WO2007116128A1

WO2007116128A1 - Method in the moment adjustment of a fibre-web machine reel-up/winder

Info

Publication number: WO2007116128A1
Application number: PCT/FI2007/050185
Authority: WO
Inventors: Marko Jorkama; Jari Paanasalo
Original assignee: Metso Paper Oy
Current assignee: Valmet Technologies Oy
Priority date: 2006-04-11
Filing date: 2007-04-03
Publication date: 2007-10-18
Anticipated expiration: 2008-10-11
Also published as: FI20065230L; FI20065230A0; AT507835B1; DE112007000842T5; AT507835A1; FI118962B

Abstract

The invention relates to a method in the moment adjustment of a reel-up/winder, on which reel-up/winder a fibre web is wound into a web roll by means of one or more winding nips. In the method, winding force is adjusted so that tangential tractions directed at the web roll from at least on winding nip i.e. external peripherical loads affecting the web roll remain set independent of run speed and/or acceleration/deceleration.

Description

Method in the moment adjustment of a fibre-web machine reel-up/winder

5 The invention relates to a method according to the preamble of claim 1.

From- prior art are known reel-ups used in connection with fibre-web machines, such as paper and board machines, a fibre web being manufactured by which fibre-web machines, such as a paper machine/board machine, is wound as a full-

10 width web into machine rolls for further processing. The web is wound around a reeling shaft e.g. a spool iron/roll either by means of surface draw in a winding nip between a reeling drum and a web roll being formed or by utilising a centre drive, whereby also the reeling shaft is provided with a drive. In connection with fibre-web machines, such as paper and board machines, are also used unwinders

15 by means of which the web roll wound by the reel-up is unwound in a later stage of treatment for further processing of the fibre web.

From prior art are known carrier-roll winders and multistation winders used in connection with the slitter-winders of fibre-web machines. On a slitter-winder, a

20 full-width web is cut to narrower partial webs and, on the carrier-roll slitter- winders and multistation winders, web rolls, so-called customer rolls, are formed of the partial webs. The winder of carrier-roll slitter-winders comprises carrier rolls supported by two carrier rolls of which the web is wound into a web roll through a nip between one carrier roll and the fibre-web roll being formed. Also a

25 belt arrangement, a so-called set of belt rolls, located around two leading rolls can be used as the carrier roll. In winding, also centre winding can be used in which the web roll being formed is supported from its centre and the fibre web is wound into the web roll through a nip between a winding roll and the web roll being formed. In connection with both carrier-roll winders and multistation winders, a

30 pressure roll can also be used in forming the roll with which roll the web roll be- ing formed is pressed and by means of which surface draw can be caused to the web roll.

As known from prior art, as a basis for the moment adjustment of carrier-roll slit- 5 ter-winders and multistation winders has been used the fact that the terms created by the inertia and the winding resistance of a set (customer rolls on the winder) are distributed equally on the carrier-roll slitter-winders between a rear carrier roll (on which the web comes first) and a front carrier roll or on the multistation winders between a winding roll and a pressure roll. In arrangements known from prior

10 art, winding force (winding force means in an ideal situation (i.e. when there are no losses or inertia forces in the situation) the sum of peripherical forces which rotate the web roll excluding the peripherical forces of its nip which the incoming web touches first) is empirically set as a function of the diameter of a web roll being formed. In connection with winding, especially in deceleration and accel-

15 eration stages related to the set change, additional and reduction terms are also empirically set in the moment adjustment of the winder by which terms one tries to correct the change in the structure of the web roll being created caused by a change in run speed.

20 A problem in the above-mentioned adjusting strategy is that it is not as such based on any winding-technical argument but it is an arbitrary, purely empirically defined strategy. Because of this, the structure of the web rolls has especially changed in connection with decelerations and accelerations and in situations in which the run speed has been considerably changed for some other reason. The

25 change in the structure of the web roll is caused especially by the fact that in these situations in which the run speed is changed, tangential tractions affecting the roll change. Traction refers in this specification to a stress distribution formed in a contact which is caused by external loads/stresses directed at the web roll. Tangential surface tractions are, again, external peripherical loads affecting the web

30 roll being formed through nips. When in connection with adjusting strategies known from prior art one tries to correct the winding force according to accelera- tion and deceleration by additional and/or reduction terms, at the most such an adjusting strategy is provided which functions on the paper or board grade being wound in the situation in question and with acceleration, deceleration and run speed in question. Thus, the moment adjustment strategies of reel-ups/winders, 5 carrier-roll slitter-winders and multistation winders have been incomplete and can have caused web rolls of uneven structure.

