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Патент USA US3088185

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May 7, 1963
3,088,1 75
3 Sheets-Sheet 1
Filed Jan. 10, 1958
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May 7, 1963
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BY M/wdímûí, MUM
May 7, 1963
Filed Jan. 10, 1958
5 Sheets-Sheet 3
Patented May 7„ 1963
Akira Aoki, 1-94 Ohmino 64m, Tomioka-cho, Higashi
Sumiyoshi-ku, Osaka, Japan
Filed Jan. 10, 1958, Ser. N0. 708,264
2 Claims. (Ci. 19-2¢‘i0)
This invention relates to new and useful improvement-s
in »an «automatic level control system for product sliver
weight. For the control of product sliver counts in cotton
ing drawings wherein Va is the surface speed of feed
roller A, Vb surface speed of `delivery roller B, and C
the sensing point, the surface speed Va or Vb in the feed
back `control -system is changed according to the variation
of the sliver weight from the standard spinning level.
In this feed back system we must consider the time
constant of the sensing device, controller and Icontrolled
plant »as well as the disturbance Vcaused by the variation
of feed `sliver’s thickness and the noise caused by draft.
Therefore a special device Ito maintain stability of control
and ability of control in the control system will be nec
and rayon spinning, the `so-called quality control system
FIG. 2 shows an example of variation of sliver weight
is applied. At the present stage the X-R chart system is
which corresponds to the fiber `density in the cross sec
widely used for .the control of product sliver counts in a
drawing operation. In this case, however, the causes of 15 tional area of the sliver. In this ligure, P and Q are
arbitrary time points and t the time la-g of point Q to point
getting out of control are in most cases not clear, so the
P. Now by indicating increase in the trend of variation
common operation to maintain the lspinning level is to
of sliver weight as (-}-) and decrease (_) it would be
change the draft change gear according to the information
from the X-R chart. This operation does not mean the
elimination of the `so-called assignable cause but merely
means the adjusting of the spinning level. Therefore,
over-action due to misjudgment of control chart as well
possible to calculate the correlation coefficient r of the
sign of variation of sliver weight as a 'function of time
lag l.
FIG. 3 shows an example of a sliver Uster diagram of
sliver. For this variation, the short term variation may
be eliminated by use of the moving average. By “mov
Now, if we desire to vcontrol correctly the weight of
product sliver, it will he useful to increase the frequency 25 ing average” is meant the average weight of a length of
sliver which moves past a fixed point in a given time. It
of sampling. In extremity, the sampling interval will be
is known, as evidenced by the diagram shown in FIG. 12
zero. It means 100% .sampling or screening. In this
that the frequency of variations of sliver Weight is very
case all lthe product will be `consumed for weighing.
high. The time over which the .average is taken is long
However, if it will Ibe possible to measure the thickness
enough for several individual changes in weight to take
of sliver which corresponds to the über density in cross
place, but is relatively- shor-t compared to the time in
sectional area of the product sliver =b_y some electronic
which the entire sliver takes .to pass the point in question.
means, mechanical means or pneumatic means and to
The average thus varies substantially continually.
change the draft percentage according to variance from
FIG. 4 shows the correlogram in respect to r and t
the standard spinning level, this kind of vcontrol method 35
and the »ter-m of moving average n, as applied to the fore
will truly be an .automatic level control system for prod
going example in FIG. 3. From the information given
uct sliver weight.
in FIG. 4, it can be clearly said that the wider the range
The characteristic features, objects and advantages of
of moving average the wider the range of time lag t
this invention will become more apparent from the fol
lowing description made with reference to the accom 40 which shows the statistically significant value of r. There
fore this indicates the possibility of estimating the input
panying drawings.
in draft control -by the feed back system, and :also it will
In the drawings:
lessen the error due to mischange of draft resulting from
FIG. l is a diagrammatic view of two pairs of drafting
time .lag of the control action.
FIG. 5 shows lan example of a system for determining
FIG. 2 is a graph showing variation in sliver weight 45
moving average in which applied to ythe sensing device
over a period of time;
is an air micrometer. In this ligure, air tank 3 connects
FIG. 3 is a sample Uster diagram for a sliver;
to air tubes 2 land 4, and the capacity of said tank 3 is
FIG. 4 is a graph of correlation coeñicient Vs. time `for
as misaction due to sampling error could not lbe avoided.
readily changeable. ’Ihe action of this air tank 3 is just
a series of moving averages;
FIG. 5 is a diagrammatic view of a means for sensin-g 50 like a condenser tube; in other words, it smooths out the
moving average;
FIG. 6 is a graph of moving average vs. time showing
the limits at which control starts;
FIG. 7 is a circuit diagram of the control for the draft
ing roll drive;
output »of the air micrometer nozzle. Hence the output
of tank 3 is the moving average of -the output of air mi
crometer nozzle l.
