BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a technique for preventing light filling bars caused
by an insufficient beating force at the start of operation of a loom by executing
a so-called blank beating start. In the blank beating start, a reverse rotation and
operation without weft insertion are performed before starting weft insertion. More
particularly, the present invention relates to a technique for preventing fabric defects
caused when the blank beating start is executed irrespective of the characteristics
of the weft.
2. Description of the Related Art
[0002] If a loom stops during a weaving operation, weft bars are easily generated when restarting
the operation of the loom. In a normal start in which weft insertion is started after
a drive operation signal is generated, the loom is activated, and beat-up motion is
performed, weft bars are generated because the beating force immediately after the
activation is weaker than that during steady operation. In comparison, a loom activation
method called a blank beating start is disclosed in Japanese Unexamined Patent Application
Publication No. 61-124651. In this method, when a loom is activated, a motor in the
loom is rotated in the reverse direction by a predetermined amount, and then the main
shaft of the loom is activated in the forward direction and is rotated in the forward
direction by the same amount as the previous reverse rotation while performing blank
beating, which is beat-up motion without weft insertion. Then, weft insertion is started.
In looms, the above-mentioned starting methods are selectively used depending on the
conditions of the weft bars.
[0003] When the reverse operation is performed upon reactivation of the loom as described
above, a selvedge device which supplies selvedge yarns for restraining weft at the
side edges of woven fabric to form selvedges also operates in the reverse direction.
Therefore, a weft yarn positioned at a cloth fell upon reactivation receives no restraining
force from the selvedge yarns or warp. Accordingly, in looms using the above-described
activation method involving the blank beating start, if yarns like textured yarns
and twisted yarns having contractile force (elasticity force) are used as the weft,
the weft yarn positioned at the cloth fell will contract since it receives no restraining
force from the selvedge yarns or the warp and accordingly fabric defects will occur.
SUMMARY OF THE INVENTION
[0004] Therefore, an object of the present invention is to control the activation of a loom
which selectively executes one of a plurality of starting methods at the start of
the operation of the loom, the starting methods including a blank beating start involving
a reverse operation and a normal start. The loom is activated with a starting method
which does not involve the reverse operation depending on the characteristics of the
weft, more specifically, when the weft has elasticity.
[0005] According to a first aspect of the present invention, a start control apparatus of
a loom includes a control unit which selects one of a plurality of starting methods
and operates the loom in accordance with the selected starting method when a drive
operation signal is input; and a weft-insertion control unit which selectively inserts
one of a plurality of kinds of weft in accordance with information regarding weft
selection while the loom is in operation. The starting methods include a normal start
and a blank beating start in which a loom main shaft is rotated in a reverse direction
by a predetermined amount, beat-up motion is performed without weft insertion while
activating the loom, and then weft insertion is started, the amount of reverse rotation
in the blank beating start being set such that a weft yarn positioned at a cloth fell
is released from warp yarns. In addition, according to the present invention, when
the drive operation signal is generated, whether or not the weft yarn positioned at
the cloth fell has elasticity is determined on the basis of the information regarding
weft selection, and the normal start is executed if it is determined that the weft
yarn has elasticity. The information regarding weft selection includes not only weft
selection information but also a weft-insertion pick number (count value) on the basis
of which a weft selection signal is generated.
[0006] The information regarding the elasticity of the weft includes not only information
which directly shows the elasticity, such as a twist direction, the number of twists
per unit length, and whether or not an elasticizing process has been performed, but
also information which indirectly reflects the above-mentioned information, such as
a part number of a weft supplier. In addition, the information regarding the elasticity
of the weft also includes information showing the degree of elasticity in addition
to the presence/absence thereof. An evaluation criterion for the elasticity may be
adequately set depending on the kind of the weft such that fabric defects can be prevented.
In addition, the information regarding the elasticity may be manually input by the
operator, read out from a memory medium such as a memory card, or automatically set
via a loom management computer connected to the loom.
[0007] According to the first aspect, in looms of a multicolor weft insertion type in which
multiple kinds of weft are selectively inserted in accordance with the weft selection
information corresponding to the weft-insertion pick number, when a drive operation
signal is generated, whether or not a weft yarn positioned at the cloth fell has elasticity
can be determined on the basis of the information regarding weft selection such as
the weft selection signal and the weft-insertion pick number. Accordingly, when the
drive operation signal of the loom is generated, if the weft yarn has elasticity according
to the result of the above-described determination, the normal start which does not
involve the reverse rotation is executed instead of the blank beating start which
involves the reverse rotation. In reverse, if the weft yarn has no elasticity, either
one of the blank beating start which involves the reverse rotation or the normal start
may be executed. Accordingly, fabric defects caused when the blank beating start is
executed and the loom main shaft is rotated in the reverse rotation at the start of
operation since the weft yarn having elasticity contracts by being released from the
warp are prevented.
[0008] In the first aspect, the normal start executed instead of the blank beating start
may be performed manually. More specifically, the operator may visually check the
result of determination and operate the loom by pressing an operation button selected
from among a plurality of operation buttons provided in correspondence with the starting
methods. Alternatively, it may also be automatically determined whether or not the
blank beating start is adequate when the operator presses the operation button, and
the loom may be operated with a starting method corresponding to the result of determination.
