Method for crimping a female electrical terminal onto an electrical wire while preserving the integrity of its contact cage, and crimping tool for implementing such method

Abstract

A method of crimping a female electrical terminal (100) onto a multi-strand electrical wire (200) comprises compressing the crimping wings (131a, 131b) of the electrical terminal (100) to deform them for crimping and, providing that a transition part (120) of the electrical terminal (100) which joins the crimping zone (130) to the contact cage (110) of the electrical terminal (100) is simultaneously hold by a retaining flange (631a, 631b), so as to prevent said transition part (120) to widen laterally, while the crimping wings (131a,131b) are compressed for crimping. This prevents the contact cage (110) from opening by lateral spreading of opposing first and second folded portions thereof, away from a longitudinal seam zone (113), which could otherwise be indirectly caused by high pressure applied by the crimping tool on the crimping wings.

Description

BACKGROUND Technical Field

[0001] The invention generally relates to the field of electrical connections. In particular, the invention concerns a method of crimping a female electrical terminal onto an electrical wire while preserving integrity of its contact cage, as well as a crimping tool for implementing this method.

[0002] It finds non-limiting applications in the automotive industry, for example in automotive connector applications.Related Art

[0003] The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.

[0004] In connection techniques, one uses the coupling of male and female electrical terminals to make an electrical connection between wire segments or between a wire segment and an electrical or electronic device, for example. Male and / or female connector terminals are electrically joined, by welding, crimping or another technique, to a stripped end portion of an electrical wire. The present disclosure relates to the crimping of a female terminal onto a multi-strand electrical wire, i.e. an electrical wire whose conducting core comprises several conducting strands.

[0005] In automotive connections, electrical terminals are often made by stamping and shaping a sheet of copper or a copper alloy such as brass. More precisely, these terminals are manufactured by cutting and folding a thin, flat metal strip with a thickness ranging from 0.2 mm to several millimetres (mm). Due to the need for these terminals to have a good rigidity, the material used is not very ductile.

[0006] The connector manufacturer supplies individually preformed terminals bonded to a carrier strip (or supporting tape) wrapped in a reel with a separating band of non-abrasive material. These reels are fed into a crimping machine at the connector manufacturer's customer site, e.g. a wiring harness manufacturer.

[0007] Wires are also generally made of copper, or aluminium to reduce the weight of electrical wiring harnesses in electric vehicles in particular. An electrically conductive multi-strand core is sheathed with an outer sheath of insulating material, usually plastic.

[0008] An electrical connection between an electrical wire, in particular a multi-strand wire, and a metal terminal is known to be made by a crimping operation in which wings cut from the metal strip are bent around a stripped end portion of the electrical wire using a crimping tool of the punch-and-anvil type.

[0009] These preformed terminals comprise: a contact part, configured to be mechanically and electrically connected to a complementary counter-terminal; a rear part forming a force-absorbing or stress-release zone provided with open longer wings which are designed to be closed on the insulating sheath of the electrical wire; and, an intermediate part forming a crimping zone, between the front part and the rear part, provided with a semi-open barrel with open crimping wings which are designed to be crimped onto a stripped portion of an electrical wire to create an electrical contact between the terminal and the electrical wire.

[0010] In case of a female terminal, the front part is shaped as a contact cage configured to receive a mating contact blade of the male counter-terminal. This contact cage is extended rearwards by a transition zone between the front part and the crimping zone. This cage features a longitudinal seam, resulting from the formation of the cage by the folding of the cut metal strip.

[0011] The contact cage may contain at least one arcuate contact spring blade, fixedly arranged in electrical continuity with the inner walls of the cage, in order to improve contact with the contact blade of the connector's counter-terminal when the latter is inserted into the contact cage.

[0012] In order to enhance the electrical conduction in the area of the contact zones between an electrical wire and an electrical terminal, especially a multi-strand aluminium wire whose strands might be covered by an oxide layer, one tends to increase the level of compression of the wire in the crimping zone in order to break up the oxide layer upon crimping, and to prevent the reforming of this oxide layer after crimping. Another reason why the striking force applied during crimping might be increased, is when the contact terminal is used in combination with wire having a core with a cross-section larger than the one for which the terminal has originally been designed. The electrical wires used in certain specific applications have increased from a cross-section of around 2 to 3 mm 2< to a cross-section of around 6 mm 2< , due to the increased electrical power consumed in new generations of vehicles. But this increase in the level of compression during crimping raises a number of problems.

[0013] Among other things, when crimping is carried out the transition zone can widen laterally, and the contact cage can therefore open by around 1 mm in its rear part close to the transition zone, which can have an impact on the operational contact force. In particular, this can lead to a displacement of the spring blade from its standard position, with the possible consequence of a deterioration in the contact force between the contact cage and the mating contact blade when the male and female terminals are operatively connected.

