Method and circular knitting machine for producing knit goods with combed-in fibers

The invention concerns a process and a circular knitting machine for the production of knit goods with combed-in fibers, in which an amount of fibers synchronous with the needle cylinder rotatory speed is fed to a teasing cylinder rotating at high speed, transferred by the latter to the comb-in zone, and taken from the needles in the comb-in zone without contacting the teasing cylinder. To prevent the development of areas overfilled with fibers or short of fibers in the finished knit goods on account of the contact-less fiber feed, during or before abrupt reductions or increases in the rotatory speed of the needle cylinder, at least temporarily smaller or larger amounts of fibers are fed to the comb-in zone than corresponds to the synchronous amount of fibers.

BACKGROUND OF THE INVENTION 
The invention relates to a method of producing, on a circular knitting 
machine having a rotatable needle cylinder, knit fabrics having combed-in 
fibers and a preselected fiber density, the method comprising the steps of 
delivering an amount of fibers synchronous with the needle cylinder rotary 
speed to a teasing cylinder rotating at high speed, yielding fibers from 
said teasing cylinder to a comb-in zone and transfering fibers in the 
comb-in zone to the needles without the needles contacting the teasing 
cylinder. The invention further relates to a knitting machine on which 
this method can be carried out. 
In methods and circular knitting machines of this kind (U.S. Pat. Nos. 
4,458,506 and 4,546,622 the fibers, in contrast to conventional methods 
and circular knitting machines U.S. Pat. No. 3,709,002 are combed 
contactlessly into the needle hooks, the term "contactlessly" meaning that 
the needle hooks do not pass through teasing hooks. The transfer of the 
fibers to the comb-in zone is performed as in circular knitting machines 
with conventional combs under conditions synchronous with the rotation of 
the needle cylinder. The term, "synchronous conditions", is to be 
understood to mean that, at any constant rotatory speed of the needle 
cylinder, the fibers are always delivered to the comb-in zone at a 
preselected, constant amount of fibers per unit time, so as to produce 
goods having a preselected, constant fiber density. On the other hand, the 
amount of fiber fed to the comb-in zone changes synchronously in the case 
of changes in the needle cylinder rotatory speed, in order that, in the 
event of reductions or increases in the needle cylinder rotatory speed, 
correspondingly less or more fibers will be delivered to the comb-in zone, 
thereby assuring that the preselected fiber density will be achieved at 
any rotatory speed of the needle cylinder, i.e., especially during the 
execution of start and stop cycles. If the feed of fiber to the teasing 
cylinder by means of feed rolls, for example, "synchronous conditions" 
means that the feed rolls and the needle cylinder are driven from a 
single, main drive through gears, belts, rollers or the like, so that the 
ratio of their rotatory speeds is the same at all rotatory speeds of the 
needle cylinder, and that, independently thereof, the teasing cylinder is 
driven always at the same high rotatory speed at all needle cylinder 
speeds. 
Experiments on such circular knitting machines with contactless fiber feed 
have surprisingly shown that, during those phases in which the needle 
cylinder is subjected to abrupt changes of rotatory speed, such as is the 
case especially during the start and stop cycles and during "tip" 
operation, undesirable deviations from the preselected fiber density can 
result, which lead to thick and thin areas in the finished knit goods. 
"Thick and thin areas" in this connection refers to those points in the 
finished goods at which the fiber density is lower or higher than the 
preselected fiber density. The length of the thick and thin areas appears 
to be dependent upon a number of factors, such as the length of time for 
which the needle cylinder is stopped, the duration of the braking or 
accelerating cycles of the needle cylinder until it reaches a full stop or 
the production speed, the fiber length, or the titer of the fibers. 
The invention is addressed to the problem of improving the method and the 
circular knitting machine of the kind defined such that thick and thin 
areas will be largely avoided. In particular, those thick and thin areas 
are to be avoided such as can develop upon the abrupt braking of the 
needle cylinder to a stop, e.g., due to thread breakage or the like, or 
upon the acceleration of the needle cylinder from a full stop until it 
reaches the production speed. 
