JPH0833933A - Manufacture of thin-walled di can - Google Patents

Abstract

PURPOSE:To provide a manufacturing method of a container where the sheet thickness of a DI can is reduced without deteriorating the pressure strength, and the weight is reduced. CONSTITUTION:The bending equivalent to the precision that the bending radius is >=1/2 of the thickness of the stock up to the diameter of the can is achieved to the can bottom before the ironing process in manufacturing a DI can, and the unbending and setting is achieved by the doming which is the final process. This constitution reduces the sheet thickness of the DI can without deteriorating the pressure strength, and contributes to the resource saving of the container.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to DI cans (Draw &
The present invention relates to a method for manufacturing a squeezed and ironed can called an ironed can.

[0002]

2. Description of the Related Art A method of manufacturing a DI can is as follows.
And a redrawing (hereinafter referred to as a second drawing) to form a cylindrical cup having a drawing ratio of about 2, and subsequently, several side walls of the cup are installed in series with the punch without changing the diameter of the cup. A method of making a can by squeezing the wall thickness to make a can high by squeezing between the dies is described, for example, as described in Journal of Japan Society of Mechanical Engineers, Vol. 84, No. 748, pages 256-260. It is already well known, and various innovations have been made with USP 12813 as a basic patent. For example, JP-A-3-27828,
In JP-A-3-71938, the formation of wrinkles during molding is prevented and the pressure resistance is improved by devising the shape of the can bottom.

[0003]

In the case of a DI can, the side wall of the can is squeezed and thinned, but the bottom of the can is slightly overhanged (the thickness reduction of the part corresponding to the can bottom is 3% or less). The thickness of the original plate remains almost as it is. At present, the plate thickness is about 0.08 mm at the side wall, but 0.22 mm at the bottom of the can.
It is 0.25 mm. Even if the thickness of the DI can is reduced in order to reduce the weight of the DI can, the thickness of the side wall has reached the limit where it cannot be further reduced. Therefore, it suffices to reduce the thickness of the can bottom portion, but if the thickness of the original plate is reduced, the pressure resistance of the can bottom will be insufficient, and the function as a can will not be obtained sufficiently. In Japanese Patent Laid-Open No. 3-71938, it is possible to improve the pressure resistance by devising the shape of the can bottom, but this is not a technology that satisfies the weight reduction of DI cans. The present invention solves this problem and provides a manufacturing method that satisfies the contradictory characteristics of reducing the weight of a DI can (reducing the thickness of the bottom of the can) and improving the pressure resistance.

[0004]

The present invention has been made to solve the above problems, and the gist thereof is D
Before the ironing process in the production of I-cans, the can bottom is bent at a bending radius equal to or more than half the thickness of the material and equal to or less than the diameter of the can. Thin-walled D characterized by being bent back
It is in the method of manufacturing I cans.

A feature of the present invention is that the portion corresponding to the bottom of the DI can is subjected to bending and bending back with almost no reduction in plate thickness (provided that the reduction in plate thickness is less than about 3%) to perform work hardening. . This bending may be performed before the doming process, but considering the current normal line configuration, the line configuration is changed at the same time as the first drawing and / or after the first drawing and before the second drawing. Is less desirable,
Further, it is desirable that the bending back process is performed in the second drawing process and / or the ironing process to obtain a normal can bottom shape. Also, the number of times of bending and bending back processing may be once,
You may go in two times. As the shape of bending,
For example, the bottom portion of the first squeezing cup may have a bent shape as shown in FIG. The bending amount is set so that the bending radius is equal to or more than ½ of the material plate thickness and equal to or less than the diameter of the can. If the bending radius exceeds twice the can diameter,
Since the amount of work hardening is small and the effect of increasing the pressure resistance of the can is small, the bending amount whose bending radius corresponds to the diameter of the can is set as the lower limit. Further, when the bending radius is less than ½ of the material plate thickness, it is easy to break during bending, so the bending amount corresponding to ½ of the material plate thickness is set as the upper limit. The shape of the processed portion may be an arc shape as shown in FIG. 2 or any other shape.

The chemical composition of the raw material may be any of steel, aluminum, etc., as long as it is usually used for DI cans. Since the compressive strength is proportional to the yield stress of the material after forming, it is desirable to increase the sum of the yield strength and the work hardening amount of the material in order to secure the compressive strength. On the other hand, in order to secure the formability of drawing, it is desirable to reduce the C content when the material is steel. Therefore, Ti and N are made extremely low C
In addition to containing one or more of b and B,
Increase the yield strength and ductility by increasing Mn, etc.
It is also possible to further reduce the weight by increasing the processing amount of the portion corresponding to the can bottom.

As a material to which the manufacturing method of the present invention can be applied, a material for a normal DI can as described above may be used. For example, a tin-plated metal strip, a chrome-plated metal strip, or a chromium-plated upper layer of the tin-plated layer. Plated metal band, one with a chromium oxide film formed on top of it, metal band (with or without plating) coated on both sides or with one side of resin (as metal band Is also applicable to the above-mentioned plated metal strip, and the metal strip may be made of steel (usually steel used for containers, such as aluminum-killed steel, IF steel, etc.), aluminum (usually Any aluminum can be used for the container,
For example, there are 3000 series, 5000 series aluminum alloys, etc.),
Etc. are applicable.

[0008]

[Example] The steel for cans shown in Table 1 was manufactured by a conventional method. The temper degree is T4-CA. Using each can steel in Table 1,
I made a can.

A disk having a diameter of 140 mm was punched out, and simultaneously with punching, drawing and bending were performed. The diameter of the first throttle cup is 87 mm, and the bending radius of the cup bottom is 0.1 mm to
It was processed by variously changing it to 70 mm. As a comparative example, a can which was not subjected to the bending process within the scope of the present invention was also molded. Subsequently, the final product was obtained by re-drawing with a diameter of 66 mm, ironing and doming.

Formed cans are processed according to the actual can making process.
Paint baking was performed at 05 ° C for 10 minutes to obtain a finished product. Using this can, pressure resistance was measured. The compressive strength was defined as the compressive strength when the internal pressure was applied to the can and the can bottom started buckling. Table 2 shows examples of the present invention and comparative examples.

Embodiment 1 in which bending is not performed after the first drawing
Nos. 4 and 18 cannot be made lighter, and Example 15 has insufficient pressure resistance. Further, Example 1 in which the bending amount is outside the range of the present invention
6 and 17 are the desired D due to breakage during processing or lack of compressive strength
I can't get it. On the other hand, in each of Examples 1 to 13, which is the method of the present invention, it is understood that the pressure resistance is high and the weight reduction is sufficiently achieved.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

As described above, the thickness of the DI can (in particular, the thickness of the bottom of the can) can be reduced without impairing the pressure resistance, which contributes to resource saving of the container.

[Brief description of drawings]

FIG. 1A is a diagram showing an example of a cross section of a cup after drawing in the first stage of a DI can manufacturing process according to the method of the present invention. (B)
FIG. 4 is a view showing a cross section of a cup after drawing in the first stage of a DI can manufacturing process by a comparative conventional method.

2 (a) and 2 (b) are schematic views showing an example of a cross section of a can bottom portion after bending according to the method of the present invention.

Claims (1)

[Claims] 1. When manufacturing a DI can, before the ironing process, a bending process is applied to the bottom of the can so that the bending radius is not less than ½ of the material plate thickness and not more than the can diameter. The method for producing a thin-walled DI can, which is characterized in that the bending back process is performed by the doming process.