JPH01213148A - Integrally-formed pressure-resistant can and its manufacture - Google Patents

Abstract

PURPOSE:To obtain such a bottom structure that load collapse is not caused even if cans are piled after being sealed, and that may not be easily caused due to internal pressure even though the bottom is comparatively thin by a method wherein a circular projection consists of an outer wall in a short cylindrical shape and a bottom wall of a cross-sectional semicircular shape, the outer wall is in contact with a tapered portion via a first curve, and the inner wall is in contact with a panel portion via a second curve. CONSTITUTION:A circular projection 15 has a u-shaped cross section, and its outer wall portion 15a is short cylinder-shaped, which is in contact with a tapered portion 19b via a curve 20. Similarly, an inner wall portion 15b is in contact with the outer wall portion 15a via a semicircular bottom wall portion 15c while it is in contact with a panel portion 18 which is recessed toward inside in a semispherical shape via a curve 21. Since the gradient and size of the tapered portion 19b is specified so that the outer diameter of the outer wall portion 15a is a little smaller than the inner diameter of a double seaming end 22, a similar sealed can 11' can be mounted on a sealed can 11 so that the circular projection 15' of the can 11' is in contact with a top portion 13 of the sealed can 11, preventing collapse of the load.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is an integrally formed can formed by drawing or drawing, kneading, ironing, etc., and is suitable for storing positive pressure contents such as beer and carbonated drinks. This invention relates to a suitable integrally molded pressure can and its manufacturing method.

(Prior Art) Recently, as the bottom structure 2 of an integrally molded pressure can, a structure having an annular protrusion 3 having a V-shaped cross section as shown in FIG. Showa 53-1
(See Publication No. 35271). An external slope portion 3 on the annular protrusion 3
A is provided after the pressure can 1 is sealed, as shown in the figure.
When stacking on similar sealed pressure cans 1' in multiple stages, the annular protrusion 3 is placed inside the double seam part 4 of the lower sealed pressure can 1'. This is to prevent this from happening.

(Problem to be solved by the invention) In the case of such a conventional bottom structure 2, for example, 7 kg/l
In order to prevent battering from occurring even under a relatively high internal pressure of ．． It had to be as thick as . Therefore, there was a problem that a large amount of material was used, leading to high costs.

An object of the present invention is to provide an integrally molded pressure can having a bottom structure that does not cause the cylindrical part to move even when stacked under pressure after sealing and is less likely to cause pack rings due to internal pressure even if the can is relatively thin, and to provide a method for manufacturing the same. With the goal.

(Means for Solving the Problems) The integrally molded pressure can of the present invention has a cylindrical body main part and an inverted truncated conical cheek part connected to the lower part of the body main part; and a bottom portion having a U-shaped annular projection connected to the tapered portion and a panel portion located inside the annular projection; The circular bottom wall part and the outer wall part l
d is connected to the tapered portion via a first curvature portion, and the inner wall portion is connected to the panel portion via a second curvature portion.

Preferably, the ratio of the cross-sectional length of the tapered portion to the height of the outer wall portion is about 1-2.

The above integrally molded pressure can having a body and a bottom is an integrally molded preform can comprising a cylindrical body wall main part, a body wall having an inverted truncated conical part connected to the lower part thereof, and a flat bottom part. The outer surface and the inner surface of the inverted truncated conical section are respectively slid between the draw die and the presser pad so that the inverted truncated conical section and the bottom wall are connected via the first curvature section, and A first step of forming a pre-bottom portion where the panel portion and the bottom wall portion are connected via the second curvature portion by a die center and a noyanch center provided inside the draw die and the presser pad, respectively; The die center and the punch center are
The outer wall is held between the first curvature part and the bottom wall by sliding the inverted truncated conical part between the draw die and the presser pad. a second step of forming a pre-outer wall portion that is higher than the inner wall portion by the height of the inner wall portion; and fixing the inverted truncated conical portion to the draw die and the presser/rad,
- A third step of holding the octater in the state of the second step and moving it toward the presser pad by the height of the inner wall to form the outer wall and the inner wall at a predetermined height. It can be formed by

(Function) In the integrally molded pressure can with the above shape, the outer wall of the annular protrusion is connected to the tapered part, so the outer diameter of the outer wall should be set smaller than the inner diameter of the double-sealed part after sealing. By placing the annular protrusion of the sealed can on the lid of another sealed can of similar structure, or by placing the Chee-Ya part on the double seam part of the other sealed can, It can be stacked in multiple stages without causing the cylindrical part to warp.

