Device for a welding control system and method for plausibility checking of force values when controlling a welding tool

Abstract

A device for a welding control system and a method for plausibility checking of a force value when controlling a welding tool are provided. The device has a determination module for determining an expected value of a physical variable which occurs in a welding process with a welding tool and which depends on a force which at least one electrode of the welding tool exerts on at least one component when establishing a welded connection, and a comparison module for comparing the expected value with an actual value of the physical variable which occurs in the welding process with the welding tool in order to plausibly check an actual value of the force detected in the welding process with the welding tool, wherein the determination module is configured to determine the expected value with a model of the welding tool.

Description

Technical Field

[0001] This invention relates to an apparatus for welding control and a method for verifying the reliability of force values ​​when controlling welding tools. Background Technology

[0002] Metal parts can be joined using welding tools. For example, welding tools are used in industrial equipment, particularly vehicle production lines. Here, metal parts, especially sheet metal, are joined by welding using these tools. In automated vehicle body frame manufacturing, welding clamps with electrode caps on the welding electrodes are used as welding tools. During resistance welding, the two welding electrodes of the welding clamp press against the components to be welded at the welding location. This forms a circuit in which a welding core is formed between the components with a specific current variation curve. In spot welding / resistance welding, the consistent quality of the weld point is crucial.

[0003] Such welding clamps are, for example, configured as electrically servo-driven welding clamps to apply force to compress the clamps and form a weld point. If the force applied to the welding clamps is too great, the clamps will be damaged. Therefore, the use of a force adjuster is advantageous in order to measure the force applied to the welding clamps so as not to cause damage to the clamps or welding tools.

[0004] The force regulator uses the measured force value, the so-called actual force, during force adjustment. This actual force is measured using a force sensor. However, the problem is that the force sensor outputs an erroneous actual force value that goes unnoticed. This can occur if the force sensor is defective or not properly manipulated.

[0005] If the sensor outputs an incorrect actual force value, then the incorrectly measured actual force will be used when adjusting and monitoring the operation of the welding tool. This results in incorrect force settings when adjusting the force of the welding tool, especially an electrically powered servo welding clamp, using an incorrect actual force value. This can lead to poor weld quality, such as open welds, excessive spatter, and even damage to the welding tool. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide an apparatus for a welding control system and a method for verifying the reliability of force values ​​when controlling welding tools, wherein the apparatus and method can solve the aforementioned problems. In particular, an apparatus for a welding control system and a method for verifying the reliability of force values ​​when controlling welding tools should be provided, wherein the generated force can be set even when the force sensor is defective or erroneously manipulated, thereby enabling easy and cost-effective maintenance of consistent weld quality and preventing damage to the welding tools without significant expense or cost.

[0007] This task is solved by an apparatus for a welding control system according to the invention. The apparatus comprises: a measurement module for measuring a predicted value of a physical parameter that occurs during welding with a welding tool and depends on a force applied to at least one component by at least one electrode of the welding tool when a weld joint is established; and a comparison module for comparing the predicted value with an actual value of the physical parameter occurring during welding with the welding tool to verify the reliability of the actual value of the force detected during welding with the welding tool, wherein the measurement module is configured to measure the predicted value using a model of the welding tool.

[0008] The aforementioned device can identify erroneously measured actual force values, or in other words, identify incorrectly measured values ​​of actual force, by evaluating the actual position values. Here, the welding tool can apply force or not apply force to the component. This final operation can be performed as part of the welding process or during commissioning or maintenance.

[0009] Therefore, even if the actual force value is measured incorrectly, it will not cause damage to the welding tool. Furthermore, it reduces the need for costly maintenance to eliminate welding equipment malfunctions. Thus, the device significantly extends the service life of the welding tool.

[0010] Furthermore, it ensures that the desired quality of the manufactured welded joint can be achieved. For example, in the case of force adjustment, it avoids weld spatter and the resulting poor weld quality in cases where the actual force value is incorrectly measured, especially if it is measured too high. Therefore, it is practically impossible to mistakenly use an excessively low actual force value.

[0011] An additional advantage is that erroneous conclusions are avoided when evaluating incorrectly measured actual forces. This can be very helpful, for example, when monitoring the welding process. Furthermore, erroneous responses from the welding control system, which might occur, for example, when adjusting the welding process, can be avoided.

[0012] In addition, the device allows for faster interruption of welding, thereby reducing waste produced by industrial equipment.

[0013] In summary, this minimizes the failure rate of welding equipment in industrial facilities. Ultimately, this increases the output of industrial equipment.

[0014] As a result, the device can control the welding tools using the welding control system, thereby ensuring the high quality of the welded joints established by the welding tools.

[0015] Other advantageous designs of the device are described in other parts of this disclosure.

[0016] The model is capable of modeling welding tools as springs and includes at least one parameter that determines the spring.

[0017] It can be considered that the parameter of the at least one spring is an equivalent spring constant, which has at least one spring constant related to the mechanical properties of the welding tool and a spring constant related to the properties of at least one component to be welded.

[0018] As a supplementary or alternative solution, it can be considered that the parameter of the at least one spring is the dead time, which delays the formation of the force used to establish the weld joint after a force is applied to the welding tool.

[0019] In a particular design, the measuring module can be configured to take into account changes in the parameters of the spring during the welding process.

[0020] The comparison module can be configured to interrupt the welding process and optionally output a fault notification to the welding control system if the difference between the expected and actual values ​​of the physical parameters is greater than a predetermined limit value.

[0021] According to one embodiment, the specific parameter is the position of at least one electrode of the welding tool, and the model includes the modeled arm bending of the welding tool.

[0022] According to another embodiment, the specific parameter is the drive current of a drive mechanism for driving at least one electrode of the welding tool.

[0023] According to another embodiment, the specific parameter is the torque of a drive mechanism for driving at least one electrode of the welding tool.

[0024] The measurement module is optionally configured to measure an expected value for at least two different intrinsic parameters, wherein the comparison module is configured to perform a comparison of the at least two different intrinsic parameters in order to verify the reliability of the actual value of the force detected during welding with welding tools.

