GB2265330A - Process for manufacturing a plastic container suitable for a hermetically closable lid and a container so obtained - Google Patents

Description

2265330 PROCESS FOR MANUFACTURING A PLASTICS CONTAINER SUITABLE FOR A

HERMETICALLY CLOSABLE LID AND A CONTAINER SO OBTAINED The present invention relates to a process for manufacturing a plastics container and a hermetically closable lid therefor.

More particularly, the invention relates to the technical field of manufacturing a plastics container with its hermetically closed lid by extrusion of the plastics material in viscous state in forming moulds previously conceived and carried out.

It has been proposed to provide a plastics cylindrical container with a projection or a small collar inside the sidewall to engage the rim of the lid inserted by pressure. The proposals have been very laborious. Three such proposals will be briefly described.

A first method consists in moulding a separate plastics ring nut with an inner projection and having a diameter slightly inferior to that of the container mouth, introducing it inside the container under the mouth and welding it by using an annular press at high temperature.

The aforesaid method is very expensive and involves considerable time for the different processings that we have mentioned.

A second method consists in carrying out a mould with respective retractable counter-mould or core allowing the forming of the container cylindrical body and of its inner rim.

To obtain a container of such a make it is necessary to use a very expensive mobile complex mould with variable volume and two subsequent stages or processings are needed with heavy waste of means and of time.

The aforesaid mould in the first phase is in an expanded position in order to form the body of the cylindrical container (allowing the extruded plastics material to penetrate all the cavities of the mobile metal mould) and in a second phase gets narrower to enable the mould to let the container come out.

As mentioned, said method avails itself of a complex and expensive mould, with inner mechanisms for its expansion and contraction, and of prolonged processings with consequent costs outlay.

A third method of manufacturing contai ners with inner projection is based on the opening inside the connecting link or terminal band of the side-surface of the cylindrical container.

Said method needs a normal mould of the container body and a subsequent process of tucking-up of the band provided with a projection inside the container, with a considerable increase of manufacturing costs which has inevitable consequences on the cost of the finished container.

The limits and the inconvenience of all the abovedescribed manufacturing methods of plastics cylindrical containers with projection or inner small collar for the lid insertion are evident.

Against this background, in accordance with the invention, there is provided a process for manufacturing a plastics container and a hermetically closable lid therefore, comprising extruding plastics material in a viscous state from a tank through an outlet aperture to a mould for forming the container, wherein the viscous plastics material is injected at high pressure into the mould for forming--the--c-ontainer,zaid -mould -ha:ving--a--chamber-for the fabrication simultaneously with the container body of reinforcement on the outer wall and of a projection on the inner wall of the container; and wherein from an outlet aperture in the tank the plastics material also reaches a mould for forming the lid for hermetically closing the mouth of the container.

The container is preferably obtained in one moulding operation by means of the mould, said container having in the proximity of the rim of the mouth and externally on the sidewall a multiple reinforcement and internally on the sidewall a profiled projection parallel to the rim of the mouth of the container.

Preferably plastics material is extruded in the moulds for forming the container and the relating lid. said moulds comprising suitable cavities for the simultaneous, but independent, manufacturing of the container body and of the lid, the container-forming mould being provided with means for the creation of a reinforcement on the outer wall and of a projection on the inner wall in proximity of the rim of the mouth of said container, the lid-forming mould being provided with means for the creation of a circular undercut capable of being inserted in the aforesaid inner projection of the container to realise a perfect tight coupling with it.

The invention also extends to the container and its lid both in plastics material and the relating moulds obtaining simultaneously and independently said container and the lid with the invented process.

Examples of the present invention may obviate and exceed all the aforesaid limits, inconveniences and difficulties connected with manufacture of containers with hermetic lid, carrying out a new process of manufacturing a plastics container and the tightly closed lid. conformed in such a way-Ahat the fonmer has a projection on the inner. side-wall and the latter an outer side undercut capable of being inserted in the aforesaid inner projection of the container to form with the same a perfectly tight coupling since in such a way a single body is created.

