Abstract:
A forming method for a heat dissipating structure is provided. According to the method, an extrudate is formed by extrution molding, wherein the extrudate includes protruding bending portions extending in parallel. Fins are extruded monolithically on the bending portions. One or more cut channels are formed by cutting the fins and the extrudate with a cutting tool. The cutting tool cuts the fins for forming a notch on each fin at first, and then cuts the bending portions for forming a cut-through slot on each bending portion, wherein each cut-through slot is formed for cooling air flowing through two side of the extrudate. By cutting the bending portions and the fins by the cutting tool at the same time, a large number of cut-through slots are formed in despite of the existence of the fins, and the performance of heat dissipation is enhanced.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to heat dissipation, more particularly, to a heat dissipating structure formed by extrusion molding having enhanced air cooling performance. 
     2. Related Art 
     Referring to  FIGS. 1A and 1B , an air-cooling heat dissipating structure  1  in the prior art is shown. The air-cooling heat dissipating structure  1  essentially includes a substrate  2  and fins  3  formed on the substrate  2 . The substrate  2  is provided for contacting a heat source, or serves as a casing to enclose a heat generating member. An inner surface of the substrate  2  absorbs heat of a heat source  4  or a heat generating member  5  through heat conduction or heat convection, and an outer surface of the substrate  2  exchanges heat with ambient air to dissipate heat through heat convection. The fins  3  are disposed on the outer surface of the substrate  2  and arranged in parallel. The fins  3  are provided for increasing the total surface area for heat exchange, to enhance the heat convection performance of the air-cooling heat dissipation structure. 
     In general, the heat dissipating structure in the prior art is fabricated by various methods, such as machining, die casting, extrusion molding, and combination process. The extrusion molding method is widely applied to fabricate members of a uniform cross-sectional shape, due to its high production rate and simple processes. The extrusion molding method using aluminum or aluminum alloy with a relatively low melting point is also referred to as an aluminum extrusion molding method. 
     As aforementioned, the air-cooling heat dissipating structure is applied to serve as a casing to enclose a heat generating member. The heat generated by the heat generating member is indirectly dissipated outside through the air-cooling heat dissipating structure. The heat generating member is also directly cooled by air flowing into the casing to achieve an enhanced heat dissipation performance. In order to allow the circulation of the air flows, air vents formed on the casing are required to improve the air circulation effect. 
     However, the extrusion molding method can only be used to fabricate continuous structures having a uniform cross-sectional area. If the extruded direction of the extrusion molding is defined as a longitudinal direction, through-holes penetrating the extrudate in a direction perpendicular to the longitudinal direction cannot be formed by extrusion molding. If it is intended to form air vents by punching processing, the punching tool is unable to punch holes on the substrate  2  due to the fins  3  protruding from the heat dissipating structure  1 . A drill bit can be used to drill holes on the substrate  2 , but only one air vent can be done in each process. When the heat dissipating structure  1  must be studded with air vents, the use of a drill bit for drilling holes may require a lot of processing time, and thus fails to meet the demand on yield. Therefore, an enclosed casing fabricated by an extruded heat dissipating structure can only introduce cooling air flows in and exhaust hot air out through the air vents opened on the front and rear panels thereof, so that it is difficult to promote the circulation of the cooling air flows to enhance the air-cooling effect. 
     SUMMARY OF THE INVENTION 
     In the prior art, the problem that the existence of the fins causes difficulties on rapidly producing ventilated structures. By forming cut channels, the present invention rapidly forms massive cut through slots on a heat dissipating structure that has fins extended outward, thereby enhancing the air-cooling efficiency of the heat dissipating structure. 
     In one aspect of the present invention, a heat dissipating structure comprises an extrudate, multiple fins and one or more cut channel. The extrudate includes multiple protruding bent portions extending externally in parallel. The fins extend in parallel with the bent portions. One or more of the fins is disposed on one of the bent portions. The cut channel includes an notch forming on at least one of the fins and a cut-through slot forming on at least one of the bent portions; wherein the notch and the cut-through slot of the cut channel are coplanar. 
