Ultra-high-strength steel plate forming method and vehicle body covering part manufactured through method

Abstract

The invention discloses an ultrahigh-strength steel plate forming method and a vehicle body covering part manufactured through the method. The ultrahigh-strength steel plate forming method comprises the steps of steel plate cutting, steel plate bending and steel plate repair welding. The steel plate cutting comprises the step of cutting a cutting seam in a specific shape in the ultrahigh-strength steel plate; steel plate bending comprises the steps that the cut ultrahigh-strength steel plate is bent, punching is conducted on a cutting seam, and a protruding reinforcing rib is formed on the cutting seam; and the steel plate repair welding comprises repair welding of cutting seams of the reinforcing ribs. According to the invention, the problem of complex process caused by high rigidity and difficult forming of the ultrahigh-strength steel plate is solved. Complex modeling is achieved through a simple process, the problems of large-plane deformation, accumulated water corrosion and the like are effectively controlled, and the reliability of the protection type automobile is improved. Through combination of structural innovation and process optimization, an efficient, economical and reliable solution is provided for application of the ultrahigh-strength steel plate in the vehicle body covering part.

Description

Technical Field

[0001] The present invention relates to the technical field of body structure design and manufacturing, and specifically refers to a forming method for ultra-high strength steel plates and a body covering part manufactured by using this method. Background Art

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

[0003] However, due to the poor flatness of such materials themselves, when the covering area is large, it is easy to produce concave and convex deformations, resulting in body appearance defects. At the same time, water accumulation areas may be formed in areas such as the roof cover, exacerbating the risks of water leakage and rust. Traditional stamping processes have significant limitations in dealing with ultra-high strength steel plates: the high rigidity and strength of the materials lead to great forming difficulties, complex processes and high costs, making it difficult to achieve industrial application.

[0004] The existing technologies cannot balance 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 outer covering parts. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies of the above background art, and provide a forming method for ultra-high strength steel plates that can balance the forming accuracy, structural performance and manufacturing cost of ultra-high strength steel plates, and a body covering part manufactured by using this method.

[0006] To achieve this purpose, the forming method for ultra-high strength steel plates designed by the present invention includes steel plate cutting, steel plate bending and steel plate repair welding;

[0007] The steel plate cutting includes cutting cutting seams with specific shapes on the ultra-high strength steel plate;

[0008] The steel plate bending includes bending the cut ultra-high strength steel plate and stamping at the cutting seams to form raised reinforcing ribs at the cutting seams;

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

[0010] Further, the method of steel plate cutting includes cutting one or more of the above-mentioned specific-shaped cutting seams on the ultra-high strength steel plate by laser or water jet.

[0011] Further, the specific-shaped cutting seams include long cutting seams and short cutting seams symmetrically arranged at both ends of the long cutting seams and perpendicularly intersecting the long cutting seams.

[0012] Further, the weld widths of the long cutting seams and the short cutting seams are both not greater than 1 mm.

[0013] Further, the weld width of the cutting seam of the reinforcing rib is not greater than 4 mm.

[0014] Further, the following corresponding relationship exists between the convex height a and the convex width b of the reinforcing rib:

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

[0016] The beveling includes: for an ultra-high strength steel plate (1) with a thickness less than 2 - 6 mm, a V-shaped 60° bevel is opened, the root face is 0.5 mm, the fit-up gap is 1.5 mm, and the misalignment is ≤ 0.3 mm;

[0017] The welding includes: preheating treatment is performed before welding, the preheating temperature is 100 °C, and the preheating range is 50 mm around the weld; the interpass temperature is controlled within 100 °C; for the root pass welding, an ER70S-G welding wire is used, the welding current is 90 A, the welding voltage is 19 V, and the welding speed is 18 cm / min. For the filler pass welding, an ER70S-G welding wire is used, the welding current is 160 A, the welding voltage is 23 V, and the welding speed is 25 cm / min;

[0018] The heating and cooling includes: heating the welded part to 150 ± 5 °C, holding for 1 h, and air cooling.

