A method and device for controlling ultra-low temperature deformation of an ultra-thin and deep cavity curved aluminum alloy part

Abstract

The present invention provides a method and device for regulating ultra-low temperature deformation of an ultra-thin deep cavity curved aluminum alloy part, relating to the technical field of aluminum alloy forming. The method includes positioning a slab on the upper surface of a sizing die, and pressing down the blank holder and the prefabrication die to clamp the slab; respectively filling ultra-low temperature media into a first cavity of the sizing die and a second cavity of the prefabrication die to cool the first cavity, the second cavity and the slab, compressing the ultra-low temperature media in the first cavity to apply an ultra-low temperature fluid pressure to the slab in the reverse direction to obtain a prefabricated slab; increasing the load of the blank holder, compressing the ultra-low temperature media in the second cavity to apply an ultra-low temperature fluid pressure to the slab in the forward direction, causing the prefabricated slab to be film-coated, stopping filling the ultra-low temperature media, retracting the prefabrication die and the blank holder, relieving the pressure, and taking out the ultra-thin deep cavity curved aluminum alloy part. The slab of the present invention has good cooling effect, uniform temperature distribution, can inhibit the wrinkling of thin plates, reduce cracking, and has uniform wall thickness distribution of components.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy forming, and in particular, to a method and device for regulating ultra-low temperature deformation of ultra-thin and deep cavity curved aluminum alloy parts. Background Art

[0002] Large-sized ultra-thin and deep cavity complex curved components are key structures that make up equipment such as aerospace, satellite communication, and petrochemical industries. Their traditional forming methods have defects such as easy wrinkling, cracking, and uneven wall thickness distribution. Based on the "double-increase effect" that the elongation rate and hardening index of aluminum and aluminum alloy structural materials increase simultaneously at ultra-low temperatures, the method of integral plate ultra-low temperature drawing can form thin-walled curved components without defects. At the same time, setting draw beads and increasing the blank holding force in the ultra-low temperature environment can, to a certain extent, suppress the wrinkling defect. However, for ultra-thin complex curved components with a smaller diameter-thickness ratio (less than 1‰), it is very difficult to form using the thin plate ultra-low temperature drawing method, and problems such as wrinkling, cracking, and uneven wall thickness distribution are inevitably generated during the drawing process, resulting in a small drawing process window and a high rejection rate for the components. In addition, there are process problems such as uneven temperature, low cooling efficiency, and difficulty in reaching the ultra-low temperature critical temperature of the material in a short time during the forming process of ultra-thin components, and the ability to regulate deformation uniformity is very limited. Summary of the Invention

[0003] The problem solved by the present invention is that during the ultra-low temperature drawing process of existing large-sized ultra-thin and deep cavity complex curved components, there is at least one of the problems of easy cracking, easy wrinkling, narrow process window, uneven temperature distribution of the blank, and difficulty in reaching the ultra-low temperature critical transformation temperature of the material, resulting in great difficulty in regulating deformation uniformity.

[0004] To solve the above problems, the present invention provides a method for regulating ultra-low temperature deformation of ultra-thin and deep cavity curved aluminum alloy parts. Based on an ultra-low temperature forming die, the die includes a blank holder, a pre-forming die, and a sizing die, and the blank holder and the pre-forming die are arranged above the sizing die. The method for regulating ultra-low temperature deformation of ultra-thin and deep cavity curved aluminum alloy parts includes the following steps:

[0005] Step S1, positioning the blank on the upper surface of the sizing die, and pressing down the blank holder and the pre-forming die to clamp the blank;

[0006] Step S2, filling ultra-low temperature media into the first cavity of the sizing die and the second cavity of the pre-forming die respectively to cool the first cavity, the second cavity, and the blank;

[0007] Step S3, compressing the ultra-low temperature medium in the first cavity to reversely apply an ultra-low temperature fluid pressure to the blank, and the blank moves towards the second cavity under the action of the ultra-low temperature fluid pressure until it adheres to the second cavity to obtain a pre-formed blank;

[0008] Step S4: Increase the load of the blank holder, compress the cryogenic medium in the second mold cavity to apply a cryogenic fluid pressure to the slab in the forward direction, and the prefabricated slab moves towards the first mold cavity under the action of the cryogenic fluid pressure until it is film-attached, and the pressure is maintained for a preset time.

