Ultrasonic / laser composite multi-scale integrated forming process method and device for special-shaped fins

Abstract

The invention discloses a special-shaped fin ultrasonic / laser composite multi-scale integrated forming process method and device.The method comprises the steps that S1, a to-be-formed fin is pretreated to obtain a to-be-machined fin, S2, in the fin laser scanning process, a clamp provided with an interdigital transducer is used for conducting acoustic surface waves to prepare a functional surface micro-texture, and S3, the functional surface micro-texture is subjected to ultrasonic / laser composite multi-scale integrated forming. And S3, laser bending forming is conducted through a turnover clamp, and the specific treatment includes the steps that (1) according to the structure of the special-shaped fin, front and back scanning tracks are designed; and (2) process parameters are determined, different areas of the heating wire are discretized, and accurate forming is achieved by adopting an energy regulation and control strategy. According to the multi-scale special-shaped fin forming method, integrated forming of the multi-scale special-shaped fin without secondary disassembly is achieved, and the obtained multi-scale special-shaped fin can improve the service performance of a micro-channel fin, for example, heat and mass transfer is enhanced, and the contact area and adhesive force of a catalyst are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal sheet processing and forming, and in particular relates to a special-shaped fin ultrasonic / laser composite multi-scale integrated forming process method and device. Background Art

[0002] Fin structures (such as fuel cell bipolar plates, reactor flow plates, heat exchanger fins, etc.) are core components in emerging fields such as new energy vehicles, hydrogen energy equipment, and thermal management systems, and they play key roles in heat and mass transfer, catalytic loading, directional flow guidance, and structural support. Under the demand for high efficiency and high energy density, the fin structure is showing a trend of miniaturization, specialization, and multi-scale development. For example, high-efficiency heat exchange fins are designed with surface micro-functional structures, microreactor flow plates are designed with flow channels with different porosity structures at the inlet and outlet, and the 3D flow channel structure of fuel cell bipolar plates is designed with a side convex structure.

[0003] The production of multi-scale fins usually adopts independent processing and step-by-step forming methods because it involves weaving forming and bending processes. Generally, macro flow channels are first produced by stamping, and then surface texturing technology is used to produce surface micro textures, such as electrolytic machining technology, electrospark machining technology, abrasive gas jet technology, etc. Due to problems such as uneven force and scale effect, the use of traditional forming processes often leads to problems such as rebound wrinkling, poor uniformity, and dimensional deviation. At the same time, the design and manufacture of special-shaped fins are prone to higher mold opening costs and longer production cycles. Due to the problems of complicated processes, difficult forming, and many defects, the forming quality and pass rate of multi-scale fins are seriously affected.

[0004] Laser manufacturing has the advantages of non-contact, high efficiency, green, and selective. Laser melting is a scientific technology that improves the wear resistance and corrosion resistance of parts and the surface morphology without changing the material properties. It can both "control the shape" and "control the properties". Laser bending technology is a mold-free, highly flexible bending technology. It has the characteristics of positive bending towards the laser beam when the temperature gradient plays a dominant role. It has the characteristics of short production cycle, low manufacturing cost and high quality of the plate after bending. This technology has been used in sheet metal forming since the 1980s. Summary of the invention

[0005] In order to solve the technical problems of complicated forming procedures, difficult forming, and many defects of traditional multi-scale special-shaped fins, the present invention combines the laser bending forming method, utilizes the acoustic field effect of ultrasonic surface waves and the thermal effect of laser, and proposes a special-shaped fin ultrasonic / laser composite multi-scale integrated forming process method and device. The present invention heats the fins by laser to form a micro-molten pool, and the ultrasonic surface wave generates a stable high-frequency sound field through a reversible fin fixture to transmit to the fins. After the laser scanning is completed, the liquid oscillating molten pool solidifies after being transmitted with the air to form a regular micro-texture; at the same time, after the texture is formed, the scanning process and scanning parameters are changed, and the scanning is alternately changed along the designed path on the front and back sides of the fixture to realize the special-shaped fin forming on the micro-textured surface.

