JP2007091330A - Bottle can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a shape of a skirt part located in an area from flagging by forming a recess part in a portion of a first circumferential wall part, the portion being located in the area. <P>SOLUTION: A cap 22 of a bottle can has a male screw part 6 and a skirt part 7, the skirt part 7 having the first circumferential wall part connected to the lower end of the male part 6 in an axial direction of the can and having a diameter becoming gradually larger to the downward side and a second circumferential wall part connected to the lower end of the first circumferential wall part via a projection curved surface becoming projection to a radially outward side and having a diameter becoming gradually smaller downward. A recess part 7d extending circumferentially or intermittently existing circumferentially is formed in the portion of the first circumferential wall part, the portion being located in the area extending from the end 6a of the axial lower end of the male screw part 6 of the can to the direction by approximately 180 degrees opposite to the circumferential direction X in which the male part 6 extends. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bottle can in which a male screw part and a skirt part are formed in a base part.

In general, a bottle can filled with a beverage or the like is formed as follows.
First, as shown in FIG. 7A, a bottomed cylindrical body 1 is formed by drawing and ironing a metal plate made of an aluminum alloy or the like, and then a neck is formed at the opening of the cylindrical body 1. As shown in FIG. 7B, a large-diameter body 2 and a shoulder that is continuously connected to the upper end of the body 2 in the can axis direction and gradually reduced in diameter as it goes upward. 3 and a bottle can body 5 having a base portion 4 that extends upward and is connected to the upper end of the shoulder portion 3. And as shown in FIG.7 (c), after diameter-expanding once the part except this lower part 4a among the nozzle | cap | die parts 4 of this bottle can body 5, it is a can axis direction sequentially to this diameter-expanded part. The diameter is reduced by shifting the processing position upward to form a bottle can body 5 shown in FIG.

  The base part 4 of the bottle can body 5 is connected to the upper end of the base part 4a of the base part 4a in the can axis direction and bulges outward in the radial direction. A male thread formation planned portion 4c extending upward, and a curl formation planned portion 4d having a diameter smaller than that of the planned molding portion 4c are provided continuously to the upper end of the male screw formation planned portion 4c. In addition, the upper end portion in the can axis direction of the lower part 4a of the base part is a neck part formation planned part 4e having a smaller diameter than the skirt formation planned part 4b.

  Thereafter, as shown in FIG. 8, the spiral male screw portion 6 is formed on the male screw molding scheduled portion 4 c of the base portion 4 of the bottle can body 5, and the inner surface of the skirt molding planned portion 4 b is radially outward. After forming the skirt portion 112 by pressing it toward the other side, the curled portion 4d is bent radially outward to form the curled portion 8 to form the bottle can 110 having the base portion 111. . As shown in FIG. 8, the skirt portion 112 has a first peripheral wall portion 112 a that gradually increases in diameter toward the lower side in the can axis direction, and a convex curved surface that protrudes radially outward at the lower end of the first peripheral wall portion 112 a. It is set as the schematic structure provided with the 2nd surrounding wall part 112c continuously provided through the part 112b and gradually diameter-reduced as it goes below.

In the skirt portion 112, conventionally, only the molding target portion of the convex curved surface portion 112b of the inner surface of the skirt molding planned portion 4b is pressed outward in the radial direction. Each of the first peripheral wall portion 112a and the second peripheral wall portion 112c is deformed so as to follow the deformation toward the front, and is formed into the first peripheral wall portion 112a and the second peripheral wall portion 112c, and the skirt portion 112b is formed. Has been. Moreover, about the apparatus and method which shape | mold the external thread part 6, the structure shown by the following patent document 1 is known, for example.
JP 2002-219539 A

  In the above configuration, the size a of the skirt portion 112 in the can axis direction is not constant in the circumferential direction due to the spiral shape of the male screw portion 6, and as shown in FIG. The portion (hereinafter referred to as “circumferential position A”) located at the end portion 6a at the lower end is the smallest, and gradually increases from this position A toward the direction X in which the male screw portion 6 extends in the circumferential direction. And this magnitude | size a becomes the largest in the part located in the vicinity (henceforth "the circumferential direction position B") on the opposite side to the said extending direction X of the said end part 6a of the external thread part 6. FIG. Specifically, among the first peripheral wall portion 112a, the convex curved surface portion 112b, and the second peripheral wall portion 112c constituting the skirt portion 112, only the size in the can axis direction of the first peripheral wall portion 112a is the aforementioned in the circumferential direction. So different.

  Due to the difference in the size a in the circumferential direction of the skirt portion 112, it is difficult to form the skirt portion 112 with high accuracy over the entire circumference in the conventional method for forming the skirt portion. There was a problem that there was. Specifically, the radius of curvature R of the skirt portion 112 (convex curved surface portion 112b) at the circumferential position A and the skirt angle (the outer peripheral surface of the second peripheral wall portion 112c or its tangent line are perpendicular to the can axis. Angle) θ is formed with the smallest and highest accuracy in the skirt portion 112, and gradually increases as the male screw portion 6 moves in the extending direction X. There is a problem that the molding is performed at the position B with the greatest accuracy.

  In such a bottle can with a cap in which the cap is screwed to the bottle can 110, when the cap is loosened, the bridge of the cap disposed on the skirt portion 112 of the bottle can 110 cannot be broken well, and the cap It is difficult to reseal the bottle can 110 again because the flare is opened with the diameter expanded.

  Further, due to the difference in the dimensions of the radius of curvature R and the skirt angle θ in the circumferential direction of the bottle can 110, the buckling strength at the skirt portion 112 of the base portion 111 of the bottle can 110 has a circumferential strength of the bottle can 110. The capping process of screwing the cap onto the base part 111 after filling the bottle can 110 with the contents may cause the screwing accuracy of the cap to the base part 111 to vary depending on the circumferential position. was there.

