Abstract:
A punching unit for punching holes of a selected geometry in a wall of a component. The punching unit has a frame for supporting the component and the tool and die assembly releaseably securable to the frame. Tool and die assembly has a punch operatively coupled to a mandrel and a male die member and a female die member cooperating to form the hole in the wall. A portion of the tool and die assembly is interchangeable to provide a selected one of a plurality of predetermined hole geometries for the component.

Description:
[0001]    The present invention relates to an apparatus for producing punched apertures in a wall of a component.  
         BACKGROUND OF THE INVENTION  
         [0002]    Punching a hole in an exterior wall of a tubular member is practiced in many areas of industry. The location and size of the holes facilitate access either through or into the interior of the tubular member, at positions other than the ends of the tube. The punching of holes through sheet metal portions also facilitate access from one side of the sheet to the other. Commercially available punching units are used to manufacture these holes, due to their repeatability of position and orientation of the holes. Drills are another device that can be used to create these holes, but the drills can create complications due to a formation of burrs at an edge of the hole, a formation of chips, and a potential need for a lubricant. In addition, the drills are typically slower for hole formation than the punching units, which also have an added benefit of being able to produce hole shapes other than circular.  
           [0003]    One example of a punching unit is taught by U.S. Pat. No. 3,848,497. This patent teaches a mandrel attached to a frame, by means of a fastener in the interior of the unit. A tube to be punched is slid over the mandrel, above which lies a punch. The punch includes a female die member and the mandrel includes a male die member. One disadvantage of this unit is that setup time for the female and male die members can be lengthy, due to the number of fasteners and adjustments used to assemble the unit. Accordingly, the punching unit of the &#39;497 patent is not readily adaptable to produce a variety of different sized or shaped holes, without incurring substantial down-time to change the members that correspond to a desired hole geometry. Therefore, it is common for a manufacturer to have a series of punching units, one for each hole geometry to be produced. This arrangement can reduce down-time, but requires the manufacturer to purchase multiple punching units.  
           [0004]    Another punching unit is taught by U.S. Pat. No. 4,744,276, which discloses a punch assembly for producing a series of holes along a length of the tubular member. The tubular member is fed progressively over the mandrel, so that a punch head can be operated cyclically in order to punch a series of holes in the tube. Unfortunately, the punching unit of the &#39;276 patent also suffers from the same adaptability problem as the &#39;497 patent. Furthermore, the mandrel of the &#39;276 patent is replaced as a single unit when it is worn out, which is undesirable. Mandrels are typically precision made to close tolerances and can be expensive to replace.  
           [0005]    It is in object of the present invention to obviate or mitigate some of the above presented disadvantages by providing an adaptable punching unit.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the present invention there is provided an apparatus for punching an aperture of selected geometry in a wall of a component. The apparatus comprises a frame for supporting the component and a tool and die assembly releaseably securable to the frame. The tool and die assembly has a punch operatively coupled to a mandrel and comprises a male die member and female die member cooperating to form the aperture in the wall. At least a portion of the tool and die assembly is interchangeable to provide a selected one of a plurality of predetermined aperture geometries. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    These and other features of the preferred embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:  
         [0008]    [0008]FIG. 1 is a perspective exploded view of a tube punching unit;  
         [0009]    [0009]FIG. 2 is a side view of an assembled tube punching unit of FIG. 1;  
         [0010]    [0010]FIG. 3 is an end view of the unit of FIG. 1;  
         [0011]    [0011]FIG. 4 is a side view of further embodiment of the unit of FIG. 1;  
         [0012]    [0012]FIG. 5 is a perspective view of a further embodiment of a mandrel of FIG. 1; and  
         [0013]    [0013]FIG. 6 is a side view of the mandrel of FIG. 5. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    Referring to FIG. 1, a punching unit  10  consists of a punch support  12  connected to a base  14 . Situated between the base  14  is a mandrel support  16 . A tool and die assembly  17  consists of a mandrel  18   a,b  and a punch  22   a,b . The mandrel  18   a,b  is received by a mandrel bore  20  of the support  16  and secured therein. The punch  22   a,b  is received by a punch bore  24  in a guide assembly  58  and a bore  25  in the support  12 , and is retained therein by a punch retaining pin  26 . Once assembled, as shown in FIG. 2, a male die member  28   a  or  28   b , located on the punch  22   a,b,  is aligned vertically with a corresponding female die member  30   a  or  30   b , located in the mandrel  18   a,b . A tubular member  32  is then positioned on a correspondingly dimensioned shaft  34  of the mandrel  18   a,b . A punch head  36  is then displaced along a vertical axis  56 , either manually or by means of an actuator (not shown), causing the male die member  28   a,b  to pass through an exterior wall of the tube  32  and enter the corresponding female die member  30   a,b,  thereby producing a hole or aperture  38  in the member  32 . A support block  19  provides support for potential bending stresses placed on the mandrel  18   a,b  as the punch  22   a,b  impacts the member  32 . The member  32  is positioned in a channel  21  and rests on the block  19 , as the member  32  is positioned on the mandrel  18   a,b.    
