Post on 08-Nov-2014
description
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AUTOMATIC SPRING ROLLING MACHINE
SYNOPSIS
In spring working industry a wide range of power and hand
operated machines are used. As the industry is a large and growing
industry different type of machines are used for different operations.
Our project the spring rolling machine is very simple in operation by
using spur gear arrangement which is coupled with motor. This
machine produces round spring of different diameters and length. This
machine can be used in various fields. This machine consist of two spur
gear which is coupled with a motor and connecting the spur gear shaft
with rolling main shaft. This machine is simple in construction and
working principle.
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INTRODUCTION
Spring rolling industry is a large and growing industry. There are
many special purposes machines used in this industry to-day. The
proper selection of the machines depends upon the type of the work
under-taken by the particular industry. There are many examples of
spring, which can be seen in our every day lives. The metals generally
used for spring rolling work include iron, copper, tin, aluminium,
stainless and brass.
Our project the “SPRING ROLLING MACHINE” finds huge
application in all spring rolling industry. Rolling is the process of
bending metal wire to a curved form. The article in the shape of round
is made by spring roller shaft. Rolling operation can be done on hand
or power operated rolling machines. In forming round spring shapes a
gradual curve is to be put in the metal rather than sharp bends. The
gap between the springs can be regulated by proper arrangement.
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The lock nut is used to fixing the spring wire to the rolling shaft.
The spring wire is supplied by a tare is called spring wire tare. This tare
is fixed to the stand by two end bearings. The tare is rotated freely
during the time of spring rolling operation. The single phase induction
motor is coupled with the spur gear arrangement by pulleys. The motor
is rotated by switch on the power supply of single phase. The spur gear
is rotated due to the rotation of motor. The spur gear is coupled with
the main shaft by bearing.
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WORKING PRINCIPLE
The single phase supply is given to the induction motor, it will
run. The motor pulley is coupled to the spur gear pulley with the help
of belt. The spur gear arrangement is run according to the speed of the
motor. Before switch on the induction motor, the spring wire is locked
to the lock nut in the spring rolling shaft. The spring wire is supply by a
spring wire tare. The tare is fixed to the frame stand by two end
bearings, so that it will run freely according to the speed of the spring
rolling shaft.
The spring rolling shaft is rotated when the single phase induction
motor switched ON. The spring wire is rolling in the rolling shaft due to
the rotation of the spring rolling shaft. The length of the rolling spring
is decided by the operator. The required length of the spring is rolled;
the single phase induction motor is switched OFF. The spring is cut by
the cutter, the next above procedure continue once again for the next
spring operation.
ADVANTAGES
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Easy in Construction and Working Principle
Man power requirement is less
High production
Length of the spring is varied
Production cost is reduced
Low Cost
Maintenance cost is very low.
Unit is compact so less space is required
Time consumption is less
Less effort & productive
Easy to install at any were
Skilled workers are not required
Convenient for mass production
Less in weight
APPLICATIONS
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Small Scale industries such as wire rolling, belt rolling
etc.
Wire rolling industries
All spring rolling industries
DISADVANTAGES
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This machine is applicable for particular diameter of
the spring
This machine is used to produce soft spring wire only
The Purpose
Coil springs are a spiral thick metal wire that is made of steel. Used in a car’s
suspension system to hold the weight, keep the ride height and control the
ride of the vehicle.
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Why replace coil springs?
There are many factors as to why coil springs are replaced. Some are by
choice and other because they need replacing. Below are some of the
reasons coil springs are replaced.
Sagging
Coil springs support a car’s body; over time coil springs will weaken and sag
causing the ride height to lower. As the coil springs sag, on side of the car
may be lower than the other and case the car to tilt.
Tyre wear
While stabilising the car’s body, coil springs and shocks keep a car’s tyres
firmly on the ground, keeping the axles at the correct angles. Warn coil
springs and shocks can misalign tyres and/or track abnormally, causing early
tyre wear.
Noise
When a car is driven over large bumps, pot holes and/or around tight corners
if a noise occurs, this often is a sign of worn coil springs and/or shock
absorbers.
Bounce
When driving if you car is bouncing or feels like you’re in a boat, you need to
replace your coil springs and/or shock absorbers.
