GB2171046A

GB2171046A - Containers

Info

Publication number: GB2171046A
Application number: GB08503728A
Authority: GB
Inventors: Ath Roderick Michael De
Original assignee: Metal Box PLC
Current assignee: Crown Packaging UK Ltd
Priority date: 1985-02-14
Filing date: 1985-02-14
Publication date: 1986-08-20
Also published as: GB2171048B; GB8602710D0; GB2171048A; GB8503728D0

Abstract

Containers having a tubular body 2 of metal or fibrous material comprise an annular portion 6 extending laterally from the tubular body into a moulding of plastics material which may be a collar, an end wall or a lid. The containers are made by clamping a peripheral margin of the annular portion 6, adjacent the tubular part of the body 2, between a tapered surface 26 of mandrel 10 and a tapered surface 25 of a die member 11 and injection moulding plastics material onto the annular portion. <IMAGE>

Description

SPECIFICATION Containers This invention relates to containers having a tubular body terminating at one end in a moulding of plastics material, a method of making such containers and apparatus for carrying out the method.

British Patent 1,275,051 describes containers having a tubular body of fibrous material onto one end of which a moulding of plastics material is moulded directly to embed the end of the tubular body in the plastics material.

During manufacture of the containers, a mandrel is inserted into the tubular body so that an end wall of the mandrel acts as one wall of a mould cavity. The end of the tubular body and mandrel are inserted into a mould defining a mould cavity spaced around the end of the tubular body. A front member of the mould seals against the cylindrical exterior of the tubular body. Injection of a plastics material, such as polyethylene or polypropylene, forms a moulded end wall directly onto the extremity of the tubular body. It is written that the mould is constructed so that it can be removed from the formed moulding but no details are given as to how this is achieved.

The flared surface of the mould surrounding the tubular body invites supposition that the moulded rim of the component is jumped out of the mould. However slackness of fit to permit jumping out may bring the problem that injection moulding pressures may force the tubular body out of the front member mould before the moulding is completely formed.

In order to overcome this problem this invention teaches use of a tubular body having an annular portion which extends laterally of the rest of the body to permit a peripheral margin of the annular portion to be clamped by relative motion as between co-operating surfaces of a mandrel inside and a die member outside the tubular body while plastics material is moulded onto the free extremity of the annular portion.

Accordingly in a first aspect this invention provides a container having a tubular body terminating at one end in a moulding of plastics material characterised in that an annular portion of the tubular body extends laterally of the rest of the tubular body and into the plastics moulding.

In one embodiment of the container the annular portion extends inwardly and axially from the rest of the tubular body to define a shoulder portion of internal diameter less than the diameter of the rest of the tubular body.

In another embodiment of the container the annular portion comprises a shoulder portion supporting an outwardly flaring flange of maximum diameter less than that of the rest of the tubular body.

In both embodiments the shoulder portion may be a frustrum of a hollow cone. The included angle of the included angle of the frustrum may be in the range between 600 and 900 so that shoulder is strong enough to support a stack of like containers. However other included angles may be used.

The tubular body may be of a fibrous material, such as a paperboard, or a plastics material. If the fibrous body has an interior lining of a plastics material it is advantageous for the moulding to be fused to the plastics lining as is also convenient if the body is made of plastics material.

If the tubular body is made from a sheet or flat blank held in tubular shape by a side seam, such as a lap joint, the moulding is able to conform to the uneven joint and present a smooth sealing surface to a closure. This arrangement is particularly advantageous for use on metal tubular bodies.

In a second aspect this invention provides a method of forming a container having a tubular body terminating at one end in a moulding of plastics material characterised by the steps of providing a tubular body having at one end an annular portion extending laterally of the rest of the tubular body; clamping the annular portion between a mandrel inside the tubular body and a die member outside the body so that the terminal margin of the annular portion is in a mould cavity defined by said mandrel and die; and injecting a plastics material into the die cavity to form a moulding of plastics material on the terminal margin of the annular portion.

