EP2985093B1 - Blind riveting apparatus and method for setting a blind rivet - Google Patents

Description

The invention relates to a Blindnietsetzgerät with the features of the preamble of claim 1.

Furthermore, the invention relates to a method for setting a blind rivet with the features of the preamble of claim 7.

Such Blindnietsetzgerät and such a method are of the generic type EP 2 719 482 A1 known.

Another Blindnietsetzgerät is for example off DE 41 26 602 C2 known. The electric motor is formed here reversible.

EP 0 572 819 A1 shows a method for determining the pull-off force of the mandrel of a blind rivet and an associated Blindnietsetzgerät, wherein in a compressed air line, a pressure gauge is arranged, with which the pressure required for the operation of the tension mechanism is measured.

Out WO 2013/180769 A1 It is known to stop a pulling mechanism in a blind rivet fastener by regenerative braking.

EP 0 953 390 A2 shows another Nietsetzgerät with an electrically operated drive motor, which has a motor shaft for driving a gear for translating the rotational movement of the motor shaft in a linear motion constant translation riveting the Nietsetzgeräts. In order to reduce the power consumption of this Nietsetzgeräts, a flywheel is provided, which is detachably connected via a coupling with the motor shaft. The drive device pulls a rivet mandrel in a pulling direction. From a predetermined tensile force or a predetermined path of the traction device breaks off the rivet mandrel. The engine can now be stopped. In this case, either a determination of the maximum tensile force can take place or it can simply be done switching off the drive motor after a predetermined path of the pulling device.

When setting a blind rivet, the mandrel of the blind rivet is inserted into the pull mechanism of the blind rivet setting tool. The pulling mechanism is for this purpose in a Nietaufnahmeposition in which it is open so far that the rivet mandrel can be introduced. If the blind rivet has then been inserted into the material to be joined, the operator can operate the operating device. In many cases, the operating device is designed as a pressure switch. The setting process is then started by pressing the pressure switch. The pulling mechanism is moved out of the rivet receiving position in the pulling direction. As a result, the shank of the blind rivet is deformed on the "blind" side of the joining material and forms a closing head there. When the pull mechanism is moved further, the mandrel eventually breaks. The operator then releases the pressure switch. The engine stops and returns the pulling mechanism to the rivet receiving position. Depending on the reaction speed of the operator, a more or less long follow-up time arises after the mandrel break or break.

In some cases, the operator has to set a large number of blind rivets in the same or similar manner. In this case, a habituation effect sets in after a relatively short time. The operator no longer waits for the audible break of the breaker, but releases the pressure switch in time for feeling. In this case, it often happens that the pressure switch is released too early and the mandrel is not yet demolished. This has the consequence that the rivet setting process must be repeated after the return. This costs time and energy, which is disadvantageous especially in battery-operated Blindnietsetzgeräten.

The invention is based on the object to optimize the setting process of a blind rivet in terms of speed and energy consumption.

This object is achieved in a Blindnietsetzgerät of the aforementioned type with the features of claim 1.

In such a Blindnietsetzgerät therefore the engine is operated only as long as required. Once the mandrel is torn off, further operation of the engine to move the pulling mechanism in the pulling direction is no longer necessary. The necessary detection of the corresponding state is carried out automatically by the demolition detection device, d. H. the corresponding information no longer needs to be obtained and processed by the operator. Since the human reaction time is omitted here, a certain time savings can be observed. Also eliminates the risk that the operator interrupts the setting process too early and therefore the setting process must be repeated. Again, this would unnecessarily cost energy and time.

Preferably, the controller brakes the engine with energy recovery. This is particularly advantageous in battery-operated Blindnietsetzgeräten because you not only saves time, but the existing in the traction mechanism and engine kinetic energy can be converted back into electrical energy.

It is also an advantage if the control device reverses the motor when the Dornabrisssignals occurs and the pull mechanism moves counter to the pulling direction. Thus, the pulling mechanism is again moved in the direction of the rivet receiving position, so that also for this movement practically no time is lost.

