GB2573574A

GB2573574A - Improvements to rotationally moulded cases

Info

Publication number: GB2573574A
Application number: GB1807696.8A
Authority: GB
Inventors: Bray David; Broom Garry
Original assignee: Leafield Environmental Ltd
Current assignee: Leafield Environmental Ltd
Priority date: 2018-05-11
Filing date: 2018-05-11
Publication date: 2019-11-13
Anticipated expiration: 2038-05-11
Also published as: GB201807696D0; GB2573574B; WO2019215452A1

Abstract

A multi-part mould 140 for use in a rotational moulding process to produce a plastics product, the mould comprising a first plurality of mould sections connected together and arranged in a first direction and a second plurality of mould sections connected together and arranged in a second direction, wherein the second direction is orthogonal to the second direction. The mould may include a central portion comprising a base section 142. A lower side wall section 156 may extend upwardly from base section and an upper side wall section 158 may extend upwardly from the lower side wall section. The mould may further include end base sections 144 and 146 that are attached to the ends of base section 142. End section lower side walls 160, 162, 170, 172 may extend upwardly from end base sections 144 and 146, and upper side wall section 164, 166, 174, 176 may extend upwardly from the end section lower side walls 160, 162, 170, 172 as shown. The mould may include a central lid section 180, an end lid section 168 that sits atop the upper side wall sections 164, 166 and the end wall section 150, and an end lid section 178 that sits atop the upper side wall sections 174, 176 and the end wall 30 section 154. When all of the abovementioned mould sections are assembled together they may form an enclosed internal volume into which a plastics powder may be introduced and heated as part of a rotational moulding process. It is an aim of the invention to provide a multi-part mould, in particular a ruggedized container, using rotational-moulding manufacture. Modular moulds provide the opportunity for products of various size to be produced without having to build a complete new mould.

Description

Improvements to Rotationally Moulded Cases

This invention relates to improvements to methods of production of cases and lids for cases.

The rotational moulding of plastics materials is a well-known technique for producing hollow plastics material parts. In such a process, a mould is charged with plastics powder and subsequently turned or rotated as the temperature of the mould is increased. As the plastics powder flows over the heated mould surface it becomes tacky and adheres to that surface so that that when all the powder is exhausted, a uniform layer of plastics material is formed. The mould is subsequently cooled, so the plastics material solidifies and the plastics part is then removed from the mould.

Being hollow products, ruggedized containers and cases have been commonly manufactured using the rotational moulding process. More recently however, some such containers, particularly the smaller flatter ones with high volume sales potential, have been injection moulded.

The advent of injection moulded cases has, to a large extent, detracted manufacturers investment and interest from rotationally-moulded products, resulting in reduced interest and development in rotationally-moulded cases in recent years. As a result, the design of rotationally-moulded cases has not kept pace with recent advances in the design and manufacturing techniques of rotationally-moulded articles.

The development of rotationally-moulded case design has therefore remained fairly static in recent years with minimal innovation.

A fixed design case is ideal for basic/standard applications, but the market for quality ruggedized cases frequently applies to more bespoke applications where the specific needs of the customer, or product to be contained, need to be taken into account.

Historically, rotationally-moulded cases bodies were designed around two-part operating moulds (bottom and top section) with each tool part being aligned to manufacture one product. However, there have been recent developments with respect to the creation of multi-part moulds for rotationally moulded cases. See, for example, the multi-part moulds shown in Figs. 1 -15 of GB2527745.

It is an aim of the present invention to provide a multi-part mould, in particular a ruggedized container, using rotational-moulding manufacture.

This aim is achieved by recognising the benefits of multi-part I modular moulds, and utilising these to significantly improve rotationally-moulded containers. The container thus produced may possess various novel features, which are described separately below.

The approach detailed below utilizes both multi-part moulds and modular moulds to increase design flexibility, reduce response time for bespoke designs and reduce investment costs in the long term.

Multi-part tooling allows additional features to be moulded in, whereas modular moulds provide the opportunity for products of various size to be produced without having to build a complete new mould, thus reducing investment and lead time. It can also mean bespoke designs can be more easily justified if investment in only one or two new sections of a mould are required.

In accordance with a first aspect of the present invention there is provided a multi-part mould for use in a rotational moulding process to produce a plastics product, the mould comprising a first plurality of mould sections connected together and arranged in a first direction and a second plurality of mould sections connected together and arranged in a second direction, wherein the second direction is orthogonal to the second direction.

