Textiles: weaving – Weft manipulation – Weaving with stationary weft supply
Reexamination Certificate
2000-04-19
2001-06-05
Falik, Andy (Department: 3741)
Textiles: weaving
Weft manipulation
Weaving with stationary weft supply
C242S129800, C242S419200, C242S421200, C139S106000, C188S065300
Reexamination Certificate
active
06240974
ABSTRACT:
PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 199 17 952, filed on Apr. 21, 1999, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The tension of catch selvage yarn in a weaving loom is kept substantially constant by a brake mechanism effective on the catch selvage yarn supply spool.
BACKGROUND INFORMATION
It is known to influence and maintain the tension of catch selvage yarns in a loom in various ways. Without such efforts the tension changes as the yarn is withdrawn from the selvage yarn supply spool. The yarns are supplied by a so-called selvage spool rotatably mounted in the loom frame for producing the catch selvage of a fabric. The catch selvage is later cut off. The selvage yarn spool, hereafter referred to as supply spool, carries the selvage yarn wound onto the spool and the yarn diameter of the spool diminishes or becomes less and less as the yarn is used up during the weaving process. The yarn content or the diameter of the yarn wound onto the supply spool is sensed by a yarn follower roller. The tension on the yarn as it is pulled off the supply roller is influenced by a braking action, whereby the yarn follower roller and the brake components follow the variable diameter of the yarn coil wound onto the supply spool in response to a spring action. The follower roller and the brake components operate in synchronism.
It is known to influence and maintain a desired tension force on the catch selvage yarn or yarns with the aid of at least one so-called looping brake as shown in present
FIG. 1
to be described in more detail below. These catch selvage yarns are pulled off the supply spool during weaving by the tension applied to the selvage yarn. The looping brake controls the rotation of the supply spool and thus the tension force on the yarn. These conventional looping brakes comprise a spring tensioned brake tape or belt that loops around a supply spool flange, whereby so-called tension peaks in the selvage yarns and respective yarn breaks are unavoidable. A desired constant tension cannot be applied to the selvage yarns and yarn breaks cannot be reduced with the help of a looping brake so that there is room for improvement in such a conventional looping brake system.
German Patent Publication DE 2,421,748 C2 (Kovar et al.) discloses an apparatus for equalizing the tension on two binding threads in a leno selvage device also employing a looping brake.
German Patent Publication DE OS 2,129,817 (Mullekom) discloses a thread brake for maintaining a constant thread tension in the leno threads of a leno device for forming a leno selvage in a fabric. The Mullekom thread brake includes a bail that reaches around the flange of the leno thread spool. The bail is mounted at the end of a mounting arm the other end of which is pivotably mounted between two support lugs on the leno disk. A sensor or follower roller is provided on one side of the bail and a tension spring connected to the mounting arm of the bail is effective to keep the follower roller in contact with the thread supply on the leno thread supply spool. Brake elements are provided on the bail for keeping the leno thread tension constant. These brake elements are effective on both sides of a flange of the leno thread supply spool. Such a structure has the disadvantage that the braking elements are effective directly on the flange of the leno thread supply spool which damages the spool body in a relatively short time to such an extent that the spool body must be replaced. The damage manifests itself in so-called brake track grooves which, when the spool body is reused or refilled with leno yarn, the yarn becomes entangled in the brake grooves when thread is being pulled off the supply spool, particularly on the yarn facing side of the spool flange, whereby the thread can get caught and stuck to eventually tear.
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 provide a brake mechanism for a catch selvage yarn supply spool which will advantageously control and maintain constant the tension in the catch selvage yarns during weaving of a fabric even if the production of the catch selvage is periodically interrupted;
to apply a brake action to the supply spool in such a way that the thread tension is maintained constant even if the volume of selvage yarn still on the supply spool diminishes during weaving;
to gently apply the braking action to the supply spool without damaging the spool nor the selvage yarn or yarns;
to realize a breaking force that remains constant during the entire payout of selvage yarns from the time the full spool starts to reel off yarn until the time the spool is empty;
to avoid tension peaks on the selvage yarn during the payout from the supply spool; and
to apply the braking force to an easily exchangeable brake element that rotates in synchronism with the supply spool.
SUMMARY OF THE INVENTION
The above objects of the invention have been achieved by an apparatus for controlling the tension of catch selvage yarns in a loom including a loom frame member. The apparatus according to the invention is characterized by the combination of the following features. A selvage yarn supply spool for dispensing selvage yarn from the supply spool is rotatably mounted by a spool shaft to the loom frame member. Preferably, the supply spool is rotatable relative to the spool shaft. However, the spool shaft may be rotatable relative to the frame member. In both instances, the rotation is about a spool axis in response to the pull applied to the yarns being reeled off the spool. A yarn follower for contacting the supply of catch selvage yarn on the supply roller is secured through a yarn follower mounting to the loom frame member. Either the yarn follower is rotatable relative to its mounting or the mounting is rotatable relative to the loom frame member. The present brake mechanism comprises a first brake member rotating with the supply spool and a second brake member operatively secured to the yarn follower mounting for rotation or tilting in synchronism with the yarn follower so that the second brake member on the one hand responds to the motion of the yarn follower and on the other hand cooperates with the first brake member in applying a constant braking action to the supply spool in response to the instantaneous radial position of the yarn follower, whereby the second brake member follows in synchronism the motion of the yarn follower. More specifically, as the yarn supply on the supply spool diminishes, the yarn follower moves radially inwardly of the supply spool and so does the second brake member.
In the preferred embodiment the first brake member is a replaceable brake disk that is mounted on the shaft that also carries the selvage yarn supply spool. The brake disk is rigidly engaged with a spool flange for synchronous rotation with the supply spool on the one hand while the second brake member that faces one side of the brake disk can move radially relative to the brake disk in response to the motion of the yarn follower which preferably is a follower roller in contact with the yarn on the spool. Thus, a constant brake force is applied to the spool and to the yarn at all times during yarn payout.
An advantageous embodiment of the invention employs a torsion spring for assuring proper contact between the yarn follower roller and the diminishing yarn supply on the spool. One end of the torsion spring engages, for example, the loom frame member while the other end engages a lever arm or mounting arm that carries at its free end the yarn follower roller.
An important advantage of the invention is seen in that the tension on the selvage yarn remains constant at all times during payout of yarn from the spool from the beginning of the payout until the spool is empty. Thus, tension peaks on the catch selvage yarns are avoided, which in turn has the advantage that yarn breaks are substantially avoided, taking
Falik Andy
Fasse W. F.
Fasse W. G.
Lindauer Dornier GmbH
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