U.S. patent application number 09/773802 was filed with the patent office on 2001-08-16 for method and weaving loom for producing a leno ground fabric.
Invention is credited to Czura, Peter, Hehle, Josef, Wahhoud, Adnan.
Application Number | 20010013377 09/773802 |
Document ID | / |
Family ID | 7629468 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013377 |
Kind Code |
A1 |
Wahhoud, Adnan ; et
al. |
August 16, 2001 |
Method and weaving loom for producing a leno ground fabric
Abstract
A leno ground fabric is produced over the entire weaving width
of a loom by using two heald frames each having a length
corresponding to the weaving width. The heald frames are equipped
with a multitude of lifting healds or heddles and with a multitude
of half healds or heddles that move the leno warp thread and the
ground warp threads for the shed formation over the entire loom
width.
Inventors: |
Wahhoud, Adnan;
(Lindau-Bodolz, DE) ; Czura, Peter; (Wangen,
DE) ; Hehle, Josef; (Hoerbranz, AT) |
Correspondence
Address: |
FASSE PATENT ATTORNEYS, P.A.
P.O. BOX 726
HAMPDEN
ME
04444-0726
US
|
Family ID: |
7629468 |
Appl. No.: |
09/773802 |
Filed: |
February 1, 2001 |
Current U.S.
Class: |
139/54 |
Current CPC
Class: |
D03D 49/10 20130101;
D03C 7/00 20130101 |
Class at
Publication: |
139/54 |
International
Class: |
D03D 005/00; D03C
011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 2, 2000 |
DE |
100 04 376.3-26 |
Claims
What is claimed is:
1. A method for producing a leno ground fabric having a given
weaving width, said method comprising the following steps: a)
providing a weaving loom with at least two leno heald frames each
having a frame length corresponding to said weaving width and
including a multitude of lifting healds or heddles cooperating with
half healds or heddles for forming leno loom sheds extending
entirely across said weaving width; b) supplying to said healds
first warps for forming leno warp threads; c) supplying to said
healds second warps for forming ground warp threads; d) operating
said lifting healds and said half healds for moving said leno warp
threads transversely and up and down so that each leno warp thread
alternately crosses a respective ground warp thread from one side
of said respective warp thread to the opposite side of said
respective warp thread and back again, and for lifting said ground
warp threads vertically up and down for repeatedly forming warp
sheds, and e) inserting at least one weft thread into each of said
warp sheds for weaving said leno ground fabric over the entire
weaving width of said weaving loom.
2. The method of claim 1, wherein said supplying steps are
performed by withdrawing said leno warp threads and said ground
warp threads from respective separate warp beams.
3. The method of claim 1, further comprising measuring a tension of
said leno warp threads, comparing a measured leno warp thread
tension with a rated leno warp thread tension to provide a leno
warp thread tension first control signal, measuring a tension of
said ground warp threads, comparing a measured ground warp thread
tension with a rated ground warp thread tension to provide a ground
warp thread tension second control signal, and selecting said rated
ground warp thread tension to be larger than said rated leno warp
thread tension.
4. The method of claim 3, wherein said rated leno warp thread
tension corresponds to 40% to 60% of said rated ground warp thread
tension.
5. The method of claim 1, further comprising using polymeric thread
material having a rectangular cross-section for said leno warp
threads and for said ground warp threads.
6. A weaving loom for producing a leno ground fabric having a given
weaving width, said weaving loom comprising: a leno thread supply
first warp beam, means for driving said first warp beam, a ground
thread supply second warp beam, means for driving said second warp
beam, at least two heald frames including means for operating said
heald frames, said heald frames having a length corresponding to
said weaving width, said heald frames comprising a multitude of
lifting healds or heddles and half healds or heddles cooperating
with said lifting heddles for forming leno loom sheds extending
entirely across said weaving width, a driven sley and a reed
positioned for cooperation with said heald frame, weft insertion
means positioned for inserting at least one weft thread into each
of said leno loom sheds, sensors for sensing an actual warp tension
in said leno warp threads and in said ground warp threads, and a
central loom control including at least one comparator for
comparing output signal values from said sensors with rated warp
tension signal values to provide warp tension control signals.
7. The weaving loom of claim 6, wherein said heald frame for
forming said loom sheds comprise a Jacquard mechanism including
said multitude of lifting healds cooperating with said half
healds.
