A three-dimensional flexible bending device and forming method assisted by magnetorheological elastomers

Abstract

The present invention discloses a three-dimensional flexible bending device and a forming method assisted by magnetorheological elastomers, which relate to the technical field of intelligent three-dimensional forming manufacturing of metal pipes. The device includes a first guiding mechanism and a second guiding mechanism for guiding the pipes. A clamping mechanism for clamping the outer side of the pipes is provided at the right ends of the first guiding mechanism and the second guiding mechanism. A pushing mechanism for pushing the right end of the pipe is provided at the right end of the clamping mechanism. A bending die for bending the pipe to achieve deformation is provided at the left end of the first guiding mechanism. The first guiding mechanism, the second guiding mechanism, and the bending die are made of non-magnetic materials. The bending die is connected to a bending driving member for driving its rotation to achieve bending. Through the magnetorheological effect generated by the magnetorheological elastomers under the action of a magnetic field, the inner wall of the pipe is supported, and the defects such as wrinkling and instability that occur during the bending forming of the pipe can be effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of intelligent three-dimensional forming manufacturing of metal pipes, and specifically relates to a three-dimensional flexible bending device and forming method assisted by magnetorheological elastomers. Background Art

[0002] During the traditional bending forming process of pipes, phenomena such as wrinkling, instability, and cross-sectional distortion will inevitably occur. The emergence of three-dimensional free bending forming equipment has reduced the surface defects of pipes. However, when the bent pipe has a thin wall and a small bending radius, the above-mentioned defects will still appear on the surface of the formed pipe.

[0003] With the increasingly wide application of thin-walled pipes in the aerospace field, during the process of system pipeline layout, in order to fit the outer wall of the equipment cabin and avoid interference with other components, it is inevitable to use thin-walled pipes with various bending radii. Compared with thick-walled pipes, thin-walled pipes are extremely prone to defects such as outer wall thinning, cross-sectional distortion, and inner wall scratching during the bending forming process, resulting in a reduction in the service safety of aerospace equipment.

[0004] To address the above problems, a three-dimensional flexible bending device and forming method assisted by magnetorheological elastomers are now provided. Summary of the Invention

[0005] The purpose of the present invention is to provide a three-dimensional flexible bending device and forming method assisted by magnetorheological elastomers to solve the problems in the background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A three-dimensional flexible bending device assisted by magnetorheological elastomers includes a first guiding mechanism and a second guiding mechanism for guiding the pipe. A clamping mechanism for clamping the outer side of the pipe is provided at the right ends of the first guiding mechanism and the second guiding mechanism. A pushing mechanism for pushing the right end of the pipe is provided at the right end of the clamping mechanism. A bending die for bending the pipe to achieve deformation is provided at the left end of the first guiding mechanism. The first guiding mechanism, the second guiding mechanism, and the bending die are made of non-magnetic materials. The bending die is connected to a bending driving member for driving its rotation to achieve bending. The pipe where the bending die is located is filled with magnetorheological elastomers. A magnetic field generating unit for acting on the magnetorheological elastomers is provided on one side of the bending die. The magnetic field generating unit enables the magnetic particles in the magnetorheological elastomers to interact with each other to support the inner wall of the pipe to be formed.

[0008] On the basis of the above technical solutions, the present invention also provides the following optional technical solutions:

[0009] In an alternative solution: The magnetic field generating unit includes four pairs of electromagnets. A certain magnetic field can be generated between the electromagnets after being energized. Each electromagnet is composed of a coil, a pole column, and a pole head. The electromagnets are the first electromagnet and the second electromagnet, the third electromagnet and the fourth electromagnet, the fifth electromagnet and the sixth electromagnet, and the seventh electromagnet and the eighth electromagnet. After applying a DC power supply, the energized coil can generate a certain magnetic field. Under the action of the external coil, the ferromagnetic metal atoms inside the pole column are rearranged in a certain order. The atoms are orderly directed in the same direction under the action of the magnetic field. The pole column is magnetized after the coil is energized, increasing the magnetic flux. By controlling the magnitude of the current passing through the coil, a controllable high-intensity magnetic field can be formed in the air gap between the pole heads.

[0010] In an alternative solution: The magnetorheological elastomer is a smart material. The magnetorheological elastomer is made of addition-cured silicone rubber, micron-sized iron powder, and additives. The magnetorheological elastomer will produce a magnetorheological effect under magnetic field conditions.

[0011] In an alternative solution: The propulsion mechanism includes a pressing ring corresponding to the end face of the pipe, and the pressing ring is connected to a hydraulic push rod for pushing it.

[0012] In an alternative solution: The material of the bending die is selected as 5Cr21Mn9Ni4N non-magnetic die steel, and the materials of the first guiding mechanism and the second guiding mechanism are selected as ceramics.

[0013] In an alternative solution: It further includes an elastic sleeve for inserting into the interior of the pipe. An elastic steel wire column is disposed through the middle position inside the elastic sleeve. The right end of the elastic steel wire column is connected to a material-receiving hydraulic push rod for pulling it to expand and contract. The material-receiving hydraulic push rod is arranged at the right end of the elastic sleeve. A plugging head is provided at the left end of the elastic steel wire column. The plugging head is in sliding fit with the inner wall of the pipe. A filling cavity is provided at the left end of the elastic sleeve. A piston block is in sliding fit in the filling cavity. The piston block is fixedly connected to the inner wall of the filling cavity through a return spring. When the magnetorheological elastomer is sent into the interior of the pipe, the magnetorheological elastomer is first stored inside the filling cavity. At this time, the plugging head is in pressing contact with the left end of the elastic sleeve. Then the left end of the elastic sleeve is inserted into the interior of the pipe. When reaching the target position, the elastic steel wire column is driven to move leftward by the material-receiving hydraulic push rod, so that the plugging head is separated from the left end of the elastic sleeve. At this time, the magnetorheological elastomer in the filling cavity will flow out and fill the position of the bending die. During the bending process, under the action of the magnetic field device, the supporting performance of the magnetorheological elastomer will change. As the pipe is pushed, the position of the elastic sleeve remains unchanged. In this way, the plugging head will drive the magnetorheological elastomer to slide inside the pipe. In this way, it is not necessary to fill the entire interior of the pipe with the magnetorheological elastomer, reducing the waste of resources. And after forming, the plugging head is driven to move rightward by the material-receiving hydraulic push rod, so as to press the magnetorheological elastomer into the filling cavity, thereby realizing the recycling of the magnetorheological elastomer filling cavity. When the action of the magnetic field is lost, the magnetorheological elastomer can be switched to a fluid state.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] In the present invention, the magnetorheological elastomer is utilized to generate a magnetorheological effect under a magnetic field to play a supporting role inside the pipe. The magnetorheological effect refers to the characteristic that the shear modulus of the magnetorheological elastomer suddenly increases under the action of a magnetic field. When the applied magnetic field is removed, the shear modulus of the elastomer returns to its original state. By utilizing this characteristic of the magnetorheological elastomer, adding a magnetic field generating unit to the three-dimensional free bending forming equipment can effectively solve defects such as wrinkling, cross-section distortion, and wall thickness reduction that occur during the bending forming of the pipe;

[0016] By adding the magnetorheological elastomer intelligent material during the bending forming process of the pipe, the present invention effectively solves problems such as poor surface quality and serious defects of the formed pipe;

[0017] The device of the present invention is simple and the operation is simple, effectively solving the problem of defects on the surface of the formed pipe by the three-dimensional free bending equipment, which is of great significance for improving the quality of the formed workpiece. Brief Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of Embodiment 1 of the present invention.

[0019] Figure 2 This is a schematic structural diagram of the terminal post of the present invention.

[0020] Figure 3 This is a schematic structural diagram of the magnetic field generating unit of the present invention.

[0021] Figure 4 This is a schematic structural diagram of Embodiment 2 of the present invention.

[0022] Figure 5 This is a schematic structural diagram of Structure A in Embodiment 2 of the present invention.

[0023] Annotation of reference numerals in the drawings: bending die 1, first electromagnet 2, second electromagnet 3, magnetic field generating unit 4, third electromagnet 10, fifth electromagnet 11, seventh electromagnet 12, fourth electromagnet 13, sixth electromagnet 14, eighth electromagnet 15, external coil 16, terminal post 17, pole head 18, magnetorheological elastomer 19;

[0024] Material receiving hydraulic push rod 31, elastic wire column 32, elastic sleeve 33, filling cavity 34, return spring 35, piston block 36, plugging head 37. Detailed implementation manners

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0026] In Embodiment 1, as Figures 1 - 3 shown, a three-dimensional flexible bending device assisted by magnetorheological elastomer includes a first guiding mechanism 5 and a second guiding mechanism 6 for guiding a pipe 7. A clamping mechanism 8 for clamping the outer side of the pipe 7 is provided at the right ends of the first guiding mechanism 5 and the second guiding mechanism 6. A pushing mechanism 9 for pushing the right end of the pipe 7 is provided at the right end of the clamping mechanism 8. A bending die 1 for bending the pipe 7 to achieve deformation is provided at the left end of the first guiding mechanism 5. The first guiding mechanism 5, the second guiding mechanism 6 and the bending die 1 are made of non-magnetic materials. The bending die 1 is connected to a bending driving member for driving its rotation to achieve bending. The pipe 7 where the bending die 1 is located is filled with a magnetorheological elastomer 19. A magnetic field generating unit 4 for acting on the magnetorheological elastomer 19 is provided on one side of the bending die 1. The magnetic field generating unit 4 enables the magnetic particles in the magnetorheological elastomer 19 to interact with each other to support the inner wall of the pipe to be formed;

[0027] The magnetic field generating unit 4 includes four pairs of electromagnets. A certain magnetic field can be generated between the electromagnets after being energized. Each electromagnet is composed of a coil 16, a pole column 17, and a pole head 18. The electromagnets are the first electromagnet 2 and the second electromagnet 3, the third electromagnet 10 and the fourth electromagnet 13, the fifth electromagnet 11 and the sixth electromagnet 14, the seventh electromagnet 12 and the eighth electromagnet 15. After applying a DC power supply, the energized coil 16 can generate a certain magnetic field. Under the action of the external coil 16, the ferromagnetic metal atoms inside the pole column 17 are rearranged according to a certain order rule, and the atoms are orderly directed in the same direction under the action of the magnetic field. The pole column 17 is magnetized after the coil 16 is energized, increasing the magnetic flux. By controlling the magnitude of the current passing through the coil, a controllable high-intensity magnetic field can be formed in the air gap between the pole heads;

[0028] The magnetorheological elastomer 19 is a smart material. The magnetorheological elastomer is made of addition-cured silicone rubber, micron-sized iron powder, and additives. The magnetorheological elastomer will produce a magnetorheological effect under magnetic field conditions;

[0029] The propulsion mechanism 9 includes a pressing ring corresponding to the end face of the pipe 7, and the pressing ring is connected to a pushing hydraulic rod for pushing it;

[0030] The material of the bending die 1 is selected as 5Cr21Mn9Ni4N non-magnetic die steel, and the materials of the first guiding mechanism 5 and the second guiding mechanism 6 are selected as ceramics;

