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Authorised By
SANTOSH BHARADWAJ REDDY
Email: [email protected]
Engineeringpapers.blogspot.com
More Papers and Presentations available on above site
System with shuttle valve - (OR).
The shuttle valve provides pressure at the outlet port, when pressure is applied to one or more ofthe valve's inlet ports, in this sense it has the function as an OR logic element for pneumaticsystems.
When the control circuit of a pneumatic system incorporates a shuttle valve it (the pneumaticsystem) can be controlled by two independant control signals. These control signals can beinitiated from two separate and independent stations.
Typical application of shuttle valves in practice is the control systems of textile, packing andwoodworking machines, as well as in processing and assembly lines.
Component picture
The picture below shows a Bosch component, related to the material presented in this tutorial.
Outlet port 2(A)
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Inlet port 1(E1) Shuttle valve housing Inlet port 1(E2)
Construction of the component
In general, the figure below shows a cross section of how the component is constructed.
Housing Outlet port 2(A) Inlet port 1(E2)
Inlet port 1(E1) Free spool
Standard graphical symbol
The graphical symbol of the components, used in schematics of pneumatic systems, are shownbelow. They are standardized in DIN ISO 1219.
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Basic technical specifications
The basic technical specifications of the component are as follows:
nominal size M5 to G1 ports
nominal flow rate qv [ l/min ];
minimum acceptablepressure
p e, min[ bar ];
rated pressure pe[ bar ];
How the component works.
System with shuttle valve-(OR). Frame 1 of 5
When the directional control valves 1.1 and 1.2 are in initial position, as shown in the figureabove, the right control port of the 5/2 directional control valve 1.5 is vented trough the shuttlevalve 1.3. The whole system is also in initial position.
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System with shuttle valve-(OR). Frame 2 of 5
When the 3/2 valve 1.1 is switched overONLY, pneumatic control signal is fed to the 5/2 valve.The spool of the latter is shifted to the position as shown in the figure above. The piston area ofthe cylinder is connected to the pressure line and the piston moves foreword, until the piston rodswitches-over the pneumatic limit switch 1.4.
System with shuttle valve-(OR). Frame 3 of 5
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When the 3/2 valve 1.2 is switched overONLY the effect over the system is the same. Pneumaticcontrol signal is fed to the 5/2 valve. The spool of the latter is shifted to the position as shown inthe figure above. The piston area of the cylinder is connected to the pressure line and the pistonmoves foreword, until the piston rod switches-over the pneumatic limit switch 1.4.
System with shuttle valve-(OR). Frame 4 of 5
When both valves 1.1 and 1.2 are switched overSIMULTANEOUSLY the same effect over thesystem will be achieved - i.e. forward motion of the piston rod until it switches-over the pneumaticlimit switch 1.4. Note, that pneumatic control signal is fed to both control ports of valve 1.5.
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System with shuttle valve-(OR). Frame 5 of 5
When any of the 3/2 directional control valves 1.1 or/and 1.2 are switched back to initial position,the right control port of valve 1.5 is vented. The pressure on the left control port shifts the spool ofvalve 1.5 to the position shown on the figure above. Now the annular area of the piston isconnected to the pressure line and the piston initiates a reverse motion.
5/2 directional control valve,pneumatically operated
Doubleacting
cylinder
3/2 directional control valve,mechanically operated with
roller
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Shuttlevalve
Source of energy Air-service unit 3/2 directional control valve,mechanically operated
Hand slidevalve
The shuttle valve will provide pressure at the outlet port, when pressure isapplied to anyone of the inlet ports.
When a shuttle valve is used as a basis for the control logic in a pneumatic systems, theshuttle valve can be controlled by two independent control button(s).
When two control signals are applied sequentially to initialize the pneumatic system , thesecond signal would be ignored.
System with twin-pressure valve - (AND)
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The twin-pressure valve provides pressure at the outlet port when pressure is simultaneouslyapplied to both of the valve's inlet ports. In this sense it is a logical "AND" component forpneumatic systems.
In the case when two different levels of pressure are applied at the inlet ports, the lower levelof pressure comes through to output port.
Typical application of shuttle valves in the practice is the control systems of textile, packing andwoodworking machines, as well as in processing and assembly lines.
