WO2007034176A2

WO2007034176A2 - Unloading apparatus for rotationnaly moulded articles, and unloading method related thereto

Info

Publication number: WO2007034176A2
Application number: PCT/GB2006/003493
Authority: WO
Inventors: Henry Stevens; John Dawson
Original assignee: Pvaxx Research And Development Limited
Priority date: 2005-03-18
Filing date: 2006-09-20
Publication date: 2007-03-29
Also published as: WO2007034176A3

Abstract

Apparatus for unloading articles from a moulding apparatus tiaving a plurality of moulds is disclosed. The unloading apparatus (24) comprises a support (54) and a plurality of holder pairs rotatably connected to the support. Each holder pair is configured to hold at least one said article, wherein the holder pairs are movable to release the article (s) held thereon. Also disclosed is a system for moulding articles, comprising a rotational mould apparatus (23) having a plurality of moulds and means for driving the apparatus between a fill position and an unload position, wherein the spatial position of the apparatus when in the fill position is different to the spatial position of the apparatus when in the unload position. A manufacturing system and plant for manufacturing moulded articles comprises at least one unit (22). The unit comprises at least one article moulding system as described above and corresponding said article unloading apparatus as described above for unloading articles from a corresponding said article moulding system.

Description

SYSTEMS, APPARATUS AND METHODS FOR MOULDING AND SYSTEMS, APPARATUS AND METHODS RELATED THERETO

TECHNICAL FIELD

The present invention relates to systems, apparatus and methods for moulding and systems, apparatus and methods related thereto. In particular, the present invention relates to systems and apparatus for rotational moulding of polymeric articles.

BACKGROUND ART

Rotational moulding is one of several well known methods of moulding and may comprise the rotation of a mould, after part-filling with mould material, about two perpendicular axes typically to produce a polymeric or plastic hollow article. In a typical rotational moulding process, a mould tool is part- filled with mould material, and the mould rotated in an oven. The oven is then heated to melt the mould material in the mould while the mould is rotated. After a predetermined time, the mould is cooled to consolidate the melted mould material therein and for the polymer to form the desired, moulded shape. The mould is then removed from the oven and the article removed from the mould.

Rotational moulding is particularly useful for producing hollow articles. As pressure is applied in the insertion of the mould material in the mould, and also because the mould material is heated and cooled in the mould, the resulting moulded article has relatively lower stress.

Historically, rotational moulding tends to be limited in terms of size of scale, limiting the size of article which can be moulded and the number of articles able to be produced within a given timeframe. Furthermore, compared to 2006/003493

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other moulding methods, such as injection moulding, rotational moulding is relatively slow. However injection moulding has its own limitations. For example, injection moulding is not appropriate for moulding relative large objects, due to the pressures the mould must be able to withstand.

It is an object of at least one of the preferred embodiments of the present invention to overcome or ameliorate at least one of the deficiencies of the prior art, or at least to provide a suitable alternative thereto.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided apparatus for unloading articles from a moulding apparatus having a plurality of moulds, the unloading apparatus comprising: a support: and a plurality of holder pairs rotatably connected to the support, each holder pair configured to hold at least one said article; wherein the holder pairs are movable to release the article(s) held thereon.

This aspect of the invention is advantageous in that it allows improved retrieval of a plurality of moulded articles at once from a moulding apparatus having a plurality of moulds.

Preferably the holder pairs are arranged to release the article(s) in a stacked configuration. Preferably the holder pairs are arranged vertically with respect to each other. The holders in each said holder pair may be horizontally opposed to each other and may be arranged to rotate inwardly with respect to each other. Preferably the holders of each said holder pair have parallel axes of rotation. - 3 -

Preferably the unloading apparatus is arranged such that the holder pairs are rotatable in a sequential arrangement from an uppermost holder pair to a lowermost holder pair, to provide a stack of unloaded articles. Preferably, the apparatus comprises sequencing means causing the holder pairs to rotate in said sequential arrangement.

The moulding apparatus is preferably a rotational moulding apparatus.

Preferably the respective cavities of the moulds are generally planar.

Preferably the holders are arm-like and each extend longitudinally in a common direction from a portion of the support. There are preferably eight said holder pairs, each of which is preferably configured to hold two articles side-by-side.

Preferably the support is movable to move the holder arms between an article retrieval position and an article withdrawal position with respect to the moulding apparatus.

Preferably the articles are load bearing articles, and more preferably the articles are pallets.

Preferably each article is either an upper or lower pallet half, each upper and lower pallet half having a plurality of feet, and wherein at least some of the upper pallet half feet are arranged to be opposed to corresponding feet on a lower pallet half, and at least some of the opposed feet are detachably connectable to each other to form a pallet.

Preferably the articles are nestable, and the holder pairs are arranged to release the article(s) in a nested stacked configuration. B2006/003493

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According to another aspect of the invention there is provided a system for moulding a plurality of articles, comprising: a rotational mould apparatus having a plurality of moulds; and means for driving the apparatus between a fill position and an unload position, wherein the spatial position of the apparatus when in the fill position is different to the spatial position of the apparatus when in the unload position.

This aspect of the invention is advantageous in that it is able to mould rotationally a plurality of articles in one apparatus.

Preferably each said mould has at least one mould material inlet on one side thereof, and wherein when the apparatus is in the fill position, the at least one inlet is directed in a generally upward direction and when the apparatus is in the unloading position, the at least one inlet is directed in a generally lateral direction.

