How pneumatic cylinders are different from hydraulic cylinders where each one is used

8/8/2019 How pneumatic cylinders are different from hydraulic cylinders where each one is used

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TERM PAPER

Subject: FLUID MECHANICS

Topic: How pneumatic cylinders are different from

hydraulic cylinders where each one is used

Submitted by:

RAHUL KUMAR

Regd no: 10901641

Section:F4901

Roll no: B32



ACKNOWLEGDEMENT

I devote all my achievements to the almighty µGOD¶ for granting me

strength, art, skill and spirit to accomplish and every point in simplest

possible way .I am also thankful to my µParents¶ for their encouragement

and kind cooperation throughout the course of this project .I am also

thankful to my very good friends for helping me to get best ideas, for gathering data, for accumulation of information and other valuable

things .They also assisted me in analyzing, evaluating and presenting it

in the best possible way under the available means.

Hydraulic Equipment

A Hydraulic Cylinder produces linear motion and force by using pressurized hydraulicfluid. Industrial machines powered by hydraulic cylinders are able to form metals or other materials at a very high force with a relatively small supply of highly pressurizedfluid.

Heavy equipment, such as an excavator, relies on the power of hydraulic fluid. Theoperator easily controls the pressurized hydraulic fluid with the use of a control valveconnected to distributor hoses and tubes. A solenoid valve is the type of valve mostcommonly used with a hydraulic cylinder as it has a reputation of safety and reliability.Valves not only control the release of fluid in the hydraulic cylinder, but often mix gasesand fluids as well. When the brake pedal is depressed, the pedal pushes on the piston

in the master hydraulic cylinder and the slave pistons located at each wheelworktogether to stop the car.

Hydraulic seals are crucial in relation to the safe functioning of a hydraulic cylinder.Industries that use heavy equipment, such as automotive, aerospace, government, oil,and gas rely on improving hydraulic seal technology. The explosion of the Challenger space shuttle in 1986 was mainly attributed to malfunctioning hydraulic seals caused bylow temperatures that solidified the seal's inner material, thus preventing a proper seal.



Worn out hydraulic seals also present safety concerns, but can often be prevented byusing a hydraulic cylinder with a smooth inside surface.

BACKGROUND OF

THE INV

EN

TION

Multiple lifters using hydraulic or pneumatic cylinders are used in a variety of environments. The lifters may be used to raise and lower vehicles in service stationsand repair centers as well as being used in robotics and assembly line production. Inthe case of an assembly line, multiple lifters may be required to vertically or laterallymove a manufactured part simultaneously and at the same rate. It is often critical thatthe multiple lifters and the associated cylinders maintain the same extension during themanufactured process even when the load on the lifters or cylinders are unequal.Synchronizing cylinders assemblies have often used single rod cylinders.

The use of single rod cylinders has always had one drawback, being that the cylinder has a different volume displacement from the extension of the cylinder rod to theretraction of the cylinder rod. This is due to the rod diameter on one side of the piston,which makes the use of cylinders for the synchronizing of multiple units very difficult.Thus, other cylinder types have been developed.

First, there is the double rod cylinder, which equalizes the displacement with a rod onboth sides of the piston. However, this creates a space issue. The design must nowincorporate extra room for the cylinder rod that extends out the opposite end of thecylinder.

Second, there is the rodless cylinder. This cylinder has a carriage for mounting, asopposed to a threaded rod end, which is either mechanically or magnetically coupled tothe piston. This design also has a drawback. The magnetically coupled carriage can beuncoupled from the piston while the mechanism is functioning. This uncoupling cancause machine failure or even extreme damage to the machine, while the mechanicallycoupled unit is prone to leakage and is not suitable for a hydraulic application.

Important Features Of Hydraulic Jacks

- The portable device is also able to exert large forces. The jacks are usually used to

work and shop are commonly used for lifting equipment heavyweight. A hydraulic jack isa mechanical device is mainly used for lifting heavy loads. It is very lightweight and

compact. It is also important to ensure the stability of the outlet when it is extended.

These powerful shots require special care in choosing the to site conditions and jacking

points on the vehicle.



