METAL BAND AND PROCEDURE FOR THE PRODUCTION OF SUCH A METAL BAND

Abstract

A metal strip (1, 101, 201) and a method for producing such a metal strip (1, 101, 201) are shown. To enable the reproducible production of a stable metal strip (1, 101, 201), it is proposed that the butt seam (5) extend essentially between the first plated layer (3b) of the first strip cross-section (2a) and the second strip cross-section (2b).

Description

METAL BAND AND PROCEDURE FOR THE PRODUCTION OF SUCH A METAL BAND Technical field The invention relates to a metal band and to a process for producing such a metal band. State of the art For the production of a hybrid metal strip for electrotechnical applications of two metal strips joined longitudinally together of different base metals - for example aluminum and copper - it is known to weld the two metal strips on the longitudinal side butt to each other. This leads to the formation of undesirable intermetallic phases in the molten metal, which impair the stability or quality of the weld joint and thereby compromise the mechanical and functional safety of the metal strip during subsequent processing. Furthermore, these intermetallic phases reduce electrical conductivity, limiting the use of the metal strip for producing electrically conductive structural components. These components also exhibit reduced load-bearing capacity. To minimize the formation of such undesirable intermetallic phases, expensive welding methods are available, such as ultrasonic welding or stir friction welding. However, these methods are not suitable for continuous production. As an alternative to welding, metal strips with different base metals can also be joined by adhesion using a cladding process. However, cladding by lamination is limited by the strength of the bonding materials—in particular, it is not possible, or nearly so, to clad a copper or copper alloy strip with a tensile strength (Rm) of 360 MPa, so for these metal strips, welding must be used—with all the associated disadvantages in the weld area. Description of the invention The invention has therefore set out the objective of modifying a metal band described at the beginning of two metal bands joined longitudinally together with different base metals so that it can achieve, without limitation on resistance, a comparatively high mechanical stability and / or high electrical conductivity. Furthermore, the objective of the invention is to facilitate a reproducible, simple and / or economical procedure for the production of a metal band of this type. The invention solves the objective set regarding the metal band through the features of claim 1. If the first metal band has a first layer of copper or a copper alloy plated, provided at least along one longitudinal edge over the first base layer, a mechanically and / or electrically effective bond between the first cross-section of the band, which has a first base layer of aluminum or an aluminum alloy, and the second cross-section of the band, which has a second base layer of copper or a copper alloy with a resistance > 360 MPa, can be ensured.The multi-layered structure of the first metal strip along its longitudinal edge, or longitudinal side, specifically opens up the possibility of extending the butt seam essentially between the first plated layer of the first cross-section of the strip and the second cross-section of the strip, so that no disadvantageous or negligible intermetallic phases are to be expected in the butt seam. Therefore, the butt seam also does not present any brittle phases that reduce electrical resistance or conductivity, making the metal strip according to the invention particularly suitable, for example, for electrical components such as contacts. Furthermore, the metal strip according to the invention does not experience the reduced stability known to other metal strips – thus ensuring effective end products. This is particularly true given that the second strip section offers a comparatively high tensile strength (Rm) of 360 MPa. The metal band according to the invention can stably combine within itself the most diverse properties of different groups of materials. In particular, the metallic strip may be suitable for electrical applications when the aluminum alloy has an electrical conductivity of at least 9 MS / m (Megasiemens / m). Preferably, the first base layer has an electrical conductivity of at least 18 MS / m. The occurrence of these undesirable intermetallic phases can be further mitigated by extending the butt seam exclusively between the first veneered layer and the second cross-section of the strip. Preferably, the butt seam is extended exclusively between the first veneered layer and the second base layer. Preferably, the first cross-section of the strip has a first strip thickness, which is greater than or equal to the second strip thickness of the second cross-section of the strip, in order to facilitate, for example, a semi-finished