As an example for realizing the latter system, when a drive operation signal is input,
the control unit determines whether or not the weft yarn positioned at the cloth fell
has elasticity on the basis of the information regarding weft selection, and executes
the normal start when the weft yarn is determined to have elasticity. If the weft
yarn is determined to have no elasticity, either one of the blank beating start or
the normal start may be selected as the starting method, and the starting method is
adequately set depending on the specifics of the fabric.
[0009] According to a second aspect of the present invention, a start control apparatus
of a loom includes a setting unit to which selection information for selecting one
of a plurality of starting methods and information regarding elasticity of weft are
input; and a control unit which operates the loom in accordance with the selected
starting method when a drive operation signal is input. The starting methods include
a normal start and a blank beating start in which a loom main shaft is rotated in
a reverse direction by a predetermined amount, beat-up motion is performed without
weft insertion while activating the loom, and then weft insertion is started, the
amount of reverse rotation in the blank beating start being set such that a weft yarn
positioned at a cloth fell is released from warp yarns. In addition, according to
the present invention, one of the setting unit and the control unit determines whether
or not to restrict the selection of the blank beating start on the basis of the input
information regarding the elasticity of the weft. According to the second aspect,
whether or not the selection of the blank beating start is to be restricted is automatically
determined on the basis of the information regarding the elasticity of the weft input
to the setting unit. Therefore, when the weft having elasticity is used, the normal
start, which is the substitute starting method for the blank beating start, may be
executed in accordance with the result of determination. Accordingly, similar to the
first aspect, unlike the known system, fabric defects caused by the contraction of
the weft yarn when the blank beating start is performed (that is, when the reverse
rotation of the loom main shaft is performed) are prevented.
[0010] The information regarding the result of determination obtained in the first and second
aspects may be displayed in a visible manner via the setting unit. For example, with
regard to the first aspect, the fact that the weft yarn positioned at the cloth fell
has elasticity or the fact that the selection of the blank beating start is inadequate
are displayed. Accordingly, the operator recognizes that the starting method is inadequate
and corrects the setting of the starting method or manually operates the loom with
the starting method other than the blank beating start. Thus, the fabric quality can
be adequately controlled by checking the information showing the result of determination.
[0011] The normal starting method may include, for example, at least one of (1) a first
start in which the loom is activated at a current drive operation position, beat-up
motion is performed, and then weft insertion is started and (2) a second start in
which the loom is activated at the current drive operation position, weft insertion
is started, and then the beat-up motion is performed. More specifically, the normal
starting method may include one or both of (1) and (2). When both of (1) and (2) are
included, one of them may be set in advance or be selected in accordance with a predetermined
algorithm on the basis of weaving conditions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012]
Fig. 1 is a diagram showing the overall structure of an air jet loom to which the
present invention is applied;
Fig. 2 is a block diagram showing the internal structure of a control apparatus included
in the loom according to the present invention;
Fig. 3 is a diagram showing an operational flow performed between the period from
the occurrence of a cause of stoppage to the start of the loom's operation in a case
in which a 300° start is selected as a normal start in a start control of the loom
according to the present invention in which whether or not to restrict the selection
of a blank beating start is determined;
Fig. 4 is a diagram showing an example of setting of weft selection information on
the basis of which it is determined whether or not the selection of the blank beating
start is to be restricted in the present invention;
Fig. 5 is a flowchart showing a process in which a control unit determines whether
or not to restrict the selection of the blank beating start in the start control of
the loom according to the present invention;
Fig. 6 is a flowchart showing a process in which a setting unit determines whether
or not to restrict the selection of the blank beating start in a setting phase according
to the present invention; and
Fig. 7 is a diagram showing an operational flow performed between the period from
the occurrence of a cause of stoppage to the start of the loom's operation in a case
in which a 60° start is selected as the normal start in the start control of the loom
according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0013] Embodiments of the present invention will be described below with reference to the
accompanying drawings. Fig. 1 shows an air jet loom 10 of a two-color weft insertion
type which selectively inserts two kinds of weft depending on a weft-insertion pick
number.
[0014] The loom 10 includes weft suppliers 12a and 12b for supplying weft yarns 11a and
11b, respectively, weft feeders 13a and 13b, stopper pins 14a and 14b installed adjacent
to the weft feeders 13a and 13b, main nozzles 15a and 15b for inserting the weft yarns
11a and 11b by air jet, and a plurality of sub nozzles 16, 16... disposed in a warp
shed 21 along a weft-insertion path for pushing the weft yarn 11a or 11b being inserted
by the air jet. The main nozzles 15a and 15b are connected to their respective electromagnetic
valves 17 and 17 and pressure adjusters 18 and 18 constituted of, for example, electro-pneumatic
proportional valves or the like via air tanks (not shown). The sub nozzles 16, 16...
disposed along the weft-insertion path are classified into a plurality of groups along
the weft insertion direction, and each group is connected to an electromagnetic valve
17 and a pressure adjuster 18 via an air tank (not shown). The pressure adjusters
18, 18... are connected to a common fluid source 19 for supplying compressed air.
Various devices of the loom 10 including a warp shedding device (not shown), a reed
22, a weft cutter 26, etc., are linked to a main shaft 20 of the loom 10 via motion
conversion mechanisms (not shown), and a weft feeler 25 for detecting the weft yarn
is disposed so as to face the weft-insertion path at a position near a fabric edge
opposite from a weft-insertion position.