The method of this invention is characterized by substantially maintaining 
constant the preselected fiber density also when abrupt changes of the 
rotary speed of the needle cylinder occur by at least momentarily feeding 
amounts of fibers which differ from the synchronous amount of fibers to 
the comb-in zone. A circular knitting machine for the production of knit 
goods with combed-in fibers comprises according to this invention a 
rotatable needle bearing needle cylinder, a card which has a means for 
feeding the fibers, a comb-in zone through which the needles pass for the 
purpose of contactless fiber pickup, and a teasing cylinder rotating at 
high speed which takes the fibers from the feed means and gives them to 
the comb-in zone, and a drive means for the synchronous driving of the 
needle cylinder and feed means. The card has a controller which becomes 
active upon abrupt changes in the rotary speed of the needle cylinder for 
the synchronous changing of the amount of fibers yielded to the comb-in 
zone. 
The invention brings with it the surprising advantage that a great number 
of thick and thin areas can be prevented by the simple measure of feeding 
fewer fibers upon the abrupt braking of the needle cylinder, but more 
fibers upon the acceleration of the needle cylinder from a full stop, than 
would correspond to the synchronous amounts of fibers. 
Additional advantageous features of the invention will be found in the 
subordinate claims. 
The invention will now be further explained in conjunction with the 
appended drawing of a preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In FIG. 1, and in U.S. Pat. Nos. 4,458,506 and 4,546,622, a circular 
knitting machine for the production of high-pile knit goods 1 contains a 
rotatable needle cylinder 2 in which vertically displaceable knitting 
needles 3 with hooks 4 are mounted, which are moved up and down in the 
area of at least one knitting system by means of stationary cam parts 5a 
and 5b, for the purpose of producing a base knit fabric from the yarns 
that are not shown. The fibers are loosened up and combed into the knit 
fabric by means of at least one comb or carding unit 6, which consists, 
for example, of a feed system consisting, for example, of two feed 
cylinders 7a and 7b for feeding a condensed sliver or fiber band 8, a 
teasing or separating cylinder 10 intended to break up the fiber band 8 
into individual fibers 9, and a comb-in zone 11 through which the knitting 
needles 3 and their hooks 4 pass in order to pick up the fibers 9. 
The teasing cylinder 10, which can rotate in the direction of an arrow P, 
is covered on its circumference with a clothing 13 bearing outwardly 
projecting hooks 14. The teasing cylinder 10 is driven at a substantially 
greater circumferential speed than the feed cylinders 7, and therefore 
pulls the fiber band 8 apart in single fibers 9. 
To prevent the fibers picked up by the teasing hooks 14 from being flung 
back out of the hooks, despite the great effective centrifugal forces 
acting on them due to the high speed of the loosening cylinder 10, the 
comb 6 has a shroud 15, which is preferably a part of a fully enclosed 
casing 20 surrounding the teasing cylinder 10 and the comb-in zone 11, and 
is situated opposite the outer circumference of the teasing cylinder 10, 
and contains an entry 16 for the fiber band 8 fed by the feed cylinders 7 
and an exit opening 17 through which the fibers 9 can be fed into the 
comb-in zone 11. The shroud 15 then defines the outside of a teasing and 
accelerating section 18 beginning directly at the entry opening 16 and 
indicated by an arrow, within which the shroud 15 is at a small, but 
otherwise constant distance of, for example, less than one millimeter, 
from the tops of the teasing hooks 14 of the teasing cylinder 10, so that 
the fibers cannot come off the teasing hooks 14. The teasing and 
accelerating section 18 is then followed, in the direction of rotation of 
the teasing cylinder, by a teasing or detachment section or zone 19 
indicated by an arrow, which ends at the exit opening 17 and is at a 
distance from the tips of the teasing hooks 14 which gradually increases 
in the direction of rotation to a value of, for example, several 
millimeters. Therefore, the fibers 9 can be loosened in this section 19 by 
the centrifugal force, entrained tangentially in the air stream produced 
by rotation of the teasing cylinder, and combed into the knitting needles 
lifted by the cam parts 5 in the comb-in zone, without coming in contact 
with the teasing hooks 14. 
With the teasing cylinder 10 there is associated a drive independent of the 
conventional needle cylinder drive, in the form of a motor 33 which drives 
the teasing cylinder 10 at a speed that is constant at all knitting 
machine speeds, or can be adapted to a certain extent to the momentary 
knitting machine speeds and/or the properties of the fibers involved. The 
motor 33 can be a reversible-pole motor having at least two rotatory 
speeds. 
