JP2004017977A - Container excellent in impact test aptitude - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a container excellent in impact test aptitude even if a retort sterilization process is carried out. <P>SOLUTION: There is provided a container in which an inner pressure of the container is detected in response to a sound characterstic of vibration generated under an application of striking force. An annular bead 6 protruded to a side becoming an outer surface is formed at a circumferential edge of a flat plate segment 7, and a concave panel segment 8 notched at a side becoming an inner surface is formed at the central part of the flat plate segment 7. Accordingly, when the inner pressure is reduced after the inner pressure is increased, the deformation generated through increasing in the inner pressure returns back to its original state and the impact test aptitude is improved. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the shape of a container such as a can, and more particularly, to an internal pressure test based on acoustic characteristics when a bottom (bottom lid) is forcibly excited by electromagnetic induction, and to increase an internal pressure such as a retort process. It relates to a container that undergoes processing.
[0002]
[Prior art]
As an example of quality inspection of a sealed container product such as canned food, a canned sound inspection is known. This is an inspection method that utilizes the fact that the acoustic characteristics when a container is hit are reduced due to a decrease in internal pressure due to poor sealing of the sealed container or an increase in internal pressure due to decay. In general, the frequency increases in accordance with an increase in internal pressure.For example, the can lid is struck, or the can lid is forcibly excited by electromagnetic induction, and the accompanying vibration is detected by a sensor such as a microphone. Are within a predetermined range, and those out of the range are regarded as defective. In practice, a digit value that is 1/10 of the detected frequency (Hz) may be used instead of using the detected frequency as it is.
[0003]
Since the canning sound inspection is an inspection that determines the internal pressure of the sealed container based on the acoustic characteristics of the bottom lid and the like, the bottom of the container subjected to the inspection preferably has a large degree of deformation with respect to a pressure change. This kind of container has excellent so-called percussion suitability. Therefore, for example, the can end wall described in Utility Model Registration No. 2539918 has a peripheral annular concave portion, an annular inclined portion inclined upward, an annular flat portion, and an annular inclined portion inclined downward inside the chuck wall. And a central panel portion are formed in order from the outer peripheral side, and the central panel portion is not provided with an opening tab.
[0004]
Similar configurations are described in Japanese Utility Model Publication No. 59-31537 and Japanese Utility Model Application Laid-Open No. 56-131152. In the percussion can lid described in these publications, the periphery of the counter sink center panel is disclosed. A bead convex portion is formed near the edge, and a flat plate surface or a center extension panel portion having no dent is formed inside the bead convex portion.
[0005]
[Problems to be solved by the invention]
The invention described in the above-mentioned utility model registration No. 2539918 is an invention aimed at improving the pressure resistance strength and the drop strength to improve the hitting suitability, and includes a ridge portion around the central panel portion. Is characterized by the fact that Further, the inventions described in Japanese Utility Model Publication No. 59-31537 and Japanese Utility Model Application Laid-Open No. 56-131152 are aimed at improving the hitting aptitude while maintaining the pressure resistance. Basically lies in that a central flat plate portion is surrounded by a bead protrusion.
[0006]
However, when these conventional structures are used for so-called positive pressure cans, such as LN cans or carbonated beverage cans, which are filled with liquid nitrogen along with the contents, when the internal pressure is normal and the internal pressure is low, pinholes or improperly tightened. Since there is a remarkable difference in the acoustic characteristics from the one that has been reduced due to the leakage due to the like, the canning sound inspection can be performed to some extent accurately. On the other hand, when a canned product containing milk coffee or mixed tea is subjected to a heat treatment process such as retort sterilization, particularly when a positive pressure can is subjected to retort sterilization, the internal pressure is increased by heating. At about 640 Kpa. As a result, the can lid or bottom that gives the impact force swells outward due to the increase in the internal pressure, and then the swelling decreases due to the decrease in the internal pressure, but the deformation remains without returning to the shape before heating. I will. Therefore, even if the internal pressure is reduced due to leakage due to pinholes or improper winding, a significant difference in acoustic characteristics between the good product and the defective product due to punching hardly occurs. There was a problem that could not be done.
[0007]
The present invention has been made in view of the above technical problem, and when the internal pressure is reduced after performing a heat treatment such as a retort, a so-called shape return characteristic that returns to a shape before the heat treatment is performed. It is an object of the present invention to provide a container having improved percussion suitability by improving the density.
