EP3258550A1 - Device and method for crimping of fastener elements and crimped connection - Google Patents

Abstract

The present invention relates to a device (1) for crimping connecting elements (2). The device (1) comprises a machine frame (5), at least one punch, a drive arrangement, at least one anvil (17) and a working space (31). The punch (3) is preferably arranged movably in relation to the machine frame (5). The punch (3) contains at least one working surface (4) for deforming a connecting element (2). The drive arrangement for moving the punch (3) is connected to the punch. The anvil (17) is connected to the machine frame (5) and has a receiving surface (8) for the connecting element (2). The working space is located between the punch and the anvil and can be opened and closed by a relative movement between the punch and the anvil. The device has at least one sonotrode, by means of which the receiving surface (8) of the anvil (17) can be acted upon by ultrasound.

Description

The present invention relates to a device and a method for crimping fasteners and a crimp according to the preambles of the independent claims.

Crimping is a joining process in which a stripped cable is connected to a connector. By the connecting element, the stripped cable can then connect to other electrical or electronic components. When crimping a cable is inserted into the connecting element and the connecting element is usually plastically deformed. Due to the plastic deformation, the connecting element is pressed against the cable or the electrical conductors of the cable. In this case, the connecting element encloses a stripped, ie bare, line part (core crimp) and the line insulation (insulation crimp). The core crimp is used for the electrical connection, the insulation crimp of the strain relief and fixation of the insulation. By this connection, electrical energy can be transmitted from the cable to the connecting element and on.

Out DE 10 2013 219 150 A1 For example, a method for producing an electrically conductive connection between an electrical line and an electrically conductive component is known. In the document, a crimping element which partially encloses the individual conductors is deformed and then connected to a part of the individual conductor. In addition, the document proposes to connect a part of the individual conductors by an ultrasonic welding process by means of a sonotrode. The document shows a process with two process steps. In the first process step is crimped and in the second process step, a Ultraschallweissvorgang is performed with a second device.

DE 30 17 364 A1 discloses a method and apparatus for connecting a conductor to a tab. In the process, a crimping operation and an ultrasonic welding process are performed in a single operation. This happens because an upper die is designed as a sonotrode end of an ultrasonic welding device. As a result, the material is softened and reduces the necessary force when lowering the embossing punch (sonotrode). Consequently, the force needed to deform the crimp element can be reduced.

Another method for connecting a contact element to a cable is in DE 103 36 408 B4 disclosed. In the method, a contact element with a pair of crimp connection tabs is uniformly constricted radially inward. This compound is then welded by another tool with ultrasonic vibrations. Again, separate crimping and ultrasonic machines are used.

It is therefore the object of the invention to overcome the disadvantages of the prior art. In particular, a device is to be made available, which is simple in construction and easily generates permanent crimp connections.

Another object of the invention is to improve the strength of a crimped connection.

A further object of the invention is to improve the fatigue strength of a crimp connection and to improve a chemical resistance of the crimp connection. It is also an object of the invention to increase the electrical conductivity of a crimp connection.

These objects are achieved by the device defined in the independent claims, the method defined in the independent claims, the anvil defined in the independent claims and the crimped connection defined in the independent claims. Further embodiments emerge from the dependent claims.

A first aspect of the present invention relates to a device for crimping fasteners. Typically, the connectors are crimped with copper or aluminum strands. The apparatus typically comprises a machine frame, at least one punch, a drive assembly, at least one anvil and a working space. The stamp is preferably arranged movably in relation to the anvil and in particular to the machine frame. The stamp contains at least one working surface for deforming a connecting element. The drive order for moving the punch is connected to the punch. The anvil has a receiving surface for the connecting element and is preferably connected to the machine frame. The working space is located between the punch and the anvil and can be opened and closed by a relative movement between the punch and the anvil. The device has at least one sonotrode, by means of which the receiving surface of the anvil can be acted upon by ultrasound.

A machine frame is understood here to mean a frame on which machine parts can be fastened. Examples of machine frames are housings, frames or other devices, such as presses, which are suitable for supporting parts of the machine.

A stamp is a part that is suitable for deforming another part. The deformation can be done by the fact that the Stamp pressure on the part to be deformed exercises. The stamp is held, for example, in a crimping die receiving device, such as a moving part of a press.