In known circular knitting machines of this kind (U.S. Pat. Nos. 4,458,506 
and 4,546,622), the feed cylinders 7 are driven synchronously with the 
needle cylinder rotatory speed. According to the invention, however, a 
drive 34 is provided--a motor for example--which is connected on the one 
hand by a gear 35 to the crown gear of the needle cylinder 2, and on the 
other hand by additional gears 36, a shaft 37 and a belt drive 38 to one 
input of a differential gearing 39. Another input of this differential 
gearing 39 is connected by another belt drive 40 to the output shaft of a 
servo motor 41. On the output shaft of the differential gearing 39 there 
is fastened a belt pulley 42 which is connected by a belt 43 to another 
belt pulley 44 on whose shaft there is fastened a worm 45. This worm is 
engaged in the usual manner with a worm gear which is mounted on one of 
the shafts of the feed cylinder 7 and serves to drive the latter. On the 
basis of the drive just described, it is possible to drive the feed 
cylinders 7 either synchronously with the needle cylinder if the 
servomotor 41 is stopped, or, if motor 34 is stopped, synchronously with 
the rotatory speed of the servomotor 41, or, if both motors 34 and 41 are 
running, the feed cylinders can be driven at a resultant speed. If the 
servo motor 41 is a reversible motor, the feed cylinders can be driven 
either at a greater or at a lower rotatory speed than the momentary 
rotatory speed that can be produced through the gears 35, 36 and 38 and is 
synchronous with the needle cylinder speed, since the differential gearing 
will add or subtract the two input speeds depending on the direction of 
rotation of the servo motor 41. The differential gearing thus constitutes 
a means for the interruption and restoration of synchronism between the 
feed means and the needle cylinder. 
According to FIGS. 2 and 3, the casing 20 has in the area adjacent the 
needle backs a fixed fiber guiding plate 47 whose end at the comb-in zone 
11 is of streamlined shape. The fiber guiding plate 47 is disposed such 
that, in back of the needles 3, and between it and an imaginary 
cylindrical surface 47 in which the tips of the teasing hooks 14 move, a 
wedge-shaped gap 49 is formed (U.S. Pat. No. 4,546,002). Furthermore, in 
back of the fiber guiding plate 47, in the direction of rotation of the 
teasing cylinder 10, there is provided an ejection flap 50 which is 
articulated on a pivot pin 51 on the fiber guiding plate 47 and is 
preferably a part of the latter. The other end of the ejection flap 50 
adjoins, along a sloping junction, a fixed casing part 52, the components 
47, 50 and 52 extending preferably at least over the width of the teasing 
cylinder. The ejection flap 50 has a lug 53 which is joined to an actuator 
55 which consists, for example, of a solenoid coil with a plunger 54 which 
can be extended and retracted and is linked to the lug 53. This actuator 
55 is disposed laterally beside the teasing cylinder 10 and is pivoted on 
a pivot pin 56 on a stationary machine part. In the disengaged position, 
e.g., when the plunger 54 is retracted, the fiber guiding plate 47 and the 
closed ejection flap 50 form a substantially continuous fiber guiding 
surface (FIG. 2) which prevents fibers from being thrown off the teasing 
hooks 14 and produces a combing out and orientation of the fiber tufts 
which have already been laid into the needles but are still in the comb-in 
zone 11. If, however, the plunger 54 is pushed out of the solenoid 55 by 
means of an electrical signal, the rear end of the ejection flap 50 is 
rocked in the manner shown in FIG. 3 radially away from the teasing 
cylinder 10 to the working position. This results in the formation of an 
ejection opening 58 virtually tangential to the circumference of the 
teasing cylinder 10, and any fibers that are still on the teasing hooks 14 
are released by the centrifugal forces and then are, for example, 
aspirated by a central aspirating system. 
