FI68886B - PRESSURE RELEASE FOR ENCLOSURE ADJUSTMENT AV VALIDATION - Google Patents

Description

68886

Press roll with a device for correcting the deflection of the roll shell

The invention is based on a press roll according to the preamble of claim 1, which is known from Figure 5 of DE-A-22 45 597. Such a press roll can be used, for example, in the press section of a paper machine for drying a paper web. It can also be part of a calender used to calender paper. In addition to this, there are numerous other possible uses.

With the aid of the deflection correction device, the following can be achieved: in the press nip between the press roll and the counter roll, the pressing force can be kept largely constant over the entire working width. However, if necessary, different compressive forces in the areas can also be adjusted.

In order to transfer the compressive forces from the roll shell to the bending beam, several pressure pieces are generally provided. Each such pressure piece has an end surface which is part of the cylinder liner surface. With this end surface, the pressure piece slides against the inner surface of the roll shell. To reduce the frictional forces between the roll shell and the pressure piece, there are hydrostatic pressure pockets on the end face of the pressure piece. It is known from Figure 5 of DE-A-22 45 597 to provide a central pressure pocket and a plurality of additional pockets distributed around the central pressure pocket.

Two such additional pockets are arranged circumferentially adjacent to the central pressure pocket. It is further known that 2 68886 (DE-A-22 30 139, Fig. 3) provide four equal pressure pockets. In this case, the two pressure pockets are opposite each other in the direction of the roller axis and the other two are in the circumferential direction. In other words: the strips between the pressure pockets extend diagonally to the main pockets of the press roll.

By means of these known groupings of hydrostatic pressure pockets, the pressure piece, which must be known to be bendable with respect to the bending beam, can be stabilized against bending relative to the roll shell.

This is a question of stabilization against bending both in the direction of the axis of the roll and in the circumferential direction, i. in a plane perpendicular to the axis of the roll. In other words, care is taken to ensure that the axis of the pressure piece always runs exactly in the radial direction. According to DE-A-22 30 139, the stabilization against bending in a vertical plane with respect to the axis of the roll can be further improved so that the strips, in contrast to Fig. 3, run parallel to the main axes of the roll.

The purpose of these known measures is that the so-called pressure strip edge strip is at all points as evenly as possible from the roll shell, so that the thickness of the lubricant film therein is the same everywhere and thus metal contact between the pressure piece and the roll shell is prevented. However, despite these measures, there is still a risk, under certain circumstances, that such metal contact will occur, at least occasionally, especially when the roll shell is in place or when it is actuated.

The object of the invention is therefore to improve the known 3,6886 press rolls in that, to this extent, metallic contact between the pressure pieces and the roll jacket is avoided with greater certainty in all operating conditions.

The problem is solved by means of the press intelligence set out in claim 1. The solution of the problem is substantially successful thanks to the combination of the following measures:

On the other hand, care is taken to ensure that only one channel is provided for supplying pressure medium to the hydrostatic pressure pockets, which channel ends in the central pressure pocket. This is known per se from Figure 5 of DE-A-22 45 597. In this case, the pressure medium is fed into the additional pockets only from the central pressure pocket, namely via intermediate lists. The additional pockets thus regulate a slightly lower pressure than the central pressure pocket. At the same time, there is a relatively large pressure difference between the central pressure pocket and the pressure space between the bending bar and the pressure piece. Thus, the cross-section of the connecting channel from the pressure space to the central pocket can be relatively large, so that there is no risk of clogging and from this side the operation of the hydrostatic support is guaranteed (thus there is no risk of metal contact).

In order for the additional pockets to receive sufficient pressure from the central pocket despite the absence of their own pressure lines, the protrusions in the central pocket mentioned in feature c) of claim 1 ensure that the length of the inner strips forming the boundary in each additional pocket is relatively large. Thus, a lot of pressure medium can flow into the additional pockets, compared to the amounts of pressure medium that flow out of the additional pockets through the strips on the outside edge of the pressure piece.