A drive arrangement for moving the punch is preferably pneumatic, hydraulic or electric. The stamp preferably moves along a linear direction of movement. In this case, the drive arrangement may be suitable to drive a certain way or to exert a certain force or to introduce a certain energy. A drive arrangement for moving the stamp is for example a press, in particular an eccentric press.

As anvil, this is understood as the counterpart to the stamp. Between anvil and stamp the connecting element is deformed. In this case, the anvil is preferably connected to the machine frame.

A sonotrode is understood here to be an arrangement which is preferably designed to oscillate in a frequency of 15-50 kHz. The sonotrode can vibrate torsionally, linearly or longitudinally.

The inventive device has the advantage that the sonotrode is particularly easy to integrate into a device for crimping. There are only a few structural changes necessary to integrate the sonotrode in the device. Furthermore, by introducing ultrasound, an oxide layer at the edge of a conductor, onto which the connecting element is crimped, can be broken open. In particular, individual conductors of stranded conductors are connected to one another by the ultrasound. Another advantage is that less force over the punch must be applied. Another advantage is that crimp process monitoring is improved.

Another advantage is that can be crimped and ultrasonically welded simultaneously with only one device. Crimps, which are produced with such a device, have a special quality, since they are mechanically stronger and more electrically conductive.

In preferred embodiments, the device is suitable for crimping a plurality of strands with a connecting element. Particularly preferred connecting elements are double stops, in which two strands are connected to a connecting element. For double stops, two aluminum strands (aluminum / aluminum), two copper strands (copper / copper) or a mixture (copper / aluminum) can be connected to the connector. The double stops can be executed side by side and one above the other.

The device preferably has two receiving surfaces, a wire crimping region and an insulation crimping region. The areas may be part of a one-piece anvil, each part of one of two anvils. The anvils are vibrationally decoupled from each other. Each of the anvils has a receiving surface for crimping. At least one of the receiving surfaces, preferably only one, can be acted upon by ultrasound.

This can be crimped at each of the receiving surfaces. For example, a connector could be deformed with multiple crimping sections. Alternatively, several different elements could be crimped. Usually, a part of the connecting element is crimped to an insulation of a conductor and another part of the connecting element is on the electrical conductor crimped. In this case, preferably only the electrical conductor with the connecting element is ultrasonically welded. Therefore, preferably only the anvils for the electrically conductive crimp are subjected to ultrasound. Particularly preferably, the anvils are decoupled by a distance between each other in terms of vibration. Alternatively, the anvils can also be vibrationally decoupled by cushioning materials such as a foil lying between the anvils.

In an alternative embodiment, the device contains only a one-piece anvil. Particularly preferably, the single-storey anvil contains two receiving surfaces.

This is a particularly simple embodiment for a machine that combines ultrasonic welding and crimping in combination.

In a preferred embodiment, the at least one anvil is detachably connectable to the sonotrode. In a particularly preferred embodiment, the anvil is shrink-on the sonotrode. Alternatively, the anvil can be connected by means of a thread or a plug connection to the sonotrode.

Most preferably, each sonotrode is releasably connectable with one or more anvils. Alternatively, only individual sonotrodes with one or more anvils can be detachably connectable.

This makes the anvil interchangeable. If, for example, the receiving surface wears out, only the anvil needs to be replaced and the sonotrode can continue to be used. In a preferred alternative embodiment, the sonotrode at least partially forms the anvil.

In an alternative embodiment, the sonotrode is in contact with the anvil, but without being fixed to the anvil. In this embodiment, replacement of the anvils is particularly easy.

In this embodiment, the sonotrode forms the anvil. If the device contains more than one anvil, the sonotrode can form only single, multiple or all anvils.

This allows a simple design with few parts.

In a preferred embodiment, the receiving surface is subjected to torsional vibrations about an axis perpendicular to the receiving surface. Particularly preferably, the receiving surface is curved and acted upon with oscillations about an axis along a direction of movement of the punch.

Torsional ultrasonic welding has the advantage that no embrittlement of the connecting element arise. Furthermore, the ultrasonic energy can be introduced particularly efficiently.

