ES2564492T3 - Insulation system for a Yankee cylinder - Google Patents

Abstract

An insulation for the end heads (13, 15) of a Yankee cylinder (2), comprising: - a plurality of insulation panels (51); - a clamping ring (81), divided into at least two portions (81A) and attachable with a support and rotation structure (3), such that said clamping ring has clamping members (88) to confine each one of said insulation panels in a radially inner first position; - for each insulation panel (51), at least one intermediate clamping element (91), configured to be confined to at least one head of a screw (111) provided in the end head (13; 15) of the Yankee cylinder (2), at a certain radial distance from said support and rotation structure (3), such that said intermediate clamping element (91) defines at least one clamping point for the respective insulation panel (51).

Description

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DESCRIPTION

Insulation system for a Yankee cylinder Technical field

The present invention relates to improvements in the so-called Yankee cylinders that are used for the manufacture of paper.

State of the art

In accordance with the most traditional techniques, the paper is manufactured from an aqueous sludge of cellulose fibers and possible additional additives, with a very low dry content, of the order of fractions of percentage point by weight.

The sludge is supplied from a bedside box, on a Fourdrinier wire, and, through subsequent stages between wires and felts, with the use of suction systems, the amount of mud water is gradually reduced until a veil or cellulose fiber layer with a water content low enough to have a consistency that allows the veil to be passed through a drying system. In some papermaking machines, the drying system comprises a Yankee cylinder, that is, a hollow cylinder inside which a heat transfer fluid, usually steam, is circulated. The paper web is dried, that is, its water content is reduced, by evaporation at the expense of heat transferred from the Yankee cylinder through its outer wall, along which the veil of paper material is driven.

Examples of Yankee cylinders are disclosed in US-A-3,224,084, US-A-3,116,985, US-A-3,911,595, US-A-3,914,875, US-A-4,320,582 and GB -685.009.

Traditionally, Yankee cylinders were made of cast iron. More recently, Yankee cylinders made of steel have been proposed, as disclosed, for example, in WO-A-2006/057023 and WO-A-2008/105005.

Yankee cylinders made of steel are normally made by welding and comprise an outer cylindrical surface consisting of a cylindrical half-turn whose ends are fixed to the end heads. The union is usually done by welding. The end heads externally carry the cylinder support pins. The hollow interior volume of the Yankee cylinder into which the steam is introduced for heating the outer surface of the Yankee cylinder is defined between the end heads and the half-turn.

The end heads of Yankee cylinders made of steel are generally flat, contrary to the end heads of Yankee cylinders made of cast iron, which have a curved shape with a concavity facing outward. An example of a Yankee cylinder made of steel is disclosed in document W0-A-2008/105005.

The steam injected into the Yankee cylinder has to transfer heat to the paper web through the cylindrical surface. The residual heat that passes through the surface of the heads constitutes a loss of energy. US-A-4,520,578 discloses a Yankee cylinder with concave end heads made of cast iron and provided with an insulation system whose function is to reduce the amount of heat wasted through the end heads. Other insulations of Yankee cylinders and / or other drying cylinders are disclosed in WO-A-82/03909, US-A-4,321,759, US-A-4,454,660, US-A-4,399,169, US -A-4,506,459, US-A- 4,372,055, US-A-4,241,518 and US-A-4,313,267. All these insulation systems are peripherally anchored around the head, and make use, as anchor points, of the screw heads that connect the head to the half-turn of the cylinder. These insulation systems, therefore, are not suitable for insulating the end heads of a welded Yankee cylinder made of steel.

WO-A-2011/030363 discloses a system for insulating a Yankee steel cylinder. This system has been designed in particular for application in cylinders devoid of screws that connect the end heads of the cylinder to the half-turn. This makes it possible to weld a perimeter ring along the outer edge of the head, in order to create anchor points of the insulation system without the need to introduce areas of weakening in the head. This system is particularly efficient and solves many problems associated with Yankee cylinder insulation. However, it is difficult to apply to cylinders already installed. The application of the welding fixing ring is carried out during an intermediate stage of realization of the Yankee cylinder, so that the stresses and deformations introduced by the welding can be eliminated by means of suitable heat treatments and machining. These operations can only be carried out during construction and, in any case, require properly equipped workspaces; and they cannot be carried out in a Yankee cylinder already installed in a papermaking machine.

Summary of the invention

In order to solve all or part of the problems of the prior art, isolation is provided for

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the end heads of a Yankee cylinder, which has been configured in such a way, that it can be applied to the working Yankee cylinder end heads already installed and, in particular, to the Yankee cylinder end heads that do not they are predisposed to be isolated by means of systems applied during their construction. In accordance with some embodiments, the insulation of the present invention can be applied, in particular, to Yankee steel cylinders, which do not have suitable points, such as screw heads for hugging the end heads to the half-turn, to In order to hold the insulation. In particularly advantageous embodiments, each insulation can be fixed to the respective cylinder head without the need for mechanical treatment.

