Magnetorheological elastomer and hydraulic combined pipe forming device and forming method

Abstract

The present invention provides a magnetorheological elastomer and hydraulic combined pipe forming device and forming method, wherein the forming device includes an upper mold and a lower mold, when the upper mold and the lower mold are combined with each other, a forming cavity is formed, the forming cavity has a radial bulging section and equal diameter sections at both ends of the radial bulging section, the forming cavity is consistent with the geometric surface features of the formed pipe fitting, the equal diameter section is used to place the two ends of the tube blank, the through hole of the tube blank is equipped with a magnetorheological elastomer, the magnetorheological elastomer is tubular, the through hole of the magnetorheological elastomer is used to fill hydraulic fluid, and the cavity wall of the forming cavity is also provided with an electromagnet, the electromagnet is used to adjust the elastic modulus of the corresponding position of the magnetorheological elastomer when current is passed. The present invention uses a combination of hydraulics and magnetorheological elastomers to form the tube blank, can differentially load the forming pressure to achieve accurate forming of the local features of the parts, and effectively prevent the occurrence of compression instability when the magnetorheological elastomer is used alone.

Description

Technical Field

[0001] The invention belongs to the technical field of flexible forming of pipe fittings, and in particular relates to a magnetorheological elastomer and hydraulic combined pipe fitting forming device and forming method. Background Art

[0002] Internal high pressure forming technology is mainly used in aerospace, automotive industry and precision instrument processing and manufacturing fields. Traditional internal high pressure forming adopts hydraulic bulging process, which makes the metal material plastically deformed by passing high pressure liquid into the tube blank, and finally obtains the required tube parts. Pipe fitting hydraulic forming technology can be divided into traditional internal high pressure forming technology with uniform liquid pressure loading, pulsating hydraulic forming technology and impact hydraulic forming technology proposed in recent years. At present, all technologies have been applied in actual parts production. Thin-walled large diameter ratio tube parts are difficult to form the local features contained in them by traditional internal high pressure forming technology due to their complex shapes. In view of the shape characteristics of such parts, some scholars have proposed to use magnetorheological elastomer as a filling medium for the flexible forming process of thin-walled metal pipe fittings. By applying a magnetic field to the forming device, the elastic modulus of each unit of the magnetorheological elastomer is changed to achieve differentiated loading of the forming force. Comprehensive analysis of two typical tube parts forming processes, liquid internal high pressure forming and magnetorheological elastomer forming, found that the two processes still have the following shortcomings:

[0003] (1) The use of liquid high pressure forming process alone cannot achieve differentiated forming pressure loading, resulting in the risk of rupture when forming thin-walled metal pipes with small features.

[0004] (2) If the magnetorheological elastomer forming process is used alone, the deformation of the rubber body is elastic and it is easy to become unstable after being squeezed, resulting in a decrease in the shape accuracy of the magnetorheological elastomer part. In addition, the use of rubber as a filling medium has poor fluidity, which makes it difficult to complete the forming operation of parts with high shape and size accuracy requirements. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a combined magnetorheological elastomer and hydraulic pipe forming device and forming method, which adopts a combination of hydraulics and magnetorheological elastomer to form the pipe blank, can differentially load the forming pressure to achieve precise forming of local features of the parts, and can also utilize the high-pressure forming characteristics of the hydraulic fluid to effectively prevent the rubber body that uses only magnetorheological elastomer in the prior art from easily undergoing compression instability during deformation.

[0006] In order to solve the above problems, the present invention provides a magnetorheological elastomer and hydraulic combined pipe forming device, comprising an upper mold and a lower mold. When the upper mold and the lower mold are combined with each other, a forming cavity is formed. The forming cavity has a radial bulging section and equal-diameter sections at both ends of the radial bulging section. The forming cavity is consistent with the geometric surface features of the formed pipe fitting. The equal-diameter sections are used to place the two ends of the tube blank. The through hole of the tube blank is equipped with a magnetorheological elastomer. The magnetorheological elastomer 3 is tubular. The through hole of the magnetorheological elastomer is used to fill hydraulic fluid. An electromagnet is also provided in the cavity wall of the forming cavity. The electromagnet is used to adjust the elastic modulus of the corresponding position of the magnetorheological elastomer when current is passed.

[0007] Preferably, the electromagnet comprises a first electromagnet, and the first electromagnet is arranged corresponding to the diameter-changing position of the forming cavity corresponding to the radial bulging section.

[0008] Preferably, the electromagnet further comprises a second electromagnet, and the second electromagnet is arranged corresponding to the forming cavity corresponding to the equal-diameter section.