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Swaying
Coil springs and shocks work together to keep a car centered and stabilized
while going around tight corner. Worn coil springs and shock absorbers loose
their stabilising capabilities and cause a car to sway excessively.
Height
By replacing the coil springs you can choose the ride height. There is
typically three options for most cars these being:
* Standard height
Restore the car to its formal ride height
* Lowered height
There are options of 20mm to 60mm lower than original height. When
lowering a car remembers the car will be closer to the road, tyres and
suspension bump stops. Depending on how lowered you choose, you may
also need to replace your shock absorbers.
* Raised height
Options are 20mm to 50mm raised above original height of the car. Why
raise the ride height?
For many reasons for example towing, LPG tank, 4WDing, load carrying and
for increased ground clearance.
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A
SPRING is an elastic
object used to store mechanical energy. Springs are usually made out of
spring steel. Small springs can be wound from pre-hardened stock, while
larger ones are made from annealed steel and hardened after fabrication.
Some non-ferrous metals are also used including phosphor bronze and
titanium for parts requiring corrosion resistance and beryllium copper for
springs carrying electrical current (because of its low electrical resistance).
When a spring is compressed or stretched, the force it exerts is proportional
to its change in length. The rate or spring constant of a spring is the change
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in the force it exerts, divided by the change in deflection of the spring. That
is, it is the gradient of the force versus deflection curve. An extension or
compression spring has units of force divided by distance, for example lbf/in
or N/m. Torsion springs have units of force multiplied by distance divided by
angle, such as N·m/rad or ft·lbf/degree. The inverse of spring rate is
compliance, that is: if a spring has a rate of 10 N/mm, it has a compliance of
0.1 mm/N. The stiffness (or rate) of springs in parallel is additive, as is the
compliance of springs in series.
Depending on the design and required operating environment, any material
can be used to construct a spring, so long as the material has the required
combination of rigidity and elasticity: technically, a wooden bow is a form of
spring.
Springs can be classified depending on how the load force is applied to them:
Tension/Extension spring – the spring is designed to operate with a
tension load, so the spring stretches as the load is applied to it.
Compression spring – is designed to operate with a compression load,
so the spring gets shorter as the load is applied to it.
Torsion spring – unlike the above types in which the load is an axial
force, the load applied to a torsion spring is a torque or twisting force,
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and the end of the spring rotates through an angle as the load is
applied.
Constant spring - supported load will remain the same throughout
deflection cycle[5]
Variable spring - resistance of the coil to load varies during
compression[6]
They can also be classified based on their shape:
Coil spring – this type is made of a coil or helix of wire
Flat spring – this type is made of a flat or conical shaped piece of
metal.
Machined spring - this type of spring is manufactured by machining bar
stock with a lathe and/or milling operation rather than coiling wire.
Since it is machined, the spring may incorporate features in addition to
the elastic element. Machined springs can be made in the typical load
cases of compression/extension, torsion, etc.
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The most common TYPES OF SPRING are:
Cantilever spring – a spring which is fixed only at one end.
Coil spring or helical spring – a spring (made by winding a wire around
a cylinder) and the conical spring – these are types of torsion spring,
because the wire itself is twisted when the spring is compressed or
stretched. These are in turn of two types:
o Compression springs are designed to become shorter when
loaded. Their turns (loops) are not touching in the unloaded
position, and they need no attachment points.
A volute spring is a compression spring in the form of a
cone, designed so that under compression the coils are not
forced against each other, thus permitting longer travel.
o Tension or extension springs are designed to become longer
under load. Their turns (loops) are normally touching in the
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unloaded position, and they have a hook, eye or some other
means of attachment at each end.
Hairspring or balance spring – a delicate spiral torsion spring used in
watches, galvanometers, and places where electricity must be carried
to partially rotating devices such as steering wheels without hindering
the rotation.
Leaf spring – a flat spring used in vehicle suspensions, electrical
switches, and bows.
V-spring – used in antique firearm mechanisms such as the wheellock,
flintlock and percussion cap locks.
Other types include:
Belleville washer or Belleville spring – a disc shaped spring commonly
used to apply tension to a bolt (and also in the initiation mechanism of
pressure-activated landmines).