[0014] The present invention aims to at least partially remedy the above-mentioned consequence.

[0015] Patent reference FR3033450A1 discloses a crimping tool of the stamp-anvil type for implementing a method of attaching an electrical terminal to a wire, said tool having two successive segments in the longitudinal direction of the electrical terminal, namely a first segment to compress wings of the electrical terminal in an area of a mechanical retention portion and a second segment to compress the wings in an area of an electrical conduction portion, wherein a height difference between the first and second segments is between 0.4 and 0.7 mm, or less, and between 0.5 and 0.6 mm in certain cases. Thanks to this arrangement (which may result for example from the geometry of a specifically designed crimping punch), the deformations of the terminal in the transition zone between the mechanical retention portion and the electrical conduction portion are limited and the terminal has no crack or tear.

[0016] Patent reference WO2009115860A1 discloses a method of crimping an electrical terminal onto a wire which comprises: providing an assembly comprising a wire and an electrical terminal; applying an initial crimping step, by folding an initial part of the crimping section over the stripped part of the wire; and applying a subsequent crimping step, by compressing another part of the crimping section over the stripped part of the wire. The second crimping step is carried out over a part of the wing surface that has undergone the first crimping step. This allows the mechanical behavior of the crimp to be modified in order to use the physical phenomenon of spring back in a favorable direction on a particular area of the terminal. It has been identified, indeed, that a spring back effect exists at the crimping wings, and even if the dimensional variations are only of the order of a few microns, this spring back effect can cause an intermittent loss of contact between the wire strands and the contact terminal.SUMMARY

[0017] The invention aims to remedy all or some of the disadvantages of the above identified prior art.

[0018] To address these needs, a first aspect of the proposed solution relates to a method of crimping a female electrical terminal onto a multi-strand electrical wire as defined by the features as claimed in claim 1. The method comprises: providing an assembly comprising: o an electrical wire locally extending along a longitudinal direction and having a stripped end portion comprising a plurality of electrically conductive strands, o an electrical female terminal comprising at least the following parts provided along a longitudinal direction: □ a proximal part, shaped as a contact cage configured to receive a mating contact blade of a male counter-terminal, said contact cage featuring a longitudinal seam zone between opposing first and second folded portions of the cage resulting from the formation of said cage by the folding of a cut metal strip; □ a distal part forming a crimping zone, shaped as a semi-open barrel with at least one pair of crimping wings configured to be crimped onto a stripped end portion of the electrical wire to create an electrical contact between the terminal and the electrical wire; and, □ a transition part, arranged between and configured to join the first longitudinal part and the second longitudinal part, a crimping segment with a semi-open barrel-shaped base configured to receive the electrical wire and having at least one pair of individual crimping wings each extending substantially vertically and having a connection end connected to the barrel and a free end opposed to the connection end, said crimping wings facing each other on either side of the barrel and having a determined length along the longitudinal direction, said stripped end portion of said electrical wire extending into said barrel between said crimping wings, said method further comprising: o compressing the crimping wings of the electrical terminal to deform them for crimping; and, o simultaneously holding the transition part of the electrical terminal retained between laterally spaced retaining jaws so as to prevent said transition part widening laterally while the crimping wings are compressed during the crimping.

[0019] A second aspect of the proposed solution relates to a female connector terminal according to claim 2, which can be used for implementing the method of crimping according to the first aspect. The crimping tool is of the stamp-anvil type, having a punch for crimping a female electrical terminal onto a multi-strand electrical wire, said terminal comprising at least the following parts provided along a longitudinal direction: a proximal part, shaped as a contact cage configured to receive a mating contact blade of a male counter-terminal, said contact cage featuring a longitudinal seam zone between opposing first and second folded portions of the cage resulting from the formation of said cage by the folding of a cut metal strip; a distal part forming a crimping zone, shaped as a semi-open barrel with at least one pair of crimping wings configured to be crimped onto a stripped end portion of the electrical wire to create an electrical contact between the terminal and the electrical wire; and, a transition part, arranged between and configured to join the first longitudinal part and the second longitudinal part, wherein the punch comprises at least one crimping gripper with a pair of laterally spaced crimping teeth and at least one retaining flange with at least one pair of laterally spaced retaining jaws, said retaining flange being adjacent to and ahead of said crimping gripper along the longitudinal direction, and wherein: the punch has a W-shape in cross-section at level of the crimping gripper, configured to compress and deform the crimping wings of the electrical contact terminal upon crimping; and, the retaining jaws of the retaining flange are configured to hold the transition part of the electrical terminal firmly gripped therebetween during crimping so as to prevent said transition part from widening laterally, while the crimping wings are compressed by the crimping gripper for crimping.

[0020] Thanks to these features, the proposed method of crimping and the proposed crimping tool make it possible to remedy, or at least significantly mitigate, technical problems such as those mentioned above, encountered with a method of crimping using a conventional crimping tool as per the prior art.

