Method for producing a structural part inside an automobile including a locally reinforced area

Abstract

A method for producing a structural part inside an automobile including a localized reinforced area. The method includes the following steps: - forming an inner upper front base plate (20), an inner central base plate (24) and an inner side rail plate. - hot pressing the inner upper front base plate (20). - hot pressing the inner central base plate (24). - hot pressing the inner side rail plate. - before the hot pressing steps, the method includes the following steps: - connecting the inner upper front base reinforcement plate (22) to the inner upper front base plate (20), said inner upper front base reinforcement plate (22), with the base plate. The inner upper front (20) of the press is heated,\n-attaching the inner central base reinforcement sheet (26) to the inner central base sheet piece (24), said inner central base reinforcement sheet (26), to the inner central base sheet (24) of the press is heated.

Description

Method for producing a structural part in an automobile including a localized reinforced area This invention relates to a method for producing a structural component in an automobile of the type comprising an inner upper front pillar, an inner center pillar, and an inner side rail extending between the inner upper front pillar and the upper end of the inner center pillar, said method comprising the following steps: -Create the inner upper front base plate, inner central base plate, and inner side rail plate, -Hot press of the inner upper front base plate to shape the inner upper front base, -Hot pressing of the inner central base sheet to shape the inner central base, -Hot press of the inner side rail sheet to form the inner side rail, -Assembling the inner upper front pillar and the inner center pillar to the inner side rail to obtain the inner structural part of the car. The invention also relates to a method for producing an automobile structural part with such an automobile interior structural part. Such a structural part inside the car, which forms the upper door ring part of the motor vehicle, must have certain mechanical characteristics in order to be able to protect the passengers of the motor vehicle against any kind of penetration into the passenger compartment. The upper door ring piece is specifically placed to prevent the vehicle's roof from penetrating the passenger compartment, or breaking off the roof, in the event of a vehicle rollover. For this purpose, it is common to reinforce the central pillar and the upper front pillar with reinforcing elements to prevent these pillars from bending in the event of an overturn, which would cause the roof to break. The reinforcing elements are attached, for example, to the central pillar sections and to the upper front pillar in the form of patches that have a complementary shape to the central pillar section and the upper front pillar to which the reinforcing elements are attached. The reinforcing element must therefore be shaped, for example during a cold pressing step, and then connected to the complementary area of ​​the base that is to be reinforced. However, the small dimensions of the reinforcing element make it difficult to handle during the pressing step and during the connecting step. Therefore, the production of the reinforced structural part is not optimized. Another solution is to prepare a reinforced sheet, which has a localized thicker area in the area to be reinforced, and then shape the sheet into a base. However, this solution is also not satisfactory in that different sheets must be provided for each model of automobile vehicle depending on the location of the reinforced area and depending on the requirements of said model, for example in terms of the dimensions of the reinforced area. One of the objectives of this invention is to overcome these problems by proposing a method for producing a reinforced structural component that can be implemented in a simple manner and can be easily adapted to several vehicle models. To this end, the invention relates to a method of the type mentioned above, in which the method comprises, prior to the post-heating steps, the following steps: - connecting the inner upper front leg reinforcement sheet to the local part of the inner upper front leg sheet, the inner upper front leg reinforcement sheet is hot pressed to the inner upper front leg sheet such that the inner upper front leg includes a local reinforced area having an increased thickness relative to the outside of said local reinforced area of ​​the inner upper front leg, -Connecting the inner central support reinforcement sheet to the local part of the inner central support sheet, said inner central support reinforcement sheet is pressed into the inner central support sheet in a perm manner such that the inner central support includes a local reinforced area having an increased thickness relative to the outside of said local reinforced area of ​​the inner central support. Attaching the reinforcement sheet to the base piece before the hot pressing step avoids the manipulation of a small part during the hot pressing step because the reinforcement sheets are not hot pressed with the base sheets, which makes it easier to work with. In addition, the