| The
working condition of nylon shaft liner is determined
by many factors, for example: the different formula,
shaping technique, the design of shaft liner ,
installation method, loading features, running
speed, lubricant condition, the working environment
of shaft liner (temperature, humidity and the
influence of impurity), abrasion when working
etc. So, when designing shaft liner , it is necessary
to take consideration of all conditions.
1. The design of
shaft liner and the calculating of PV value
When designing of shaft liner, it is the most
important thing to achieve working condition limit
under the precondition of assuring the shaft liner
completely exerting the performance. We taking
the factor of generating heat --- the multiple
value PV of the loading of unit area P and the
surface linear velocity V to determine the using
limit . If the PV value is too big, it is easy
to cause the shaft liner temperature rising. Under
heavy loading in low speed, it is better to apply
nylon shaft liner.
The calculating of PV is as shown below:
V=лdn/60 (1)
In the formula: V—— surface linear velocity, unit:
m/s
d—— internal dia of the shaft liner, Unit:
m
n—— rotating speed of shaft liner, Unit: r/min
P=W/(dl) (2)
In the formula: P—— loading on unit area, the
ratio of total loading and the projective area
of the shaft liner, unit: Pa
W—— the total loading of the shaft liner,
Unit: N
d——internal dia of the shaft liner, Unit:
m
l——length of the shaft liner, Unit: m
2. The using of
PV value
2.1 PV limit PVa
When the environment temperature is 24℃, under
certain lubricating status, the continuous running
PV value is the PV limit --- PVa. When the environment
temperature is not 24℃, under non certain lubricating
status, the PVa is the basic value, it is corrected
by temperature correction coefficient and running
time correction coefficient. The table 1 is the
PVa of some engineering plastics. |
