Preparation method of sintered heat pipe

Abstract

The invention relates to a preparation method of a sintered heat pipe, which comprises the following steps: inserting an outer diameter-adjustable core rod into a heat pipe shell, increasing the outer diameter of the outer diameter-adjustable core rod, filling a liquid absorption core raw material between the outer diameter-adjustable core rod and the heat pipe shell, setting the liquid absorption core raw material, reducing the outer diameter of the outer diameter-adjustable core rod, taking out the outer diameter-adjustable core rod, and sintering the outer diameter-adjustable core rod to obtain the sintered heat pipe. And then the heat pipe shell loaded with the shaped wick raw material is sintered, and a sintered heat pipe is obtained. According to the preparation method of the sintered heat pipe, the core rod with the adjustable outer diameter is used, the core rod can be taken out only by reducing the outer diameter of the core rod in advance during demolding, the demolding process is rapid and reliable, a demolding agent does not need to be coated, the production efficiency is improved, and introduction of impurity elements does not exist.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sintering, in particular to a preparation method of a sintered heat pipe. BACKGROUND

[0002] Heat pipes are widely used in the fields of power electronics, aerospace, etc., and are responsible for transmitting heat from the heat source to the cold end for release, so as to avoid damage to the core area due to heat accumulation. Sintered heat pipes are widely used in 80% of electronic chip heat dissipation scenarios due to the advantages of the sintered wick, such as capillary capacity and strong anti-gravity.

[0003] Currently, a core rod is often used as a mold in the preparation process of the sintered heat pipe. After the core rod is inserted into the heat pipe shell, the wick raw material is filled, and after shaping, sintering is performed to obtain the sintered heat pipe. Currently, a stainless steel core rod with a fixed outer diameter is usually used. If demolding is performed before sintering, friction will occur between the core rod and the shaped raw material during demolding, which will damage the shaped structure. If demolding is performed after sintering, the labor intensity of the core rod pulling-out process is high, and there is a risk of damage to the wick or even the whole wick falling off. Therefore, a release agent needs to be coated on the surface of the stainless steel core rod in actual use to greatly reduce the friction between the core rod and the shaped raw material during demolding. However, the introduction of the coating process of the release agent will reduce the production efficiency, and the residue of the release agent in the heat pipe raw material after coating will introduce other elements to deteriorate the performance of the heat pipe. In addition, in the case of copper water heat pipes, the composition of the release agent is complex, and there is a risk of chemical or electrochemical reaction between the release agent and the pipe shell or the wick, which will further cause the heat transfer performance of the heat pipe to decrease or even fail. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a preparation method of a sintered heat pipe. The outer diameter of the core rod can be adjusted, and the core rod can be taken out only by reducing the outer diameter of the core rod during demolding. The demolding process is rapid and reliable, and the release agent does not need to be coated, which improves the production efficiency and eliminates the introduction of impurity elements.

[0005] A preparation method of a sintered heat pipe includes the following steps: inserting an outer diameter adjustable core rod into a heat pipe shell, increasing the outer diameter of the outer diameter adjustable core rod, filling a wick raw material between the outer diameter adjustable core rod and the heat pipe shell, reducing the outer diameter of the outer diameter adjustable core rod and taking out the outer diameter adjustable core rod after the wick raw material is shaped, and then performing sintering treatment on the heat pipe shell loaded with the shaped wick raw material to obtain a sintered heat pipe.

[0006] The preparation method of the sintered heat pipe provided by the present application uses an outer diameter adjustable core rod. The core rod can be taken out only by reducing the outer diameter of the core rod during demolding. The demolding process is rapid and reliable, and the release agent does not need to be coated, which improves the production efficiency and eliminates the introduction of impurity elements.

[0007] Further, the method further comprises the steps of: inserting the outer diameter adjustable mandrel into the heat pipe shell, increasing the outer diameter of the outer diameter adjustable mandrel to less than 120% of the original outer diameter, filling the wick raw material between the outer diameter adjustable mandrel and the heat pipe shell, and then increasing the outer diameter of the outer diameter adjustable mandrel to 120% to 150% of the original outer diameter.

