FR3130667A1 - device and method for locating a particular area on a bent tube - Google Patents

Abstract

The present invention relates to a positioning device (10) for identifying at least one particular zone (8) on a bent tube (1). The positioning device (10) comprises a first arm (20) and a second arm (40), the first arm (20) being movable relative to the second arm (40) in rotation at least about a pivot axis ( AXP), said positioning device (10) comprising an elongated instrument (60) with at least one degree of freedom in translation along a positioning axis (AXL) orthogonal to the pivot axis (AXP) with respect to one of said first arm (20) and second arm (40), said elongated instrument (60) being configured to position said particular area (8) in use with respect to a reference point (PTREF) of said positioning device (10). Abstract Figure: Figure 3

Description

device and method for locating a particular area on a bent tube

The present invention relates to a device and a method for locating a particular zone on a curved tube.

A curved tube can usually have particular areas that need to be treated for functional or identification purposes. Such processing may consist of sticking a label on the tube, affixing a mark on the tube, mechanically and/or electrically linking the tube to another element, etc.

For example, a curved tube may have an area to accommodate a label and/or marking. The label and/or marking may include one or more identifiers, an arrow indicating a direction of fluid circulation in the tube or others.

According to another example, a bent tube may have an area that must have paint savings, possibly to be connected to a metallization or other circuit.

Such a particular zone is usually positioned using a predetermined dimension starting from the beginning of a curved sector. Positioning an area from a predetermined dimension starting from a reference point located on a curved part of the curved tube is tricky. Determining precisely the position of the reference point is indeed difficult. If the reference point corresponds to the beginning of a curved part, it is difficult to determine with precision and in a repeatable way the position of this reference point.

To correctly position the particular zone(s) on a bent tube, a first method proposes manufacturing a reference tube comprising the particular zone(s) to undergo treatment. The reference tube is then attached to the bent tube during manufacture. An operator then manually transfers the position of the particular zone or zones of the reference tube onto the bent tube during manufacture.

This first method is effective but requires repeating a delicate position copying operation for each bent tube to be manufactured. In addition, this first method requires having at least one reference tube per type of bent tube to be manufactured. By way of example, a vehicle and in particular an aircraft may comprise numerous curved tubes. Storing at least one reference tube for each bent tube of each type of vehicle can then cause difficulties. In particular, the storage space needed to store the reference tubes can be significant. It is also advisable to properly reference the reference tubes.

A second method consists of using a three-dimensional measurement system. Such a three-dimensional measuring system can precisely position a point on a bent tube with good repeatability. However, this second method requires the use of a relatively expensive three-dimensional measurement system and the training of operators. The cost of implementing the second method can then be high compared to the simple use of reference parts according to the first method.

The object of the present invention is therefore to propose an innovative device and method for reliably and repeatedly positioning at least one particular zone on a bent tube.

The present invention thus relates to a positioning device for identifying at least one particular zone on a bent tube.

The positioning device comprises a first arm and a second arm, the first arm being movable relative to the second arm in rotation at least about a pivot axis, said positioning device comprising an elongated instrument with at least one degree of freedom in translation along a positioning axis orthogonal to the pivot axis relative to one of said first arm and second arm, said elongated instrument being configured to position said particular zone in use relative to a reference point of said positioning device.

According to one example, the positioning device comprises a ball joint between the first arm and the second arm conferring freedom of movement in rotation around the pivot axis and around an axis of rotation to the first arm relative to the second arm. Such a ball and socket joint may comprise a rod passing through a ball, the rod being fixed to one arm and the ball being arranged in a cage fixed to the other arm.

According to another example, the positioning device comprises a pivot joint between the first arm and the second arm only conferring freedom of movement in rotation about the pivot axis on the first arm relative to the second arm. Such a pivot joint may comprise a rod passing through the first arm and the second arm along the pivot axis, and for example a screw.

A pivot connection between the first arm and the second arm makes it possible to precisely position the first arm and the second arm in a plane containing the curved section, and therefore makes it possible to position a particular zone precisely and in a reproducible manner.

Therefore, the positioning device can be used to determine where a particular area should be on a bent tube. To this end, the first arm and the second arm form a system with variable angulation able to be placed on the curved tube at the level of a curved section. Such a curved section takes the form of a section operating at least one change of direction. The first and the second arm can rest respectively on two substantially straight sections of the curved tube located on either side of the curved section.

