GB2572071A

GB2572071A - Self-pierce riveting device

Info

Publication number: GB2572071A
Application number: GB1903215.0A
Authority: GB
Inventors: Philipskoetter Andre; Woelke Florian
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-03-13
Filing date: 2019-03-11
Publication date: 2019-09-18
Anticipated expiration: 2039-03-11
Also published as: GB201903215D0; DE102018203720A1; GB2572071B

Abstract

A self-piercing riveting device 10' comprises a vibration system 39 which is attached to a drive 50 and can be moved relative to a frame 60 by means of the drive 50 and a punch 15 which is coupled or can be coupled with the vibration system 39 in such a way that it can be made to vibrate as the rivet 20 is driven into at least two components 11, 12. A guide 70 is provided which is mounted on the frame 60 and on which the vibration system 39 is indirectly or directly retained and can be guided in the joining direction R. The frame may be C-shaped and the guide 70 may be disposed on leg 61 or disposed between legs 61, 62 of the frame (as in figure 4). The vibration system may comprise booster 31 via which a vibration generator 32 is connected to a sonotrode comprising the punch 15. Measuring system 71 may determine the movement or position of the vibration system relative to the support.

Description

(57) A self-piercing riveting device 10' comprises a vibration system 39 which is attached to a drive 50 and can be moved relative to a frame 60 by means of the drive 50 and a punch 15 which is coupled or can be coupled with the vibration system 39 in such a way that it can be made to vibrate as the rivet 20 is driven into at least two components 11, 12. A guide 70 is provided which is mounted on the frame 60 and on which the vibration system 39 is indirectly or directly retained and can be guided in the joining direction R. The frame may be Cshaped and the guide 70 may be disposed on leg 61 or disposed between legs 61, 62 of the frame (as in figure 4). The vibration system may comprise booster 31 via which a vibration generator 32 is connected to a sonotrode comprising the punch 15. Measuring system 71 may determine the movement or position of the vibration system relative to the support.

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Fig. 2

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Fig. 3

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Fig. 4

Self-pierce riveting device

Description

This invention relates to a self-pierce riveting device for a vibration-assisted process for joining at least two components by means of a rivet.

Prior art

Methods and devices for self-pierce riveting are used to join at least two components that are flat in particular in a joining area. A self-pierce riveting process is distinctive because it is not necessary to pre-punch a hole in the components to be joined to one another. Instead, a rivet is driven into the at least two components by means of a punch or a punching tool, and a correspondingly shaped supporting tool, e.g. in the form of a die co-operating with the punching tool, ensures that the rivet deforms in a specific manner inside the components to be joined to one another in order to produce a non-positive and positive join between the components and at the same time prevent penetration of the component remote from the rivet.

Also known from EP 2 318 161 Bl or DE 10 2014 203 357 Al, for example, are so-called ultrasonic self-pierce riveting methods and devices, for which a vibration generator, such as an ultrasound generator for example, is used in order to make one or more components vibrate whilst the components are being joined. Due to this vibration, the force which has to be applied in order to drive the rivet in is reduced, for example.

Disclosure of the invention

The invention proposes features defined in constitute the subject a self-pierce riveting device having the claim 1. Advantageous embodiments matter of the dependent claims and the following description.

A self-pierce riveting device proposed by the invention is used to join at least two components by means of a rivet and has a punch and a supporting tool between which the at least two components and the rivet can be positioned. The self-pierce riveting device further comprises a drive which is disposed on a frame of the self-pierce riveting device and by means of which a force direction, i.e.

can be applied to the punch in the direction of in the joining the supporting tool. In addition, the self-pierce riveting device has a vibration system which is attached to the drive and can be moved relative to the frame by means of the drive. Accordingly, the vibration system comprises the punch, which in particular may in turn be provided as part of a sonotrode used in the vibration system.

This sonotrode may therefore also constitute as a punch. The vibration system may also the punch or serve have a vibration convertor in particular, for example an electromechanical convertor such as a piezoelectric convertor with which the vibration sonotrode.

amplitude may also be provided in addition, via amp1i f i e r) vibration convertor is connected to the sonotrode.

which the

Furthermore, the vibration system is coupled or can be coupled with a vibration generator in such a way that it can be made to vibrate as the rivet is driven into the at least two components. The vibration generator is preferably a sound generator, in particular an ultrasound generator. It may also be expedient to provide a clamp by means of which the at least two components can be pressed against the supporting tool and/or can be secured on the supporting tool. The supporting tool may then also be disposed on the frame.

