Electromagnetically driven sheet material surface impact toughening chemical device and process thereof

Abstract

The present invention discloses an electromagnetically driven sheet metal surface impact toughening chemical device and its process. The electromagnetically driven sheet metal surface impact toughening chemical device comprises a workbench, a pressure edge positioning device, and a step-by-step rotation drive output end. An outer cylinder sleeve is fixedly arranged above the top surface of the workbench, and an electromagnetic drive coil is embedded in the top of the outer cylinder sleeve. The bottom end of the step-by-step rotation drive output end is fixedly connected with an electromagnet assembly, and a high-alloy steel punch is movably arranged inside the outer cylinder sleeve. A copper ring is fixedly arranged on the top of the high-alloy steel punch, and uniformly distributed steel balls are arranged on the bottom surface of the high-alloy steel punch. The present invention replaces traditional projectiles by introducing a punch with raised high-strength steel balls to achieve short-cycle, high-frequency, repeated high-speed impact and efficient shot peening treatment of the punch on the sheet metal surface. By adopting a full-coverage multiple impact strengthening mode, the fatigue strength of the sheet metal is improved, the process flow is simplified, the manufacturing cycle is shortened, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal plastic processing and forming, in particular to an electromagnetically driven sheet material surface impact toughening chemical device and a process thereof. Background Art

[0002] Ribbed panels, represented by spacecraft panels, cabin sections, rudder wings, tank short shells, aircraft fuselages and wing panels, are key load-bearing components in aerospace launch equipment. They use lightweight and high-strength materials and multi-ribbed overall weight-reducing structures, and are an important development direction for high-performance lightweight components in the aerospace field. However, extreme service environments such as alternating loads have high requirements on the fatigue strength of panels. The fatigue resistance of metal materials is closely related to their surface roughness, surface residual stress, microstructure, hardness and damage condition. At present, surface strengthening technology is widely used at home and abroad to improve the fatigue strength of materials.

[0003] Shot peening is a cold working surface strengthening process commonly used at present. Shot peening can effectively improve the fatigue resistance of metal parts by introducing surface residual compressive stress and a certain degree of surface hardening. The selection of shot peening process parameters, such as shot peening intensity, shot material, shot impact surface coverage, etc., has a significant impact on the surface morphology of the workpiece and the distribution of its residual stress field, and thus has a significant impact on the fatigue life of the parts. Shot peening intensity and coverage are the main process parameters that affect the surface integrity and fatigue resistance of the material during shot peening. However, for different metal materials, their influence rules are different, and there is a more complex interaction between the two. Shots with low breakage rate can effectively improve work efficiency and surface forming quality. However, the shot flow generated by shot peening continuously impacts the workpiece and forms dense pits on its surface, resulting in increased surface roughness. Many inappropriate process parameters may even cause cracking and partial detachment of the workpiece surface, which damages the surface integrity of the metal material and is not conducive to the improvement of fatigue performance. Summary of the invention

[0004] In view of the above-mentioned defects and shortcomings, the present invention provides an electromagnetically driven sheet metal surface impact toughening chemical device and process thereof. By introducing a punch with raised high-strength steel balls to replace traditional projectiles, timing design and control are carried out based on electromagnetic forming and electromagnet systems. Through electromagnetic force adsorption and strong Lorentz force interaction, short-cycle, high-frequency repeated high-speed impact and efficient shot peening strengthening treatment of the sheet metal surface by the punch are achieved. Multi-pass continuous impact strengthening is achieved by driving the punch to rotate in a step-by-step manner, and full-coverage multiple impact strengthening is achieved to improve the fatigue strength of the sheet metal.

[0005] In order to solve the above technical problems, a technical solution adopted by the present invention is:

[0006] An electromagnetically driven sheet material surface impact toughening chemical device comprises a workbench, a pressure edge positioning device arranged on both sides of the top surface of the workbench, and a step-by-step rotation driving output end arranged above the top surface of the workbench. Both sides of the sheet material whose surface is to be impact-strengthened are fixedly clamped on the top surface of the workbench through the pressure edge positioning device. A suspended outer cylinder sleeve is fixedly arranged above the top surface of the workbench, and an electromagnetic driving coil is embedded in the top of the outer cylinder sleeve. The bottom end of the step-by-step rotation driving output end is fixedly connected to an electromagnet assembly located above the electromagnetic driving coil. A high-alloy steel punch located below the electromagnetic driving coil and adsorbed by the electromagnetic assembly through a magnetic field force is movably arranged inside the outer cylinder sleeve. When the step-by-step rotation driving output end drives the electromagnetic assembly to step and rotate, the high-alloy steel punch rotates synchronously. A copper ring that can be pushed by the electromagnetic driving coil through the Lorentz force is fixedly arranged on the top of the high-alloy steel punch. The bottom surface of the high-alloy steel punch is provided with uniformly distributed steel balls, and the bottom ends of the steel balls protrude from the bottom surface of the high-alloy steel punch.