Preferably ahead of the needles 3, in the direction of rotation of the 
teasing cylinder 10, there is disposed in accordance with the invention a 
blocking means 60 for blocking the needle hooks 4 that are in the comb-in 
zone 11. This blocking means 60 serves to block off the open needle hooks 
4 if necessary, so that they will not pick up any more fibers. In 
accordance with FIGS. 1 to 3, the blocking means 60 is a thin, e.g., 0.15 
mm thick, plate extending preferably at least over the width of the 
teasing cylinder 10 and guided displaceably in a slotted guide 61 which is 
provided in a wall portion 62 (FIGS. 2 to 4) surrounding the teasing 
cylinder. The slotted guide 61 runs from one exit end 63 of the wall 
portion 62 situated ahead of the comb-in zone in the teasing cylinder's 
direction of rotation, substantially tangentially to the teasing cylinder 
10, and toward a gap 64, which is defined on the one hand by the upper 
ends of the needle hooks 4 raised to receive fibers, and on the other hand 
by the cylindrical surface 48, and whose width is slightly greater than 
the thickness of the blocking means 60. The end of the blocking means 60 
protruding from the exit end 63 is linked to one end of a rocking arm 65 
which is pivoted in its central portion at 66 and is linked at its other 
end to an actuator 68 which consists, for example, of a solenoid having a 
plunger 67 linked to the rocking arm 65, and is pivotally mounted on a 
fixed part 69 of the machine. By feeding an operating signal to the 
actuator 68, the blocking means 60 can therefore be moved either to the 
disengaged position shown in FIG. 2 in which it releases the gap 64 and is 
withdrawn far into the slotted guides 61, or it can be moved to its 
working position as shown in FIG. 3. In this working position, the end of 
the blocking means 60 associated with the needles extends both through the 
slot 64 and also through the wedge-shaped gap 49 that follows in the 
direction of rotation of the teasing cylinder. Due to the fact that the 
blocking means 60 extends through the slot 64, the open needle hooks 4 are 
blocked such that, ahead of the comb-in zone 11, fibers released from the 
card teasing hooks 14 are not combed into the needle hooks 4. Since the 
blocking plate extends into the wedge-shaped gap 49, however, the fiber 
tufts 57 combed into the needle hooks are protected against the teasing 
hooks 14 regardless of the fiber length selected in the individual case, 
and therefore they cannot be attacked by the teasing hooks and pulled out 
of the needle hooks. The blocking means 60 is thus a component of a 
protective means for preserving the fiber tufts 57 combed into the needles 
3 situated in the comb-in zone. At the same time the section covering the 
needle hooks and the section covering the fiber tufts 57, of the blocking 
means 60, could also be separated from one another and connected to 
different actuating means. Also, the rocking arm 65 is shown much shorter 
than it would be, and actually it is about as long as is necessary to 
achieve the desired length of movement of the blocking element 60. 
FIG. 5 shows a control apparatus for the circular knitting machine 
described in conjunction with FIGS. 1 to 4. It contains a power supply 71 
which provides current to all electronic and electromagnetic components, 
especially a controller 72 for the servo motor 41 and a controller 73 for 
the drive 34 of the circular knitting machine, and is also connected to a 
main switch 74. The controller 72 for the servo motor has an input 
connected to the power supply 71 and an output connected to the servo 
motor. Another input is connected to a starter switch 75, a switch 76 
being inserted into the line running to the latter, which can be brought 
by an actuator 77 from its normal, closed position to an open position. 
Another input of the controller 72 is connected to two switches 78 and 79 
which are in series. Switch 78 can be brought by an actuator 80 from its 
normal, closed position to an open position, while switch 79 can be 
brought by an actuator 81 from its normal, open position to a closed 
position. An additional input of the controller 72 is connected to the 
moving contact of a switch 82 which can be turned to any of three solid 
contacts which are connected each with a potentiometer 83. The other 
terminals of this potentiometer 83 are connected to three fixed contacts 
of an additional switch 84, which also has a contact that can be moved to 
one of the three fixed contacts. The switches 82 and 84 and the 
potentiometer 83 form a preselection circuit and serve to provide the 
controller 72 with, for example, three individually selectable rotatory 
speeds for the rotation of the servo motor 41 in the forward direction. 
Another input of the controller 72 is finally connected by a line 85 to 
the moving contact 86 of a switch whose three fixed contacts are connected 
by potentiometer 87 to three fixed contacts of a switch 88 such that, with 
the switches 86 and 88 and the potentiometers 87, three individually 
presettable rotatory speeds, for example, can be selected for the servo 
motor 41 when it runs in the reverse direction. 