A guide device may also be provided, in particular in the form of a guide rail, for example also in the form of a profiled guide or a linear guide, which is mounted on or secured to the frame and on which the vibration system is indirectly or directly retained and can be guided in the joining direction (and also in the opposite direction). The vibration system can then be secured to the drive, in particular by means of a retaining device and (thus indirectly) retained and guided on the guide device. Such a retaining system can be used to provide a vibration-optimised suspension of the vibration system for example, as will be explained in more detail below. If not using such a retaining system however, the vibration system may also be directly retained and guided on the guide device, for example with the vibration convertor and/or the booster .

In self-pierce riveting processes assisted by vibration and/or ultrasound, the high-frequency longitudinal vibration of the vibration system and/or the joining tool (in particular the sonotrode) - a vibration direction of the vibration system is then oriented in the joining direction in particular - can lead to a lateral migration or bending or shifting of the vibration system and/or joining tool. This is caused by high lateral transverse forces which can occur due to a hammering or percussive movement of the punch on the rivet or due to a vibrating motion of the punch in permanent contact with the rivet, in each case in combination with a slight or the slightest unevenness (such as for example component radii, uneven sheets, inadequately adjusted or set tool alignment, bending of the frame, unsymmetrical design of the support and such like) and can have a negative effect on the service life of the tool and quality of the joining point.

The coaxial alignment of the tools used that is needed before, during and after the joining process to obtain a join of high quality can therefore not be obtained or guaranteed. In the case of conventional self-pierce riveting devices known to date (that are not assisted by vibration or ultrasound systems), such transverse forces are unknown on this scale because the joining tool is not subjected to high-frequency longitudinal vibrations .

However, such high transverse forces, which may be up to 5 kN for example, can be counteracted by the proposed guide device or guide rail. Furthermore, this guide device is able to compensate for the differing weight distribution on the two arms and/or legs of the frame if it is provided in the form of a so-called C-frame or C-support due to the relatively heavy drive and likewise relatively heavy components of the vibration system and to prevent resultant shifting of the tool, and reduce to a minimum any lifting of the integrated components, for example due to rapid acceleration or deceleration of a robot by means of which the self-pierce riveting device is moved in space when the frame is being moved into different spatial positions and positioned on the component.

In this context, the frame is preferably provided in the form of a C-frame, in which case the guide device is disposed on a leg of the frame on which the drive as well as the components of the vibration system in particular are also disposed. The guide device can therefore be disposed on and secured to the frame very close to the drive and the components of the vibration system (i.e. the components which generate the joining force).

Alternatively, it is preferable when the frame is provided in the form of a C-frame for the guide device to be disposed between two legs of the frame on which the drive and the supporting tool are disposed (the latter respectively on different legs). The guide device is therefore disposed on the so-called support back in particular. The guide device can then be secured in a flat arrangement or by certain points only for example .

In both variants, the guide device or guide rail serves simultaneously as a guide for the vibration system and a means of laterally stabilising the vibration system, which overall leads to a particularly accurate self-pierce riveting operation whilst also increasing the service life of the self-pierce riveting device.

The self-pierce riveting device advantageously also has a position measuring system by means of which a movement and/or a position of the vibration system relative to the guide device can be determined. Detection of the movement or position of the punch - for example by the vibration system - is important to the self-pierce riveting operation to enable it to be carried out particularly accurately and the proposed guide device enables a particularly precise measurement of the movement or position to be obtained because as a result of the guiding action along the guide device no undesired inaccuracies occur. An appropriate position sensor or similar may then be used for this purpose for example, which transmits a corresponding signal to a control unit of the self-pierce riveting device.

There, the signal can then be processed to obtain the movement or position and used to control or regulate the self-pierce riveting device for example.

Other advantages and embodiments of the invention will become apparent from the description and accompanying drawings.