The object of the invention is to create a method in the moment adjustment of a reel-up/winder, carrier-roll winder/multistation winder in which the above- 10 described problems and disadvantages of arrangements known from prior art have been eliminated or at least minimised.

A special object of the invention is to provide the moment adjustment of a reel- up/winder, especially winding-force adjustment, which keeps the magnitude of 15 surface tractions affecting the web roll independent of speed changes and inertia terms created by acceleration and deceleration.

To achieve the above-mentioned objects and those which come out later, a method according to the invention is mainly characterised by what is presented in 20 the characterising part of claim 1.

According to the invention is provided the moment adjustment of a reel- up/winder, especially winding-force adjustment, in which the magnitude of surface tractions affecting the web roll is independent of speed changes and inertia

25 terms created by acceleration and deceleration. In the moment adjustment according to the invention, winding force is used as one winding parameter and the winding force is adjusted so that in the most important nips from the viewpoint of the web roll structure, most suitably on carrier-roll slitter-winders primarily the nip between the rear carrier roll and the web roll and secondarily the nip between

30 the front carrier roll or the pressure roll and the web roll and on multistation winders primarily the nip between the winding drum or roll and the web roll and secondarily the nip between the pressure roll and the web roll, the tangential tractions directed at the web roll remain as the set winding force irrespective of run speed or its derivative.

5 According to the object of the invention, because different external peripherical loads are directed at the web roll from different nip rolls, one tries to keep the loads in question in control without the speed changes which occur during winding from affecting the structure of the web roll being formed. Calculated moments according to advantageous embodiments of the invention constitute instructions 10 for use on which different factors should be included in the adjusting strategy for achieving the desired structure of the web roll by adjusting the winding force.

In this specification, rotational resistance refers to a requirement for additional moment caused by bearing frictions etc. Winding resistance i.e. rolling resistance

15 refers to resistance moments created in nip contacts. Winding resistances are zero when the slitter-winder is run without paper. The rotational resistance of the web roll is created by rotation frictions of sockets or core locks. Rotational resistance does not occur on steel-surfaced rolls but it occurs on sets of belt rolls and soft- surfaced rolls.

20

The invention will now be described in more detail with reference to the figures of the accompanying drawing, to the details of which the invention is, however, by no means intended to be narrowly confined.

25 Fig. 1 schematically shows a carrier roll winder.

Fig. 2 schematically shows a multistation winder.

Fig. 3 schematically shows a free-body diagram of the multistation winder. 30

Fig. 4 schematically shows a free-body diagram of the carrier roll winder. Fig. 5 A schematically shows the moment of the carrier-roll winder as a function of diameter in an example.

5 Fig. 5B schematically shows the speed and the winding force of the carrier-roll winder as a function of diameter in an example.

As shown in Fig. 1, a carrier-roll winder comprises two carrier rolls, a rear carrier roll 12 onto which a web W being wound comes first, and a front carrier roll 11

10 supported by which a web roll 10 is wound. The travel direction of the web W is designated with reference SW and the direction of rotation of the rear carrier roll 12 with reference S. By means of a pressure roll 15, nip load is controlled at the beginning of winding and, as the winding proceeds, the primary task of the pressure roll 15 is to keep the web roll 10 in its place supported by the carrier rolls 12,

15 11. On the carrier-roll winder of a slitter- winder, there are typically several web rolls 10 successively in the axial direction of the web roll, and these partial web rolls are called customer rolls, and the web rolls which are simultaneously on the winder are a set.

