EP3120951B1 - Self-piercing rivet device and production device - Google Patents

Description

description

The present invention relates to a punch riveting device for connecting at least two components and a manufacturing device with such a punch riveting device.

State of the art

Methods and devices for punch riveting are used to connect at least two components (joining partners) that have just been formed in a connection area. A punch riveting process is characterized in that it is not necessary to prepunch the components to be connected to one another. Rather, a rivet is pressed into the at least two components by means of a stamp or a stamping tool, whereby a correspondingly shaped counter-holder, for example in the form of a die, which interacts with the stamping tool, ensures that the rivet is fixed in a certain way deformed within the components to be connected to one another in order to produce a non-positive and positive connection between the components and at the same time to prevent penetration of the component facing away from the rivet.

Furthermore, for example EP 2 318 161 B1 or the WO 2010/012973 A1 or the DE 10 2014 203 357 A1 So-called ultrasonic punch riveting methods or devices are known in which an oscillation generator, such as an ultrasound generator, is used to set one or more components in vibration when the components are connected. This vibration reduces, for example, the force required to press in the rivet.

From the EP 0 890 397 A1 , which forms the basis of the preamble of claim 1, a joining device is known in which an impact mechanism is used to introduce the joining force into the joining connection in impacts. An elastically suspended large mass is used for vibration isolation.

Disclosure of the invention

According to the invention, a punch riveting device according to claim 1 and a production device according to claim 12 are proposed. Advantageous embodiments are the subject of the subclaims and the following description.

Advantages of the invention

A punch riveting device according to the invention is used to connect at least two components and has a punch, a counter-holder, a hold-down device and a vibration generator. The punch, the hold-down and the counter-holder are arranged in relation to one another in such a way that the at least two components can be arranged between the stamp and the counter-holder and at the same time between the hold-down and the counter-holder. The stamp and the vibration generator are coupled to one another and form a vibration system and a drive is provided to which the stamp and the hold-down device are coupled such that a force can be exerted on the stamp and on the hold-down device in the direction of the components by means of the drive. The hold-down device is coupled to the vibration system in such a way that an oscillation amplitude of the hold-down device in the contact area with one of the components has at most 25%, in particular at most 10%, of an oscillation amplitude of the punch in the contact area with a rivet. In other words, the hold-down device is thus coupled to the vibration system in such a way that only the smallest possible, preferably no, vibration can be transmitted from the vibration system to the hold-down device. The vibration amplitude of the hold-down device in the contact area with one of the components is preferably 0% (i.e., vibration node) of the vibration amplitude of the punch in the contact area with the rivet, or no vibration can be transmitted from the vibration system to the hold-down device. Both a so-called semi-hollow rivet and a so-called full rivet can be used as the rivet.

In conventional punch riveting devices without a vibration generator, a drive can be provided in a simple manner, which at the same time exerts a force on the punch a rivet into the components and can exert a force on the hold-down device for pressing the components against the counter-holder. In the case of a punch riveting device with a vibration generator, in which the punch is made to vibrate while the rivet is being pressed in, the hold-down device can also be set in motion, whereby the desired pressing force on the components is reduced by the hold-down device. This can lead to poor riveting results or reduce the effect of vibration coupling or even completely hinder it. While separate drives can be provided for the punch and the hold-down device to solve this problem, a punch riveting device according to the invention manages with only one drive. This is possible because the hold-down device is suitably coupled to the vibration system formed by the vibration generator and punch, whereby the punch is set in vibration as desired, but the hold-down device is not. In this way, a punch riveting device with only one drive can be provided, which is therefore simple and inexpensive.

According to the invention, the hold-down device is coupled to the oscillation system in a region of the oscillation system in which an oscillation amplitude of the oscillation system has at most 10%, in particular at most 5%, of the oscillation amplitude of the punch in the contact region with the rivet. In other words, the hold-down device is coupled to the oscillation system in a region of the oscillation system in which an oscillation of the oscillation system has the smallest possible amplitude. The oscillation amplitude of the oscillation system in this region is preferably 0% (ie oscillation node) of the oscillation amplitude of the punch in the contact region with the rivet. Such an oscillation system generally also has a booster and / or a sonotrode, in particular also only one sonotrode, via which the stamp is coupled to the oscillation generator. In particular, the stamp can also be designed as part of the sonotrode. An oscillation is generated by the oscillation generator and the amplitude of the oscillation is translated via the booster. Depending on the geometrical design, the amplitude can be reduced, passed on consistently, but usually translated and therefore increased. Like the booster, the sonotrode forms a resonance body, in which the amplitude is usually further increased. Overall, a standing longitudinal vibration is formed in the vibration system. This standing vibration therefore also has points or ranges in which the amplitude is zero or at least almost zero. If the hold-down device is now coupled to the vibration system in such an area of the vibration system, none will be or almost no vibration is transmitted to the hold-down device. A uniform force can thus be exerted on the components. It it goes without saying that the corresponding areas depend on the design of the vibration system.

A holding device is advantageously provided, which is fastened to the drive and to which the vibration system is fastened. In particular, the holding device at least partially surrounds the vibration generator. Such a holding device enables a particularly simple and space-saving arrangement of the vibration system in the punch riveting device. In particular, the vibration system can also be largely decoupled from the drive with regard to vibration transmissions in this way.

It is advantageous if the hold-down device is fastened to the holding device separately from the vibration system. Thus, both the vibration system and the hold-down device are attached to the holding device and via the holding device to the drive. This enables a power transmission from the drive to the punch and the hold-down device. However, the separate attachment of the vibrating system and hold-down device to the holding device means that there is no direct contact between the vibrating system and holding-down device, but there is only indirect contact via the holding device, which can also be kept low with a suitable design of the holding device. In this way, vibration transmission from the vibration system to the hold-down device is largely avoided. If the oscillation system is also attached to the holding device in an area of the oscillation system in which an oscillation of the oscillation system has an amplitude that is as small as possible, in particular none, an oscillation transmission to the hold-down device is further reduced. As an alternative or in addition, care can be taken to ensure that the vibration system is fastened to the holding device near the vibration generator or far from the stamp, since here an amplitude is generally significantly lower than in the region of the stamp.

Alternatively, it is preferred that the hold-down device is coupled to the vibration system in a region of the punch in which an oscillation amplitude of the vibration system has at most 10%, in particular at most 5%, of the vibration amplitude of the punch in the contact area of the rivet. In other words, the hold-down device is coupled to the vibration system in a region of the plunger in which an oscillation of the vibration system has the smallest possible amplitude. The oscillation amplitude of the oscillation system is preferably 0% (ie Vibration node) of the vibration amplitude of the punch in the contact area with the rivet. This is possible because, as a rule, an area also occurs in the stamp in which the standing vibration already mentioned has no or at least almost no amplitude. If the hold-down device is coupled here, the hold-down device can be made very compact because the punch is close to the components.

The hold-down device preferably has a spring unit, via which it is coupled to the vibration system. In this way, the relative movement between the punch and the holding-down device can be taken into account due to the lowering of the punch when the rivet is pressed in, while at the same time the force from the drive acts on the holding-down device. In the case of a suitable coupling of the hold-down device to the holding device or to the punch, the spring unit can have, for example, a cylindrical helical compression spring or plate springs or an elastomer spring. A vibration or sound-absorbing coating such as a suitable lacquer can also be provided on the hold-down device, in particular in an area to which the hold-down device is coupled to the vibration system or other components. Vibrations of the hold-down device can thus be reduced. A hold-down force can be adjusted while the rivet is being pressed in using a spring stiffness or a spring constant. Taking into account the force applied by the drive, the spring constant can be selected appropriately so that hold-down forces between 2 kN and 8 kN are obtained, for example. In particular, it can also be taken into account in the course of the hold-down force during the pressing in that the spring constant, for example, runs linearly in the case of a cylindrical helical compression spring, degressively in the case of disc springs or progressively in the case of pressure-loaded elastomer springs.

The spring unit advantageously has a damping material which is suitable for reducing an amplitude of the vibrations generated by the vibration generator at least to half. In particular, the spring unit can be, for example, an elastomer spring, ie an elastic material that transmits the linear movement of the drive, but not the generally high-frequency vibration generated by the vibration generator. Instead of an elastomer spring, a damping material, for example an elastomer, can also be used in addition to a conventional spring.

It is advantageous if the ultrasound generator is designed as a piezo converter. This is a simple method for generating vibrations.

The oscillation system expediently also has a booster and / or a sonotrode, via which the stamp is coupled to the oscillation generator. In particular, the stamp is designed as part of the sonotrode. This is a common and easy-to-use arrangement for a vibration system for a punch riveting device.

