Introduction

As the competitiveness of the cable market has increased over the last decade, wire and cable machinery manufacturers are facing a challenge. As ever, quality of product is the truest measure of all. But machinery makers must now produce equipment responsive as well to productivity-driven requirements: reliable units that will improve processing efficiency and reduce downtime. Speed will always be important, not in isolation but as the chief component in productivity, the new benchmark of a successful manufacturing process.

Cortinovis SpA, of Italy, produces efficient and flexible equipment designed to reduce loading time, a critical factor in productivity. The company recently introduced several new units designed to enhance this vital process. A brief description is given of each of these:

• Backtwist-free tubular armouring machine;
• “Conotorsion” laying-up machine;
• Linear-bobbin rigid strander;
• “Monobitorsion” strander for medium voltage cables.

Backtwist-free tubular armouring machine

The backtwist-free tubular armouring process is designed for the application of armouring wires onto delicate cores, e.g. fibre optic cables, and plastic or rubber tubes. The machine itself is composed of tubular sections. The number of pay-off bobbins corresponds to the number of required armouring wires. The central bobbin, which holds the sensitive product core, can be located internally or externally. If internal, it is mounted in a skip section located at the stranding point. If external, it is located at the entrance of the tubular section.

The core enters and exits the tubular strander at a very shallow angle. It is guided by an anti-torsion device which guarantees that the product will not be twisted as it runs along the full path of the tube. The central core is thereby protected from all torsion and de-torsion effects.

Backtwist-free tubular armouring machine with core located internally

Using 630mm (30”) Ø bobbins, the wire armouring backtwist process can run at speeds of up to 500RPM, with linear speeds of 120m/min. A traditional planetary armouring machine will only run at 100RPM. The loading time of the tubular is shorter than for planetary machines, as it is possible to simultaneously load several bobbins.

“Conotorsion” laying-up machine

The Conotorsion is a single-twist machine for laying-up, screening, armouring, and stranding. This Cortinovis unit produces cable in the same manner as a drum twister, and at the higher speed of a conventional single-twist machine. This avoids any centrifugal-forces effect on the take-up bobbins, unavoidable with drum twisters. The machine is based on the single-twist concept of a smooth cable path without deviations.

Dual Conotorsion laying-up line

Laying-up
In this mode, the Conotorsion assembles rigid and flexible insulated conductors, such as control cables and building wire, each with round and sector-shaped constructions.

Screening/armouring
The machine is suitable for screening and armouring, but at twice the output speed of a drum twister. The Conotorsion is especially adapted to the stranding of flexible class 5 cores, known to be a demanding product.

Notable features are:

• Flexible production of the different types of cables with suitable pay-off systems provided;
• Speeds 70 to 100% higher than can be achieved with the corresponding drum twister.

Linear-bobbin rigid strander

The linear bobbin rigid strander is the latest development of Cortinovis SpA. It is designed to provide higher output speeds in the conventional rigid stranding process while preserving all the quality and characteristics of conventional rigid stranders. The linear-bobbin rigid strander is composed of rigid cages, each having all payoff bobbins in a single line - the centre line - and thus allowing rotating speeds considerably higher than previously achievable. The path of the strands, from the back and passing through the linear rigid cage, is attended by the Cortinovis patented flexible articulated joint, which allows for smooth and shallow deviations. Loading of the bobbins is by means of an automatic system utilising lifting platforms from the bottom of the machine. The bobbins are all loaded at the same time, doing away with pits inside the foundations.

This machine is designed for the most stringent power cable production: low, medium, and high-voltage. Rotation speeds of 500RPM with 630mm bobbins Ø are achievable.

“Monobitorsion” strander for medium voltage

The Monobitorsion strander from Cortinovis can produce the same quality output as that from a cage stranding machine. But the Monobitorsion strander offers production speeds comparable to those of a double-twist machine, made possible by the use of a takeup similar to that in a conventional double-twister. The take-up is designed to work in conjunction with a separate, rotating haul-off unit. This combination, together with improvements in the cable guides and deviation devices, allows for stranding of the wires at the single point at which the cable receives its final pitch and size.

Monobitorsion stranding line

The Monobitorsion strander ensures extremely high productivity due to:

• Continuous pay-off from coils, which enables the line to run without interruption for changing the pay-offs;
• Linear speeds of 100m/min with 37 wires compact strands.

Conclusion

Long experience in the field of rotating equipment, and thorough knowledge of the industry, enable Cortinovis to offer exceptional value to each customer. The company’s commitment to research and development, together with its willingness to depart when necessary from conventional thinking, has resulted in design solutions that empower Cortinovis customers to better compete in the international arena. With innovative products like the backtwist-free tubular and the linear-bobbin rigid strander, Cortinovis customers can expect to realise significant increases in productivity and quality even as they reduce their overall manufacturing costs.