Electric field assisted large area microstructure roll forming device

Abstract

The present application belongs to the technical field of roll imprinting process, and particularly relates to a large-area microstructure roll forming device assisted by electric field. The device comprises a servo unwinder, a leveler, a first toothed roller, a stress relieving machine, a strip placing machine, a second toothed roller, a strip recycling unit and a leveler and cutting compound machine arranged in sequence. The servo unwinder is used to output a metal strip. The first toothed roller is used to roll form a semicircular groove on the surface of the metal strip. The strip placing machine is used to lay a limiting strip in the semicircular groove. The second toothed roller is used to roll the semicircular groove through the limiting strip to obtain an inverted arch-shaped microstructure groove. The roll forming stations of the first and second toothed rollers are equipped with electric field assisted generating assemblies. The strip recycling unit is used to automatically peel and recycle the limiting strip. The leveler and cutting compound machine is used to level and cut the metal strip. The present application improves the current distribution state by means of partition discharge regulation and control and a recyclable strip structure, strengthens the crack inhibition effect, reduces the matching cost and has good forming quality stability.

Description

Technical Field

[0001] This invention belongs to the field of roller embossing technology, specifically relating to an electric field-assisted large-area microstructure roller forming device. Background Technology

[0002] Titanium alloys are often difficult to machine, exhibiting poor plasticity at room temperature and a tendency to develop microcracks during forming. Hot stamping processes have a narrow temperature range, making them highly susceptible to microcrack defects during conventional roll forming of microstructures with an aspect ratio greater than 6. While existing solutions incorporate ultrasonic, electrical pulse, and prestress-assisted technologies, they still have several shortcomings: prestress control requires an additional leveling machine, resulting in large strain at the roll forming contact surface and limited crack suppression; traditional ultrasonic transducers require ceramic plates and pre-tightening bolts, leading to complex structures; conventional electrical pulses suffer from the skin effect, preventing the current from being effectively targeted to the bottom of the microstructure groove, resulting in significant workpiece springback and twinning defects, poor plastic forming control, and difficulty in achieving stable mass production roll forming of high aspect ratio titanium alloy microstructures. Summary of the Invention

[0003] To address the aforementioned problems, the present invention aims to provide an electric field-assisted large-area microstructure roll forming device to overcome the technical problems of poor plasticity of titanium alloys and the easy generation of microcracks during high aspect ratio microstructure roll forming. It also solves the drawbacks of various existing forming assistance schemes, such as complex structure, weak crack suppression effect, and interference of electric pulse skin effect with forming quality, thereby achieving the goal of stable mass production roll forming of high aspect ratio microstructures of titanium alloys.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides an electric field-assisted large-area microstructure roll forming device, comprising a servo unwinding machine, a leveling machine, a first toothed roller machine, a stress-relieving machine, a pressure strip placement machine, a second toothed roller machine, a pressure strip recycling unit, and a leveling and cutting composite machine arranged sequentially along the conveying path of a metal strip; the servo unwinding machine is used for continuously unwinding and outputting metal strips; the first toothed roller machine is used for roll forming semi-circular grooves on the surface of the metal strip; the stress-relieving machine is used for heat treatment of the metal strip; the pressure strip placement machine is used for laying crescent-shaped limiting pressure strips into the semi-circular grooves on the surface of the metal strip; the second toothed roller machine rolls the semi-circular grooves through the limiting pressure strips, causing the semi-circular grooves to plastically deform into inverted arch-shaped microstructure grooves; both the first and second toothed roller machines are equipped with electric field auxiliary generating components for applying an auxiliary electric field; the pressure strip recycling unit is used for automatically peeling off and recycling the limiting pressure strips after the inverted arch-shaped microstructure grooves are formed; the leveling and cutting composite machine is used for leveling and cutting the formed metal strip.

[0006] The first and second toothed roller machines have the same structure, both including a smooth roller disposed below the metal strip and an arc toothed roller disposed above the metal strip. Both the smooth roller and the arc toothed roller are power-driven active rollers. The outer surface of the arc toothed roller is provided with multiple rounded teeth along the circumference, and there is a tooth root arc between two adjacent rounded teeth. A metal sheet is embedded at the tooth tip of each rounded tooth.

