JPH035033A - Method for forming botton part in integrated formed can - Google Patents

Abstract

PURPOSE:To prevent the development of radial wrinkle by pressing a part of inner side from circumferential edge part with a core die having spherical pressing face while holding and pressing bodies facing the circumferential edge part of a center panel to form a spherical recessed part. CONSTITUTION:The circumferential edge part 4a of the center panel 4 at bottom part 3, 7 of an integrated formed can 1 of deep drawing formed can, etc., is pressed with at least one pair of the press bodies having the pressing face corresopnding to the circumferential edge part of the center panel 6 to be formed and mutually facing to form this circumferential edge part. Successively, while holding this curcimferential edge part with gap between the pressing bodies, the part of inner side from the circumferential part 6a of the panel 4 is pressed toward inner part of the can with the core die 18 having the spheri cal pressing face to form the center panel recessed as spherical state at this bottom part. By this method, the center panel recessing as the spherical state at the bottom part of the integrated forming can, can be formed without substan tially developing the radial wrinkle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a drawing can, a drawing-sliding can (DI can)
This invention relates to a method for forming a spherically concave central nozzle on the bottom of a one-piece molded can.

(Prior art) One-piece molded cans such as draw-molded cans are often filled with positive internal pressure liquids (liquids that generate an internal pressure higher than atmospheric pressure after the container is filled and sealed), such as carbonated beverages. , in order to prevent the royal stability from being compromised by the bulge of the bottom due to relatively high internal pressure (e.g. 7 kg) after sealing, the part of the bottom inside the annular grounding part is usually spherical, i.e. domed. It is formed in a concave shape.

From the viewpoint of reducing material costs, it is desirable to make the bottom part thinner and to compensate for the decrease in strength due to the thinner part by using a harder material. However, before the spherical recess is formed, the bottom part (usually flat) is thin like this.
If it is hard, the bottom part is simply pressed using a conventional method using a so-called doming punch (which has a spherical pressing surface corresponding to the recess to be formed and corresponds to the core die 18 in this specification). If a spherical recess is formed by this, radial wrinkles are likely to occur near the periphery of the recess. These wrinkles are more likely to occur as the radius of curvature of the recess becomes smaller.

These wrinkles not only impair the appearance of the can, but also cause the problem of lowering the puck-ring resistance against internal pressure at the bottom.

(Problems to be Solved by the Invention) The present invention is capable of forming a spherical depression in the bottom without substantially generating radial wrinkles even when the bottom of a one-piece molded can is relatively thin and hard. The purpose is to provide a method for forming a central panel.

In addition to the above case, the present invention further provides that the center to be formed /-? An object of the present invention is to provide a method for forming a spherically concave central panel at the bottom of a one-piece can without substantially generating radial wrinkles even when the radius of curvature of the flannel is relatively small. shall be.

(Means for Solving the Problems) The present invention provides that the peripheral edge of the center panel at the bottom of a one-piece molded can has a pressing surface having a shape corresponding to the peripheral area of the center panel to be formed, and faces each other. and forming a spherical pressing surface on the inner part of the bottom part from the peripheral part while pressing the peripheral part between the pressing bodies. The present invention provides a method for forming the bottom of a one-piece molded can, characterized in that a spherically concave center groove is formed in the bottom by pressing against the internal force of the can with a core die.

(Function) When pressing the bottom with a doming punch to form a spherical recess, radial wrinkles occur around the periphery of the recess because the center of the bottom first comes into contact with the doming punch during the above formation. However, it is thought that this is because when the contact portion gradually expands toward the peripheral edge after that, compressive force in the circumferential direction acts on the vicinity of the free peripheral edge that has not yet contacted the doming punch.

In the case of the present invention, while the peripheral edge of the center panel is pressed by opposing pressing bodies, a portion inside the peripheral edge (hereinafter referred to as part A) is pressed by a core die having a spherical pressing surface.
Since the portion A is formed into a spherical recess by pressing, radial wrinkles do not occur because the peripheral edge is restrained.

