Holding device for holding a stud and joining head

Abstract

A device for holding a stud with a radially flange and an axial shank. The holding device comprising a collet including a clamping section and a hollow insertion section defining an insertion axis such that the stud can be inserted via the insertion section to the clamping section. The holding device further comprising a tubular securing sleeve located radially inward of and concentric with the insertion section. A clearance is defined between a bottom end of the securing sleeve and a top end of the clamping section and is adapted to releasably receive the stud flange. A first air flow channel in a first direction is adapted to blow feed the stud into the collet; and a second airflow channel oriented in a second different direction is adapted to maintain the stud shank substantially in line with the insertion axis.

Claims

1. A holding device for holding a stud which includes a radially projecting flange and a shank defining a stud axis, the holding device comprising: a collet component defining an insertion axis and including a clamping section and an insertion section and a first tapered section located between the clamping section and the insertion section and adapted to receive the stud such that the stud can be inserted via the insertion section to the clamping section, the clamping section adapted to exert a radially inwardly directed clamping force for clamping the stud; a securing device substantially tubular and located radially inward of and concentric with the insertion section and comprising a securing sleeve axially fixed relative to the collet component; a clearance space defined between a bottom end of the securing sleeve and a top end of the clamping section, the clearance space adapted to releasably receive the flange of the stud; a first air flow channel adapted to blow feed the stud into the collet component, the first air flow channel oriented in a first direction; a second airflow channel oriented in a second direction different from the first direction, the second air flow channel adapted to maintain the stud axis substantially in line with the insertion axis; and wherein the securing sleeve includes a first component and a second component at least partially located radially inward of the first component, and wherein the second air flow channel is partially defined between the first and second components.

2. A holding device according to claim 1, wherein the collet component includes a slotted cylindrical front portion forming the clamping section.

3. A holding device according to claim 1, wherein the first tapered section includes a first inner surface, and the clamping section includes a clamping inner surface, and the first inner surface is inclined to the clamping inner surface at an angle (?) of between 30 degrees and 55 degrees.

4. A holding device according to claim 3, wherein the first inner surface is inclined to the clamping inner surface at an angle (?) of 40 degrees.

5. A holding device according to claim 3, wherein the collet component includes a second tapered section located between the clamping section and the insertion section, the second tapered section including a second inner surface inclined to an inner surface of the insertion section, and the second tapered section is located between the first tapered section and the insertion section.

6. A holding device according to claim 1, wherein the first tapered section includes a first inner surface, and the first inner surface includes a radius of curvature, the radius of curvature allowing a correct positioning of the stud.

7. A holding device according to claim 1, wherein the securing sleeve includes a slot, and the slot forms the second airflow channel.

8. A holding device according to claim 7, wherein the slot is an annular slot and includes an inlet and an outlet adapted to discharge an air inside the securing sleeve.

9. A holding device according to claim 1, wherein the first component has a radially projecting first flange, wherein the second component has a radially projecting second flange, wherein the first flange is arranged axially facing the second flange such that a space is partially defined between the first and second flanges, and the space forms a portion of the second air flow channel.

10. A holding device according to claim 1, wherein the first component includes a first cylindrical body, and the second component includes a second cylindrical body extending coaxially inside the first cylindrical body, and a radial gap is partially defined between the first and second cylindrical body, such that the gap forms a portion of the second air flow channel.

11. A holding device according to claim 1, wherein one of the first component and the second component includes a sealing element.

