WO2000071814A1

WO2000071814A1 - Method for changing a transfer belt in a paper or board machine

Info

Publication number: WO2000071814A1
Application number: PCT/FI2000/000437
Authority: WO
Inventors: Jorma Laapotti; Timo Pirinen; Juhani Pajula
Original assignee: Metso Paper, Inc.
Priority date: 1999-05-24
Filing date: 2000-05-16
Publication date: 2000-11-30
Also published as: FI991171A0

Abstract

A frame structure that supports rolls (24, 26', 27, 28) of a transfer belt loop (21) comprises a side frame of a tending side (HP) provided with openable and closable intermediate pieces (61) and a side frame of a driving side (KP), which side frames are interconnected by means of transverse beams (54). After a nip or nips (N1, N2, N3) associated with the transfer belt loop has/have been opened and after at least a tension roll (28) of the transfer belt loop has been moved to a change position, the old transfer belt loop is removed. Support of the side frame on the tending side can be accomplished as cantilever support by means of transverse beams or by means of a projecting beam (130) secured to the side frame and projecting towards the tending side. In cantilever support, a new transfer belt loop is brought to the tending side by means of a change device (100), around which the new transfer belt loop has been placed on support of guide members (102) in a geometric form substantially determined by the rolls of the transfer belt loop. In support by means of a projecting beam, a new transfer belt loop has been brought around the projecting beam before the side frame is placed on support of the projecting beam. In both arrangements, the new transfer belt loop is transferred from the change device or from the projecting beam to its position of operation around the rolls of the transfer belt loop through openings (62) which remain after the intermediate pieces have been removed from the side frame of the tending side.

Description

Method for changing a transfer belt in a paper or board machine

The invention relates to a method for changing a transfer belt in a paper or board machine defined in the preamble of claims 1 and 5.

In paper and board machines, ever increasing use is made of transfer belts by means of which closed draws can be provided between different devices of a paper or board machine. Such transfer belts are formed, for example, of a base fabric, on which a substantially water-non-receiving smooth surface layer is formed. The surface layer of the transfer belt is relatively easily damaged by sharp bending, scratches and knocks, so it shall be handled with care in a replacement situation.

The method of changing a transfer belt according to the invention is particularly suitable for changing a short transfer belt loop, for example, in a press section, a calender or a coating device. By a short transfer belt loop is here meant a transfer belt loop of the kind the rolls of which are supported above the floor level of the machine hall and which runs at least for the most part above the floor level of the machine hall. In the case of a transfer belt, such a short loop can be used because the substantially water-non-receiving transfer belt does not clog up and its wear is slight. In connection with a felt loop, a separate bulky washing apparatus is needed for cleaning the clogged felt, and in order to achieve a service life of sufficient duration, the felt loop must be relatively long. In connection with a transfer belt loop, merely a doctor and a washing jet are sufficient for cleaning the surface of the transfer belt. When a short transfer belt loop is used, it is easier to prevent paper materials from getting on the inside run of the transfer belt loop where they would cause damage in the transfer belt when passing through a nip or a doctor area. The purchase price of a short transfer belt loop is, of course, also lower than that of a long transfer belt loop. For example, the compact press provided with a centre roll, marketed by the applicant under the trade name SymPress O™, employs a transfer belt loop which extends to the basement spaces under the machine hall. The transfer belt has been replaced in this kind of arrangement such that the long transfer belt loop is caused to hang on support of a pole in its entire length by means of a crane. A tension roll situated deep in the basement spaces has been lifted by means of a rope hoisting mechanism beneath a centre roll above an intermediate piece placed in a side frame of the centre roll on the tending side. After the intermediate pieces have been opened and the side frame of the tending side has been placed on cantilever support, felt-like protective coverings have been attached to the edges of openings remaining after the opened intermediate pieces for the purpose of preventing the transfer belt from being scratched. After that, the transfer belt loop has been pushed into the machine by moving the crane with its transfer belt from the tending side towards the driving side. A large number of people, as many as 15 persons have assisted in spreading the hanging transfer belt loop, in supporting the lower edge in the area of the intermediate piece beneath the centre roll and in pushing the belt into the openings formed by the opened intermediate pieces.

