REINFORCING STRUCTURAL COMPONENTS

Abstract

A method for manufacturing reinforced steel structural components is described. The method comprises providing a steel blank, selecting one or more reinforcement zones of the steel blank, locally depositing a material on the reinforcement zone to create a local reinforcement on a first side of the steel blank. Locally depositing a material on the reinforcement zone comprises supplying a reinforcement material to the selected reinforcement zone, and substantially simultaneously applying laser heating to melt the reinforcement material and a portion of the steel blank to mix the melted reinforcement material with the melted portion of the steel blank. The method further comprises forming the steel blank with the locally deposited material to shape the reinforced steel structural component. The disclosure further relates to reinforced components obtained using such methods and tools used in such methods.

Claims

1. A method for manufacturing reinforced steel structural components, the method comprising providing an ultra-high strength steel blank, selecting one or more reinforcement zones of the steel blank, locally depositing a material on the reinforcement zone to create a local reinforcement on a first side of the steel blank, wherein locally depositing a material on the reinforcement zone comprises supplying a reinforcement material to the selected reinforcement zone, and applying laser heating to melt the reinforcement material and a portion of the steel blank to mix the melted reinforcement material with the melted portion of the steel blank, and the method further comprising forming the steel blank with the locally deposited material to shape the reinforced steel structural component, wherein forming is done after heating the steel blank with the locally deposited material to an austenization temperature.

2. The method of claim 1, further comprising stamping the heated steel blank with the locally deposited material.

3. The method of claim 2, wherein the method further comprises quenching the heated steel blank with the locally deposited material.

4. The method of claim 1, wherein supplying a reinforcement material to the selected reinforcement zone and applying laser heating to melt the reinforcement material and a portion of the steel blank is done simultaneously.

5. The method of claim 1, wherein locally depositing a material on the reinforcement zone further comprises drawing specific geometric shapes on the first side of the steel blank with the reinforcement material and the laser heating.

6. The method of claim 1, wherein supplying the reinforcement material comprises supplying a metal powder in a gas powder flow.

7. The method of claim 1, wherein supplying the reinforcement material comprises supplying a metal wire.

8. The method of claim 1, wherein the reinforcement material comprises stainless steel.

9. The method of claim 1, wherein the ultra-high strength steel blank is made from boron steel.

10. The method of claim 1, wherein the ultra-high strength steel blank comprises a steel substrate and a metal coating layer and the method further comprises guiding and applying an ablating laser beam along the reinforcement zone to ablate a at least a part of the coating layer of the reinforcement zone prior to locally depositing a material on the reinforcement zone.

11. The method of claim 10, wherein applying the ablating laser beam is done simultaneously with locally depositing a material on the reinforcement zone, the ablating laser beam being applied at a distance between 2 mm to 50 mm upstream from the heating laser beam.

12. The method of claim 1, wherein the ultra-high strength steel blank has a thickness in the range between 0.7 mm to 5 mm.

13. The method of claim 1, wherein the locally deposited material has a thickness from 0.2 mm to 10 mm.

14. A manufacturing system for manufacturing reinforced steel structural components, the manufacturing system comprising a reinforcement depositing system and a forming system, wherein the reinforcement depositing system comprises a laser system having a laser beam source for generating a heating laser beam, a reinforcement material depositor; and a controller connected to the laser beam source and the reinforcement material depositor, wherein the controller is configured to select a reinforcement zone, guide the heating laser beam along the reinforcement zone to apply laser heating and instruct the reinforcement material depositor to locally deposit a reinforcement material onto the reinforcement zone such that laser heating melts the reinforcement material and a portion of an ultra-high strength steel blank to mix the melted reinforcement material with the melted portion of the ultra-high strength steel blank, and the forming system comprises a heating system arranged downstream from the reinforcement depositing system, the heating system being configured to heat the blank with the reinforcement material to an austenization temperature, and a pair of mating dies arranged downstream from the heating system, the pair of mating dies comprising one or more working surfaces that in use face the heated reinforced ultra-high strength steel blank, wherein one or more working surfaces comprises inverse geometries corresponding to the applied reinforcement material, wherein the forming system is further provided with a conveyor or transferring devices for transferring the ultra-high strength steel blank from the reinforcement depositing system to the heating system and for transferring the heated reinforced ultra-high strength steel blank from the heating system to the pair of mating dies.

