Patent Publication Number: US-9409307-B2

Title: Punching device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation-in-Part (CIP) of U.S. patent application Ser. No. 13/024,852 filed on Feb. 10, 2011, which claims priority to Taiwanese Patent Application No. 099204033, filed on Mar. 8, 2010, and Chinese Patent Application No. 201020151904.1, filed on Mar. 25, 2010, which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a punching device, more particular to a punching device including a pair of driving levers for driving a punch to slide against a die for cutting a sheet. 
     2. Description of the Related Art 
     Referring to  FIG. 1 , Taiwanese Patent Application No. 81203592 discloses a conventional punching device  100  that is used in the craft industry for cutting a sheet (not shown), such as a paper sheet and a plastic sheet, in a predetermined pattern to form a craft article. The punching device  100  includes a base  11 , a punch  12 , a compression spring  13 , a pressing button  14 , and a cap  15 . The base  11  includes a bottom plate  111  and a supporting plate  112  parallel to and connected to the bottom plate  111  and cooperating with the bottom plate  111  to define a gap  10  for extension of the sheet therein. The bottom plate  111  is formed with a die hole  113  for passage of the punch  12  therethrough. The pressing button  14  is seated on the punch  12  for pressing the punch  12  against the compression spring  13  so as to move the punch  12  along a vertical axis (X) into and through the die hole  113  in the bottom plate  111 , thereby cutting the sheet. The compression spring  13  restores the punch  12  to its original position after punching. The cap  15  covers the punch  12  and the supporting plate  112  and is formed with a top opening for extension of the pressing button  14  therethrough. Since the force acted on the pressing button  14  is directly transmitted to the punch  12  in the vertical axis (X), it is laborious when using the aforesaid punching device to cut a thick sheet. 
     Referring to  FIG. 2 , U.S. Pat. No. RE38219 discloses a punching device  200  including a base  21 , a punch  22 , a compression spring unit  23 , a cap  24  and a pressing lever  25 . The base  21  has a bottom plate  211  and a supporting plate  212  disposed above and connected to the bottom plate  211  through a connecting wall  217  and cooperating with the bottom plate  211  to define a gap  213  therebetween for receiving a sheet (not shown) therein. The bottom plate  211  is formed with a die hole  214 . The supporting plate  212  has one end provided with a pivot seat  216 , and is formed with a through-hole  215  aligned with the die hole  214  for extension of the punch  22  therethrough and into the die hole  214 . The punch  22  has a bottom blade edge  221  for cutting the sheet. The compression spring unit  23  abuts against the supporting plate  212  and the punch  22  for restoring the punch  22  to its original position. The pressing lever  25  has a pivot end  251  pivoted to the pivot seat  216 , a pressing end  253  opposite to the pivot end  251 , and a driving protrusion  252  that is disposed between the pivot end  251  and the pressing end  253  and that is aligned with the punch  22  along a vertical axis (Y) perpendicular to the sheet. When the pressing end  253  of the pressing lever  25  is pressed, the driving protrusion  252  presses the punch  22  to move along the vertical axis (Y) into and through the die hole  214 , thereby cutting the sheet. 
     Although the pressing lever  25  of the punching device  200  permits a less force required to punch the sheet as compared to the previous conventional punching device  100 , it undesirably and considerably increases the length of the punching device  200  attributed to the length of the pressing lever  25 . Moreover, according to the lever principle, the shorter the distance between the pivot end  251  (fulcrum) and the driving protrusion  252  (load) and the longer the distance between the pivot end  251  and the pressing end  253  (effort), the more will be the mechanical advantage, i.e., the less effort is required. Since the contact between the driving protrusion  252  and the punch  22  is required to be located on the vertical axis (Y) in order to prevent imbalance problem for the punch  22  (inclination of the punch  22  or uneven movement of the punch  22 ) from occurring, the distance between the pivot end  251  and the driving protrusion  252  is fixed and cannot be reduced. As a consequence, the longer the distance between the pivot end  251  and the driving protrusion  252 , the longer the distance between the pivot end  251  and the pressing end  253  is required to maintain the same effort. In addition, since the pressing end  253  of the pressing lever  25  is located at one side of the punch device  200  and is relatively far from the vertical axis (Y), the dimensions of the base  21  are required to be enlarged in order to increase the stability of the punch device  200  and to prevent the punch device  200  from raising up or flipping over upon pressing of the pressing end  253 , thereby further increasing the overall size of the punch device  200 . 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a punching device that can easily punch a sheet without increasing the size of the punching device as encountered in the prior art. 
