Steel reinforced shield beam

Abstract

Steel Reinforced Shield Beam\nSummary\nRamp (1) for a shield beam which includes the following: \n- an outer beam (2) extending in the transverse direction with a main beam portion (3) comprising an upper beam wall (12), a lower beam wall (14) and a front beam wall (16), which together define an inner beam volume (17) opening in the rearward direction,\n- a reinforcement element (4) defining a reinforced region (24) of the outer beam (2), which is inside a portion of the inner volume of said beam (17) and has a cross-sectional area, and defining an inner reinforced volume (25) opening in the rearward direction,\n- a closing plate (6) having at least It closes a part of the internal volume of the beam (17), \nwhere the cross-section of the reinforcing element (4) has a shape that does not correspond to the shape of the external beam (2) in the reinforced area (24)\n\n\nFigure: 4

Description

Steel reinforced shield beam The present invention relates to a ram for a bumper beam of an automobile vehicle. The invention further relates to a method for producing such a ram. The bumper beam ram is located at the front and / or rear of the vehicle and is usually attached to the crash boxes, usually by bolting. The crash boxes themselves are mounted on the vehicle structure. In the event of a frontal or rear-end collision, the ram is the first transverse element of the vehicle to come into contact with the obstacle. In the event of a high-speed collision, the ram has the function of transferring the load to the vehicle's crash management system. In the event of a low-speed collision, the crash boxes, on which the ram is mounted, have the function of absorbing the crash energy while protecting the rest of the vehicle structure. In all cases, the ram is intended to deform but not crack during the collision. Thus, the ram for the bumper beam needs to have sufficient strength to transfer the crash load to the vehicle's crash management system, while simultaneously exhibiting sufficient ductility at the point of impact to deform without forming cracks. In order to ensure the proper behavior of the RAM during a crash, several standardized tests have been defined by regulatory consortia. For example, the Research Council for Automotive Repair (RCAR) defines a bumper test and a low-speed structural crash test. RAM is also involved in other tests that involve the entire vehicle, such as the "50 km / h rigid barrier frontal crash" of Euro NCAP (New Car Assessment Program) and IIHS (Insurance Institute for Highway Safety), also known as the full frontal crash test. In addition, car manufacturers also have their own testing procedures to further evaluate the rollover. Such tests are not standardized and are not publicly available. However, it is known that most car manufacturers have defined a test known as an impact test, in which the vehicle is hit at a low speed, for example about 10 km / h, against a rigid pillar located in the middle of the width of the vehicle. Such a test is intended to simulate small impacts during low-speed maneuvering of the vehicle. During such a test, the central part of the ram needs to have sufficient ductility at the point of impact to deform without cracking under the local load applied by the column during the impact. On the other hand, considering (for example) a full frontal crash test, the entire width of the ram needs to have sufficient mechanical strength to not fail under the very high load applied by the barrier and to transfer the impact energy to the vehicle's crash management system. It is known from prior art that in the design of the ram shape, one or more beads are considered to increase the ram's resistance to crash compressive loads by delaying the onset of buckling. It is also known from the prior art that such a frame is constructed using at least one outer beam and a reinforcing element inserted into the central portion of the outer beam, said reinforcing element having a cross-sectional area having a shape that substantially corresponds to the shape of the outer beam. The reinforcing element is used to increase the energy absorption capacity of the shield beam in the central portion, which is the area that experiences the greatest amount of stress (for example) in a column impact test. However, having a matching cross-sectional shape between the outer beam and the reinforcement element imposes a limitation on the design of the internal reinforcement shape, which creates problems in the manufacturing process of the outer beam and the reinforcement element, as well as problems in the assembly process of said outer beam and said internal reinforcement. In fact, because the reinforcement shape matches the shape of the outer beam, the assembly of both parts requires very high geometric tolerances of said parts, since both parts must be in contact with each other over a large amount of their surface. When manufacturing such parts with advanced high-strength steel (for example), it is known that it is difficult to achieve a very high geometric tolerance due to springback. Therefore, the manufacturing process of such parts requires special, costly and time-consuming steps to achieve the necessary geometric accuracy. The assembly step also requires special measures (for example) to clamp both parts together with high strength. In addition, the shape of the reinforcement element is not optimal in terms of energy absorption capacity. One of the objectives of the present invention is to overcome these limitations by providing a ram for a shield beam that is optimal in terms of energy absorption and does not require special arrangements during