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CN-121988664-A - Composite forming process for plate pre-drawing and die-free mirror image loading and product

CN121988664ACN 121988664 ACN121988664 ACN 121988664ACN-121988664-A

Abstract

The invention discloses a composite forming process and product for plate pre-drawing and die-free mirror image loading, belongs to the technical field of metal component forming and manufacturing, and is used for solving the problems of cracking, thinning out-of-tolerance, low dimensional accuracy and the like of high-strength aluminum alloy thin-wall components with local continuous large-area protrusions and local large-wall angle characteristics in the aerospace field in the forming process. According to the invention, through two-stage area expansion distribution, the thinning amount of each stage is effectively controlled, and the cracking problem caused by one-time large deformation in a single process is avoided. The mirror images are cooperatively loaded on the part of the plate material to form a three-dimensional stress state, so that the forming limit is improved. The in-mold constraint aging synchronization realizes reinforcement and correction, and is obviously superior to the traditional process.

Inventors

  • WANG ZHIHAN
  • WANG ZIWEN
  • GAO XINYUAN
  • ZHENG KAILUN

Assignees

  • 大连理工大学

Dates

Publication Date
20260508
Application Date
20260126

Claims (10)

  1. 1. The composite forming process for plate pre-drawing and die-free mirror image loading is characterized by comprising the following steps of: S1, preprocessing an initial plate; S2, pre-drawing the plate processed in the step S1 to enable the area of the initial plate to be equal to that of the initial plate To extend to Wherein , Is a first area amplification factor; S3, carrying out mirror image loading forming on the plate subjected to pre-drawing, and carrying out cooperative loading on two sides of the plate by adopting a rigid forming tool and an elastic supporting block to ensure that the area of the plate is To extend to Wherein , Is a second area magnification factor; S4, carrying out in-mold constraint aging treatment on the formed plate; Wherein the method comprises the steps of In the range of 1.0 to 1.25, In the range of 1.0 to 1.18, said And The wall thickness reduction rate of the final formed part is less than or equal to 20 percent.
  2. 2. The process according to claim 1, wherein the pretreatment in S1 comprises: S11, carrying out solid solution treatment on the initial plate; S12, heat preservation; S13, quenching to room temperature.
  3. 3. The process according to claim 2, wherein the solid solution temperature in S1 is 450-500 ℃, the solid solution time is not less than 30min, and the heat preservation time is 20-40 min.
  4. 4. The process according to claim 1, wherein in S2, the pre-stretching comprises: S21, pressurizing and fixing two sides of the edge of the plate; s22, pressurizing one surface of the middle part of the plate to enable the plate to be subjected to deep drawing deformation.
  5. 5. The process according to claim 4, wherein in S22, the pressure applied to the middle of the sheet is 0 to 5 t.
  6. 6. The process of claim 1, wherein S3 comprises: S31, transferring the plate subjected to deep drawing to a die-free mirror image loading device for fixing; s32, respectively controlling the rigid forming tool and the elastic supporting block to carry out mirror image collaborative loading by utilizing double-side six-degree-of-freedom mechanical arms; And S33, gradually forming the preformed piece point by point through track planning.
  7. 7. The process of claim 6, wherein the rigid forming tool in S32 is a rotating ball head tool, the rotational speed is 0-1000 rpm, the feed rate is 1000-2000 mm/min, and the forming force interval is 0-0.5 t.
  8. 8. The process according to claim 1, wherein in S4, the aging temperature is 110 ℃ to 130 ℃, the aging time is 12 to 24 hours, and the blank holder force applied in the aging process is 0 to 5t.
  9. 9. The process of any one of claims 1-8, wherein the starting sheet is a 2xxx series or 7xxx series aluminum alloy.
  10. 10. A product made by the process of any one of claims 1-9, wherein the product is a thin-walled member having a locally continuous large-area raised structure, and the raised structure has at least one of a local fillet ratio r/t less than or equal to 5, a raised aspect ratio H/t greater than or equal to 15, and a local wall angle greater than or equal to 60 °.