Since the annular protrusion has a U-shaped cross section and the inner wall extends in the axial direction in a short cylindrical shape, no downward component of internal pressure acts on the inner wall. Therefore, even if the bottom portion is relatively thin, pack rings are unlikely to occur in the panel portion. This puck ring resistance can be greatly improved by making the radius of curvature of the inner surface of the bottom wall as small as possible within the moldable range, for example, about 0.5 m. This is because the smaller the radius of curvature, the smaller the downward component of the internal pressure at the bottom wall.

Similarly, because the outer wall has a short cylindrical shape and extends in the axial direction, and because of the arch effect, buckling of the chip and outer wall is unlikely to occur even if the wall is relatively thin. By setting the ratio of the cross-sectional length of the tapered portion to the height of the outer wall portion to about 1 to 2, the above-mentioned arch effect (arch effect) is further enhanced.

When forming a bottom portion having an annular protrusion with a U-shaped cross section by drawing and overhanging only, cracks and Damage is likely to occur.

In the case of the manufacturing method of the present invention, the portion corresponding to the annular protrusion formed by drawing and extrusion in the first step is substantially only the bottom wall, and the protrusion height is low. Therefore, cracks and damage are unlikely to occur during the first step. Since only a slight drawing process is performed in the second step, cracks and breakage are unlikely to occur. After the second step and the third step, the inner raised part is separated to a predetermined height.

(Example) In FIG. 1, 11 is a so-called canned can, which is a sealed can formed by filling an integrally molded pressure-resistant can 12 with a positive-pressure content 13, such as beer, and then sealing it by double-sealing the lid 14. . Although not shown, the lid 14 usually has a score portion defining an opening, and a pull tab for opening the score portion by tearing the score portion.

The pressure can 12 is made of tin-plated steel plate, tin-free steel,
After forming a cup-shaped preform can by drawing a circular metal blank made of an aluminum alloy thin plate or the like, a bottom part 16 having an annular protrusion 15 is formed by the method described later, and then a well-known method is formed on the upper part of the body part 19. The two-stage neck-in portion 17 and the flange portion are formed by the method described above.

The body of the pressure can 12] 9, the cylindrical body main part 19a and the inverted truncated conical cheek part that contacts the lower part of the body main part 19 via the curved part 19c], 9 b. We are prepared.

Bottom] 6 is the annular protrusion 15 and its inner mother flannel part]
It's 8 years old. In FIG. 1, the panel portion] 8 is spherically recessed inward in order to withstand internal pressure.

The annular protrusion 15 has a U-shaped cross section, and its outer wall 15
a has a short cylindrical shape, and the tapered part 1 is connected to the tapered part 1 through the curved part 2o.
Connected to 9b. The inner wall portion 15b, which also has a short cylindrical shape, connects to the outer wall portion 1.5a via the bottom wall portion 15c, which has a semicircular cross section.
, and is connected to the spherically inwardly concave flannel portion 18 through the curved portion 21 .

Since the slope and dimensions of the tapered portion 19b are determined so that the outer diameter of the outer wall portion 5a is slightly smaller than the inner diameter of the double-sealed portion 22, similar sealing is achieved as shown in FIG. The can 11' can be placed on the sealed can r q ) 1.1 so that its annular protrusion 15' contacts the lid 14 of the sealed can r q ) 1.1, thereby preventing the cylinder from collapsing.

The wall thickness of the tapered portion 19b and the bottom portion 16 is usually about 0.15 to 0.2 mm when the blank is made of tin-plated steel or tin-free steel in a can for carbonated drinks such as cola.
When it is made of aluminum alloy thin plate, it is usually about 025
~0.30g.

In the case of FIG. 1, the cross-sectional length of the tapered portion 19b and the height of the outer wall portion 15a are approximately equal. Therefore, due to the so-called Darch effect, even if the tapered portion 19b and the outer wall portion 15a are relatively thin, there is no risk of buckling outward due to internal pressure.