Component picture
The picture below shows a Bosch component, related to the material presented in this tutorial.
Connection screws Outlet port 2(A) Connection screws
Inlet port 1(E1) Twin-pressure valve housing Inlet port 1(E2)
Construction of the component
In general, the figure below shows a cross section of how the component is constructed.
Housing 2(A) Outlet port
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1(E1) Inlet port Free spool Inlet port 1(E2)
Standard graphical symbol
The graphical symbol of the components, used in schematics of pneumatic systems, are shownbelow. They are standardized in DIN ISO 1219.
Basic technical specifications
The basic technical specifications of the component are as follows:
nominal size M5 to G1/4 port;
nominal flow rate qv [ l/min ];
minimum acceptablepressure
p e, min[ bar ];
rated pressure pe[ bar ];
How the component works.
System with twin-pressure valve - (AND). Frame 1 of 5
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When the directional control valves 1.1 and 1.2 are in initial position, as shown in the figureabove, the right control port of the 5/2 directional control valve 1.5 is vented trough the twin-
pressure valve 1.3. The whole system is also in initial position.
System with twin-pressure valve - (AND). Frame 2 of 5
By switching the 3/2 directional control valve 1.1 over, the pressure is applied to the twin-pressurevalve as shown on the figure above. The spool of the latter is shifted and closes the connection tothe control port of valve 1.5.
System with twin-pressure valve - (AND). Frame 3 of 5
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Similarly, by switching the 3/2 directional control valve 1.2 over, the pressure is applied to thetwin-pressure valve as shown on the figure above. The spool of the latter is shifted and againcloses the connection to the control port of valve 1.5.
System with twin-pressure valve - (AND). Frame 4 of 5
When both valves 1.1 and 1.2 are switched over simultaneously, pressure is provided to bothports of the twin-pressure valve 1.3. The spool of the latter is shifted to a mid position as shownon the figure above. Consequently, pressure control signal is fed to the right control port of 5/2directional control valve 1.5. This shifts the spool of the latter as shown on the figure. As a result,the piston area of the cylinder is connected to the pressure line and the piston starts movingforeword.
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System with twin-pressure valve - (AND). Frame 5 of 5
The reverse motion of the cylinder piston is achieved by switching the valve 1.5 over with apneumatic control signal from valve 1.4. The control signal is generated when the cam of thepiston rod switches over vale `.4 as shown on the figure.\
5/2 directional control valve,pneumatically operated
Double actingcylinder
3/2 directional control valve,mechanically operated
with roller
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Twin-pressurevalve
Source of energy Air-service unit Hand slide
valve
3/2 directional
control valve,mechanically operated
System with quick exhaust valve
Quick-exhaust valves are components which provide a means to increase the speed a cylinder piston. Thisis achieved by providing the vent line of the cylinder with and exhaust port, having larger cross-section, than
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the line itself. As a result, the resistance of the air-flow is significantly decreased, hence the cylinder pistoncan move faster.
Quick-exhaust valves are connected to pressure release lines directly on the cylinder or close to it. Theincrease of the speed depends on the size of the cross-section of the valve's outlet. It should be noted, thatdesired speeds of the cylinder piston motion cannot be precisely adjusted.
Typical applications can be found in automated tool magazines supporting various operations, such asboring, cutting, forging.
Component picture
The picture below shows a Bosch component, related to the material presented in this tutorial.
Pressure inlet port Outlet port
Housing Exhaust port
Construction of the component
In general, the figure below shows a cross section of how the component is constructed.
Housing 2(A) Outlet port
1(P) Pressure inlet port Free spool Exhaust port 3(R)
Standard graphical symbol
The graphical symbol of the components, used in schematics of pneumatic systems, are shownbelow. They are standardized in DIN ISO 1219.
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Basic technical specifications
The basic technical specifications of the component are as follows:
nominal flow rate qv [ l/min ]
minimum admitted pressure pe [ bar ]
rated pressure pe [ bar ]
connection threads G 1/4 to G1/2
How the system worksSystem with quick exhaust valve. Frame 1 of 2
When switching the directional control valve 1.1 to position as shown on the figure above, thecylinder piston will initiate a reverse motion. This speed of this motion will be determined by theair pressure supply of the air service unit.