the manufacturing process. To this end, the invention relates to a ram for a bumper beam for an automotive vehicle, comprising: - an outer beam extending in the transverse direction with a main beam section comprising an upper beam wall, a lower beam wall and a front beam wall connected to the upper beam wall and the lower beam wall, said upper beam wall, lower beam wall and front beam wall together defining an internal volumetric opening of the beam in the rear direction opposite the front beam wall, - a reinforcing element defining a reinforced area of ​​the outer beam, located within a portion of the internal volume of said beam and having a cross-section defining an internal volumetric opening in the rear direction, - A closing plate, which closes at least part of the internal volume of the beam. where the cross-section of the reinforcing element has a shape that does not match the shape of the outer beam in the reinforced area, wherein the reinforcing element comprises at least one upper reinforcing wall connected to a primary intermediate reinforcing wall by an upper connecting wall, said primary intermediate reinforcing wall is connected to a secondary intermediate reinforcing wall by a central connecting wall, and said secondary intermediate reinforcing wall is connected to a lower reinforcing wall by a lower connecting wall, said upper and lower connecting walls are positioned against the front beam wall of the outer beam, and said central connecting wall is positioned against the opening face of the outer beam. Because the cross-section of the outer beam and the reinforcing element have a different shape and do not coincide with each other in the reinforced area, it is possible to design them separately, taking into account the specific requirements of each component. In particular, it is possible to design the reinforcing element to have an M-shaped cross-section that opens towards the rear, which is an optimized shape to optimize energy absorption during a crash and optimizes the manufacturing costs of the reinforcing element. However, it is not necessary to perform costly measurements to ensure very high geometric tolerances between the outer beam and the reinforcing element, and to assemble these components together. According to other optional features of the ROM according to the invention, individually or in any possible technical combination: - The closing plate completely closes the reinforced internal volume, - The width of the reinforced area along the transverse direction is less than the width of the outer beam along the transverse direction, - The width of the reinforced area along the transverse direction is between 30% and 80% of the width of the main beam section of the outer beam along the said transverse direction, - The width of the binding plate along the transverse direction is between 50% and 100% of the width of the main beam section of the outer beam in the said transverse direction, - The reinforcing element includes at least one of the reinforcing walls, forming an angle between 75° and 105° with the front beam wall of the outer beam, - At least the central connecting wall is next to the closing plate, - The said central connecting wall and the closing plate are connected to each other, - The reinforcing element has a constant cross-section along the transverse direction, - The outer beam includes an upper beam flange and a lower beam flange, said beam flanges extend on each side of the upper beam wall and the lower beam wall of said outer beam, the reinforcing element includes an upper reinforcing flange and a lower reinforcing flange, said reinforcing flanges are connected to said beam flanges in the reinforcing region. - The closing plate is connected to the reinforcement flanges and to the beam flanges and in the reinforcement area and is connected to the said beam flanges and only outside of the said reinforcement area. - The closure plate includes at least one opening outside the reinforcement area and does not include any openings inside said reinforcement area, - The outer beam is a hot-pressed steel sheet, - The outer beam is a hot-pressed welded steel plate comprising a central beam section and two side beam sections extending on each side of said central beam section in the transverse direction, the width of the central beam section in the transverse direction being equal to or greater than the width of the reinforcement area in the transverse direction, - The central beam section has a high failure ductility compared to the side beam sections, - The central beam section has a failure ductility of at least 0.6 and a maximum bending angle of at least 75°, - The outer beam has an ultimate tensile strength of at least 950MPa, - The reinforcing element has an ultimate tensile strength of at least 500 MPa, and - The closing plate has an ultimate tensile strength of at least 500MPa. The present invention also provides a method for producing a ROM (as described above) comprising the following steps: - Provision of an external beam, - Provision of a reinforcing element, - Provision of a closing page, - connecting the reinforcing element to the outer beam in a reinforced area of ​​said outer beam, - Connection of the closing plate to the reinforcing element and to the outer beam in the reinforced area. According to other optional features of the method according to the invention, individually or in any possible technical combination: - The closing plate is additionally connected to the outer beam outside the reinforced area, - The outer beam is made from a hot-pressed steel sheet, - The outer beam is hot-pressed from a welded or rolled plate consisting of a