Tool for robot-supported application of an adhesive tape to a surface

Abstract

The invention relates to a device for the robot-supported application of adhesive tape to a surface. According to one embodiment, the device comprises a frame (for example, a housing) and a receptacle for an adhesive tape roll having two support rollers (32, 33) mounted on the frame, a clamping roller (31) displaceably mounted on the frame, and a pretensioning device which is designed to exert a pretensioning force on the clamping roller (31) in the direction of the support rollers (32, 33). The device also comprises a first pressure roller (35) which touches the workpiece surface during the process of applying the adhesive tape.

Description

Tool for robot-assisted application of an adhesive tape to a surface TECHNICAL FIELD

[0001] The present invention relates to a robot-assisted taping tool, i.e. a tool for robot-assisted application of an adhesive tape to a surface. BACKGROUND

[0002] With increasing automation in production, a wide variety of tasks (e.g., sanding, polishing, painting, etc.) are performed by industrial robots. One of these tasks is the application of adhesive tape to surfaces, for example, when preparing a workpiece for a subsequent painting process. By masking off certain areas of the surface, these are protected during the painting process.

[0003] In many cases, the taping of surfaces is still done manually. However, there are already robot-mounted tools for dispensing adhesive tape. Known devices suitable for robots are similar to manually operated tools. The inventor has set himself the task of improving existing taping tool designs. SUMMARY

[0004] The above-mentioned object is achieved by the device according to claim 1. Different embodiments and further developments are the subject of the dependent claims.

[0005] The following describes a device for the robot-assisted application of adhesive tape to a surface. According to one exemplary embodiment, the device comprises a frame (e.g., a housing) and a holder for an adhesive tape roll with two support rollers mounted on the frame, a clamping roller displaceably mounted on the frame, and a pretensioning device designed to exert a pretensioning force on the clamping roller in the direction of the support rollers. The device further comprises a first pressure roller that contacts the workpiece surface during the adhesive tape application process. SHORT DESCRIPTION OF THE DRAWINGS

[0006] The invention is explained in more detail below using the examples shown in the figures. The illustrations are not necessarily to scale, and the invention is not limited to the aspects shown. Rather, emphasis is placed on illustrating the principles underlying the invention. The figures show:

[0007] Figure 1 shows an example of a system with a force-controlled linear actuator (mountable on an industrial robot) and a taping tool.

[0008] Figure 2 is a side view of a taping tool according to an embodiment with a mounted tape roll.

[0009] Figure 3 shows the taping tool with the tape on the tape roll almost used up.

[0010] Figures 4 and 5 show the easily removable mounting of the taping tool on the linear actuator, allowing easy replacement of the taping tools (for different strip widths) without having to dismantle the linear actuator from the robot.

[0011] Figure 6 illustrates in more detail the rollers shown in Figs. 2 and 3 that hold the tape roll and the measurement of the position of the clamp roller.

[0012] Figure 7 illustrates an example of the electronic circuit for measuring or detecting the position of the pinch roller in more detail. DETAILED DESCRIPTION

[0013] Fig. 1 shows, in perspective view, an example of a device comprising a force-controlled linear actuator 20 mountable on an industrial robot and a taping tool 30 for applying an adhesive tape to a surface of a workpiece with the aid of the industrial robot (not shown in the figures). The linear actuator acts between a (robot-side) carrier plate 11 and a (tool-side) carrier plate 12. The carrier plate 11 has a flange 10 that allows mounting of the pre- device on an industrial robot. During operation, the robot moves the device and thus the taping tool 30 along a specific trajectory (tool path). The linear actuator 20 bridges the variable distance between the support plates 11 and 12 and (as soon as the taping tool 30 touches a surface) exerts a controlled force on the taping tool 30, which presses against the surface while it (the linear actuator) is supported on the robot. The TCP (Tool Center Point) of the robot can be position-controlled and follows the aforementioned trajectory, while the linear actuator 20 controls the pressure force with which the taping tool presses against the surface.

[0014] The taping tool 30 is mounted on the carrier plate 12 (see also Fig. 4) and is thus connected to the robot only via the linear actuator 20. The linear actuator 20 thus ensures, on the one hand, a certain mechanical decoupling between the robot and the tool and, on the other hand, a constant process force during the application of the adhesive tape.

