OPEN HEAD PLASTIC DRUM AND MANUFACTURING METHOD

Abstract: An open head plastic drum, which can be closed by means of a removable lid (5), comprises a drum body (1) and a bottom end (2) connected thereto or formed therewith, which drum body has an upper edge onto which the lid can be sealingly connected. The upper edge comprises an outwardly curled bead flange (3) which is a continuation of the drum body.

Description: Open head plastic drum and manufacturing method The invention is related to an open head plastic drum which can be closed by means of a removable lid, which drum comprises a drum body and a bottom end connected thereto, which drum body has an upper edge onto which the lid can be sealingly connected. The body and bottom end may be connected by welding or glueing. Also, it is possible to form them as a unity by blow moulding. Such drums are generally known. They are used for packaging various products; due to the fact that the lid can be removed, filling and emptying of the drum can be carried out rather quickly. Also, materials which are less flowable, solid or viscous materials can be handled with such drums. The drum body usually has a flange near its open end which may be formed by pressing the material in the mould, for example with a preformed slide. Said flange provides a connecting means onto which the lid can be connected. The lid which is thus connected to the drum body enables handling with handling equipment and provides, together with the drum body, the drum with the necessary strength and stiffness with respect to external forces. In particular, it provides resistance against deformations of the drum when it topples or drops and hits the ground at the location of said flange. Thereby, the deformations are kept within limits, preventing the container from leaking. Most existing open head plastic drum bodies have an upper flange with sharp edges on the outside of the drum and irregularities, caused by cutting off the tops, on the inside of the drum as well as an opening diameter which is considerably smaller than the maximum drum body diameter. This may lead to problems such as difficulties in handling and emptying the drum, cleaning and reconditioning the drum (danger for contamination) etc. In particular, frozen or very viscous contents may get stuck during emptying. Sometimes it is difficult to see whether contaminations still remain after cleaning. Furthermore, the irregularities may comprise sharp edges of plastic material which make the empty drum difficult to handle by hand (operators may cut themselves easily). The object of the invention is to provide an open head plastic drum which lacks these problems and provides easy handling, filling, emptying and reconditioning, and can be used in follower plate applications where drums are emptied using a press. This object is achieved in that the upper edge comprises an outwardly curled bead flange which is a continuation of the drum body. Said outwardly curled bead flange forms a unity with the drum body. The outwardly curled bead flange of the drum according to the invention provides the open head drum with a relatively high stiffness, which makes the drum, even without lid, retain its shape which simplifies handling and filling. Moreover, such bead flange would still provide the necessary reinforcement particularly in case the wall of the drum body is relatively thin. This has the advantage that the drum may be carried out lighter from a smaller amount of plastic material . Furthermore, the drum body may have an essentially cylindrical shape, which is favourable for ensuring a better eptyability, particularly in case of very viscous or frozen contents. From DE-A-3908099, a traditional open head drum is known. The figures and description of said publication disclose a specific embodiment with a steel bead flange, onto which a lid is connected by means of a clamping ring. Although DE-A-3908099 mentions that the drum may consist of plastic, no specific example of an open head plastic drum is shown, nor a plastic bead flange The drum body may be manufactured in several ways. One embodiment comprises a drum body made by tube extrusion, whereby the drum body consists of an extruded tube, the extruded diameter of the said tube being equal to the nominal diameter of the drum body. Due to the fact that the tube part which forms the drum body has been cut at both its end faces, they have a flat regular shape which makes the forming of a regular bead flange easy. At its outer perimeter the lid preferably has a connecting groove which fits over the bead flange. Said lid may have an outer part surrounding the bead flange. In case the outer ring part, in axial direction of the drum body, covers the bead flange only partly, the lid can be mounted and removed easily. The outer ring part can be gripped after removing the clamping ring, so as to remove the lid without great difficulty. Furthermore, such lay-out enables a firm connecting between the lid and the drum body. The clamping ring directly rests against the bead flange, at the underside thereof. This is made possible by the relatively low outer ring part, which leaves free the lower region of the bead flange for said engagement with the clamping ring. The lid may have a gripping groove lying inwardly and directed opposite with respect to the connecting groove, which gripping groove can be engaged by a beak of a lifting tool. The stiffness and strength of the lid, in particular against impact loads such as occur when the drum hits the ground after toppling over, can be improved by means of a centre portion lying inwardly with respect to the gripping groove. In this respect, the lid may also have, at its inner surface, a reinforcement ring which adjoins the connecting groove, and a second reinforcement