A manufacturing process for a microchannel structure

Abstract

The present invention belongs to the technical field of metal forming and processing, and provides a manufacturing process for a microchannel structure, which includes machining a channel on the surface of a raw material plate to obtain a bottom plate; diffusion welding a cover plate on the surface of the bottom plate to cover the bottom plate to obtain a first preform; opening a groove on the surface of the first preform to obtain a second preform; using a mold to press and form the second preform to obtain a third preform; and filling and welding the groove on the surface of the third preform flat to obtain a microchannel structure with a curved surface. Before the pressing and forming, the present invention opens a groove on the surface of the first preform on the outer side in the bending direction of the designed microchannel structure. The groove can increase the extension degree of the rib between adjacent microchannels, reduce the extension degree of the side wall on the outer side of the microchannel or even eliminate the extension of the side wall on the outer side of the microchannel, avoid the thinning of the side wall on the outer side of the microchannel, so that the wall thickness of the microchannel is consistent, and ensure the structural integrity and strength performance of the microchannel.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal pressing forming, and particularly relates to a manufacturing process for a microchannel structure. Background Art

[0002] A microchannel structure is a precision structure with micro-sized channels. Due to its high surface area to volume ratio, efficient heat and mass transfer capabilities, and precise fluid control performance, it is widely used in heat exchangers, microreactors, etc.

[0003] During the process of using flat pressing to form a curved microchannel structure with a certain curvature from a microchannel structure, since the microchannels are hollow structures and the ribs between adjacent microchannels are solid structures, the arcwise extension degree of the outer sidewalls of the microchannels is much greater than that of the outer sides of the ribs. As a result, the outer sidewalls of the microchannels become thinner or even crack, seriously affecting the strength performance of the microchannels.

[0004] The prior art CN119259790A discloses a manufacturing process for a variable curvature thin-walled microchannel structure. This process compensates for the length of the bottom of the microchannel, that is, the outer sidewall of the microchannel, so that it has sufficient stretchable distance during the pressing forming process to avoid thinning or cracking of the bottom of the microchannel.

[0005] However, the effect of this process is still not ideal when manufacturing a microchannel structure with a larger curvature and continuous bending. Summary of the Invention

[0006] The present invention provides a manufacturing process for a microchannel structure, aiming to solve the above technical problems.

[0007] The present invention is implemented as follows. A manufacturing process for a microchannel structure includes the following steps:

[0008] Process grooves on the surface of a raw material plate according to the number of microchannels of the designed microchannel structure to obtain a bottom plate;

[0009] Diffusion-weld a cover plate on the surface of the bottom plate to cover the bottom plate, obtaining a first preform. The first preform has microchannels, and there are ribs between adjacent microchannels;

[0010] Open grooves on the surface of the first preform on the outer side in the bending direction of the designed microchannel structure to obtain a second preform. The length and position of the grooves correspond to the ribs one by one;

[0011] Press and form the second preform using a mold to obtain a third preform;

[0012] Fill and weld the grooves on the surface of the third preform to obtain a microchannel structure with a curved surface.

[0013] Further, after the groove is opened, the thickness of the rib of the second prefabricated plate is less than or equal to twice the wall thickness of the microchannel on the outer side in the bending direction of the designed microchannel structure.

[0014] Furthermore, the wall thicknesses of the inner and outer sides of the microchannel are equal.

[0015] Furthermore, after the groove is opened, the widths of the ribs between each microchannel and the groove are equal.

[0016] Furthermore, after the groove is opened, the width of the rib between the microchannel and the groove is equal to the wall thickness of the microchannel.

[0017] Furthermore, both the bottom and the opening of the groove have a rounded corner structure.

[0018] Furthermore, the radius of the rounded corner structure is 0.3 to 0.5 times the wall thickness of the microchannel.

