FI116227B - The extended-nip - Google Patents

Description

116227

The extended-nip

The invention relates to a long nip press as set forth in the preamble of the independent claim below.

A typical long nip press comprises a press roll and a counter roll. The press roll typically comprises a rotatable, fluid-impermeable elastic belt sheath, a fixed and preferably non-rotatable support beam extending axially across the belt sheath to support at least one loading shoe supported by the support beam and a concave loading member, against the roller to form, together with the backing roller, a compression zone comprising a plurality of loading units in the axial direction of the press roll, each of which comprises an operably connected piston-cylinder pair.

In typical and known solutions, the individual cylinders touch their upper surface to the shoe beam and directly follow the shoe beam movements.

t I * f (I · * * »*» ·;; · 20 During the operation of the long nip press, the load shoe is mainly subjected to • '; are called frictional forces and are caused by the friction of the belt sheath against the surface of the loading shoe as the belt sheath passes through the compression zone. movement of the load shoe: · ·, and / or turning, the frictional forces on the load shoe must be applied.

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A commonly known solution for applying frictional forces from a load shoe to the body of an elongated pepper clamp is one in which the load shoe is provided with support members on the outboard side against which the load shoe is compressed by frictional forces. For example, FI 89286 discloses a long nip-5 clamp having a support bearing on the outboard side of the loading shoe for receiving frictional forces acting on the loading shoe during use, which support includes a fixed support element connected to the support beam. A disadvantage of the solutions described above is the potential problems caused by the horizontal support of the load shoe for adjusting the load shoe position, possibly reducing the number of load shoe positions. In addition, known solutions such as those described above are often complex in construction, which may result in high construction and maintenance costs. Also, the load uniformity problems have arisen, adhering to the shoe attached to the trailing edge and the front side to get to.

15 In the known solutions, since the cylinders do not touch each other, they also do not support each other and therefore can tilt in the axial direction. Therefore, additional structures are required to support the cylinders, which in turn increases the number of parts in the equipment, increases the weight of the structure and makes the structure more complex.

The purpose of the long nip press according to the present invention is to eliminate or at least reduce the problems arising from the above-mentioned prior art.

It is a further object of the present invention to provide a long nip press,. 25 wherein the frictional forces exerted on the loading shoe are applied to at least one load. agonize over the load nipple to the support beam of the long nip press.

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Yet another object is to provide a long nip press with a load-bearing. ·. : The load units that load the roller are designed so that the expansion of the load shoe • »» 30 does not cause any significant problems with the operation of the load units.

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In order to accomplish, among other things, the aforementioned purposes, the long nip press according to the invention is essentially characterized in what is stated in the characterizing part of the attached independent claim.

5

It is typical for the long nip press of the present invention that the piston of at least one piston-cylinder pair comprises a first end which is inserted within the cylinder and is pivotable relative to the centerline of the cylinder. Further, the piston of the above-mentioned piston-cylinder pair further comprises a second end which is disposed within the piston body and is pivotable with respect to the center line of the piston body. Furthermore, it is typical of the long nip press according to the present invention that the cylinder of the aforementioned piston-cylinder pair is movable between sliding rails arranged in the axial direction of the press roll, thereby loading the belt casing when the piston-cylinder pressurized space is introduced.

In a preferred long nip press according to the present invention, said sliding rails extend substantially uniformly on both sides of a plurality of rows of pistons. Thereby a uniform sliding surface is provided which prevents the cylinder from moving in the longitudinal direction of the machine, but which allows movement of the cylinder in the axial direction of the press, i.e. in the transverse direction of the machine.

In a preferred long nip press according to the present invention, a. . between each pair of piston-cylinders and at least one slide rail, wedge members 25 are provided to prevent displacement of the piston-cylinder pair in the axial direction of the long nip press. Preferably by locking the machine with the longitudinal center line ”··. cylinder (s), thermal expansion during loading shoe operation * can occur in both directions from the center line of the machine without thermal expansion causing problems with the press. The free cylinders 30 can move with the expanding load shoe.

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In a preferred long nip press of the present invention, the loaded loading units, preferably their cylinders, are arranged at least partially in contact with each other. Here the adjacent cylinders support each other and prevent the cylinders from tilting in the axial direction of the press.

The major advantage of the long nip press according to the present invention is its simple but still highly functional design, whereby it can be manufactured at a reasonable manufacturing cost, and its maintenance and servicing is easy and quick. In addition, the present long nip press has a very robust construction.

