Method for producing an overlap composite material from sheet metal

Abstract

A method for producing an overlap composite material from sheet metal is described, wherein a first sheet of a first metal and a second sheet of a second metal, which has a lower strength than the first metal, are positioned one above another in an overlapping manner in an edge region, and are then joined by rolling. The first sheet has a wedge-shaped edge in cross-section. The second sheet is to be positioned with its edge on a side surface of the first sheet formed by the wedge-shaped edge. The side surface formed by the wedge-shaped edge of the first sheet has a greater width than the side surface of the edge of the second sheet positioned on the said side surface of the first sheet, and, after positioning, the sheets are joined by rolling.

Claims

1. A method for producing an overlap composite material from sheet metal, the method comprising the steps of: providing a first sheet made of a first metal and a second sheet made of a second metal which has a lower strength than the first metal; positioning the sheets on top of one another in an overlapping manner in an edge region; and joining the sheets by rolling; wherein the first sheet has, in cross-section, a wedge-shaped edge; wherein the second sheet, with its edge region, is positioned on an inclined side surface of the first sheet formed by the wedge-shaped edge; wherein the inclined side surface of the first sheet is convex and free of hollows or indentations, the inclined side surface extending continuously from a front face to a rear face of the first sheet; wherein, before joining the sheets by rolling, the inclined side surface of the first sheet has a first width corresponding to a distance measured extending parallel to the first sheet between an edge on a front face of the first sheet to an adjacent edge on a rear face of the first sheet; wherein the edge region of the second sheet that is positioned on the inclined side surface of the first sheet forms a side edge that extends continuously from a front face of the second sheet to a rear face of the second sheet and has a second width to be measured from the front face of the second sheet to the rear face of the second sheet; and wherein the first width is at least twice as large as the second width and the edge region of the second sheet is not wedge-shaped or inclined.

2. The method according to claim 1, wherein the wedge-shaped edge has a main section, which constitutes the major part of the length of the wedge-shaped edge region, and an end section, wherein the thickness in the main section decreases more slowly per unit length than in the end section.

3. The method according to claim 2, wherein the end section has a length that is between one fifth and one twentieth of a length of the main section.

4. The method according to claim 2, wherein in cross section, a surface of the main section encloses an angle of not more than 30° with a plane of the first sheet, the plane of the first sheet extending along a thickness of the first sheet.

5. The method according to claim 4, wherein a surface of the end section with the plane of the first sheet encloses an angle from 55° to 80°.

6. The method according to claim 1, wherein the inclined side surface formed by the wedge-shaped edge of the first sheet has the length that is at least twice that of the thickness of the side edge of the second sheet that is positioned on the said inclined side surface of the first sheet.

7. The method according to claim 1, wherein the side edge of the second sheet is positioned on the wedge-shaped edge of the first sheet at a location at which the wedge-shaped edge has a thickness that is at least half a maximum thickness of the first sheet.

8. The method according to claim 1, wherein, after joining the sheets by rolling, the wedge-shaped edge of the first sheet extends continuously from a front face to a rear face of the second sheet.

9. The method according to claim 1, wherein the first sheet is made of copper or a copper-based alloy.

10. The method according to claim 1, wherein the second sheet is made of aluminium or an aluminium-based alloy.

11. The method according to claim 1, wherein the overlap composite material has a thickness that is between 60% and 30% of a maximum thickness of the first sheet before rolling.

12. A method for producing an overlap composite material from sheet metal, the method comprising the steps of: providing a first sheet made of a first metal and a second sheet made of a second metal which has a lower strength than the first metal; positioning the sheets on top of one another in an overlapping manner in an edge region; and joining the sheets by rolling; wherein the first sheet has a thickness and a wedge-shaped edge region, said thickness decreasing in the wedge-shaped edge region; wherein the second sheet, with its edge region, is positioned on an inclined side surface of the first sheet formed by the wedge-shaped edge region; wherein the inclined side surface of the first sheet is convex and free of hollows or indentations, the inclined side surface extending continuously from a front face to a rear face of the first sheet; wherein, before joining the sheets by rolling, the edge region of the second sheet is not wedge-shaped or inclined.

