JOINING APPARATUS

Abstract

A joining apparatus for the joining of a joining element to a workpiece on a joining surface, the joining apparatus comprising: a joining head that defines a joining axis; a cleaning device for cleaning the joining surface; and a drive unit for moving the cleaning device in relation to the joining head between a waiting position and a cleaning position. The waiting position axially rearward and transversely spaced from a holding device forwardmost on the joining head; and the cleaning position axially forward and transversely closer to the holding device

Claims

1. A joining apparatus for the joining of a joining element to a workpiece on a joining surface, the joining apparatus comprising: a joining head that defines a joining axis, a cleaning device for cleaning the joining surface, and a drive unit for moving the cleaning device in relation to the joining head between a waiting position (WP) and a cleaning position (RP).

2. The joining apparatus according to claim 1, wherein the drive unit is fixed to the joining head.

3. The joining apparatus according to claim 1, wherein the drive unit comprises a linear drive.

4. The joining apparatus according to claim 3, wherein the linear drive comprises a pneumatic cylinder.

5. The joining apparatus according to claim 3, wherein the cleaning device further comprises a housing that is coupled to the linear drive.

6. The joining apparatus according to claim 1, wherein the drive unit comprises a constraining guide for the cleaning device, whereby the cleaning device is moveable on a defined path between the waiting position (WP) and the cleaning position (RP) by means of the constraining guide.

7. The joining apparatus according to claim 6, wherein the constraining guide is shaped to guide cleaning device parallel to the joining axis in some portions of a path between the waiting position and the cleaning position.

8. The joining apparatus according to claim 6, wherein the constraining guide is shaped to guide the cleaning device transversely to the joining axis in some portions of a path between the waiting position and the cleaning position.

9. The joining apparatus according to claim 6, wherein the constraining guide is shaped to guide the cleaning device so that, starting from the waiting position (WP), the cleaning device is first guided parallel to the joining axis, then transversely to the joining axis, and finally again parallel to the joining axis towards the cleaning position (RP).

10. The joining apparatus according to claim 6, wherein the constraining guide comprises a gate slot, which is connected to the joining head, and wherein the constraining guide includes a gate follower connected to the cleaning device and engages the gate slot for movement therein.

11. The joining apparatus of claim 10, wherein the gate slot comprises a serpentine track including a first longitudinal portion and a bend portion.

12. The joining apparatus according toclaim, wherein the gate follower comprises a front gate follower and a rear gate follower spaced axially apart from one another on the cleaning device in a direction substantially parallel to the joining axis and engaging in the gate slot.

13. The joining apparatus according to claim 12, wherein the front gate follower or the rear gate follower is formed by at least one of rollers or bearings.

14. The joining apparatus according to claim 12, wherein an axial spacing between the front gate follower and the rear gate follower is less than a longitudinal extent of a first longitudinal portion of the gate slot.

15. The joining apparatus according to claim 12, wherein an axial spacing between the front gate follower and the rear gate follower is greater than one of (i) a longitudinal extent of a bend portion of the gate slot or (ii) a longitudinal extent of a second longitudinal portion of the gate slot.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Exemplary embodiments of the invention are shown in the drawing and will be explained in more detail in the following description. In the drawing:

[0058] FIG. 1 shows a perspective view of a joining apparatus.

[0059] FIG. 2 shows the joining apparatus of FIG. 1 in a waiting position.

[0060] FIG. 3 shows the joining apparatus of FIG. 1 in a first position between the waiting position and a cleaning position.

[0061] FIG. 4 shows the joining apparatus of FIG. 1 in a second position between the waiting position and the cleaning position.

[0062] FIG. 5 shows the joining apparatus of FIG. 1 in a third position between the waiting position and the cleaning position.

[0063] FIG. 6 shows the joining apparatus of FIG. 1 in a fourth position between the waiting position and the cleaning position.

[0064] FIG. 7 the joining apparatus of FIG. 1 in the cleaning position.

[0065] FIG. 8 a front view along the joining axis of the joining apparatus of FIG. 1.

[0066] FIG. 9 a joining apparatus according to the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] In FIG. 1, a joining apparatus is shown in perspective and is denoted generally by 10.

[0068] The joining apparatus 10 includes a joining arrangement 12 (joining head), which is guided, for example, by means of a robot 14 and for this purpose is fixed to an arm 16 of the robot 14.

[0069] A carriage 18 is moveable on the joining arrangement 12 along a joining axis 20. The carriage 18 includes a holding device 22, which is designed to hold a joining element 24 (shown schematically in FIG. 1). A mouthpiece 25 is also provided. The mouthpiece 25 is arranged around the holding device 22. The holding device 22 can move along the joining axis 20 independently of the mouthpiece 25.

