Hydraulic System Solutions for Plastics Processing ... - Bosch Rexroth


Hydraulic System Solutions for Plastics Processing ... - Bosch Rexroth

IndustrialHydraulicsElectric Drivesand ControlsLinear Motion andAssembly TechnologiesPneumaticsServiceAutomationMobileHydraulicsHydraulic System Solutions forPlastics Processing MachineryYour Development Partner: The Rexroth Applications Centers

Blow Molding Machines 4Injection Molding Machines 5Clamping Unit 6Injection Process 8Wall Thickness Control 10Foaming Machines 11Auxiliary Functions 12Pressure-Flow Control 14Power Units 16Leak-free Systems 17Fieldbus Technology 18Try it for Yourself:Rexroth Simulation TechnologyIncreasing demands for high dynamicresponse, efficiency, energyconsumption, and low noise emissionfrom hydraulic systems inplastics processing machinery requireswift and accurate developmentsin new products and systems.Only best-in-class componentscan guarantee our customers a positionin the market.The simulation and constructionof mathematical models for componentsand systems can be undertakenwith the aid of a flexible andefficient virtual test stand. Systems“tested” in this way help to preventcostly development failures andmanufacture of incorrect or offaulty products. They also shortendevelopment times, reduce costs ofbasic tests, and lead directly to theoptimum solution.

M4Rexroth Offers Universal System SolutionsIdeal System Solutions for BlowMolding Machines from a SingleSourceBlow molding machineUsVT-HACD-DPQWRKEWall thickness controlEjection cylinderVT-HACD-DPCWRKEExtruder controlZAA10VClamping control

5From pressure generationthrough to axial motion –a universal and matchedconceptInjection molding machineClamping cylinderInjection cylinderScrew motorEjectorNozzle systemWRKE 4WREE 4WE WRLE LC/LFAVT-HACD-DPCVT-HACD-DPQA10

6Clamping Units – Moving Large MassesSmoothly with Speed and PrecisionRexroth offers optimized digitalclosed loop control solutions forinjection molding and blow moldingmachines: The VT-HACD-DPCis configured for applicationswhere characteristics and functionsare specially tailored to thedemanding control of closingmovements, mold protection andbreakaway forces. The positioningand controller card can beintegrated into the machine controlsystem either by analog meansor via fieldbus (DeviceNet andProfibus) interfaces.Reduced cycle times• Efficient opening and closing velocityprofiles speed and pressurecontrol• A special controller design takesinto consideration the requirementsof the hydraulics and attainsmaximum repetitive accuracy.• Active damping technology permitssmooth and swift motionsequences even with sprincy,low natural frequency clampingunits.Reduced costs• The flexibility of the programstructure allows easy adaptationto a wide range of hydraulic controlconcepts.• First-class control for both oldand new injection molding andblow molding machines minimizeswaste and protects the mold,thanks to its smooth motionsequences and highly repeatableaccuracy.• Leakages caused by hydraulicpressure spikes and shocks areeliminated.Improved process control• Versatile profile and set-upoptions for complete closed loopcontrol, even of the most complexclamping applications• True differential force controlpermits application of minimumforces, thus helping to protectthe mold, yet without affectingthe speed setting.• Position-dependent decelerationfor repeatable, swift and smoothdeceleration of toggle lever orfully-hydraulic clamping units

Greater flexibility• Adaptable to any machine control,PLC or PC• Controls the complete clampingprocess, including velocity andpressure• Configuration options simplifyadaptation to customer-specificrequirements.Improved process monitoring• Fieldbus interfaces permit accessto all parameters.• Acquisition and storing of criticalprocess data during the operatingcycle for precision process monitoringand quality controlSimple set-up and adjustmentof profile• Special closed loop control solutionsfor hydraulic systems aremore efficient than conventionalmachine controls and simplifyset-up.• Stored parameters for descriptionof Rexroth valve characteristicsmakes for easier commissioning.• Powerful software tool withgraphic real-time display acceleratesset-up.• Stored profiles reduce settingtime when changing molds.• Configuration options supportalmost any hydraulic circuit thatis equipped with proportionalvalves.

