Page 83 - Industrial Cutting of Textile Materials

70 Industrial Cutting of Textile Materials

6.3.4 The encoder system

The fully automated spreading process is driven and controlled by an encoder. Using a
special belt with metal denticles fixed to one side of the spreading table (see Fig. 6.10),
the encoder system counts the number of denticles and recalculates them in the dis-
tance (meters or inches) from the start point. This defines the placement coordinates
of the spreader truck on the spreading table at a given moment. Depending on the
encoder system, any marker length with accuracy of ± 1 cm may be programmed and
spread and can be started from any point on the spreading table.
Mechanical and semiautomated machines have a special mechanical stopping de-
vice that stops the machine by friction at the end of a ply. This device is fixed on the
operator's side of the table together with the rails of the machine. When the machine
reaches this point, it is mechanically stopped. Before the start of each new spreading
process, the required length of spread is measured on a table and the stopping device
manually fixed at the end of the spread. Some semiautomatic machines use automatic
sensors to stop the machine.

6.3.5 The end-catcher
The end-catcher fixes the end of a laid material plies and prevents them from moving
during the spreading process (see Fig. 6.11). It is particularly useful when working
with slippery fabrics and with spreading machines that instead of a cradle fabric feed-
ing system have a free bar system. Using not driven free bar system, the fabric is
spread with more tension, and then, the end-catcher keeps the fabric ply to avoid its
pulling back.

Fig. 6.10 The encoder system to define the placement of the spreader truck on the spreading
table.