System with quick exhaust valve. Frame 2 of 2
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When switching the directional control valve 1.1 to the position shown on the figure cylinderpiston will start moving forward. The cover port is vented through the quick exhaust valve. In thiscase the speed is determined by the size of the exhaust port of the quick exhaust valve.
Doubleacting
3/2 directionalcontrol valve,
Quickexhaust
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cylinder mechanically operated valve
One wayflow
controlvalve
Sourceof energy
Air-serviceunit
Hand slide valve 5/2 directionalcontrol valve,
electrically operated
System with adjustable length of the cylinder stroke
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Another typical solution in pneumatic applications is the system with adjustable stroke of thecylinder. Here the piston rod of the pneumatic cylinder moves forward until it actuates a limitvalve, which will reverse the movement of the cylinder piston. The distance between the rod-endhead of the cylinder and the limit valve determines the stroke length of the cylinder rod.
Such pneumatic systems are used in pneumatic manipulators and automatic production lines.
System with adjustable stroke of the cylinder. Frame 1 of 4
When the manuallyoperated directional control valve 1.1 is not pressed the cylinder piston staysretracted, as shown in the figure above.
System with adjustable stroke of the cylinder. Frame 2 of 4
When the manually-operated directional valve 1.1 is pressed and shortly after released the 5/2directional control valve 1.6 is switched over to the position, shown on the figure. As a result thepiston of the cylinder starts moving forward.
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System with adjustable stroke of the cylinder. Frame 3 of 4
The pilot valve 1.5 is switched over as soon as the piston rod reaches the roller, attached to the
valve's spool. The signal of the pilot valve 1.5 shifts the spool of the 5/2 directional control 1.6 tothe right - position "12" as show on the figure. Consequently the piston moves backwards. Thedistance between the piston cover of the cylinder and the pilot valve 1.5 determines thestroke length of the cylinder rod.
System with adjustable stroke of the the cylinder. Frame 4 of 4
When the piston reaches the cylinder bottom it switches over the pilot valve 1.4 on and stops. Bythis means the system is ready to perform a subsequent stroke, as soon as the button of valve1.1 is pressed and released.
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Doubleacting
cylinder
5/2 directionalcontrol valve,
pneumatically operated
Shuttlevalve
Sourceof energy
Air-serviceunit
3/2 directionalcontrol valve,
mechanically operated
3/2 directionalcontrol valve,
mechanically operatedwith roller
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System with two forward speeds of the cylinder piston
This tutorial describes a typical pneumatic solution, which provides a 2-stage speed control ofcylinder piston during the foreword motion of the piston. In the initial stage, when the piston is atthe cap-end of the cylinder, the speed is fast. The transition to the slow speed is made at thepoint when the rod actuates a 3/2 limit valve.
Such pneumatic systems are used in machine tools, pneumatic manipulators and automatedassembly lines.
System with two speeds forward. Frame 1 of 4
When the 5/2 directional control valve 1.1 is switched to the position shown on the figure, thepiston area is connected to the atmosphere and the annulus area is connected to the pressure
line. The pressure presses the piston to the cylinder bottom.
System with two speeds forward Frame 2 of 4
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When the 5/2 directional control valve 1.1 is switched to position as shown on the figure, thepressure line is connected to the piston area of the cylinder. The air from the annulus area isvented through the 3/2 control valve 1.6 and one-way flow control valve 1.5. This allows a highspeed forward for the piston.
System with two speeds forward Frame 3 of 4
When the cam of the piston rod switches the pilot valve 1.3 over, a pneumatic control signal is fedto the left control port of valve 1.6. The spool of the latter is shifted to the position. shown on thefigure. This closes the vent line, directly connected to the atmosphere. The only way the annulusarea can be vent is through the one-way flow control valve 1.5. The setting of the latterdetermines the speed of the piston.
System with two speeds forward. Frame 4 of 4
When the 5/2 directional control valve 1.1 is switched to position, shown on the figure, thepressure line is connected through the one-way flow control valve 1.5 to the annulus area of the
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piston. The piston area is now connected to the atmosphere and the piston moves backwards ata high speed.