[0009] Step S5: Stop filling the cryogenic medium, the prefabricated mold and the blank holder return, the pressure is released, and the ultra-thin deep cavity curved aluminum alloy part is taken out.

[0010] Optionally, the cryogenic medium includes liquid oxygen, liquid argon or liquid nitrogen.

[0011] Optionally, the shape of the prefabricated slab is corrugated.

[0012] Optionally, the total surface area of the prefabricated slab satisfies the following relationship:

[0013]

[0014] where S p is the total surface area of the prefabricated slab, S i is the surface area of a single corrugated cavity, and n is the number of corrugated rings.

[0015] Optionally, in step S3, when the slab moves towards the second mold cavity under the action of the cryogenic fluid pressure until it is film-attached to the second mold cavity, the feeding amount of the flange area of the slab satisfies the following relationship:

[0016]

[0017] where L is the feeding length of the flange area, R is the radius of the slab, r is the radius of the slab after feeding in the flange area, and d is the diameter of the first mold cavity.

[0018] The advantages of the ultra-low temperature deformation control method for ultra-thin deep cavity curved aluminum alloy parts of the present invention compared with the prior art are as follows:

[0019] In the present invention, by filling cryogenic media into the first mold cavity of the shaping mold and the second mold cavity of the prefabricated mold to cool the first mold cavity and the second mold cavity, and simultaneously soaking and cooling the slab from both the front and back sides, the problems of low efficiency of the existing spray cooling method and uneven temperature distribution due to heat absorption by the mold are overcome. In addition, in the present invention, the prefabricated slab is unfolded in the cryogenic medium to obtain an ultra-thin deep cavity complex curved surface component with the same thickness as the original thin slab. The slab has good cooling effect, uniform temperature distribution, the specimen has the same thickness as the original slab, which not only inhibits the wrinkling of the thin slab, but also reduces the local cracking of the slab, and significantly increases the material hardening rate through a large pre-strain, and a component with uniform wall thickness distribution can be obtained under the cryogenic fluid pressure.

[0020] To solve the above problems, the present invention provides a device for regulating ultra-low temperature deformation of an aluminum alloy ultra-thin deep cavity curved part, which is used to implement the method for regulating ultra-low temperature deformation of the aluminum alloy ultra-thin deep cavity curved part. The forming device includes a feeding measurement structure, a pressurizing structure, a prefabrication mold, a shaping mold, and a conveying and storage structure. The slab is arranged between the prefabrication mold and the shaping mold, and the feeding measurement structure is connected to the flange area of the slab. The conveying and storage structure and the pressurizing structure are respectively connected to the prefabrication mold and the shaping mold in sequence, and the conveying and storage structure is used to provide ultra-low temperature medium to the prefabrication mold and the shaping mold through the pressurizing structure.

[0021] Optionally, the feeding measurement structure includes a data acquisition box and a displacement sensor connected electrically. The displacement sensor is connected to the flange area of the slab to measure the feeding amount of the flange area of the slab.

[0022] Optionally, the pressurizing structure includes: an oil cylinder and a piston rod. The oil cylinder is connected to the prefabrication mold and the shaping mold, and the piston rod is movably connected to the oil cylinder to compress the ultra-low temperature medium.

[0023] Optionally, the conveying and storage structure includes a self-pressurizing Dewar storage bottle and a liquid passing component that are connected to each other. The liquid passing component is connected to the oil cylinder.

[0024] Optionally, the surface shape of the prefabrication mold close to the shaping mold is corrugated, and the surface shape of the shaping mold close to the prefabrication mold is arc-shaped.

[0025] Compared with the prior art, the device for regulating ultra-low temperature deformation of the aluminum alloy ultra-thin deep cavity curved part of the present invention has a simple structure, and the device for regulating ultra-low temperature deformation of the aluminum alloy ultra-thin deep cavity curved part of the present invention and the method for regulating ultra-low temperature deformation of the aluminum alloy ultra-thin deep cavity curved part have the same advantages as those of the prior art, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flowchart of the method for regulating ultra-low temperature deformation of the aluminum alloy ultra-thin deep cavity curved part in the embodiment of the present invention;

[0027] Figure 2 It is a schematic diagram of the change curve of the total surface area of the prefabricated slab with the first mold cavity diameter and the number of corrugated rings in the embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of the change curve of the feeding amount of the flange area of the slab with the first mold cavity diameter and the number of corrugated rings in the embodiment of the present invention;