central plate section and two side plate sections extending transversely from both sides of the central plate section, and - The reinforcing element is formed by roll forming a steel plate. Other aspects and advantages of the invention will become apparent upon reading the following description, given by way of example, and with reference to the accompanying drawings, in which: - Figure 1 is a general front perspective view of a ram according to an example of the invention, - Figure 2 is a rear perspective view of the overall frame of Figure 1, - Figure 3 is a rear view of the central part of the ram of Figure 1, - Figure 4 is a cross-sectional view along the IV-IV axis of Figure 1, - Figure 5 is a front view of a plate for forming the outer beam of a ram according to an example of the invention. In the following description, the terms "up", "down", "front", "rear", "transverse" and "longitudinal" are defined according to the usual directions of a mounted vehicle. More specifically, the terms "up" and "down" are defined according to the height direction, the terms "front", "rear" and "longitudinal" are defined according to the front / rear direction of the vehicle, and the term "transverse" is defined according to the width of the vehicle. "Substantially parallel" "Substantially perpendicular" means a direction that can deviate from the parallel or vertical direction by no more than 15°. More specifically, the term "strain at failure", also known as "failure ductility", and the term "critical bending angle", also known as "maximum bending angle", are defined by the criterion for strain at failure and the criterion for critical bending angle in: Pascal Dietsch et al. in "Methodology to assess fracture during crash simulation: fracture strain criteria and their calibration", in Metallurgical Research Technology Volume 114, Number 6, 2017 The critical bending angle (also known as the maximum bending angle) defines the angle at which the first cracks are detected on the outer arc of a specimen deformed according to the VDA-238-100 standard. The failure strain (also known as the failure ductility) is the corresponding equivalent strain in the material at the point of deformation when the critical bending angle is reached. With reference to Figures 1 and 2, a frame 1 for a bumper beam of a motor vehicle is described. The frame 1 comprises an outer beam 2, a reinforcing element 4 and a closing plate 6. The frame is typically connected to the rest of the vehicle on either side of the outer beam 2, for example by a set of two crash boxes (not shown in the drawings). During a frontal collision in the case of a front frame 1 or during a rear collision in the case of a rear frame 1, the frame 1 is subjected to a compressive impact force F, as shown in Figures 1, 2 and 4. The outer beam 2 extends in the transverse direction and comprises a main beam section 3 and two end beam sections 5 extending in the transverse direction from each side of the main beam section 3. The shape of the outer beam 2 at the end sections 5 may be flat or any other shape suitable for assembling the cross beam 1 to the rest of the vehicle body, and in particular to the crash boxes. The main beam section 3 is used to absorb the energy of the compressive impact force F and to resist penetration by the vehicle by transmitting the compressive impact force F to the vehicle crash management system. The main beam section 3 comprises an upper beam wall 12 and a lower beam wall 14, each of which is substantially perpendicular to the height direction of the vehicle, and a front beam wall 16, which connects said upper and lower beam walls and is substantially perpendicular to said upper and lower beam walls 12 and 14. When the ram 1 is mounted on the vehicle, the upper and lower beam walls 12, 14 are, for example, substantially horizontal.According to one variant, the upper and lower beam walls extend from the front beam wall 16 towards the rear of the frame 1 in diverging directions. The upper beam wall 12, the lower beam wall 14 and the front beam wall 16 together define an internal beam volume 17, which opens in a rearward direction opposite the front beam wall 16. In the case of the front ram, the rearward direction is towards the rear of the vehicle, and in the case of the rear ram, the rearward direction is towards the front of the vehicle. According to a specific example, outer beam 2 has an ultimate tensile strength of 950MPa in order to withstand high stresses during a crash. According to a specific example, which can be seen in Figures 1 to 3, the main beam section further comprises a central beam section 8 and two side beam sections 10 extending in each direction from the central beam section 8 in the transverse direction, said central beam section 8 having a higher failure ductility than said side beam sections 10. In this example, the central beam section 8 advantageously adapts to the concentration of very high stress at the center of the ram 1 during the column impact test by deforming without cracking thanks to its failure ductility, while the side beam sections 10 resist deformation, thereby ensuring the physical integrity of the ram during such a column impact test or during a high-speed impact test. According to one example, the outer beam 2 is made of a welded and hot-pressed plate. The outer beam 2 is, for example, a press-hardened steel part. More specifically, the central beam part 8 is made, for example, of a press-hardened steel having a carbon content of between 0.06 wt.% and 0.1 wt.% and a manganese content of between 1.4 wt.% and 1.9 wt.