Patent Publication Number: US-2012043067-A1

Title: Heat sink core member and its fabrication procedure

Description:
BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to heat sink fabrication technology and more particularly to a method of making a heat sink core member by extruding a predetermined mass of aluminum block into a tubular body having one close end wall and then punch-cutting the outside wall of the tubular body to form a plurality of densely distributed and equally spaced vertical retaining grooves for easy mounting of radiation fins. 
     (b) Description of the Prior Art 
     A radiation fin type heat sink generally comprises a tubular core member and a plurality of radiation fins. The radiation fins are radially spaced around the periphery of the tubular core member. Because the radiation fins are integrally formed with the periphery of the tubular core member, the fabrication of the heat sink is complicated, and the cost is high. Further, due to technical limitation, the radiation fins have a thick wall thickness. In consequence, the heat sink is heavy. Due to a limited number of radiation fins, the heat dissipation efficiency of this kind of heat sink is limited. 
     During application, the tubular core member is attached with its one end to the heat source (CPU or LED device). A heat pipe may be attached to enhance heat dissipation performance. Further, the tubular core member may be made in the shape of a round tube, rectangular tube or polygonal tube. 
     There are known heat sinks in which the radiation fins are soldered to the periphery of the tubular core member. However, it takes much time and labor to solder every radiation fin to the periphery of the tubular core member. Before soldering, an electroplating technique may be necessary so that different metal materials can be soldered together. Further, this fabrication procedure is not environmentally friendly. Further, solder-bonding will lower heat transfer efficiency. Further, a heat sink may be directly cut from a solid aluminum block. This method wastes much labor and time and will produce many waste materials, increasing the cost considerably. 
     Further, a heat sink core member may be directly extruded from an aluminum ingot. This method is to extrude an aluminum ingot into a tubular member having longitudinal grooves spaced around the periphery. The tubular member is than cut into tubular core members subject to the desired length. Radiation fins are than fastened to the longitudinal grooves of each tubular core member. This fabrication procedure still has drawbacks as follows:
         1. Due to technical limitations, the number of the longitudinal grooves of the extruded heat sink core member is limited, and therefore only a limited number of radiation fins can be fastened to the periphery of the heat sink core member. When the number of the longitudinal grooves is increased, the wall structure of the heat sink core member under extrusion may be damaged.   2. The finished heat sink core member is a hollow tubular member having two open ends. A plate member must be bonded to the heat sink core member to close its one end so that the blocked end of the heat sink core member can be attached to the heat source or used to support an attached member during application. However, because the plate member and the heat sink core member are not made integrally, a capillary effect will occur, lowering the heat transfer performance.       

