Device for assembling axisymmetric components

This application claims priority to European Application Serial Number 000870119.5 filed on May 31, 2000.

Flanges which are produced directly by turning in the thickness inside or outside at least one of the components are usually used for assembling axisymmetric components by bolting.

The term “bolting” means firmly securing by screwing tight using bolts or screws, pins or threaded rods which may be combined with nuts.

The type of flange most commonly used for assembling axisymmetric components, for example the bolted cones used as bearing pedestals, is an outer flange with or without reinforcements.

The flange factor is defined as a factor which takes into account the fact that the axis of the force passing through the body of the support and the axis of the screw are misaligned, which results in the creation of a bending moment. The value of the flange factor theoretically ranges between 1 (alignment of the forces) and infinity (complete misalignment).

The flange factor is proportionately larger the greater the misalignment. The reason for this is that this misalignment generates a lever arm (bending moment) which introduces an increase in the force passing through the screws during a detachment of the flanges. A large flange factor (>>1) is thus harmful to the mechanical behavior of a bolted assembly.

The aim of the presence of reinforcements on the flange is to reduce the flange factor. The reason for this is that these reinforcements make it possible to reduce the above-mentioned lever arm.

Inner flanges are also known as making it possible to reduce the flange factor, but generally they nevertheless do not have any reinforcements since they are very problematic to produce.

The present invention aims to propose a device for assembling two axisymmetric components by bolting, which does not have the drawbacks of the prior art.

In particular, the present invention aims to propose a solution which has a flange factor of close to 1.

The present invention is also directed towards proposing a process for producing an inner flange arranged on an axisymmetric structural component, this process being easy to carry out.

The present invention relates to an axisymmetric structural component, one of the ends of which is fitted with an inner circular flange for assembling, by bolting, the said axisymmetric structural component with a second axisymmetric structural component. The flange comprises housings for receiving fixing elements such as bolts, pins or threaded rods. The housings are arranged on the circumference of the flange at regular intervals. The housings are T-shaped in a longitudinal section and consist of a first essentially cylindrical portion which is longitudinally open on the inner face of the axisymmetric structural component and transversely open on the contact face of the flange in the assembly. A second essentially semi-cylindrical portion is mounted on the flange, which is also longitudinally open on the inner face of the said structural component, having an essentially D-shaped transverse section. The diameter of the first cylindrical portion is less than the diameter of the semi-cylindrical portion for each of the housings.

Advantageously, the axisymmetric structural component is made of aluminum.

The invention also relates to a process for manufacturing an inner circular flange arranged on an axisymmetric structural component, which is preferably conical or cylindrical, and which has housings for receiving fixing elements such as bolts, pins or threaded rods. The housings are machined at regular intervals on the circumference of the flange preferably using a milling cutter which is essentially T-shaped and such that the axis of the said milling cutter moves, during machining, in a direction which is essentially perpendicular to the rotational axis of the component, preferably radially, while at the same time remaining parallel to this rotational axis.

FIGS. 1 a and 1 b each represent a perspective view of an axisymmetric component fitted with an outer flange with reinforcements, according to the prior art.

FIG. 2 represents a perspective view of an axisymmetric component fitted with an inner flange with reinforcements, according to the prior art.

FIG. 3 represents a perspective view of an axisymmetric component fitted with an inner flange with reinforcements, according to the invention.

FIG. 4 represents a view in section along AA of an assembly of two axisymmetric components, one of which is fitted with a flange according to the invention, as represented in FIG. 3 .

FIGS. 1 a and 1 b represent one particular embodiment of an axisymmetric structural component according to the prior art (for example a cone) to be assembled.

In order to reduce the flange factor, it is also possible to machine an inner flange, as represented in FIG. 2 . In this case, it is theoretically possible to have reinforcements 4 between the recesses 3 ; however, in practice, this operation is difficult to perform.

The present invention solves this problem by producing a flange inside the first axisymmetric structural component to be assembled as represented in FIGS. 3 and 4.

In a first stage, a solid flange 2 is produced by turning inside the first axisymmetric structural component 1 to be assembled, which corresponds in this case to a conical component. This flange is then machined in particular using a T-shaped milling cutter in order to make the orifices corresponding to the housings 60 , 61 , 62 into which may be introduced the head of a bolt 70 , 71 , 72 to assemble the conical component 1 with the second axisymmetric structural component 10 as shown more particularly in FIG. 4 .

FIG. 4 represents a view in section A—A along a plane passing through the rotational axis of the component 1 , represented in FIG. 3 . Such a section will be referred to herein as a “longitudinal section”. Similarly, the term “cross section” will be denoted herein as being the intersection of the component 1 with a plane which is perpendicular to its rotational axis.

Each of the housings 60 , 61 , 62 will thus be T-shaped in longitudinal section. Each housing will consist of a first essentially cylindrical portion 6 which is longitudinally open on the inner face (x) of the axisymmetric structural component 1 and transversely open on the contact face (y) of the flange 2 in the assembly, on which is mounted an essentially semi-cylindrical second portion 6 ′ which is also longitudinally open on the inner face (x) of the said structural component 1 .

This technique for producing an inner flange has several advantages. The fastening structure is such that the flange factor is very close to 1. The technique is industrially viable, in particular for small tapering of the components to be assembled; the use of material is optimized, which may be preferred with the use of aluminum, which has a low specific strength. For a given overall size, the amount of material available is limited.