EP0716735A1

EP0716735A1 - Leak-test installation

Info

Publication number: EP0716735A1
Application number: EP95919300A
Authority: EP
Inventors: Martin Lehmann
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-06-06
Filing date: 1995-06-02
Publication date: 1996-06-19
Also published as: JPH09501506A; CH689126A5; WO1995033984A1; AU2520895A

Abstract

The installation proposed for testing containers for leaks by pressure-difference measurement has a rotating table (11) fitted with container-entrainment arms (12, 13) which rotate with the table and a rotating head fitted with container-closure devices (14). The rotating head can be simply replaced as a complete unit to convert the installation to operate with containers of different sizes, while the actual test device remains fixed in place, by virtue of the fact that the test gas is fed in through a rotary leadthrough.

Description

Leakage test systems

The present invention relates to a tightness test system for rigid containers, in particular plastic bottles, in which containers supplied one after the other are tested on a rotating test table within a passage by temporarily closing the opening provided at the head of the container by means of closing devices and the interior of the container to one during the passage actual test device is connected, a gas pressure is built up in the interior of the container, stabilized and subjected to a differential pressure measurement in order to determine a possible leak and to identify a possibly leaked container.

In known test systems of the type described above, the containers are separated before they are transferred to the rotating test table with the co-rotating test device and are removed again after the test has been carried out.

The separation takes place, for example, via a separation screw or conveyor belts running at different speeds, and the entrainment is carried out via so-called stars with drivers adapted to the format of the containers. The actual leak test is based on a differential pressure measurement of a gas temporarily blown into the containers for test purposes and is eg in. , , , described in detail.

The main problem is that the conversion of the test systems to a new format of the container to be tested is extremely complex, due to the fact that the test table, the associated rotating head with locking devices and the also rotating actual test devices form a unit that is only very large Time and with the help of specialists can be adapted to new formats.

Replacing the unit with a unit set up for a different format is practically impossible, particularly because of the actual test equipment for cost reasons (practically amounts to a new system).

The object of the complete invention was to create a leak test system which can be quickly and easily converted to new formats of the test specimens with a reasonable financial outlay.

This object was achieved according to the invention in a test system of the type defined at the outset by the features according to the characterizing part of claim 1.

Special embodiments of the subject matter of the invention are defined in the dependent claims.

Thanks to the solution according to the invention, the system can be converted to a new format very quickly even without the help of specialized specialists by changing the format-dependent Elements are designed as a unit and are interchangeable as such, while the remaining parts are arranged stationary in the system and remain there for each format.

The core of the solution lies in the rotating union between the test table or rotary head and stationary parts of the system, which enables the connection of a built-up gas volume or gas pressure from a rotating to a stationary part.

The invention is explained in more detail below with reference to an embodiment shown in the drawing. It shows:

Figure 1 shows a leak test system according to the invention purely schematically from the front and from above, with two possible interchangeable test table rotation head units, which can be mounted in the frame of the system.

2 shows a vertical section through a test table equipped with a rotary head;

3 shows a view of the device according to FIG. 2 from above;

Fig. 4 shows the frame of a test system with the fixed system parts, i.e. the test table drive, the rotary feedthrough and other stationary parts of the actual test device;

Fig. 5 shows the system of Fig. 4 from above, and Fig. 6 shows a longitudinal section through the core of the invention, ie through the rotary union.

Fig. 1 of the drawing shows purely schematically in two views (front view and top view) of a leak test system 1 with feed and removal conveyor belt 2 or 3 for containers 4 made of plastic.

The system 1 essentially consists of a frame 5, in which the containers to be tested are guided to a test table 6 with driving star 7, temporarily closed during the cycle time on the test table 6 by a rotating sealing device 8 and by means of a gas pressure test (e.g. differential pressure method) during the Throughput time to be checked for leaks.

The measurements are carried out by means of an actual stationary test device accommodated in the control cabinet 9. Leaky containers are automatically rejected after the test system.

As already mentioned, such test methods are known and e.g. in EP-A-0 460 511.

This document is declared an integral part of the present description.

As can be seen from the schematic diagram (Fig. 1), the containers to be tested are conveyed directly to and from the test table 6 by means of the conveyor belt (in other constructions, the containers are separated in front of the test table by means of a turnstile and then fed to the test table leads) . Of course, containers of any dimension made of their own rigid material, such as plastic containers or bottles, can in principle be checked for leaks using a test system of the type shown.

The same actual test device can always be used for this. The drivers and the locking device must be changed or replaced.

Since the closing device and the actual test device also co-rotated with the test table so far (the test data were transmitted electrically to the stationary control), retrofitting was only possible by specially trained specialists and with a relatively large amount of time.

