FI113384B - Paper machine tissue control equipment - Google Patents

Description

5, 113384

Paper machine tissue control equipment Styranordning for en vävnad i en pappersmaskin

The present invention relates to a papermaker's fabric guiding apparatus, comprising a guiding roll in contact with the fabric, one end of which is mounted on the papermaker's body to be displaced to change the axial orientation of the guiding roll.

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Control devices of the kind shown are used in paper and board machines to control the passage of wires, felts, etc. to keep them sideways at the correct position relative to the machine. In known control devices, the other end of the guide roll is generally mounted on a bearing bracket which is movable by actuator such that the longitudinal axis 15 of the roll is displaced from a position perpendicular to the direction of web travel with the other end of the roll mounted on a permanently mounted bearing bracket.

As examples of known control devices, reference is made to FI Patent Publication 77434 and FI Publication 81148, each of which has 20 bellows members on each side of the bearing housing of the guide roller, which transmits to the bearing housing a force for laterally displacing it; on straws. The movement of the end of the guide roll provided by the pivot mechanism is not straight (> <· · · ·), but the path of the roll is curved, which is not desirable at all for tissue guidance.

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Also known are control devices in which the bearing housing supporting the roll head is arranged along slides or rails. The problem with sliding surfaces is, on the one hand, wear and, on the other, high friction, which requires the use of high shear forces.

In addition, most known tissue control devices have problems with high space requirements and attention. ' : no cost-effectiveness.

• · • ·. It is an object of the invention to provide a simple and reliable tissue control apparatus which does not present prior art problems.

To achieve these and later objects, the control apparatus according to the invention is characterized in that the bearing bracket of the movable end of the guide roller is arranged on at least one and preferably two bellows elements filled with pressure medium, which are arranged to carry the weight of the roll, roll head height position substantially constant, and to allow limited lateral movement of the roll head.

Preferably, each bellows member comprises a valve dimensioned to maintain a substantially constant height of the bellows member such that when the height exceeds a certain threshold a pressure medium is removed from the bellows and below a certain threshold a further pressure 10 is applied to the bellows. The change in height of the bellows member, which is the operating limit of the valve, is of the order + 1 mm. Compressed air is typically used as the pressure medium. A fluid such as water or oil is also an issue, providing more stiffness and damping.

As stated above, tissue guiding devices have previously used pressurized fluid-filled bellows members at the end of the roll as transmitting forces. In the invention, it has been realized to use bellows members as roll supporting members which at the same time allow lateral movement of the roll head and keep the distance between the bearing housing and the papermaking machine body substantially constant, whereby the movement of the bearing housing and hence the roll head is linear.

20. Advantageously, the tissue control apparatus of the invention can also be provided with means for measuring the fabric tension, whereby the fabric tension can be measured within the bellows: 1 ·, · by the prevailing pressure. Combining tissue control with tension measurement can: 1 ·. · The tension measurement function excludes the rest of the tissue cycle.

: T: 25::: Advantages of the control apparatus according to the invention are e.g. high reliability and good cost efficiency. There are few moving parts, no worn sliding surfaces and little friction. - "· 1 '· very little machining. No need for precise machining like in the guides. The risk of soiling is low" ... · when the valve is in a pressurized condition. The steering system is compact in structure and:. · 30 is ideal for very small spaces. A separate device for measuring tissue tension is not required.

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In the following, the invention will be described with reference to the figures in the accompanying drawings, in which details, however, are not intended to be narrowly limited.

Figure 1 shows the end of a guide roll equipped with a control apparatus according to the invention in axo-5 view.

Figure 2 illustrates the control apparatus of Figure 1 viewed perpendicular to the end of the roll. Figure 3 is a cross-sectional view of a bell belonging to the control apparatus.

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Figures 4A-4C show three operating positions of the bellows height control valve.

Figures 1 and 2 show fabric guiding devices in which the guide roll 11 is mounted transverse to the running direction L of the fabric 10. The guiding fabric 10 may be, for example, a vii-15 web, a blanket, or other similar moving fabric of a paper or board machine. Roll 11 is mounted at both ends on a paper machine frame. Its movable end 12 is supported on a bearing housing 13 resting on two bellows 14, which at their lower part are fixedly secured to the paper machine frame (not shown) by means of a mounting flange 15. The opposite end of the roll 11, not shown in the figures, is fixedly but pivotally mounted on the body of the paper machine, for example by means of a spherical roller bearing. The 12 movable roller heads are supported * ·:.! the bellows 14 carry the weight of the roll 11 together with the supporting members of the opposite end of the roll.

