Abstract:
A first score line ( 430 ) is provided with a modified groove width portion ( 435 ) in which the groove width differs from the groove width of other portions. This modified groove width portion ( 435 ) is formed by imparting curvature to a point of a first side surface ( 430 B) and this portion of a second side surface ( 430 C) are respectively distended in an outward direction . To describe further, the modified groove width portion ( 435 ) is formed by forming respective recessed portions in the first side surface ( 430 B) and the second side surface ( 430 C). In so doing, rupture of a panel can take place in satisfactory fashion along a score line having a branched portion.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a can lid. and a beverage can. 
       BACKGROUND ART 
       [0002]    A beverage can, in which an opening portion functioning as a tap is formed by cracking of a panel at a score line caused by applying pressure of a tab on part of the panel, has been suggested (for example, refer to Patent Document 1). 
       CITATION LIST 
     Patent Literature 
       [0003]    Patent Document Japanese Patent Application Laid-Open Publication No. Sho 51-82188. 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    Typically, a score line is formed on a surface of a panel in a can lid usable for a beverage can. Cracking of the panel progresses along the score line in forming an opening portion in the can lid. Here, in the case where the score line is branched in the middle, cracking of the panel occurs at. each of the plural score lines on the downstream side beyond the branch part, and consequently an opening portion is formed in the can lid. 
         [0005]    In the case where plural score lines are formed on the downstream side beyond the branch part, cracking start timing when cracking starts at each of the plural score lines may affect the formation of the opening portion in some cases. If the cracking start timing differs from the predetermined timing, an opening portion in a state different from the intended state may be formed in some cases because cracking of the panel along some of the score lines may be difficult to occur. 
         [0006]    An object of the present invention is to appropriately crack the panel along the score line having the branch part. 
       Solution to Problem 
       [0007]    The can lid to which this invention is applied is a can lid including: a. panel that is attachable to an opening portion of a can body; a score line that is formed on the panel, that extends toward a predetermined extending direction, then is branched at a branch part, and further extends toward a plurality of directions, that includes a first branched score line and a second branched score line on a downstream side beyond the branch part in the extending direction, and that promotes cracking of the panel; and a speed decreasing unit that is provided so as to correspond to at least one branched score line of the first branched score line and the second branched score line, and that temporarily decreases progress rate in progressing cracking of the panel along the one branched score line. 
         [0008]    Here, the one branched score line is formed by a groove on the surface of the panel, the one branched score line has any one of a part where the groove decreases in width and a part where the groove increases in width, and the progress rate is temporarily decreased at any one of the part where the groove decreases in width and the part where the groove increases in width. In this case, the branched score line partially decreases in width or partially increases in width, and thereby the progress rate in progressing cracking of the panel along the branched score line can be temporally decreased. 
         [0009]    Further, the one branched score line is formed by a groove on the surface of the panel, the groove includes a bottom part, a first side surface, and a second side surface, the first side surface being located on one side of the groove in the width direction of the groove and facing the inside of the groove, the second side surface being located on the other side of the groove in the width direction of the groove and facing the inside of the groove, any one of a convex portion and a concave portion is formed on at least one side surface of the first side surface and the second side surface, and the progress rate is temporarily decreased at a part where any one of the convex portion and the concave portion is provided. In this case, the convex portion or the concave portion is provided on the side surface of the groove forming the branched score line, and thereby the progress rate in progressing cracking of the panel along the branched score line can be temporally decreased. 
         [0010]    Furthermore, the one branched score line is formed by a groove on the surface of the panel, the groove includes a bottom part, a first side surface, and a second side surface, the first side surface being located on one side of the groove in the width direction of the groove and facing the inside of the groove, the second side surface being located on the other side of the groove in the width direction of the groove and facing inside of the groove, a first section and a second section are provided on at least one side surface of the first side surface and the second side surface, and a step is formed between the first section and the second section, the first section being located to be opposed to a corresponding section of the other side surface, the second section being disposed at a different position from the first section in the extending direction. of the groove and being located to be close to the other side surface in comparison with the first section, and the progress rate is temporarily decreased at a part where the step is provided. In this case, the step is formed on the side surface of the groove forming the branched score line, and thereby the progress rate in progressing cracking of the panel along the branched score line can be temporally decreased. 
         [0011]    Still furthermore, the one branched score line is formed to change the extending direction in the middle of extending toward the downstream side of the extending direction, and the progress rate is temporarily decreased at a part where the extending direction of the one branched score line is changed. In this case, the extending direction of the branched score line is changed in the middle, and thereby the progress rate in progressing cracking of the panel along the branched score line can be temporally decreased. 
         [0012]    From another standpoint, the can lid to which this invention is applied is a can lid including: a panel that is attachable to an opening portion of a can body; a score line that is formed on the panel, that extends toward a predetermined extending direction, then is branched at a branch part, and further extends toward a plurality of directions, that comprises a first branched score line and a second branched score line on a downstream side beyond the branch part in the extending direction, and that promotes cracking of the panel, and a unit that is provided to correspond to at least one branched score line of the first branched score line and the second branched score line, d that temporarily delay cracking of the panel progressing along the one branched score line. 
         [0013]    In the case where this invention is taken as a beverage can, the beverage can to which this invention is applied is a beverage can including: a can body that contains drink, and a can lid that is attached to the can body. Here, the can lid is the aforementioned can lid. 
       Advantageous Effects of Invention 
       [0014]    According to the present invention, it is possible to appropriately crack the panel along the score line having the branch part. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]      FIG. 1  is a top view of a beverage can to which the exemplary embodiment is applied. 
           [0016]      FIGS. 2A to 2D  are views illustrating the tab. 
           [0017]      FIG. 3  is a front view of the can lid before the tab is attached thereto. 
           [0018]      FIGS. 4A to 4F  are views illustrating states of the can lid during operation of the tab. 
           [0019]      FIG. 5  is a view illustrating cracking of the panel. 
