FRAME CONSTRUCTION FOR THE PRESS SECTION OF A PAPER MACHINE PROVIDED WITH SEPARATE NIPS

Abstract: Frame construction for the press section of a paper machine, in which said press section there are two or three subsequent and separate press nips (N₁,N₂,N₃) substantially dewatering the web (W). The nips are formed between two opposite press elements, such as press rolls. Through the nips the web (W) runs as supported by a dewatering and/or transfer fabric. The frame construction of the press section comprises a front frame (110) and a rear frame (130) separate from each other, between which a space (T) open at the top is provided. This space (T) is arranged so as to be utilized in the replacement of both the upper press and/or transfer fabrics (20,30,31) and of the press rolls. At least the upper roll (24,34) of the first or second nip (N₁,N₂) is attached in connection with the rear part of the front frame (110). At least the upper roll (34,54) of the second or third press nip (N₂,N₃) is fitted in connection with the front part of the rear frame (130).

Description: The present invention concerns a frame construction for the press section of a paper machine having separate nips as defined in the preamble of claim 1. In prior-art press sections of a paper machine, such as the applicant's so-called Sym-Press (TM) press section, above the press rolls, both at the service side and at the operating side of the paper machine, there have been horizontal beams which connect the front frame and the rear frame of the press section permanently together. In this connection, and so also in the following description, the front frame means the frame part that is placed, in the direction of running of the web, at the front side, to which said front frame, e.g., the pick-up-suction roll of the press is feed. In a corresponding way, the rear frame means the frame part placed at the rear side of the press section, i.e. closer to the drying section. DE-A-3 541 943 discloses a frame construction and method in a paper machine press section having a compact press roll combination forming at least two press nips through which a paper web runs, the frame construction and method facilitating the removal and replacement of the fabrics and/or press rolls. The frame construction includes a front frame situated before the press roll combination and a rear frame separate from the front frame situated after the roll combination. The space above the roll combination and between the front and rear frames is opened or openable by pivoting an intermediate frame situated above the roll combination into an open position. The replacement of fabrics and press rolls are carried out by utilizing the open space obtained by pivoting the intermediate frame. The intermediate frame comprises two separate frame parts, namely, a front intermediate frame which is pivoted around horizontal articulated joints attached to the front frame, and a rear intermediate frame is pivoted around horizontal articulated joints attached to the rear frame. The intermediate frame is closed by coupling the outer parts thereof to a stationary intermediate frame part mounted, for example, on the bearing housings of the center roll of the press. In connection with the prior-art frame parts of said press sections, difficulties and relatively long standstills have occurred in relation to the replacement both of the press fabrics and of the press rolls. These problems have been increased with an increase in the widths of paper machine, in particular because the press rolls have become ever longer and heavier. The said problems have, for its part, also been increased by the fact that press fabrics which are made of plastic materials and which are rigid in the transverse direction have started being used ever increasingly, which said press fabrics cannot be jammed into a bundle because of their rigidity. The object of the present invention is further development of the frame constructions of press sections provided with separate nips so that the replacement of the press rolls and of the various fabrics can be made considerably easier and faster. The object of the present invention is to provide such a frame construction of a press section provided with separate nips as is essentially shorter than the prior-art frame constructions. By means of the shortening of the frame construction, the investment costs both of the paper machine and of the paper mill can be reduced decisively also in other respects, because a paper machine hall of shorter length in the machine direction is required. In view of achieving the