The punch riveting device expediently also has a frame which has an interface for attaching the punch riveting device to a production device, such as an industrial robot. This enables a very simple assembly, for example, as part of an exchange.

A manufacturing device according to the invention has a punch riveting device according to the invention.

To avoid repetition, reference is made to the above statements regarding the punch riveting device according to the invention with regard to further advantages of a manufacturing device according to the invention.

Further advantages and refinements of the invention result from the description and the accompanying drawing.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own without departing from the scope of the present invention.

The invention is illustrated schematically in the drawing using exemplary embodiments and is described in detail below with reference to the drawing.

figure description

Figure 1

shows a simplified and schematic of a manufacturing device according to the invention in a preferred embodiment.

Figures 2a to 2d

show a punch riveting device in various phases of performing a punch riveting process.

Figure 3

shows schematically a punch riveting device without vibration generator.

Figures 4a and 4b

schematically show punch riveting devices according to the invention in various preferred embodiments.

Detailed description of the drawing

In Figure 1 a simplified embodiment of a manufacturing device 100 according to the invention is shown in a preferred embodiment. The manufacturing facility 100 can be, for example, an industrial robot in a manufacturing hall, for example, for an automobile body shop.

The production device 100 in this case has a support structure 3 arranged on a floor and two arms 4 and 5 which are arranged on it and are connected to one another and movable. At the end of the arm 5, a punch riveting device 10 'according to the invention is arranged, which in the Figures 3a to 3d is described in more detail.

Furthermore, a computing unit 80 is shown, which is, for example, a control unit for the punch riveting device 10 '. The computing unit 80 can also act as a control unit for the entire production facility, i.e. In addition to the punch riveting device, it can also be provided for the control of the movable arms. Display means 90, for example a display, are also provided, on which, for example, current operating parameters of the punch riveting device can be displayed.

In the Figures 2a to 2d is shown schematically and simplified a punch riveting device 10 according to the invention in different phases of the punch riveting method. The Punch riveting device 10 has a punch 15 which, for example, has a round cross section.

The punch 15 is radially surrounded by a sleeve-shaped hold-down device 16 and is arranged to be movable in the longitudinal direction relative to the latter. In particular, the punch 15 is coupled to a drive (not shown here), for example a hydraulic or pneumatic drive, which is used to apply a force F required to press a rivet 20 into the two components 11, 12.

The hold-down device 16 is also designed to press against the surface of the component 11 facing the die 15 with a hold-down force. For this purpose, a separate drive can be provided, for example. However, the hold-down device can also be coupled to the drive of the plunger 15, for example by means of a spring.

On the side of the two components 11, 12 opposite the punch 15 and the holding-down device 16, a die 18 acting as a counter-holding device is arranged. The die 18 can also be raised and lowered in the direction of a longitudinal axis 19, in the direction of which the punch 15 and the hold-down device 16 are also arranged to be movable. The hold-down device 16 and the die 18 serve to clamp or compress the two components 11, 12 between the hold-down device 16 and the die 18 during processing by the punch 15. The die 18 has a flat upper side 21 on the side facing the component 12, from which a trough-shaped or cowl-shaped recess 22 extends. The matrix recess can be flat, conical or spherical or a dome or. Have a thorn in the middle of the recess.

The rivet 20, here a semi-hollow rivet, for example, preferably consists of a material that is harder than the materials of the two components 11, 12, at least in the region of the rivet shank 24. The flat top 26 facing away from the component 11 is arranged in operative connection with the punch 15 which lies flat against the top 26 of the rivet 20. Thus, the top 26 of the rivet represents a contact point 27 between the rivet and the punch.

The stamp 15 is operatively connected to an oscillation generator 30 for generating oscillations or vibrations. In particular, by means of the vibration generator 30 ultrasonic vibrations with a vibration range (distance between the maximum positive and negative amplitude of a vibration) between 10 µm and 110 µm (corresponds to an amplitude of 5 µm to 55 µm) and a frequency between 15 kHz and 35 kHz or possibly higher.

These vibrations 15 are coupled into the rivet 20 by the vibration generator 30 via the punch 15. The direction of coupling of the vibrations of the vibration generator 30 can take place, for example, parallel to the longitudinal axis 19, that is to say parallel to the joining direction of the rivet 20 into the components 11, 12. The vibration generator 30 is connected to the computing unit 80 and can be controlled by the latter.