[0070] For example, the joining arrangement 12 can be in the form of a stud welding arrangement. In an exemplary stud welding process, the joining arrangement 12 is positioned above a component. The carriage is then actuated so that the joining element 24 held in the holding device 22 contacts the component (see FIG. 9). The mouthpiece 25 also contacts the component. A pilot current is then switched on and flows over the component and the joining element. The joining element is then lifted off so that an electric arc is drawn (the mouthpiece 25 remains in contact with the component during this step). The current is then increased to melt the oppositely arranged joining surfaces (see FIG. 9). The stud is then lowered back onto the component by means of the carriage. The current is switched off. The mixed melts of the joining element and the component cool down and the joining element (stud) is welded to the component.

[0071] In some cases, it is useful to clean the joining surface of the component (see reference sign 130 in FIG. 9) before such a joining operation, especially if the joining surface is covered with a coating.

[0072] To this end, the joining apparatus 10 comprises a cleaning device 34 attached to the joining arrangement 12.

[0073] The cleaning device 34 defines an application axis 36 oriented at an angle α with respect to the joining axis 20. However, the application axis 36 can also be oriented parallel to the joining axis 20.

[0074] Furthermore, a detection device 38 is fixed to the joining arrangement 12 and can, for example, detect a surface condition of the component in a manner similar to that described with respect to FIG. 9. The detection device 38, however, is provided optionally.

[0075] The cleaning device 34 includes a nozzle-type applicator 40 having an applicator tip 42. The applicator 40 is, for example, a plasma nozzle (or a plasma torch).

[0076] The joining apparatus 10 further includes a drive unit 44 for moving the cleaning device 34 between a waiting position WP and a cleaning position RP. The drive unit 44 includes a linear drive 46, which can be formed in particular by a pneumatic cylinder 47.

[0077] The cleaning device 34 includes a housing 48, which is oriented generally parallel to the longitudinal axis 20, with the applicator 40 and applicator tip 42 disposed at the forward end of said housing.

[0078] The housing 48 is displaceable between the waiting position and the cleaning position by means of a constraining guide 50 (gate). For this purpose, the housing 48 is coupled to the pneumatic cylinder 47, either rigidly or in an articulated fashion.

[0079] The constraining guide 50 includes a gate slot 52, which is formed on a component of the drive unit 44 that is fixed to the joining arrangement 12. The gate slot 52 extends generally parallel to the joining axis 20.

[0080] A first gate follower 54 and a second gate follower 54 are fixed to the housing 48, axially spaced apart from one another, and each engage in the gate slot 52.

[0081] This allows the housing 48 of the cleaning device 34 to be forcibly guided along the gate slot 52.

[0082] The cleaning device 34 is usually in the waiting position WP shown in FIG. 1. This means that the applicator tip is arranged comparatively behind the holding device 22 and away from the joining axis 20, so that the cleaning device 34 does not interfere with the actual joining process.

[0083] If the joining surface of the component onto which the joining element 24 is to be joined is to be cleaned, the cleaning device 34 is moved, before the joining process, into the cleaning position, in which the applicator tip is guided in the axial direction in front of the holding device 22 (and in front of the mouthpiece 25), and in particular also closer to the joining axis 20.

[0084] This transition from the waiting position WP to the cleaning position RP is shown in FIGS. 2 to 7.

[0085] FIG. 2 shows the waiting position WP. In this position of the cleaning device, the applicator tip 42 is a distance y.sub.0 away from the joining axis 20. The value of y.sub.0 can lie in a range of from 1 cm to 8 cm, for example.

[0086] In FIG. 2, the applicator tip 42 is additionally positioned axially behind the front end of the mouthpiece 25 of the joining arrangement 12. The mouthpiece 25 is often placed on the component during the joining process, for example to introduce a protective gas or the like.

[0087] FIG. 2 further shows that the gate slot 52 has a first longitudinal portion 56, a bend portion 58, and a second longitudinal portion 60.

[0088] In the waiting position WP, the rear gate follower 54 abuts a rear end of the first longitudinal portion 56. The front gate follower 54 (the right-hand gate follower in FIG. 2) lies inside the first longitudinal portion 56. The bend portion is formed in the manner of an offset and connects the first longitudinal portion 56 and the second longitudinal portion 60. The bend portion 58 defines an offset value y.sub.s in the transverse direction between the first longitudinal portion 56 and the second longitudinal portion 60. The offset value y.sub.s is less than or equal to the value of y.sub.0.

[0089] In FIG. 2, the waiting position WP is shown, in which the rear gate follower 54 is located at the rear end of the gate slot 52, more specifically in a position x.sub.0.

[0090] The bend portion 58 has an axial extent that is smaller than the axial extent of the first longitudinal portion 56. Similarly, the second longitudinal portion 60 has a longitudinal extent that is smaller than that of the first longitudinal portion 56. The ratio of the longitudinal extents of the longitudinal portions 56, 60 may, for example, be in a range from 2:1 to 8:1.

