This application claims priority from PCT application No. PCT/EP2017/064312 filed Jun. 12, 2017 which claims priority from European application No. EP16174607.8 filed Jun. 15, 2016, the disclosures of which are incorporated herein by reference.
The invention relates to a ribbon needle weaving loom. Moreover, the invention relates to corresponding weaving methods.
Ribbon needle weaving looms are used for weaving ribbons, usually with widths of up to approximately 40 cm, and they insert the weft thread into the open shed by means of a weft needle. Such a weaving loom, in which as usual the drive of the weft insertion needle is connected to the main shaft of the weaving loom by means of mechanical coupling, is known from CH 633 331 A. Thereby, it is essential that the weaving cycle, that means, the shed forming and the motion of the reed for the purpose of stopping the fabric, occurs synchronously with the weft insertion, for which purpose it has already been proposed, for example in WO 2004/092 467 A, that the shed forming may be provided, depending on the operating state of the weaving loom, with a “hard”, i.e. strictly synchronized synchronization device, and with a “soft” synchronization device allowing for a certain degree of preceding or trailing of the shed forming. However, the weft insertion is always provided as “hard” synchronization also with the just mentioned weaving looms because the weft needle must always find an open shed for its entire insertion time. Thereby, weft insertion needles of a ribbon weaving loom usually make a crescent-shaped motion, which—as described in CH 633 331 A—originates from the reciprocating pivoting motion derived from the main shaft. However, for certain applications, this type of weaving loom wherein the drive of the weft insertion needle is derived from the main shaft of the weaving loom reaches certain limits. Such type of application is the production of ribbons with varying bandwidth. In such a weaving loom, the transition from a larger width to a smaller width and vice versa results in unappealing weave regions, which are perceived as flawed by the person skilled in the art, if the weft needle always travels along the same weft insertion path independently of the width of the woven ribbon. This is because—particularly in the transition region between a larger to a smaller and from a smaller to a larger ribbon width—the weft thread tension cannot be kept constant in a simple manner. In another typical application with ribbon needle weaving looms, in which the conventional crescent technique is used wherein the weft needle motion is more or less rigidly driven by the main shaft, various weft threads—typically threads with different colors, but also threads with different material properties—are selected by a single weft needle. Also here it seems problematic to maintain a uniform weft thread tension for the different threads, which in fact are picked up from different positions. In certain applications of ribbon needle weaving looms, the starting time of the weft needle insertion motion is furthermore particularly critical. This is the case, on the one hand, for example in a stitch-like insertion of an additional thread such as an antenna thread according to EP 2395140 A1 or WO 2007/071077 A1, or of an effect thread such as in EP 3141642 A1, and on the other hand, also quite generally, when the warp threads cannot be separated quickly enough during a change of the shed so that the weft insertion cannot be carried out precisely during the change of the shed. The latter problem could actually be solved, in principle, with an increased shed stroke or with a significantly reduced weaving speed; but this solution is partly undesirable for various reasons. A generic ribbon needle weaving loom is, furthermore, described in EP 1526199 A1.
The object of the invention is to configure a weft insertion in a ribbon needle weaving loom in such manner that the path of the weft insertion needle as well as the starting time point of the weft insertion can be varied as freely as possible without the requirement of complex transmission arrangements between the main shaft and the driving of the weft insertion needle.
This object is achieved by a ribbon needle weaving loom as described herein. Thereby, the measures of the invention initially lead to an unexpectedly high level of flexibility. Due to the fact that the control unit for controlling the driving motors for the weft insertion needle is configured in such manner that the targeting of a predetermined insertion end position and a return end position of the weft insertion needle can be selected in practically free manner for each weft insertion, an optimal insertion path of the weft needle is programmable for each one of varying bandwidths, wherein, for example, upon transition to another width of the woven ribbon the weft thread tension can be kept uniform. The problem arising with different weft threads to be selectively picked up by the weft needle is solved by the measures of the invention in the same or a similar manner. It is apparent that with a weft insertion actuator which is programmable by the control unit, either as a rotary drive or as a linear drive, also the starting time point and also the insertion speed, not only the path of the weft insertion needle, can be predetermined. In particular, with additional threads that are inserted into the woven material by means of reed hooks or the like, the critical edge conditions can be taken into consideration. In the present context, the term “weft thread loop” shall designate the section of the weft thread which is to be incorporated from the insertion side all the way to the knitting device and back into the warp threads.
The electromechanic actuator of the ribbon needle weaving loom according to the present invention can advantageously be configured as a rotary drive, preferably as servo motor or as stepper motor, whereby the weft insertion needle is firmly connected to the axis of the rotary actuator through a band or pulley drive or through a crank drive. For this purpose, the rotary actuator can either execute the motion of a vibration in form of a motion back and forth about a certain angle and thus be connected with the weft thread insertion needle directly or, for example, through a band or pulley drive (for example, as a transmission gear or reducing gear) or it can execute a complete circular motion and then, for example, execute the motion of the weft thread insertion needle through a crank drive. It is particularly advantageous—at least for certain applications—if the electromechanic actuator is configured as a linear drive—also preferably as a servo motor or stepper motor. In this case, it is possible to have, instead of the crescent path generally used for weft insertion needles, a straight i.e. geometrically short weft insertion needle path—preferably aligned perpendicularly to the warp threads. In this case, it can be provided—as a rigid, but simplest solution—that the weft thread insertion needle is firmly connected to the lifting axis of the linear actuator, alternatively through a band or pulley drive or by means of a pushrod, toothed rack, pinion or a lever drive. Indeed, the latter embodiments are particularly advantageous when the drive is connected to a plurality of synchronized ribbon weaving units, which are preferably arranged adjacent to each other, each having one weft thread insertion needle. To relieve the actuator, it may be advantageous if the actuator and the weft thread insertion needle form together with the two restoring springs of a restoring spring arrangement a spring/mass system. It may be advantageous if the ribbon needle weaving loom comprises means for producing a ribbon with varying width, wherein such means may comprise, in particular, Y-shaped reeds which are preferably adjustable in height. It can be advantageous if the ribbon needle weaving loom comprises means for picking up and depositing weft threads of various type, for which purpose advantageous means are described, for example, in WO2012/163571 A2. The aforementioned elements as well as those claimed and described in the following exemplary embodiments, to be used according to the invention, are not subject to any particular conditions by way of exclusion in terms of their size, shape, use of material and technical design, with the result that the selection criteria known in the respective field of application can be used without restrictions.