Basically, in one realization, the isolation comprises, in combination:

- a plurality of insulation panels;

- a clamping ring, divided into at least two portions and attachable to a support and rotation structure of the Yankee cylinder, such that said clamping ring has screw means intended to confine each of said insulation panels in a first position radially more interior;

- for each insulation panel, at least one intermediate clamping element, configured to be secured to at least one screw head arranged in the Yankee cylinder head, at a certain radial distance from the support and rotation structure, thereby that the intermediate clamping element defines at least one clamping point for the respective insulation panel.

In general, the components that allow the Yankee cylinder to be rotatably coupled to the support and rotation bearings are intended for the support and rotation structure. This structure generally comprises, in each head, a pin and a flange. The clamping ring can be made properly to be fixed around the flange of the pin around which the cylinder rotates.

In possible embodiments, each insulation panel protrudes radially beyond said at least one fastening point and has a terminal stop in order to fully contact the Yankee cylinder head to which the insulation is applied.

The insulation may additionally comprise, for each of the intermediate fasteners, a securing member that causes mutual confinement between the intermediate fastener and the respective insulation panel, designed to allow differential thermal deformations of the insulation panel with with respect to the end head. For example, the securing member may comprise, for each fastening point, a screw attachable within a threaded hole of the securing member, and a device against unscrewing; and each insulation panel may exhibit, in correspondence with each fastening point, a hole for the passage of the respective screw, such that said hole has a larger diametral dimension than the diametral dimension of the screw rod passing through el, in order to allow differential thermal expansion between the insulation panel and the intermediate clamping element. In some embodiments, the anti-unscrewing device may comprise a plate coupled to two adjacent screws with the flanges bent in such a way, that they prevent the rotation of the screws.

Different devices can be used against unscrewing.

For example, the anti-unscrewing device may comprise an anti-unscrewing cockpit that interacts with the screw head and with a groove, that is, a hole made in the insulation panel.

In some embodiments, each of the intermediate fasteners comprises a first clamping screw with a first housing that can be coupled with the head of a screw disposed in the cylinder head of the Yankee cylinder. In some embodiments, at least some of the intermediate fasteners comprise a second clamping screw with a second housing intended to engage with the head of a screw disposed in the cylinder head of the Yankee cylinder.

The intermediate fasteners, or at least some of them, may comprise one, two or a plurality of appendices, each of which constitutes a respective fastening point for the respective insulation panel. For example, the intermediate fasteners may have a symmetrical shape, that is, they may have a fork shape, with two appendages or extensions that, extending from a central body or leg, intended to be fixed to one or two respective screw heads arranged in the cylinder head, they extend so that they constitute fastening points that are radially separated from the axis of the Yankee cylinder to which the insulation panels are to be fixed.

In some embodiments, each insulation panel has two radial edges that are preferably rectilinear. The two anchor points for fastening the insulation panel to the intermediate fastening element are preferably adjacent to radial edges of the insulation panel, in order to provide a more efficient and reliable fastener that acts in an area where it has been endowed with rigidity through the appropriate profiles.

In some embodiments, each insulation panel comprises a radially innermost edge, developed

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as an arc of clrcuio, provided with holes for the passage of screws intended for fastening the panel insulation to the clamping ring. In addition, each insulation panel may comprise a radially outermost edge, also, preferably, circularly. Between the radially outermost edge and the radially innermost edge, each panel may have two substantially straight radial edges extending from the radially innermost edge to the radially outermost edge. Advantageously, the intermediate fixing points are arranged in an intermediate position between said radially innermost edge and said radially outermost edge, preferably near the straight edges.

In some embodiments, each of said insulation panels comprises a plate that forms an annular crown segment, which forms a radially outermost circularly shaped edge, a radially innermost circularly shaped edge and two substantially straight radial ones. Advantageously, along each substantially straight radial edge a respective profile is applied which has an approximately orthogonal wing to the plate and located facing the cylinder head to which the insulation is applied. Said wing allows to give rigidity to the structure of the panel.

In possible embodiments, for each insulation panel, a first profile applied along one first of said radial edges protrudes with respect to said first radial edge, and a second profile applied along one second of said radial edges has been arranged backwards with respect to the second radial edge. On the other hand, through the second radial edge and the second profile, through holes have preferably been made in said plate for the passage of screws intended to join the radial edges of adjacent insulation panels. The union screws inserted in the through holes of a first insulation panel are coupled within threaded holes arranged in the first profile of a second adjacent insulation panel.

Along the radially outermost circular edge, an element provided with a certain profile can be applied, for example, with an L-shaped cross section, which has an approximately orthogonal wing to said plate and, possibly, provided with an element of obturation.

The sealing element constitutes a bearing that forms a tight seal against the outer surface of the Yankee cylinder head.

The plate of each insulation panel may have a layer of thermally insulating material applied to the surface of the plate, which, when the panel is applied to the Yankee cylinder, is disposed facing the respective cylinder head.

In order to allow easy application to an already installed Yankee cylinder, the clamping ring is made of more portions and, preferably, of two substantially equal portions, joined together by clamping screws, preferably tangential.