[0007] It also includes an electromagnet control circuit for controlling the on-off power supply of the electromagnet assembly, and an electromagnetic forming system circuit for controlling the on-off power supply of the electromagnetic drive coil.

[0008] Furthermore, the electromagnet assembly includes an electromagnet core fixedly connected to the stepping rotation drive output end, an electromagnet coil is fixedly sleeved on the outer side of the electromagnet core, and an electromagnet shell is fixedly sleeved on the outer side of the bottom of the electromagnet coil.

[0009] Furthermore, the number of the electromagnet coils is multiple and evenly distributed in the electromagnet housing, and the top of the outer wall of the high-alloy steel punch is provided with magnetic suction blocks with the same number as the electromagnet coils.

[0010] Furthermore, a guide telescopic rod is fixedly connected to the center of the bottom surface of the electromagnet housing, and the bottom end of the guide telescopic rod passes through the electromagnetic drive coil and is fixedly connected to the center of the top surface of the high-alloy steel punch.

[0011] Furthermore, the outer wall of the high alloy steel punch is in sliding contact with the inner wall of the outer cylinder sleeve.

[0012] Furthermore, a limiting boss located above the top of the outer wall of the high alloy steel punch is fixedly provided on the inner wall of the outer tube sleeve. When the high alloy steel punch is in the highest position, a gap is left between the top surface of the copper ring and the bottom surface of the electromagnetic drive coil.

[0013] Furthermore, the bottom end of the surface of the steel ball protrudes from the bottom surface of the high alloy steel punch by 1-3 mm.

[0014] A process for electromagnetically driven sheet metal surface impact toughening is also provided, which is applied to the electromagnetically driven sheet metal surface impact toughening process as described above and includes the following steps:

[0015] S1. Mould positioning: Turn on the electromagnet control circuit, and the electromagnet assembly is energized to generate an electromagnetic field, which pre-adsorbs the high alloy steel punch on the upper part of the outer tube sleeve;

[0016] S2. Sheet material positioning: fix the sheet material to be processed on the workbench through the edge pressing positioning device;

[0017] S3, first strengthening: the electromagnetic forming system circuit is turned on, the electromagnetic drive coil is energized to release the Lorentz force on the copper ring, and the high-alloy steel punch with a steel ball on the bottom is driven to impact the sheet surface at high speed, leaving uniform tiny pits on the surface of the sheet, thereby actively constructing a residual stress field and surface work hardening on the surface of the sheet;

[0018] S4, repeated strengthening: through the preset timing control loop, the electromagnet control circuit provides direct current to the electromagnet assembly and the electromagnetic forming system circuit provides high-voltage pulse current to the electromagnetic drive coil alternately, so that the electromagnet assembly absorbs the high-alloy steel punch to rise and the electromagnetic drive coil drives the high-alloy steel punch to impact downward alternately;

[0019] S5, full coverage strengthening: In step S4, each time the electromagnet assembly absorbs the high alloy steel punch and rises, the stepping rotation drive output end drives the electromagnet assembly to rotate a preset step angle, and the high alloy steel punch rotates synchronously at the same angle, so that the steel balls at the bottom of the high alloy steel punch step by step to perform full coverage multiple impact strengthening on the surface of the sheet material;

[0020] S6, taking out the sample: after the strengthening process is carried out for a preset time, the power supply of the electromagnetic forming system circuit is disconnected, the edge holding positioning device is turned on, the sheet is taken out, and the electromagnet control circuit is turned off;

[0021] S7. Performance testing: Test the strengthening effect and surface quality performance of the removed sheet. If the test results do not meet the preset requirements, repeat the above steps to impact strengthen the surface of the sheet again.

[0022] Furthermore, the diameter of the electromagnet core is 100-500mm, the wire diameter of the electromagnet coil is 2mm, the number of turns is 600-1500, the rated voltage is 20-50V, the working current is 0.5A-5A, and the maximum suction force of the electromagnet assembly on the upper end of the outer wall of the high-alloy steel punch is not less than 200N, and the minimum suction force is not less than the sum of the gravity of the high-alloy steel punch and the copper ring.

