CN110681760B - Electromagnetic pulse hole flanging forming device for thick plate or thick arc-shaped part - Google Patents
Electromagnetic pulse hole flanging forming device for thick plate or thick arc-shaped part Download PDFInfo
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- CN110681760B CN110681760B CN201910932435.2A CN201910932435A CN110681760B CN 110681760 B CN110681760 B CN 110681760B CN 201910932435 A CN201910932435 A CN 201910932435A CN 110681760 B CN110681760 B CN 110681760B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
- B21D26/14—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces applying magnetic forces
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D19/00—Flanging or other edge treatment, e.g. of tubes
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Abstract
The invention belongs to the field of plastic forming of materials, and discloses an electromagnetic pulse hole flanging forming device for a thick plate part or a thick arc-shaped part, wherein the forming device for the thick plate part comprises a coil and a magnetic collector (103) positioned on one side of the coil, and the magnetic collector (103) is disc-shaped and is provided with two disc surfaces with different surface areas; recording a surface A with a larger surface area and a surface B with a smaller surface area, wherein the surface A is closer to the coil, and the surface B is used for being closer to a workpiece to be formed; the area difference is utilized to generate larger current density at one end of the magnetic collector (103) close to the surface B, so that the workpiece to be formed is subjected to larger electromagnetic force, and the electromagnetic pulse hole flanging forming is facilitated. According to the invention, through improving the overall structure design and the like of the device, the magnetic collectors are additionally arranged between the coils and the plate, and the multi-layer coils are matched, especially through the design of the A surfaces and the B surfaces of the magnetic collectors with surface area difference, the electromagnetic force is concentrated in the forming area corresponding to the B surface of the magnetic collector, and a good forming effect can be achieved.
Description
Technical Field
The invention belongs to the technical field of plastic forming of materials, and particularly relates to an electromagnetic pulse hole flanging forming device for a thick plate part or a thick arc-shaped part.
Background
In order to meet the requirements of light structure and light material weight, energy consumption and environmental pollution are reduced, and aluminum alloys with low density and high specific strength are increasingly applied to the fields of automobiles and aerospace. However, the aluminum alloy has the problems of low forming limit, severe rebound and the like, and the development of the aluminum alloy is severely restricted. Electromagnetic forming is a forming processing method which utilizes Lorentz force to enable metal materials to generate high-speed plastic deformation, the method can improve the forming limit of the materials, effectively reduces rebound, the formed workpiece has smaller residual stress, the workpiece has higher surface quality, and the method has wide prospect in the aspect of forming aluminum alloy. And the electromagnetic forming tool is simple, a large platform is not needed for positioning, only the forming coil and the female die are needed to be fixed in a forming area, and the position of the coil is flexibly adjusted.
In the field of aerospace, a plurality of large parts need to be formed, and when the large parts are manufactured by adopting the traditional process, higher requirements are put forward on a tool platform, a die and equipment; and some parts need to form local features to realize specific functions, and the difficulty is extremely high. Compared with the traditional method, the electromagnetic forming has great advantages in the field of aerospace, not only can improve the production efficiency, but also can obtain a workpiece with higher precision and better quality; while local features can be shaped with the flexibility of coil fabrication.
In the electromagnetic forming, pulse current is supplied to the coil, instantaneous current with a certain depth is generated on the plate under the action of electromagnetic induction, a magnetic field generated by the current on the plate and a magnetic field generated by the current in the coil repel each other, and when the repulsive force exceeds the yield strength of the material, the plate deforms. The depth of the current formed on the sheet becomes the skin depth, which is the electromagnetic volume force action area. The skin depth is related to the material resistivity, the material permeability, and the discharge frequency.
In formula (1), d: skin depth; ρ: electrical resistivity; μ: magnetic conductivity; f: the discharge frequency.