           [0020]      FIG. 6  is an enlarged view of the connection between the first score line and the second score line. 
           [0021]      FIG. 7  is a cross-sectional view taken along a line VII-VII in  FIG. 6 . 
           [0022]      FIG. 8  is an enlarged view of the connection between the first score line and the second score line. 
           [0023]      FIGS. 9A to 9H  are views illustrating other shapes of the first score line. 
           [0024]      FIG. 10  is a view illustrating another configuration example of the can lid. 
           [0025]      FIG. 11  is a view illustrating still another configuration example of the can lid. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to attached drawings. 
         [0027]      FIG. 1  is a top view of a beverage can  100  to which the exemplary embodiment is applied. As shown in the figure, the beverage can  100  includes: a container body (can body)  200  that has an opening portion at the upper part and a bottom at the lower part, and that is formed into a cylinder; and a can lid  300  that is attached to the opening portion of the container body  200 , and that covers the opening portion. Note that, drink such as refreshing beverage, soda, or alcohol is contained in the inside of the beverage can  100 . 
         [0028]    To the can lid  300 , there is provided a panel  400  which is formed into a disk, functions as a basal plate, and is attachable to the opening portion of the container body  200 . A tab  500  which is operable by a user is attached to the can lid  300 . One end part of the tab  500  (upper end part in the figure is operated (pulled up) by a user, and thereby the other end part (front end part) of the tab  500  is pressed onto a predetermined area (which will be described below in detail) of the panel  400  to apply a pressure to the panel  400 . Note that, the upper end part of the tab  500  in the figure is referred to as an operation target part  505 , and the lower end part of the tab  500  in the figure is referred to as a front end part  510 , in this description. 
         [0029]    The tab  500  is secured to the panel  400  with a rivet  900  provided at a position displaced from the central part of the panel  400 . That is to say, the tab  500  is secured to the panel  400  with the rivet  900  provided in an eccentric state with respect to the panel  400 . Further, the tab  500  has a part located between the operation target part  505  and the front end part  510 , the part being secured to the panel  400  with the rivet  900 . 
         [0030]    Note that, in the exemplary embodiment, description will be given for the case where the tab  500  is secured to the panel  400  with the rivet  900  provided at the position displaced from the central part of the panel  400  as one example. However, the tab  500  can be secured to the panel  400  with the rivet  900  provided at the central part of the panel  400 . Additionally, in the exemplary embodiment, the tab  500  having the front end part  510  formed into an arc is exemplified. However, the tab  500  may be formed into a rectangle. In this case, the front end part  510  of the tab  500  is linearly formed. 
         [0031]    With reference to  FIGS. 2A to 2D  (views illustrating the tab  500 ), the tab  500  will be further described. 
         [0032]    Note that,  FIG. 2A  is a front view of the tab  500 , and  FIG. 2B  is a view of the tab  500  seen from an arrow IIB direction in  FIG. 2A .  FIG. 2C  is a view of the rear surface of the tab  500 .  FIG. 2D  is a view of the tab  500  seen from an arrow IID direction in  FIG. 2A . 
         [0033]    The tab  500  includes a tab body  520  formed into a plate and a. rectangle-like shape, as shown in  FIG. 2A . Note that, in the exemplary embodiment, a bending process (curl process) has been performed on the outer peripheral edge of the tab body  520  as shown in  FIG. 2D , and thus the outer peripheral edge of the tab body  520  is curled inward. That is to say, curl portions are formed on the edge provided to four sides of the tab body  520 . 
         [0034]    Thereby, in the exemplary embodiment, the flexural rigidity of the tab  500  is enhanced. Further, a penetration hole (finger hole)  530  into which a finger of a user is insertable is formed on the side (operation target part  505  side) opposite to the side where the front end part  510  is provided in the tab  500 , as shown in  FIG. 2A . Furthermore, an insertion hole  540  into which a protrusion  420  (to be described later) provided in the panel  400  is insertable is formed on the front end part  510  side in the tab  500 . Still furthermore, a penetration part  560  that is formed into a U-shape and penetrates the tab body  520  is provided around the insertion hole  540 . 
         [0035]    A first slit  521  is formed in one curl portion provided, along the longitudinal direction of the tab  500  out of the four curl portions provided to the four sides of the tab body  520 . A second slit  522  is formed in another curl portion also provided along the longitudinal direction of the tab  500  out of the four curl portions. A groove  523  is formed along the lateral direction of the tab  500  at a part between the first slit  521  and the second slit  522  in the tab body  520 . 
         [0036]    The first slit  521 , the second slit  522  and the groove  523  are provided on the same straight line. Further, the first slit  521 , the second slit  522 , and the groove  523  are provided along the width direction of the tab  500 . Furthermore, the first slit  521 , the second slit  522 , and the groove  523  are disposed between the insertion hole  540  and the penetration hole  530 . In the exemplary embodiment, the first slit  521 , the second slit  522 , and the groove  523  are formed in this manner, and the rigidity al rigidity) at the parts where they are formed decreases. 
         [0037]    Thus, the tab  500  starts to be folded in response to application of a load on the operation target part  505  side of the tab  500 , as shown in  FIG. 2B . Note that, in the exemplary embodiment, the groove  523  is formed between the first slit  521  and the second slit  522  to decrease the rigidity at this part. However, the configuration is not limited to the groove, and performing a bending processing can decrease the rigidity, for example. Moreover, the groove  523  is not essential, and may be omitted. 
         [0038]    Note that, in the case where a load acting in the direction opposite to the arrow direction shown in  FIG. 2B  is applied on the operation target part  505  (the case where the load acting in the left direction in the figure is applied on the operation target part  505 ), two split surfaces due to the first slit  521  and the like (parts included in the tab  500 , and located on both sides of the first slit  521  and the like) face each other, and the tab  500  is prevented from being folded. 