[0023] Furthermore, the electromagnetic drive coil has 4 layers in the coil height direction, 10 turns in a single layer, and is wound by a rectangular copper wire with a cross-sectional area of ​​2mm*4mm. The actual discharge voltage is 7-15kV, and the discharge interval charging time is 10-20s.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention utilizes an electromagnetic forming system to drive a high-alloy steel punch with a high-strength steel ball to impact the sheet metal surface at high speed through the Lorentz force released by an electromagnetic drive coil, thereby introducing a residual stress field and a certain degree of surface work hardening to improve the fatigue strength of the sheet metal. The high strain rate driving feature of electromagnetic forming (strain rate 10 3 -10 4 s -1 , impact speed 100-200 m / s), can actively use the "high-speed superplasticity" effect in high-speed deformation to effectively improve the material forming limit, avoid surface cracking, improve surface integrity, and use the high strain rate hardening effect of high-speed deformation to improve the surface strengthening effect;

[0026] 2. The present invention uses a high-alloy steel punch with a steel ball at the bottom to impact the sheet metal surface at high speed under the action of the Lorentz force. Different from the traditional shot peening process of impacting the sheet metal surface, the strengthening uniformity is significantly improved, the introduced residual stress field is also more uniform, the probability of cracking and falling off of the sheet metal during the strengthening process is reduced, and the surface quality is improved;

[0027] 3. The present invention introduces circuit timing control by designing an electromagnet control system + an electromagnetic forming control system to realize the alternating action of electromagnet adsorption + electromagnetic drive impact, which can achieve high-speed impact with short cycle and high frequency, simplifies the process flow, and greatly improves product quality and production efficiency;

[0028] 4. The rotatable electromagnet assembly designed in the present invention can drive the high-alloy steel punch to rotate synchronously, so as to realize multiple impacts of the steel balls on the surface of the sheet metal in a comprehensive coverage manner. The copper ring embedded in the high-alloy steel punch solves the problem of low magnetic permeability of the alloy steel. The designed high-strength and high-magnetic permeability punch can effectively achieve high-speed and high-quality strengthening effects. At the same time, the uniform distribution of steel balls can realize the introduction of a uniform residual stress field, avoiding the occurrence of surface cracking and falling off problems caused by unevenness, and improving the strengthening quality of the sheet metal surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the structure of the electromagnetically driven sheet material surface impact toughening chemical device in Example 1;

[0030] Figure 2 Schematic diagram of the positional relationship between the electromagnetic drive coil and the copper ring in the present invention;

[0031] Figure 3 Schematic diagram of the distribution of steel balls at the bottom of the high alloy steel punch in the present invention;

[0032] Figure 4It is a waveform diagram of the current timing control in the electromagnetically driven sheet material surface impact toughening process of the present invention;

[0033] Figure 5 This is a schematic diagram of the structure of the electromagnetically driven sheet material surface impact toughening chemical device in Example 2;

[0034] Figure 6 The figure is a schematic diagram of the strain simulation test on the impact strengthening of sheet metal using the tooling and process of the present invention, wherein part (a) is the strain simulation test result after one impact strengthening is completed on the sheet metal surface, and part (b) is the strain simulation test result after two impact strengthening is completed on the sheet metal surface.

[0035] In the figure: 1. Electromagnet coil; 2. Electromagnet core; 3. Electromagnet control circuit; 4. Electromagnet housing; 5. Electromagnet drive coil; 6. Copper ring; 7. High alloy steel punch; 8. Outer tube sleeve; 9. Electromagnetic forming system circuit; 10. Edge pressing positioning device; 11. Sheet material. DETAILED DESCRIPTION

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The present invention provides an electromagnetically driven sheet metal surface impact toughening chemical device, comprising a workbench, a pressure edge positioning device 10 arranged on both sides of the top surface of the workbench, and a stepping rotation drive output end (not shown in the figure) arranged above the top surface of the workbench. Both sides of the sheet metal 11 to be impact-strengthened are fixedly clamped on the top surface of the workbench through the pressure edge positioning device 10. The workbench and the pressure edge positioning device 10 adopt existing metal sheet metal electric-assisted forming equipment, and the stepping rotation drive output end adopts an existing servo motor-driven gantry structure, which can be directly fixed on the top surface of the workbench. All of them are existing technologies and will not be described in detail here.