[0019] Beneficial effects: The manufacturing process of the microchannel structure provided by the present invention disassembles the microchannel structure into a combined structure of a cover plate and a bottom plate. First, a channel is processed on the raw material plate to obtain the bottom plate, and then the cover plate and the bottom plate are combined and pressed into shape through a mold to obtain the microchannel structure. Before the pressing forming, a groove is opened on the surface of the first prefabricated plate on the outer side in the bending direction of the designed microchannel structure, that is, a groove is opened at the position of the rib. The length and position of the groove correspond to the rib one by one, which is equivalent to milling a notch or a release groove. The groove can weaken the rib, increase the extension degree of the rib between adjacent microchannels, reduce the extension degree of the outer side wall of the microchannel or even eliminate the extension of the outer side wall of the microchannel, avoid the thinning of the outer side wall of the microchannel, so that the wall thickness of the microchannel is consistent, and ensure the structural integrity and strength performance of the microchannel. For the curved surface microchannel structure with a larger curvature continuous bend, the present invention can greatly reduce the thinning or cracking of the outer side wall of the microchannel during the pressing forming process. Brief Description of the Drawings

[0020] Figure 1 is a schematic diagram of a curved surface microchannel structure.

[0021] Figure 2 is a schematic diagram of the manufacturing process of the microchannel structure provided by the embodiment of the present invention.

[0022] Figure 3 is an enlarged view of one end of the second prefabricated plate.

[0023] Figure 4 is a schematic diagram of the structure of the second prefabricated plate of another embodiment.

[0024] Figure 5 is a schematic diagram of the structure of the third prefabricated plate of another embodiment.

[0025] Figure 6 It is a schematic diagram of the microchannel structure of another embodiment.

[0026] Figure 7 It is a parameter diagram of the diffusion welding of the bottom plate and the cover plate in the embodiment of the present invention.

[0027] The reference numerals in the figure respectively represent: 1 - raw material plate, 2 - channel, 3 - bottom plate, 4 - cover plate, 5 - first prefabricated plate, 6 - microchannel, 7 - rib, 8 - groove, 9 - second prefabricated plate, 10 - mold, 11 - third prefabricated plate, 12 - microchannel structure, a - wall thickness of the microchannel, b - thickness of the rib of the remaining part, c - width of the rib between the microchannel and the groove. Specific Embodiments

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] As Figure 1 shown, the curved microchannel structure 12 with a large curvature has a plurality of microchannels 6. For the problems existing in the actual production of this structure, refer to Figure 2 , 3 , the embodiment of the present invention provides a manufacturing process for a microchannel structure, and this process includes the following steps:

[0030] S1: Process channels 2 on the surface of the raw material plate 1 according to the number of microchannels 6 of the designed microchannel structure 12 to obtain the bottom plate 3.

[0031] Before manufacturing the microchannel structure 12 with a curved surface, a model of the microchannel structure 12 with dimensional parameters is preset in advance. The size of the raw material plate 1 is determined according to the length, width and thickness of the model, and channels 2 with the same number as the microchannels are processed on the raw material plate 1.

[0032] S2: Diffusion-weld a cover plate on the surface of the bottom plate 3 to cover the bottom plate 4 to obtain the first prefabricated plate 5. The first prefabricated plate 5 has microchannels 6, and there are ribs 7 between adjacent microchannels 6.

[0033] The cover plate 4 covers each channel 2 on the bottom plate 2, and the protruding structures between the cover plate 4 and the adjacent channels 2 are combined into one body by diffusion welding to form the first prefabricated plate 5.

[0034] S3: Open grooves 8 on the surface of the first prefabricated plate 5 on the outer side in the bending direction of the designed microchannel structure 12 to obtain the second prefabricated plate 9. The length and position of the grooves 8 correspond to the ribs 7 one by one.

[0035] A groove 8 is opened according to the bending direction of the microchannel structure 12 to be manufactured, so as to weaken the rib 7, increase the degree of extension of the rib 7 during the pressing process, make the rib 7 more likely to extend during the pressing process, reduce the degree of extension of the outer side wall of the microchannel or even eliminate the extension of the outer side wall of the microchannel, make the deformation degree of the rib 7 and the outer side wall of the microchannel tend to be consistent, so that the wall thickness of the microchannel is uniform, and avoid the thinning and cracking of the outer side wall of the microchannel. The surface where the groove 8 is opened is selected on the outer side of the bending direction, that is, the extension surface of the microchannel structure 12.

[0036] The size of the groove 8 is such that after the groove 8 is opened, the thickness of the rib 7 of the second prefabricated plate 9 is less than or equal to twice the wall thickness of the microchannel 6 on the outer side of the bending direction of the designed microchannel structure 12. As Figure 3 shown, if the wall thickness of the microchannel 6 is a and the thickness of the remaining rib 7 after the groove 8 is opened is b, then b ≤ 2a.

