High-strength steel stamping forming process
By combining zoned blank holder force control, dynamic pressure-increasing deep drawing, step-by-step flanging, and conformal support structure, the cracking and welding strength attenuation problems of high-strength steel fork-shaped control arms have been solved, achieving lightweight and high-reliability forming of fork-shaped control arms.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGZHOU ZHONGYI MACHINERY
- Filing Date
- 2026-05-25
- Publication Date
- 2026-07-03
Smart Images
Figure CN122322833A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of metal processing, and more particularly to a high-strength steel stamping process. Background Technology
[0002] The wishbone control arm (also known as an A-arm) is a core guiding and load-bearing component of the automotive suspension system, widely used in mid-to-high-end models and new energy vehicles. This component typically has three connection points (two bushing mounting points and one ball joint mounting point), and must simultaneously withstand longitudinal forces, lateral forces, and torsional moments during operation, requiring extremely high rigidity, strength, and fatigue life. Currently, the mainstream manufacturing process for wishbone control arms is casting, using methods such as sand casting, metal mold casting, or low-pressure casting to create a one-piece arm body with complex curved surfaces and internal reinforcing ribs. This process can directly obtain a near-net-shape three-dimensional structure without subsequent welding, resulting in strong integrity, and has therefore been widely adopted in the industry for a long time. However, all of the above-mentioned existing technologies have insurmountable drawbacks. To ensure that molten iron or aluminum completely fills the mold cavity and avoids casting defects such as shrinkage porosity and gas holes in thin-walled areas, the actual wall thickness in the casting process is usually no less than 5-6 mm. This results in a lower limit that is difficult to break through for the weight of the fork arm, which cannot meet the lightweight requirements of new energy vehicles that are extremely sensitive to driving range. At the same time, the elongation of the casting material is generally low, and the material exhibits obvious brittle characteristics. When subjected to extreme impact loads such as wheel impacts with road shoulders or deep potholes, it is prone to brittle fracture without warning, posing a significant safety hazard. While existing high-strength steel stamping and welding processes offer potential for lightweighting, they still face two major challenges when applied to fork-shaped control arms: First, high-strength steel has limited elongation, while fork-shaped arms have complex deep-drawn curved surfaces and areas of severe local deformation. During stamping, cracks are easily generated at the punch fillets and sidewalls, resulting in a low stamping yield. Second, the main plate and sub-plate need to be welded around their perimeters after stamping to form a closed section. However, the welding heat input can cause martensitic tempering or grain coarsening in the heat-affected zone, resulting in a strength reduction rate as high as 20%-30%. This makes the welded joint a weak point in the entire structure, prone to failure under alternating fatigue loads.
[0003] Therefore, how to develop a high-strength steel stamping process that can simultaneously solve the problems of high-strength steel stamping cracking and welding strength attenuation, and can replace traditional casting forming to achieve lightweight, highly reliable, and low-cost manufacturing of fork-shaped control arms, is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0004] To address the aforementioned problems in the existing technology, this invention proposes a high-strength steel stamping process, the specific technical solution of which is as follows: The present invention provides a high-strength steel stamping process, comprising the following steps: S1: Blanking and billet optimization, which punches high-strength steel plates into billets with a predetermined outline; S2: Deep drawing, using a blank holder with independently controlled blank holder force in each zone to deep draw the blank, the blank holder includes at least a first blank holder area corresponding to the first branch flange area of the fork-shaped control arm, a second blank holder area corresponding to the second branch flange area, and a third blank holder area corresponding to the central connection area; during the deep drawing stroke, the blank holder force of the first blank holder area and the second blank holder area are controlled to be less than the blank holder force of the third blank holder area, and in the later stage of the deep drawing stroke, dynamic pressure is applied to at least one of the first blank holder area and the second blank holder area, the pressure increase rate of the dynamic pressure is inversely proportional to the displacement of the deep drawing stroke; S3: Flanging and Hole Punching. The workpiece after step S2 is flanged in stages. First, a first flanging punch is used to pre-flang the bifurcation area of the workpiece along the first flanging direction. The first flanging direction has a first spatial angle with the main punching direction. Then, a second flanging punch is used to perform final flanging along the second flanging direction. The second flanging direction has a second spatial angle with the main punching direction. The first spatial angle is different from the second spatial angle. A conformal support structure is provided on the working surface of the first flanging punch. The geometry of the conformal support structure is conformal to the inner curved surface of the bifurcation area. S4: Welding and heat input control, which involves welding the main board and sub-board after the processing in step S3 and controlling the welding heat input; S5: Springback compensation and dimensional accuracy, springback compensation and correction are performed on the welded components; S6: Fatigue and strength consistency treatment, surface treatment of the corrected component.
