JPS5933046B2 - Netsuking forming method for metal cans - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming line lining on the body end of a metal can such as aluminum or tinplate as a preliminary step to forming a flange.

This type of conventional netting forming method involves a spin method in which a pair of rolls are pressed against each other by sandwiching the can body end, and a spin method in which the can body end is sandwiched between a center ring and a die ring of a molding die. There is a die method that squeezes the can body in one step, but in the former case, the coating film previously applied to the can body is abraded and peeled off by the rolling contact of the rolls, resulting in a poor enamel rating (standard for determining the quality of the coating film). In addition to causing defects that are easily corroded, the molding equipment is complicated and the molding time is long, which limits mass production and increases costs.

On the other hand, in the case of the latter, the enamel rate value is slightly better than that of the spin method, but since the enamel is squeezed in one instant, wrinkles and spots are likely to occur in the formed necking part, which may cause problems in the flange fern work in the next process. These wrinkles and the seat part cause cracking, which impedes the airtightness of the metal can and leads to leakage.

In particular, the main cause of wrinkles is poor trimming of the can body edge, when there are burrs, debris, etc. attached to the can body edge, when a large amount of spray paint is attached to the can body edge, and when the center ring of the forming die is When the gap between the die rings exceeds the specified value, when the running diameter of the can body end is small, when the temper of the can body end material is high, when the can body end lacks lubrication, deflection due to the thickness of the can body end As a result of experiments, it has become clear that the last factor, the problem of deflection, is the limit for the occurrence of wrinkles.Currently, a large number of cans with deflection on the cane are being produced, and the conventional die method is currently used. This method is currently difficult to adopt, as it inevitably results in a large number of defective products and cannot be molded using tinplate or 3004-H19 hard aluminum.

The present invention provides an effective and suitable forming method that can overcome all the drawbacks of conventional methods in the netting process of metal cans.

Embodiments of the present invention will be described with reference to the drawings.

As shown in Figures 1 to 4, in the first drawing process, the forming die 2 is gradually moved downward from above the can body 1, which is positioned and fixed, and the can body end 3 is inserted into the forming die. 2 and insert it into the circular mouth part 5 of the guide ring 4 installed at the lower end of the can body end 3.
along the inner guide surface 6 of the card ring 4, and at the same time the die ring □ inserted into the guide ring 4.
An adapter 9 is fitted into the inner hole 8 of C so that it can be slid up and down.
The center ring 10, which is attached to the lower end of the can body so as to be able to move slightly and has been moved downward together with the adapter 9, is inserted into the can body end 3 (see FIG. 1), and the center ring 10 is inserted into the can body end 3. Although the intrusion is stopped at a predetermined position, the guide ring 4 and the die ring 7 continue to move downward, and the can body end 3 is moved from the guide surface 6 of the guide ring 4 to the vertical line formed inside the lower end of the die ring 7. The tapered surface 11 with a taper angle α of 200 to 30 relative to the direction is smoothly guided to the drawing surface 11, and the neck portion 12 formed on the can body end 3 is drawn by an amount corresponding to 60% of the final drawing diameter reduction r. 13 (see FIG. 2), and then move the guide ring 4 and die ring 7 down integrally to form a hole in the circumferential gap 14 provided between the center ring 10 and the inner hole 8 of the die ring 7. 20% to 5% of the final height h of the neck portion 12 formed on the can body end 3.
A cylindrical semi-formed neck portion 15 continuous to the shoulder portion 13 is formed by pressing the three edges of the can body end against the lower end of the adapter 9 by an amount within the 0% range (Figs. 3 and 4). 6), the entire forming die 2 is pulled up and moved up to complete the first drawing process, ie, necking forming.

Next, in the second drawing process, the neck part 12 is attached to the can body end 3.
The center ring 16 has an outer diameter that matches the final diameter d, and the height of the circumferential gap 19 formed by the center ring 16 and the inner hole 18 of the die ring 17 during molding is the solution to the final height h. The first drawing operation as shown in FIGS. Through similar sequential operations, the final results are as shown in Figures 5 and 7.
As shown in the figure, a neck portion 12 having a diameter of d and a height of h is drawn continuously to the shoulder portion 21 of the can body 1 to complete the necking process.

In the present invention, draw forming is performed twice under the predetermined tooling conditions and forming conditions as described above, so that the can body end 3, which was a cause of wrinkles in the conventional die method, is not trimmed properly and burrs, debris, etc. are attached. If a large amount of spray paint adheres to the can body end 3, if the running diameter of the can body end 3 is small, if the temper of the can body 1 material is high, the can body end 3 has poor lubricity. Even if there is no wrinkles or uneven thickness on the can body end 3, the necking process can be performed without any wrinkles.