20 Fig. 2 schematically shows a multistation winder on which the web is wound by means of a winding drum or roll 17 into a web roll 10. The winding core of the web roll 10 can be provided with a centre drive 18 for rotating the web roll 10. Furthermore, the winder shown in the figure comprises a pressure roll 15. The travel direction of the web W is designated with reference SW.

25

In the next description of Figs. 3-4 and equations, the following symbols are used:

Symbol Description Unit

30 F Winding force N/m

F_n Static surface force of pressure roll/width N/m F_pd Static surface force of set of front belt rolls/width N/m

Ji Mass inertia moment of web roll/width Nm/m x s² θι Load angle coordinate of web roll rad

Mi Centre moment of web roll/width Nm/m

5 Mi_μ Rotational resistance moment of web roll/width Nm/m

Q₃ Tangential force between surface-draw roll (pressure roll) and web roll/width N/m

R] Web roll radius m

10 R₂ Radius of winding roll or rear roll m

R₃ Radius of surface-draw roll or pressure roll m

R₄ Radius of first belt roll or front roll m

Q_2rμ Winding resistance force in nip of winding roll or rear roll/width

N/m 15 Qz_rμ Winding resistance force in nip of surface-draw roll or pressure roll/width N/m

Q_4rμ Winding resistance force in nip of belt roll or front roll/width

N/m

W Web tightness prior to winding roll or rear roll N/m

20 J ₂ Mass inertia moment of winding roll or rear roll/width

Nm/m x s2

Θ₂ Load angle coordinate of winding roll or rear roll rad

M₂ Moment of winding roll or rear roll/width Nm/m

M_2μ Rotational resistance moment of winding roll or rear roll/width

25 Nm/m

M_2rμ Rolling resistance moment of winding roll or rear roll (significant only if there is a soft cover on the roll) Nm/m

J₃ Mass inertia moment of surface-draw roll or pressure roll

Nm/m x s2

30 Θ₃ Load angle coordinate of surface-draw roll or pressure roll rad Mz Moment of surface-draw roll or pressure roll/width Nm/m

Miμ Rotational resistance moment of surface-draw roll or rear roll/width

Nm/m

Mi_rμ Rolling resistance moment of surface-draw roll or rear roll/width

5 (significant only if there is a set of belt rolls or a soft-covered roll)

Nm/m

J ₄ Mass inertia moment of front roll or set of belt rolls Nm/m x s2

Θ₄ Load angle coordinate of front roll or first belt roll rad

M₄ Moment of front roll or set of belt rolls/width Nm/m

10 M._4μ Rotational resistance moment of front roll or set of belt rolls/width

Nm/m

M._4rμ Rolling resistance moment of front roll or set of belt rolls/width

(significant only if there is a set of belt rolls or a soft-covered roll)

Nm/m

15 Qi_stat Tangential force of surface-draw roll or pressure roll at standard speed without friction/width N/m μia Winding resistance coefficient in winding-roll or rear-roll nip βR3 Winding resistance in surface-draw-roll or pressure-roll nip μκ4 Winding resistance coefficient in belt-roll or front-roll nip 20 P P ₂₂ Nip load in winding-roll or rear-roll nip ^' N/m

P₃ Nip load in surface-draw-roll or pressure-roll nip N/m

Ps Nip load in belt-roll or front-roll nip N/m

Q⁺, Q, Q Inner force variables of winder N/m

T- Tout Inner force variables of winder N/m

25

Fig. 3 shows a free-body diagram of the multistation winder for the part of essential terms from the viewpoint of rotation equations. The friction and winding resistance terms of the rolls and the web roll are not drawn. In the web roll, there can exist centre moment Mi or surface draw Q₃ (also both can exist at the same 30 time). The rotational equilibrium equation of the web roll is

where Mi_μ is the rotational resistance moment of a winding station and Q_2Ψ and Qsrμ are terms created in the winding-roll and surface-draw-roll nips caused by the 5 winding resistance of the paper roll. For example, according to the description of publication Johnson, K.L., Contact Mechanics. Cambridge University Press, Cambridge, 1985, pp. 306-311, these terms can be expressed as follows in a case in which hysteresis losses are less than 5%:

10 QI^ = VR₂P₂ Q^ = MRiP₃ , (2)

where μ_%2 and μ^ are winding resistance coefficients in winding-roll and surface- draw-roll nips and P ₂ and P ₃, respectively, nip loads in these nips. In equation (2), it would be desirable that the winding resistance coefficients were constants.

