INDUSTRIAL PNEUMATICS Region IV Regional Training Center PNEUMATICS BASIC COURSE ON INDUSTRIAL PNEUMATICS & AUTOMATION

PNEUMATICS TOPICS 1. About Pneumatics 2. The basic pneumatic system Region IV Regional Training Center PNEUMATICS TOPICS 1. About Pneumatics 2. The basic pneumatic system 3. Control systems - Automation 4. Sequence plan

Pneumatics 1. About Pneumatics Fluid power is an applied science dealing with ways of using pressurized gas (pneumatics) or liquid (hydraulics) for doing work. Hydraulic systems use oil, which is pumped into hydraulic cylinders or hydraulic motors and made to do work. Pneumatic systems use a pressurized air, which is directed into pneumatic cylinders and made to do work.

Pneumatics are applied. .. 1. About Pneumatics Pneumatics are applied. .. Where many operations are to be performed quickly and well controlled with small force, e.g. automatic or semi-automatic operating machines 2. Where the machines given under must be quickly reset table for objects with different measurements, e.g. gluing and assembling units in the furniture manufacturing 3. Where external cleanliness is demanded, e.g. filling and packing machines in food and pharmaceutical industry.

1. About Pneumatics Advantages: Air is available everywhere. Return piping can be dispensed with. Air has a comparatively high flow speed in the piping and valves. Compressed air can be stored well in the containers. Pollution by leakage losses through untight points doesn't occur. Easy assembly with plug fasteners and flexible pipes possible. Disadvantages: Air must be treated. Leakage losses are costly because of continuous energy loss. Above 6 bar, technical safety control is necessary. Higher force is required for large cylinder diameters.

V1 X P1 = V2 X P2 = V3 X P3 = constant Pneumatics 2. The basic pneumatic system Pneumatic systems use a pressurized air, which is directed into pneumatic cylinders and made to do work. The molecules of a gas strike against each other and exert equal pressure everywhere on the wall, of the containers. lf the space is reduced the pressure rises. Provided that the temperature remains constant, the product of volume V and pressure p of a closed quantity of gas is always. the same (constant). V1 X P1 = V2 X P2 = V3 X P3 = constant The compressibility of air crucially affects the function and application of a pneumatic plant.

Pressure volume relationship for gases Pneumatics 2. The basic pneumatic system Pressure volume relationship for gases V1XP1 = V2 XP2 = V3 XP3 = constant !!

2. The basic pneumatic system Pneumatic system structure and signal flow Symbols Actuating devices Output Cylinder Final control element Control signals Processing element Processor signals Valve Input element Signal Energy supply Source - Input Compressor or

2. The basic pneumatic system Double acting cylinder Compressed Air - in 4/2-way valve (right-left actuated) The impulses are given through the manually operated control valve. Air – out Compressor

2. The basic pneumatic system 1. - Compressed air “in” - Piston moves to the right – air out 2. - 4/2-way valve actuated (right to left) and… Double acting cylinder 4/2-way valve (left-right actuated) Compressor

2. The basic pneumatic system - .. changes the direction of the flow of the compressed air Right = compressed air in Left = air out - Piston moves to the left 3. - 4/2-way valve actuated (left to right) and - …the process starts afresh

2. The basic pneumatic system

2. The basic pneumatic system

2. The basic pneumatic system

2. The basic pneumatic system

2. The basic pneumatic system Energy supply (Source) Compressed air is produced at a central place (Compressor) and with an operating pressure of 6 bar is conveyed to the consumer (Cylinder) through a pipe system. COMPRESSORS: Piston compressors b) Sliding-vane compressor c) Rotary piston compressors d) Screw compressors

2. The basic pneumatic system Treatment of compressed air – maintenance unit The air sucked from the atmosphere contains dust and moisture. In the compressor. lubricating oil residue is also carried along, so that the stored compressed air is polluted by solid matter. water and oil residue. Therefore a maintenance unit (Filter, Lubricator and Regulator) is – mostly - part of the pneumatic system.

2. The basic pneumatic system Input and control elements - Valves

2. The basic pneumatic system Input and control elements - Valves

2. The basic pneumatic system Input and control elements – Valves Sample 3 position / 4way, closed center -, -lever operated, -spring return valve A B P R P = pressure line R = return line A / B = operating lines

2. The basic pneumatic system Directional valve A: Mushroom valve In position 'a' the air flows from p to A, In position b, p is closed and the return air flows from A to R 3/2 directional valve B: The flat slide valve The flat slide valve is pre-controlled through its piston 2 and both the control pipe lines x and y, Control air at x means air on the left piston side 3 which is position 'a', and air flows from p to A and from B to R. 4/2 directional valve

2. The basic pneumatic system Directional valve C: The plate slide valve The plate slide valve has four connections and three' switching positions. It is a 4/3 directional valve, The function can be made out from the figure given on the side. It is particularly easy to operate, for which reason it is often assembled in control panels.

2. The basic pneumatic system Check valve (Non-return valve) The throttle check valve forces the air flow in one direction through the throttle, which determines the piston position and releases the air flow in the opposite direction Quick evacuating valve The air flow from p to A is free, the rubber gasket lies on right, its gasket component is bent inwards. When pressure falls at P, the air flow coming from A sets the valve on the left side and opens the path to the outlet through the exhaust silencer.