[0009] Preferably, a first sealing plate and a second sealing plate are further provided in the equal-diameter section, and the first sealing plate and the second sealing plate are respectively arranged corresponding to the axial ends of the tube blank to form a seal when the hydraulic fluid is filled in the through hole of the magnetorheological elastomer, and the first sealing plate, the second sealing plate are slidably connected to the wall of the equal-diameter section.

[0010] Preferably, a first push plate and a second push plate are further provided in the equal diameter section, wherein the first push plate is located on a side of the first sealing plate away from the tube blank, and the second push plate is located on a side of the second sealing plate away from the tube blank.

[0011] Preferably, any one of the upper mold, the lower mold, the first sealing plate, the second sealing plate, the first push plate and the second push plate is made of non-magnetic steel; and / or the magnetorheological elastomer is a silicone rubber-based magnetorheological elastomer.

[0012] Preferably, the axial length of the magnetorheological elastomer is greater than the axial length of the tube blank.

[0013] The present invention also provides a magnetorheological elastomer and hydraulic combined pipe forming method, which is performed using the magnetorheological elastomer and hydraulic combined pipe forming device, and comprises:

[0014] Controlling the filling of hydraulic fluid into the through hole of the magnetorheological elastomer and controlling the first push plate and the second push plate to move toward each other to extrude the tube blank;

[0015] When the middle part of the tube blank bulges out and approaches the wall of the radial bulging section of the forming cavity, the first electromagnet is controlled to be energized.

[0016] Preferably, before the step of controlling the filling of hydraulic fluid into the through hole of the magnetorheological elastomer and controlling the first push plate and the second push plate to move toward each other to extrude the tube blank, the method further includes:

[0017] Control the second electromagnet to be energized.

[0018] Preferably, after the tube blank is formed, the first electromagnet and the second electromagnet are controlled to be demagnetized to discharge the hydraulic fluid filled in the through hole of the magnetorheological elastomer.

[0019] The present invention provides a magnetorheological elastomer and hydraulic combined pipe forming device and forming method, which fully utilizes the high-pressure force advantages of hydraulic fluid and the controllable loading advantages of magnetorheological elastomer, thereby ensuring a better forming effect on the pipe. That is, this technical method uses a combination of hydraulics and magnetorheological elastomers to form the pipe, which can differentially load the forming pressure to achieve precise forming of local features of the parts, and can also use the high-pressure forming characteristics of the hydraulic fluid to effectively prevent the rubber body that uses magnetorheological elastomer alone in the prior art from being prone to compression instability during deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of a pipe forming device according to an embodiment of the present invention;

[0021] Figure 2 for Figure 1 A schematic diagram of the state of the pipe forming device when the second electromagnet is energized for extrusion forming;

[0022] Figure 3 for Figure 1 A schematic diagram of the state of the pipe forming device in the embodiment of the present invention when the first electromagnet and the second electromagnet are energized to perform extrusion forming;

[0023] Figure 4 The magnetorheological elastomer part is obtained by using the pipe forming device according to the embodiment of the present invention.

[0024] The reference numerals are:

[0025] 1. Upper mold; 2. Lower mold; 3. Magnetorheological elastomer; 4. First electromagnet; 5. Second electromagnet; 6. First sealing plate; 7. First push plate; 8. Tube; 9. Second sealing plate; 10. Second push plate. DETAILED DESCRIPTION

[0026] See also Figures 1 to 4As shown, according to an embodiment of the present invention, a magnetorheological elastomer and hydraulic combined pipe forming device is provided, comprising an upper mold 1 and a lower mold 2. When the upper mold 1 and the lower mold 2 are combined with each other, a forming cavity is formed. The forming cavity has a radial bulging section and equal-diameter sections at both ends of the radial bulging section. The forming cavity is consistent with the geometric surface features of the formed pipe. The equal-diameter sections are used to place the two ends of the tube blank 8. A magnetorheological elastomer 3 is set in the through hole of the tube blank 8. The magnetorheological elastomer 3 is tubular. The through hole of the magnetorheological elastomer 3 is used to fill hydraulic fluid (such as water, oil or other flowable media). An electromagnet is also provided in the cavity wall of the forming cavity. The electromagnet is used to adjust the elastic modulus of the corresponding position of the magnetorheological elastomer 3 when current is passed. The hydraulic fluid can be, for example, non-conductive hydraulic oil. It can be understood that the diameter of the equal-diameter section is adapted to match the outer diameter of the axial end tube of the tube blank 8. In this technical solution, by making full use of the advantages of high pressure force of hydraulic fluid and the controllable loading of magnetorheological elastomer, it is possible to ensure a better forming effect on pipe fittings, that is, in this technical method, a combination of hydraulic pressure and magnetorheological elastomer is used to form the tube blank, which can realize the precise forming of the local features of the parts by differentially loading the forming pressure, and can also effectively prevent the rubber body of the prior art that uses magnetorheological elastomer alone from being easily compressed and unstable during deformation. It is worth clarifying that the hydraulic fluid in the present invention serves as the main driving force source for the expansion of the tube blank, while the combination of the electromagnet and the magnetorheological elastomer mainly strengthens the local mold of the tube blank 8.

