EP3332886B1 - Method and assembly for monitoring self-piercing riveting - Google Patents

Description

The present invention relates to a method and a production device with an arrangement for monitoring a punch riveting device, in which at least one component participating in the pressing of a rivet into components to be connected is set in vibration upon pressing, and a production device with such an arrangement.

State of the art

Riveting serve to connect at least two in a connection region in particular flat trained components (joint partner). A punch riveting method is characterized, for example, by the fact that pre-punching of the components to be joined together is not required. Instead, a rivet is pressed into the at least two components by means of a joining tool comprising a punch, it being possible to ensure that the rivet or the components by a correspondingly shaped counter-holder, for example in the form of a die, which cooperates with the joining tool deform in a certain way to produce a positive and positive connection between the components.

Furthermore, for example, from the EP 2 318 161 B1 a so-called ultrasonic punch riveting method in which a vibration generator, such as an ultrasonic generator, is used to cause one or more components to vibrate when connecting the components. By this vibration, for example, the expended force is reduced to push the rivet.

Further punch riveting devices that use the coupling of vibrations or vibrations, for example, from EP 0 890 397 A1 , the DE 10 2016 002 172 A1 , the WO 2006/110089 A1 and the EP 3 117 923 A1 known.

Disclosure of the invention

According to the invention, a method and a production device with an arrangement for monitoring a punch riveting device with the features of the independent patent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

A method according to the invention serves to monitor a punch rivet device which serves to connect at least two components by means of a rivet and during which during at least one operating phase at least one component involved in pressing in the rivet into the at least two components is set in vibration by means of a vibration generator. Such a punch rivet device generally has a joining tool with a punch, by means of which the rivet is pressed into the components. Here then usually a drive is provided, by means of which a necessary force for introducing the rivet on the joining tool can be exercised. As a rule, a counter-holder, for example in the form of a die, is also provided on the side of the at least two components opposite the joining tool. As a vibration generator is in particular a sound generator, in particular an ultrasonic generator, into consideration. In particular, the rivet and / or the punch and / or the counter-holder and / or at least one of the at least two components come into consideration as the at least one component involved in pressing in the rivet which is set in vibration. It is conceivable in the case of the stamp as that component which is vibrated, that the punch is used or designed as sonotrode simultaneously and is connected via a booster with a vibration converter, which in turn is connected to the vibration generator.

During the at least one operating phase, that is, during which the at least one component, such as, for example, the stamp is vibrated and thus oscillates, at least temporarily within a predetermined local distance range from the punch riveting device, at least one variable characteristic of a sound pressure is generated determined. In particular, a sound pressure and / or a sound pressure level, in each case in air, come into consideration as such a characteristic variable. With regard to the local distance range, it should be noted that the variables mentioned depend on a distance of a corresponding sound-measuring device to the source of the sound, that is to say in particular the oscillated component or other components oscillating thereby. In this respect, it is expedient that the at least one characteristic of the sound pressure Size near the punch rivet, for example, with a maximum distance of 1 m, 2 m or 3 m, is detected. A corresponding evaluation can then also be carried out remotely. For detecting the at least one variable characteristic of the sound pressure, a microphone can preferably be used, but other sound measuring devices for detecting the respective size are also conceivable. A determination or evaluation can then take place in a separate evaluation unit.

A punch riveter with vibration coupling, in particular an ultrasonic punch riveting device, allows over conventional punch riveting a reduction of the force used to push the rivet, since the impressions is facilitated by the vibrations. Overall, in particular weight can be saved in the punch riveting.

By the proposed method can now also in such a punch riveting also, for example, a necessary occupational safety, in particular with regard to possible violations of prescribed limits for the sound pressure or the sound pressure level are met, which may possibly occur due to the vibration generation and vibration coupling. The proposed method thus makes it possible to monitor the process noise occurring during operation and also opens up possibilities for countermeasures.

