JP4206499B2 - Tapered container mold - Google Patents

Description

  The present invention relates to a molding die for a tapered container.

When manufacturing a taper container by deep drawing from a metal material such as an aluminum foil, there is a problem that wrinkles are generated on the side wall of the container. An apparatus for manufacturing a tapered container which attempts to solve this problem is already known as shown in the following patent document. In this apparatus, the mold used in the bottomed tapered cylindrical body process is a die having a taper on the inner peripheral surface and a punch having a taper on the outer peripheral surface, both having a taper angle of 1.5 °. If such a mold is used to deeply draw a circular blank or a previously formed bottomed straight cylindrical body to form a bottomed tapered cylindrical body, wrinkles are generated on the side wall of the container. Then, the problem of wrinkle generation is avoided by arranging a mold having a stepped portion in the middle of the height of the bottomed straight cylindrical body in the preceding process.
Japanese Patent Laid-Open No. 1-150418

  The conventional tapered container manufacturing apparatus for preventing the generation of wrinkles on the container side wall is inevitably a complicated mechanism.

  It is an object of the present invention to provide a tapered mold for forming a tapered container in which only a tapered mold is used and no wrinkles are formed on the side wall of the container and the molding material is not broken.

  A molding die for a tapered container according to the invention of claim 1 is a tapered cup shape having a flange formed by deep drawing a laminated sheet comprising an aluminum foil core layer and a synthetic resin coating layer formed on both sides thereof. A mold used for forming a container, wherein a finish roughness Ra of a punch Rp portion is 0.3 to 3 μm, and a taper angle of a punch is 0.01 to a taper angle of a die. It is made 0.5 ° smaller.

  According to a second aspect of the present invention, in the molding die for the tapered container according to the first aspect, the radius of curvature of the Rp portion of the punch is 0.5 to 15 mm.

  According to a third aspect of the present invention, in the molding die for a tapered container according to the first or second aspect, the deep drawing is multistage deep drawing, and the die is used in the final stage.