'·' 10 position of the fabric roller 11 is monitored by a per se known manner by means of the monitoring device (not '* · shown) which provides instructions to the actuator (not shown) of the roller head 12 from one or the • * 25 in either the direction of arrow A. The movement directions. The actuator can be any electro-mechanical, pneumatic or hydraulic actuator known in the art. Since the direction of travel of the web 10 is always perpendicular to the axis of the roll 11, the change in the axial direction of the roll causes the web 10 to be deflected by the roll 11 in the desired direction and. the position of the fabric in the cross-machine direction can be aligned. Due to the flexibility i * 1 · 30 of the beams 14, the bearing housing 13 moves almost smoothly in the direction of force application of the limited distance actuator. Preferably, the guide means are dimensioned such that the offset of the roll end 12 in the direction of travel of the fabric 10 is at most + 50 mm.

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Figure 3 shows in more detail the structure of the bellows 14 supporting the roll head 12. The side walls of the bellows 14 are made of a resilient material which allows the upper bellows wall 14a to move laterally with the lower bellows wall 14b. Inside the bellows 14 is a valve 16 which serves to maintain the height of the bellows 14, i.e. the distance 5 between the lower wall 14b and the upper wall 14a, so that the lateral movement A of the bearing housing 13 on the bellows 14 is linear. The valve 16 comprises a spindle 17 which is loaded by a spring 21 against the upper wall 14a of the bellows 14. Through valve 16, additional pressure fluid may be introduced into, or removed from, the bellows 14 to maintain a substantially constant distance between the top wall 14a and the bottom wall 14b of the bellows. The circumferential surface of the spindle 17 has two annular grooves 22,23 at different heights 10, which at various positions of the spindle 17 connect the interior of the bellows to either the pressure medium source through the pressure medium channel 19 or to the zero pressure through the leakage channel 20.

The inner space of the bellows 14 is further connected via a duct 24 to a pressure gauge 25, by means of which the pressure inside the bellows 14 can be monitored to measure the tension of the fabric 10. The internal pressure of the bellows 14 is proportional to the forces which tend to bring the upper wall 14a and lower wall 14b of the bellows closer together. These forces are, on the one hand, the force exerted by the own weight of the roll 11 and, on the other hand, the force exerted by the web 10 on the roll 11 towards the bellows 14. Thus, it is possible to monitor the tension of the fabric 10 and its changes by measuring the internal pressure 25 of the bellows 14.

At the free end of the spindle 17 is a bearing roller roller 18 which rests against the upper wall i »14a of the bellows and as the upper wall 14a moves sideways to the lower wall 14b, rotates against it with a very low friction. When the bellows 14 is pressurized, the roller roller 18 only touches the upper wall 14a of the bellows lightly but does not actually carry the load. In the event of a malfunction of the pressure medium system, the bellows 14 slowly collapses and the roll end 12 gradually descends completely to the support of the roller roller 18, allowing the roll end 12 to still be moved despite the lack of pressure medium.

- »». The operation of the bellows 14 and the valve 16 will now be described in more detail with reference to Figures 4A-4C, which show three different operating positions of the valve 16. The arrow F illustrates the total load exerted by the weight of the guide roller Ilya on the bearing housing 13 and the tension of the guide fabric 10 on the bellows 14 «* *,. The portions of the pressure range Ia>> »'» 5 113384 material passageway 19a, 19b, 22 and leakage passageway 20a, 20b, 23 which are above normal pressure are shown in each case.

Figure 4A shows a situation in which the load F from the direction of the roll 11 increases for one reason or another, whereby the spindle 17 of the valve 16 is pressed down against the force of the spring 21 and the bellows 14 is compressed. The spindle 17 slides down the slot 22 reaches a point where a connection is the pressure medium channel input side 19a and output side 19b between. In this case, additional pressure medium (pi „) flows into the bellows 14 and the bellows begins to expand. As pressure increases, spindle 17 rises upwardly until pressure medium conduit 19 closes again upon disconnection.