Further, the long nip press of the present invention has the advantage of having a frictional force applied to its load shoe on the press body, such as a support beam.

Furthermore, the long nip press of the present invention is not susceptible to interference or incorrect loading conditions which could be caused by thermal expansion of the load carrier during use.

The invention will now be described in more detail with reference to the accompanying drawing, in which: •. . is a diagrammatic representation of a cross section of a long nip press »* · ·. ···. 25 ends viewed, • · '. Fig. 2 schematically shows a partial section of a long nip press. · · ·, Viewed from the side, ie the longitudinal direction of the machine, and '. Figure 3 is a sectional view A-A of Figure 2.

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Figures 1 show, by way of example and schematically, the structure of a long nip press viewed from the end of the press, i.e. in the transverse direction of the machine. The long nip press comprises an upper counter roll 1 and a lower press roll 2 forming a compression zone or nip N. The counter roll 1 may be a heated or a non-heated roll. The press roll 2 comprises a belt diaper 3 made of a resilient and liquid impermeable material through which a fixed and non-rotatable support beam 4 passes. In addition, the press roll 2 comprises loading means 5 for loading the belt diaper 3 towards the reel to form the abovementioned nip N -10 sheets of paper or cardboard. The direction of travel of the web to the nip is indicated by an arrow.

The loading means 5 comprises a loading member 6 attached to a support beam 4 and a loading shoe 8 parallel to the axle of the press roll 15 connected to the loading member by a saddle member 7.

• ;: Said wedge 9 transmits a load of frictional force applied to the loading shoe to the saddle member.

The load member 6 comprises a plurality of load units disposed in the axial direction of the press roll 2, one of which is shown in Figure 1. Each load unit comprises a cylinder 12 and a piston 13 which is partially inserted within the cylinder: such that at least the first end 14 of the piston is pressurized by the cylinder. 25 in the detergent mode 15.

The first end 14 of the piston comprises a sealing member 16 which seals the interior of the piston. the gap between the lever surface and the wall of the pressure medium chamber. The first end is patterned; partially rounded, with the piston and cylinder

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They may, if necessary, turn to each other.

The other end 18 of the piston 13 is disposed in the piston body 19 attached to the support beam 4 via a spherical thrust bearing 20. The spherical thrust bearing allows the piston to rotate relative to the piston body.

5

As shown in the figure, the cylinder and piston form a functionally coupled piston-cylinder pair in which a pressure medium, such as hydraulic oil, is passed through a piston-tracked pressure fluid connection 17 to the pressure medium to increase the pressure in the fluid medium space. The means for introducing the pressure medium into the pressure medium connection and the means for pressurizing the pressure medium or controlling its flow are not shown in the figure because they are generally known to the person skilled in the art. As the other end 18 of the piston rests on the housing 19, the cylinder moves away from the piston and thus loads the loading shoe when the pressure medium is introduced into the pressure medium compartment.

On the sides of the cylinder 12 shown in Figure 1, on the inlet and outlet sides of the press, there is a sliding -...: rails 21 which support the cylinder in the longitudinal direction of the machine. The sliding rails are fixed to the support beam by 4 screws. Supported by sliding rails, the cylinder cannot rotate longitudinally of the machine when the cylinder is moved into a fluid medium chamber by means of a pressurized medium. The sliding surface of the cylinder comprises a sliding rail

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a transmission surface 22 disposed against the load shoe and transmits the frictional forces transmitted from the loading shoe to the cylinder through the slide rail to the support beam. In addition to the one shown in the figure. >. According to t, the upper surface of the cylinder is substantially spherical.

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The saddle member 7 is a plate-shaped body, the underside of which is facing the load member ·· *. it has a concave recess which, when the saddle member is connected to the load member, forms a spherical surface of the load member and the size of the saddle member. ·. : a tax recess with a ball-joint, which allows the saddle

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30 rotation of the load shoe relative to the load member. Likewise, the frictional force exerted on the load 7 116227 shoe is transmitted through said spherical surface from the saddle member to the loading member.

The loading shoe 8 shown in Fig. 1 is made of a suitable metal, for example 5, of aluminum. The upper surface of the load shoe, i.e. the face of the counter roll, is concave. The concave surface could further comprise a hydrodynamic pressure pocket. A hydrostatic pressure pocket may also be used as the pressure pocket, wherein the loading shoe would further comprise at least one feed line for supplying cooling and lubricating oil to the pressure balance. When the loading shoe is pressed against the counter roll, the belt sheath settles into a shape defined by the surface of the loading shoe and the counter roll rolled against the press roll, whereby the belt shroud together with the counter roll forms a compression zone through which the paper or board web can be drained.

