FIELD OF INVENTION The invention relates to a method defined in the preamble of claim 1. The invention also relates to an arrangement defined in the preamble of claim 11.

BACKGROUND OF INVENTION In the prior art, there are known methods and arrangements for manufacturing and assembling large- size filament-reinforced plastic composite hollow bodies, such as tanks and the like. The term ^λ large- size hollow body' here refers to elongate cylindrical objects having a diameter of the order of several meters.

The most advantageous and economical way to manufacture a hollow body casing is filament winding. In filament winding, the hollow body casing is manufactured in a filament winding device, where around a rotatable mold, i.e. mandrel, there is wound filament dipped in thermoplastic by feeding it from a filament dispenser that moves on the side of the mandrel, in the axial direction thereof, so that the filament is set in a spiraling fashion on top of the mandrel. By this technigue, the hollow body casing is made essentially cylindrical in shape, and the diameter of the casing corresponds to the diameter of the finished hollow body. Filament winding has several known advantages. It is easily automatized, and the pretensioning of filaments can be controlled accurately. Moreover, the orientation of the filaments can be accurately adjusted, so that the threads in superimposed layers can be either superimposed or pointed in different directions. In practice, there have been two alternatives for implementing large-size hollow bodies manufactured by filament winding.

A first alternative is to manufacture a hollow body on the manufacturing site, which is located far from the assembly site (for example in another locality, another country or another continent) , and transport it full-sized by land, railroad and/or sea from the manufacturing site to the assembly site, which is very expensive and in practice impossible. Transport expenses in ships are charged according to the volume, which makes the transport expenses per unit of mass very expensive for large, light-weight hollow bodies. In most countries, the limit for the diameter of an object to be transported by road or rail is roughly 3.5 m.

Further, US 3956816 A provides a method for producing a storage tank from a resilient material, such as a fiber glass reinforced plastic, in which a member is formed to a cylindrical configuration at a first location, flattened to an oblate configuration and held in said oblate configuration while transported to a second location, and then released so as to resume its cylindrical configuration, whereupon by addition of a base and a top the tank is completed. The member may be formed in sections at the first location with the sections being flattened to varying degrees so as to fit one within the other during transportation. Similarly, the top and base may be cut into sections and nested with the sections of the flattened member during transportation.

Another alternative with deliveries is solving said problem of transportation by building on the assembly site a temporary filament winding plant, in which case the hollow body is manufactured to the full size on the assembly site, for example as is described in the publication US 3,470,656. The problem with this method is that the transportation of the production equipment and its erection on the assembly site, as well as its dismounting and removal is expensive and troublesome. In addition, the conditions required in filament winding, such as ambient temperature and humidity, must be controlled precisely for ensuring the quality of the end product. This can be very difficult or even impossible, owing to local weather conditions, and the quality cannot be guaranteed. In practice, the project of establishing a filament winding plant on the assembly site is problematic also because local, professionally skilled persons must be found for erecting and using the equipment. This has also made it difficult to define the prices in supply offers, because when the offers have been drafted, it has been difficult or impossible to find out the expenses of the local project established on the assembly site.

OBJECT OF INVENTION

An object of the invention is to eliminate the above mentioned drawbacks.

A particular object of the invention is to introduce a method and arrangement that make it possible to essentially reduce freight expenses and minimize pricing risks with deliveries.

Another object of the invention is to introduce a method and arrangement that enable the manufacturing of a hollow body casing of a controlled quality in controlled conditions on a permanent manufacturing site, and its transportation to the assembly site by road, rail or sea as a regular, standard-sized freight object.

Yet another object of the invention is' to introduce a method and arrangement ensuring that highly skilled labor is not needed on the assembly- site .

SUMMARY OF INVENTION The method according to the invention is characterized by what is set forth in claim 1.

Moreover, the arrangement according to the invention is characterized by what is set forth in claim 11.

According to the invention, in the method an endless casing manufactured by filament winding is cut open in the axial direction, so that two ends are formed in the casing. The casing that is cut open is rolled up for forming a transport package that has an essentially smaller diameter than the finished hollow body. The transport package is transported to the assembly site. On the assembly site, the transport package is set in an assembly stand, the outer dimensions whereof are arranged to correspond to the inside diameter of the finished hollow body. The casing is unrolled around the assembly stand, to the size of the finished hollow body, so that the casing ends are matched end-on-end. The casing ends are mutually fastened by a tight-fitting seam for forming an endless casing. Finally other required elements are attached to the casing for obtaining a finished hollow body.

According to the invention, the arrangement includes a cutting device for cutting the endless casing, manufactured by filament winding, open in the axial direction. Moreover, the arrangement includes a rolling device for rolling up the casing to form a transport package with a diameter that is essentially smaller than the diameter of the finished hollow body. In addition, the arrangement includes an assembly stand, the outside diameter of which corresponds to the inside diameter of the finished hollow body, and which is arranged to receive inside it the transport package in order to unroll the casing on top of the assembly stand.