15. The manufacturing system of claim 14, wherein the laser system further comprises an ablating laser source for generating an ablating laser beam, wherein the ablating laser source is also connected to the controller and is guided along the reinforcement zone to direct the ablating laser beam prior to the heating laser beam.

16. A product as obtainable by a method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Non-limiting examples of the present disclosure will be described in the following with reference to the appended drawings, in which:

[0056] FIG. 1 shows an example of manufacturing a reinforced steel blank;

[0057] FIGS. 2a and 2b show other examples of manufacturing a reinforced steel blank;

[0058] FIGS. 3a-3d show examples of different specific reinforcement geometries that may be obtained by methods substantially as hereinbefore described;

[0059] FIG. 4 shows still a further example of manufacturing a reinforced steel blank;

[0060] FIGS. 5a and 5b show examples of reinforced structural components that may be made with methods substantially as hereinbefore described;

[0061] FIG. 6 shows an example of mating dies that may be used with methods substantially as hereinbefore described; and

[0062] FIG. 7 is a flow diagram of a method of manufacturing reinforced steel structural components according to an example.

DETAILED DESCRIPTION OF EXAMPLES

[0063] In these figures the same reference signs have been used to designate matching elements.

[0064] FIG. 1 shows an example of manufacturing a reinforced steel blank. A laser system 25 may comprise a laser source 1 that may generate a laser beam 35 that may be directed to a surface of the blank 7 to melt a portion 71 the blank surface. A material depositor 40 may further be provided to locally deposit a material 45 on the reinforcement zone. The laser beam 35 may heat and fuse the (reinforcement) material 45 with the portion 71 of the blank being melted by the laser beam 35.

[0065] The laser system 25 may be displaced along a first direction 500 relatively to the steel blank 7 so as to apply the laser beam 35 on the blank surface. The first direction 500 may be a direction along a path that may require reinforcement. Therefore, laser heating may take place only in a previously selected reinforcement zone of the steel blank 7 where reinforcement may be required and while substantially at the same time reinforcement material 45 from the material depositor 40 may be locally deposited. This way heat from the laser beam 35 can melt the reinforcement material 45 and a portion 71 of the steel blank so as to mix them defining the reinforcement 6. The material depositor 40 may be moveable in unison with the laser system 25.

[0066] In some examples, as shown in FIG. 1, the material depositor 40 may form part of a single reinforcement applier 50 that may include the material depositor 40 and the laser system 25. Alternatively, the material depositor may be separate from the laser system but synchronised with the laser system so as to be moveable (the laser system and the material depositor) in tandem.

[0067] FIGS. 2a and 2b show examples of reinforcement appliers in which the material depositor may be a gas powder supply. The laser source 1 may have a laser head 3 from which the laser beam (see FIG. 1) exits.

[0068] The example of FIG. 2a shows an alternative in which the gas powder supply may be coaxially arranged with the laser head 3. In this example, the gas powder supply and the laser head may be arranged such that a gas powder flow 2, indicated with an interrupted line with arrow, and the laser beam may be substantially perpendicular to a surface of the blank 7 on which the reinforcement 6 is to be formed. Alternatively, the coaxially arranged laser head with gas powder supply may be arranged at an angle with respect to the blank. The gas powder flow 2 may be fed to the reinforcement zone while the laser beam is being applied.

[0069] The example of FIG. 2b shows another alternative in which the gas powder supply 20 with nozzle 21 may be arranged at an angle with respect to the blank 7. In this example, the gas powder supply 20 with nozzle 21 may also be arranged at an angle with respect to the laser head 3 thus the gas powder flow 2 is fed at an angle with respect to the laser beam.

[0070] In some examples, argon may be used as a transportation gas, depending on the specific implementation. Other examples of transportation gas may also be foreseen, e.g. nitrogen or helium.

[0071] The examples of FIGS. 2a and 2b further shown a shield gas channel 4 that may also be coaxially provided with respect to the laser head 3 to supply a shield gas flow 5 around the zone on which the reinforcement 6 is to be formed.