[0025] According to another alternative, the device is configured to use predetermined weights for comparisons of the at least two different trait parameters to determine whether to initially output a warning notification as a notification only, wherein the device is configured to output a notification to interrupt the welding process only if the comparisons of the at least two different trait parameters do not perform a confidence check on the actual value of the force.

[0026] The aforementioned device can be part of a welding control system for a welding tool, the welding control system further having a force adjustment module for adjusting the change curve of the following force, which is applied to at least one component by at least one electrode of the welding tool when establishing a weld joint, wherein the welding control system is configured to interrupt the welding process if the device cannot perform a reliability check on the actual value of the force detected during welding with the welding tool.

[0027] The aforementioned welding control system may further include a setting module for evaluating the adjustment of the force adjustment module, wherein the setting module is configured to model the welding tool as a spring and set at least one regulator parameter of the force adjustment module based on at least one parameter of the determined spring.

[0028] The aforementioned device can be part of a welding apparatus, which further includes a welding tool and a welding control system, wherein the welding tool has at least one electrode for establishing a welded joint on at least one component, and wherein the welding control system is used to control the welded joint established by the welding tool, wherein the welding control system is configured to interrupt the welding process if the device cannot reliably verify the actual value of the force detected during the welding process performed with the welding tool.

[0029] Here, the welding tool can be a resistance welding tool, which is constructed as a welding clamp with two electrodes.

[0030] Furthermore, the task is solved by a method according to the invention for verifying the reliability of force values ​​when controlling a welding tool. The method is implemented by an apparatus for a welding control system and includes the following steps: measuring a predicted value of a physical parameter that occurs during welding with the welding tool and depends on a force applied to at least one component by at least one electrode of the welding tool when establishing a weld joint; and comparing the predicted value with an actual value of the physical parameter occurring during welding with the welding tool using a comparison module to verify the reliability of the actual value of the force detected during welding with the welding tool, wherein the measuring module measures the predicted value using a model of the welding tool.

[0031] The method achieves the same advantages as those mentioned earlier regarding the device.

[0032] Other possible implementations of the invention include combinations of features or implementations not explicitly mentioned in the preceding or following descriptions of the embodiments. Those skilled in the art can also add individual aspects as improvements or supplements to the corresponding basic form of the invention. Attached Figure Description

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Wherein it is shown that:

[0034] Figure 1 A greatly simplified schematic diagram of an industrial apparatus having a welding device according to a first embodiment is shown, the welding device using a welding control system for controlling welding tools and a device for verifying the reliability of actual force values ​​on the welding tools;

[0035] Figure 2 A cross-sectional view of the welding electrode of the welding tool according to the first embodiment in operation is shown when the welding tool is not yet ready to perform welding.

[0036] Figure 3 A cross-sectional view of the welding electrode of the welding tool according to the first embodiment in operation is shown when the welding tool is ready to perform welding and establish a welded joint.

[0037] Figure 4 A diagram illustrating the equivalent model of a C-clamp as three springs connected in series is shown.

[0038] Figure 5 It is shown that in a clamping closing motion V ACT A graph showing the time-varying force of a specific instance of a step input velocity;

[0039] Figure 6A simplified view of an adjustment circuit for adjusting force according to a first embodiment is shown, wherein the force is applied to the welding position by a welding tool during a welding or maintenance process;

[0040] Figure 7 A flowchart of a method is shown, which is implemented by an apparatus according to a first embodiment for verifying the reliability of actual force values ​​on a welding tool;

[0041] Figure 8 A diagram of an apparatus for verifying the reliability of actual force values ​​on welding tools, according to a second embodiment, is shown; and

[0042] Figure 9 A diagram of an apparatus for verifying the reliability of actual force values ​​on a welding tool, according to a third embodiment, is shown.

[0043] In the accompanying drawings, unless otherwise specified, the same or functionally equivalent elements are given the same reference numerals. Detailed Implementation

[0044] Figure 1 An industrial apparatus 1 is shown, comprising a welding device 2 for welding at least one metal component 5, 6. Here, the at least one metal component 5, 6 is connected by at least one welded joint 7. The at least one welded joint 7 is, for example, a weld point and / or a weld seam. Here, only two edges of two metal components 5, 6, or one of said components 5, 6, can be connected to each other. Weld spatter 8 may undesirably occur during welding.

[0045] The industrial equipment 1 is, for example, a production line for vehicles, furniture, buildings, etc., in which metal components 5 and 6 are welded. For this purpose, the welding equipment 2 has a welding control system 10, a first device 20 for guiding a welding tool 21 with two welding electrodes 22 and 23, which is used as a resistance welding tool, a detection mechanism 30 for providing data 35, an operating mechanism 40, and a second device 50. The first device 20 is controlled by the control mechanism 25. Furthermore, communication lines 41 to 45 are provided, which can in particular be implemented as a bus system. The operating mechanism 40 can output notifications 48, especially status notifications and / or fault notifications and / or other information. The second device 50 is used for reliability verification of at least a portion of the data 35.

[0046] The device 20 is, in particular, a robot. The manipulation mechanism 40 can be implemented, for example, as a keyboard and / or mouse, a laptop computer, a touch-sensitive or touch-insensitive screen, or a combination thereof.

[0047] according to Figure 1The welding tool 21 is a welding clamp with at least one electrode 22, 23. In particular, the welding tool 21 is an electrically servo-driven welding clamp. Figure 1 In one example, the welding clamp is constructed as a C-type clamp. It is feasible that one clamp arm—with an electrode 22 disposed at its end, for example—is a movable clamp arm, while the other clamp arm—with an electrode 23 disposed at its end, for example—is a fixed clamp arm. A detection mechanism 30, particularly a force sensor, can be mounted on the fixed clamp arm. Of course, other variations for implementing the welding tool 21 and / or for arranging the detection mechanism 30 on the welding tool 21 are also feasible.

