Note: Descriptions are shown in the official language in which they were submitted.
081~90
Background of the Invention
The sliver method of knitting high pile fabrics
produces a "fly loss". Such term, as used in the art, refers
to all sliver fibers which are not incorporated into a sliver
knit high pile fabric during knitting.
Fly loss occurs because the slivers or rovings used
in knitting high pile fabrics are composed of relatively fine,
short, discrete fibers, which are especially susceptible to
diffusion during handling. In sliver knitting, an unavoidable,
relatively significant percentage of the fibers is lost as a
sliver is transferred from its source of supply to the usual
fiber carding and transfer mechanism, and thence to the needles
of the knitting machine. Wheelock `~.S. patent 2,993,351 and
~ ~t U.S. patent 3,72~,872 illustrate apparatus designed for
use with sliver knitters to recover fiber wasteage through fly
loss.
The knitting of sliver high pile fabrics requires
that a certain minimum quantity of fibers be in each sliver
feeding system at all times, in order to produce fabrics of
uniform pile density. This minimum quantity of fibers is
defined as the "charge" of fibers in the feeding system
necessary to meet the demand of the needles for fibers. The
charge is composed of base fibers which tend to nestle within,
and be retained by, the wire coverings of the main cylinder
and doffer of a sliver feed system, plus the fibers in transit
to the needles. The transit fibers of the charge ride upon
the base fibers, as they travel to the needles.
To produce pile fabrics of uniform pile density,
the charge of fibers in a sliver feeding system must be main-
tained at a constant level. This presentæ no serious problemin the knitting of non-patterned work, since fly loss is
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rel~tively constant. The rate of sliver input by sliver feed
rolls is easily adjusted to feed sliver at a rate sufficient to
produce fabric of selected pile density, while compensating for
fly loss. In the knitting of non-patterned sliver high pile
fabrics, it is possible to ignore fly loss altogether, and
produce satisfactory fabric of uniform density. The finished ~-
fabric simply is of somewhat less pile density than would be
the case if the fly loss either had been compensated for, or
had not occurred.
However, in the knitting of multi-color patterned sliver
high pile fabrics, which require selective feeding of various ~ ;
slivers either at variable rates or intermittently, a new
problem arises. In knitting such fabrics, the sliver feed
rolls cease feeding sliver altogther when needles are not
selected. Where only relatively few needles are selected,
thereby diminishing the demand of the needles for fibers, the
rate at which sliver is fed by the sliver feed rolls to the
main cylinder and doffer may fall below the rate of fly loss.
In such situations, the fly loss may create charge loss, i.e.
may cause depletion of the fiber charge on the doffer and main
cylinder in the sliver feeding system, thereby creating faults
in the fabric being knitted. Charge loss results from fly loss
and either the non-selection of needles or the minimal
selection of needles. Charge loss may be defined as fly loss
extending over a period of time, when no additional fibers are
added to the sliver feeding system, or insufficient fibers are
added to compensate for fly loss.
In knitting multi-color sliver pile fabrics having
intricate designs, it is essential, in order to obtain uniform
pile density, to harmonize the rates at which selected slivers
are fed by the doffer to selected needles with the demand of
the needles for fibers, in accordance with the fabric pattern
selected. When, during the knitting of multi-color patterned
fabrics, feeding of a sliver is stopped completely, or is
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reduced to a very low feeding rate, fly loss may cause partial
or even complete depletion of the charge fibers from the
sliver feeding system and particularly from the rapidly rotating
doffer.
Where no sliver fibers are fed to a card for a sus-
tained period, the doffer and even the main cylinder might
empty completely of charge fibers through fly loss. If this
occurs, the first needles eventually selected to receive fibers
at such doffer may take no fibers at all, causing a fault in
the fabric.
If, due to reduced needle selection, sliver fibers
are fed at a minimal rate to the doffer, the rate of feed may
be less than the rate of fly loss, thereby reducing the fiber
charge in the card. As a result, the few needles selected may
draw an insufficient supply of fibers, causing a fault in the
fabric.