[0008]
Means for Solving the Problems and Their Functions
In order to solve the above-mentioned problems, the present invention provides a container in which an internal pressure is detected based on acoustic characteristics of vibration generated by the application of an impact force, wherein an outer surface is provided on a peripheral portion of a flat plate portion forming a bottom. An annular bead portion is formed so as to protrude on the side to be formed, and a concave panel portion which is depressed on the side to be an inner surface is formed at the center of the flat plate portion.
[0009]
In the present invention, as described in claim 2, an annular groove that is recessed on the side that becomes the inner surface of the container can be formed on the outer peripheral side of the annular bead portion. .
[0010]
Further, according to the present invention, the concave panel portion may have a circular shape.
[0011]
Further, according to the present invention, as described in claim 4, the depth of the concave panel portion can be configured to be smaller than the depth of the annular groove.
[0012]
Therefore, in the present invention, the inner portion of the annular bead portion is not formed in a simple flat plate shape, a concave panel portion that is recessed on the so-called inner surface side is formed in the center portion, and therefore, by a retort sterilization process or the like. When the internal pressure is increased to a maximum of about 640 Kpa, a deformation that causes the bottom to swell mainly occurs in the flat portion on the outer peripheral side of the concave panel portion. As a result, when the internal pressure of the container of the present invention is reduced, the deformation of the container tends to return to its original state, and the acoustic characteristics of the non-defective product whose internal pressure has not been reduced and the defective product whose internal pressure has been reduced by the canning sound inspection are clear. Differences occur, especially when the can pressure after retort sterilization treatment is 160 Kpa or less at room temperature, and the correlation between the can pressure and the acoustic characteristics is excellent. Inspection accuracy is improved. That is, the container has good suitability for percussion.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
A metal plate material used as a material for a so-called two-piece can or a can lid in which a can body and a can bottom are integrated is aluminum or an aluminum alloy (5052 or 5182 material) rolled to a thickness of 0.20 to 0.35 mm. In general, in the field of cans, a metal plate is used as a main material, and at least one surface (the inner side of the can) is provided with a protective coating by coating with a resin paint or laminating a thermoplastic resin film. It is an aluminum-based metal plate material for a can lid used. In addition, a steel plate having a plate thickness of 0.15 to 0.25 mm, such as an electrolytic chromic acid-treated steel plate, a Sn-plated steel plate, or a Ni / Sn-plated steel plate can be used.
[0014]
Next, the present invention will be described based on a specific example shown in the drawings. FIG. 1 shows a cross-sectional shape of a can lid (bottom lid) 1 according to the present invention. The can lid 1 is formed in a circular shape as a whole, and its outer peripheral portion is wound around an open end of a can body. A fastening flange 2 is formed. An inner peripheral wall (chuck wall) 3 forming the winding flange 2 extends to the bottom of an annular groove 4 formed along the chuck wall 3. As shown in FIG. 2, the annular groove 4 is a groove that is depressed on the side that becomes the inner surface when the can lid 1 is wound around the can body 5 and integrated.
[0015]
An annular bead portion 6 is formed on the inner peripheral side of the annular groove 4 along the annular groove 4. The outer peripheral end of the annular bead 6 does not completely coincide with the upper end on the inner peripheral side of the annular groove 4, and the outer peripheral end of the annular bead 6 is slightly inside the inner peripheral end of the annular groove 4. The edge is located.
[0016]
To describe the shape of the annular bead portion 6 more specifically, the height H is about 130 to 210%, preferably about 165% of the thickness T of the metal plate constituting the can lid 1. , For example, about 0.4 to 0.6 mm, preferably 0.5 mm. Further, it has an asymmetric cross-sectional shape in which the gradient of the inner peripheral side is smaller than the gradient of the outer peripheral side. That is, the dimensional difference between the diameter D1 of the top portion and the diameter D3 of the inner peripheral end is larger than the dimensional difference between the diameter D1 of the top portion of the annular bead portion 6 and the diameter D2 of the outer peripheral end of the annular bead portion 6. These diameters are, for example, D1 = 50.9 mm, D2 = 53.9 mm, and D3 = 46.0 mm.
[0017]
Further, the outer peripheral end, the top, and the inner peripheral end of the annular bead portion 6 are connected to adjacent portions with curved surfaces having a circular cross section. That is, the outer peripheral end portion is connected to the annular groove 4 side by a curved surface having an arc-shaped cross section of a predetermined radius R1 having a center of curvature on the outer surface side (upper side in FIGS. 1 and 2), and the top portion is connected to the inner surface side (FIG. 2 (lower side of FIG. 2), and has an arc-shaped cross section having a predetermined radius R2 having a center of curvature, and further, an inner peripheral end portion is formed by a curved surface having an arc-shaped cross section having a predetermined radius R3 having a center of curvature on the outer surface side. Side flat plate portion 7.
