A method for manufacturing a high-performance ultra-thin heat pipe wick

Abstract

The application discloses a kind of high-performance ultra-thin heat pipe wick manufacturing method, comprising: step one: pipe material pretreatment;Step two: insert support block, braid and core rod;Step three: fill metal powder with copper powder into heat pipe shell 1, and the filling height is flush with the upper surface of support block 5.Powder is evenly distributed by vibration.Step four: sintering and support block decomposition;Step five: pull out core rod, shrink tail, welding, reduction;Step six: liquid injection, degassing, welding;Step seven: flattening shaping.The wick structure sintering is good, and the thermal resistance is low: evaporation zone uses metal powder sintering block directly with shell inner wall sintering, and the adhesion strength is high, the contact thermal resistance is small, which is superior to the deficiency of metal wire mesh easy to fall off, and the adhesion is poor.Capillary backflow is efficient: flat braid provides low flow resistance quick liquid diffusion channel along the way in condensation zone and heat insulation zone, and the metal powder sintering block capillary network in evaporation zone seamlessly connects, and working medium backflow is smooth.

Description

Technical Field

[0001] This invention relates to the field of ultrathin heat pipe technology, and more specifically to a method for manufacturing a high-performance ultrathin heat pipe wick. Background Technology

[0002] There are two main schemes for the wick structure of existing ultrathin heat pipes. The first is a partial powder plus braided tape structure (powder plus wire structure), which uses a sintered metal powder layer in the evaporation zone and a braided tape in the condensation and insulation zones. This scheme has good sintered powder adhesion and low thermal resistance, but because the powder occupies a considerable amount of internal space in the evaporation zone, the vapor flow channel is narrow. High-speed vapor has high frictional resistance in the narrow channel, resulting in a significant flow pressure drop. Under high power conditions, this can easily disrupt the gas-liquid circulation balance and limit the heat transfer capacity of the heat pipe.

[0003] The second type is a metal wire mesh plus braided tape structure (mesh plus wire structure), which uses metal wire mesh instead of metal powder. This scheme has a relatively large internal vapor space, but the sintering adhesion between the metal wire mesh and the inner wall of the heat pipe shell is poor, the capillary force is insufficient, which leads to obstruction of liquid working fluid reflux, high overall thermal resistance, and low production yield.

[0004] Furthermore, in traditional flattening processes, the sintering thickness of metal powder is uneven, often resulting in excessively thick sintered blocks after flattening. This severely compresses the evaporation space, further increasing thermal resistance and leading to a significant decline in heat pipe performance. Therefore, how to increase the evaporation zone space and reduce steam flow resistance while ensuring good sintering adhesion and capillary force is a pressing technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for manufacturing a high-performance ultrathin heat pipe wick, so as to solve the problem that it is difficult to balance evaporation space and sintering fit in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for fabricating a high-performance ultrathin heat pipe wick.

[0008] The high-performance ultrathin heat pipe wick includes: a heat pipe shell, within which a composite wick and a support block are provided; the composite wick is composed of a flat braided strip and a sintered metal powder block; the flat braided strip extends along the length of the heat pipe shell, is located in the condensation section and the insulation section of the heat pipe shell, and is sintered and bonded to the inner wall of the heat pipe shell; the sintered metal powder block is located in the evaporation section and is sintered and bonded to the inner wall of the heat pipe shell;

[0009] The support block and the flat braided strip are attached to the surface of the single-sided mandrel. The support block is set in the evaporation section and is located inside the inner wall of the metal powder sintered block in this section, so as to form an evaporation space by thermal decomposition and removal after sintering and shaping.

[0010] The production method is as follows:

[0011] Step 1: Provide a circular hollow heat pipe shell, i.e., a metal tube, with one end open, and perform head reduction and cleaning.

[0012] Step 2: Insert the support block and the flat braided strip together into the heat pipe housing using a single-sided mandrel, wherein the support block is in contact with the single-sided mandrel, and the flat braided strip is located between the single-sided mandrel and the inner wall of the heat pipe housing;

[0013] Step 3: Fill the heat pipe housing with metal powder, the filling height of which is flush with the support block;

[0014] Step 4: Place the filled heat pipe shell into the fixture and place it in the sintering furnace for sintering, so that the metal powder is sintered and shaped, while the support block gradually decomposes during the sintering process.