reinforcement specifications can be easily modified by modifying the reinforcement sheet specifications without modifying the base sheets, and the same base sheets can be used for different automobile vehicle models with different reinforcement requirements. According to other advantageous aspects of the present invention, the undercarriage of the vehicle comprises one or more of the following features, taken alone or in any technically possible combination: -The inner upper front support plate and the inner side rail plate are made of a single piece, said inner upper front support plate and the inner side rail plate are hot pressed in a single step with the inner upper front support reinforcement plate; -The upper front base reinforcement plate and the inner center base reinforcement plate are connected to the upper front inner base plate and to the inner center base plate by a resistance spot welding step or laser welding; -The inner center post is connected to the inner side rail by a spot welding or laser welding step; -The inner upper front support, inner center support and inner side rail are each made from a hardened steel piece with a tensile strength greater than 1200 MPa; -Composition of hardened steel in weight %: -0.15% ≤ C ≤ 0.5%, 0.5% ≤ Mn ≤ 3%, 0.1% ≤ Si ≤ 1%, 0.005% ≤ Cr ≤ 1%, Ti ≤ 0.2%, Al ≤ 0.1%, S ≤ 0.05%, P ≤ 0.1%, B ≤ 0.010%, residual iron and unavoidable impurities resulting from handling; or -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%, residual iron and unavoidable impurities resulting from handling; or -0.24% ≤ 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%, %, residual iron and unavoidable impurities caused by handling; -The inner upper front base plate, the inner central base plate, the inner upper front base reinforcement plate and the inner central base reinforcement plate have a structure consisting essentially of ferrite and pearlite before said plates are hot pressed, the inner upper front base and the inner central base have a structure consisting of 95% or more of martensite after hot pressing; - the inner upper front base plate and the inner central base plate each have a thickness substantially comprised between 0.7 and 1.5 mm, and the inner upper front base reinforcement plate and the inner central base reinforcement plate each have a thickness substantially comprised between 0.5 and 1.5 mm; -The inner central base reinforcement sheet is connected to the central piece of the inner central base sheet, said central piece being spaced from the upper end of the inner central base sheet; - The inner front pillar reinforcement sheet is connected to the upper end of the inner front pillar sheet; the invention also relates to a method for producing a structural part of an automobile, which includes an upper front pillar, a central pillar and a side rail extending between the upper end and the upper front pillar and the upper end of the central pillar, said method comprising the following steps: -Production of an automotive interior structural part as described above, -Producing an interior structural part of an automobile by connecting the outer upper front pillar and the outer center pillar to the outer side rail, -Connecting an interior structural part of the car to an exterior structural part of the car to form an automobile structural part. According to another feature of the present invention, the outer structural member of the automobile has a concave cross-section, the inner structural member of the automobile is positioned near the cavity of the outer structural member of the automobile. Other aspects and advantages of the invention will become apparent upon reading the following description, which is illustrated by way of example and with reference to the accompanying drawings, in which: - Figure 1 is a front view of an interior structural part of an automobile obtained by the method according to the present invention, -Figure 2 is an exploded perspective view of the interior structural component of Figure 1, and - Figure 3 is a front view of the sheets used in the method according to this invention. This invention relates to a method for producing an interior structural part of an automobile 1, which includes an interior upper front pillar 2, an interior center pillar 4, and an interior side rail 6. Such an interior automobile structural part 1 is a car structural part for forming, with a complementary exterior automobile structural part, an upper part of a door ring to surround and receive the front door of the automobile vehicle. The terms "inside" and "outside" are defined relative to the inside and outside of the motor vehicle. Inside defines that which curves inwardly of the vehicle and outside defines that which curves outwardly of the vehicle. The terms "lower" and "upper" are defined relative to the elevational direction of the motor vehicle under normal conditions of use. As is known, the upper front pillar extends in the height direction of the vehicle and is for connecting to the lower front pillar to form the front pillar of the vehicle, also known as the A-pillar. The central pillar, also known as the B-pillar, extends in the height direction of the vehicle and is for receiving the moving means in the vehicle and for extending between the front door