[0037] In addition, in the embodiment of the present invention, as Figure 3 shown, the wall thicknesses of the inner and outer sides of the microchannel 6 are equal, both being a.

[0038] In order to ensure uniform extension of each part of the second prefabricated plate 9 during the pressing process, after the groove 8 is opened, the widths of the ribs 7 between each microchannel 6 and the groove 8 are made equal.

[0039] At the same time, after the groove 8 is opened, the width of the rib 7 between the microchannel 6 and the groove 8 is equal to the wall thickness a of the microchannel 6. As Figure 3 shown, if the width of the rib 7 between the microchannel 6 and the groove 8 is c, then c = a.

[0040] In order to avoid stress concentration during the pressing process, as Figure 3 shown, both the bottom and the opening of the groove 8 are provided with fillet structures. The fillet radius of the fillet structure is 0.3 - 0.5 times the wall thickness of the microchannel, that is, 0.3a - 0.5a.

[0041] S4: The second prefabricated plate 9 is pressed into shape by using the mold 10 to obtain the third prefabricated plate 11.

[0042] S5: The groove 8 on the surface of the third prefabricated plate 11 is filled and welded flat to obtain the microchannel structure 12 with a curved surface.

[0043] After pressing into shape, the groove 8 on the surface of the third prefabricated plate 11 is filled and leveled by laser welding or argon arc welding to obtain the microchannel structure 12 with a flat surface and a curved surface.

[0044] The following is described in detail through specific embodiments.

[0045] Embodiment 1

[0046] An embodiment of the present invention provides a manufacturing process for a microchannel structure, including the following steps:

[0047] Part and tooling preparation: Prepare the raw material plate and the cover plate. The raw material plate and the cover plate are made of 304 stainless steel, with a length and width of 90 mm each. The thickness of the cover plate is 1 mm, the surface roughness of the diffusion welding surface of the cover plate is better than 0.8 μm, and the flatness is better than 0.01 mm.

[0048] The thickness of the raw material plate is 3 mm. 13 grooves with a width of 2 mm and a depth of 2 mm are processed equidistantly on the raw material plate. The spacing between adjacent grooves (the width of the rib) is 5 mm. The surface roughness of the diffusion welding surface of the raw material plate is better than 0.8 μm, and the flatness is better than 0.01 mm, obtaining the bottom plate.

[0049] The bottom plate and the cover plate are first degreased chemically, cleaned thoroughly with tap water, electrochemically polished on the surface, cleaned with an alkaline metal cleaning agent, cleaned thoroughly with tap water, and then dried.

[0050] The bottom plate and the cover plate are then nickel-plated on the surface, rinsed thoroughly with tap water, cleaned and rinsed multiple times with deionized water, and dried for standby.

[0051] Before diffusion welding the bottom plate and the cover plate, apply a solder mask on the surface of each welding tooling and dry for standby.

[0052] Assemble the bottom plate and the cover plate so that the cover plate coincides with the bottom plate. Use argon arc welding to spot-weld and fix at the surrounding joints of the cover plate and the bottom plate, and then transfer the whole to the diffusion welding furnace and perform vacuum diffusion welding according to the Figure 7 shown diffusion welding parameters to obtain the first prefabricated plate. The wall thickness of the microchannels in the first prefabricated plate is 1 mm.

[0053] After the first prefabricated plate is cooled, it is taken out of the furnace. Grooves with a depth of 2 mm and a width of 3 mm are processed at the positions corresponding to the ribs on the bottom surface of the first prefabricated plate. Fillet structures with a fillet radius of 0.5 mm are processed at the bottom and the opening of the grooves, obtaining the second prefabricated plate.

[0054] Heat the second prefabricated plate in a heating furnace with a protective gas to 900 °C, hold for 1 h, and then put it into a C-shaped pressing die with a bending angle of 136 degrees for pressing to obtain the third prefabricated plate.

[0055] Fill the grooves on the bottom surface of the third prefabricated plate by laser welding to obtain a microchannel structure with a C-shaped curved surface, see Figure 2 .

[0056] Example 2

[0057] An embodiment of the present invention provides a manufacturing process for a microchannel structure, including the following steps:

[0058] Part and tooling preparation: Prepare the raw material plate and the cover plate. The raw material plate and the cover plate are made of 304 stainless steel, with a length and width of 90 mm. The thickness of the cover plate is 1 mm. The surface roughness of the diffusion welding of the cover plate is better than 0.8 μm, and the flatness is better than 0.01 mm.

