JP2018177250A - Can body and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bottle can with a screwed spout which is tapered and diameter-reduced in the necking process, with a function to restrain occurrence of bridge cut-off when roll-on molding a cap with a bridge to the spout.SOLUTION: The bottle can 1 has a body 1A, a shoulder 1B and a spout 1C. The shoulder 1B is tapered and diameter-reduced as extended from the body 1A, and the spout 1C is extended from the shoulder 1B in the direction of the can axis P. And the R part 6 is formed at a boundary of the shoulder 1B and the spout 1C, with its curvature radius r1 on the cross section along the can axis P of 2-6 mm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bottle-shaped can and a method of manufacturing the same.

  In the case of a bottle-shaped can, a container with a screw cap, which has been screw-formed at the mouth, is widely used. In such a bottle-shaped can, a blank made of a material such as aluminum alloy is punched into a circular shape, which is drawn to obtain a bottomed cylindrical cup molded body, which is further drawn and ironed. After processing (DI molding) to obtain a cylindrical can with a bottom, in the necking step, a tapered shoulder and a cylindrical mouth (or neck) are formed. Thereafter, the mouth is screwed, and if necessary, the tip is curled through a further necking step.

  In the above-mentioned necking step, a plurality of molds (neck-in molds) are used, and diameter reduction drawing (necking) is performed in stages. The mold is formed with a core (center ring) disposed inside the opening of the bottomed cylindrical can and a cylindrical shape, and the opening of the bottomed cylindrical can is inserted therein And an outer part (aperture type or insert). And in the process of moving forward along the can axis with respect to the bottomed cylindrical can, the throttling surface formed on the tip inner peripheral surface of the outer core portion is the outer peripheral surface of the bottomed cylindrical can. While the sliding contact is made, this is pressed radially inward and the outer peripheral surface of the core portion supports the inner peripheral surface of the opening which is being pressed, whereby diameter reduction drawing of the opening is performed (see below patent) Reference 1).

In addition, in order to improve the strength of the mouth and shoulder upper end, at least one or more taper-like tapered upper ends around the upper end of the tapered shoulder gradually expanding in the radial direction from the lower end of the screw at the mouth. A threaded metal can having a smooth concave portion that curves inward and a smooth convex portion that curves at least one or more has been proposed (see Patent Document 2 below).

Unexamined-Japanese-Patent No. 2006-150426 JP 2001-213416 A

  Conventionally, a curved surface with a radius of curvature of 8 to 10 mm is formed on the squeezed surface of the inner peripheral surface of the tip of the outer core portion in the die for reducing diameter drawing exemplified in Patent Document 1 described above. It is possible to reduce the diameter of the smooth opening with reduced wrinkles. When a shoulder portion which is tapered in a tapered shape is formed using such a mold, a curvature at a cross section along the can axis at the connecting portion (neck) of the shoulder portion and the mouth portion formed in the final stage A radius of 7 to 8 mm will be formed.

  The bottle-shaped can thus obtained by screwing, curling or the like to the neck portion having a diameter-reduced shape, is used in roll-on molding of a cap with a bridge on the thread of the neck portion in the capping step. Depending on the molding conditions, deformation of the mouth due to insufficient deformation resistance occurs, and it has been confirmed that the bridge is easily broken.

On the other hand, although it seems that deformation resistance of the mouth is given, the screwed metal can that improves the strength of the mouth and the upper end of the shoulder of Patent Document 2 mentioned above is supposed to be given deformation resistance. In order to form a curved recess and an outwardly curved protrusion, the number of processes increases, the amount of indentation, the molding load increase, and damage to the outer surface varnish and inner surface paint of the can, dents, buckling and the like occur. There is a fear.

  The present invention is proposed to address such problems. That is, in the case of a bottle-shaped can in which the neck portion having a diameter-reduced shape in the necking process is subjected to screw processing etc., when roll-on forming a cap with a bridge on the neck portion, It is an issue to suppress the occurrence of bridge breakage.

  In addition, in order to roll-on form a cap with a bridge in the mouth, when giving deformation resistance to the mouth of the metal can, it prevents damage to the outer surface varnish and inner surface paint of the can, dents, buckling, etc. The problem is that.

In order to solve such a subject, the can of the present invention comprises the following composition.
A bottle-shaped can body, comprising: a shoulder portion tapered from the body portion in a tapered shape; and a mouth portion extending from the shoulder portion along the can axis direction, the can shaft being connected to the shoulder portion and the mouth portion The can provided with the R section which becomes 2-6 mm in radius of curvature r1 in the section which met in the direction.

Moreover, the manufacturing method of the can of the present invention comprises the following composition.
A method for manufacturing a bottle-shaped can, wherein after forming a shoulder and a mouth by a necking step, a necking step of forming a diameter reduction step on the mouth is performed, and simultaneously with the neck necking step. A reforming process is performed in which the radius of curvature in the cross section along the can axis direction in the R section is formed by pressing the reform molding surface against the R section of the connection between the shoulder and the opening. Method of manufacturing cans.

  ADVANTAGE OF THE INVENTION According to the can of this invention, when roll-on-forming the cap with bridge to an opening part, generation | occurrence | production of bridge breakage can be suppressed.

  The present invention provides various causes of bridge breakage which occur when roll-on forming a cap with a bridge in an opening, in a bottle-shaped can having a screw-processed opening and the like which has been subjected to diameter reduction drawing in the necking step. As a result of investigation, it was found that the cause of the deformation of the opening due to the skirt roll load at the roll on molding of the cap, and the invention was completed.

  That is, conventionally, in the state of the connection curved surface of the shoulder and the mouth of the can formed at the final stage of the necking step, the mouth is easily elliptically deformed by the skirt roll load at the roll on molding of the cap. It is considered that, when the mouth portion is elliptically deformed during roll-on molding of the cap, a tensile load in the circumferential direction is applied to the side surface of the cap on the long diameter side of the deformed state, which tends to cause bridge breakage. Based on such a hypothesis, when the curvature radius r1 of the R portion of the connection between the shoulder and the mouth of the can is reformed into a predetermined range (2 to 6 mm, preferably 3 to 5 mm), It has been confirmed that deformation resistance is enhanced and the probability of occurrence of bridge breakage is significantly reduced.

The method for manufacturing a can according to the present invention is a can that improves the deformation resistance of the mouth simultaneously with the neck necking step of forming a diameter-decreasing step that defines the formation range of the bead, the skirt, the screw, and the curl. Reforming is performed to reduce the radius of curvature of the R portion of the connection between the shoulder and the mouth. As a result, the number of steps can be reduced, and the amount of indentation and the forming load can be reduced, and damage to the outer surface varnish and inner surface coating of the can, dents, buckling and the like can be prevented.

It is a sectional view showing an important section of a can concerning an embodiment of the present invention. It is explanatory drawing which showed the necking process which shape | molds a shoulder part and an opening part ((a)-(d) has shown the procedure of one process process.). It is explanatory drawing which showed the shaping | molding state in the necking process which shape | molds a shoulder part and a mouth part ((a) is the A section enlarged view in FIG. 2, (b) is the B section enlarged view in FIG. 2.) . It is an explanatory view showing a neck necking process and a reforming process ((a) shows a neck necking process and a reforming process in the first stage, and (b) shows a neck necking process and a reforming process in the second stage ). It is the C section enlarged view in FIG. It is an explanatory view showing another embodiment of a neck necking process and a reforming process ((a) is a neck necking process and a reforming process of the first stage, (b) is a neck necking process and a reforming process of the second stage. Show). It is the D section enlarged view in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Hereinafter, the same reference numerals in different drawings denote parts having the same functions, and repeated descriptions in the respective drawings will be appropriately omitted.

As shown in FIG. 1, the can 1 according to the embodiment of the present invention is a bottle-shaped metal can having a body 1A, a shoulder 1B and a mouth 1C, and the shoulder 1B is contracted from the body 1A. The opening portion 1C is extended along the can axis P, and the bead portion 2, the skirt portion 3, the screw portion 4, and the curling portion 5 are sequentially extended from the bottom. Is formed. The shoulder portion 1B is formed in a tapered shape without a recess and has a set taper angle (neck shoulder angle) θ.

An R portion 6 is formed at the junction (neck) of the shoulder portion 1B and the mouth portion 1C in the can 1. The R portion 6 connects the shoulder portion 1A and the mouth portion 1C with a curved surface having a set curvature radius r1 and has a curvature radius r1 of 2 to 6 mm (preferably 3 to 5 mm) in a cross section along the can axis direction. It is set to be).

The necking step of forming the shoulder portion 1B and the mouth portion 1C will be described with reference to FIG. In this necking step, the core portion 10 of the mold is inserted into the opening end 1D of the can 1 and the outer core portion 11 is brought into sliding contact with the outer peripheral surface of the can 1 from the outside. , Reduce diameter diameter.

(A) to (d) of FIG. 2 show one processing step of diameter reduction drawing performed a plurality of times with different dies. As shown in (a), with the open end 1D of the can 1 opposed to the throttling surface 11A of the outer core 11 of the mold, the mold comprising the core 10 and the outer core 11 can While moving in the P direction and moving the core portion 10 to the inside of the can 1 in advance as shown in (b), the squeezed surface 11A of the outer core portion 11 is set to the open end 1D of the can 1 As shown in (c) and (d), the outer core portion 11 is further moved in the can axis P direction to perform diameter reduction drawing processing by the squeeze surface 11A of the outer core portion 11.

