Siemens SINUMERIK 840D Description Of Functions page 33

02.99
Valve size
 Siemens AG 2000. All rights reserved
SINUMERIK 840D/SIMODRIVE 611 digital Descr. of Functions HLA Module (FBHLA) – 04.00 Edition
The selection of a valve for a particular application is made according to the
criteria described below.
The valve size is generally determined by the maximum flow Q
calculated from piston area A which is already known (see Section 2.3.1) and
rapid traverse v according to the following law of flow:
The nominal volumetric flow Q
actuating signal is U=+ or –10 V) only serves as a rough guide, as this value
refers to a pressure loss per control edge of ∆p=35 bar or ∆p=5 bar, as stated in
table 2-3. The actual flow under practical pressure conditions is calculated ac-
cording to the following formula:
@
Q =Q
X nom
The final valve size is calculated by way of the Bosch program "HYDRO 2",
which evaluates the pressures and flows of various alternative sizes.
Table 2-4 Extract from "HYDRO 2" program
1. Given or previously calculated data (input)
Piston diameter
Rod diameter
Counteracting force
Pump pressure
2. Alternative valve size selections (input)
Rated flow
Rated pressure drop
3. Alternative results on travel-out (output)
Speed
Pressure in A
Pressure in B
Pressure drop in inlet
Pressure drop in outlet
P
A
∆P
P
P
Fig. 2-9 Display of parameters calculated in "HYDRO2"
2.3 Configuring the hydraulic drive
=v @ A
Q
X
when the valve is completely open (i.e. when
nom
∆p
X
∆p
nom
D (mm)
d (mm)
F (kN)
p (bar)
p
Qno (l/min)
m
∆p
(bar)
v (m/min)
p (bar)
A
p (bar)
B
∆p
(bar)
PA
∆p
(bar)
BT
v
∆P
PA BT
2 Configuring
. The flow is
X
63
28
30
120
Alt 1 Alt 2 Alt 3
24 50 100
35 35 35
4,6 9,7 19,3
104.3 104,3 104,3
10,1 10,1 10,1
15,7 15,7 15,7
10,1 10,1 10,1
F
P
B
P =0
T
2-33