ring lying inwardly with respect to the first reinforcement ring. The connecting groove contains a seal or gasket which can sealingly engage the bead flange. This seal or gasket may be a length of elastic material, such as EPDM sponge rubber, which is pressed into said connecting groove. Also, the seal or gasket may be formed by pouring or spraying a solidifying sealing material into the connecting groove. The lid can be clamped onto the bead flange by means of a clamping ring which embraces the outer perimeter of the lid and the bead flange. The clamping ring embraces the outer perimeter of the lid and the bead flange. Said clamping ring preferably has a skirt portion which extends under the bead flange. This skirt portion may act as a stop for the lower beak of the li . fting tool. Thus, the beak is prevented from penetrating and damaging the plastic wall of the drum body. The invention is furthermore related to a method for manufacturing a drum body for a drum according to any of the preceding claims, comprising the steps of: -providing a tube by means of extrusion, -heating an end region of said tube, -forming a bead flange by pressing the end region into a forming die and thereby curling said region outwardly, so as to obtain the drum body. The drum body provided in this method may be manufactured in several ways known per se, such as blow moulding with lost head, double blow moulding, extruded tube with glued or welded bottom end, injection moulding, compression moulding etc. The invention will be explained further with reference to an embodiment of a plastic drum as shown in the figures. Figure 1 shows a drum in cross-section along its axis. Figure 2 shows an enlarged detail of figure 1. Figure 3 shows a detail of the drum bead flange region. Figure 4 shows a second embodiment. The plastic drum as shown in figures 1 and the enlarged detail of figure 2 has a drum body 1 onto which a bottom end 2 is connected, e.g. by welding or glueing. The upper edge of the drum body 1 has an outwardly curled bead flange 3, which forms a unity with the wall of the drum body 1. The drum body 1 is almost or essentially cylindrical, but its upper region may have a somewhat narrower part 4 which however is small so as not to disturb the generally cylindrical shape. Said narrower part may result from the forming operation for obtaining the bead flange 3. Due to this almost cylindrical shape, the drum can be easily emptied, even in case the contents are frozen or are very viscous, such as jam- or jellylike products. The open end of the drum is closed by means of a lid 5, which is clamped onto the bead flange 3 by means of a clamping ring 6, known per se. The lid 5 has a middle piece 7, which is surrounded by a circumferential gripping groove 8. The middle piece 7 also may have one or more bung holes 9, the closing plug being omitted for clarity. The middle piece may also be flat. Diametrically outside with respect to the gripping groove 8, a connecting groove 10 is available which carries a sealing member 11. The connecting groove 10 with sealing member 11 can be placed on top of the bead flange 3, so as to obtain the desired tightness of the closed drum. The clamping ring 6 has a U-shaped cross-section, which on the one hand grips over the edge part 12 which defines the connecting groove 11, and which on the other hand grips underneath the bead flange 3. The clamping ring can be made from different materials such as metal or plastic. The clamping ring 6 can be clamped tightly onto these elements by means of a clamping device, such as a bolted connection in the ring, or a clamping lever, known per se. Furthermore, the clamping ring has an integral, downwardly extending skirt 13, which lies against the upper part of the drum wall 1. Upon lifting the drum, the lower beak of a lifting tool is placed underneath the clamping ring and against the skirt 13, and the upper beak is situated in the gripping groove 8. Thereby, a safe gripping operation can be carried out. The lower bead flange cannot penetrate into the upper part of drum body 1. due to the fact that it rests against the (metal or plastic) skirt of the clamping ring 6. The tightness of the closed drum should be guaranteed under extreme impact conditions, such as defined by toppling of the drum. When the drum topples or is dropped, the clamping ring 6 hits the ground, and the shock caused thereby pushes the upper part of the drum body 1, and the lid 5 inwardly. If these deformations become too large, the sealing effect of the gasket 11 may get lost. In order to provide the desired stiffness of the closed drum with respect to such impact loads, circular ribs 14 and 15 have been applied on the inner side of the lid 5. Together, the bead flange 3 on the upper part of the drum body, and these ribs 14, 15 provide a desired stiffness against forces which act on the upper end of the drum body and on the lid 5, and assist in maintaining the shape of these parts under different types of loads such that the. sealing action of gasket 11 can be maintained. Furthermore, the drum may have various embodiments. For instance, a liner could be provided on the inside. Also, other types of closures are possible, such as a large concentric closure in the centre of the dome. By cutting off the head of a tight head drum, and subsequently forming a bead flange at the drum body edge thus obtained, a conversion from tight head to open head drum is possible. In the embodiment of figure 4, a reinforcing ring 23 has been applied within the bead 24. The contents of the drum can also be removed by means of a pressing plate, which is pressed into the open head top. The pressing plate has a hole to which a tube is connected for conveying the contents out of the drum upon pressing the pressing plate into the drum.

