Technical Field

The pres nt invention relates to a framework for a press in a machine for the manufacture of a fibrous web, said press including a first press member and a counter press member, said press members being elongate and extending parallel to each other across the width of the machine, at least one of said press members being movable in a loading/unloading direction to form a press nip with the other member, at least one endless belt, one of said press members being located within the loop formed by said endless belt, said belt passing through said nip together with the web, said framework including two side frames, one adapted to be located on the drive side of the machine and the other one on the operational side of the machine in a parallel relationship to each other, each of said siat frames having two columns, one located upstream and the other downstream of said press nip, and extend ⁱ ng parallel to each other in a direction other than substantially perpendicular to said loading/- unloading direction, each of the two columns on the operational side of the machine having an interposed removable section for permitting an exchange of said endless belt.

Background Art

A framework of this kind is disclosed in FI-B-65 832. The removable sections are inserted in gaps formed between the ends of adjoining sections of the columns on the operational side of the paper or board machine. Usually, eyeboKs or screws, which are pivotably attached to one of the column sections, bridge the gap in each such column to facilitate quick loosening of the screw joint, removal and insertion of the removable sect.on, and tightening of the joint. Such bolts or screws have to be very robust since they are exposed to high tension when the press is operating at its maximum permissible load. Also, in some cases it can not be avoided that the bolts or screws will be exposed to high bending moments.

Disclosure of Invention

The object of the present invention is to provide a framework, in which the elements of the screw joints are exposed to far lower tensional forces and bending moments and, consequently, can be of considerably smaller dimensions.

According to the present invention, this object is achieved by providing individual means for prestressing each column axially with a comoressive force at least substantially equal to a tensile force induced in the respective column by a maximum permissible press force in said nip.

Preferably, each of the prestressing means for the two columns on the operational side of the machine has an elongate two-part tension element, said two parts being disengagable from each other at a location proximate to said removable column section, and at least one of the two parts being, in an unconnected condition, axially displaceable in relation to the other to form a gap at said location so as to permit removal of the removable section of the column and exchange of said endless belt.

Suitably, the two parts of each two-part tension element are connected to each other by means of a quick connect/disconnect coupling having a socket member and a mating plug member. A quick connect/disconnect coupling reduces the time required for exchange of the endless belt. Then it is preferred that the two coupling members are engagable and disengagable by a rotation of the one through an angle of about 90° relative to the other.

Preferably, each of said columns includes a box beam section, and each of said prestressing means includes an elongate tension element extending axially inside the box beam section. A box beam has an improved stiffness, and the locating of the elongate tension element inside the box beam facilitates the avoidance of bending moments caused by the prestressing and affords some protection of the tension element.

Further, it is preferred that each of said prestressing means includes a hydraulic nut, and each tension element has a fixed end, the hydraulic

nut engaging the other end for tensioning the tension element. The utilization of hydraulic nuts facilitates the prestressing of the columns with uniform compressive forces.

The compressive force suitably exceeds the induced tensile force in each column by a safety margin.

The present invention will below be described more in detail with reference to the appended drawings, which illustrate a preferred embodiment of the invention.

Brief Description of Drawings

Figure 1 is a simplified end view of a press in a paper making machine seen from the operational side of the machine and shows among other things a side frame included in the framework of the press.

Figure 2 is a view primarily in vertical section, but with some components shown in elevation, of the left column and associated prestressing means of the press framework shown in figure 1.

Figure 3 is an enlarged fragmentary sectional view showing in greater detail cooperating socket and plug members of a coupling of the prestressing means shown in figure 2.

Figure 4 is a sectional view similar to figure 3 but taker Λ a right angle thereto.

Figure 5 is a simplified fragmentary side elevational view of that part of the figure 3 column containing a removable column section, and of a jack and an actuator associated therewith.

Figure 6 is a perspective view of the operational side of a papermaking machine press having a framework in accordance with the present invention, components of the press being shown in positions occupied by them during exchange of a felt belt.

Best Mode for Carrying Out the Invention

Figure 1 shows a press in a machine for the manufacture of a paper or board web. The press includes a first press member 1 and a counter press member 2, which are elongate and extend parallel to each other across the width of the machine. At least one of the press members is movable in a loading and unloading direction for forming a press nip with the other member.

In the shown preferred embodiment the counter press member is a controlled deflection roll 2 and the first press member is a press shoe 1 having a concave surface adapted to the surface of counter roll 2 to form an extended nip with counter roll 2. Press shoe 1 is incorporated in a shoe type press roll 3, which has a flexible roll jacket 4 and preferably is of the type disclosed in SE-B-464 922. It is also possible, but less preferred, to substitute a shoe press device having an endless press belt, substantially as disclosed in said FI-B 65 832, for the shoe type press roll 3. In other possible but less preferred embodiments both of the press members may be shoe press devices having a plane surface instead of a convex one or, alternatively, they may both even be conventional press rolls.