[0019] Furthermore, a body panel manufactured by using the above-mentioned ultra-high strength steel plate forming method includes a vehicle body, and a plurality of the reinforcing ribs are provided on the roof and the rear side panel of the vehicle body.

[0020] Further, the reinforcing rib includes a plurality of roof reinforcing ribs arranged on the roof at intervals and parallel to each other in the vehicle body width direction, and the roof reinforcing ribs are arranged in the vehicle body length direction.

[0021] Still further, the reinforcing rib includes a plurality of rear side panel reinforcing ribs arranged on the rear side panel at intervals and parallel to each other in the vehicle body width direction, and the rear side panel reinforcing ribs are arranged in the vehicle body height direction.

[0022] The beneficial effects of the present invention are: by cutting long cutting seams and short cutting seams with specific shapes on the ultra-high strength steel plate, and forming convex reinforcing ribs during the bending process. The convex height a and width b of the reinforcing rib satisfy the relational expression Ensure that, without reducing the material strength, the flexural stiffness and anti-deformation ability of the steel plate are significantly improved. Laser or waterjet cutting (cutting seam width ≤ 1 mm) and cold bending process are adopted, eliminating the need for complex stamping dies, reducing equipment investment and process difficulty, and being suitable for industrial production. Differentiated grooves (V-shaped / X-shaped) and welding parameters (such as preheating temperature 100°C - 150°C, heat input control) are designed for steel plates of different thicknesses to ensure that the weld strength matches that of the base metal and reduce the risk of cracking in the heat-affected zone. Post-weld heat treatment (holding at 180°C - 200°C for 3 - 4 hours) eliminates residual stress and improves the overall structural stability. The bending angle is strictly controlled, and the reinforcing rib structure is optimized using the inclination effect. While ensuring a flat appearance, it enhances the deflection ability of the steel plate against bullet impact and improves the bulletproof performance. The weld width ≤ 4 mm (reinforcing rib repair welding) and ≤ 1 mm (cutting seam) reduce welding defects. ER70S-G and ER120S-G welding wires are used to ensure that the weld strength ≥ 90% of the base metal, meeting the safety requirements of armored vehicles. The present invention is applicable to the processing and forming of ultra-high strength steel plates (such as bulletproof steel, high-strength alloys) with a thickness of more than 2 mm, and can be flexibly applied to large flat areas such as the roof and side panels, solving the problem that traditional processes cannot be formed. The pre-forming of the reinforcing ribs reduces the need for subsequent sheet metal repair and anti-corrosion treatment and reduces environmental pollution. The optimized structural design and welding process significantly improve the fatigue resistance of the body panels and extend the service life of the vehicle.

[0023] Taking the body panels of armored vehicles as an example, the roof reinforcing ribs are arranged parallel to the vehicle body length direction, effectively resisting the concave deformation of the roof caused by external forces or its own weight. The rear side panel reinforcing ribs are arranged along the vehicle body height direction, enhancing the protection ability of the side panel against side collisions. The three-dimensional structure of the reinforcing ribs forms a "grid support", reducing the concave and convex deformation of large flat areas and avoiding the risks of water accumulation and corrosion.

[0024] In summary, the present invention solves the problem of complex processes caused by the high stiffness and difficult forming of ultra-high strength steel plates. It realizes complex shapes through simple processes, effectively controls problems such as large flat area deformation, water accumulation and corrosion, and improves the reliability of armored vehicles. Through the combination of structural innovation and process optimization, the present invention provides an efficient, economical and reliable solution for the application of ultra-high strength steel plates in body panels. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the top view of cutting a specific-shaped cutting seam on the ultra-high strength steel plate in the present invention;

[0026] Figure 2 It is the top view of processing reinforcing ribs on the ultra-high strength steel plate in the present invention;

[0027] Figure 3 For Figure 2Cross-sectional view A-A in the present invention;

[0028] Figure 4 Is a three-dimensional view of the vehicle body in the present 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 wall reinforcing rib), 5 - vehicle body, 6 - roof, 7 - rear side wall, 8 - bending position, 9 - reinforcing rib forming punch. Specific embodiments

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0031] Ultra-High Strength Steel (UHSS) is a kind of steel with excellent mechanical properties. Its yield strength is usually above 550 MPa, and its tensile strength can exceed 700 MPa, far higher than ordinary steel. This kind of steel mainly relies on the optimization of alloy components and advanced heat treatment processes to achieve high strength characteristics, and can also take into account plasticity and toughness to a certain extent.