Usually, in addition to the device for crimping other devices, for example, for processing or further transport. Torsional ultrasonic vibrators can be installed perpendicular to a transport direction of the connecting element. Therefore, torsional ultrasonic welding can be spatially more easily integrated, without the other devices must be changed.

In an alternative embodiment, the receiving surface can be acted upon by longitudinal oscillations along an axis parallel to the receiving surface. Preferably, the longitudinal vibrations oscillate along a longitudinal axis of the conductor or perpendicular to the longitudinal axis of the conductor.

Longitudinal vibrations can be used in particular if a torsional oscillator can not be integrated into the device, for example for reasons of space.

In a further alternative embodiment, the receiving surface can be subjected to longitudinal oscillations parallel to a direction of movement of the stamp.

In a preferred embodiment, at least the part of the anvil subjected to vibrations is decoupled from the machine frame and the anvil can not be moved relative to a machine frame during the process. Preferably, the anvil is not movable relative to the machine frame.

An example of a vibrationally decoupled storage of the anvil is a zero point bearing with flanges.

As a result, only the punch has to be moved during a crimping process. Consequently, the movement is easy to carry out, since the ultrasonic arrangement including the drive and sonotrode does not have to be moved. Another advantage is that the ultrasonic vibrations from the anvil are not transmitted to the machine frame.

Not to be moved here means that a vibration, in particular an ultrasonic vibration, is allowed, but no other translatory or rotary movements.

In a preferred embodiment, the work surface is curved such that a contact area between the punch and the anvil is minimized.

If the contact area is lower, less vibrations are transmitted from the anvil to the punch. As a result, the stamp can be kept more stable and is more resistant to the ultrasonic vibrations and therefore more durable.

Preferably, the frequency can be adapted to the duration of the closing process. For example, a high frequency can be used with temporally short closing movements. As a result, nevertheless a sufficient number of vibrations is introduced.

Particularly preferred vibrates the sonotrode with a frequency of greater than or equal to 20kHz.

During the crimping process force is applied over a short time (for example approx. 200ms). At high frequencies, ultrasound can be introduced more effectively. In a further particularly preferred embodiment, the sonotrode vibrates at 30 kHz or at 35 kHz.

The device can additionally be used for compacting a strand, in particular a copper or aluminum strand.

A further aspect of the present invention relates to a method for producing a connection between an electrical conductor, preferably a copper or aluminum conductor, and a connecting element. First, a connecting element is inserted into an open working space, which through an anvil and a movable punch is defined. One end of an electrical conductor is inserted into the connecting element. The working space is closed by the movable punch. In this case deform during the closing at least one working surface of the punch and at least one receiving surface of the anvil, the connecting element in particular plastically, so that a frictional contact between the electrical conductor and connecting element is formed. Ultrasound is introduced by means of a sonotrode into the receiving surface of the anvil during and / or after a crimping process.

Such a method has the advantage that the sonotrode does not have to be moved during crimping. Another advantage is that with only one processing step in a single device can be simultaneously crimped and ultrasonically welded.

The introduction of the ultrasound through the anvil allows a more efficient initiation of the ultrasonic vibrations, since the anvil during crimping over a larger area is continuously in contact with the connecting element. As a result, shorter process times than with separate ultrasonic welding and crimping can be achieved and / or more energy can be introduced into the connecting part.

A further advantage is that the vibrations can be introduced more directly into individual conductors of a cable.

In a preferred method, ultrasound is also introduced into the receiving surface by means of the sonotrode prior to the crimping process.
In a preferred method, the stamp is not subjected to ultrasound. This is a burden of the stamp reduced by ultrasound and wear on the stamp is reduced.

In a preferred method, the introduction of the ultrasound breaks up an oxide layer on the electrical conductor.

The breaking up of the oxide layer improves the electrical conduction between the connection element and the electrical conductor. In particular aluminum conductors have an outer oxide layer, which reduces the conductivity. Such a layer is broken up by ultrasonic vibrations.

In a preferred method, the movable punch has a first working surface and the anvil has a first receiving surface. When closing the working space, a first portion of a connecting element is connected to a preferably electrically conductive part of the electrical conductor through the first receiving surface and the first working surface. The movable die has a second working surface and the anvil has a second receiving surface. When closing the working space, a second portion of a connecting element is connected to the electrical conductor, preferably with an insulation of the conductor, through the second receiving surface and the second working surface.

