ZURCONR L-CUP - may-isc.co.il

1 81 Busak+ShambanZURCONRL-CUP- Single Acting -- Innovative Design based on U-Cup -- Low Friction Properties --Material-- Polyurethane -82 Busak+ShambanZurconRL-CupR83 Busak+ShambanIntroductionThe rod sealing system is the most critical part of ahydraulic cylinder. Therefore it is expected that a rodsealing system performs under leak-free conditions in thestatic and dynamic state. Moreover it has to fulfil thelifetime of several thousand meet these requirements, Busak+Shamban hasdeveloped the ZurconRL-CupR*, a highly effective andinnovative rod sealing component.*Patent for: Europe No. EP 0724693*Patent for: US No. 5,649,711*Patent for: China No. ZL a trade a single acting polyurethane rod sealwith a unique design offering a hydrodynamic back-pumping ability over the complete working pressurerange.

2 The pressure-independent, hydrodynamic sealingability of this new sealing element requires no lubricationreservoir in the sealing area and ensures a constant andcontrolled pressure distribution over a wide pressurerange. Additionally, the seal s dynamic sealing edge hasa highly effective friction-reducing microstructure**. Thisstructure creates a constant lubrication film to prevent dryrunning, thus enabling an increased service advantages of the new ZurconRL-CupRdesign leadto the following improved properties:Advantages-Hydrodynamic back-pumping ability over the completeworking pressure range-Low friction and therefore a reductionof heatgenerated-Low breakout force even after a long period ofnon-operation-Very low stick-slip-Low increase in friction at increasing pressure-High extrusion resistance-Optimum geometry of the static sealing lip for highersealing ability-No entrapped oil and grease between seal and groove(due to notches)

3 -No pressure build-up between seal and groove OD-Long service lifeThe new ZurconRL-CupRwas designed in accordancewith customers dimensions according to ISO 5597 Part 2-Interchangeable with existing U-Cup grooves-Installation into closed grooves-Wear and extrusion resistant high-performancepolyurethane** Patent No. DE4300889C1 Application ExamplesZurconRL-CupRcan be used in all applications in whichpreviously a conventional U-Cup was applied, such as:SSSSFork liftsSSSSA gricultural machinesSSSSL ight and medium mobile hydraulicsSSSSI ndustrial hydraulicsSSSSM achine toolsSSSSI njection moulding machinesSSSS hydraulic preferred solution for tandem rod sealing systemsis the combination with the TurconRStepsealRKasprimary seal and L-CupRas secondary seal, inconjunction with a double acting DataOperating conditionsPressure: Up to 40 MPaVelocity: Up to m/sTemperature:-30_Cto+80_CMedia:Hydraul ic fluids based on mineral oilImportant Note:The above data are maximum values and cannotbe used at the same time.

4 The maximumoperating speed depends on material type,pressure, temperature and gap polyurethane Shore A 93 Colour: turquoiseZurconRL-CupR84 Busak+ShambanMethod of OperationBusak+Shamban s experience in the production ofhydrodynamic back-pumping seals such as TurconRStepsealRK, and the use of Finite Element Analysis (FEA)and other laboratory tests have led to the development ofZurconRL-CupR. The main objective in the developmentof this seal was the ability to achieve an optimum pressuredistribution over the complete pressure pressure distribution curve under the sealing lip needsto have a steep gradient on the high-pressure side and ashallow gradient on the rear of the operating principles and function of ZurconRL-CupRis similar to the well-known Figure 34 the friction values of a conventional U-Cupand of ZurconRL-CupRare being compared.

5 A highincrease in friction of the U-Cup is clearly shown betweenapproximately 5 and 15 MPa. This is due to the U-Cupbeing totally pressed on the rod surface at increasedpressure, causing elimination of the oil reservoir and dryrunning of the comparison, the L-CupRshows only a low increase infriction which is due to the smaller contact area and bettertribological behaviour. The result is a very low friction force300600900N1500 PressureU-CupL-CupRHLP 46 Rod 45 mmFigure 34 Friction dependent on pressureThe surface microstructure reduces the effective contactarea to the rod and therefore the breakout and dynamicfriction are reduced compared to seals with smoothsealing surfaces. The hollow spaces between the peaks ofthe seal and the rod are filled with oil even during longperiods without operation.