Constant-force spring — a tightly rolled ribbon that exerts a nearly
constant force as it is unrolled.
Gas spring – a volume of gas which is compressed.
Ideal Spring – the notional spring used in physics: it has no weight,
mass, or damping losses.
Mainspring – a spiral ribbon shaped spring used as a power source in
watches, clocks, music boxes, windup toys, and mechanically powered
flashlights
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Negator spring – a thin metal band slightly concave in cross-section.
When coiled it adopts a flat cross-section but when unrolled it returns
to its former curve, thus producing a constant force throughout the
displacement and negating any tendency to re-wind. The commonest
application is the retracting steel tape rule.[7]
Progressive rate coil springs – A coil spring with a variable rate, usually
achieved by having unequal pitch so that as the spring is compressed
one or more coils rests against its neighbour.
Rubber band – a tension spring where energy is stored by stretching
the material.
Spring washer – used to apply a constant tensile force along the axis of
a fastener.
Torsion spring – any spring designed to be twisted rather than
compressed or extended. Used in torsion bar vehicle suspension
systems.
Wave spring – a thin spring-washer into which waves have been
pressed.[8]
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Contents
[hide]
1 History
2 Types
3 Physics
o 3.1 Hooke's law
o 3.2 Simple harmonic motion
4 Theory
5 Zero-length springs
6 Uses
7 References
8 Further reading
9 External links
[edit] History
Simple non-coiled springs were used throughout human history e.g., the bow
(and arrow). In the Bronze Age more sophisticated spring devices were used,
as shown by the spread of tweezers in many cultures. Ctesibius of Alexandria
developed a method for making bronze with spring-like characteristics by
producing an alloy of bronze with an increased proportion of tin, and then
hardening it by hammering after it is cast.
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Coiled springs appeared early in the 15th century,[1] in door locks.[2] The first
spring powered-clocks appeared in that century[2][3][4] and evolved into the
first large watches by the 16th century.
In 1676 British physicist Robert Hooke discovered the principle behind
springs' action, that the force it exerts is proportional to its extension, now
called Hooke's law.
[edit] Types
A spiral torsion spring, or hairspring, in an alarm clock.
A volute spring. Under compression the coils slide over each other, so
affording longer travel.
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Vertical volute springs of Stuart tank
Tension springs in a folded line reverberation device.
A torsion bar twisted under load
Leaf spring on a truck
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Springs can be classified depending on how the load force is applied to them:
Tension/Extension spring – the spring is designed to operate with a
tension load, so the spring stretches as the load is applied to it.
Compression spring – is designed to operate with a compression load,
so the spring gets shorter as the load is applied to it.
Torsion spring – unlike the above types in which the load is an axial
force, the load applied to a torsion spring is a torque or twisting force,
and the end of the spring rotates through an angle as the load is
applied.
Constant spring - supported load will remain the same throughout
deflection cycle[5]
Variable spring - resistance of the coil to load varies during
compression[6]
They can also be classified based on their shape:
Coil spring – this type is made of a coil or helix of wire
Flat spring – this type is made of a flat or conical shaped piece of
metal.
Machined spring - this type of spring is manufactured by machining bar
stock with a lathe and/or milling operation rather than coiling wire.
Since it is machined, the spring may incorporate features in addition to
the elastic element. Machined springs can be made in the typical load
cases of compression/extension, torsion, etc.
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The most common types of spring are:
Cantilever spring – a spring which is fixed only at one end.
Coil spring or helical spring – a spring (made by winding a wire around
a cylinder) and the conical spring – these are types of torsion spring,
because the wire itself is twisted when the spring is compressed or
stretched. These are in turn of two types:
o Compression springs are designed to become shorter when
loaded. Their turns (loops) are not touching in the unloaded
position, and they need no attachment points.
A volute spring is a compression spring in the form of a
cone, designed so that under compression the coils are not
forced against each other, thus permitting longer travel.
o Tension or extension springs are designed to become longer
under load. Their turns (loops) are normally touching in the
unloaded position, and they have a hook, eye or some other
means of attachment at each end.