In a first preferred embodiment, the control device moves the pulling mechanism into the rivet receiving position. In the rivet receiving position, the pulling mechanism is opened and the torn-off mandrel may fall out. As the movement into the rivet receiving position begins immediately after the mandrel has been torn off, basically the shortest possible cycle time for the blind rivet setting process is achieved.

In a second preferred embodiment, the control means moves the pulling mechanism to a position outside the rivet receiving position. When the pulling mechanism is moved to the rivet receiving position, it is opened so that the pulling mandrel may fall out of the blind rivet setting device. This can lead to problems when a rivet case is present, in which rivets must be down. In this case, the falling mandrel may lead to problems in terms of safety at work, risk of short circuit in electrical assemblies, loose rivet mandrels in the component, etc. On the other hand, if you stop the pulling mechanism before it reaches the rivet receiving position, then the mandrel will remain in the riveting tool. The Blindnietsetzgerät can then be moved to a position in which a controlled disposal of the mandrel is possible. For example, if the blind rivet setting tool is provided with a mandrel receptacle at its rear end, then the blind rivet setting tool can be directed obliquely upward and the reel mechanism moved into the rivet receiving position by re-operation of the operating device so that the mandrel may fall back into the mandrel receptacle.

It is provided that the demolition detection device comprises a current monitoring device which continuously determines a current supplied to the motor and generates the Dornabrisssignal when the current after reaching a

Maximum value decreases at least by a predetermined percentage of the maximum value. When the mandrel is moved by the pulling mechanism, the force required to move the mandrel and thus the torque of the motor necessary to generate the force increases. This is due to the fact that the closing head of the rivet sleeve is formed by the movement of the mandrel. If the closing head is formed and further movement of the mandrel is practically no longer possible, the force increases so far that the mandrel tears off. As soon as the mandrel has been torn off, the force drops to a minimum value in a very short period of time and thus also the torque to be generated by the engine and with it the current absorbed by the engine. This drop in current can be relatively easily and reliably monitored and detected. For some setting operations, there are intermediate maximums of power consumption, for example, when the mandrel drowns in the rivet. However, it is possible to prevent erroneous detection of the thorn being disrupted by selecting the predetermined percentage of the maximum value as appropriate.

The predetermined percentage is 30%. You can also choose the predetermined percentage larger, such as 40%, 50%, 60%, 70% or 80%. This reliable detection of a mandrel breakage is possible.

Preferably, the operating device sends at least two different actuation signals to the control device as a function of different types of actuation. Thus, the operator may, for example, determined whether the pulling mechanism should be moved to the mandrel breakage to the Nietaufnahmeposition or whether it should be stopped shortly before the Nietaufnahmeposition, ie immediately before the impact of the chuck jaws of the pulling mechanism on the mouthpiece to a falling out of the mandrel to prevent. This is done to shorten the subsequent process time. The different types of actuation, for example, be designed so that in a first type of actuation the operating device is briefly actuated, for example, a pressure switch is pressed briefly and in a second actuation mode, the operating device is permanently actuated, so a pressure switch is kept pressed permanently.

The object is achieved in a method of the type mentioned above with the features of claim 7.

Thus, when the mandrel breaks off, the control device controls the motor so that the pulling mechanism is no longer moved. The pulling mechanism is thus only moved to Dorn Abrasion, so that unnecessary movements are avoided. This saves energy and time.

Preferably, when the Dornabrisssignals occurrence slows down the engine with energy recovery. Since the Dornabrisssignal reliably indicating the tearing of the mandrel, without the intervention of the operator is required, you can immediately after the mandrel break the stored energy in the engine and in the traction mechanism back into electrical energy, which is especially in battery or battery operated Blind rivet is advantageous.

Preferably, when the Dornabrisssignals occur, the direction of movement of the pulling mechanism is changed. This saves time again. Immediately after the demolition of the mandrel, the pulling mechanism is again moved in the direction of the rivet receiving position.