[0040] Embodiment 1:

[0041] A suspended outer tube sleeve 8 is fixedly provided above the top surface of the workbench. The outer tube sleeve 8 is a hollow cylindrical structure, and its outer wall is fixed to the top surface of the workbench by a bracket (shown in the figure), so that it is suspended above the impact part of the sheet 11. After the sheet 11 is fixed to the top surface of the workbench by the edge clamping positioning device 10, the bottom end of the outer tube sleeve 8 is located near the top surface of the sheet 11, which plays an axial guiding and radial limiting role for the lifting and lowering movement of the high alloy steel punch 7 located in the outer tube sleeve 8. Preferably, the bracket adopts a height-adjustable structure (such as a base and a top beam structure connected by screws) to be able to adjust the vertical distance between the bottom end of the outer tube sleeve 8 and the top surface of the workbench, thereby meeting the impact strengthening requirements of sheets 11 of different thicknesses.

[0042] The top of the outer tube sleeve 8 is embedded with an electromagnetic drive coil 5, and the tooling is equipped with an electromagnetic forming system circuit 9 for controlling the power supply on and off of the electromagnetic drive coil 5; the bottom end of the stepping rotation drive output end is fixedly connected to an electromagnet assembly located above the electromagnetic drive coil 5, and the tooling is equipped with an electromagnet control circuit 3 for controlling the power supply on and off of the electromagnet assembly. The electromagnetic forming system circuit 9 adopts the existing high-voltage pulse output circuit structure, and the electromagnet control circuit 3 adopts the existing DC power supply voltage regulation output circuit structure, which will not be described here.

[0043] The outer tube sheath 8 is provided with a high alloy steel punch 7 located below the electromagnetic drive coil 5 and can be attracted by the electromagnetic assembly through the magnetic field force, and a copper ring 6 is fixedly provided on the top of the high alloy steel punch 7. The electromagnetic assembly includes an electromagnetic core 2 fixedly connected to the stepping rotation drive output end, an electromagnetic coil 1 is fixedly sleeved on the outer side of the electromagnetic core 2, and an electromagnetic housing 4 is fixedly sleeved on the outer side of the bottom of the electromagnetic coil 1.

[0044] In this embodiment, the number of electromagnet coils 1 is 3, and they are evenly distributed in the electromagnet housing 4, that is, the central angle between the axis line of the outer tube sheath 8 and the same position of two adjacent electromagnet coils 1 is 120°, the diameter of the electromagnet core 2 is 100-500mm, the wire diameter of the electromagnet coil 1 is 2mm, and the number of turns is 600-1500. The high-alloy steel punch 7 is a cylindrical shell structure with an open top, made of high-alloy steel material with low magnetic permeability, and the top of the outer wall of the high-alloy steel punch 7 is provided with the same number of magnetic blocks as the electromagnet coils 1 (not shown in the figure). The electromagnetic drive coil 5 has 4 layers in the coil height direction, and the number of turns of a single layer is 10. It is wound by a rectangular copper wire with a cross-sectional area of ​​2mm*4mm.

[0045] When the electromagnet coil 1 is energized, an electromagnetic field is generated, thereby adsorbing the magnetic block below it, so that the high alloy steel punch 7 can rise vertically under the adsorption of the magnetic field force. Figure 2 As shown, a limiting boss located above the top of the outer wall of the high alloy steel punch 7 is fixedly arranged on the inner wall of the outer tube sleeve 8. When the high alloy steel punch 7 rises to the point where its top surface fits with the bottom surface of the limiting boss under the adsorption of the magnetic field force, the high alloy steel punch 7 is at the highest position, and at this time, a gap d is left between the top surface of the copper ring 6 and the bottom surface of the electromagnetic drive coil 5. Further preferably, a rubber pad (not shown in the figure) is fixedly arranged on the bottom surface of the limiting boss. When the high alloy steel punch 7 rises to the highest position, its top surface hits the rubber pad, which can avoid the rigid impact between the high alloy steel punch 7 and the limiting boss, and play a role of buffer protection.

[0046] The copper ring 6 and the high alloy steel punch 7 are tightened by heat fitting. When the electromagnetic drive coil 5 is energized, the copper ring 6 can move downward at high speed due to the strong Lorentz force excited by the electromagnetic drive coil 5 because the copper material has good magnetic conductivity. The spacing d between the bottom surface of the electromagnetic drive coil 5 and the top surface of the copper ring 6 is 2 mm to ensure that the electromagnetic drive coil 5 can provide sufficient Lorentz force to the copper ring 6 after being energized. The copper ring 6 is a hollow ring structure. One of its functions is to reduce the weight of the copper ring 6 itself to increase the impact speed under the same Lorentz force, thereby improving processing efficiency and reducing production costs. The second function is that since the central part of the electromagnetic drive coil 5 is a hollow structure, no Lorentz force is generated in the hollow part corresponding to the copper ring 6.

