BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a warp-beaming machine
which winds a warp sheet around a take-up beam at a desired
take-up tension by applying a force of a take-up roller to
the warp sheet, the warp sheet being obtained by combining
one or more yarn sheets unwound from respective sectional
beams, and more specifically relates to a technique for
setting a force applied to the take-up roller to an optimum
value on the basis of the relationship between feeding
tensions applied to the sectional beams and the desired
take-up tension.
2. Description of the Related Art
In a typical warp-beaming machine, yarn sheets are
unwound from several to more than ten sectional beams and
are combined into a single warp sheet, and the warp sheet is
wound around a single take-up beam to obtain a warp beam.
In such a warp-beaming machine, it is important to manage a
tension applied to the warp sheet which is wound around the
take-up beam, that is, a take-up tension, and various
tension control devices have been proposed. For example, a
tension control device is known in which each of the
sectional beams is provided with a feeding-tension-applying
unit including an actuator, such as a powder brake, for
applying a feeding tension to the corresponding yarn sheet
and the rotational speed of the take-up beam is controlled
such that the warp sheet moves at a predetermined moving
speed. All of the actuators generate the same feeding
tension and the warp sheet receives a correcting tension
corresponding to the sum of the feeding tensions of the
sectional beams from a torque-applying unit connected to a
take-up roller, so that a predetermined take-up tension is
applied to the warp sheet. In this tension control device,
each of the feeding tensions applied to the sectional beams
is controlled by an open-loop control system and the take-up
tension is controlled by a closed-loop control system.
Accordingly, the overall control device has high accuracy
and is easily obtained.
When T1 is the sum of the feeding tensions of the
sectional beams, T3 is the predetermined take-up tension,
and T2 is the correcting tension applied to the take-up
roller, T2 is calculated as T2 = T3 - T1 from the force
balance. Accordingly, the correcting tension T2 must be set
as accurate a bias value as possible for the take-up roller
in the closed-loop system. However, when powder brakes are
used as actuators, generated braking forces greatly vary
with time. Therefore, in order to set an accurate bias
value before starting the operation of the warp-beaming
machine, an operator must start a preliminary steady-state
operation, put the control system into an open-loop state to
stop the tension correction, and manually set the bias value
for the take-up roller while monitoring the take-up tension
so that the detected take-up tension becomes the same as the
predetermined take-up tension (refer to, for example,
Japanese Unexamined Patent Application Publication No. 64-69468,
pages 1 to 7).
As described above, the preliminary steady-state
operation must be performed for setting an accurate bias
value. When the preliminary steady-state operation for
setting the bias value is being performed, the warp sheet is
wound at a tension largely different from the desired take-up
tension since the bias value is adjusted manually. The
difference from the desired take-up tension leads to
breakage of warp yarns and failure in shedding motion in a
weaving process performed afterwards, and thus the operation
of a loom is adversely affected. In addition, the warp
sheet wound while the bias value is being set is relatively
long, such as several tens to several hundreds of meters,
and is discarded since it would adversely affect the
operation of the loom, and thus the warp sheet is wasted.
In addition, a so-called beam fracture or the like easily
occurs in the surface of the take-up beam when the bias
value is being set, and this adversely affects the warp
yarns wound around the take-up beam afterwards. In such a
case, the quality of the warp beam is further degraded.
These problems also occur in warp-beaming machines which do
not have the above-described closed-loop system (that is,
the tension control device) for controlling the take-up
tension.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to
provide a warp-beaming machine which winds a warp sheet
around a take-up beam at a desired take-up tension by
applying a force of a take-up roller to the warp sheet, the
warp sheet being obtained by combining one or more yarn
sheets unwound from respective sectional beams, wherein the
force of the take-up roller, that is, a bias value, is
quickly and accurately set without performing the
preliminary steady-state operation for manual setting.
According to a first aspect of the present invention, a
warp-beaming machine includes one or more rotatably
supported sectional beams, each sectional beam having a yarn
sheet wound around the sectional beam; one or more feeding-tension-applying
units provided for the respective sectional
beams, each feeding-tension-applying unit applying a force
to the corresponding sectional beam on the basis of a
feeding tension set for the sectional beam and thereby
applying the feeding tension to the corresponding yarn
sheet; a take-up roller which comes into contact with a warp
sheet obtained by combining the yarn sheets unwound from the
respective sectional beams; a setting unit for outputting a
bias value; and a torque-applying unit for applying a
rotational torque corresponding to the bias value to the
take-up roller. The feeding-tension-applying units and the
torque-applying unit are all activated while a beaming
operation for winding the warp sheet around a take-up beam
is being performed, and the setting unit receives a desired
take-up tension which is to be applied to the warp sheet
when the warp sheet is wound around the take-up beam and the
feeding tensions for the respective sectional beams in
advance and outputs the result of subtraction of the sum of
the feeding tensions from the desired take-up tension to the
torque-applying unit as the bias value.
