Connecting element, in particular screw or nut

Abstract

The invention relates to a connecting element (4, 5), in particular a screw (4) or a nut (5), for mechanically connecting components (1, 2), the connecting element (4, 5) consisting at least partially of a material with a mechanical tensile strength of at least 350 MPa. According to the invention, the material of the connecting element (4, 4, 5, 8) has an electrical conductivity of at least 50% IACS. The invention also relates to a corresponding production method for a connecting element (4, 5) of this type.

Claims

1. A connecting element for mechanically connecting components, wherein the connecting element comprises a material with a mechanical tensile strength of at least 350 MPa, wherein the material of the connecting element is a copper/chromium alloy having a mass percentage of chromium of 0.2%-1% and an electrical conductivity of at least 50% IACS, and the connecting element is one of a nut, a rivet and a bolt.

2. The connecting element according to claim 1, wherein a) the mechanical tensile strength of the material of the connecting element is at least 400 MPa, and b) the electrical conductivity of the material of the connecting element is at least 60% IACS.

3. The connecting element according to claim 2, wherein c) the material of the connecting element has a yield strength of at least 100 MPa, and d) the material of the connecting element has an elongation at break of at least 1%.

4. The connecting element according to claim 1, having a mass percentage of up to 0.2% of at least one of the following materials; silver, magnesium, hafnium, titanium, zirconium and tin.

5. The connecting element according to claim 3, wherein the material of the connecting element is a copper/magnesium alloy.

6. The connecting element according to claim 5 having a mass percentage of magnesium of 0.1%-0.5%.

7. The connecting element according to claim 3, wherein the material of the connecting element is a copper/niobium alloy.

8. The connecting element according to claim 7 with a copper sheath.

9. The connecting element according to claim 3, wherein the material of the connecting element is a copper/nickel/silicon alloy.

10. The connecting element according to claim 9, wherein the material of the connecting element is CuNi.sub.3Si.

11. The connecting element according to claim 1, further comprising a covering made of copper.

12. The connecting element according to claim 1, further comprising a formed-on disc on the connecting element, the disc increasing a contact surface by at least 50%.

13. A current conductor arrangement with a) a first current-conducting component, b) a second current-conducting component, and c) a connecting element according to claim 1 which connects the first current-conducting component to the second current-conducting component.

14. The current conductor arrangement according to claim 13, wherein at least one of the first current-conducting component and the second current-conducting component is a conductor bar.

15. The current conductor arrangement according to claim 13, wherein at least one of the first current-conducting component and the second current-conducting component is a member selected from the group consisting of: a) a cable lug, b) an automotive body sheet, c) a hull of a boat, d) a conductor bar, e) a resistor, and f) a mass point.

16. A production method for producing the connecting element according to claim 1.

17. The production method according to claim 16, further comprising the following steps: a) producing a rolled wire from a material, b) solution heat treatment of the rolled wire, c) drawing the rolled wire to a specified nominal diameter.

18. The production method according to claim 17, further comprising removing an oxide layer on the rolled wire after the solution heat treatment of the rolled wire and prior to the drawing of the rolled wire.

19. The production method according to claim 17, wherein the production of the rolled wire comprises the following steps: a) melting the material in a vacuum furnace and then b) hot-rolling the material to form the rolled wire.

20. The production method according to one of claim 17, wherein the solution heat treatment of the rolled wire comprises the following steps: a) heating the rolled wire, and b) quenching the rolled wire.

21. The production method according to claim 20, wherein the rolled wire is heated to a temperature of +800-1200 C. for a duration of 5-15 minutes before quenching.

22. The production method according to claim 17, further comprising the following sequential steps: a) precipitation hardening the rolled wire, and b) forming connecting elements from the precipitation-hardened rolled wire.

23. The production method according to claim 22, wherein the precipitation hardening takes place at a temperature of +300-600 C. for a period of 4-16 hours.

24. The production method according to claim 22, wherein the precipitation hardening of the rolled wire takes place after the solution heat treatment and after the removal of the oxide layer.

25. The production method according to claim 22, wherein the precipitation hardening of the rolled wire takes place after the solution heat treatment and prior to the removal of the oxide layer.

26. The production method according to claim 17, further comprising the following sequential steps: a) forming connecting elements from the rolled wire prior to the precipitation hardening, and b) precipitation hardening the formed connecting elements.

27. The production method according to claim 26, wherein the precipitation hardening takes place at a temperature of +300-600 C. for a period of 4-16 hours.

28. The production method according to claim 16, further comprising the following steps: a) making available a copper/magnesium alloy, b) first cold forming of the copper/magnesium alloy to form a semi-finished product, and c) cold forming of the copper/magnesium alloy to form connecting elements.

29. The production method according to claim 28, wherein the copper/magnesium alloy comprises a mass percentage of magnesium of 0.1%-0.5%.

30. The production method according to claim 16, further comprising the following steps: a) making available a composite material made from a copper/niobium alloy with a copper sheath, b) drawing the composite material, and c) forming connecting elements from the composite material.