As a processing finishing method of the Rp portion of the punch, there is a method of polishing with a file or sandblast. In general, it is considered that it is advantageous in terms of molding that a molding material contact portion of a mold has a friction coefficient as small as possible so that the molding material can easily move on the mold. However, if the roughness of the Rp portion of the punch is increased to some extent, the tensile force applied to the molding material at the tip of the punch can be reduced, and the molding material is less likely to break. In the invention of claim 1, the processing finish roughness Ra of the Rp portion of the punch is limited to 0.3 to 3 μm because the effect of roughening the surface is not recognized when the processing finish roughness Ra is less than 0.3 μm. This is because the molding material may be broken, and when the processing finish roughness Ra exceeds 3 μm, the molding material is broken by the unevenness of the Rp portion of the punch at the start of molding. Within the above range, a more preferable finishing roughness Ra is 0.5 to 2 μm. At the same time, the taper angle of the punch is limited to be 0.01 to 0.5 ° smaller than the taper angle of the die because the molding material thickness in the vicinity of the die Rd and the punch Rp in the container side wall is limited. This is to prevent generation of wrinkles on the side wall of the container due to the difference. In general, in the case of drawing, the thickness of the side wall of the container varies in the height direction and becomes thinner as it approaches the bottom. However, when the side wall is tapered, the shrinkage in the circumferential direction of the molding material is greater as it is closer to the bottom, so that the material is easily folded during molding and wrinkles are likely to occur. The generation of wrinkles occurs when the material that shrinks in the circumferential direction in the space between the punch and the die closely contacts the peripheral surface of the punch and the die at the end of molding. Therefore, the gap between the punch and the die may be narrowed so that the shrinking material will not be folded at the end, but if this gap is too narrow, the material may break. However, since the material hardly shrinks in the vicinity of the opening, it is not necessary to narrow the gap. After all, it is preferable that the taper angle of the punch is reduced by 0.01 to 0.5 ° with respect to the taper angle of the die. When the punch taper angle to be reduced with respect to the die taper angle is less than 0.01 °, the effect of preventing wrinkles is reduced, and the punch taper angle to be reduced with respect to the die taper angle is 0.5 °. If it exceeds, wrinkles occur in the vicinity of Rd of the die on the side wall of the container. The molding material is fixed at the tip of the punch at the time of molding, and the molding force is thinned at the Rp portion of the punch because the tensile force works while the majority of the drawing load is supported at the Rp portion of the punch. . In the invention of claim 2, the radius of curvature of the Rp portion of the punch is limited to 0.5 to 15 mm because the thickness of the molding material at this portion is less than 0.5 mm when the radius of curvature of the Rp portion of the punch is less than 0.5 mm. This is because when the radius of curvature at the Rp portion of the punch exceeds 15 mm, the molding material does not conform to the tip of the punch and a predetermined sharp shape may not be obtained. In the case of forming a tapered cup-shaped container using the mold according to the first aspect of the invention, it is possible to perform molding once when the ratio of the depth to the inner diameter of the mouth of the container is within 70%, but 70% In the case of exceeding the above, a single-stage or multi-stage bottomed straight cylindrical body forming step is required before that.
In a tapered cup-shaped container having a flange formed by deep drawing a laminated sheet composed of an aluminum foil core layer and a synthetic resin coating layer formed on both sides thereof, the thickness of the aluminum foil core layer is 60 ˜200 μ is preferable, and more preferable thickness is 100 to 140 μ. If the same thickness is less than 60 μm, the material may be broken during the deep drawing of the container, or the flange may be uneven. If the same thickness exceeds 200 μm, it is uneconomical because only the amount of aluminum used is increased. . The thickness of the synthetic resin coating layer formed on both surfaces of the aluminum foil core layer is 1 to 300 μm, respectively. If the thickness is less than 1 μm, the material may break during deep drawing of the container. If the thickness exceeds 300 μm, cold deep drawing becomes difficult and the productivity of the container deteriorates. As a method of forming the synthetic resin coating layer on both surfaces of the aluminum foil core layer, there are a method of bonding a synthetic resin film to the aluminum foil and a method of coating the synthetic resin on the aluminum foil. The thickness in the former case is 10 ˜300 μ is preferable, more preferably 50 to 250 μ, and the thickness in the latter case is preferably 1 to 10 μ, and more preferably 3 to 8 μ. The ratio of the thickness of the aluminum foil core layer to the total thickness of the laminated sheet is preferably 25 to 80%. If the ratio is less than 25%, the moldability is poor and the material may be broken, and if the ratio exceeds 80%, wrinkles that are folded and overlapped on the side surface of the container are likely to occur. Specific examples of the synthetic resin used on the outer surface side of the container include polyethylene, polypropylene, polyester and copolymers thereof in the case of a film, and thermosetting acrylic resin and epoxy resin in the case of coating. . In addition, since the synthetic resin used on the inner surface side of the container is required to have a heat sealing property in the flange portion, specific examples thereof include polyethylene, polypropylene, polyester and copolymers thereof in the case of a film, In the case of coating, vinyl chloride acetate and acid-modified polyolefin are exemplified. This container is mainly sold by filling and sealing beverages such as coffee, tea, and soup, and the purchaser peels off the heat-sealed lid from the container flange and drinks the contents. The inner diameter of the part is preferably 50 to 100 mm, the same depth is 50 to 150 mm, and the ratio of the depth to the inner diameter of the mouth part is preferably 1: 1 or more. Outside these ranges, it is unsuitable as a container for the above applications. The width of the flange is preferably 3 to 10 mm in view of the necessary width for heat sealing including the curled edge, storage space, and ease of drinking. The taper angle of the tapered cup-shaped container is preferably 1 to 5 °. When the taper angle is less than 1 °, when the containers are transported, the containers are too close to each other and difficult to remove, and when the taper angle exceeds 5 °, the peripheral surface of the container is wrinkled.

