In-situ self-resistance heating-magnetic pulse bending forming process and device

Abstract

The present invention discloses an in-situ self-resistance heating-magnetic pulse bending forming process and device, which relates to the field of metal plastic processing and forming technology. The bending forming process includes the following steps: placing the grid rib wall panel workpiece to be processed on the forming die, and fixing and clamping it by the edge clamping block, and suspending the driving blocks mutually above the grid rib wall panel workpiece; the grid rib wall panel workpiece is heated and softened to the target heating temperature by self-resistance heating; the driving block moves at high speed under the action of strong Lorentz force and hits the grid rib wall panel workpiece to bend and deform it; the grid rib wall panel workpiece is taken out after natural cooling. The present invention utilizes the Joule heat effect and the pure electroplastic effect to improve the bending formability of the titanium alloy grid rib wall panel, and sets a driving block of a specific structure embedded with the rib plate, thereby increasing the forming action area and the Lorentz force while further improving the forming effect, solving the problem of low electrical conductivity of the titanium alloy wall panel, and enhancing the deformation efficiency at the same time, avoiding instability during the bending process of the rib plate.

Description

Technical Field

[0001] The invention relates to the technical field of metal plastic processing and forming, in particular to an in-situ self-resistance heating-magnetic pulse bending forming process and device. Background Art

[0002] Grid-ribbed wall panels represented by spacecraft wall panels, cabin sections, rudder wings, engine casings, etc. are key load-bearing components in aerospace launch equipment. They use lightweight and high-strength materials (high-strength aluminum alloys, titanium alloys) and multi-rib overall weight-reducing structures, and are an important development direction for high-performance lightweight components in the aerospace field.

[0003] However, for Figure 1 For the mesh rib wall panel workpiece made of titanium alloy shown in the figure, the existing bending forming methods of titanium alloy mesh rib wall panels include rolling forming, incremental bending forming, creep aging forming, shot peening forming and electromagnetic forming. For example, the scientific research team of the creator of the present invention proposed an electrically assisted bending forming process method for high-temperature titanium alloy mesh rib wall panels (Chinese invention patent, publication number CN111957777A). By applying the idea of ​​pulse current assisted forming to the overall forming process of high-temperature titanium alloy mesh rib wall panels, a new electrically assisted bending forming process for high-temperature titanium alloy mesh rib integral wall panels is innovatively proposed. It is expected to improve the formability of high-temperature titanium alloy mesh rib integral wall panels by using the self-resistance heating effect and electroplastic effect of the material, and realize the integrated and precise control of the formability of high-temperature titanium alloy mesh rib integral wall panels through the coordinated control of electric-heat-force field, solving the technical problems that the conventional cold deformation or warm deformation method for forming its mesh rib integral wall panels has high equipment tonnage requirements, and the formation defects such as cracking of the rib root, instability deformation of the rib upper end, and dimensional tolerance are prone to occur during the forming process.

[0004] However, in actual applications, the above technology uses a rigid mechanical force to drive the bending punch to directly act on the top center of the high-temperature titanium alloy grid rib wall panel workpiece to achieve overall forming. There are problems such as the rib plate being easily unstable when subjected to instantaneous high-speed impact and the small action area resulting in low deformation efficiency. Especially when the vertical height of the grid rib wall is large, the possibility of instability is greater and the forming quality is difficult to guarantee.

[0005] Electromagnetic forming is widely used because it is superior to traditional quasi-static forming methods and other high-energy forming methods (explosive forming, electro-hydraulic forming, etc.) in improving strain distribution during processing, reducing workpiece wrinkling and springback defects, and has high production efficiency. However, titanium alloy is a difficult-to-deform material with the disadvantages of high deformation resistance, easy cracking, and easy oxidation under high temperature conditions. In addition, its electrical conductivity is low and it is not easy to form electromagnetically (the eddy current intensity formed is low). In addition, electromagnetic forming still has the phenomenon that the rib plate is easy to become unstable under instantaneous high-speed impact with extremely large loads. When the electromagnetic coil acts on the rib (rib top), its action area is small, resulting in insufficient Lorentz force and low deformation efficiency. As a result, the effect of bending and forming titanium alloy grid rib wall panels using electromagnetic forming technology is still not ideal. Summary of the invention

[0006] In view of the above-mentioned defects and shortcomings, the present invention provides an in-situ self-resistance heating-magnetic pulse bending forming process and device suitable for mesh rib wall panels, which utilizes Joule thermal effect and pure electroplastic effect to improve the bending formability of titanium alloy mesh rib wall panels, and arranges a driving block with a specific structure and good conductive effect that is embedded with the rib plate in the forming area between the electromagnetic coil and the mesh rib wall panel, thereby increasing the forming action area and the Lorentz force while further improving the forming effect, solving the problem of low electrical conductivity of the titanium alloy wall panels, while enhancing the deformation efficiency and maintaining the stability of the rib plates.