[0027] Specifically, the electromagnet includes a first electromagnet 4, and the first electromagnet 4 is arranged corresponding to the diameter-changing position of the forming cavity corresponding to the radial expansion section. The aforementioned diameter-changing position is, for example, Figure 1 The local deformation position of the bulging section of the forming cavity shown in the figure is the intersection fillet of the horizontal and vertical walls. The first electromagnet 4 is set at this position to increase the elastic modulus of the magnetorheological elastomer 3 at the corresponding position when the first electromagnet 4 is energized, and the stiffness of the corresponding part is increased, that is, a direct current is passed through the first electromagnet 4 to generate an electromagnetic field with a certain field strength, so that the magnetic particles inside the magnetorheological elastomer near the small fillet are aggregated under the action of the electromagnetic force and hardened. Figure 3 As shown, it is helpful for the magnetorheological elastomer 3 to further flow toward the small fillet part of the mold forming cavity under the combined action of the electromagnetic suction force and the hydraulic pressure, so as to complete the mold forming of the part.

[0028] Furthermore, the electromagnet further comprises a second electromagnet 5, and the second electromagnet 5 is arranged corresponding to the forming cavity corresponding to the equal diameter section. Specifically, the arrangement position of the second electromagnet 5 corresponds to the axial end of the tube blank 8, that is, the axial end of the magnetorheological elastomer 3. Thus, before extrusion forming, a direct current can be supplied to the second electromagnet 5, so that an electromagnetic field is generated at the axial end of the magnetorheological elastomer 3. Under the action of the magnetic field, the magnetic particles at the axial end are aggregated and hardened. Figure 2 As shown, at this time, when an axial force is applied to the tube blank 8, the end of the hardened magnetorheological elastomer 3 can provide a good guide for the axial movement of the tube blank 8, thereby preventing the axial end of the tube blank 8 from deforming in the radial direction after being subjected to force.

[0029] Preferably, the equal diameter section is further provided with a first sealing plate 6 and a second sealing plate 9, which are respectively arranged corresponding to the axial ends of the tube blank 8 to form a seal when the hydraulic fluid is filled in the through hole of the magnetorheological elastomer 3, and the first sealing plate 6, the second sealing plate 9 are slidingly connected with the wall of the equal diameter section, and the sliding connection can be formed by, for example, a concave-convex structure respectively located on the outer peripheral edge of the sealing plate and the wall of the equal diameter section to ensure the stability of the circumferential position of the first sealing plate 6 and the second sealing plate 9 during the axial movement of the tube blank 8. When the axial length of the magnetorheological elastomer 3 is longer than the axial length of the tube blank 8, the first sealing plate 6 and the second sealing plate 9 will directly contact the end of the magnetorheological elastomer 3 and form a sealing structure, which has a simple structure. At the same time, for this situation, the sliding connection is very necessary, because the design of the sliding connection can effectively prevent the circumferential displacement of the first sealing plate 6 and the second sealing plate 9, that is, effectively prevent rotation, thereby preventing the relative rotation of the two from damaging the sealing effect.

[0030] Preferably, the equal diameter section is further provided with a first push plate 7 and a second push plate 10, wherein the first push plate 7 is located on the side of the first sealing plate 6 away from the tube blank 8, and the second push plate 10 is located on the side of the second sealing plate 9 away from the tube blank 8, and is used to apply axial pressure to the tube blank 8 to ensure axial feeding of the tube blank 8 during the expansion process of the tube diameter. It can be understood that the first sealing plate 6 and the second sealing plate 9 are both provided with joint connection holes for allowing external pressure fluid to enter the through hole of the magnetorheological elastomer 3, and the joint of the hydraulic pipeline is connected through the joint connection hole to realize the supply and return of hydraulic circulation. Similarly, based on the anti-interference of the structure, the first push plate 7 and the second push plate 10 are both constructed with avoidance through holes corresponding to the joint connection holes.