%. Even more specifically, the steel composition of the central beam part 8 may additionally comprise Nb, Ti, B as alloying elements. The central beam part 8 is made, for example, of Ductibor 1000®, which has a failure ductility of at least 0.6, a maximum bending angle of at least 75°, an ultimate tensile strength of above 1000 MPa and a yield strength of between 700 and 950 MPa. Each side beam section 10 is made, for example, from a press-hardened steel having a tensile strength greater than 1300 MPa. According to one example, the steel composition of the side beam sections 10, for example, includes, in weight percent, the following: 0.20% ≤ C ≤ 0.25%, 1.1% ≤ Mn ≤ 1.4%, 0.15% ≤ Si ≤ 0.35%, ≤ Cr ≤ 0.30%, 0.020% ≤ Ti ≤ 0.060%, 0.020% ≤ Al ≤ 0.060%, S ≤ 0.005%, P ≤ 0.025%, 0.002% ≤ B ≤ 0.004% The iron residue and unavoidable impurities are due to the details. With this composition range, the tensile strength of the side beam sections 10, after being press-hardened, is between 1300 and 1650 MPa. According to another example, the steel composition of the side beam sections 10, for example, includes, in weight percent: 24% ≤ C ≤ 0.38%, 0.40% ≤ Mn ≤ 3%, 0.10% ≤ Si ≤ 0.70%, 0.015% ≤ Al ≤ 0.070%, Cr ≤ 2%, 0.25% ≤ Ni ≤ 2%, 0.015% ≤ Ti ≤ 0.10%, Nb ≤ 0.060%, 0.0005% ≤ B ≤ 0.0040%, 0.003% ≤ N ≤ 0.010%, S ≤ 0.005%, P ≤ 0.025%, % The iron residue and unavoidable impurities are due to the details. With this composition range, the tensile strength of the side beam sections 10, after being press-hardened, is greater than 1800 MPa. For example, the side beam sections 10 are made of Usibor 1500® or Usibor 2000®. According to a specific example, which can be seen in Figures 1 to 4, the main beam portion 3 of the outer beam 2 further comprises an upper beam flange 20 extending in the transverse direction along the rear end of the upper beam wall 12 and a lower beam flange 22 extending in the transverse direction along the rear end of the lower beam wall 14. The rear ends of the upper and lower beam walls 12, 14 each extend in the rear direction opposite the front beam wall 16. Such upper and lower beam flanges 20 and 22 can be usefully used for assembling the various parts of the cross beam 1 as will be explained in more detail below. According to another specific example, as shown in Figure 1, the front beam wall 16 includes grooves 18, each extending in the transverse direction along at least a portion of the width of the outer beam 2 and located one above the other in the height direction. Said grooves 18 can advantageously increase the resistance of the outer beam 2 under compressive loading by delaying the onset of buckling, since their geometry includes elements that are substantially parallel to the compressive impact force F during a crash. The reinforcing element 4, shown in Figures 1 to 4, extends into a portion of the inner volume of the beam 17, which defines a reinforced region 24 of the outer beam 2, and defines a reinforced inner volume 25 in the inner volume of the beam 17 and opens towards the rear. The reinforcing element 4 is a distinct part of the outer beam 2 and is connected to said outer beam 2 in the reinforced region 24. In a particular example, the reinforced region 24 extends over at least a portion of the central beam portion 8 of the outer beam 2. Advantageously, the reinforcing element 4 is used to increase the amount of energy absorbed in the reinforced region 24 located in the central beam portion 8 of the outer beam 2, which is the region exposed to the highest amount of stress during the column impact test. In another particular example, in which the central beam portion 8 has a higher failure ductility than the side beam portions 10, thereby preventing the formation of cracks during low-speed impacts at the center of the ram 1, but creating a weakness in the mechanical strength of said central beam portion 8, the reinforcing element 4 is also used to increase the mechanical strength of the reinforced region 24 during a high-speed crash, such as a full-frontal crash test. In a particular example, the reinforced region 24 has a smaller width along the transverse direction than the width of the outer beam 2. In another particular example, the width of the reinforced region 24 is between 30% and 80% of the width of the main beam portion 3 of the outer beam 2. For example, the width of the reinforced region 24 is substantially equal to the width of the central beam portion 8, and the focus of the reinforced region 24 coincides with the central beam portion 8. The minimum width of the reinforced region 24 is defined by the need for the reinforcing element 4 to act effectively in absorbing energy at the center of the frame 1 during a crash. On the other hand, the maximum width of the reinforcing element 4 is defined by the need to minimize the amount of material, in order to minimize manufacturing costs and minimize the weight of the frame 1. The cross-section of the reinforcing element 4, in a plan including the height direction and the longitudinal direction, has a shape that is different from and does not correspond to the shape of the outer beam 2 in the reinforced area 24, as shown in Figure 4. Advantageously, this means that the cross-section of the reinforcing element 4 can be optimized to absorb as much energy as possible during a crash, independently of the shape of the outer beam 2.More specifically, when the outer beam 2 includes grooves 18, the shape of the reinforcing element 4 can be independent of the shape of said grooves 18. The reinforcement element 4 comprises at least four reinforcement walls 24, at least one of which forms an angle between 75° and 105° with the front beam wall 16 of the outer beam 2. For example, one of the reinforcement walls 27 forms an