| Flexibility,
quality and ergonomics – the criteria for further development NEW TECHNOLOGY ON THE DORNIER AIR JET WEAVING MACHINE |
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| Flexibility,
quality and ergonomics – the criteria for further development NEW TECHNOLOGY ON THE DORNIER AIR JET WEAVING MACHINE |
|
| During the last few years,
the flexibility and handling of the DORNIER Air Jet have been continuously improved
through many new developments. Today, styles are woven on this machine that prior to this
series of developments would have been unthinkable. Previously it was thought that such
styles could only be woven on tape rapier or projectile machines. This article deals with those areas where these developments have been applied and how they have influenced the performance of the machine. Today, filling feeders are available featuring a separation of the individual windings of the filling on the drum, with the distance between the windings being adjustable. In order to ensure that the filling is handled carefully, the feeder has the capability of winding the filling on the drum in the S or Z direction. In addition, these feeders are equipped to monitor the filling on their input side independently of the yarn tension. All settings can be carried out on the main keypad of the weaving machine. Due to this improvement, hairy filling yarns, such as Taslan, or plied woolen yarns in counts up to Nm 10/2 can be woven with the same degree of process security as high twist or coarse yarns, up to and including 330 tex glass roving. The electronically-controlled filling tensioner keeps the peak tension value low at pick arrival and shortens the stretch time. The deployment of this device results in higher weaving speeds with high twist or low tensile strength filling yarns.
A further increase in the precision of the subnozzles has resulted in improvements in directing the jet of air. Work has also been carried out on the outer surface of these nozzles and additionally also their thickness. Together, these developments improve the processing of filament warps and delicate air entangled yarns by preventing damage to the yarn and marks in the fabric. Various configurations and types of subnozzles further increase the range of application. One example is the double configuration of the subnozzles that significantly contributes to the success achieved in weaving high twist filament yarns and coarse short staple fiber yarns.
Right at the outset, the concept for the compressed air installation should have included a provision to ensure that the equipment is correctly and securely installed. However, this does not preclude the possibility that one or other of the components could malfunction, or that a problem in the distribution network could occur at some point. Either way, this could lead to pollution of the compressed air, and this could be supplied to the weaving machine. As a preventive measure aimed at avoiding a valve malfunction resulting from impurities in the air supply, DORNIER offers a high performance microfilter, equipped with a display indicating the degree of impurities contained in the air being supplied. This can be installed on every weaving machine. During the last few years, both handling and flexibility have been further improved by deploying certain electronically-controlled and independently-driven devices on the machine. One application is the filling scissor. The timing of the scissor can be adjusted during the weaving process. It is intentionally designed to be easily reset in cases where a change in reeded width is required. The selvedge cutter, for outside and center selvedges, utilizes the same system. These can also be freely adjusted in the most advantageous position necessary from the weaving standpoint. The introduction of the new Disc-O-Leno® device (see Insider No. 6) provides for increased flexibility, higher speeds and better quality. By eliminating the necessity of two harness frames for the leno selvedges, the harness for the ground weave is moved forwards. This results in less stress on the warp sheet and reduces any tendency for the ends to cling. Consequently the stop levels during the weaving process are reduced. Also the potential range of application for the machine is increased, since for the first time patterns using the maximum capacity of 16 harness frames can be woven. When working with a lower number of harness frames, eliminating the necessity of two harness frames for leno selvedge formation means that higher weaving speeds can be achieved since the speed limit of the shedding motion has not been reached. In contrast with conventional leno devices, the disc leno device works with the same shed height as used for the ground shed. On the insertion side, the device can be timed to open the shed earlier, independently from the main shed opening. As a result, there is a bigger window for filling insertion and a more reliable functioning of the automatic pick removal and restart device AFR, while at the same time, a higher weaving speed is possible with no increase in yarn stress. In jacquard weaving, the harness cords for the leno device are eliminated and thus any changes in reeded width are simplified. A main reason that the potential speed of the air jet machine can be fully utilized, is the replacement of failure prone mechanical devices, with the Disc-O-Leno® that essentially consists of a disc driven by a stepping motor. Following the same philosophy, the pneumatic tucking device, PneumaTucker® for outside and center selvedges, also contributes to the full utilization of inherent machine performance. In an article published in ”Industrial Textiles“ magazine (March 1997 issue), Mr. G. Mayer, Plant Manager of Spinnweberei Uhingen GmbH, a spinning and weaving company in Uhingen, Germany, outlines his positive practical experience with the PneumaTucker® that is used on DORNIER air jets with a nominal width of 190 cm, quoting weaving speeds of 860 ppm.
The DORNIER Air Jet incorporates an unique combination of features assuring the production of the highest quality of fabric: • sley drive from both sides by means
of conjugated cams These features are supplemented by a software package that helps to avoid start marks by instigating the following measures which can be activated through the keypad on the main display: • automatic leveling of the harness at
a machine stop, Through all these developments, the quality of fabrics produced on DORNIER air jet weaving machines has been significantly improved and the range of application for air jet weavers increased. |
The main nozzle now has the capability to handle 8 filling colors or yarn
types. The range of application stretches from fine filament yarns for labels to throws
using Ne 4.5/2 cotton filling. By optimizing the air flow in the main nozzle, untwisted,
air entangled and textured filament yarns can be inserted as a result of the more gentle
acceleration achieved through this development.
The filling insertion system is precisely monitored in order to attain the
highest degree of functional security. The release time of the main nozzle and timing of
the subnozzles are constantly measured and checked for any unacceptable variations. The
failure of a magnetic valve, either for the main nozzle or a grouping of subnozzles, is
immediately detected before this adversely affects the performance of the machine, or
indeed the quality of the fabric. A message in clear text is displayed on the main screen
of the machine, indicating the failure.
The new large scale color
display is much simpler to use, due to the fact that it contains fewer sub-menu functions.
In addition, information regarding various machine settings is easier to obtain via ”quick
access keys“ on the keypad. Colored graphical displays of individual pick flight
times, for each filling color or type, are very clearly displayed and thus much easier to
check. Also mechanical settings, for the warp stop motion, whip roll assembly and shed
formation, to name just a few, are displayed and can be called up by style. Transfer of
information and also any updating of the software package is economically performed by
means of diskette.