[0005] As a further embodiment of the present invention, in step S2, the blank-pressing force of the first blank-pressing area and the second blank-pressing area changes with the drawing stroke in a gradient decreasing curve, while the blank-pressing force of the third blank-pressing area changes with the drawing stroke in a gradient increasing curve.
[0006] As a further aspect of the present invention, in step S2, the starting trigger point of the dynamic pressurization is located within the latter 20%-30% of the drawing stroke, and the pressure amplitude of the dynamic pressurization is associated with the maximum thinning rate detection value of the first or second edge pressing zone during the middle stage of drawing.
[0007] As a further embodiment of the present invention, in step S2, a local drawing rib is also provided on the blank holder. The local drawing rib is only arranged on the blank holder surface corresponding to the third blank holder area, while the blank holder surfaces corresponding to the first blank holder area and the second blank holder area are smooth blank holder surfaces.
[0008] As a further aspect of the present invention, in step S3, the first flanging direction is the direction of the angle bisector of the two branches of the fork-shaped control arm, and the second flanging direction is perpendicular to the main stamping direction.
[0009] As a further embodiment of the present invention, in step S3, the conformal support structure of the first flanging punch is an elastic floating insert or a replaceable carbide pad, and the outer contour surface of the elastic floating insert or replaceable carbide pad and the inner curved surface of the bifurcation area maintain zero-gap contact at the start of the pre-flanging.
[0010] As a further embodiment of the present invention, in step S3, a local heating step is inserted between the pre-flanging and the final flanging. The local heating step is applied only to the flanging outline area of the bifurcation zone, and the heating temperature is set to be lower than the martensitic transformation initiation point of the high-strength steel.
[0011] As a further aspect of the present invention, the pressure boosting rate of the dynamic pressure boosting in step S2 and the flanging speed of the pre-flanging in step S3 satisfy the following relationship: the ratio of the pressure boosting rate of the dynamic pressure boosting to the flanging speed of the pre-flanging decreases monotonically as the drawing stroke progresses.
[0012] As a further aspect of the present invention, in step S2, the pressing forces of the first pressing area and the second pressing area are controlled independently, and the ratio of the pressing forces of the two is equal to the length ratio of the first branch to the second branch of the fork-shaped control arm.
[0013] As a further aspect of the present invention, the welding in step S4 is performed using laser welding, and the welding heat input is limited by controlling the ratio of laser power to welding speed. The ratio of laser power to welding speed changes as the weld seam extends along the bifurcation zone of the fork-shaped control arm.
[0014] The beneficial effects of this invention are as follows: By combining the zoned blank holder force control in step S2 with the subsequent dynamic pressurization, the cracking problem of high-strength steel in complex fork-shaped deep drawing is solved; by combining the step-by-step flanging with the conformal support structure in step S3, the instability problem of the low-stiffness structure in the bifurcation area during spatial flanging is solved. The technical features of the two steps are interrelated: In step S2, dynamic pressurization optimizes the material distribution and residual stress state in the bifurcation area, providing a more uniform initial stress field for the flanging in step S3; the reaction force of the conformal support structure in step S3 further consolidates the shape accuracy established in step S2. The synergistic effect of the two enables the overall process to stably form a high-strength steel fork-shaped control arm. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a flowchart of the steps of the present invention. Detailed Implementation
[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] Please see Figure 1 The present invention provides a high-strength steel stamping process, comprising the following steps: S1: Blanking and billet optimization: High-strength steel plates are punched into billets with a predetermined profile. The profile of the billet is optimized based on the unfolded shape of the fork-shaped control arm. The billet boundary is determined by finite element simulation to reduce material accumulation or excessive thinning during subsequent deep drawing.