12. A holding device for holding a stud which includes a radially projecting flange and a shank defining a stud axis, the holding device comprising: a collet component defining an insertion axis and including a clamping section and an insertion section and a first tapered section located between the clamping section and the insertion section and adapted to receive the stud such that the stud can be inserted via the insertion section to the clamping section, the clamping section adapted to exert a radially inwardly directed clamping force for clamping the stud; a securing device substantially tubular and located radially inward of and concentric with the insertion section and comprising a securing sleeve axially fixed relative to the collet component; a clearance space defined between a bottom end of the securing sleeve and a top end of the clamping section, the clearance space adapted to releasably receive the flange of the stud; a first air flow channel adapted to blow feed the stud into the collet component, the first air flow channel oriented in a first direction; a second airflow channel oriented in a second direction different from the first direction, the second air flow channel adapted to maintain the stud axis substantially in line with the insertion axis; and wherein the securing sleeve includes a slot, and the slot forms the second airflow channel, and wherein the slot is an annular slot and includes an inlet and an outlet adapted to discharge an air inside the securing sleeve.

13. A holding device according to claim 12, wherein the collet component includes a slotted cylindrical front portion forming the clamping section.

14. A holding device according to claim 12, wherein the first tapered section includes a first inner surface, and the clamping section includes a clamping inner surface, and the first inner surface is inclined to the clamping inner surface at an angle (?) of between 30 degrees and 55 degrees.

15. A holding device according to claim 14, wherein the first inner surface is inclined to the clamping inner surface at an angle (?) of 40 degrees.

16. A holding device according to claim 14, wherein the collet component includes a second tapered section located between the clamping section and the insertion section, the second tapered section including a second inner surface inclined to an inner surface of the insertion section, and the second tapered section is located between the first tapered section and the insertion section.

17. A holding device according to claim 12, wherein the first tapered section includes a first inner surface, and the first inner surface includes a radius of curvature, the radius of curvature allowing a correct positioning of the stud.

18. A holding device according to claim 12, wherein the securing sleeve includes a first component and a second component at least partially located radially inward of the first component, and wherein the second air flow channel is partially defined between the first and second components.

19. A holding device according to claim 18, wherein the first component has a radially projecting first flange, wherein the second component has a radially projecting second flange, wherein the first flange is arranged axially facing the second flange such that a space is partially defined between the first and second flanges, and the space forms a portion of the second air flow channel.

20. A holding device according to claim 18, wherein the first component includes a first cylindrical body, and the second component includes a second cylindrical body extending coaxially inside the first cylindrical body, and a radial gap is partially defined between the first and second cylindrical body, such that the gap forms a portion of the second air flow channel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other characteristics and advantages of the invention will readily appear from the following description of embodiments, provided as non-limitative examples, in reference to the accompanying drawings.

(2) FIG. 1 shows a cross-section of a holding device according to the invention having a collet component, a securing device and a clearance space defined between a bottom end of the securing sleeve and a top end of the clamping section, with a stud arranged in the holding device in a ready position, in which the shank axis of the stud is coincident with an insertion axis.

(3) FIG. 2 is a detailed view of a portion of the collet component and the stud of FIG. 1.

(4) FIG. 3 shows a cross-section of a joining head with the holding device and the stud of FIG. 1 and a shank-clamping device.

(5) FIG. 4 shows a cross-section of a holding device according to a second embodiment of the invention and a stud arranged in the holding device.

(6) FIG. 5 shows a cross-section of a joining head with the holding device and the stud of FIG. 4 and a shank-clamping device.

(7) FIG. 6 is a detailed view of a portion of the collet component and the stud of FIG. 1 or of FIG. 4.

(8) On the different figures, the same reference signs designate identical or similar elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) FIG. 3 and FIG. 5 show a joining head 10 comprising a holding device 12 and a shank-clamping device 14. Such joining head 10 can be used for example in a joining system such as a stud welding system. Generally, stud welding systems comprise a robot having multi-jointed arms. A welding head is secured to the end of a processing arm of the robot. The welding head is connected via an electrical supply and via a stud feed to a supply unit.

(10) The supply unit typically contains power electronics for providing a welding current, which is fed to the welding head. Furthermore, the supply unit typically contains a control device, by means of which the robot can also be activated, to be precise via a robot control. Furthermore, the supply unit contains a stud supply, from which studs are fed separately to the stud feed.