[0029] Figure 4Schematic diagram of the structure of the ultra-low temperature deformation control device for aluminum alloy ultra-thin deep cavity curved parts in the embodiments of the present invention;

[0030] Figure 5 Schematic diagram of the structural state of the ultra-low temperature deformation control device for aluminum alloy ultra-thin deep cavity curved parts when the slab is in the immersion cooling stage in the embodiments of the present invention;

[0031] Figure 6 Schematic diagram of the structural state of the ultra-low temperature deformation control device for aluminum alloy ultra-thin deep cavity curved parts when the slab is in the prefabrication stage in the embodiments of the present invention;

[0032] Figure 7 Schematic diagram of the structural state of the ultra-low temperature deformation control device for aluminum alloy ultra-thin deep cavity curved parts when the slab is in the flattening stage in the embodiments of the present invention;

[0033] Figure 8 Schematic diagram of the structural state of the ultra-low temperature deformation control device for aluminum alloy ultra-thin deep cavity curved parts when the slab is in the die-attached shaping stage in the embodiments of the present invention;

[0034] Figure 9 Schematic diagram of the structure of the prefabricated slab in the embodiments of the present invention;

[0035] Figure 10 Schematic diagram of the structure of the aluminum alloy ultra-thin deep cavity curved parts in the embodiments of the present invention.

[0036] Explanation of reference numerals:

[0037] 1 - Data acquisition box, 2 - Displacement sensor, 3 - Blank holder, 4 - Second oil cylinder, 5 - Second piston rod, 6 - Second die cavity, 7 - Prefabrication die, 8 - Check valve, 9 - Boost valve, 10 - Liquid passing valve, 11 - Self-pressurizing Dewar storage bottle, 12 - Shaping die, 13 - First die cavity, 14 - First oil cylinder, 15 - First piston rod, 16 - Ultra-low temperature medium, 17 - Slab. Detailed implementation manners

[0038] The technical solutions in the embodiments of the present application will be clearly and elaborately described below with reference to the accompanying drawings.

[0039] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features.

[0040] In the description of the embodiments of the present application, the description of the term "some embodiments" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expression of the above terms does not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0041] It should also be noted that in the drawings, the Z-axis represents the vertical direction, that is, the up and down position, and the positive direction of the Z-axis (that is, the direction pointed by the arrow of the Z-axis) represents up, and the negative direction of the Z-axis (that is, the direction opposite to the positive direction of the Z-axis) represents down; the X-axis in the drawings represents the horizontal direction, that is, the left and right position, and the positive direction of the X-axis (that is, the direction pointed by the arrow of the X-axis) represents left, and the negative direction of the X-axis (that is, the direction opposite to the positive direction of the X-axis) represents right; at the same time, it should be noted that the above-mentioned meanings of the Z-axis and the X-axis 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 cannot be understood as a limitation of the present invention.

[0042] As Figure 1 shown, the embodiments of the present invention provide a method for controlling the ultra-low temperature deformation of an aluminum alloy ultra-thin deep cavity curved surface part. Based on an ultra-low temperature forming die, the die includes a blank holder 3, a prefabrication die 7 and a sizing die 12, and the blank holder 3 and the prefabrication die 7 are arranged on the upper part of the sizing die 12. The method for controlling the ultra-low temperature deformation of the aluminum alloy ultra-thin deep cavity curved surface part includes the following steps:

[0043] Step S1, position the slab 17 on the upper surface of the sizing die 12, and the blank holder 3 and the prefabrication die 7 press downwards and clamp the slab 17.

[0044] Step S2, respectively fill the ultra-low temperature medium 16 into the first cavity 13 of the sizing die 12 and the second cavity 6 of the prefabrication die 7 to cool the first cavity 13, the second cavity 6 and the slab 17. By filling the ultra-low temperature medium 16 into the first cavity 13 of the sizing die 12 and the second cavity 6 of the prefabrication die 7 to cool the first cavity 13 and the second cavity 6, and simultaneously soak and cool the slab 17 from the front and back sides to overcome the problems of low efficiency of the existing spray cooling method and uneven temperature distribution due to the heat absorption of the die.

