TECHNICAL FIELD OF THE INVENTION The object of the invention are methods and arrangement for producing a fireplace, a mould and a fireplace according to the preambles of the independent claims presented below.

PRIOR ART Fireplaces and quite particularly structurally rather complicated heat accumulating fireplaces are generally produced from elements cast for this purpose, which elements are assembled and joined to each other at the building site to form a fireplace. Heat accumulating fireplaces are mainly comprised of an outer shell, a possible inner shell and additionally a core. Numerous elements of various shapes are needed for the assembly.

Said elements are usually cast in a centralized manner in a production plant, where there is for this purpose a large number of moulds for each element of the furnace types that are in production. The moulds are either metallic or wooden. The metallic moulds are expensive and heavy but their operational life is long. The wooden moulds are cheaper and lighter but they have to be replaced from time to time. The investment costs of the moulds become high because there are usually several furnace types, each furnace type requires many elements of different shapes, the hardening of the cast elements as well as their removal from the moulds and the cleaning of the moulds take a lot of time, and a sufficient production capacity requires that there are a lot of moulds.

In the production plant, the elements are cast of a casting compound. The casting compound can be manufactured for example by mixing water and for example finely divided ferrochromium slag as well as aluminum cement in a mill. The ingredients react with each other generating heat, which for its part accelerates the hardening reaction. Typically, at least in the winter, the casting has to be carried out indoors so that the casting compound will not cool down too fast and

that the hardening time will not prolong unreasonably or that the hardening will not be incomplete. Cast elements cannot be removed from the moulds and be moved to a warehouse or be delivered before the casting compound has hardened, which will take time and the mould is occupied during this time.

It is also known to use a stiffer casting compound that hardens faster. In this case, the compound is cast to the moulds in the production plant on a special vibrating table. Thanks to the quickly drying casting compound, the elements can be removed from the moulds relatively quickly.

In order to keep the investment and storage costs as well as the number of the moulds within reason, the purpose is generally to use as large moulds as possible, i.e. to produce as large elements as possible. However, the size of the mould is limited by its weight as well as the weight of the component to be cast, as they have to be able to be lifted with manpower.

If stored outdoors, the cast elements are exposed to weather effects, for example frost damages. The elements are vulnerable to nicks when lifted and moved. Thus it has to be attempted to protect the elements during storage and transport.

Gathering the several different elements needed for one fireplace at the plant for transport requires considerably work and carefulness.

Correct assembly of the fireplace at the building site is difficult. Often a bricklayer has to choose the necessary part solely on the basis of the form of the element. Defects occur easily in the assembly. Defects in the structure of the fireplace can be dangerous and it is difficult to correct the defects made.

Some solutions of the prior art are disclosed in the publications GB 1441334, FR 2469524, GB 1302021 and DE 1975942 U.

THE AIM AND BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is to reduce or even to eliminate above described problems appearing in the prior art.

An object of the present invention is to provide a solution with which the production and the assembly of fireplaces made of cast elements become faster, easier and cheaper than before.

An object of the present invention is to provide a solution with which construction defects of fireplaces are reduced.

In order to realize the objects mentioned above, among other things, the present invention is characterised by what is presented in the characterising parts of the enclosed independent claims.

The embodiments and advantages mentioned in this text relate, when applicable, as well to the methods, arrangement, mould as to the fireplace according to the invention, even though it is not always specifically mentioned.

A typical mould according to the invention for casting elements of a fireplace, particularly a heat accumulating fireplace, comprises a bottom and partition walls. The partition walls define within the mould at least two open cast spaces that are separate from each other. In a typical mould according to the invention, the cast spaces have substantially the same height. That the cast spaces have substantially the same height means that the elements to be cast in the mould will have substantially the same height.

In a typical method for producing a fireplace according to the invention, at least two fireplace elements of the same height, belonging to the same fireplace, are cast in one mould.

A typical fireplace according to the invention is produced so that several cast elements are laid on top of each other to several layers and thus fireplace walls

and channels in between them are formed. Typically, the elements are fixed to each other with a known heat-resistant compound. Each layer is formed of one or more cast elements. The elements forming each one layer have substantially the same height. The elements forming each one layer are laid substantially to the same height in the finished fireplace. That the elements of one layer have substantially the same height means that there can be slight alterations in height. Preferably, the elements of one layer and thus also the layer formed of them are as much of the same height as possible. In an embodiment of the invention, each of the fireplace layers that are formed of cast elements has the same height.