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However, another measure must be taken: the above-mentioned projections must be arranged so that they extend in the direction of the main axis of the press roll. Thus, it is possible to arrange additional pockets diagonally to the main axes of the press roll. It has now been found that such an arrangement of additional pockets makes it possible to provide additional stabilization of the pressure pieces relative to the roll shell, namely stabilization of the pressure pieces against rotation about their axis. Namely, as long as the stability measures of the pressure pieces are limited to the axes of the pressure pieces extending in the radial direction, there may still be metallic contact between the pressure piece and the roll shell, namely due to the pressure body rotating about its axis. However, such rotation could also be prevented by mechanical devices.

However, it has been found that this subtask can be solved by the construction method according to the invention with a much simpler input. However, DE-A-2 147 207 (= GB-A-13 59 839) discloses a hydrostatic bearing for a shaft provided with a bearing bracket with four additional diagonally arranged pockets in addition to the central pressure pocket. However, these receive the pressure medium exclusively through the throttling channels, where there is a risk of blockage. The central pressure pocket is also round and therefore has no protrusions.

A good result is obtained when the central pressure pocket has four protrusions. The shape of the central pressure pocket according to claim 2, which has four protrusions, further improves the supply of pressure medium from the central pressure pocket to the additional pockets. The cross-shaped shape of the central pressure pocket in claim 3 facilitates the manufacture of the pressure piece. Preferably, the central pressure pocket can be made by milling.

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Also substantially preferred is the substantially rectangular shape of the end surface of the pressure piece according to claim 4. In this case, however, four additional pockets are arranged at the corners of the pressure piece, where they provide the maximum stabilizing effect against the rotation of the pressure piece at the greatest possible medium distance. It is very advantageous to use the measures set out in claims 3 and 4 together. This ensures that the additional pockets are very large compared to the central pocket and that the inner strips forming the boundary to the central pocket in each additional pocket are substantially as long as the outer strips at the edge of the pressure piece. In other words, the length of the strips through which the pressure medium flows into the additional pocket is substantially equal to the length of the strips through which the pressure medium flows outwards.

By means of another aspect of the invention as claimed in claim 5, a very favorable value is obtained for the pressure drop between the central pressure pocket and the pressure space between the bending beam and the pressure piece.

Embodiments of the invention will now be described in more detail with reference to the drawing, in which Figure 1 shows a schematic cross-sectional view of a press roll, Figure 2 shows a partial longitudinal section along line II-II in Figure 1, Figure 3 shows a view of show images of the sliding surfaces of the pressure pieces modified compared to Fig. 3.

The press roll shown in Figures 1 and 2 comprises a substantially tubular roll shell 1 rotatable about its longitudinal axis and a non-rotatable bending beam 2 extending through the inner part of the roll shell 1. It is not shown in the drawing that the bending beam 2 can be supported at both ends on a fixed machine frame, but it can also be arranged on a movable support device, for example according to patent application P 30 07 112.6. The bearings conventionally arranged at the ends of the roll shell between this and the bending beam are also omitted from the drawing.

In order to transfer the compressive forces from the roll shell 1 to the bending beam 2, several pressure pieces 3 are provided, of which only one is shown in Figures 1 and 2. The pressure piece 3 has its end surface 3a, which is a part of the cylinder shell surface, slidably against the inner surface of the roll shell 1. The bending beam 2 manually extends into the interior of the pressure body 3. A cylindrical pressure space 8 is arranged here, which is rigidly connected to the bending beam 2 via the piston rod 4a. The shape of the piston 4 is chosen so that radially, but it is also bendable.

This takes into account the state that the bending beam bends as it receives the compressive forces. Deviating from this structure, it can also be arranged as follows: the underside of the pressure piece can have a piston-like stop which engages in a cylindrical hole arranged in the bending beam 2.

Through the pressure medium lines 10, the pressure medium is led to the pressure space 8. As a result, the pressure piece 3 is pressed against the roll shell. A hydrostatic pressure pocket 6 is embedded in the sliding surface 3a of the pressure body 3, which receives pressure medium from the pressure space 8 through the hole 5. In addition, four additional hydrostatic pressure pockets 7 are provided. These are not in direct line communication with the pressure space 8.