[0007] The cross-section of the roundness tooth is a semi-circular structure; the metal sheet is the same length as the roundness tooth, and its width extends radially to the center of the roundness tooth; the two ends of the metal sheet in the width direction are arc structures, and the outer end face is coplanar with the outer surface of the roundness tooth.

[0008] The metal sheet is made of high-speed steel; the roundness teeth and tooth root arcs are made of zirconium oxide insulating ceramic.

[0009] The metal sheet and the optical roller serve as the two poles of the electrical pulse, respectively.

[0010] The auxiliary DC pulse parameters applied by the electric field auxiliary generating component are: current 1450A~1790A, pulse frequency 300±10Hz, and voltage 1.5V.

[0011] The circular arc toothed roller rolls the metal strip to process five microstructure grooves in sequence. No discharge is performed in the elastic deformation range of the first microstructure groove. Discharge is applied during the formation of the second to fourth microstructure grooves. Discharge is terminated after the fifth microstructure groove is formed.

[0012] The limiting pressure strip is made of tungsten carbide; the upper concave surface of the limiting pressure strip is adapted to the roundness teeth to form a limiting pressure surface, and the lower convex surface of the limiting pressure strip serves as a pressure surface that causes the semi-circular groove to deform.

[0013] The strip recycling unit includes a bending roller machine and a strip recycling machine, wherein the bending roller machine is used to elastically bend and peel off the limiting strip from the metal strip; and the strip recycling machine is used to recycle the strip.

[0014] The bending roller machine includes a front roller, a middle roller, and a rear roller arranged in sequence. The front roller and the rear roller are both located above the metal strip, and the middle roller is located below the metal strip. The top of the middle roller is higher than the bottom of the front roller and the rear roller, so that the metal strip completes three elastic bends. When the metal strip travels to the position of the middle roller, the clamping constraint of the inverted arch-shaped microstructure groove on the limiting pressure strip is released.

[0015] The present invention has the following beneficial effects and advantages:

[0016] 1. Precise flow control in electroplastic forming improves molding quality: This invention uses electrically assisted microstructure roller tooth pressing to achieve electroplastic forming of materials, controlling the local current peak density in the plastic deformation area to 2.8±2A / mm2, which can significantly suppress workpiece springback, reduce the amount of plastic springback in roller tooth forming by 27%, and at the same time greatly reduce the probability of material twinning.

[0017] 2. On-demand pulse current matching servo roller pressing avoids skin effect and saves energy: The electric assisted microstructure toothed roller forming process for 502 high-speed steel sheet adopts on-demand pulse current power supply, which can effectively eliminate the skin effect present in the existing conventional process; the current control scheme is linked and matched with the roller tooth rotation servo system, and releases current only during the plastic deformation stage of the material, avoiding discharge in the elastic deformation range, which has the advantages of energy saving and environmental protection.

[0018] 3. Crescent-shaped tungsten carbide structure optimizes roller life, and orthogonal arrangement reduces fatigue cracking risk: The addition of crescent-shaped tungsten carbide wear-resistant strips to the rollers effectively extends the service life of the microstructure roller teeth. From a materials mechanics perspective: If the microstructure extension direction is parallel to the conveying length of the plate, the compressive stress between adjacent roller teeth is significantly higher than in the arrangement where the microstructure length direction is orthogonal to the conveying length in this invention. Parallel arrangements are more prone to fatigue-induced microcracks. The orthogonal arrangement in this invention reduces inter-tooth compressive stress, decreases microcrack initiation, and improves roller durability.

[0019] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0022] Figure 1 This is an isometric view of an electric field-assisted large-area microstructure roll forming device according to the present invention.

[0023] Figure 2 This is a side view of an electric field-assisted large-area microstructure roll forming device according to the present invention;

[0024] Figure 3 for Figure 2 Enlarged view of a portion of point A in the middle;

[0025] Figure 4 for Figure 2 A magnified view of a portion of point B in the middle.

