Roller head lines for the production of technical rubber sheets

Roller head linesFig. 1: Line for the production of wear- and corrosion-protection linings Fig. 2: Line for the production of films for pressure expansion vessels,conveyor belts and medical productsExtruder: QSM 200/k – 16 D Sheet width: 600 to 2200 mmExtrusion head: WBK 200/2200 Sheet thickness: 0.5 to 15 mmCalender: KDI 700x2400 Speed: max. 25 m/minExtruder: QSM 120/k – 16 D Sheet width: 250 to 1700 mmExtrusion head: WBK 120/1350 Sheet thickness: 0.3 to 10 mmCalender: KDI 600x1800 Speed: max. 10 m/minFig. 3: Line for the production of semi-finished products for seals/gaskets Fig. 4: Line for the production of narrow sheets / Mini roller-head systemExtruder: QSM 150/k – 12 D Sheet width: 500 to 950 mmExtrusion head: WBK 150/1050 Sheet thickness: 0.9 to 1.5 mmCalender: KDI 400x1300 Speed: max. 10 m/minsExtruder: QSM 90/k – 14 D Sheet width: 50 to 300 mmExtrusion head: WBK 90/270 Sheet thickness: 0.3 to 5 mmCalender: KDI 200x350 Speed: max. 45 m/minFig. 5:Gear extruder and vacuum extruder in cascade arrangementFig. 6:Line for the production of tank linings, carriageway marking filmExtruder: QSM 150/k – 16 D Sheet width: 250 to 1270 mmExtrusion head: WBK 150/1400 Sheet thickness: 0.5 to 25.4 mmCalender: KDI 500x1550 Speed: max. 30 m/minRFP 1/2008 – Volume 3 19

Roller head linesence of the calender gap on the achievabletolerances is particularly great at lowsheet thicknesses. In contrast, the influenceof the calender gap is reduced at greaterthicknesses, and the thickness tolerance ofthe material sheet is determined largely bythe material distribution after the extrusionpreform head. The production of elasticNR compounds with a thickness of over 10mm places particular demands on the rollerhead system. On the one hand, the rollergap has no great influence, while on theother, reset forces in the transverse directionadversely affect the sheet tolerances.In this case, the design of the flow channelsis particularly important. The channels inthe preform head must be designed so thatthe reset forces are minimised, although noimpermissible stress is placed on the compound.This requires accurate material distributionover the complete width at thehead outlet.In order to achieve this, flow channelstoday are designed with the aid of FEM(finite element method) flow calculations.The illustration in figure 7 shows such acalculation result. The particular challengein this case, and the necessary experience,lies in optimising the flow kinetics of theperipheral area.For the optimum design of the flowchannel therefore, the rheological propertiesof the compounds must be knownin advance.4. Calender technologyThe calibration of the material sheet takesplace in the calender gap. The number of calenderrollers is determined according to theprocess task. Two or three-roller calenderscan be used (fig. 8).In order to be able to produce a planeparallel sheet with accurate thicknesstolerances, the roller head calender isequipped with one or more of the followingdevices for compensation of the rollerdeflection:• Crowning on one or more calender rollers• Crossing of one calender roller• Roller bending of the calender rollers.Fig. 7:FEM flow simulation of a preform head for different distributor geometriesFig. 9:Line for production of semi-finished productsfor the pharmaceutical industryFig. 8:Line for production of semi-finished products for V-belt manufactureExtruder: GS-Vak 90/k-16 D-m/Spw Sheet width: 120 to 1200 mmExtrusion head: WBK 90/1050 Sheet thickness: 0.5 to 25.4 mmCalender: KDI 400x1300 Speed: max. 15 m/minFig. 10: Comparison of types of cooling section(cooling medium temperature = 20 °C, ambient air = 35 °C,extrusion temperature = 100 °C, average winding temperature = 40 °C)Extruder: QSM 200/k – 16 D Sheet width 800 to 1500 mmExtrusion head: WBK 200/1650 Sheet thickness: 0.3 to 3 mmCalender: KTI 600x1800 Speed: max. 30 m/minLine speed [m/min]5045Drum cooling section with 3 x 2 drums40Air cooling section 4 x 10 m35Air cooling section 4 x 5 m30Water spray cooling 6 m25201510500 2 4 6 8 10 12 14 16 18Product thickness [mm]20 RFP 1/2008 – Volume 3