  That is, in the capping step, when the cap is put on the base 111 of the bottle can 110 and then the outer peripheral edge of the cap top plate is pressed downward in the can axis direction over the entire circumference, the skirt Of the portion 112, the portion where R and θ are large has a high buckling strength, so that the shape is maintained, whereas the portion where R and θ are small has a low buckling strength, so the skirt portion 112 is in the can axis direction. The cap part 111 may be deformed so as to be crushed downward, and the base part 111 may be inclined with respect to the can axis. Therefore, in the circumferential direction of the bottle can with a cap, for example, there is a possibility that high sealing performance is realized in a portion where R and θ are large, and high sealing performance is not obtained in a portion where R and θ are small.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a bottle can that can form a skirt portion with high accuracy in a base portion.

  In order to solve such problems and achieve the above object, the bottle can of the present invention is a bottle can in which a cap is screwed to a base part, and the base part includes a male screw part and the male screw. A first peripheral wall portion that is continuously provided at the lower end of the can axis direction and gradually increases in diameter toward the lower side, and a convex curved surface portion that protrudes radially outward at the lower end of the first peripheral wall portion. And a skirt portion having a second peripheral wall portion gradually reduced in diameter as it goes downward, and from the end portion at the lower end in the can axis direction of the male screw portion of the first peripheral wall portion, Radially inwardly extending in the circumferential direction or intermittently interspersed in the circumferential direction at a portion located in a region of at least about 180 ° in the direction opposite to the direction in which the male screw portion extends. It is characterized in that a concave portion is formed.

  According to the present invention, since the concave portion is formed in the portion of the first peripheral wall portion that is located in the region, it is possible to suppress the shape of the skirt portion that is located in this region from sagging.

  That is, out of the inner surface of the molding target portion of the skirt portion, the outer surface of the molding target portion of the first peripheral wall portion has a diameter while pressing the molding target portion of the convex curved surface portion radially outward to mold the skirt portion. When the concave portion is formed by pressing inward in the direction, it is possible to prevent the pressing force applied to the inner surface of the portion to be molded of the convex curved surface portion from being distributed upward in the can axis direction from the concave portion. Become. Therefore, it becomes possible to concentrate this pressing force on the respective molding scheduled portions of the first peripheral wall portion, the convex curved surface portion and the second peripheral wall portion located below the concave portion, and the curvature radius of the convex curved surface portion, In addition, the skirt portion can be formed by setting the angle formed by the outer surface of the second peripheral wall portion or the tangent line thereof to the direction perpendicular to the can axis over the entire circumference.

  In addition, after forming the skirt portion, when the outer surface of the first peripheral wall portion is pressed radially inward to form the concave portion, the radius of curvature of the convex curved surface portion located in the region is large, and the skirt portion is slanted. Even when it occurs, when the concave portion is formed by pressing, the portion located below the concave portion of the first peripheral wall portion is tilted toward the radially inner side with the convex curved surface portion as a fulcrum, It becomes possible to reduce the curvature radius of the convex curved surface portion. Therefore, it is possible to form a skirt portion in which the curvature radius of the convex curved surface portion is substantially uniform over the entire circumference.

  As described above, when the cap is loosened, the cap bridge arranged in the skirt portion of the bottle can cannot be broken well, the cap flare is opened with the diameter expanded, and the bottle can is resealed again. This makes it difficult to suppress the screwing accuracy of the cap with respect to the cap portion at each circumferential position in the capping step.

  By the way, the bottle can after the contents are filled, the cap is screwed to the cap portion, and at this time, the flare as the free end portion of the cap is skirted by the skirt winding roll. It is molded by pressing inward in the radial direction so as to follow the outer shape of the part. The position in the can axis direction at the time of molding of the skirt roll used at the time of molding with respect to the arranged bottle cans is generally set as follows.

  First, the cap part of the bottle can is imaged from the side by an imaging means to capture the contour line of the cap part, and in the contour line, the extension line in contact with the second peripheral wall part and the convex curved surface part are in contact with each other. An intersection point between the can axis and a straight line parallel to the can axis is specified, and a distance in the can axis direction between the intersection point and the opening end face of the base part is measured. And based on this measured value, the can axial direction position at the time of the said shaping | molding of the said tail winding roll is set.

  Such a setting method has a problem that it is difficult to set the position of the tail winding roll with high accuracy. That is, the distance in the radial direction between the convex curved surface portion and the lower end portion in the can axis direction of the second peripheral wall portion is generally only about 1.2 mm, and the second peripheral wall portion has both end portions in the can axis direction. It is a curved surface shape, and the straight portion is only about 0.3 mm to 0.6 mm. Therefore, in the setting method as described above, there is a problem that it is difficult to specify the extension line in contact with the second peripheral wall portion with high accuracy.

  However, in the bottle can according to the present invention, since the concave portion is formed in the first peripheral wall portion, the intersection of the extension line in contact with the second peripheral wall portion and the straight line parallel to the can axis in contact with the convex curved surface portion is specified. In place of measuring the distance in the can axis direction between the intersection and the opening end face in the base part, the setting is performed by measuring the distance in the can axis direction between the concave part and the opening end face of the base part. It becomes possible. Therefore, since the recessed portion can be specified more easily than the extension line in contact with the second peripheral wall portion, the setting can be performed easily and with high accuracy. Furthermore, this measurement is not limited to the method based on the contour line, and can be performed by, for example, a contact method. By adopting this contact method, this measurement can be performed with higher accuracy. Can do. By the above, the can axial direction position at the time of shaping | molding a tail roll can be set easily and with high precision.