[0026] In the diagram: 1. Metal coil; 2. Metal strip; 201. First microstructure groove; 202. Second microstructure groove; 203. Third microstructure groove; 204. Fourth microstructure groove; 205. Fifth microstructure groove; 206. Semicircular groove; 207. Inverted arch-shaped microstructure groove; 3. Servo unwinding machine; 4. Leveling machine; 5. First toothed roller machine; 501. First circular arc toothed roller; 502. Roundness tooth; 503. Tooth root arc; 504. Metal sheet; 6. Stress relief machine; 7. Pressure strip placement machine; 8. Second toothed roller machine; 801. Second circular arc toothed roller; 9. Bending roller machine; 901. Front side roller; 902. Middle roller; 903. Rear side roller; 10. Pressure strip recycling machine; 11. Leveling and cutting composite machine; 12. Limiting pressure strip. Detailed Implementation

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0029] See Figures 1 to 4As shown, this invention provides an electric field-assisted large-area microstructure roll forming device, comprising a servo unwinding machine 3, a leveling machine 4, a first toothed roller mill 5, a stress-relieving machine 6, a strip placement machine 7, a second toothed roller mill 8, a strip recycling unit, and a leveling and cutting composite machine 11 arranged sequentially along the conveying path of a metal strip 2; the servo unwinding machine 3 is used for continuously unwinding the metal coil 1 to output the metal strip 2; the first toothed roller mill 5 is used for roll forming a semi-circular groove 206 on the surface of the metal strip 2; the stress-relieving machine 6 is used for heat treating the metal strip 2; and the strip placement machine 7 is used for laying crescent-shaped grooves into the semi-circular grooves 206 on the surface of the metal strip 2. The limiting strip 12 of the cross section, the second toothed roller machine 8 rolls the semi-circular groove 206 through the limiting strip 12, so that the semi-circular groove 206 is plastically deformed into an inverted arch-shaped microstructure groove 207, the length direction of the inverted arch-shaped microstructure groove 207 is orthogonal to the conveying direction of the metal strip 2; the rolling station of the first toothed roller machine 5 and the second toothed roller machine 8 are both equipped with electric field auxiliary generating components for applying auxiliary electric field; the strip recycling unit is used to automatically peel off and recycle the limiting strip 12 after the inverted arch-shaped microstructure groove 207 is formed; the leveling and cutting composite machine 11 is used to level and cut the formed metal strip 2.

[0030] See Figures 1 to 4 As shown, the first toothed roller machine 5 and the second toothed roller machine 8 have the same structure, both including a smooth roller disposed below the metal strip 2 and an arc toothed roller disposed above the metal strip 2. Both the smooth roller and the arc toothed roller are power-driven active rollers. The outer surface of the arc toothed roller is provided with a plurality of roundness teeth 502 along the circumference. Between two adjacent roundness teeth 502 is a tooth root arc 503. A metal sheet 504 is embedded at the tooth tip of each roundness tooth 502. The metal sheet 504 and the smooth roller serve as the two poles of the electrical pulse, respectively.

[0031] Specifically, the cross-section of the roundness tooth 502 is a semi-circular structure; the metal sheet 504 is the same length as the roundness tooth 502, and its width extends radially to the center of the roundness tooth 502; the two ends of the metal sheet 504 in the width direction are arc structures, and the outer end face is coplanar with the outer surface of the roundness tooth 502.

[0032] Preferably, the metal sheet 504 is made of high-speed steel; the rounded teeth 502 and the tooth root arc 503 are made of zirconia insulating ceramic. The auxiliary DC pulse parameters applied by the electric field auxiliary generating component are: current 1450A~1790A, pulse frequency 300±10Hz, and voltage 1.5V. The metal sheet 504 has fifty-two electrode points, and the point layout matches the actual installation process requirements.

[0033] Specifically, the circular arc toothed roller rolls the metal strip 2 to process five microstructure grooves in sequence, namely the first microstructure groove 201, the second microstructure groove 202, the third microstructure groove 203, the fourth microstructure groove 204, and the fifth microstructure groove 205, which are formed by sequential plastic deformation. No discharge is performed in the elastic deformation range of the first microstructure groove 201, discharge is applied in the stage of forming the second to fourth microstructure grooves, and the discharge is terminated after the fifth microstructure groove 205 is formed.