In order to obtain a better mutual union and, therefore, a greater mechanical resistance, in advantageous embodiments, the insulation panels have been shaped and sized to be arranged with one another partially overlapped along the respective radial edges .

The object of the invention is also a Yankee cylinder comprising a cylindrical half-turn, two cylinder end heads and support and rotation structures extending from said end heads axially outward, such that said cylinder comprises, in each one of said end heads, an insulation that has one or more of the previous characteristics. In particular, the Yankee cylinder comprises end heads joined with the half-turn only by welding, without using screws. Preferably, the Yankee cylinder includes an internal bar that joins the two end heads, attached to the latter by means of screws, to which the intermediate fasteners of the insulation panels can be fixed.

The previous summary description defines some characteristics of the various embodiments of the present invention for a better understanding of the detailed description that follows and for the purpose of better evaluating its contribution to the state of the art. Of course, there are other features of the invention that will be described below and that will be set forth in the accompanying claims, which also form an integral part of the description. In this regard, before explaining in detail the various embodiments of the invention, it is understood that the various embodiments of the invention are not limited in their application to the constructive details and the disposition of the components set forth in the following description or They illustrate in the drawings. The invention is susceptible to further embodiments and can be put into practice and carried out in various ways. It is further understood that the phraseology and terminology used herein are for descriptive purposes and should not be regarded as limiting.

Moreover, those skilled in the art will appreciate that the concept on which this disclosure is based can be easily used as a basis for the design of other structures, methods and / or systems to carry out the various purposes of the present invention. Therefore, it is important to consider the claims so that they include such equivalent embodiments, insofar as they do not differ from the spirit and scope of the present invention.

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Brief description of the drawings

A more complete appreciation of the embodiments of the invention described herein and of the majority of advantages related thereto, will be better understood with reference to the following detailed description, taken in combination with the accompanying drawings, in the which:

Figure 1 shows a longitudinal section of a Yankee cylinder without insulation;

Figure 2 shows a front elevation view of an insulated insulation panel;

Figures 3, 4 and 5 show local sections taken, respectively, along lines III-III, IV-IV and V-V of Figure 2;

Figure 6 shows a front elevation view of the clamping ring, isolated;

Figure 7 shows a local section taken along line VII-VII of Figure 6;

Figure 8 shows an enlarged view of a detail taken along line VIII-VIII of Figure 6;

Figure 9 shows an enlarged view of the area indicated by IX-IX in Figure 6;

Figure 10 shows a front elevational view of an isolated intermediate clamping element;

Figure 11 shows a view taken along line XI-XI of Figure 10;

Figure 12 shows a front elevation view according to line XII-XII of Figure 1 of the Yankee cylinder, with the insulation installed;

Figure 13 shows a section taken along line XIII-XIII of Figure 12;

Figures 14 and 15 show extensions of details XIV and XV of Figure 13;

Figure 14A shows a view taken along line A-A of Figure 14;

Figure 16 shows an enlargement of detail XVI of Figure 12;

Figure 17 shows an enlargement of detail XVII of Figure 13;

Figure 18 shows a section taken along line XVIII-XVIII of Figure 12.

Detailed description of embodiments of the invention

The following detailed description of embodiments provided by way of example refers to the accompanying drawings. The same reference numbers used in the different drawings represent identical or similar elements. The drawings are not necessarily to scale. In addition, the following detailed description does not limit the invention. On the contrary, the scope of the invention is defined by the accompanying claims.

Throughout the description, the reference to "one embodiment" or "some embodiments" means that a particular feature, structure or properties described in connection with one embodiment, are included in at least one embodiment of the described object. Therefore, the use of the phrase "in one embodiment" or "some embodiments", or of similar expressions or having an equivalent meaning in different places of the description, will not necessarily refer to the same embodiment or the same embodiments. On the other hand, the particular characteristics, structures or properties can be combined in any suitable way, in one or more embodiments.

In Figure 1, a Yankee 2 cylinder has been shown in its entirety, in a longitudinal section containing the A-A rotation axis of the cylinder itself. In this Figure, the Yankee cylinder lacks insulation. The Yankee 2 cylinder comprises a main body 1 ace! as support and rotation structures 3, through which the cylinder 2 is supported, by means of supports 5 and 7 of support bearings, through a fixed structure, not shown. Through the support and rotation structures 3, a heat transfer fluid, typically a steam, is circulated so that it fills the inner chamber of the Yankee cylinder. The latter has been carried out inside the body 1 of the Yankee cylinder. The body 1 of the Yankee cylinder 2 may comprise a cylindrical half-turn 11 formed from a calendered plate and with welded edges along a generatrix or along an inclined helical line existing on the surface of the Yankee cylinder itself.