In the electromagnetic forming process, the plate rapidly obtains high movement speed in a short time, and most of plastic deformation is caused by the inertia effect under high-speed movement. Now, better effects can be achieved already when electromagnetic forming is used for flanging thin plates. The thickness of the plate is increased, the forming difficulty is improved, and the main reason is that the non-electromagnetic volume force action area is increased, the relative proportion of the receptor volume force action area is reduced, and the electromagnetic volume force effect is weakened. In the case of increasing the thickness of the sheet, in order to achieve an ideal forming effect, the skin depth in the electromagnetic forming process needs to be increased. As can be seen from equation (1), increasing the skin depth requires decreasing the discharge frequency without changing the material. From the equation (2), it can be known that the discharge frequency can be reduced by controlling the inductance to be constant and increasing the capacitance, but the discharge energy can be increased sharply, and the energy and the reaction force to be born by the coil in the discharge process are larger.
In formula (2), f: a discharge frequency; c: a capacitor; l: an inductance.
Due to the limitation of the manufacturing process, when the coil used at present is discharged at high energy, under the combined action of force and heat, epoxy resin fails, so that the structural strength of the coil is reduced rapidly, short circuit is caused when leads are extruded with each other, and the coil cannot be reused after primary discharge. There are two approaches to solving this problem: firstly, a material with better performance is adopted to replace a copper wire to wind a coil; and secondly, the structural design of the coil is optimized, and the strength of the coil is improved. Before new ideal materials come out, more structural studies have been carried out.
The cross-sectional shape of the formed coil used for electromagnetic forming is circular or rectangular, and researches show that: the cross-sectional area of the formed coil severely affects the forming ability and the service life of the coil. When the sectional area of the coil is small, the electromagnetic force generated by the coil can be better concentrated in a forming area, the forming effect is good, but due to the limitation of the existing manufacturing process, the structural strength of the coil is low when the coil is densely wound, and the service life of the coil is short. Particularly for electromagnetic pulse hole flanging forming of thick plates (such as plates with the thickness of 7-8 mm) due to the fact that the plate is thick, large voltage is needed during forming, and a coil is easy to damage due to large impact load during forming; if a coil with a large turn-to-turn pitch is adopted, the strength of the coil structure is greatly improved, but electromagnetic force is not concentrated, and an ideal forming effect cannot be achieved.
In order to ensure that the projection area of the coil corresponds to a plate forming area so as to ensure that electromagnetic force is well distributed, when a small area is formed, the existing process mostly adopts close winding, namely winding with small turn pitch, and when the thickness of a plate is small, low-voltage discharge can ensure the service life of the coil; when the thickness of the plate is increased to a certain value, the required forming force is increased, and larger discharge energy is needed, so that the coil is easy to lose effectiveness under the combined action of force and heat, and even the coil needs to be replaced by a new coil after once discharge, thereby increasing the cost of the coil and prolonging the manufacturing period of the product.
Disclosure of Invention
In view of the above defects or improvement requirements of the prior art, an object of the present invention is to provide an electromagnetic pulse hole flanging forming device for thick plates or thick arc-shaped members, which improves the overall structure design of the device, adds a magnetic collector between a coil and a plate, and matches with a multilayer coil, and particularly, by designing a surface a and a surface B of the magnetic collector with a surface area difference (wherein the surface area of the surface a is larger, and the surface area of the surface B is smaller), the induced current density near the surface B is larger than that near the surface a, and the electromagnetic force near the surface B is also larger, so that the electromagnetic force is concentrated in a forming area corresponding to the surface B of the magnetic collector, and a good forming effect can be achieved. The invention solves the problem that the current electromagnetic forming coil can not bear the high-voltage and high-energy discharge condition, and leads the application of electromagnetic forming in hole flanging of thick plate parts to be more mature. And based on the invention, the used coil can bear large voltage and ensure the forming effect of discharge forming on a small area, and the invention can keep larger turn pitch design by arranging the magnetic collector matched coil with a specific surface area shape, thereby not only improving the strength of the coil and ensuring the service life of the coil, but also concentrating the electromagnetic force in the forming area and achieving better forming effect.