The starter switch 75 is connected by an adjustable timer 89 to the fixed 
contact of a switch 90. The moving contact of this switch 90 is connected 
to the controller 73 for the motor 34 of the needle cylinder. This motor 
34 has an indicator in the form of a tachometer generator 91 which, in the 
usual manner, consists of a dynamo which provides at its output a voltage 
which is proportional to the rotatory speed of the motor 34. The output of 
a reference standard 92 is connected to an additional input of the 
controller 73. The reference standard 92 contains an ordinary amplifier 93 
to whose one input a potentiometer 94 is connected and whose output is 
connected to the moving contact of a switch 95 whose two fixed contacts 
are connected each through a resistance 96-97 to the input of an 
additional amplifier 98. The output of the tachometer generator 91 is 
connected to the input of a comparator 100 to whose output is connected an 
actuator 101 which serves to shift the moving contact of switch 95 from 
the one to the other fixed contact of this switch. 
The controller furthermore contains a manually operated stop switch 102 
and, if necessary, at least one automatically operating stop switch 103, 
for example in the form of a shutoff commonly used in circular knitting 
machines, which is tripped in the event of thread breakage, needle 
breakage or the like. The two switches 102 and 103 are connected to an 
actuator 104 which serves to shift the normally closed switch 90 to an 
open position. The actuator 81 is connected to the output of a comparator 
105 whose input is connected to the output of the tachometer generator 91. 
Otherwise, the free terminals of switches 75, 84, 88, and 102 and 103 of 
the potentiometer 94 are connected to the power supply or to some other 
appropriate source of current or voltage. 
Lastly, the controller of FIG. 5 has two additional comparators 106 and 
107. The output of comparator 106 is connected on the one hand to one 
input of each of the actuators 55 and 68 and on the other hand to the 
actuator 77 of switch 76, while the comparator 107 is connected on the one 
hand with an additional input of each of actuators 55 and 68 and on the 
other hand to the actuator 80 of switch 78. The inputs of the comparators 
106 and 107 are connected to the output of the tachometer generator 91. 
The switches 76, 78, 79, 90 and 95 and their associated actuators 77, 80, 
81, 101 and 104 can consist of purely electronic components, but also they 
can be electromechanical components, e.g., reed contacts operated by 
relays. 
In the control system described, the following adjustments are possible: 
Depending on the type of fiber to be used, which can vary in regard to 
fiber length, titer or the like, first the ganged pairs of switches 82-84 
and 86-88 can be set such that the servo motor 41, whether turning forward 
or backward, will run at a rotatory speed determined according to the type 
of fiber. The rotatory speeds required in each case are to be determined 
in preliminary tests with the fibers to be used, and if necessary can be 
recorded in tables. Experiments have shown that, in most practical cases, 
three different rotatory speeds forward and three in reverse will suffice, 
and that these speeds can be associated with fiber lengths up to 25 mm, 
between 25 and 40 mm, and 40 to 80 mm of length. This gives the advantage 
that the potentiometers 83 and 87 can be set one time, and, when the type 
of fiber changes, only switch pairs 82-84 and 86-88 will need to be 
changed. Furthermore, the timer 89 can be adjusted to the time desired in 
the particular case. The timer 89 determines how long a time the servo 
motor 41 is to be energized before turning on the motor 34 of the knitting 
machine. Here, again, the adjustment can be determined on the basis of the 
type of fiber and recorded in tables. It would also be possible to provide 
several fixed timers, each associated with one type of fiber. It is 
desirable, however, to adjust the timer to a sufficiently long period of 
time to permit a sufficiently long preliminary feed by the servo motor 41 
for all of the types of fibers that are involved. An additional adjustment 
is offered by the potentiometer 94 which is associated with the reference 
standard 92. The reference standard 92 establishes through the controller 
73 the accelerations with which the speed of the needle cylinder is to be 
increased during start-up, and on the other hand it establishes the 
maximum rotatory speed, i.e., the production speed which the needle 
cylinder is to reach. The production speed can be adjusted with the 
potentiometer 94. Lastly, it is possible to set the rotatory speed of the 
motor 33 driving the teasing cylinder 10, through an additional 
potentiometer not shown, or through a switch. 
The control system described operates as follows: 
By operating the main switch 74, first the motor 33 driving the teasing 
cylinder 10 and the power supply are turned on to supply power to the 
control system. By means of an interlock, which is not shown, provision 
can be made such that operation of the starter switch 75 will not be 
possible until the teasing cylinder has reached its nominal rotatory 
speed. The blocking means 60 and the ejection flap 50 are during this time 
in the working position represented in FIG. 3, while the needle cylinder 2 
is stopped and the different switches assume the positions seen in FIG. 5. 