[0034] In this embodiment, the first toothed roller machine 5 includes a first arc toothed roller 501, with eighty-one round teeth 502 arranged circumferentially on the first arc toothed roller 501; the second toothed roller machine 8 includes a second arc toothed roller 801. During operation, the second arc toothed roller 801 abuts against the crescent-shaped limiting pressure strip 12 to carry out subsequent rolling operations, driving the semi-circular groove 206 of the metal strip 2 to undergo plastic deformation and form an inverted arch-shaped microstructure groove 207.

[0035] Preferably, the metal strip 2 is a titanium alloy of grade TA1. The limiting pressure strip 12 is made of tungsten carbide with excellent conductivity, and its hardness can reach 12 to 15 times that of titanium alloy TC1. The upper concave surface of the limiting pressure strip 12 is adapted to the roundness teeth 502 to form a limiting pressure bearing surface, and the lower convex surface of the limiting pressure strip 12 serves as the pressure application working surface. The downward pressure drives the semi-circular groove 206 of the metal strip 2 to undergo plastic deformation, and finally obtains the inverted arch-shaped microstructure groove 207.

[0036] In this embodiment, the leveling machine 4 is equipped with multiple sets of rollers for rolling and leveling the metal strip 2. This invention employs a multi-stage rolling process to process microstructures, with the length direction of the microstructure's groove orthogonal to the conveying direction of the metal strip 2. This embodiment only lists two stages of rolling as an example; extending the rolling process to include more stages using conventional engineering methods also falls within the scope of this invention. A stress-relieving machine 6 is placed between adjacent rolling stages. The stress-relieving process uses recrystallization annealing for heating, preferably with the heating temperature controlled at 697±5℃.

[0037] See Figure 1 and Figure 2 As shown, in an embodiment of the present invention, the strip recycling unit includes a bending roller machine 9 and a strip recycling machine 10, wherein the bending roller machine 9 is used to elastically bend and peel off the limiting strip 12 of the metal strip 2; the strip recycling machine 10 is used to recycle the strip.

[0038] Specifically, the bending roller machine 9 includes a front roller 901, a middle roller 902, and a rear roller 903 arranged in sequence. The front roller 901 and the rear roller 903 are both located above the metal strip 2, and the middle roller 902 is located below the metal strip 2. The top of the middle roller 902 is higher than the bottom of the front roller 901 and the rear roller 903, so that the metal strip 2 completes three elastic bends. When the metal strip 2 travels to the position of the middle roller 902, the clamping constraint of the inverted arch-shaped microstructure groove 207 on the limiting pressure strip 12 is released.

[0039] After initial forming, the limiting strip 12 is clamped and fixed by the rebound stress generated by the inverted arch-shaped microstructure groove 207. The metal strip 2 undergoes three elastic bending deformations in sequence through the front roller 901, the middle roller 902, and the rear roller 903. The microstructure rebound clamping force on the limiting strip 12 in the middle roller 902 section is released, thus allowing the limiting strip 12 to be easily removed. Finally, the leveling and cutting composite machine 11 levels the metal strip 2 with the inverted arch-shaped microstructure groove 207 and cuts it to the specified length according to the process settings.

[0040] This invention reduces roller tooth springback by 27% and decreases the probability of twinning by controlling the local current peak density in the plastic deformation zone to 2.8±2A / mm2; it eliminates the skin effect by using on-demand pulse current adapted to 502 high-speed steel metal sheets; the linkage roller tooth servo system discharges only in the plastic stage, saving energy and reducing consumption; the crescent-shaped tungsten carbide strips improve the service life of the roller teeth; and the orthogonal conveying length arrangement of the microstructure can reduce inter-tooth compressive stress and reduce fatigue cracking microcracks.