objects stated above and those that will appear below the frame construction for the press section in accordance with the preamble of claim 1 has got the features defined in the characterizing clause of claim 1. Owing to the invention, the faster replacement of the rolls in the press section and in particular of the press and transfer fabrics is quite significant in view of the production output of the paper machine, because the durations of the standstills resulting from the replacements of press rolls and fabrics can be made essentially shorter. In particular the replacements of press fabrics must be repeated at quite short intervals. It is a further advantage of the invention that at the service side of the paper machine an equally abundant space is not needed as when closed frame constructions of a press section are used, because the rolls, at least heavier rolls, can be lifted to above the frame construction of the press section and, if necessary, be turned there to a position parallel to the machine direction. In the latter case, so-called centre lifting of the rolls is preferably used. In the following, the invention will be described in detail with reference to some exemplifying embodiments of the invention illustrated in the figures in the accompanying drawing, the invention being by no means strictly confined to the details of said embodiments. Figure 1 is a schematical side view of a first embodiment of the invention. Figure 2 is a schematical side view of a second embodiment of the invention. Figure 3 illustrates the replacement of fabrics as applied to the press section of Fig. 1. Figure 4 illustrates the replacement of rolls as applied to the press section of Fig. 1. According to a possible exemplifying embodiment of the invention, shown in Figures 1 and 2, the web W is formed on the wire 10, which is either a fourdrinier wire or the carrying wire in a twin-wire former. On the downwardly slanting run of the wire 10 between the suction roll 11 and the wire drive roll 12 the web W is transferred at the detaching line P₁, on the suction zone 22a of the pick-up roll 22, onto the first upper fabric 20, which is both a press fabric that receives water and a pick-up fabric. The fabric 20 carries the web W on its lower face into the first press nip N₁, which is formed between two press rolls 24 and 25. The nip N₁ is provided with two press fabrics, i.e. the said upper fabric 20 and the first lower fabric 40, which is a press fabric that receives water. According to Fig. 1, the upper press roll 24 in the nip N₁ is provided with a hollow face 24′ that receives water. The lower roll 25 in the nip N₁ is a hollow-faced 25′ press roll, whose diameter is preferably slightly larger than the diameter of the upper roll 24. One of the press rolls 24 and 25 can also be a press-suction roll. One or both of the press rolls 24;25 is/are provided with a drive. In the first nip N₁ the dewatering takes place through both faces of the web W both into the upper fabric 20 and into the lower fabric 40. After the first nip N₁, in the run of the web W, there is a second separate nip N₂, which is formed between two press rolls 34 and 35. According to Fig. 1, the first upper fabric 20 carries the web W on its lower face into the second nip N₂. The circumstance that, after the first nip N₁, the web W follows along with the upper fabric 20 and not with the lower fabric 40 is ensured by means of well-known arrangements. According to Fig. 1, in the second nip N₂ the lower fabric is a particular transfer fabric 50, which, compared to the press fabrics proper, is relatively or fully impervious and which fully or substantially does not receive water. Thus, in Fig. 1, the dewatering takes place in the second nip N₂ primarily towards the first fabric 20, i.e. upwards. Owing to the surface properties (smoothness and adhesion) of the transfer fabric 50 and owing to arrangements that will come out later, according to Fig. 1, the web W follows along with the transfer fabric 50, which carries the web W into the third separate dewatering press nip N₃ in the press section. According to Fig. 1, the second upper fabric 31 is a press felt which receives water and which runs through the nip N₃. The upper fabric 31 is guided by the guide rolls 33,33a and 33b and reconditioned by the devices 67. According to Fig. 2, after the first nip N₁, the web W is arranged to follow along with the first lower fabric 51, which carries the web W on its upper face into the second separate nip N₂. This nip N₂ is formed between two press rolls 34 and 35, of which the roll 35 is provided