Preferably the plurality of moulds are configured for moulding generally planar articles, the moulds having generally planar cavities and being positioned with respect to one another such that the cavities lie on respective generally parallel planes, and wherein the cavity planes are generally vertical when the apparatus is in the fill position, and the cavity planes are generally horizontal when the apparatus is in the unload position. The configurable nature of the apparatus between the fill position and the unload position

Preferably the rotational mould apparatus is rotatable by up to or more than 360° about each of two perpendicular axes.

Preferably the articles are nestable and/or at least one article is a pallet.

Preferably the articles comprise pallet halves, each pallet half being one of an upper or lower pallet half which are connectable to form a pallet. Also preferably each upper and lower pallet half has a plurality of feet on one side thereof, at least some of the upper pallet half feet arranged to be opposed to corresponding feet on a lower pallet half, at least some of the opposed feet being detachably connectable to each other to form a pallet. Further preferably each upper and lower pallet half has a plurality of recesses on a side opposite said one said, each said recess corresponding to a respective one of said feet, such that the feet of the lower pallet half are adapted to nest in the recesses of the upper pallet half to form a nested pair of lower and upper pallet halves.

Preferably there are four pairs of moulds, each said pair comprising one said upper and one said lower pallet half mould. Preferably the moulds are configured such that, when the pallet halves are unloaded, they form a stack of alternating lower and upper pallet halves, the lower most pallet half being a lower pallet half, and the upper most pallet half being an upper pallet half.

Preferably the pallet halves form the stack such that the pallet halves are configured in a stack of nested pairs of upper and lower pallet halves.

Preferably there are two sets of said four pairs of moulds, such that, when the pallet halves are unloaded, they form two said stacks of alternating lower and upper pallet halves.

Preferably the moulds include external heating/cooling means for heating and cooling of the mould using respectively hot and cold oil. Further preferably the external heating/cooling means comprise a heating conduit and a cooling conduit attached to an external surface of each mould.

Preferably the system comprises at least one mould material inlet per mould, such that when the moulds are positioned in the fill position, the inlets are in a substantially uppermost position with respect to sides of the moulds.

Also preferably the system comprises at least one mould material hopper per mould for temporarily storing and releasing mould material into their respective mould cavities via their respective at least one inlets, the hoppers being positionable above the moulds.

Preferably each said mould comprises three inlets arranged to allow entry of mould material into their respective mould cavities. Also preferably the three inlets are on one side of their respective moulds.

Preferably, the moulds are cast aluminium. Alternatively, the moulds are made from super plastic formed aluminium sheets.

Preferably the rotational mould apparatus is arranged to hold the moulds closely adjacent each other during a moulding process and to separate the moulds when in the unload position.

Preferably the system comprises an unloading apparatus according to the above first described aspect of the present invention.

According to another aspect of the present invention there is provided a manufacturing system for manufacturing moulded articles, the system comprising: at least one unit, the unit comprising: at least one article moulding system according to the above described system aspect; and corresponding said article unloading apparatus according to the above described apparatus aspect for unloading articles from a corresponding said article moulding system. 03493

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Preferably the manufacturing system comprises means for supplying mould material to each said mould.

Preferably the supplying means comprises a respective hopper corresponding to each mould and positionable above the at least one article moulding system.

Preferably the supplying means further comprises means for providing each hopper with mould material.

Preferably the manufacturing system comprises automated conveying means for conveying articles formed from a manufacturing cycle of at least one of the units to a storage and/or transport loading means.

Preferably the system comprises a bank of a plurality of said units, and wherein one said conveying means is arranged to convey articles from the manufacturing cycles of each unit. Preferably the bank comprises four said units and wherein one said conveying means is arranged to convey articles from the manufacturing cycles of each unit.

Preferably the system comprises a plurality of banks of a plurality of units, wherein a respective one of a plurality of said conveying means is provided to convey articles from the manufacturing cycles of each unit of a corresponding bank.

Preferably the conveying means comprises a railed trolley. Alternatively, conveyer belt means may be used.

Preferably, when the articles are pallet halves and the unit produces a stack of pallet halves, the lowermost pallet half is a load bearing article for the stack upon the trolley. 6 003493

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Preferably the system comprises a banding means between the unloading apparatus and the storage or transport loading means for banding a predetermined number of articles prior to storage or transport of the articles.

Preferably the conveying means is configured to convey the articles from the unloading apparatus to the banding means prior to conveying the articles to the storage or transport loading means.

According to another aspect of the invention there is provided a manufacturing plant for manufacturing rotationally moulded products from a plastics-based composition, the plant comprising: a composition storage area; a composition loading area, for loading the composition onto delivery means; delivery means for delivering the composition to moulding areas within the manufacturing plant; and moulding areas, each moulding area comprising a plurality of moulding apparatus.

Preferably the plant comprises a storage area for storing the rotationally moulded products.

Preferably each mould comprises means for manufacturing a plurality of products.

According to another aspect of the present invention, there is provided a method of forming moulded polymeric articles, the method comprising the steps of: on an article moulding system comprising a -plurality of moulds, introducing mould material into the moulds; 2006/003493

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after a predetermined time period, opening the moulds; removing the articles from the moulds using an unloading apparatus comprising a support and a plurality of holder pairs, each holder pair being configured to hold at least one article; and moving the respective holders of each said holder pair to release the articles held thereon.

Preferably, the holder pairs are arranged vertically, such that when they are moved to release the articles, a stack of the articles is formed.

