GB2171048A

GB2171048A - Containers

Info

Publication number: GB2171048A
Application number: GB08602710A
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: 1986-02-04
Publication date: 1986-08-20
Also published as: GB8503728D0; GB8602710D0; GB2171046A; GB2171048B

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

1 GB2171048A 1

SPECIFICATION

Containers This invention relates to a container having a 70 tubular side wall terminating at at least one end in a moulding of plastics material, and also to a method of making such a container and to apparatus for carrying out the method.

British Patent 1,275,051 describes contain- 75 ers 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 man- 80 drel 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 85 of the tubular body. A front member of the mould seals against the cylindrical exterior of the tubular body. Injection of a plastics ma terial, 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 per mit jumping out may bring the problem that injection moulding pressures may force the tu- 100 bular body out of the front member mould before the moulding is completely formed.

Containers of the kind mentioned have also previously been proposed in British Patents 1 010 541 and 1 518 307. However, whereas 105 in the case of the containers proposed in those Patents (viz collapsible toothpaste tubes) caps are involved which have to be removable, the present invention is concerned with a container having a moulded rim which must 110 remain fixed in order to serve the objects of the present invention which are:

1. To reinforce an end of a wide mouthed tube of fibrous material OR to make safe the raw edge of a wide mouthed welded metal tube.

2. To seal the end fibres of a composite wall to prevent fluff coming off.

3. To get a continuum of plastics material from the plastic lining of a fibrous tube to the 120 plastics material of the rim.

4. To provide a component that can either be a complete end closure or alternatively be a ring that will receive a removable lid.

5. To provide a moulding that can either close round or rectilinear crosssection tubes or serve as a rim to receive a lid: eg. a round rim for a round lid or a square rim to receive a round plug lid.

With the problems and object hereinbefore 130 discussed in mind, the present invention, in a first aspect thereof, comprises a method of forming a container having a tubular side wall terminating at at least one end in a moulding of a plastics material, said method comprising the steps of: (a) forming a said tubular side wall from sheet material; (b) deforming a margin at at least one end of said tubular side wall to create a radially inwardly directed shoulder portion and a flange extending radially outwardly from the radially inner periphery of the shoulder portion; (c) clamping said margin between a mandrel inside the tubular side wall and an end face of a die having a cavity to define a said moulding; and (d) injecting plastics material into the die cavity to form said moulding at least on the surfaces of the flange and adjacent part of the shoulder which are external of the container.

Preferably the tubular side wall is formed by winding of paper board or like fibrous material. Alternatively, the tubular side wall may be formed by bending of a rectangular blank of sheet metal such as tin plate, adjacent edges of the blank being joined by welding, soldering or folding.

The shoulder portion may be formed to the shape of a hollow frustum of a cone, the included angle of said cone being in the range 60 to 90 degrees. The outwardly extending flange may be formed substantially in the shape of a hollow frustum of a cone of external diameter less than the external diameter of the shoulder portion, so permitting the die face to reach the shoulder portion for clamping against the mandrel.

The die cavity may surround both the exterior and interior surfaces of the flange to define, after moulding, an annular rim in which the flange is embedded. Preferably during moulding a central surface of the die cavity is located, in spaced relationship with an end face of the mandrel to define a central panel of the moulding within the rim.

According to the invention, in a second aspect thereof, apparatus for carrying out the method in accordance with the said first aspect of the invention includes stop block means for limiting the pressure of said clamp- ing.

According to the invention, in a third aspect thereof, a container made by a method or in apparatus according to the said first and second aspects of the invention respectively has a tubular side wall of round cross-section, and preferably its minimum cross-sectional area within the shoulder portion is at least 75% of the cross-sectional area of the rest of the tubular side wall.

The tubular side wall may be made of plastics mater ial or alternatively a composite of a fibrous material and an interior lining of a plastics material to which the moulding is fused during injection moulding.

The tubular side wall may be of a fibrous 2 GB2171048A 2 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 of use on metal tubular bodies.

Alternatively the tubular side wall is made from a flat blank held in tubular form by a side seam. For example a rectangular blank held in tubular form by a lap weld in which case the plastics moulding seals against the unevenlap. 20 In one embodiment of the apparatus a flared 85 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. The flared entry to the die member, tapered 90 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 with the range between 60 degrees and 90 degrees.

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

Another advantage arising from use of rela tive motion as between the mandrel and die member in a direction parallel to the axis of 105 the container to clamp a peripheral margin of the annular portion is that reversal of the mo tion releases the finished moulding without re course to "jumping out" or split tooling.

Various embodiments will now be described 110 by way of example and with reference to the accompanying drawings in which Figure I 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 round a tubular body.

Figure 4 is an enlarged fragmentary view of modified tooling showing the position of 120 clamping; Figure 5 is a side view, sectioned on a dia meter, of a container having a moulded ring fused to an interior lining.

Figure 6 is a like view of 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 fragmentary view of a container with overcap; Figure 10 is a fragmentary view of a metal container with plastics rim; and Figure 11 is a diagrammatic 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 side wall or 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 portion 6 which supports an outwardly directed flange 7. The shoulder portion 6 is in the form of a frustum of a hollow cone of included angle substantially 90 degrees. It is desirable to have a fairly steep slope on the shoulder portion 6 so that the conical shape is able to support the top load arising during lidding and subsequent stacking of filled containers. The shoulder portion 6 depicted in the tooling of Fig. 4 has an included angle of 60 degree.

