Electromagnetic forming device and method with synergistic effect of repulsive force and suction force

Abstract

The invention provides an electromagnetic forming method with synergistic effect of repulsive force and suction force, which comprises the following steps of: placing a plate to be formed between a female die and a main coil, and embedding a secondary coil into the female die; the main coil is powered on, eddy current is generated on the to-be-formed plate through the electromagnetic induction principle, the to-be-formed plate is subjected to electromagnetic repulsive force applied by the main coil, and therefore the plate is driven to flow into the female die and start to be formed; when the plate material deforms into the female die but is not completely attached to the inner wall of the female die, the auxiliary coil embedded into the female die is powered on to generate current, the plate material and the auxiliary coil attract each other through electromagnetic attraction force, and then the plate material is completely attached to the female die. According to the invention, a novel method of synergistic effect of electromagnetic forming and current suction is adopted, so that the forming height of a formed part is increased, the forming stress of the formed part is more uniform, and the degree that a plate is attached to the inner wall of the female die is improved.

Description

Technical Field

[0001] The invention belongs to the field of material plastic forming, and in particular relates to an electromagnetic forming device and method with synergistic effects of repulsive force and attractive force. Background Art

[0002] As an advanced metal processing method, electromagnetic forming technology has attracted much attention due to its high precision, non-contact, rapid forming and high production efficiency. The core principle of this technology is to use the current generated by the discharge of a pulse power supply to excite electromagnetic induction through a coil, so that a reverse induced current (eddy current) is generated on the metal sheet to be formed. In this process, the interaction between the excitation current and the induced current generates a strong electromagnetic repulsion, thereby driving the metal sheet to undergo plastic deformation.

[0003] However, in the plastic forming process of metal sheets, especially in the flanging process, traditional methods often face problems such as insufficient forming height and poor mold adhesion. These problems not only affect the quality and stability of the workpiece, but also limit the application of electromagnetic forming technology in a wider range of fields. Although electromagnetic forming flanging technology has improved compared to traditional flanging processes, it is still difficult to fully meet the forming requirements when processing complex shapes or large-sized workpieces. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes an electromagnetic forming method and device which can optimize the forming effect and make the repulsive force and attractive force of the sheet metal fit the mold to work together.

[0005] The technical solution of the present invention is as follows:

[0006] An electromagnetic forming method with synergistic repulsive and attractive forces comprises the following steps: placing a sheet material to be formed between a concave die and a main coil, and embedding a secondary coil into the concave die; The main coil is energized, and eddy currents are generated on the sheet to be formed using the principle of electromagnetic induction, so that the sheet to be formed is subjected to the electromagnetic repulsive force exerted by the main coil, thereby driving the sheet to flow into the die and begin to form; When the sheet metal is deformed into the die but has not yet completely fitted the inner wall of the die, the secondary coil embedded in the die is energized to generate current, and the sheet metal and the secondary coil are attracted to each other by electromagnetic attraction, thereby making the sheet metal completely fit the die. Furthermore, the eddy current generated on the sheet to be formed has the same direction as the current generated by the secondary coil. Furthermore, the current flowing through the primary coil is opposite to the current flowing through the secondary coil. The present invention also provides an electromagnetic forming device with synergistic repulsive and attractive forces, the device comprising: a sheet, a die, a blank holder, a main coil, a secondary coil and two power supply systems; wherein the sheet is placed between the die and the main coil, and is clamped by the blank holder and the die; the secondary coil is embedded in the die to generate electromagnetic attraction during the forming process; the power supply system is electrically connected to the main coil and the secondary coil, and is used to control the main coil and the secondary coil to generate electromagnetic force. Furthermore, the main coil is a single-turn or multi-turn coil. Furthermore, the secondary coil is a single turn or multiple turns, and each secondary coil is placed vertically. Furthermore, a magnetic concentrator is provided between the main coil and the sheet material to concentrate electromagnetic force and improve forming accuracy and efficiency. Furthermore, each power supply system includes a power supply, an energy storage capacitor, a voltage-dividing resistor and a control switch, which are used to provide a stable power supply and control the generation of electromagnetic force. Furthermore, the main coil and the auxiliary coil group are both connected to a power supply system, and the timing control of the discharge of the two power supply systems is achieved through the electronic control system.

[0007] Compared with the prior art, the present invention has the following advantages:

[0008] The present invention combines electromagnetic pulse induction forming with the principle that charged conductors attract in the same direction and repel in opposite directions to implement electromagnetic force driven forming. In the process of completing electromagnetic forming, it can not only improve the wrinkling, cracking and other phenomena caused by uneven stress distribution in the sheet metal forming process, but also improve the forming limit (drawing depth, flanging height) and at the same time make the formed sheet metal completely fit the die, thereby improving the forming accuracy.