with a hollow face 35″, and so also the roll 34 is provided with a hollow face 34′. In Fig. 1, the second nip N₂ is also provided with two fabrics, and its lower fabric is the said first lower fabric 51, which is a press fabric that receives water and is pervious to water, e.g. an ordinary press felt. According to Fig. 2, the upper fabric in the second nip N₂ is a press felt 30. According to Fig. 2, in the nip N₂, the dewatering takes place both upwards and downwards. After the nip N₂, it is ensured, e.g., by means of the felt angles or by means of a suction device that the web W follows along with the upper press felt 30, on which it is passed into the third separate nip N₃ in the press section. According to Fig. 2, the third nip N₃, which is a separate nip and the last substantially dewatering nip in the press section, is formed between two press rolls 54 and 55, one of which is provided with a hollow face 54″ and the other one with a smooth face 55′. According to Fig. 1, in the third nip N₃ the lower fabric is a transfer fabric 50, and the upper fabric a press fabric 31 that receives water. According to Fig. 2, the upper fabric is a press felt 30, and after the nip N₃ the web W follows along with the smooth-faced 55′ lower roll 55, from which the web W is detached and transferred as an open draw W p onto the drying fabric 60 in a multi-cylinder dryer. According to Fig. 1, the transfer fabric 50 carries the web W after the nip N₃ onto a transfer-suction roll 62, over whose suction zone 62a the drying wire 60 in the drying section of the paper machine is passed. On the line P2 the web W is transferred, by the effect of the suction zone 62a, from the transfer fabric 50 onto the drying wire 60, onto whose face the web W is made to adhere, being passed over the first drying cylinder 63 or a corresponding lead-in cylinder in the drying section. The web W proceeds its run, being supported by the drying wire 60, as a so-called single-fabric draw at least in the initial part of the drying section. In Figures 1 and 2, the guide rolls of the first upper fabric 20 are denoted with reference numerals 23,23a,23b. Correspondingly, in the direction of running of the web W, the first guide roll of the first lower fabric 40 is denoted with the reference numeral 40, and the other guide rolls with the reference numeral 43. The guide rolls of the second upper fabrics 30;31 are denoted with the reference numerals 33,33a,33b, and the guide rolls of the lower fabrics 50;51 are denoted with the reference numeral 53. According to Figures 1 and 2, a steam box 70 is fitted between the first and the second nip N₁,N₂ to operate against the web W, into which said steam box 70 steam is supplied. The function of the steam box 70 is, in a way in itself known, to intensify the dewatering. In the following, a frame construction in accordance with the invention will be described, which is synergic with the press concept described above and by whose means an easier and faster replacement of press fabrics and press rolls as well as constructional advantages are supposed to be achieved. The frame construction in accordance with Figures 1 and 2 comprises a front frame 110 constructed as supported on the foundations 100 of the paper machine hall, an intermediate frame 120, and rear frames 130 and 140. Moreover, in Fig. 2 there is a third rear frame part 150. At the front side of the front frame, there is a projection part 111, on which the guide roll 23 of the first fabric 20 and the pick-up-suction roll 22 are supported, the latter roll by means of loading arms 29. The front frame 110 is provided with cantilevered transverse beams 112. Moreover, the service-side side frame of the front frame 110 is provided with openable intermediate pieces 115. The intermediate frame 120 comprises cantilevered transverse beams 122. The guide roll 23c of the first fabric 20 and the guide roll 33b of the third fabric 30;31 are mounted on the upper side 121 of the intermediate frame 120 by the intermediate of supports 122A. The side frames of the intermediate frame 120 at the service side are provided with openable intermediate pieces 125. The rear frame 130 comprises cantilevered transverse beams 132 as well as, in the side frames at the service side, openable intermediate pieces 135. It is characteristic of the frame part in accordance with the invention that between the front frame 110 and the rear frame 130, i.e. above the relatively low intermediate frame 120, there is an open space T. In other words, the front frame 110 and the rear frame 130 are not interconnected in the upper parts