L.C. Institute of Technology Mechanical Engineering Department 1 INTRODUCTION It is therefore a general object of the present invention to provide an improved knuckler for a V net fence weaving machine. It is a particular object of the present invention to provide an improved knuckler for bending over the cut ends of coated v-net fabric. It is another particular object of the present invention to provide an improved apparatus for bending over the cut ends of woven V net fence having a coating there on to perform selvage without hamming the coating. It is another particular object of the cut ends of coated with fabric which knuckling apparatus rotary bending elements and it is still further particular object of the present invention to bend the cut ends of a coated V net material to form knuckled ends having no cuts mars or scrapes thereon. These and other objects of the present invention are achieved by providing apparatus for bending the cut ends of coated wire woven into a v net material. The bending of the cut ends of the coated V net material is performed at sewage stations at both ends of the fabric in a v net fence weaving machine the cut ends of the coated v- net material are bent into a desired position at the selvage stations without cutting marring or scraping the coating there on. 1 V-Net Fence Weaving Machine
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L.C. Institute of Technology Mechanical Engineering Department
1 INTRODUCTION
It is therefore a general object of the present invention to provide an improved
knuckler for a V net fence weaving machine. It is a particular object of the present
invention to provide an improved knuckler for bending over the cut ends of coated v-
net fabric. It is another particular object of the present invention to provide an
improved apparatus for bending over the cut ends of woven V net fence having a
coating there on to perform selvage without hamming the coating. It is another
particular object of the cut ends of coated with fabric which knuckling apparatus
rotary bending elements and it is still further particular object of the present invention
to bend the cut ends of a coated V net material to form knuckled ends having no cuts
mars or scrapes thereon.
These and other objects of the present invention are achieved by providing
apparatus for bending the cut ends of coated wire woven into a v net material. The
bending of the cut ends of the coated V net material is performed at sewage stations at
both ends of the fabric in a v net fence weaving machine the cut ends of the coated
v-net material are bent into a desired position at the selvage stations without cutting
marring or scraping the coating there on.
V net fence is simply a woven steel wire fence coated with zinc to prevent
rust, commonly referred to as galvanized fence there are two kinds of galvanized
chain link GBW or GAW: galvanized before weaving (GBW) or galvanized after
weaving (GAW).The vast majority on the market today is galvanized after weaving.
Color v net fence is sometimes called vnyle or color coated. In this process
steel wire is first coated with zinc and then covered with a vinyl polymer coating that
helps prevent to both the frame work and the fabric of the fence.
Some v net products use an aluminized coating to cover the steel in place of
the zinc that creates a highly reflective finish; regardless of the finish all v net
products offer a durable economical fence system.
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L.C. Institute of Technology Mechanical Engineering Department
2 LITERATURE REVIEW
2.1 THE THINGS TO BE CONSIDERED WHILE SELECTING V-NET
FENCE WEAVING MACHINE:-
Primary Use - If the system is mainly used to accent your landscaping or
define property boundaries, you may be able to use a lighter mesh than if you
were containing pets or protecting property.
Visual Aesthetics - If you desire a fence system that blends into the
environment then you should consider a colour coated system.
Potential Stress - If there is the potential for climbing, or leaning on the fence
you may want to consider a heavier mesh than normal.
Longevity - If the system is to remain for many years, be sure to consider the
finish coating of the mesh. The color coated meshes have a long life
expectancy, holding the appearance from day one throughout.
2.2 APPLICATION: -
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V-net mesh is used as fencing for
sports field, river banks, construction and residence, also animal fencing.
Especially, well suitable for a wide range of application, for example for
enclosing Lawn, Road. Steel diamond mesh has a heavy galvanized coating to
ensure a long life.
2.3 CHARACTERISTICS:-
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The V-net mesh wire construction is:
strong
with wide application
convenient in station
lower price
safe and flexible
does not break
Does not sag or roll up at the bottom.
2.3 V-NET FENCE WEAVING MACHINE:-
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2.3.1 INTRODUCTION OF BELT AND DRIVES
FIG. 1 – BELT DRIVES
The belts or ropes are used to transmit power from one shaft to another by
means of pulleys which rotate at the same speed or at different speeds. The amount
of power transmitted depends upon the followings factors:
1. The velocity of the belt.
2. The tension under which the belt is placed on the pulleys.
3. The arc of contact between the belt and the smaller pulley.
4. The condition under which the belt is used.
It may be noted that
1. The shafts should be properly in line to insure uniform tension across
the belt section.
2. The pulleys should not be too close together, in order that the arc of
contact on the smaller pulley may be as large as possible.
3. The pulleys should not be so far apart as to cause the belt to weigh
heavily on the shaft, thus increasing the friction load on the bearings.
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4. A long belt tends to swing from side, causing the belt to run out of the
pulleys, which in turn develops crooked spots in the belt.
5. The tight side of the belt should be at the bottom, so that whatever sag
is present on the loose side will increase the arc of contact at the
pulleys.
