Patent Publication Number: US-8973420-B2

Title: Corrugated fin manufacturing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2010-34932, filed on 19 Feb. 2010, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The present invention relates to a corrugated fin manufacturing apparatus that molds a corrugated fin where a plurality of ribs formed in a plate-like body made of metal are erected at predetermined intervals. 
     BACKGROUND 
     One example of a corrugated fin is depicted in  FIG. 15 . Note that the corrugated fin depicted in the drawing is an example of a plate fin where ribs are erected perpendicular to a plate-like body. The corrugated fin  10  has a plurality of consecutive ribs  12  formed in a metal plate-like body  9  made of aluminum or the like, and is mainly used in a heat exchanger in a vehicle radiator, an air conditioner, an EGR, or the like. 
     The construction disclosed in Patent Document 1 can be given as one example of a manufacturing apparatus for manufacturing the corrugated fin  10 . This manufacturing apparatus is capable of molding the ribs one at a time in a single pressing where a punch and a die are closed by a single press operation of a press apparatus. 
     When manufacturing the corrugated fin  10 , the plate-like body used as a material is drawn in between the punch and die, and if a plurality of punches and dies are used to simultaneously mold a plurality of ribs, the plate-like body will become pulled at both ends between the adjacent punches and dies, resulting in the risk of thinning and snapping of the ribs. For this reason, it has been difficult to simultaneously operate a plurality of punches and dies to simultaneously mold a plurality of ribs. 
     On the other hand, Patent Document 2 discloses a construction where the die is divided in the horizontal direction and is provided so as to be movable. With this construction, since the die that moves in the horizontal direction holds the side surfaces of the ribs, thinning and snapping of the ribs due to the plate-like body being pulled at both ends between the punches and dies are prevented. 
       FIG. 16  depicts a conventional corrugated fin manufacturing apparatus for forming one rib by a single mold closing operation. 
     On the downstream side in the conveying direction of the plate-like body  9 , a pilot punch  13   a  is disposed on the upper mold so as to be energized downward by an energizing means such as a spring. When a mold closing operation begins, the pilot punch  13   a  is lowered before the other punch and, in combination with the die of the lower mold, enters a rib that has already been formed by the previous mold closing operation to position the plate-like body  9 . 
     A machining punch  13   b  is disposed upstream of the pilot punch  13   a  so as to be energized downward by an energizing means such as a spring. When a mold closing operation begins, the machining punch  13   b  is lowered following the pilot punch  13   a  to press the plate-like body  9  that has been positioned by the pilot punch  13   a  onto the die  16  of the lower mold and thereby form a rib. A pressing portion  15  for applying pressure from above onto a part of the plate-like body  9  that has not been machined into ribs is formed on the upstream-side surface of the machining punch  13   b.    
     A plurality of concaves are formed in the die  16  of the lower mold. A concave that is downstream in the conveying direction of the plate-like body  9  is a pilot concave  16   a  into which the pilot punch  13   a  enters. A machining concave  16   b  into which the machining punch  13   b  enters to machine a rib is formed on the upstream side of the pilot concave  16   a . A mounting portion  17  with a flat upper surface onto which a lower surface of the unmachined part of the plate-like body  9  that is pressed by the pressing portion  15  of the machining punch  13   b  is mounted is formed on the upstream side of the machining concave  16   b.    
     Since the plate-like body  9  is pulled between the machining punch  13   b  and the machining concave  16   b  of the die while the machining punch  13   b  and the machining concave  16   b  are forming a rib  12 , the part that has not been machined into ribs bends upward. From the formation of a rib  12  onwards, the pressing portion  15  of the machining punch  13   b  gradually presses the upwardly bent unmachined part downward toward the die so that at a bottom dead center, the unmachined part is pressed between the pressing portion  15  of the machining punch  13   b  and the mounting portion  17  of the die  16 , resulting in the unmachined part becoming flat. 
     Patent Document 1 
     Japanese Laid-Open Patent Publication No. H04-371322 
     Patent Document 2 
     Japanese Laid-Open Patent Publication No. H09-155461 
     SUMMARY 
     As described above, the pressing portion  15 , which presses down the part of the plate-like body  9  that has not been machined into ribs and is bent upward to make the unmachined part flat, is formed on the conventional machining punch  13   b . With the construction of the conventional machining punch  13   b , at the same time as the formation of a rib  12  is completed, the pressing portion  15  presses the unmachined part onto the mounting portion  17  of the die  16  to make the unmachined part flat. Accordingly, even while a rib  12  is being molded, the pressing portion  15  presses the bent unmachined part progressively downward. 
     This means that even though the unmachined part needs to be sufficiently drawn in between the machining punch  13   b  and the machining concave  16   b  from the start of formation of a rib onwards, since the pressing portion  15  contacts the unmachined part and presses the unmachined part downward, even though force acts to draw the unmachined part in between the machining punch  13   b  and the machining concave  16   b , there is increased resistance due to contact with the pressing portion  15 , which means that the unmachined part is not sufficiently supplied between the machining punch  13   b  and the machining concave  16   b  during the machining of a rib. This results in the risk of the ribs thinning and snapping due to the unmachined part not being sufficiently drawn in. 
     The present invention was conceived in view of the problem described above and it is an object of the present invention to provide a corrugated fin manufacturing apparatus that is capable of reliably drawing in the unmachined part of the plate-like body and preventing thinning and snapping of ribs. 
