Owner's manual

6. Calculating the clamping force and speed of rotation
6.1 Determing the clamping force
6.3 Permitted speed of rotation
The following formula applies for determining the
permitted speed of rotation for a specific machi-
ning job:
n
perm
=[min
-- 1
](9)
(Nothe the number of jaws for Σ M
c.
)
.
n
6.2.1 Centrifugal force F
c
, and centrifugal moment M
c
Formulae (1), (2) and (3) produce the following result
for clamping from the outside in:
F
sp
=--F
c
[N] (4)
In this case the centrifugal force F
c
is dependent on
the mass of all jaws m
B
, the centre of gravity radius r
s
and the speed of rotation n.
The following formula can be derived:
F
c
=(m
B
.
r
s
)
.
()[N] (5)
The expression m
B
⋅ r
s
is called the centrifugal
moment M
c
M
c
=m
B
.
r
s
[mkg] (6)
The following formula applies to chucks with sliding
andfalsejawsinwhichthefalsejawsABcanbemo-
ved in order to alter the clamping area and the sliding
jaws GB approximately maintain their radial position:
M
c
=M
cGB
+M
cAB
[mkg] (7)
M
cGB
can be obtained from the table below.
M
cAB
canbecalculatedusingthefollowingformula:
M
cAB
=m
AB
⋅ r
sAB
[mkg] (8)
The clamping forces can be obtained by referring to
t he c l ampi ng f or c e/ s peed of r ot at i on di agr am
when us i ng s t andar d s er i es pr oduc t i on
jaws allocated to specific chuck by the chuck
manufacturer.
F
spo
S
sp
π
30
30
π
Do not exceed the maximum speed of rotation
n
max
of the chuck (marked on the body of the
chuck). This applies even if the calculated
permitted speed of rotation n
perm
is greater than
the maximum speed n
max
.
6.2 Determining the permitted speed of rotation
2
Chuck size 110 130 160 200 250 315 400 500 630 800
A 45 55 66,7 75 95 103 130 130 130 130
at max.
speed
B
A
Chuck
C
o
/
L
A
R
A
r
s
B 26,5 26,5 36,5 36,5 45 50 50 50 50 50
C3238535354.58080808080
Max. weight in kg 0,21 0,32 0,7 0,88 1,4 2,58 3,1 3,1 3,1 3,1
R
a
max in mm 32 38 47 63 78 106 135 185 250 335
L
a
maxinmm 18212929304545454545
Centrifugal moment M
C
GB [mkg] 0,0044 0,0217 0,0407 0,070 0,161 0,400 0,718 1,17 2,94 4,95
The c lamping force F
sp
of a rotary chuck is the total of
all jaw forces acting radially on the workpiece. The
clamping force applied before the cutting process and
with the chuck stationary is the initial clamping force
F
spo
. The clamping force F
sp
avialable during the cutting
process is, firstly, the initial clamping force F
spo
existing
with the chuck stationary. This force is then increased or
decreased by the centrifugal force F
c
on the jaws.
F
sp
=F
spo
 F
c
[N] (1)
The (--) sign is for clamping forces applied from the
outside in.
The (+) sign is for clamping forces applied from the
inside out.
The c lamping force F
sp
avialable during the cutting
process multiplied by safety factor S
z
² 1,5.
The size of this factor is determined by the accuracy of
the influence parameters such as loading, clamping
coefficient, etc.
F
sp
=F
spz
.
S
z
[N] (2)
A safety factor of S
p
² 1,5 should be taken into
consideration for the static initial clamping force F
spo
.
Consequently, the following applies for the clamping
force with the chuck stationary.
F
spo
=S
sp
.
(F
sp
 F
c
)[N] (3)
The (--) sign is for clamping forces applied from the
outside in.
The (+) sign is for clamping forces applied from the
inside out.
Important:

F
spo
-- ( F
spz
.
S
z
)
M
c

12