Advantages which may be obtained from examples of the invention are summarised in the following heads:

1) insertion of the lid on the container body, by pressure on the lid itself, up to the insertion of the circular undercut of the lid in the projection of the inner wall of the container itself. forming in such a way a single body with the container which avoids any leakage of substances from the same; 2) super-position of the roof-shaped flap of the lid over the container mouth rim to form a further safetyseal which secures the absolute impermeability of the unit container-lid; 3) possibility of manufacturing in separated moulds and not simultaneously the container body and the lid; 4) separation of the containers from the lids in the supplies to the single users, during their transport and storage, with easy coupling of the container to the respective lid after f illing of the container, suitable for containing the most varied substances, materials and products to be introduced for the final sealing with the lid; 5) possibility of removing the lid from the container by using a ordinary lever from the final users of the product contained therein, in order to withdraw and use all substance or material or product. - Further features and advantages of examples of the invention will appear from the detailed description which follows, in relation to the drawings of the enclosed sheet, and which show, as an---example -not linitative, a preferred embodiment of the said invention.

Figure 1 of the enclosed sheet is a crosssectional elevational view of the mould f or f orming the container lid connected, together with the extruding cylinder for the plastics material.

Figure 2 is a cross-sectional elevational view of the container-f orming mould communicating with the same extruding cylinder; Figure 3 is an enlarged elevational representation of the particular coupling of the lid with the inner projection of the container for its hermetic sealing; and Figure 4 is an exploded perspective view of the lid and of the container before their coupling.

The Figures show the manufacturing process of the container 6 having the shape of a right cylinder and of the respective circular lid having a diameter equal to that of the bottom 10 obtained by extrusion from the proper tank 1 of the plastics material into their particular forming metal moulds 4 and 19, and show also the finished products. container 6 and lid 21, obtained through this process.

This includes essentially a tank 1 fed through the opening 2 with plastics material as solid pellets or as powder which is heated by a heat source 30 to make the plastics material contained therein change to the viscous state.

The viscous plastics material is pushed out by a piston 31 from the aperture 3 to reach the forming mould 19 of the lid 21, illustrated in Figure 1 and the forming mould 4 of the container 6 illustrated in Figure 2.

The mould 19 has a chamber 20 for forming the circular undercut and the single mould 4 has a chamber 5 for forming the multiple reinforcement 14 and for forming the projection 15 on the inner sidewall 12 in the proximity of the rim 9 of the mouth 8 of the container 6.

The abovementioned container -6- is provided with a circular bottom 10 having some reinforcing ribs 11 and its upright sidewall 7 has an open upper mouth a capable of receiving the lid 21.

The reinforcement 14 is positioned on the outer sidewall 12, whereas the projection 15 is opposed to it on the inner sidewall 13.

The reinforcement 14 consists of a projecting knurl 16 and has a dimple 32 placed on the rim 9 of the mouth 8 of the container 6 for the introduction of the end 34 of the lever 33 for the lifting of the lid 21.

The projection 15 is situated inside the inner sidewall 13 of the container 6 and is followed in the lower part by an undercut 17 and by a groove 18 that carries the projection 15 to the same upright level of the wall 13.

The lid 21 shows an outer upper face 27 and an inner lower face 28 and has a circular undercut 22 and a contiguous upper projection 23 which continues outside so as to form the roof-shaped flap 26 suitable to surround and to overlap the rim 9 of the mouth 8 of the container 6.

The lid 21 presents, below the undercut 22, a projection 24 ending in the lower rim 25 of the lid 21 which delimits the lower face 28 of the same.

The upper face 27 of the lid presents some concentric reinforcing ribs 29.

Particular working operations of the process will now be described as an example only, not limiting the invention.

The plastics material as pellets or as powder is introduced into the cylindrical tank 1 from the supply opening 2.

The heat source 30 heats said tank 1 and makes the plastics material contained therein viscous.

