WCN Spring 2011

Automatic traverse control

D631 with automatic traverse system

Valley

This does not look good and could be better

- Detection of flange and change-over - Spooling without hills and valleys

This picture clearly shows what a laying pattern should not look like. On the left you can see a hill, on the right there is a valley.

- Target: pay-off speed up to 1,500rpm - Traverse drive with stepper motor - Electronic device NBAT2 - 2 laser sensors at the traverse pulley

The Niehoff solution:

production of strands do not differ considerably. If you want to be better than the standard and produce high-quality strands, the mentioned details help you and result in quality improvements of the finished products and high production safety with fewer mistakes as well as higher customer acceptance. A first-class annealer should produce wire elongation values much above DIN standard. The target should be to maintain them as far as possible through the whole process up to the final cable product by following all recommendations mentioned before. For the sale of cable its conductance is more often the determining/decisive factor than its cross section. This means the less the loss of elongation produced in the production line, the lower is the resistance and the higher the electric conductance of the cable. This means that a bad conductance requires more copper in the cable; good conductance on the contrary needs less copper. Back to the loss of elongation

The consequences of a poorly wound spool appear in the downstream process and are the main reason for wire breaks and slow speeds there. Niehoff has also developed an automatic traverse control for bunching machines based on the optical control of the flanges. In the stranding process, wires are often spooled on plastic spools with high winding tension. Here it is very important to determine the exact switchover point to avoid the flanges to flare out. Two laser sensors control the flange position, and the traverse unit which is driven by a stepping motor moves towards this position. This ‘Niehoff Bunching Automatic Traverse’ system (NBAT) was introduced to the market a few years ago and many cable makers have realised its benefits. Spools wound with the help of this system enable a trouble-free paying-off before the extrusion lines at line speeds of up to 1,500m/min. tension throughout the spool filling is another important point in wire stranding. Niehoff has equipped its bunching machines with load cells and dancer pulleys to control, using a closed loop control system, the set winding tension throughout the spool filling. The constant winding

Automatic traverse width control in the spoolers

Automatic traverse control for spooler

The most time-consuming activity of the operator besides wire feeding is to control and to adjust the correct wire laying. It is absolutely necessary for a safe and smooth paying-off of the wires in the downstream process step to watch the wire lay very closely. Niehoff has developed and patented an automatic system which controls and corrects the traverse using a special software program. The constant speed control at the traversing unit recognises the formation of hills or valleys due to the aligned change in wire speed. A higher speed indicates the formation of a hill – lower speeds mean the formation of valleys. Special software detects and processes these points, and corrects them in the next traverse movements.

Conclusion

As far as the basic machines are concerned, the processes for the

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WCN Issue N° 44 www.iwma.org