angle of 90° with the general direction of the front beam wall 16. According to one example, all of the reinforcement walls form an angle between 75° and 105° with the beam wall 16 of the outer beam 2. The reinforcement walls 27 are arranged to deform in the event of an impact against the outer beam 2, which contributes to increasing the energy absorbed during the accident thanks to the orientation of the reinforcement walls 27 which is essentially parallel to the direction of the compressive impact force F. In order to have an optimal energy absorption, in concentrating the reinforcing walls 27 in a part of the reinforced internal volume 25, the reinforcing walls 27 have a length l, in a direction parallel to the compressive impact force F, which is as close as possible to the distance d between the front beam wall 16 and the rear end of said part of the reinforced internal volume 25 in said direction, as shown in Figure 4.The length l of the reinforcing walls 27 is, for example, between 50% and 100% of the distance d between the front beam wall 16 and the rear end of the part of the reinforced internal volume 25 in which said reinforcing walls 27 extend. It should be noted that in order to take into account the geometric tolerances associated with the manufacturing process of the parts, it is preferable that in the design of the parts, there is a minimum gap of at least 1 mm between the distance d and the length l. Such that the distance d is at least greater than the length l in the mounted vehicle. In fact, if the distance d and the length l are designed to be exactly equal, there is a risk that, due to dispersion in the manufacturing process, the effective length l of the reinforcing walls 27 of the fabricated reinforcing element 4 will be exactly greater than the effective length d between the front wall 16 and the rear end of the reinforced inner volume 25 of the fabricated outer beam 2, in which case it will not be possible to fit the reinforcing element 4 into the reinforced inner volume 25.As shown in Figure 4, the reinforcement element 4 comprises a plurality of reinforcement walls 26, 28, 32 and 36, and more particularly at least one upper reinforcement wall 26 connected to a primary intermediate reinforcement wall 28 by an upper connecting wall 30, said primary intermediate reinforcement wall 28 is connected to a secondary intermediate reinforcement wall 32 by a central connecting wall 34 and said secondary intermediate reinforcement wall 32 is connected to a lower reinforcement wall 36 by a lower connecting wall 38, said upper and lower connecting walls 30 and 38 are positioned opposite the front beam wall 16 of the outer beam 2 and said central connecting wall 34 is positioned opposite the rear side of said outer beam 2, opposite the front beam wall 16. In other words, the reinforcing element 4 has an M-shaped cross-section that opens towards the rear. Advantageously, such a reinforcing element 4 comprises at least four reinforcing walls 26, 28, 32, 36 substantially parallel to each other and with a compressive impact force F.It should be noted that the greater the number of reinforcing walls 26, 28, 32, 36, the higher the energy absorption in the event of an accident. It is understood that when the reinforcing element 4 comprises more than four reinforcing walls, the reinforcing element 4 will also comprise the same number of intermediate reinforcing walls facing the front beam wall 16 and the same number of central reinforcing walls 34 facing the rear end of the reinforced area 24, which are necessary to connect the reinforcing walls to each other. The reinforcing walls may have a length l, all in a direction parallel to the compressive impact force F. In a variant, the reinforcing walls have different lengths l which should be arranged as close as possible to the distance d between the front beam wall 16 and the rear end of the reinforced internal volume parts 25 in which said reinforcing walls extend. When the RAM 1 is mounted on the vehicle, the reinforcing walls, for example, extend in essentially horizontal planes. In a particular example, the reinforcing element 4 has a constant cross-section extending along the transverse direction. Advantageously, this enables the reinforcing element 4 to be manufactured using a highly efficient and cost-effective process, which will be explained in detail later. In a particular example, the reinforcement element 4 includes an upper wing 40 extending transversely along the rear end of the upper reinforcement wall 26 and a lower wing 42 extending transversely along the rear end of the lower reinforcement wall 36. The rear ends of the upper and lower reinforcement walls 26 and 36 each extend rearwardly opposite the front beam wall 16. Such upper and lower reinforcement wings 40 and 42 can be usefully used for assembling various components of the frame 1, as will be described in detail below. The fact that the reinforcing element 4 has an M-shaped cross-section opening towards the rearward direction makes it possible to have four reinforcing walls, which ensures maximum energy absorption during the accident, and makes it possible to connect the outer beam wings by connecting the upper and lower reinforcing wings, which extend along the rear ends of the upper and lower reinforcing walls, to the outer beam wings, which will be explained in detail below. In another specific example, the reinforcing element 4 has an ultimate tensile strength of at least 500 MPa. Advantageously, the reinforcing element 4 has a high strength value in order to effectively absorb energy during a crash. The closing plate 6, shown in Figures 2, 3 and 4, is connected to at