The cylindrical half-turn can also be performed by associating two or more cylinders of a smaller size, obtained by winding and welding a plate. In this case, the association between two adjacent cylindrical half-turns can be carried out by means of a circumferential weld, in case the contact takes place in a plane orthogonal to the axis of the half-turn, or by means of an elliptical weld,

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if the contact takes place in an inclined plane with respect to the axis of the half-turn. The cover 11 is joined, at its ends, to two end heads 13 and 15, to which the support and rotation structures 3 are fixed, as described later in this specification.

In an advantageous embodiment, the support and rotation structures 3 each have a flange 3A attached, for example, by means of screws 16 to the respective end heads 13 and 15. The screws 16 are arranged in a circular arrangement around holes 13A and 15A made in the end heads 13 and 15. The respective pins 18 rotating inside the bearing bearings 5 and 7 extend axially outwardly from the flanges 3A, orthogonally to the heads of end 13, 15. The pins 18 may be axially perforated for the passage of a heat transfer fluid, usually a vapor.

In some embodiments, the interior surface of the calendered plate constituting the cylindrical half-turn 11 has been provided with a plurality of annular grooves 11A in which the condensation due to the transfer of thermal energy from the steam injected into the chamber is collected existing inside body 1 of Yankee 2 cylinder, to the outside environment. Figure 1 shows only some of the grooves 11A, near the end heads 13, 15, but it should be understood that, normally, the grooves are uniformly distributed throughout the longitudinal development of the Yankee 2 cylinder. In a manner itself known and not shown, the condensation is aspirated from the bottom of the annular grooves 11A and made recircular. According to other embodiments, the inner surface of the cylindrical half-turn is not grooved.

According to an advantageous embodiment, the cylindrical half wrap 11 is joined to the end heads 13 and 15 by means of a weld made with circular weld beads 20.

In some embodiments, such as the one illustrated, within the Yankee 2 cylinder a transverse armature 21 is provided that extends from one to the other of the end heads 13, 15. In some embodiments, the transverse armor 21 has a structure cylindrical 21A with annular end flanges 21B through which the ends of the transverse reinforcement 31 are anchored to the end heads 13 and 15. In the illustrated embodiment, the transverse reinforcement 21 is fixed to the end heads 13, 15 by means of two sets of screws for each end head, arranged in accordance with two circular arrangements around the AA axis of the Yankee cylinder 2. The screws have been indicated with references 23 and 25, such that the screws 23 they are arranged along a circumference of a smaller diameter and the screws 25 have been arranged along a circumference of a larger diameter.

As shown in Figure 1, in which the Yankee cylinder has been shown without insulation, the surface of each end head 13, 15 lacks anchors for insulation, with the exception that the flange 3A of each structure of support and rotation 3 and with the exception of screws 23, 25. Moreover, all these elements are located within an annular zone of radius R1, which is substantially smaller than the total radius R2 of the Yankee cylinder. In the outer annular crown of width equal to R2-R1, the end heads 13 and 15 do not exhibit elements to hold the insulation and it is therefore necessary to provide a system to hold the insulation that can be applied to the Yankee 2 cylinder even when the latter has already been installed and inserted inside a fixed structure within which bearings 5 and 7 are housed.

An embodiment of an insulation according to the invention, applicable to a Yankee 2 cylinder of the type described above will be explained in the following, with reference to Figures 2 to 18.

A first component of the insulation is constituted by an insulation panel 51. The complete isolation of each individual end head 13, 15 comprises a plurality of such insulation panels, partially overlapped and joined together. As can be seen, in particular, in Figure 12, in the embodiment shown there are provided ten insulation panels 51, nine of which are identical to each other and one more has an opening for access to a mouth of record 52 (Figure 1) possibly presenting the Yankee 2 cylinder.

In other embodiments, the number of insulation panels may be different from that illustrated. On the other hand, in some embodiments, all panels can be identical to each other, without openings for access to the manhole. In some cases, the manhole has been provided only on one of the end heads and, then, the panel, with a corresponding opening, will be applied only on one side of the cylinder.

As shown in Figures 2 to 5, each insulation panel 51 is substantially in the form of an annular ring segment defined by two radial edges and two circular edges, interior and exterior.

The insulation panel 51 may comprise a plate 53 forming the main body of the panel 51, to which a thermally insulating material is applied, for example, consisting of one or more cushions of thermally insulating material, such as a mineral wool or wool of glass. The insulating material has been shown only schematically and partially in Figure 13, in which it has been indicated with the reference "I". In the remaining figures it has been omitted for the sake of clarity.

In the illustrated embodiment, the plate 53 has a radially innermost edge 53A and a radially larger edge

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exterior 53B. The two edges 53A, 53B have the shape of an arc of circumference, and are concentric with each other and are concentric with respect to the axis AA of the Yankee 2 cylinder in which the panel 51 is applied. The plate 53 also has a first substantially straight radial edge 53C, as! as a second substantially straight radial edge 53D.