At this time, as shown in FIG. 3A, the throttling surface 11A is formed with the opening 1C along the throttling surface 11A, and at the moving end of the outer core portion 11 shown in FIG. As shown in (b), an R portion 6 close to the curved surface of the throttling surface 11A is formed at the junction (neck) of the shoulder portion 1B and the mouth portion 1C. At this time, assuming that the radius of curvature R0 of the diaphragm surface 11A is 8 to 10 mm, the radius of curvature Rs of the R portion 6 connecting the shoulder portion 1B and the opening portion 1C is 7 to 8 mm.

Then, after the shoulder portion 1B is formed by a plurality of (for example, 21) diameter reduction drawing processes, as shown in FIG. 4, the first outer core portion 11 (A) and the second outer core portion 11 ( According to B), the shoulder portion 1B is not formed, and the neck portion is subjected to a stepwise necking process in which the neck portion 1C is subjected to stepwise diameter reduction drawing, whereby the neck portion 1C has a two-step diameter reduction step. 1C1, 1C2 are formed. As described above, when the diameter-reduced steps 1C1 and 1C2 are formed in the mouth 1C, the deformation resistance to the compressive load from the side can be enhanced by the improvement of the section coefficient due to the step. Also by this, it is possible to suppress deformation of the opening 1C at the time of roll-on molding of the cap.

And when two steps of diameter reduction level differences 1C1 and 1C2 are formed in mouth 1C, the diameter reduction level difference of the R section and the lower part after reform which mentions skirt part 3 and bead part 2 which will be formed at a later process later. The screw 4 is formed between 1C1 and the screw 4 is formed between the two steps of the reduced diameter step 1C1 and 1C2 or between the skirt 3 and the reduced diameter step 1C2. By separately forming the bead portion 2 and the skirt portion 3 and the screw portion 4 for each level difference as described above, it is possible to increase the strength of the opening after forming each portion.

Then, at the same time as the neck necking step described above, reform molding is performed by the reform ring 12 to reduce the curvature radius Rs of the R portion 6 connecting the shoulder portion 1B and the neck portion 1C. In the reforming process, the reforming ring 12 is connected to the outer shell portion 11, and the reforming ring 12 is moved together with the outer shell portion 11 to press the reforming molding surface 12A of the reforming ring 12 against the R portion 6. Thereby, as shown in FIG. 5, according to curvature radius R01 of reforming molding surface 12A, curvature radius r1 of R section 6 of a connection of shoulder section 1B and mouth section 1C can be made small. Specifically, by setting the curvature radius R01 of the reforming surface 12A to 0.5 to 1.0 mm, the curvature radius r1 of the R portion 6 can be formed to 2 to 6 mm. The final radius of curvature r1 of the R portion 6 can be appropriately adjusted by the amount of depression of the reforming ring 12.

In the example shown in FIG. 4, in the step shown in FIG. 4 (a), the reforming step in the first step is performed by the reforming ring 12 connected to the first outer core portion 11 (A). In the process shown in b), the reforming process of the second stage is performed by the reforming ring 12 connected to the second outer core part 11 (B). As described above, by performing the reforming process in stages, smooth reforming can be performed, but by connecting the reforming ring 12 to only one of FIGS. 4A and 4B, one molding process can be performed. Reforming can also be performed.

6 and 7 show another embodiment of the mouth necking process and the reforming process. In this example, a reforming surface 12A is provided on the inner peripheral surface of the tip of the first outer core portion 11 (C) and the second outer core portion 11 (D), and the outer ring portion It is configured integrally with 11. The reform molding surface 12A has a gap with respect to the outer peripheral surface of the core portion 10. Also in this example, as shown in FIG. 7, the curvature radius R01 of the reforming surface 12A is formed to be about 0.5 to 1.0 mm.

As shown in FIGS. 6 (a) and 6 (b), in the case of performing the two-step reforming process, the first outer core portion 11 (C) has a diameter reduction aperture of the opening 1C on the inner peripheral surface thereof. A drawn surface for processing is formed, and the second outer core portion 11 (D) is separated from the reform molding surface 12A so as to release the step portion 1C1 formed by the first diameter reduction drawing. The throttling surface is formed at the same position. Also in this example, one of the two-stage reforming process can be omitted to perform the reform molding in one molding. Either one of the first outer core portion 11 (C) and the second outer core portion 11 (D) shown in FIG. It may be possible to perform reform molding.

