Apparatus in a cantilevered frame part of a paper machine

Method and apparatus in a cantilevered frame part of a press section and/or wire section of a paper machine in which a cantilevered beam extending between the side frames of the machine is pre-tensioned by applying a force on the cantilevered or projecting part of the beam. The pre-tensioning is produced by a power device, preferably a hydraulic power unit, which produces a downwardly directed pre-tensioning force on the projecting part of the cantilevered beam. The pre-tensioning is applied prior to the replacement of press fabrics or an equivalent operation, and is released after the fabric replacement has been carried out and the side frame at the service side of the machine has been closed or is closeable.

BACKGROUND OF THE INVENTION 
This relates to methods and apparatus in a cantilevered frame part of a 
press section and/or wire section of a paper machine in which a 
cantilevered beam attached between the side frames of the paper machine is 
pre-tensioned by applying a predetermined force in a downward direction of 
the projecting part of the cantilevered beam. 
It is known in the prior art to provide cantilevered beams as part of the 
paper machine frame. The cantilevered beams extend in the transverse 
direction of the paper machine and are arranged in a manner such that at 
the service side of the paper machine, intermediate pieces situated 
between the beam and the frame are openable by means of power units. When 
opened, the intermediate pieces provide an opening through which closed 
fabric loops of the paper machine can be inserted and positioned around 
the rolls and cross beams in connection with the replacement of the 
fabrics. In a manner known in the prior art, the projecting parts of the 
cantilevered beams which are situated at the other side of the paper 
machine, i.e., the operation side of the paper machine opposite from the 
service side at which the openable intermediate pieces are situated, are 
fixed to the ceiling, wall or floor of the paper machine hall, and most 
commonly are fastened to projecting parts of the wall of the paper machine 
hall by means of massive threaded members. The threaded fastening members 
function to support the cantilevered beam when the intermediate pieces on 
the service side of the machine frame are opened. 
The known manner of fastening the projecting part of the cantilevered beam 
involves certain drawbacks resulting from the fact that the fastening 
members are under tension at all times. For this reason, oscillations or 
vibrations spread from the paper machine frame through the fastening 
members to the wall construction of the paper machine hall which, among 
other things, significantly increases the noise level in the paper machine 
hall. 
Another drawback of conventional tensioning fastening arrangements is that 
the large forces applied by them to the cantilevered beams may cause the 
long frame beams to deform. This can adversely affect, for example, the 
parallel alignment of the axles of the various paper machine rolls. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide new and 
improved methods and apparatus in a cantilevered frame part of a paper 
machine which will avoid the drawbacks discussed above. 
Briefly, in accordance with the present invention, this object, among 
others, is obtained by providing a method wherein the pre-tensioning of a 
cantilevered beam is produced by power means, preferably a hydraulic power 
unit, which applies a downwardly directed pre-tensioning force on the 
projecting part of the cantilevered beam when the service side of the 
paper machine frame is opened, such as for replacement of press fabrics or 
the like, and wherein the pre-tensioning is released after the replacement 
of the press fabrics or the like has been carried out and the service side 
of the paper machine frame has been closed or is closeable. 
According to the invention, the above-stated object, among others, is also 
obtained by providing apparatus which, in accordance with a first 
embodiment, comprises a loading arm connected to the end of the projecting 
part of the cantilevered beam by means of an articulation shaft, a 
hydraulic cylinder or the like having one end arranged to act upon the 
loading arm, and the other end being attached to the upper side of the 
projecting part of the cantilevered beam. The loading arm is attached to 
one end of a pull bar by an articulation shaft or the like while the other 
end of the pull bar is attached to a stationary counter-member and the 
loading arm is linked to the end of the projecting part of the 
cantilevered beam. 
In a second embodiment, apparatus in accordance with the invention 
comprises a draw cylinder having a piston which can be withdrawn into the 
cylinder by adjusting the pressure of a pressure medium to produce 
pre-tensioning of the beam. The draw cylinder is attached at its top side 
to the outer end of the projecting part of the cantilevered beam by 
articulation pins or the like while the bottom side of the draw cylinder 
is attached to a stationary counter-member, preferably a projecting part 
of the wall of the paper machine hall. 
In a third embodiment, apparatus in accordance with the invention comprises 
a hydraulic lifting cylinder fitted on or in connection with the top side 
of the projecting part of the cantilevered beam. The hydraulically 
displaceable lifting part of the hydraulic cylinder rests against a 
stationary counter-member, preferably through the intermediate of a press 
bolster. 
