SE1951554A1 - Dewatering apparatus having an adjustable nip - Google Patents

Abstract

An apparatus (100) for dewatering a fibrous material (2) is disclosed. The apparatus (100) comprises a second roll (41) and a third roll (42) that form a nip in which water is pressable out of the fibrous material (2). Each end (541, 542) of the second roll (41) is mounted in a respective bearing, which is eccentrically located at a respective location (545) in a respective circular collet (54). The respective circular collet (54) is rotatably mounted in a respective circular mounting frame (600). A respective transmission (50) at said each end (541, 542) is arranged to linearly extend or retract a respective beam (520) to rotate the respective circular collet (54) in the respective circular mounting frame (600). A distal end (550) of the respective beam (520) is rotatably connected to the respective circular collet (54) and a proximal end of the respective beam (520) is mounted in the respective transmission (50).

Description

DEWATERING APPARATUS HAVING AN ADJUSTABLE NIP FIELD OF THE INVENTIONThe present invention relates to dewatering of f1brous materials, such as wood chips, saw dust or the like. In particular, an apparatus for dewatering of f1brous material is disclo sed.

BACKGROUND OF THE INVENTION In order to use wood a source of energy, wood chips can be dewatered and subsequently usedas fuel. To remove water from the wood chips, the wood chips may be subjected to heat thatcauses moisture in the wood chips to evaporate. However, such methods are time-consumingand require large amounts of energy which makes such methods less effective in terms ofenergy economy. A method which is more economical in terms of energy economy is todewater the wood chips by means of compression. In an article published 2010 by“ScienceDirect”, Dewatering of high-moisture wood chips by roller compression method(Takahiro Yoshida, Hiroyuki Sasaki, Tsutomu Takano and Osamu Sawabe), a method ofdewatering wood chips by roller compression was disclosed. In that article, a method wasdescribed in which wood chips were compressed between rolls. The article discloses anapparatus with a primary and a secondary unit that both included rollers. The secondary unithad a lower roller with ho les having a diameter of 6 mm that were intended to allowsqueezed-out water into an aspiration fiannel attached inside the roller. The water wasreportedly expelled by an exhaustion fan attached to the back of the apparatus. A stainless-steel wire mesh belt around the lower roller allowed water to flow from the chips to the ho les.The chips included cedar and cypress chips. Wood chips were dewatered at pressures of 10,20 and 30 MPa. It was found that roller compression can remove water from wood chips with low energy consumption.

GB 2090954 discloses a method and an apparatus in which wood chips are dewateredbetween two endless conveyors between which the wood chips are squeezed. One of theconveyors is a perforated conveyor and a suction means may be provided for applying a reduced pressure or vacuum to the underside of the perforated conveyor.

When compression has been used to dewater wood chips, the effect has not always metexpectations. From WO2014/033156 there is known an improved apparatus in which dewatering of wood chips is carried out by means of compression. The apparatus comprises a first roll and a second roll that form a nip in which water can be pressed out of the rawmaterial, e.g. wood chips. An endless perrneable conveyor is arranged to pass through the nip and carry the raw material through the nip.

DE524055C discloses a roller mill for grinding of sand, ores or the like, wherein the pressing rollers are mounted in eccentric levers, which are adjustable by means of an adjusting device.

W0l70468l0 disclo ses an improved intemal bleeding roller of a liquid extraction machineincludes a cylindrical shaft, a cylindrical sleeve mounted tightly over the cylindrical shaft, anda cylindrical shell mounted onto the peripheral surface of the mounting sleeve. The cylindricalsleeve is provided with a plurality of longitudinal flow channels equally spaced around theperipheral surface thereof. The longitudinal flow channels have increasing cross-sectionalarea towards the edges of the cylindrical sleeve. An outer surface of the cylindrical shell has aplurality of circumferential V-shaped grooves. A set of nozzles are fitted in the respective V-shaped grooves. The nozzles have increasing cross-sectional area axially along its length toprevent clogging of liquid. The design of flow channels and nozzles allow the intemal bleeding roller to efficiently overcome the re-adsorption.

SUMMARYIn view of the above, an object may be to provide an improved apparatus with which distance between rolls may be adjusted.

According to an aspect, this object, or other objects, is achieved by an apparatus fordewatering a f1brous material, also referred to as dewatering apparatus. The apparatuscomprises a second roll and a third roll that form a nip in which water is pressable out of thefibrous material. The second roll has two ends. Each end of the second roll is mounted in arespective bearing. The respective bearing is eccentrically located at a respective location in arespective circular collet. The respective circular collet is rotatably mounted in a respectivecircular mounting frame of a support structure of the apparatus.

A respective transmission at said each end is arranged to linearly extend or retract a respectivebeam to rotate the respective circular collet in the respective circular mounting frame. A distalend of the respective beam is rotatably connected to the respective circular collet and aproximal end of the respective beam is mounted in the respective transmission, which is mounted at the support structure.

According to some embodiments, a common beam is connected between the respectivetransmissions, wherein the common beam is arranged to cause the respective transmissions toextract and retract the respective beams in phase and synchronously.

An advantage may be that the respective transmissions are synchronously adjusted when therespective collets are rotated by means of at least one of the respective transmissions. This may be achieved by means of the common beam.

According to some embodiments, the respective transmission is pivotably mounted at thesupport structure, wherein the respective beam is pivotably connected to the respective circular collet via a respective arm.

According to some embodiments, a cylindric surface of the third roll is provided groovesextending in a rotational direction of the third roll, thereby forrning ridges extending in therotational direction, wherein each ridge presents a respective surface facing a respective radialdirection of the third roll, the respective surface being a respective portion of the cylindricsurface. A width of the respective surface along a longitudinal direction of the third roll isgreater than a distance in the longitudinal direction between opposing edges of the respective surfaces of two consecutive ridges.

According to some embodiments, a depth of the grooves between said two consecutive ridgesis twice the width of the respective surface, the depth being defined as a length from a point ata bottom surface of the groove to a point at the respective surfaces of one of said twoconsecutive ridges. The distance is taken along a radial direction of the third roll, wherein thepoint at the bottom surface of the groove is located at a minimum distance from a center of the third roll.

According to some embodiments, said two consecutive ridges are consecutive along therotational direction of the third roll. According to some embodiments, the ridges have arectangular cross-sectional shape. According to some embodiments, the grooves have arectangular cross-sectional shape. According to some embodiments, the width is about 2-8mm and/or wherein the distance is about 0.5-4 mm and/or wherein the depth is about 6-14 1'I11'I1.

According to a further aspect, there may be provided an apparatus for dewatering a fibrousmaterial. The apparatus comprises a second roll and a third roll that form a nip in which wateris pressable out of the fibrous material. A cylindric surface of the third roll is providedgrooves extending in a rotational direction of the third roll, thereby forrning ridges extendingin the rotational direction. Each ridge presents a respective surface facing a respective radialdirection of the third roll, the respective surface being a respective portion of the cylindricsurface. A width of the respective surface along a longitudinal direction of the third roll isgreater than a distance in the longitudinal direction between opposing edges of the respectivesurfaces of two consecutive ridges.

