The object of the invention is a method for making a casing-like element construction from sheet metal and thermal insulation material fastened to it, inside which construction is formed a duct, for example, for air conditioning purposes. The object of the invention also comprises a casing-like element construction made from sheet metal and thermal insulation material fastened to it, inside which construction is formed a duct, for example, for air conditioning purposes.

Air-conditioning duct systems are usually made from sheet metal and mineral wool sheets, using different support laths and mouldings, and supporting with sheet metal folds. The metal sheets and mouldings are joined together by means of screws, rivets and spot welding. The duct systems are connected to each other by means of flange and slip joints. The duct systems are typically made of metal sheets and mineral wool mat, more or less by hand.

The disadvantages of this production method are, however, the slowness of the process and the considerable loss of the material used in production. Similarly, as a disadvantage of the finished product it can be mentioned that the product cannot be delivered ready surface-treated. Furthermore, the fire-technical dimensioning of the product is more limited and the tightness of the product cannot be sufficiently controlled.

The aim of the present invention is to achieve a new method for making an air-conditioning duct system of modular construction, and an air-conditioning duct which does not have the above-mentioned disadvantages.

It is characteristic of the method relating to the

invention that the element construction is assembled from composite panels made of sheet metal and thermal insulation material, the structure of the panels comprising a sheet metal-insulation-sheet metal layer, and that composite panels are fastened next to each other to form a casing¬ like element construction, by fastening together the metal sheets of two adjacent composite panels by means of the support and/or form elements anchored to them in order to produce a bearing construction, and that composite panels are joined in succession by means of tongue-and-groove joints which are formed by bending the edges of the metal sheets of the composite panels so far between those surfaces of the composite panels which come against each other that a tongue-and-groove joint can be formed of them.

It is also characteristic of the element construction relating to the invention that the element construction comprises composite panels made from sheet metal and thermal insulation material, the structure of the panels comprising a sheet metal-insulation-sheet metal layer, and that composite panels are fastened next to each other to form a casing-like element construction, by fastening together the metal sheets of two adjacent composite panels by means of the support and/or form elements anchored to them in order to produce a bearing construction, and that composite panels are connected in succession by means of tongue-and-groove joints which are formed by bending the edges of the metal sheets of the composite panels so far between those surfaces of the composite panels which come against each other that a tongue-and-groove joint is formed of them.

The method relating to the invention makes possible, for example, the production of the outer jacket of the appliances and chambers of air duct systems from industrially manufactured thermal insulation-sheet metal composite panels or other equivalent materials.

It is also characteristic of the use of the device relating to the invention that the element construction is used in ventilation installations or the like as the fire, thermal insulation and acoustic jacket of duct, appliance or chamber constructions.

The invention is described in the following with examples, with reference to the appended drawings in which

Figure 1 shows the element construction relating to the invention. Figure 2 shows the joining together of two adjacent composite panels of figure 1, and the structure of the duct system support of the form element. Figure 3 shows a tongue-and-groove joint between two successive composite panels. Figure 4 shows another embodiment of the tongue-and-groove joint of figure 3. Figure 5 shows the fastening of two successive composite panels of figure 3 to each other.

Figure 1 shows the casing-like element construction 10 relating to the invention made of sheet metal 11, 11' and of thermal insulation material 12 fastened to it. A duct 13 is formed inside the element construction 10, and the construction 10 being formed is suitable for use, for example, as the fire, thermal and acoustic insulation jacket of ventilation installations. Composite panel 20 is used as the material for making the element construction, the structure of the panel consisting of a glued sheet metal-mineral wool-sheet metal composite. From the composite panel 20 are made, by means of different cutting methods and by bending, duct system parts which are joined together. The composite panels 20 are fastened to each other by means of the support and/or form elements 40 anchored to the metal sheets 11 of two adjacent composite panels 20 in order to produce a bearing construction. The interior and exterior joint surfaces of the element

construction 10 are sealed at the seams and joints. The use of the elements 10 does not place restrictions of any kind on the shape of the duct system. From the element constructions 10 produced according to the new method are made fire-resistant and thermally insulated duct, appliance or chamber constructions.

The sheet metal surfaces 11, 11', already surface-treated with different colour alternatives, do not require separate surface treatment afterwards, and thus the product will have a finished appearance already at the production stage. The fastening of the composite panels 20 formed together is done quickly and cleanly, and the fastening can be done on both interior and exterior surfaces. The element constructions 10 assembled at the installation site are fastened, for example, by means of duct system supports 44 fitted in form elements 40 either to ceiling or wall structures, or they are separate bearing structures as parts of support pillars or the like. The lightweight, factory-made parts of the element constructions 10 can be transported in parts to the construction site, and larger units can also be made from the parts.

Figure 2 shows the joining together of two adjacent composite panels 20 of the element construction 10, and the structure of the form element, such as the duct system support 44 of the corner piece 40. The joint surfaces 35 of the composite panels 20 are cut at an angle of 45°. The exterior corner 46 of the element construction 10 is reinforced by an -shaped corner piece 40. Between the corner piece 40 and the outer surfaces of the preferably 1 mm thick metal sheets 11 is placed a seal 33 of the desired sealing class, made for example of cellular rubber, which is fixed in place for example by glueing to the interior surface of the corner piece. The corner piece 40 is fastened by means of screws 31 or rivets to the metal sheet 11 of the outer surface of the composite panel 20. Similarly, in the interior corner 47 of the element

construction 10 is placed an L-shaped support element 51, made for example of aluminium or rubber and fastened to the metal sheet 11' on the interior surface of the composite panel 20 by means of screws 31 or glue. The interior corner 47 can be sealed with a silicone-containing seal 33' if desired. By this method an extremely robust and airtight construction is achieved.

