Drive device for the drying cylinder of a fiber web machine

Abstract

Drive for a drying cylinder (10) of a fiber web machine, which - a frame (16) with a bearing housing (23) which serves to support the cylinder (10) via its shaft (13) on a foundation, - a drive transmission (18) serving to transmit a drive force required for rotating the cylinder (10) to the cylinder shaft (13), which has a gear transmission (26, 28) and a transmission housing (20) in which the gear transmission (26, 28) is mounted, and - means (22) arranged on the frame (16) for attaching a steam supply and / or condensate drain line (14, 15) to the bearing housing (23) supporting the cylinder (10), characterized in that - the drive transmission (18) consists of a shaft-mounted transmission arranged on the cylinder shaft (13) between a face disk (12) of the cylinder (10) and the frame (16), wherein the drive transmission (18) is supported on the foundation only by a moment support, and - the gearbox housing (20) and the bearing housing (23) are coupled to each other in a way that allows small angular changes of the drive gearbox (18) to the frame (16).

Description

[0001] The subject of this invention is a drive device (hereinafter referred to as drive) intended for a drying cylinder of a fiber web machine, which - a frame with a bearing housing for rotatably supporting the cylinder via its shaft, - a drive transmission for transmitting the driving force required to rotate the cylinder to the cylinder shaft, comprising a gear transmission and a gearbox housing in which the gear transmission is mounted and - includes means arranged in conjunction with the frame for connecting a steam supply and / or a condensate drainage line to the bearing housing of the cylinder.

[0002] In this context, a fiber web machine refers to a paper, cardboard or tissue machine, or a pulp drying machine.

[0003] Patent FI 62575 discloses a mechanical drive device for a paper machine dryer cylinder assembly, comprising a number of gears that together form a gear transmission. The shaft driven by the drive motor sets the first gear in rotation, which in turn drives a second gear mounted on the cylinder shaft, either directly or via auxiliary gears. The gears of the gear transmission are arranged in a housing located laterally on the dryer section. Both the gear shafts and the shaft of the driven cylinder are mounted on this same housing. Such a solution, in which the drive housing forms the machine frame on which the cylinder and gears are mounted, is referred to as a drive housing.

[0004] Patent FI 98474 discloses a cylinder group drive transmission comprising a box frame to which the rotary drive is transmitted from outside the transmission via a shaft. Rotation of the shaft directly or indirectly drives a toothed edge and subsequently two meshing gears, which transmit the drive to both sides of the transmission and further to the cylinders. The box frame of the transmission is stationary and supported on the foundation, so that the load caused by the weight of the transmission is absorbed by the foundation via the box frame. The drive of two cylinders is achieved by means of a floating coupling between the cylinder shafts and the transmission, which allows for certain angular variations of the cylinder shafts. This prevents bending / twisting caused by misalignment of the shafts from being transmitted from the cylinders to the transmission or vice versa.The cylinder shafts are separately supported on bearing blocks that sit on the foundation.

[0005] Patent FI 115980 discloses a drive device for a paper machine cylinder, comprising a box frame, bearings arranged on the box frame and its bearing cap for rotatably supporting the cylinder via its shaft, and a single- or multi-stage gearbox attached to the box frame. The main gear, which drives the shaft and is arranged concentrically to it, is rotatably mounted on the box frame. A gear coupling is arranged between the shaft and the main gear to eliminate angular misalignment with the main gear. The gear coupling has an externally toothed part fixed to the shaft. The main gear, including its bearing, is attached to the bearing cap of the box frame. Such a compact drive is referred to as a DRG gearbox.

[0006] Today, the drive housings and DRG gearboxes described above, in which the means for supporting the cylinder or roller shaft and the means for rotating the cylinder or roller are arranged on the same box frame, are among the most common drives in the dryer section. Both of these well-known drives can simultaneously drive one or two dryer cylinders or rollers belonging to the same group. Within the drive housing, the gears of the gear transmission and the cylinder shafts are mounted on the box frame, which in turn is supported on the foundation. Using the described drive housings in modern, high-speed paper machines is a challenging task because the gear mesh is not always perfectly straight. For high-speed machines, DRG gearboxes have been developed, which represent compact drive gearbox units.The DRG gearbox is connected to the cylinder shaft via a special gear coupling, which enables high production speeds while simultaneously reducing running noise and vibration levels. One of the biggest disadvantages of DRG gearboxes is their high price; they also require a separate frame structure for support.

