Hydraulic forming device and forming method for curved-surface cylindrical part

Abstract

The invention discloses a curved-surface cylindrical part hydraulic forming device and method, and relates to the technical field of cylindrical part forming, the curved-surface cylindrical part hydraulic forming device comprises a die and a pressurization system, and the die comprises a male die and a female die; the female die is annular, at least part of the male die can be arranged in the female die, an annular gap between the male die and the female die is used for containing a barrel blank, a forming curved surface is constructed outside the male die or in the female die, and under the state that the barrel blank is placed, a closed inner cavity is formed between the male die and the barrel blank, and a closed outer cavity is formed between the female die and the barrel blank. The forming curved surface is a cavity wall of the inner cavity or the outer cavity; fluid channels communicated with the inner cavity or the outer cavity are formed in the male die and the female die; the pressurization system is used for filling pressure fluid into the inner cavity and the outer cavity and controlling the pressure difference between the outer cavity and the inner cavity, the invention further provides a curved-surface cylindrical part hydraulic forming device and method, and the forming size precision of the multi-layer rotary cylindrical part with the curved generatrix characteristic can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of cylindrical component forming, and in particular to a hydraulic forming device and a forming method for a curved cylindrical component. Background Art

[0002] Large-sized multi-layer curved cylindrical parts are widely used in aerospace, automobile manufacturing, shipbuilding and other fields. Due to their unique structural characteristics, they are usually used as nozzles for fluid flow pipelines. The service environment of nozzles is mostly high temperature and high pressure, which requires multi-layer curved cylindrical parts to have relatively stable mechanical properties and dimensional accuracy. In traditional manufacturing processes, stamping-welding and spinning forming technologies are usually used to manufacture such large-sized multi-layer curved cylindrical parts.

[0003] The stamping-welding manufacturing process requires processing metal sheets into multiple curved plate blanks, which are then precisely welded along the generatrix to form the desired tapered structure. However, this process has significant limitations. On the one hand, the curved plate blanks are prone to springback during the stamping process, which makes it difficult to accurately control the surface accuracy after forming, increasing the difficulty and cost of subsequent processing. On the other hand, since the component is welded from multiple plates, welding deformation is inevitable during the welding process. This deformation will directly affect the surface dimensional accuracy of the component, and then affect its overall performance. Therefore, after the stamping-welding process is completed, it usually takes a lot of time and cost to correct the surface of the component.

[0004] In order to overcome the shortcomings of the stamping-welding process, the spin forming process was proposed and applied to the manufacture of multi-layer rotating cylindrical parts with curved generatrix characteristics. The spin forming process gradually fits the metal sheet to the mold surface through continuous rotation and local plastic deformation, thereby forming the required rotating cylindrical part structure. Although this process effectively reduces the number of welds and reduces the risk of welding deformation, it also has challenges. Spin forming requires multiple steps, and each layer of rotating cylindrical parts needs to be formed separately, so that the fitting accuracy between the inner and outer layers is low, affecting the service strength and stability of the multi-layer rotating cylindrical parts.

[0005] In addition, considering the use requirements of multi-layer rotating cylindrical parts with curved generatrix characteristics in extreme environments such as high temperature and high pressure, the material selection usually tends to be high-strength and high-temperature-resistant metals, such as stainless steel and high-temperature alloys. Under the condition of large diameter-to-thickness ratio constraints, the residual stress and elastic deformation generated by such materials after deformation unloading are both difficult problems that affect the forming accuracy of multi-layer rotating cylindrical parts.

[0006] In summary, the existing manufacturing technologies of multi-layer rotating cylindrical parts with curved generatrix features have certain limitations and cannot meet the growing demand for high-performance and high-precision manufacturing. Therefore, it is necessary to explore more advanced and efficient manufacturing processes to improve the forming dimensional accuracy of multi-layer rotating cylindrical parts with curved generatrix features. Summary of the invention

[0007] The purpose of the present invention is to provide a hydraulic forming device and forming method for curved cylindrical parts, so as to solve the problems existing in the above-mentioned prior art and improve the forming dimensional accuracy of multi-layer rotating cylindrical parts with curved generatrix characteristics.