In accordance with the invention, the pre-tensioning of the cantilevered 
beam can be released during normal operation of the paper machine, i.e., 
when the service side of the machine frame is closed. The pre-tensioning 
is applied to the cantilevered beam when the service side of the paper 
machine is opened by removing the intermediate piece or pieces so that any 
deformation or sag of the cantilevered beam under its own weight will not 
become unduly large.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings wherein like reference characters designate 
identical or corresponding parts throughout the several views, and more 
particularly to FIG. A, a conventional paper machine frame comprises a 
transverse cantilevered beam 10 extending between opposed side frames of 
the paper machine, namely, between the service-side side frame 11 and the 
operation-side side frame 12. In a manner known in the prior art, the 
projecting part 10a of the cantilevered beam 10 at the operation side of 
the frame is fixed to a projecting part 17 of a wall 16 of the paper 
machine hall. In particular, the projecting part 10 a of cantilevered beam 
10 is connected to the projecting part 17 of wall 16 by means of a draw 
bar 18 that extends through an opening 20 formed through the end of the 
projecting part 10 a of beam 10. The draw bar 18 passes into a box bolster 
19 that bears against the flat bottom side of the projecting wall part 17 
and is mounted in the paper machine hall in the machine direction. The 
ends of the draw bar 18 are threaded and nuts 21 are threadedly fastened 
on the top end of the draw bar to bear against the top surface of the 
projecting part 10 a of beam 10. Similarly, nuts 22 are threadedly 
fastened on the lower end of the draw bar 18 and bear against the bottom 
surface of the bolster 19. The nuts 21 and 22 are generally permanently 
tightened in the illustrated positions to provide a suitable permanent 
support and pre-tensioning for the beam by virtue of the force F applied 
to the beam by the nuts 21. On the other hand, the projecting part of the 
beam applies an equal and opposite force to the bar 18 so that the draw 
bar 18 is subjected to considerable tensile strain. The bar 18 and nuts 
21, 22 are relatively massive and robust members so that it is not 
practical, and usually not possible, to open the tension fastening 
arrangement such, for example, as during replacement of a press felt. 
Still referring to FIG. A, a press roll 13 of the press section is mounted 
on the side frames 11 and 12 by its bearings and axle journals 13a. The 
levers and cylinders for loading the press roll 13 are schematically 
illustrated at 14. Openable intermediate pieces 15 (one shown) are 
provided as part of the service-side side frame 11. When it is desired to 
replace a closed loop of press fabric, the intermediate pieces 15 are 
opened to provide a free space through which a new closed loop of press 
fabric is inserted and located around the press and guide rolls whereupon 
the intermediate pieces are closed and the side frame 11 locked. The 
tensioning fastening means 17, 18, 19, 21, 22 of the projecting part 10a 
of beam 10 is not opened during the replacement operation. Rather, the 
cantilevered beam 10 ha a certain pre-tension at all times resulting from 
the permanent force F to reduce the sag of the end of the beam 10 which is 
proximate to the service-side side frame 11 and to facilitate opening of 
intermediate pieces 15. 
The principles of operation of a first embodiment of apparatus in 
accordance with the invention will now be described with reference to FIG. 