[0019] S2: Deep drawing, using a blank holder with independently controlled blank holder force in each zone to deep draw the blank, the blank holder includes at least a first blank holder area corresponding to the first branch flange area of the fork-shaped control arm, a second blank holder area corresponding to the second branch flange area, and a third blank holder area corresponding to the central connection area; during the deep drawing stroke, the blank holder force of the first blank holder area and the second blank holder area are controlled to be less than the blank holder force of the third blank holder area, and in the later stage of the deep drawing stroke, dynamic pressure is applied to at least one of the first blank holder area and the second blank holder area, the pressure increase rate of the dynamic pressure is inversely proportional to the displacement of the deep drawing stroke; The independent control of the blank holder force is achieved through the following method: the first, second, and third blank holder zones of the blank holder ring are each connected to an independent hydraulic cylinder or servo motor drive mechanism, and the pressure in each zone can be adjusted independently. During the drawing stroke, the blank holder forces in the first and second blank holder zones are controlled to be less than those in the third blank holder zone. This is because during the drawing process of the fork-shaped control arm, the central connecting zone requires a larger blank holder force to suppress wrinkling, while the flange zones of the two branches require a smaller blank holder force to allow material to flow into the cavity, avoiding cracking due to excessive flow resistance.
[0020] Furthermore, in the later stages of the drawing stroke, dynamic pressure is applied to at least one of the first and second blank holder regions. The rate of dynamic pressure increase is inversely proportional to the displacement of the drawing stroke. Specifically, as the drawing stroke approaches its end, the displacement increment decreases, and the pressure increase rate increases accordingly; conversely, in the initial stage of the later stages of the drawing stroke, the displacement is larger, and the pressure increase rate is lower. This inverse relationship is achieved through a preset function curve in the controller, such as a linear or exponential inverse relationship.
[0021] In the later stages of deep drawing, the material has largely adhered to the die, and the material flow at the two branch ends tends to stop. At this point, applying dynamic pressure forces the material to generate localized micro-flow in the final stage to fill the root of the punch fillet, preventing loosening or wrinkling caused by material suspension. The design, where the pressure increase rate is inversely proportional to the displacement, ensures that when the material flow space is extremely small at the end of the stroke, the pressure can be rapidly increased to produce sufficient shaping effect, while avoiding premature pressure increase that could cause the material to tear.
[0022] S3: Flanging and Hole Punching. The workpiece after step S2 is flanged in stages. First, a first flanging punch is used to pre-flang the bifurcation area of the workpiece along the first flanging direction. The first flanging direction has a first spatial angle with the main punching direction (i.e., the movement direction of the punch in step S2, usually the vertical direction), for example, 30°~60°. Then, a second flanging punch is used to perform final flanging along the second flanging direction. The second flanging direction has a second spatial angle with the main punching direction. The first spatial angle is different from the second spatial angle, for example, the second spatial angle is 90°. A conformal support structure is provided on the working surface of the first flanging punch. The geometry of the conformal support structure is conformal with the inner curved surface of the bifurcation area. That is, the outer surface of the support structure is geometrically perfectly matched (conformal) with the inner curved surface of the bifurcation area of the fork-shaped control arm. The gap between the two is 0-0.05mm at the beginning of the pre-flanging.
[0023] Because the bifurcation section of the forked control arm has a low moment of inertia and weak stiffness, and because there is a spatial angle between the flanging direction and the main stamping direction, a direct single flanging would lead to secondary deformation superimposed with residual stamping stress, causing local instability (wrinkling or collapse). This step adopts a step-by-step flanging process: the first step is to pre-flanging along the smaller spatial angle to gradually guide the material deformation; the second step is to complete the flanging along the final direction. During the pre-flanging process, the conformal support structure supports the bifurcation area from the inside, preventing it from concave inward or becoming unstable under the flanging pressure, thus ensuring the clarity and dimensional accuracy of the flanging contour.