[0008] To achieve the above object, the present invention provides the following solutions: The present invention provides a hydraulic forming device for a curved cylindrical part, comprising: a mold and a boosting system, wherein the mold comprises a punch and a die; the punch and the die; the die is annular, and at least a portion of the punch can be arranged in the die; the annular gap between the punch and the die is used to place a cylindrical blank; a forming curved surface is constructed on the outside of the punch or inside the die; when the cylindrical blank is placed, a closed inner cavity is formed between the punch and the cylindrical blank, and a closed outer cavity is formed between the die and the cylindrical blank; the forming curved surface is a cavity wall of the inner cavity or the outer cavity; a fluid channel connecting the inner cavity or the outer cavity is constructed on both the punch and the die; the boosting system is used to fill the inner cavity and the outer cavity with pressurized fluid and control the pressure difference between the outer cavity and the inner cavity.

[0009] Compared with the existing forming methods, the multi-layer rotary cylindrical parts with curved generatrix characteristics manufactured by the above-mentioned curved cylindrical parts hydraulic forming device have a wider range. In addition, after the component is formed, the springback is small, the contour accuracy of the forming surface is high, and when forming multi-layer components, the interlayer fit is high, and there is no excessive requirement for mold manufacturing accuracy, which can effectively reduce manufacturing costs and improve economic benefits and productivity.

[0010] Preferably, the upper and lower parts of the outer wall of the male mold and the inner wall of the female mold form sealing sections, and the male mold and the female mold of the sealing section press the upper and lower parts of the tube blank to achieve sealing of the inner cavity and the outer cavity.

[0011] Preferably, the male mold and / or the female mold are an integral structure.

[0012] Preferably, the male mold and / or the female mold is a separate structure to facilitate removing the formed component from the mold.

[0013] Preferably, the punch is annular, and the two end openings of the fluid channel on the punch are respectively opened on the inner wall and outer wall of the punch; the two end openings of the fluid channel on the die are respectively opened on the inner wall and outer wall of the die.

[0014] The present invention also provides a method for hydraulically forming a curved cylindrical part, comprising: forming a cylindrical blank using the curved cylindrical part hydraulic forming device as described above.

[0015] The details are as follows: Step 1: Prepare the required single-layer or multi-layer tube blank according to the number of layers required; Step 2: placing the tube blank in the concave die, and closing the molds to form a closed inner cavity between the male die and the tube blank, and a closed outer cavity between the concave die and the tube blank; Step 3: injecting a high-pressure fluid of a preset loading path into the inner cavity and the outer cavity using a booster system; Step 4: Under the real-time cooperation of the fluid pressure in the inner cavity and the outer cavity, the tube blank undergoes plastic deformation until it completely abuts against the forming curved surface, thus obtaining a formed component with a curved generatrix feature; Step 5: After the forming is completed, the pressure fluid in the inner cavity and the outer cavity is removed and the formed component is taken out.

[0016] Compared with the existing forming methods, the multi-layer rotary cylindrical parts with curved generatrix characteristics manufactured by the above-mentioned curved cylindrical parts hydraulic forming method have a wider range. In addition, after the component is formed, the springback is small, the contour accuracy of the forming surface is high, and when forming multi-layer components, the interlayer fit is high, and there is no excessive requirement for mold manufacturing accuracy, which can effectively reduce manufacturing costs and improve economic benefits and productivity.

[0017] Preferably, in step six, the excess of the formed component is cut off to obtain a final component.

[0018] Preferably, in step 4, the pressure difference between the inner cavity and the outer cavity is kept constant during the deformation of the tube blank.

[0019] Preferably, in the step 1, the required single-layer or multi-layer tube blank is prepared by coil welding or spinning.

[0020] Compared with the prior art, the present invention has achieved the following technical effects: 1. The multi-layer tube blank in the present invention is always in an internal and external bidirectional normal compressive stress field environment during the forming process. The normal compressive stress field from beginning to end can effectively suppress the relative sliding between the layers of the shell, thereby ensuring the dimensional accuracy and fit of the formed part.

