INDRODUCTION
Pneumatic hole punching
helps to make the hole in sheet metal by using Compressed Air.
Pneumatic actuators controlled energy to the punch , so the Operator
needs to provide only modest effort regardless of conditions. Pneumatic
Punching machine helps to make hole in Various size by changing tool. As
well, pneumatic Punch provides some feedback of forces acting on the
Sheet and Hole can Made in Sheet metal.
Pneumatic Hole punching machine is reduce Effort To Operator. Operator Need Very Less amount of effort.
Pneumatic hole punching machine operated by compressed Air. Pneumatic
clamp have pneumatic Cylinder, 5/2 Flow control Hand Lever valve
USEFULLNESS OF THE PROJECT.
This Machine can Be Used many Application Can Be used In Many Industries Applications. It Operated by compressed Air.
It Simple Method , It is Used To Special sheet metal .
Some Industries. It can Operate Low Skilled Operator.
It Provide smooth Action To Work To make hole
It Can provide Flexibility to change sheets.
It Also Low cost compare with others.
TYEPE OF PUNCHING MACHINE
Flywheel drive
Most
punch presses today are hydraulically powered. Older machines, however,
have mechanically driven rams, meaning the power to the ram is provided
by a heavy, constantly-rotating flywheel. The flywheel drives the ram using a Pitman arm.
In the 19th century, the flywheels were powered by leather drive belts
attached to line shafting, which in turn ran to a steam plant. In the
modern workplace, the flywheel is powered by a large electric motor.
Mechanical punch press
Mechanical
punch presses fall into two distinct types, depending on the type of
clutch or braking system with which they are equipped. Generally older
presses are "full revolution" presses that require a full revolution of
the crankshaft for them to come to a stop. This is because the braking
mechanism depends on a set of raised keys or "dogs" to fall into
matching slots to stop the ram. A full revolution clutch can only bring
the ram to a stop at the same location- top dead center. Newer presses
are often "part revolution" presses equipped with braking systems
identical to the brakes on commercial trucks. When air is applied, a
band-type brake expands and allows the crankshaft to revolve. When the
stopping mechanism is applied the air is bled, causing the clutch to
open and the braking system to close, stopping the ram in any part of
its rotation.
Hydraulic punch press
Hydraulic punch presses, which power the ram with a hydraulic cylinder
rather than a flywheel, and are either valve controlled or valve and
feedback controlled. Valve controlled machines usually allow a one
stroke operation allowing the ram to stroke up and down when commanded.
Controlled feedback systems allow the ram to be proportionally
controlled to within fixed points as commanded. This allows greater
control over the stroke of the ram, and increases punching rates as the
ram no longer has to complete the traditional full stroke up and down
but can operate within a very short window of stroke.
Servo drive turret punch press
Servo drive turret punch press uses twin AC servo drives directly
coupled to the drive shaft. This drive system combines the simplicity of
the original clutch and brake technology with the speed of the
hydraulic ram driven systems. This results in high performance,
reliability, and lower operating costs. Servo drive press system doesn't
have complex hydraulics and oil-cooling chillers reducing maintenance
and repair costs. Turret press can be equipped with an advanced
technology that stores and reuses energy generated during ram
deceleration, providing extended electrical power savings
DESCRIPTION OF VARIOUS PARTS
1. Pneumatic Cylinder
2.5/2 Flow control Hand Lever Valve.
3.base plate.
4. Tool.
5. Bolts Nuts
6. Air Hoes.
1. Pneumatic Cylinder:
Pneumatic cylinders (sometimes known as air cylinders) are mechanical devices which use the power of compressed gas to produce a force in a reciprocating linear motion.
Like hydraulic cylinders, pneumatic cylinders use the stored potential
energy of a fluid, in this case compressed air, and convert it into
kinetic energy as the air expands in an attempt to reach atmospheric
pressure. This air expansion forces a piston
to move in the desired direction. The piston is a disc or cylinder, and
the piston rod transfers the force it develops to the object to be
moved. Engineers prefer to use pneumatics sometime because they are
quieter, cleaner, and do not require large amounts or space for fluid
storage.