Here, the said recessed part may be formed in the said 1st surrounding wall part in the position away 0.5 mm or more and 2 mm or less toward the can axial direction upper direction from the radial direction outer end part of the said convex curved surface part.
In this case, the above-described effects can be reliably achieved.

  Moreover, the said recessed part may be formed over the perimeter in the part located in a can axial direction downward direction from the said end part of the said external thread part among the said 1st surrounding wall parts.

  When the concave portion is formed on the entire circumference of the first peripheral wall portion, the bottle can is positioned in the circumferential direction when setting the can axial direction position of the hem roll in the molding with respect to the arranged bottle can as described above. This eliminates the need to do so, so that the efficiency of this setting can be further increased.

  According to this invention, a skirt part can be shape | molded with high precision in a nozzle | cap | die part.

Embodiments of the present invention will be described below with reference to the drawings. First, a schematic configuration of a bottle can shown as an embodiment of the present invention will be described.
As shown in FIG. 1, the bottle can 20 has a large-diameter body portion (not shown) and a shoulder portion 23 that is connected to the upper end of the body portion in the can axis direction and is gradually reduced in diameter as it goes upward. And a base portion 22 that is provided continuously with the upper end of the shoulder portion 23 and extends upward. The base part 22 has a curled part 8 formed by bending an opening end part radially outward, a male screw part 6 extending spirally in the circumferential direction at the center part in the can axis direction of the base part 22, and the male screw. A skirt portion 7 is formed which is connected to the lower end in the can axis direction of the portion 6 and bulges outward in the radial direction.

  As shown in FIG. 2, the skirt portion 7 is connected to the lower end of the male screw portion 6 in the can axis direction, and is connected to the first peripheral wall portion 7 a gradually enlarged in diameter toward the lower side, and the lower end of the first peripheral wall portion 7 a. A convex curved surface portion 7b that is convex outward in the radial direction, and a second peripheral wall portion 7c that is connected to the lower end of the convex curved surface portion 7b and is gradually reduced in diameter as it goes downward. A neck portion 9 having a smaller diameter than the convex curved surface portion 7b and extending downward is continuously provided at the lower end of the second peripheral wall portion 7c, that is, the lower end of the skirt portion 7.

  In the above configuration, the size a of the skirt portion 7 in the can axis direction is not constant in the circumferential direction due to the spiral shape of the male screw portion 6, and as shown in FIG. The portion (hereinafter referred to as “circumferential position A”) located at the end portion 6a at the lower end is the smallest, and gradually increases from this position A toward the direction X in which the male screw portion 6 extends in the circumferential direction. And this magnitude | size a is the largest in the part located in the vicinity (henceforth "the circumferential position B") on the opposite side to the said extending direction X of the said end part 6a of the external thread part 6. FIG. .

  Specifically, among the first peripheral wall portion 7a, the convex curved surface portion 7b, and the second peripheral wall portion 7c constituting the skirt portion 7, only the size in the can axis direction of the first peripheral wall portion 7a is as described above in the circumferential direction. In contrast, the size of the convex curved surface portion 7b and the second peripheral wall portion 7c in the can axis direction is uniform over substantially the entire circumference of the base portion 22.

  The first peripheral wall portion 7a has an end portion 6a at the lower end in the can axis direction of the male screw portion 6 in a region at least about 180 ° in a direction opposite to the direction X in which the male screw portion 6 extends in the circumferential direction. In the present embodiment, a recessed portion 7d extending in the circumferential direction is formed over the entire periphery of the first peripheral wall portion 7a in the portion that is positioned. Further, the distance between the concave portion 7d and the convex curved surface portion 7b in the can axis direction is substantially equal over the entire circumference of the base portion 22. Further, as shown in FIG. 1, the concave portion 7 d of the present embodiment is formed on the entire circumference of a portion of the first peripheral wall portion 7 a located below the end portion 6 a of the male screw portion 6 in the can axis direction. It is formed continuously.

  Further, as shown in FIG. 2, the concave portion 7d of the present embodiment is a concave groove that is concaved by being curved inward in the radial direction only on the outer peripheral surface of the first peripheral wall portion 7a, and corresponds to this position. The inner peripheral surface is a smooth surface. In addition, the recessed part 7d is formed in the position which was 0.5 mm or more and 2 mm or less away from the radial direction outer end part of the convex-curved surface part 7b above the can axis direction. The size of the concave portion 7d in the can axis direction is 0.2 mm or less, and the radial direction between the outer peripheral surface of the first peripheral wall portion 7a and the outermost surface of the concave portion 7d that is located at the most radially inner side. The distance, that is, the depth of the recess 7d is 0.02 mm to 0.10 mm.

  Next, a bottle can manufacturing apparatus for forming the male screw part 6, the skirt part 7, and the neck part 9 of the bottle can 20 configured as described above will be described. Since the bottle can body 5 used in this manufacturing apparatus is the same as the conventional one shown in FIG. 7, the description thereof is omitted.

  As shown in FIGS. 3 to 5, the bottle can manufacturing apparatus 10 according to the present embodiment includes an inner molding piece 60 disposed inside the bottle can body cap portion 4 and an outer molding piece 50 disposed outside. Each of these molding pieces 60, 50 includes a skirt molding part 12a, 12b and a male screw molding part 11a, 11b arranged coaxially with the skirt molding part 12a, 12b. In each molding piece 60, 50, the lower part in the axial direction is the skirt molding parts 12a, 12b, and the upper part is the male screw molding parts 11a, 11b. Further, the molding pieces 60 and 50 are supported so as to be able to approach and separate in the can axis direction and the radial direction with respect to the cap portion 4 of the bottle can body 5 arranged, and are supported so as to be rotatable around their respective rotation axes. Has been.