Along the first substantially straight radial edge 53C a first element 55 provided with a certain profile is applied. In the illustrated embodiment, the element 55 provided with a certain profile has an L-shaped cross section, with a first wing 55A and a second wing 55B. The first wing 55A extends substantially perpendicular to the plane of the plate 53, while the second wing 55B extends substantially parallel to the plane of the plate 53. The first element 55 provided with a certain profile is fixed to the plate 53 by means of a plurality of screws 57 and lock nuts and nuts 59, as shown in detail in Figure 5. The wing 55B of the element 55 provided with a certain profile can be coupled between the plate 53 and a flat element 61 provided with a certain profile, which is disposed cuddled against the L-shaped element 55 such that the wing 55B remains locked between the plate 53 and the flat element 61 provided with a certain profile. At appropriate intervals, parallel to the first rectilinear edge 53C of the plate 53, in the wing 55B of the respective element 55 provided with a certain profile, there are threaded holes 63 that also extend into the flat element 61 provided with a certain profile (see again Figure 5). The threaded holes 63 have been made in a part 55B of the wing of the element 55 provided with a certain profile, which protrudes with respect to the edge 53C.

Along the substantially straight and opposite edge 53D of the plate 53, by means of the screws 65 and the nuts 67, a second element 69 is provided with a certain profile, for example, with an L-shape, comprising a first wing 69A substantially orthogonal with respect to the plate 53 and a second wing 69B substantially parallel to the plate 53. The element 69 provided with a certain profile is mounted behind the edge 53D of the plate 53 such that the plate 53 protrudes in a certain amount with respect to the element 69 provided with an L-shaped profile. In the embodiment illustrated, along the portion of the plate 53 protruding beyond the element 69 provided with a certain profile, between the latter and the edge 53D of the plate, there are through holes 71 for screws that allow mutual locking between adjacent and partially overlapping insulation panels 51, with a provision that will be described in greater detail with reference to the F Figure 18.

In the illustrated embodiment, along the radially innermost circular edge 53A, the plate 53 has a plurality of through holes for locking the insulation panel 51 with respect to an embracing ring described in the following.

Along the radially outermost edge 53B, and approximately in alignment with or slightly behind (Figure 3) with respect to said edge 53B, on the inner surface of the plate 53, an additional element 75 provided with a certain profile, preferably an element provided with an L-shaped profile, with a first wing 75A substantially orthogonal to the plane in which the plate 53 extends, and a second wing 75B substantially parallel to the plate 53 and which is in contact with the inner surface of the plate itself, that is, with the surface facing the corresponding end head 13, 15 of the Yankee cylinder 2 when the insulation is installed. In the example shown, the profile 75 is fixed to the plate 53 by means of screws 77 and nuts 79.

In other embodiments, elements 55, 69, 75 provided with a certain profile may have a different cross-section than that shown here. For example, they may have an L-shaped section with different wings from each other, or at least some of these elements provided with a certain profile may have been shaped in an I or H shape. In the embodiment illustrated On the other hand, the elements endowed with a certain profile have an identical section. This may provide advantages in terms of economics of supply, fabrication and storage, but the possibility of making use of elements provided with profiles shaped in different ways is not excluded.

In the embodiment illustrated, the elements 55 provided with a certain profile 69 and 75 have been fixed to the plate 53 by means of screws. In other embodiments, not shown, other fixing means may be used. For example, the elements 55, 69 and 75 provided with a certain profile can be fixed to the plate 53 of the insulation panel 51 by welding, riveting or other suitable means. It is also possible to make use of different fixing methods in different elements provided with a certain profile of the same panel, or for the elements provided with a certain profile of different panels.

In the illustrated embodiment, the insulation system according to the invention comprises, for each head 13, 15 of the Yankee cylinder 2 to be insulated, apart from a plurality of insulation panels 51 as described above and illustrated, in In particular, in Figures 2 to 5, a clamping ring generally indicated with the reference number 81 and shown, in particular, in Figures 6 to 9. The clamping ring 81 has been designed to be arranged embraced in the flange 3A of the support and rotation structure 3 of the corresponding end head 13 or 15 of the Yankee 2 cylinder.

Preferably, in order to allow the mounting of the clamping ring 81 in the Yankee cylinder 2 when it has already been installed in the production line, the clamping ring is constituted by two or more portions or parts that can be held between them. In the embodiment illustrated, see in particular, Figure 6, the clamping ring 81 is divided into two portions 81A that are substantially identical to each other. The two portions 81A

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they are mutually opposite to each other by means of screws arranged in diametrically opposite areas in which the ends of the two portions 81A of the clamping ring 81 are opposite each other. More specifically, with reference 83 two more inner screws have been indicated, and with reference 85, two more outer screws, tangentially mounted in diametrically opposite positions orthogonally to two surfaces facing each other and belonging to the two portions 81A of the clamping ring 81.

In some embodiments, along the circumferential surface of the clamping ring 81 there are holes for fixing the insulation panels 51. In some advantageous embodiments, the holes 87 are threaded holes. The threaded holes 87 may be through threaded holes, that is, threaded holes that cross the entire thickness of a radially outermost annular area of the portions 81A of the fastening ring 81, as shown in the drawings. The threaded holes 87 are accessible for screwing screws 88 (see, in particular, Figures 12 and 15) intended to block the insulation panels with the flat side 81B of the clamping ring 81.

