FI98319B - A controllable deflection roller and a method for controlling the load of a controllable deflection roller - Google Patents

Description

98319

Deflection-adjustable roll and method for adjusting the load on a deflection-adjustable roll

In the case of the Ministry of Economic Affairs and the Ministry of Economic Development 5

The invention relates to a method for controlling the load of a deflection-adjustable roll, which roll comprises a stationary roll axis around which a roll shell 10 is rotatably traced and on which a nip is formed with a counter roll, the deflection of the roll shell and / or the nip line load being adjusted on the roll shaft. with load elements which are loaded towards the inner surface of the roll shell by means of a pressure-adjustable pressure oil supplied to the load elements.

15

The invention also relates to a deflection-adjustable roll for forming a nip with a counter-roll, the deflection-adjustable roll comprising a stationary roll axis rotatably tracked around a roll shell, the roll shell and the roll axis being arranged to act on the inner surface of the roll shell and supported on the roll axis. hydraulic loading elements loaded with hydraulic pressure medium, to which »* · ·: the pressure of the supplied pressure medium must be adjusted to adjust the line load of the nip ·: * ·:.

V · • · · • · · • ·· · • · · V: A number of different deflection-adjustable rollers for paper machines or paper finishing machines are already known, which are referred to by various names, such as deflection-compensated roll, zone-adjustable roll and the like. These rolls generally comprise: V a solid or tubular, stationary roll axis and a roll shell rotated around it * · · '** *. Between said shaft axis and the jacket, sliding arrangements acting on the inner surface of the jacket and / or a pressure fluid chamber or chamber baffle 30 are arranged so that the axial profile of the roller jacket can be adjusted or adjusted at the nip • ...... ...

as desired. In particular, the present invention relates to such a deflection adjuster.

in which the axial profile of the roll shell is adjusted by means of sliding shoe arrangements acting on the inner surface of the roll shell 2 98319, which sliding shoe arrangements are loaded against the inner surface of the roll shell by means of a hydraulic pressure medium.

There are certain problems with low line loads driven by hydraulically loaded 5 deflection adjustable rollers. They are due to the temperature control of the roll and the need to lubricate the hydraulic load elements. When loading the roller casing with hydraulic load elements, part of the hydraulic pressure oil used for loading is routed in the normal way through the capillary bores tracked into the load shoes of the load elements to pockets formed on the outer surface of the load shoes. When the roll is driven with very small line loads, the consequence is that the amount of oil flowing through the load elements between the load shoes and the inner surface of the roll shell is very small, whereby the lubrication of the load shoes is endangered. Furthermore, these small amounts of oil flowing through the load elements 15 cause problems with the heating of the roll. In particular, obtaining a uniform cross-machine temperature profile generally requires quite large amounts of oil, so that these oil flows have a cooling effect in addition to lubrication. In the current low line loads • *: a separate oil supply from the compressed oil system of the hydraulic load elements has had to be used to ensure lubrication and to achieve a cooling effect.

• · · • · ··· ® • · ·

In prior art roller solutions, the amount of oil going to the load shoes of the rollers has not been reliably * ·· kept constant. This application prevents new hardware. 25 construction in which the amount of oil going to the load shoe can be kept constant • · * ‘..f regardless of the load pressure. This application also discloses a method by which the amount of oil going to the load shoe can be adjusted.

• · ·· «« »

In the solution according to the application, a load in the direction opposite to the load direction of the load elements is applied to the hydraulic load elements in the direction opposite to the load direction. In this case, the level of the load pressure can be raised to the level required by the desired line load and the opposite force exerted on the load elements by 3 98319. In the invention, it is realized to form a load shoe so that the common effective area A j of the hydraulic oil pockets of the shoe is equal to the area A2 inside the load shoe, which is acted upon by the load pressure P2 to lift the shoe. With said 5 insights, the amount of lubrication going into the oil pocket of the load shoe is always kept constant. The pressure difference (P2 - Pj) between the load pressure P2 and the pressure Pt acting in the shoe pocket is constant when the total effective area A} of the hydraulic pocket (s) is equal to the inner area A2 of the shoe and the back pressure P3 caused by the shoe is constant. Then said pressure difference P2 - P · = P3 · A3 / Aj. If it is desired to change the 10 hydraulic oil flows through the shoe, adjust the back pressure P3. The main condition for this adjustment is that the effective area A} between the shoe and the sheath, i.e. the total effective area of the hydraulic oil pockets in the shoe, is equal to the area A2 inside the shoe, which is acted upon by the load pressure P2 to lift the shoe Ha.