[0007] In order to solve the above technical problems, a technical solution adopted by the present invention is:

[0008] An in-situ self-resistance heating-magnetic pulse bending forming process comprises the following steps:

[0009] S1. Sample clamping: Place the grid rib wall panel workpiece to be processed on the positioning table on both sides of the forming groove of the forming die, and fix and clamp the two ends of the grid rib wall panel workpiece by cooperating with the positioning table through the edge pressing block, the rib plate surface of the grid rib wall panel workpiece faces upward, and suspend the copper material driving block directly above the grid rib wall panel workpiece;

[0010] S2, self-resistance heating: start the pulse power generator, and pass a preset high-frequency strong pulse current into the grid rib wall panel workpiece through the electrodes on the edge clamping blocks on both sides, so that the grid rib wall panel workpiece is self-resistance heated and heated to the target heating temperature;

[0011] S3, magnetic pulse bending: the electromagnetic pulse processing system discharges the electromagnetic coil above the driving block, the electromagnetic coil generates a magnetic field, and a strong Lorentz force is generated in the driving block, so that the driving block moves at a high speed and hits the straight wall plate at the bottom end of the grid rib wall plate workpiece, so that the straight wall plate is bent and deformed until it is pressed against the forming groove of the forming die;

[0012] S4, power off cooling: turn off the pulse power generator to allow the bent mesh rib wall panel workpiece to cool naturally to room temperature;

[0013] S5. Take out the sample: turn off the electromagnetic pulse processing system, remove the electromagnetic coil, the driving block and the edge pressing block, and take out the bent mesh rib wall panel workpiece from the forming die.

[0014] Furthermore, in step S2, the preset pulse current parameters are set as: steady current mode, frequency 500 Hz, pulse width 100 Hz, duty cycle 5%, current density 10 A / mm2 in the self-resistance heating stage 2 ~30A / mm 2 , the self-resistance heating time is set to 10s~30s, and the target heating temperature is set to 500℃~700℃; in step S3, while the magnetic pulse circuit of the electromagnetic pulse treatment system is discharged, the current density of the high-frequency strong pulse current is increased to 100A / mm 2 ~120A / mm 2 , releasing at least 2 pulses under this high current condition.

[0015] Furthermore, the discharge voltage of the electromagnetic pulse treatment system is 15kV~20kV, and the maximum discharge energy is 150kJ~200 kJ.

[0016] Furthermore, the forming groove of the forming die is a concave arc-shaped groove, the bottom surface of the driving block is a convex arc-shaped curved surface matching the forming groove, and a grid embedding groove matching the rib plate of the grid rib wall panel workpiece is provided on the bottom surface.

[0017] Also provided is an in-situ self-resistance heating-magnetic pulse bending forming device, which uses the in-situ self-resistance heating-magnetic pulse bending forming process as described above, including a pulse power generator, an electromagnetic pulse processing system, a base, a forming die fixedly arranged on the base, edge clamping blocks arranged on both sides above the top surface of the forming die, a driving block suspended just above the forming groove of the forming die, and an electromagnetic coil arranged above the driving block, wherein electrodes are respectively arranged on the edge clamping blocks on both sides, and the electrodes on both sides are respectively connected to the two output electrodes of the pulse power generator, and the electromagnetic coil is in the shape of an equidistant spiral curve, and its two ends are respectively connected to the two discharge ends of the electromagnetic pulse processing system;

[0018] A lifting mechanism is fixedly arranged on one side of the top surface of the base, a lifting plate is fixedly connected to the top positioning output end of the lifting mechanism, the electromagnetic coil is fixedly arranged on the top surface of the lifting plate, and the driving block is movably hung on the bottom of the lifting plate;

[0019] The top front and rear sides of the base are symmetrically provided with horizontal longitudinal positioning mechanisms, and the positioning output end of the horizontal longitudinal positioning mechanism is fixedly connected with a longitudinal positioning plate. The top left and right sides of the base are symmetrically provided with horizontal transverse positioning mechanisms, and the positioning output end of the horizontal transverse positioning mechanism is fixedly connected with a transverse positioning plate.

[0020] A clamping drive mechanism is fixedly arranged on the transverse positioning plate, and a power output end of the clamping drive mechanism is fixedly connected to the edge clamping block via a connecting plate.

[0021] Furthermore, the cross-section of the electromagnetic coil is a 2mm×4mm rectangle, and the number of turns is 10.

[0022] Furthermore, the electromagnetic coil current flows to the same straight line segment to cover the area directly above the driving block.

[0023] Furthermore, the side walls on both sides of the driving block are fixedly connected with hanging ears, and a pin rod is movably inserted in the hanging ears, and the other end of the pin rod is connected to the lifting plate.

[0024] Furthermore, support rails are fixedly provided on the top surface of the base and located on the left and right sides of the forming groove, the top of the support rails is slidably connected to a support slider, and the bottom end of the clamping drive mechanism is embedded in the top surface of the support slider.

