Textiles: weaving – Fabric manipulation – Selvage trimmers
Reexamination Certificate
2000-11-13
2001-09-11
Falik, Andy (Department: 3765)
Textiles: weaving
Fabric manipulation
Selvage trimmers
Reexamination Certificate
active
06286561
ABSTRACT:
PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 199 54 139.6, filed on Nov. 11, 1999, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to the removal of catch selvages from a fabric being woven in a weaving loom. A catch selvage is formed to temporarily bind weft ends until the wefts are beat up. Thereafter, the catch selvage is cut off and removed. The invention teaches the monitoring and controlling of the catch selvage removal.
BACKGROUND INFORMATION
It is conventional to secure or fix weft thread ends by the formation of a so-called catch selvage along the weft entrance side of the fabric and along the weft exit side of the fabric. Each selvage is formed by at least two catch selvage threads acting as warp threads, so to speak, and the weft ends projecting from the loom shed. As soon as the catch selvage has served its purpose it is cut-off a short distance from the beat-up line of the fabric. A pull-off or withdrawal mechanism for the cut-off catch selvage cooperates with detour elements for withdrawing the cut-off catch selvage and transporting it into a collecting container. If the material flow of the cut-off catch selvage or selvages is not monitored and properly controlled, the weaving process may be disturbed by ripping of the catch selvages, by winding the catch selvages onto the catch selvage withdrawal apparatus or even by winding the cut-off catch selvages or one of these selvages onto the cloth take-up beam.
German Patent Publication DE 28 20 251 (Onishi et al.) discloses an apparatus for ascertaining a failure in the withdrawal of catch selvage yarns. It is not clear from the Onishi disclosure whether the monitoring takes place after the catch selvage yarns have been formed into a catch selvage or prior to such formation. In any event, a catch selvage yarn withdrawal mechanism (10, 12) including at least one driven roller cooperating with a further roller pulls the catch selvage yarn off and out of the loom. The catch selvage yarn or yarns is pinched between the two transport rollers which rotate in opposite directions so as to apply the necessary withdrawing force to the catch selvage yarns. At least one of the two rollers is spring-biased relative to the other roller to provide the necessary friction for the withdrawal. Further, at least one of the rollers is movable away from the other in response to any accumulation of selvage catch yarns between the two rollers in order to generate a fault or alarm signal when an excess of catch selvage yarns has been accumulated between the two rollers. The fault or alarm signal is produced when the normal spacing between the two rollers is exceeded by a predetermined value. Such a mechanism is not capable of accommodating different types and sizes of weft threads and catch selvage yarn qualities on the same loom, for example thick yarns in one weaving operation and relatively thin yarns in another weaving operation which are required to be handled by the same loom for different types of fabrics.
If after a certain yarn has been used in one weaving operation and thereafter different yarns are to be used, the known apparatus, according to Onishi et al. requires a fine readjustment of the withdrawal rollers, in order to assure a proper functioning of the known monitoring apparatus for indicating a fault in the withdrawal flow of catch selvage yarns. Another drawback of the known apparatus is seen in that its response characteristic is rather slow, especially when relatively thin catch selvage yarns and relatively thin weft threads are used because a certain accumulation of yarns between the transport rollers is required before the two rollers are sufficiently separated from each other to release a fault or alarm signal. Thus, the generation of a fault signal may not occur until substantial damage has already resulted.
European Patent Publication EP 0,681,044 A1 (Meyns et al.) discloses a method and apparatus for withdrawing cut-off catch selvages. A monitoring of the flow of the cut-off catch selvage is not disclosed. However, the withdrawal rollers are provided with a friction increasing surface to assure a proper withdrawal. Further, at least one of the withdrawal rollers is so positioned relative to the other withdrawal roller that a loop of more than 150° is formed by the cut-off catch selvage around one of the rollers. However, such loop formation does not involve any monitoring to assure a proper withdrawal operation.
OBJECTS OF THE INVENTION
In view of the above it is the aim of the invention to achieve the following objects singly or in combination:
to monitor and control the withdrawal of cut-off catch selvage or selvages in such a way that any faults in the withdrawal are immediately recognized for generating a respective fault signal independently of the quality or characteristics of the weft thread and of the yarns used for forming the catch selvages;
to immediately generate and process the fault signal for producing a respective alarm and/or a control signal without delay for either stopping the loom or correcting the withdrawal; and
to use various types of sensors such as inductive, capacitive, optic, or piezoelectric sensors including sensors that respond to a change in the torque moment in any one of the electric motors that drive the cut-off selvage withdrawal rollers.
SUMMARY OF THE INVENTION
The method of the invention assures advantageously a proper withdrawal of the cut-off catch selvages by monitoring the withdrawal direction and/or the withdrawal velocity. If faults occur when the catch selvages are withdrawn during the weaving operation, these faults are measured or sensed with certainty and rapidly so that any adverse influences on the productivity of the weaving loom are either eliminated or at least minimized.
According to the invention a monitoring device is arranged downstream, relative to the movement direction of the cut-off catch selvage from the cut-off point to the collection point, of any detouring elements that guide the cut-off catch selvages to the monitoring device which signals the presence of the cut-off catch selvages in their proper withdrawal path by means of electrical signals which are supplied to an electronic processing unit which in turn provides a respective signal to the main loom control or to a separate control for the catch selvage withdrawal. Preferably such separate control forms part of the main loom control.
According to a first embodiment of the invention the monitoring device comprises a guide mechanism either stationary or in the form of rollers for the cut-off catch selvages. In the case where guide rollers are employed, these guide rollers rotate in response to the powered withdrawal of the cut-off catch selvages by means of a catch selvage withdrawal apparatus including respective drive motors. Either the rotation direction forward or backward and/or the rotation speed of the guide rollers is monitored or sensed by a respective sensor arrangement, whereby the resulting electrical signals are processed and evaluated in the electronic processing unit that is preferably part of the main loom control. At least one sensor mechanism is provided for each guide roller. In a preferred embodiment the sensor mechanism includes at least one marking on the respective guide roller and at least one sensor positioned in a fixed location opposite of the marking for sensing the marking as the marking on the rotating roller passes the respective sensor thereby producing a corresponding electrical signal or impulse.
The marking on the guide rollers must be so-constructed that the corresponding sensor can respond with certainty to the appearance of the marking. Thus, preferably inductive, capacitive or optical sensors are used in the embodiments in which markings are provided on the rotating guide rollers. Such sensors may, for example be inductively responsive sensors for example a Hall sensor, optical reflector sensors, or capacitive sensors. An
Armbrust Matthias
Birk Michael
Falik Andy
Fasse W. F.
Fasse W. G.
Lindauer Dornier Gesellschaft mbH
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