[0007] In addition to drive housings and DRG gearboxes, shaft-mounted gear units are also used in deflection rollers of the screen drying section. A shaft-mounted gear unit is a gearbox mounted on the shaft of the driven roller, but not attached to the machine frame by bolts or similar fasteners. In a shaft-mounted gear unit, the end of the shaft is inserted into a bore in the gearbox's output shaft, so that the shaft bears the entire weight of the gearbox and absorbs all other external forces acting on it, except for the torque that causes the gearbox to rotate around the shaft. This latter force is absorbed by the torque arm, which forms a fixed anchor point for the gearbox.

[0008] In known drive gear applications relating to suction rollers, the shaft-mounted gearbox and the bearing housing are firmly joined together via their housings, so that seals subjected to stress due to shaft deflection must be used, which must be serviced and replaced from time to time.

[0009] In known solutions, the drive unit is generally positioned at the end of the roller shaft in such a way that the frame supporting the roller is located between the drive unit and the roller. This solution, as such, is not suitable, at least not for cylinders with condensate drainage on both sides and a vertical siphon.

[0010] The steam required to heat the cylinder surface is supplied to the cylinder via a steam supply line, and the condensate produced during steam condensation is drained from the cylinder via a condensate drain line. The vertical siphon pipes require external support. To avoid a significant risk of vibration, the connections for the steam supply and condensate drain lines to the cylinder must be sufficiently rigidly supported. For the same reason, the spans of the steam supply and condensate drain lines should be kept as short as possible. Attaching the steam supply and condensate drain lines to the gearbox is not recommended due to the associated high risk of vibration.For these reasons, among others, and also because vibrations could lead to the destruction of the steam supply and condensate drainage lines in the case of a shaft-mounted gearbox arranged outside the bearing housing according to the state of the art, the skilled person has not even considered using a shaft-mounted gearbox as the drive gearbox for the drying cylinder.

[0011] The purpose of this invention is therefore to create a new, more advantageous drive specifically for drying cylinders with condensate drainage on both sides and vertical siphons.

[0012] The drive according to the invention is characterized by what is described in the characterizing part of claim 1.

[0013] In the drive according to the invention, the drive transmission consists of a shaft-mounted transmission arranged on the cylinder shaft between the cylinder end plate and the frame. The shaft-mounted transmission is supported on the foundation only by a torque arm. Furthermore, the transmission housing and the bearing housing are coupled to each other in a manner that allows for minimal angular changes of the drive transmission relative to the frame.

[0014] Preferably, the gap remaining between the gearbox housing and the bearing housing is sealed with an elastic seal that allows for slight angular changes of the drive gearbox relative to the frame. This seal consists, for example, of a suitably dimensioned O-ring that ensures the necessary clearance.

[0015] The span of the steam supply and condensate drainage lines can be reduced by arranging the gearbox housing and the bearing housing one behind the other without a partition, so that they share a common oil chamber. The position of the cylinder bearing remains essentially unchanged, since the shaft does not lengthen in this arrangement compared to the current configuration.

[0016] In the solution according to the invention, the cylinder is mounted on the frame and supported on the foundation via the frame, and the drive gearbox is supported by the shaft within the lateral alignment of the machine, so that movements of the cylinder relative to the frame have no influence whatsoever on the function of the gearbox. The motor is connected to the gearbox via a driveshaft. The torque arm is intended solely to prevent the gearbox housing from rotating together with the main gear. Thus, the frame and the cylinder have some freedom of movement in response to temperature fluctuations, and their minor changes in position do not affect the function of the gearbox in any way.

[0017] The shaft-mounted gearbox, which is attached to the driven shaft, is technically simple and inexpensive, suitable for high production speeds, and compensates for angular errors resulting from misalignment or foundation settlement, for example. The shaft-mounted gearbox is lighter and smaller than the DRG gearbox and easier to handle, for example, during replacement. The large bearings used in the gearbox are smaller, less expensive, and easier to source than those used in the DRG gearbox. Replacing the cylinder bearings is simple because the bearing housing is now located at the very outer edge of the shaft.

[0018] With the solution according to the invention, the application range of the plug-in gearboxes in the fiber web machine can now also be extended to the drying cylinders, so that a uniform drive concept is achieved for the entire drying section, there is greater freedom in the arrangement of the drive points, and the screen tension can be more easily controlled in the machine direction by means of the flexible arrangement of the plug-in gearboxes. The more uniform screen tension also results in better runnability and running characteristics.

