Electromagnetic hydraulic forming device and forming method for metal bellows

Abstract

The present invention relates to the technical field of metal bellows forming technology, and more specifically to an electromagnetic hydraulic forming device and forming method for metal bellows, the forming device comprising: a lower sealing assembly; an outer guide assembly rotatably connected to the upper portion of the lower sealing assembly; a segmented positioning assembly disposed on the side wall of the outer guide assembly; an upper sealing assembly disposed above the segmented positioning assembly; a magnetic field generator disposed above the upper sealing assembly; the upper sealing assembly, the lower sealing assembly, and the outer guide assembly enclosing an extrusion cavity, in which a tube blank is placed; an annular cavity enclosed between the outer portion of the tube blank and the outer guide assembly; a forming die disposed within the annular cavity; and an inner guide piston disposed within the tube blank, forming a forming cavity between the inner portion of the tube blank and the outer portion of the inner guide piston. The forming die of the present invention can be instantly and completely pressed together, and under ultra-high-speed forming conditions, the tangential component of the instantaneous stress of the metal material is infinitely close to zero, thereby achieving springback-free forming of the metal material and improving the forming accuracy of the metal bellows.

Description

Technical Field

[0001] The present invention relates to the technical field of metal bellows forming, and in particular to an electromagnetic hydraulic forming device and a forming method for a metal bellows. Background Art

[0002] For most metal materials, under ultra-high speed forming conditions, some grain boundaries will be activated, while suppressing the generation and expansion of voids and cracks, thus improving the plasticity of the material to a certain extent. This theory has been widely recognized by the academic community. However, in actual production, it is necessary to increase the material strain rate to The strain rate of traditional high pressure forming method is generally 0.1s -1 The rate of ultra-high-speed forming is more than two orders of magnitude higher than that of traditional high-pressure forming methods, and it is extremely difficult to achieve this process with existing methods.

[0003] Electromagnetic forming, a new process for plastic molding of metal materials, enables ultra-high-speed metal forming. However, existing electromagnetic forming processes have stringent material requirements. Non-ferromagnetic materials cannot be used with this process. Ferromagnetic materials also require significantly different forming parameters depending on their magnetic strength, requiring extensive experimental verification to determine the process parameters. Furthermore, electromagnetic forming currently only allows for relatively simple shapes and is not suitable for forming metal materials with complex structures or complicated metal flow processes.

[0004] Metal bellows, particularly precision metal bellows used in aerospace, are primarily made of austenitic stainless steel, nickel-based superalloys, and titanium alloys. These materials exhibit significant springback during the forming process, with the amount of springback being relatively large depending on the material and the amount of deformation. For products like metal bellows, which have relatively complex shapes and experience significant springback, existing forming devices and methods struggle to accurately determine this amount through design calculations and experimental verification, severely impacting the forming accuracy and product quality of precision metal bellows.

[0005] To this end, the present application provides a metal bellows electromagnetic hydraulic forming device and forming method. Summary of the Invention

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides an electromagnetic hydraulic forming device and forming method for a metal bellows, which solves the technical problem in the prior art that due to the relatively complex shape of the metal bellows and the large forming rebound amount, it is difficult to accurately determine the forming rebound amount through design calculation and experimental verification, which seriously affects the forming accuracy and product quality of the precision metal bellows.

[0007] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides an electromagnetic hydraulic forming device for a metal bellows, which includes: a lower sealing component; an outer guide component, which is rotatably connected to the upper part of the lower sealing component; a slice positioning component, which is arranged on the side wall of the outer guide component; an upper sealing component, which is arranged above the slice positioning component and is connected to the outer guide component; a magnetic field generator, which is arranged above the upper sealing component and is connected to both the upper sealing component and the outer guide component; wherein the upper sealing component, the lower sealing component and the outer guide component enclose an extrusion cavity, the tube blank is placed inside the extrusion cavity, and the outside of the tube blank is connected to the outer guide component. An annular cavity is enclosed between the parts; the forming die is arranged inside the annular cavity and abuts against the slice positioning component and the outer guide component; the inner guide piston is placed inside the tube blank and connected to the upper sealing component, and a forming cavity is formed between the inside of the tube blank and the outside of the inner guide piston; the piston hole is arranged on the lower sealing component and corresponds to the inner guide piston; the injection hole is arranged on the side wall of the upper sealing component and communicates with the forming cavity; the outer guide component can drive the slice positioning component to rotate so that the slice positioning component moves away from the extrusion cavity, and the forming die is separated from the slice positioning component and abuts against the outer guide component and the tube blank.