    The tapered cup-shaped container is manufactured as follows. That is, when forming a tapered cup-shaped container equipped with a flange by deep drawing a laminated sheet composed of an aluminum foil core layer and a synthetic resin coating layer formed on both surfaces thereof, the deep drawing process is A multi-stage process comprising a bottomed straight cylinder forming process for forming a blank into a bottomed straight cylinder and a bottomed tapered cylinder forming process for forming the bottomed straight cylinder following this process into a bottomed cylindrical cylinder. It is a process. The bottomed straight cylindrical body forming step includes a first step of forming a blank into a bottomed straight cylindrical shape, and a first step of further deep drawing the bottomed straight cylindrical body obtained in the first step. Alternatively, it consists of a plurality of steps. In the step of forming a cylindrical body with a bottomed taper, the taper angle applied to the cylindrical body is preferably 1 to 5 °, and the drawing ratio is preferably 80% or more. If the drawing ratio in the bottomed tapered cylindrical body forming step is less than 80%, the side wall of the container may be broken. From the viewpoint of productivity, 80 to 90% is more preferable.

  According to the molding die for a tapered container of the present invention, there is no breakage of the molding material at the time of molding even in deep drawing, and wrinkles are not generated on the side wall of the container.

  In order to specifically explain how the present invention is carried out, examples are given below.

  An aluminum foil tapered sealing container having a flange with a curled edge is already known as disclosed in Japanese Utility Model Publication No. 6-047773. This container is suitable for packaging desserts and cooked foods, but suitable for packaging beverages such as coffee, tea, and soup, because the depth ratio to the inner diameter of the mouth is less than 1: 1. Not. However, as a beverage packaging container having the above ratio of 1: 1 or more, a synthetic resin container has been conventionally known. Synthetic resin containers, however, are inferior in gas barrier properties and light-shielding properties, so that it is difficult to stably maintain them for a long period of time in beverages that have a taste, aroma and color, such as coffee and tea. In addition, in the case of contents whose taste changes at the time of distribution, not only has it had to rely on refrigerated distribution, but it is also inferior in heat resistance, so in the case of contents that require heating at the time of eating and drinking, it is installed at a convenience store There is a drawback that it is not possible to heat the container as it is with a heater. If the aluminum container without these problems is a bottomed straight cylinder like the body of an aluminum can, the ratio of the depth to the mouth inner diameter can be made 1: 1 or more by ironing. If it is a bottom straight cylinder, there is a problem in that it cannot be transported by fitting a plurality of pieces, and occupies a lot of space.

  The tapered cup-shaped container formed using the mold according to the present invention, when sealed, can be stored for a long period of time and can be distributed at room temperature, and can be heated as it is and when many are transported. A container for sealing beverages, foods, etc. that can be fitted together and not bulky is shown in FIGS.

This container A has a flange 2 having a curl edge 1 having a width of 2.2 mm and a flange 2 having a width of 6.2 mm (including the curl edge width) and a step 3 having a substantially L-shaped vertical section at the mouth. An unstretched polypropylene coating layer 5 made of a 120 μm thick aluminum foil core layer 4 and a 200 μm thick film formed on its inner surface and a 30 μm thick film formed on its outer surface. And the ratio of the thickness of the aluminum foil core layer 4 to the total thickness is 34.3%. The inner diameter D1 is 63 mm, the bottom inner diameter D2 is 52 mm, the depth H is 100 mm, the ratio of the depth H to the mouth inner diameter D1 is 1: 1.58, and the taper angle θ of the container A is 3 °. It is said. The upper surface of the flange 2 is a smooth surface, and a lid B made of an aluminum foil 9 having a heat sealant layer 8 made of a sealant on the lower surface fills the container A with the contents, and then heat-melts the upper surface of the flange 2. FIGS. 2 and 3 show the heat-sealed state. Since the stepped portion 3 having a substantially L-shaped vertical section is present at the mouth of the tapered cup-shaped container A, the inner container does not penetrate deeply into the outer container when transporting a plurality of sealing containers together. Although it becomes easy to take out, this step part 3 does not need to be provided.