[0021] In particular, crimping of the terminal onto a wire with a larger wire cross-section, and / or crimping using a higher compression force can be achieved, without altering the integrity of the connection cage (or contact cage) and therefore without compromising the quality of electrical contact with the connector's counter-terminal.

[0022] Further embodiments of the proposed solution are defined in the dependent claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which: Figure 1 is a perspective view of a preformed female terminal of an electrical connector to which the teachings of the invention can be applied for crimping of said terminal onto a stripped electrical wire. Figure 2 is a top view of the female terminal of Figure 1. Figure 3 is a side view of the female terminal of Figure 1. Figure 4 is a longitudinal cross-sectional view of the female terminal of Figure 1, in section plane A-A as shown in Figure 2. Figure 5 is a partial perspective view of a crimping tool with a of the punch-anvil type, comprising a crimping punch according to the prior art. Figure 6A is a perspective view of a crimping punch according to embodiments, which can be used for carrying out the proposed method of crimping. Figure 6B is a front view of the crimping punch of Figure 6A. Figure 6C is a side cross-sectional view of the crimping punch in Figure 6A, in the median vertical section plane B-B as shown in this figure. Figure 7A is a partial perspective view of a crimping tool according to embodiments, with a female terminal positioned in said tool, ready for initiation of the crimping operation. Figure 7B is a partial perspective view similar to that of figure 7A, illustrating an intermediate stage in the crimping process. Figure 7C is a partial perspective view similar to those of Figures 7A and 7B, at the end of the crimping operation. DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] The following figures and description illustrate specific exemplary embodiments of the invention. It is therefore obvious that those skilled in the art will be able to devise various arrangements which, although not explicitly described or illustrated herein, embody the principles of the proposed solution and are included within the scope of the claims. In addition, all examples described herein are intended to facilitate understanding of the principles of the solution and should be construed as not being limited to the examples and provisions specifically disclosed. Accordingly, the scope of the claims is not limited to the specific embodiments or examples described below, but only by the features set forth in the claims and their equivalents.

[0025] In the figures of the accompanying drawings, like reference numerals refer to same or similar elements. In addition, unless specifically stated otherwise, the disclosures contained in the entire description can be applied analogously to the same parts with the same reference signs or the same component identifiers.

[0026] In the following description, functions or constructions well-known by the one skilled in the art are not described in detail since they would obscure the description in unnecessary detail.

[0027] There will be firstly described a female electrical terminal which is adapted for being crimped onto the stripped end portion of an electrical wire. In the example shown, the terminal is a female terminal of an unsealed APEX 2.8 ™< series automotive connector, available from Aptiv (formerly Delphi), which has been originally designed for use with a male terminal having a blade size of 2.8 mm.

[0028] For the purpose of the description which follows, there is defined a direct three-dimensional orthogonal reference system XYZ, where X- and Y-axes form a horizontal plane XY, and where the X- and Z-axis form a vertical plane XZ perpendicular to said horizontal plane XY. By way of convention, this reference system XYZ is tied to the female terminal.

[0029] The expression "three-dimensional space" (or 3D) characterizes the space surrounding the terminal, as perceived by a user's vision, in terms of width, depth and height. In mathematics, this notion corresponds to Euclidean geometry in space, according to which space is marked by three orthogonal axes, whereas a plane is made up of only two dimensions (2D) and is marked by only two of said three orthogonal axes. The three geometric dimensions thus are: length along the longitudinal X-axis, oriented by way of convention from the rear to the front; width along the transversal Y-axis; and, height along the vertical Z-axis, oriented by way of convention from the bottom to the top.

[0030] In addition, and unless explicitly stated otherwise, the spatially related terms and expressions in quotation marks below (and all derived terms, as well as semantically equivalent expressions) are used in the present disclosure according to the following convention: "rear" and "front", "behind" and "ahead", "backside" and "frontside", "backward" and "forward", and derivatives such as "in (the) front of", an "in the rear of" as well as associated verbs and derived nouns or expressions, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) in reference to the direction of the longitudinal axis X; "left", "right", "side" or "lateral", may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) with respect to the transversal axis Y as illustrated in the figures.; and, "bottom" and "top", "below" and "above", "under" and "over", the verbs "to decline" and "to rise" and any derivatives, synonyms or equivalents, as well as the terms "superior" and "inferior", as well as associated verbs and derived nouns or expressions, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) with respect to the vertical axis Z as illustrated in the figures, which is oriented from the bottom to the top on the figures of the drawings.

[0031] The above spatially relative terms and like terms and expressions are intended to encompass different orientations of the terminal in use or operation, in addition to the orientation depicted in the figures. The terminal 100 may be otherwise oriented (e.g. be rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0032] With particular reference to the different views in Figure 1 to Figure 4, the female electrical terminal 100 comprises, arranged in series along a longitudinal direction X, a distal end portion 110, a proximal end portion 130, and an intermediate portion 120 between the distal end portion 110 and the proximal end portion 130, which connects said end portions 110 and 130. Such terminals are made by cutting and folding a metal strip of small thickness of the order of 0.2 mm to several millimetres thick.

