Electrical contact element comprising two crimp zones

Abstract

An electrical contact element (16) comprising a rigid conductor (6) and a contact sleeve (12) mounted on the rigid conductor (6), wherein the rigid conductor (6) and the contact sleeve (12) are crimped together, is designed to be particularly simple and space-saving and to meet the standards requirements even when, among other things, mechanical forces act on the rigid conductor (6). For this purpose, at least two crimp zones are provided, arranged one behind the other in the direction (x) of the electrical contact (16).

Description

[0001] The invention relates to an electrical contact element comprising a rigid conductor and a contact sleeve mounted on the rigid conductor, wherein the rigid conductor and the contact sleeve are crimped together. The invention further relates to a method for manufacturing such an electrical contact element and a crimping tool for crimping an electrical contact.

[0002] While it is desirable to connect rigid conductors directly to contact elements such as socket and plug contacts, this type of connection is critical because the rigid conductor can loosen, for example, due to temperature changes caused by current flowing through the rigid conductor, thus increasing the contact resistance, which can ultimately lead to a fire.

[0003] Until now, terminal blocks were frequently used to connect rigid conductors. A rigid conductor was inserted into the terminal block and clamped in place. These terminal blocks then function as plugs or sockets for further connections. However, a disadvantage of these terminal blocks is that they require more installation space due to the clamping body.

[0004] It is already known in principle that contact sleeves can be placed on the ends of rigid conductors. Crimping such contact sleeves onto the rigid conductors has also been attempted several times; however, such crimping has not yet been able to meet the safety requirements, in particular the crimping standard or other standards for electrical connections where tensile forces on the electrical connection or on the rigid conductor are to be expected. This is primarily because the electrical contact between the rigid conductor and the contact sleeve is located in the crimp area, and movement of the rigid conductor within the fixed contact sleeve, for example due to temperature differences when the rigid conductor is energized, leads to a gradual weakening of the crimp connection over time.Due to gaps forming in the crimp zone of the rigid conductor inside the contact sleeve, the electrical resistance between the rigid conductor and the contact sleeve increases, which not only impairs the electrical connection but can also lead to heat generation and subsequently to a fire over time.

[0005] Against this background, the object of the present invention is to provide an electrical contact element comprising a rigid conductor and a contact sleeve mounted on the rigid conductor, wherein the rigid conductor and the contact sleeve are crimped together, which is designed to be particularly simple and space-saving and which meets the standards requirements even when, among other things, mechanical forces act on the rigid conductor. Additionally, the object of the present invention is to provide a corresponding method for manufacturing such an electrical contact and a crimping tool for crimping such an electrical contact.

[0006] The problem is solved according to the invention by claims 1 and dependent claims 8 and 11. Advantageous embodiments are the subject of the dependent claims.

[0007] The invention is based on the consideration that, for example, the mechanical forces on the crimp zone, which also contains the electrical contact between the rigid conductor and the contact sleeve, must be reduced in order to meet safety requirements. In addition to the contact zone in the area of ​​the original crimp zone, at least a second zone is to be formed between the rigid conductor and the contact sleeve, which serves exclusively for strain relief. It was recognized that this strain relief zone can also be created by crimping, with this second crimp zone being arranged in the direction of the conductor's extension in front of the original, first crimp zone. This means that movements of the rigid conductor relative to the contact sleeve are initially absorbed by the second crimp zone, and the mechanical forces are reduced to the first crimp zone, where the actual electrical contact is located.Even though the two crimp zones initially appear technically identical, their sequential arrangement gives them distinct functions. The crimp zone located first in the direction of the rigid conductor serves solely to relieve strain and protect the downstream crimp zone from mechanical forces. This downstream crimp zone provides the electrical contact between the rigid conductor and the contact sleeve.

[0008] Even though multiple crimp zones are conceivable, and in certain applications an additional reduction of the mechanical forces acting on the crimp zone intended for contacting may be necessary through multiple strain relief zones in the form of several crimp zones, the use of only two crimp zones in total—one as a strain relief zone and one as a contact zone—is particularly advantageous. This is especially true considering that the manufacturing process for these crimp zones is simplified and the crimping tools can be produced more easily. Furthermore, this allows for a more compact and shorter contact sleeve.

[0009] For a particularly compact design and excellent strain relief in the contact zone, the second crimp zone, which serves for strain relief, is positioned very close to the first crimp zone. In an advantageous embodiment, the distance between the two crimp zones in the direction of the rigid conductor is less than 1 mm, preferably less than 0.5 mm, and in a particularly advantageous embodiment, approximately 0.4 mm.