[0025] Furthermore, at least one guide column is fixedly arranged on the top surface of the base, and the lifting plate is movably sleeved on the outer side of the guide column.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. The present invention uses the synergistic effect of in-situ self-resistance heating and magnetic pulse bending to bend the titanium alloy wall panel based on the Joule thermal effect and the pure electroplastic effect, so that the titanium alloy wall panel with low conductivity, difficult to deform, and difficult to electromagnetically form has good bending formability. By superimposing the impressed current generated by the coil current and the heating current of the wall panel in the same direction, the Lorentz force is increased, thereby improving the bending forming efficiency of the titanium alloy grid rib wall panel workpiece;

[0028] 2. The present invention adopts a copper driving block of a special shape that fits the rib plate. Due to its high conductivity and high temperature resistance, it not only solves the problem of low conductivity and difficulty in electromagnetic forming of titanium alloy, but also solves the problem of easy instability of the rib plate under the instantaneous high-load and high-speed impact of electromagnetic forming. It also solves the problem of insufficient Lorentz force and low deformation efficiency caused by the small action area when the electromagnetic coil acts on the rib during electromagnetic forming;

[0029] 3. The present invention fills the cavity of the grid rib wall panel with a driving block of a special structure. The driving block plays the role of shaping the filling block to support the rib plate to prevent it from becoming unstable during deformation. Through the coupling effect of in-situ self-resistance heating and magnetic pulse bending forming, the titanium alloy grid rib wall panel can be better bent while maintaining the stability of the rib plate, achieving a better forming effect and ensuring the forming quality of the titanium alloy grid rib wall panel. Since the forming is achieved under an instantaneous large load impact, the production efficiency of the titanium alloy wall panel bending can be effectively improved, saving time and cost;

[0030] 4. The present invention clamps and fixes the two ends of the titanium alloy grid rib wall panel through edge clamping blocks, which can effectively prevent deformation of the edge area of ​​the wall panel. Electrodes are set on the edge clamping blocks to enable the wall panel to be continuously energized for self-resistance heating, thereby increasing the impact effect of the Lorentz force in electromagnetic forming, effectively solving the problem that the titanium alloy wall panel is difficult to deform. At the same time, the current gain generated by the external current of the electromagnetic coil also effectively solves the problem that the titanium alloy has low electrical conductivity and is difficult to form. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the three-dimensional structure of a grid rib wall panel workpiece that needs to be bent and formed;

[0032] Figure 2 It is a schematic diagram of the main structure of the clamping tool of the present invention;

[0033] Figure 3 It is a schematic diagram of the main structure of the mesh rib wall panel workpiece in the assembled state in the clamping fixture;

[0034] Figure 4 It is a top view structural schematic diagram of the relative position of the electromagnetic coil and the clamping fixture;

[0035] Figure 5 is a schematic diagram of the three-dimensional structure of the forming die;

[0036] Figure 6 is a schematic diagram of the three-dimensional structure of the driving block;

[0037] Figure 7 is a schematic diagram of the three-dimensional structure of the edge pressing block;

[0038] Figure 8 is a schematic diagram of the circuit structure of the pulse power generator;

[0039] Fig. 9 It is a schematic diagram of a pulse current waveform of the present invention;

[0040] Fig.10 is a schematic diagram of the circuit structure of the electromagnetic pulse processing system 7;

[0041] Fig.11This is one of the structural schematic diagrams of the in-situ self-resistance heating-magnetic pulse bending forming device of the present invention;

[0042] Fig.12 This is the second structural schematic diagram of the in-situ self-resistance heating-magnetic pulse bending forming device of the present invention;

[0043] Fig.13 It is a three-dimensional structural schematic diagram of the automatic positioning and clamping state of the grid rib wall panel workpiece;

[0044] Fig.14 is a schematic diagram of the three-dimensional structure of the lifting mechanism;

[0045] Fig.15 It is a schematic diagram of the relative positions of the pin rod and the hanging ear when the driving block and the grid rib wall panel workpiece are assembled;

[0046] Fig.16 A three-dimensional diagram of stress distribution of the grid rib wall panel workpiece after the workpiece is formed by the in-situ self-resistance heating-magnetic pulse bending forming process;

[0047] Fig.17 A top view of stress distribution of the grid rib wall panel workpiece after the grid rib wall panel workpiece is formed by the in-situ self-resistance heating-magnetic pulse bending forming process;

[0048] Fig.18 The main view of the stress distribution of the grid rib wall panel workpiece after being formed by the in-situ self-resistance heating-magnetic pulse bending forming process.

[0049] In the figure: 1. forming die; 2. edge pressing block; 3. driving block; 4. electrode; 5. electromagnetic coil; 6. pulse power generator; 7. electromagnetic pulse processing system; 701. power supply; 702. capacitor; 703. capacitor switch; 704. inductor; 705. resistor; 8. base; 9. lifting mechanism; 901. pressing plate; 902. hanging ear; 903. pin rod; 10. lifting plate; 11. horizontal longitudinal positioning mechanism; 12. longitudinal positioning plate; 13. horizontal transverse positioning mechanism; 14. transverse positioning plate; 15. cylinder mounting frame; 16. clamping driving mechanism; 17. connecting plate; 18. first cylinder bracket; 19. supporting guide rail; 20. supporting slider; 21. guide column; 22. second cylinder bracket; 100. grid rib wall panel workpiece. DETAILED DESCRIPTION

[0050] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0051] It should be noted that when a component is referred to as being "mounted on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a central component at the same time. When a component is considered to be "fixed to" another component, it may be directly fixed on the other component or there may be a central component at the same time.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.