Thanks to the grooves water accumulating at the nip may easily flow away from the nip, e.g.due to gravity. Thereby, improving dewatering of the fibrous material, since any excess water accumulated at the nip may unnecessarily dampen the fibrous material fed into the nip.

According to some embodiments, a depth of the grooves between said two consecutive ridgesis twice the width of the respective surface, the depth being defined as a length from a point ata bottom surface of the groove to a point at the respective surfaces of one of said twoconsecutive ridges. The distance is taken along a radial direction of the third roll, wherein the point at the bottom surface of the groove is located at a minimum distance from a center of the third roll.

According to some embodiments, said two consecutive ridges are consecutive along therotational direction of the third roll. According to some embodiments, the ridges have arectangular cross-sectional shape. According to some embodiments, the grooves have arectangular cross-sectional shape. According to some embodiments, the width is about 2-8mm and/or wherein the distance is about 0.5-4 mm and/or wherein the depth is about 6-14 1'I11'I1.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows a perspective view from above of an embodiment of a machine arranged aplurality of novel aspects.

Figure 2 shows a side view from of the machine shown in Figure 1.

Figure 3 shows a view from above of the machine shown in Figure 1.

Figure 4 shows a longitudinal Vertical cross-sectional view of the machine shown in Figure 1to Figure 3.

Figure 5 shows some features of an adjustment and control arrangement of the nip inaccordance with an aspect herein.

Figures 6 shows some features of a roll shaft in accordance with another aspect.

Figures 7 and Figure 8 show some features of a novel roll arrangement in accordance with afurther aspect.

Figures 9, Figure 10, Figure 11 and Figure 12 show some features of a novel adjustment andcontrol arrangement of the front roll in accordance with an inventive aspect.

Figure 13 shows a perspective view illustrating an exemplifying raw material supply system.Figure 14 shows some features of a novel support structure in accordance with a still furtherinventive aspect.

Figure 15 shows a perspective view illustrating an exemplifying support structure.

Figure 16 shows a plan view of the exemplifying support structure.

Figure 17 shows a first cross-sectional view of the exemplifying support structure.

Figure 18 shows yet another plan view of the exemplifying support structure.

Figure 19 shows a second cross-sectional view of the exemplifying support structure.

Figure 20 shows a third cross-sectional view of the exemplifying support structure.

DETAILED DISCLOSURE OF THE INVENTION With reference to Figure 1, Figure 2, Figure 3 and Figure 4 there is shown different views ofan apparatus 100 for dewatering fibrous material, e. g. wood chips, comprising a plurality ofinventive aspects. It is to be understood that each of the different aspects may be the subject for its own protection, e.g. by the f1ling of one or more divisional applications.

The apparatus 100 may comprise a basic support frame 8, carrying different modules of theapparatus 100. It is evident for the skilled person that there is no absolute need for a basicsupport frame 8. In the shown example the apparatus comprises such a basic support frame 8supporting a supply chute 10, a band 35, a levelling out device 2, a band adjustment andcontrol arrangement 3, a front roll 40 and a pair of rolls 41, 42 that form a nip N arranged in asupport structure 6 and an adjustment. A pressure adjusting arrangement 5 for adjustmentand/or control of pressure in the nip N may suitable be arranged to force one of the rolls 41 in the nip N against the other 42 such that the nip N is loaded and raw material, e.g. wood chips that pass through the nip N will be compressed by the force in the nip N. Throughout the present disclosure, the front roll 40 may be referred to as a first roll 40 or vice versa.

The band 35 may be a feeder band, and endless band, an endless conveyer belt, a transfer belt or the like.

Each roll 4l, 42 in the nip N is driven by a motor 4l0, 420, which also will assist in drivingthe band 35. Also, a rear roll 43 may be driven by a motor 430 to assist in driving the band, atleast initially prior to a forrning a compressed mat in the nip N. Through the presentdisclosure the rolls 4l, 42 may be referred to as an upper roll 4l and a lower roll 42,respectively. Sometimes, the upper roll 4l is referred to as a second roll 4l and/or the lowerroll 42 is referred to as a third roll 42. Moreover, the rear roll 43 may be referred to as a fourth roll 43. A pressure in the nip N may typically be 40-200 tons, preferably 50-150 tons.

In case of dewatering wood chips, larger wood pieces have previously been cut into woodchips that are to be dewatered in the inventive machine. The wood that has been cut to woodchips may be, for example, trunks from trees, branches of trees or roots from trees. In manypractical applications, the wood chips may be of a size on the order of about 5mm - 20 mm(length, thickness, width) but other dimensions are also possible. It should be understood thatthe raw material may vary as already mentioned, e. g. also be saw dust (i.e. smaller than woodchips), pieces of wood (such as small twigs) that are already so small that they need not be cut into smaller pieces, etc.

The apparatus may comprise the band 35 on which the raw material can be transported intothe nip N. If chips are to be processed, they are preferably spread on the band 35 to form atleast 2 layers on top of the band 35, preferably 2-5 layers, to form a relatively tight mat, i.e.substantially without open through holes, in order to achieve an efficient dewatering of allindividual wood chips. In some applications it may be beneficial to use a band 35 that isperrneable to water and forms an endless conveyor, i.e. a loop, around a front roll 40 and arear roll 43 and is arranged to pass through the nip N such that the endless band 35 can carry raw material through the nip N.

The band 35 may preferably be a metal band/metal belt, but different metal materials can be considered. Preferably, the band 5 is a stainless-steel belt (band). For example, a martensitic stainless-steel belt, preferably a precipitation hardened steel having a relatively high strength(e.g. above 1500 MPA) and hardness (e.g. above 450 HV5), e.g. a belt grade made of lowcarbon, martensitic precipitation hardened, stainless steel. The skilled person may considerwhat other metal materials that could possibly be used, bearing in mind that a suitable metalmaterial should be able to resist wear and be strong enough to allow high pressing forces to be used.

One or a plurality of the rolls 40, 4l, 42, 43 may be a drive roll/s that drives the band 35.

The choice of material and dimensions for the band 35 partly depend on the desired qualitiesof the conveyor. The conveyor must have a certain minimum strength and some ability toresist wear and abrasion. At the same time, it should be flexible and sufficiently perrneable towater. It has been found that the endless conveyor may suitably be a steel band with athickness in the range of 0.5 mm - 2.5 mm, preferably a thickness in the range of 0.8 mm - 2mm. Suitably, the band 35 has perforations with a diameter in the range of 0.5 mm - 5.0 mm,preferably in the range of l.0 mm - 3.0 mm. Suitably, the open area of the band is in therange of 5% - 50%, preferable an open area in the range of 10% - 30 % and even more preferred an open area in the range of l5% - 25%.

Thereby, a good perrneability to water is achieved while the endless conveyor may still havesufficient strength. The perforations l5 may have a circular (round) shape and are preferablypositioned according to an equilateral triangle hole pattem. A band 35 with such perforationsmay have a good perrneability to water, and also assists in moving wood material through thenip N thanks to the combination of a great number of relatively sharp “grabbing” edges(formed by each hole) that have a high strength. Hence, these features assist in enabling theraw material to be moved into and through a nip Nl where the high linear load may otherwisecause diff1culties. Therefore, the perforations can contribute to increasing the output of the inventive machine.