In the Figure 2a The phase shown represents a start of the punch riveting process, in which the rivet shaft 24 comes into operative connection with the upper side of the component 11. The punch 15 is pressed with the force F against the component 11 facing the punch 15.

In one in Figure 2b shown further phase, ie during the further course of the riveting process and with the support of the vibrations coupled into the components 11, 12, the rivet shaft 24 initially cuts or punches itself into the component 11. The two components 11, 12 are plastically deformed, the component 12 facing the recess 22 being pressed into the recess 22 in the corresponding areas.

During the further movement path or the further downward movement of the rivet 20 according to the Figure 2c the projections or the rivet shaft 24 are spread outwards in the region of the recesses 22, as a result of which the two components 11, 12 are securely connected to one another in a positive and non-positive manner in the axial direction.

It is essential that according to the Figure 2d , which shows the end position of the rivet 20, the rivet shaft 24 does not protrude from the component 12 or does not penetrate it completely.

After the rivet 20 in the Figure 2d has reached the end position shown, in which the upper side 26 of the rivet 20 is at least approximately flush with the upper side of the component 11 completes, the stamp 15 is then moved upwards by the components 11, 12 in the opposite direction.

In Figure 3 is shown schematically and simplified a punch riveting device without vibration generator. Compared to those in the Figures 2a to 2d The punch riveting device shown here shows the coupling of the hold-down device 16 to the punch 15.

The stamp 15 has a radial projection at the upper end shown here. A spring unit 41, for example in the form of a cylindrical helical compression spring, is attached to this radial projection, via which the hold-down device 16 is coupled to the plunger 15.

If a force F is now exerted on the punch 15 to press in the rivet 20 via a suitable drive, the force is simultaneously exerted on the hold-down device 16, by means of which the components 11, 12 are pressed against the counter-holder or the die 18, the relative movement between the punch 15 and the hold-down device 16 is taken into account by the spring unit 41.

It can be seen from the arrangement of punch and hold-down device shown that this arrangement is unsuitable for a punch riveting device with a vibration generator, since the vibrations would not only be transmitted to the punch but also to the hold-down device. The components 11, 12 would not be pressed satisfactorily against the counter-holder 18 with an oscillating hold-down device.

In Figure 4a A punch riveting device 10 'according to the invention is now shown in a preferred embodiment. The punch riveting device 10 'has a frame 60, which is preferably in the form of a C-frame or C-bracket, on which the individual components in a punch riveting device are generally arranged in order to be able to assume the desired position relative to one another. Via the frame 60, the punch riveting device 10 ′ can, for example, on the Figure 1 arm 3 shown be attached. It goes without saying that even in the Figures 2a to 2d and 3 Punch riveting devices shown can usually be such a frame.

Furthermore, a drive 50 is shown, which can be, for example, a spindle drive or the like, which is suitable for applying a force F for pressing the rivet 20 into the components 11, 12. A holding device 35, for example in the form of a frame or a frame, is attached to the drive 50. An oscillation system 39 is arranged on the holding device 35, which in the present case has an oscillation generator 30, for example an ultrasound generator, a booster 31, a sonotrode 32 and a stamp 15.

As can be seen from the figure, the oscillation system 39 is arranged or fastened to the holding device 35 approximately in the middle of the booster 31, which has an upper, wider and a lower, narrower part. It should be noted here that the stamp 15 can, for example, be part of the sonotrode 32, i.e. that both components can form a structural unit. Although the booster 31 is connected to the holding device 35, the booster 31 has no (i.e., vibration node) or only a small vibration amplitude in the region where it is connected to the holding device 35.

Furthermore, a hold-down device 16 'is shown, which is coupled to the holding device 35 by means of a spring unit 41, for example in the form of a cylindrical helical compression spring. The hold-down device 16 'is thus coupled to the holding device 35 separately from the oscillation system 39, i.e. the hold-down device 16 'is only indirectly coupled to the vibration system 39. An oscillation of the oscillation system 39 is not, or at least only insignificantly, transmitted to the hold-down device 16 'by this type of coupling.

Furthermore, a diagram is shown on the right-hand side of the figure, in which a course of an oscillation amplitude A of an oscillation which forms in the oscillation system 39 is shown over the position λ. It can be seen that the area at which the vibration system 39 is coupled to the holding device 35 is a point of low vibration amplitude. In addition, in this, here the upper, region of the oscillation system 39, the oscillation amplitude is generally lower than in the lower region of the plunger 15. In this respect, a possibly nevertheless transmissible oscillation has hardly any effect on the hold-down device, since the oscillation amplitude would be very low.