[0033] The distal end portion 110 corresponds to the contact zone of the female terminal 100. It is configured to be removably connected to a mating counter-terminal, i.e., a mating male terminal (not shown). The proximal end portion 130 comprises the crimping zone of the female terminal 100. The female terminal 100 is configured to be crimped, indeed, at level this crimping zone of the proximal end part 130, onto an electrical wire 200 having an electrically conductive multi-strand core 201 and an electrically insulating outer sheath 202. In this context, the terms "distal" and "proximal" are used here to distinguish the respective ends of terminal 100 with respect to their relative proximity to the associated wire 200 after said terminal has been crimped thereon.

[0034] By way of convention, spatially relative terms such as "rear" and "front", "behind" and "ahead", "back (or rear)" and "front", "backward" and "forward", and derivatives such as "in (the) front of", an "in the rear of" as well as associated verbs and derived nouns or expressions, are used herein in reference to the direction of insertion of the electrical wire 200 into the proximal portion 130 of terminal 100, with said wire 200 extending locally along the longitudinal axis X of said terminal 100. Based on this convention, the distal portion 110 of the female terminal 100 may also be referred to as the front part, and the proximal portion 130 may similarly be referred to as the rear part, respectively, of said terminal 100.

[0035] The front part 110 is configured to be mechanically and electrically connected to a complementary counter-terminal, such as a male electrical terminal comprising a mating contact blade. In case of a female terminal, indeed, the front part 110 is shaped as a contact cage configured to receive a mating contact blade of the male counter-terminal (not shown). This contact cage is extended rearwards by the intermediate portion 120 between the front portion 110 and the rear portion 130 of terminal 100. This cage 110 features a longitudinal seam zone 113 between opposing first and second folded portions 111 and 112, respectively, of the cage 110. This seam zone 114 results from the formation of the cage 110 by the folding, one toward the other, of portions 111 and 112 of a cut metal strip which mutually face each other along the transversal direction Y.

[0036] In the shown example, the contact cage 110 has a parallelepiped shape, i.e., it has a rectangular cross-section. It is elongated in the longitudinal direction X. Stater otherwise, its longer faces extend parallel to the longitudinal direction X of the terminal and its shorter faces extend perpendicular to said direction X and are front and rear faces. This is merely an example, as the shape of the contact cage 110 can also be cylindrical, i.e., it can have a rounded cross-section, either circular or elliptical for example. More generally, the contact cage can be configured to have a polygonal or rounded cross-section of any other type.

[0037] As can be seen in the cross-sectional view in Figure 4, the contact cage 110 may contain at least one arcuate contact spring blade 114, fixedly housed and arranged in electrical continuity with the inner walls of the contact cage. The role of this contact spring blade 114 is to improve contact with the mating contact blade of the connector's counter-terminal when said contact blade is inserted into the contact cage 110. For this technical effect to be effective and reliable, the arrangement of the contact spring blade 114 within the cage 110 must not be altered during the crimping operation.

[0038] The rear portion 130 of the terminal 100 has the shape of a semi-open barrel, configured to be closed over the wire 200 when the connection of said wire to said terminal is made. It comprises a crimping zone with shorter open wings 131a and 131b which are designed and intended to crimp the conductive core 201 of the wire 200 tightly to create electrical contact between the terminal 100 and the wire 200. These crimping wings 131a and 131b, when still open before crimping, extend somehow radially from opposite sides of the barrel base of the rear part 130 of terminal 100 with respect to the longitudinal axis X, in the same upward direction. In cross-section in a plane perpendicular to the longitudinal direction X at the crimping wings 131a and 131b, the rear portion 130 of terminal 100 is U-shaped, with a rounded lower part having a diameter that matches the outer diameter of core 201 at the stripped end of wire 200.

[0039] The rear portion 130 further comprises a stress-release or relaxation zone provided with open longer clamping wings 132a and 132b which are designed and intended to be tightly closed over and grip the insulating sheath of the electrical wire insulating sheath 202 of the electrical wire 200. The technical function of these clamping wings 132a and 132b is to absorb mechanical forces which would tend to pull the electrical wire 200 out of the closed barrel of terminal 100, in the event of mishandling of the assembly after crimping and throughout the operational life of the connection. When bent over the wire 200, the clamping wings 132a and 132b engage against the sheath 202 of said wire, either directly or via an intermediate element such as a protective sleeve, cable gland, clamping ring or sleeve, single-wire seal (SWS), etc. The bending of the clamping wings 132a and 132b does not primarily concern the proposed embodiments of the crimping process and crimping tool. Therefore, the operation of bending these wings will not be discussed in the present description. Nevertheless, according to embodiments, one and the same tool can be configured to implement the bending of the clamping wings 132a and 132b, in the same operation as the crimping of the crimping wings 131a and 131b or as a separate operation performed just before or just after said crimping.