[0006] The technical solution adopted by the present invention is:

[0007] A method for ultrasonic / laser composite multi-scale integrated forming of special-shaped fins, characterized in that it specifically comprises the following steps:

[0008] S1, pre-treating the fin to be formed to obtain the fin to be processed;

[0009] S2, clamping the fin to be processed, and transmitting the surface acoustic wave through the fixture equipped with the interdigital transducer during the laser scanning of the fin to prepare the functional surface micro-texture;

[0010] S3, laser bending the fins by using a reversible fixture;

[0011] S4. Take out the formed multi-scale special-shaped fins, perform wire cutting on the formed parts, remove the clamping area, and perform alcohol cleaning to remove the coated carbon black layer, dry, obtain the processed fins and perform subsequent assembly work.

[0012] Furthermore, in step S1, the specific process of pretreating the fins to be formed is as follows: pretreating the fins to be formed, and removing the residual stress of the fins themselves through a heat treatment process, sanding the treated fins to remove surface oxides, and coating the upper and lower surfaces of the fins with a carbon black layer, while presetting the clamping area and designing the scanning trajectory.

[0013] Furthermore, the specific process of step S2 is as follows: turn on the ultrasonic generator and the power amplifier, adjust the appropriate ultrasonic power, the ultrasonic generator generates a sound field, and amplifies the signal through the power amplifier and transmits it to the interdigital transducer on the loading fixture, so that the fixture surface where the interdigital transducer is located generates high-frequency vibration to form a stable ultrasonic surface wave, and the ultrasonic surface wave is transmitted to the fin through the fixture; synchronously set the laser texturing process parameters in the computer, and perform surface scanning. During the laser action, a micro-molten pool is generated in the fin scanning area due to the heat input of the laser, and the molten pool generates regular oscillations under the action of the acoustic surface. After the laser action ends, due to the sudden drop in temperature, the oscillating micro-molten pool contacts with the air for heat exchange, and solidifies to form a surface micro-texture with a stable regularity.

[0014] Furthermore, in step S3, the specific process of laser bending and forming by using a reversible fixture is as follows:

[0015] S31, designing the front and back scanning tracks by computer according to the special-shaped fin structure;

[0016] S32. Determine the process parameters, discretize different areas of the heating line, and adopt energy control strategies to achieve precise forming.

[0017] Furthermore, in step S1, the thickness of the selected fin material is a metal plate of sub-millimeter 304 stainless steel, and at the same time, the width of the metal plate should be less than the width of the clamp, and the length should be within the bendable range of the fin, and the aspect ratio of the processing area of ​​the metal plate should be maintained within 1 to 2 to ensure that the metal plate can be bent; the heat treatment temperature is 400 to 550°C, and the temperature is charged into the furnace for 2 to 4 hours, and then cooled with the furnace; the scanning trajectory is preset as a centrally symmetrical hyperbolic spline curve.

[0018] Furthermore, in step S2, in order to control the additional distortion of the fins, it is necessary to control the laser heat input, the laser power used is between 200 and 300 W, the laser diameter is between 125 and 200 μm, the scanning speed is between 1500 and 2000 mm / s, and the single scan is performed; the ultrasonic power ratio is between 30 and 40%, and the ultrasonic frequency is 31.84 kHz.

[0019] Furthermore, in step S3, the laser power used is between 150 and 250 W, the laser diameter is between 125 and 200 μm, the scanning speed is between 70 and 150 mm / s, the number of scans is between 10 and 100 times, and a segmented speed change process is performed during the scanning process to slow down the heat accumulation at the end of the scanning line and reduce the surface distortion of the formed thin plate.

[0020] Furthermore, during the scanning process, a single scanning line with a length of S is divided into eight equally spaced segments and the speeds are adjusted respectively.

[0021] Furthermore, the processed fins are cleaned, cut, and assembled with holes, and then post-processed by a machine and assembled.

[0022] A device for ultrasonic / laser composite multi-scale integrated forming of special-shaped fins, characterized in that it comprises a loading fixture, a galvanometer laser and an ultrasonic device, wherein the galvanometer laser transmits laser light through a galvanometer lens; the ultrasonic device comprises an ultrasonic generator and a power amplifier, the loading fixture comprises a fixture for clamping the fin to be formed, and the fixture is automatically flipped through a flipping mechanism; an interdigital transducer is arranged on one of the end faces of the fixture; the ultrasonic generator is connected to the interdigital transducer through a power amplifier; the laser mechanism is located above the fin to be formed, and the surface of the fin to be formed is always parallel to the worktable surface and is located at the focus of the galvanometer laser.