Preferably, in the step of moving the holders, the holder pairs are moved sequentially from an uppermost holder pair to a lowermost holder pair, to provide the stack

Preferably, the holders of each holder pair are rotated inwardly with respect to each other to release the article(s) held thereupon.

Preferably, the article includes a pallet or one of an upper or lower pallet half, the upper and lower pallet halves being connectable to form a pallet.

According to another aspect of the present invention there is provided a method of moulding articles, the method comprising the steps of: in a rotational moulding apparatus having a plurality of moulds, positioning the moulds in a fill position; introducing mould material into the moulds; rotating the moulds for a predetermined time period; and positioning the moulds in an unload position, wherein the spatial position of the apparatus when in the fill position is different to the spatial position of the apparatus when in the unload position.

Preferably, each said mould has at least one mould material inlet on one side 03493

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thereof, and wherein when the apparatus is in the fill position, the at least one inlet is directed in a generally upward direction and when the apparatus is in the unloading position, the at least one inlet is directed in a generally lateral direction.

Preferably, the plurality of moulds are configured for moulding generally planar articles, the moulds having generally planar cavities and being positioned with respect to one another such that the cavities lie on respective generally parallel planes, and wherein the cavity planes are generally vertical when the apparatus is in the fill position, and the cavity planes are generally horizontal when the apparatus is in the unload position.

Preferably, during the rotating step, the rotational mould apparatus is rotatable by up to or more than 360° about each of two perpendicular axes.

Preferably, during the rotating step, the moulds are heated to a predetermined temperature for a predetermined time period.

Preferably, the moulds are cooled after being heated and either before or after the moulds are positioned in the unload position.

Preferably, each said mould comprises a heating conduit and a cooling conduit for said heating and cooling, and relatively heated oil is passed through the heating conduit for heating the mould, and relatively cooled oil is passed through the cooling conduit for cooling the mould.

Preferably, the moulds are held closely together when rotating and are moved apart when in the unloading position.

According to another aspect of the invention there is provided a manufacturing facility comprising apparatus for moulding a plurality of pallets, 03493

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apparatus for moulding a container for containing said pallets and means for conveying a predetermined number of said pallets into said container for transport from the facility.

Preferably, each pallet is formed from an upper pallet half and a lower pallet half, the upper and lower pallet halves being connectable to form the pallet.

Preferably, the pallets are conveyed into the pallet in stacks of alternating upper and lower pallet halves, in stacks of upper pallet halves and/or in stacks of lower pallet halves.

Preferably, the apparatus for moulding the pallets comprises the above described system for moulding a plurality of articles.

Preferably, the predetermined number of pallets is the maximum number required to substantially fill the container.

Preferably, the container is a shipping container. Preferably, the shipping container is one of any standard container size, such as 10 foot, 20 foot or 30 foot shipping containers and preferably complies with the International Standard Organisation's standards for shipping containers.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a plan view of a manufacturing plant according to an embodiment of the invention;

Figure 2 is a perspective view of a pallet; 6 003493

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Figure 3 is a side elevation of a stack of upper and lower pallet halves;

Figures 4 to 10 are perspective views of a manufacturing unit comprising an article moulding system and an article unloading apparatus according to another embodiment of the invention, illustrating the mould assembly and the unloading apparatus in various process stage configurations;

Figure 11a is a portioned perspective view of a mould for moulding an upper pallet half;

Figure 11b is an exploded view of Figure 11a; and

Figures 12 to 14 are plan views of alternative embodiments of a manufacturing plant.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring to Figure 1 , a preferred embodiment of the present invention is a manufacturing system for manufacturing polymeric moulded articles, such as pallets. Whereas the manufacturing system is particularly suited to the manufacture of pallets, it will be understood that it is not limited to the manufacture of pallets, but may be adapted for the manufacture of other moulded articles, such as other load bearing articles, other generally planar articles, shipping containers, etc. For convenience, the preferred embodiment will be described with reference to the manufacture of pallets.

A wide variety of shapes, sizes and configurations of pallets may be manufactured using the manufacturing system. Examples are described in

PCT/GB2005/001125, which is incorporated herein by reference. An example of a pallet manufactured by the preferred embodiment of the invention is illustrated in Figure 2. Each pallet 10 comprises upper and lower pallet halves 11,12 connectable to each other to provide the pallet TO. The connection is provided between feet 13 on an under-side surface 14 of the upper pallet half 11 and corresponding feet 15 on an upper-side surface 16 of the lower pallet half 12. The feet 13,15 are hollow, such that recesses 17 corresponding to feet 13 are formed on a bearing surface 18 of the upper pallet half 11 and recesses 19 corresponding to feet 15 are formed on the ground surface 20 of the lower pallet half 12. This provides a convenient means for stacking the pallet halves 11 ,12, as illustrated in Figure 3, where the upper pallet half feet 13 nest in corresponding lower pallet half recesses 19 and vice versa. In this particular embodiment, the configuration of the feet 13,15 and the recesses 17,19 is such that when the lower pallet half feet 15 nest in the upper pallet half recesses 17, the bearing surface 18 is brought closely adjacent the upper-side surface 16. Also, when the upper pallet half feet 13 nest in the lower pallet half recesses 19, the ground surface 20 is not brought as closely adjacent the under-side surface 14. This is evident in Figure 3, illustrating a stack of alternating upper and lower pallet halves 11 , 12. This allows for convenient separation of different numbers of pallet halves.

