Method for forming ultra-high strength steel sheet and vehicle body covering member manufactured using the same

Abstract

This invention discloses a method for forming ultra-high-strength steel sheets and a vehicle body panel made using this method. The method includes steel sheet cutting, steel sheet bending, and steel sheet welding. Steel sheet cutting includes cutting specific shaped slits into the ultra-high-strength steel sheet. Steel sheet bending includes bending the cut ultra-high-strength steel sheet and stamping at the slits to form raised reinforcing ribs. Steel sheet welding includes welding the slits of the reinforcing ribs. This invention solves the problem of complex processing caused by the high rigidity and difficulty in forming ultra-high-strength steel sheets. It achieves complex shapes through a simple process, effectively controlling problems such as large-area deformation, water accumulation, and corrosion, thus improving the reliability of protective vehicles. This invention provides an efficient, economical, and reliable solution for the application of ultra-high-strength steel sheets in vehicle body panels through a combination of structural innovation and process optimization.

Description

Technical Field

[0001] This invention relates to the field of vehicle body structure design and manufacturing technology, specifically to a method for forming ultra-high strength steel plates and a vehicle body panel made using this method. Background Technology

[0002] In the field of protective vehicle body structure design, ultra-high strength steel plates with a thickness of more than 2mm are often used as outer coverings to meet the requirements of ballistic performance and rigidity.

[0003] However, due to their poor flatness, such materials are prone to uneven deformation when covering large areas, leading to defects in the vehicle's appearance. They can also create water accumulation areas in areas such as the roof, exacerbating the risk of leaks and corrosion. Traditional stamping processes have significant limitations when processing ultra-high-strength steel sheets: the high strength of the material makes forming difficult, the process complex and costly, hindering industrial application.

[0004] Existing technologies cannot simultaneously achieve the forming accuracy, structural performance, and manufacturing cost of ultra-high strength steel plates. There is an urgent need to develop a new forming method to solve the problems of deformation control and industrial production of protective automotive exterior panels. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a method for forming ultra-high strength steel plates that can balance the forming accuracy, structural performance, and manufacturing cost of ultra-high strength steel plates, as well as a vehicle body panel made using this method.

[0006] To achieve this objective, the ultra-high strength steel plate forming method designed in this invention includes steel plate cutting, steel plate bending, and steel plate repair welding;

[0007] The steel plate cutting includes cutting a specific shape of kerf into an ultra-high strength steel plate;

[0008] The steel plate bending includes bending the cut ultra-high strength steel plate and punching at the cut seam to form raised reinforcing ribs at the cut seam.

[0009] The steel plate repair welding includes repairing the cut seams of the reinforcing ribs.

[0010] Furthermore, the method of cutting the steel plate includes cutting one or more cuts of the specific shape on the ultra-high strength steel plate using a laser or water jet.

[0011] Furthermore, the cut slit of the specific shape includes a long cut slit and short cut slits symmetrically arranged at both ends of the long cut slit and perpendicularly intersecting the long cut slit.

[0012] Furthermore, the weld width of both the long and short cutting seams is no greater than 1 mm.

[0013] Furthermore, the weld width of the cut seam of the reinforcing rib is no greater than 4mm.

[0014] Furthermore, the height 'a' of the reinforcing rib and the width 'b' of the reinforcing rib have the following corresponding relationship: a ≤ .

[0015] Furthermore, the ultra-high strength steel plate forming method also includes steel plate welding, wherein the steel plate welding includes beveling, welding, heating and cooling;

[0016] The beveling includes: making a V-shaped 60° bevel on an ultra-high strength steel plate with a thickness of 2-6mm, with a blunt edge of 0.5mm, a pairing gap of 1.5mm, and a misalignment of ≤0.3mm;

[0017] The welding process includes: preheating treatment before welding at a temperature of 100℃, with a preheating range of 50mm around the weld; controlling the interpass temperature within 100℃; using ER70S-G welding wire for the root pass, with a welding current of 90A, a welding voltage of 19V, and a welding speed of 18cm / min; and using ER70S-G welding wire for the fill pass, with a welding current of 160A, a welding voltage of 23V, and a welding speed of 25cm / min.

