Method for forming a moulding and moulding

Abstract

A shaped part and a method for forming the shaped part from a lightweight metal or alloy by extrusion of a slug performed along a pressing axis. The shaped part is formed in at least one region with a deviation from a basic form that is rotationally symmetrical with respect to the pressing axis. The symmetry-deviating region extends over a wall portion of the shaped part that is formed by backward cup extrusion with a normal vector extending predominantly orthogonally in relation to the pressing axis. The same extruding operation forms a structure that surrounds the pressing axis, on a sheet-like base of the shaped part that adjoins the wall portion and has a normal vector extending predominantly in the direction of the pressing axis on the side thereof opposite from the wall portion. In a region of lowest wall thickness of the wall portion at the transition to the base, the quotient of this wall thickness in mm and an average curvature (1/r) in mm.sup.−1, formed at the transition, is greater than 0.03 and/or, in an at least predominant region of the base-wall transition when seen in the circumferential direction, the ratio of the wall thickness to the base thickness is less than 1.0.

Claims

1. A method for forming a moulding from a light metal or a light metal alloy by impact extrusion of a slug carried out along a press axis, wherein the moulding is formed with a deviation from a rotationally symmetrical basic form with reference to the press axis by having a wall structure with a polygonal contour running around the press axis, said wall structure of the moulding being formed by indirect cup extrusion and having a normal vector running predominantly orthogonally to the press axis, and in the same impact extrusion process a surrounding structure running around the press axis is formed by direct cup extrusion, direct hollow extrusion or direct solid extrusion on an areal base of the moulding adjacent to the wall section, said areal base having a normal vector running predominantly in the direction of the press axis, said surrounding structure being on the side of the areal base side opposite the wall section, wherein in an area of smallest wall thickness of the wall section at the transition to the base a quotient of the wall thickness in divided by an average curvature in formed at the transition is greater than 0.03 and/or, seen in the circumferential direction, in an at least predominant area of the base-wall transition the ratio of wall thickness to base thickness is less than 1.0, wherein at least one pin is formed by solid extrusion on the areal base decentralized from a middle of the areal base.

2. The method according to claim 1, wherein the quotient is greater than 1/10000 of the surface of the base area measured in mm.sup.2.

3. The method according to claim 1, wherein the basic form of the areal base and/or the contour of the wall structure is/are symmetrical with reference to at least one axis of symmetry.

4. The method according to claim 1, wherein a contour form of the slug matches a contour of the areal base.

5. The method according to claim 1, wherein over at least 80% of the circumference a wall thickness of the wall structure has less than 8% relative deviation from each other and/or, seen over the circumference, a maximum wall thickness divided by a minimum wall thickness is less than 3.6.

6. The method according to claim 1, wherein a forming tool closed on one side is used.

7. The method according to claim 1, wherein the slug and/or working surfaces of an impact extrusion press carrying out said impact extrusion are provided with lubricant.

8. The method according to claim 1, wherein several of the same type of these mouldings are produced at intervals of less than 2 s.

9. The method according to claim 1, wherein, seen in the direction of the press axis, the wall structure and the surrounding structure are aligned with each other.

10. The method according to claim 1, wherein subsequent processing of the moulding is carried out following the impact extrusion.

11. A method for producing a combination component formed from two mouldings, consisting of the same light metal or the same light metal alloy, in which a first moulding is formed according to the method in claim 1 and a second moulding deviating from the first moulding, and in which the first and second moulding are designed for connecting to each other, arranged one behind the other in the direction of the press axis.

12. The method according to claim 11, wherein the relevant connecting area is made weldable.

13. The method according to claim 10, wherein in the connected state the first and second moulding delimit a cavity and, apart from access points provided, the cavity is sealed tight.

14. An impact extruded moulding made of a light metal or a light metal alloy, wherein the moulding is formed with a deviation from a rotationally symmetrical basic form with reference to a press axis by having a wall structure with a polygonal contour around the press axis, said wall structure of the moulding being formed by indirect cup extrusion and having a normal vector running predominantly orthogonally to the press axis, and in the same impact extrusion process a surrounding structure running around the press axis is formed by direct cup extrusion, direct hollow extrusion or direct solid extrusion on an areal base of the moulding adjacent to the wall section, said areal base having a normal vector running predominantly in the direction of the press axis, said surrounding structure being on the side of the areal base opposite the wall section, wherein in an area of smallest wall thickness of the wall structure at the transition to the base a quotient of the wall thickness in mm divided by an average curvature in mm.sup.−1 formed at the transition is greater than 0.03 and/or, seen in the circumferential direction, in an at least predominant area of the base-wall transition the ratio of wall thickness to base thickness is less than 1.0, wherein at least one pin is formed by solid extrusion on the areal base decentralized from a middle of the areal base.

15. The moulding according to claim 14, comprising further form characteristics.

16. A combination component, formed from two mouldings, which consist of the same light metal or the same light metal alloy, in which a first moulding is formed according to claim 14 and a second moulding deviates in form from the first moulding, in which the first and second moulding are designed for connecting to each other, arranged one behind the other in the direction of the press axis.

17. The method according to claim 1, wherein the quotient is greater than 0.1.

18. The method according to claim 17, wherein the quotient is greater than 0.3.

19. The method according to claim 18, wherein the quotient is greater than 0.6.

20. The method according to claim 1, wherein the ratio of wall thickness to base thickness is less than 0.85.

21. The method according to claim 20, wherein the ratio of wall thickness to base thickness is less than 0.7.

22. The method according to claim 2, wherein the quotient is greater than 1/4000 of the surface of the base area.

23. The method according to claim 22, wherein the quotient is greater than 1/1000 of the surface of the base area.

24. The method according to claim 3, wherein the basic form of the areal base and/or the contour of the wall structure is/are symmetrical with reference to at least two axes of symmetry.