The smaller the radius of curvature r1 (see FIG. 5) of the inner surface of the bottom wall portion 15C is, the more difficult it is to cause buckling due to the internal pressure of the iP channel portion 18, which is preferable, but on the other hand, it becomes difficult to mold.

Therefore, the radius of curvature rI is usually about 04 to 1.0. ,l
It is. The height h (see FIG. 5) of the inner wall of the folding section 5b is usually about 3 to 8 mm.

Figures 2, 3, 4 and 5 show the bottom 1 of the pressure can] 2
6 shows the molding process. 25(]0) is a punch center, 26 is a die center, 27 is an annular presser pad, 28 is an annular fixed draw die, and 29 is an annular fixed draw die.
is a preform can formed by drawing.

The preform can 29 has a body wall main portion 29a having the same diameter as the body main portion 19 of the pressure can 12 to be formed, and an inverted truncated conical portion having the same length (1) and slope angle as the tapered portion 19b. 30, and flat? It has a tom portion 31.

The presser pad 27 and the draw die 28id each include a presser surface 27a and a draw surface 28& that clamp the inverted truncated conical portion 30 from the inner and outer sides. The outer diameter of the presser foot/glad 27 is the same as the main part 29 of the body wall of the preform can 29.
The inner diameter of the cavity inner surface 28b of the die 28 is substantially equal to the inner diameter of the annular protrusion 1 to be formed.
5. The hold-down pad 27 is axially biased by a spring or air cylinder (not shown), so that the inverted truncated conical portion 30
is configured to press against the draw surface 28a.

Punch center 25 inserted through the inside of presser/glad 27
The outer diameter of the outer wall portion 15a is smaller than the outer diameter of the annular protrusion 15.
is substantially equal to a value that is twice the thickness of . The punch center 25 is provided with an annular convex portion 25a1 and a flannel portion forming surface 25b connected to the annular convex portion 25a via a corner portion 25c at the lower end.

The annular convex portion 25a has a U-shaped cross section, and the radius of curvature of the annular bottom portion 25a1, which has a semicircular cross section, is set equal to the radius of curvature r1 of the inner surface of the bottom wall portion 15c to be formed.

The inner diameter of the short cylindrical inner peripheral surface 25a2 of the annular protrusion 25a is the same as the inner diameter of the annular protrusion 15 to be formed.
The thickness is set to be twice as large as the thickness of the The height H (FIG. 2) of the annular convex portion 25a is determined by the radius of curvature r2 of the inner surface of the curved portion 21 to be formed and the radius of curvature r1.
, and the depth d of the inner surface of the panel portion 18 inwardly recessed from the curved portion 21 (see FIG. 3).

The die center 26, whose forming part is cylindrical, has a cylindrical surface 2 whose diameter is substantially equal to the inner diameter of the annular projection 15 to be formed.
6a, and a channel forming surface 26b connected to the cylindrical surface 26a via a curved portion 26c. Curvature part 26
The radius of curvature r3 of c is determined to be substantially equal to the radius of curvature of the outer surface of the curved portion 21 to be formed (see FIG. 5). In this embodiment, the panel molding surface 25b is flat, while the panel molding surface 26b of the die center 26 is flat.
has an upwardly convex dome-like shape.

The punch center 25 is configured to be able to move up and down by a crank mechanism or a pneumatic or hydraulic device (not shown), while the die center 26 follows the up and down movement of the punch center 25 by a spring mechanism or a pneumatic mechanism (not shown). It is configured to be able to move up and down.

In the above arrangement, first, as shown in FIG. Set can 29.

Next, as shown in FIG. 3, lower the Sonchi center 25 until the panel forming surface 25b comes into contact with the bottom portion 31, and slide it inwardly and downwardly along the draw surface 28a of the inverted truncated conical portion 30. The panel part 18 is concave inwardly into a spherical shape, and the bottom wall part 15C is connected to the panel part 18 via the curvature part 21, by drawing the bottom part 31 with the die center 26 and the stretching process of the bottom part 31 with the die center 26. Puri bottom part 32,
In addition, a curved portion 20 is formed. Since the degree of overhang at this time is small, cracks or breaks are unlikely to occur in the bottom wall portion 15C even if the radius of curvature r1 is small.