[0015] The taping tool 30 is shown in more detail in Fig. 2. The following explanations apply to both Fig. 1 and Fig. 2. The housing is essentially a frame 36 on which the other components of the taping tool 30 are mounted / supported. The frame 36 is not necessarily designed as a closed housing, although a closed design may be advantageous because the components arranged therein are protected from dust and other contaminants.

[0016] Three rollers 31, 32, and 33 are mounted on the frame 36 (in the housing), forming a holder for the adhesive tape roll 40. The rotational axes of the support rollers 32 and 33 are spaced apart from one another and have a fixed position relative to the frame 36. The axes (not shown) of the support rollers 32 and 33 are mounted inside the housing, for example, whereas the support rollers 32 and 33 are located outside on the housing wall. The clamping roller 31 has a linearly displaceable rotational axis. This means that the axis of the clamping roller 31 is mounted on the frame 36 (also inside the housing) in a linearly displaceable manner. In the example shown, the housing wall has a slot 360 through which the displaceably mounted axis of the clamping roller 31 is guided outwards. The linear guide for the axis of the clamping roller 31 is not shown, but suitable linear guides are known and commercially available and are therefore not explained in detail here.In the example shown, the direction of the linear movement of the clamping roller 31 is essentially perpendicular to the connecting line L between the. Rotation axes of the support rollers 32 and 33. The connecting line L also represents a plane in which the (parallel) rotation axes of the support rollers 32 and 33 lie. However, this is not necessarily the case, and angles other than right angles can also be provided.

[0017] The rollers 31, 32, and 33 lie essentially in a plane on the outside of the housing's outer wall. The clamping roller is preloaded, for example, with a spring 361. The direction of the spring force F is shown in Fig. 2. This means that the spring 361 pulls (or pushes, depending on the implementation) the clamping roller 31 toward the support rollers 32 and 33 (toward the connecting line L between the two support rollers 32, 33).

[0018] The three rollers 31, 32 and 33 serve to attach a roll 40 with adhesive tape 41 (adhesive tape roll) to the tool 30. The outer circumference of the adhesive tape roll 40 rests against the support rollers 32 and 33, while the clamping roller 31 rests against the inner circumference of the inner hole of the adhesive tape roll and holds it (due to the spring force). The adhesive tape 41 is guided around the support roller 32 (which also serves as a deflection roller) via the (optional) deflection roller 34 to the pressure roller 35, which is mounted on the lower end of the frame 36. The pressure roller 35 presses the adhesive tape 41 against the surface O of a workpiece so that the adhesive tape 41 adheres to the surface O. A further (optional) pressure roller 39 can improve the adhesion of the adhesive tape 41 to the surface. The further pressure roller 39 and the deflection roller 34 are also mounted on the frame 36 with a fixed axis of rotation relative to the frame 36.

[0019] The pressure roller 35 can be mounted on a pivotable part of the frame 36. In the example shown, this pivotable part is the bracket 362, which is pivotally mounted about a rotation axis. In the example shown in Figs. 2 and 3, the rotation axis of the bracket 362 is coaxial with the rotation axis of the deflection roller 34 (although this does not necessarily have to be the case). The angle 0=0i shown in Fig. 2 represents the position of the bracket 362 relative to the remaining part of the frame 36. The bracket 362 can be pivoted by means of a linear actuator 362 from a first angular position 0i to a second (retracted) angular position 0o. In the example shown, the linear actuator 362 is a small pneumatic cylinder. However, electromechanical actuators are also possible. The angular positions 0o and 0i can be set, for example, by end stops. be defined. During the application of adhesive tape to a surface (taping process), the bracket 362 and thus the pressure roller 35 are in the extended position (angular position 0i). The bracket 362 can be fixed in this position, so that the pressure force between the pressure roller 35 and the surface of the workpiece is essentially determined by the actuator force of the actuator 20 (see Fig. 1).

[0020] It is understood that the construction shown in Figs. 1 and 2 is merely one of many possible implementations. The pressure roller 35 is not necessarily mounted on a pivotable bracket, but in other embodiments can also be fixedly mounted on the frame 36. The pressure roller 39 is optional and is not required in other embodiments. The deflection roller 34 is also optional. However, the construction shown in Figs. 1 and 2 has the advantage that the tool path along which the robot moves the taping tool 30 does not have to be precisely matched to the workpiece. Variations in the distance between the robot's TCP and the surface can be compensated for by the linear actuator 20. Due to the force control, the linear actuator 20 will always press the pressure roller 39 onto the surface O of the workpiece with a defined force, regardless of the deflection of the linear actuator.