[0031] During actual use, a magnetorheological elastomer material is prepared with a silicone mold, addition-cured silicone rubber, additives, and ultrafine iron powder. According to the different materials of the pipe to be bent, the optimal magnetic powder content added when preparing the magnetorheological elastomer also varies. When bending 304 stainless steel pipes, the magnetorheological elastomer is equipped with a magnetic powder content of 60%, addition-cured silicone rubber piston block of 36%, and additives of 4%. The prepared elastomer sample is subjected to a compression test, and the relationship between stress σ and strain ε is obtained by using a universal testing machine to conduct a compression experiment on the magnetorheological elastomer sample. Using the Mooney-Rivlin metal rubber constitutive equation: The test results are coupled, and finally the material constants C10 and C01 are determined. At the same time, the material parameters are input into the hyperelastic material module of the abaqus simulation software, and the forming process of the pipe is simulated by using simulation. According to the simulation results, the forming quality of the pipe is predicted when the eccentricity is 4mm, 6mm, 8mm, 10mm, 12mm... The relationship between the magnetic field strength T, the pipe eccentricity U, and the bending radius R is established, and the appropriate magnetic field strength is adjusted according to the bending radius of the pipe to be formed;

[0032] Then, based on the established U-R-T relationship, the bending radius of the stainless steel pipe when U = 12 is analyzed, and the optimal magnetic field strength required for bending at this time is obtained according to the previous simulation results;

[0033] The parsed program is input into the three-dimensional free bending program system, and the output current is adjusted to 10 amperes. At this time, the magnetic field strength at the center of the bending die is measured to be 2.3 Tesla using a gaussmeter;

[0034] The magnetorheological fluid in the fluid state is poured into the interior of the pipe for curing. After the magnetorheological fluid is cured into a magnetorheological elastomer, the pipe to be formed is inserted into the three-dimensional free forming device through the die orifice at the front end of the bending die. When the pipe passes through the connection between the guiding mechanism and the bending die, the magnetic particles in the magnetorheological elastomer will be affected by the magnetic field generated by the magnetic field generator, and the magnetic particles in the elastomer will play a supporting role inside the pipe; the pipe is bent by the offset of the bending die. While the bending die is moving, the magnetic field generator moves synchronously with the bending die, and the pipe is formed into a predetermined shape;

[0035] Example 2

[0036] Such as Figures 4 - 5As shown in the figure, the three-dimensional flexible bending device assisted by magnetorheological elastomers further includes an elastic sleeve 33 for inserting into the interior of the pipe 7. An elastic wire column 32 is passed through the middle position inside the elastic sleeve 33. The right end of the elastic wire column 32 is connected to a material collecting hydraulic push rod 31 for pulling it to expand and contract. The material collecting hydraulic push rod 31 is arranged at the right end of the elastic sleeve 33. A plugging head 37 is provided at the left end of the elastic wire column 32. The plugging head 37 is in sliding fit with the inner wall of the pipe 7. A filling cavity 34 is provided at the left end of the elastic sleeve 33. A piston block 36 is in sliding fit in the filling cavity 34. The piston block 36 is fixedly connected to the inner wall of the filling cavity 34 through a return spring 35. When the magnetorheological elastomer 19 is sent into the interior of the pipe 7, the magnetorheological elastomer 19 is first stored inside the filling cavity 34. At this time, the plugging head 37 is in pressing contact with the left end of the elastic sleeve 33. Then the left end of the elastic sleeve 33 is inserted into the interior of the pipe 7. When the target position is reached, the elastic wire column 32 is driven to move leftward by the material collecting hydraulic push rod 31, so that the plugging head 37 is separated from the left end of the elastic sleeve 33. At this time, the magnetorheological elastomer 19 in the filling cavity 34 will flow out and fill the position where the bending die 1 is located. During the bending process, under the action of the magnetic field device, the supporting performance of the magnetorheological elastomer 19 will change. As the pipe 7 is pushed, the position of the elastic sleeve 33 remains unchanged. In this way, the plugging head 37 will drive the magnetorheological elastomer 19 to slide inside the pipe 7. In this way, it is not necessary to fill the entire interior of the pipe 7 with the magnetorheological elastomer, reducing the waste of resources. And after forming, the plugging head 37 is driven to move rightward by the material collecting hydraulic push rod 31, so as to press the magnetorheological elastomer into the filling cavity 34, thereby realizing the recycling of the magnetorheological elastomer filling cavity 34. When the action of the magnetic field is lost, the magnetorheological elastomer can be switched to a fluid state.

