Fabric draw-off arrangement in flat knitting machines

A fabric draw-off arrangement for flat knitting machines has a driven fabric draw-off member consisting of a plurality of roller elements and pressure rollers of a fabric pressure member associated with the roller elements which are mounted on a common rocker shaft and are adjustably and resiliently pressable against the respective roller element. In order during knitting to achieve automatically adjustable reproducibly uniform knitting draw-off, the pressure rollers are together pivotable by motor means into variable end positions and are pivotable from these positions and the pressure force of each pressure roller is individually adjustable by motor means.

The invention relates to a fabric draw-off arrangement in flat knitting 
machines of the type comprising: a driven fabric draw-off roller 
consisting of a plurality of roller elements; and pressure rollers of a 
fabric pressure member associated with the roller elements, mounted on a 
common rocker shaft and pressable in an adjustable resilient manner 
against the respective roller element. 
A similar fabric draw-off arrangement, in which however the fabric draw-off 
roller is formed in one piece, is known from DE-C-651296. No drive of the 
one piece fabric draw-off roller is disclosed. 
Furthermore, there is known from FR-A-972602 it is known to provide an 
electromagnet controlled intermittently by a Jacquard device which magnet 
in the respective energised condition raises a plurality of pressure 
rollers together from a one piece fabric draw-off roller via a lever 
linkage. 
The most commonly used fabric draw-off arrangements in flat knitting 
machines generally have a fabric draw-off roller and a fabric pressure 
roller. The knitting, coming from the needles, passes between the two 
rollers and is drawn by a driven fabric draw-off roller. The fabric 
pressure roller has the purpose of pressing the knitting onto the fabric 
draw-off roller and determining the wrapping angle through which the 
knitting passes round the fabric draw-off roller. 
In order to optimise the fabric draw-off, the fabric draw-off roller, as 
known for example from DE-PS No. 3331052, consists of a number of short 
roller elements corresponding to the needle space width, which elements 
differentially and mutually independently adjust the knitting draw-off 
force by spring loading through a predetermined rotational angle. The 
fabric pressure roller in turn has pressure roll elements which may be 
resiliently pressed against the respective roller elements. 
In order to maintain uniform knitting draw-off during knitting, the 
pressure rollers must be adjusted more or less independently in respect of 
their pressure force. 
The adjustment depends upon the yarn to be processed and the texture of the 
knitting which is to be drawn off. When the pressure rollers are set in 
such manner that the knitting is drawn off uniformly, the mesh rows 
leaving the fabric draw-off arrangement horizontally or arcuately, and 
thereafter the entire pressure force must be changed uniformly, all 
pressure rollers must be moved in parallel and newly adjusted. 
The invention is based on the object of providing a fabric draw-off 
arrangement of the type described with which automatically adjustable 
reproducibly uniform knitting draw-off is achieved. 
This problem is solved according to the invention in that by electro-motor 
means the pressure rollers are together pivotable into and out of variable 
end positions, and in that the pressure force of each pressure roller is 
individually settable by electro-motor means. 
Further developments of the invention consist in that the rotation axis of 
the pivot roller is horizontally and vertically settable by electro-motor 
means relative to the central axis of the fabric draw-off roller parallel 
to two coordinate axes or is pivotable in a circular arc about the central 
axis of the fabric draw-off roller. In this way, the wrap-around angle 
alpha, through which the knitting passes around the fabric draw-off 
roller, can be automatically adjusted to the draw-off conditions. 
Advantageously, furthermore the pressure rollers are each individually 
drivable by electro-motor means. 
For pivoting of the pressure rollers in and out, expediently an 
electro-motor is provided which is arranged axially on the pivot shaft. 
Furthermore, advantageously for setting the pressure force of the pressure 
rollers a respective stepping motor is provided to act on a respective 
pressure spring. 
For parallel setting or pivoting of the pivot shaft relative to the fabric 
draw-off roller, expediently an electro-motor is provided which is 
connected to the pivot shaft. 
Furthermore, for driving the pressure rollers, advantageously individual 
stepping motors are provided. 
The electro-motor for pivoting in and out, the stepping motor for setting 
the pressure force, the electro-motor for parallel adjustment or pivoting 
and/or the stepping motors for driving the pressure rollers are 
advantageously controllable via a machine control device of the flat 
knitting machine.