Functions Of Hydraulic Jacks

| A hydraulic jack is a mechanical device mainly used to lift heavy loads. It's very light

and compact. The device itself is also portable and capable of exerting great forces.

Hydraulic jacks are usually used for shop work and are commonly used for lifting heavy

weight equipment. These powerful jacks require extra care when choosing the ground

conditions and jacking points on the vehicle. It's also very important to ensure the jack's

stability when it's extended. The portable device is also able to exert large forces. The

jacks are usually used to work and shop are commonly used for lifting equipment

heavyweight. A hydraulic jack is a mechanical device is mainly used for lifting heavy

loads. It is very lightweight and compact. It is also important to ensure the stability of the

outlet when it is extended. These powerful shots require special care in choosing the to

site conditions and jacking points on the vehicle.

SUMMARY OF THE INVENTION

It is the intent of the present invention to address the aforementioned concerns. According to the invention a close circuit synchronizing cylinder assembly is providedfor synchronizing at least two external devices having a movable member withreciprocal movement such that the devices move at the same rate and stay level to

each other within a small deviation throughout the cyclic movements of the movablemembers. In one aspect of the invention the synchronizing cylinder assembly includes ahydraulic cylinder for each external device wherein each hydraulic cylinder communicates with the other hydraulic cylinder in a closed circuit system. The hydrauliccylinder includes a piston slidable within the hydraulic cylinder and a piston rodprojecting from a rod end of the cylinder. The interior of the cylinder is divided into 3chambers. The rod outer diameter, rod inner diameter and cap end chambers. The rodouter diameter chamber and the rod inner diameter chamber encapsulate hydraulicfluid, while the third chamber is open to atmosphere. Multiple cylinders communicatewith each other such that the hydraulic fluid in the rod outer diameter chamber of onecylinder communicates with hydraulic fluid in the rod inner diameter chamber in another

cylinder.

In another aspect of the invention the synchronizing cylinder assembly includes ameans for communicating fluid from the third chamber of the cylinder to a reservoir assembly. The reservoir assembly includes an inside chamber with an exhaust portopen to atmosphere and means for directing hydraulic fluid that passes through sealsinto the third chamber, to a rod outer diameter chamber or rod inner diameter chamber of the cylinder.



In a further aspect of the invention, the cylinder has a means of bleeding air from thecylinder.

In another aspect, the cylinder includes an equalizing vent communicating between the

rod outer diameter chamber and the rod inner diameter chamber to allow minimal fluidto pass therethrough to compensate for any seal leakage that would otherwise preventfull cylinder stroke.

Electric Rod Actuators Challenge Pneumatic Cylinders

The US actuator specialist Tolomatic has developed a range of electric rod-styleactuators as an economical alternative to non-repairable pneumatic cylinders, and for automating manual processes. The ERD actuators deliver forces of up to 334N at

speeds of up to 1,016mm/s.

Aaron Dietrich, Tolomatic¶s electric productsmanager, says that the patent-pending actuators (shown above) ³provide an alternativeto pneumatic cylinders with the added benefit of greater control of speed, accelerationand force´. They also offer an ³affordable option for automating manual processes´.

The round-bodied electric actuators are available in sizes equivalent to 5/8, 1 and 1.5-inch bore non-repairable pneumatic cylinders. They accept Nema 11, 17 or 23 frame

stepper and servomotors, and the acme leadscrews are available in three lead sizes per model to optimise speed or force.

The actuators, which come with metric-threaded rod-ends, can accommodate sixdifferent sensing or switching technologies including reed, solid-state PNP or NPN,normally open, flying leads or quick-disconnect. The switches are activated by a magnetinside the thrust tube.



TRD Manufacturing Introduces the MH Series and TAS Cylinders

Machesney Park, IL ± TRD Manufacturing, a Bimba Company, announced the introduction of

the new MH Series and TAS Series Cylinders designed to deliver more reliability in heavy-dutyindustrial operations.

MH Series

The MH Series are medium pressure hydraulic cylinders rated for 675 to 1500 psi (depending on bore size). The TAS Series Steel Pneumatic Cylinders are rated for 250 psi air and 400 psihydraulic (with TH option). Both models are available in bore sizes 1.50´, 2´, 2.50´, 3.25´, 4´,

5´, 6´ and 8´.