[0018] The heating and cooling process includes: heating the welded part to 150±5℃, holding it at that temperature for 1 hour, and then air cooling.

[0019] Furthermore, a vehicle body panel made using the aforementioned ultra-high strength steel plate forming method includes a vehicle body, wherein multiple reinforcing ribs are provided on the roof and rear side panels of the vehicle body.

[0020] Furthermore, the reinforcing ribs include multiple roof reinforcing ribs arranged on the roof, spaced apart and parallel to each other along the width of the vehicle body, with each roof reinforcing rib extending along the length of the vehicle body.

[0021] Furthermore, the reinforcing ribs include multiple rear side wall reinforcing ribs arranged in parallel and spaced apart along the width direction of the vehicle body, and the rear side wall reinforcing ribs are arranged along the height direction of the vehicle body.

[0022] The beneficial effects of this invention are: by cutting long and short slits of specific shapes into ultra-high strength steel plates, and forming raised reinforcing ribs during the bending process. The height 'a' and width 'b' of the reinforcing ribs satisfy the relationship a ≤ This process significantly improves the bending stiffness and deformation resistance of the steel plate without compromising material strength. Laser or waterjet cutting (cut width ≤ 1mm) and cold bending processes eliminate the need for complex stamping dies, reducing equipment investment and process complexity, making it suitable for industrial production. Differentiated bevels (V-type / X-type) and welding parameters (such as preheating temperature 100℃~150℃, heat input control) are designed for steel plates of varying thicknesses to ensure weld strength matches the base material, reducing the risk of heat-affected zone cracking. Post-weld heat treatment (180℃~200℃, holding for 3~4 hours) eliminates residual stress and improves overall structural stability. Strictly controlled bending angles and optimized reinforcing rib structure using the tilt effect ensure a smooth appearance while enhancing the steel plate's deflection ability against bullet impacts, thus improving ballistic performance. Weld widths ≤ 4mm (reinforcing rib repair welding) and ≤ 1mm (cut seam) reduce welding defects. Using ER70S-G and ER120S-G welding wires ensures that the weld strength is ≥90% of the base material, meeting the safety requirements of protective vehicles. This invention is applicable to the processing and forming of ultra-high-strength steel plates (such as bulletproof steel and high-strength alloys) with a thickness of 2mm or more, and can be flexibly applied to large flat areas such as roofs and side panels, solving the problem of traditional processes being unable to form them. The pre-forming of reinforcing ribs reduces the need for subsequent sheet metal repair and anti-corrosion treatment, reducing environmental pollution. The optimized structural design and welding process significantly improve the fatigue resistance of body panels and extend the vehicle's service life.

[0023] Taking the body panels of a protective vehicle as an example, the roof reinforcement ribs are arranged parallel to the length of the vehicle body, effectively resisting dents and deformations of the roof caused by external forces or its own weight. The rear side panel reinforcement ribs are arranged along the height of the vehicle body, enhancing the side panel's protection against side collisions. The three-dimensional structure of the reinforcement ribs forms a "grid support," reducing dents and deformations in large flat areas and avoiding the risk of water accumulation and corrosion.

[0024] In summary, this invention solves the complex manufacturing process problems caused by the high rigidity and difficult forming of ultra-high strength steel sheets. It achieves complex shapes through a simplified process, effectively controlling issues such as large-area deformation, water accumulation, and corrosion, thereby improving the reliability of protective vehicles. This invention, through a combination of structural innovation and process optimization, provides an efficient, economical, and reliable solution for the application of ultra-high strength steel sheets in vehicle body panels. Attached Figure Description

[0025] Figure 1 This is a top view of a cut slit of a specific shape being cut into an ultra-high strength steel plate in this invention;

