Calculating The Clamping Force And Speed Of Rotation - Rohm KBF-N Instructions De Service

6. Calculating the clamping force and speed of rotation

6.1 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
6.2 Determining the permitted speed of rotation
6.2.1 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
6.3 Permitted speed of rotation
The following formula applies for determining the
permitted speed of rotation for a specific machi-
ning job:
F
30
n =
perm
(Nothe the number of jaws for
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 )
spo spz z
--1
[min ] (9)
M
c
M )
c.
The size of this factor is determined by the accuracy of
the influence parameters such as loading, clamping
coefficient, etc.
F = F
sp
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 24) 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
.
S [N]
spz 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
(2)
.
spo
(3)
(7)
(8)
15