JP6512937B2 - Method and apparatus for forming curled portion of paper container - Google Patents

Description

  The present invention relates to a method and apparatus for forming a curl on the open edge of a paper container.

  The opening edge of the paper container is a curled portion for the purpose of improving the strength and the like. Patent Document 1 discloses a molding method for molding a curled portion at the opening edge. In this molding method, a pre-curl process and a finish curl process are performed.

  In the pre-curl process, a pre-curl mold having an annular pre-curl molding groove is used. By bringing the pre-curl mold close to the container along the central axis of the container, the pre-curl molded groove is pressed against the opening edge of the container, and the opening edge is folded outward to form a folded portion.

  In the above-mentioned finish curling step, a first finish die having an annular first molding groove disposed on the container side and a second finish die having an annular second molding groove are used. By bringing the second mold close to the first mold, the first molding groove and the second molding groove cooperate with each other to wind the folded portion inward to mold a curled portion.

  The pre-curl molding groove of the pre-curl mold has a uniform cross-sectional shape and depth over the entire circumference, like the first and second molding grooves of the first and second molds for finishing, The central axial position of the bottom of the container is constant over the entire circumference.

  Patent documents 2 and 3 disclose curl part molding methods of a type different from patent document 1. In the curl portion forming methods of these documents, the height of the opening edge of the intermediate-shaped container before forming the curl portion is different in the circumferential direction. Specifically, the large radius of curvature of the opening edge is high. This prevents the forming groove of the mold from striking the entire circumference of the opening edge simultaneously, and as a result, the processing load is reduced.

JP, 2004-330423, A Japanese Utility Model Publication No. 57-131410 Patent No. 4580500

In Patent Document 1, in the pre-curling step, the pre-curl forming groove simultaneously contacts the entire periphery of the opening edge of the container, and the folding is simultaneously started over the entire periphery, so a large processing load is applied to the container and the barrel Buckling may occur.
In the patent documents 2 and 3, although the device for avoiding that a big processing load is added to a container is made, it has the following fault. That is, the body of the general container has a tapered shape so as to expand toward the opening edge, and as shown in Patent Documents 2 and 3, a part of the opening edge extending from the body is When raised, the leading edge of this opening edge bulges radially. Therefore, the molding groove of the mold is forced to expand its width more than necessary in order to receive the radially protruding tip edge, and the curled part can not be formed well. In addition, since a part of the curling margin of the opening edge becomes wider than necessary, the curled part may be undulated or the curling thickness may become uneven.

The present invention has been made to solve the above-mentioned problems, and is a method of forming a curled portion on the opening edge of a paper container,
The pre-curl molding groove is pressed against the opening edge by bringing the pre-curl mold having an annular pre-curl molding groove close to the container along the central axis of the container, and the opening edge is folded outward. Pre-curl process for forming the folded portion
By bringing the second mold for finish curl having the annular second molding groove closer to the first mold for finish curl disposed on the container side and having the first molding groove having an annular shape, along the central axis, The first forming groove and the second forming groove cooperate with each other to wind the folded-back portion inward and form a curling portion;
The position of the central axis of the bottom surface of the forming groove for pre-curl changes along the circumferential direction, and the bottom surface of the pre-curl molding groove is the most projecting toward the container, and the bottom surface is the most retracted from the container. An area, and in the pre-curling step, the protruding area of the pre-curl forming groove is first pressed against a part of the opening edge, and the folding is started from the part of the opening edge. Do.
According to the above method, since the forming of the folded portion is started from a part of the opening edge, the pre-curling step can be started with a small processing load, and the buckling of the body of the container can be prevented.

Preferably, each of the first molding groove and the bottom surface of the second molding groove has a constant position in the central axis direction of the container over the entire circumference, and in the finish curling step, the second molding groove is The portion formed by the above-mentioned receding area at the turn-back portion is first pressed.
According to the above-described method, since a load is initially applied to a part of the folded portion even in the finish curling step, the processing load can be reduced. Further, since the positions of the bottom surfaces of the first and second forming grooves are respectively fixed, the curled portion can be made uniform in thickness over the entire periphery of the opening edge by the finish curling step.

Preferably, the pre-curl forming groove has an inclined region connecting the projecting region and the receding region, and in this inclined region, the bottom surface of the pre-curl forming groove is inclined with respect to a plane orthogonal to the central axis In the pre-curling step, the folding start position at the opening edge moves from the projecting area to the receding area via the inclined area.
According to the above method, since the start position of the folding of the opening edge starting from the projecting area of the pre-curl forming groove gradually shifts to the retreating area through the inclined area, it is possible to suppress the fluctuation of the processing load and stabilize Pre-curl molding can be performed.