  Here, for convenience of the following description, the skirt molding portion 12a of the inner molding piece 60 is referred to as “inner skirt molding portion 12a”, and the male screw molding portion 11a of the inner molding piece 60 is referred to as “inner male screw molding portion 11a”. The skirt molding portion 12b of the outer molding piece 50 is referred to as “outer skirt molding portion 12b”, and the male screw molding portion 11b of the outer molding piece 50 is referred to as “outer male screw molding portion 11b”.

  From the above, as shown in FIG. 5, after the inner molding piece 60 is arranged inside the base portion 4 and the outer molding piece 50 is arranged outside, the respective molding pieces 50, 60 move closer to each other. By doing so, the male screw part 6, the skirt part 7 and the neck part 9 are formed in the base part 4 by rotating these 50 and 60 around the can axis in a state where the base part 4 is sandwiched. It has become.

  Here, on the outer peripheral surfaces of the inner and outer male screw forming portions 11a and 11b, respectively, outward in the radial direction of the respective forming portions 11a and 11b, as shown in FIG. The convex male screw pressing portions 11c and 11d are formed in a spiral shape so that their positions in the axial direction are shifted. And the magnitude | size in the radial direction from the outer peripheral surface of the external thread molding part 11a, 11b of each external thread press part 11c, 11d of this embodiment, ie, thread height D, C, is the thread height of the external thread part 6 to shape | mold. It is larger than E.

  Thereby, at the time of shaping | molding of the external thread part 6, the outer peripheral surface of the outer side male screw molded part 11b and the outer peripheral surface of the screw thread part 6c of the external thread part 6 are made non-contact, and the outer peripheral surface of the inner side male screw molded part 11a and an external thread part The inner peripheral surface of the sixth trough portion 6b is not in contact.

  The outer skirt forming portion 12b includes an outer pressing portion 102d that presses the outer surface of the neck portion forming planned portion 4e inward in the radial direction, at least a part of the first peripheral wall portion 7a, the convex curved surface portion 7b, and the second peripheral wall portion. 7c, a region of at least about 180 ° directed from the end portion 6a at the lower end in the can axis direction of the male screw portion 6 to be molded in the direction opposite to the direction X (see FIG. 1) in which the male screw portion 6 extends in the circumferential direction. When forming a portion located in (hereinafter referred to as "region"), at least a part of the first peripheral wall portion 7a, the outer surfaces of the respective planned forming portions of the convex curved surface portion 7b and the second peripheral wall portion 7c are pressed, And a support portion 12c for supporting these 7a, 7b and 7c.

  In the support portion 12c of the present embodiment, the lower surface in the can axis direction of the first peripheral wall portion 7a, and the outer surfaces of the respective molding scheduled portions of the convex curved surface portion 7b and the second peripheral wall portion 7c are pressed substantially continuously in the can axis direction. These 7a, 7b and 7c are configured to be supported, and the outer pressing portion 102d is smoothly connected to the lower end in the axial direction.

  Further, the outer skirt forming portion 12b of the present embodiment includes a first convex curved surface portion 12d that is connected to the upper end in the axial direction of the support portion 12c and gradually decreases in diameter as it goes upward in the axial direction. In addition, the connection part 12g with the support part 12c of the 1st convex curved surface part 12d is made convex in the curved surface shape to radial direction outward, and the curvature radius is about 0.5 mm-2.0 mm.

  As described above, when the skirt portion 7 is formed, the lower surface of the first peripheral wall portion 7a, the convex curved surface portion 7b, and the second peripheral wall portion 7c are to be formed by pressing their outer surfaces against the support portion 12c. It has come to be. In other words, the inner surface of the lower part of the first peripheral wall part 7a, the inner curved surfaces of the convex curved surface part 7b and the second peripheral wall part 7c are pressed radially outward by the inner skirt forming part 12a, which will be described later. The corresponding outer surface is pressed against and supported by the outer surface of the support portion 12c. The upper end portion of the lower outer surface of the part to be molded of the first peripheral wall portion 7a is pressed radially inward by the connecting portion 12g of the first convex curved surface portion 12d.

  The inner skirt molding portion 12a of the present embodiment is a first inner pressing portion that presses the inner surface of each first molding portion of the first peripheral wall portion 7a and the projected curved surface portion 7b toward the radially outer side. 12e and a bent portion 12f that bends the portion to be molded of the second peripheral wall portion 7c from the inner surface side toward the radially outer side with the lower end portion in the can axis direction as a fulcrum. The first inner pressing portion 12e and the bent portion 12f are connected smoothly in the axial direction.

  In this embodiment, the 1st inner side press part 12e and the bending part 12f are formed over the perimeter on the outer peripheral surface of the inner side skirt shaping | molding part 12a. Further, in the present embodiment, the inner skirt molding portion 12a includes a second inner pressing portion 12h that presses the inner surface of the first circumferential wall portion 7a in the can axis direction upper portion of the molding scheduled portion radially outward.

Next, a method for forming the male screw part 6, the skirt part 7 and the neck part 9 in the bottle can body cap part 4 by the bottle can manufacturing apparatus 10 configured as described above will be described.
First, as shown in FIG. 4, after holding the bottle can body 5 on a holding table (not shown) in a state where the can axis and the center axis O of the apparatus 10 coincide with each other, the outer forming piece 50 and the inner forming piece 60 are moved. Move forward toward the bottle can body 5.

