JPH04344841A - Manufacture of di can for non-soda drinks - Google Patents

Abstract

PURPOSE:To obtain this can whose inside being filled with the hot non-soda drinks can surely become sufficient positive pressure. CONSTITUTION:In the optional cross sectional shape passing through the center axis of the DI can manufactured from a plate material, the DI can has such a bottom shape that a can bottom leg part 2 formed as projection shape from a can side wall 1 is smoothly connected the to outside of the can and a can bottom counter part 3 is formed as projection shape to the inside of the can connected from it and a can bottom dome part 4 is formed as projection shape to the outside of the can connected from it and further, after the hot non-soda drinks is filled into the DI can and sealed hermetically by fitting a cover, the can bottom dome part 4 formed as the projection shape to the outside of the can is depressed from the outside of the can with a punch 5 having axial symmetrical protruded curving face shape at a head part 51 in the condition of holding the pressure in the can to higher than the pressure at the outside of the can to deform this place to the projection shape into the inside of the can.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a DI can body for non-carbonated beverages such as fruit juice and coffee, and more specifically,
The present invention relates to a method for manufacturing DI cans for non-carbonated beverages, in which a non-carbonated beverage is hot-filled into an I-can body, and after being sealed, the can body is cooled to room temperature.

0002

BACKGROUND OF THE INVENTION Beverages that are filled into cans include carbonated drinks such as beer and cola, and non-carbonated drinks such as fruit juice and coffee. Since the former contains carbon dioxide gas, positive pressure inside the can does not cause dents on the can side wall, and DI cans (made of aluminum or steel) with thin can side walls are used as containers, which are characterized by lightweight cans. On the other hand, the latter does not contain carbon dioxide gas,
Since the can is filled hot (approximately 90° C.), the pressure inside the can is lower than that outside the can at room temperature, that is, the pressure is negative. For this reason, three-piece steel cans with high rigidity side walls are used as containers.

[0003] There are two types of containers mentioned above (two-piece D
There are two types of cans: I cans and three-piece steel cans), but DI cans are manufactured from a sheet by drawing and ironing (DI) processing. Also,
Three-piece cans are manufactured by welding or gluing plates together. These have different can side wall thicknesses due to differences in processing methods, etc., and DI
0.11-0.13 mm for cans, 0.2 for 3-piece cans
Although there is a large difference in can weight, the DI processing method is advantageous from a cost standpoint.

0004

[Problems to be Solved by the Invention] In recent years, due to advances in nitrogen filling technology, DI cans have begun to be used as containers for non-carbonated beverages as well. With this technology, the internal pressure of the can is always maintained at a pressure higher than atmospheric pressure by nitrogen filling, and it is possible to prevent the side wall of the can from becoming dented. This method is mainly used for sports drink cans, but has recently been put into practical use for other contents (eg, oolong tea). However, there are difficulties in terms of equipment and technology in adopting this nitrogen filling technique, and it is desired to employ DI cans without nitrogen filling.

[0005] Under these circumstances, the development of technologies other than nitrogen encapsulation technology has been advanced. For example, there is a method of adding beads to the side wall of a can to increase the rigidity of the side wall (Special Publication No. 54
No.-14552, No. 54-14553, JP-A-63-
125149 etc.).

As described above, there are two methods for using DI cans for non-carbonated beverages: the nitrogen filling method and the side wall bead processing method. However, it is currently difficult to employ the nitrogen filling method, and the side wall bead processing method has a problem in that coating defects occur on the side wall surface of the can during bead processing.

[0007] Therefore, the present inventors investigated the positive pressure (
Approximately 3 x 10-1 MPa), and the internal pressure is atmospheric pressure (
The inventor invented a DI can having a can bottom shape in which the can bottom deforms to the inside of the can when the pressure becomes less than about 9.8 x 10-2 MPa), and the internal pressure becomes higher than atmospheric pressure. It was proposed in the issue.

[0008] However, although this DI can uses the pressure difference between the inside and outside of the can at room temperature to cause spontaneous deformation of the can bottom, the following problems occur. (1) Due to variations in the thickness and strength of the material,
Quality control is difficult because the same deformation does not occur over the same elapsed time. (2) The shape of the can bottom after deformation may not be axially symmetrical with respect to the central axis of the can body, which impairs the aesthetic appearance. (3) If only the pressure difference between the inside and outside of the can is used, the internal volume will only decrease by about 15cm3 at most, and the inside of the can will be about 1cm at room temperature.
The positive pressure is only about 5 x 10-2 MPa. When this can is cooled to below room temperature, the pressure inside the can further decreases as the temperature changes, making it easier for dents to form on the side walls of the can. (4) When the can side wall is set to 0.15 mm or less, if the amount of reduction in internal volume is increased, that is, the deformation of the dome portion is large, dents in the can side wall occur before can bottom deformation.