[0018]
Here, the flat plate portion 7 indicates the entire inner peripheral side of the annular bead portion 6; however, the flat plate portion 7 does not necessarily form a completely flat surface, but is formed on the inner surface side of the container. A recessed concave panel portion 8 is formed. When LN (liquid nitrogen) is filled into the can body 5 so that the internal pressure is in the range of 60 Pa to 160 Kpa by filling and sealing the content, for example, as shown by a symbol P1 in FIG. It has a swollen shape.
[0019]
The concave panel portion 8 is for forming a region that is elastically deformed starting from a peripheral portion thereof. That is, the flat plate portion 7 is intended to cause the same deformation as the concave panel portion 8 to be elastically deformed in the plate thickness direction starting from the vicinity of the annular bead portion 6 formed on the peripheral edge portion.
[0020]
Specifically, the shape of the concave panel portion 8 is circular, and its depth De is smaller than the depth of the annular groove 4 described above, and is about 130 to 250% of the plate thickness T, preferably about 213%. Thus, as an example, it is about 0.4 to 0.7 mm, preferably 0.65 mm. The outer diameter of the concave panel portion 8, that is, the diameter D4 at the center of a curved surface (radius of curvature R5) formed at the boundary between the concave panel portion 8 and the flat plate portion 7 is equal to the outer diameter D3 of the flat plate portion 7. It is about 41 to 46%, preferably about 44%, for example, 17.5 to 21.0 mm, preferably 20.0 mm.
[0021]
Further, the concave panel portion 8 is connected to the flat plate portion 7 with a smooth curved surface, and the central portion thereof is almost flat. With such a concave panel, the inspection characteristics are further improved as compared with the shape in which a flat (flat) concave portion connected to the flat plate portion via a taper or a curved surface unavoidable in processing. The diameter D5 of the flat portion is about 26 to 30%, preferably about 28%, of the outer diameter D3 of the flat plate portion 7, and is, for example, 12.0 to 14.0 mm, preferably 12.9 mm. The curved surface from the flat plate portion 7 to the concave panel portion 8 has a curved surface with a radius R4 having a center of curvature on the inner surface side from the flat plate portion 7 side, and a radius R5 with a center of curvature on the outer surface side smoothly following the curved surface. It is composed of a curved surface and a curved surface of radius R6 having a center of curvature on the outer surface side following the curved surface smoothly.
[0022]
As shown in FIG. 2, the can lid 1 is attached to the open end of the can body 5 by winding the winding flange 2 by a seamer (not shown). Since the can lid 1 is not provided with an opening member or portion such as a tab or a score line, it is generally used as a bottom lid. In addition, the can body 5 is a can body for a so-called three-piece can in which a metal plate is formed into a cylindrical shape, and a bottom portion of a so-called two-piece can body in which a metal plate is subjected to drawing and ironing to form a bottomed cylindrical shape. It may be any of a can body for a bottle-type can in which a mouth and neck portion is formed by applying drawing processing to a can.
[0023]
The above-mentioned can lid 1 according to the present invention can be used as a can lid for various cans. However, since it has good followability of deformation to changes in internal pressure and excellent tapping suitability, it is particularly subjected to retort sterilization treatment. It is effective as a can lid for sealed container products such as canned and bottle-shaped can products. FIG. 2 shows the shape P1 after filling of the contents and the shape before retort sterilization, the shape P3 under the internal pressure during retort sterilization, and the internal pressure after retort sterilization when used for such a product. The extracted shape P2 in the normal temperature state is shown.
[0024]
The lid material of the example is 5182 aluminum alloy material, which is shown together with the conventional example and the reference example.
[0025]
Embodiment 1
The can lid shown in FIG. 1 was tightly wound around the open end of the can body, and after filling the inside with nitrogen, the beverage was sealed and heated with a retort sterilization apparatus (120 to 125 ° C. × 20 min) to increase the internal pressure. A plurality of items were made and each was subjected to a canning sound inspection to determine a digit value. The dimensions of each part are as listed above as the preferable values. Further, the sealed can whose internal pressure was increased to a predetermined pressure was pressure-reduced by making a hole to simulate a leak, the internal pressure was set to zero, and subjected to a canning sound inspection in that state to obtain a digit value.