8The Injection Process — Perfect Controlwith Precision ReproducibilityWith the VT-HACD-DPQ the correctclosed loop control electronicsfor the injection process are nowalso available from Rexroth: perfectprocess control, the highestrepetitive accuracy for maximumeconomic efficiency.The positioning and controllercard VT-HACD-DPQ is easily integratedinto the machine controlsystem either by analog meansor via fieldbus interfaces.The injection processAs soon as both halves of the moldare closed, the most important partof the process begins – the injectionof the plastic.Not only the volume, but also theaccurate flowrate of the extrudedplastic is essential for the qualityof the molded parts. Being able todefine and guarantee material flowaccording to the design of the moldcavity, so that the resulting controlof the injection speed is accurateand remains independent of allother process variables, demandsthe highest level of closed loopcontrol technology.The know-how in the development,design and application of controlaxes is based on decades of experienceworking on hydraulic axiscontrollers.Rexroth has applied this know-howto design critical process steps, suchas the transition from velocity intopressure control (hold pressure)without variation and with repetitiveaccuracy.Pressure control with repetitiveaccuracy within the range offractions of a percent, is necessaryto maintain the dimensional stabilityof the injected part as well asthe mechanical integrity of themachine. The VT-HACD-DPQfrom Rexroth, now the most comprehensivecontrol package in thefield of plastics processing machinery,possesses this capability.Rexroth offers a complete system,consisting of easy-to-integratehydraulic components and matchedelectronics for the highest qualityclosed loop process control.

Wall Thickness ControlOne particular challenge to theperfect interaction between hydraulicand electronic componentscan be demonstrated by thecontrol of wall thickness in blowmolding machines. The innovativesystem solution from Rexrothfulfils all the requirements.Modular Wall Thickness (MWT)offers the correct process whetheroperation is continuous (timedependentprofile) or intermittent(path-dependent profile).It is easy to integrate into anymachine control system.The MWT System is available with a rangeof control options and different sizes.The different types of wall thicknesscylinders range from standard cylinderdiameters of 60/80/100/125/150,through to special sizes built tocustomer specifications. The wallthickness cylinder is driven by anIAC control valve size 6/10.The valve and cylinder positioningcircuit can be operated in closedloop mode with the help of the integratedaxis controller in the IACcontrol valve.Control of the wall thickness profilemay be implemented analog interfaceor with the aid of the fieldbusinterface.When using the fieldbus interfacethe wall thickness profile can bestored internally and processed inthe IAC valve to lighten the load ofthe machine control system.U sProfile specificationFieldbusalternative:analog

M11Dosing Unit for PU Foaming MachinesAccurate mixing according to requirement– high-pressure axialpiston pumps with adjustabledisplacement (volume) are usedfor measuring and delivery of polyurethanecomponents.The A2VK variable displacementpump is optimally suited to thistask. It guarantees maximum,reproducible measuring accuracyusing precision adjustment of theflow. It has proven itself over decadesof use in this application.Particular material combinationsand special sealing elements permitreliable operation with specificmedia such as polyol or isocyanate.The variable displacement pumpfeatures low-noise and low-pulsationoperation with an operatingpressure rating of up to 250 bar, aswell as high volumetric efficiency.It also permits a low inlet pressure,even for highly viscous fluids.Adjustment can either be manualby means of a hand wheel withintegral precision measuring scaleor by connecting a rod for remotecontrol. Either hydraulic or pneumaticadjusting cylinders can bebuilt on and connected to the rodfor remote control.Principle of a PU foaming machinePolyolMIsocyanateMA2VKMixing headA2VKMPU

12The Auxiliary Functions –Decisive Technology in UseThe complete system is only asgood as its individual components.This is why Rexroth worksconstantly on every detail toassure maximum potential forimprovement.EjectorPressure control to protect the moldcomponent, positioning accuracyto support robots when removingthe components, and speed controlfor synchronous ejection are allexamples of the stringent requirementsplaced on precision in moderninjection molding machines.Valves used for pressure or forcecontrol support the ejection process.Two such examples are thenew IAC valve with integrated axiscontrol for closed loop position orpressure control and the VT-HACDfrom Rexroth. Valves with specialflow characteristics permit controlboth of the ejection movement andof the pressure with a single valve.

