312 TECHNICAL INFORMATION Fig. 3 Staged Fluctuating Loads M 1M P 2M 2P Pn Mn 1P M P M P (a) M P (b) Fig. 4 Constant Fluctuating Loads Fig. 5 Sine Curve Formed Fluctuating Loads Pm: Average of Fluctuating Loads (N) - : Total Travel Distance (m) When load changes almost linearly (Fig. 4), average load Pm is approximately obtained by the following formula. Pmin: Minimum Fluctuating Load (N) Pmax: Maximum Fluctuating Load (N) 1 Pm≈ (Pmin+2 t Pmax) 3 2Load Calculation Linear Guides perform linear reciprocating motion while supporting object weight. Therefore, load applied to Linear Guides varies depending on the center of gravity of the object, thrust force applied position or changes in speed at start, stop, acceleration and deceleration. For Linear Guide selections, these conditions must be fully considered. 2Average of Fluctuating Loads In general, load applied to Linear Guides varies depending on their applications. For example, there are cases at the start and stop of reciprocating motion, during constant motion or transfer with/without a workpiece. Therefore, it requires average load under which the life equals to the one under these fluctuating loads. Table-3. Condition of Use and Load Calculation Formula Classification Operating Condition and Load 1 Horizontal Axes 2 Vertical Axes Classification Operating Condition and Load 3 Wall Mounted Horizontal Axes 4 At Acceleration/Deceleration W : Applied Load (N) P1, P2, P3, P4: Load applied to Linear Guides (N) X,Y: Linear Guide Span (mm) V: Travel Speed (mm/sec) t1: Acceleration Time (sec) t3: Deceleration Time (sec) Y X y X P P P P 1 3 4 2 W P P 1 2 P 3 P 4 W 0 0 1 P P2 P3 4P X P2S y P1 P3 P2 P4 P1S P3S W P4S 0 M1 W Thrust Thrust W 2 1 P P 3 P 4 P 0X Y X P3S P1S P P4S 2S P1 P2 , P2S P1S 4 P 3 P P3S , P4S W M 1 1 X0 y0 P1= W+ W+ W 4 2X 2Y 1 X0 y0 P2= W- W+ W 4 2X 2Y 1 X0 y0 P3= W+ W- W 4 2X 2Y 1 X0 y0 P4= W+ W- W 4 2X 2Y -1 P1=P2=P3=P4= W 2X y0 P1S=P2S=P3S=P4S= W 2X -1 P1=P2=P3=P4= W 2Y 1 X0 P1S=P3S= W+ W 4 2X 1 X0 P2S=P4S= W- W 4 2X P P 1 2 W P4 P3 1P P2 P3 4P t t t 1 2 3 t V1 X Thrust M 1 Thrust Direction of Travel Time (mm/sec) (sec) W Velocity g: Gravitational Acceleration =9.8x103mm/sec2 t When accelerating from a start t When decelerating to a stop ( ) 1 2V1t-1 P1=P3= W 1+ 4 gt t1t X ( ) 1 2V1t-1 P1=P3= W 14 gt t3t X ( ) 1 2V1t-1 P2=P4= W 14 gt t1t X ( ) 1 2V1t-1 P2=P4= W 1+ 4 gt t3t X t At constant speed 1 P1=P2=P3=P4= W 4 Fig. 5 (a) Pm≈0.65Pmax Fig. 5 (b) Pm≈0.75Pmax When load changes in stages according to the distance (Fig. 3) Travel distance -1 under load P1 Travel distance -2 under load P2 For travel distance -n under load Pn, average load Pm is obtained by the following formula. ttt 3 1 Pm= (P13-1+P23-2ttt+Pn3-n) - When load changes in a sine curve as shown on Fig. 5 (a) and (b), average load Pm is approximately obtained by the following formula. ttt
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