JPH08168828A - Forming method for di can - Google Patents

Abstract

PURPOSE: To provide the forming method of a DI can, by which wrinkle and crack are not occurred on the profile part of a can bottom part. CONSTITUTION: In the forming method of a DI can, redrawing is performed by making satisfactory one condition or two conditions or over out of the following conditions (1) to (3). (1) The outside diameter d1 of a part positioning on the upper part of the cup 1 of a bland holder sleeve 3 arranged in the cup 1, is made to <=1.004 times through >=1.000 time the inside diameter a of the cup 1, and the outside diameter d2 of a part near the die 2 of the blank holder sleeve 3, is made to <=1.000 time through >=0.990 times the inside diameter A of the cup 1. (2) The R of the shoulder part 5 of the bottom of the blank holder sleeve 3, is made to <=3 times through >=2 times the thickness of an aluminum base stock. (3) A redrawing ratio (A/B) obtained by dividing the inside diameter A of the cup 1 by the inside diameter B of a can-shaped body 6 after redrawing, is made to <=1.40 through >=1.34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method for DI cans in which wrinkles and cracks do not occur in the profile portion (conical portion) of the bottom of the can.

[0002]

2. Description of the Related Art DI cans are Drawing and Ironin
Abbreviation for can formed by g (ironing). Molding of a DI can is performed by drawing a disk 7 formed by punching out an aluminum material into a cup 1 as shown in FIGS. 2A to 2F (FIGS. 2A and 2B). Re-drawing process to the shape body 6 (Fig. 2 c, d), thinning the side wall of the can-like body 6 by ironing process (Fig. 2 e), bottom 8 of the can-like body 6 after the ironing process The step (FIG. 2) of doming is sequentially performed. After the doming process, the can-like body 6 is trimmed, washed, painted, baked, necked in, and flanged out in order, filled with contents, and then shipped with a lid attached. The lid is caulked and attached to the top of the DI can via a rubber packing. For DI cans, JIS-3000 series (Al-Mn) with good drawability is usually used.
JIS-5000 series (A type) alloy with high strength is used for the lid.
(1-Mg-based) alloy is used. The thickness of the aluminum material is about 0.3 mm, but the side wall of the DI can is drawn and ironed to a thin thickness of about 0.14 mm to reduce the material cost. Since the bottom of the DI can is easily deformed, it is relatively thick,
In addition, it is recessed in a dome shape to enhance strength. The material cost of the entire can becomes lower as the diameter of the top of the DI can becomes narrower and the diameter of the lid becomes smaller. As the top diameter of the DI can is reduced, the lower part of the can is also reduced in diameter to maintain stability when stacking the cans vertically. FIG. 3 shows the transition of reducing the diameter of the can end portion. The diameter is decreasing from A bottom, which has a large diameter at the bottom of the can, to C bottom, CVN bottom (triple neck), and CVN bottom (spin neck). When the diameter of the lower portion of the can is reduced, the profile portion (conical portion) 9 becomes longer, and wrinkles are easily generated in this profile portion (FIG. 4). In some cases, cracks may occur.

As a method for eliminating wrinkles and cracks in the profile portion, for example, Japanese Patent Laid-Open No. 3-215646 has been proposed. This method has a yield strength of 25 to 28 Kgf / mm when annealed after rolling.
² is a method in which the material surface roughness Ra is 0.3 to 0.7 μm. However, this method has a drawback that it is against the thinning of the aluminum material by lowering the strength thereof and that the color tone of the can is deteriorated by the surface roughening.

In view of the above, the present inventor has investigated a method for preventing the wrinkles in the profile portion of a DI can from being maintained while maintaining the thinning of the can and without impairing the color tone of the can.
As a result, the wrinkles in the profile part are
We found that it can be prevented by applying a sufficient load to the profile part and work hardening the profile part, and further earnestly researching the redrawing conditions under which the profile part has a sufficient load to complete the present invention. I arrived.
An object of the present invention is to provide a DI having no wrinkles or cracks in the profile portion.
It is an object of the present invention to provide a method for forming a can without reducing the color tone of the can while maintaining the thinness of the can.

