JPH04270930A - Autogenous pressure display container - Google Patents

Abstract

PURPOSE:To detect the abnormality of internal pressure, that is, the deterioration of content by utilizing the strain due to the internal pressure of a container having high rigidity such as a glass bottle. CONSTITUTION:A part easily deformed by pressure is formed on a part of a container 1 having high rigidity and a diffraction lattice 3 is cut in said part and the strain of the diffraction lattice is detected by a moire interference method. An easily deformable material may be used in the easily deformable part or a part having high rigidity may be thinly molded. Or, a part easy to deform configurationally may be formed, for example, by forming a relatively wide plane like the lid 2 of the container 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rigid container provided with an indicator indicating internal pressure, particularly autogenous pressure.

0002

BACKGROUND OF THE INVENTION Conventionally, the only way to detect outgassing, deterioration, etc. of fruit juice, cola, beer, etc. was to observe the turbidity of the contents from outside the bottle. However, this method cannot be used for opaque containers such as colored bottles or cans. It is convenient to detect sealing failure, deterioration, etc. of elastic containers such as aluminum cans by detecting the internal pressure of the container, particularly the deformation of the container due to changes in the internal pressure. The present inventors have previously confirmed that the deformation of this container, that is, its internal pressure, can be easily detected by providing a diffraction grating on the surface of the container and detecting the distortion of the grating using Moiré interferometry. It was proposed to be used as a means of detecting deterioration, etc. (Patent application No. 1-3066)
No. 70).

0003

However, with the above method, it is extremely difficult to detect the internal pressure and its changes in highly rigid containers such as steel cans and glass bottles. This invention aims to control the internal pressure, especially the autogenous pressure, of highly rigid containers such as glass bottles, from the time the container is filled with contents until the time of shipment, while maintaining the container's sealed state. The aim is to obtain a means that can be easily detected from the outside even after being placed in circulation.

0004

[Means for Solving the Problems] The container of the present invention is characterized in that a part of the highly rigid container is provided with a part that is easily deformed by pressure, and a diffraction grating is provided on the surface of the part that is easily deformed. do. The above-mentioned easily deformable portion can be formed by using a material with low rigidity, by reducing the thickness of the constituent material, or by reducing the geometric rigidity by changing the shape, or by combining these factors. The location can be easily transformed. Specifically, it may be the lid of a container, or it may be a part of the container formed into a thin wall to form a part that is easily deformed.
Alternatively, the shape of a portion of the container may be easily deformed, such as by forming a portion of the side surface of a cylindrical container into a flat plate shape.

[0005]

[Example] Example 1 A metal pipe was attached to the bottom of a glass bottle for fruit juice drinks in a manner that did not affect the shape or rigidity of the glass bottle, and a pressure gauge was used to detect the pressure inside the bottle. After connecting it to a vacuum pump so that the internal pressure of the bottle could be freely controlled, an aluminum cap was tightened to create a test bottle. The diameter of this aluminum cap is 28 mm, the plate thickness is 0.23 mm, and the top surface of the cap has a diameter of 10 m.
The diffraction grating is formed by pressing a transfer tool on which the diffraction grating is engraved over a range of m. The pitch of this diffraction grating is 900 lines/mm. FIG. 1 shows an example of an optical reading device for detecting the distortion of the diffraction grating caused by the internal pressure of the lid of the test bottle described above using Moiré interferometry. In the figure, 1 is a glass bottle, 2 is an aluminum cap, and the diffraction grating 3 is formed on the upper surface of the bottle as described above. 4 is a conical mirror; the beam from the HeNe laser 5 passes through the half mirror 7, is diffracted by the diffraction grating 3, is reflected by the conical mirror 4, and enters the diffraction grating 3 again from the opposite direction; The light returns to the direction of incidence, is reflected by the half mirror 7, and is detected by the CCD camera 6. 8 is a metal pipe, 9 is a pressure gauge, and 10 is a vacuum pump. Attach the bottle 1 to the above reading device, and adjust the negative pressure from 350 mmHg to 450 mm using the vacuum pump 10.
Hg, the resulting moire fringes were photographed with a CCD camera, the pitch of the moire fringes and the number of moire fringes within the field of view were measured, and compared with the internal pressure measured with a pressure gauge, the characteristic curve shown in Figure 2 was obtained. I got it. In the figure, since the reference pressure is 400 mmHg, no interference fringes appear within the field of view in the range A above and below it. The number of interference fringes that appear as the pressure changes upward and downward is represented by a step-like curve in the figure, and the pitch thereof is represented by a hyperbolic curve. As a result,
It was possible to detect a difference in negative pressure of 10 mmHg near the reference value.

Comparative Example 1 A test bottle was manufactured in the same manner as in Example 1 except that the thickness of the aluminum cap was 0.6 mm, and the pitch and pressure of moiré fringes were measured using the optical reading device shown in FIG. Although the internal pressure measured by the meter was compared, the change in the pitch of the moiré fringes was small, and only a difference in negative pressure of 30 mmHg could be detected in the vicinity of the reference value of 400 mmHg.