[0010] In order to provide a sufficiently large contacting and strain relief area in the direction of extension, while also creating a potentially compact system, the crimp zones are approximately 1.6 mm long in a particularly advantageous design.

[0011] A contact sleeve made of a brass alloy, especially a lead-free brass alloy, is particularly advantageous for good electrical contact in the contact zone and a particularly stable connection in the strain relief zone. By using two or more crimp zones, it is now possible for the first time to use a lead-free CuZn42 alloy for the contact sleeve, which was not previously possible.

[0012] Especially for a compact electrical connection system made of rigid conductors, the contact sleeve is advantageously designed as a plug or socket contact. This makes it particularly easy to connect two rigid conductors by crimping a contact sleeve in the form of a plug contact onto one and a contact sleeve in the form of a matching socket contact onto the other.

[0013] To prevent the crimp zone for contacting the strain relief zone from being subjected to additional mechanical stress during crimping, the crimp zones are advantageously crimped simultaneously during the manufacturing process of the electrical contact. For this purpose, the crimping die pairs for the individual crimp zones are also rigidly connected to each other, for example, by welding or screwing them together.

[0014] For adequate electrical contact and strain relief, a crimping ratio of approximately 20-25% has proven particularly advantageous. This means that the cross-section of the contact sleeve or the rigid conductor is reduced by about 20-25% along the crimp axis. Also considering electrical contact and strain relief, a double B-shape for the crimping die pairs is particularly preferred. However, it is also conceivable that the crimp shapes for the individual crimping zones differ; for example, a diamond shape for one or both crimping die pairs is possible.

[0015] The advantages achieved with the invention consist in particular of the fact that, for the first time, it is possible to connect a rigid conductor to a contact sleeve by crimping, while also meeting the required safety standards. By using at least two pairs of crimping dies in succession, a more secure connection between the rigid conductor and the contact sleeve can be provided without additional work steps or connecting elements.

[0016] The invention is further described with reference to the exemplary embodiments shown in the drawings. These show: Fig. 1 two crimp dies arranged one behind the other, Fig. 2 Two pairs of crimping dies in perspective view, Fig. 3 two pairs of crimping dies with a rigid conductor in cross-section, Fig. 4 an electrical contact element with two crimp zones.

[0017] The illustrations in the figures are sometimes simplified and schematic. Different views of parts may be scaled differently. Identical reference numbers are used for identical or structurally equivalent parts.

[0018] In the exemplary embodiment according to the Fig. Figure 1 shows two crimping dies 1a, 1b. Each of these crimping dies 1a, 1b comprises a base body 2 and a die shape 4a, 4b formed on a free end of the base body 2. The base bodies 2 are rigidly connected to each other by means of fastening elements (not shown), but can alternatively also be welded together. Furthermore, the base bodies 2 include insert elements or recesses 8 for inserting and securing the crimping dies 1a, 1b in a tool for the machine production of the electrical contacts or in pliers for finishing at the point of use.

[0019] The die shapes 4a, 4b are arranged at the free end of the respective base body 2 and positioned relative to each other such that the distance between the two crimping zones or the two die shapes in the direction x is less than 1 mm, preferably less than 0.5 mm, and in a particularly advantageous embodiment in the range of approximately 0.4 mm. In the present embodiment, die shape 4a is arranged, by way of example, at the edge of the base body 2, while die shape 4b is arranged at a distance from the edge of the base body 2, namely by the distance required for the spacing between the two crimping zones. Each of the two die shapes 4a, 4b is designed as a B-shape. In principle, however, it is also possible for one or both of them to be designed as a diamond shape. It is also possible for different die shapes 4a, 4b to be used for machine crimping than for crimping on-site using pliers.The use of a B-shape is particularly advantageous for machine crimping, while the diamond shape could be used for crimping with pliers.

[0020] For crimping the electrical contacts, two crimping dies 1a, 1c and 1b, 1d always form a crimping die pair 10a, 10b. The two crimping dies 1a, 1c and 1b, 1d of a crimping die pair 10a, 10b are arranged such that the contact sleeve 12 to be crimped and the rigid conductor 6 to be crimped lie between the two crimping dies 1a, 1c and 1b, 1d or between the two die shapes 4a, 4c and 4b, 4d, and the crimping dies 1a, 1c and 1b, 1d can both or one relative to the other be moved along the pressure axis y. An embodiment of the invention with two interconnected crimping die pairs 10a, 10b is shown in Fig. Figure 2 shows that the two crimping dies 1c, 1d are essentially similar in design and connected to each other, as are the crimping dies 1a, 1b from the embodiment shown in Figure 2. Fig. 1. They differ only in that crimp dies 1a, 1b have a receiving area 14 extending in the direction x, into which the contact sleeve 12 and the rigid conductor 6 can be inserted. Although not shown, an alternative embodiment allows the receiving area 14 to be provided in crimp dies 1c, 1d, or alternatively, for each of the crimp dies 1a, 1b and 1c, 1d to have a receiving area 14, the depth of which is then reduced such that the receiving area 14 is formed jointly by all crimp dies 1a, 1b, 1c, 1d.