product individually adapted for further processing. cccfrnn / eznz / E / YiAi A high-quality butt seam can result when, for example, the second cross-section of the band in its second band thickness is less than or equal to that layer thickness of the first plated layer, to which the second cross-section of the band is connected. It can be especially advantageous when there is a thickness ratio of the first band thickness of the first band cross-section to the second band thickness of the second band cross-section of 1:1 to 1:0.2, in particular from 1:0.6 to 1:0.7. Preferably, the second base layer of the second metal band or of the second cross-section of the band is made of a curable copper alloy. This second base layer may have a CuNiSi base. Preferably, the second base layer is made of an alloy of CuNH₄Si, CuNi₃SiMg, or CuNi₂SiSn. Alternatively, it is conceivable that the second base layer is made of a low-alloy copper alloy, specifically for example a CuFe2P alloy. It is also conceivable that the second base layer is made up of a Cu-Sn alloy, specifically for example a CuSn6 alloy in the cold solidified state. Furthermore, it is conceivable that the second metallic band may have an inorganic coating. This coating is preferably formed on the second base layer. This coating can be formed, for example, by a hot tinning process with, for example, 2–10 µm of tin, or by an electroplating process with, for example, 1–3 µm of nickel flash and, on top of this, for example, 2–6 µm of tin. If the first plated layer, for example, has a tensile strength (Rm) < 420 MPa, a stable bond between materials can be ensured in the base layer or in another layer of the first metal strip. This is particularly effective when the first plated layer has a tensile strength (Rm) < 360 MPa. Preferably, the first plated layer is made of copper, specifically for example copper with the material designation EN CW008A. Alternatively, it is conceivable that the first plated layer is made of a low-alloy copper alloy. Furthermore, a first layer of a CuSn alloy is conceivable, specifically for example a CuSn6, for example in the soft / soft annealed state. cccfrnn / cznz / E / YiAi The formation of harmful intermetallic phases can be further contained when the first cross-section of the strip has a re-entrant notch relative to the plated layer on the longitudinal edge. This notch can be configured, for example, as a chamfer or fold. Preferably, the first plated layer and the first base layer are plated by lamination, which can create a comparatively stable bond of the plated layer to the base layer. Additionally, a stable welded joint can be achieved when the butt seam is configured as an I-seam. In particular, the metal strip according to the invention may be suitable as a semi-finished product or starting material to produce with it at least one electrical component, for example an electrical contact, for example by means of a stamping process. The invention solves the objective set out regarding the procedure for the production of the metal band by means of the characteristics of claim 12. Since the first and second metal strips are welded continuously along their longitudinal edges in a butt joint, with the second metal strip essentially butt-jointed to the first layer, the intermetallic phases that typically occur during the welding of different material groups—phases that have a detrimental effect on the weld bead's stability—can be eliminated. To achieve this, the first layer is applied at least along the longitudinal edge of the first metal strip over the first base layer. The first metal strip is therefore multi-layered along this longitudinal edge. This significantly increases the reproducibility of the process for producing the metal strip according to the invention. Preferably, the first metal strip and the second metal strip are welded continuously together for this purpose. This reproducibility of the procedure can be further improved when the second metal band connects exclusively with the first butt-plated layer - in particular when the second base layer connects exclusively with the first butt-plated layer. Welding the first and second metal strips together using a radiation welding process can further increase the reproducibility of the procedure for producing a stable metal strip. The use of a laser can be particularly advantageous for the radiation welding process. With this laser, a narrow butt weld can be generated, and / or disadvantageous intermetallic phases can be reduced or even avoided altogether due to the comparatively low heat flux zones. Preferably, the first plated layer and the first base layer are laminated to create reproducibly a first multi-layered metallic band with high layer cohesion. For example, by giving the first metal strip an inward notch with respect to the plated layer on the longitudinal edge before welding, in particular a chamfer or a fold, the risk of formation