[0008] Further, the method further comprises the steps of: inserting the outer diameter adjustable mandrel into the heat pipe shell, increasing the outer diameter of the outer diameter adjustable mandrel to less than 120% of the original outer diameter, filling the wick raw material between the outer diameter adjustable mandrel and the heat pipe shell, and then increasing the outer diameter of the outer diameter adjustable mandrel to 120% to 150% of the original outer diameter.

[0009] Further, the outer diameter adjustable mandrel is provided with a pressure boosting groove, and an opening of the pressure boosting groove is located outside the heat pipe shell, and the pressure boosting groove extends in the same direction as the outer diameter adjustable mandrel. By inputting pressure, such as gas pressure or hydraulic pressure, into the pressure boosting groove and adjusting the pressure, the size of the outer diameter of the outer diameter adjustable mandrel can be adjusted.

[0010] Further, the method further comprises the steps of: inserting the outer diameter adjustable mandrel into the heat pipe shell, increasing the outer diameter of the outer diameter adjustable mandrel to less than 120% of the original outer diameter, filling the wick raw material between the outer diameter adjustable mandrel and the heat pipe shell, and then increasing the outer diameter of the outer diameter adjustable mandrel to 120% to 150% of the original outer diameter.

[0011] Further, the method further comprises the steps of: inserting the outer diameter adjustable mandrel into the heat pipe shell, increasing the outer diameter of the outer diameter adjustable mandrel to less than 120% of the original outer diameter, filling the wick raw material between the outer diameter adjustable mandrel and the heat pipe shell, and then increasing the outer diameter of the outer diameter adjustable mandrel to 120% to 150% of the original outer diameter.

[0012] Further, the outer diameter adjustable mandrel comprises a mandrel bottom and a mandrel wall, the mandrel bottom is in the shape of an inverted cone, one end of the mandrel wall is arranged around the outer periphery of the top surface of the inverted cone-shaped mandrel bottom, the mandrel wall and the mandrel bottom enclose the pressure boosting groove, the heat pipe shell comprises a shell bottom and a shell wall, the shell bottom is in the shape of an inverted cone, the top surface of the shell bottom is further provided with an inverted cone-shaped cavity, and one end of the shell wall is arranged around the outer periphery of the top surface of the shell bottom. When the outer diameter adjustable mandrel is inserted into the heat pipe shell, the bottom end of the mandrel bottom abuts against the bottom end of the cone-shaped cavity of the shell bottom.

[0013] Further, the outer diameter adjustable mandrel is made of a high polymer material, and the high polymer material comprises rubber, silicone, nylon, and polyethylene. The material for preparing the heat pipe shell comprises red copper, aluminum alloy, stainless steel, aluminum oxide, and aluminum nitride.

[0014] Further, the method further comprises the steps of: filling the wick raw material between the outer diameter adjustable mandrel and the heat pipe shell, and then vibrating the wick raw material.

[0015] Furthermore, the sintering process includes the following steps: placing the heat pipe shell containing the shaped liquid absorber core material into a reducing atmosphere for sintering; injecting an appropriate amount of liquid working fluid after sintering; and sequentially performing a first freezing removal, a second degassing, and a welding head treatment.

[0016] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0017] Fig. 1 This is a schematic diagram of the structure of the adjustable outer diameter mandrel according to an embodiment of the present invention; Fig. 2 This is a schematic diagram of the assembly structure of the adjustable outer diameter mandrel and the heat pipe shell according to an embodiment of the present invention; The components include an adjustable outer diameter core rod 1, a rod bottom 11, a rod wall 12, a pressure relief port 121, a pressure boosting groove 13, a positioning column 2, a heat pipe outer shell 3, a shell bottom 31, and a shell wall 32. Detailed Implementation

[0018] It should be understood that the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0019] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0020] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0021] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0022] It should be understood that the embodiments of this application are not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from their scope. The scope of the embodiments of this application is limited only by the appended claims.