This positioning device makes it possible to define a reference point at the level of the positioning device as such. The elongated instrument then makes it possible to position a particular zone, and for example the beginning of a particular zone, on the curved tube with respect to the reference point.

Therefore, the positioning device makes it possible to define a reference point that is easy to identify, this reference point being able to be located outside the bent tube and in particular outside a zone where the bending begins, which is difficult to identify.

In order to be adaptable to multiple zones of the same curved tube or to multiple different curved tubes, the elongated instrument can slide along one of the first arms and second arms.

Thus, the positioning device according to the present disclosure can make it possible to relatively accurately and repeatably position a particular zone at any position on a bent tube. The positioning device can furthermore have a reasonable cost and does not require a long training of operators.

The positioning device may include one or more of the following features.

According to one possibility, at least one carrier arm from among the first arm and the second arm carries at least one counter-form configured to conform to a shape of a section of said bent tube.

The positioning device may have no counter-form, but may be provided with at least one counter-form, in particular to increase its precision.

A counter-form makes it possible to correctly press and position the positioning device against the bent tube. The angular spacing between the first arm and the second, at least with respect to the pivot axis, can be modified until the counter-form(s) are correctly in contact with the curved tube.

Thus, at least the first arm, for example, can carry at least one so-called counter-form "first counter-form", the first counter-form(s) having a shape complementary to a shape of a first substantially straight section of a curved tube.

Optionally, the second arm can carry at least one counter-form called “second counter-form”, the second counter-form(s) having a shape complementary to a shape of a second substantially straight section of a curved tube. In this case, the first counter-form(s) and the second counter-form(s) make it possible to maintain the first arm and the second arm in a plane passing through the curved section and through the two sections which surround it.

The positioning device can have several sets of counter-forms, each set having at least one counter-form adapted to at least one section of a particular bent tube. For example, several different bent tubes can have tubular shapes of different diameters. Each set is then adapted to a particular diameter. In this case, each counter-form can be connected to an arm by a reversible means, for example a screwing means or a sliding connection. An operator can thus change the counter-forms according to the bent tube to be treated.

According to a possibility compatible with the previous ones, at least one counter-form can be stationary with respect to the associated support arm or can comprise at least one degree of freedom with respect to this support arm.

According to a possibility compatible with the previous ones, said counter-form can then be in sliding connection, namely only with one degree of freedom in translation, with the corresponding support arm.

Therefore, an operator can slide the counter-form along the associated arm to position it appropriately with respect to the curved tube.

According to a possibility compatible with the previous ones, a counter-form can comprise a half-shell having a notch through which a rail of the support arm passes or said support arm comprises a notch in which a rail of the counter-form slides.

According to a possibility compatible with the previous ones, a counter-form can comprise at least one proximal guide guiding a translation of the elongated instrument.

The counter-form and the elongated instrument can have complementary shapes so that the counter-form can guide the translation of the elongated instrument. The elongated instrument is thus correctly positioned in relation to the arms.

For example, the proximal guide may include a proximal rim attached against the elongated instrument or a proximal slide forming a passage in which the elongated instrument slides.

The elongated instrument can simply rest against an edge of the proximal guide along an axis parallel to the positioning axis, or can slide in a groove delimited by the counter-form.

According to a possibility compatible with the previous ones, at least one arm among said first arm and said second arm can comprise at least one distal guide to guide a translation of the elongated instrument.

At least one arm and the elongated instrument can have complementary shapes so that the arm-shape can guide the translation of the elongated instrument. The elongated instrument is thus correctly positioned in relation to the arms.

For example, each arm includes such a distal guide.

For example, said distal guide may comprise a distal rim attached against the elongated instrument or a distal slide forming a path in which the elongated instrument slides.

The elongated instrument can simply rest against an edge of the distal guide along an axis parallel to the positioning axis, or can slide in a groove delimited by the arm concerned.

According to a possibility compatible with the previous ones, the elongated instrument is guided in translation by the aforementioned proximal guide and the distal guide.

The elongated instrument then extends along a transverse axis perpendicular to the positioning axis between the proximal guide and the distal guide, the proximal guide being located between the curved tube and the distal guide.

According to a possibility compatible with the previous ones, the elongated instrument can comprise a ribbon with a rectangular section orthogonal to the positioning axis.

For example, the ribbon is graduated. The elongated instrument can then be a ruler or can take the form of a rod having a predetermined length between a mark and one of its ends.