of the frame part, at least not by means of robust frame beams proper. The said open space T can be utilized in the invention in a number of ways, as will come out in more detail later. As can be noticed immediately from Figs. 1 and 2, at both sides of the open space T there are nips, in Fig. 1 the second and the third nip N₂ and N₃ as well as in Fig. 2 the first and the second nip N₁ and N₂. Moreover, in Fig. 2, there is also an open space T₀ between the former rear frame 130 and the latter rear frame 140, above the nip N₃, through which space T₀ the rolls of the third nip N₃ can be replaced. According to Fig. 1, the press rolls 24 and 25 in the first nip N₁ are mounted inside the front frame 110. The upper press roll 24 is attached to an articulated intermediate part 27, which can be displaced by means of power units 28 for the purpose of opening and closing and loading of the nip N₁. According to Fig. 1, the upper roll 34 in the second nip N₂ is supported on an articulated intermediate part 37, which can be pivoted by means of power units 36 so as to facilitate the replacement of the felt 20 or, if required, so as to open the nip N₂. The loading of the nip N₂ takes place primarily by means of the power units 59 of the lower roll 35. According to Fig. 1, the upper roll 34 in the second nip N₂ is mounted on the rear side of the front frame 110. The lower roll 35 of the second nip N₂ is supported on intermediate parts 58, which can be displaced by means of the power units 59 so as to open and to load the nip N₂. Further, according to Fig. 1, the upper roll 54 of the third nip N₃ is mounted in stationary bearing supports placed on the front side of the rear frame 130. On the other hand, the lower roll 55 of the third nip N₃ is supported on intermediate parts 56, which can be pivoted around an articulated joint by means of power units 57 in connection with the intermediate frame 120 so as to load and to open the nip N₃. In Fig. 1, the transfer-suction roll 62 is mounted on the rear frame 140 by means of stationary bearing supports, and the guide roll 53 for the fabric 50, placed underneath the roll 62, is attached to articulated intermediate parts 65, which can be pivoted by means of power units 66 in connection with the intermediate frame 120. According to Fig. 2, the first nip N₁ is placed in the same location as the second nip N₂ in Fig. 1. According to Fig. 2, the upper roll 24 of the first nip is mounted on intermediate parts 37, which are connected to the front side of the front frame 110 by means of articulated joints 39, being pivoted by means of power units 36. In Fig. 2, the intermediate frame 120 is, in the machine direction, longer than in Fig. 1. According to Fig. 2, the upper roll 34 of the second nip N₂ is mounted on intermediate parts 71, which are loaded by power units 72. The intermediate parts 71 are mounted at the proximity of the front side of the rear frame 130 by means of articulated joints 73 placed thereat. According to Fig. 2, the third nip N₃ is placed above the rear frame 140. The lower roll 55 of the third nip N₃ is mounted on the rear frame 140, and the upper roll 54 is mounted on intermediate parts 74, which can be pivoted by means of power units 75 around the articulated joint 76. The said joint 76 is placed in connection with the rear side of the rear frame 130. Finally, the frame part includes a third rear frame 150, to whose front side the transfer roll 62 and the guide roll 33c for the fabric 30 are mounted permanently. In the following, with reference to Fig. 3, replacement of the different fabrics in connection with the frame part in accordance with the invention will be described. When the upper fabric 20 is being replaced, the old fabric is removed and the intermediate pieces 115 are opened so that free intermediate spaces 115A are opened at the side of the service side of the front frame 110. The suction roll 22 is displaced to the open position 22A. The press rolls placed inside the fabric loop 20 are shifted to the positions 24A and 34A that open the nips N₁ and N₂ by pivoting the intermediate parts 27;37 by means of the power units 38;36. In order that all the rolls to be placed inside the loop of the fabric 20 could be brought sufficiently close to each other, the upper guide roll 23a, which is supported on the tensioning means 25, is displaced to its parking site to position 23A. Likewise, the other guide roll 23b placed above the front frame 110 is displaced to the parking site in position 23B, supported on the projection part 111 of the frame. The roll 23c is displaced along the route