In order to improve durability of the band 35 it may be beneficial to use a larger diameter DTof the tuming rolls 40, 43 than the diameter DN of the rolls 4l, 42 in the Nip, since fatigue ofthe band 35 is related to bendability. The thicker the band the larger must the diameter DT ofthe tuming rolls 40, 43 be to obtain same life expectancy. Since the band 35 must have a certain thickness to withstand the forces created in the nip, it is therefore norrnally an advantage to combine as mentioned above, to combine good strength, compactness and efficiency.

The band 5 may be driven at a speed in the range of 0.5 m/s - 5 m/s, preferably a speed in therange of 0.8 m/s - 3 n1/s. This speed is suitable for effective dewatering. At speeds that aretoo high, there is not time enough for the raw material to become suff1ciently compressed. Atspeeds that are too low, the production rate will be unsatisfactory. In one embodimentcontemplated by the inventors, the machine may be operated at a speed of about l m/ s, toproduce about 60-90 m3/hour, when supplying an about 30 mm thick mat into the nip N,implying approx. 20 wet ton per hour at 50% MC (moisture content).

As already mentioned, the wood material is preferably supplied into the nip forrning at least 2layers on top of each other, if wood chips preferably 2-5 layers, if saw dust preferably l0-50layers, to form a relatively tight mat, i.e. substantially without open through holes, in order toachieve an efficient dewatering of all individual wood particles, which mat in anuncompressed condition has a thickness in the range of l5-l00 mm, more preferred 30 -60 1'I11'I1.

A linear load can be applied in the nip N which is in the range of 400 kN/m - l500 kN/m,preferably in the range of 500 kN/m - 1000 kN/m. Such a force is sufficient for effectivedewatering in many realistic cases. Here, it should be added that the required pressure may vary depending on the type of raw material.

In many practical applications, the nip N may have a gap (distance between the press rolls 4l,42) which, during operation, may be on the order of about lmm - l0mm, preferably about 3mm - 6 mm depending on the type of raw material and other factors. Other dimensions are also possible.

As shown in Figure 4, the levelling out device 2 may include a rake, which may even outand/or smoothen out the f1brous material over the band 35, e.g. in the transversal and/or longitudinal direction relatively a moving direction of the band 35.

Thanks to the machine, fibrous material, e.g. Wood chips, can be dewatered Without excessivereabsorption of Water after the press nip and clogging of the perforations through Which Water is sucked out is reduced.

In the table there is shown that very positive results may be achieved by means of the inVention.MCTest Start MC Finish Other[NY] 1%] 1%]For reference only to be used as starting MC forrest of the samples. Material Was not processed.Reference Sample Was dried for 24 h in oven in 103i2 °C 1 63,6 63,6 to determine starting MC.For reference only to be used as starting MC forrest of the samples. Material Was not processed.

Reference Sample Was dried for 24 h in oven in 103i2 °C 2 64,8 64,8 to determine starting MC. 1 63-65 35,1 Pressed once 2 63-65 36,1 Pressed oncePressed once then impregnated With cold oil 3 63-65 25,7 and then pressed again.Pressed once then impregnated With cold oil 4 63-65 26,4 and then pressed again.Pressed once then impregnated With cold oil 63-65 24,6 and then pressed again.Pressed once then impregnated With cold oil,pressed again, then impregnated With hot 6 63-65 18,1 (temperature 200 °C) oil and pressed again.Pressed once then impregnated With cold oil,pressed again, two cycles With impregnation ofhot oil (temperature 200 °C) and pressing to get 7 63-65 13,4 rid of oil.

It is foreseen that this application may be the subject matter for numerous divisionalapplications, having claims focusing on different aspects of the inventive concept, e.g. one focusing on the aspect of A further benef1cial result of the invention is that the processed material will be much softerthan the raw material (e.g. wood chips) and indeed become spongy. Thanks to this outcomethe processed material will be easier to handle in many situations, e.g. in connection withbaling. Test have shown that bales may easily be produced having a density above 1000kg/m3.

Moreover, the fiber material will also become partially def1brated, which may providesignificant advantages, e. g. in connection with pulp production, especially Mechanical Pulp,by reducing the subsequent need of treatment (chemicals and/or power) to achieve sufficient defibration.

Although the inventive method and apparatus is mainly described for treatment of wood chipsit is evident that it may also be used for similar purpose for treatment of other materials, e. g.sawdust, bark, hog fuel, etc. Further the inventive apparatus may also be used for otherpurposes than dewatering, e.g. it may also be used for compressing already dried wood chips,i.e. for densification of the chips. Very dry wood chips having a water content of 12% or lessdo not spring back very much when they are compressed. This can be used to increase thedensity of wood chips such that the wood chips become less bulky. The compressed woodchips may then be transported more easily from one place to another. Such compressed woodchips may be bumed to produce heat. For the purpose of compressing already dried woodchips, the endless conveyor need not be perrneable, and the suction box would probably serve no purpose.

One main advantage of the invention lies in its good capacity for dewatering wood chips. In atest carried out by the inventors, wood chips having a moisture content (MC) of 55-65% weredewatered down to a water content of 28-35%, wherein of course a lower starting MC will help to reach a lower end MC, as is presented the table below. 11 Final StartingMC MC35,8 6535,2 6434,7 6334,1 6233,6 61 33 60 32,5 5931,9 5831,4 5730,8 5630,3 55 Now describing one of the novel inventive aspects of the infeed arrangement as best shown in Figure 2 and Figure 13.

Figure 5 shows a detailed perspective view of the upper roll 41 of the apparatus 100 fordewatering a f1brous material 2. As mentioned, the apparatus 100 comprises the upper roll 41and the lower roll 42 that forrn the nip N in which water is pressable out of the f1brousmaterial 2.

The upper roll 41 has two ends 541, 542. The upper roll 41 typically has an even cylindricalsurface, wherein the upper roll 41 may be referred to as an even roll 41. Each end 541, 542 ofthe upper roll 41 is mounted in a respective bearing 55. The respective bearing 55 iseccentrically located at a respective location within an eccentrically positioned mounting hole540 of a respective circular collet 54, wherein the respective circular collet 54 is rotatablymounted in a respective circular mounting frame 600 of a support structure 6 of the apparatus100. The respective location may be measured from the center of the respective circular collet54, e.g. in the radial direction from the center.

A respective transmission 50 at said each end 541, 542 is arranged to extend or retract arespective lever device 53 to rotate the respective circular collet 54 in the respective circular mounting frame 600. The transmission 50 may be a worrn gear mechanism or the like. A 12 distal end of the respective shaft 520 is connected to the respective circular collet 54, eg.rotatably connected, and a proximal end of the respective shaft 520 is mounted in therespective transmission 50, which is mounted at the support structure 6. The respectivecircular collets 54 are arranged to rotate the respective locations of the two ends 541, 542 inphase and synchronized, whereby due to rotatability of the respective circular collets 54 adistance between the upper and lower rolls 41, 42 at the nip is adjustable. In this manner, it isensured that the distance at the nip remains constant along the longitudinal direction of the lower roll 42.