[0008] Optionally, the lower sealing assembly includes: a lower sealing seat; a lower sealing outer ring, which is arranged between the tube blank and the outer guide assembly and connected to the lower sealing seat.

[0009] Optionally, the external guide assembly includes: a guide post, which is rotatably connected to the lower sealing seat; an upper support plate, which is mounted above the guide post and is connected to the guide post and the magnetic field generator; a guide post knob, which is arranged above the upper support plate and is connected to the guide post, thereby driving the guide post to rotate relative to the lower sealing seat.

[0010] Optionally, there are multiple guide pillars, and the multiple guide pillars are evenly spaced and arranged on the lower sealing seat along the horizontal direction.

[0011] Optionally, the segment positioning assembly includes: spacers, which are arranged at intervals on the side walls of the guide column along the vertical direction, and there are multiple spacers. A mold positioning groove is provided between two adjacent spacers, and the molding mold is arranged in the mold positioning groove; fixing bolts are connected between the guide column and the spacer.

[0012] Optionally, the volumes of the plurality of spacers gradually increase from top to bottom along the vertical direction.

[0013] Optionally, the upper sealing assembly includes: an upper sealing outer ring, which is arranged above the uppermost spacer and connected to the guide column and the tube blank; and an upper sealing member, which is arranged above the upper sealing outer ring.

[0014] The present invention further provides a method for electromagnetic hydraulic forming of a metal bellows, which is applied to the electromagnetic hydraulic forming device for a metal bellows according to the first aspect. The forming method comprises:

[0015] S1: Selection and design, according to the determined parameters of the target bellows, obtain the molding pressure P of the target bellows:

[0016] ;

[0017] in, is the tensile strength of the target bellows material, in MPa; is the wall thickness of the tube, in mm; d is the inner diameter of the tube, in mm;

[0018] Then the drum wave pressure P' is:

[0019] ;

[0020] Wherein, a is the drum wave coefficient; P is the target bellows forming pressure, unit MPa;

[0021] According to the Ampere force calculation formula: F=nILB, where n is the number of coil turns, unit: turns; I is the current intensity, unit: A; L is the coil length, unit: m; B is the magnetic induction intensity required for forming, unit: T;

[0022] In the actual forming process, the required Ampere force F' is:

[0023] ;

[0024] Among them, A' is the first-order dimensionless coefficient;

[0025] Then, through integration, the magnetic induction intensity B' required for the drum wave is:

[0026] ;

[0027] The magnetic induction intensity B required for forming is:

[0028] ;

[0029] S2: Install the molding device, position and install the outer guide assembly, the segmented positioning assembly, and the molding die, install the tube in the extrusion cavity, install the inner guide piston in the tube, and make the volume of the molding cavity minus the volume of the inner guide piston equal to the volume of the molding medium, and the volume of the molding medium equal to the volume of the target bellows cavity. Then install the upper and lower sealing assemblies, inject the molding medium into the molding cavity through the injection hole, and then pass current into the magnetic field generator;

[0030] S3: Bellows preforming, start the magnetic field generator, the inner guide piston moves downward through the piston hole, adjust the magnetic induction intensity, slowly increase from zero to B', and maintain for 3min~10min. After the tube is preformed, turn off the magnetic field generator and rotate the outer guide assembly to make the slice positioning assembly away from the extrusion cavity;

[0031] S4: Bellows forming, start the magnetic field generator, make the magnetic induction intensity reach B instantly, the inner guide piston moves downward at high speed, so that the forming mold pieces are all pressed together to obtain the target bellows, and then turn off the magnetic field generator.

