Method and application system for applying viscous material to workpieces

Abstract

A method for applying viscous material (12) to workpieces (14), in particular to fully or partially assembled vehicle bodies (78) or parts (80, 82, 84, 92) of vehicle bodies (78), comprises the following steps: a) applying viscous material (12) with an application device (16); b) movably guiding the application device (16) with a movement device (18); c) defining target application positions which specify position criteria with reference to reference structures (46) of the workpiece (14); d) controlling the movement device (18) by means of a control device (40) on the basis of the target application positions, such that the application device (16) is guided to application positions (42) in order to apply viscous material (12) to an application point (44) on the workpiece (14) there.According to the invention, e) an application position (42) of the application device reached on the basis of a target application position defines an actual application position; f) deviations of an actual application position (42) from the position criteria of the associated target application position are detected by means of a monitoring device (52); fb) in the event of a deviation exceeding a predetermined threshold value, a corrected actual application position is calculated which fulfills the position criteria at least better than the actual application position (42); fc) the movement device (18) and the application device (16) are controlled such that the application device (16) is moved into the corrected actual application position and there applies viscous material (12) to a resulting application point (44). Furthermore, an application system (10) is specified with which this method can be carried out.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The invention relates to a method for applying viscous material to workpieces, in particular to fully or partially assembled vehicle bodies or parts of vehicle bodies, comprising the following steps: a) applying viscous material using an application device; b) Movable guidance of the application device with a movement device; c) Defining target application positions which specify positioning criteria related to reference structures of the workpiece; d) Controlling the movement device by means of a control device on the basis of the desired application positions, such that the application device is guided to application positions in order to apply viscous material to an application point on the workpiece.

[0002] Furthermore, the invention relates to an application system for applying viscous material to workpieces, in particular to fully or partially assembled vehicle bodies or parts of vehicle bodies, with a) an application device by means of which the material can be applied; b) a movement device by means of which the application device is movably guided; c) a control device in which defined target application positions are stored, which specify position criteria related to reference structures of the workpiece;wherein d) the movement device can be controlled by means of the control device on the basis of the target application positions in such a way that the application device is guided to application positions in order to apply material to an application point on the workpiece.

[0003] Furthermore, the invention relates to an application system for applying viscous material to workpieces, in particular to fully or partially assembled vehicle bodies or parts of vehicle bodies, with a) an application device by means of which the viscous material can be applied; b) a movement device by means of which the application device is movably guided; c) a control device in which defined target application positions are stored, which specify position criteria related to reference structures of the workpiece;wherein d) the movement device can be controlled by means of the control device on the basis of the desired application positions in such a way that the application device is guided to application positions in order to apply viscous material to an application point on the workpiece.

[0004] An application position of the application device includes its location, alignment and orientation in space.

[0005] The invention is described below by way of example in connection with the manufacture of vehicles and the application of viscous material to partially or fully assembled vehicle bodies or parts of vehicle bodies. However, the described concepts can also be implemented and applied to other workpieces for the manufacture of objects. 2. Description of the state of the art

[0006] During the manufacturing of objects, and specifically of vehicles, there are various phases in which viscous materials, commonly referred to as thick materials, are applied. Typically, such viscous materials have a viscosity η of greater than 300 mPas or 0.3 kg m -1 s -1 , usually greater than 500 mPas or 0.5 kg m -1 s -1 .

[0007] These include, for example, viscous adhesives, viscous sealing materials, and viscous corrosion protection materials. In vehicle body construction, individual sheets of metal are bonded together using viscous adhesives, at least in addition to other joining techniques such as welding. Viscous sealing materials are also applied to the corresponding joints of individual components as part of the seam sealing process before the vehicle body is painted. Viscous corrosion protection materials may also be applied after the vehicle body has been painted. Since the corrosion protection materials remain visible in this case, this is particularly common in commercial vehicles.

[0008] The target application positions together result in a target application pattern that covers the target application points on the workpiece. In particular, the viscous materials are applied as a continuous material bead, i.e. as a continuous material strand, over at least a section of the workpiece. For this purpose, the application positions are defined in such a sequential manner that a continuous movement of the application device results and the viscous material is applied as a continuous material bead. The viscous material can also be applied as material points, i.e. as point-shaped material volumes, or as a row of such material points spaced apart from one another. In addition, the viscous material can also be applied over a large area as a type of material carpet. Corresponding target application positions are also specified for such point-shaped or surface-wide applications.

[0009] Depending on the application position of the application device relative to the workpiece, the application point on the workpiece to which the viscous material is applied is determined. The target application positions for the application device are defined accordingly so that – taking into account the dispensed quantity per unit time – the desired application points are coated, allowing the respective viscous material to fulfill its function at the correct location on the workpiece.

[0010] It is common practice in the market to determine the target application positions prior to the application process through simulation on a digital model, usually a CAD model, of the workpiece to be coated. Such a digital model provides workpiece reference structures, which in turn form the basis for the related positioning criteria for the target application positions. Such workpiece reference structures are structures that are inherent in the workpiece itself and are not specifically attached to the workpiece.

