EP1533055B1 - Riveting device and method - Google Patents

Abstract

The device has a punch (9) and a corresponding rivet set (15) arranged on opposite sides of a support (2). The rivet set contacts with sheet irons (21, 22) before punching, by displacement of the support in an approach phase. The rivet set is mounted to be movable on the support between an extended position of detecting squeezing of the sheet irons, and a stow position, for punching the sheet irons. An independent claim is also included for a method of controlling a riveting device.

Description

The present invention relates to a riveting device, more particularly a riveting device comprising a punch and an imprint disposed on a movable support, see for example the document US-A-4955119.

It is possible to use sheet metal for fastening between them, and in particular for fastening metal sheets of a motor vehicle, a method of fastening by riveting in which sheets are brought into contact, an imprint is presented on one side of the plates to assemble, and a punch comes to apply a force on the sheets next to the impression, so as to deform the sheets to obtain a fixing point.

One can provide a riveting assembly comprising a support, or "head", provided with a print and a corresponding punch. The movable head is moved at different points to make fixing points for the assembly of the sheets.

However, the positioning of the plates to be fixed can be carried out with a certain tolerance. When the riveting head is moved by the robot to bring the impression into contact with a sheet to be assembled, if the sheet is not exactly in the reference position, the punching or riveting footprint may apply some effort on sheet metal, and some deformation of the sheet may result. If the deformation is important, this deformation of the sheet can remain permanently. Such deformation may be visible, for example on the painting of the sheet metal of a motor vehicle, which affects the external appreciation of the quality of the vehicle. Such deformation may subsequently cause assembly defects of inserts on the sheet, such as opening of a motor vehicle.

The present invention relates to an improved riveting device, and in particular such a device for assembling sheets avoiding the introduction of permanent deformation.

The invention also relates to a riveting device for positioning the support despite positioning defects of the elements to be assembled.

The invention further relates to a riveting device that can be obtained simply from a pre-existing device and can be obtained with a low manufacturing cost.

Such a riveting device comprises a punch and a corresponding recess arranged facing a support, the impression being intended to be brought into contact with an element to be assembled before the action of the punch, by moving the support in a phase of approach, the cavity being movably mounted on the support between a docking detection position and a stop position, provided for the punching action.

The footprint mounted on the support makes it possible, during the displacement of the support, for the footprint to come into contact with the element to be assembled, and for the support to be able to move relative to the element to be assembled (for example to rivet) without introducing a constraint in the element to be assembled. Thus, when the impression comes into contact with the element to be assembled, the impression moves from the extended position to the retracted position. This displacement makes it possible to detect the docking. The support is moved until the impression is in the stop position in which it is adapted to cooperate with the punch.

Preferably, the cavity is movable along an axis of movement of the support in the approach phase.

In one embodiment, it is expected that a displacement displacement of the cavity is substantially equal to a minimum stopping distance of the support moving at a determined approach speed. Thus, once the contact of the cavity with the element to be assembled detected, it commands a stop of the support, and taking into account the inertia of stop support, the latter will be permanently stopped when the footprint is substantially in stop position.

If the stopping distance of the support is slightly greater than the stroke of the footprint, this is not a problem insofar as low stresses are induced in the element to be assembled by positioning the footprint.

In one embodiment, it is possible to provide a displacement travel of the cavity substantially greater than a distance minimum stop of the support moving at a given approach speed. In this case, it will be possible, after detecting the contact between the impression and the element to be riveted, to control a gradual slowing down of the support on approach until the impression comes to the stop position.

In one embodiment, the device comprises an impression displacement sensor relative to the support, and a support displacement control module able to control the displacement parameters of the support as a function of a measurement signal provided by the sensor. The displacement sensor may be a sensor indicating whether the cavity is in the extended position or not to detect the docking or a displacement sensor to know the position of the impression between the output position and the retracted position, or its speed and its acceleration relative to the support.

In one embodiment, the impression is biased in the output position by an elastic member. Thus, when the fingerprint is not in contact with the element to be riveted, and is well in the output position so as to allow the detection of the contact sufficiently early to allow a stop command of the support.

In one embodiment, the support is mounted at the end of an articulated arm of a punching robot.

The invention also relates to a method of controlling a riveting device comprising a support bearing a punch and a corresponding corresponding footprint, the footprint being mounted on the support with the possibility of movement between a bogie detection out position. and a position in abutment for punching, in which the support is moved at a determined approach speed to bring the impression into contact with an element to be assembled, the docking is detected by a displacement of the impression relative to the support , and it controls a stop of the displacement of the support.

In an implementation mode, it controls a net stop of the support so that the inertia stop the support causes additional movement of the support until the cavity returns substantially in the stop position.

In one embodiment, it controls a progressive stop of the support until the cavity returns substantially in the stop position.

