Groove member wick multi-pass current field assisted roll forming apparatus and method

Abstract

The application relates to a large-groove-piece wick multi-pass current field assisted roll forming device and method, which comprises: a first-pass roll forming device and a second-pass roll forming device, each of which comprises two supporting columns, a driving motor and a power supply; an upper roller is arranged in parallel above a lower roller, and the two ends of the upper roller and the two ends of the lower roller are rotationally connected with the two supporting columns; one end of the upper roller and one end of the lower roller are connected with the driving motor, and the other ends are connected with the power supply through connecting wires; the power supply, the upper roller, the groove piece and the lower roller form an electric circuit, the supporting columns and the driving motor are insulated from the electric circuit; a plurality of annular protrusions are arranged on the upper roller of the first-pass roll forming device in the axial direction; the lower roller of the first-pass roll forming device is a smooth roller; and the upper roller and the lower roller of the second-pass roll forming device are both smooth rollers. The application can realize the preparation of complex-shaped micro-grooves with large capillary force, and significantly reduces the preparation difficulty of high-performance wicks.

Description

Technical Field

[0001] The invention relates to the field of manufacturing technology of ultrathin heat pipe microstructure liquid absorber cores, and in particular to a multi-pass current field assisted roll forming device and method for liquid absorber cores of grooved thin plates. Background Technology

[0002] Miniaturization and integration of electronic components have become the main trend in the development of electronic devices. However, the heat flux density of highly integrated electronic components increases dramatically, generating localized high temperatures, which poses a significant challenge to thermal management, including heat transfer and heat dissipation, and severely restricts the improvement of electronic device performance. Studies have shown that the failure rate of electronic components is closely related to operating temperature; more than 55% of electronic device failures are caused by excessively high operating temperatures. For every 10°C increase, the device failure rate doubles, and the system reliability decreases by 50%. Traditional heat dissipation methods such as heat plates and heat pipes are insufficient to meet the thermal management requirements of high heat flux density devices. Efficient heat dissipation technology has become one of the bottlenecks in electronic devices and has attracted significant attention from the industry.

[0003] Phase change heat transfer devices utilize the principle of absorbing a large amount of heat during the phase change of the working fluid from liquid to gas to achieve heat transfer. They possess significantly higher thermal conductivity, several orders of magnitude higher than solid materials such as aluminum, copper, and graphene. Widely used in the heat dissipation of electronic components, they are gradually becoming the optimal heat dissipation solution for high heat flux density electronic products such as laptops and smartphones. Ultrathin heat pipes are a type of phase change heat transfer device. They utilize the capillary force of a wick to achieve the reflux of the liquid working fluid, enabling the transfer of a large heat flow under minute temperature differences without external energy or driving force. They exhibit extremely high thermal conductivity and have been widely applied in aerospace, electronics, power engineering, and biomedicine. The core and challenge of ultrathin heat pipes lies in the fabrication of a wick with high capillary force. Currently, etching technology is mainly used to fabricate microstructures such as microgrooves and support pillars. While this wick structure is simple, the process is lengthy, costly, and results in low capillary force. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the invention is to overcome the problems of simple cross-section of microgroove in existing ultrathin heat pipe liquid wicks and insufficient capillary force.

[0005] To solve the above-mentioned technical problems, on the one hand, the invention provides a multi-pass current field assisted roll forming device for liquid-absorbing cores of grooved parts, comprising:

[0006] The first and second roll forming devices both include a roll forming assembly, an upper roll, and a lower roll. The roll forming assembly includes two support columns, a drive motor, and a power supply. The upper roll is parallel to and above the lower roll, with both ends of the upper and lower rolls rotatably connected to the two support columns. One end of each roll is connected to the drive motor, and the other end is connected to the power supply via connecting wires. The power supply, upper roll, grooved component, and lower roll form an electrical circuit, with the support columns and drive motor insulated from the electrical circuit. The upper roll of the first roll forming device has multiple annular protrusions spaced along its axial direction. The lower roll of the first roll forming device is a smooth roll. Both the upper and lower rolls of the second roll forming device are smooth rolls.

[0007] The first-pass roll forming device is used to process and form multiple spaced rectangular microgrooves on the upper surface of the grooved part; the second-pass roll forming device is used to plastically deform the rectangular microgrooves to form... Microgrooves.

[0008] In one embodiment of the invention, there are two drive motors, and the upper roller and the lower roller are respectively connected to the two drive motors.

[0009] In one embodiment of the invention, the drive motor is connected to a controller for regulating the speed of the drive motor.

[0010] In one embodiment of the invention, the aspect ratio of the rectangular microgroove is greater than 1.