13. The method according to claim 12, wherein, before joining the sheets by rolling, the edge of a side surface of the second sheet is not similarly shaped as the wedge-shaped edge of the first sheet.

14. A method for producing an overlap composite material from sheet metal, the method comprising the steps of: providing a first sheet made of a first metal and a second sheet made of a second metal which has a lower strength than the first metal; positioning the sheets on top of one another in an overlapping manner at their respective edge regions; and joining the sheets by rolling; wherein the first sheet has a thickness and a wedge-shaped edge region, said thickness decreasing in the wedge-shaped edge region; wherein the first sheet has an inclined side surface formed by the wedge-shaped edge region, said inclined side surface being convex and free of hollows or indentations, the inclined side surface extending continuously from a front face to a rear face of the first sheet, wherein the second sheet, with its edge region, is positioned on the inclined side surface of the first sheet, wherein, before joining the sheets by rolling, the second sheet has in its edge region that is positioned on the inclined side surface of the first sheet a side edge that extends continuously at only right angles from a front face of the second sheet to a rear face of the second sheet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the invention are explained in an example of embodiment of the invention, with reference to the accompanying figures.

(2) Here:

(3) FIG. 1 shows a schematic representation of metal sheets for the production of an overlap composite material;

(4) FIG. 2 shows the sheets shown in FIG. 1 before rolling;

(5) FIG. 3 shows a detail from FIG. 1;

(6) FIG. 4 shows a cross-sectional view of the overlapping composite material; and

(7) FIG. 5 shows a detail from FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) FIG. 1 shows two first sheets 1, made, for example, of copper or a copper-based alloy, and a second sheet 2, from which the overlap composite material shown in FIG. 4 is made. In the example shown, the first sheets 1 and the second sheet 2 have the same thickness within the production tolerance. Sheets 1 and 2 can, however, also be of different thicknesses, for example, they can have thicknesses that differ from one another by 20%.

(9) One of the first sheets 1 of FIG. 1 is shown in detail in FIG. 3. The first sheet 1 has a wedge-shaped edge of width bF1. This wedge-shaped edge forms an inclined side surface 3, against which the second sheet 2 is positioned with its edge, as shown in FIG. 2. The width of the side surface 3 of the first sheet 1 is greater than the width of the corresponding side surface 4. In the example shown, the width of the side surface 3 is more than twice the width of the side surface 4.

(10) The width bF1 of the wedge-shaped edge region and the width of the side surface 3 measured as the arc length are more than twice the thickness of the first sheet 1. The width of the wedge-shaped edge measured from the tip of the wedge can also be considerably more than twice the thickness of the sheet. However, a width of more than 4 times the sheet thickness usually has no advantages.

(11) In the sectional view of FIG. 3, the wedge-shaped edge region has a blunted tip. In other words, the thickness of sheet 1 in the wedge-shaped edge region decreases faster in an end section adjacent to the tip than in a main section, which accounts for most of the width of the wedge-shaped edge region.

(12) The side surface 3 can be convex, in other words free of hollows or indentations. In the example shown the reduction of the thickness of the first sheet 1 in the wedge-shaped edge region is strictly monotonic.

(13) In the design example shown, the side surface in the main section is a plane that subtends an angle α1 with the plane of the sheet metal, which can be between 10° and 30°, in particular between 15° and 25°, for example, and in FIG. 3 is approximately 20°. In the end section, the side surface is more inclined, e.g. firstly with an angle β1 and then with an angle γ1. The angle β1 can, for example, be between 25° and 50°, preferably between 35° and 45°, and in the example shown is 40°. The angle γ1 is greater than the angle β1, for example between 45° and 80°, in particular between 55° and 65°, and in the example shown is 60°.