The present invention can also provide a method of forming a curled portion by omitting the pre-curl process. That is, by bringing the second mold having the annular second molding groove close to the first mold having the annular first molding groove disposed on the paper container side along the central axis of the container. The second molding groove is pressed against the opening edge of the container and folded outward, and the curled portion is further wound inward by the cooperation of the first molding groove and the second molding groove. In the method of forming
In the second molding groove of the second mold, the position in the central axial direction of the bottom surface changes in the circumferential direction, and the bottom surface is the projecting region most projecting toward the container, and the bottom surface is the container Have the most retreated area from
In the process in which the first mold approaches the second mold, the projecting area of the second molding groove is first pressed against a portion of the opening edge, and the opening edge is viewed from the portion of the opening edge. It is characterized in that the folding to the outside of the part is started.

The present invention can also be applied to a method of forming a curled portion at the opening edge of a circular paper container. That is, the second mold having the annular second molding groove is brought close to the first mold having the annular first molding groove along the central axis of the container while being rotated while the second mold having the annular second molding groove is rotated. Thus, the opening edge portion of the container is folded outward by the second forming groove, and the curling portion is further incorporated by the first forming groove and the second forming groove being wound in cooperation with each other. In the method of forming
In the second molding groove of the second mold, the position in the central axial direction of the bottom surface changes in the circumferential direction, and the bottom surface protrudes from the container from the container, and the protruding region most protrudes toward the container With the most retracted area,
In the process of approaching the first mold while the second mold rotates, the protruding area of the second molding groove is first pressed against a part of the opening edge, and from the part of the opening edge It is characterized in that the folding of the opening edge to the outside is started, and the projecting region folds the opening edge over the entire circumference as it moves in the circumferential direction while pushing the opening edge.

Another aspect of the present invention is an apparatus for forming a curled portion at the opening edge of a paper container,
A receiver for holding the container, a first mold for finish curling provided in the receiver and having an annular first molding groove, and an annular precurling molding groove for the container, the container along the central axis of the container The mold has a pre-curl mold for pressing the pre-curl forming groove against the opening edge and folding the opening edge to the outside to form a folded portion, and an annular second forming groove, Finishing curl which forms the curled part by winding the folded-back part inside by cooperation of the first forming groove and the second forming groove by approaching the first mold for finish curl along the central axis. And a second mold,
The position of the central axis of the bottom surface of the forming groove for pre-curl changes along the circumferential direction, and the protruding area where the bottom surface protrudes most to the container side and the retracted area where the bottom surface is most retracted from the container It is characterized by having.

  Preferably, the pre-curl forming groove has an inclined region connecting the projecting region and the receding region, and in this inclined region, the bottom surface of the pre-curl forming groove is inclined with respect to a plane orthogonal to the central axis ing.

Preferably, the projecting regions of the forming groove for precurling are formed by the intersection of inclined regions located on both sides thereof, and the bottom of the forming groove for precurling in the projecting regions and the inclined regions on both sides thereof is orthogonal to the central axis. When viewed from the direction of
According to this configuration, since the projecting region is narrow and partial folding of the opening edge can be locally started, the initial processing load of the pre-curling process can be further reduced.

Preferably, the pre-curl forming groove, the first forming groove and the second forming groove are non-circular corresponding to the shape of the body of the container, and the projecting region of the pre-curl forming groove is for the pre-curl. The forming groove is located at the portion where the radius of curvature is the largest, and the receding area is located at the portion where the radius of curvature is the smallest.
According to the above configuration, it is possible to reliably reduce the processing load at a portion of the trunk portion where the radius of curvature is the largest and prone to buckling.

Preferably, the container is in line symmetry with respect to two reference lines perpendicular to each other, and a plurality of the projecting and receding regions of the pre-curl forming groove are respectively formed, and the forming positions of the projecting regions and the forming positions of the receding regions are the above It is symmetrical about two reference lines.
According to the above configuration, the processing load can be applied to the container with good balance, and the pre-curling process can be smoothly performed.

  Preferably, in each of the bottom surfaces of the first and second molding grooves, the position in the central axial direction of the bottom surface is constant over the entire circumference.

The present invention is applied to the curl portion forming apparatus which does not execute the pre-curl process as follows.
A receiver for holding a paper container, a first mold provided in the receiver and having an annular first molding groove, and a second mold having an annular second molding groove, the second mold An apparatus for forming a curled portion by winding the opening edge inward by the cooperation of the first forming groove and the second forming groove in the process of approaching the first mold along the central axis of the container; In the second molding groove of the second mold, the position in the central axial direction of the bottom surface changes in the circumferential direction, and the bottom surface is the most projecting region projecting to the container side, and the bottom surface is the most from the container It is characterized by having a receding retreat area.