A transfer belt loop extending to the basement spaces under the machine hall has also been used in the press formed of separate nips, marketed by the applicant under the trade name OptiPress™. The transfer belt loop has been folded double and poles have been placed in the middle of the transfer belt loop and at the ends of the transfer belt loop, after which the transfer belt loop has been wound up into a roll, said three poles being situated inside it. The poles placed at the ends of the transfer belt loop prevent the transfer belt loop from being folded too sharply when it is wound into a roll. When the roll is brought by means of a crane to the tending side of the machine, a small carriage provided with wheels is attached to one pole, to its end closest to the machine, and an unwind device is attached to the other end of the pole. Before the roll is pushed into the machine, it is opened to a suitable length on the floor, on which a protective covering that prevents scratching has been spread out. The belt portion still in the roll with its poles is hoisted to such a position that said small carriage is placed on rails situated on a beam, for example, a cantilever beam, extending through the press section. The belt loop is spread by man power such that it is caused to be pushed inside the machine through the openings which remain after the intermediate pieces have been opened. After the belt loop has been pushed into the machine by supporting and moving the tending-side end by means of the crane towards the driving side and when the carriage at the driving-side end of the belt roll simultaneously moves on the rails of the transverse frame to the driving side, the transfer belt loop is opened by means of the unwind device to its full length, in which connection the lower part of the belt loop falls into the basement spaces. Before installing the belt loop, a tension roll situated in the basement spaces has been carried to the side by means of an apparatus formed of rails, support wheels and hoisting ropes, and when the lower part of the belt loop has been lowered into the basement spaces, the tension roll is moved into the belt loop and coupled to a tensioning device.

The main features of the method according to the invention are set forth in the characterizing clause of claims 1 and 5.

The first embodiment of the invention makes use of a change device around which a transfer belt loop is placed on support of guide members in a geometric form substantially determined by the rolls of the transfer belt loop before the transfer belt loop is brought close to the machine for replacement. The use of such a change device enables preliminary preparation for a change of the transfer belt loop, as a result of which the change of the transfer belt loop is considerably expedited. This means that expensive machine downtime can be shortened. When the replacement of the transfer belt loop takes place by means of the change device, the risk of the transfer belt loop being scratched and damaged is also reduced. Moreover, in the change taking place by means of the change device, fewer persons participating in the change are needed, and the change can be carried out relatively safely.

The second embodiment of the invention makes use of a projecting beam which projects to the tending side and around which the transfer belt loop is placed. In an arrangement like this, cantilever support of the side frame on the tending side of the transfer belt loop is not needed at all, whereby financial savings are achieved. In a compact press section provided with a centre roll, in which no fabric is normally running about the centre roll, the set of frames of the centre roll does not comprise any cantilevering, either. In rebuilding this kind of press section in which the centre roll is provided with a transfer belt loop, it is particularly beneficial to use a projecting beam in replacement of the transfer belt in order that there shall be no need to build an expensive cantilever arrangement for the set of frames afterwards. When a framework is additionally used on the projecting beam, the transfer belt loop having been placed around said framework in a form substantially determined by the rolls of the transfer belt loop, the advantages mentioned above in connection with the first embodiment of the invention are also achieved.

In the following, the invention will be described with reference to the figures in the accompanying drawings, to the details of which the invention is, however, not intended to be exclusively confined.

Figure 1 is a schematic side view of a press section with two nips, in which the method according to the invention may be applied in changing a short lower transfer belt loop used in the second press nip.

Figure 2 is a schematic side view of a press section with one nip, in which the method according to the invention may be applied in changing a short lower transfer belt loop used in the press nip.

Figure 3 is a schematic side view of the press nip provided with a short lower transfer belt loop shown in Figs. 1 and 2 in an operating position, in which the frame structures supporting the rolls of the short transfer belt loop are also shown.

Figure 4 shows the press nip of Fig. 3 in a change position of the transfer belt loop.

Figure 5 is a schematic cross-machine direction view of an arrangement for changing a transfer belt loop, which arrangement is suitable for the situation of Fig. 4. Figure 6 is a schematic cross-machine direction view of another arrangement for changing a transfer belt loop, which arrangement is suitable for the situation of Fig. 4.

Figure 7 is a schematic side view of a compact press section with three nips, in which the method according to the invention may be applied in changing a short transfer belt loop running around a centre roll.

