305 Rated lifetime calculation example Operating conditions Rail Ball screw Support bearings Load mass Maximum speed Acceleration Stroke Gravity Position Speed diagram Operating Conditions : LX2602 : C (Basic dynamic load rating)=6522N Co (Basic static load rating)=11871N : Ca (Basic dynamic load rating)=1712N Coa (Basic static load rating)=2251N : Ca (Basic dynamic load rating)=1637N Poa (Basic static load rating)=1205N : 10kg : 250mm/s : 833mm/s2 : 200mm : g=9.81m/s2 : Horizontal : (Fig. 1) : (Fig. 2) Temporary selection Use a travel distance of 200 mm with an acceleration of 833 mm/s2 and a maximum speed of 250 mm/s. Based on these conditions, assume that the LX26 series is used. (The selection software can be used on the Misumi website after customer registration has been completed.) 1 Model number for examination 2 Examination 3−1 Examination of rail In accordance with the usage conditions whereby the number of nut blocks used is one piece, multiply the load by the moment equivalent coefficient in the table. 3−2 Examination of ball screw Obtain the axial loads for the parts and the average load from the speed diagram. 3 Calculation Load for nut block 1) At constant speed Fe1=Yv Fv=Yv·W·g=1·10·9.81=98.1(N) 2) At acceleration Fe2=Yv Fv+Yp Kp Ma=0.5·98.1+1·0.17·70·0=60.95(N) 3) At deceleration Fe3=Yv Fv+Yp Kp Ma=0.5·98.1+1·0.17·70·0=60.95(N) Static safety coefficient Co Co 11871 fs= = = =121.1 Femax w·g 98.1 Rated life span Axial average load 3 1 Fm= (Fe13·L1+Fe23·L2+Fe33·L3··Fen3·Ln)=100.41(N) Ls Rated life span C 3 L= ×50=1.6×106 fw·Fm fw: Load coefficient 1.2 L : Travel distance Lifetime of ball screw Axial load 1) At constant speed Fe1=μ·W·g=0.01 × 10 × 9.81=0.981(N) 2) At acceleration Fe2=Fe1+W·a × 10−3=0.981+10·0.833 =9.311(N) 3) At deceleration Fe3=Fe1−W·a×10−3=7.352(N) Static safety coefficient Coa Coa 2251 fs= = = =241.76 Femax Fe2 9.311 V(mm/s) Ls(mm)=ℓ1+ℓ2+ℓ3 ℓ1(mm) ℓ2(mm) ℓ3(mm) t1(s) t2(s) t3(s) T(s)=t1+t2+t3 Speed diagram (Fig. 1) Status of load applied (Fig. 2) W W Single Axis Actuators (LX) Selection of Single Axis Actuators 2
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