[0011] For a material bead to be applied along the outer edge of a vehicle door, for example, the surrounding outer edge of the vehicle door can provide such a workpiece reference structure. If application is required in areas further inward from the outer edge, structures closer to the intended application location, such as beads, troughs, struts, elevations, or the like, can serve as suitable workpiece reference structures.

[0012] However, a digital model reflects an ideal state of a workpiece, which is rarely encountered in reality, as tolerances occur during workpiece manufacturing and the final workpiece geometry deviates from this ideal. Particularly when a workpiece is manufactured by joining and connecting two or more components, as is the case with vehicle body parts and vehicle bodies themselves, deviations from the ideal position of the components relative to each other, as specified by the digital model, occur.

[0013] However, if the target application position is not in the correct relationship to the actual workpiece geometry, this application position will result in an incorrect application point and, as a result, a material bead that does not cover all the necessary parts of the workpiece.

[0014] Therefore, in the production facility, correction values ​​for position tolerances are determined and taken into account by completely measuring the workpiece to be applied, possibly including a vehicle body. A vehicle body, for example, can be completely measured by determining the positions of specified reference points on the vehicle body. Deviations between the CAD model and the actual workpiece are compensated for by manually correcting the target application positions.

[0015] However, if the accuracy requirements of the application are higher and individual shape deviations of the workpiece must be taken into account, the motion device, usually a multi-axis application robot, usually performs a preliminary measurement run without application to determine the required correction values ​​for the path guidance. For this purpose, the motion device is equipped with a scanning device that can detect deviations from the digital model.

[0016] However, these manual adjustments and the measuring runs, which may have to be carried out individually for each workpiece, significantly increase the treatment time and thus reduce the process throughput. SUMMARY OF THE INVENTION

[0017] It is therefore an object of the invention to provide a method and a device of the type mentioned at the outset which take these ideas into account.

[0018] This task is solved in the method of the type mentioned above by e) an application position of the application device achieved on the basis of a target application position defines an actual application position; f) by means of a monitoring device fa) Deviations of an actual application position from the position criteria of the corresponding target application position are recorded; fb) in the case of a deviation which lies within a predetermined threshold range which is defined at least by a lower threshold limit value, a corrected actual application position is calculated which fulfils the position criteria at least better than the actual application position; fc) the movement device and the application device are controlled in such a way that the application device is moved into the corrected actual application position and there applies viscous material to a resulting application point.

[0019] The invention is based on the finding that, in contrast to previous concepts, it is possible to check during the ongoing application process whether an actual application position sufficiently meets the position criteria for the real workpiece so that the viscous material can be applied with the required accuracy and quality, and if necessary to correct the application process with regard to the application position of the application device.

[0020] The digital model of the workpiece represents a kind of initial map of the target application pattern and the target application positions required for this, against which the actual application positions of the application device can be compared.

[0021] This reduces the effort required for programming and commissioning an application device, especially for the aforementioned thick material and hole sealing applications, and improves the precision of the application. Time-consuming preliminary measurements and test runs are no longer necessary.

[0022] It was discovered that reference structures with a thickness of down to 0.88 mm, typical for car body construction, can be detected and taken into account. By comparing the actual application positions, it is possible to achieve the application of the viscous material along the target path related to the reference structures with high accuracy. Depending on the type and objective of the application, material beads are usually applied at speeds of 250 mm s. -1 with visible remaining material strands and 400 mm s -1 applied to so-called coarse seams in areas that remain invisible.

[0023] The method according to the invention can be implemented particularly during a movement of the workpiece. The workpiece can be moved in continuous systems or booths at speeds of up to 2 ms -1 be promoted.

[0024] The threshold range can be defined only by the lower threshold limit value and thus as an upwardly open threshold range, so that the corrected actual application position is generally calculated according to step fb) above if the actual application position deviates from the position criteria of the associated target application position beyond the lower threshold limit value.

[0025] However, it is advantageous if the threshold range is defined by the lower threshold limit value and also by an upper threshold limit value, wherein a separate process measure is initiated by means of the monitoring device in the event of a deviation of the actual application position from the position criteria of the associated target application position beyond the upper threshold limit value.

[0026] As a separate process measure, for example, an error message can be generated and stored in a type of log so that the application can be specifically checked for its quality in a downstream audit process at the application point(s) in question.

[0027] In extreme cases, however, the separate process measure may also mean that the application is aborted if, for example, the upper threshold limit value as a test parameter indicates that the workpiece must be classified as structurally defective. In this case, it may be advisable to remove the workpiece from the production process.

[0028] The process is particularly effective when target application positions are specified in such a way that one or more beads of viscous material are applied to the workpiece.

[0029] It is advantageous if established modeling techniques are implemented and the target application positions and their positioning criteria are created using a digital model of the workpiece.

[0030] Effective data processing can be achieved if the target application positions are stored in the control device with an application data record.

[0031] For the application process, it is advantageous if the application data set provides additional application parameters for each target application position, in particular the type of viscous material to be applied, the type of application head to be used or the volume flow with which the viscous material is to be applied.