The manufacturing system illustrated in Figure 1 comprises two banks 21 of four manufacturing units 22. Each unit 22 -comprises a rotational mould system 23 and an article unloading apparatus 24, illustrated in more detail in Figures 4 to 10, for manufacturing polymeric articles in the form of upper pallet halves 11 and lower pallet halves 12, described above. The rotational mould system 23 and article unloading apparatus 24 are controlled by a controller, such as a programmable logic controller {PLC).

A conveyor means in the form of a conveyor 25 is provided for each bank 21 to convey a stack of pallet halves 11 ,12 produced by each unit 22 from the 2006/003493

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units to a banding station 27. A predetermined number of pallet halves 11,12 are banded together at the banding station 27 for storage in a storage area 28 for later transport or directly loaded into standard shipping containers 30 for transport from the plant by truck 31. The movement of the pallet halves 11 , 12 from the banding station 27 may be automated, such as by automatically controlled laser guided forklifts, or by manual forklifs. The number of pallet halves to be banded together will depend on either a particular customer's requirements, or how the banded pallet halves are to be transported. For example, if the banded pallet halves are to be transported by standard 20' (about 6.1m) shipping container, the banding station 27 will band 18 upper pallet halves and 18 lower pallet halves in an alternating nested configuration, since such a banded arrangement of pallet halves is approximately 2.2m in height, and therefore fits conveniently within a shipping container, whose internal height is approximately 2.3m.

The units 22 are positioned in each bank 21 in a staggered array, wherein the unloading apparatus 24 are on a common central line, whereas the positions of the mould systems 23 alternate from side to side along the ^■common central line. Since the footprint and operational area of each mould system 23 is larger than the footprint of each unloading apparatus, the staggering of the positions allows a closer packing density of units 22 per bank 21 , while allowing the unloading apparatus 24 of each bank 21 to use a -common trolley and rail system.

Mould material components for moulding the pallet halves are stored in a material storage area 32. In the present embodiment, the mould material for the pallet halves 11,12 includes polyethylene, a unifier and silicate material, such as sand. The mould material -components are dry-mixed by mixers 34 before being transported to hoppers for feeding into the rotational moulding system, as described in more detail below. Referring to Figures 4 to 10, and 11a,b, each rotational mould apparatus 23 comprises a rotational frame 36 on a manifold 37 for holding two side-by-side groups of eight moulds 40 per group, each mould comprising opposed mould halves 40a,b. The rotational mould apparatus 23, having two side-by-side groups of eight moulds 40, is configured to provide two stacks of eight pallet halves 11,12 includes two opposed mounting plates 42 between which the mould halves 40a,b are slidably mounted on sliding rails 44. The rotational frame 36 is rotatable through 360° about an axis, while the mounting plates 42, rails 44 and moulds 40 are rotatable on the frame 36, on an axis perpendicular to the axis of rotation of the frame.

Each mould 40, for example an upper half pallet mould 40' as illustrated in Figures 11 a, 11b, has a generally planar cavity 53. Each mould 40 is preferably made from cast aluminium and has three inlets {one of which is illustrated in Figure 11b and labelled as reference 46) on one side 48 thereof for the inflow of mould material into the mould's cavity 53. Figure 4 illustrates the rotational mould apparatus 23 in a fill position, where the inlets, located on mould side 48, are directed generally upwardly. Sixteen hoppers (not shown) are provided above each mould apparatus 23, each hopper corresponding to a different mould. The hoppers are configured to provide, gravitationally, a predetermined volume of mould material to their corresponding moulds through the inlets 46. Each mould also comprises a heating/cooling means in the form of hot oil piping and cold oil piping on an external surface of each mould, to control the mould temperature as desired during a moulding process, as described below. The hot oil is heated by gas burners at an oil heating station 50 in the plant, and the cold oil is cooled using a heat exchanger 52. The hot and cold oil is provided to the piping on the moulds 40 via hot and cold oil conduits fluidly communicating with piping on the manifold 37, in turn connected to the piping.

The unloading apparatus 24 is provided to remove pallet halves 11 ,12 from the moulding apparatus 23. The unloading apparatus 24 comprises a support 54, an unloader manifold 55 and a plurality of holder pairs, in the form of pairs of arms 56, 58, rotatably connected to the unloader manifold 55. The pairs of arms 56, 58 are arranged vertically with respect to each other, while the arms 56 and 58 of each pair are horizontally opposed to each other.

More features of the manufacturing units 22 are described below in terms of their use.

Figures 4 to 10 illustrate the manufacturing units 22 at various sequential stages during a manufacturing cycle. At the beginning of each cycle, a controller positions the rotational mould system into a fill position, as illustrated in Figure 4, where the planes of the mould cavities 53 are generally vertical and the inlets 46 are in an upwardly directed configuration. The inlets 46 are therefore in a position to accept mould material from the hoppers. The mould material components are combined in the mixers 34 and conveyed to the hoppers. Once a predetermined volume of mould material is introduced into the moulds, the controller causes the rotational mould system to rotate about two perpendicular axes. At the same time, heated oil is conveyed to the hot oil piping and recirculated between the oil heater 50 and the moulds to heat the moulds to a predetermined temperature, approximately 225°C to 270⁰C, to melt the mould material. The rotation of the moulds 40 distributes the molten mould material through the moulds to form a hollow pallet half. The heated oil is then piped from the hot oil piping and cooling oil is conveyed to the cold oil piping and recirculated between the heat exchanger 52 and the moulds 40. The temperature of the cooling oil is typically ambient, but may be cooled below ambient temperature, for example 1O⁰C, depending on the moulding requirements.