In order to achieve the above object, according to one aspect of the present invention, there is provided an electromagnetic pulse hole flanging forming device for a thick plate, comprising a coil and a magnetic collector (103) located on one side of the coil, wherein the magnetic collector (103) is disc-shaped and has two upper and lower disc surfaces with different surface areas, the two upper and lower disc surfaces are plane-shaped, the center of the disc of the magnetic collector (103) is provided with a through hole, and a slit located on one side of a central axis of the disc is communicated with the through hole so that magnetic collector areas on two sides of the slit are completely isolated by the slit;
the coil is a single-layer coil or a multi-layer coil; when the coil is a single-layer coil, the single-layer coil is formed by arranging metal wires (101) around the central axis of the disc in an internal-external distribution manner in the same plane, and the plane is parallel to the upper surface and the lower surface of the magnetic collector (103); when the coils are multilayer coils, any layer of coils in the multilayer coils are arranged inside and outside in the same plane by metal wires (101) around the central axis of the disc, and the plane of each layer of coils is parallel to the upper surface and the lower surface of the magnetic collector (103);
recording the surface with larger surface area of the magnetic collector (103) as an A surface and the surface with smaller surface area as a B surface, wherein the A surface is closer to the coil than the B surface, the B surface is used for being close to a workpiece to be formed, and the coil and the magnetic collector (103) are connected and integrated into a whole through insulating resin; when alternating current is applied to the coil, induced current generated by the coil on the surface A flows to the surface B through the slit, and by utilizing the area difference between the surface A and the surface B, a larger current density is generated at one end of the magnetic collector (103) close to the surface B, so that a workpiece to be formed is subjected to a larger electromagnetic force, and the electromagnetic pulse hole flanging forming is facilitated.
As a further preference of the invention, the cross-sectional shape of the metal wire (101) is rectangular, and the turn pitch is between 2mm and 5 mm; when the coil is a multilayer coil, the layer spacing is between 2mm and 4 mm.
As a further preferred aspect of the present invention, the coil is a 3-layer coil; the metal wire (101) is a red copper wire.
As a further preferable mode of the present invention, a bolt hole is further formed in the winding center of the multilayer coil, and one end of the bolt hole is communicated with the disk center through hole of the magnetic collector (103); fastening bolts are arranged in the bolt holes and used for enhancing the strength of the integral structure after the coil and the magnetic collector (103) are integrated; and the surface of the fastening bolt is also subjected to an insulation treatment.
In a further preferred embodiment of the present invention, chromium zirconium copper is used for the magnetic collector (103).
As a further preferred aspect of the present invention, the thickness of the magnetic collector (103) is twice the skin depth.
As a further preference of the present invention, the ratio of the diameter of the a face to the B face is not more than 2, preferably equal to 2.
In a further preferred embodiment of the present invention, the insulating resin is an epoxy resin (105).
As a further preferred aspect of the present invention, the workpiece to be formed is a plate to be formed; preferably, the plate to be formed is an aluminum alloy thick plate to be formed and with the thickness of 7-8 mm.
According to one aspect of the invention, the electromagnetic pulse hole flanging forming device for the thick arc-shaped piece is characterized by comprising a coil and a magnetic collector (103) positioned on one side of the coil, wherein the magnetic collector (103) is in a disc shape and is provided with an upper disc surface and a lower disc surface which are different in surface area from each other, the surface with the larger surface area is in a plane shape, and the surface with the smaller surface area is in an arc shape; a through hole is formed in the center of a disc of the magnetic collector (103), and a slit positioned on one side of the central axis of the disc is communicated with the through hole, so that the magnetic collector areas on two sides of the slit are completely isolated by the slit;
the coil is a single-layer coil or a multi-layer coil; when the coil is a single-layer coil, the single-layer coil is formed by arranging metal wires (101) around the central axis of the disc in an internal-external distribution manner in the same plane, and the plane is parallel to the surface with larger surface area in the magnetic collector (103); when the coils are multilayer coils, any layer of coils in the multilayer coils are arranged inside and outside in the same plane by metal wires (101) around the central axis of the disc, and the plane of each layer of coils is parallel to the surface with larger surface area in the magnetic collector (103);
recording the surface with larger surface area of the magnetic collector (103) as an A surface and the surface with smaller surface area as a B surface, wherein the A surface is closer to the coil than the B surface, the B surface is used for being close to a workpiece to be formed, and the coil and the magnetic collector (103) are connected and integrated into a whole through insulating resin; when alternating current is applied to the coil, induced current generated by the coil on the surface A flows to the surface B through the slit, and by utilizing the area difference between the surface A and the surface B, a larger current density is generated at one end of the magnetic collector (103) close to the surface B, so that a workpiece to be formed is subjected to a larger electromagnetic force, and the electromagnetic pulse hole flanging forming is facilitated.