The first direction may be vertical and the second direction may be horizontal.

The mould sections may be modular.

The mould may comprise a base mould section and a plurality of wall mould sections which extend substantially orthogonally from the base mould section when the mould is in the closed configuration.

The mould may comprise lower wall and upper wall mould sections. The lower wall mould sections could be removable.

In accordance with a second aspect of the present invention there is provided a method for producing a plastics product by rotational moulding comprising the steps of:

providing a multi-part mould in accordance with the first aspect, and using the mould for a rotational moulding process.

In accordance with a third aspect of the present invention there is provided a plastics case or lid produced by the method of the second aspect.

In accordance with a fourth aspect of the present invention there is provided a mould section, wherein the mould section is a wall section adapted to be used both as part of a multi-part mould for a case body and as part of a multi-part mould for a case lid.

Either multi-part mould may comprise a base section having a knife line. For the case body mould this may be a knife line located around an upper perimeter return, and for the lid mould this may be a knife line around a lower perimeter return. The case lid may comprise at least one deep rib to provide rigidity.

In accordance with a fifth aspect of the present invention there is provided a moulded case comprising integrated latch recesses and tie down points.

In accordance with a sixth aspect of the present invention there is provided a moulded case comprising mould-in relief graphics adjacent at least one of the list comprising: a handle, a tie down point, and a hoisting point.

In accordance with a seventh aspect of the present invention there is provided a multipart mould comprising a plurality of mould sections, the mould being moveable between open and closed configurations, the mould comprising first and second adjacent mould sections having respective co-operating projections spaced from the edges of the respective mould sections, arranged such that the co-operating projections abut when the mould is in the closed configuration, such that a plastics product produced using the mould comprises an open-ended channel extending within the body of the product, wherein the first mould section is rotatable about a pivot point wherein said pivot point is above the line along which the first and second adjacent mould sections meet in the closed configuration.

The invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 schematically shows a sectional view of a multi-part mould in accordance with an embodiment of the present invention;

Fig. 2 schematically shows a sectional view of the mould of Fig. 1;

Fig. 3 schematically shows a sectional view of a multi-part mould in accordance with an embodiment of the present invention;

Fig. 4 schematically shows a sectional view of the mould of Fig. 3;

Fig. 5 shows a view of a handle formed by the mould of Fig. 1;

Fig. 6 schematically shows a sectional view of a lid mould in accordance with an embodiment of the present invention;

Fig. 7 schematically shows a sectional view of a lid mould in accordance with an embodiment of the present invention;

Fig. 8 schematically shows a sectional view of a lid mould in accordance with an embodiment of the present invention;

Fig. 9 schematically shows a sectional view of a lid mould in accordance with an embodiment of the present invention;

Fig. 10 shows a perspective view of a moulded lid with deep ribs;

Fig. 11 shows a perspective view of a case body manufactured in accordance with the invention;

Fig. 12 shows a close-up view of the case body shown in Fig. 11;

Fig. 13 shows a partial side view of a case body manufactured in accordance with the invention, and close-up views of three parts of the case body;

Fig. 14 shows side views of three case bodies manufactured in accordance with the invention;

Fig. 15 shows side views of three lids manufactured in accordance with the invention;

Fig. 16 shows an exploded perspective view of a multi-part mould for a case body in accordance with an embodiment of the invention;

Fig. 17 shows an exploded perspective view of a multi-part mould for a case body in accordance with an embodiment of the invention;

Fig. 18 shows an exploded perspective view of a multi-part mould for a case body in accordance with an embodiment of the invention; and

Fig. 19 shows three exploded perspective views of multi-part moulds for lids in accordance with an embodiment of the present invention.

In all these figures and the below-described features, the container takes the form of a ruggedized case, for example for military applications. Other forms of container are of course possible within the scope of the present invention.

Fig. 1 schematically shows a sectional view of a multi-part mould 10 in accordance with an embodiment of the present invention. The mould 10 comprises a base section 16, a lower wall section 14 extending upwardly from the base section 16 and an upper wall section 12 extending upwardly from the lower wall section 14. The mould 10 is completed by a lid section 24 that sits atop the upper wall section 12 to form an enclosed internal volume into which a plastics powder may be introduced and heated as part of a rotational moulding process, as is well known in the art. It may be noted that only part of the complete mould 10 is shown in Fig. 1.