Usually, fly loss presentsno problem when a large
number of needles are selected to rake sliver fibers from a
s~sfem
B doffer, because the level of the charge in the sliver feeding~
remains constant. It is only when relatively.few needles are
selected, or none are selected, and the rate of sliver feeding
varies accordingly, that the problem arises.
Summary of the Invention
The primary object of this invention is to provide a
new and improved method of knitting multi-color~ patterned
sliver high pile fabrics on circular knitting machines, which
compensates for charge loss during knitting.
A further object of the invention is to provide a
new and improved method for feeding sliver to a high pile
fabric circular knitting machine in which the rate of sliver
feed is proportioned automatically to harmonize with the
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demand of selected needles for sliver fibers, while compensating
for charge loss resulting from fly loss and the non-selection
or minimal selection of needles.
A further object is to provide a new and improved method for
knitting a patterned multi-color sliver high pile fabric on a
multi-feed circular knitting machine whereby a minimum quantity
of sliver fibers are maintained on each doffer during knitting,
to ensure that sufficient quantities of pile fibers are avail-
able at all times to meet the demand of selected needles for
fibers, to ensure the production of high quality fabric ofuniform pile density.
A further object is to provide a new and improved method
for knitting sliver high pile fabrics having intricate designs
on multi-feed circular knitting machines whereby the rate of
feed of each sliver to the needles is proportionate to the
number of needles selected according to the design, the speed
of rotation of the circle of needles, the selected pile density
of the fabric and the rate of fly loss, but not less than a
rate sufficient to compensate for any depletion of the charge
fibers in the sliver feeding system.
In accordance with an aspect of the invention there is
provided a method for maintaining constant the fiber charge~in
a sliver feeding system during knitting of multi-color patterned
sliver high pile fabric on a multi-feed circular knitting
machine, to provide patterned high pile fabric of substantially
uniform pile density throughout the pattern, said sliver feeding
system including a rotatable doffer for delivering fibers to
the needles and, a pair of selectively rotatable sliver feed
rolls and characterized by continuously rotating the sliver
feed rolls 14, 16 at selectively variable rates of speed to
advance sliver fibers to the doffer 10 at rates equal to any
selected fabric patterning rate plus a rate approximating the
rate of charge loss resulting from fly loss and the non-
selection or the minimal selection of needles.
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Descr'ipt'ion' of'th'e Views o'f the Drawing
Fig. 1 is a schematic diagram illustrating an
electronically controlled multi-feed sliver high pile fiber
circular knitting machine incorporating a preferred embodi-
ment of this invention.
Fig. 2 is a schematic block diagram illustrating
functionally the data transfer electronic circuitry for con-
trolling the rates of feed of the sliver feed rolls of each
sliver feeding mechanism of the knitting machine.
Fig. 3 is a fragmentary, partially schematic view
in perspective, showing one of the sliver feeding mechanisms
or cards of the machine, utilizing a stepping motor to drive
its sliver feed rolls.
Fig. 4 is a fragmentary, schematic block diagram
showing the data transfer electronic circuitry of Fig. 2
incorporating-suppLemental-control-circuitry-for the-sliver
feed rolls to Qperate the same continuously, at selected
minimum rates of speed, to provide selected minimum rates of
sliver feed to compensatF for charge loss.
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Detailed Description of the Invention
The improvement of the present invention may be
incorporated into any known type of sliver high pile fabric
circular knitting machine such as, for example, the sliver
knitters illustrated in the following United States patents:
Hill No. 3,010,297, Hill No. 3,014,355, Wiesinger ~o.
3,427,829, Schmidt No. 3,563,058, Brandt et al No. 3,709,002
and Christiansen et al No. 4,007,607. At the present time,
the best mode contemplated for carrying out the invention is
to incorporate it into the electronically controlled multi-
feed sliver high pile fabric circular knitting machine dis-
closed in Christiansen et al U.S. patent 4,007,607. The
disclosure of that patent is incorporated herein by reference.