C to the position 23C. When the pick-up point P₁ and the nips N₁ and N₂ are open and when the rolls 23a,23b and 23c are in their inner positions 23A,23B and 23C while the intermediate pieces 115 are open, the fabric loop is passed through the intermediate spaces 115A at the side frame at the service side so that it forms a loop 20A as shown in Fig. 3, having been opened from the fabric roll 200, which is placed on the replacement pole 205. The replacement pole 205 is supported from both of its ends by means of lifting wires 210, which are attached to the traverse crane (not shown) in the paper machine hall. Hereupon the loop 20A is spread out by unwinding the fabric 20 from the twofold roll 200 to its full width and length by alternatingly displacing the guide rolls 23A,23B and 23C to their normal operating positions along the routes A, B and C. After the fabric 20 has been spread out and tensioned, the pick-up point P₁ is closed and the nips N₁ and N₂ as well as the intermediate pieces 115 and the fabric 20 are tightened. When the first lower fabric 40 is being replaced, the guide roll located in the basement space is displaced to the upper position 42A, the intermediate pieces 115 are opened, and the fabric loop 40A is passed from the roll 400 to around the beams 112,113, the press roll 25 and the guide rolls 42 and 43, whereupon the intermediate pieces 115 are closed, the roll 42A is displaced into the basement space, and the fabric 40 is tensioned. In connection with the second lower fabric 50, it is particularly advantageously possible to utilize the constantly open space T placed between the front and rear frames 110 and 130. In order to open the space T completely, the foremost guide roll 23c of the fabric 20 is displaced along the route C to the parking site to the position 23C in connection with the rear side of the front frame 110. Correspondingly, the foremost guide roll 33b of the second upper fabric 31 is displaced along the route D to the parking site 33B in connection with the upper part of the rear frame 130. Hereinafter, when the nips N₂ and N₃ and the intermediate pieces 125 are in the open position and when the roll 53 is in the inner position 53A having been pivoted by means of the power unit 66, the fabric loop 50A is passed to around the press and guide rolls to be placed inside the loop 50A. The guide roll 76 or guide rolls placed in the basement space is/are displaced to the upper position 76A above the intermediate spaces 125A, so that the roll becomes placed inside the fabric loop 50A. The roll 500 of the fabric 50 is supported on the replacement pole 505. The replacement pole 505 is supported from both ends by means of lifting wires 510, which are supported by the traverse crane operating at the ceiling of the paper machine hall. At the same time as the fabric loop 50A is widened by unwinding it from its roll 500, the guide roll or guide rolls 76A are displaced to the lower position and the fabric 50A is spread out to its full width and length, whereupon the intermediate pieces 125 and the nips N₂ and N₃ are closed, the guide roll 53A is shifted to its normal position, and the fabric 50 is tensioned. The second upper fabric 31 is replaced so that the old fabric is removed, the intermediate pieces 135 are opened, and the foremost guide roll 33b is shifted along the route D to its parking site in the position 33B. Correspondingly, the rearmost guide roll 33a is shifted along the route E to its parking site at the side of the roll 33B to the position 33A. Hereinafter the fabric roll 300, supported by the replacement pole 305 and by the lifting wire 310 and having been spread out to make a loop 31A, is passed to around the press roll 54 and the guide rolls 33,33A and 33B through the intermediate spaces 135A. Hereupon the rolls 33A and 33B are shifted along the routes D and E to their operating positions while at the same time unwinding the fabric 31A from the roll 300 and spreading it, whereupon the nip N₃ is closed, the fabric 31 is tensioned by means of the tensioning devices 68 of its guide roll 33a. Within the scope of the invention, it is also possible to use seamable press and transfer fabrics. In such a case, the frame parts do not require openable intermediate pieces 115,125 or 135. In the following, with reference to Fig. 4, the replacement of the pick-up roll 22 and of the various press rolls will be described. When the pick-up roll 22 is being replaced, it is in the position 22B and the fabric 20 has been removed. The loops 221 of the pair of lifting wires 220 are attached to the axle journals of the