In a rotary curl forming apparatus for a circular paper container, the invention is applied as follows.
A receiver for holding the container, a first mold provided in the receiver and having an annular first molding groove, and a second mold having an annular second molding groove; An apparatus for forming a curled portion by winding the opening edge inward by the cooperation of the first forming groove and the second forming groove in the process of approaching the first mold along the central axis of the container while rotating. In the second molding groove of the second mold, the position in the central axial direction of the bottom surface of the second molding groove changes over the circumferential direction, and the bottom surface of the second molding groove of the second mold groove in the container , And is most characterized by having a retreating area which is most retreated from.

In the above-described rotary curling unit molding apparatus, preferably, a plurality of projecting regions of the bottom surface of the second molding groove are formed at equal intervals in the circumferential direction.
According to this configuration, it is possible to form the curled part stably with good balance.

  According to the present invention, without changing the shape of the opening edge of the container before forming the curled portion, the processing load on the container in the forming step of the curled portion can be reduced, and buckling of the body of the container occurs. It can be prevented.

(A) is a perspective view showing a paper container of a final shape in which the curled portion is formed by the method and apparatus according to the first embodiment of the present invention, and (B) is made of paper of an intermediate shape before forming the curled portion. It is a perspective view of a container. It is the schematic of the curl part molding apparatus of 1st Embodiment. It is sectional drawing which shows the bending process initially performed by 1st Embodiment. It is a bottom view of the metal mold | die for bending of FIG. (A), (B) is sectional drawing which shows sequentially the pre-curl process performed in the said 1st Embodiment. It is a bottom view of the mold for precur used in the same 1st embodiment. It is a principal part enlarged view explaining the difference in the depth of the forming groove for pre curls of the above-mentioned mold for pre curls. (A) shows the state of the container opening edge in the initial stage of the pre-curling step in the projecting area of the pre-curl forming groove, and (B) shows the state of the simultaneous opening edge in the retracted area of the pre-curl forming groove. (A) shows the state of the container opening edge at the end of the pre-curling step in the projecting region of the pre-curl forming groove, and (B) shows the state of the simultaneous opening edge in the retracted region of the pre-curl forming groove. (A), (B) is sectional drawing which shows the finishing curl process implemented by said 1st Embodiment in order. It is the schematic which shows the pre-curling process in 2nd Embodiment of this invention. It is the schematic which shows the curl part formation method of 3rd Embodiment of this invention. It is a perspective view of the container produced by the curl part molding method of a 4th embodiment of the present invention. It is sectional drawing which shows the curl part formation method of 4th Embodiment.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1A shows a paper container 1 in a final shape. The container 1 has a body 2, a bottom 3, and a curled portion 4C as an opening edge. The container 1 is non-circular in plan view, and in this embodiment is elliptical, and is symmetrical about two orthogonal reference lines of a major axis and a minor axis. The curled portion 4C is larger than the bottom portion 3 and the body 2 is tapered such that it gradually spreads from the bottom portion 3 toward the curled portion 4C.

  FIG. 1B shows a container 1 'of an intermediate shape before forming the curled portion 4C. In this container 1 ′, an opening edge 4 </ b> A provided as a curling portion is continuous with the body 2 and extends upward with a taper equal to that of the body 2. In other words, the opening edge 4A extends in the extension direction of the body 2. The leading edge of the opening edge 4A is at the same height over the entire circumference. That is, the position in the central axis L (see FIG. 3) direction of the container 1 'is constant over the entire circumference.

First, the manufacturing process of the intermediate shaped container 1 ′ will be briefly described.
A cardboard is obtained by punching out a sheet in which a resin is laminated on a base paper in a fan shape. A similar sheet is punched to obtain an oval shaped bottom sheet.
The above-mentioned cardboard is wound on a mandrel and welded at its both ends to form a tapered oval cylinder. The container 1 ′ is obtained by welding and fixing the peripheral edge of the bottom sheet to the end edge of the cylinder.

The container 1 of the final shape is obtained by molding the opening edge 4A of the container 1 'of the intermediate shape by using the curl portion forming apparatus of FIG.
The curled portion forming apparatus is provided with a rotating table 10, and a plurality of, for example, eight receivers 20 (not shown in FIG. 2 and shown only in FIG. 3) are provided at equal intervals in the circumferential direction on the outer periphery of the rotating table 10. ) Are equally spaced in the circumferential direction, and each receiver 20 is provided with a first mold 30 for finishing curl separately or integrally.