Figure 8 is a schematic side view of a variant of the press section shown in Fig. 7, in which the method according to the invention may be applied in changing a short transfer belt loop running around a centre roll.

Figure 9 is a schematic side view of the press shown in Fig. 7 in an operating position, in which the frame structures supporting the rolls of the short transfer belt loop of the centre roll are also shown.

Figure 10 shows the press of Fig. 9 in the changing position of the transfer belt loop.

Figure 11 is a schematic cross-machine direction view of an arrangement of changing a transfer belt loop, which arrangement is suitable for the situation of Fig. 10.

Figure 12 is a schematic cross-machine direction view of another arrangement of changing a transfer belt loop, which arrangement is suitable for the situation of Fig. 10.

Figure 13 is a schematic side view of another variant of the press section shown in Fig. 7, in which the method according to the invention may be applied in changing a short transfer belt loop running around a centre roll.

Figure 14 is a schematic end view of a framework used in changing a transfer belt. Fig. 1 is a schematic side view of a press provided with two separate nips Nl, N2. The first press nip Nl is a roll nip, which is formed between an upper first recessed- faced roll 12 and a lower second recessed-faced roll 13, and the second nip N2 is an extended nip, which is formed between an upper shoe roll 22 and a lower third recessed-faced backing roll 24. The shoe roll 22 comprises a press shoe 23, which produces the nip load required in the extended-nip zone against the backing roll 24. In the first press nip Nl , a first press felt 10 serves as an upper press fabric and a second press felt 11 serves as a lower press fabric. In the second press nip N2 there is a third press felt 20 serving as an upper press fabric and a transfer belt 21 serving as a lower fabric. In the first press nip Nl , water is removed from a web W in two directions and, in the second press nip N2, substantially in one direction.

In Fig. 1 , the web W is picked up from a wire 9 of a former section by means of a pick-up roll 15 and transferred as a closed draw on support of the first press felt 10 to the first press nip Nl . After the first press nip Nl, the web W is separated from the first press felt 10 by means of a felt suction roll 14 situated inside the second press felt loop 11. After that, the web is picked up from the second press felt 11 by means of a first transfer suction roll 25 situated inside the upper press felt loop 20 of the second press nip N2 and transferred as a closed draw on support of the third press felt 20 to the second press nip N2. After the second press nip N2, the web W is picked up from the transfer belt 21 by means of a second transfer suction roll 31 situated inside a drying wire loop 30 and transferred as a closed draw on support of the drying wire 30 onto a first drying cylinder 32 of a dryer section applying single- wire draw and further onto a first reversing suction roll 33.

Fig. 2 is a schematic side view of a press with one nip, which comprises the second press nip of the press with two nips shown in Fig. 1. The web W is thus picked up from a wire 9 by means of a pick-up roll 15 and transferred to a first nip Nl, which is formed between an upper shoe roll 22 and a lower recessed-faced backing roll 24. Transfer of the web W from the press section to a dryer section takes place in a manner corresponding to that of Fig. 1. A short transfer belt loop 21 serves as a lower press fabric in the second press nip N2 of the press section illustrated in Fig. 1 and in the press nip Nl of the press illustrated in Fig. 2, all rolls 24, 26, 26', 27 and 28 of said transfer belt loop being supported on frame structures of the press by means of support equipment situated above the floor level LT of the machine hall. Thus, the transfer belt loop 21 runs at least for the most part above the floor level of the machine hall.

