JP2005170470A - Can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To examine the inner pressure of a sealed can containing a content highly precisely. <P>SOLUTION: An annular projection 13 which projects outward in the can axial direction is formed on the outer edge of the bottom 11 of the can 10. The annular projection 13 has a ground contact part 14 on the end thereof, and an inner peripheral wall 15 which is continuous with the ground contact part 14 radially on the inside thereof and rises in the can axial direction. A sloped wall 19 is formed continuously on the upper end in the can axial direction of the inner peripheral wall 15 to extend inward in the radial direction and upward in the can axial direction via a first recessed curving surface 18. On the sloped wall 19, a flat panel part 21 is formed continuously to extend radially inward via a second recessed curving surface 20. The diameter ψA of the panel part 21 is 0.47 to 0.82 times of the diameter ψB of a ground contact surface 50a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the present invention, the diameter of the can which is filled and sealed is the smooth surface of the bottom of the can in a state where the can is turned upside down so that a space is formed inside the bottom of the can. The present invention relates to a can suitable for inspecting the can internal pressure by forcibly exciting the central portion in the direction by electromagnetic induction.

  Traditionally, low-acid beverages such as coffee with milk are filled in aluminum positive pressure cans (filled with liquid nitrogen) or steel negative pressure cans, sealed, retort sterilized, then packed in cases and placed on pallets. Loaded. The cans packed in the case are allowed to stand for about 7 days, and then a can internal pressure inspection is performed for each case by so-called percussion to check for leaks. This is because if there is a fine pinhole in the can, it will cause a slow leak, so even if the internal pressure of the can is measured immediately after filling, the internal pressure of the can will not change much before filling, and there will be no problem with the presence or absence of leakage. Because there is. In addition, when the content is a low-acid beverage, in general, after filling the can with the content, nitrogen gas is filled to prevent oxidation of the content.

  By the way, as a means for inspecting the can internal pressure by the above-mentioned percussion, the can filled with the contents and sealed in a state where the can is turned upside down so that a space is formed inside the bottom of the can. Of the bottom of the can, the central portion in the radial direction, which is a smooth surface, is forcibly excited by electromagnetic induction, and the peak frequency calculated by capturing the reverberation from the can at this time, the preset can internal pressure value and the peak A method for inspecting the internal pressure of the can based on the correlation with the frequency is known (for example, see Patent Document 1 below).

  Here, the can has a configuration in which a can lid having a pull tab or the like is wound around one opening portion of a cylindrical body, and a bottom lid whose entire surface is a substantially flat surface is wound around the other opening portion. A three-piece can, a two-piece can with a structure in which the can lid is wound around an opening of a bottomed cylindrical body formed by drawing and ironing a metal plate, and one opening of the cylindrical body A bottle part with a cap having a three-piece structure in which a neck part is formed to form a base part, a cap is screwed onto the base part, and the bottom lid is wound around the other opening part, A two-piece bottle with a cap having a structure in which a neck portion is formed on the opening of the bottom cylindrical body to form a base portion and a cap is screwed to the base portion is mainly supplied.

  Among these cans, the bottom of the two-piece can and the bottle can with a two-piece structure is generally a smooth dome that is recessed toward the inside of the can body, and the outer periphery of the dome is located outside the can axis. The ring-shaped convex part includes a grounding part at the tip, and an inner peripheral wall standing in the radial direction of the grounding part and rising in the can axis direction. The inner peripheral wall is configured to be continuous with the dome portion via a concave curved surface portion that is recessed toward the inside of the can body.

Conventionally, when inspecting the internal pressure of this type of can, the hitting test is generally performed by forcibly exciting the dome portion in the inverted posture.
However, in this type of can, due to the shape of the dome portion, even if the internal pressure of the can increases, a compressive force mainly inward in the radial direction is generated, and it is difficult to bulge and deform outside the can body. . Therefore, there is a problem that even if the internal pressure of the can changes, the reverberation sound due to the forced excitation hardly changes, and it is difficult to perform a high-precision internal pressure inspection. In particular, it is difficult to inspect minute changes in internal pressure, and in some cases, a good can is judged as a defective can, and conversely, a defective can is judged as a good can.

