DEVICE IN A CANTILEVERED FRAME PART OF THE PRESS SECTION AND/OR WIRE PART OF A PAPER MACHINE

Abstract: Method and devices in a cantilevered frame part of the press section and/or wire part of a paper machine, wherein the cantilever beam (10) attached between the side frames (11,12) is pre-tensioned by pressing its pro­ jection part (10a) downwards with a certain force (F). The pre-tensioning is produced by means of power means (23;40;50), prefer­ ably a hydraulic power unit, which produces a downwardly directed pre-tensioning force (F) in the projection part (10a) of the cantilever beam (10). The pre-tensioning is released after the replacement of press fabrics or equivalent has been carried out and the side frame (11) at the service side has been locked or can be locked.

Description: The invention concerns a device in a cantilevered frame part of a press section and/or wire section of a paper machine located in a machine hall, in which a cantilevered beam extends between side frames, said cantilevered beam including a projecting part. In prior art (see DE-A-2 943 974 for example), such frame parts of a paper machine are known in which there are cantilevered transverse beams in the transverse direction of the paper machine and arranged in such a way that at the service side of the paper machine there are intermediate pieces openable by means of power units, through which said opened pieces the closed fabric loops of the paper machine can be pushed to around the rolls and cross beams in connection with replacement of the fabrics. In the way known in another prior art, the opposite projection part of the cantilever beams, opposite in relation to said openable intermediate pieces, i.e. the beam end at the service side of the paper machine, is fixed to the ceiling, wall or floor of the paper machine hall, most commonly by means of massive screws to a projection part on the wall of the paper machine hall. The function of said fastening is to support the cantilever beam when said intermediate pieces are opened. This prior-art fastening involves certain drawbacks, which come from the fact that the fastening is all the time under tension. This is why, oscillations are spread from the paper machine frame through said fastening to the wall constructions of the paper machine hall, which said oscillations increase the noise level in the paper machine hall, besides other drawbacks. Another drawback of said tensioning fastening is that the high forces used therein may cause deformations of the long frame beams, which may be even highly detrimental, e.g., in view of the parallel alignment of the axles of the various rolls. The object of the present invention is to provide a novel device by means of which it is possible to avoid the drawbacks discussed above. In view of achieving this object and those that will come out later, the device of the invention is mainly characterised by the features defined in the characterising clause of appended claim 1. Preferred embodiments of the invention are stated in the appended sub-claims. According to the invention, the pre-tensioning of the cantilever beam can be released wren the side frames at the service side have been fixed and when the machine is in normal operation; said pre-tensioning can be switched on by means of the device in accordance with the invention, to operate in the connection when the intermediate pieces in the side frames at the service side have been opened, so that the sag of the cantilever beam should not become disturbingly large. 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 A is a schematical transverse vertical sectional view that illustrates a prior-art fastening and pre-tensioning of the end of a cantilever beam in the frame part of a paper machine. Figure 1 shows a first embodiment of the invention. Figure 2 illustrates the invention and the pivot points and proportions of its lever mechanism. Figure 3 shows the same as Fig. 2, seen in the longitudinal direction of the cantilever beam from outside the beam. Figure 4 shows a second embodiment of the invention whereas Figure 5 shows a third embodiment. Fig. A illustrates a prior-art cantilevered frame of a paper machine, e.g. a frame of a press section. The frame comprises a transverse cantilever beam 10, in connection with which there are the side frames of the paper machine, whereof the service-side side frame 11 and the operation-side side frame 12 are shown schematically in Fig. A. In the way known in prior art, the projection part 10a of the cantilever beam 10 at the operation side is fixed to