Plastic container

Abstract

 A plastic container comprises a container wall (1) sealed in the circumferential direction as well as a lid (2) provided with a lid flange (5) which is welded all round to the container wall (1). This container wall (1) is provided with an essentially radial collar (4) which both permits a good connection with the lid flange (5) and offers a good gripping point for lifting equipment (10,11).

Description

[0001] The invention relates to a plastic container comprising a container wall sealed in the circumferential direction as well as a lid provided with a lid flange which is welded all round to the container wall.

[0002] Such a plastic container is known from EP-B-343749. The lid used in the latter case projects radially outwards and has a raised edge such that the entire vessel can be raised up by means of a special lifting apparatus ("parrot's beak"), which grips both under the projecting portion of the lid and over the edge. In the raised-up position, the entire container is suspended from the lid which is gripped in this way, which results in the weld between lid and container wall being severely loaded. This weld must, after all, transmit the entire weight of the contents of the container to the lid. The weld is also exposed to intermittent loads such as those which occur, for example, during transportation.

[0003] Such a high load of the weld between lid and container wall can be transmitted in the correct manner only if the local stresses in the weld do not become too great. This means that the weld has to extend over a relatively large surface so that the load to be transmitted can be satisfactorily distributed. In the known container, such a large surface is not easy to achieve, given the small thickness of the container wall. In particular, butt-welded embodiments are disadvantageous in this case.

[0004] The object of the invention is therefore to provide a container of the abovementioned type which does not have said disadvantage. This object is achieved in that the container wall is provided with an essentially radial collar. By choosing a sufficiently large radial dimension for the collar, the desired surface for the weld can be achieved. The collar can, for example, face inwards.

[0005] It is also advantageous for the direction in which the material flowed during shaping of the container wall to coincide with the radial direction of the collar, which enhances the quality of the welded joint.

[0006] A further improvement of the container according to the invention could be achieved if, in addition to an enlargement in the weld surface, a reduction in the load to be transmitted could also be achieved.

[0007] This is because, on the one hand, the weld has to be designed to be very strong and reliable if high loadings are to be transmitted; on the other hand, this is because such a weld remains a weak point in the construction of the container.

[0008] Such a further improvement may be achieved if the collar faces radially outwards and is welded to the lid flange on its side which forms the continuation of the interior surface of the container wall.

[0009] In connection with the raising-up of the container according to the invention, the customary lifting apparatus can again be used, this now, however, gripping under the outwardly facing collar of the actual container wall. This means that the weight of the contents of the container can be transferred to the lifting apparatus via the collar which forms a continuation of the container wall. The welded joint between lid and collar now lies outside the path via which the supporting forces are transferred so that said joint is subject only to pressure during raising-up of the container.

[0010] Owing to the favourable ratio of forces in the weld, the end wall can now also be designed to have a substantially constant thickness in cross-section. The usual relatively thick weld can be omitted, which results in a lower weight and higher quality of the end wall.

[0011] The lid flange can be provided with a circumferential ridge, having a height similar to the thickness of the collar and surrounding the collar. Such a circumferential ridge hides the weld between lid and container wall from view which, in certain cases, makes the external appearance more acceptable to the eye.

[0012] The container wall near the collar may also be constricted so that the collar is inside the container wall in the radial direction. The overall diameter of the container may, in that case, be limited to that of known containers, whilst the improved construction with the collar pointing outwards can still be used. In addition, this embodiment makes it possible to provide a relatively large weld surface between lid flange and collar.

[0013] The container according to the invention can be handled better and more easily during transportation, whilst more rapid manufacture and a lighter-weight product with an improved ratio between volume and external dimensions can also be achieved.

[0014] An illustrative embodiment of a container according to the invention will now be described in greater detail.

[0015] Fig. 1 shows a first embodiment of the container according to the invention.

[0016] Fig. 2 shows a second embodiment of the container according to the invention.

[0017] Fig. 3 shows a third embodiment of the container according to the invention.

[0018] The container illustrated in Fig. 1 comprises a container wall 1 as well as a lid 2 which is welded to the container wall 1 via weld 3. The container wall 1 has a collar 4 facing outwards while the lid 2 has a lid flange 5 which also faces outwards. This lid flange 5 rests on the top of the collar 4, i.e. that portion of collar 4 which forms a continuation of the interior surface 6 of the container wall 1.

[0019] The container wall 1 and the lid 2 are welded together on those sides of collar 4 and lid flange 5 which face each other. Known processes are used for this purpose, which comprise heating the material at the weld 3 and which will not be described in greater detail here.

[0020] The lid 2 has, in a known manner, an upright edge 7. Using a lifting apparatus which is known per se, the container can now be raised up by allowing said apparatus to grip on the underside 9 of the collar 4 and over the upright edge 7 of the lid 2. The supporting force generated by the lifting apparatus is absorbed in the collar 4 from where the reaction forces can be transmitted directly to the container wall 1. This means that the weld 3 is loaded only by pressure through the supporting forces exerted by the lifting apparatus. Weld 3 is therefore, in addition, not exposed to the intermittent tensile loads which occur during transportation of the vessel by means of the lifting apparatus so that there is no risk of said weld 3 failing.

[0021] In the embodiment illustrated in Fig. 2, the lid flange 5 is provided not only with an upright edge 7 but also with a downward-facing circumferential ridge 8. This ridge 8 has a height which approximately corresponds to the thickness of the collar 4. The circumferential ridge 8 therefore covers the collar 4 and also the weld 3. In this embodiment, a visually attractive appearance is achieved since any irregularities which could result from melting between collar 4 and lid flange 5 are no longer visible.

[0022] Fig. 2 also shows, partially, the beaks 10, 11 which belong to a lifting apparatus which is known per se and which is usually referred to as "parrot's beak". The beak 11 grips under the outwardly facing collar 3. The top beak 10 grips inside the upright edge 7. The weld 3 is now not loaded by the tensile forces in the container wall 1 since these are absorbed via the collar 4 by means of the bottom beak 11. The weld 3 is actually compressed by the beaks 10 and 11 but that is not a disadvantageous case of load.

[0023] In the embodiment illustrated in Fig. 3, a container wall 12 is provided which has a collar 13 which faces inwards. By means of a weld 14, this inwardly facing collar is welded to a lid 15 which is also known per se. The weld 14 provides a relatively large joint area between lid 15 and container wall 12 so that the forces from said container wall 12 can be transferred satisfactorily to the lid, particularly to the outwardly projecting edge 16 under which a beak of a lifting apparatus now has to grip.

Claims

1. Plastic container comprising a container wall sealed in the circumferential direction as well as a lid provided with a lid flange which is welded all round to the container wall, characterized in that the container wall is provided with an essentially radial collar.

2. Container according to Claim 1, in which the collar faces radially outwards and, at its side which forms the continuation of the interior surface of the container wall, is welded to the lid flange.

3. Container according to Claim 2, in which the lid flange has a circumferential ridge with a height similar to the thickness of the collar, which circumferential ridge surrounds the collar.

4. Container according to Claim 2 or 3, in which the container wall near the collar is constricted so that the collar is inside the container wall in the radial direction.

5. Container according to Claim 2, 3 or 4, in which the lid flange bears an upright circumferential edge on the side facing away from the container wall.

Drawing