[0040] The intermediate portion 120 forms a transition zone between the cage-shaped front part 110 and the semi-closed barrel-shaped rear part 130. It ensures both mechanical rigidity between the front portion 110 and the rear portion 130 of the 100 terminal, and electrical continuity between the contact cage of said front portion 110 and the wire 200 crimped in said rear portion 130. During compression of the crimping wings 131a and 131b on the stripped end portion 201 of the electrical wire 200, this transition portion 120 of the terminal 100 may deform, and more specifically extend transversally, responsive to the high compression forces exerted by the crimping tool on said crimping wings. As already mentioned in the introductory part of this description, this deformation of the transition zone 120 can lead to a subsequent and simultaneous deformation of the contact cage 110 of the terminal 100. Such an indirect deformation of the contact cage leads to drawbacks which the proposed embodiments aim to alleviate.

[0041] With further reference to Figure 5, there is shown therein a crimping tool 500 of the punch-anvil type, comprising a lower anvil 520 and an upper crimping punch 510 according to the prior art. This crimping tool 500 is adapted and configured to implement the crimping of an electrical terminal (be it a female or male terminal, actually) onto an electrical wire, such as terminal 100 and wire 200, respectively, which are shown in Figure 1.

[0042] This punch 510 has substantially the shape of a parallelepiped plate, elongated in the vertical direction Y between an upper end (not shown in the partial view of figure 5) and a lower end. The lower end of the punch 510 comprises a crimping gripper 511 with two crimping teeth 511a and 511b which are separated laterally by a notch 513. The width of the notch 513 in the transversal direction Y decreases from the lower end of the teeth 511a,511b towards the upper bottom of the notch 513, from which the teeth extend downwardly. The plate has a thickness LA in the longitudinal direction X which corresponds to, i.e., is substantially the same as, the length L 1 of the crimping wings 131a and 131b of the terminal 100 in said direction (see Figure 2 and Figure 3).

[0043] This notch 513 extends vertically from the lower end of the punch 510. All included, it has substantially an "inverted W" shape in cross-section in a plane perpendicular to the longitudinal direction X - given that the terminal to which the XYZ referential is associated is intended to be positioned in the crimping tool 500 comprising said punch 510, below the punch 510 and with its longitudinal axis X extending perpendicular to the main plane of said punch. Notch 513 corresponds to the part of punch 510 that enables the two crimping wings 131a and 131b to be formed during the crimping process, by a relative upward movement of terminal 100 towards the bottom at the top of notch 513.

[0044] To that end, the notch 513 more precisely has a V-shaped, relatively large lower opening, making it possible for the two wings 131a and 131b - as far as they are in a V-configuration relative to the base of the terminal in which their free ends are not spaced along the transversal direction Y by a larger distance than the width of the V-shaped notch's opening - to engage into the notch 513. Above this opening, the notch 513 presents a thinner channel with substantially parallel walls to bring the two wings 131a and 131b together. Finally, the upper bottom of the notch 513 has two laterally adjacent grooves, which extend longitudinally and have a rounded shape in cross-section. The length of these grooves along the longitudinal direction X is L 1 . This configuration of the notch 513, overall, makes it possible for the two crimping wings 131a and 131b to be simultaneously curved down progressively on top of the stripped end portion 201 of the wire 200, then to be move further downwardly toward said stripped end portion 201 of the wire 200 and eventually to engage into it by insertion between the wire strands.

[0045] The anvil 520 has an upper chappe 521 adapted to retain the terminal 100 to be crimped from below, while the punch 510 is moved downwards, towards the anvil and thus towards said terminal 100. This prevents the terminal 100 from moving downwards in reaction to pressure forces applied from above by the punch 510 when the latter is moved downwards, which otherwise would occur as soon as the punch contacts with the terminal 100.

[0046] Hence, crimping wings 131a and 131b of terminal 100 are engaged within the notch 613, between the mutually facing lateral surfaces of the teeth 511a and 511b, and are pressed from top to bottom by the downward movement of the punch 610. Each of the crimping wings 131a and 131b are bent, first slightly towards each other along the transverse direction Y, then downwards along the vertical direction Z after a U-turn of their respective free end caused by the mechanical reaction of the bottom of the notch 513. In response to the continued downward movement of the punch 510, these free ends of the crimping wings 131a and 131b move down towards the stripped portion 201 of the wire 200, and eventually into the strands of said wire 200.