[0011] In one embodiment of the invention, the width of the rectangular microgroove is 100-150 μm, the depth of the microgroove is 80-200 μm, and the spacing between two connected microgrooves is 100-150 μm.

[0012] In one embodiment of the invention, the power supply is a digitally programmable pulse power supply used to change the current applied to the electrical circuit and the pulse length.

[0013] In one embodiment of the invention, the connecting wire is made of thick copper strip, and the cross-section of the thick copper strip is greater than 15mm. 2 .

[0014] In one embodiment of the invention, the ends of the upper and lower rollers are rotatably connected to the support column via insulating bushings.

[0015] In one embodiment of the invention, the ends of the upper and lower rollers are connected to a drive motor via an insulated coupling.

[0016] On the other hand, the invention provides a method for multi-pass current field-assisted roll forming of a grooved part for liquid-absorbing core, including:

[0017] In the first rolling process, the drive motor of the first rolling forming device controls the rotation of the upper and lower rollers to roll the grooved part fed between the upper and lower rollers, forming multiple rectangular micro-grooves on the upper surface of the grooved part.

[0018] In the second rolling process, the drive motor of the second rolling forming device controls the rotation of the upper and lower rollers to roll the grooved part after the first rolling process. Under the action of the current field and the rolling pressure, the rectangular microgrooves on the upper surface of the grooved part are deformed and formed. Microgrooves.

[0019] The above-mentioned technical solution of the invention has the following advantages compared with the prior art:

[0020] This invention discloses a multi-pass current-field assisted roll forming device and method for a grooved component's liquid-absorbing core. The first-pass roll forming device uses an upper roller with multiple annular protrusions for roll forming. The Joule heating effect of the current field increases the temperature of the microgroove component, reducing deformation resistance and thus improving the plastic deformation performance of the metal material, making it easier to roll form rectangular microgrooves with a large aspect ratio. Secondly, a second-pass roll forming device is used to roll the already formed rectangular microgrooves. This second-pass device requires no mold; it relies solely on the combined effects of the current field, temperature field, and stress field to deform the rectangular microgrooves. Microgrooves are formed to enhance the capillary force of the wick. Therefore, this embodiment, through the combined control of an external physical field and a deformation force field, can achieve complex shapes with high capillary force. The fabrication of microgrooves significantly reduces the difficulty of preparing high-performance liquid-absorbing cores. Furthermore, roll forming is a continuous forming process, making it highly suitable for mass production at low cost and high efficiency. Attached Figure Description

[0021] To make the invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0022] Figure 1 This is a schematic diagram of the structure of the first rolling forming device in a multi-pass current field assisted rolling forming device for a grooved part in a preferred embodiment of the present invention.

[0023] Figure 2 yes Figure 1 Cross-sectional view of the grooved part with rectangular microgrooves;

[0024] Figure 3 This is a schematic diagram of the structure of the second rolling forming device in the multi-pass current field assisted rolling forming device for the liquid suction core of a grooved part in a preferred embodiment of the present invention.

[0025] Figure 4 yes Figure 3 Prepared Cross-sectional view of a grooved component with microgrooves;

[0026] Figure 5 yes Figure 4 A magnified view of a portion of the image;

[0027] Figure 6 This is a simulation illustration. Figure 1 ;

[0028] Figure 7 This is a simulation illustration. Figure 2 .

[0029] Explanation of reference numerals in the accompanying drawings: 1. First-pass roll forming device; 2. Second-pass roll forming device; 3. Grooved part; 301. Rectangular micro-groove; 302. Microgrooves; 303, substrate; 304, middle position of side wall; 100, upper roller; 200, lower roller; 300, support column; 400, drive motor; 500, power supply; 600, connecting wire; 700, base; 800, controller; 900, insulated coupling; 1000, insulated bushing. Detailed Implementation

[0030] The invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the invention, but the embodiments are not intended to limit the invention.

[0031] Reference Figures 1-4 As shown, the invention provides a multi-pass current field-assisted roll forming device for a grooved part's liquid-absorbing core, comprising:

[0032] The first-pass roll forming device 1 and the second-pass roll forming device 2 both include a roll forming assembly, an upper roll 100, and a lower roll 200. The roll forming assembly includes two support columns 300, a drive motor 400, and a power supply 500. The upper roll 100 is arranged parallel above the lower roll 200, and both ends of the upper roll 100 and the lower roll 200 are rotatably connected to the two support columns 300. One end of both the upper roll 100 and the lower roll 200 is connected to the drive motor 400, and the other end is connected to... The power supply 500 is connected via connecting wire 600; the power supply 500, upper roller 100, grooved part 3, and lower roller 200 form an electrical circuit (i.e., form a current field), and the support column 300 and drive motor 400 are insulated from the electrical circuit; the upper roller 100 of the first-pass roll forming device 1 has multiple annular protrusions spaced along its axial direction; the lower roller 200 of the first-pass roll forming device 1 is a smooth roller; both the upper roller 100 and the lower roller 200 of the second-pass roll forming device 2 are smooth rollers;