In a first embodiment, it is preferred that the pulling mechanism is moved into the rivet receiving position. Here then the mandrel can fall out of the pulling mechanism or be taken out.

In an alternative embodiment, it can be provided that the pulling mechanism is moved to a position immediately in front of the rivet receiving position. This prevents the mandrel from falling out of the blind riveting tool, which, as described above, can lead to problems.

To generate the Dornabrisssignals monitored the current consumption of the motor and generates the Dornabrisssignal when the current decreases after reaching a maximum value by at least a predetermined percentage of the maximum value. As explained above, the current consumption is a parameter that detects the torque generated by the engine. This torque is in turn a measure of the force with which the pulling mechanism acts on the mandrel. When the mandrel breaks off, then this force drops virtually suddenly to zero, which is due to a corresponding decrease in the current absorbed by the motor, for. B. at idle level, can easily recognize.

Preferably, the operating device is operable on at least two different types of actuation and sends in each actuation another signal to the control device. For example, if the operator briefly operates the operator, then upon the occurrence of the mandrel break signal, the controller reverses the motor and causes the pulling mechanism to be moved to the rivet receiving position. If, on the other hand, the operator permanently actuates the operating device, then this is a sign that the control device reverses the motor when the Dornabrisssignals occurs, but the pulling mechanism does not move into the rivet receiving position, but before the rivet receiving position stops, so that the mandrel can not fall out of the blind rivet set. The return then takes place, for example, after releasing the switch.

Fig. 1

eine stark schematisierte Ansicht von wesentlichen Funktionselementen eines Blindnietsetzgeräts, und

Fig. 2

einen stark schematisierten Verlauf der Kraft über den Weg beim Setzen eines Blindniets.

The invention will be described below with reference to a preferred embodiment in conjunction with the drawings. Herein show:

Fig. 1

a highly schematic view of essential functional elements of a Blindnietsetzgeräts, and

Fig. 2

a highly schematic course of the force over the way when setting a blind rivet.

The mechanical structure of a Blindnietsetzgeräts is in DE 41 26 602 C2 described. For this reason, only the functional elements that are essential for understanding the present invention will be explained below.

A Blindnietsetzgerät 1 has a housing not shown in detail, in which a pulling mechanism is arranged. The pulling mechanism has a jaw assembly 2 which is connected to a hollow threaded spindle 3. The threaded spindle 3 is in engagement with a transmission device 4. The transmission device 4 is connected via a transmission element 5 with a reversible electric motor 6.

The jaw assembly has a plurality of jaws 7, 8, which are closed in a setting operation of a blind rivet, not shown, so are pressed against each other with a certain force to seize a mandrel of the blind rivet and with a tensile force apply. This closed state of the jaw assembly 2 is shown by solid lines. However, the jaw assembly 2 can also be moved to a rivet receiving position shown in dashed lines, in which the jaws 7, 8 are opened and form a receiving opening 9 for the rivet mandrel.

From this rivet receiving position, the jaw assembly 2 can be moved in a pulling direction 10 shown by an arrow when the motor 6 acts on the jaw assembly 2 via the gear mechanism 4 and the threaded spindle 3.

The motor 6 is connected to a control device 11. The control device 11 receives electrical energy from a battery 12, which may also be designed as a rechargeable battery or accumulator. The control device 11 is also connected to an operating device 13, which has, for example, a pushbutton or pressure switch 14.

The control device 11 supplies the electric motor 6 with energy via a supply line 15 in the form of electrical current. In the supply line 15 (or at another position) in the control device 11, a current sensor 16 is arranged, which forms part of a demolition detection device 17. The current sensor 16 and the demolition detection device 17 are shown here as discrete elements. However, they can also be part of the control device 11.