As a result, a high electrical conductivity can be produced by a first crimp, while a second crimp ensures a stable mechanical connection.

In a preferred method, ultrasound is introduced into the first, preferably only the first, working surface.

As a result, lower amounts of energy must be applied in the ultrasonic welding and the energy can be used more efficiently.

In a preferred method, ultrasonic torsional vibrations are introduced into the connecting element.

Preferably, the ultrasound is at least, more preferably only, transferred at the time of maximum adhesion of the punch an ultrasonic pulse in the connecting element.

At the maximum adhesion, the ultrasound is transferred most effectively to the connector and / or the strand. It is also conceivable to initiate the ultrasound permanently, i. before, during and after the crimping.

The ultrasound can be introduced permanently or in pulses.

Another aspect of the invention relates to a crimp connection made by a method of making a connection between an electrical conductor according to any one of the claims.

Crimp connections, which are produced by such a method, have a special quality, since they are mechanically strong and more electrically conductive. In particular, individual conductors of stranded conductors are connected to one another by the ultrasound and an oxide layer is at least partially wiped. Furthermore, the individual strands are cold-welded by the introduced pressing force and the introduced ultrasound. The induced vibrations promote the process of connection, reducing the total force required and rubbing it at the same time possible oxide layers better than conventional crimping.

Another aspect of the present invention relates to an anvil for an ultrasonic crimping process. The anvil has a receiving surface for a connecting element and an interface. The anvil can be detachably connected to a sonotrode.

As a result, a sonotrode can be connected to an anvil for crimping and a connection element can be crimped with a tool and subjected to ultrasound. Furthermore, the anvil is interchangeable and can therefore be easily and inexpensively replaced when worn. Preferably, the anvil is shrunk. Alternatively, the anvil can be connected by means of a thread or a plug connection.

Figur 1:

eine perspektivische Ansicht einer Vorrichtung zum Crimpen.

Figur 2:

ein Querschnitt eines Stempels und eines Ambosses einer Vorrichtung zum Crimpen.

Figur 3:

eine perspektivische Detailansicht der Vorrichtung zum Crimpen.

Figur 4:

eine perspektivische Ansicht der Vorrichtung zum Crimpen.

Figur 5:

eine perspektivische Ansicht eines unteren Maschinenteils der Vorrichtung zum Crimpen.

Figur 6:

eine Seitenansicht der Vorrichtung zum Crimpen

On the basis of figures, which represent only embodiments, the invention will be explained in more detail below. They show schematically:

FIG. 1:

a perspective view of a device for crimping.

FIG. 2:

a cross section of a punch and an anvil of a device for crimping.

FIG. 3:

a detailed perspective view of the device for crimping.

FIG. 4:

a perspective view of the device for crimping.

FIG. 5:

a perspective view of a lower machine part of the device for crimping.

FIG. 6:

a side view of the device for crimping

The perspective view in FIG. 1 shows a device for crimping 1. In FIG. 1 the device 1 is shown in an open position. An upper machine part 26 (see FIG. 2 ) was moved upwards in the direction of 30.

In the FIG. 1 the lower machine part 25 of the device is shown. A plurality of connecting elements 2 is guided in the lower machine part 25. The connecting elements 2 are each connected to a carrier strip 9 for the connecting elements 2. Between the connecting element 2 and the carrier strip 9, a contact is provided. The connecting elements 2 themselves contain a first pair of crimping blades 10 for crimping around an electrical conductor (not shown) and a second pair of crimping blades 11 for a strain relief crimp around an insulation of the conductor. Furthermore, each connection element 2 contains a connection part 12 with which the conductor can then be connected to a connection. The carrier strip 9 transports the connecting elements 2 along a transport direction 21 into the device for crimping 1.

The device 1 includes a machine frame 5 through which all machine parts are connected. The fasteners are crimped at a lower tool 7 and a punch 3 (see FIG. 2 ). The tool 7 and the punch 3 are located at a holding surface 28 for the carrier strip 9 of the connecting elements 2 and a bearing surface 29 for the connecting part. Between these two surfaces is the tool 7 with two anvils 17, 18.