The invention is mainly characterized by what is stated in the claims.

The invention achieves significant advantages over the prior art, and of these advantages, e.g. following. In the method and roll according to the invention, a force acting in the opposite direction to the pressing direction is applied to the hydraulic loading elements, whereby the pressure of the pressure oil used for pressurizing the hydraulic loading elements can be considered to be substantially higher than without the above-mentioned force. The oil flow through the hydraulic loading elements is made state in each loading element or zone formed by the loading elements, whereby the problems previously encountered with respect to temperature are completely avoided. The amount of oil s ·: consumed by the roll is thus made state and higher than in the previously known rollers driven with small: :: \ line loads, as a result of which the roll is made more even: and lubrication of the hydraulic load shoes is ensured.

Fig. 1 shows in a completely schematic vertical section in the machine direction a deflection-adjustable roll according to the invention, which forms a nip with a counter roll.

· * · I 4 98319

Fig. 2 schematically shows, in cross-sectional vertical section of the machine, a deflection-adjustable roll according to the invention and a newly roll forming a nip with it.

Figure 3 is a schematic and partial vertical section of a load element according to a preferred embodiment of a flexurally adjustable roll according to the invention.

Fig. 4 is a schematic view from the direction of the roll shell of a loading shoe of a hydraulic loading element.

10

The graphs of Figures 5a-5f relate to a zone roll with eight zones.

Sub-figure 5a shows a situation where the loading pressures are between 10 bar and 70 bar and the representation illustrates a solution of the prior art.

15

Figure 5b shows the oil flow distribution in each zone according to the situation of Figure 5a. Fig. 5c shows an implementation according to the invention, with a load according to Fig. 5a, in which a constant flow is implemented in each zone.

• \: V 20

Figure 5d shows the modified load condition.

Fig. 5e shows a prior art zone flow distribution and ... 25 »· · * ..! Fig. 5f shows a uniform zone flow distribution according to the invention with said load pressure distribution, corresponding to the same flow distribution as shown in Fig. 5c.

9 • · ·. * ·: 30 In Figures 1 and 2, the deflection-adjustable roll according to the invention is generally indicated by the reference number 9 in the embodiment 1. In the embodiment of these figures, the deflection-adjustable roll 1 98319 comprises a solid roll shaft 3 and a roll shell 2 rotated thereon. Hydraulic load elements acting on the inner surface 4 of the roll shell, the direction of action of which is parallel to the nip plane, are arranged between the roll shell 2. In the embodiment of Figures 1 and 2, neither the end bearing of the roll shell 2 nor the other accessories of the roll 1 are shown, as they are not substantially related to the invention and thus do not form part of the invention. The shaft 3 of the deflection-controlled roller 1 is supported in the conventional manner by means of articulated bearings S on the machine frame. The deflection-adjustable roller 1 forms a nip N with a counter-roller 6, which counter-roller 6 is also mounted on its machine body 7 by means of bearings 8 in a manner known per se by means of bearings 8.

10

In the embodiment shown in Fig. 2, the deflection-adjustable roll 1 is divided in the transverse direction of the machine into zones Ζ ^, Ζ ^, Ζ ^, Ζ ^ so that the hydraulic load elements 10 belonging to each zone ZrZ4 are adjusted in zones. Roll 1 is thus, in the embodiment of the figure, a zone-adjustable roll. The roll of embodiment 15 is divided into four zones, but it is to be understood that the number of zones may be different. Furthermore, in the embodiment of Fig. 2, it is shown that each zone comprises two hydraulic loading elements 10, but it is of course clear that the hydraulic load elements belonging to each zone Zt-Z4. the number of load elements 10 may differ from that shown in Fig. 2. With reference number \ ·. t 20 9 is shown in Figures 1 and 2 for the pressure oil channels leading to the zones Zj-Z4, and the reference number 9 * denotes the oil channel, i.e. the so-called a back pressure channel, the meaning of which will become more detailed in connection with the description of Figures 3 and 4 of the drawing.

