EP0564423A1

EP0564423A1 - A railway bogie frame

Info

Publication number: EP0564423A1
Application number: EP93830137A
Authority: EP
Inventors: Paolo Astolfi; Franco Luciano; Fabrizio Brughera; Stefano Govone
Original assignee: Fiat Ferroviaria SpA
Current assignee: Fiat Ferroviaria SpA
Priority date: 1992-04-03
Filing date: 1993-04-02
Publication date: 1993-10-06
Also published as: ES1031403U; IT1259517B; ITTO920310A0; PT9156T; ITTO920310A1; ES1031403Y

Abstract

A railway bogie frame, comprising a substantially quadrangular metal structure (1) formed by two longitudinal elements (2, 3) connected to each other by two transverse elements (4, 5) and to which support and fixing members (10-16) for the bogie equipments are secured. The longitudinal elements (2, 3) and the transverse elements (4, 5) are constituted by closed-cross -section hollow beams without weld-material solderings. The weldings on the hollow beams (2, 3; 4, 5) of the support and fixing members (10-16) for the bogie equipments are distributed so as the frame (1) can be dimensioned according to the fatigue limit of the beams without weld-materials solderings themselves.

Description

The present invention refers to bogie frames for railway vehicles, of the type comprising a substantially quadrangular metal structure formed by two longitudinal elements connected to each other by two transverse elements and to which support and fixing members for the bogie equipments are secured.
In the traditional railway bogie frames of the above-referenced type the longitudinal elements and the transverse elements are conventionally formed by hollow girders made by plates welded to one another.
This disposition, besides involving difficulties and high manufacturing costs as well as huge dimensions and weight, exhibits problems related to the fatigue failure limits of the weldings between the plates of the frame elements, which does constitute a critical aspect in connection with the operating life of the bogie.
The object of the present invention is to overcone the above mentioned drawbacks, and to provide a railway bogie frame adapted to be manufactured in a more simple and economical way, with reduced dimensions and weight and moreover enabling an appreciable increase of the fatigue failure limits of the structure.
According to the invention, this object is achieved essentially by virtue of the fact that the said longitudinal elements and the said transverse elements are constituted by closed-cross-section hollow beams without weld-material solderings.
By the term "weld-material solderings" it is to be intended, in the following description and claims, a tubular structure completely deprived of longitudinal joining lines, obtained for example by rolling, or with one longitudinal joining line made by forge or blacksmith welding, i.e. heating the edges to be joined at a temperature lower than the melting point but such that the material acquires a sufficient plasticity so as to allow joining of such edges under mechanical pressure.
According to a preferred embodiment of the invention, the two longitudinal elements have a quadrangular, normally square cross-section, and the two transverse elements have a curvilinear, normally circular cross-section. However, closed cross-sections of different shapes also come within the scope of the invention.
Preferably the longitudinal elements are formed in proximity to their ends with respective pairs of aligned openings through which the ends of the corresponding transverse elements are fitted, which ends are welded to the longitudinal elements in the area of the said openings.
In order to make the dimensions of the cross-sections of the longitudinal and of the transverse beams substantially exclusively determined by the fatigue limit peculiar of the said beams in connection with the maximum foreseen strains induced to the frame by the operation loads, the said support and fixing members for the bogie equipments are secured to the said longitudinal and transverse elements by means of weldings distributed so as the reductions of the fatigue limits that such weldings induce on the beams are localized where corresponding reductions of the strains generated on the frame by the operating loads occurr.
The main advantages of the bogie frame according to the invention with respect to the conventional frames can be summarized essentially in the following:

achievement of a fatigue limit even double than the limit obtained by adopting hollow girders made by plates welded to one another,
corresponding reduction of dimensions and weight,
reduction of deformations and pre-strains of the frame during manufacturing,
more simple and less costly manufacture and assembling.

The invention will now be disclosed in detail with reference to the accompanying drawings, provided purely by way of non limiting example, wherein:

figure 1 is a diagrammatic perspective view of a railway bogie frame according to the invention,
figure 2 is a plan view from above of figure 1,
figure 3 is a side elevational view according to arrow III of figure 2,
figure 4 is a longitudinally sectioned view along line IV-IV of figure 2,
figure 5 is a cross-sectional view along line V-V of figure 2, and
figure 6 is a front elevational view according to arrow VI of figure 2.