Referring to the drawing, in Fig. 1 there is shown
schematically in top plan the knitting head of the machine M
of Christiansen et al patent 4,007,607 having a plurality of
independent latch needles (not shown) mounted in a circle in
a conventional needle cylinder (also not shown), with capacity
for selected reciprocal movement. The cylinder is rotatable
in the direction of the curved arrow.
-
In the embodiment shown, the machine M is provided
with 12 sliver feeding stations, Fl to F2 inclusive, spaced
at uniform intervals around the needle cylinder. Each such
station includes a card C (Fig. 3) having the usual wire-clothed
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rotatable doffer lO and main cylinder 12, and a pair of
rotatable sliver feed rolls 14, 16. The latter trans~er a
roving or sliver (not shown) from a source of supply via
the main cylinder 12 to the doffer 10 for delivery to selected
needles. The feed rolls are driven by a stepping motor 20
through a conventional timing belt drive 22 and conventional
gearing 24. Disposed at each sliver feeding station Fl-Fl2,
in advance of its card C, are needles selecting mechanisms
Sl to S12, respectively, each of which is composed of a
plurality of individual electromagnetic needle selecting
actuators of the type illustrated in Christiansen ~.S. patent
3,896,639.
~he electronic control apparatus for selecting
needles includes a main memory 30, a buffer memory 32 and
needle control logic circuitry 34, the latter being connected
electrically by conventional circuitry to each separate
electromagnetic actuator of the needle selecting mechanisms
Sl to S12 inclusive. A power amplifier 36 is interposed in
the circuit connecting each needle selecting actuator to the
needle control logic circuitry 34 In the interest of brevity,
only one circuit is shown in Fig. 1 connecting the needle
control logic 34 to an electromagnetic needle selecting
actuator (at Sl).
Data is transferred from the main memory 30 to the
electromagnetic actuators in response to signals generated
by an absolute encoder 38 geared to the knitting machine M.
Encoder 38 generates a train of pulses, proportional to the
speed of rotation of the needle cylinder, to enable sequentially
the several actuators of the successive needle selecting
mechanisms Sl-S12.
, _ _ . . . . ... . ...
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~08149~
The electronic control apparatus for the knitting
machine M also includes control circuitry for regulating
continuously the speed of rotation of the stepping m~tors 20
associated with each of the 12 cards C, to control selectively
the rate of sliver feed at each station Fl-F12. The electronic
control for the stepping motors includes card feed rate logic
circuitry 40, connected electrically to each stepping motor 20
by separate circuitry which includes decoding logic circuitry
42 and a power amplifier 44. The decoding logic 42 decodes
the pulse train from the card feed rate logic circuitry 40 to
the input form required by the stepping motors 20.
For the purpose of illustration, only one circuit is
shown in Fig. 1 connecting the card feed rate logic 40 to one
of the stepping motors 20 at a sliver feeding station (Fl).
It is to be understood that a separate circuit, each provided
with its own decoding logic 42 and power amplifier 44, connects
each stepping motor 20 of each card C to the card feed rate
logic circuitry. To ensure that the sliver feeding rates of
the 12 cards C are at all times proportional to the speed of
rotation of the needle cylinder, the card feed rate logic
circuitry 40 is clocked by a signal directly proportional to
the rotative speed of the needle cylinder. The pulse output
of the absolute encoder 38 may be utilized to provide the
needle clock input to' the card feed rate logic.
The card feed rate logic circuitry 40 is illustrated
schematically in Fig. 2 by the portion of the functional block
diagram interposed between the buffer mem,ory 32 and the stepping
motor decoding logic 42. As explained in Christiansen et al
U.S. patent 4,007,607 aforesaid, the logic depicted in Fig. 2
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renders unnecessary incorporating into the main mem~ry 30
sliver feed control data, for controlling the rates at which
sliver is fed at each sliver feeding station Fl-F12. The
electronic control system depicted in Fig. 2 calculates
continuously and accurately the necessary sliver feeding
rates using the needle selection pattern data stored by the
memory 30. The calculations are carried out by a data
calculating and transfer circuit, which includes the buffer
memory 32 for the temporary storage of needle selection
pattern data, counter 50, multiplier 52, divider 54, rate
mul~iplier 56 and buffer shift register 60.
