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NEW DEVELOPMENTS IN PNEUMATICSDr. Kurt StollFesto AG & Co., Ruiterstr. 82, D-73734 Esslingen, GermanyABSTRACTThis paper dealt with the new developments ofpneumatics in the following areas:• Pneumatic components• Industry segment specialized applications• Best before-sales and after-sales servicesKEYWORDS: Developments, Pneumatic drive,Servo control, Field-bus, valve terminal, modularsystems, dynamic simulation, databaseINTRODUCTIONPneumatics were first utilised at the beginning of thefifties. Fig. 1 shows a device built in 1955, which wasfitted with single-acting aluminium die cast cylinders. Atypical pneumatic system of that time was used in thisdevice; it consisted of cylinders and manually operatedvalves. An operator played the roll of a “logic controller”.Fig. 1 An early pneumatic systemFig. 2 A purely pneumatic sequence controller with 12inputs and 12 outputsOver the past 50 years, with the rapid developments inscience and technologies, especially in automation,mechanical, electronic and computer technologies,pneumatics has been experiencing a quick expansion anddevelopment. Take automation sequence controllers as anexample, the first pneumatic control systems functionedvia valves that were actuated by driven camshafts. In theseventies many purely pneumatically actuated sequencecontrollers such as the QUICKSTEPPER (Fig. 2), whichconsisted of several pneumatic logic elements, were usedin applications.How is pneumatics applied in today’s modern world? Iwould like to focus on the new developments inpneumatics in the following areas:• Pneumatic components• Industry segment specialized applications• Best before and after-sales servicesNEW DEVELOPMENTS IN PNEUMATICCOMPONENTSo The combination of different techniquesThe combining of pneumatics with electronics and ofpneumatics with mechanics became an obvious trend overthe last 10 years.Behind this trend is the fact that more and morepneumatic drives, sensors and valves are used in a modernautomatic machine. This means more inputs and outputsare required in the control system. A purely pneumaticcontrol system is no longer suitable to meet present demands. So in most machines today, PLCs or IPCs areused as sequence controllers together with a large numberof electro-pneumatic converters, or solenoid valves.As a result, the pneumatic suppliers are faced withdemands to improve the performance and to expand thefunctions of pneumatic components. A pneumatic valveshould be easy to install and fast switching. A pneumaticdrive should be able to move faster and more precisely.Sometimes an electro-pneumatic proportional valve isrequired to convert a continuous electronic signal intopneumatic signal.All this resulted in the combination of pneumatics,electronics and mechanics.By combining pneumatics with mechanics, customers willnot only save engineering time with regard to designingand testing, but also receive an optimised solution becausethe product they receive is proven and tested by thepneumatics manufacturer.Fig. 3 shows a swivelling/linear unit, in which a linearcylinder is combined with a rotary drive to getindependent linear and rotational movements.Fig. 3 A swivelling/linear unitFig. 4 shows pneumatic units used in an assemblingsystem. This includes a linear and rotary cylindercombined with a high precision guide unit. Excellentprecision and rigidity can be achieved with thiscombination of components.The “valve terminal” concept was introduced at thebeginning of the nineties. In recent years valve terminalshave been widely used. The origin of such a product is tomeet the demands of the larger scale control system. In avalve terminal, the valves and electronic I/Os areintegrated in accordance with specific user interfaces (Fig.5). Customers can order a valve terminal according to thespecification of their application. They will get a completefactoryFig.4 Pneumatic units with several precisionmechanical partspre-assembled and pre-tested unit. They can link the valveterminal to a PLC or IPC via the desired interface, such asmultipin or fieldbus. They can even order a valve terminalwith a PLC already integrated. In this way, applicationengineers can easily divide their control systems into acouple of sub-systems. They obtain the sub-systems fromthe suppliers with guaranteed functionalities. That is tosay, what the customers get are not only the components,but also the whole solution, a solution that suits theirapplication.Fig. 5 A valve terminal, the combination of pneumaticsand electronicsA valve terminal equipped with fieldbus connectionmakes it possible for the pneumatic system to beintegrated as a part of a factory network. Another example of combination and integration is shownas Fig. 6, a pneumatic unit with the combination of acylinder, sensors, speed control valves and directioncontrol valve. Where the interfaces to the sensor anddirection valve could be fieldbus or individualconnections.Fig. 7 is a multi controlled positioning system, apneumatic servo-positioning axis is combined with anelectrically driven axis. In this system, we can see thatboth the guided pneumatic linear cylinder DGPL and theguided electrical axis DGEL have the same mechanicalinterfaces. This makes it much easier for customers todesign their machines.Fig. 6 Cylinder, solenoid valve, speed control valvesand sensors in an integrated unitFig.7 Pneumatic and electrical drives with the samemechanical interfaceo Compact performanceIn many applications, a pneumatic control valve is to bemounted together with some moving parts of the machine.In this case, the valve should be as light and as small aspossible. On the other hand, in order to shorten machinecycle time, the control valves should be installed as closeto the cylinder as possible.Fig. 8 provides a direct comparison of a solenoid valvemade in 1961 with one made in 1997, both valves havethe same flow rate (400 l/min) but the new generation ofsolenoid valve is only 10 mm in width, while the old typeis 40 mm.Fig.8 In comparison, valves of 1961 and 1997, thesame flow rate, but a quarter of the widtho More intelligence is integrated into products.Faster movement is often desired on a machine. It is notdifficult to get a cylinder to move faster. But it is moredifficult to stop a fast moving cylinder properly (withoutvibrations or shocks).Fig. 9 shows a soft-stop cylinder, in which a displacementsensor, a 