[0045] Step S3, compress the ultra-low temperature medium 16 in the first cavity 13 to apply an ultra-low temperature fluid pressure to the slab 17 in the reverse direction. The slab 17 moves towards the direction close to the second cavity 6 under the action of the ultra-low temperature fluid pressure and adheres to the second cavity 6 to obtain a prefabricated slab.

[0046] Step S4: Increase the load of the blank holder 3 to compress the cryogenic medium 16 in the second cavity 6 to apply a cryogenic fluid pressure to the blank 17 in the forward direction. The preformed blank moves towards the first cavity 13 under the action of the cryogenic fluid pressure until it is laminated, and the pressure is maintained for a preset time.

[0047] Step S5: Stop filling the cryogenic medium 16, retract the preformed mold 7 and the blank holder 3, relieve the pressure, and take out the ultra-thin deep-cavity curved aluminum alloy part.

[0048] In this embodiment, the preformed blank is unfolded in the cryogenic medium 16 to obtain an ultra-thin deep-cavity complex curved surface component with the same thickness as the original thin blank 17. The blank 17 has good cooling effect, uniform temperature distribution, and the specimen has the same thickness as the original blank 17, which not only inhibits the wrinkling of the thin plate but also reduces the local cracking of the blank 17, and significantly increases the material hardening rate through a large pre-strain, enabling the component with uniform wall thickness distribution to be obtained under the cryogenic fluid pressure.

[0049] In some preferred embodiments, the cryogenic medium 16 includes liquid oxygen (-183 °C), liquid argon (-186 °C), or liquid nitrogen (-196 °C), which are easily available raw materials, and the ultra-low temperature critical transformation temperature of the blank 17 is obtained through low-cost and high-efficiency double-sided immersion cooling.

[0050] In some preferred embodiments, the shape of the preformed blank is corrugated. Compared with the preformed blanks of other shapes (triangle, rectangle, and trapezoid), the corrugated preformed blank has a strong storage capacity for the blank, and its surface area can be controllably adjusted according to the number of corrugation turns and height, making it easy to control.

[0051] In this embodiment, the total surface area of the preformed blank satisfies the following relationship:

[0052]

[0053] where S p is the total surface area of the preformed blank, S i is the surface area of a single corrugated cavity, and n is the number of corrugation rings.

[0054] In this embodiment, in step S3, when the blank 17 moves towards the second cavity 6 under the action of the cryogenic fluid pressure until it is laminated with the second cavity 6, the feeding amount of the flange area of the blank 17 satisfies the following relationship:

[0055]

[0056] where L is the feeding length of the flange area, R is the radius of the blank, r is the radius of the blank after feeding in the flange area, and d is the diameter of the first cavity.

[0057] Such as Figure 4As shown in the figure, another embodiment of the present invention provides a device for regulating ultra-low temperature deformation of an ultra-thin deep cavity curved aluminum alloy part, which includes a feeding measurement structure, a pressurizing structure, a prefabricated mold 7, a shaping mold 12, and a conveying and storage structure. The slab 17 is arranged between the prefabricated mold 7 and the shaping mold 12, and the feeding measurement structure is connected to the flange area of the slab 17. The conveying and storage structure and the pressurizing structure are respectively connected to the prefabricated mold 7 and the shaping mold 12 in sequence, and the conveying and storage structure is used to provide ultra-low temperature medium 16 to the prefabricated mold 7 and the shaping mold 12 through the pressurizing structure.

[0058] In some embodiments, the device for regulating ultra-low temperature deformation of an ultra-thin deep cavity curved aluminum alloy part further includes a blank holder 3. The blank holder 3 is arranged above the shaping mold 12, and the side wall of the blank holder 3 is connected to the prefabricated mold 7. Thus, it is used to clamp the flange area of the slab 17, and the structure is simple.

[0059] In some embodiments, the feeding measurement structure includes a data acquisition box 1 and a displacement sensor 2 which are electrically connected. The displacement sensor 2 is connected to the flange area of the slab 17 to measure the feeding amount of the flange area of the slab 17.

[0060] In a preferred embodiment, the pressurizing structure includes: an oil cylinder and a piston rod. The oil cylinder is connected to the prefabricated mold 7 and the shaping mold 12, and the piston rod is movably connected to the oil cylinder to compress the ultra-low temperature medium 16.

