MANUFACTURE

TECHNICAL FIELD

The present invention relates to a connecting piece for a duct, preferably a ventilation duct, and comprising an inner flow space in communication with the interior of the duct, the connecting piece having at least one joining portion on which an end region of the duct is slidable and fixable.

The present invention also relates to a method of manufacturing a connecting piece intended for a duct, which is provided with an inner flow space and at least one joining portion for cooperation with the duct.

Finally, the present invention relates to a tool for manufacturing a connecting piece for a duct, and comprising a female union with a concave forming surface, the forming surface corresponding to the configuration of the outside of a shell body which forms part of the connecting piece, and a male union with a convex forming surface corresponding to the configuration of the inside of the shell body.

BACKGROUND ART PCT Application SE 2009/000281 discloses a ventilation duct which is produced from a compressed fibre material with a minor admixture of binder. The duct has longitudinal flexural lines in the corner regions, while the walls of the duct have transverse pivotal portions, rigidifying portions and relatively soft portions so that, in the unloaded or unstressed state, the duct displays a rectangular, possibly square cross section and is self-supporting across considerable lengths, up to between 2 and 3 m. Further, the duct is slightly flexible as a result of the presence of the relatively soft portions in the walls of the duct. In one variation of the above-described duct, the duct has, on two opposing sides, been provided with longitudinal fold lines so that the cross-sectional configuration of the duct may thereby be modified from rectangular to hexagonal configuration. As a result, two opposing sides will be approximately twice as wide as the remaining four sides. Further, the cross-sectional configuration may vary so that it will be more or less flattened.

For interconnecting and joining duct sections of the above-outlined types, different types of connecting pieces are required, which may be straight connecting pieces of varying lengths, T-junctions, bends with different angles of curvature and radii, etc.

Those connecting pieces that are previously known in the art have been intended for ventilation ducts manufactured from sheet metal material and consist of the same material themselves. This implies high manufacturing costs, often requirements on external insulation given the risk of condensation and needs for fire protection, and also probably considerable assembly- and sealing problems if they were to be used together with the above-described duct types.

PROBLEM STRUCTURE

The present invention has for its object to design the connecting piece intimated by way of introduction such that it may be manufactured at low cost, that it inherently possesses a superior insulation property, that there are no fire hazards, and that simple assembly may be put into effect.

The present invention also has for its object to design the method intimated by way of introduction such that the advantages inherent in the thus manufactured connecting piece will be attained. Finally, the present invention further has for its object to design the tool intimated by way of introduction such that it permits simple, rapid and economical manufacture, as well as adjustment of the tool for the manufacture of connecting pieces of different designs.

SOLUTION

The objects forming the basis of the present invention will be attained if the connecting piece intimated by way of introduction is characterised in that the connecting piece includes a compressed fibre material and a binder, that the connecting piece displays a substantially configurationally stable portion in association with the joining portion, and that the connecting piece displays, at least interiorly, a layer which is impervious to a fluid, in particular a gas, this layer being adjacent the inner flow space of the connecting piece.

Regarding the method, the objects forming the basis of the present invention will be attained if the method comprises the steps that two mirror- symmetric, possibly continuous shell bodies are produced by compression of a fibre material and a binder, that the shell bodies are provided with substantially configurationally stable portions in association with those portions that, in the finished state of the connecting piece, are to form the joining portion, that the shell bodies, at least on that side which, in the finished state of the connecting piece, is turned to face towards the flow space, is provided with a layer which is impervious to a fluid, in particular a gas, and that the shell bodies are united together.

Finally, the objects forming the basis of the present invention will be attained regarding the tool if the tool is characterised in that the forming surfaces are composed of edge surfaces on lamellae which are included in the female union and the male union.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detail hereinbelow, with particular reference to the accompanying Drawings. In the accompanying Drawings: Fig. 1 shows a first embodiment of a straight connecting piece according to the present invention;

Fig. 2 shows two shell bodies which together form the connecting piece

according to Fig. 1;

Fig. 3 shows a connecting piece formed as a T-junction;

Fig. 4 shows two shell bodies which together form the T-junction according to

Fig. 3;

Fig. 5 is a longitudinal section through a connecting piece according to Fig. 1 and a duct section mounted thereon; and Fig. 6 shows a tool for manufacturing a T-junction according to Figs. 3 and 4.

DESCRIPTION OF PREFERRED EMBODIMENT

The present invention will be described hereinbelow as being in the form of a connecting piece, but it will be obvious to the skilled reader that the technology described below is just as advantageously applicable in the manufacture of longer connecting pieces or duct sections.

