MAHR - Шариковые направляющие Marmotion - 2010 Английский язык
для размещения заказа - mahr@mahr-tools.ru
- 48 M a r M o t i o n . H i g h - p re c i s i o n ro t a r y s t ro k e b e a r i n g s
Mahr
5. Computation of the Rotary Stroke Bearing
5.4 Permissible acceleration in the case of linear movement
Installation In the case of fast linear movements, large inertia forces can be exerted on the ball cage.
With sinusoidal movements, the inertia forces are largest in the end stroke positions.
horizontal vertical
The magnitude of the inertia forces is affected by the following factors:
dw q bmax q bmax • Brass or plastic cage material
[mm] [s2/m] [m/s2] [s2/m] [m/s2] • Linear acceleration b
• Cage length l2
Plastic Ball Cage N 500 • Horizontal or vertical installation position
18 - 19 0.5 200 1.35 75 The required contact length E is calculated used quotient q from the following equation:
24 - 25 0.5 200 1.4 71
30 - 32 1.1 91 3.1 32 E = q b l2 [mm]
40 - 42 1.1 91 3.2 31 100
Brass Ball Cage N 501 b [m/s2]; l2 [mm]; q [s2/m]
4 0.7 150 0.9 110 Acceleration b for sinusoidal movement:
b = ( f )2 H [m/s2]
6 1 100 1.4 70
8 - 12 1.5 67 2 50 30 2000
14 - 16 1.75 57 2.3 43 H [mm]; f [min-1]
18 - 20 2 50 2.6 38
24 - 25 2.5 40 3.3 30 The quotient q can be taken from the following tables (Fig 29).
30 - 32 3.3 30 4.4 23
40 - 42 4 25 5.3 19 The value calculated for E [mm] is to be compared with the recommended values in
50 - 52 5 20 6.7 15 the table (Fig. 21). The larger of the two values is used in further calculations.
6.6 15 8.6 11
63 10 10 13 7.6 The tables contain recommended values for the permissible axial acceleration with a
80 10 10 14 7 ball cage in contact at its full length. These values represent average values which can
100 be exceeded, for example, by increasing the preloading value v.
Fig. 29
5.5 Permissible rotary speeds for the ball cage
Computing the rotary speed
With rotary movements, the cage speed nK – referred to the stationary bearing
component in each case – is calculated as follows:
Rotating shaft
nK = (1- k k ) nW [min-1]
+ dW 2
Rotating bush
Rotary speed of ball cage nK = (1+ k k ) nB [min-1]
+ dW 2
nk max.
dw [min-1] where:
[mm] 15000
4- 8 14000 dw [mm] = shaft diameter
10 - 12 12000 k [mm] = ball diameter
14 - 16 10000 nw [min-1] = rotary speed of shaft
18 - 20 8000 nB [min-1] = rotary speed of bush
25 6000
32 4000 Recommended values for permissible rotary speeds
40 2500
50 2000 The maximum permissible rotary speed of a rotary stroke bearing depends on the pre-
63 1500 loading value v, the load, the lubricating agent and the dissipation of the generated heat.
80 1000
100 The given values are to be regarded as recommendations for pure rotary motions.
Should a linear motion be added, the conditions will become less favorable, depending
Fig. 30 on the stroke length and frequency, so that the permissible rotary speeds will be slowed
down considerably.
With fast rotary and linear motion, it is best to separate the types of motion.
mahr@mahr-tools.ru
www.mahr-tools.ru