Preferably, a common input shaft 51 is connected between the respective transmissions,wherein the common input shaft 51 is arranged to cause the respective transmissions 50, suchas linear drive mechanisms, to extract and retract the respective beams 520 in phase and synchronously.

In one example, the respective drive mechanism 50 is fixedly mounted at the support structure6. The respective beam 520 is rotatably connected to the respective circular collet 54 via arespective arm 533. In another example, the respective drive mechanism 50 is rotatably mounted at the support structure 6.

In the shown exemplified embodiment in figure 5, the pressure adjusting arrangement 5comprises a plurality of interacting members 50, 51, 52, 53, 54 on each side of the upper roll41. Merely one side will be described in the following. The transmission 50 is in the form of agear box 50 that transmits torque/rotation from the common input shaft 51 to an output shaft52. Accordingly, via the interacting gear wheels (not shown) within the gearbox the inputtorque will be transmitted to the output shaft 52. A drive member 51A is connected to thecommon input shaft 51 to provide for the desired rotation of the input shaft 51, which in tumis transmitted to the output shaft 52 into a desired transmitted rotation depending on thechosen gear ratio. The common input shaft 51 extends aside of the roll 41 to have its inputgear wheel synchronously connected to both of the gear boxes 50. Preferably the gear ratio issuch to provide a substantial reduction, e. g. 10/1 -100/ 1, to enable easy displacement of thecollet 54 also by the use of relatively low input torque, e.g. manually or a relatively smallmotor. As used herein, rotation refers to at least a partial rotation, i.e. rotation may thus referto a portion of one revolution, one or more revolutions with or without any additional portion of a revolution etc.. 13 The output shaft 52 is connected to a lever member 53 by means of outer threads 520 on theoutput shaft 52 that are interacting with inner threads of a socket 530 attached at one end 532of the lever 53. The lever 53 has its opposite end fixedly attached to the collet 54, eg. bymeans of a pair bolts 53 l. Accordingly, rotation of the upper shaft 52 will be transforrned tomovement of the socket 530 and thereby also move the lever 53, which in tum will rotate thecollet 54. Since the collet 54 is rotatably mounted within a circular mounting 600 in the frameof the support structure 6, the lever 53 will follow the rotating movement of the collet 54. Asa consequence, the shaft 520 will slightly pivot during rotation of the collet 54, which isenabled by having the transmission 50 pivotally attached to the support structure 6, e.g. to anextended part 6l lA of a cantilever 6l l. Accordingly, the lever member 53 will move forthand back depending on the direction of rotation of the output shaft 52, which in tum is dependent on the direction of rotation of the input shaft 5 l.

The shaft 4l0 of the upper roll 4l has each end mounted within said collet 54 by means of abearing 55 that enables friction free rotation of the roll 4l in relation to the collet 54. Thecentre C54 of the mounting hole 540 within the collet 54 does not coincide with the centreC4l of the outer periphery of the collet. Accordingly, the shaft 4l0 of the roll is eccentricallypositioned in relation to the centre C4l of the collet 54. As a consequence, the position of theroll 4l will be altered when the collet 54 is rotated. The aforementioned respective locationmay thus be defined by a distance from the center C4l to the center C54, e.g. in the radialdirection from the center C4l. Accordingly, the pressure adjustment arrangement 5 providesfor the ability to adjust the nip gap ND and thereby also adjust the pressure excerpted onto themat of f1brous material by the rolls 4l, 42 in the nip.

In the figure it is shown that the driving member 5 lA of the input shaft 5 l, is in the form of awheel that may be operated manually. It is evident for the skilled person that this driving member may also be driven by a motor, e.g. an electric motor or hydraulic motor.

Figure 6 shows an exploded view illustrating details of an exemplifying mounting assemblyfor installation of a roll, such as any one of the front, upper, lower and rear rolls 40, 4l, 42, 43or the like. The exemplifying mounting assembly makes it easy to change a roll. Anadvantage of the exemplifying mounting assembly is hence that a roll, such as the upper roll 4l, may easily be mounted at or de-mounted from the support structure 6. A shaft 4l l, about 14 which the upper roll 41 is rotatable, is rotatably supported by the respective bearings 55. Theshaft 411 includes a respective bearing support 416 at which the shaft 411 is held in place inthe support structure 6. At a distal end 415, a first diameter of the shaft 411 may less than asecond diameter at a midpoint of the shaft 411. Distally of the one of the respective endportions 461 that is closest to the distal end 415, the shaft 411 may be tapered such that thediameter of the shaft 411 smoothly converges towards the first diameter. When the shaft 411is extracted in the axial direction of the roll 40, 41, 42, 43, the roll 40, 41, 42, 43 may bedemounted from the apparatus 100. Furthermore, upon mounting of the roll 40, 41, 42, 43, itmay be held in place, e.g. by a truck or robot grabbing around the roll without obstructing theends thereof, next the shaft 411 is inserted into the roll 40, 41, 42, 43 to rotatably fasten it in the apparatus 100.

In the shown exemplified embodiment in figure 6 there is shown a preferred embodiment ofmounting of the rolls 41, 42 in the nip, by showing an exploded view of preferred mountingparts of the roll shaft 411 of the upper roll 41. The shaft 411 has a driving end 415 ontowhich the driving power from the motor 410 is applied. Further there are two bearingsupporting areas 416 on each side that rotatably support the shaft 410 by means of bearings55, within the collets 54. To fixate the roll body 412 on the shaft there are arranged clampingmembers 57. Locking members 59 are arranged to axially fixate the shaft 411 in combinationwith attachment flanges 59. The arrangement facilitates the possibility of removing a roll 41by means of suspending the roll body 412 in position, removing fixating members andthereafter pulling the shaft 411 out of the roll body 412 sideways, such that the roll 41 maythen be lifted out of the support structure 6.

Figure 7 shows the lower roll 42 of the apparatus 100 illustrated above. As mentioned, there is thus provided an exemplifying apparatus 100 for dewatering f1brous material 2. Theapparatus 100 comprises the upper roll 41 and the lower roll 42 that form the nip N in whichwater is pressable out of the f1brous material 2.

In the cross-sectional new of Figure 7, the respective circular collets 54 are referred to as afirst circular collet 54A and a second circular collet 54B that are arranged peripherally of therespective bearing 55.

At the distal end 415 of the shaft 411, which projects from the support structure 6, a motor 420 may be installed for rotational driving of the lower roll 42.

In figure 7 there is shown a cross sectional view of the lower roll 42 in the nip and itsattachment into the support structure 6. There is shown the position 416 (see Fig. 6) of thebearings 55 on the shaft 41 l, which is identical for both rolls 41, 42, as many other parts ofthe mounting arrangement. However, for the lower roll 42 there is no eccentrically adjustablecollet 54 but instead fixed collets 54A, 54 B. Hence, the collets 54A, 54B are preferably not rotatable, within the mounting hole of the frame 6.