As a configuration for solving such a problem, as disclosed in Patent Document 2 below, an annular recess recessed inside the can body is continuously provided at the upper end of the inner peripheral wall in the can axis direction. There is known a can in which a flat central panel portion that is continuous through a corner portion that is convex to the outside of the can body is continuously provided on the radially inner side of the can body. With this configuration, the flat central panel bulges and deforms relatively linearly in response to changes in the internal pressure of the can, and the tensile state also changes, enabling highly accurate internal pressure inspection to be realized. It will be.
JP 49-34376 JP 2000-16418 A

  However, the conventional can has a problem in that the pressure strength and the drop strength are lowered because the corner portion, which is convex to the outside of the can body, is connected to the outer edge of the flat central panel portion.

That is, in general, the pressure strength is evaluated by a can internal pressure value when the central panel portion is swelled and deformed by a predetermined amount to the outside of the can body, and the drop strength is to increase the can internal pressure to a predetermined value, Evaluation is based on the amount of deformation by which the dome bulges due to the impact force that the can receives when the ring is naturally dropped from a predetermined height position with the grounding portion of the annular convex portion facing downward.
Therefore, since the direction of the force acting on the can bottom due to the increase in internal pressure and the generation of impact force coincides with the protruding direction of the corner portion, the conventional concave curved surface portion (the force acting on the can bottom) In comparison with a can having a structure having a convexity in the direction opposite to the above direction, the proof strength against the force is reduced, that is, the pressure strength and the drop strength are reduced.

  The present invention has been made in view of the above circumstances, and can accurately check the internal pressure of a can filled and sealed with contents, and even in such a configuration, the occurrence of a decrease in pressure resistance and drop strength is generated. It aims at providing the can which can be controlled.

In order to solve the above-described problems and achieve such an object, the present invention proposes the following means.
In the invention according to claim 1, an annular convex portion that protrudes outward in the axial direction of the can is formed at the outer edge portion of the can bottom, and the annular convex portion is connected to the grounding portion at the tip and the radially inner side of the grounding portion, A can having an inner peripheral wall that rises in the can axis direction, and an inclined wall that extends radially inward and upward in the can axis direction via a first concave curved surface at the upper end of the inner peripheral wall in the can axis direction And a flat panel portion extending inward in the radial direction via the second concave curved surface portion is connected to the inclined wall, and the diameter of the panel portion is the circumferential direction between the tips of the grounding portions. It is characterized by being 0.47 times or more and 0.82 times or less of the diameter of the circular shape obtained when they are successively connected to each other.

In this can, when inspecting the internal pressure of the can filled and sealed with the contents, it is possible to forcibly excite the flat panel by electromagnetic induction, and to achieve highly accurate internal pressure inspection. it can.
That is, since the panel portion is flat, the tensile state changes as well as a relatively linear deformation with respect to the change in the can internal pressure.

In particular, since the diameter of the panel portion is set within the above range, it can be accurately deformed even with a small change in internal pressure, and the tensile state will also change, realizing a highly accurate internal pressure inspection. In addition, even in such a configuration, it is possible to suppress the occurrence of a decrease in pressure resistance and drop strength.
That is, when the diameter of the panel part is set to a size exceeding the above range, the amount of deformation with respect to the increase in internal pressure becomes excessive, and the tensile state becomes difficult to change, so that when the panel part is forcedly excited, It is difficult to calculate the internal pressure value from the reverberation sound, and in some cases, even if the internal pressure value is appropriate, the panel part may be plastically deformed, and a high-precision internal pressure test cannot be realized. It is. Conversely, if the diameter of the panel part is set to a size smaller than the above range, it will not be deformed accurately with respect to minute changes in internal pressure, and the tensile state will not change easily, and high-precision internal pressure inspection cannot be realized. Because.

Moreover, since both the 1st concave curved surface part which connects an internal peripheral wall and an inclination wall, and the 2nd concave curved surface part which connects an inclination wall and a panel part are the shapes dented inside the can body. In addition, by increasing the internal pressure of the can, each portion of the bottom portion of the can is convex in the direction opposite to the deformation direction when it is about to bulge and deform outward of the can body, and is configured to resist the bulge deformation It has become.
As described above, highly accurate internal pressure measurement can be realized, and even in such a configuration, it is possible to reliably suppress the occurrence of a decrease in pressure resistance and drop strength.