Fig. 3 is a schematic side view of the press nip Nl, N2 provided with the short lower transfer belt loop 21, shown in Figs. 1 and 2, in an operating position. The frame structures associated with the backing roll 24 of the press nip Nl , N2 and with the rolls 26, 26', 27, 28 of the transfer belt loop 21 are formed of a side frame 51,52,53 of the tending side, of a corresponding side frame of the driving side and of horizontal beams 54 connecting the side frames. The side frame of the tending side shown in the figure comprises two vertical beams 51,52 spaced from each other in the machine direction, which vertical beams are connected by means of a horizontal beam 53. The horizontal beam 53 of the side frame on the tending side is additionally connected to a horizontal beam of the side frame on the driving side by means of two transverse horizontal beams 54 spaced from each other in the machine direction. A bearing housing 42 of the lower backing roll 24 on the tending side rests on the horizontal beam 53 of the side frame of the tending side and a bearing housing of the backing roll 24 on the driving side rests, in a similar way, on the horizontal beam of the side frame of the driving side. The bearing housings 41, 42 of the upper shoe roll 22 and the lower backing roll 24 are coupled to each other by means of coupling devices, for example, tension bars 43, which receive the compres- sion load applied to the nip N1,N2. The vertical beams 51,52 of the side frame on the tending side additionally include intermediate pieces 61, which can be opened for the time of changing the transfer belt loop 21, after which they can be closed again. A tension roll 28 of the transfer belt loop 21 is supported at its bearing housings by means of a lever arm 71 through a pivot point 72 on one vertical beam 52 of the side frames and the lever arm 71 is supported by means of a loading device 73, for example, a hydraulic cylinder-piston structure on the horizontal beam 53 of the side frames. In the operating position, the nip N1,N2 is closed, the upper guide rolls 26' of the transfer belt loop 21 are in their upper position and the tension roll 28 of the transfer belt 21 is in its lower position, that is, in its tension position.

Fig. 4 is a schematic side view of the press of Fig. 3 in the change position of the transfer belt 21. The press nip N1,N2 is open, the upper guide rolls 26' of the transfer belt loop 21 are in their lower position, the tension roll 28 of the transfer belt loop 21 is in its upper position, i.e. in its rest position, a doctor 81 has been separated from the transfer belt 21, and the intermediate pieces 61 of the vertical beams 51 ,52 of the side frame on the tending side have been removed, in which connection openings 62 are formed in the vertical beams 51,52 of the side frame of the tending side, through which openings replacement of the transfer belt loop 21 can be performed. Moreover, a possible placement of guide members 102 of a change device described in connection with Fig. 5 has been drawn in the figure.

Fig. 5 is a schematic cross-machine direction view of an arrangement of changing the transfer belt loop 21, which arrangement is suitable for the situation of Fig. 4. In this arrangement, the horizontal beams 54 extending in the cross-machine direction and connecting the side frames on the tending side HP and the driving side KP are cantilever beams, which project on the driving side KP from vertical beams 51k of the side frame of the driving side of the press and are supported by means of a support member 90 on the floor structures of the machine hall. The figure also shows drive means 91 situated on the driving side KP. The intermediate pieces 61 of the vertical beams 51,52 of the side frame on the tending side HP are first removed by means of jacks, after which the lower backing roll 24 and the associated part of the side frame of the tending side HP above the openings 62 are lowered so as to be supported by said cantilever beams 54. The old transfer belt 21 can be removed, for example, by cutting it off and dropping it down into the basement spaces beneath the machine hall, after which the change device 100 is brought to the tending side HP at the press nip N1,N2, around which change device a new transfer belt 21 has been loaded. The change device 100 is formed of a carriage 101 which is provided with wheels and from which the guide members 102 disposed in a geometric form determined by the rolls 26, 26', 27, 28 of the transfer belt loop 21 project, the new transfer belt loop 21 having been placed around said guide members.

The new transfer belt loop 21 can be transferred to its place in the press by moving the change device 100 to such a position that the outer ends of the guide members 102 are placed on a level with the tending-side HP ends of the rolls 26, 26', 27,28 of the transfer belt loop 21, for example, to the points shown in Fig. 4, and attaching grip members provided with pulling ropes to the edge of the transfer belt 21, whereby the new transfer belt loop 21 can be pulled from the driving side KP by hand by means of the ropes to its place around the rolls 26, 26 ' ,27, 28. Here, initial guidance may be needed from the tending side HP in order that the edge of the transfer belt loop 21 shall be brought around the ends of the rolls.

A second alternative for transferring the new transfer belt 21 to its place is to push the new transfer belt loop 21 on support of the guide members 102 of the change device 100 to its position around the rolls 26, 26' , 27, 28 of the transfer belt loop 21, after which the driving-side KP edge of the transfer belt loop 21 is gripped by means of grip members and held when the change device 100 and the guide members 102 along with it are pulled out of the press.