Because the operating fluid is a gas, leakage from a pneumatic cylinder
will not drip out and contaminate the surroundings, making pneumatics
more desirable where cleanliness is a requirement. For example, in the
mechanical puppets of the Disney Tiki Room, pneumatics are used to prevent fluid from dripping onto people below the puppets.
Operation
General
Once
actuated, compressed air enters into the tube at one end of the piston
and, hence, imparts force on the piston. Consequently, the piston
becomes displaced (moved) by the compressed air expanding in an attempt
to reach atmospheric pressure.
Compressibility of gasses
One
major issue engineers come across working with pneumatic cylinders has
to do with the compressibility of a gas. Many studies have been
completed on how the precision of a pneumatic cylinder can be affected
as the load acting on the cylinder tries to further compress the gas
used. Under a vertical load, a case where the cylinder takes on the full
load, the precision of the cylinder is affected the most. A study at
the National Cheng Kung University in Taiwan, concluded that the
accuracy is about ± 30mm, which is still within a satisfactory range but
shows that the compressibility of air has an effect on the system.
Fail safe mechanisms
Pneumatic systems are often found in settings where even rare and brief system failure is unacceptable. In such situations locks can sometimes serve as a safety mechanism in case of loss of air supply (or its pressure falling) and, thus, remedy
or abate any damage arising in such a situation. Due to the leakage of
air from input or output reduces the pressure and so the desired output.
Types:
Although pneumatic cylinders will vary in appearance, size and
function, they generally fall into one of the specific categories shown
below. However there are also numerous other types of pneumatic cylinder
available, many of which are designed to fulfill specific and
specialized functions.
Single-acting cylinder
Single-acting cylinders (SAC) use the pressure imparted by compressed
air to create a driving force in one direction (usually out), and a
spring to return to the "home" position. More often than not, this type
of cylinder has limited extension due to the space the compressed spring
takes up. Another downside to SACs is that part of the force produced
by the cylinder is lost as it tries to push against the spring. Because
of those factors, single acting cylinders are recommended for
applications that require no more than 100mm of stroke length. :85
Double-acting cylinders
Double-acting cylinders (DAC) use the force of air to move in both
extend and retract strokes. They have two ports to allow air in, one for
outstroke and one for instroke. Stroke length for this design is not
limited, however, the piston rod is more vulnerable to buckling and
bending. Addition calculations should be performed as well.
Multi-stage, telescoping cylinders
Telescoping cylinders can be either single or double-acting. The
telescoping cylinder incorporates a piston rod nested within a series of
hollow stages of increasing diameter. Upon actuation, the piston rod
and each succeeding stage "telescopes" out as a segmented piston. The
main benefit of this design is the allowance for a notably longer stroke
than would be achieved with a single-stage cylinder of the same
collapsed (retracted) length. One cited drawback to telescoping
cylinders is the increased potential for piston flexion due to the
segmented piston design. Consequently, telescoping cylinders are
primarily utilized in applications where the piston bears minimal side
loading.
Other types
Although SACs and DACs are the most common types of pneumatic cylinder, the following types are not particularly rare.
- Through rod air cylinders: piston rod extends through both sides of the cylinder, allowing for equal forces and speeds on either side.
- Cushion end air cylinders: cylinders with regulated air exhaust to avoid impacts between the piston rod and the cylinder end cover.
- Rotary air cylinders: actuators that use air to impart a rotary motion.
- Rodless air cylinders: These have no piston rod. They are actuators that use a mechanical or magnetic coupling to impart force, typically to a table or other body that moves along the length of the cylinder body, but does not extend beyond it.
- Tandem air cylinder: two cylinders are assembled in series in order to double the force output.
- Impact air cylinder: high velocity cylinders with specially designed end covers that withstand the impact of extending or retracting piston rods.
Rodless cylinders
Some rodless types have a slot in the wall of the cylinder that is
closed off for much of its length by two flexible metal sealing bands.
The inner one prevents air from escaping, while the outer one protects
the slot and inner band. The piston is actually a pair of them, part of a
comparatively long assembly. They seal to the bore and inner band at
both ends of the assembly. Between the individual pistons, however, are
camming surfaces that "peel off" the bands as the whole sliding assembly
moves toward the sealed volume, and "replace" them as the assembly
moves away from the other end. Between the camming surfaces is part of
the moving assembly that protrudes through the slot to move the load. Of
course, this means that the region where the sealing bands are not in
contact is at atmospheric pressure.
Another type has cables (or a single cable) extending from both (or
one) end[s] of the cylinder. The cables are jacketed in plastic (nylon,
in those referred to), which provides a smooth surface that permits
sealing the cables where they pass through the ends of the cylinder. Of
course, a single cable has to be kept in tension.
Still others have magnets inside the cylinder, part of the piston
assembly, that pull along magnets outside the cylinder wall. The latter
are carried by the actuator that moves the load. The cylinder wall is
thin, to ensure that the inner and outer magnets are near each other.
Multiple modern high-flux magnet groups transmit force without
disengaging or excessive resilience.
Design
Construction
Depending on the job specification, there are multiple forms of body constructions available :
- Tie rod cylinders: The most common cylinder constructions that can be used in many types of loads. Has been proven to be the safest form.
- Flanged-type cylinders: Fixed flanges are added to the ends of cylinder, however, this form of construction is more common in hydraulic cylinder construction.
- One-piece welded cylinders: Ends are welded or crimped to the tube, this form is inexpensive but makes the cylinder non-serviceable.
- Threaded end cylinders: Ends are screwed onto the tube body. The reduction of material can weaken the tube and may introduce thread concentricity problems to the system
2. 5/2 Flow control Hand Lever Valve:
A Hand lever Flow Control valve is an mechanical valve for use with liquid or gas.
The valve is controlled by Mechanical through Hand Lever : in the case
of a two-port valve the flow is switched on or off; in the case of a
three-port valve, the outflow is switched between the two outlet ports.
Multiple valves can be placed together on a manifold.
Flow Control are the most frequently used control elements in fluidics.
Their tasks are to shut off, release, dose, distribute or mix fluids.
They are found in many application areas. This offer fast and safe
switching, high reliability, long service life, good medium
compatibility of the materials used, low control power and compact
design.
A valve has two main parts: the and the valve. The mchanical energy
which, in turn, opens or closes the valve mechanically. A direct acting
valve has only a small flow This diaphragm piloted valve multiplies this
small flow by using it to control the flow through a much larger
orifice.
Control valves may use metal seals or rubber seals, and may also have
electrical interfaces to allow for easy control. A spring may be used to hold the valve opened or closed while the valve is not activated.
.
When the Vave is again deactivated and the conduit D is closed again,
the spring needs very little force to push the diaphragm down again and
the main valve closes. In practice there is often no separate spring,
the elastomeric diaphragm is moulded so that it functions as its own
spring, preferring to be in the closed shape.
From
this explanation it can be seen that this type of valve relies on a
differential of pressure between input and output as the pressure at the
input must always be greater than the pressure at the output for it to
work. Should the pressure at the output, for any reason, rise above that
of the input then the valve would open regardless of the state of the
solenoid and pilot valve.
In some valves the acts directly on the main valve. Others use a
small, complete valve, known as a pilot, to actuate a larger valve.
While the second type is actually a valve combined with a pneumatically
actuated valve, they are sold and packaged as a single unit referred to
as a valve. Piloted valves require much less power to control, but
they are noticeably slower. Piloted usually need full power at all
times to open and stay open, where a direct acting may only need full
power for a short period of time to open it, and only low power to hold
it.
Types of control valve
The most common and versatile types of control valves are sliding-stem
globe and angle valves. Their popularity derives from rugged
construction and the many options available that make them suitable for a
variety of process applications, including severe service. Control
valve bodies may be categorized as below:
Globe control valve with pneumatic actuator and smart positioner
- Angle valves
- Cage-style valve bodies
- DiskStack style valve bodies
- Angle seat piston valves
- Globe valves
- Single-port valve bodies
- Balanced-plug cage-style valve bodies
- High capacity, cage-guided valve bodies
- Port-guided single-port valve bodies
- Double-ported valve bodies
- Three-way valve bodies
- Diaphragm Valves
- Rotary valves
- Butterfly valve bodies
- V-notch ball control valve bodies
- Eccentric-disk control valve bodies
- Eccentric-plug control valve bodies
- sliding cylinder valves
- Directional control valve
- spool valve
- piston valve
- air operated valves
- air operated valve
- relay valve
- air operated pinch valve
4. Tool:
Punch tooling (punch and die) is often made of hardened steel or tungsten carbide.
