JPH08108235A - Menufacture of aluminum alloy di can and device therefor - Google Patents

Abstract

PURPOSE: To provide a manufacture of aluminum alloy DI cans which prevents wrinkles in the necking part or cracks in the flange part from occurring and also to provide a manufacturing device by means of DI working with a high productivity. CONSTITUTION: In the manufacture of aluminum alloy DI cans, the cans are manufactured with necking and flanging workability enhanced by making an ironing ratio per one time at least 40% or more in the ironing work and making the overall ironing ratio 60% or more. Further, one redrawing die 1 and two ironing dies 2, 3 are stored and fixed in a tool box 12, and the ironing ratio by at least one side ironing die is made >=40% to <=50% for manufacturing aluminum alloy DI cans.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum alloy DI can (a can by a squeezing and ironing method) used for beer, juice, carbonated drinks and the like, and an apparatus therefor.
More specifically, the present invention relates to a method of manufacturing a body portion (can body) of a two-piece can having a bottomed cylindrical shape by a DI processing method and an apparatus therefor.

[0002]

2. Description of the Related Art The basic processing technology of the DI processing method is "Light Metal" Vol. 40, No. 3 (1990) P.I.
251 etc., “Aluminum Technical Handbook” (edited by Japan Light Metal Association,
1985) P. 1473 and the like, it will be further described with reference to the drawings. FIG. 2 is a sectional view of a main part of a general DI processing apparatus. Figure 3 D of the molded cup
FIG. 4 is a cross-sectional view showing a deformation process associated with I working, and FIG. 4 is a cross-sectional view of a can body product by the DI working method.

As shown in FIG. 2, usually four dice are generally arranged in tandem. One redrawing die 1 having a circular through hole 1a, three ironing dies 2, 3, 4 arranged coaxially with the redrawing die and having circular through holes 2a, 3a, 4a, A cylindrical punch sleeve 5 fitted inside each of the through-holes 1a to 4a at a predetermined interval and axially movable, and a cylindrical cup fitted to the outside of the punch sleeve 5. And a holder sleeve 6. Spacers are arranged between the dice to keep the distance between the dice constant. Also re-drawing die 1
And ironing dies 2 to 4 have DI for lubrication and cooling.
Coolant is supplied.

In such an apparatus, the bottomed cylindrical cup 7 obtained by the cupping press which is the previous step is used.
(See FIG. 3A) is arranged between the punch sleeve 5 and the redrawing die 1, and the cup holder sleeve 6 and the punch sleeve 5 are advanced in this state. First, the cup holder sleeve 6 presses the bottom surface of the cup 7 against the end surface of the redrawing die 1. Next, the punch sleeve 5 pushes the cup 7 into the through hole 1 a of the redrawing die 1 while pressing the cup 7 with the cup holder sleeve 6. As a result, the cup 8 after the narrow re-drawing of the cup 7
It can be molded into A (see FIG. 3B). After passing through the redrawing die 1, the cup 8A further sequentially passes through the through holes 2a to 4a of the ironing dies 2 to 4 and is gradually ironed to have a predetermined wall thickness by three ironing operations. The can body 8 after the ironing process is formed (see (c) of FIG. 3). The punch sleeve 5 pushes the can body 8 that has undergone ironing further forward, and the bottom portion 8 of the can body 8 is pushed.
a is pressed against the mold 11 for forming the dome portion and the dome portion 9a
Can be molded to manufacture the can body 9 after dome molding (see (d) of FIG. 3). The obtained can body 9 is then subjected to a normal process such as a trimming process → washing / surface treatment / drying process → external coating / baking drying process → internal coating / baking drying process → necking / flanging process → inspection process. After that, the final can body product 10 is obtained (see FIG. 4). By the way, in the above-mentioned three times of ironing, P.P. As described in 1472, etc., it is generally practiced to make the ironing rate in each die average so that excessive ironing is not concentrated in one step. On the other hand, the limit ironing rate per aluminum is set to 40% or less, and if it exceeds this value, it is said that fracture occurs during processing. From these facts, the ironing rate per die of each die is set to a value considerably lower than 40%.

[0005]

Necking in the necking / flanging step, which is the final processing step of can manufacturing, is the necking of the can body necking portion, and the flanging is the subsequent bridging processing. In recent years, the side wall of the can body tends to be thinned for weight reduction, and the necking portion 9b is also thinned. As a result, wrinkling in necking and cracking in flanging can often be a problem. Necking wrinkles cause cracks in flanging. Necking wrinkles and flange cracks may cause improper tightening with the lid, which may cause a problem of leakage of the contents of the beverage can. Particularly in the DI process, as the cross-section reduction rate due to the ironing process increases, the sidewall portion is subjected to a very large work hardening, and the internal stress also remains. If left as it is, necking wrinkles and flange cracks are likely to occur. In a normal production line, internal stress is considerably removed and necking and flanging workability is considerably improved by heating by each drying furnace in the cleaning and painting processes, but it is still insufficient.
An object of the present invention is to provide a method for producing an aluminum alloy DI can, and particularly to a method for producing an aluminum alloy DI can by a DI processing method which is excellent in necking and flanging, particularly a can body thereof. Still another object is to improve the productivity by increasing the rotation speed of DI processing operation.

[0006]

Means for Solving the Problems As a result of earnest research on the generation of necking wrinkles in cans and the prevention of cracks in flanging, the present inventor has recently improved the strength of aluminum alloy sheet materials and improved the performance of lubricants. It is possible to set the ironing rate with one die to 40% or more, and if the ironing rate is increased to increase the internal stress, it becomes a large driving force for removing the internal stress by heating in the drying furnace. The inventors have found that internal stress is removed more than before, and as a result, necking wrinkles and cracks due to flanging are prevented, and the present invention has been reached.

That is, the present invention is characterized in that, in the method for producing an aluminum alloy DI can, the ironing rate of at least one time (one die) in the ironing process is 40% or more, and the total ironing rate is 60% or more. A method of manufacturing an aluminum alloy DI can excellent in necking and flanging workability and an apparatus for manufacturing an aluminum alloy DI can, in which one redrawing die and two ironing dies are stored and fixed in a tool box. An apparatus for producing an aluminum alloy DI can, wherein at least one of the ironing dies has an ironing rate of 40% or more.

Hereinafter, the present invention will be described in detail. The present invention is characterized by the ironing ratio by the die when manufacturing the aluminum alloy DI can, and the redrawing die, the arrangement of the ironing die, and the like may be the same as the conventional one.
In this case, as shown in FIG. 2, when re-drawing dies 1 and ironing dies 2, 3 and 4 are used, the ironing rate of at least one of the three ironing dies is 40% or more, preferably in the embodiment. As shown, it must be 42% or more. If the ironing rate is too high, there is a risk of breakage, so the upper limit is preferably around 50%. The ironing rate is represented by the wall thickness reduction rate. If the wall thickness before ironing is a and the wall thickness after ironing is b, then (ab) / a × 10
It is represented by 0 (%). However, the ironing rate of the first ironing was defined as the rate of decrease in wall thickness after the first ironing with respect to the thickness of the base plate.
Generally, the wall thickness of the side wall portion below the necking portion of the can body after ironing is usually made slightly thinner than the thickness of the necking portions 8b and 9b as shown in 8c and 9c of FIG. In the present invention, the ironing rate is defined by the average thickness of the side wall portions (8c and 9c in FIG. 3) of the can body. The total ironing rate is (a−c) / a × 100 (%), where a is the thickness of the base plate and c is the final thickness after ironing.

In the present invention, since the ironing rate by at least one die is 40% or more, the ironing rate by the remaining dies can be made smaller than before, and as a result, the number of ironing dies can be reduced. . This state is shown in FIG. As shown in the drawing, there are two ironing dies, and at least one of them is configured to have an ironing rate of 40% or more. Then, two ironing dies and one redrawing die are housed and fixed in the tool box 12. In the present invention, the ironing rate of only one die is 40
If it is more than%, there is no limit to the choice of dice,
Desirably, the ironing rate of the last die, that is, the die of 3 in FIG. 1 and the die of 4 in FIG. 2 is 40% or more. The reason is to maximize the internal stress as described later.

The overall ironing rate after the final die ironing is 60% or more in the present invention as in the prior art. The upper limit is determined by the strength of the plate, the DI processing technology, the thickness of the redraw can, the use of the can, etc., and is generally 7
It is about 0%. The aluminum alloy used in the present invention may be a general aluminum alloy such as 1000 series, 3000 series, 5000 series, but is usually 3004, 3104.
A 3000 series alloy is used. As the lubricating oil, emulsion type and solution type water-soluble lubricating oils, general mineral oils, synthetic oils and the like are used.

[0011]

Function: The internal stress generated by DI processing is considerably removed by heating in each drying furnace in the cleaning and painting processes, but the conventional one is not sufficient. The residual internal stress causes wrinkles and cracks in the necking and flanging process. In particular, this problem is becoming more serious due to the recent trend of thinning. The main driving force when the internal stress is removed is the magnitude of the internal stress and the heating temperature. The driving force is determined by the magnitude of internal stress if the heating conditions in the cleaning and painting processes are constant. The removal of internal stress is a so-called recovery phenomenon, but it is necessary to increase the internal stress by cleaning the can body and heating in a drying furnace in the coating process (usually 150 ° C to 250 ° C) to increase the driving force for removal. However, the residual stress after heating becomes small.

According to the present invention, in order to increase the internal stress before heating based on this phenomenon, the ironing rate by one die is increased. It is preferable to use a die with a high ironing rate as the final die for ironing, because a large internal stress generated at a high ironing rate in the middle causes a recovery phenomenon due to the heat generated in the subsequent ironing process, and the internal stress decreases. This is to avoid this, as it may occur. Further, if the ironing rate of the last ironing die is lowered, defective appearance is likely to occur.

A specific description will be given below with reference to examples.

【Example】

[Example 1] Example in which three ironing dies were used. A cup was formed by a usual method using an aluminum alloy plate JISA3004-H19 and a plate thickness of 0.30 mm. And a can body for 350 ml was produced by the processing method according to the present invention. The wall thickness of the side wall portion 8c of the can body after the final ironing is 0.11 mm.
And Therefore, the total ironing rate is 63% ((0.30-
It becomes 0.11) /0.30). The necking portion 8b has a constant plate thickness of 0.168 mm in order to evaluate the workability. This can body is trimmed, washed, painted, 200 ℃ ×
After 20 minutes of baking treatment, four stages of die necking were performed to obtain a test sample for evaluating flange formability. As a test method of the flange forming method, a frustoconical tool having an apex angle of 75 ° was pushed into the opening end of the necked can body, and the amount of expansion in the radial direction when the opening end was broken was measured. Table 1 shows the results. In the table, No. 1 to 4 are DI processing methods according to the method of the present invention, in which the overall ironing rate is the same, and the final ironing rate by the ironing die is 40.
% And above. No. 5 and 6 are DI processing methods according to the conventional method, and the ironing ratio of each die is less than 40%. It is understood that the method of the present invention is superior to the conventional method in the radial expansion amount of the opening end, that is, the flange formability.
According to the method of the present invention, necking wrinkles did not occur.

[0014]

[Table 1]

[Example 2] Example in which two ironing dies were used A can body was produced in the same manner as in Example 1 except that the ironing process was performed by the apparatus shown in Fig. 1, and the workability was evaluated. The results are shown in Table 2. In the table, No. 1, 2, and 3 are DI processing methods according to the present invention, in which the ironing process is performed twice and the ironing rate of the second ironing process is set to 40% or more. No. 4,5
Is a DI processing method by a conventional method, and the ironing rate is less than 40% for each of the three ironing steps. And the total ironing rate was adjusted to be the same. According to the method of the present invention, it can be seen that the radial expansion amount of the opening end portion, that is, the flange formability is superior to the conventional one. Further, according to the method of the present invention, necking wrinkles did not occur.

[0016]

[Table 2]

[0017]

EFFECTS OF THE INVENTION According to the method of the present invention, the squeezing rate in at least one squeezing process in DI processing is 40%.
% And the total ironing rate is 60% or more, a can body for a two-piece can having excellent workability without necking wrinkles or flange cracks can be obtained. In addition, it is economical because the number of dies can be reduced as compared with the conventional one. Since the toolbox can be made smaller by the number of dice,
The stroke length of the processing device can be shortened. As a result, it is possible to increase the number of rotations of the processing device with high accuracy, so that productivity is also improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a DI processing apparatus showing an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a general DI processing apparatus.

FIG. 3 is a cross-sectional view showing a deformation process associated with DI processing of the molded cup (7-7).

FIG. 4 is a sectional view of a can body product obtained by DI processing.

[Explanation of symbols]

 1 Redrawing Die 1a Through Hole 2 Ironing Die 2a Through Hole 3 Ironing Die 3a Through Hole 4 Ironing Die 4a Through Hole 5 Punch Sleeve 6 Cup Holder Sleeve 7 Cup 8A Cup after Redrawing 8 Can Body 8a After Ironing Bottom 8b Necking part 8c Side wall part 9 Can body after dome forming 9a Dome part 9b Necking part 9c Side wall part 10 Can body product 11 Dome forming die 12 Tool box

Claims (6)

[Claims] 1. A method of manufacturing an aluminum alloy DI can, wherein an ironing rate of at least once in ironing is 4
A method for producing an aluminum alloy DI can excellent in necking and flanging workability, characterized in that the ironing rate is 0% or more and the total ironing rate is 60% or more. 2. The method for producing an aluminum alloy DI can according to claim 1, wherein the ironing rate at least once is 40% or more and 50% or less. 3. The method for producing an aluminum alloy DI can according to claim 1, wherein the ironing ratio by the last ironing die in a plurality of ironing processes is 40% or more. 4. The method for producing an aluminum alloy DI can according to claim 1, wherein the number of ironing dies is two, and the ironing rate by at least one of the dies is 40% or more. 5. An apparatus for producing an aluminum alloy DI can, wherein one redrawing die and two ironing dies are housed and fixed in a tool box, and at least one of the ironing dies has an ironing rate of 40. % Aluminum alloy DI can manufacturing equipment. 6. The ironing rate of the last ironing die is 40%.
The above is the apparatus for manufacturing an aluminum alloy DI can according to claim 5.