     A corrugated fin manufacturing apparatus for forming a corrugated fin with a plurality of ribs from a plate-like body made of metal, the corrugated fin manufacturing apparatus comprising: a lower mold; an upper mold capable of moving toward and away from the lower mold; a die that is provided on the lower mold and includes a concave; a machining punch that is inserted into the concave of the die to form a rib when the upper mold and the lower mold are closed, wherein the machining punch is shaped so that when the machining punch enters the concave of the die, the machining punch does not cause resistance to drawing in of a part of the plate-like body that is present outside the concave of the die and has not been machined into ribs during formation of a rib; a mounting portion that is formed on the die upstream of the concave in a conveying direction of the plate-like body and on which the part of the plate-like body that has not been machined into ribs is mounted; and a flat punch that is provided upstream of the machining punch in the conveying direction of the plate-like body, wherein when a rib is being formed by the machining punch and the concave of the die, the flat punch does not cause resistance to drawing in of the part of the plate-like body that has not been machined into ribs during formation of a rib, and wherein the flat punch moves toward the mounting portion of the die after formation of a rib to press down the part of the plate-like body that has not been machined into ribs and, in combination with the mounting portion, press and flatten the part of the plate-like body that has not been machined into ribs. By using the above construction, the part that has not been machined into ribs is drawn between the machining punch and the die without resistance while the machining punch and the die are machining a rib. The flat punch starts to press and cause resistance to the part that has not been machined into ribs only after the formation of a rib has been completed, and operates to flatten such part. This means that while a rib is being formed, the part that has not been machined into ribs is sufficiently drawn in between the machining punch and the die, which means it is possible to prevent thinning and snapping of the ribs. 
     When the machining punch is shaped so that when the machining punch enters the concave of the die, the machining punch does not come into contact with the part of the plate-like body that has not been machined into ribs during formation of a rib. 
     The machining punch is shaped so that when the machining punch enters the concave of the die, the machining punch does not cause resistance to drawing in of the part of the plate-like body that has not been machined into ribs during formation of a rib even when the machining punch comes into contact with the part. 
     When a rib is being formed by the machining punch and the concave of the die, the flat punch is positioned so as to not come into contact the part of the plate-like body that has not been machined into ribs. 
     When the flat punch is shaped so as to not cause resistance to drawing in of the part of the plate-like body that has not been machined into ribs during formation of a rib even when the flat punch comes into contact with the part. 
     A plurality of concaves for forming ribs are provided in the die, the corrugated fin manufacturing apparatus comprises a plurality of machining punches that are capable of successively moving toward the die in one closing of the upper mold and the lower mold, the mounting portion is provided upstream in the conveying direction of the plate-like body of a final concave on the die for forming a final rib which is formed last, the respective machining punches are shaped so that when a next machining punch enters a concave of the die to form a next rib, the machining punches do not cause resistance to drawing in of a part of the plate-like body that is present outside the concaves of the die and has not been machined into ribs, and the flat punch is provided upstream in the conveying direction of the plate-like body of a final machining punch that forms the final rib. With the above construction, in an apparatus that is capable of forming a plurality of ribs in one closing operation of the upper mold and the lower mold, while a rib is being machined by the final machining punch and the final concave of the die, the part not machined into ribs is drawn in between the machining punch and the die without resistance. The flat punch starts to press and cause resistance to the part that has not been machined into ribs only after the formation of the final rib has been completed, and operates to flatten such part. This means that while a rib is being formed, the part that has not been machined into ribs is sufficiently drawn in between the machining punch and the die, which means it is possible to prevent thinning and snapping of the ribs. Also, even if ribs are successively machined by the respective machining punches, the plate-like body can be supplied and drawn in between the respective machining punches without resistance, which means it is possible to prevent thinning and snapping of the ribs. 
     The respective machining punches are shaped so that when a next machining punch enters a concave of the die to form a next rib, the machining punches do not contact the part of the plate-like body that has not been machined into ribs. 
     The respective machining punches are shaped so that when a next machining punch enters a concave of the die to form a next rib, the machining punches do not cause resistance even when the machining punches contact the part of the plate-like body that has not been machined into ribs. 
     According to the present invention, it is possible to prevent thinning and snapping of ribs that are formed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view depicting a punch and a die according to a first embodiment of a corrugated fin manufacturing apparatus according to the present invention; 
         FIGS. 2A to 2C  are diagrams useful in explaining the operation of the punch and a flat punch in the corrugated fin manufacturing apparatus depicted in  FIG. 1 ; 
         FIG. 3  is a side view of a second embodiment of a corrugated fin manufacturing apparatus according to the present invention; 
         FIG. 4  is a side view of the corrugated fin manufacturing apparatus depicted in  FIG. 3  when punches are successively lowered; 
         FIG. 5  is a side view depicting a state where all of the punches of the corrugated fin manufacturing apparatus depicted in  FIG. 3  have been lowered and the formation of ribs is complete; 
         FIG. 6  is a front view of the corrugated fin manufacturing apparatus depicted in  FIG. 3 ; 
         FIG. 7  is a front view depicting a state where all of the punches of the corrugated fin manufacturing apparatus depicted in  FIG. 6  have been lowered and the formation of ribs is complete; 
         FIG. 8  is a side view depicting the punches and die in the second embodiment; 
         FIGS. 9A to 9D  are diagrams useful in explaining the operation of the punches and flat punch in the second embodiment; 
         FIG. 10  is a diagram useful in explaining the shapes of the plurality of punches in the second embodiment; 
         FIG. 11  is a diagram useful in depicting a state where a pressing protrusion of a pressing cam block is pressing a pressed protrusion of a punch; 
         FIG. 12  is a diagram useful in depicting a state where the pressing protrusion of the pressing cam block is pressing the pressed protrusion of the punch; 
         FIG. 13  is a diagram useful in depicting a state where the pressing protrusion of the pressing cam block is pressing the pressed protrusion of the punch; 
         FIG. 14  is a diagram useful in depicting a state where the pressing protrusion of the pressing cam block is pressing the pressed protrusion of the punch; 
         FIG. 15  is a diagram useful in depicting the external form of a corrugated fin; and 
         FIG. 16  is a diagram useful in explaining the operation of a conventional corrugated fin manufacturing apparatus. 
