SEAL CONSTRUCTION FOR A SUCTION ROLL IN A PAPER MACHINE

Abstract: The invention concerns a seal construction for a suction roll in a paper machine. The seal construction (10) comprises a substantially U-section holder (12) open towards the inner face (3) of the roll mantle, a seal, which is mounted in the holder, which is placed in the axial direction of the roll, and which consists of a frame part (13) of the seal fitted in the holder (12) and of a wear part (11), which is fixed to the frame part and which is placed against the inner face (3) of the roll mantle, and which seal construction also comprises loading means, such as a loading hose (15) or equivalent, by whose means the seal can be shifted in the holder (12) against the inner face (3) of the roll mantle. According to the invention, in the interior of the frame part (13) of the seal, an inner loading member (16) has been arranged, by whose means the frame part of the seal can be locked in contact with the holder (12) so as to position the wear part (11) of the seal in the desired position in relation to the inner face (3) of the roll mantle.

Description: Seal construction for a suction roll in a paper machine The invention concerns a seal construction for a suction roll in a paper machine, comprising a substantially U-section holder open towards the inner face of the roll mantle, a seal, which is mounted in the holder, which is placed in the axial direction of the roll, and which consists of a frame part of the seal fitted in the holder and of a wear part which is fixed to the frame part and which is placed against the inner face of the roll mantle, and also comprising loading means, such as a loading hose or equivalent, by whose means the seal can be shifted in the holder against the inner face of the roll mantle. In suction rolls in paper machines, the wear of seals has constituted a rather signifi¬ cant problem. The problem has been emphasized in particular because it has been a general aim to obtain longer servicing intervals. The seals in a suction roll divide the interior of the roll mantle appropriately into vacuum chambers, and by means of a vacuum passed into said vacuum chambers a suction effect is applied through the holes, which have been formed into the roll mantle, to the paper web placed on the outer face of die roll mantle in order that the web should remain on the face of the roll mantle in the desired way and over the desired distance. The seals are loaded against the inner face of the roll mantle. In an attempt to obtain an efficient and well sealed suction roll, in earlier solutions, d e seals in the suction roll were pressed, for example by means of compressed air, against the inner face of the roll mantle. The compression force was maintained constantly, which resulted in quite rapid wear of me seals. A high compression force required water lubrication of the seals with abundant quantities of water. Further, owing to the high compression force, the consumption of power was considerable. In view of eliminating tiiis problem of wear, in the applicant's earlier Finnish Patent Application No. 934909, the seals were not loaded constantly against the inner face of the roll mantle of the suction roll, but the seals were provided with locking means so that initially the seal was pressed against the inner face of the roll mantle, and after a vacuum had been generated in the vacuum chamber defined by the seals, the seal was locked in its holder. Then it was possible to eliminate the load with which the seals were pressed against d e inner face of the roll mantle. The wear of die seals could be reduced substantially, compared with the prior art, and it was often even possible to eliminate die water lubrication of the seals. This earlier solution of me applicant, however, involved the quite substantial problem tiiat, in order that the desired sealing effect could be provided, the manufacturing tolerances of the seal construction were very little. Owing to these little tolerances, a consequence could be sticking of the seal in its position, as a result of which the desired sealing effect was not produced. It was a second quite remarkable problem or drawback of said solution that the seal construction with the holders included in it was of rather exceptional construction, so that, if said solution was to be applied in a suction roll, the whole seal construction with all of its components had to be changed. The object of the present invention is to provide a novel and improved seal construc¬ tion for a suction roll in a paper machine, by means of which seal construction the problems related to the earlier constructions are eliminated and solved. In view of achieving the objectives of the invention, the seal construction in accordance with the invention is mainly characterized in that, in the interior of the frame part of the seal, an inner loading member has been arranged, by whose means the frame part of the seal can be locked in