[0053] The in-situ self-resistance heating-magnetic pulse bending forming process and device of the present invention are used for Figure 1 The mesh rib wall panel workpiece 100 is made of titanium alloy (TC4) material. Figures 2 to 7 As shown, the clamping fixture and electromagnetic coil 5 for applying the in-situ self-resistance heating-magnetic pulse bending forming process of the present invention are shown. The clamping fixture includes a forming die 1, edge clamping blocks 2 arranged on both sides of the top surface of the forming die 1, and a driving block 3 located between the two edge clamping blocks 2. When in use, the grid rib wall panel workpiece 100 to be processed is placed on the top surface of the forming die 1, with the rib plate facing upward, and its two ends are pressed tightly against the forming die 1 through the edge clamping blocks 2, effectively preventing the edge area of ​​the grid rib wall panel workpiece 100 from being deformed. The bottom surface of the edge clamping block 2 is provided with a grid embedding groove that matches the rib plates at the two ends of the grid rib wall panel workpiece 100. By embedding the grid embedding groove with the sheet metal at the corresponding position, the positioning effect of the edge area at both ends of the grid rib wall panel workpiece 100 can be further enhanced to avoid deformation of the edge area. The edge clamp block 2 is provided with electrodes 4 made of oxygen-free high-conductivity copper material, and the electrodes 4 on both sides are respectively connected to the two output electrodes of the pulse power generator, so that a pulse current can be input to both ends of the grid rib wall panel workpiece 100 through the pulse power generator 6 to make it self-resistance heated, and the grid rib wall panel workpiece 100 is bent based on the Joule heat effect and pure electroplastic effect, so that the titanium alloy wall panel with low electrical conductivity, difficult deformation and difficult electromagnetic forming can have good bending formability.

[0054] The electromagnetic coil 5 is located directly above the clamping fixture, and the current of the electromagnetic coil 5 flows in the same straight line segment on one side covering the area directly above the driving block, so that the impressed current generated by the coil current and the heating current of the wall panel are superimposed in the same direction, thereby increasing the Lorentz force and improving the bending forming efficiency of the grid rib wall panel workpiece 100. In this embodiment, a forming groove is provided at the center of the top surface of the forming die 1, and the forming groove is a concave arc-shaped groove. The driving block 3 is made of copper material, and its bottom surface is a convex arc-shaped curved surface matching the forming groove, and a grid embedding groove matching the rib plate of the grid rib wall panel workpiece 100 is provided on the bottom surface.

[0055] After the driving block 3 is suspended on the grid rib wall panel workpiece 100, the side surfaces at both ends of the driving block 3 slide and fit with the inner side surfaces of the edge pressing block 2 respectively during the falling process. Then, when the electromagnetic coil 5 is energized to generate a magnetic field, the strong Lorentz force induced by the driving block 3 causes the driving block 3 to instantly impact the grid rib wall panel workpiece 100 in a high-temperature state; during this process, the density of the pulse current passed into the inside of the grid rib wall panel workpiece 10 also increases synchronously (the pulse current adopts a programmable pulse power supply, and the current size is controllable). At this time, the wall panel is also a conductor that carries a strong current (a superposition of a weaker induced current and an introduced strong current, and the two are in the same direction at the moment of forming). The grid rib wall panel workpiece 10 is also affected by the Lorentz force in the background magnetic field (the titanium alloy material has low electrical conductivity, and the wall panel is far away from the electromagnetic coil, so the induced current and the Lorentz force are weak). The Lorentz force and the impact force of the driving block 3 are synergistically formed, and the forming force and forming effect are enhanced through the coupling effect of in-situ self-resistance heating and magnetic pulse bending forming. During the bending process of the grid rib wall panel workpiece 10, the position of the rib is in a compressive bending strain state in which the top is in a longitudinal (length direction of the wall panel) compressive stress state and the web at the bottom is in a longitudinal tensile stress state. The high rib is a thin-walled weak rigidity structure and the longitudinal unconstrained area is relatively long. It is very easy to cause unstable bending under compression conditions. Therefore, during the downward high-speed impact of the driving block 3, the grid embedding grooves arranged on the bottom surface thereof are interlocked with the grid ribs of the grid rib wall panel workpiece 10, which can strongly support the structure of the entire rib during the impact deformation process, avoid unstable bending, achieve better forming effect, and ensure the forming quality of the grid rib wall panel workpiece 100.

[0056] Compared with electromagnetic forming without a driving block 3, the high conductivity of copper can be used to increase the Lorentz force, and the geometric design of the driving block 3 can ensure that it has a large area of ​​efficient contact with the wall panel, so as to further improve the deformation efficiency and increase the action area, and solve the problems of low conductivity of titanium alloy, difficulty in electromagnetic forming, and small action area of ​​direct electromagnetic forming ribs (most of the force of the traditional electromagnetic coil 5 without a driving block 3 is on the very narrow rib area closest to the electromagnetic coil 5, and the force action efficiency is low; and the load is extremely uneven, and the deformation of the web is mainly achieved under the vertical impact force on the rib, which is very easy to cause local thinning and cracking of the web). At the same time, because the copper driving block is resistant to high temperature, its geometric shape can also fill the weak stiffness area between each rib during the impact bending deformation of the wall panel, avoiding the high ribs of the grid rib wall panel workpiece 100 from being unstable and lateral bending deformation under instantaneous high-load high-speed impact, and achieving a variety of beneficial effects.

