hydro pneumatic clamping project

[AwarseAcrobre]

Introduction: Fluid power technology actually began in 1950 with the discovery of
Pascal's law: Pressure is transmitted undiminished in a confined body of fluid. Pascal
found that when he rammed a cork down into a jug completely full of wine, the bottom of
the jug broke and fell out. Pascal's law indicated that the pressures were equal at the top
and bottom of the jug. However, the jug has small opening area at the top and a large area
at the bottom. Thus, the bottom absorbs a greater force due to its larger area.
Combination of pneumatics coupled with hydraulics are used to lift large amount of load
with more precision and accuracy. The combination system eliminates the limitations of
individual systems of hydraulics and pneumatics like costly hydraulic pumps and
hydraulic direction control valves in addition to reduction in operating and maintenance
costs. Pressurized air of 3 bar from the compressor hits the piston (60 mm diameter) of the
single acting pneumatic cylinder from the blank end side via three ports and two positions
(3/2) push button operated directional control valve. As a result, the piston of the
pneumatic cylinder extends. This in turn pressurizes (12 bar) the enclosed oil in the
hydraulic line, as per Pascal s law. This could be due to the extension of the rod (30 mm
diameter) of the piston of the pneumatic cylinder, and surprisingly, the rod acts as piston to
the hydraulic line. The pressurized fluid of 12 bar will act on the blank end of the piston
(100 mm diameter) of the single acting hydraulic cylinder. A large amount of load
carrying capacity of approximately 9400 kg would be delivered by the hydraulic cylinder
rod. This could be achieved by connecting metallic plate (or pan) to the rod of the
hydraulic cylinder by means of nuts and bolts. This arrangement can be used for lifting the
loads as well as to clamp the workpiece on the table during machining. As the push button
of 3/2 DCV is depressurized, trapped pressurized air from the pneumatic cylinder is vented
to the atmosphere freely. Consequently, the oil from the hydraulic cylinder reverts back to
the reservoir (hydraulic line). The cylinder will be retracted and load is released.
Objectives:
To design a machine that can achieve high accuracy in lifting using smooth and
efficient fluid power.
To eliminate the use of hydraulic pump in hydraulic systems.
Controlled lifting of load.
To minimize initial cost, operating cost and maintenance cost.
Methodology: Air from a single stage air compressor enters the push button direction
control valve and is directed to the pneumatic actuator. The pneumatic actuator is a double
acting cylinder and the compressed air extends the piston. The piston rod acts as piston in
the hydraulic line and pressurizes the hydraulic fluid. Thus the hydraulic fluid enters the
delivery pipe through a filter arrangement. The pressurized fluid is made to act on a
hydraulic cylinder placed on a table arrangement. The hydraulic fluid then extends the
hydraulic piston. The end of the piston rod is connected to a load pan. Thus the pan
extends along with the piston rod and lifts the load.
Pressurized air at 3bar from the compressor hits the piston (120mm diameter) of the double
acting pneumatic cylinder from the blank end side via five ports and two positions (5/2)
push button operated directional control valve. As a result, the piston of the pneumatic
cylinder extends. This in turn pressurizes (up to 69 bar) the enclosed oil in the hydraulic
line, as per Pascal s law. This is due to the extension of the piston rod (120mm diameter)
of the pneumatic cylinder and the rod acts as piston to the hydraulic line. The pressurized
fluid at 69bar will act on the blank end of the piston (50mm diameter) of the single acting
hydraulic cylinder. A large amount of load carrying capacity of approximately 1300Kg
would be delivered by the hydraulic cylinder rod. This could be achieved by connecting
metallic plate (or pan) to the rod of the hydraulic cylinder by means of nuts and bolts. This
arrangement can be used for lifting the loads as well as to clamp the work piece on the
table during machining. By operating push button of the 5/2 DCV, air from the compressor
enters into the pneumatic cylinder through the rod end side. This makes the piston to
retract and the oil from the reservoir is drawn into booster portion of the pneumatic
cylinder. By depressurizing the push button of 5/2 DCV, the spool of the DCV assumes
its initial position. As a result, air pressure on the blank end side of the cylinder pushes the
rod of the piston into the booster area. High force delivered by the piston creates an
increase in the pressure of the fluid, which in turn enters into the blank end region of the
single acting hydraulic cylinder. This causes rising of the load via the cylinder, which
depends on the cross sectional area of the piston. In order to lower the load cylinder
(hydraulic), needle valve connected to the main hydraulic line is operated, which causes
the draining of the oil from the hydraulic cylinder to the reservoir.
Results and Conclusion: Combination of pneumatics coupled with hydraulics is used to
lift large amount of load with more precision and accuracy. The combination system
eliminates the limitations of individual systems of hydraulics and pneumatics like costly
hydraulic pumps and hydraulic direction control valves in addition to reduction in
operating and maintenance costs.
1. Large delivery of oil per stroke allows quick filling of cylinders for clamping or
punching.
2. Pressure multiplication of the booster is responsible for carrying higher load.
3. High speed operation with constant hydraulic output (load carrying capacity).
4. Combination of pneumatics coupled with hydraulics is used to lift large amount of
load with more precision and accuracy.
5. The combination system eliminates the limitations of individual systems of hydraulics
and pneumatics like costly hydraulic pumps and hydraulic direction control valves in
addition to reduction in operating and maintenance costs.
Scope for Future work: By increasing the operating air pressure from 3 bar to 6 bar, the
maximum amount of load that can be lifted (theoretically) increases from 1383 kg to 2766
kg. Further varying the dimensions of the cylinders, it is possible to carry heavier loads
(than the above described load) that can be used to lift and/or to apply the force during
clamping of the component during mechanical working processes like machining, etc