[0048] The welding control system 10 is used to control the welding tool 21. Therefore, the welding control system 10 is connected to the welding tool 21 or its electrical components via a communication line 41. Furthermore, the welding control system 10 is connected to the operating mechanism 40 via a communication line 42. Additionally, the welding control system 10 receives data 35 detected by the detection mechanism 30 during the operation of the welding tool 21 via the communication line 41. For this purpose, the detection mechanism 30 has at least one sensor for detecting physical parameters that are important during welding and are referred to below as data 35. Such physical parameters or data 35 include, in particular, the holding force and / or clamping force Fs used to hold the welding tool 21 on at least one component 5, 6 and / or to press the electrodes 22, 23 onto at least one component 5, 6 during the welding process for establishing the weld joint 7.

[0049] Therefore, the detection mechanism 30 particularly includes at least one force sensor. As a supplementary or alternative, the detection mechanism 30 can particularly include at least one position sensor, such as a rotary encoder and / or a gyroscope sensor and / or a motion sensor. As a supplementary option, the detection mechanism 30 can include at least one sensor for detecting at least one electrical parameter during the welding process.

[0050] The welding control system 10 has a setting module 11, a force adjustment module 12, and a memory module 13. Optionally, the setting module 11 is used to set the regulator parameters of the force adjustment module 12, which can optionally be done by evaluating data 35, which is stored in the memory module 13.

[0051] To control the welding process performed with welding tool 21, the welding control system 10, more precisely in its memory module 13, stores internal basic parameters or ratings 131, which can be input by the user either at the factory or later via the operating mechanism 40. These internal basic parameters or ratings 131 can be parameters of the welding tool 21. Furthermore, these internal basic parameters or ratings 131 can be parameters of the welding control system 10 used to control the welding tool 21. Specifically, these internal basic parameters or ratings 131 are the phase angle of the welding current Is and / or the resistance R and / or holding force and / or clamping force Fs of the welding tool 21 and / or at least one limit value—the limit value used to determine whether a notification 48 should be output on the operating mechanism 40—especially a status notification and / or fault notification and / or other information. The welding current Is is transmitted through... Figure 1 A welding transformer (not shown) is fed to welding tool 21. This should be referenced. Figure 2 Provide a detailed description.

[0052] All internal basic parameters or ratings 131 can be stored as time-dependent parameters or rating-time variation curves of the corresponding rated parameters. Therefore, in particular, it is possible to store the welding current Is(t) and / or resistance R(t) and / or holding force and / or clamping force Fs(t) of the welding tool 21. Here, it is possible to store continuous time variation curves or intermittently determined time variation curves.

[0053] The detection mechanism 30 outputs at least a portion of its data 35 to the second device 50. The data 35 specifically includes the predetermined positions L of the electrodes 22 and 23. G Or at least the position of electrode 22 on the movable clamp arm and / or the actual position L of electrodes 22 and 23 changing over time. ACT Or at least the actual position L of electrode 22 on the movable clamp arm that changes over time. ACT The actual force F detected during the welding process, including the holding force and / or clamping force Fs. S_ACT Subsequently, the device 50 is able to transmit data 35 to the welding control system 10.

[0054] The second device 50 has a measurement module 51 and a comparison module 52. The measurement module 51 is used to measure, in particular to calculate, the expected actual position L of electrodes 22 and 23. E Here, the device 50 uses a model 511 of the welding tool 21 to determine the modeled position of the welding tool 21, especially the bending angle A of the arm of the welding tool 21. BThe comparison module 52 is used to compare the measurement results with the actual positions L of the electrodes 22 and 23 of the welding tool 21. ACT The actual position value is compared. Based on the comparison result of the comparison module 52, the comparison module 52 controls the welding control system 10 to interrupt or not interrupt the welding process. Furthermore, the comparison module 52 can control the operating mechanism 40 based on the comparison result to output or not output a fault notification as notification 48. This will be described in more detail below.

[0055] When the welding tool 21 is guided by the arm 24 of the device 20, the device 20 is controlled by its control mechanism 25. For this purpose, the control mechanism 25 is connected to the welding control system 10 via a communication line 43. Alternatively, the control mechanism 25 is connected to the operating mechanism 40 via a communication line 44. The opening or closing of the welding tool 21 is achieved by driving the drive mechanism 26.

[0056] As a supplementary or alternative solution, the control mechanism 25 is directly connected to the electrical components of the detection mechanism 30 and / or welding tool 21 via communication line 45. If there is no redundancy requirement, the communication line 43 can be omitted.

[0057] Through communication lines 42 to 45, relevant data concerning welding performed with the welding tool 21 can be exchanged between the welding control system 10 and the device 20, more precisely, the control mechanism 25 and / or the operating mechanism 40. Furthermore, the control mechanism 25 can store internal basic parameters or ratings 251, which are used to control the welding tool 21, particularly for positioning it in space and thus on components 5 and 6.

[0058] Figure 2 The construction of electrodes 22 and 23 of the welding tool 21 in this embodiment is shown in more detail. Electrode 22 is constructed as an electrode rod with an electrode cap 220 at one end. The electrode cap 220 is disposed on the end of electrode 22 facing member 5. The electrode cap 220 has an axis 221, which is the same as the axis of electrode 22. Furthermore, electrode 23 is constructed as an electrode rod with an electrode cap 230. The electrode cap 230 is disposed on the end of electrode 23 facing member 6. The electrode cap 230 has an axis 231, which is the same as the axis of electrode 23.

[0059] exist Figure 2In this example, electrode 22 is mounted on a movable jaw arm of welding tool 21. Electrode 23 is mounted on a fixed jaw arm of welding tool 21. In this example, the jaw arm of welding tool 21 is open. Thus, axes 221 and 231 are transverse to each other. At least one component 5 or 6 has a thickness D between electrodes 22 and 23, more specifically between their electrode caps 220 and 230.

[0060] Figure 2 The operating state exists when the welding tool 21 is positioned on the components 5 and 6 at the location to be welded. In this operating state, the welding tool 21 is not yet ready for welding. Therefore, the welding current Is has not yet been supplied by the welding transformer 27.