By way of example, it is preferred here that, if the at least one variable characteristic of the sound pressure exceeds a predetermined limit value, a warning message is output and / or an operation of the stamped riveting device is changed, in particular terminated. A conceivable limit value for the sound pressure level is, for example, 85 dB for a customary listening range between, for example, 1 and 20 kHz, as is usually required in production halls. However, lower limit values are also conceivable, for example 83 dB or 81 dB. This can be automated in particular and thus very quickly. As warning messages come here, for example, acoustic and / or visual warning messages into consideration. When the operation changes, for example, a reduction in the power of the coupled oscillation and / or a frequency change is considered or a suspension of the operation. In particular, the measures can also take place only intermittently. A termination of the operation comes in particular as the last stage in Consider, for example, if other measures do not lead to the limit being exceeded. In this way, so the work safety can be guaranteed.

Preferably, a time profile of the at least one variable characteristic of the sound pressure and / or a progression of the at least one characteristic of the sound pressure with respect to a position of a component used to press in the rivet are determined and in particular also recorded. In particular, the stamp is considered as the component used to push in the rivet. On the basis of such a course, in addition to a possible analysis of the process noise, it is also possible to make analyzes of the course of the process itself or the punch riveting apparatus. In addition, this also gives the possibility to determine the number of punch riveting operations.

Advantageously, the profile of the at least one variable characteristic of the sound pressure can be used for a quality evaluation of an associated punch riveting operation and / or a connection of the at least two components produced in this punch riveting operation. Thus, an assessment and also a subsequent tracking of the connections generated by the punch riveting apparatus are possible.

It is also advantageous if the course of the at least one variable characteristic for the sound pressure is used for a check of a functionality of the punch riveting device or at least one component of the punch riveting device. It is conceivable, for example, that any functional limitations or defects of the drive or the stamp are detected, as this may change the characteristics or the course of the sound pressure or the sound pressure level.

It is also useful in determining the course if a frequency range between 1 and 80 kHz is recorded or recorded. Although ultrasound is not perceptible to humans or at least not acoustically perceptible, the above mentioned assessments can nevertheless be made. For this purpose, it should also be noted that, for example, values between 15 and 35 kHz are preferred as the typical frequency for generating the oscillations, but it is also possible to form harmonics with correspondingly higher frequencies.

The at least one variable that is characteristic of the sound pressure is preferably determined using a sound-measuring device which is arranged on the punch riveting device, in particular on a frame or a setting unit of the punch riveting device. In this case, a drive unit and the joining tool, possibly also other associated components such as the booster and the vibration generator, can be understood as a set unit. The local distance from the punch riveting device is then zero. In this way it can be achieved that the values for the corresponding size are comparable with one another, since the same distance to the sound source is always used. This is particularly advantageous insofar as the punch riveting apparatus is usually moved during its use, for example by means of a robot arm

The detected by the sound measuring device, at least one characteristic of the sound pressure size can then preferably wired, for example by means of USB cable, or wireless, for example by means of Bluetooth or WLAN, are transmitted to an evaluation. While at the same time a power supply of the sound-measuring device can be provided in the wired version, exist in the wireless variant more options for the positioning of the sound-measuring device, since no cable must be laid.

Advantageously, the sound-measuring device is at least partially supplied by means of energy harvesting with energy for operation. This is advantageous in particular in the case of the wireless connection to the evaluation unit, since it is expedient to provide an energy store such as a rechargeable battery or a battery. Under energy harvesting is to be understood that small amounts of electrical energy from one or more sources such as vibrations, individual impulses or solar energy can be obtained. In this way, a particularly energy-efficient operation is possible.

In a production device according to the invention with a punch riveting device and arrangement, the arrangement for monitoring the punch rivet device serves to connect at least two components by means of a rivet and during at least one operating phase at least one component involved in pressing the rivet into the at least two components when pressing in by means of a Vibration generator is set in oscillation. In this case, a sound-measuring device for detecting at least one characteristic of a sound pressure size within a vorbestimm The local distance range is set by the punch riveting device, and an evaluation unit is provided for the detected variable, which is at least one variable that is characteristic of the sound pressure. This production device preferably also has means suitable for carrying out a method according to the invention.

With regard to further embodiments and advantages of the arrangement according to the invention as well as the detailed explanation of the punch riveting device, reference is made to the above statements on the method according to the invention to avoid repetition, which apply accordingly here.