of harmful intermetallic phases in the weld bead due to mixing of the first and second base layers can be further reduced. Brief description of the drawings The Figures illustrate in more detail, for example, the object of the invention by means of several embodiments. Figure 1 shows a side view of a transversely cut metal strip according to a first embodiment, Figure 2 shows a side view of a transversely cut metal strip according to a second embodiment, and Figure 3 shows a side view of a transversely cut metal strip according to a third embodiment. According to FIG. 1, for example, a metal band 1 is represented according to a first embodiment, which has a first cross-section of band 2a and a second cross-section of band 2b. The first cross-section of band 2a is formed by a first metal band 3, the second cross-section of band 2b is formed by a second metal band 4, which are connected by material adhesion to each other - and specifically through a butt seam 5 that runs along the length of the metal band 1. This butt seam 5 extends continuously in the longitudinal direction L of the metal band 1. The first metallic band 3 features a first base layer 3a of an aluminum alloy. The second metallic band 4 features a second base layer 4a of a copper alloy and a tensile strength (Rm) > 360 MPa (tensile test according to DIN EN ISO 6892-1). The comparatively high tensile strength of the second metal strip 4 limits the joining process to welding – which, in the case of base metals other than metal strips 3 and 4, would lead to disadvantageous intermetallic phases. Such phases reduce the strength, ductility, and / or electrical conductivity of the welded joint, thereby reducing the stability of metal strip 1, for example, with respect to subsequent processability for forming a component, preferably by shaping, particularly deep drawing. This disadvantage is avoided according to the invention, by specially configuring the first metallic band 3, specifically by presenting a first and outer copper-plated layer 3b. This first plated layer 3b is located at least along a longitudinal edge 6a or longitudinal side of the first metallic band 3 and is provided there on the first base layer 3a. The first metallic band 3 is therefore structured on this longitudinal edge 6a with multiple layers, specifically with two layers, where one or more additional layers, for example one / more intermediate layers not shown, is / are conceivable, which has not been shown. In the embodiment shown in FIG. 1, the first plated layer 3b also forms a completely flat structure on the first base layer 3a, specifically on the flat side of the base layer 3a. The first metal strip 3 is thus plated on one side - where it is also conceivable that a base layer 3a is plated on both sides, which is not shown in the Figures. Firstly, by joining the first base layer 3a and the first plated layer 3b - despite their different base metals - harmful intermetallic phases between them can be avoided. However, the first plated layer 3b, in particular, opens the possibility of incorporating a second cross-section of band 2b in the metal band 1, made of a copper alloy with a tensile strength (Rm) > 360 MPa. This is achieved by extending the butt seam 5 essentially between the first plated layer 3b of the first cross-section of band 2a and the second cross-section of band 2b. This avoids disadvantageous intermetallic phases in the joint between the two cross-sections of band 2a and 2b. Furthermore, the production of the metal strip 1 is also considerably simplified by this first plated layer 3b. With this, the first metal strip and the second metal strip can be welded together continuously and in a butt joint 7 along the longitudinal side, with the second metal strip 4, which essentially connects to the first plated layer 3b by welding. In this way, a stable bond between the first metal strip 3 and the second metal strip 4 is achieved, as mixing of the base metals of other types of base materials 3a, 4b is minimal or even preventable. This is particularly true when this butt seam 5 is configured as an I-seam, as can be seen in FIG. 1, and the metal strips 3, 4 are welded using a radiation welding process with a laser. This can further facilitate the continuous production of the metal strip 1. As can be deduced from FIG. 1, the butt seam 5 extends exclusively between the first veneered layer 3b and the second base layer 4a. That coating 4b provided over the second base layer 4a and optional was separated before the bonding of materials in the joint surface area. This 4b coating can be, for example, a tin layer 2 to 10 µm thick. Other coatings are possible, such as a galvanic coating. It is also possible to weld the 4b coating together. A preferred combination of materials in metal band 1 is: First cross-section of band 2a or first metallic band 3: • first base layer 3a of Al 99.5 (EN AW-1050A) in the H14 or H24 state with an electrical conductivity