[0015] The weft feeders 13a and 13b retain the weft yarns 11a and 11b, respectively, by
rotating yarn guides and winding the weft yarns 11a and 11b around drums, and the
weft yarns 11a and 11b are restrained by the stopper pins 14a and 14b, respectively,
which move toward and away from the circumferential surfaces of the drums. When the
weft yarn 11a is selected, a weft-insertion control unit 28, which will be described
below, operates such that the stopper pin 14a corresponding to the selected weft yarn
11a is retracted so as to release the weft yarn 11a wound around the drum in the open
phase of the warp shed. At the same time, the electromagnetic valves 17, 17... are
opened and closed such that the weft-insertion nozzles including the main nozzle 15a
corresponding to the selected weft yarn 11a and the sub nozzles 16, 16... blow compressed
air in relays. Accordingly, the selected weft yarn 11a is released from the weft feeder
13a and is inserted as shown in the figure. Then, when the weft yarn 11a is released
from the weft feeder 13a by a predetermined number of windings, the weft-insertion
control unit 28 causes the stopper pin 14a to extend and stop the weft yarn 11a. The
inserted weft yarn 11a is beaten by the reed 22, cut by the weft cutter 26, and thereby
becomes a part of a woven fabric 23. In this manner, the weft yarns 11a and 11b are
selectively inserted and are woven into the fabric. The above-described air jet loom
10 is of the two-color weft insertion type in which the weft yarns 11a and 11b are
selectively inserted in each rotation of the loom in accordance with a weft-insertion
pattern. However, the loom may also be of a single-color weft insertion type, a three-color
weft insertion type, or more.
[0016] The electromagnetic valves 17, 17... , the weft feeders 13a and 13b, and the stopper
pins 14a and 14b are connected to output terminals of the weft-insertion control unit
28. An angle detector 27 constituted of, for example, a rotary encoder is connected
to the loom main shaft 20, and an electric signal representing a crank angle of the
main shaft 20 is output by the angle detector 27. An angle signal θ is input to an
input terminal of the weft-insertion control unit 28, and a setting unit 50 for setting
information such as conditions of weft insertion is connected to the weft-insertion
control unit 28.
[0017] Fig. 2 is an internal block diagram of a control apparatus 30 of the loom which functions
as a start control apparatus of the loom according to the present invention. The control
apparatus 30 of the loom basically includes a control unit 32 to which the angle signal
θ is input, the weft-insertion control unit 28 which controls actuators of the above-described
weft-insertion devices, and the setting unit 50 for transmitting set values to the
control units 32 and 28. The control unit 32 includes a main controller 34 which controls
the overall operation of the loom and a determination unit 40 which outputs a weft
selection signal S1 and determines whether or not to restrict the selection of the
blank beating start.
[0018] The determination unit 40 basically includes a stepping-signal generator 41 which
generates a forward-rotation stepping signal Sf or a reverse-rotation stepping signal
Sr each time the loom main shaft angle θ reaches a predetermined angle depending on
the rotational direction of the main shaft and a signal generator 42 which counts
the stepping signals Sf and Sr input thereto and outputs a signal representing the
count value as a weft pick number. The angle signal θ is input to the stepping-signal
generator 41. Each time the loom operates by one turn and the input angle reaches
the predetermined angle (for example 0°), the stepping-signal generator 41 generates
a single pulse of either the forward-rotation stepping signal Sf or the reverse-rotation
stepping signal Sr depending on the rotational direction. The signal generator 42,
which will be described in detail below, memorizes a weft selection pattern set via
the setting unit 50, and is capable of counting the number of pulses of the two stepping
signals Sf and Sr input to the signal generator 42. Accordingly, each time the input
angle reaches the predetermined angle and the forward-rotation stepping signal Sf
or the reverse-rotation stepping signal Sr is input, the signal generator 42 increments
or decrements a weft-insertion pick count value by 1 and outputs the weft selection
signal S1 corresponding to the pick count value on the basis of the memorized weft
selection pattern. The determination unit 40 functions not only as a weft-selection-signal
generator but also as a determination circuit which generates a blank-beating-start
restriction signal S3. This will be described in more detail below. In the pick count
performed by the signal generator 42, if the stepping signal Sf is input while the
pick count value is at an upper limit "5", the signal generator 42 returns the pick
count value to "1". In reverse, if the stepping signal Sr is input while the pick
count value is at a lower limit "1", the signal generator 42 returns the pick count
value to "5".
[0019] The main controller 34 includes, for example, a microprocessor unit (MPU), a memory
which stores software, such as a control program of the loom, and a port for inputting/outputting
signals to the MPU, none of which is shown in the figure. The main controller 34 receives
signals from the loom's operation buttons including an drive button 35a, a reverse
rotation button 35b, and a stop button (not shown); the main shaft angle signal θ
from the angle detector 27; and abnormal signals from the weft feeler 25, a warp breakage
sensor (not shown), etc. In addition, the main controller 34 outputs, for example,
an activation signal S6, a reverse-rotation signal S7, and a brake command signal
S8 to current generators 36 and 37 which supply current to a motor 38 and a loom brake
39, respectively, via ports (not shown), and also outputs an drive signal S4, a blank-weaving
command signal S5, an activation preparation signal S9, etc., to the weft-insertion
control unit 28, a warp control unit 44, which will be described below, and a weft
detection unit 45 to which the weft feeler 25 is connected.