That the elements to be cast in the mould have the same height makes it possible to simplify the production. Moulds having the same height are easy to store on top of each other. If several layers have the same height, it is possible to use the same equipment for different moulds. At the same time, it is possible to use the same mould for producing even different layers with minor modifications. In other words, the number of different moulds and mould tools needed is small. With the present invention, a more economical way to cast elements of a fireplace, and quite particularly of a heat accumulating fireplace, is provided. Furthermore, the transport of the already cast elements and their assembly into a fireplace become easier.

The layers can have a height of for example approximately 80 mm or 70 to 100 mm or 50 to 150 mm. With this kind of layer height, several different fireplace structures are easily provided.

When a fireplace that is assembled of cast elements is mentioned in this text, it is meant that a fireplace body comprising walls and smoke flues in between them is produced of the cast elements. Usually, the fireplace body is further covered with for example tiles or plaster. Usually, suitable accessories, such as dampers and ash box doors, are attached to the body.

In an embodiment of the invention, the elements are not of conventional clay brick. Preferably, the elements are typically of some refractory castable material.

In an embodiment of the invention, the casting compound comprises cement, for example at least 5 %, 10 %, 15 %, 20 %, 25 %, 30 %, 35 %, 40 %, 45 % or at least 50 % of the mass of the casting compound. Cement can also form for example 5 to 75 %, 5 to 50 %, 5 to 25 %, 10 to 75 %, 10 to 50 %, 10 to 25 %, 15 to 75 %, 15 to 50 %, 15 to 25 %, 25 to 75 % or 25 to 50 % of the mass of the casting compound.

In an embodiment of the invention, the elements are cast of a casting compound that comprises water, ferrochromium slag and aluminum cement. The composition of the compound can of course vary according to need. In an embodiment, the ingredients of the casting compound are mixed before the casting in a mill.

In an embodiment of the invention, each of the fireplace layers that are formed of two or more cast elements has the same height. Usually, especially the structure of the so-called heat accumulating fireplaces requires several elements within each other. It is often sensible to produce structurally more complicated layers of several elements that are tightly sealed together after assembly. Often it is worthwhile to produce a layer of several elements also because the elements are then lighter and easier to handle.

Some fireplace layers, such as the base plate of the fireplace, the ceiling, i.e. the cap of the fireplace or the layer immediately below the ceiling of the fireplace, can be formed of one element, even though the main part of the layers were made of two or more elements. The base plate and ceiling of the fireplace or some other fireplace layers can also be formed to have a height different from the height of the main part of the layers.

In an embodiment of the invention, each layer is formed of at the most ten, preferably at the most six or at the most three cast elements. Usually, the structure of the fireplace is made suitable and the elements are made to have a suitable weight with two, three, four, five or six elements per layer.

In an embodiment of the invention, the main part of the fireplace layers are formed of at least two cast elements. The main part means here that there are only a few fireplace layers formed of one element, for example one, two, three, four or five. Thus, of all layers, for example less than 25 %, less than 20 %, less than 15 %, less than 10 %, less than 5 % or 0 to 20 % of the fireplace layers are formed of one element.

In an embodiment of the invention, at least two fireplace elements destined to the same layer, i.e. to the same height of the finished fireplace, are cast in one mould. In this way, the parts destined to the same layer are readily in the same place, which makes the assembly of the fireplace easier.

In an embodiment of the invention, the elements forming the core of the fireplace and the outer shell surrounding it are cast in one mould.

In an embodiment of the invention, one whole layer of the fireplace is cast in one mould. By this is meant that all elements destined to one layer of the fireplace are cast in one mould. Thus, the production is further simplified. In this way, the assembly of produced elements is simple and defects in the assembly of the fireplace are reduced.

In an embodiment of the invention, several layers of one and the same fireplace are cast in several moulds so that, when laid in a certain order on top of each other, they form all cast walls of a finished fireplace and channels in between them.

