DE102014220771B4 - Method and device for producing an electrically conductive crimp connection between a conductor and a contact element - Google Patents

Abstract

Method (V) for producing an electrically conductive crimp connection between a conductor (1) and a contact element (2), wherein the conductor (1) is cooled relative to the contact element (2) and / or the contact element (2) is opposite the conductor (1) is heated to bring the contact element (2) and conductor (1) to different temperatures, and the conductor (1) and the contact element (2) with at least 50 K different temperatures by a joining device (120) are crimped together.

Description

The invention relates to a method and a device for producing an electrically conductive press connection between a conductor and a contact element, and to an arrangement comprising a conductor and a contact element, which are connected to one another in an electrically conductive manner by a press connection having a press fit.

Press connections between a conductor and a contact element can be found in many areas. Especially with conductors with a small cross-section and / or high mechanical stresses, it often happens that the electrical connection between the conductor and the contact element deteriorates over time. In order to provide a solution in which these problems occur less frequently, the conductor during assembly has a different temperature than the contact element. This causes the warmer of the two components to contract in the assembled state and / or expands the colder, so that when balancing the temperature differences between the two, a mechanical pressure that compresses the two builds up. A corresponding arrangement is characterized in that the conductor and / or the contact element are contracted with respect to their state during assembly in the press fit and / or expanded. A corresponding device comprises a joining device, with which the contact element is joined to the conductor, upstream device for temperature control, so that the contact element in the joining device has a different temperature than the conductor.

From the DE 10 2009 033 767 A1 For example, a method is known in which a connection element is thermally shrunk onto a stimulation electrode. The DE 441 377 A shows a method of making connections of lead or tie wires or cables, cable alarms, pipes, rods, etc., by shrinkage-based press devices. It shows a contact holder, which holds a cylindrical socket contact due to thermal shrinkage effect. From the post-published DE 10 2014 006 244 A1 For example, a method is known in which a stranded conductor is first crimped with a connection element and then welded. The DE 10 2011 089 206 A1 shows DE 10 2007 055 040 A1 a method in which a conductor and a contact are first crimped, then the conductor is heated to partially melt it, and finally a re-crimping between the conductor and the contact takes place.

The object of the invention is to provide a solution in which the connection is improved.

This is achieved by a method for producing an electrically conductive crimp connection between a conductor and a contact element, wherein the conductor is cooled relative to the contact element and / or the contact element is heated relative to the conductor to bring the contact element and conductor to different temperatures, and the Ladder and the contact element with at least 50 K different temperatures are crimped together by a joining device. Furthermore, this is achieved by a device for producing an electrically conductive crimp connection between a conductor and a contact element, wherein the device comprises a device for temperature control for cooling the conductor and / or for heating the contact element to at least 50 K different temperatures and a joining device for Crimping of the contact element and conductor has.

The solution according to the invention can be improved by the following advantageous developments and refinements. The individual features are each independent of each other and can be combined with each other.

A first component, which encloses or surrounds a second component in the assembled state, may have a higher temperature during assembly than the second component. The enclosed second component then has a correspondingly lower temperature during assembly. During and after assembly, a temperature compensation takes place. As a result, an interference fit is produced, in which the second component is pressed in the first component. In particular, a contact element which at least partially surrounds a conductor in the assembled state can have a higher temperature than the conductor.

The conductor and / or the contact element can be given a predetermined temperature in a step for temperature control. A step for temperature control may be separate and independent of other steps.

The higher of the two temperatures may in particular be above a maximum permitted operating temperature of the assembled arrangement. This ensures that the effect of the compression achieved by the thermal expansion is not lost during operation of the arrangement. In particular, the higher temperature may be at least 50 Kelvin, preferably more than 100 Kelvin above the maximum permitted operating temperature. Accordingly, the lower of the two temperatures may be lower than the lowest permitted operating temperature, in particular 50 Kelvin, preferably 100 Kelvin below this minimum operating temperature.

The higher of the two temperatures is preferably not higher than a temperature which leads to changes in the material, for example to softening or to phase or microstructural transformations, since these may adversely affect the effect achieved by the invention. Similarly, the lower temperature should be above such conversion points.

An arrangement produced according to the invention can be recognized, for example, by the fact that the metal has discolorations, for example bluish discoloration. Furthermore, a plastic insulation may be fused near the joint. Under the microscope, microstructure changes induced by the step for temperature control can be discernible.