2. The basic pneumatic system Actuating devices - Output Symbol Single acting cylinder Double acting cylinder

2. The basic pneumatic system Simple controls Double-acting cylinder 2X 3/2 way valves (one valve for each direction) Double-acting cylinder 4/3 way valve (Piston blocked)

3. Control system – Automation Pneumatics 3. Control system – Automation A: Speed regulation 1. Discharge air throttling The throttles regulate the air passage and thereby the piston speed. 2. Intake air throttling Only the shifted return check valve is actuated so that intake air in each case flows through the throttle valves.

3. Control system – Automation Pneumatics 3. Control system – Automation B: Will-, Path- and Time – dependent control 1. Will-dependent control - the impulses for reversing the main control valve 1.1 are given through the manually or pedal-operated pre-control valves

3. Control system – Automation Pneumatics 3. Control system – Automation Will-dependent control

3. Control system – Automation Pneumatics 3. Control system – Automation 2. Path-dependent control the same basic construction is applied. Instead of manual or pedal operation, pulsings are sent by the forward or backward moving piston rod or by its attached machine part

3. Control system – Automation Pneumatics 3. Control system – Automation Path-dependent control

3. Control system – Automation Pneumatics 3. Control system – Automation 3. The time-dependent control has in addition two throttle check valves, with which a sequence delay can be set up.

3. Control system – Automation Pneumatics 3. Control system – Automation The time-dependent control

3. Control system – Automation Pneumatics 3. Control system – Automation Sequence controls of two cylinders 1. The path-dependent sequence control is achieved by a negative impulse. It denotes that in the main control valve 1.1, both sides x and y remain under pressure, and the actuating piston shifts towards the side which is deaerated through one of the two pre-control valves 1.2 or 1.3.

3. Control system – Automation Pneumatics 3. Control system – Automation The path-dependent sequence control (negative impulse)

3. Control system – Automation Pneumatics 3. Control system – Automation 2. Pressure-dependent sequence control -the second cylinder comes into action only when the first one has come into full operation. Valve 1.1 moves- in position 'b. by hand operation. The cylinder 1.0 moves out till it is stopped and the air pressure is, built up as far as to overcome the pressure limiting valve 1.2 and thus bring to operation the cylinder with a speed adjusted on the throttle check valve 2.3. After switching over from 1.1 to 'a. the cylinder 2.0 moves back first and in this end position the pressure rises so much that through the valve 1.~ cylinder 1.0 is also brought back at an adjusted speed by 1.2.

3. Control system – Automation Pneumatics 3. Control system – Automation 3. Alternating control In an alternating control with lag the cylinder with adjustable speed shall be driven out, then remain an adjustable time in rest position and return in quick motion. After 1.4 has been brought to position b the cylinder 1.0 moves out due to regulated discharge air in 1.3.ln end moves out due to regulated discharge air in 1.3. In end position 1.6 is operated, which causes cylinder 1.9 via throttle check valve 1.8 to drive out delayed. At its end the cylinder switches 1.7 to b, so that control air 1.1 is switched to b. Through the throttle check valve 1.3 cylinder 1.0 will return quickly whereby cylinder air escapes through a quick deaerating valve and exhaust absorber. In the end position of the cylinder 1.0 the valve is again moved in position a through 1.5 and the working cycle starts again.

3. Control system – Automation Pneumatics 3. Control system – Automation Alternating control

Pneumatics 4. Sequence plan The red line indicates the cylinder motion - piston “in” / ”out” - time-depending 0 1 2 3 seconds Time Cylinder 1 (Piston “out”) (Piston “in”) The point represent the operating of a valve

Pneumatics 4. Sequence plan 0 1 2 3 Cylinder 1 Time

Pneumatics 4. Sequence plan 0 1 2 3 Cylinder 1 Time

Pneumatics 4. Sequence plan 4 5 6 7 Cylinder 1 Time

Pneumatics 4. Sequence plan 4 5 6 7 Cylinder 1 Time

Pneumatics 4. Sequence plan 8 9 10 11 Cylinder 1 Time

Pneumatics 4. Sequence plan 8 9 10 11 Cylinder 1 Time

4. Sequence plan SAMPLE The points represents the operating of a valve Pneumatics SAMPLE 4. Sequence plan The points represents the operating of a valve the arrows pointing out from these indicate cylinder motions effected by the valve.

Description of the sequence Pneumatics 4. Sequence plan Description of the sequence SEQUENCE: Cylinder 1.0 in extended condition after 2 seconds operates the valve 2.10 and thus carries out the motion of cylinder 2.0. Cylinder 2.0 actuates valve 3.2., allowing the control air to reach the control valves and the cylinders 3.0,4.0 and 5.0 move out. Cylinder 5.0 operates valve 1.3 and the cylinder 1.0 moves back. Cylinder 5.0 actuates valve 3.3 and as a result cylinder 2.0, 3.0, 4.0 and 5.0 (after 0.5 seconds) move back (return). Cylinder 2.0 while returning actuates valve 6.2 and cylinder 6.0 moves out-at the end valve 6.3 gets operated and cylinder 6.0 moves back. As a result cylinder 6.0 actuates valve 1.2 and sets cylinder 1.0 in motion. The sequence starts again.