[0032] The beneficial effects of the present invention are:

[0033] The present invention provides an electromagnetic hydraulic forming device and a forming method for a metal bellows. Before the tube blank is formed, an outer guide component is provided to be rotatably connected with a lower sealing component so that the outer guide component drives the slice positioning component to rotate to the inner side of the outer guide component, the forming die is installed on the slice positioning component, and then the tube blank, the inner guide piston, the upper sealing component and the lower sealing component are installed, wherein the upper sealing component, the lower sealing component and the outer guide component enclose an extrusion cavity, the tube blank is placed inside the extrusion cavity, and an annular cavity is enclosed between the outside of the tube blank and the outer guide component. Then, by rotating the outer guide component, the slice positioning component is driven to rotate away from the extrusion cavity, so that the inner wall of the forming die abuts against the tube blank, and the outer wall of the forming die abuts against the outer guide component. With this setup, when current is energized by the magnetic field generator and the molding medium is injected into the molding cavity, the forming dies are instantly pressed together during the tube blank forming process. Because an appropriately sized inner guide piston is pre-installed, the volume of the molding medium filled equals the volume of the target bellows cavity. Therefore, the molding medium does not need to be discharged during the entire forming process. This allows the electromagnetic field generated by the magnetic field generator to drive the inner guide piston to compress the molding medium within the molding cavity at high speed, thereby achieving an ultra-high-speed, internal, and high-pressure metal bellows forming process. Under ultra-high-speed forming conditions, some grain boundaries activate, suppressing the formation of cavities, cracks, and crack propagation in the metal material, thereby enhancing the plasticity of the metal material and producing metal bellows with a larger wave depth ratio. Furthermore, under ultra-high-speed forming conditions, the tangential component of the metal material's instantaneous stress approaches zero, achieving springback-free forming of the metal material and significantly improving the forming accuracy and product quality of precision metal bellows.

[0034] Furthermore, since the molding device of the present invention completely seals the molding cavity by providing an upper sealing assembly and a lower sealing assembly, and can replace inner guide pistons of different diameters, the volume of the molding medium filled before and after molding is equal to the volume of the target bellows inner cavity, that is, the volume in the molding cavity is constant, thereby avoiding the filling and discharge of the molding medium during the molding process and realizing an ultra-high-speed molding process.

[0035] Furthermore, the present invention utilizes the electromagnetic field generated by the magnetic field generator to form a high Lorentz force, thereby driving the liquid in the molding cavity to generate high pressure, thereby realizing the molding of metal materials, avoiding the limitations of electromagnetic molding material selection, and making the molding device and molding method suitable for non-ferromagnetic metal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic cross-sectional view of the electromagnetic hydraulic forming device for a metal bellows according to the present invention (in the forming device installation stage);

[0037] Figure 2 It is a cross-sectional schematic diagram of the electromagnetic hydraulic forming device for metal bellows of the present invention (bellows forming stage).

[0038] Description of reference numerals:

[0039] 1. Lower sealing assembly; 2. Lower sealing seat; 3. Lower sealing outer ring; 4. Outer guide assembly; 5. Guide post; 6. Upper support plate; 7. Guide post knob; 8. Slice positioning assembly; 9. Spacer; 10. Fixing bolt; 11. Molding die; 12. Upper sealing assembly; 13. Upper sealing outer ring; 14. Upper seal; 15. Magnetic field generator; 16. Inner guide piston; 17. Piston hole; 18. Injection hole. DETAILED DESCRIPTION

[0040] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Instead, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0041] The embodiment of the present invention provides a metal bellows electromagnetic hydraulic forming device, such as Figure 1 and Figure 2As shown, the forming device includes: a lower sealing component 1; an outer guide component 4, which is rotatably connected to the upper part of the lower sealing component 1; a slice positioning component 8, which is arranged on the side wall of the outer guide component 4; an upper sealing component 12, which is arranged above the slice positioning component 8 and is connected to the outer guide component 4; a magnetic field generator 15, which is arranged above the upper sealing component 12 and is connected to both the upper sealing component 12 and the outer guide component 4; wherein the upper sealing component 12, the lower sealing component 1 and the outer guide component 4 enclose an extrusion cavity, the tube blank is placed inside the extrusion cavity, and an annular cavity is enclosed between the outside of the tube blank and the outer guide component 4; a forming die 11, which is provided It is placed inside the annular cavity and abuts against the slice positioning component 8 and the outer guide component 4; the inner guide piston 16 is placed inside the tube blank and connected to the upper sealing component 12, and a molding cavity is formed between the inside of the tube blank and the outside of the inner guide piston 16; the piston hole 17 is provided on the lower sealing component 1 and corresponds to the inner guide piston 16; the injection hole 18 is provided on the side wall of the upper sealing component 12 and is connected to the molding cavity; the outer guide component 4 can drive the slice positioning component 8 to rotate, so that the slice positioning component 8 moves away from the extrusion cavity, and the molding die 11 is separated from the slice positioning component 8, and abuts against the outer guide component 4 and the tube blank.