[0009] The present invention improves the forming limit of metal materials, can effectively reduce the drawing or flanging coefficient, and reduce instability, cracking and the like; and the present invention adopts a high-rate forming method, which can reduce the springback and wrinkling of the formed part after forming. After the workpiece is subjected to the instantaneous electromagnetic force, it relies on inertia to complete the deformation, and the inertial force can slow down the occurrence of necking. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the description and claims, serve to illustrate the embodiments of the invention. Where appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

[0011] Figure 1 is the stress state of the maximum deformation area in the traditional flanging process;

[0012] Figure 2 This is a schematic diagram of a common electromagnetic flanging defect;

[0013] Figure 3 The schematic diagram of the synergistic effect of the repulsive force and the suction force of the sheet metal is shown in Example 1;

[0014] Figure 4 Schematic diagram of an electromagnetic forming device with coordinated repulsive and attractive forces as an example;

[0015] Figure 5 This is a schematic diagram of the initial state of the workpiece in Example 1;

[0016] Figure 6 This is a schematic diagram of the sheet material in Example 1 after the main coil discharges and flanging separately;

[0017] Figure 7 This is a schematic diagram of the sheet material in Example 1 after the main and auxiliary coils discharge in coordination and flanging;

[0018] Figure 8 The finite element model diagram of electromagnetic forming with suction synergy in Example 1;

[0019] Fig. 9 It is a cloud diagram of the induced eddy current vectors on the sheet in the electromagnetic forming finite element model with suction synergy in Example 1;

[0020] Fig.10 It is a vector cloud diagram of discharge current on the secondary coil in the electromagnetic forming finite element model with suction synergy in Example 1;

[0021] Fig.11 It is a vector cloud diagram of electromagnetic force (suction force) on the sheet in the electromagnetic forming finite element model with suction synergy in Example 1;

[0022] Fig.12 It is the stress cloud diagram of the sheet after deformation in the electromagnetic forming finite element model with repulsive force acting alone in Example 1;

[0023] Fig.13 It is the stress cloud diagram of the sheet after deformation in the electromagnetic forming finite element model with the synergistic effect of repulsive force and attractive force in Example 1;

[0024] Fig.14 This is a schematic diagram of the initial state of the workpiece in Example 2;

[0025] Fig.15 This is a schematic diagram of the sheet material in Example 2 after the main coil is discharged and flanging separately;

[0026] Fig.16 This is a schematic diagram of the sheet material in Example 2 after the main and auxiliary coils discharge in coordination and flanging;

[0027] Description of the numbers of the components in the figure:

[0028] 1: die, 2: sheet, 2-1: initial state of sheet, 2-2: sheet forming process, 2-3 end of sheet forming, 3-1: blank holder, 3-2: blank holder gasket, 4: main coil, 5: secondary coil, 6: discharge system, 7: magnetic collector. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] Example 1:

[0031] like Figure 3 FIG. 2 is a schematic diagram showing the principle of the synergistic effect of the repulsive force and the attractive force of the present invention; Figure 4 The new electromagnetic forming device with the synergistic effect of repulsive and attractive forces described in the present invention is shown, comprising a die 1, two coils and a discharge system; the sheet material 2 to be formed is placed between the die 1 and the main coil 4, and the secondary coil 5 is placed in the die 1. The secondary coil is a single-turn coil; the main coil is a multi-turn coil. The discharge system includes a plurality of power subsystems, each of which includes a power supply, an energy storage capacitor, a voltage-dividing resistor and a switch connected in series in sequence. The main coil 4 is electrically connected to the discharge system 6, and the secondary coil 3 is electrically connected to another discharge system 6.

[0032] The method for flanging by using the above-mentioned device with coordinated repulsive force and suction force specifically includes:

[0033] like Figure 5 As shown, first, the sheet material 2 to be formed is placed between the main coil 4 and the die 1. At this time, the sheet material 2 to be formed is located at the initial sheet material position 2-1, and the energy storage capacitor of the discharge system is charged. When the charging voltage reaches the forming voltage, the charging circuit is disconnected; at the same time, the switch of the discharge system 6 connected in series with the main coil 4 is closed, and the energy storage capacitor discharges the main coil 4 through the cable. The main coil 4 induces an electromagnetic force on the sheet material 2, so that the part of the sheet material to be formed located at the lower part of the die cavity of the die 1 is pushed to the second sheet material position 2-2, as shown in FIG. Figure 6 As shown; according to the discharge sequence, the switch of the discharge system 6 connected to the secondary coil 5 is closed, and the energy storage capacitor discharges to the secondary coil through the cable. The secondary coil 5 generates a current in the same direction as the eddy current of the sheet 2, and generates an electromagnetic attraction to the sheet 2, and cooperates with the main coil 4 to push the sheet 2 to the third sheet position 2-3 through the electromagnetic repulsion (direction away from the main coil 4) and the electromagnetic attraction (direction toward the secondary coil 5) on the sheet, so that the sheet 2 is completely fitted into the die 1, and finally the flanging of the sheet is completed, as shown Figure 7 In order to more clearly illustrate the process of the synergistic effect of electromagnetic repulsion and attraction, a finite element numerical model of the electromagnetic field is established, as shown in Figure 8As shown. The direction of the induced current received by the sheet 2 in the electromagnetic field is clockwise (the z-axis normal is outward). Fig. 9 As shown, the current of the secondary coil 5 is consistent with the eddy current on the sheet 2, as shown Fig.10 As shown, electromagnetic attraction is generated. The distribution of electromagnetic force generated by the synergistic effect of the main coil 4 and the secondary coil 5 on the sheet 2 in the electromagnetic field is shown in Fig.11 As shown. The electromagnetic force acting synergistically on sheet 2 ( Fig.11 The plastic deformation produced after Fig.13 As shown. Compared with the case where only the main coil 4 discharges alone (such as Fig.12 As shown in the figure, it can be seen that sheet 2 has better mold adhesion, higher flange height, more uniform stress distribution, and smaller maximum stress under the synergistic effect of repulsive force and suction force, thereby improving the forming conditions of the material.