[0026] Figure 2 This is a top view of the process of machining reinforcing ribs on an ultra-high strength steel plate in this invention;

[0027] Figure 3 for Figure 2Sectional view of AA;

[0028] Figure 4 This is a perspective view of the vehicle body in this invention;

[0029] Among them, 1—ultra-high strength steel plate, 2—long cutting seam, 3—short cutting seam, 4—reinforcing rib (4.1—roof reinforcing rib, 4.2—rear side reinforcing rib), 5—vehicle body, 6—roof, 7—rear side, 8—bending position, 9—reinforcing rib forming punch. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Ultra-high strength steel (UHSS) is a type of steel with excellent mechanical properties. Its yield strength is usually above 550 MPa, and its tensile strength can exceed 700 MPa, far exceeding that of ordinary steel. This type of steel mainly relies on the optimization of alloy composition and advanced heat treatment processes to achieve high strength characteristics, while also taking into account plasticity and toughness to a certain extent.

[0031] Main types and characteristics of ultra-high strength steel plates:

[0032] 1. Low-alloy ultra-high strength steel: Composition: Carbon-based with added alloying elements such as chromium, nickel, and molybdenum. Characteristics: Yield strength between 550-1500 MPa, good weldability, suitable for manufacturing aircraft landing gear, rocket engine casings, etc.

[0033] 2. Dual-phase steel (DP steel): Composition: Mainly composed of ferrite and martensite. Characteristics: Yield strength ranges from 350-1000MPa, with high elongation, making it very suitable for automotive body structural components, achieving a balance between lightweight and high safety.

[0034] 3. Martensitic steel (MS steel): Composition: After quenching, it forms a single martensitic structure. Characteristics: Yield strength can reach over 1500MPa, but its plasticity is relatively low. It is often used to manufacture car bumpers, bulletproof armor, etc.

[0035] 4. Hot-formed steel: Composition: A typical example is 22MnB5 steel. Characteristics: After high-temperature austenitization and rapid cooling and quenching, the yield strength can exceed 1000MPa. It is mainly used in key safety components such as automotive A / B pillars and door anti-collision beams.

[0036] Application areas of ultra-high strength steel plates:

[0037] Automotive Industry: Ultra-high strength steel sheets are widely used in automobile manufacturing, including in body frames, chassis components, and airbag supports. They reduce vehicle weight, thus lowering fuel consumption, while also improving collision safety.

[0038] In the aerospace field, it is mainly used in aircraft structural components, landing gear, engine parts, etc., which helps to reduce weight and improve flight efficiency while ensuring strength.

[0039] Military applications: It can be used to manufacture bulletproof vehicles, armor plates, artillery barrels, etc., and can withstand high impact forces.

[0040] In the construction machinery industry, equipment such as excavator buckets and crane booms also use ultra-high strength steel plates to cope with heavy-duty working conditions.

[0041] Currently, the development trend of ultra-high strength steel sheets mainly focuses on further improving strength and formability, such as third-generation automotive steels (QP steel, TWIP steel, etc.). In addition, there is an emphasis on adopting environmentally friendly processes, such as chromium-free passivation treatment, to reduce environmental pollution.

[0042] like Figure 1 As shown in Figure 3, in some embodiments, the ultra-high strength steel plate forming method designed by the present invention is mainly for dual-phase steel (DP steel), martensitic steel (MS steel) and hot-formed steel, and the steps include steel plate cutting, steel plate bending, steel plate repair welding and steel plate welding.

[0043] Example 1

[0044] Example of steel plate cutting:

[0045] Combination Figure 1 The diagram shown illustrates the cutting of ultra-high strength steel plates. The specific operating steps are as follows:

[0046] 1. Material preparation: Select bulletproof ultra-high strength steel plate with a thickness of 8mm (tensile strength ≥1200MPa), and clean the surface to remove oil stains;

[0047] 2. Cutting parameter settings: 8000W fiber laser cutting machine, cutting head and steel plate distance 0.8mm, cutting air pressure 0.8MPa;

[0048] 3. Cutting seam processing: Cut four long cutting seams (500mm long, 0.8mm wide) along the longitudinal direction of the steel plate, and symmetrically cut four sets of short cutting seams (50mm long, perpendicular to the long seams, 0.6mm wide) at both ends of the long cutting seams.

