METHOD FOR PRODUCING AN ALUMINUM CRADLE WITH STRESS DISTRIBUTED ON THE REAR FENDERS, FOR A VEHICLE

Description

[0001] The invention relates to aluminium cradles, manufactured by extrusion (or spinning), machining and welding (or forging), and intended to equip certain vehicles, possibly of the automobile type, and more specifically the manufacture of such cradles.

[0002] Some vehicles, generally automobiles, include, usually in their front section, an aluminum subframe, an example of which is illustrated on the figure 1 .

[0003] On this figure 1 As in the other figures, the X direction is the longitudinal direction of the vehicle, which is substantially parallel to the side sides containing the side doors, the Y direction is the transverse direction of the vehicle, which is perpendicular to the X direction, and the Z direction is the vertical direction of the vehicle, which is perpendicular to the longitudinal X and transverse Y directions.

[0004] As illustrated, and as described in patent documents FR 3046590 and FR 3037305, a BA cradle comprises an extruded, machined TB cross member intended to be installed in a vehicle along the transverse direction Y, and having two ends opposite each other and to each of which are fixedly attached a front anchor piece (or "horn") PAV and a rear extension (or clevis) PB.

[0005] The cross member TB comprises two transverse ends ET (opposite to each other) and a transverse partition CT extruded along the transverse direction Y.

[0006] The front mounting of the subframe (BA) to the vehicle body is achieved via two front mounting brackets (PAV), right and left. Each front mounting bracket (PAV) is extruded along the transverse Y direction and comprises a lower section (PI) and an upper section (PS) that extend from each other. Each lower section (PI) is fixed to one end of the crossmember (TB) via weld beads and includes two vertical walls (PV) with holes defining a first mounting point (PA1, generally called E1) along the longitudinal X direction, for example, for mounting a front section of a wheel (or suspension) wishbone with a bolt. Each upper section (PS) includes holes defining a second vertical mounting point (PA2, generally called X2) for a bolt attached to a section of the body.

[0007] The rear anchoring of the BA cradle to the vehicle body is achieved via the two rear extensions PB, right and left. Each rear extension PB is extruded along the longitudinal direction X and machined to include a longitudinal partition CL extended by upper wings AS and lower wings AI, substantially horizontal and equipped with holes that define a third anchoring point PA3 (generally called E2), along the vertical direction Z, for example for the anchoring of a rear part of a wheel triangle.

[0008] Once the TB cross member, the PB rear extensions, and the PAV front anchor pieces have been extruded in their respective directions, the two transverse ends ET of the TB cross member can be pre-machined. For example, each transverse end ET can be pre-machined using a milling saw (e.g., with a 250 mm or 300 mm diameter disc) whose milling axis is perpendicular to the XZ plane.

[0009] Then, a manufacturing process is implemented comprising a first machining stage and a second welding stage.

[0010] In this first step, the two transverse ends ET of the TB cross member and the two front ends EV of the two rear extensions PB are machined. More precisely, and as illustrated in the figures 2 à 4 Each front end EV is machined using a tool with a machining axis positioned parallel to the vertical Z direction. This machining is initially performed along a first path parallel to the transverse Y direction (arrow F1 of the figure 2 ), to define a first interface zone ZI1 in a central part and an upper part. Then, this machining is carried out along a second path initially parallel to the transverse direction Y (arrow F2 of the figure 3 ), then curved relative to the latter (arrow F3 of the figure 3 ), to define a second interface zone ZI2, extending rearward from the first interface zone ZI1, into a lower part of the longitudinal partition CL and into the lower wing AI.

[0011] Also as illustrated on the figures 5 et 6 , each transverse end ET is machined using a tool having a machining axis placed parallel to the vertical Z direction with a path contained in the XY plane and then having a machining axis placed parallel to the transverse Y direction with a path contained in the XZ plane (see figure 6 ), to define in an upper part of its rear part a third interface zone ZI3 adapted for docking on the first interface zone ZI1.

[0012] In the second step, machined rear PR sections from the transverse ends AND cross member TB are welded respectively to the front EV ends of the two rear PB extensions. Alternatively, machined front PVT sections from the transverse ends AND cross member TB can be welded respectively to the front PAV anchor pieces.