According to the first aspect of the present invention,
the setting unit receives the desired take-up tension and
the feeding tensions for the respective sectional beams and
outputs the difference T2 obtained by subtracting the sum T1
of the feeding tensions for the respective sectional beams
from the desired take-up tension T3 as the bias value.
Therefore, the optimum bias value is quickly set without
performing the preliminary steady-state operation, which is
required in the known warp-beaming machine. Since the bias
value is set before starting the operation of the warp-beaming
machine, the warp sheet is wound at a desired take-up
tension from the start. Therefore, the quality of the
warp beam is increased compared to the known warp-beaming
machine, and the quality degradation of the warp beam and
the waste of the warp yarns are prevented.
Preferably, the desired take-up tension is maintained
while the steady-state operation is being performed. More
specifically, according to a second aspect of the present
invention, a warp-beaming machine includes one or more
rotatably supported sectional beams, each sectional beam
having a yarn sheet wound around the sectional beam; one or
more feeding-tension-applying units provided for the
respective sectional beams, each feeding-tension-applying
unit applying a force to the corresponding sectional beam on
the basis of a feeding tension set for the sectional beam
and thereby applying the feeding tension to the
corresponding yarn sheet; a take-up roller which comes into
contact with a warp sheet obtained by combining the yarn
sheets unwound from the respective sectional beams; a
tension sensor for detecting a warp tension at a position
downstream of the take-up roller; a setting unit for
outputting a bias value; and a torque-applying unit for
applying a rotational torque corresponding to the bias value
to the take-up roller. The feeding-tension-applying units
and the torque-applying unit are all activated while a
beaming operation for winding the warp sheet around a take-up
beam is being performed. In addition, the setting unit
receives a desired take-up tension which is to be applied to
the warp sheet when the warp sheet is wound around the take-up
beam and the feeding tensions for the respective
sectional beams in advance and outputs the result of
subtraction of the sum of the feeding tensions from the
desired take-up tension to the torque-applying unit as the
bias value, and the torque-applying unit receives the
desired take-up tension and the warp tension from the
tension sensor and corrects the bias value by adding an
amount of correction corresponding to the difference between
the warp tension and the desired take-up tension.
According to the second aspect of the present invention,
the setting unit outputs the difference T2 obtained by
subtracting the sum T1 of the feeding tensions for the
respective sectional beams from the desired take-up tension
T3 as the bias value. Therefore, similar to the first
aspect, the optimum bias value is quickly set without
performing the preliminary steady-state operation, which is
required in the known warp-beaming machine. In addition,
the torque-applying unit outputs the sum of the bias value
and the amount of correction corresponding to the difference
between the detected warp tension and the desired take-up
tension as the corrected bias value and applies a torque
corresponding to the corrected bias value to the take-up
roller. Accordingly, the warp tension in a region between
the take-up roller and the take-up beam, that is, the take-up
tension, is continuously maintained at the desired take-up
tension T3.
In the above-described first and second aspects of the
present invention, each of the feeding-tension-applying
units provided for the respective sectional beams may
include an actuator for applying a braking torque to the
corresponding sectional beam, a force detector for detecting
the force applied to the sectional beam, and a torque
control unit for controlling the braking torque generated by
the actuator on the basis of the feeding tension and the
force detected by the force detector. The actuator is not
limited as long as it generates a force in accordance with
an electrical signal. For example, a powder brake is
preferably used as the actuator. However, the present
invention is not limited to this, and a rotational actuator,
such as a torque motor, may also be used. In the case in
which the powder brake is used, even if the braking force is
reduced with time due to wear of magnetic powder, such as
iron powder, contained in the powder brake, the reduction in
the braking force is detected and the torque control unit
controls the braking torque so as to maintain the feeding
tension. Accordingly, the feeding tension is continuously
maintained at the set value. Therefore, the actual force
applied to each of the sectional beams is prevented from
being reduced to below the set value due to, for example,
wear of the powder, and therefore the warp sheet is
prevented from being wound around the take-up beam at a
take-up tension lower than the desired take-up tension.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a diagram showing the overall structure of a
warp-beaming machine according to the present invention;
Fig. 2 is a diagram showing a peripheral region of a
sectional beam shown in Fig. 1;
Fig. 3 is a block diagram of the main part of a control
device for controlling the warp-beaming machine; and
Fig. 4 is a block diagram of a correcting-torque
command unit shown in Fig. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of the present invention will be
described below with reference to the drawings. Fig. 1
shows an example of a warp-beaming machine 10. A base plate
13 is placed in front of a take-up device 11, and n
sectional beams 19a1 to 19an, where n is an integer of one or
more, are rotatably supported by beam stands 15a1 to 15an,
respectively, which are arranged on the base plate 13 along
a moving direction of warp yarns 31.