[0061] The welding tool 21 can be processed using a cleaning mechanism 60, shown schematically, such that contaminated portions of one of the electrode caps 220, 230 can be cut or milled when necessary. The cleaning mechanism 60 can be configured as a milling and / or cutting mechanism or a replacement mechanism. Therefore, the electrode caps 220, 230 are wear objects.

[0062] like Figure 3 As shown, the electrodes 22 and 23 are arranged on at least one component 5 and 6 on both sides of the position to be welded during the operation of the welding tool 21, and are placed on at least one component 5 and 6 by means of holding force and / or clamping force Fs. Thus, the axes 221 and 231 are ideally arranged in a line.

[0063] In other words, in Figure 3 In operation, the two electrodes 22 and 23 clamp the components 5 and 6 with a force Fs. The electrodes 22 and 23 are fed toward the at least one component 5 and 6 to varying degrees depending on the number of milling and / or cutting processes performed on the electrode caps 220 and 230, in order to obtain the desired force Fs.

[0064] In this state where the welding tool 21 is closed and a force Fs has been generated, arm bending A occurs. B The clamp arm of the welding tool 21 behaves like a spring, as will be described in detail below.

[0065] The welding current Is is then delivered to the electrodes 22 and 23 for a predetermined duration T and with predetermined characteristics by means of the welding transformer 27. For this purpose, a current Is with a defined current variation curve is delivered, especially when at least partially regulated. This generates heat in at least one component 5 or 6, thereby forming a welding core, which later forms the welded joint 7.

[0066] As mentioned above, during the operation of the welding tool 21, data 35 is detected by the detection mechanism 30. To verify the reliability of at least a portion of the data 35, the device 50 takes the following actions.

[0067] The device 50 uses a model 511 of the welding tool 21 to determine the modeled position of the welding tool 21, particularly the bending angle of the arm of the welding tool 21. B Here, model 511 assumes the welding tool 21 to be a spring. Therefore, as referenced... Figure 4 As explained in more detail, in model 511, an equivalent spring constant k_E is assigned to the welding tool 21.

[0068] Therefore, in model 511, the actual force F of the holding force and / or clamping force Fs during the welding process is derived. S_ACT China as

[0069] A B =F S_ACT / k_E (1)

[0070] To calculate the arm bending A of the welding tool 21 during the welding process and / or during the progress of the welding process. B .

[0071] According to equation (1), the arm of the welding tool 21 bends by A. B The actual force F depends on the holding force Fs and / or the clamping force Fs. S_ACT That is, the actual force F of the holding force and / or clamping force Fs. S_ACT The larger the arm bends, the greater the bending A. B The larger the force, the greater the actual force F when the clamp arm of the welding tool 21 is opened. S_ACT =0. Therefore, in this state, the arm bending is also A. B =0.

[0072] During the welding process, the actual force F S_ACT The force increases due to the thermal expansion of the material of at least one component 5 or 6 after the current Is is introduced. Conversely, the actual force F S_ACT The force decreases after at least one of the components 5 and 6 is melted due to a welded connection 7. If weld spatter 8 occurs, then the actual force F... S_ACT Similarly, it decreases. Therefore, during the welding process, the actual force F of the welding tool 21 decreases. S_ACT And thus, arm A bends B It also changes over time.

[0073] Figure 4An equivalent model 210 of the welding tool 21 is shown, which is based on model 511 and used by the device 50. The equivalent model 210 models the welding tool 21 as a spring, more specifically as a series connection of springs 211, 212, and 213. Here, spring 213 is arranged between springs 211 and 212. The total spring length, and thus the welding clamp 21 modeled, is determined by the equivalent spring constant k_E and the dead time Tt. The dead time Tt is... Figure 5 As shown in the diagram, Figure 5 V in the clamp movement ACT The actual force F of the holding force and / or clamping force Fs is shown as the actual input step speed with respect to time t. S_ACT .exist Figure 5 In the example, the actual force F S_ACT It is expressed in physical units N and time t is expressed in physical units ms.

[0074] Spring 211 represents the mechanical characteristic of the first clamping arm of welding tool 21, which is movable. Spring 212 represents the mechanical characteristic of the second clamping arm of welding tool 21, which is fixed. Spring 213 represents the mechanical characteristic of at least one component 5, 6.

[0075] Spring 211 has a spring constant k_F1. Spring 212 has a spring constant k_F2. Spring 213 has a spring constant k_F3. By connecting them in series, according to equation (2):

[0076] 1 / k_E=1 / k_F1+1 / k_F2+1 / k_F3 (2)

[0077] The total spring constant or equivalent spring constant k_E is obtained.

[0078] Therefore, the total spring constant or equivalent spring constant k_E is always less than the individual spring constants k_F1, k_F2, and k_F3. Thus, the combination of springs 211 to 213 produces a softer total spring. The force F varies with time t. S (t) In the series connection of springs 211 to 213, each spring 211 to 213 acts in the same amount.

[0079] The device 50 can be operated, for example, by the following equation (3), when the welding clamp 2 and / or welding tool 21 are put into operation:

[0080] k_E=△F S_ACT / △s ACT =△F S_ACT / V ACT *△t (3)

[0081] To calculate the equivalent spring constant k_E.

[0082] Here, ΔF S_ACT When at a predetermined constant speed V ACT The difference in force detected when at least one clamp arm of the welding tool 21 is driven for a predetermined duration Δt. Here, the clamp arm, i.e., springs 211, 212, and therefore spring 213, is compressed by a stroke Δs. ACT .

[0083] If the equivalent spring constant k_E and / or the dead time Tt are measured, especially when using a force gauge, the measured equivalent spring constant k_E and / or the measured dead time Tt are stored in data 35 in model 511 and, if necessary, additionally in memory module 13. Therefore, in subsequent welding processes using welding tool 21, the device 50 can utilize the equivalent spring constant k_E and / or the dead time Tt.