[0047] This trajectory and the associated deformations of the crimping wings 131a and 131b are obtained by reaction of the inner walls of the notch 513 of the punch 510, against which the crimping wings 131a and 131b are forced to slide and thus adopt their shape due to their relative thinness compared to the much more massive teeth 511a and 511b, respectively, of said punch 510. When the crimping operation is complete, the punch 510 is raised, namely is brought back upwards, to release the assembly formed by the wire 200 over which the terminal 100 is crimped.

[0048] The skilled person will appreciate that, in the above description of the crimping process, it is assumed that the punch 510 is vertically mobile while the anvil 520, which supports the terminal 100 to be crimped at the start of and during the process, is fixed and therefore remains stationary. This configuration determines the name given to these two components of the anvil-punch type crimping tool 500 in common language. Due to the relativity of the movement of the two parts 510 and 520 one relative to the other, however, the same crimping result can be achieved by providing the lower component 520 as a vertically movable element and the upper component 510 as a fixed element. In another variant, the two components 510 and 520 of the crimping toll 500 can be controlled to move vertically towards each other during the crimping process.

[0049] Figure 6A to Figure 6C illustrate a punch 610 of a crimping toll 600 according to embodiments proposed herein. Like the punch 510 of tool 500 according to the prior art already described above with reference to Figure 5, this punch 610 has substantially the shape of a parallelepiped plate, elongated in the vertical direction Z between an upper end and a lower end.

[0050] Further, the lower end of the proposed punch 610 is also shaped with at least one pair of laterally spaced crimping teeth 511a and 511b, which form a crimping gripper 511, exactly like the punch 510 of Figure 5. In addition, the proposed punch 610 further comprises at least one retaining flange 630 with at least one pair of laterally spaced retaining jaws 631a and 631b. As best shown in the magnified detail in Figure 6A, the retaining flange 630 is adjacent to and ahead of the crimping gripper 511 along the longitudinal direction X. Preferably, the distance along the longitudinal direction X between a central point of the gripper 511 and a central point of the retaining flange 630 corresponds substantially to the distance along said longitudinal direction X between a central point of the crimping wings 131a,131b and a central point of the transition portion 120, respectively, of the terminal 100.

[0051] With particular reference the front view in Figure 6B, the punch 610 has a W-shape in cross-section at level of the crimping gripper 511. Thanks to this shape, the punch 610 is configured to compress and deform the crimping wings 131a and 131b of the electrical terminal 100 upon crimping. This has already been described above and this description shall not be repeated here, for reasons of brevity of the present disclosure.

[0052] Let us turn now to the retaining flange 630 which is specific to embodiments. The retaining jaws 631a and 631b of said retaining flange 630 are configured to hold the transition part 120 of the electrical terminal 100 firmly gripped therebetween during crimping. Being so retained the transition part 120 cannot widen laterally while the crimping wings 131a and 131b are compressed by the crimping punch 610 (and deformed by the crimping teeth 511a and 511b) during the crimping process. This prevents the contact cage 110 of the female terminal 100 from opening by lateral spreading of its opposing folded portions 11 and 112 away from the longitudinal seam zone 113.

[0053] Stated otherwise, this prevents the contact cage 110 from opening at level of its rear end close to the transition portion 120 of the terminal 100, which could otherwise be caused by high pressure applied by the crimping tool 600 for crimping said terminal 100 onto the electrical wire 200. That way, in particular, the arcuate contact spring 114 mounted in the contact cage 110 does not run the risk of being displaced within said contact cage 110.

[0054] In one example as shown in the figures of the drawings, the retaining jaws 631a and 631b of the retaining flange 630 are separated from each other in a transversal plane containing them.

[0055] In a variant, the retaining flange 630 can be an integral element having an inverted, substantially U-shape in cross-section whose respective legs form the pair of retaining yaws 631a and 631b. This may provide more solidity to the retaining yaws.

[0056] As shown in the drawings, the retaining flange 630 is preferably integral with the punch 510. For example, the retaining jaws 631a and 631b can be machined from the same metal workpiece as the crimping teeth 511a and 511b, so that the entire punch 610 is in one piece. This has the advantage of simplicity of manufacture and operational robustness of the punch 610.

[0057] In one variant, however, the retaining flange 630 can be a separate element from the main body of the punch 510, and be removably attached to said body, for example by screwing or riveting. This makes it possible to upgrade existing crimping tools by adding functional features as proposed herein. Also, this allows having interchangeable retaining flanges which can be selected for crimping any specific type of terminal.

[0058] Preferably, the length L B of the retaining flange 630, that is the length of the retaining jaws 631a 631b along the longitudinal direction X can correspond substantially to the length L 2 of the transition portion 130 of the terminal 100 along said direction (see again Figures 2 and 3). That way, the mechanical efforts for retaining the transition portion 120 are well balanced over the longitudinal length of said portion. This reduces mechanical stress, in favour of respecting the integrity of the terminal 100.