     According to the present invention, there is provided a punching device for cutting a sheet. The punching device comprises: a housing defining an inner housing space and having a surrounding frame part, an upper part and a flange part, the surrounding frame part having upper and lower end portions, the upper part being movably supported on the upper end portion of the surrounding frame part and having an abutting protrusion, the flange part extending transversely from the lower end portion of the surrounding frame part, being formed with a lower spring-holding member, and defining a flange hole; two opposite pivot seats protruding upwardly from the flange part into the inner housing space and opposite to each other in a first direction; a die part disposed below and operatively connected to the flange part; a punch unit including a punch head, an upper spring-holding member, and a punch, the upper spring-holding member protruding upwardly from the punch head, the punch being disposed between the pivot seats and extending downwardly from the punch head toward the die part; a spring extending between and abutting against the upper and lower spring-holding members, so that the punch unit can be supported movably on the flange part and that the punch is slidable through the flange hole and against the die part along a vertical axis substantially perpendicular to the first direction; and a pressing unit including two driving levers, each of which has a pivot end that is pivoted to a respective one of the pivot seats, a pressing end that is opposite to the pivot end, a first end segment that extends along a first line of its length direction from the pivot end, a second end segment that extends along a second line of its length direction from the pressing end, a middle segment that interconnects and that deflects from the first and second end segments, and a driving protrusion disposed between the pivot end and the pressing end and protruding therefrom toward the punch unit. The middle segment has curved first and second end portions that turn curvedly and respectively from the first and second end segments. The first lines, along which the first end segments extend, intersect each other at the vertical axis. The second lines, along which the second end segments extend, are substantially parallel to each other and are spaced apart from the vertical axis. The vertical axis is disposed between the driving protrusions of the driving levers. The driving protrusions of the driving levers are disposed in a symmetrical manner with respect to the vertical axis, and press against the punch unit to drive movement of the punch unit along the vertical axis toward the die part for cutting the sheet. The upper part is disposed on and abuts against the pressing ends of the driving levers, and is movable relative to the surrounding frame part along the vertical axis for pressing the driving levers to rotate relative to the surrounding frame part. The driving levers are rotatable relative to the surrounding frame part about first and second rotational axes, respectively, between an initial position and a cutting position. The first and second rotational axes are transverse to the first direction and the vertical axis. When the driving levers are disposed at the initial position, the abutting protrusion of the upper part is pushed by the pressing ends of the driving levers to abut against the upper end portion of the surrounding frame part by the urging action of the spring and in the meantime the driving levers extend upwardly and respectively from the pivot ends to the pressing ends and cross each other. When the driving levers are disposed at the cutting position, the abutting protrusion of the upper part is spaced apart from the upper end portion of the surrounding frame part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In drawings which illustrate embodiments of the invention, 
         FIG. 1  is a sectional view of a conventional punching device; 
         FIG. 2  is a sectional view of another conventional punching device; 
         FIG. 3  is an exploded perspective view of the first preferred embodiment of a punching device according to this invention; 
         FIG. 4  is an assembled perspective view illustrating a configuration of a portion of the first preferred embodiment; 
         FIG. 5  is a sectional view of the first preferred embodiment, illustrating an initial state where a pressing unit is disposed at an initial position; 
         FIG. 6  is a top view of the first preferred embodiment, illustrating the initial state of the pressing unit; 
         FIG. 7  is a sectional view of the first preferred embodiment, illustrating a cutting state where the pressing unit is disposed at a cutting position; 
         FIG. 8  is a top view of the first preferred embodiment, illustrating the cutting state of the pressing unit; 
         FIG. 9  is an exploded perspective view of the second preferred embodiment of the punching device according to this invention; 
         FIG. 10  is a sectional view of the second preferred embodiment, illustrating the initial state of the pressing unit; 
         FIG. 11  is a sectional view of the second preferred embodiment, illustrating the cutting state of the pressing unit; 
         FIG. 12  is a top view of the second preferred embodiment, illustrating the cutting state of the pressing unit; and 
         FIG. 13  is a top view of the third preferred embodiment of the punching device according to this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED. EMBODIMENTS 
     Before the present invention is described in greater detail with reference to the accompanying preferred embodiments, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure. 