In accordance with a third alternative, the guide members 102 have a telescopic structure, in which connection the transfer belt 21 is transferred by means of the change device 100 first close to the tending-side HP ends of the rolls 26, 26', 27, 28, after which the telescopes of the guide members 102 are pushed out. In the situation in which the transfer belt loop 21 is attached to the outer ends of the telescopes, the transfer belt loop 21 moves around the rolls 26, 26 ',27, 28 of the transfer belt loop 21 when the telescopes are being pushed out. Otherwise it may be pulled to its place from the driving side KP along the pushed-out telescopic tubes of the guide members 102 by means of grip members provided with pulling ropes and attached to the edge of the transfer belt loop 21. The latter two alternatives require that in the press there are suitable free spaces in which the guide members 102 and the telescopic tubes projecting from them can move.

Fig. 6 shows another alternative for changing the transfer belt loop 21. In this alternative, a projecting beam 130 is used which is secured from the tending side HP to the bearing housing 42 of the lower backing roll 24 or to the side frame of the tending side HP associated with the lower backing roll 24. In this embodiment, the cross-machine direction horizontal beams 54, which connect the side frames of the tending and driving sides of the machine, need not be cantilevered. After the old transfer belt 21 has been removed, for instance, by cutting and dropping it into the basement spaces beneath the machine hall, the projecting beam 130 is secured, for example, to the bearing housing 42 of the backing roll 24, after which the new transfer belt loop 21 is passed around the projecting beam 130. After that, for example, a hook 131 of a crane, is attached to the outer end of the projecting beam 130, so that the crane may support the backing roll 24 and its frame structures by means of the projecting beam 130. After the intermediate pieces 61 in the vertical beams 51,52 of the side frame on the tending side have been removed, the edge of the transfer belt loop 21 is placed onto the ends of the rolls 24, 26, 26' , 27,28 of the tending side HP, from which it is pulled in the manner described above from the driving side KP to its place by means of grip members attached to the edge of the transfer belt loop 21 and the ropes associated with the grip members.

In the situation of Fig. 6, a framework formed of guide members 102 similar to the one used in the change device 100 shown in Fig. 5 can also be fixedly attached to the projecting beam 130, which framework enables the transfer belt loop 21 to be placed in a geometric form determined by the rolls 24,26, 26', 27, 28 associated with the transfer belt loop 21. Pulling of the transfer belt loop 21 from the framework to its place in the press is thereby facilitated.

The projecting beam 130 and the framework formed of the guide members 102 can also be composed of separate parts such that the framework is not fixedly attached to the projecting beam 130. In that connection, the guide members 102 are fixed to the middle part of the framework in which there is an opening arranged to correspond to the cross section of the projecting beam 130, through which opening the framework can be pushed onto the projecting beam 130. The framework can thus be moved on the projecting beam 130, in which connection the framework and the transfer belt loop 21 around it can be pushed at least partly inside the machine.

The guide members 102 of the framework fixedly attached to the projecting beam 130 and those of the unfixed framework may also comprise the above-mentioned telescopic structure.

Fig. 7 shows a compact press with three nips, provided with a centre roll 214 and a transfer belt 211 running around it, in which press the method of changing the transfer belt 211 according to the invention can be applied. The first nip Nl is a roll nip which is formed between a lower recessed-faced press roll 203 and an upper press suction roll 202. The second nip N2 is also a roll nip and it is formed between said press suction roll 202 and the centre roll 214. The third nip N3 is an extended nip and it is formed between said centre roll 214 and an upper shoe roll 212. In the first nip Nl, water is removed from the web W in two directions and in the second N2 and the third N3 nip substantially in one direction.

In Fig. 7, the web W is picked up from a wire 9 of a former section by means of a pick-up roll 215 and transferred as a closed draw on support of a pick-up felt 200 to the first press nip Nl, in which water is removed from the web W into the pick-up felt 200 serving as an upper fabric and into a lower press felt 201. After the first press nip Nl, the web W follows the pick-up felt 200 aided by a vacuum acting through the perforation of the press suction roll 202 in a first suction zone 202a and is transferred on its surface into the second press nip N2, in which the pick-up felt 200 functions as a water-receiving press fabric. In the area of the second press nip N2, the press suction roll 202 has a second suction zone 202b, after which the web W follows the surface of the transfer belt 211 running around the centre roll 214 of the press, the surface of said transfer belt 211 having such properties of adhesion to the web W that the web W is separated after the second press nip N2 from the surface of the pick-up felt 200 and follows the surface of the transfer belt 211, on which the web W is transferred to the third press nip N3. In the third press nip N3, which is an extended nip, water is removed from the web W into a press felt 210 serving as an upper fabric. After the third press nip N3, the web W follows the outer surface of the transfer belt 211, which is more adhesive to the web W than the surface of the press felt 210. After the third press nip N3, the web W is picked up from the transfer belt 211 by means of a transfer suction roll 31 situated inside a drying wire loop 30 and transferred as a closed draw on support of the drying wire 30 onto a first drying cylinder 32 of a dryer section applying single-wire draw.