(14) In the example shown, the side surface 3 is formed by planar sub-surfaces. The side surface 3 can, however, also be curved in design. More generally, the shape of the side surface can therefore be described such that, as seen in cross-section, each tangent to the side surface 3 in the main section with the plane of the sheet metal subtends an angle of at most 30°, preferably at most 20°, while each tangent in the end section with the plane of the sheet metal subtends an angle of at least 30°, preferably at least 35°, for example 40° or more. The angle that a tangent subtends on the end section with the plane of the sheet increases towards the tip, for example to values of 50° or more. For example, in a first part of the end section, each tangent with the plane of the sheet can subtend an angle of less than 50°, e.g. 35° to 45°, and the thickness can decrease from a value hβ1 to a value hγ1. From this thickness on, each tangent subtends an angle with the plane of the sheet of more than 50°, for example 55° to 80°. For example, the value hβ1 can be 10% to 40%, in particular 20% to 30%, of the maximum thickness of the first sheet 1, the value hγ1 can be 5% to 15%, in particular 5% to 10%.

(15) The main section can be directly adjacent to the end section. However, there can also be a transition section between the main section and the end section.

(16) In the main section, the thickness of the edge section is reduced by three fifths or more, for example by 60% to 90%, in particular by 70% to 80%. The main section has a width that is at least as large as the maximum thickness of the first sheet 1. The main section preferably has a width that is at least 1.5 times the maximum thickness of the first sheet 1. The end section has a width that is, for example, between one fifth and one seventh of that of the main section.

(17) As FIGS. 1 and 2 show, the side surface 3 formed by the wedge-shaped edge of the first sheet 1 is at least twice as wide as the side surface 4 of the edge of the second sheet 2, which is positioned against this side surface 3 of the first sheet 1. The side surface 4 is inclined. The second sheet 2 tapers as from the point at which it is positioned against the first sheet 1. In other words, the second sheet 2 has an edge which, seen in cross-section, tapers from the edge that is positioned on the wedge-shaped edge of the first sheet 1. For example, the edge can, as seen in cross-section, taper over a length hβ1, to be measured in the plane of the sheet, which is not more than a quarter of the maximum thickness of the second sheet, preferably over a length that is between a fifth and a twentieth of the maximum thickness of the second sheet. The edge region of the second sheet 2 is therefore narrow, and the thickness of the second sheet 2 reduces to zero over a width that is between one fifth and one twentieth of the thickness of the sheet 2.

(18) The side surface 4 can be a flat surface that subtends an angle α2 of 80° to 89° with the plane of the sheet, e.g. 86° to 89°. The side surface 4 can, however, also be curved.

(19) FIG. 2 shows how the sheets 1, 2 are positioned together. The second sheet 2 is positioned on the wedge-shaped edge of the first sheet 1, preferably at a point at which the edge 4 has a thickness h02 that is more than half the maximum thickness h01 of the first sheet 1, for example between 70% and 90%. In FIG. 2, the second sheet 2 touches the side surface 3 of the first sheet 1 at a point where the thickness of sheet 1 is between 85% and 90% of the maximum thickness h01 of the first sheet 1.

(20) After the sheets 1, 2 have been laid against one another as shown in FIG. 2, they are joined together by rolling to form the overlapping composite material shown in FIG. 4. Sheets 1, 2 are thereby strongly deformed, so that the composite material has a thickness h1 that is typically not more than three fifths of the maximum thickness of the first sheet 1 before rolling. In the example shown, the composite material has a thickness h1 that is less than 40% of the original thickness of the first sheet 1.

(21) During rolling, the edge region of the second sheet 2 is deformed particularly strongly so that it adapts to the contour of the edge region of the first sheet 1. FIG. 5 shows schematically the connection zone between the first sheet 1 and the second sheet 2 of the finished overlapping composite material.

(22) Before the execution of the described method, the sheets 1, 2 are degreased and cleaned. The sheets 1, 2 can then be annealed so as to adjust to a defined material state, especially for the more solid material. Alternatively or additionally, the sheets 1, 2 can also be brushed before the execution of the method.