and the rear door in the case of a five-bay vehicle. The central pillar extends substantially the entire height of the passenger compartment. The side rail extends in the rear-front direction of the vehicle, or in the longitudinal direction, between the front longitudinal end 8 and the rear longitudinal end 10. The side rail connects the upper front pillar and the central pillar and is for supporting the roof panel of the vehicle. The inner upper front leg 2 and the inner side rail 6 are for example made of a single piece and the upper end 12 of the inner central leg 4 is connected to the inner side rail 6, for example to the central piece 14 of the inner side rail 6. The central piece 14 extends between the front longitudinal end 8 and the rear longitudinal end 10. According to this example, the inner side rail 6 can extend substantially the entire length of the passenger compartment such that the rear longitudinal end 10 is connected to the rear leg of the vehicle (not shown). Alternatively, the inner central leg 4 can be connected to the rear longitudinal end 10 of the inner side rail 6. The inner upper front support 2, the inner side rail 6 and the inner central support are made of a pressed hardened steel piece having a tensile strength greater than 1200 MPa, for example greater than 1300 MPa. The pressed hardened steel piece exhibits a martensitic structure. Such high mechanical properties make it a suitable piece for forming a reinforcing structure such as a door ring. The composition of such steel may for example include, in wt%: 0.15% ≤ C ≤ 0.5%, 0.5% ≤ Mn ≤ 3%, 0.1% ≤ Si ≤ 1%, 0.005% ≤ Cr ≤ 1%, Ti ≤ 0.2%, Al ≤ 0.1%, S ≤ 0.05%, P ≤ 0.1%, B ≤ 0.010%, residual iron or unavoidable impurities resulting from handling. According to another preferred embodiment, the steel composition comprises, for example, in wt%: 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%, residual iron or unavoidable impurities resulting from handling. With this composition range, the tensile strength of the hardened compact is between 1300 and 1650 MPa. According to another preferred embodiment, the steel composition comprises, for example, in wt%: 0.24% ≤ 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%, %, residual iron or unavoidable impurities resulting from handling. With this composition range, the tensile strength of the hardened compact is greater than 1800 MPa. Steel may be uncoated or coated, for example by any suitable process such as hot dip galvanizing, electroplating, vacuum galvanizing or galvanizing. The inner upper front leg 2 and the inner central leg 4 each include a localized reinforced area 16 and 18. The reinforced areas 16 and 18 provide an increased thickness, which is greater than the thickness of the rest of the legs, namely the thickness of the leg outside the reinforced areas 16 and 18. For example, the inner upper front leg 2 and the inner central leg provide a thickness that is substantially between 0.7 and 1.5 mm outside the reinforced areas 16 and 18 and a thickness that is substantially between 1.2 and 3 mm in the reinforced areas 16 and 18. Local, meaning that the reinforcement zones 16 and 18 do not extend over the entire surface of the inner upper front base 2 and the inner central base 4. The reinforced area 16 of the inner upper front pillar 2 extends at the upper end of the inner upper front pillar 2, i.e. at the junction between the inner upper front pillar 2 and the inner side rail 6. The reinforced area 18 of the inner central pillar 4 extends in the central area of ​​the central pillar, i.e. in the area spaced from the lower end and the upper end 12 of the inner central pillar 4. More specifically, in a vehicle mounted with the door closed, the reinforced areas 16 and 18 extend substantially opposite the window frame at the front of the vehicle, in each direction of said window. Thus, the reinforced areas 16 and 18 extend substantially at the same height in the height direction of the vehicle. Such reinforced areas allow the vehicle door hinges to withstand a rollover without the roof invading the passenger compartment, while allowing the main door hinge piece to have a reduced thickness, which is proportional to the thickness of the base outside the reinforced areas. As a result, the structural part of the automobile can be made lightweight while maintaining satisfactory mechanical properties. The method of producing the interior structural part of the automobile 1 will now be explained. As shown in Figure 3, a sheet 20 is provided to form the inner upper front base 2. According to the example shown in Figure 3, this inner upper front base sheet 20 includes a piece that forms the inner side rail sheet to form the inner side rail 6. In other words, the inner upper front base sheet 20 and the inner side rail sheet are formed from a single sheet. The sheet 20 is substantially flat and is cut, for example, from a steel sheet having a color and dimensions suitable for forming the inner front base and side rail after hot pressing. The steel sheet has a structure consisting essentially of ferrite and pearlite and is arranged so that the inner upper front base and side rail have a structure consisting of 95% or more martensite after hot pressing. The thickness of the sheet is 20 times the thickness