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

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

The invention is illustrated schematically with reference to an embodiment in the drawing and will be described in detail below with reference to the drawing.

Figur 1

zeigt vereinfacht und schematisch eine erfindungsgemäße Fertigungseinrichtung mit einer Stanznietvorrichtung in einer bevorzugten Ausführungsform.

Figur 2

zeigt schematisch eine detailliertere Darstellung der Stanznietvorrichtung aus Figur 1.

Figur 3

zeigt einen Verlauf eines Schalldruckpegels, wie er bei einem erfindungsgemäßen Verfahren in einer bevorzugten Ausführungsform auftreten kann.

Figur 4

zeigt einen Verlauf eines Schalldrucks, wie er bei einem erfindungsgemäßen Verfahren in einer weiteren bevorzugten Ausführungsform auftreten kann.

figure description

FIG. 1

shows simplified and schematically a manufacturing device according to the invention with a punch riveting in a preferred embodiment.

FIG. 2

schematically shows a more detailed representation of the punch rivet apparatus of Figure 1.

FIG. 3

shows a profile of a sound pressure level, as it can occur in a method according to the invention in a preferred embodiment.

FIG. 4

shows a course of a sound pressure, as it can occur in a method according to the invention in a further preferred embodiment.

Detailed description of the drawing

In FIG. 1 is simplified and schematically illustrated a manufacturing device 100 according to the invention in a preferred embodiment. The production device 100 may be, for example, an industrial robot in a production hall, for example for an automobile body shop.

In this case, the production device 100 has a carrier structure 3 arranged on a base and two arms 4 and 5 arranged thereon and connected to one another and movable. At the end of the arm 5, a punch rivet 10 is arranged, which will be described in more detail below.

Furthermore, a computing unit 80 is shown, which is, for example, a control unit for the joining device 10. The arithmetic unit 80 may also be used as a control unit for the entire manufacturing facility, i. be provided in addition to the punch riveting especially for the control of the movable arms. Furthermore, display means 90, for example a display, are provided on which, for example, current operating parameters of the punch riveting apparatus can be displayed. The element 90 may also be a combined display / input means, e.g. a touchscreen, act.

Furthermore, a sound-measuring device 81 for detecting at least one characteristic of a sound pressure size at the punch riveting 10 is arranged. Values detected by the sound measuring device 81 can be transmitted to the arithmetic unit 80, which at the same time comprises or represents an evaluation unit by means of which the detected values can be evaluated.

In FIG. 2 schematically a punch rivet 10 is shown. The punch riveting apparatus 10 has a frame 60, which is preferably in the form of a C-frame or C-bracket, on which the individual components are usually arranged in a punch riveting apparatus in order to be able to assume the desired position relative to one another. About the frame 60, the punch rivet 10, for example, on an arm as in FIG. 1 be shown attached.

The punch riveting apparatus 10 has a punch (or sonotrode) 15, by way of example with a round cross section. The punch 15 is radially surrounded by a (sleeve-shaped) hold-down 16 and arranged movable relative to this in the longitudinal direction. The hold-down is fastened by means of a spring on the punch 15. Together, the punch 15 and the hold-down 16 form a joining tool 70. Furthermore, the punch 15 is coupled to a drive 50, which serves to apply a force F required to press the rivet 20 into the two components 11, 12. The drive 50 can be controlled, for example, by means of the computing unit 80. Also, the hold-down 16 is adapted to press against the surface of the die 15 facing member 11 with a hold-down force.

On the stamp 15 and the hold-down 16 opposite side of the two components 11, 12, a counter-holder in the form of a die 18 is arranged. The punch 15 and the die 18 are arranged in the vertical direction, as well as the hold-16, movable and movable relative to each other. The hold-down 16 and the die 18 serve to clamp or compress the two components 11, 12 between the hold-down 16 and the die 18 during processing by the punch 15.

The rivet 20, here by way of example a half-tubular rivet, preferably consists of a material which is harder than the materials of the two components 11, 12, at least in the region of a rivet shank. The component 11 facing away from the flat top of the rivet is arranged in operative connection with the punch 15, which rests flat against the top of the rivet 20.