In addition to using needle selection pattern data
retrieved from the memory 30, the data calculating and transfer
electronic circuit also incorporates into its calculations,
from the input of clock pulses at the "ma" number, the selected
speed of rotation of the needle cylinder. It also incorporates
into its calculations the selected pile density of the fabric
being knit, from a set of thumbwheel switches (not shown),
the selected setting of which is applied to rate multiplier 58
interposed between rate multiplier 56 and buffer shift register
60.
The sliver feeding rate data obtained from the second
rate multiplier 58 is stored in the buffer shift register 60,
to which also are applied the "ma" clock pulses previously
25 referred to. The data stored in the buffer shift register 60,
at the appropriate time, is transferred to one of the active
shift registers Rl-R12 connected by suitable circuitry to one
of the stepping motors for one of the twelve cards.
Fig. 2 illustrates an arrangement by which rate data
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~081~90
is transferred from the buffer shift register 60 to the active
shift register Rl, which controls the stepping motor 20 of
the card C at sliver feeding station Fl. The active shift
register Rl is clocked by the pulse output of the encoder 38,
which is proportional to the speed of rotation of the needle
cylinder. The data output of the active shift register Rl
is combined with this clock, as indicated by the "and" function
block 62. The resulting pulse train is decoded by the stepping
motor decoding logic 42 and amplified by the power amplifier
lQ 44, t~ drive the stepping motor 20 at the speed necessary for
card C.to feed sliver at a selected rate in harmony with the
fabric pattern selected. The result is to provide a card
with continuously controlled sliver feed roll drive means,
calculated to ensure that the sliver input to the machine
harmonizes with the demand of selected needles for fibers,
the speed of rotation of the circle of needles and the desired
pile density of the fabric.
As explainea previously,--charge loss may arise and-
create faults in multi-color patterned sliver knit fabrics
where the feed of a sliver temporarily is stopped completely,
due to non-selection of needles or is reduced to a very low
rate because relatively few needles are selected to receive
fibers. To compensate for this, and maintain constant the
fiber charge in a sliver feeding system, the p esent invention
provides for the continuous rotation of the sliver feed rolls
14, 16, at selectively adjustable minimum rates of rotation,
calculated to feed sliver at minimum rates approximating the
rate of fly loss, preferably at a rate equal to or slightly
less than the rate of fly loss. Arranging for the sliver feed
rolls 14, 16 to rotate continuously at selected minimum speeds
of rotation to compensate for charge loss, ensures that a
sufficient quantity or charge of fibers is maintained on the
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doffer 10 at all times during knitting to meet the demand of
selected needles for fibers, and to avoid faults in the pile
density of the fabric.
The additional logic or control circuitry required
to obtain such selected minimum rates of sliver feed is
illustrated in Fig. 4. It comprises a divider 70, rate
multiplier 72, anti-coincidence circuit 74 and "or" gate 76.
The control logic to obtain the desired selected minimum
rates of sliver feed is interposed in the basic data calcu-
lating and transfer electronic circuit between rate multiplier58 and buffer shift register 60.
By way of illustration, it will be assumed that not
more than 93 of each 100 data bits (i.e. discrete commands for
needles to take sliver or to welt) transferred from rate
multiplier 58 and stored in the buffer shift register 60, will
be binary or logic "l's" (i.e. needle commands to take sliver).
The sliver therefore is advanced at its selected maximum
feeding rate by the feed rolls 14, 16 when 93 of each 100 data
bits entered on the shift register 60 are logic "l's". This
arrange~ent provides for the possibility of increasing the
speed of the stepping motor 20 by 973, or approximately 7.5%
beyond the selected maximum speed, resulting in a corresponding
increase in the sliver feed rate.
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The train of clock pulses "ma" applied to the buffer
shift register 60 supplies one pulse for each data bit, i.e.
for each logic "1" or "0", entered in the register. As
explained in Christiansen et al U.S. patent 4,007,607 afore-
said, in the clock "ma" the designation "m" is a selectedconstant comprising a scaling factor and the designation "a"
denotes the data bits or commands for a selected number of
needles "a". In the example given, "a" = 100 data bits.