of the inner front base 2 and the inner side rail 6 outside the reinforced area 16. The inner upper front support reinforcement plate 22 is also prepared, for example by cutting the plate 22 from a steel sheet of the same material as that used for the inner front support reinforcement plate 20. The inner upper front support reinforcement plate 22 has a color and dimensions compatible to form a reinforced area 16 when assembled and hot-pressed with the inner upper front support plate 20. Thus, the inner upper front support reinforcement plate 22 has a thickness equal to the difference in thickness between the thickness of the reinforced area 16 and the thickness of the inner upper front support plate 20. Thus, the inner upper front support reinforcement plate 22 has a thickness that is essentially comprised between 0.5 and 1.5 mm. The color of the inner upper front leg reinforcement sheet 22 is the same color as the inner upper front leg reinforcement sheet section 20, where the reinforced area 16 is to extend. The inner upper front support reinforcement plate 22 is connected to the inner upper front support plate 20 at the location where the reinforced area 16 is to extend, i.e. at the upper end of the inner upper front support plate 20, as shown in Figure 3. The inner upper front support reinforcement plate 22 is spot welded or laser welded to the inner front support plate 20, for example. The assembled sheet is then heated in a press to obtain the shape of the inner front base 2 and the shape of the inner side rail 6. To form the inner center base 4, an inner center base sheet 24 is provided. The inner center base plate 24 is substantially flat and is cut from, for example, a steel plate to have a suitable color and dimensions to form the inner center base after hot pressing. The steel plate has a structure essentially of ferrite and pearlite which are arranged so that the inner upper front base and the side rail have a structure comprising 95% or more of martensite after hot pressing. The thickness of the sheet 24 is equal to the thickness of the inner central base 4 outside the reinforced area 18. The inner center base reinforcement plate 26 is also prepared, for example by cutting the plate 26 from a steel sheet of the same material as the inner center base reinforcement plate 24. The inner center base reinforcement plate 26 has a color and dimensions compatible to form the reinforced area 18 when assembled and hot-pressed to the inner center base plate 24. As a result, the inner center base reinforcement plate 26 has a thickness equal to the difference in thickness between the thickness of the reinforced area 18 and the thickness of the inner center base plate 20. The inner center base reinforcement plate 24 therefore has a thickness that is essentially comprised between 0.5 and 1.5 mm. The color of the inner center base reinforcement sheet 24 is the same color as the portion of the inner center base reinforcement sheet 24 to which the reinforced area 18 is to extend. The inner center base reinforcement plate 26 is connected to the inner center base plate 24 at the location where the reinforced area 18 is to extend, i.e. at a central portion of the inner center base plate 24, as shown in FIG. 3. The inner center base reinforcement plate 26 is, for example, spot welded or laser welded to the inner center base plate 24. The assembled sheet is then heated in a press to take the shape of the inner central base 4. The inner center post 4 is then connected to the inner side rail 6, for example by resistance spot welding or laser welding, to form the interior structural part of the car as previously described. Attaching the inner front base reinforcement sheet 22 and the inner center base reinforcement sheet 26 to the inner front base sheet 20 and to the inner center base sheet 24, respectively, prior to the hot pressing steps facilitates handling of the sheets during said hot pressing steps. It is worth noting that the materials of the reinforcement plates 22 and 26 can be different from the materials of the base plates 20 and 24, depending on the desired mechanical properties of the reinforced areas 16 and 18. Furthermore, modification of the mechanical characteristics of the reinforced areas 16 and 18 can be easily achieved by changing the reinforcing plates 22 and 26. As a result, the same base plates 20 and 24 can be used for different vehicle models by changing the reinforcing plates 22 and 26 to adapt to the characteristics of the reinforced areas 16 and 18. The obtained automobile interior structural member 1 can then be assembled with an automobile exterior structural member to form an automobile exterior structural member. Such an automobile exterior structural member includes an outer upper front leg, an outer center leg and an outer side rail and can be produced by a method similar to that described above. The outer structural member has, for example, a concave cross-section such as a U-shape that opens toward the interior of the vehicle. The automobile interior structural member 1 is adapted to close the cavity of the automobile exterior structural member. The resulting car structural component is both lightweight and exceptionally strong, specifically designed to prevent the roof from breaking in a rollover.