According to a possibility compatible with the previous ones, the elongated instrument can comprise at least one mark configured to be positioned at right angles to a reference axis passing through the reference point, the reference axis being located in use on said curved tube at the interface seen along the pivot axis between a first face of the first arm facing the bent tube and a second face of the second arm facing the bent tube.

Thus, the positioning device makes it possible to define a reference point located in the extension of sections of the bent tube located on either side of the bent section. By construction, this reference point is on an axis located at the interface between the first face and the second face.

Therefore, the elongated instrument can, for example, make it possible to position one end of this elongated instrument at a particular distance from the reference point. An operator can then position a mark on the bent tube to the right of this end.

Such a positioning device according to the present disclosure can make it possible to apply the following method.

Indeed, the present disclosure also relates to a method for identifying at least one particular zone on a bent tube, the bent tube comprising a first section followed by a bent section, the bent section being extended by a second section. The first section and the second section can be substantially straight, unlike the curved section which in fact has a radius of curvature

This process comprises the following steps:

- determination of a reference point outside the bent tube, the reference point possibly facing a convex zone of the bent section, the reference point being positioned at the intersection between a first straight line extending the first section and a second straight line extending the second section,

- positioning of the particular zone at a predetermined distance from said reference point on one of said first section and second section.

The reference point can be present in a reference plane containing the first line and the second line.

According to one possibility, the first section may have the shape of a first cylinder centered on a first axis and the second section may have the shape of a second cylinder centered on a second axis, said reference plane possibly containing the first axis and the second axis.

The invention and its advantages will appear in more detail in the context of the following description with examples given by way of illustration with reference to the appended figures which represent:

there , a view illustrating the method of the invention,

there , a view illustrating the method of the invention,

there , a diagram illustrating a positioning device according to the invention,

there , a diagram illustrating an example of counter-frome of a positioning device according to the invention,

there , a diagram illustrating an example of counter-frome of a positioning device according to the invention,

there , a diagram illustrating an example of a counter-form of a positioning device according to the invention, and

there , a diagram illustrating the operation of the positioning device according to the invention.

The elements present in several distinct figures are assigned a single reference.

There has a curved tube 1. Such a curved tube 1 comprises at least a first section 2, possibly rectilinear. For example the first section 2 comprises a first cylinder 3, for example with a circular base, extending along a first axis AX1. The first axis AX1 can be an axis of symmetry of the first section 2.

The first section 2 is extended by a curved section 5. The curved section 5 can be curved in the usual way, for example to present one or more changes of direction and possibly a radius of curvature with respect to a center of curvature CTR.

The curved section 5 is then extended by a second section 6, possibly rectilinear. For example the second section 6 comprises a second cylinder 7, for example with a circular base, extending along a second axis AX2. The second axis AX2 can be an axis of symmetry of the second section 6.

The present disclosure relates in particular to a method for identifying at least one particular zone 8 on the bent tube 1, for example to determine the position of one end of the particular zone 8.

This method comprises a step STP1 for determining a reference point PTREF, the particular zone 8 having to be positioned with respect to this reference point PTREF. In an innovative and surprising way, this reference point PTREF does not belong to the bent tube 1. In particular, the reference point PTREF is located outside the bent section 5, if necessary opposite the center of curvature CTR by relative to the curved section 5. Thus, the curved section 5 is located in a space comprised between the reference point PTREF and the center of curvature CTR.

For this purpose, the reference point PTREF is positioned at the intersection between a first straight line D1 extending the first section 2 and a second straight line D2 extending the second section 6.

According to the example illustrated, the first straight line D1 can pass through a generatrix of the first section 2, present in a reference plane PREF containing the first axis AX1 and the second axis AX2. More precisely, the first section 2 comprises, at the intersection between the first section 2 and the reference plane PREF, a first internal segment with regard to the center of curvature CTR and a first external segment. Therefore, the first line D1 passes through the first outer segment.

Similarly, the second line D2 can pass through a generatrix of the second section 6, present in the reference plane PREF. More precisely, the second section 6 comprises, at the intersection between the second section 6 and the reference plane PREF, a second internal segment with regard to the center of curvature CTR and a second external segment. Therefore, the second line D2 passes through the second external segment.

With reference to the , the method further comprises a step of positioning STP2 of the particular zone 8 at a predetermined distance DIST from the reference point PTREF on one of the first section 2 and second section 6.

