Page 32 - February-March-2017

32 The TWIN draw frame TD 9T has a compact design, with only one operator platform in the middle
Few machines in a modern spinning
mill are as critical as the roving frame.
Corporate Highlights
Building a solid and reliable roving
frame is not an easy task and yet
again it is absolutely necessary for the
spinner as this machine can feed,
depending on the count being
produced, thousands of spindles at
the spinning frames.
Marzoli, the only European
manufacturer of the full line of
machines for spinning of short staple
fibers with over 150 roving frames
being sold every year worldwide, is
the ideal referent for whoever wants to
choose the best technology. Its FT6E
and FT7E represent a state-of-the-art
solution, yielding the best results for
efficiency, reliability and quality. The
article aims at presenting from a
technical and technological point of
view these machines.
FT6E and FT7E Drive system
leading-edge
roving frame
technology
The FT6E and FT7E are driven by
independent drives for the drafting
system, the flyers, the spindles and
the bobbin rail. Every drive is
coordinated by the central CPU which
ensures perfect synchronization of all
the movements involved in bobbin
formation.
The spindles drive is a group drive
where motion is transmitted through toothed belts. In
traditional machines spindles are moved by one
motor which, through a long shaft, transmits motion
to bevel gears which drive pulleys that drive belts
which ultimately make spindles rotate. A group drive
allows to substantially simplify this transmission
system. The drive comprises several motors, each
one driving a limited number of spindles. Each motor,
through a pulley, drives toothed belts which transmit
motion directly to the spindles. Shafts, gear boxes
and bevel gears are eliminated. Therefore it is
possible to:
- reduce maintenance costs: fewer transmission
components are needed and lubrication is no longer
required;
- reduce noise;
- reduce vibrations: lower mechanical transmission
entails lower wear of transmission components and
therefore lower vibrations. This enables the machine
to work at higher speeds;
- increase transmission efficiency: transmission
system comprises only a pulley and toothed belts: no
shafts, no bevel gears are included. This allows to
reduce energy consumption. short fibers during draft.
Drafting system Marzoli drafting system can also rely on highly
Marzoli roving frames can be equipped with a efficient cleaners for both top rollers and bottom
3-over-3 or 4-over-4 top-of-the-class drafting system.
There are two options for the cylinder diameters: the
standard solution has a diameter of 32mm; however, belts. For the bottom cylinders there are rubber
in case there is a high percentage of short fibers in
the processed material, cylinders with a diameter of
cleaned. This, along with the high quality of each and
every component, entails the perfect control of fibers
during draft and top quality of the roving.
False twist area
As bobbins on modern roving frames are arranged in
two rows, rovings can have different angles at the
delivery of the drafting system and at the entrance of
the flyers’ top. It has been argued that these different
angles can entail differences in the spinning triangle
at draft delivery and different tensions of the rovings
thereby causing an uneven take up of twist and
variations in roving count.
On Marzoli machines all rovings lay parallel to one stems from the amortization of the cost of the head
another: they have the same angle at the delivery of and rear stocks on a higher number of spindles per
the drafting system and at the flyers’ entrance for machine. However, the higher the number of
both the front row and the back row of bobbins. spindles, the smaller the benefit stemming from a
further increase in machine’s length.
Individual sensors ensure that each and every roving
break is properly detected and the machine securely Machines exceeding a certain number of spindles
stopped, even in case of roving overlap around the also entail higher costs for electronics and
cylinder/top roller. On the other hand, if dust passed drafting drive.
in front of the sensors the machine would not stop, it Last but not least a higher number of spindles per
would continue to run. Individual sensors also make
suction not required. This, along with the IE3 motors
machine causes a reduction in efficiency. The FT6E
and an overall design meant to minimize energy (110mm gauge) can reach 224 spindles and
produce bobbins of 16” x 6”. The FT7E (130mm
consumption, allows to save up to 4 Kwh.
gauge) has a spindlage up to 168 spindles and can
produce packages of 16” x 7”. These numbers
represent the limit in terms of number of spindles and
dimensions of bobbins to maintain top efficiency
standards. A higher number of spindles per machine
would not give an additional benefit to the spinner as
the decrease in machine efficiency would not be
counterbalanced by the reduction in the average cost
per spindle.
Roving tension is kept constant within a pre-set
range through sensors that constantly monitor The flyers installed on Marzoli’s roving frames are
roving’s fluctuations between the delivery of the made of ultra-light alloy and are dynamically
drafting system and the flyer’s top and adjust the balanced so that even when working at high speeds,
speed of the spindles accordingly. These sensors vibrations are kept to a minimum. Marzoli’s roving
play an important role in ensuring that there are no frames can reach up to 1,500 rpm mechanically and
false drafts in the roving and that roving breaks are the roving can be wound on standard tubes, with a
27mm can be used to reduce the gauge between kept to a minimum. diameter of 53.5 mm, or on thinner tubes , with a
nipping points. This guarantees a better control of diameter of 48mm, to have a further slight increase in
Winding area bobbin capacity.
It is argued that to increase productivity and lower
investment costs, spindlage and dimension of The creel
bobbins should be increased. This is only partially The creel is equipped with hexagonal aluminum
drafting cylinders. For top rollers there are two true: a higher number of spindles per machine rollers to prevent false drafts, a very important aspect
options: rollers with rubber fins and revolving felt reduces the cost of the investment as the total especially when working with combed slivers. Optic
required number of spindles can be reached with sensors positioned between the rollers ensure that in
scrapers. These solutions guarantee that at every fewer machines. From a unit cost (cost per spindle) case of sliver break the machine is immediately
turn both top rollers and bottom cylinders are always point of view, there is an economic advantage that stopped. Marzoli roving frames can be fed with cans