JPH0747182B2 - Neck-in adhesive can barrel manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a neck-in adhesive can body having a side-by-side overlapping adhesive portion, which is used for canning coffee cans, oolong tea cans, etc. The present invention relates to a method for forming a neck-in portion on a bonded can body.

(Prior Art) Recently, a can body having a neck-in part is widely adopted as a can body of a can, especially a beverage can. However, in order to reduce the area of the lid part and reduce the material cost, the neck-in part is required. The larger the amount of shrinkage is, the more preferable.

However, in the case of an adhesive can body having a side-by-side overlapped adhesive part, vertical wrinkles are likely to occur during necking processing, and a neck with a larger diameter reduction amount than a draw-ironing formed can (so-called DI can) or a welded can body. It was difficult to form the in part.

For example, it is possible to form a neck-in part with a nominal diameter of 206 in the case of DI cans and welded can bodies in cans with a nominal diameter of 211 (inner diameter of 63.34 mm for bonded can bodies), which is the mainstream in beverage cans today. However, in the case of an adhesive can body, it is usually 209
The diameter (inner diameter 62.55 mm) or the nominal 208.5 diameter (inner diameter 61.60 mm) was the limit of neck-in formation. Therefore, in the case of the adhesive can body, there is a problem that it is difficult to reduce the material cost of the lid portion as compared with other types of can bodies.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for manufacturing a neck-in bonded can body having a neck-in portion, in which the diameter reduction amount is as large as in the case of a DI can or a welded can body. And

(Means for Solving the Problems) A method for manufacturing a neck-in bonded can body having a side-by-side overlapped adhesive part of the present invention is a step described below of an outer joint edge of an end that becomes a neck-in part of the adhesive can body. For forming a right cylindrical cylinder having a notch or a hole in a portion to be a portion, a pre-neck having a step portion and a slightly rising projecting edge portion by pre-necking the end portion A step of forming a portion, a first necking step of necking the end portion where the pre-neck portion is formed to form a short cylindrical portion, and a second necking step of necking the short cylindrical portion, The drawing ratio in the necking step of is higher than the drawing ratio in the second necking step.

(Operation) First, a pre-necking step of forming a pre-neck portion having a step portion and a projecting edge portion that slightly rises is performed. However, the step of the outer joint edge of the adhering portion of the straight cylindrical adhesive can body used as the material is performed. A cutout portion or a hole portion is formed in a portion that should be a portion, and this portion locally becomes a single plate and has a relatively small deformation resistance. Moreover, the rising edge of the projecting edge is also small.

Therefore, by performing the necking process with a relatively large drawing ratio, the pre-neck portion can be formed in the same shape as the portion of the adhesive portion other than the adhesive portion and without generating vertical wrinkles.

Next, in the first necking step, the end portion where the pre-neck portion is formed is necked to form a short cylindrical portion having a reduced diameter. The pre-neck portion has a shape substantially similar to the inner surface of the necking die. And, because it is easy to fit in with the inner surface and the rigidity due to the slightly raised ridge,
Even if necking is performed with a drawing ratio slightly larger than the drawing ratio when forming the pre-neck portion, wrinkles are less likely to occur in the short cylindrical portion.

In the second necking step, the short cylindrical portion is necked. However, since the drawing ratio in this case is smaller than that in the first necking step, wrinkles are less likely to occur.
Therefore, it is possible to manufacture a neck-in bonded can body having a relatively large drawing ratio as a whole, that is, a diameter reduction amount similar to that of a DI can or a welded can body.

Since the notch or the hole is formed not on the inner joint edge but on the outer joint edge, there is no possibility that the end surface where the metal is exposed is corroded by the content liquid and contaminates the content liquid.

(Example) In FIG. 1, reference numeral 1 denotes an adhesive can body before forming a neck-in portion, which is a right cylinder and has an outer joint edge 3 at an end 1a of the adhesive can body 1 which is a neck-in portion. And inner joint edge 9
And an adhesive layer 2 formed by adhering and via an adhesive layer 5.
On the outer joint edge 3 (see FIG. 10), a trapezoidal notch 4 elongated in the axial direction is formed.