Doubleacting
cylinder
5/2 directionalcontrol valve,
pneumatically operated
Shuttle
valve
Sourceof energy
Air-serviceunit
3/2 directionalcontrol valve,
mechanically operated
3/2 directionalcontrol valve,
mechanically operatedwith roller
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System with two forward speeds of the cylinder piston
This tutorial describes a typical pneumatic solution, which provides a 2-stage speed control ofcylinder piston during the foreword motion of the piston. In the initial stage, when the piston is atthe cap-end of the cylinder, the speed is fast. The transition to the slow speed is made at thepoint when the rod actuates a 3/2 limit valve.
How the system works...
System with two speeds forward. Frame 1 of 4
When the 5/2 directional control valve 1.1 is switched to the position shown on the figure, thepiston area is connected to the atmosphere and the annulus area is connected to the pressureline. The pressure presses the piston to the cylinder bottom.
System with two speeds forward Frame 2 of 4
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When the 5/2 directional control valve 1.1 is switched to position as shown on the figure, thepressure line is connected to the piston area of the cylinder. The air from the annulus area isvented through the 3/2 control valve 1.6 and one-way flow control valve 1.5. This allows a highspeed forward for the piston.
System with two speeds forward Frame 3 of 4
When the cam of the piston rod switches the pilot valve 1.3 over, a pneumatic control signal is fedto the left control port of valve 1.6. The spool of the latter is shifted to the position. shown on thefigure. This closes the vent line, directly connected to the atmosphere. The only way the annulusarea can be vent is through the one-way flow control valve 1.5. The setting of the latterdetermines the speed of the piston.
System with two speeds forward. Frame 4 of 4
When the 5/2 directional control valve 1.1 is switched to position, shown on the figure, thepressure line is connected through the one-way flow control valve 1.5 to the annulus area of the
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piston. The piston area is now connected to the atmosphere and the piston moves backwards ata high speed.
Doubleacting
cylinder
Flowcontrol
valve
3/2 directionalcontrol valve,
pneumaticallyoperated
Checkvalve
Sourceof energy
Air-serviceunit
5/2 directionalcontrol valve,
electrically operated
3/2 directionalcontrol valve,
mechanically operatedwith roller
System with adjustable force of cylinder
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An important feature of pneumatic cylinders is their ability to produce a force. This feature is thebasis of many practical applications, such as holding parts in grippers and generating fixtureforces. However, the value of the force, produced by the cylinder is to be kept on a certain level
or should be precisely controlled.
The adjustment of the cylinder force is achieved by means of a pressure regulator. It maintainsthe desired value of the air pressure supply. As the force produced by the cylinder is proportionalto the pressure level, regulation or adjustment of the force is achieved. In practice, there are twopossible cases of adjusting the cylinder force:
adjusting the cylinder force for one direction of the cylinder stroke
adjusting the cylinder force for both directions of the cylinder stroke.
In the practice such pneumatic solutions can be found in material-handling devices, gripping andtransporting fragile parts and automated tool magazines.
System with adjustable force of cylinder. Frame 1 of 2
When the pressure regulator 1.3 is pre-set to a minimum value, the pressure at the piston area isalso at a minimum level. This low pressure generates a low value of the force that the cylindercan produce whilst moving foreword.
System with adjustable force of cylinder. Frame 2 of 2
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Similarly, when the pressure regulator 1.3 is pre-set to a maximal value, the pressure at thepiston area is high. This high pressure generates a high value of the force that the cylinder canproduce whilst moving foreword.
Pressuregauge
Double actingcylinder
Pressureregulator
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The tutorial presents a typical pneumatic solution for achieving a pre-determined sequence ofmovements of cylinder pistons. Such solution provides synchronization when several operations
are to be performed. The main operating principle is the so called blocking of the motion of thecylinder. Blocking is effected by setting definite conditions, under which the motion of a particularcylinder can be performed.
Typical practical applications of the present system can be found in automated productionssystems requiring complex boring, label-sticking and nibbling.
System with blocking the movement of the cylinder. Frame 1 of 4
The system is at neutral position when the piston of the position of the two cylinders is as shownon the figure. The pressure port of valve 1.4 is directly connected to the pressure line and theannulus area of the cylinder Z1 is under pressure. However, there is no direct connection fromthe pressure line to valve 2.4, which distributes the pressure to both areas of cylinder Z2. Thisstate of cylinder Z2 is also known as absolutely blocked.