The upper wall section 12 comprises a first partial channel section 18. The lower wall section comprises a corresponding second partial channel section 20. When the mould 10 is assembled, the first partial channel section 18 and the second partial channel section 20 cooperate as shown to form an open ended channel that is contiguous with the enclosed internal volume of the mould 10. As a result, when a plastics product is rotationally moulded using the mould 10, the plastics product will comprise an integral channel. Said channel may be used as a carrying handle, hoisting point or tie-down point. As explained in GB2527745, such integral handles provide technical benefits over prior art handles that would need to be bolted on to a moulded product.

As an improvement to the mould shown in GB2527745, wherein the wall of moulded product in the region behind the handle would be deflected into the interior of the moulded product along the entire height of the product (see, for example, Fig. 7a of GB2527745 where the wall is deflected inwardly from the handle downwards), it can be seen from Fig. 1 of the present application that in the present invention the wall of the moulded product is only deflected into the interior of the moulded product in the area immediately adjacent the channel. This is because the upper wall section 12 comprises a curved wall section that extends into the interior volume of the mould 10 in the area above the first partial channel section 18 and extends away from the interior volume of the mould 10 in the area below the first partial channel section 18. As a result, the vertical wall of the lower wall section 14 extends vertically down from the upper wall section 12 at a point further outward from the interior volume of the mould 10 than in prior art moulds. This increases the total interior volume of the mould 10, and the interior volume of plastics products moulded using the mould 10.

As a further improvement to the mould shown in GB2527745, the pivot point P has been shifted upwards in the present invention. In both GB2527745 and the present invention the upper wall section 12 can be rotated in and out of the ‘closed’ position, i.e. the position in which the mould is complete and rotational moulding can take place. The direction of rotation from closed to open is indicated by an arrow in Fig. 5 of GB2527745, and it can be seen that the pivot point is below the modular split line, i.e. the point at which the upper wall section meets the lower wall section.

In the present invention, the pivot point P is above the modular split line. This allows the modular split line to extend diagonally downward as shown in Fig. 1. This in turn allows the upper wall section to comprise a curved surface that extends away from the interior volume of the mould in the region below the channel. Said diagonally downward extending modular split line has an additional benefit in that it allows the second partial channel section 20 to comprise a much shallower curve than in prior art mould sections, as the curve is almost tangential to the modular split line. This is also beneficial as the shallower split line angle is easier to access with a trimming tool I knife and is therefore easier to trim once moulding is complete.

It can be seen that in prior art mould sections (e.g. Fig. 5 of GB2527745) the second partial channel section is substantially U-shaped, comprising two essentially 90 degree curves to form a total curve of 180 degrees. In the present invention it can be seen that the partial channel section comprises a single curve of much greater than 180 degrees. The shallower curve also allows shorter shut offs at each end of the channel (see below). These shorter shut offs produce a shallower indent into the moulding. A shallower indent in turn produces a stronger moulding. A deeper indent (such as that shown in GB2527745) produces more localised thinning of the plastic wall directly above the shut off point (an effect similar to that produced by a knife line only less pronounced). The shallower indent produces less localised thinning in the plastic part wall.

It can be seen that the base section 16 comprises a third partial channel section 22. The third partial channel section 22 is arranged to cooperate with the first partial channel section 18 in a similar way to the second partial channel section 20 when the lower wall section 14 has been removed from the mould 10. This arrangement can be seen in Fig. 3.

Fig. 2 schematically shows a sectional view of the mould 10 of Fig. 1. Like reference numerals have been retained as appropriate. In this view, the channel formed by the cooperation of the first partial channel section 18 and the second partial channel section 20 is more clearly visible. In this view shut offs can be seen at each end of the second partial channel section 20 and the third partial channel section 22. One shut off is indicated by reference numeral 15. These shut offs are adapted to cooperate with adjacent mould wall sections where there is no channel to be formed, e.g. above third partial channel section 22 in Fig. 2. The shut offs bear against an adjacent mould wall section to prevent molten plastic powder from entering the partial channel section during rotational moulding, as is described in detail in GB2527745. However, in the present invention, said shut offs are less pronounced than those in the prior art. This is due to the partial channel sections having a shallower curve, as described above, due the diagonally downwardly extending modular split line.