[0047] The bottom surface of the high alloy steel punch 7 is provided with uniformly distributed steel balls, which are made of high strength alloy material, and the bottom end of the surface of the steel balls protrudes from the bottom surface of the high alloy steel punch 7, such as Figure 3As shown, in this embodiment, the bottom end of the surface of the steel ball protrudes from the bottom surface of the high alloy steel punch 7 by 1-3 mm. When the copper ring 6 moves downward at high speed under the action of the Lorentz force, it synchronously drives the high alloy steel punch 7 to impact the surface of the sheet 11 at high speed, and the steel ball leaves uniform tiny pits on the surface of the sheet 11, thereby actively constructing a residual stress field and surface work hardening on the surface of the sheet 11.

[0048] The outer wall of the high alloy steel punch 7 is in sliding contact with the inner wall of the outer tube sleeve 8 to ensure that the central axis of the high alloy steel punch 7 can always remain vertical during the lifting process. Preferably, a rolling steel ball is embedded in the top side of the high alloy steel punch 7, one of the functions is to make the high alloy steel punch 7 and the outer tube sleeve 8 coaxially arranged, and the second function is to ensure that the high alloy steel punch 7 can simultaneously complete axial movement and circumferential rotation in the outer tube sleeve 8, and reduce contact friction during relative movement. The bottom steel ball and the side steel ball are respectively embedded in the corresponding circular holes, and the top of the bottom steel ball is pressed and fixed by a pressure plate (not shown in the figure) parallel to the bottom wall of the high alloy steel punch 7 and connected by screws, and the side steel ball is clamped and positioned by multiple inner arc pressure plates (not shown in the figure) coaxially arranged with the annular side wall of the high alloy steel punch 7 and connected by screws. The detachable screw connection method is adopted to facilitate the local replacement of the steel ball when it is damaged.

[0049] Obviously, the high alloy steel punch 7 and the steel ball at its bottom can also be set as an integrated structure, that is, the bottom surface of the high alloy steel punch 7 is formed into an array of spherical protrusions through CNC milling. This structure can also achieve the function of the impact punch of the present invention, but the manufacturing, use and maintenance costs are relatively high.

[0050] When the step-by-step rotation drive output end drives the electromagnet assembly to step and rotate, the high-alloy steel punch 7 rotates synchronously. Specifically, the electromagnet assembly realizes the vertical rise of the high-alloy steel punch 7 by adsorbing the magnetic suction blocks arranged at intervals at the top of the side wall of the high-alloy steel punch 7. When the electromagnetic drive coil 5 is powered off, the Lorentz force generated by it on the copper ring 6 is reduced until it disappears, the electromagnet assembly is powered on and adsorbs the high-alloy steel punch 7, and the high-alloy steel punch 7 rises vertically. In this process, the electromagnet assembly steps and rotates a preset angle. Under the action of the magnetic field adsorption force, the magnetic suction block at the top of the side wall of the high-alloy steel punch 7 will automatically move toward the new position of the electromagnet assembly, thereby forming a rotation torque on the high-alloy steel punch 7, so that the high-alloy steel punch 7 rotates the same angle as the electromagnet assembly. In this way, in the cycle mode of magnetic adsorption, rising and stepping rotation and Lorentz force driving high-speed downward impact, the steel balls at the bottom of the high-alloy steel punch 7 can achieve full coverage and multiple impact strengthening on the surface of the sheet 11.

[0051] In this embodiment, the electromagnet control circuit 3 provides a direct current to the electromagnet assembly, and the electromagnetic forming system circuit 9 provides a high-voltage pulse current to the electromagnetic drive coil 5. The two currents are provided alternately according to preset timing control conditions, such as Figure 4 As shown, a series of repeated strengthening treatment processes of "impact-pull back-impact-pull back..." of the high alloy steel punch 7 can be realized.