[0084] As an alternative, it is feasible not to use it as an actual force F. S_ACT Instead, it is used as a polynomial of order 1 to 3 in the following equation (4):

[0085] A B =a*F S_ACT 3 +b*F S_ACT 2 +c**F S_ACT +d (4)

[0086] To measure the arm bending A B .

[0087] The identification of coefficients a, b, c, and d is performed using an approximation method, which involves bending the arm A across the entire range of use of the welding tool 21 after the previous measurement. B The relative deviation between the calculated and measured values ​​is minimized. The least squares method is used here. The determination of the equivalent spring constant k_E is a special case of this method, where the coefficients a, b, and d are set to zero. If c is the equivalent spring constant k_E, then it is represented by equation (5):

[0088] AB = c * F S_ACT =k_E*F S_ACT (5)

[0089] To get to the conclusion.

[0090] When the welding tool 21 is closed, there are no components 5 and 6 with thickness D arranged between the electrodes 22 and 23, and the electrodes 22 and 23 and therefore their electrode caps 220 and 230 are arranged in a predetermined position L. GIn the middle. The position L G This refers to the actual position when the welding tool 21 is closed.

[0091] Therefore, the device 50 for verifying the reliability of data 35 takes the following actions. Especially during the welding process, the measurement module 5 acts as…

[0092] L E =L G -D+A B (6)

[0093] To determine the expected position L of electrodes 22 and 23 E .

[0094] The comparison module 52 then uses the electrodes 22 and 23 at their current or actual positions L during the welding process. ACT As the current or actual position L of electrodes 22 and 23 during the welding process ACT The expected position L determined by the measurement module 51 E The difference constituted as

[0095] L DIFF =L ACT -L E (7)

[0096] To calculate the position difference L DIFF .

[0097] If the position difference L DIFF Too big, that is, L DIFF If the value exceeds a predetermined limit value stored in the internal basic parameters or rated values ​​131, then the comparison module 52 controls the welding control system 10 to interrupt the welding process. Additionally, the comparison module 52 may optionally control the operating mechanism 40 to output a fault notification as a notification 48. As a result, defective welded joints 7 are not established.

[0098] Figure 6 The structure of the adjustment circuit formed by the force adjustment module 12 for maintaining the force and / or clamping force Fs during the welding process using the welding tool 21 is shown.

[0099] The regulating object (Regelstrecke) 122 is an integral path (I-path). Furthermore, a dead time Tt exists, which acts on the welding tool 21 between the introduction and application of force Fs. Therefore, in the regulating object 122, a time delay occurs in the form of a dead time Tt when force Fs(t) is formed, as previously referred to. Figure 5 As described.

[0100] A welded joint is established during the welding process. Therefore, Figure 6 The force adjustment module 12 and its interconnection with the setting module 11, memory module 13, detection mechanism 30, and device 50 are shown more precisely. Furthermore, the memory module 13 can store data 35, particularly the actual force F detected by the detection mechanism 30 during the welding process, representing the holding force and / or clamping force Fs. S_ACT and / or the actual position L ACT Furthermore, the memory module 13 stores basic parameters and rated parameters 131, particularly the time-dependent rated force Fs(t) for holding force and / or clamping force, and the position difference L. DIFF The limit value. In addition, the setting parameters 132 of the setting module 11 can be stored in the memory module 13.

[0101] The force adjustment module 12 has an adjuster 121 and an adjustable object 122, wherein the adjuster 121 has specially set adjuster parameters 120. As explained in more detail below, the adjuster 121 in this example is a PD adjuster. The PD adjuster is a combination of a proportional adjuster and a derivative adjuster. The adjustable object 112 is a part of the adjustment loop formed by the force adjustment module 12, which contains the physical parameters to be adjusted, namely, the holding force and / or clamping force Fs. Alternatively, other physical parameters, especially the actual position L, can be adjusted additionally. ACT .

[0102] The force F currently in effect S_ACT The force F is detected by the testing agency 30, or more precisely, by at least one of its force sensors. S_ACT The detection results are then sent to the PD regulator 121, such as... Figure 6 As shown in the image.

[0103] The PD regulator 121 therefore acts on the rated parameters, namely the rated force Fs(t) of the holding force and / or clamping force Fs and the detected actual force Fs of the holding force and / or clamping force Fs. S_ACT The difference. Therefore, a force F is generated. S_ACT The force acts on electrodes 22 and 23 during the welding process and thus on at least one component 5 and 6.

[0104] The setting module 11 can optionally set the regulator parameter 120. Here, the regulator parameter 120 can be optimized to achieve the desired weld quality using the currently used welding tool 21. Alternatively, the setting module 11 can further adjust the set regulator parameter 120 during continuous operation of the welding equipment. For example, this can be achieved by adjusting the adjustment deviation F.S1 =F S (t)-F S_ACT Analysis.

[0105] In a way to measure actual force F S_ACT In the method for verifying the credibility of a value, the device 50 takes the following actions. The method in... Figure 7 As shown in the image.

[0106] Figure 7 Used for actual force F S_ACT The value is verified for reliability and used to control the welding tool 21, for example, during the welding process to establish a welded joint 7. During the welding process, the welding current I is normally set. S Loading. However, as an alternative, Figure 7 The method can be performed during maintenance, that is, without applying welding current Is.

[0107] In step S1, the measuring module 51 measures the expected position L of the electrodes 22 and 23 of the welding tool 21 as described above. E The measuring module 51 will measure the position L. E The data is then transmitted to comparison module 52. The process then proceeds to step S2.

[0108] In step S2, the comparison module 52 determines the position difference L. DIFF Whether the numerical value is greater than a predetermined limit value. If the position difference L DIFF If the numerical value is less than a predetermined limit, the process proceeds to step S3. Otherwise, that is, if the position difference L... DIFF If the value is greater than a predetermined limit, the process proceeds to step S6.

[0109] In step S3, the welding process is carried out. Therefore, as described above, under the control of the welding control system 10, a welded connection 7 is established on at least one component 5, 6 using welding tool 21. The process then proceeds to step S4.