The punch 15 is connected to a (mechanical) vibration converter 30, which can be excited via a vibration generator 32, in particular an ultrasonic generator, for generating vibrations. In particular, ultrasonic vibrations with an amplitude (distance between the maximum positive and negative amplitude of a vibration) between 10 .mu.m and 110 .mu.m (corresponding to an amplitude of 5 .mu.m to 55 .mu.m) and a frequency between 15 kHz and 35 kHz or possibly higher generated , These vibrations are coupled by the oscillation converter 30 via a booster 31 and the punch 15 in the rivet 20.

The drive 50 may be, for example, a drive with ball, roller or planetary screw drive or the like, which is suitable for pressing a force F of the rivet 20 in the components 11, 12 apply. On the drive 50, the booster 31 and above the vibration converter 32 and the joining tool 70 are mounted by means of a holding device 35. Together, the drive 50, the booster 31, the vibration converter 30 and the joining tool 70 form a setting unit 71.

Furthermore, the sound measuring device 81, for example a microphone, is arranged on the frame 60 of the punch riveting device 10. By means of the sound measuring device 81, a sound pressure or a sound pressure level (both variables can be converted into each other) can now be detected. A source of sound is here in particular the setting unit 71 or the area in which the rivet 20 rests on the component 11 into consideration. In this respect, a small distance from the source of the sound is selected by the arrangement of the sound-measuring device 81 shown. It is understood, however, that the sound measuring device can also be positioned or arranged otherwise.

In the present case, the sound measuring device 81 is additionally equipped with a radio module, for example for Bluetooth or WLAN, via which it can communicate with the arithmetic and logic unit 80, which likewise has a radio module. In addition, the sound measuring device 81 can, for example, have a battery for energy supply, which can be charged, in particular, by means of the mentioned energy harvesting.

In FIG. 3 is a curve of a sound pressure level, as it can occur in a method according to the invention in a preferred embodiment shown. For this purpose, the sound pressure level L _{p is} plotted as a characteristic of the sound pressure over the time t.

As can be seen from the graph, the sound pressure level increases with the start of an operating phase Δt, in which the vibrator is used to inject vibrations. Accordingly, the sound pressure level decreases again with the end of this operating phase .DELTA.t.

While the sound pressure level during the operating phase .DELTA.t is now higher than before and after, but still usually remains below a limit L _max , it may, for example, due to a functional restriction in a component of Punch riveting or a defect in a component or the rivet, it happens that the sound pressure level exceeds the limit L _max .

In such a case, for example, the power provided by the vibrator can now be reduced. Alternatively, the operation of the punch riveting apparatus can be terminated. In this way, the work safety can be maintained. However, it is also conceivable that, alternatively or additionally, a warning message is issued in order to warn people in the vicinity of the punch riveting device so that they can move away from the punch riveting device, for example.

It is also conceivable to use two or more different limit values which, if exceeded, take different measures, that is to say for example at a first limit value the warning message and only at a second limit value the termination of the operation of the punch riveting device.

It should be noted that the course of the sound pressure level L _p , in order to take appropriate action in the event of exceeding the limit, need not be recorded. Nonetheless, this can be helpful in order to be able to analyze the process later, if necessary.

In FIG. 4 is a curve of a sound pressure, as it can occur in a method according to the invention in a further preferred embodiment shown. For this purpose, the sound pressure p is plotted as a characteristic of the sound pressure value over a position x. The position x can designate the position of the punch relative to a reference position, for example a fixed point on the frame, when the rivet is pressed in.

Here, it can be seen from the course of the sound pressure p that, with increasing distance, it initially increases, then decreases again. It should be noted that only an exemplary course for explaining the present invention is shown here.

On the basis of the course of the sound pressure now any function restrictions or other problems, as they were mentioned, can be detected, since the course of the sound pressure then deviates from a desired course. Here are, for example a shoring of the correct rivet or rivet type, wear on one or more components (eg on punch or sonotrode, anvil, hold-down or drive), batch-dependent component variations or changes in the system structure, especially in insulation elements or the like in question. It is also conceivable to derive maintenance measures that are necessary due to such functional restrictions or changes.

