Abstract:
A process of connecting a header pipe of a heat exchanger to another heat exchanger part, including the steps of (a) providing a header pipe with a hole in its side and cladding material about its circumference, and a part with a groove with flux applied to the portion of the part to be joined to the header pipe, (b) positioning the header pipe and the part to align the header pipe hole and part groove, (c) inserting a rivet into the aligned header pipe hole and part groove, (d) locating a supporting rod in the header pipe and aligned with the rivet, and (e) hammering the part to warp the head of the rivet against the supporting rod and widen the circumference of the rivet in the hole and groove.

Description:
CROSS REFERENCE TO RELATED APPLICATION(S)  
       [0001]     Not applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable:  
       REFERENCE TO A MICROFICHE APPENDIX  
       [0003]     Not applicable.  
       TECHNICAL FIELD  
       [0004]     The present invention relates to a process for assembling a heat exchanger, and more particularly to a process for attaching fixtures to the header pipe.  
       BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIOR ART  
       [0005]     Heat exchangers for air circulating systems of automobiles, for example, are constructed with a header pipe installed on the heat exchanger core which has cooling fluid tubes and cooling fins. The brackets and other inlet/outlet fixtures for cooling liquid are initially attached to the header pipe on a heat exchanger frame during the assembly of such components, after which they often are permanently attached to the header pipe through brazing, while cladding material is applied.  
         [0006]     Various technical suggestions have heretofore been proposed to assist in initial assembly fo such heat exchangers. Korean Practical New Device Registration Number 10-1996-38332, for example, suggests creating a conjunctional vacuum between the tank of the header pipe and the bracket as they are aligned, including riveting after a rivet is inserted into the conjunctional vacuum. Korean Practical New Device Registration Number 10-1996-67450 has also suggested creating a conjunctional vacuum between the tank of the header pipe and the bracket as they are aligned. While maintaining this vacuum, the bottom portion of a conjunctional material is inserted into the tank or the bracket, and then is tightly fixed.  
         [0007]     The above technical suggestions can be advantageous when used with thin brackets and fixtures. However, they become problematic when the rivets and the conjunctional materials are applied to thick fixtures. In addition, since the rivet and the bottom portion of the conjunctional material are exposed on the exterior, it damages the external appearance.  
         [0008]     According to another technical suggestion, the header pipe is TIG welded to the header pipe and the other fixtures including brackets. However, with this method, if the electrical current fluctuates during the welding, the depth and the height of the bead will change, creating a problem with the bracket coming off during the core brazing. Moreover, in the case of large fixtures in which the entire circumferences of more than two parts must be welded, the cost of the method can be high.  
         [0009]     The present invention is directed toward overcoming one or more of the problems set forth above.  
       SUMMARY OF THE INVENTION  
       [0010]     In one aspect of the present invention, a process of connecting a header pipe of a heat exchanger to another heat exchanger part is provided, including the steps of (a) providing a header pipe with a hole in its side and cladding material about its circumference, and a part with a groove with flux applied to the portion of the part to be joined to the header pipe, (b) positioning the header pipe and the part to align the header pipe hole and part groove, (c) inserting a rivet into the aligned header pipe hole and part groove, (d) locating a supporting rod in the header pipe and aligned with the rivet, and (e) hammering the part to warp the head of the rivet against the supporting rod and widen the circumference of the rivet in the hole and groove.  
         [0011]     In one form of this aspect of the present invention, the hammering step also compresses the rim of the header pipe hole.  
         [0012]     In another form of this aspect of the present invention, the supporting rod has a curved surface at its contacting point to the rivet during the hammering step.  
         [0013]     In still another form of this aspect of the present invention, ⅕ to ½ of the length of the rivet is in the part groove before the hammering step. In a further form, the depth of the part groove is in the range of ⅕-½ of the entire length of the rivet before the hammering step.  
         [0014]     In yet another form of this aspect of the present invention, the rivet is one of a plain rivet, a round headed rivet and a rivet with knurling on the end in the part groove.  
         [0015]     In still another form of this aspect of the present invention, the rivet is round headed, and the supporting rod has a concave groove corresponding to the rivet round head at the portion that contacts the head of the rivet during the hammering step.  