Since the number of pulses of the buffer shift register clock
0 "ma" is proportional to the maximum sliver feed rate (i.e. 93
logic "l's" randomly evenly distributed for each 100 data bi~s),
a pulse train which represents any fraction of the maximum
sliver feed rate may be obtained by dividing the "ma" clock
.,;
; pulses by any appropriate number "n". The divisor "n" is a
; 5 number which, when divided into "ma", produces a quotient
; preferably and normally, but not necessarily, equal to or less
, .
than the difference between the data bits "a" of the clock
...
"ma" and the maximum logic "l's" per "a" data bits (in the
example given, the difference is 100 - 93 = 7).
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~08~490
In the modified electronic circuit of Fig. 4, the
divider 70 and the rate multiplier 72 are utilized to divide
by "n" the buffer shift register clock "ma", to provide the
minimum sliver feed rate data. The divided clock is entered
into the buffer shift register 60 as additional data by
adding it via "or" gate 76 to the sliver feed rate data
obtained from the data calculating and transfer circuit inter-
posed between main memory 30 and buffer shift register 60.
The minimum sliver feed rate data, obtained from the divided
buffer shift register clock, must be added to the register
60 when the data entered from the rate multiplier 58 is a
logic "0". The anti-coincidence circuit 74, connected to
the rate multiplier 58 and the "or" gate 76 ensures this, by
detecting the presence of a logic "0" data bit entering the
buffer shift register 60 from the rate multiplier 58.
The invention thus permits continuous feeding of
sliver by the sliver feed rolls 14, 16 to the main-cylinder-
12 and doffer 10, at selectively variable rates of sliver
feed, such rates being proportionate to the number of needles
selected, the speed of rotation of the circle of needles, the
selected pile density of the fabric and the rate of fly loss,
to maintain the charge of fibers in the sliver feeding system
at a constant level at all times.
In practice, a minimum rate of sliver feed of 1%
of the maximum rate of sliver feed may be sufficient to
compensate for any depletion of the charge. However, since
fly loss will occur at various rates, under various knitting
conditions, it is desirahle to provide means to adjust easily
and selectively the compensating minimum rate of sliver feed.
For this purpose, a high-low divisor switch (not shown) pro-
viding for two basic speed ranges, m or 2m, furnishes a
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selected input to the divider 70. Additionally, a second
thumbwheel switch (not shown~, graduated from 0 through 9,
with input to the rate multiplier 72, is provided for adjust-
ing further the minimum sliver feeding rates through either
of the two speed range settings provided by the divisor
switch aforesaid.
The arrangement illustrated in Fig. 4 ensures that,
at all times during knitting, when needles are selected to
rake fibers from the doffer, the sliver is fed at a rate
adequate to provide sufficient quantities of fibers on the
doffer to meet the fiber demand of selected needles, as
- required by the fabric pattern, and to compensate for charge
loss resulting from fly loss and the non-selection or minimal
selection of needles. Thus, there is provided a new and
: 15 improved method of sliver knitting, whereby the rate of
;, sliver delivery to the doffer at all times is carefully con-
^ trolled, so that it is proportionate to the number of needles
.~, selected according to the design, the rotation of the needles,
.,.: .
the pile density of the fabric and the rate of fly loss, to
~ 20 maintain the charge of fibers in a sliver feeding system at
,~ a constant level at all times. The method of the invention
ensures operating the sliver feed rolls at selected minimum
'~ speeds necessary to advance sliver to the doffer at rates
",'~'F sufficient to compensate for any depletion of the charge.
.~ 25 In the claims which follow, the terms
(1) "selected fabric patterning rate"
t~ shall indicate a rate of sliver input to a
. .
sliver feeding system in harmony with the
demand of selected needles for fibers, accord-
~' 30 ing to a selected fabric pattern, and
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108~490
(2) "minimal selection of needles"
shall indicate the selection of so few
needles that the demand of the needles for
fibers, according to a selected fabric
pattern, is less than the rate of fly loss
from the sliver feeding system.
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