[0013] This prior art process offers relatively simple machining (two machining operations with the tool axis along the vertical Z direction for each rear extension PB, and two machining operations for each transverse end ET of the cross member TB). However, for some cradles, it leads to a weakening of the lower flanges of its rear extensions PB, which can cause cracks to develop along the longitudinal X direction in the lower flanges AI. This results from the fact that machining the forward ends EV of the rear extensions PB necessitates adapting to the profile of the transverse ends ET of the cross member TB, and in particular, reducing the longitudinal extensions of the longitudinal bulkheads CL and the lower flanges AI at these forward ends EV to allow the passage and alignment of the transverse bulkhead CT of the cross member TB.However, this reduction in the longitudinal extension of the lower wings AI compared to that of the upper wings AS causes an unbalanced distribution of stresses between these lower wings AI and these upper wings AS, which can induce cracking of the lower wings AI.

[0014] To avoid this weakening, the position of the transverse partition CT on the crossmember TB could be offset. However, this position is dictated by the bearing surface of the steering fixing nut, which is defined in a hole in the crossmember TB located near a transverse end ET and adapted to accommodate a screw head; therefore, it is not possible to offset it.

[0015] The invention is therefore intended, in particular, to improve the situation.

[0016] To this end, it proposes a process, designed to enable the production of an aluminum cradle to be fitted to a vehicle, comprising: a first step in which two opposite transverse ends of a cross member are machined, comprising a transverse partition extruded in a transverse direction and two front ends respectively of two rear extensions extruded in a longitudinal direction perpendicular to the transverse direction and each comprising a longitudinal partition extended by upper and lower wings provided with holes defining an anchor point, in a vertical direction, and a second step in which machined rear parts of the transverse ends respectively are welded to the front ends.

[0017] This process is characterized by the fact that in its first stage, machining is performed: each front end by having a machining axis parallel to the vertical direction to define a first interface zone, then by having a machining axis parallel to the longitudinal direction in a lower part to define a second interface zone extending backwards from the first interface zone, and each transverse end by defining in an upper part of its rear part a third interface zone adapted to the first interface zone, then by having a machining axis parallel to the transverse direction in a lower part of its rear part to define a fourth interface zone adapted to the second interface zone.

[0018] With the lower wings and longitudinal bulkheads extended forward along the longitudinal direction, the docking between the cross member and the rear extensions is thus significantly improved, which allows for a better distribution of forces between the lower and upper wings at the forward ends of the rear extensions.

[0019] The method according to the invention may include other features which may be taken separately or in combination, and in particular: In a first embodiment, in its first step, each front end can be machined, on the one hand, with a machining axis parallel to the vertical direction and following a first path parallel to the transverse direction, to define the first interface zone, then with a machining axis parallel to the longitudinal direction and following a second path parallel to the transverse direction in the lower part to define the second interface zone, and, on the other hand, each transverse end with a third path contained in a plane perpendicular to the vertical direction and then contained in a plane perpendicular to the transverse direction, in the lower part of its rear part, to define the third interface zone.then, by having a machining axis parallel to the transverse direction and following a fourth path initially parallel to the vertical direction and then curved with respect to the vertical direction in the lower part of its rear section to define the fourth interface zone; in a second embodiment, in its first step, each front end can be machined, on the one hand, by having a machining axis parallel to the vertical direction and following a first path initially parallel to the transverse direction, then curved with respect to the transverse direction and finally again parallel to the transverse direction, to define the first interface zone, then by having a machining axis parallel to the longitudinal direction and following a second path parallel to the transverse direction in the lower part to define the second interface zone, and, on the other hand,each transverse end with a third path contained in a plane perpendicular to the vertical direction and then contained in a plane perpendicular to the transverse direction, in the lower part of its rear part, to define the third interface zone, then having a machining axis parallel to the transverse direction and following a fourth path initially parallel to the longitudinal direction and then parallel to the vertical direction and then curved with respect to the vertical direction to define the fourth interface zone; , in its first stage, after machining a transverse end with a machining axis parallel to the longitudinal direction and following a second path parallel to the transverse direction in the lower part to define the second interface zone, this transverse end can be machined at the level of an internal face of its upper wing with a machining axis parallel to the vertical direction and following a fifth path curved with respect to the longitudinal direction, in order to flatten part of the second interface zone at the level of this internal face; in its second stage a reinforcing add-on can be welded onto an external lower face of the longitudinal bulkhead and an external face of the lower wing of each rear extension, in the vicinity of its front end;In its second stage, machined front parts of the transverse ends can also be welded respectively to two extruded front anchor pieces along the transverse direction and comprising two vertical walls with holes defining another anchor point, along a longitudinal direction perpendicular to the transverse direction.

[0020] The invention also proposes an aluminum cradle, intended to equip a vehicle, and produced by implementing a manufacturing process of the type presented above.

