GB2078380A

GB2078380A - Testing for container defects

Info

Publication number: GB2078380A
Application number: GB8016367A
Authority: GB
Original assignee: United Glass Ltd
Current assignee: OI Glass Ltd
Priority date: 1980-05-16
Filing date: 1980-05-16
Publication date: 1982-01-06

Abstract

A device and method for testing for defects, e.g. "chips", in the neck surfaces of containers such as glass bottles to be fitted with "crown" caps includes an annular sleeve of e.g. glass-filled nylon (3) having a polished frusto-conical inside surface (10) which tightly contacts the outside surface (11) of the neck of a container (12). The container (12) is charged with a predetermined volume or a constant supply of pressure fluid through a fluid passageway (7, 8, 9), and any diminution of the predetermined volume or constant pressure, due to leakage between the frusto-conical surface (10) and the bottle surface (11), is detected.

Description

SPECIFICATION Testing for container defects This invention relates to the testing of containers, notably but not exclusively glass containers, for defects, and provides a device and method for ascertaining the presence or otherwise of defects on the sealing surfaces of containers.

For optimum sealing effect the sealing surfaces of containers, e.g. glass or plastics containers, should be perfectly smooth and free from surface chips or other irregularities. This is especially the case when the containers in question are to be used for the packaging of carbonated beverages, since any leak age of gas between the sealing surface and the closure cap, or the liner within the cap, will clearly spoil the contents of the container. It has been found that the presence of chips in the sealing surfaces of containers is most marked in those containers which have been sealed by the so-called "crown" caps.

Such caps, which are applied to the filled container by a crimping operation, are normally removed from the container by the use of a bottle opener or by firstly removing a tear-strip formed integrally with the cap. The removal of the crown cap has been observed to scratch or chip the sealing surface of the bottle, so that when such bottles are returned to the filler (for sterilisation and subsequent re-filling) the bottles are imperfect.

Devices are known for detecting chips or scratches on the flat sealing surfaces of containers surround ing the mouths thereof. Such devices comprise a flat pad which is pressed onto the flat sealing surface of the bottle, a source of compressed air to fill the bottle with air under pressure, and a leakage detec tion device for detecting if the air in the bottle escapes between the pad and the flat sealing surface.

Bottles which are sealed using "crown" caps do not have a flat sealing surface but, on the contrary, are sealed on the radius or curved edge between the upper surface of the container neck and the over hang or bead onto which the cap is crimped. It is the object of the present invention to provide a device and a method for testing for chips, scratches or other imperfections in the sealing surfaces of such con tainers.

According to the invention a device for detecting the presence of surface imperfections in the outside surface of the neck portion of a container comprises an annular sleeve having a frusto-conical inside surface at one end adapted to contact the said outside surface; a fluid passage internally of said sleeve and in communication with the inside of said container; and means for detecting the leakage from said container of fluid charged into said container.

The invention also provides a method for detect ing the presence of surface imperfections in the outside surface of the neck portion of a container, comprising (i) contacting said outside surface with a frustoconical portion of the inside surface of an annular sleeve, (ii) charging said container with fluid; and (iii) detecting any loss of said fluid between the said outside surface of the neck portion of the container and the said frusto-conical inside surface of the sleeve.

The frusto-conical inside surface of the sleeve must engage the surface of the container without damaging the latter, and it is preferably polished smooth. The entire sleeve is suitably made from a glass-filled nylon material, which is strong, wearresistant and exhibits a highly polished surface.

The accompanying drawing illustrates diagrammatically a device in accordance with the invention.

The device shown in the drawing, which is a part-sectional elevation of the device seated on the top of a bottle, consists essentially of a body member 1, a retaining collar 2, an annular sleeve 3, and a centering plug 4.

The centering plug 4 is removably attached to the lower end of body member 1, e.g. by means of a screw-thread or a bayonet-joint connection. The lower part of body member 1 is surrounded by the sleeve 3, which is held in position by means of a screw-threaded retaining collar 2 attached to the body member 1. An O-ring seal 5 is positioned between an upper shoulder on sleeve 3 and a shoulder 6 on body member 1. Body member 1 is formed centrally with a fluid passageway 7, which communicates at its lower end with a vent 8, at right-angles to the passageway 7, vent 8 communicating with an annular fluid chamber 9 formed between the sleeve 3 and the lower end of body member 1 by reducing the outside diameter of the body member 1 in that area.

At the lower end of sleeve 3 is formed a frustoconical inside surface 10. This is highly polished and contacts the side sealing surface 11 of a container 12.

(It will be seen that the mouth of the container 12 as shown in the drawing is formed with the standard finish for the receipt of "crown" caps). A source of fluid pressure is, in use, attached to the top of the body member 1, but is not shown in the drawing, for the sake of clarity. Suitably the source of fluid pressure comprises an air-filled cylinder with a reciprocating piston which charges into bottle 12 a predetermined volume of air.

Body member 1 and collar 2 are suitably formed from mild steel. Sleeve 3 and plug 4 are suitably formed from nylon, e.g. a glass-filled nylon material.

In use, the device is lowered onto the top of bottle 12, the centering plug 4 entering the neck of the bottle and ensuring the proper location of the device.

The plug 4 is a loose fit in the neck of the bottle, and the flange 13 of the plug 4 makes no contact with the flat top surface of the bottle. The device is pressed firmly onto the bottle, e.g. under a spring loading of say 101b, so that the surface 10 of the sleeve 3 tightly contacts the surface 11 of the bottle. A known volume of air is then charged from the source of pressure air into the central passageway 7, the vent 8, the annular chamber 9 and the bottle 12. Any diminution in the volume of this air can only come about by leakage of the air between the surfaces 10 and 11, and this will only happen if the surface 11 has chips or scratches formed in it. Therefore, the predetermined volume of air is monitored, to see if it remains substantially constant. If indeed there is a reduction in this volume, it will be assumed that there is in fact an imperfect surface 11, and the bottle 12 can be treated accordingly.

The entire device is suitably mounted for reciprocating movement, which may be under pneumatic control, and may operate at very high speeds, e.g. of the order of 200 cycles per minute.

Although the device specifically described fills the container 12 with a pre-determined volume of air from a cylinder, it is possible to charge the container with a continuous supply of air at a constant pressure and detect any leakage by monitoring the pressure and noting any changes.

Claims

1. A device for detecting the presence of surface imperfections in the outside surface of the neck portion of a container comprising an annular sleeve having a frusto-conical inside surface at one end adapted to contact the said outside surface; a fluid passage internally of said sleeve and in communication with the inside of said container; and means for detecting the leakage from said container offluid charged into said container.

2. A device as claimed in claim 1 wherein said frusto-conical surface is polished smooth.

3. A device as claimed in claim 1 or 2 wherein said annular sleeve is made from a glass-filled Nylon material.

4. A device as claimed in claim 1, substantially as described with reference to the drawing.

5. A method for detecting the presence of surface imperfections in the outside surface of the neck portion of a container, comprising (i) contacting said outside surface with a frustoconical portion of the inside surface of an annular sleeve; (ii) charging said container with fluid; and (iii) detecting any loss of said fluid between the said outside surface of the neck portion of the container and the said frusto-conical inside surface of the sleeve.

6. A method as claimed in claim 5 wherein said container is charged with a predetermined volume of fluid and any reduction in said volume of fluid is detected.

7. A method as claimed in claim 5 wherein the container is charged with a continuous suppiy of fluid at a constant pressure and any change in said pressure is detected.

8. A method as claimed in any of claims 5 to 7 wherein the fluid is air.

9. A method as claimed in claim 5, substantially as described with reference to the drawing.