  Here, the rotational axis of the inner molding piece 60 substantially coincides with the central axis O of the apparatus 10, and the outer diameter of the inner molding piece 60 is made smaller than the inner diameter of the bottle can body cap 4. 50 is located at a position where the distance between the rotation axis and the outer peripheral surface of the bottle can body mouthpiece 4 is larger than the radius of the outer molding piece 50. From the above, the apparatus 10, that is, the inner molding piece 60 and When the outer molding piece 50 is moved forward in the direction of the can axis toward the bottle can body 5, the inner molding piece 60 is disposed inside the bottle can body base portion 4, and the outer molding piece 50 is placed on the bottle can base portion 4. Arranged outside.

  Thereafter, the driving means (not shown) moves the inner molding piece 60 radially outward of the bottle can body 5, and moves the outer molding piece 50 radially inward of the bottle can body 5, By moving the molding pieces 50 and 60 in the direction in which they approach each other, the base 4 is sandwiched between the outer surfaces of the molding pieces 50 and 60 as shown in FIG. Of the base part 4, the male thread forming part 4c is sandwiched between the inner and outer male thread forming parts 11a and 11b, and the skirt forming part 4b is sandwiched between the inner and outer skirt forming parts 12a and 12b.

  Among these, the male screw molding scheduled portion 4c has its inner surface pressed radially outward by the male screw pressing portion 11c of the inner male screw molding portion 11a to form the screw thread portion 6c and the outer surface thereof. The trough portion 6b is formed by being pressed radially inward by the male screw pressing portion 11d of the outer male screw forming portion 11b. Further, at this time, the inner peripheral surface of the valley portion 6b is not in contact with the outer peripheral surface of the inner male screw forming portion 11a, and the outer peripheral surface of the screw thread portion 6c is not in contact with the outer peripheral surface of the outer male screw forming portion 11b. Is done.

  On the other hand, of the inner surface of the skirt molding planned portion 4b, the lower portion in the can axis direction of the first peripheral wall portion 7a and the respective molding planned portions of the convex curved surface portion 7b are changed in diameter by the first inner pressing portion 12e of the inner skirt molding portion 12a. The portion to be molded of the second peripheral wall portion 7c is pressed radially outward from the inner surface side by the bent portion 12f of the inner skirt molding portion 12a with the lower end portion as a fulcrum. It can be bent. Further, the upper inner surface in the can axis direction of the part to be molded of the first peripheral wall part 7a is pressed radially outward by the second inner pressing part 12h of the inner skirt molding part 12a.

  Further, the lower end portion in the can axis direction of the outer surface of the planned skirt molding portion 4b in the molding target portion of the second peripheral wall portion 7c is pressed radially inward by the outer pressing portion 102d of the outer skirt molding portion 12b. At the same time, the lower part of the first peripheral wall part 7a in the can axis direction, the convex curved surface part 7b, and the respective part to be formed of the second peripheral wall part 7c are pressed against and supported by the support part 12c of the outer skirt molding part 12b. That is, due to the radially outward pressing by the first inner pressing portion 12e of the inner skirt forming portion 12a, the lower portions of the first peripheral wall portion 7a, the convex curved surface portion 7b, and the second peripheral wall portion 7c are to be formed. The outer surface of substantially the entire region is pressed against and supported by the support portion 12c.

  At this time, the upper end portion of the outer surface of the first circumferential wall portion 7a at the lower portion in the can axis direction, that is, the lower position in the can shaft direction from the end portion 6a of the male screw portion 6, is the first convex curved surface portion of the outer skirt molding portion 12b. It is pressed inward in the radial direction by the connecting portion 12g of 12d. In addition, the neck molding scheduled portion 4e is connected to the lower end of the bent portion 12f of the inner skirt molded portion 12a in a state where the inner surface thereof is unconstrained, and the neck molding planned portion 4e is connected to the outer pressing portion 102d. The outer surface is pressed inward in the radial direction by the outer pressing portion 102d in a state where it is not in contact with the outer surface of the portion 101d facing each other.

As described above, the apparatus 10 is rotated around the central axis O in a state where the bottle can body cap portion 4 is sandwiched between the outer and inner molding pieces 50 and 60, so that the entire periphery of the cap portion 4 is provided. As a result, the male screw portion 6, the skirt portion 7, and the neck portion 9 are formed. In this molding process, the upper end portion of the lower outer surface of the portion to be molded of the first peripheral wall portion 7a is directed radially inward by the connecting portion 12g of the first convex curved surface portion 12d over the entire circumference. By being pressed, on the outer peripheral surface of the first peripheral wall portion 7a, the entire circumference of the male screw portion 6 is located below the end portion 6a of the male screw portion 6 as shown in FIG. 1 and FIG. Thus, a concave portion 7d extending continuously is formed.
Thereafter, the opening end of the bottle can base 4 is folded outward in the radial direction to form the curled portion 8, and the bottle can 20 shown in FIGS. 1 and 2 is formed.

  As described above, according to the bottle can according to the present embodiment, since the concave portion 7d is formed in the portion of the first peripheral wall portion 7a located in the region, the shape of the skirt portion 7 located in this region is It is possible to suppress drooling.

  That is, in the present embodiment, of the inner surface of the skirt portion molding planned portion 4b, the molding portion of the convex curved surface portion 7b is pressed radially outward to mold the skirt portion 7, while the first circumferential wall portion 7a Since the concave portion 7d is formed by pressing the outer surface of the planned molding portion radially inward, the pressing force applied to the inner surface of the planned molding portion of the convex curved surface portion 7b is higher in the can axis direction than the concave portion 7d. It becomes possible to prevent dispersion toward

  Therefore, this pressing force can be applied intensively to the respective planned molding portions of the first peripheral wall portion 7a, the convex curved surface portion 7b, and the second peripheral wall portion 7c located below the concave portion 7d. The skirt portion 7 can be formed so that the radius of curvature R of 7b and the angle θ formed by the outer surface of the second peripheral wall portion 7c or the tangent line thereof in a direction perpendicular to the can axis are substantially uniform over the entire circumference. it can.