[0032] With regard to technical implementation, it is advantageous if a) reference structures of the workpiece are detected by means of a sensor system which outputs sensor signals representing the reference structures; b) the relative position of the application device in its actual application position is determined in the form of actual position data based on the sensor signals of the sensor system; c) the actual position data are compared with the position criteria of the target application positions.

[0033] For this purpose, an optical sensor system is advantageously used, which provides a sensor field with or in which the workpiece is optically scanned and scanned.

[0034] Preferably, the sensor field is covered by one or more sensor units, each of which optically detects and scans a scanning area in the vicinity of a respective application point.

[0035] A laser scanner or an imaging camera is preferably used as a sensor unit.

[0036] It is advantageous if at least one sensor unit is carried by the movement device in such a way that it follows the movement of the application device.

[0037] Alternatively or additionally, one or more sensor units can be distributed in the room independently of the movement device.

[0038] It is advantageous if the optical sensor system is also used to check the quality of the application carried out, in particular based on the width, thickness and structure of the applied viscous material.

[0039] The preferred movement device is a multi-axis application robot with a handpiece that carries the application device.

[0040] The above-mentioned task is solved in an application system of the type mentioned above by e) an application position of the application device achieved on the basis of a target application position defines an actual application position f) a monitoring device is provided and arranged in such a way that it fa) a deviation of an actual application position from the position criteria of the corresponding target application position is recorded; fb) in the case of a deviation which lies within a predetermined threshold range which is defined at least by a lower threshold limit value, calculates a corrected actual application position which fulfils the position criteria at least better than the actual application position; fc) ensures that the movement device and the application device are controlled in such a way that the application device is moved into the corrected actual application position and there applies viscous material to a resulting application point.

[0041] In this regard and in relation to subsequent developments, what has been said about the corresponding procedural features above applies accordingly.

[0042] Preferably, therefore, the threshold range is defined by the lower threshold limit value and also by an upper threshold limit value, wherein the monitoring device is arranged in such a way that, in the event of a deviation of the actual application position from the position criteria of the associated target application position beyond the upper threshold limit value, it initiates a separate process measure, in particular an error message or a termination of the application.

[0043] It is advantageous if target application positions are specified in such a way that one or more beads of viscous material are applied to the workpiece.

[0044] Preferably, the target application positions and their positioning criteria are created using a digital model of the workpiece.

[0045] Further preferably, the target application positions are stored in the control device with an application data record.

[0046] It is advantageous if the application data set provides further application parameters for each target application position, in particular the type of viscous material to be applied, the type of application head to be used or the volume flow with which the viscous material is to be applied.

[0047] It is particularly advantageous if a) a sensor system is present which detects reference structures of the workpiece and which outputs sensor signals representing the reference structures; b) the monitoring device is configured in such a way that the relative position of the application device in its actual application position is determined in the form of actual position data on the basis of the sensor signals of the sensor system; c) the monitoring device is set up in such a way that the actual position data are compared with the position criteria of the target application positions.

[0048] A technically good solution is that the sensor system is an optical sensor system, which provides a sensor field with or in which the workpiece is optically scanned and scanned.

[0049] The sensor field is advantageously covered by one or more sensor units, each of which optically records and scans a scanning area in the vicinity of a respective application point.

[0050] Preferably, a sensor unit is a laser scanner or an imaging camera.

[0051] It is advantageous if at least one sensor unit is carried along by the movement device in such a way that it follows the movement of the application device.

[0052] Advantageously, a protection system is provided with which the sensor unit can be protected at least temporarily from external influences on the application device.

[0053] The protection system is preferably formed in that the sensor unit is movably supported on the movement device by means of a holder and is movable between a scanning position and a rest position, in which it is further away from the application device than in the scanning position. In this way, the sensor unit can be removed from the application device in narrower or inaccessible application areas. Alternatively or additionally, the protection system can comprise a covering device with which the sensor unit can be temporarily covered, a sealing air device with which the sensor unit can be at least partially or completely flooded with a sealing air curtain, or a wiping device with which the sensor unit can be freed of harmful contaminants by wiping it off.

[0054] Alternatively or additionally, one or more sensor units can be distributed in the room independently of the movement device.

[0055] Preferably, the movement device is a multi-axis application robot with a handpiece that carries the application device. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings, in which: Fig. 1 an application system for applying viscous material to workpieces; Fig. 2A and Fig. 2B shows an external plan view of a side and the roof of a commercial vehicle; Fig. 3 a plan view of the inside of the floor panel of the commercial vehicle; Fig. 4A, Fig. 4B and Fig. 4C shows a plan view of the inside of a passenger door, a side sliding door and a rear door of the commercial vehicle; Fig. 5 schematically shows the application of viscous material to the inside of the floor panel of Fig. 3; Fig. 6 schematically shows the application of viscous material to the inside of the doors of Fig. 4. DESCRIPTION OF PREFERRED EMBODIMENTS 1. Application system and method

[0057] Fig. 1 shows an application system 10 for applying viscous material 12 to workpieces 14. As mentioned above, a viscous material 12 has a viscosity of greater than 300 mPas and usually greater than 500 mPas.

[0058] The application system 10 comprises an application device 16, which is movably guided by means of a movement device 18.

