ROHM KFD-N - Draw-down power chucks - Manual (Page 12)

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6. Maintenance
1. In order to maintain the relia-
ble function and high quality of
chuck the grease nipples must
be lubricated regularly (see
picture).
After lubrication, move the
clamping piston several times
over its full stroke in order to
distribute the grease more
evenly. Then lubricate again.
2. Check function and clamping force after a certain
period of time depending on operating conditions.
3.Function test “pull down”:
1. Remove workpiece flat seat.
2. Clamp workpiece with the necessary operating
power.
3. Chuck body must move against the spindle acc.
to the pull-down distance.
4. Unclamp workpiece, chuck body must be in
starting position.
4.Function test “clamping force”:
Jaws must still move at a smallest possible operating
pressure of approx. 3-4 bar. As this is not an exact
method it is the best to measure the clamping force
with a load-sensing device.
If clamping force dropped too much or the chuck can-
not be moved perfectly it has to be disassembled,
cleaned and relubricated.
5. Maintenance intervals: Depending on its operating
conditions, at least however after the actual operating
time.
We recommend our special grease F 80.
Lubricate all lubricating points
Every 20 operating hours at normal
operating conditions, at heavy pollution
every 8 operating hours.
For best lubricant distribution it is recommendet to
actuate the clamping piston several times and then
relubricate.
Disassemble the chuck and clean all parts every
2000-3000 hours of operation.
7. Flat seating of workpiece
The flat seating of workpiece must usually be manufactured by the user. At sizes 220, 280 and 350 it can be mounted directly to
the distance bolt (07) or to the mounting plate.
8. Spare parts
When ordering spare parts, please quote the Ident. No. of the chuck and the item number or designation of the desired part.
The Ident. No. will be found on the face of the chuck.
9. Calculating the clamping force and speed of rotation
9.1 Determing the clamping force
The clamping 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 decrea-
sed 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 clamping force F
sp
avialable during the cutting
process multiplied by safety factor S
z
 1,5.
The size of this factor is determined by the accuracy of
the influence parameters such as loading, clamping coef-
ficient, etc.
F
sp
= F
spz
. S
z
[N] (2)
A safety factor of S
p
 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.
09241-k001-001 29.04.2004 14:52 Uhr Seite 12