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Fig. 3 shows a preferred embodiment of a hydraulic loading element for a flexurally adjustable roll according to the invention, which in Fig. • · ·: f <f 3 is denoted by reference numeral 10a. The axis of the deflection controlled roll is shown in Fig. 3 • · »• · · '. denoted by reference numeral 3, the roll shell by reference number 2 and the inner surface of the roll shell by reference number 4. The hydraulic loading element 10a comprises a load shoe 11a which is loaded against the inner surface 4 of the roll shell 4 in a known manner. pockets 12a formed on the facing surface into which oil is guided through the loading shoe 11a through capillary bores 13a to lubricate the load shoe 11a 6 98319 so that there is always an oil film between said loading shoe 11a and the inner surface 4 of the roll shell. The oil pressure in the pockets 12a is denoted by P 1 and the pressure P, the effective area of action is denoted by A 1. Fig. 4 shows in more detail, for example, the pocket structure of the load shoe 11 according to Fig. 3. The load shoe 5 is denoted by reference numeral 11 in Fig. 4. The pockets 12a of the load shoe 11 thus comprise recesses 12 formed in the curved surface of the load shoe 11 facing the roll shell, bounded by longitudinal and transverse edge bases 12 * and middle bases 12 ', respectively. Of course, the shape of the load shoe 11 can also be different. Oil is introduced into the recesses of the load shoe 11, i.e. the pockets 12, through the bores 13 of the capillary 10 so that the pockets 12 form a hydrostatic bearing from the load shoe 11, whereby there is an oil mattress or oil film between the load shoe 11 and the roll shell.

A recess 14a corresponding to the shape of the outer surface of the load shoe 11a is formed in the roller shaft 3 for each hydraulic loading element 10a. However, said recess or cavity 14a has dimensions larger than the dimensions of the load shoe 1a, so that a clearance remains between the outer surface of the load shoe 1a and the walls of the recess or cavity 14a. In the embodiment of Fig. 3, the load shoe Ha 1 is formed elongated so that said load shoe 11a protrudes deep into the recess formed in the roll shaft 3, i.e. the cavity 14a. A cylindrical cavity 24a is formed in the axial direction of the load shoe of the load shoe 11a.

• ·: The surface area of action of the load pressure P2 i V bounded by the cavity 24a of the load shoe 11a is denoted by Ay. A counterpiece 17a fitted to this cavity 24a of the load shoe 11a is fixed to the bottom of the recess or cavity 14a formed in the roll shaft 3 25 by a screw thread 18a so that the counterpiece 17a is immobile relative to the shaft 3 of the roll. Through the bottom of the screw thread 18a, a connection opens to the compressed oil channel 9. The counterpiece 17a is provided with a flange 19a which is sealed to the wall of the cavity 24a by means of a seal 20a. An inwardly directed flange member 15a is rigidly attached to the lower end of the loading shoe 11a by a suitable connection, such as a threaded connection 16a or the like, which is sealed to the mating piece 17a by means of a seal 21a.

* / ·: The annular surface area of the back pressure P3 is marked with A3. The flange 19a of the mating piece 7 98319 and the flange member 15a in the load shoe 11a thus delimit each other around the mating piece 17a, inside the cavity space 24a, an annular pressure flange 22a. Centrally formed in the counterpiece 17a is a through-pressure oil passage 23a which thus communicates with a pressurized oil passage 9 formed on the roll shaft 3. An axial counter-pressure passage 9 * is further formed on the roll shaft 3. , which communicates with the counter-body 17a through an axial channel 25a and a transverse channel 26a to an annular pressure space 22a.

10

The operation of the deflection-controlled roller 1 provided with the hydraulic loading elements 10a according to Fig. 3, e.g. according to Figs. 1 and 2, is in principle as follows. First, it is clear that each of the hydraulic loading elements of the deflection-adjusted roll 1 according to Fig. 2 is as shown in Fig. 3. As the deflection-controlled roll 1 15 rotates, the nip N formed by said roll 1 and the counter roll 6 is loaded by means of hydraulic loading elements 10,10a by passing compressed oil through the pressure oil channels 9 to each hydraulic loading element 10,10a. The pressurized oil thus passes from the pressurized oil channel 9 formed in the roll shaft 3 to the counterpart 17a formed through the pressurized oil channel 23a to the 20 hollow space 24a formed in the load shoe 11a.

• · · · «·» ·· · J ·

In addition to t 9 * ** *, oil at a constant pressure is preferably fed to the roller shaft 3 via the axial back pressure channel 9 * to the annular pressure space between the counter piece 17a and the load shoe 11a via the connecting channel 9 ”and the counterpiece ... 25a. the pressurized oil supplied to the annular pressure space 22a causes a force in the opposite direction to the load force of the load shoe 1a, which tends to pull the load shoe 1a away from the inner surface 4 of the roll shell 4. As can be seen from Fig. 2, each deflected:. 'ί 30 of the hydraulic load elements 10,10a of the roll 1 are connected to the same and common * · "back pressure channel 9 *, whereby a back pressure is supplied to each load element 8 98319 10,10a in the same amount, each load shoe 11a being subjected to the same force as the opposite load element , 10a .....; ·. ..;. .. ......... .....

in the direction of loading. Due to this counterforce or back pressure, the pressure of the pressurized oil supplied to the cavity 24a must be increased by an amount corresponding to a nip pressure of the desired magnitude in the nip N5.