[0021] The invention also proposes a vehicle, possibly of the automobile type, comprising an aluminum cradle of the type presented above.

[0022] For example, this vehicle may also include two wheel triangles, each comprising a front part attached to one of the front anchor pieces of the cradle, and a rear part attached to one of the rear extensions of the cradle.

[0023] Other features and advantages of the invention will become apparent upon examination of the detailed description below, and the accompanying drawings (obtained using CAD / CAM (“Computer-Aided Design / Computer-Aided Manufacturing”), hence the apparently discontinuous nature of some lines), on which: there figure 1 schematically illustrates, in a perspective view, an example of the construction of a prior art aluminum cradle, before the coupling of wheel assemblies, the figure 2 schematically illustrates, in a perspective view, the first machining phase of a front end of a rear extension of a cradle of the type illustrated on the figure 1 , there figure 3 schematically illustrates, in a perspective view, the second machining phase of a front end of a rear extension of a cradle of the type illustrated on the figure 1 , there figure 4 schematically illustrates, in a perspective view, a portion of the rear extension of the figures 2 et 3 after machining its front end, the figure 5 schematically illustrates, in a perspective view, the machining phase of a transverse end of a cross member of a cradle of the type illustrated on the figure 1 , there figure 6 schematically illustrates, in a perspective view, a portion of the crossbeam of the figure 5 after machining its transverse ends, the figure 7 schematically illustrates, in a perspective view, a first example of the first machining phase of a front end of a first example of the realization of a rear extension of a cradle according to the invention, the figure 8 schematically illustrates, in a perspective view, a first example of the second machining phase of a front end of a first example of the realization of a rear extension of a cradle according to the invention, the figure 9 schematically illustrates, in a perspective view, a portion of the rear extension of the figures 7 et 8 after machining its front end, the figure 10 schematically illustrates, in a perspective view, a first example of the second machining phase of a transverse end of a first example of the realization of a cross member of a cradle according to the invention, the figure 11 schematically illustrates, in a perspective view, a portion of the crossbeam of the figure 10 after machining its transverse ends, the figure 12 schematically illustrates, in a perspective view, a second example of the first machining phase of a front end of a second example of the realization of a rear extension of a cradle according to the invention, the figure 13 schematically illustrates, in a perspective view, a second example of the second machining phase of a front end of a second example of the realization of a rear extension of a cradle according to the invention, the figure 14 schematically illustrates, in a perspective view, a second example of the third machining phase of a front end of a second example of the realization of a rear extension of a cradle according to the invention, the figure 15 schematically illustrates, in a perspective view, a portion of the rear extension of the figures 12 à 14 after machining its front end, the figure 16 schematically illustrates, in a perspective view, a second example of the second machining phase of a transverse end of a second example of the realization of a cross member of a cradle according to the invention, the figure 17 schematically illustrates, in a perspective view, a portion of the crossbeam of the figure 16 after machining its transverse ends, and the figure 18 schematically illustrates, in a perspective view, part of a cradle according to the invention equipped with added reinforcing parts.

[0024] The invention aims in particular to propose a method for making an aluminum BA cradle with forces distributed on the AS and AI wings of the rear extensions PB and intended to equip a vehicle.

[0025] In what follows, the vehicle is considered, by way of non-limiting example, to be of the automobile type. This is, for example, a car. However, the invention is not limited to this type of vehicle. It relates in fact to any type of vehicle comprising an aluminum subframe intended to be part of a front suspension assembly and possibly to participate in the support of wheel wishbones and other equipment, such as, for example, the steering, the anti-roll bar, wheel mounts via the wishbone and anti-roll bar link attachment, exhaust support elements, or the soundproofing cover.

[0026] It is important to note that what differentiates a BA cradle according to the invention from the cradle of the prior art illustrated on the figure 1 These are essentially the respective front ends EV of its two rear extensions (right and left) PB and the two opposing transverse ends ET of its cross member TB. These significant differences result from the implementation of an embodiment method according to the invention, different from that of the prior art partially illustrated in the figures. figures 2 à 6 .

[0027] Therefore, once made, a cradle (in aluminium) BA, according to the invention, includes at least one cross member TB and two rear extensions (right and left) PB, as well as optionally two front anchor pieces or horns (right and left) PAV.

[0028] The process according to the invention comprises a first machining step followed by a second welding step, described later.