     
    
    
     DESCRIPTION OF EMBODIMENT(S) 
     First Embodiment 
     Preferred embodiments of a corrugated fin manufacturing apparatus according to the present invention will now be described. 
       FIG. 1  depicts a punch provided on an upper mold part of the corrugated fin manufacturing apparatus and a die provided on a lower mold part when viewed from the side.  FIGS. 2A to 2C  are diagrams useful in explaining the operation of the punch depicted in  FIG. 1 . Note that a construction of a driving means and the like for the upper mold is omitted here. Note also that the corrugated fin manufacturing apparatus according to the present embodiment is an apparatus that forms one rib in one mold closing operation of the upper mold and the lower mold. 
     A die  36  is fixed to the upper surface of a table  35  of a lower mold  34  and has a plurality of concave and convexes corresponding to the form of the ribs  12  of the corrugated fin to be molded. As one example,  FIG. 1  depicts a state where two concaves and two convexes are formed. Out of the two concaves, a concave that is positioned downstream in the conveying direction A of a plate-like body  31  is a pilot concave  36   a  that is entered by a rib  12  that has already been formed to position the plate-like body  31 . Also, out of the two concaves, the concave positioned upstream in the conveying direction of the plate-like body  31  is a machining concave  36   b  that in combination with a machining punch  41  forms a rib. A lower-end convex  41   a  of a machining punch  41 , described later, enters the machining concave  36   b  to bend and machine the plate-like body  31 . 
     A wall surface on a downstream side in the conveying direction of the pilot concave  36   a  forms a convex  36   c  with a shape that protrudes upward and is capable of entering between the ribs  12 . The convex  36   c  enters a concave  40   d  on a downstream end surface of the pilot punch  40 , described later, and together with the pilot punch  40  holds a rib that has already been formed. The side surface on the upstream side in the conveying direction of the pilot concave  36   a  and the side surface on the downstream side in the conveying direction of the machining concave  36   b  form a convex  36   d  with a shape that protrudes upward and is capable of entering between the ribs  12 . The convex  36   d  enters between the pilot punch  40  and the machining punch  41 , described later. 
     On the die  36 , a mounting portion  37  for forming a part of the plate-like body  31  that has not been machined into ribs into a flat shape is provided upstream of the machining concave  36   b . In the present embodiment, the height of the mounting portion  37  is the same height as the height of the convexes  36   c ,  36   d  of the die  36 . This means that the part that has not been machined into ribs is formed at a position with the same height as the tops of peak parts of the ribs being formed. 
     The pilot punch  40  and the machining punch  41  are disposed above the die  36  along the conveying direction A of the plate-like body  31 . An upper mold  32  includes a base portion  54  disposed at an upper end of the upper mold  32  and a punch holder  56  that is disposed below the base portion  54  and slidably holds the respective punches. 
     At a lower end portion thereof, the pilot punch  40  has a convex  40   a  with a shape capable of entering the pilot concave  36   a . The convex  40   a  of the pilot punch  40  is disposed in substantially the center of the width of the pilot punch  40  in the conveying direction A of the plate-like body  31 . An end surface  40   c  on the downstream side of the pilot punch  40  in the conveying direction A is formed as a flat, perpendicular surface. Since the convex  40   a  is formed upstream of the end surface  40   c , the concave  40   d  is produced between the end surface  40   c  and the end surface on the downstream side of the convex  40   a  when looking from the side. When the upper mold and the lower mold are closed, the convex  36   c  of the die  36  described above enters into the concave  40   d . The pilot punch  40  is lowered before the machining punch  41  and a rib  12  that was previously formed is sandwiched by the pilot punch  40  and the pilot concave  36   a , thereby positioning the plate-like body  31 . 
     The machining punch  41  that is positioned upstream of the pilot punch  40  in the conveying direction A of the plate-like body  31  is provided so as to contact the plate-like body after the pilot punch  40 . On a lower end portion thereof, the machining punch  41  has a convex  41   a  with a shape capable of entering the machining concave  36   b . The plate-like body  31  that has been positioned by the pilot punch  40  and the pilot concave  36   a  is sandwiched between the convex  41   a  of the machining punch  41  and the machining concave  36   b  to form a rib  12 . In the present embodiment, an end surface  41   b  of the downstream side of the machining punch  41  includes the convex  41   a  and is formed as a substantially flat perpendicular surface. The end surface  41   b  contacts the upstream end surface of the pilot punch  40 , with such surfaces being able to slide over one another. 
     Together with an upstream-side end surface of the pilot punch  40 , the end surface  41   b  on the downstream side of the machining punch  41  forms a concave  41   d . The concave  41   d  is formed in a shape that is capable of being entered by the convex  36   d  of the die  36 , and when the upper mold and the lower mold are closed, the concave  41   d  and the convex  36   d  of the die  36  hold the upstream side of the peak of a rib that has already been formed. 
     Since the convex  41   a  of the machining punch  41  is formed so as to be biased toward the downstream side of the machining punch  41 , a concave  41   f  is formed between an upstream end surface of the convex  41   a  and an upstream end surface  41   e  of the machining punch  41 . An upper end portion of the concave  41   f  is formed at an upper position so as to not contact the part of the plate-like body  31  that has not been machined into ribs, even when the machining punch  41  has been lowered and entered inside the machining concave  36   b  to machine a rib. That is, in the present invention, the concave  41   f  on the upstream side of the convex  41   a  on the machining punch  41  is formed so as to extend higher than with the conventional art. 
