STENTER DRYING WITH MULTIPLE HORIZONTAL LEVELS
Drying of fabrics is normally required after wet processing (washing, bleaching, dyeing, printing, impregnation with chemical solutions, sizing etc.). In the named machine stenter or stenter is carried out by investing the piece with a flow of hot air.
The flat ramose are less effective and are used on light and knitted fabrics, those with multiple paths horizontal, with top entry and bottom exit on the same side, are preferred for fabrics of wool and drapery in general.
Steam, diathermic oil and combustion can be used for heating the air
direct gas. The last two systems are indispensable in the presence of a section for heat fixing in which very high temperatures must be reached.
The fabric circulates on the various floors of the machine (four or more, depending on the capacity) via two
continuous chains (see figure A, point 1), on the links of which metal plates with
stainless steel pins on which selvedges held flat by two or three cylinders are pinned
unwinds, controlled independently. Two arms are placed outside the machine (fig.
A, 2) - within which the continuous chains slide - equipped with electronic probes to ensure correct
positioning of pins and selvedges, which, once pinned, support the effort of enlargement of the fabric.
The fabric passes between two overlapping pulleys on each side (fig. A, 3) which push it allowing to
supercharge it with respect to the path of the chains to obtain, if necessary, a greater return to the
sense of length. A brush (fig. A, 4) forces the fabric to penetrate with its own weight
deeply from the pins, so that ventilation does not cause detachment and consequent
automatic machine stop. A velvety brush is placed before the selvedgers
(fig. A, 5), which smoothes and parallels the fibers, almost always preceded by a weft straightening device
(fig. A, 6) which guarantees straight wire weaves and well square designs.
The fabric descends inside the drying chamber from above and comes out at the bottom, dry and cooled
by a perforated cylinder (fig. A, 7) equipped with aspirator, ready to be folded or rolled
according to the requirements.
Finned radiators placed on the walls in each of the two half vertical sections (fig. A, 8) generate the
necessary heat and two fans and some blowers (fig. A, 9) convey the air onto the piece, into the
first half section (fig. A, a), from bottom to top and in the second half section (fig. A, b), from top
downwards, to obtain perfect drying over the entire height of the fabric.
The hot air, saturated with the humidity of the fabric, is released through special suction ducts (fig.
A, 10) equipped with adjustable valves, while thermal insulation panels on the surface of the machine avoid heat loss.
At the bottom of the sliding guides, the two gears driving the chains are connected in parallel by
a shaft lined with a cylinder with three periscopic elements (fig. A, 11), which varies the width of the field of work.
The machine can have automatic systems that set the optimal speed, based on the humidity of the patches.
Some types of fabrics must be wet or soaked with certain products
before being dried. For this reason, a squeezer (scarf) is mounted at the entrance
of the stenter.
STENTER FLAT DRYING AND THERMOFIXING
The piece makes a single horizontal passage in the machine, exiting the opposite side
at the entrance, where a camera transmits its image on video to the operator.
The piece, folded or rolled, passes in succession through:
a tensioner (see figure B, 1);
a brush (fig. B, 2) for the elimination of any fluff deposited on the fabric;
a fabric centering device (fig. B, 3);
a bleaching scarf (fig. B, 4) and a weft straightening device (fig. B, 5), which guarantee the
regular presentation of the fabric for drying.
Spreading cylinders (fig. B, 8) placed along the path make it go on in a regular way
above the feed cylinder (fig. B, 9)
through the selvedge unrollers (fig. B, 10) and a fabric feeler (fig. B, 11)
above the charge wheels (fig. B, 12).
Then the piece is stitched on the chain
cross the steamer (fig. B, 14), composed of a carpet (fig. B, 15) and an electrical panel
(fig. B, 13) and then,
a screw widens / tightens (fig. B, 16) adjusts the height, before
drying sections, the number of which may vary according to the processing and production needs,
two fans (fig. B, 18) one on the right and one on the left of the section,
two exhaust pipes (fig. B, 17) placed above the section,
two series of blowers (fig. B, 19),
a chain guide (fig. B, 20) to adjust the height of the piece,
a fume exhaust (fig. B, 21), in the last section of the ramosa, serves for the whole machine.
After drying, the piece passes into a cooling area (fig. B, 22), where a cylinder
dancer (fig. B, 24) holds it in the right tension to pack it in a large roll (fig. B,
23) or to deposit it in layers (fig. B, 25) on the appropriate pallet.
The assistant is located on a platform (fig. B, 6), in front of the control console (fig. B, 7) and sees the beginning
steam treatment - recommended for knitted fabrics - and drying.
On open knitted fabric it is necessary to glue the selvedges (i.e. the ends
cut), to avoid rolling it up. Two side trays, equipped with impregnation brushes, containing
the adhesive allows this operation before entering the drying chamber.
The flat ramosa is used for drying light cotton, polyester and blended fabrics
synthetic fibers, including stretch fabrics.
The heat setting operation, which is carried out both to make subsequent processing easier
which, to meet the needs of the packer, gives dimensional stability to the fabric, compatibly
the behavior of the fibers at high temperatures. On mixed polyester-wool fabrics it improves
also the elasticity, the anti-crease effect and the pilling resistance of the polyester part.
To carry out the heat setting it is necessary to reach temperatures of 170/190 ° C and a permanence
of the fabric in the chamber for 20/25 seconds. Since the flat ramosa guarantees
uniformity of heat over the entire surface of the piece, can be used for the heat setting of
In a multi-module machine, heat setting can be carried out using:
the first modules for drying
and the last ones for thermofixing.
The machine speed must be set so that the residence time is 20/25
dry piece seconds, depending on the type of machine.
FREE DRYING FOR KNITWEAR
This operation, carried out mainly on tubular knitted or previously opened fabrics,
it guarantees a good return because it occurs without any tension on the fabric both in length and in length
in width. The machine also allows the drying of traditional fabrics.
The fabric to be dried, in rolls or in layers, is placed in the center of the machine entrance and passes:
through an expanding device (see figure A, point 1)
between two supercharging introducer cylinders (fig. A, 2) which arrange the pieces
on the conveyor belt (fig. A, 3); here a probe controls the guide cylinder which holds the
conveyor belt in central position;
a pre-drying chamber (fig. A, 4) receives the tape and dries the fabric through blowers (fig.
A, 5), without subjecting it to the vibrations present in the following ones
vibration drying chambers (fig. A, 6), here special dryers are added
pneumatic blowers (fig. A, 7) with controlled impulses, which shake the fabric with strong flows of
alternating air from below and above.
The pneumatic blowers placed under the belt are staggered with respect to the upper ones, belt and fabric they receive
so continuously alternating downward and upward thrusts, which almost force them to
At the end of the journey, a cooler (fig. A, 10) welcomes the fabric which is then deposited
on a conveyor belt (fig. A, 11) which ends with a stapler (fig. A, 12) of the pieces.
The heat generators (fig. A, 8) and the relative fans are installed alternately above the machine
(fig. A, 9). A exhaust fan expels moisture and provides adequate air exchange.
Ask info for Stenter process
Please write your email address