[0032] Main types and characteristics of ultra-high strength steel plates:

[0033] 1. Low-alloy ultra-high strength steel: Composition: Based on carbon, alloy elements such as chromium, nickel, and molybdenum are added. Characteristics: The yield strength is between 550 - 1500 MPa, with good welding performance, suitable for manufacturing aircraft landing gears, rocket engine casings, etc.

[0034] 2. Dual-phase steel (DP steel): Composition: Mainly composed of ferrite and martensite. Characteristics: The yield strength is in the range of 350 - 1000 MPa, with a high elongation rate, very suitable for automotive body structural parts, and can achieve the unity of lightweight and high safety.

[0035] 3. Martensitic steel (MS steel): Composition: After quenching treatment, a single martensitic structure is formed. Characteristics: The yield strength can reach over 1500 MPa, but the plasticity is relatively low. It is commonly used in manufacturing automotive bumpers, bulletproof armor, etc.

[0036] 4. Hot-formed steel: Composition: A typical representative is 22MnB5 steel. Characteristics: After high-temperature austenitization and rapid cooling quenching, the yield strength can exceed 1000 MPa. It is mainly used in key safety components such as automotive A / B pillars and door anti-collision beams.

[0037] Application fields of ultra-high strength steel plates:

[0038] Automotive industry: Ultra-high strength steel plates are widely used in automotive manufacturing, such as in body frames, chassis parts, airbag brackets, etc. It can reduce the body weight, thereby reducing fuel consumption, and at the same time improve the collision safety of the vehicle.

[0039] Aerospace field: In aerospace, it is mainly used in aircraft structural parts, landing gears, engine components, etc., which helps to reduce weight while ensuring strength and improve flight efficiency.

[0040] Military field: It can be used to manufacture bulletproof vehicles, armor plates, artillery barrels, etc., which can resist high impact forces.

[0041] Construction machinery industry: Equipment such as the buckets of excavators and the booms of cranes also use ultra-high strength steel plates to cope with heavy-duty working conditions.

[0042] Currently, the development trend of ultra-high strength steel plates mainly focuses on further improving strength and formability, such as the third-generation automotive steels (QP steel, TWIP steel, etc.). In addition, attention is also paid to the adoption of environmentally friendly processes, such as chromium-free passivation treatment, to reduce environmental pollution.

[0043] As Figure 1 As shown in FIG. -3, in some embodiments, the ultra-high strength steel plate forming method designed by the present invention is mainly aimed at dual-phase steel (DP steel), martensitic steel (MS steel), and hot-formed steel. The steps include steel plate cutting, steel plate bending, steel plate repair welding, and steel plate welding.

[0044] Example 1

[0045] Steel plate cutting implementation example:

[0046] Combined with Figure 1 As shown in the ultra-high strength steel plate cutting schematic diagram, the specific operation steps are as follows:

[0047] 1. Material preparation: Select an ultra-high strength steel plate with a thickness of 8 mm for bulletproof level (tensile strength

[0048] ≥1200 MPa), clean the surface to remove oil;

[0049] 2. Cutting parameter setting: Use an 8000W fiber laser cutting machine, with a distance of 0.8 mm between the cutting head and the steel plate, and a cutting air pressure of 0.8 MPa;

[0050] 3. Cutting seam processing: Cut four long cutting seams (length 500 mm, width 0.8 mm) longitudinally along the steel plate, and symmetrically cut four groups of short cutting seams (length 50 mm, perpendicular to the long seam, width 0.6 mm) at both ends of the long cutting seams;

[0051] 4. Quality inspection: Use an electron microscope to detect the width of the cutting seam (≤1 mm) to ensure no slag residue.