     Therefore, it is desirable to provide a heat sink core member and its fabrication procedure that eliminates the drawbacks of the prior art designs and techniques. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a heat sink core member fabrication procedure for making a heat sink core member by means of preparing a predetermined mass of aluminum block, and then extruding the aluminum block through an extruding machine into a tubular body having one close end wall and then punch-cutting the outside wall of the tubular body to form a plurality of densely distributed and equally spaced vertical retaining grooves. Thus, radiation fins can easily be affixed to the vertical retaining grooves of the tubular body to form a high-performance heat sink. 
     Using the heat sink core member fabrication procedure for making a heat sink core member of this application, the finished heat sink core member has a close end wall. As a result, the invention prevents a capillary effect, thus effectively facilitating heat transfer. 
     In the heat sink core member fabrication procedure for making a heat sink core member of the present application, the punch-cutting step may include three substeps, i.e., the coarse punch-cutting substep to punch-cut the outside wall of said tubular body into a predetermined number of rough grooves, the fine punch-cutting substep to punch-cut each said rough groove into a fine groove, and the superfine punch-cutting substep to punch-cut each said fine groove. These substeps are performed automatically for facilitating the fabrication and saving the fabrication time and labor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a heat sink core member fabrication procedure in accordance with the present invention. 
         FIG. 2  is an alternate form of the heat sink core member fabrication procedure in accordance with the present invention. 
         FIG. 3  illustrates a circular aluminum block prepared according to the present invention. 
         FIG. 4  illustrates a rectangular aluminum block prepared according to the present invention. 
         FIG. 5  illustrates a round tubular body extruded according to the present invention. 
         FIG. 6  is a sectional view of  FIG. 5 . 
         FIG. 7  is a top view of  FIG. 5 . 
         FIG. 8  illustrates a rectangular tubular body extruded according to the present invention. 
         FIG. 9  is a sectional view of  FIG. 8 . 
         FIG. 10  is a top view of  FIG. 8 . 
         FIG. 11  is an oblique elevation of a round tube-like heat sink core member prepared according to the present invention. 
         FIG. 12  is a sectional view of  FIG. 11 . 
         FIG. 13  is a top view of  FIG. 11 . 
         FIG. 14  is an oblique elevation of a rectangular tube-like heat sink core member prepared according to the present invention. 
         FIG. 15  is a sectional view of  FIG. 14 . 
         FIG. 16  is a top view of  FIG. 14 . 
         FIG. 17  is a schematic sectional view, illustrating radiation fins inserted to the respective vertical retaining grooves of a round tube-like heat sink core member according to the present invention. 
         FIG. 18  corresponds to  FIG. 17 , illustrating the radiation fins affixed to the respective vertical retaining grooves. 
         FIG. 19  is an oblique elevation of a heat sink based on a round tube-like heat sink core member according to the present invention. 
         FIG. 20  is an oblique elevation of a heat sink based on a rectangular tube-like heat sink core member according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As described in  FIG. 1 , a predetermined mass of aluminum block  1  (see  FIG. 3  or  FIG. 4 ) is extruded through an extruding machine into a tubular body  10  having one close end wall  11  (see  FIGS. 5˜7  or  FIGS. 8˜10 ), and then the outside wall of the tubular body  10  is punch-cut to form a plurality of vertical retaining grooves  12  that are equally spaced around the periphery in a densely distributed manner (see  FIGS. 11˜13  or  FIGS. 14˜16 ), and thus a heat sink core member  100  is obtained. Radiation fins  200  can then be fastened to the retaining grooves  12  of the heat sink core member  100  (see  FIG. 17  or  FIG. 18 ) to form a heat sink  300  (see  FIG. 19  or  FIG. 20 ). 
     The heat sink core member fabrication procedure includes the steps of:
         (1) preparing a predetermined mass of aluminum block  1 ;   (2) extruding the aluminum block  1  through an extruding machine into a tubular body  10  having one close end wall  11 ; and   (3) punch-cutting the outside wall of the tubular body  10  to form a plurality of densely distributed and equally spaced vertical retaining grooves  12 .       

     As described in  FIG. 2 , the step of punch-cutting the outside wall of the tubular body  10  includes the substeps of coarse punch-cutting, fine punch-cutting and superfine punch-cutting. The coarse punch-cutting substep is to punch-cut the outside wall of the tubular body  10  into a predetermined number of rough grooves. The fine punch-cutting substep is to punch-cut each rough groove into a fine groove substantially close to the predetermined size. The superfine punch-cutting substep is to punch-cut each fine groove again, modifying the size of each fine groove into one respective finished vertical retaining groove  12 . By means of performing one coarse punch-cutting substep, at least one fine punch-cutting substep and at least one superfine punch-cutting substep, the outside wall of the tubular body  10  is rapidly and efficiently processed to form the desired, densely distributed and equally spaced vertical retaining grooves  12 . These substeps are performed automatically for facilitating the fabrication and saving much the fabrication time and labor. 
     Further, during the extrusion step, vertical ribs  13  are formed on the inside wall of the tubular body  10  (see  FIGS. 5˜7  or  FIGS. 8˜10 ). Further, a hole-drilling step may be performed to make a mounting hole  14  on each vertical rib  13  (see  FIG. 11  or  FIG. 14 ), for mounting of an attached member. One or more mounting holes may be formed in the close end wall  11  of the tubular body  10  for the mounting of an attached member. 
     Further, the tubular body  10  can be made in any of a variety of shapes and dimensions. For example, the tubular body  10  can be shaped like a round tube as shown in  FIGS. 5˜7 . Alternatively, the tubular body  10  can be shaped like a rectangular tube as shown in  FIGS. 8˜10 . 
     Further, the radiation fins  200  to be fastened to the tubular body  10  can be made in any of a variety of shapes and sizes. However, the radiation fins  200  must be configured for press-fitting into or riveting to the vertical retaining grooves  12 . 
     Further, the vertical retaining grooves  12  may be variously configured. Preferably, the outside wall of the tubular body  10  is so punch-cut that a first protruding portion  121  and a second protruding portion  122  are formed and disposed along two opposite lateral sides of each vertical retaining groove  12 . After one radiation fin  200  is inserted into one vertical retaining groove  12 , the adjacent first protruding portion  121  is deformed in the direction toward the adjacent second protruding portion  121  to have the radiation fin  200  be firmly seized in between the first protruding portion  121  and the second protruding portion  122  (see  FIG. 18 ). 
     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.