  As a result, when the cap is loosened, the bridge of the cap arranged in the skirt portion of the bottle can cannot be broken well, and the cap flare is opened with the diameter expanded, and the bottle can is resealed again. This makes it difficult to suppress the screwing accuracy of the cap with respect to the cap portion at each circumferential position in the capping step.

  Moreover, since the recessed part 7d is formed in the 1st surrounding wall part 7a, when setting the can axial direction position at the time of shaping | molding with respect to the arrange | positioned bottle can 20 of the skirt winding roll, the nozzle | cap | die part 22 of the bottle can 20 is the The image is picked up by the imaging means from the side surface, the outline of the base portion 22 is captured, and the setting is performed by measuring the distance in the can axis direction between the concave portion 7d and the opening end face of the base portion 22 at the outline. It becomes possible to implement, and this setting can be implemented easily and with high precision. In addition, this measurement is not limited to the method based on the contour line, and can be performed by, for example, a contact method. By adopting this contact method, this measurement can be performed with higher accuracy. it can.

  Further, in the present embodiment, the concave portion 7d is continuously formed over the entire circumference of the first peripheral wall portion 7a at a portion located below the end portion 6a of the male screw portion 6 in the can axis direction. Therefore, it is not necessary to position the bottle can 20 in the circumferential direction when setting the position of the skirt winding roll in the can axis direction at the time of molding with respect to the arranged bottle can 20 as described above. Can be further improved in efficiency.

  Further, since the recess 7d is formed at a position away from the radially outer end of the convex curved surface portion 7b in the first peripheral wall portion 7a by 0.5 mm or more and 2 mm or less upward in the can axis direction, The effect is surely achieved.

  Moreover, according to the manufacturing method of the bottle can by this embodiment, from the end part 6a of the lower end of the can screw direction of the external thread part 6 as a part with a large magnitude | size in the can axis direction among the skirt parts 7, it can go to the circumferential direction. When forming a portion located in an area of at least about 180 ° in the direction opposite to the direction X in which the male screw portion 6 extends, of the skirt portion formation planned portion 4b, Since not only the surface but also the inner surface of the portion to be molded of the first peripheral wall portion 7a is pressed outward in the radial direction, it is possible to prevent the shape of the skirt portion 7 located in the region from falling.

  That is, only the inner surface of the portion to be molded of the convex curved surface portion 7b is pressed outward in the radial direction, and the first peripheral wall portion 7a is scheduled to be deformed in the deformation behavior toward the radially outer side of the convex curved surface portion 7b. Instead of forming the first peripheral wall portion 7a by deforming it so as to follow the portion, the inner surface of the part to be formed of the first peripheral wall portion 7a is positively pressed radially outward in this direction. Since the first peripheral wall portion 7a is formed by being deformed, even if the pressing is released after the molding, the shape at the time of pressing does not occur in the first peripheral wall portion 7a without causing a springback directed radially inward. Can be maintained. Accordingly, the skirt portion 7 is formed so that the radius of curvature R of the convex curved surface portion 7b and the angle θ formed by the outer surface of the second peripheral wall portion 7c or the tangent line thereof in the direction perpendicular to the can axis are substantially equal over the entire circumference. Can be molded.

  Further, when molding a portion of the skirt portion 7 located in the region, an inner surface corresponding to the outer surface is formed in a state where the molding target portion of the first peripheral wall portion 7a is supported from the outer surface side by the support portion 12c. Since it is pressed radially outward by the first inner pressing portion 12e and is formed on the first peripheral wall portion 7a of the skirt portion 7, it is generated on the outer surface of the portion to be formed of the first peripheral wall portion 7a during this forming. The extension in the can axis direction can be suppressed, and this extension reliably prevents the deformation of the first peripheral wall portion 7a toward the outside in the radial direction or the occurrence of the spring back. Can be prevented.

  Further, when the skirt portion 7 located in the region is formed, the molding target portion of the second peripheral wall portion 7c is bent, so that the lower end portion in the can axis direction of the second peripheral wall portion 7c to be formed can be work-hardened. Become. Therefore, when the first circumferential wall portion 7a and the convex curved surface portion 7b are released from the radially outward press against the inner surfaces of the respective molding scheduled portions, the first circumferential wall portion 7a and the convex curved surface portion 7b are radially inward. Even when a springback directed toward the direction is about to occur, the lower end portion in the can axis direction of the work-cured second peripheral wall portion 7b can be made to act as a reinforcing portion that resists this springback. Become.

  Further, when the portion of the skirt portion 7 located in the region is formed, the inner surface corresponding to the outer surface is radially outward in a state in which the forming portion of the convex curved surface portion 7b is supported from the outer surface side. Is formed into the convex curved surface portion 7b, and during this molding, it is possible to suppress the extension in the can axis direction that occurs on the outer surface of the portion to be molded of the convex curved surface portion 7b. When the deformation toward the outside in the radial direction of the part to be molded of the convex curved surface part 7b is inhibited, or when the pressing toward the outside in the radial direction against the inner surface of the part to be molded of the convex curved part 7b is released, It is possible to reliably suppress the occurrence of a spring back directed radially inward on the convex curved surface portion 7b.

  In addition, since the part to be molded of the second peripheral wall part 7c is bent while being supported from the outer surface side, it is generated on the outer surface of the lower end part of the part to be molded of the second peripheral wall part 7c during the molding. In addition, it becomes possible to suppress the compressive strain along the extending direction of the longitudinal cross-sectional shape, and when the bending of the second peripheral wall portion 7c after the molding is released after the molding, the second peripheral wall portion 7c is caused by the compressive strain. Can be prevented from springing back upward in the can axis direction.