[0059] The application device 16 comprises an application head 20 with an application nozzle 22 from which the viscous material 12 is dispensed. In the present embodiment, the application head 20 is designed as an interchangeable adapter or interchangeable head, so that it can be exchanged in the movement device 18 for application heads 20 with different functionality. Fig. Figure 1 illustrates this using the example of two application heads 20a, 20b, each with a differently designed application nozzle 22a, 22b. Different functionalities can be demonstrated, for example, by different diameters of the application nozzle's discharge opening and / or different nozzle geometries, which can be adapted to the locations to be reached on different workpieces.

[0060] In the present embodiment, the movement device 18 is capable of positioning and aligning the application device 16 in all six degrees of freedom within the working range accessible by the movement device 18.

[0061] For this purpose, the movement device 18 used is in particular a Fig. 1, a multi-axis application robot 24 is considered, as is known per se and is shown here with four axes of motion A1, A2, A3, and A4. The application robot 24 defines a base part 26, a drive part 28, an articulated arm 30 with a proximal and a distal arm part 30a and 30b, respectively, and a handpiece 32. Here, the handpiece 32 carries the application device 16.

[0062] In modifications not specifically shown, the movement device 18 can also be designed differently, for example as a side machine or the like, and can provide more or fewer than the four movement axes shown and possibly fewer than six degrees of freedom of movement for the application device 16.

[0063] The application system 10 comprises a supply device 34, with which the application device 16 can be supplied with viscous material 12. The viscous material 12 to be applied is conveyed from a material reservoir 36 to the application device 16 using established dosing technology via a line system 38 indicated by dashed lines. In the present embodiment, three material reservoirs 36 in the form of storage containers are carried by the application robot 24, in which various viscous materials 12.1, 12.2, and 12.3 can be stored. However, a material reservoir 36 can also be arranged centrally and separately from the movement device 18, for example, and optionally also be provided by a ring line.

[0064] The application system 10 also comprises a control device 40, by means of which the movement device 18 and the application device 16 as well as the supply device 34 are controlled, which is illustrated by dash-dotted control lines B1, B2, B3.

[0065] With the aid of the control device 40, the movement device 18 and the application device 16 can be controlled in such a way that the application device 16 is guided to application positions and, in a respective application position, applies the viscous material 12 to the application point on the workpiece. Fig. 1 shows, as a snapshot, the application device 16 in an application position 42, from which the viscous material 12 is to be or will be applied to an associated application site 44.

[0066] The control of the application device 16 naturally also includes the control of the supply device 34 to supply the application device 16 with viscous material 12. If several viscous materials 12 are available, such as the viscous materials 12.1, 12.2, and 12.3 here, it is also controlled which of these materials 12 is applied. Any necessary replacement with installation of an application head 20 can also be carried out by the control device, i.e., automatically, or manually by a worker.

[0067] As explained above, target application positions are defined, which specify positioning criteria relative to reference structures 46 of the workpiece 14. The target application positions and their positioning criteria are created using a digital model of the workpiece 14, as explained above.

[0068] In Fig. 1, the position criteria refer to an outer edge 48 of the workpiece 14, along which the viscous material 12 is to be applied. The target application positions required for a specific application process on a specific workpiece 14 for applying the workpiece 14 or a specific part of the workpiece 14 are stored in the control device 40 with an application data record 50, which is illustrated schematically here.

[0069] An application data set 50 can provide additional application parameters to the control device 40 for each target application position included, for example, which viscous material 12 should be applied at the target application position, which application head 20 should be used, or the volume flow rate with which the viscous material 12 should be applied. The control device 40 controls the required system components according to these specifications.

[0070] In any case, the movement device 18 is controlled on the basis of the stored target application position, whereby the application device 16 is moved into an application position 42, which now defines an actual application position relative to the real workpiece 14 to be applied.

[0071] The application system 10 also comprises a monitoring device 52, with the aid of which it can be detected whether this actual application position deviates from the position criteria of the associated target application position.

[0072] For this purpose, the monitoring device 52 comprises a sensor system 54 by means of which reference structures can be detected and which outputs sensor signals that represent and reflect the reference structures.

[0073] The sensor system 54 is preferably an optical sensor system, but can also be a mechanical / haptic sensor system that physically scans the surface of the workpiece 14 with a measuring probe.

[0074] Based on the sensor signals transmitted by the sensor system 54, the monitoring device 52 determines the relative position of the application device 16 in its actual application position in the form of actual position data, which can be compared with the position criteria of the target application position. For this purpose, the actual position data corresponds to the data structure of the position criteria in terms of the structure and information content of the associated data.

[0075] Using the example of Fig. 1 as a reference structure 46, it can be determined, for example, that the actual application position is offset too far inwards from the outer edge 48, so that the viscous material 12 would be applied correspondingly too far away from the outer edge 48.

[0076] If the comparison reveals that the actual application position deviates from the positioning criteria within a predefined threshold range defined at least by a lower threshold limit, the monitoring device 52 calculates a corrected actual application position that fulfills the positioning criteria at least better than the actual application position. The lower threshold limit takes into account that small deviations can or must be accepted without resulting in quality losses during the application. Such lower threshold limit values ​​are defined prior to the application.