The present invention and its advantages will be better understood on studying the detailed description of an embodiment taken by way of non-limiting example and illustrated by Figures 1 to 5 attached showing a riveting device according to an aspect of the invention. invention in different positions during the realization of a riveting point.

In FIG. 1, a riveting device referenced 1 as a whole comprises a support 2 of general shape at C and comprising an upper branch 3, a lower branch 4, said upper 3 and lower 4 branches being connected by a central portion 5. The riveting device comprises a punch assembly 6 fixed to the free end of the upper branch 3 opposite to the central portion 5, and a cavity assembly or rivet 7 disposed at the free end of the lower branch 4 opposite to the central portion 5.

The punch assembly 6 comprises a casing 8 in which a punch 9 may be slidable comprising a rod 10 and a punching head 11, the punch 9 being able to move towards the set of cutter bars 7 on leaving or returning from the casing 8 To control a displacement of the punch 9 and to apply a punching force, an electric actuator or a piston / cylinder type actuator may be provided in the casing 8, not shown in the figures for reasons of simplification of the drawings, and which may be fed by a hydraulic pipe 12 opening into the casing 8 on the side opposite the punch 9.

The set of rivet 7 comprises a base 13 fixed to the end of the lower arm 4, the base 13 being provided with a blind or stepped hole 14 arranged in alignment with the punch 9 of the punch assembly 6. A rivet 15 comprises a rod 16 and an impression head 17. The rod 16 of the rivet 15 is arranged to slide axially in the blind or shoulder hole 14 so that the rivet 15 can move between a retracted position. in abutment (Figures 3, 4), in which the head 17 abuts on the base 13, and an exit position of docking detection (Figures 1, 2 and 5). The rivet 15 is located facing the punch 9 so that the rivet head 17 has a concavity cavity oriented towards the punch 9 and substantially in register with the punch head 9 to allow the deformation of elements of the punch. type sheet disposed between the rivet 15 and the punch 9. A spring or elastic member 18 is disposed in the blind hole or shouldered 14 between the bottom of the hole or shoulder 14 and the free end of the rod 16 of the rivet 15. spring 18 urges the rivet 15 in the output position. One can provide a stop, not shown in the drawing, to prevent a complete output of the rivet 15. The rivet 15 can move between the output position determined by said stop and the retracted position in which the rivet head 17 comes into 13. The stroke of the rivet is the distance between the head 17 of rivet 15 in the extended position and the base 13. The rivet assembly 7 further comprises a position sensor 19 able to detect the position of the rod. 16 of the rivet 15 in the blind or shoulder hole 14.

The riveting device 1 further comprises a control module 20 connected by a connection to the position sensor 19. The control module 20 comprises, in known manner, memory means and a microprocessor able to implement a computer program stored on the memory means and allowing the control of the riveting device 1, and in particular the control of a not shown articulated robot and intended to move the support 2.

As shown in Figure 1, the punch 9 is in the retracted position, and the rivet 15 is in the extended position. The support 2 is in a reference position to which it is brought beforehand. In this position, the punch 9 and the rivet 15 are located on either side of two elements to be assembled, in the form of a first and a second sheet 21, 22 arranged flat on one on the other.

Once the support has been brought to the reference position, the support 2 is moved, during an approach phase, in the direction indicated by the arrow F1, and which is aligned with the punching direction, that is to say, the direction of movement of the punch 9, and alignment of the punch 9 with the rivet 15.

Figures 2 to 5 are described later retaining the references used for Figure 1.

In FIG. 2, the support 2 has moved in the direction indicated by the arrow F1 until the ram head 17 comes into contact with a lower face 23 of the second plate 22 oriented towards the assembly. 7. If the support 2 continues slightly its movement, the rivet 15, which is retained by the elements to be assembled 22, 21, moves relative to the base 13 of the support 2. The rivet 15 enters the blind hole or shouldered 14 as indicated by the arrow F2. At the moment when the rivet 15 begins to move relative to the base 13, this displacement can be detected by the position sensor 19 and transmitted to the control module 20. In this case, the control module 20 commands a stop of the support 2.

Nevertheless, taking into account the inertia of the support 2, the support 2 continues to move relative to the elements to be assembled 21 and 22, the rivet 15 continuing to enter the base 13 as indicated by the arrow F2.

In Figure 3, which corresponds to the next step, the support 2 is immobilized. The rivet 15 is returned to its abutment position, in which the rivet head 17 bears by its larger diameter zone directly on the base 13. The rivet 17 is also in contact with the lower face 23 of the second element. assemble 22.

In FIG. 4, the output of the punch 9 has been controlled so that the punch head 11 has moved downwards until it comes into contact with the elements to be assembled 21, 22 to locally deform the latter by driving into the impression formed by the head of rivet 17.

