Title: Method for controlling the shed in a loom with fluidic weft insertion
Abstract: The shed of a fluidic weaving loom is not changed simultaneously for all warp threads, but rather continuously starting at the weft entrance and continuing helically, so to speak, to the exit of the warp shed. This sequential shed closure takes place with a so-called domino effect along a helical line curved in space, whereby additional time is gained for stretching the inserted weft thread and temporarily stopping the shed formation or shedding is avoided.
Patent Number: 6,863,091 Issued on 03/08/2005 to Wahhoud
| Inventors:
|
Wahhoud; Adnan (Lindau, DE)
|
| Assignee:
|
Staubli Faverges (Faverges, FR)
|
| Appl. No.:
|
268334 |
| Filed:
|
October 9, 2002 |
Foreign Application Priority Data
| Oct 10, 2001[DE] | 101 49 970 |
| Current U.S. Class: |
139/435.1; 139/55.1 |
| Intern'l Class: |
D03D 047//32 |
| Field of Search: |
139/55.1,59,435.1,85,93
|
References Cited [Referenced By]
U.S. Patent Documents
| 5390709 | Feb., 1995 | Martonffy | 139/456.
|
| Foreign Patent Documents |
| 0353005 | Jan., 1990 | EP.
| |
| 0697477 | Feb., 1996 | EP.
| |
Primary Examiner: Calvert; John
Assistant Examiner: Kauffman; Brian
Attorney, Agent or Firm: Dowell & Dowell, P.C.
Parent Case Text
PRIORITY CLAIM
The application is based on and claims priority under 35 U.S.C. .sctn.119
of German Patent Application 101 49 970.1-26, filed on Oct. 10, 2001 in
the Federal Republic of Germany. The entire disclosure of the German
Patent Application is incorporated herein by reference.
Claims
What is claimed is:
1. A method for controlling a warp shed in a weaving loom having a fluidic
weft insertion, a main loom drive shaft and a given weaving width, said
weaving loom further including a plurality of heddles and a respective
plurality of individually controllable heddle drives so that each heddle
has its own drive, said method comprising the following steps:
(a) allocating to said given weaving width of said weaving loom a weft
entrance (A0) at a shed entrance, a shed center (A1), and a weft exit (A2)
at a shed exit,
(b) fluidically inserting each weft thread into said warp shed from said
shed entrance to said shed exit,
(c) generating reference signals based on angular degrees of rotation of
said main loom drive shaft,
(d) providing separate heddle motion control signals for each of said
individually controllable heddle drives, and
(e) separately controlling each of said heddle drives by said separate
heddle motion control signals in response to said angular reference
signals so that a closure of said warp shed begins at said weft entrance
(A0), proceeds continuously through said warp shed past said shed center
(A1) and ends at said shed exit (A2) of said warp shed, whereby a
respective shedding motion of all heddles sequentially follows a curve
resembling a helically curved domino effect without stopping the shedding.
2. The method of claim 1, comprising applying said separate heddle motion
control signals within an angular range of 100.degree. at the most of said
rotation of said main loom drive shaft.
3. The method of claim 2, wherein said angular range of said rotation of
said main loom drive shaft is 60.degree..
4. The method of claim 1, wherein said applying of said separate heddle
motion control signals begins at about 290.degree. of one revolution of
said main loom drive shaft and ends at about 350.degree. of said one
revolution of said main loom drive shaft.
5. The method of claim 1, wherein said separate heddle motion control
signals are applied so that warp thread holders of said heddles assume a
position along a sinusoidal curve between said shed entrance and said shed
exit and along said given weaving width.
6. The method of claim 1, wherein a first shed closure point of time of a
first pair of warp threads at said shed entrance (A0), a second shed
closure point of time of a second pair of warp threads at said shed center
(A1) and a third shed closure point of time of a third pair of warp
threads at said shed exit (A2) are spaced from each other by a time
duration corresponding to 30.degree. of rotation of said main loom dive
shaft.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to U.S. Patent Application for: Method for
Controlling the Shed in a Loom With Mechanical Weft Insertion (Attorney's
Docket No. 4411); by the present inventor. The related application is
filed concurrently with the present application. The entire disclosure of
the related application is incorparated herein by reference.
