Process and device for the tightness check of a container

Abstract

A container has a tube-like or tubular shell, which is sealed against the surrounding atmosphere and has a weld seam at at least one end. For checking the tightness of the container the internal pressure in an interior space of the container is increased by means of external action and the thereby ensuing deformation of the weld seam is detected. Provisions are made in this connection for the weld seam to be clamped between clamping elements before increasing the internal pressure only in a partial area of its surface, which has a distance from the end of the weld seam facing the interior space.

Claims

1. A process for a tightness check of a container which has a tube-like or tubular shell which is sealed against a surrounding atmosphere and has a weld seam at at least one end, the process comprising: increasing an internal pressure in an interior space of the container by external action and detecting ensuing deformation of the weld seam, wherein the weld seam is clamped between clamping elements before increasing the internal pressure only in a partial area of a surface of the weld seam, the surface having a distance from the end of the weld seam facing an interior space of the container.

2. A process in accordance with claim 1, wherein an entire length of the weld seam is clamped.

3. A process in accordance with claim 2, wherein an end area of the weld seam is clamped, said end area facing away from the interior space.

4. A process in accordance with claim 2, wherein a thickness of the weld seam in a cross section between the clamped partial area and the end of the weld seam facing the interior space is detected by means of at least one sensor device and the thickness is compared with a desired value.

5. A process in accordance with claim 1, wherein an end area of the weld seam is clamped, said end area facing away from the interior space.

6. A process in accordance with claim 5, wherein a thickness of the weld seam in a cross section between the clamped partial area and the end of the weld seam facing the interior space is detected by means of at least one sensor device and the thickness is compared with a desired value.

7. A process in accordance with claim 1, wherein a thickness of the weld seam in a cross section between the clamped partial area and the end of the weld seam facing the interior space is detected by means of at least one sensor device and the thickness is compared with a desired value.

8. A process in accordance with claim 7, wherein a distance measuring device is arranged on opposite sides of the weld seam, respectively.

9. A process in accordance with claim 1, wherein the internal pressure in the interior space of the container is increased by means of squeezing the container by means of an external force of pressure.

10. A process in accordance with claim 1, wherein the internal pressure in the interior space of the container is increased to an absolute value of at least 2 bar.

11. A process in accordance with claim 1, wherein the internal pressure in the interior space of the container is increased for a duration of at least 10 sec.

12. A process in accordance with claim 1, wherein an outer shape of the container before increasing the internal pressure is at least partially detected by means of a sensor optical system and the outer shape of the container is compared with a desired shape.

13. A device for a tightness check of a container, which has a tube-like or tubular shell which is sealed against a surrounding atmosphere and the container has a weld seam at at least one end, the device comprising: a first clamping system, by means of which the weld seam can be clamped in a partial area of a surface of the weld seam; a second clamping system, by means of which an external force of pressure can be applied to the container for increasing an internal pressure in an interior space of the containers; and a sensor device, by means of which a thickness of the weld seam can be detected.

14. A device in accordance with claim 13, wherein the sensor device comprises at least two distance measuring devices, which are arranged on opposite sides of the weld seam.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a cross sectional view through the upper area of a tube, including a weld seam before the beginning of a tightness check;

(3) FIG. 2 is a cross sectional view corresponding to FIG. 1 after clamping the weld seam;

(4) FIG. 3 is a cross sectional view corresponding to FIG. 2 after applying an external force of pressure;

(5) FIG. 4 is a cross sectional view corresponding to FIG. 3 at the beginning of the opening or peeling of the weld seam;

(6) FIG. 5 is a cross sectional view corresponding to FIG. 4 with a weld seam open up to the clamping system; and

(7) FIG. 6 is a cross sectional view corresponding to FIG. 5 in the determination of the seam thickness.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) Referring to the drawings in particular, FIG. 1 shows a cross section of an upper area of a container 10 in the form of a tube, which has a shell 11 consisting of plastic, which encloses an interior space 13, whereby the shell 11 is sealed at its upper end via a weld seam 12 running vertically to the longitudinal extension of the tube 10 and vertically to the plane of the drawing. The weld seam 12 has a height h in the axial longitudinal direction of the tube 10 between its lower end 14 facing the interior space 13 and its upper end 18 facing away from the interior space 13. A product, not shown, for example, a cream is located in the interior space 13 of the tube 10.

(9) In order to check the tube 10 for its tightness, the weld seam 12 is, according to FIG. 2, clamped in its end area 12.1 facing away from the interior space 13 between jaw-like clamping elements 15, which form a first clamping system 19, while applying an external clamping force F.sub.1. It is essential here that a sufficiently free, unclamped area of the weld seam remains between the clamped area 12.1 and the end 14 of the weld seam 12 facing the interior space 13. In the exemplary embodiment shown, the weld seam 12 is clamped over a height k, while a height a of the weld seam 12 remains free, whereby ak. In particular, provisions are made for the height a of the free, unclamped area to be at least twice as large as the height k of the clamped area 12.1, i.e., a2k. As an alternative, however, provisions may also be made for the free height a of the weld seam 12 to be smaller than the height k of the clamped area 12.1, i.e., ak. Preferably: ak2a.

(10) The jaw-like clamping elements 15 are pressed together with the force of pressure F.sub.1 and clamp the area 12.1 of the weld seam 12 and over the entire length of the weld seam vertically to the plane of the drawing with certainty.

(11) In a subsequent process step, which is shown in FIG. 3, an external force of pressure F.sub.2 is applied to the shell 11, defining the interior space 13, of at least two opposite sides by means of an only schematically indicated second clamping system 20, as a result of which the internal pressure in the interior space 13 of the tube 10 is increased to an absolute value of approx. 2 bar. This condition is shown in FIG. 3.

(12) When the weld seam 12 is formed properly and tight, it retains its shape in spite of increasing the internal pressure, as it is shown in dotted line in FIG. 4. When the weld seam 12 is defective, it begins to open or peel at its lower end 14 facing the interior space 13, as it is shown in FIG. 4.

(13) The increase in the internal pressure in the interior space 13 by means of the external force of pressure F.sub.2 is maintained for a relatively long duration of at least 10 sec. and especially 20 sec. This usually leads to the weld seam 12, when it is defective, opening completely up to the area 12.1 clamped between the clamping elements 15, as it is shown in FIG. 5.

(14) For detecting the deformation or the thickness d of the weld seam 12, a sensor device 16 is provided, which according to FIG. 6 has two distance measuring devices 17, especially in the form of laser measuring devices, arranged on opposite sides of the weld seam 12. Each distance measuring device 17 can measure the distance that the wall of the weld seam 12 has to the respective distance measuring device 17. The said distances are designated by b.sub.1 and b.sub.2 in FIG. 6. Since the distance of the distance measuring devices 17 to each other is known, the thickness d of the weld seam 12 that this weld seam has in the cross section measured by the distance measuring devices 17 can be determined in a simple manner. The thickness d of the weld seam 12 is compared with a desired value, and when it is determined that the measured thickness d of the weld seam 12 deviates from the desired value above a preset limit value, the tube is classified as defective and is eliminated in a subsequent step of the process.

(15) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.