         [0039]      FIG. 3  is a front view of the can lid  300  before the tab  500  is attached thereto. 
         [0040]    The can lid  300  in the exemplary embodiment includes a panel  400  formed into a disk. The panel  400  has an outer peripheral edge  410  on which a bending process has been performed. In the exemplary embodiment, a so-called scam process is performed on the outer peripheral edge  410  and an upper edge part (not shown) of the container body  200  (refer to  FIG. 1 ) in the state where the outer peripheral edge  410  and the upper edge part are in contact with each other. Thereby, the can lid  300  (the panel  400 ) is secured to the upper edge part of the container body  200 . 
         [0041]    In the can lid  300 , a protrusion (nipple)  420  which is flattened at securing the tab  500  to the panel  400  and becomes the aforementioned rivet  900  (refer to  FIG. 1 ) is formed. The protrusion  420  is provided at a part displaced from the central part CP of the panel  400 . A first score line  430  formed into a U-shape is formed on the surface of the panel  400 . 
         [0042]    The first score line  430  is constituted by a groove formed on the surface of the panel  400 , and has a function for guiding cracking of the panel  400  (to be mentioned later). That is to say, the first score line  430  can be taken as a planned cracking line where the panel  400  is planned to crack. More specifically, the first score line  430  has a function for promoting the cracking of the panel  400  caused by application of a pressure of the tab  500  onto the panel  400  so that the cracking occurs at the predetermined part of the panel  400 . 
         [0043]    The first score line  430  is formed to expand toward the outer peripheral edge  410  side of the panel  400  from the central part side of the panel  400 , and is formed into a I-shape when the panel  400  is viewed from the front side. Further, the first score line  430  has one end part  431  and the other end part  432  on the central part CP side of the panel  400 , and a top part  433 A on the outer peripheral edge  410  side of the panel  400 . Note that a region RA to be pressed by the tab  500 , which is included in the panel  400 , is located within a region surrounded by the first score line  430 , in the exemplary embodiment. 
         [0044]    The one end part  431  of the first score line  430  is disposed on one region side (the left region in the figure) out of two regions opposed to each other with respect to a center line CL of the tab  500  (center line along the longitudinal direction of the tab  500 ) (also refer to  FIG. 1 ). On the other hand, the other end part  432  is disposed on the other region side (the right region in the figure) out of the two regions opposed to each other with respect to the center line CL. In the exemplary embodiment, the first score line  430  is formed so as to be symmetric with respect to the center line CL of the tab  500  as the symmetry axis. 
         [0045]    By separately providing the one end part  431  and the other end part  432 , a discontinuous part where the first score line  430  is not formed is provided between the one end part  431  and the other end part  432  in the panel  400 . By providing the discontinuous part, a tongue part which will be mentioned later is not detached from the panel  400 , and is kept to be attached to the panel  400 . Note that the center line CL of the tab  500  passes through the central part CP of the panel  400  and the protrusion  420  formed in the panel  400 , as shown in  FIG. 3 , in the exemplary embodiment. 
         [0046]    In the exemplary embodiment, in the case where a first virtual line KL 1  taking as a virtual line orthogonal to the center line CL and. passing through the protrusion  420  (rivet  900 ) is assumed to be set, the one end part  431  and the other end part  432  are located on the central part CP side of the panel  400  relative to the first virtual line KL 1 . 
         [0047]    In the exemplary embodiment, the top part  433 A is located in one region out of two regions opposed to each other with respect to a second virtual line KL 2  orthogonal to the center line CL and passing through the central part CP of the panel  400 , and the one end part  431  and the other end part  432  are located in the other region, as shown in  FIG. 3 . 
         [0048]    Further, the protrusion  420  which becomes the rivet  900  is provided. in a part surrounded by the first score line  430  in the panel  400 , and is located on the top part  433 A side with respect to the one end part  431  and the other end part  432  of the first score line  430 . The first score line  430  has a curve part  433  as shown in  FIG. 3 . The first score line  430  includes the curve part  433  as shown in  FIG. 3 . The curve part  433  expands toward the side where the protrusion  420  is provided while connecting the one end part  431  and the other end part  432 , and passes on the outer peripheral edge  410  side of the panel  400  with respect to the protrusion  420 . The curve part  433  has the top part  433 A at a point where the curve part.  433  intersects with the center line CL. 
         [0049]    In the exemplary embodiment, in response to operation of the tab  500  by a user, the region surrounded by the first score line  430  is pressed by the tab  500 , and cracking of the panel  400  occurs at the section where the first score line  430  is formed (which will be mentioned later in detail). Thereby, the region within the first score line  430  becomes a tongue-shaped part, and the region is folded toward the inside of the beverage can  100 . Thereby, an opening portion functioning as a tap is formed. on the beverage can  100 . 
         [0050]    Note that, hereinbelow in this description, the aforementioned tongue-shaped part formed by the cracking occurring at the first score line  430  may be referred to as a tongue part in some cases. 
         [0051]    In other words, the inside region surrounded by the first score line  430  is pressed by the tab  500 , and is separated from the panel  400  because of cracking of the first score line  430 . However, since the cracking of the score line does not occur at the aforementioned discontinuous part between the one end part  431  and the other end part  432  of the first score line  430 , where the score line is not formed, there is no problem about the separation from the panel  400 . That is, the inside region surrounded by the first score line  430  bends while the connection with the panel  400  is maintained at the discontinuous part, and is pressed down to the inside of the beverage can  100 . 
         [0052]    In the exemplary embodiment, the second score line  450  is formed on the surface of the panel  400 . The second score line  450  is also constituted by a groove formed on the surface of the panel  400 , and has a function for guiding the cracking of the panel  400 . The second score line  450  is provided within a region where the top part  433 A (the top part  433 A of the first score line  430 ) is provided, out of two regions opposed to each other with respect. to the first virtual line KL 1 . 
