Portal Axle for a Rail Vehicle and Method for Manufacturing a Portal Axle of This Type

Abstract

A portal axle as well as a method for manufacturing a portal axle for a rail vehicle, which has an axle centre part extending along a longitudinal axis and two kingpins one of which sits on a first end section of the axle centre part and a second on a second end section of the axle centre part formed opposite to the first end section. The kingpins are oriented away from the axle centre part and form an axis of rotation in use for a rail wheel rotatably mounted on the respective kingpin. The portal axle has optimised usage properties with minimised weight. This is achieved by a longitudinal opening extending in the longitudinal direction of the portal axle being formed in at least one of the mould components. The invention further provides a method for manufacturing an axle of this type.

Claims

1-14. (canceled)

15. A portal axle for a rail vehicle, with the following moulded components: an axle centre part extending along a longitudinal axis, and two kingpins, one of which sits on a first end section of the axle centre part and a second on a second end section of the axle centre part formed opposite to the first end section, wherein the kingpins are oriented away from the axle centre part and form an axis of rotation in use for a rail wheel rotatably mounted on the respective kingpin, wherein the axle centre part has an upper side assigned to a body of the rail vehicle in use and wherein the kingpins are positioned on the upper side of the axle centre part and wherein a longitudinal opening extending in the longitudinal direction of the portal axle is formed in at least one of the mould components, characterized in that at least one longitudinal opening is moulded into the mould components and in that the longitudinal opening is designed as a through-opening that passes through the respective mould component.

16. The portal axle according to claim 15, wherein the kingpins each have a longitudinal opening formed as a through-opening and in that the longitudinal opening has a first section extending in the longitudinal direction of the longitudinal opening and a second section extending up to the free end face of the kingpin originating from its outlet assigned to the axle centre part, the diameter of which is smaller than the diameter of the first section.

17. The portal axle according to claim 15, wherein at least two longitudinal openings are moulded into the axle centre part.

18. The portal axle according to claim 15, wherein it is manufactured from a steel material with its moulded components in one piece.

19. The portal axle according to claim 18, wherein the longitudinal opening is treated with corrosion protection at least on its inner surface.

20. The portal axle according to either claim 18, wherein it has a hardness at least in the region of the inner surface of the longitudinal opening in an edge layer adjacent to the respective inner surface of the longitudinal opening which is increased as a result of a chemical/thermal edge layer treatment compared to the hardness that the portal axle has in a core region present outside the edge layer.

21. The portal axle according to any one of claim 18, wherein at least the inner surface of the longitudinal opening is provided with an oxide layer.

22. A method for producing a portal axle according to claim 15, comprising the following work steps: a) provision of a portal axle blank comprising the axle centre part and kingpin moulded components; b) introduction of a longitudinal opening in at least one of the mould components; c) optional edge layer treatment of the portal axle in the region of an inner surface of the longitudinal opening and/or in the region of an outer surface of the portal axle; d) optional oxidation of an inner surface of the longitudinal opening and/or an outer surface of the portal axle.

23. The method according to claim 22, wherein the portal axle is subjected to edge layer treatment throughout after the longitudinal opening has been introduced.

24. The method according to either claim 22, wherein work step c) is carried out as chemical/thermal surface layer treatment.

25. The method according to claim 24, wherein the edge layer treatment increases the N and/or C content at least in the region of the inner surface of the longitudinal opening in an edge layer adjacent to the respective inner surface of the longitudinal opening.

26. The method according to claim 22, wherein the provision of the portal axle blank (work step a)) comprises forging and/or casting the blank from a steel material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The invention is explained in more detail below on the basis of a drawing representing an exemplary embodiment. The schematic drawings show the following:

[0057] FIG. 1 a portal axle for a wheel set of a low-floor rail vehicle;

[0058] FIG. 2 a section of the portal axle in a section along the longitudinal axis L-L of the portal axle shown in FIG. 1;

[0059] FIG. 3 a section of an alternative configuration of the portal axle in a sectional view corresponding to FIG. 2;

[0060] FIG. 4 a frontal view of the portal axle;

[0061] FIG. 5 a longitudinal section of the portal axle along the section line A-A shown in FIG. 4.

DESCRIPTION OF THE INVENTION

[0062] The portal axle 1 is forged in one piece from a suitable quenched and tempered steel composed in accordance with DIN EN ISO 683. In this case, the portal axle 1 has an axle centre part 2 which has the basic shape of a flat rectangle with a length L extending along a longitudinal axis L-L which is greater than the width B of the axle centre part 2.

[0063] The axle centre part 2 has an upper side 3, which is assigned in use to a chassis of a low-floor rail vehicle (not shown here). In each of the end sections 6, 7 of the axle centre part 2 adjoining the narrow sides 4, 5 of the axle centre part 2, there is a flange 8, 9 which is formed in one piece with the axle centre part 2. In the longitudinal side view (FIG. 5) the portal axle thus has the basic shape of a U, the legs of which are formed by the flanges 8, 9 and the base of which is formed by the axle centre part 2.

[0064] In a first embodiment, the longitudinal section of which is shown in FIGS. 2 and 5, a kingpin 10, 11 directed outwards away from the axle centre part 2 is forged in one piece on each of the flanges 8, 9. The longitudinal axes L10, L11 of the kingpins 10, 11 are aligned coaxially to each other and parallel to the central longitudinal axis L-L of the axle centre part 2.

[0065] The kingpins 10, 11, the flanges 8, 9 and the axle centre part 2 form moulded components from which the portal axle 1 is formed.