[0023] To facilitate the explanation of the preparation method of the sintered heat pipe of the present invention, as a specific embodiment, please refer to the structure of the adjustable outer diameter mandrel 1, the three positioning posts 2, and the heat pipe shell 3. Figs. 1-2 The adjustable outer diameter core rod 1 is inserted into the heat pipe outer shell 3. The specific structure is described below: The adjustable outer diameter mandrel 1 includes a bottom 11 and a wall 12. The bottom 11 is inverted conical. One end of the wall 12 is arranged around the outer periphery of the top surface of the inverted conical bottom 11. The wall 12 and the bottom 11 form a pressure-boosting groove 13, such that the direction of the pressure-boosting groove 13 is the same as the direction of the adjustable outer diameter mandrel 1. The opening of the pressure-boosting groove 13 is located outside the heat pipe shell 3, and the opening of the pressure-boosting groove 13 is used as the pressure-boosting port. The wall 12 is also provided with a pressure-relief port 121, which is located outside the heat pipe shell 3. The inner diameter of the pressure-boosting port is larger than the inner diameter of the pressure-relief port 121. The positioning post 2 is located between the heat pipe shell 3 and the adjustable outer diameter mandrel 1. The positioning post 2 is fixed on the outer wall of the adjustable outer diameter mandrel 1. The positioning posts 2 are evenly distributed around the adjustable outer diameter mandrel 1, so that the interval angle between adjacent positioning posts 2 is 120°. Through the joint action of the evenly distributed positioning posts 2, it is beneficial to ensure the coaxial positioning of the adjustable outer diameter mandrel 1 and the heat pipe shell 3. The adjustable outer diameter mandrel 1 and the positioning post 2 of the present invention are both made of polymer materials. As a specific embodiment, the polymer materials include rubber, silicone, nylon, and polyethylene. The heat pipe housing 3 includes a bottom 31 and a wall 32. The bottom 31 is inverted conical, and the top surface of the bottom 31 is also provided with an inverted conical cavity. One end of the wall 32 is arranged around the outer periphery of the top surface of the bottom 31. When the adjustable outer diameter mandrel 1 is inserted into the heat pipe housing 3, the bottom end of the mandrel 11 abuts against the bottom end of the conical cavity of the bottom 31. As a specific embodiment, the materials used to prepare the heat pipe housing 3 of the present invention include copper, aluminum alloy, stainless steel, alumina, and aluminum nitride.

[0024] As a specific implementation method, the preparation method of the adjustable outer diameter mandrel 1 includes the following steps: axially extending and radially blow molding of nylon material to form an internally hollow mandrel 1 with an inverted conical solid bottom and pressure boosting port and pressure relief port 121 on the top.

[0025] As a specific implementation method, the preparation method of heat pipe shell 3 includes the following steps: cutting copper tubes of appropriate length, preparing groove structure inside the copper tubes by spiral drawing, forming a certain taper at the bottom end of the copper tubes after shrinking to form the shell bottom 31, and the remaining part as the shell wall 32 to form heat pipe shell 3; straightening the shell wall 32, and washing the heat pipe shell 3 as a whole for later use.

[0026] The liquid-absorbing core material of the present invention is metal, non-metal powder or short fiber.

[0027] The embodiments of the present invention are described based on the structures exemplified above. The preparation methods of the sintered heat pipes in the embodiments of the present invention all adopt the method of adjusting the outer diameter by adjusting the gas pressure.