     In another aspect of the present invention, a method of forming a heat dissipating structure comprises the following steps. First of all, extrude a heat dissipating structure including multiple bent portions and multiple fins. The bent portions protrude outward and are in parallel with the fins. One or more of the fins is disposed on one of the bent portions of the heat dissipating structure. Then, cut the heat dissipating structure to form one or more cut channel. The cut channel includes an notch forming on one or more of the fins and a cut-through slot forming on one or more of the bent portions. It is to be disclosed be the present invention that the notch and the cut-through slot of the cut channel are coplanar. 
     These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. It is to be understood that both the foregoing general description and the following detailed description are examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below for illustration only, and thus is not limitative of the present invention, and wherein: 
         FIG. 1A  is a cross-sectional view of a heat dissipating structure in the prior art; 
         FIG. 1B  is a perspective view of a heat dissipating structure in the prior art; 
         FIGS. 2 and 3  are perspective views of a heat dissipating structure according to a first embodiment of the present invention; 
         FIG. 4  is a top view of the heat dissipating structure according to the first embodiment of the present invention; 
         FIG. 5A  is a cross-sectional view along line A-A′ in  FIGS. 3 and 4 ; 
         FIG. 5B  is a cross-sectional view along line B-B′ in  FIGS. 3 and 4 ; 
         FIGS. 6A ,  6 B, and  6 C are cross-sectional views of the first embodiment of the present invention, showing steps of forming the heat dissipating structure; 
         FIG. 7  is a perspective view of a casing formed according to the first embodiment of the present invention; 
         FIGS. 8 and 9  are perspective views of a heat dissipating structure according to a second embodiment of the present invention; 
         FIGS. 10 and 11  are cross-sectional views of the second embodiment; 
         FIGS. 12 and 13  are cross-sectional views of the second embodiment of the present invention, showing steps of forming the heat dissipating structure; 
         FIGS. 14 and 15  are perspective views of a heat dissipating structure according to a third embodiment of the present invention; 
         FIGS. 16 and 17  are cross-sectional views of the third embodiment; 
         FIGS. 18 ,  19 , and  20  are cross-sectional views of the third embodiment of the present invention, showing steps of forming the heat dissipating structure; 
         FIG. 21  is a cross-sectional view of a fourth embodiment of the present invention; 
         FIG. 22  is a cross-sectional view of a fifth embodiment of the present invention; 
         FIG. 23  is a cross-sectional view of a sixth embodiment of the present invention; 
         FIG. 24  is a cross-sectional view of a seventh embodiment of the present invention; and 
         FIG. 25  is a cross-sectional view of an eighth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description refers to the same or the like parts. 
     Referring to  FIGS. 2 ,  3 , and  4 , a heat dissipating structure  100  according to a first embodiment of the present invention is shown. The heat dissipating structure  100  includes an extrudate  110  and a plurality of fins  120 , wherein the extrudate  110  and the fins  120  are formed monolithically by extrusion molding, and cooling air can flow through the extrudate  110  to enhance the air-cooling effect. 
       FIG. 5A  is a cross-sectional view along line A-A′ in  FIGS. 3 and 4 . As shown in  FIG. 5A , the extrudate  110  is formed by extrusion molding, the extrudate  110  can be a single sheet or a tubular structure. The extrudate  110  includes a plurality of bent portions  111  and a plurality of connecting portions  112  disposed alternately, and the bent portions  111  and connecting portions  112  extend in a longitudinal direction of the extrudate. The connecting portions  112  are provided for connecting the adjacent bent portions  111 , and the bent portions  111  protrude from a surface of the extrudate  110 . Since the extrudate  110  is formed by the extrusion molding, the bent portions  111  extend in parallel along the longitudinal direction of the extrudate  110 . The aforementioned longitudinal direction is a direction which the extrudate  110  is extruded along in the extrusion molding. 
     Referring to  FIG. 5A , the extrudate  110  and the fins  120  are simultaneously formed by the extrusion molding, wherein the fins  120  are monolithically formed on an outer surface of the extrudate  110 . The fins  20  increase the total surface area for heat dissipation of the heat dissipating structure. Since the fins  120  are formed bye extrusion molding and extruded along the longitudinal direction, the fins  120  continuously extend in parallel with the bent portions  111  and the connecting portions  112 . The fins  120  are respectively disposed on the bent portions  111  and the connecting portions  112 . 