FIELD OF THE INVENTION
The invention relates to a method for controlling the warp shed formation
and warp shed closure with the aid of a jacquard that is part of a weaving
loom. The weft threads are inserted into the open warp shed by at least
one fluidic nozzle. One main nozzle is positioned at an entrance to the
warp shed. Auxiliary nozzles are positioned along the warp shed or along
the fluidic weft insertion channel.
BACKGROUND INFORMATION
Weaving looms with a fluidic weft thread insertion for producing a fabric
having a predetermined fabric pattern are operated in combination with a
jacquard which controls the repeated shed formation of the warp threads.
One weaving cycle includes an opening of a warp shed, an insertion of a
weft thread into the warp shed and closing of the warp shed followed by a
beat-up of the inserted weft by a reed against the fabric. A fluidic weft
insertion by one or more nozzles such as air jet nozzles requires a
special attention to the shed formation to avoid damaging the warp threads
by the jets and to optimally control the shed formation along the weaving
width defined between a weft entrance and a weft exit of the warp shed.
A jacquard of modern construction comprises a plurality of electrically or
electronically controllable warp lifting and lowering components or drives
which, for example, are driven by controllable electric motors. Such
jacquards do not comprise any knives nor any drives for such knives.
Each warp thread of all warp threads in the loom is guided and driven by
the jacquard operating components including harness cords, etc., which
lift and lower the respective warp thread through coupling elements which
connect the harness cords with respective drives and with heddles and pull
back members to move each of the warp threads. Each harness cord and its
pull back member are guided and driven by a respective individual
operating component or drive motor in such a way that the warp shed is
formed by the warp threads. For this purpose one group of warp threads is
moved vertically from a first upper position to a second lower position
while another group of warp threads is simultaneously vertically moved
from the second lower position to the first upper position to thereby form
the warp or loom shed. An electronic control or CPU is provided for the
controlled motion of the warp threads for the shed formation and
respective shed closure. The electronic control drives each of the warp
operating components such as electric motors in accordance with a
preselected program by transmitting signals from the control unit, for
example, to the above mentioned individual electric motors for driving or
moving the warp threads for the proper shed formation also referred to as
shedding.
European Patent Publication EP 0,353,005 B2 (Palmer) discloses an example
of a weaving loom with a drive mechanism that performs the function of a
jacquard as described above. Each individual warp thread is moved by its
heddle and a respective heddle actuator between end positions which are
variable in accordance with a fabric pattern representing program stored
in the memory of a computer. The operation is such that a preselected
pattern is formed in the textile being woven. The control data stored in
the computer memory represent selected operating parameters that result in
an "oblique or parabolic shedding" during the weaving operation.
The disclosure of the European Patent Publication EP 0,353,005 B2 does not
provide for different shed formation configurations for different types of
looms such as mechanical looms with a weft insertion by two rapiers or
fluid jet looms with a fluidic weft insertion by fluid nozzles for
transporting a weft thread through the warp or loom shed having an
entrance and an exit. Thus, the shedding or the shed motion profiles for
the same fabric pattern are identical, namely oblique or parabolic for a
loom with mechanical weft insertion and for a loom with pneumatic weft
insertion. The use of either oblique or parabolic shedding in any type of
loom does not take into account that different types of looms have
different shedding requirements for achieving an optimal weaving
operation.
OBJECTS OF THE INVENTION
In view of the foregoing it is the aim of the invention to achieve the
following objects singly or in combination:
to control the shed motion profile or shedding in accordance with the
requirements of a loom with a fluidic weft insertion;
to control the motion of individual heddles in such a way that in a loom
with a fluidic weft insertion by a nozzle or nozzles, the shed motion
profile or shedding permits a safe operation of the weft insertion nozzle
or nozzles with substantially no damage to the warp threads by the jet or
jets;
to provide an increased operational life for the components that operate
the heddles including the warp pull back elements;
to reduce the wear and tear on the warp threads and of the heddle driving
components and pull back elements to thereby increase the operational life
of weaving looms with a fluidic weft insertion while gently handling or
driving the warp threads for the shed formation;
to increase the time duration of keeping a shed open in a weaving loom with
a fluidic weft insertion, in such a way that more time is available for
stretching the fluidically inserted weft thread as it passes through the
weft insertion channel as compared to the prior art;
to increase the opening time of the so-called weft insertion window in a
weaving cycle; and
to provide a gentle fluidic weft transport while simultaneously improving
the stretching of the weft thread to thereby also improve the fabric
quality.