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Rather, 6 pressures are fed from the central pressure pocket. The pressure medium then flows through the inner pressure strips 11 between the central pressure pocket 6 and the additional pockets 7 to the additional pockets 7.

In this connection, it is important that the central pressure pocket 6 has protrusions 9 (according to Fig. 3) or 19 (according to Fig. 4) or 29 (according to Figs. 5 and 6) extending from the edge strip 12 or respectively. 22 or equivalent Up to 32. The embodiments according to Figures 3-6 are further consistent in that the additional pockets 7 or 17 or equivalent 27 or equivalent 37 is arranged substantially diagonally with respect to the main axes of the sliding surface of the pressure body. One of these main axes is parallel to the axis of rotation of the press roll and the other perpendicular to it.

With the pressure pieces 3 or 4 according to Figs. 13 is a rectangular shape when viewed towards their sliding surface. In this case, the larger side of the rectangle extends parallel to the axis of the press roll. These four additional pockets 7 or equivalent. 17 are arranged at the corners of a rectangle. As a result, the additional pockets are at a relatively large distance from the centerlines of the sliding surface. This enhances the aggravating effect of the additional pockets shown above.

According to Figure 3, the central pressure pocket 6 has the shape of a cross. Correspondingly, the additional pockets are rectangular. This arrangement has the advantage that the strips 11 between the central pocket 6 and the additional pockets 7 are relatively close to the center lines of the sliding surface and that thus, when the pressure piece 3 possibly bends, the maximum possible return moment is generated.

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According to Figure 4, the central pressure pocket 16 has the shape of a diamond. Correspondingly, the additional pockets 17 are triangular.

As shown in Figures 5 and 6, the pressure pieces 23 or 33 is a completely circular shape when viewed towards their sliding surface. Of course, an oval shape may also come into question. In Figure 5, the central pressure pocket 26 has two protruding ground 29 extending in the circumferential direction (relative to the roll shell) up to the edge strip 32. In contrast, the central pressure pocket 36 of the embodiment of Fig. 6 has four such protrusions 29- These all extend, as in Figs. 3 and 4, along the center lines of the sliding surface and thus in the direction of the main axes of the press roll.

Claims (5)

9 68886 A press roll for the pressure treatment of webs of material, in particular paper webs, which roll is provided with a rotatable cylindrical roll roll pressed against a counter roll and a device for correcting roll deflection, comprising a bending beam passed through the roll sheath and supported at its ends. bendable relative to the bending beam and displaceable radially, and further comprising the following features: a) the sliding surface (3a) of the pressure body (3) facing the roll shell (1) has a central hydrostatic pressure pocket (6) and at least four central pressure pockets (6) distributed an additional pocket (7) arranged, the assembly of pockets (6, 7) being surrounded by an edge strip (12), b) only a single channel (5) connecting the bending beam (2) of the central pressure pocket (6) is provided for supplying pressure ) and the pressure piece (3) and a pressure chamber (8) connected to the pressure medium source, c) characterized in that in the central pressure pocket (6; 16; 26; 36) are projecting towards the sliding surface (3a) of the pressure piece, projections (9; 19; 29) arranged in the direction of the main axis of the press roll up to the edge strip (12; 22; 32) and that additional pockets (7; 17; 27; 37) are arranged substantially diagonally to the main axes of the press roll, and that the additional pockets (7; 17; 27; 37) do not have their own pressure supply channels. Press roll according to Claim 1, characterized in that the central pressure pocket (6; 16; 26; 36) has four projections (9; 19? 29), two of which extend in the axial direction and two vertically relative to this in the edge strip (12; 22; 32). ). 10 68886 Press roll according to Claim 2, characterized in that the central pressure pocket (6; 36) has the shape of a cross. Press roll according to Claim 1, 2 or 3, characterized in that the sliding surface of the pressure body (3; 13) has a substantially rectangular shape. Press roll according to one of Claims 1 to 4, characterized in that the pressure surface of the central pressure pocket (6) is approximately 0.7 to 1.5 times the effective pressure surface of the oil pressure space (8) between the bending bar (2) and the pressure piece (3). 68886 11