  The receiver 20 and the first mold 30 stop at the loading position P1, the lubrication position P2, the bending position P3, the pre-curling position P4, the finishing curling position P5, and the unloading position P6 for a predetermined time in this order by intermittent rotation of the rotation table 10. It is supposed to be.

  The container 1 'of the intermediate shape is loaded into the receiver 20 at the loading position P1, the lubricant is applied to the opening edge 4A at the lubrication position P2, and the opening die 4A is bent by the bending die 40 at the bending position P3. The leading edge is bent outward, the opening edge 4A is folded back by the precursing die 50 at the precurling position P4, and the second die 60 for finishing curling and the first die 30 at the finishing curling position P5. The folded back portion is rolled inward to form the curled portion 4C. Finally, the container 1 of the final shape is unloaded at the unloading position P6.

The details will be described below.
As shown in FIG. 3, the receiver 20 has a support hole 21 conforming to the shape of the body 2 of the container 1 ′, and after the container 1 ′ is loaded into the support hole 21 at the loading position P1, The container 1 'is kept held until the discharge position P6. In this loaded state, the central axis L of the container 1 ′ passes through the rotation center of the turntable 10.

  The first mold 30 fixed to the receiver 20 relates to the molding of the container 1 ′ only at the finish curl position P5, and has an oval shaped accommodation hole 31 in which the body 2 of the container 1 ′ is accommodated. In order to surround this accommodation hole 31, it has an elliptical shaped annular formed groove 32 (first formed groove).

  The cross-sectional shape of the forming groove 32 is U-shaped, and the cross-sectional shape and depth are constant over the entire circumference, and the height of the bottom surface, ie, the central axis of the first mold 30 (container 1 ' The position in the direction of the central axis L) is constant over the entire circumference.

  The opening edge 4A of the container 1 'in the loaded state protrudes from the first mold 30 in the central axis L direction. The protrusion amount of the opening edge 4A is constant over the entire circumference.

  As shown in FIG. 3, the bending mold 40 faces the container 1 ′ at the bending position P <b> 3 on the central axis L. As shown in FIGS. 3 and 4, the mold 40 has a disk-shaped holder 41 and a large number of heads 42 fixed to the holder 41 and spaced in the circumferential direction. Each head 42 has a downwardly projecting forming portion 42a, and is arranged to advance while curving radially outward. All the heads 42 are arranged to draw a spiral when viewed from the central axis L direction.

  The mold 40 is brought close to the container 1 'and rotated along a central axis L by a drive unit 49 schematically shown in FIG. Then, the formed portion 42a of the head 42 abuts on the leading edge 4a of the opening edge 4A of the container 1 ', and the leading edge 4a is slightly bent radially outward. This bending is to facilitate the folding of the opening edge 4 in the pre-curling process described later.

  Next, the precursing die 50 and the precurling process will be described with reference to FIGS. 5 to 9. As shown in FIG. 5A, the pre-curl mold 50 faces the container 1 'at the pre-curl position P4 on the central axis L, and surrounds the insertion convex portion 51 and the root of the insertion convex portion 51. An annular formed groove 52 (pre-curled forming groove) is provided. The insertion convex portion 51 has an elliptical cross section, and its outer surface is tapered.

  The forming groove 52 has an oval shape corresponding to the opening edge 4A of the container 1 ', and its cross-sectional shape is U-shaped. The cross-sectional shape and depth of the forming groove 52 change in the circumferential direction, and the height of the bottom surface, that is, the position in the central axis L direction changes in the circumferential direction. The details will be described below.

  The forming groove 52 is shallowest at two points located on the elliptical short axis A1 shown in FIG. 6, and its bottom surface most protrudes toward the container 1 '. Hereinafter, these two points are referred to as a projecting area 52x. The forming groove 52 is the deepest in a region centered on two points located on the major axis A2 of the above-mentioned ellipse, and the bottom surface thereof is most retracted from the container 1 '. Hereinafter, this portion is referred to as a receding area 52y. In order to facilitate understanding, in FIG. 7, the difference between the position in the central axis L direction of the bottom surface of the protruding area 52 x and the bottom surface of the receding area 52 y is denoted by a symbol H.

  In the receding area 52y, the forming groove 52 has a constant depth over a predetermined length (over a predetermined angle range) in the circumferential direction, and the bottom surface has a constant position in the central axis L direction of the container 1 '. .