The fabric draw-off arrangement illustrated in FIGS. 1 and 2 has a fabric 
draw-off roller 2 consisting of a plurality of roller elements and a 
fabric pressure member consisting of a plurality of pressure rollers 3. 
Knitting 1, coming from non-illustrated needles and passing between the 
two rollers, is drawn off by the driven fabric draw-off roller 2. The 
pressure rollers 3 of the fabric pressure member have the purpose of 
pressing the knitting 1 onto the fabric draw-off roller 2 and establishing 
the wrap-around angle alpha through which the knitting 1 passes around the 
fabric draw-off roller 2. In order that the fabric draw-off can be 
optimised, the fabric draw-off roller 2 consists of a number of shorter 
roller elements corresponding to the kneedle space width, which elements 
adjust the knitting draw-off force differentially and independently of one 
another by spring loading through a predetermined rotational angle. Each 
roller element has a respective pressure roller 3 of the fabric pressure 
member. The pressure rollers 3 are mounted on a rotatable and lockable 
rocker shaft 5 provided with a locking lever or hand grip 4 in such manner 
that they are exactly opposite the roller elements of the fabric draw-off 
roller 2. Bearings 6 of the pressure rollers 3 are rigidly connected to 
the rocker shaft 5. Each pressure roller 3 is spring loaded with the aid 
of a pressure spring 7 and a clamping screw 8. 
The rocker shaft 5, which is rotatably mounted, assumes two positions. The 
first position is the outwardly pivoted position illustrated in FIG. 2 in 
which the pressure rollers 3 are not in contacted with the fabric draw-off 
roller 2. The other position is that illustrated in FIG. 1 in which the 
pressure rollers 3 are in contact with the fabric draw-off roller 2 and 
are held locked in this position. 
In order during knitting to achieve uniform knitting draw-off, the pressure 
rollers 3 must be more or less individually adjusted in respect of their 
pressure force. The adjustment depends on the yarn to be processed and the 
texture of the knitting which is to be drawn off. The pressure rollers 3 
are adjusted in such manner that the knitting 1 is uniformly withdrawn. 
This is best seen during colour cycling, when the mesh rows must leave the 
fabric draw-off arrangement horizontally or arcuately. If subsequently the 
entire pressure force is uniformly changed, all pressure rollers 3 must be 
moved in parallel and newly adjusted. 
The pivoting in and out of the pressure rollers 3 is achieved with the aid 
of the hand grip 4 which is pinned on the rocker shaft 5 and is operated 
by hand. 
FIG. 3 shows a fabric draw-off arrangement, which, for achieving 
automatically settable reproducibly uniform knitting draw-off is 
constructed in such manner that the pressure rollers are pivotable 
together into variable end positions and are pivotable out of these 
positions and the pressure force of each pressure roller is settable 
individually by electro-motor means. 
By means of an electro-motor 9 arranged axially on the rocker shaft 5, the 
pressure rollers 3 can be pivoted by means of an electro-motor into 
variably pivoted end positions as illustrated in FIG. 3, so that the base 
position of the various adjusted pressure rollers 3 can be adjusted 
accordingly on the knitting 1. The outward pivoting of the pressure 
rollers 3 is likewise achieved together via the electro-motor 9. 
Furthermore, in each case a stepping motor 11 is provided operating on each 
pressure spring 7 of each individual pressure roller 3, by the effect of 
which stepping motor the pressure force of the pressure rollers 3 can be 
individually adjusted. 
An electro-motor 13 connected to the rocker shaft 5 enables the rotation 
axis 10 of the rocker shaft 5 to be adjusted relative to the central axis 
14 of the fabric draw-off roller 2 either by means of a motor in two 
coordinate axes horizontally and vertically (double arrows A) or to pivot 
the rocker shaft 5 by means of a motor through a circular arc about the 
central axis 14 of the fabric draw-off roller 2 (double arrows B). Thus, 
the wrap-around angle alpha can be automatically adapted and adjusted by 
motor means to the draw-off conditions. 
In order to adapt the draw-off forces even further to the draw-off 
conditions, which each of the pressure rollers 3 an individual stepping 
motor 12 can be provided for driving the pressure rollers 3. 
The electro-motor 9, the stepping motor 11, the electro-motor 13 and/or the 
stepping motor 12 are advantageously controllable via a non illustrated 
machine control device of the flat knitting machine.