[0059] The thickness of the raw material plate is 3 mm. 13 grooves with a width of 2 mm and a depth of 2 mm are equally spaced on the raw material plate. The spacing between adjacent grooves (the width of the rib) is 5 mm. The surface roughness of the diffusion welding of the raw material plate is better than 0.8 μm, and the flatness is better than 0.01 mm, obtaining the bottom plate.

[0060] The bottom plate and the cover plate are first degreased chemically, cleaned thoroughly with tap water, electrochemically polished on the surface, cleaned with an alkaline metal cleaning agent, cleaned thoroughly with tap water, and dried.

[0061] The bottom plate and the cover plate are then nickel-plated on the surface, rinsed thoroughly with tap water, cleaned with deionized water and rinsed multiple times, and dried for standby.

[0062] Before the diffusion welding of the bottom plate and the cover plate, apply a soldermask on the surface of each welding tooling and dry for standby.

[0063] Assemble the bottom plate and the cover plate so that the cover plate coincides with the bottom plate. Fix them by spot welding with argon arc welding at the surrounding joints of the cover plate and the bottom plate, and then transfer the whole to the diffusion welding furnace. According to Figure 7 the shown diffusion welding parameters, perform vacuum diffusion welding to obtain the first prefabricated plate. The wall thickness of the microchannel in the first prefabricated plate is 1 mm.

[0064] After the first prefabricated plate is cooled, it is taken out of the furnace. Grooves with a depth of 2.5 mm and a width of 3 mm are machined at the positions corresponding to the ribs on the bottom surface of the left half of the first prefabricated plate. Grooves with a depth of 2.5 mm and a width of 3 mm are machined at the positions corresponding to the ribs on the top surface of the right half of the first prefabricated plate. Fillet structures with a fillet radius of 0.5 mm are machined at the bottom and the opening of the grooves, obtaining the second prefabricated plate. See Figure 4

[0065] Heat the second prefabricated plate to 900 °C in a heating furnace with protective gas, hold for 1 h, and then put it into an S-shaped profiling die with both sides bent at an angle of 136 degrees for profiling, obtaining the third prefabricated plate. See Figure 5

[0066] Fill the grooves on the bottom surface of the left half and the top surface of the right half of the third prefabricated plate by argon arc welding, obtaining a microchannel structure with an S-shaped curved surface. See Figure 6

[0067] ​​​The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A manufacturing process for a microchannel structure, characterized in that, The steps include: Machining grooves on the surface of the raw material plate according to the number of microchannels of the designed microchannel structure to obtain a bottom plate; Diffusion-welding a cover plate on the surface of the bottom plate to cover the bottom plate to obtain a first prefabricated plate, the first prefabricated plate having microchannels, and ribs between adjacent microchannels; Opening grooves on the surface of the first prefabricated plate on the outer side of the bending direction of the designed microchannel structure to obtain a second prefabricated plate, the length and position of the grooves corresponding one by one to the ribs; Pressing and forming the second prefabricated plate by using a mold to obtain a third prefabricated plate; Filling and welding the grooves on the surface of the third prefabricated plate to obtain a microchannel structure with a curved surface.

2. The manufacturing process of the microchannel structure according to claim 1, characterized in that, After opening the grooves, the thickness of the ribs of the second prefabricated plate is less than or equal to twice the wall thickness of the microchannels on the outer side of the bending direction of the designed microchannel structure.

3. The manufacturing process of the microchannel structure according to claim 2, characterized in that, The wall thicknesses of the inner and outer sides of the microchannels are equal.

4. The manufacturing process of the microchannel structure according to claim 2, characterized in that, After opening the grooves, the widths of the ribs between each microchannel and the groove are equal.

5. The manufacturing process of the microchannel structure according to claim 4, characterized in that, After opening the grooves, the width of the rib between the microchannel and the groove is equal to the wall thickness of the microchannel.

6. The manufacturing process of the microchannel structure according to claim 2, characterized in that, Both the bottom and the opening of the groove have a rounded corner structure.

7. The manufacturing process of the microchannel structure according to claim 6, characterized in that, The radius of the rounded corner structure is 0.3 to 0.5 times the wall thickness of the microchannel.

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