Claims: C l a i ms 1. Open head plastic drum which can be closed by means of a removable lid (5), which drum comprises a drum body (1) and a bottom end (2) connected thereto or formed therewith, which drum body (1) has an upper edge onto which the lid (5) can be sealingly connected, characterised in that the upper edge comprises an outwardly curled bead flange (3) which is a continuation of the drum body (1). 2. Drum according to claim 1, wherein the drum body (1) is essentially cylindrical. 3. Drum according to claim 1 or 2, wherein the bead flange (3) has an end face which is near to, or touches, the outer surface of the drum body (1). 4. Drum according to claim 3, wherein the bead flange (3) is curled over more than 270°. 5. Drum according to any of the preceding claims, wherein the drum body (1) consists of an extruded tube, the extruded diameter of the said tube being essentially equal to the nominal diameter of the drum body. 6. Drum according to any of the preceding claims, wherein the lid (5) at its outer perimeter has a connecting groove (10) which fits over the bead flange (3). 7. Drum according to any of the preceding claims, wherein the lid (5) has an outer ring part (12) surrounding the bead flange (3). 8. Drum according to claim 7, wherein the outer ring part (12), in axial direction of the drum body, covers the bead flange (3) only partly, while the connecting groove (10) fits over said flange (3). 9. Drum according to any of the preceding claims, wherein the lid (5) has a gripping groove (8) lying inwardly and directed opposite with respect to the connecting groove (10), which gripping groove (8) can be engaged by the upper beak of a lifting tool. 10. Drum according to claim 9, wherein the lid has a dome shaped middle portion (7) lying inwardly with respect to the gripping groove (8). 11. Drum according to any of claim 6-10, wherein the lid (5) at its inner surface has a reinforcement ring (14) which adjoins the connecting groove (10). 12. Drum according to claim 11, wherein the lid (5) has a second reinforcement ring (15) lying inwardly with respect to the first reinforcement ring (14). 13. Drum according to claim 12, wherein the reinforcements rings (14, 15) are opposite the gripping groove (8). 14. Drum according to any of claims 6-13, wherein the connecting groove (10) contains a seal (11) which can sealingly engage the bead flange (3). 15. Drum according to any of claims 6-14, wherein the lid (5) can be clamped onto the bead flange by means of a clamping ring (6) which embraces the outer perimeter of the lid (5) and the bead flange (3). 16. Drum according to claim 15,. wherein the clamping ring (6) surrounds the outer ring part (12) of the lid (5) and contacts the lower region of the bead flange (3). 17. Drum according to claim 15 or 16, wherein the clamping ring (6) has a skirt portion (13) which extends under the bead flange as a stop for the lower beak of the lifting tool. 18. Drum according to any of the preceding claims, wherein the lid (5) has at least one bung hole (9). 19. Drum according to any of the preceding claims, wherein a reinforcing ring (23) is situated within the bead (24). 20. Drum according to any of the preceding claims, wherein the outwardly curled bead flange (3) forms a unity with the drum body (1). 21. Method for manufacturing a drum body for a drum according to any of the preceding claims, comprising the steps of: -providing a tube by means of extrusion, -heating an end region of said tube, -forming a bead flange by pressing the end region into a forming die, and thereby curling said region outwardly so as to obtain the drum body.

Inventors: VAN KEIMPEMA GERRIT JAN, WENTZEL PETER JURGEN MACHIEL, VAN KEIMPEMA, GERRIT, JAN, WENTZEL, PETER, JURGEN, MACHIEL
Applicants: KEIMPEMA GERRIT JAN VAN, LEER KONINKLIJKE EMBALLAGE, WENTZEL PETER JURGEN MACHIEL, KONINKLIJKE EMBALLAGE INDUSTRIE VAN LEER N.V., VAN KEIMPEMA, GERRIT, JAN, WENTZEL, PETER, JURGEN, MACHIEL
Application year: 1998
Main classification: B65D8
IPC codes: B29C57, B65D8, B65D43, B65D45, B65D47