     However, for the present invention, the upper end portion of the concave  41   f  is not limited to being formed at a position that is not contacted by the part that has not been machined into ribs. For example, provided that the plate-like body  31  can be smoothly drawn in without resistance even if the part that has not been machined into ribs is contacted, it will still be possible to prevent the ribs from thinning and snapping. In this case, if the part that has not been machined into ribs contacts the machining punch  41 , the part of the machining punch  41  that is contacted should be formed with a shape or with a surface form that takes the coefficient of friction of the surface into consideration so as to make the resistance against the plate-like body  31  extremely low. 
     Energizing means  44  such as springs for downwardly energizing the pilot punch  40  and the machining punch  41  are respectively provided for the punches  40  and  41 . Upper end portions of the energizing means  44  are connected to the base portion  54 . However, the energizing means  44  is not limited to being provided above the respective punches  40 ,  41 . 
     A flat punch  43  for acting in combination with the mounting portion  37  of the die  36  to sandwich and flatten the part of the plate-like body  31  that has not been machined into ribs is disposed on an upstream side of the machining punch  41  in the conveying direction A of the plate-like body  31 . Note that in the embodiment depicted in  FIGS. 1 and 2 , the energizing means  44  for energizing the flat punch  43  downward is provided at an upper end portion of the flat punch  43  and the upper end portion of the energizing means  44  is connected to the base portion  54 . However, the flat punch  43  may be attached directly to the base portion  54  with no energizing means  44  in between. A lower surface  43   a  of the flat punch  43  is formed so as to be parallel to the mounting portion  37  of the die  36  so that the plate-like body  31  that is sandwiched between the flat punch  43  and the mounting portion  37  is flattened. 
     The flat punch  43  in the present embodiment is formed in a substantially cubic shape and an end surface on the downstream side of the flat punch  43  slidably contacts the upstream end surface  41   e  of the machining punch  41 . The position of the lower surface  43   a  of the flat punch  43  is set so as to not contact the part of the plate-like body  31  that has not been machined into ribs while a rib is being formed by the convex  41   a  of the machining punch  41  and the machining concave  36   b  of the die  36 . After the formation of a rib is complete, the flat punch  43  starts moving toward the mounting portion  37  of the die  36 . The flat punch  43  that has started moving presses the part of the plate-like body  31  that has not been machined into ribs downward and presses the unmachined part of the plate-like body  31  in combination with the mounting portion  37  so as to flatten the unmachined part. 
     Next, the operation of the respective punches and the flat punch will be described with reference to  FIGS. 2A to 2C . 
     As depicted in  FIG. 2A , first, the pilot punch  40  is lowered and enters a rib  12  that has already been formed to position the plate-like body  31 . After this, the machining punch  41  is lowered and the plate-like body  31  is sandwiched between the machining punch  41  and the machining concave  36   b  to form a rib. While a rib is being formed, both the flat punch  43  and the machining punch  41  have positions and shapes that do not contact the part of the plate-like body  31  that has not been machined into ribs. Since the part that has not been machined into ribs is not contacted at any position during the formation of the ribs, the drawing-in of the plate-like body  31  between the machining punch  41  and the machining concave  36   b  of the die  36  that accompanies the formation of a rib can occur without resistance to movement of the plate-like body  31 . Accordingly, it is possible to mold ribs that have sufficient thickness. 
     The flat punch  43  is provided so that operation thereof starts after the formation of a rib  12  by the machining punch  41  has been completed. Before operation starts, the flat punch  43  is disposed at a position that does not contact the part of the plate-like body  31  that has not been machined into ribs. More specifically, the lower surface  43   a  of the flat punch  43  is provided at a position that is higher than a highest position  31   h  of the plate-like body  31  that can be imagined in a case where the plate-like body  31  is bent. 
     As depicted in  FIG. 2B , when the machining punch  41  has completed the formation of a rib  12 , the flat punch  43  starts to be lowered. When the flat punch  43  is lowered, the lower surface  43   a  of the flat punch  43  contacts the highest position  31   h  of the plate-like body  31 . After this, the flat punch  43  progressively presses down the upwardly bent part of the plate-like body  31  that has not been machined into ribs. 
     Here, even if the flat punch  43  presses down the part of the plate-like body  31  that has not been machined into ribs, since the molding of a rib has already been completed, there will be no further drawing in of the plate-like body  31  that accompanies the molding of a rib. 
       FIG. 2C  depicts the bottom dead center of the upper mold  32 . At this point, the part of the plate-like body  31  that has not been machined into ribs is sandwiched between the flat punch  43  and the mounting portion  37  of the die  36  so that the unmachined part of the plate-like body  31  is pressed so as to become flattened. 
     Note that for the operation of the flat punch  43  to start after the formation of a rib  12  by the machining punch  41  has been completed, the length of the flat punch  43  should be shorter than the length of the machining punch  41  as depicted in  FIGS. 1 and 2 , or alternatively when the length of the flat punch  43  is equal to the length of the machining punch  41 , a position where the upper end portion of the flat punch  43  is attached to the base portion  54  should be provided higher than a position where the machining punch  41  is attached to the base portion  54 . The position of the upper end portion of the flat punch  43  is positioned relative to the base portion  54  so that when the lower end portion of the convex  41   a  of the machining punch  41  has contacted an inner bottom surface of the machining concave  36   b  of the die  36 , the base portion  54  presses the upper end portion of the flat punch  43  so as to cause machining by the flat punch  43 . 
     However, the present invention is not limited to the flat punch  43  being disposed at a position that does not contact the part that has not been machined into ribs. 
     For example, provided that the plate-like body  31  is smoothly drawn in without resistance even if the part that has not been machined into ribs is contacted, it will still be possible to prevent thinning and snapping of the ribs. In this case, even if the part that has not been machined into ribs contacts the flat punch  43 , the contacting part of the flat punch  43  should be formed with a shape or with a surface form that takes the coefficient of friction of the surface into consideration so as to make the resistance against the plate-like body  31  extremely low. 