[0031] Any one of the upper mold 1, the lower mold 2, the first sealing plate 6, the second sealing plate 9, the first push plate 7, and the second push plate 10 is made of non-magnetic steel to ensure the controllability of the magnetic field of the first electromagnet 4 and the second electromagnet 5, and effectively prevent the occurrence of magnetic field leakage; and / or the magnetorheological elastomer is a silicone rubber-based magnetorheological elastomer with moderate stiffness.

[0032] As mentioned above, the axial length of the magnetorheological elastomer 3 is greater than the axial length of the tube blank 8. Specifically, the difference between the axial length of the magnetorheological elastomer 3 and the axial length of the tube blank 8 is d, 2mm≤d≤5mm, so as to ensure that the sealing plate can force the end of the magnetorheological elastomer 3 to undergo a slight deformation during the force application process, thereby achieving the sealing of the axial end. Preferably, the axial end of the magnetorheological elastomer 3 is in a bell-mouth structure, and the large mouth of the bell-mouth faces one side of the sealing plate (that is, toward the outside), so as to further ensure the sealing of the contact portion between the sealing plate and the magnetorheological elastomer 3.

[0033] The magnetorheological elastomer and hydraulic combined pipe forming device in this technical solution is particularly suitable for the forming of thin-walled large diameter ratio pipe parts. The technical solution of the present invention solves the defects of the traditional hydraulic forming process that the local features of the parts cannot be fully formed or the local area pressure is too high, causing rupture. By combining the magnetorheological elastomer with hydraulic forming, an electromagnetic field is locally applied to the magnetorheological elastomer during the hydraulic forming of the tube billet, the elastic modulus of the local unit of the magnetorheological elastomer is changed, and the magnetorheological elastomer is locally hardened, which can realize the differentiated loading of the forming pressure during the liquid filling forming of the tube billet, so as to complete the precise forming of the local features of the part.

[0034] According to an embodiment of the present invention, a magnetorheological elastomer and hydraulic combined pipe forming method is also provided, which is performed using the magnetorheological elastomer and hydraulic combined pipe forming device described above, and comprises:

[0035] Controlling the filling of hydraulic fluid into the through hole of the magnetorheological elastomer 3 and controlling the first push plate 7 and the second push plate 10 to move toward each other to extrude the tube blank 8, so that the middle part of the tube blank 8 approaches the radial bulging section;

[0036] When the middle part of the tube blank 8 bulges and approaches the wall of the radial bulging section of the forming cavity, the first electromagnet 4 is controlled to be energized. At this time, the first electromagnet 4 generates a corresponding electromagnetic field. Under the action of the electromagnetic field, the elastic modulus of the magnetorheological elastomer 3 at the corresponding position is increased, and the stiffness of the corresponding part is improved, that is, a direct current is passed through the first electromagnet 4 to generate an electromagnetic field with a certain field strength, so that the magnetic particles inside the magnetorheological elastomer near the small fillet are aggregated and hardened under the action of electromagnetic force, which helps the magnetorheological elastomer 3 to further flow to the small fillet of the mold forming cavity under the joint action of electromagnetic suction and hydraulic pressure, so as to complete the mold forming of the part and improve the forming quality of the pipe fitting.

[0037] Furthermore, before the step of controlling the hydraulic fluid to be filled into the through hole of the magnetorheological elastomer 3 and controlling the first push plate 7 and the second push plate 10 to move toward each other to extrude the tube blank 8, the method further includes:

[0038] The second electromagnet 5 is controlled to be energized. The second electromagnet 5 is set at a position corresponding to the axial end of the tube blank 8, that is, the axial end of the magnetorheological elastomer 3. In this way, before extrusion molding, a direct current can be passed through the second electromagnet 5 to generate an electromagnetic field at the axial end of the magnetorheological elastomer 3. Under the action of the magnetic field, the magnetic particles at the axial end are aggregated and hardened. Figure 2 As shown, at this time, when an axial force is applied to the tube blank 8, the end of the hardened magnetorheological elastomer 3 can provide a good guide for the axial movement of the tube blank 8, thereby preventing the axial end of the tube blank 8 from deforming in the radial direction after being subjected to force.

