EP4613428A1

EP4613428A1 - Setting tool for a blind fastener comprising a compensation unit and method for setting a blind fastener

Info

Publication number: EP4613428A1
Application number: EP24161615.0A
Authority: EP
Inventors: Manuel Schneider
Original assignee: Newfrey LLC
Current assignee: Newfrey LLC
Priority date: 2024-03-05
Filing date: 2024-03-05
Publication date: 2025-09-10
Also published as: WO2025188821A1; WO2025188821A8

Abstract

Method for setting a blind fastener and setting tool for a blind fastener including a head and a shank partially defining an axial bore including a female thread, the blind fastener supplied to the setting tool from a blind fastener supply, and the setting tool comprising:
- a tool housing;
- a screw tool including a male thread that is rotationally and translationally movable within the tool housing along and around a tool axis between a retracted position and an extended position;
- a drive mechanism for rotationally and translationally moving the screw tool;
- a compensation unit arranged around the screw tool allowing the screw tool to move freely with regard to the tool housing, in any direction included in the transverse plane perpendicular to the tool axis,
wherein the setting tool further comprises a return device adapted to cooperate with the compensation unit for aligning the screw tool with the tool axis.

Description

The present invention is directed to a setting tool for setting a blind fastener or blind element in a workpiece or workpiece arrangement. The workpiece arrangement may comprise one or several sheets, notably metal sheets.
In motor vehicle manufacture it is usual that various components such as strips, rails, equipment etc. are fastened to thin-walled components, such as sheet metal or profiles of aluminium, for example. A common method of connecting components is to use a fastener having a screw thread.
Blind fasteners are fastening elements that are to be arranged in an opening, for example, in a through hole of a metal sheet or any other sheet or workpiece. They are commonly used to secure a plurality of workpieces together when it is difficult or impossible to access the blind side of one of the workpieces. Blind fasteners have generally incorporated a sleeve or shank that expands and bends during installation. A blind fastener can be a blind rivet nut with an internal thread and rendering possible a screw connection to metal sheets or workpieces, the wall thickness of which is not sufficient to embody a thread.
A blind fastener setting device or setting tool for blind fasteners is used to automatically set the blind fastener in the opening of the workpiece. The blind fastener (for instance a blind rivet nut) has, in a non-deformed state, a hollow cylindrical rivet shank at the one end of which a radially extending set head is embodied and on the other end of which an internal thread is formed. It is known to use a bolt having an external thread cooperating with the internal thread of the blind rivet nut to set the blind rivet nut in the hole. The internal thread of the blind rivet nut engages with the external thread of the bolt. More generally, installation of the blind rivet nut commences with the blind rivet nut or blind fastener being threaded onto a threaded mandrel or screw tool of a setting tool. The blind fastener is then inserted with the rivet shank first into the opening of a workpiece or workpiece arrangement until the rivet head contacts the workpiece. On initiation of the setting cycle the setting tool mandrel, still in engagement in the blind rivet nut, is pulled rearwards towards the flange of the blind rivet nut thereby causing deformation of the blind rivet nut body walls beyond the side of the workpiece remote from the setting tool and sandwiching the, or each sheet of material, against the face of the flange. To remove the setting device from the set blind fastener, pressure on the bolt is relieved and it is rotated in the drill-off direction. The blind fastener setting device is then available for a new setting operation.
Document EP3980220A1 from the applicant discloses for instance in more detail such setting tools.
When setting the blind fastener into the aperture of the workpiece, one of the difficulties encountered lies in positioning the blind fastener, after screwing it onto the bolt, in the aperture of the workpiece in which it must be crimped. Indeed, the precision of the location of this aperture by industrial robot driving for instance the setting tool or the setting head remains uncertain. An offset may occur between the axis of the aperture and the tool axis. A poor alignment between the tool axis and the aperture axis makes it impossible to set the blind fastener.
To overcome this drawback, DE102010039460A1 discloses a setting tool comprising means allowing the bolt and the anvil of a setting tool to move freely relative to the tool housing from a rest position to a temporary working position and for automatically and elastically returning said assembly towards the rest position.
The automatic reset of the bolt and anvil into the rest position may lead to unintentional stresses on the threaded rod or the tool, resulting either in wear or in unintended or unwanted movements which may negatively influence the setting of the blind fastener.
It is hence an object of the present invention to at least alleviate the aforementioned shortcomings. More particularly one objective of the present invention is to provide a blind fastener setting device which is of a simple design, compact, reliable and allowing a fast setting of blind fasteners in order to cut down on production time.
To this aim, according to the invention, it is provided a blind fastener setting device according to claim 1.
Such setting tool is adapted to compensate offset between the aperture and the setting tool, but also during the connection between the tool screw and the blind fastener. The return device is driven when needed and a positive force is applied to reset the screw tool in its basic position, corresponding to its alignment with the tool axis. The position of the return device can thus be commanded and adapted to the needs. There are no automatic return motions of the tool screw and therefore the device is easily adjustable to different process or needs. No special tools are required to program the setting position in the workpiece. Therefore, the position of the tool screw aligned with the tool axis can be locked by the return device and two different states of the tool screw are provided: a locked state, aligned with the tool axis and a free state adapted to compensate offset.
In an embodiment, the return device is pneumatically driven. The return movement is thus very precise. There is no additional teach tool needed for initial robot programming. The passive movement force is low. The tool components are not faced with side load (because there are no spring-loaded return components but instead a pneumatic actuator). Thus, the blind fastener can rest in the eccentric position even without external force and the eccentric position is also a stable position.
In an embodiment, the return device is an annular piston. The annular piston may be arranged around or partly around the compensation device to force said compensation device in an aligned position.
In an embodiment, the return device is movable between a first position in which it does not interfere with the compensation unit and a second position, in which it forces the compensation unit in a rest position. For instance, the first position may be a stable position.
In an embodiment, the compensation unit comprises:

