Textiles: weaving – Warp manipulation – Traversing
Reexamination Certificate
2001-02-01
2001-11-06
Falik, Andy (Department: 3765)
Textiles: weaving
Warp manipulation
Traversing
C139S052000, C139S054000
Reexamination Certificate
active
06311737
ABSTRACT:
PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §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
The invention relates to producing a leno ground fabric on a weaving loom modified for that purpose.
BACKGROUND INFORMATION
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.
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.
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
It is the aim of the invention to achieve the following objects singly or in combination:
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;
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
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
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.
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.
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%.
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.
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.
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.
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.
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.
The individual sensors are connected with
Czura Peter
Hehle Josef
Wahhoud Adnan
Falik Andy
Fasse W. F.
Fasse W. G.
Lindauer Dornier Gesellschaft mbH
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