, 2 is scanned and detected at least in sections using the consumable wire electrode 112 of the welding torch 110, while 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 Figs. 1 to 6.

[0111] In particular, the following steps can be carried out within the scanning program, particularly in numerical order:

[0112] In a step S11, the welding torch 110 is positioned with the electrode tip 111 at a predefined position. The predefined position can be defined relative to a workpiece 1, 2 or relative to the robot 120. This can be, for example, a position at which the electrode tip 111 rests against a workpiece 1, 2 (detectable, for example, by means of short-circuit detection), or a position at which it is ensured that there is no contact. Subsequently, in a step S12, the robot 120 is controlled to move the electrode tip 111 in a defined scanning trajectory over at least a portion of at least one workpiece 1, 2, wherein information signals 73 with the coordinates and orientations (for example, x, y, z positions as well as alpha, beta, gamma angles) are regularly generated and provided with a time stamp relative to a central clock.Preferably, the scanning trajectory runs at least partially perpendicular to the planned course of the weld seam and / or at least partially parallel to at least one surface of a workpiece 1, 2.

[0113] In a step S13, the electrode tip 111 is advanced until a short circuit between the electrode tip 111 and a workpiece 1, 2 is detected, and a position of the electrode tip 111 along the axis of the wire feed movement at the occurrence of the short circuit is stored, wherein the position is also recorded together with a time stamp of the central clock.

[0114] In a step S14, the electrode tip 111 is retracted again, for example by means of a wire feed device 141, until there is no longer a short circuit.

[0115] Steps S13 and S14 are repeated along the scanning trajectory T, whereby the number of cycles (scanning density) can also depend on the welding task, but can also be user-adjustable. The cycle of advance S13, saving the position, and retraction S14 is repeated, for example, at a frequency between 10 Hz and 500 Hz, preferably between 30 Hz and 300 Hz, particularly preferably between 75 Hz and 125 Hz. The time stamps are preferably recorded at a frequency

[0116] (e.g. 1000 Hz) which is greater both a) than the frequency of steps S13+S14 and b) than the frequency with which the information signals 73 of the robot 120 are received.

[0117] In a step S15, the acquired geometry data (i.e., the stored positions with time stamps) of the electrode tip 111 and the robot coordinates (positions and angles from the information signals 73) of the robot 120 are evaluated to obtain the desired information about the geometry and / or the position of the at least one workpiece 1, 2, for example, as described above with reference to Fig. 4. The data are combined, in particular, via the common time stamp, i.e., a common time base.

[0118] In a step S20, a specification of a welding task to be performed on the at least one workpiece 1, 2 is obtained, for example, together with the welding task, via a data interface, a data storage device, or the like. Obtaining S20 can be done wired or wirelessly.

[0119] In a step S30, based on the obtained specification and a result of the scanning program, an output signal is generated, which is designed to generate, adjust, or change at least one parameter of the welding task to be performed. This can be done, for example, as described in detail above, in particular with reference to Fig. 1 to Fig. 6. Adjusting the parameter can serve the purpose of being able to perform the welding task at all, improving the expected quality of the workpiece to be produced in the welding task, providing improved documentation (for example, information about the quality of the produced workpiece), improving the efficiency of performing the welding task (reduced speed, reduced dead time between two welding tasks, etc.), and / or the like.

[0120] In a step S40, the welding task, which includes or takes into account the at least one generated, set, or changed parameter, is performed by means of the robot 120 and the welding torch 110. In particular, the at least one workpiece 1, 2 can be welded in step S40.

[0121] Fig. 8 shows a schematic block diagram for explaining a computer program product 200 according to an embodiment of the present invention. The computer program product 200 comprises executable program code 250, which, when executed, is designed to perform the method according to an embodiment of the present invention, in particular the method described with reference to Fig. 7.

[0122] Fig. 9 shows a schematic block diagram for explaining a non-transitory computer-readable data storage medium 300 according to an embodiment of the present invention. The data storage medium 300 contains executable program code 350 which, when executed, is designed to perform the method according to an embodiment of the present invention, in particular the method described with reference to Fig. 7. In the foregoing detailed description, various features have been summarized in one or more examples to improve the stringency of the presentation. It should be understood, however, that the above description is merely illustrative and in no way restrictive in nature. It is intended to cover all alternatives, modifications, and equivalents of the various features and embodiments.Many other examples will be immediately and immediately clear to the person skilled in the art, based on his or her technical knowledge, in view of the above description.

[0123] The embodiments were chosen and described in order to best illustrate the principles underlying the invention and their practical application. This will enable those skilled in the art to optimally modify and utilize the invention and its various embodiments in relation to the intended purpose. It is further understood that units described as separate may be partially integrated with one another.

