Device for compensating joining motions

Abstract

The invention relates to a joining unit (10, 40) for an articulated arm robot (12, 44) for joining a component (24, 58) with a joining element (28, 60) by applying an axial force. The joining unit (10, 40) comprises a base element (14, 42) for connecting to an articulated arm robot (12, 44). The base element (12, 42) is connected to an advancing unit (13, 46), which can be moved relative to the base element (14, 42) in an axial direction in and against a setting direction. The advancing unit (13, 46) is connected to a setting device (16, 54), which can be moved together with the advancing unit (13, 46). Furthermore, a pressure piece (26, 50) mounted for movement relative to the advancing unit (13, 46) in and against the setting direction is connected to the advancing unit (13, 46) by means of a coupling unit (17, 48). The invention is distinguished in that the coupling unit (17, 48) comprises a blocking unit (18, 56), which, starting from a predefined axial blocking position, prevents motion of the pressure piece (26, 50) relative to the advancing unit (13, 46) against the setting direction so long as the advancing force is less than the set blocking force. The blocking unit comprises a release device (20, 62), by means of which the relative motion of the pressure piece (26, 50) against the setting direction is enabled.

Claims

1. Joining unit (10, 40) for an articulated arm robot (12, 44) for joining a component (24, 58) with a joining element (28, 60) by applying an axial force, with the joining unit (10, 40) comprising a base element (14, 42) for connecting to an articulated arm robot (12, 44), which base element (14, 42) is connected to an advancing unit (13, 46) which can be moved relative to the base element (14, 42) in an axial direction in and against a setting direction, said advancing unit (13, 46) being connected to a setting device (16, 54) which can be moved together with the advancing unit (13, 46), with a pressure piece (26, 50) mounted for movement relative to the advancing unit (13, 46) in and against the setting direction being furthermore connected to the advancing unit (13, 46) by means of a coupling unit (17, 48), characterized in that the coupling unit (17, 48) comprises a blocking unit (18, 56) which, starting from a predefined axial blocking position, prevents movement of the pressure piece (26, 50) relative to the advancing unit (13), 46) against the setting direction so long as the advancing force is less than the set blocking force, which blocking unit comprises a release device (20, 62) by means of which the relative movement of the pressure piece (26, 50) against the setting direction is enabled.

2. Joining unit according to claim 1, characterized in that the blocking unit (18, 56) is designed such that the blocking force is constant.

3. Joining unit according to claim 1, characterized in that the blocking unit (18, 56) comprises a pneumatic cylinder (18, 56) or a hydraulic cylinder.

4. Joining unit according to claim 3, characterized in that the blocking unit (18, 56) comprises a valve, in particular a control valve or a pressure relief valve, which is connected to the cylinder.

5. Joining unit according to claim 3, characterized in that the release device comprises a bleed valve (20, 62).

6. Joining unit according to claim 1, characterized in that the blocking unit (18, 56) comprises an electric motor.

7. Joining unit according to claim 1, characterized in that the blocking unit (18, 56) acts directly on the pressure piece (26, 50).

8. Joining unit according to claim 1 characterized in that the blocking unit (18, 56) comprises a contact element which acts on the component (24, 58) to be joined.

9. Joining unit according to, claim 1 characterized in that the coupling unit (48) comprises a spring (52) which sets a base position of the pressure piece (50) relative to the advancing unit (46).

10. Joining unit according to, claim 1 characterized in that after actuation of the release device (20, 62), the advancing force acts on the joining element via the setting device (16, 54).

11. Joining unit according to, claim 1 characterized in that a placement contact detection means (25) is connected to the advancing unit (14) which detects the point in time when the joining element makes placement contact with the component (28), whereupon the release device (20) is actuated.

12. Joining unit according to claim 9, characterized in that the placement contact detection means (25) comprises a force sensor which is connected to the setting device (16, 54) and detects the axial process force acting on the setting device (16, 54).

13. Joining unit according to claim 9, characterized in that the placement contact detection means (25) operates via the drive of the advancing unit (14).

14. Joining unit according to, claim 1 characterized in that the setting device comprises a rotary spindle (16, 54).

15. Joining unit according to claim 14, characterized in that the rotary spindle is capable of producing a speed of between 3,000 and 10,000 revolutions per minute to produce a force-locking, a positive-locking or a material-locking connection, or a combination of the three.