a first portion adapted to cooperate directly with the return device and arranged inside the tool housing;
a second portion extending mainly outside the tool housing.

The two-parts arrangement allows for greater movement flexibility and degrees of freedom.
In an embodiment, the second portion comprises a first part which is arranged in plane articulation with the housing, and a second part which is rotatably arranged with regard to the first part. This provides a robust assembly.
In an embodiment, the first and second parts comprise aligned recesses forming an aperture in which the screw tool is arranged. In an embodiment, the first and second portions comprise aligned apertures in which the screw tool is arranged.
In an embodiment, the first portion comprises a sloped surface adapted to cooperate with the return device. The sloped surface allows a smooth transmission of movement.
In an embodiment, the drive mechanism comprises a drive unit and a drive screw cooperating with the tool screw, and wherein the drive screw is connected to the drive unit through a spherical joint. The spherical joint helps the axis compensation.
In an embodiment, the screw tool and the compensation unit are removably connected to the drive mechanism. The screw tool can thus be replaced regularly.
The present invention is also directed to a method for setting a blind fastener according to claim 11. The method allows a correct setting of blind fastener, even if the tool axis and aperture axis are not completely aligned (they can be either axially or angularly offset).
In an embodiment, the method further comprises the step of removing the tool screw from the set blind fastener and re-aligning the tool screw with the tool axis with the return device. A guaranteed concentricity is provided.
In an embodiment, the return device moves from a first position in which it does not interfere with the compensation device to a second position in which the return device forces the compensation device in an alignment position with the tool axis, the first position corresponding to a stable position.
In an embodiment, the return device is pneumatically driven from the first to the second position.
In an embodiment, the return device is elastically forced in the first position.
The invention and its advantages will be better understood from the reading of the following description, given by way of example only and with reference to the accompanying drawings, of which:

Fig. 1 shows a setting tool according to the invention;
Fig. 2 shows in greater detail in cross-section the front end of the setting tool of Fig. 1 with a screw tool, a drive mechanism, a return device and a compensation unit; Fig. 3 shows in an exploded view the compensation unit assembly group of Fig. 2;
Fig. 4 shows in an exploded view the return device assembly group of Fig. 2;
Fig. 5 shows in an exploded view the drive mechanism assembly group of Fig. 2;
Fig. 6 shows in an exploded view a pneumatical assembly group for driving the return device of Fig. 2;
Fig. 7 shows a blind fastener adapted to be used with the setting device of Fig. 1;
Fig. 8 shows the front end of a setting device according to the invention with a part presenter and a blind fastener, the screw tool facing the blind fastener;
Fig. 9 shows the screw tool of Fig. 8 engaged with the blind fastener, the blind fastener being still in its presenter;
Fig. 10 shows the screw tool with the blind fastener disengaged from the presenter, the screw tool being aligned with a tool axis, the return device forcing the compensation device in a position such that the screw tool is maintained aligned with the tool axis;
Fig. 11 shows the front end of the setting tool and a workpiece arrangement having an aperture, an aperture axis being offset with regard to the tool axis, the screw tool being offset by the compensation unit in order to correctly insert the blind fastener into the aperture;
Fig. 12 shows the blind fastener being set into the aperture by the setting tool;
Fig. 13A and Fig. 13B show in perspective the compensation unit, the drive mechanism, the screw tool and the return device of a setting tool according to the invention, the return device and screw tool being disassembled from the drive mechanism (in Fig. 13A) and then assembled again (in Fig. 13B)
Fig. 14A and Fig. 14B show in cross section the details of Fig. 13A and Fig. 13B, a bayonet coupling being used for the assembly and disassembly of the return device and screw tool from the drive mechanism.