Example 2 The outer diameter of the bottom surface was 50 mm by injection molding from polystyrene resin.
A truncated conical cup with an outer diameter of 65 mm and a height of 67 mm was manufactured. The wall thickness of the cup is 1.5 throughout
mm, but the wall pressure at the center of the bottom surface within a 20 mm diameter range was 0.9 mm. Furthermore, a diffraction grating with a pitch of 500 lines/mm is formed in this thin portion by a molding method using a mold in which a diffraction grating is carved into the corresponding portion of an injection mold. This container was filled with 8.0 ml of water while finely adjusting the amount of filling to create a minute difference in the head space.
It was filled with water at 0° C. and heat-sealed with a polystyrene lid having a thickness of 1.2 mm. When this container was left to reach room temperature and inspected using an optical system similar to that shown in FIG. 1, it was possible to detect a difference in the degree of vacuum of 10 mmHg caused by a difference in head space as a difference in the pitch of interference fringes.

Comparative Example 2 A cup was produced in the same manner as in Example 2, except that the wall pressure at the center of the bottom was 1.5 mm, the same as the other parts, and filled with water at 80°C. When the system was tested, it was possible to detect only a difference in the degree of vacuum of 80 mmHg from the difference in the pitch of the interference fringes.

Example 3 Except for the absence of the thin walled part in which the diffraction grating is carved in the center of the bottom surface,
A polystyrene resin cup was produced in the same manner as in Example 2. As in Example 2, this container was filled with 80°C water while finely adjusting the filling amount to create a slight difference in head space, and a polypropylene lid with a thickness of 0.05 mm was heat-sealed. . This lid has a pitch of 50
A sticker with a reflection diffraction grating of 0 lines/mm is attached. When this container was left to reach room temperature and inspected using an optical system similar to that shown in FIG. 1, it was possible to detect a difference in the degree of vacuum of 10 mmHg caused by a difference in head space as a difference in the pitch of interference fringes.

Example 4 A can body was formed by welding from a tin plate with a thickness of 0.20 mm, and a bottom cover with a thickness of 0.32 mm and a lid with a thickness of 0.37 mm were tightened to form a can body with a height of 142 mm and an outer diameter. A 66mm container was manufactured. This bottom cover has a spherical shell shape with a radius of 54 mm convex inward, and a diffraction grating is engraved on the center of the outer surface of the bottom cover by a method of pressing a transfer tool engraved with a diffraction grating. The pitch of this diffraction grating is set in advance to be 900 lines/mm when the internal pressure is 5 kgf/cm2. When the temperature of this container is 25℃, the internal pressure is 5kgf/c.
100 aerosol cans were produced by filling the hair styling product stock solution and LPG in accordance with a conventional method and clinching the bubbles so that the volume was 2 m2. In order to detect the distortion of the diffraction grating caused by the autogenous pressure in the bottom lid of the aerosol can mentioned above, the can was attached to an optical inspection device similar to the device shown in Figure 1, and the moiré fringes that occurred at a temperature of 45°C were detected. The pitch of the moiré fringes was measured using a CCD camera, and compared with the internal pressure of the aerosol can measured using a strain gauge pressure transducer, the result was 0.2 kgf/cm.
It was possible to detect the difference in the internal pressure between the two as a difference in the pitch of the interference fringes.

[0011]

[Effects of the Invention] As mentioned above, the container of the present invention has high rigidity, and even if it is difficult to detect distortion due to pressure on the order of autogenous pressure, a part of the container is particularly susceptible to distortion. Since a diffraction grating is carved into the portion, the autogenous pressure can be easily detected using the moiré detection method. Moreover, by detecting only the deviation from the set value, different types of containers can be detected by the same measuring device, so it is possible to detect the difference from the time the container is filled with contents until it is shipped. This has the effect of easily eliminating defective products even in the distribution stage where various products coexist.

[Brief explanation of the drawing]

[Figure 1] Conceptual diagram showing the configuration of the strain detection optical system

[Figure 2] Detected characteristic curve diagram

[Explanation of symbols]

1 Glass bottle 2 Aluminum cap 3 Diffraction grating 4 Conical mirror 5 HeNe laser 6 CCD camera 7 Half mirror 8 Metal pipe 9 Pressure gauge 10 Vacuum pump

Claims (1)

[Scope of Claims] [Claim 1] An autogenous pressure display characterized in that a part of a rigid container is provided with a part that is easily deformed by pressure, and a diffraction grating is provided on the surface of the part that is easily deformed. container【
2. The autogenous pressure indicating container according to claim 1, wherein the easily deformable part is a lid of the container.Claim 3: The easily deformable part is formed by thinly molding a part of the container. 4. The autogenous pressure indicating container according to claim 1, wherein the easily deformable portion is provided by forming a part of the container into a shape that reduces geometric rigidity. The autogenous pressure indicating container according to claim 1, characterized in that