         [0015]    As can be seen in FIGS. 1 and 2, the mandrel  18   a,b  is retained in the bore  20  by a retaining screw  40 . The screw  40  is received by bore  42 , located on a rear face  44  of the mandrel support  16 . The mandrel  18  has a threaded bore  46  that is alignable with the bore  42 . The retaining screw  40  has a corresponding male threaded member  48 , which is threaded into the threaded bore  46  to fasten the mandrel  18  to the mandrel support  16 . A key-way  50  passing through the mandrel support  16  is aligned with a cutout  52  in the mandrel  18 , when the mandrel  18  is received by the bore  20 . A key  54  is received by the key-way  50  and along the aligned cutout  52 , thereby facilitating alignment of the female die member  30   a,b  along the vertical axis  56  of the punch  22 .  
         [0016]    The punch  22   a,b  is received by the bores  24 ,  25  and retained therein by a punch retaining pin  26 , located on the guide assembly  58 . The guide assembly  58  consists of a guide head  60 , a stripping spring  62 , a guide portion  64 , and a lifter spring  66 . The guide assembly  58  permits the punch  22   a,b  to be displaced in a reciprocal fashion along the axis  56 . The springs  62  and  66  bias the male die member  28   a,b  upwardly away from the female die member  30   a,b . The guide portion  64  inhibits the punch  22   a,b  from deviating away from the vertical axis  56  during operation of the punch unit  10 .  
         [0017]    The punch  22   a,b  has an elongated cutout  68 . A distal end (not shown) of the retaining pin  26  is engaged towards the cutout  68  and is situated adjacent to a flat portion  70  of the cutout  68 , as the punch  22   a,b  reciprocates along the axis  56 . The distal end of the pin  26  may contact the portion  70 , if desired. The function of the retaining pin  26  and cutout  68  arrangement is to facilitate displacement of the punch  22   a,b  in the bores  24 ,  25 , while at the same time inhibiting accidental removal of the punch  22   a,b  from the bores  24 ,  25  when the pin  26  is engaged.  
         [0018]    In operation of the punch unit  10  the appropriate mandrel  18   a  or  18   b  is selected (with the corresponding female die member  30   a,b ) and is received by the bore  20 . The angular orientation of the mandrel  18   a,b  is adjusted until the cutout  52  is aligned with the key-way  50 . The key  54  is then inserted into the key-way  50  so that a bottom surface  74  of the key  54  rests against a corresponding top surface  76  of the cut-out  52 , thereby fixing the angular orientation of the mandrel  18   a,b  in the bore  20 . This arrangement helps to align the female die member  30   a,b  along the vertical axis  56 . The retaining screw  40  is then received by the bore  42 , and the male threaded member  48  is screwed into the corresponding threaded bore  46  of the mandrel  18   a,b,  thereby securely fastening the mandrel  18   a,b  to the mandrel support  16 .  
         [0019]    The punch retaining pin  26  is then retracted out of the bore  24 , in order to allow the punch  22   a,b  to be inserted therein until the punch head  36  contacts the guide head  60 . The face  70  is aligned parallel with the distal end of the pin  26  and then the pin  26  is engaged towards the punch  22   a,b,  thereby retaining the punch  22   a,b  in the bores  24 ,  25 . A correspondingly sized tubular member  32  is positioned on the shaft  34  of the mandrel  18   a,b  and held in position (either manually or with the aid of clamps), as the punch head  36  is displaced with sufficient force towards the punch support  12 . This displacement causes the male die member  28   a,b  to be driven through the exterior wall of the tubular member  32  and into the female die member  30   a,b,  thereby cutting out a portion  78  of the wall to produce the hole  38 . It should be noted that a passageway  72  can be situated in the base  14  along the axis  56 . The passageway  72  can receive the blanks  78  as they are cut out of the tubular member  32  by the punch  22   a,b,  thereby facilitating their removal from the punch unit  10 .  