[0020] The setting unit 50 includes, for example, a touch-panel setting display 51 having
a display function and is connected to the weft-insertion control unit 28, the main
controller 34, and the determination unit 40 so that necessary information can be
set and communicated between these units and the setting unit 50. More specifically,
with regard to the determination unit 40, the setting unit 50 sets weft selection
information for each weft-insertion pick number and information regarding elasticity
of the weft. In addition, with regard to the weft-insertion control unit 28, the setting
unit 50 sets data regarding weft insertion for each kind of selectable weft, the data
including timing at which the compressed air is to be discharged from the main nozzle
and sub nozzles, pressures of the compressed air supplied to the nozzles, the amount
of rotation of a flyer of the weft feeder, that is, the number of windings of the
weft yarn for each pick of weft insertion, and timing at which the weft yarn is to
be released from the stopper pin. Further, the setting unit 50 sets data regarding
the selectively set starting method and conditions for the set starting method in
the main controller 34, and data regarding warp tension control and weft density control
such as warp tension, a warp-beam diameter, and a weft density in the warp control
unit 44. Such information may be input manually by the operator, read out from a memory
medium such as a memory card, or automatically set via a loom management computer
connected to the loom.
[0021] During steady operation, the activation signal S6 is output from the main controller
34, and accordingly the current generator 36 supplies current to the motor 38. The
motor 38 rotates the main shaft 20 of the loom, and the angle signal θ corresponding
to the rotation of the main shaft 20 is input to the stepping-signal generator 41,
the weft-insertion control unit 28, and the main controller 34. Each time the main
shaft 20 is rotated by one turn and the angle signal θ reaches 0°, the stepping-signal
generator 41 outputs the stepping signal Sf and the signal generator 42 increments
the count value of the weft-insertion pick number by 1. Then, on the basis of the
memorized weft selection pattern and the incremented pick number, the signal generator
42 outputs one of selection signals CL1 and CL2 corresponding to the weft-insertion
devices to the weft-insertion control unit 28 as the weft selection signal S1. Then,
in order to insert the weft yarn corresponding to the weft selection signal S1, the
weft-insertion control unit 28 outputs drive signals to the electromagnetic valves
17 and the pressure adjusters 18 under conditions set for each kind of weft (jet start
angles, jet finish angles, and pressures), and drives the corresponding stopper pin
14 and the weft feeder 13 at the same time. The warp control unit 44 is a known device
which detects a warp tension at a predetermined angle and rotates a warp beam (not
shown) so as to maintain a desired warp tension during the operation of the loom.
The warp control unit 44 also rotates a take-up roller (not shown) for winding the
woven fabric such that the rotational speed of the loom and the weft density are maintained
at predetermined values.
[0022] A process performed between the period from the occurrence of a cause of stoppage
of the loom 10 during steady operation to the start of the loom's operation will be
described in detail below with reference to Fig. 3.
[0023] In the loom 10, it is assumed that a total step number of the weft selection information
is "5". More specifically, it is assumed that the weft selection pattern corresponding
to the weft selection information is set such that a process of inserting a weft yarn
"a" having no elasticity for four picks and a weft yarn "b" having elasticity for
one pick is repeated. The setting unit 50 sets, in the form of symbols, the selection
information regarding the weft-insertion device (the main nozzle and the weft feeder)
to which the weft is set for each weft-insertion pick number in the signal generator
42 included in the determination unit 40. The weft selection information (weft selection
pattern) is transmitted to the signal generator 42 and is memorized in the form shown
in, for example, Fig. 4. The loom 10 is operated under the above-described conditions.
[0024] During steady operation, if, for example, a weft-insertion error occurs as a cause
of stoppage and a weft-insertion stop signal is generated when the weft-insertion
pick number is "1", that is, when the weft yarn "a" is being inserted, the main controller
34 turns off the drive signal S4 and stops the motor 38 via the current generator
36. In addition, the main controller 34 outputs the brake command signal S8 and activates
the brake 39 via the current generator 37 to immediately stop the rotation of the
loom main shaft 20. Then, the main controller 34 rotates the main shaft 20 in the
reverse direction until it reaches a predetermined angle (300°), so that the warp
shed is closed in the standby state. When the operator arrives, he or she operates
the reverse rotation button 35b to rotate the main shaft 20 in the reverse direction
until it reaches 180°, and removes the defective weft yarn "a" appearing at the cloth
fell 24. Then, the operator presses the reverse rotation button 35b again, and rotates
the main shaft 20 in the reverse direction until it reaches a predetermined angle
(300°), which is a drive operation position. Then, the operator presses the drive
button 35a to restart the loom 10.
[0025] The setting unit 50 communicates with the operator through a display screen (not
shown) on the setting display 51 so as to set weaving conditions of the loom, and
a plurality of starting methods including the blank beating start and a normal start,
which will be described below, are set such that they can be selected. In the setting
unit 50, information showing that the blank beating start is to be selected as a preferred
starting method and a 300° start is to be selected as a substitute starting method
if the blank beating start is determined to be inadequate is set by the operator before
starting the weaving operation.
[0026] In the present embodiment, detailed settings regarding the blank beating start set
as the preferred starting method are determined as below as an example. First, the
main shaft is rotated in the reverse direction from the main shaft angle 300°, which
is the current drive operation position, by about one and a half turns and is stopped
at 120°. Then, the loom is activated (forward direction) and blank weaving without
weft insertion is performed for one and a half turns. Then, weft insertion is started.