[0029] The TB cross member, according to the invention, comprises two transverse ends ET (opposite to each other) and a transverse partition CT extruded along the transverse direction Y. It is machined and intended to be installed in a vehicle along the transverse direction Y. This TB cross member comprises two ends opposite to each other and to each of which are fixedly attached a rear extension (or bracket) PB and optionally a front anchoring piece (or horn) PAV.

[0030] The rear anchoring of the BA cradle to the vehicle body is done via the two rear extensions PB, right and left. Each rear extension PB is extruded along the longitudinal direction X and machined to include a longitudinal partition CL extended by upper wings AS and lower wings AI, substantially horizontal and equipped with holes which define a third anchoring point PA3 (generally called E2), along the vertical direction Z, for example for the anchoring of a rear part of a wheel triangle, via a screw or a bolt.

[0031] In what follows and precedes, the terms "front" and "rear" refer to the front end of the vehicle. Therefore, a front element is oriented towards the front end of the vehicle, while a rear element is oriented towards the rear end of the vehicle.

[0032] The front anchoring of the BA cradle to the vehicle body can be achieved via the two front anchor pieces PAV, right and left. Each front anchor piece PAV is extruded along the transverse Y direction and comprises a lower part PI and an upper part PS that extend from each other.

[0033] Each lower section PI is fixedly attached to one of the two ends of the crossmember TB via weld beads and comprises two substantially parallel vertical walls PV with holes that define a first anchor point PA1 (or point E1), along the longitudinal direction X, for attaching a front section of a wheel (or suspension) triangle via a screw or bolt. Furthermore, each lower section PI may include holes TF for the fixed attachment, by screwing, of extensions designed to at least partially absorb shocks to the front of the vehicle.

[0034] Each upper part PS includes holes that define a second vertical anchor point PA2 (or point X2) and are intended to be passed through by a screw or bolt coupled to a part of the vehicle body.

[0035] Once the TB cross member, the PB rear extensions and the PAV front anchor pieces have been extruded in their respective directions, a manufacturing process according to the invention is implemented, which includes a first machining step and a second welding step.

[0036] In the first step, the two transverse ends ET of the TB cross member and the two front ends EV of the two rear extensions PB are machined. More precisely, and as illustrated (but not limited to) on the figures 7 à 9 And 12 à 15, we machine each front end EV of a rear extension PB with a machining axis that is parallel to the vertical direction Z to define a first interface zone ZI1, then with a machining axis parallel to the longitudinal direction X in a lower part to define a second interface zone ZI2 which extends rearward the first interface zone ZI1.

[0037] Furthermore, and as illustrated, but not limited to, on the figures 10 et 11 And 16 et 17 We begin by machining each transverse end ET of the cross member TB to define, in an upper part of its rear section PR, a third interface zone ZI3 adapted to the first interface zone ZI1, for joining in preparation for welding. To do this, we perform machining similar to that described previously with reference to the figures 5 et 6 that is to say by means of a tool having a machining axis placed parallel to the vertical direction Z with a path contained in the XY plane, then having a machining axis placed parallel to the transverse direction Y with a path contained in the XZ plane.

[0038] Then, we machine each transverse end ET of the cross member TB with a machining axis parallel to the transverse direction Y in a lower part of its rear part PR to define a fourth interface zone ZI4 adapted to the second interface zone ZI2, for apposition in preparation for welding.

[0039] In the second step of the process according to the invention, machined rear parts PR of the transverse ends ET of the cross member TB are welded respectively to the front ends EV of the two rear extensions PB. Alternatively, machined front parts PVT of the transverse ends ET of the cross member TB can be welded respectively to the front anchoring parts PAV.

[0040] Thanks to the invention, the lower wings AI and the longitudinal partitions CL are extended forward along the longitudinal direction X, compared to what is done in the prior art, which makes it possible to significantly improve the docking between the cross member TB and the rear extensions PB so that the forces are better distributed between the lower wings AI and upper wings AS at the level of the forward ends EV of the rear extensions PB.

[0041] The first step of the process according to the invention can be carried out in at least two ways described below.

[0042] In a first implementation of the first step, illustrated on the figures 7 à 11 , we can machine each front end EV in two phases and each transverse end ET in two phases.

[0043] In the first phase, we can begin by machining each front end EV with a machining axis parallel to the vertical Z direction and following a third path parallel to the transverse Y direction (arrow F1' of the figure 7 ), to define the first interface zone ZI1. Then, in a second phase, each front end EV can be machined with a machining axis parallel to the longitudinal direction X and following a second path parallel to the transverse direction Y in the lower part (arrow F2' of the figure 8 ) to define the second interface zone ZI2. The result of these two machining phases of a front end EV is illustrated on the figure 9 .