[0019] The invention will now be described in detail with reference to the accompanying drawings, to whose examples the invention is by no means to be narrowly limited. Fig. Figure 1 shows a drying cylinder with a state-of-the-art drive viewed from the side. Fig. Figure 2 shows the drive-side end face of a cylinder with drive according to the invention in an axonometric representation. Fig. Figure 3 shows a section through the drive according to the invention. Fig. 3A shows detail A from Fig. 3 enlarged. Fig. Figure 4 shows an example of the arrangement of conventional drives in a single-sieve drying section. Fig. Figure 5 shows an example of the arrangement of the drives according to the invention in a sieve drying section.

[0020] Fig. Figure 1 shows a schematic representation of a drying cylinder 10 equipped with a conventional DRG gearbox 19 and condensate drainage on both sides via vertical siphons. The cylinder 10 comprises a cylindrical metal shell 11 and two end plates 12a, 12b, each with a hollow shaft. The shafts associated with the two end plates 12a, 12b are supported on the foundation by the frame 16a, 16b and the bearing housing attached to it. The shaft on the drive-side end plate 12a has a connection 14 for the steam supply line, through which heating steam is fed into the interior of the shell 11. Both shafts on the end plates 12a, 12b each have a connection 15a, 15b for the condensate drain line, through which the condensate collected by the siphons is drained from the interior of the cylinder 10.

[0021] On the drive side of the machine is the drive gearbox 19, which transmits the force required to rotate the cylinder 10 from the drive motor (not shown) to the cylinder shaft. The drive gearbox 19 is arranged here, in a manner known from the prior art, at the end of the shaft outside the frame 16a, with the steam supply line 14 and the condensate drain line 15a located behind the drive gearbox 19. The drive gearbox consists of a so-called DRG gearbox, which is attached to the frame and drives the cylinder shaft 10 via a toothed bushing.

[0022] The solution according to Fig. 1 is functional, supported, and vibration-free, but expensive, and a comparable solution is not used anywhere else in the paper machine. Connecting the condensate drain line 15a, which is connected to the siphon, behind the drive gear 19 is not a good solution, as this increases the support distance from the siphon. This could cause vibrations and oscillations to impair the siphon's function or, at higher production speeds, even destroy it. Consequently, heat transfer through the cylinder jacket 11 and thus the drying performance of the cylinder 10 could be impaired.

[0023] Fig. Figure 2 shows an axonometric view of a portion of a drying cylinder 10 equipped with the drive according to the invention. The drive comprises a frame 16, which supports the cylinder shaft on the foundation, and a drive transmission 18, which is arranged between the frame 16 and the end plate 12 of the cylinder 10. The drive transmission 18 consists of a shaft-mounted transmission supported by the cylinder shaft 10. The shaft-mounted transmission is connected to the foundation by a torque support (not shown) in a manner known per se. A drive pin 21 protrudes from the transmission housing of the drive transmission 18 and can be engaged with the drive motor (not shown). The frame 16 has a mounting ring 22 to which the steam supply line 14 for introducing steam into the cylinder 10 and the condensate drain line 15 for draining condensate from the cylinder can be connected.

[0024] Fig. Figure 3 contains a more detailed illustration of the drive according to the invention. The hollow shaft 13 is supported on the foundation via the frame 16, and the bearing housing 23 and the support bearings 17 are arranged on this frame 16. The shaft 13 can be attached to the Fig. The cylindrical end plate 12 shown in Figure 2 is fastened to the shaft 13 by means of fastening screws 24 through the extension 25. The drive gear 18 comprises a main gear 26 and a drive gear 28, both of which are arranged inside the gear housing 20. The main gear 26 is mounted on the shaft 13 and clamped between the extension 25 and the bearing housing 23. The main gear 26 is enclosed by the gear housing 20, against which the main gear 26 is supported by the bearings 27. Above the main gear 26, a portion of the gear 28 coupled to the drive journal 21, through which the driving force is transmitted to the main gear 26 and the shaft 13, can be seen. Behind the bearing housing 23 is the fastening... gungsring 22 is attached, to which the steam supply line 14 and the condensate drain line 15 are connected, which are in Fig. 2 shown, can be connected.