In an embodiment of the invention, several moulds are stacked on top of each other for example on a pallet. This can be done for example so that when the first mould has been laid on the platform, it is filled with casting compound. A second mould is then laid on top of the first mould, and it is filled with casting compound. By casting in this way, the moulds form a stack. In an embodiment of the invention, the hardening of the elements mainly takes place in said stacks. Then, care has to be taken that the required ventilation channels are left between the

moulds. For example, recesses extending to the outside of the stack of moulds can be arranged on the upper and/or lower surfaces of the moulds in order to arrange for the ventilation between the moulds.

One stack can contain for example 6 to 8 or 6 to 10 or 5 to 12 moulds on top of each other. The finished fireplace can contain for example 20 to 30 layers. Of course, the height of the layers and of the fireplace may vary according to the needs at hand.

In an arrangement according to the invention, moulds containing several elements belonging to the same fireplace have been stacked on top of each other such that at least most moulds of the stack contain one whole layer of the fireplace, i.e. all elements destined to one layer of the fireplace. In an embodiment of the invention, most moulds contain at least two fireplace elements of the same height, belonging to the same fireplace. An arrangement of this kind makes the assembly of the fireplace easier.

In an embodiment of the invention, the moulds are stacked on top of each other in the order of assembly work of the fireplace.

In an embodiment of the invention, when casting, the moulds are stacked on top of each other to the same order as their position in the finished fireplace. That is, the moulds are typically stacked so that the moulds containing the elements that are needed last when assembling the fireplace are placed on top of the stack. This is preferable especially if after transport to the assembly site of the fireplace, the moulds are first unloaded from the pallet to a new stack having the inverse order as compared to the original stack, and the moulds are only thereafter separated from the cast elements. Then, the assembly of the fireplace is particularly easy.

In an embodiment of the invention, when casting, the moulds are stacked on top of each other to the inverse order as compared to their position in the finished fireplace. That is, the moulds are typically stacked so that the moulds containing

the elements that are needed first when assembling the fireplace are placed on top of the stack. This is preferable especially if the moulds are separated from the cast elements only at the fireplace assembly site. Then, the assembly of the fireplace is particularly easy.

In order to make the assembly easier, a marking can be formed on the outer surface of the mould which marking tells the position of the elements contained in the mould in the finished fireplace. For example, the mould may contain fixing means for a piece of paper or an adhesive label. Or the mould may contain a tablet suitable for a marking made by a pen.

The mould according to the invention may be disposable or reusable. Disposable moulds can be made of a cheap raw material and their investment and labour costs are low as compared to metallic or wooden moulds. A disposable mould can, however, be made dimensionally very accurate, which makes the assembly of the fireplaces easier and improves their quality. The disposable mould according to the invention can for example be of a suitable plastic material, such as expanded cellular plastic, preferably for example expanded polystyrene. The disposable mould can protect the elements up to the building site of the fireplace. There it is easy to remove from around the elements. An advantage of disposable moulds is that the casting can be performed at the fireplace building site whereby the elements need not be transported. Even though the casting was performed in a centralized manner, an advantage of the disposable moulds is that they need not be washed after use and the elements can be produced economically to the size in which their handling is easy.

A mould made of a plastic material can easily be made watertight. Then, the water needed for casting cannot drain away from the mould. This improves the quality of the elements to be cast. A mould made of a plastic material, such as expanded polystyrene, can be made to be well heat insulating. Good heat insulation fastens the drying process.

If in the production of the plastic mould, before forming the mould, a suitable additive, such as a dye, is added to the plastic raw material, the additive will adhere to the surface of the plastic raw material. Such an additive makes the surface of the finished mould slippery so that the dried cast element detaches easily from the mould. A suitable additive in the mould can thus replace the presently used mould oils. Thus, the production speeds up. The additive can for example be suitable oil or some other suitable fat-soluble substance. This method is suited for the production of moulds made of for example expanded polystyrene. This method is suited for the production of moulds to be used in various casting processes, particularly in casting processes of cement-based substances.

A reusable mould can be made of for example wood, metal or a suitable plastic material. If a casting compound is used that is quickly after casting sufficiently stiff, it is possible to detach the elements of the fireplace from such mould quite quickly after casting. In this kind of process and equipment, a so-called vibrating table can be used in a known manner, or the casting can be performed by compressing.

