The present invention relates to structures for insulating kiln cars-

Kiln cars are used to carry unfired articles through and into kilns, to fire the articles. Outside the kiln, the kiln car is loaded with kiln furniture and articles to be fired, and is then moved through or into the kiln. After emerging, the fired articles are removed. The kiln car can then be reloaded and sent again through or into the kiln. Typical kiln constructions have permanent walls and a roof, the floor being formed by a train of kiln cars extending along the whole length of the kiln. Thus, a fully insulated kiln is achieved. However, each kiln car is raised to the maximum temperature in the kiln, and then cools after leaving the kiln, while it is being unloaded and reloaded. The car again heats up when re-entering the kiln. The heat which is lost each time a kiln car cools off can represent a significant heat loss in the system, possibly the main loss. In order to combat this loss, various proposals have been made for insulating kiln car bases by using low thermal mass material, such as ceramic fibre. However, a problem arises, because ceramic fibre

is not sufficiently strong to carry the weight of the load on the kiln car without being crushed. One proposal therefore uses hollow refractory blocks to provide the necessary strength, and filled with low thermal mass material. Another proposal uses a complicated construction of interlocking slabs of refractory material to form hollows for the fibre and to provide a tiled surface for supporting the load on the car. A third proposal uses a layer of convoluted ceramic fibre blanket which is held under compression and drilled to allow refractory pegs or pillars to be inserted through the blanket to stand on the kiln car base and support the weight of kiln furniture and articles to be fired. This proposal is only suitable for light loads.

The proposals which use hollows formed by refractory material still require a significant proportion of the insulating structure to be refractory material, which has a significantly higher thermal mass than ceramic fibre for instance. The structures are complicated to assemble and install. It may be necessary for the structures to be installed on-site. This contributes to the cost of the structures in two ways. Firstly, the manufacturer is required to attend at the site of the kiln, rather than performing the bulk of the manufacture at his own premises. Secondly, the operation

of the kiln is disrupted during construction, thereby reducing the output of the kiln.

The present invention seeks to provide a kiln car insulating structure which is superior to known structures.

According to the invention there is provided a kiln car insulating structure comprising a support surface, which may bear the weight of articles to be carried into a kiln by a car, and a plurality of load transfer members each having a height which is at least as great as the thickness of insulating material to be placed on the support surface, and providing upper surfaces whose lengths are great in comparison with their widths, the load transfer members being supported at their lower extremities by the support surface and being distributed across the support surface to locate the upper surfaces at boundaries between regions which are filled with low thermal mass insulating material, the upper surfaces of the load transfer members forming elongate surfaces on which articles to be carried may rest, whereby, in use, the weight of articles being carried is transmitted through the load transfer members to the support surface without being applied to the insulating material.

Preferably the regions of insulating material are wholly separated, one from another, by load transfer members. The load transfer members may provide elongate surfaces which extend wholly across the structure. Each elongate surface is preferably provided by a single load transfer member. The load transfer members may be arranged to have their upper surfaces running parallel to each other. They may be of parallelepipedal form.

Preferably at least some of the load transfer members are fixed in position on the support surface. Any load transfer members which are not fixed in position on the support surface may, in use, be held against movement by the presence of insulating material in the said regions. The insulating material may be under compression in the said regions. Preferably the load transfer members hold the insulating material under compression. The insulating material may be ceramic fibre. The insulating material may be in the form of slabs, con oluted blanket, or layered blanket.

The insulating material may be exposed between adjacent load transfer members, and exposed surfaces of the insulating material are preferably treated to contain the insulating material in the regions. The insulating material may be ceramic fibres treated with sealant. The

insulating material may overhang at least one edge of the support surface and be profiled to form a heat seal.

The load transfer members may be of refractory material .

The structure may further comprise connection means operable to connect the insulating structure to another similar insulating structure to provide a larger composite insulating structure.

The support surface is preferably the upper surface of a generally planar member. The support surface may be adapted to be attached to or form part of a kiln car.

One embodiment of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawing which is a schematic perspective view of the structure.

The drawing shows a structure for use in insulating a kiln car. The structure comprises a support surface 10 which may bear the weight of articles to be carried into a kiln by the car. A plurality of load transfer members 12, 14 each have a height which is at least as great as the thickness of insulating material above the support

surface 10. Each load transfer member has an upper surface 20 whose length is great in comparison with its width. The load transfer members 12, 14 have their lower extremities supported by the support surface 10 and are distributed across the support surface to form boundaries between regions 16 which are filled with low thermal mass insulating material 18. The upper surfaces 20 of the load transfer members 12, 14 are located at the boundaries and are exposed to form elongate surfaces on which kiln furniture or other articles (shown schematically at 22) may rest. Thus, in use, the weight of the articles being carried is transmitted through the load transfer members 12, 14 to the support surface 10, substantially without being applied to the insulating material 18.

In more detail, the support surface is provided by a base sheet or frame which forms part of a conventional kiln car or is provided with appropriate fixings or mounting points to allow it to be attached to a conventional kiln car or kiln car bogey. The surface 10 will be an upper surface of the assembled kiln car.