As a result, this method can prove to be relatively easily reproducible, and does not depend on the delicate location of the start of the curved section 5. Indeed, the reference point PTREF is only positioned according to the first section 2 and the second section 6 .

Figures 3 to 6 illustrate a positioning device 10 able to implement this method.

The positioning device 10 comprises a first arm 20 and a second arm 40. The first arm 20 is for example in ball or pivot connection with the second arm 40. The first arm 20 is thus movable relative to the second arm 40 in rotation at the less around a pivot axis AXP, or even only mobile in rotation around said pivot axis AXP and an axis of rotation, or even only mobile in rotation around said pivot axis AXP.

The first arm 20 is thus connected to the second arm 40 by an articulation. For example, the first arm 20 is attached to the second arm 40 via a screw which extends along the pivot axis AXP as part of a pivot connection.

Thus, the first arm 20 and the second arm 40 form an object that can have a variable angle between this first arm 20 and this second arm 40.

Close to the pivot axis AXP, the first arm 20 and the second arm 40 make it possible to define a reference axis AXREF passing through the aforementioned reference point PTREF in use. Indeed, this reference axis AXREF extends at the intersection of a first face 25 of the first arm 20 and a second face 45 of the second arm 40 seen along the pivot axis AXP. The reference axis AXREF can be parallel to the swivel axis AXP.

In addition, the positioning device 10 comprises an elongated instrument 60 movable at least in translation along a positioning axis AXL orthogonal to the pivoting axis AXP. At least the first arm 20, or even each arm 20, 40, has the capacity to carry the elongated instrument 60.

Therefore, in use on a curved tube 1, the first arm 20 and the second arm 40 make it possible to materialize the reference point PTREF, the elongated instrument 60 making it possible to establish the required distance from this reference point PTREF.

For this purpose, the elongated instrument 60 may include at least one mark 63 configured to be positioned at the right of the reference axis AXREF. For example, the elongated instrument 60 has graduations forming such marks. For example, the elongated instrument 60 is graduated in a unit of measurement of distance, centimeters or other, the graduations starting from zero at the level of one end of this elongated instrument 60. It is then sufficient for an operator to place the graduation corresponding to the desired distance at the level of the reference axis AXREF as explained below.

For example, the elongated instrument 60 can take the form of a ribbon 61 with a rectangular section in a plane orthogonal to the positioning axis AXL. For example, the elongated instrument 60 has a ruler.

To facilitate the positioning of the positioning device 10, this positioning device 10 can comprise one or more counter-forms 80. The reference 80 is associated with any counter-form for convenience, the references 81, 82 being used to designate if necessary special counter-forms. The expression "each counter-form" is used independently of the number of counter-forms, namely in the presence of one or more counter-forms and independently of the possibility of having different counter-forms within a same positioning device 10.

Each counter-form 80 is in particular carried by one of the first arm 20 and second arm 40 and has a shape complementary to a shape of a section 2.6 of the curved tube 1 for which the counter-form 80 is suitable. Therefore, the bottom 810, 820 of the shape of a counter-shape complementary to a shape of a section 2.6 of the curved tube 1 is aligned with the first face 25 or the second face 45 of the corresponding support arm.

Thus, the first arm 20 carries at least a first counter-form 81, or even the second arm 40 carries at least a second counter-form 82. Therefore, a first bottom 810 of the shape of the first counter-form 81 can be in alignment with the first face 25, a straight line 811 passing through this first face 25 also passing against this first bottom 810. If necessary, a second bottom 820 in the shape of the second counter-form 82 can be in the alignment of the second face 45, a line 821 passing through this second face 45 also passing against this second bottom 820.

Furthermore, each counter-form 80 can be immobile or in sliding connection with the first arm 20 or the second arm 40 which carries it, this arm 20, 40 being called carrying arm for convenience. Optionally, a carrier arm may comprise a stop near the pivot axis AXP to limit the translational movement of a counter-form 80. According to the example illustrated, the first arm 20 thus comprises a first stop comprising in addition the first face 25, and the second arm 40 comprises a second abutment additionally comprising the second face 45.

The sliding connection maintaining a mobile counter-form relative to an arm is a plus which makes it possible to widen the field of action of the same positioning device 10. Indeed this sliding connection makes it possible to make a positioning device 10 compatible with a plurality of different bent tubes. Such a slide connection also facilitates the maintenance and replacement of different counter-forms on the same arm of the positioning device 10 in order to adapt it to different tube diameters.