[0028] Example 1 This embodiment provides a method for preparing a sintered heat pipe, including the following steps: With the heat pipe housing 3 vertical, insert the adjustable outer diameter mandrel 1 into the heat pipe housing 3, so that the bottom end of the adjustable outer diameter mandrel 11 is pressed against the bottom end of the conical cavity of the housing bottom 31. Then, block the pressure relief port 121, start the air pump and adjust the air pressure regulating valve, and inject air into the pressure boosting tank 13 through the pressure boosting port to boost the pressure. Under the action of the air pressure inside the pressure boosting tank 13, the outer diameter of the adjustable outer diameter mandrel 1 increases, and the three positioning pins 2 press against the inner wall of the heat pipe housing 3, so that the central axis of the adjustable outer diameter mandrel 1 is collinear with the central axis of the heat pipe housing 3. When the outer diameter of the adjustable outer diameter mandrel 1 increases to 115% of the original outer diameter, close the air pressure regulating valve. Next, copper powder (i.e., the liquid absorber material) is filled between the heat pipe shell 3 and the adjustable outer diameter mandrel 1 and compacted by a vibration table. The air pressure regulating valve is opened and air is continued to be filled into the pressurization tank 13 to expand the outer diameter of the adjustable outer diameter mandrel 1 to 150% of the original outer diameter (the outer diameter of the pressurization tank 13 when it is not filled with air). The air pressure regulating valve is closed and left to stand for 2 minutes to allow the liquid absorber material to set. Then, the pressure relief port 121 is opened to slowly release the gas in the pressurization tank 13. After the pressurization tank 13 returns to normal pressure, the adjustable outer diameter mandrel 1 is taken out. The heat pipe shell 3, which contains the shaped liquid absorber core material, is placed in a reducing atmosphere for sintering. After sintering, an appropriate amount of liquid working fluid is injected, and the heat pipe is subjected to freezing first, degassing second, and welding head treatment in sequence to obtain the sintered heat pipe.

[0029] Example 2 This embodiment provides a method for preparing a sintered heat pipe, including the following steps: The copper wire mesh is cut to the dimensions of the heat pipe length and the circumference of the adjustable outer diameter mandrel, and the wire mesh is laser welded along the length to form a wire mesh tube. Insert the adjustable outer diameter mandrel 1 into the wire mesh tube. Then, with the heat pipe shell 3 vertical, insert the adjustable outer diameter mandrel 1 with the wire mesh tube into the heat pipe shell 3, so that the bottom end of the adjustable outer diameter mandrel 11 is pressed against the bottom end of the conical cavity of the bottom 31 of the heat pipe shell 3. Then, block the pressure relief port 121, start the air pump and adjust the air pressure regulating valve. Inject air into the pressure boosting tank 13 through the pressure boosting port to boost the pressure. Under the action of the air pressure inside the pressure boosting tank 13, the outer diameter of the adjustable outer diameter mandrel 1 increases. The three positioning pins 2 press against the inner wall of the heat pipe shell 3, so that the central axis of the adjustable outer diameter mandrel 1 is collinear with the central axis of the heat pipe shell 3, and the wire mesh tube is in close contact with the surface of the mandrel. When the outer diameter of the adjustable outer diameter mandrel 1 increases to 105% of the original outer diameter, close the air pressure regulating valve. Next, copper powder (i.e., the liquid absorber material) is filled between the heat pipe shell 3 and the adjustable outer diameter mandrel 1 and compacted by a vibration table. The air pressure regulating valve is opened and air is continued to be filled into the pressurization tank 13 to expand the outer diameter of the adjustable outer diameter mandrel 1 to 120% of the original outer diameter (the outer diameter of the pressurization tank 13 when it is not filled with air). The air pressure regulating valve is closed and left to stand for 2 minutes to allow the liquid absorber material to set. Then, the pressure relief port 121 is opened to slowly release the gas in the pressurization tank 13. After the pressurization tank 13 returns to normal pressure, the adjustable outer diameter mandrel 1 is taken out. The heat pipe shell 3, containing the shaped liquid-absorbing core material and the wire mesh cylinder, is placed in a reducing atmosphere for sintering. After sintering, an appropriate amount of liquid working fluid is injected, and the heat pipe is subjected to freezing first, degassing second, and welding head treatment in sequence to obtain the sintered heat pipe.

