JPH0333578B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to metal containers, and particularly to metal containers such as metal cans filled with beer, soft drinks, etc. and sealed. (Prior art) The metal cans commonly used today are sealed by joining a can lid to the can body filled with contents such as beer or soft drinks using so-called "double seaming". There is. Double seaming is the process of wrapping the curl of a can lid, whose outer periphery is bent into a predetermined shape, into a flange formed at the end of the can body from the outside, and then crimping the same part from the outside. In this method, the can body and can lid are joined together, and the can container is kept sealed by intervening a packing made of a rubber-like material (sealing compound) that is applied to the inside of the curled portion of the can lid. In other words, seaming is usually performed in two steps.In the first step, the first seaming roll curls the can lid, fits and rolls the flange of the can body, and in the second step, the second roll is performed. This part is crimped with a tightening roll and the airtightness is maintained by filling the space inside the crimping compound with sealing compound. Next, a seaming process that is a conventional method for manufacturing metal cans will be described with reference to FIGS. 9 to 11. First, as shown in Fig. 9-a, the can lid 22 is placed over the can body 21, the lifter plate 23 on which the can body 21 is placed is raised, and the seaming chuck 24 is attached to the can as shown in Fig. 9-b. It is fitted inside the lid 22.
The state at this time is shown in FIG. 10-a, in which the curled portion 22c of the can lid 22 is placed on the flange portion 21f of the arc-shaped can body 21, and the seaming chuck 24 is placed on the inner peripheral surface of the can lid 22. It is fitted. Next, as shown in FIG. 9-c, while rotating the seaming chuck 24, the can body 21 held by the lifter plate 23, and the can lid 22, the first seaming roll 25 is moved to the curled portion 22c of the can lid 22. to press against. The state at this time is shown in FIG. 10-b, and the first seam is formed along the shape of the roll group 25a of the first seam roll 25. During this first tightening, a predetermined pushing force is applied by the lifter to the lifter plate 23, a predetermined pressing force in the vertical direction is applied to the can body 21 and the can lid 22, and the can body flange 21f is bent downward. At the same time, the can lid curl 22c is rolled up along the first seaming roll groove 25a. Then, the first seaming roll 25 moves away, and then the second seaming roll 26 approaches and crushes the first seaming to form a second seaming. The state at this time is shown in FIG. 10-c, and the second seam is formed along the shape of the roll groove 26a of the second seam roll 26. During this second seaming, the seaming chuck 24
A predetermined pressing force is applied between the can body 21 and the can lid 22. FIG. 11 shows a sectional view of the seaming portion of the metal can formed through the first and second seaming steps. In the figure, reference numeral 23 is a sealing compound. (Problem to be solved by the invention) However, the main parts regarding the formation of seaming can be simplified and considered as the shape and size of the space formed by the lip of the chuck and the groove of the roll, and the pushing up force from below. Can be done. Therefore, the major preconditions for obtaining good seaming are the proper lip shape and position adjustment of the seaming chuck as conditions on the can seamer (sealing machine) side.
An appropriate groove shape of the second seaming roll and an appropriate pushing force of the position adjustment lifter are required.
On the other hand, the requirements for metal cans include the thickness of the can body that can withstand the pressure applied to the can body, the dimensions of the regular can body and can lid, the curl of the can lid, the proper formation of the can body flange, and the proper fit. The state of application of the compound, etc. is required. In other words, when a seamer (sealing machine) joins the can body and can lid, a predetermined vertical load (approximately 100 kg) is applied to the can body, so the can body must be thick enough to withstand that load. However, there is a problem in that it hinders thinning of the can body. Further, as mentioned above, the can bodies and can lids of metal cans require high shape and dimensional accuracy, and in particular, there is a problem in that the can lid curl and the can body flange are required to be properly formed. On the other hand, the seamer side also requires various conditions, especially the shape and dimensional accuracy of the seaming chuck and seaming roll, which are the component parts of the seamer. There is a problem in that highly accurate positioning is required, and the seamer mechanism is complex and requires precise adjustment. The present invention was devised in view of the above-mentioned circumstances, and its purpose is to reduce the thickness of the can body of metal cans and to reduce the overlapping area of the can lid and can body required for joining, thereby reducing the amount of material used. In addition, the can bodies and can lids that make up metal cans have high shape accuracy,
To provide a metal container that does not require dimensional accuracy and can simplify the structure and adjustment method of a device used for sealingly joining a can body and a can lid. [Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a can body made of a bottomed cylindrical body and a can lid that seals the mouth of the can body. In the metal container, the upper part of the can body is formed into a tapered shape so that the outer diameter gradually decreases toward the opening, a tapered outer circumferential surface for joining is provided at the upper end, and the can lid is provided with a tapered outer circumferential surface for joining. An inner peripheral surface for joining is provided with a shape corresponding to the outer peripheral surface for joining, and after filling the can body with contents, the outer peripheral surface for joining and the inner peripheral surface for joining are bonded together by thermoplastic bonding. It is characterized by being adhesively sealed with an adhesive. (Function) The present invention uses the above-mentioned means to bring the tapered outer circumferential surface of the can body and the tapered inner circumferential surface of the can lid into close contact with each other by interposing an adhesive between the two, and then A predetermined pressure is applied between the can lid and the can lid, and the two can be adhesively sealed by heating. (Example) Hereinafter, a first example of the metal container according to the present invention will be described.
This will be explained with reference to FIGS. 6 to 6. FIG. 1 is a sectional view of a metal can 1 constituting a metal container, and the metal can is constructed by joining a can body 2 and a can lid 3 with a thermoplastic adhesive 4. The can body 2 is made of a cylindrical body with a bottom, and the upper part of the can body 2 is formed at a predetermined angle θ (preferably θ is within the range of 20° to 60°) inside the cylindrical body, as shown in FIG.
The joining outer circumferential surface 2a is bent by neck-in processing at an angle of . The outer diameter of this joining outer circumferential surface 2a gradually decreases toward the upper end, but the slope thereof does not necessarily have to be linear. On the other hand, the can lid 3 has an inner circumferential surface 3 for joining which has a shape corresponding to the above-mentioned outer circumferential surface 2a for joining.
a, and the inner diameter of this joining inner peripheral surface gradually increases toward the lower end. In addition,
The outer periphery of the tip of the can lid 3 is rounded to prevent danger. Next, the process of sealing the can body 2 and the can lid 3 will be described with reference to FIGS. 3 to 5. First, as shown in FIGS. 3 and 4, the outer peripheral surface 2a for joining on the can body side or the inner peripheral surface 3 for joining on the can lid side.
Apply adhesive 4 to either a. Also, apply silicone compound 5 to the can body 3. When the can body 2 filled with the contents 6 is placed on the lifter 7 as shown in FIG. 5, the can lid 3 is placed over the can body 2. Next, the lifter 7 rises, and the chuck 8 crimps the can body 2 and can lid 3 (the crimping load is 40 kg).
The following is fine. ) Then, using high frequency sealer 9,
The entire periphery of the joint is heated to melt the adhesive 4 to adhesively seal the can body 2 and the can lid 3. The electrode portion of the high-frequency sealer 9 used at this time has a structure that allows cooling water to flow therethrough, and has a structure that allows cooling immediately after the heating of the joint portion is completed. After this cooling process, the lifter 7 is lowered and the metal can 1 is discharged. FIG. 6 is an explanatory diagram showing an automatic sealing process, in which an insulator 11 such as Bakelite is attached to a turret 10 made of aluminum material, and the turret 10 is
A terminal 12 of a high frequency generator is provided above the turret 10, and when the metal cans to be welded come to the terminal 12 as the turret 10 rotates, the entire circumference of the joint is heated by the induced current. Therefore, the outer circumferential surface 2 for joining of the can body 2 of this embodiment
a forms a tapered portion that gradually becomes smaller in diameter as it goes toward the upper end, while the inner circumferential surface 3a for joining of the can lid 3 forms a tapered portion that gradually becomes larger in diameter as it goes toward the lower end. When it is placed over the body 2, it has excellent centering properties, and since the tapered parts fit together, it has excellent adhesion. In the embodiment shown in FIG. 1, a sealing compound was interposed between the can body and the can lid. The sealing effect may be enhanced by applying an adhesive 4 between the upper end of the holder and the upper end of the holder. Furthermore, as shown in FIG. 8, it is also possible to provide an outwardly curled portion 2c at the upper end of the can body 2 to more actively prevent the end surface of the can body from coming into contact with the contents. (Experimental Results) In order to examine the practicality of the metal containers made in this way, the leakage was investigated by pressure resistance and drop tests, and the results are shown in Table 1 below. The internal pressure of canned products such as beer and carbonated drinks is 2 to 3 kg/cm ² under normal storage and consumption conditions, and 4 to 5 kg/cm 2 even under slightly poor conditions, and the internal pressure of canned products such as beer and carbonated drinks is 2 to 3 kg/cm ² under normal storage and consumption conditions. The maximum standard value for the pressure resistance of metal cans after seaming is 7.5Kg/ ^cm2 . According to Table 1, the instantaneous pressure resistance of this container is 8 kg/cm ² or more, and large deformation (buckling) occurs before the adhesive part breaks. Therefore, it can be said that this container has the same sealing performance as double seaming, which is the conventional sealing method for metal cans. In addition, we manufactured a can product by filling this container with 4 gas voluminous carbonated beverage and sealing it, and examined its sustained pressure resistance and drop impact strength at 40°C for 2 hours.
It is shown in 1. No leaks occurred in either case.
It can be said that this container has practical performance in these respects as well.

【table】

[Table] (Effects of the Invention) As is clear from the description of the embodiments, according to the present invention, the can body and can lid are adhesively sealed with an adhesive, so that the can body and can lid are sealed together. There is no need to apply an excessive vertical load to the can body during joining, and the can body can be made thinner. Furthermore, depending on the selection of the adhesive, it is possible to reduce the overlapping area between the can lid and the can body required for joining the can lid and the can body. Moreover, since the can body and the can lid do not require high shape accuracy and dimensional accuracy, it is possible to reduce the manufacturing cost of these container components. Further, according to the present invention, there is no need to seal the can body and the can lid by seaming as in the conventional method, so the structure and adjustment method of the device used for sealing can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the metal container according to the present invention, FIG. 2 is an enlarged sectional view of the main part of FIG. 1, and FIGS. 3 to 6 are seaming diagrams of the embodiment shown in FIG. 7 is a cross-sectional view of another embodiment of the present invention, FIG. 8 is a cross-sectional view of still another embodiment of the present invention, and FIGS. 9 and 10 are diagrams of a conventional metal container. FIG. 11, an explanatory diagram showing the seaming process, is a sectional view of a conventional metal container. 1...metal can, 2...can body, 3...can lid, 4...
...adhesive, 5...sealing compound.

Claims (1)

[Claims] 1. A metal container comprising a can body made of a cylindrical body with a bottom and a can lid that seals the mouth of the can body,
The upper part of the can body is formed into a tapered shape so that the outer diameter gradually decreases toward the opening, and a tapered outer peripheral surface for joining is provided at the upper end, and the can lid is tightly attached to the outer peripheral surface for joining. After providing an inner circumferential surface for joining with a shape corresponding to fit, and filling the can body with contents, the outer circumferential surface for joining and the inner peripheral surface for joining are adhesively sealed with a thermoplastic adhesive. A metal container featuring: 2. The metal container according to claim 1, wherein the angle θ of the joint surface between the can body and the can lid is within a range of 20° to 60° with respect to the vertical direction.