[0059] In some embodiments, the respective surfaces of the retaining jaws 631a and 631b which face each other along the transversal direction Y, are so curved that a first distance between them along said transversal direction Y at a relative lower height along the vertical direction Z is larger than a second distance between them along said transversal direction Y at a relative upper height along said vertical direction Z. Thanks to this feature, the transition portion 120 of the terminal 100 is smoothly guided into the retaining flange 630 when the punch 610 is moved down into the direction of said terminal for crimping.

[0060] For example, the radius of curvature of the respective surfaces of the retaining jaws 631a and 631b facing each other along the transversal direction Y has a first value at a relative lower height along the vertical direction Z and a second value, greater than said first value, at a relative higher height along said vertical direction Z. Also, this further eases the release of the crimped terminal 100 when from the punch 610 when said punch is raised after completion of the crimping process.

[0061] The crimping process using the crimping tool 600 with a punch 610 according to embodiments, is illustrated by the series of pictures in Figure 7A, Figure 7B and Figure 7C, respectively.

[0062] More particularly, Figure 7A illustrates the crimping tool 600 according to embodiments, with a female electrical terminal 100 positioned therein, ready for initiation of the crimping operation. Before starting the crimping process as such, indeed, there must be provided an assembly as shown, comprising an electrical female terminal 100 and an electrical wire 200 locally extending along the longitudinal direction X of said terminal, and having a stripped end portion 201 comprising a plurality of electrically conductive strands, to be crimping between the crimping wings 311a and 311b of the terminal 100.

[0063] Figure 7B illustrates an intermediate stage in the crimping process, in which the crimping wings 311a and 311b of the terminal 100 enter into sliding contact with the opposing inner surfaces of the crimping pliers 511, i.e. the surfaces of the crimping teeth 511a and 511b that face each other along the transverse direction Y. At this stage of the process, the pressure forces exerted by punch 610 on terminal 100 are still relatively low. As can be seen, the transition portion 120 of the terminal 100 between the contact cage at the front and the crimping wings 131a and 131b at the rear is not yet in mutual engagement with the retaining jaws 631a and 631b.

[0064] As shown in Figure 7C the crimping operation ends up when the terminal is fully compressed between the punch 610 and the chappe 521 of the anvil 520. The crimping wings 131a and 1331b have then be totally curved down in the strands of the stripped end portion of the electrical wire (not visible in the Figure). The skilled person will note from the Figure that the transition portion 120 of the terminal 100 is firmly hold between the retaining yaws 631a and 631b of the retaining flange 630. That way, the transition portion 120 has not been able to expand laterally along the transversal direction Y. Thanks to this holding the integrity of the contact cage 110 is preserved during the crimping process. It does not open since the transition portion 120 cannot widen along the transversal direction Y albeit high pressure forces exerted by the punch 610.

[0065] After completion of the crimping operation, the punch 610 is raised, releasing the terminal 100 crimped over the stripped end portion 201 of the electrical wire 200. The terminal 100 can then be removed from the crimping tool 600, along with the electrical wire 200 attached thereto by crimping.

[0066] The use of a crimping tool with a punch as proposed herein results in a more reliable functional behaviour of the female electrical terminal after crimping onto an electrical wire, which remains compliant with technical specifications, even if a higher than usual pressure is applied, and / or even if a wire with a larger than usual cross-section is used.

[0067] In particular, this reduces the risk that the operability or at least the effectiveness of any arcuate contact spring mounted in the contact cage to improve contact with the mating blade of the connector's counter-terminal, will be compromised due to unwanted and uncontrolled deformation of the contact cage during the crimping process.

[0068] While there has been illustrated and described what are presently considered to be the preferred embodiments of the present invention, it will be understood by those skilled in the art that various other modifications may be made, and equivalents may be substituted, without departing from the true scope of the claims. Additionally, many modifications may be made to adapt a particular situation to the teachings of the present disclosure without departing from the central inventive concept described herein. Furthermore, an embodiment of the present invention may not include all of the features described above. Therefore, it is intended that the proposed solution be not limited to the particular embodiments disclosed, but includes all embodiments falling within the scope of the appended claims.

[0069] A person skilled in the art will readily appreciate that various parameters disclosed in the description may be modified and that various embodiments disclosed and / or claimed may be combined without departing from the scope of the solution as claimed.

[0070] Expressions such as "comprise", "include", "incorporate", "contain", "is" and "have" are to be construed in a non-exclusive manner when interpreting the description and its associated claims, namely construed to allow for other items or components which are not explicitly defined also to be present. Reference to the singular is also to be construed in be a reference to the plural and vice versa. Finally, it is stipulated that the reference signs in the claims do not limit the scope of the claims but are merely inserted to enhance the legibility of said claims.