Further details, advantages and features of the object of the present invention will become apparent from the following description and the corresponding drawings, in which ribbon needle weaving looms and their weft thread insertion units according to the present invention are illustrated by way of example. In the drawings there are shown in:
In
s(t)=A*sin(ω0*t) A=oscillation amplitude [m], t=time [sec]
Frictional forces dampen the vibration, so that it subsides and finally comes to a standstill. The natural frequency substantially depends on the moving mass and the spring constant and is calculated according to the formula:
ω02=c/m c=spring constant [N/m], m=total moving mass [kg]
Ideally, the system is tuned such that the frequency of the main shaft rotation in the production mode coincides with the natural frequency of the weft insertion system. The linear actuator 30a then only has to overcome the frictional forces and to correct small frequency deviations. In this way, a very low-energy operation of the weft insertion system is possible. As soon as the main shaft rotational frequency falls below the natural frequency of the weft insertion system and/or the shape of the motion of the weft insertion system shall deviate from the pure sine curve, the linear actuator must apply higher forces for the synchronization of the motions because it must counteract or support the natural frequency. Provided that the friction in the vibration system is not excessive, the maximum force to be applied by the linear actuator Fmax=c*A occurs when the weft needle must be held in one of its end positions when the machine is stopped.
In
This situation is now accessible to the improvements of the present invention, which will be shown in various applications.
As a first application example, the delayed shed insertion angle of the weft thread insertion needle 10 will be explained with reference to
In the end, the security against understitching—that is, an insertion while a warp thread is still in a wrong position, which results in a weaving fault—is significantly increased. Even more significant is the advantage for a stitching weaving loom comprising, for example, a reed hook for the insertion of additional threads. In such a stitching weaving loom, the stitching needle must be immersed into the lower shed before the weft needle inserts into the shed. Since the immersion movement of the stitching needle is very time-critical (high accelerations), a delayed insertion of the weft needle allows for higher speeds.
As a further application example, the weft thread change will be explained with reference to
The further application example for the present invention is explained in the
In principle, a continuous safe operation could be guaranteed with a stepper motor in the actuator 30 or 30a, but with a servo motor it seems reasonable to ensure that the control and thus the motion of the weft thread insertion needle remain in the desired phase. This can be ensured with a control—as shown in
Of course, the possibilities to optimize the ribbon needle weaving loom by means of control do not end here. For example, it is possible to optimize the weaving speed by selecting, for example, the delay Δα (
4 warp threads
8 shed
9 woven material
10 weft thread insertion needles
10
a thread receiving at the weft thread insertion needle
10
b last weft thread loop
11 axis of the weft thread insertion needle
14 weft thread and 1st weft thread, respectively
14
a thread guiding eye
15 2nd weft thread
16 3rd weft thread
17 4th weft thread
18 weft thread transport
18
a weft thread eye
18
b weft thread tension spring
19 weft needle fork
20 reed
30 rotary actuator
30
a linear actuator
32 control device
34 band or pulley drive
36 crank drive
38 pushrod
40 band with variable width
50 restoring spring arrangement
52 restoring spring
54 restoring spring
100 control loop
110 rotation angle measuring device
A1 weft thread guide 1st weft thread
A2 weft thread guide 2nd weft thread
A3 weft thread guide 3rd weft thread
A4 weft thread guide 4th weft thread
Number | Date | Country | Kind |
---|---|---|---|
16174607 | Jun 2016 | EP | regional |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2017/064312 | 6/12/2017 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2017/216117 | 12/21/2017 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
1296024 | Waite | Mar 1919 | A |
3064689 | Piazzolla | Nov 1962 | A |
3104683 | Weiner | Sep 1963 | A |
4305434 | Muller | Dec 1981 | A |
4577665 | Diesner | Mar 1986 | A |
5411064 | Yamagishi | May 1995 | A |
6962172 | Zorini | Nov 2005 | B2 |
7451787 | Speich | Nov 2008 | B2 |
10526731 | Podhajny | Jan 2020 | B2 |
20070119142 | Buhler | May 2007 | A1 |
20130118633 | Studer | May 2013 | A1 |
20180363170 | Borer et al. | Dec 2018 | A1 |
Number | Date | Country |
---|---|---|
633 331 | Nov 1982 | CH |
1526199 | Aug 2007 | EP |
2395140 | Dec 2011 | EP |
3141642 | Mar 2017 | EP |
2004092467 | Oct 2004 | WO |
2007071077 | Jun 2007 | WO |
2012163571 | Dec 2012 | WO |
Entry |
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“Needle Weaving Technology in Narrow Fabrics Series of Text Books for the Narrow Fabrics Industry”, vol. 2, Jakob Muller Institute of Narrow Fabrics. |
English translation of International Search Report in related PCT/EP2017/064312. |
English translation of Written Opinion of the ISA in related PCT/EP2017/064312. |
Number | Date | Country | |
---|---|---|---|
20190264355 A1 | Aug 2019 | US |