[0024] S4: Welding and heat input control, which involves welding the main board and sub-board after the processing in step S3 and controlling the welding heat input; S5: Springback compensation and dimensional accuracy, springback compensation and correction are performed on the welded components; specifically, a bending correction mold or a local shaping mold can be used to compensate for dimensional deviations caused by the release of residual stress, so that the final product meets the drawing requirements.
[0025] S6: Fatigue and strength consistency treatment, surface treatment of the corrected component.
[0026] By combining zoned blank holder force control in step S2 with dynamic pressurization in the subsequent process, the cracking problem of high-strength steel in complex fork-shaped deep drawing was solved. Similarly, by combining step-by-step flanging with a conformal support structure in step S3, the instability problem of the low-stiffness structure in the bifurcation area during spatial flanging was resolved. The technical features of the two steps are interrelated: dynamic pressurization in S2 optimizes the material distribution and residual stress state in the bifurcation area, providing a more uniform initial stress field for flanging in S3; the reaction force of the conformal support structure in S3 further consolidates the shape accuracy established in S2. Their synergistic effect enables the overall process to stably form a high-strength steel fork-shaped control arm.
[0027] As a further embodiment of the present invention, in step S2, the blank-pressing force of the first blank-pressing area and the second blank-pressing area changes with the drawing stroke in a gradient decreasing curve, while the blank-pressing force of the third blank-pressing area changes with the drawing stroke in a gradient increasing curve.
[0028] The gradient descent curve refers to the phenomenon where, as the drawing punch moves downward, the blank holder force in the first and second blank holder zones gradually decreases according to a preset slope. For example, the pressure decreases by 2%-5% for every 1mm decrease in stroke. Similarly, the gradient ascent curve shows that the blank holder force in the third blank holder zone gradually increases.
[0029] In the initial stage of deep drawing, a large blank holder force is required to establish sufficient friction and prevent material from flowing in too quickly and causing wrinkling. As deep drawing progresses, the material gradually hardens and flow resistance increases. At this point, the blank holder force in the first and second blank holder zones needs to be reduced to allow the material to continue flowing into the deep cavity region, avoiding cracking due to insufficient flow. The third blank holder zone corresponds to the central connecting area, which is prone to wrinkling in the later stages of deep drawing. Therefore, the blank holder force needs to be gradually increased to suppress wrinkling. By using a gradient change rather than a constant blank holder force, the different requirements for material flow control at different stages of deep drawing are better matched, further improving process stability.
[0030] As a further aspect of the present invention, in step S2, the starting trigger point of the dynamic pressurization is located within the latter 20%-30% of the drawing stroke, and the pressure amplitude of the dynamic pressurization is associated with the maximum thinning rate detection value of the first or second edge pressing zone during the middle stage of drawing.
[0031] The total drawing stroke is denoted as H, and the latter 20%-30% of the stroke is between 0.7H-0.8H and H. Dynamic pressure is triggered at a preset position within this range (e.g., 0.75H). During the mid-drawing stage (e.g., 0.3H-0.6H), the material thinning rate at the corresponding position of the first or second pressure zone is detected in real time by a sensor and denoted as δ_max. The pressure amplitude ΔP of the dynamic pressure boost is calculated according to the formula ΔP = k·δ_max, where k is a preset coefficient (e.g., 0.5~2.0 MPa / %).
[0032] The maximum thinning rate in the mid-stage reflects the degree of material danger in that region—the greater the thinning rate, the closer that region is to the cracking limit. The pressure amplitude of the dynamic pressurization in the later stage is related to this thinning rate, realizing closed-loop adaptive control: when the thinning is severe, a smaller pressurization amplitude is used to avoid overload cracking; when the thinning is minor, a larger pressurization amplitude can be used to enhance the shaping effect.
[0033] As a further embodiment of the present invention, in step S2, a local drawing rib is also provided on the blank holder. The local drawing rib is only arranged on the blank holder surface corresponding to the third blank holder area, while the blank holder surfaces corresponding to the first blank holder area and the second blank holder area are smooth blank holder surfaces.