When the pallet halves are sufficiently cooled and set, the controller positions the rotational mould system into an unload position, as illustrated in Figure 5, where the planes of the mould cavities 53 are generally horizontal and the inlets 46 are in a laterally directed configuration. The controller then separates the moulds 40 by causing the moulds 40 to slide apart on the sliding rails 44. At the same time, the mould halves 40a, b of each mould 40 are slid apart to expose the moulded pallet halves 11 , 12, which are retained on the upper one of the mould halves 40a, b, as illustrated in Figure 6. The controller then causes the support 54 to move upon the unloader manifold 55 such that respective pairs of arms 56, 58 are positioned to receive two side- by-side pallet halves 11 , 12, as illustrated in Figure 7. The pallet halves are then released by the upper one of the mould halves 40a, b to their respective pair of arms 56, 58, for example by using a set of ejector pins (not shown) mounted in the upper mould halves 40a,b. The controller then causes the support 54 to withdraw from the rotational moulding system 23 to a release position, as illustrated in Figure 8. The controller then causes the arms 56, 58 of each pair to be rotated inwardly 1218 about axes parallel to the two axes 1220 and 1222 shown in Figure 8, in a sequential manner, from the uppermost pair of arms 56a, 58a to the lowermost pair of arms 56b, 58b. In this way, the release of the pallet halves 11 , 12 is performed in a -controlled manner, ensuring two nested stacks of pallet halves 11 , 12, such as the stack illustrated in Figure 3, are provided. Figure 9 illustrates the half way stage of the sequential arm pair rotation, while Figure 10 illustrates the end of the sequence and of the cycle, where two side-by-side stacks of pallet halves 11 ,12 have been provided upon respective trolleys for conveying to the banding station 27. Two rails, each having at least one trolley, are provided; one rail for each stack produced. In the present embodiment, each cycle is about 20 minutes, but alternatively the cycle may be adapted to be longer or shorter than 20 min.

In the present embodiment of the rotational mould system, the moulds 40 are arranged to provide two side-by-side stacks, each stack having a vertical array of alternating upper and lower pallet halves 11 , 12, where in each stack, the lowermost pallet half 60 is a top pallet half and the uppermost pallet half 62 is a lower pallet half. As would be understood, alternative mould configurations could be used. For example, the moulds may be arranged such that in the resulting stack the lowermost pallet half 60 is a lower pallet half and the uppermost pallet half 62 is an upper pallet half, or all the pallet halves in one or both stacks is a lower pallet half 12, or all the pallet halves in one or both stacks is an upper pallet half 11.

It is also possible to adapt the present embodiment to provide a pallet, or other rotationally moulded article, having a foam filled core. In this alternative embodiment, prior to positioning the rotational moulding system 23 into the unload position, the system 23 is returned to the fill position and core mould material conveyed to the hoppers. The moulds 40 then receive a predetermined volume of core mould material via their respective three inlets 46 from their respective hopper. In this alternative embodiment, the core mould material contains a heat activated foaming agent. Once the core mould material is introduced into the moulds 40, heating oil is provided to the moulds, as explained above with respect to the mould material, to heat the moulds 40 and activate the foaming agent. Once the foaming process is complete and the hollow of the article, or pallet half filled, the mould is cooled as explained above, prior to the controller causing the rotational mould system to rotate to the unload position. The articles are then unloaded as described above.

As will be understood, alternative arrangements of the above described embodiments can be achieved without departing from the scope of the invention. For example, the above described plant embodiment has two banks 21 of four manufacturing units 22 per bank. As will be appreciated, several more units 22 may be added to each bank 21. For example, each bank 21 may comprise up to twenty units 22. Furthermore, there may be more than two banks 21 , for example there may be up to twenty banks 21. The increase in the number of banks may require an increase in the number of conveyors 25, or other appropriate conveying system, per bank, to convey the articles to the banding machine.

In another alternative embodiment, the moulds are super plastic formed aluminium moulds. The cast aluminium moulds of the above described embodiments are approximately 6 to 10 mm in wall thickness. Super plastic formed aluminium moulds are approximately 3 to 4 mm in wall thickness. Therefore, in this embodiment, the moulds are heated and cooled more quickly than cast aluminium moulds. Each manufacturing cycle is therefore reduced from 20min to 15 min.

In an alternative embodiment of the plant, a container moulding system is provided to manufacture a standard shipping-type container for eventual transport of the pallet halves 11,12 from the plant. In this embodiment, the container is manufacture in one area of the plant and conveyed to zone 28 for accepting banded pallet halves therein. Once a predetermined number of pallets has been conveyed into the container, the container is ready to be transported to a predetermined destination.

Figures 12 and 13 illustrate another embodiment of a plant whose features may be used in conjunction with features of the above described plant embodiment. The mould material may be mixed within the plant, or may be mixed and delivered to the plant as raw materials, for example in pellet form. Preferably, the mould material may be formed by mixing the components and forming pellets from the mixed components. Preferably, the unifier may be mixed with the filler before the polymer is added to the mixture.

The plant illustrated in Fig. 12 includes a central container aπea 1110 comprising a plurality of containers 1112, ^each containing a preformed feedstock. A plurality of mobile feedstock machines 1114 obtain a predetermined quantity of feedstock from the central containers 1112 and deliver them to each of a plurality of moulding apparatus 1116.

