JPH0451972A - Can cover seaming method - Google Patents

Abstract

PURPOSE:To obtain the pressure closed container having an excellent sealing-up performance which is free from deformation, and also, generates no air leakage extending over a long period by executing seaming, while holding pressure in a can higher than pressure of the outside of the can. CONSTITUTION:A can cover 1 having a curl part 3 in the outside peripheral end edge, and a can drum 2 having a flange part 4 in the opening end edge are installed in a pressure chamber 10. After pressurizing the inside of its chamber 10 to prescribed pressure, the curl part 3 of the can cover 1 is pressed against the flange part 4 of the can drum 2, Pressure Po in the chamber 10 is made lower than prescribed pressure, and while holding pressure Pi in the can higher than the pressure Po in the chamber 10, seaming is executed by a seaming roll 11 and a seaming jig consisting of a receiving die 13. As a result, the pressure closed container having an excellent sealing-up performance which is free from deformation, and also, generates no air leakage extending over a long period can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a can lid seaming method.

[Conventional technology]

Generally, tennis balls and the like are shipped in pressurized airtight containers in order to maintain the internal pressure of the ball.

Traditionally, metals such as tin plate have been mainly used for the can lid and can body of pressurized airtight containers, and the so-called double seaming method has been used to join the can lid and can body. . As shown in FIGS. 8 to 11, conventionally, the can 1ja has a curled portion C on its outer peripheral edge, and the can body has a flange portion F on its opening edge, and when tightening, Set the above-mentioned can lid a and can body into a pressurizing chamber with a seaming jig such as a seaming roll inside, pressurize the inside of the chamber to a predetermined pressure, and apply the pressure to that pressure. While holding the can lid a, the curled portion C of the can lid a was pressed (pressed) against the flange portion f of the can body, and a seaming process (double seaming process) was performed.

At this time, the curled portion C and the flange portion f must be strongly pressed together before seaming to obtain good seaming.

[Problem to be solved by the invention]

Recently, it has been used as a pressurized airtight (storage) container for tennis balls, etc.
Cans with plastic cans (called plastic cans) have become popular. The above-mentioned can bodies are molded by injection blowing using plastic materials such as polyethylene terephthalate and polyvinyl chloride, but the rigidity is significantly lower than that of conventional can bodies such as tinplate, and as shown in Figure 8 or As shown in Fig. 9, when the can lid a is strongly pressed against the can body while the chamber is pressurized, the can body partially dents e, causing so-called buckling.
, the can lid a is deformed as shown in Figure 8 or 9, or the can w
The shape of the flange part f of 4b deforms so that it is not a perfect circle, causing a misalignment relative to the curl part C, and if the seaming process is performed in this state (when it is taken out from the chamber)
As shown in FIG. 10, the can lid a is tilted, or as shown in FIG. 11, the can lid a is partially detached from the flange portion f or bent.

In the state shown in FIGS. 10 and 11, air leakage occurs, and the sealing performance of the pressurized sealed container is unreliable.

As a countermeasure, it may be possible to reduce the force with which the can lid is pressed against the can body, but it has been found that the seaming condition worsens.

SUMMARY OF THE INVENTION An object of the present invention is to provide a seaming method capable of obtaining a pressure-tight (storage) container that does not deform and has excellent sealing performance that prevents air leakage over a long period of time.

[Means for Solving the Problems] In order to achieve the above object, the present invention is a method of seaming while maintaining the pressure inside the can higher than the pressure outside the can.

Further, a can lid having a curled portion on the outer peripheral edge and a can body having a flange portion on the opening edge are installed in a pressurizing chamber, and after pressurizing the inside of the chamber to a predetermined pressure, the can lid is A method in which the curled portion of the can body is pressed against the flange portion of the can body, the pressure in the chamber is lowered than the predetermined pressure, and seaming is performed while maintaining the pressure in the can higher than the pressure in the chamber. be.