Claims

1. A method of crimping a female electrical terminal (100) onto a multi-strand electrical wire (200), comprising: - providing an assembly comprising: ∘ an electrical wire (200) locally extending along a longitudinal direction (X) and having a stripped end portion (201) comprising a plurality of electrically conductive strands, ∘ an electrical female terminal (100) comprising at least the following parts provided along a longitudinal direction (X): ▪ a proximal part (110), shaped as a contact cage configured to receive a mating contact blade of a male counter-terminal, said contact cage featuring a longitudinal seam zone (113) between opposing first and second folded portions (111,112) of the cage (110) resulting from the formation of said cage by the folding of a cut metal strip; ▪ a distal part (130) forming a crimping zone, shaped as a semi-open barrel with at least one pair of crimping wings (131a, 131b) configured to be crimped onto a stripped end portion (220) of the electrical wire (200) to create an electrical contact between the terminal (100) and the electrical wire (200); and, ▪ a transition part (120), arranged between and configured to join the first longitudinal part (110) and the second longitudinal part (130), a crimping segment (130) with a semi-open barrel-shaped base configured to receive the electrical wire (2) and having at least one pair of individual crimping wings (131a,131b) each extending substantially vertically and having a connection end connected to the barrel (3) and a free end opposed to the connection end, said crimping wings facing each other on either side of the barrel and having a determined length (L1) along the longitudinal direction (X), said stripped end portion (201) of said electrical wire (2) extending into said barrel between said crimping wings (131a, 131b), - said method further comprising: ∘ compressing the crimping wings (131a,131b) of the electrical terminal (100) to deform them for crimping; and, ∘ simultaneously holding the transition part (120) of the electrical terminal (100) retained between laterally spaced retaining jaws (631a, 631b) so as to prevent said transition part (120) widening laterally while the crimping wings (131a,131b) are compressed during the crimping.

2. A crimping tool of the stamp-anvil type having a punch (600) for crimping a female electrical terminal (100) onto a multi-strand electrical wire (200), said terminal (100) comprising at least the following parts provided along a longitudinal direction (X): - a proximal part (110), shaped as a contact cage configured to receive a mating contact blade of a male counter-terminal, said contact cage featuring a longitudinal seam zone (113) between opposing first and second folded portions (111,112) of the cage (110) resulting from the formation of said cage by the folding of a cut metal strip; - a distal part (130) forming a crimping zone, shaped as a semi-open barrel with at least one pair of crimping wings (131a,131b) configured to be crimped onto a stripped end portion (220) of the electrical wire (200) to create an electrical contact between the terminal (100) and the electrical wire (200); and, - a transition part (120), arranged between and configured to join the first longitudinal part (110) and the second longitudinal part (130), wherein the punch (610) comprises at least one crimping gripper (511) with a pair of laterally spaced crimping teeth (511a, 511b) and at least one retaining flange (630) with at least one pair of laterally spaced retaining jaws (631a, 631b), said retaining flange (631a, 631b) being adjacent to and ahead of said crimping gripper (511) along the longitudinal direction (X), and wherein: - the punch has a W-shape in cross-section at level of the crimping gripper (511a,511b), configured to compress and deform the crimping wings (131a, 131b) of the electrical contact terminal upon crimping; and, - the retaining jaws (631a,631b) of the retaining flange (630) are configured to hold the transition part (120) of the electrical terminal (100) firmly gripped therebetween during crimping so as to prevent said transition part (120) from widening laterally, while the crimping wings (131a,131b) are compressed by the crimping gripper (511) for crimping.

3. A crimping tool according to Claim 2, wherein the retaining flange (630) is an integral element having an inverted, substantially U-shape in cross-section whose respective legs form the pair of retaining yaws (631a,631b).

4. A crimping tool according to Claim 2, wherein the retaining jaws (631a, 631b) of the retaining flange (630) are separated from each other in a transversal plane containing them.

5. A crimping tool according to any one of claims 2 through 4, wherein the retaining flange (630) is integral with the punch (510).

6. A crimping tool according to any one of claims 2 through 4, wherein the retaining flange (630) is separate from the punch (510) and detachably fastened to said punch (510).

7. A crimping tool according to any one of claims 2 through 6, wherein the length (LB) of the retaining flange (631a,631b) along the longitudinal direction (X) corresponds substantially to the length (L2) of the transition part (130) of the terminal (100) along said direction.

8. A crimping tool according to any one of claims 2 through 7, wherein the respective surfaces of the retaining jaws (631a,631b) which face each other along the transversal direction (Y), are so curved that a first distance between them along said transversal direction (Y) at a relative lower height along the vertical direction (Z) is larger than a second distance between them along said transversal direction (Y) at a relative upper height along said vertical direction (Z).

9. A crimping tool according to Claim 8, wherein the radius of curvature of the respective surfaces of the retaining jaws (631a,631b) facing each other along the transverse direction (Y) has a first value at a relative lower height along the vertical direction (Z) and a second value, greater than said first value, at a relative higher height along said vertical direction (Z).

Images