As will be apparent from the Figure, the connecting piece according to Fig. 1 has an oval, possibly elliptic cross section, which more or less approximates the configuration of the duct described by way of introduction displaying hexagonal cross section. The cross-sectional configuration may be more or less elongate and narrow, and thus deviate from the illustrated configuration both in a rounder direction and in a flatter direction. Further, the oval cross section is advantageous given that the internal mounting dimensions for a connecting piece designed in this manner will be smaller than would otherwise be the case. Naturally, this by no means prevents a duct of the type described by way of introduction from having a rectangular cross section throughout large longitudinal sections while, on the other hand, the cross section is reconfigured to hexagonal configuration at those portions where the connecting pieces are to be mounted.

If the connecting piece is intended for cooperation with a ventilation duct which only displays rectangular, possibly square cross section, the cross section of the connecting piece may instead be rounded, possibly circular.

The connecting piece according to Fig. 1 is manufactured from a fibre material, for example glass fibre or mineral wool, which has a minor admixture of a binder which may be activated by heating. Hereby, the connecting piece will, depending on the degree of compression of the fibre material, be able to be given different properties in different parts. Thus, the connecting piece according to Fig. 1 has a central portion, which is a substantially configurationally stable portion 1 and which contains a considerably greater quantity of fibres per surface unit than is the case for the remaining portions of the connecting piece. On either side of the substantially configurationally stable portion 1, the connecting piece has at least one but preferably two joining portions 2 which are intended for joining of end portions of a duct 5 (see Fig. 5) of both of the types that were described by way of introduction. For sealing against such a duct 5, the joining portions display circumferential recesses 3 (seen particularly clearly in Fig. 5), these recesses 3 being intended for accommodating suitable sealing rings or gaskets.

Finally, the connecting piece displays, adjacent the joining portions 2, entry portions 4 which may be deformed under quite slight loads and which display considerably lesser material thickness than both the joining portions 2 and the configurationally stable portion 1. The material thickness of the entry portions may lie in the order of magnitude of between 1 and 2mm, while the material thickness in the joining portions 2, apart from the recesses 3, may lie in the order of magnitude of between 3 and 6mm, while finally the material thickness of the substantially configurationally stable portion 1 may lie in the order of magnitude of between 10 and 15mm. For reasons of fire safety, it is important that the quantity of combustible binder is kept as low as possible. Nevertheless, it may be conceivable to employ different

concentrations of binder in the entry portions 4, the joining portions and in the substantially configurationally stable portion 1. In particular, the concentration may be increased in the substantially configurationally stable portion 1 and possibly also in the joining portions 2.

According to the present invention, the degree of compression is considerably higher in the substantially configurationally stable portion 1 than is the case in both the joining portions 2 and the entry portions 4, which is achieved in that considerably more fibres are compressed in the substantially configurationally stable portion than in the remaining portions of the connecting piece. Thus, that layer of uncompressed fibres which is to form the substantially configurationally stable portion 1 may amount to 10- 20cm, while considerably thinner layers are employed for the joining portions 2 and the entry portions 4. As a norm for the compression pressure, mention might be made of approx. 10kp/cm ² .

It will be apparent from Figs. 2 and 5 that the connecting piece has an inner flow space which is in flow communication with that duct section 5 which is intimated to the right in Fig. 5. This flow space has been given reference numeral 6 in the Figures. It will be apparent from the Figures that the flow space 6 has a smooth contour over those parts of the connecting piece which consist of the substantially configurationally stable portion 1 and the two joining portions 2. Those differences in material thickness which exist between these portions are thus realised on the outside of the connecting piece. Such a smooth contour is advantageous in terms of simple cleaning of the interior of the connecting piece.

On the other hand, the transition between the entry portions 4 and the two joining portions 2 takes place on the inside of the connecting piece so that there is formed therebetween an obliquely inclined transitional surface 7. It will further be apparent from the Drawing that the outside of the entry portions 4 lies flush with the outside of the two joining portions 2 so that the duct 5 will thereby have a smooth outside to abut against, apart from those grooves or recesses 3 which are intended for sealings.

It will be apparent from Fig. 5 that, exteriorly on the duct section 5, there is disposed a clamp 8 which, in the axial direction of the connecting piece, is of a width which approximately corresponds to the width of the joining portion 2. Further, the clamp 8 displays inward bulges in register with the recesses 3, these bulges being intended to clamp with particular force on the areas of the duct section located there, into sealing abutment against the sealing rings or gaskets disposed in the recesses 3. The clamp 8 may be manufactured from sheet metal and be open so that it is drawn together under the action of a suitable clamping means, such as a bundle tie 9 or the like.

In Fig. 2, which shows two shell bodies 16 which together form the connecting piece according to Fig. 1, it is clearly apparent how the shell bodies are produced from fibre material. The shell bodies 16 are identical or mirror- symmetric, and are manufactured in the same tool, for which reason just a simple joining together of the two shell bodies needs to take place before a complete connecting piece is realised.

On mounting of a duct 5 on a connecting piece, use is made of a shoehorn-like took, by means of which the entry portion 4 is deformed so that it may readily be passed into the duct 5. Even if the duct 5 is of limited deformability, it should in this context be considered as inflexible in the circumferential direction.