In the present embodiment, even though the blank beating start is set as the preferred
starting method by the setting unit 50, if the weft yarn positioned at the cloth fell
when the drive operation signal is input is determined to have elasticity, the operation
of the loom is started by executing the 300° start, which is the normal start, as
the substitute starting method for the blank beating start. If the weft yarn is determined
to have no elasticity, the operation of the loom is started by executing the blank
beating start, which is set as the preferred starting method.
[0027] When the operator presses the drive button 35a, the main controller 34 outputs a
determination command signal S2 to the determination unit 40, and the determination
unit 40 performs a predetermined determination in response to the input signal and
outputs the blank-beating-start restriction signal S3 depending on the result of determination.
After a predetermined time period from the output of the determination command signal
S2, the main controller 34 selectively executes one of the starting methods depending
on the blank-beating-start restriction signal S3 and starts the operation of the loom
10.
[0028] Fig. 5 shows the flow of a process performed by the main controller 34 in a period
from the input of the drive operation signal S0 to the main controller 34 to the start
of operation of the loom. First, when the drive button 35a is pressed and the drive
operation signal S0 is input to the main controller 34, the main controller 34 outputs
the determination command signal S2 to the determination unit 40 (Step 1) and reads
out the starting method and detailed conditions regarding the starting method set
in the setting unit 50 in advance (Step 2). The conditions include the amount of reverse
rotation for the blank beating start (the number of picks of the reverse rotation
and the main shaft crank angle at which the reverse rotation is to be stopped), and
these conditions are set in the setting unit 50 in advance. Then, the main controller
34 checks whether or not the starting method set as the preferred starting method
is the blank beating start (Step 3). If the blank beating start is set as the starting
method (that is, if the result is 'yes'), the main controller 34 checks whether or
not the blank-beating-start restriction signal S3 is output from the determination
unit 40 (Step 4).
[0029] If the output of the blank-beating-start restriction signal S3 from the determination
unit 40 is off in Step 4 (that is, if the result is 'no'), the process proceeds to
the next step, i.e. Step 5 and the blank beating start set as the preferred starting
method is executed. Then, the starting method-selecting process is finished. In addition,
if it is determined that a starting method other than the blank beating start is set
in Step 3 or if the output of the blank-beating-start restriction signal S3 from the
determination unit 40 is on in Step 4 (that is, if the result is 'yes'), the process
proceeds to Step 6 and the normal start (the 300° start described below), which is
the starting method set as the substitute starting method for the blank beating start,
is executed. Then, the starting method selecting process is finished.
[0030] In addition to the function of outputting the weft selection signal, the signal generator
42 shown in Fig. 2 also has a function of determining whether or not the weft yarn
which is already woven in and positioned at the cloth fell has elasticity, in other
words, whether or not the weft yarn would contract in the reverse rotation of the
blank beating start, and outputs the blank-beating-start restriction signal S3 depending
on the result of determination. More specifically, the setting unit 50 transmits the
information regarding whether or not the weft has elasticity, which is the information
regarding the elasticity of the weft, to the signal generator 42 in correspondence
with the symbols of the weft-insertion devices (the main nozzles and the weft feeders)
to which the weft is set. Accordingly, the signal generator 42 is capable of recognizing
that the weft yarn "a" having no elasticity is set in the main nozzle 15a and the
weft feeder 13a included in the weft-insertion device corresponding to the symbol
"a", and that the weft yarn "b" having elasticity is set in the main nozzle 15b and
the weft feeder 13b included in the weft-insertion device corresponding to the symbol
"b".
[0031] When the determination command signal S2 is input from the main controller 34 in
Step 1 as described above, the signal generator 42 determines whether or not to restrict
the selection of the blank beating start in accordance with, for example, a predetermined
software algorithm, depending on the selected weft from the current weft pick number
to that at the end of the reverse rotation in the blank beating start on the basis
of the weft selection information and the amount of reverse rotation in the blank
beating start. Then, the signal generator 42 outputs the blank-beating-start restriction
signal S3 depending on the result of determination. As described above, the pick count
value (weft pick number) of the signal generator 42 is synchronized with the rotation
of the loom main shaft (the forward or reverse rotation of the loom main shaft) while
the electric power to the control apparatus 30 is turned on. The loom 10 is stopped
at the weft-insertion pick number "5" and the angle 300°. The weft selection signal
in this state corresponds to the kind of the weft yarn which is already woven in and
positioned at the cloth fell. Since the loom is stopped at the weft-insertion pick
number "5" and the weft yarn "b" having elasticity is selected, the signal generator
42 determines that the weft yarn would contract if the reverse rotation is performed
and turns on the output of the blank-beating-start restriction signal S3, as shown
in Fig. 4.
[0032] In this case, only the weft yarn "b" of the two kinds of weft yarns "a" and "b" has
elasticity. Since the output of the blank-beating-start restriction signal S3 is substantially
the same as the weft selection signal CL2, as is clear from Fig. 4, the output of
the selection signal CL2 may also be used in place of the output of the blank-beating-start
restriction signal S3. However, since a fabric may be woven using three or more kinds
of weft and there may be more than one kind of weft that has elasticity, it is not
advisable to select a substitute signal for each case. In this view, the algorithm
for determining whether or not to restrict the selection of the blank beating start
is preferably capable of adequately providing an output irrespective of the combinations
of the kinds of weft and the number of weft-insertion devices to which the weft is
set.