The beam stands 15a1 to 15an are arranged on a single
horizontal line such that the height of the axes of the
sectional beams 19a1 to 19an gradually increases as the
distance from the take-up device 11 increases. In addition,
guide rollers 17a1 to 17an extending parallel to the axes of
the sectional beams 19a1 to 19an are disposed near the
sectional beams 19a1 to 19an, respectively. Similar to the
beam stands 15a1 to 15an, the guide rollers 17a1 to 17an are
supported by supporting members (not shown) which are
arranged such that the height of the axes of the guide
rollers 17a1 to 17an gradually increases as the distance from
the take-up device 11 increases. The sectional beams 19a1 to
19an are connected to powder brakes 33a1 to 33an, respectively,
which apply braking torques to the rotations of the
sectional beams 19a1 to 19an. This will be described in more
detail below. Sheets of warp yarns 31, that is, yarn sheets,
are unwound from the sectional beams 19a1 to 19an, are guided
upward to the respective guide rollers 17a1 to 17an, and are
then guided into the take-up device 11. When the axes of
the beam stands 15a1 to 15an are suitably positioned, the
yarn sheets unwound from their respective sectional beams
19a1 to 19an can be directly guided to the take-up device 11
such that they do not come into contact with each other. In
such a case, the guide rollers 17a1 to 17an may be omitted.
Fig. 2 shows the structure of each of the powder brakes
and a peripheral region thereof, the powder brakes applying
braking forces to the rotations of the respective sectional
beams 19a1 to 19an. More specifically, in each sectional
beam 19, a flange 35 is provided on each end of a beam shaft
36, and a sheet of multiple warp yarns 31, that is, a yarn
sheet, is wound between the flanges 35 and is guided toward
the take-up device 11. Each sectional beam 19 (19a1 to 19an)
is provided with a roll diameter sensor 39 (39a1 to 39an) for
detecting the diameter of the roll of the yarn sheet. The
beam shaft 36 is rotatably supported by a pair of beam
stands 15 at both ends thereof with metal parts (not shown)
interposed therebetween. In addition, a beam gear 37 is
formed integrally with the beam shaft 36 such that they have
a common rotational axis.
A powder brake 40 basically includes a shaft 42, a
first driving member 44a, a second driving member 44b, an
excitation coil 45a, a stator 45b, and a driven member 46,
all of which are contained in a case 41.
The case 41 has a cylindrical shape with end faces, and
a shaft 42, which functions as an output shaft, extends out
from the case 41 through one of the end faces. A driven
gear 38 is formed integrally with the shaft 42 at the outer
end of the shaft 42 such that they have a common axis, and
the shaft 42 is rotatably supported by a bearing 43 in the
case 41. In addition, the first driving member 44a is fixed
to the shaft 42 at the inner end of the shaft 42 such that
they have a common rotational axis. The first driving
member 44a and the second driving member 44b are composed of
a magnetic material, such as iron, and have a plate-like
shape (a disc-like shape). In addition, the first driving
member 44a and the second driving member 44b are combined
together such that they have a common axis and that the
peripheral portions thereof face each other with an annular
non-magnetic member (not shown) interposed therebetween.
Accordingly, a driving member unit 44 obtained by combining
the driving members 44a and 44b has a bracket shape in cross
section with a magnetic gap provided therein, and a space is
provided between surfaces of the driving members 44a and 44b
which face each other. The driven member 46 is positioned
such that a projection 46a provided thereon extends radially
along the surfaces of the driving members 44a and 44b in the
space between the driving members 44a and 44b. The
projection 46a of the driven member 46 is positioned such
that a gap 47b is provided between the end of the projection
46a and an inner surface of the driving member unit 44 at a
position corresponding to the magnetic gap between the
driving members 44a and 44b, and a base plate of the driven
member 46 is fixed to the case 41 such that it cannot rotate.
In addition, a space 47a is provided between the projection
46a and the driving member unit 44, and iron powder or the
like is enclosed in the space 47a. The stator 45b has a
ring-like shape and is disposed outside the driving member
unit 44 such that it embraces the excitation coil 45a with a
magnetic gap provided at a position corresponding to the
magnetic gap provided in the driving member unit 44.
In the above-described powder brake 40, which is well
known in the art, when a direct current is applied to the
excitation coil 45a, a magnetic flux which passes through
the stator 45b, the driving member unit 44, and the
projection 46a is generated and the powder collects in the
gap 47b. Accordingly, the driving member unit 44 and the
driven member 46 are connected with each other by the powder
collecting therebetween, and a braking torque corresponding
to the supplied current is generated in the driving member
44, that is, in the shaft 42.