[0021] To cleanly cut the adhesive tape 41, the taping tool 30 can have a blade 38. The blade 38 is positioned such that it cuts the tape when the bracket 362 (including the pressure roller 35) is moved from the angular position 0i to the (retracted) angular position 0o. In Fig. 3, the pressure roller 35 in the retracted position is designated 35'. Before cutting the adhesive tape 41 with the blade 38, the robot can position (tilt) the taping tool 30 such that the pressure roller 39 rests on the surface and the pressure roller 35 is slightly lifted from the surface O of the workpiece. The bracket 362 is then moved to the position 0o with the aid of the actuator 363, whereby the tape is cut.

[0022] Due to the movable nature of the clamping roller 31, the holder for the adhesive tape roll 41 is suitable for rolls of various sizes. The diameter of the inner hole of the roll 40 can also be within a relatively large range. The outer diameter of the roll 40 decreases as the adhesive tape 41 is unwound. Fig. 3 shows the same A device like Fig. 2, but with an almost used up adhesive tape roll 40, whereas in Fig. 2 the adhesive tape roll 40 is new. The position of the clamping roller 31 (relative to the frame 36) is a measure of how much tape is (still) on the roll 40. Starting from a new roll 40 and with a known tape thickness, the change in the position of the clamping roller 31 is a measure of how much tape has already been unwound. In the illustrated embodiments, the position and / or the change in the position of the clamping roller 31 can be evaluated in order to detect that the tape is running low. Shortly before the tape is completely unwound, a signal can be transmitted to the robot control which causes it to interrupt the current process (in a controlled and defined manner) in order to load the taping tool 30 with a new adhesive tape roll. The process can then be continued.

[0023] With known systems, there is often the problem that the robot controller does not "know" that the tape is running low. Therefore, it can happen that the tape ends at some undefined point during the process and the process cannot be continued without further ado after a change of the roll 40 because the robot controller has no information about where exactly the tape ran out. The special design of the holder for the adhesive tape roll 40 and the measurement of the position of the clamping roller 31 (and the monitoring of the change in position) allow this problem to be avoided. The measurement of the position of the clamping roller 31 will be explained in more detail later with reference to Fig. 6. The electronic circuit 5, which is arranged on a printed circuit board in the housing 36 and is used for measuring or detecting the position of the clamping roller 32, is shown schematically in Fig. 3 (see also Fig. 7).

[0024] According to the embodiment shown in Fig. 4, the taping tool 30, in particular the frame 36, is attached to the carrier plate 12 in an easily detachable manner. This modular design enables simple replacement of the taping tool 30. Different taping tools 30 for different tape widths can be kept in stock, and a tool change is possible without having to disassemble the linear actuator 20 from the robot. In the example shown, only two screws are required to attach the taping tool 30 to the carrier plate 12. Alternatively, other types of attachment can be used, for example, quick-release fasteners or the like. Fig. 5 shows different taping tools 30 for adhesive tape rolls 40 of different widths. The electronic circuit board 5 (see Fig. 3) can be connected by a cable to a connector, which can be connected, for example, to the carrier plate 11 (see Fig. 4) of the device. The taping tool 30 can optionally also have a compressed air connection to supply the actuator 363 (see Fig. 2) with compressed air.

[0025] Fig. 6, diagrams (a) and (b) illustrate the rollers 31-33 shown in Figs. 2 and 3, which hold the adhesive tape roll 40, as well as the measurement of the position a=ao+Aa of the clamping roller 31 in more detail. Also shown in Fig. 6 is the mounting of the rollers 31-33 on the frame 36 (housing), wherein the support rollers 32 and 33 have a fixed axis of rotation with respect to the frame 36 and the clamping roller 31 is slidably mounted on the frame 36. The axis of rotation of the clamping roller 31 is displaceable in one direction; in the example shown, the direction of displacement is perpendicular to the connecting line L, which connects the axes of rotation of the other two rollers 32 and 33.

[0026] The adhesive tape roll is shown in dashed lines in Fig. 6. The diameter of the inner hole of the adhesive tape roll 40 is Di, and the outer diameter of a new adhesive tape roll 40 is Do. The force F, which presses the clamping roller 31 against the inner circumference of the adhesive tape roll 40, is also shown in Fig. 6. Diagram (a) of Fig. 6 shows the clamping roller 31 in a first position a=ao, which corresponds to a new adhesive tape roll 40. Of course, the position ao depends on the diameters Di and D o where the diameter D o depends in particular on the thickness of the wound adhesive tape 41 and the number of windings.

