Flat heat pipe structure prepared based on selective laser melting (SLM) technology

Abstract

The invention particularly relates to a flat plate heat pipe structure prepared based on a selective laser melting (SLM) technology. The flat plate heat pipe structure is composed of a liquid absorption core, an upper plate, a lower plate, a side wall, a supporting column, a liquid injection opening and the like. The device is characterized in that the lower part of the upper plate is in contact with the support column or the side wall and the capillary core, and the contact area accounts for more than 80% of the projection area of the upper plate on a processing plane. When the axis of the supporting column is parallel to the machining plane, the portion, smaller than 30 degrees, of the lower tangent plane and the machining plane must make contact with the capillary core. The capillary core at the lower part of the upper plate or the supporting column is contacted with the supporting column or the side wall by adopting a conical surface or an inclined surface; and the included angle between the tangent plane of the conical surface or the inclined surface and the processing plane is not less than 30 degrees. The 3D printer has the beneficial effects that printing preparation can be conducted in the mode that the upper plate and the lower plate are parallel to the machining plane, and the printing efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to a flat heat pipe structure prepared by selective laser melting (SLM) technology, and is applicable to the design and preparation of flat heat pipe structures in thermal management systems. Background Art

[0002] As an effective thermal management device, flat heat pipes are widely used in fields such as electronic devices, lasers, solar thermal collection systems, and electric vehicles. Its main function is to evenly distribute heat to prevent local overheating and improve the overall heat dissipation efficiency of the system. The design of traditional flat heat pipes usually relies on simple planar structures, making it difficult to meet the increasing power density and heat dissipation requirements.

[0003] In recent years, with the reduction in volume and increase in power of electronic components, flat heat pipes face new challenges in structural design and material selection. Traditional manufacturing methods, such as milling and powder sintering, are difficult to effectively achieve the preparation of complex geometries, which significantly increases the manufacturing cost and cycle of flat heat pipes.

[0004] The emergence of selective laser melting (SLM) technology provides a new idea for the manufacture of flat heat pipes. SLM technology can build complex three-dimensional structures by layer-by-layer melting of metal powders, allowing the introduction of more efficient fluid channels and heat exchange areas in the design. This manufacturing method can not only improve the heat conduction performance, but also reduce material waste and improve production efficiency. By adjusting the energy density of laser scanning or designing the laser scanning path, a flat heat pipe with a composite structure of porous and dense structures can be prepared.

[0005] The current flat heat pipe structure is mainly designed based on the powder sintering method. When prepared by SLM technology, the flat heat pipe needs to be tilted at a certain angle for printing preparation to prevent serious deformation during the printing process, increasing the printing support and preparation cycle.

[0006] The present invention aims to provide a flat heat pipe structure suitable for preparation by selective laser melting (SLM) technology, which can be printed with the upper plate completely parallel to the processing platform, reducing the printing cycle and improving the printing efficiency. Summary of the Invention

[0007] The purpose of the present invention is to provide a flat heat pipe structure suitable for preparation by selective laser melting (SLM) technology to improve its preparation efficiency.

[0008] The flat heat pipe structure includes an upper plate, a lower plate, side walls, support columns, a liquid injection port, and a wick.

[0009] The laser power used for printing the upper plate, lower plate, side wall, support column and liquid injection port is 250 - 400 W, the scanning speed is 500 - 2000 mm / s, and the scanning pitch is 0.05 - 0.15 mm.

[0010] The laser power used for printing the capillary wick is 120 - 300 W, the scanning speed is 1000 - 3000 mm / s, and the scanning pitch is 0.10 - 0.30 mm.

[0011] The thickness of the upper plate, lower plate and side wall can be 0.1 - 10 mm.

[0012] The cross-section of the support column can be circular, elliptical, triangular or rectangular. The diameter, major axis or side length can be 1 - 10 mm.

[0013] The housing is a dense structure, enclosing an internal cavity to ensure the airtightness of the flat heat pipe. The support column is a dense structure, distributed in the internal cavity of the housing, connecting the upper and lower parts or left and right parts of the housing to ensure the strength of the flat heat pipe. The liquid injection port can be located at any part of the housing, and the internal pipe of the liquid injection port is connected to the internal cavity of the housing for filling the working medium and sealing after filling the working medium. The wick is a porous structure, covering the surface of the support column and the inner surface of the housing.