The essence of the present invention now consists in designing the test table with drivers and rotary head (with a locking device) interchangeable as a unit for each format of the test specimens. Such an exchange is very simple and can be carried out very quickly even without the involvement of specialists.

Each test table can e.g. for 4 to 8, preferably 6 receptacles.

2 and 3 of the drawing show such an exchangeable unit 10, with a rotary table 11, drivers 12 and 13, and a number of closing devices 14 for containers 15 to be tested. All of these components are rotatably connected to one another via a hollow shaft 16.

The entire unit can be easily dismantled in the machine frame and exchanged for another unit (different format) by placing it at the bottom of the central hollow shaft 16 is placed on a drive belonging to the machine.

Since the containers to be tested, after they have been tightly closed by means of the closing devices, have to be put under gas pressure and the gas pressure has to be passed on to the actual test device via suitable lines, there is the difficulty with this system of rotating gas lines to the outside of a stationary test device without pressure losses to lead.

This is done by means of a so-called rotary feedthrough 20, as shown in FIG. 4, but in particular in FIG. 6.

4 and 5 show the machine frame with the drive 17, 18 for the test table (not yet attached here), parts of the stationary device are also shown which allow gas to be supplied from the stationary part to the rotating part of the system. These parts remain the same regardless of the size of the test table, i.e. they do not have to be replaced.

6 shows the core of the present invention, namely the rotating union 20:

A central mandrel 21 is provided with longitudinal bores 22, 23, etc., each of which is assigned to one of the closing devices for the openings of the containers to be tested. Each of these bores 22, 23 can also be connected to gas lines for the measurements to be carried out according to the known principle. The upper end of the central dome 21 is connected to the rotating parts on the underside of the test table and, for example via lines which lead through the hollow shaft 16 (FIG. 2), to the various locking devices.

Each longitudinal bore 22, 23 etc. leads radially outwards over a certain length, via a bore 22 ', 23' etc.

The mandrel 21 rotating during operation is surrounded by a number of stationary annular elements 24-28 which are clamped against one another by means of tensioning screws 29.

Each element 24-28 has on the inner wall an annular channel 24 '-28 * open towards the mandrel 21, so that each bore 22', 23 'etc. communicates with one of these annular channels 24' -28 '. Each ring channel 24'-28 'leads to the outside via an associated radial bore 24 "-28", so that each outlet A-E, which is connected to a specific closing device, can be connected to the test device.

Each ring channel 24 '-28' is sealed against the rotating mandrel 21 by suitable ring seals 30, so that unadulterated measurements are guaranteed.

Claims

1. Leakage test systems for rigid containers, in particular plastic bottles, in which successively supplied containers are tested on a rotating test table within a continuous path by temporarily closing the opening provided at the head of the container by means of closing devices and the interior of the container to an actual one Test device is connected, a gas pressure is built up in the interior of the container, stabilized and subjected to a differential pressure measurement via the closing device in order to determine a possibly existing leak and to separate out a possibly leaky container, characterized in that the rotating driven test table adapted to the format of the containers to be tested also Carriers and the closing device for a number of teeth arranged above the test table and connected to the table via a central hollow shaft l of the rotary head carrying containers is arranged interchangeably as a whole, while the actual test device with differential pressure measuring device is arranged separately in a stationary manner, each individual sealing device leading via rotating lines and a rotary leadthrough into an intermediate chamber of a stationary element and from this individually to the testing device.

2. System according to claim 1, characterized in that the rotary feedthrough has a cylindrical mandrel projecting downward from the underside of the test table, which mandrel corresponds to the number of closing devices Number of longitudinal bores is provided, which open out laterally at a mutual longitudinal distance and each open into an inner ring channel of the stationary elements surrounding the mandrel, which ring channels lead individually to the test device via lines.

3. Plant according to claim 1 and 2, characterized in that a number of the closing devices corresponding number of annular stationary elements are mounted in a row on the rotating mandrel, these elements are preferably clamped together via a plurality of lag screws.

4. Plant according to claim 3, characterized in that the inner ring channel of each stationary element along both channel edges are sealed by means of sealing rings against the mandrel.

5. Plant according to at least one of claims 1-4, characterized in that the closing device for each individual container via lines leading through the hollow shaft under the test table lead into a mandrel rotatably connected to the hollow shaft, in which a longitudinal channel is provided for each supply line These channels open outward at intervals into an inner ring channel of an annular stationary element seated on the mandrel, which ring channels lead outwards through a bore.

6. Plant according to at least one of claims 1-5, characterized in that the feeding of the containers to be tested takes place by a transport path leading directly to the test table and that the separation takes place by the drivers of the test table.