pick-up roll 22B. The lifting wires 220 are attached to the traverse crane of the paper machine hall. The lower roll 25 of the first nip N₁ is replaced so that it is detached from its bearing supports and suspended by means of its axle journals on wire loops 251. Hereupon the roll 25 is lowered onto a roller conveyor 80 or equivalent transfer means, which is supported on the transverse beam 113 and by means of which the roll 25 is pulled out to the service side from inside the frame part of the paper machine. The upper roll 24A of the first nip N₁ is replaced in a corresponding way or, in the traditional way, by slipping it by means of three hooks. The upper roll 34B of the second nip is replaced by utilizing the open space T between the frame parts 110 and 130. After the fabric 20 has been removed, the roll 43B is suspended on the wire 340 loops 341, detached from its bearing supports, and lifted by means of the traverse crane to above the press section while making use of the space T. The lower roll 35 of the second nip N₂ is replaced either by pulling out by means of the roller conveyor 80 resting on the beam 123 or by making use of the space T,after the roll 34B has been removed,by lifting the roll 35, suspended on the loops 351 of the lifting wires, by both of its axle journals. The upper roll 54b of the third nip is replaced by lifting it by means of the lifting loops 541 of the lifting wires 540 while making use of the space T. The lower roll 55 of the third nip N₃ is replaced either by lifting by means of the lifting-wire loops 551 or by pulling it out longitudinally on the roller conveyor 80 resting on the beam 123, aided and supported by the lifting wires 551. In stead of the supporting by the axle journals, which was described above, the press rolls, at least the heaviest ones, can also be lifted as so-called centre lifting, wherein the lifting takes place by means of one lifting wire, which is placed at the vertical plane of the centre of gravity of the roll to be lifted, lifting loops arranged in the form of a downwardly open V being provided around the roll at both sides of said plane. The centre lifting provides the advantage that, by its means, the roll can be turned more freely above the frame construction of the press section to the machine direction, whereby the displacement of the roll becomes easier. The new rolls can be brought to their place correspondingly. The new rolls are brought into their place by performing the operations described above in the reversed sequence. The roll 25 must be brought to its place by pushing it longitudinally into the frame construction on support of the roller conveyor 80 while one of its ends is supported by a wire loop 251 at least at the initial stage of the lifting. The rolls 35 and 55 can be brought either through the open space T or by pushing them in on the roller conveyor 80. In Figures 1 and 2, the length of the said open space T in the machine direction is denoted with L. The length L must be dimensioned optimally, e.g., so that the range of the length L in relation to the diameter D of the press rolls 24,34 is as follows: L = k × D , wherein k = 2 to 5, preferably k = 3 to 4. The invention can also be applied to press sections provided with an extended nip or provided with two separate nips only. In such a case, one of the nips, preferably the latter nip, may be a so-called extended nip. In its details, the press section concept concerned may be, e.g., similar to that described in the applicant's Finnish Patent Applications Nos. 842114 or 852115. In principle, a two-nip solution in accordance with the invention may be, e.g., similar to that shown in Fig. 1 with the first nip N₁ omitted and, e.g., with the third nip replaced by a corresponding extended nip, or, alternatively, similar to that shown in Fig. 1, so that the third nip and the latter rear frame 140 are omitted and the second nip N₂ or both nips N₁ and N₂ are replaced by corresponding extended nips. Also, the runs and the arrangement of the fabrics and the quality of the various fabrics may differ from the above. When the invention is applied, the draw of the web W does not necessarily have to be fully closed, even though a closed draw is advantageous. The nips N₁, N₂ and N₃ may also have larger mutual differences in height than what is shown in the Figures 1 and 2. In the following the patent claims will be given, whereat the various details of the invention may show variation within the scope of the inventive idea defined in said claims and differ from the details given above for the sake of example only.