By the technical scheme, compared with the prior art, the electromagnetic pulse hole flanging forming device for the thick plate can obtain the following beneficial effects:
1) according to the invention, the magnetic collectors with different sizes of the upper surface area and the lower surface area of the disc are added between the coil and the plate, so that the forming of a small area by a large coil is realized, the device is particularly suitable for an electromagnetic pulse hole flanging forming device of a thick plate (such as an aluminum alloy thick plate with the thickness of 7-8 mm), and the defect of insufficient forming force can be overcome. The A surface (i.e. the surface with larger surface area) of the magnetic collector is close to the coil, and the B surface (i.e. the surface with smaller surface area) is close to the work to be formed (such as the plate to be formed). Induced current generated by the coil on the magnetic collector is concentrated on the surface B, and induced current is generated in a plate forming area, so that the aim of concentrating electromagnetic force is fulfilled. Compared with the problems of difficult processing, high cost, short service life and the like of the coil, the regional distribution of electromagnetic force can be changed by further replacing the magnetic collectors (the upper surface area, the lower surface area and the thickness) with different shapes so as to realize the deformation of different forming regions, and the method is simpler and more convenient. The thickness of the magnetic collector is preferably twice of the skin depth, so that the current of the A surface and the B surface can be effectively prevented from being reversely offset. The larger the ratio of the surface areas of the A surface and the B surface of the magnetic concentrator is, the more energy is concentrated on a smaller area, so that the area obtains larger magnetic field intensity and electromagnetic force, and the forming is more facilitated. The ratio of the surface areas of the A surface and the B surface of the magnetic collector is preferably not more than 4 (the surface area of the A surface is larger than the surface area of the B surface), namely, the ratio of the diameters of the A surface and the B surface is not more than 2, the ratio of the diameters of the A surface and the B surface of the magnetic collector is called the relative diameter of the magnetic collector, the maximum value of the electromagnetic force is increased along with the increase of the relative diameter, but the increase degree is smaller, generally, the amplitude of the electromagnetic force is slow after the relative diameter reaches 2, and the ratio of the diameters of the A surface and the B surface (namely, the relative diameter) is preferably equal to 2.
2) The coil structure is optimized, and particularly, a multilayer coil can be adopted, so that the coil structure not only ensures higher strength, but also can bear huge reaction force during forming (the more the number of layers of the coil is, the larger forming force can be provided), the size of electromagnetic forming force can be further improved by matching with the magnetic collector assembly, and the requirement on the size of the electromagnetic force during forming of a thick plate is met. The invention preferably adopts multilayer coils, and can also obtain good die attaching effect when the hole flanging is carried out on the thick plate.
3) Based on the invention, the used coil can bear large voltage and ensure the forming effect of discharge forming on a small area, thereby ensuring the ideal forming effect, ensuring the service life of the coil, reducing the cost and shortening the manufacturing period. When traditional coil design, in order to guarantee the shaping effect, the projected area of coil corresponds with sheet metal shaping region, when little regional shaping, in order to reach the required huge power of thick shaping of board, the coil can only adopt the mode of multiturn close winding, there can powerful interact power between circle and the circle, and the current density in the unit area is very big, the heat effect of electric current makes when discharging, the temperature rise of coil is very big, carbonize epoxy even, the wire rod contacts the short circuit after extrudeing each other, lead to the coil to damage. Due to the existence of the magnetic collector, the matching of the surface B of the magnetic collector and a small area to be formed can be realized by utilizing the further design of the surface of the magnetic collector, the arrangement mode of multi-turn close winding of the coil is avoided, the coil structure is optimized, the structural strength is higher, the service life of the coil is prolonged, and the problem of high cost caused by the damage of the current coil is solved.
