week 6 2_design_of_pneumatic_circuit

Based on :

◦ Understanding the problem by considering type and quantity of components

◦ Number of process*

* Each process is represented by one cylinder (actuator)

Understand the problem step by step:

◦ Identify type of cylinder

◦ Identify the right control valve for selected cylinder

◦ Identify methods to start the operation

◦ Identify methods to stop the operation

◦ Identify other parameters (if needed)

SINGLE ACTUATOR CIRCUITS

Actuated directly via mechanical valve, without intermediate switching

Limits: 1) Piston diameter < 40 mm 2) Valve with connection size < 1/4” If not mentioned, use indirect control Example: A single cylinder of 25 mm in diameter is to clamp a

component when a push button is pressed. As push button is activated, the cylinder is to remain in the clamp position. If the push button is released, the clamp is to retract.

Solution: ◦ Identify type of cylinder Single acting with spring return ◦ Identify right control valve for selected cylinder 3/2 way valve (for single acting) ◦ Identify methods to start the operation Push button (3/2 way with spring) ◦ Identify methods to stop the operation Push button (release the start button) ◦ Identify others parameter (if needed) NIL

Used when the force should prove too high for manual actuation of valve (for large piston diameter) Signal is generated via smaller valve Example: A single cylinder with a large piston diameter, is to

clamp a workpiece following actuation of a push button. The cylinder is retract once the push button is released.

Solution: ◦ Identify type of cylinder Single acting with spring return ◦ Identify right control valve for selected cylinder 3/2 way valve (for single acting) ◦ Identify methods to start the operation Push button (3/2 way with spring) activate

control valve ◦ Identify methods to stop the operation Push button (release the start button) ◦ Identify others parameter (if needed) NIL

Example

◦ A double acting cylinder is to advance if one of two push buttons is operated. If the push button is released, the cylinder is to retract.

Example

◦ The piston rod of DAC is to advance when the 3/2-way roller lever valve AND the push button of 3/2-way valve are actuated. If either of these are released, then the cylinder will return to its initial position.

Example ◦ Clamping of a drilling machine starts when one of

two push buttons is pressed and it is released when the third push button is pressed. ◦ Parameters There is no clamping if the workpiece is not in the

position. Clamping device cannot be opened during the

drilling in operation. Clamping process must be performed slowly. Clamp opening must be performed rapidly.

F=0

4 2

5

1

31 1

2

1 1

2

2

1 3

WS

2

1 3

2

1 3

1 1

2

2

1 3

2

1 3

DS

F=0

2

1 3

DSWS

35%

1

2

3

Start A Start B

St op Drill Sensor

Workpiece Sensor

DRILL M/CCLAMP M/C