Figure 8 shows a detail of the lower roll 42 shown in Figure 7. The lower roll 42 ischaracterized by that a cylindric surface of the lower roll 42 is provided grooves 425extending at the periphery of the lower roll 42 and transversally in relation to, preferablyperpendicular to, the axial direction of the lower roll 42, thereby forrning ridges 426extending in the rotational direction. Each ridge presents a respective surface 42A facing arespective radial direction of the lower roll 42, the respective surface 42A being a respectiveportion of the cylindric surface. A width v of the respective surface along a longitudinaldirection of the lower roll 42 is greater than a distance t in the longitudinal direction betweenopposing edges of the respective surfaces 42A of two consecutive ridges 426. In onealtemative there are a plurality of separate circumferentially extending grooves 425, that runperpendicularly in relation to the axial direction of the lower roll 42. In more detail, thegrooves 425 may run along and/or parallelly with a circumference of the lower roll 42. Inanother altemative, there may be one or more circumferentially extending grooves, that run along one or more helical paths.

In one example, a depth d8 of the grooves between said two consecutive ridges 426 is twicethe width v of the respective surface 42A, the depth d8 being defined as a length from a pointat a bottom surface 42B of the groove 425 to a point at the respective surfaces 42A of one ofsaid two consecutive ridges 426. The distance is taken along a radial direction of the lowerroll 42. The point at the bottom surface 42Bof the groove 425 is located at a minimumdistance from a center of the lower roll 42. Said two consecutive ridges are preferablyconsecutive along the rotational direction of the lower roll 42. As described above, the lowerroll 42 may typically have a ribbed cylindrical surface, wherein the lower roll 42 may be referred to as a ribbed roll 42.

According to various examples, the ridges 426 and/or the grooves 425 have a rectangular cross-sectional shape, a polygonal shape, a triangular shape or the like. In some examples, the 16 cross-sectional shape may be formed by a combination of a rectangle and a circular sectorhaving a diameter that is equal to, or almost equal to a side of the rectangle on which thecircular sector may be arranged, such as standing. The circular sector may then form a bottomof a groove. The width V may be in a range from 2-8 mm, preferably 4-6 mm, more preferablyapproximately 5 mm. The distance t may be in a range from 1/2-4 mm, preferably l-3 mm,more preferably approximately 2 mm. The depth d8 may be in a range from 6-l4 mm,preferably 8-12 mm, more preferably approximately l0 mm. As may be seen from Figure 8,the surface 42A of the lower roll 42 is arranged with a plurality of circumferentially extendinggrooves 425. The grooves assist in the de-watering process by means of enabling escape ofthe water being pressed out of the f1brous material in the nip. The water may escape through, or in, the grooves 425 e.g. due to gravity.

In Figures 9, l0, ll and l2 there are shown different views of the front roll adjustmentarrangement 3, basically including the front roll 40 and two parallel support members 300,preferably in the form of vertical support plates, that support the roll 40. The roll 40 isadjustably arranged between the support plates 300 in order to be able to tension the band 35and to be positioned in a correct position during operation. Figure 9 is a side view illustratingdetails in the vicinity of the front roll 40. Figure l0 is a cross-sectional view in the plane D-D of Figure 9. Figure l2 is a cross-sectional view in the plane G-G of Figure ll.

The front roll adjustment arrangement 3 may also include a pivot arrangement 3 l , includingpivot shafts 302. The pivot shafts 302 are attached to a base frame of the machine, see e. g.beams 63, 68, and enables the support plates 300 to pivot such that the angle ot between thehorizontal and the band 35 up to the nip between the two nip rolls 4l, 42 may be adjusted.Preferably this angle ot should be in the range of 3°-23°, more preferred 50-200, most preferred5°-l5°, to optimise, or at least improve, the process according to a preferred embodiment ofthe invention. An advantage with having the angle ot of the band 35 adjustable is that the rawmaterial may then be supplied to the nip between the rolls 4l, 42 and always have the lowerroll 42 supporting the raw material in connection with contact with the surface of the upperroll 4l. Accordingly, the pressure exerted by the upper roll in a downward direction will thenhave the surface of the lower roll 4l as the support. This function is described based onhaving the two rolls 4l, 42 positioned along a vertical line, implying that it is not required thatthe band 35 is positioned at an angle in relation to the horizontal, but rather at an angle ot in relation to aligned norrnals through the nip of the two rolls 4l, 42. Accordingly this effect 17 may also be achieved by instead having the band 35 horizontal and arranging the alignednormal of the rolls along an angle ot that is offset in relation to the vertical. If not this angle otis arranged within the nip there is a risk that the pressure exerted by the upper roll when material is entering the nip may cause damages to the band 35.

Further, the diameter DN of the rolls 41, 42 in the nip, i.e. press rolls, may have an influenceregarding efficiency and also cost. The smaller diameter DN the larger peak pressure may beachieved with the same amount of linear load. Tests have shown that the diameter DN maypreferably be in the range of 400-1200 mm, more preferred 600-1000 mm. Preferably thediameter DT of the retum rolls 40, 43 are larger, i.e. DT > DN. The diameter DT of thetuming rolls 40, 43 (rear roll and front roll) may preferably be in the range of 500 - 2000 mm,more preferred 600-1500 mm The support sides 300 of the arrangement to hold the front roll 40 in a desired position alsoincludes adjustment units 313, 314 having one part in contact with the base frame of themachine and another part attached to the support sides 300 and an adjustable member inbetween, such that the desired angle ot of the band 35 may easily be adjusted, before a fixation arrangement 303, e.g. screws, are secured, passing through curved passages.

There is also a conveyer tensioning arrangement 31 which makes it possible to position eachend on the shaft 401 carrying the roll 40 independent of the other end along linear guides 311,312. Preferably, there are arranged two linear guides 311, 312 extending in the longitudinaldirection of the machine on each inside of the support sides 300. Each linear guide 311, 312comprises in a male part 311 that is interf1t with a female part 312, wherein the one part isfixed to the inside of each support side 300 and the other part is moveable relative the otherpart 312 and fixedly attached to a roll support 305. Each roll support 305 accordingly carriesat least one, preferably two, guide members 311 on their outsides. Centrally in the rollsupports 305 there is a through hole arranged with a bearing 310, which in tum carries the end of the roll shaft 401.

Centrally the roll shaft 401 may have a larger diameter arranged for interf1t with attachmentmembers 403, 404, which provide for the possibility of fixating the roll 40 adjustably alongthe central part of the roll shaft 401 and by carrying the roll sides of the body 402 of roll 40.The roll shaft 401 is positioned adj acent one end of the support sides 300 that is opposite tothe attachment of the support sides 300 to the base frame of the machine. 18 According to a preferred embodiment of the invention it includes a conveyor tensioningarrangement 34, which preferably is achieved by having each movable roll support 305connected to a tensioning device 33, such as a linear actuator. According to one embodimentthis may be achieved by having each roll support 305 attached to an outer member 330 of alinear actuator 33. The linear actuator has a base 331 that is fixed adjacent the downstreamend of the support sides 300 and includes a gear mechanism that is driven by a motor 306 andwhich transmits the rotation from the motor to provide a linear movement of the moveable member 309 of the linear actuator 33, as is known per se.