The invention can adopt red copper wire to wind the coil structure, the turn pitch is preferably controlled to be 2mm to 5mm, besides the turn pitch, the invention also controls the section shape of the coil structure to be rectangular, and the coil with the rectangular lead section enables the plate material to be deformed more uniformly compared with the coil with the circular lead section. In addition, when a multilayer coil is used, the present invention is also achieved by preferably controlling the interlayer distance of the multilayer coil structure to 2mm to 4 mm; the layer spacing is too small, so that the concentration of the wires can be caused, the action of heat and force generated during electrifying can be relatively concentrated due to the heat effect of current and the mutual repulsive force among the wires, the structural strength and the service life of the coil can be influenced, and the action of electromagnetic force can be weakened due to the increase of the spacing; thus, the selection of a suitable layer spacing ensures both sufficient structural strength of the coil and sufficient electromagnetic force during the forming process.
The magnetic collector has the function of concentrating electromagnetic force to a small forming area through the upper and lower area difference, and the coil can adopt a coil with larger turn pitch; compared with a close-wound coil, under the condition of the same number of turns, the turn-to-turn distance of the coil is increased, and the peak value of the electromagnetic force is reduced; the invention utilizes the cooperation of the multilayer coil and the magnetic collector to avoid the adverse phenomenon (the feasibility of the method is also verified through subsequent finite element numerical simulation). The invention can preferably adopt three layers of coils, each layer of coil preferably adopts larger turn pitch (the turn pitch is preferably between 2mm and 5 mm) when being wound, because the turn pitch is enlarged, the current density in unit area in the coil is reduced, and when the coil is electrified, the heat has enough space diffusion; and on the other hand, the space between the wires is filled with the epoxy resin with enough thickness, so that mutual extrusion of the wires is restrained, high-energy multiple discharge can be borne finally, the service life of the coil is prolonged, the loss of the coil is reduced, the coil can be recycled, and the cost is effectively reduced.
The above analysis is taken as an example of an electromagnetic pulse hole flanging forming device for a thick plate (in which a used magnetic collector has an upper and a lower planar disk surfaces), when a workpiece to be formed is an arc-shaped part, especially a thick arc-shaped part, the lower surface with a smaller area in the magnetic collector can be designed into a curved surface (i.e. an arc surface shape) which is in accordance with the curved surface characteristics of a plate, and accordingly, the electromagnetic pulse hole flanging forming device for the thick arc-shaped part can be obtained; other structures (such as coils and the like) in the electromagnetic pulse hole flanging forming device for the thick arc-shaped part can be set similarly to the electromagnetic pulse hole flanging forming device for the thick plate part, and similar beneficial effects are achieved.
Drawings
Fig. 1 is a structural schematic diagram of a magnetic concentrator in an electromagnetic pulse hole flanging forming device for thick plates.
Fig. 2 is a schematic diagram of relative positions of a coil and a magnetic collector in an electromagnetic pulse hole flanging forming device for thick plates.
Fig. 3 is a schematic diagram of a coil in an electromagnetic pulse hole flanging and forming device for thick plate parts.
Fig. 4 is a schematic diagram of relative positions of components in an electromagnetic pulse hole flanging forming device for thick plate parts.
Fig. 5 is a schematic tool diagram of an electromagnetic pulse hole flanging forming device for thick plate parts.
Fig. 6 is a circuit diagram showing a connection between the electromagnetic forming machine and the pulse discharge circuit.
Fig. 7 is a schematic view of a tooling of an electromagnetic pulse hole flanging and forming device for thick arc-shaped parts, wherein the magnetic collector parts have arc-shaped lower surfaces.