[0033] The first-pass roll forming device 1 is used to process and form multiple spaced rectangular microgrooves 301 on the upper surface of the grooved part 3; the second-pass roll forming device 2 is used to plastically deform the rectangular microgrooves 301 to form Microgrooves 302 ( The micro-groove 302 refers to the groove width gradually increasing along the direction from the lower surface to the upper surface of the groove part 3.

[0034] In some embodiments, the roll forming assembly further includes a base 700, which is fixed to the top of the two support columns 300.

[0035] The method of roll forming using a multi-pass current field assisted roll forming device with a liquid-absorbing core of grooved part 3 includes:

[0036] In the first rolling process, the drive motor 400 of the first rolling forming device 1 controls the rotation of the upper roller 100 and the lower roller 200 to roll the grooved part 3 fed between the upper roller 100 and the lower roller 200, forming multiple rectangular microgrooves 301 on the upper surface of the grooved part 3. When the current flows through the grooved part 3, the grooved part 3 has a large resistance, which generates a Joule heating effect, that is, the temperature of the grooved part 3 increases, the deformation resistance decreases, and the plastic forming ability increases, thus making it easier to roll form rectangular microgrooves 301 with a large depth-to-width ratio, completing the first forming process. The amount of plastic deformation of the grooved part 3 is controlled by the upper roller 100.

[0037] In the second rolling process, the drive motor 400 of the second rolling forming device 2 controls the rotation of the upper roller 100 and the lower roller 200 to roll the grooved part 3 after the first rolling process. Under the action of the current field and the rolling pressure, the rectangular microgrooves 301 on the upper surface of the grooved part 3 are deformed and formed. Microgrooves 302. Due to the microgrooves ( The rectangular microgroove 302 has a relatively small size, and under the action of roll forming force, the sidewalls of the rectangular microgroove 301 undergo significant deformation. (See also...) Figure 5 The upper end face of the microgroove sidewall has contact friction with the roller, and the lower end is constrained by the base 303 of the groove component 3. Therefore, plastic deformation mainly occurs at the middle position 304 of the microgroove sidewall. Simultaneously, when a current field is applied, the upper and lower end faces of the microgroove sidewall in contact with the roller and base 303 dissipate heat quickly, resulting in lower temperatures. The middle part of the microgroove has a relatively higher temperature, making it more prone to plastic deformation. Consequently, the deformation of the microgroove sidewall flows and bulges towards the interior of the microgroove, causing the cross-section of the microgroove to deform from a rectangle. Shape. Thus, under conditions without molds, a large capillary force can be prepared. 302 pieces of microgrooves.

[0038] See Figure 6Using this application, simulations were conducted on the blank shape under different reduction amounts during the first roll forming process, where: (a) 0mm, (b) 0.025mm, (c) 0.05mm, and (d) 0.06mm. As can be seen from the figure, (b) shows the best effect.

[0039] See Figure 7 The equivalent strain distribution was simulated using this application under different compression amounts, where: (a) the compression amount was 0 mm; (b) the compression amount was 0.025 mm; (c) the compression amount was 0.05 mm; and (d) the compression amount was 0.06 mm. As can be seen from the figure, (d) has the best effect.

[0040] because The capillary force of the liquid-absorbing core of the microgroove 302 is large, but in some comparative embodiments, it is performed on a large, thin-walled groove component 3. The microgroove 302 is relatively difficult to process.

[0041] Specifically, in this embodiment, the first-pass roll forming device 1 uses an upper roller 100 with multiple annular protrusions for roll forming. The Joule heating effect of the current field is used to raise the temperature of the microgroove part 3, reducing deformation resistance and thus improving the plastic deformation performance of the metal material. This makes it easier to roll form a rectangular microgroove 301 with a large aspect ratio. Next, the second-pass roll forming device 2 is used to roll form the already formed rectangular microgroove 301. This device requires no mold and relies solely on the combined effects of the current field, temperature field, and stress field to deform the rectangular microgroove 301 into... Microgrooves 302 are formed to enhance the capillary force of the wick. Therefore, this embodiment, through the combined control of an external physical field and a deformation force field, can achieve complex shapes with high capillary force. The fabrication of the microgrooves 302 significantly reduces the difficulty of preparing high-performance liquid-absorbing cores. Furthermore, roll forming is a continuous forming process, highly suitable for mass production at low cost and high efficiency.