least the outer beam 2. The closing plate 6 has a width in the transverse direction which is at least equal to the width of the reinforced area 24. During an accident, as a result of the compressive impact force F applied to the front beam wall 16, the outer beam 2 has a tendency to open itself in the vertical direction, in other words, the compressive impact force F causes the angle between the upper beam wall 12 and the front beam wall 16 to increase and the angle between the lower beam wall 14 and the front beam wall 16 to increase. In other words, in the event of an impact, the upper and lower beam walls 12 and 14 tend to move away from each other in diverging directions. Such opening of the outer beam 2 has the effect of reducing the amount of energy absorbed by the ram 1 because the upper and lower walls 12 and 14 are inclined in the direction of the compressive impact force F, rather than being parallel to the compressive impact force F.In other words, the energy absorbed by the non-bending movement of the outer beam 2 by the compressive impact force F, when said compressive impact force F is capable of opening the slit of said outer beam 2, is much less than the energy absorbed by the resistance to the compressive impact force F of the lower and upper walls 12 and 14, when said walls 12 and 14 remain substantially parallel to the compressive impact force F during the accident. Advantageously, the closing plate 6 connected to the outer beam 8 counteracts this opening effect of the compressive impact force F and ensures that the upper and lower walls 12 and 14 remain substantially parallel to the compressive impact force F during the accident. According to one example, the width of the closing plate 6 along the transverse direction is between 50% and 100% of the width of the main beam portion 3 of the outer beam 2 along said transverse direction to provide at least a sufficient connection surface between the closing plate 6 and the outer beam 2. In a particular embodiment, the closing plate 6 closes the reinforced area 24 over its entire length. In other words, the closing plate 6 closes the internal volume of the beam 17 in the rearward direction at least in the reinforced area 24 and has no opening in said reinforced area. In this case, during an accident, the reinforcing element 4 is pushed against the closing plate 6, which eventually, if the compressive impact force F is sufficiently high, touches the closing plate 6. Advantageously, the contact between the reinforcing element 4 and the closing plate 6 and the subsequent breakage of the reinforcing element 4 on the closing plate 6 increases the amount of energy absorbed by the ram 1. In a particular example, before the ram 1 is subjected to the compressive impact force F, the reinforcing element 4 is located adjacent to the closure plate 6 at least in part of the central connecting wall 34 of the reinforcing element 4. In fact, this triggers the breaking effect of the reinforcing element 4 on the closure plate 6 described above right at the beginning of the accident and, therefore, further increases the amount of energy absorbed by the ram 1 during the accident. According to an example, when the reinforcing element 4 comprises more than one central connecting wall 34, the reinforcing element 4 may be adjacent to the closure plate 6, at least in part of one or more of said central connecting walls 34. In a particular embodiment, the reinforcing element 4 and the closing plate 6 are connected to each other at least in part of a central connecting wall 34 of the reinforcing element 4. The reinforcing element 4 and the closing plate 6 can be connected by welding or screwing or any other possible fastening method. Advantageously, when the closing plate 6 and the reinforcing element 4 are connected in a central connecting wall 34, said central connecting wall 34 cannot slide on the closing plate under the influence of the compressive impact force F. Therefore, the reinforcing element 4 necessarily slides on the closing plate 6, thereby providing greater rigidity in the increase in energy absorption resulting from the interaction between the closing plate 6 and the reinforcing element 4. Furthermore, since the reinforcing element 4 is already connected to the outer beam 2, connecting a central connecting wall 34 of said reinforcing element 4 to said closing plate 6 advantageously additionally prevents the outer beam 2 from opening under the influence of the compressive impact force F.According to one example, when the reinforcing element 4 comprises more than one central connecting wall 34, the reinforcing element 4 may also be connected to the closure plate 6 at least in part of one or more of said central connecting walls 34. In a preferred embodiment, the closing plate 6 includes at least one opening 44 outside the reinforced area 24, and the inside of the reinforced area 24 is completely closed, as shown in Figures 2 and 3. Advantageously, this will reduce the weight of the frame 1, while ensuring good cooperation between said closing plate 6 and the reinforcing element 4 during an accident and a sufficient contact surface between the closing plate 6 and the outer beam 2. In another preferred embodiment, the closure plate 6 has an ultimate tensile strength of at least 500 MPa, to advantageously resist the opening effect of the compressive impact force F and to advantageously cooperate with the reinforcing element 4 to increase the amount of energy absorbed. It should be noted that, as is already known, the outer beam 2 may have a curved shape along the transverse direction. In this case, the reinforcing element 4 and the closing plate 6 may also