The present invention solves the above-mentioned problems of the prior art and provides a method for making a DI can for non-carbonated beverages in which the interior of the can filled with non-carbonated beverages is reliably provided with sufficient positive pressure. The purpose is to

0010

[Means for Solving the Problems] As a result of intensive research into new measures to solve the above problems, the present inventors decided to make the can bottom shape a specific shape, and to prevent the inside of the can from becoming negative pressure. It was discovered that by forcibly deforming the can bottom dome, positive pressure is created inside the can, and after that, sufficient positive pressure is maintained to prevent denting under any environment, and the present invention has now been completed. be.

[0011] That is, in the present invention, in any cross-sectional shape passing through the central axis of the can body of a DI can manufactured from plate material,
A can bottom leg part that is convex to the outside of the can from the can side wall, a can bottom counter part that is convex to the inside of the can, and a can bottom dome part that is convex to the outside of the can. D has a can bottom shape that connects smoothly.
After hot filling a can with a non-carbonated beverage, attaching a lid and sealing the can, the can bottom becomes convex on the outside with the pressure inside the can maintained higher than the pressure outside the can. The gist of this invention is a method for manufacturing a DI can for non-carbonated beverages, characterized in that the dome portion is pushed from the outside of the can with a punch whose head is in the shape of an axially symmetrical convex curved surface, and deformed into a convex shape inside the can. be.

The present invention will be explained in more detail below.

[Effect]

[0013] Non-carbonated beverages such as fruit juice and coffee are sometimes sealed after hot filling (approximately 90°C) and subjected to retort treatment (approximately 120°C) for sterilization. In this case, the internal pressure of the can is approximately 3 x 10-1 due to the increase in liquid and temperature.
MPa. Therefore, it is necessary that the can body can withstand this internal pressure.

[0014] The DI can used in the present invention has a can bottom leg that is convex from the can side wall to the outside of the can in any cross-sectional shape passing through the central axis of the DI can manufactured from plate material. This DI can has a can bottom shape in which a can bottom counter part that is convex on the inside of the can and a can bottom dome part that is convex on the outside of the can are connected to each other smoothly.

This DI can body has a can bottom shaped as shown in FIG. 1, and when high positive pressure is applied to the can body, a force is generated at the can bottom that moves the can bottom dome in the direction of the central axis of the can body. acts, and this force is transmitted to the bottom leg of the can. At this time, the can bottom leg, which has a convex shape on the outside of the can, can prevent the dome from bulging. Although the shape of the can bottom leg is not particularly defined, the smaller the radius of curvature, the less likely the dome will bulge.

Furthermore, by forming the can bottom dome in a convex shape on the outside of the can, a large change in capacity can be caused when the can bottom dome, which will be described later, becomes convex on the inside of the can. Although the shape of this part is not particularly specified, the radius of curvature and depth are changed depending on the required positive pressure inside the can.

[0017] The can bottom counter part, which has a convex shape on the inside of the can between the can bottom leg part and the can bottom dome part, has the function of transmitting the pressure applied to the can bottom dome to the can bottom leg part during retort processing, and also has the function of transmitting pressure applied to the can bottom dome to the can bottom leg part during retort processing. After the can bottom dome is deformed, it functions to smoothly connect the can bottom dome shape that is convex on the inside of the can with the can bottom leg shape.

[0018] After hot filling a DI can body having such a can bottom shape with a non-carbonated beverage, and further attaching a lid and sealing the can body, or after subsequent retort treatment at about 120°C, the can is left as it is. As a result, the temperature of the liquid and gas inside the can decreases, and the pressure inside the can becomes lower than the pressure outside the can. At this time, if the can side wall is thin (0.150 mm or less), a dent will occur in the can side wall, or if the can side wall is sufficiently thick, the can bottom dome will be inverted. However, when reversing the can bottom dome, it is difficult to cause the same deformation in the same elapsed time, and the deformation is also difficult to be axially symmetrical with respect to the central axis of the can.