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Figure 4B illustrates a situation in which the load force F is reduced, as a result of which the bellows 14 at constant pressure begins to expand. The spindle 17 moves towards its lower annular groove 23 reaches a point where a connection is a leak channel input side 20a and output side 20b between. Then the pressure inside the bellows 14 begins to decrease (pout) and the bellows 14 is compressed until the leakage channel 20 due to the return movement of the spindle 17 again closes.

Figure 4C shows an equilibrium situation in which both the pressure medium line 19 and the leakage line 20 are closed and the height h of the bellows 14 remains constant.

The valve 16 is dimensioned such that changes in height h of the bellows 14 are very small. :. . Preferably, the height change Ah is at most ± _1 mm. For example, in the equilibrium situation illustrated in Figure 4C, the height h of the bellows 14 is 79 mm, in the spindle 17: 'position of Figure 4A it is 78 mm and in the position of the spindle 17 shown in Figure 4B.

As the load F changes, the above operation of the valve 16 to constant the height h pi of the bellows 14 causes a controlled pressure change within the bellows 14. When the internal pressure of the bellows 14 is measured by means of the measuring device 25 as shown in Fig. 3, information on the tension of the tissue passing through the guide roll and its changes can be easily derived from the measurement results.

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The pressure medium used in the bellows may be gaseous, such as compressed air or liquid such as water or oil. When gas is used as the pressure medium, a vibration damping device, which may be a friction damping device or a viscose damping device of the same type as the vehicle shock absorbers, may be incorporated into the bellows if necessary. When the pressure medium is liquid, no separate silencer is required.

The invention also relates to a device used in connection with a tissue machine of a paper or board machine, which combines the devices necessary for controlling the tissue and the devices for measuring the tension of the tissue.

The invention has been described above with reference only to a preferred embodiment thereof, the details of which are not to be construed as being limited in any way. Many modifications and variations are possible within the scope of the inventive idea defined in the following claims.

Claims (10)

A guide apparatus for a papermaker's fabric (10), comprising a guide roll (11) in contact with the fabric (10), one end (12) of which is movably mounted on the body of the papermaking machine to change the axial orientation of the guide roll (11). (11) the bearing bracket (13) of the movable head (12) is arranged on at least one and preferably two pressurized fluid-filled bellows members (14) arranged to carry the weight of the roll (11) to hold the roll head (12) ) at a substantially constant height and to allow limited lateral movement 10 of the roll head (12). Control device according to claim 1, characterized in that each bellows element (14) comprises a valve (16) dimensioned to maintain the height (h) of the bellows element (14) substantially constant so that when the height exceeds a certain threshold value ( h + Ah), the pressure medium is removed from the bellows and, below a certain threshold (h - Ah), additional pressure medium is introduced into the bellows. Control device according to Claim 2, characterized in that the change in height of the bellows element (14) within the operating limit of the valve (16) is of the order Ah = + 1 mm. 20th Control device according to claim 2, characterized in that the spindle: (17) of the valve (16) is loaded by an elastic loading member (21) on the upper wall of the bellows member (14):; (14a) and the end resting against said upper wall (14a) of the spindle (17) is wide. ' ·: Rolled cylindrical roller (18). * 25 '· 1 Control apparatus according to one of the preceding claims, characterized in that it comprises means (24,25) for measuring the tension of the tissue (10). »· * 1 · ··· 1 Control device according to Claim 5, characterized in that the means for measuring the tension of the fabric comprise a pressure measuring element (25) adapted to measure the pressure within the bellows (14). · 8 113384 Control apparatus according to claim 6, characterized in that the pressure measuring element (25) is connected to the interior of the bellows (14) via a channel (24) in its lower wall (14b). 7, 113384 Control apparatus according to one of the preceding claims, characterized in that it comprises means for damping the vibration of the bellows (14). Control apparatus according to claim 8, characterized in that the means for damping the vibration comprises a viscose dampener. 10 • · · • t 1 · • • • • • • • • • • • • · · · · · · · · · · · · · · · · · 113384