[0042] For example, the forming device in this embodiment is cylindrical as a whole, the tube blank is entirely inside the forming device, and the magnetic field generator 15 is arranged directly above the forming cavity, so that the force generated during the electromagnetic hydraulic forming process acts evenly on the tube blank, thereby improving the forming quality of the metal bellows.

[0043] For example, the lower sealing assembly 1 is provided with a circular hole adapted for the installation of the outer guide assembly 4, facilitating the rotation of the outer guide assembly 4 relative to the lower sealing assembly 1. Since the slice positioning assembly 8 is connected to the outer guide assembly 4, the outer guide assembly 4 can drive the slice positioning assembly 8 to rotate synchronously, and the slice positioning assembly 8 rotates between a position within the annular cavity and a position away from the extrusion cavity. The slice positioning assembly 8 can specifically achieve a rotation angle of 45° to 360°, such as 60°, 90°, 180°, 270°, or 360°. When the slice positioning assembly 8 is away from the extrusion cavity, it can avoid the pressing of the molding die 11 during the molding process, thereby avoiding interference with the molding die 11 during the molding process.

[0044] For example, the molding device in this embodiment is provided with an upper sealing component 12 and a lower sealing component 1. The specific sealing method of the upper sealing component 12 and the lower sealing component 1 is to use a rubber sealing ring to ensure that the molding medium in the molding cavity does not leak.

[0045] For example, the end of the inner guide piston 16 facing the upper sealing assembly 12 is provided with a thread, and the end face of the upper sealing assembly 12 facing the inner guide piston 16 is provided with a screw hole, which facilitates the replacement of inner guide pistons 16 of different diameters, so that the molding device can prepare metal bellows of different sizes, thereby increasing the versatility of the molding device of this embodiment.

[0046] For example, the injection hole 18 in this embodiment is provided on the sidewall of the upper sealing assembly 12, connecting the exterior of the molding device with the molding cavity, facilitating the injection of molding medium into the molding cavity. The molding medium in this embodiment is not limited to liquid media such as water or oil. Gas can also be directly used as the molding medium, provided that the volume change due to compression is taken into account.

[0047] In one possible embodiment, Figure 1 and Figure 2 As shown, the lower sealing assembly 1 includes: a lower sealing seat 2; a lower sealing outer ring 3, which is arranged between the tube blank and the outer guide assembly 4 and connected to the lower sealing seat 2.

[0048] For example, in this embodiment, the lower sealing seat 2 is disc-shaped, and the lower sealing outer ring 3 is annular. The lower sealing outer ring 3 and the lower sealing seat 2 are connected by bolts, and the lower sealing outer ring 3 and the guide pillar 5 are simply abutted, facilitating assembly of the lower sealing outer ring 3. The lower sealing outer ring 3 and the tube blank are sealed, specifically using a sealing rubber ring to ensure that the molding medium in the molding cavity does not leak during the molding process.

[0049] In one possible embodiment, Figure 1 and Figure 2 As shown, the outer guide assembly 4 includes: a guide post 5, which is rotatably connected to the lower sealing seat 2; an upper support plate 6, which is sleeved on the guide post 5 and connected to the guide post 5 and the magnetic field generator 15; a guide post knob 7, which is arranged above the upper support plate 6 and connected to the guide post 5, thereby driving the guide post 5 to rotate relative to the lower sealing seat 2.