     Referring to  FIGS. 3 to 8 , the first preferred embodiment of a punching device  300  for cutting a sheet of paper (not shown) according to the present invention is shown to include: a housing  3  defining an inner housing space  34  and having a surrounding frame part  37 , an upper part  36  and a flange part  33 , the surrounding frame part  37  having upper and lower end portions  371 ,  372 , the upper part  36  being movably supported on the upper end portion  371  of the surrounding frame part  37  and having a bottom peripheral end and an abutting protrusion  361  that protrudes outwardly from the bottom peripheral end, the flange part  33  being detachably and securely connected to and extending transversely from the lower end portion  372  of the surrounding frame part  37 , being formed with a plurality of lower spring-holding members  335 , and defining a flange hole  318 ; two pivot seats  332  that are opposite to each other in a first direction (T) and that protrude upwardly from the flange part  33  into the inner housing space  34 , each of the pivot seats  332  having a pair of C-shaped hooks; a die part  32  disposed below and operatively connected to the surrounding frame part  37 ; a punch unit  5  including a punch head  51 , a plurality of upper spring-holding members  55 , and a punch  52  extending downwardly from the punch head  51  toward the die part  32  and disposed directly above the die part  32  and between the pivot seats  332 , the upper spring-holding members  55  protruding upwardly from the punch head  51 ; a plurality of springs  431  extending between and abutting against the upper and lower spring-holding members  55 ,  335 , so that the punch unit  5  can be supported movably on the flange part  33  and that the punch  52  is slidable through the flange hole  318  and against the die part  32  along a vertical axis (Z) substantially perpendicular to the first direction (T); and a pressing unit  4  including two driving levers  41 , each of which has a pivot end  411  and a pressing end  412 . 
     The pivot ends  411  of the driving levers  41  are respectively pivoted to the C-shaped hooks of the pivot seats  332  so that the driving levers  41  are rotatable relative to the flange part  33  about first and second rotational axes (X 1 , X 2 ), respectively, between an initial position ( FIGS. 5 and 6 ) and a cutting position (see  FIGS. 7 and 8 ). The first and second rotational axes (X 1 , X 2 ) are transverse to the first direction (T) and the vertical axis (Z). The driving protrusion  413  of each of the driving levers  41  is disposed between the pivot end  411  and the pressing end  412 , and protrudes therefrom toward the punch unit  5 . The vertical axis (Z) is disposed between the driving protrusions  413  of the driving levers  41 . 
     The driving protrusions  413  of the driving levers  41  are disposed respectively at two sides of the vertical axis (Z) in a symmetrical manner with respect to the vertical axis (Z), and press against the punch unit  5  for driving movement of the punch unit  5  along the vertical axis (Z) toward the die part  2  for cutting the sheet. 
     The upper end portion  371  of the surrounding frame part  37  has a generally U-shaped cross-section, and defines an opening  3710  for extension of the upper part  36  therethrough. 
     The upper part  36  is disposed on and has a bottom end face that abuts constantly against the pressing ends  412  of the driving levers  41 . The upper part  36  is movable relative to the surrounding frame part  37  along the vertical axis (Z) for pressing the driving levers  41  to rotate relative to the flange part  33  and the surrounding frame part  37 . 