8. The weaving loom of claim 6, further comprising warp thread
detouring elements for said leno warp threads and for said ground
warp threads, said detouring elements comprising at least one
carding roller, and wherein said detouring elements are positioned
between said warp beams and said shed forming heald frames.
9. The weaving loom of claim 8, wherein said at least one carding
roller comprises a first cam (6.1) for a lengths compensation of
said leno warp threads and, diametrically opposite said first cam,
a second cam (6.2) for a lengths compensation of said ground warp
threads.
10. The weaving loom of claim 8, further comprising a main loom
drive (M,17) and an eccentric cam drive (18) operatively connected
to said at least one carding roller (6) for operating said at least
one carding roller in synchronism with said main loom drive.
11. The weaving loom of claim 8, wherein said sensors for sensing
an actual warp tension are positioned between said at least one
carding roller (6) and said warp thread detouring elements (10,
10.1, 11, 20.1), and wherein said sensors comprise at least one
first sensor for sensing leno warp thread tensions and at least one
second sensor for sensing ground warp thread tensions.
12. The weaving loom of claim 8, wherein said warp thread detouring
elements comprise warp guides of rotational symmetry, said weaving
loom further comprising a warp stop motion including stop motion
rails (20.1), said rails forming part of said warp thread detouring
elements.
13. The weaving loom of claim 6, comprising at least one additional
tension sensor (9) positioned for sensing fabric tension, to
thereby indirectly measure warp tension.
14. The weaving loom of claim 13, further comprising electrical
signal conductors connecting outputs of said first mentioned
sensors to said central loom control and for connecting outputs
from said additional tension sensor to said central loom
control.
15. The weaving loom of claim 6, further comprising separate
detouring elements for said leno warp threads and for said ground
warp threads.
16. The weaving loom of claim 6, wherein said weft insertion means
comprise one of fluidic and mechanic weft insertion devices.
Description
[0001] This application is based on and claims the priority under
35 U.S.C. .sctn.119 of German Patent Application 100 04 376.3-26,
filed on Feb. 2, 2000, the entire disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates to producing a leno ground fabric on a
weaving loom modified for that purpose.
BACKGROUND INFORMATION
[0003] European Patent Publication EP 0,534,629 B1 describes a
weaving loom with a first heald frame and a second heald frame.
Each heald frame is vertically shiftable or displaceable in shaft
guides of the weaving loom. At least one of the heald frames holds
a subframe carrying heald shafts or heddles. The subframe is
movable back and forth, for example in the first heald frame, in
the weft insertion direction. For performing the back and forth
motion the subframe is slidably mounted with an axle or support bar
extending in the weft insertion direction and slidably mounted on
supports of the respective heald frame that holds the subframe. The
healds or heddles of the subframe comprise short heddles
alternating with long heddles, whereby each short heddle has the
shape of a small rail, the free end of which has a reversed head
section with a heddle eye for threading a leno thread through the
heddle eye. The subframe is hinged to the axle for tilting back and
forth between a weaving position and a warp insertion position to
facilitate the threading of the leno threads into the heddle eye.
The known loom requires a substantial effort and expense for
producing a leno fabric because in addition to the conventional
oscillating vertical motion sequence of the at least two heddle
frames, a motion sequence extending crosswise to the normal
vertical motion for moving the subframe in the weft insertion
direction is required.
[0004] European Patent Publication EP 0,369,525 B1 discloses a
method for producing a leno or so-called cross weave fabric
including at least one heald frame for the ground warp threads and
two heald frames for the leno threads. This type of loom also
requires a relatively high effort and expense for the construction
and driving elements of the three heald frames.
[0005] German Patent Publication DE 197 50 804 C1 discloses a leno
selvage apparatus for producing solid or tight selvages with the
help of two lifting heddles which are mounted on two heald shafts
of a loom. The heald shafts are alternately movable. The selvage
forming device further includes a so-called half heald or heddle
that cooperates with the two lifting heddles. More specifically,
the half heddle is alternately entrained by one or the other
lifting heald or heddle in accordance with the motion of the heald
frames. The half heddle includes two legs which merge at their
upper ends into a head formation provided with an eye for guiding
the ground thread. The production of a leno selvage with a leno
binding by means of such a combination of two long lifting heddles
with a short half heddle is known and does not require any further
description.