An advantage of the invention is that owing to the transport package, where the casing is for transportation rolled up in a size that is essentially smaller than a full-sized hollow body, the transport expenses remain essentially lower than the transport expenses of a hollow body that is transported in full size, because the hollow body casing can be transported to the assembly site by road, rail or sea as a regular, standard-sized freight object. Moreover, it is an advantage that the delivery expenses are easily predicted, and offers can be priced without risks. Another advantage is that it is not necessary to transport and build a temporary filament winding equipment on the assembly site. The casing can be produced on a permanent manufacturing site, where conditions can be controlled, and thus also the quality of the end product can be guaranteed. Highly skilled labor is not needed on the assembly site.

In an embodiment of the method, the casing is manufactured by filament winding to a thickness that is selected according to the minimum bending radius required by the transport package diameter.

In an embodiment of the method, the casing is manufactured by filament winding to a thickness that is roughly 4 - 8 mm, preferably roughly 6 mm.

In an embodiment of the method, the open-cut casing is rolled up on a capstan body, to form a transport package with a diameter that is essentially smaller than the diameter of the finished hollow body.

The capstan body makes it easier to handle the transport package in production, storage, transportation and assembly. In an embodiment of the method, after the casing is on the assembly site formed to be endless in shape, on the outer track of the casing, there are fastened reinforcement elements, such as stiffening rings, stiffening ribs and the like, for improving the structural strength and rigidity of the casing. When the casing is by filament winding manufactured to a thickness that is selected according to the minimum bending radius required by the transport package diameter, said thickness is usually smaller than the one that would be needed with respect to the strength required in the finished hollow body. The missing thickness can be compensated by said reinforcement elements to be installed on the assembly site. In an embodiment of the method, the measures of the transport package are adjusted to match a standard ISO freight container. Owing to the standardized measures, the transport expenses can be accurately predicted and calculated. In an embodiment of the method, the transport package is transported to the assembly site in an ISO freight container. For example in a regular ISO freight container, with the following measures: length 40 feet, width 8 feet, and height 8.5 feet, there can be transported, as a transport package, the casing of a tank that is 10 meters high and has a diameter of 6 meters .

In an embodiment of the method, the transport package is on the assembly site set in a vertical position in a vertical assembly stand.

In an embodiment of the method, the capstan body is rotated around its axis for unrolling the casing around the assembly stand.

In an embodiment of the method, the casing ends are mutually fastened by laminating reinforced plastic mat in order to form a seam. In an embodiment of the arrangement, the arrangement includes a capstan body, around which the open-cut casing can be rolled up as a transport package. The assembly stand is arranged to receive inside it the capstan body for unrolling the casing on top of the assembly stand.

In an embodiment of the arrangement, the assembly stand includes an actuator, which is arranged to rotate the capstan body. In an embodiment of the arrangement, the assembly stand comprises a rigid frame, including a number of columns, which are mutually arranged in a circular configuration and radially with respect to the vertical central axis of the assembly stand. Moreover, the frame includes at least two spaced-apart horizontal support rings, on the inner track whereof the columns are attached, the outside diameter of the structure formed by said support rings corresponding to the inside diameter of the finished tank, and both rings being provided with an opening. A number of horizontal supports is arranged to fasten the mutually facing and adjacent columns to each other. In between the horizontal supports and inside the space defined by the support rings, there is formed a reception space for receiving the transport package inside the assembly stand, so that the outer track of the transport package touches the outer track of the rings at the openings, in which case the casing can be fed through said openings from the transport package to cover the assembly stand.

In an embodiment of the arrangement, the capstan body is provided with a shaft. A circular end flange is fastened to the shaft, and the diameter of the end flange is at least as large as the diameter of the casing wound on the capstan body. The core, around which the casing can be wound, is attached to the shaft . In an embodiment of the arrangement, the actuator is arranged to be connected to the shaft for rotating the capstan body.

LIST OF DRAWINGS

The invention is explained in more detail below, with reference to exemplifying embodiments and to the appended drawing, where

Figure 1 illustrates how the casing of a hollow body is manufactured according to an embodiment of the invention by filament winding on the manufacturing site,

Figure 2 illustrates the cutting of a casing by a cutting device in the lengthwise direction, Figure 3 illustrates the device of Figure 2, viewed in the direction III-III of Figure 2,

Figure 4 illustrates an open-cut casing as set in a winding device for winding it on the capstan body,

Figure 5 illustrates the section along the line V-V in Figure 4,

Figure 6 illustrates a casing that is wound by the winding device as a transport package on the capstan body,

Figure 7 illustrates a section along the line VII-VII of Figure 6,

Figure 8 is an axonometrical illustration of the transport package of a hollow body casing, belonging to an embodiment of an arrangement according to the invention, to be used in an embodiment of the method of the invention,

Figure 9 is an axonometrical illustration of an assembly stand, belonging to an embodiment of an arrangement according to the invention, to be used in an embodiment of the method of the invention, Figures 10 - 14 illustrate the various steps in an embodiment of the method according to the invention for mounting the casing on the assembly site, and

Figure 15 illustrates a finished hollow body, which in this exemplary case is a cooling tower.