[0049] 4. Quality inspection: Use an electron microscope to inspect the width of the cut (≤1mm) to ensure that there is no slag residue.

[0050] Example 2

[0051] Steel plate bending and forming process:

[0052] Reference Figure 2 —3. Schematic diagram of reinforcing rib forming, specific operations include:

[0053] 1. Mold installation: Install the special reinforcing rib forming punch 9 (tilt angle 45°, R-angle radius 3mm) on the hydraulic bending machine.

[0054] 2. Positioning and pressing:

[0055] Position the cut steel plate on the die, align the cut slit with the center line of the punch, apply 300T pressure for cold stamping, and hold the pressure for 15 seconds.

[0056] 3. Forming of reinforcing ribs:

[0057] Form a continuous stiffener with a height of a = 8 mm (corresponding to a width of b = 50 mm, satisfying a ≤ (with a constraint of approximately 9.8 mm), the surface roughness of the bending area is controlled to be below Ra3.2 μm.

[0058] Example 3

[0059] Combination Figure 2 For reinforced cross-section structures, a welding repair process is implemented:

[0060] 1. Pre-welding treatment: Use an angle grinder to clean the root of the reinforcing rib to form a 30° bevel, and wipe with acetone to remove the oxide layer;

[0061] 2. Welding operation: MAG welding (shielding gas ratio Ar 80% + CO2 20%), welding current 150A, voltage 22V, welding wire diameter 1.2mm (ER120S-G), multi-layer multi-pass welding, single-pass weld width ≤3.5mm;

[0062] 3. Post-weld treatment: Knock the weld to relieve stress, and perform penetrant testing to confirm the absence of cracks.

[0063] Example 4

[0064] Thick plate welding process (taking 6mm thickness as an example), refer to Figure 3 Schematic diagram of welded structure:

[0065] 1. Beveling: Use a V-shaped 60° bevel (0.5mm blunt edge), 1.5mm assembly gap, and ≤0.3mm misalignment;

[0066] 2. Preheating treatment: Electromagnetic induction heating to 100℃, preheating range 50mm, infrared thermometer to monitor temperature in real time;

[0067] 3. Welding implementation: Root pass: ER70S-G welding wire, current 90A, voltage 19V, welding speed 18cm / min; Fill pass: ER70S-G welding wire, current 160A, voltage 23V, welding speed 25cm / min, interpass temperature controlled within 100℃.

[0068] 4. Post-heat treatment: Local induction heating to 150℃ (±5℃), hold for 1 hour, and air cool.

[0069] Example 5

[0070] Application of protective vehicle body panels: such as Figure 4 The body panel structure shown is as follows:

[0071] 1. Roof reinforcement layout: 5 parallel reinforcement ribs (spaced 300mm apart), the direction of the ribs is parallel to the roof longitudinal beams, and the ends are 50mm from the edge line;

[0072] 2. Rear side reinforcement design: Three vertically arranged height reinforcement ribs (spaced 400mm apart), with the lower end of the ribs extending 30mm above the wheel arch;

[0073] 3. Comprehensive performance verification: Flatness test: fluctuation ≤1.5mm within a 3m length; bulletproof test: can withstand 7.62mm armor-piercing bullets (distance 30m, incident angle 60°); salt spray test: no red rust produced after 1000 hours.

[0074] In summary, this invention solves the complex manufacturing process problems caused by the high rigidity and difficult forming of ultra-high strength steel sheet 1. It achieves complex shapes through a simplified process, controls large-area deformation, water accumulation and corrosion, and improves the reliability of protective vehicles. This invention, through a combination of structural innovation and process optimization, provides an efficient, economical, and reliable solution for the application of ultra-high strength steel sheet 1 in vehicle body panels.