Fig. 2 shows in a schematic form the course of the force F over the path s, travels the jaw assembly 2 in a setting operation of a blind rivet. Shown is a function 18. From the function 18 it follows that the force initially increases when setting a blind rivet. In many cases, this results in an intermediate maximum 19 when the mandrel engages in the rivet. After that, the power continues to increase, which points to it is attributable to the mandrel forming the closing head on the rivet sleeve. The force then continues to increase to a maximum of 20 and then collapses abruptly when the mandrel breaks. The demolition detector 17 now continuously monitors the current with the aid of the current sensor 16 (or otherwise) and detects the maximum 20 not only by detecting a maximum, but by checking that the current reaches the maximum value 20 decreases by a predetermined percentage of the maximum value. For example, this predetermined percentage may be 50%. The waste must, for example, take place in a section of the path s which is less than 1 mm, preferably less than 0.5 mm. This excludes with great certainty that the demolition recognition device 17 erroneously identifies the intermediate maximum 19 as maximum 20.

The force whose course is 18 in Fig. 2 is shown is generated via the transmission device 4 by a torque of the motor 6. The current consumption of the motor 6 correlates sufficiently with the torque, ie when the torque increases, then the current consumption of the motor 6 increases. This can be determined with sufficient accuracy, the maximum value 20 of the force F by a corresponding maximum of the absorbed current. In the same way you can see the in Fig. 2 recorded drop in power to a decrease or decrease in power consumption.

The detection of the mandrel breakaway reports the demolition detection device 17 directly to the control device 11. The control device 11 then terminates the drive of the clamping jaw arrangement 2 in the pulling direction. Advantageously, the control device 11 brakes the motor 6 with energy recovery. The energy gained is fed back into the battery 12 back. This has two advantages. On the one hand, there is energy recovered. On the other hand is lost by the braking of the motor 6 less time.

As soon as the engine 6 has reached its standstill, the control device 11 reverses the motor 6, so that the clamping jaw arrangement 2 is moved counter to the pulling direction 10. Alternatively, the engine 6 may simply stop.

This movement can extend as far as the rivet receiving position shown in dashed lines, in which the clamping jaws 7, 8 are moved apart, so that the torn-off rivet mandrel is released. This is then the shortest possible cycle time because the jaw assembly 2 are available again immediately after the termination of the setting process in a position in which they can take a new rivet mandrel.

In some situations, however, it is unfavorable to move the jaw assembly 2 into the rivet receiving position, for example, when the rivet setting device is held down during riveting. In this case, the torn off mandrel could fall out of the receiving opening 9 and damage the Fügegut or otherwise provide problems, such as cause a risk of short circuit in electrical assemblies or rattling noises when the rivet mandrel uncontrollably loose in a component.

In this case, the jaw assembly 2 is not moved to the rivet receiving position, but to the position shown in solid lines outside the rivet receiving position. This position is for example set so that the jaw assembly 2 only has to travel a short distance to open the jaws 7, 8.

In a manner not shown may be provided on the side facing away from the jaw assembly 2 end of the threaded spindle 3 is still a Dornaufnahmebehälter that receives the torn pull mandrels.

The different end positions of the jaw assembly 2 can now be selected by operating the pressure switch 14.

When the pressure switch 14 is actuated only briefly, the control device 11 starts the setting process and moves by means of the motor 6, the jaw assembly 2 in the pulling direction until the demolition of the mandrel, which is detected by reaching the maximum 20. Thereafter, the jaw assembly 2 is moved back against the pulling direction 10 back into the Nietaufnahmeposition and the jaws 7, 8 are opened.

If the pressure switch 14, however, pressed permanently, then the jaw assembly 2 is moved to the demolition or breakage of the mandrel and moved back into the position shortly before Nietaufnahmeposition. The jaw assembly 2 is not moved back to the rivet receiving position until the operator releases the pressure switch 14. Thus, the operator himself can determine when the mandrel is to be disposed of.