According to the present invention, the connecting piece according to the present invention displays, at least on its inside, a layer which is impervious to a fluid, in particular a gas, and which may, for example, consist of a foil of suitable plastics material. Preferably, the outside of the connecting piece, at least on the joining portions 2 and the entry portions 4, has a corresponding layer that is impervious to a gas. This layer may be formed as an adhesive sealing layer which bonds to the outside of the duct 5. In such an embodiment, no grooves or recesses 3 and no separate sealing rings or gaskets are necessary. The reverse procedure is also possible, i.e. to place the adhesive sealing layer interiorly in the duct 5. If will further be apparent from the Drawings that the connecting piece, in the substantially configurationally stable portion 1, may be provided with a depression 10, with a locally reduced material thickness, for cooperation with a suspension clip or the like.

Figs. 3 and 4 show a connecting piece formed as a T-junction, as well as both of the shell bodies 16 from which such a connecting piece is formed. This T-junction also displays, in its central region, a substantially configurationally stable portion 1 of considerably greater material thickness than is the case for the remainder of the T- junction. A branch connection 11 is, in the illustrated embodiment, connected at right angles to the connecting piece, but may naturally display another connection angle. It will further be apparent that the branch connection 11 has an entry portion 4 and a joining portion 2. It will also be apparent that the branch connection 11 also has a substantially configurationally stable portion which is preferably of one piece manufacture with the substantially configurationally stable portion on the main part of the connecting piece.

Finally, it will be apparent from Figs. 3 and 4 that the branch connection 11 is of smaller dimensions than is the case for the connecting piece at large. Thus, the branch connection 11 is dimensioned for a smaller duct than is the case for the rest of the connecting piece proper.

Figs. 1 to 4 show two different embodiments of a connecting piece according to the present invention. However, the present invention encompasses connecting pieces of different designs, which may be formed as bends, both vertical and horizontal, with different radii of curvature and different angles of curvature. Further, the connecting piece may be in the form of a cross connection, thus an embodiment similar to the embodiment according to Figs. 3 and 4 where an additional branch connection is provided. The connecting piece may display a change in surface area.

On manufacture of a connecting piece according to the present invention, two shell bodies 16 are first manufactured, which may be contiguous together along a fold line, so that a finished connecting piece may be realised by folding together of the shell bodies splayed out on manufacture. Alternatively, the shell bodies may be completely separate and be joined together in a subsequent process. In order for this to be possible, the shell bodies are identical or mirror- symmetric.

As was intimated above, manufacture takes place by a pressing process where layers of fibre material of different thicknesses are compressed together in a tool to the intended final form of the shell body 16. Preferably, the fibre material is pre-heated in a preheating oven so that any possible moisture disappears before the actual pressing operation takes place in the press tool where the temperature is raised sufficiently for activation of the binder which is admixed in the fibre material.

Manufacture of the connecting piece may also take place in that layers of fibre material of different thicknesses are wound on or wrapped around a core which may consist of a plurality of part cores, whereafter the fibre material is compressed from the outside by a number of press jaws simultaneously as heat is supplied.

Fig. 6 shows one example of a tool designed for manufacture of a connecting piece according to the present invention, formed as a T-junction. The tool comprises a female union 12 and a male union 13 which both have forming surfaces 14 and 15,

respectively, and it is these forming surfaces that will impart the form to the shell body 16 produced in the tool. On manufacture of the shell body 16 according to Fig. 6, the binder- admixed fibre material is preferably placed in the female union 12 of the tool, with considerably more fibres in that part of the tool which is to form the substantially configurationally stable portion 1 of the connecting piece. Correspondingly, a lesser quantity of fibres is placed in that part which is to form the joining portions 2 of the connecting piece and yet again a lesser quantity of fibres is placed in that part of the tool which is to form the entry portions 4 of the connecting piece. Thereafter, the tool is closed in a pressing movement, at the same time as the tool is kept hot with the aid of the heating device 17 so that the temperature of the tool may be kept at a level which is sufficient for activation of the binder admixed in the fibre material. It will be apparent from Fig. 6 that the tool, both the female union 12 and the male union 13, is produced from a number of slats or lamellae 18 laid side-by-side in a package. These lamellae are held together by means of tie rods 19 or other suitable types of clamping devices.

As a result of the design of the female union 12 and the male union 13 as packages of lamellae, it will be the edge surfaces of the lamellae which will make up the forming surfaces 14 and 15 in the tool. The design of the tool as a package of slats or lamellae also entails that certain lamellae may readily be replaced, and thereby the shape of the tool be changed so that the greater part of the tool may be employed for manufacture of several different designs of the connecting piece.

Given that the tool includes a large number of lamellae 18, it is possible to dispose, between at least certain of them, channels for removing gases or for the supply of hot air on activation of the binder.

The present invention should not be considered as restricted to that described above and shown on the Drawings, many modifications being conceivable without departing from the scope of the appended Claims.