[0077] The monitoring device 52 then ensures in a further step that the movement device 18 and the application device 16 are controlled in such a way that the application device 16 is moved into the corrected actual application position and is applied there to a resulting application site.

[0078] As explained above, the threshold range can be open-ended if only the lower threshold limit is specified. If the threshold range is also defined by an upper threshold limit, this upper threshold limit can specify a maximum deviation that can or should still be tolerated or compensated for by calculating a corrected actual application position.

[0079] If the actual application position deviates from the positioning criteria of the corresponding target application position beyond this upper threshold, this indicates that the differences between the workpiece 14 and the underlying digital model can no longer be easily tolerated. For quality reasons, it is then advisable to at least review the application more thoroughly. One or more error messages can be stored in a type of error log so that the application can be specifically reviewed for quality in the area in question and at the application point(s) in question, for example, in a downstream audit process.

[0080] If necessary, the application can also be aborted if, for example, the workpiece 14 is classified as structurally defective and must be removed from the production process.

[0081] The monitoring device 52 preferably comprises and uses the control device 40 and uses its computing capacity, for which purpose the sensor data of the sensor system 54 are sent to the control device 40 via signal lines. Signal lines are in Fig. 1 illustrated by dashed-colon lines.

[0082] In the case of an optical sensor system 54, this provides a sensor field 56 with or in which the workpiece 14 can be optically sensed and scanned. For this purpose, the sensor system 54 comprises one or more sensor units 58, each of which can optically detect and scan a scanning area 60 in the vicinity of a respective application point 44. In the case of multiple sensor units 58, their multiple scanning areas 60 cover the sensor field 56 of the sensor system 54. If the sensor system 54 comprises only a single sensor unit 58, its scanning area 60 simultaneously defines the sensor field 56.

[0083] Imaging cameras, laser scanners or imaging laser scanners are particularly suitable as sensor units 58.

[0084] In a first embodiment, a sensor unit 58 of the sensor system 54 is carried by the movement device 18 such that it follows the movement of the application device 16 and can optically detect and scan a scanning area 60 in the vicinity of the application site 44. In this case, the sensor unit 58 is in particular a laser scanner 62, but an imaging camera 64 is also suitable as the sensor unit 58.

[0085] Typically, the sensor unit 58 is arranged close to the application head 20 on the movement device 18. In an application robot 24, the sensor unit 58 is attached, for example, to the handpiece 32. During application, situations may arise in which the sensor unit 58 must be protected from external influences.

[0086] Since a sensor unit 58 can be structurally relatively large, it can reduce the working range of the movement device 18. For example, the sensor unit 58 can block movement of the application robot 24, particularly when narrow areas in the interior of a vehicle body must be provided with a viscous material 12. Then, there is a risk that the sensor unit 58 will collide with surrounding components and become damaged. In another aspect, the sensor unit 58 can be exposed to an ambient atmosphere in which it can be damaged. In general, therefore, external influences can occur from which the sensor unit 58 must be protected.

[0087] Therefore, a protection system 65 can be provided by which the sensor unit 58 can be protected at least temporarily from external influences from the application device 16.

[0088] In one embodiment shown here, the protection system 65 can be formed by the sensor unit 58 being movably supported by a holder 66 and being movable between a scanning position and a rest position. In the rest position, the application device 16 is further away from the application device 16 than in the scanning position and is arranged at the greatest possible distance from the application head 20. The movement can be achieved, for example, by folding, pivoting, or shifting.

[0089] In Fig. 1, this is schematically illustrated by a support rail 68, on which the sensor unit 58 is slidably mounted and can be moved between the scanning position and the rest position and thus removed from the application head 20. In the rest position, the sensor unit 58 is in Fig. 1 with dashed lines. In a modification, the holder 66 can also be designed such that the sensor unit 56 can be moved away from the movement device 18 as such. For this purpose, the holder can be designed, for example, as a pivoting or articulated arm or the like.

[0090] In addition to the shock protection, the sensor unit 58 is also protected from the influence of an ambient atmosphere at the application head 20, since it is moved away from there.

[0091] The protection system 65 can also be configured such that the sensor unit 58 is protected from the influences of the ambient atmosphere at the application head 20 even without movement away from the application head 20. For this purpose, the protection system 65 can comprise, for example, a covering device, a sealing air device, or a wiping device, which are not specifically shown here. The sensor unit 58 can be temporarily covered with a covering device. With the aid of a sealing air device, the sensor unit 58 can be at least partially or completely flooded with a sealing air curtain. A wiping device can be used to periodically wipe off any impurities that may be harmful to its function.

[0092] In a second embodiment, the sensor system 54 comprises a plurality of sensor units 58, which are arranged spatially distributed independently of the movement device 18. In this case, imaging cameras 68 are used in particular. Using known image analysis algorithms, the actual application position can be detected in relation to the workpiece 14 and / or its reference structures 46.

[0093] Fig. 1 illustrates this alternative using three cameras 64, each with a scanning area 60, which together cover the sensor field 56.