[0021] In Fig. Figure 3 shows a cross-sectional view of the crimping of an electrical contact 16 consisting of a contact sleeve 12 and a rigid conductor 6. The two pairs of crimping dies 10a, 10b, spaced apart along the x-direction of the electrical contact 16, are visible, each pair comprising a crimping die 1a, 1c or 1b, 1d. Each of these crimping dies 1a, 1b, 1c, 1d has a die shape 4a, 4b, 4c, 4d, which in this embodiment is designed as a B-shape. During the crimping process, i.e., when the crimping dies 1a and 1c or 1b and 1d are pushed towards each other along the pressure axis y, two double-B crimp zones 20a, 20b are formed in the electrical contact 16, arranged side by side and spaced apart from each other along the x-direction.

[0022] An electrical contact 16, manufactured according to the above-described method or by the above-described crimping tools, is in Fig.Figure 4 shows the contact sleeve 12 being placed on a free end of the rigid conductor 6 and crimped together using a crimping tool. The two crimp zones 20a, 20b, arranged one behind the other in the direction x, are clearly visible. Reference symbol list 1a, 1b, 1c, 1d Crimp dies 2 basic shapes 4a, 4b, 4c, 4d Stamp shape 6 rigid ladders 8 Insert elements or recesses 10a, 10b crimping die pairs 12 Contact sleeve 14 Recording area 16 electrical contact element 20a, 20b crimp zones x direction of extension y pressure axis

Claims

[1] Electrical contact element (16) comprising a rigid conductor (6) and a contact sleeve (12) placed on the rigid conductor (6), wherein the rigid conductor (6) and the contact sleeve (12) are crimped together, characterized by , that at least two crimp zones (20a, 20b) are present, arranged one behind the other in the extension direction (x) of the electrical contact (16). [2] Electrical contact element (16) according to claim 1, characterized by that there are exactly two crimp zones (20a, 20b). [3] Electrical contact element (16) according to claim 2, characterized by , that the two crimp zones (20a, 20b) are essentially identical. [4] Electrical contact element (16) according to one of claims 1 to 3, characterized by , that at least two adjacent crimp zones (20a, 20b) are arranged next to each other at a distance of less than 1 mm, preferably at a distance of less than 0.5 mm, in particular at a distance of about 0.4 mm. [5] Electrical contact element (16) according to any one of claims 1 to 4, characterized by , that the length of at least one crimp zone (20a, 20b) in the extension direction (x) of the electrical contact (16) is approximately 1.6 mm. [6] Electrical contact element (16) according to any one of claims 1 to 5, characterized by , that the contact sleeve (12) is made of a brass alloy, preferably a lead-free brass alloy. [7] Electrical contact (16) according to claim 6, characterized by , that the contact sleeve (12) is made of a CuZn42 alloy. [8] Electrical contact element (16) according to any one of claims 1 to 7, characterized by , that the contact sleeve (12) is designed as a plug or socket contact. [9] Method for producing an electrical contact (16) from a rigid conductor (6), wherein a contact sleeve (12) is pushed onto the rigid conductor (6) at its conductor end and the contact sleeve (12) is then crimped to the rigid conductor (6), characterized by that the crimping is carried out through at least two crimp zones (20a, 20b). [10] Method for producing an electrical contact (16) according to claim 9, characterized by that the at least two crimp zones (20a, 20b) are formed in one work step and essentially simultaneously. [11] Method for producing an electrical contact (16) according to one of claims 9 or 10, characterized by , that the crimp zones (20a, 20b) have a compression ratio of approximately 20-25%. [12] Crimping tool for crimping an electrical contact (16), characterized by, that at least two pairs of crimp dies (10a, 10b) are arranged one behind the other in the extension direction (x) of the electrical contact (16). [13] Crimping tool for crimping an electrical contact (16) according to claim 12, characterized by , that each pair of crimp dies (10a, 10b) has a double B shape. [14] Crimping tool for crimping an electrical contact (16) according to one of claims 12 or 13, characterized by , that the crimping die pairs (10a, 10b) are rigidly connected to each other.

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