[0023] Furthermore, the flipping mechanism includes a motor, a transmission belt and a controller. The transmission belt is sleeved between the driving end of the motor and the fixed end of the loading fixture for transmitting the rotational power of the motor to the loading fixture. The controller is connected to the motor through an electrical signal for controlling the start and stop of the motor and adjusting the rotation speed of the loading fixture. The loading fixture and the motor are fixedly mounted on the work surface.

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

[0025] 1. The process of the present invention is simple, which is different from the traditional two-step forming method. It can realize the integrated forming of multi-scale special-shaped fins, and only requires a single clamping, which improves the production efficiency and can achieve certain economic and social benefits.

[0026] 2. The surface texture after forming of the present invention has high performance. The synchronous coupling of surface acoustic wave and laser can realize the wavy melting morphology. While increasing the contact area of ​​subsequent catalysts or other coating materials, it can also improve the heat exchange efficiency in the reaction process, thereby having better application performance.

[0027] 3. The forming of the special-shaped parts of the present invention is more accurate. When the laser bending forming technology is adopted, the consistency of the scanning position accuracy before and after the flipping can be ensured by quantitative design of the flipping fixture and the scanning line process parameters, and the degree of surface distortion during the scanning process can be reduced, thereby further improving the forming accuracy of the special-shaped parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the overall concept diagram of ultrasonic / laser composite multi-scale integrated forming of special-shaped fins of the present invention;

[0029] Figure 2a This is a schematic diagram of the ultrasonic / laser composite multi-scale integrated forming device for special-shaped fins of the present invention. Figure 1 ;

[0030] Figure 2b Schematic diagram 2 of the ultrasonic / laser composite multi-scale integrated forming device for special-shaped fins of the present invention;

[0031] Figure 3 This is a schematic diagram of scanning path planning for special-shaped parts of the present invention;

[0032] Figure 4 It is a schematic diagram of eight-segment scanning speed control of the present invention;

[0033] Figure 5 This is a schematic diagram of the laser forward scanning bending of the special-shaped fin of the present invention;

[0034] Figure 6 It is a schematic diagram of laser reverse scanning bending of the special-shaped fin of the present invention. DETAILED DESCRIPTION

[0035] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0037] The present invention will be described in detail below in conjunction with exemplary embodiments with reference to the accompanying drawings.

[0038] Example 1

[0039] In this embodiment, the fin 1 to be processed is a 304 stainless steel fin with a size of 65×30×0.4 mm (length×width×thickness).

[0040] refer to Figures 1 to 6 The present invention provides a method for ultrasonic / laser composite multi-scale integrated forming of a special-shaped fin, comprising the following steps:

[0041] S1. Clean and dry the fins to be formed, heat treat them at 450℃, put them into a warm furnace, keep them warm for 3 hours, cool them down with the furnace, and remove the residual stress of the fins. Grind the treated fins with 400-grit sandpaper to remove the surface oxide layer, and coat the upper and lower surfaces of the fins with a carbon black layer. Reserve a 10mm clamping width on the length, and design the following on the computer: Figure 3 The scanning trajectory shown, where the solid line and the dotted line are the trajectories on both sides of the fin respectively;

[0042] S2. Clamp the fin after path planning to the fixture, use a level to ensure that the fin surface is level with the workbench, and the fin processing surface is at the focus of the galvanometer laser. Turn on the ultrasonic generator and power amplifier, and adjust the ultrasonic power ratio to 30%; synchronously set the laser texturing process parameters and the scanning area to be surface texturing in the computer (for example, set the laser power to 200W, the scanning speed to 1500mm / s, and the spot diameter to 0.125mm). When the fin surface produces a stable frequency high-frequency vibration, perform a surface scan, and scan once until the scan is completed. The molten pool solidifies to form a surface micro-texture with a stable pattern;

[0043] S3. On the fin after surface texture, the computer draws the pre-planned Figure 3 The scanning path shown is scanned in sequence from right to left. To suppress the surface distortion during the scanning process, the scanning line with a single length of S is divided into eight equidistant segments and the speed is adjusted respectively. The speed setting is as follows: Figure 4 The laser parameters are adjusted to 250W laser power, 0.125mm spot diameter, 15 scans, and the scanning process is as follows: Figure 5 When reverse forming, rotate the fixture 180° in the fixed direction and continue scanning along the planned path, as shown in Figure 6 Before and after the fixture is turned over, ensure that the fin surface is always parallel to the workbench and at the focal point.