TAS Series



Standard features include a heavy-duty rod wiper, seals, wear band, chrome plated I.D. tube andmore. Rod locks, stop tubes, center supports, stainless steel piston rods and high impact pistons

are also available as performance options. Accessories include clevis, pins, mounts andalignment couplers, with up to a 5´ thread size.

Accurate Force Pneumatics from Airpot

Airpot Corp. has developed a line of products and systems, which excel in applications requiring

precise, accurate control of actuation, damping, or displacement. Using high quality pneumaticsin conjunction with Airpot¶s precision glass cylinder and graphite piston technology, Airpot now

offers designers levels of force and motion control unobtainable by other pneumatic means. Evenzero friction actuation is possible, allowing for ultra precise measurement, application of minute

forces, and sub-micron control of linear displacement. Ideal for uses such as high tech micromachining, polishing or grinding equipment, Airpot¶s pistons and cylinders are manufactured to

extremely tight tolerances and have special properties which also allow for precise volumetricdisplacements in the micro-liter range for sampling applications requiring the movement or

measurement of a volume of air or gas.

Each of the product groups offers instrument quality pneumatic devices uniquely designed and

optimized for highly accurate and repeatable force control at lower cost than other methods providing comparable functions and performance. The result is products and systems that Damp,

Actuate, and Displace with superior accuracy and little or no friction. Airpot Accurate ForcePneumatics are ideal for designing or improving a product line or building specialized equipment

to do research, high level testing or precision assembly.

Airpot¶s ³Accurate Force Pneumatics´ individual component products aid the designer in the

following three areas, and Airpot¶s optimized systems provide the ultimate in customized force

control.



Damping: When there is the need to reduce or eliminate harmful or excessive motion Air Dashpots andShock Absorbers use ambient air to precisely and accurately control force, velocity and impact.

Actuation: When your mechanism needs a precise force Airpot Self aligning Actuators, Anti-Stiction andZero-Friction air cylinders allow you to move it, hold it, or press it accurately and with amazing

repeatability.

Displacement: Precision Piston /Cylinder sets and Self-Aligning actuators make possible the precise dispensingof small volumes of air in pumping and flow applications, and can also be used for specialized

bearing or driving requirements.

Optimized Systems: Pre-selected systems components provide most of the functions needed between the air supply

and the force output system to achieve your actuation objectives, and can save you research anddevelopment time. Our systems are matched to insure optimum performance and lowest cost.

Dual-sensor, Split-connector Cuts Cylinder Costs

Three areas where you can look to cut costs on pneumatic cylinder applications includeinstallation time, cables, and the sensors used for detecting the piston¶s position. For example, first consider the sensor in a standard cylinder. Most standard cylinders use



proximity switches, either internal or external to the aluminum housing that detectspecial targets or magnets mounted on the piston. Unfortunately, these proximityswitches can be relatively expensive, take up valuable space, and are difficult and time-consuming to install.

A dual-sensor, split-connector system coupled to a multiple-interface block (MIB) in a high-density application reduces the number of wires and potentially doubles the number of cylinder

switches that can be used in the same installation.

A better solution is designed around a new dual sensor with a split connector. The configurationhas two low-profile, magnetic-field sensors molded together into a single, four-pole connector.

Compared to the standard application (where the end of the piston¶s stroke is detected in bothdirections), the dual sensor system does the same job with one less connecting cable,

fewer terminations, and less connective hardware, which require less time to install. This dualsensor arrangement can cut an application¶s cost by 50%.

Important Features Of Hydraulic Jacks

- The portable device is also able to exert large forces. The jacks are usually used to

work and shop are commonly used for lifting equipment heavyweight. A hydraulic jack is

a mechanical device is mainly used for lifting heavy loads. It is very lightweight and

compact. It is also important to ensure the stability of the outlet when it is extended.

These powerful shots require special care in choosing the to site conditions and jacking

points on the vehicle.



Festo round cylinders DS NU are now available with self-adjusting pneumatic cushioning.

(Photo: Festo)

Until now, users always needed to adjust the end-position cushioning integrated into cylinders

manually, with the risk of slow cycle times or excessive noise generation. Manual adjustment of end-position cushioning also takes time; this makes commissioning a very long drawn-out

process in the case of installations with a lot of drives requiring cushioning.

