US20110047796A1

US20110047796A1 - Method for manufacturing heat pipe with artery pipe

Info

Publication number: US20110047796A1
Application number: US12/632,772
Authority: US
Inventors: Cheng-Jen Liang; Jui-Wen Hung
Original assignee: Foxconn Technology Co Ltd
Current assignee: Foxconn Technology Co Ltd
Priority date: 2009-08-28
Filing date: 2009-12-07
Publication date: 2011-03-03
Also published as: CN102003902A

Abstract

An exemplary method for manufacturing a heat pipe includes the following steps: providing a tube, a mandrel and an artery pipe, the tube defining an opening at one end thereof, a wick structure being positioned on an inner surface of the tube, a slot being defined in an outer surface of the mandrel; inserting the mandrel and the artery pipe into the tube via the opening, the artery pipe being received in the slot; baking the tube with the mandrel and the artery pipe to make the artery pipe join the wick structure; drawing the mandrel out of the tube via the opening; and injecting a working media into the tube, and evacuating and sealing the tube.

Description

BACKGROUND

1. Technical Field
The disclosure generally relates to a method for manufacturing a heat pipe, and particularly to a method for manufacturing a heat pipe with an artery pipe.
2. Description of Related Art
Heat pipes are widely used in various fields for heat dissipation purposes due to their excellent heat transfer performance. Currently, a typical heat pipe includes a sealed tube made of thermally conductive material and a working fluid contained in the tube. The working fluid is employed to carry heat from one end of the tube, typically called an “evaporator section,” to the other end of the tube, typically called a “condenser section.” Preferably, a wick structure is provided inside the heat pipe, lining an inner wall of the tube, for drawing the working fluid back to the evaporator section after it is condensed at the condenser section.
During operation, the evaporator section of the heat pipe is maintained in thermal contact with a heat-generating component. The working fluid contained at the evaporator section absorbs heat generated by the heat-generating component and then turns into vapor. Due to the difference of vapor pressure between the two sections of the heat pipe, the generated vapor moves and thus carries the heat towards the condenser section where the vapor is condensed into condensate after releasing the heat into ambient environment via, for example, fins thermally contacting the condenser section. Due to the difference in capillary pressure which develops in the wick structure between the two sections, the condensate is then drawn back by the wick structure to the evaporator section where it is again available for evaporation.
Usually, an artery pipe is provided inside the heat pipe. The artery pipe enhances the capillary force to draw the condensate back and thereby avoid dry-out of the heat pipe. The artery pipe is sealed within the tube of the heat pipe, but is unfixed and can move freely in the tube. This can adversely affect vapor flow in the heat pipe. In addition, when such a heat pipe needs to be flattened to increase a contact surface with the heat-generating component, it is impracticable to ensure that the artery pipe is attached on a portion of the tube of the heat pipe aligning with the heat-generating component. Thus the performance of the heat pipe may be adversely affected.
What is needed, therefore, is a method for manufacturing a heat pipe which can overcome the described limitations.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a flow chart showing a method for manufacturing a heat pipe in accordance with one embodiment of the disclosure.

FIG. 2 is an exploded, isometric view of a tube, a cylindrical mandrel and an artery pipe used for manufacturing the heat pipe of FIG. 1.

FIG. 3 is similar to FIG. 2, but showing the cylindrical mandrel inserted in the tube, and the artery pipe still out of the tube.

FIG. 4 is similar to FIG. 3, but showing the artery pipe inserted in the tube after the cylindrical mandrel has been inserted in the tube.

FIG. 5 is a cross sectional view of the tube of FIG. 4, taken along line V-V thereof.

FIG. 6 is similar to FIG. 4, but with the cylindrical mandrel have been removed from the tube, and showing the tube marked.

FIG. 7 is similar to FIG. 6, but showing the tube flattened.

FIG. 8 is a cross sectional view of the tube of FIG. 7, taken along line VIII-VIII thereof.

FIG. 9 is an isometric view of a tube, a cylindrical mandrel and artery pipes used for manufacturing a heat pipe with a plurality of artery pipes.

