Textiles: weaving – Weft manipulation – Lays or beat-ups
Reexamination Certificate
2000-05-30
2001-05-15
Falik, Andy (Department: 3741)
Textiles: weaving
Weft manipulation
Lays or beat-ups
C139S026000, C139S190000
Reexamination Certificate
active
06230758
ABSTRACT:
PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 199 24 627.0, filed on May 28, 1999, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to a method for controlling the back and forth motion characteristic of a sley shaft for driving a reed in a weaving loom, particularly a pile fabric or terry cloth weaving loom. The motion of the sley shaft is derived from a cam drive disk driven by the main loom drive shaft and driving a cam follower connected to the sley shaft.
BACKGROUND INFORMATION
German Patent Publication DE 41 11 405 C2 discloses a drive for the sley of a loom by means of bellcrank levers which are movable by an eccentric cam drive disk. One end of the bellcranks is journalled to the sley and the other end is journalled to the loom frame. This type of conventional bellcrank drive is intended to achieve a high operational speed even in large looms while still providing a sufficient time duration for the rest position of the sley for proper weft insertion.
The disclosure of the just mentioned German Patent Publication achieves this purpose in that the shaft that drives the cam disk is driven by a drive motor which is controllable in its r.p.m. in such a way that the shaft rotates at a higher r.p.m. when the sley is to be moved from its beat-up position along the beat-up line of the fabric into the retracted rear position and also when the sley is moved from the rear position to the beat-up position. By accelerating the sley motions in both directions the time duration for the rest position of the sley and reed is extended when the sley is stationary due to the configuration of the cam disk, the drive shaft rotates at a lower r.p.m. namely in the range of rotation when the sley is at rest.
According to the above conventional sley movement control it is important that the shaft which drives the cam disk is controllable in its r.p.m. by controlling the shaft drive motor.
It is further important that the time duration for the forward and backward move of the sley can be shortened by the higher drive r.p.m. to thereby provide the required extended rest time duration for the sley and reed.
Such a motion sequence of the sley, namely fast stop fast, is detrimental to the weaving of so-called pile fabric or terry cloth because a uniform pile formation is adversely affected by such motion sequence. This is so because a fast moving reed which is connected to the sley, necessarily cannot on its way to the beat-up line entrain the weft thread or a group of weft threads in a gentle manner. As a result of the relatively high speed of the reed during its beat-up motion toward the beat-up line the pile warp threads that must be formed into loops are at least partially pulled out of the weft thread group, whereby the resulting loops or piles have different lengths. If such a fabric is subsequently passed through a shearing operation, the loops or piles of smaller lengths are not cut by the shearing knives so that the appearance of the fabric is non-uniform. In other words, the terry cloth has a non-uniform appearance.
Another undesirable result of the high speed entrainment of the weft threads or weft thread groups by the reed is seen in that breaking of the warp threads and/or of the weft threads occurs frequently particularly of the base warp threads as well as of the pile warp threads.
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 avoid damage to the warp threads and to the weft threads by controlling the beat-up motion of the reed in a loom, particularly a terry cloth weaving loom;
to control the motion sequence imparted by a sley drive to the reed in such a way that the reed motion toward the beat-up and the beat-up itself do not damage the weft threads, nor the base warp threads, nor the pile warp threads;
to avoid the formation of piles or loops of different heights in a terry cloth or pile fabric by making certain that all piles or loops have a uniform height or length;
to shape the cam disk for driving the sley shaft through a cam follower in a loom for weaving terry cloth in such a way that a smooth pile or loop formation is assured for weaving high quality terry cloth or pile fabric having a uniform appearance;
to drive the cam disk with a constant r.p.m. independently of whether the drive motor for the shaft that rotates the cam disk, can be or cannot be controlled in its motor r.p.m.; and
to impose a discontinuity into the deceleration of the reed as it moves toward the beat-up line whereby the deceleration may be slowed down temporarily or briefly discontinued altogether to provide a constant reed velocity at the time of the weft entrainment.
SUMMARY OF THE INVENTION
The method according to the invention for controlling a motion characteristic or curve of a sley shaft and thus of the reed in a loom, particularly a loom for weaving terry cloth or pile fabric, is performed in a loom having a main loom drive shaft that drives a cam drive such as a cam disk which in turn cooperates with a cam follower connected to the sley shaft. The present method is characterized by the following steps:
a) driving the sley shaft through said cam drive;
b) first accelerating the sley shaft from a zero velocity in a return rotation direction to a first maximum for returning the reed into a rear position opposite a beat-up position following a beat-up motion of the reed;
c) first decelerating said sley shaft to a first rotation reversal point;
d) first reversing said rotation direction and providing a reed rest period for a weft insertion;
e) second accelerating said sley shaft in an opposite beat-up direction to a second velocity maximum; and
f) second discontinuously decelerating said sley shaft in at least a first deceleration phase and a second deceleration phase, wherein said first deceleration phase extends between a first angular position where said second velocity maximum is reached and a second angular position where said reed is entraining an inserted weft or group of wefts for beat-up, and wherein said second deceleration phase extends from said entraining of said weft to a beat-up of said weft at a beat-up line of the fabric.
The second acceleration according to the invention for starting a new beat-up motion of the sley shaft and thus of the reed takes place out of the rest position in which the sley shaft and reed are in the rearmost position. The second acceleration takes place during an angular range of more than 1° to a second return velocity maximum whereupon the angular velocity of the sley shaft is controlled or rather decelerated in a discontinuous manner until the beat-up or forward end position of the reed is achieved at which point again a reversal of the rotational direction takes place. The second velocity maximum is preferably reached within an angular range of less that 160° of a full 360° revolution of the drive cam disk, whereupon the forward motion of the sley shaft and the reed are decelerated to a point where the weft or a group of weft threads are entrained by the reed and following that point further deceleration is applied to complete the beat-up. This discontinuous control of the deceleration of the sley shaft and reed on their way to the beat-up line makes sure that the weft or weft thread group for forming the pile or loops is entrained with a reduced angular velocity or even a constant angular velocity of the reed if the deceleration is not merely slowed down but is briefly fully interrupted.
This discontinuous reduction of the angular velocity of the reed on its way to beat-up in at least two phases has the following advantages. A high quality fabric appearance, particularly of terry cloth is achieved simultaneously with a loom structural advantage that a control of the dancing or looping roller for maintaining the pile warp tension is no longer necessary. According to the invention the deceleration according to the invention permits
Finger Rainer
Kimmel Stefan
Krumm Valentin
Falik Andy
Fasse W. F.
Fasse W. G.
Lindauer Dornier Gesellschaft mbH
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