A die is located on the opposite side of the workpiece and supports the
material around the perimeter of the hole and helps to localize the
shearing forces for a cleaner edge. There is a small amount of clearance
between the punch and the die to prevent the punch from sticking in the
die and so less force is needed to make the hole. The amount of
clearance needed depends on the thickness, with thicker materials
requiring more clearance, but the clearance is always less than the
thickness of the workpiece. The clearance is also dependent on the
hardness of the workpiece. The punch press forces the punch through a
workpiece, producing a hole that has a diameter equivalent to the punch,
or slightly smaller after the punch is removed. All ductile materials
stretch to some extent during punching which often causes the punch to
stick in the workpiece. In this case, the punch must be physically
pulled back out of the hole while the work is supported from the punch
side, and this process is known as stripping. The hole walls will show
burnished area, rollover, and die break and must often be further
processed. The slug from the hole falls through the die into some sort
of container to either dispose of the slug or recycle it.
WORKING PRICIPLE
Punching is a metal forming process that uses a punch press to force a tool, called a punch, through the workpiece to create a hole via shearing. The punch often passes through the work into a die.
A scrap slug from the hole is deposited into the die in the process.
Depending on the material being punched this slug may be recycled and
reused or discarded. Punching is often the cheapest method for creating
holes in sheet metal in medium to high production volumes. When a
specially shaped punch is used to create multiple usable parts from a
sheet of material the process is known as blanking. In forging
applications the work is often punched while hot, and this is called hot
punching
Punch tooling (punch and die) is often made of hardened steel or tungsten carbide.
A die is located on the opposite side of the workpiece and supports the
material around the perimeter of the hole and helps to localize the
shearing forces for a cleaner edge. There is a small amount of clearance
between the punch and the die to prevent the punch from sticking in the
die and so less force is needed to make the hole. The amount of
clearance needed depends on the thickness, with thicker materials
requiring more clearance, but the clearance is always less than the
thickness of the workpiece. The clearance is also dependent on the
hardness of the workpiece. The punch press forces the punch through a
workpiece, producing a hole that has a diameter equivalent to the punch,
or slightly smaller after the punch is removed. All ductile materials
stretch to some extent during punching which often causes the punch to
stick in the workpiece. In this case, the punch must be physically
pulled back out of the hole while the work is supported from the punch
side, and this process is known as stripping. The hole walls will show
burnished area, rollover, and die break and must often be further
processed. The slug from the hole falls through the die into some sort
of container to either dispose of the slug or recycle it
This Pneumatic hole Punching machine Have Pneumatic cylinder, 5/2 Flow
control Valve, Tool Arrangements , bolts Nut Supporting pillar.
When The air from compressor, it will be taking a decision to move the
tool down. Also it will up and down movement when the obstacle crossing
time that will also press sheet with the help of pneumatic cylinder, and
it will be given to the hand lever valve and then it will move up or
down depends upon the air speed. The tool movement and Up, down can be
done with the help of pneumatic cylinder.
This machine are mostly used in Industrial use to Mass Production It can punch hole rapidly and Multi size Jobs.
It Have 10 bar maximum Pressure capacity . It can clamp 1 mm to 2mm thickness work pieces.
It cost also less, high efficiency, work loading time is less.
ADVANTAGES
- Simplicity of Design And Control
- Machines are easily designed using standard cylinders & other components. Machines operate by simple ON - OFF type control.
- Reliability
- Pneumatic systems tend to have long operating lives and require very little maintenance.
- Because gas is compressible, the equipment is less likely to be damaged by shock. The gas in pneumatics absorbs excessive force, whereas the fluid of hydraulics directly transfers force.
- Storage
- Compressed gas can be stored, allowing the use of machines when electrical power is lost.
- Safety
- Very low chance of fire (compared to hydraulic oil).
- Machines can be designed to be overload safe
DISADVANTAGES:
1. Additional Arrangement Required Cost is Required.
2. Any Place Air Leak This System May Be fail.
APPLICATION
1. Bus body making .
2. sheet metal trays hole punching.
2. Flange Plates Some parts Used This Method To make the hole. Their Work is also used in tool Room.