         [0020]    When an operator of the punch unit  10  wishes to produce a hole of different geometry, the retaining pin  26  is retracted from the bore  24  and the punch  22   a,b  is removed therefrom. A different punch  22   a,b  is selected, inserted into the bores  24 ,  25 , and the pin  26  is engaged towards the punch  22   a,b . In regards to the mandrel  18   a,b,  the retaining screw  40  is removed from the bore  42  and the key  54  is removed from the key-way  50 , thereby permitting the mandrel  18   a,b  to be removed from the bore  20 . At this stage, an appropriate mandrel  18   a,b  corresponding to the selected punch  22   a,b  is received by the bore  20  and secured therein by the retaining screw  40  and key  54 . The punch unit  10  is now ready for use by the operator to produce holes  38  with the selected hole geometry, as described above.  
         [0021]    It should be noted that the punch unit  10  of the present invention is adaptable for a wide variety of differently configured holes  38 , due to the interchangeability of the punch  22   a,b  and corresponding mandrel  18   a,b . Connections of the punch  22   a,b  to the punch support  12 , and the mandrel  18   a,b  to the mandrel support  16 , are simplified by use of the retaining pins  26  and  40  respectively. The straight forward arrangement of pin  26  and cutout  68  facilitate the interchangeable aspect of the punch  22   a,b  and alignment of the punch  22   a,b  in the bores  24 ,  25 . Correspondingly, the arrangement of key  54  and key-way  50 , with retaining screw  40 , facilitate the interchangeability of the mandrel  18   a,b  to correspond with that of the punch  22   a,b . It should be noted that the number of fasteners for securing the punch  22   a,b  and the mandrel  18   a,b  in the punch unit  10  are reduced, thereby facilitating the setup and adaptability of the unit  10  for a variety of different hole geometries. The leg  50 , retaining screw  40 , and retaining pin  26  are situated in area of the punch unit  10  easily accessible by the operator, in order to facilitate the changing of the tool and die assembly  17 .  
         [0022]    It is recognized that the retaining screw  40 , the key-way  50  and the retaining pin  26  can be situated on other areas of the punch unit  10  then what is shown, so long as they are easily accessible by the operator. Furthermore, the securing arrangements of pin  26  with cutout  68  and screw  40  with key  54  can be different than what is shown in FIGS. 1, 2,  3 , so long as the arrangements provide for releaseably securing the mandrel  18   a,b  and the punch  22   a,b  in the correct position and orientation. It is also recognized that the male die member  28   a,b  can be situated on the mandrel  18   a,b  and the female die member  30   a,b  on the punch  22   a,b .  
         [0023]    A further embodiment for securing the mandrel  18   a,b  is shown in FIG. 4, wherein like numerals with a suffix “c” refer to similar elements to those of FIG. 1, a retaining screw  40   c  and corresponding bores  42   c  and  46   c  are offset from an axis  78  of mandrel  18   c . This arrangement provides for angular orientation and securement of the mandrel  18   c  with respect to the mandrel support  16   c  and vertical axis  56   c.    
         [0024]    A further embodiment for an interchangeable mandrel  18   d  is shown in FIGS. 5 and 6, wherein like numerals with a suffix “d” refer to similar elements to those of FIG. 1. The mandrel  18   d  includes die insert  80 , which is appropriately sized to receive a corresponding female die insert  82   a,b,c . The inserts  82   a,b,c  are interchangeable with the same mandrel  18   d  and contain different hole geometries  84   a,b,c,  which are compatible with corresponding male die members (not shown). The die cavity  80  contains shoulders  86 , which support portions of an underside face  88  of the inserts  82   a,b,c.  The die cavity  80  also contains an ejection passage  90  to facilitate removal of the blanks  78 . In order to install or remove the inserts  82   a,b,c  with respect to the cavity  80 , a retaining screw  92  is received in bore  94  in the mandrel  18   d . The screw  92  has a threaded portion  96  which corresponds to a threaded bore  98  located on an end of the inserts  82   a,b,c.    
         [0025]    Use of the inserts  82   a,b,c  facilitates replacement of the female die member  82   a,b,c  as it wears out, rather than replacement of the entire mandrel  18   d . It is recognized that different hole geometries and securing arrangements of the insert  82   a,b,c  to the mandrel  18   d , other than what is shown, can be implemented without departing from the spirit and scope of the invention. It is also recognized that the male die member  28   a,b  can be attached to the punch  22   a,b  as inserts, if desired.  
         [0026]    Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.