[0052] Embodiment 2:

[0053] Compared with the embodiment 1, the main difference of this embodiment is that: the bottom center of the electromagnet housing 4 is fixedly connected with a guide telescopic rod, and the bottom end of the guide telescopic rod penetrates the electromagnetic drive coil 5 and is fixedly connected with the top center of the high alloy steel punch 7. In this way, when the electromagnet assembly is energized to generate a magnetic field, the high alloy steel punch 7 can be attracted by the electromagnetic force and rise, and when the electromagnetic drive coil 5 is energized to generate a Lorentz force on the copper ring 6, the high alloy steel punch 7 can be pushed and moved down at high speed. Under the guiding action of the guide telescopic rod, the high alloy steel punch 7 can be lifted and lowered vertically, and its outer side wall does not need to contact the inner wall of the outer tube sleeve 8; the rod of the guide telescopic rod can only move relative to the axial direction, and cannot rotate relative to the axial direction. In this way, when the electromagnet assembly is stepped and rotated by a preset angle, the high alloy steel punch 7 rotates synchronously under the connection action of the guide telescopic rod. Therefore, the electromagnet coil 1 only needs to be a complete annular structure. Since the centers of the electromagnetic drive coil 5 and the copper ring 6 are both hollow structures, the guide telescopic rod is exactly at the center of the hollow position.

[0054] The present invention also provides an electromagnetically driven sheet metal surface impact toughening process, which is applied to the electromagnetically driven sheet metal surface impact toughening chemical equipment as described above, and comprises the following steps:

[0055] S1. Mould positioning: Turn on the electromagnet control circuit 3, and the electromagnet assembly is energized to generate an electromagnetic field, and the high-alloy steel punch 7 is pre-adsorbed above the inner part of the outer tube sleeve. Among them, the rated voltage applied to the electromagnet coil 1 is 20-50V, the working current is 0.5A-5A, and the maximum suction force of the electromagnet assembly on the upper end of the outer wall of the high-alloy steel punch 7 is not less than 200N, and the minimum suction force is not less than the sum of the gravity of the high-alloy steel punch 7 and the copper ring 6, so as to ensure that the electromagnetic field force generated after power is sufficient to lift the high-alloy steel punch 7 and the copper ring 6 upward.

[0056] S2, sheet positioning: fix the sheet 11 to be processed on the workbench through the edge pressing positioning device 10;

[0057] S3, first strengthening: turn on the electromagnetic forming system circuit, energize the electromagnetic drive coil 5 to release the Lorentz force on the copper ring 6, drive the high alloy steel punch 7 with a steel ball on the bottom to impact the surface of the sheet 11 at high speed, leave uniform tiny pits on the surface of the sheet 11, and actively build a residual stress field and surface work hardening on the surface of the sheet 11. Among them, the maximum discharge energy of the electromagnetic forming system circuit 9 is 120-200 kJ, the capacitor capacitance is continuously adjustable from 0 to 320 μF, and two capacitances of 160 μF and 320 μF are used. The actual discharge voltage is 7-15 kV, and the discharge interval charging time is 10-20s.

[0058] S4, repeated strengthening: through the preset timing control loop, the electromagnet control circuit 3 provides direct current to the electromagnet assembly and the electromagnetic forming system circuit 9 provides high-voltage pulse current to the electromagnetic drive coil 5 alternately, so that the electromagnet assembly absorbs the high-alloy steel punch 7 to rise and the electromagnetic drive coil 5 drives the high-alloy steel punch 7 to impact downward alternately. In this embodiment, it is preset to achieve a maximum of 6 impacts within 1 minute, so the minimum single cycle of the alternation of the two currents is 10s.

[0059] S5, full coverage strengthening: In step S4, each time the electromagnet assembly absorbs the high alloy steel punch 7 and rises, the stepping rotation drive output end drives the electromagnet assembly to rotate a preset step angle, and the high alloy steel punch 7 rotates synchronously at the same angle, so that the steel balls at the bottom of the high alloy steel punch 7 step by step perform full coverage multiple impact strengthening on the surface of the sheet 11. In this embodiment, after each adsorption, the preset single step rotation angle of the stepping rotation drive output end is 60°, which in turn drives the electromagnet assembly and the high alloy steel punch 7 to rotate synchronously by 60°. During the 6 impact processes, the high alloy steel punch 7 is rotated 360°, and finally the steel balls at the bottom of the high alloy steel punch 7 are fully covered multiple impact strengthening on the surface of the sheet 11.

[0060] S6, taking out the sample: after the strengthening process is carried out for a preset time (set to 2 minutes in this embodiment), the power supply of the electromagnetic forming system circuit 9 is disconnected, the edge holding positioning device 10 is turned on, the sheet 11 is taken out, and the electromagnet control circuit 3 is turned off;

[0061] S7. Performance testing: The taken-out sheet material 11 is subjected to a performance test on the strengthening effect and the surface quality. Specifically, the strengthening effect and the surface quality are tested by a microhardness test and a surface observation using a laser confocal microscope. If the test result does not meet the preset requirements, the above steps are repeated to impact strengthen the surface of the sheet material 11 again.