Claims

ادعاها 1-روشی برای تولید یک قطعه سازه ای داخلی اتومبیل (1) که شامل یک پایه جلویی بالایی داخلی (2)، یک پایه مرکزی داخلی (4) و یک ریل جنبی داخلی (6)که مابین پایه جلویی بالایی داخلی (2) و انتهای بالایی (12)پایه مرکزی داخلی (4)امتداد پیدا می کند است، روش مذکور شامل مراحل زیر است: -تهیه یک ورق پایه جلویی بالایی داخلی (20)، یک ورق پایه مرکزی داخلی (24) و یک ورق ریل جنبی داخلی، -مهرزنی داغ ورق پایه جلویی بالایی داخلی (20)برای تشکیل پایه جلویی بالایی داخلی (2)، - مهرزنی داغ ورق پایه مرکزی داخلی (24) برای تشکیل پایه مرکزی داخلی (4)، - مهرزنی داغ ورق ریل جنبی داخلی برای تشکیل ریل جنبی داخلی (6)، -مونتاژ کردن پایه جلویی بالایی داخلی (2) و پایه مرکزی داخلی (4)به ریل جنبی داخلی (6)برای بدست آوردن قطعه سازه ای داخلی اتومبیل، با این ویژگی که که روش شامل، قبل از مراحل مهرزنی داغ، مراحل زیراست: -متصل کردن ورق تقویت پایه جلویی بالایی داخلی (22) به یک قطعه موضعی ورق پایه جلویی بالایی داخلی (20)، ورق تقویت پایه جلویی بالایی داخلی مذکور (22)، به ورق پایه جلویی بالایی داخلی (20)طوری مهرزنی داغ می شود که پایه جلویی بالایی داخلی (2) شامل یک منطقه تقویت شده موضعی (16)است که دارای ضخامت افزایش یافته نسبت به پایه جلویی بالایی داخلی (2) خارج از منطقه تقویت شده موضعی مذکور (16)است، -متصل کردن ورق تقویت پایه مرکزی داخلی (26)به قطعه موضعی ورق پایه مرکزی داخلی (24)، ورق تقویت پایه مرکزی داخلی مذکور (26) طوری به ورق پایه مرکزی داخلی (24) مهرزنی داغ می شود که پایه مرکزی داخلی (4)شامل یک منطقه تقویت شده موضعی (18)است که دارای ضخامت افزایش یافته نسبت به خارج از منطقه تقویت شده موضعی مذکور پایه مرکزی داخلی (18)است.2-روش مطابق ادعای 1، که در آن ورق پایه جلویی بالایی داخلی (20) و ورق ریل جنبی داخلی از یک قطعه منفرد ساخته می شود، پایه جلویی بالایی داخلی مذکور و ورق ریل جنبی داخلی، به ورق تقویتپایه جلویی بالایی داخلی (22) در یک مرحله منفرد مهرزنی داغ می شود.3-روش مطابق ادعای 1 یا 2، که در آن ورق تقویتپایه جلویی بالایی داخلی (22) و ورق تقویت پایه مرکزی داخلی (26)، به ورق پایه جلویی بالایی داخلی (20) و به ورق پایه مرکزی داخلی (24) بوسیله یک مرحله جوش نقطه ای مقاوم یا جوش لیزری متصل می شوند.4-روش مطابق با هر یک از ادعاهای 1 تا 3، که در آن پایه مرکزی داخلی (4)، به ریل جنبی داخلی (6)بوسیله مرحله جوش لیزری متصل می شود.

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