[0061] Specifically, the pressurizing structure includes a first pressurizing structure and a second pressurizing structure. The first pressurizing structure is connected to the shaping mold 12, and the second pressurizing structure is connected to the prefabricated mold 7. The oil cylinder includes a first oil cylinder 14 and a second oil cylinder 4. The first oil cylinder 14 is arranged below the shaping mold 12 and connected to the shaping mold 12, and the second oil cylinder 4 is arranged above the prefabricated mold 7 and connected to the prefabricated mold 7. The piston rod includes a first piston rod 15 and a second piston rod 5. The first piston rod 15 cooperates with the first oil cylinder 14, and the second piston rod 5 cooperates with the second oil cylinder 4.

[0062] The conveying and storage structure, the first pressurizing structure and the shaping mold 12 are connected in sequence to form a first connection path; the conveying and storage structure, the second pressurizing structure and the prefabricated mold 7 are connected in sequence to form a second connection path. Thus, the conveying and storage structure conveys the ultra-low temperature medium 16 to the shaping mold 12 and the prefabricated mold 7 respectively through the first connection path and the second connection path.

[0063] In some embodiments, the conveying and storage structure includes a self-pressurizing Dewar storage bottle 11 and a liquid passage component which are interconnected. The liquid passage component is connected to the oil cylinder.

[0064] Specifically, a liquid passing valve 10 is provided on the self-pressurizing Dewar storage bottle 11. The liquid passing assembly includes a first liquid passing pipeline communicating with the first pressurizing structure and a second liquid passing pipeline communicating with the second pressurizing structure, and one-way valves 8 and pressurizing valves 9 are provided on both the first liquid passing pipeline and the second liquid passing pipeline. Thus, the transportation of the cryogenic medium 16 in the self-pressurizing Dewar storage bottle 11 to the prefabrication mold 7 and the shaping mold 12 is controlled.

[0065] In a preferred embodiment, the surface shape of the prefabrication mold 7 close to the shaping mold 12 is corrugated, and the surface shape of the shaping mold 12 close to the prefabrication mold 7 is arc-shaped.

[0066] In this embodiment, the working process of the cryogenic deformation control device for the ultra-thin deep cavity curved aluminum alloy part is as follows:

[0067] The blank holder 3, the prefabrication mold 7, and the shaping mold 12 are fixed on the workbench surface of the press, and are centered and positioned;

[0068] Pretreatment of the slab 17. After cleaning and grinding the surface of the circular thin slab, it is placed on the upper part of the shaping mold 12 to center the circular slab with the first cavity 13;

[0069] The blank holder 3 and the prefabrication mold 7 move downward to press the circular thin slab, and two closed cavities are respectively formed on the upper and lower surfaces of the thin slab to store the cryogenic cooling medium;

[0070] Use the transportation and storage structure to fill the cryogenic cooling medium in the shaping mold 12 to make it fill the entire first cavity 13 and cool the first cavity 13;

[0071] Use the transportation and storage structure to fill the cryogenic cooling medium in the prefabrication mold 7 to make it fill the entire second cavity 6 and cool the second cavity 6;

[0072] Use the cryogenic cooling medium filled in the first cavity 13 and the second cavity 6 to simultaneously soak and cool the front and back surfaces of the thin slab to obtain a lower forming temperature of the thin slab, and keep its temperature below the cryogenic critical transition temperature;

[0073] Use the first piston rod 15 in the first oil cylinder 14 to reversely compress the cryogenic cooling medium in the first cavity 13, and the cryogenic cooling medium is compressed and reversely applies a cryogenic fluid pressure to the cryogenic thin slab 17;

[0074] Under the action of a small blank holder load, the thin slab flows into the prefabrication mold 7 under the action of the cryogenic cooling medium pressure to prefabricate a corrugated slab;

[0075] When the flange feeding amount of the thin slab is equal to the feeding amount required for the final forming of the thin slab to be completely in contact with the mold, increase the blank holder load to ensure that no material enters the flange area when the prefabricated corrugated slab is flattened, and obtain a prefabricated slab;

[0076] The second piston rod 5 in the second oil cylinder 4 is used to compress the cryogenic cooling medium in the forward direction to increase the pressure, so that the preformed corrugated sheet blank is flattened under the action of the cryogenic fluid pressure.