[0041] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An electric field-assisted large-area microstructure roll forming device, characterized in that, The system includes a servo unwinding machine (3), a leveling machine (4), a first toothed roller mill (5), a stress-relieving machine (6), a strip placement machine (7), a second toothed roller mill (8), a strip recycling unit, and a leveling and cutting composite machine (11) arranged sequentially along the conveying path of the metal strip (2); the servo unwinding machine (3) is used to continuously unwind the metal coil (1) to output the metal strip (2); the first toothed roller mill (5) is used to roll-form a semi-circular groove (206) on the surface of the metal strip (2); the stress-relieving machine (6) is used to heat-treat the metal strip (2); and the strip placement machine (7) is used to roll-form a semi-circular groove (206) on the surface of the metal strip (2). (206) A crescent-shaped limiting strip (12) is laid inside. The second toothed roller machine (8) rolls the semi-circular groove (206) through the limiting strip (12) to plastically shape the semi-circular groove (206) into an inverted arch-shaped microstructure groove (207). The rolling stations of the first toothed roller machine (5) and the second toothed roller machine (8) are equipped with electric field auxiliary generating components for applying auxiliary electric fields. The strip recycling unit is used to automatically peel off and recycle the limiting strip (12) after the inverted arch-shaped microstructure groove (207) is formed. The leveling and cutting composite machine (11) is used to level and cut the formed metal strip (2).

2. The electric field-assisted large-area microstructure roll forming device according to claim 1, characterized in that, The first toothed roller machine (5) and the second toothed roller machine (8) have the same structure, both including a smooth roller disposed below the metal strip (2) and an arc toothed roller disposed above the metal strip (2). Both the smooth roller and the arc toothed roller are power-driven active rollers. The outer surface of the arc toothed roller is provided with a plurality of roundness teeth (502) along the circumferential direction. There is a tooth root arc (503) between two adjacent roundness teeth (502). A metal sheet (504) is embedded at the tooth tip of each roundness tooth (502).

3. The electric field-assisted large-area microstructure roll forming device according to claim 2, characterized in that, The cross-section of the roundness tooth (502) is a semi-circular structure; the metal sheet (504) is the same length as the roundness tooth (502) and its width extends radially to the center of the roundness tooth (502); the two ends of the width direction of the metal sheet (504) are arc structures, and the outer end face is coplanar with the outer surface of the roundness tooth (502).

4. The electric field-assisted large-area microstructure roll forming device according to claim 2, characterized in that, The metal sheet (504) is made of high-speed steel; the roundness teeth (502) and the root arc (503) are made of zirconium oxide insulating ceramic.

5. The electric field-assisted large-area microstructure roll forming device according to claim 2, characterized in that, The metal sheet (504) and the optical roller serve as the two poles of the electrical pulse, respectively.

6. The electric field-assisted large-area microstructure roll forming device according to claim 5, characterized in that, The auxiliary DC pulse parameters applied by the electric field auxiliary generating component are: current 1450A~1790A, pulse frequency 300±10Hz, and voltage 1.5V.

7. The electric field-assisted large-area microstructure roll forming device according to claim 2, characterized in that, The circular arc toothed roller rolls the metal strip (2) to process five micro-structure grooves in sequence. No discharge is performed in the elastic deformation range of the first micro-structure groove. Discharge is applied in the second to fourth micro-structure grooves. Discharge is terminated after the fifth micro-structure groove is formed.

8. The electric field-assisted large-area microstructure roll forming device according to claim 2, characterized in that, The limiting pressure strip (12) is made of tungsten carbide; the upper concave surface of the limiting pressure strip (12) is adapted to the roundness tooth (502) to form a limiting pressure surface, and the lower convex surface of the limiting pressure strip (12) serves as the pressure surface that causes the semi-circular groove (206) to deform.

9. The electric field-assisted large-area microstructure roll forming device according to claim 1, characterized in that, The strip recycling unit includes a bending roller machine (9) and a strip recycling machine (10), wherein the bending roller machine (9) is used to elastically bend and peel off the limiting strip (12) from the metal strip (2); the strip recycling machine (10) is used to recycle the strip recycling machine (10).

10. The electric field-assisted large-area microstructure roll forming device according to claim 1, characterized in that, The bending roller machine (9) includes a front roller (901), a middle roller (902) and a rear roller (903) arranged in sequence. The front roller (901) and the rear roller (903) are both located above the metal strip (2), and the middle roller (902) is located below the metal strip (2). The top of the middle roller (902) is higher than the bottom of the front roller (901) and the rear roller (903), so that the metal strip (2) completes three elastic bends. When the metal strip (2) travels to the position of the middle roller (902), the clamping constraint of the inverted arch-shaped microstructure groove (207) on the limiting pressure strip (12) is released.

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