of 34-36 MS / m. • first layer plated 3b of Cu-OF (material designation: EN CW008A) with a tensile strength (Rm) of 200 to 280 MPa. Second cross-section of band 2b or second metallic band 4: • second base layer 4a of CuNi3Si1 Mg with a tensile strength (Rm) of 620 to 760 MPa • eventual coating 4b, for example a zinc layer 4 µm thick. The metal strip 1, for example, has a thickness of 0.2 to 3.5 mm across all cross-sections of strip 2a and 2b, advantageously from 0.4 to 3 mm. Furthermore, a total strip width of 10 to 250 mm is conceivable for the metal strip 1, advantageously from 40 to 150 mm. The first metal band 3 has a first band thickness 8 greater than the second band thickness 9 of the second metal band 4. In the preferred material combination, there is a thickness ratio of the first band thickness 8 of the first cross-section of band 2a to the second band thickness 9 of the second cross-section of band 2b of 1 : 0.73 to 0.78. As can be deduced from the embodiment example, the first plated layer 3b has a tensile strength (Rm) < 420 MPa, which allows, for example, reproducible lamination plating on the first base layer 3a. As can also be seen in FIG. 1, a notch 10 in the form of a chamfer 10a can be seen on the longitudinal edge 6a or longitudinal side. This notch 10 is formed because the first base layer 3a is recessed relative to the first veneered layer 3b. The first metal strip 3 is therefore uneven or stepped on its longitudinal edge 6a. Preferably, this notch 10 is created by a separation process, for example, by chip removal, in the first base layer 3a, before the two metal strips 3, 4 meet for welding. The metal band 101 depicted in FIG. 2 according to a second embodiment is produced, in comparison with the metal band 101 of FIG. 1, from other metal bands 103 and 104. Thus, the first plated layer 3b is laid over the first base layer 3a, not as a completely flat layer, but in this embodiment example as a strip as a layer, specifically over the flat side of the base layer 3a, where the strip over the base layer 3a runs along this longitudinal edge 6a or longitudinal side. Furthermore, the second metallic band 104 exhibits a variation in thickness, and at its maximum thickness 9, it is greater than the thickness of layer 8a of the veneered layer 3b. Despite this, the second metallic band 104, specifically the second base layer 4a, connects exclusively with the first veneered layer 3b. This is also due to the fact that the first base layer 3a has a notch 10 in the form of a fold 10b, which extends into the first veneered layer 3b, specifically starting from it. Therefore, in this second embodiment as well, the first metallic band 3 has an uneven longitudinal edge 6a, or is stepped in shape. Intermetallic and, in most cases, brittle phases in the butt seam 5 cannot be produced in this way, which guarantees high stability in the metal strip 101. In addition, this bonding of materials can guarantee advantageous electrical properties, which is of significant importance, among other things, for electromobility. According to the third embodiment shown in FIG. 3, the metal strip 201 has three cross-sections, 2a, 2b, and 2c. The first cross-section, 2a, consists of a first metal strip 203 with a first plated layer 3b and a second plated layer 3c. The two plated layers 3b and 3c, identical in material and dimensions, are plated onto the first base layer 3a as a strip, specifically on the flat side of the base layer 3a. These strips run along one of the two parallel longitudinal edges 6a and 6b of the first metal strip 203. In this embodiment, the first metal strip 3 is flat on its longitudinal edge 6b and uneven or stepped on its longitudinal edge 6a. cccfrnn / eznz / E / YiAi In addition to the second metal band 4 joined by butt welding to the first plated layer 3b, which forms the second cross-section of band 2b, the metal band 201 still has a third metal band 205 which forms the third cross-section of band 2c. The third metal strip 205 is joined in the same way to the first metal strip 203, as is also the case with the second metal strip 4, or as is generally the case in all embodiments. The third metal strip 205, with the second base material 4a being the same as that of the second metal strip 4, is joined by butt welding 5 to the second plated layer 3c. The third metallic band 205 is thinner than the second metallic band 4 in band thickness 209 - however, a butt seam is also formed exclusively between the third metallic band 205 and the plated layer 3c, so that intermetallic and in most cases brittle phases cannot occur in the butt seam 5. This creates a stable metallic band 201. Metal strips 1, 101, and 201 of this type are therefore particularly suitable as a semi-finished product or starting material for an electrical contact, for example, a snap-fit ​​pin, etc. Metal strips 1, 101, and 201 are frequently referred to in the prior art, for example, as hybrid metal strips.