[0015] Step 5: Pull the single-sided mandrel out of the heat pipe housing, and perform tail reduction, welding, and restoration processes;

[0016] Step Six: Perform liquid injection, first removal, second removal, and welding on the reduced heat pipe shell;

[0017] Step 7: Shape and flatten the welded heat pipe shell until it meets the design requirements for an ultra-thin heat pipe.

[0018] Furthermore, the flat braided tape is made of several metal wires and runs through the condensation section and the insulation section of the heat pipe shell; the flat braided tape uses the capillary channels formed by its braided structure to quickly adsorb the condensed liquid working fluid and transport it to the evaporation section along its length.

[0019] Furthermore, the sintered metal powder block has a ring structure and is sintered and attached to the circumferential inner wall of the heat pipe shell corresponding to the evaporation section. The inner side of the sintered metal powder block is in contact with the flat braided strip to form a composite liquid wick with a continuous structure and strong capillary force.

[0020] Furthermore, the support block is made of a material that can be completely thermally decomposed at high temperatures (such as engineering plastics or composites of polycarbonate, polyoxymethylene, etc.). During the high-temperature sintering and shaping process of the metal powder, it gradually decomposes into volatile gases, which are then completely removed during the reduction and degassing processes in the heat pipe manufacturing process, leaving no gas-solid two-phase impurities. The space originally occupied by the support block becomes an evaporation space after decomposition. The support block partially decomposes during the sintering process in step four and completely volatilizes during the subsequent reduction in step five and the first and second degassing processes in step six. In step two, after the support block is attached to the single-sided core rod, its relative position remains unchanged during the subsequent powder filling and vibration process.

[0021] Furthermore, the support block is attached to the inner wall of the metal powder sintering block, and its end abuts against the flat woven strip. Before sintering, the support block plays a dual role of occupying and positioning: on the one hand, it provides a template for the shape and position of the subsequent evaporation space, and on the other hand, it prevents the metal powder from sticking too thickly to the inner wall of the tube during the powder filling vibration process, so as to ensure that the powder filling is uniform.

[0022] The technical effects and advantages of this invention are as follows:

[0023] Large evaporation space and smooth steam flow: The support block is removed by thermal decomposition after sintering, forming a regular and spacious evaporation space in the evaporation zone. The cross-sectional area of ​​the steam flow channel is significantly larger than that of the traditional powder-added wire structure, which reduces the steam flow pressure drop and improves the heat transfer limit of the heat pipe under high power conditions.

[0024] Good sintering adhesion and low thermal resistance: The evaporation zone uses metal powder sintered blocks to be directly sintered and bonded to the inner wall of the shell, which has high bonding strength and low contact thermal resistance, and is superior to the shortcomings of metal wire mesh that is easy to fall off and has poor adhesion.

[0025] High efficiency of capillary reflux: The flat braided belt provides a fast liquid diffusion channel with low flow resistance in the condensation zone and the insulation zone, and seamlessly connects with the capillary network of metal powder sintered blocks in the evaporation zone, ensuring smooth recirculation of the working fluid.

[0026] Good manufacturing process compatibility: The support block is naturally decomposed and removed during the sintering process, without the need for additional mechanical removal steps, and is compatible with existing heat pipe sintering processes. Attached Figure Description

[0027] Figure 1 This is a planar schematic diagram of the ultrathin heat pipe liquid absorption core structure of the present invention;

[0028] Figure 2 for Figure 1 AA cross-sectional view (before sintering);

[0029] Figure 3 for Figure 2 Enlarged view within the dashed box;

[0030] Figure 4 This is a perspective view of the ultrathin heat pipe liquid absorption core structure of the present invention (the support block has been decomposed after sintering).

[0031] Figure 5 for Figure 4 Enlarged view of the area circled in the middle;

[0032] Figure 6 Schematic diagram of composite liquid absorption core;

[0033] Figure 7 A schematic diagram showing the location of the flat braided tape sintered inside the heat pipe housing;

[0034] Figure 8 This is a flowchart of the manufacturing method of the present invention;

[0035] Figure 9 This is a schematic diagram showing the support block and flat braided strip attached to the surface of a single-sided mandrel. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] A method for fabricating a high-performance ultrathin heat pipe wick includes:

[0039] Step 1: Pipe Pretreatment

[0040] A circular hollow copper tube is provided as the heat pipe housing 1, one end of which is tapered to form an opening, and ultrasonically cleaned to remove oil and oxides.