OBJECTS OF THE INVENTION
[0006] It is the aim of the invention to achieve the following
objects singly or in combination:
[0007] to produce a leno ground fabric having a width extending
over the entire weaving width of a weaving loom and not only over
the selvage width;
[0008] to retain the conventional shed formation by means of at
least one first and one second heddle frame for producing a leno
ground fabric that has a weaving width corresponding to the weaving
width capacity of the respective loom; and
[0009] to accomplish the warp thread motions required for the
formation of a leno ground fabric with a minimum of components,
while avoiding the use of subframes.
SUMMARY OF THE INVENTION
[0010] The above objects have been achieved according to the
invention by a method which distributes lifting heddles and half
heddles which as such are known for weaving a selvage, over the
entire weaving width of two heddle frames. According to the
invention at least two heddle frames are equipped with a multitude
of first lifting heddles for cooperation with half heddles and the
number of lifting heddles is the same in both heald frames.
Similarly, the number of half heddles is the same in both heald
frames. One half heddle will normally cooperate with two lifting
heddles. This teaching of the invention has the surprising result
that the leno binding conventionally used only for the selvage
formation is extended over the entire weaving width for producing a
leno ground fabric.
[0011] According to the invention the present loom is characterized
by at least two heddle frames equipped with lifting heddles and
half heddles as mentioned and further equipped with devices for
maintaining the required tension of the ground warp thread and of
the leno warp thread. By properly controlling the tension in the
leno warp thread and in the ground warp thread, the capacity of the
loom for the production of leno ground fabric is surprisingly
doubled compared to the prior art. For example, according to the
prior art it was possible to produce a leno ground fabric having a
width of about 2400 mm at a main loom drive r.p.m. of about 200.
According to the invention it is now possible to produce a leno
ground fabric of the mentioned width on an air jet weft insertion
loom at a main drive r.p.m. of more than 450.
[0012] According to a further aspect of the invention, the rated
warp tension of the ground warp threads is maintained to be larger
than the rated warp tension of the leno warp threads. The rated
tension of the leno warp threads corresponds to about 40 to 60% of
the rated warp tension of the ground warp thread, preferably
50%.
[0013] According to the invention, a loom is used that has either a
fluidic weft insertion with the help of air or water jets or a
mechanical weft insertion with the aid of so-called rapiers, for
example. Such looms are equipped with heald frames according to the
invention, whereby each of these heald frames carries a multitude
of lifting heddles cooperating with respective half heddles
distributed over the entire weaving width of the loom.
[0014] The shed formation components may comprise a Jacquard
machine in combination with a multitude of lifting heddles
cooperating with half heddles over the weaving width.
[0015] In a preferred embodiment of the invention the leno warp
thread is pulled off a respective warp beam over a carding roller
to provide for a length compensation in the leno warp thread.
Similarly, a length compensation is provided for the ground warp
threads, preferably by the same carding roller. The ground warp
thread is preferably pulled off a separate warp beam, but runs over
the same carding roller. For this purpose the carding roller is
equipped with two cams which are preferably extending along the
entire length of the carding roller and are positioned on the
carding roller diagonally opposite each other. The first cam
provides a length compensation in the leno warp thread. The second
cam provides a length compensation in the ground warp thread.
[0016] More specifically, the length compensation for maintaining
the desired constant warp thread tension in the leno warp thread
and in the ground warp thread, is accomplished by driving the
carding roller with its two cams through an eccentric drive in
synchronism with the shed formation or shed change. In this manner
the cams as they alternately touch the leno warp threads or the
ground warp threads, accomplish a length compensation in the sense
that a substantially constant tension force is maintained in the
leno warp threads and in the ground warp threads.
[0017] Downstream of the carding roller, as viewed in the travel
direction of the warp threads, further warp guide or detouring
elements are positioned toward the shed forming heddle or heald
frames. For controlling the tension force in the leno warp thread
and in the ground warp thread tension sensors are positioned in the
path of the respective warp threads between the carding roller and
the first detouring element. At least one such tension sensor is
provided for the respective warp threads for measuring the current
or actual warp tension.
[0018] The individual sensors are connected with their respective
output through respective electrical conductors to a central loom
control unit or CPU 16 which has stored in its memory 16' rated
warp tension signal values. A comparator 16" compares the measured
warp tension signal values with the stored rated warp tension
signal values to provide a respective control signal if there is a
deviation between the measured and the rated warp tension. The
resulting control signals, if there is a deviation, are processed
and supplied to the drive of the respective warp beam to provide a
closed loop control for the leno warp thread and separately for the
ground warp thread withdrawal to maintain the desired warp
tension.
[0019] It is also possible to measure the warp tension indirectly
so that instead of the above described warp tension sensing or
additionally thereto, at least one fabric tension sensor may be
arranged in the area of the finished fabric between the beat-up
line of the fabric and a fabric detouring device. The fabric
tension sensor measures the tension in the fabric and thus
indirectly the tension in the warp threads. The output of this
indirectly measuring fabric tension sensor is also supplied to the
central loom control to provide a closed loop control signal if
deviations between the rated and actual warp thread tensions are
discovered.
[0020] It is preferred according to the invention to provide
further guide elements between the carding roller and the shed
formation heald frames, whereby it is preferred to utilize the
rails of a warp stop motion as a warp thread detouring or guiding
element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order that the invention may be clearly understood, it
will now be described in connection with example embodiments, with
reference to the single Figure of the accompanying drawing which
shows a side view of a schematically illustrated loom equipped
according to the invention.
DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND OF THE
BEST MODE OF THE INVENTION
[0022] A loom 1 modified according to the invention comprises at
least one first heald frame 14 and at least one second heald frame
15. Heald frame 14 is equipped with a multitude of lifting heddles
14.1 extending over the entire width or length in the weft
insertion direction of the respective heald frame 14. Similarly,
heald frame 15 is equipped with an equal multitude of lifting
heddles 15.1 also distributed over the length of the heald frame 15
in the weft insertion direction. Conventional drives 14', 15' for
moving the respective heald frames 14, 15 up and down are
symbolically shown above the lifting heddles 14, 15.
[0023] Each of the first and second lifting heddles 14.1 and 15.1
cooperates alternately with a half heddle 21. Thus, the two lifting
heddles 14.1, 15.1 in their cooperation with the respective half
heddle 21 form in their distribution over the entire weaving width
within the heald frames 14 and 15, the shed formation components
for forming the loom shed 2.4 for the production of a leno ground
fabric 2.
[0024] As mentioned according to the invention, a conventional
heddle harness with its weaving healds has been replaced by at
least two heald frames 14, 15 each equipped with a multitude of
lifting heddles 14.1, 15.1 cooperating with half heddles 21 for
forming the loom shed 2.4 when weaving a leno ground fabric 2
having a fabric width corresponding to the full loom width
capacity.
[0025] From weaving leno selvages it is known that the ground
thread 2.2 passes through the eye of the half heddle 21 in a leno
selvage device. As a result, when the leno selvage shed is changed,
the ground thread of the leno selvage is relieved of tension
substantially more than the respective leno thread in the leno
selvage.
[0026] The foregoing problem has been solved according to the
invention by a special carding roller 6 provided with first and
second cams 6.1 and 6.2 for applying tension to the respective warp
thread by lengthening the travel distance of the respective warp
thread. Specifically, the cam 6.1 guides the leno warp thread 2.1
and the cam 6.2 guides the ground warp thread 2.2. Preferably, the
cams 6.1 and 6.2 are positioned on the carding roller 6 at
diametrically opposite positions.
[0027] In order to control the rotation of the carding roller 6
with its cams 6.1 and 6.2 for properly regulating the warp tension
of the leno warp thread 2.1 and of the ground warp thread 2.2, an
eccenter drive 18 for operating the carding roller 6 is coupled to
a main loom drive shaft 17 driven by the main loom drive including
a motor M. The eccenter cam 18 is so arranged that synchronization
of the warp thread tension compensation with the loom shed change
is enforced. For this purpose the carding roller 6 is coupled to
the eccenter drive 18 by coupling links 22. More specifically, the
eccenter drive 18 is so adjusted that the cams 6.1 and 6.2
alternately compensate the warp thread tension reduction resulting
form the shed change. When the warp tension is reduced the cams
6.1, 6.2 stretch the respective warp thread.
[0028] 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.
* * * * *