[0042] This embodiment solves the problems of simple microgroove cross-section and insufficient capillary force in existing ultrathin heat pipe wicks.

[0043] Furthermore, there are two drive motors 400, with the upper roller 100 and lower roller 200 respectively connected to the two drive motors 400. Specifically, the two drive motors 400 control the upper roller 100 and lower roller 200 respectively, enabling asynchronous rolling (the upper roller 100 and lower roller 200 rotate at different speeds), thereby controlling the flatness of the grooved part 3 processing section. In some embodiments, the drive motors 400 are high-power motors, such as 20kW motors, with continuously adjustable speeds.

[0044] Furthermore, the drive motor 400 is connected to a controller 800 for regulating the speed of the drive motor 400. In some embodiments, when there are two drive motors 400, the two drive motors 400 can share one controller 800. Specifically, the speed of the drive motor 400 can be controlled by the controller 800 to achieve automated regulation.

[0045] Furthermore, the aspect ratio of the rectangular microgroove 301 is greater than 1. The width of the rectangular microgroove 301 is 100-150 μm, the groove depth is 80-200 μm, and the spacing between two adjacent microgrooves is 100-150 μm.

[0046] Furthermore, the power supply 500 is a digitally programmable pulse power supply 500, used to change the current applied to the electrical circuit and the pulse length, thereby adjusting the power of the power supply 500 per unit time, controlling the temperature field of the deformation area, and thus adjusting the rectangular microgroove 301 or The machining accuracy of the microgrooves 302 and the magnitude of the deformation force during machining are crucial (excessive deformation force will cause difficulty in rotating the upper roller 100 and lower roller 200; insufficient deformation force will result in a small amount of microgroove machining, thus affecting the capillary force of the liquid-absorbing core). The specific parameters of the high-power power supply 500 are selected based on parameters such as the dimensions of the grooved part 3. For example, when performing multi-pass roll forming on a grooved part 3 with a thickness of 0.1-2mm and a width of 20-100mm, the main technical parameters of the power supply 500 are 0-36V, current 200-10000A, output frequency 1-5kHz, and pulse width 2-500μs.

[0047] Furthermore, the connecting wire 600 uses thick copper strip, and the cross-section of the thick copper strip is greater than 15mm. 2 This embodiment can reduce the influence of the resistance of the connecting wire 600 itself.

[0048] Furthermore, the ends of the upper roller 100 and the lower roller 200 are rotatably connected to the support column 300 via an insulating bushing 1000.

[0049] Furthermore, the ends of the upper roller 100 and the lower roller 200 are connected to the drive motor 400 via an insulated coupling 900.

[0050] Furthermore, both the upper roller 100 and the lower roller 200 are made of die steel and ground.

[0051] Furthermore, the grooved part 3 is made of aluminum alloy or copper alloy. For example, the grooved part 3 is made of 5-series aluminum alloy. Specifically, aluminum alloy and copper alloy have high thermal conductivity.

[0052] The roll forming process of this application is as follows:

[0053] (1) First pass roll forming of rectangular microgrooves 301: According to the thickness of the groove part 3 and the depth of the microgrooves, adjust the gap between the upper roller 100 and the lower roller 200 of the first pass roll forming device 1; start the two drive motors 400, and the speed of the two drive motors 400 should have a certain speed difference, for example, one is 5 rpm and the other is 6 rpm. Then, turn on the power supply 500, and then use insulated tweezers to clamp the aluminum alloy sheet (i.e., the groove part 3 blank) and feed it between the upper and lower rollers. Under the interlocking action of the upper and lower rollers, the groove part 3 continuously enters between the two rollers. Under the action of the upper roller 100, multiple rectangular microgrooves 301 are formed on the upper surface of the groove part 3. After forming, the size of the rectangular microgrooves 301 is measured using a super depth-of-field microscope, etc. If there is a difference from the design value, adjust the gap, speed, current parameters, etc. of the two rollers (upper and lower rollers) to continue roll forming until the size of the rectangular microgrooves 301 meets the standard. After the rectangular microgroove 301 is formed, turn off the power supply 500 and the drive motor 400.