[0014] The upper plate and lower plate are parallel to the SLM processing plane, and the lower plate is in close contact with the processing platform or connected to the processing platform through supports. The lower part of the upper plate is in contact with the support column, side wall and capillary wick, and the contact area accounts for more than 80% of the projected area of the upper plate on the processing plane.

[0015] In the flat heat pipe structure, the axis of the support column can be perpendicular to the processing plane, connecting the upper plate and the lower plate; or parallel to the processing plane, connecting the side walls.

[0016] The connection between the support column and the upper plate, lower plate or side wall can be rounded with a radius of 0.1 - 2 mm.

[0017] More than 50% or all of the surface of the support column is in contact with the capillary wick.

[0018] When the axis of the support column is parallel to the processing plane, the part of the lower section plane less than 30° with the processing plane must be in contact with the capillary wick.

[0019] The capillary wick at the lower part of the upper plate or support column should be in contact with the support column or side wall by a conical surface or an inclined surface, and the included angle between the section plane of the conical surface or inclined surface and the processing plane is not less than 30°.

[0020] When the axis of the support column is perpendicular to the processing plane, the upper part of the lower plate contacts the support column, the side wall and the capillary wick, and the contact area accounts for more than 80% of the projected area of the lower plate on the processing plane. When the axis of the support column is parallel to the processing plane, the inner sides of the two side walls connected to the support column contact the support column, the side wall and the capillary wick, and the contact area accounts for more than 80% of the projected area of the side wall in the direction of the axis of the support column.

[0021] The capillary wick can be single-layer or multi-layer, and the thickness of each layer of the capillary wick is 0.05 - 10 mm.

[0022] The beneficial effect of this invention is that the flat heat pipe structure can be prepared by printing in a way that the upper plate and the lower plate are parallel to the processing plane, greatly improving the preparation efficiency. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the flat heat pipe described in Embodiment 1 of the present invention; Figure 2 It is a schematic structural diagram of the flat heat pipe described in Embodiment 2 of the present invention. Detailed Description of the Invention Embodiment 1

[0024] The external dimensions of the flat heat pipe are 80×60×10 mm. The thicknesses of the upper plate, the lower plate and the side wall are all 3 mm. The outer diameter of the liquid injection port is 4 mm and the inner diameter is 1 mm. The height of the central cavity between the upper plate and the lower plate is 4 mm. The axis of the support column is perpendicular to the processing plane and is arranged in an equilateral triangle pattern. The diameter of the support column is 3 mm, and the center distance between any two adjacent support columns is 6.5 mm. The entire surface of the support column is in contact with the capillary wick. The lower part of the upper plate is entirely in contact with the support column, the side wall or the capillary wick. The capillary wick at the lower part of the upper plate is connected to the side wall or the support column in a conical surface manner, and the angle between the tangent plane of the conical surface and the processing plane is 40°. It has a two-layer capillary wick structure. The first layer of capillary wick is adjacent to the upper plate, the lower plate, the side wall or the support column, and the second layer of capillary wick is adjacent to the internal cavity. The thickness of the first layer of capillary wick is 0.2 mm, and the thickness of the second layer of capillary wick except for the conical surface is 0.5 mm. The second layer of capillary wick at the lower part of the upper plate is connected to the side wall or the support column in a conical surface manner, and the angle between the tangent plane of the conical surface and the processing plane is 40°.

[0025] Using AlSi10Mg powder with a particle size of 15 - 53 μm as the raw material, printing is carried out on an SLM printer with a printing area of 100×100 mm. A layer thickness of 0.03 mm is adopted. For dense structures such as the upper plate, the lower plate, and the support column, an energy density of 70 J / mm 3 is used for printing, and an energy density of 30 J / mm 3 is used for printing the capillary wick. Prepared in the above manner, the printing height is 10 mm, sliced into 334 layers, and printing can be completed within 5 hours.