[0077] The second oil cylinder 4 continues to increase the pressure of the cryogenic cooling medium in the forward direction, so that the expandable forming part is flattened under the action of the cryogenic fluid pressure and closely adheres to the first die cavity 13.

[0078] After the component forming and mold adhering are completed, the first die cavity 13 is pressurized by the cryogenic fluid pressure and kept under pressure.

[0079] The supply of the cryogenic cooling medium is stopped, the second oil cylinder 4 returns, the pressurized cryogenic cooling medium is unloaded, and the workpiece is taken out.

[0080] The synchronous pressurizing structure is unloaded, and the prefabricated mold 7 and the blank holder 3 move upward and then return.

[0081] After the forming is completed, the pressure is released and the workpiece is taken out, and the test piece is taken out from the first die cavity 13 of the sizing die 12 to obtain an ultra-thin deep cavity curved surface part made of aluminum alloy.

[0082] In this embodiment, the first oil cylinder 14 is used to compress the cryogenic medium 16 in the reverse direction to apply a cryogenic hydraulic load to the sheet blank 17 for prefabricating the corrugations of the blank to store more sheet materials; the flange area of the sheet blank 17 is fixed by the blank holder 3, and the first oil cylinder is used to compress the cryogenic medium 16 in the forward direction to apply a cryogenic hydraulic load to the sheet blank 17, so that the corrugated blank is expanded due to bulging in the cryogenic environment and gradually adheres to the inner surface of the female die. Thus, by expanding the prefabricated sheet blank in the cryogenic medium 16, an ultra-thin deep cavity complex curved surface component with the same thickness as the original thin sheet blank 17 is obtained. The sheet blank 17 has good cooling effect, uniform temperature distribution, the test piece has the same thickness as the original sheet blank, which not only inhibits the wrinkling of the thin sheet, but also reduces the local cracking of the sheet blank 17, and significantly increases the material hardening rate through a large pre-strain, and a component with uniform wall thickness distribution can be obtained under the cryogenic fluid pressure.

[0083] Embodiment 1

[0084] This embodiment provides a method for controlling the cryogenic deformation of an ultra-thin deep cavity curved surface part made of aluminum alloy. Specifically, taking AA2219 aluminum alloy with a thickness of 4 mm as an example, a forming method for a 3350 mm large-size head at -196 °C in liquid nitrogen is provided, including the immersion cooling stage of the sheet blank 17, the corrugation prefabrication stage, the flattening stage of the prefabricated corrugations, and the mold adhering and sizing stage of the sheet blank 17, as Figures 5 - 8 shown, and specifically includes the following steps:

[0085] The blank holder 3, the prefabricated mold 7, and the sizing die 12 are fixed on the workbench surface of the press and centered and positioned.

[0086] Pretreatment of the slab 17. After cleaning and grinding the surface of the circular thin slab with a diameter of 4.2 m, it is placed on the upper part of the shaping die 12 to align the circular slab with the first cavity 13;

[0087] The blank holder 3 and the prefabrication die 7 move downward to press the circular thin slab, forming two closed cavities on the upper and lower surfaces of the thin slab respectively for storing liquid nitrogen;

[0088] Use the conveying and storage structure to fill liquid nitrogen in the shaping die 12 to make it fill the entire first cavity 13 and cool the first cavity 13;

[0089] Use the conveying and storage structure to fill liquid nitrogen in the prefabrication die 7 to make it fill the entire second cavity 6 and cool the second cavity 6;

[0090] Use the liquid nitrogen filled in the first cavity 13 and the second cavity 6 to soak and cool the front and back surfaces of the thin slab simultaneously for 15 min to make its temperature reach -196 °C;

[0091] Use the first piston rod 15 in the first oil cylinder 14 to compress the liquid nitrogen in the first cavity 13. The liquid nitrogen is compressed and applies a cryogenic fluid pressure to the cryogenic slab in the reverse direction;

[0092] Under the action of a small blank holder load of 3 - 5 MPa, the thin slab flows into the prefabrication die 7 under the action of the liquid nitrogen pressure to prefabricate a corrugated slab;

[0093] When the flange feed amount of the thin slab is equal to the feed amount required for the final forming of the thin slab to be completely in contact with the die, increase the blank holder load to 6 - 10 MPa to ensure that no material enters the flange area when the prefabricated corrugated slab is flattened, and obtain a prefabricated slab, as Figure 9 shown;