[0054] (2) Second roll forming Microgrooves 302: Using the grooved part 3 with rectangular microgrooves 301 formed in the first pass, a second roll forming is performed. At this time, the upper roller 100 is a smooth roller. The gap between the two rollers (upper and lower rollers) is set according to the deformation amount of the microgrooves in this process. Then, the drive motor 400 is turned on and the speed is set, and the power supply 500 is turned on. Using insulated tweezers, the grooved part 3 with rectangular microgrooves 301 is held and placed between the two rollers. Under the combined action of the current field and the roller pressure, the rectangular microgrooves 301 on the upper surface of the grooved part 3 deform. The sidewalls of the rectangular microgrooves 301 deform into an irregular "drum shape," while the rectangular microgrooves 301 themselves deform into... Cross-sectional shape. Based on the shape after forming. The difference between the cross-sectional shape and the design value was investigated, and adjustments were made to the gap between the two rollers, the rotational speed, and the current parameters until... The dimensions of the microgroove 302 meet the standards.

[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A multi-pass current field-assisted roll forming device for a grooved part's liquid-absorbing core, characterized in that: include: The first and second roll forming devices both include a roll forming assembly, an upper roll, and a lower roll. The roll forming assembly includes two support columns, a drive motor, and a power supply. The upper roll is arranged parallel above the lower roll, and both ends of the upper and lower rolls are rotatably connected to the two support columns. One end of each of the upper and lower rolls is connected to the drive motor, and the other end is connected to the power supply via connecting wires. The power supply, the upper roll, the grooved component, and the lower roll form an electrical circuit, and the support columns and drive motor are insulated from the electrical circuit. The upper roll of the first roll forming device has multiple annular protrusions spaced along its axial direction. The lower roll of the first roll forming device is a smooth roll. Both the upper and lower rolls of the second roll forming device are smooth rolls. The first-pass roll forming device is used to process and form a plurality of spaced rectangular microgrooves on the upper surface of the grooved part; the second-pass roll forming device is used to plastically deform the rectangular microgrooves to form... The microgroove is shaped like a "V" shape. The upper end of the microgroove sidewall has contact friction with the roller, while the lower end is constrained by the substrate of the grooved component. Plastic deformation mainly occurs in the middle of the microgroove sidewall. Simultaneously, when an electric field is applied, the upper and lower end faces of the microgroove sidewall in contact with the roller and substrate dissipate heat quickly, resulting in lower temperatures. The middle part of the microgroove has a relatively higher temperature, causing the deformation of the microgroove sidewall to flow and bulge inwards, thus deforming the cross-section of the microgroove from a rectangle to a "V" shape. "shape.

2. The multi-pass current field assisted roll forming device for the liquid-absorbing core of the grooved part according to claim 1, characterized in that: There are two drive motors, and the upper roller and the lower roller are respectively connected to the two drive motors.

3. The multi-pass current field assisted roll forming device for the liquid-absorbing core of the grooved part according to claim 1, characterized in that: The drive motor is connected to a controller for regulating the speed of the drive motor.

4. The multi-pass current field assisted roll forming device for the liquid-absorbing core of the grooved part according to claim 1, characterized in that: The aspect ratio of the rectangular microgroove is greater than 1.

5. The multi-pass current field assisted roll forming device for the liquid-absorbing core of the grooved part according to claim 4, characterized in that: The width of the rectangular microgroove is 100-150μm, and the depth of the microgroove is 80-200μm; The spacing between two connected microgrooves is 100-150 μm.

6. The multi-pass current field assisted roll forming device for the liquid-absorbing core of the grooved part according to claim 1, characterized in that: The power supply is a digitally programmable pulse power supply, used to change the current applied to the electrical circuit and the pulse length.

7. The multi-pass current field assisted roll forming device for the liquid-absorbing core of the grooved part according to claim 1, characterized in that: The connecting wire is made of thick copper strip, and the cross-section of the thick copper strip is greater than 15mm. 2 .

8. The multi-pass current field assisted roll forming device for the liquid-absorbing core of the grooved part according to claim 1, characterized in that: The ends of the upper roller and the lower roller are rotatably connected to the support column via insulating bushings.

9. The multi-pass current field assisted roll forming device for the liquid-absorbing core of the grooved part according to claim 1, characterized in that: The ends of the upper roller and the lower roller are connected to the drive motor via insulated couplings.

10. A forming method using a multi-pass current field-assisted roll forming apparatus for a grooved core as described in any one of claims 1-9, characterized in that: include: In the first rolling process, the drive motor of the first rolling forming device controls the rotation of the upper and lower rollers to roll the grooved part fed between the upper and lower rollers, forming multiple rectangular micro-grooves on the upper surface of the grooved part. In the second rolling process, the drive motor of the second rolling forming device controls the rotation of the upper and lower rollers to roll the grooved part after the first rolling process. Under the action of the current field and the rolling pressure, the rectangular microgrooves on the upper surface of the grooved part deform to form... "Shaped micro-grooves".

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