         [0053]    The second score line  450  has one end part  451  and the other end part  452 . Here, the other end part  452  of the second score line  450  is connected to the curve part  433  of the first score line  430 . Thus, in the exemplary embodiment, the score line is branched at the part where the first score line  430  and the second score line  450  are connected. 
         [0054]    The other end part  452  of the second. score line  450  is connected. to the part which is included in the curve part  433  of the first score line  430  and which is located between the center line CL, and the first virtual line KL 1 . More specifically, the other end part  452  of the second score line  450  is connected to the part located between the top part  433 A and the other end part  432  in the first score line  430 . Further, the either end part  452  of the second score line  450  is connected to the part other than the part where the top part  433 A is provided, in the first score line  430 . 
         [0055]    More specifically, the connection between the first score line  430  and the second score line  450  is provided in a part other than the intersection KP where the center line CL and the first score line  430  intersect with each other. In the exemplary embodiment, the second score line  450  extends toward the inside of the region surrounded by the first score line  430  from the connection with the first score line  430 . 
         [0056]    In the exemplary embodiment, the connection between the first score line  430  and the second score line  450  is provided on the side where the aforementioned intersection KP is provided, with respect to the first virtual brie KL 1 . disposed to be orthogonal to the center line CL. In other words, in the exemplary embodiment, the connection between the first score line  430  and the second score line  450  is provided on the side where the region RA is located, with respect to the first virtual brie KL 1  disposed to be orthogonal to the center line CL. 
         [0057]    In the exemplary embodiment, the distance between the one end part  431  of the first score line  430  and the connection between the first score line  430  and the second score line  450  is greater than the distance between the other end part  432  of the first score line  430  and the connection. More specifically, the length of the part located between the one end part  431  and the connection in the first score line  430  is greater than the length of the part located between the other end part  432  and the connection in the first score line  430 . 
         [0058]    Note that, in the exemplary embodiment, the description has been given in the case where the second score line  450  is formed to extend from the central part side of the panel  400  toward the bottom-right direction in the figure. However, the second score line  450  may be alternatively formed to extend toward the bottom-left direction in the figure. In this case, the second score line  450  is connected to the part located between the top part  433 A and the one end part  431  in the first score line  430 . 
         [0059]    The one end part  451  of the second score line  450  is provided in the vicinity of the protrusion  420 . Further, the one end part  451  of the second score line  450  is disposed on one region side out of two regions opposed to each other with respect to the center line CL, and the other end part  452  of the second score line  450  is disposed on the other region side out of these two regions. 
         [0060]    Further, the second score line  450  has a straight-line part  453  extending from the other end part  452  toward the protrusion  420 . In addition, the second score line  450  has the curve part  454  which is connected to the straight-line part  453 , which keeps a distance from the protrusion  420  formed into a cylinder, and which is formed along the outer circumferential edge of the protrusion  420 . 
         [0061]    The curve part  454  of the second score line  450  is formed between the protrusion  420  and the first score line  430 . More specifically, the curve part  454  is formed between the top part  433 A of the first score line  430  and the protrusion  420 , That is to say, the curve part  454  of the second score line  450  is disposed between the protrusion  420  and the first score line  430  on the center line CL. 
         [0062]    Further, the curve part  454  is provided to pass between the protrusion  420  and the region RA included in the panel and to be pressed by the tab  500 . That is to say, in the exemplary embodiment, the second score line  450  is provided to pass the side where the protrusion  420  (rivet  900 ) is provided with respect to the aforementioned region RA, and to pass between the region RA and the protrusion  420 . 
         [0063]    The curve part  454  of the second score line  450  is provided to intersect with the center line CL. Specifically, the second score line  450  in the exemplary embodiment passes between the region RA and the protrusion  420 , then extends along the direction intersecting with the center line CL, and is connected to the first score line  430 . More specifically, the second score line  450 , which extends along the direction intersecting with the center line CL and toward the first score line  430 , passes beside the region RA. 
         [0064]    After passing between the region RA and the protrusion  420 , the second score line  450  extends so as to gradually get away from the first virtual line KL 1 , and is connected to the first score line  430 . 
         [0065]    Here, the can lid  300  is further described with reference to FIGS,  4 A to  4 F (views illustrating states of the can lid  300  during operation of the tab  500 ). Note that, each of  FIGS. 4A to 4F  illustrates two states of the can lid  300 , including a state when the can lid  300  is seen from the front side arid a state when the can lid  300  is seen from the lateral side. 
         [0066]    In the exemplary embodiment, when the operation target part  505  (rear end part) (refer to  FIG. 1 ) of the tab  500  is pulled up by a user, the front end part  510  of the tab  500  presses the region RA (refer to  FIG. 3 ) located between the curve part  454  of the second score line  450  and the top part  433 A of the first score line  430 . In response to the pressure onto the region RA with the tab  500 , firstly, the panel  400  cracks at the curve part  454  of the second score line  450  which is provided to pass between the region RA and the rivet  900  (protrusion  420 ) (refer to  FIG. 4B ). 
         [0067]    Then, the cracking of the panel  400  progresses along the second score line  450  to the connection between the first score line  430  and the second score line  450 , as shown in  FIG. 4C . Thereafter, in the exemplary embodiment, cracking of the panel  400  progresses from the connection toward the one end part  431  of the first score line  430 , and from the connection toward the other end part  432  of the first score line  430 , as shown in  FIG. 4D . 
         [0068]    That is to say, since the score line is configured to be branched at the connection between the first score line  430  and the second score line  450  in the exemplary embodiment, the score line that has extended to the connection along the second score line  450  is divided after passing through the branched area (branch part), and further extends toward the one end part  431  and the other end part  432 . 
         [0069]    More specifically, after the score line in the exemplary embodiment is branched at the connection (branch part) and is divided, part of the score line is regarded as a first branched score line, and the another part thereof is regarded as a second branched score line. The first branched score line extends toward the one end part  431 , and the second branched score line extends toward the other end part  432 . 