       FIG. 5B  is a cross-sectional view along line B-B′ in  FIGS. 3 and 4 . As shown in  FIG. 5B , after monolithically forming the extrudate  110  and the fins  120  by extrusion, a cutting process is performed. The extrudate  110  and the fins  120  of the heat dissipating structure  100  are cut by a cutting tool  900  to form a plurality of cut channels  130 . The cutting direction of the cut channel  130  males an angle with respect to the longitudinal direction of the extrudate  110 , namely, the cutting direction is not in parallel with the longitudinal direction of the extrudate  110 . Each cut channel  130  respectively forms an notch  131  on each fin  120  and meanwhile form a cut-through slot  132  on each bent portion  111 . 
     Referring to  FIGS. 6A ,  6 B, and  6 C, each cut channel  130  is formed by the cutting tool  900  cutting in a straight line with a gradually increasing cutting depth D, wherein the cutting depth D is the feed travel of the cutting tool  900  toward the extrudate  110 . In each cut channel  130 , the notch  131  and the cut-through slot  132  are formed by a single motion of the same cutting tool  900 , so that the notch  131  and the cut-through slot  132  are coplanar. As the fins  120  are formed on the surface of the extrudate  110  and with front edges located outside the top edges of the bent portions  111 , the cutting tool  900  will cut the fins  120  in advance when fed toward the surface of the extrudate  110 , thus forming the notches  131  on the fins  120 . 
     Then, the cutting tool  900  is brought into contact with the top edges of the bent portions  111  and cuts the bent portions  111 , so as to form the cut-through slots  132  on the bent portions  111 . The feed travel from the point that the cutting tool  900  is brought into contact with the top edges of the bent portions  111  to a point that the feeding of the cutting tool  900  is stopped is regarded as the cutting depth D. Such a cutting depth D is also equal to a distance from the outermost to the innermost edge of the cut-through slot  132 . In order to prevent the cut channels  130  formed by the cutting tool  900  from cutting off the extrudate  110 , junctions between the adjacent bent portions  111  are required to reserved. In this embodiment, the junctions between the adjacent bent portions  111  are the connecting portions  112 , such that the cutting tool  900  may not cut off the connecting portions  112 . That is, the cutting depth D of each cut-through slot  132  is smaller than the height of the bent portion  111  protruding from the connecting portion  112 , so as to prevent the connecting portion  112  from being cut off by the cutting tool  900 . 
     If bottom edges of the cut channels  130  are defined as cutting lines, a minimum cutting line Hmin can be defined at the highest point of the inner side faces of the bent portions  111 , and a maximum cutting line Hmax can be defined on the top faces of the connecting portions  112 . Cutting lines formed by the cutting tool  900  on the extrudate  110  lie between the minimum cutting line Hmin and the maximum cutting line Hmax, such that the cut-through slots  132  can be formed by the cutting tool  900  on the bent portions  111  without cutting off the connecting portions  112 . 
     The cut channels  130  are formed by the single cutting tool  900  to rapidly form the cut-through slots  132  on the extrudate  110  for the cooling air flows to pass through. Since, the cooling air flows can quickly flow through the extrudate  110 , the convection heat transfer is enhanced. 
     Referring to  FIG. 7 , the heat dissipating structure  100  can be fabricated into an enclosed or semi-enclosed casing. For example, the heat dissipating structure  100  is fabricated into a tubular structure surrounded by a plate and used as a casing of an electronic apparatus. In the heat dissipating structure  100 , heat is absorbed through the inner side face of the extrudate  110 , and dissipated through the outer surface thereof and the fins  120 . Meanwhile, the cut-through slots  132  allow the air flows to directly pass through the heat dissipating structure  100 , thus enhancing the heat dissipation effect. 
