Work Performers of Pneumatic Systems

Work Performers of Pneumatic Systems
Chapter 17 Work Performers of Pneumatic Systems Cylinders, Motors, and Other Devices

Objectives Describe the construction features of basic, pneumatic linear and rotary actuators. Compare the design and operation of pneumatic cylinders. Compare the design and operation of pneumatic motors. Explain the performance characteristics used to rate the operation of pneumatic motors. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Objectives Describe the basic design and operation of specialized pneumatic tools commonly used in consumer and industrial applications. Size pneumatic cylinders and motors to meet the force and speed requirements of a basic work application. Interpret manufacturer specifications for basic, pneumatic cylinders, motors, and power tools. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic Actuators Pneumatic systems convert the potential energy of compressed air into force and movement using: Cylinders Motors Variety of other specially designed actuators and processes © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic Actuators Cylinders provide straight-line movement and force for use in mechanically operated equipment Often called linear actuators Force generated is controlled by system pressure Speed of movement is determined by the volume of air allowed to enter the unit © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic Actuators Pneumatic motors convert the potential energy of compressed air into torque and rotary movement Often called rotary actuators Torque depends on air pressure and the internal structure of the motor Operating speed is determined by the internal displacement of the motor per revolution and the volume of compressed air passing through the motor © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic Actuators Other processes and actuator designs use compressed air to assist in or complete a task Reciprocating movement Process assistance Nozzles Impact tools © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic Cylinder Construction
Typical pneumatic cylinders Parker Hannifin © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

The basic structure of pneumatic cylinders is very similar to those used in hydraulic systems Lower system operating pressures allow the use of lighter materials in pneumatic-system components Water vapor present in compressed air requires the use of corrosion-resistant materials or coatings for component parts © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Basic pneumatic cylinder construction IMI Norgren, Inc. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Some manufacturers produce nonlubricated pneumatic cylinders Do not require the addition of oil to the system compressed air Special coatings on the surface of the cylinder bore and other bearing surfaces provide lubrication Coatings are not scraped off during the operation of the actuator © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Resilient seals prevent both internal and external leaks IMI Norgren, Inc. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic cylinders may be single or double acting The operating principles of single-acting and double-acting pneumatic cylinders are basically the same as the cylinders designed for hydraulic applications © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Typical, single-acting cylinder IMI Norgren, Inc. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

The construction techniques used to manufacture pneumatic cylinders are very similar to those used to produce hydraulic cylinders Lower operating pressures allow some difference in construction Cylinder ends and barrel may be attached by metal rolling, rather than with tie rods, threads, or snap rings © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Rolled-metal ends on a cylinder Parker Hannifin © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic Cylinder Sizing
Two factors are basic to determining required actuator size Cylinder force output Absolute air consumption required to produce desired system performance © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

The force output of a cylinder is determined by system air pressure and the effective area of the cylinder piston F = P × A © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Air consumption of a cylinder can be estimated Calculate the volume of air displaced during one cycle of the cylinder Multiplying it by the number of cycles per minute and the absolute pressure ratio CFM = V × Pr × N © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Two factors make the accurate calculation of air consumption in a pneumatic system difficult Air leaks Variations in the actual volume of cylinder air chambers © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Manufacturers provide a variety of specific information about the cylinders they produce Construction materials Available sizes Pressure ratings Specific features such as cushions and mountings © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic Rotary Motors
Typical rotary motors Atlas Copco © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic motors are used to power: Many large stationary machines A large variety of portable hand tools These motors range in size from fractional-horsepower units to motors producing over 50 horsepower © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Air motors are available in many designs Vane Piston Turbine Other, specialized designs The vane air motor is the most common design © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Vane motors can be found in hand tools and large, stationary installations Atlas Copco © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Operation of a vane motor © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Piston air motors are most often found in installations requiring higher horsepower output They are available in both axial and radial piston designs © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Parts of an axial-piston motor © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Turbine motors incorporate air nozzles to direct air onto a turbine Nozzle produces high-speed air, which results in very high output-shaft speeds In specialized applications, the speed of turbine motors can reach 100,000 rpm © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Turbine air motor Atlas Copco © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Most manufacturers of rotary air motors publish tables and graphs that provide details about: Horsepower Torque Air consumption These data cover a wide range of operating speeds © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic Reciprocating Motors
Pneumatic reciprocating motors use percussive or nonpercussive techniques to transfer energy from compressed air to a workpiece Percussive tools provide multiple, physical impacts to overcome resistance Nonpercussive devices generally repeat a cycle to provide linear motion that is used to directly operate a machine © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Total input force of a percussion-type reciprocating motor is determined by: System air pressure Area of the piston © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