6 When starting the movementafter this period, a lubrication film is still present. Thisreduction of a large surface contact area into many smallcontact points also prevents excessive breakout frictionand short stroke oscillation, oil is retained in themicrostructures. This result would be unlikely with smoothsealing surfaces where full contact with the rod causes theoil to be pressed 1U-Cup 2L-CupRFigure 35 Friction dependent on speedFriction HeatThe effect described above can be made visible by simplymeasuring the temperature. Figure 36 shows the increasein temperature on the rod surface caused by friction,measured at a pressure of 40 MPa after 20 000 cycles. Thisexplains the prolonged service life of C100U-CupL-CupRFigure 36 Increase in temperature caused by frictionTest Conditions (Fig.)

7 36)Dimension:50 x 60 x 11 mmPressure:0/40 m/sTemperature:ambientZurconRL-CupR85 Busak+ShambanSealing GapThe recommended gap dimensions described in Figure37, depend on pressure and 10203040 Pressure MPaGap 40_CGap 80_CSealing gap mmFigure 37 Sealing gapDesign InstructionsLead-in chamfersIn order to avoid damage to the rod seal duringinstallation, lead-in chamfers and rounded edges must beprovided on the piston rods (Figure 38). If this is notpossible for design reasons, a separate installation toolmust be minimum length of the lead-in chamfer depends onthe profile size of the seal and can be seen from thefollowing , polished15_-20_Figure 38 Lead-in chamferLead-in ChamferLength C Depth* * The groove depth is calculated from: (D - dN) dimensions for D and +ShambanInstallation *LT* Gap measure S see Fig.

8 37 NFigure 39 Installation drawingTable XXVI Preferred Series / Order + + + + + + + and Part Numbers in boldaccording to ISO 5597,Edition 2 tables 4 and +ShambanB+S RU0 SEALING PARTS RSPOLYPACREU- Single Acting U-Cup -- Asymmetric, Single Lip --Material-- Polyurethane -90 Busak+ShambanU-Cup RU091 Busak+ShambanU-Cup RU0 DescriptionToday U-Cups are used primarily as seals for piston rodsin hydraulic cylinders. U-Cups in polyurethane are provenelements, due to their good mechanical properties, forstandard cylinder construction, particularly for mobilehydraulics under rough operating U-Cup is a single lip RU0 The U-Cup type RU0 is installed as a single-actingsingle-lip compact seal. The seal is installed with a simplesnap fitting and seals statically on the outside diameter viaa fixed seat.

9 It has an asymmetric seal lip profile withshortened inner lip. This form can absorb deflections in thepiston rod more easily than, U-Cup Form RU2 with itsmore rigid lip geometry. In pressure-free state, it exhibitslower frictional forces than double-lipped 40 U-Cup, type RU0 Method of OperationThe sealing effect of the U-Cup comes from the intrinsicpreload of the seal body and from the compression of theseal lips during installation. In operating condition, theradial mechanical contact forces are superimposed by thesystem low stroke speeds, U-Cups can tend to have a stick-slipeffect due to an inadequate lubrication film formation inthe seal clearance and to their material properties. Thisbehaviour corresponds to the Stribeck curve described inthe relevant pressure-adapted sealing effect-Unaffected by high loads and deflections of the pistonrod-Good resistance to clearance extrusion-Simple installation-Lower friction in the low pressure range compared withdouble-lipped DataOperating pressure:Max.

10 40 MPaSpeed:Up to m/sTemperature:Use in mineral oils:-30 Cto+80 CMedia:Mineral oil-based Note:The above data are maximum values and cannotbe used at the same time. the maximumoperating speed depends on material type,pressure, temperature and gap clearanceGuide values for the radial clearance between rod andgland in relation to the operating pressure and roddiameter can be found in Table XXVII ClearanceOperatingmax. PressureMPRadial <60 mmdN>60 values for S max given in this table apply to all types for thelow-pressure side of the U-Cup. They are designed for an operatingtemperature of thermoplastic polyurethane material used for U-Cupshas a high abrasion resistance,a lowcompression setandexhibits a high resistance to clearance turquoise colorWU9L3blue colorUAT60red colorDesign and Installation InstructionsThe different forms have different grooves, see TablesXXVIII and XXIX.