In Figure 4b A punch riveting device 10 'according to the invention is shown in a further preferred embodiment. Opposite the in Figure 4a Punch riveting device 10 'shown the hold-down device 16 'is not coupled to the holding device 35, but to the oscillation system 39 in the area of the plunger 15 or the sonotrode 32.

From the diagram on the right-hand side in the figure, which in turn shows a course of an oscillation amplitude A of an oscillation forming in the oscillation system 39 over the position λ, it can be seen that the hold-down device 16 'by means of the spring unit 41 in one area , here at the upper end of the stamp 15, of the vibration system 39 is coupled, in which the vibration amplitude is very low, if possible zero. In the present case, the spring unit 41 is attached to a component 42, which in turn is attached in the relevant area of the stamp 15.

Such a suitable range with little or no vibration amplitude can be determined, for example, on the basis of the design of the vibration system 39 or by means of tests. By coupling the hold-down device 16 'to the vibration system 39 in this way, no or at least almost no vibrations are transmitted from the vibration system 39 to the hold-down device 16'.

Claims (12)

1. Punch riveting device (10') for connecting at least two components (11, 12), having a punch (15), a dolly (18), a holding-down means (16') and a vibration generator (30), wherein the punch (15), the holding-down means and the dolly (18) are arranged with respect to one another such that the at least two components (11, 12) are arrangeable between the punch (15) and the dolly (18) and at the same time between the holding-down means (16') and the dolly (18), wherein the punch (15) and the vibration generator (30) are coupled together and form a vibrating system (39), wherein a drive (50) is provided, to which the punch (15) and the holding-down means (16') are coupled such that, by means of the drive (50), a force (F) is able to be exerted on the punch (15) and on the holding-down means (16') in the direction of the components (11, 12), characterized in that the vibration generator (30) is configured as an ultrasound generator, wherein the holding-down means (16') is coupled to the vibrating system (39) such that a vibration amplitude (A) of the holding-down means (16') in the contact region with one of the components exhibits at most 25%, in particular at most 10%, of a vibration amplitude (A) of the punch (15) in the contact region with a rivet (20), wherein the holding-down means (16') is coupled to the vibrating system (39) in a region of the vibrating system (39) in which a vibration amplitude (A) of the vibrating system (39) exhibits at most 10%, in particular at most 5%, of the vibration amplitude (A) of the punch (15) in the contact region with the rivet (20).
2. Punch riveting device (10') according to Claim 1, wherein a holding device (35) is provided, which is fastened to the drive (50) and to which the vibrating system (39) is fastened.
3. Punch riveting device (10') according to Claim 2, wherein the holding device (35) at least partially surrounds the vibration generator (30).
4. Punch riveting device (10') according to Claim 2 or 3, wherein the holding-down means (16') is fastened to the holding device (35) separately from the vibrating system (39).
5. Punch riveting device (10') according to one of Claims 1 to 4, wherein the holding-down means (16') is coupled to the vibrating system (39) in a region of the punch (15) in which a vibration amplitude (A) of the vibrating system (39) exhibits at most 10%, in particular at most 5%, of the vibration amplitude (A) of the punch (15) in the contact region with the rivet (20).
6. Punch riveting device (10') according to one of the preceding claims, wherein the holding-down means (16') has a spring unit (41), via which it is coupled to the vibrating system (39).
7. Punch riveting device (10') according to Claim 6, wherein the spring unit (41) exhibits a damping material, in particular an elastomer, which is suitable for reducing an amplitude of the vibrations generated by the vibration generator at least to half.
8. Punch riveting device (10') according to one of the preceding claims, wherein the vibration generator (30) is configured as a piezo converter.
9. Punch riveting device (10') according to one of the preceding claims, wherein the vibrating system (39) also has a booster (31) and/or a sonotrode (32), via which the punch (15) is coupled to the vibration generator (30).
10. Punch riveting device (10') according to Claim 9, wherein the punch (15) is configured as part of the sonotrode (32).
11. Punch riveting device (10') according to one of the preceding claims, also having a frame (60), which has an interface for attaching the punch riveting device (10') to a production facility (100).
12. Production facility (100) having a punch riveting device (10') according to one of the preceding claims.

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