However, stability of control will not be satisfactory
55 with this feed back draft control system with the moving
average apparatus, because of the time lag of the control
action. In other words, it `will not be possible to avoid
the hunting of draft change in this system, which can be
FIG. 8b is an enlarged diagrammatic view of a por
noted vfrom the statistical information in FIG. 4.
tion of FIG. 8a;
FIG. 6 shows the fundamental idea for securing cori
FIG. 9 is a diagrammatic layout of a drafting mecha 60
trol stability. The desired weight of the sliver is repre
nism with a control system according to the present i11
FIG. 8a is a diagrammatic view of the entire sensing
system according to the present invention;
sented by the O line. On either side of this line is a neu
tral zone within which no control is exercised. The
range of this neutral zone is 2b which consists of ian
65 upper limit 4and lower limit at the position b on both sides
of the center line. The ycontrol action starts at this upper
FIG. ll is a diagrammatic view of sa modification of
the sliver sensing means according to the present inven
and lower control limit, and the range of this neutral zone
FIG. 10 is a graph of the coeiiicient of variation in
percent vs. the length of sliver for various control con
tion; and
FIG. l2 is a graph of sliver Weight in percent vs. length
should be adjusted according to the type of sliver de
Actual control laction operates as follows: If the
70 input reaches the control limit, the output of the sensing
device is transmitted to the controller through »a transfer
In the draft unit shown in FIG. l of the accompany
device, and -after the constant time lag the control action
of sliver for a no control and a control condition respec
will start. It will therefore be impossible to cont-rol the
level of the product sliver inside fthe neutral zone. Actu
ally, vthe `control ran-ge of the level of weight of the prod
8, the electric circuit of switch 5 is closed and the output
of the sensing device is transmitted to the pilot motor 12
as (-|-) and draft control action to increase the product
sliver weight, which is explained in connection with FIG.
9, is initiated. If end 11 contacts the contact 9', the opposite
output (_) is transmitted to the pilot motor 12 and draft
control action to decrease the product sliver weight, which
is explained in connection with FIG. 9, is initiated. The
uct sliver is wider than that of the neutral zone. In this
ligure the actual control range is indicated yby the upper
and lo-wer expected control limit. This range 2a is wider
than 2b. The relation of 2a and 2b will be determinable
by 4the st-atistical information of input variation and by the
transference and time `constant of this automatic control
pilot motor 12 will not operate as long as the front end
system. By means of this neutral zone system in the feed 10 11 of rod 10 does not come in contact with contacts 8 and
back draft control system, control stability will be main
9. Therefore, the neutral zone described with reference to
FIG. 6 corresponds to the angle of oscillation 0’.
FIG. 9 shows a plan for the control apparatus and the
This .neutral zone system like the moving average sys
tem forms a basis `for satisfactorily effecting automatic
controlled plant. In this ligure, A1 is the 2nd roller, A2
control of Weight level of product sliver.
15 the 3rd roller, A3 the back roller, B the delivery roller,
FIG. 8a shows an example of automatic level control
D the calender roller, while 23 is a fast and loose pulley
system for a 4 roll drafting System. In this figure, A1
on a main shaft, 24 and 25 are pulleys on sheaves. 27
and 28 are pulleys or sheaves or sprocket wheels, and |12
indicates the 2nd roller, A2 the 3rd roller, A3 the back
is the pilot motor. A variable speed drive 26 is provided
roller, B the -delivery roller, S the product sliver, 1 the
air micrometer nozzle, and D the calender roller. A 20 having input shaft 26a, output `shaft 26b and control shaft
27a on which pulley 27 is mounted. The rotating speed
compressor 15 pumps air into high pressure air tank
16 from whence air passes through air cleaner 17 to air
of input shaft 26a which is driven through pulleys 23,
24 and 25, is a constant speed, but the rotating speed
tank 18. Pressure in tank 18 remains constant and is
fed through constant pressure Vvalves 19 and 20 and pipe
of output shaft 26b is varied 4from that of input shaft 26a
21 to pressure adjusting valve 22. Pipe 2 joins the air 25 by means of the action of pulley 27 through pulley 28
micrometer nozzle 1 to a moving average air tank 3, »and
which action is directed by pilot motor 12. In other
pressure adjusting valve 22 joins pipe 2. YPivoted rod 10
words, the pilot motor 12 serves to adjust the ratio of
is oscillated around pivot 7 by the movement of rod 13
rotating speed between input shaft 26a and output shaft
which is moved by bellows 14 to which moving average
26b of the variable speed drive 26 to control the product
air tank 3 is connected. Rod 10 has a slit 10’ therein 30 sliver weight. The transmission of rotation between pulley
so that the pin on the end of rod 13 may slide freely in
24 and pulleys 25, 27 and 28, 30 and 31 is performed
the slit.