Since the pressing body has a pressing surface of a shape corresponding to the peripheral part of the spherical center panel to be formed, the peripheral part of the center funnel pressed by the pressing body is - Formed around the mother flannel.

Therefore, this peripheral portion and the portion inside the peripheral edge formed in the spherical recess can form a central panel that is recessed in a spherical shape as a whole.

(Example) In FIG. 1, reference numeral 1 denotes a one-piece molded can, for example, a plate having a thickness of about 0.13-0.0 μm and having a polyethylene terephthalate film of about 20-30 μm attached on both sides. 18m
m tinnery steel (electronic acid treated steel plate)
It is formed by drawing and re-drawing a circular blank, and is made up of a cylindrical body 2, an inclined part 3 extending inwardly and downwardly, and a bottom part 5 consisting of a flat center panel 4.

FIG. 5 shows a one-piece molded can 1 in which a center groove 4 is formed into a spherically concave center groove 6.
The bottom part 7 is connected to the lower end of the body part 2.

(5) an outer wall portion 8 concave in an arcuate cross-section and extending diagonally downward inward; an annular bottom wall portion 9 connected to the lower end of the outer wall portion 8 and preferably having an arcuate cross-section with a small radius of curvature and forming a ground contact portion; It is provided with a short cylindrical inner wall part 10 that rises in the axial direction from the upper end of the bottom wall part 9, and an E-flank 6 in the center.

In FIG. 1, 12 is a middle mold, 13 is a lower mold, and 14 is an outer wall forming tool. The medium die 12 includes a core punch 15 having a peripheral wall portion 15a that can be inserted into the body portion 2 in a substantially snug manner, and a suppressor 16 provided in a cylindrical recess 15b formed at the bottom of the core punch 15. The lower end 15a1 of the peripheral wall 15a of the core punch and the inner peripheral surface 15b of the recess 15b
An arcuate section 15c having a shape corresponding to the outer wall section 8 to be formed is formed between the curved sections 11 connected to the lower ends of the outer wall section 1.

The lower surface 16a of the pressing body 16 has a spherical shape corresponding to the shape of the center panel 6 to be formed.

The suppressor 16 is suspended from the core punch 15 via a spring 17, and its lower end 16b is normally located slightly above the lower end of the core punch 15 (6).

Note that the lower surface of the suppressor 16 is, for example, the one-dot chain line 16 in FIG.
As shown by a', the inner side of the portion facing the upper end 19a1 of the ring die 19 may be recessed inward than the spherical lower surface 16a, that is, upwardly.

The lower die 13 includes a core die 18 and a ring die 19 inserted into the core die 18. The upper surface of the ring die 19 extending upward from the inside, that is, the pressing surface 19a, has a shape corresponding to the peripheral portion 6a of the central panel 6 to be formed. On the other hand, the upper surface of the core die 18, that is, the pressing surface 1
8a has a spherical shape corresponding to a portion 6b (hereinafter referred to as central portion 6b) of the central panel 60 that is inside the peripheral portion 6a of the central panel 60 to be formed.

The lower surface of the ring die 19 and the fixed support 2 of the core die 18
A spring 21 is provided between 0 and 0, and the pushing force of the spring 21 normally engages the inward protruding part 19b of the ring die 19 and the outward protruding part 18b of the core die 18, so that the ring die 19 The upper end 19a1 of the pressing surface 19a of
is positioned slightly higher than the top 18a1 of the pressing surface 18a of the core die 18. Further, the height of the ring die 19 is determined such that when the ring die 19 is lowered and its lower surface is in contact with the support 20, the pressing surface 18a and the pressing surface 19a form a common spherical part. (See Figure 4).

The compressive strength of the spring 21 is determined to be smaller than that of the spring 17. Further, the diameter of the outer circumferential surface 19c of the ring die 19 is set smaller than the inner diameter of the inner circumferential surface 15b1 of the four parts 15b by about 1.5t to 2.0t (t is the thickness of the center panel 4).