(11) The welding head contains a feed passage which is connected to the stud feed and via which a respective stud can be directed into the welding head. The stud fed to the welding head is to be welded to a workpiece, for example a metal sheet, by means of the welding system.

(12) Alternatively, however, the joining system with the joining head may also be designed to adhesively bond or braze the stud to the workpiece.

(13) As represented in the figures, the holding device 12 of the joining head 10 comprises a collet component 16. The collet component 16 has a clamping section 18 and an insertion section 20. The collet component 16 define an insertion axis X. The collet component 16 is adapted to receive a stud 22 such that the stud 22 can be inserted via the insertion section 20 to the clamping section 18, the clamping section 18 being adapted to exert a radially inwardly directed clamping force for clamping the stud 22.

(14) The stud 22 has a shank section 24, which can be provided, for example, with an external thread. Furthermore, the stud 22 has a flange section 26 which projects radially relative to the shank section and which may be of polygonal or circular design, for example, at its outer circumference. Finally, the stud has a welding section which is to be connected to the workpiece.

(15) The holding device 12 is designed to shift the stud fed via a feed passage into a ready position, in which the stud has a defined position with respect to the joining head, the position being adapted to perform the joining process described above.

(16) More particularly, the holding device 12 is adapted to secure the stud 22 against an oblique position.

(17) A securing device 28 is arranged on the insertion section (and more particularly in the insertion section). The securing device 28 comprises a securing sleeve 30. The securing sleeve 30 is hollow and comprises a bottom end.

(18) A clearance space 32 is defined between the bottom end of the securing sleeve 30 and a top end of the clamping section 18, the clearance space 32 being adapted to releasably hold a flange of a stud 22 in a securing position (also called ready position). The dimension of the clearance space 32 is such that the flange of the stud has sufficient room for maneuver in the insertion (or axial) direction.

(19) As illustrated in FIG. 2, the collet component 16 includes a slotted cylindrical front portion 34 forming the clamping section 18. A first tapered section 36 is provided between the clamping section and the insertion section. The first tapered section 36 is inclined with regard to the clamping section 18. More particularly, the first tapered section comprises a first inner surface. The clamping section 18 comprises an inner clamping surface and the first inner surface is inclined compared with the clamping inner surface at an angle of between 30 degrees and 55 degrees. In particular, the first inner surface is inclined compared with the clamping inner surface at an angle of about 40 degrees. Such angle is advantageous to provide a reliable ready position of the stud.

(20) The shape of the collet component 16, and more particularly the first tapered section facilitates the centring of the stud. Indeed, the flange 26 of the stud can contact the first tapered section and a shape cooperation can be provided for a correct positioning of the stud.

(21) In an alternative or supplemental embodiment, illustrated in FIG. 6, the first inner surface may have a curvature R which corresponds to the radius of curvature of the outer circumference of the flange. This allows the stud 22 to pivot, thus avoiding the stud to get stick.

(22) As shown in FIG. 2 and FIG. 6, a second tapered section 38 may be provided between the clamping section and the insertion section. The second tapered section comprises a second inner surface inclined compared with an inner surface of the insertion section. The second tapered section extends between the first tapered section and the insertion section. The second tapered section 38 may form an abutment surface for the securing sleeve.

(23) The studs 22 are fed in the joining head 10 with compressed air. A first air flow channel C1, oriented in a first direction is thus provided. The first direction is for example sensibly oriented parallel to the insertion axis.

(24) A second air flow channel C2, C2 oriented in a second direction, different from the first direction, is also provided. The second air flow channel C2, C2 is more particularly arranged in the securing sleeve 30, as illustrated in FIG. 1, FIG. 3, FIG. 4 and FIG. 5.