[0094] Use the second piston rod 5 in the second oil cylinder 4 to compress the liquid nitrogen in the forward direction to increase the pressure, so that the prefabricated corrugated slab is flattened under the action of the cryogenic fluid pressure;

[0095] The second oil cylinder 4 continues to increase the pressure of the liquid nitrogen in the forward direction, so that the expansion forming part is flattened under the action of the cryogenic fluid pressure and closely contacts the first cavity 13;

[0096] After the component forming and die contact are completed, use the cryogenic fluid pressure to increase the pressure of the first cavity 13 and hold the pressure for 5 min;

[0097] The supply of liquid nitrogen stops, the second oil cylinder 4 returns, the pressure-increasing liquid nitrogen is unloaded, and the part is taken out;

[0098] The synchronous pressure-increasing structure is unloaded, and the prefabrication die 7 and the blank holder 3 move upward and return;

[0099] After the forming is completed, the pressure is released and the part is taken out. The test piece is taken out from the first cavity 13 of the shaping die 12 to obtain an ultra-thin deep cavity curved surface part of aluminum alloy, asFigure 10 as shown

[0100] It should be noted that in this embodiment, the accurate calculation of the surface area of the prefabricated slab blank is the key to controlling the required blank amount for the forward bulging expansion of the prefabricated slab blank, and the calculation of the surface area of the prefabricated slab blank is related to the shape, area of a single corrugated cavity, and the number of corrugation rings. Since triangular, rectangular, and trapezoidal prefabricated parts have obvious sharp corners, it is easy to cause large stress concentration and cracking in ultra-thin components. Therefore, based on the total surface area calculation formula of the prefabricated slab blank, assuming that the corrugation shape of the prefabricated slab blank is a semi-circular ring, the calculation formula for the total surface area of the prefabricated slab blank is as follows:

[0101]

[0102] where S p is the total surface area of the prefabricated slab blank, d is the diameter of the first die cavity, and n is the number of corrugation rings.

[0103] According to the above calculation formula, the variation relationship of the calculated surface area S p with the diameter d of the first die cavity and the number n of corrugation rings is as Figure 2 shown. It can be seen from Figure 2 that when the number of corrugation rings is constant, the total surface area of the prefabricated slab blank is positively correlated with the diameter of the first die cavity; when the diameter of the first die cavity is constant, the total surface area of the prefabricated slab blank is positively correlated with the number of corrugation rings. Therefore, in the process of reverse bulging of prefabricated corrugations, for ultra-thin curved surface components with a relatively large diameter, the method of increasing the number of corrugation rings is adopted to increase the storage capacity.

[0104] It should also be noted that in this embodiment, the feeding amount of the flange area of the slab blank 17 is the key to the die-fitting control of the bulging expansion of the slab blank 17. Assuming that the corrugation shape of the prefabricated slab blank is a semi-circular ring, according to the above total surface area calculation formula of the prefabricated slab blank, the variation curve of the feeding amount of the flange area of the slab blank with the diameter of the first die cavity and the number of corrugation rings is as Figure 3 shown. It can be seen from Figure 3 that when the number of corrugation rings is constant, the feeding amount of the flange area of the slab blank 17 is positively correlated with the diameter of the first die cavity; when the diameter of the first die cavity is constant, the feeding amount of the flange area is negatively correlated with the number of corrugation rings. Therefore, in the process of reverse bulging of prefabricated corrugations, for ultra-thin curved surface components with a relatively large diameter and a specific surface area, by increasing the number of corrugation rings, the feeding amount of the flange area can be reduced, thereby reducing the corrugation height and preventing the component from cracking prematurely.

[0105] Therefore, the ultra-low temperature deformation control method for the ultra-thin deep cavity curved aluminum alloy parts provided by this embodiment can simultaneously perform immersion cooling on both the front and back sides of the slab 17. The cooling effect of the slab 17 is good, the temperature distribution is uniform, the specimen has the same thickness as the original slab, which not only inhibits the wrinkling of the thin plate but also reduces the local cracking of the slab 17, and significantly increases the material hardening rate through a large pre-strain, and can improve the wall thickness distribution uniformity of the component under the ultra-low temperature fluid pressure.

