Method for producing a contact plug and contact plug

Abstract

Method for producing a contact plug, comprising the following process steps: - providing a blank (4) comprising or consisting of a lead-free brass alloy; - semi-hot forming of a first section (6) of the blank (4) to form a crimping region (6), wherein the crimping region (6) has an opening (10) for inserting a conductor end and wherein the first section (6) of the blank (4) is heated to a semi-hot forming temperature before and / or during the semi-hot forming; - cold forming a second section (14) of the blank (4) to form a plug-in region (14), wherein the plug-in region (14) has a plurality of lamellae (26).

Description

The present invention relates to a method for producing a contact plug and to a contact plug.Contact plugs are usually produced by machining lead-containing copper and brass alloys. The machinability of blanks is improved by alloying lead. Due to the proven health-damaging effect of lead, the use of lead is increasingly restricted normatively.In principle, in the production of contact plugs which have a crimp terminal, there is the challenge of providing a material which, on the one hand, is readily cuttable and, on the other hand, has a sufficiently high cold workability in order to produce durable, crack-free crimp connections in a reliable manner. This compromise is nowadays achieved by lead-containing copper or brass alloys which, on the one hand, can be readily machined and, in addition, can be crimped without cracking.For lead-free brass alloys, such a compromise between good machinability, i.e. brittle-hard behavior, and crimpability, which requires high ductility, cannot be achieved in a manner suitable for practice. Thus, crimped connections made of brass alloys tend to crack.Furthermore, the machining of lead-free brass alloys requires high machining forces, which can usually only be achieved with cooled drills in a reliable manner, which leads to increased production costs. In addition, there is the fundamental disadvantage in the machining process that a material loss of up to 50% is accepted.DE 196 53 441 A1 discloses a plug contact sleeve having a receiving part for a plug and a side connection part. The receiving part forms a sleeve with a base, two side walls and a roof region, wherein the roof region has at least two tongues which extend transversely to the plug-in direction and which start alternately from different side walls and are bent over inward into the sleeve in the upper region of the opposite side walls.U.S. Pat. No. 4,025,367 A discloses a method for improving the thermal stability of copper alloys with a low stack defect energy. The method includes cold working the alloy, heating the alloy to a first temperature of 100° C. to 300° C., additionally heating the alloy to a second temperature of 200° C. to 360° C., and cooling to room temperature. The second temperature must be higher than the first temperature.Against this background, the invention is based on the technical problem of specifying a method for producing a contact plug and a contact plug which do not have the disadvantages described above or at least to a lesser extent, and in particular make possible a lead-free contact plug which provides a sufficiently high and in particular crack-free deformability in a crimping region.The technical problem described above is solved in each case by a method according to claim 1 and a contact plug according to claim 9.According to a first aspect, the invention relates to a method for producing a contact plug, comprising the method steps: providing a blank which comprises a lead-free brass alloy or consists of a lead-free brass alloy; semi-hot forming a first section of the blank into a crimping region, wherein the crimping region has an opening for inserting a conductor end and wherein the first section of the blank is heated to a semi-hot forming temperature before and / or during the semi-hot forming; cold forming a second section of the blank into a plug region, wherein the plug region has a plurality of fins.The indicated temperature control enables the crimping region to be provided with a structure which has low work hardening and thus has a high ductility for a crimping operation. Thus, a reliable crimping of a conductor end with the crimping region can be carried out without cracking occurring in the region of the crimped connection.The cold forming of the plug-in region leads to a work hardening, so that the plug-in region is not deformed, or is deformed only to a slight extent, plastically when a plug-in connection is produced, and is significantly elastically deformed in order to provide corresponding spring forces reversibly.The above list of method steps does not specify a obligatory sequence of method steps. Thus, the method steps can be carried out in the order of the listing, or in an order differing therefrom. For example, it can be provided that, deviating from the sequence of the listing, cold forming of the second section takes place before the half-hot forming of the first section.According to a further embodiment of the method, it is provided that the half-hot forming temperature is in a range from 250° C. to 450° C. inclusive. Thus, the half-hot forming temperature can be 350° C., for example.If cold forming is mentioned here, this is forming at a temperature below the half-hot forming temperature.The cold forming can take place at a temperature of less than 100° C., in particular at a temperature of less than 50° C., further in particular at room temperature in a range from 15° C. to 30° C.It is understood that the temperatures mentioned identify the material temperature of the component to be formed. The ambient temperature may vary therefrom and may be, for example, 25° C.According to a further embodiment of the method, it can be provided that the second section is cooled before and / or during the cold forming of the second section. It can thus be avoided that, for example, a temperature input from a preceding half-hot forming leads to a heating of the second section above a provided cold forming temperature.Alternatively or additionally, it can be provided that the first section is cooled before and / or during the cold forming of the second section. Thus, the first section can be heated, for example, from a preceding half-hot forming, wherein a heat flow towards the second section is avoided or reduced by the cooling.According to a further embodiment of the method, it can be provided that the second section is cooled before and / or during and / or after the heating of the first section. Alternatively