Abstract:
First, a heat pipe containing a work fluid is provided. The heat pipe is not pressed until the work fluid turns into a vapor phase so as to form a desired shape. The method can be employed to shape a round cross-section of a heat pipe into an oblate one.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The invention relates to heat pipes, particularly to manufacture of heat pipes. 
         [0003]    2. Related Art 
         [0004]    Usually, a heat pipe is provided with a round cross-section. But sometimes a heat pipe with an oblate cross-section made by a pressing process is required. In a conventional pressing process, a mold with a flat surface is needed to press the heat pipe. At the initial time of the pressing process, a linear contact is formed between the mold and pipe, and then it will progressively turn into planar contact. However, the linear contact tends to invite a problem of stress concentration. Thus, dents will be formed at the pressed portions, i.e., the pressed portions cannot keep flat. This will adversely affect the thermo-conductivity of the heat pipe. 
         [0005]    On the other hand, when a heat pipe is connected with a thermo-conductive seat, the heat pipe with round cross-section is embedded into a slot of the seat by pressing. The heat pipe will be deformed by pressure to fit the shape of the slot. However, this process will also suffer from the same problem. That is to say, dents will be formed in the pressed portions of the heat pipe. As abovementioned, the pressed portions must be as flat as possible so as to keep good thermo-conductivity. However, the dents on the pressed portions are disadvantageous to the thermo-conductivity. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the invention is to provide a method for manufacturing a depressed heat pipe, which can prevent the pressed portions of the heat pipe from forming dents so as to obtain a completely flat surface. 
         [0007]    To accomplish the above object, the method of the invention includes the steps of: 
         [0008]    a) providing a heat pipe containing a work fluid; 
         [0009]    b) vaporizing the work fluid; and 
         [0010]    c) pressing the heat pipe to form a depressed portion thereon. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a flowchart of the invention; 
           [0012]      FIG. 2  shows the first status of the first embodiment of the invention; 
           [0013]      FIG. 3  shows the second status of the first embodiment of the invention; 
           [0014]      FIG. 4  shows the third status of the first embodiment of the invention; 
           [0015]      FIG. 5  shows a finished product made by the first embodiment of the invention; 
           [0016]      FIG. 6  is a cross-sectional view along line  6 - 6  in  FIG. 5 ; 
           [0017]      FIG. 7  shows the first status of the second embodiment of the invention; 
           [0018]      FIG. 8  shows the second status of the second embodiment of the invention; 
           [0019]      FIG. 9  shows the third status of the second embodiment of the invention; and 
           [0020]      FIG. 10  shows a finished product made by the second embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    Please refer to  FIG. 1 , which is a flowchart of the invention. The invention provides a method for manufacturing a depressed heat pipe. The method is used for reshaping a round cross-section of a heat pipe into an oblate one. 
         [0022]    In the first embodiment of the invention, a heat pipe with a round cross-section is reshaped into an oblate one (i.e. two parallel depressed flat surfaces). Please refer to  FIGS. 1 and 2 . First, a heat pipe  1  containing a work fluid  10  is provided in step  51 , in which the heat pipe  1  is provided with a round cross-section. 
         [0023]    Secondly, the heat pipe  1  is heated up to vaporize the work fluid  10  in step S 2  and as shown in  FIG. 3 . In this step, the heat pipe  1  is heated up directly or indirectly and to a temperature of 80 to 200° C. 
         [0024]    The work fluid  10  in liquid phase is heated to turn into gas phase  10 ′. The heat pipe  1  is heated up directly or indirectly and to a temperature of 80 to 200° C. 
         [0025]    Finally, after the work fluid  10  has been vaporized, the heat pipe  1  is pressed to form a depressed portion in step S 3  and as shown in  FIG. 4 . Step S 4  can be performed by employing a mold  2  including an upper mold  20  and a lower mold  21 . In this embodiment, the pressing surfaces of the upper mold  20  and lower mold  21  are flat planes. The work fluid  10 ′ has been a vapor while the mold  2  is pressing the heat pipe  1 . Thus the vaporized work fluid  10 ′ may generate pressure to the heat pipe  1  to prevent the pressed portions  11  from denting. In this embodiment, two parallel pressed portions  11  are formed because both of the upper mold  20  and lower mold  21  are planar as shown in  FIGS. 5 and 6 . 
         [0026]      FIG. 7  shows the second embodiment of the invention. As can be seen in  FIG. 7 , the invention also can be applied in a heat pipe embedded in a seat. First, a heat pipe  1  containing a work fluid  10  is provided, in which the heat pipe  1  is provided with a round cross-section. And a seat to be connected with the heat pipe  1  is provided, in which the seat has a heated surface  30  and a slot  31  in the heated surface  30 . The slot  31  may be preferably applied with a thermo-conductive medium such as thermal grease. 
         [0027]    Secondly, the heat pipe  1  is heated up to vaporize the work fluid  10  as shown in  FIG. 8 . In this step, the heat pipe  1  is heated up directly or indirectly and to a temperature of 80 to 200° C. 
         [0028]    The work fluid  10  in liquid phase is heated to turn into gas phase  10 ′. The heat pipe  1  is heated up directly or indirectly and to a temperature of 80 to 200° C. 
         [0029]    Finally, after the work fluid  10  has been vaporized, the heat pipe  1  is pressed into a trough  31  and to form a pressed portion  12  coplanar with the heated surface  30  as shown in  FIGS. 9 and 10 . This step can be performed by employing a mold including an upper mold  40  and a lower mold  41 . In this embodiment, the pressing surface of the upper mold  20  is provided with a holding groove  410  for accommodating the seat  3 . The work fluid  10 ′ has been a vapor while the mold  2  is pressing the heat pipe  1 . Thus the vaporized work fluid  10 ′ may generate pressure to the heat pipe  1  to prevent the pressed portions  11  from denting. 
         [0030]    Therefore, the method of the invention can prevent a round heat pipe being pressed from denting. The pressed portions can be kept completely flat. The flat pressed portions can maintain good thermo-conductivity. As a result, a heat pipe which has been pressed still can perform its original effect and function. 
         [0031]    While the forgoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. As such, the appropriate scope of the invention is to be determined according to the claims.