The case 41 of the powder brake 40 is attached to the
corresponding beam stand 15 with a stay 48 and a load cell
49 provided therebetween, and the load cell 49 outputs an
electrical signal representing a force applied. In addition,
the driven gear 38, which is formed integrally with the
shaft 42, meshes with the beam gear 37. The load cell 49
detects a reaction force applied to the case 41 in the
rotating direction, in other words, the braking torque
applied to the corresponding sectional beam by the powder
brake 40. The powder brake 40 shown in Fig. 2 is provided
for each of the sectional beams 19a1 to 19an shown in Fig. 1.
As shown in Fig. 1, the take-up device 11 includes a
plurality of rollers, each of which is rotatably supported
by a pair of frames (not shown) at both ends thereof. More
specifically, the take-up device 11 includes a first pushing
roller 21, a take-up roller 23, a second pushing roller 25,
a tension roller 27, and a detachably attached take-up beam
29. An auxiliary motor 24 which generates a predetermined
rotational torque is connected to the take-up roller 23, and
the first pushing roller 21 and the second pushing roller 25
are arranged such that the sheet of warp yarns 31 obtained
by combining the yarn sheets, that is, a warp sheet, is
pressed between the take-up roller 23 and the first pushing
roller 21 and between the take-up roller 23 and the second
pushing roller 25. The tension roller 27 is provided with a
tension sensor 28 which detects the tension of the warp
yarns 31 on the tension roller 27 and generates an
electrical tension signal T. The take-up beam 29 is
connected to a take-up motor 30 by a connecting mechanism
(not shown) and is provided with a roll diameter sensor 34
which detects the roll diameter of the take-up beam 29. The
warp yarns 31 guided toward the take-up device 11
successively pass through a zigzag reed 32 and the above-described
rollers and are wound around the take-up beam 29.
The take-up device 11 is provided with a control device
50 for controlling the auxiliary motor 24, the take-up motor
30, etc. The control device 50 receives the tension signal
T from the tension sensor 28 and a roll-diameter signal d0
from the roll diameter sensor 34, and transmits outputs to
the powder brakes 33a1 to 33an, the auxiliary motor 24, and
the take-up motor 30.
Fig. 3 is a block diagram showing the inner structure
of the control device 50. The control device 50 basically
includes a take-up control unit 51 for driving the take-up
motor 30, a feeding-torque command unit 55 for supplying an
excitation current to each of the powder brakes 33a1 to 33an,
a correcting-torque command unit 60 for supplying a current
for driving the auxiliary motor 24, and a setting unit 80
for outputting yarn-speed command signals and torque command
signals to the above-described units.
The setting unit 80 includes a plurality of setters 80a,
80b, 80c1 to 80cn, and 80d, each setter being composed of a
variable resistor or the like and setting a value, roll-diameter
correctors 81a1 to 81an, and a calculator 82. The
setters 80a and 80b set a low speed SL1 and a high speed SH1,
respectively, as moving speeds of the warp sheet during the
operation. The low speed SL1 is used when the operation
starts, and the high speed SH1 is used in the steady-state
operation. Speed signals SL1 and SH1 representing the low
and high speeds, respectively, are supplied to the take-up
control unit 51.
The setter 80d sets a desired take-up tension TS1 for
when the warp sheet is wound around the take-up beam 29, and
a take-up tension signal TS1 representing the desired take-up
tension is supplied to the calculator 82 and the correcting-torque
command unit 60.
The setters 80c1 to 80cn set feeding tensions 80c1 to
80cn for the sectional beams 19a1 to 19an, respectively, and
feeding-tension signals 80c1 to 80cn representing the feeding
tensions are respectively input to the roll-diameter
correctors 81a1 to 81an, which are provided for the
respective sectional beams, at one of two input terminals.
In addition, roll-diameter signals d1 to dn from the
respective sectional beams are input to the roll-diameter
correctors 81a1 to 81an at the other one of the two input
terminals. The roll-diameter correctors 81a1 to 81an correct
the received feeding tensions 80c1 to 80cn on the basis of
the roll diameters d1 to dn input thereto, and output
feeding-tension signals TSO1 to TSOn representing the
corrected feeding tensions 81c1 to 81cn to the calculator 82
and the feeding-torque command unit 55.
The calculator 82 calculates a correcting torque to be
applied to the sheet of warp yarns 31 by the take-up roller
23, that is, a bias value TS2, on the basis of the values
input thereto, and outputs a bias value signal TS2
representing the bias value to the correcting-torque command
unit 60. The bias value TS2 is obtained by subtracting the
sum of the feeding tensions 81c1 to 81cn of the respective
sectional beams from the desired take-up tension TS1 as
follows:
TS2 = TS1 - (81c1 + 82c2 + ... + 81cn)
Before starting the operation of the warp-beaming
machine, an operator sets the above-described values into
the setting unit 80 in accordance with a setting data sheet
or the like provided for each production lot. Since the
values are set before the operation of the warp-beaming
machine starts, the calculator 82 can immediately calculate
an optimum bias value TS2 from Equation (1) and output the
result to the correcting-torque command unit 60. In place
of the above-described setters, the setting unit 80 may also
include a setter having a touch panel or the like with which
the values can be individually input and displayed. The
calculator 82 may be a hardware circuit (a combination of an
adder circuit and a subtractor circuit) or a computer.