The piston 31 compresses the material pushing it out of the --apertuifin 3 of '-the- tank 1 - extruding it -in- the forming moulds 19 and 4 of the lid 21 and of the container 6.

The viscous plastics material fills the hollow parts of the moulds and in particular:

The chamber 5 of the mould 4 forms the reinforcement 14 and the projection 15 of the container 6. having the shape of a right cylinder; the chamber 20 of the mould 19 forms the undercut of the lid 21.

As regards the operating conditions of the container 6 and of'its lid 21, the way of inserting this one on the rim 9 of the mouth 8 of the container 6 will now besummarised.

The roof-shaped flap 26 of the lid 21 should be positioned over the aforesaid rim 9 and the lid 21 should be pressed down by hand or by a mechanical device toward the bottom 10 of the container so that the projection 24 fits below the projection 15 of the inner sidewall 13 of the container 6.

The positioning of the projection 24 of the lid 21 below the projection 15 of the inner sidewall 13 of the container 6 and the insertion of the projection 22 of the lid 21 into the aforesaid projection 15 of the container 6 form a perfectly tight coupling between the lid 21 and the container 6.

Said coupling remains fixed until an external force, greater than the one which makes it possible to interfere to modify it, in practice by a lever or another simple machine, causing the detaching of the lid 21 from the container 6 irf order to extract and use its contents.

In practice, to separate the abovementioned lid 21 from the container 6 it is enough to introduce the end 34 of a lever 33, for example a normal screwdriver, into the dimple 32-place-d-ove-r---ttre-reinf orcemenC -1-4-in-proximty of the rim 9 of the mouth 8 of the container 6.

of course, bearing in mind the principle of the invention, the exemplary process may and in practice all the details of the same, may however widely vary, as regards what has been described and illustrated, without leaving the sphere of protection of the present industrial invention.

1.

Claims (7)

CLAIMS:

1. A process for manufacturing a plastics container and a hermetically closable lid therefore, comprising extruding plastics material in a viscous state from a tank through an outlet aperture to a mould for forming the container, wherein the viscous plastics material is injected at high pressure into the mould for forming the container, said mould having a chamber for the fabrication simultaneously with the container body of reinforcement on the outer wall and of a projection on the inner wall of the container; and wherein from an outlet aperture in the tank the plastics material also reaches a mould for forming the lid for hermetically closing the mouth of the container.

2. A process as claimed in claim 1, wherein the container is obtained in one moulding operation by means of the mould, said container having in the proximity of the rim of the mouth and externally on the sidewall a multiple reinforcement and internally on the sidewall a profiled projection parallel to the rim of the mouth of the container.

3. A plastics container and a hermetically closable lid therefor, manufactured by the process of claim I or 2, which container is provided on an outer sidewall with a multiple-reinforcement placed in the proximity of the rim of the mouth; and is provided at the level of said reinforcement on the inner sidewall with a profiled projection parallel to the aforesaid rim of the mouth to receive an undercut in the side of the lid.

4. A plastics container and its hermetically closable lid as claimed in claim 3, wherein the lid has an undercut contiguous to an upper projection and to a lower projection, said upper projection continuing sidewise in a circular roof-shaped flap and the lower projection terminating in the rim contiguous to the lower face of the lid.

5. A process for manufacturing a plastics container suitable to receive a hermetically closable lid, comprising extruding plastics material in a viscous state from a tank through an outlet aperture to a mould for forming the container, wherein the viscous plastics material is injected at high pressure into the mould for forming the container, said mould having a chamber for the fabrication simultaneously with the container body of reinforcement on the outer wall and of a projection on the inner wall of the container.

6. A process as claimed in claim 5, wherein the container is obtained in one moulding operation by means of the mould, said container having in the proximity of the rim of the mouth and externally on the sidewall a multiple reinforcement and internally on the sidewall a profiled projection parallel to the rim of the mouth of the container.

7. A plastics container and a hermetically closable lid therfor, substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.