System with blocking the movement of the cylinder. Frame 2 of 4
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When the piston of the cylinder Z1 is at cover-end position, the limit switch 2.3 is switched in theposition shown on the figure. Now, the pressure port of valve 2.4 is connected to the pressure
System with blocking the movement of the cylinder. Frame 3 of 4
Whilst the cylinder Z2 moves foreword or reaches the cover-end position, the spool of valve 2.4 isin the position as shown on the figure. This position of the valve feeds a pneumatic control
pressure to the right control port of valve 1.4 through shuttle valve 1.3. This control pressurekeeps the position of the spool of valve 1.4 as shown on the figure. The position can not beshafted even if pneumatic control signal is provided at the left control port of valve 1.4. Hencenow cylinder Z1 is blocked.
System with blocking the movement of the cylinder. Frame 4 of 4
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When the cylinder Z2 initiates a reverse motion, the spool of valve 2.4 is in the position as shownon the figure. Now the pneumatic control pressure is no longer fed to the right control port of
valve 1.4. Consequently the position of the spool of valve 1.4 can be changed by any controlsignal fed to the latter. Hence now cylinder Z1 is no longer blocked.
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5/2 directionalcontrol valve,pneumaticallyoperated
Double actingcylinder
Shuttlevalve Double acting cylinder
5/2 directionalcontrol valve,pneumatically
operated
3/2 directionalcontrol valve,mechanicallyoperated
Sourceof energy
Air-serviceunit
Hand slidevalve
3/2 directionalcontrol valve,mechanically
operated with roller
Experiment 1: Blocking the backward movement of the cylinder piston by means of acontinuously maintained control signal for forward movement.Experiment 2: Absolute blocking the cylinder motion by means of discontinuing itspressure supply line.
System with pre-defined sequence of movement of the cylinder piston rods
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The tutorial presents a typical pneumatic solution, widely used in automated systems. Thesolution illustrates the control of the sequence of operation of two cylinders achieved entirely withpneumatic components. The system operates in semi-automatic and automatic mode.
Practical examples of the presented system can be found automated packing and assembly linesand in pneumatic manipulators.
How the system works
System with pre-defined sequence of movement. Frame 1 of 5
The system is in initial position when all components are in positions as shown on the figure. Thecycle-start button is the one shifting the spool of the 3/2 hand - operated valve.
System with pre-defined sequence of movement. Frame 2 of 5
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When the button of valve 1.1 is pressed and shortly afterwards released an control pneumaticsignal is fed to the right control port of the 5/2 directional control valve 1.4. This control signalshifts the spool of the latter to the position as shown on the figure. Consequently the piston areaof cylinder Z1 is connected to the pressure line and the piston starts moving foreword.
System with pre-defined sequence of movement. Frame 3 of 5
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When the piston rod of cylinder Z1 switches valve 2.1 over, a control pneumatic signal is fed tothe right control port of the 5/2 directional control valve 2.4. This control signal shifts the spool ofthe latter to the position as shown on the figure. Consequently the piston area of cylinder Z2 isconnected to the pressure line and the piston starts moving foreword.
System with pre-defined sequence of movement. Frame 4 of 5
When the piston rod of cylinder Z2 switches valv1.2 over, a control pneumatic signal is fed to theleft control port of the 5/2 directional control valve 1.4. This control signal shifts the spool of thelatter to the position as shown on the figure. Consequently the piston area of cylinder Z1 isconnected to the pressure line and the piston starts moving backward.
System with pre-defined sequence of movement. Frame 5 of 5
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Similarly, when the piston rod of cylinder Z1 switches valve 2.2 over, a control pneumatic signal isfed to the left control port of the 5/2 directional control valve 2.4. This control signal shifts thespool of the latter to the position as shown on the figure. Consequently the piston area of cylinderZ2 is connected to the pressure line and the piston starts moving backward.