[0033] Accordingly, in the above-described case, the main controller 34 reads out information
indicating that the blank beating start is set as the preferred starting method in
Step 2, determines that the output of the blank-beating-start restriction signal S3
is on in Step 4, and executes the 300° start, which is the normal starting method
selected as the substitute starting method, in Step 6.
[0034] When the 300° start, which is the normal starting method, is selected, the loom is
activated at 300°, which is the current drive operation position, as shown by the
solid line in Fig. 3. More specifically, the beat-up motion is carried out once and
the operation of the loom 10 is started by inserting the weft yarn "a" corresponding
to the weft-insertion pick number "1".
[0035] For reference, the above-described blank beating start is shown by a dashed line
in Fig. 3. In the blank beating start, first, the reverse rotation is performed from
the current drive operation position 300° by about one and a half turns (to 120° where
the weft-insertion pick number is "4", which corresponds to the previous pick). Then,
the loom is activated in the forward direction while the output of the blank-weaving
command signal S5 is turned on, so that blank weaving without weft insertion is performed
for one and a half turns, in which the beat-up motion is carried out twice. Then,
the output of the blank-weaving command signal S5 is turned off and the operation
of the loom is started by restarting weft insertion with the weft yarn "a" corresponding
to the weft-insertion pick number "1". In this case, when the main shaft 20 of the
loom is rotated in the reverse direction from the current drive operation position
300° in the blank beating start and the warp shed is opened accordingly, the weft
yarn "b" having elasticity is released from the warp and the selvedge yarns and contracts.
Therefore, a fabric defect occurs. The main shaft angle at which the contraction of
the weft yarn occurs varies depending on the shedding conditions in the warp shedding
device such as dwell in the shedding curve, the area of the warp shed, and cross timing,
the conditions of the selvedge device, the characteristics of the warp and weft, etc.
As an example, in a certain loom, a main shaft angle around 260° is the limit when
the cross timing of the warp shedding device is 300°.
[0036] According to the present invention, even when the operator selects the blank beating
start as the preferred starting method through the setting unit 50 by mistake without
taking the elasticity of the weft into account, if the input information regarding
the elasticity of the weft indicates that the weft has elasticity, the normal start
is automatically selected as the substitute starting method for the blank beating
start which involves the reverse rotation when the loom is operated. Therefore, unlike
the known system, fabric defects caused when the blank beating start involving the
reverse rotation is executed irrespective of whether or not the weft has elasticity
and the weft yarn "b" having elasticity which has already been woven in contracts
by being released at the cloth fell are prevented.
[0037] In the above-described embodiment, the weft selection pattern and the detailed settings
for the selected start (settings regarding the start of the loom such as the amount
of reverse rotation in the blank beating start) are not limited to the above-described
example, and may be adequately set depending on the specifics of the fabric.
[0038] The above-described embodiment may also be modified as below. That is, the information
for determining whether of not the weft at the drive operation has elasticity is not
limited to the weft selection information (weft selection pattern). For example, weft
having high elasticity somewhat contracts in a period from the end of discharge of
the jet from the weft-insertion nozzles to the time at which the beat-up motion is
carried out. Accordingly, the contraction of the weft yarn may be directly detected
using the yarn signal from the weft feeler 25 and be memorized for each weft-insertion
pick, and this information may be used instead of the weft selection information.
The method for detecting the contraction of the weft yarn is not particularly limited.
[0039] The elasticity of the weft may also be evaluated on the basis of the degree of elasticity
(the amount of contraction per unit length) in addition to the presence/absence thereof.
When the degree of elasticity is used, the evaluation criterion may be adequately
set depending on whether the fabric defects will occur due to the contraction of the
weft yarn.
[0040] In the above-described embodiment, the blank-beating-start restriction signal is
generated on the basis of the weft selection information and the information regarding
whether or not the weft has elasticity. However, if, for example, the step number
is relatively small as in the case where the loom is of the two-color weft insertion
type and two kinds of weft are alternately inserted in, for example, two-color one-pick
(1×1) or two-color two-pick (2x2) pattern, or if the weft having elasticity is always
set in a predetermined one of the weft-insertion devices, the weft selection signal
S1 corresponding to the weft-insertion device to which the weft having elasticity
is set (one of CL1, CL2...) may also be used instead of the blank-beating-start restriction
signal S3. In addition, instead of using the weft selection signal S1, the information
which the weft selection signal is based on, for example, the ordinality of whether
the weft-insertion pick number is even number or odd number may also be used for outputting
the blank-beating-start restriction signal S3. In other words, the selection of the
blank beating start may also be restricted depending only on the weft selection information
without using the information regarding whether or not the weft has elasticity.
[0041] In addition, the blank-beating-start restriction signal S3 may also be generated
depending only on the information regarding the elasticity of the weft. More specifically,
the signal generator 42 in the determination unit 40 receives the information regarding
the elasticity of the weft from the setting unit 50, and outputs the blank-beating-start
restriction signal S3 if it determines that at least one of a plurality of kinds of
weft has elasticity. In such a case, the loom is operated by executing the normal
start, which is set as the substitute starting method, irrespective of the preferred
starting method set by the setting unit 50.
[0042] In the above-described first embodiment, the following modifications are possible.