[0110] In step S4, it is checked whether the welded connection 7 established in step S3 meets the pre-defined quality requirements. Then the process proceeds to step S5.

[0111] In step S5, the inspection result of step S4 is stored in memory module 13. Alternatively or as a supplement, the inspection result of step S4 is output as a corresponding notification 48 at operating mechanism 40. This output can be particularly performed optically and / or acoustically. The method then terminates.

[0112] In step S6, that is, if the position difference L DIFF If the value exceeds a predetermined limit, the welding process is interrupted or not performed. Alternatively, a corresponding notification 48 can be output at the operating mechanism 40. This output can be, in particular, optical and / or acoustic. The method then terminates.

[0113] Figure 7 The previously described method can be implemented either before each welding process or before each maintenance process, such as before a cleaning process performed using the cleaning device 60. Very commonly, the reliability verification of the force value Fs can be performed each time the welding tool 21 is closed, wherein the actual force F is measured. S_ACT That is to say, measurements are taken, for example, before the welding process (using welding current) or before the maintenance process (without welding current), such as before milling, setting the stroke, etc.

[0114] In the preceding description, model 511 assumed a constant spring constant k_F1 for the fixed clamp arm for the corresponding welding tool 21. However, unlike the preceding description, the spring constant k_F1 of the fixed clamp arm may vary for different welding tools 21 during the service life of the welding tool 21 due to mechanical wear. Furthermore, the spring constant k_F1 may change during welding due to heat generated by the welding tool 21. Therefore, the spring constant k_F1 can change over time as needed. This change can occur during the service life of the welding tool 21 and / or during the welding process, especially during the progress of the welding process.

[0115] Furthermore, model 511 assumes that the spring constant k_F2 of the movable clamping arm is constant for the corresponding welding tool 21. However, for different welding tools 21, the spring constant k_F2 of the movable clamping arm may change due to mechanical wear during the service life of the welding tool 21. Additionally, the spring constant k_F2 may change during welding due to heat generated by the welding tool 21. Therefore, the spring constant k_F2 can change over time as needed. This change can occur during the service life of the welding tool 21 and / or during the welding process, especially during the progress of the welding process.

[0116] The model 511 takes into account that the spring constant k_F3 of at least one component 5, 6 changes with time t during the time interval between cleaning processes performed by the cleaning mechanism 60. When welding is performed, the spring constant k_F3 changes, for example, due to thermal expansion and due to the melting of components 5, 6.

[0117] Because the force reliability check is performed before the welding time begins, these disturbances / changes in the equivalent spring constant have no effect in this regard.

[0118] Furthermore, the setting module 11 can change the regulator parameter 120 according to the changed equivalent spring constant k_E.

[0119] According to a modified embodiment of this invention, as described above, the setting module 11 does not adjust the deviation F. S1 An evaluation is conducted. In other words, the welding control system 10, particularly its setting module 11, is tested for the actual force F. S_ACT The spectrum is evaluated. Here, the welding control system 10, especially its setting module 11, uses FFT analysis (FFT = Fast Fourier Transform). If the actual force F S_ACT If a maximum value can be identified in the spectrum, it indicates oscillation. Therefore, the setting module 11 evaluates the maximum value as the presence of force oscillation. In this way, force oscillation can also be identified and avoided.

[0120] Figure 8 A portion of the apparatus 50A and welding tool 21, which can be used in a second embodiment, is shown. The welding tool 21 has a drive mechanism 26 for driving the welding tool 21 to change the arm bending A. B A drive current In is supplied to the drive mechanism 26, causing the drive mechanism 26 to be driven at a predetermined rotational speed n.

[0121] Unlike the device 50 according to the foregoing embodiment, the device 50A is configured to additionally convert the actual drive current In_ ACT It is included in the credibility verification check. Therefore, model 511 is used as the actual force F. S_ACT and torque constant k m The function to use the reference drive current or the expected drive current I E .

[0122] Therefore, during the welding process, the measuring module 51 serves as...

[0123] I E =(F S_ACT *kv) / (2π*k m (8)

[0124] To determine the expected drive current I E .

[0125] Then, the comparison module 52 uses the current In or the actual drive current In_ of the drive mechanism 26 during the welding process according to equation (9).ACT As

[0126] I DIFF =In_ ACT -I E (9)

[0127] To calculate the current difference I DIFF .

[0128] Therefore, the calculation is based on the current or actual drive current In_ during the welding process. ACT The expected drive current I measured by the measurement module 51 E The difference in composition.

[0129] If the current difference I DIFF Too large, that is to say, if I DIFF If the value exceeds a predetermined limit, the comparison module 52 controls the welding control system 10 to interrupt the welding process. Alternatively, the comparison module 52 may further control the operating mechanism 40 to output a fault notification as a notification 48. As a result, defective welded joints 7 are not established. The predetermined limit value can be stored in the memory module 13 as an internal basic parameter or rated value 131.

[0130] The position L_ of electrodes 22 and 23 is determined by the measuring module 51. ACT The actual driving current In_ of the drive mechanism 26 during the welding process was measured. ACT The combination of these factors enables better and / or more reliable identification and response to erroneous force measurements of force Fs.

[0131] According to a modification of this embodiment, the device 50A also uses the parameters of the drive mechanism 26 to determine the actual position L_ of the electrodes 22 and 23 during the welding process. ACT Especially for the electrically servo-driven welding clamp 21, which serves as the welding tool, a rotary encoder can be used to detect the actual positions L_ of electrodes 22 and 23. ACT The rotary encoder provides the detection mechanism 30 with actual position values, which correspond to the positions of the movable clamping arms, that is, the positions of the electrodes 22 in this example. Therefore, a separate position sensor is not required.

[0132] Figure 9 A portion of the device 50B and welding tool 21 is shown, the welding tool being usable in a third embodiment. Unlike one of the devices 50, 50A according to the foregoing embodiments, device 50B is configured to additionally transfer the actual torque Mn_ ACT This is included in the credibility check. Therefore, model 511 is used as the actual force F.S_ACT The function uses the reference torque or the desired torque M E .