Claims: Frame construction for the press section of a paper machine having separate nips, in which press section there are, in the direction of running of the web (W) from which water is removed, at least two successive press nips (N₁, N₂, N₃) dewatering the web (W), which nips are formed between two opposite press elements, such as, press rolls, and through which nips (N₁, N₂, N₃) the web (W) runs supported by a dewatering and/or transfer fabric, which frame construction comprises a front frame (110) and a rear frame (130) which are separate from each other, a space (T) which is open from above being provided between said front and rear frames, characterised in that each press nip is formed by a different pair of press rolls, that at least the upper roll (24, 34) or corresponding press element of the first or the second nip (N₁, N₂), in the direction of running of the web (W), in the press section is attached in connection with the rear part of said front frame (110), and at least the upper roll (34, 54) or corresponding press element of the second or the third press nip (N₂, N₃) following the above-mentioned nips (N₁, N₂) in the order of the nips is fitted in connection with the front part of said rear frame (130) so that said open space (T) between the front and the rear frames may be utilized in the replacement of both upper press and/or transfer fabrics (20, 30, 31) and press rolls. Frame construction as claimed in claim 1, characterised in that between the front frame (110) and the rear frame (130), there is an intermediate frame (120), the lower rolls (25, 35) or corresponding other press elements of the first and the second nip (N₁, N₂) (Fig. 2) or the lower rolls (35, 55) or corresponding press elements of the second and the third nip (N₂, N₃) (Fig. 1) being fitted in connection with said intermediate frame (120). Frame construction as claimed in claim 1 or 2, characterised in that the first nip (N₁) is placed inside the front frame (110) and that the press rolls (24, 25) of the first nip are fitted so as to be replaceable by means of transverse pulling out (Fig. 4). Frame construction as claimed in claim 1 or 2, characterised in that the first nip (N₁) is placed in connection with the rear side of the front frame (110) and that the second nip (N₂) is fitted in connection with the front side of the rear frame (130) either stationarily or by the intermediate of intermediate parts (37, 71), which are attached to the front frame (110) and/or to the rear frame (130) by means of articulated joints (39, 73). Frame construction as claimed in claim 4, characterised in that the frame construction includes a rear frame part (140), on which the press rolls (54, 55) or corresponding press elements of the third nip (N₃) in the press section are supported. Frame construction as claimed in any of claims 1 to 5, characterised in that the rearmost guide roll (23c) of the first upper fabric (20) and the foremost guide roll (33b) of the second upper fabric (30) are attached detachably in connection with the upper side of the intermediate frame (120), that said guide rolls (23c, 33b) are fitted so as to be detachable and displaceable in connection with the replacement of press rolls and/or fabrics, the guide roll (23c) of the first upper fabric to its parking site in connection with the front frame (110) to an inner position (23C) and, correspondingly, the guide roll (33b) of the second upper fabric (20) to its parking site in connection with the rear frame (130) to an inner position (33B). Frame construction as claimed in claim 6, characterised in that the upper guide roll or rolls (23a, 23b) to be placed inside the loop of the first fabric (20) are fitted so as to be detachable and displaceable in connection with the replacement of the first upper fabric to inner positions (23A, 23B) and that the outermost and/or uppermost guide roll (33) or rolls of the second upper fabric (30, 31) are fitted so as to be detachable and displaceable to an inner position (33A). Frame construction as claimed in any of claims 1 to 7, characterised in that at least the upper press rolls (34B and 54B) placed in connection with said intermediate space (T) are fitted so as to be detachable and displaceable through said free space (T) between the front and the rear frame (110, 130) to above the frame construction of the press section either as lifting taking place by the axle journals or as so-called centre lifting while the guide rolls (23c, 33b) of the first and the second upper fabric (20, 30, 31) placed between said rolls have been detached and displaced to their parking sites to the inner positions (23C, 33B). Frame construction as claimed in any of claims 1 to 8, characterised in that the press section comprises a first upper fabric (20) within whose loop there are, in connection with the front frame (110), a pick-up roll (22) and at least the upper press roll (24) of the first nip (N₁), that the press section comprises a second upper fabric (30; 31), which is either a press fabric that receives water or a transfer fabric substantially not receiving water, that the guide rolls of the said second upper fabric and at least the upper press roll or corresponding press element of the last nip (N₃) are placed in connection with the rear frame (130), and that the press section comprises at least one lower fabric (50, 51), which is either a press fabric that receives water or a transfer fabric substantially not receiving water and which runs through at least two subsequent nips. Frame construction as claimed in any of claims 1 to 9, characterised in that the guide rolls and press rolls or corresponding press elements that are placed inside the loops of said upper fabrics (20, 30, 31) and lower fabric (51) or lower fabrics (40, 50) are fitted in such a way in connection with the front frame (110), the intermediate frame (120) and the rear frame (130, 140, and 150) that a closed draw is obtained for the web (W) from the pick-up point (P₁) to the drying section (P₂, W p ) of the paper machine.

Inventors: AUTIO, MARKKU
Applicants: VALMET PAPER MACHINERY INC.
Application year: 1988
Main classification: D21F3
IPC codes: D21F3, D21F7