         [0016]     In another aspect of the present invention, a process of connecting a header pipe of a heat exchanger to another heat exchanger part is provided, including the steps of (a) forming (I) a hole in the header pipe with cladding material about the hole circumference, and (ii) a groove in the part with flux applied to the portion of the part to be joined to the header pipe, (b) aligning the header pipe hole and the part groove with a rivet inserted in the aligned header pipe hole and part groove, (c) locating a supporting rod in the header pipe, and (d) hammering the part to warp the head of the rivet against the supporting rod and widen the circumference of the rivet in the hole and groove. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a cross-sectional view of a header pipe and part adapted for assembly according to the method of the present invention;  
         [0018]      FIG. 2  is a cross-sectional view showing the header pipe and the part being aligned with a rivet;  
         [0019]      FIG. 3  is a cross-sectional view showing riveting by hammering of the part according to the method of the present invention.  
         [0020]      FIG. 4  is a cross-sectional view after the riveting is completed;  
         [0021]      FIG. 5  is a cross-sectional view of an alternative embodiment of the present invention in which a rivet with a round head is used;  
         [0022]      FIG. 6  is a cross-sectional view similar to  FIG. 3 , but showing riveting by hammering of the part with the  FIG. 5  embodiment; and  
         [0023]      FIG. 7  is a cross-sectional view similar to  FIG. 3 , but of still another embodiment of the present invention in which a rivet with a knurled portion is used.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]     Broadly, according to the present invention, components of a heat exchanger are attached by, in a first phase, creating a hole in the header pipe with cladding material applied on its circumference, and creating a groove in the opposite part while flux is applied to the portion of the opposite part which will be fixed to the header pipe. Thereafter, a rivet is inserted into the hole and the groove while the header pipe and the opposite part are positioned with both the hole and the groove aligned. A supporting rod is then put into the header pipe facing the head of the rivet and, by hammering the part, the head of the rivet is warped to compress the rim of the pipe hole while also widening the circumference of the rivet until it fully fills the hole and the groove, resulting in complete tightness.  
         [0025]     The Figures illustrate this process.  
         [0026]      FIG. 1 , which shows a cross-sectional view of the first phase of the invention, illustrates hole  10  is created in the header pipe  12  of a heat exchanger (not shown). At the same time, a groove  20  is formed respectively in the assembly part  22 , matching the hole  10  of the header pipe  12 . The assembly part  22  (i.e., the part attached to the chassis of the heat exchanger) mounted to the header pipe  12  can be any bracket, or any inlet/outlet fixture in which the cooling fluid flows in/out.  
         [0027]     As mentioned above, with the hole  10  in the header pipe  12  and the groove  20  in the part  22 , cladding materials  30  can be applied both to the header pipe  12  and the joining section of the part  22  (since brazing will be performed later). Otherwise, cladding material  30  may be applied only to the joining section (which will be joined to the part  22  of the header pipe  12 ), with flux  40  applied to the joining section (which will be joined to the header pipe  12 ) of the part  22 . Thus, by applying either cladding material  30  or flux  40 , during the brazing, the clad  30  and the flux  40  will be melted by the heat. In the end this will result in tight adhesion.  
         [0028]     During the second phase of the process of the present invention, the header pipe  12  and the part  22  are positioned with the hole  10  of the header pipe  12  and the groove  20  of the part  22  aligned, and a rivet  50  is inserted through the hole  10  and the groove  20 .  
         [0029]     Thereafter in the third phase, as shown in  FIG. 3 , a supporting rod  60  is inserted into the header pipe  12  so as to contact the head of the rivet  50 , and the part  22  is hammered with a puncher  70  to perform a riveting process. The head portion of the rivet  50  which is contacted with the supporting rod  60  is warped by this process, filling the hole  10  and tightening the rim around the hole  10 . At the same time, as the circumference of the inserted portion of the rivet  50  in the groove  20  expands, it fully fills the groove  20 , as shown in the  FIG. 4 .  
         [0030]     The surface of the supporting rod  60  which connects to the rivet  50  may advantageously be curved according to the inner shape of the header pipe  12 . The attachment formed using a supporting rod  60  having such a surface will advantageously be tight since, when the part  22  is being hammered, the warped portion of the rivet  50  will tighten around the rim of the hole  10  of the header pipe  12  between the curved surface of the supporting rod  60  and inner surface of the header pipe  12 .  
