FI12166U1 - Drying cylinder of a fibrous web machine - Google Patents

Description

FIBER DRYING CYLINDER

The invention relates to a drying cylinder for a fiber web machine, the steel sheath being supported by an end piece and the sheath being secured by a welding joint.

In the drying section of the fiber web machine, the drying cylinders are heated with pressurized steam. In addition to cast iron, drying cylinders are also made of steel, which is stronger than cast iron. In this case, the wall of the jacket can be made thinner than by making cast iron. At the same time, the drying cylinder becomes considerably lighter than cast iron. Thus, a lighter backbone can be used. In addition, the thermal conductivity of steel is 10-30% better than that of cast iron. Hereby, at the same vapor pressure, a higher jacket surface temperature is achieved and thus a higher drying efficiency than the cast iron cylinder. Despite the increase in drying power, the drying section remains almost unchanged in structure and requires the same space as before. The steel sheath is supported by an end piece at each end of the drying cylinder.

In a known drying cylinder, the steel sheath is secured to the end piece by welding and may have a relief groove in the end piece to reduce tension. In practice, each end piece is welded directly to a cylindrical jacket. In addition to welding itself, the lightening groove allows inspection of the welding joint.

If the cylindrical sheath of the drying cylinder requires internal machining, the machining must be performed prior to welding the end piece to the sheath. In addition, once the end piece has been secured, machining the weld joint from within the dryer cylinder is impossible. The welded joint is also heat-treatable, which requires appropriate professional skills and equipment. In the prior art, this is time consuming due to the solid and massive end piece. At the same time, heat treatment and inspection of the welded joints extend the lead time in manufacturing. Heat treatment itself increases the risk of deformation of the drying cylinder and the possible need for machining the inside.

The object of the invention is to provide a new type of drying machine for a fiber web machine which is more durable and simpler and faster to manufacture. Characteristic features of the drying cylinder of the present invention will be apparent from the appended claims. In the drying cylinder of the invention, the steel sheath can be fabricated, welded, post-treated and checked prior to attachment of the end piece. In addition, various end pieces can be used. Cast-iron diapers can also be replaced with steel diapers while the rest of the drying cylinder structure remains unchanged. Regardless of the application, the end piece can later be removed without breaking the weld.

The invention will now be described in detail with reference to the accompanying drawings, in which:

Fig. 1a shows a cross-sectional end of a prior art drying cylinder,

Figure Ib shows a partial magnification of Figure la,

Figure 2 shows a first embodiment of a drying cylinder according to the invention,

Figure 3 shows another embodiment of a drying cylinder according to the invention.

Fig. 1a shows a prior art fiber drying machine 10, more particularly one end of a drying cylinder 10. The drying cylinder 10 has a steel sheath 11 supported by an end piece 12. Here the end piece is machined from sheet material and the end piece further comprises a rope groove 13. The end piece may also be a steel casting piece, but the invention may also have cast iron. In the embodiment shown, the sheath has a thickness of 20 mm, whereby the heat of the steam is effectively transferred through the thin steel sheath to the fibrous web. The end piece 12 has a bolted hollow projection shaft 14 for bearing. The hollow of the projection shaft allows the steam to be introduced into the drying cylinder and the condensate to be removed from the drying cylinder respectively.

For maintenance, the drying cylinder includes a manhole. In this case, maintenance operations, such as height adjustment of the siphon, can be performed inside the drying cylinder. The end piece 12 of Fig. 1a comprises two manholes 15 arranged symmetrically with respect to the axis of rotation 16 of the drying cylinder 10. The effects of the parts removed from the end piece on the balance of the drying cylinder are then compensated.

Ib also shows a lightening groove 17 machined into the end piece 12. The lightening groove 17 is made so deep that the weld joint 18 between the sheath 11 and the end piece 12 can be welded while ensuring the dynamic strength of the weld joint. The sheath itself is thin and can be made of bent sheet steel pieces, for example one to four pieces.

2 and 3 are thus supported by an end piece 12. In addition, the sleeve 11 is secured by a welding joint 18 to the extension 19 of the invention. between extension 19 and diaper 11. The extension provides many advantages in the construction of the drying cylinder and especially in the manufacture. The extension allows the weld joint to be positioned far enough away from the end piece, which facilitates welding as well as heat treatment and ultimately inspection. Welding is possible on both sides of the sheath, which means that a greater variety of welding structures are used. In addition, the extension gives the weld joint a distance to the end piece, which increases dynamic durability. If necessary, the inner surface of the jacket can be machined, as can the inner lathe after welding and heat treatment.

Another advantage is the attachment of the end piece. In the embodiment shown, there is a bolt joint 20 between the extension 19 and the end piece 12. One bolt 21 is shown in Figure 3. The end piece 12 further has a groove 22 according to the extension 19, whereby the joint is self-centering. At the same time, part of the load is transmitted from the sheath to the end piece without loading the bolt joint.

On the other hand, there may be only a press fit between the extension 19 and the end piece 12. In this case, the deformation of the end piece is transmitted by the compression fitting to the extension welded to the sheath instead of the bolt connection.