Hairspring or balance spring – a delicate spiral torsion spring used in
watches, galvanometers, and places where electricity must be carried
to partially rotating devices such as steering wheels without hindering
the rotation.
Leaf spring – a flat spring used in vehicle suspensions, electrical
switches, and bows.
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V-spring – used in antique firearm mechanisms such as the wheellock,
flintlock and percussion cap locks.
Other types include:
Belleville washer or Belleville spring – a disc shaped spring commonly
used to apply tension to a bolt (and also in the initiation mechanism of
pressure-activated landmines).
Constant-force spring — a tightly rolled ribbon that exerts a nearly
constant force as it is unrolled.
Gas spring – a volume of gas which is compressed.
Ideal Spring – the notional spring used in physics: it has no weight,
mass, or damping losses.
Mainspring – a spiral ribbon shaped spring used as a power source in
watches, clocks, music boxes, windup toys, and mechanically powered
flashlights
Negator spring – a thin metal band slightly concave in cross-section.
When coiled it adopts a flat cross-section but when unrolled it returns
to its former curve, thus producing a constant force throughout the
displacement and negating any tendency to re-wind. The commonest
application is the retracting steel tape rule.[7]
Progressive rate coil springs – A coil spring with a variable rate, usually
achieved by having unequal pitch so that as the spring is compressed
one or more coils rests against its neighbour.
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Rubber band – a tension spring where energy is stored by stretching
the material.
Spring washer – used to apply a constant tensile force along the axis of
a fastener.
Torsion spring – any spring designed to be twisted rather than
compressed or extended. Used in torsion bar vehicle suspension
systems.
Wave spring – a thin spring-washer into which waves have been
pressed.[8]
[edit] Physics
[edit] Hooke's law
Main article: Hooke's law
As long as they are not stretched or compressed beyond their elastic limit,
most springs obey Hooke's law, which states that the force with which the
spring pushes back is linearly proportional to the distance from its
equilibrium length:
where
x is the displacement vector – the distance and direction the spring is
deformed from its equilibrium length.
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F is the resulting force vector – the magnitude and direction of the
restoring force the spring exerts
k is the rate, spring constant or force constant of the spring, a
constant that depends on the spring's material and construction.
Coil springs and other common springs typically obey Hooke's law. There are
useful springs that don't: springs based on beam bending can for example
produce forces that vary nonlinearly with displacement.
[edit] Simple harmonic motion
Main article: Harmonic oscillator
Since force is equal to mass, m, times acceleration, a, the force equation for
a spring obeying Hooke's law looks like:
The displacement, x, as a function of time. The amount of time that passes
between peaks is called the period.
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The mass of the spring is assumed small in comparison to the mass of the
attached mass and is ignored. Since acceleration is simply the second
derivative of x with respect to time,
This is a second order linear differential equation for the displacement as a
function of time. Rearranging:
the solution of which is the sum of a sine and cosine:
and are arbitrary constants that may be found by considering the initial
displacement and velocity of the mass. The graph of this function with
(zero initial position with some positive initial velocity) is displayed in the
image on the right.
[edit] Theory
In classical physics, a spring can be seen as a device that stores potential
energy, specifically elastic potential energy, by straining the bonds between
the atoms of an elastic material.
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Hooke's law of elasticity states that the extension of an elastic rod (its
distended length minus its relaxed length) is linearly proportional to its
tension, the force used to stretch it. Similarly, the contraction (negative
extension) is proportional to the compression (negative tension).
This law actually holds only approximately, and only when the deformation
(extension or contraction) is small compared to the rod's overall length. For
deformations beyond the elastic limit, atomic bonds get broken or
rearranged, and a spring may snap, buckle, or permanently deform. Many
materials have no clearly defined elastic limit, and Hooke's law can not be
meaningfully applied to these materials. Moreover, for the superelastic
materials, the linear relationship between force and displacement is
appropriate only in the low-strain region.
Hooke's law is a mathematical consequence of the fact that the potential
energy of the rod is a minimum when it has its relaxed length. Any smooth
function of one variable approximates a quadratic function when examined
near enough to its minimum point as a result of the Taylor series. Therefore,
the force—which is the derivative of energy with respect to displacement—
will approximate a linear function.