  According to a second aspect of the present invention, in the can according to the first aspect, a radius of curvature inside the can of the grounding portion is 0.5 mm or more and 2.5 mm or less, and the outer side of the can of the first concave curved surface portion is set. The curvature radius is 1.0 mm or more and 8.0 mm or less.

  According to the can according to the present invention, the internal pressure inspection of the can filled and sealed with the contents can be performed with high accuracy, and even in such a configuration, it is possible to suppress the occurrence of a decrease in pressure strength and drop strength. it can.

Hereinafter, preferred embodiments of a can according to the present invention will be described in detail with reference to the drawings.
A can 10 shown in FIGS. 1 and 2 has a schematic configuration including a can body 12 and a can bottom portion 11 connected to the lower end of the can body 12 in the can axis direction.
The can 10 is made of aluminum, an aluminum alloy, or steel. In particular, in the case of an aluminum alloy, the can 10 is made of a 3000 series plate (plate thickness 0.25 mm to 0.46 mm, 0.2% proof stress 240 MPa to 320 MPa). Formed on the basis. The can 10 is formed by subjecting the disk-shaped plate material to drawing and ironing to form a bottomed cylindrical body. At this time, a can body 12 and a can bottom portion 11 as shown in FIG. 1 are formed. The And the can of the following 2 structure will be formed with the kind of process given to the can axial direction upper part of the can body 12. FIG.

The first one is connected to the upper end of the can body 12 and is gradually connected to the upper end of the shoulder in the can axis direction. And a bottle can having a male thread portion formed on the base portion and a curl portion whose upper end portion is folded outward in the radial direction. In addition, there is a bottle can with a cap having a configuration in which a cap is screwed onto the base portion.
Next, the second is a configuration in which the top end portion of the can body 12 is subjected to neck-in processing, flange processing, or the like, and then the contents are filled, and the can lid is wound around the flange portion as the opening end portion. There are two-piece cans.

On the outer edge portion of the can bottom portion 11, an annular convex portion 13 protruding outward in the axial direction of the can is formed. The annular convex portion 13 is connected to the grounding portion 14 at the tip and the radially inner side of the grounding portion 14, An inner peripheral wall 15 that rises in the can axis direction and an outer peripheral wall 16 that continues to the outside in the radial direction of the ground contact portion 14 and that extends outward in the can axis direction and outward in the radial direction are provided.
The outer peripheral wall 16 is connected to the lower end of the can body 12 in the can axis direction via a convex curved surface portion 17 that is convex outward in the radial direction.

Further, a flat inclined wall 19 extending inward in the radial direction and upward in the can axis direction via the first concave curved surface portion 18 is connected to the upper end of the inner peripheral wall 15 in the can axis direction. A flat panel portion 21 extending inward in the radial direction is continuously provided via two concave curved surface portions 20.
The thickness of the can bottom 11 formed as described above is set to 0.25 mm or more and 0.46 mm or less.
In addition, the inside of the cyclic | annular convex part 13 of the can bottom part 11 is made into the space, and this space is in the state connected with the space formed in the inside of the trunk | drum 12, as shown in FIG.

Here, the diameter φA of the panel portion 21 is set to 0.47 times or more and 0.82 times or less of the circular diameter φB obtained when the tips of the grounding portions 14 are successively connected in the circumferential direction. ing.
Here, the diameter φA of the panel portion 21 refers to the distance between opposing positions across the can axis among the radially outer ends of the panel portion 21, and the tip of the grounding portion 14 refers to the grounding portion 14. When the can 10 is placed on the flat surface 50 in a state of being directed downward in the axial direction, it refers to a portion of the outer surface of the grounding portion 14 that contacts the flat surface 50. That is, the diameter of the surface of the flat surface 50 where the tip of the ground contact portion 14 abuts (hereinafter, this portion is simply referred to as “ground contact surface 50a”) is φB.
1 and 2, the panel portion 21 has a diameter φA of 25 mm, the ground surface 50a has a diameter φB of 50.9 mm, and φA is 0.49 times φB.