The meanings of the reference symbols in the figures are as follows: 1 is the whole subassembly that coil and magnetic collector formed, 2 is the blank holder, 3 is the sheet material, 4 is the mould, 5 is the switch, 6 is the resistance, 7 is the electric capacity, 101 is the metal wire (corresponding to metal coil), 102 is fastening bolt, 103 is the magnetic collector, 104 is the gasket, 105 is epoxy.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The forming device in the invention, namely, the electromagnetic hole flanging forming device, comprises a pulse discharge circuit, a forming coil, a female die, a blank holder and a plate material as shown in figure 5. The coil system comprises three layers of flat spiral coils and a magnetic collector, wherein the three layers of flat spiral coils are connected in series (namely, the coils are in the form of longitudinal three layers of concentric coils and are connected in series, so that the requirements of force and energy during forming can be met), and the magnetic collector is arranged below the flat coils, is not in contact with the coils and is insulated and separated by epoxy resin (namely, the coils and the magnetic collector are integrated together, and gaps between the coils are filled with epoxy resin).
The magnetic collector is in a disc shape as shown in fig. 1, and has an upper disc surface and a lower disc surface with different surface areas, a through hole is arranged at the center of the disc of the magnetic collector, and a slit positioned on one side of a central axis of the disc is communicated with the through hole to completely isolate magnetic collector areas on two sides of the slit by the slit. The magnetic collector has the function of concentrating the electromagnetic force to a small forming area through the upper and lower area difference. The slit is filled with epoxy resin after machining, and the magnetic collector slit functions to flow induced current from the upper surface to the lower surface.
The coil can further comprise a fastening bolt, so that the strength of the coil is further enhanced, and the service life is prolonged. That is to say, in order to guarantee that the whole has higher structural strength, can withstand huge reaction force in the forming process, can add the bolt fastening in the hole between coil and magnetic collector, the bolt surface carries out insulating treatment (for example, the bolt can be wrapped up with insulating paper, guarantees to have good insulation with coil and magnetic collector).
Further, the bolt 102 and washer 104 shown in FIG. 3 are wrapped in epoxy with an upper nut to adjust tightness.
As shown in fig. 5, the sheet is placed above the female die, the region to be formed on the sheet is pressed, and then the forming coil is pressed on the pressing ring. In the practical experiment process, a pressure machine can be used for applying pressure to the surface A of the coil (the surface A and the surface B of the coil are named in a mode that the surface A of the coil, the surface B of the coil, the surface A of the magnetic collector and the surface B of the magnetic collector are sequentially arranged by taking the surface A of the coil and the surface B of the magnetic collector as reference), the pressure is required to meet the requirement of blank holder force, and the reaction force of the plate material on the coil in the forming process can be sufficiently resisted.
The coil 1 is connected with a switch 5, a protective resistor 6 and an energy storage capacitor 7 in sequence. The other end of the electromagnetic forming machine 9 is connected with the switch 5, the protective resistor 6 and the energy storage capacitor 7 through the switch 8. Electrical parameters meeting the conditions are set according to the energy required to form the workpiece. The invention is suitable for hole flanging of thick plates, and an electromagnetic forming machine capable of providing enough voltage and energy is required when the hole flanging device is used.
The switches 8 and 5 are closed, the electromagnetic forming machine charges the capacitor 7, after the capacitor is fully charged, the switch 8 is opened, and the capacitor 7 discharges the coil 1.
Further, the pulse current in the three-layer flat spiral coil connected in series generates an induced current on the upper surface of the lower magnetic collector.
Further, the induced current generated by the coil at the large-area end of the magnetic collector can flow to the lower surface, and the current density of the lower surface of the magnetic collector is larger than that of the upper surface due to the area difference of the upper surface and the lower surface, so that larger induced current is generated on the plate, and the plate is formed by the electromagnetic repulsive force.
The coil is encapsulated with an epoxy board. The experimental results prove that after the coil is damaged, the wire in the central area is broken and even burst out under the comprehensive action of force, so that the wire in the central area is preferably restrained by the fastening bolt 102 and the gasket 104, and a better fastening effect is achieved. In fig. 3, the gap parts between the parts are filled with epoxy resin, so that good insulation between the metal parts is ensured.
The embodiment shown in the invention is the flanging of the inclined hole, the forming difficulty of the acute angle side of the female die is higher, and the electromagnetic force at the slit of the magnetic collector is found to be lower in experiments and simulations (as shown in figure 1, the magnetic collector is provided with a slit in the longitudinal direction) and belongs to a weak area.