The measurement results are shown in FIG. In FIG. 3, the filled points indicate the results for the sealed containers that were not depressurized after the retort sterilization treatment, and the white points indicate the results for the sealed containers that were depressurized after the retort sterilization treatment.
As is clear from FIG. 3, in the sealed container having no leak, the digit value was increased in accordance with the internal pressure. On the other hand, in the sealed container leaked, the digit value became almost constant. This is presumed to be due to the return of the deformation of the can lid by releasing the internal pressure. Therefore, if the canning sound inspection is performed using the can lid according to the present invention, even if the container is subjected to the retort sterilization treatment, the defective product having a leak after the retort sterilization treatment and the good product having no leak are clearly identified. Can be distinguished.
[0026]
Embodiment 2
This is an example in which the shape of the can lid 1 shown in FIG. 1 is slightly different. In the example shown in FIG. 1, the concave panel portion is connected to the flat plate portion by three curved surfaces having radii R4, R5, and R6. On the other hand, in Example 2, the curved surface portion of R6 was eliminated, and the concave panel portion was made as flat as possible. The shape is shown in FIG. 4 as a cross-sectional shape.
The canning sound inspection using the can lid of the second embodiment is performed in the same manner as in the first embodiment, and the digitization is performed on each of the sealed container that has been subjected to the retort sterilization treatment and the sealed container that has been depressurized by imitating a leak. The value was determined. The result is shown in FIG.
As is clear from FIG. 5, as in the first embodiment, the digit value increases in accordance with the internal pressure in the leak-free sealed container, whereas the digit value is substantially constant in the leaked sealed container. Became. Therefore, if the canning sound inspection is performed using the can lid according to the present invention, even if the container is subjected to the retort sterilization treatment, the defective product having a leak after the retort sterilization treatment and the good product having no leak are clearly identified. Can be distinguished.
[0027]
Conventional example 1
The inside of the annular bead portion is a can lid having only a flat plate portion and no concave panel portion. The shape of the can lid is shown in a sectional view in FIG. The canning sound inspection was performed in the same manner as in Examples 1 and 2. FIG. 7 shows the obtained digit values.
As shown in FIG. 7, the digit value of the sealed container depressurized after the retort sterilization treatment increases according to the pressure before depressurization, and the tendency was more remarkable than that of the above-described reference example. . This seems to be due to the fact that the bulging deformation of the can lid when the retort sterilization treatment was performed remained more clearly than in the above reference example. For this reason, the distinction between a good product having no leak and a defective product having a leak was not always clear.
[0028]
[Conventional example 2]
FIG. 8 is a cross-sectional view of a can lid in which a flat plate portion is directly connected to an annular groove to eliminate an annular bead portion and a concave panel portion is formed in the flat plate portion. The canning sound inspection was performed in the same manner as in Examples 1 and 2. The obtained digit value is shown in FIG.
As shown in FIG. 9, the digit value of the sealed container depressurized after the retort sterilization treatment increased according to the pressure before depressurization when the internal pressure of the can was around 130 KPa or more. This is due to the residual bulging deformation of the can lid during the retort sterilization process, and in the end, it is possible to distinguish good products without leaks from defective products with leaks based on the digit value. Did not.
[0029]
Conventional example 3
This is a can lid in which only an annular groove is formed inside a winding flange portion, a flat plate portion is directly connected to the annular groove, and a concave panel portion is not formed in the flat plate portion. The shape is shown as a sectional view in FIG. The canning sound inspection was performed in the same manner as in Examples 1 and 2. FIG. 11 shows the obtained digit values.
As shown in FIG. 11, the digit value of the sealed container depressurized after the retort sterilization treatment increases according to the pressure before depressurization, and the tendency was more remarkable than that of the above-described reference example. . This seems to be due to the fact that the bulging deformation of the can lid when the retort sterilization treatment was performed remained more clearly than in the above reference example. For this reason, the distinction between a good product having no leak and a defective product having a leak was not always clear.
[0030]
Note that, in the above example, an example is described in which defective products are sorted out due to the occurrence of a leak after the retort sterilization treatment.However, the present invention is not limited to the above specific example, and the internal pressure may be reduced due to other factors. The present invention can be applied to detect a state that is considered to be defective as a product by a tapping sound inspection, such as when the pressure is lowered or when the internal pressure is abnormally high.