[0025] Fig. 3A shows a magnification of detail A in Fig. Figure 3, from which the mutual coupling of the gearbox housing 20 and the bearing housing 23 can be seen in more detail. The gearbox housing 20 and the bearing housing 23 are not rigidly attached to one another. They are arranged one behind the other on the shaft, and their non-rotating connection is sealed by an O-ring 29. A small gap remains between the opposing surfaces of the gearbox housing 20 and the bearing housing 23, which allows for small angular changes of the gearbox housing 20 and the gear 26 mounted on it relative to the frame 16. The cylinder-side edge of the gearbox housing 20 is sealed against the shaft 13 by a first labyrinth seal 34, and the edge of the bearing housing 23 facing away from the cylinder is sealed against the shaft 13 by a second labyrinth seal 35. In this way, the amount of sealant required for sealing between rotating and non-rotating parts is halved compared to separate housings.The labyrinth seal is an advantageous and maintenance-free solution for sealing the rotating shaft 13 and the non-rotating body 23, 27 against each other.

[0026] To save space, the gearbox housing 20 and the bearing housing 23 are joined together without a partition, so that the oil chambers of the gearbox housing 20 and the bearing housing 23 are connected to each other. This results in a very compact design that allows the bearings 27, 17 located in the gearbox housing 20 and the bearing housing 23 to be circulated using the same bearing oil. This reduces the need for lubrication lines, and this combined housing also has fewer potential leaks to the outside.

[0027] The assembly formed by the gearbox housing 20 and the bearing housing 23, or the frame 16, is at least as short as the corresponding length of known drive gearboxes. This means that the length of the steam supply and condensate drain lines running through the shaft 13 does not need to be increased. This reduces the risk of vibration in the steam supply and condensate drain lines, resulting in increased cylinder reliability. The mounting ring 22 for the steam supply and condensate drain lines is located directly on the machine frame 16, which also contributes to vibration reduction.

[0028] Since the mutual coupling between drive gear 18 and bearing housing 23 is designed to be flexible, movements of the cylinder 10 relative to the frame 16 have no influence on the function of the gear drive 26, 28.

[0029] Fig. Figure 4 schematically shows a state-of-the-art single-screen drying unit in which the drying cylinders 10 are arranged in the upper row and the deflection rollers 30 in the lower row. The serpentine line 36 shows the path of the drying screen and the fiber web through the drying unit, with the fiber web bearing against the cylinder surface of each cylinder 10 and the screen bearing against the deflection roller surface of each deflection roller 30. The drying unit has a DRG gearbox 31 that drives the last two cylinders 10 in the web direction and a shaft-mounted gearbox 32 that drives one of the deflection rollers 30.

[0030] Fig.Figure 5 shows a drying unit of corresponding size, in which the last drying cylinder 10 of the unit has a drive 33 according to the invention and two of the deflection rollers 30 in the lower row each have a mounting gearbox 32. The mounting gearboxes to be used for the cylinder 10 and for the deflection roller 30 differ from each other in their construction and dimensions, but the same bearings can be used in them and their frames can be manufactured using the same casting pattern.

[0031] The solution according to the invention offers the possibility of forming cylinder groups in which the cylinders rotate at different speeds, which in turn can influence the screen tension.

[0032] Within the scope of protection defined in the following patent claims, numerous different variants of the invention are possible.

Claims

[1] Drive for a drying cylinder (10) of a fiber web machine, which - a frame (16) with a bearing housing (23) which serves to support the cylinder (10) via its shaft (13) on a foundation, - a drive transmission (18) serving to transmit a drive force required for rotating the cylinder (10) to the cylinder shaft (13), which has a gear transmission (26, 28) and a transmission housing (20) in which the gear transmission (26, 28) is mounted, and - means (22) arranged on the frame (16) for attaching a steam supply and / or condensate drain line (14, 15) to the bearing housing (23) supporting the cylinder (10), characterized by , that - the drive transmission (18) consists of a shaft-mounted transmission arranged on the cylinder shaft (13) between a face disk (12) of the cylinder (10) and the frame (16), wherein the drive transmission (18) is supported on the foundation only by a moment support, and - the gearbox housing (20) and the bearing housing (23) are coupled to each other in a way that allows small angular changes of the drive gearbox (18) to the frame (16). [2] Drive according to claim 1, characterized by , that a gap remaining between gearbox housing (20) and bearing housing (23) is sealed with an elastic seal (29) which allows slight angular changes of the drive gearbox (18) to the frame (16). [3] Drive according to claim 1 or 2, characterized by , that there is no partition between the gearbox housing (20) and the bearing housing (23), so that their oil chambers are in contact with each other. [4] Drive according to claim 3, characterized by , that the gearbox housing (20) and the bearing housing (23) are sealed against the cylinder shaft (13) by labyrinth seals (34, 35) and against each other by an O-ring (29).

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