5/3 dynamic proportional valve and a smartcontroller are included. With such a system, the timetaken for the cylinder to travel from one end position tothe other can be reduced by 30%. In addition, 2 freelyselectable intermediate position settings are possible.Fig.9 Fast speed and soft stop Fig. 10 shows a pneumatic servo positioning system. Adigital smart controller is employed in such a system.Fig.10 Smart pneumatic positioning axesThe controller is robust and suitable for industrialapplications. Built-in intelligence enables it to find theoptimised control parameters. The user needs only toinput the essential application data, such as the load,stroke, diameter and so on. Or even more simply, in thecase of the SPC11 controller, just to push a “teach-in”button.o Cutting costs with the modular product conceptIn a modern highly automated machine, the controlsystem often has many functions. One solution is to makesuch products, in which all the necessary functions areintegrated, but this may incur high manufacturing costs.Fig. 11 A modular valve terminal with 26 solenoidvalves and various electronic interfacesA very elegant way is to use a modular product concept.The benefit of a modular product for customers is thatthey can order the products in modules which exactlymeet their requirements. They only pay for the functionsthey need.A modular valve terminal is shown in Fig. 11. Customerscan configure or select the number and the size of thevalves, the quantity of the electronic I/Os and so on.Fig. 12 and Fig. 13 show modular vacuum componentsand modular air service unit respectively.Fig.12 A modular vacuum system with freelycombinable suction cup holder, anglecompensator, filter and suction cupo Innovation, the new driving principleA new single-acting pneumatic drive - fluidic muscle - isshown in Fig. 14. It can output 10 times more force than astandard cylinder of equivalent diameter. Fig. 14 showssome applications of such a drive. Fig. 13 A modular air service unit with manual on-offvalve, compressed air filter and regulator,lubricator, soft-start valve, distributor andpressure switchFig. 14 Fluidic muscle and some typical applicationsIt is well known that with a pneumatic cylinder it is verydifficult to achieve slow movement without the stick-slipeffect. To overcome this disadvantage electrically drivencylinders of the same size and with the same installationinterfaces as standard pneumatic cylinders have beendeveloped and applied in applications. Customers don’tneed to make mechanical modifications to their machines.TRENDS REGARDING APPLICATIONSWith regard to pneumatic applications, one of the mostimportant tasks today is to develop more and morespecialized products for the various industry segments.Fig. 15 Pneumatic components for the food and packingindustryFig. 15 shows cylinders and valves that have beenspecially developed for the food and packaging industry,where high corrosion resistance and ease of cleaning areessential.The electronics and handling and assembly industry alsoneed pneumatic products that can meet specialrequirements. Fig 4 shows some precisely guidedpneumatic drives with very high rigidity that are suitablefor use in the handling and assembling industry. Fig. 16shows some miniature precisely guided pneumaticactuators that suit the applications in the electronicsindustry. Fig. 16 Components for the electronics industryOPTIMUM SERVICES ARE DESIREDIt is not enough nowadays just to offer customers a goodpneumatic product. Customers need more and more helpwith their everyday tasks. This is because they get lessand less time for designing, establishing and maintainingtheir machines.A very efficient way is to help the customer by providingnew software tools.An electronic catalogue using the database principlemakes it possible to access product information anddrawings quickly and easily, via function searching,image searching and other searching methods (Fig. 17).Fig. 18 shows a software tool -- ProPneu, which differsfrom a normal dynamic simulation software tool. ProPneucan not only check an existing pneumatic system viadynamic simulation but also automatically select thecomponents according to the performances required bythe customer. The customer needs only provide Propneuwith a limited amount of information concerning anapplication.The settings and parameters of the components, such asthe setting of the pneumatic cushioning and the flowcontrol valves, can be automatically optimised byPropneu, according to the criteria the user has selected.Propneu can also recommend the appropriate pneumaticcomponents for a given task, e.g. to move a defined loadin a required time and a certain distance vertically,horizontally or any inclined installation.Fig. 19 shows the software FluidDraw that assistscustomers in creating pneumatic circuits on a CADsystem. If customers need to know whether their circuitsequences are correct, then FluidSim is the rightsimulation tool.Fig. 17 Fast product accessing via the electronic catalogueFig. 18 ProPneu, an intelligent software for the selecting,simulating and optimising of a pneumatic system Fig. 19 Software for designing and simulating circuitsfor pneumatic sequencesFig. 20 3D CAD drawings on a WebsiteMore and more engineers use a CAD system formachine design, so, it is very helpful for them to get 2Dor 3D CAD drawings of the pneumatic components theyhave selected. As shown in Fig. 20, they can now easilyimport a 2D or 3D CAD drawing via the Internet.REFERENCES[1] Arnold, G., Pneumatics and Hydraulics in the Historyof Energy Technology. O+P Vol, 18, 1969[2] Stoll, Kurt, What is Pneumatics? Thesis, Universityof Stuttgart, 1958[3] Pneumatic Tips, No. 51/1994, Festo Pneumatic,Esslingen[4] Pneumatic World, 2000, No. 1, 2[5] Werner Deppert, Kurt Stoll, Cutting Costs withPneumatics, 1988, ISBN 7-111-07456-4, in 14Languages (including Chinese)[6] Stefan Hesse, 99 Examples of PneumaticApplications, 2000[7] Hong Zhou, A Smart Pneumatic Servo PositioningAxis and Its Applications, 3rd JHPS, Proceedings ofthe Third JHPS International Symposium on FluidPower, Yokohama, 1996 . specialized applications• Best before-sales and after-sales servicesKEYWORDS: Developments, Pneumatic drive,Servo control, Field-bus, valve terminal, modularsystems,. cupo Innovation, the new driving principleA new single-acting pneumatic drive - fluidic muscle - isshown in Fig. 14. It can output 10 times more force