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Cascade Control Method

Cascade Control Method. Introduction. Cascade system uses signal cut out by means of reversing valves Air supplied to switches are from reversing valves Reversing valves are control by limit switches. Group 1. Group 2. Change to group 1. Change to group 2. Design of Cascade.

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Cascade Control Method

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  1. Cascade Control Method ms 4.22 Cascade Control Method/Tieh SF

  2. Introduction • Cascade system uses signal cut out by means of reversing valves • Air supplied to switches are from reversing valves • Reversing valves are control by limit switches ms 4.22 Cascade Control Method/Tieh SF

  3. Group 1 Group 2 Change to group 1 Change to group 2 Design of Cascade • Only one output line is pressurized at any one time 2 Groups & 1 Reversing valve ms 4.22 Cascade Control Method/Tieh SF

  4. 3 Groups & 2 Reversing valves Group 1 Group 2 Group 3 Reversing Valve 1 Reversing Valve 2 Design of Cascade ms 4.22 Cascade Control Method/Tieh SF

  5. 4 Groups & 3 Reversing valves Group 1 Group 2 Group 3 Group 4 Reversing Valve 1 Reversing Valve 2 Reversing Valve 3 Design of Cascade ms 4.22 Cascade Control Method/Tieh SF

  6. Controlling the reversing valves with limit switches Group 1 Group 2 Group 3 Group 4 ms 4.22 Cascade Control Method/Tieh SF

  7. Procedure for constructing a Cascade system 1) Define the sequence of motion 2) Divide them into minimum group 3) Supply lines 4) Reversing valves 5) Limit switches a1 a0 b0 A + B + B - A - C + C - b1 c1 c0 I II III ms 4.22 Cascade Control Method/Tieh SF

  8. Transposition into circuit 1) Limit switches/valves which cause change over of groups are drawn below the supply lines 2) Limit switches within the same group are drawn above the supply lines 3) Include an “AND” valve when a cylinder extend more than one time (eg. A + B + B - A - C + A + A - C - ) 4) Auxiliary conditions and additional interlocks are added only after the basic sequence design has finished a1 a0 b0 A + B + B - A - C + C - b1 c1 c0 I II III ms 4.22 Cascade Control Method/Tieh SF

  9. Auto-start and auto stop modes ms 4.22 Cascade Control Method/Tieh SF

  10. Advantages of cascade system • Circuit can be designed and checked quickly • Easier to trace faults • System ensure that signals are inherently of sufficient duration to perform their require tasks ms 4.22 Cascade Control Method/Tieh SF

  11. Disadvantages of cascade system • May not yield the simplest solution for certain circuits • the pressure drop becomes significant as the number of stages increase • great care to be exercised when limit switch is depressed by external source ms 4.22 Cascade Control Method/Tieh SF

  12. Example (Punching fixture) ms 4.22 Cascade Control Method/Tieh SF

  13. 0 1 Cylinder 1.0 (A) 0 1 Cylinder 2.0 (B) 0 1 Cylinder 3.0 (C) 0 1 Cylinder 4.0 (D) Example (Punching fixture) B- A+ B+ C+ D+ C- A- D- ms 4.22 Cascade Control Method/Tieh SF

  14. Example (Punching fixture circuit ) B- A+ B+ C+ D+ C- A- D- ms 4.22 Cascade Control Method/Tieh SF

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