contact with the holder so as to position the wear part of the seal in the desired position in relation to the inner face of the roll mantle. By means of the present invention, considerable advantages are obtained over the prior-art solutions, and of these advantages should be mentioned the simplicity of the construction and, as a result of the simplicity, reliability in operation, as well as the fact that, when an existing seal construction is replaced, in many cases the holder of the existing seal can be retained unchanged without having to replace it. Further, as a result of the invention, a non-rubbing and, therefore, substantially non-wearing seal construction has been provided, and the consumption of power caused by said seal construction is very low, compared with earlier solutions. The further advan¬ tages and characteristics of the invention come out from the following detailed description of the invention. In the following, the invention will be described by way of example with reference to the figures in the accompanying drawing. Figure 1 is a fully schematic illustration of a suction roll in a paper machine, in which roll a seal construction in accordance with the invention is used. Figure 2 is a more detailed sectional view of a first embodiment in accordance with the invention of the seal construction for a suction roll. Figure 3 is an illustration corresponding to Fig. 2 of a second embodiment of the seal construction in accordance with the invention. Fig. 1 shows conventional operation of a suction roll in a paper machine, to which the seal construction in accordance with the invention can be applied. The paper web W is passed through the nip N j between the suction roll 1 and the backup roll 5 onto the face of the roll mantle 2 of the suction roll 1 and along the face of the roll mantle 2 into the nip N 2 between the suction roll 1 and the second backup roll 6 and from there further to further treatment. In the interior of the suction roll 1 , there is a suction box 4, to which seal constructions 10 have been fitted, whose seals form vacuum chambers S j and S 2 between them. According to Fig. 1, the seals rest against the inner face 3 of the roll mantle 2. By means of the vacuums present in the vacuum chambers Si ,S 2 , the web W is kept in the desired way against the outer face of the roll mantle 2 and/or water is sucked out of the web W into the vacuum chambers S j ^. The arrangement described herein involves nothing in itself novel, but the arrangement is as such known and included in the prior art. On the contrary, the novelty is related to the seal constructions 10 shown in Fig. 1, which are illus¬ trated in more detail in Figs. 2 and 3 in the drawing. In Fig. 2 a first embodiment of the seal construction in accordance with the inven¬ tion is denoted generally with the reference numeral 10. The seal construction 10 comprises the seal itself, whose wear part 11 is mounted in a U-section holder 12, which is open towards the inner face 3 of the roll mantle. In the embodiment shown in Fig. 2 the wear part 11 is fixed to a frame part 13 of the seal, which is made of an elastic material. The joint between the wear part 11 and the frame part 13 of the seal is denoted with the reference numeral 14, and according to Fig. 2, said joint 14 is a dovetail joint or equivalent. The measure of the wear part 11 of the seal is smaller than the inside measure of the holder 12, so that the wear part 11 can move readily in the holder 12, but, on the contrary, the frame part 13 of the seal is shaped so that said frame part 13 is fitted in the holder 12 with a slight pinching. The support point between the frame part 13 of the seal and the holder 12 at which the pinching occurs is denoted with the reference numerals 17. Under the frame part 13 of the seal, on the bottom of the U-section holder 12, a loading hose 15 or an equivalent loading member has been fitted, by whose means the wear part 11 of the seal can be pressed against the inner face 3 of the roll mantle. Such a mode of loading is common in seal constructions in suction rolls, and it results in the drawbacks that were described above in relation to the description of the prior art. It is one of the most important ones of these drawbacks that the constant loading of the wear part 11 against the inner face 3 of the roll mantle abrades the seal intensively and rapidly and, as a result of this, reduces the service life of the wear part 11. Owing to the constant loading, in normal cases, the seal construction must also be provided with efficient water lubrication. In the present invention, in the embodiment shown in Fig. 2, in the interior of the frame part 13 of the seal, which is made of an elastic material, a loading hose 16 or an equivalent loading member has been fitted, which can be subjected to a pressure and because of which the wear problem of the seal is substantially solved. When the loading hose 16 in the interior of the frame part 13 of