Study on Flat Bed Knitting Machine

An experiment about the knitting machine of new technology.

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Sessional on TE3203
TE3204


Year-2021
FABRIC MANUFACTURING
ENGINEERING -II
LAB REPORT

Submitted By
Nazmul Hasan Anan
Roll-1721015
Year-3
rd
Term-2
nd

Submitted To
Md. Abdul Alim
Lecturer
KUET

Experiment No-01
Name of the Experiment: Study on Flat Bed Knitting Machine-I)Yarn Path Diagram II)Total
no. of Needles III)Machine Parts IV)Cam Carriage System

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Experiment No-01
Name of the Experiment: Study on Flat Bed Knitting Machine
I) Yarn Path Diagram
II) Total no. of Needles
III) Machine Parts
IV) Cam Carriage System

Introduction:
In Industrial Knitting applications, the terms "Flat" and "Circular" have
very different meanings to those given above. A "Flat" or Vee Bed knitting
machine consists of 2 flat needle beds arranged in an upside-down "V"
formation. These needle beds can be up to 2.5 meters (8 ft. 2 in) wide. A
carriage, also known as a Cambox or Head, moves backwards and forwards
across these needle beds, working the needles to selectively, knit, tuck or
transfer stitches. A flat knitting machine is very flexible, allowing complex
stitch designs, shaped knitting and precise width adjustment. It is, however,
relatively slow when compared to a circular machine. Knitting speed up to
0.5 meters per second (1.6 ft./s) or slower is considered the low speed in
flat knitting which are generally in hand flat machines. The two largest
manufacturers of industrial flat knitting machines are Stoll of Germany, and
Shima Seiki of Japan. The industrial hand flat knitting machine is
considered to be launched by the Isaac Lamb patents.

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Objectives:
 To know about the passage of yarn and fabric of the v-bed knitting
machine.
 To know about the different parts and their functions of the machine.
 To know about the cam arrangement of the machine.
 To know about the different types of knitting cam and their functions.

Apparatus:
I) Machine ( V-Belt)
II) A4 Paper
III) Pencil/Pen
IV) Sharpener
V) Eraser
VI) Ruler
VII) Calculator

Experimental Procedure/Diagram:
Specification:
1. Brand: PROTTI
2. Feeder no: 4
3. Gauge: 8
4. Width: 48 inch

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5. Cam per bed:
 Knit cam- 2 no.s
 Tuck cam- 2 no.s
 Stitch cam- 2no.s
Main Parts of V-Bed Knitting Machine:
1. Yarn package
2. Front needle bed
3. Yarn guide
4. Needle spring
5. Tension spring
6. Fabric
7. Cymbal tension
8. Dead weighting system
9. Yarn take-up
10. Latch needle
11. Fabric comb
12. Yarn carrier
13. Back needle bed
Machine Description:
In the following figure shows a cross section of a simple hand powered and
manipulated V-bed rib flat machine. The trick walls are replaced at the
needle bed verges by fixed, thinner, polished and specially shaped

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knock-over bit edges. In rib gating, a knock-over bit in one bed will be
aligned opposite to a needle trick in the other bed. During knitting process,
the edges of the knock-over bits restrain the sinker loops as they pass
between the needles and thus assist in the knocking over of the old loops
and in the formation of the new loops.

Fig: Diagram of V-bed knitting machine

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The cover plate is a thin metal blade, located in a slot across the top of the
needle bed tricks. It prevents the stems of the needles from pivoting
upwards out of the tricks as a result of the fabric take down tension
drawing the needle hooks downwards whilst allowing the needles to slide
freely in their tricks.
Latch opening brushes are attached to the cam plates of both needle beds to
ensure that the needle latches are fully opened. The supports of the brushes
are adjustable to ensure precise setting of the bristles relative to the needles.
The cam-carriage either slides or runs on ball bearings or wheels, along
guide rails, one of which is fixed over the lower end of each needle bed. It
is propelled either by hand or from a motor driven continuous roller chain
or rubber belt.
Each yarn carrier is attached to a block which slides along a bar, which,
like the carriage guide rails, passes across the full width of the machine.
Two levers are usually provided, one at each end of the needle bed. One is
for racking the back needle bed, to change the gating of the needle beds for
changes of rib set out or rib loop transfer.

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Cam System of the V-bed Hand Flat Machine:
The following figure illustrates the knitting action of a V-bed hand flat
machine and the another figure shows the underside of the cam carriage
and the cams forming the tracks that guide the needle butts through the
knitting system.
The needle butts will enter the traversing cam system from the right during
a left to right carriage traverse and from the left during a right to left
traverse. For each needle bed there are two raising cams (R), two cardigan
cams (C) and two stitch cams (S).
The arrangement as shown in the following figure is referred to as a
knitting system. A single system machine will knit one course of rib in one
traverse whereas a double system machine will knit two courses of rib per
traverse. Sometimes a set of cams in one bed is referred to as a lock.

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Fig: Cam system of the V-bed hand flat machine
A (L) – Raising cam (left)
B (R) – Raising cam (right)
C – Tuck cam (left & right)
D (L) – stitch cam (left)
D (R) – stitch cam (right)
E – Guard cam

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The Knitting Action of the V-bed Hand Flat
Machine:
1. The rest position: The tops of the heads of the needles are level with the
edge of the knock over bits. The butts of the needles assume a straight line
until contacting the raising cams R (R) because the leading stitch cams S
and AS (L) are lifted to an inactive position. The lifting action is an
alternating action that always lowers the trailing stitch cams and raises the
leading stitch cams in each system as the traverse commences. This action
prevents needles from being unnecessarily lowered and strain being placed
on the old loops prior to the startup of the knitting action.

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Fig: Knitting action of the V-bed knitting machine
2. Clearing: The needle butts are lifted as they contact the leading edge of
cams R (R), which raises the needles to ‘tucking in the hook’ height with
the under surface of cams S (L) acting as guard cams. The needles are lifted
to full clearing height as their butts pass over the top of cardigan cams C
(R) and C (L).
3. Yarn feeding: The yarn is fed as the needles descend under the control
of guard cam (G). The required loop length is drawn by latch needle as it
descends the stitch cam S (R).

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4. Knocking over: To produce synchronized knocking over of both needle
beds simultaneously, the stitch cam S (R) in the front system is set lower
than the auxiliary stitch cam AS (R), so that the latter is rendered
ineffective.
Discussion:
In this experiment we learn about the yarn path diagram, total number of
needles, machine parts and cam carriage arrangements of flat bed knitting
machine. The number of needles and cam arrangements are varies from
machine to machine. We learn about the machine parts and their operation
during knitting action. During experiment, we should observed the machine
settings carefully. For further knowledge we can use manual or catalogue
which is provided with the machine.
Conclusion:
Flat bed is a new technology for knitting industry which is introduced
recently. In our lab, the machine which is used is not a machine of
industrial scale. Here we only get a primary idea about flat bed knitting
machine. The primary idea can help us in future application of industrial
scale. By this experiment we may learn how to change the design, how to
operate the v-bed knitting machine and how to changing the position of
cams to produce different types of designs which helps us in our practical
life.