The effective area A 1 of the pocket of the load shoe 11a is equal to the internal action area A2 of the load pressure P2 and when the back pressure P3 is constant, a situation is reached in which a constant oil flow 10 passes through each hydraulic load element 10a. 1 is obtained completely uniform in the transverse direction of the machine.

In order to keep the amount of oil passing through the shoe at a constant value according to the invention, the effective area Aj between the shoe and the sheath must be equal to the area A2 inside the shoe, which is acted upon by the load pressure P2 to lift the load shoe 11a. The pressure difference P2 - P, can be formed from the force balance equation (1).

Power balance: • · *. ·. ’* 20 • s · *::. *. P2 Aj - P% · Al - Pj * 4j »0« V „A, B ^ Ay l *: - Λ -i - P, = P, -

• * 2 A 1 3 A

· ". Λ1 Λ1 • · Ay A, -''.- A-iid-Tl-ir i1: A, 1 (1> jos A ^ "At - fs -Λ - Pj -J · * (1 - 1) - ft ' P> - Pj Φ. Λι Λι 0 0 .... ·· ϊ · .: • # • * ·

• »I

0 0 9 98319

The pressure difference across the chokes (P2 - Pj) is not dependent on the load pressure P2 when - * 1 and when the term P3 · - is constant with P3 being constant.

If A2 / Aj * 1, the pressure difference (P2 - Pj) changes as the load pressure P2 changes, ie the volume flow through the chokes also changes.

5 ........

Aj = effective area between the shoe and the sheath, ie the total effective area of the shoe's hydraulic oil pockets

Aj = force transmitted to the inlet pressure between the shoe and the sheath 10 A2 = surface area inside the shoe, ie the area affected by the load pressure P2 lifting the shoe A3 = tire area of the back pressure space, ie the area affected by the back pressure P3 causing a force component 15 to be directed away from the shoe nip.

Pj = pressure between the shoe and the jacket, ie in the hydraulic oil pockets • P2 = load pressure • «· p. P3 = back pressure • · »ri • 20 Additional condition between back pressure and load pressure: ··· · • · * * ·: • · · *" P, Αχ * Py Aj - Py Ay

Ay A * ... p m p J * - p —1

S · i M Mj 3 A

*. Λ, Λ, ···: s: ri- ri-

Condition P -l - P *> 0 .... s 2 Ax Ax s ^ 4 * «··« · P v P £ • * M * M ^ • ^ * 2 »· • · · • # # * • ».....

• * · p% * 1 · 10 98319 (the load pressure P2 must be greater than the product of the back pressure P3 and the areas A3 / A2)

Example 5 A3 / A2 = 0.1 and back pressure P3 = 80 bar => the load pressure must be> 8 bar for the shoe to work.

10 Without additional condition the shoe would move axially by the amount of its clearance, The additional condition indicates the required minimum load pressure.

Thus, the condition for the flow of oil through the shoe to be controlled by a certain load pressure and a certain line load must be substantially equal to the areas A1 and A2. In this case, the flow rate is adjusted by adjusting the back pressure P3. If the flow rate is to be kept constant, the back pressure must also be kept constant.

Figure 4 is a top view of the shoe of Figure 3 the direction of arrow K i direction.

Figures 5a-5f show graphically a constant flow rate implementation according to the prior art and according to the invention on a roll comprising eight zones, each zone having five load shoes.

* · * · • · ··· • · ·.

In Figure 5a, the load pressures are between 10 bar and 70 bar. That load situation ... The corresponding oil flows 25 are shown in Figures 5b and 5c. Figure 5b shows a prior art * · * shoe structure, with the shoe structure having a flow distribution corresponding to the load pressure distribution.

* · ·

In the constant flow construction according to the invention of Fig. 5c, the flow distribution is uniform.

• · * ····

As the load condition is changed (Figure 5d), the flows 30 of the prior art construction become equivalent to the load pressures (Figure 5e). Figure 5f shows a constant flow solution of 11 98319 according to the invention. Comparing Figure Se and Sf, it can be seen that the change in load pressures does not affect the flow rates of the constant flow solution.

If you want to change the volume flow through the constant flow shoe, you can do so by changing the 5 backpressures. In this case, the total oil flow to the roll changes, while the flow distribution remains constant.

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Claims (2)

12,98319