[0031]
In addition, the present invention is not limited to the can lid, and the portion to which the impact force is applied for percussion is the bottom portion not provided with a pull tab or the like. Therefore, such a bottom portion is integrated with the body portion. The present invention can also be applied to a container formed in the above. One example is shown in FIG. 12 as a partial sectional view. That is, FIG. 12 shows the shape of the bottom of the seamless can 11, and is a short cylindrical shape that rises in the axial direction of the can body 13 from the inner peripheral side of the grounding rim portion 12 having a substantially arc-shaped cross section where the outside of the can is convex. The seamless can 11 has a flat central panel portion 17 which is provided continuously to the inner wall portion 14 and is continuous from the inner peripheral side of an annular concave portion 15 having an arc-shaped cross section protruding inward through the corner portion 16. . This seamless can 11 is formed from an aluminum plate having a material thickness of 0.1 mm or more and 0.3 mm or less, and has a radius of curvature R of 0.5 mm or more and 1.5 mm or less inside a can at a corner 16 of a can bottom 18. A step h in the axial direction between the panel portion 17 and the annular concave portion 15 is 0.2 mm or more and 3.0 mm or less, and includes an annular bead portion 19 and a center concave panel portion 20 similar to those of the first and second embodiments. I have.
[0032]
As the aluminum plate applied to the two-piece can as shown in FIG. 12, various aluminum plates such as 3004 series, 5550 series and 5081 series aluminum alloys which are usually used for cans are applied. The thickness of the aluminum alloy plate is from 0.1 mm to 0.3 mm.
[0033]
On the other hand, as the surface-treated steel sheet applied to the two-piece can, a cold-rolled steel sheet or one or two kinds of surface treatment such as tin plating, nickel plating, electrolytic chromic acid treatment, chromic acid treatment, etc. Those that have done more than seeds are used. The thickness of the steel sheet is 0.1 mm to 0.24 mm.
[0034]
Further, in the field of cans, the metal plate as described above is used as a main material, and at least one surface (inside of the can) is coated with a resin coating or a protective film formed by laminating a thermoplastic resin film. The metal plate material for cans generally used can be used.
[0035]
【The invention's effect】
As described above, according to the present invention, after increasing the internal pressure of the sealed container, when the internal pressure decreases, the deformation easily returns to the original state, and a good product whose internal pressure is not reduced and a defective product whose internal pressure is reduced are used. There is a clear difference in the acoustic characteristics of the percussion sound inspection, and the percussion aptitude is improved, and as a result, the accuracy of the percussion sound inspection of the sealed container can be improved. Conversely, inconveniences such as excluding non-defective products as defective products can be avoided.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of a can lid according to the present invention.
FIG. 2 is a sectional view showing a state in which the can lid is wound around an open end of a can body.
FIG. 3 is a diagram showing a measurement result of a punching suitability of the can lid.
FIG. 4 is a sectional view showing a shape of a can lid according to a second embodiment of the present invention.
FIG. 5 is a diagram showing the results of measuring the suitability for perforation of the can lid of Example 2.
FIG. 6 is a cross-sectional view showing the shape of a can lid of Conventional Example 1.
FIG. 7 is a diagram showing the results of measuring the suitability for perforation of the can lid of Conventional Example 1.
FIG. 8 is a cross-sectional view showing the shape of a can lid of Conventional Example 2.
FIG. 9 is a diagram showing a measurement result of a punching suitability of a can lid of Conventional Example 2;
FIG. 10 is a cross-sectional view showing the shape of a can lid of Conventional Example 3.
FIG. 11 is a diagram showing a measurement result of a punching suitability of a can lid of Conventional Example 3;
FIG. 12 is a partial sectional view showing an example of the shape of the bottom of a seamless can to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Can lid, 2 ... Flange for fastening, 4 ... Annular groove, 5, 13 ... Can body, 6, 19 ... Annular bead part, 7 ... Flat plate part, 8, 20 ... Concave panel part, 15 ... Annular concave part, 17: Central panel part, 18: Can bottom.

Claims (4)

In a container in which the internal pressure is detected based on the acoustic characteristics of vibration generated by the application of an impact force,
An annular bead portion protruding toward the outer surface is formed at the peripheral edge of the flat plate portion forming the bottom, and a concave panel portion recessed toward the inner surface is formed at the center of the flat plate portion. A container with excellent percussion suitability. The container excellent in percussion suitability according to claim 1, wherein an annular groove depressed on a side to be an inner surface of the container is formed on an outer peripheral side of the annular bead portion. The container according to claim 1 or 2, wherein the concave panel portion has a circular shape. The container excellent in percussion suitability according to claim 2 or 3, wherein the depth of the concave panel portion is smaller than the depth of the annular groove.

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