As shown, in particular, in Figures 12 and 13, the clamping ring 81 is arranged around the flange 3A and in the respective support and rotation structure 3 of the end head 13 or 15. Of this Thus, as will be clear in the following, the insulation panels 51 can be fastened with their radially innermost circumferential edges 53A along the clamping ring 81, which, in turn, is disposed around the flange 3A of the support and rotation structure 3.

In the illustrated embodiment, the insulation system additionally comprises, for each insulation panel 51, at least one intermediate fastener, such that one of them has been shown individually in Figures 10 and 11 and is generally indicated by the reference numeral 91. In the example illustrated, the intermediate clamping element 91 comprises a pin or rod 93 from which two appendages 95 and 97 protrude which are substantially symmetrical with respect to a central plane whose trace has been indicated by pp ( Figure 10). Accordingly, the intermediate fastener element has, in this embodiment, approximately the shape of a fork. Other embodiments are also possible as will be apparent from the following, even though the form now illustrated is particularly effective.

In the illustrated embodiment, the rod 93 defines a first housing 99 and a second housing 101 for the coupling of the intermediate fastening element 91 respectively to the heads of the screws 25 and 23 with which the transverse reinforcement 21 is fixed to the heads of end 13 and 15. In the embodiment illustrated, the first housing 99 and the second housing 101 have a circular shape and are formed by elastically deformable portions of the pin 93.

More particularly, the housing 99 is partially delimited by an elastically deformable appendix 99A intended to tighten the housing 99 around the head of the corresponding screw 25, purpose for which the pin 93 has a notch 99B. In the same way, the housing 101 is delimited by two portions 101A, 101B separated by a notch 101C in order to tighten the housing 101 around the head of the corresponding screw 23. The tightening of the two housings 99 and 101 around the screw heads 25 and 23 take place by means of corresponding screw members 103 and 105, visible, in particular, in Figure 16.

In this way, each intermediate clamping element 91 can be fixed on the corresponding end head 13 or 15 of the Yankee 2 cylinder, in such a position, that appendices 95 and 97 extend away from the AA axis of the Yankee 2 cylinder, in the direction of the peripheral edge of the respective end head, in order to define anchor points for isolation arranged at a certain distance from the AA axis of the Yankee cylinder 2 which is greater than the radial distance of the screws 23, 25 used to fix the internal transverse reinforcement of said Yankee 2 cylinder.

Each appendix 95, 97 has, in proximity to its distal end 95A, 97A (ie, the opposite end of the pin 93), a respective threaded hole 107, 109. The threaded holes 107, 109 allow the use of screws of assembly 111 whereby each insulation panel 51 is fixed in an intermediate position to the intermediate fastening element 91, and, through the latter, to the respective end head 13 or 15.

In the assembled configuration (Figures 12 and 16), the intermediate fasteners 91 are located in such a way that the threaded holes 107, 109 are aligned with the holes 73 of the insulation panels 51. More specifically, each element of intermediate fastener 91 is located with holes 107, 109 in alignment with holes 73 of a respective insulation panel 51, such that, for end head, a number of intermediate fasteners 91 equal to the number of panels will be used of insulation 51. In other embodiments, the possibility of using a different number of intermediate fasteners for each insulation panel is not excluded, for example, two intermediate fasteners, one for each hole 73, possibly anchored to different pairs of screws 23, 25. In some embodiments, there may be two or more intermediate fasteners for each insulation panel 51, fixed to different screws. 23, 25, for example, an intermediate clamping element fixed to a screw 23 and another intermediate clamping element fixed to a screw 25. In further embodiments, an intermediate clamping element secured only to a respective screw can also be provided only 25, or just one screw 23, or two screws 23 but not the

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screws 25, or vice versa, to screws 25 and not to screws 23.

Even in the case of a fork-shaped intermediate fastener 91 such as that shown in Figure 10, the fastener may have been provided only in one of the screws 25, 23, instead of both as in the embodiment illustrated in the drawing.

In some embodiments, the screws 111 used to secure each insulation panel 51 to the respective intermediate fastener element 91 have a particular shape shown in detail in Figure 14. These screws have a preferably hexagonal head 111A, of large dimensions with respect to to leg 111B, which extends into a threaded pin 111C. The threaded pin 111C has a length such that it does not protrude from the threaded hole 107, or 109, but remains inside it. In this way, in the case of a complete tightening of the screw, the upper stop formed by the larger diameter portion of the bar 111B touches the outer surface of the intermediate clamping element 91 before the threaded pin 111C comes into contact with the end head surface. If this is not the case, the screw could push and move the intermediate fastener 91, acting as an extraction screw. The diameter D of the rod 111E is advantageously smaller than the diameter D0 of the through hole 73 of the insulation panel 51. In this way, as can be understood by observing the local cut of Figure 14, the insulation panel 51 and, in particular, the plate 53 supporting the thermally insulating material may have a different thermal expansion from that of the intermediate fastening element 91. This different thermal expansion may be determined not only by the different materials used for these two components, but also, and above all, because they are at substantially different temperatures from each other: the intermediate clamping element 91, being in contact with the respective end head 13 or 15, is at a higher temperature than that of the plate 53 which constitutes the outer part of the insulation panel 51. The better the insulation, the greater the temperature difference between the interlocking element gave 91 and plate 53 of the insulation panel 51. The difference between the diameters D and D0 allows the intermediate clamping element 91 to be stretched and then radially stretched outward in an amount greater than the expansion of the plate 53.