  In the cold multistage deep drawing, the first step of forming a circular blank into a bottomed straight cylinder (FIG. 4) and the first bottomed straight cylinder A1 obtained in the first step are further added. A bottomed straight cylindrical body forming step including a second step (FIG. 5) for deep drawing, narrowing the mouth and increasing the depth to obtain the second bottomed straight cylindrical body A2, and after this step The second bottomed straight cylindrical body A2 is formed into a bottomed tapered cylindrical body to obtain a bottomed tapered cylindrical body A3 having a taper angle of 3 ° (see FIG. 6). ), And the drawing ratio is 85%. Molding in each stage is performed by a separate press, and a multi-cavity mold is used in the first stage process in terms of material yield. The first bottomed straight cylindrical body A1 having a shallow depth obtained in the first stage process is conveyed to the press machine in the next second stage process. The deep second bottomed straight cylindrical body A2 obtained in the second stage process is conveyed to the press machine in the next third stage process. The curled edge 1 of the flange 2 is formed after multistage deep drawing.

  In the first stage of the bottomed straight cylindrical body molding step, a molding die 10 as shown in FIG. 7 is used. In FIG. 7, 11 is a die having a straight inner peripheral surface, 12 is a punch having a straight outer peripheral surface, 13 is a punch base, and 14 is a blank holder. Although the second step is not shown in the figure, the dimensions of the molding die 10 shown in FIG. 7 are merely changed so that the second bottomed straight cylindrical body A2 is obtained. . In the bottomed tapered cylindrical body forming step, a molding die 15 according to the present invention as shown in FIG. 8 is used. In FIG. 8, 16 is a die having a taper on the inner peripheral surface, 17 is a punch having a taper on the outer peripheral surface, 18 is a punch base, and 19 is a blank holder.

In the molding die 15, the finishing roughness Ra of the Rp portion of the punch 17 is 1 μ, the taper angle θ1 of the die 16 is 3.0 °, and the taper angle θ2 of the punch 17 is 2.8. It is ° and it is made 0.2 ° smaller. Further, the radius of curvature of the Rp portion of the punch is 3 mm. Table 1 below shows examples of the present invention and comparative examples, and shows the observation evaluation results of the molded state of the container side wall.

FIG. 2 is a half-cross sectional view of a tapered cup-shaped container formed using a mold according to the present invention. It is a perspective view of the container of FIG. 1 which shows the state sealed by the lid | cover made from aluminum foil which has a heat sealing material layer on the lower surface. FIG. 3 is a partial enlarged cross-sectional view taken along line III-III in FIG. 2. It is a front view of the 1st bottomed straight cylindrical body obtained at the process of the 1st step of multistage deep drawing. It is a front view of the 2nd bottomed straight cylindrical body obtained at the process of the 2nd step. It is a front view of the cylinder with a bottomed taper obtained at the process of the 3rd step. It is a front view of the shaping die used at the process of the 1st step. It is a front view of the shaping die used at the process of the 3rd step. It is an expanded partial sectional view of the molding die in the middle of molding in the process of the 3rd step.

Explanation of symbols

2 Flange 4 Aluminum foil core layer 5, 6 Unstretched polypropylene coating layer (synthetic resin coating layer)
7 Laminated sheet A Container 15 Mold
Ra Pp Rp finish roughness θ1 Die taper angle θ2 Punch taper angle

Claims (3)

  A die used to form a tapered cup-shaped container having a flange by deep-drawing a laminated sheet comprising an aluminum foil core layer and a synthetic resin coating layer formed on both sides thereof, and comprising a punch The Rp part has a finishing roughness Ra of 0.3 to 3 μm, and the taper angle of the punch is 0.01 to 0.5 ° smaller than the taper angle of the die. .   The mold for molding a tapered container according to claim 1, wherein the radius of curvature of the Rp portion of the punch is 0.5 to 15 mm. 3. The die for forming a tapered container according to claim 1, wherein the deep drawing is multi-stage deep drawing, and the die is used in the final stage.

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