Fig. 8 shows a variant of the compact press with three nips shown in Fig. 7. In the embodiment shown in Fig. 8, the second press nip N2 is formed between the centre roll 214 and a separate recessed-face press roll 204. The press section roll 202 forming the first press nip Nl comprises one suction zone 202a. In other respects, the embodiment shown in Fig. 8 corresponds to the embodiment shown in Fig. 7.

Fig. 9 is a schematic side view of the press shown in Fig. 7 in an operating position. The centre roll 214 is supported on side frames 255 of the tending side and the driving side, rolls 215,216,217 associated with the transfer belt loop 211 running around the centre roll 214 being also supported on said side frames. The lower parts of the side frames are formed of a bifurcated portion, the branches of which are supported on the floor structures of the machine hall. Both branches are provided with openable and closable intermediate pieces 261. A horizontal beam 254 extend- ing in the cross-machine direction is also connected with the side frame 255. In the operating position, the nips N1,N2,N3 are closed and the tension roll 217 of the transfer belt loop 211 is in its lower position, i.e. in its tension position. The movement of the tension roll 217 is taken care of by means of a hydraulic piston- cylinder construction 273 fixed to the side frame 255. The roll 216 functions as a guide roll of the transfer belt loop 211. Fig. 10 shows the press of Fig. 9 in the change position of the transfer belt 211. The nips N1 ,N2,N3 are open, the tension roll 217 of the transfer belt loop 211 is in its upper position and the intermediate pieces 261 of the side frame 255 on the tending side have been removed, in which connection openings 262 are formed in the branches, through which openings the transfer belt 211 can be passed to its place.

Fig. 11 is a schematic cross-machine direction view of an arrangement of changing the transfer belt loop 211, which arrangement is suitable for the situation of Fig. 10. The figure shows that the cross-machine direction horizontal beam 254 is a canti- lever beam which projects on the driving side KP from the driving-side side frame of the press and is supported by means of a support member 290 on the floor structures. The figure also shows drive means 291 situated on the driving side KP. The intermediate pieces 261 in the branches of the side frame 255 on the tending side are first removed by means of jacks, after which the centre roll 214 and the frame structures of the tending side associated therewith are lowered so as to be supported by said cantilever beam 254. After the old transfer belt 211 has been removed, the change device 100 with a new transfer belt 211 loaded around it is brought to the tending side HP. The change device 100 corresponds to the change device 100 shown in Fig. 5 and the change of the transfer belt 211 takes place in the manner explained in connection with Fig. 5.

Fig. 12 is a schematic cross-machine direction view of another arrangement of changing the transfer belt loop, which arrangement is suitable for the situation of Fig. 10. Here, the projecting beam 130 shown in Fig. 6 is used, and the change of the transfer belt 211 takes place in the manner depicted in connection with Fig. 6.

Fig. 13 shows a further variant of the compact press with three nips shown in Fig. 7. Of rolls 214,215—218 of the transfer belt loop 211, a guide roll 216 is situated outside the transfer belt loop 211. Said guide roll 216 outside the transfer belt loop 211 is supported on the floor structures of the machine hall by means of a separate auxiliary side frame 256, which is connected by means of an openable and closable loading joint or intermediate piece 261 to the side frame 255 proper on which the other rolls 214,215,217,218 of the transfer belt loop 211 are supported. In this embodiment, the side frame 255 proper is additionally connected on the tending side HP by means of the openable and closable loading joint or intermediate piece 261 to the side frame structures of the roll 212 above the third nip N3. For this reason, said upper side frame structures are also supported by means of a cross-machine direction cantilever beam 301 during the replacement of the transfer belt 211.