Thanks to the tensioning devices, e.g. linear actuators 33, it is possible to tension the band 35at varying desired levels, independently on each side and thereby also at the same time toposition the shaft 401 of the roll 40 to have the band running along the roll surface at aposition that is desired, i.e. norrnally centred on the roll 40. Accordingly, thanks to thisarrangement it is possible to maintain the position of the band within desired limits in atransversal direction to reliable feed the raw material in to the nip between the rolls 41, 42. Asis evident for the skilled person this is achieved by the fact that a slight offset of the roll shaft401 will produce a counterforce from the pre-tensioning of the band 35 which in tum mayproduce transversally directed forces on the band such that it may start be displaced in atransversal direction along the roll surface. A preferred range of adjustment on each side is atleast 30 mm, more preferred 50-100 mm and a preferred range of tension applied is at least 15 kN, more preferred 20 -40 kN.

By adjusting the position of the roll such undesired transversal displacement may be stoppedand by correctly position of the two linear actuators 33 the band will both have a desired pre-tensioning and a desired position on the surface on the roll 40. The mounting part 308C of thelinear actuator 33, which preferably includes a shaft 310, includes a force sensing device, e.g.a pressure and/or tension sensing member. Thanks to having the linear actuator 33 attached tothe support sides 300 in this manner the exact force applied to each side of the roll 40 may beboth measured and controlled, which is a major advantage in order to reliably control adesired tension of the band 35 and also to position the band 35 correctly in relation to the surface of the roll.

There are also shown a plurality of cleaning units 315, 316, 317, arranged to clean the band35 and the front roll 40, respectively. Preferably each cleaning unit includes a shaber, and more preferred combined with water flow or spray to enhance the cleaning effect. This 19 combination is especially preferred for a first cleaning unit 315 that cleans the inside surfaceof the band 35. In the shown embodiment there is a second shaber 316 that cleans the surfaceof the front roll 40 and a third shaber 317 that cleans the outside surface of the band 35. The third shaber 317 is preferably supported by a separate support device 301. (see Figs. 1 and 2).

In Figure 13 there is shown the raw material supply system 1 in more detail, in a perspectiveview from above. It is shown a supply chute 10, e. g. a chip chute, having a substantiallyrectangular cross section enclosing an upper space 10A and a lower space 10B (shown inFigure 2), wherein the cross section of the lower space 10B is larger than the upper space10A, by both having the same transversal width L10C and the lower space 10B having alarger longitudinal width L10B (e.g. 1200- 2000 mm), than the longitudinal width L10A (e.g.1000-1500 mm) of the upper space 10A. Within the lower space 10B, at the bottom level ofthe supply chute 10 there is arranged a raw material feed system 11, which includes aplurality of screw feeders 11 A, 11B, 11C, preferably three. The plurality of screw feeders 11A, 11B, 11C are arranged in parallel having a driveshaft 110 arranged in the length directionof the machine. The driveshafts 110 are driven by a motor 118 via a gear box attached to afirst side 10C of the chute and have their far ends positioned at a second side of the chute, at an outlet opening 117 at the outlet end of the lower space 10B.

Helical plates 111 are attached to the shaft 110 preferably having a radius, R111 that is in therange of 1,5-3 times the radius R210 of the shaft 210. The pitch of the helical blade 211 issuch that it is larger than the shaft diameter, preferably larger than 2 x R210. The length L110,(substantially the same as the longitudinal width L10B) of each screw 11A, 11B, 11C is suchthat it preferably includes between 5 and 15 tums exposed within the space of the chute 10.The total diameter D211, 2 x R211 is preferably within the range 7 x D211 > L10B > 2 xD211. The positions of the helical blades 111 are preferably phase shifted, i.e. an edge facinga neighbouring screw feeder 11 A, 11B, 11C will be positioned in between two opposingedges of neighbouring screw feeder, which implies that they may be positioned very close toeach other (even slightly overlapping) when they rotate (all rotate in the same direction) andmaintaining a gap between the edges, i.e. without risk of j amming raw material between them.The transversal width L10C of the chute 10 is preferably within the range 0,8 (n x D211) to 1,2 (n x D211), where n is the number of screw feeders.

The screw feeders 211 are positioned above a supply surface 114 at the bottom of the chute . the screw feeders 11A, 11 B, 11C will push the raw material along this supply surface 114 and push the raw material, out through the opening 120 from the lower space 10B. Preferablythe output edge 114A of the supply surface 114 is positioned along the same vertical line asthe outlet opening 117. The output edge 114A is positioned slightly above the band 35 andpreferably positioned further in the longitudinal direction than vertical centreline through thecentre of the front roll 40. Thanks to this arrangement the screw feeders 11A, 11B, 11C mayfeed raw material on to the band 35 and at a position that safeguards forward transport of the raw material.

The supply chute 10 is supported by a fixed lower support plate 118. On top of that supportplate 118 there is arranged an adjustable support plate 119, which is slidably arranged in thelongitudinal direction in relation to the fixed support plate 118. Thanks to this arrangementthe front edge 114 A of the outlet from the supply chute 10 may be adjusted in the lengthdirection. This feature may be a significant advantage in applications where the position ofthe front roll 40 may be adjusted, e. g. by pivoting the support structure 30 to have the angle uof the band 35 at varying angles. Accordingly, if a lower position of the front roll 40 is chosenthe position of the outlet 114 A may be adjusted and moved in direction to the nip to have thelower edge of the outlet 114 A with a desired gap in relation to the band 35. Further, it isforeseen that this function may also be beneficial in connection with feeding of raw materialto another kind of infeed device than a band 35, e.g. an infeed device substantially merely including the rolls 41, 42 of the nip N.

The supply surface/bottom portion 114 of the supply chute may preferably be in the form of atube half (not shown) for each screw 110, 111. The reason for this is that the preferredembodiment of screw feeders 11 need no support at their frontends, i. e. no need of barring.However, in many applications for use of the invention there is a need of keeping the screwfeeders 110, 111 in desired positions lengthwise, i.e. a part not to interfere with each other.Accordingly, such tube halves have an inner diameter that is adapted to the diameter of thehelical blades 11 and are fixedly attached to each other not to leave gaps in between the parallel tube halves.

Furthermore, preferably the speed of each feeder tube 11A, 11B, 11C may be independentlycontrolled, to establish desired homo geneity of the raw material that is delivered on to theband 35. The reason for this is that the raw material supplied via the chute 10 may have atendency to provide larger supply of raw material onto one side than the other, if the screw feeders are driven with the same speed. Accordingly, this may be adjusted by adjusting the 21 speed of the screw feeders 11A, 11B, 11C to provide for a more homogeneous supply of raw material on to the band 35.

Further as noted there is preferably arranged retaining plates 201 on each side of the opening117 of the supply chute, having the main purpose to retain the raw material on the band 35. Ina preferred embodiment these retaining plates 201 are made in a transparent material such that the raw material supplied to the band 35 may easily be observed visually.