The dimension of each part of the can bottom part 11 comprised as mentioned above is demonstrated.
The radius of curvature r1 inside the can of the ground contact portion 14 is set to 0.5 mm or more and 2.5 mm or less. When the radius of curvature r1 is smaller than 0.5 mm, there is a risk of manufacturing problems such as cracking in this portion when the grounding portion 14 is molded. This is because the can bottom 11 cannot be provided with necessary and sufficient pressure resistance and drop strength.
Moreover, the curvature radius r2 of the outer side of the first concave curved surface portion 18 is set to 1.0 mm or more and 8.0 mm or less. This is because if the radius of curvature r2 is not within this range, the can bottom 11 cannot be provided with necessary and sufficient pressure resistance and drop strength.
Furthermore, the distance C between the grounding surface 50a and the outer surface of the panel portion 21 is set to 6.0 mm or more and 10.0 mm or less. When the distance C is smaller than 6.0 mm, the can bottom 11 cannot be provided with necessary and sufficient pressure resistance and drop strength. When the distance C is larger than 10.0 mm, This is because there is a possibility that the portion may be torn and a manufacturing defect may occur.
The angle θ1 formed by the outer surface of the outer peripheral wall 16 and the surface of the flat surface 50 is set to 30 ° to 60 °, preferably 38 ° to 50 °, and the outer surface of the inner peripheral wall 15. And the angle θ2 formed with the can shaft is set to 0 ° or more and 6 ° or less.

  The can 10 configured as described above is sealed after the contents are filled, and a can lid is wound around the opening or a cap is screwed, and then the retort sterilization is performed. After application, they are packed in a case, loaded on a pallet, and left for about 7 days. Thereafter, all of the cans 10 in the case are turned upside down so that a space is formed in the bottom 11 side of the can 10, and from the outside of the case by an electromagnetic induction action by a vibrator. The panel unit 21 is forcibly excited. And the reverberation sound from the can 10 in this case is caught with a microphone, and a peak frequency is calculated. Thereafter, the internal pressure of the can is inspected based on the peak frequency and the correlation between the preset internal pressure value of the can and the peak frequency.

Here, about the can 10 comprised as mentioned above, the evaluation test about a punching appropriateness and a pressure strength was done. The results are shown in FIG.
As cans 10 used for this test, seven types of cans 10 are formed by varying the diameter φA of the panel portion 21 within the range of φA / φB from 0.47 times to 0.82 times among the above-described configurations. (Examples 1 to 7). Further, as a comparative example, three types of cans were formed by changing the diameter φA of the panel portion 21 so that φA / φB would not be within the above range (Comparative Examples 1 to 3). Note that the cans of these examples and comparative examples differ only in the panel diameter φA among the dimensions shown in the embodiment, and all other dimensions are the same.

Then, after filling and sealing the contents in the formed can, these are subjected to retort processing. Next, a hole is formed in the body of the can, and after the internal pressure of the can is made equal to the atmospheric pressure, an air supply needle is inserted into the hole. Thereafter, in a state where the can is turned upside down so that the bottom portion is directed upward in the can axis direction, the panel portion 21 is forcibly excited by electromagnetic induction action, and the peak frequency is calculated by capturing the echo sound. Next, when air is supplied from the air supply needle and the can internal pressure is increased by 0.1 MPa, the peak frequency is calculated again, and the amount of change in the peak frequency before and after the internal pressure increase is calculated. It can be said that the smaller the change amount of the peak frequency, the smaller the change in internal pressure can be detected.
Further, after gradually increasing the internal pressure of the can with the air supply needle, the internal pressure value when the panel portion 21 bulges and deforms a predetermined amount downward in the axial direction of the can, that is, the pressure resistance, was measured.

From FIG. 3, when φA / φB is 0.47 times or more and 0.82 times or less, it can be confirmed that when the internal pressure of the can changes by 0.1 MPa, the peak frequency changes by 350 Hz or more. It has been confirmed that can be provided. Moreover, even in such a configuration, the pressure strength is 0.70 MPa or more which is necessary and sufficient to withstand normal use, and it was confirmed that the strength reduction can be suppressed.
Although not shown in FIG. 3, after the can internal pressure is increased by a predetermined amount by the air supply needle, the can is moved to a predetermined height with the tip of the grounding portion facing downward in the can axis direction. The amount of bulging when naturally dropped from the position in the direction of the can axis was measured, and the drop strength was examined.
As a result, when φA / φB was within the above range, it was confirmed that the drop strength was substantially the same as or slightly smaller than that of the conventional can having no flat panel portion 21. Moreover, when φA / φB was larger than the above range, it was confirmed that the drop strength was greatly reduced.