     Second Embodiment 
     Although the embodiment described above is a corrugated fin manufacturing apparatus that forms a single rib in a single mold closing operation of the upper mold and the lower mold, the second embodiment described below is a corrugated fin manufacturing apparatus that is capable of forming a plurality of ribs in a single mold closing operation of the upper mold and the lower mold. Note that in some cases, the component elements that are the same as in the embodiment described above have been assigned the same reference numerals and description thereof is omitted. 
       FIG. 3  is a side view depicting the overall construction of a corrugated fin manufacturing apparatus, and  FIGS. 4 and 5  depict a state where the punch depicted in  FIG. 3  has been driven.  FIGS. 6 and 7  depict the states in  FIGS. 3 to 5  from the front. The corrugated fin manufacturing apparatus  30  (hereinafter sometimes referred to simply as the “manufacturing apparatus”) is an apparatus that molds a corrugated fin  10  in which a plurality of ribs  12  are formed by using a press to bend and machine a thin plate-like body  31  that is made of metal such as copper or aluminum. 
     The manufacturing apparatus  30  includes the lower mold  34  and the upper mold  32  that is provided so as to be capable of moving toward and away from the lower mold  34 . The lower mold  34  includes the die  36  that is fixed above the table  35 , the pilot punch  40 , a plurality of machining punches  41 ,  41  . . . , the flat punch  43 , and two pressing cam blocks  42  disposed above the plurality of machining punches  41 ,  41 , . . . . The upper mold  32  includes cam plates  39  that move up and down and a driving means, not depicted. The driving means drives the cam plates  39  in the up-down direction and as one example, a hydraulic cylinder or the like that drives the cam plates  39  in the up-down direction is used. 
     The construction of the lower mold and the upper mold will now be described with reference to  FIG. 8 . First, the construction of the lower mold  34  will be described in detail. 
     The die  36  is fixed to the upper surface of the table  35  and has a plurality of convexes and concaves in accordance with the shapes of the ribs of the corrugated fin to be molded.  FIG. 8  depicts a state where as one example, four concaves and four convexes are formed. The convexes  41   a  at the lower ends of the punches  41 , described later, enter inside the concaves of the die  36  to bend and machine the plate-like body, with the convexes of the die  36  mold peak parts of the ribs  12 . 
     The plurality of concaves of the die  36  are formed along the conveying direction A of the plate-like body  31 . Out of the plurality of concaves, a concave  36   a  that is present furthest downstream in the conveying direction of the plate-like body  31  is a pilot concave  36   a  for allowing a rib  12  that has already been formed to be inserted to position the plate-like body  31 . Also, out of the plurality of concaves, the concaves aside from the pilot concave  36   a  are machining concaves  36   b  which act together with the machining punches  41  to form the ribs. The convexes  41   a  at the lower ends of the respective machining punches  41 , described later, successively enter the machining concaves  36   b  from the downstream side to the upstream side in the conveying direction of the plate-like body  31  to bend and machine the plate-like body  31  and thereby successively form a plurality of ribs. 
     A wall surface on the downstream side of the pilot concave  36   a  in the conveying direction forms the convex  36   c  with a shape that protrudes upward and is capable of entering between the ribs  12 . The convex  36   c  enters the concave  40   d  on a downstream end surface of the pilot punch  40 , described later, and together with the pilot punch  40  holds a rib that has already been formed. Out of the plurality of convexes of the die  36 , convexes  36   d  aside from the convex  36   c  that is positioned furthest downstream in the conveying direction are inserted between the respective machining punches  41 , described later. 
     Here, a mounting portion  37  for flattening a part of the plate-like body  31  that has not been machined into ribs is provided on the die  36  upstream of a final machining concave  36   b  that forms a final rib that is to be formed last. In the present embodiment, the height of the mounting portion  37  is equal to the height of the convexes  36   c ,  36   d  of the die  36 . This means that the part that is not machined into ribs is flattened at a position with the same height as the tops of peak parts of the ribs being formed. 
     A plurality of punches are disposed along the conveying direction A of the plate-like body  31  above the die  36 . Out of the plurality of punches, the punch that is furthest downstream in the conveying direction A of the plate-like body  31  is the pilot punch  40 . At a lower end portion thereof, the pilot punch  40  has the convex  40   a  with a shape capable of entering the pilot concave  36   a . The convex  40   a  of the pilot punch  40  is disposed in substantially the center in the width of the pilot punch  40  in the conveying direction A of the plate-like body  31 . The end surface  40   c  on the downstream side in the conveying direction A of the pilot punch  40  is formed as a flat, perpendicular surface. Since the convex  40   a  is formed upstream of the end surface  40   c , the concave  40   d  is produced between the end surface  40   c  and the end surface on the downstream side of the convex  40   a  when looking from the side. When the upper mold and the lower mold are closed, the convex  36   c  of the die  36  described above enters into the concave  40   d . The pilot punch  40  is lowered before the machining punches  41  and a rib  12  that has been previously formed is sandwiched by the pilot punch  40  and the pilot concave  36   a , thereby positioning the plate-like body  31 . 
     A plurality of machining punches  41  are disposed upstream of the pilot punch  40  in the conveying direction A of the plate-like body  31  and are provided so as to be successively lowered from the downstream side to the upstream side in the conveying direction to bend and machine the plate-like body  31 . On a respective lower end portion thereof, each machining punch  41  has a convex  41   a  with a shape capable of entering one of the machining concaves  36   b . The plate-like body  31  that has been positioned by the pilot punch  40  and the pilot concave  36   a  is successively sandwiched between the convexes  41   a  of the machining punches  41  and the machining concaves  36   b  to successively form a plurality of ribs  12 . 