[0021] 2. In the initial forming stage, the present invention simultaneously injects a fluid medium of a certain pressure into the inner cavity on one side and the outer cavity on the other side of the multi-layer tube blank. Driven by the internal and external pressure difference, the tube blank undergoes stable plastic deformation, wherein one of the inner and outer cavities is a back pressure cavity. The fluid in the back pressure cavity gives the tube blank a back pressure, which can effectively suppress the plastic buckling instability of the tube blank during the deformation process, thereby improving the yield rate of the manufacturing process of multi-layer rotating cylindrical parts.

[0022] 3. The hydraulic forming method of the present invention can be used to manufacture rotary cylindrical parts with different numbers of layers and different generatrix shapes, and the forming range is wider, specifically including: (1) Number of layers (n): single layer (n=1), double layer (n=2), multi-layer (n≥3); (2) Busbar shape (φ1 ≥ φ2): Unequal diameters at the top and bottom (φ1>φ2): external convex curved generatrix conical cylinder, internal concave curved generatrix conical cylinder; Equal diameters at upper and lower levels (φ1 = φ2): externally convex curved generatrix drum-shaped cylinder, internally concave curved generatrix drum-shaped cylinder.

[0023] In summary, compared with the existing forming methods, the multi-layer rotary cylindrical parts with curved generatrix characteristics manufactured by the solution provided by the present invention have a wider range. In addition, after the component is formed, the springback is small, the contour accuracy of the forming surface is high, and when forming multi-layer components, the interlayer fit is high, and there is no excessive requirement for mold manufacturing accuracy, which can effectively reduce manufacturing costs and improve economic benefits and productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a schematic diagram of the process of the hydraulic forming method of the curved cylindrical part in an embodiment of the present invention.

[0026] Figure 2 It is a schematic structural diagram of a hydraulic forming device for a curved cylindrical part in an embodiment of the present invention.

[0027] Figure 3 It is a schematic diagram of a rotating cylindrical part having a curved generatrix feature that can be formed in an embodiment of the present invention.

[0028] Figure 4 : a is a schematic diagram of the structure of a coiled welded fan-shaped slab; b is a schematic diagram of the structure of a coiled welded tube after coiling the coiled welded fan-shaped slab in a; c is a cross-sectional view of b; Figure 5 : a is a schematic diagram of the structure of a double-layer tube blank; b is a cross-sectional view of a; Figure 6 : a is a schematic diagram of the structure of a three-layer tube blank; b is a cross-sectional view of a; Figure 7 : a is a front view of a spun circular slab, b is a side view of a; c is a front view of a spun tube formed by spinning the spun circular slab in a, d is a three-dimensional view of c; Figure 8 : From left to right are schematic diagrams of the outer convex curved generatrix conical cylinder and the inner concave curved generatrix conical cylinder matching with the mold before plastic deformation; Fig. 9 : From left to right are schematic diagrams of the outer convex curved generatrix conical cylinder and the inner concave curved generatrix conical cylinder matching with the mold after plastic deformation; Fig.10 : From left to right are schematic diagrams of the inner concave curved generatrix drum-shaped cylinder and the outer convex curved generatrix drum-shaped cylinder matching with the mold before plastic deformation; Fig.11 : From left to right are schematic diagrams of the inner concave curved generatrix drum-shaped cylinder and the outer convex curved generatrix drum-shaped cylinder matching with the mold after plastic deformation; In the figure: 1-tube blank; 101-sector-shaped plate blank; 102-rolled welded tube blank; 104-double-layer tube blank; 106-three-layer tube blank; 108-round plate blank; 110-spun tube blank; 2-formed component; 201-convex curved busbar cone shell component; 202-concave curved busbar cone shell component; 203-concave curved busbar drum-shaped component; 204-convex curved busbar drum-shaped component; 205-double-layer curved busbar cone shell component; 206-double-layer curved busbar cone shell component section Figure; 207-three-layer curved busbar cone shell component; 208-cross-sectional view of three-layer curved busbar cone shell component; 3-die; 301-die fluid channel; 302-die upper die; 303-die lower die; 4-punch; 401-punch upper sealing section; 402-punch forming section; 403-punch lower sealing section; 404-punch fluid channel; 5-deformation chamber; 6-back pressure chamber; 7-die pressurization system; 8-punch pressurization system; 9-control system. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Combine the following Figures 1 to 11 , describing an embodiment of the present invention.