The result is that, in the area of the entrance opening 16, the teasing 
cylinder 10 teases out the part of the condensed sliver 8 that extends 
into the range of action of the teasing hooks 14. The fibers pulled out of 
the sliver in this manner are accelerated out of the teasing hooks 14 in 
the area of the releasing section 19, but, on account of the extended 
blocking means 60, are unable to enter into the needle hooks 4. 
Consequently, these fibers are transported on over the needlehooks and 
then ejected through the open ejection flap 50. At the same time, the 
blocking means 60 prevents fiber tufts 57, which have already been laid 
into the needle hooks in a preceding knitting action, from being pulled 
out of the needle hooks by the suction of the teasing cylinder 10 or by 
the interference of the teasing hooks. The fiber tufts 57 already laid in 
the needles that are in the comb-in zone therefore are retained, so that 
thick and thin areas are prevented when the needle cylinder starts up. 
After the teasing cylinder 10 has reached its nominal speed, the starter 
switch 75 is closed, thereby delivering power through the closed switch 76 
and the controller 72 to the servo motor 41 to make the latter run in the 
forward direction at a speed depending on the position of the switch pair 
82-84 and the potentiometer 83. As a result, the feed rolls 7 are set in 
rotation and the portion of the fiber sliver partially torn apart by the 
teasing cylinder 10 is replaced at the entry 16. Thus, a higher rate of 
feed of fibers than the synchronous rate is fed to the comb-in zone 11, 
because in conventional high-pile knitting machines the feed cylinders are 
at rest as long as the needle cylinder is at rest. This process, which is 
known as forefeeding the fibers and is intended for the prevention of thin 
areas caused by start-up, likewise takes place when the needle cylinder is 
stopped, and lasts until the timer 89 emits a signal. When this signal 
appears, the sliver or sheet of fibers situated on the teasing cylinder 10 
is again built up to the extent that is necessary for the knitting 
procedure that follows. 
The signal from the timer 89 runs through the switch 90 and the controller 
73 to start the motor 34 driving the needle cylinder, preferably with an 
initial, comparatively great start-up acceleration established by the 
reference standard 92. This start-up acceleration results when the moving 
contact of switch 95 is connected to the resistance 97 which, with the 
capacitor 99, forms an RC circuit and results in a voltage rise at the 
output of the amplifier 98 corresponding to the first section of the U/t 
curve represented in a block 108 of the reference standard 92. The needle 
cylinder thus begins to rotate, and the tachometer generator 91 delivers a 
voltage proportional to the momentary speed of the motor 34, which is fed 
to the comparators 106 and 100 which were activated in the start-up cycle. 
When this voltage attains a relatively low value detected by the 
comparator 106, the comparator 106 emits a signal which is delivered to 
the actuator 77 which then opens the switch 76 thus turning off the servo 
motor 41. At the same time the output signal from the comparator 106 is 
delivered to the actuators 55 and 68, thereby shifting the ejection flap 
50 and the blocking means 60 to the disengaged position seen in FIG. 2. As 
a result of the shutting off of the servo motor 41, the feed cylinders 7 
are then driven at a speed determined only by the motor 34, i.e., a speed 
synchronous with the needle cylinder speed. The displacement of the 
ejection flap 50 and of the blocking means 60, however, brings it about 
that the needle hooks 4 are now released and the ejection opening 58 is 
closed, so that all of the fibers fed by the teasing cylinder 10 are 
placed in the needles 3. The synchronous rotation of the feed cylinders 7 
now assures that the necessary amount of fibers will be fed. The voltage 
at which the comparator 106 emits its signal is best selected such that, 
when the needle cylinder is started, the lowest possible number of needles 
will enter the comb-in zone before the blocking means 60 is withdrawn, so 
as to prevent failure of delivery of fibers to a plurality of adjacent 
needles. In practical use, the voltage of the tachometer generator 91 can 
be selected at such a low level that no more than one needle will pass 
through the comb-in zone without picking up fibers. 
The rotatory speed of the needle cylinder now increases with the 
acceleration preset by the reference standard 92. It can happen that some 
thin areas will occur in the goods on start-up, which are apparently due 
to the fact that, if excessively great accelerations occur, the 
synchronous rotatory speed of the feed cylinders 7 is not sufficient. To 
prevent such thin areas a changeover to a lower acceleration rate will be 
made at a needle cylinder speed to be determined by experiment. This is 
accomplished as follows: when the voltage of the tachometer generator 91 
reaches a certain level, corresponding for example to the voltage a in 
block 108, the comparator 100 will emit a signal and thus by means of 
actuator 101 will shift the moving contact of switch 95. Consequently, the 
needle cylinder will then be accelerated at a second, lower rate until it 
has reached its preset production speed and is maintained at this speed by 
the controller 73. The lower speed is established in this case by the RC 
circuit formed by the resistor 96 and the capacitor 99. 