     The convexes  41   a  of the machining punches  41  are formed so as to be biased toward the downstream side. This means that on each machining punch  41 , a concave  41   f  is formed between an upstream end surface of the convex  41   a  and an upstream end surface  41   e  of a main part of the machining punch  41 . The upper end portion of the concave  41   f  is formed at an upper position so as to not contact the part of the plate-like body  31  that has not been machined into ribs, even while a next rib is being machined by a next machining punch  41  entering the corresponding machining concave  36   b  after a present rib has been machined by the present machining punch  41  entering the corresponding machining concave  36   b . That is, in the present embodiment, the concave  41   f  on the upstream side of the convex  41   a  on a machining punch  41  is formed so as to extend higher than with the conventional art. By doing so, during the machining of ribs, the machining punches  41  do not cause resistance to the drawing in of the plate-like body  31 . 
     However, for the present invention, the upper end portion of the concave  41   f  is not limited to being formed at a position that is not contacted by the part that has not been machined into ribs. 
     For example, in the same way as the embodiment described above, provided that the plate-like body  31  can be smoothly drawn in without resistance even if the part that has not been machined into ribs is contacted, it will still be possible to prevent the ribs from thinning and snapping. In this case, if the part unmachined into ribs contacts the machining punches  41 , the parts of the machining punches  41  that are contacted should be formed with a shape or with a surface form that takes into consideration the coefficient of friction of the surface so as to make the resistance against the plate-like body  31  extremely low. 
     The flat punch  43  for acting in combination with the mounting portion  37  of the die  36  to sandwich and flatten the part of the plate-like body  31  that has not been machined into ribs is disposed on an upstream side in the conveying direction A of the plate-like body  31  of a final machining punch  41  that is positioned furthest upstream in the conveying direction A of the plate-like body  31  out of the plurality of machining punches  41 . The lower surface  43   a  of the flat punch  43  is formed so as to be parallel to the mounting portion  37  of the die  36  so that the plate-like body  31  that is sandwiched between the flat punch  43  and the mounting portion  37  is flattened. 
     The flat punch  43  in the present embodiment is formed in a substantially cubic shape and an end surface on the downstream side of the flat punch  43  slidably contacts the upstream end surface  41   e  of the final machining punch  41 . The position of the lower surface  43   a  of the flat punch  43  is set so as to not contact the part of the plate-like body  31  that has not been machined into ribs while a rib is being formed by the final machining punch  41  and the corresponding machining concave  36   b  of the die  36 . After the formation of ribs is complete, the flat punch  43  starts moving toward the mounting portion  37  of the die  36 . The flat punch  43  that has started moving presses the part of the plate-like body  31  that has not been machined into ribs downward and presses the unmachined part of the plate-like body  31  in combination with the mounting portion  37  so as to flatten the unmachined part. 
     However, the present invention is not limited to the flat punch  43  being disposed at a position that does not contact the part that has not been machined into ribs. 
     For example, provided that the plate-like body  31  is smoothly drawn in without resistance even if the part that has not been machined into ribs is contacted, it will still be possible to prevent the ribs from becoming thin and snapping. In this case, even if the part that has not been machined into ribs contacts the flat punch  43 , the contacting part of the flat punch  43  should be formed with a shape or with a surface form that takes the coefficient of friction of the surface into consideration so as to make the resistance against the plate-like body  31  extremely low. 
     Note that although energizing means such as springs are respectively provided above the pilot punch  40 , the machining punches  41 , and the flat punch  43  to energize such components, such energizing means are omitted from  FIGS. 8 and 9 . Such energizing means are provided between attachment portions  45  of the punch  40  and punch supporting portions  38  provided on the table  35  as depicted in  FIGS. 6 and 7 . 
     The operation of the punches and the flat punch will now be described based on  FIGS. 9A to 9D . As depicted in  FIG. 9A , the pilot punch  40  is lowered first and enters a rib  12  that has already been formed by a previous mold closing operation to position the plate-like body  31 . Next, as depicted in  FIG. 9B , the plurality of machining punches  41  are successively lowered from the downstream side in the conveying direction to successively form ribs. The flat punch  43  is provided so as to start operation following the completion of formation of the final rib  12  by the final machining punch  41 . Before the operation starts, the flat punch  43  is disposed at a position so as to not contact the part of the plate-like body  31  that has not been machined into ribs. More specifically, the lower surface  43   a  of the flat punch  43  is provided at a position that is higher than a highest position  31   h  of the plate-like body  31  that can be imagined in a case where the plate-like body  31  is bent. 
     During the formation of the final rib  12  or ribs  12  aside from the final rib, the flat punch  43  is not lowered, and the flat punch  43  operates so as to be lowered following the completion of the formation of the final rib  12 . Since the part that has not been machined into ribs is not contacted at any position during the formation of the ribs, the drawing-in of the plate-like body  31  between the machining punch  41  and the die  36  that accompanies the formation of ribs can occur without resistance to movement of the plate-like body  31 . Accordingly, it is possible to mold ribs that have sufficient thickness. 
     As depicted in  FIG. 9C , when the formation of the final rib  12  by the final machining punch  41  has been completed, the flat punch  43  is lowered. When the flat punch  43  is lowered, the lower surface  43   a  of the flat punch  43  contacts the highest position  31   h  of the plate-like body  31 . After this, the flat punch  43  progressively presses down the upwardly bent part of the plate-like body  31  that has not been machined into ribs. 
     Here, even if the part of the plate-like body  31  that has not been machined into ribs is pressed down by the flat punch  43 , since the molding of all of the ribs has already been completed, there will be no further drawing in of the plate-like body  31  that accompanies the molding of ribs. 
       FIG. 9D  depicts the bottom dead center of the upper mold  32 . At this point, the part of the plate-like body  31  that has not been machined into ribs is sandwiched between the flat punch  43  and the mounting portion  37  of the die  36  so that the unmachined part of the plate-like body  31  is pressed so as to become flattened. 