As illustrated in Fig. 13, the feedstock machines 1210 insert the feedstock into the moulding apparatus 1212. It has been found that it is advantageous to tilt the moulding apparatus 1212 to enable the feedstock to be delivered efficiently to the moulding apparatus 1212. The feedstock machines 1210 are preferably provided with telescopic arms 1214 and telescopic delivery buckets 1216 for delivering the feedstock to the moulding apparatus 1212 along the whole length of the apparatus. This may be particularly advantageous when inserting the second feedstock into the moulding apparatus 1212, since inserting the feedstock along the whole length of the apparatus may enable the feedstock to be inserted more quickly into the apparatus, while the first feedstock is relatively fluid. The telescopic delivery bucket 1216 preferably extends to a length of about 12m, so it may extend the whole length of a container mould, and preferably holds a predetermined amount of feedstock. Preferably, the bucket 1216 is divided into a plurality of sections, each of which holds a predetermined amount of feedstock.

One embodiment of a manufacturing plant may be designed to provide a production output of pallets of around 30,000 pallets per hour {which corresponds to around 715,000 pallets per day, 5,000,000 pallets per week and 250 million pallets per year). Alternatively, such a manufacturing plant may be able to provide around 100 Containers (twenty foot equivalent units, teu) per hour (which corresponds to 2500 teu per day, 17400 leu per week and 870,000 teu per year). The tonnage of raw materials used by such a plant, in thousands of tonnes may be around 0.4 per hour (which corresponds to 10 per day, 70 per week and 3500 per year). A single plant may produce only one type of product or may produce a variety of different products. For example, a single plant could produce both pallets and containers. Another embodiment of a manufacturing plant, whose features may be used in conjunction with features of the above described plant, comprises a plurality of groups of moulds, for example groups of eight moulds, each group being arranged in a bay in the plant. This may allow one set of equipment, for example, one loading truck, to attend to each bay in the plant. The cycle times of the moulds in each bay may be staggered to enable one loading truck to attend to each bay of equipment efficiently.

Two or more loading trucks may be provided for each bay, for example if the product is formed from two or more compositions.

In an alternative embodiment, alternative delivery means may be provided to deliver the required compositions to the moulds. For example a conveyor system may be used to deliver the compositions to the moulds or moulding bay areas.

As described above, each mould is preferably arranged to form a plurality of moulded products. For example a mould the size of a shipping container may be used to form a plurality of pallets, for example around 80 pallet elements may be formed within one mould with 20 elements per -elongate side of the mould. A further eight pallet element may be formed on each end wall of the mould.

In one embodiment, the moulds are heated using a heated oil-based liquid which runs through the mould, preferably close to the surface of the moulding tools. The temperature of the oil-based liquid depends on the Oomposition used to mould the products, but may be around 1400⁰C.

In addition to the bays of moulds, the manufacturing plant may be provided with a loading area in which the loading trucks are loaded with the composition to form the pallets. Two or more loading areas may be provided if two or more compositions are required to form the moulded products.

The composition may be mixed in another area of the plant or may be transported (e.g. shipped) to the plant in a mixed format.

Figure 14 illustrates a schematic diagram of part of a manufacturing plant according to another alternative embodiment whose features may be used in conjunction with features of the above described plant embodiments. Bays containing groups of moulding apparatus, in this case eight apparatus per bay, are arranged within the plant. Storage areas for sand, PE and unifier are also provided and a storage area for storing manufactured products, such as pallets, is preferably provided separately.

While the invention has been described in reference to its preferred embodiments, it is to be understood that the words which have been used are words of description rather than limitation and that changes may be made to the invention without departing from its scope as defined by the appended claims.

Claims

CLAIMS:

1. Apparatus for unloading articles from a moulding apparatus having a plurality of moulds, the unloading apparatus comprising: a support; and a plurality of holder pairs rotatably connected to the support, each holder pair configured to hold at least one said article, wherein the holder pairs are movable to release the artfcle(s) held thereon.

2. The apparatus of claim 1 wherein the holder pairs are arranged to release the article(s) in a stacked configuration.

3. The apparatus of claim 1 or 2 wherein the holder pairs are arranged vertically with respect to each other.

4. The apparatus of any preceding claim wherein the holders in each said holder pair are horizontally opposed to each other.

5. The apparatus of any preceding claim wherein the holders in each said holder pair are arranged to rotate inwardly with respect to each other.

6. The apparatus of any preceding claim wherein the holders of each said holder pair have parallel axes of rotation.

7. The apparatus of any preceding claim wherein the unloading apparatus is arranged such that the holder pairs are rotatable in a sequential arrangement from an uppermost holder pair to a lowermost holder pair, to provide a stack of unloaded articles.

8. The apparatus of claim 7 comprising sequencing means causing the holder pairs to rotate in said sequential arrangement.

9. The apparatus of any preceding claim wherein the moulding apparatus is a rotational moulding apparatus.

10. The apparatus of any preceding claim wherein the respective -cavities of the moulds are generally planar.

11. The apparatus of any preceding claim wherein the holders are arm-like and each extend longitudinally in a common direction from a portion of the support.

12. The apparatus of any preceding claim comprising eight -said holder pairs.

13. The apparatus of any preceding claim wherein each said holder pair is configured to hold two articles side-by-side.

14. The apparatus of any preceding claim wherein the support is movable to move the holder arms between an article retrieval position and an article withdrawal position with respect to the moulding apparatus.