The embodiments of the disclosure will be best understood by reference to the drawings, wherein the same reference signs designate identical or similar elements. It will be readily understood that the components of the disclosed embodiments, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the systems and methods of the disclosure is not intended to limit the scope of the disclosure, as claimed, but is merely representative of possible embodiments of the disclosure.
Fig. 1 shows a setting tool 10 for blind fasteners or blind elements. As illustrated, the setting tool 10 comprises a housing 12 with different housing portions and a tool nose or front end 14. The housing 12 is adapted to be attached to an arm of a robot (not represented) through an interface.
The setting tool 10 comprises a tool shaft connected to a tool screw 18, the tool screw 18 being adapted to engage with the internal thread of a blind fastener 20. The tool shaft and the tool screw 18 are rotationally and translationally movable through a first and/or second transmission device which respectively works with a first and/or second electric motor. The tool shaft and the tool screw 18 are rotationally and translationally movable along and around a tool axis X which corresponds to a longitudinal axis of the setting tool 10. The tool shaft and the tool screw 18 are rotationally and translationally movable with regard to the housing 12. The setting tool may further comprise a solid roller screw connected to the tool shaft, and more particularly fixedly assembled to the tool shaft such that a rotation or a translation of the solid roller screw may be transferred to the tool shaft. The setting tool and the transmission arranged inside the setting tool is for instance disclosed in WO2020245310A1 of the applicant which is hereby incorporated by reference. In another embodiment, other arrangements may be implemented to drive the tool shaft and the tool screw in translation and rotation. As better seen in Fig. 2, the setting tool comprises the front end 14 with the tool screw 18, a drive mechanism 22, a compensation unit 24 and a return device 26. The tool screw 18, drive mechanism 22, compensation unit 24 and return device 26 cooperate in order to give the tool screw radial and angular degrees of freedom. More particularly a radial degree of freedom in the range of up to 3 millimeters and in particular 1.5 millimeters are possible. Similarly, an angular degree of freedom of up to 5 degrees and more particularly up to 3 degrees is possible.
The drive mechanism 22 is adapted to drive in translation and in rotation the tool screw 18. The compensation unit 24 is adapted to allow the tool screw 18 to be moved in a position misaligned from the tool axis to compensate an eventual offset between a tool axis and an aperture axis during the arrangement of the blind fastener within the aperture and its setting. The return device 26 is adapted to force the compensation unit 24 back in a rest position such that the tool screw 18 is again aligned with the tool axis X.
The tool screw 18 comprises for example a head 182 and a shaft 184. The shaft 184 comprises a male threaded portion 186. The head 182 extends radially from an end of the shaft 184. The male threaded portion 186 is arranged opposite the head 182. The head 182 is arranged inside the setting tool housing 12, wherein the threaded portion of the shaft is adapted to be driven outside of the housing 12 to engage with the blind fastener 20.
The different assembly groups of the compensation unit 24, return device 26 and drive mechanism 22 are depicted in more detail in Fig. 3, Fig. 4 and Fig. 5.
Fig. 3 shows in detail the compensation unit 24 assembly group. Said compensation unit 24 comprises a first portion 242 adapted to cooperate directly with the return device 26. The first portion 242 may for instance comprise a first part 2422 and a second part 2424. The first part 2422 cooperates with the return device 26, wherein the second part 2424 is arranged in a planar joint with the first part 2422.
The first and second parts 2422, 2424 comprise through holes which are aligned to form an aperture 28 receiving the screw tool.
The first part 2422 may comprise an outer surface facing the drive mechanism and the return device. Said outer surface comprises a first segment S1 adapted to contact the head 182 (and more precisely the underside of the head) of the tool screw. The first segment S1 extends for instance substantially orthogonal to a longitudinal axis X18 of the tool screw 18. The outer surface may also comprise a second segment S2, extending substantially parallel to the first segment S1, a shoulder extending between the first and second segments S1, S2. The outer surface may comprise a third segment S3. The third segment S3 may be sloped or curved. The third segment S3 extends from the second segment S2 at an angle between 0 and 90 degrees. The third segment S3 is adapted to cooperate with the return device 26. More particularly, the return device can contact and apply an effort of the third surface S3. The sloped orientation of the third surface S3 is advantageous such that the effort applied on the compensation unit 24 by the return device 26 is smooth.