15 However, probably they are dependent on at least run speed and possibly a little on winding parameters. Even though equation (2) were not well valid, the sum of winding resistance terms can be evaluated quite accurately, because the other terms of the rotation equations are relatively easily definable. From the equilibrium equation of a web end below the nip, inertia terms can be omitted as void

20 variables. Then, the equilibrium equation is:

T₀₁₁₁ - Q⁺ = Q- + T_1n (3)

Likewise, the equilibrium equation of a web end of a winding-roll wrap can be 25 written without centrifugal and inertia terms:

T_1n - W -Q_w . (4)

The rotational equilibrium equation of the winding roll is 30

where M.2_μ is the rotational resistance of the winding roll and the last rolling- resistance term is only required if the winding roll is a covered roll. The rotational 5 equilibrium equation of the surface-draw roll is

where M$_μ is the rotational resistance of the surface-draw roll and the last rolling- 10 resistance term is only required if the surface-draw roll is covered or belted.

According to the invention, the object of winding-force adjustment is to keep the magnitude of surface tractions affecting the web roll independent of speed changes and inertia terms created by acceleration and deceleration. In this descrip- 15 tion, there is no need to go into actual contact mechanics, because contact- mechanic fitting equations can be assumed independent of inertia terms and net loads directed at the web roll.

Arrange the rotation equation (1) of the web roll so that all surface loads of the 20 web roll related to the winding-roll nip remain on the left-hand side. This yields

If one then wishes that the same surface loads prevailed in the winding-roll nip 25 with all run speeds and at steady speed, deceleration and acceleration, surface draw Oj has to be set as follows:

where F is desired (static) winding force. Respectively, if winding force is obtained with moment Mi, it has to be set as follows:

If one is able to use both surface draw Qs and centre moment Mi, the loads of both the winding-roll and surface-draw-roll nip can be kept independent of the change speed of run speed. Rearrange equation (7) so that also Q₃ is on the left-hand side 10 of the equation:

That is, then also Mi has to be chosen according to equation (9). Furthermore, by 15 arranging the moment equation (6) of the surface-draw roll as follows

it is clear that also Q₃ remains constant if the moment of the surface-draw roll is 20 adjusted as follows

where Q_3stat is surface draw when running at standard run speed and without fric- 25 tion.

Equations (3) and (4) yield

Substituting this result into the moment equation of the winding roll gives

5

This yields according to the invention calculated moments for the multistation winder provided with surface draw: 10

15 This further yields according to the invention calculated moments for the multistation winder provided with centre drive:

20

On the carrier-roll winder, Fig. 4, also the moment and the rotational and rolling resistances of the front roll are included in the rotation equations. Moment M; is considered zero in this consideration. The rotational equilibrium equation of the 25 web roll now becomes

where Q₄ is the tangential traction of the set of front or belt rolls and Q^ is the winding resistance of the paper roll created in this nip. The equilibrium equations (5) and (6) of the winding and pressure roll remain unchanged. As a new equation, 5 consider the rotational equilibrium equation of the set of front or belt rolls

where M₄ is the moment of the set of front or belt rolls, M^ is the rotational resis- 10 tance moment and Mφ-μ is the winding-resistance moment. In the case of the carrier-roll winder, choosing a suitable winding-force strategy is harder, because there are several nips affecting the web roll structure. According to studies reported in the Oklahoma State University publication Web Handling Research Center. Semiannual Technical Review and Industry Advisory Board Meeting, Oc- 15 tober 2000, Tab 2, inter alia, the pressure roll has an important effect on the web roll structure with a small web roll diameter. Evidently, with a larger web roll diameter, the part of the rear roll is determining. Take the rotation equation (19) of the web roll as a starting point and write it so that all surface loads of the web roll related to the rear-roll nip remain on the left-hand side 20

If one wishes that the same surface loads prevailed in the rear-roll nip at all run speeds and at steady speed, deceleration and acceleration, the sum of the surface 25 tractions in the other nips has to be set as follows:

where F is desired static winding force. Because on the left-hand side there is a sum of surface tractions, the implementation of the winding force is not unambiguous.