5/2 directional Double 5/2 directional
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control valve,pneumaticallyoperated
actingcylinder
control valve,pneumatically
operated
Shuttlevalve
Source ofenergy
Air-serviceunit
3/2 directional control valve,mechanically operated
3/2 directional control valve,mechanically operated
with roller
Experiment 1: Start and semiautomatic control of the pneumatic system - cycle by cycle.Experiment 2: Start and automatic control of the pneumatic system autonomous cyclerepetition.
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Decentralized peripheral system
Modern automated systems require pneumatic controls to comply to the following requirements:
ability to control a significant amount of actuators (pneumatic cylinders, rotary actuators)in order to provide high-level automation.
the flexibility to be easily re-set for the manufacturing of new products, required by themarket.
easy to install and maintain, despite the high levels of complexity.
Classical solutions, based entirely on pneumatic systems can not answer these challenges. Themodern approach to this problem is the so called "decentralized architecture". The figure belowillustrates the structure of such system.
Industrial PC Field bus PLC
Actuators Decentralized peripherals ActuatorsAs seen from the figure, the operation of many actuators is controlled by a single subsystem,called "decentralized peripheral". The latter is linked either to a personal computer (PC) or aprogrammable logical controller (PLC). The PC or PLC runs a program, which:
determines the sequence of operation of the actuators, by sending control signals to thedecentralized peripheral
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receives from the decentralized peripheral feedback signals on the state of the overallsystem. The feedback signals are generated by various types of sensors, linked to thedecentralized peripheral.
The decentralized architecture allows to control electric, pneumatic and hydraulic subsystems viaone fieldbus through one PC or PLC. More information about fieldbusses in Hydraulic systemsare given in the Continuous Control WebTrainer.This tutorial introduces the basics of the construction and configuration of decentralizedperipherals for pneumatic subsystems. The Bosch VTS 02 decentralized peripheral will be used
as an example.
Component picture
A picture of the component introduced in this tutorial, with indications of the main elements isgiven below.
Valve block: this is a monoblock system of an extruded profile. The profile houses an integratedpassive printed circuit board for the electrical control of the valves, pressure and exhaust aircanals. The two work-ports can either be incorporated in the monoblock (manifold connection) orin the body of the valve (bodyported connection). The monoblock can fit from 4 up to 16 valves. Ablanking plate can be assembled on a valve block socket if the stations on the block exceed thequantity of required valves. This allows scope for a later increase or change without effort.Different type valves can be mounted at each position of the block, depending on the particularneeds.
Input/Output unit for multiple plug module: up to 12 I/O modules can be fitted in thisdecentralized peripheral. Each I/O module has 8 connections with the following variations: 8
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Inputs; 8 Outputs; 4 Inputs and 4 Outputs. The options of a 32 I/O block or an ASI Master will notbe discussed in this tutorial.
Field bus block: This communicates with the field bus master or PLC through the Bus-in and
Bus-out connections and also provides the external power supply connection.
Configurations of the component
Depending on the particular needs, the VTS 02 decentralized peripheral can have the followingbasic configurations:
Valve block with electrical multiple connection for cases where the application does notrequire a fieldbus architecture, but the features of a manifold with pneumatic valves and electricalI/Os are required.
Field bus block and an I/O unit for cases, where the decentralized peripheral is connected tothe industrial network and does not need to have an attached valve block.
Click here to see how the decentralized peripheral is configured.
Valve block with field bus block for cases, where the decentralized peripheral is connected tothe industrial network
Click here to see how the decentralized peripheral is configured.
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Valve block with field bus block and an I/O unit for cases, where the decentralizedperipheral is connected to the industrial network. The control is achieved by a PLC or a PC.Feedback signals for the state of the system or additional control signals parts of the system areto be provided.
Basic technical specifications
The basic technical specifications of Bosch accumulators are as follows:
Maximum number of valve sockets
Type of field bus interface
Type of I/O unit
How the component works.
Decentralized peripheral system. Frame 1 of 4
At the beginning of the production cycle the cylinders are in the initial position. This position isregistered by the appropriate limit switches or sensors and fed back to the PLC via the I/O unit.
Decentralized peripheral system. Frame 2 of 4
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By starting the appropriate control program on the PLC, the operator initiates the productioncycle.