In one embodiment of the method the annular portion is bent toward the axis of the tubular body to define a shoulder portion having a terminal edge of girth less than the girth of the tubular body.

In another embodiment of the method the annular portion comprises a shoulder portion which supports an outwardly flaring flange of maximum girth less than the girth of the tubular body.

The shoulder portion may be a frustrum of a hollow cone. The included angle of the hollow cone is preferably in the range of between 600 and 900.

The annular portion of the tubular body may be formed to match a taper on the mandrel and die member by the action of clamping between mandrel and die member. Alternatively the annular portion may be formed in a preliminary operation prior to insertion in the die member of the mould.

The tubular body may be made of a plastics material, or altertnatively a composite of a fibrous material and an interior lining of a plastics material to which the moulding is fused during injection moulding.

Alternatively the tubular body is made from a flat blank held in tubular form by a side seam. For example a rectangular metal blank held in tubular form by a lap weld in which case the plastics moulding seals against the uneven lap.

In a third aspect this invention provides apparatus for forming a container having a tubular body terminating at one end in a moulding of plastics material characterised by a mandrel enterable into the tubular body, a die member outside the tubular body adapted to co-operate with the mandrel to clamp an annular portion of of the tubular body extending laterally of the tubular body; said mandrel, die member and a die defining a mould cavity surrounding the free edge of the annular portion, and means through which a plastics material may be injected into the mould cavity to form a moulding of plastics material on the annular portion.

In one embodiment of the apparatus a flared entry to the die member co-operates with a matching tapered surface on the mandrel to clamp a like flared annular portion of the tubu lar wall .

The flared entry to the die member, tapered surface of the mandrel and annular portion of tubular wall may each be frustoconical. The included angle of the frustoconical die member, tapered surface and annular portion are preferably each within the range between 600 and 90. Stop blocks may be provided to limit the clamping pressure exerted by mandrel and die member on the annular portion to protect a fibrous body.

One advantage arising from the clamping of the annular portion of the tubular body between the mandrel and die member is that the clamping pressure prevents leakage of flash which would make the container unsightly.

Another advantage arising from use of relative motion as between the mandrel and die member in a direction parallel to the axis of the container to clamp a peripheral margin of the annular portion is that reverse of the motion releases the finished moulding without recourse to "jumping out" or split tooling.

Various embodiments will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a perspective view of a container with lid; Figure 2 is a side view of the container of Fig. 1 sectioned on a diameter; Figure 3 is a cross sectioned view of tools for moulding a ring around a tubular body.

Figure 4 is an enlarged fragmentary view of modified tooling showing the position of clamping; Figure 5 is a side view, sectioned on a diameter, of a container having a moulded ring fused to an interior lining.

Figure 6 is a like view to Fig. 5 of a container having a ring moulded to embed a flange in it; Figure 7 is a like view to Fig. 5 of a container having ring and lid moulded in one piece; Figure 8 is a like view of a container having a shoulder, the free edge of which is embedded in a moulded ring with screw threads retaining a cap; Figure 9 is a like view of a container having an outwardly directed flange embedded in a moulded ring suitable for an overcap; Figure 10 is a fragmentary view of a container with overcap; Figure 11 is a fragmentary view of a metal container with plastics rim; and Figure 12 is a diagramatic representation of apparatus for operating the tooling of Fig. 3 or Fig. 4.

In Fig. 1 a finished container comprises a metal bottom wall joined by a double seam 1 to a tubular body 2 of fibrous material having at the other end a collar 3 of plastics material moulded around the rim 4. A plug lid 5, of plastics material fits within the rim.

Fig. 2 shows that the collar of plastics material is supported by an annular portion of the tubular body comprising a shoulder 6 which supports an outwardly directed flange 7. The shoulder portion is in the form of a frustrum of a hollow cone of included angle substantially 900. It is desirable to have a fairly steep slope on the shoulder so that the conical shape is able to support the top load arising during lidding and subsequent stacking of filled containers. The shoulder depicted in the tooling of Fig. 4 has an included angle of 600.