At locations spaced across the support surface 10, pairs of angle iron strips 24 are attached to the support surface 10 to form between them channels for receiving

the lower edge of a respective load transfer member 12. The spacing of the strips 24 corresponds to the width w of the members 12, which are all generally parallelepipedal in form. The strips 24 firmly fix the members 12 in position on the support surface. The strips 24 are all parallel, so that the members 12 are also held parallel to each other. The members 12 preferably extend wholly across the support surface 10. Alternatively, several members 12 could be aligned end to end to extend across the surface 10, or ot ier arrangements of members 12 could be used. Each member is preferably a single unitary member but could be formed from a plurality of smaller elements attached together in an appropriate manner.

In the arrangement shown, when the members 12 are all parallel and each extends wholly across the surface 10, the insertion of a member 12 in each channel formed by strips 24 divides the top of the structure into a plurality of regions 16 which are wholly separated from each other by the members 12. These regions are filled with low thermal mass insulating material 18, such as ceramic fibre blanket or slab, preferably under compression. For instance, the fibre may be compressed and held under compression by bands before being located in the region 16. Thereafter the bands can be cut and

removed. The insulating material 18 can then expand to fill the region between members 12, but remain under compression.

The insulating material 18 has exposed faces 26 at the ends of the regions between the members 12. Containment of the insulating material 18 is completed by treating the faces 26, for instance by coating with a ceramic fibre sealant. The insulating material 18 can, if desired, be extended to overhang the edge of the surface 10, as indicated at 28. The overhanging portion 28 can be profiled to form a heat seal which cooperates with a complementary channel in the wall of a kiln. Ceramic fibre insulating material is easy to shape and can be "worn" to shape by sending the structure through the kiln to wear away any excess material in the overhanging portion 28. This allows a closer fit between the portion 28 and the complementary channel, than would be possible with hard, rigid seal material.

The overhanging portion 28 can be a separate bar of insulating material attached to the side of the structure and extending substantially wholly along it.

The regions 16 may be further sub-divided by the use of additional load transfer members 14 identical with

the members 12, but not located between strips 24 at their lower edge. These members 14 are therefore not fixed to the support surface, but are supported by it and are held against movement by the presence of the insulating material, especially when the insulating material is under compression. The compression will also serve to retain members 12, 14 in position even if they break, or if the strips 24 become broken or detached from the surface 10.

The members 12 and the members 14 are refractory material. This has worse insulating properties than the ceramic fibre 18, but sufficient mechanical strength to allow it to support weight, whereas the ceramic fibre 18 would be crushed by the direct application of even a small downward force. The'elongate nature of the members 12, 14 enhances their stability. The length 1 of the members 12, 14 is many times greater than the width w. Typical dimensions for the members 12, 14 are:

Height (h) : 150 mm Width (w) : 13 mm Length (1) : 300 mm

The spacing between adjacent members 12, 14 may be 150 mm, and members 12, 14 are preferably arranged

alternately as shown in the drawing.

In use, the structure described above supports kiln furniture and articles to be fired in the following way. The kiln furniture 22 is positioned to span the gap between at least two members 12, 14, and is then placed on those members to be supported by their upper surfaces. The elongate nature of the surfaces 20 allows the furniture to be at any point along the length of the members 12, 14. Once the kiln furniture 22 has been laid on the members 12, 14 in this way, the articles to be fired may be placed on the kiln furniture 22 in the normal way. The weight of the kiln furniture and articles is then borne directly by the members 12, 14 and transmitted through them to the support surface 10. No part of the weight is applied to the insulating material 18, because the height h of the members 12, 14 is sufficient for the upper surfaces 20 of the members 12, 14 to be level with or above the upper extremities of the insulating material 18.

The structure which has been described allows full loads to be carried but is a structure which is predominantly of low thermal mass material. The structure may be 90?ό low thermal mass material. The structure therefore simultaneously achieves adequate load

support properties, low thermal mass and high insulation properties .

The structure may be manufactured in a single unit for installation on a kiln car, or may alternatively be manufactured in smaller sections, a plurality of which are placed side by side to cover the top of the kiln car. The latter arrangement has the additional advantage that the smaller units can be sufficiently small to be conveniently transported, so that they can be manufactured off-site, transported to the site and quickly assembled to complete the insulation of the kiln car. This minimises the work required on-site, thereby reducing the expense referred to above. When units are to be used together in this way, it may be appropriate to provide means for connecting adjacent units together, in addition to means on each unit for attaching that unit to the kiln car.

It will be apparent that many variations to the apparatus described above may be made without departing from the spirit and scope of the present invention. Any conventional low thermal mass insulating material can be used. Alternative structures can be used for fixing the members 12 on the surface 10, in place of the strips 24. Indeed, such fixing means could be omitted entirely, if

the insulating material is to be retained under compression, and some alternative means for doing so are provided.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the. drawings whether or not particular emphasis has been placed thereon.