[0057] The present invention provides an in-situ self-resistance heating-magnetic pulse bending forming process, comprising the following steps:

[0058] S1. Sample clamping: Place the grid rib wall panel workpiece 100 to be processed on the positioning table on both sides of the forming groove of the forming die 1, and fix and clamp the two ends of the grid rib wall panel workpiece 100 through the pressure block 2 in cooperation with the positioning table, with the rib plate surface of the grid rib wall panel workpiece 100 facing upward, and suspend the copper material driving block 3 directly above the grid rib wall panel workpiece 100.

[0059] Before clamping the sample, it is necessary to check the status of the equipment, such as whether the connection between the pulse power generator 6 and the electrode 4 is reliable, to ensure the reliable supply of the subsequent self-resistance heating current. At the same time, the surface of the grid rib wall panel workpiece 100, the edge clamping block 2 and the driving block 3 are treated with oil and finishing to ensure the subsequent clamping effect.

[0060] S2, self-resistance heating: start the pulse power generator 6, and pass a preset high-frequency strong pulse current into the mesh rib wall panel workpiece 100 through the electrodes on the edge clamping blocks 2 on both sides, so that the mesh rib wall panel workpiece 100 is self-resistance heated and heated to soften to the target heating temperature.

[0061] The circuit structure of the pulse power generator 6 is as follows: Figure 8 As shown in the prior art, the pulse circuit outputted by the Fig. 9 In this embodiment, the preset pulse current parameters are set as follows: steady current mode, frequency 500 Hz, duty cycle 5%, current density 10 A / mm 2 ~30A / mm 2The self-resistance heating time is set to 20 seconds, and the target heating temperature is set to 500° C. The specific parameters of the pulse current and the self-resistance heating time are determined according to the specific structure type and size specifications of the grid rib wall panel workpiece 100 and the required target heating speed.

[0062] The instantaneous temperature of the web on the mesh rib wall panel workpiece 100 is monitored and recorded by an infrared thermal imager or by spot welding thermocouples on the edge of the mesh rib wall panel workpiece 100, so as to ensure that heating is suspended after the temperature of the web on the mesh rib wall panel workpiece 100 reaches the predetermined hot working temperature.

[0063] S3, magnetic pulse bending: the electromagnetic pulse processing system 7 discharges to the electromagnetic coil 5 above the driving block 3, and the electromagnetic coil 5 generates a magnetic field, which generates a strong Lorentz force in the driving block 3, causing the driving block 3 to move at high speed and hit the straight wall panel at the bottom end of the grid rib wall panel workpiece 100, causing the straight wall panel to bend and deform until it is pressed against the forming groove of the forming die 1.

[0064] The circuit structure of the electromagnetic pulse processing system 7 is as follows: Fig.10 As shown in the prior art, the pulse circuit outputted by the Fig. 9 The electromagnetic pulse treatment system 7 includes a power supply 701, a capacitor 702, a capacitive switch 703, an inductor 704 and a resistor 705. One end electrode of the power supply 701 is connected to one end of the electromagnetic coil 5. The other end electrode of the power supply 701 is connected in series with the inductor 704 and the resistor 705 in sequence and then connected to the other end of the electromagnetic coil 5. The capacitor 702 is connected in series with the capacitive switch 703 and then connected in parallel with the two electrode ends of the power supply 701. In this embodiment, the discharge voltage of the electromagnetic pulse treatment system 7 is 15kV~20kV, the maximum discharge energy is 150kJ~200 kJ, the capacitance of the capacitor 702 is 0 μF~300 μF continuously adjustable, and the discharge voltage is 5~20kV.

[0065] While the electric self-resistance heating is in progress, the power supply 701 of the electromagnetic pulse processing system 7 is turned on, the capacitor switch 703 is turned on, the capacitor 702 starts to charge, and the current flows through the resistor 705 and the inductor 704; as time goes by, the voltage in the capacitor 702 gradually increases, and the current reaches a maximum; after the self-resistance heating reaches the target heating temperature, the capacitor switch 703 is disconnected, the capacitor 702 is discharged, and the electromagnetic field released by the electromagnetic coil 5 generates a strong Lorentz force on the copper drive block 3, which impacts the straight wall panel at the bottom end of the grid rib wall panel workpiece 100 at high speed, and is bent under the action of the arc surface at the bottom of the drive block 3. While the magnetic pulse circuit of the electromagnetic pulse processing system 7 is discharging, the current density of the high-frequency strong pulse current used for self-resistance heating is increased to 100A / mm 2, and releases 2 pulses under this high current condition. Since the edges of the grid rib wall panel workpiece 100 remain unchanged due to the pressing action of the edge clamping block 2, and the rib plate only undergoes vertical displacement under the support of the grid embedding groove of the driving block 3, the deformation coordination between the rib and the web is good, and no instability will occur.