or additionally, it can be provided that the temperature of the second section is at all times below 100° C., in particular below 50° C., in particular is kept in a range from 15° C. to 30° C. at room temperature, before and / or during and / or after the forming of the first and second sections.The term "at any time" refers here to the time duration of the production process in question.By cooling the first and / or second section, it can be ensured that the desired work hardening occurs in the second section despite the heating of the first section.A further configuration of the method is characterized in that a partial region of the crimping region formed by half-hot forming is cold-formed after the half-hot forming. For example, an end section of the crimping region can be formed into a circumferential collar which, as a result of work hardening, locally has a higher strength than the part of the crimping region adjoining it.The plates can be axially projecting spring webs. Alternatively or additionally, the lamellae can be arranged at equidistant angular distances around a central opening. Alternatively or additionally, axial slots can be formed between the plates. With the aid of the lamellae, a reliable plug connection can be provided.According to a further embodiment of the method, cooling takes place by means of a cooling device held on a pressing tool or integrated into a pressing tool. Alternatively or additionally, heating is carried out by means of a heating device held on a pressing tool or integrated into a pressing tool, such as an induction heating device, a resistance heating device or the like. Thus, the cooling and heating device can be compactly integrated into a pressing tool and can be connected as required.It can be provided that the forming, i.e. both the hot forming and the cold forming, takes place with the aid of a multistage press, wherein the multistage press has at least one heating device and at least one cooling device. As described above, a heating and cooling device can be integrated in tools of the multistage press.According to a second aspect, the invention relates to a contact plug which comprises a lead-free brass alloy or consists of a lead-free brass alloy, having a crimping region, wherein the crimping region has an opening for inserting a conductor end, and having a plug region, wherein the plug region has a plurality of lamellae, wherein the crimping region has, at least in sections, a lower degree of work hardening than the plug region. Thus, on the one hand, good crimpability of the crimp region and also sufficient strength and rigidity of the lamellae can be achieved. It is understood that this is a comparison of the work hardening of the crimping region with respect to that of the plug region before an actual crimping of a conductor end in the crimping region.It can be provided that the contact plug has been produced according to a method according to the invention.It can be provided that the contact plug comprises a lead-free brass alloy CuSn36, CuSn30, CuSn20, CuSn15or CuSn5, or consists of a lead-free brass alloy CuSn36, CuSn30, CuSn20, CuSn15or CuSn5.The invention is described in more detail below with reference to a drawing illustrating exemplary embodiments. They show in each case schematically: FIG. 1 shows a provision of a blank; FIG. 2 shows a half-hot forming of a first section of the blank; FIG. 3 shows cold forming of a second section of the blank; FIG. 4 shows a further cold forming of the second section; FIG. 5 shows cold forming of an end section of the first section; FIG. 6 shows a contact plug according to the invention.Referring to FIGS. 1-5, a method of manufacturing a contact plug according to the present invention will first be described. A contact plug 2 produced by the method according to the invention is illustrated in FIG. 6.For producing the contact plug 2, a blank 4 is first provided which consists of a lead-free brass alloy.After the blank 4 has been provided, a first section 6 of the blank 4 is formed into a crimping region 6 by half-hot forming. An opening 10 for inserting a conductor end is formed on the crimping region 6 with the aid of a tool 8. The first section 6 is heated in the present case before and during the half-hot forming to a half-hot forming temperature of 350° by means of an induction heating device 12.During the semi-driver semi-hot forming of the first section 6, a second section 14 of the blank 4 is actively cooled with the aid of a cooling device 16. The cooling device 16 has cooling channels 18 which guide a cooling fluid.Subsequently, cold forming of the second section 14 illustrated in FIG. 3 takes place, wherein during the cold forming of the second section 14, the first section 6 is cooled with the aid of a cooling device 20 which has cooling channels 22 for guiding a cooling fluid.As can be seen from FIGS. 2 and 3, the heating device 12 and the cooling devices 16, 22 are integral components of tools which enclose the blank 4 during the forming.FIG. 4 shows a further cold forming of the second section 14 to form a plug region 14, wherein lamellae 26 are formed on the second section 14 with a tool 24.The lamellae 26 are axially projecting spring webs which are arranged around a central opening at equidistant angular distances. Axial slots 38 are formed between the plates 26.In a final forming step, according to FIG. 5, a partial region 28 of the crimping region 6 formed by half-hot forming is cold-formed. The region 28 forms a collar 28 which extends around in a circular manner.By the production method according to the invention described with reference to FIGS. 1-5, a first longitudinal section 30 of the contact plug 2 is provided with a work-hardened region (cf. FIG. 6 ) to which a longitudinal section 32 with a lower work-hardening is connected, which forms a ductile crimping region. Along the length section 34, the strength of the contact plug 2 substantially corresponds to that of the originally provided blank 4. Along the length region 36 in which the lamellae 26 have been formed by cold forming, the cold solidification is the highest, since here the highest degrees of forming have been effected.Reference numerals denote reference numerals2 Contact plug 4 Blank 6 First section / crimping region 8 Tool 10 Opening 12 Induction heating device 14 Second section / plug region 16 Cooling device 18 Cooling channel 20 Cooling device 22 Cooling channel 24 Tool 26 Lamellae 28 Partial region / circumferential collar of the crimping region 6 30 Longitudinal section 32 Longitudinal section 34 Longitudinal section 36 Longitudinal section 38 Slot