[0106] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A method for controlling ultra-low temperature deformation of an ultra-thin and deep cavity curved aluminum alloy part, characterized in that, Based on a cryogenic forming die, the die includes a blank holder (3), a prefabrication die (7) and a sizing die (12), and the blank holder (3) and the prefabrication die (7) are arranged above the sizing die (12). The cryogenic deformation control method for an ultra-thin and deep-cavity curved aluminum alloy part includes the following steps: Step S1, position the slab (17) on the upper surface of the sizing die (12), and the blank holder (3) and the prefabrication die (7) press downwards and clamp the slab (17); Step S2, fill cryogenic medium (16) into the first cavity (13) of the sizing die (12) and the second cavity (6) of the prefabrication die (7) respectively to cool the first cavity (13), the second cavity (6) and the slab (17); Step S3, compress the cryogenic medium (16) in the first cavity (13) to reversely apply a cryogenic fluid pressure to the slab (17). Under the action of the cryogenic fluid pressure, the slab (17) moves towards the direction close to the second cavity (6) until it adheres to the second cavity (6). At this time, control the flange area of the slab (17) to stop feeding, and obtain a corrugated prefabricated slab; Step S4, increase the load of the blank holder (3), compress the cryogenic medium (16) in the second cavity (6) to positively apply a cryogenic fluid pressure to the slab (17). Under the action of the cryogenic fluid pressure, the prefabricated slab moves towards the direction close to the first cavity (13) until it adheres, and hold the pressure for a preset time; Step S5, stop filling the cryogenic medium (16), the prefabrication die (7) and the blank holder (3) return, relieve the pressure, and take out an ultra-thin and deep-cavity curved aluminum alloy part with the same thickness as the slab (17); In step S3, the feeding amount of the flange area of the slab (17) satisfies the following relational expression: Among them, L is the feeding length of the flange area, R is the radius of the slab, r is the radius of the slab after feeding in the flange area, d is the diameter of the first cavity, S p is the total surface area of the prefabricated slab, S i is the surface area of a single corrugated cavity, and n is the number of corrugated rings.

2. The method for regulating and controlling ultra-low temperature deformation of an aluminum alloy ultra-thin deep cavity curved surface part according to claim 1, wherein The cryogenic medium (16) includes liquid oxygen, liquid argon or liquid nitrogen.

3. A device for controlling ultra-low temperature deformation of an ultra-thin deep cavity curved aluminum alloy part, which is used to implement the method for controlling ultra-low temperature deformation of an ultra-thin deep cavity curved aluminum alloy part as described in any one of claims 1-2, characterized in that It includes a feeding measurement structure, a pressurization structure, a prefabrication die (7), a sizing die (12) and a conveying and storage structure. The slab (17) is used to be arranged between the prefabrication die (7) and the sizing die (12), and the feeding measurement structure is connected to the flange area of the slab (17). The conveying and storage structure and the pressurization structure are respectively connected to the prefabrication die (7) and the sizing die (12) in sequence, and the conveying and storage structure is used to provide the cryogenic medium (16) to the prefabrication die (7) and the sizing die (12) through the pressurization structure.

4. The ultra-low temperature deformation control device for the ultra-thin and deep cavity curved aluminum alloy part according to claim 3, characterized in that, The feeding measurement structure includes a data acquisition box (1) and a displacement sensor (2) which are electrically connected. The displacement sensor (2) is connected to the flange area of the slab (17) to measure the feeding amount of the flange area of the slab (17).

5. The ultra-low temperature deformation control device for the ultra-thin and deep cavity curved aluminum alloy part according to claim 3, characterized in that, The pressurization structure includes: an oil cylinder and a piston rod. The oil cylinder is connected to the prefabrication die (7) and the sizing die (12), and the piston rod is movably connected to the oil cylinder to compress the cryogenic medium (16).

6. The ultra-low temperature deformation regulation device for the ultra-thin deep cavity curved aluminum alloy part according to claim 5, wherein, The conveying and storage structure includes a self-pressurizing Dewar storage bottle (11) and a liquid passage component that are connected to each other, and the liquid passage component is connected to the oil cylinder.

7. The ultra-low temperature deformation control device for the ultra-thin and deep cavity curved aluminum alloy part according to claim 5, characterized in that, The surface of the prefabricated mold (7) close to the shaping mold (12) has a corrugated shape, and the surface of the shaping mold (12) close to the prefabricated mold (7) has an arc shape.

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