Therefore, the temperature inside the can is increased using retort treatment, etc., and after the retort treatment, with the pressure inside the can maintained higher than the pressure outside the can, the bottom dome of the can is heated as shown in FIG. A punch whose tip has an axially symmetrical convex curved surface is pushed in from outside the can. Although the shape of the punch tip is not particularly specified, in order to obtain the dome effect of the molded can, which will be described later, it is desirable that the contact portion with the can be a part of a spherical shape.

In this case, the can bottom dome, which has a convex shape on the outside of the can, gradually deforms as the punch is pushed in, and finally becomes a convex shape on the inside of the can, as shown in FIG. Although there is a decrease in gas pressure as the temperature inside the can decreases, the total volume of the can decreases significantly due to this deformation of the can bottom dome, and the pressure inside the can becomes positive. The inwardly convex shape of the deformed can extending from the can bottom counter to the can bottom dome is such that the can bottom dome is unlikely to be deformed even if the pressure inside the can changes due to the dome effect.

Further, the pushing force of the punch is usually determined by the buckling strength (1.5 to 2.0×10
3N), but since the inside of the can is sealed, the can body will not buckle.

Next, examples of the present invention will be shown.

[0023]

[Example] 3004 alloy hard plate material (plate thickness 0.34mm
) was subjected to DI processing to produce a can of 66 mmφ x 72 mmh (total volume 230 cm3). Side wall thickness is 0.15mm
The shape of the can bottom is shown in Figure 1. Here, the leg radius is 1
．． 5mm, and the dome radius is

Changes were made as shown in Table 1. The center of the can bottom dome extends to the same height as the legs.

After putting 200g of hot water at 90°C into this can, and keeping it at 95°C, the punch head has a radius of curvature of 50mm, the shoulder of the punch has a radius of curvature of 1.5mm, and these are smooth. With an axisymmetric convex curved shape connected to
Using a punch whose cylindrical portion has a radius of 50 mm, the can bottom dome was pushed in from the outside of the can. After deformation, the reduction in total volume and the pressure inside the can were measured from the volume of the can. The results are also shown in Table 1. In addition, as a comparative example, Table 1 also shows the results when the samples were left to cool naturally without being deformed with a punch after hot filling.

As is clear from Table 1, in all of the examples of the present invention, there is positive pressure inside the can, there is no dent in the side wall of the can, and the shape of the can bottom after deformation is axially symmetrical and beautiful.

[0026]

[Effects of the Invention] As detailed above, according to the present invention,
After hot filling a non-carbonated beverage into a DI can with a specific can bottom shape, a punch with an axially symmetrical convex curved head is pushed into the can bottom dome to ensure filling inside the can compared to conventional methods. It is possible to create a positive pressure in the can and also to cause axially symmetrical deformation, making it possible to realize a DI can for non-carbonated beverages.

Furthermore, the DI can body for non-carbonated beverages of the present invention can replace the conventional three-piece can with a two-piece (DI) can, which can significantly reduce the weight of the can and also Cans are also effective in saving resources through recycling.

In addition, the side walls of DI cans can be made thinner, making it possible to further reduce the cost of cans, making them inexpensive and easy to apply to non-carbonated beverages; The features (odorless, recyclability) can be fully utilized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the shape of the bottom of a can body in the present invention.

FIG. 2 is a diagram illustrating deformation of the can bottom according to the manufacturing method of the present invention, showing a state in which the can bottom dome is pushed in with a punch.

FIG. 3 is a diagram illustrating deformation of the can bottom according to the manufacturing method of the present invention, showing a state in which the can bottom dome is pushed into the inside of the can by a punch.

[Explanation of symbols]

1 Can side wall 2 Can bottom legs 3 Can bottom counter part 4 Can bottom dome part 5 Punch 51 Punch head 52 Punch shoulder 53 Punch cylindrical part

Claims (1)

[Claims] Claim 1: In an arbitrary cross-sectional shape passing through the central axis of the can body of a DI can manufactured from plate material, a can bottom leg portion having a convex shape on the outside of the can from the can side wall and a convex portion on the inside of the can connected thereto. A non-carbonated beverage is hot-filled into a DI can having a can bottom shape in which a can bottom counter portion having a shape and a can bottom dome portion having a convex shape on the outside of the can are connected smoothly, and After the lid is attached and sealed, with the pressure inside the can maintained higher than the pressure outside the can, the can bottom dome, which has a convex shape on the outside of the can, is inserted into the can with an axisymmetric convex curved head. DI for non-carbonated beverages characterized by pushing from the outside of the can with a punch and deforming it into a convex shape inside the can.
How to make cans.