Caged Ball LM Guide Model SSR

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www.thk.ru thk-mail@ya.ru Тел. (495) 727-22-72*1: Basic dynamic load rating(C)It refers to a load with aconstant magnitude anddirection under which thenominal life (L) of a group ofidentical LM Guide unitsindependently operating is50 km.Service lifeThe service life of an LM Guide is subject to variations even under the sameoperational conditions. Therefore, it is necessary to use the nominal life definedbelow as a reference value for obtaining the service life of the LM Guide.Nominal lifeThe nominal life means the total traveldistance that 90% of a group of units of thesame LM Guide model can achieve withoutflaking (scale-like pieces on the metal surface)after individually running under the sameconditions.Service life timeOnce the nominal life (L) has been obtained,the service life time can be obtained using theequation on the right if the stroke length andthe number of reciprocations are constant.fH · fT · fC CL = ( · ) 3 50fWPCL : Nominal life (km)C : Basic dynamic load rating* 1 (N)PC : Calculated load (N)fH : Hardness factor (see Fig. 1)fT : Temperature factorfC : Contact factor (see Table 1)fW : Load factor (see Table 2)L 10 6Lh =2 RS n1 60Lh : Service life time (h)Rs : Stroke length (mm)n1 : Number of reciprocations per minute (min -1 )fHHardness factorTo ensure the achievement of the optimum load capacity of the LM Guide,the raceway hardness must be between 58 and 64 HRC.At hardness below this range, the basic dynamic and static load ratingsdecrease. Therefore, the rating values must be multiplied by therespective hardness factors (fH).Since the LM Guide has sufficient hardness, the fH value for the LM Guideis normally 1.0 unless otherwise specified.Hardness factor fH1.00.90.80.70.60.50.40.30.20.160 50 40 30 20 10Raceway hardness (HRC)Fig. 1fCContact factorWhen multiple LM blocks are used in close contact with each other, it isdifficult to achieve uniform load distribution due to moment loads andmounting-surface accuracy. When using multiple blocks in close contactwith each other, multiply the basic load rating (C or C0) by thecorresponding contact factor indicated in Table 1.Note: When uneven load distribution is expected in a large machine, consider using a contactfactor from Table 1.Table 1 Contact Factor (fC)Number of blocks used in close contact23456 or greaterNormal useContact factor fC0.810.720.660.610.61fTTemperature factorSince the service temperature of Caged Ball LM Guides is normally 80Cor below, the fT value is 1.0.fWLoad factorIn general, reciprocating machines tend to produce vibrations or impactduring operation. It is especially difficult to accurately determine allvibrations generated during high-speed operation and impacts producedeach time the machine starts and stops. Therefore, where the effects ofspeed and vibration are estimated to be significant, divide the basicdynamic load rating (C) by a load factor selected from Table 2, whichcontains empirically obtained data.FaintWeakMediumStrongTable 2 Load FactorfWVibrations/impact Speed (V) fWVery lowV0.25m/sSlow0.25V1m/sMedium1V2m/sHighV2m/s1 to 1.21.2 to 1.51.5 to 22 to 3.5
www.thk.ru thk-mail@ya.ru Тел. (495) 727-22-72SSR OUTLINEModel SSR - Product OverviewRadial Clearance StandardSince the radial clearance of an LM Guidegreatly affects the running accuracy, loadcarrying capacity and rigidity of the LMGuide, it is important to select anappropriate clearance according to theapplication.In general, selecting a negative clearance (i.e., apreload* 1 is applied) while taking into accountpossible vibrations and impact generated fromreciprocating motion favorably affects the servicelife and the accuracy.Radial clearance*1: PreloadPreload is an internal loadapplied to the rollingelements (balls, rollers,etc.) of an LM block inadvance in order toincrease its rigidity.The clearance of all modelSSR units is adjusted to thedesignated value beforebeing shipped. Therefore, itis unnecessary to adjust thepreload.Model No.Indication symbol1520253035NormalLight preloadNo symbolC1– 4 to + 2 –10 to – 4– 5 to + 2 –12 to – 5– 6 to + 3 –15 to – 6– 7 to + 4 –18 to – 7– 8 to + 4 –20 to – 8Unit: m
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Caged Ball LM Guide Model SSR

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