[0052] Example 2

[0053] Steel plate bending forming process:

[0054] Refer to Figure 2 —3 Schematic diagram of stiffener forming, and the specific operations include:

[0055] 1. Die installation: Install a special stiffener forming punch 9 (inclination angle 45°, R corner radius 3 mm) on a hydraulic bending machine;

[0056] 2. Positioning and pressing:

[0057] Position the cut steel plate on the female die, align the cutting seam with the center line of the punch, apply a pressure of 300T for cold stamping, and the holding time is 15 seconds;

[0058] 3. Stiffener forming:

[0059] Form continuous stiffeners with a height a = 8 mm (corresponding width b = 50 mm, meeting the constraint), and control the surface roughness of the bending area below Ra3.2 μm.

[0060] Example 3

[0061] Combined with Figure 2 the stiffener cross-section structure in, implement the repair welding process:

[0062] 1. Pretreatment before welding: Use an angle grinder to clean the root of the stiffener, form a 30° groove, and use acetone to wipe and remove the oxide layer;

[0063] 2. Welding operation: Use MAG welding (shielding gas ratio Ar80% + CO220%), welding current 150A, voltage 22V, wire diameter 1.2 mm (ER120S-G), multi-layer and multi-pass welding, and the width of a single-pass weld ≤ 3.5 mm;

[0064] 3. Post-weld treatment: Tap the weld seam to eliminate stress, and conduct penetrant testing to confirm no cracks.

[0065] Example 4

[0066] Thick plate welding process (taking a thickness of 6 mm as an example), refer to Figure 3 Welding structure schematic diagram:

[0067] 1. Groove machining: Adopt a V-shaped 60° groove (root face 0.5 mm), assembly gap 1.5 mm, misalignment ≤ 0.3 mm;

[0068] 2. Preheating treatment: Inductively heat to 100 °C by electromagnetic induction, preheating range 50 mm, and use an infrared thermometer to monitor the temperature in real time;

[0069] 3. Welding implementation: Root pass welding: ER70S-G welding wire, current 90 A, voltage 19 V, welding speed 18 cm / min, fill pass welding: ER70S-G welding wire, current 160 A, voltage 23 V, welding speed 25 cm / min, interpass temperature controlled within 100 °C;

[0070] 4. Post-weld heat treatment: Locally inductively heat to 150 °C (±5 °C), hold for 1 hour, and air cool.

[0071] Example 5

[0072] Application of body panels for armored vehicles: Such as Figure 4 The structure of the body panel shown:

[0073] 1. Roof reinforcement layout: Arrange 5 parallel reinforcements (spacing 300 mm), the direction of the reinforcement body is parallel to the roof longitudinal beam, and the end is 50 mm from the side line;

[0074] 2. Rear side panel reinforcement design: Vertically arrange 3 height reinforcements (spacing 400 mm), and the lower end of the reinforcement body extends 30 mm above the wheel arch;

[0075] 3. Comprehensive performance verification: Flatness detection: Fluctuation within 3 m length ≤ 1.5 mm, bulletproof test: Can resist 7.62 mm armor-piercing bullets (distance 30 m, incident angle 60°), salt spray test: No red rust generated after 1000 hours.

[0076] In summary, the present invention solves the problem of complex processes caused by the high stiffness and difficult forming of ultra-high strength steel plate 1. Through simple processes, complex shapes are achieved, problems such as large plane deformation and water accumulation and corrosion are controlled, and the reliability of armored vehicles is improved. The present invention provides an efficient, economical and reliable solution for the application of ultra-high strength steel plate 1 in body panels through the combination of structural innovation and process optimization.