by chain drives or belt drives. The variable speed drive
FIG. 8b shows on an enlarged scale bellows 14, con
is a conventional type, so thel rotation of pulley 27 changes
necting rod 13, rod 10 andV contacts 8, 9 of the neutral
the ratio of rotating speed between the input shaft 26a
zone circuit which is shown in FIG. 7.
35 and output shaft 26b of the variable speed drive. Pulleys,
In operation, airrcompressed by compressor 15 is puri
sheavesor sprocket wheels 30, 31 and gears 32 are con
iied by air cleaner 17 and its pressure is stabilized by
nected to drive the feed rollers F, and gears 29 are con
high pressure air tank »16 and connecting tank 18, and a
nected to drive rollers A1_A3. Therefore the surface
constant pressure of air is obtained by conventional
speed of delivery roller B, roller B being driven from the
constant pressure valves l19 and 20. The air passes 40 main shaft, is constant and that of A1, A2, A3 and F is
through valve 20, connecting pipe 21 and pressure ad
changed at the same ratio by the action of pilot motor 12.
justing valve 22, and is divided so as to move in two
The (-{-) direction of control action means increasing
directions, i.e. to nozzle 1 which forms the air micrometer
the product sliver weight and the (_) direction of con
and to tank 3 of a moving average determining means
trol action means decreasing the product sliver weight.
and bellows 14. The nozzle 1 is of special construction,
The (+) or (_) direction of control action is performed
i.e. the air inlet of nozzle 1 is perpendicular to the path 45 by the following control system.
of the sliver and the pressure in pipe 2 is elevated by
When pilot motor 12 rotates in the (~|-) direction, con
the sliver in passing through nozzle 1. The variationV of
trol shaft 27a of variable speed drive 26 rotates in the
pressure is proportionate to the variation of thickness of
(-|-) direction, being driven through sprocket wheels 27,
sliver which passes through nozzle 1 and may be varied 50 28 by the chain drive of pilot motor 12, the output of
by a suitable setting of valve 22. Therefore the variation
variable speed drive 26 is increased in the (-1-) direction;
of pressure which corresponds to the variation of thick
in other words, the rotating speed of the output shaft
ness of sliver passing through nozzle 1 is transformed ap
26h of variable speed drive 26 increases at a constantly
proximately to the valuel of the moving average by tank 3.
changing ratio, which ratio should be designed at the
The value of this moving average causes a variation of 55 initial stage of designing this control equipment, to the
pressure in bellows 14. The expansion and contraction
constant rotating -speed of input shaft 26a` of variable
of bellows 14 is thus governed by the output of tank 3,
speed drive 26. By this operation, the notating speeds of
and the Value of this deformation of bellows 14 is pro
roller A1, A2, A3 and F are increased at the same con
portional to the value of the output of tank 3.
stantly changing ratio as that of output shaft 26b of varia
The role of tank 3 in producing an output proportional 60 ble speed drive 26. Since the rotating speed of roller B
to the moving average has been explained above, but
is constant, the draft ratio between the roller A1 and B
an explanation concerning the effect of the capacity of
decreases, the weight of produced sliver S continues to
tank 3 is necessary. A change in capacity of said tank
increase up to the breaking of the electric circuit which
will produce a change in the range of the moving average,
is described in connection with FIG. 7 and IFIG. 8b. By
i.e. the lager the capacity of the tank the smoother will
this control operation, the average weight of produced
be the transmission of the output of the tank to bel~
sliver is controlled inside the expected lower control limit
lows 14.
which is described in connection with FIG. 6.