the seal is pressurized, the elastic frame part 13 yields, whereby the wear projections 18 formed on the side faces of the frame part 13 of the seal are pressed against the walls of the holder 12 and lock the frame part 13 and the wear part 11 of the seal in their positions. When the wear part 11 of the seal is locked in its position, as a matter of fact the procedure is such that, when the inside loading hose 16 is pressurized, the wear projections 18 "revolve" around the support points 17, whereby the elastic frame part 13 of the seal is shaped so that the wear part 11 of the seal is shifted slightly apart from the inner face 3 of the roll mantle. In this connection, when the wear projections 18 grasp the walls of the holder 12, the wear part 11 of the seal is locked in its position so that it does not rub against the inner face 3 of the roll mantle. Then, the seal is, of course, not worn. The operation described above, i.e. shifting of the wear part 11 of the seal apart from the inner face 3 of the roll mantle and locking of said wear part in its position, can be achieved simply so that the inner loading hose 16 in the frame part 13 of the seal is reinforced by means of fabrics in a suitable way, whereby the pres- sure in the hose produces a movement and a force exactly in the desired direction. Fig. 3 shows a second embodiment of the seal construction in accordance with the invention. In Fig. 3, the seal construction is denoted with the reference numeral 10a and, as simplified, the seal construction 10a comprises a wear part lla of the seal, which has been fitted as mobile in the holder 12a and which can be shifted against the inner face 3 of the roll mantle 2. The wear part lla and the holder 12a of the seal can be exactly identical with those shown in the embodiment of Fig. 2. As is the case in Fig. 2, so also in the embodiment of Fig. 3, a loading hose 15a is fitted on the bottom of the holder 12a, by means of which loading hose the wear part lla of the seal can be loaded against the inner face 3 of the roll mantle by means of the frame part of the seal. Whereas in Fig. 2 the frame part of the seal consisted of a unified single piece made of an elastic material, in the embodiment of Fig. 3 the frame part 13' consists of a first support plate 13a attached to the wear part l la of the seal by means of a suitable joint 14a, of a second support plate 17a fitted on the loading hose 15a, and of an articulation mechanism fitted between these support plates 13a, 17a. In the embodiment shown, the articulation mechanism consists of a quadrangle with articulated joints, in which articulated joints 18a, 19a have been mounted on the support plates 13a, 17a, with which joints 18a, 19a the articulation rods 21a have been linked. On the other hand, the articulation rods 21a coming from the first and the second support plate 13a, 17a are again interconnected by means of the articulated joints 20a. Said articulated joints 20a which interconnect the articula- tion rods 21a are supported displaceably against the walls of the holder 12a. Further, inside the articulated quadrangle, an inner loading hose 16a is fitted. The system operates so that, by pressurizing the loading hose 15a, the wear part l la of the seal is run into contact with the inner face 3 of the roll mantle. After this the inner loading hose 16a is pressurized, whereby the articulated joints 20a that interconnect the articulation rods 21a are pressed against the walls of the holder 12a and lock the wear part lla of the seal in its position. At the same time as the articulated joints 20a are locked against the walls of the holder 12a, owing to the articulation mechanism, the wear part l la of the seal is pulled apart from the inner face 3 of the roll mantle in a way similar to the embodiment shown in Fig. 2. Thus, the wear part lla of the seal remains non-rubbing in its regulated position, in which case, if necessary, the pressure can be discharged from the loading hose 15a. Also in the embodiment of Fig. 3, the desired function of the articulation mechanism can be achieved thereby that the inner loading hose 16a is reinforced appropriately by means of fabrics, whereby the movement and the force produced by the pressure in the hose can be made to be formed exactly in the desired direction. As a brief summary of the above, it can still be stated that, by means of the solution of the present invention, a seal is provided that does not rub against the roll mantle and that is substantially non- wearing, the power consumption caused by said seal being minimal compared with the prior-art solutions. Above, the invention has been described by way of example with reference to the figures in the accompanying drawing. The invention is, however, not confined to the exemplifying embodiments illustrated in the figures alone, but different embodiments of the invention may show variation within the scope of the inventive idea defined in the accompanying patent claims.

