PROCESS AND APPARATUS FOR THE PREPARATION OF A TUBULAR SHEATHING OF MINERAL FIBRES FOR INSULATION PURPOSES

Abstract: Process and apparatus for the preparation of a tubular sheathing of mineral fibres for insulation purposes wherein a mineral fibre web is treated in at least one longitudinally extending zone in such a way that the bond between the fibres in this zone is weakened, the web thus treated subsequently being wound up so as to form a roll having an axially extending hole, and the roll being slit along a generatrix so as to provide an openable, easily bendable tubular sheating.

Description: Process and apparatus for the preparation of a tubular sheathing of mineral fibres for insulation purposes. The present invention relates to a process for the preparation of a tubular sheathing of mineral fibres, such as glass, rock and slag fibres, for insulation purposes wherein a mineral fibre web is wound up so as to form a roll having an axially extending hole, the roll being slitted along a generatrix so as to provide an openable tubular sheathing. The tubular sheathings prepared by such known process are rather rigid and may consequently not readily be used for insulating bent pipe sections. Consequently, it is known to cut off parts of the tubular sheathings in order thereby to make it possible to bend the tubular sheathings sufficiently for them to be fitted on pipe bends. Hereby the insulation capacity of the tubular sheathings is reduced, and extra work is required in order to insulate pipe systems with bends. It is the object of the invention to provide a tubular sheathing which is prepared in conventional way and possesses such flexibility that is can be used easily and without extra work, for insulating pipe bends. According to the invention this object is achieved by a process of the kind stated in the preamble, which is characterized in that the mineral fibre web, prior to the winding up as a roll, is treated in at least one longitudinally extending zone in such a way that the bond between the fibres in this zone is weakened. By the above treatment of the web prior to the winding up as a roll, areas are established in the finished roll which, as a consequence of the weakening zones being superimposed, impart a desired flexibility to the roll. The weakening mentioned of the bond between the fibres is obtainable in various ways. For example, a compression of the fibres may be performed in the longitudinally extending zone or zones. This may e.g. be achieved by exerting, during the advancing of the mineral fibre web, a linear pressure thereon in the said zone. By use of this embodiment, preferably a number of parallel, separated, weakening zones are established, e.g. by use of an embossing roller constituted by a number of axially separated discs. Alternatively, weakening is obtainable by removal of material by milling or cutting off. In such cases in which the bond between the fibres in the mineral fibre web has been provided by means of an organic binder contained in the web, the weakening of the bond is obtainable by heating the binder to decomposition temperature, e.g. by means of gas burners or hot rods. The process according to the invention is particularly well-suited for use in the preparation of tubular sheathings from mineral fibre webs having a density of 40-150 kg/m * * for mineral fibre webs of rock fibres, and of 40-100 kg/m ** for webs of glass fibres. The mineral fibre web may be prepared from rock fibres, glass fibres, slag fibres or other synthetic, inorganic fibres. The invention further relates to an apparatus for the preparation of tubular sheathings of mineral fibres for insulation purposes, which apparatus comprises means for winding up a mineral fibre web so as to form a roll having an axially extending hole, and means for slitting the roll so as to provide an openable tubular sheathing, the apparatus being characterized by further comprising means for weakening the bond between the fibres in the mineral fibre web in one or more longitudinally extending zones. The said means e.g. consist of pressure wheels which are capable of crushing the fibres in the zones mentioned, or of gas burners or hot rods. In the following the invention is described in more detail, reference being made to the drawing in which Fig. 1 schematically shows an apparatus for carrying out the process according to the invention, Fig. 2 shows a perspective view of the embossing and winding means in the apparatus according to Fig. 1, and Fig. 3 shows a longitudinal section of a pipe bend insulated with a tubular sheathing prepared by a process according to the invention. The apparatus shown in Fig. 1 comprises an endless conveyor belt which is supported by two or more rolls, only one of which, 2, is shown. A mineral fibre web 3 is advanced by the endless conveyor belt 1 which passes the web 3 through a roller pair comprising a lower supporting roller 4 and an upper embossing roller 5. As appears from Fig. 2, the embossing roller 5 comprises a number of mutually separated discs 6 mounted on a common shaft 7. During the passage though the roller pair 4, 5, a number of parallel line-shaped embossed zones 8, corresponding to the number of discs 6 on the embossing roller 5, are formed in the web 1. The embossing of the mineral fibre web 3 results in a significant weakening of the web in the zones 8 mentioned in that the fibres are partly crushed during the embossing. Having left the conveyor belt 1, the embossed mineral fibre web 3 is introduced between two rollers 10 and 11, which together with five other rollers 12, 13, 14, 15 and 16, one of which, e.g. 15, is connected with driving means not shown, support an endless elastic belt 17 which by¬ passes a pipe 18 being connected with driving means not shown and serving for winding up the mineral fibre web 3 as a roll. Due to the elasticity of the belt 17 it will, during the winding up of the mineral fibre web 3, become longer and thus permits formation of a roll 19 having gradually increasing outer diameter. Alternatively, use can be made of a non-elastic belt and one or more rollers 12-16 mounted on radially offsettable shafts. When the roll 19 has reached the desired wall thickness, the winding up is stopped, and the roll obtained is removed from the pipe 18, which is then ready for winding up a new roll. The roll 19 removed from the pipe 18 will upon slitting along a generatrix provide an openable tubular sheathing. As a consequence of axially separated weakening zones 8 having been established in the tubular sheathing, the weakened part of the tubular sheathing will be rather easily bendable, and is consequently well-suited for insulating a pipe bend 20 as illustrated in Fig.3. A tubular sheathing 21 prepared as described above is here fitted on a bent pipe 21. When mounting the tubular sheathing 21 on the pipe bend 20, such parts of the tubular sheathing which are to constitute the inner side of the pipe bend will be easily compressible, whereas the parts situated on the opposite side remain by and large intact. Consequently, the tubular sheathing will be easily conformable to the shape of the pipe bend 20.