The deformation of bellows 14 oscillates rod 10 around
On the contrary, if the weight of produced sliver should
the center of oscillation 7. The front end of rod 10
reach the starting limit of upper control action which is
completes the electric circuit through one of two elec 70 described in connection with FIG. 6, i.e. if the end 11
trodes (see FIG. 7)' the distance between these electrodes
of rod 10 touches contact 9, the output of the electric
corresponding to the angle of oscillation of rod 10,
circuit is in the (_) direction. Therefore the pilot motor
i.e. 0’. In FIG. 7, rod 10 oscillates around the pivot 7
12 rotates in the (_) direction, and the oppositel con
as a result of the output of the sensing device. If the
trol action is performed in the same manner as the control
front end 11 of rod 10 comes in contact with contact 75 action in the (-{-) direction. By this control action the
draft ratio between roller A1 and B is increased, and the
weight of produced sliver S continues to decrease up to
the breaking of the electric circuit of FIG. 7 and FIG. 8b.
By this control operation, the average weight of produced
sliver is controlled inside the expected upper control limit
which is described in connection with FIG. 6.
FIG. 10 shows the variance length curve of product
sliver weight. One can readily recognize the excellent
a sensing means on the delivery side of the drafting mecha
nism for continually sensing the product sliver weight,
means for averaging the output of said sensing means, said
means being connected to said sensing means, an off-on
control having two on positions and an olf position there
between, and a control means connected to the variable
speed driving means for the drafting mechanism, said
oñ-on control being connected to said control means for
causing said control means to increase the speed of the
control eífect by this automatic control system. This
example was taken on the product sliver from No. 2 10 variable speed driving means when the oiï-on control
drawing frame, and is the result of test on one delivery.
is in one on position and to decrease the `speed of the
In the present operation of cotton and rayon spinning,
variable speed driving means when the off-on control is in
the other on position, said off-on control being connected
to said means for averaging and being actuated by said
control of only sliver on a frame will not be wanted for
economical reasons. As explained previously, the statisti
cal quality control system is being applied at the present 15 means to one of the on positions when the variation of
the averaged output of the sensing means from a predeter
stage. For this reason, automatic control for the aver
age counts of product sliver of a drawing frame will be
useful to the quality control program of mills. For
this purpose a single automatic average apparatus for the
output of all delivery rollers on an entire frame is de
sirable. FIG. 1l shows an example of this equipment.
In this figure, air tank 3’ performs the automatic trans
ference of the moving average and average of output of
each sliver delivery by the frame. The position for in
mined average sliver product weight is an amount greater
than a predetermined amount.
2. Apparatus for controlling product sliver weight pro
duced by drafting rolls comprised of feed rolls, intermedi
ate rolls and delivery rolls and having a variable speed
driving mechanism driving said feed rolls and intermediate
rolls, said apparatus comprising an air micrometer on the
delivery side of said drafting rolls, an air tank to which
stalling this air tank is the same as the position of air 25 said air micrometer is connected, a source of constant
pressure air connected to said air micrometer and to said
tank 3 in FIG. 8.
tank, a bellows connected to said tank, a pivoted arm
FIG. 12 is an example showing results obtained by this
one end of which is actuated by said bellows, two contacts
automatic control system.
spaced from each other on opposite sides of a middle
As described above, the present invention is an auto
matic control system for product sliver weight by use 30 position of the other end of said pivoted arm, an electric
motor controlling the speed of the variable speed driving
of a feed back system characterized in that, taking into
mechanism, and two electric circuits, one of which con
consideration the time constant, the disturbance caused
tains one of `said two contacts and said arm and ener
by the variation of feed sliver thickness and noise caused
gizing said electric motor to drive it in one direction, and
by draft, it eiîects automatic control by leaving variation
such as inch units as they are and adjusting automatically 35 the other of which contains the other of said two contacts
and said arm and energizes said electric motor to drive
medium or larger variation, for example over 1/2 yd.
it in the other direction.
while confirming the control effects thereof. Not only is
this invention altogether diñerent in its way of thinking
References Cited in the file of this patent
from heretofore known level adjusting methods by open
circuit, but it is a useful invention that is entirely new 40
in its mechanism, easy to operate and effective.
Mutter _______________ __ June 18, 1940
What I claim is:
Lewis ________________ _.. Oct. 24, 1944
l. Apparatus for controlling product sliver weight pro
duced by a multi-roll drafting mechanism having feed
rolls, intermediate rolls and delivery rolls and having a 45
variable speed driving means driving the feed rolls and
intermediate rolls of said drafting mechanism, comprising
Richardson ____________ __ Sept. 3, 1946
Martin ______________ __ Sept. 10, 1957
Lewis et al ____________ __ July 22, 1958
Locher _______________ __ Aug. 30, 1960
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