JPS62101330A - Double seaming method for can body with low axial strength and can shell body used for the method thereof - Google Patents

Abstract

PURPOSE:To easily perform the double seaming of the can body with low axial strength by performing a curling by supporting with pinching the can body on which a cover body is placed and by performing double seaming with ordi nary method thereafter. CONSTITUTION:A cover body 5 is placed on the flange part 2 of a can shell body 1 by a can feeding turret. The canbody is carried onto the turret of a fastening unit, the cover is fit to the chuck 7 located at the upper part with the ascent of a lifter and the upper and lower parts of the can body are pinched by the chuck. The curling part is simultaneously formed with the flange part tip of the cover body 5 being gradually pressed by the peripheral groove of a curling roll 8 with its approaching to the can body side. Thereafter the preseaming by the 1st seaming roll 9 and compact double seaming by the 2nd seaming roll 10 are performed in order same as the conventional double seaming method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a double seaming method for a can body made of a material with low axial strength.

Conventional technology The conventionally well-known double seaming method applied to seaming metal cans, etc. involves placing a lid body with a curled part on a can body having a flange part, and attaching a lifter and a chuck. It consists of a two-step process in which both are supported under pressure between them, preliminary seaming is performed by a first seaming roll, and then final and tight seaming is performed by a second seaming roll. This well-known double seaming method applies a large axial load (commonly called lifter pressure) of 60 to 180 mm to the can body in order to bend the flange part of the can body downward, especially during the pre-sealing process. It will be done. Therefore, if the above double seaming method is applied to the seaming of a can body made of a material with low axial strength, the can body will buckle and the flange will escape in the axial direction of the can body due to excessive seaming. Therefore, it is not possible to secure the desired body hook length. As a result, the third
As shown in Figure (B), the joint surfaces between the body hook 16, seaming wall 19 and cover hook 20 become short, resulting in insufficient seaming strength and when high internal pressure is applied to the can body, the lid body 18 I had a problem with it falling out.

Therefore, for can bodies made of thin plastic materials with low equiaxed strength, the conventional double seaming method described above is not suitable. For example, Japanese Patent Laid-Open No. 58-35028, Japanese Patent Laid-Open No. 35029-1988, and Japanese Patent Laid-Open No. 1983-35029 are methods of seaming such can bodies. 47530
A new double-sealing method has been proposed as described in the publication.

The seaming method described in the above publications uses a special seaming device that employs special rolls such as support rolls and backup rolls, or by providing an annular recess in the can body into which the support roll engages. The axial component force during tightening is received by the rolls to prevent a large axial load from acting on the can body, thereby preventing the 7-rank portion from escaping.

Problems to be Solved by the Invention As mentioned above, in order to seam can bodies with conventionally weak shaft strength, there is an alternative to the conventional double seaming device, which is generally used for seaming metal cans, etc. However, there were problems such as the need for a special seaming device and the fact that the can body had to be made into a special shape.

As a result, problems such as an increase in equipment costs and the need for space to install a dedicated seaming line have arisen.

The present invention was devised in view of the above-mentioned circumstances. To provide a double seaming method that can easily perform seaming on a weak strength can body 21 by simply adding a new front ball (2) using a conventionally well-known double seaming device ft1fi. This is the entire purpose.

Means to solve problems First, the principle of the present invention will be explained with reference to FIG. 2.3.

In double seaming of the can body, the flange portion +4 (FIG. 2) formed on the can body becomes a body hook 6 and a bent portion 17 as shown in FIG. 3 after seaming. In normal tight seaming, for example, in the case of steel cans, the flange length a
The contribution rate to the body hook length b is 75 to 85%. However, if the above-mentioned well-known double-sealing device is used to sew the entire can body with low axial strength, 7.
The rank part escapes due to the buckling of the can body, and the contribution rate of the flange length to the body hook length is 45 to 60%.
It only becomes. As a result, the length of the body hook is insufficient as shown in the 31st section J (b). However, the present inventor conducted an experiment and found that if the flange length is made longer than that of a normal metal can in advance, taking into account all the escape of the 7 rank parts during seaming, it is possible to Even if the flange part escapes, the necessary body hook length bf can be secured,
It has been found that even can bodies with weak shaft strength can be tightly double-sealed.The present invention was made based on the above-mentioned findings.

Incidentally, the lid body is usually formed with a curled portion using a curling machine after the punching process, and then placed on the can body in the seaming process. Therefore, if the flange part is made longer than normal for the above reasons, the working tip of the 7th rank part will hit the tip of the curled part 11 of the lid body, and the flange part will not fit into the curled part, as shown in Fig. 2. occurs. In order to solve this problem, the present invention does not form the curled part after the punching process, but forms the curled part after placing the lid on the can body in the seaming process. Before the process, a method of adding curl 1 ris forming T1 core to perform weak seaming of the can body between the axial strength was adopted.

That is, in the present invention, the can body is formed to be longer than the sum of the length of the entire bent part of the flange of the can body and the length of the body hook, and the can body is completely placed on the can body without being curled, and then the can body is curled with a curling roll. The structure is such that the lid body is curled and then normal double seaming is performed. And, the second invention is an invention of a can body suitable for seaming by the method of the above invention, in which the flange length of the can body' is set to 2.50 to 2.50 to 2.50 to 2.50 to 830 mm for a can body diameter of 42 to 830. 3.30
The configuration is set to mm.