  Furthermore, in this embodiment, when forming the recessed part 7d in the 1st surrounding wall part 7a, the outer surface of this surrounding wall part 7a is radial inside by the said connection part 12g of the 1st convex curved surface part 12d of the outer side skirt shaping | molding part 12b. The inner surface corresponding to the inner surface is pressed radially outward by the first inner pressing portion 12e of the inner skirt molding portion 12a, and the inner and outer surfaces are firmly clamped. It becomes.

  Therefore, in combination with the work hardening of the lower end portion of the second peripheral wall portion 7c as described above, the inner surfaces of the respective planned forming portions of the first peripheral wall portion 7a and the convex curved surface portion 7b when the skirt portion 7 is formed. It is possible to prevent the pressing force directed radially outward with respect to the can axis direction above the recess 7d and below the lower end portion of the second peripheral wall portion 7c. It can be applied intensively to the lower portion of the first peripheral wall portion 7a located between the concave portion 7d and the lower end portion of the second peripheral wall portion 7c and to the respective molding scheduled portions of the convex curved surface portion 7b. Therefore, the skirt portion 7 can be formed with higher accuracy.

  Furthermore, when forming the male screw portion 6 in the male screw forming portion 4c, the inner peripheral surface of the valley portion 6b and the outer peripheral surface of the screw thread portion 6c are not in contact with the male screw forming portions 11a and 11b. It is possible to prevent the male screw portion 6 from being compressed and deformed in the thickness direction at the time of molding and to reduce its thickness, and to prevent the buckling strength of the male screw portion 6 from being lowered.

  Here, when the inner peripheral surface of the valley portion 6b of the male screw portion 6 and the outer peripheral surface of the screw thread portion 6c are not in contact with each other in this manner and the male screw portion 6 is formed, the non-contact area is obtained. Since the restraint of the molding pieces 50 and 60 by the bottle can body base part 4 is loosened by the increase, the inclination of the rotation axis of the molding pieces 50 and 60 is the circumferential position of the base part 4 at the time of molding. As a result, the thread height E may not be stable at each circumferential position, and it may be difficult to form the highly accurate male thread portion 6.

  However, in the present embodiment, the male screw portion 6 is molded in a state where the lower portion of the first peripheral wall portion 7a, the inner and outer surfaces of the convex curved surface portion 7b, and the second peripheral wall portion 7c are sandwiched by the molding pieces 50 and 60. Therefore, it becomes possible to ensure the necessary and sufficient restraint of the molding pieces 50 and 60 by the bottle can body base part 4, and the inclination of the rotation axis at the time of molding varies for each circumferential position of the base part 4. It becomes possible to suppress this. Therefore, it is possible to suppress variations in the circumferential position of the thread height E, and the highly accurate male thread portion 6 can be formed.

  In particular, in the present embodiment, the male threaded portion 6 is formed while the skirt portion 7 is being molded while the portion to be molded of the second peripheral wall portion 7c is bent from the inner surface side radially outward with the lower end portion in the can axis direction as a fulcrum. Since each skirt molding portion 12a, 12b is in surface contact with the inner and outer surfaces of the second peripheral wall portion 7c, the skirt molding portions 12a, 12b are inclined with respect to their respective rotation axes during molding. By the surface contact, it becomes possible to prevent the occurrence of this inclination by the frictional force generated between the bottle can body base part 4 and the respective molding pieces 50, 60, and the highly accurate male screw part 6 can be surely provided. Can be molded.

  Here, among the above-described effects, an evaluation test was conducted on the ability to form the skirt portion 7 with high accuracy. As an evaluation method, 20 bottle cans 20 shown in FIG. 1 are prepared, and for each bottle can 20, the skirt angle θ (see FIG. 1) is set at three locations in the skirt portion 7 at arbitrarily different positions in the circumferential direction. It was measured. As a comparative example, a skirt angle θ was measured in the same manner using a bottle can 110 shown in FIG.

  As a result, in the comparative example, the standard deviation of the angle θ is 3.398, whereas in the bottle can 20 of the present embodiment, it is 1.549, and in the example, the skirt portion 7 can be formed with high accuracy. confirmed.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the embodiment, as shown in FIG. 2, the recess 7 d is a concave groove that is recessed in a curved shape radially inward only on the outer peripheral surface of the first peripheral wall portion 7 a, and the inner peripheral surface corresponding to this position is Although the structure having a smooth surface is shown, the concave portion 7d may be formed by denting not only the outer peripheral surface of the first peripheral wall portion 7a but also the inner peripheral surface inward in the radial direction. Further, instead of the concave portion 7d shown in FIG. 2, the shape of the longitudinal sectional view may be a V shape, for example, and is not limited to these shapes.

  Furthermore, the concave portion 7d is continuously formed over the entire circumference of the first peripheral wall portion 7a in a portion located below the end portion 6a of the male screw portion 6 in the can axis direction. If it forms in the part located in a 180 degree area | region, the formation position in the can axial direction will not be specifically limited. Moreover, you may form the recessed part 7d by making it disperse | distribute intermittently to the 1st surrounding wall part 7a in the circumferential direction. Furthermore, although the recessed part 7d was formed in the 1st surrounding wall part 7a in the perimeter, it should just be formed in the part located in the said 180 degree area | region at least.

  In the above embodiment, the concave portion 7d is formed at the same time as the skirt portion 7 is molded. However, after the skirt portion 7 is molded, the outer surface of the first peripheral wall portion 7a is pressed inward in the radial direction. 7d may be formed. In this case, even when the curvature radius R of the convex curved surface portion 7b located in the region is large and the skirt portion 7 is bent, the first peripheral wall portion 7a is formed when the concave portion 7d is formed by pressing. Of these, a portion located below the concave portion 7d is tilted radially inward with the convex curved surface portion 7b as a fulcrum, and the radius of curvature R of the convex curved surface portion 7b can be reduced. Therefore, the skirt portion 7 can be formed by setting the curvature radius R of the convex curved surface portion 7b to a substantially uniform size over the entire circumference.