Fig. 14 is a schematic end view of a framework used in changing the transfer belt. The framework is formed here of guide members 102, which are supported at their ends by a support structure formed of support members 103 and by a curve-shaped guide plate 104. The form of the framework substantially corresponds to the geometric form of the transfer belt loop 211 in its position of operation. The support members 103 are here attached to the projecting beam 130. The framework of the figure is particularly suitable for changing the transfer belt 211 of the press shown in Fig. 13. A guide member 106 aids in guiding the transfer belt 211 into connection with the roll 216 situated outside the transfer belt loop 211.

The framework shown in Fig. 14 is used such that the transfer belt loop 211 is placed on the guide members 102 of the framework fixedly attached to the projecting beam 130. After that, the projecting beam 130, the framework around it and the transfer belt 211 around the framework are moved close to the press on the tending side HP, after which the projecting beam 130 is secured to the side frame of the tending side. The ends of the guide members 102 will then be on a level with the tending-side HP ends of the rolls 214,215—218 of the transfer belt and, when the side frame of the tending side HP is supported by the projecting beam 130 and the intermediate pieces 261 have been removed from the side frame of the tending side HP, the transfer belt 211 can be pulled to its place of operation in the manner described in connection with Fig. 6.

As stated above in connection with Fig. 6, the framework can also be accomplished such that the support members 103 of the framework are fixed to the middle part of the framework, in which there is an opening arranged to correspond to the shape of the cross section of the projecting beam 130, through which opening the framework can be pushed onto the projecting beam 130. In that connection, the framework can be moved on the projecting beam 130. The guide members 102 of the framework may also have the telescopic structure described above.

In the figures described above, the short transfer belt loop is a lower fabric of the press, but the method according to the invention can, of course, be also applied in a situation where the transfer belt loop is an upper fabric.

In the figures described above, the method according to the invention for changing a transfer belt loop in a paper or board machine by means of a change device or a projecting beam projecting to the tending side, has been described only in connection with a press section formed of separate nips and a compact press section provided with a centre roll, but the method is, of course, also suitable for changing other transfer belt loops.

In connection with the figures, only the frame structures supporting the rolls of the transfer belt loop have been depicted. The frame structures supporting the rolls of other fabric loops and the methods of changing the fabrics may be based on any known arrangements.

The claims are presented in the following and the details of the invention may vary within the inventive idea defined by said claims and differ from the disclosure given above by way of example only.

Claims

1. A method for changing a transfer belt (21 ;211) in a paper or board machine in which rolls (24,26' ,27,28;214— 217) of the transfer belt loop (21;211) are supported by a frame structure which comprises a side frame on a tending side (HP), which side frame includes intermediate pieces (61 ; 261) that can be opened and closed, and a side frame on a driving side (KP), which side frames have been interconnected by means of transverse beams (54;254) which project from the side frame of the driving side (KP), the outer ends of said projections being coupled to floor structures of the machine hall by means of support members (90; 290), in which method first a nip or nips (N1 ,N2,N3) is/are opened through which the transfer belt loop (21;211) runs, at least a tension roll (28; 217) of the transfer belt loop (21;211) is moved to a change position, the old transfer belt loop (21;211) is removed, and the intermediate pieces (61;261) in the side frame of the tending side (HP) are opened, in which connection the side frame of the tending side (HP) rests in cantilever support on the transverse beams (54; 254), characterized in that the method further comprises the following steps:

— a new transfer belt loop (21;211) is brought to the tending side (HP) of the machine by means of a change device (100) which is formed of a movable carriage (101), to which guide members (102) have been attached, which guide members have been disposed in a geometric form substantially determined by the rolls (26,26', 27,28;214— 217) of the transfer belt loop (21;211), and around which guide members (102) the new transfer belt loop (21;211) has been placed, — the new transfer belt loop (21;211) is transferred to its position of operation around the rolls (26,26', 27,28;214— 217) of the transfer belt loop (21;211) through openings (62; 262) which remain in the side frame of the tending side (HP) after the intermediate pieces (61; 261) have been opened, and the intermediate pieces (61;261) are closed.