     Next, the construction for successively lowering a plurality of punches in a single mold closing operation will be described in detail with reference to  FIGS. 6 ,  7 , and  10 . The punches  40 ,  41 , and  43  (the pilot punch, the machining punches, and the flat punch) are formed across a wide width along a direction (hereinafter referred to as a width direction of a punch) C that is perpendicular to the conveying direction A of the plate-like body  31 . 
     Both end portions of the punches  40 ,  41 ,  43  in the width direction C are formed as the attaching portions  45  for attaching to the table  35  of the lower mold  34  and are attached via the energizing means  44  that energize the punches upward from the punch support portions  38  provided on the table  35 . In the present embodiment, a plurality of springs that are capable of being compressed in the up-down direction are used as the energizing means  44 . However, such examples of the energizing means  44  are not limited to being provided at such positions. 
     Pressed protrusions  46 , which are contacted by pressing protrusions  49  formed on lower surfaces of the pressing cam blocks  42  for driving the punches  40 ,  41 , and  43 , are formed on the upper surfaces of the punches  40 ,  41 , and  43 . Side walls  47  of the pressed protrusions  46  are formed so as to be tapered which makes it easy for the pressing protrusions  49  to ride upward. In the example in the present embodiment, the pressed protrusions  46  are formed at four positions along the width direction C on each of the punches  40 ,  41 , and  43 . 
     The punches  40 ,  41 , and  43  are formed so that the widths of the upper surfaces of the pressed protrusions  46  thereof become wider in the order in which the bending and machining of the plate-like body  31  is carried out (see  FIG. 10 : note however that in  FIG. 10 , the number of punches and the lower end portions thereof are omitted). 
     In the present embodiment, ribs are successively formed in the direction of the arrow B in  FIG. 4  from the downstream side in the conveying direction A of the plate-like body  31 . For this reason, the upper surfaces of the pressed protrusions  46  of the pilot punch  40  positioned furthest downstream in the conveying direction A of the plate-like body  31  are the widest and the upper surfaces of the pressed protrusions  46  of the punches  40 ,  41 , and  43  are formed so as to narrow toward the upstream side in the conveying direction A. More specifically, the upper surfaces of the pressed protrusions  46  formed on the upper surface of the flat punch  43  are the narrowest out of the plurality of punches. 
     As depicted in  FIGS. 6 and 7 , out of the plurality of punches,  40 ,  41 , and  43  (in the present embodiment, eight punches), the tapered side walls  47  of the pressed protrusions  46  on the pilot punch  40  that is lowered first toward the die  36  are formed at the closest positions (the positions a 1 ) to the pressing protrusions  49  of the pressing cam blocks  42 , and the tapered side walls  47  of the pressed protrusions  46  on the next punch to be lowered toward the die  36  are formed at the next closest position (the position a 2 ) to the pressing protrusions  49  of the pressing cam blocks  42 . 
     The positions of the tapered side walls  47  of the plurality of punches,  40 ,  41 , and  43  become gradually further from the pressing protrusions  49  of the pressing cam blocks  42  in the order in which the punches are lowered toward the die  36 , and the tapered side walls  47  of the pressed protrusions  46  on the flat punch  43  that is lowered toward the die  36  last, are formed at positions (the positions a 8 ) that are furthest from the pressing protrusions  49  of the pressing cam blocks  42 . Note that since the flat punch  43  is provided to start operating after the formation of the final rib  12  has been completed by the final machining punch  41 , the formation positions of the side walls  47  of the pressed protrusions  46  of the flat punch  43  are formed at positions that cause the flat punch  43  to operate after the final machining punch  41  has been completely lowered. 
     The pressing cam blocks  42  are disposed above the punches  40 ,  41 , and  43  at positions that constantly contact the upper surfaces of the plurality of punches  40 ,  41 , and  43 . That is, when the upper mold  32  and the lower mold  34  are open, the pressing protrusions  49  of the pressing cam blocks  42  contact positions aside from the pressed protrusions  46 , and when the mold is being closed, the pressing protrusions  49  contact the pressed protrusions  46  of at least one of the punches  40 ,  41 , and  43 . Two pressing cam blocks  42  are provided with the center in the width direction C of the punches  40 ,  41 , and  43  as a boundary between the pressing cam blocks  42  and are capable of moving along the width direction C of the punches  40 ,  41 , and  43 . The movement of the pressing cam blocks  42  is restricted by the operation of the cam plates  39  of the upper mold  32 , described later. 
     In the present embodiment, when the upper mold  32  and the lower mold  34  are open, the two pressing cam blocks  42 ,  42 , are positioned in substantially the center in the width direction C of the punches  40 ,  41 , and  43  (the state in  FIG. 6 ), and when the upper mold  32  and the lower mold  34  are closed, the two pressing cam blocks  42 ,  42  move along the width direction C of the punches  40 ,  41 , and  43  so us to move apart from one another (the state in  FIG. 7 ). 
     The pressing protrusions  49  that protrude downward are formed at two positions on lower surfaces of each of the pressing cam blocks  42 ,  42 . The pressing protrusions  49  are formed in an inverse taper so as to become gradually narrower toward the bottom, and when the upper mold  32  and the lower mold  34  are open, are at positions that do not contact the pressed protrusions  46  on the upper surfaces of the punches  40 ,  41 , and  43  (the state in  FIG. 6 ). When the upper mold  32  and the lower mold  34  are closed, the pressing cam blocks  42 ,  42  move in the width direction C of the punches  40 ,  41 , and  43  and the pressing protrusions  49  ride up the tapered side walls  47  of the widest of the pressed protrusions  46  out of the punches  40 ,  41 , and  43  so that the punches  40 ,  41 , and  43  are pressed down in order against the energizing force of the energizing means  44  starting with the punch with the widest pressed protrusions  46  (the state in  FIG. 7 ). 