Next, as shown in FIG. 4, while holding the pre-bottom part 32 in the state shown in FIG. by sliding the inverted truncated conical part 30 along the draw surface 28a, squeezing the lower part of the main body wall part 29a of the preform can 29, and creating a space between the curved part 20 and the bottom wall part 15c. The outer wall portion 15a to be formed also forms a short cylindrical pre-outer wall portion 33 which is as high as the height h of the inner wall portion 15b to be formed.

Since processing force is not substantially applied to the glue bottom portion 32 including the bottom wall portion 15e, there is no fear that the pre-bottom portion 32 will crack or break.

Next, by increasing the pressing force of the presser foot/rod 27 and fixing the inverted truncated conical portion 30 between the presser surface 27a and the draw surface 28a, as shown in FIG. 25 and the die center 26, the punch center 25 and the die center 26 are simultaneously raised to a height equal to the height h of the inner wall portion 15b to be formed. Therefore, the material for a height h from the pre-outer wall part 33 goes around the bottom wall part 15e and moves to the inner wall side, and the inner wall part 1 of a predetermined height
5b and an outer wall portion 15a are formed.

At this time, the inverted truncated conical portion 30 has tapered portions 19b and 75,
The tapered portion 19b connects to the outer wall portion 1.5a via the curvature portion 20.
Connect with. In the manner described above, the pressure can 2 having the tapered portion 19b, the annular protrusion 15, and the panel portion 18 is formed. When forming the inner wall portion 15b, only bending force is applied to the material and no tensile stress is applied to the material, so there is no risk of cracking or breaking.

The present invention is not limited to the above embodiments,
For example, when forming a panel part that is spherically inwardly recessed, the panel part forming surface (25b) is formed by forming a 7No inch center (25) that is spherically inwardly recessed, and a panel part forming surface (25b) that is spherically inwardly recessed.
A die center (26) may be used in which the die center (26) is concave outward in a spherical shape corresponding to the panel portion formation J25 b). Further, the panel portion may be flat, and in this case, the panel portion forming surfaces (25b, 26b) have a punch center (25) and a die center (25) with corresponding planar shapes.
26) is used. Further, the preform can may be an integrally formed can formed by drawing, kneading, and pressing.

(Concrete example) A specific example will be described below.

Plate thickness (11811 m1 diameter 180 mm, thickness 3 on the inner and outer surfaces)
A circular blank of tin-free steel (hardness DR-9) on which a 0 μm vinyl baking coating was formed was drawn to produce a material with a height of 122 mm, an outer diameter of the main portion 29a of the trunk wall portion of 66 mm, and a bottom portion 31. Preformed cans 29 were prepared in which the diameter of the inverted truncated conical part 30 was 50, the length t of the inverted truncated conical part 30 was 5, and the radius of curvature of the inner surface of the curved part 29b was 1 to 3.

This Noriform can 29 is shown in FIGS. 2 and 3.

The bottom part is machined as shown in FIGS. 4 and 5, and the radius of curvature of the outer surface of the curved part 20 is 05' Mfl, and the outer wall part 15a is
The height of 15 parts is 15, and the radius of curvature rl of the inner surface of 15 parts of the bottom wall part is 0.
Column 5, the height h of the inner wall portion 15b is 2 mm, the radius of curvature of the outer surface of the curvature portion 21 is 0.5 mm, and the panel portion 18 is concave inward in a spherical shape (radius of curvature 50 mm). A bottom portion 16 was formed. No cracks or damage occurred in the annular protrusion 15 during molding. Next, a two-stage neck-in part 1 is attached to the open end.
7 and a flank portion were formed to produce a pressure can 12.

After filling this pressure can with water, the lid portion 14 was double-sealed to produce a sealed can 11. A pressure test was conducted by making a hole in the lid of the sealed can 11 and applying 7 kg/crn of air, but no buckling was observed in the panel portion 18, the chi 74 portion 19b, and the outer wall portion 15a. , was normal.

For comparison, the can 1 having the bottom structure 2 shown in FIG.
It was produced from the same blank as above by drawing and doming, as well as two-stage necking and seven-lunge processing.