16. Joining unit according to claim 14, characterized in that the setting device is guided through the pressure piece (26, 50), the pressure piece (26, 50) being of a hollow-cylindrical design.

17. Joining unit according to, claim 1 characterized in that the advancing force is maintained constant during the pretensioning operation and after actuation of the release device (20, 62).

18. Method for joining a component (24, 58) with a joining element (28, 60) using an articulated robot, with an advancing unit (13, 46) being provided on the articulated robot for axially introducing a joining element (28, 60) into the component (24, 58), the advancing unit (13, 46) comprising a setting device (16, 54) which can be fitted with a joining element (28, 60) and is moved toward the component (24, 58), with a releasable blocking device limiting the movement of the setting device (16, 54) relative to the component (24, 58) by means of a pressure piece (26, 50), so long as the applied advancing force is less than a preset blocking force, wherein the blocking device is released once the joining element (28, 60) makes placement contact, causing the advancing force equivalent to the blocking force to be transmitted via the setting device (16, 54) and the joining element (28, 60) and thus to the component (24, 58).

19. Method according to claim 18, characterized in that the pretensioning force equivalent to the the blocking force continues to act until the joining operation has been completed.

20. Method according to claim 18, characterized in that the advancing force is kept constant over the entire joining process.

21. Method according to any one of claim 18, characterized in that the method uses a joining unit as claimed in one of claims 1 to 17.

Description

[0032] Additional advantages, features and possible applications of this invention may be gathered from the description which follows, in which reference is made to the embodiments illustrated in the drawings. In the drawings,

[0033] FIG. 1 is a view of a first process step of a schematically illustrated arrangement according to the invention;

[0034] FIG. 2 is a view of a second process step of a schematically illustrated arrangement according to the invention;

[0035] FIG. 3 is a view of a third process step of a schematically illustrated arrangement according to the invention;

[0036] FIG. 4 is a view of a fourth process step of a schematically illustrated arrangement according to the invention;

[0037] FIG. 5 is a view of a first process step of another embodiment, according to the invention, of a schematically illustrated arrangement;

[0038] FIG. 6 is a view of a state after the first process step of the embodiment according to the invention;

[0039] FIG. 7 is a view of a second process step of another embodiment, according to the invention, of a schematically illustrated arrangement;

[0040] FIG. 8 is a view of a state after the second process step of the embodiment according to the invention; and

[0041] FIG. 9 is a view of a final state of the joining process of another embodiment, according to the invention, of a schematically illustrated arrangement.

[0042] The view of FIG. 1 shows a joining unit 10 according to the invention which is attached to a schematically illustrated articulated arm robot 12. The joining unit 10 has a base element 13 to which an advancing unit 14 is attached. The advancing unit 14 can be moved in the axial direction relative to the base element 13. A setting device in the form of a rotary spindle 16 is connected to the advancing unit 14. Furthermore, a coupling unit 17 is provided which acts parallel to the rotary spindle 16 and which couples a pressure piece 26 to the advancing unit 14. The coupling unit 17 comprises a blocking unit in the form of a pneumatic cylinder 18 connected to the advancing unit 14. The pneumatic cylinder 18 is fitted with a bleed valve 20 which acts as a release device and can be used to reduce the pressure applied to the piston 22 of the cylinder 18. At the end of the piston 22 facing a component 24, a pressure piece 26 is arranged which can be used to transmit a pressing force to the component 24. In the present embodiment, the blocking position from which on any relative movement of the pressure piece 26 below the blocking force is prevented, is permanently set to the maximum extension length of the piston 22. The distance of the pressure piece 26 from the advancing unit 14 is slightly higher than the distance of the tip of the joining element 28, which is fixed to the rotary spindle 16, from the advancing unit 14. In the present case, the blocking force is set to 2 kN. The pressure in the pneumatic cylinder 18 is set so that up to an applied force of 2 kN, it can be assumed that the pneumatic cylinder will behave rigidly. When the blocking force is reached, the compression of the air in the cylinder can cause the pressure piece 26 to move relative to the advancing unit 14. In addition, an initial placement contact detection means 25 is connected to the advancing unit 14 and the bleed valve 20.