[0026] For flat heat pipes with the same size that do not adopt the structure described in this patent, it is necessary to adopt a 45° inclination to prevent significant deformation during the printing process. The printing height is at least 42.4 mm, sliced into about 1415 layers, and it takes at least 20 h to complete the printing. Example 2

[0027] The external dimensions of the flat heat pipe are 80×60×8 mm. The thicknesses of the upper plate, lower plate and side wall are all 2 mm. The outer diameter of the liquid injection port is 4 mm and the inner diameter is 1 mm. The height of the cavity in the middle of the upper plate and lower plate is 4 mm. The axes of the support columns are parallel to the processing plane and arranged in a square pattern. The cross-section of the support column is square with a side length of 2 mm, and the center distance between any two adjacent support columns is 5 mm. The entire surface of the support column is in contact with the capillary wick. The lower part of the upper plate is entirely in contact with the side wall or the capillary wick. The surfaces of the two side walls connected by the support column are all in contact with the support column, side wall and capillary wick. It has a single-layer capillary wick structure, and the thickness of the part of the capillary wick except the inclined surface is 0.2 mm. The capillary wicks at the lower part of the upper plate and the lower part of the support column are connected to the side wall in an inclined surface manner, and the angle between the inclined surface and the processing plane is 45°.

[0028] Using 304 stainless steel powder with a particle size of 5 - 30 μm for printing on an SLM printer with a printing area of 400×400 mm. Each version can print 60 flat heat pipes. With a layer thickness of 0.05 mm, the dense structures such as the upper plate, lower plate and support columns are printed with an energy density of 60 J / mm 3 and the capillary wick is printed with an energy density of 25 J / mm 3 Prepared in the above manner, the printing height is 60 mm, sliced into 1200 layers, and the printing of 60 flat heat pipes can be completed within 25 h.

Claims

1. A flat heat pipe structure prepared based on selective laser melting (SLM) technology, characterized in that: The flat plate heat pipe structure is composed of an upper plate, a lower plate, a side wall, a support column, a liquid injection port and a capillary core.

2. The flat plate heat pipe structure according to claim 1, characterized in that: The upper plate and the lower plate in the flat heat pipe structure are parallel to the plane of the SLM processing platform. The lower plate is closely attached to the processing platform, or connected to the processing platform by a support. The lower part of the upper plate is in contact with the support column, the side wall and the capillary core, and the contact area accounts for more than 80% of the projection area of ​​the upper plate on the processing plane.

3. The flat plate heat pipe structure according to claim 1 or 2, characterized in that: The axis of the support column in the flat heat pipe structure can be perpendicular to the processing plane, connecting the upper plate and the lower plate; it can also be parallel to the processing plane, connecting the side wall. The cross-section of the support column can be circular, elliptical, triangular or rectangular. The diameter, major axis or side length can be 1-10mm. The connection between the support column and the upper plate, lower plate or side wall can be connected with a fillet with a radius of 0.1-2mm. More than 50% or all of the surface of the support column is in contact with the capillary wick. When the axis of the support column is parallel to the processing plane, the portion of the lower section that is less than 30° from the processing plane must be in contact with the capillary wick.

4. The flat plate heat pipe structure according to claims 1, 2 and 3, characterized in that: The capillary core at the lower part of the upper plate or the support column should be in contact with the support column or the side wall by means of a conical surface or an inclined surface, and the angle between the section of the conical surface or the inclined surface and the processing plane should be not less than 30°.

5. According to the flat heat pipe structure of claims 1-4, when the axis of the support column is perpendicular to the processing plane, the upper part of the lower plate contacts the support column, the side wall and the capillary wick, and the contact area accounts for more than 80% of the projection area of ​​the lower plate on the processing plane. When the axis of the support column is parallel to the processing plane, the inner sides of the two side walls connected to the support column contact the support column, the side wall and the capillary wick, and the contact area accounts for more than 80% of the cross-sectional area of ​​the side wall.

6. The flat plate heat pipe structure according to claims 1-5, characterized in that: The capillary core may be single-layer or multi-layer, and the thickness of each layer of the capillary core is 0.05-10 mm.

7. The flat plate heat pipe structure according to claims 1-5, characterized in that: The thickness of the upper plate, the lower plate and the side wall may be 0.1-10 mm.

8. The flat plate heat pipe structure according to claims 1-5, characterized in that: The cross section of the support column can be circular, elliptical, triangular or rectangular, and the diameter, major axis or side length can be 1-10 mm.

9. A method for preparing a flat heat pipe structure according to any one of claims 1 to 8, characterized in that: It can be prepared by 3D printing using aluminum alloy powder, titanium alloy powder, stainless steel powder, or metal powder such as copper and copper alloy.

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