The height and body diameter of the can 1 are the same as those of the pressure can 12. The diameter of the grounding part 3b of the annular protrusion 3 is 52 cm, and the outer slope part 3a is
The length is 8-1 The radius of curvature of the inner surface of the lower curvature part 3C is 1.5
Mn, the length of the inner slope part 3d is 6, l, the angle θ with the axial direction is 10 degrees, and the radius of curvature of the outer surface of the curved part 3e is 2.
wI+% The radius of curvature of the outer surface of the inner concave groove portion 3f was 50 mm.

When this can 1 was sealed with the lid in the same manner as described above and a pressure test was conducted, the panel part 3 was subjected to an air pressure of 5 kg/Crn.
f buckled.

(Effects of the Invention) The integrally molded side pressure canner of the present invention has the advantage that the cylinder part does not move even when stacked under pressure after sealing, and has a bottom structure that does not easily buckle due to internal pressure even if the wall is relatively thin. play.

In order to improve pressure resistance, the manufacturing method of the present invention provides the above-mentioned surface even when the inner and outer walls of the annular protrusion of the pressure can are made relatively high and the radius of curvature of the inner surface of the bottom wall is made small.
This has the effect that cracks and breakage are less likely to occur during molding.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of a sealed can formed by sealing the integrally molded pressure can of the present invention, Fig. 2, Fig. 3, Fig. 4, and Fig. 5.
The figure is a vertical cross-sectional view of the main part showing the process of manufacturing the pressure can of Figure 1, Figure 2 is a diagram showing the state immediately before the bottom is formed, and Figures 3, 4, and 5 are the bottom. FIG. 6, which is a drawing showing the first, second, and third steps of molding, is a vertical cross-sectional view of a main part of a conventional integrally molded pressure can. 129.9 integrally molded pressure can, 15... annular protrusion, ]
, 5a...outer wall part, 15b...inner wall part, 15C...
...Bottom wall part, 16...Bottom part, 18...Gunnel part,
19... body part, 19a... main part of body part, 19b... 2nd part of chi, 20... curvature part of 1st, 21 ・2nd curvature part 1, 25... yanch center , 26... Die center, 27... Embossing/e7 do, 28... Draw die, 29... Preform can, 29a... Body wall main part, 30... Inverted truncated conical part , 31... bottom part, 32...
... Puri bottom, 33... Puri outer wall part Fig. 2 Fig. 4/2 U. /-30 Figure 3

Claims (3)

[Claims] (1) A cylindrical body main part, a body part having an inverted truncated conical tapered part connected to the lower part of the body main part, an annular protrusion part having a U-shaped cross section connected to the tapered part, and a bottom portion having a panel portion located inside an annular projection portion, the annular projection portion comprising short cylindrical outer and inner wall portions and a bottom wall portion having a semicircular cross section, the outer wall portion having a first curvature; The integrally molded pressure can is connected to the tapered portion through a curved portion, and the inner wall portion is connected to the panel portion through a second curved portion. (2) The ratio of the cross-sectional length of the tapered part to the height of the outer wall is approximately 1 to
2. The integrally molded pressure can according to claim 1, wherein: (3) A method for manufacturing an integrally molded pressure can according to claim 1, comprising:
The outer and inner surfaces of the inverted truncated conical part of an integrally molded preform can, which includes a main part of the cylindrical body wall part, a trunk wall part having an inverted truncated conical part connected below the main part, and a flat bottom part, respectively. , slide it between the draw die and presser pad,
The draw die and the presser are connected to the pre-bottom part where the inverted truncated conical part and the bottom wall part are connected via the first curvature part, and the panel part and the bottom wall part are connected via the second curvature part. A first step of forming the pad with a die center and a punch center provided inside the pad; the die center and the punch center are held in the state at the end of the first step and pushed into the draw die to form an inverted truncated conical shape. A second pre-outer wall portion that is higher than the outer wall portion by the height of the inner wall portion is formed between the first curved portion and the bottom wall portion by sliding the part between the draw die and the presser pad. step; fix the inverted truncated conical portion between the draw die and the presser pad, hold the die center and the punch center in the state of the second step, and adjust the height of the inner wall toward the presser pad. A method for manufacturing an integrally molded pressure can, comprising a third step of forming the outer wall portion and the inner wall portion of a predetermined height by shifting the outer wall portion and the inner wall portion by a predetermined height.