have a corresponding curved shape along the transverse direction. The frame for a shield beam described above, consisting of an outer beam and a reinforcing element with a different shape, which does not match the shape of the outer beam, has several advantages, among which is the freedom of choice in the design of the shape of the outer beam and the reinforcing element, which allows the shape of each component to be individually optimized according to their specific requirements, such as energy absorption, cost reduction and weight. Another advantage of the said frame is the freedom to choose the most appropriate manufacturing process for the said outer beam and the said reinforcing element according to the functional requirements of each part as well as considering the efficiency and cost of the manufacturing process. In addition, having different and mismatched cross-sections between the outer beam and the reinforcing element allows for easy assembly of both parts, as you will see in the description of the frame manufacturing method explained above. The method includes a step of providing an outer beam 2. For example, the outer beam 2 is made by hot pressing a steel plate 46. In a specific embodiment of the present invention shown in Figure 5, the outer beam 2 is made by hot pressing a welded plate having a central plate portion 48 and two side plate portions 50 extending transversely in each direction of said central plate portion 48. After hot pressing, the central plate portion 48 and the side plate portions 50 correspond to a central beam portion 8 and two side beam portions 10, respectively. For example, as described above, said central beam portion 8 is made of Ductibor 1000® and said side beam portions 10 are made of Usibor 1500®. Advantageously, this makes it possible to produce an outer beam 2 comprising a central beam section 8 having a high failure ductility and two side beam sections 10 having a very high mechanical strength, in a single step.Furthermore, by selecting a steel grade with a very high mechanical strength for the side beam sections 10, it is possible to achieve a high mechanical strength for the side beam sections 10 with a low steel thickness, thereby contributing to minimizing the weight of the frame 1. According to a variant, the outer beam 2 is made from a hot press of a rolled welded plate. The method further comprises a step of providing a reinforcing element 4. In a particular example, said reinforcing element 14 has a constant cross-section extending along the transverse direction. In this case, the reinforcing element 4 is made, for example, by roll forming a steel plate, which is a high-efficiency and low-cost forming process. This method further includes a step of providing a sealing plate 6. The method further comprises the step of attaching the reinforcing element 4 to the outer beam 2 in the reinforced region 24 of said outer beam 2. For example, the reinforcing element 4 is attached to the outer beam 2 by securing the upper reinforcing wing 40 to the upper beam wing 20 and by securing the lower reinforcing wing 42 to the lower beam wing 22, by welding, mechanical bonding or any other fastening technology. Advantageously, since the wings 20, 22, 40 and 42 correspond to substantially flat regions of the parts that are not deformed or only slightly deformed during the forming process of the parts, it is easy to ensure good geometric accuracy in these regions and therefore it is easy to ensure good contact between the parts in the wing regions during the assembly step. The method further includes the step of attaching the fastening plate 6 to the reinforcement element 4 in the reinforced area 24. For example, the fastening plate 6 is secured to the reinforcement element 4 by welding, mechanical bonding, or any other possible securing technology to the upper and lower reinforcement wings 40 and 42. In a particular example, the above-described step of assembling the reinforcement element 4 to the outer beam 2 and the step of assembling the fastening plate 6 to the reinforcement 4 in the reinforced area 24 are performed in one step, using the wings 20, 22, 40, and 42 as the connection areas between the three pieces in the reinforced area 24, for example, by multi-layer welding. Advantageously, combining two assembly steps into a single step reduces assembly time, thereby increasing efficiency and reducing process costs. In a particular example, the closing plate 6 is additionally connected to the outer beam 2 outside the reinforced area 24. For example, the closing plate 6 is connected to the upper and lower beam flanges 20 and 22 outside the reinforced area 24. In a specific example, the closure plate 6 is connected to at least one intermediate connecting wall 34 of the reinforcement element 4. In another specific example, the process of forming the closure plate 6 includes forming at least one opening 44 in said closure plate 6, outside the reinforced region 24. In another specific example, the central beam part 8 is made of Ductibor 1000® with a thickness between 1.3mm and 1.7mm, for example 1.5mm, the side beam parts 10 are made of Usibor 1500® with a thickness between 0.8mm and 1.2mm, for example 1.05mm, the reinforcing element 4 is made of steel with an ultimate tensile strength above 950MPa and with a thickness between 0.5mm and 0.9mm, for example 0.7mm, and the closing plate 6 is made of steel with an ultimate tensile strength above 950MPa and with a thickness between 0.5mm and 0.9mm, for example 0.7mm. Thus, the RAM 1 is integrated with the rest of the automobile vehicle by securing it to the vehicle body, for example by screwing it to the crash boxes.