13It therefore reduces the numberof components and the complexity,and increases not only thedynamics but also the precisionin pressure control.With these solutions not only dowe simplify the system, we alsoimprove the precision of pressurecontrol by a considerable degree.Core pullCore pull is in essence a simplefunction. The real challenge is thespeed control of the cores. As thesecores are normally part of themold, they often have no positionfeedback. So how can we controlthe movement of something thatwe are unable to measure?The solution is a flow-control functionusing a proportional throttlevalve with built in load sense. Thenew Type IAC axis controller valvefrom Rexroth unites these functionsin a single valve to make yoursystem simpler, yet at the same time,more efficient.Nozzle systemThe nozzle system controls movementof injection unit during theinjection process with force controlagainst the fixed half of the mold,in order to achieve a seal betweenthese two units. This pressure hasto be reduced before the mold opens.The traditional method comprisesa combination of a directional controland a pressure control valve.Thanks to the latest technologythese two components can be replacedby a single valve (also withIAC integrated axis controller).Screw rotationScrew rotation takes place bymeans of hydraulic motors. Theselection of motor model here isdecisive for the efficiency of themovement. As this function makesup a large part of the machinecycle appropriate care should betaken.Selecting the correct solution willdepend on the demands on themachine and its cycle.For a hydraulic solution the highestdegree of efficiency can be achievedby driving the screw motor directlyfrom a variable displacement pumpwith electro-proportional DFEadjustment (see Page 14). For machineswith mechanical variabledisplacement pump, however, theflow for controlling the screw speedis effected via a throttle valve (withsystem-dependent throttle losses).

14Consistent Optimum Control ofPressure-Flow and ForceSYHDFEE with analog OBEEfficiency and reliability – theseare the features of Rexroth pumptechnology for plastics applications.It has improved itself in alarge number of machines manufacturedworldwide.To meet the high demands placedon hydraulic systems for injectionmolding machines, pumps of theType A10VSO/A4VSO with DFEEproportional control are usuallyselected, as they generate accurateflow and pressure that is requiredfor machine functions. The DFEpump electronically controls bothflow and pressure, swiftly and withprecision, just as with all subsequentmachine cycles, and withoutrequiring any other proportionaltechnologies. Flow control withoutany throttling pressure loss makesinjection molding machines fittedwith a DFE pump the optimumsolution with respect to hydraulicefficiency.The pressure-compensated versionof the A10VSO/A4VSO pump comesas part of the standard equipmentthat most machine manufacturersuse for conventional, proportionalvalve-controlled injection moldingand blow molding machines. A widerange of control options makes theA10VSO/ A4VSO pump flexibleenough for every casting and moldingapplication.The DFE proportional pump controltechnology is also availablewith fieldbus control as a DFEC.By modifying parameters via thefieldbus the pressure control canbe optimally matched to each motionaxis in the system.

15The Rexroth SYDFE is an electrohydraulicclosed loop controlsystem based on an axial pistonvariable displacement pump usedfor the control of pressure, flowand power without throttle lossesin the energy train.Q100%FlowcommandvaluePowercommandvaluePressure command value 100%PSYDZ Preload valveHM16Pressure transducerVT-SWA Swivelangle transducerwith integralelectronicsVT-DFPEPilot valvewith integralelectronicsA10VSOAxial piston pumpSystem benefits• Pressure and flow control withhigh dynamic response• Energy savings by elimination ofthrottle losses• Easy system installation throughreduction of components• High-precision infinite controlthrough electronic closed loopoperationAvailable sizes• SYDFEx with medium pressurepump A10VSO from Size 18 toSize 140• SYHDFEx with high pressurepump A4VSO from Size 71 toSize 355Application areas• Plastic injection moldingmachines• Blow molding machines• Rubber injection presses• Diecasting machines• Different types of presses• Oil supply for test stands• and many others

16The Drive Unit forYour Plastics Processing MachinesThe heart of your machines is thepower unit with its best-in-classcomponents and the correctdesign – the “whispering powerunit”.Rexroth experience in design andconstruction promotes the continuousimprovement and innovationof low-noise power units forplastics processing machinery andother applications.DesignThe tank is a U-shape design, insideof which the motor-pump assemblyis mounted with vibration-damping.Good decoupling of structure-bornenoise using precision-matched tubes,insulating mountings, and dampingmaterial results in a system thatcan operate at an extremely lownoise level. Specially designed noisedampingtop and side covers alsocontribute to the unusually low noisevalues.Specification• Customer-supplied connectionsend at a flexible pipe fitting withshut off valves.• An enlarged tank surface supportsgood de-airation of thehydraulic fluid.• Good access, easy operation andmaintenance of all componentsare guaranteed.Characteristics• Soldered plate heat exchangers,more compact and powerful thanconventional shell and tube heatexchangers• Water-saving control valves forreduction of water consumption• Accumulator subassembly andsafety and shut-off block (if required)• Pressure filter• Recirculation filter for best oilquality• Customized designs