Alternatively, when a setting device having a touch panel is
used as described above, a calculating function of a
microcomputer or a soft-ware installed in the setting device
may be used for obtaining the output.
The take-up control unit 51 includes a speed signal
generator 52 and a drive circuit 53. The speed signal
generator 52 receives the low-speed signal SL1 and the highspeed
signal SH1 from the setting unit 80, the roll-diameter
signal d0 from the roll diameter sensor 34, and a drive
signal S2 from a sequence control device 84. When the speed
signal generator 52 receives the drive signal S2, it refers
to the roll-diameter signal d0 and outputs a speed command
signal SP1 representing a yarn speed determined on the basis
of the low and high speeds SL1 and SH1 to the drive circuit
53. More specifically, when the drive signal S2 is input,
the speed signal generator 52 sets a speed command to the
low speed SL1, increases the speed command until it reaches
the high speed SH1, and then maintains the speed command at
the high speed SH1. The drive circuit 53 receives a
rotational speed signal SP0 from a speed detector 54
connected to the take-up motor 30. In addition, the drive
circuit 53 includes a known speed control circuit for
driving the take-up motor 30 at a speed corresponding to the
speed command signal input thereto, and supplies electric
power required for driving the take-up motor 30.
The feeding-torque command unit 55 includes control
circuits 56a1 to 56an provided for the respective powder
brakes 33a1 to 33an, each control unit serving as a torque
control unit. The control circuits 56a1 to 56an include
torque signal generators 57a1 to 57an and drive circuits 58a1
to 58an, respectively. The torque signal generators 57a1 to
57an respectively receive the feeding-tension signals TSO1 to
Tson from the setting unit 80 and force signals qs1 to qsn
from load cells 49a1 to 49an. In addition, the torque signal
generators 57a1 to 57an also receive an operation preparation
signal S1 from the sequence control device 84. When the
torque signal generators 57a1 to 57an receive the operation
preparation signal S1, they refer to the force signals qs1 to
qsn input as feedback signals and output torque command
signals i1 to in for generating torques corresponding to the
feeding tension signals TSO1 to TSOn (feeding tensions 81c1 to
81cn) to the drive circuits 58a1 to 58an, respectively. The
drive circuits 58a1 to 58an supply direct currents (DC
currents) corresponding to the torque commands i1 to in to
the excitation coils of the powder brakes 33a1 to 33an,
respectively. Accordingly, the powder brakes 33a1 to 33an
apply braking torques corresponding to the feeding tension
signals TSO1 to TSOn (feeding tensions 81c1 to 81cn) to the
sectional beams 19a1 to 19an, respectively, via the shafts 42.
Thus, the feeding-torque command unit 55 controls the
currents applied to the excitation coils on the basis of
forces (braking torques) detected by the load cells 49a1 to
49an, so that the torques corresponding to the feeding
tension signals TSO1 to TSOn (feeding tensions 81c1 to 81cn)
are generated by the powder brakes. As a result, even if
the powder is worn as the operation proceeds, the braking
torques corresponding to the feeding tensions can be
generated. Although the powder brakes are used as actuators
for generating the braking torques in the present embodiment,
rotational actuators which generate rotational torques, such
as torque motors, may also be used in place of the powder
brakes. Alternatively, band brakes and linear actuators for
applying forces to the band brakes may be used in
combination for applying the braking torques to the shafts.
Thus, a detailed mechanism for generating the braking
torques is not particularly limited.
The correcting-torque command unit 60 includes a torque
command generator 61 and a drive circuit 72. The torque
command generator 61 receives the bias value TS2 and the
desired take-up tension TS1 from the setting unit 80, the
tension signal T from the tension sensor 28, and the
operation preparation signal S1 from the sequence control
device 84. When the torque command generator 61 receives
the operation preparation signal S1, it calculates a
correction value for maintaining the warp tension T, that is,
the detected take-up tension, at the desired take-up tension
TS1, and outputs a torque command signal Tq representing a
torque command value Tq to the drive circuit 72, the torque
command value Tq being obtained by adding the correction
value to the bias value TS2.
A feeding-tension-applying unit referred to herein
corresponds to the feeding-torque command unit 55, the
powder brake 40, the load cell 49, and the gear transmission
mechanism for transmitting the braking force to the
corresponding sectional beam. In addition, a torque-applying
unit for applying a rotational torque to the take-up
roller corresponds to the correcting-torque command unit
60 and the auxiliary motor 24.