DETAILED DESCRIPTION

FIG. 1 summarizes a method for manufacturing a heat pipe in accordance with one embodiment of the disclosure. The method is explained in detail as follows:
Referring also to FIG. 2, firstly, a tube 10, a cylindrical mandrel 20 and an artery pipe 30 are provided. The tube 10 is hollow and cylindrical, and is made of highly heat conductive metal, such as copper, and so on. The tube 10 defines an opening 11 at one end thereof. A wick structure 12 is layered on an inner surface of the tube 10. The wick structure 12 can be fine grooves defined in the inner surface of the tube 10, screen mesh or fiber inserted into the tube 10 and held against the inner surface of the tube 10, or sintered powders bonded to the inner surface of the tube 10 by a sintering process. The cylindrical mandrel 20 is made of metal which has high rigidity, a high melting point and low reactivity, such as steel, and so on. The mandrel 20 defines a longitudinal slot 21 in an outer surface thereof. The slot 21 extends through to both a front end surface and a rear end surface of the mandrel 20. A cross section of the slot 21 defines part of an ellipse. An outer diameter of the mandrel 20 is substantially equal to an inner diameter of the tube 10 with the wick structure 12 therein, and a length of the mandrel 20 is greater than that of the tube 10. The artery pipe 30 is hollow and cylindrical, and defines a channel 31 therein. A cross section of the artery pipe 30 is annular. The artery pipe 30 has an outer diameter slightly less than a width of the slot 21 of the mandrel 20, but greater than a depth of the slot 21 of the mandrel 20. The artery pipe 30 has a length substantially equal to that of the tube 10. The artery pipe 30 is formed by a plurality of copper wires woven together, each of the copper wires having a diameter of about 0.05 mm.
Referring also to FIG. 3, the mandrel 20 is inserted into the tube 10 via the opening 11, with one end of the mandrel 20 exposed out of the tube 10. An outer circumferential surface of the mandrel 20 is intimately in contact with the wick structure 12 of the tube 10. In particular, when the wick structure 12 is a screen mesh or fiber wick, or a sintered powder wick, the mandrel 20 can provide required pressure to compel the wick structure 12 to intimately contact the inner surface of the tube 10. Thus, heat generated by a heat-generating component (not shown) is transferred to the wick structure 12 from the tube 10 more easily.
Referring also to FIG. 4, the artery pipe 30 is horizontally inserted into the slot 21 and then moves along the slot 21 into the tube 10. Since the diameter of the artery pipe 30 is slightly greater than the depth of the slot 21, when the artery pipe 30 enters the tube 10, the artery pipe 30 is pressed by both the wick structure 12 and the mandrel 20 and thereby deforms slightly. Thus, when the artery pipe 30 is inserted in the tube 10, the artery pipe 30 is deformed to intimately contact with the wick structure 12. Referring also to FIG. 5, after the artery pipe 30 is inserted in the tube 10, the artery pipe 30 has an elliptic cross-section, and forms an arcuate contact surface 33 abutting the wick structure 12. A contact area between the contact surface 33 of the artery pipe 30 and the wick structure 12 is increased after the artery pipe 30 is deformed, whereby the capillary force generated by the artery pipe 30 and the wick structure 12 is improved.
The tube 10 with the mandrel 20 and the artery pipe 30 is then heated in a high temperature furnace (not shown) to make the artery pipe 30 join with the wick structure 12. During heating, the mandrel 20 is kept in the tube 10 to ensure that the artery pipe 30 is straight and extends along a longitudinal direction of the tube 10, and further ensure that the artery pipe 30 intimately contacts the wick structure 12.
Referring to FIG. 6, after the artery pipe 10 is baked to combine with the wick 12 of the tube 10, the mandrel 20 is drawn out of the tube 10 via the opening 11 of the tube 10. A marking 40 is engraved on an outer circumferential surface of each end of the tube 10, corresponding to a position of the artery pipe 30. Alternatively, the marking 40 can be formed on only one end of the tube 10 or at a middle of the tube 10.
Subsequent processes such as injecting a working media into the tube 10, and evacuating and sealing the tube 10, can be performed using conventional methods. Thus, a straight circular heat pipe is attained. A portion of the tube 10, where the markings 40 are formed, is finally flattened to form a flat-type heat pipe 50 which has a rectangular cross-section, as shown in FIGS. 7 and 8. The heat pipe 50 includes a top surface 51, and a bottom surface 52 in parallel with the top surface 51. The top and bottom surfaces 51, 52 are planar. The markings 40 are located on a middle axis (not shown) of the top surface 51, and the artery pipe 30 is aligned with the middle axis of the top surface 51.
In use, the top surface 51 of the heat pipe 50, with the markings 40, is attached to the heat-generating component. At this time, the artery pipe 30 aligns with the heat-generating component.
In the present method for manufacturing the heat pipe 50, the slot 21 is defined in the mandrel 20. Thus, the artery pipe 30 is accurately fixed on the wick structure 12 of the tube 10, in an orientation whereby a length of the artery pipe 30 is fixed along a corresponding length of the wick structure 12. The artery pipe 30 cannot move freely in the tube 10. This increases the flow of the working media in the tube 10, and improves the heat transfer performance of the heat pipe 50. In addition, the markings 40 are formed on the circumferential surface of the tube 10, and align with the artery pipe 30. Accordingly, it is easy to ascertain the position of the artery pipe 30 according to the markings 40. In use, the position of the heat pipe 50 can be adjusted to make sure that the artery pipe 30 aligns with the heat-generating component, by using the markings 40 as guides. This further ensures the best heat transfer performance of the heat pipe 50.
In alternative embodiments, the shape and size of the slot 21 of the mandrel 20 can be varied, thereby forming different kinds of artery pipes 30 in the heat pipe 50 to satisfy different heat dissipation requirements. Furthermore, the mandrel 20 can have more than one slot 21, so that more than one artery pipe 30 is fixed in the tube 10. The embodiment described below includes one example of such variations.
Referring to FIG. 9, in this embodiment, a mandrel 20 a longitudinally defines three slots 21 a in an outer circumferential surface thereof. Two of the slots 21 a are at one end of the mandrel 20 a, and the other slot 21 a is at the other opposite end of the mandrel 20 a. Each of the slots 21 a has a length less than that of the mandrel 20 a. Each of the slots 21 a accommodates one artery pipe 30 a. Thus, the heat pipe manufactured via this method includes three artery pipes 30 a in the tube 10, wherein two artery pipes 30 a are attached to one end of the wick structure 12, and another artery pipe 30 a is attached to the other opposite end of the wick structure 12.
It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