         [0070]    After that, in the exemplary embodiment, the tab  500  is pressed down toward the inside direction of the beverage can  100  by the user. Thereby, cracking of the panel  400  further progresses o the one end part  431  and the other end part  432  of the first score line  430  as shown in  FIG. 4E . Consequently, the region surrounded by the first score line  430  becomes the tongue part. The tongue part is folded at the base of the tongue part (the part located between the one end part  431  and the other end part  432  of the first score line  430 ), and the tongue part enters the inside of the beverage can  100 . 
         [0071]    Thereby, an opening portion functioning as a tap is formed on the beverage can  100 . Then, the user operates the operation target part  505  side of the tab  500 , and the tab  500  is folded as shown in  FIG. 4F . Thus, the operation target part  505  side of the tab  500  is located along the panel  400  of the can lid  300 . Note that, in this case, obstacle at drinking is avoided because of no projection of the operation target part  505  side. 
         [0072]    Here, in the exemplary embodiment, since the tab  500  is folded in this manner, the state where the front end part  510  of the tab  500  is placed into the inside of the beverage can  100  is maintained. That is to say, even if the tab  500  having been pulled up is laid along the panel  400 , the state where the front end part  510  of the tab  500  is placed into the inside of the beverage can  100  is maintained. Thereby, the formed opening portion is prevented from being occupied by the front end part  510  of the tab  500 , and a larger opening portion is obtained. 
         [0073]    Note that, although the foldable tab  500  has been described, as one example in the exemplary embodiment, the tab  500  that is not foldable can be used as a matter of course. Note that, in the case where the tab  500  that is not foldable is used, it is preferable to reduce the projecting amount of the operation target part  505  of the tab  500 . 
         [0074]    Cracking of the panel  400  occurring at the first score line  430  and the second score line  450  will be further described with reference to  FIG. 5  (a view illustrating cracking of the panel  400 ). 
         [0075]    In the exemplary embodiment, as mentioned above, when a user pulls up the operation target part  505  of the tab  500 , the region RA (refer to  FIG. 3 ) located between the curve part  454  of the second score line  450  and the top part  433 A of the first score line  430  (refer to  FIG. 3 ) is pressed by the tab  500 . Thereby, the panel  400  cracks firstly at the curve part  454  (refer to  FIG. 5 ) of the second score line  450 . 
         [0076]    Then, the cracking of the panel  400  progresses along the second score line  450 , and the cracking of the panel  400  progresses to the connection between the first score line  430  and the second score line  450 . Thereafter, cracking of the panel  400  starts at the first score line  430 . Specifically, the cracking of the panel  400  occurs in the region denoted by a reference numeral  4 C in the first score line  430 . 
         [0077]    More specifically, in the exemplary embodiment, the tab  500  is pressed onto the region RA, and the region RA is pressed toward the inside direction of the beverage can  100 . At this time, the protrusion  420  is pulled toward the outside direction. of the beverage can  100  (front side direction of the paper surface in  FIG. 5 ) by the tab  500 . Thereby, a part denoted by a reference numeral  4 B in  FIG. 5  is pulled toward. the outside direction of the beverage can  100 . As a result, shearing force acts on the region denoted by a reference numeral  4 C, and the panel  400  cracks in the region denoted by the reference numeral  4 C. That is to say, the panel  400  cracks at the part included in the first score line  430  and located on the other end part  432  side beyond the connection. 
         [0078]    In the exemplary embodiment, the tab  500  continues to press the region RA, and thereby part of the panel  400  denoted by a reference numeral  4 A is pressed toward the inside direction of the beverage can  100 . Consequently, shearing force acts on a region denoted by a reference numeral  4 D, and the panel  400  cracks in the region denoted by the reference numeral  4 D. That is to say, the panel  400  cracks at the part included in the first score line  430  and located on the one end part  431  side beyond the connection. 
         [0079]    Thereafter, in the exemplary embodiment, the tab  500  is pressed down toward the inside direction of the beverage can  100  by the user, and thereby cracking of the panel  400  further occurs in the first score line  430 . Specifically, the panel  400  cracks in two regions denoted by reference numerals  4 E and  4 F in the figure. Further, in the exemplary embodiment, the tongue part is folded at the bottom of the tongue part (part located between the one end part  431  and the other end part  432  of the first score line  430 ). Thereby, the tongue part enters into the inside of the beverage can  100 , and an opening portion is formed in the beverage can  100 . 
         [0080]    In the case where the panel  400  cracks earlier on the other end part  432  side beyond the connection and then cracks on the one end part  431  side as described in the exemplary embodiment, an operation load when a user operates the tab  500  decreases. 
         [0081]    For example, in the case where cracking of the panel  400  occurs simultaneously on the one end part  431  side beyond the connection and the other end part  432  side beyond the connection, cracking of the panel  400  starts simultaneously at the two parts. In this case, an operation load required for cracking at the two parts is necessary to be applied with the tab  500 , and thus the operation load, of the tab  500  increases. 
         [0082]    On the other hand, in the case where the panel  400  cracks earlier on the other end part  432  side beyond the connection and then cracks on the one end part  431  side beyond the connection as described in the exemplary embodiment, only an operation load required for cracking at one part is applied with the tab  500 . In this case, the operation load of the tab  500  is smaller than in the case where the panel  400  cracks simultaneously at the two parts. 
         [0083]    Further, in the case where the panel  400  cracks earlier on the other end part  432  side beyond. the connection, and then cracks on the one end part  431  side beyond the connection as described in the exemplary embodiment , a user more securely forms an opening portion (tap) in the can lid  300 . 
         [0084]    Here, if the panel  400  cracks earlier on the one end part  431 . side beyond the connection, the panel  400  is difficult to crack from the connection toward the other end part  432  side. Thus, the region located inside the first. score line  430  may not entirely become an opening portion, and an opening portion in an imperfect state may be formed in some cases. 
         [0085]    More specifically, in the case where the panel  400  cracks earlier on the one end part  431  side beyond the connection, the front end part  510  of the tab  500  first enters into the inside of the beverage can  100 . In this case, the support of the front end part  510  by the panel  400  (support from below) is lost. If the support of the front end part  510  is lost in. this manner, the protrusion  420  is difficult to be pulled (toward the outside direction of the beverage can  100 ) by the tab  500 . Thus, in this case, shearing force is difficult to act on the aforementioned region denoted by the reference numeral  4 C, and the panel  400  is difficult to crack in the region denoted by the reference numeral  4 C. 
         [0086]    Further, if cracking of the panel  400  occurs earlier on the one end part  431  side beyond the connection, tilt or rotation of the tab  500  is caused, and thereby an opening portion is difficult to be formed. More specifically, in the case where the panel  400  cracks earlier on the one end part  431  side beyond the connection, a small opening portion (hereinafter referred to as “small opening”) is formed in the region denoted by the reference numeral  4 A in  FIG. 5 , and the front end part  510  of the tab  500  enters into the inside of the beverage can  100  through the small opening. Then, in response to the entrance of the front end part  510  of the tab  500  in this manner, the edge of the small opening and the outer peripheral edge of the tab  500  make a contact with each other at the part denoted by the reference numeral  1 A in  FIG. 1 . 
         [0087]    In this case, the contact part where the edge of the small opening and the outer peripheral edge of the tab  500  make a contact with each other is located on the position displaced from the center line CL of the tab  500 . Thus, if the operation of the tab  500  (pulling-up of the operation target part  505  side) is continued, the tab  500  tilts. In addition, in this case, rotation of the tab  500  about the rivet  900  may be caused in some cases. Upon occurrence of tilt or rotation of the tab  500  in this manner, shearing force is difficult to act on the aforementioned region denoted by the reference numeral  4 C, and the opening portion is difficult to be formed in the panel  400 . 
         [0088]    Moreover, in the case where the panel  400  cracks on the one end part  431  side from the connection and does not crack from the connection to the other end part  432  side at all, the region denoted by the reference numeral  4 A of the panel  400  is pressed into the inside of the beverage can  100 , and the front end part  510  of the tab  500  starts to press the edge of the small opening at the part denoted by the reference numeral  1 A in  FIG. 1 . At this time, the edge of the small opening makes a contact with a part of the front end part  510  of the tab  500 , the part being displaced from the center line CL. Thus, the reaction force from the edge of the small opening against the pressure is an eccentric load to the tab  500 , and the tab  500  may tilt and rotate about the rivet  900  in the clockwise direction. In this case, the front end part  510  of the tab  500  starts to press the region RB, and thus the panel  400  cracks only from the connection to the one end part  431  side, and the panel  400  does not crack from the connection to the other end part  432  side. In this case, an opening portion, the size of which is approximately half of the opening portion to be originally formed, is formed in the panel  400 . On the other hand, in the case where the panel  400  cracks from the connection to the other end part  432  side and does not cracks from the connection to the one end part  431  side at all, the tab  500  can continue to press the region RA (refer to  FIG. 3 ) without tilt or rotation as mentioned above. Thus, the panel  400  then cracks from the connection to the one end part  431  side. Even if the front end part  510  of the tab  500  presses the region  4 A toward the inside of the beverage can  100  and makes a contact with the edge of the small opening, the reaction force from the edge of the small opening is small since the panel  400  already has been cracked in the region  4 B. Thus, the tab  500  does not tilt or rotate. In this case, the opening portion to he originally formed is formed in the panel  400 . Thus, it is desirable that the cracking of the panel  400  from the connection should progress toward the other end part  432  side earlier than the one end part  431  side. 
         [0089]    By the way, the cracking of the panel  400  occurring earlier on the one end part  431  side beyond the connection can be inhibited by appropriately setting various parameters such as the shape/material of the panel  400 , the shape of the first score line  430 , the shape of the second score line  450 , and the shape/material of the tab  500 . However, the above cracking is difficult to be perfectly inhibited from occurring, and the panel  400  may crack earlier on the one end part  431  side beyond the connection, depending on the tolerances of the dimensions of units or an operation manner of a user. 
         [0090]    To avoid this, in the exemplary embodiment, even in the case where the cracking of the panel  400  occurs earlier on the one end part  431  side beyond the connection, progress of the cracking is designed to be temporarily slowed down (the progress rate of the cracking is designed to be temporarily decreased), and the operation load from the tab  500  is designed to be applied on the other end part  432  side (part included in the first score line  430  and located on the other end part  432  side beyond the connection). Hereinbelow, the design for applying the operation load from the tab  500  on the other end part  432  side will be described. 
         [0091]      FIG. 6  is an enlarged view of the connection between the first score line  430  and the second score line  450 . 
         [0092]    As shown in the figure, in the exemplary embodiment, a groove width changing portion  435  that is different in width from (increases in width in comparison with) the other portions of the first score line  430  is provided. More specifically, in the exemplary embodiment, the groove width changing portion  435  is provided in the part located on the one end part  431  side beyond. the connection in the first score line  430 . 
         [0093]    Here, the first score line  430  will be described in detail. The first score line  430  is formed by the groove as mentioned above. In the groove, a bottom surface  430 A, a first side surface  430 B connected to the bottom surface  430 A, and a second side surface  430 C also connected to the bottom surface  430 A are provided. 
         [0094]    The first side surface  430 B is located on. one side of the bottom surface  430 A in the width direction of the groove. Further, the first side surface  430 B is formed toward the upper side (upper side in the vertical direction, front side direction of the paper sheet in the figure) from the connection with the bottom surface  430 A. The second side surface  430 C is located on the other side of the bottom surface  430 A in the width direction of the groove. Further, the second side surface  430 C is formed toward the upper side from the connection with the bottom surface  430 A, similarly to the first side surface  430 B. 