[0044] S4. Take out the formed multi-scale special-shaped fins, perform wire cutting on the formed parts, remove the clamping area, clean them with alcohol, remove the coated carbon black layer, dry them, and carry out subsequent assembly work.

[0045] In summary, according to Example 1, the ultrasonic / laser composite multi-scale integrated forming can be performed on the centrally symmetrical hyperbolic spline curve-shaped special-shaped fin structure.

[0046] Example 2

[0047] Reference Figure 1 As shown in Figure 2, a device for ultrasonic / laser composite multi-scale integrated forming of special-shaped fins of the present invention comprises a loading fixture 2, a galvanometer laser 4 and an ultrasonic device, wherein the galvanometer laser transmits laser light through a galvanometer lens 401; the ultrasonic device comprises an ultrasonic generator 201 and a power amplifier 202, the loading fixture 2 comprises a fixture for clamping the fin 1 to be formed, and the fixture is automatically flipped through a flipping mechanism; an interdigital transducer 203 is arranged on one of the end faces of the fixture; the ultrasonic generator 201 is connected to the interdigital transducer 203 through a power amplifier 202; the laser mechanism 4 is located above the fin 1 to be formed, and the surface of the fin 1 to be formed is always parallel to the worktable surface and is located at the focus of the galvanometer laser 4.

[0048] Wherein, the fixture is a piezoelectric substrate plate, and the material is piezoelectric crystal or piezoelectric ceramic.

[0049] The device 2 can achieve 360° free flipping, the interdigital transducer 203 generates high-frequency vibration through the ultrasonic generator 201 and the power amplifier 202, and transmits it to the fin 1 through the clamping device 2, forming a stable surface wave 5 on the fin, and the micro-molten pool formed by the laser 4 oscillates 301 under the action of the surface wave 5, and exchanges heat with the air after the laser is scanned, and solidifies to form a texture 3.

[0050] The flipping mechanism includes a motor 204, a transmission belt 205 and a controller 206. The transmission belt 205 is sleeved between the driving end of the motor 204 and the fixed end of the loading fixture 2. The controller 206 is connected to the motor 204 signal for start / stop control and speed adjustment of the loading fixture 2. The loading fixture 2 and the motor 204 are fixed to the work surface.

[0051] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0052] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0053] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0056] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for ultrasonic / laser composite multi-scale integrated forming of special-shaped fins, characterized in that: The specific steps include: S1, pre-treating the fin to be formed to obtain the fin to be processed; S2, clamping the fin to be processed, and transmitting the surface acoustic wave through the fixture equipped with the interdigital transducer during the laser scanning of the fin to prepare the functional surface micro-texture; S3, laser bending the fins by using a reversible fixture; S4, taking out the formed multi-scale special-shaped fins, performing wire cutting on the formed parts, removing the clamping area, and performing alcohol cleaning to remove the coated carbon black layer, drying, obtaining the processed fins (7) and performing subsequent assembly work.

2. The method for ultrasonic / laser composite multi-scale integrated forming of special-shaped fins according to claim 1, characterized in that: In step S1, the specific process of pre-treating the fins to be formed is as follows: pre-treating the fins to be formed, and removing the residual stress of the fins themselves through a heat treatment process, sanding the treated fins to remove surface oxides, and coating the upper and lower surfaces of the fins with a carbon black layer, while pre-setting the clamping area and designing the scanning trajectory.