Claims

Claims 1- Ram (1) for a bumper beam for a motor vehicle comprising: - an outer beam (2) extending in the transverse direction with a main beam portion (3) comprising an upper beam wall (12), a lower beam wall (14) and a front beam wall (16) connecting the upper beam wall (12) and the lower beam wall (14), said upper beam wall (12), lower beam wall (14) and front beam wall (16), together defining an inner beam volume (17) opening in a rearward direction opposite to the front beam wall (16), - a reinforcement element (4) defining a reinforced region (24) of the outer beam (2), which is inside a portion of the inner volume of said beam (17) and has a cross-sectional area, and defining an inner reinforced volume (25) opening in a rearward direction, - a plate A closure (6) that closes at least part of the internal volume of the beam (17), wherein the cross-sectional area of ​​the reinforcing element (4) has a shape that does not correspond to the shape of the outer beam (2) in the reinforced area (24), characterized in that the reinforcing element comprises at least one upper reinforcing wall (26) connected toThe primary middle reinforcement wall (28) is provided with an upper connecting wall (30), said primary middle reinforcement wall (28) is connected to a secondary middle reinforcement wall (32) by a central connecting wall (34), and said secondary middle reinforcement wall (32) is connected to a lower reinforcing wall (36) by a lower connecting wall (38), said upper and lower connecting walls (30) and (38) are positioned against the front beam wall (16) of the outer beam (2), and said central connecting wall (34) is positioned against the open face of the outer beam (2). 2- Ram (1) according to claim 1, wherein the closing plate (6) completely closes the reinforced internal volume (25).

3. A frame (1) according to claim 1 or 2, wherein the width of the reinforced region (24) along the transverse direction is between 30% and 80% of the width of the main beam portion (3) of the outer beam (2) along said transverse direction. 4- Frame (1) according to any one of claims 1 to 3, wherein the width of the closing plate (6) along the transverse direction is between 50% and 100% of the width of the main beam (3) portion of the outer beam (2) in said transverse direction.

5. A frame (1) according to any one of claims 1 to 4, wherein at least the central connecting wall (34) is located adjacent to the closing plate (6). 6- The ram (1) according to claim 5, wherein said central connecting wall (34) and the closing plate (6) are connected to each other.

7. A frame (1) according to any one of claims 1 to 6, wherein the closing plate (6) comprises at least one opening (44) within the reinforced region (24) and does not comprise any openings within said reinforced region (24).

8. A frame (1) according to any one of claims 1 to 7, wherein the outer beam (2) is a hot-pressed formed steel sheet.

9. A frame (1) according to any one of claims 1 to 8, wherein the outer beam (2) is a hot-pressed, welded steel plate comprising a central beam portion (8) and two side beam portions (10) extending in each direction of said central beam portion (8) in the transverse direction, the width of the central beam portion (8) in the transverse direction being equal to or greater than the width of the reinforced region (24) in the transverse direction. 10- Ram (1) according to claim 9, wherein the central beam portion (8) has a higher failure ductility than the side beam portions (10).

11. Ram (1) according to claim 10, wherein the central beam portion (8) has a failure ductility of at least 0.6 and a maximum bending angle of at least 75°.

12. Ram (1) according to any one of claims 1 to 11, wherein the outer beam (2) has an ultimate tensile strength of at least 950 MPa.

13. Ram (1) according to any one of claims 1 to 12, wherein the reinforcing element (4) has an ultimate tensile strength of at least 500 MPa.

14. Ram (1) according to any one of claims 1 to 13, wherein the closing plate (6) has an ultimate tensile strength of at least 500 MPa.

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