         [0095]    The groove width changing portion  435  functioning as a speed decreasing unit is formed by applying a curvature to each of part of the first side surface  430 B and part of the second side surface  430 C and by outwardly expanding each of the part of the first side surface  43013  and the part of the second side surface  430 C. That is to say, in the exemplary embodiment, a concave portion is formed on each of the first side surface  430 B and the second side surface  430 C to form the groove width changing portion  435 . 
         [0096]      FIG. 7  is a cross-sectional view taken along a line VII-VII in  FIG. 6 . 
         [0097]    As described above and shown in  FIG. 7 , the first score line  430  includes the bottom surface  430 A, the first side surface  43013  extending upward from the connection with the bottom surface  430 A, and the second side surface  430 C extending upward from the connection with the bottom surface  430 A. 
         [0098]    Usually, cracking of the panel  400  along the first score line  430  may occurs at a part below the connection (corner) between the bottom surface  430 A and. the one side surface. More specifically, for example, the cracking of the panel  400  is likely to occur at the lower part below the connection between the first side surface  43013  and the bottom surface  430 A, as shown in  FIG. 7 . That is to say, cracking of the panel  400  is likely to occur at a part between the rear surface of the panel  400  and the connection between the first side surface  430 B and the bottom surface  430 A. Further, the cracking progresses along the first score line  430 . 
         [0099]    As a result, in the exemplary embodiment, in the case where the cracking of the panel  400  occurs from the connection toward the one end part  431  of the first score line  430 , sequential cracking of the panel  400  occurs in the lower part below the first side surface  430 B, and thereby cracking of the panel  400  progresses along a route shown in an arrow  6 A in  FIG. 6 , for example. 
         [0100]    If the groove width changing portion  435  is provided as described in the exemplary embodiment under the situation where such cracking may occur, the progress direction of the cracking greatly changes at a part denoted by a reference numeral  6 B in  FIG. 6 , and thus the cracking is difficult to progress. In this case, the progress rate of the cracking is temporarily decreased (delayed). Further, in this case, shearing force acting on the part (part denoted by a reference numeral  6 C) located on the upper side of the connection in the figure increases, and thereby cracking of the panel  400  is likely to occur on the other end part  432  side beyond the connection. 
         [0101]    Note that, in the exemplary embodiment, the progress direction of cracking greatly changes also in a part denoted by a reference numeral  6 D in addition to the part denoted by the reference numeral  6 B, and the situation in which cracking is difficult to progress temporarily occurs. In other words, in the exemplary embodiment, plural changing points where the progress direction greatly changes are provided, and the situation in which cracking is difficult to progress occurs at the plural changing points. In this case, the panel  400  cracks on the other end part  432  side easier than in the case where only one changing point is provided. 
         [0102]    Note that, the shape of the groove width changing portion  435  is not limited to the shape shown in  FIG. 6 , and the groove width changing portion  435  may be formed into an outer shape of a rectangle, as shown in  FIG. 8  (an enlarged view of the connection between the first score line  430  and the second score line  450 ). That is to say, although the outer shape of the groove width changing portion  435  shown in  FIG. 6  is approximately a circle, the groove width changing portion  435  shown in  FIG. 8  has the outer shape of a rectangle. 
         [0103]    More specifically, in the groove width changing portion  435  shown in  FIG. 8 , a concave portion is formed on each of the first side surface  430 B and the second side surface  430 C, similarly to the groove width changing portion  435  shown in  FIG. 6 . Here, in the concave portion formed on the first side surface  430 B, there are provided a first perpendicular surface  61  that is disposed to be perpendicular to the first side surface  430 B, a second perpendicular surface  62  that is provided to the side further from the connection than the first perpendicular surface  61  and is disposed to be perpendicular to the first side surface  430 B, and a connecting surface  63  connecting the first perpendicular surface  61  and the second perpendicular surface  62 . Note that, the second side surface  430 C side is similarly configured, and there are provided a first perpendicular surface  64 , a second perpendicular surface  65 , and a connecting surface  66 . 
         [0104]    For example, in the case where the panel  400  cracks sequentially along the first side surface  430 B at the part below the first side surface  430 B in the configuration example shown in  FIG. 8 , the progress rate of the cracking decreases firstly at a part denoted by a reference numeral  8 A (the part where the first perpendicular surface  61  is provided) in the figure. Further, the progress rate of the cracking also decreases at a part denoted by a reference numeral  8 B (the part where the second perpendicular surface  62  is provided) in the figure. In this case, similarly to the above, the shearing force acting on the other end part  432  side increases, and thereby the cracking of the panel  400  is likely to occur on the other end part  432  side beyond the connection. 
         [0105]    Further, the groove width changing portion  435  can be formed into a shape shown in  FIGS. 9A to 9H  (views illustrating other shapes of the first score line  430 ). In the configuration example shown in  FIG. 9A , the groove width changing portion  435  is formed by providing a concave portion only on the first side surface  430 B. Note that, in the configuration example, the concave portion having the outer edge shape of a triangle is formed, as shown in  FIG. 9A . However, the outer edge shape is not limited to the triangle, and may be a rectangle or a semicircle, as an example. Although the concave portion is formed on the first side surface  430 B in the configuration example, the concave portion is alternatively formed on the second side surface  430 C if there is high possibility of occurrence of cracking of the panel  400  at the part below the second side surface  430 C. 
         [0106]    As shown in  FIG. 9B , the groove width changing portion  435  may be formed by providing a convex portion on each of the first side surface  430 B and the second side surface  430 C to partially decrease the groove width. Note that, in the configuration example, the convex portion having the outer edge shape of a rectangle is formed. However, the outer edge shape may be another shape such as a semicircle, a triangle, or a trapezoid. Further, as shown in  FIG. 6C , two convex portions are provided on the first side surface  430 B and the second side surface  430 C, respectively, and the two convex portions may be different in position from each other in the direction where the first score line  430  extends. 