First, although the blank beating start is set as the preferred starting method for
the case in which the weft yarn positioned at the cloth fell when the drive operation
signal is generated has no elasticity in the above-described embodiment, the setting
may also be such that the normal start is executed. The starting method for the case
in which the weft yarn has no elasticity may be selected from the blank beating start
and the normal start, which is the substitute starting method for the blank beating
start, by taking the actual states of weft bars and other conditions into account.
[0043] In the first embodiment, a single preferred starting method is set in the setting
unit 50 in advance, and the substitute starting method, which is also set in advance,
is executed instead of the preferred starting method depending on the result of determination
regarding the elasticity of the weft yarn positioned at the cloth fell. However, various
other methods are possible with regard to the selective execution of the starting
methods. For example, the starting method to be executed when the drive operation
signal is generated may also be set for each of the weft-insertion pick numbers in
advance by the setting unit 50 in accordance with the elasticity of the weft yarn
positioned at the cloth fell. When the drive operation signal is generated, the control
unit 32 checks the weft-insertion pick number, and the operation of the loom is started
using the starting method corresponding to the determined pick number. As described
above, the weft-insertion pick number is updated in synchronization with the rotation
of the main shaft in the operation of the loom and the reverse rotation. Therefore,
the use of the weft pick number when the drive operation signal is generated is included
within the scope of the first aspect of the present invention in which whether or
not the weft yarn positioned at the cloth fell when the drive operation signal is
generated has elasticity is determined on the basis of the information regarding the
weft selection.
[0044] In addition, in the above-described embodiment, determination of whether or not the
weft yarn positioned at the cloth fell has elasticity is performed when the drive
operation signal S0 is generated. However, the drive operation position of the loom
(for example, the operation corresponding to the amount of reverse rotation of the
loom main shaft in the recovery operation for the weft insertion error) is sometimes
uniquely determined depending on the cause of stoppage. Accordingly, the position
(main shaft angle) at which the drive operation is performed may be estimated from
the kind of a signal representing the cause of stoppage before the generation of the
drive operation signal (more specifically, in a period from the generation of the
signal representing the cause of stoppage to the generation of the drive operation
signal). Then, similar to the above-described embodiment, the determination is performed
based on the weft selection information. Thus, the time at which whether or not the
weft yarn has elasticity is determined is not limited. The causes of stoppage are
classified into a weft trouble, such as the weft insertion error, and other troubles,
such as the warp breakage and the operation of a stop button. This is because the
amount of rotation (amount of reverse rotation) of the loom main shaft performed for
the recovery operation differs depending on whether or not the cause of stoppage is
related to the weft trouble. More specifically, when the weft trouble occurs, reverse
rotation of more than one turn from the standby angle at the time of stoppage (300°)
is manually performed for removing the defective weft yarn, and then the loom is operated.
In comparison, when the cause of stoppage is not related to the weft trouble, the
loom is directly operated from the standby angle at the time of stoppage of the loom
(300°).
[0045] In the above-described embodiment, the normal start is automatically selected instead
of the blank beating start depending on the result of determination based on the weft
selection information or the kind of weft yarn. However, instead of the automatic
process, a warning about the risk of fabric defects due to the contraction of the
weft may also be issued. For example, a dedicated warning lamp may be turned on or
a warning message like "risk of fabric defects due to reverse rotation in blank beating
start" may be shown on the setting display 51 of the setting unit 50 to attract the
operator's attention. When the operator notices the warning, he or she operates the
drive operation button corresponding to the normal start to start the operation with
the normal start instead of the blank beating start which involves the reverse rotation,
or resets the selected starting method to the normal start.
Second Embodiment
[0046] A second embodiment of the present invention will be described below. In the first
embodiment, the normal start, which is the substitute starting method for the preferred
starting method, is executed by the control unit 32 which controls the loom. In comparison,
in the second embodiment, this is performed by the setting unit 50. More specifically,
when the operator sets weaving conditions of the loom, the information regarding the
elasticity of the weft is input first and the setting unit 50 determines whether or
not the weft has elasticity. If it is determined that the weft has elasticity, the
blank beating start which involves the reverse rotation is eliminated from the list
of settable starting methods so that only the normal start can be set. The circuit
structure corresponding to this embodiment is obtained simply by removing the blank-beating-start
restriction signal S3 from the structure shown in Fig. 2, and therefore explanations
regarding the circuit are omitted.
[0047] Fig. 6 shows the flow of a process performed by the setting unit 50 when the operator
sets the weaving conditions. First, the operator inputs weft-kind information by operating
the setting unit 50 (Step 1). The weft-kind information input in this step includes,
for example, information regarding whether or not the weft has elasticity such as
the kind of weft, whether or not an elasticizing process has been performed, the twist
number, etc. After the weft-kind information for a plurality of kinds of weft to be
set is input, the setting unit 50 proceeds to the next step (Step 2). In this step,
in accordance with a predetermined algorithm, the setting unit 50 determines whether
or not the weft has elasticity and sets an elasticity flag if the weft has elasticity.
If the weft has no elasticity, the setting unit 50 clears the elasticity flag. Then,
the setting unit 50 determines whether the elasticity flag is set or cleared (Step
3). If the elasticity flag is cleared (that is, if the result is 'no'), the process
proceeds to the display of a starting method selection screen and shows both the blank
beating start and the normal start in a menu of selectable starting methods (Step
4). The operator inputs one of the two starting methods being displayed (Step 5),
and the setting unit 50 displays an input screen for inputting detailed conditions
corresponding to the set starting method. Then, the operator inputs required information
(Step 6), and when the input is finished, the process proceeds to the step for inputting
weaving conditions such as weft-insertion conditions (Step 7). Then, the starting
method selecting process is finished.