3. The method for ultrasonic / laser composite multi-scale integrated forming of special-shaped fins according to claim 1, characterized in that: The specific process of step S2 is as follows: turn on the ultrasonic generator and the power amplifier, adjust the appropriate ultrasonic power, the ultrasonic generator generates a sound field, and amplifies the signal through the power amplifier and transmits it to the interdigital transducer on the loading fixture, so that the fixture surface where the interdigital transducer is located generates high-frequency vibration to form a stable ultrasonic surface wave, and the ultrasonic surface wave is transmitted to the fin through the fixture; synchronously set the laser texturing process parameters in the computer, and perform surface scanning. During the laser action, a micro-molten pool is generated in the fin scanning area due to the heat input of the laser, and the molten pool generates regular oscillations under the action of the acoustic surface. After the laser action ends, due to the sudden drop in temperature, the oscillating micro-molten pool contacts with the air for heat exchange, and solidifies to form a surface micro-texture with a stable regularity.

4. The method for ultrasonic / laser composite multi-scale integrated forming of special-shaped fins according to claim 1, characterized in that: In step S3, the specific process of laser bending and forming by using a reversible fixture is as follows: S31, designing the front and back scanning tracks by computer according to the special-shaped fin structure; S32. Determine the process parameters, discretize different areas of the heating line, and adopt energy control strategies to achieve precise forming.

5. The ultrasonic / laser composite multi-scale integrated forming method of a special-shaped fin according to claim 1, characterized in that: In the step S1, the thickness of the selected fin material is a metal plate of sub-millimeter 304 stainless steel, and at the same time, the width of the metal plate should be less than the width of the fixture, and the length should be within the bendable range of the fin. The aspect ratio of the processing area of ​​the metal plate should be maintained within 1 to 2 to ensure that the metal plate can be bent; the heat treatment temperature is 400 to 550°C, and the temperature is charged into the furnace for 2 to 4 hours, and then cooled with the furnace; the scanning trajectory is preset as a centrally symmetrical hyperbolic spline curve.

6. The ultrasonic / laser composite multi-scale integrated forming method of a special-shaped fin according to claim 1, characterized in that: In step S2, in order to control the additional distortion of the fins, the laser heat input needs to be controlled, the laser power used is between 200 and 300 W, the laser diameter is between 125 and 200 μm, the scanning speed is between 1500 and 2000 mm / s, and the single scan is performed; the ultrasonic power ratio is between 30 and 40%, and the ultrasonic frequency is 31.84 kHz.

7. The method for ultrasonic / laser composite multi-scale integrated forming of special-shaped fins according to claim 1, characterized in that: In step S3, the laser power used is between 150 and 250 W, the laser diameter is between 125 and 200 μm, the scanning speed is between 70 and 150 mm / s, the number of scans is between 10 and 100 times, and a segmented speed change process is performed during the scanning process to slow down the heat accumulation at the end of the scanning line and reduce the surface distortion of the formed thin plate.

8. The method for ultrasonic / laser composite multi-scale integrated forming of special-shaped fins according to claim 7, characterized in that: During the scanning process, a single scanning line with a length of S is divided into eight equidistant segments and the speed is adjusted respectively.

9. An ultrasonic / laser composite multi-scale integrated forming device for special-shaped fins, characterized in that: The invention comprises a loading fixture (2), a galvanometer laser (4) and an ultrasonic device, wherein the galvanometer laser transmits laser light through a galvanometer lens (401); the ultrasonic device comprises an ultrasonic generator (201) and a power amplifier (202); the loading fixture (2) comprises a fixture for clamping a fin (1) to be formed, and the fixture is automatically flipped through a flipping mechanism; an interdigital transducer (203) is arranged on one end surface of the fixture; the ultrasonic generator (201) is connected to the interdigital transducer (203) through a power amplifier (202); the laser mechanism (4) is located above the fin (1) to be formed, and the surface of the fin (1) to be formed is always parallel to the worktable and located at the focus of the galvanometer laser (4).

10. The ultrasonic / laser composite multi-scale integrated forming device for special-shaped fins according to claim 9, characterized in that: The flipping mechanism comprises a motor (204), a transmission belt (205) and a controller (206); the transmission belt (205) is sleeved between the driving end of the motor (204) and the fixed end of the loading fixture (2) and is used to transmit the rotational power of the motor (204) to the loading fixture (2); the controller (206) is connected to the motor (204) through an electrical signal and is used to control the start and stop of the motor (204) and adjust the rotation speed of the loading fixture (2); the loading fixture (2) and the motor (204) are fixedly installed on a work surface.

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