[0034] The draw beads are raised strips with semi-circular or trapezoidal cross-sections, arranged circumferentially along the surface of the blank holder in the third blank holder area. The surfaces of the first and second blank holder areas are precision ground to a surface roughness Ra≤0.4μm, resulting in smooth blank holder surfaces. The draw beads are used to increase the material flow resistance. Placing draw beads in the central connecting area (third blank holder area) increases the flow resistance in this area, and combined with the larger blank holder force in this area, effectively suppresses wrinkling. In the two branch flange areas (first and second blank holder areas), smooth blank holder surfaces are used, combined with a smaller blank holder force, to minimize flow resistance and promote material flow into the cavity. The differentiated arrangement of the draw beads further strengthens the logical consistency of the zoned control, making the functional division between the central area's "flow obstruction" and the branch areas' "flow promotion" more clearly defined.
[0035] As a further aspect of the present invention, in step S3, the first flanging direction is the direction of the angle bisector of the two branches of the fork-shaped control arm, and the second flanging direction is perpendicular to the main stamping direction.
[0036] The two branches of the forked control arm form a certain angle (e.g., 60°-120°), and the direction of the angle bisector is the first flanging direction. The direction perpendicular to the main stamping direction (assuming the main stamping direction is vertical) is the horizontal direction, serving as the second flanging direction. The first flanging direction, along the angle bisector, effectively distributes the flanging force along the extension directions of the two branches, allowing the material to flow along the symmetry axis of the two branches during the pre-flanging stage, resulting in gentler deformation and preventing twisting of the other branch due to flanging directly along one branch direction. The second flanging direction is perpendicular to the main stamping direction, which is the flanging posture required for the final product.
[0037] As a further embodiment of the present invention, in step S3, the conformal support structure of the first flanging punch is an elastic floating insert or a replaceable carbide pad, and the outer contour surface of the elastic floating insert or replaceable carbide pad and the inner curved surface of the bifurcation area maintain zero-gap contact at the start of the pre-flanging.
[0038] The elastic floating insert consists of a base, a spring or polyurethane elastomer, and a conformal working surface. When the first flanging punch moves downward, the conformal working surface first contacts the curved surface within the bifurcation zone, maintaining zero-gap contact (gap = 0) under the spring force. The replaceable carbide gasket is a fixed structure, with high-precision machining ensuring that its outer contour surface is completely consistent with the theoretical shape of the curved surface within the bifurcation zone, and the gap between them at the initial flanging moment is 0-0.02mm. Zero-gap contact ensures that the inner wall of the bifurcation zone is rigidly supported at the initial moment of flanging force application. For the elastic floating insert, the spring force provides initial support and allows automatic gap compensation after the working surface wears; for the carbide gasket, its high hardness and high wear resistance ensure dimensional stability during long-term use.
[0039] Both implementation methods have their advantages: floating inserts are suitable for applications with large batch sizes and rapid mold wear; carbide liners are suitable for applications with extremely high precision requirements. Zero-gap contact fundamentally eliminates the risk of instability and collapse of the inner wall during flanging.
[0040] As a further embodiment of the present invention, in step S3, a local heating step is inserted between the pre-flanging and the final flanging. The local heating step is applied only to the flanging outline area of the bifurcation zone, and the heating temperature is set to be lower than the martensitic transformation initiation point of the high-strength steel.
[0041] A high-frequency induction heating coil or laser heating head is used to locally heat the flange contour line of the bifurcation area. The heating temperature is controlled in a closed loop by an infrared thermometer and set to 30-50℃ below the Ms point (for example, for steel with an Ms point of 380℃, heating to 330-350℃). The heating time is 1-3 seconds, followed immediately by the final flange turning.
[0042] After pre-flanging, significant work hardening and residual stress remain in the flanging contour area. Local heating below the Ms point allows the material to recover (dynamic recovery), eliminating some of the residual stress and simultaneously reducing the yield strength by approximately 20%-30%, thus improving the material's plastic deformation capacity without undergoing martensitic phase transformation (avoiding microstructural changes). This makes the material flow more easily during final flanging, reducing the risk of cracking.