[0072] In some examples, helium or a helium based gas may be used as a shielding gas. Alternatively an argon based gas may be used. The flow rate of the shielding gas may e.g. be varied from 1 litre/min to 15 litres/min. In further examples, no shielding gas may be required.

[0073] Alternatively, a solid wire may be used to provide the reinforcement material.

[0074] The laser may have a power sufficient to melt at least an outer surface (or only an outer surface) of the component and thoroughly mix/join the powder throughout the entire zone on which the reinforcement 6 is to be formed.

[0075] In some examples, heating may comprise using a laser having a power of between 2 kW and 16 kW, optionally between 2 and 10 kW. The power of the laser should be enough to melt at least an outer surface of a blank having a typical thickness i.e. in the range of 0.7-5 mm. By increasing the power of the laser the overall velocity of the process may be increased.

[0076] Optionally, a Nd-YAG (Neodymium-doped yttrium aluminum garnet) laser may be used. These lasers are commercially available, and constitute a proven technology. This type of laser may also have sufficient power to melt an outer surface of a blank and allows varying the width of the focal point of the laser and thus of the reinforcement zone. Reducing the size of the spot increases the energy density, whereas increasing the size of the spot enables speeding up the heating process. The laser spot may be very effectively controlled and various types of heating are possible with this type of laser.

[0077] In alternative examples, a CO.sub.2 laser with sufficient power or a diode laser may be used. In further examples, twin spot laser may also be used.

[0078] FIGS. 3a-3d show different examples of specific reinforcement geometries that may be obtained with methods substantially as hereinbefore described. As mentioned above, using a laser to melt a reinforcement material (powder or solid wire) may allow the formation of almost any desired geometry having e.g. different curvature, different size (length, width and height) or even lines crossing each other to define a grid. These methods are quite versatile. No extra material in a zone that does not need reinforcement is provided, and the final weight of a component made from blanks being reinforced substantially as hereinbefore described may thus be optimized.

[0079] For example, FIGS. 3a and 3c show different discrete known shapes such as rectangles, squares, annular rings, half a ring and a cross among other possibilities. FIG. 3b shows curved lines defining each a substantially sinusoidal form and FIG. 3d shows straight lines crossing each other to define a grid.

[0080] It has been found that local reinforcements having a minimum thickness of 0.2 mm lead to good results while optimizing the weight of a final reinforced component made from blanks being reinforced substantially as hereinbefore described. The minimum thickness may be obtained with e.g. only one material (e.g. powder or wire) deposition. Furthermore, each laser exposure and material deposition may involve a maximum thickness of approximate 1 mm. In some examples, the local reinforcement may have a thickness between approximately 0.2 mm and approximately 6 mm. This may be achieved with repetitive depositions of material or by slowing down the process. And in more examples, the local reinforcement may have a thickness between approximately 0.2 mm and approximately 2 mm. In all these examples, the width of the local reinforcement with each material deposition and laser exposure may generally be between approximately 1 mm to approximately 10 mm.

[0081] FIG. 4 shows another example of manufacturing a reinforced steel blank. The example of FIG. 4 differs from that of FIGS. 1, 2a and 2b in that the laser system 25 may further comprise an ablating laser source 27. These examples may particularly be used when reinforcing steel blanks 7 comprising a steel substrate 72 and a metal coating layer 73. As explained above, examples of metal coating layers may comprise aluminum or an aluminum alloy or zinc or a zinc alloy.

[0082] The ablating laser source 27 may generate an ablating laser beam 30. The ablating laser source 27 may be arranged such that the ablating laser beam 30 may be used to ablate a portion of the coating layer 73 prior to locally depositing the reinforcement material 45 e.g. as explained in connection with FIG. 1. The ablating laser beam 30 may be guided by the ablating laser source 27 that may be an individual laser head or may form part of a laser head or system 25 that may be shared between the ablating laser source 27 and the laser source 1. The ablating laser source 27 may be a pulsed laser, e.g. a Q-switched laser having a nominal energy of 450 W delivering a 70 nsec pulse with pulsed energy of 42 mJ.