The paving breaker is a very common application of a reciprocating motor Often called a jackhammer Used in a number of applications Models available ranging in size from hand tools to large units mounted on mobile support equipment © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Example of a reciprocating motor Atlas Copco © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Reciprocating motors are used to power a variety of tools found in the foundry, construction, and general metal fabrication industries Scaling hammers Chipping hammers Riveting hammers Tampers Rammers © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Chipping hammers are used in foundries Atlas Copco © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Using a tamper on a casting mold Badger Iron Works, Inc. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Reciprocating motors commonly operate from under 1000 to over 3000 movements per minute of operation The operating rate depends on the task performed and the type of material being cleaned, formed, or trimmed © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Other Pneumatic-Powered Functions and Equipment
Compressed air is often used to assist functions without applying force to linear or rotary actuators Spraying Drying Material agitation Material transfer © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Insecticide is usually sprayed USDA © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Compressed air is used to agitate material Assure proper mixing of liquids Prevent the settling of solid materials in a suspension Provide oxygenation © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Agitation is used in sewage treatment © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

A nozzle is a very important device in many systems using compressed air In turbine motors, nozzles produce rapid airflow to assure the high speed rotation of the turbine output shaft Nozzles may be convergent or convergent-divergent © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Nozzle designs © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

A blowgun is a simple example of a nozzle IMI Norgren, Inc. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Blowguns are simple tools, but must be very carefully handled Produce high air velocity Can cause serious injury Designs are available with a bleed-off to increase safety © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Bleed-off safety feature on a blowgun IMI Norgren, Inc. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic-powered impact wrenches are commonly used in service and manufacturing industries These tools are used to tighten or remove bolts and nuts © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Construction of an impact wrench Chicago Pneumatic © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Parts of a pneumatic impact wrench Chicago Pneumatic © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Nutsetters are specialized impact wrenches for installing multiple fasteners Atlas Copco © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Nail drivers are used to install staples, nails, or other fasteners in wood and other materials Pneumatic models have become popular for use by general consumers, as well as by the construction industry © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic powered nail drivers use high-impact force from an air-driven piston and piston rod to quickly and easily install fasteners Caution: special care must be taken to prevent the accidental discharge of these units, which can cause injury © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic nailer at idle Chicago Pneumatic © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic nailer when actuated Chicago Pneumatic © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic rock drills are commonly used in quarries, mining, and road construction The holes bored by this equipment are used for the placement of explosive charges that break the rock along a line connecting the holes © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Pneumatic-powered gripping tools are used by robotic equipment to handle materials Robot is responsible for accurately locating and then opening and closing the gripper Gripper must provide accurate clearances and grip forces © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Grippers are used by industrial robots © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Grippers are often designed for a specific application IMI Norgren, Inc. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review Question Because of the relatively low operating pressure of pneumatic cylinders, metal _____ techniques can be used to permanently attach the barrel to the cylinder head and cap. rolling © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review Question What are the four primary types of information provided by cylinder manufacturers in their catalogs and data sheets? A. Construction materials, B. available sizes, C. pressure ratings, and D. features. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review Question List three performance factors that make piston air motors desirable in many pneumatic system applications. A. High power output, B. high starting torque, and C. accurate speed control. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review Question What determines the speed of an air motor?
The displacement of the motor and the volume of air that is metered through the unit. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review Question Name six tools that use reciprocating motors to power their operation. A. Paving breaker (or jackhammer), B. Scaling hammers, C. chipping hammers, D. riveting hammers, E. tampers, and F. rammers. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review Question An air motor should be sized to operate on what fraction of the workstation pressure to allow for the extra power needed for starting loads and unexpected overloads? 2/3 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review Question Identify the two factors that determine the impact force of a percussive, reciprocating air motor. A. Air pressure and B. piston area. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Work Performers of Pneumatic Systems

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