The press includes at least one endless belt 5. In the shown embodiment the belt is an endless press felt 5, inside the loop of which the shoe type press roll 3 is located. Together with the paper or board web 6 manufactured in the machine the felt 5 passes through the press nip for absorbing water pressed out from the web 6 in the nip. In the embodiment illustrated in figure 1 the press is single felted, the web 6 being pressed between the felt 5 and counter roll 2, but it is also possible in another embodiment, not shown, to have the press double felted. Then, also counter roll 2 will be located inside the loop of an endless press felt and web 6 will be pressed between the two felts. Of course, it is also possible, if desired, to provide yet another endless belt of water receiving structure, for example, to run through the press nip sandwiched between the press member and its surrounding felt loop for receiving water possibly passing from the web through the felt.

Felt 5 runs guided by a plurality of guide rolls 7 that include a stretch roll 8 and an alignment roll 9. Conventional felt conditioning equipment is also provided but not shown. There are also two guide rolls 10 for the paper or board web 6, one on each side of the press nip.

The framework for the press includes two side frames, one side frame (not shown) being located on the drive side of the machine and the other, designated by reference numeral 11, on the operational side of the machine in a parallel relationship to each other. Each of said side frames has two columns. One column 12 is located upstream and the other 13 downstream of the press nip. Columns 12 and 13 extend parallel to each other in a direction other than substantially perpendicular to said loading and unloading direction of the press. In the shown preferred embodiment they are vertical and extend parallel to said direction. To complete the side frames, columns 12 and 13 are interconnected at their tops by an upper cross piece 14 and at their bottoms by a lower cross piece 15. The two side frames are interconnected by an upper cross beam 16 anchored to a top surface of each upper cross piece 14, and two lower cross beams 16 and 17 anchored to a vertical surface of each of columns 12 and 13, respectively, and near the bottoms thereof. Each side frame is secured to a bottom rail 60 for the paper or board machine, and each bottom rail is secured to the floor 61.

The bottom side of each upper cross piece 14 has a ch< red recess for receiving and positioning a bearing housing 19, in which the shoe type press roll 3 is journalled. To avoid crowding in figure 1 support structures for rolls 7,8,9 and 10 is not shown. The counter roll 2 is journalled in bearing housings 20, of which the one on the operational side of the machine is shown. Each bearing housing 20 is mounted on a substantially horizontal arm of a two-armed lever 21 having the other arm extent ng up the upstream column 12. Lever 21 is pivotable on an axis on a level with the rotational axis of counter roll 2, and an actuator 22 is associated with each lever 21 for raising the counter roll 2 to an operating position and lowering it out of said position. A pivotable support 23 is mounted to be swung into a first position, where it supports the free end of lever 21 when counter roll 2 is in its operating

position, and a second position, where lever 21 and counter roll 2 are free to be lowered.

To permit exchange of endless felt 5 and any possible other endless belt extending through the press nip, each of the two columns 12 and 13 on the operational side of the machine has an interposed removable section 24 and 25, respectively.

In accordance with the present invention individual means are provided

10 for prestressing each one of the four columns 12 and 13 with a compressive force at least substantially equal to a tensile force induced in the respective column by a maximum permissible force in the press nip. The prestressing compressive force preferably exceeds the induced tensile force by a safety margin, which may be on the order of 0.3 MN or 25%, for

__.o example.

Figure 2 illustrates the prestressing means, generally designated by reference numeral 26, for column 13, which is located downstream of the press nip and on the operational side of the machine. As the two

20 prestressing means on the operational side of the machine are identical and also the two associated columns 12 and 13 are identical apart from a minor modification required by the provision of the two-armed lever 21 and its actuator 22, the description below of the preferred design of the prestressing means 26 and that of column 13 applies also to column 12 and - its prestressing means.

The prestressing means 26 has an elongate two-part tension element 27, suitably in the shape of a two-part circular rod. The two parts, designated 28 and 29, are disengagable from each other at a location

30 proximate to the removable section 25 of column 13. After disengagement at least one of the two parts, in figure 2 the lower part 29, is axially displaceable in relation to the other to form a gap at said location so as to permit removal of the removable section 25 of column 13 and exchange of press felt 5 or other endless belt.