The above embodiment is an example of a 3-layer coil, and the coil may be a single-layer coil or other multi-layer coil; the winding modes of the multilayer coil and the single-layer coil are the same, and the multilayer coil is formed by winding a copper wire in series after the single-layer coil is wound in one layer.
The embodiment shown in the invention is a flat plate, if the plate has a curved surface characteristic (namely, when the plate is an arc-shaped piece), the lower surface of the magnetic collector can be designed into a curved surface which is in accordance with the curved surface characteristic of the plate, so that the electromagnetic pulse hole flanging forming device for the thick arc-shaped piece is obtained; other structures (including shape parameters of each structure and the like) in the electromagnetic pulse hole flanging forming device for the thick arc-shaped part can be arranged similarly to the electromagnetic pulse hole flanging forming device for the thick plate part, as shown in fig. 7. For example, when the workpiece to be formed has a cambered surface characteristic, the lower surface of the structure of the magnetic collector in the electromagnetic pulse hole flanging forming device can be processed into a cambered surface shape, so that a proper distance is ensured between the workpiece and the magnetic collector.
In the invention, the magnetic collector can preferably adopt any one of chromium, zirconium and copper in the prior art, has better conductivity and higher strength. In addition, the invention can adopt red copper to wind and form the coil. Because red copper is softer, before the coiling into coil, can refer to prior art and carry out work hardening to red copper, improve the intensity of wire rod.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. An electromagnetic pulse hole flanging forming device for thick plates is characterized by comprising a coil and a magnetic collector (103) positioned on one side of the coil, wherein the magnetic collector (103) is disc-shaped and is provided with an upper disc surface and a lower disc surface which are different in surface area, the upper disc surface and the lower disc surface are plane-shaped, the center of the disc of the magnetic collector (103) is provided with a through hole, and a slit positioned on one side of the central axis of the disc is communicated with the through hole so that the magnetic collector areas on two sides of the slit are completely isolated by the slit;
the coil is a single-layer coil or a multi-layer coil; when the coil is a single-layer coil, the single-layer coil is formed by arranging metal wires (101) around the central axis of the disc in an internal-external distribution manner in the same plane, and the plane is parallel to the upper surface and the lower surface of the magnetic collector (103); when the coils are multilayer coils, any layer of coils in the multilayer coils are arranged inside and outside in the same plane by metal wires (101) around the central axis of the disc, and the plane of each layer of coils is parallel to the upper surface and the lower surface of the magnetic collector (103);
recording the surface with larger surface area of the magnetic collector (103) as an A surface and the surface with smaller surface area as a B surface, wherein the A surface is closer to the coil than the B surface, the B surface is used for being close to a workpiece to be formed, and the coil and the magnetic collector (103) are connected and integrated into a whole through insulating resin; when alternating current is applied to the coil, induced current generated by the coil on the surface A flows to the surface B through the slit, and a larger current density is generated at one end of the magnetic collector (103) close to the surface B by utilizing the area difference of the surface A and the surface B, so that a workpiece to be formed is subjected to a larger electromagnetic force, and the electromagnetic pulse hole flanging forming is facilitated;
and the turn-to-turn pitch of the metal wire (101) is between 2mm and 5 mm; when the coil is a multilayer coil, the interlayer distance is 2mm to 4 mm; a bolt hole is further formed in the winding center of the multilayer coil, and one end of the bolt hole is communicated with a disc center through hole of the magnetic collector (103); fastening bolts are arranged in the bolt holes and used for enhancing the strength of the integral structure after the coil and the magnetic collector (103) are integrated; and the surface of the fastening bolt is also subjected to an insulation treatment.
2. The electromagnetic pulse hole flanging forming device for thick plates of claim 1, characterized in that the cross-sectional shape of said metal wire (101) is rectangular.
3. The electromagnetic pulse hole flanging forming device for thick plates of claim 1, wherein said coil is a 3-layer coil; the metal wire (101) is a red copper wire.
4. The electromagnetic pulse hole flanging forming device for thick plates according to claim 1, characterized in that the magnetic collectors (103) are made of chromium zirconium copper.