[0037] As described above, the above is only the specific implementation manner of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure can easily think of changes or substitutions, which should all be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A three-dimensional flexible bending device assisted by magnetorheological elastomers, comprising a first guiding mechanism (5) and a second guiding mechanism (6) for guiding a pipe (7). A clamping mechanism (8) for clamping the outer side of the pipe (7) is provided at the right ends of the first guiding mechanism (5) and the second guiding mechanism (6). A propulsion mechanism (9) for pushing the right end of the pipe (7) is provided at the right end of the clamping mechanism (8). A bending die (1) for bending the pipe (7) to achieve deformation is provided at the left end of the first guiding mechanism (5), characterized in that, The first guiding mechanism (5), the second guiding mechanism (6) and the bending die (1) are made of non-magnetic materials. The bending die (1) is connected to a bending driving member for driving its rotation to achieve bending. The inside of the pipe (7) where the bending die (1) is located is filled with a magnetorheological elastomer (19). A magnetic field generating unit (4) for acting on the magnetorheological elastomer (19) is provided on one side of the bending die (1). The magnetic field generating unit (4) enables the magnetic particles in the magnetorheological elastomer (19) to interact with each other to support the inner wall of the pipe to be formed. It further includes an elastic sleeve (33) for inserting into the pipe (7). An elastic steel wire column (32) is disposed through the middle position inside the elastic sleeve (33). The right end of the elastic steel wire column (32) is connected to a material collecting hydraulic push rod (31) for pulling its telescopic movement. The material collecting hydraulic push rod (31) is arranged at the right end of the elastic sleeve (33). A plugging head (37) is provided at the left end of the elastic steel wire column (32). The plugging head (37) is in sliding fit with the inner wall of the pipe (7). A filling cavity (34) is provided at the left end of the elastic sleeve (33). A piston block (36) is in sliding fit in the filling cavity (34). The piston block (36) is connected and fixed to the inner wall of the filling cavity (34) through a return spring (35).

2. The three-dimensional flexible bending device assisted by magnetorheological elastomer forming according to claim 1, wherein The magnetic field generating unit (4) includes four pairs of electromagnets. A certain magnetic field can be generated between the electromagnets after being energized. Each electromagnet is composed of a coil (16), a pole column (17), and a pole head (18). The electromagnets are the first electromagnet (2) and the second electromagnet (3), the third electromagnet (10) and the fourth electromagnet (13), the fifth electromagnet (11) and the sixth electromagnet (14), the seventh electromagnet (12) and the eighth electromagnet (15). After passing through a DC power supply, the energized coil (16) generates a certain magnetic field. Under the action of the external coil (16), the ferromagnetic metal atoms inside the pole column (17) are rearranged in a certain order. The atoms are orderly directed in the same direction under the action of the magnetic field. The pole column (17) is magnetized after the coil (16) is energized, increasing the magnetic flux. By controlling the magnitude of the current passing through the coil, a controllable high-intensity magnetic field is formed in the air gap between the pole heads.

3. The three-dimensional flexible bending device assisted by magnetorheological elastomer forming according to claim 1, wherein The magnetorheological elastomer (19) is made of addition-cured silicone rubber, micron-sized iron powder and additives. The magnetorheological elastomer will produce a magnetorheological effect under magnetic field conditions.

4. The three-dimensional flexible bending device assisted by magnetorheological elastomer forming according to claim 1, characterized in that, The propulsion mechanism (9) includes a pressing ring corresponding to the end face of the pipe (7). The pressing ring is connected to a pushing hydraulic rod for pushing it.