[0050] For example, a circular hole is provided on the lower sealing seat 2 to facilitate the insertion of the guide post 5 on the lower sealing seat 2 so that the guide post 5 can rotate relative to the lower sealing seat 2 .

[0051] Illustratively, the guide post knob 7 of this embodiment is fixedly connected to the guide post 5 , specifically, they can be welded, connected by bolts and nuts, or integrally formed, and then rotating the guide post knob 7 can drive the guide post 5 to rotate synchronously.

[0052] Exemplarily, the upper support plate 6 is mainly used to connect the guide column 5 and the magnetic field generator 15, so the upper support plate 6 and the magnetic field generator 15 are fixedly connected; and since the guide column 5 needs to rotate, the upper support plate 6 and the guide column 5 are movably connected so that the guide column 5 can rotate. The specific movable connection method is the existing technology and is not limited here.

[0053] In one possible embodiment, Figure 1 and Figure 2 As shown, there are multiple guide pillars 5 , and along the horizontal direction, the multiple guide pillars 5 are evenly spaced and arranged on the lower sealing seat 2 .

[0054] For example, the number of guide pillars 5 can be set to 2, and the two guide pillars 5 are symmetrically arranged on both sides of the inner guide piston 16. The side wall of each guide pillar 5 is provided with 5 spacers 9, and a mold positioning groove is provided between each two adjacent spacers 9, that is, 4 mold positioning grooves are provided. The spacers 9 on the side walls of the two guide pillars 5 are also symmetrically arranged, and the heights of the two opposite spacers 9 are the same. Figure 1 As shown, the topmost spacer 9 of the left guide post 5 and the topmost spacer 9 of the right guide post 5 are at the same height. This ensures that the relative die positioning grooves are at the same height, allowing the forming die 11 to be placed horizontally. Then, when the tube blank is placed vertically, the corrugations on the resulting corrugated tube are exactly perpendicular to the axial direction of the corrugated tube, ensuring the quality of the formed metal bellows. Depending on actual needs, the heights of the four die positioning grooves can be the same or different, and can be determined based on the corrugation requirements of the target metal bellows.

[0055] For example, the number of guide pillars 5 can be set to three, and the three guide pillars 5 are evenly spaced around the circumference of the inner guide piston 16. The sidewall of each guide pillar 5 is provided with five spacers 9, and a mold positioning groove is provided between each two adjacent spacers 9, that is, four mold positioning grooves are provided. The spacers 9 on the sidewalls of the three guide pillars 5 are also symmetrically arranged, and the heights of the three opposing spacers 9 are the same. The technical effects brought about by this arrangement are the same as those described above and will not be repeated here.

[0056] In one possible embodiment, Figure 1 and Figure 2 As shown, the slice positioning assembly 8 includes: spacers 9, which are arranged at intervals on the side walls of the guide column 5 along the vertical direction. There are multiple spacers 9, and a mold positioning groove is provided between two adjacent spacers 9. The molding mold 11 is provided in the mold positioning groove; a fixing bolt 10 is connected between the guide column 5 and the spacer 9.

[0057] For example, Figure 2As shown, the spacer 9 is fixedly connected to the guide post 5 via a fixing bolt 10. As the guide post 5 rotates, the spacer 9 also rotates. During the assembly phase of the forming apparatus, the spacer 9 is positioned inside the guide post 5, that is, facing the forming cavity. This allows the die positioning groove between two adjacent spacers 9 to accommodate the forming die 11. The forming die 11 is annular, with its inner ring abutting the tube blank and its outer ring abutting the guide post 5. During the bellows forming phase, the guide post 5 drives the spacer 9 to rotate, and the forming die 11 is suspended by the abutment force between the tube blank and the guide post 5. This arrangement ensures that when the magnetic field generator 15 is turned on, the forming die 11 abuts both the guide post 5 and the tube blank. Consequently, friction between the forming die 11, the guide post 5, and the tube blank is minimal. Compared to the downward pressure of the magnetic field generator 15, this friction is almost zero, allowing the forming die 11 to be instantly pressed together, resulting in the desired bellows.

[0058] For example, Figure 1 and Figure 2 As shown, five spacers 9 are provided on each side guide column 5. Specifically, the number of spacers 9 can be determined according to the actual needs of the metal bellows and is not specifically limited here.