Fig. 3 shows diagrammatically 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 portion 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 12 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 3 GB2171048A 3 moulding.

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

The top tool 12 is lowered so that the ta- pered 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 mem- ber 11 and the tapered surface 25 of the mandrel are inclined at 60 degrees to the central axis of the tubular body or cylindrical surface of the mandrel 10. This corresponds to an included cone angle of 60 degrees. In Fig.

3 the inclination of tapers 25, 26 to the cylindrical surface of the mandrel 10 is 45 degrees corresponding to an included cone angle of the shoulder portion 6.

While the shoulder portion 6 is clamped be- tween 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 portion 6 and flange 7. Suitable plastics materials include polyethylene, polypropylene and 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 springs 19 to force the moulded collar 3 and tubular body 2 out of the die 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 12 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 11 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 a 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 col- lars 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 ex tends into the interior of the container to de fine a receiving surface 36 for a plug lid. An advantage of this arrangement is that the ma- terial 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 mould- ing. 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 a flange 48 extending radially outwardly from an annular portion in the form of a frustoconical shoulder portion 41. The shoulder portion 41 is embedded in a rim 42 of plas- tics 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.

An advantage of the container of Fig. 9 is that the shoulder 6 and flange 7 support the collar 34 inboard of the rest of the tubular body 32 so that the curled skirt 55 of overcap 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 4 GB2171048A 4 reinforcing the rim of tubular bodies of fibrous materials it is not limited thereto.

Fig. 10 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. 10 the tubular body 60 has a shoulder 6 and flange 7 embedded in the rim of plastics material cornprising 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. 11 shows apparatus for operating the tools of Fig. 3 or Fig. 4. The apparatus cornprises 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 plas- tics 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 underside 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 tubu- 120 lar bodies of other cross-section such as rectilinear or polygonal peripheral shape.

Claims

1. A method of forming a container having a tubular side wall terminating at at least one end in a moulding of a plastics material, said method comprising the steps of: (a) forming a said tubular side wall from sheet material; (b) deforming a margin at at least one end of said tubular side wall to create a radially inward directed shoulder portion and a flange extending radially outwardly from the radially inner periphery of the shoulder portion; (c) clamping said margin between a mandrel inside the tubular side wall and an end face of a die having a cavity to define a said moulding; and (d) injecting plastics material into the die cavity to form said moulding at least on the surfaces of the flange and adjacent part of the shoulder which are external of the container.

2. A method according to Claim 1 wherein the tubular side wall is formed by winding of paper board or like fibrous material.

3. A method according to Claim 1 wherein the tubular side wall is formed by bending of a rectangular blank of sheet metal such as tin plate, adjacent edges of the blank being joined by welding, soldering or folding.

4. A method according to any one of the preceding claims wherein the shoulder portion is formed to the shape of a hollow frustum of a cone, the included angle of said cone being in the range 60 to 90 degrees.

5. A method according to any one of the preceding claims wherein the outwardly extending flange is formed substantially in the shape of a hollow frustum of a cone of external diameter less than the external diameter of the shoulder portion, so permitting the die face to reach the shoulder portion for clamping against the mandrel.

6. A method according to any one of the preceding claims wherein the cavity surrounds both the exterior and interior surfaces of the flange to define, after moulding, an annular rim in which the flange is embedded.

7. A method according to Claim 6 wherein, during moulding, a central surface of the die cavity is located, in spaced relationship with an end face of the mandrel to define a central panel of the moulding within the rim.

8. A method according to Claim 1 of forming a container, the method being substantially as hereinbefore described with reference to at least one of Figs. 1 to 7 and Figs. 9 to 11 of the accompanying diagrammatic drawings.

9. A method according to Claim 1 of forming a container, the method being substantially as hereinbefore described with reference to at least one of the accompanying diagrammatic drawings.

10. Apparatus for carrying out the method according to any one of the preceding claims and including stop block means for limiting the pressure of said clamping.

11. Apparatus according to Claim 10 and constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in Figs. 3, 4 and 11 of the accompanying diagrammatic drawings.

12. A container made by a method or in apparatus according to any one of the preced- ing claims wherein the tubular side wall has a GB2171048A 5 round cross-section.

13. A container according to Claim 12 wherein the minimum cross-sectional area within the shoulder portion is at least 75% of the cross-sectional area of the rest of the tubular side wall.

14. A container according to Claim 12 and constructed substantially as hereinbefore described with reference to and as illustrated in at least one of Figs. 1, 2, 3, 4, 5, 6, 7, 9 and 10 of the accompanying diagrammatic drawings.

15. A container according to Claim 12 and constructed substantially as hereinbefore described with reference to and as illustrated in at least one of Figs. 1 to 10 of the accompanying diagrammatic drawings.

Printed in the United Kingdom for Her Majesty's Stationery Office, Did 8818935, 1986, 4235. Published at The Patent Office, 25 Southampton Buildings. London. WC2A 'I AY, from which copies may be obtained-