  Furthermore, in the said embodiment, when shape | molding the skirt part 7, not only the inner surface of the formation plan part of the convex-curved surface part 7b in the skirt part formation plan part 4b but the shaping | molding plan part of the 1st surrounding wall part 7a. Although the inner surface is also pressed outward in the radial direction, only the inner surface of the portion to be molded of the convex curved surface portion 7b may be pressed outward in the radial direction.

  Further, when molding the skirt portion 7 located in the region, the inner surface of the first peripheral wall portion 7a and the convex curved surface portion 7b is directed radially outward with the outer surface side supported. Although the first peripheral wall portion 7a and the convex curved surface portion 7b are formed by pressing, the inner surface may be pressed radially outward without supporting these outer surface sides.

  Furthermore, when the skirt portion 7 located in the region is molded, the molding portion of the second peripheral wall portion 7c is bent from the inner surface side while supporting the outer surface side to be molded into the second peripheral wall portion 7c. However, the inner surface side may be bent without supporting the outer surface side, or the inner and outer surfaces of the molding target portion are unconstrained, and the inner portions of the first peripheral wall portion 7a and the convex curved surface portion 7b are to be molded. The surface is pressed outward in the radial direction so that the molding target portion of the second peripheral wall portion 7c follows the deformation behavior of the first peripheral wall portion 7a and the convex curved surface portion 7b directed outward in the radial direction. The second peripheral wall portion 7c may be formed by deforming.

  Further, as shown in FIG. 6, the inner skirt forming portion 21 that does not have the bent portion 12f is adopted, the inner surface of the portion to be formed of the second peripheral wall portion 7c is made unconstrained, and the others are shown in FIG. The skirt portion 7 may be formed in the same manner as the form.

  Even in such a configuration, it was confirmed by the same evaluation method as described above that the standard deviation of the skirt angle θ was 1.671. Thereby, even if it employ | adopted the inner side skirt shaping | molding part 21 shown in FIG. 6, it has confirmed that it had an advantageous effect compared with the said comparative example.

  Further, in the above embodiment, the neck 9 is formed by pressing the outer surface of the neck portion 4e to be radially shaped inward without restricting the inner surface of the neck portion 4e, but it is positioned at least in the region of the skirt portion 7. When forming the portion, the neck portion 9e may be formed on the neck portion 9 by pressing the outer surface corresponding to the inner surface toward the radially inner side while supporting the neck portion forming portion 4e from the inner surface side.

  In this case, when the neck portion 9 is formed, it is possible to suppress the extension in the can axis direction that occurs on the inner surface of the neck portion formation planned portion 4e, and the deformation of the neck portion formation planned portion 4e directed radially inward by this extension. It is possible to prevent the neck portion 9 from springing back radially outward when the molding pieces 50, 60 are separated from the base portion 22 after molding. As a result, the neck portion 9 can be molded with high accuracy, the distortion of the shape of the neck portion 9 can be prevented from affecting the skirt portion 7, and the skirt portion 7 can be molded with high accuracy. This can be realized more reliably.

  Provided is a bottle can that can form a skirt portion with high accuracy in a base portion.

It is an enlarged side view which shows the bottle can shown as one Embodiment of this invention. It is F section expanded sectional view of the bottle can shown in FIG. It is a principal part expanded sectional view which shows one Embodiment of the apparatus which manufactures the bottle can shown in FIG. 1 and FIG. It is a schematic side view which shows the apparatus for manufacturing the bottle can shown as one Embodiment of this invention, Comprising: It is a figure which shows a 1st process. It is a schematic side view of the manufacturing apparatus of the bottle can shown in FIG. 4, Comprising: It is a figure which shows a 2nd process. It is a principal part expanded sectional view which shows other embodiment of the apparatus which manufactures the bottle can shown in FIG. 1 and FIG. It is process drawing which shows the process of forming a bottle can body from a bottomed cylindrical body. It is an enlarged side view which shows the bottle can of the prior art example which concerns on this invention.

Explanation of symbols

4 Bottle Can Body 5 Bottle Can Body 6 Male Threaded Part 6a End Part of Male Screw Part at Lower End in Can Axis 7 Skirt Part 7a First Peripheral Wall Part 7b Convex Curved Part 7c Second Peripheral Wall Part 20 Bottle Can 22 Cap of Bottle Can Part X Direction in which male thread extends

Claims (2)

A bottle can in which a cap is screwed onto a base part,
The base part is connected to the male screw part, the lower end of the male screw part in the can axis direction, and is gradually increased in diameter toward the lower side, and radially outward from the lower end of the first peripheral wall part. And a skirt portion provided with a second peripheral wall portion that is continuously reduced through a convex curved surface portion that is convex toward the bottom, and that is gradually reduced in diameter as it goes downward.
Of the first peripheral wall portion, from the end portion of the lower end of the male screw portion in the can axis direction, at a portion located in an area of at least about 180 ° in the direction opposite to the direction in which the male screw portion extends in the circumferential direction, A bottle can characterized in that a concave portion extending inward in the radial direction and extending in the circumferential direction or intermittently scattered in the circumferential direction is formed. The bottle can according to claim 1,
The concave portion is formed in the first peripheral wall portion at a position separated from the radial outer end of the convex curved surface portion by 0.5 mm or more and 2 mm or less upward in the can axis direction. Bottle can.

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