The outer wall forming tool 14 includes an annular mold 22 having a molding surface 22a having a shape corresponding to the outer wall 8 to be formed, and an inner protrusion 24a that can engage with an outer protrusion 22b of the mold 22. A cylindrical holding body 24 is provided. The lower surface of the support 23 of the mold 22 and the bottom of the fixed holder 24 (
(not shown), a spring (not shown) or the outward protruding part 22b and the inward protruding part 24a engage with each other, and as shown in FIG. It is configured to be located at a slightly higher predetermined position.

The center panel 6 is formed using the above tools as follows. After the middle mold 12 is raised and the one-piece molded can 1 coated with lubricating oil on the inner and outer surfaces is inserted into the middle mold 12, the middle mold 12 is lowered. FIG. 1 shows the middle mold 1 reaching the position where the inclined portion 3 of the one-piece molded can l and the molding surface 22a of the mold 22 start contacting.
2 indicates a lowered state.

As the middle die 12 continues to descend further, the inclined portion 3 is pressed by the arcuate portion 15c of the core punch 15 and the molding surface 22a of the mold 22, forming an outer wall portion 8 having an arcuate cross section. be done. At the same time, the peripheral edge 4a (FIG. 1) of the center panel 4 is pushed into the recess 15b by the ring die 19 until it comes into contact with the lower surface 16a of the pressing body 16, thereby forming the peripheral edge 6a (9) of the center panel 6 to be formed (9). It is formed in the shape shown in Fig. 5). At this time, the peripheral edge 4a is the upper end 19 of the ring die.
A part of the material is pulled from the body 2 side toward the center panel 4 by being pulled by a1. In this way, the upper end 19 of the ring die is
a1, and at the same time press surface 19a of the ring die.
Since wrinkles are suppressed by the lower surface 16a of the pressing body, wrinkles do not occur.

When the middle mold 12 continues to descend further, the spring 21 is compressed and the ring die 19 descends, and the peripheral part 6a of the center panel 6 is pressed down by the ring die 19 and the lower surface 16a of the pressing member, as shown in FIG. As in, core die 18
The pressing surface 18a of the core punch 15 starts to come into contact with the wall A, but the line 17 is not compressed, so the relative positional relationship between the pressing body 16 and the core punch 15 does not change.

When the middle die 12 is further lowered, the ring die 19 is also further lowered, and the contact area between the pressing surface 18a and the center panel 4 increases, and the center panel (10) 4 is pressed by the pressing surface 18a, and the body part 2 Although the material is supplied from the side, it is dented into a spherical shape, but since the peripheral portion 6a is pressed down by the pressing body 16 and the ring die 19, radial wrinkles are unlikely to occur at the edge of the central portion 6b.

FIG. 4 shows the central panel 6, which is recessed into a spherical shape, when the middle die 12 is lowered to a position where the lower surface of the ring die 19 contacts the support 20 and the pressing surfaces 18a and 19a form a common spherical part. This shows the state in which a is formed.

When the middle mold 12 is further lowered, as shown in FIG. 5, the spring 17 is compressed and the pressing body 16 moves into the recess 15b, forming the inner wall 10 rising in the axial direction.
A bottom part 7 is formed with a spherically concave central panel 6.

The above-described forming is mainly performed by so-called squeezing, in which the material is drawn from the body 2 side toward the center panel 4 or 6, so there is no risk of forming locally thin parts in the formed bottom 7. .

As shown in FIG. 1, is the center flannel 4 so thin and hard that radial wrinkles still occur in the central iE flannel 6 even when molded by the lower die 13 having one ring die 9?
Alternatively, if the radius of curvature of the center flannel 60 is even smaller, as shown in FIG.
The molding may be performed using a lower die 13 provided with an intermediate ring die 25 capable of forming a common spherical portion. 26 is a spring, and the intermediate ring die 25 and the spring 26
The forming tool shown in FIG. 1 and the forming tool shown in FIG. 6 are similar except that the forming tool shown in FIG.