(25) As represented in FIG. 1 and FIG. 3, the securing sleeve 30 according to a first embodiment is a one-piece part. The securing sleeve 30 comprises a slot 40. The slot 40 is more particularly an annular slot. The slot 40 is adapted to receive or to form the second air flow channel C2, C2. The slot comprises an inlet to receive compressed air and an outlet to discharge the compressed air. The outlet is open toward the clearance space. The outlet is annular such that the air flow coming from the second air flow channel and directed to the flange of the stud is annular.

(26) The slot extends in cross-section along a second channel direction, the second channel direction being inclined compared to the direction of the insertion axis at an angle of between 5 degrees and 80 degrees, more particularly between 10 and 45 degrees.

(27) The securing sleeve 30 further comprises a plurality of openings adapted to receive air from the second airflow channel. The openings 42 are for example evenly distributed on the securing sleeve 30. The opening 42 extends along a longitudinal axis. The distance x between two openings is smaller than the diameter of the flange of the stud.

(28) The shank-clamping device 14 is movably arranged in the holding device, such that the shank-clamping device 14 is adapted to grip the shank of the stud 22 and to be removed to avoid obstructing the aperture to feed a further stud after the first stud has been joined to the workpiece. The plurality of openings 42 ensures that the stud is maintained in a centered position (or in the ready position) even when the shank-clamping device partially obstructs the air flow coming from the second air flow channel. More particularly FIG. 3 shows the shank-clamping device just before its movement toward the shank of the stud to grip said shank. The stud 22 is maintained in a centred position with its shank being oriented along the insertion position through the air coming from the second air flow channel. The shank-clamping device 14 can thus reliably grip the shank.

(29) The plurality of opening can be arranged, as illustrated in FIG. 1 and FIG. 3 at a non-zero distance from the bottom end of the securing sleeve or can be provided in the vicinity of said bottom end.

(30) In a second embodiment, illustrated in FIGS. 4 and 5, the securing sleeve 30 comprises a first component 301 and a second component 302. The second air flow channel C2 extends at least partly between the first component and second component.

(31) More particularly, as represented in FIG. 4 and FIG. 5, the first component has a radially projecting first flange 3011. The first component has also a first cylindrical body 3012, the first flange extending at a free end of the first cylindrical body. The first component is centred with regard to the insertion axis.

(32) The second component 302 has a radially projecting second flange 3021. The second component has also a second cylindrical body 3022, the second flange extending at a free end of the second cylindrical body. The second component is centred with regard to the insertion axis X.

(33) The second component 302 is arranged within the first component 301. The first flange 3011 is arranged facing the second flange 3021 and a space S1 is provided between the first and second flanges such that the space can form a portion of the second air flow channel. The first and second components 301, 302 can be fixedly secured to each other.

(34) The first flange and/or the second flange may form sealing elements or sealing rings.

(35) A gap S2 is provided between the first and second cylindrical body 3012, 3022, such that the gap S2 can form a portion of the second air flow channel.

(36) The bottom end of the second component is such that the air flow arriving from the second air flow channel is directed in a direction perpendicular or sensibly perpendicular to the insertion direction, as represented in FIG. 5. More particularly, the bottom end of the second component is arranged such that an annular gap S3 is formed between said bottom end of the second component and the first component. Said annular gap form a portion of the second air flow channel and allows the air coming from the second air flow channel to be oriented in a direction sensibly perpendicular to the insertion direction.

(37) The annular gap S3 or outlet in the first or second embodiment of the securing sleeve 30 could also be replaced by a plurality of nozzles evenly distributed around the circumference of the securing sleeve.

(38) When the shank-clamping device 14 moves toward the stud 22, the air flow coming from the first air flow channel C1 is interrupted. Thus, only air flow coming from the second air flow channel C2, C2 is applied to the stud. This air flow coming from the second air flow channel maintain the stud in the clearance space in a ready or centred position. The air flow from the second air flow channel C2, C2 is maintained until a front end of the shank-clamping device abuts against an abutment surface of the holding device.

(39) Although exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.