a projection part 17 on the wall 16 of the paper machine hall. This fixing is carried out through a hole 20 made through the end of the projection part 10a of the beam 10 by means of a draw bar 18. The draw bar 18 passes through a box bolster 19 mounted in the building in the machine direction, which said bolster rests against the plane bottom side of the projection part 17. The nuts 21 and 22 of the draw bar 18 are, as a rule, tightened permanently so that a suitable permanent support and pre-tensioning are obtained for the beam 10. In this state of tension, the draw bar 18 is subjected to a considerable tensile strain. The bar 18 and its nuts 21 and 22 are very robust, so that their opening is not rational, usually hardly even possible, e.g., upon replacement of a press felt. Fig. A shows the press roll 13 of the press section, which is mounted on the side frames 11 and 12 by the intermediate of its bearings and axle journals 13a. Moreover, Fig. A shows the loading means, such as loading levers and cylinders, of the press roll 13 schematically, said loading means being denoted with the reference numeral 14. In connection with the side frame 11 of the service side, there are openable intermediate pieces, of which the intermediate piece 15 is shown in Fig. A. After opening of the intermediate pieces 15 and of other intermediate pieces, through the space made free by the opening of said intermediate pieces, a closed loop of press fabric can be pushed to around the press rolls, guide rolls, and the cantilever beam 10, whereinafter the intermediate pieces 15 etc. are closed and the side frame 11 is locked. In connection with these replacement operations, as is known in prior art, the fastening 17,18,19,21,22 of the projection part 10a of the beam 10 is not opened, but the cantilever beam 10 has a certain pre-tension all the time, owing to the permanent force F, whose purpose is to reduce the sag of the end of the beam 10 placed at the proximity of the service-side side frame 11 and to make it easier to open the intermediate pieces 15. To begin with, the principle of a first embodiment of the device in accordance with the invention will be described mainly with reference to Fig. 2. Above the projection part 10a of the cantilever beam 10, a hydraulic cylinder 23 is attached, by means of whose piston rod 24 the point C is loaded to the left around the articulation point A of the angular arm 27. The lower arm 27b of the angular arm 27 is attached to the draw bar 30 at the point B. When the point B remains stationary and when the draw bar 30 is loaded by the tensile force F, the point A and, along with it, the whole projection part 10a of the cantilever beam 10 attempts to turn downwards, and the beam 10, being supported by the side frame 12, upwards. In this way, the necessary pre-tensioning of the beam 10 is produced, whose magnitude can be adjusted by means of the limiter screw 34. The necessary pre-tensioning force F can be set by altering the ratio of the dimensions S and M of the angular arm 27, while the size of the loading cylinder 23 and the loading pressure p can, if necessary, be kept invariable, e.g. S = 300 mm and M = 1000 mm. After the intermediate pieces 15 have been opened and the felts been replaced, the pretensioning of the beam 10 is released in accordance with the invention by removing the pressure out of the hydraulic cylinder 23 and by pivoting the angular arm 27 against the limiter 35 at the point E. The principle of operation and the construction of the embodiment of the invention shown in Fig. 1 are similar to that described above. As is shown in Fig. 1, the lower arm 27b of the angular arm 27 is attached to the draw bar 30 by means of the articulated joint 33. The draw bar 30 passes through a box bolster 31 mounted in the building in the machine direction. The draw bar 30 is fixed by means of nuts 32 in connection with the box bolster 31. In the other respects, the construction is similar to that shown in Fig. 2. Fig. 2 differs from Fig. 1 in the respect that at the upper end of the draw bar 30 there is a fork 37, which is attached to the lower part 27b of the angular arm 27 at the point B by means of an articulation shaft 33. Fig. 4 shows another embodiment of the invention, which differs from the above. According to Fig. 4, the piston rod 41 of a draw cylinder 40 is attached to the outer end of the projection part 10a of the cantilever beam 10 by means of brackets 47 and articulation pins 42. At its bottom end, the draw cylinder 40 is attached to a draw bar 44 by means of an articulation pin 