The first part 2422 may also comprise an inner surface. The inner surface may be sloped or curved and cooperate with the second part 2424. A first collar 2426 may extend from the inner surface.
The second part 2424 may have an outer surface which cooperates with the inner surface of the first part 2422. Both inner surface of the first part and outer surface of the second part may be curved surfaces having complementary shapes such that the second part 2424 may rotatably slide on the second part (forming a kind of spherical joint). The outer surface of the second part 2424 defines a recess 2428 in which the first collar 2426 may extends. The second part 2424 may have a planar inner surface, which can be substantially orthogonal to the axis defined by the aperture 28. A second collar 2430 may extend from the planar inner surface.
The first and second part 2422, 2424 are arranged for instance substantially in a sleeve 30. The sleeve 30 may be part of the housing 12. The sleeve 30 comprises a recess 32 in which the first and second parts 2422, 2424 are arranged. The sleeve 30 further comprises a base wall 302 defining a sleeve aperture 304. The base wall 302 has a first surface facing the recess 32 and a second surface opposite the first surface. The planar inner surface of the second part 2424 contacts the first surface of the base wall 302, wherein the second collar 2430 extends through the sleeve aperture 304.
A washer 34 may be arranged contacting the second surface of the base wall 302 and around the second collar 2430.
The first portion 242 is substantially inside the housing 12 of the setting tool 10.
The first portion 242 is followed by a second portion 244 which extends substantially outside of the housing 12. The second portion 244 comprises for instance also a third part 2442 adapted to be in surface contact with the second surface of the base wall 302. The third part 2442 may slide with regard to the second surface of the base wall 302. Rollers may be provided to limit the friction during the motion of the second portion 244 with regard to the base wall 302. The third part 2442 comprises for instance a planar surface contacting the second surface of the base wall 302 and adapted to slide with regard to the base wall 302. Opposite the planar surface a curved concave surface S4 may be provided. The curved concave surface S4 may be in surface contact with a cooperating inner surface of a fourth part 2444 of the second portion. For instance, third and fourth parts 2442, 2444 may move relative to each other through the cooperating surfaces forming in substance a spherical joint.
The second portion 244 defines an aperture 36 which is aligned with the aperture 28 defined by the first portion and adapted to receive the tool screw 18. More particularly, a tubular case 38 may be received in the aperture, and the tool screw 18 extends in the tubular case 38. A spring may extend between the tubular case 38 and the aperture 36 of the second portion 244 or part of said aperture 36. The spring is adapted to hold the fourth part 2444 of the second portion 244 in contact with the third part 2442.
The fourth part 2444 of the second portion 244 may be adapted to cooperate with a cap 40. The cap 40 can for instance be press fitted at the end of the fourth part 2444 and have a through hole aligned with the apertures 28, 36 to arrange the tool screw 18.
The apertures 28, 36 defined by the first and second portions 242, 244 are all adapted to receive the tool screw, and more particularly to receive directly or indirectly the shaft of the tool screw, said tool screw being movable in rotation and in translation along its longitudinal axis.
From a kinematic point of view the compensation unit 24 has the following pairs. The first and second parts 2422, 2424 slide with regard to each other in a substantial spherical joint. The second part 2424 is adapted to slide in a substantial planar joint with the base wall 302 of the sleeve 30 (more particularly with the surface facing the recess 32). The third part 2442 also slides in a substantial planar joint with the base wall 302 of the sleeve 30 (on the surface opposite the recess 32). The third and fourth parts 2442, 2444 slide with regard to each other in a substantial spherical joint.
As mentioned above the compensation unit 24 cooperates with the return device 26.