5. The three-dimensional flexible bending device assisted by magnetorheological elastomer forming according to claim 1, wherein The material of the bending die (1) is selected as 5Cr21Mn9Ni4N non-magnetic die steel, and the materials of the first guiding mechanism (5) and the second guiding mechanism (6) are selected as ceramics.

6. A forming method of a three-dimensional flexible bending device assisted by magnetorheological elastomer forming according to any one of claims 1-5, characterized in that, It includes the following steps: Step 1: Prepare the magnetorheological elastomer intelligent material using a silicone mold, addition-cured silicone rubber, additives, and ultrafine iron powder. Depending on the material of the pipe to be bent, the optimal magnetic powder content added during the preparation of the magnetorheological elastomer varies. After preparing the magnetorheological elastomer, use a universal testing machine to conduct a compression experiment on the magnetorheological elastomer sample to obtain the relationship between stress σ and strain ε. Use the Mooney-Rivlin constitutive equation for metal rubber: Couple the test results, and finally determine the material constants C10 and C01. At the same time, input the material parameters into the hyperelastic material module of the abaqus simulation software, and use the simulation to simulate the forming process of the pipe. According to the simulation results, predict the forming quality of the pipe when the eccentricity is 4mm, 6mm, 8mm, 10mm, 12mm...... In the Origin software, use the formula to fit the relationship between the magnetic field strength H, the eccentricity U of the pipe, and the bending radius R, and adjust the appropriate magnetic field strength according to the bending radius of the pipe to be formed; Step 2: Pour the magnetorheological fluid in a fluid state into the interior of the pipe for curing. After the magnetorheological fluid cures into the magnetorheological elastomer (19), insert the pipe to be formed (7) into the three-dimensional free forming device through the die orifice at the front end of the bending die (1). The pipe (7) passes through the second guiding mechanism (6) and the first guiding mechanism (5) under the action of the propulsion mechanism (9). At the connection between the first guiding mechanism (5) and the bending die (1), the magnetic particles in the magnetorheological elastomer (19) will be affected by the magnetic field generated by the magnetic field generating unit (4). The magnetic particles in the elastomer will support the interior of the pipe under the action of the magnetic field; Step 3: Bend the pipe (7) by offsetting the bending die (1). While the bending die is moving, the magnetic field generating unit moves synchronously with the bending die.

7. A forming method of the three-dimensional flexible bending device assisted by magnetorheological elastomer forming according to any one of claim 6, characterized in that, When feeding the magnetorheological elastomer (19) into the interior of the pipe (7), the magnetorheological elastomer (19) is first stored inside the filling cavity (34). At this time, the plugging head (37) is in pressing contact with the left end of the elastic sleeve (33). Then, the left end of the elastic sleeve (33) is inserted into the interior of the pipe (7). When the target position is reached, the elastic wire column (32) is driven to move leftward by the material receiving hydraulic push rod (31), so that the plugging head (37) is separated from the left end of the elastic sleeve (33). At this time, the magnetorheological elastomer (19) in the filling cavity (34) will flow out and fill the position where the bending die (1) is located. During the bending process, under the action of the magnetic field device, the support performance of the magnetorheological elastomer (19) will change. As the pipe (7) is pushed, the position of the elastic sleeve (33) remains unchanged. In this way, the plugging head (37) will drive the magnetorheological elastomer (19) to slide inside the pipe (7). In this way, it is not necessary to fill the entire interior of the pipe (7) with the magnetorheological elastomer, reducing the waste of resources. After forming, the plugging head (37) is driven to move rightward by the material receiving hydraulic push rod (31), so as to press the magnetorheological elastomer into the interior of the filling cavity (34), thus realizing the recycling of the magnetorheological elastomer filling cavity (34). When the action of the magnetic field is lost, the magnetorheological elastomer switches to a fluid state.

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