Referring to the drawings, reference numeral 1 generally designates as a whole a frame for railway vehicle bogies according to the invention, whose primary structure is constituted by two metal longitudinal elements 2, 3 parallel to each other and connected by two metal transverse elements 4, 5 parallel to each other.
As it can be seen in better detail in figure 5, the two longitudinal elements 2, 3 are constituted each by a hollow closed-cross-section beam without weld-material solderings. As previously explained, each beam 2, 3 can actually be formed without any weldings, and for instance manufactured by rolling, or it can be provided with one longitudinal joining line made during manufacturing by means of forge or blacksmith welding. In this case the joint edges, heated at such a temperature to acquire a sufficient plasticity, are let's say kneaded by swaging or mechanical pressure so as, following joining, the section has anyhow a constant thickness.
In the case of the shown example the two beams 2, 3 have a quadrangular cross-section, and in particular a square cross-section.
The two transverse elements 4, 5 are also constituted by hollow closed-cross-section metal beams without weld-material solderings, and are manufactured according to one or the other method disclosed with reference to the two longitudinal elements 2, 3. As it is better shown in figure 4, they are conveniently but not necessarily formed with a curvilinear cross-section, which in the example illustrated is circular, and cross at their respective ends corresponding pairs of openings 6 (figure 7) of same shape, formed in the respective longitudinal elements 2, 3.
The rigid connection is accomplished by means of annular solderings 7 between the transverse elements 4, 5 and the longitudinal elements 2, 3 in correspondence of the edges of the openings 6. These solderings must be executed taking any expedient suitable to minimize the internal strains.
On the ends of the longitudinal elements 2, 3 four overhanging respectively front 8 and rear 9 headstocks are fixed, also by welding, for the vertical and horizontal connections of the frame 1 to the axles of the railway bogie.
Supports and fixing elements for the connection of the various bogie equipments are fixed by welding along the sides of the quadrangular frame 1: in particular, they comprise the supports for the secondary suspension 10 disposed above the central zones of the two longitudinal elements 2, 3, the supports for anti-hunting devices, fixing brackets 12, 13, 14 and 15 fixed onto the transverse elements 4, 5, and supports 16 for the connection of the bogie axle boxes, applied in correspondence of the ends of the two longitudinal elements 2, 3. The distribution and shape of the solderings of the said support and fixing elements, and more particularly of those referenced as 10 and 12 - 15 is properly defined, according to what is shown in the drawings, so as the reductions of the fatigue limits that such solderings induce to the beams of the frame 1 are localized where corresponding reductions of the strains generated into the frame by the operating loads occurr. In this way the dimensions of the cross-sections of the beams 2, 3 and 4, 5 are substantially determined by the fatigue limit peculiar of the beans themselves without weld-material solderings, referred to the maximum strains. This enables an appreciable increase of the fatigue limit of the frame 1 as a whole, even with dimensions and weights lower than those of the conventional frames.
Naturally the details of construction of the frame may be widely varied with respect to what has been described and illustrated, without thereby departing from the scope of the present invention such as defined in the appended claims.

Claims

A railway bogie frame, comprising a substantially quadrangular metal structure formed by two longitudinal elements (2, 3) connected to each other by two transverse elements (4, 5) and to which support and fixing members (10-16) for the bogie equipments are secured, characterized in that the said longitudinal elements (2, 3) and the said transverse elements (4, 5) are constituted by closed-cross-section hollow beams without weld-material solderings.
A bogie frame according to claim 1, characterized in that the two longitudinal elements (2, 3) have a quadrangular cross-section.
A bogie frame according to claim 2, characterized in that the cross-section is square.
A bogie frame according to claim 1, characterized in that the said transverse elements (4, 5) have a curvilinear cross-section.
A bogie frame according to claim 4, characterized in that the cross-section is circular.
A bogie frame according to claim 1, characterized in that the said hollow beams (2, 3; 4, 5) are without any soldering.
A bogie frame according to claim 1, characterized in that the said hollow beams (2, 3; 4, 5) have a longitudinal joining line made by forge welding.
A bogie frame according to any of the preceeding claims, characterized in that the longitudinal elements (2, 3) are formed in proximity to their ends with respective pairs of aligned openings (6) through which the ends of the corresponding transverse elements (4, 5) are fitted, which ends are welded to the longitudinal elements (2, 3) in the area (7) of the said openings (6).
A bogie frame according to claim 1, characterized in that the said support and fixing members (10-16) are secured to the said longitudinal and transverse elements (2, 3; 4, 5) by solderings distributed so as the reductions of the fatigue limits that such solderings induce onto the beams (2, 3; 4, 5) are localized where corresponding reductions of the strains generated in the frame (1) by the operating loads occurr.