[0077] Here, it should be noted that the description of the above technical solutions is exemplary. This specification can be embodied in different forms and should not be construed as limited to the technical solutions set forth herein. On the contrary, providing these descriptions will make the disclosure of the present invention thorough and complete, and will fully convey the scope disclosed in this specification to those skilled in the art. In addition, the technical solutions of the present invention are only defined by the scope of the claims. The shapes, sizes, ratios, angles, and numbers disclosed for various aspects of this specification and the claims are merely examples. Therefore, this specification and the claims are not limited to the details shown. In the following description, when the detailed description of related known functions or configurations is determined to unnecessarily obscure the focus of this specification and the claims, the detailed description will be omitted. When using "including", "having", and "comprising" described in this specification, there may also be another part or other parts, and the terms used can generally be singular but can also represent plural forms.

[0078] Finally, it should be pointed out that the above embodiments are only relatively representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and there can be many variations. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention should be considered to fall within the protection scope of the present invention.

Claims

1. A method for forming an ultra-high strength steel plate, characterized in that: It includes steel plate cutting, steel plate bending and steel plate repair welding; The steel plate cutting includes cutting cutting seams with specific shapes on the ultra-high strength steel plate (1); The steel plate bending includes bending the cut ultra-high strength steel plate (1) and stamping at the cutting seams to form raised reinforcing ribs (4) at the cutting seams; The steel plate repair welding includes repair welding the cutting seams of the reinforcing ribs (4).

2. The method for forming an ultra-high strength steel sheet according to claim 1, characterized in that: The method of the steel plate cutting includes cutting one or more of the cutting seams with specific shapes on the ultra-high strength steel plate (1) by laser or water jet.

3. The method for forming an ultra-high strength steel plate according to claim 1 or 2, characterized in that: The cutting seams with specific shapes include long cutting seams (2) and short cutting seams (3) symmetrically arranged at both ends of the long cutting seams (2) and perpendicularly intersecting the long cutting seams (2).

4. The method for forming an ultra-high strength steel sheet according to claim 3, characterized in that: The weld widths of the long cutting seams (2) and the short cutting seams (3) are both not greater than 1 mm.

5. The method for forming an ultra-high strength steel sheet according to claim 1, characterized in that: The weld width of the cutting seams of the reinforcing ribs (4) is not greater than 4 mm.

6. The method for forming an ultra-high strength steel plate according to claim 1 or 5, characterized in that: The convex height a of the reinforcing rib (4) and the convex width b of the reinforcing rib have the following corresponding relationship:

7. The high-strength steel sheet forming method according to claim 1, characterized in that: It also includes steel plate welding, and the steel plate welding includes beveling, welding, heating and cooling; The beveling includes: for the ultra-high strength steel plate (1) with a thickness less than 2 - 6 mm, opening a V-shaped 60° bevel, with a root face of 0.5 mm, a fit-up gap of 1.5 mm, and a misalignment ≤ 0.3 mm; The welding includes: preheating treatment before welding, with a preheating temperature of 100 °C and a preheating range of 50 mm around the weld; controlling the interpass temperature within 100 °C; using ER70S-G welding wire for the root pass welding, with a welding current of 90 A, a welding voltage of 19 V, and a welding speed of 18 cm / min; using ER70S-G welding wire for the filler pass welding, with a welding current of 160 A, a welding voltage of 23 V, and a welding speed of 25 cm / min; The heating and cooling includes: heating the welded part to 150 ± 5 °C, keeping it warm for 1 h, and air cooling.

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

9. The body panel made by the method of forming an ultra-high strength steel sheet as claimed in claim 8, wherein: The reinforcing ribs (4) include multiple roof reinforcing ribs (4.1) arranged on the roof (6), spaced and parallel along the vehicle body width direction, and the roof reinforcing ribs (4.1) are arranged along the vehicle body length direction.

10. The body panel made by the ultra-high strength steel sheet forming method as claimed in claim 8 or 9, characterized in that: The reinforcing ribs (4) include multiple rear side panel reinforcing ribs (4.2) arranged on the rear side panel (7), spaced and parallel along the vehicle body width direction, and the rear side panel reinforcing ribs (4.2) are arranged along the vehicle body height direction.

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