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IENG 475 - Lecture 12

IENG 475 - Lecture 12. Relay and Pneumatic (Fluid) Control Logic. Assignment. Assignment Begin HW 04. Do this in teams of 1 – 2 persons. Complete Product Design & Cut Personal Parts Finish programming verification & cut individual parts – by end of lab 24 APR .

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IENG 475 - Lecture 12

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  1. IENG 475 - Lecture 12 Relay and Pneumatic (Fluid) Control Logic IENG 475: Computer-Controlled Manufacturing Systems

  2. Assignment • Assignment • Begin HW 04. Do this in teams of 1 – 2 persons. • Complete Product Design & Cut Personal Parts • Finish programming verification & cut individual parts – by end of lab 24 APR. • Begin documentation of team project, ASAP. Most of the routing information can be pulled from your MasterCAM files, and you can pull images from the SolidWorks files. • Remember to collect timing data as you go! IENG 475: Computer-Controlled Manufacturing Systems

  3. Relays (Switches) • Specification: • Poles & Throws • Making (N.O.) / Breaking (N.C.) • Latching (toggle) / Non-latching (momentary) • Transfer between low power logic controls and high power energy controls • Coil Nomenclature: • “relay” (< 10 A) • “power relay” (10 - 30 A) • “contactor” (> 30 A) • “starters” (Overload protection, thermal) • Potential problem: “contact bounce” IENG 475: Computer-Controlled Manufacturing Systems

  4. NC COM NO NC NO COM NC COM NO Switch Nomenclature • Poles – number of individual complete circuits switched at a time • Throws – number of positions for each pole • Normally Open / Normally Closed – stable position (if there is one) • Latching / Momentary – stays in position / returns to normal position Single Pole, Double Throw, Latching Single Pole, Single Throw, Normally Closed, Momentary Single Pole, Single Throw, Normally Open, Latching SPDT – Latching (Toggle) SPST - NO Latching SPST – NC Momentary Double Pole, Single Throw, Normally Open, Latching Double Pole, Single Throw, Normally Open, Momentary Double Pole, Double Throw, Latching DPST - NO Latching DPST – NO Momentary DPDT – Latching (Toggle) IENG 475: Computer-Controlled Manufacturing Systems

  5. a b c a c b a c Wire Logic • Review: Current flows from source to ground • “AND” (•): • c = a•b • “OR” (+): • c = a + b • “NOT” ( ¯ ): • c = a IENG 475: Computer-Controlled Manufacturing Systems

  6. e a b c d e Wire Logic • Example: Missile engine (e) should start only when the President (a) orders it fired and both range officers (b and c) concur with the order. Once fired, the engine should stay on unless the self-destruct (d) is activated. • e = [ ( a • b • c ) + e ] • d IENG 475: Computer-Controlled Manufacturing Systems

  7. Pneumatics • Why use Pneumatic Controls? • Can withstand stalling without damage • Explosion proof • Generate little heat (at point of operation) • No shock hazard • Can operate underwater with minimal problems • Can obtain high speeds • Can obtain medium sized forces • Switching Sense: • Normally Not-Passing / Normally Passing • Compare with N.O. / N.C. for electrical switching IENG 475: Computer-Controlled Manufacturing Systems

  8. System View • Components of a shop pneumatic system: • compressor • receiver • main line • branch line • outlet IENG 475: Computer-Controlled Manufacturing Systems

  9. ISO Symbology • Air flow paths are shown as solid lines. • Valve ports are shown on the outside of one of the position squares, denoting the normal position. • Flow paths within the valves are shown as arrows. • Terminations are shown as lines with a short “cap” line perpendicular to the end (T). • Exhaust ports are shown as lines terminated with a “outward” pointing triangle. IENG 475: Computer-Controlled Manufacturing Systems

  10. Signal / Control Valves • Signal & Control Valves: • Number of ports may be counted from the lines exiting the normal position square • Number of squares is the number of positions • Example: 3/2 manually actuated signal valve • Function is evident by shifting position squares IENG 475: Computer-Controlled Manufacturing Systems

  11. Valve Actuation • General (Manual) Actuation • Mechanical Actuation • Solenoid Actuation • Air Actuation IENG 475: Computer-Controlled Manufacturing Systems

  12. Logic Valves • (OR gate) Shuttle Valve • (AND gate) Two Pressure Valve IENG 475: Computer-Controlled Manufacturing Systems

  13. Dual Acting Cylinder • To extend the cylinder,air flows in the left side, exhausting the right side... • To retract the cylinder,air enters on the right side, exhausting the left side. IENG 475: Computer-Controlled Manufacturing Systems

  14. ISO Pneumatic Diagrams • From top to bottom, component layers are: • Actuators • Speed Controls* • Control Valves • Logic Valves • Signal Valves • Pressure Supply * not discussed in handout IENG 475: Computer-Controlled Manufacturing Systems

  15. Questions & Issues • Lab: • Computer-Aided Milling/3-D Printer/Laser Operations • Finish CAD/CAM work • Personal design parts (by lab this week, in team folder) • Lathe/3-D Print part (at least 1 per team, in team folder) • Mill Part (at least 1 per team, in team folder) • Laser Engraver (at least 1 per team, in team folder) • Drill Part (1 per team, organize with team) • Perform CNC Milling & Turning, Engraving, Drilling • All parts – timing! IENG 475: Computer-Controlled Manufacturing Systems

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