[0124] List of reference symbols

[0125] 1 workpiece

[0126] 2 Workpiece

[0127] 3 electrical connection

[0128] 71 Control signal

[0129] 72 detection signal

[0130] 73 Information signal

[0131] 74 control signals

[0132] 75 Output signal 100 Robot welding system

[0133] 110 welding torches

[0134] 111 Electrode tip 112 Consumable wire electrode 113 Additional electrode 120 Robot 121 Robot arm 131 Sensor unit

[0135] 132 computing unit

[0136] 140 welding power source

[0137] 141 Wire feed device 142 Short-circuit detector device 143 Power electronics 150 Holding device 200 Computer program 250 Program code

[0138] 300 Data storage medium 350 Program code D Feed path t Time tl, t2 Time points T Scanning trajectory

[0139] S10 ..S40

[0140] Procedural steps

Claims

Patent claims 1. A robot welding system (100), comprising: a welding torch (110) with a consumable electrode (112); a robot (120) configured to guide the welding torch (110); a welding power source (140) configured to generate a voltage between the consumable electrode (112) and a second electrode (113) connectable to at least one workpiece (1, 2); a sensor unit (131) which is configured to carry out a scanning program by means of the robot (120) and the welding torch (110), in which a geometry of the at least one workpiece (1, 2) is scanned and detected at least in sections by means of the consumable electrode (112) of the welding torch (110), wherein at least one position and / or orientation of the robot (120) is detected at the same time, wherein for detecting the geometry of the at least one workpiece (1, 2) a cycle is periodically repeated, which cycle comprises: Advancing an electrode tip (111) of the consumable electrode (112) until a short circuit between the consumable electrode (112) and the at least one workpiece (1, 2) is detected via the second electrode (113) while the latter is connected to the at least one workpiece (1, 2), storing the position of the consumable electrode (112) at the time of the detected short circuit, and withdrawing the electrode tip (111) until the short circuit is broken; and a computing unit (132) which is designed to calculate a specification of a component applied to the at least one workpiece (1, 2) to obtain a welding task to be carried out and, based on the obtained specification and on a result of the scanning program, to generate an output signal (75) which is designed to generate or set at least one parameter of the welding task to be carried out.

2. Robot welding system (100) according to claim 1, further comprising a welding power source (140), wherein the output signal (75) is configured to set a target value, a minimum value and / or a maximum value for a parameter of the welding power source (140) when performing the welding task to be performed.

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

4. Robot welding system (100) according to one of claims 1 to 3, wherein the output signal (75) is designed to set a target value, a minimum value and / or a maximum value for an angle of attack of the robot (120) when performing the welding task to be performed.

5. Robot welding system (100) according to one of claims 1 to 4, wherein the output signal (75) is designed to set a welding position and / or a welding path of the robot (120) for performing the welding task to be performed.

6. Robot welding system (100) according to one of claims 1 to 5, wherein the specification of the welding task to be performed comprises at least one requirement, and wherein the computing unit (132) is designed to determine, based on the result of the scanning program, whether the at least one requirement is met or not.

7. Robot welding system (100) according to claim 6, wherein, if the computing unit (132) comes to the conclusion that the at least one requirement is not met, the output signal (75) is generated such that the robot (120) and / or a controllable holding device (150) for at least one of the at least one workpiece (1, 2) are moved such that the requirement is met as well as possible or completely.

8. Robot welding system (100) according to claim 7, wherein the welding task comprises at least two workpieces (1, 2) and the at least one requirement comprises a requirement for relative positioning between the at least two workpieces (1, 2).

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

10. Robot welding system (100) according to claims 6 or 7 and according to claim 9, wherein the at least one requirement comprises a requirement regarding the expected quality of the welding task being performed; and wherein the output signal (75) is configured to instruct a termination of the welding task for the at least one workpiece (1, 2) if the expected quality does not correspond to a predetermined minimum quality.

11. Robot welding system (100) according to one of claims 6 to 8 or 10, wherein the at least one requirement comprises a requirement for a geometric property of at least one of the at least one workpiece (1, 2); and wherein the output signal (75) is configured to instruct an abort of the welding task for the at least one workpiece (1, 2) if the geometric property is not present.

12. Robot welding system (100) according to one of claims 1 to 11, wherein the cycle is repeated at a frequency between 10 Hz and 500 Hz, preferably between 30 Hz and 300 Hz, particularly preferably between 75 Hz and 125 Hz.

13. Robot welding system (100) according to one of claims 1 to 12, wherein the sensor unit (131) is configured to receive, in addition to position signals with the positions of the electrode tip, also information signals (73) of the robot (120).

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

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

16. A method for operating a robot welding system (100) with a robot which guides a welding torch (110) with a consumable electrode (112), comprising: 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); Carrying out (S10) a scanning program by means of the robot (120) and the welding torch (110), in which a geometry of at least one workpiece (1, 2) is scanned and detected at least in sections by means of the consumable electrode (112) of the welding torch (110), wherein at least one position and / or orientation of the robot (120) is detected at the same time, wherein for detecting the geometry of the at least one workpiece (1, 2) a cycle is periodically repeated, which cycle comprises: advancing an electrode tip (111) of the consumable electrode (112) until a short circuit between the consumable electrode (112) and the at least one workpiece (1, 2) is detected via the second electrode (113) while the latter is connected to the at least one workpiece (1, 2), Storing the position of the consumable electrode (112) at the time of the detected short circuit, and withdrawing the electrode tip (111) until the short circuit breaks; Obtaining (S20) a specification of a welding task to be performed on the at least one workpiece (1, 2); Generating (S30) an output signal (75) based on the obtained specification and on a result of the scanning program, which is designed to generate, set or change at least one parameter of the welding task to be performed.

17. The method according to claim 16, comprising performing (S40) the welding task comprising the at least one generated, set or changed parameter by means of the robot (120) and the welding torch (110).

18. The method according to 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 welding task is carried out (S40) using the selected welding process type.

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

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

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