Patent Publication Number: US-2023150722-A1

Title: Can lid opening tab, can lid, method for manufacturing can lid opening tab

Description:
TECHNICAL FIELD 
     The present invention relates to a can lid opening tab, a can lid including the can lid opening tab, and a method for manufacturing a can lid opening tab. 
     BACKGROUND ART 
     A can lid including an opening tab of a stay-on type tab is generally known. Such a can lid is configured such that a tab is fixed at the panel of a can lid body. The tab includes a fixing part to be fixed to the can lid body by a rivet, a pulling-up part separated from the fixing part by a slit, and to be pulled up by fingers, and a pressing-down part to be pressed down in response to pulling up of the pulling-up part with the fixing part as a fulcrum. For such a can lid including the tab, the pressing-down part of the tab ruptures the score formed at the panel of the can lid body, so that the opening piece sectioned by the score is retracted into the inside of the can, thereby opening the can lid. 
     Such an opening tab in the can lid reduces the force to be applied on the fingers for the opening operation using the principle of the lever with the fixing part as the fulcrum, the pulling-up part as the point of effort, and the pressing-down part as the point of load. The length from the fixing part to the pulling-up part is longer than the length from the fixing part to the pressing-down part. 
     For such an opening tab, display information such as a two-dimensional code is provided at the portion from the fixing part to the pulling-up part formed relatively long. At this step, when the display information is provided on the back face side of the tab facing the can lid body, it is configured such that the display information is hidden until the can lid is opened, and only the purchaser of a can product can access the display information by pulling up the pulling-up part of the tab for opening the can lid (refer to PTL 1). 
     CITATION LIST 
     Patent Literature 
     
         
         [PTL 1] Japanese Patent Application Publication No. 2019-104531 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     The can lid opening tab is required to be ensured in rigidity along the longitudinal direction so that the pressing-down part is pressed down with reliability in synchronization with pulling up of the pulling-up part. To this end, a curling part is formed at a periphery of the tab, and reinforcing concavo-convex processing is performed between the pulling-up part and the fixing part. 
     At this step, when downward convex processing is tried to be performed, the convex processing causes the back face of the tab to approach the surface of the lid main body. For this reason, in order to avoid the contact of the back face of the tab with the surface of the lid main body, the precision of processing is required to be adjusted exactly, undesirably resulting in a complicated production process. 
     Further, in the case where reinforcing concavo-convex processing is performed on between the pulling-up part and the fixing part, when the marking position of the display information is deviated from the central position, or information is marked widely inside the curling part, a part of the display information may lie on the step portion resulting from concavo-convex processing. Thus, the step causes distortion in the display, undesirably making it impossible to obtain favorable visibility of the display information. 
     It is an object of the present invention to cope with such a problem. Namely, it is an object of the present invention to eliminate the necessity of reinforcing concavo-convex processing requiring an exact processing precision while ensuring the rigidity in the longitudinal direction of the tab itself, thereby simplifying the production process; to enable ensuring of the favorable display visibility even when misplacement of display is caused, or display is performed widely inside the curling part, or the like. 
     Solution to Problem 
     In order to solve such problems, the present invention includes the following configuration. 
     A can lid opening tab, includes: a pulling-up part provided on one end side in a longitudinal direction; a pressing-down part provided on another end side in the longitudinal direction; a fixing part provided between the pulling-up part and the pressing-down part, and sectioned and formed by a U-shaped slot, and to be fixed on a can lid body; and a curling part formed continuously on a circumference except for a connecting piece cutting trace provided at the pressing-down part. The can lid opening tab is characterized in that a step-less unprocessed deflection face with a periphery surrounded without disconnection by the curling part is provided between the fixing part and the pulling-up part, and a display part is provided on at least one face side of the deflection face. 
     Advantageous Effects of Invention 
     With the can lid opening tab having such features, it is possible to eliminate the necessity of reinforcing concavo-convex processing requiring adjustment of an exact processing precision while ensuring rigidity in the longitudinal direction of the tab itself. This can simplify the production process. Further, with the can lid opening tab having such features, it is possible to ensure favorable display visibility even when misplacement of display is caused, or display is performed widely inside the curling part. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an explanatory view showing a can lid opening tab in accordance with an embodiment of the present invention ( FIG.  1    at (a) is an A-Across sectional view,  FIG.  1    at (b) is a plan view, and  FIG.  1    at (c) is a back view)). 
         FIG.  2    is an explanatory view showing a method for manufacturing the can lid opening tab in accordance with the embodiment of the present invention, and a can lid on which the can lid opening tab is mounted. 
         FIG.  3    is an explanatory view in a back view showing a forming process of the can lid opening tab ( FIG.  3    at (a) a state after marking of a display part,  FIG.  3    at (b) a state after hole processing, and  FIG.  3    at (c) a state after stamping of a periphery). 
         FIG.  4    is an explanatory view in a back view showing a forming process of a can lid opening tab ( FIG.  4    at (a) a state after processing of the inside of the periphery, and shaping processing of a fixing part,  FIG.  4    at (b) a state after a bend process of the periphery, and  FIG.  4    at (c) a state after a curl process of the periphery). 
         FIG.  5    is an explanatory view showing movement of a processing tool of the curl process ( FIG.  5    at (a) before the process, and  FIG.  5    at (b) after the process). 
         FIG.  6    is an explanatory view showing another example of the processing tool of the curl process. 
         FIG.  7    is an explanatory view of an example ( FIG.  7    at (a) is a plan view, and  FIG.  7    at (b) is a B-B cross sectional view). 
         FIG.  8    is an explanatory view of an example (an A-A cross sectional view in  FIG.  7    at (a)). 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Below, referring to the accompanying drawings, embodiments of the present invention will be described. In the following description, the same reference numerals and signs indicate portions having the same function, and repetitive description referring to the drawings will be appropriately omitted. The arrow X direction in  FIG.  1    shows a longitudinal direction of a can lid opening tab, the arrow Y direction shows a direction (width direction) orthogonal to the X direction in a plan view, and the arrow Z direction shows a thickness direction of the can lid opening tab. 
     As shown in  FIG.  1   , the can lid opening tab (below, tab)  1  is provided with a pulling-up part  2  on one end side in the longitudinal direction (the X direction shown), a pressing-down part  3  on the other end side in the longitudinal direction (the X direction shown), and a fixing part  4  between the pulling-up part  2  and the pressing-down part  3 . 
     The pulling-up part  2  is a portion on which fingers of a person performing an opening operation are put, and is pulled up in the Z direction shown, thereby performing the opening operation. The pressing-down part  3  is a portion to be pressed down in the opposite direction by pulling up of the pulling-up part  2 . This portion comes in contact with a panel of a can lid body, and is pressed down, resulting in rupture of a score of the can lid body. 
     The fixing part  4  is sectioned and formed by a U-shaped slot  5 , and includes a rivet hole  6  into which a rivet to be provided on the panel of the can lid body is inserted. The rivet to be provided on the panel of the can lid body is inserted into the rivet hole  6 , and is crimped, so that the fixing part  4  is fixed to the can lid body. 
     At the center of the pressing-down part  3 , there is a connecting piece cutting trace  7 . Then, a curling part  8  is formed at a circumference edge of the tab  1  except for the connecting piece cutting trace  7 . The curling part  8  enhances bending rigidity along the longitudinal direction of the tab  1  in order for the tab  1  to function as a lever with the pulling-up part  2  as the point of effort, the fixing part  4  as the fulcrum, and the pressing-down part  3  as the point of load. 
     At this step, at a position at which the connecting piece cutting trace  7  is present, disconnection cannot avoid being caused in the curling part  8 . However, the provision of the connecting piece cutting trace  7  in the pressing-down part  3  can set the disconnected part of the curling part  8  at the position not to be applied with a bending force when the pulling-up part  2  is pulled up for the opening operation. 
     The tab  1  is provided with a shaping part  10  convex opposite to the Z direction at a periphery of the fixing part  4 . Then, a step-less unprocessed deflection face  20  is formed at a portion between the fixing part  4  and the pulling-up part  2 , a portion outside the shaping part  10 . The deflection face  20  is not subjected to concavo-convex processing by a processing tool at the portion itself, and a downwardly convex deflection face  20  is formed when the curling part  8  at the periphery thereof is formed. 
     The back face  21  facing the can lid body of the deflection face  20  is provided with a display part P. The back face  21  provided with the display part P is surrounded without disconnection at the periphery thereof by the curling part  8 , and an uniform face without a step is formed inside the curling part  8  and outside the shaping part  10 . For this reason, the display part P will not be deteriorated in visibility due to a concavo-convex step even when a marking position is a little deviated from the center, and will not be deteriorated in visibility even when the display part P is provided widely inside the curling part  8 . Incidentally, herein, the example is shown in which the display part P is provided on the back face  21  of the deflection face  20 . However, the display part P may be provided on the front face side of the deflection face  20 , and may be provided on both the front and back faces thereof. 
     Further, the deflection face  20  enhances the bending rigidity in the longitudinal direction of the tab  1  by deflection of itself. For this reason, even when the portion between the fixing part  4  and the pulling-up part  2  is not subjected to concavo-convex processing by a processing tool, the tab  1  has bending rigidity enough to function as a lever with the puffing-up part  2  as the point of effort, the fixing part  4  as the fulcrum, and the pressing-down part  3  as the point of load. 
     The deflection face  20  of the tab  1  has a smooth deflection shape in which the amount of deflection is maximum at a point closer to the fixing part  4  side than to the center from the circumference in the deflection along the X direction (longitudinal direction) of  FIG.  1   . The maximum amount of deflection at the deflection face  20  is preferably 0.2 mm or more. By assuming a smooth deflection shape in which the position of the maximum amount of deflection of the deflection face  20  is set closer to the fixing part  4 , the cross-sectional two-dimensional moment is increased, which enables an increase in rigidity of the tab  1 . Further, by setting the position of the maximum deflection of deflection along the X direction closer to the fixing part  4 , it is possible to sufficiently ensure the gap for fingers to be put under the pulling-up part  2  for opening upon mounting the tab  1  at the can lid. 
     The display part P is a drawing part drawn by, for example, laser marking or ink jet printing, on which a two-dimensional code, a logotype, a picture, a letter, a number, or the like is drawn. After drawing of the display part P, a processing tool will not impinge on the display part P. For this reason, the shape of the tab  1  will not disturb the visibility of the display part P. Incidentally, when the display part P is formed by laser marking, a colored painted surface is formed on the surface of the tab  1 . 
     The tab  1  and the can lid to which it is mounted are manufactured as shown in  FIG.  2   . Namely, a tab material T rewound from a coil C is, first, passed through a drawing device (e.g., a laser marker)  30 , so that the display part P drawn by laser marking or the like is formed on the back face of the tab material T. Then, the tab material T including the display part P formed thereon is passed through a tab shaping machine  31 , resulting in the formation of the tab  1 . 
       FIGS.  3  and  4    each show the tab forming process during which the tab material T passes through between the drawing device  30  and the tab shaping machine  31 .  FIG.  3    at (a) shows a state in which the display part P is drawn on one face side (back face side) of the long tab material T. The display part P is formed in the drawing device  30  shown in  FIG.  2   .  FIG.  3    at (b) shows a state in which the tab material T is subjected to hole processing in the tab shaping machine  31 . Herein, a pair of holes T 1  and T 2  for forming a connecting piece (carry point) T 3  extending in the longitudinal direction are formed at a position away from the display part P in the longitudinal direction of the tab material T, and the U-shaped slot  5  and the rivet hole  6  for sectioning and forming the fixing part  4  are formed between the display part P and the connecting piece T 3 . In  FIG.  3    at (c), a cut line T 4  for connecting the pair of holes T 1  and T 2 , and defining the further outer side of the circumference edge of the tab is formed by stamping. 
       FIG.  4    at (a) shows a state in which the inside of the cut line T 4  is processed, and the shaping part  10  is formed near the rivet hole  6  and the slot  5 .  FIG.  4    at (b) shows a state after bend processing the inside of the cut line T 4  along the circumference shape of the tab  1 .  FIG.  4    at (c) shows a state in which a bent piece T 5  formed by bend processing is curl processed, thereby forming the curling part  8 . 
     In curling of curl processing the bent piece T 5  formed by bend process, and forming the curling part  8  at the periphery of the tab except for the connecting piece T 3 , as shown in  FIG.  5   , a lower tool  12  having a die part  12 A for subjecting the bent piece T 5  to curl shaping, and an upper tool  11  for pressing the tab material T against the lower tool  12  are used. As shown in  FIG.  5    at (a), the tab material T subjected to bend processing is arranged between the upper tool  11  and the lower tool  12 . As shown in  FIG.  5    at (b), the upper tool  11  and the lower tool  12  are made closer to each other, so that the bent piece T 5  of the tab material T is pressed against the die part  12 A of the lower tool  12 , resulting in the formation of the curling part  8 . 
     At this step, the lower tool  12  has an opening part  12 B for making the display part P unprocessed. The opening part  12 B is provided inside the die part  12 A. The positioning of the display part P inside the opening part  12 B prevents a processing tool (the upper tool  11  and the lower tool  12 ) from impinging on the portion at which the display part P is formed. Then, the provision of the opening part  12 B at the lower tool  12  results in the formation of the downwardly convex deflection face  20  at the portion including the display part P provided thereon when the curling part  8  is formed. 
     The opening part  12 B may be set in an opened state as shown in  FIG.  5   , or may be provided with a movable support member  12 C as shown in  FIG.  6   . The movable support member  12 C descends according to the curve deformation of the tab material T including the display part P formed thereon when the deflection face  20  is formed in the opening part  12 B. The movable support member  12 C supports the deflection face  20  from the back face side, thereby performing control so as to prevent the deformation of the deflection face  20  from being excessively caused. 
     The movable support member  12 C is supported by, for example, a spring, and is movable with the formation of the deflection face  20 . For this reason, even when the display part P impinges on the movable support member  12 C, the display will not be broken. Further, the movable support member  12 C may include an elastic member such as rubber or resin. 
     The tab material T which has passed through a tab shaping machine  31  is fed with the tab  1  connected to the tab material T by the connecting piece T 3  as shown in  FIG.  4    at (c), to a conversion press  32  shown in  FIG.  2   . With the conversion press  32 , shaping of the can lid body is performed, and the rivet hole  6  of the tab  1  is positioned with respect to the rivet position of the can lid body. Then, the connecting piece T 3  is cut, and the tab  1  is separated from the tab material T, and the rivet is inserted into the rivet hole  6 , and is crimped. Thus, the tab  1  is mounted on the can lid body. This results in a can lid W including the tab  1 , and the can lid body to which the fixing part  4  of the tab  1  is fixed, and which has a score to be ruptured by pressing down of the pressing-down part  3 . 
     Thus, the tab  1  in accordance with the embodiment of the present invention is configured as follows: the display part P is formed on the back face  21  facing the can lid body, so that display information is hidden until the can lid is opened, and only a purchaser of a can product can access the display information by pulling up the pulling-up part  2  of the tab  1  for opening the can lid. As a result of this, it is possible to use the display part P as a prize, a lot, or the like. Then, in that case, the curling part  8  without disconnection is formed at the periphery of the display part P. In addition, the display part P is provided on the back face  21  of the unprocessed deflection face  20 . As a result, sufficient bending rigidity along the longitudinal direction of the tab  1  is ensured. 
     Then, the back face  21  of the deflection face  20  on which the display part P is formed is made unprocessed. This eliminates the necessity of the adjustment of the exact processing precision, which can simplify the production process. Further, there is no step resulting from concavo-convex processing on the deflection face  20  on which the display part P is formed. For this reason, it is possible to ensure favorable display visibility even when misplacement of display is caused, or display is performed widely inside the curling part  8 . 
     EXAMPLE 
     As shown in  FIG.  7   , for each tab  1  (each of samples 1 to 5) having the deflection face  20  with an X direction width m=10 mm, and a Y direction width n=14.4 mm, the amounts of deflection relative to the circumference were measured at seven sites of (1) to (7) of  FIG.  7    at (b) along the Y direction, in cross section (B-B cross section) at the position closer to the fixing part  4  from the center at an X direction width m, namely, the position resulting in (mt/m)&gt;½. Of the (1) to (7), (1) and (7) are the points on the circumference, and (2) to (6) are the points sectioning the Y direction width n at equal intervals. The site of (4) is the vicinity of the center in the Y direction of the deflection face  20 . 
     Further, at respective points of (8), (9), (10), (4), (11), and (12) of  FIG.  8    along the X direction ((4) is the same as the position in  FIG.  7    at (b)) in the cross section (A-A cross section) of the center in the Y direction width n, the amounts of deflection with respect to the circumference were measured. 
     The measurement value of the amount of deflection at each site in each sample, the measurement values of the tab breaking strength (N) and the tab breaking angle (deg) in each sample, the tab breaking strength evaluation, the tab breaking angle evaluation, the visibility evaluation, and the comprehensive evaluation are shown in Table 1. 
     The tab breaking strength herein denotes the force applied on the pulling-up part  2  immediately before breaking of the tab  1  upon mounting the tab  1  on the lid without a score, and raising the tab  1 . The tab breaking angle denotes the angle formed between the tab  1  and the lid at the time of occurrence of tab breaking upon mounting the tab  1  on the lid without a score, and raising the tab  1 . Each sample includes five individuals similarly shaped, and the numerical value of the table is the average value of the measurement values for each of the five individuals. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Sample 5 
                 Sample 4 
                 Sample 3 
                 Sample 2 
                 Sample 1 
                 Measurement site 
                   
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 (1) 
                 Amount of deflection 
               
               
                 0.10 
                 0.12 
                 0.16 
                 0.17 
                 0.36 
                 (2) 
                 [mm] 
               
               
                 0.16 
                 0.21 
                 0.22 
                 0.28 
                 0.58 
                 (3) 
                   
               
               
                 0.19 
                 0.22 
                 0.25 
                 0.31 
                 0.67 
                 (4) 
                   
               
               
                 0.16 
                 0.20 
                 0.21 
                 0.28 
                 0.59 
                 (5) 
                   
               
               
                 0.08 
                 0.12 
                 0.16 
                 0.18 
                 0.37 
                 (0) 
                   
               
               
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 0.00 
                 (7) 
                   
               
               
                 0.11 
                 0.11 
                 0.12 
                 0.16 
                 0.20 
                 (8) 
                   
               
               
                 0.14 
                 0.14 
                 0.20 
                 0.24 
                 0.29 
                 (9) 
                   
               
               
                 0.16 
                 0.16 
                 0.24 
                 0.28 
                 0.38 
                 (10)  
                   
               
               
                 0.16 
                 0.16 
                 0.23 
                 0.27 
                 0.36 
                 (11)  
                   
               
               
                 0.13 
                 0.14 
                 0.16 
                 0.18 
                 0.24 
                 (12)  
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 30.62 
                 30.88 
                 31.78 
                 31.94 
                 31.10 
                 Tab breaking strength [N] 
               
               
                 69.84 
                 72.96 
                 78.04 
                 85.44 
                 70.84 
                 Tab breaking angle [deg] 
               
               
                 BB 
                 BB 
                 AA 
                 AA 
                 AA 
                 Tab breaking strength evaluation 
               
               
                 CC 
                 BB 
                 BB 
                 AA 
                 BB 
                 Tab breaking angle evaluation 
               
               
                 AA 
                 AA 
                 AA 
                 AA 
                 BB 
                 Visibility evaluation 
               
               
                 CC 
                 BB 
                 BB 
                 AA 
                 BB 
                 Comprehensive evaluation 
               
               
                   
               
            
           
         
       
     
     Herein, the evaluation of the tab breaking strength is conducted as follows: 30 N or more is rated as BB, and 31 N or more is rated as AA. The evaluation of the tab breaking angle is conducted as follows: less than 70° is rated as CC, 70° or more is rated as BB, and 80° or more is rated as AA. 
     Further, as the visibility evaluation, whether the distortion of the pattern (or the code) on the deflection face  20  of the tab  1  has occurred, or not is evaluated. The one which has not undergone the occurrence of distortion is rated as AA, and the one which has hardly undergone the occurrence of distortion is rated as BB. 
     In the Example, by setting the maximum amount of deflection (the amount of deflection of the measurement site (4)) of the deflection face  20  in the tab  1  at 0.2 mm or more, favorable evaluations are obtained in terms of both aspects of the tab breaking strength and the tab breaking angle. In consideration of the visibility evaluation, even when the maximum amount of deflection is larger than 0.4 mm (0.67 mm), the visibility can be ensured. However, when the maximum amount of deflection is set at 0.4 mm (0.31 mm) or less, the visibility is further improved. Therefore, in the comprehensive evaluation, it could be confirmed that the sample 2 is particularly good, and, when importance is placed on the visibility, the samples 2, 3, and 4 are particularly good. 
     Up to this point, the embodiments of the present invention have been described in details by reference to the accompanying drawings. However, the specific configuration is not limited to the embodiments, and the present invention includes even the changes of the design within the scope not departing from the gist of the present invention, or the like. Further, the respective embodiments can be combined by using mutual technologies so long as there is no particular contradiction or problem in the object and configuration thereof, and the like. 
     REFERENCE SIGNS LIST 
     
         
           1  Can lid opening tab (tab) 
           2  Pulling-up part 
           3  Pressing-down part 
           4  Fixing part 
           5  Slot 
           6  Rivet hole 
           7  Connecting piece cutting trace 
           8  Curling part 
           10  Shaping part 
           11  Upper tool 
           12  Lower tool 
           20  Deflection face 
           21  Back face 
           30  Drawing device 
           31  Tab shaping machine 
           32  Conversion press 
         T Tab material 
         P Display part 
         T 1 , T 2  Hole 
         T 3  Connecting piece 
         T 4  Cut line 
         T 5  Bent piece 
         W Can lid