JP4422012B2 - Can lid with open tab and method for producing the same - Google Patents

Description

  The present invention relates to a can lid with a tab for opening an open can of an easy open can such as a beverage can and a can, and a method for producing the same, and more specifically, an opening tab for a can lid of a metal can such as an aluminum can and a steel can. This relates to improvements in rotation prevention technology.

  In a metal easy open beverage can, etc., a score line called a score line is provided in an endless or notched ring surrounding a part or all of the top plate portion of the can lid, and the inside of the score line is opened. As a lid for the can area, a can opening tab is attached in a corresponding arrangement. Then, by pulling up one end on the operation side of the tab, the lid piece is pushed down by the pressing portion on the other end side to cause breakage in the incision line. In the case of a full-open type, the lid can be opened by removing all of the lid pieces together with the tabs.

  In many cases, the tab for opening the can lid for such an easy-open can is formed by punching a rivet integrally formed on the top plate surface of the can lid body into a rivet hole provided in the tab, and from above. It is attached at a predetermined position on the top plate surface by caulking. The rivet and rivet hole are generally circular. For this reason, the tab may cause a rotational displacement about the axis of the rivet. On the other hand, since the tab for opening can break the cut line using the principle of the lever as described above, the cut line defining the direction of the tab and the lid piece of the open area Therefore, it is necessary to correctly maintain the relative positional relationship within a narrow range determined by design. Nevertheless, the tab may be rotationally displaced by vibrations or some external force applied during the handling process of the can lid itself, the transporting process of the beverage can, or the dispensing process in the vending machine. If the rotational displacement exceeds the allowable range, the can opening operation becomes difficult, and there is a possibility that the tab may come off due to a severe tab operation and the can cannot be opened.

The inconvenience due to such an unintentional rotational displacement of the tab has been recognized for a long time, and conventionally, as a tab detent technique for avoiding such inconvenience, it is disclosed in Patent Documents 1 and 2 below. Proposals have been made.
Japanese Patent Publication No.51-3260 Japanese Patent Laid-Open No. 8-26275 proposes a technique in which a plurality of dents are provided in a radial arrangement on the upper surface around a circular rivet hole of a tab by a punch for engraving, and when the rivet is caulked, The tab is prevented from rotating as a part of the lower surface of the top portion is bitten into the recess.

  However, in the prior art proposed in Patent Document 1, the thickness of the material constituting the tab is generally very thin, about 0.3 to 0.5 mm. Even if the above-mentioned dent is formed with a stamping punch, the depth of the dent is only extremely shallow.

  In addition, both side edges of the recess are formed into curved surfaces. For this reason, even if a part of the lower surface of the top of the rivet is bitten, it is difficult to achieve a sufficient anti-rotation effect. Attempting to form deep dents may cause harmful deformation of the tabs. In addition, in order to engage a part of the lower surface of the top of the rivet into the recess, it is necessary to apply a considerably large pressure when the rivet is caulked, without causing harmful deformation of the tab. It is practically difficult to realize this.

  The prior proposed technique of Patent Document 2 is proposed with the intention of solving such problems. This proposed technique is a burr-like shape generated by the crushed material moving radially inward to the upper edge of the rivet hole by partially crushing the peripheral edge of the rivet hole of the tab from the upper surface. A plurality of inward protrusions having a sharp tip shape are formed, and the protrusions are pierced into the shaft portion of the rivet by utilizing the plastic deformation in the diameter increasing direction of the rivet generated when the rivet is caulked. One thing to do is to prevent the tab from rotating.

  However, in this proposed technique, it is somewhat difficult to form an inward projection having a sufficient strength for realizing the anti-rotation effect by crushing itself because of the thinness of the tab material. On the contrary, the inner protrusion is crushed by the outer peripheral surface of the rivet, and the frictional force is reduced due to the reduction of the contact area. As a result, the effect of preventing the rotation of the tab may be rather lowered. Furthermore, when the inward projection is formed to have sufficient strength, the tip of the rivet is generally hollow due to the bite of the tip protruding into the peripheral wall of the hollow rivet. There is a risk that the shaft peripheral wall will be damaged, the strength thereof will be lowered, and a through hole will be seriously produced, which will impair the sealing and pressure resistance of the can.

  Because of the various problems as described above, the prior proposal techniques as shown in Patent Documents 1 and 2 are hardly actually used.

  In view of the various problems of the prior art as described above, the present invention solves these problems, and does not require any special additional process in the conventional process in the production of a tabbed can lid. It is an object of the present invention to provide a structure of a can lid with a tab and a method of manufacturing the same, which can maintain the properties and can more reliably realize the effect of preventing the rotation of the tab.

  The present invention provides the following means for solving the above problems.

  The first of the present invention relates to the structure of a can lid with a tab.

Thus, the can lid with a tab for opening the can according to the present invention has a tab for opening the can attached to the top plate surface of the can lid main body by riveting corresponding to the lid piece defined by the cut line. In the can lid,
In the circular rivet hole of the tab, one or a plurality of locking recesses extending substantially obliquely outward from the upper part of the inner peripheral surface to the peripheral part of the upper surface side hole are formed.
A locking convex portion projecting outward from the upper outer peripheral surface of the shaft portion of the rivet integrally formed with the can lid main body is engaged with the concave portion in a biting state.

  It is desirable that the bottom surface of the concave recess for locking is formed in a sag-like curved surface that is curved inward of the rivet hole.

  Further, it is desirable that the locking recesses are arranged at an equal interval in the range of 3 to 10, more preferably in the range of 4 to 8 in the direction around the rivet hole.

  A second aspect of the present invention relates to a method for manufacturing a can lid with a tab as described above.

That is, the manufacturing method of a can lid with a tab according to the present invention is a can lid in which a can opening tab is attached by riveting on a top plate surface of a can lid body corresponding to a lid piece defined by a cut line. In the manufacturing method,
The rivet hole of the tab is formed by punching using a punch for punching having one or a plurality of cutouts on the peripheral edge of the lower surface. By this punching process, the circular rivet hole is formed from the upper part of the inner peripheral surface. Forming one or a plurality of locking recesses inclined substantially diagonally outwardly from the peripheral edge of the upper surface side hole;
By inserting a rivet protruding from the top plate surface of the can lid body into the rivet hole and caulking from above, the locking convex portion protruding from the outer peripheral surface of the rivet shaft bites into the locking concave portion. It is characterized by being engaged with the state.

  The notch of the punch is a notch in the form of a concave groove in which the bottom surface is inclined obliquely upward from the middle portion of the radial line of the lower surface of the punch to the outer peripheral surface of the lower end, and the inclination angle of the bottom surface is It is desirable that the angle is set in the range of 10 to 30 °, more preferably in the range of 15 to 25 ° with respect to the plane on which the punch lower surface exists.

  Moreover, it is desirable that the notch of the punch has a height on the outer peripheral surface of the punch set to 0.3 to 1.0 times the thickness of the tab material.

  Furthermore, it is desirable that the notch portions of the punch are provided at equal intervals in the circumferential direction in the range of 3 to 10, more preferably 4 to 8.

  The can lid with a tab for opening a can according to the present invention has a rivet formed in the tab inserted into a rivet protruding from the can lid main body side, and presses the rivet from above to crimp the tab. In this case, a plastic deformation force in the diameter expanding direction is applied to the upper end portion of the shaft portion of the rivet. Moreover, this plastic deformation force acts greatly as it reaches the upper end of the shaft portion of the rivet. Corresponding to this, the rivet hole of the tab is formed with a recessed portion extending obliquely outwardly toward the peripheral edge of the hole on the upper surface side at the upper portion of the inner peripheral surface thereof, so that the shaft portion of the rivet is formed. A part of the material surely enters the concave portion, and forms a locking convex portion protruding outward from the shaft portion to firmly engage with the concave portion. Therefore, it is not necessary to apply a particularly large pressing force when rivets are caulked, and it is possible to achieve a reliable detent effect of the tabs by carrying out a normal caulking process. That the recessed portion extends obliquely outward from the upper inner peripheral surface of the rivet hole to the hole peripheral portion on the upper surface side corresponds to the plastic deformation force applied to the shaft portion when the rivet is caulked, It is possible to realize a reliable engagement relationship between the locking protrusion and the recessed portion.

  In particular, when the deep bottom surface of the recessed portion is formed in a sag-like curved surface that is curved inward of the rivet hole, the locking projections have bitten into the fully filled state without a gap. It tends to be a thing. For this reason, it is possible to realize an even more reliable detent effect of the tab.

  Further, the engaging recesses are formed at equal intervals in the range of 3 to 10 in the circumferential direction of the rivet hole, so that the engagement relationship by the engagement between the shaft part of the rivet and the recessed part is within a preferable range. Therefore, the effect of preventing the rotation of the tab can be reliably achieved.

  On the other hand, in the method for manufacturing a can lid with a tab for opening a can according to the present invention, the formation of a rivet hole that achieves the effect of preventing the rotation of the tab as described above can be performed simultaneously with the punching process of the rivet hole by a punch. Therefore, as in the case of the above-mentioned prior proposal technique, after forming the rivet hole, a radial recess is further formed on the peripheral edge of the hole with a stamping punch, or a crushing process is added to form the inward projection. It is not necessary to add another process such as forming.

  Moreover, the rivet caulking operation can also be performed with a normal pressure sufficient to crush the top end of the rivet to form the locking head. Therefore, it is possible to manufacture a can lid with a tab having a reliable function of preventing the rotation of the tab without changing the man-hours and conditions of the conventional manufacturing process.

  The notch of the punch has a deep bottom inclined obliquely upward from the middle of the radial line of the lower surface of the punch to the outer peripheral surface of the lower end, and the inclination angle is set within a range of 10 to 30 ° When this is done, it is possible to form a concave recess for locking having a good depth and a deep bottom shape on the inner peripheral surface of the rivet hole, so that the anti-rotation effect of the tab can be realized more reliably. It can be done.

  In addition, by setting the height of the notch on the outer peripheral surface of the punch within a range of 0.3 to 1.0 times the thickness of the tab material, the rivet hole of the tab has a good anti-rotation effect. A locking recess of the form can be formed.

  The technical significance of setting the number of punch notches to 3 to 10 is the same as the above-described effect based on the number of locking recesses formed thereby.

  Next, a preferred embodiment of the present invention will be described.

  FIG. 1 shows an application example of the present invention for a can lid with a tab of a steion tab type.

  This can lid (1) is mainly made of aluminum for beverage cans such as beer cans.

  The can lid (1) has a substantially flat top plate portion (3) in a can lid main body (2) attached to an opening of a can barrel (not shown) manufactured separately. The top plate portion (3) is provided with a substantially U-shaped cut line (4) at an appropriate position, and an inner area defined by the cut line (4) is a lid piece (5) as a can open area. Has been made.

  On the surface of the top plate portion (3) of the can lid main body (2), a can lid tab (6) is provided under an arrangement relationship corresponding to the lid piece (5). The tab (6) has one end as an operation end (6a) and the other end as a pressing end (6b) against the lid piece (5). It is attached to the can lid body (2) by riveting the position near the part.

  As shown in FIG. 2, a hollow cylindrical rivet (7) formed integrally by punching upward from the top plate (3) of the can lid body (2) is pre-drilled in the tab (6). This is carried out by inserting the formed round rivet hole (8) and caulking the rivet (7) by applying pressure from above. In addition, in FIGS. 1 and 2, (7a) is the top of the rivet (7) whose diameter is enlarged, (9) is the finger hook hole of the tab (6), and (10) is the triggering operation of the tab (6). Therefore, it is a semicircular arc-shaped through hole formed at a position around the rivet hole (8) of the tab.

  The above configuration is equivalent to a conventional can lid with a tab, and the operation side end portion (6a) of the tab (6) is caused by a fingertip, whereby a lid piece (5 ) To the inside of the can, thereby causing the cut line (4) to break, and then the lid piece (5) is further folded inward to open the can.

  The present invention is characterized by the structure of the riveting portion of the tab (6) and its manufacturing process. In other words, the rivet hole (8) has the main features of the punching formation, specifically, the special configuration of the punch used for punching and the special shape of the rivet hole (8) formed thereby.

  An example of the special punch (11) for punching formation of the rivet hole (8) used in the present invention is shown in FIG. The punch (11) has a lower peripheral edge (11a) as a circular shearing blade corresponding to the hole diameter of the rivet hole (8), and has a plurality of notches (12) at the lower peripheral edge.

  The notch (12) has a U-shaped concave groove shape in which the bottom surface (12a) is inclined obliquely upward from the middle of the radial line of the lower surface (13) of the punch (11) to the lower end of the outer peripheral surface. It is formed.

