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7. Calculating the clamping force and speed of rotation
7.1 Determing the clamping force
The clamping force F
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
. The clamping force F
spo
process is, firstly, the initial clamping force F
with the chuck stationary. This force is then increased or
decreased by the centrifugal force F
F
= F
F
sp
spo
c
The (--) sign is for clamping forces applied from the
outside in.
The (+) sign is for clamping forces applied from the
inside out.
The clamping force F
process multiplied by safety factor S
7.2 Determining the permitted speed of rotation
7.2.1 Centrifugal force F
Formulae (1), (2) and (3) produce the following result
for clamping from the outside in:
F
spo
F
=
-- F
sp
S
sp
In this case the centrifugal force F
the mass of all jaws m
and the speed of rotation n.
The following formula can be derived:
.
.
F
= (m
r
)
(
c
B
s
The expression m
B
moment M
c
.
M
= m
r
[mkg]
c
B
s
7.3 Permitted speed of rotation
The following formula applies for determining the
permitted speed of rotation for a specific machi-
ning job:
F
30
spo
n
=
perm
(Nothe the number of jaws for
C
B
R
L
A
A
8. Clamping force/speed of rotation diagram
9. Clamping force/actuating force diagram
10. Technical data
of a rotary chuck is the total of
sp
avialable during the cutting
sp
spo
on the jaws.
c
[N]
avialable during the cutting
sp
²
1,5.
z
, and centrifugal moment M
c
[N]
c
is dependent on
c
, the centre of gravity radius r
B
.
n
2
) [N]
30
r
is called the centrifugal
s
.
-- (F
S
)
spz
z
--1
[min
] (9)
M
c
M
)
c.
Chuck size
r
s
Max. weight in kg
R
max. in mm
a
L
max. in mm
a
Centrifugal moment M
see page 29-30
The size of this factor is determined by the accuracy of
the influence parameters such as loading, clamping
coefficient, etc.
F
= F
sp
spz
A safety factor of S
existing
consideration for the static initial clamping force F
Consequently, the following applies for the clamping
force with the chuck stationary.
(1)
F
= S
spo
The (--) sign is for clamping forces applied from the
outside in.
The (+) sign is for clamping forces applied from the
inside out.
The following formula applies to chucks with sliding
c
and false jaws in which the false jaws AB can be mo-
ved in order to alter the clamping area and the sliding
jaws GB approximately maintain their radial position:
M
= M
c
(4)
M
cGB can be obtained from the table below.
M
s
cAB can be calculated using the following formula:
M
= m
cAB
(5)
The clamping forces can be obtained by referring to
the clamping force/speed of rotation diagram (see
page 28) when using standard series production
jaws allocated to specific chuck by the chuck
manufacturer.
(6)
Do not exceed the maximum speed of rotation
n
of the chuck (marked on the body of the
max
chuck). This applies even if the calculated
permitted speed of rotation n
the maximum speed n
110
130
140
A
45
53
53
B
26,5
22,5
22,5
C
32
30
30
0,21
0,223
0,223
32,5
38,5
43,5
16
16
16
0,007 0,0086 0,001
GB [mkg]
C
.
S
[N]
z
²
1,5 should be taken into
p
.
(F
F
)
[N]
sp
sp
c
+ M
[mkg]
cGB
cAB
r
[mkg]
AB
sAB
Important:
is greater than
perm
.
max
160
175
200
250
55
55
67
75
26,5
26,5
36,5
36,5
38
38
53
53
0,32
0,32
0,7
0,88
52,5
60
66,5
87,5
19
19
27
27
0,017
0,019
0,047
0,077
see page 28
see page 28
(2)
.
spo
(3)
(7)
(8)
315
400
500
95
130
130
45
50
50
54,5
80
80
1,4
3,1
3,1
110
135
185
27
40
40
0,154
0,42
0,574
13
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