Claims

1Metallic band with a first cross-section (2a) of a first metallic band (3, 103, 203), having a first base layer (3a) of aluminum or an aluminum alloy, and with a second cross-section (2b) of a second metallic band (4, 104), the second metallic band (4, 104) having a tensile strength (Rm) > 360 MPa, in particular > 420 MPa, and a second base layer (4a) of copper or a copper alloy, wherein the first cross-section (2a) is bonded to the second cross-section (2b) by a butt seam (5) running along the length of the metallic band (1), characterized in that the first metallic band (3, 103, 203) has a first plated layer (3b) of copper or a copper alloy, provided at least along a longitudinal edge (6a,6b) over the first base layer (3a) and because the butt seam (5) extends essentially between the first plated layer (3b) of the first cross-section of band (2a) and the second cross-section of band (2b). 2.- Metallic band according to claim 1, characterized in that the first base layer (3a) has an electrical conductivity of at least 9 MS / m, in particular at least 18 MS / m.

3. - Metallic band according to claim 1 or 2, characterized in that the butt seam (5) extends exclusively between the first plated layer (3b) and the second cross-section of the band (2b), in particular the second base layer (4a). 4 - Metallic band according to claim 1, 2 or 3, characterized in that the first cross-section of band (2a) has a first band thickness (8) which is greater than or equal to the second band thickness (9) of the second cross-section of band (2b).

5. Metallic band according to claim 4, characterized in that there is a thickness ratio of the first band thickness (8) of the first cross-section of band (2a) with respect to the second band thickness (9) of the second cross-section of band (2b) of 1:1 to 1:0.2, in particular from 1:0.6 to 1:0.

7.

6. Metallic band according to any one of claims 1 to 5, characterized in that the second base layer (4a) is made of a curable copper alloy, in particular it has a CuNiSi base, for example it is made of a CuNi1,5Si alloy, CuNi3Si 1 Mg alloy or CuNi2SiSn alloy, or it is made of a lean copper alloy, in particular CuFe2P alloy, or a Cu-Sn alloy, in particular CuSn6 alloy.

7. - Metallic band according to any one of claims 1 to 6, characterized in that the first plated layer (3b) has a tensile strength (Rm) < 420 MPa, in particular < 360 MPa.

8. - Metallic band according to any one of claims 1 to 7, characterized in that the first plated layer (3b) is made of copper, in particular with the designation of material EN CW008A, or of a lean copper alloy or of a Cu-Sn alloy.

9. - Metal band according to any one of claims 1 to 8, characterized in that the first cross-section of the band (2a) has a notch (10) entering with respect to the plated layer (3b) on the longitudinal edge (6a), in particular a chamfer (10a) or a fold (10b).

10. - Metal band according to any one of claims 1 to 9, characterized in that the first plated layer (3b) and the first base layer (3a) are plated by lamination and / or in that the butt seam (5) is configured as an I-seam. 11 Semi-finished product or starting material of a metal strip (1,101,201) according to one of claims 1 to 10 for at least one electrical construction piece, in particular an electrical contact.

12. - Method for the continuous production of a metal strip (1, 101, 201) according to any one of claims 1 to 10, wherein the first metal strip (3, 103, 203) with the first base layer (3a) being made of aluminum or an aluminum alloy and with the first plated layer (3b) of copper or a copper alloy, wherein the first plated layer (3b) is provided at least along the longitudinal edge (6a, 6b) of the first metal strip (3, 103, 203) on the first base layer (3a), and the second metal strip (4, 104) having a tensile strength (Rm) > 360 MPa, in particular > 420 MPa, and with the second base layer (4a) being made of copper or a copper alloy, are continuously welded together along the longitudinal side. and joined together, the second metal band (4, 104), which essentially connects to the first plated layer (3b) by welding, to this first plated layer (3b).

13. - Method according to claim 12, characterized in that the second metal band (4, 104), in particular the second base layer (4a), connects butt-to-butt exclusively with the first plated layer (3b). 14.- Method according to claim 12 or 13, characterized in that the first metal strip (3, 103, 203) and the second metal strip (4, 104) are welded together using a radiation welding process, preferably using a laser.

15. - Method according to one of claims 12 to 14, characterized in that the first plated layer (3b) and the first base layer (3a) are plated by lamination.

16. - Method according to any one of claims 12 to 15, characterized in that before welding the first metal strip (3, 103, 203) is provided with a notch (10) entering with respect to the first plated layer (3b) on the longitudinal edge (6a), in particular a chamfer (10a) or a fold (10b).

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