If the knitting machine is to be shut off, either the stop switch 102 or 
the stop switch 103 is operated automatically. When this happens, the 
comparators 105 and 107 which were inactive during the start cycle are 
activated and at the same time the two comparators 106 and 100 which were 
active during the start cycle are rendered inactive. Furthermore, a signal 
is delivered to the actuator 104 causing it to open the switch 90, thus 
shutting off the motor 34 and at the same time actuating a magnetic brake 
to stop the needle cylinder. 
The needle cylinder is then braked according to the amount of braking power 
applied, while the teasing cylinder 10 continues to run at an unchanged 
speed so that fibers are fed into all needles running through the comb-in 
zone until the needle cylinder comes to a full stop. Since the feed 
cylinders 7 are also braked during the stop cycle, the wire hooks 14 in 
the teasing cylinder 10 now tear a higher percentage of fibers from the 
fiber sliver projecting into the entry opening 16 than is necessary for 
the attainment of a uniform knit fabric. The thickened areas thus caused 
are avoided in accordance with the invention in that, upon the attainment 
of a preselected needle cylinder speed, the feed cylinders are rotated 
more slowly than the synchronous speed in order thereby to compensate the 
oversupply of fibers produced by the teasing cylinder. To this end, the 
comparator 105 is set to a preselected voltage, so that, upon the 
attainment of this voltage at the output of the tachometer generator 91, 
it will emit a signal which will operate the actuator 81 to close switch 
79 and thus turn on the servo motor 41, through line 85 and the controller 
72, in the reverse direction at a speed predetermined by the setting of 
the switch pairs 86-88 and the potentiometer 87. Thus the rate of fiber 
feed in the area of the comb-in zone 11 is reduced to such a level that 
thick areas in the fabric caused by the shutoff cycle are prevented. The 
rotatory speed at which the servo motor 41 is to be turned on must be 
determined by experiment. It can also happen that the servo motor must be 
turned on when the switches 102 and 103 are actuated, in which case the 
comparator 105 is to be set to a value just below the production speed or 
it is to be turned on directly by the switches 102 and 103. 
To avoid thick areas from forming in the start cycle, the comparator 107 
puts out a signal shortly before the needle cylinder stops; this signal is 
delivered on the one hand to the actuators 55 and 68 and on the other hand 
it turns off the servo motor through the actuator 80 and the switch 78 
which it opens, so that, when the needle cylinder comes to a stop, the 
feed cylinders will stop also. The feeding of the output signal to the 
actuators 55 and 68 has the result of shifting the ejection flap 50 and 
the blocking means 60 back to their working position shown in FIG. 3, and 
therefore fibers which might be fed by the still rotating teasing cylinder 
10 while the needle cylinder is stopped are not introduced in the needles 
3, which are also stopped, but are removed through the ejection opening 
58. Thus no more fibers are introduced even into those needles 3 which 
enter the comb-in zone just before the needle cylinder stops than 
corresponds to the desired fiber density. At the same time the output 
voltage of the tachometer generator 91 at which the comparator 107 emits 
its signal can be selected so as to be so low that only one more needle 
enters the comb-in zone after the blocking means has been moved forward. 
Furthermore, provision is made through the output signal of the comparator 
107 so that all switches will then reassume the positions shown in FIG. 5. 
The invention is not limited to the described embodiment, which can be 
modified in many ways. For example, it is possible to provide, instead of 
the blocking means 60, a covering flap suspended pivotally from the side 
walls of the shroud 15 and bearing at its end adjacent the needles 3 a 
plate which, when the covering flap turns, is introduced into a gap 109 
(FIG. 3) between the shroud 15 and the front sides of the needles for the 
purpose of blocking their open hooks 4. This covering flap could also be 
controlled by a solenoid actuator. Instead of the fiber guide plate 47 
containing the pivoted ejection valve 50, a fiber guide plate consisting 
of one piece and displaceable radially and, if desired, also 
circumferentially of the teasing cylinder 10, can be provided, or a 
pivoting fiber guide plate simultaneously forming the ejection flap. Such 
a fiber guide plate would have the advantage that, between the blocking 
means 60 in its active position and the end of the fiber plate associated 
with it, a sufficiently wide air aspirating gap could be formed, which 
would improve the air flow needed for the ejection of fibers. Furthermore, 
it is possible to provide, instead of the solenoids 55 and 56, other 
actuating means, e.g., hydraulic or pneumatic cylinder-and-piston systems. 