Thus, since the can 1 according to the embodiment of the present invention is subjected to the reforming necking step and the curvature radius Rs of the R portion connecting the shoulder portion and the opening portion at the same time, the number of steps is reduced. Also, the pressing amount and the forming load are reduced, and damage to the outer surface varnish and the inner surface paint of the can 1, dents, buckling and the like are prevented.

[Example]
<Production of bottle-shaped cans>
A can is made by drawing and ironing using an aluminum metal plate, and diameter reduction drawing is performed from the open end of the can to extend the tapered shoulder portion along the can axis. Formed a mouth. Next, a two-step diameter reduction drawing process (mouth part necking step) is performed on the mouth to form a two-step diameter reduction step, and at the same time as the second diameter reduction drawing, the shoulder and the mouth are connected. The R portion of the curvature radius Rs was reformed into the R portion of the curvature radius r1 shown in Table 1 respectively. Thereafter, the bead portion and the skirt portion were formed sequentially from the lower portion between the R portion and the lower diameter step, the screw portion was formed between the two steps of the smaller diameter step, and the curl portion was formed at the tip of the mouth.
In addition, the above-mentioned reform molding was performed for each 100 cans.

<Bottled can>
Can body outer diameter: 62.20 mm, can body thickness: 0.135 mm, can body height: 132.60 mm, mouth outer diameter: 33.45 mm, thickness of screw portion: 0.34 mm, meat of shoulder upper end Thickness: 0.33 mm, thickness of lower end of shoulder: 0.21 mm, taper angle of shoulder: 28 degrees, radius of curvature Rs of connection between shoulder and mouth: 7 mm, r1: Table 1, n number: 100 each can

<Evaluation>
The following evaluation was performed about these bottle-like cans. The results are shown in Table 1.
[Bridge is broken]
An aluminum cap was applied to the screw portion of the mouth portion of the bottle-like can described above, and the skirt portion was pressed with a skirt roll load of 111 N to perform roll-on molding. At this time, occurrence of bridge breakage (number of cans) per 100 cans was visually confirmed.

As a result of the above, by setting the radius of curvature r1 of the R portion after reform molding to 2 to 6 mm, sufficient deformation resistance against roll-on molding of the cap can be obtained, and the occurrence of bridge breakage is suppressed. It can be understood that
When the radius of curvature r1 of the R portion after reform molding is formed to be less than 2 mm, the radius of curvature R01 of the reform molding surface of the reform ring must be less than 0.5 mm. There is a concern about scraping. On the other hand, when the radius of curvature r1 of the R portion after reforming is more than 6 mm, deformation resistance is reduced and bridge breakage occurs. For this reason, it is particularly preferable to set the radius of curvature r1 of the R portion after reform molding to 3 to 5 mm.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and changes in design etc. within the scope of the present invention are not limited. Are included in the present invention. In addition, the respective embodiments described above can be combined with each other by utilizing the techniques of each other unless there is a contradiction or a problem in particular in the purpose, the configuration, and the like.

1: Can body, 1A: body, 1B: shoulder, 1C: mouth,
2: bead portion 3: 3: skirt portion 3, 4: screw portion 5: curled portion 6: 6: R portion
10: core, 11: outer core,
12: Reforming ring, 12A: Reforming molding surface,
P: Can shaft

Claims (7)

It is a bottle-shaped can,
A shoulder portion tapered from the body portion and a mouth portion extending along the can axial direction from the shoulder portion;
A can having a radius of curvature r1 of 2 to 6 mm in a cross section along the can axis direction formed at the connection between the shoulder and the mouth.   The can according to claim 1, wherein the radius of curvature r1 is 3 to 5 mm.   The can according to claim 1 or 2 which has a bead part, a skirt part, a screw part, and a curl part one by one in the mouth above the above-mentioned R part. A method of manufacturing a bottle-shaped can
After forming the shoulders and the mouth by the necking process, a necking process is performed to form a step of diameter reduction in the mouth,
By pressing the reform molding surface against the R portion of the connection between the shoulder and the opening simultaneously with the necking step, the radius of curvature in the cross section along the can axis direction of the R portion is molded small. The manufacturing method of the can characterized by performing a reforming process.   The curvature radius R01 of the said reform molding surface is 0.5-1.0 mm, The manufacturing method of the can of Claim 4 characterized by the above-mentioned.   The method for manufacturing a can according to claim 4 or 5, wherein, in the mouth necking step, a two-step diameter reduction step is formed in the mouth.   Among the two steps of reduced diameter steps, a skirt portion and a bead portion are formed between the R portion and a reduced diameter step below, and a screw portion is formed between the steps of the reduced diameter steps. The manufacturing method of the can described in Claim 6.

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