It is conceivable in this context, for example, the use of a so-called. Envelope technique. For this purpose, two different upper boundary courses G ₁₁ and G ₁₂ as well as two lower limit courses G ₂₁ and G ₂₂ are shown by way of example, in the case of which they are exceeded or undershot, for example, a function restriction can be recognized. It is also conceivable, for example, to use the so-called window technique, in which one or more process-relevant windows, shown here by way of example with window 401, can be defined, within which limit values to be observed can be set and monitored.

Claims (13)

1. Method for monitoring a self-piercing riveting device (10) which is used to connect at least two components (11, 12) by means of a rivet (20) and in which, during at least one operating phase (Δt), at least one component (11, 12, 15, 18, 20) involved when pressing the rivet (20) into the at least two components (11, 12) is set vibrating by means of a vibration generator (32) as it is pressed in,
   characterized in that during the at least one operating phase (Δt), at least temporarily within a predetermined local distance range from the self-piercing riveting device (10), at least one variable (p, L_p) that is characteristic of a sound pressure is determined.
2. Method according to Claim 1, wherein the variable that is characteristic of a sound pressure comprises a sound pressure (p) and/or a sound pressure level (L_p), in particular in air in each case.
3. Method according to Claim 1 or 2, wherein when the variable (p, L_p) that is characteristic of the sound pressure exceeds a predetermined limiting value (L_max), a warning message is output and/or operation of the self-piercing riveting device (10) is changed, in particular terminated.
4. Method according to one of the preceding claims, wherein a time profile of the at least one variable (p, L_p) that is characteristic of the sound pressure and/or a profile of the at least one variable (p, L_p) that is characteristic of the sound pressure in relation to a position (x) of a component used to press in the rivet (20) is determined and in particular also recorded.
5. Method according to Claim 4, wherein the profile of the at least one variable (p, L_p) that is characteristic of the sound pressure is used for a quality assessment of an associated self-piercing riveting operation and/or a connection of the at least two components (11, 12) that is produced in the self-piercing riveting operation.
6. Method according to Claim 4 or 5, wherein the profile of the at least one variable (p, L_p) that is characteristic of the sound pressure is used to check a functionality of the self-piercing riveting device (10) or at least one component of the.
7. Method according to one of the preceding claims, wherein the at least one variable (p, L_p) that is characteristic of the sound pressure is determined by using a sound measuring apparatus (81), which is arranged on the self-piercing riveting device (10), in particular on a frame (60) or a setting unit (71) of the self-piercing riveting device (10) .
8. Method according to Claim 7, wherein the at least one characteristic variable (p, L_p) that is characteristic of the sound pressure and is detected by the sound measuring apparatus (81) is transmitted by cable or wirelessly to an evaluation unit (80).
9. Method according to Claim 7 or 8, wherein the sound measuring apparatus (81) is at least partly supplied with energy for operation by means of energy harvesting.
10. Method according to one of the preceding claims, wherein the vibration generator (32) used is a sound generator, in particular an ultrasound generator.
11. Method according to one of the preceding claims, wherein the at least one component that is involved in pressing in the rivet (20) and which is set vibrating comprises the rivet (20) and/or a punch (15) and/or an anvil (18) and/or at least one of the at least two components (11, 12).
12. Manufacturing apparatus (100) having a self-piercing riveting device (10), which is used to connect at least two components (11, 12) by means of a rivet (20) and in which, during at least one operating phase (Δt), at least one component (11, 12, 15, 18, 20) involved when pressing the rivet (20) into the at least two components (11, 12) can be set vibrating by means of a vibration generator (32) as it is pressed in,
    characterized by an assembly for monitoring the self-piercing riveting device (10), comprising a sound measuring apparatus (81) which is set up to detect at least one variable (p, L_p) that is characteristic of a sound pressure within a predetermined local distance range of the self-piercing riveting device (10), and
    an evaluation unit (80) for the detected variable (p, L_p) that is characteristic of a sound pressure.
13. Manufacturing apparatus (100) according to Claim 12, comprising means which are suitable to carry out a method according to one of Claims 2 to 10.

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