15. The apparatus of any preceding claim wherein the articles are load bearing articles.

16. The apparatus of any preceding claim wherein the articles are pallets.

17. The apparatus of any of claims 1 to 15 wherein each article is either an upper or lower pallet half, each upper and lower pallet half having a plurality of feet, and wherein at least some of the upper pallet half feet are arranged to be opposed to corresponding feet on a lower pallet half, and at least some of the opposed feet are detachably connectable to each other to form a pallet.

18. The apparatus of any preceding claim wherein the articles are nestable, and the holder pairs are arranged to release the article(s) in a nested stacked configuration.

19. A system for moulding articles, comprising: a rotational mould apparatus having a plurality of moulds; and means for driving the apparatus between a fill position and an unload position, wherein the spatial position of the apparatus when in the fill position is different to the spatial position of the apparatus when in the unload position.

20. The system of claim 19 wherein each said mould has at least one mould material inlet on one side thereof, and wherein when the apparatus is in the fill position, the at least one inlet is directed in a generally upward direction and when the apparatus is in the unloading position, the at least one inlet is directed in a generally lateral direction.

21. The system of claim 19 or 20 wherein the plurality of moulds are configured for moulding generally planar articles, the moulds having generally planar cavities and being positioned with respect to one another «uch that the cavities lie on respective generally parallel planes, and wherein the cavity planes are generally vertical when the apparatus is in the fill position, and the cavity planes are generally horizontal when the apparatus is in the unload position.

22. The system of any of -claims 19 to 21 wherein the rotational mould apparatus is rotatable by up to or more than 360° about each of two perpendicular axes.

23. The system of any of claims 19 to 22 wherein the articles are nestable.

24. The system of any of claims 19 to 23 wherein at least one article is a pallet.

25. The system of any of claims 19 to 24 wherein the articles comprise pallet halves, each pallet half being one of an upper or lower pallet half which are connectable to form a pallet.

26. The system of claim 25 wherein each upper and lower pallet half has a plurality of feet on one side thereof, at least some of the upper pallet half feet arranged to be opposed to corresponding feet on a lower pallet half, at least some of the opposed feet being detachably connectable to each other to form a pallet.

27. The system of claim 25 or 26 wherein each upper and lower pallet half has a plurality of recesses on a side opposite said one said, each said recess corresponding to a respective one of said feet, such that the feet of the lower pallet half are adapted to nest in the recesses of the upper pallet half to form a nested pair of lower and upper pallet halves.

28. The system of any of -claims 25 to 27 comprising four pairs of moulds, each said pair comprising one said upper and one said lower pallet half mould.

29. The system of any of claims 25 to 28 wherein the moulds are configured such that, when the pallet halves are unloaded, they form a stack of alternating lower and upper pallet halves, the lower most pallet half being a lower pallet half, and the upper most pallet half being an upper pallet half.

30. The system of any of -claims 25 to 29 wherein the pallet halves form the stack sueh that the pallet halves are configured in a stack of nested pairs of upper and lower pallet halves.

31. The system of any of claims 25 to 30 comprising two sets of said four pairs of moulds, such that, when the pallet halves are unloaded, they form two said stacks of alternating lower and upper pallet halves.

32. The system of any of claims 19 to 31 wherein the moulds include external heating/cooling means for heating and cooling of the mould using respectively hot and cold oil.

33. The system of claim 32 wherein the external heating/cooling means comprising a heating conduit and a cooling conduit attached to an external surface of each mould.

34. The system of any of claims 19 to 33 comprising at least one mould material inlet per mould, such that when the moulds are positioned in the fill position, the inlets are in a substantially uppermost position with respect to sides of the moulds.

35. The system of claim 34 comprising at least one mould material hopper per mould for temporarily storing and releasing mould material into their respective mould cavities via their respective at least one inlets, the hoppers being positionable above the moulds.

36. The system of any of claims 19 to 35 wherein each said mould comprises three inlets arranged to allow entry of mould material into their respective mould cavities.

37. The system of claim 36 wherein the three inlets are on One side of their respective moulds.

38. The system of any of claims 19 to 37 wherein the moulds are cast aluminium.

39. The system of any of claims 19 to 37 wherein the moulds are made from super plastic formed aluminium sheets.

40. The system of any of claims 19 to 39 wherein the rotational mould apparatus is arranged to hold the moulds closely adjacent each other during a moulding process and to separate the moulds when in the unload position.

41. The system of any of claims 19 to 40 comprising an unloading apparatus according to any one of claims 1 to 18 for unloading the articles from the moulds.

42. A manufacturing system for manufacturing moulded articles, the system comprising: at least one unit, the unit comprising: at least one article moulding system according to any of claims 1 to 18; and corresponding said article unloading apparatus according to any of claims 19 to 40 for unloading articles from a corresponding said article moulding system.

43. The system of claim 42 comprising means for supplying mould material to each said mould.

44. The system of claim 42 or 43 wherein the supplying means comprises a respective hopper corresponding to each mould and positionable above the at least one article moulding system.

45. The system of claim 44 wherein the supplying means further comprises means for providing each hopper with mould material.

46. The system of any of claims 42 to 45 comprising automated conveying means for conveying articles formed from a manufacturing cycle of at least one of the units to a storage and/or transport loading means.

47. The system of claim 46 comprising a bank of a plurality of said units, and wherein one said conveying means is arranged to convey articles from the manufacturing cycles of each unit.

48. The system of claim 47 wherein the bank comprises four said units and wherein one said conveying means is arranged to convey articles from the manufacturing cycles of each unit.

49. The system of claim 46 or 47 comprising a plurality of banks of a plurality of units, wherein a respective one of a plurality of said conveying means is provided to convey articles from the manufacturing cycles of each unit of a corresponding bank.