Fig. 3 shows diagramatically apparatus for moulding the collar 3 into the body 2: the apparatus is depicted during clamping of the shoulder portion 6 between a mandrel 10 and a die member 11 before plastics material is moulded onto the shoulder 6 and flange 7.

In Fig. 3 the apparatus comprises a top tool 12 and a die assembly 13 beneath. The top tool comprises a top tool holder 14 to which the mandrel 10 is fixed by studs such as that denoted 15, a thrust plate 24 and stop blocks 16 arranged to each side of the mandrel. The die assembly 13 comprises the die member 11 having a flared entry, a die bed 17 supporting the die member 11, and an ejector plug 18 resiliently supported by springs 19 in the die bed 17 from which extends a central rod 20 which passes through the ejector plug 18 to co-operate with a bore 21 in the mandrel 10 to hold the mandrel central in relation to the die member 11. Guide pillars, such as that denoted 22 extend from the die bed 17 through the die member 11 to pass up into the top tool holder 14 to give controlled guidance to the top tool 14 as it is moved towards and away from the die assembly 13 by a press (not shown).

A delivery passage 23 is defined by recesses in the lower face of the die member 11 and upper face of the die bed 17. The delivery passage 23 reduces in cross section near the entry to the moulding cavity so that the feeder sprue can be broken away from the moulding.

In one method of operating the apparatus the top tool 12 is raised about the die assembly 13 and a tubular body with prefor shoulder 6 and flange 7 is placed on the drel 10 with the flared shoulder on a tape surface 25 of the mandrel 10 (best seen Fig. 4).

The top tool 12 is lowered so that the tapered surface 25 of the mandrel 10 clamps the flared shoulder 6 against the tapered surface 26 of the die member 11 to firmly close a mould cavity defined by the die member, part of the die bed and the shoulder 6 and flange 7 of the tubular body 2.

Excessive clamping pressure, which might crush a spirally wound composite material of the tubular body, is prevented by the stop blocks 16 abutting the face of the die member 11. When the tubular body is made of metal the stop blocks 16 are not essential.

in Fig. 4 the zone in which the clamping pressure is exerted is indicated by arrows. In Fig. 4 the tapered surface 26 of the die member 11 and the tapered surface 25 of the mandrel are inclined at 600 to the central axis of the tubular body or cylindrical surface of the mandrel 10. This corresponds to an included cone angle of 600. In Fig. 3 the incline tion of tapers 25, 26 to the cylindrical surface of the mandrel 10 is 450 corresponding to an included cone angle of 900 which matches the included cone angle of the shoulder portion 6.

While the shoulder 6 is clamped between the mandrel 10 and die member 11 a plastics material is injected to fill the mould cavity and form a collar of plastics material around the shoulder 6 and flange 7. Suitable plastics materials include polyethylene, polypropylene or nylon.

After a period of time, to allow solidification of the collar, the top tool 12 is raised away from the die assembly 13 so that the ejector plug 18 is raised by pressure from spring 19 to force the moulded collar 3 and tubular body 2 out of the member 11, and whilst so doing breaks the plastics 'gate' of the delivery passage 23. The tubular body with collar is then removed from the apparatus which is ready for another work cycle. Other known runner and gating systems may be used if preferred.

In an alternative method of using the apparatus of Fig. 3 a cylindrical tubular body (not shown) is placed on the mandrel 10 with one end abutting the thrust plate 24. The top tool is then lowered so that the other end of the tubular body is forced by the thrust plate 24 into the tapered surface 26 of the die member which sweeps the free edge of the tubular body towards the tapered surface 25 of the mandrel 10 where it is clamped. Injection moulding then proceeds as already described.

This alternative method may be used to form annular portions extending laterally of the tubular body which will be described later. Any risk that the annular portion so made has localised wrinkles is not detrimental because they will be embedded in plastics material which defines sealing surface for a cap or other closure. For example the embodiments of Figs. 8 and 9 could be made this way.