[0083] In these examples, the laser system 25 may also be relatively displaced in a first direction 500 with respect to the steel blank 7 so as to apply the ablating laser beam 30 on the coating layer 73 of the blank prior to locally depositing the reinforcement material 45. The ablation may therefore take place only in a selected reinforcement zone of the steel blank 7 where reinforcement may be required. The reinforcement material 45 may thus be heated and melted in an ablated reinforcement zone. As used herein, term ablation is used to denote the at least partial elimination of a coating layer.

[0084] As the reinforcement operation progresses along the first direction the reinforcement material that has been heated and melted in the ablated reinforcement zone may begin to cool down and solidify on the ablated reinforcement zone. The solidified reinforcement material may thus cover the whole area that was ablated thus minimising corrosion zones in unprotected border areas.

[0085] The power of the ablating laser source should be enough to melt at least the coating layer of the steel blank.

[0086] The power of the ablating laser source (for example, 450 W) may thus be substantially lower than the power of the laser source (between 2 kW and 16 kW, optionally between 2 kW and 10 kW). By increasing the power of the lasers the overall velocity of the process may be increased.

[0087] Further in the examples of FIG. 4, the laser system 25 may be configured to direct a spot of the laser beam 35 at a distance (downstream) of between approximately 2 mm and approximately 50 mm from the spot of the ablating laser beam 30. In these examples, the distance between the spots of the two laser beams 30 and 35 may depend on various factors. For example, when the metal coating needs to be removed before the material deposition takes place, then the distance may be such that the deposited material may not be accidentally removed as part of the ablated material removal. In other words, any removal of coating from the ablated zone needs to be completed or take place sufficiently far away (before) deposition of reinforcement material takes place in the ablated area. One way to remove the ablated material may be with an air blowing system. However, if no further removal needs to take place (for example because the ablation process pushes the ablated coating off the reinforcement zone) then the distance between the two spots may be relatively close.

[0088] In some examples, the laser source and the ablating laser source may be comprised in a single laser system 25 or head as shown in the example of FIG. 4. This allows for the two laser beams to be precisely aligned during the entire ablation and melting process which, in turn allows for a higher speed of reinforcement.

[0089] In some examples, the laser source may be comprised in a first laser head and the ablating laser source in a second laser head. The first and second laser heads may thus be arranged to be moveable in unison. Using two laser heads allows for separate control of movement characteristics of the spots. For example, the laser head responsible for the ablation spot (or spots in case of twin-spot beam) may displace the spot in a second direction while the laser head responsible for melting the reinforcement material moves in the first direction to e.g. perform sweeping of the ablated area to remove any residues of the ablation. The second head would then only provide movement of the ablating laser beam along the first direction.

[0090] An aspect of applying the ablating laser beam prior to or substantially simultaneously with the laser beam for heating and the material deposition is that the reinforcement may be homogeneously dissolved on and adhere to the ablated area as the ablated area is already preheated from the ablating laser and the two processes (ablation and material deposition) are not separated in time and space but are performed successively before the ablated area is allowed to cool down. The reinforcement may thus adhere and dilute directly with the steel substrate in the ablating coating layer zone leaving substantially no ablated steel substrate uncovered.

[0091] FIGS. 5a and 5b show different reinforced components obtained by any method substantially as herein described. In the example of FIG. 5a a bar 9 e.g. a cross/side member is schematically illustrated. In the example of FIG. 5b a B pillar 8 is schematically illustrated. Both components 8 and 9 may be formed e.g. by a HFDQ process of a blank reinforced by any of the methods substantially as hereinbefore described. In alternative examples, other ways of forming the component may also be foreseen such as cold forming, hydroforming or roll forming. Reinforcements 80 and 90 may be added on the blank prior to forming, either with a prior ablating step as explained in connection with FIG. 4, i.e. by ablating the coating layer and depositing a reinforcement material while applying the laser beam to melt the reinforcement material or as explained in connection with FIGS. 1-2b, i.e. by applying the laser beam substantially simultaneously with the reinforcement material on a blank surface.

[0092] The reinforcements 80 and 90 are designed e.g. to direct tensions and increase stiffness (rigidity) of the final component that will be made with such a reinforced blank. The reinforcements may be applied e.g. in order to improve strength in case of an impact in areas such as corners, end portions and e.g. in order to add strength to the component due to e.g. a hole made during manufacture so that the whole strength of the final component that is made with such a reinforced blank is not affected by the presence of the hole. In general in a component, reinforcements may be required in those areas that need to withstand most loads, e.g. in a B pillar these areas are the corners.