It is also possible to leave the clamping jaw arrangement 2 in the reached position after the tearing mandrel has been torn off and to let the resetting process of the clamping jaw arrangement 2 into the rivet receiving position start later overall. The return operation of the jaw assembly 2 can also be initiated here, for example, by releasing the pressure switch 14.

Of course, the different operating conditions can also be set in other ways, for example by providing an additional switch.

If no rivet is included in the Blindnietsetzgerät and the setting process is started anyway, no drop in the maximum current can take place. The jaw assembly 2 is then moved, for example, to the rear end position, corresponding to the maximum stroke, and remains after reaching the rear end position, without the jaw assembly 2 is moved back into the rivet receiving position. Only after releasing or re-pressing the switch 14, the return is started in the Nietaufnahmeposition.

The current sensor 16, as explained above, also be part of the control device 11. It can also be arranged between the control device 11 and the battery 12.

Claims (12)

1. Blind rivet setting device (1) having a housing, a tension mechanism (2, 3) in the housing, an electric motor (6) by means of which the tension mechanism (2, 3) can be displaced out of a rivet-receiving position in a pulling direction (10), a control device (11) for driving the motor (6) and an operating device (13) which is connected to the control device (11), the control device (11) comprising a tear-off detection device (17) which has a current monitoring device (16) continuously determining a current supplied to the motor (6) and generating a mandrel tear-off signal when a pulling mandrel is torn off, and the control device terminates the drive of the pulling mechanism (2, 3) in the pulling direction (10) when the mandrel tear-off signal occurs, characterized in that the tear-off detection device (17) generates the mandrel tear-off signal when the current drops by at least a predetermined percentage of the maximum value within a distance of 1 mm after reaching a maximum value (20), the predetermined percentage being 30%.
2. Blind rivet setting device according to claim 1, characterized in that the control means (11) brakes the motor (6) with energy recovery.
3. Blind rivet setting device according to Claim 2, characterized in that the control device (11) reverses the motor (6) and moves the pulling mechanism (2, 3) counter to the pulling direction (10) when the mandrel tear-off signal occurs.
4. Blind rivet setting device according to claim 3, characterised in that the control device (11) moves the tension mechanism (2, 3) into the rivet receiving position.
5. Blind rivet setting device according to claim 3, characterized in that the control device (11) moves the tension mechanism (2, 3) to a position outside the rivet receiving position, preferably to a position immediately before the tension mechanism (2, 3) opens.
6. Blind rivet setting device in accordance with one of claims 1 to 5, characterized in that the operating device (13) sends at least two different actuation signals to the control device (11) as a function of different types of actuation.
7. Method for setting a blind rivet, in which, when an operating device (13) is actuated, an electric motor (6) controlled by a control device (11) moves a pulling mechanism (2, 3) from a rivet-receiving position in a pulling direction (10), in which, when a pulling mandrel is torn off, a mandrel tear-off signal is automatically generated, on the basis of which signal the control device (11) stops actuation of the pulling mechanism (2), 3) in the pulling direction (10), the current consumption of the motor (6) being monitored in order to generate the mandrel tear-off signal, characterized in that the mandrel tear-off signal is generated when the current, after reaching a maximum value (20) within a distance of 1 mm, drops by at least a predetermined percentage of the maximum value, the predetermined percentage being 30%.
8. method according to claim 7, characterized in that the motor (6) is braked with energy recovery when the mandrel tear-off signal occurs.
9. Method according to claim 7 or 8, characterized in that the direction of movement of the pull mechanism (2, 3) is changed when the mandrel tear-off signal occurs.
10. Method according to claim 9, characterized in that the pulling mechanism (2, 3) is moved into the rivet-receiving position.
11. Method according to claim 9, characterized in that the pull mechanism (2, 3) is moved to a position outside the rivet receiving position, preferably to a position immediately before the pull mechanism (2, 3) opens.
12. Method according to any one of claims 7 to 11, characterized in that the control device (13) is operable in at least two different modes of operation and sends a different signal to the control device (11) in each mode of operation.

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