Roller arrangement for dewatering fabrics

There is disclosed a dewatering roller assembly for Foulard fabrics or the like characterized in that the two rollers through which the fabric strip is passed are caused to bend or deform about mutually corresponding bending lines so that a uniform gap or a predictably variable gap between the rollers is achieved.

This invention relates to roller arrangements for dewatering Foulard and 
like fabrics and comprising a fixedly-mounted roller and a roller which is 
mounted so as to be variable in position for varying the gap between the 
two rollers. 
For dewatering Foulard and like fabrics, in accordance with conventional 
practice, the fabric is moved through the nip between a pair of rollers 
pressed towards one another. It has, however, become apparent that rollers 
which are pressed onto one another with a fabric strip therebetween tend 
to bend or deflect in an uncontrolled manner, so that controlled 
dewatering of the fabric cannot be achieved. 
The problem of the uncontrolled dewatering of such rollers is quite 
generally known in the art. Attempts have been made to obviate this 
bending or deflection, or to control it, as exemplified by German 
Offenlegungsschrift No. 2,222,256 and German Auslegeschrift No. 27,25,573. 
However, these proposals are bound up with undesirably large structural 
expenditure. 
The problem underlying the invention is to provide a roller arrangement for 
fabric dewatering procedures, with which, despite bending or deflection of 
the individual rollers, controlled dewatering of Foulard and like fabrics 
can be achieved. 
Pursuant hereto, the present invention provides a roller arrangement for 
dewatering Foulard or like fabrics and comprising a fixedly-mounted roller 
and a roller which is mounted so as to be variable in position for varying 
the gap between the two rollers, characterized in that the moveable roller 
is mounted with its axle ends each carried by a first arm of a respective 
two-armed lever having a fixed or fixable pivot or fulcrum and in that the 
rigidly-mounted roller has its axle ends projecting beyond respective 
mountings, and in that respective force-actuated expansion mechanisms are 
arranged between each said projecting axle end and the second arm of the 
corresponding two-armed lever. In accordance with a preferred embodiment 
each said force-actuated expansion mechanism is supported so as to be 
axially variable in position at least at the respective projecting axle 
end. Thus, in the arrangement of the invention, no attempt is made to 
prevent roller bending or deflection. On the contrary, the elastic 
behaviour of the rollers is utilized to induce bending of both rollers in 
a desired manner, whereby a roller gap of controlled size is achieved over 
the entire width of the rollers. 
In accordance with a development of the invention it is proposed that the 
power-operated expansion mechanism should be in the form of a flow medium 
cylinder, i.e. a a hydraulic or air piston and cylinder arrangement. This 
provides a particularly simple means for loading the second arms of the 
two-armed levers and of the corresponding axle ends of the fixedly 
arranged roller and of thereby ensuring the desired loading of the rollers 
towards one another.

The illustrated embodiment of the roller arrangement of the invention 
comprises a roller 10 mounted fixedly but rotatably by its axle ends 13 
and 14 in mountings or bearings 11 and 12 in a roll stand which is not 
shown in detail. Arranged in the said roller stand are, furthermore, 
bearing blocks 25 and 26 in which two-armed levers 6 and 7 are mounted so 
as to be swingable about respective pivot points 8 and 9. The first or 
inner arms 4 and 5 respectively of these two-armed levers 6 and 7 each 
have a respective Cardan or universal joint mounting (not shown in detail) 
in which roller axle ends 2 and 3 respectively of moveable roller 1, are 
mounted. 
The fixedly-mounted roller 10 has axle ends 13 and 14 projecting beyond the 
respective mountings 11 and 12. Arranged between these projecting axle 
ends 13 and 14 and the corresponding second or outer arms 15,16 of the 
two-armed levers 6,7 are respective expansion mechanisms 17 and 18. Each 
such expansion mechanism 17, 18 which preferably comprise a piston and 
cylinder arrangement, upon appropriate actuation forces apart the outer 
arms 15 or 16 of the two-armed levers 6,7 and the corresponding projecting 
axle ends 13 or 14 of the fixedly-mounted roller 10 in the directions 
indicated by the arrows 21 and 22. In the exemplified embodiment, each 
expansion mechanism 17, 18 is in the form of a flow medium cylinder or 
hydraulic ram. 
When the expansion mechanisms 17 and 18 are actuated in the described 
manner, the roller 1, which is variable in position, is moved toward the 
fixedly mounted roller 10 and is finally pressed against the Foulard or 
like fabric 19 which is present between the two rollers 1 and 10, and thus 
against the fixedly-mounted roller 10. At the same time, because of the 
resulting reaction force occurring at the expansion mechanisms 17 and 18 
by way of the projecting axle ends 13 and 14, a bending moment is 
introduced into the fixedly-mounted roller 10. This bending moment causes 
deformation or curving of the roller 10. Since the rollers 1 and 10 are 
coupled together forcewise, a corresponding deformation also occurs in the 
moveable roller 1. The introduced bending moments and the magnitude of the 
deformation of the rollers 1 and 10 can be calculated in accordance with 
customary and well established rules of statics, and by varying the ratio 
of the lever arms different effects can be attained. Both of the rollers 1 
and 10 deform as a result of the force, introduced by way of the expansion 
mechanism 17 and 18, in the same magnitude and direction, so that they 
have mutually-corresponding bending lines 23 or 24 respectively. In this 
way the result is achieved that a uniform roller gap 20 occurs over the 
entire effective roller length, so that uniform dewatering of the Foulard 
fabric is achieved. 
The expansion mechanisms 17 and 18 are, preferably supported so as to be 
axially variable in position with their cylinder fastening lugs or eyes 27 
and 28 respectively on the projecting axle ends and can therefore be 
shifted in the direction of the arrow 29,30 respectively. In this way the 
bending behaviour of the rollers 1 and 10 can be influenced in a desired 
manner. For example, a variable roller gap having a desired rate of 
variation can be produced, whereby it is possible to keep the degrees of 
dewatering of the Foulard or like fabric different over its width in a 
desired manner. 
Of course, the described change in position of the power-operated expansion 
mechanisms 17,18 along the axle ends can also be performed by motor (or in 
motorized manner) and during the squeezing and in accordance with a 
predetermined program. In this way it becomes possible to determine and 
also to pre-program the degree of dewatering arbitrarily in the transverse 
direction and in the longitudinal direction of the web.