       FIGS. 8 ,  9 ,  10 , and  11  a heat dissipating structure  200  according to a second embodiment of the present invention is shown. The heat dissipating structure  200  includes an extrudate  210  and a plurality of fins  220 , wherein the extrudate  210  and the fins  220  are monolithically formed by extrusion molding. The extrudate  210  includes a plurality of bent portions  211  and a plurality of connecting portions  212  disposed alternately, and the bent portions  211  and connecting portions  212  extend in a longitudinal direction. The connecting portions  212  are provided for connecting the adjacent bent portions  211 , and the bent portions  211  protrude from a surface of the extrudate  210 . The bent portion  211  includes a first protruding portion  2111  and a second protruding portion  2112  adjacent to each other on the cross-section, wherein the height of the first protruding portion  2111  protruding from the connecting portions  212  is larger than that of the second protruding portion  2112  protruding from the connecting portions  212 . The fins  220  are disposed in parallel with the bent portions  211 , and are respectively disposed on the bent portions  211  and the connecting portions  212 . The fins  220  on the bent portions  211  are disposed on the first protruding portions  2111 , or the second protruding portions  2112 . 
     Referring to  FIGS. 12 and 13 , the heights of the cutting lines of cut channels  230  determine whether cut-through slots  232  can be formed as well as cutting depths D of the formed cut-through slots  232 . In the second embodiment, the heights of the cutting lines further determine the range of forming the cut-through slots  232 . 
     Referring to  FIG. 12 , when reaching a first cutting line H 1 , the edge of the cutting tool  900  is located between the top edges of the first protruding portions  2111  and the second protruding portions  2112 , and only the first protruding portions  2111  is cut by the cutting tool  900 . At this point, the cut-through slots  232  are formed on the first protruding portions  2111 . 
     Referring to  FIG. 13 , when reaching a second cutting line H 2 , the edge of the cutting tool  900  passes through the top edges of the first protruding portions  2111  and the second protruding portions  2112 , and both the first protruding portions  2111  and the second protruding portions  2112  are cut. At this point, the cut-through slots  232  are formed on the first protruding portions  2111  and further extend to the second protruding portions  2112 , thereby enhancing the overall porosity of the cut-through slots  232 . 
     Referring to  FIGS. 14 ,  15 ,  16 , and  17 , a heat dissipating structure  300  according to a third embodiment of the present invention is shown. The heat dissipating structure  300 , similar to that of the first embodiment, includes an extrudate  310  and a plurality of fins  320 , wherein the extrudate  310  and the fins  320  are formed monolithically. The extrudate  310  includes a plurality of bent portions and a plurality of connecting portions  312  disposed alternately, and the bent portions and the connecting portions  312  extend in a longitudinal direction of the extrudate  310 . The connecting portions  312  are provided for connecting the adjacent bent portions, and the bent portions protrude from a surface of the extrudate  310 . The heights of the bent portions protruding from the connecting portions  312  are unequal. The fins  320  are in parallel with the bent portions, and are respectively disposed on the bent portions and the connecting portions  312 . 
     Referring to  FIGS. 18 ,  19 , and  20 , the heights of the cutting lines of cut channels  330  determine whether cut-through slots  332  are formed at the bent portions by the cutting tool  900  as well as the cutting depths of the cut-through slots  332 . The heights of the bent portions are unequal. When the cutting tool  900  is fed toward the surface of the extrudate  310 , the fins  320  are cut at first, then the bent portions having relative higher height are cut to form the cut-through slots  332 , and afterward the bent portions  311  having relative lower height are cut. In the third embodiment, the bent portions at least include a first bent portion  3111 , a second bent portion  3112 , and a third bent portion  3113 . The first bent portion  3111 , the second bent portion  3112 , and the third bent portion  3113  are designated for illustration, instead of limiting the number of the bent portions. 
     Referring to  FIG. 18 , when the cutting tool  900  is continuously fed to make the cutting depths of the cut channels  330  reach a first cutting line H 1 , in addition to forming the notches  331  on the fins  320 , only the first bent portion  3111 , on which has the highest height, is cut to form cut-through slots  332 . 
     Referring to  FIG. 19 , when the cutting tool  900  is continuously fed to make the cutting depths of the cut channels  330  reach a second cutting line H 2 , the cut channels  330  simultaneously penetrate the first bent portion  3111  and the second bent portion  3112  to form the cut-through slots  332 . 