Fig. 5 shows an alternative form of the collars of Figs. 1 to 4. In Fig. 5 the tubular body 32 has an interior lining of plastics material which extends over the shoulder 6 and flange 7. A rim moulding 34 extends over the exterior surfaces of shoulder 6 and flange 7 to cover the free edge and fuse with the interior lining 33. This arrangement of rim moulding seals the edge of the fibrous body material so providing a container suitable for fluids which may be poured from the container.

Fig. 6 shows a container similar to that of Fig. 5 except that the rim moulding 35 extends into the interior of the container to define a receiving surface 36 for a plug lid. An advantage of this arrangement is that the material of the receiving surface protects the lining material from abrasion when the lid is removed or replaced.

Fig. 7 shows that the invention may be used to provide an end wall for the container.

In Fig. 7 the end wall 36 is in the form of a combined collar 37 and plug lid 38 joined by an annulus 39 of reduced thickness. The lid is removed from the collar by tearing the annulus of reduced thickness after which the lid and collar function as do the lid and collar of Fig.

2. However care must be taken to chose a lining material and lid materials which do not fuse together. For example an aluminium foil lining and a low density polyethylene moulding. If however an hermetic primary seal is required the exterior surface of the flange and shoulder may be provided with a coating to which the moulded plastics material will adhere.

Fig. 8 shows a tubular body 40 terminating in an annular portion in the form of a frustoconical shoulder portion 41. The shoulder portion 41 is embedded in a rim 42 of plastics material which extends into keyed engagement with the lining 43 inside the body. The exterior surface of the rim is provided with a plurality of inclined outwardly projecting beads 44 which serve as screw threads to co-operate with complementary beads 45 on the interior of a skirt 46 of a screw cap 47.

Fig. 9 shows a tubular body 50 terminating at one end in an outwardly directed flange 51 which is embedded in a rim 52 of plastics material. Such a rim may be profiled to receive a snap fit overcap (not shown) such as is shown in Fig. 10 on a container of the kind shown in Fig. 5.

An advantage of the container of Fig. 10 is that the shoulder 6 and flange 7 support the collar 34 in board of the rest of the tubular body 32 so that the curled skirt 55 of over cap 56 does not project laterally beyond the tubular body. This neat arrangement enables the containers to be arranged close together for economy of space.

Whilst the invention is particularly useful for reinforcing the rim of tubular bodies of fibrous materials it is not limited thereto.

Fig. 11 shows a tubular body made from a rectangular body blank of sheet metal, such as tinplate or aluminium, which is held in tubular shape by a side seam. The seam may be a lap joint created by welding, soldering or adhesion. In each case the metal thickness creates a step in the metal rim surface which is a potential leakage path past a closure fitted in such a metal rim. In Fig. 11 the tubular body 60 has a shoulder 6 and flange 7 embedded in a rim of plastics material comprising an outer collar 63, a sealing surface 64 and an inner surface 65. The rim therefore seals the potential leakage crevice at the lap joint 66 and provides a strengthened rim to the metal flange. Various alternative lid receiving profiles may be moulded on the rim to receive closures of the kinds already described.

Fig. 12 shows apparatus for operating the tools of Fig. 3 or Fig. 4. The apparatus comprises a press 70 with collating and infeed means 71 to the left and removal means 72 to the right. In the press the so called top tool of Fig. 3 supporting the mandrel 10, is in the lower part of the press and the die assembly is supported adjacent the feed of plastics material in the upper part of the press.

The mandrels 10 are raised to the die assembly for moulding.

The collating and infeed means comprise a rotatable turntable 73 having two arrays of prongs 74 on the under side and a tool block 76 with an array of mandrels 10 therein. The turntable 73 may be raised and lowered on a pillar 75 so that when in use an array of tubular bodies 2 is placed on the prongs 74.

The turntable 73 is then rotated to align with the array of mandrels 10 in the tool block 76.

Lowering of the turntable 73 places each tubular body on a mandrel. The turntable 73 is then raised clear of the tool block which is moved into the press 70.

After moulding, as described already with reference to Figs. 3 and 4, the tool block 76 is moved out of the press to be located under the removal means which is a turntable 77 having means to lift the bodies with mouldings from the mandrels 10 and by rotation of the turntable 77 put the array of containers in a convenient position for removal.