Alternatively, at least one or even each counter-form can be fixed to an arm so as to be immobile with respect to this arm. For example, the counter-form and the arm can form one and the same piece or can be fixed to one another by the usual means of screwing, gluing or other means.

According to another aspect, the positioning device 10 can comprise assistance members to guide and/or maintain the elongated instrument 60.

According to an example not shown, an assistance member may comprise a clamping system, such as a clamp, a screw or the like to immobilize the elongated instrument 60 with respect to a carrying arm.

To guide a translation of the elongated instrument 60, an assistance member may comprise a proximal guide 90 of a counter-form 80. Optionally, each counter-form 80 may have such a proximal guide 90.

In a complementary or alternative manner, an assistance member may comprise at least one distal guide 30 of an arm 20, 40. Optionally, each arm 20, 40 comprises such a distal guide 30.

According to the example illustrated, the elongated instrument 60 is guided in translation by a first proximal guide 90 of a first counter-form 81 and a first distal guide 30 of the first arm 20 while being arranged along a transverse axis AXT between the first distal guide 30 and the first proximal guide 90. The transverse axis AXT is orthogonal to a plane passing through the positioning axis AXL and the pivoting axis AXP,

Figures 4 to 6 illustrate non-exhaustive examples of embodiment of a support arm carrying a counter-form 80 and an elongated instrument 60. Figures 4 to 6 illustrate a first arm 20 and a first counter-form 81 but the second arm 40 and a possible second counter-form 82 could have identical characteristics.

Thus, the counter-form 80 may comprise a half-shell 85. The half-shell 85 may have a sector shaped like a first section 2 of a curved tube 1. FIGS. 4 to 6 illustrate, for example, counter-forms 80 having a half-cylinder shaped face corresponding to a first cylindrical section 2.

According to another aspect, a counter-form 80 can be in a sliding type connection with a body 21 of the support arm, the first arm 20 in this case.

According to the example of a slide-type connection illustrated in FIGS. 4 and 5, the half-shell 85 may comprise a notch 86 traversed by a rail 23 projecting from the body 21. According to the example of a slide-type connection illustrated on the , the body 21 of the carrier arm has a notch 26 in which slides a rail 87 of the counter-form 80.

Independently of the presence or not of a slide connection between a counter-form 80 and a support arm, figures 4 to 6 illustrate examples of assistance device.

According to the guide example illustrated in FIGS. 4 and 6, the body 21 may have a protuberance forming a distal guide 30 comprising a distal rim 31 attached against the elongated instrument 60. Similarly, the counter-form 80 may have a protuberance forming a proximal guide 90 comprising a proximal rim 91 attached against the elongated instrument 60. The elongated instrument 60 is then in contact along the transverse axis AXT with the distal rim 31 and the proximal rim 91, or even may be in support on the body 21 in a plane parallel to the positioning axis AXL and to the transverse axis AXT.

According to the guidance example shown in the , the body 21 may have an L-shaped protrusion forming a distal guide 30 comprising a distal slide 32 delimiting a path 33. Similarly, the counter-form 80 may have an L-shaped protuberance forming a proximal guide 90 comprising a proximal slide 92 delimiting a passage 93. Each slide 32, 92 defines a rim and an upper part. The elongated instrument 60 is then in contact along the transverse axis AXT with an edge of the distal slide 32 and an edge of the proximal slide 92, or even can be arranged between the body 21 and the upper parts of the slides 32, 92 according to an axis orthogonal to the transverse axis AXT.

Regardless of how the positioning device is made, the illustrates the operation of this positioning device 10.

The first arm 20 and the second arm 40 are spaced apart in rotation relative to each other so as to rest on the first section 2 and the second section 6. The first counter-form(s) 81 and the second possible counter-forms 82 are joined respectively to the first section 2 and to the second section 6. For this purpose, at least a first counter-form 81 can optionally be moved in translation relative to the first arm 20 and/or at least a second counter-form -shape 82 can optionally be moved in translation relative to the second arm 40.

This step is used to position the reference point PTREF.

From then on, the operator can move the elongated instrument 60 in translation with respect to the first bars 20 or to the second arm 40 depending on the intended location of the particular zone 8. According to the example illustrated, the elongated instrument 60 is a ruler. The operator therefore places the graduation of the ruler corresponding to the desired distance to the right of the reference axis AXREF. The operator can then place a first mark on the curved tube 1 to the right of an initial graduation of the ruler, and to the right of one end of the ruler according to the example illustrated.