Moreover, it is shown that on top of the moveable or adjustable support plate 119 at the backend of the supply chute 10 there is a pivotal support member 115 having a support part 115Aattached to the supply chute bottom 114 and a pivot shaft 115 B that is rotatable fixatedwithin a support foot 115 C. This arrangement will enable the outlet 114A to be adjustablypositioned by pivoting into a desired angle ß in relation to the infeed device (as indicated inFigure 2 by a dotted altemate position of the bottom 114“), e. g. a band 35. Further, it isforeseen that this pivotal function may also be beneficial in connection with feeding of rawmaterial to another kind of infeed device than a band 35, e.g. an infeed device substantially merely including the rolls 41, 42 of the nip N, such as a dewatering nip.

At the other side of the moveable support plate 119 there is arranged a measuring supportdevice 116, which is made possible thanks to having at least the bottom of the supply chute 10movable in the vertical, e. g. by means of a pivoting design as mentioned above. By means ofthis measuring support device 116 the amount/ load of raw material being supplied can bemeasured in real time. This measurement may provide relatively exact figures regarding theamount of raw material being supplied, since the moisture content of the raw material isknown and thereby also the density and which in tum provides the possibility to calculate theexact amount being supplied. Preferably tension gauges or load cells are being used within this measuring support device 116.

The front end of the lower chute space 10B is preferably totally open, since in a preferredembodiment there is no need of any support structure for the screw feeders at the outlet end114 A. However, it may be preferred to arrange an upper limit plate (not shown), below theupper wall of the lower space 10B to adapt the height of the space 10B to the size of the screw feeders.

Figure 14 through Figure 20 illustrate various parts and features of an exemplifying support structure 6. Figure 17 is a combined side view and cross-sectional view along a plane C-C in 22 Figure 16. Figure 19 is a cross-sectional view along a plane A-A in Figure 18 and Figure 20 is a partial cross-sectional view along planes B-B in Figure 18.

A support structure 6 for supporting rolls 42, 43 for dewatering wood material 2 delivered atthe band 35 to a nip N forrned between the rolls 42, 43 is provided. The support structure 6 isarranged to allow insertion and removal of the transfer belt by displacement of the band 35along an axial direction of the rolls 42, 43 when installed in the support structure 6, without need to demount any of the rolls 42, 43.

The support structure 6 comprises a first side wall 60A that is perpendicular to the axial direction of the rolls 42, 43 when these are installed in the support structure 6.

A first cantilever 611 and a second cantilever 610 extend from the first side wall 60A.Preferably the first cantilever 611 forms a separate part, which is supported by an upper part613 of the transversal wall 61. (see Figure 19) More preferably, the first cantilever 611 is inthe form of a plate having extension 611A on both sides for attachment of one or more parts50 of the pressure adjustment arrangement 5. As used herein, the term ““cantilever” is used todescribe e. g. a beam or similar element that projects e. g. from a wall, another beam or the like.

With reference to Figure 19, the transversal wall 61 may comprise a rigid back end part 615that forms an integral base portion for the second cantilever 610, e. g. from which the secondcantilever 610 projects. Hence, the second cantilever 610 preferably forms a part of thetransversal wall 61 that is positioned adjacent the centre of the support structure 6 seen in themachine direction. The second cantilever 610 forms a part that is positioned above a lowerwall base 614, wherein both the second cantilever 610 and the lower wall base 614 maypreferably be connected by the rigid back end part 615, e.g. such that the second cantilever610 and the lower wall base 614 becomes integrated with each other, i.e. forrning an integralpart. Between the second cantilever 610 and the lower wall base 614 there is a passage 616,providing space in the transversal wall 61 for passage of the band 35. The lower wall base614 is connected to the third wall portion 66, e.g. via a backing member 64. Accordingly, thethird wall portion 66 is connected to the first side wall 60A via a lower, transversal wall base 614 and preferably one or more beams 63, 68, to form a base frame or the like.

The support structure 6 comprises a second side wall 60B located opposite relatively the rolls42, 43 to the first side wall 60A and parallelly to the first side wall 60A. The second side wall60B comprises a first wall portion 67, a second wall portion 65 and a third wall portion 66. A 23 through hole 604, may be provided in the first wall portion 67, for the common shaft 51 shown in Figure 5.

The first wall portion 67 is connected to the first side wall 60A via the first cantilever 611.Further, the first wall portion 67 may be more stably connected by means of being connectedby a third cantilever device 601, 605. Also, the third cantilever device 601, 605 may be used to support another unit of the machine, e.g. the levelling out device 2.

The second wall portion 65 is connected to the first side wall 60A via the second cantilever6 1 0.

The third wall portion 66 is connected to the first side wall 60A, via beams 63, 68, to form arigid base frame. The base frame may have feet 660 for fixed attachment to a a basic support frame 8.

A first gap G4 (see Fig. 14) is formed between the first wall portion 67 and the second wallportion 65. A second gap G6 (see Fig. 14) is formed between the second wall portion 65 andthe third wall portion 66.

The first wall portion 67 and the second wall portion 65 are provided with respectiveattachment interface halves 673, 653 on one side each of the first gap G4, forrning a jointattachment interface 673/ 653 for attachment of a holding arrangement 69. The holdingarrangement 69 bridges the first gap G4, such that it keeps the first wall portion 67 and thesecond wall portion 65 in positions during use, i. e. transfers forces (mainly tension) betweenthe first wall portion 67 and the second wall portion 65. Preferably, the holding arrangement69 keeps the first and second wall portions 67, 65 in fixed positions, e. g. relatively each other.The holding arrangement 69 prevents the first gap G4 from being extended, such as enlarged,widening or the like. Preferably, the holding arrangement 69 comprises two holding members69A, 69BB (see Figure 20) which are clamped onto a respective side of the attachmentinterface at a respective side of around the gap G4, e. g. by bolts in bolt holes 654, 674, 694 oneach side of the gap G4. This means that the holding members 69A, 69B comprises a firstholding member 69A and a second holding member 69B. More preferably, the face 693 ofeach holding member half 69A, 69B has recesses/protrusions forrning edges 694, whichinteract with corresponding edges 655 of the attachment interfaces 673, 653, respectively,such that said edges 655, 695 assist in keeping the two wall portions 67, 65 in positions. In theexemplary embodiment these edges 655, 695 are in the form of longitudinal planar surfaces, being planar in two orthogonal directions, extending parallelly with the extension of gap G4. 24 Moreover, the middle bolt 696 of the holding arrangement 69 runs, preferably freely, withinthe first gap G4, to interconnect the holding members 69A, 69B, aka a first and a secondholding member. In this manner, the middle bolt 696, or bolt 969 for short, facilitatesmounting and demounting of the holding arrangement 69, since the second holding member69B may thanks to the bolt 696 be guided along the first gap G4, e.g. to where the holdingarrangement 69 may be removed from the support structure 6. An advantage is that the secondholding member 69B is not easily dropped down into the support structure 6, where it would be difficult to reach the second holding member 69B.