17Freedom:No Leakage — GuaranteedThe latest design processes andtechniques have put an end to alldiscussions on the risk of fluidleakage – a requirement, which isparticularly applicable to plasticsprocessing machinery used themedical and food industries.The use of profile support rings andplain compression rings in valveflange connections means that voidscan no longer occur on the nonpressureside in Rexroth systems.Hydrodynamic “pumping” causedby a rise and drop in pressure inthese non-pressure voids is a thingof the past – even with extremepressure pulsations of the operatingmedium.O-ring gap extrusions are also preventedand the service life correspondinglyextended, as there is nolonger radial movement of the sealingring.In comparison with conventionalwear-prone compression ring fittingsand the costly welded fittingsand flared joints, this process offersdecisive advantages:• Consistent separation of retainingand sealing functions• Additional soft seal• Easy machine conversion toDIN specification• Guarantee of sustained highquality sealO-RingO-RingFor a high level of leakage preventionfrom pipe fittings Rexroth systemsnow use profile fittings inaddition to compression rings withsoft seals.Plain compression ringsin the flange connectionprovide long-term protectionagainst fluid leakage.R-RingR-Ring

18Fieldbus Technology – Decentralized Intelligencefor More Flexibility in Modular Machine SystemsFieldbus technology – componentswith fieldbus communication offerhigh flexibility in modern systemsPumpThe DFEC offers all the advantagesof DFE control plus the benefits ofdigital electronics and fieldbustechnology. With the CANopencommunication protocol all controlinformation shown below on themachine or PLC is accessible. Theresult is improved axis control andgreater flexibility.ValvesThe IAC valve family from Rexrothoffers extensive control functionalitiesin a very confined space,specially optimized for hydraulicaxes. The directly connected sensors(analog/digital) also reduce cablingin the machine.Pump and valve functionalities• Parameter sets are available forindividual optimization of theindividual axes:– Optimization of each axis– Greater accuracy– And thus faster and moreaccurate transitions– Shorter cycle times• Selection of available parametersets in real-time• Power limiters can be switchedon or off.• Leakage compensation can beswitched on or off.• Simplified switching of masterslavepump systems• Switching between multiple pressuretransducers for improvedcontrol quality• Easy transmission of settings toother systems• Auto-calibration function– Offset of pressure transducers– Valve zero point– Swivel angle zero point– Swivel angle gain• Real-time diagnostics– Diagnostics of pump/valvestatus– Changes in system behaviorcan be diagnosed and rectified• Improved monitoring– CAN communication– Controller error– Cable break in valve, swivelangle transducer, pressuretransducer– Temperature– Supply voltage

IndustrialHydraulicsIntelligent Hydraulicsin New DimensionsThe Drive & Control CompanyRexroth offers a unique andcomprehensive range of productsand services acrosstechnologies in its six fields oftechnology and service areas –strong in high-quality individualtechnologies, combined withhighest application-specific competencein system packages withintegrated complete solutions.ElectricDrives andControlsLinearMotion andAssemblyTechnologiesPneumaticsServiceAutomationMobileHydraulicsWherever forces need to be utilizedeconomically, the advantages of industrialhydraulics are obvious –whether it is required to lift and lowerloads smoothly, perform linearor rotary movements, achieve constantacceleration, maintain givenspeeds, approach positions exactly,transmit powers or interlink sequences.Rexroth is the technology andmarket leader in industrial hydraulicswith a comprehensive productrange and distinct applicationexpertise.At Rexroth you can select from theworlds’ largest standard productrange in the field of hydraulics,application and customer-specificsystem solutions of high quality.With advanced micro-electronicsRexroth has made hydraulics evenmore powerful.For you, Rexroth is the ideal partnerfor developing highly efficientmachines and production facilities– from the first point of contact tocommissioning and throughout theentire life cycle. Teams that operateworldwide carry out the completeengineering of your systems and,if requested, up to the hand-overof turnkey systems and beyond –service included.Thanks to the use of hydraulicdrive and control technology fromRexroth you will be more competitivethan ever.Rely on service acrosstechnologiesRexroth integrates all services forthe entire product spectrum inthe field of factory and industrialautomation into a single organization:from immediate support,spare parts service, field andrepair service, retrofit/modernizationthrough to training.

Bosch Rexroth AGIndustrial HydraulicsZum Eisengießer 197816 Lohr, GermanyPhone: +49(0)9352/18-2187Fax: +49(0)9352/18-1099info.bri@boschrexroth.dewww.boschrexroth.comPrinted in GermanyRE 09402/10.04substitutes 03.02

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