  The forming groove 52 has an inclined area 52z connecting the projecting area 52x and the receding area 52y. In this inclined area 52z, the forming groove 52 is deepened toward the retreat area 52y, and the bottom surface is inclined so as to gradually retreat (inclined with respect to a plane orthogonal to the central axis L). In the present embodiment, the projecting area 52x is locally formed at the point where the adjacent paired inclined areas 52z intersect. As a result, as shown by the broken line in FIG. 5, the bottom of the inclined area 52z paired with the projecting area 52x has a chevron when viewed from the direction orthogonal to the central axis L of the container 1 '.

As is apparent from the above description, the projecting region 52x of the forming groove 52 is located at a portion where the radius of curvature in the elliptical shape is the largest, and the center of the receding region 52y is located at a portion where the radius of curvature is the smallest.
The ellipse of the forming groove 52 is symmetrical about the short axis A1 and the long axis A2 (two reference lines), and the forming positions of the two projecting areas 52x, the two receding areas 52y, and the four inclined areas 52 are also respectively The line symmetry is made with respect to the minor axis A1 and the major axis A2.

  As shown in FIG. 5A, when the mold 50 is brought close to the mold 30 and the container 1 'along the central axis L by the drive unit 59 (shown schematically in FIG. 2), the insertion convex portion thereof 51 enters the container 1 ', and as a result, as shown in FIG. 5 (B), the forming groove 52 contacts the opening edge 4A of the container 1' and the opening edge 4A is folded outward to form the folded portion 4B.

  In the pre-curling step (folded portion forming step), as shown in FIG. 8A, the projecting region 52x of the pre-curl forming groove 52 first strikes a part of the opening edge 4A, and the opening edge 4A is The above-described folding is started from a part. At this time, as shown in FIG. 8 (B), in the receding area 52y of the pre-curl forming groove 52, the return forming of the opening edge portion 4A has not started.

  Thereafter, the folding start position of the opening edge 4A is shifted to the sloped area 52z on both sides of the projecting area 52x, and further shifted to the receding area 52y. As described above, since the folding is not simultaneously started over the entire circumference of the opening edge 4A and the folding start position moves along the circumferential direction, the processing load may be small, and the occurrence of buckling in the trunk 2 is prevented. can do.

  In particular, in the present embodiment, since the bending is locally started from two points where the curvature radius is maximum and the buckling of the body 2 is most likely to occur, the buckling of the body 2 can be reliably prevented. Finally, in the area where the radius of curvature is small at the opening edge 4A, the folding and forming is started substantially simultaneously by the receding area 52y of the pre-curl forming groove 52, but the radius of curvature is small in the barrel 2 corresponding to this area. Because the strength against is relatively high, no buckling occurs.

  In the pre-curling step, since the projecting area 52x, the receding area 52y, and the inclined area 52z are symmetrical with respect to the minor axis A1 and the major axis A2, it is possible to perform balanced folding and stable folding.

  The above-mentioned forming groove 52 can be suitably designed and changed according to container 1 '. For example, when the strength of the container 1 ′ is low, the receding area 52 y may be narrowed (for example, made approximately to a dot) in the same manner as the protruding area 52 x to form the inclined area 52 z over the entire circumference. Further, the projecting area 52x may occupy not a point but a predetermined angular range. However, it is preferable that the range occupied by the protruding region 52x be narrower than the range occupied by the receding region 52y.

  At the end of the pre-curling step, as shown in FIGS. 9A and 9B, in the folded portion 4B, the folding amount Ly of the portion 4By formed in the receding area 52y is the protruding area 52x of the forming groove 52. It is smaller than the folding amount Lx of the molded portion 4Bx. Therefore, in the folded back portion 4B, the height Hy (for example, the height from the first mold 30) of the portion 4By formed in the receding region 52y is the height of the portion 4Bx formed in the protruding region 52x of the forming groove 52. It is higher than Hx.

  Next, the second mold 60 for finish curling and the finish curling process will be described in detail with reference to FIG. As shown in FIG. 10A, the second mold 60 is opposed to the first mold 30 and the container 1 ′ at the finish curl position P5 on the central axis L of the first mold 30 and the container 1 ′. An annular formed groove 62 (second formed groove) surrounding the root of the insertion convex portion 61 is provided. The insertion convex portion 61 has an elliptical cross section, and its outer surface is tapered.

  The forming groove 62 has an oval shape corresponding to the opening edge 4 of the container 1 'and has a U-shaped cross section. The depth of the forming groove 62 is constant, and the position of the bottom surface in the central axis L direction is constant over the entire circumference.