[0032] The present invention provides a hydraulic forming device for curved cylindrical parts, such as Figure 2 , Figure 8~Figure 11 As shown, it includes: a mold and a boosting system, the mold includes a punch 4 and a die 3; the punch 4 and the die 3; the die 3 is annular, at least part of the punch 4 can be arranged in the die 3, the annular gap between the punch 4 and the die 3 is used to place the tube blank 1, the outside of the punch 4 or the inside of the die 3 is configured with a forming curved surface, when the tube blank 1 is placed, a closed inner cavity is formed between the punch 4 and the tube blank 1, and a closed outer cavity is formed between the die 3 and the tube blank 1, and the forming curved surface is a cavity wall of the inner cavity or the outer cavity; the punch 4 and the die 3 are both configured with a fluid channel connecting the inner cavity or the outer cavity, one of the inner cavity and the outer cavity is a back pressure cavity 6, and the other is a forming cavity; the boosting system is used to fill the inner cavity and the outer cavity with pressure fluid and control the pressure difference between the outer cavity and the inner cavity.

[0033] When in use, pressurized fluid is filled into the inner cavity and the outer cavity through the fluid channel, and the pressure difference between the inner cavity and the outer cavity is controlled. Driven by the internal and external pressure difference, the tube blank 1 undergoes stable plastic deformation, and the back pressure can effectively suppress the plastic buckling and instability of the tube blank 1 during the deformation process, thereby improving the yield rate of the manufacturing process of multi-layer rotating cylindrical parts.

[0034] Compared with the existing forming methods, in the hydraulic forming mold for curved cylindrical parts provided by the present invention, the bidirectional fluid pressure forming can independently control the pressure difference inside and outside the cylinder blank 1 in real time, so that the cylinder blank 1 is always in a normal pressure stress field environment to undergo stable plastic deformation, avoiding excessive thinning or even cracking of the material due to the existence of the suspended area; the bidirectional pressure coordination can ensure that the component and the mold are completely fitted, especially when forming a multi-layer curved busbar cylinder blank 1, a tighter interlayer fit and more uniform deformation can be achieved; it can reduce common defects of traditional processes such as wrinkles and uneven thinning, optimize the stress state, reduce the amount of springback, and improve the shape accuracy; and the forming method of the present invention can manufacture multi-layer rotary cylindrical parts with concave or convex curved busbar features, and the manufacturing range is wider. In summary, compared with the existing forming methods, the hydraulic forming method provided by the present invention has a wider range of forming components 2, less springback occurs when forming components 2, and the contour accuracy of the forming surface is higher; and when forming multi-layer components, the interlayer fit is higher, there is no excessive requirement for the mold and control system 9, it can reduce the mold cost, and improve economic benefits and productivity.

[0035] In some embodiments, the upper and lower parts of the outer wall of the punch 4 and the inner wall of the die 3 form sealing sections, and the punch 4 and the die 3 of the sealing section press the upper and lower parts of the tube blank 1 to achieve sealing of the inner and outer cavities.

[0036] This embodiment achieves sealing of the inner cavity and the outer cavity.

[0037] like Figure 5 and Figure 7 As shown, when the tube blank 1 is placed in the mold and before the forming begins, the upper end of the tube blank 1 is sealed with the upper sealing section of the forming die 3 and the upper sealing section of the punch 4; the lower end of the tube blank 1 is sealed with the lower sealing section of the die 3 and the lower sealing section of the punch 4; the cavity between the tube blank 1 and the die 3 is the outer cavity; the cavity between the tube blank 1 and the punch 4 is the inner cavity. The inner cavity is the cavity between the punch 4 and the tube blank 1, where the fluid gradually increases during the deformation process, and the fluid pressure is the main driving force for the plastic deformation of the material, that is, it is called the deformation cavity 5; the outer cavity is the cavity between the forming die 3 and the tube blank 1, where the fluid gradually decreases during the deformation process, and the role of the fluid pressure is to act as a back pressure to inhibit the plastic buckling instability of the material, that is, it is called the back pressure cavity 6; during the forming process, the fluid pressure of the deformation cavity 5 and the fluid pressure of the back pressure cavity 6 increase simultaneously, and after reaching a certain pressure, the fluid pressure in the back pressure cavity 6 remains stable, and the fluid pressure in the deformation cavity 5 continues to increase until it reaches the forming pressure, and the deformation of the component is controlled by the pressure difference between the two.