35

The two parts 28 and 29 of tension rod 27 may be connected to each other in a plurality of ways obvious to a person skilled in the art. However,

in the illustrated preferred embodiment they are connected to each other by means of a quick connect/disconnect coupling 30 having a socket member 31 and a matching plug member 32, which members, as can be inferred easily from figures 3 and 4, are engagable and disengagable by a rotation ⁼ of the one through an angle of about 90° relative to the other.

Preferably, each of the columns 12 and 13 includes an upper box beam section 33 and a lower forked section 34, where each of the furcations also are box beam sections. The two furcations are located side by side ° in the cross machine direction, so that with respect to the operational side of the machine one furcation is proximate and the other distal. In each side frame (11) the two-armed lever 21 and the pivotable support 23 therefor are doubled, one lever being located in the proximate furcation and the other in the distal furcation of column 12, and one pivotable

-° support being located in the proximate furcation and the other in the distal furcation of column 13, while actuator 23 is located in the space between the furcations of column 12 and common to both of the levers. The two pivotable supports 23 are secured to a common pivot shaft.

0 Also the upper cross piece 14 and the lower cross piece 15 of each side frame 11 preferably are box beam sections, and the upper cross piece 14 is lying on top of the top ends of columns 12 and 13. The two-part tension rod 27 has an upper end located at a level above the upper cross piece 14 and extending vertically downwards through the end of upper 5 cross piece 14 and the upper box beam section 33 and through part of the space formed between the two furcations c ~ the lower forked section 34. The lower end of the two-part tension rod 27 exten, - through a hole provided in a heavy cross plate 35 fixed to the two furcations of the forked column section 34 in a manner permitting the transfer of forces 0 from rod 27, when tensioned, to column 13.

Both ends of each part of the two-part tension rod 27 have an external thread. A bottom nut member 36 having a matching internal thread is mounted on the bottom end of the lower part 29 of tension rod 27 for ⁵ bearing against the bottom surface of cross plate 35, Likewise, plug member 32 and socket member 31 have internal threads and are mounted on the matching threaded top end of lower rod part 29 and bottom end of

upper rod part 28, respectively. Also a tensioning device, preferably a hydraulic nut 37, has a matching internal thread and is mounted on the top end of upper rod part 28. Locking elements such as keys, not shown, are provided for preventing unintentional relative rotation between the threaded elements.

The hydraulic nut 37 is of conventional design and has an inner top member 38, which is provided with the internal thread for engagement by the top of tension rod 27, and an outer bottom member 39. Inner top member 38 has a stepped outer surface and outer bottom member 39 has a matching stepped inner surface, and they define between them an annular pressure chamber 40. A conduit 41 is provided for supplying a pressurized hydraulic medium, such as oil, to pressure chamber 40. Thereby, inner top member 38 is displaced axially upwards from outer bottom member 39, which bears against a top surface of cross piece 14, and tension rod 27 becomes tensioned. Simultaneously, an annular gap is formed between the top end of outer bottom member 39 and a flange portion on the inner top member 38. After insertion of a two-part distance ring 42 of suitable axial thickness into the gap, the pressure in the pressure chamber can be relieved. The distance ring 42 will keep tension rod 27 under the desired tension.

Alternatively, distance ring 42 may be dispensed with if said flange portion is in the shape of a nut, which when tension rod 27 is being tensioned by hydraulic nut 37 can be screwed down on the body of inner top member 38 to bear against the top surface of outer bottom member 39.

As shown most clearly in figures 3 and 4, plug member 32 of quick connect/disconnect coupling 30 basically has a frustoconical top portion 43 and a cylindrical bottom portion 44, from which portions two identical and diametrically located sections are cut away to provide two vertical parallel sides 45 of the plug member 32. Socket member 31 has a recess with a matching frustoconical top portion 46 and a cylindrical bottom portion 47 and, in addition, an entrance slot 48 adapted to permit the passage of plug member 32 when the parallel sides 45 of the plug member are parallel to the longitudinal direction of the entrance slot 48, but to prevent the passage of the plug member 32 after a rotation thereof

through an angle of about 90° in relation to the slot 48. After said rotation, the two outermost portions of the bottom surface of plug member 32 bear against two shoulders defined between the inner end of the entrance slot and the cylindrical interior wall radially outside thereof. It is preferred, but not shown, that a plurality of stops are provided on the interior walls of the socket member 31 for preventing the socket member from being rotated past its desired end positions, one where the extension of the entrance slot 48 coincides with that of the plug member 32, and the other where they form an angle of 90° with each other. Such stops may be screws, for example, extending radially through the wall of the socket member 31 and into the recess of the socket member.