In order to additionally achieve a better grip, the higher temperature may in particular be close to a softening temperature of the respective material, so that the material deforms slightly plastically. Cold weld density can also be increased by using higher temperatures.

In an advantageous embodiment, both components, i. both the conductor and the contact element are heated, wherein when joining the conductor has a different temperature than the contact element. By heating, for example, the materials can be softened, so that in addition to the interference fit generated by the temperature difference, a simple deformability is achieved. Alternatively, both components can also be cooled, with different temperatures prevailing in the two components during assembly.

The temperature difference between conductor and contact element is at least 50 Kelvin, preferably at least 100 Kelvin. The greater the difference, the stronger the additional pressure effect. The best value can be determined as a function of the thermal expansion coefficients of the materials.

The assembly is done by crimping. This represents a particularly simple and cost-effective connection method.

The conductor can be wire-shaped. It can be part of a cable. It can consist of several strands to achieve a simple deformability. Alternatively, the conductor may be configured as a single conductor.

The contact element may be configured as a crimping element or crimping sleeve. In addition to a section for plastic deformation, in particular for crimping with the conductor, it may also have other sections, in particular a contact section for contacting an external element. The external element may be about a mating contact element. The contact portion may be a male portion for mating connection with the external member. The contact element and / or the conductor may be part of a connector, in particular a plug. The connector may have other elements, such as further contact elements and / or conductors or a housing.

The contact element may be sleeve-shaped. It can partially or completely enclose the conductor in the assembled state. Tunnels or channels may be formed in which the conductor is accommodated. This can be a particularly efficient way of connecting. The sleeve can only be open at the front and back and closed at the sides. Alternatively, the sleeve may be laterally open.

In order to keep the effect achieved by the different temperatures as high as possible, the conductor and the contact element should be joined together very quickly. This will minimize the temperature balance between the two. Preferably, the assembly does not take longer than one second, preferably less than 0.5 seconds. Depending on the size, heat capacity and heat transfer rate, this value may also deviate upwards or downwards. In order to be able to achieve such speeds, it is advantageous if the joining takes place automatically, for example by machine.

In an advantageous embodiment, the joining together and the step of temperature control are partially performed simultaneously. For example, one of the two elements can be further heated or cooled, while plastic deformation has already partially begun. This can save time. Alternatively, the temperature setting can already be completed when the joining takes place. Such a procedure can be easier to implement.

In an advantageous embodiment, the contact element is heated. This can be done in different ways. For example, the contact element may have a thermally conductive contact with a hot element, so that heat is transferred to the contact element. The element can be solid. The contact element may also be in contact with a hot liquid, such as an oil. It can be immersed in an oil bath. In another embodiment, it may be heated by means of a hot gas. When There are further possibilities, for example, a resistance heating, ie that a current is passed through the contact element, so that the contact element heats up. A current flow in the contact element can also be generated contactlessly by a magnetic field, which in turn leads to a current flow and thus to a heating in the contact element by means of induction. Alternatively or additionally, radiation, for example laser radiation, can be absorbed by the contact element in order to increase the temperature.

In order to allow the heating of the contact element, the means for temperature control may comprise a heater with a receptacle for the contact element.

In addition or as an alternative to heating the contact element, the conductor can be cooled. This can be done for example by contact with a cold solid element. Even contact with a cold liquid, for example immersion in a cold liquid such as liquid nitrogen, can be used for cooling. Further, the conductor may be cooled by contact with a cool gas or draft. In particular, the conductors may also have been stored in a cold environment prior to assembly, for example in a refrigerator.

In order to allow cooling, the means for temperature control may comprise a cooling device with a receptacle for the conductor.

In the following, the invention will be explained in more detail by way of example with reference to advantageous embodiments and further developments with reference to the drawings. The features mentioned are each independent of each other and can be combined with each other, depending on how this is necessary in the application.

• 1 eine schematische Perspektivansicht des Zusammenfügens des Leiters mit dem Kontaktelement;
• 2 einen schematischen Querschnitt durch den Leiter, das Kontaktelement und die Vorrichtung während des Zusammenfügens;
• 3A eine schematische Darstellung eines Verfahrens bzw. einer Vorrichtung;
• 3B eine schematische Darstellung einer weiteren Ausführungsform des Verfahrens bzw. der Vorrichtung;
• 4A-F Darstellungen einer simulierten Druckverteilung ohne und mit thermischem Unterschied beim Zusammenfügen;
• 5A-F weitere Darstellungen von simulierten Druckverteilungen ohne und mit Temperaturunterschied beim Zusammenfügen.