[0043] As a further aspect of the present invention, the pressure boosting rate of the dynamic pressure boosting in step S2 and the flanging speed of the pre-flanging in step S3 satisfy the following relationship: the ratio of the pressure boosting rate of the dynamic pressure boosting to the flanging speed of the pre-flanging decreases monotonically as the drawing stroke progresses.
[0044] Let the boost rate of dynamic boosting be R_p (unit: MPa / mm stroke), and the flanging speed of pre-flanging be V_f (unit: mm / s). Define the ratio K = R_p / V_f. In the later stage of the drawing stroke (from the trigger point to the end point), the value of K monotonically decreases, for example, from the initial 0.5 to the end point 0.1. Monotonically decreasing can be achieved through a linear function, an exponential function, or a piecewise constant.
[0045] This relationship establishes the coupling of process parameters between steps S2 and S3. In the early stages of deep drawing (near the trigger point), R_p is relatively large while V_f is relatively small (pre-flanging has not yet started or has just begun), and the K value is relatively large. At this time, the dynamic pressure increase of S2 dominates, mainly completing the shaping of the final stage of deep drawing. As deep drawing progresses to the end, R_p gradually decreases, while pre-flanging begins, V_f increases, and the K value decreases, meaning that the flanging effect of S3 gradually replaces the shaping effect of S2, achieving a smooth transition between process steps. Through parameter coupling, stress abrupt changes or deformation inconsistencies caused by abrupt changes in process parameters in S2 and S3 are avoided, making the deformation history and stress history of the entire forming process continuous and coordinated, which is beneficial to the dimensional accuracy and mechanical property consistency of the final product.
[0046] As a further aspect of the present invention, in step S2, the pressing forces of the first pressing area and the second pressing area are controlled independently, and the ratio of the pressing forces of the two is equal to the length ratio of the first branch to the second branch of the fork-shaped control arm.
[0047] Let the length of the first branch be L1 and the length of the second branch be L2. Then the blank holder force F1 in the first blank holder region and the blank holder force F2 in the second blank holder region satisfy F1 / F2 = L1 / L2. For example, if L1 = 200mm, L2 = 250mm, and the length ratio L1 / L2 = 0.8, then set F1 / F2 = 0.8, such as F1 = 8kN and F2 = 10kN.
[0048] The longer the branch, the larger the volume of material that needs to flow into the cavity during the drawing process in its flange area. Therefore, a smaller blank holder force is required to reduce flow resistance. Conversely, the shorter the branch, the smaller the required material flow volume, allowing for a larger blank holder force. Setting the blank holder force ratio to the length ratio is a proportional control strategy based on geometric similarity, ensuring that the material flow rate of the two branches matches their required volume.
[0049] As a further aspect of the present invention, the welding in step S4 is performed using laser welding, and the welding heat input is limited by controlling the ratio of laser power to welding speed. The ratio of laser power to welding speed changes as the weld seam extends along the bifurcation zone of the fork-shaped control arm.
[0050] In laser welding, the heat input Q is defined as Q = P / v, where P is the laser power (W) and v is the welding speed (mm / s). The weld is divided into several sections along the weld path in the bifurcation zone, such as the section near the root of the bifurcation, the middle section, and the end section. Different P / v ratios are used for each section. For example, the root section, due to its thicker base material and faster heat dissipation, uses a larger P / v ratio (e.g., 200 J / mm); the end section, with its thinner base material and slower heat dissipation, uses a smaller P / v ratio (e.g., 120 J / mm).
[0051] The cross-sectional thickness, curvature, and heat dissipation conditions of the bifurcation zone of the forked control arm change along the extension direction. A fixed heat input cannot adapt to these changes: excessive heat input can lead to softening of the heat-affected zone, while insufficient heat input results in insufficient penetration. By changing the P / v ratio along the weld direction, the heat input is matched with the local structural characteristics, ensuring consistent penetration throughout the weld and uniform performance of the heat-affected zone.