Fig. 4 shows in more details the various parts forming the assembly group of the return device 26. As visible for instance from Fig. 2 and Fig. 4, the return device 26 comprises a piston 42, and more particularly an annular piston 42. The piston 42 is adapted to move in translation inside the recess 32 of the sleeve 30 between a first position and a second position. In the first position, the return device 26, and more particularly the annular piston 42 is at a non-zero distance from the compensation unit 24, and more particularly from the first portion 242 and even more particularly from the first part 2422 of the first portion. In the second position, the return device 26, and more particularly the annular piston 42 contacts the compensation unit 24 and is adapted to lock the compensation device 24 in an aligned position (as better disclosed later). The piston 42 is movable in a piston casing 44. The casing 44 is arranged inside the sleeve 30. A spring 46 may extend between a portion of the casing 44 and the piston 42. The piston 42, as mentioned above is annular and comprises an annular base 48. The annular base 48 is adapted to contact the compensation unit 24. More particularly, the annular base 48 is adapted to contact the first portion 242 (and for instance the third segment S3). The sloped or curved surface of the third segment S3 can cooperate with the annular base 48 such that the annular base 48, when the piston 42 translates from its first position to its second position, applies an effort of the third segment S3 and eventually moves the first part 2422, which then applies an effort on the second part 2424 of the first portion 242. The force is then forwarded to the second portion 244, such that the parts of the first and second portion 242, 244 are moved to reach a position in which the aperture axis (corresponding to the general axis defined by the apertures 28, 36) is aligned with the tool axis. The annular base 48 comprises a flange 50. The spring 46 may seat between the flange of the annular base, the outer surface of the lateral walls of the piston 42 and the casing 44. The spring 46 allows an elastic return of the piston in a rest position which corresponds to the first position (at a non-zero distance from the compensation device). Thus, when no particular external force applies on the piston 42, the return device 26 is per default in the first position. The casing 44 may cooperate (for instance it can be screwed) with the sleeve 30 of the compensation unit. The casing 44 is for instance a two-parts casing with a first casing part 442 extending between the compensation unit 24 and a second casing part 444. The second casing part 444 being connected to the sleeve 30. Rollers can be provided between the piston 42 and the casing 44. The piston 42 is annular such that the tool screw 18 may extend in the cylindrical recess of the piston and translate or rotate independently of the position of the piston. Notably the piston 42 defines a cylindrical recess 54 having a diameter which is greater than the diameter of the head of the tool screw 18.
The piston 42 is pneumatically driven. Fig. 6 for instance shows a pneumatical assembly group 56 for driving the return device 26. The return device is driven by a pneumatical source. More particularly a controller commands a pneumatical source such that the return device (and more particularly the annular piston) moves from the first to the second position. The pneumatical assembly group comprises an inlet sleeve 58 with a fluid (for instance pressured air) inlet nozzle 60. The inlet sleeve 58 cooperates with an annular body 62 arranged around the sleeve 30. The annular body 62 comprises a first fluid channel 64 cooperating with a second fluid channel 66 provided in the sleeve 30. The first and second fluid channels cooperate together such that a pressured air flow coming from a pressured air source enters the inlet nozzle 60 and is then guided in the first and second fluid channels 64, 66 up to the inside of the piston casing 44. Thus, the pneumatical source command the inlet of pressurized air, which applies an effort on the piston to drive the piston 42 from the first position to the second position.
As mentioned above, the tool screw 18 is adapted to freely move within the apertures 28, 36 and the cylindrical recess 54. More particularly, the tool screw 18, for setting the blind fastener 20, translates and rotates along and around its longitudinal axis X18 which, for a correct setting of the blind fastener 20, needs to be aligned with the aperture in which the blind fastener needs to be set.
Fig. 5 shows the drive mechanism 22 assembly group. The drive mechanism 22 is adapted to drive the tool screw 18. The drive mechanism 22 comprises a driving pin 68 cooperating with the tool screw 18. The driving pin 68 extends longitudinally between a first end 681 and a second end 682. The first end 681 cooperates with the tool screw 18. For instance, the first end 681 is arranged in a blind hole of the tool screw head 182. There is a shape cooperation between the bling hole and the first end 681 such that rotation and translation motions can be forwarded from the driving pin 68 to the tool screw 18. The second end 682 of the driving pin 68 cooperates with a driving body 70. The driving body 70 is for instance removably fixed to the sleeve 30. The driving body 70 is adapted to drive in translation the tool screw but also the compensation unit 24.
The driving body 70 is for example screwed to the sleeve 30.
The driving body 70 may also be snap fitted to the sleeve 30.
Preferably the driving body 70 is removably fixed to the sleeve 30, so that the assembly groups formed by the compensation unit 24, return device and the tool screw 18 may be disassembled from the housing 12 and the drive mechanism, for instance for maintenance or to change a wear tool screw 18.