What is claimed is:

1. A method for manufacturing a heat pipe, comprising:

providing a tube, a mandrel and at least one artery pipe, the tube defining an opening at one end thereof, a wick structure being positioned on an inner surface of the tube, at least one slot being defined in an outer surface of the mandrel;

inserting the mandrel and the at least one artery pipe into the tube via the opening, the at least one artery pipe being received in the at least one slot;

baking the tube with the mandrel and the at least one artery pipe to make the at least one artery pipe join the wick structure;

drawing the mandrel out of the tube via the opening; and

injecting a working media into the tube, and evacuating and sealing the tube.

2. The method for manufacturing a heat pipe of claim 1, further comprising forming at least one marking on an outer surface of the tube at a position corresponding to the at least one artery pipe.

3. The method for manufacturing a heat pipe of claim 2, wherein the at least one marking comprises two markings formed at two ends of the tube, respectively.

4. The method for manufacturing a heat pipe of claim 2, further comprising flattening the tube at a position where the at least one marking is formed.

5. The method for manufacturing a heat pipe of claim 1, wherein the at least one slot of the mandrel has an elliptic cross-section, the at least one artery pipe being hollow and cylindrical, and having an outer diameter slightly less than a width of the at least one slot of the mandrel, but greater than a depth of the at least one slot of the mandrel, the at least one artery pipe being pressed by the wick structure and the mandrel to deform slightly when the at least one artery pipe and the mandrel are in the tube.

6. The method for manufacturing a heat pipe of claim 1, wherein the at least one slot is longitudinally defined in an outer circumferential surface of the mandrel, and extends through a front end surface and a rear end surface of the mandrel.

7. The method for manufacturing a heat pipe of claim 1, wherein the at least one slot comprises a plurality of slots located at two ends of the mandrel, respectively.

8. The method for manufacturing a heat pipe of claim 1, wherein the at least one artery pipe is formed by a plurality of metal wires woven together.

9. The method for manufacturing a heat pipe of claim 1, wherein the mandrel has an outer diameter substantially equal to an inner diameter of the tube with the wick structure, and a length greater than that of the tube.