It goes without saying that the features outlined above and those still to be described below may be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the present invention.

The invention is schematically illustrated in the drawings on the basis of examples of embodiments and will be explained in detail below with reference to the drawings.

Description of the drawings

Figure 1 is a simplified and schematic illustration of a production device having a self-pierce riveting device as proposed by the invention.

Figure 2 is a schematic illustration of a self-pierce riveting device that is not based on the invention.

Figure 3 is a schematic illustration of a self-pierce riveting device proposed by the invention based on a preferred embodiment.

Figure 4 is a schematic illustration of a self-pierce riveting device proposed by the invention based on another preferred embodiment.

Detailed description of the drawings

Figure 1 provides a simplified and schematic illustration of a production device 100. The production device 100 may be an industrial robot in a production plant for example, for the construction of car bodies for example.

Accordingly, the production device 100 has a support structure 3 disposed on a floor and two mutually connected and movable arms 4 and 5 mounted thereon. Disposed on the end of arm 5 is a self-pierce riveting device 10' proposed by the invention based on a preferred embodiment, which is only schematically illustrated here but will be described in more detail below.

Also illustrated is a computer unit 80 which is a control unit of the self-pierce riveting device 10' for example. The computer unit 80 may furthermore also be provided as a control unit for the entire production device, i.e. for also controlling the movable arms in particular, in addition to the self-pierce riveting device. Display means 90 are also provided, for example a display on which current operating parameters of the self-pierce riveting device can be displayed for example. The element 90 may also be a combined display/input means, e.g. a touchscreen.

Figure 2 provides a schematic illustration of a self-pierce riveting device 10 that is not based on the invention which will be used to explain a problem that is solved by this invention. The self-pierce riveting device 10 has a frame 60 which is preferably provided in the form of a C-frame or Csupport on which the individual components of a self-pierce riveting device are disposed as a rule to enable them to assume the desired position relative to one another. Via the frame 60, the self-pierce riveting device 10 can be attached to an arm for example, as illustrated in Figure 1.

The self-pierce riveting device 10 has a punch (and/or a sonotrode) 15, for example with a round cross-section. The punch 15 is radially surrounded by a (tubular) clamp 16 and disposed so as to be movable relative to it in the longitudinal direction. In this context, the clamp is preferably secured by means of a spring at a so-called zero amplitude crossing of the punch, i.e. a position of the punch at which vibration amplitudes are zero or at least as low as possible. In particular, the punch 15 is coupled with a drive 50 which is used to apply in the joining direction R a force F needed to drive the rivet 20 into the two components 11, 12. The drive 50 may be controlled by means of the computer unit 80 for example. Accordingly, the force F may be predefined as a setpoint value and detected as an actual value for example.

The clamp 16 is also set up so that it presses against the surface of the component 11 facing the punch 15 with a clamping force. For example, a separate drive may be provided for this purpose. However, the clamp may also (as illustrated here) be coupled with the drive of the punch or with the punch itself, for example by means of a spring.

Disposed on the side of the two components 11, 12 lying opposite the punch 15 and clamp 16 is a supporting tool in the form of a die 18. The punch 15 and the die 18 are disposed in the vertical direction, as is also the clamp 16, and are movable relative to one another but the die 18 itself is not movable as a rule. The clamp 16 and the die 18 are used to clamp and press together the two components 11, 12 between the clamp 16 and the die 18 during processing by means of the punch 15.

The rivet 20, a semi-tubular self-piercing rivet in this instance by way of example, is preferably made from a material that is harder than the materials of the two components 11, 12, at least in the region of a rivet shaft. The flat top end of the rivet facing away from the component 11 is disposed operatively connected to the punch 15 which lies flat against the top end of the rivet 20.

The punch 15 is operatively connected to a (mechanical) vibration convertor 30, for example a piezoconvertor. The vibration convertor 30 is in turn connected to a (electric) vibration generator, for example an ultrasound generator. This being the case, oscillations or vibrations can be generated and induced in the punch and hence the rivet. In particular, ultrasonic vibrations with a vibration amplitude (distance between maximum positive and negative amplitude of a vibration) of between 10 pm and 110 pm (corresponding to an amplitude of 5 pm to 55 pm) and a freguency of between 15 kHz and 35 kHz or optionally even higher can be generated by means of the vibration generator 32. The vibration generator 32 is connected to the computer unit 80 (or may also be part of the computer unit) and can be controlled by the latter.