[0062] like Figure 6As shown, the surface impact strengthening simulation test results of TC4 material sheet material made by WAAM (wire arc additive manufacturing) are performed using the electromagnetically driven sheet material surface impact toughening chemical equipment and process of the present invention. The left part (a) is the simulation test strain result after the sheet material surface is completed with one impact strengthening, and the right part (b) is the simulation test strain result after the sheet material surface is completed with two impact strengthening. It can be seen from the results that after the first surface impact strengthening shown in the left part (a), the high alloy steel punch accumulates plastic strain in the form of a lattice on the sheet material surface, and the strain reaches about 0.5. After the subsequent two impacts, the electromagnet synchronously drives the high alloy steel punch to rotate 60°, and a secondary residual strain is introduced on the basis of the first impact strengthening. It can be seen from the right part (b) that the strain accumulation is more uniform than the first time, and the strain is deepened, and the maximum value reaches about 1.0. It can be inferred from the two strengthening effects that after 6 impacts, the steel ball at the bottom of the high alloy steel punch 7 can finally achieve full coverage of the sheet material 11 surface multiple impact strengthening.

[0063] The same sheet material was used for actual impact strengthening test, and the strengthening effect and surface quality performance were tested. Specifically, the characteristic area after impact strengthening was selected for Vickers hardness (HV) performance test. The results showed that compared with the hardness value of 297.49HV of the initial material, the hardness value after impact strengthening increased to 378.52HV, with a significant improvement effect. The actual test results are consistent with the performance results expected by the simulation results.

[0064] 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.

[0065] 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 electromagnetically driven sheet material surface impact toughening chemical device, comprising a workbench, edge pressing positioning devices (10) arranged on both sides of the top surface of the workbench, and a stepping rotation drive output end arranged above the top surface of the workbench, wherein both sides of the sheet material (11) whose surface is to be impact-hardened are fixedly clamped on the top surface of the workbench by the edge pressing positioning devices (10), and characterized in that: A suspended outer cylinder sleeve (8) is fixedly arranged above the top surface of the workbench, an electromagnetic drive coil (5) is embedded in the top of the outer cylinder sleeve (8), the bottom end of the stepping rotation drive output end is fixedly connected to an electromagnet assembly located above the electromagnetic drive coil (5), a high-alloy steel punch (7) located below the electromagnetic drive coil (5) and capable of being adsorbed by the electromagnetic assembly through a magnetic field force is movably arranged inside the outer cylinder sleeve (8), when the stepping rotation drive output end drives the electromagnetic assembly to step and rotate, the high-alloy steel punch (7) rotates synchronously, a copper ring (6) that can be pushed by the electromagnetic drive coil (5) through a Lorentz force is fixedly arranged on the top of the high-alloy steel punch (7), and uniformly distributed steel balls are arranged on the bottom surface of the high-alloy steel punch (7), and the bottom ends of the steel balls protrude from the bottom surface of the high-alloy steel punch (7); It also includes an electromagnet control circuit (3) for controlling the power supply on and off of the electromagnet assembly, and an electromagnetic forming system circuit (9) for controlling the power supply on and off of the electromagnetic drive coil (5). Through a pre-set timing control loop, the electromagnet control circuit (3) provides a direct current to the electromagnet assembly and the electromagnetic forming system circuit (9) provides a high-voltage pulse current to the electromagnetic drive coil (5) alternately, so that the electromagnet assembly absorbs the high-alloy steel punch (7) to rise and the electromagnetic drive coil (5) drives the high-alloy steel punch (7) to impact downward alternately. When the stepping rotation drive output end drives the electromagnet assembly to stepwise rotate, the high-alloy steel punch (7) rotates synchronously, so that the steel balls at the bottom of the high-alloy steel punch (7) step by step to perform full-coverage multiple impact strengthening on the surface of the sheet material (11).

2. The electromagnetically driven sheet material surface impact toughening chemical device according to claim 1, characterized in that: The electromagnet assembly comprises an electromagnet core (2) fixedly connected to the stepping rotation drive output end, an electromagnet coil (1) is fixedly sleeved on the outer side of the electromagnet core (2), and an electromagnet housing (4) is fixedly sleeved on the outer side of the bottom of the electromagnet coil (1).

3. The electromagnetically driven sheet material surface impact toughening chemical device according to claim 2, characterized in that: The number of the electromagnet coils (1) is multiple and evenly distributed in the electromagnet housing (4); the top end of the outer wall of the high-alloy steel punch (7) is provided with magnetic suction blocks of the same number as the number of the electromagnet coils (1).