50. The system of any of claims 46 to 49 wherein the conveying means comprises a railed trolley.

51. The system of any of claims 42 to 50 wherein when the articles are pallet halves and the unit produces a stack of pallet halves, the lowermost pallet half is a load bearing article for the stack upon ihe trolley.

52. The system of any of claims 42 to 51 comprising a banding means between the unloading apparatus and the storage or transport loading means for banding a predetermined number of articles prior to -storage or transport of the articles.

53. The system of claim 52 wherein the conveying means is configured to convey the articles from the unloading apparatus to the banding means prior to conveying the articles to the storage or transport loading means.

54. A manufacturing plant for manufacturing rotationally moulded products from a plastics-based composition, the plant comprising: a composition storage area; a composition loading area, for loading the composition onto delivery means; delivery means for delivering the composition to moulding areas within the manufacturing plant; and moulding areas, each moulding area comprising a plurality of moulding apparatus.

55. The plant of claim 54 further comprising a storage area for storing the rotationally moulded products.

56. The plant of claim 54 or 55 wherein -each mould comprises means for manufacturing a plurality of products.

57. The plant of any of claims 54 to 56 wherein the moulding apparatus comprises apparatus according to any of claims 19 to 41.

58. The plant of any of claims 54 to 57 wherein the delivery means comprises means for automatically delivering a predetermined quantity of the composition to the moulding areas.

59. A method of forming moulded polymeric articles, the method comprising the steps of:

-on an article moulding system comprising a plurality of moulds, introducing mould material into the moulds; after a predetermined time period, opening the moulds; removing the articles from the moulds using an unloading apparatus comprising a support and a plurality of holder pairs, -each holder pair being configured to hold at least one article; and moving the respective holders of each said holder pair to release the articles held thereon.

60. The method of claim 59 wherein the holder pairs are arranged vertically, such that when they are moved to release the articles, a stack of the articles is formed.

61. The method of claim 60 wherein in the step of moving the holders, the holder pairs are moved sequentially from an uppermost holder pair to a lowermost holder pair, to provide the stack

62. The method of claim '59, BO or 61 wherein the holders of -each holder pair are rotated inwardly with respect to each other to release the article(s) held thereupon.

63. The method of any of claims 59 to 62 wherein the article includes a pallet or one of an upper or lower pallet half, the upper and lower pallet halves being connectable to form a pallet.

64. A method of moulding articles, the method comprising the steps of: in a rotational moulding apparatus having a plurality of moulds, positioning the moulds in a fill position; introducing mould material into the moulds; rotating the moulds for a predetermined time period; and positioning the moulds in an unload position, wherein the spatial position of the apparatus when in the fill position is 03493

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different to the spatial position of the apparatus when in the unload position.

65. The method of claim 64 wherein each said mould has at least one mould material inlet on one side thereof, and wherein when the apparatus is in the fill position, the at least one inlet is directed in a generally upward direction and when the apparatus is in the unloading position, the at least one inlet is directed in a generally lateral direction.

66. The method of claim 64 or 65 wherein the plurality of moulds are configured for moulding generally planar articles, the moulds having generally planar cavities and being positioned with respect to one another such that the cavities lie on respective generally parallel planes, and wherein the cavity planes are generally vertical when the apparatus is in the fill position, and the cavity planes are generally horizontal when the apparatus is in the unload position.

67. The method of any of claims 64 to 66 wherein during the rotating step, the rotational mould apparatus is rotatable by up to or more than 360° about each of two perpendicular axes.

68. The method of any of claims 64 to 67 wherein the article includes a pallet or one of an upper or lower pallet half, the upper and lower pallet halves being connectable to form a pallet.

69. The method of any of claims 64 to 68 wherein during the rotating step, the moulds are heated to a predetermined temperature for a predetermined time period.

70. The method of any of claims 64 to ^*69 wherein the moulds are cooled after being heated and either before or after the moulds are positioned in the unload position.

71. The method of claim 69 or 70, when appended to claim 69, wherein each said mould comprises a heating conduit and a cooling conduit for said heating and cooling, and relatively heated oil is passed through the heating conduit for heating the mould, and relatively cooled oil is passed through the cooling conduit for cooling the mould.

72. The method of any of claims 64 to 71 wherein the moulds are held closely together when rotating and are moved apart when in the unloading position.

73. The method of any of claims 64 to 72 wherein the articles are unloaded according to the method of any of claims 59 to 63.

74. A manufacturing facility comprising apparatus for moulding a plurality of pallets, apparatus for moulding a container for containing said pallets and means for conveying a predetermined number of said pallets into said container for transport from the facility.

75. The facility of claim 74 wherein each pallet is formed from an upper pallet half and a lower pallet half, the upper and lower pallet halves being connectable to form the pallet.

76. The facility of claim 75 wherein the pallets are conveyed into the pallet in stacks of alternating upper and lower pallet halves, in stacks of upper pallet halves and/or in stacks of lower pallet halves.

77. The facility of any of claims 74 to 76 wherein the apparatus for moulding the pallets comprises the system of any of claims 19 to 41.

78. The facility of any of ^claims 74 to 77 wherein the predetermined 493

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number of pallets is the maximum number required to substantially fill the container.

79. The facility of any of claims 74 to 78 wherein the container is a shipping container.

80. An unloading apparatus, a moulding system, a manufacturing system or a manufacturing plant substantially as herein described with reference to the accompanying drawings.