[0059] For example, the position of the fixing bolt 10 on the guide column 5 can be moved up and down according to actual needs, facilitating adjustment of the fixed position of the spacer block 9 on the guide column 5. In this way, the distance between two adjacent spacer blocks 9 can be adjusted to accommodate the fixing of molding molds 11 of different heights. Specifically, multiple bolt holes can be provided in the guide column 5 in the vertical direction to accommodate the need for vertical adjustment of multiple fixing bolts 10.

[0060] In one possible embodiment, Figure 1 and Figure 2 As shown, along the vertical direction, from top to bottom, the volumes of the plurality of spacers 9 gradually increase.

[0061] For example, because the molding die 11 is initially positioned in the die positioning slot during the molding device installation phase, the weight of the molding die 11 is supported by the spacers 9. As the number of molding die 11 increases vertically, the spacers 9 positioned further down need to support the weight of the multiple molding die 11 above them, and thus, the weight they support increases. Therefore, by setting the volume of the lowest spacer 9 to the largest, the load-bearing capacity of the lower spacer 9 can be increased, preventing the weight of the molding die 11 from being supported solely by the spacers 9 and the fixing bolts 10, which could damage the connection between the fixing bolts 10 and the spacers 9.

[0062] In one possible embodiment, Figure 1 and Figure 2As shown, the upper sealing assembly 12 includes: an upper sealing outer ring 13, which is arranged above the uppermost spacer block 9 and connected to the guide column 5 and the tube blank; and an upper sealing member 14, which is arranged above the upper sealing outer ring 13.

[0063] For example, the upper sealing outer ring 13 and the upper sealing member 14 are connected by bolts, and the upper sealing outer ring 13 and the guide pillar 5 are in abutment with each other, thereby minimizing friction between the upper sealing outer ring 13 and the guide pillar 5 during the molding process. The upper sealing outer ring 13 and the tube blank are sealed, specifically using a sealing rubber ring, to ensure that the molding medium in the molding cavity does not leak during the molding process.

[0064] This embodiment also provides a method for electromagnetic hydraulic forming of a metal bellows, which is applied to the electromagnetic hydraulic forming device for the metal bellows in the above embodiment. The forming method includes:

[0065] S1: Selection and design, the target bellows material is 316L stainless steel, specifically 022Cr 17 Ni 12 Mo2, according to the determined parameters of the target bellows, the target bellows has an inner diameter of 31mm, an outer diameter of 42.7mm, a wave height of 5mm, a wave pitch of 4.5mm, a wave thickness of 3.3mm, a wave number of 17, and a straight side length of 4mm, the molding pressure P of the target bellows is obtained:

[0066] ;

[0067] in, The tensile strength of the target bellows material is 650 MPa; is the wall thickness of the tube, which is 0.5mm; d is the inner diameter of the tube, which is 31mm; the calculated P=20.97Mpa;

[0068] Then the drum wave pressure P' is:

[0069] ;

[0070] Wherein, a is the drum wave coefficient, which is generally 0.7-0.8. In this embodiment, a=0.75; P is the target bellows forming pressure, P=20.97 MPa; then the calculated value is P'=15.73 MPa;

[0071] According to the Ampere force calculation formula: F=nILB, where n is the number of coil turns, which is 5 turns; I is the current intensity, which is 10A; L is the coil length, which is 0.5m;

[0072] In the actual forming process, the required Ampere force F' is:

[0073] ;

[0074] Wherein, A' is a first-order dimensionless coefficient, generally 1.2 to 1.5, and in this embodiment, A'=1.5;

[0075] Then, through integration, the magnetic induction intensity B' required for the drum wave is:

[0076] ;

[0077] The magnetic induction intensity required for the drum wave is calculated to be B'=15.73÷25=0.63T;

[0078] The magnetic induction intensity B required for forming is:

[0079] ;

[0080] The magnetic induction intensity required for molding is calculated to be B=1.5×0.63=0.95T;