Force of fully compressed spring
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where
E – Young's modulus
d – spring wire diameter
L – free length of spring
n – number of active windings
– Poisson ratio
D – spring outer diameter
[edit] Zero-length springs
"Zero-length spring" is a term for a specially designed coil spring that would
exert zero force if it had zero length. That is, in a line graph of the spring's
force versus its length, the line passes through the origin. Obviously a coil
spring cannot contract to zero length because at some point the coils will
touch each other and the spring will not be able to shorten any more. Zero
length springs are made by manufacturing a coil spring with built-in tension,
so if it could contract further, the equilibrium point of the spring, the point at
which its restoring force is zero, occurs at a length of zero. In practice, zero
length springs are made by combining a "negative length" spring, made with
even more tension so its equilibrium point would be at a "negative" length,
with a piece of inelastic material of the proper length so the zero force point
would occur at zero length.
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A zero length spring can be attached to a mass on a hinged boom in such a
way that the force on the mass is almost exactly balanced by the vertical
component of the force from the spring, whatever the position of the boom.
This creates a horizontal "pendulum" with very long oscillation period. Long-
period pendulums enable seismometers to sense the slowest waves from
earthquakes. The LaCoste suspension with zero-length springs is also used in
gravimeters because it is very sensitive to changes in gravity. Springs for
closing doors are often made to have roughly zero length so that they will
exert force even when the door is almost closed, so it will close firmly.
Hooke's Law
Springs are fundamental mechanical components which form the basis of
many mechanical systems. A spring can be defined to be an elastic member
which exerts a resisting force when its shape is changed. Most springs are
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assumed linear and obey the Hooke's Law,
where F is the resisting force, D is the displacement, and the k is the spring
constant.
For a non-linear spring, the resisting force is not linearly proportional to its
displacement. Non-linear springs are not covered in depth here.
Basic Spring Types
Springs are of several types, the most plentiful of which are shown as
follows,
Circular cross section springs are shown. If space is limited, such as with
automotive valve springs, square cross section springs can be considered. If
space is extremely limited and the load is high, Belleville washer springs can
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be considered. These springs are illustrated below,
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Leaf springs, which are illustrated below in a typical wheeled-vehicle
application, can be designed to have progressive spring rates. This "non-
linear spring constant" is useful for vehicles which must operate with widely
varying loads, such as trucks.
History of Springs
Like most other fundamental mechanisms, metal springs have existed since
the Bronze Age. Even before metals, wood was used as a flexible structural
member in archery bows and military catapults. Precision springs first
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became a necessity during the Renaissance with the advent of accurate
timepieces. The fourteenth century saw the development of precise clocks
which revolutionized celestial navigation. World exploration and conquest by
the European colonial powers continued to provide an impetus to the
clockmakers' science and art. Firearms were another area that pushed spring
development.
The eighteenth century dawn of the industrial revolution raised the need for
large, accurate, and inexpensive springs. Whereas clockmakers' springs were
often hand-made, now springs needed to be mass-produced from music wire
and the like. Manufacturing methodologies were developed so that today
springs are ubiquitous. Computer-controlled wire and sheet metal bending
machines now allow custom springs to be tooled within weeks, although the
throughput is not as high as that for dedicated machinery.
Risk Factors
Compression spring bucking refers to when the spring deforms in a non-axial
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direction, as shown here,
Buckling is a very dangerous condition as the spring can no longer provide
the intended force. Once buckling starts, the off-axis deformation typically
continues rapidly until the spring fails. As a result, it is important to design
compression springs such that their likeliness to buckle is minimized.
Buckling of compression springs is similar to buckling for vertical structural
columns. When the free height of the spring (Lfree) is more than 4~5 times
the nominal coil diameter D, the spring can buckle under a sufficiently heavy
load.
The maximum allowable spring deflection Dmax that avoids buckling depends
on the free length, the coil diameter, and the spring ends (pivot ball, ground
& squared, etc.).
Buckling Thresholds
One quick method for checking for buckling is to compute the deflection to
free height ratio (D/Lfree) and use the following chart to check if the ratio
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exceeds the maximum allowable value:
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