In this case, in relation to the description of the claims, the pressing body 16 is conceptually divided, and the ring die 19 and the portion 16x of the pressing body 16 opposing this are divided into a pair of pressing bodies, an intermediate ring The die 25 and the portion 16y of the pressing body 16 facing the die 25 will be referred to as another pair of pressing bodies.

In this case, as in the case of Figures 1 and 2, the medium size 12
As shown in FIG. 6 Pushed in until it touches a.

When the middle die 12 continues to descend further, as shown in FIG. be caught. At this time, the material is distributed between the core punch 15 and the mold 22 and the press body 16.
Since it is pulled (so-called squeezed) toward the center/mother flannel 4 side while being pressed (so-called wrinkle press) between the ring die 19 and the ring die 19, wrinkles are less likely to occur.

As the middle mold 12 continues to descend, a spherically concave central panel 16 is formed as shown in FIGS. 9 and 10 in the same manner as in FIGS. 3, 4, and 5. Ru. In this case, the area of the part of the center panel 4 to be pressed by the core die 18 is smaller than in the case of FIG. 3, so (13) Also, radial wrinkles are less likely to occur. When the middle mold 12 continues to descend further, the inner wall portion 10 is formed.

The present invention is not limited to the above embodiments,
If necessary (for example, when the diameter of the center funnel 4 is large), three or more ring dies may be provided. Also 1
The body-formed can 1 may be mainly made of a surface-treated steel plate such as a tin-plated steel plate or aluminum (alloy),
Furthermore, it may be a drawn-and-squeezed molded can.

Furthermore, as shown in FIG.
The can may be a one-piece molded can in which the portion corresponding to the can is formed of an inclined portion extending linearly as shown in FIG. center panel 6
However, 1 without the inclined outer wall 8 is formed directly inside the curved part (see 3' indicated by the dashed line in FIG. 1) which is the ground plane provided at the lower end of the cylindrical body 2. It may also be a body-shaped can. In this case, the bottom and center panels will match.

Further, the shape of the central panel may be spherical, and does not necessarily have to be a part of a complete spherical surface.

(14) (Effects of the Invention) According to the present invention, even if the bottom part is relatively thin and hard, or even if the radius of curvature of the central panel to be further formed is relatively small, the radial The present invention has the effect that a spherically concave central panel can be formed at the bottom of a one-piece can without substantially causing wrinkles.

Therefore, from a relatively thin material, which is advantageous in terms of material cost,
It has the advantage of being able to form a one-piece molded can with improved appearance and buckling resistance.

[Brief explanation of the drawing]

1, 2, 3, 4, and 5 are longitudinal cross-sectional views of essential parts showing the order of forming the center panel in the first embodiment of the present invention, and FIG. 6 and FIG. 7, FIG. 8, FIG. 9, FIG. 10, and FIG. 11 show the second embodiment of the present invention.
FIG. 3 is a vertical cross-sectional view of main parts showing the order of forming the center/mother flannel. 1... Single molded can, 4... Center panel, 4a.
...Peripheral part, 5,7...Bottom part, 6...Central panel,
6a... Peripheral part, 16 (16x e 16 y)
=・Press body, 16a-・-lower surface (periphery becomes press surface), 18...core die, 18a...press surface,
19... Ring die (suppressing body), 19a... Pressing surface, 25... Intermediate ring die (suppressing body (8)

Claims (1)

[Claims] The periphery of the center panel at the bottom of the one-piece molded can is pressed by at least one pair of mutually opposing pressing bodies, each having a pressing surface having a shape corresponding to the periphery of the center panel to be formed. Then, while pressing the peripheral part between the pressing bodies, the inner part of the center panel than the peripheral part is pressed inward by a core die having a spherical pressing surface to form the can. A method for forming the bottom of a one-piece molded can, comprising forming a spherically concave center panel on the bottom.