If a stamp 3 (see Fig. 2 ) moves on the tool 7, then the support surface 28 is pressed with the carrier strip 9 down. The contact between carrier strip 9 and connecting element 2 is cut through by a spring-mounted knife. As a result, the contact between the carrier strip 9 and the connecting element 2 is interrupted. After the crimping process, the punch 3 is removed from the tool 7 again and the conductor with the connecting element is removed from the working space 31. Subsequently, a new connecting element 2 is fed into the working space 31 by the carrier strip 9 of the connecting elements 9 being pushed in the direction 21.

FIG. 2 shows a cross section of a section of the device 1 in a plane which is formed by the transport direction of the connecting elements 21 and a vertical direction 30. In FIG. 2 a crimping process is illustrated in the first pair of crimp blades 10. Before the process, an electrical conductor is stripped at one end. As a result, individual conductors 23 of a stranded conductor are free. In the first step of the process, the connecting element 2 is inserted into a working space 31. The working space 31 is formed by the punch 3 and the anvil 7. The connecting element 2 is inserted through the carrier strip 9 in the working space 31. The free end of the stranded conductor is a Kuhle 32 (see Fig. 5 ) are inserted into the connecting element 2, so that the free individual conductors 23 are located between the first pair of crimping blades 10 and the insulation of the conductor lies between the second pair of crimping blades 11 (not shown). Then the punch 3 of the upper machine part 26 is moved in the direction of the tool 7. The punch 3 is driven by an eccentric press. The stamp 3 has a work surface 4. The work surface 4 deforms the connecting element 2. The work surface 4 shown produces a so-called B-crimp. Furthermore, the work surface 4 a Curvature 20 on which the first pair of Crimpflügel 10 slides and is deformed. Through the work surface 4, the Crimpflügel are first bent inwards and finally downwards. The deformation of the Crimpflügel is plastic. During deformation, the individual conductors 23 are pressed together by the crimping blades 10. In this case, the individual conductors 23 are pressed one against the other so that, if possible, there are no free spaces between the individual individual conductors 23. Further, the connecting element 2 is pressed by the pressure of the punch 3 against a receiving surface 8 of the anvil.

While the connecting element 2 is plastically deformed by the punch 3, ultrasound is simultaneously introduced into the connecting element 2 and into the individual conductors 23 via the receiving surface 8. The tool 7 oscillates about an axis 27 in a direction of vibration 22. The vibration is transmitted from the anvil 18 to the receiving surface 8 and from the receiving surface 8 in the connecting element 2 and the individual conductors 23. This oscillation in ultrasonic frequency generates friction between the individual conductors 23 and between the Crimflügeln 10 and the individual conductors 23. The friction causes a welding and breaks an oxide layer on the outside of the ladder. As a result, the individual conductors 23 are welded and an electrical resistance in the transition between individual conductors 23 to connection element 2 is reduced.

FIG. 3 shows a detailed view of the device 1 for crimping. In FIG. 3 the support surface 28, the support surface 29 and the receiving surface 8 can be seen in detail. The tool 7 includes a first anvil 17 for an insulation crimp and a second anvil 18 for the conductor crimp. The insulation crimp anvil 17 crimps the second pair of crimp blades 11. The crimp anvil 18 crimps the first pair of crimp blades 10. The punch 3 accordingly has two anvils 17, 18, with which the Crimpflügel 10, 11 are deformed.

FIG. 4 schematically shows an arrangement for generating ultrasonic torsional vibrations. The arrangement contains two ultrasonic converters 13. The ultrasonic converters 13 are connected to a torsional oscillator 14. The torsional oscillator 14 is a cylindrical body on whose lateral surface on opposite sides of the converter 13 are connected. The converter 13 swing in push-pull. As a result, a torsional movement about its own axis 27 of the converter is generated.

The torsional oscillator 14 is held by a zero point bearing with a flange 35. The flange 35 is shrunk onto the torsional oscillator at a node of the torsional vibration 14. The flange 35 holds the torsional oscillator 14 in which it rests on carriers 36. At the same time the flange 35 is pressed by clamps 37 from above onto the carrier 36.

Connected to the torsional oscillator is a transformation piece 24, which is designed according to the desired oscillation amplitude. To the transformation piece 24, a sonotrode 19 is connected, which forms the anvil 18 for crimping.