Therefore, it became unnecessary to use a lubricant during molding, or even a small amount of lubricant was sufficient. The molding die molds 2 and 20 adopted in the present invention have a simple structure, are sturdy, easy to maintain and inspect, and have fewer failures, so they have a high molding operation rate and a fast molding speed, so they are suitable for mass production, and are better than the conventional spun method. The cost will be much lower.

In addition, the enamel radar value is much better than that of the conventional spin method or die method.Incidentally, the measurement results of the three corrosion tests are as follows.

The characteristics of the container are evaluated based on the magnitude of the current, and the larger the current, the worse the container characteristics, and the better the container is when the current is zero.

However, various experimental examples and test examples leading to the present invention will be explained below.

Experimental Example 1 The present invention was carried out twice in three cases for a 202 diameter tin DI can (bottomed can) with a can body end plate thickness of 0.180 and painted inner and outer surfaces, with the molding die tool conditions as follows. The results of the netting test by drawing are shown in the table below.

However, α is the taper angle of the die ring aperture surface.

From the test results described above, at an angle α of 100, large and small wrinkles are likely to occur in the molded part. On the other hand, since almost no wrinkles were observed at an angle α of 30, it was found that 30° is more appropriate than 100, which is generally related to the wrinkle formation angle α. Experimental Example 2 A necking test was conducted using the double drawing process of the present invention on a 202 diameter tin Dl can with a can body end plate thickness of 0.18u and painted inner and outer surfaces.The results are shown in the following table.

Note that N-heptane + 0.5% Glamor Wax was used as a lubricant, and the number of test cans was 280 cans for each condition, and the quality was determined by a 100% inspection. In this experiment, since wrinkles were strictly recognized, wrinkles that were ignored in Experimental Example 1 were picked up and counted, but none of them actually led to cracking in the next flanging process. .

From the results of the above experiment, A and B. There is no big difference in any combination of molding conditions in C.

Experimental example 3 The tool conditions of the molding die are as follows, and the can body height is 10.
0.50VII, can body plate thickness 0.265cm, can body inner surface coating amount 199-2107V1 can body outer surface coating amount 145-150
The following table shows the occurrence of wrinkles on mf1 3004-H34 aluminum test cans by two-time necking according to the present invention and one-time necking using the conventional die method.

Sixty test cans each were coated with a lubricant (.1 ethyl alcohol) and tested using a 5500 hyflex press.

However, the criteria for judging are L...the number of wrinkles is 2 or more, M...
...The number of wrinkles is 2 or less to 1, S...The number of wrinkles is 1 (1).

The above test results show that the double necking method of the present invention is far superior to the conventional die method, which is a single necking method, as a countermeasure against wrinkles. It was found that the shapeability of the can is slightly better, but when the buckling strength of the can is taken into account, if the taper angle α of the drawing surface of the die ring is small, the shoulder 21 at the end of the can body is The angle with respect to the vertical direction becomes smaller, which increases the resistance force in the vertical direction in the can during molding.

Therefore, the taper angle of the die ring drawing surface is selected in consideration of the occurrence of wrinkles and the buckling strength of the can.

Furthermore, through the experiments of Experimental Examples 1 to 3, in the present invention, in the first drawing process, the neck part was reduced by 60% of the final drawing diameter and about 20% to 50% of the final height. We have also found empirically that it is optimal to draw the final diameter reduction amount and final length height in the second drawing process.

The reason why this invention obtained good results is that the amount of netting per one time is small, and even if uneven thickness is found at the end of the can body, it will be formed gradually, so there is no direct netting that only causes wrinkles. It is thought that this is no longer a factor.
Thus, the present invention is a groundbreaking method for forming a neck at the end of the can body of this type of metal can.
That is, even under conditions where the end of the can body is somewhat rough due to uneven thickness or various attachments, satisfactory molding can be ensured, and it is suitable for mass production and exhibits excellent effects.

[Brief explanation of drawings]

Figures 1 to 3 are explanatory drawings of the forming operation of the first drawing process of the present invention, and Figures 4 to 5 are forming operations of the first drawing process and the second drawing process of the present invention. FIGS. 6 and 7 are longitudinal sectional views of the end of the can body that has been necked through the forming operations of the first drawing process and the second drawing process of the present invention, respectively. It is. 1... Can body, 2, 20... Molding die mold, 3...
Can body end, 7, 17...Die ring, 8, 18...Inner 1L. 10, 16...Center ring, 11...Aperture surface, 12...Neck part, α...Taper angle, r...
・Final diameter reduction amount, h...Final length height.

Claims (1)

[Claims] 1 When netting a metal can by the cooperative drawing action of the center ring of the molding die and the die ring, the taper angle of the inner drawing surface of the lower end of the die ring is set to 20° to 30°.
The first process is to narrow down the diameter and height of the end of the can body to an intermediate stage, and the second process is to narrow down the diameter and height of the can body to the final stage.
A method for necking metal cans, which prevents the occurrence of wrinkles and buckling as much as possible when plastically forming the end of the can body into a neck portion by performing a second processing.