[0066] S4, power off cooling: turn off the pulse power generator 6, and allow the bent mesh rib wall panel workpiece 100 to cool naturally to room temperature. In this process, the pulse current amplitude output by the electromagnetic pulse processing system 7 is continuously attenuated, and the corresponding Lorentz force generated in the driving block 3 is also gradually reduced accordingly, so that the mesh rib wall panel workpiece 100 after bending can be pressure-maintained and shaped.

[0067] S5, taking out the sample: turn off the electromagnetic pulse processing system 7, remove the electromagnetic coil 5, the driving block 3 and the edge holding block 2, and take out the bent mesh rib wall panel workpiece 100 from the forming die 1. Perform residual stress test, metallographic structure observation and grain size measurement on the bent mesh rib wall panel workpiece 100 to detect the forming quality.

[0068] In order to realize the rapid and automatic clamping of the grid rib wall panel workpiece 100 on the clamping tooling, the rapid assembly and separation of the driving block 3 and the grid rib wall panel workpiece 100, and the rapid lifting and lowering of the electromagnetic coil 5 and the rapid determination of its relative position with the driving block 3, the present invention also provides an in-situ self-resistance heating-magnetic pulse bending forming device, which uses the in-situ self-resistance heating-magnetic pulse bending forming process as described above.

[0069] like Figures 11 to 15 As shown, the in-situ self-resistance heating-magnetic pulse bending forming device includes a pulse power generator 6, an electromagnetic pulse processing system 7, a base 8, a forming die 1 fixedly arranged on the base 8, edge clamping blocks 2 arranged on both sides above the top surface of the forming die 1, a driving block 3 suspended just above the forming groove of the forming die 1, and an electromagnetic coil 5 arranged above the driving block 3. Electrodes 4 are respectively arranged on the edge clamping blocks 2 on both sides, and the electrodes 4 on both sides are respectively connected to the two output electrodes of the pulse power generator 6. The electromagnetic coil 5 is in the shape of an equidistant spiral curve, and its two ends are respectively connected to the two discharge ends of the electromagnetic pulse processing system 7. Among them, the specific structure of the same components and the position and connection relationship between the components are the same as above.

[0070] like Fig.13As shown, horizontal longitudinal positioning mechanisms 11 are symmetrically arranged on the front and rear sides of the top surface of the base 8, and the positioning output end of the horizontal longitudinal positioning mechanism 11 is fixedly connected to the longitudinal positioning plate 12. Horizontal transverse positioning mechanisms 13 are symmetrically arranged on the left and right sides of the top surface of the base, and the positioning output end of the horizontal transverse positioning mechanism 13 is fixedly connected to the transverse positioning plate 14. Specifically, in this embodiment, the horizontal longitudinal positioning mechanism 11 and the horizontal transverse positioning mechanism 13 both use horizontally mounted cylinders to respectively realize the forward and backward movement of the longitudinal positioning plate 12 and the transverse positioning plate 14. The cylinder is fixedly mounted on the top surface of the base 8 through a cylinder mounting frame 15. After the grid rib wall panel workpiece 100 to be processed is placed on the top of the forming die 1, the horizontal longitudinal positioning mechanisms 11 on both sides drive the longitudinal positioning plates 12 on both sides to simultaneously approach the grid rib wall panel workpiece 100 and abut against the front and rear side surfaces of the straight wall panels at the bottom end of the grid rib wall panel workpiece 100, thereby realizing the horizontal longitudinal ( Fig.13 The horizontal lateral positioning mechanism 13 on both sides then drives the lateral positioning plates 14 on both sides to approach the grid rib wall panel workpiece 100 at the same time and abut against the left and right sides of the straight wall panel at the bottom end of the grid rib wall panel workpiece 100, thereby achieving horizontal lateral ( Fig.13 In this way, the precise positioning of the grid rib wall panel workpiece 100 on the forming die 1 can be achieved quickly and accurately.

[0071] A clamping drive mechanism 16 is fixedly arranged on the transverse positioning plate 14, and the power output end of the clamping drive mechanism 16 is fixedly connected to the edge pressing block 2 through a connecting plate 17. Specifically, since the clamping drive mechanism 16 is mainly used to realize the vertical lifting of the edge pressing block 2 ( Fig.13 ), so in this embodiment, the clamping drive mechanism 16 also uses a cylinder. The cylinder is vertically arranged and passes through the transverse positioning plate 14. A vertical side plate is integrally arranged on the bottom surface of the end of the transverse positioning plate 14. An "L"-shaped first cylinder bracket 18 is fixedly connected to the top surface of the transverse positioning plate 14. The cylinder is connected to the vertical side plate and the first cylinder bracket 18 by bolts respectively. When the clamping drive mechanism 16 drives the connecting plate 17 to rise, the edge pressing block 2 moves vertically upward synchronously, thereby separating from the two end edge positions of the grid rib wall panel workpiece 100; on the contrary, when the grid rib wall panel workpiece 100 is positioned on the forming die 1, the clamping drive mechanism 16 drives the connecting plate 17 to move downward, and the edge pressing block 2 moves vertically downward synchronously, and can be pressed on the grid rib wall panel workpiece 100 after being engaged with the rib plate at the edge position of the grid rib wall panel workpiece 100 through the grid embedding groove at its bottom, so as to realize the clamping and fixing of the two end edge positions of the grid rib wall panel workpiece 100 on the forming die 1.