         [0031]     It should be appreciated that, since the riveting was done inside the header pipe  12  and part  22 , none of the rivet portion  50  is externally exposed from either the header pipe  12  or the part  22 . In addition, since a groove  20  is made in part  22  instead of a hole, this method can be readily used with a heavy sectioned part where making a hole may be very difficult.  
         [0032]     It should also be appreciated that the diameters of the hole  10  in the header pipe  12  and the groove  20  in the part  22  should be chosen with consideration to the size of the applied rivet  50 . The diameter of the rivet  50  compared to the diameter of the hole  10  and the diameter of the groove  20  should be selected so that there is not too much looseness during riveting, to thereby ensure that the process of the present invention will result in secure and tight attachments. For example, during the process of inserting the rivet into the hole and the groove, the portion inserted into the groove  20  may advantageously be between about ⅕ to ½ of the total length of the rivet. If the inserted portion of the rivet  50  exceeds more than about ½ of the total length of the rivet  50 , the header pipe  12  and the part  22  may be damaged (due to the repetitive hammering of the part  22  in order to expand the circumference of the inserted portion of the rivet  50  sufficiently to fill the groove  20 ). Moreover, since there is limitation to the expansion of the circumference of the rivet  50 , if the inserted portion of the rivet  50  exceeds more than ½ of the total length of the rivet  50 , the desired tight adhesion will not occur. On the other hand, if the inserted length of the rivet  50  is less than about ⅕ of its total length, complete filling cannot be expected. In order to achieve the above-mentioned range, the groove  20  may be formed so that it has a depth according to the given range, or the size of the rivet  50  can be chosen according to the given range.  
         [0033]     In summary,  FIGS. 1-4  show one practical implementation of the invention of the present invention using a plain rivet  50 ,  FIGS. 5-7 , by contrast, illustrate the implementation of the present invention using different rivets, specifically, a rivet  80  having a round head  81  ( FIGS. 5-6 ) and a rivet  90  with knurling  91  ( FIG. 7 ).  
         [0034]     Thus, in the case of applying the round headed rivet  80  as shown on the  FIG. 5 , the supporting rod  60 ′ may advantageously include a corresponding concave groove  94  in the shape of the round head  81  of the rivet  80 . The rivet  80  then can be inserted through the header pipe  12  to the groove  20  of the part  22  as the head  81  of the rivet is already inserted to the concave groove  94  of the supporting rod  60 ′. After that, as shown in  FIG. 6 , the part  22  is hammered with the puncher  70  in the riveting process. It should be appreciated that, besides the round headed rivet  80 , various other types of rivet (e.g., an oval-headed rivet) could also be used within the scope of the present invention.  
         [0035]     As shown on the  FIG. 7  (where a rivet  90  with knurling  91  is used), the knurled portion  91  of the rivet  90  is inserted into the groove  20  of the part  22 . During the process of riveting, by hammering the part  22 , the knurled portion  91  will be caused to warp the inner surface of the groove  20 , creating a tight connection. At the same time, since the wide surface of the knurling  91  will fill the groove  20  more fully, it may create a more solid tightening than in the case of using a plain rivet.  
         [0036]     It should thus be appreciated that the attachment method between parts of the heat exchanger according to the present invention assures the very firm assembly of the header pipe and the part. During the process of the riveting, the circumference of the rivet expands, filling and joining tightly both the hole of the header pipe and the groove of the part. Likewise since this solid attachment is possible, making the riveting section in the center of the part will hold the assembly strongly enough, while at the same time reducing the cost. Furthermore, this invention will greatly improve the quality of the heat exchanger since the assembly part is adhered tightly and safely to the header pipe.  
         [0037]     Further, because a groove instead of a hole is made in the part, the present invention may be advantageously used with heavy sectioned parts where making a hole is very difficult. Moreover, since the riveting is done inside of both the header pipe and the part, no portion of the rivet is exposed to the exterior, thus preserving the external appearance.  
         [0038]     Still further, it should thus be appreciated that the present invention provides a method of attaching heat exchanger components at a low cost during the provisional assembly of various parts of the header pipe (including the brackets and the inlet/outlet fixtures of cooling fluid).  
         [0039]     Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the objects and advantages of the present invention and preferred embodiment as described above would be obtained.