5 Next, some implementation examples a-c of the invention will be discussed,

a) Setting the surface traction and winding force of a pressure roll

In practice, this is an easily implemented case. Rearrange the rotational equilib- 10 rium equation (6) of the pressure roll

It is clear that if M₃ is chosen so that 15

then surface tractions are

20

above thus F_rr is the static surface traction of the pressure roll.

b) Setting the surface traction and winding force of a front roll or a belt roll

25 Implementing this case requires quite a high output of the pressure-roll motor. Rearranging the terms, the moment equation (20) of the set of front or belt rolls yields

It is clear that if M* is chosen so that

10

then surface tractions are

15 above thus Fμ is the surface traction of the set of front/belt rolls,

c) Driveless pressure roll

This is a common arrangement on e.g. board slitter- winders. Now, surface trac- 20 tions are

This yields according to the invention calculated moments for such a carrier-roll winder in which the surface traction of the pressure roll is set i.e. in implementation example a.

5

10

This yields according to the invention calculated moments for such a carrier-roll winder in which the surface traction of the set of front/belt rolls is set i.e. in implementation example b.

15

20

This yields according to the invention calculated moments for such a carrier-roll winder in which there is no pressure-roll drive i.e. in implementation example c.

25

5 The examples shown in Figs. 5A and 5B are of a carrier-roll winder in which the surface traction and the winding force of the pressure roll are set based on equations (30)-(32), where winding force F=500 N/m, web tightness W=300 N/m, surface force of pressure roll F,_τ=100 N/m, run speed v=40 m/s, acceleration a=\ m/s², density 1,000 kg/m³, web thickness 0.1 mm. Thin lines shown in Figs. 5 A

10 and 5B describe a current type of control where surface force F_n-O. With the current type of moment control i.e. implemented without the method according to the invention, winding force is too small in accelerations and too large in decelerations. The most considerable error effect without the method according to the invention occurs with a large web roll diameter, whereby the inertia of the set is

15 great. Especially in the finish decelerations, control without the method according to the invention can easily produce too hard a surface of the web roll.

The invention was described above only referring to some of its advantageous embodiments, to the details of which the invention is, however, by no means in- 20 tended to be narrowly confined.

Claims

1. A method in the moment adjustment of a reel-up/winder, on which reel- up/winder a fibre web is wound into a web roll by means of one or more

5 winding nips, characterised in that, in the method, winding force is adjusted so that tangential tractions directed at the web roll from at least one winding nip, i.e. external peripherical loads affecting the web roll from at least one winding nip, remain set independent of run speed and/or acceleration/deceleration. 10

2. A method according to claim 1, characterised in that, in the method, the winding force is adjusted on a multistation winder.

3. A method according to claim 1 or 2, characterised in that, in the method, 15 a calculated moment is formed for achieving a desired web roll structure by adjusting the winding force for a multistation winder provided with surface draw based on equations

20

4. A method according to any one of claims 1-3, characterised in that, in the method, a calculated moment is formed for achieving a desired web

25 roll structure by adjusting the winding force for a multistation winder provided with centre drive based on equations

5. A method according to claim 1, characterised in that, in the method, the winding force is adjusted on a carrier-roll winder.

5

6. A method according to claim 1 or 5, characterised in that, in the method, a calculated moment is formed for a carrier-roll winder in which the surface traction of a pressure roll is set based on equations

10

15

7. A method according to any one of claims 1, 5 or 6, characterised in that, in the method, a calculated moment is formed for a carrier-roll winder in which the surface traction of a set of front/belt rolls is set based on equations 20

25

8. A method according to any one of claims 1, 5—7, characterised in that, in the method, a calculated moment is formed for a carrier-roll winder in which there is no pressure-roll drive based on equations

5