[0034] Example 2:

[0035] By using the new electromagnetic forming device with the coordinated action of repulsive force and attractive force described in Example 1, a magnetic collector 7 can be placed between the sheet material 2 to be formed and the main coil 4, and the method for flanging forming specifically includes:

[0036] like Fig.14 As shown, first, the sheet material 2 to be formed is placed between the magnetic collector 7 and the die 1. At this time, the sheet material 2 to be formed is located at the initial sheet material position 2-1, and the energy storage capacitor of the discharge system 6 is charged. When the charging voltage reaches the forming voltage, the charging circuit is disconnected; at the same time, the switch of the discharge system 6 connected in series with the main coil 4 is closed, and the energy storage capacitor discharges the main coil through the cable. The main coil 4 simultaneously induces electromagnetic force on the sheet material 1 through the magnetic collector 7, so that the part of the sheet material 2 to be formed located at the lower part of the die cavity of the die 1 is pushed to the second sheet material position 2-2, as shown in FIG. Fig.15 As shown; according to the discharge sequence, the switch of the discharge system 6 connected to the secondary coil 5 is closed, and the energy storage capacitor discharges to the secondary coil through the cable. The secondary coil 5 generates a current in the same direction as the eddy current of the sheet 2, and generates an electromagnetic attraction to the sheet 2, and cooperates with the main coil 4 to push the sheet 2 to the third sheet position 2-3 through the electromagnetic repulsion (direction away from the main coil 4) and the electromagnetic attraction (direction toward the secondary coil 5) on the sheet, so that the sheet 2 is completely fitted into the die 1, and finally the flanging of the sheet is completed, as shown Fig.16 .

[0037] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An electromagnetic forming method with synergistic effects of repulsive force and attractive force, characterized in that: The steps include: The sheet to be formed is placed between the die and the main coil, and the secondary coil is embedded in the die; The main coil is energized, and eddy currents are generated on the sheet to be formed using the principle of electromagnetic induction, so that the sheet to be formed is subjected to the electromagnetic repulsive force exerted by the main coil, thereby driving the sheet to flow into the die and begin to form; When the sheet metal is deformed into the die but has not yet completely fitted the inner wall of the die, the secondary coil embedded in the die is energized to generate current, and the sheet metal and the secondary coil are attracted to each other by electromagnetic attraction, thereby making the sheet metal completely fit the die.

2. The electromagnetic forming method with synergistic effects of repulsive force and attractive force according to claim 1, characterized in that: The eddy current generated on the sheet to be formed has the same direction as the current generated by the secondary coil.

3. The electromagnetic forming method with synergistic effects of repulsive force and attractive force according to claim 1, characterized in that: The current flowing through the main coil is opposite to the current flowing through the auxiliary coil.

4. An electromagnetic forming device with synergistic repulsive and attractive forces, characterized in that: The device comprises: Sheet material, die, blank holder, main coil, auxiliary coil and two power supply systems; wherein the sheet material is placed between the die and the main coil, and is clamped by the blank holder and the die; the auxiliary coil is embedded in the die to generate electromagnetic attraction during the forming process; the power supply system is electrically connected to the main coil and the auxiliary coil, and is used to control the main coil and the auxiliary coil to generate electromagnetic force.

5. The electromagnetic forming device with coordinated repulsive and attractive forces according to claim 4, characterized in that: The main coil is a single-turn or multi-turn coil.

6. The electromagnetic forming device with coordinated repulsive and attractive forces according to claim 4, characterized in that: The secondary coil is a single-turn or multi-turn secondary coil, and each secondary coil is placed vertically.

7. The electromagnetic forming device with coordinated repulsive and attractive forces according to claim 4, characterized in that: A magnetic collector is also included between the main coil and the sheet material to concentrate the electromagnetic force and improve the forming accuracy and efficiency.

8. The electromagnetic forming device with coordinated repulsive and attractive forces according to claim 4, characterized in that: Each power supply system includes a power supply, an energy storage capacitor, a voltage dividing resistor and a control switch, and is used to provide a stable power supply and control the generation of electromagnetic force.

9. The electromagnetic forming device with coordinated repulsive and attractive forces according to claim 4, characterized in that: The main coil and the auxiliary coil group are both connected to a power supply system, and the timing control of the discharge of the two power supply systems is achieved through the electronic control system.

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