[0075] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims. The shapes, dimensions, ratios, angles, and figures used to describe aspects of this specification and the claims are merely examples, and therefore, this specification and the claims are not limited to the details shown. In the following description, detailed descriptions of relevant known functions or configurations will be omitted where it is determined that such detailed descriptions would unnecessarily obscure the focus of this specification and the claims. When using the terms "comprising," "having," and "including" as described in this specification, there may also be another part or other parts, and the terms used are generally singular but may also represent plural forms.

[0076] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention should be considered within the protection scope of the present invention.

Claims

1. A method of forming an ultra-high strength steel sheet, characterized by: It includes steel plate cutting, steel plate bending, and steel plate repair welding; The steel plate cutting includes cutting a cut slit of a specific shape on an ultra-high strength steel plate (1); The steel plate bending includes bending the cut ultra-high strength steel plate (1) and punching at the cut seam to form a raised reinforcing rib (4) at the cut seam. The steel plate repair welding includes repair welding the cut seam of the reinforcing rib (4).

2. The ultra-high strength steel sheet forming method according to claim 1, characterized by: The method of cutting the steel plate includes cutting one or more cuts of the specific shape on the ultra-high strength steel plate (1) by laser or water jet.

3. The ultra-high strength steel sheet forming method according to claim 1 or 2, characterized by: The cut slit of the specific shape includes a long cut slit (2) and a short cut slit (3) symmetrically arranged at both ends of the long cut slit (2) and perpendicularly intersecting the long cut slit (2).

4. The ultra-high strength steel plate forming method as described in claim 3, characterized in that: The weld width of both the long cutting seam (2) and the short cutting seam (3) is no greater than 1 mm.

5. The method for forming ultra-high strength steel plates as described in claim 1, characterized in that: The weld width of the cut seam of the reinforcing rib (4) is no more than 4 mm.

6. The method for forming ultra-high strength steel plates as described in claim 1 or 5, characterized in that: The height a of the reinforcing rib (4) and the width b of the reinforcing rib have the following correspondence: a≤ .

7. The method for forming ultra-high strength steel plates as described in claim 1, characterized in that: It also includes steel plate welding, which includes beveling, welding, heating and cooling; The beveling includes: making a V-shaped 60° bevel on an ultra-high strength steel plate (1) with a thickness of 2-6mm, with a blunt edge of 0.5mm, a pairing gap of 1.5mm, and a misalignment of ≤0.3mm; The welding process includes: preheating treatment before welding at a temperature of 100℃, with a preheating range of 50mm around the weld; controlling the interpass temperature within 100℃; using ER70S-G welding wire for the root pass, with a welding current of 90A, a welding voltage of 19V, and a welding speed of 18cm / min; and using ER70S-G welding wire for the fill pass, with a welding current of 160A, a welding voltage of 23V, and a welding speed of 25cm / min. The heating and cooling process includes: heating the welded part to 150±5℃, holding it at that temperature for 1 hour, and then air cooling.

8. A vehicle body panel made using the ultra-high strength steel sheet forming method according to any one of claims 1-7, comprising a vehicle body (5), characterized in that: Multiple reinforcing ribs (4) are provided on the roof (6) and rear sidewall (7) of the vehicle body (5).

9. The vehicle body panel as described in claim 8, characterized in that: The reinforcing rib (4) includes multiple roof reinforcing ribs (4.1) arranged on the roof (6) and spaced apart and parallel along the width direction of the vehicle body, with each roof reinforcing rib (4.1) extending along the length direction of the vehicle body.

10. The vehicle body panel as described in claim 8 or 9, characterized in that: The reinforcing rib (4) includes multiple rear side wall reinforcing ribs (4.2) arranged on the rear side wall (7) and spaced apart and parallel along the vehicle width direction. The rear side wall reinforcing ribs (4.2) are arranged along the vehicle height direction.

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