[0044] In a first phase, we can begin by machining each transverse end ET in the lower part of its rear section PR, with a third path contained in an XY plane perpendicular to the vertical direction Z and then contained in an XZ plane perpendicular to the transverse direction Y, to define the third interface zone ZI3. Then, in a second phase, we can then machine each transverse end ET in the lower part of its rear section PR, with a machining axis parallel to the transverse direction Y and following a fourth path, initially parallel to the vertical direction Z (arrow F3' of the figure 10 ) and then curved with respect to the vertical direction Z (arrow F4' of the figure 10 ) to remove the tool, to define the fourth interface zone ZI4. The result of these two machining phases of a transverse end ET is illustrated on the figure 11 .

[0045] In this first embodiment, the first machining phase of each front end EV is performed with the tool axis parallel to the vertical Z direction, as in the prior art. However, unlike the prior art, the second machining phase is performed with the tool axis parallel to the longitudinal X direction, which advantageously eliminates the need for a cutter radius. Furthermore, this allows the longitudinal partition CL of each rear extension PB to be advanced forward (in its lower part), thus better distributing the forces between the upper AS and lower AI wings.

[0046] Furthermore, in this first embodiment, the machining of each transverse end ET is carried out in two phases, unlike the prior art which requires only one. The second additional phase is performed on the transverse partition CT at the level of the two transverse ends ET, in order to allow the passage of each longitudinal partition CL of each rear extension PB (at the level of its forward end EV) because it (CL) is now further forward than in the prior art.

[0047] In a second embodiment of the first step, illustrated on the figures 12 à 17 , each front end EV can be machined in at least two phases and each transverse end ET in two phases.

[0048] In the first phase, we can begin by machining each front end EV with a machining axis parallel to the vertical Z direction and following an initial path parallel to the transverse Y direction (arrow F5' of the figure 12 ), then curved with respect to the transverse direction Y (arrow F6' of the figure 12 ), and finally again parallel to the transverse direction Y (arrow F7' of the figure 12 ), to define the first interface zone ZI1. Then, in a second phase, each front end EV can be machined with a machining axis parallel to the longitudinal direction X and following a second path parallel to the transverse direction Y (arrow F8' of the figure 13 ) in the lower part, to define the second interface zone ZI2.

[0049] As illustrated, but not limited to, on the figure 14 After the second phase, a third phase can also be carried out in which each front end EV is machined at an internal face of its upper wing AS, with a machining axis parallel to the vertical Z direction and following a fifth curved path relative to the longitudinal X direction (arrow F9' of the figure 14 ), in order to flatten part of the second interface zone ZI2 at the level of this inner face.

[0050] The result of these three machining phases of an EV front end is illustrated on the figure 15 .

[0051] In another initial phase, we can begin by machining each transverse end ET to define, in an upper part of its rear section PR, a third interface zone ZI3 adapted to the first interface zone ZI1, for joining in preparation for welding. To do this, we perform machining similar to that described previously with reference to the figures 5 et 6 that is to say by means of a tool having a machining axis placed parallel to the vertical direction Z with a path contained in the XY plane, then having a machining axis placed parallel to the transverse direction Y with a path contained in the XZ plane.

[0052] Then, in a second phase, each transverse end can be machined, with a machining axis parallel to the transverse Y direction and following a fourth path initially parallel to the longitudinal X direction (arrow F10' of the figure 16 ), then parallel to the vertical direction Z (arrow F11' of the figure 16 ), and then curved with respect to the vertical direction (arrow F12' of the figure 16 ), to define the fourth interface zone ZI4. The result of these two machining phases of a transverse end ET is illustrated on the figure 17 .

[0053] In this second embodiment, the first machining phase of each front end EV is still performed with the tool axis parallel to the vertical Z direction, but with a different path to allow for further forward advancement of each longitudinal partition CL of each rear extension PB (in its lower part). Then, the second machining phase is performed with the tool axis parallel to the longitudinal X direction, which advantageously eliminates the need for a cutter radius. Furthermore, a third phase can be added to rework the machining radius resulting from the first phase. Without this third phase, surfacing the inner face during the first phase would require using a smaller cutter radius and performing multiple passes, which is more expensive and time-consuming.

[0054] It should be noted, as illustrated (but not limited to) on the figure 18that in the second step, when necessary, a reinforcing piece PRR can be welded to an external lower face of the longitudinal bulkhead CL and an external face of the lower wing AI of each rear extension PB, near its forward end EV. This further improves the resistance of the rear extensions PB to stress.