Roller head linesThe crowning of the calender rollers andthe crossing device form part of the standardequipment of a roller head calender. Theroller bending device of the calender rollersis used for high-viscosity rubber compounds,which are formed into thin sheets.Modern roller head calenders are alsoequipped with a hydraulic roller adjustmentdevice, which enables accurate positioningof the calender rollers. This also enablesthe monitoring of the maximum gapforce, which ensures reliable protection ofthe rollers against breakage resulting fromoverloads.Roller head calenders comply with thelatest safety regulations, and in additionto various emergency-off circuits, are alsoequipped with programme-controlled monitoringof the brake device for the drive ofthe calender rollers (fig. 9).5. Downstreamfollowing equipmentAfter the forming of the sheet, it mustbe cooled down to the winding temperature.The diagram (fig. 10) shows the relationshipbetween sheet thickness, linespeed and the type of cooling. Coolingdrum assemblies, each with two drums, arefrequently used in roller head lines. Coolingdrums are very effective in the case oflow sheet thicknesses. In the case of highersheet thicknesses, the cooling characteristicsare determined largely by the heat conductionin the rubber compound. In thiscase, the dwell time in the cooling sectionmust be increased. This can be achieved forexample by a multilayer air cooling section.This also enables self-threading, which isnot possible with drum cooling.Within the roller head line, it is particularlyimportant that the material is transportedcarefully. The transfer points between theindividual conveyor belts are designed withthe aid of dancers and head rollers so thatthe material sheet is not subjected to tensilestress and thereby deformed.Winding can be carried out using contactwinders or centre winders. In combinationwith a cross-cutter, the cross-cutting, theresidual winding, the replacement of thewinder and the winding take place fully automatically(fig. 11). The centre winders areequipped with an edge control device forthe material and the liner. The liner is alsounwound under tensile force control.6. Line control and regulationAn essential component of a modern rollerhead line is the line control with fully automaticprocess regulation. The optimum designof the user interfaces, both on the PLCscreen and on the PC screen, provides ergonomicsystem operation for the operator. Thedisplay language can also be switched to therelevant national language. Due to the selectedhardware of the system controls, veryhigh system availability is ensured.During the project planning and commissioningof the system, the controls areadapted and optimised to the relevant customerrequirements, in order to be ableto operate the system with short productchange times and optimum start-up technology.The graphic process visualisationand the disposition and recipe managementrepresent further essential elements for efficientproduction. For the evaluation ofpast production, the production planner andprocess engineer are provided with onlineand historical trend displays of the differentprocess parameters, production reportingand evaluation, and statistical processcontrol. These process data are available notonly on the system itself, but can also bemade available to other computers of thecustomer by networking via Intranet or Internet,enabling either centralised or decentraliseddata storage.With the aid of remote maintenance,Troester engineers can monitor every systemworldwide, provide assistance and ifFig. 11: Centre winder with cross-cutterFig. 12: Line for production of semi-finished products for pneumatic springcomponents for the automotive industryExtruder: QSM 90/k - 12 D Sheet width: 60 to 250 mmExtrusion head: WBK 90/270 Sheet thickness: 0.25 to 1 mmCalender: KDI 150x350 Speed: max. 37 m/minRFP 1/2008 – Volume 3 21