Show it:

• 1 a schematic perspective view of the assembly of the conductor with the contact element;
• 2 a schematic cross section through the conductor, the contact element and the device during assembly;
• 3A a schematic representation of a method or a device;
• 3B a schematic representation of another embodiment of the method or the device;
• 4A-F Representations of a simulated pressure distribution without and with thermal difference during assembly;
• 5A-F Further illustrations of simulated pressure distributions without and with temperature difference during assembly.

In the 1 and 2 is the putting together of a leader 1 with a contact element 2 shown. Outside the connection area is the conductor 1 doing so in a cable 3 , the outside still an insulation 4 having. The leader 1 consists preferably of several individual conductors in the form of strands. This allows a slight deformability. The contact element 2 is designed as crimp or crimp sleeve. It has, in addition to a section for plastic deformation, in particular for crimping with the conductor, other sections, in particular a contact section for contacting an external element. The contact element 2 and / or the leader 1 can be used later in a connector, in particular a plug. The connector may have other elements, such as other contact elements 2 and / or ladder 1 or have a housing.

Before this deformation step, the conductor 1 by stripping the insulation 4 exposed and then in an approximately U- or V-shaped receptacle of the contact element 2 inserted. When joining, ie deforming, wing-like legs 5 of the contact element 2 bent inward, leaving the thighs 5 touch and the ladder 1 enclose. This is the contact element 2 with the conductor 1 together on an anvil 6 applied and then by the process of a stamp 7 along an actuation direction A deformed. This is usually done automatically and at high speed. The Stamp 7 exerts a high force. This will be the leader 1 and the contact element 2 also at least partially cold-welded together. Furthermore, the plastically deformed contact element exerts 2 on the ladder 1 a compressive force, ie the conductor 1 is pressed in the contact element.

To the compressive power F and to increase the cold-weld density, before that in the 1 and 2 shown joining step in which the head 1 with the contact element 2 is joined, a temperature difference between the conductor 1 and the contact element 2 produced. For example, the leader became 1 cooled and / or the contact element 2 heated. This causes the contact element 2 tries to contract after joining together or the leader 1 tries to expand. This in turn leads to a higher compressive force F so that the resulting arrangement 8th comprising the leader 1 and that the leader 1 enclosing contact element 2 , has a lower contact resistance and in particular a higher long-term stability. When the contact element 2 This can also cause it to deform more easily, which in turn can provide a better bond.

The heating of the contact element 2 can be done by various contacting or non-contact methods, such as by contact with a hot solid, a hot liquid, a hot gas, an induced or directly applied current flow or by the absorption of radiation, in particular laser radiation.

Cooling the conductor 1 can also be done by various methods, for example by contact with a cold solid, a cold liquid or a cold gas.

The preferred maximum and minimum temperatures are determined by the material properties. For example, certain phase transition or softening temperatures should not be undershot or exceeded. The temperatures used should be well outside the desired operating temperature range of the device 8th Otherwise, the effect according to the invention can otherwise be lost during operation. The difference between the two temperatures can be calculated based on the thermal expansion coefficients of the different materials depending on the desired effect. A temperature difference of 200 Kelvin has led to good results in tests with copper and aluminum.

An arrangement produced by the method according to the invention 8th comprising a conductor 1 with a contact element 2 , which are electrically conductively connected to one another by a press-fit having a press fit, characterized in that the conductor in the press fit 1 and / or the contact element 2 contracted and / or expanded compared to their state during assembly. In an arrangement according to the invention, the press fit is based at least partially on thermal expansion or contraction. This of course applies to an arrangement 8th in a state where it is ready for further processing or installation, ie in a state in which a thermal equilibrium exists between the conductor 1 and the contact element 2 has set. The contact element 2 is designed here sleeve-shaped. It surrounds the ladder 1 and press him in. An arrangement produced according to the invention 8th For example, it can be recognized by having discolorations on the metal caused by a heating step, so-called tarnishing. Structural changes can also have been produced by the heating and / or the cooling and can be seen approximately in a cross section. Also, specific heating or cooling methods can leave characteristic traces. For example, heating with a laser can cause typical changes to the surface or just below the surface.

In the 3A and 3B are methods according to the invention V shown schematically. Arrows indicate the production flow P shown. It can be seen that a joining step 20 a step towards temperature control 10 is upstream. In 3A is the step to temperature 10 completely before the joining step 20 , In 3B the two overlap at least partially. For example, a step for temperature control 10 , such as a warming, not yet complete, if already the joining step 20 For example, a deformation of the contact element 2 starts.