Claims

1. Method for producing an aluminum cradle (BA) intended to be fitted to a vehicle, said method comprising i) a first step in which two transverse ends (ET) opposite one another are machined from a cross member (TB) comprising a transverse partition (CT) extruded a transverse direction and both ends before (EV) of two rear prolong respectively (PB) extruded in a longitudinal direction perpendicular to said transverse direction and comprising each partition a longitudinal (L) extended by upper flanges (AS) and lower (AI) provided with holes defining an anchor point (PA3), in a direction vertical, and ii) a second step in which it welds rear portions (PR) machined of said transverse ends (ET) respectively to said front ends (EV), characterized in that e in said first step is machined a) each front end (EV) having a machining axis parallel to said vertical direction to define a first interface zone (ZI1), then having a machining axis parallel to said longitudinal direction in a lower part to define a second interface zone (ZI2) extending rearwardly said first interface zone (ZI1), and b) each transverse end (ET) to define in an upper part of its rear part (PR) a third interface zone (ZI3) adapted to said first interface zone (ZI1) then having a machining axis parallel to said transverse direction in a lower part of its rear part (PR) to define a fourth interface zone (ZI4) adapted to said second interface zone (ZI2).

2. Method according to claim 1, characterized in that in said first step a) each front end (EV) is machined having a machining axis parallel to said vertical direction and following a first path parallel to said transverse direction, to define said first interface zone (ZI1), then having a machining axis parallel to said longitudinal direction and following a second path parallel to said transverse direction in said lower part to define said second interface zone (ZI2), and b) each transverse end (ET) with a third path contained in a plane perpendicular to said vertical direction and then contained in a plane perpendicular to said transverse direction, in said lower part of its rear part (PR), to define said third interface zone (ZI3), then having a machining axis parallel to said transverse direction and following a fourth path initially parallel in said vertical direction and then curved with respect to said vertical direction in said lower part of its rear part (PR) to define said fourth interface zone (ZI4).

3. Method according to claim 1, characterized in that in said first step a) each front end (EV) is machined by having a machining axis parallel to said vertical direction and by following a first path initially parallel to said transverse direction and then curved with respect to said transverse direction and finally again parallel to said transverse direction, to define said first interface zone (ZI1), then having a machining axis parallel to said longitudinal direction and following a second path parallel to said transverse direction in said lower part to define said second interface zone (ZI2), and b) each transverse end (ET) with a third path contained in a plane perpendicular to said vertical direction and then contained in a plane perpendicular to said transverse direction, in said lower part of its rear part (PR), then having a machining axis parallel to said transverse direction and following a fourth path initially parallel to said longitudinal direction then parallel to said vertical direction and then curved with respect to said vertical direction to define said fourth interface zone (ZI4).

4. Method according to claim 3, characterized in that in said first step, after having machined a transverse end (ET) having a machining axis parallel to said longitudinal direction and following a second path parallel to said transverse direction in said part bottom to define said second interface zone (ZI2) is machined this transverse end (ET) at an inner face of the upper wing (AS) having a machining axis parallel to said vertical direction and following a fifth path curved with respect to said longitudinal direction, in order to flatten part of said second interface zone (ZI2) at the level of this internal face.

5. Method according to one of claims 1 to 4, characterized in that in said second step welding an insert reinforcement (PRR) on an outer side bottom of said longitudinal partition (CL) and an outer face of said lower wing (AI) of each rear extension (PB), in the vicinity of its front end (EV).

6. Method according to one of claims 1 to 5, characterized in that in said second step, machined front parts (PVT) of said transverse ends (ET) respectively to two front anchoring parts (PAV) extruded in said direction are also welded transverse and comprising two vertical walls (PV) provided with holes defining another anchor point (PA1), in a longitudinal direction perpendicular to said transverse direction.

7. Aluminum cradle (BA), intended to equip a vehicle, characterized in that it is produced by a implementing the production method according to one of the preceding claims.

8. Vehicle characterized in that it comprises a cradle to aluminum (BA) according to claim 7.

9. Vehicle according to claim 8, characterized in that it comprises two wheel triangles each comprising a front part secured to one of said front anchoring parts (PAV) of said aluminum cradle (BA), and a rear part secured to one of said rear extensions (PB) of said aluminum cradle (BA).

10. Vehicle according to claim 8 or 9, characterized in that it is of the automobile type.