Lap Former
What is Lap Former?
Lap Former Machine of spinning mill is used for lapping cotton and
forming compact lap from drawn sliver by drawing & drafting to
feed the combing machine. In this machine mini lap or comber lap
is produced by using 48-60 slivers.
Figure: Modern Super Lap Former Machine.
Objects/Necessity of lap former:
1. To remove short fibers [There short fibers are called noil].
2. To reduce loss of long fibers.
3. To parallelize the hooked fibers.
4. To make major hooks to take the leading position in the next
machine i.e. comber machine, so that prevents excessive loss.
5. To reduce fiber damage.
6. To reduce strain on comber.
Machines used for Lap preparation:
1. Conventional system –
i. Sliver lap machine.
ii. Ribbon lap machine.
2. Modern System –
I) Super lap former.
Combed yarn I: conventional method (batt
doubling)
a)
Combed yarn II: new method (sliver
doubling)
b)
Figure: Conventional and modern Combing line
Sliver lap machine:
Object of this machine is to produce a narrow lap from a number
of card slivers or draw frame slivers. The machine is made to take
16-20 slivers depending upon the width and weight/yard of the lap
required to be produce.
Figure: Top view of a sliver lap machine.
Figure: Rieter E 2/4A sliver lap machine
Machine Description and material passage: in this machine material i.e.
sliver are passes through the following passages:-
Figure: Material passage diagram of a sliver lap machine (1)
Figure: Material passage diagram of a sliver lap machine (2)
1. 24 slivers from the card are usually fed together and side by side over a table
into a drafting arrangement.
2. A loose form of web is created with a small draft of around 1.5.
3. After pressing and smoothing, this web is rolled up to a lap by calender
rollers.
Technical data:
Raw material: cotton up to 1 5/8 inch staple
Feedstock: up to 80 ktex per drafting arrangement.
Doublings: 24
Draft of the drafting arrangement: 1.31 – 3.03
Lap weight, net: up to 25 kg
Delivery speed: 85-100 m/min
Theoretical production per machine: up to 480 kg/h
Ribbon lap machine:
Figure: Rieter E 4/1 ribbon lap machine
The machine description and material passage of ribbon lap machine is
mentioned below:-
Laps
Gearing
Machine frame
Figure: Elements of a Ribbon lap machine
1. Six laps from the sliver lap machine are simultaneously forwarded
to the ribbon lap machine.
2.These webs pass individually through separate drafting systems
arranged side by side.
3. The 6 webs thus formed run over 6 deflecting plates and then over a
collecting table into a pair of calender rollers.
4. The 6 webs, now overlapping, are pressed together to form a
compact web and rolled up to a lap on the subsequent lap rollers.
5. An inherent feature of this classical system is very low productivity,
i.e. it is therefore unsuitable for modern combing preparation.
1. Lap
Deflecting plates
Collecting table
10
11
Figure: The ribbon lap machine-cross section.
Technical data:
Raw material: cotton up to 1 5/8˝ staple length
Feedstock: up to 80 ktex per drafting arrangement
Doublings: 6
Draft of the drafting arrangement: 3.48 - 8.04
Lap weight, net: up to 20 kg
Delivery speed varies between: 70 and 140 m/min
Theoretical production (per machine): up to 480 kg/h
Modern Preparation System (Sliver doubling system):
The first machines using this system
Figure: Basic design of the former Rieter E 5/3 UNIlap (Lap forming
machine)
Figure: E 32 UNIlap
The idea of creating a comber feeding lap by a single web forming
process directly in front of the comber – with a draw frame passage in
front of this web former, of course – can be traced back to a
development in 1948 by the former Whitin Company, called the super
lap machine. Although all later machines are of different designs they
all are based on this idea. That is why modern high-performance
preparation systems will now be explained on the basis of the Rieter
machines, starting with the first designs.
1. There are 3 creel, so 3 feed plates.
2. 48-60 slivers [16-20 slivers in each creel] are fed at same time.
3. The slivers from the individual creels are passed through 2 over 3
drafting zone.
4. After drafting the webs are led through calendar rollers for further
condensation.
5. The final output product out of calendar roller is lap which is wound
on a spool.
Figure: The lap winding device of the UNIlap machine.
Winding mechanism:
1. Previous mechanism: The calender rollers are followed by two winding
rolls (2) and a lap tube holding device(3) with a lap weighting device; these
have to cooperate to form the lap.The machine stops when a preset lap
length is reached, whereupon an automatic device replaces the full lap
by an empty tube.
2. Modern mechanism/OMEGAlap winding: Since production speeds
using the winding system based on calender rollers have reached their
limit due to the system itself, Rieter developed a new lap winding system.
The new lap winding system makes use of a unique belt tension and
pressure arrangement. The winding belt (Fig.1, 1), with a width similar to
that of the laps, surrounds the lap to form a circumferential pressure
area (omega-shaped) ranging from 180° to 270° from start to full lap.
Fiber guidance and pressure distribution applied by the OMEGA principle
allow constant production (i.e. constant speed during winding of the lap)
at speeds of up to 180 m/min over the entire lap buildup.
Figure 1: OMEGAlap winding process.
Figure: Comparison between two different winding systems of
Rieters combing preparation machines.
Technical data:
Raw material: cotton up to 1 5/8˝ staple length
Feedstock: up to 70 ktex per drafting arrangement
Doublings: up to 28
Draft of the drafting arrangement: 1.36 - 2.2
Lap width: 300 mm
Lap weight, net: up to 25 kg
Delivery speed varies between: 70 and 140 m/min
-with OMEGA system (at constant speeds): up to180 m/min
Theoretical production (per machine): up to 350 kg/h
–with OMEGA system: up to 520 kg/h