[0094] The sensor system 54 can also operate with one or more sensor units 58 on the movement device 18 as well as with one or more sensor units 58 in the room. For example, a laser scanner 62 on the movement device 18, in particular on an application robot 24, and one or more imaging cameras 64 in the room can work together to establish and scan the sensor field 56 of the sensor system 54.

[0095] In principle, image evaluation algorithms known from so-called pick-and-place applications can be used to evaluate the sensor signals from imaging cameras 64, ie their camera images. 2. Application to a vehicle body

[0096] The Fig. 2 to 6 illustrate the application of the described concept and method as well as the described application system using the example of the application of viscous material for corrosion protection and seam sealing in a commercial vehicle 70 with material strands 72.

[0097] Fig. 2 shows plan views of sections of a right side wall 74 and the roof 76 of a vehicle body 78 of a commercial vehicle 70 in the form of a so-called van.

[0098] Its passenger doors 80 and rear doors 82 as well as a side sliding door 84 are in Fig. 4 and in Fig. 2 only indicated by dashed lines.

[0099] On the outside of the Fig. 2A and the right side wall 74 shown in Fig. 2B, material strands 72 of viscous material 12 are applied as material beads 86, which are not always provided with a reference symbol, as is also Fig. 1. For this purpose, the target application positions are specified such that one or more material beads 86 made of viscous material 12 are applied to the workpiece 14.

[0100] The viscous material 12 here provides a corrosion protection material 88. A viscous material 12 used as a corrosion protection material 88 is applied in practice to the painted vehicle body 78, so that the corrosion protection material 88 remains visible after it has dried / cured, even during use of the commercial vehicle 70.

[0101] The Fig. 3 and Fig. 4 illustrate the application of viscous material 12, which provides a material 90 for seam sealing and is applied to the corresponding components in the interior areas of the vehicle body 78 during vehicle manufacture before the painting of the vehicle body. Fig. 3 shows a section of a floor panel 92. The application for the doors 80, 82, and 84 can also be performed on the workpieces 14 before they are integrated into the vehicle body 78. After the drying / curing of the material 90 for seam sealing, the material strands 72 are also coated with the paint and overpainted accordingly during the painting of the vehicle body 78 or its components. Alternatively, the material strands 72 can also be overpainted without prior drying or curing and then dried together with the paint layer.

[0102] However, all components to be applied provide the reference structures 46 mentioned above.

[0103] In the case of applications on large-area components such as the side wall 74, the roof 76 or the floor panel 92, the application points 44 are usually removed from an adjacent outer edge or a neighboring outer edge, so that this or these cannot be considered as a reference structure 46.

[0104] Therefore, as mentioned at the beginning, structures such as beads, troughs, struts, elevations or the like that are closer to the intended application point are used.

[0105] For the side wall 74, this can be, for example, the edge of the sheet metal recess 94 for a section of the material bead designated separately by 86a. For the roof 76, the reinforcement folds 96 or the beads there can be used as reference structures 46. For the floor panel 92, there are several workpiece structures that can serve as reference structures 46. In particular, for floor panels of vehicle bodies, there are suitable reinforcement structures 98 or passages 100 for this purpose.

[0106] Frequently, especially in the application of corrosion protection materials 88, the material bead 86 is applied along a gap 102 between two components 104, 106 of the workpiece 14. This illustrates again Fig. 5, in which these two components 104, 106 are attached to a third component 108. In these cases, the respective outer edges 110 and 112 of these components 104, 106, which form the lateral boundaries of the gap 102, can be used as the reference structure 46.

[0107] The gap 102 is generally intended to represent areas of workpieces 14 in which sheets are attached to one another in an overlapping manner.

[0108] In general, the sensor system can detect 54 reference structures, and in particular sheet metal overlaps, with a thickness of 0.88 mm. By comparing the actual application positions, it is possible to achieve the application of the viscous material 12 along the target path related to the reference structures with an accuracy of + / - 1.0 mm at application speeds of up to 600 mm s. -1 can be done.

[0109] If, during the application process, monitoring device 52 determines that an actual application position does not meet the positioning criteria specified by the digital model with respect to one or both outer edges 110, 112, the correction algorithm described above is applied. The example of gap 102 also shows that it may be impossible to meet the specified positioning criteria: For example, if component 106 is positioned incorrectly at a slight angle when joining components 104, 106, and 108, gap 102 may diverge in one direction. However, if both the distances to both outer edges 110, 112 constitute the positioning criteria, these can never be met, since the distance between the outer edges 110, 112 no longer matches the specifications.

[0110] In this case, a corrected actual application position is calculated and approached that fulfills the positioning criteria as well as possible, for example, by achieving an equal distance to both outer edges 110, 112 so that the material bead 86 is applied centrally in the gap 102. This reflects a corrected actual application position that fulfills the positioning criteria at least better than the actual application position.

[0111] If components 104, 106, 108 are incorrectly connected to one another to such an extent that a correspondingly specified threshold range with a lower threshold limit and an upper threshold limit cannot be met, a corresponding error message can be generated - as explained above - and stored in a type of log so that the application, in this case the seam seal, can be specifically checked for quality in the area in question and at the application point(s) in question, for example, in a downstream audit process. Here, too, exceeding the upper threshold limit can lead to the separate process measure of aborting the application.