The drive 50 may be a drive with a ball screw, roller screw, planetary screw or threaded screw drive or similar for example, which is capable of applying a force F for driving the rivet 20 into the components 11, 12. Mounted on the drive 50 is a retaining device 35, for example in the form of a frame or a support. Disposed on the retaining device 35 is a vibration system 39 which in this instance comprises the vibration convertor 30, a booster 31 as well as the punch or sonotrode 15 and the clamp 16.

During operation of the self-pierce riveting device 10, in other words during so-called ultrasonic self-pierce riveting, a lateral migration or bending or shifting of the joining tool may occur due to the high-frequency longitudinal vibration of the joining tool, i.e. sonotrode 15, booster 31 and vibration convertor 30. This is caused by high lateral transverse forces which can occur due to a hammering or percussive movement of the punch 15 on the rivet 20 or due to a vibrating motion of the punch 15 in permanent contact with the rivet 20, in each case in combination with the slightest unevenness (such as for example component radii, uneven sheets, inadequately adjusted or set tool alignment, bending of the support or frame, unsymmetrical design of the support and such like) and can have a negative effect on the service life of the tool and quality of the joining point.

Such transverse forces are denoted by F_Q in Figure 2 by way of example. Furthermore, tilting of the joining tool or the entire vibration system 39 is also graphically illustrated in Figure

2. In the case of conventional self-pierce riveting devices known to date (that are not assisted by vibration or ultrasound systems) such transverse forces are unknown on this scale because the joining tool is not subjected to high-frequency longitudinal vibrations.

Figure 3 schematically illustrates a self-pierce riveting

device 10'	proposed by the invention based on a preferred
embodiment.	The self-pierce riveting device 10' substantially
corresponds	to the self-pierce riveting device 10 illustrated

in Figure 2 in terms of its components and its design but additionally has a guide device 70 which will be explained in more detail below. Reference may otherwise be made to the explanations relating to Figure 2 which apply in this instance accordingly.

In this instance, an additional guide device 70 is provided on the C-frame 60 as a guide rail, for example in the form of a linear or profiled guide or linear or profiled guide rail system, as a result of which the joining tool is unaffected by the high transverse forces which occur (these lie within a range of up to 5 kN depending on the material thickness combination to be riveted) and the coaxial alignment of the joining tools is guaranteed before, during and after the joining process.

The guide device 70 in this instance is disposed on and secured to the leg 61 of the frame 60 on which the drive 50 is also disposed. The supporting tool 18, on the other hand, is disposed on the oppositely lying leg 62. The vibration system 39 and/or joining tool in this instance is retained on the guide device 70 indirectly by the holder 35 and can be guided in the joining direction R. Appropriate (linear) slide elements, slide bearings, roller bearings or similar, for example, may be provided for this purpose.

Furthermore, the guide device 70 enables a different weight distribution to be obtained on the two arms, in other words the two legs 61 and 62, which occurs due to the relatively heavy drive 50 and the usually likewise relatively heavy vibration system 39 on the one leg and prevents any resultant shifting of the tool, and any lifting of the integrated components due to rapid acceleration or deceleration of the robots (see Figure 1) is reduced to a minimum when the C-support or C-frame is being moved into different spatial positions and positioned on the component.

The illustrated self-pierce riveting device 10' is also provided with a position measuring system 71, in particular on the guide rail or guide device 70. It operates particularly accurately because of the guide rail and correspondingly good resultant measurement signals can also be integrated in an operation of the self-pierce riveting device for example, in particular for control or regulation purposes, so that no unnecessary or non-critical shifting of the tools is permitted from the outset. To this end, the measurement signals may be transmitted to the computer unit 80 for example.

Figure 4 provides a schematic illustration of a self-pierce riveting device 10'' proposed by the invention based on another preferred embodiment. The self-pierce riveting device 10'' substantially corresponds to the self-pierce riveting device 10' illustrated in Figure 3 in terms of its components and its design but in this instance a guide device 70' is provided which is disposed between the two legs 61 and 62 of the frame 60 on which the drive 50 and supporting tool 18 are disposed.