In an embodiment of the invention, the moulds are at first similar and comprise partition walls and cast spaces in between them. Before casting, at least some of the moulds are then modified either by removing partition walls or parts thereof from the moulds or by adding partition walls or parts thereof to the moulds. In this way, the shape of the cast spaces is altered, whereby also the shape of the elements produced in the modified moulds changes. In this way, several different elements are easily provided with one basic mould.

Partition walls or parts thereof can be removed e.g. by cutting with a hot-wire cutter. The partition wall to be added can for example be a plastic or metallic plate of a suitable size that is pressed tightly to the mould so that in its place of location it obstructs a cast space in the mould. With the help of a partition wall to be added, large elements can be divided into smaller elements whereby their handling becomes easier.

If such mould is made of a suitable material that can easily be moulded, it is easy to perform said modification quickly. Such mould is preferably disposable and made of for example expanded polystyrene. It is easy to remove the desired partition walls or parts of partition walls from materials of this kind. On the other hand, it is possible to press a partition wall to be pressed to an easily mouldable material tightly to its place.

In an embodiment of the invention, on the upper surface of at least some of the partition walls defining the cast space and at the corresponding point on the lower surface of the bottom of the mould there are interlocking means, such as recesses and/or protrusions fitting with them. After casting, the locking means of two moulds stacked on top of each other thus are faced towards each other, whereby the alignment of the moulds becomes easier. With the same protrusions, it is also possible to reinforce the walls of the mould.

In an embodiment of the invention, on the bottom of at least some of the cast spaces, there is at least one recess and at the corresponding point on the lower surface of the bottom of the mould, there is a protrusion. Thereby projections and recesses fitting with them are formed to the elements, facilitating the alignment of the elements to be stacked on top of each other when assembling the fireplace.

In an embodiment of the invention, on the outer surfaces that are opposite to the surfaces facing the casting or the outer castings, there are bosses in order to stiffen and to reinforce the walls of the mould.

BRIEF DESCRIPTION OF THE FIGURES

In the following, the invention will be described in more detail with reference to the appended schematic drawings, in which

Figure 1 presents a perspective view of a preferred embodiment of the invention with which it is possible to cast elements of different heights and different shapes belonging to any element layer of the fireplace at the same time and in the same mould by removing, if

need be, partition walls and/or adding loose transverse partition walls and Figure 2 presents a perspective view of the mould of Figure 2 from below, and Figures 3 to 9 present different building stages of a body of a fireplace according to the invention.

DETAILED DESCRIPTION OF THE EXAMPLES OF THE FIGURES

Figures 1 and 2 present a mould according to the invention that is marked generally with reference numeral 1. It is formed of outer walls 2 and of several inner walls that are marked generally with reference numeral 3. The walls 2 and 3 form several cast spaces 4, 40, 41 between them. A bottom 5 covering the whole mould defines from below the cast spaces. There are bosses 7 on the lower surface of the bottom in order to stiffen and to reinforce the mould. Thanks to the bosses 7, a gap is left between the moulds 1 stacked on top of each other, which makes it possible to organize ventilation that is advantageous to the drying of the elements. By grabbing from the gap formed by said bosses 7, it is easy to lift even stacked moulds from each other. In Figure 2, several circular traces 29 can be seen, which traces have come up during the production process of the mould.

In order to facilitate the building of the fireplace, moulds 1 can be equipped with markings facilitating the building, and in the mould presented in the drawing, such marking can be made or attached e.g. to the flat outer corner surface 8 in which the marking can be seen even though moulds 1 had been stacked on top of each other.

The casting of the element is performed to the cast spaces 4, 40, 41 presented in the drawing, to the level of the upper surface of the mould. Before casting, a release agent making the detachment of the element easier, for example mould oil, can be applied to the inner surfaces of the cast spaces 4, 40, 41. When the mould has been produced of expanded cellular plastic, such as expanded polystyrene, the reaction heat of the casting compound cannot escape much but remains there to fasten the hardening reaction. The mould 1 can be covered e.g.

by stacking moulds with their cast elements on top of each other. After the casting compound has hardened, the mould is detached from it by peeling the mould that can be broken off as pieces from around the element. After use, the moulds made of expanded polystyrene or other plastic material can be utilized for example by burning.