With reference to figure 2 again, means are provided for rotating the upper rod part 28 of the two-part tension rod 27 and, thus, also the socket member 31 between its end positions after removal of distance ring 42 and release of any pressure in the pressure chamber 40. In the shown preferred embodiment these means include an arm 49 fixed to the top end of upper rod part 28 and extending radially therefrom. To facilitate the rotation of upper rod part 27 and socket member 31, it is suitable that the release of the pressure in pressure chamber 40 makes socket member 31 sink one or a few millimetres, so that the outermost portions of the bottom surface of plug member 32 do not engage the two shoulders inside socket member 31.

As shown in figure 2, an actuator 50 is mounted vertically in the space between the two furcations of column 13 for lowering and raising the lower rod part 29 with plug member 32 and bottom nut member 36. Actuator 50 has one end connected to column 13 and the other to bottom nut member 36. To guide the downward and upward movement the bottom nut member 36 has a guide follower 51 engaging a guide rod 52 vertically mounted in column 13 in the space between the two furcations. The bottom positions of the movable members are shown in dashed and dotted lines, and the bottom position of plug member 32 is located below removable column section 25, so that removal and insertion of said section will not be obstructed.

To ensure a correct position of tension rod 27 inside column 13, a plurality of collar bearings 53 are provided. One is shown mounted at the top of column 13, another immediately below the bottom position of plug member 32 and a third at some distance above cross plate 35. The third collar bearing 53 is supported by a bracket, not shown, mounted on supporting structure, not shown, for cross plate 35.

For facilitating removal and insertion of removable column section 25 after the lowering of lower rod part 29 with plug member 32 and bottom nut member 36 to its bottom position, two brackets 54 and 55 may be mounted on column 13, one (54) below and the other (55) above section 25 as shown at the right-hand side of figure 5. After the positioning of a jack 56 between the brackets, the column section 33 located on top of removable section 25 can be lifted a few millimetres to permit easy removal of section 25. As shown at the left-hand side of figure 5 a pivot joint 57, to which the movable member of an actuator 58 is connected, may be substituted for upper bracket 55 and jack 56 or used in addition thereto. When not in use, the actuator 58 may be rotated through an angle of 180° with reference to pivot joint 57 so as to be located in a vertical inactive position above pivot joint 57. Upon inactivation of jack 56 and/or actuator 58 the upper section 33 of column 13 sinks down somewhat but leaves a gap to the lower section 34 of the column, and after removal of jack 56 and/or actuator 58 the gap is free from obstructions so that an exchange of felt 5 can be carried out.

The two columns in the side frame on the drive side of the machine do not have any removable section similar to section 25, and the tension rods used for prestressing these columns are one-part rods extending from the hydraulic nut to the bottom nut member. Consequently, no quick couplings are used in these two columns, nor any actuators, guide followers or guide rods similar to actuator 50, guide follower 51 and guide rod 52, respectively.

Figure 6 illustrates the installation of a new felt belt 5 in a press of a papermaking or boardmaking machine. The counter roll 2 carried by the double two-armed levers is lowered. The tension applied by the two hydraulic nuts 37 to the two two-part tension rods on the operational

side of the machine is reduced to zero, the upper rod parts carrying the socket members of the quick connect/disconnect couplings are disengaged from the lower ones carrying the plug members, and the lower rod parts are moved downwardly by means of the vertical actuators inside columns 12 and 13 to permit removal of the removable column sections 24 and 25. A bracket 62 is temporarily mounted on the bearing housing 19 for the shoe type press roll 3, a temporary support column 63 is placed under the bracket 62, and at the top of the column 63 there is a jack 64 engaging the bottom side of the bracket. After loosening some eyebolts (not shown) located at the removable column sections 24 and 25, these removable sections can be pulled out of columns 12 and 13, respectively, and let down so that they will hang vertically adjacent the now empty spaces they are normally occupying. Further, to facilitate the change of the felt 5 the stretch roll 8 is temporarily removed by a traveling overhead crane (not shown) to a position beside the small diameter guide roll 7 straight above the upper cross beam 16. The worn felt can now be pulled out of the press sideways to a position between the side frame 11 on the operational side of the machine and the temporary support column 63. If desired, the jack and/or the actuator shown in figure 5 may now be used for supporting the upper portion of the press so as to permit removal of the jack 64 placed between the bracket 62 and the temporary support column 63 and substitution of a new felt 5 for the worn one through the gap formed by the removal of jack 64. For completing the installation of the new felt, the above steps are carried out in reverse order.

Terms, such as "columns", "upper", "lower", "vertical", "horizontal" et cetera, used in the above description and in the appended claims are intended to be interpreted as describing relative positions. In an embodiment where the loading and unloading direction of the press is horizontal, for example, instead of vertical as illustrated in the drawings, "columns" 12 and 13 would be horizontal instead of vertical.