In some embodiments, as shown, in particular, in Figure 14, a particular system against unscrewing has also been provided, intended to prevent the screws 111 from loosening, for example, as a consequence of the dynamic stresses at which The Yankee 2 cylinder is subjected. Figure 14A shows schematically, in a view taken along the line AA of Figure 14, an embodiment of the system against unscrewing. In this case, two screws 111 inserted in adjacent holes 73 of two adjacent insulation panels 51, are blocked by a common plate 112, for example, rectangular in shape, which has two holes through which the two screws 111 pass Two opposite vertices 112A of the plate 112 are bent against the respective faces of the two hexagonal heads of the screws 111, such that they lock both screws against any accidental unscrewing.

Figure 14 shows the detail of a reinforcement plate 53P applied on the face of the plate 53 of the insulation panel 51 facing towards the end head to which the insulation panel 51 is fixed. The reinforcement plate 53P is, advantageously, perforated in correspondence with the hole 73 in order to allow the passage of the pin 111B of the screw 111.

The overall insulation formed by the elements described so far is shown in detail in the assembled configuration of Figures 12 to 18. Each of the two end heads 13, 15 is coated with an insulation formed by a plurality (ten, in the illustrated example) of insulation panels 51 that are partially overlapped at the straight radial edges, as shown in the detail of Figure 18. In this detail, it shows a local cut taken along line XVIII- XVI11 of Figure 12, a locking screw 121 has been shown advantageously provided with a rosette 123 against unscrewing and inserted into each threaded hole 63 of which it has been provided, such that the element 55 provided with a certain profile, which forms the outer radial edge of the panel itself, protrudes with respect to the edge 53C of the sheet 53. In the assembled configuration, each threaded hole 63 of the element 55 provided with a shaped profile of L and belonging to an insulation panel 51, is aligned with a corresponding hole 71 formed along the edge 53D of the plate 53 of the adjacent panel. In this way, each pair of adjacent insulation panels 51 are joined together in the area where the protruding portion of the panel 53 of a panel overlaps the element 55 provided with a certain profile and belonging to the adjacent panel, by means of the insertion of a series of screws 121 in the through holes 71 of a panel and its screwed into the corresponding threaded holes 63 made in the wing 55B of the element 55 provided with a certain profile and in the reinforcement plate 61 of the insulation panel 51 adjacent.

The panels are also fixed by the screws 88 at the radially innermost edges 53A of the clamping ring 81, in turn fixed by means of the screws 83, 85 tangentially to the flange 3A of the respective support and rotation structure 3.

Finally, in an intermediate position, along the intermediate circumference 53M, each insulation panel 51 has been fixed, in correspondence with the fastening points defined by the holes 73, by means of the screws 111, to the fastening element fork-shaped intermediate 91, in turn locked by means of screws 103 and 105 in the heads of screws 25 and 23 used to mount the transverse frame 21 inside the

Yankee cylinder 2.

Each insulation panel 51 extends radially outwardly beyond the circumference 53M, substantially to the peripheral edge of the respective end head 13, 15. The locking carried out by means of the screws 111 at the intermediate anchor points defined by the holes 73, and the fastening by means of the screws 88 along the clamping ring 81, allow the insulation to be so! formed remains adhered to the end head 13, 15. In addition to the fastening carried out by means of screws 111 and screws 88, the blocking of the insulation formed by partially overlapping panels 51 is also achieved through the support offered by the elements provided with an L-shaped profile 55, 61 and 75. In particular, the curved profiles 75 that follow the radially outermost circular edge 53B of the individual insulation panels 51, can advantageously be equipped, in the wing 75A, with a gasket 127 (see detail in Figure 17), which forms a support and a seal against the outer surface of the end head 13 or 15 to which the individual insulation panel 51 is anchored.

It is understood that what has been illustrated and described represents only possible non-limiting embodiments of the invention, which may vary in configurations and arrangements without departing from the scope of the concept underlying the invention. The presence of any reference numbers in the accompanying claims has the sole purpose of facilitating the reading of the preceding description and the accompanying drawings, and in no way limits the scope of protection.