2. A method according to claim 1, characterized in that grip members provided with pulling members are attached to the edge of the transfer belt loop (21;211), after which the transfer belt loop (21 ;211) is pulled by means of the pulling members from the driving side (KP) of the machine from the guide members (102) situated on the tending side (HP) of the machine so as to be around the rolls (26,26', 27, 28; 214—217) of the transfer belt loop (21;211).

3. A method according to claim 1 , characterized in that the change device (100) and the transfer belt loop (21;211) disposed around it are pushed from the tending side (HP) into the machine, in which connection the guide members (102) projecting from the change device (100) are pushed inside the machine and the transfer belt loop (21 ; 211 ) is positioned around its rolls (26 , 26 ' , 27 , 28 ; 214—217), after which the driving-side edge of the transfer belt loop (21;211) is gripped by means of grip members, the change device (100) is pulled out of the machine, and the transfer belt loop (21;211) remains resting on its rolls (21,26',27,28;214— 217).

4. A method according to claim 1 , characterized in that the guide members (102) attached to the change device (100) have a telescopic structure, in which connection the transfer belt loop (21;211) is pushed into the machine on support of the guide members (102) with a telescopic construction while the carriage (101) remains in place beside the machine.

5. A method for changing a transfer belt loop (21;211) in a paper or board machine in which rolls (24,26', 27,28;214— 217) of the transfer belt loop (21;211) are supported by a frame structure which comprises a side frame on a tending side (HP) , which side frame includes intermediate pieces (61; 261) that can be opened and closed, and a side frame on a driving side (KP), which side frames have been interconnected by means of transverse beams (54; 254), in which method first a nip or nips (N1,N2,N3) is/are opened through which the transfer belt loop (21;211) runs, at least a tension roll (28;217) of the transfer belt loop (21;211) is moved to a change position, and the old transfer belt loop (21;211) is removed from the machine, characterized in that the method further comprises the following steps: — a projecting beam (130) projecting towards the tending side (HP) is secured to the side frame of the tending side (HP), — a new transfer belt loop (21;211) is passed around the projecting beam (130), the outer end of the projecting beam (130) is coupled to a hoisting device, by means of which the projecting beam (130) and thereby the side frame of the tending side (HP) are supported, — the intermediate pieces (61; 261) in the side frame of the tending side are opened,

— the new transfer belt loop (21;211) is transferred to its position around the rolls (26,26', 27,28;214-217),

— the intermediate pieces (61;261) are closed again in the side frame of the tending side (HP),

— the side frame of the tending side (HP) is lowered so as to be supported on the floor, and

— the projecting beam (130) is removed from the side frame of the tending side (HP).

6. A method according to claim 5, characterized in that the projecting beam (130) is secured to the side frame of the tending side (HP), around which projecting beam there is a framework fixedly attached to the projecting beam (130), the new transfer belt loop (21;211) having been placed around guide members (102) of the framework in a geometric form substantially determined by the rolls (26,26' ,27,28;214— 217) of the transfer belt loop (21;211), after which grip members provided with pulling members are attached to the edge of the transfer belt loop (21 ;211), by means of which grip members the transfer belt loop (21;211) is pulled from the driving side (KP) of the machine from the guide members (102) of the framework so as to be around its rolls (26,26' , 27,28;214-217).

7. A method according to claim 5, characterized in that the projecting beam (130) and a framework situated around the projecting beam (130) and sliding on the projecting beam (130) are secured to the side frame of the tending side (HP), the new transfer belt loop (21;211) having been placed around guide members (102) of the framework in a geometric form substantially determined by the rolls (26, 26', 27, 28;214— 217) of the transfer belt loop (21;211), after which the framework and the transfer belt loop (21;211) placed around it are pushed into the machine, in which connection the guide members (102) of the framework are pushed inside the machine and the transfer belt loop (21 ;211) is positioned around its rolls (26, 26', 27,28; 214—217), after which the driving-side edge of the transfer belt loop (21;211) is gripped by means of grip members, the framework is pulled out of the machine, and the transfer belt loop (21 ; 211) remains resting on its rolls (26,26 ' ,27,28 ;214— 217).

8. A method according to claim 6, characterized in that the guide members (102) attached to the framework have a telescopic structure, in which connection the transfer belt loop (21;211) is pushed into the machine on support of the guide members (102) with a telescopic construction while the framework remains in place on the projecting beam (130).