Fig. 3 schematically shows a sectional view of a multi-part mould 26 in accordance with an embodiment of the present invention. The mould 26 comprises a base section 30 and a wall section 28 extending upwardly from the base section 16. The mould 26 is completed by a lid section 36 that sits atop the wall section 28 to form an enclosed internal volume into which a plastics powder may be introduced and heated as part of a rotational moulding process, as is well known in the art. It may be noted that only part of the complete mould 26 is shown in Fig. 3.

The wall section 28 comprises a first partial channel section 32. The base section 30 comprises a corresponding second partial channel section 34. When the mould 10 is assembled, the first partial channel section 32 and the second partial channel section 34 cooperate as shown to form an open ended channel that is contiguous with the enclosed internal volume of the mould 26. As a result, when a plastics product is rotationally moulded using the mould 10, the plastics product will comprise an integral channel. Said channel may be used as a carrying handle, hoisting point or tie-down point. As explained in GB2527745, such integral channels provide technical benefits over prior art channels that would need to be bolted on to a moulded product.

As an improvement to the mould shown in GB2527745, wherein the wall of moulded product in the region behind the channel would be deflected into the interior of the moulded product along the entire height of the product (see, for example, Fig. 7a of GB2527745), it can be seen from Fig. 3 of the present application that in the present invention the wall of the moulded product is only deflected into the interior of the moulded product in the area immediately adjacent the channel. This is because the wall section 28 comprises a curved wall section that extends into the interior volume of the mould 26 in the area above the first partial channel section 32 and extends away from the interior volume of the mould 26 in the area below the first partial channel section 32. As a result, wall section 28 meets the base section 30 at a point further outward from the interior volume of the mould 26 than in prior art moulds. This increases the total interior volume of the mould 26, and the interior volume of plastics products moulded using the mould 26.

Naturally the beneficial increase in volume is less pronounced for moulded cases in which no lower wall section is present in the mould (e.g. moulds such as that shown in Fig. 3) compared to cases in which a lower wall section is present in the mould (e.g. moulds such as that shown in Fig. 1). However, even in cases where no lower wall is present in the mould a deeper base section can be used to provide a similar increase in volume to moulds having a lower wall.

Fig. 4 schematically shows a sectional view of the mould 26 of Fig. 3. Like reference numerals have been retained as appropriate. In this view, the channel formed by the cooperation of the first partial channel section 32 and the second partial channel section 34 is more clearly visible. One of the shut offs is indicated by reference numeral 35.

Fig. 5 shows a view of a handle 38 formed by the mould 10 of Fig. 1. As can be seen, only the area 40 immediately adjacent the handle 38 is deflected inwardly into the body of the moulded plastics product. The wall 42 of the moulded plastics product beneath the handle 38 is further outward than the area 40.

Fig. 6 schematically shows a sectional view of a lid mould 44 in accordance with an embodiment of the present invention. The mould 44 comprises a base section 46 and a wall section 48 extending upwardly from the base section 46. The mould 44 is completed by a lid section 50 that sits atop the wall section 48 to form an enclosed internal volume into which a plastics powder may be introduced and heated as part of a rotational moulding process, as is well known in the art. It may be noted that only part of the complete mould 44 is shown in Fig. 6.

Fig. 7 schematically shows a sectional view of a lid mould 52 in accordance with an embodiment of the present invention. The mould 52 comprises a base section 54, a lower wall section 56 extending upwardly from the base section 46, and an upper wall section 58 extending upwardly from the lower wall section 56. The mould 52 is completed by a lid section 60 that sits atop the upper wall section 58 to form an enclosed internal volume into which a plastics powder may be introduced and heated as part of a rotational moulding process, as is well known in the art. It may be noted that only part of the complete mould 52 is shown in Fig. 7.

In Fig. 7 the upper wall section 58 is an upper wall section used in moulding of a case body, i.e. the same component as item 11 shown in Fig. 5 of GB2527745. The reuse of case body moulds in the moulding of lids allows flexibility in manufacturing, and the production of an entirely new set of lids using a small basic set of mould sections. The upper wall section 58 can be seen to comprise a partial channel section 55, but this is closed off by shut offs at each end of the partial channel section 55 so that molten plastic powder does not enter the partial channel section 55 in the arrangement shown in Fig. 7.