[vishnu mohan]

Introduction: Fluid power technology actually began in 1950 with the discovery of
Pascal's law: Pressure is transmitted undiminished in a confined body of fluid. Pascal
found that when he rammed a cork down into a jug completely full of wine, the bottom of
the jug broke and fell out. Pascal's law indicated that the pressures were equal at the top
and bottom of the jug. However, the jug has small opening area at the top and a large area
at the bottom. Thus, the bottom absorbs a greater force due to its larger area.
Combination of pneumatics coupled with hydraulics are used to lift large amount of load
with more precision and accuracy. The combination system eliminates the limitations of
individual systems of hydraulics and pneumatics like costly hydraulic pumps and
hydraulic direction control valves in addition to reduction in operating and maintenance
costs. Pressurized air of 3 bar from the compressor hits the piston (60 mm diameter) of the
single acting pneumatic cylinder from the blank end side via three ports and two positions
(3/2) push button operated directional control valve. As a result, the piston of the
pneumatic cylinder extends. This in turn pressurizes (12 bar) the enclosed oil in the
hydraulic line, as per Pascal s law. This could be due to the extension of the rod (30 mm
diameter) of the piston of the pneumatic cylinder, and surprisingly, the rod acts as piston to
the hydraulic line. The pressurized fluid of 12 bar will act on the blank end of the piston
(100 mm diameter) of the single acting hydraulic cylinder. A large amount of load
carrying capacity of approximately 9400 kg would be delivered by the hydraulic cylinder
rod. This could be achieved by connecting metallic plate (or pan) to the rod of the
hydraulic cylinder by means of nuts and bolts. This arrangement can be used for lifting the
loads as well as to clamp the workpiece on the table during machining. As the push button
of 3/2 DCV is depressurized, trapped pressurized air from the pneumatic cylinder is vented
to the atmosphere freely. Consequently, the oil from the hydraulic cylinder reverts back to
the reservoir (hydraulic line). The cylinder will be retracted and load is released.
Objectives:
To design a machine that can achieve high accuracy in lifting using smooth and
efficient fluid power.
To eliminate the use of hydraulic pump in hydraulic systems.
Controlled lifting of load.
To minimize initial cost, operating cost and maintenance cost.
Methodology: Air from a single stage air compressor enters the push button direction
control valve and is directed to the pneumatic actuator. The pneumatic actuator is a double
acting cylinder and the compressed air extends the piston. The piston rod acts as piston in
the hydraulic line and pressurizes the hydraulic fluid. Thus the hydraulic fluid enters the
delivery pipe through a filter arrangement. The pressurized fluid is made to act on a
hydraulic cylinder placed on a table arrangement. The hydraulic fluid then extends the
hydraulic piston. The end of the piston rod is connected to a load pan. Thus the pan
extends along with the piston rod and lifts the load.
Pressurized air at 3bar from the compressor hits the piston (120mm diameter) of the double
acting pneumatic cylinder from the blank end side via five ports and two positions (5/2)
push button operated directional control valve. As a result, the piston of the pneumatic
cylinder extends. This in turn pressurizes (up to 69 bar) the enclosed oil in the hydraulic
line, as per Pascal s law. This is due to the extension of the piston rod (120mm diameter)
of the pneumatic cylinder and the rod acts as piston to the hydraulic line. The pressurized
fluid at 69bar will act on the blank end of the piston (50mm diameter) of the single acting
hydraulic cylinder. A large amount of load carrying capacity of approximately 1300Kg
would be delivered by the hydraulic cylinder rod. This could be achieved by connecting
metallic plate (or pan) to the rod of the hydraulic cylinder by means of nuts and bolts. This
arrangement can be used for lifting the loads as well as to clamp the work piece on the
table during machining. By operating push button of the 5/2 DCV, air from the compressor
enters into the pneumatic cylinder through the rod end side. This makes the piston to
retract and the oil from the reservoir is drawn into booster portion of the pneumatic
cylinder. By depressurizing the push button of 5/2 DCV, the spool of the DCV assumes
its initial position. As a result, air pressure on the blank end side of the cylinder pushes the
rod of the piston into the booster area. High force delivered by the piston creates an
increase in the pressure of the fluid, which in turn enters into the blank end region of the
single acting hydraulic cylinder. This causes rising of the load via the cylinder, which
depends on the cross sectional area of the piston. In order to lower the load cylinder
(hydraulic), needle valve connected to the main hydraulic line is operated, which causes
the draining of the oil from the hydraulic cylinder to the reservoir.