Whilst the containers described are round the invention may usefully be applied to tubular bodies of other cross section such as rectilinear or polygonal peripheral shape.

Claims

1. A container having a tubular body terminating at one end in a moulding of plastics material characterised in that an annular portion of the tubular body extends laterally of the rest of tubular body and into the plastics moulding.

2. A container according to claim 1 characterised in that the annular portion extends inwardly and axially of the tubular body to define a shoulder portion of internal diameter less than the diameter of the rest of the tubular body.

3. A container according to claim 2 characterised in that the shoulder portion supports an outwardly flaring flange of maximum diameter less than the diameter of the tubular body.

4. A container according to claim 2 or claim 3 characterised in that the shoulder portion is a frustrum of a cone.

5. A container according to claim 4 characterised in that the included angle of the frustrum of the cone is in the range 60 to 900.

6. A container according to any preceding claim characterised in that the moulding is an annulus defining a mouth of the container.

7. A container according to any preceding claim characterised in that the tubular body is a composite of fibrous material and a plastics inner lining to which the moulding is fused.

8. A container according to any of claims 1 to 5 characterised in that the tubular body is made from sheet metal blank held in tubular shape by a side seam.

9. A method of forming a container having a tubular body terminating at one end in a moulding of plastics material characterised by the steps of providing a tubular body having at one end an annular portion extending laterally of the rest of the tubular body; clamping the annular portion between a mandrel inside the tubular body and a die member outside the body so that the terminal margin of the annular portion is in a mould cavity defined by said mandrel and die; and injecting a plastics material into the die cavity to form a moulding of plastics material on the terminal margin of the annular portion.

10. A method according to claim 9 characterised in that the annular portion is bent toward the axis of the tubular body to define a shoulder portion having a terminal edge of girth less than the girth of the tubular body.

11. A method according to claim 9 or 10 characterised in that the annular portion comprises a shoulder portion which supports an outwardly flaring flange of maximum girth less than the girth of the tubular body.

12. A method according to claims 10 or 11 characterised in that the shoulder portion is a frustrum of a hollow cone.

13. A method according to claim 11 characterised in that the included angle of the hollow cone is in the range between 600 and 900.

14. A method according to any one of claims 9 to 13 characterised in that the annular portion is formed as mandrel and die member close to clamp the annular portion.

15. A method according to any one of claims 9 to 14 characterised in that the tubular body is a composite of fibrous material and a plastics inner lining to which the moulding is fused during injection moulding.

16. A method according to any one of claims 9 to 14 characterised in that the tubular body is made from a sheet metal blank held in tubular shape by a side seam.

17. Apparatus for forming a container having a tubular body terminating at one end in a moulding of plastics material characterised by a mandrel enterable into the tubular body, a die member outside the tubular body adapted to co-operate with the mandrel to clamp an annular portion of the tubular body extending laterally of the tubular body; said mandrel, die members and die defining a mould cavity surrounding the free edge of the annular portion, and means through which a plastics material may be injected into the mould cavity to form a moulding of plastics material on the annular portion.

18. Apparatus according to claim 17 characterised in that a flared entry to the die member co-operates with a matching tapered surface on the mandrel to clamp a like flared annular portion of the tubular wall.

19. Apparatus according to claim 18 characterised in that the flared entry to the die member, tapered surface of the mandrel and annular portion of tubular wall are each frustoconical.

20. Apparatus according to claim 19 characterised in that the included angle of the frustoconical die member, tapered surface and annular portion are each within the range between 600 and 900.

21. Apparatus according to any one of claims 17 to 20 characterised in that stop blocks limit the clamping pressure on the annular portion.

22. A container substantially as hereinbefore described with reference to any one of the accompanying drawings.

23. A method of forming a container substantially as hereinbefore described with reference to Figs. 3,4 and 12 of the accompanying drawings.

24. Apparatus substantially as hereinbefore described with reference to Figs. 3,4 and 12 of the accompanying drawings.