2. A hydraulic cylinder 23 is attached to the upper side of the projecting 
part 10a of cantilevered beam 10 by a bracket 25. A piston rod 24 of the 
hydraulic cylinder is linked to the end of one arm 27a of a bellcrank 
lever 27 at point C by pin 26. Bellcrank lever 27 is pivotally connected 
to the projecting beam part 10a at point A by pin 29 and bracket 28. The 
lower arm 27b of the bellcrank lever 27 is linked to a draw bar 30 at 
point B by pin 33 and bracket 37. When the point B is held fixed and when 
the draw bar 30 is loaded by a tensile force F, the point A and the entire 
projecting part 10a of cantilevered beam 10 to which point A is fixed, 
attempts to turn downwardly so that the main body of beam 10 supported by 
the side frame 12 attempts to turn upwardly. In this manner, the desired 
pre-tensioning of the beam 10 is produced. The magnitude of the 
pre-tensioning can be adjusted by adjusting the position of a limiting 
screw 34. The required pre-tensioning force F can be set by adjusting the 
ratio of the dimensions S and M of the bellcrank lever 27 while the size 
of the loading cylinder 23 and the loading pressure P from pressure source 
39 can be maintained constant. As an example, the dimension S may be 300 
mm. while the dimension M may be 1000 mm. After the intermediate frame 
pieces 15 have been opened and the felts replaced, the pre-tensioning of 
the beam 10 can be released in accordance with the method of the invention 
by depressurizing the hydraulic cylinder 23 and by pivoting the bellcrank 
lever 27 against the limiting stop 35 at 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. Referring 
to FIG. 1, the lower arm 27b of the bellcrank lever 27 is attached to the 
draw bar 30 by means of an articulated joint 33'. The draw bar 30 passes 
through a box bolster 31 mounted in the paper machine hall in the machine 
direction. The draw bar 30 is fixed by means of nuts 32 threaded over its 
lower end which bear against the lower surface of the box bolster 31. The 
embodiment of FIG. 2 differs from that of FIG. 1 in that the upper end of 
the draw bar 30 in the embodiment of FIG. 2 is connected to a forked 
bracket 37 by means of a nut 36, the bracket 37 being attached to the 
lower arm 27b of the bellcrank lever 27 at point B by means of an 
articulation shaft or pin 33. In other respects, the construction of the 
embodiment illustrated in FIG. 1 is the same as that illustrated in FIG. 
2. 
Another embodiment of the invention is illustrated in FIG. 4. In this 
embodiment, a piston rod 41 of a draw cylinder 40 is connected to the 
outer end of the projecting part 10a of cantilevered beam 10 by means of 
brackets 47 and an articulation pin 42. At its bottom end, the draw 
cylinder 40 is connected to the draw bar 44 by an articulation pin 43. The 
draw bar 44 passes through the box bolster 45 which is mounted in the 
machine hall in the machine direction. The draw bar 44 transfers the 
lifting force to the box bolster 45 by means of nuts 46. The flange 48 at 
the top end of the box bolster 45 bears against the lower flat side of the 
projecting part 17 of wall 16. When a certain pressure P is introduced 
into the draw cylinder 40 from a pressure source 39, the piston rod 41 
retracts into the draw cylinder and tends to pull the projecting beam part 
10a downwardly, whereby at a certain time, appropriate pre-tensioning is 
provided in cantilevered beam 10. 
Referring now to FIG. 5, another embodiment of apparatus in accordance with 
the invention includes a lifting cylinder or jack 50 fixed to the top side 
of the projecting part 10a of cantilevered beam 10 while the lifting part 
51 of the lifting cylinder 50 bears against the lower flange 55 of the box 
bolster 52 mounted on the machine hall in the machine direction. The upper 
flange 53 of box bolster 52 bears against the flat lower side of the 
projecting part 17 of wall 16. Upon pressurizing the lifting cylinder 50 
with a pressure P from the pressure source 39, the lifting part or piston 
51 pushes upwardly against the box bolster whereupon the pre-tension 
required in connection with the replacement of a felt or the like is 
provided in cantilevered beam 10. The pre-tension can also be released in 
a easy manner as will be understood. 
It is a feature of the method of the invention that the power units 23, 40 
and 50 are depressurized so that the cantilevered beam is not 
pre-tensioned during normal operation of the paper machine. When a felt or 
the like is to be replaced and the intermediate pieces 15 of the side 
frame 11 are opened by means of cranes or the like, a pre-tension of an 
appropriate magnitude is maintained in the cantilevered beam 10. The 
magnitude of the pre-tensioning is chosen so that the sag of the end of 
the cantilevered beam 10 situated at the service-side side frame 11 does 
not become unduly large. As a rule, the magnitude of the pressure P 
applied to the power units 23, 40, 50 when pre-tensioning is required does 
not require any regulation. Rather, and the magnitude of the 
pre-tensioning force F and magnitude of the deflection of the projecting 
part 10a of beam 10 in the downward direction are determined by mechanical 
devices. For example, in accordance with the embodiments of FIGS. 1 and 2, 
the limiting screw 34 provided at the end of the lower arm 27b of the 
bellcrank lever 27 can be adjustable to regulate the magnitude of the 
pre-tensioning force and deflection of the projecting beam part. 
Obviously, numerous modifications and variations of the present invention 
are possible in the light of the above teachings. It is therefore to be 
understood that within the scope of the claims appended hereto, the 
invention may be practiced otherwise than as specifically disclosed herein 
.