The long nip press also comprises other parts and members not shown in the figure to clarify the pattern. Such means include, for example, means for supplying coolant and lubricant to the surface of the press shoe, means for supplying pressure medium to the cylinder acting as a loading member, etc. In addition, a long nip press • * ·,. may be implemented in reverse, i.e. with the press roll located above and opposite; i '20 below the roll.

Fig. 2 is a schematic partial cross-sectional view of the long nip press ** · * as viewed in the longitudinal direction of the machine. Figure 3 is a sectional view A-A of Figure 2.

. . Figures 2 and 3 use, where applicable, the reference numeral of Figure 1.

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As shown in Figures 2 and 3, the uniform loading shoe 8 is loaded with nine load members 6, whereby the belt sheath 3 is pressed against the counter roll 1.

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The loading members may also be more or less present in the long nip press; than in the embodiment illustrated in the figures. The number of load elements required * tl • · 8 116227 depends, e.g. the width of the press and how the transverse pressure distribution of the machine is to be controlled.

The cylinders of the tracked load units are partially tracked to be in contact with one another. Here, the adjacent cylinders support each other and prevent the cylinders from tilting in the axial direction of the press.

As shown in Fig. 3, wedges 10 23 are disposed between the central loading unit 6 'on the longitudinal centerline of the machine and the sliding rails 21, whereby said loading unit is also locked against transverse rotation of the machine. In this case, the thermal expansion during loading of the load shoe can occur in both directions from the centerline of the machine without the thermal expansion causing problems with the operation of the press. Free cylinders can move with the expanding load shoe. It is also possible to lock more than one of the load units. In addition, the locking can be accomplished by other means than wedges. One such method is to fabricate at least one of the slide rails having a recess at the lockable load unit. Also-. the deflection of the roller body does not cause any problems with the cylinders since the piston parts can I ·; ·, Turn as needed.

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'20 MM

*: ··· In no way is the invention limited to the embodiment described in the preceding description, but may be varied within the scope of the inventive idea contained in the claims.

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MM

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Claims (4)

A long nip press comprising a press roll (2) and a counter roll (I), the press roll (2) comprising a 5 rotatable, fluid-impermeable elastic belt skirt (3), a fixed and preferably non-rotatable support beam (4) extending axially at the belt skirt. (3) across, - at least one load shoe (8) supported by a support beam (4) having a concave surface portion, and 10. a loading member (6) for loading the load shoe (8), i.e. pressing the concave surface portion against the elastic belt sheath (3) (3) may form, together with the counter roll (1), a compression zone (N) comprising a plurality of loading units (6 ') arranged axially in the axial direction of the press roll (2), each comprising an operably connected piston (13) - 15 cylinder (12) - a pair, wherein the piston (13) of the at least one piston-cylinder pair comprises a first end (14) disposed at least partially on the cylinder in (12) and arranged to be pivotable with respect to the cylinder (12), and respectively the piston (13) of said piston-cylinder pair further comprises a second end (18) disposed in the piston body (19) and arranged in the piston. rotating with respect to the nest, and that ''. 20 - the cylinder (12) of the aforementioned piston-cylinder pair is arranged to move between the slide rails (21) arranged axially in the press roll (2) and thus to load the belt sheath (3) when pressurized between the piston (13) and the cylinder (12) (15) is driven by a pressure medium, characterized in that the load units (6 '), preferably their cylinders (12), arranged in a row, are arranged at least partially os · · * 25 in contact with each other. The long nip press according to claim 1, characterized in that the slide rails (21) extend substantially uniformly on both sides of the row of load units: '(6'). 30 10 116227 Long nip press according to Claim 1 or 2, characterized in that wedge members (23) are disposed between at least one piston-cylinder pair and at least one slide rail (21) to prevent displacement of the piston-cylinder pair in the axial direction of the long nip press. 5 3, 116227 Long nip press according to Claim 3, characterized in that at least one of the five middle piston-cylinder pairs of at least one piston-cylinder pair row, preferably the middle piston-cylinder pair, and at least one sliding rail (21) are provided with piston-cylinder to prevent the pair from shifting in the axial direction of the 10 long nip presses. * t> I * * 116227 //