[0027] Diagram (b) of Fig. 6 shows the clamping roller 31 in a second position a=ao-Aa, which corresponds (approximately) to a used-up roll of adhesive tape 40. During a process for applying the adhesive tape 41 to a surface, the value Aa becomes increasingly larger (and the deflection a smaller). By measuring (see Fig. 7, displacement sensor 51) the position change Aa, it is possible to recognize that the tape will soon be used up, even without knowing the total length of the wound-up tape at the beginning of the process. Holding the adhesive tape roll 40 by three rollers also makes it possible for the device to be suitable for different sizes (in particular different inner diameters Di) of the adhesive tape roll 40. In some embodiments, one of the rollers 31-33, for example the support roller 32 or the deflection roller 34, can be equipped with a speed sensor (rotary encoder or the like, see Fig.7, encoder 53) to detect whether the respective roller is rotating. The rotational speed does not need to be measured; simply detecting whether the respective roll is rotating or not is sufficient. Such detection also allows for rapid error detection during a taping process. For example, the adhesive tape 41 may tear. In this case, no more tape is unwound from the adhesive tape roll 40, and the rolls 31-34 stop rotating.

[0028] Fig. 7 illustrates a simplified block diagram of the electronics 5, which can be arranged on a circuit board inside the housing 36. In the example shown, a displacement sensor 51 is provided, which is designed to measure the position a of the clamping roller 31. A potentiometer or a capacitive or inductive sensor, for example, can be used as a displacement sensor. The sensor signal u(Aa), which is fed to the controller circuit 50, represents the value a or Aa. The controller circuit 50 can, for example, have an analog-to-digital converter that digitizes the sensor signal u(Aa).

[0029] However, it is not absolutely necessary to measure the position a of the clamping roller 31. It may also be sufficient to detect that the clamping roller 31 is approaching or reaching the second position (end position, see Fig. 3). In these cases, a proximity sensor, a light barrier or the like can be used instead of a displacement sensor. In this case, the sensor signal u merely indicates that the clamping roller 31 has reached a defined position. Also shown in Fig. 7 is the (optional) rotary encoder 52 (speed sensor), which is designed to detect whether, for example, the roller 32 is actually rotating. If the speed is zero during a taping process (co=0), it can be concluded that the adhesive tape 41 has torn or, for other reasons, is not being correctly unwound and applied to the surface O.

[0030] Depending on the sensor signal u, the controller circuit 50 can inform the robot controller or process controller that the tape is running low and will soon run out. Based on this information, the robot controller or process controller can initiate certain actions, for example, moving the taping tool 30 to a defined maintenance position where the empty tape roll 40 can be replaced, and then continuing the process. The controller circuit 50 can, for example, A bus line 52 can be connected to a higher-level controller (e.g., the robot controller). For this purpose, the controller circuit 50 can, for example, have a CAN (Controller Area Network) bus interface.

Claims

PATENT CLAIMS 1. A device for applying adhesive tape to a surface, the device comprising the following: a frame (36); a holder for a roll of adhesive tape (40) with two support rollers (32, 33) mounted on the frame (36), a clamping roller (31) displaceably mounted on the frame (36), and a pretensioning device (361) which is designed to exert a pretensioning force (F) on the clamping roller (31) in the direction of the support rollers (32, 33); and a first pressure roller (35, 39) which contacts the workpiece surface (O) during the process of applying the adhesive tape (41).

2. The device according to claim 1, wherein the support rollers (32, 33) have axes of rotation which are fixed with respect to the frame (36).

3. The device according to claim 1 or 2; wherein the clamping roller (31) has a rotation axis that is displaceable with respect to the frame (36).

4. The device according to claim 1 or 2, wherein the support rollers (32, 33) have axes of rotation which are stationary with respect to the frame (36), wherein the axes of rotation of the support rollers (32, 33) lie in a plane (L), and wherein the clamping roller (31) has an axis of rotation which is displaceable with respect to the frame (36) in a direction which is perpendicular to the plane (L).

5. The device according to one of claims 1 to 4, further comprising: a first sensor (51) adapted to measure the position (ao-Aa) of the rotational axis of the clamping roller (31) with respect to the frame (36) or the change (Aa) of the position of the rotational axis of the clamping roller (31).