5. The electromagnetic pulse hole flanging forming device for thick plate members as claimed in claim 1, wherein said magnetic collector (103) has a thickness twice the skin depth.
6. The electromagnetic pulse hole flanging apparatus for thick plate members as claimed in claim 1, wherein the ratio of the diameter of said a-side to said B-side is not more than 2.
7. The electromagnetic pulse hole flanging apparatus for thick plate members as claimed in claim 6, wherein the ratio of the diameter of said a-side to said B-side is equal to 2.
8. The electromagnetic pulse hole flanging molding apparatus for thick plate members as claimed in claim 1, wherein said insulating resin is an epoxy resin (105).
9. The electromagnetic pulse hole flanging forming device for thick plates of claim 1, wherein said workpiece to be formed is a plate to be formed; the plate to be formed is an aluminum alloy thick plate to be formed, and the thickness of the aluminum alloy thick plate is 7-8 mm.
10. An electromagnetic pulse hole flanging forming device for a thick arc-shaped piece is characterized by comprising a coil and a magnetic collector (103) positioned on one side of the coil, wherein the magnetic collector (103) is disc-shaped and is provided with an upper disc surface and a lower disc surface which have different surface areas, the surface with the larger surface area is plane-shaped, and the surface with the smaller surface area is arc-shaped; a through hole is formed in the center of a disc of the magnetic collector (103), and a slit positioned on one side of the central axis of the disc is communicated with the through hole, so that the magnetic collector areas on two sides of the slit are completely isolated by the slit;
the coil is a single-layer coil or a multi-layer coil; when the coil is a single-layer coil, the single-layer coil is formed by arranging metal wires (101) around the central axis of the disc in an internal-external distribution manner in the same plane, and the plane is parallel to the surface with larger surface area in the magnetic collector (103); when the coils are multilayer coils, any layer of coils in the multilayer coils are arranged inside and outside in the same plane by metal wires (101) around the central axis of the disc, and the plane of each layer of coils is parallel to the surface with larger surface area in the magnetic collector (103);
recording the surface with larger surface area of the magnetic collector (103) as an A surface and the surface with smaller surface area as a B surface, wherein the A surface is closer to the coil than the B surface, the B surface is used for being close to a workpiece to be formed, and the coil and the magnetic collector (103) are connected and integrated into a whole through insulating resin; when alternating current is applied to the coil, induced current generated by the coil on the surface A flows to the surface B through the slit, and a larger current density is generated at one end of the magnetic collector (103) close to the surface B by utilizing the area difference of the surface A and the surface B, so that a workpiece to be formed is subjected to a larger electromagnetic force, and the electromagnetic pulse hole flanging forming is facilitated;
and the turn-to-turn pitch of the metal wire (101) is between 2mm and 5 mm; when the coil is a multilayer coil, the interlayer distance is 2mm to 4 mm; a bolt hole is further formed in the winding center of the multilayer coil, and one end of the bolt hole is communicated with a disc center through hole of the magnetic collector (103); fastening bolts are arranged in the bolt holes and used for enhancing the strength of the integral structure after the coil and the magnetic collector (103) are integrated; and the surface of the fastening bolt is also subjected to an insulation treatment.
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| CN201910932435.2A CN110681760B (en) | 2019-09-29 | 2019-09-29 | Electromagnetic pulse hole flanging forming device for thick plate or thick arc-shaped part |
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| WO2023141807A1 (en) * | 2022-01-26 | 2023-08-03 | 重庆大学 | Hollow field shaper used for flat multi-turn coil |
| CN114871326B (en) * | 2022-04-02 | 2024-05-28 | 三峡大学 | Pipe bulging method and device adopting metal coating magnetic collector |
| CN114993857B (en) * | 2022-05-30 | 2024-05-10 | 武汉理工大学 | Metal plate electromagnetic forming limit experimental device with magnetic collector and experimental method |
| CN114799170B (en) * | 2022-05-31 | 2024-02-13 | 智磁(重庆)科技有限责任公司 | Spiral groove type flat plate magnetic collector applied to electromagnetic pulse axial pressing |
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