     Cain channels  52  in which bearings  50  provided on the respective pressing cam blocks  42  are housed are formed in the cam plates  39  of the upper mold  32 . 
     Each cam channel  52  is formed in a suitable shape so as to move the pressing cam blocks  42  in the width direction C of the punches  40 ,  41 , and  43  as the cam plates  39  are lowered. That is, the cam channels  52  are formed so as to be inclined so that the bearings  50  gradually move in the width direction C of the punches  40 ,  41 , and  43 . More specifically, the cam channels  52  provided so as to move the pressing cam block  42  that is positioned on the right out of the pressing cam blocks  42  depicted in  FIG. 6  in the direction of the arrow D are formed diagonally upward to the right, and the cam channels  52  provided so as to move the pressing cam block  42  that is positioned on the left in the direction of the arrow E are formed diagonally upward to the left. 
     A method of manufacturing a corrugated fin is described below based on the overall operation of the manufacturing apparatus  30 . 
     When the upper mold  32  and the lower mold  34  are opened, a conveying apparatus, not depicted, conveys the plate-like body  31  between the die  36  and the punches  40 ,  41 , and  43 . After this, a mold closing operation is started, and when the upper mold  32  is lowered toward the lower mold  34 , the cam plates  39  are also lowered. The bearings  50  of the pressing cam blocks  42  are lowered along the cam channels  52  of the cam plates  39  and the pressing cam blocks  42  move in the horizontal direction. 
     The two pressing cam blocks  42  are respectively moved by the cam plates  39  in the horizontal direction so as to move apart (in the directions of the arrow D and the arrow E in  FIG. 6 ). The pressing protrusions  49  provided on the respective lower surfaces of the pressing cam blocks  42  are pressed down toward the pilot punch  40  so as to ride up onto the upper surfaces of the pressed protrusions  46  of the pilot punch  40  which is the first to be lowered out of the plurality of punches,  40 ,  41 , and  43  (see  FIGS. 11 to 14 ). 
     By further moving the pressing cam blocks  42  in the horizontal direction, the punches  40 ,  41 , and  43  are successively pressed downward in order of the width of the upper surfaces of the pressed protrusions  46  of the punches  40 ,  41 , and  43  (i.e., in the order in which the positions of the tapered side walls  47  that rise up the pressed protrusions  46  are close to the center in the width direction C of the punches  40 ,  41 , and  43 ). In combination with the die  36 , the lowered machining punches  41  bend and machine the plate-like body  31 . Since the plurality of machining punches  41  are successively lowered from the front in the conveying direction A of the plate-like body  31 , ribs are successively formed in the plate-like body  31 . 
     When the upper mold  32  is positioned at the bottom dead center, the pressing protrusions  49  of the pressing cam blocks  42  are positioned on the upper surfaces of the pressed protrusions  46  of the flat punch  43  that is lowered last out of the plurality of punches  40 ,  41 , and  43 . At this position, all of the punches  40 ,  41 , and  43  have been lowered, the formation of all of the ribs by the punches  40 ,  41 , and  43  and the die  36  is complete, and the part where ribs have not been machined is formed so as to be flat. After this, the driving means is driven to start the raising of the upper mold  32 . Due to the raising of the upper mold  32 , the cam plates  39  are also raised, which results in the bearings  50  of the pressing cam blocks  42  gradually moving along the cam channels  52  so as to gradually move toward the center in the width direction C of the punches  40 ,  41 , and  43 . 
     By doing so, the pressing protrusions  49  of the two pressing cam blocks  42  become successively separated from the upper surface of the pressed protrusions  46  of the punches  40 ,  41 , and  43  that were pressed downward. That is, pressing by the pressing cam blocks  42  is released in the order in which the width of the pressed protrusions  46  in the width direction is narrow, and the punches for which the pressing of the pressing cam blocks  42  is released move upward in order due to the energizing force of the energizing means  44 . The plurality of punches  40 ,  41 , and  43  are raised in the opposite order to the order in which the punches were lowered, and when the pressing protrusions  49  of the pressing cam blocks  42  become separated from the pressed protrusions  46  of all of the punches  40 ,  41 , and  43 , the upper mold  32  reaches the top dead center, thereby completing one mold closing operation of the upper mold  32  and the lower mold  34 . 
     After this, by using a conveying means, not depicted, the plate-like body  31  in which the ribs have been formed is conveyed from the manufacturing apparatus  30  to outside the apparatus to complete the manufacturing of a corrugated fin. 
     Note that although the upper surface of the flat punch  43  is constructed in this second embodiment so that the pressed protrusions  46  are formed in the same way as on the machining punches  41  and the pilot punch  40 , with such pressed protrusions  46  being pressed to lower the flat punch  43 , the upper surface may be composed of a base portion  54  and a punch holder  56  in the same way as in the first embodiment. 
     Note that in the second embodiment, a construction including rotating bodies may be used as the pressing protrusions of the pressing cam blocks. As such rotating bodies, it is possible to use cylindrical rollers that extend along the conveying direction A of the plate-like body  31  or spherical rollers. 
     In addition, the two pressing cam blocks described above are positioned so as to be centered in the width direction of the punches when the mold is open and move so as to become apart when the mold is closed. However, the movement of the two pressing cam blocks is not limited to movement in such direction. That is, it is also possible to use a construction where the two pressing cam blocks are positioned at both ends in the width direction of the punches when the mold is open and the pressing cam blocks move so as to approach one another when the mold is closed and thereby successively lower the respective punches. 
     Although various preferred embodiments of the present invention have been described above, it should be obvious that the present invention is not limited to such embodiments and can be subjected to a variety of modifications within a range that does not depart from the spirit of the invention.