Without any need for manual interventions, self-adjusting cushioning PPS from Festo nowensures an optimum cushioning action every time, even if parameters such as friction and

pressure change. It also reduces the acceleration forces acting on components and workpieces.This cuts down wear and minimises time-consuming vibration. What is more, in comparison

with shock absorbers, self-adjusting cushioning is less expensive and more robust. This uniquecushioning, not offered by any other supplier, is now available with the Festo round cylinder

DS NU, of which millions of examples have already been sold.



With Festo¶s self-adjusting cushioning PPS for round cylinders DS NU, longitudinal slots on the

inside of the cylinder discharge exhaust air in a controlled way, thus making it possible toachieve dynamic but gentle cushioning action into the end positions without the need for manual

intervention. (Photo: Festo)

The DS NU-PPS variant with self-adjusting cushioning described above is not the only member

of the DS NU range to offer impressive performance. In addition to the basic, standardisedversion, DS NU is available with four different mounting options, created by combinations of a

total of three different bearing caps and four end caps. This include end caps of block design for

direct mounting or with flange threads, end caps with threaded lugs and swivel bearings, with air supply connections that are lateral or in-line with the cylinder axis. The advantages for customersare: no need for costly special solutions, more flexibility during system design and less work

when ordering. To ensure that ordering remains transparent and simple, the wide variety of available piston diameters, stroke lengths, functions and variants can be selected with just a

single order code. Further variants are available with a through piston rod, heat-resistant sealsand clamping units.

The DS NU covers all the applications within the ISO 6432 standard but also goes well beyond

this. It will appeal to all users who place the most stringent requirements on round cylinders withregard to quality, a wide choice of variants, availability and price/performance ratio. The well-

known long service life of Festo cylinders helps ensure system availability and thus guaranteemaximum productivity.

DUAL SENSOR FOR C-GROOVE CYLINDERS

TURCK¶s BIM-UNR line of compact magnetic cylinder positionsensors now includes a dual sensor designed for detecting short and long stroke C-groove cylinders. BIM-UNR dual sensors provide a distinctadvantage by combining two sensors through one cable connection to speed installation, as well as lessen



wire costs and connection points. This design makes the sensor particularly beneficial in areas wheremultiple cylinders are used, as it only requires a single cable. With dimensions of 2.9 x 4.6 x 18 mm,

Delivering reliable performance and high EMC immunity, thisl sensor provides an exceptional

alternative to ordinary cylinder position sensors. The sensor mounts within C-groove cylinderswith no accessories required. Plus, it can be inserted into a C-groove from the top rather thanfrom the side, further simplifying installation. On the sensor¶s side is a built-in tab that keeps the

sensor in place to facilitate one-handed mounting. As the mounting screw is located near thecable exit, the sensor remains fastened even if the cable is pulled.

CPS Series offers Cylinder PostionSwiches

NITRA announced its new product, the CPS Series of pneumatic cylinder positionswitches.Using state-of-the-art AMR magnetic sensing technology, these switches are designed

for use with pneumatic cylinders that have a magnet incorporated in the cylinder piston. They

can be used to provide cylinder position indication, cycle count or to confirm operation.



The NITRA CPS Series is available in 3-wire DC, P NP normally open, P NP normally closed,and NP N normally open electronic solid state switch configurations with either an M8 wiring

connector or wire leads. Designed to provide a low profile, flush installation on cylinders with T-slot channels, these switches are also easily mounted on round body cylinders using CPSB series

mounting bands. Integral LED indication provides switch status for speedy switch positioning

and troubleshooting. Pre-tested for use with N

ITRA pneumatic cylinders, the CPS Series is alsosuitable for use with other brands of cylinders with magnetic pistons.

CONCLUSION

y www.georgefischer.com

y www.festo.com

y http://www.pneumatictips.com/pneumatic-equipment-components/dual-sensor-split-connector-cuts-cylinder-costs/

y http://www.articlesnatch.com/topic/hydraulic+cylinders#ixzz14hQGICqy

How pneumatic cylinders are different from hydraulic cylinders where each one is used

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