[0041] Step Two: Inserting the Support Block, Braided Tape, and Mandrel. Insert the support block 5 (made of a thermoplastic material) and the flat braided tape 3 together into the heat pipe housing 1 using the single-sided mandrel 7. Specifically, one side of the single-sided mandrel 7 has a groove or flat surface; the support block 5 fits against this side, and the flat braided tape 3 is placed on the groove or flat surface. This ensures that the support block 5 and the single-sided mandrel 7 will not shift relative to each other or detach during the subsequent powder filling vibration process.

[0042] Step 3: Fill with metal powder. Fill the heat pipe housing 1 with copper powder, making sure the filling height is flush with the upper surface of the support block 5. Use vibration to distribute the powder evenly.

[0043] Step 4: Sintering and Decomposition of Support Block. The filled heat pipe shell 1 is placed in a fixture and then placed in a sintering furnace for sintering. During this process, the copper powder is sintered and shaped to form a porous metal powder sintered block 2, while the support block 5 gradually decomposes into volatile gases at high temperature and is discharged through the pipe opening.

[0044] Step 5: After removing the mandrel, tail reduction, welding, and reduction sintering, remove the single-sided mandrel 7 from the heat pipe housing 1. Then perform tail reduction (to seal the other end), weld the end cap, and perform another reduction treatment (to further remove oxides).

[0045] Step Six: Liquid Injection, Degassing, and Welding. The reduced heat pipe shell 1 is injected with liquid (working fluid, such as pure water), degassed once (vacuum degassing), degassed again, and finally welded and sealed.

[0046] Step 7: Flattening and Shaping. The round tube after welding and sealing is flattened and shaped to achieve the design requirements for an ultra-thin heat pipe (e.g., 0.4mm~1.0mm). After flattening, since the support block 5 has been decomposed and left with a cavity, the metal powder will not be excessively compressed, and the evaporation zone channel will remain unobstructed.

[0047] Example 2

[0048] A method for manufacturing a high-performance ultrathin heat pipe wick, as shown in Figures 1 to 1, includes a heat pipe shell 1, within which a composite wick and a support block are provided; the composite wick is composed of a flat braided strip 3 and a sintered metal powder block 2; the flat braided strip 3 extends along the length of the heat pipe shell, and is located in the condensation section 13 and the insulation section 12 of the heat pipe shell, and is sintered and bonded to the inner wall of the heat pipe shell; the sintered metal powder block 2 is located in the evaporation section 11, and is sintered and bonded to the inner wall of the heat pipe shell;

[0049] The support block 5 is disposed in the evaporation section, located inside the inner wall of the metal powder sintered block in this section, so as to form the evaporation space 6 by thermal decomposition and removal after sintering and shaping. Figure 2 Support block 5 in the diagram is only shown in the diagram; it has actually been disassembled.

[0050] Furthermore, the flat braided tape is made of several metal wires and runs through the condensation section and the insulation section of the heat pipe shell; the flat braided tape uses the capillary channels formed by its braided structure to quickly adsorb the condensed liquid working fluid and transport it to the evaporation section along its length.

[0051] Furthermore, the sintered metal powder block 2 has a ring structure and is sintered and attached to the circumferential inner wall of the heat pipe shell corresponding to the evaporation section. The inner side of the sintered metal powder block is in contact with the flat braided belt to form a composite liquid wicking core with continuous structure and strong capillary force.

[0052] Furthermore, the support block is made of organic materials that can be completely thermally decomposed at sintering temperatures (such as polycarbonate, polyoxymethylene, and other engineering plastics or their composites). During the high-temperature sintering and shaping process of the metal powder, it gradually decomposes into volatile gases, which are then completely removed in the reduction and degassing processes of the heat pipe manufacturing process, leaving no gas-solid two-phase impurities. The space originally occupied by the support block becomes an evaporation space after decomposition.