[0081] S2: Install the molding device. Position and install the outer guide assembly 4, the segment positioning assembly 8, and the molding die 11. In this embodiment, the parameters of the molding die 11 are a die inner diameter of 32.6mm, a die thickness of 4.0mm, and a spacing of 13.25mm between upper and lower adjacent molding dies 11. Select an inner guide piston 16 with a diameter of 20.5mm. Install the tube blank and the inner guide piston 16 in the molding cavity. In this embodiment, the diameter of the inner guide piston 16 is 20.5mm. Adjust the height of the spacer 9 so that the spacing between two adjacent spacers 9 is 13.25-4=9.25mm. The volume of the molding cavity minus the volume of the inner guide piston 16 equals the volume of the molding medium. The volume of the molding medium V0 equals the volume V1 of the target bellows cavity. Then, install the upper sealing assembly 12 and the lower sealing assembly 1. Inject the molding medium into the molding cavity through the injection hole 18. In this embodiment, the molding medium is deionized water. Then, pass a current I=10A through the magnetic field generator 15.

[0082] S3: Bellows preforming, start the magnetic field generator 15, the inner guide piston 16 moves downward through the piston hole 17, adjust the magnetic induction intensity, slowly increase from zero to B'=0.63T, and maintain it for 5 minutes. After the tube is preformed, turn off the magnetic field generator 15, rotate the outer guide assembly 4, and make the slice positioning assembly 8 away from the extrusion chamber;

[0083] S4: Bellows forming, start the magnetic field generator 15, make the magnetic induction intensity instantly reach B=0.95T, the inner guide piston 16 moves downward at high speed, so that the forming die 11 is completely pressed together to obtain the target bellows, and then turn off the magnetic field generator 15.

[0084] After step S4, magnetic field generator 15 is adjusted to flip the magnetic field direction 180° and restarted, causing inner guide piston 16 to slowly move upward to its initial position. Upper and lower sealing assemblies 12 and 1 are then disassembled, removing the desired metal bellows product. Finally, mold die 11 is removed and subsequently cleaned and dried, allowing the molding apparatus to be used for standby operation.

[0085] Illustratively, the above-mentioned forming method is applicable to a variety of commonly used materials such as austenitic stainless steel, martensitic stainless steel, titanium alloy or high-temperature alloy for preparing precision metal bellows products.

[0086] According to the forming method provided in this embodiment, since the forming method is a method step for a metal bellows electromagnetic hydraulic forming device provided in the first aspect embodiment of the present invention, the forming method has all the technical effects of a metal bellows electromagnetic hydraulic forming device, and will not be repeated here.

[0087] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0088] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0089] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A metal bellows electromagnetic hydraulic forming device, characterized in that: include: lower sealing assembly; An outer guide assembly, rotatably connected to the upper portion of the lower sealing assembly; A slice positioning assembly, arranged on the side wall of the outer guide assembly; An upper sealing assembly is disposed above the slice positioning assembly and is connected to the outer guide assembly; a magnetic field generator, disposed above the upper sealing assembly and connected to both the upper sealing assembly and the outer guide assembly; The upper sealing assembly, the lower sealing assembly and the outer guide assembly enclose an extrusion cavity, the tube blank is placed inside the extrusion cavity, and an annular cavity is enclosed between the outside of the tube blank and the outer guide assembly; A forming die is disposed inside the annular cavity and abuts against both the slice positioning assembly and the outer guide assembly; An inner guide piston is placed inside the tube blank and connected to the upper sealing assembly, with a forming cavity formed between the inside of the tube blank and the outside of the inner guide piston; The volume of the molding cavity minus the volume of the inner guide piston is equal to the volume of the molding medium, and the volume of the molding medium is equal to the volume of the inner cavity of the target bellows; When the bellows is formed, the inner guide piston moves downward at high speed to press the forming die sheets together; The end of the inner guide piston facing the upper sealing assembly is provided with a thread, and the end surface of the upper sealing assembly facing the inner guide piston is provided with a screw hole, so as to facilitate replacement of the inner guide piston with different diameters; a piston hole, provided on the lower sealing assembly and corresponding to the inner guide piston; A liquid injection hole is provided on the side wall of the upper sealing component and is communicated with the molding cavity; The outer guide assembly can drive the slice positioning assembly to rotate, so that the slice positioning assembly moves away from the extrusion cavity, and the forming die is separated from the slice positioning assembly and abuts against the outer guide assembly and the tube blank.