Thus, the positioning device 10 makes it possible to easily position the start of the desired particular zone 8 on the bent tube. The operator can position the end of the particular zone by affixing a second mark on the curved tube 1 at a predetermined length from the first mark. The operator can then appropriately treat the particular zone 8, for example by sticking a label there, by reserving the zone to protect it from paint, etc.

Of course, the present invention is subject to many variations in its implementation. Although several embodiments have been described, it is clearly understood that it is not conceivable to identify exhaustively all the possible modes. It is of course possible to replace a means described by an equivalent means without departing from the scope of the present invention.

Claims (14)

Positioning device (10) for identifying at least one particular zone (8) on a bent tube (1),
characterized in that the positioning device (10) comprises a first arm (20) and a second arm (40), the first arm (20) being movable relative to the second arm (40) in rotation at least around a pivot axis (AXP), said positioning device (10) comprising an elongated instrument (60) with at least one degree of freedom in translation along a positioning axis (AXL) orthogonal to the pivot axis (AXP) relative to one of said first arm (20) and second arm (40), said elongated instrument (60) being configured to position said particular zone (8) in use with respect to a reference point (PTREF) of said positioning device (10) . Positioning device according to claim 1,
characterized in that at least one carrier arm among the first arm (20) and the second arm (40) carries at least one counter-form (80) configured to be shaped to a shape of a section (2, 6) of said bent tube (1). Positioning device according to claim 2,
characterized in that said counter-form (80) is in sliding connection with said carrier arm. Positioning device according to any one of Claims 2 to 3,
characterized in that said counter-form (80) comprises a half-shell (85) having a notch (86) traversed by a rail (23) of said support arm or said support arm comprises a notch (26) in which a rail slides (87) of the counter-form (80). Positioning device according to any one of Claims 2 to 4,
characterized in that said counter-form (80) comprises at least one proximal guide (90) guiding a translation of the elongated instrument (60). Positioning device according to claim 5,
characterized in that said proximal guide (90) comprises a proximal flange (91) attached against the elongated instrument (60) or a proximal slide (92) forming a passage (93) in which the elongated instrument (60) slides. Positioning device according to any one of Claims 1 to 6,
characterized in that at least one of said first arm (20) and said second arm (40) includes at least one distal guide (30) for guiding translation of the elongated instrument (60). Positioning device according to claim 7,
characterized in that said distal guide (30) comprises a distal flange (31) attached against the elongated instrument (60) or a distal slide (32) forming a path (33) in which the elongated instrument (60) slides. Positioning device according to any one of Claims 5 to 6 and any one of Claims 7 to 8,
characterized in that the elongated instrument (60) is guided in translation by the proximal guide (90) and the distal guide (30). Positioning device according to any one of Claims 1 to 9,
characterized in that said elongated instrument (60) is a ribbon (61) with a rectangular section (62) orthogonal to the positioning axis (AXL). Positioning device according to any one of Claims 1 to 10,
characterized in that said elongated instrument (60) comprises at least one mark (63) configured to be positioned at right angles to a reference axis (AXREF) passing through the reference point (PTREF), the reference axis (AXREF ) being located in use on said bent tube (1) at the interface seen along the pivot axis (AXP) between a first face (25) of the first arm (20) facing the bent tube (1 ) and a second face (45) of the second arm (40) facing the bent tube (1). Method for identifying at least one particular zone (8) on a bent tube (1), said bent tube (1) comprising a first section (2) followed by a bent section (5), the bent section (5) being extended by a second section (6),
characterized in that the method comprises the following steps:
- determination (STP1) of a reference point (PTREF) outside the bent tube (1), the reference point (PTREF) being positioned at the intersection between a first straight line (D1) extending the first section (2) and a second straight line (D2) extending the second section (6),
- positioning (STP2) of the particular zone (8) at a predetermined distance (DIST) from said reference point (PTREF) on one of said first section (2) and second section (6). Method according to claim 12,
characterized in that said reference point (PTREF) is present in a reference plane (PREF) containing the first straight line (D1) and the second straight line (D2). Method according to claim 13,
characterized in that said first section (2) having the shape of a first cylinder (3) centered on a first axis (AX1) and the second section (6) having the shape of a second cylinder (7) centered on a second axis (AX2), said reference plane (PREF) contains the first axis (AX1) and the second axis (AX2).