The duct system support 44 fitted to the form element is a part of the corner piece 40, which is fastened to the outer surface of the composite panel 20 of the element construction 10 by means of screws 31. The duct system support 44 is preferably a piece made from a steel form element 40 by bending. By means of the duct system support 44, the element construction 10 can be supported on the support structure by means of a threaded support rod 45.

Figure 3 shows a tongue-and-groove joint 21 between the composite panels 20 of two successive element constructions, by means of which joint the composite panels 20 can be fastened to each other. The edges 23, 24 and 23', 24' of the metal sheets 11, 11' of the composite panels 20 are bent so far between those surfaces of the composite panels 20 which come against each other that a tongue-and- groove joint 21 can be formed of them. The tongue-and- groove joint 21 is produced when the edges 23, 23' and 24, 24' of both the metal sheets 11, 11' on either side of the thermal insulation layer 12 are bent towards each other over some distance. The bent edge is formed into a sheet metal fold 28, 28' and 29, 29'. Between the sheet metal folds 28', 29' remains an insulation fold 27 forming a so- called butt seam, the length of the fold corresponding in the main to the thickness of the composite panel 20, and its thickness being 5 mm. When successive composite panels 20 are joined together, the edges 23 and 23', and 24 and 24' of the metal sheets match, and the metal folds 28 and 28', and 29 and 29' come against each other. When the insulation fold 27 meets the surface of the insulation

sheet remaining between the sheet metal folds 28 and 29, it presses tightly against the said surface. Sealings 60 are in addition placed between the tongue-and-groove joint 21 in the sheet metal fold 28', 29' to produce a fireproof and tight joint. With the solution relating to the invention, direct contact between the metal sheets 11 and 11' is prevented. Thus, in the element construction, the formation of cold bridges is prevented, as is the spread of fire through the tongue-and-groove joint 21 in case of a fire.

Figure 4 shows another embodiment 22 of the tongue-and- groove joint 21 of figure 3, by means of which the composite panels 20 of two successive element constructions can be fastened together. The edges 25, 25 ' and 26, 26' of the metal sheets 11, 11' of the composite panels 20 are' bent so far between those surfaces of the composite panels 20 which come against each other that a tongue-and-groove joint 22 can be formed of them. The tongue-and-groove joint 22 is produced when the edges 25, 25' and 26, 26' of both the metal sheets 11, 11' on either side of the thermal insulation layer 12 are bent towards each other over some distance. The bent edge is formed into a sheet metal fold 28, 28' and 29, 29'. Between the sheet metal folds 28', 29' remains an insulation fold 27 forming a so-called butt seam, the length of the fold corresponding in the main to the thickness of the composite panel 20, and its thickness being 5 mm. When successive composite panels 20 are joined together, the edges 25 and 25', and 26 and 26' of the metal sheets match and the sheet metal folds 28 and 28', and 29 and 29' come against each other. When the insulation fold 27 meets the surface of the insulation sheet remaining between the sheet metal folds 28 and 29, it presses tightly against the said surface. Sealings 60 are in addition placed between the tongue-and-groove joint 22 in the sheet metal fold 28', 29' to produce a fireproof and tight joint. With the solution relating to the invention, direct contact between the metal sheets 11 and 11' is prevented. Thus, in the element construction, the formation of cold bridges is

prevented, as is the spread of fire through the tongue-and- groove joint 22 in case of a fire. As sealing 60 between the tongue-and-groove joint 22 O-sealing can be used, for example. As O-sealing material for example, expanded rubber band, cellular rubber, or other equivalent material can be used. When, at the installation stage, the surfaces of the edges 25, 25' and 26, 26' are against each other, the fastening of the element constructions with respect to each other is always correct, and at the same time the correct deflection of the sealing 60 is achieved. By means of the jacket construction formed, the element constructions 10 can be classified into higher fire classes than could be done with the old construction methods.

Figure 5 shows how the composite panels 20 of two successive element constructions 10 are fastened together. The figure shows the tongue-and-groove joint 21 of figure 3. The parts of the element construction 10 can be joined by means of different tightening and fastening elements known as such. In the joint shown in the figure there are two L-shaped fastening elements 52, 52' for each screw fastening, which may be situated either inside or outside the element construction 10. The sample solution uses a fastening element 52, 52' fastened to the composite panel 20 by means of screws 31. As sealing materials 60, for example, expanded rubber band or cellular rubber can be used. Between the bottom surface of the fastening element 52, 52' coming against the sheet metal 11 and the sheet metal a sealing may also be placed if necessary. The fastening elements 52, 52' are joined to each other by means of clamp bolt joints 34. The sealing 60 placed ^■ between the edges of the tongue-and-groove joint 21 is compressed when the fastening elements 52 are tightened. As the surfaces of the the fastening elements coming against each other are locked together, the fastening of the duct system parts with respect to each other is always correct, and at the same time the correct deflection of the sealing 60 is achieved.

It is obvious to one skilled in the art that the different embodiments of the invention may vary within the scope of the claims presented below.