Even if the lid is long, the lid does not have a curl, so the lid can easily attach to the flange of the can body. be healed. The can body whose lid has been rounded is supported under pressure with a lifter and a chuck, and curling is performed, and then double seaming is performed in the usual manner. The flange part escapes slightly toward the can body when tightening, but the flange ≠≠≠==g
'lThe pre-lengthening ensures that the body hook is at the proper length.

Example Embodiments of the present invention will be described below with reference to FIG.

The seaming device for carrying out the double seaming method of the present invention includes a first seaming roll 9 and a second seaming roll 10 arranged around the seaming head of a conventional seaming device. Further, a curling roll 8 for forming a curled portion of the lid is arranged. The curling roll 8 is shown in FIG.
As shown in (2), a circumferential groove corresponding to the shape of the curled portion is formed. Moreover, the can body 1 made of a material with low equiaxial strength is a plastic film to which the seaming method of the present invention is applied, and the flange length a is 2.2 times the body hook length b necessary for tight seaming. 3 to 1.8@. More specifically, it has been found through repeated experiments that when the can body diameter is 42 to 83 m, the necessary body hook length can be secured by setting the flange length to 2.50 to 3.30 m. Therefore, it is desirable to keep it within this range. Furthermore, the 5 pieces of the lid are curled after punching.
! Use what you don't have.

The lid 5 is then tightened to the can body 1 in the following manner.

The lid 5 is placed on the flange portion 2 of the can body 1, which is conveyed by a can conveyor, by means of a can feed turret, using a conventionally well-known method (FIG. 1(a)). At this time, even if the flange 2 of the can body 1 is longer than normal, there will be no tt&f failure because no curled portion is formed on the lid. Then, the can body is carried onto a turret (not shown) of the seaming device, a lifter ascends, the lid is released from the chuck 7 located above, and the can body is clamped between the upper and lower f IJ lids and the chuck.

At the same time as being clamped, the curling roll 8 is brought closer to the can by a cam (not shown), and the tip of the flange portion of the lid 5 is gradually pressed by the circumferential groove of the curling roll 8, forming a curled portion ( Figure 1 1)).

After that, similar to the conventional double seaming method, preliminary seaming is performed by the first seaming roll 9 (see FIG. 1N, the second seaming roll 10
Tight double seams (see Fig. 2) are carried out in sequence. There is a phenomenon in which the flange 2 of the can body escapes in the axial direction of the can body due to the axial load during seaming. However, since the flange is long in advance, the length of the body 7 after seaming can be ensured to be the length necessary to maintain tight seaming.

In the embodiment described above, all the curling rolls for curling or rolling were added to the turret part of the conventional double seaming device, but the present invention is not necessarily limited to this. For example, curling may be performed using a clincher performed before the seaming process, or seaming may be performed using a clincher and a seam. In that case, the conventional seaming device can be used as it is.

It goes without saying that the term "lid" used in the water gate wi=JF includes not only the lid of the can but also the bottom of the Fi in the case of a 3-piece can.

Effects The present invention uses the method described above to wrap a can body with weak spring strength, so even if the flange part of the can body escapes toward the can body side due to the axial load, the flange ≠ ≠ Since it is pre-formed long by that amount, an appropriate body hook length can be secured.

However, since it only requires adding a curling process before the conventional double seaming process, it is easy to use the conventional sand making method and achieve the desired results.

Therefore, there is no need to install a new seaming line using a special frame tightening device.

As described above, the present invention has the advantage of I), which was previously difficult to seam.
Can bodies made of thin flexible material #1, such as E-T cans, can be tightly wound in the d-positive direction, and yet can be tightened using conventional equipment.
Since it can be easily applied and carried out in 7 tB, it has a great practical effect.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the fc main part explaining the double seaming method of the present invention, in which 1) is a view showing a state in which the lid body is placed on the can body, and (b) is a curling process. Diagram showing the state of (
C) is a diagram showing a state in which a preliminary seaming part is formed, B) is a diagram showing a state in which a double seaming part is formed, Fig. 2 is a detailed explanatory diagram of the present invention, and Fig. 3 is a can body. This is a cross-section of a main part for explaining the double seaming state of the seam. 1: Can body 2: Flange part 5: Lid body 7: Chuck
8: Curling roll 9: First tightening roll 10: Second tightening roll 11: Curling part Patent applicant Toyo Seisaku@' Co., Ltd. Applicant agent Patent attorney Katsufumi F (and 2 others)
name) wL l Figure (c) (d) llL2 Figure 3

Claims (1)

[Claims] 1) A can lid body that has not been curled is placed on a can body whose flange length is longer than the sum of the lengths of the bent portion and the body hook, and then curled. A method for improving shaft strength, which is characterized by comprising a step of curling the lid body with rolls, a step of preliminary seaming with a first seaming roll, and a step of tightly seaming with a second seaming roll. Double seaming method for weak can bodies. 2) A can body made of polyethylene terephthalate, a material with low equiaxial strength, in which the length of the seaming flange formed at the open end of the can body is 2.0 mm for a can body diameter of 42 to 83 mm. A can body made of a material with low axial strength, characterized by a thickness of 50 to 3.30 mm.