  As described above, according to the can according to the present embodiment, when inspecting the internal pressure of the sealed can filled with the contents, the flat panel portion 21 can be forcibly excited by electromagnetic induction. Thus, a highly accurate internal pressure inspection can be realized. That is, since the panel part 21 is made flat, it is deformed relatively linearly with respect to the change in the can internal pressure, and the tensile state also changes.

In particular, since the diameter of the panel portion 21 is set within the above range, it can be accurately deformed even with a small change in internal pressure, and the tensile state can also be changed, thereby realizing a highly accurate internal pressure test. In addition, even in such a configuration, it is possible to suppress the occurrence of a decrease in pressure resistance and drop strength.
That is, when the diameter φA of the panel portion 21 is set to a size exceeding the above range, the deformation amount with respect to the increase in internal pressure becomes excessive, and the tensile state becomes difficult to change, so that the panel portion 21 is forcedly excited. It is difficult to calculate the peak frequency from the reverberation sound at the time, and in some cases, the panel portion 21 may be plastically deformed even with an appropriate internal pressure value, thereby realizing a highly accurate internal pressure inspection. Because you can't. On the contrary, if the diameter φA of the panel portion 21 is set to be smaller than the above range, it can be accurately deformed with respect to a minute change in internal pressure, and a high-precision internal pressure inspection can be realized without changing the tensile state. It is because it is not possible.

The first concave curved surface portion 18 that connects the inner peripheral wall 15 and the inclined wall 19 and the second concave curved surface portion 20 that connects the inclined wall 19 and the panel portion 21 are both recessed inside the can body 12. Since the inner pressure of the can increases, each portion of the bottom portion 11 of the can protrudes in the direction opposite to the deformation direction when the outer portion of the can body is bulged and deformed. It has a structure that resists deformation.
As described above, highly accurate internal pressure measurement of the can can be realized, and even in such a configuration, it is possible to reliably suppress the occurrence of a decrease in pressure resistance and drop strength.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in FIG. 1, the inclined wall 19 is configured as a flat wall extending radially inward and upward in the can axis direction, but may be a concave curved wall recessed inward of the can body 12.
Further, in the above embodiment, the can 10 is forcibly excited by electromagnetic induction action, and the correlation between the peak frequency calculated by capturing the echo sound from the can 10 and the preset can internal pressure value and the peak frequency is obtained. Although the method of inspecting the internal pressure of the can based on the above has been shown, the present invention is not limited thereto, and the present invention can be applied to any method that inspects the internal pressure of the can based on the reverberation sound obtained by forcibly exciting the can 10. It is possible to do.

  The internal pressure inspection of the can filled and sealed with the contents can be performed with high accuracy, and even in such a configuration, it is possible to suppress the occurrence of a decrease in pressure strength and drop strength.

It is the expanded sectional side view shown as one Embodiment of the can which concerns on this invention. It is a schematic block diagram of the can shown in FIG. It is a figure which shows the result of having formed several cans by varying the diameter of a panel part, and evaluating the punching appropriateness and pressure-resistant strength about these cans.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Can 11 Can bottom part 13 Annular convex part 14 Grounding part 15 Inner peripheral wall 18 1st concave curved surface part 19 Inclined wall 20 2nd concave curved surface part 21 Panel part φA Diameter of panel part φB Diameter of ground surface (circular diameter) )

Claims (2)

An annular convex portion protruding outward in the can axis direction is formed on the outer edge of the can bottom,
The annular convex portion is a can having a structure including a grounding portion at a tip and an inner peripheral wall that is continuous with a radially inner side of the grounding portion and rises in a can axis direction,
An inclined wall extending radially inward and upward in the can axis direction through the first concave curved surface portion is continuously provided at the upper end in the can axis direction of the inner peripheral wall,
A flat panel portion extending inward in the radial direction via the second concave curved surface portion is connected to the inclined wall,
The diameter of the panel portion is 0.47 times or more and 0.82 times or less of the circular diameter obtained when the tips of the grounding portions are successively connected in the circumferential direction. Cans. The can according to claim 1,
The radius of curvature inside the can of the grounding portion is 0.5 mm or more and 2.5 mm or less,
The can characterized in that the radius of curvature of the outer side of the first concave curved surface portion is 1.0 mm or more and 8.0 mm or less.

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