FIG. 5 shows a further schematic view of the device 1 for crimping. In FIG. 5 a conceivable height adjustment for the lower punch 18 is shown. By pressing, that is by turning the wheel 15, the anvil 17 is moved in the direction of the axis 27.

FIG. 6 shows a side view of the device 1 for crimping. In the device 1, the lower punches 17, 18 are separated by a gap 33 and do not touch. The gap is wider as the oscillation amplitude with which lower punch 18 oscillates. The lower punch 18 is also decoupled in terms of vibration from the machine frame 5 through a second gap 34. In addition, the lower punch is connected by the zero point bearing with flanges with the machine station (see Fig. 4 ).

Claims (15)

Device (1) for processing and in particular for crimping connecting elements (2), preferably with copper or aluminum strands, the device comprising: at least one punch (3) which contains at least one working surface (4) for deforming a connecting element (2), a drive arrangement (6) for moving the stamp, at least one anvil (17), the anvil having a receiving surface (8) for the connecting element, a working space (31) between the punch and the anvil, which can be opened and closed by a relative movement between punch and anvil, characterized in that the device has at least one sonotrode, by means of which at least the receiving surface (8) of the anvil (7) can be acted upon by ultrasound. Device according to claim 1, characterized in that the device comprises a single or at least two anvils (17,18), the anvils being vibrationally decoupled from one another and each of the anvils having a receiving surface for crimping, at least one, preferably only one, of the Recording surfaces can be acted upon by ultrasound. Device according to one of the preceding claims, characterized in that the at least one anvil with the sonotrode is detachably connectable, preferably, the anvil is aufschrumpfbar to the sonotrode. Device according to one of the preceding claims, characterized in that the sonotrode at least partially forms the anvil. Device according to one of the preceding claims, characterized in that the receiving surface with torsional vibrations about an axis perpendicular to the receiving surface or with longitudinal vibrations along an axis parallel or transverse to the receiving surface can be acted upon, the sonotrode in particular oscillates at a frequency greater than or equal to 20kHz. Device according to one of the preceding claims, characterized in that at least a part of the anvil is decoupled from a machine frame vibration moderately and the anvil relative to a machine frame during the process is not movable. Device according to one of the preceding claims, characterized in that the working surface is curved such that a contact surface between the punch and the anvil is minimized. Use of a device according to one of the preceding claims for compacting a strand, in particular a copper or aluminum strand. Method for producing a connection between an electrical conductor, preferably a copper or aluminum conductor, and a connecting element, preferably by means of a device according to one of claims 1 to 8, comprising the following steps: Inserting a connecting element into an open working space defined by an anvil and a movable punch, - Inserting one end of an electrical conductor in the connecting element - Closing of the working space by the movable punch - Wherein during closing at least one working surface of the punch and at least one receiving surface of the anvil deform the connecting element, so that a frictional contact between the electrical line and connecting element is formed, - Introducing ultrasound is preferably introduced permanently or in pulses, by means of a sonotrode into the receiving surface of the anvil during and / or after a crimping process, wherein preferably an oxide layer on the electrical conductor is broken by the introduction of ultrasound. A method according to claim 9, characterized in that when closing the working space, a first portion of a connecting element with a, preferably electrically conductive, part of the electrical line through the first receiving surface of the anvil and the first working surface of the punch is connected, and when closing the working space second portion of a connecting element is connected to the electrical line through a second receiving surface of the anvil or a receiving surface of a second anvil and a second working surface of the punch or a working surface of a second punch. A method according to claim 10, characterized in that ultrasound is introduced into the first, preferably only in the first, receiving surface. Method according to one of claims 9 to 11, characterized in that ultrasonic torsional vibrations are introduced into the connecting element. Method according to one of claims 9 to 12, characterized in that at least, preferably only, with maximum adhesion between the punch and connecting element, an ultrasonic pulse is transmitted into the connecting element. A crimp connection produced by a method according to any one of claims 9 to 13. Anvil for a method for producing a connection between an electrical conductor, preferably a copper or aluminum conductor, and a connecting element, preferably a method according to one of claims 9 to 13, wherein the anvil has a receiving surface for a connecting element, characterized in that the Anvil has an interface by means of which the anvil is releasably connectable to a sonotrode.

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