The diagrams of FIGS. 3A and 3B may also be schematic diagrams of a device according to the invention 100 be interpreted. The device 100 includes a joining device 120 and one of the joining device 120 upstream device for temperature control 110 , The thermal treatment device 110 In particular, a cooling device with a receptacle for the conductor 1 and / or a heating device with a receptacle for the contact element 2 include. The device for temperature control 110 can become parts of the device 100 with the joining device 120 share. For example, a holding device or a receptacle can be shared. The step to temperature 10 in the thermal device for temperature control 110 causes at least at the beginning of the joining step 20 in the joining device 120 a temperature difference between the conductor 1 and the contact element 2 consists. During the subsequent cooling, additional contact pressure is generated due to the thermal equalization between the two elements and the connection is thereby reinforced. To keep the effect as high as possible, the joining step should be done 20 as quickly as possible to avoid thermal compensation before the final assembly. With the usual line cross-sections of a few millimeters, the joining step takes less than one second, in particular less than 0.5 seconds. A typical cycle time is about 0.2 seconds for the joining step 20 ,

In the 4A to 4F and 5A to 5F are simulation results of various variants of arrangements comprising a conductor and a contact element (not shown). The figures arranged on the left ( 4A . 4C . 4E . 5A . 5C and 5E ) are simulations of an arrangement that has not been thermally treated. The figures arranged on the right ( 4B . 4D . 4F . 5B . 5D and 5F ) show simulations that initially show a temperature difference between the conductor 1 and the contact element 2 duration. The dark areas show the contact pressure. The darker the surface, the higher the contact pressure. In the 4A . 4B . 5A and 5B a connection was simulated in which the leader 1 and the contact element 2 consist of copper. In the 4C . 4D . 5C and 5D An aluminum conductor in a copper crimp barrel was simulated as a contact element. In the 4E . 4F . 5E and 5F was again simulated a compound of a copper conductor with a copper contact element, the two were additionally joined by bonding. The in the 5A to 5F simulations shown differ from those in the 4A to 4F shown by the fact that more pressure was exerted when crimping in other places. In all cases, it can be seen that the thermal treatment is increased to an increase in the number of areas in which a contact force is applied. Such compounds are therefore more stable.

LIST OF REFERENCE NUMBERS

1

ladder

2

contact element

3

electric wire

4

insulation

5

leg

6

anvil

7

stamp

8th

arrangement

10

Step to temperature

20

joining step

100

contraption

110

Device for temperature control

120

joining device

A

actuation direction

F

compressive power

V

method

P

production flow

Claims (11)

Method (V) for producing an electrically conductive crimp connection between a conductor (1) and a contact element (2), wherein the conductor (1) is cooled relative to the contact element (2) and / or the contact element (2) is opposite the conductor (1) is heated to bring the contact element (2) and conductor (1) to different temperatures, and the conductor (1) and the contact element (2) with at least 50 K different temperatures by a joining device (120) are crimped together. Method (V) according to Claim 1 , characterized in that the method comprises a step of temperature (10), and the contact element (2) during assembly has a higher temperature than the conductor (1). Method (V) according to one of Claims 1 or 2 , characterized in that the contact element (2) has a section for plastic deformation. Method (V) according to one of Claims 1 to 3 , characterized in that the contact element (2) is sleeve-shaped. Method (V) according to one of Claims 1 to 4 , characterized in that the assembly and the step of temperature control (10) are performed partially simultaneously. Method (V) according to one of Claims 1 to 5 , characterized in that the contact element (2) is heated. Method (V) according to one of Claims 1 to 6 , characterized in that the conductor (1) is cooled. Device (100) for producing an electrically conductive crimp connection between a conductor (1) and a contact element (2), wherein the device (100) has a device for temperature regulation (110) for cooling the conductor (1) and / or for heating the contact element (2) and a joining device (120) for crimping the contact element (2) and conductor (1) up, wherein the means for temperature (110) the conductor (1) and the contact element (2) to at least 50 Kelvin different Can set temperatures. Device (100) according to Claim 8 , characterized in that the contact element (2) in the joining device (120) has a higher temperature than the conductor (1). Device (100) according to one of Claims 8 or 9 , characterized in that the means for temperature control (110) comprises a cooling device with a receptacle for the conductor (1). Device (100) according to one of Claims 8 to 10 , characterized in that the means for temperature control (110) a Heating device comprising a receptacle for the contact element (2).

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