[0043] As FIG. 2 further shows, this force is transmitted from the advancing unit 14 to the component 24. This pretensions the articulated arm robot 12, with the pressure piece 26 becoming offset with respect to the component 24 during this pretensioning process, depending on the angular positions of the articulated arm robot 12. In this way, pretension can be built up before the joining element 28 makes placement contact with the component 24.

[0044] The view of FIG. 3 shows another position in the setting process. In this phase of the joining process, the advancing unit 14 applies an advancing force that exceeds the blocking force of 2 kN. This compresses the fluid in the pressure chamber even though the connected bleed valve 20 is still closed. The compression of the fluid in the pressure chamber enables the pressure piece 26 to move relative to the advancing unit 14 until the tip of the joining element 28 comes to rest on the component 24. This is the time when the release device in the form of the bleed valve 20 will then be actuated.

[0045] The view of FIG. 4 shows the state occurring after opening the bleed valve 20. Opening the bleed valve 20 will cause the pressure chamber of the pneumatic cylinder 18 to be vented, with the result that no force can be transmitted between the component 24 and the articulated arm robot 12 via the pressure piece 26. As a consequence, the force is transmitted exclusively via the joining element 28 which is pressed onto the component 24 via the rotary spindle 16. This results in the joining element 28 being driven into the component 24 with an advancing force equal to the blocking force. Since there is an unchanged force ratio between the articulated arm robot 12 and the component 24, the process of setting the joining element 28 can be carried out without any offset during the joining process.

[0046] FIG. 5 is a schematic view of another embodiment of a joining unit 40 according to the invention. The joining unit 40 comprises a base element 42 which is fixed to an articulated arm robot 44. As described with reference to the figures above, the joining unit 40 comprises an advancing unit 46 which can be moved in the axial setting direction. Furthermore, a coupling device 48 is provided which connects a hollow cylindrical pressure piece 50 with the advancing unit 46. The coupling device 48 comprises a coil spring 52 that is arranged coaxially relative to the hollow cylindrical pressure piece 50 and to a rotary spindle 54 guided by the pressure piece 50. In addition, the coupling device 48 has a blocking unit which takes the form of a pneumatic cylinder 56. Similar to the embodiment illustrated in FIGS. 1 to 4, an initial placement contact detection means can also be integrated into the joining unit.

[0047] Contrary to the embodiment illustrated in FIGS. 1 to 4, the blocking position of the pressure piece 50 is not reached immediately when it is placed on the component or component assembly 58.

[0048] As shown in FIG. 5, the advancing unit 46 is moved towards the component assembly 58 in a first step until the pressure piece 50 makes contact with the component assembly 58. This position is shown in FIG. 6.

[0049] As shown in FIG. 7, in a second step once the pressure piece 50 has been placed on the component assembly 58, the advancing action of the advancing unit 46 causes the coil spring 52 to be compressed with respect to the component assembly 58 until the pneumatic cylinder 56 blocks any further relative movement of the pressure piece 50 in the direction of the advancing unit 46. Up to this position, only the spring force of the spring 52 acts on the pressure piece 50. Once the pressure piece has reached the blocking position and the pneumatic cylinder 56 exerts it preset blocking force, this force can be transmitted to the component assembly 58. Now, if the advancing unit acts with a force that is only slightly higher than the blocking force, this will cause the air volume in the cylinder 56 to be compressed further in a closed state of the bleed valve 62, until the joining element 60 comes to sit on the component assembly, as shown in FIG. 8.

[0050] The joining element 60 held in the rotary spindle 54 has its tip still above the component 58. The joining process is identical to the process described with reference to FIGS. 1 to 4. When the joining element makes contact during placement, which is detected by a force measuring device integrated in the advancing unit 46, a release device is actuated, which is designed as a bleed valve 62 in the present embodiment and which is vented to achieve release. This ensures complete and fast venting of the pneumatic cylinder 56, and the joining element 60 is driven into the component assembly 58 by rotating it and applying an axial force that roughly corresponds to the predefined blocking force, and in the present case connects the two component layers of the component assembly 58 with each other.

[0051] The view of FIG. 9 shows this final state with the cylinder 62 vented, in which the joining element 60 connects the two component layers of the component assembly 58.