4. The electromagnetically driven sheet material surface impact toughening chemical device according to claim 2, characterized in that: A guide telescopic rod is fixedly connected to the center of the bottom surface of the electromagnet housing (4); the bottom end of the guide telescopic rod passes through the electromagnetic drive coil (5) and is fixedly connected to the center of the top surface of the high-alloy steel punch (7).

5. The electromagnetically driven sheet material surface impact toughening chemical device according to claim 3 or 4, characterized in that: The outer wall of the high alloy steel punch (7) is in sliding contact with the inner wall of the outer cylinder jacket (8).

6. The electromagnetically driven sheet material surface impact toughening chemical device according to claim 3 or 4, characterized in that: A limiting boss located above the top end of the outer wall of the high-alloy steel punch (7) is fixedly provided on the inner wall of the outer cylinder sleeve (8); when the high-alloy steel punch (7) is at the highest position, a gap is left between the top surface of the copper ring (6) and the bottom surface of the electromagnetic drive coil (5).

7. An electromagnetically driven sheet material surface impact toughening chemical device according to any one of claims 2 to 4, characterized in that: The bottom end of the surface of the steel ball protrudes from the bottom surface of the high alloy steel punch (7) by a distance of 1-3 mm.

8. An electromagnetically driven sheet metal surface impact toughening process, applied to the electromagnetically driven sheet metal surface impact toughening process as claimed in any one of claims 2 to 7, characterized in that: The following steps are involved: S1, mold positioning: the electromagnet control circuit (3) is turned on, and the electromagnet assembly is energized to generate an electromagnetic field, so that the high alloy steel punch (7) is pre-adsorbed on the upper part of the inner part of the outer tube sleeve; S2, sheet positioning: fixing the sheet to be processed (11) on the workbench through the edge pressing positioning device (10); S3, first strengthening: the electromagnetic forming system circuit is turned on, the electromagnetic drive coil (5) is energized to release the Lorentz force on the copper ring (6), and the high-alloy steel punch (7) with a steel ball on the bottom surface is driven to impact the surface of the sheet (11) at high speed, leaving uniform tiny pits on the surface of the sheet (11), thereby actively constructing a residual stress field and surface work hardening on the surface of the sheet (11); S4, repeated strengthening: through a preset timing control loop, the electromagnet control circuit (3) provides a direct current to the electromagnet assembly and the electromagnetic forming system circuit (9) provides a high-voltage pulse current to the electromagnetic drive coil (5) alternately, so that the electromagnet assembly absorbs the high-alloy steel punch (7) upward and the electromagnetic drive coil (5) drives the high-alloy steel punch (7) downward alternately; S5, full coverage strengthening: In step S4, each time the electromagnet assembly absorbs the high alloy steel punch (7) to rise, the stepping rotation drive output end drives the electromagnet assembly to rotate by a preset stepping angle, and the high alloy steel punch (7) rotates synchronously by the same angle, so that the steel balls at the bottom of the high alloy steel punch (7) step by step perform full coverage multiple impact strengthening on the surface of the sheet material (11); S6, taking out the sample: after the strengthening process has been carried out for a preset time, the power supply of the electromagnetic forming system circuit (9) is disconnected, the edge holding positioning device (10) is turned on, the sheet material (11) is taken out, and the electromagnet control circuit (3) is turned off; S7, performance testing: the taken-out sheet material (11) is tested for strengthening effect and surface quality performance. If the test result does not meet the preset requirements, the above steps are repeated to perform impact strengthening on the surface of the sheet material (11) again.

9. The electromagnetically driven sheet material surface impact toughening process according to claim 8, characterized in that: The diameter of the electromagnet core (2) is 100-500 mm, the wire diameter of the electromagnet coil (1) is 2 mm, the number of turns is 600-1500, the rated voltage is 20-50 V, the working current is 0.5 A-5 A, and the maximum suction force of the electromagnet assembly on the upper end of the outer wall of the high-alloy steel punch (7) is not less than 200 N, and the minimum suction force is not less than the sum of the weights of the high-alloy steel punch (7) and the copper ring (6).

10. The electromagnetically driven sheet material surface impact toughening process according to claim 8, characterized in that: The electromagnetic drive coil (5) has 4 layers in the coil height direction, 10 turns in a single layer, and is wound from a rectangular copper wire with a cross-sectional area of ​​2 mm*4 mm. The actual discharge voltage is 7-15 kV, and the discharge interval charging time is 10-20 s.

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