Fig. 4 is a block diagram showing the inner structure
of the torque command generator 61. The torque command
generator 61 mainly includes a corrector unit 62 and an
adder 68, and the corrector unit 62 includes a comparator 64,
a correction signal generator 65, a determiner 70, and an
integrator 66. In addition, a clock-signal generator 67 is
connected to the corrector unit 62. The clock-signal
generator 67 switches a clock signal CK output therefrom
between on and off at a predetermined control frequency
while the drive signal S2, which will be described below, is
being input, and supplies the clock signal CK to the
correction signal generator 65 and the integrator 66.
The comparator 64 receives the desired take-up tension
signal TS1 and the warp tension signal T, and is connected to
a setter 69a which sets thresholds of an allowable range for
the desired take-up tension TS1. The comparator 64 compares
the warp tension T with the allowable range for the desired
take-up tension TS1 and outputs a determination signal S3
representing the result of comparison to the correction
signal generator 65. The correction signal generator 65 is
connected to a setter 69b which sets an amount of correction
output when the determination signal S3 is input, and
receives a determination signal S4, which will be described
below, from the determiner 70. When the clock signal CK is
switched on, the correction signal generator 65 generates an
electrical signal corresponding to the amount of correction
set in the setter 69b in the direction to eliminate the
tension difference by referring to the determination signals
S3 and S4, and supplies the electrical signal to the
integrator 66.
When a production lot is completed or when the take-up
beam is replaced, a clear signal CLR is input to the
integrator 66 and the integrator 66 clears (initializes) an
integrated value. Otherwise, the integrator 66 maintains
the current integrated value. In addition, when the clock
signal CK is switched on, the integrator 66 integrates the
correction signal SC1 input thereto and outputs a signal SC3
representing the result of integration to one of two input
terminals of the adder 68. In addition, the bias value TS2
is input to the other one of the input terminals of the
adder 68 from the setting unit 80. When the drive signal S2
is not input, the adder 68 outputs the bias value TS2 as the
torque command signal Tq. When the drive signal S2 is input,
the adder 68 outputs the sum of two inputs, that is, the
bias value TS2 and the signal SC3, to the drive circuit 72 as
the torque command signal Tq. The bias value TS2 is also
input to the determiner 70, and the determiner 70 determines
whether the bias value TS2 is positive or negative and
outputs the signal S4 representing the result of the
determination to the correction signal generator 65.
As shown in Fig. 3, the control device 50 is connected
to the sequence control device 84 which controls the overall
operation of the warp-beaming machine 10. The sequence
control device 84 is connected to various operating buttons,
such as a start button 85a, a stop button 85b, an inching
button, and a low-speed button, sensors for detecting
abnormal yarn states, such as a yarn breakage sensor and a
fluff detection sensor, sensors for detecting abnormal
operation of the take-up device, etc. When a command signal
is input from the operating buttons, the sequence control
device 84 outputs a command signal (not shown) to perform a
required operation of the take-up device 11, such as inching
and reverse rotation. In addition, when an abnormal-state
signal is input from the above-mentioned sensors, the
sequence control device 84 turns off the operation
preparation signal S1 and the drive signal S2 to stop the
take-up device 11.
When the operator operates the start button 85a, the
sequence control device 84 turns on the operation
preparation signal S1 so that the feeding-torque command
unit 55 and the correcting-torque command unit 60 are
activated. Accordingly, the sectional beams 19a1 to 19an
receive the braking torques corresponding to the feeding
tensions 80c1 to 80cn, respectively, and the take-up roller
23 receives the force corresponding to the bias value TS2.
Then, the sequence control device 84 turns on the drive
signal S2 so that the take-up control unit 51 starts
rotating the take-up beam 29. Accordingly, the sheet of
warp yarns 31 is wound around the take-up beam 29 while
moving at a speed which is set to the low speed SL1 at first,
increased until it reaches the high speed SH1, and then
maintained at the high speed SH1. When the warp yarns 31
start moving, they are unwound from the respective sectional
beams 19a1 to 19an and the sectional beams 19a1 to 19an start
rotating. Since the braking torques applied by the powder
brakes 33a1 to 33an impede the rotations of the sectional
beams 19a1 to 19an, respectively, the warp yarns 31 receive
the feeding tension signals TSO1 to TSOn (feeding tensions
81c1 to 81cn) while they move.
In addition, the take-up roller 23 receives the
rotating torque corresponding to the bias value TS2 from the
auxiliary motor 24, and is driven and rotated along with the
warp yarns 31 while applying the torque to the warp yarns 31.
Therefore, the warp yarns 31 which are in contact with the
take-up roller 23 receive the force, that is, the tension,
corresponding to the bias value TS2 via the take-up roller 23.