As notably depicted in Fig. 13A, Fig. 13B, Fig. 14A and Fig. 14B, a bayonet coupling may be implemented. The bayonet coupling enables a fast and safe change of the tool screw 18. The bayonet coupling 100 comprises for instance female hooks 102 adapted to cooperate with male hooks 104. The female hooks are for instance arranged within the sleeve 30. The male hooks are for instance arranged on the driving body 70. In other embodiments, male hooks are arranged on the sleeve and female hooks on the driving body. An outer sleeve 106 may be provided around the driving body 70. The outer sleeve 106 is for instance spring-loaded.
In order to assemble the first assembly group formed by the compensation unit 24, return device and the tool screw 18 from the second assembly group formed by the drive mechanism with the driving body and the housing 12, first and second assembly groups are first aligned and the first assembly group is pushed towards the second assembly group (see arrow A1 in Fig. 13B) so that the driving pin 68 enters the sleeve 30 until it comes in abutment. The first assembly group is then rotated (see arrow A2 in Fig. 13B) with regard to the second assembly group in order to lock first and second assembly group together.
To disassemble the first and second assembly groups, one of the first and second assembly group is rotated with regard to the other of the first and second assembly group for disengaging the female and male hooks. Then, a relative translation is applied to separate the first and second assembly groups.
The driving pin 68 comprises a shaft portion 683 and an enlarged portion 684 between the first and the second end 681, 682. The first end 681 extends from the shaft portion 683 and has for instance a smaller diameter than the shaft portion. The driving body 70 is controlled by one or several actuators for the translation and the rotation in order to realize the setting of the blind fastener or blind element 20.
The second end 682 of the driving pin 68 is arranged in a blind recess of the driving body 70. For instance, the driving body 70 comprises a first recess 702 with a first diameter and, in the central part of the first recess 702, a second recess 704, with a second diameter, smaller than the first diameter. The enlarged portion 684 extends from the shaft portion 683. The enlarged portion 683 extends substantially in the first recess 702. The enlarged portion 683 comprises a surface adapted to rest against the periphery of the second recess 702. The second end 682 has a diameter smaller than the enlarged portion 683 and is arranged in the second recess 704. For instance, the second end 682 has lateral curved surfaces. The second end 682 may be provided with an aperture for its connection to the driving body 70 through a connecting element 72. The second end 682 is movable inside the second recess 704 in rotation (more particularly there is clearance between the parts (second end 682 and second recess 704) to allow limited rotational movement of the second end 682 within the second recess 704. More particularly, the second end 682 has in the second recess a certain degree of freedom in rotation such that the driving pin axis of the driving pin may form an angle with the tool axis X (corresponding to the general main longitudinal axis of the driving body 70).
Fig. 2, as mentioned above show in more details the arrangement of the different assembly groups to form the front end of the setting tool 10.
The setting tool is adapted to work with blind fasteners for their setting in an aperture of a workpiece, and notably with blind fasteners as depicted in Fig. 7. For instance, the blind fastener 20 is a blind rivet nut 20. The blind rivet nut comprises a head forming a flange 201 and a shank 202. The shank 202 comprises a head end 203 and a foot end 204. The head end 203 is arranged proximal to and in the continuity of the head, wherein the foot end 204 forms a free end. The foot end 204 comprises a foot end angle A with the longitudinal axis X20 of the blind rivet nut. The foot end angle A is a non-zero angle (A >0°). The foot end angle A is realized by a tapered chamfer. The foot angle A is between 21° and 25° with the longitudinal axis X20. For instance, the foot end angle A is of about 23°.Further the shank 202 has an outer surface in the form of a regular polygonal prism or of a cylinder. The regular polygonal form of the shank increases the resistance against a rotation of the assembled blind rivet nut in an aperture of a sheet material. The shank 202 is provided with a recess and an internal thread. The internal thread extends only on a portion of the length of the shank 202.
The setting tool 10 as described above may be used as follows to set a blind fastener 20, notably the blind fastener 20 as described above.