The rivet head 17 having come into abutment directly on the base 13, the positioning of the rivet head 17 is safe and play-free relative to the position of the punch head 11 so that the assembly can be controlled satisfactorily. to get a fixing point having satisfactory strength and resistance characteristics.

Then, as shown in FIG. 5, the piston 9 is raised as illustrated by the arrow F4, then the support 2 is lowered as illustrated by the arrow F5, the base 13 of the support 2 moving away from the elements to be assembled 21, 22. The rivet 15, biased into the output position by the spring 18, (Figure 1) back to its docking detection output position so that it is ready for the next riveting operation.

An embodiment of a riveting method has been described in which the stopping of the support 2 is brutally controlled, the inertia of stopping the support 2 causing an additional displacement of the support 2 until the base 13 of the rivet assembly 7 comes into direct contact with the rivet head 17 to ensure a satisfactory maintenance of the rivet 15 during punching.

To do this, it is understood that the stroke of the notch allowed between the bog detection output position and the retracted position must be substantially equal to or less than the distance necessary to stop the support 2 when the latter moves at a specified approach speed. Of course, in the case where the stopping distance of the movable support 2 is greater than the stroke of the rivet 15, the additional displacement must be sufficiently reduced to prevent the introduction of permanent deformations in the elements to be assembled, beyond a punching deformation zone.

Of course, it will be possible to adapt the approach speed of the support 2 as a function of the jet stroke 15 available. Nevertheless, it should be taken into account that it is preferable to reduce a punching time to reduce the time required for the formation of the different attachment points between the elements to be assembled.

In another embodiment, it is possible to control a progressive stop of the support 2, in a controlled manner, via the control module 20, so as to cause, after detection of the docking of the rivet head 17 on the lower face 23 of the element to be assembled 22, an additional displacement of the support 2 until the rivet 15 is returned to the stop position.

To do this, the progressive stop can be controlled in a predetermined manner depending on the stroke of the rivet 15 and the determined approach speed of the support 2. It can be provided that the position sensor 19 used to know the position of the rivet 1 5 throughout its movement, and that the control module 20 allows to control the position of the support 2 with a control loop taking into account the position information of the rivet 15.

The term "riveting" may include the following methods, for which the invention may be applied interchangeably: clinching, self-punch riveting, punching. Similarly, the term "punching" can be replaced by "assembly", according to the method considered.

Thanks to the invention, a riveting device is obtained which makes it possible to bring an impression or rivet into the punching position, that is to say in contact with elements to be assembled, in a precise manner, and without inducing deformations in the elements to be assembled beyond a zone of deformation of the point of attachment. The riveting device can be obtained easily, from pre-existing devices, and with a low manufacturing cost.

Claims (10)

1. A riveting device comprising a punch (9) and a corresponding die (15) disposed facing one another on a support (2), the die (15) being adapted to be brought into contact with at least one member to be assembled (21, 22) before the action of the punch (9) by displacement of the support (2) in an approach phase, characterised in that the die (15) is mounted to move on the support (2) between an outward docking detection position and a retracted abutment position provided for the punching action.
2. A device as claimed in claim 1, characterised in that the die may move on the support (2) along an axis of displacement of the support (2) in the approach phase.
3. A device as claimed in any one of claims 1 or 2, characterised in that a displacement stroke of the die (15) is substantially equal to a minimum stopping distance of the support (2) being displaced at a predetermined approach speed.
4. A device as claimed in any one of claims 1 or 2, characterised in that a displacement stroke of the die (15) is substantially lower than a minimum stopping distance of the support (2) being displaced at a predetermined approach speed.
5. A device as claimed in any one of claims 1 to 4, characterised in that it comprises a sensor (19) of the position of the die (15) in relation to the support (2), and a module (20) controlling the displacement of the support (2) and adapted to control the displacement parameters of the support as a function of a measurement signal provided by the sensor (19).
6. A device as claimed in any one of the preceding claims, characterised in that the die (15) is urged into the outward position by a resilient member (18).
7. A device as claimed in any one of the preceding claims, characterised in that the support (2) is mounted at the end of an articulated arm of a punching robot.
8. A control method for a riveting device comprising a support (2) bearing a punch (9) and a corresponding die (15) disposed to face it, the die (15) being mounted on the support (2) such that it may be displaced between an outward detection position and a retracted abutment position for punching, characterised in that the support (2) is displaced at a predetermined approach speed in order to bring the die (15) into contact with a member to be assembled (21, 22), docking being detected by a displacement of the die (15) relative to the support, and the displacement of the support (2) being caused to stop.
9. A method as claimed in claim 8, characterised in that the support (2) is caused to stop sharply so that the inertia of the support (2) causes a supplementary displacement of the support (2) until the die (15) comes substantially into the abutment position.
10. A method as claimed in claim 8, characterised in that the support (2) is caused to stop progressively until the die comes substantially into the abutment position.

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