Decentralized peripheral system. Frame 3 of 4
The field bus transmits commands in the form of numerical data from the PLC to thedecentralized peripherals. Each decentralized peripheral module receives the related commandsand activates the corresponding directional control valves. The actuators, controlled by thosevalves perform the related motions. At the end of those motions they activate different sensors.
Decentralized peripheral system. Frame 4 of 4
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The I/O unit converts the signals from the sensors to digital data and transmits them via the fieldbus to the PLC (PC). The active program, on the PLC compares the received data with expectedvalues. Depending on the result of the comparison the PLC initiates the execution of subsequentproduction steps.
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Decentralizedperipheral
Double actingcylinder
5/3 directionalcontrol valve,
solenoid operated
5/2 directionalcontrol valve,
solenoid operated
Controlpanel
Programmablelogicalcontroller
Bus Interface Source ofenergy
Air-serviceunit
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Decentralized peripheral system diagnostics
Modern, highly-automated production lines are complex systems incorporating different types ofdevices and technologies. Such systems provide high quality products at very high productionrates. However, they are expensive installations and their smooth operation is crucial for theireffectiveness. This means that any delay in the production process will lead to significant lossesfor the company operating such systems. Three issues must be addressed when designing thesehighly-automated systems:
"Reliability", which means, that the production system is expected to run with very fewbreakdowns.
"Precise diagnostics", which means that is the case of breakdowns, the reason for thelatter should be quickly and precisely located.
"Ease of maintenance", which means, that once located the malfunctioning sub-systemshould be repaired in a quick and reliable fashion.
A solution to these issues is the use of decentralized peripherals. A significant advantage of thelatter is the ability to provide fast and precise diagnostics for the state of the controlled actuatorsor linked sensors. This tutorial demonstrates the diagnostic abilities of decentralized peripheralswith a simple and easy to understand automated pneumatic system. Again the Bosch VTS 02decentralized peripheral is used as an example.
Component picture
A picture of the components introduced in this tutorial, with indications of the main elements weregiven in details in Tutorial 9. The pictures below are a brief review of the material, related to theBosch VTS 02.
Valve block
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Input/Output unit for multiple plug module
Field bus block
Configurations of the component
Depending on the particular needs, the VTS 02 decentralized peripheral can have the followingbasic configurations:
Details on the configuration of the components introduced in this tutorial, with given in details inTutorial 9. The pictures below are a brief review of the material, related to the Bosch VTS 02.
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How Components Works
Decentralized peripheral system - diagnostics. Frame 1 of 4
The central controller receives detailed diagnostics information through the fieldbus. Theinformation includes status of the electrical I/O and the valves.
Each malfunction can be localized very quickly, using the built-in possibilities of the decentralizedperipheral system. This is achieved by light signals of the LED-s situated on a front cover of eachbus module. The light signals are either various frequency of blinking, steady light or LED off. By
this means the following diagnostic information can be obtained:
Condition of fuses.
Power supply availability for logic.
Condition of I/O modules.
System maintaining the pressure within certain limits. Frame 2 of 4
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The motion of the cylinder piston from left to right is achieved by switching the directional controlvalve D1 in position as shown in the figure above. The speed is determined by the flow rateprovided by the pump.
Decentralized peripheral system - diagnostics. Frame 3 of 4
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Status of bus connection.
Decentralized peripheral system - diagnostics. Frame 4 of 4
Additionally diagnostic can be made using a separate diagnostic program. This program runs onthe PLC. Basically it compares received data with expected status of the system and indicatesthe results on a screen or a panel.
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Decentralizedperipheral
Double actingcylinder
5/3 directionalcontrol valve,
solenoid operated
5/2 directionalcontrol valve,
solenoid operated
Controlpanel
Programmablelogical
controller
BusInterface
Source ofenergy
Air-serviceunit
Authorised By
SANTOSH BHARADWAJ REDDY
Email: [email protected]
More Papers and Presentations available on above site
mailto:[email protected]://d/VISHAL%20NAGMOTE/ALL%20BACUP/Users/Vishal/Gajendra/Aerospace/pp/Pneumatic%20Learning/pneumatic_systems/_vti_bin/shtml.exe/Product/Learn/Tutorial_10/Tutorial_10_diagram.htm/mapmailto:[email protected]