[0038] like Figure 6 and Figure 8 As shown, when the tube blank 1 is placed in the mold and the forming is completed, the fluid pressure difference is used to cause the tube blank 1 to undergo plastic deformation in the mold, and gradually form a multi-layer rotary cylindrical part with a curved generatrix feature. During the forming process, the fluid pressure in the deformation chamber 5 is used to apply pressure to the tube blank 1, causing the tube blank 1 to undergo plastic deformation; the fluid pressure in the back pressure chamber 6 is used to assist the forming process, thereby suppressing the plastic buckling instability during the forming process of the tube blank 1; the wall thickness and shape accuracy are controlled by the combined action of the deformation chamber 5 and the back pressure chamber 6, so that when forming the multi-layer rotary tube blank 1 with a curved generatrix feature, the deformation zone is deformed at the same time, thereby improving the fit between the multi-layer rotary cylindrical parts with a curved generatrix feature.

[0039] The male die 4 and the female die 3 in the embodiment of the present invention have two forms, one is an integrated structure, and the other is an upper and lower separated structure.

[0040] Specifically, Figures 8 to 11 shown.

[0041] It can be understood that the split structure is set to facilitate the removal of the formed component. When the target shape of the component is an outward convex curved busbar drum-shaped cylinder, the die 3 needs to be set as an upper and lower split structure. When the target shape of the component is an inward concave curved busbar drum-shaped cylinder, the punch 4 needs to be set as an upper and lower split structure.

[0042] In some embodiments, the punch 4 is annular, and the two end openings of the fluid channel on the punch 4 are respectively opened on the inner wall and outer wall of the punch 4; the two end openings of the fluid channel on the die 3 are respectively opened on the inner wall and outer wall of the die 3.

[0043] like Figure 2 As shown, the hydraulic forming device for curved cylindrical parts includes, from top to bottom and from left to right, a punch 4, a die 3, a punch pressurizing system 8, a die pressurizing system 7 and a control system 9; the punch fluid channel 404 is connected to the punch pressurizing system 8, the die fluid channel 301 is connected to the die pressurizing system 7, the punch pressurizing system 8 and the die pressurizing system 7 are both connected to the control system 9, that is, the pressurizing system includes the punch pressurizing system 8 and the die pressurizing system 7.

[0044] The present invention also provides a method for hydraulically forming a curved cylindrical part, using the device for hydraulically forming a curved cylindrical part as described above, comprising: Step 1: Prepare the required single-layer or multi-layer tube blank 1 by coil welding or spinning according to the number of layers required; Step 2: Place the tube blank 1 in the concave die 3, and close the molds to form a closed inner cavity between the male die 4 and the tube blank 1, and a closed outer cavity between the concave die 3 and the tube blank 1; Step 3: Use the booster system to inject high-pressure fluid with a preset loading path into the inner cavity and the outer cavity; Step 4: Under the real-time cooperation of the fluid pressure in the inner cavity and the outer cavity, the tube blank 1 undergoes plastic deformation until it completely abuts against the forming curved surface, that is, a formed component 2 with a curved generatrix characteristic is obtained; during the deformation of the tube blank 1, the pressure difference between the inner cavity and the outer cavity is kept constant; Step 5: After the forming is completed, the pressure fluid in the inner cavity and the outer cavity is removed, and the formed component 2 is taken out; Step 6: Cut off the excess of the formed component 2 to obtain the final component.