The casting to the mould 1 can be performed either in a centralized manner in production plant destined to this purpose, in which case the moulds with the elements contained in them are transported to the fireplace building site, or else the casting can be performed at the building site of the fireplace(s), making in fact the whole production plant unnecessary. In the latter case, a client needs to order only the moulds and to purchase the materials needed for casting and to rent the equipment, such a mixing mill.

All elements for the fireplace can be cast from mould 1 , if need be, by removing and/or adding partition walls 3. The structure of the mould 1 must have been designed carefully so that all elements of the body of one fireplace can be obtained from cast spaces of different shapes by combining or dividing them. The mould is preferably realized so that the elements needed for each element layer of the fireplace can be cast together and in the same mould 1 , when partition walls 3 have first, if need be, been removed and/or added. Often, it is preferable to perform the castings so that the casting of the lowest layer of the fireplace is performed first and then one proceeds layer-by-layer upwards. The empty mould 1 is laid on top of the previous cast mould and it is filled with casting compound. This continues until all elements needed for the fireplace have been cast. To one stack, for example approximately 6 to 10 moulds can be laid on top of each other. After the casting compound has dried sufficiently, the fireplace cast in the moulds is transferred either to a warehouse or onto the platform of a delivery vehicle to be transported to the building site. At the fireplace building site, the moulds are unloaded to a new stack after the elements have already hardened. In this new stack, the moulds and the elements contained in them are in the inverse order as compared to the position of the elements in the finished fireplace. In this way, the

assembly can be performed by always taking in order the topmost mould 1 with its elements from the stack.

There are recesses 10 on the upper surface of at least some walls, preferably the outer walls 2, of the moulds 1 and protrusions 10' at the corresponding points on the lower surface of the bottom 5 of the moulds in order to facilitate the alignment of the stackable moulds 1. Furthermore, said protrusions and recesses reinforce the walls during casting and transportation.

The casting of the fireplace elements is begun by casting its base plate. For this purpose, all partition walls are removed from the mould 1 so that only the outer wall 2 defining the bottom 5 remains in its place. However, if elements are cast for a fireplace to be located in a corner, the skew corner partition walls 21 , 21' are left in their place.

The elements forming the core of the fireplace are cast to the cast space 41 , from which spaces have been separated for flue gas ducts by partition walls 20 and 20'. In the fireplace to be assembled, there are two pairs of flue gas ducts, the inner duct for downwards flowing flue gases and the outer duct for upwards towards the chimney flowing flue gases. Transverse partition walls 23 are removed from the moulds 1 with which elements forming the core are cast to the layers below and above the furnace doors. Then the cast space 41 ' unites with the cast space 41. In the layers at the level of the furnace doors, the transverse partition walls 23 are left in their place, whereby the casting of the elements forming the core takes place only in the cast space 41.

The elements forming the outer shell of the fireplace are cast to the cast space 40 surrounding the cast space 41 of the element forming the core. The cast space of the elements forming the outer shell and destined to the element layers at the level of the furnace doors, however, are further limited by adding to the cast space 40 transverse partition walls 22 (presented with broken lines in Figure 2). The location of the partition walls 22 can be chosen according to the desired size of the furnace door. In order to form an opening for the ash box, additional partition

walls 32 and 33 can be placed in the cast spaces 40 and 41 '. In this case, a part of the partition wall 35 is removed between partition walls 32 and 33.

The fireplace may also contain one or more shelves above and/or below the furnace door, in which case the shelf is cast as an integral part of the outer shell element on the same level. For this purpose, the outer partition wall 24 of the cast space 40 is removed. If a shelf extending from wall to wall all the way across the outer surface of the fireplace is desired, also the partition walls 25 and transverse partition walls 27, extending from the partition wall 24, will have to be removed. As to the fireplace to be located against a straight wall, each partition wall 26 extending from the partition wall 25 as well as skew corner partition walls 21 , 21' can also be removed. If partition walls 28 are additionally removed, the corners of the shelf will become rectangular.

Finally, the topmost fireplace layer, i.e. the lid or the cap, is cast by removing all partition walls from the mould preform 1 , just like before the casting of the base plate.

It is evident to a man skilled in the art that the scope of protection of the invention may vary within wide boundaries and that the above presented are merely examples of the numerous embodiments of the invention.

Thus, for example the transverse partition walls of the described mould can be left out, if so desired, or added, if need be, or alternatively removed, if need be, if the mould preform contains them.