31. The production method according to claim 30, wherein the copper/niobium alloy comprises a mass percentage of niobium of 5%-30%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantageous developments of the invention will be explained in greater detail below with reference to the figures together with the description of the preferred examples of embodiment of the invention. Therein:

(2) FIG. 1 is a schematic cross-sectional view through a conductor-bar arrangement according to the invention,

(3) FIG. 2 is a schematic cross-sectional view of a screw according to the invention with a formed-on disc,

(4) FIG. 3 is a variant of the production method according to the invention as a flow chart with a copper/chromium alloy as starting material,

(5) FIG. 4 is a modification of FIG. 3,

(6) FIG. 5 is a further modification of FIG. 3,

(7) FIG. 6 is another variant of the invention with a copper/magnesium alloy as starting material,

(8) FIG. 7A is a further variant of a production method according to the invention with a copper/niobium alloy as starting material,

(9) FIG. 7B is a schematic cross-sectional view through a connecting element produced according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(10) FIG. 1 shows a schematic representation of a conductor-bar arrangement according to the invention with two conductor bars 1, 2 made of copper, the two conductor bars 1, 2 lying with their free ends in plan-parallel manner one on another and being electrically and mechanically connected together by a screw connection 3.

(11) The screw connection 3 in this case consists of a screw 4 according to the invention with a correspondingly adapted nut 5.

(12) The screw 4 and the nut 5 in this case consist of a special material which combines a high mechanical tensile strength of at least 350 MPa with a high electrical conductivity of at least 50% IACS. With regard to the concrete composition of the material of the screw 4 and the nut 5, there are various possibilities, some variants of which will be described in detail below.

(13) FIG. 2 shows a modification of a screw 4 with a screw head 6 with a formed-on disc 7, the disc 7 increasing the contact surface of the screw head 6 by more than 100%. This is advantageous in particular whenas in FIG. 1relatively soft components made of copper are to be connected together.

(14) Below, now first of all the flow chart in FIG. 3 is described, which describes a first variant for producing the material for the connecting element according to the invention.

(15) In a first step S1, first of all a rolled wire is produced.

(16) To this end, first of all in a step S1.1 a suitable material (e.g. a copper/chromium alloy) is melted in a vacuum furnace. Then the material is subsequently rolled in a step S1.2 to produce the desired rolled wire with a diameter of d=8-12 mm.

(17) In a subsequent step S2, solution heat treatment of the rolled wire then takes place. In the context of the solution heat treatment, the rolled wire is first of all heated to a temperature of T1=+1000 C. in a step S2.1 for a period t1=10 minutes. Then the heated rolled wire is subsequently quenched in water in a step S2.2.

(18) In a further step S3, then the oxide layer on the rolled wire is removed in a shaving line. In this case, the oxide layer on the rolled wire is mechanically shaved off the wire with an annular, sharp tool, the internal diameter of the tool being less than the external diameter of the rolled wire.

(19) In a step S4, the rolled wire is then drawn to the desired nominal diameter in conventional manner.

(20) Subsequently, in a step S5 precipitation hardening of the rolled wire in a box annealing furnace takes place at a temperature of T2=+400-450 C. for a period t2=6-10 hours.

(21) After these steps, the material has then attained a tensile strength of around 400 MPa, an elongation at break of 10% and an electrical conductivity of more than 85% IACS.

(22) In a further step S6, a screw is then formed from the rolled wire.

(23) The example of embodiment according to FIG. 4 largely corresponds to the example of embodiment described above and illustrated in FIG. 3, so reference is made to the above description of FIG. 3 in order to avoid repetition.

(24) One distinctive feature of this example of embodiment consists in that the precipitation hardening of the rolled wire is moved from step S5 in FIG. 3 into step S3 in FIG. 4. The precipitation hardening of the rolled wire in this case therefore takes place chronologically prior to the removal of the oxide layer in a shaving line and also prior to the drawing of the rolled wire.

(25) The example of embodiment according to FIG. 5 likewise largely corresponds to the example of embodiment according to FIG. 3, so reference is made to the above description of FIG. 3 in order to avoid repetition.

(26) One distinctive feature of this example of embodiment consists in switching steps S5 and S6 in FIG. 3. This means that first of all in a step S5 the individual screws are formed from the rolled wire and subsequently then the formed screws are precipitation-hardened as piece goods in a step S6.

(27) The example of embodiment according to FIG. 6 will now be described below.

(28) In this case, first of all in a step S1 a copper/magnesium alloy is made available. Solid-solution hardening is achieved by the alloying. Thereupon, screws are then produced from the hardened copper/magnesium alloy by cold forming in a step S2.

(29) Below, the example of embodiment according to FIG. 7A will now be described with reference to FIGS. 7A and 7B.

(30) In this case, first of all in a step S1 a composite material consisting of a copper/niobium alloy with a copper sheath is made available.

(31) FIG. 7B shows a schematic cross-sectional view through a screw 8 with a core 9 of the copper/niobium alloy and a sheath 10 of copper, the sheath 10 of copper providing the desired electrical conductivity.

(32) In a step S2, the composite material is then drawn, and in a step S3 screws are formed therefrom.

(33) The invention is not limited to the preferred examples of embodiment described above. Rather, a large number of variants and modifications are possible which likewise make use of the inventive concept and therefore fall within the extent of protection. In particular, the invention also claims protection for the subject-matter and the features of the dependent claims independently of the claims referred to.

(34) List of Reference Numerals:

(35) 1 conductor bar

(36) 2 conductor bar

(37) 3 screw connection

(38) 4 screw

(39) 4 screw

(40) 5 nut

(41) 6 screw head

(42) 7 disc

(43) 8 screw

(44) 9 core of screw 8

(45) 10 sheath of screw 8