[0045] Compared with the existing forming methods, in the hydraulic forming method of curved cylindrical parts provided by the present invention, the bidirectional fluid pressure forming independently controls the pressure difference inside and outside the cylinder blank 1 in real time so that the cylinder blank 1 is always in a normal pressure stress field environment to undergo stable plastic deformation, avoiding excessive thinning or even cracking of the material due to the existence of the suspended area; the bidirectional pressure coordination can ensure that the component and the mold are completely fitted, especially when forming a multi-layer curved busbar cylinder blank 1, a tighter interlayer fit and more uniform deformation can be achieved; it can reduce common defects of traditional processes such as wrinkles and uneven thinning, optimize the stress state, reduce the amount of springback, and improve the shape accuracy; and the forming method of the present invention can manufacture multi-layer rotary cylindrical parts with concave or convex curved busbar features, and the manufacturing range is wider. In summary, compared with the existing forming methods, the hydraulic forming method provided by the present invention has a wider range of forming components 2, less springback occurs when forming components 2, and the contour accuracy of the forming surface is higher; and when forming multi-layer components, the interlayer fit is higher, there is no excessive requirement for the mold and control system 9, it can reduce the mold cost, and improve economic benefits and productivity.

[0046] In the above step 1, the rolled welded tube blank 102 is formed by rolling the fan-shaped plate blank 101 into a conical tube and then welding it along the generatrix, and the welding method includes one or more of argon arc welding, laser welding and plasma arc welding; the spun tube blank 110 is spun by a circular plate blank 108. The existing forming technology is relatively mature for the manufacture of tube blanks, and will not be described in detail here.

[0047] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A device for hydraulically forming a curved cylindrical part, characterized in that: include: A mold and a pressurizing system, wherein the mold includes a male mold and a female mold; The die is annular, and at least part of the punch can be arranged in the die. The annular gap between the punch and the die is used to place the cylinder blank. The outside of the punch or the inside of the die is configured with a forming curved surface. When the cylinder blank is placed, a closed inner cavity is formed between the punch and the cylinder blank, and a closed outer cavity is formed between the die and the cylinder blank. The forming curved surface is a cavity wall of the inner cavity or the outer cavity. The punch and the die are both configured with a fluid channel connected to the inner cavity or the outer cavity. The boosting system is used to fill the inner cavity and the outer cavity with pressurized fluid and control the pressure difference between the outer cavity and the inner cavity.

2. The curved cylindrical component hydraulic forming device according to claim 1, characterized in that: The upper and lower parts of the outer wall of the male mold and the inner wall of the female mold form sealing sections, and the male mold and the female mold of the sealing section press the upper and lower parts of the tube blank to achieve sealing of the inner cavity and the outer cavity.

3. The curved cylindrical component hydraulic forming device according to claim 1, characterized in that: The male mold and / or the female mold are an integrated structure.

4. The curved cylindrical component hydraulic forming device according to claim 1, characterized in that: The male mold and / or the female mold are / is a split structure.

5. The curved cylindrical component hydraulic forming device according to claim 1, characterized in that: The punch is annular, and the two end openings of the fluid channel on the punch are respectively opened on the inner wall and outer wall of the punch; the two end openings of the fluid channel on the die are respectively opened on the inner wall and outer wall of the die.

6. A method for hydraulically forming a curved cylindrical part, characterized in that: The cylindrical blank is formed using the curved cylindrical component hydraulic forming device described in any one of claims 1 to 5.

7. The method for hydroforming a curved cylindrical part according to claim 6, characterized in that: include: Step 1: Prepare the required single-layer or multi-layer tube blank according to the number of layers required; Step 2: placing the tube blank in the concave die, and closing the molds to form a closed inner cavity between the male die and the tube blank, and a closed outer cavity between the concave die and the tube blank; Step 3: injecting a high-pressure fluid of a preset loading path into the inner cavity and the outer cavity using a booster system; Step 4: Under the real-time cooperation of the fluid pressure in the inner cavity and the outer cavity, the tube blank undergoes plastic deformation until it completely abuts against the forming curved surface, thus obtaining a formed component with a curved generatrix feature; Step 5: After the forming is completed, the pressure fluid in the inner cavity and the outer cavity is removed and the formed component is taken out.

8. The method for hydroforming a curved cylindrical part according to claim 7, characterized in that: Step 6: Cut off the excess of the formed component to obtain the final component.

9. The method for hydroforming a curved cylindrical part according to claim 7, characterized in that: In the step 4, the pressure difference between the inner cavity and the outer cavity is kept constant during the deformation of the tube blank.

10. The method for hydroforming a curved cylindrical part according to claim 7, characterized in that: In the step 1, the required single-layer or multi-layer tube blank is prepared by coil welding or spinning.

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