The ejection flap 50 can be disposed at a point between the entry opening 
16 and the comb-in zone 11 in the direction of rotation of the teasing 
cylinder 10, and it can be connected, if desired, to an aspirator. In this 
manner shut-down thickenings can be prevented without requiring a blocking 
means for the needles, because all of the fibers entering the hooks 14 of 
the teasing cylinder 10 while the needle cylinder is stopped would be 
removed through the ejection opening before reaching the comb-in zone 11. 
Furthermore, the pivoting ejection flap 50 can be replaced by a sliding 
fiber guide plate, which offers advantages especially with regard to 
access to the parts of the card situated in back of the needles. The 
over-proportional braking of the feed cylinders 7 performed by means of 
the servo motor 41 could also be accomplished by means of a 
remote-controlled clutch (U.S. Pat. No. 3,709,002) by temporarily 
disengaging this clutch during the stop cycles or withdrawing it 
pulse-wise, in order thereby to interrupt at least momentarily the 
synchronous running of the feeding cylinders. 
As seen in FIG. 5, it is possible with a small number of different, preset 
speeds of the servo motor 41 to prevent any and all thick and thin areas. 
There is also the possibility of replacing the preselecting means formed 
by the switch pairs 82-84 and 86-88 and potentiometers 83 and 87, with 
programmed preselecting means which constantly change the speeds of the 
servo motors on the basis of a predetermined schedule, e.g., a curve, 
individually attuned to the type of fiber used in the individual case. 
Accordingly, all of the rest of the circuit elements can be adapted 
individually to the type of fiber. Provision can furthermore be made for 
momentarily interrupting the synchronism between the feed means and the 
needle cylinder, not only in the starting and stopping cycles, but also in 
the event of any other abrupt speed changes. A momentary interruption of 
the synchronism can also be brought about by varying the distance between 
the feed means, e.g., the two feed cylinders 7, and the teasing cylinder 
10, or by varying the rotatory speed of the teasing cylinder 10, because 
the synchronism between the feeding of fibers to the teasing cylinder and 
the fiber transfer to the comb-in zone resulting in the required fiber 
density is also affected by these factors. 
Those parts of the guard means which serve for the prevention of the 
disengagement of fiber tufts already held on the needles can also be 
modified. It is mentioned only by way of example that, to this end, a) the 
teasing cylinder could be stopped upon every stop and restart and then 
started up again or at least it could be braked down, b) the conditions of 
flow in back of the comb-in zone could be arranged such that the fiber 
tufts cannot come in contact with the tips of the teasing hooks 14 when 
the needle cylinder is stopped, c) the distance between the teasing 
cylinder and the needles and/or the fiber guide plate could be increased 
while the needle cylinder is stopped, d) teasing hooks could be used 
which, when the needle cylinder is stopped, are retracted into the teasing 
cylinder 10, and e) compressed air or a vacuum could be produced by using 
teasing cylinders or fiber guide surfaces having screen-like surfaces, in 
order to keep the fiber tufts away from the card hooks 14. 
The above-described controller can accordingly also be used in creep rate 
operation or for so-called tip operation, in which the needle cylinder is 
turned each time only briefly by a few needle spaces. In order even here 
to assure the preselected fiber density it can be necessary to further 
reduce the speed of the teasing cylinder or the feed rate of the fibers to 
the teasing cylinder or to sustain the synchronism in the operation of 
braking down. 
Instead of the feed means represented, feed means can be provided which 
have at least one feed cylinder and a fiber guide plate associated with it 
(U.S. Pat. No. 3,968,662). 
The invention has just been described in conjunction with the example of a 
single knitting system of a circular knitting machine. In circular 
knitting machines with a plurality of system, the described card 6 can be 
associated with each system. At the same time it is possible to drive a 
plurality of teasing cylinders with a single motor. Also, the term 
circular knitting machines is to include circular hosiery machines.