     The flange part  33  is generally rectangular in shape, has four corners, and is disposed directly above the die part  32 . The pivot seats  332  are disposed at two diagonally aligned ones of the corners, respectively. The die part  32  has a die hole  319  for extension of the punch  52  therethrough. In this embodiment, the die part  32  is magnetically attached to the flange part  33  through a magnetic unit so as to be operatively connected to the surrounding frame part  37  through the flange part  33 . The magnetic unit includes a plurality of magnets  61  which are secured to the die part  32  and the flange part  33 , so that the sheet of paper can be placed on the die part  32  for punching before the die part  32  is magnetically attached to the flange part  33  to sandwich the sheet of paper therebetween. 
     Referring to  FIGS. 5 to 8 , the driving levers  41  cross each other and the vertical axis (Z) and are disposed in a symmetrical manner. Each of the driving levers  41  includes first and second end segments  415 ,  416  and a middle segment  417  that interconnects and that deflects obliquely from the first and second end segments  415 ,  416  so that the first and second end segments  415 ,  416  are offset from each other. The middle segment  417  has curved first and second end portions  4171  that turn curvedly and respectively from the first and second end segments  415 ,  416 . The first end segments  415  of the driving levers  41  extend respectively along first lines (u 1 , v 1 ) of their length direction from the pivot ends  411  of the driving levers  41 . The second end segments  416  of the driving levers  41  extend respectively along second lines (u 2 , v 2 ) of their length direction from the pressing ends  412  of the driving levers  41 . The first lines (u 1 , v 1 ) intersect each other at the vertical axis (Z). The second lines (u 2 , v 2 ) are substantially parallel to each other, and are spaced apart from the vertical axis (Z). 
     When the driving levers  41  are disposed at the initial position, the abutting protrusion  361  of the upper part  36  is pushed by the pressing ends  412  of the driving levers  41  to abut against the upper end portion  371  of the surrounding frame part  37  by the urging action of the springs  431  and in the meantime the driving levers  41  extend upwardly and respectively from the pivot ends  411  to the pressing ends  412  and cross each other in such a manner that the second end segments  416  extend upwardly and respectively from the middle segments  417  in a direction inclined to the first direction (T) and that the second end portions  4172  of the middle segments  417  overlap each other in a second direction (Y), which is perpendicular to the vertical axis (Z) and the first direction (T). When the driving levers  41  are disposed at the cutting position, the abutting protrusion  361  of the upper part  36  is spaced apart from the upper end portion  271  of the surrounding frame part  37  and in the meantime the second end segment  416  of one of the driving levers  41  overlaps the first end segment  415  of the other one of the driving levers  51  in the second direction (Y) and the second end segment  416  of said the other one of the driving levers  41  overlaps the first end segment  415  of said one of the driving levers  51  in the second direction (Y). In addition, the second end portions  4172  of the middle segments  417  are misaligned with each other in the second direction (Y) when the driving levers  41  are disposed at the cutting position. 
     The diagonal relation of the relative position between the driving levers  41  and the configuration of the first and second end segments  415 ,  416  and the middle segment  417  permits achievement of a compact design of the punching device. 
     The extension of the driving levers  41  to cross each other results in an increase in the lever arm of force and permits the driving protrusions  413  to be positioned at positions closer to the vertical axis (Z), which has the advantage of preventing the punch  22  from becoming obliquely relative to the vertical axis (Z) due to unbalanced forces acting on the pressing ends  412  of the driving levers  41  during punching. In addition, the extension of the driving levers  41  to cross each other further permits the pressing ends  412  of the driving levers  41  to have sufficient heights relative to the flange part  33 , which is advantageous in providing a sufficient traveling distance for the pressing ends  412  of the driving levers  41  during a punching operation. 
       FIGS. 9 to 12  illustrate the second preferred embodiment of the punching device  300  according to this invention. The second preferred embodiment differs from the previous embodiment in that each of the pivot seats  332  is disposed at a middle position between two adjacent ones of the corners. 
       FIG. 13  illustrates the third preferred embodiment of the punching device  300  according to this invention. The third preferred embodiment differs from the previous embodiments in that the first and second end segments  415 ,  416  of each of the driving levers  41  extend in the same length direction and that the pivot seats  332  are offset from each other in the length direction of the first and second end segments  415 ,  416 . 
     With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention.