Lid body and original plate thereof

Abstract

To provide a lid body allowed to realize both of keeping a strong fit state of the lid body with a top curled portion of a container body and easy opening of the lid body.SOLUTION: A lid body 1 is obtainable by drawing an outer peripheral edge of an original plate obtained by blanking a laminate sheet having a paper board laminated with synthetic resin to form a top face portion 2 and a peripheral wall 3 extending around the same, and folding back a lower part of the peripheral wall 3 inward to provide an inner face portion 4 extending around an inner surface of the peripheral wall 3. At least one recess 5 is provided in an upper end face 4a of the inner face portion 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lid body and an original plate for the lid, which are obtained by punching a laminated sheet made of paperboard laminated with synthetic resin, and narrowing the outer edge of the original plate to form a top surface and a peripheral wall surrounding it. [Background technology]

[0002] A known lid body having a top surface and a peripheral wall is constructed by forming a grooved area consisting of numerous linear grooves extending radially inward from the outer periphery in a laminated sheet made of paperboard laminated with synthetic resin, punching the laminated sheet along the outer periphery with a circular blade to form a disk-shaped original plate, squeezing this disk-shaped original plate along the grooved area to form the top surface and a peripheral wall that surrounds it, and folding a lower portion of the peripheral wall inward to provide an inner surface portion that surrounds the inner surface of the peripheral wall (for example, Patent Document 1).

[0003] An example of a conventional lid body (31) that serves as the base of the lid body of the present invention will be described with reference to Figs.

[0004] As shown in FIG. 14, the lid body (31) consists of a top surface portion (32) and a peripheral wall (33) that runs around the top surface portion (32). The peripheral wall (33) has an inner surface portion (34) that runs around the inner surface of the peripheral wall (33) by folding its lower portion inward.

[0005] Such a lid body (31) is attached to a cup-shaped container body (41) as shown in Fig. 15. The container body (41) is provided with a top curl portion (42) formed by outwardly curling the upper end portion of the container body (41) as shown in Fig. 16. When the lid body (31) and the container body (41) are fitted together, as shown in Fig. 16, the upper end surface (34a) of the inner side surface portion (34) of the lid body (31) is positioned below the top surface portion (32) by the vertical height of the top curl portion (42), and the upper end surface (34a) of the inner side surface portion (34) of the lid body (31) faces the outer end portion of the top curl portion (42) from below, thereby ensuring a proper fitting state.

[0006] The container body (41) and the lid (31) are rotationally symmetrical, and the cross-sectional view shown in FIG. 16 has the same shape on any cross-sectional line passing through the center of the lid (31).

[0007] The cover body (31) is obtained by forming a circular original plate (51) as shown in Fig. 17. As shown in the figure, the outer peripheral edge of the original plate (51) is provided with a groove-like region (52) in which a large number of longitudinal grooves (52a) and transverse grooves (52b) extending from the outer periphery toward the radially inward direction are alternately arranged. The peripheral wall (33) of the cover body (31) is formed by narrowing the outer peripheral edge of the original plate (51) along a circular inner peripheral line (53) located slightly radially inward from the end of the longitudinal groove (52a), and further, the inner surface portion (34) of the peripheral wall (33) is formed by folding back a portion radially outward from the intermediate line (54) along a circular intermediate line (54) located slightly radially outward from the end of the transverse groove (52b). The inner side portion (34) is bonded to the inner surface of the peripheral wall (33) at a relatively low temperature and a medium to low polymerization pressure, and the upper end surface (34a) of the inner side portion (34) is formed by the outer peripheral surface (55) of the original plate (51).

[0008] The diameter of the top surface (32) of the lid body (31) is 93.15 mm, the height of the peripheral wall (33) is 12.5 mm, the outer diameter D1 of the original plate (51) is 134.84 mm, the outer diameter D2 of the inner circumference line (53) is 93.15 mm, and the outer diameter D3 of the middle line (54) is 118.15 mm.

[0009] The original plate (51), as shown in Fig. 18, is obtained by punching a laminated sheet (56) made of paperboard laminated with synthetic resin with a circular blade (57). The laminated sheet (56) is long, and its width is larger than the diameter of the blade (57). In other words, the width of the laminated sheet (56) = the diameter of the blade (57) + a margin of a required size.

[0010] The diameter C of the blade (57) is 134.84 mm, which is equal to the outer diameter D1 of the original plate (51), and the width W2 of the laminated sheet (56) is 144 mm. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2007-99394 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0012] As shown in Fig. 16, this type of lid (31) is attached to a container body (41) having a top curl portion (42), and in this application, a strong fit between the lid (31) and the top curl portion (42) of the container body (41) is required. However, if the fit between the lid (31) and the top curl portion (42) is too strong, the inner side surface portion (34) of the lid (31) rubs strongly against the top curl portion (42) when the lid (31) is opened, generating resistance, which results in the problem that the lid (31) is difficult to open. It has been difficult to maintain a strong fit between the lid (31) and the top curl portion (42) of the container body (41) and to make the lid (31) easy to open at the same time.

[0013] In addition, in this type of lid body (31), as shown in FIG. 18, the original plate (51) is obtained by punching out a long laminated sheet (56) with a circular blade (57). Therefore, the portion of the laminated sheet (56) that is not used as the original plate (51) is discarded. Therefore, from the standpoint of resource conservation and cost reduction, it is an issue to reduce the amount of laminated sheet used and discarded.

[0014] In view of the above problems, the object of the present invention is to provide a lid body and an original plate therefor that can maintain a strong fit between the lid body and the top curl portion of the container body while also making it easy to open the lid body.

[0015] In view of the above problems, another object of the present invention is to provide a lid and an original plate therefor that enable a reduction in the amount of laminated sheet used and the amount of waste. [Means for solving the problem]

[0016] In order to achieve the above object, the present invention comprises the following aspects.

[0017] 1) A lid body obtained by punching a laminated sheet of paperboard laminated with synthetic resin, narrowing the outer edge of the original plate to form a top surface and a peripheral wall surrounding the top surface, and folding back a lower portion of the peripheral wall to provide an inner surface portion that surrounds the inner surface of the peripheral wall, A lid body characterized in that at least one recess is provided on an upper end surface of the inner side surface portion.

[0018] That is, while the conventional lid has a rotational symmetry shape and the upper end surface of the inner side surface has the same height all around based on the lower end of the peripheral wall, in this invention, at least one (preferably one to four) part with a lower height, i.e., a recess, is formed on the upper end surface of the inner side surface. The recess can be obtained, for example, by providing a cut portion in the original plate that is removed from the circular portion, and in this case, the cut portion of the original plate becomes the recess when molded into the lid. The method of obtaining the recess is not limited to providing a cut portion in the original plate that is removed from the circular portion. The shape of the recess is, for example, an arc shape, but is not particularly limited, and the number and depth of the recess are set in consideration of molding defects in the manufacturing process.

[0019] 2) The lid body according to 1) above, characterized in that the at least one recess is used as an opening start position when opening the lid body from the container body.

[0020] 3) The lid according to 1) or 2), wherein the at least one recess is obtained by molding an original plate having a cut portion obtained by cutting a part on its circumference into the lid.

[0021] The depth of the cut portion (the maximum distance from the cut line to the corresponding circumference) is the depth of the deepest part of the recess of the lid. Here, the cut line cutting a part of the circumference is, for example, linear, and in this case, the shape of the recess is an arc. The depth of the cut portion of the original plate = the dimension of the deepest part of the recess of the lid is preferably 0.5 mm to 2 mm.

[0022] 4) The lid according to claim 3), wherein the cut portion has a shape obtained by cutting in a straight line between two points on the circumference.

[0023] 5) The lid according to 4) above, wherein the at least one recess is provided at two opposing positions on the circumference.

[0024] 6) The cover according to 5) above, characterized in that at least one of the at least one recesses is provided in a middle portion between two recesses facing each other on the circumference.

[0025] 7) In a blank for forming a lid, the blank is obtained by punching a laminated sheet obtained by laminating a synthetic resin onto a paperboard, narrowing the outer edge of the blank to form a top surface portion and a peripheral wall surrounding the top surface portion, and folding back a lower portion of the peripheral wall to form an inner surface portion that surrounds the inner surface of the peripheral wall. A master plate characterized in that a cut portion is provided by cutting a portion of the circumference. Effect of the Invention

[0026] In the lid of 1) above, the recess can be used as the starting position when opening the lid from the container body, which makes it possible to maintain a tight fit between the lid and the top curl part of the container body while also making it easy to open the lid. The recess can be obtained by providing a cut part in the original plate that is removed from the circular part, which makes it possible to narrow the width of the laminated sheet when the margin for punching with a blade is the same as in the conventional method, thereby making it possible to reduce the amount of laminated sheet used and wasted.

[0027] According to the lid body of 2) above, when this lid body is attached to a container body having a top curl portion and used, the recessed portion of the lid body does not come into contact with the top curl portion of the container body when the lid body is opened. Therefore, by opening the lid body from the direction of the recessed portion, the area where the inner surface of the lid body rubs strongly against the top curl portion of the container body is reduced, and the resistance generated when opening the lid body is reduced.

[0028] According to the lid 3) described above, by providing a cut portion on a portion of the circumference of the original plate, a laminated sheet having a narrower width than before can be used, which reduces the amount of laminated sheet used and disposed of, thereby reducing costs.

[0029] According to the lid body of 4) above, since the cut portion is in a straight line, by using a laminated sheet narrower than the width of a conventional sheet and punching it by protruding a blade from the laminated sheet, the margin required for punching with the blade is eliminated and an original plate with a cut portion on part of the circumference can be obtained. This further reduces the amount of laminated sheet used and wasted, thereby reducing costs.

[0030] According to the lid of 5) above, by using a narrow laminated sheet, it is not necessary to process a circular blade to form a cutting portion, so that the versatility of the blade is increased and costs can be reduced.

[0031] According to the lid body of 6) above, when the laminated sheet is punched with a blade having a cutting portion for forming a recess in the middle to obtain the original plate, it is possible to reduce the punching interval by at least the depth of the cutting portion for forming the recess in the middle, thereby reducing the amount of laminated sheet used and disposed of, and reducing costs.

[0032] According to the above-mentioned 7) original plate, the amount of laminated sheet used to obtain the original plate and the amount of waste are reduced, which enables the cost of the original plate to be reduced, and also the cost of the lid body obtained by molding this original plate to be reduced. [Brief description of the drawings]

[0033] [Figure 1] FIG. 2 is a perspective view showing a cover according to the embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing a state in which a lid body according to an embodiment of the present invention is attached to a container body. [Diagram 3] 3 is a vertical cross-sectional view taken along a center line passing through the center of a recess in the lid body of FIG. 2. [Figure 4] 4 is a vertical cross-sectional view showing a state in the middle of opening the lid from the state shown in FIG. 3. FIG. [Diagram 5] FIG. 5 is a plan view showing an original plate for obtaining the lid body shown in FIGS. 1 to 4. [Figure 6] FIG. 2 is a plan view showing an original plate for obtaining a lid body having two recesses. [Figure 7] FIG. 13 is a plan view showing an original plate for obtaining a lid body having three recesses. [Figure 8] FIG. 13 is a plan view showing an original plate for obtaining a lid body having four recesses. [Figure 9] 6 is a plan view showing a schematic diagram of a part of the manufacturing process for obtaining the master plate shown in FIG. 5. [Figure 10] 7 is a plan view that illustrates a schematic diagram of a part of the manufacturing process for obtaining the master plate illustrated in FIG. 6. [Figure 11] 8 is a plan view that illustrates a schematic diagram of a part of the manufacturing process for obtaining the master plate illustrated in FIG. 7. [Figure 12] 9 is a plan view showing a schematic diagram of a part of the manufacturing process for obtaining the master plate shown in FIG. 8. [Figure 13] 9 is a plan view showing a schematic diagram of another example of a part of the manufacturing process for obtaining the master plate shown in FIG. 5 to FIG. 8. [Figure 14] FIG. 11 is a perspective view showing a conventional lid. [Figure 15] FIG. 11 is a perspective view showing a state in which a conventional lid is attached to a container body. [Figure 16] 16 is a vertical cross-sectional view taken along the center line of the lid of FIG. 15. [Figure 17] FIG. 1 is a plan view showing an original plate for obtaining a conventional lid body. [Figure 18] 18 is a plan view showing a schematic diagram of a part of the manufacturing process for obtaining the master plate of FIG. 17. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings.

[0035] Figures 1 to 5 and 9 show a cover (1) according to a first embodiment of the present invention. Figure 1 corresponds to Figure 14, Figure 2 corresponds to Figure 15, Figure 3 corresponds to Figure 16, Figure 5 corresponds to Figure 17, and Figure 9 corresponds to Figure 18, respectively.

[0036] The lid body (1), like the conventional one, consists of a top surface portion (2) and a peripheral wall (3) that runs around the top surface portion (2), and the peripheral wall (3) has an inner surface portion (4) that runs around the inner surface of the peripheral wall (3) by folding its lower portion inward.

[0037] The cover (1) of this embodiment differs from conventional ones in that one arc-shaped recess (5) is provided on the upper end surface (4a) of the inner side surface portion (4).

[0038] In FIG. 2, the recess (5) indicated by the dashed line cannot be seen from the outside, but when the lid (1) is removed, it can be seen from the back side of the top surface (2), as shown in FIG.

[0039] The lid body (1) has a recess (5) formed on the inner side surface portion (4), and in Figure 3, which is a cross-sectional view passing through the center of the arc-shaped recess (5) when the lid body (1) is attached to a container body (41) having a top curl portion (42), the right side is the same as the conventional one, while the left side is different from the conventional one in that the upper end surface (4a) of the inner side surface portion (4) is recessed.

[0040] Therefore, with this lid body (1), when the lid body (1) and the container body (41) are fitted together, as shown on the right side of Figure 3, the upper end surface (4a) of the inner side surface portion (4) of the lid body (1) is positioned below the top surface portion (2) by the vertical height of the top curl portion (42), and the upper end surface (4a) of the inner side surface portion (4) of the lid body (1) faces the outer end portion of the top curl portion (42) from below, thereby ensuring a proper fitting state, and at one point on the circumference, a recess (5) formed by recessing the upper end surface (4a) of the inner side surface portion (4) of the lid body (1) faces the outer end portion of the top curl portion (42) from below. The reference symbol (5a) indicates the deepest position of the recess (5), and the reference symbol (5b) indicates the edge of the recess (5).

[0041] The recess (5) is suitable as a starting position for opening the lid (1), and the lid (1) provided with this recess (5) is opened from the portion where the recess (5) is provided, as shown in FIG. 4. In this way, at the starting position for opening, the recess (5) (the portion without the inner side surface portion (4)) and the top curl portion (42) rub against each other, so that the resistance generated when opening the lid (1) is reduced. Therefore, the lid (1) can be easily opened. Since the recess (5) is provided at only one place on the circumference, the tight fitting state between the lid (1) and the top curl portion (42) is maintained, and thus it is possible to maintain the tight fitting state between the lid (1) and the container body (41) and to easily open the lid (1), which was difficult to achieve in the past.

[0042] In addition, in order to enable consumers to open the lid body (1) from the direction in which the recess (5) is molded, printing indicating the start position for opening may be applied to the outer surface of the top surface (2) or the peripheral wall (3) at a position corresponding to the recess (5) shown by the dashed line in Figure 2.

[0043] The cover body (1) is obtained by forming the original plate (11) shown in FIG. 5. As in the conventional method, the outer peripheral edge of the original plate (11) is provided with a groove-like region (52) in which a large number of long grooves (52a) and short grooves (52b) extending from the outer periphery toward the inside in the radial direction are alternately arranged. The peripheral wall (3) of the cover body (1) is formed by narrowing the outer peripheral edge of the original plate (11) along a circular inner peripheral line (53) located slightly radially inside the end of the long groove (52a), and further, the inner side surface portion (4) of the peripheral wall (3) is formed by folding back the part radially outside the middle line (54) along a circular middle line (54) located slightly radially outside the end of the short groove (52b). As a result, the upper end surface (4a) of the inner side surface portion (4) is formed by the outer peripheral surface (55) of the original plate (51).

[0044] The dimensions are the same as before, with the diameter of the top surface (2) of the lid body (1) being 93.15 mm, the height of the peripheral wall (3) being 12.5 mm, the outer diameter D1 of the original plate (11) being 134.84 mm, the outer diameter D2 of the inner circumference line (53) being 93.15 mm, and the outer diameter D3 of the middle line (54) being 118.15 mm.

[0045] As a difference from the conventional method, the original plate (11) for obtaining the lid body (1) has a cutting line (11a) for cutting in a straight line between two points on the circumference. By forming this original plate (11), a cut portion (12) surrounded by the cutting line (11a) and an imaginary outer peripheral line (55a) shown by a two-dot chain line becomes the recess (5) in the lid body (1).

[0046] Although an example in which the number of recesses (5) provided in the cover body (1) is one is shown in Figures 1 to 4, the number of recesses (5) may be two or more, for example, two (one additional recess facing the recess (5) shown in the figure), three (two opposing recesses and one additional recess between them), or four (two opposing recesses and two additional recesses between them).

[0047] In the following, the illustration of the lid body (1) will be omitted and the shapes of the original plates (13), (15), and (17) for forming the lid body (1) having two, three, or four recesses (5) will be described. In the following explanation, the same reference numerals will be used to designate parts having the same shape as the original plate (11) for forming the lid body (1) having one recess (5), and the explanation thereof will be omitted, and only the differences will be described.

[0048] As shown in Fig. 6, the original plate (13) for forming the lid body (1) having the two recesses (5) has a shape in which a cutting line (13b) that connects two points on the circumference in a straight line is added to the position opposite the cutting line (13a) corresponding to Fig. 5, as shown in Fig. 5. By forming this original plate (13), the cut portions (14) surrounded by the cutting lines (13a) and (13b) and the imaginary outer peripheral line (55a) shown by the two-dot chain line become the two recesses (5) in the lid body (1).

[0049] As shown in Fig. 7, the original plate (15) for forming the lid body (1) having the three recesses (5) has a shape in which a cutting line (15c) that connects two points on the circumference in a straight line is added between (one of two) the cutting lines (15a) and (15b) corresponding to Fig. 6, as an addition to Fig. 6. By forming this original plate (15), the cut portions (16) surrounded by the cutting lines (15a), (15b), and (15c) and the imaginary outer peripheral line (55a) shown by a two-dot chain line become the three recesses (5) in the lid body (1).

[0050] As shown in Fig. 8, the original plate (17) for forming the lid body (1) having the four recesses (5) has a shape added to Fig. 7 by adding a cutting line (17d) that connects two points on the circumference in a straight line between the cutting lines (17a) and (17b) (the other of the two) to the cutting lines (17a), (17b), and (17c) corresponding to Fig. 7. By forming this original plate (17), the cut portions (18) surrounded by the cutting lines (17a), (17b), (17c), and (17d) and the imaginary outer peripheral line (55a) shown by the two-dot chain line become the four recesses (5) in the lid body (1).

[0051] The above-mentioned original plates (11), (13), (15), and (17) are obtained by punching out long laminated sheets (21), (22), and (23) made of paperboard laminated with synthetic resin, using blades (24), (25), (26), (27), (28), (29), and (30), in the same manner as in the past. More specifically, the laminated sheets (21), (22), and (23) are made by laminating a 20 μm-thick polypropylene resin or high-density polyethylene resin on the front side of a 320 g per square meter paperboard, and laminating a 20 μm-thick low-density polyethylene resin or linear low-density polyethylene resin on the back side. Here, the width of the laminated sheets (21), (22), and (23) used is narrower than in the past, and the shape of the blades (24), (25), (26), (27), (28), (29), and (30) may be the same as in the past or may be modified from the conventional shape.

[0052] The original plate (11) for forming the cover body (1) having one recess (5) shown in FIG. 5 is obtained by punching the laminated sheet (21) with a circular blade (24) as shown in FIG. 9. The circular blade (24) is the same as that shown in FIG. 18 (57), and its diameter C is 134.84 mm, which is equal to the outer diameter D1 of the original plate (11). In contrast, the width W1 of the laminated sheet (21) is 133 mm, which is narrower than the width W2 of that shown in FIG. 18 (56) and narrower than the diameter C of the blade (24). In this dimensional relationship, one point on the outer periphery of the blade (24) is in contact with one edge (21b) of the laminated sheet (21), and the laminated sheet (21) is punched out in a state in which a part of the outer periphery of the blade (24) protrudes by P1=C-W1 from the other edge (21a) of the laminated sheet (21). Therefore, the obtained original plate (11) is manufactured so that a part of the other edge (21a) of the laminated sheet (21) is used as the cutting line (11a) and the cut portion (12) (the depth of which is P1 = 1.84 mm) is provided outside the cutting line (11a). In other words, the cutting line (11a) is not provided on the blade (24) but is formed by a part of the other edge (21a) of the laminated sheet (21). In this way, the original plate (11) having the cut portion (12) at one place on the circle is obtained by using the circular blade (24) and without a process of adding the cutting line (11a). In addition, the original plate (11) having one cut portion (12) (depth of 1.84 mm) shown in Figure 5 can also be obtained by using the same laminate sheet (21) and blade (24) and aligning one point on the outer periphery of the blade (24) with the other edge (21a) of the laminate sheet (21) and hammering the blade (24) into the laminate sheet (21).

[0053] The original plate (13) for forming the cover body (1) having the two recesses (5) shown in Fig. 6 is obtained by punching a laminated sheet (21) with a circular blade (24) as shown in Fig. 10. Both the laminated sheet (21) and the circular blade (24) are the same as those shown in Fig. 9. The difference is that the center of the blade (24) coincides with the center of the width of the laminated sheet (21) (the center of both edges (21a) and (21b)), so that the laminated sheet (21) is punched out with parts of the outer periphery of the blade (24) protruding by P2=(C-W1) / 2 from both edges (21a) and (21b) of the laminated sheet (21) at positions facing each other. Therefore, the obtained original plate (13) is manufactured so that parts of both edges (21a) and (21b) of the laminated sheet (21) are used as cutting lines (13a) and (13b) and cut portions (14) (with a depth of 0.92 mm) outside of these. In other words, neither of the two cutting lines (13a) and (13b) are provided on the blade (24), but are formed by parts of both edges (21a) and (21b) of the laminated sheet (21). In this way, an original plate (13) having cut portions (14) in two places on a circle is obtained using a circular blade (24) and without a process of adding cutting lines (13a) and (13b).

[0054] The original plate (15) for forming the cover body (1) having the three recesses (5) shown in Fig. 7 is obtained by punching a laminated sheet (21) with a substantially circular (not completely circular) blade (25) as shown in Fig. 11. The laminated sheet (21) is the same as that shown in Fig. 10. The difference from Fig. 10 is that the blade (25) has a straight line portion (25a) for forming a cutting line formed at one location on its periphery, and this straight line portion (25a) of the blade (25) is aligned with the center of the width of the laminated sheet (21) (the center of both edges (21a) and (21b)). Accordingly, the center of the blade (25) is also made to coincide with the center of the width of the laminated sheet (21), so that the laminated sheet (21) is punched out in a state where parts of the outer peripheral edge of the blade (25) protrude from both edges (21a) and (21b) of the laminated sheet (21) by P2=(C-W1) / 2 at positions facing each other. Therefore, the obtained original plate (15) is manufactured to have two cut portions (16) (depth of 0.92 mm) on the outside of the cut lines (15a) and (15b) on parts of both edges (21a) and (21b) of the laminated sheet (21) as in FIG. 10, and in addition, a third cut portion (16) is produced by the straight portion (25a) of the blade (25). The straight portion (25a) of the blade (25) is formed so that the depth of the third cut portion (16) is the same depth (0.92 mm) as the other two cut portions (16). In this way, a blank (15) having cut portions (16) at three circular locations is obtained using a blade (25) having a straight portion (25a) at one circular location.

[0055] The original plate (17) for forming the cover body (1) having the four recesses (5) shown in Fig. 8 is obtained by punching a laminated sheet (21) with a substantially circular (not completely circular) blade (26) as shown in Fig. 12. The laminated sheet (21) is the same as that shown in Fig. 10. The difference from Fig. 10 is that the blade (26) has straight portions (26a) and (26b) for forming cutting lines formed at two opposing places on the outer periphery, and the two straight portions (26a) and (26b) of the blade (26) are aligned with the center of the width of the laminated sheet (21) (the center of both edges (21a) and (21b)). Accordingly, the center of the blade (26) is also made to coincide with the center of the width of the laminate sheet (21), so that the laminate sheet (21) is punched out in a state in which parts of the outer peripheral edge of the blade (26) protrude from both edges (21a) and (21b) of the laminate sheet (21) by P2=(C-W1) / 2 at positions facing each other. Therefore, the obtained original plate (17) is produced as shown in Fig. 10, with parts of both edges (21a) and (21b) of the laminate sheet (21) as cutting lines (17a) and (17b) on the outside of these, and with two further cut portions (18) (0.92 mm deep), in addition, by the straight portions (26a) and (26b) of the blade (26). The straight portions 26a, 26b of the blade 26 are formed so that the depth of the third and fourth cut portions 18 is the same depth (0.92 mm) as the other two cut portions 18. In this way, a blank 17 having cut portions 18 at four circular locations is obtained by using a blade 26 having straight portions 26a, 26b at two circular locations.

[0056] In the embodiment shown in Figs. 9 to 12, the distance by which the blades 24, 25, and 26 protrude from the laminated sheet 21 is 1.84 mm or 0.92 mm, but is not limited thereto and may be between 0.5 mm and 2 mm. The depth of the straight line portions 25a, 26a, and 26b provided on the circumference of the blades 25 and 26 is 0.92 mm, but is not limited thereto and may be between 0.5 mm and 2 mm. The width W1 of the laminated sheet 21 is 133 mm, but is not limited thereto.

[0057] The original plates (11), (13), (15), and (17) shown in Figures 5 to 8 can also be produced as shown in Figures 13(a), (b), (c), and (d) instead of those shown in Figures 9 to 12.

[0058] In FIG. 13(a), the blade (27) is circular (specifically, its diameter is 134.8 mm) and has a straight line portion (27a) (depth of 1.84 mm) that connects two points on the circumference in a straight line at one point on the circumference, and the shape of the blade (27) is formed to match the shape of the original sheet (11). The width of the laminated sheet (22) is narrower than the conventional width W2 (144 mm) by about 1.84 mm, which corresponds to the depth of the straight line portion (27a) of the blade (27). The straight line portion (27a) of the blade (27) faces one edge (22a) of the laminated sheet (22) with a small gap therebetween, and the outer periphery of the blade (27) facing the straight line portion (27a) faces the other edge (22b) of the laminated sheet (22) with a small gap therebetween, so that the laminated sheet (22) is punched out. Therefore, the obtained original plate (11) is manufactured so as to have a cut portion (12) (having a depth of 1.84 mm) outside the straight portion (27a) of the blade (27) as the cutting line (11a).

[0059] 13(b), the blade (28) is circular (specifically, its diameter is 134.8 mm) with two opposing linear sections (28a) and (28b) (both with a depth of 0.92 mm) that connect two points on the circumference in a straight line added to the outer periphery, and the shape of the blade (28) is formed to match the shape of the original sheet (13). The width of the laminated sheet (23) is narrower than the conventional width W2 (144 mm) by about 1.84 mm, which corresponds to the combined depth of the two linear sections (28a) and (28b) of the blade (28). The laminated sheet (23) is punched out by arranging one straight portion (28a) of the blade (28) opposite one edge (23a) of the laminated sheet (23) with a small gap therebetween and the other straight portion (28a) of the blade (28) opposite the other edge (23b) of the laminated sheet (23) with a small gap therebetween. Thus, the obtained blank (13) is produced so as to have two cut portions (14) (each having a depth of 0.92 mm) on the outside of the straight portions (28a) and (28b) of the blade (28) as the cutting lines (13a) and (13b).

[0060] In Fig. 13(c), the blade (29) is circular (specifically, its diameter is 134.8 mm) and has two opposing points on the circumference and one point between them, with straight lines (29a), (29b), and (29c) (each of which has a depth of 0.92 mm) added to connect two points on the circumference in a straight line, so that the shape of the blade (29) is formed to match the shape of the original sheet (15). The width of the laminated sheet (23) is the same as that of Fig. 13(b). The laminated sheet (23) is punched out with one straight line (29a) of the blade (29) facing one edge (23a) of the laminated sheet (23) with a small gap therebetween, and the other straight line (29b) of the blade (29) facing the other edge (23b) of the laminated sheet (23) with a small gap therebetween. Therefore, the obtained original plate (15) is produced so that the straight portions (29a), (29b), and (29c) of the blade (29) serve as cutting lines (15a), (15b), and (15c) and have three cut portions (16) (each having a depth of 0.92 mm) outside thereof.

[0061] In Fig. 13(d), the blade (30) is circular (specifically, the diameter is 134.8 mm) and has two opposing points on the circumference and two points between them, with straight lines (30a), (30b), (30c), and (30d) (each of which has a depth of 0.92 mm) added to connect two points on the circumference in a straight line, so that the shape of the blade (30) is formed to match the shape of the original sheet (17). The width of the laminated sheet (23) is the same as that of Fig. 13(c). Then, one straight line part (30a) of the blade (30) faces one edge (23a) of the laminated sheet (23) with a small gap therebetween, and the other straight line part (30b) of the blade (30) faces the other edge (23b) of the laminated sheet (23) with a small gap therebetween, so that the laminated sheet (23) is punched out. Therefore, the resulting original plate (17) is produced to have four cuts (18) (each having a depth of 0.92 mm).

[0062] In addition, when comparing the embodiments shown in FIG. 13 with the embodiments shown in FIGS. 9 to 12, firstly, with regard to the width of the laminate sheets (21), (22), and (23), all the embodiments have the effect of being able to make the width of the laminate sheets (21), (22), and (23) narrower than conventional ones, but the embodiments shown in FIGS. 9 to 12 are superior to the one shown in FIG. 13 in that they have a greater effect of narrowing the width of the laminate sheet (21).

[0063] Secondly, in terms of the shapes of the blades (24), (25), (26), (27), (28), (29), (30), when the number of cutting portions (12), (14) of the original plates (11), (13) is two or less, the blades (24) can be punched out by protruding them outward from the laminated sheet (21), and thus the same circular blades (24) as before can be used without processing to provide straight portions on the circumference of the blades (24), thereby reducing costs, so that the shapes shown in Figs. 9 and 10 are superior to those shown in Figs. 13(a) and (b). Also, when the number of cutting portions (16), (18) of the original plates (15), (17) is three or more, the shapes shown in Figs. 11 and 12 are superior to those shown in Figs. 13(c) and (d) in that the number of cutting portions (16), (18) of the original plates (15), (17) is three or more, the blades (24) can be punched out by protruding them outward from the laminated sheet (21), and thus the number of processing steps to provide straight portions on the circumference of the blades (24) can be reduced by two, thereby reducing costs.

[0064] According to the manufacturing process shown in Figures 9 to 12, a circular blade (24) is used to punch out the laminated sheet (21) having a width smaller than the diameter of the blade (24), so that pieces of the laminated sheet (21) after punching fall into a collection section provided below the punching position. In the case where it is desired to wind up and collect the laminated sheet after punching, as shown in Figures 13(a) to (d), at least one straight portion (27a) (28a) (28b) (29a) (29b) (30a) (30b) may be provided on a portion of the circumference of the blades (27) (28) (29) (30), and this blade (27) (28) (29) (30) may be used to punch out the laminated sheet (22) (23) to a width greater than the minimum dimension of the blades (27) (28) (29) (30). Even in this case, since at least one straight portion (27a), (28a), (28b), (29a), (29b), (30a), (30b) is provided on the blade, the width of the laminated sheets (22), (23) can be reduced by the depth of the straight portion (27a), (28a), (28b), (29a), (29b), (30a), (30b) compared to conventional ones, i.e., the amount of laminated sheet used and the amount of waste can be reduced, resulting in a cost reduction.

[0065] A comparative experiment was conducted on the opening strength of the lid body (1) having one recess (5) of the above embodiment with a conventional lid body (31). In this experiment, a tensile tester was used, and the specific measurement procedure was to hold the lid body (1) (31) and pull vertically on the bottom of the container body (41) to which the lid body (1) (31) was attached, and record the value when the lid body (1) (31) came off the container body (41). The measurement results are shown in Table 1.

[0066] [Table 1]

[0067] From the results of the opening strength measurements shown in Table 1 above, the average value of the lid body (1) of the present invention is greater than the minimum value of the conventional product (a value at which it is possible to assume that a strong fitting state is maintained even at this value), and is several tens of percent smaller than the average value of the conventional product (a value at which the lid body (1) can be easily opened). This shows that it is possible to achieve both a strong fitting state between the lid body (1) and the top curl portion (42) of the container body (41) and the ease of opening the lid body (1).

[0068] In the above, the depth of the cut portions (12), (14), (16), and (18) of the original plates (11), (13), (15), and (17) (= the dimension of the deepest portion of the recess (5) of the lid body (1)) is preferably in the range of 0.5 mm to 2 mm. If it is less than 0.5 mm, the portion where the inner side surface portion (4) of the lid body (1) and the top curl portion (42) of the container body (41) rub against each other becomes large when the lid body (1) is opened, causing resistance, and the effect of easy opening cannot be obtained. If it is more than 2 mm, buckling occurs near the ends of the cut portions (12), (14), (16), and (18) in the process of folding back the lower portion of the peripheral wall (3) inward when forming the original plates (11), (13), (15), and (17) into the lid body (1), causing molding defects.

[0069] As described in the above embodiment, the number of cut portions 12, 14, 16, 18 of the original plates 11, 13, 15, 17 (= the number of recesses 5 of the cover 1) is preferably a maximum of 4. If the number is more than 4, buckling will occur near the ends of the cut portions 12, 14, 16, 18 in the process of folding back the lower portion of the peripheral wall 3 inward, resulting in molding defects.

[0070] In the above embodiment, the original plate (11), (13), (15), and (17) having the cut portions (12), (14), (16), and (18) obtained by cutting in a straight line between two points on the circumference is molded into the lid body (1), thereby obtaining the lid body (1) having the arc-shaped recess (5). However, the shapes of the cut portions (12), (14), (16), and (18) and the shape of the recess (5) are not limited to this and may be any shape. Similarly, the shapes of the straight portions 25a, 26a, 26b, 27a, 28a, 28b, 29a, 29b, 29c, 30a, 30b, 30c, 30d of the blades 25, 26, 27, 28, 29, 30 for cutting the original plates 11, 13, 15, 17 are not limited to those in the above embodiment. For example, although not shown, a triangular recess may be obtained by forming an original plate having a cutting portion in which a part of the circumference is cut into a triangular shape into a cover, or a rectangular recess may be obtained by forming an original plate having a cutting portion in which a part of the circumference is cut into a square shape into a cover, and for this purpose, the straight portions (cutting portions) of the blades may be changed to a triangular or square shape. [Explanation of symbols]

[0071] (1): Lid (2):Top section (3): Peripheral wall (4):Inner side part (4a):Top end surface (5): Recess (11): Original plate (11a): Cutting line (12): Cutting section (13): Original plate (13a)(13b): Cutting line (14): Cutting section (15): Original plate (15a)(15b)(15c): Cutting line (16): Cutting section (17): Original plate (17a)(17b)(17c)(17d): Cutting line (18): Cutting section (21)(22)(23): Laminated sheet (24)(25)(26)(27)(28)(29)(30):Blade

Claims

1. A lid is obtained by punching a laminated sheet of paperboard laminated with synthetic resin, narrowing the outer edge of the original plate to form a top surface and a peripheral wall surrounding the top surface, and folding back a lower portion of the peripheral wall to provide an inner surface portion that surrounds the inner surface of the peripheral wall, A lid body characterized in that at least one recess is provided on an upper end surface of the inner side surface portion.

2. The lid according to claim 1 , wherein the at least one recess is used as an opening start position when opening the lid from the container body.

3. 3. The lid according to claim 1, wherein the at least one recess is obtained by forming an original plate having a cut portion obtained by cutting a part of its circumference into the lid.

4. 4. The lid according to claim 3, wherein the cut portion is formed by cutting in a straight line between two points on a circumference.

5. 5. The cover according to claim 4, wherein said at least one recess is provided at two opposing positions on a circumference.

6. 6. The cover according to claim 5, wherein said at least one recess is provided in a middle portion between two recesses facing each other on the circumference.

7. A laminated sheet obtained by punching a paperboard sheet laminated with a synthetic resin is punched out from an original plate, and an outer peripheral edge of the original plate is narrowed to form a top surface portion and a peripheral wall surrounding the top surface portion, and a lower portion of the peripheral wall is folded inward to provide an inner surface portion that surrounds the inner surface of the peripheral wall. A master plate characterized in that a cut portion is provided by cutting a portion of the circumference.

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