  As shown in FIG. 10A, when the second mold 60 is brought close to the first mold 30 and the container 1 ′ along the central axis L by the drive unit 69 (shown schematically in FIG. 2), The insertion convex portion 61 enters the container 1 ′, and eventually, as shown in FIG. 10 (B), the second molding groove 62 contacts the folded portion 4B of the container 1 ′ and further deepens this fold back to the first mold 30. Then, the first molding groove 32 and the second molding groove 62 cooperate with each other to wind the folded portion 4B inward, thereby molding the curled portion 4C, and the container 1 of the final shape is completed.

  As described above, in the folded back portion 4B, the height Hy of the portion 4By formed in the receding region 52y is higher than the height Hx of the portion 4Bx formed in the protruding region 52x of the forming groove 52, and corresponds to the inclined region 52z. At the site 4Bz, the temperature gradually decreases toward the site 4Bx (see FIG. 10A). Therefore, in the finishing curling process, the second molding groove 62 first strikes the portion 4By, and then hits the portion 4Bz and the portion 4Bx in order. As described above, since the forming is not simultaneously started over the entire circumference of the folded back portion 4B, it is possible to prevent the buckling of the body 2 also in this finish curling step.

  As described above, the curled portion 4C is formed, but as described above, the height of the intermediate-shaped container 1 ′ and the opening edge 4A is constant, and the depths of the forming grooves 32 and 62 are constant (forming groove Since the position in the central axial direction of the bottom surfaces 32 and 62 is constant), the curled portion 4C can have the same amount of winding and uniform thickness over the entire circumference.

  When the curled portion 4C was formed using the curled portion forming apparatus of the present embodiment, only two of the 10000 containers produced buckling of the body portion 2 (buckling occurrence rate 0.2%). As a comparative example, when the curled portion 4C is formed using a curled portion forming apparatus in which the forming groove 52 has a constant depth over the entire circumference and the height of the bottom surface is constant, 10000 out of 10000 containers The buckling of part 2 occurred (buckling incidence rate 100%).

Next, another embodiment of the present invention will be described.
In the second embodiment shown in FIG. 11, the pre-curling step is performed on the intermediate-shaped container 1 ′ shown in FIG. 1 (B), omitting the bending step. As described above, in the pre-curling process, since the start of folding is not simultaneously performed over the entire circumference, the processing load can be reduced because the start position of the folding is moved in the circumferential direction. Therefore, pre-curling can be performed while avoiding buckling even if the bending process is omitted. The productivity can be improved by omitting the bending and forming. Others are the same as in the first embodiment, and therefore detailed description will be omitted.

  In the third embodiment shown in FIG. 12, the curled portion is formed on the opening edge 4A of the container 1 'of the intermediate shape shown in FIG. 1 (B) without performing bending and pre-curling. The molding groove 32 'of the first mold 30' used in this embodiment has the same cross-sectional shape as the molding groove 32 of the first mold 30 of the first embodiment. The molding groove 62 'of the second mold 60' is similar in cross-sectional shape to the molding groove 62 of the second mold 60 of the first embodiment, but it protrudes in the same manner as the molding groove 52 for pre-curling of the first embodiment. It has an area, a receding area and a sloped area. As the second mold 60 'approaches the first mold 30' along the central axis, the forming groove 62 'folds the opening edge 4A outward, and the forming grooves 32', 62 'cooperate with each other. The curled portion is formed by winding the folded portion inward. The operation in the projecting area, the inclined area, and the receding area of the forming groove 62 'is the same as that of the forming groove 52 for pre-curling in the first embodiment, and thus the detailed description will be omitted.

The first to third embodiments can be applied not only to an elliptical container but also to forming a curled portion of a polygonal container or an oval container. In the case where the opening edge of the container has a straight portion (the radius of curvature is infinite), in the formed groove, it is preferable to make the protruding region in the center of the straight portion corresponding to the straight portion of the opening edge.
The first to third embodiments can also be applied to a circular container. In this case, it is preferable that the projecting regions of the forming groove be formed at a plurality of places equally spaced in the circumferential direction, and the receding regions be formed at the center between the projecting regions.

  FIG. 13 shows a circular container 5. The container 5 has a body 6, a bottom, and a curled portion 7C as an opening edge. FIG. 14 shows a molding method and apparatus for molding the curled portion 7C of the circular container 5 (fourth embodiment of the present invention).

  In the fourth embodiment, the first molding groove 72 of the first mold 70 has an annular shape. The second mold 80 not only moves toward the first mold 70 in the central axis L direction, but also rotates in the process of this movement. The second molding groove 82 of the second mold 80 has an annular shape, and has a projecting area 82x, a receding area 82y, and an inclined area 82z. The projecting regions 82x are formed at a plurality of points at equal intervals in the circumferential direction (for example, formed at two points spaced by 180 °), and the receding regions 82y are formed at the center between the projecting regions 82x over a predetermined angle range The protruding area 82x and the receding area 82y are connected via the sloped area 82z.