6. In order to obtain good results with flat belts, the maximum distance
between the shafts should not exceed 10 metres and the minimum
should not be less than 3.5 times the diameter of the larger pulley.
2.3.1.1 VELOCITY RATIO OF BELT DRIVE:-
It is the ratio between the velocities of the driver and the follower or driven. It
may be expressed, mathematically, as discussed below:
Let = Diameter of the driver
= Diameter of the follower
= Speed of the driver in r.p.m., and
= Speed of the follower in r.p.m., and
So length of the belt that passes over the driver, in one minute
=
Similarly, length of the belt that passes over the follower, in one minute
=
Since the length of belt that passes over the driver in one minute is
equal to the length of belt that passes over the follower in one minute,
therefore
=
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Velocity ratio, =
When the thickness of the belt (t) is considered, then velocity ratio,
=
2.3.1.2 VELOCITY RATIO OF A COMPOUND BELT DRIVE:-
Sometimes the power is transmitted from one shaft to another, through a number of
pulleys Consider a pulley 2. Since the pulley 2 and 3 are keyed to the same shaft,
therefore the pulley 1 also drives the pulley 3 which, in turn, drives the pulley 4.
Let = Diameter of the pulley 1,
= Speed of the pulley 1 in r.p.m.,
and = Corresponding values for pulleys 2, 3 and4.
We know that velocity ratio of pulley 1 and 2,
= ........ (1)
Similarly, velocity ratio of pulley 3 and 4,
= .......... (2)
Multiplying equations 1 and 2,
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A little consideration will show, that if there are six pulleys, then
=
=
2.3.1.3 LENGTH OF OPEN BELT DRIVE :-
We have already discussed in Art that in an open belt drive, both the
pulleys rotate in the same direction as shown in fig.
FIG. 2- LENGTH OF OPEN BELT DRIVE
Let and = Radii of the larger and smaller pulleys,
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X = Distance between the centres of two pulleys
(I.e. ) and
L = Total length of the belt.
Let the belt leaves the larger pulley at E and G and the smaller pulley
at F and H as shown in fig . Through , draw M parallel to FE.
From the geometry of the fig. We find that will be perpendicular to
Let the angle = radius.
We know that the length of the belt,
L = Arc GJE + EF + Arc FKH + HG = 2( Arc JE + EF + Arc FK ) ............(1)
from the geometry of the fig, we find that
= = =
Since is very small, therefore putting
= = ................ (2)
Arc JE = ............... (3)
Similarly Arc FK = ................ (4)
And EF=
=
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=x
Expanding this equation by binomial theorem,
EF=x [1-
=x- .................... (5)
Substituting the value of arc JE from equ. (3), arc FK from equ. (4) and EF fromEquation (5) in equation (1), we get
L= .... (In terms of pulley
radii)
L= .... (In terms of
pulley dia.)
2.3.1.4 ADVANTAGES AND DISADVANTAGES OF V-BELT DRIVE OVER FLAT BEET DRIVE:-
Following are advantages and disadvantages of the V-belt drive over flat belt
drive.
ADVANTAGES :
1. The V-belt drive gives compactness due to the small distance between the
centre of pulleys.
2. The drive is positive, because the slip between the belt and the pulley groove
is negligible.
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3. Since the V-belt are made endless and there is no joint trouble, therefore the
drive is smooth.
4. It provides longer life, 3to 5 years.
5. It can be easily installed and removed.
6. The operation of the belt and pulley is quiet.
7. The belts have the ability to cushion the shock when machines are started.
8. The high velocity ratio (maximum 10) may be obtained.
9. The wedging action of the belt in the groove gives high value of limiting ratio
of tensions. Therefore the power transmitted by V-belts is more than flat belts
for the same coefficient of friction, arc of contact and allowable tension in the
belts.
10. The V-belt may be operated in either direction with tight side of the belt at
the top or bottom. The centre line may be horizontal, vertical or inclined.
DISADVANTAGES:-
1. The V-belt drive cannot be used with large centre distances.
2. The V-belts are not so durable as flat belts.
3. The construction of pulley for V-belts is more complicated than pulleys for
flat belts.
4. Since the V-belts are subjected to certain amount of creep, therefore these are
not suitable for constant speed application such as synchronous machines, and
timing devices.
5. The belt life is greatly influenced with temperature changes, improper belt
tension and mismatching of the length.
6. The centrifugal tension prevents the use of V-belts at speeds below 5 m/s and
above 50 m/s
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2.3.2 INTRODUCTIN OF BELTS:-
2.3.2.1TYPES OF BELTS:-
FIG 3-FLAT BELT
Though there are many types of belts used these days, yet the following are important from the subject point of view:
1. Flat belt 2. V-belt 3. Circular belt or rope
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2.3.2.2 STANDARD PITCH LENGTH OF V-BELTS:-
According to IS: 2494 -1974, the V-belts designated by its type and nominal
inside length. For example, a V-belt of type A and inside length 914 mm is designed
as A914-IS: 2494.
The standard inside lengths of V-belts in mm is as follows: