1 / 74

Chapter 17

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.

love
Download Presentation

Chapter 17

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 17 Work Performers ofPneumatic Systems Cylinders, Motors, and Other Devices

  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. Permission granted to reproduce for educational use only.

  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. Permission granted to reproduce for educational use only.

  4. 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 Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  6. 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 Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  8. Pneumatic Cylinder Construction • Typical pneumatic cylinders Parker Hannifin Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  10. Pneumatic Cylinder Construction • Basic pneumatic cylinder construction IMI Norgren, Inc. Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  12. Pneumatic Cylinder Construction • Resilient seals prevent both internal and external leaks IMI Norgren, Inc. Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  14. Pneumatic Cylinder Construction • Typical, single-acting cylinder IMI Norgren, Inc. Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  16. Pneumatic Cylinder Construction • Rolled-metal ends on a cylinder Parker Hannifin Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  18. 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 Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  20. 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 Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  22. Pneumatic Rotary Motors • Typical rotary motors Atlas Copco Permission granted to reproduce for educational use only.

  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 fractional-horsepower units to motors producing over 50 horsepower Permission granted to reproduce for educational use only.

  24. 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 Permission granted to reproduce for educational use only.

  25. Pneumatic Rotary Motors • Vane motors can be found in hand tools and large, stationary installations Atlas Copco Permission granted to reproduce for educational use only.

  26. Pneumatic Rotary Motors • Operation of a vane motor Permission granted to reproduce for educational use only.

  27. Pneumatic Rotary Motors • Operation of a vane motor Permission granted to reproduce for educational use only.

  28. Pneumatic Rotary Motors • Operation of a vane motor Permission granted to reproduce for educational use only.

  29. Pneumatic Rotary Motors • Operation of a vane motor Permission granted to reproduce for educational use only.

  30. 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 Permission granted to reproduce for educational use only.

  31. Pneumatic Rotary Motors • Parts of an axial-piston motor Permission granted to reproduce for educational use only.

  32. Pneumatic Rotary Motors • Parts of an axial-piston motor Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  34. Pneumatic Rotary Motors • Turbine air motor Atlas Copco Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  36. Pneumatic Reciprocating Motors • Pneumatic reciprocating motorsuse 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 Permission granted to reproduce for educational use only.

  37. Pneumatic Reciprocating Motors • Total input force of a percussion-type reciprocating motor is determined by: • System air pressure • Area of the piston Permission granted to reproduce for educational use only.

  38. Pneumatic Reciprocating Motors • The paving breakeris 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 Permission granted to reproduce for educational use only.

  39. Pneumatic Reciprocating Motors • Example of a reciprocating motor Atlas Copco Permission granted to reproduce for educational use only.

  40. 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 Permission granted to reproduce for educational use only.

  41. Pneumatic Reciprocating Motors • Chipping hammers are used in foundries Atlas Copco Permission granted to reproduce for educational use only.

  42. Using a tamper on a casting mold Pneumatic Reciprocating Motors Badger Iron Works, Inc. Permission granted to reproduce for educational use only.

  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 Permission granted to reproduce for educational use only.

  44. 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 Permission granted to reproduce for educational use only.

  45. Other Pneumatic-Powered Functions and Equipment • Insecticide is usually sprayed USDA Permission granted to reproduce for educational use only.

  46. Other Pneumatic-Powered Functions and Equipment • Compressed air is used to agitate material • Assure proper mixing of liquids • Prevent the settling of solid materials in a suspension • Provide oxygenation Permission granted to reproduce for educational use only.

  47. Other Pneumatic-Powered Functions and Equipment • Agitation is used in sewage treatment Permission granted to reproduce for educational use only.

  48. Other Pneumatic-Powered Functions and Equipment • 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 Permission granted to reproduce for educational use only.

  49. Other Pneumatic-Powered Functions and Equipment • Nozzle designs Permission granted to reproduce for educational use only.

More Related