Claims: Claims 1. A seal construction for a suction roll in a paper machine, comprising a substan¬ tially U-section holder (12,12a) open towards the inner face (3) of the roll mantle, a seal, which is mounted in the holder, which is placed in the axial direction of the roll, and which consists of a frame part (13,13') of the seal fitted in the holder (12, 12a) and of a wear part (11,11a), which is fixed to the frame part and which is placed against the inner face (3) of the roll mantle, and also comprising loading means, such as a loading hose (15,15a) or equivalent, by whose means the seal can be shifted in the holder (12,12a) against the inner face (3) of the roll mantle, characterized in that, in the interior of the frame part (13,13') of the seal, an inner loading member (16,16a) has been arranged, by whose means the frame part of the seal can be locked in contact with the holder (12,12a) so as to position the wear part (11,1 la) of the seal in the desired position in relation to the inner face (3) of the roll mantle. 2. A seal construction as claimed in claim 1, characterized in that the frame part (13) of the seal is made of an elastic material, and that the inner loading member (16) has been fitted inside the material of the frame part so that the loading produced by the inner loading member (16) expands the frame part (13) of the seal against the walls of the holder (12) so as to lock the wear part (11) of the seal in its position. 3. A seal construction as claimed in claim 2, characterized in that the frame part (13) of the seal has been fitted in the holder (12) with a slight pinching. 4. A seal construction as claimed in claim 2 or 3, characterized in that, on the frame part (13) of the seal, support points (17) have been shaped which extend more widely than the rest of the frame part, said support points (17) being supported against the walls of the holder (12) with a slight pinching. 5. A seal construction as claimed in any of the claims 2 to 4, characterized in that, when the frame part (13) expands, the loading produced by the inner loading member (16) causes a movement of rotation in the frame part around the contact points between the support points (17) of the frame part and the walls of the holder (12), in which connection the wear part (11) of the seal is shifted away from the inner face (3) of the roll mantle when the seal is locked in its position. 6. A seal construction as claimed in claim 1, characterized in that the frame part (13') of the seal comprises an articulation mechanism, in which the articulation rods (21a) have been linked with each other and with the support plates (13a, 17a) placed under the wear part (l la) of the seal and on the loading hose (15a) fitted on the bottom of the holder (12a), an inner loading member (16a) being fitted inside said articulation mechanism. 7. A seal construction as claimed in claim 6, characterized in that the articulation rods (21a) of the articulation mechanism, which are linked with the first support plate (13a) placed below the wear part (l la), on one hand, and with the second support plate (17a) placed above the loading hose (15a), on the other hand, are interconnected by means of articulated joints (20a), which are supported against the walls of the holder (12a). 8. A seal construction as claimed in claim 6 or 7, characterized in that the loading produced by means of the inner loading member (16a) of the articulation mechanism makes the articulated joints (20a) that interconnect the articulation rods (21a) to be pressed against the walls of the holder (12a) and lock the seal in its position. 9. A seal construction as claimed in any of the claims 6 to 8, characterized in that, when the seal is locked in its position by means of the inner loading member (16a) in the articulation mechanism, the wear part (l la) of the seal is fitted to be shifted apart from the inner face (3) of the roll mantle. 10. A seal construction as claimed in any of the claims 6 to 9, characterized in that the articulation mechanism is a quadrangle provided with articulated joints.

Inventors: KARTTUNEN HEIKKI, KARTTUNEN, HEIKKI
Applicants: VALMET CORP, VALMET CORPORATION
Application year: 1996
Main classification: D21F3
IPC codes: D21F3