[0005]

According to the present invention, there are provided a step of punching an aluminum material into a disk, a step of drawing the disk into a cup, and a step of redrawing the cup into a can.
In a molding method of a DI can, which sequentially performs a step of ironing the side wall of the can-shaped body and a step of doming the bottom of the can-shaped body after the ironing, the redrawing is performed under the following conditions (1) to (3). 1) or two or more of the above conditions are satisfied to perform the molding process of the DI can. (1) The outer diameter d ₁ of the portion of the wrinkle holding sleeve arranged in the cup located above the cup is 1.04 of the inner diameter A of the cup.
Less than 1 time, 1.000 times or more, the outer diameter d ₂ of the wrinkle holding sleeve near the die is less than 1.000 times the inner diameter A of the cup, 0.99
Make it 0 times or more. (2) R of the bottom shoulder portion of the wrinkle holding sleeve is set to 3 times or less and 2 times or more of the thickness t of the aluminum material. (3) The inner diameter A of the cup is divided by the inner diameter B of the can-shaped body after redrawing, and the redrawing ratio (A / B) is set to less than 1.40 and 1.34 or more.

The present invention will be specifically described below with reference to the drawings. 1A to 1C are longitudinal cross-sectional explanatory views showing a mode of redrawing processing in the present invention. FIG. 1A is a diagram showing a state before the start of redrawing. The cup 1 is arranged on the die 2 with the opening facing upward, and the wrinkle holding sleeve 3 is arranged on the bottom surface of the cup 1 and the punch 4 is arranged in the wrinkle holding sleeve 3. The cup 1, the die 2, the wrinkle holding sleeve 3, and the punch 4 are arranged concentrically with their axes aligned. The wrinkle holding sleeve 3 has an upper part having a large diameter (d ₁ ) and a lower part having a small diameter (d ₂ ).
The inner surface is in contact with the upper part, and a slight clearance is opened in the lower part near the die 2. FIG. 1B shows the punch 4
It is explanatory drawing of the method of pushing down into the die 2, and re-drawing the cup 1. The cup 1 is pushed into the die 2 by the punch 4 and redrawn. Meanwhile, the cup 1 is pressed between the die 2 and the wrinkle holding sleeve 3 to prevent the wrinkling. In addition, cup 1
When passing through the bottom shoulder portion 5 of the wrinkle holding sleeve 3, it is bent and bent back to be reduced in diameter. FIG. 1C is a vertical sectional view of the can-shaped body 6 after redrawing. The side wall of the can 6 is thinly drawn.

In the present invention, the redrawing condition (1) is as shown in FIG.
As shown in (a), the outer diameter d ₁ of the portion of the wrinkle holding sleeve 3 arranged in the cup 1 located above the cup 1 is less than 1.004 times, 1.000 times or more the inner diameter A of the cup 1, The outer diameter d _{2 of the} portion close to the die 2 is limited to less than 1.000 times and more than 0.990 times the inner diameter A of the cup. Under this condition (1), the outer diameter d ₁ of the wrinkle holding sleeve 3 is limited to less than 1.004 times or 1.000 times or more the inner diameter A of the cup 1 because the outer diameter d ₁ is 1.004 times or more the inner diameter A. The wrinkle holding sleeve is not inserted into the
This is because if it is less than 0 times, the binding force at the end of the cup does not occur. The reason for limiting the outer diameter d ₂ of the wrinkle holding sleeve 3 to less than 1.000 times and 0.990 times or more of the inner diameter A of the cup 1 is that the outer diameter d ₂ is 1.000 times or more of the inner diameter A, the final stage of the redrawing process. This causes the cup to be restrained and causes cracks, etc. If it is less than 0.990 times, the concentricity between the cup and the die cannot be secured, and the can becomes an uneven can. The position and length (h) of the large-diameter portion (the portion whose outer diameter is d ₁ ) of the wrinkle holding sleeve 3 are the cups after the material has flowed in until the can bottom shape at the time of redrawing is determined from the cup height. It is desirable to correspond to the height. If a desired number of medium diameter portions are provided between the large diameter portion d ₁ and the small diameter portion d ₂ of the wrinkle holding sleeve 3, the wrinkle holding sleeve can be smoothly pushed into the cup. The shape such as the taper angle of the portion where the diameter changes is arbitrary.

In the present invention, the redrawing condition (2) is as shown in FIG.
As shown in (a), R of the bottom shoulder portion 5 of the wrinkle pressing sleeve 3 is limited to 3 times or less and 2 times or more of the thickness (cup thickness) t of the aluminum material. Under this condition (2),
The reason why the R of the bottom shoulder portion 5 of the wrinkle holding sleeve 3 is limited to 3 times or less and 2 times or more of the thickness t of the aluminum material is that when R exceeds 3 times t, the resistance increases due to bending and bending back. This is because it is not expected, and if it is less than 2 times, there is a high possibility that defects such as cracks will occur.

In the present invention, the redrawing condition (3) is as shown in FIG.
As shown in (a) and (c), the redraw ratio (A / B) obtained by dividing the inner diameter A of the cup 1 by the inner diameter B of the can 6 after redrawing is limited to less than 1.40 and 1.34 or more. Under this condition (3),
The reason why the redraw ratio (A / B) is limited to less than 1.40 and 1.34 or more is that when the redraw ratio (A / B) is less than 1.34, the wrinkle suppressing effect is small, and when it exceeds 1.40, problems such as cracking occur. Is.

In the present invention, the redrawing conditions of the conditions (1), (2) and (3) have the same effects even if the respective conditions are individually set and the redrawing is performed. The effect is further improved by setting two or more conditions at the same time. If the surface of the wrinkle holding sleeve that contacts the cup (the surface from the bottom shoulder to the bottom) is roughened, or if a minute groove (cross hatch) is provided on the contact surface,
The load is increased and the profile portion is further hardened to promote the prevention of wrinkles.

[0011]

According to the present invention, at the time of redrawing a DI can, a predetermined load is applied to at least a portion where the profile portion is formed, so that the profile portion is hardened,
Wrinkles and cracks do not occur in the profile section. In the present invention, in order to prevent the wrinkles and cracks in the profile portion of the DI can, the strength of the aluminum material is not weakened and the surface is not roughened, so that the obtained DI can is thin and has a good color tone. Will be things.

[0012]

The present invention will be described below in detail with reference to examples. (Example 1) JIS-3004 with 0.3mm thickness on aluminum material
The alloy H19 material was used to manufacture 10,000 350 ml cans. The shape of the can bottom was a so-called CVN type (spin neck) corresponding to the lid diameter of 204. During redrawing, the outer diameters d ₁ and d ₂ of the wrinkle holding sleeve were variously changed. Cup inner diameter A is
The diameter of the bottom shoulder portion of the wrinkle holding sleeve was 1.8 mm, and the redraw ratio was 1.32. The contact length h between the outer surface of the wrinkle holding sleeve and the inner surface of the cup was set to 20 mm (see FIG. 1). With respect to the obtained DI can, the wrinkle depth of the profile portion, the incidence of cracking, and the punch pressing load were examined. The wrinkle depth is
The surface roughness of the profile portion was measured using a stylus type surface roughness meter, and expressed as the average value of the swing width of the stylus. The results are shown in Table 1.

[0013]

[Table 1]

As is clear from Table 1, the product of the present invention (No.
In Nos. 1 and 2), the profile had no wrinkles and no cracking. This is because the outer diameter d ₁ of the portion of the wrinkle holding sleeve located at the upper portion of the cup is set to 1.000 times or more the inner diameter A of the cup, so that the initial pushing load at which the profile portion is formed becomes high, and This is because the profile portion has hardened. On the other hand, in No. 3 of the comparative example product, since (d ₁ / A) was too small, the load was not sufficiently applied and wrinkles were generated in the profile portion. No. 4 (d ₁ / A) was too large, so the wrinkle holding sleeve could not be inserted. In No. 5, (d ₂ / A) was too small, and axial runout occurred during molding, resulting in uneven thickness.
In No. 6, (d ₂ / A) was too large and the maximum load was applied too much, and the side surface of the can was cracked.

(Embodiment 2) At the time of redrawing, the bottom shoulder portion R of the wrinkle holding sleeve 3 shown in FIG.
The outer diameters d ₁ and d ₂ of the wrinkle holding sleeve are both 87.0 mmφ,
The same procedure as in Example 1 was repeated except that the inner diameter of the cup 1 was 87.3 mm and the redraw ratio was 1.32. With respect to the obtained DI can, the wrinkle depth of the profile portion 9, the crack occurrence rate, and the punch pressing load were examined in the same manner as in Example 1. Table 2 shows the results.

[0016]

[Table 2]

As is clear from Table 2, the product of the present invention (N
In o.7 and 8), the ratio (R / t) of R at the bottom shoulder of the wrinkle holding sleeve to the thickness t (0.3mm) of the aluminum material is 3 times or less and 2 times or more, so wrinkles are formed on the profile part. Did not occur, nor did it crack. On the other hand, No. 9 of the comparative example product had a large (R / t), so that a sufficient load was not applied during the molding of the profile portion and wrinkles occurred. No. 10 is (R /
Since t) was small, the maximum load was applied too much and the side wall of the can-like body was cracked.

(Embodiment 3) At the time of redrawing, the outer diameters d ₁ and d ₂ of the wrinkle holding sleeve 3 shown in FIG.
7.0mmφ, R of the bottom shoulder 5 of the wrinkle holding sleeve 3 is 1.8
mm, and the re-drawing ratio (A / B) between the inner diameter A of the cup 1 and the inner diameter B of the can-shaped body 6 was changed variously. did. With respect to the obtained DI can, the wrinkle depth of the profile portion 9, the incidence of cracking, and the pushing load of the punch 4 were examined by the same method as in Example 1. The results are shown in Table 3.

[0019]

[Table 3]

As is clear from Table 3, N of the product of the present invention
In Nos. 11 and 12, the redraw ratio (A / B) satisfied the conditions of the present invention, so that wrinkles did not occur in the profile portion and cracking did not occur. On the other hand, Comparative Example No. 13 had a large redrawing ratio, so the maximum forming load increased and cracks occurred in the side wall of the can. In No. 14, the redraw ratio was small, so wrinkles were generated in the profile part.

(Example 4) In redrawing, 10,000 at least 350 ml cans were continuously produced by the same method as in Example 1 except that at least two of the three drawing conditions of the present invention were satisfied. . With respect to the obtained DI can, the wrinkle depth of the profile portion, the incidence of cracking, and the punch pressing load were examined in the same manner as in Example 1. The results are shown in Table 4.

[0022]

[Table 4]

As is clear from Table 4, the product of the present invention (No.
15-18), wrinkles do not occur in the profile part,
Moreover, no cracking occurred. Each of the DI cans of the present invention obtained in Examples 1 to 4 had good color tone.

The case of manufacturing a CVN type (spin neck) DI can using the JIS-3004 alloy H19 material as the aluminum material has been described above, but the present invention uses other materials of aluminum material, Also, the same effect can be obtained when applied to the production of other types of DI cans.

[0025]

As described above, according to the present invention, when the DI can is redrawn, the profile portion is hardened by applying a predetermined indenting load, so that the profile portion does not have wrinkles or cracks. Quality DI cans can be produced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a mode of redrawing processing in the present invention.

FIG. 2 is a process drawing of a method of molding a DI can.

FIG. 3 is an explanatory diagram showing a transition of reducing the diameter of the can end portion.

FIG. 4 is a perspective view showing a profile portion of a can end portion.

[Explanation of symbols]

 1-Cup 2-Dice 3-Wrinkle holding sleeve 4-Punch 5-Bottom shoulder 6-Canned body 7-Disc 8-Bottom 9-Profile

Claims (1)

[Claims] 1. A step of punching an aluminum material into a disk,
A step of drawing the disc into a cup, a step of redrawing the cup into a can, a step of ironing the side wall of the can, a doming of the bottom of the can after the ironing In the method of forming a DI can in which the steps are sequentially performed, the redrawing is performed according to one of the following conditions (1) to (3).
A method of molding a DI can, characterized in that one condition or two or more conditions are satisfied. (1) The outer diameter d ₁ of the portion of the wrinkle holding sleeve placed in the cup located above the cup is 1.004 of the inner diameter A of the cup.
Less than 1 time, 1.000 times or more, the outer diameter d ₂ of the wrinkle holding sleeve near the die is less than 1.000 times the inner diameter A of the cup, 0.9
90 times or more. (2) R of the bottom shoulder portion of the wrinkle holding sleeve is set to 3 times or less and 2 times or more of the thickness t of the aluminum material. (3) The inner diameter A of the cup is divided by the inner diameter B of the can-shaped body after redrawing, and the redrawing ratio (A / B) is set to less than 1.40 and 1.34 or more.