     Referring to  FIG. 20 , when the cutting tool  900  is continuously fed to make the cutting depths of the cut channels  330  reach a third cutting line H 3 , the first bent portion  3111 , the second bent portion  3112 , and the third bent portion  3113  are all cut to form the cut-through slots  332 . 
     In the present invention, it is not necessary for forming cut-through slots at all the bent portions. Whether the cut-through slots are formed or not depends on the cutting depths of the cut channels and the heights of the bent portions. According to the third embodiment, the number of the cut-through slots to be formed is determined by the cutting depths and the height differences of the bent portions. 
     In the first to the third embodiment, the cross-sectional area of the bent portions are approximately rectangular (in the first and third embodiments) or a combination of a plurality of rectangles (in the second embodiment). However, the cross-sectional areas of the bent portions are not limited to be rectangular, but can be of any shape protruding from the extrudate. The shape of the cross-sectional area of the bent portion is determined according to the consideration whether it can be easily extrusion-molded. 
     Referring to  FIG. 21 , a heat dissipating structure  400  according to a fourth embodiment of the present invention is shown. The heat dissipating structure  400  includes an extrudate  410  and a plurality of fins  420 , wherein the extrudate  410  and the fins  420  are monolithically formed. The extrudate  410  includes a plurality of bent portions  411  and a plurality of connecting portions  412 , the bent portion  411  and connecting portion  412  are disposed alternately and extend in a longitudinal direction of the extrudate  410 . The connecting portions  412  are provided for connecting the adjacent bent portions  411 , and the bent portions  411  protrude from a surface of the extrudate  410 . The fins  420  are disposed in parallel with the bent portions  411 , and are respectively disposed on the bent portions  411  and the connecting portions  412 . In the fourth embodiment, the cross-sectional areas of the bent portions  411  are quadrangular of any form. 
     Referring to  FIGS. 22 and 23 , a heat dissipating structure  500  according to a fifth embodiment and a heat dissipating structure  600  according to a sixth embodiment of the present invention are shown. The heat dissipating structure  500 ,  600  includes an extrudate  510 ,  610  and a plurality of fins  520 ,  620 , wherein the extrudates  510 ,  610  are monolithically formed with the fins  520 ,  620 . The extrudate  510 ,  610  includes a plurality of bent portions  511 ,  611  and a plurality of connecting portions  512 ,  612 . In the fifth and sixth embodiments, the cross-sectional areas of the bent portions  511  and  611  are respectively arc-shaped and triangular. 
     Referring to  FIG. 24 , a heat dissipating structure  700  according to a seventh embodiment of the present invention is shown. The heat dissipating structure  700  includes an extrudate  710  and a plurality of fins  720 , wherein the extrudate  710  and the fins  720  are monolithically formed. The extrudate  710  includes a plurality of protruding bent portions  711  in parallel with each other. The cross-sectional areas of the bent portions  711  are triangular. 
     The adjacent bent portions  711  are connected to each other at edges. The fins  720  are formed on the bent portions  711 , or on joining portions between the adjacent bent portions  711 . Therefore, when the cutting tool is used to form cut channels, junctions  711   a  between the adjacent bent portions  711  are required to be reserved. A minimum cutting line Hmin is defined at the highest point of the inner surface of the bent portions  711 , and a maximum cutting depth Hmax is defined at the lowest point of the outer surfaces of the bent portions  711 . The cutting lines for the cutting tool to cut the bent portions  711  lies between the minimum cutting depth Hmin and the maximum cutting depth Hmax, such that cut-through slots  732  are formed on the bent portions  711  without cutting off the junctions  711   a  between the adjacent bent portions  711 . 
     Referring to  FIG. 25 , a heat dissipating structure  800  according to an eighth embodiment of the present invention is shown. The heat dissipating structure  800  is similar to that of the seventh embodiment, and only differs in that the cross-sectional areas of the bent portions  811  of the eighth embodiment are arc-shaped. 
     Additional advantages and modifications will readily occur to those proficient in the relevant fields. The invention in its broader aspects is therefore not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.