In addition, a can lid having a curled portion on the outer circumferential edge and a can body having a flange portion on the edge of the entrance are installed in a pressurizing chamber that has a tightening jig such as a tightening roll inside. ,
After pressurizing the inside of the chamber to a predetermined pressure, the curled portion of the can lid is pressed against the flange portion of the can body, and the pressure inside the chamber is reduced to the predetermined pressure immediately before seaming with the seaming jig. In this method, the pressure inside the can is lower than the pressure inside the chamber, and the pressure inside the can is higher than the pressure inside the chamber.

[For production]

Since the pressure inside the can is higher than the pressure outside the can (chamber), the sealing is performed in a state where the pressure inside the can is higher than the pressure outside the can (chamber), so even if the can lid is strongly pressed against the can body, the expansion force due to the pressure from inside will not be applied to the can body. The can body is not easily buckled. That is, the internal pressure increases the apparent rigidity, making it difficult for local dents to occur, and the seaming can be performed with the can body in its normal shape and the flange section in a perfectly circular and horizontal state.

〔Example〕

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

An embodiment of the present invention is shown in the order of steps in FIGS. 1 to 7.

10 is a pressurized chamber, although detailed illustration is omitted,
It can be opened and sealed, and the tightening rolls 11, 12 and receivers have a tightening jig such as a die 13 (see FIGS. 6 and 7) inside.

A can lid l having a curled portion 3 on the outer peripheral edge and a can body 2 having a flange portion 4 on the opening edge are installed in this chamber 10.

The can body 2 is approximately disc-shaped and made of metal such as tin plate, and has a shallow dish-shaped recess 5 extending from the center to the vicinity of the outer periphery, and is curved in a sideways three-shape (in cross section). The formed curled portion 3 has a downwardly opening concave circumferential groove 6 when turned, and a sealing layer 7 of soft plastic, rubber, etc. is previously attached to this concave circumferential groove 6 by coating or the like.

The can body 2 has a cylindrical bottom made of materials such as polyethylene terephthalate (PET) and polyvinyl chloride (PVC) by injection blow molding. The peripheral wall is curved inwardly in a small radius to form a small curved portion 8 , and an upwardly expanding tapered wall portion 9 is connected from the upper end of the small curved portion 8 . The flange portion 4 is provided in a continuous manner in a tapered shape that widens further toward the upper end. Of course, it is also possible to omit this upwardly expanding tapered wall portion 9 and directly connect the flange portion 4 to the slightly curved portion 8, or to change the shape of the flange portion 4.

First, the can body 2 and the can lid l are installed in the chamber 10 with the top or side open, and as shown in FIGS. Apply pressure. For example, let Pi=2 atmospheres. At this time, the pressure inside the can becomes Pi=Po=2 atmospheres.

Next, the curled portion 3 of the can lIl is pressed against the flange portion 4 of the can body 2. That is, when the mold 13 is pressed in the direction of arrow F (by a reciprocating drive mechanism not shown), the receiver is pressed into a sealed state by the seal layer 7.

Therefore, the pressure Po in the chamber 10 is lowered below the predetermined pressure (2 atm) by discharging the gas from the chamber 10 as indicated by the arrow A in FIG. For example, the zero can internal pressure Pi is maintained at the above-mentioned 2 atmospheres, and as shown in FIG. 4, the relative internal pressure indicated by the small arrows p... acts on the can body 2. Therefore, I immediately used a seaming jig to tighten the seams shown in Figures 5, 6, and 7.
As shown in the figure, so-called double seaming is performed. At this time, as shown in FIG. 6, the receiver is pressed between the conical curved surface of the mold 13 and the roll 11, bending the curled part 3 of the can lid l under the flange part 4 of the can body 2, and then , the other roll 1 as shown in Figure 7.
In step 2, the curled portion 3 and the flange portion 4 are tightly pressed together in a flat spiral shape (in cooperation with the sealing layer 7) to be sealed. In the states shown in FIGS. 6 and 7, even if a pressing force F' is applied to strongly press the can lid l and press it against the can body 2,
Pi>P.

As a result, the pressure difference P always acts in the direction of expanding the can body 2, increasing the apparent rigidity of the can body 2 and causing local dents (see symbol e in Figure 8 or 9). ).

Thereafter, the chamber 10 may be opened and the sealed can may be taken out.

Note that a plurality of chambers 10 can be used as a rotary table.
It is desirable that the above-mentioned steps be performed continuously by arranging them at equal pitches around the circumference.

In addition, by connecting the exhaust in the direction of arrow A in Fig. 3 to a vacuum pump and setting Po below atmospheric pressure (negative pressure), the pressure difference P between Figs. Sometimes it is preferable to make it bigger.

Of course, the pressures Pi and Pi mentioned above can be freely increased or decreased, and the point is that during the seaming process, the pressure Pi inside the can is changed from the pressure outside the can (
It is sufficient to keep the chamber pressure higher than Po, and the can body 2
The same pressure difference may be determined depending on the wall thickness, dimensions, shape, material, etc. of the can body 2. The present invention can also be applied to a thin metal can body 2.

〔Experimental result〕

Comparison of injection blow-molded PET cans with an average wall thickness T around the flange of the can body of 0.3 m, and a tin can lid with a height of 270 mm, seamed using the following two methods. I experimented.

Method ■: Conventional example (at a specified pressure inside the chamber) method of seaming and tightening), 1000 pieces.

Method ①: Method of the present invention (method of pressurizing the chamber to 2 atmospheres, opening the exhaust valve with the can body and can lid in pressure contact, reducing the pressure to atmospheric pressure, and immediately performing seaming), 1000 pieces.

The experimental results are shown in the table below. It was as per 1.

(Hereinafter, blank space) From Table 1 above, according to method ① of the present invention, can lid 1 (
The number of deformations (of the seaming part) can be significantly reduced to 12, and
Even if it was deformed, no air leakage occurred. Furthermore, after one month had passed, 67 more air leaks occurred in the conventional method (2), whereas no air leaks occurred in the method (2) of the present invention.

〔Effect of the invention〕

This prevents buckling and denting of the can body 2 during seaming, maintains the perfect circle of the flange portion 4, allows the can lid to be relatively accurately positioned, securely seals the can lid, and prevents deformation of the can lid l. Also, air leakage can be prevented, and it can greatly contribute to improving the quality of pressurized airtight containers in which tennis balls and the like are sealed under pressure. Further, it is possible to use a material with low rigidity such as plastic as the can body 2.

[Brief explanation of drawings]

Fig. 1 is a simple explanatory diagram showing the state during pressurization, Fig. 2 is an enlarged view of the main part, and Fig. 3 is a simple explanatory diagram showing the state during depressurization.
FIG. 4 is an enlarged view of the main part, FIG. 5 is a simplified explanatory view showing the state during tightening, and FIGS. 6 and 7 are enlarged views of the main part at that time. FIGS. 8 to 11 are illustrations of problems in the conventional example. Pi, Pi...pressure, 1...can lid, 2...can body,
3... Curl part, 4... Flange part, 10... Pressure channel λ, IL 12... Roll.

Claims (1)

[Claims] 1. A method for seaming a can lid, characterized in that seaming is performed while maintaining the pressure P_i inside the can higher than the pressure P_o outside the can. 2. Installing a can lid having a curled portion on the outer peripheral edge and a can body having a flange portion on the opening edge in a pressurizing chamber,
After pressurizing the inside of the chamber to a predetermined pressure, the curled part of the can lid is pressed against the flange part of the can body, the pressure P_o in the chamber is lowered than the predetermined pressure, and the inside of the can is A can lid seaming method characterized by performing seaming while maintaining pressure P_i higher than pressure P_o in a chamber. 3. The can lid tightening method according to claim 2, wherein the can lid is made of metal and the can body is made of plastic. 4. Install a can lid having a curled portion on the outer circumferential edge and a can body having a flange portion on the opening edge into a pressurized chamber having a tightening jig such as a tightening roll therein. After pressurizing the inside of the chamber to a predetermined pressure, press the curled part of the can lid against the flange part of the can body, and reduce the pressure P_o in the chamber immediately before seaming with the seaming jig. A can lid seaming method characterized in that seaming is performed in a state where the pressure inside the can is lower than the predetermined pressure and the pressure P_i inside the can is higher than the pressure P_o inside the chamber. 5. The can lid tightening method according to claim 4, wherein the can lid is made of metal and the can body is made of plastic.