Claims

Method for producing a contact plug, having the method steps: - providing a blank (4) which comprises a lead-free brass alloy or consists of a lead-free brass alloy; - semi-hot forming a first section (6) of the blank (4) to form a crimping region (6), wherein the crimping region (6) has an opening (10) for inserting a conductor end and wherein the first section (6) of the blank (4) is heated to a semi-hot forming temperature before and / or during the semi-hot forming; - cold forming a second section (14) of the blank (4) to form a plug region (14), wherein the plug region (14) has a plurality of lamellae (26).The method of claim 1, wherein the half-hot forming temperature is in a range of 250°C to 450°C, inclusive.Method according to Claim 1 or Claim 2, characterized in that - the second section (14) is cooled before and / or during the cold forming of the second section (14); and / or - the first section (6) is cooled before and / or during the cold forming of the second section (14).Method according to one of Claims 1 to 3, characterized in that - the second section (14) is cooled before and / or during and / or after the heating of the first section (6) and / or - the temperature of the second section (14) before and / or during and / or after the shaping of the first and second sections (6, 14) is at all times below 100°C.Method according to one of Claims 1 to 4, characterized in that - a partial region (28) of the crimping region (6) formed by half-hot forming is cold-formed after the half-hot forming.Method according to one of Claims 1 to 5, characterized in that - the plates (26) are axially projecting spring webs (26), and / or - the plates (26) are arranged at equidistant angular spacings around a central opening, and / or - axial slots (38) are formed between the plates (26).Method according to one of Claims 1 to 6, characterized in that - cooling is effected by means of a cooling device (16, 20) held on a pressing tool or integrated in a pressing tool, and / or - heating is effected by means of a heating device (12) held on a pressing tool or integrated in a pressing tool, such as an induction heating device (12), a resistance heating device or the like.Method according to one of Claims 1 to 7, characterized in that - the forming is carried out with the aid of a multistage press, - the multistage press having at least one heating device (12) and at least one cooling device (16, 20).Contact plug, - which comprises a lead-free brass alloy or consists of a lead-free brass alloy, - with a crimping region (6), wherein the crimping region (6) has an opening (10) for inserting a conductor end, and - with a plug region (14), wherein the plug region (14) has a plurality of lamellae (26), - wherein the crimping region (6) has, at least in sections, a lower work hardening than the plug region (14).Contact plug according to Claim 9, - wherein the contact plug (2) has been produced by a method according to one of Claims 1 to 8, and / or - the contact plug (2) has a lead-free brass alloy CuZn36, CuZn30, CuZn20, CuZn15 or CuZn5, or consists of a lead-free brass alloy CuZn36, CuZn30, CuZn20, CuZn15 or CuZn5.

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