In a first step, as depicted in Fig. 8, a part presenter 74 with a blind fastener and the setting tool 10 are moved relative to each other such that the tool screw 18 of the setting tool 10 faces the recess of the blind fastener. The return device is in the rest position, which is the first position. The position of the tool screw 18 with regard to the blind fastener 20 is such that the longitudinal axis X18 of the tool screw 18 is aligned with the longitudinal axis X20 of the blind fastener 20. Eventually an offset may occur between the two axis X18 and X20. If an offset appears between the two axes, the compensation unit 24 may compensate the offset when the tool screw 18 is inserted into the blind fastener 20. Indeed, if there is an offset between the two axes, when the tool screw is moved down in the direction of the blind fastener 20, the tool screw will not directly enter the recess of the blind fastener but will contact the edge of the recess. The contact will create an effort of the tool screw 18, and, through the different kinematic pairs of the compensation unit 24 explained above, the compensation unit 24 will allow the tool screw to move in order to re-align of the longitudinal axis X18 of the tool screw 18 with the longitudinal axis X20 of the blind fastener. Once the axis X20 and X18 are aligned, the tool screw 18 can engage the internal thread of the blind fastener, as shown in Fig. 9.
The blind fastener 20 is then removed from the part presenter 74 by the setting tool 10 and the setting tool 10 with the blind fastener 20 engaged to the tool screw 18 may be moved by a robot for instance toward a workpiece arrangement 76 where the blind fastener has to be set, as shown in Fig. 10. The workpiece arrangement 76 comprises one or more sheet and an aperture 78 in which the blind fastener can be set. In fig. 10, the return device is in the second position, which corresponds to a locked position of the compensation unit 24. A pressure has been applied to the piston 42 so that it moved from the first to the second position. The piston 42 applies an effort on the first position of the compensation unit 24, and forces thus the tool screw 18 to be aligned with the tool axis X. Thus, a sort of recess of the tool screw position is realized after the pick up of the blind fastener and before the setting of said blind fastener 20.
The setting tool 10 is then arranged facing the workpiece arrangement with the aperture 78. The return device is put backed in the first position. The aperture 78 is centred around an aperture axis X78. The aperture 28 comprises dimensions which are similar to, slightly greater than the outer dimension of the blind fastener 20, such that the shank 202 can be interested into the aperture, whereas the head 201 rests against the surface directly at the periphery of the aperture.
To facilitate the insertion of the blind rivet nut 10 into the aperture 28, the foot end 18 of the blind fastener may, as disclosed above, be provided with a chamfer. The chamfer thus facilitates the insertion of the blind fastener within the aperture 78 . When the tool screw engaged with the blind fastener 20 is moved down the aperture 78, if the aperture axis X78 and the longitudinal axis X18 of the tool screw 18 are not completely aligned, an edge of the blind fastener, notably the chamfer contacts the periphery of the aperture. The tool screw not being locked in a position such that its longitudinal axis is aligned with a tool axis X, the offset between the aperture axis X78 and the tool axis X may be compensated by the tool screw and the compensation unit such that the tool screw, during the insertion of the blind fastener, rotates or translates in reaction to the contact between the blind fastener and the edge of the aperture, such that the shank 202 is inserted into the aperture until the head reached the workpiece. As visible in Fig. 11, the driving pin 68 deviates with regard to the tool axis X, such that the general axis of the pin X68 forms an angle with the tool axis (the second end 682 moves in the second recess 704, the first end moves in the head of the tool screw and the first and second portions of the compensation unit moves with regard to the housing).
Once the head of the blind fastener has reached the workpiece arrangement, the blind fastener may be set. A portion of the tool screw 18 moves backward within the housing 12, and thus, a portion of the blind fastener 20 collapses (the head of the blind fastener resting against the cap which is an anvil and which does not move during the crimping step), as visible in Fig. 12. During the crimping step, the axis of the tool screw X18 remains offset with the tool axis X. The compensation unit 24 allowing the "pulling" (translation backward of the tool screw) in an offset state. The tool axis X and the axis of the aperture X78 may thus be offset up to 3 millimeters and/ 5 degrees.
Once the crimping step is done, the tool screw 18 disengages with the collapsed blind fastener 20. The return device 26 can then be moved from the first to the second position in order to reset the position of the axis such that the tool screw 18 is realigned with the tool axis X.
The tool screw 18 may be damaged after few setting processes. As mentioned above and depicted in Fig. 13, the assembly comprising the screw tool, the return device and the compensation unit 24 may be disassembled from the rest of the setting tool 10 such as to replace or repair damaged parts.