The notch 4 is formed in a portion 3a of the outer joint edge 3 that is to be a step 6 (FIG. 2) formed in a pre-neck portion forming step described later, and preferably has a half of the axial length of the portion 3a. that's all,
More preferably, it is formed so as to cover 2/3 or more. The notch 4 is slightly below the portion 3a (about 1-2 mm)
It may protrude.

Normally, the upper end 4a of the cutout portion 4 is located about ₁ to 2 mm below the upper end surface 1a ₁ of the adhesive can body 1, and the lower end 4b is about 3 to 5 mm from the upper end 4a.
Located below. The width W of the adhesive portion 2 is usually about 5 mm in order to secure the necessary adhesive strength, but the width of the notch portion 4 is the width W.
2/5, that is, about 2 mm is desirable.

Such a bonding can body 1 has a notch 4 formed at a portion which is to be an outer joint edge of a rectangular metal blank (not shown) before forming a superposed portion for bonding,
It is formed by a conventional method for manufacturing a bonded can body.

Next, the end portion 1a of the adhesive can body 1 is pre-necked,
As shown in FIG. 2, a pre-neck portion 8 having a step portion 6 and a projecting edge portion 7 (height is usually about 1 to 2 mm) that stands slightly above the upper end of the step portion 6 and extends in the axial direction is formed. The pre-neck portion 8 is formed with a large reduction ratio R ₁ within the range where vertical wrinkles do not appear during formation. Here, the reduction ratio R ₁ is, assuming that the outer diameter of the body of the adhesive can is D ₁ and the outer diameter of the projecting edge portion 7 is D ₂ , become. The drawing ratio R ₁ is usually about 5 to 6%.

Reference numeral 10 in FIG. 3 shows an example of a tool for forming the pre-neck portion 8. Reference numeral 11 is a guide body, 12 is a pre-necking die, and 13 is a center core movable in the radial direction (Japanese Patent Publication No. 50-41).
Reference numeral 92), 14 is a fixed holder for holding the center core 13. The inner surface 12a of the pre-necking die 12 has a first curvature portion 12a ₁ having a relatively large cross-section curvature radius from the inlet side,
A straight line section 12a ₂ extending obliquely inward, a second curvature section 12a ₃ having a relatively small radius of curvature, and a rising section extending in the axial direction.
It consists of 12a ₄ . The level of the lower surface 14a of the holding body 14 is
The height of the rising portion 12a ₄ has determined to be equal to the height substantially the flange portion 7 of the Purenekku portion.

When the end portion 1a of the adhesive can body 1 is loaded into the tool 10 described above, not only the adhesive portion 2 but also the adhesive portion 2 (since the notch 4 reduces the deformation resistance), the inner surface 12a of the die is A step portion 6 having a uniform cross-sectional shape along the entire circumference and a pre-neck portion 8 having a projecting edge portion 7 without vertical wrinkles is formed with a relatively large drawing ratio R ₁ while being closely contacted along the circumference and being reduced in diameter. be able to.

When the notch 4 is formed, even if the tool 10 that forms the satisfactory pre-neck portion 8 as described above is used, if the notch 4 is not formed, the end 2a of the adhesive portion and the end 2a thereof are not formed. The vicinity cannot be in close contact with the inner surface 12a of the die and becomes almost flat as shown by the chain line 2a (probably due to a kind of buckling phenomenon to the inner surface side), and the subsequent necking process. Cannot be carried out satisfactorily.

In the first necking step, the end portion 1a having the pre-neck portion 8 formed therein is necked at a reduction ratio R ₂ larger than the reduction ratio R _1, and as shown in FIG. Forming 16. This necking process, as shown in FIG.
Although this is performed using a normal necking tool 17 for a bonded can body, since the pre-neck portion 8 is formed at the end 1a,
Since the end portion 1a and the inner surface 18a of the necking die 18 are well fitted to each other, vertical wrinkles do not occur in the short cylindrical portion 15 even if the drawing ratio R ₂ is relatively large. Here, the reduction ratio R ₂ is 15
If the outer diameter of is D ₃ , Becomes The drawing ratio R ₂ is preferably 6 to 9%. R ₂
Is less than 6%, the end portion 1a, particularly the end portion 2a of the adhesive portion, cannot sufficiently follow the inner surface 18a of the necking tie, so that the shoulder portion 16 having a satisfactory shape cannot be formed. This is because if it is larger than 9%, vertical wrinkles are likely to occur in the short cylindrical portion 15.

In the second necking process, the short cylindrical portion 15 is necked at a drawing ratio R ₃ smaller than the drawing ratio R ₂ by a necking process (not shown) having the same structure as the necking tool 17 except that the dimensions are different. As shown in Fig. 6, the shoulder
20 and the short cylindrical portion 21 are formed to manufacture a neck-in bonded can body 23 having a two-stage neck-in portion 22. The aperture ratio R ₃ is
If the outer diameter of the short cylindrical portion 21 is D ₄ , Becomes

The reason for making the drawing ratio R ₃ smaller than the drawing ratio R ₂ is as follows. In other words the first necking step, the vicinity of the adhesive portion is in the state easy out wrinkles or small wrinkles (to the extent that no problem as a container) is generated, drawing rate R ₃ a drawing rate R ₂ This is because wrinkles develop in the short cylindrical portion 21, and defects such as cracks during subsequent flange processing, winding failure, spoiling aesthetics and losing the container function are likely to occur. Usually, the drawing ratio R ₃ is preferably 3.5 to 5%.

The present invention is not limited to the above embodiments,
For example, after the first necking step (FIG. 4) of forming the short cylindrical portion 15, a reforming step for reducing the inclination angle θ of the shoulder 16 may be added. By the reforming, the shoulder portion 16 is transformed into the shoulder portion 25 shown in FIG. 7 in which the slope angle δ is smaller than the slope angle θ. Also in this case, the short cylindrical portion 15
By necking in the same manner as in FIG. 6, the neck-in bonded can body 28 having the two-step neck-in portion 26 shown in FIG. 8 can be manufactured.

The neck-in adhesive can body 28 has a relatively large radial width and has a relatively small inclination angle δ of the shoulder portion 25, so that it is buckled by an axial load applied during flange formation of the opening, winding of the lid, and the like. It has the advantage of being difficult.

Further, the notch 4 may have any suitable shape, for example, as shown in FIGS. 9 (a), (b), and (c), it may have a rectangular shape, an arc shape, a triangular shape, or the like. Good. Further, instead of the notch 4, as shown in FIGS. 9 (d) and 9 (e), a hole having an appropriate shape such as a rectangular shape or an elliptical shape.
30 may be formed.

Next, a specific example will be described.

Nominal 211 diameter (outer diameter D ₁ is 65.
80 mm) and a height of 125.40 mm of an adhesive can body 1 were produced. The width W of the adhesive part 2 is 5 mm, the notch 4 is trapezoidal, and the width (height of trapezoid)
Is 2.0mm, the distance between the top face 1a ₁ and the top 4a is 2.0mm, the top 4a
And the lower end 4b, that is, the length of the base of the trapezoid was 2.7 mm, and the length of the top of the trapezoid was 1.7 mm.

Next, the end 1a of the adhesive can body 1 is loaded into the pre-neck forming tool 10 (Fig. 3), and the height is 1 mm and the outer diameter D ₂ is 62.01 mm (nominal).
A pre-neck portion 8 having a projecting edge portion 7 having a diameter of 208.5) was formed. The first curvature portion 12a ₁ of the inner surface 12a of the pre-necking die 12
Has a radius of curvature of 5 mm, the linear portion 12a _{2 has} an inclination angle α of 37.5 degrees, and the center core 13 has a diameter of 61.55 mm.

The draw ratio R _{1 in} this case was 5.8%.

Then, by using necking dies 17 (FIG. 5), as shown in FIG. 4, it is 12mm height, the outer diameter D ₃ 60.32mm (nominally 20
A short cylindrical portion 15 having a diameter of 7.5) and a shoulder portion 16 were formed. In this case, the reduction ratio R ₂ was 8.3%.

After that, the short cylindrical part 15 has a height of 6.25 mm and an outer diameter D ₄ of 57.71 mm.
A neck-in-bonded can barrel 23 having a two-stage neck-in portion 22 was formed by forming a short cylindrical portion 21 (nominal 206 diameter) and a shoulder portion 20 (drawing ratio R ₃ is 4.3%). In each of the above neck-in processes, each shoulder 1 without vertical wrinkles
The shapes of 6,20 were also satisfactory.

Next, a flange portion was formed on the short cylindrical portion 21 (not shown), and the lid portion was double-wound. Also, the bottom of the adhesive can body 1 is nominally 209
A neck-in portion having a diameter was formed, and the bottom portion was double-wound to produce a sealed can (not shown). In this case, since the outer diameter of the double winding fastening portion (not shown) on the lid portion side is smaller than the inner diameter of the double winding fastening portion on the bottom portion, the cans can be stacked on each other.

For comparison, a bonded can body 1 having a notch 4 (nominal 21
1 diameter) was directly inserted into the necking tool 17 (Fig. 5) without going through a pre-necking process to form a short cylindrical portion 15 with a nominal diameter of 207.5. Wrinkles occurred and a satisfactory neck-in can body could not be obtained.

(Effect of the Invention) According to the present invention, it is possible to manufacture a neck-in bonded can body having a neck-in portion whose diameter reduction amount is as large as that of a DI can or a welded can body.

Therefore, the present invention has the advantages that the material cost of the lid is reduced and that a sealed neck-in adhesive can barrel can be manufactured that can be stacked on top of each other.

Further, it has an advantage that the flat portion of the can body, that is, the printing screen can be made larger than the three-stage neck or the four-stage neck adopted in the DI can and the welded can.

[Brief description of drawings]

FIG. 1 is a front view of an essential part of an example of an adhesive can body before necking used for carrying out the present invention, and FIG. 2 is an essential part showing a state after a pre-neck part is formed on the adhesive can body of FIG. Front view,
FIG. 3 shows a tool for forming a pre-neck portion,
FIG. 4 is a longitudinal sectional view of an essential part showing a state in which a pre-neck part is formed in the adhesive part, and FIG. 4 is a front view of the essential part showing a state after the first necking step is applied to the adhesive can body of FIG. The figure is a longitudinal cross-sectional view of a main part showing a state in which a short cylindrical portion is formed in the adhesive portion using the tool for the first necking step, and FIG. 6 shows the second necking step in the adhesive can body of FIG. The first obtained
7 is a front view of a main part of a neck-in adhesive can body which is an example of FIG. 7, FIG. 7 is a front view of a main part showing a state after the adhesive can body of FIG. 4 is reformed, and FIG. A second example of the necking step, which is a second example of the neck-in adhesive can body, showing a front view of a main part, FIGS. 9 (a), (b), (c) and FIG. 9 (d). ) And (e) are front views of main parts showing various examples of the shapes of the notch and the hole, respectively, and FIG. 10 is a transverse sectional view taken along line XX of FIG. 9 (a). DESCRIPTION OF SYMBOLS 1 ... Straight cylindrical adhesive can body, 1a ... End part which becomes a neck-in part, 2 ... Adhesive part, 3 ... Outer joining edge, 4 ... Notch part, 5 ...
Adhesive layer, 6 ... Step portion, 7 ... Projection edge portion, 8 ... Pre-neck portion,
15 ... Short cylinder part, 22 ... (2 steps) neck-in part, 23 ... Neck-in adhesive can body, 26 ... (2 steps) neck-in part, 28 ... Neck-in adhesive can body, 30 ... hole.

Claims (1)

[Claims] 1. A method of manufacturing a neck-in bonded can body having a side-by-side bonded portion, wherein the manufacturing method comprises a step portion described later on an outer joint edge of an end which becomes a neck-in portion of the bonded can body. A step of forming a straight cylindrical adhesive can body in which a notch or a hole is formed in a portion to be formed, pre-necking the end, and forming a pre-neck part having a step and a slightly rising projecting edge. A first necking step, which includes a forming step, a first necking step of necking the end portion having the pre-neck portion to form a short cylindrical portion, and a second necking step of necking the short cylindrical portion. A method for manufacturing a neck-in bonded can body, wherein the drawing ratio in the step is larger than the drawing ratio in the second necking step.