Claims: C l a i m s : 1. A process for preparing a tubular sheathing of mineral fibres for insulation purposes wherein a mineral fibre web is wound up so as to form a roll having an axially extending hole, and where the roll is slitted along a generatrix so as to provide an openable tubular sheathing, c h a r a c t e r i z e d in that the mineral fibre web, prior to the winding up as a roll, is treated in at least one longitudinally extending zone in such a way that the bond between the fibres in this zone is weakened. 2. A process according to claim 1, c h a r a c t e r i z e d in that the weakening is accomplished by compressing the mineral fibres in the zone. 3. A process according to claim 2, c h a r a c t e r i z e d in that the crushing of the fibres in the weakening zone is accomplished by exerting, during the advancing of the mineral fibre web, a linear pressure thereon in the said zone. 4. A process according to claim 1, and where the mineral fibres in the mineral fibre web are bonded by means of a binder, c h a r a c t e r i - z e d in that the weakening is accomplished by heating the binder to its decomposition temperature in the said zone. 5. A process according to claim 4, c h a r a c t e r i z e d in that the mineral fibre web, during the advancing thereof, is exposed to the action of one or more burning gas jets. 6. An apparatus for preparing tubular sheathings of mineral fibres for insulation purposes, said apparatus comprising means for winding up a mineral fibre web so as to form a roll having an axially extending hole, and means for slitting the roll along a generatrix so as to provide an openable tubular sheathing, c h a r a c t e r i z e d in that it also comprises means for weakening the bond between the fibres in the mineral fibre web in one or more longitudinally extending zones.

Inventors: CRIDLAND IAN, HUSBJERG JENS, CRIDLAND, IAN, HUSBJERG, JENS
Applicants: CRIDLAND IAN, HUSBJERG JENS, ROCKWOOL INT, CRIDLAND, IAN, HUSBJERG, JENS, ROCKWOOL INTERNATIONAL A/S
Application year: 1996
Main classification: F16L59
IPC codes: F16L59