New „Posatrefoli“ double-strand laying machine developed
Some years ago, the Italian company Pappadá was contacted by the manager of a precast concrete plant and asked to find a solution for their problems related to laying prestressing wire strands on a 120-m long production line. Stumbling block was the fact that four workers operating the line, now and then, complained about each other that their work was not sufficiently productive and, therefore, the wires often got entangled. But as this really is an extremely demanding task, Pappadá accepted the challenge under the condition that they were allowed to conduct all tests required for adjusting the machine. This was ensured by the client, again under the condition that they would not widen the bore holes of the winding heads and the separators, through which concrete might escape.
What seemed to be an impossible undertaking in the beginning, turned out later to be an undertaking lasting six months for improving the adjustment of the machine alone. The greatest problem was the torsion that the prestressing wire strands released at the moment of passing out of the reel cage, tangling again and again along the tow distance of 130 meters. A test using various wire guides did not lead to the desired result at first. The strand, when it is unwound from the reel, is like a giant spring which had to be kept under control so that it could not injure the operators if appropriate precautions are not taken. A prototype could be provided promptly, but with every test carried out, at first, it did not perform reliably to solve the problem. After a wire length of about 20 meters, either the strand would detach or a huge tangle would form, which made it impossible to carry on.
Two wire strands can be laid in 6 min along 100 m
As chance would have it, the sparking idea came from a development made in fishing sports: there the line does not get tangled up in the reel because the spool revolves around its axis. This concept was adapted to the precast concrete application and a new clamp was developed. The machine worked perfectly right from the first test with the new system. Shortly thereafter, the specialists of Pappadá were awarded a contract to design an even more efficient machine of larger dimensions. This was the beginning of the „Posatrefoli“ double-strand laying machine, allowing two cables to be laid at the same time. The first field test showed that only two operators with a radio remote control each were required to lay strands in about 6 min. In the meantime, comparative tests were carried out with other prototypes built with different principles, but none of the other machines could obtain a similar speed of the strands passing the guide rollers at a speed of 47 m/min without interruption on long production lines.
The sale of the first machine of this type was followed by many more orders. Today, the maximum operating speed is up to 6 min. for two strands of a length of 100 m; theoretically, without any restriction in length.
With the same commitment and inventive spirit, Pappadá produces shuttering magnets of high quality, according to their own information. Apart from the range of standard magnets, the company is able to produce magnets according to individual designs and in almost any shape and size, which come with two-year guarantee.
