22
Analysis of the gripping force, input force and rotation speed using Fig. 8 is carried out
as shown below.
・
For example, in the case of QB306 standard soft jaw (mass moment 75.9kg
・
mm), it
cannot exceed 5500min
-1
(rpm), and the gripping force loss due to the centrifugal
force at this rotation speed is 38kN (approx. 3875kgf). The required static gripping
force for the dynamic gripping force (gripping force loss by static gripping force -
centrifugal force) to become 1/3 of the static gripping force is 57kN, and the required
input to obtain this gripping force is 22kN. However, it is necessary to use at the
gripping part center height H=16 mm or less.
・
If the gripping part center height H is high, it is necessary to lower the static gripping
force.
・
If the top jaw mass moment is large, the rotation speed needs to be lowered.
・
If the rotation speed is high, the gripping force loss due to the centrifugal force
becomes large. The centrifugal force is proportional to the square of the rotation
speed.
The required static gripping force and input force required at the rotation speed in use are
predicted from Fig.8, however, it contains a number of hypothetical conditions. Therefore, it
is necessary to only use these as reference, and the processing conditions must be
determined after trial cutting without fail.
・
In the case of inside diameter gripping, keep the input to 1/2 of the allowable
maximum input or less. In the case of inside diameter gripping, the length of
engagement of the master jaw and the dovetail groove is shorter when
compared to the outside diameter gripping, therefore, the chuck will break, the
work will fly out and this is dangerous.
・
In the case of using only 1 jaw for gripping reduce the input force by 2/3 or
more. If 2 jaws are used for gripping reduce the input force by 1/3 or more. If it
is used without lowering the input, the input which is normally applied evenly
onto 3 of the jaws is concentrated onto 1 or 2 of the jaws. Otherwise the chuck
will break, the work will fly out and this is dangerous.
Summary of Contents for QB300
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