The guide device 70', which is also a guide rail in this instance, is attached to the frame 60 or to the so-called support back 63 at selected points for example by means of two connecting elements. However, it would also be conceivable for the guide device

70' not to be attached to the frame 60 by selected points but in a flat arrangement, in other words by means of an entire side or surface which extends along the joining direction R and is directed towards the frame 60.

In this case, the frame 60 might be of a slightly different design, for example with shorter legs.

Alternatively or in addition, the guide device might also be of larger dimensions, for example. The effect of the guide device 70' nevertheless corresponds to that of the guide device 70 illustrated in

Figure 3.

Otherwise, illustrated provided. instance .

a position measuring system 71 such as and described with reference to Figure 3 is These explanations apply accordingly in that also this

Claims

1. Self-pierce riveting device (10', 10'') for joining at least two components (11, 12) by means of a rivet (20), having a punch (15) and a supporting tool (18) between which the at least two components (11, 12) and the rivet (20) can be positioned, having a drive (50) which is disposed on a frame (60) of the self-pierce riveting device (10) and by means of which a force can be applied to the punch (15) in the joining direction (R), having a vibration system (39) which is attached can be moved relative to the frame (60) by means of the drive and which is coupled in such and which comprises the punch (15), can be coupled with a vibration a way that it is driven into the at or can be made to vibrate as least two components (11,

12), characterised by a guide device (70, 70') which is mounted on the frame (60) and on which the vibration system (39) is indirectly or directly retained and can be guided in the joining direction (R).

2. Self-pierce riveting device (10', 10'') as claimed in claim 1, wherein the vibration system (39) is secured to the drive (50) by means of a retaining device (35) and is retained on and can be guided on the guide device (70, 70').

3. Self-pierce riveting device (10') as claimed in claim 1 or 2, wherein the frame (60) is provided in the form of a C-frame and wherein the guide device (70) is disposed on a leg (61) of the frame on which the drive (50) is also disposed.

4. Self-pierce riveting device (10'') as claimed in claim 1 or 2, wherein the frame (60) is provided in the form of a Cframe and wherein the guide device (70') is disposed between two legs (61, 62) of the frame on which the drive (50) and the supporting tool (18) are disposed.

5. Self-pierce riveting device (10', 10'') as claimed in one of the preceding claims, wherein the guide device (70, 70') is provided in the form of a profiled guide or a linear guide.

6. Self-pierce riveting device (10', 10'') as claimed in one of the preceding claims, wherein a vibration direction of the vibration system (39) is oriented in the joining direction (R).

7. Self-pierce riveting device (10', 10'') as claimed in one of the preceding claims, wherein the vibration system (39) has a vibration convertor (30) with which the vibration generator (32) is coupled and which is connected to a sonotrode which comprises the punch (15).

8. Self-pierce riveting device (10', 10'') as claimed in

claim 7, wherein the vibration system (39) also has a booster (31) via which the vibration convertor (30) is connected to the sonotrode.

9. Self-pierce riveting device (10', 10 ' ' ) as claimed in one of the preceding claims, wherein the guide device (70, 70 ' ) is provided as a guide rail.

10. Self-pierce riveting device (10', 10 ' ' ) as claimed in one

of the preceding claims, further comprising a position measuring system (71) by means of which a movement and/or a position of the vibration system (39) relative to the guide device (70, 70') can be determined.

Intellectual Property Office

Application No: GB1903215.0

Claims searched: 1-10

Examiner: Tim James

Date of search: 18 June 2019

Patents Act 1977: Search Report under Section 17

Documents considered to be relevant:

Category Relevant to claims Identity of document and passage or figure of particular relevance X 1, 2 and 4-9 US3483611 A (CAVITRON) see the figures and the paragraph bridging columns 4 and 5 X 1-3, 5, 6, and 9 US1430692 A (SENG) see figure 1 especially hammer 7 and hammer guide rod 21, and page 1 lines 76-81

Categories:

X Document indicating lack of novelty or inventive step A Document indicating technological background and/or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of before the filing date of this invention. same category. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.

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