[0133] Therefore, during the welding process, the measuring module 51 is controlled by the load torque M. L and acceleration torque M B Or it can be determined by the actual force F with a feed constant kv. S _ ACT To determine the expected torque M E The feed constant kv is determined by the actual feed rate V of at least one electrode 22, 23 of the welding clamp 21. ACT and the actual rotational speed n of the drive mechanism 26 ACT As

[0134] This can be calculated.

[0135] Here, according to equation (10), the total moment of inertia J of the welding tool 21 is... ges and the actual rotational speed n of the drive mechanism 26 ACT The actual rotational speed n of the drive mechanism 26 at time t=0 ACT,0 The accelerating torque M is derived from the derivative of the difference between the initial values ​​and the time t. B .

[0136] The comparison module 52 then uses the current torque or actual torque Mn_ of the drive mechanism 26 during the welding process. ACT Based on equation (11) as

[0137] M DIFF =Mn_ ACT -M E (11)

[0138] To calculate the torque difference M DIFF .

[0139] In other words, the calculation is based on the current torque or actual torque Mn_ during the welding process. ACT The expected torque M measured by the measurement module 51 E The difference in composition.

[0140] If the torque difference M DIFF Too large, that is to say, if M DIFF If the value exceeds a predetermined limit, the comparison module 52 controls the welding control system 10 to interrupt the welding process. Alternatively, the comparison module 52 may further control the operating mechanism 40 to output a fault notification as a notification 48. As a result, defective welded joints 7 are not established. The predetermined limit value can be stored in the memory module 13 as an internal basic parameter or rated value 131.

[0141] The position L_ of electrodes 22 and 23 is determined by the measuring module 51. ACT The actual torque Mn of the drive mechanism 26 during the welding process was measured. ACT The combination of these factors enables better and / or more reliable identification and response to erroneous force measurements of force Fs.

[0142] According to the fourth embodiment, the welding tool 21 is configured as an X-shaped clamp. The electrodes 22 and 23 are preferably configured as water-cooled electrode rods in the aforementioned welding clamp.

[0143] All previously described design options for the welding equipment 2, welding control system 10, devices 50, 50A, 50B, setting module 11, force adjustment module 12, and method can be used individually or in all feasible combinations. In particular, all features and / or functions of the foregoing embodiments can be arbitrarily combined. Furthermore, the following modifications are particularly conceivable.

[0144] The components shown in the accompanying drawings are schematically illustrated, and their exact form may differ from that shown in the accompanying drawings, provided that their previously described functions are ensured.

[0145] It is conceivable that at least one of the devices 50, 50A, and 50B is not configured as a separate device 50, 50A, or 50B, but rather as part of the welding control system 10.

[0146] Of course, it is feasible to determine a predetermined weight in the second and / or third embodiments, which can be used as notification 48 to output a fault notification. That is, for example, if the allowable current difference I is exceeded... DIFF However, it did not exceed the allowable positional difference L. DIFF Then the device 50A will first only output a warning notification and only if the difference exceeds the two I DIFF L DIFF The welding process is only interrupted at certain times. Furthermore, this also applies to combinations of the second and third embodiments. Therefore, at least one of the devices 50, 50A, and 50B can be constructed for verifying the force Fs(t) and F only when there is no confidence in comparing at least two different physical parameters. S_ACT Only when the actual value is reached will a notification be output to interrupt the welding process.

[0147] The welding control system 10 enables the parameterization of simulated regulators. Regulator parameterization can be performed for the force regulator and / or speed regulator. Specifically, the force regulation module 12 can output at least one speed rating n_S to the drive mechanism 26 of the welding tool 21, so that the speed regulator of the drive mechanism 26 can adjust the drive of the welding tool 21 to apply a force F. S (t), F S_ACT As an alternative, adjusting other physical parameters is also feasible.

[0148] The simulation of the regulator parameterization can be supported using MATLAB Simulink.

[0149] The welding tool 21 is not necessarily implemented as a welding clamp, but can have only one welding electrode 22 or 23, etc.

[0150] As an alternative, force F can be applied on both sides, that is, not only at electrode 22 or only at electrode 23, but through both electrodes 22 and 23. S The corresponding import.

[0151] Alternatively, it is feasible to use other regulators 121 as PD regulators. In this case, the other regulator parameters of the regulator 121 are changed to avoid force F. S Oscillations. Here, as an alternative, it is feasible to connect multiple regulators 121 sequentially. If, for example, a two-point regulator is used instead of a PD regulator, a solution with less dynamics and less advantageous regulation technology is provided compared to the previously described solution using a PD regulator. Here, the appropriate parameters for the two-point regulator must then be matched to avoid oscillations.

Claims

1. An apparatus (50, 50A, 50B) for a welding control system (10), comprising: a measuring module (51) for measuring a predicted value (L) of a physical parameter. E I E M E The physical parameters mentioned above arise during the welding process using the welding tool (21) and depend on the force (F). S (t), F S_ACT At least one electrode (22, 23) of the welding tool (21) applies the force (F) when establishing the weld joint (7). S (t), F S_ACT The expected value (L) is applied to at least one component (5, 6); and a comparison module (52) is used to compare the expected value (L) with the expected value (L). E I E M E ) and the actual value of the physical parameters that occur during the welding process using the welding tool (21) (L) ACT In_ ACT Mn_ ACT ) to compare in order to compare the force (F) detected during welding with the welding tool (21). S (t), F S_ACT The actual value of ) is verified for reliability, wherein the measuring module (51) is configured to measure the expected value (L) using a model (511) of the welding tool (21). E I E M E The physical parameter is the position of at least one electrode (22, 23) of the welding tool (21), and the model (511) includes the modeled arm bending (A) of the welding tool (21). B ), or wherein the physical parameter is the driving current (In) of the driving mechanism (26) for driving at least one electrode (22, 23) of the welding tool (21), or wherein the physical parameter is the torque (M) of the driving mechanism (26) for driving at least one electrode (22, 23) of the welding tool (21).