2. The electromagnetic hydraulic forming device for metal bellows according to claim 1, characterized in that: The lower sealing assembly comprises: Lower sealing seat; The lower sealing outer ring is arranged between the tube blank and the outer guide assembly and is connected to the lower sealing seat.

3. The electromagnetic hydraulic forming device for metal bellows according to claim 2, characterized in that: The outer guide assembly comprises: A guide post rotatably connected to the lower sealing seat; an upper support plate, sleeved on the guide pillar and connected to the guide pillar and the magnetic field generator; The guide post knob is arranged above the upper support plate and is connected to the guide post, thereby driving the guide post to rotate relative to the lower sealing seat.

4. The electromagnetic hydraulic forming device for metal bellows according to claim 3, characterized in that: There are multiple guide pillars, and along the horizontal direction, the multiple guide pillars are evenly spaced and arranged on the lower sealing seat.

5. The electromagnetic hydraulic forming device for metal bellows according to claim 3, characterized in that: The shard positioning component includes: Spacers are arranged at intervals on the side walls of the guide pillars along the vertical direction. There are multiple spacers, and a mold positioning groove is provided between two adjacent spacers. The molding mold is arranged in the mold positioning groove. A fixing bolt is connected between the guide column and the spacer block.

6. The electromagnetic hydraulic forming device for metal bellows according to claim 5, characterized in that: Along the vertical direction, from top to bottom, the volumes of the plurality of spacers gradually increase.

7. The electromagnetic hydraulic forming device for metal bellows according to claim 6, characterized in that: The upper sealing assembly comprises: An upper sealing outer ring is provided above the uppermost spacer and is connected to the guide pillar and the tube blank; The upper sealing member is arranged above the upper sealing outer ring.

8. A method for electromagnetic hydraulic forming of a metal bellows, applied to the electromagnetic hydraulic forming device for a metal bellows according to any one of claims 1 to 7, characterized in that: The molding method comprises: S1: Selection and design, according to the determined parameters of the target bellows, obtain the molding pressure P of the target bellows: ； in, is the tensile strength of the target bellows material, in MPa; is the wall thickness of the tube, in mm; d is the inner diameter of the tube, in mm; Then the drum wave pressure P' is: ； Wherein, a is the drum wave coefficient; P is the target bellows forming pressure, unit MPa; According to the Ampere force calculation formula: F=nILB, where n is the number of coil turns, unit: turns; I is the current intensity, unit: A; L is the coil length, unit: m; B is the magnetic induction intensity required for forming, unit: T; In the actual forming process, the required Ampere force F' is: ； Among them, A' is the first-order dimensionless coefficient; Then, through integration, the magnetic induction intensity B' required for the drum wave is: ； The magnetic induction intensity B required for forming is: ； S2: Installing the molding device, positioning and installing the outer guide assembly, the slice positioning assembly and the molding die, installing a tube blank in the extrusion cavity, installing the inner guide piston in the tube blank, the end of the inner guide piston facing the upper sealing assembly is provided with a thread, and the end surface of the upper sealing assembly facing the inner guide piston is provided with a screw hole to facilitate replacement of the inner guide pistons of different diameters, and the volume of the molding cavity minus the volume of the inner guide piston is equal to the volume of the molding medium, and the volume of the molding medium is equal to the volume of the target bellows cavity, then installing the upper sealing assembly and the lower sealing assembly, injecting the molding medium into the molding cavity through the injection hole, and then passing current through the magnetic field generator; S3: Bellows preforming: Start the magnetic field generator, move the inner guide piston downward through the piston hole, adjust the magnetic induction intensity, slowly increase from zero to B', and maintain it for 3 minutes to 10 minutes. After the tube is preformed, turn off the magnetic field generator, rotate the outer guide assembly, and make the slice positioning assembly face away from the extrusion chamber; S4: Bellows forming, start the magnetic field generator, make the magnetic induction intensity reach B instantly, the inner guide piston moves downward at high speed, so that the forming die pieces are all pressed together to obtain the target bellows, and then turn off the magnetic field generator.

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