Lid 44 (without the side wall spacer) would normally be a double skin lid with interior space used for structural ribs and kiss off points. In the lid mould 52 shown in Fig. 7, substantial internal space is achieved in lids produced using the mould 52 as there is a significant height different between the lid lower surface and the lid upper surface. However, in lids produced using such moulds the space formed by the height differential between the lid upper and lower surfaces is inaccessible unless at least a portion of the lid lower surface is cut away.

Fig 8 shows the knife line point in place but it is not used when there is no lid side wall spacer present. Fig. 9 discloses a lid mould 72 in which the additional lid internal space may be readily utilised, and so provide additional internal volume to a case when the lid sits atop a case.

Fig. 8 schematically shows a sectional view of a lid mould 62 in accordance with an embodiment of the present invention. Similarly to Fig. 6, the mould 62 comprises a base section 64 and a wall section 68 extending upwardly from the base section 64. The mould 62 is completed by a lid section 70 that sits atop the wall section 68 to form an enclosed internal volume into which a plastics powder may be introduced and heated as part of a rotational moulding process, as is well known in the art. It may be noted that only part of the complete mould 62 is shown in Fig. 8.

The lid section 64 comprises a knife point 66. The knife point 66 is point at which the lid section 64 comes to a sharp edge. When the mould 62 is used in a rotational moulding process, melted plastic adhering to the lid section 64 in the region of the knife point 66 will be thin due to the extremely small surface area along the sharp edge. As a result the wall of the lid moulded using the mould 62 will be thin, and therefore weak, in this region. Consequently, a lower surface of a lid moulded using the mould 62 can be removed from the rest of the lid by separating the lid lower surface along the knife point region. When the lid lower surface has been removed in this way, access will be provided into the previously enclosed interior volume of the lid, with the upper surface of the lid essentially acting as both the upper and lower surface of the lid. However, as mentioned above this would not generally be done in the relatively shallow lid arrangement shown in Fig. 8.

In applications where there is little space between the moulding walls it is possible to replace the knife line with a sharp 90° comer. This corner has the effect of reducing the thickness of the moulded plastics wall over the corner, which makes it easier to trim out compared to a moulded plastics wall of normal thickness. The local thinning is less than that produced by a knife line but trimming with a knife is still facilitated, particularly when the moulded product is still warm from the moulding process.

In some applications the knife line or sharp 90° corner can be omitted entirely, and the lid lower surface can simply be cut out using standard manufacturing techniques, e.g. by routing, or by using a jigsaw I multisaw.

Fig. 9 schematically shows a sectional view of a lid mould 72 in accordance with an embodiment of the present invention. Similarly to Fig. 7, the mould 72 comprises a base section 74, a lower wall section 78 extending upwardly from the base section 74, and an upper wall section 80 extending upwardly from the lower wall section 78. The mould 72 is completed by a lid section 82 that sits atop the upper wall section 80 to form an enclosed internal volume into which a plastics powder may be introduced and heated as part of a rotational moulding process, as is well known in the art. It may be noted that only part of the complete mould 72 is shown in Fig. 9.

The upper wall section 80 is the same component as item 14 shown in Fig. 1.

Therefore, the present invention envisages the re-use of case wall mould sections in the moulding of case lids. This allows for the production of deep lids without the need for a new set of mould sections manufactured for this purpose. The upper wall section 80 comprises a partial channel section 85, but as no channel is to be moulded in the lid a pair of shut offs at each end of the partial channel section 85 cooperate with the lid section 82 to prevent molten plastic powder from entering the partial channel section 85 during rotational moulding of the lid.

The lid section 74 comprises a knife point 76. As explained above with respect to Fig. 8, the knife point 76 is point at which the lid section 74 comes to a sharp edge. When the mould 72 is used in a rotational moulding process, melted plastic adhering to the lid section 74 in the region of the knife point 76 will be thin due to the extremely small surface area along the sharp edge. As a result the wall of the lid moulded using the mould 72 will be thin, and therefore weaker, in this region. Consequently, a lower surface of a lid moulded using the mould 72 can be removed from the rest of the lid by separating the lid lower surface along the knife point region. When the lid lower surface has been removed in this way, access will be provided into the previously enclosed interior volume of the lid, with the upper surface of the lid essentially acting as both the upper and lower surface of the lid.

In prior art moulded lids, the presence of both an upper and lower lid surface would give strength and rigidity to the lid. As the present invention proposes the removal of one of at least a portion of the lower lid surface, it has been found to be beneficial to strengthen the lid by providing one or more deep rib in the lid upper surface. Fig. 10 shows a perspective view of a moulded lid 84 with deep ribs 86.