The warp tension in a region downstream of the take-up
roller is balanced with that in a region upstream of the
take-up roller, and is therefore determined as the tension
applied in the region upstream of the take-up roller, that
is, the sum of the tension generated by the take-up roller
and the total feeding tension applied by the sectional beams.
In addition, it is clear from Equation (1), which determines
the above-described bias value TS2, that the warp tension in
the region downstream of the take-up roller is equal to the
desired take-up tension TS1. Thus, the warp sheet is wound
around the take-up beam at the warp tension corresponding to
the desired take-up tension TS1 immediately after the start
of the beaming operation.
After the start of the beaming operation, if the warp
tension (take-up tension) deviates from the desired take-up
tension TS1 for some reason while the warp yarns 31 are
moving, the corrector unit 62 outputs the correction value
SC3 for the initial bias value TS2. Accordingly, a tension
control operation is performed in which the torque command
value Tq input to the auxiliary motor 24 is changed such
that the warp tension approaches the desired take-up tension
with time.
More specifically, with reference to Fig. 4, when the
drive signal S2 is input, the clock-signal generator 67
outputs the clock signal CK to the correction signal
generator 65 and the integrator 66 in the form of pulses
with a predetermined control frequency. The comparator 64
continuously compares the warp tension with the allowable
range determined by the desired take-up tension TS1 and the
thresholds set by the setter 69a. When the warp tension T
deviates out of the threshold range (limit threshold range),
the comparator 64 outputs the determination signal S3
corresponding to the direction of deviation. Accordingly,
each time the correction signal generator 65 receives the
clock signal CK, it outputs the correction signal SC1
corresponding to the amount of correction, which is set in
the setter 69b, in accordance with the determination signal
S4.
The bias value TS2 may be set not only to a positive
value but also to a negative value depending on the
relationship between the desired take-up tension TS1 and the
sum of the feeding tensions 80c1 to 80cn (or the sum of the
corrected feeding tensions 81c1 to 81cn obtained using the
roll diameters di to dn). In other words, a force may be
applied to the take-up roller 23 not only in the direction
opposite to the moving direction of the warp yarns 31 but
also in the moving direction of the warp yarns 31.
Therefore, the amount of correction used in the tension
control operation must be changed depending on whether the
bias value TS2 is positive or negative. Accordingly, the
determiner 70 determines whether the bias value TS2 is
positive or negative and outputs the determination signal S4.
The correction signal generator 65 converts the amount of
correction in accordance with the determination signals S3
and S4 so that the tension difference can be eliminated, and
outputs the converted amount of correction to the integrator
66 as the correction signal SC1. The integrator 66
integrates the amount of correction input thereto each time
the clock signal CK is input. The result of integration is
input to the adder 68, and thus the torque command value Tq
is corrected.
As an example, a case is considered in which the
desired take-up tension TS1 is larger than the sum of the
feeding tensions applied by the sectional beams, that is, a
case in which the bias value TS2 is positive. When the warp
tension T is reduced below the lower limit of the threshold
range for the take-up tension, the correction signal
generator 65 outputs a correction signal SC1 representing a
positive value. Accordingly, the integrated value set in
the integrator 66 increases and the torque command value Tq
increases from the initial bias value TS2 with time. In
contrast, when the warp tension T is increased above the
upper limit of the threshold range of the take-up tension,
the correction signal generator 65 outputs a correction
signal SC1 representing a negative value. Accordingly, the
integrated value set in the integrator 66 decreases and the
torque command value Tq decreases from the initial bias
value TS2 with time. Thus, the warp-tension control
operation is performed in which the amount of correction SC3
for the bias value TS2 is changed such that the actual total
warp tension T, that is, the take-up tension approaches the
desired take-up tension TS1. Due to this tension control
operation, even when the take-up tension suddenly changes,
it returns to the desired take-up tension in order to
maintain the desired take-up tension.
In the above-described warp-beaming machine 10, when a
new lot production is started, the feeding tensions of the
sectional beams are set in accordance with the kinds of
yarns and the desired take-up tension TS1 is determined. The
desired take-up tension TS1 may either be higher or lower
than the sum of the feeding tensions of the sectional beams
since the bias value TS2 may either be positive or negative
as a result of subtraction of the sum of the feeding
tensions from the desired take-up tension TS1. When the bias
value TS2 is positive, the auxiliary motor 24 generates a
torque in the direction opposite to the moving direction of
the warp sheet (in the clockwise direction in Fig. 1) so as
to increase the take-up tension. When the bias value TS2 is
negative, the auxiliary motor 24 generates a torque in the
moving direction of the warp sheet (in the counterclockwise
direction in Fig. 1).
In the above-described warp-beaming machine 10, the
roll diameters of the sectional beams 19a1 to 19an gradually
decrease as the beaming operation proceeds, and therefore
the actual feeding tensions may become greater or smaller
than the predetermined feeding tensions. However, the roll-diameter
correctors 81a1 to 81an output the corrected feeding
tensions 81c1 to 81cn which are determined in accordance with
the reductions in the roll-diameters d1 to dn such that the
initial feeding tensions are maintained. The calculator 82
repeats the subtraction of the sum of the feeding tensions
81c1 to 81cn from the desire take-up tension TS1 and
continuously outputs the bias value TS2 which corresponds to
the corrected feeding tensions 81c1 to 81cn reflecting the
reductions in the roll-diameters. Thus, in addition to the
above-described tension control operation, the feeding
tensions 81c1 to 81cn and the bias value TS2 are also
corrected to compensate for the reductions in the roll
diameters d1 to dn of the sectional beams. Instead of
installing the circuits for compensating for the reductions
in the roll diameters of the sectional beams in the setting
unit 80, the circuits may also be provided downstream of the
setting unit 80.
The above-described embodiment may also be modified as
described below. According to the embodiment illustrated in
the figures, the determiner 70 is provided so that the
amount of correction SC3 for the bias value TS2 is added to
cause the take-up tension to approach the desired take-up
tension TS1 irrespective of whether the bias value TS2 is
positive or negative. However, the determiner 70 may also
be omitted if the bias value TS2 is determined to be either
positive or negative. In such a case, the correction signal
generator 65 outputs the correction signal SC3 based on only
the determination signal S3.
In the above-described warp-beaming machine 10, the
correcting-torque command unit 60 included in the tension
control device determines the bias value TS2 before the
operation starts, and then corrects the bias value TS2 on the
basis of the detected total warp tension T (that is, the
detected take-up tension), thereby correcting the force
applied by the auxiliary motor 24. However, the detailed
inner structure of the corrector unit 62 is not limited to
that illustrated in Fig. 4. For example, in the structure
shown in the figure, the correction signal generator 65
outputs the predetermined amount of correction when the
detected take-up tension is outside the range defined by the
thresholds. However, the correction signal SC1 may also be
output in accordance with the difference between the
detected take-up tension and the desired take-up tension TS1.
In addition, with reference to Fig. 4, the integrator 66
(that is, an integral element) is used for temporally
varying the correction value in response to the variation in
the tension applied to the warp sheet. However, a
proportional element or a differential element may also be
added to increase the response speed. In addition, a PID
control device including all of them may also be used.
In the above-described embodiment, a closed-loop
tension control system is constructed such that the force
(torque) applied to the take-up roller is corrected on the
basis of the take-up tension detected by the tension sensor
28 so that the desired take-up tension TS1 is maintained
after the operation starts. However, the structure may also
be simplified by omitting the tension control system and
applying a force corresponding to the bias value TS2, which
is determined by subtracting the sum of the feeding tensions
81c1 to 81cn of the sectional beams from the desired take-up
tension TS1, to the take-up roller 23.
While the warp-beaming machine 10 is being operated,
some of the torque generated by the auxiliary motor 24 in
accordance with the bias value TS2 for the take-up operation
is used for driving the take-up roller and the like.
Accordingly, the actual force applied to the warp sheet by
the take-up roller is probably smaller than the bias value
TS2. Therefore, the bias value TS2 is preferably corrected
to compensate for a mechanical torque loss (mechanical loss)
caused by driving the take-up roller or the like. The
mechanical loss is considered to increase as the rotational
speed increases, and the bias value TS2 is more preferably
corrected to compensate for the mechanical loss in
accordance with the moving speed of the warp sheet. More
specifically, the adder 68 may be connected to a mechanical-loss
compensator (not shown) which outputs a mechanical-loss-compensating
value corresponding to the rotational
speed of the take-up roller, that is, the moving speed of
the warp sheet. In such a case, the adder 68 adds the
mechanical-loss-compensating value to the above-described
calculation result and outputs the result as the torque
command value Tq. However, the mechanical loss compensator
may also be omitted.
In the above-described embodiment, the auxiliary motor
24 is not particularly limited as long as it is an actuator
which generates a torque in accordance with a supplied
current. For example, the auxiliary motor 24 may be a
direct current motor or a torque motor. In addition, the
torque of the motor may also be controlled using a current
generator in combination, and the method for generating the
torque is not limited. In addition, the roll diameters of
the sectional beams and the take-up beam may also be
estimated on the basis of the relationship between the
amount of rotation of each beam and the amount of movement
of the warp yarns instead of using the roll diameter sensors
34 and 39 (39a1 to 19an).
In addition, although the speed signal generator 52,
the torque signal generators 57a1 to 57an, and the torque
command generator 61 included in the control device 50 are
composed of independent circuits, they may also be
constructed as a single circuit. For example, the
sequential processes and control operations, the calculation
of the bias value, etc., may of course be performed using a
microcomputer and a software program.