New Horizons In Dobby & Jacquard Weaving
Dornier's SyncroDrive® system helps eliminate the problem of stop and start marks and allows freely programmable weft insertion for dobby and Jacquard fabrics.
Jürg Rupp, Executive Editor
For decades, the global weaving community has waited for a system that would prevent problems, in particular, during starts and stops. Germany-based weaving machine manufacturer Lindauer Dornier GmbH's SyncroDrive® might be the solution.
Up to now, a dobby or Jacquard machine has always been connected with the weaving machine. Every weaver knows the problems with high-speed weaving. Stop-and-go is just one problem; marks in the fabric after a stop or a restart contribute to inferior-quality products.
Any inconsistency in the process causes problems: The higher the speed of the propeller shaft during production, the higher the forces. The wider the machine and the greater the distance between the harnesses of the Jacquard machine, the greater are the vibrations on the entire system.
For the first time, there is a possibility to separate the weaving machine from the dobby or Jacquard machine, which means there is the possibility of an independent shed. All limits are eliminated in weaving because the weft insertion is freely programmable.
SyncroDrive is a patented, low-maintenance drive system that has no clutch-brake unit and has a separate motor for the shedding device. Thanks to the intelligent drive design, speed fluctuations are extremely small compared to conventional direct drives.
SyncroDrive reads the desired weft insertion and stores it. The last weft insertion remains memorized during the next startup. The Jacquard machine's shed formation speeds up, for example, over eight to 10 insertions to reach the specified speed. Similarly, the weaving machine speeds up over one weft insertion to reach the specified speed. The synchronization of the two machines starts when both have reached the specified speed. Then, the true weaving process - the weft insertion - begins. If the job is completed or stopped, the last insertion is memorized while the machines shut down. The shed formation shuts down to a full stop over eight to 10 insertions. The weaving machine shutdown is carried out over one weft insertion.
In production, the timing of the shed closing can be adjusted electronically by the Dornier ErgoWeave®, and the data can be stored and product reproduced. The minimum stress of the dobby/lace system further ensures longer life of the mechanical elements and thus better product quality.
In traditional weaving production, the weaving machines and the shedding device must be accelerated in parallel, which requires very high power usage (See Figure 1). The servo motors used in SyncroDrive meet all EFF1 energy efficiency classifications or the new, somewhat equal, International Efficiency classification (IE2). EFF1 signifies that the efficiency of the drives is more than 90 percent.
Click here to view Figure 1 in a new window.
No Propeller Drive, Fewer Vibrations
Through the use of SyncroDrive, the propeller, or cardan, shaft is eliminated, so problems such as start and stop marks no longer exist, which has a very positive impact on the whole weaving system. SyncroDrive does not operate with cams, because a cam motion can't be run independently and requires pre-acceleration of the shedding device. The propeller shaft is replaced by an electronic wave (See Figure 2).
Click here to view Figure 2 in a new window.
Eliminating the propeller shaft minimizes vibrations in the Jacquard machine frame. Thus, ground vibrations are reduced and speed variations are less than 1 percent. Next, the harness runs very quietly. With lower vibration, one can assume a longer lifetime of the harness and the modules, as machine vibrations or oscillations can shorten the life of critical components considerably.
Furthermore, a change of the shed closing can be programmed on the display via specialized circuits, and also the pick can be found without reed beat-up. This results in improved weft monitoring without limiting the weaving machine's stop angle. After the stop, an electro-pneumatic, spring-loaded holding brake prevents the independent rotation of the Jacquard drive, even when there is no power.
With SyncroDrive, thanks to the quiet harness, the warp stresses are lowered, and the warp and weft stop values can be reduced (See Table 1).
Table 1: Airjet weaving machine operating at 800 rpm. Comparison of stop value per 100,000 weft insertions for identical weaving machines, set-ups and articles.
Lowered speed fluctuations and, of course, reduced material wear are additional advantages. The SyncroDrive concept, with its EFF1-rated drives, achieves up to 10-percent higher speeds with minimal heat accumulation and the same energy requirement. The soft start and stop are very gentle on the material, which is important for the life cycle of the shedding elements as well as the increased lifetime of the machine, resulting in reduced operating costs. These factors are said to ensure the highest standards in functionality and quality security.
Fewer Warp Breaks
Not to be underestimated in the weaving process is the number of warp breaks: The patented DynamicWarpGuide (DWG), made of spring steel, is a dynamic back rest roller-free arrangement offering synchronous movement with the shed motion, which allows ideal tension compensation when changing the upper and lower shed, even at maximum machine speed - thus preventing the movement of the interlacing points. An optimal fabric spread by the temple is therefore assured.
A Step Into The Future
According to the inventors at Dornier, in a first-class weaving mill, the use of SyncroDrive could lead to a reduction by more than 50 percent of vibrations in the building and its environment. These values are remarkable. The advantages of the SyncroDrive are really only apparent when one is standing in front of the weaving machine in operation. It is amazing to see how the weaving and Jacquard machines operate separately. At Dornier's technical center, the author was able to see for himself the very quiet running of the weaving machine in operation. Without exaggeration, one can say that this new concept will make a big noise in the global weaving community.