6. The device according to one of claims 1 to 5, wherein, when an adhesive tape roll (40) is inserted into the receptacle, an outer circumference of the adhesive tape roll (40) rests against the support rollers (32, 33) and the clamping roller (31) presses against an inner circumference of an inner hole of the adhesive tape roll (40).

7. The device according to one of claims 1 to 6, wherein in operation the adhesive tape (41) is guided from the adhesive tape roll (40) via at least one deflection roller (34) to the first pressure roller (35).

8. The device according to one of claims 1 to 7, further comprising: a second pressure roller (39) fixedly mounted on the frame (36).

9. The device according to claim 8, wherein in operation the second pressure roller (39) is located behind the first pressure roller (35) in the direction of movement.

10. The device according to one of claims 1 to 9, further comprising: a blade (38) mounted on the frame (36), wherein the pressure roller (35) is mounted on a pivotable bracket (362) of the frame (36), and wherein, when the bracket (361) is pivoted towards the blade (38), the blade cuts off an adhesive tape (41) resting on the pressure roller (35).

11. The device according to claim 10, further comprising: an actuator (363) mounted on the frame (36) so as to retract and extend the pivotable bracket (362) with respect to the rest of the frame (36).

12. The device according to one of claims 1 to 11, further comprising: a second sensor (53) coupled to the clamping roller (31) or to one of the support rollers (32, 33) and configured to detect whether the respective roller is rotating.

13. The device according to claim 7, further comprising: a second sensor (53) coupled to the deflection roller (34) and configured to detect whether the deflection roller (34) is rotating.

14. The device according to one of claims 1 to 13, further comprising: a first support plate (11) with a flange (10) for mounting on a robot; a second support plate (12); and a linear actuator (20) arranged between the first support plate (11) and the second support plate (12); wherein the frame (36) is mounted on the second support plate (12) and detachably connected thereto.

15. The device according to any one of claims 5 and 12 to 13, as dependent on claim 5, further comprising: an electronic circuit (5) configured to receive a position signal generated by the first sensor (51) and to detect based thereon that the adhesive tape (41) on the adhesive tape roll (40) is running low.

16. The device according to claim 15, wherein the electronic circuit (5) is designed to receive a signal generated by the second sensor (53) and to detect an error based thereon, in particular to detect that the adhesive tape (41) is not unwound.

17. The device according to claim 15 or 16, wherein the electronic circuit (5) is designed to communicate with a higher-level controller, in particular a robot controller, by means of a data bus.

18. A device for applying adhesive tape to a surface, the device comprising: a frame (36); a holder for a roll of adhesive tape (40) with two support rollers (32, 33) mounted on the frame (36), a clamping roller (31) displaceably mounted on the frame (36), and a pretensioning device (361) which is designed to exert a pretensioning force (F) on the clamping roller (31) in the direction of the support rollers (32, 33); a first pressure roller (35, 39) which contacts the workpiece surface (O) during the process of applying the adhesive tape (41); and a first sensor (51) which is designed to measure the position (ao-Aa) of a rotational axis of the clamping roller (31) relative to the frame (36) or the change (Aa) in the position of the rotational axis of the clamping roller (31).

19. The apparatus of claim 18, further comprising: an electronic circuit (5) configured to receive a position signal generated by the first sensor (51) and to detect, based thereon, that the adhesive tape (41) on the adhesive tape roll (40) is running low.

20. The device according to claim 18 or 19, further comprising: a second sensor (53) coupled to the clamping roller (31) or to one of the support rollers (32, 33) and configured to detect whether the respective roller is rotating.

21. The device according to claim 18 or 19, wherein, in operation, the adhesive tape (41) is guided from the adhesive tape roll (40) via at least one deflection roller (34) to the first pressure roller (35); and wherein the device comprises a second sensor (53) coupled to the deflection roller (34) and configured to detect whether the deflection roller (34) is rotating.

22. The device according to claim 20 or 21, as dependent on claim 2, wherein the electronic circuit (5) is designed to receive a signal from the second sensor (53) and to detect an error based thereon, in particular to detect that the adhesive tape (41) is not unwound.

23. The device according to claim 19 or 22, wherein the electronic circuit (5) is designed to communicate with a higher-level controller, in particular a robot controller, by means of a data bus.

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