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

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1 Chapter 17 Work Performers of Pneumatic Systems Cylinders, Motors, and Other Devices 1

2 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. 3 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. 4 2

3 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. 5 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. 6 3

4 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. 7 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. 8 4

5 Pneumatic Cylinder Construction Typical pneumatic cylinders Parker Hannifin Goodheart-Willcox Co., Inc. 9 Pneumatic Cylinder Construction 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. 10 5

6 Pneumatic Cylinder Construction Basic pneumatic cylinder construction IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 11 Pneumatic Cylinder Construction 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. 12 6

7 Pneumatic Cylinder Construction Resilient seals prevent both internal and external leaks IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 13 Pneumatic Cylinder Construction 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. 14 7

8 Pneumatic Cylinder Construction Typical, single-acting cylinder IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 15 Pneumatic Cylinder Construction 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. 16 8

9 Pneumatic Cylinder Construction Rolled-metal ends on a cylinder Parker Hannifin Goodheart-Willcox Co., Inc. 17 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. 18 9

10 Pneumatic Cylinder Sizing 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. 19 Pneumatic Cylinder Sizing 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

11 Pneumatic Cylinder Sizing 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. 21 Pneumatic Cylinder Sizing 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

12 Pneumatic Rotary Motors Typical rotary motors Atlas Copco Goodheart-Willcox Co., Inc. 23 Pneumatic Rotary Motors Pneumatic motors are used to power: Many large stationary machines A large variety of portable hand tools These motors range in size from fractionalhorsepower units to motors producing over 50 horsepower Goodheart-Willcox Co., Inc

13 Pneumatic Rotary Motors 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. 25 Pneumatic Rotary Motors Vane motors can be found in hand tools and large, stationary installations Atlas Copco Goodheart-Willcox Co., Inc

14 Pneumatic Rotary Motors Operation of a vane motor Goodheart-Willcox Co., Inc. 27 Pneumatic Rotary Motors Operation of a vane motor Goodheart-Willcox Co., Inc

15 Pneumatic Rotary Motors Operation of a vane motor Goodheart-Willcox Co., Inc. 29 Pneumatic Rotary Motors Operation of a vane motor Goodheart-Willcox Co., Inc

16 Pneumatic Rotary Motors 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. 31 Pneumatic Rotary Motors Parts of an axial-piston motor Goodheart-Willcox Co., Inc

17 Pneumatic Rotary Motors Parts of an axial-piston motor Goodheart-Willcox Co., Inc. 33 Pneumatic Rotary Motors 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

18 Pneumatic Rotary Motors Turbine air motor Atlas Copco Goodheart-Willcox Co., Inc. 35 Pneumatic Rotary Motors 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

19 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. 37 Pneumatic Reciprocating Motors Total input force of a percussion-type reciprocating motor is determined by: System air pressure Area of the piston Goodheart-Willcox Co., Inc

20 Pneumatic Reciprocating Motors 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. 39 Pneumatic Reciprocating Motors Example of a reciprocating motor Atlas Copco Goodheart-Willcox Co., Inc

21 Pneumatic Reciprocating Motors 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. 41 Pneumatic Reciprocating Motors Chipping hammers are used in foundries Atlas Copco Goodheart-Willcox Co., Inc

22 Pneumatic Reciprocating Motors Using a tamper on a casting mold Badger Iron Works, Inc. Goodheart-Willcox Co., Inc. 43 Pneumatic Reciprocating Motors 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

23 Other Pneumatic-Powered 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. 45 Other Pneumatic-Powered Insecticide is usually sprayed USDA Goodheart-Willcox Co., Inc

24 Other Pneumatic-Powered 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. 47 Other Pneumatic-Powered Agitation is used in sewage treatment Goodheart-Willcox Co., Inc

25 Other Pneumatic-Powered 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. 49 Other Pneumatic-Powered Nozzle designs Goodheart-Willcox Co., Inc

26 Other Pneumatic-Powered A blowgun is a simple example of a nozzle IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 51 Other Pneumatic-Powered 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

27 Other Pneumatic-Powered Bleed-off safety feature on a blowgun IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 53 Other Pneumatic-Powered 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

28 Other Pneumatic-Powered Construction of an impact wrench Chicago Pneumatic Goodheart-Willcox Co., Inc. 55 Other Pneumatic-Powered Parts of a pneumatic impact wrench Chicago Pneumatic Goodheart-Willcox Co., Inc

29 Other Pneumatic-Powered Nutsetters are specialized impact wrenches for installing multiple fasteners Atlas Copco Goodheart-Willcox Co., Inc. 57 Other Pneumatic-Powered 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

30 Other Pneumatic-Powered Typical pneumatic nail driver Goodheart-Willcox Co., Inc. 59 Other Pneumatic-Powered Pneumatic powered nail drivers use highimpact 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

31 Other Pneumatic-Powered Pneumatic nailer at idle Chicago Pneumatic Goodheart-Willcox Co., Inc. 61 Other Pneumatic-Powered Pneumatic nailer when actuated Chicago Pneumatic Goodheart-Willcox Co., Inc

32 Other Pneumatic-Powered 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. 63 Other Pneumatic-Powered Pneumatic rock drill Atlas Copco Goodheart-Willcox Co., Inc

33 Other Pneumatic-Powered 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. 65 Other Pneumatic-Powered Grippers are used by industrial robots Goodheart-Willcox Co., Inc

34 Other Pneumatic-Powered Grippers are often designed for a specific application IMI Norgren, Inc. Goodheart-Willcox Co., Inc. 67 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

35 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. 69 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

36 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. 71 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

37 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. 73 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