SUMMARY OF THE INVENTION
The above objects have been achieved according to the invention by a method
which takes shedding requirements of a loom with fluidic weft insertion
into account for operating the individual heddles in a heald shaft in
response to electronic control data stored in a computer memory or
respective signals provided by a control unit. The data for individually
or separately controlling the lifting and lowering of the warp threads
take into account a safe timing that depends on the angular rotation of
the main drive shaft of the loom, for the warp thread positions relative
to influence areas of the weft inserting jet or jets along the weaving
width of the loom corresponding to the weft insertion channel length.
According to the invention the driving of the individual heddles depends
on the instantaneous angular rotational position of a main loom drive
shaft in such a manner that a shed stop is avoided entirely along the
weaving width from a weft entrance of the warp shed to a weft exit of the
warp shed, and further so that a shed closure starts at the weft entrance
and proceeds continuously and sequentially to the weft exit of the warp
shed, and so that the shedding motion of the warp threads follows a curve
that twists in space as a helix whereby a domino effect motion is
achieved.
According to the invention the heddle operating components are controlled,
following the fluidic insertion of the weft thread into an open shed, in
such a manner that over the weaving widths the shed closing for each
individual weft thread advances continuously in response to an
instantaneous angular position of the main drive shaft of the loom. Stated
differently the shed closure for each individual weft thread begins at the
weft entrance and is then shifted along the open shed from the entrance to
the exit of the shed in a continuous manner.
Thus, at the exit of the weft insertion channel the shed is closed later
than at the entrance of the shed, namely at a point of time which
corresponds to a larger rotational angle of the main loom drive shaft than
the rotational angle at the beginning of the shed closure at the weft
entrance. As a result the total shed closing time is about 25% longer than
in conventional fluidic looms, whereby this time can be advantageously
utilized to sufficiently stretch the inserted weft thread already at the
beginning of the shed enclosure.
The invention achieves the advantage not only of the just mentioned
increased time interval, but it also permits a gentle weft inserted
combined with an improved stretching action applied to the weft thread
which in turn results in an improved weaving or fabric quality.
According to a further embodiment of the invention a continuous angle of
rotation displacement within a define dangle of rotation range of the main
drive shaft of the loom is less than or at the most 100.degree.,
preferably this angular range is about 60.degree..
According to the invention the control of the operating components for
closing the shed in response to the angular rotation of the main loom
drive shaft begins at about 290.degree. at the weft entrance of the shed
which makes possible an early weft insert start and an early stretching.
The end of this angle of rotation dependent control at the weft exit of
the shed takes place at about 350.degree., whereby the stretching phase or
time duration for stretching the weft thread is maximally or rather
optimally increased as mentioned above.
More specifically, according to the present method the following steps are
performed:
(a) allocating to said given weaving width of said weaving loom a weft
entrance A0 at a shed entrance, a shed center A1, and a weft exit A2 at a
shed exit,
(b) fluidically inserting each weft thread into said warp shed from the
shed entrance to the shed exit,
(c) generating reference signals based on angular degrees of rotation of
the main loom drive shaft,
(d) providing separate heddle motion control signals for each of the
individually controllable heddle drives, and
(e) separately controlling each of the heddle drives by separate heddle
motion control signals in response to the angular reference signals so
that a closure of said warp shed begins at said weft entrance A0, proceeds
continuously through said warp shed past said shed center A1 and ends at
said shed exit A2 of said warp shed, whereby a respective shedding motion
of all heddles sequentially follows a curve resembling a helically curved
domino effect.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be clearly understood, it will now be
described in connection with example embodiments, with reference to the
accompanying drawings, wherein:
FIG. 1 shows schematically components of a loom with a fluidic weft
insertion and a shed forming jacquard which controls the shed formation
according to the method of the invention;
FIG. 2 illustrates three points along the abscissa or weaving width
including a weft entrance, a shed center, and a weft exit along the warp
shed of the loom with a fluidic weft insertion, whereby the ordinate shows
the angle of rotation of the main loom drive shaft;
FIG. 3 illustrates continuous curves representing a warp motion or shedding
profile in a weft entrance section of the loom, whereby the abscissa shows
degrees of rotation of the main loom drive shaft;
FIG. 4 illustrates continuous curves representing a warp motion or shedding
profile in a central shed section between the shed entrance and the shed
exit, whereby the abscissa shows degrees of rotation of the main loom
drive shaft;
FIG. 5 illustrates continuous curves representing a warp motion or shedding
profile in a shed exit section, whereby the abscissa shows degrees of
rotation of the main loom drive shaft; and
FIG. 6 shows a block circuit diagram for generating a reference signal or
signals based on the angular degrees of rotation of the main loom drive
shaft.
DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND OF THE BEST MODE
OF THE INVENTION
FIG. 1 shows a schematic arrangement of the components of a loom with a
fluidic weft insertion required for explaining the invention. A control
data input unit such as a keyboard 1 is operatively connected to a central
processing and control unit 2 which in turn is operatively connected to a
jacquard 3 that individually controls the lifting and lowering of heddles
4 through respective harness cords 5. The harness cords 5 run through a
harness board 6 and move the heddles 4 including warp holders 7, for
example in the form of heddle hooks or heddle eyes for the shed formation
simply referred to as shedding. At least one warp thread runs through each
heddle eye 7.
In FIG. 1 all heddle eyes 7 are shown in a position along a dotted and
slanted line extending between 290.degree. at a weft entrance and
350.degree. at a weft exit of the warp shed. These degrees represent
rotation of a main loom drive shaft shown symbolically in FIG. 6 to be
described below. A reed 8 performs a conventional weft beat-up motion,
when the shed is entirely closed at 350.degree. of one revolution of the
main loom drive shaft as indicated by the dotted and slanted line in FIG.
1. A weft inserting nozzle 8a is positioned symbolically at the entrance
of the loom shed formed by the warp threads.
FIG. 2 shows that a weaving width 9 and thus the warp shed of the loom has
a weft entrance A0, a shed center A1 and a weft exit A2. The ordinate in
FIG. 2 represents the 360.degree. of one revolution of the main loom drive
shaft. The slanted line between 290.degree. and 350.degree. of shaft
rotation corresponds to the slanted dotted line shown in FIG. 1 and
indicates the shed closure motion sequentially from the weft entrance A0
through the shed center A1 to the shed exit A2. The dashed lines A0--A0;
A1--A1 and A2--A2 represent pairs of warp threads, each pair including an
upper shed warp thread and a lower shed warp thread. These pairs of warp
threads are respectively positioned at the weft entrance A0, at the shed
center A1 and at the weft exit A2 of the warp shed. Shed closure begins at
290.degree. and ends at 350.degree. thereby covering a range of 60.degree.
of main shaft rotation. The shed closure follows actually a curve in space
rather than a straight line in a plane. The curve in space is a helix that
represents a domino effect as one pair of warp threads after the other
closes the warp shed.
FIGS. 3, 4 and 5 show shed closure curves or motion profiles as a function
of shaft rotation. FIG. 3 relates to shedding at a shed entrance with a
shed closure at 290.degree.. FIG. 4 relates to shedding at a shed center
with a shed closure at 320.degree.. FIG. 5 relates to shedding at a shed
exit with a shed closure at 350.degree.. Thus, the respective shed
closures are phase shifted in 30.degree. steps from the entrance A0 to the
exit A2 of the warp shed without any stopping of the shed formation. The
shed closure profiles assume sinusoidal curve configurations and represent
continuous shed motions without any shed stops to gain extra time for an
effective, but gentle weft stretching.
FIG. 6 shows a block diagram for generating reference signals that
represent the angles of rotation of a main drive shaft 18 of a loom 19.
The angle information is produced by a strobe generator 20. A sensor 21
feeds strobe pulses on a conductor 22 to an input of the central control 2
also shown in FIG. 1. The central control 2 generates at least three
separate reference signals R1, R2, R3 that are supplied to the jacquard 3
at three different inputs A0', A1' and A2' which are allocated to the
respective weaving width locations A0, A1 and A2, namely at the shed
entrance A0, shed center A1, and shed exit A2.
The central control 2 correlates or synchronizes the control signals for
operating the individual harness cords 5 with the reference signals. Thus,
the respective heddles and accordingly the corresponding warp threads are
moved up or down and the shed is precisely closed at the intended angular
positions 290.degree., 320.degree. and 350.degree. of the main loom drive
shaft 18 as illustrated in FIGS. 3, 4 and 5.
Although the invention has been described with reference to specific
example embodiments, it will be appreciated that it is intended to cover
all modifications and equivalents within the scope of the appended claims.
It should also be understood that the present disclosure includes all
possible combinations of any individual features recited in any of the
appended claims.
*