The receiver 20 is loaded with an intermediate shaped container 5 '. The container 5 'has an opening edge 7A extending upward to the body 6 continuously. The opening edge 7A has a constant height over the entire circumference.
The opening edge 7A is folded outward by bringing the second mold 80 close to the first mold 70 along the central axis L while rotating the second mold 80, and the folded portion is further divided into the first forming groove 72 and the second forming groove 72. By cooperation of the forming groove 82, the opening edge 7A is rolled inward to form the curled portion 7C.
The second molding groove 82 of the second mold 80 does not simultaneously contact the opening edge 7A over the entire circumference, and the projection area 82x of the second molding groove 82 first strikes a part of the opening edge 7A. An outward turning from a part of the opening edge 7A is started. As the projecting area 82x moves in the circumferential direction while pushing the opening edge 7A, the opening edge 7A is folded over the entire circumference.
As described above, by rotating the second mold 80, the curled portion 7C can be made to have the same winding amount and uniform size over the entire circumference. Moreover, the container 5 of the same height is obtained over the entire circumference.

  The present invention is not limited to the above embodiment, and various modifications can be adopted without departing from the scope of the invention. For example, the transfer of the precursing mold to the container and the transfer of the second mold to the first mold are relative, and the container is moved toward the precursing mold contrary to the above embodiment. Alternatively, the first mold may be moved toward the second mold. In the fourth embodiment, the first mold may be rotated instead of rotating the second mold.

  The present invention is applicable to the manufacture of a container with a curled portion.

DESCRIPTION OF SYMBOLS 1 container 1 'of final shape intermediate container 2 barrel 3 bottom 4A opening edge 4B of intermediate container 4B folded back portion 4C curled portion 20 receiver 30 first mold for finishing curl 30' first mold 32, 32 'First molding groove 50 mold for pre-curling 52 molding groove for pre-curl 52 x projecting area 52 y receding area 52 z inclined area 60 second mold for finishing curl 60' second mold 62, 62 'second molding groove 70 first gold Mold 72 First molding groove 80 Second mold 82 Second molding groove 82x Protrusion area 82y Retraction area 82z Inclination area

Claims (12)