25. The method according to claim 24, wherein the basic form of the areal base and/or the contour of the wall structure is/are symmetrical with reference to at least four axes of symmetry.

26. The method according to claim 5, wherein over the at least 80% of the circumference the wall thickness of the wall structure has less than 4% relative deviation from each other.

27. The method according to claim 26, wherein over the at least 80% of the circumference the wall thickness of the wall structure has less than 2% relative deviation from each other.

28. The method according to claim 5, wherein, seen over the circumference, the maximum wall thickness divided by the minimum wall thickness is 3.2.

29. The method according to claim 28, wherein, seen over the circumference, the maximum wall thickness divided by the minimum wall thickness is 2.8.

30. The method according to claim 6, wherein the forming tool is closed on two sides.

31. The method according to claim 8, in which several of the same type of these mouldings are produced at intervals of less than 1.3 s.

32. The method according to claim 31, in which several of the same type of these mouldings are produced at intervals of less than 0.7 s.

33. The method according to claim 10, wherein the subsequent processing is milling and/or drilling.

34. The method according to claim 11, wherein the second moulding deviates in form from the first moulding.

35. The method according to claim 13, wherein the cavity is sealed gas tight.

36. The moulding according to claim 14, wherein the quotient is greater than 0.1.

37. The moulding according to claim 36, wherein the quotient is greater than 0.3.

38. The moulding according to claim 37, wherein the quotient is greater than 0.6.

39. The moulding according to claim 14, wherein the ratio of wall thickness to base thickness is less than 0.85.

40. The moulding according to claim 39, wherein the ratio of wall thickness to base thickness is less than 0.7.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Further characteristics, details and advantages of the invention result from the following description with reference to the enclosed figures, in which

(2) FIG. 1 shows a moulding produced by extrusion diagrammatically,

(3) FIG. 2 shows a diagrammatic illustration of a part of an axial section through the moulding shown in FIG. 1 and

(4) FIG. 3 shows a transition area between a wall section and a base of a moulding, and

(5) FIG. 4 schematically shows a combination component formed from two mouldings with a cavity therebetween.

DETAILED DESCRIPTION OF THE INVENTION

(6) In FIG. 1 a moulding 10, which was produced by extrusion, is shown in a perspective diagrammatic view. About halfway up in the direction of the press axis a base 5 may be seen, which has a polygonal form, here the form of a pentagon, and it is also described as a floor in the following. However, other forms instead of the pentagonal form could also be used, particularly those that have axes of symmetry.

(7) The structure that is above the floor 5 in FIG. 1 is formed by indirect cup extrusion and has a wall section 6.1, as well as further wall sections 6.2, 6.3, 6.4 and 6.5 in this embodiment, which together form an upper wall structure 6.

(8) The arrangement formed below the floor 5 in FIG. 1 is a surrounding structure 7, which in this example embodiment corresponds to the wall structure 6 in its form. In the embodiment illustrated the floor 5 is about halfway up the moulding 10, but its position could also be asymmetric, therefore higher or lower than illustrated in FIG. 1.

(9) A pin part 8, which is formed by indirect solid extrusion, extends decentralised from the floor 5 in an upward direction. The pin 8, as well as further pins that may be provided if necessary, are an example of the design of a structure within the cavity enclosed by the wall structure 6.

(10) Not illustrated in FIG. 1 is a relative, though also small difference in height on the top edge 9, that is to say a small earring formation in the form of a higher wall height in the middle of the relevant wall section 6.1, which exists immediately after extrusion. Rather the top edge 9 is illustrated at the same height, produced by a milling process carried out after the extrusion process for example. Naturally further structures may be incorporated into the moulding shown in FIG. 1 by subsequent milling or drilling processing, such as grooves, holes, steps and through holes for instance. The surface on the underside of the floor 5 in this embodiment is made flat according to a preferred embodiment and, apart from the surrounding wall structure, represents a flat surface.

(11) It may be seen that in the viewing direction of the extrusion press axis the wall structure 6 and the surrounding structure 7 are aligned with each other. Therefore the moulding shown in FIG. 1 is suitable for being fitted together with a similar moulding into a combination component. For this a welded connection may be produced permanently between (in the case of identical components) the top edge 9 of a first component and the bottom edge of the other component for example. Therefore the container interior formed through this may also be sealed tight, particularly gas tight.

(12) In the view in FIG. 2, in which a curve provided in the transition area between the floor 5 and wall section 6.1 or the surrounding structure 7 is not illustrated in any case, it may be seen that the wall thickness w is selected smaller than the floor thickness b. When extruding the moulding this results in a more uniformly directed flow of the material and great homogeneity of the wall structure 6 and also the surrounding structure 7 due to this.

(13) In FIG. 3 the transition from floor 8 to wall section 6.1 is represented again diagrammatically with a curve and its radius of curvature r. The ratio from the wall thickness w in [mm], here 2, and the average curvature 1/r in [mm.sup.−1] formed at the transition, here 1/0.35, is 0.7 in the example illustrated.

(14) The invention is not limited to the embodiment shown in the example explained above. Rather the characteristics of the following claims as well as the above description may be essential for the invention in its various embodiments.