[0053] Furthermore, the support block is attached to the inner wall of the metal powder sintering block, and its end abuts against the flat woven strip. Before sintering, the support block plays a dual role of occupying and positioning: on the one hand, it provides a template for the shape and position of the subsequent evaporation space, and on the other hand, it prevents the metal powder from sticking too thickly to the inner wall of the tube during the powder filling vibration process, so as to ensure that the powder filling is uniform.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a high-performance ultrathin heat pipe wick, characterized in that, Includes the following steps: Step 1: Provide a circular hollow heat pipe shell, i.e., a metal tube, with one end open, and perform head reduction and cleaning. Step 2: Insert the support block and the flat braided strip together into the heat pipe housing using a single-sided mandrel, wherein the support block is in contact with the single-sided mandrel, and the flat braided strip is located between the single-sided mandrel and the inner wall of the heat pipe housing; Step 3: Fill the heat pipe housing with metal powder, the filling height of which is flush with the support block; Step 4: Place the filled heat pipe shell into the fixture and place it in the sintering furnace for sintering, so that the metal powder is sintered and shaped, while the support block gradually decomposes during the sintering process. Step 5: Pull the single-sided mandrel out of the heat pipe housing, and perform tail reduction, welding, and restoration processes; Step Six: Perform liquid injection, first removal, second removal, and welding on the reduced heat pipe shell; Step 7: Shape and flatten the welded heat pipe shell until it meets the design requirements for an ultra-thin heat pipe.

2. The method for manufacturing a high-performance ultrathin heat pipe wick according to claim 1, characterized in that: The heat pipe housing is provided with a composite liquid wicking core and a support block; the composite liquid wicking core is composed of a flat braided strip and a sintered metal powder block; the flat braided strip extends along the length of the heat pipe housing, and is located in the condensation section and the insulation section of the heat pipe housing, and is sintered and attached to the inner wall of the heat pipe housing; the sintered metal powder block is located in the evaporation section, and is sintered and attached to the inner wall of the heat pipe housing; The support block and flat braided tape are attached to the surface of a single-sided mandrel so that they can be thermally decomposed and removed after sintering and shaping to form an evaporation space.

3. The method for manufacturing a high-performance ultrathin heat pipe wick according to claim 1, characterized in that: The flat braided tape is made of several metal wires and runs through the condensation section and the insulation section of the heat pipe shell. The flat braided tape uses the capillary channels formed by its braided structure to quickly adsorb the condensed liquid working fluid and transport it to the evaporation section along its length.

4. The method for manufacturing a high-performance ultrathin heat pipe wick according to claim 1, characterized in that: The sintered metal powder block has a ring structure and is sintered and attached to the circumferential inner wall of the heat pipe shell corresponding to the evaporation section. The inner side of the sintered metal powder block is in contact with the flat braided belt to form a composite liquid wick with a continuous structure and strong capillary force.

5. The method for manufacturing a high-performance ultrathin heat pipe wick according to claim 1, characterized in that: The support block is made of organic material that can be completely thermally decomposed at the sintering temperature. During the high-temperature sintering and shaping process of metal powder, it is gradually thermally decomposed into volatile gas, which is then completely removed in the degassing process of the heat pipe manufacturing process, leaving no gas-solid two-phase impurities. The space originally occupied by the support block becomes an evaporation space after decomposition.

6. The method for manufacturing a high-performance ultrathin heat pipe wick according to claim 1, characterized in that: The support block is attached to the inner wall of the metal powder sintering block, and its end abuts against the flat woven strip. Before sintering, the support block plays a dual role of occupying and positioning: on the one hand, it provides a template for the shape and position of the subsequent evaporation space, and on the other hand, it prevents the metal powder from sticking too thickly to the inner wall of the tube during the powder filling vibration process, so as to ensure that the powder filling is uniform.

7. The method for manufacturing a high-performance ultrathin heat pipe wick according to claim 1, characterized in that: The support block is made of a material that can be completely thermally decomposed at high temperatures.

8. The method for manufacturing a high-performance ultrathin heat pipe wick according to claim 1, characterized in that: The support block undergoes partial thermal decomposition during the sintering process in step four, and is completely volatilized during the subsequent reduction process in step five and the first and second division processes in step six.

9. The method for manufacturing a high-performance ultrathin heat pipe wick according to claim 1, characterized in that: In step two, after the support block is attached to the single-sided mandrel, its relative position remains unchanged during the subsequent powder filling and vibration process.

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