The trimming group (fig. B) which is the most important part of the trimming machine, consists of:
a rotating trimming cylinder (figs. A and B, 8 and fig. 8, detail), called male, which depending on
of its diameter, it can accommodate from 16 to 32 helical blades of tempered steel placed on it
it to screw;
an adjustable blade, called a knife (fig. B, 9 and fig. 9, detail), as long as the cylinder and locked
on the special support (fig. B, 10).
The helical blades of the trimming cylinder, in contact with the underlying fixed blade (knife) create
a contrasting cut point of the hair. When the trimming cylinder has completed its turn, the blade
with a helix attached to it, he cut the hair from one selvedge to the other. Helical blades can be
wound on the cylinder from right to left or vice versa. The direction of the propellers on multi-cylinder trimmers
it is alternated to avoid deviations of the piece and stabilize it in the center.
The fluff produced by the topping is removed by a vacuum cleaner (fig. A, 12).
A pneumatic lifter (fig. A, 11) intervenes at the passage of the seam at the end of the piece.
In addition to the velvet machine and topping groups, there are:
hair-coated brushes (fig. A, 13); particularly important is the one placed before the group
trimmer which, acting on the reverse side, removes any threads or fibers from the surface of the fabric;
feelers, which operate the lifting of the cylinders when the seams pass wide;
a thick felt soaked in a special oil that rests on the trimming cylinder, which keeps the helical threads and the fixed blade efficient for longer;
a series of dragging cylinders, which carry the pieces to the folding machine.
The trimmer configurations can include: 1) single machine; 2) multiple machines online; 3)
machines arranged on a chain of different processes (for example raising and topping).