         [0107]    Here, the first score line  430  in the exemplary embodiment is formed by pressing a mold onto the panel  400 . In the case of the configuration example shown in  FIG. 9B , the thickness of the part fitting with the section between the one convex portion and the other convex portion in the mold becomes small, and thus the part having the small thickness is likely to be broken. In the configuration example shown in  FIG. 9C , the thickness of the part where the groove width changing portion  435  is to be formed in the mold is increased, and thus the mold is not likely to be broken in comparison with the configuration example shown in  FIG. 9B . 
         [0108]    Note that, part of the first side surface  430 B or the like is bent by forming a concave portion or a convex portion on the first side surface  430 B or the like in the aforementioned configuration, and thereby the progress rate of the cracking is delayed, although the description thereof has been omitted. However, progress of the cracking can be delayed even by the configuration where no bending part is formed, as shown in  FIG. 9D . In the configuration example shown in  FIG. 9D , each of part of the first side surface  430 B and part of the second side surface  430 C is formed to have waves, and thereby the progress route of cracking, other than a linear route, is prepared. Accordingly, the progress of the cracking is delayed. Note that the waves may be formed by connecting plural planes as shown in  FIG. 9E . 
         [0109]    In the above, there has been described the configuration in which the groove width is changed only in the groove width changing portion  435 , and the groove width is back to the original groove width on the downstream side beyond the groove width changing portion  435 . However, the changed groove width may be kept on the downstream side beyond the groove width changing portion where the groove width is changed. Specifically, the shape such as  FIG. 9F or 9G  can be formed. In each of these configuration examples, the progress rate of the cracking decreases at the part denoted by a reference numeral  9 A. 
         [0110]    The description will be given further for the configuration examples shown in  FIGS. 9F and 9G . In each of the configuration examples, a step is provided on each of the first side surface  430 B and the second side surface  430 C (at the part denoted by the reference numeral  9 A), and the progress rate of the cracking decreases at the part where the step is provided. 
         [0111]    The description will be further given for the first side surface  430 B in  FIG. 9F  as an example. A first section  9 E is provided at the part of the first side surface  430 B opposed to the second side surface  430 C. Moreover, a second section  9 F located to be closer to the second side surface  430 C is provided at a part different from the part where the first section  9 E is provided in the extending direction of the first score line  430 . In the configuration example, a step  9 G is provided between the first section  9 E and the second section  9 F. In the configuration example, in the case where cracking progresses along the first section  9 E for example, the progress rate of the cracking is temporarily delayed at the part where the step  9 G is provided. 
         [0112]    As shown in  FIG. 9H , an extending direction of the first score line  430  can he changed in the middle, to decrease the progress rate of the cracking at the part where the extending direction changes. That is to say, in the configuration example shown in  FIG. 9H , the first score line  430  is bent twice, to decrease the progress rate of the cracking of the panel  400  at each of the bending parts. 
         [0113]    In the above, the groove width changing portion  435  is provided only on the one end part  431  side beyond the connection. However, the groove width changing portion  435  may be provided on each of the one end part  431  side and, the other end part  432  side beyond the connection. However, in this case, the number of the groove width changing portions  435  on the one end part  431  side should be increased in comparison with the number of the groove width changing portions  435  on the other end part  432  side, to achieve a state where cracking is more difficult to progress on the one end part  431  side than on the other end part  432  side. 
         [0114]    With reference to  FIG. 3  again, the can lid  300  will be further described. 
         [0115]    In the exemplary embodiment, on a region between the one end part  431  and the other end part  432  of the first score line  430  (a part to become the base of the tongue part), a groove  600  is provided as shown in  FIG. 3 . This groove  600  is formed from the side where the one end part  431  is provided toward the side where the other end part  432  is provided. By this configuration, the tongue part is easily folded in the exemplary embodiment. Note that, the groove  600  is not essential, and may be omitted. The groove  600  is not limited to be straight, and may have a curve. 
         [0116]    Although the description has been given for, as one example, the case where the second score line  450  is provided to pass between the region PA and the protrusion  420  as described above in the exemplary embodiment, the arrangement configuration of the second. score line  450  is not limited to the above configuration. For example, as shown in  FIG. 10  (a view illustrating another configuration example of the can lid  300 ), the second score line  450  that does not pass between the region RA and the protrusion  420  may be provided. In addition, the shape of the second score line  450  is not particularly limited, and the second score line  450  may curve. 
         [0117]    In the exemplary embodiment, the one end part  431  and the other end part  432  of the first score line  430  inward curl toward the inside of the region surrounded by the first score line  430  as shown in the  FIG. 3 . Thus, the first score line  430  comes closer to the center line CL of the tab  500 , toward the terminal end of the first score line  430 . 
         [0118]    Here, in the exemplary embodiment, cracking of the panel  400  occurs toward the one end part  431  and the other end part  432  of the first score line  430  as described above. However, if each of the one end part  431  and the other end part  432  of the first score line  430  curls, the progress direction in the first score line  430  greatly changes at the one end part  431  and the other end part  432 . in this case, the cracking of the panel  400  stops at the one end part  431  and the other end part  432 . 
         [0119]    For example, as shown in  FIG. 11  (a view illustrating still another configuration example of the can lid  300 ), if the one end part  431  and the other end part  432  have no curl and are formed to be straight, the cracking of the panel  400  is likely to occur at the part beyond each of the one end part  431  and the other end part  432  (the part on the extension line of the first score line  430 , the part where cracking is not planned). 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100  . . . Beverage can 
           200  . . . Container body (can body) 
           300  . . . Can lid 
           400  . . . Panel 
           430  . . . First score line 
           430 A . . . Bottom surface 
           430 B . . . First side surface 
           430 C . . . Second side surface 
           435  . . . Groove width changing portion 
           450  . . . Second score line