setting tool 10
housing 12
front end 14
tool screw 18
longitudinal axis X18 of the tool screw 18
head 182
shaft 184
male threaded portion 186
blind fastener 20
flange 201
a shank 202
head end 203
foot end 204
foot end angle A
longitudinal axis X20
drive mechanism 22
compensation unit 24
first portion 242
first part 2422
second part 2424
first segment S1
second segment S2
a third segment S3
first collar 2426
recess 2428
second collar 2430
second portion 244
third part 2442
curved concave surface S4
fourth part 2444
return device 26
tool axis X
aperture 28
a sleeve 30
base wall 302
sleeve aperture 304
recess 32
washer 34
aperture 36
tubular case 38
cap 40
piston 42
piston casing 44
first casing part 442
second casing part 444
spring 46
annular base 48
flange 50
cylindrical recess 54
pneumatical assembly group 56
inlet sleeve 58
inlet nozzle 60
annular body 62
first fluid channel 64
second fluid channel 66
driving pin 68
first end 681
second end 682
shaft portion 683
enlarged portion 684
driving body 70
first recess 702
second recess 704
connecting element 72
part presenter 74
workpiece arrangement 76
aperture 78
bayonet coupling 100
female hooks 102
male hooks 104
an outer sleeve 106

Claims

Setting tool for a blind fastener including a head and a shank partially defining an axial bore including a female thread, the blind fastener supplied to the setting tool from a blind fastener supply, and the setting tool comprising:
- a tool housing;

- a screw tool including a male thread that is rotationally and translationally movable within the tool housing along and around a tool axis between a retracted position and an extended position;

- a drive mechanism for rotationally and translationally moving the screw tool;

- a compensation unit arranged around the screw tool allowing the screw tool to move freely with regard to the tool housing, in any direction included in the transverse plane perpendicular to the tool axis,
Characterized in that the setting tool further comprises a return device adapted to cooperate with the compensation unit for aligning the screw tool with the tool axis.
Setting tool according to claim 1, wherein the return device is pneumatically driven.
Setting tool according to claim 1 or 2, wherein the return device is an annular piston, and wherein the return device is movable between a first position in which it does not interfere with the compensation unit and a second position, in which it forces the compensation unit in a rest position.
Setting tool according to any of claims 1 to 3, wherein the compensation unit comprises:
- a first portion adapted to cooperate directly with the return device and arranged inside the tool housing;

- a second portion extending mainly outside the tool housing.
Setting tool according to claim 4, wherein the second portion comprises a first part which is arranged in plane articulation with the housing, and a second part which is rotatably arranged with regard to the first part.
Setting tool according to claim 5, wherein the first and second parts comprise aligned recesses forming an aperture in which the screw tool is arranged.
Setting tool according to any of claims 4 to 6, wherein the first portion comprises a sloped surface adapted to cooperate with the return device.
Setting tool according to any of claims 1 to 7, wherein the first and second portions comprise aligned apertures in which the screw tool is arranged.
Setting tool according to any of claims 1 to 8, wherein the drive mechanism comprises a drive unit and a drive screw cooperating with the tool screw, and wherein the drive screw is connected to the drive unit through a spherical joint.
Setting tool according to any of claims 1 to 9, wherein the screw tool and the compensation unit are removably connected to the drive mechanism.
Method for setting a blind fastener, the method comprising the steps of:
- providing a setting tool according to any of claims 1 to 10;

- providing a blind fastener including a head and a shank partially defining an axial bore including a female thread;

- providing a workpiece with an aperture, wherein the aperture is centered around an aperture axis;

- connecting the tool screw into the axial bore of the blind fastener;

- moving the setting tool such that the blind fastener faces the aperture with the tool axis (X) and the aperture axis (Xa) being offset up to 1,5mm and/or up to 3 degrees;

- inserting the blind fastener into the aperture, the compensation unit compensating the offset between the aperture axis and the tool axis;

- setting the blind fastener into the aperture.
Method according to claim 11, further comprising the step of removing the tool screw from the set blind fastener and re-aligning the tool screw with the tool axis with the return device.
Method according to claim 12, wherein the return device moves from a first position in which it does not interfere with the compensation device to a second position in which the return device forces the compensation device in an alignment position with the tool axis, the first position corresponding to a stable position.
Method according to claim 13, wherein the return device is pneumatically driven from the first to the second position.
Method according to claim 13 or claim 14, wherein the return device is elastically forced in the first position.