[0093] FIG. 6 shows a press tool configured to form a reinforced blank by any of the methods substantially as hereinbefore described, e.g. by a HFDQ process or a cold forming process.

[0094] The press tool may comprise upper 61 and lower 62 mating dies and a mechanism (not shown) configured to provide upwards and downwards press progression (see arrows) of the upper die 61 with respect to the lower die 62. A press progression mechanism may be driven mechanically, hydraulically of servo-mechanically. The upper die 61 and the lower die 62 may respectively comprise an upper working surface 611 and a lower working surface 621 that in use face the reinforced blank 100 to be formed or hot formed.

[0095] In the example of FIG. 6, the upper working surface 611 may comprise a pair of slots or recesses 612 defining an inverse geometry of a reinforcement 101 of a blank reinforced by any of the methods substantially as hereinbefore described. In further examples, other number of slots or recesses may be provided depending on the reinforcements applied to the reinforced blanks.

[0096] Alternatively, both working surfaces (upper and lower) may comprise slots or recesses matching a reinforced material that may be applied at both sides of a blank by any of the methods substantially as hereinbefore described.

[0097] Depending if a cold forming or a hot forming process is to be performed by the press tool, the upper and lower mating dies may comprise e.g. channels with cold fluid e.g. water and/or cold air passing through the channels provided in the dies. In the water channels, the speed of circulation of the water at the channels may be high, thus the water evaporation may be avoided. The channels with cold fluid allow cooling down of the reinforced blank being formed at a rate such that a final reinforced formed component results in a martensite microstructure.

[0098] A control system may further be provided, thus the temperature of the dies may be controlled. In further examples, other ways of adapting the dies to operate at lower or higher temperatures may also be foreseen, e.g. in circumstances, heating systems may be provided to control the cooling rate and/or to create areas having a ferrite-pearlite microstructure, i.e. soft zones which are zones in the component having reduced mechanical strength as compared to other parts of the component. Temperature sensors and control systems may also be provided to control the temperature of the dies and/or in transferring systems that may be used for conveying the blanks from e.g. the oven to the press tool.

[0099] Automatic transfer devices, e.g. a plurality of industrial robots, or a conveyor may also be provided to transfer of blanks e.g. from the oven to the press tool. In more examples, one or more centering elements, e.g. pins and/or guiding devices, may also be provided to aid centering the reinforced blanks in the dies working surfaces.

[0100] FIG. 7 is a flow diagram of a method of manufacturing reinforced steel blank according to an example. At a first block 701, a steel blank is provided. In some examples, the steel blank may have a coating layer of aluminum or of an aluminum alloy. Alternatively other metal coating layers may be foreseen e.g. including a zinc or zinc alloy coating layer. In more alternatives, no metal coating layer may be present in the steel blank.

[0101] In all cases, at block 702, a reinforcement zone of the steel blank may be selected. At block 703, a first direction in the reinforcement zone may be selected. Then, when blanks comprising a metal coating layer are being used, at block 704, an ablating laser beam may be guided along the first direction to ablate at least a part of the metal coating layer of the reinforcement zone.

[0102] In all cases, at block 705, a material may be locally deposited on the reinforcement zone (which may be or have been ablated or not) to create a local reinforcement on a first side of the blank. At block 706, laser heating may be substantially simultaneously applied with the material deposition, along the first direction to melt the reinforcement material (metal filler) and create the reinforcement. At block 707, the reinforced blank may be formed to obtain the reinforced structural component. In circumstances a further intermediate step may include actively cooling or allowing to cool in ambient air the reinforced blank prior to the forming process to let the reinforcement material adhere to the (ablated or not) steel surface of the blank.

[0103] Although only a number of examples have been disclosed herein, other alternatives, modifications, uses and/or equivalents thereof are possible. Furthermore, all possible combinations of the described examples are also covered. Thus, the scope of the present disclosure should not be limited by particular examples, but should be determined only by a fair reading of the claims that follow.