DETAILED DESCRIPTION OF INVENTION

Figure 1 is a schematical illustration of a regular filament winding device 9 used for manufacturing large-size cylindrical filament reinforced plastic composite hollow bodies, such as tank shells, reactors, towers, pipes, chimneys, columns etc. casing shells used in the chemical and metallurgical industry. The device includes a rotatable mandrel 10, the outside diameter of which corresponds to the inside diameter of a finished hollow body. The device is provided with a movable filament dispenser 11, which feeds filament dipped in thermoplastic on the rotary mandrel 10 in a desired shape and as a suitable number of layers, in a desired thickness. The thermoplastic can be for example epoxy resin, polyester resin, vinyl ester resin or phenolic resin. The filament can be glass or carbon filament, and in structure, it can be cut filament, roving yarn, woven texture or mat. The thickness, in which the casing 1 is wound, is selected according to the minimum bending radius required by the diameter of the transport package 4 (cf. also Figures 5 - 8), so that the casing could be easily and undamaged bent on the capstan body 6. For instance when manufacturing a cylinder casing 1, with a diameter D being 6 meters, there is selected a thickness of roughly 4 - 8 mm, preferably 6 mm. Thus the casing 1 can be rolled as a transport package 4 illustrated in Figures 5 - 8, which fits in a 2.6 m wide ISO freight container. However, because said thickness 6 mm is possibly not sufficient in the final, assembled hollow body, with respect to structural rigidity and strength, there may be needed additional reinforcement elements 7, 8 (Figure 13), to be installed on the assembly site. When a desired thickness is reached for the casing 1, the mandrel 10 with the casing 1 is in the regular way put in a furnace (not illustrated) for curing the resin. When the resin is set, the mandrel 10 is removed. Then the hollow cylindrical casing 1 is shifted to the ^' cutting device 12, illustrated in Figures 2 and 3, for cutting the casing 1 open in the axial direction, so that two ends 2, 3 are formed in the casing.

Figure 4 is a schematical illustration of a rolling device 13, by which the open-cut casing 1 can be rolled up around the capstan body 6 for forming a transport package 4 (Figures 4 - 6), said transport package 4 having a diameter d that is essentially smaller than the diameter D of the finished hollow body (cf . Figure 7) . As can be seen for example from Figures 5 and 8, the capstan body 6 includes a shaft 20. A circular end flange 21 is attached to the shaft 20. The diameter of the end flange 21 is at least as large as the diameter d of the casing 1 wound on the capstan body 6. To the shaft 20, there is fastened a core 22, around which the casing 1 is wound.

Figure 8 shows a finished transport package 4, which is supported in a horizontal position by support elements. The measures of the transport package 4 are adjusted to match a standard-sized ISO freight container. Then it can be transported to the assembly site in an ISO freight container.

Figure 9 illustrates an assembly stand 5, which is used as mounting jig for the hollow body on the assembly site. The outside diameter of the assembly stand 5 corresponds to inside diameter of the finished hollow body. The assembly stand 5 is arranged to receive inside it the transport package 4 for unrolling the casing 1 on the assembly stand 5.

From Figure 9 it is seen that the assembly stand 5 includes a rigid frame. The frame comprises four vertical columns 15, which are arranged in. a circular configuration with respect to each other and radially with respect to the vertical central axis of the assembly stand 5. Two horizontal support rings 16 are attached at the bottom and top ends of the columns. The columns 15 are attached on the inner track of the support rings 16. The outside diameter of the support rings 16 corresponds to the inside diameter of the finished tank. At the support rings 16, there are arranged horizontal supports 18 that attach the mutually facing and adjacent columns 15 to each other. In between the horizontal supports 18 and inside the space defined by the support rings 16, there is formed a reception space 19, in which the transport package 4 can be set inside the assembly stand 5 according to Figures 10 and 11, so that the outside track of the transport package 4 touches the outside track of the support rings 16 at the openings 17 provided in the support rings 16, and thus the casing 1 can, through the openings 17, be fed from the transport package 4 onto the assembly stand 5, as is illustrated in Figure 11. The assembly stand 5 can also include an actuator 14 illustrated schematically in Figure 11, which actuator 14 is arranged to be connected at the end of the shaft 20 for rotating the capstan body 6, so that the casing 1 can be brought around the assembly stand 5.

In Figure 12, the ends 2, 3 of the casing 1 are matched end-on-end, so that the ends 2, 3 can be laminated together by a tight-fitting seam for forming an endless casing 1.

Figure 13 illustrates a step where on the outer track of a casing 1 formed in a cylindrical endless shape, there are attached reinforcement elements 7, 8, such as stiffening rings 7, lengthwise stiffening ribs 8 or the like, for improving the structural strength and rigidity of the casing. In Figure 14, the assembly stand 5 is removed from the hollow body.

Finally other required elements are attached to the casing 1.

Figure 15 illustrates a finished hollow body, which in this example is a cooling tower, the technique of which is explained in more detail in the publication WO2007/096457 A2 by the same applicant.

The invention is not restricted to the above described embodiments only, but many modifications are possible within the scope of the inventive idea defined in the claims.