[0112] Fig. For the sake of completeness, Figure 5 additionally illustrates other reference structures 46 which can be used for the method in a corresponding manner.

[0113] For vehicle doors, such as doors 80, 82, and 84, a respective outer edge of the workpiece 14, which is again designated 48, is generally a reliable reference structure. However, structures in the radially inner region of the components that are remote from the respective outer edge 48 can also be used for this purpose. These can be, for example, the outer edges of window cutouts 114, if present, as is the case with the passenger door 80. In the case of closed doors without windows, corresponding depressions 116 can be present relative to the inside where windows are usually found, as is the case with the rear doors 82 and the sliding door 84. The boundaries of such depressions 116 are again suitable, for example, as a reference structure 46.

[0114] Fig. 6 illustrates again in a larger view the method principle using a section of the vehicle door 80 at its outer edge 48, wherein again spaced-apart inner reference structures 46 are illustrated graphically.

[0115] The reference structures 46 described here are, as mentioned above, workpiece reference structures which are present due to the design of the workpiece 14 as such and are not specifically attached to the workpiece.

[0116] In a modification, however, one or more separate marker reference structures can also be attached to the workpiece 14 before the application process, the positions and configurations of which are stored accordingly in the predetermined application data set 50.

[0117] As explained above, an application data record 50 can provide additional information about the type of viscous material 12, the application head 20 or the volume flow of the viscous material 12 to the control device 40 for each included target application position.

[0118] As the Fig. 2, Fig. 3 and Fig. 4, there are sections 118 between two adjacent material strands 72 of material beads 86 in the workpieces 14, in which no viscous material 12 is applied, and sections 120, in which a different viscous material 12 than the viscous material 12 applied up to that point is applied. Only by way of example are sections 118 in the floor plate 92 in Fig. 3 and the passenger door 80 in Fig. 4A and sections 120 at the passenger door 80 and the rear door 82 in the Fig. 4A and Fig.4B, without necessarily corresponding to such areas in reality. A material change during the application process can also coincide with a change of the application head 20.

[0119] An optical sensor system 54 can additionally be used to check the quality of the application carried out largely immediately after application.

[0120] With the help of the optical sensor system 54, for example, the width, thickness and structure of the applied viscous material 12 can be checked.