In the applications of Figures 2 and 3, a bolt joint 20 is used, for which the extension 19 includes a bore 23. The braid is an integral part of the extension which externally faces the shape of the sheath but is internally shaped to minimize the indentation effect. The joint is shaped and dimensioned according to the jacket and end piece. More generally, the extension can be freely shaped as required. In practice, the extension may be a sheet structure, a bend or a steel casting. In this case, a suitable extension can be selected for each application and position, the sheath itself being a universal sheath.

In the embodiment of Figure 2, the extension 19 is thin, whereby the weld joint 18 is easy to weld. At the same time, despite the extension, the inner surface of the sheath 11 can be machined. In this case, the end piece 12 comes to the end of the extension 19. The embodiment of Fig. 3 has a thicker throat 23 and the end piece 12 enters the extension 19. In this case, the effect of the extension on the length of the drying cylinder is minor and a compression fit can be used between the extension and the end piece. Further, the thickening 23 includes a lightening groove 17, which gives the drying cylinder more length to effect the steam on the fiber web to be dried at the same outer dimensions of the drying cylinder. Hereby a slightly wider fibrous web can be dried than before.

The above-described extension of the invention accelerates and facilitates the fabrication of a steel jacketed drying cylinder. The extension allows for internal machining of the sheath after welding and heat treatment. Thus, the manufacture corresponds to the normal production chain of the cast iron drying cylinder jacket. In addition, the end piece or cantilever shaft or both are interchangeable thanks to the bolt connection. Despite this extension, the effective drying width of the dryer cylinder remains unchanged. In addition, the sheath of the old cast iron drying cylinder can be replaced with a steel sheath and extension, utilizing existing end pieces and projection shafts. The endpieces may be machined from the sheet or castings.

In both applications, the extension 19 is preferably longer than the material thickness of the prior art welded end piece, whereby the weld joint is obtained sufficiently far from the end piece without compromising on the drying width. In the embodiment of Figure 2, the end piece 12 is an extension of the sheath 11 fastened by a bolt connection 20 to the extension 19. The bolt connection thus corresponds to a cast iron drying cylinder. In this case, the extension and the steel casing according to the invention can be replaced by a cast iron drying cylinder or a simple casing having a bolted end piece. In practice, the cast iron drying cylinder jacket is replaced by a steel jacket. Thus, machine rebuilds can utilize earlier structures while at the same time gaining more drying power.

In the embodiment of Figure 3, extension 19 includes a relief groove 17. This avoids an effective narrowing of the drying width relative to the welded end piece of the jacket. In other words, the end piece does not extend the drying cylinder. The structure according to the invention can thus replace a steel cylinder having an end piece secured by welding.

Thanks to the new design, the diaper alone can be subcontracted, pre-machined internally. The diaper may also be provided with an extension at the time of purchase and ready to be assembled. The weld joint can also be heat treated and checked before attaching the end piece. If necessary, the weld joint can be machined before attaching the end piece.

Together with the bolted connection allows the jacket to be machined before attaching the end piece. The bolted joint also avoids any deformation or deformation that previously occurred due to the welded joint and its heat treatment. The extension allows for a simple construction of the drying cylinder, which can also be easily accessed by a manhole. The extension allows the strength of the steel in the drying cylinder to be utilized as a wall thinner than the cast iron sheath, and thus surprisingly performs bolt attachment to the shoulder or shoulder formed by the thickening. The extension can be used with both steel and cast iron end pieces.

Claims (6)

PROTECTION REQUIREMENTS 1. Fiberbanmaskins torkcylinder, dær manteln (11) av stål stöds med ändstycken (12), och manteln (11), fåst med Svets-förband (18), kännetecknad av att det mellan manteln (11) och ändstycket (12) finns en förlängning (19), och svetsförbandet (18) finns mellan förlängningen (19) och manteln (11). A drying cylinder for a fiber web machine having a steel sheath (11) supported by an end piece (12) and a sheath (11) secured by a welding joint (18), characterized in that an extension (19) is provided between the sheath (11) and the end piece (12). , and the weld joint (18) is between the extension (19) and the sheath (11). 2. Torkcylinder enligt skyddskrav 1, a rotary deck (19) and a rotary (12) finns et bult förband (20). Drying cylinder according to Claim 1, characterized in that a bolt connection (20) is provided between the extension (19) and the end piece (12). 3. Torkcylinder enligt skyddskrav 1 eller 2, kännetecknad av att det mellan förlängningen (19) och ändstycket (12) finns en presspassning. 3. A drying cylinder according to claim 1 or 2, characterized in that a compression fitting is provided between the extension (19) and the end piece (12). 4. Torkcylinder enligt skyddskrav 2 eller 3, kännetecknad av att förlängningen (19) innefattar en kantvulst (23) för bultförbandet (20). Drying cylinder according to claim 2 or 3, characterized in that the extension (19) includes a thickening (23) for the bolt connection (20). 5. Torkcylinder enligt skyddskrav 4, rotating screws (23) innefattar et ursparingsspår (17). A drying cylinder according to claim 4, characterized in that the thickening (23) comprises a relief groove (17). Drying cylinder according to one of Claims 1 to 5, characterized in that the extension (19) is a plate structure, a forge or a steel die. SKYDDSKRAV 6. Torkcylinder enligt något av skyddskraven 1-5, kännetecknad av att förlängningen (19) en skivkonstruktion, Smide eller stålgjutgods.