[0066] In the embodiments shown in FIGS. 1, 2, 4 and 5, a longitudinal opening 12, 13 is drilled in each of the kingpins 10, 11, which leads as a through-opening with a constant opening cross-section from the free end face 14, 15 of the kingpin 10, 11 to the side surface 16, 17 facing the axle centre part 2 of the flange 8, 9 bearing the respective kingpin.

[0067] In addition, two longitudinal openings 18, 19 are drilled into the axle centre part 2 starting from its narrow side 4 assigned for example to the flange 8, which extend as through-openings from the narrow side 4 to the opposite narrow side 5 of the axle centre part 2 and are aligned in parallel to each other and to the longitudinal axis L-L of the axle centre part 2 in such a way that they are positioned at the same distance from the next adjacent longitudinal side 20, 21 of the axle centre part 2. The diameter of the longitudinal openings 18, 19 is dimensioned in such a way that there is a minimum wall thickness WDmin between the upper side 3 and the opposite lower side 23 of the axle centre part 2 in each case, which corresponds to 0.1 to 0.25 times the distance AB between the upper side 3 and the lower side 23 (0.1ABWDmin0.25 AB). For example, the wall thickness WD is in practice equal to 0.125 times the distance AB between top side 3 and bottom side 23 (WD=0.125AB).

[0068] After the forging technique production of the portal axle 1 carried out in the usual manner, heat treatment carried out in the same known manner to set the mechanical properties, a stress-relieving annealing also carried out conventionally, the drilling of the longitudinal openings 12, 13, 18, 19 and the mechanical finishing of the entire outer contour of the portal axle except for the seats for bearings, seals and brake calliper hubs, which were finally coated with molybdenum, the portal axle 1 was subjected to edge layer treatment.

[0069] In this surface layer treatment, the portal axle 1 was nitrided over a period of 84 h and at a temperature of 520 C. in an atmosphere consisting of ammonia gas. The portal axle was then subjected to an oxidation process in a conventional manner.

[0070] After the edge layer treatment, the portal axle 1 exhibited an increased Vickers hardness of 790 HV compared to the base material of 340 HV in the region of its surfaces including the inner surfaces of the longitudinal openings 12, 13, 18, 19. The total thickness of the edge layer was approx. 0.7 mm.

[0071] The surfaces were then subjected to various corrosion tests and blasting tests with gravel to verify impact resistance. Compared to conventional portal axles, the surface-coated axle showed no signs of corrosion either in salt spray tests or during storage over a period of 3 months under extreme conditions in an acid-laden atmosphere. The shooting tests were carried out with track gravel and an impact speed of up to 360 km/h. The component surfaces were subsequently still intact.

[0072] The alternative embodiment of a portal axle shown in FIG. 3 is based on the portal axle 1 shown in FIGS. 1, 2, 4 and 5. In this case, the flanges 8 of the alternative embodiment of the portal axle each bear a separately prefabricated kingpin 10, which is shrunk in a known manner in itself into an opening 22 provided in the respective flange 8 or fixed in another suitable manner. As for the kingpin 10 shown in FIG. 2, the kingpin 10 also has a longitudinal opening 12, which leads from the free end face 14 to the side surface 16 of the flange 8, which is assigned to the axle centre part 2 of the portal axle.

[0073] In contrast to the longitudinal opening 12, 13 of the kingpin 10.11 with its constant opening diameter, the longitudinal opening 12 of the kingpin 10, however, has a first section 12a starting from the side surface 16 of the flange 8 assigned to the axle centre part 2, which transitions via a tapered step into a second section 12b, which leads to the free end face 14a of the kingpin 12. The first section 12a has a larger diameter than the second section 12b and extends in the region of the kingpin 10 in which the kingpin 10 has its largest volume.

[0074] For the sake of clarity, the alternative embodiment with the prefabricated kingpin 8 shrunk into the opening 22 of the flange 8 is shown here only for the first end section 6 of the portal axle concerned, the shape and structure of which otherwise correspond to those of portal axle 1. Of course, the other end section 7 of the portal axle 1 has a correspondingly designed arrangement of flange and kingpin. Here, too, the flanges 8 and the corresponding flange (not shown here) on the other side of the axle centre part 2 have been forged in one piece with the axle centre part 2.

REFERENCE NUMERALS

[0075] FIGS. 1, 2, 4, 5: [0076] 1 portal axle [0077] 2 axle centre part [0078] 3 upper side of axle centre part 2 [0079] 4, 5 narrow sides of the axle centre part 2 [0080] 6, 7 end sections of the axle centre part 2 [0081] 8, 9 flanges [0082] 10, 11 kingpins [0083] 12, 13 longitudinal openings of the kingpins 10, 11 [0084] 14, 15 free end faces of the kingpins 10, 11 [0085] 16, 17 side surfaces of the flanges 8, 9 [0086] 18, 19 longitudinal openings [0087] 20, 21 longitudinal sides of the axle centre part 2 [0088] 23 underside of the axle centre part 2 [0089] B width of the axle centre part 2 [0090] L length of axle centre part 2 [0091] L-L longitudinal axis of the axle centre part 2 [0092] L10, L11 longitudinal axes of the kingpins 10, 11 [0093] FIG. 3: [0094] 2 axle centre part [0095] 6 end section of the axle centre part 2 [0096] 8 flange of the alternatively designed portal axle [0097] 10 kingpin of the alternatively designed portal axle [0098] 12 longitudinal opening of the kingpins 10 [0099] 12a first section of the longitudinal opening 12 [0100] 12b second section of the longitudinal opening 12 [0101] 14 free end face of the kingpin 10 [0102] 16 side surface of the flange 8 [0103] 22 opening of the flange 8