Fig. 11 shows a perspective view of a case body 92 manufactured in accordance with the invention.

In certain applications it may be desirable to minimize the number of channels in a wall of a moulded case. For example, where the aim is to maximize the internal volume of the moulded case. To this end, multiple case features may be combined in to one channel recess. An example of this is shown at 94 in Fig. 12, where a latch recess is combined with a tie down point. In prior art cases, these features would be provided on two separate adjacent channels.

Fig. 12 shows a close-up view of the case 92 shown in Fig. 11. The latch recess is indicated at 96 and the tie down point is indicated at 98. If the latch recess 96 were to moulded either side of the tie down point 98, it would require its own recess. This would be detrimental as it would reduce the overall interior volume of the case. It would also necessitate a corresponding recess in the lid due to tool modularity, which may also be undesirable. By moulding the latch recess 96 and the tie down point 98 in the vertical configuration shown in Fig. 13, both case features are beneficially provided within a single recess.

Fig. 13 shows a partial side view of a case 100 manufactured in accordance with the invention, and close-up views of three parts of the case 100.

As discussed above with respect to Figs. 1-4, integral channels in moulded cases may be provided to serve a number different functions, e.g. carrying handle, hoisting point, tie down point, etc. The different functions may require the channel to have different physical properties, e.g. a hoisting point may require a channel with greater cross section to give stronger walls than a carrying handle. The misidentification of a particular channel could be disadvantageous, or even dangerous. For example, if a carrying handle is misidentified as a hoisting point then hoisting equipment could cause damage to the carrying handle, and an improperly hoisted case could present a hazard to workers handling the case or nearby equipment.

To reduce the chance of misidentification, the present invention provides moulds capable of producing mould in relief graphics moulded into the wall of a case in the region adjacent an integral channel. As can be seen in Fig. 13, the case 100 has moulded indicia for a hoisting point 102, a tie down point 104 and a carrying handle 106 on the case wall just above the respective channels. Close-up views of the indicia 102, 104, 106 are shown in the lower portion of Fig. 13. The relevant mould section is engraved to produce the identifying graphics in relief.

Fig. 14 shows side views of three case bodies 108a, 108b, 108c manufactured in accordance with the invention.

A first case body 108a comprises a central section 110 and long end sections 112, 114. The total length of the case is 2200mm.

A second case body 108b comprises a central section 110 and medium end sections 116, 118. The total length of the case is 1800mm.

A third case body 108c comprises a central section 110 and short end sections 120, 122. The total length of the case is 1400mm.

All of the three cases 108a-c are one-piece rotationally moulded products. The same reference numeral 110 has been used to indicate the central section in each case to indicate that the same mould sections have been used in each case to form this part in a rotational moulding process. The tooling lines between the central sections 110 and the respective end sections are shown in dotted line in each case so show where the central mould sections (middle section comprised of base, lower side wall, upper side wall and top) meets each end mould section. The tooling line is stepped to provide a “brick pattern”. This gives the moulded case strength where adjacent sections meet. It also creates space at the base of a short case for wheel recesses to be included and space for a bolting flange at the top.

Fig. 16 shows side views of three lids 124a, 124b, 124c manufactured in accordance with the invention.

A first lid 124a comprises a central section 126 and long end sections 128, 130. The total length of the lid is 2200mm.

A second case body 124b comprises a central section 126 and medium end sections 132, 134. The total length of the lid is 1800mm.

A third case body 124c comprises a central section 126 and short end sections 136, 138. The total length of the lid is 1400mm.

All of the three lids 124a-c are one-piece rotationally moulded products. The same reference numeral 126 has been used to indicate the central section in each lid to indicate that the same mould sections have been used in each lid to form this part in a rotational moulding process. The tooling lines between the central sections 126 and the respective end sections are shown in dotted line in each lid so show where the central mould section meets each end mould section.

The present invention (in conjunction with the removal of lower body side walls for reuse as part of the lid mould) provides multi-part moulds for rotationally moulded products exhibiting both vertical and horizontal modularity. This represents a clear improvement over moulds having only vertical modularity, as with vertical modularity only two different cases can be immediately manufactured from one set of moulds (i.e. a case body with the mould fully assembled, and a case body with mould fully assembled but with the lower set of walls removed). Additional walls of different heights are required to further add to the modularity and case height options.