Claims

[1] Method for applying viscous material (12) to workpieces (14), in particular to fully or partially assembled vehicle bodies (78) or parts (80, 82, 84, 92) of vehicle bodies (78), comprising the following steps: a) applying viscous material (12) with an application device (16); b) Movable guidance of the application device (16) with a movement device (18); c) defining target application positions which specify position criteria with respect to reference structures (46) of the workpiece (14); d) controlling the movement device (18) by means of a control device (40) on the basis of the desired application positions, such that the application device (16) is guided to application positions (42) in order to apply viscous material (12) to an application point (44) on the workpiece (14) there; characterized in that e) an application position (42) of the application device reached on the basis of a target application position defines an actual application position; f) by means of a monitoring device (52) fa) deviations of an actual application position (42) from the position criteria of the associated target application position are recorded; fb) in the case of a deviation which lies within a predetermined threshold value range which is defined at least by a lower threshold limit value, a corrected actual application position is calculated which fulfils the position criteria at least better than the actual application position (42); fc) the movement device (18) and the application device (16) are controlled in such a way that the application device (16) is moved into the corrected actual application position and there applies viscous material (12) to a resulting application point (44). [2] Method according to claim 1, characterized by that the threshold value range is defined by the lower threshold limit value and also by an upper threshold limit value, wherein by means of the monitoring device (52) a separate process measure, in particular an error message or a termination of the application, is initiated in the event of a deviation of the actual application position from the position criteria of the associated target application position beyond the upper threshold limit value. [3] Method according to claim 1 or 2, characterized by that target application positions are specified such that one or more material beads (86) made of viscous material (12) are applied to the workpiece (14). [4] Method according to one of claims 1 to 3, characterized by that the target application positions and their position criteria are created using a digital model of the workpiece (14). [5] Method according to one of claims 1 to 4, characterized by that the target application positions are stored with an application data record (50) in the control device (40). [6] Method according to claim 5, characterized by that the application data record (50) provides further application parameters for each target application position, in particular the type of viscous material (12) to be applied, the type of application head (20) to be used or the volume flow with which the viscous material (12) is to be applied. [7] Method according to one of claims 1 to 6, characterized by , that a) reference structures (46) of the workpiece (14) are detected by means of a sensor system (54) which outputs sensor signals representing the reference structures; b) the relative position of the application device (16) in its actual application position is determined in the form of actual position data on the basis of the sensor signals of the sensor system (54); c) the actual position data are compared with the position criteria of the target application positions. [8] Method according to claim 7, characterized by that an optical sensor system (54) is used which provides a sensor field (56) with or in which the workpiece (14) is optically scanned and scanned. [9] Method according to claim 8, characterized by that the sensor field (56) is covered by one or more sensor units (58), with each of which a scanning area (60) in the vicinity of a respective application point (44) is optically detected and scanned. [10] Method according to claim 9, characterized by that a laser scanner (62) or an imaging camera (64) is used as a sensor unit (58). [11] Method according to claim 9 or 10, characterized by that at least one sensor unit (58) is carried along by the movement device (18) in such a way that it follows the movement of the application device (16). [12] Method according to one of claims 9 to 11, characterized by that one or more sensor units (58) are distributed in the room independently of the movement device (18). [13] Method according to one of claims 8 to 12, characterized by that the optical sensor system (54) is also used to check the quality of the application carried out, in particular based on the width, thickness and structure of the applied viscous material (12). [14] Method according to one of claims 1 to 13, characterized by that a multi-axis application robot (24) with a hand part (32) which carries the application device (16) is used as the movement device (18). [15] Application system for applying viscous material (12) to workpieces (14), in particular to fully or partially assembled vehicle bodies (78) or parts (80, 82, 84, 92) of vehicle bodies, with a) an application device (16) by means of which the viscous material (12) can be applied; b) a movement device (18) by means of which the application device (16) is movably guided; c) a control device (40) in which defined target application positions are stored, which specify position criteria with respect to reference structures (46) of the workpiece; wherein d) the movement device (18) can be controlled by means of the control device (40) on the basis of the desired application positions in such a way that the application device (16) is guided to application positions (42) in order to apply viscous material (12) to an application point (44) on the workpiece (14) there; characterized in that e) an application position of the application device (16) achieved on the basis of a target application position defines an actual application position f) a monitoring device (52) is provided and arranged in such a way that it fa) a deviation of an actual application position from the position criteria of the corresponding target application position is recorded; fb) in the case of a deviation which lies within a predetermined threshold range which is defined at least by a lower threshold limit value, calculates a corrected actual application position which fulfils the position criteria at least better than the actual application position; fc) ensures that the movement device (18) and the application device (16) are controlled in such a way that the application device (16) is moved into the corrected actual application position and there applies viscous material (12) to a resulting application point (44). [16] Application system according to claim 15, characterized bythat the threshold value range is defined by the lower threshold limit value and also by an upper threshold limit value, wherein the monitoring device (52) is arranged in such a way that, in the event of a deviation of the actual application position from the position criteria of the associated target application position beyond the upper threshold limit value, it initiates a separate process measure, in particular an error message or an abort of the application. [17] Application system according to claim 15 or 16, characterized by that target application positions are predetermined such that one or more material beads (86) made of viscous material (12) are applied to the workpiece (14). [18] Application system according to one of claims 15 to 17, characterized by that the target application positions and their position criteria are created based on a digital model of the workpiece (14). [19] Application system according to one of claims 15 to 18, characterized by that the target application positions are stored with an application data record (50) in the control device (40). [20] Application system according to claim 19, characterized by that the application data record (50) provides further application parameters for each target application position, in particular the type of viscous material (12) to be applied, the type of application head (20) to be used or the volume flow with which the viscous material (12) is to be applied. [21] Application system according to one of claims 15 to 20, characterized by , that a) a sensor system (54) is provided, with the aid of which reference structures (46) of the workpiece (14) are detected and which outputs sensor signals which represent the reference structures; b) the monitoring device (52) is configured such that the relative position of the application device (16) in its actual application position is determined in the form of actual position data on the basis of the sensor signals of the sensor system (54); c) the monitoring device (52) is arranged such that the actual position data are compared with the position criteria of the target application positions. [22] Application system according to claim 21, characterized by that the sensor system (54) is an optical sensor system which provides a sensor field (56) with or in which the workpiece (14) is optically scanned and scanned. [23] Application system according to claim 22, characterized by that the sensor field (56) is covered by one or more sensor units (58), with each of which a scanning area (60) in the vicinity of a respective application point (44) is optically detected and scanned. [24] Application system according to claim 23, characterized by that a sensor unit (58) is a laser scanner (62) or an imaging camera (64). [25] Application system according to claim 23 or 24, characterized by that at least one sensor unit (58) is carried along by the movement device (18) in such a way that it follows the movement of the application device (16). [26] Application system according to claim 25, characterized by that a protection system (65) is provided with which the sensor unit (58) can be protected at least temporarily from external influences on the application device (16). [27] Application system according to claim 26, characterized byin that the protective system (65) is formed in that the sensor unit (58) is movably supported on the movement device (18) by means of a holder (66) and is movable between a scanning position and a rest position in which it is further away from the application device (16) compared to the scanning position, or in that the protective system (65) comprises a covering device with which the sensor unit (58) can be temporarily covered, a sealing air device with which the sensor unit (58) can be at least partially or completely flooded with a sealing air curtain, or a wiping device with which the sensor unit (58) can be freed of impurities that are detrimental to its function by wiping it off. [28] Application system according to one of claims 23 to 27, characterized by that one or more sensor units (58) are distributed in the room independently of the movement device (18). [29] Application system according to one of claims 15 to 28, characterized by that the movement device (18) is a multi-axis application robot (24) with a hand part (32) which carries the application device (16).

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