Description

Composite forming process for plate pre-drawing and die-free mirror image loading and product Technical Field The invention relates to the technical field of metal member forming and manufacturing, in particular to a composite forming process and a product of plate pre-drawing and die-free mirror image loading. Background In order to solve the problem that the surface of an aircraft door in the aerospace field bears high pneumatic load, the thin-wall member is required to have high structural rigidity, so that a local continuous large-area bulge type structure is often adopted as a reinforcing rib of a new generation aircraft door. The member has the characteristics of complex small characteristics, local small fillet ratio, namely radius to fillet ratio r/t less than or equal to 5, raised height-thickness ratio, namely height-thickness ratio H/t more than or equal to 15, local large wall angle and the like, and has extremely large forming difficulty. Because the aircraft cabin door type structure has extremely high strength requirements on materials, 2xxx and 7xxx series aluminum alloys are often adopted, the weight is reduced as much as possible under the condition of ensuring the strength of the materials, the materials generally have the characteristics of low elastic modulus, large rebound, poor plasticity and the like, and in the traditional manufacturing process, the formed parts generally have the defects of cracking, uneven wall thickness, low dimensional accuracy and the like when manufactured by forming modes such as stamping by paired steel dies, high pressure in a single die, progressive forming and the like. The pair of steel dies (concave/convex dies) depend on full-size cavities to perform one-step press forming on thin plates, and are suitable for conventional metal thin-wall components, but have limited matching degree of material-structure coupling characteristics with high-strength aluminum alloy thin-wall components, namely, near-semi-hard plates are often selected for inhibiting rebound, aluminum alloys such as 2xxx series, 7xxx series and the like have limited room-temperature plasticity and insufficient cold forming elongation, when parts contain small-curvature radius, continuous large-area protrusions, local large-wall angles and other detailed characteristics, the materials are easy to suffer from flow resistance and stress concentration at corners and rib roots and rapidly evolve into macroscopic cracking from microcracks, subsequent heat treatment for reaching T6 strength is superimposed with in-die uneven constraint, residual stress causes component shape distortion and large dimensional accuracy deviation, and the fixed cavities and unified pressing conditions lack of self-adaptive regulation and control on local pressure and pulling-pressing paths, so that uneven thickness, wrinkling and small characteristics (r/T is less than or equal to 5, H/T is high, wall angle is not sufficient, and the like are difficult to meet the requirements of aviation equipment on structural reliability. The single-mode internal high-pressure forming is used as another common thin-wall part forming process, the sheet material is fully filled by relying on high cavity pressure (extremely high pressure is often needed in a small characteristic area such as r/t is less than or equal to 5), ten thousand tons of hydraulic equipment and severe sealing/lubricating conditions are often needed in actual production, high equipment investment and remarkable energy consumption are brought, the ultra-high load amplifies stress gradient at the transition positions of small fillets, ribs and corners, local plastic deformation is easy to induce, microcrack initiation and larger residual stress, the cracking risk of a component is greatly increased, the service life and the dimensional stability of the component are further influenced, meanwhile, the local temperature rise is caused by friction and flow work conversion in the mold filling process, the thermal sensitivity of a superposition material can cause performance fluctuation, thermal deformation and die surface abrasion aggravation, the service life is shortened, and the maintenance cost is pushed up. The progressive forming (single-point/double-point increment type) is carried out layer by a tool head along a preset path without a full-size mould, is suitable for rapid trial production and approximate forming of complex curved surfaces, but is essentially in a process of 'local multi-channel accumulated deep drawing-shearing', is easy to cause non-uniformity of a strain field and migration of thickness to a small curvature radius/transition zone to form a thinning extremum, is more easy to occur for materials with limited elongation and sensitive necking such as high-strength aluminum alloy and limited critical forming angle under local deep drawing and early necking and fine cracking, and is superimposed by time dependence and rebound caused by long-path,