The introduction of combined vertical and horizontal modularity changes the variables significantly, particularly if tooling is, or has been, purchased for one or more modular lengths of case. If, for instance, the tooling necessary to build three different lengths of case body and lids as shown in Figs. 14 and 15 is available, a total of twenty different case configurations can be built.

The three modular cases bodies and lids shown are of the following lengths: 2200mm, 1800mm and 1400mm and all are 500mm high.

Vertical modularity creates an additional case body height of 321mm (via the removal of the lower wall section moulds), and so there are two case body heights for each length,

i.e. a total of six case bodies

If horizontal modularity is added to the case bodies, and said modularity is asymmetrical, i.e. a long end section at one end of the case a short end section at the other end of the case, a further two case lengths (2000mm and 1600mm) can be produced, each of which has two heights, i.e. an accumulative total often case bodies

The three modular cases lids shown are of the following lengths - 2200mm, 1800mm and 1400mm and all are 150mm high.

Vertical modularity (via the inclusion of a lower body wall section mould in the lid mould) creates an additional case lid height of 429mm, and so there are two case lid heights for each length, i.e. a total of six lids

If horizontal modularity is added to the lids, and said modularity is asymmetrical, i.e. a long end section at one end of the lid a short end section at the other end of the lid, a further two lid lengths (2000mm and 1600mm) can be produced, each of which has two heights, i.e. an accumulative total often lids.

Each case body has two case lid height options creating a total of twenty cases, all from three complete case tool build configurations. It should also be noted here that it is not necessary to purchase a full set of tooling sections to build each case, only a small number of additional parts are required for each successive new build. For instance, once the initial tooling has been placed for the 2200mm long case body (consisting of twenty two modular panels), only an additional twelve panels are required to make a case body of 1800mm in length. To make a 1400mm long case only an additional four modular tool mould panels are required. The advantage of combined height and length modularity is clearly evident.

Fig. 16 shows an exploded perspective view of a multi-part mould 140 for a case body in accordance with an embodiment of the invention. The mould 140 corresponds to the moulded case 108a shown in Fig. 14.

The mould 140 comprises a central portion comprising a base section 142. A lower side wall section 156 extends upwardly from base section 142 and an upper side wall section 158 extends upwardly from the lower side wall section 156. Corresponding lower and upper side wall sections are present at the rear of the mould, but cannot be seen in this view.

The mould 140 further comprises end base sections 144 and 146 that are attached to the ends of base section 142. End section lower side walls 160, 162, 170, 172 extend upwardly from end base sections 144 and 146, and upper side wall section 164, 166, 174, 176 extend upwardly from the end section lower side walls 160, 162, 170, 172 as shown.

The mould further comprises lower end walls 148 and 152 that extend upwardly from the end base sections 144 and 146 as shown. Upper end walls 150, 154 extend upwardly from the lower end walls 148 and 152 as shown.

Finally, the mould 140 is completed by a central lid section 180, an end lid section 168 that sits atop the upper side wall sections 164, 166 and the end wall section 150, and an end lid section 178 that sits atop the upper side wall sections 174, 176 and the end wall section 154.

When all of the abovementioned mould sections are assembled together they form an enclosed internal volume into which a plastics powder may be introduced and heated as part of a rotational moulding process, as is well known in the art.

Fig. 17 shows an exploded perspective view of a multi-part mould 240 for a case body in accordance with an embodiment of the invention. The mould 240 corresponds to the moulded case 108b shown in Fig. 14.

The mould 240 comprises a central portion comprising a base section 242. A lower side wall section 256 extends upwardly from base section 242 and an upper side wall section 258 extends upwardly from the lower side wall section 256. Corresponding lower and upper side wall sections are present at the rear of the mould, but cannot be seen in this view.

The mould 240 further comprises short end base sections 244 and 246 that are attached to the ends of base section 242. Short end section lower side walls 260, 262, 270, 272 extend upwardly from short end base sections 244 and 246, and short upper side wall section 264, 266, 274, 276 extend upwardly from the short end section lower side walls 260, 262, 270, 272 as shown.

The mould further comprises lower end walls 248 and 252 that extend upwardly from the end base sections 244 and 246 as shown. Upper end walls 250, 254 extend upwardly from the lower end walls 248 and 252 as shown.