[0048] If the elasticity flag is set in Step 3 (that is, if the result is 'yes'), it is
determined that the blank beating start cannot be selected and the 300° start, which
is the normal start, is set as the selected starting method (Step 8). Then, the setting
unit 50 displays an input screen for inputting detailed conditions corresponding to
the normal start, and the operator inputs required information (Step 6). Then, when
the input is finished, the process proceeds to the step for inputting weaving conditions
such as weft-insertion conditions (Step 7) and the starting method selecting process
is finished.
[0049] Thus, the information regarding the elasticity of the weft is input in advance, and
if the information input to the setting unit 50 indicates that the weft has elasticity,
the blank beating start which involves the reverse rotation is eliminated from the
list of selectable starting methods. Accordingly, the normal starting method is selected
and set as the starting method of the loom. Therefore, the operator is prevented from
selecting the blank beating start without taking the elasticity of the weft into account
by mistake. As a result, similar to the first embodiment, unlike the known system,
fabric defects caused when the blank beating start involving the reverse rotation
is executed and the weft yarn "b" having elasticity which has already been woven in
contracts by being released at the cloth fell are prevented. Therefore, a problem
in that the quality of the woven fabric is degraded for a long time until the operator
or a fabric inspector notices the incorrect setting of the starting method is prevented.
[0050] The above-described first and second embodiments may also be modified as below.
[0051] In the above-described embodiments, the 300° start is used as the normal start which
functions as the substitute starting method. In this starting method, the loom is
activated at the current drive operation position (angle 300°) and weft insertion
is started after the timing of the beat-up motion (angle 0°) is reached. However,
the drive operation position (standby angle) is not limited to 300°. For example,
it is not necessary that the drive operation position be in front of the position
corresponding to the timing of the beat-up motion, and the drive operation position
may also be set behind the position corresponding to the timing of the beat-up motion.
For example, as shown in Fig. 7, the starting method may also be such that the standby
angle at the stoppage of the loom is set to 60° and the drive operation position is
set to 60°. Then, the loom is activated from the current drive operation position,
and the beat-up motion is performed after starting the weft insertion. The reason
why this starting method may be used will be described below. When the weave pattern
is a twill weave of 2/1, 3/1, etc., the opening of the shed is at a maximum at one
of the heald frames when the angle is 300°, and therefore weft bars (wavy set marks)
due to the vertical displacement of the cloth fell are generated. In order to eliminate
these weft bars, the loom is preferably started at a main shaft angle at which the
warp shed is somewhat opened in the direction of the shedding motion so that the cloth
fell is prevented from being displaced in the vertical direction, and such a state
of the warp shed is obtained when the main shaft angle is around 60°. In this detailed
explanation, the 300° start is an example of a first start, and the 60° start is an
example of a second start. The drive operation positions (angles) of the former and
latter starts are not limited to 300° and 60°, respectively, and may be set arbitrarily
as long as the intended effects can be obtained.
[0052] In addition, in the above-described first and second embodiments, only the 300° start
is set as the normal start which is used as the substitute starting method for the
blank beating start. However, the 60° start may also be set instead of the 300° start.
Alternatively, the substitute starting method may also be selected from among a plurality
of starting methods including the 300° start and the 60° start. With respect to a
method for selecting the substitute starting method, the operator may set the starting
method to be selected in advance from experience. Alternatively, an adequate substitute
starting method may be selected automatically by analyzing data set in the setting
unit 50 such as the information regarding the kind of weft and warp, the weft density,
the weaving pattern, etc., in accordance with a predetermined algorithm, and be transmitted
to the control unit as starting method selection information.
[0053] In the above-described embodiments, preferably, other weft-bar prevention techniques
are used in combination. The other weft-bar prevention techniques may include, for
example, a technique of generating the activation preparation signal S9 when the loom
is operated and rotating the take-up roller and the warp beam by predetermined amounts
to correct the position of the cloth fell. These techniques are additionally used
when, for example, the normal start is selected instead of the blank beating start
as described above. Alternatively, these techniques may also be used irrespective
of the starting method. More preferably, the amounts of rotation for correcting the
position of the cloth fell are set to different values depending on whether the blank
beating start is set or the normal start is set.
[0054] In the circuit structure of the control unit 32 shown in Fig. 2, the main controller
34 for controlling the start of the loom and the determination unit 40 for determining
whether or not to restrict the blank beating start on the basis of the weft selection
information and the information regarding the elasticity of the weft are provided
independently of each other. However, they may also be provided as a single circuit.
In addition, the main controller 34 included in the control unit 32 may also be structured
as a circuit having additional functions of various processes of the loom regarding
the warp control unit, the feeler, etc., and all of these processes may be performed
by the microprocessor unit and a software installed in advance.
[0055] Although the embodiment of Fig. 1 shows a loom of the two-color weft insertion type,
the present invention may also be applied to looms of a single-color weft insertion
type, a three-color weft insertion type, or more. In addition, although an air jet
loom is explained in the above-described embodiments, the present invention may also
be applied to other shuttleless looms such as water jet looms and rapier looms. In
addition, the present invention may also be applied to looms having automatic repair
devices which automatically solve the cause of stoppage, such as weft insertion error
and yarn breakage of weft or warp, and restart the operation.