Roller head linesnecessary carry out programme modifications.This ensures quick reaction times followingsystem stoppages and rapid resumptionof production.Maintenance personnel are provided withan online maintenance management system,which draws attention at the relevant timeto what maintenance work must be carriedout. The system also provides informationon which auxiliary materials are needed forthis purpose, and displays instructions forthe performance of the work (fig. 12).7. SummaryStandard systems can rarely be used for theproduction of technical rubber goods; thismust be carried out instead with roller headlines specially designed and tailor-made to therelevant customer requirements. All the requirementscan be fulfilled thanks to the widerange of extruder designs and sizes available,with screw diameters of up to 250 mm, andthe corresponding calender equipment withroller diameters from 80 –700 mm.8. Literature[1] H.-F. Ramm, E. Seidler: Automation Options forCalenders and Extruders, Tire Technology International1995[2] G. Targiel, H. Klein: Herstellen großer Kautschukbahnenim Einfach- und Doublierverfahren,Kautschuk + Gummi Kunststoffe 50 thIssue, 1/97LSR India RoadshowMomentive, Engel and Elmet will togetherpresent a cross-country roadshow to rubberand plastics producers in the Indian market.Taking place from 25 –27 February 2008 inthe automotive hubs Pune, Delhi and Chennai,this series of events will allow manufacturersto discuss the latest advances inLSR technology directly with experts in theareas of raw materials (Momentive), moulds,coldrunner-blocks, pumps and turnkey systems(Elmet), and LSR injection mouldingmachines and systems (Engel).The roadshow will give access to expertiseacross the entire LSR value chain and the latestLSR solutions.Jointly led by representatives of the threeorganising companies the discussions will focuson a broad range of LSR topics, includingself-bonding technology, self-bleedingproducts, liquid fluorosilicone elastomers,applications, machines and machine technology,local support, and LSR pumping andmixing units. Each programme will be followedby a cocktail reception and individualdiscussions.Schedule: (daily at 5 p.m.)Pune 25 February 2008Delhi 26 February 2008Chennai 27 February 2008Speakers:Oliver Franssen (Global MarketingManager Automotive, Momentive)Paul Fattinger(Global R & D Manager, Elmet)Leo Praher (Global Sales ManagerLSR/LIM Machines, Engel)Contact: (Information, registration)V. Ramesh (Country Manager,Engel India)E-mail engel@vnsl.comTel. +91 22 2847 9851Fax +91 22 2847 9854Ashutosh Mantri (Market DevelopmentManager, Momentive)E-mail ashutosh.mantri@momentive.comTel. +91 22 4005 9350-55Fax +91 22 4005 9356Advantages of LSR manufacturinginclude:• fast cycle time though platinumcatalysed addition curing system• flash-less and trim-free partsdirectly from the machine, node-flashing or manual trimming• process can run fully automated24 hours/day• wasteless manufacturing: throughcold-runner technology no wastematerial• long flow length, low injectionpressure, moulding of highly complexparts possible• available materials for consumergoods, automotive, industrial goods,electrical connectors etc.• supplied materials are ready-to-useand are easy to pigment within theprocessAbout MomentiveMomentive Performance Materials wascreated from the sale of GE Advanced Materialsand its former joint ventures, GEBayer Silicones and GE Toshiba Silicones toApollo Management, L.P. in December 2006.The company is the world’s second-largestproducer of silicones and silicone derivativesand a global leader in the developmentand manufacture of products derived fromquartz and advanced ceramics.About EngelAs an individual brand, Engel is the biggestmanufacturer of injection mouldingmachines in the world. The Engel groupcurrently offers all technology modules forplastics processing from a single source:injection moulding machines for thermoplasticsand elastomers, tools and automaticsystems. The group has 8 productionfacilities in Europe, North America and Asia(China, Korea), own branches in 17 countries,and representations in more than 70countries. The company is based in Schwertberg,Austria.About ElmetElmet is a specialist in the field of elastomermoulding technology by means ofdesigning, manufacturing and automationof LSR, 2K, HTV and rubber injection moulds;standardised valve gate cold decks, LSR dosingsystems, LIM peripheral devices and completeturn-key production systems. The companyis located in Oftering, Austria.22 RFP 1/2008 – Volume 3