Industrial shaft seals

gab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21,
Industrial
факс
shaft seals
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Coaxiality and runout
The total tolerance for the deviation from
coaxiality and runout should not exceed the
guideline values given in Table 27.
Axial displacement
Values for the permissible axial displacement
of the V-ring with respect to its counterface
are given in Table 28.
Counterface
Fine turned counterfaces are adequate for V-
rings. Recommended surface roughness values
are 2,5 µm for R a and 12 µm for R t .
Misalignment
V-rings can tolerate misalignment between
shaft and housing axes, i.e. deviations from the
perpendicularity between the shaft and
counterface on the housing. Guideline values
for the maximum permissible misalignment
can obtained from Diagram 11. The values
apply to V-rings of the VR1 and VR2 designs
which are axially supported on the shaft.
The permissible misalignment values for the
very compact VR3-design V-rings are appreciably
smaller. V-rings of the VR4 design, on
the other hand, have a large seal cross section
and permit larger misalignments.
Where V-rings are not axially supported on the
shaft, the maximum value obtained from the
diagram should be reduced and the following
equation should be used:
= max – 0,0005 n
where:
max
n
permissible misalignment for
V-rings without axial support
operating at speed n, degrees
maximum permissible
misalignment from Diagram 1,
degrees
rotational speed, r/min
Example:
A 50 mm diameter shaft is misaligned by 1 °
with respect to the counterface on the housing.
What speed can the shaft be run at if a V-ring
of the VR1 design is to be used without axial
support?
From Diagram 8 max = 2 °,
which gives the permissible speed
max – 2 – 1
n = 0,0005
= 0,0005 = 2.000 r/min
This corresponds to a sliding velocity of
approximately 5 m/s.
4,0
3,0
2,0
1,0
0
0
50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000
Diagram 11. Maximum premissible misalignment for V-rings of the VR1 and VR2 designs
gab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21, факс 329 (495) 22