[0072] Preferably, support rails 19 are fixedly arranged on the top surface of the base 8 and are located on the left and right sides of the forming groove 1. The top of the support rails 19 is slidably connected with a support slider 20, and the bottom end of the clamping drive mechanism 16 is embedded in the top surface of the support slider 20. In this way, it can provide a guide for the forward and backward movement of the lateral positioning plate 14, and provide a stable support foundation for the clamping drive mechanism 16 to avoid fatigue bending at the end of the lateral positioning plate 14.

[0073] A lifting mechanism 9 is fixedly arranged on one side of the top surface of the base 8, and a lifting plate 10 is fixedly connected to the top positioning output end of the lifting mechanism 9. The electromagnetic coil 5 is fixedly arranged on the top surface of the lifting plate 10, and the driving block 3 is movably hung on the bottom of the lifting plate 10. Specifically, in this embodiment, the cross section of the electromagnetic coil is a rectangle of 2mm×4mm, and the number of turns is 10 turns. Since the lifting mechanism 9 is mainly used to realize the lifting and positioning of the driving block 3 and the electromagnetic coil 5, the lifting mechanism 9 adopts two lifting cylinders arranged on the left and right, and the lifting plate 10 is driven to rise or fall by the two lifting cylinders. The two lifting cylinders are fixedly installed on the top surface of the base 8 through the second cylinder bracket 22 respectively. A positioning strip and two positioning blocks are fixedly arranged on one side of the top surface of the lifting plate 10, so as to quickly position the electromagnetic coil 5 on the lifting plate 10, that is, the positioning strip is embedded between two adjacent coils of the straight line segment of the electromagnetic coil 5, and the two positioning blocks are respectively embedded between two adjacent coils of the arc segments at both ends of the electromagnetic coil 5. A pressing plate 901 is provided on each side of the top of the electromagnetic coil 5, and the two ends of the pressing plate 901 are respectively overlapped on the top of the straight line segments on both sides of the electromagnetic coil 5, and the middle part is fastened to the top surface of the lifting plate 10 by screws, so that the electromagnetic coil 5 is fixed on the lifting plate 10. The screws are located in the hollow position of the electromagnetic coil 5.

[0074] The side walls of the driving block 3 are fixedly connected with hanging ears 902, and the hanging ears 902 are movably inserted with pin rods 903, and the other end of the pin rods 903 is connected to the lifting plate 10. When the lifting mechanism 9 drives the lifting plate 10 to rise, the electromagnetic coil 5 rises synchronously with the lifting plate 10, and the lifting plate 10 lifts the hanging ears 902 through the pin rods 903, and then lifts the driving block 3 vertically upward. Since the two ends of the grid rib wall panel workpiece 100 are clamped by the edge pressing block 2, the driving block 3 rises and separates from the grid rib wall panel workpiece 100; when the grid rib wall panel workpiece 100 to be processed is clamped on the clamping fixture, the lifting mechanism 9 drives the lifting plate 10 to move downward, and the electromagnetic coil 5 and the driving block 3 move downward synchronously with the lifting plate 10. Due to the friction between the side of the grid groove and the side of the rib plate, the driving block 3 is vertically suspended directly above the grid rib wall panel workpiece 100. Since the grid rib wall panel workpiece 100 has been accurately positioned on the forming die 1, it can be ensured that the driving block 3 can accurately complete the process of mutual interlocking with the rib plate of the grid rib wall panel workpiece 100 during the vertical downward movement. Then the electromagnetic coil 5 follows the lifting plate 10 to move down to the lowest position. At this time, the bottom end of the pin rod 903 is located below the hanging ear 902 (the vertical distance is greater than the maximum vertical deformation of the entire bending section of the grid rib wall panel workpiece 100). The driving block 3 only has an interaction force with the grid rib wall panel workpiece 100 in the vertical direction, so it will not have any adverse effect on the subsequent driving effect of the Lorentz force.

[0075] Preferably, two guide columns 21 are fixedly provided on the top surface of the base 8, and the two ends of the front edge of the lifting plate 10 are movably mounted on the outside of the two guide columns 21, respectively, to guide the vertical lifting of the lifting plate 10 and keep the lifting plate 10 stable during the lifting process.

[0076] Depend on Figures 16 to 18 It can be seen from the stress distribution diagram shown that after the grid rib wall panel workpiece 100 of TC4 material is bent by applying the in-situ self-resistance heating-magnetic pulse bending forming process of the present invention, the overall equivalent strain distribution is relatively uniform, the strain in the edge area is smaller than that in the central area, the wall panel is in good forming condition and the rib panel does not show serious instability, indicating that under the synergistic effect of the specially designed electromagnetic coil-driving block-edge clamping block tooling, the grid rib wall panel workpiece 100 of TC4 material is extremely successfully press-bent, verifying the rationality of the process system design.