Instead of mould preforms, a tailored mould can be used for each element layer of the fireplace, whereby no partition walls need to be removed nor transverse partition walls be added. This will increase the investment costs, as a separate mould tool is needed for producing each individual mould for casting the element(s) of each element layer of the fireplace, whereas one mould tool is sufficient for producing mould preforms. On the other hand, the amount of work

decreases, as there is no need to remove the partition walls from or to add them to the tailored mould.

The mould according to the invention can also be realized so that an integral partition wall structure containing all partition walls needed for the element layer in question is pressed from above to an empty mould. As a partition wall structure, a partition wall structure preform can be used that contains all partition walls needed for the casting of the element layers, the partition walls being removed at need before fitting the structure to the basic mould. The removal is easy when the partition wall structure preform is separate and before it is fitted to the basic mould.

Figures 3 to 9 present different building stages of a body 100 of a fireplace according to the invention. All elements shown in the Figures have been formed in the mould according to the invention. The moulds for each layer have been produced always in one mould at the time. For the sake of clarity, corresponding elements of different layers have the same reference numerals. All different layers are not shown. It is evident that in the fireplace according to the invention, the walls and the channels in between them can always be formed at need.

Figure 3 shows a base plate 41. The base plate 101 is obtained by casting in the mould of Figure 1 when all partition walls 3 are removed from the mould, except for walls 28.

Figure 4 presents a situation in which the outer shell 102 of the fireplace body is laid on top of the base plate 101. It has been formed in the cast space 40 of the mould 1 into which partition walls 33 have been added. The walls 21' have been removed from the mould in order to obtain right angles to the outer shell. Also a core element 102 has been laid on the base plate, which core element has been formed in the cast space 41 of the mould 1 , from which cast space partition walls 23 have been removed before casting and to which partition walls 32 have been added. By means of the partition walls 32 and 33, an ash box opening 104 is formed to the layer.

Between the situations presented in Figures 4 and 5, three new layers have been laid to the fireplace body. In Figure 5, there is a core element 103 in the topmost layer which core element is formed in the combined cast space 41 and 41' of the mould 1 by removing the partition walls 23 before casting. The core element is lined by a shelf 105 which is formed in the mould 1 from which all other partition walls except the corners 28 have been removed outside the cast space 40 in order to form a skew corner 108.

Between the situations presented in Figures 5 and 6, two new layers have been laid to the fireplace body. In Figure 6, there is a core element 103 in the topmost layer which core element is formed in the cast space 41 of the mould 1. The core element is surrounded by the outer shell 102. It is formed in the cast space 40 of the mould 1 into which partition walls 22 have been added in order to form an opening 106 for the furnace. The walls 21 ' have been removed from the mould in order to obtain right angles 107 to the outer shell.

Between the situations presented in Figures 7 and 8, six new layers have been laid to the fireplace body. In Figure 8, the topmost layer contains an intermediate lid 109 in the middle of which there is an opening 110 for a so-called summer damper. The intermediate lid 109 is formed in the cast space 41 of the mould 1 by removing at first the inner walls 20, 20', 23 and 44. Only the rectangular partition wall 45, which has been defined for the opening 110 in the middle of the mould, has been left. The outer shell 102 surrounds the intermediate lid. It has been formed in the cast space 40 of the mould 1. The walls 21' have been removed from the mould in order to obtain right angles 107 to the outer shell.

Between the situations presented in Figures 8 and 9, five new layers have been laid to the fireplace body. In Figure 9, the topmost layer contains a cap 111 of the fireplace body. In the middle of it, there is an opening 112 for the flue. The cap 111 has been formed in the mould 1 from which all partition walls 3 have been removed except for the walls 28. The opening 112 in the middle of the cap has

been formed by placing a circular stencil having the size of the opening to the middle of the mould 1 before casting.

Only a few preferred embodiments of the invention are presented in the Figures. Facts of secondary importance regarding the main idea of the invention, facts known as such or apparent to a person skilled in the art, such as exact flue gas ducts inside the fireplace, are not separately shown in the figures. It is apparent to the man skilled in the art that the invention is not limited exclusively to the examples described above, but that it can vary within the scope of the claims presented below. The dependent claims present some possible embodiments of the invention, and they are not to be considered to restrict the scope of protection of the invention as such.