Claims (17)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 1. - An insulation for the end heads (13, 15) of a Yankee cylinder (2), comprising: - a plurality of insulation panels (51); - a clamping ring (81), divided into at least two portions (81A) and attachable with a support and rotation structure (3), such that said clamping ring has clamping members (88) to confine each one of said insulation panels in a radially inner first position; - for each insulation panel (51), at least one intermediate clamping element (91), configured to be confined to at least one head of a screw (111) provided in the end head (13; 15) of the Yankee cylinder (2), at a certain radial distance from said support and rotation structure (3), such that said intermediate fastening element (91) defines at least one fastening point for the respective insulation panel (51). 2. - An insulation according to claim 1, wherein said fastening members (88) for confining each insulation panel (51) to said fastening ring (81) in a first radially inner position, are screw members . 3. - An insulation according to claim 1 or claim 2, wherein each insulation panel (51) extends radially beyond said at least one fastening point and has an end support, intended to rest against the end head (13; 15) of the Yankee cylinder (2) on which the insulation is mounted. 4. - An insulation according to claims 1, 2 or 3, which also comprises, for each of said intermediate fasteners (91), a mutually confining member between the intermediate fastener (91) and the panel of respective insulation (51), configured to allow differential thermal deformations of the insulation panel (51) with respect to the end head (13; 15). 5. - An insulation according to claim 4, wherein said confinement member comprises, for each fastening point, a screw (111) attachable within a threaded hole (107; 109) of said confinement member and a self-locking device (112); and each insulation panel (51) has, at each fastening point, a hole for the passage of the respective screw (111), such that said hole has a diametral dimension (D0) that is greater than the diametral dimension (D ) of the screw pin (111) that passes through it, in order to allow a differential thermal expansion between the insulation panel (51) and the intermediate clamping element (91). 6. - An insulation according to claim 5, wherein said self-locking device (112) comprises self-locking members that interact with the heads (111A) of two of said adjacent screws. 7. - An insulation according to one or more of the preceding claims, in which each of said intermediate fasteners (91) comprises a first screw clamping device with a first seat (99) attachable with the head of a screw (25) located at the end head of the Yankee cylinder (2), such that at least some of said intermediate fasteners (91) comprise a second screw clamping device with a second seat (101) attachable with the head of a screw (23) located at the end head of the Yankee cylinder, and such that at least some of said intermediate fasteners comprise a rod (93) forming said two screw clamping devices, and at least a first extension (95) forming said at least one fastening point of a respective insulation panel (51). 8. - An insulation according to claim 7, wherein at least some of said intermediate fasteners (91) comprise a second extension (97) forming an additional fastening point of the respective insulation panel (51). 9. - An insulation according to claim 8, wherein said insulation panels (51) each have two radial edges (53C, 53D) and in which the two fastening points of the insulation panel (51) to the intermediate fastening element (91) are located adjacent to the radial edges (53C, 53D) of the insulation panel (51). 10. - An insulation according to one or more of the preceding claims, in which each insulation panel (51) comprises: a radially inner edge (53A) with a spherical arc extension, provided with holes for the passage of fixing screws (88) to said fastening ring (81); a radially outer edge (53B) with a circular extension; two substantially straight radial edges (53C, 53D), extending from the radially inner edge (53A) to the radially outer edge (53B), such that said at least one intermediate fastening point is in an intermediate position between said radially inner edge (53A) and said radially outer edge (53B). 11. An insulation according to one or more of the preceding claims, wherein said panels of 5 10 fifteen twenty 25 Insulation (51) comprises a plate (53) forming an annular ring segment, with a radially outer edge (53B) having a circular extension, a radially inner edge (53A) having a circular extension, and two substantially radial radial edges rectilinear (53C, 53D), and in which, along each of said substantially straight radial edges, a respective profile (55) having a wing (55B) approximately orthogonal to said plate, located face-to-face has been mounted to the end head (13; 15) on which the insulation is mounted. 12. - An insulation according to claim 11, in which, for each insulating panel (51), a first profile (55) mounted along a first of said radial edges protrudes with respect to said first radial edge, and a second profile (69) mounted along one second of said radial edges has been arranged delayed with respect to the second radial edge; and in which, between the second radial edge and the second profile, through holes have been made in said plate for the passage of connecting screws of the radial edges of insulating panels (51) adjacent to each other, such that said Union screws, which are inserted through the holes of a first insulating panel (51), are coupled in threaded holes provided in the first profile of a second adjacent insulating panel (51). 13. - An insulation according to claim 11, in which, along said radially outer edge with circular extension, a profile (75) having a wing (75A) approximately orthogonal to said plate has been mounted. 14. - An insulation according to claim 13, wherein said profile (75) mounted along the radially outer edge of each insulation panel (51), is provided with a seal (127). 15. - An insulation according to one or more of the preceding claims, wherein said clamping ring (81) is formed by at least two substantially equal portions, joined together by means of tangential clamping screws (83; 85 ). 16. - An insulation according to one or more of the preceding claims, wherein said insulation panels (51) are structured and sized to be arranged partially overlapped with each other along the radial edges. 17. - A Yankee cylinder (2) comprising a cylindrical half-turn (11), two end heads (13, 15) and support and rotation structures (3) extending axially outward with respect to said end heads, such that said cylinder (2) comprises, in each of said end heads (13, 15), an insulation according to one or more of the preceding claims.