  When the punching process of the rivet hole (8) of the tab (6) is performed using the punch (11), first, from the state before the process shown in FIG. When the lower end of the punch (11) enters from the upper surface of the material of the tab (6), shearing is started on the tab material by the lower end periphery (11a) of the punch (11) as shown on the left side of the figure. On the other hand, at the portion where the notch (12) exists, as shown on the right side of the figure, a part of the tab material is pushed downward along the back bottom surface of the notch (12). Produces a curved deformation part (16). When the punch (11) is further pushed in, as shown in FIG. 6 (c), when the lower end of the punch (11) reaches the surface of the die (15), the lower end periphery (11a) of the punch (11) is formed. While the tab material is cut at the corresponding portion, at the portion where the notch (12) exists, the tab material is further drawn downward by the bottom surface (12a), and the upper edge of the notch (12) But shearing begins. When the punch (11) eventually reaches the position after punching is completed, the tab material is cut in the entire peripheral area of the punch (11) as shown in FIG. 4 (d), and a rivet hole (8) is formed here. .

  The rivet hole (8) formed in this way is basically circular as shown in FIG. 5 (a), but at the corresponding portion of the notch (12) of the punch (11), It has a plurality of locking recesses (14) in the direction. This recessed part (14) originates from the said deformation | transformation part (16) produced by the notch part (12) at the time of a punching process, and is located in the internal peripheral surface of a rivet hole (8), and from this internal peripheral surface upper part The bottom surface (14a) is inclined obliquely outwardly toward the hole peripheral edge on the upper surface side. More specifically, the back bottom surface (14a) is formed into a sag-like curved surface curved inward of the rivet hole (8). Accordingly, when the rivet hole (8) is observed from the upper surface side of the tab (6), the upper surface side periphery is formed around the edge of the circular hole as shown in FIG. While the arrangement is observed to protrude outward, on the lower surface side, the peripheral edge is observed as a complete circle as shown in FIG.

  In manufacturing the can lid with tabs (1), a hollow circle formed by punching in advance on the top plate surface of the can lid body (2) by preparing the tab (6) having the rivet holes (8) described above. A columnar rivet (7) is inserted through the rivet hole (8) to set the tab (6). Next, by crimping the rivet (7) from above, the top of the rivet is flattened to form a large-diameter head (7a), and the attachment of the tab is completed.

  Here, in the rivet caulking step, when pressure is applied to the rivet (7) from the top of the head, the top of the head is flattened and at the same time the shaft (7b) of the rivet (7) is pressed. A buckling deformation stress in the diameter expansion direction acts. This deformation stress acts greatly as it reaches the upper end of the shaft portion (7b), and exerts a plastic deformation force in the direction of expanding the diameter of the shaft portion (7b). For this reason, as shown in FIG. 6, while the shaft portion (7b) is in close contact with the inner peripheral surface of the rivet hole (8), the shaft portion is located at the portion where the locking recess (14) in the upper end region exists. A part of the material is deformed outwardly to form a locking projection (17), and this is engaged in a state of biting into the locking recess (14). Moreover, the locking recess (14) has a deep bottom surface inclined substantially obliquely outward from the upper inner peripheral surface of the rivet hole (8) to the upper surface side hole peripheral portion, and the rivet hole (8 ), The locking projection (17) protruding from the material of the shaft portion (7b) is completely in the recess (14). Without any gaps, and a strong engagement state between the recessed portion (14) and the locking convex portion (17) is realized.

  Therefore, the tab (6) is reliably prevented from rotating around the rivet by the above-described engagement in the state after the tab (6) is mounted, so that a good anti-rotation action and consequently a tab rotation prevention function can be achieved. .

  Next, various specific design elements for preferable implementation of the present invention will be described.

  First, the number of the notches (12) of the punch (11) is not particularly limited in the present invention, but it is desirable that the number of notches (12) is in the range of 3 to 10 and arranged at equal intervals in the circumferential direction. If the number is less than three, the effect of preventing the rotation of the tab is likely to be insufficient. On the other hand, the upper limit of the number can be arbitrarily set in relation to the diameter of the punch (11) and consequently the diameter of the rivet hole (8). In the case of the tab attachment rivet (7) of the can lid (1) for beverage cans, the diameter is about 3.0 to 4.0 mm. In this case, setting it to 10 or less is necessary and sufficient. It is possible to obtain the effect of preventing the rotation of the tab. In the case of the rivet diameter, the particularly preferred number of notches (12) is about 4 to 8 on the basis of 6 shown in the illustrated embodiment. If the number is too large, the distance between adjacent notches (12) and (12) will be short, and the adjacent recesses for locking (14) and (14) will be too close. Obstructing the realization of a detent effect.

  The width (W) of the notch (12) of the punch (11), that is, the opening width of the notch (12) on the outer peripheral surface of the punch (11) shown in FIG. Although it is arbitrarily set in relation to the above, it is not particularly limited, but it is preferable to set in a range of approximately 0.5 to 1.5 mm. If this is too small or too large, it is difficult to ensure a good anti-tab rotation effect. That is, if it is less than 0.5 mm, the width of the locking recess (14) formed by the notch (12) is small, and as a result, the material of the shaft (7b) of the rivet (7) is difficult to enter. Thus, it becomes difficult to form a favorable locking projection (17). On the contrary, the upper limit of the width (W) is not particularly limited, but if it exceeds 1.5 mm, the upper limit of the width (W) is limited by the number of the locking recesses (14) in the circumferential direction, and the tab ( It becomes difficult to maintain the above-mentioned good engagement relationship for the detent of 6).

  The cross-sectional shape of the notch (12) of the punch (11) may be a notch (112) having a triangular cross section as shown in FIG. 7 in addition to the U shape as shown in FIG. It is good also as a thing by the notch part (212) of circular arc shape as shown in FIG. Other shapes are also acceptable.

  Moreover, although the back bottom surface (12a) of the notch (12) may be a horizontal one parallel to the lower surface (13) of the punch (11), it is inclined outward as shown in FIG. By tilting upward, it is advantageous in that it is possible to form a favorable recess for locking (14) that is stable in shape in the rivet hole (8). In this case, the inclination angle (θ) of the back bottom surface (12a) is preferably set in the range of 10 to 30 ° with respect to the plane on which the lower surface of the punch (11) exists, and in particular in the range of 15 to 25 °. It is preferable to set.

  In addition, the height (H) at the outer end of the notch (12), that is, the punch (11), no matter what angle the inclination angle (θ) of the back bottom surface (12a) is set. The distance from the peripheral edge of the lower end of the outer peripheral surface to the maximum height position is in the range of 0.3 to 1.0 times the thickness of the tab (6), and specifically, for example, 0.12 mm to 0.35 mm. Should be set in the range of.

  If the height (H) is less than 0.3 times the thickness of the tab, it is difficult to form a locking recess (14) having a sufficient depth on the rivet hole (8) side of the tab (6). It will be something. On the other hand, if it exceeds 1.0 and is too large, the stroke distance of the punch (11) required for drilling the rivet hole (8) becomes long, which is not preferable in terms of production efficiency. And we cannot expect the increase of the detent effect corresponding to this against such a disadvantage.

  Next, examples carried out to confirm the effect of the present invention will be shown.

  An aluminum sheet (A5182) having a thickness of 0.25 mm was used as the material sheet for the can lid body (2), and an aluminum sheet (A5182) having a thickness of 0.35 mm was used as the material sheet for the tab for opening the can (6). A can lid main body (2) and a tab (6) each having a shape as shown in FIG.

  The rivet (7) on the side of the can lid body (2) was formed to an outer diameter of 3.0 mm and a height of 1.5 mm at the time of stamping.

  On the other hand, the rivet hole (8) of the tab (6) was punched and formed using a punch (11) having a diameter of 3.20 mm and having a notch (12) having the following specifications at the peripheral edge of the lower surface.

[Notch specifications]
Number: 6 Back surface tilt angle (θ): 20 degrees Height on outer peripheral surface (H): 0.25 mm
Width on outer peripheral surface (W): 0.8 mm
Then, after inserting the rivet (7) into the rivet hole (8) and setting the tab (6) on the upper surface of the can lid body (2), the rivet (7) is crimped according to a conventional method, A can lid (1) with a tab was produced.

  The can lid (1) manufactured in this way has a good anti-rotation function that does not easily cause rotational displacement even when the operation end of the tab (6) is pushed considerably horizontally (horizontal direction) with a fingertip. I was able to confirm that.

  The present invention is applicable to all metal cans such as aluminum cans and steel cans used in beverage cans, canned cans and the like having an easy open function.

It is a top view of the can lid with a tab concerning this invention. It is an expanded sectional view of the AA line of FIG. The punch used for punching and forming a rivet hole in a tab is shown. FIG. (A) is a bottom view of the punch, (b) is a front view of the lower end portion, and (c) is a diagram (a). It is sectional drawing of a BB line. The formation process of rivet holes by punching is schematically shown. Fig. (A) is a cross-sectional view of the state before punching, Fig. (B) is a cross-sectional view of the initial state of punching, and Fig. (C) is the middle stage of punching. FIG. 4D is a cross-sectional view showing a state after punching is completed. The shape of the rivet hole formed in the tab is shown, in which FIG. (A) is a cross-sectional view, FIG. (B) is a plan view, and FIG. (C) is a bottom view. The structure of the attachment part which crimped the rivet and attached the tab is shown, and FIG. (A) is a sectional view taken along the line CC in FIG. 5 (b), and FIG. It is sectional drawing of a DD line. FIG. 9 shows a modification of the punch for forming rivet holes, in which FIG. (A) is a front view of the lower end portion of the punch shown with a part cut away, and (B) is a bottom view. FIG. 7 shows another modified example of the rivet forming punch, in which FIG. (A) is a front view of the lower end portion of the punch shown with a part cut away, and (b) is a bottom view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Can lid 2 ... Can lid main body 3 ... Top plate part 4 ... Cutting line 5 ... Lid piece 6 ... Open can Tab 7... Rivet 7 a... Ridge diameter expansion top 7 b... Rivet shaft 8. Rivet hole 11... Punch 11 a. Periphery 12... Notch 12 a .. back bottom surface of notch 13 .. bottom surface of punch 14... Recessed portion 14 a for locking 14 a .. bottom surface of recess 17. Stop projection

Claims (8)

On the top of the top surface of the can lid body, in the can lid where the tab for opening the can is attached by riveting corresponding to the lid piece defined by the cut line,
In the circular rivet hole of the tab, one or a plurality of locking recesses extending substantially obliquely outward from the upper part of the inner peripheral surface to the peripheral part of the upper surface side hole are formed.
A tab for opening a can characterized in that a locking convex portion protruding outward from an upper outer peripheral surface of a shaft portion of a rivet integrally formed with the can lid main body is engaged with the concave portion in a biting state. Can lid with.   2. The can lid with a tab for opening a can according to claim 1, wherein a bottom surface of the recess for locking is formed into a sag-like curved surface curved inward of the rivet hole.   3. The can lid with a tab for opening a can according to claim 1, wherein the recesses for locking are arranged at equal intervals in a range of 3 to 10 in the direction around the rivet hole. On the top surface of the can lid body, in the method of manufacturing the can lid, the tab for opening the can is attached by riveting corresponding to the lid piece defined by the cut line.
The rivet hole of the tab is formed by punching using a punch for punching having one or a plurality of cutouts on the peripheral edge of the lower surface. By this punching process, the circular rivet hole is formed from the upper part of the inner peripheral surface. Forming one or a plurality of locking recesses inclined substantially diagonally outwardly from the peripheral edge of the upper surface side hole;
By inserting a rivet protruding from the top plate surface of the can lid body into the rivet hole and caulking from above, the locking convex portion protruding from the outer peripheral surface of the rivet shaft bites into the locking concave portion. A method for producing a can lid with a tab for opening a can, wherein the can lid is engaged with a state.   The notch portion of the punch is a notch portion having a concave groove shape in which the bottom surface is inclined obliquely upward from the middle portion of the radial line on the lower surface of the punch to the outer peripheral surface of the lower end portion. Manufacturing method of can lid.   The method of manufacturing a can lid with a tab for opening a can according to claim 5, wherein an inclination angle of a back bottom surface of the notch is set in a range of 10 to 30 ° with respect to a plane on which a punch bottom surface exists.   The notch portion of the punch has a height on the outer peripheral surface of the punch set to 0.3 to 1.0 times the wall thickness of the tab material. Manufacturing method of can lid with tab. The method for manufacturing a can lid with a tab for opening a can according to any one of claims 4 to 7, wherein the notch portions of the punch are provided in a range of 3 to 10 at equal intervals in the circumferential direction.

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