[0077] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An in-situ self-resistance heating-magnetic pulse bending forming process, characterized in that: The following steps are involved: S1. Sample clamping: Place the grid rib wall panel workpiece to be processed on the positioning table on both sides of the forming groove of the forming die, and fix and clamp the two ends of the grid rib wall panel workpiece by cooperating with the positioning table through the edge pressing block, the rib plate surface of the grid rib wall panel workpiece faces upward, and suspend the copper material driving block directly above the grid rib wall panel workpiece; The forming groove of the forming die is a concave arc-shaped groove, the bottom surface of the driving block is a convex arc-shaped curved surface matching the forming groove, and a grid embedding groove matching the rib plate of the grid rib wall panel workpiece is provided on the bottom surface; S2, self-resistance heating: start the pulse power generator, and pass a preset high-frequency strong pulse current into the grid rib wall panel workpiece through the electrodes on the edge clamping blocks on both sides, so that the grid rib wall panel workpiece is self-resistance heated and heated to the target heating temperature; The preset high-frequency strong pulse current parameters are set as: steady current mode, frequency 500Hz, pulse width 100Hz, duty cycle 5%, current density 10A / mm 2 ~30A / mm 2 , the self-resistance heating time is set to 10s~30s, and the target heating temperature is set to 500℃~700℃; S3, magnetic pulse bending: the electromagnetic pulse processing system discharges the electromagnetic coil above the driving block, the electromagnetic coil generates a magnetic field, and a strong Lorentz force is generated in the driving block, so that the driving block moves at a high speed and hits the straight wall plate at the bottom end of the grid rib wall plate workpiece, so that the straight wall plate is bent and deformed until it is pressed against the forming groove of the forming die; While the magnetic pulse circuit of the electromagnetic pulse treatment system is discharging, the current density of the high-frequency strong pulse current is increased to 100A / mm 2 ~120A / mm 2 , and release at least 2 pulses; S4, power off cooling: turn off the pulse power generator to allow the bent mesh rib wall panel workpiece to cool naturally to room temperature; S5. Take out the sample: turn off the electromagnetic pulse processing system, remove the electromagnetic coil, the driving block and the edge pressing block, and take out the bent mesh rib wall panel workpiece from the forming die.

2. The in-situ self-resistance heating-magnetic pulse bending forming process according to claim 1, characterized in that: The discharge voltage of the electromagnetic pulse treatment system is 15kV~20kV, and the maximum discharge energy is 150kJ~200kJ.

3. An in-situ self-resistance heating-magnetic pulse bending forming device, using the in-situ self-resistance heating-magnetic pulse bending forming process as claimed in claim 1 or 2, characterized in that: It includes a pulse power generator, an electromagnetic pulse processing system, a base, a forming die fixedly arranged on the base, edge pressing blocks arranged on both sides above the top surface of the forming die, a driving block suspended just above the forming groove of the forming die, and an electromagnetic coil arranged above the driving block, wherein electrodes are respectively arranged on the edge pressing blocks on both sides, and the electrodes on both sides are respectively connected to the two output electrodes of the pulse power generator, and the electromagnetic coil is in the shape of an equidistant spiral curve, and its two ends are respectively connected to the two discharge ends of the electromagnetic pulse processing system; A lifting mechanism is fixedly arranged on one side of the top surface of the base, a lifting plate is fixedly connected to the top positioning output end of the lifting mechanism, the electromagnetic coil is fixedly arranged on the top surface of the lifting plate, and the driving block is movably hung on the bottom of the lifting plate; The top front and rear sides of the base are symmetrically provided with horizontal longitudinal positioning mechanisms, and the positioning output end of the horizontal longitudinal positioning mechanism is fixedly connected with a longitudinal positioning plate. The top left and right sides of the base are symmetrically provided with horizontal transverse positioning mechanisms, and the positioning output end of the horizontal transverse positioning mechanism is fixedly connected with a transverse positioning plate. A clamping drive mechanism is fixedly arranged on the transverse positioning plate, and a power output end of the clamping drive mechanism is fixedly connected to the edge clamping block via a connecting plate.

4. The in-situ self-resistance heating-magnetic pulse bending forming device according to claim 3, characterized in that: The cross section of the electromagnetic coil is a 2mm×4mm rectangle, and the number of turns is 10.

5. The in-situ self-resistance heating-magnetic pulse bending forming device according to claim 3 or 4, characterized in that: The electromagnetic coil current flows to the same straight line segment, covering the area directly above the driving block.

6. The in-situ self-resistance heating-magnetic pulse bending forming device according to claim 3, characterized in that: The side walls on both sides of the driving block are fixedly connected with hanging ears, and a pin rod is movably inserted in the hanging ears, and the other end of the pin rod is connected to the lifting plate.

7. The in-situ self-resistance heating-magnetic pulse bending forming device according to claim 3, characterized in that: The top surface of the base is fixedly provided with support rails located on the left and right sides of the forming groove, the top of the support rails is slidably connected with a support slider, and the bottom end of the clamping drive mechanism is embedded in the top surface of the support slider.

8. The in-situ self-resistance heating-magnetic pulse bending forming device according to claim 3, 6 or 7, characterized in that: At least one guide column is fixedly arranged on the top surface of the base, and the lifting plate is movably sleeved on the outer side of the guide column.

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