2. The apparatus (50, 50A, 50B) according to claim 1, wherein the model (511) models the welding tool (21) as a spring (211, 212, 213) and has at least one parameter (k_E, Tt) that determines the spring (211, 212, 213).

3. The apparatus (50, 50A, 50B) according to claim 2, wherein the parameter (k_E, Tt) of the at least one determining spring (211, 212, 213) is an equivalent spring constant (k_E), the equivalent spring constant (k_E) having at least one spring constant (k_F1, kF2) with respect to the mechanical properties of the welding tool (21) and a spring constant (k_F3) with respect to the properties of at least one component (5, 6) to be welded.

4. The apparatus (50, 50A, 50B) according to claim 2, wherein the parameter (k_E, Tt) of the at least one determining spring (211, 212, 213) is the dead time (Tt), when a force (F) is applied to the welding tool (21). S (t), F S_ACT The dead time (Tt) delay is used to establish the force formation for the welded connection (7).

5. The apparatus (50, 50A, 50B) according to any one of claims 2 to 4, wherein the measuring module (51) is configured to take into account changes in at least one parameter (k_E, Tt) of the spring (211, 212, 213) during the welding process.

6. The apparatus (50, 50A, 50B) according to any one of claims 2 to 4, wherein the comparison module (52) is configured to, if the expected value (L) of the physical parameter is obtained, E I E M E ) and actual value (L) ACT In_ ACT Mn_ ACT If the difference between the two values ​​is greater than a predetermined limit, the welding process is interrupted.

7. The apparatus (50, 50A, 50B) according to any one of claims 2 to 4, wherein the comparison module (52) is configured to, if the expected value (L) of the physical parameter is obtained, E I E M E ) and actual value (L) ACT In_ ACT Mn_ ACT If the difference between the two values ​​is greater than a predetermined limit, the welding process is interrupted and a fault notification (48) is output to the welding control system (10).

8. The apparatus (50A, 50B) according to any one of claims 2 to 4, wherein the measuring module (51) is configured to measure the expected value (L) for at least two different physical parameters respectively. E I E M E ), and wherein the comparison module (52) is configured to compare at least two different physical parameters in order to compare the force (F) detected during welding with the welding tool (21). S (t), F S_ACT The actual value is used to verify its credibility.

9. The apparatus (50, 50A, 50B) according to claim 8, wherein the apparatus (50, 50A, 50B) is configured to use the predetermined weighting for the comparison of at least two different physical parameters to determine whether to initially output only a warning notification as a notification (48), and wherein the apparatus (50, 50A, 50B) is configured to only output a warning notification as a notification (48) if the comparison of at least two different physical parameters does not affect the force (F). S (t), F S_ACT Only when the actual value of ) is verified for reliability will a notification to interrupt the welding process be output (48).

10. A welding control system (10) for a welding tool (21), comprising: a system for adjusting force (Fs(t), F... S_ACT The force adjustment module (12) of the change curve of the welding tool (21) will adjust the force (Fs(t), F) when establishing the weld connection (7) by at least one electrode (22, 23) of the welding tool (21). S_ACT The welding control system (10) is configured to apply the force (F) to at least one component (5, 6) if the device (50, 50A, 50B) cannot apply the force (F) detected during welding with the welding tool (21). S (t), F S_ACT If the actual value is verified for reliability, the welding process is interrupted.

11. The welding control system (10) according to claim 10, further comprising a setting module (11) for evaluating the adjustment of the force adjustment module (12), wherein the setting module (11) is configured to model the welding tool (21) as a spring (211, 212, 213) and set at least one regulator parameter (120) of the force adjustment module (12) based on at least one parameter (k_E, Tt) of the spring (211, 212, 213).

12. A welding apparatus (2), comprising: a welding tool (21) having at least one electrode (22, 23) for establishing a weld joint (7) on at least one component (5, 6); a welding control system (10) for controlling the establishment of the weld joint (7) using the welding tool (21); and a device (50, 50A, 50B) according to any one of claims 1 to 9, wherein the welding control system (10) is configured to, if the device (50, 50A, 50B) fails to control the force (F) detected during the welding process using the welding tool (21), S (t), F S_ACT If the actual value is verified for reliability, the welding process is interrupted.

13. The welding apparatus (2) according to claim 12, wherein the welding tool (21) is a resistance welding tool, the resistance welding tool being configured as a welding clamp having two electrodes (22, 23).

14. A method for verifying the reliability of a force value when controlling a welding tool (21), wherein the method is implemented by means of a device (50, 50A, 50B) for a welding control system (10) and comprises the following steps: measuring (S1) the expected value (L) of a physical parameter using a measuring module (51). E I E M E The physical parameters mentioned above arise during the welding process using the welding tool (21) and depend on the force (F). S (t), F S_ACT At least one electrode (22, 23) of the welding tool (21) applies the force (F) when establishing the weld joint (7). S (t), F S_ACT The expected value (L) is applied to at least one component (5, 6); and the comparison module (52) is used to compare the expected value (L) with the component (52). E I E M E ) and the actual values ​​of physical parameters that occur during the welding process using welding tool (21) (L ACT In_ ACT Mn_ ACT (S2) to compare the force (F) detected during the welding process using the welding tool (21). S (t), F S_ACT The reliability of the actual value is verified, wherein the measurement module (51) uses the model (511) of the welding tool (21) to measure the expected value (L). E I E M E The physical parameter is the position of at least one electrode (22, 23) of the welding tool (21), and the model (511) includes the modeled arm bending (A) of the welding tool (21). B ), or wherein the physical parameter is the driving current (In) of the driving mechanism (26) for driving at least one electrode (22, 23) of the welding tool (21), or wherein the physical parameter is the torque (M) of the driving mechanism (26) for driving at least one electrode (22, 23) of the welding tool (21).

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