Finally, the mould 240 is completed by a central lid section 280, a short end lid section 268 that sits atop the upper side wall sections 264, 266 and the end wall section 250, and a short end lid section 278 that sits atop the upper side wall sections 274, 276 and the end wall section 254.

Fig. 18 shows an exploded perspective view of a multi-part mould 340 for a case body in accordance with an embodiment of the invention. The mould 340 corresponds to the moulded case 108c shown in Fig. 14.

The mould 340 comprises a central portion comprising a base section 342. A lower side wall section 356 extends upwardly from base section 342 and an upper side wall section 358 extends upwardly from the lower side wall section 356. Corresponding lower and upper side wall sections are present at the rear of the mould, but cannot be seen in this view.

The mould 340 further comprises end base sections 344 and 346 that are attached to the ends of base section 342. However, in this mould there are no end section upper or lower side walls, as this mould produces a short case body.

The mould further comprises lower end walls 348 and 352 that extend upwardly from the end base sections 344 and 346 as shown. Upper end walls 350, 354 extend upwardly from the lower end walls 348 and 352 as shown.

Finally, the mould 340 is completed by a central lid section 380, an end lid section 368 that sits atop the upper end wall 350, and an end lid section 378 that sits atop the upper the end wall section 354.

Fig. 19 shows three exploded perspective views of multi-part moulds 400a, 400b, 400c for lids in accordance with an embodiment ofthe present invention.

The mould 400a comprises a central mould section 402, comprising a base, sidewalls and a top. A pair of long end base sections 404, 406 are attached to each end of the assembled central mould section 402. A pair of corresponding long end lid sections 408, 410 are also attached to each end of the central mould section 402. A pair of long end sidewall sections 412, 414 are disposed between the long end base section 404 and long end lid section 408 at one end of the central mould section 402. A pair of long end sidewall sections 416, 418 are disposed between the long end base section 406 and long end lid section 410 at the other end of the central mould section 402. Finally, the mould 400a is completed by a mould end section 420, 422 at each end.

The mould 400b comprises a central mould section 402, comprising a base, sidewalls and a top. A pair of medium end base sections 424, 426 are attached to each end of the assembled central mould section 402. A pair of corresponding medium end lid sections 428, 430 are also attached to each end of the central mould section 402. A pair of medium end sidewall sections 432, 434 are disposed between the medium end base section 424 and medium end lid section 428 at one end of the central mould section 402. A pair of medium end sidewall sections 436, 438 are disposed between the medium end base section 426 and medium end lid section 430 at the other end of the central mould section 402. Finally, the mould 400b is completed by a mould end section 440, 442 at each end.

The mould 400c comprises a central mould section 402, comprising a base, sidewalls and a top. A pair of short end base sections 444, 446 are attached to each end of the assembled central mould section 402. A pair of corresponding short end lid sections 448, 450 are also attached to each end of the central mould section 402. Finally, the mould 400c is completed by a mould end section 452, 454 at each end. The sidewall sections are omitted entirely in this embodiment.

The mould 400a corresponds to the lid 124a shown in Fig. 15. The mould 400b corresponds to the lid 124b shown in Fig. 15. The mould 400c corresponds to the lid 5 124c shown in Fig. 15.

The above-described embodiments are exemplary only, and other possibilities and alternatives within the scope of the invention will be apparent to those skilled in the art.

Claims

1. A multi-part mould for use in a rotational moulding process to produce a plastics product, the mould comprising a first plurality of mould sections connected together and arranged in a first direction and a second plurality of mould sections connected together and arranged in a second direction, wherein the second direction is orthogonal to the second direction.

2. A mould according to claim 1, wherein the first direction is vertical and the second direction is horizontal.

3. A mould according to claim 1 or 2, wherein the mould sections are modular.

4. A mould according to any preceding claim, comprising a base mould section and a plurality of wall mould sections which extend substantially orthogonally from the base mould section when the mould is in the closed configuration.

5. A mould according to claim 4, comprising lower wall and upper wall mould sections.

6. A mould according to claim 5, wherein the lower wall mould sections are removable.

7. A method for producing a plastics product by rotational moulding, the method comprising the steps of:

providing a multi-part mould in accordance with any of claims 1 to 6, and using the mould for a rotational moulding process.

8.

A plastics case body produced by the method of claim 7.

9. A plastics lid produced by the method of claim 7.