[0052] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
Claims
1. A high-strength steel press forming process, characterized by, Includes the following steps: S1: Blanking and billet optimization, which punches high-strength steel plates into billets with a predetermined outline; S2: Deep drawing, using a blank holder with independently controlled blank holder force in each zone to deep draw the blank, the blank holder includes at least a first blank holder area corresponding to the first branch flange area of the fork-shaped control arm, a second blank holder area corresponding to the second branch flange area, and a third blank holder area corresponding to the central connection area; during the deep drawing stroke, the blank holder force of the first blank holder area and the second blank holder area are controlled to be less than the blank holder force of the third blank holder area, and in the later stage of the deep drawing stroke, dynamic pressure is applied to at least one of the first blank holder area and the second blank holder area, the pressure increase rate of the dynamic pressure is inversely proportional to the displacement of the deep drawing stroke; S3: Flanging and Hole Punching. The workpiece after step S2 is flanged in stages. First, a first flanging punch is used to pre-flang the bifurcation area of the workpiece along the first flanging direction. The first flanging direction has a first spatial angle with the main punching direction. Then, a second flanging punch is used to perform final flanging along the second flanging direction. The second flanging direction has a second spatial angle with the main punching direction. The first spatial angle is different from the second spatial angle. A conformal support structure is provided on the working surface of the first flanging punch. The geometry of the conformal support structure is conformal to the inner curved surface of the bifurcation area. S4: Welding and heat input control, which involves welding the main board and sub-board after the processing in step S3 and controlling the welding heat input; S5: Springback compensation and dimensional accuracy, springback compensation and correction are performed on the welded components; S6: Fatigue and strength consistency treatment, surface treatment of the corrected component.
2. The high-strength steel press forming process of claim 1, wherein: In step S2, the blank-pressing force in the first and second blank-pressing areas changes with the drawing stroke in a gradient decreasing curve, while the blank-pressing force in the third blank-pressing area changes with the drawing stroke in a gradient increasing curve.
3. The high-strength steel stamping process of claim 1, wherein: In step S2, the starting trigger point of the dynamic pressurization is located in the latter 20%-30% of the drawing stroke, and the pressure amplitude of the dynamic pressurization is associated with the maximum thinning rate detection value of the first or second edge pressing zone during the middle stage of drawing.
4. The high-strength steel stamping process according to claim 2, characterized in that: In step S2, a local drawing bead is also provided on the blank holder. The local drawing bead is only arranged on the surface of the blank holder corresponding to the third blank holder area, while the surfaces of the blank holders corresponding to the first blank holder area and the second blank holder area are smooth blank holder surfaces.
5. The high-strength steel stamping process according to claim 3, characterized in that: In step S3, the first flanging direction is the direction of the angle bisector of the two branches of the forked control arm, and the second flanging direction is perpendicular to the main stamping direction.
6. The high-strength steel stamping process according to claim 4, characterized in that: In step S3, the conformal support structure of the first flanging punch is an elastic floating insert or a replaceable carbide pad. The outer contour surface of the elastic floating insert or the replaceable carbide pad maintains zero-gap contact with the inner curved surface of the bifurcation area at the start of the pre-flanging.
7. The high-strength steel stamping process according to claim 5, characterized in that: In step S3, a local heating step is inserted between the pre-flanging and the final flanging. The local heating step only acts on the flanging outline area of the bifurcation zone, and the heating temperature is set to be lower than the martensitic transformation starting point of the high-strength steel.
8. The high-strength steel stamping process according to claim 6, characterized in that: The following relationship exists between the boosting rate of the dynamic boosting in step S2 and the flanging speed of the pre-flanging in step S3: the ratio of the boosting rate of the dynamic boosting to the flanging speed of the pre-flanging decreases monotonically as the drawing stroke progresses.
9. The high-strength steel stamping process according to claim 7, characterized in that: In step S2, the pressing forces of the first pressing area and the second pressing area are controlled independently, and the ratio of their pressing forces is equal to the length ratio of the first branch to the second branch of the fork-shaped control arm.
10. The high-strength steel stamping process according to claim 8, characterized in that: The welding in step S4 is performed using laser welding, and the welding heat input is limited by controlling the ratio of laser power to welding speed. The ratio of laser power to welding speed changes as the weld seam extends along the bifurcation zone of the fork-shaped control arm.