[0039] Preferably, when the tube is formed, the hydraulic fluid is discharged from the through hole of the forming cavity 3, and the direct current is stopped from being passed into the forming device. When the elastic modulus of the magnetorheological elastomer 3 inside the tube blank 8 is restored to its original state, the first push plate 7 and the second push plate 10 are controlled to move out of the equal diameter section along the axial direction and the first sealing plate 6 and the second sealing plate 9 are taken out, and the upper mold 1 and the lower mold 2 are separated to obtain the magnetorheological elastomer part. Furthermore, after the tube blank 8 is formed, the first electromagnet 4 and the second electromagnet 5 are controlled to be demagnetized and the hydraulic fluid filled in the through hole of the magnetorheological elastomer 3 is discharged. This method is suitable for when the hydraulic fluid is water, and can prevent the risk of electric shock to the operator during the unloading process.

[0040] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0041] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A magnetorheological elastomer and hydraulic combined pipe forming device, characterized in that: The invention comprises an upper die (1) and a lower die (2). When the upper die (1) and the lower die (2) are combined with each other, a forming cavity is formed. The forming cavity has a radially bulging section and equal-diameter sections at both ends of the radially bulging section. The forming cavity is consistent with the geometrical profile features of the formed pipe. The equal-diameter sections are used to place the two ends of a tube blank (8). A magnetorheological elastomer (3) is sleeved in a through hole of the tube blank (8). The magnetorheological elastomer (3) is tubular. The through hole of the magnetorheological elastomer (3) is used to The forming cavity is filled with hydraulic fluid, and an electromagnet is also provided in the cavity wall of the forming cavity. The electromagnet is used to adjust the elastic modulus of the corresponding position of the magnetorheological elastomer (3) when current is passed through it; the electromagnet includes a first electromagnet (4), and the first electromagnet (4) is arranged at a variable diameter position of the forming cavity corresponding to the radial bulging section, and the variable diameter position is the intersection fillet of the horizontal and vertical walls of the forming cavity, so as to strengthen the mold of the local area corresponding to the intersection fillet of the tube blank (8).

2. The pipe forming device according to claim 1, characterized in that: The electromagnet further comprises a second electromagnet (5), the second electromagnet (5) being arranged corresponding to the forming cavity corresponding to the equal-diameter section.

3. The pipe forming device according to any one of claims 1 to 2, characterized in that: The equal-diameter section is also provided with a first sealing plate (6) and a second sealing plate (9), the first sealing plate (6) and the second sealing plate (9) being respectively arranged corresponding to the axial ends of the tube blank (8) so as to form a seal when hydraulic fluid is filled into the through hole of the magnetorheological elastomer (3), and the first sealing plate (6) and the second sealing plate (9) are slidably connected to the wall of the equal-diameter section.

4. The pipe forming device according to claim 3, characterized in that: A first push plate (7) and a second push plate (10) are also provided in the equal diameter section. The first push plate (7) is located on a side of the first sealing plate (6) away from the tube blank (8), and the second push plate (10) is located on a side of the second sealing plate (9) away from the tube blank (8).

5. The pipe forming device according to claim 4, characterized in that: Any one of the upper mold (1), the lower mold (2), the first sealing plate (6), the second sealing plate (9), the first push plate (7), and the second push plate (10) is made of non-magnetic steel; and / or the magnetorheological elastomer is a silicone rubber-based magnetorheological elastomer.

6. The pipe forming device according to claim 3, characterized in that: The axial length of the magnetorheological elastomer (3) is greater than the axial length of the tube blank (8).

7. A method for forming a combined magnetorheological elastomer and hydraulic pipe fitting, characterized in that: The method is carried out by using a magnetorheological elastomer and hydraulic combined pipe forming device as claimed in any one of claims 4 to 5, comprising: Controlling the injection of hydraulic fluid into the through hole of the magnetorheological elastomer (3) and controlling the first push plate (7) and the second push plate (10) to move towards each other to extrude the tube blank (8); When the middle portion of the tube blank (8) bulges out and approaches the wall of the radially bulging section of the forming cavity, the first electromagnet (4) is controlled to be energized.

8. The pipe forming method according to claim 7, characterized in that: Before the step of controlling the filling of hydraulic fluid into the through hole of the magnetorheological elastomer (3) and controlling the first push plate (7) and the second push plate (10) to move towards each other to extrude the tube blank (8), the method further includes: The second electromagnet (5) is controlled to be energized.

9. The pipe forming method according to claim 8, characterized in that: After the tube blank (8) is formed, the first electromagnet (4) and the second electromagnet (5) are controlled to be demagnetized, thereby discharging the hydraulic fluid filled in the through hole of the magnetorheological elastomer (3).

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