However, it is evident for the skilled person that the surfaces forrning the edges may becurved in the longitudinal extension and fulfil the same function and that the shownmale/female interfit may be reversed. Preferably, the surfaces forrning the edges 655, 694 inthe lateral direction, however, are planar and extend in parallel with the bolt holes 654, 674,694. Preferably there are two parallel surfaces 695 facing towards each other on the holdingmember 69 and two parallel surfaces 655 facing away from each other on the interface 653.The opposite surfaces 657, 677, 697 preferably are tapered, e. g. 10-20°, to enable highprecision fit. In the exemplary embodiment the edges 655, 675 and the opposite surfaces 657,677 in the wall portions 67, 65 are formed by two parallel longitudinal grooves 678, 658 andthe edges 655, 694 and opposite surfaces 697 of the holding members 69 are in the form of protruding ridges along the longitudinal direction of the machine.

The second wall portion 65 and the third wall portion 66 are provided with respective supportinterfaces 659, 669 for interfit of the backing member 64. The backing member 69 bridges thesecond gap G6, such that it keeps the second wall portion 65 and the third wall portion 66 infixed positions during use, i. e. transfers forces (mainly pressure) between the second wallportion 65 and the third wall portion 66. Preferably the backing member 64 comprises apressure withstanding body 640 solid (see Figure 20) and an attachment plate 641, whichbody 640 is introduced into the recess formed by the support interfaces 659, 669 to therebyeliminate the influence of the gap G6. Preferably, the backing member 64 is attached bymeans of bolts 643 by adapted bolt holes 644 in the attachment plate 64l and correspondingthreaded holes in the two wall portions 67, 65, on each side of the gap G6. A handle 642 may be provided for easy removal.

According to another aspect, it is herein disclo sed a method for removing or inserting a band delivering a fibrous material to a nip N formed between at least two rolls 4l, 42 supported by a support structure 6 for supporting said at least two rolls 41, 42. An apparatus 100 fordewatering the fibrous material 2 comprises the support structure 6. The method comprises: 0 demounting a holding arrangement 69 arranged to bridge a first gap G4, forrnedbetween a first wall portion 67 and a second wall portion 65, which are comprised in asecond side wall 60B of the support structure 6, and to keep the first and second wallportions 67, 65 in positions during use, 0 demounting a backing member 64 arranged to bridge a second gap G6 formedbetween the second wall portion 65 and a third wall portion 66, comprised in thesecond side wall 60B of the support structure 6, and to keep the second and third wallportions 65, 66 in fixed positions during use, wherein the method further comprises atleast one of: 0 removing the band 35 from the nip N between the rolls 42, 43 by extracting the band35 in an axial direction of the rolls 4l, 42, and 0 inserting the band 35 between the rolls 4l, 42 by inserting the band 35 in the axialdirection of the rolls 41, 42, and wherein the method further comprises: 0 mounting the holding arrangement 69, whereby the holding arrangement 69 bridgesthe first gap G4 when mounted in the support structure 6, and 0 mounting the backing member 64, whereby the backing member bridges the second gap G6 when mounted in the support structure 6.

According to some embodiments, the demounting of the holding arrangement 69 comprisesuntightening a screw 696, e. g. partially releasing the screw 696, to allow the holdingarrangement 69 to be slid along a longitudinal extension, preferably horizontal extension, ofthe second side wall 60B for removal thereof from the support structure 6, whereby the first gap G4 becomes unobstructed.

According to some embodiments, the demounting of the backing member 64 comprisesreleasing backing screws 643, 644 to allow the backing member 64 to be extracted in anormal direction to the second side wall 60B for removal thereof from the support structure 6, whereby the second gap G6 becomes unobstructed.

According to some embodiments, the removal of the band 35 comprises removing the band from a front roll 40 and a rear roll 43, which are supported by the support structure 6, 26 Wherein at least one of the front and rear roll 40, 43 is niovably arranged in relation to the support structure enabling releasing tension of the band 35.

According to some enibodinients, the insertion of the band 35 coniprises inserting the band 35into the apparatus 100 and onto the front roll 40 and the rear roll 43, and displacing at leastone of the front and rear rolls 40, 43 to reapply tension at the band 35.

Claims (1)

1. An apparatus (100) for dewatering a fibrous material (2), wherein the apparatus (100)comprises a second roll (41) and a third roll (42) that forrn a nip in which Water ispressable out of the fibrous material (2), wherein the second roll (41) has two ends (541, 542), wherein each end (541, 542) of the second roll (41) is mounted in a respectivebearing, wherein the respective bearing (59) is eccentrically located at a respectivelocation (545) in a respective circular co llet (54), wherein the respective circular collet(54) is rotatably mounted in a respective circular mounting frame (600) of a supportstructure (6) of the apparatus (100), wherein a respective transmission (50) at said each end (541, 542) is arranged tolinearly extend or retract a respective beam (520) to rotate the respective circular collet(54) in the respective circular mounting frame (600), wherein a distal end (550) of therespective beam (520) is rotatably connected to the respective circular collet (54) and aproximal end of the respective beam (520) is mounted in the respective transmission (50), which is mounted at the support structure (6). The apparatus (100) according to claim 1, wherein a common beam (51) is connectedbetween the respective transmissions (5 0), wherein the common beam (51) is arrangedto cause the respective transmissions (5 0) to extract and retract the respective beams (520) in phase and synchronously. The apparatus (100) according to claim 1 or claim 2, wherein the respectivetransmission (5 0) is pivotably mounted at the support structure (6), wherein therespective beam (520) is pivotably connected to the respective circular collet (54) via a respective arm (53). The apparatus (100) according to any one of claims 1-3, wherein a cylindric surface ofthe third roll (42) is provided grooves (425) extending in a rotational direction of thethird roll (42), thereby forrning ridges (426) extending in the rotational direction,wherein each ridge presents a respective surface (42A) facing a respective radialdirection of the third roll (42), the respective surface (42A) being a respective portion ofthe cylindric surface, wherein a width (v) of the respective surface along a longitudinal direction of the third roll (42) is greater than a distance (t) in the longitudinal direction 28 between opposing edges of the respective surfaces (42A) of two consecutive ridges (426). The apparatus (100) according to the preceding claim, wherein a depth (d8) of thegrooves between said two consecutive ridges (426) is twice the width (v) of therespective surface (42A), the depth (d8) being defined as a length from a point at abottom surface (42B) of the groove (425) to a point at the respective surfaces (42A) ofone of said two consecutive ridges (426), wherein the distance is taken along a radialdirection of the third roll (42), wherein the point at the bottom surface (42B)of the groove (425) is located at a minimum distance from a center of the third roll (42). The apparatus (100) according to any one of claims 4-7, wherein said two consecutive ridges are consecutive along the rotational direction of the third roll (42). The apparatus (100) according to any one of claims 4-6, wherein the ridges (426) have a rectangular cross-sectional shape. The apparatus (100) according to any one of claims 4-7, wherein the grooves (425) have a rectangular cross-sectional shape. The apparatus (100) according to any one of claims 4-8, wherein the width (v) is about2-8 mm and/or wherein the distance (t) is about 0.5-4 mm and/or wherein the depth (d8) is about 6-14 mm.