A method of forming a curled portion on the opening edge of a paper container,
The pre-curl molding groove is pressed against the opening edge by bringing the pre-curl mold having an annular pre-curl molding groove close to the container along the central axis of the container, and the opening edge is folded outward. Pre-curl process for forming the folded portion
By bringing the second mold for finish curl having the annular second molding groove closer to the first mold for finish curl disposed on the container side and having the first molding groove having an annular shape, along the central axis, The first forming groove and the second forming groove cooperate with each other to wind the folded-back portion inward and form a curling portion;
The position of the central axis of the bottom surface of the forming groove for pre-curl changes along the circumferential direction, and the bottom surface of the pre-curl molding groove is the most projecting toward the container, and the bottom surface is the most retracted from the container. And an inclined area connecting the projecting area and the receding area, in which the bottom surface of the precurl forming groove is inclined with respect to a plane orthogonal to the central axis,
In the pre-curling step, the projecting area of the pre-curl forming groove is first pressed against a part of the opening edge, the folding is started from the part of the opening edge, and the folding start position at the opening edge A method for forming a curled portion of a paper container , comprising: moving from the projecting area through the inclined area to the receding area . Each of the first molding groove and the bottom surface of the second molding groove has a constant position in the central axial direction of the container over the entire circumference,
The method for forming a curled portion of a paper container according to claim 1 , wherein, in the finish curling step, the second forming groove is first pressed against a portion formed by the receding area in the folded portion. . The second mold having an annular second molding groove is brought close to the first mold having an annular first molding groove disposed on the paper container side along the central axis of the container, thereby The second molding groove is pressed against the opening edge of the container and folded back, and the folded portion is further wound inward by the cooperation of the first molding groove and the second molding groove, whereby the curled portion is molded. In the method
In the second molding groove of the second mold, the position in the central axial direction of the bottom surface changes in the circumferential direction, and the bottom surface is the projecting region most projecting toward the container, and the bottom surface is the container And the inclined area connecting the projecting area and the retreating area, and in this inclined area, the bottom surface of the second forming groove is inclined with respect to the plane orthogonal to the central axis. ,
In the course of the second mold closer to the first mold, first pressing the protruding area of the second molding groove on the part of the opening edge portion, the opening edge from a portion of the opening edge A method of forming a curled portion of a paper container, characterized in that folding to the outside of the part is started, and the folding start position at the opening edge moves from the projecting area to the receding area via the inclined area . The second mold having an annular second molding groove is disposed on the side of a circular paper container and the second mold having an annular second molding groove is rotated to the central axis of the container while being rotated. By bringing them close together, the opening edge of the container is folded outward by the second forming groove, and further, the folding portion is wound inward by the first forming groove and the second forming groove in cooperation with each other. In the method of forming the curled portion ,
In the second molding groove of the second mold, the position in the central axial direction of the bottom surface changes in the circumferential direction, and the bottom surface protrudes from the container from the container, and the protruding region most protrudes toward the container With the most retracted area,
In the process of approaching the first mold while the second mold rotates, the protruding area of the second molding groove is first pressed against a part of the opening edge, and from the part of the opening edge A paper container characterized in that folding of the opening edge to the outside is started, and the projecting region folds the opening edge over the entire circumference as it moves in the circumferential direction while pushing the opening edge. Curled part molding method. An apparatus for forming a curled portion at the opening edge of a paper container,
A receiver for holding the above container,
A first mold for finish curl having an annular first molding groove provided in the receiver;
An annular pre-curl forming groove is provided, and the pre-curl forming groove is pressed against the opening edge by approaching the container along the central axis of the container, and the opening edge is folded outward and turned around Mold for pre-curl, and
An annular second forming groove is provided, and by approaching the first mold for finish curl along the central axis, the folded portion is inside by cooperation of the first forming groove and the second forming groove. A second mold for finish curling which is rolled up into the above to form the curled portion;
Equipped with
The position of the central axis of the bottom surface of the forming groove for pre-curl changes along the circumferential direction, and the protruding area where the bottom surface protrudes most to the container side and the retracted area where the bottom surface is most retracted from the container And a sloped area connecting the projecting area and the receding area, wherein the bottom surface of the pre-curl forming groove is inclined with respect to a plane orthogonal to the central axis in the inclined area. Curl part molding device for container made. The projecting regions of the pre-curl forming groove are formed by the intersections of inclined regions located on both sides, and the bottom of the pre-curl forming groove in these projecting regions and the inclined regions on both sides is from the direction orthogonal to the central axis The apparatus for forming a curled portion of a paper container according to claim 5 , characterized in that it has a chevron shape when viewed. The pre-curl forming groove, the first forming groove and the second forming groove are non-circular corresponding to the shape of the body of the container, and the projecting region of the pre-curl forming groove is the pre-curl forming groove 7. The apparatus for forming a curled portion of a paper container according to claim 6 , wherein the curled area is located at the largest area and the receding area is located at the smallest area. The vessel is symmetrical about two orthogonal reference lines,
The projection area and the receding area of the pre-curl forming groove are respectively formed in a plurality, and the formation position of the projecting area and the formation position of the receding area are symmetrical with respect to the two reference lines. The curl part shaping | molding apparatus of the paper containers in any one of 5-7 . The paper according to any one of claims 5 to 8 , wherein each of the first molding groove and the bottom surface of the second molding groove has a constant position in the central axial direction of the bottom surface over the entire circumference. Curl part molding device for container made. A receiver for holding a paper container, a first mold provided in the receiver and having an annular first molding groove, and a second mold having an annular second molding groove;
In the process in which the second mold approaches the first mold along the central axis of the container, the opening edge is rolled inward by the cooperation of the first forming groove and the second forming groove, and the curled portion is formed. In the forming apparatus,
In the second molding groove of the second mold, the position in the central axial direction of the bottom surface changes in the circumferential direction, and the bottom surface is the most projecting region projecting to the container side, and the bottom surface is the most from the container There is a receding receding area, and a sloped area connecting the projecting area and the receding area, and in this sloped area, the bottom surface of the second formed groove is inclined with respect to a plane orthogonal to the central axis. A curling unit for a paper container, characterized in that A receiver for holding a circular paper container, a first mold having an annular first molding groove provided in the receiver, and a second mold having an annular second molding groove;
In the process of approaching the first mold along the central axis of the container while rotating the second mold, the opening edge is rolled inward by the cooperation of the first forming groove and the second forming groove. In an apparatus for forming a curled portion,
In the second molding groove of the second mold, the position in the central axial direction of the bottom surface changes in the circumferential direction, and the bottom surface is the most projecting region projecting to the container side, and the bottom surface is the most from the container An apparatus for forming a curled portion of a paper container, characterized by having a retreated retreated area. The apparatus for forming a curled portion of a paper container according to claim 11 , wherein a plurality of projecting regions of the bottom surface of the second molding groove are formed at equal intervals in the circumferential direction.

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