[0091] The bend portion 58 is approximately as long in the axial direction as the second longitudinal portion 60.

[0092] Starting from the waiting position WP of FIG. 2, the linear drive 46 is controlled to displace the housing 48, specifically along a defined path determined by the constraining guide 50.

[0093] In FIG. 3, a first position x.sub.1 is shown, in which the rear gate follower 54 has moved away from the initial position x.sub.0. The front gate follower 54 is still located within the first longitudinal portion 56. Consequently, the cleaning device 34 is displaced substantially parallel to the joining axis 20 in this first phase. The distance y.sub.1 shown in FIG. 3 between the applicator tip 42 and the joining axis 20 is therefore substantially equal to the distance y.sub.0 shown in FIG. 2. In FIG. 3, the applicator tip 42 is positioned in a position in front of the mouthpiece 25.

[0094] FIG. 4 shows a subsequent position, in which the rear gate follower 54 has reached a position x.sub.2. The front gate follower 54 has entered the bend portion 58. Consequently, a distance y.sub.2 is established between the applicator tip 42 and the joining axis 20 and is preferably smaller than the distance y.sub.0.

[0095] In FIG. 4, the applicator tip is positioned even further forward of the mouthpiece 25.

[0096] In FIG. 5, a subsequent position x.sub.3 is shown, in which the front gate follower 54 is still located in the bend portion 58. It can be seen that the applicator tip 42 has been moved even closer to the joining axis 20 (y.sub.3 smaller than y.sub.2).

[0097] In FIG. 6, a position is shown in which the front gate follower 54 has reached the second longitudinal portion 60, i.e. has left the bend portion 58.

[0098] Here, the distance between the applicator tip 42 and the joining axis 20 is further reduced to a value y.sub.4, which is smaller than y.sub.3.

[0099] The rear gate follower 54 is still located within the first longitudinal portion 56 in an axial position x.sub.4.

[0100] Consequently, as the front gate follower 54 moves within the bend portion 58, the housing 48 of the cleaning device 34 has undergone a form of pivoting movement around the rear gate follower 54, which is superimposed on the longitudinal movement.

[0101] In FIG. 7, the cleaning position RP is shown, in which the front gate follower 54 is located at the end of the second longitudinal portion 60, i.e. has abutted against the front end of the gate slot 52. Here, a distance y.sub.5 is still established between the applicator tip 42 and the joining axis 20 and is substantially equal to the distance y.sub.4, since the front gate follower 54 has moved substantially along the second longitudinal portion between the illustration of FIG. 6 and the illustration of FIG. 7.

[0102] In the cleaning position RP shown in FIG. 7, it is possible to selectively apply a cleaning medium by means of the applicator 40 to a joining surface oriented centrally relative to the joining axis 20, more specifically to apply a cleaning medium preferably obliquely at an angle α which can be less than or equal to 90°, in this case less than 90°. The cleaning medium is, for example, plasma. The applicator 40 shoots a plasma jet onto the surface to be cleaned.

[0103] Consequently, for a joining process, it is first possible to position the joining axis 20 of the joining arrangement centrally above the joining surface of the component (reference sign 130 in FIG. 9), for example by means of a robot. Subsequently, the cleaning device 34 can first be moved from the waiting position WP into the cleaning position RP. Then, the cleaning process can be carried out. The cleaning device can then be retracted back into the waiting position WP. The joining process described above can then be carried out preferably solely by means of the carriage. Consequently, a repositioning of the joining arrangement is not absolutely necessary after the cleaning process.

[0104] FIG. 8 shows a plan view of the joining apparatus 10 in the waiting position WP, in which it can be seen that the applicator tip 42 is spaced apart from the joining axis 20 by the distance y.sub.0 in the transverse direction.

TABLE-US-00001 LIST OF REFERENCE SIGNS: 10 joining apparatus 12 joining arrangement / joining head 14 robot 16 arm 18 carriage 20 joining axis 22 holding device 24 joining element 25 mouthpiece 34 cleaning device 36 application axis 38 detection device 40 applicator (nozzle) 42 applicator tip 44 drive unit 46 linear drive 47 pneumatic cylinder 48 cleaning device housing 50 constraining guide / gate 52 gate slot 54 gate follower / rollers 56 first longitudinal portion 58 bending portion 60 second longitudinal portion 110 joining apparatus 112 joining head 114 robot 116 arm 118 carriage 120 joining axis 122 holding device 124 joining element 126 joining surface 128 component/metal sheet 130 second joining surface 132 coating 134 cleaning device 136 longitudinal axis 138 detection device WP waiting position RP cleaning position α angle ys offset value of slot 52