43, said draw bar 44 passing through the box bolster 45 mounted in the building in the machine direction. The draw bar 44 transfers the lifting force to the box bolster 45 by means of a nut 46. The flange 48 at the top end of the box bolster 45 rests against the lower plane side of the projection part 17 on the wall 16. When a certain pressure p is introduced into the draw cylinder 40 out of a pressure source 39 shown schematically, the draw cylinder tends to become shorter and to pull the projection part 10a downwards, whereby, at a certain point of time, pretensioning can be provided in the cantilever beam 10. According to Fig. 5, a lifting cylinder 50 or jack is fixed onto the top side of the projection part 10a of the cantilever beam 10, the lifting part 51 of said lifting cylinder being fitted against the lower flange 55 of the box bolster 52 mounted in the building in the machine direction. The upper flange 53 of the box bolster 52 rests against the horizontal lower side of the projection part 17 on the wall 16. By increasing the length of the lifting cylinder 50, which is carried out by passing the pressure p from the pressure source 39 into the lifting cylinder 50, the pre-tension necessary in connection with the replacement of felt or equivalent can be provided in the cantilever beam 10a, which said pre-tension can also be released readily. It is an essential feature of the invention that the power units 23,40 and 50 have no pressure p and the cantilever beam is not pre-tensioned in connection with normal operation of the machine. When a felt or equivalent is replaced and the intermediate pieces of the side frame 11 are opened by means of cranes in themselves known, the pressure p is passed into the power units 23,40,50, which said pressure has been chosen such that, by means of a mechanism in accordance with the invention, a certain pre-tension of appropriate magnitude is always provided in the cantilever beam 10. This pre-tensioning is chosen so that the sag of the end of the cantilever beam 10 placed at the service-side side frame 11 does not become excessively large. As a rule, the pressure p in the power units 23,40,50 does not have to be regulated, but the magnitude of the pre-tensioning force F and the magnitude of the deflection of the projection part 10a of the beam 10 downwards are determined by mechanical devices, such as, in accordance with Figs. 1 and 2, by the limiter 34 provided at the end of the lower part 27b of the angular arm 27, said limiter 34 being, if necessary, arranged adjustable.

Claims: 1. Device in a cantilevered frame part of a press section and/or wire section of a paper machine located in a machine hall, in which a cantilevered beam (10) extends between side frames (11, 12), said cantilevered beam (10) including a projecting part (10a), characterised by a loading lever (27) pivotally connected to the projecting part (10a) of the cantilevred beam (10); power means (23) mounted on the projecting part (10a) of the cantilevered beam (10) for applying a force to the loading lever (27); and a pull/draw bar (30) including one end pivotally connected to the loading lever (27) and another end coupled to a stationary counter-member. 2. Device as claimed in claim 1, further including adjustable limiter means (34) provided on the loading lever (27) for limiting the magnitude of downward deflection on the projecting part (10a) of the cantilevered beam (10). 3. Device as claimed in claim 1 or 2, wherein said another end of the pull/draw bar (30) is coupled to a stationary counter-member by coupling means including a bolster (31) mounted in the machine hall in the machine direction having one end bearing against the stationary counter-member, said pull/draw bar (30) passing through the bolster (31), and means connecting said another end of the pull/draw bar (30) to another end of the bolster. 4. Device as claimed in claim 3, wherein the connecting means include threaded nut means (32) fastened to said another end of said pull/draw bar (30). 5. Device as claimed in any of claims 1-4, wherein the stationary counter-member comprises a projecting part (17) of a wall (16) of the machine hall. 6. Device as claimed in any of claims 1-5, wherein the power means is a hydaulic power unit, preferably a hydraulic cylinder (23), for producing a downwardly directed pre-tensioning force (F) on the projecting part (10a) of the cantilevered beam (10).

Inventors: TOERMAENEN, AIMO, Törmänen, Aimo
Applicants: VALMET PAPER MACHINERY INC.
Application year: 1988
Main classification: D21F3
IPC codes: D21F7