[0030] Through extensive practical experience, the inventors discovered that existing methods for preparing sintered heat pipes suffer from the problem of the wire mesh tube not being able to be fixed on the mandrel due to the inability to change the outer diameter of the stainless steel mandrel during use. This makes the process of preparing the composite wicking core of the sintered wire mesh and powder quite difficult. However, the sintered heat pipe preparation method of this invention uses a mandrel with an adjustable outer diameter. The wire mesh tube can be initially fixed on the mandrel by adjusting the outer diameter of the mandrel, making the process of preparing the composite wicking core heat pipe of the wire mesh and powder sintering much simpler, further improving the heat transfer efficiency of the heat pipe, and providing a feasible solution for the application of composite wicking cores in the aerospace field.

[0031] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A method for preparing a sintered heat pipe, characterized in that, The process includes the following steps: inserting an adjustable mandrel into the heat pipe housing, increasing the outer diameter of the mandrel, filling the space between the adjustable mandrel and the heat pipe housing with absorbent core material, shaping the absorbent core material, reducing the outer diameter of the mandrel and removing the mandrel, and then sintering the heat pipe housing containing the shaped absorbent core material to obtain a sintered heat pipe.

2. The method for preparing a sintered heat pipe according to claim 1, characterized in that, It also includes the following steps: after filling the liquid absorbent core material between the adjustable outer diameter core rod and the heat pipe shell, the outer diameter of the adjustable outer diameter core rod is increased again.

3. The method for preparing a sintered heat pipe according to claim 2, characterized in that, Insert the adjustable mandrel into the heat pipe shell, increasing the outer diameter of the mandrel to less than 120% of the original outer diameter. After filling the space between the adjustable mandrel and the heat pipe shell with absorbent core material, increase the outer diameter of the mandrel to 120%~150% of the original outer diameter.

4. The method for preparing a sintered heat pipe according to claim 1, characterized in that, The adjustable outer diameter mandrel is provided with a pressure-boosting groove, the opening of which is located outside the heat pipe shell, and the direction in which the pressure-boosting groove extends is the same as the direction in which the adjustable outer diameter mandrel extends.

5. The method for preparing a sintered heat pipe according to claim 4, characterized in that, An adjustable mandrel is inserted into the heat pipe housing, and air is pumped into the pressurization tank to increase the outer diameter of the adjustable mandrel.

6. The method for preparing a sintered heat pipe according to claim 1, characterized in that, It also includes at least three positioning posts, which are located between the heat pipe shell and the adjustable outer diameter mandrel. The positioning posts are fixed on the outer wall of the adjustable outer diameter mandrel and are evenly distributed around the adjustable outer diameter mandrel.

7. The method for preparing a sintered heat pipe according to claim 1, characterized in that, The adjustable outer diameter mandrel includes a base and a wall. The base is inverted conical. One end of the wall is arranged around the outer periphery of the top surface of the inverted conical base. The wall and the base form a pressure-increasing groove. The heat pipe shell includes a shell base and a shell wall. The shell base is inverted conical. The top surface of the shell base is also provided with an inverted conical cavity. One end of the wall is arranged around the outer periphery of the top surface of the shell base. When the adjustable outer diameter mandrel is inserted into the heat pipe shell, the bottom end of the base abuts against the bottom end of the conical cavity of the shell base.

8. The method for preparing a sintered heat pipe according to claim 1, characterized in that, The adjustable outer diameter mandrel is made of polymer materials, including rubber, silicone, nylon, and polyethylene. The materials used to make the heat pipe shell include copper, aluminum alloy, stainless steel, alumina, and aluminum nitride.

9. The method for preparing a sintered heat pipe according to claim 1, characterized in that, It also includes the following steps: After filling the liquid absorbent core material between the adjustable outer diameter core rod and the heat pipe shell, the liquid absorbent core material is compacted by vibration.

10. The method for preparing a sintered heat pipe according to claim 1, characterized in that, The sintering process includes the following steps: placing the heat pipe shell containing the shaped liquid absorber core material into a reducing atmosphere for sintering; injecting an appropriate amount of liquid working fluid after sintering; and sequentially performing a first freezing process, a second degassing process, and a welding head treatment.

Images