ROHM KFD-N - Draw-down power chucks - Manual (Page 9)

9
To ensure a safe operation of power-operated clamping devi-
ces, particularly of chucks, on heavy-duty lathes with high
speeds certain criteria must be observed:
1. When mounting the power chuck and the actuating cylin-
der on the lathe, the following saftey requirements must
be met:
1.1 The machine spindle may only start when the clam-
ping pressure has been built up in the actuating cylin-
der and the clamping has been carried out the permis-
sible working area.
1.2 Unclamping may only be possible when the machine
spindle has completely stopped.
1.3 In case of a clamping energy failure, the workpiece
must be firmly clamped until the spindle is completely
stopped. (The Röhm safety cylinders meet this requi-
rement).
1.4 In case of a current failure and upon return of the cur-
rent supply the actual control position may not be
changed.
1.5 In case of clamping energy failure the machine
spindle must be stopped by a signal.
2. The safety instructions given in the respective operating
manual must be precisely followed.
3. After having mounted the chuck and before starting the
operation the function of the chuck must be checked.
Two important points are:
3.1 Clamping Force! The clamping force ( ±15%)
stated for the clamping device must be reached
at max. actuating force/pressure.
3.2 Stroke control! A safety range must be provided for
the stroke of the actuating piston in the front and rear
end position. The machine spindle may only start after
the actuating piston has crosssed the safety range.
Only limit switches meeting the requirements for sa-
fety limit switches in accordance with VDE 0113/12.73
section 7.1.3 may be used for monitoring fthe clam-
ping path.
4. If the max. speed of the lathe exceeds the max. speed of
the clamping device or actuating cylinder, the machine
must be equipped with a speed limitation device.
5. When the clamping device has been changed, the stroke
control must be adjusted to the new condition.
6. When calculating the required clamping force for machi-
ning a workpiece, the centrifugal force of the clamping
jaws must be considered (information for calculating the
required clamping force are contained in the end of the
Röhm catalogue product group 6).
7. A reliable operation of the power chuck can only be gua-
ranteed when the mainenace instructions contained in the
instruction manual are precisely followed. In particular the
following points must be observed:
7.1 For lubrication only the lubricants recommended in
the operating manual shall be used. (An unsuitable
lubricant can reduce the clamping force by more
than 50%).
7.2 The lubricant must reach all surfaces to be lubricated.
(At the narrow fits of the mounting parts a high pres-
sure is required for pressing in the lubricant. For this
prupose a pressure gun must be used.)
7.3 In order to distribute the grease evenly, move the
clamping piston several times to its end positions,
repeat the lubrication and then check the clamping
force.
8. Before restarting a serial machining operation and in bet-
ween the maintenance intervals the clamping force should
be checked by means of a load cell. ”Only regular checks
ensure optimum reliability”.
9. It is recommended to move the clamping piston several
times to its end positions after 500 clamping strokes at the
latest. (In this way any lubricant pushed away will be retur-
ned to the pressure surfaces. The pressure force is thus
maintained for a longer period of time).
10. When using special clamping jaws the following instruc-
tions must be observed:
10.1 The clamping jaws should be designed in such a way
that their weight and height is as low as possible. The
clamping point should possibly be close to the front
side of the chuck. (Clamping points at a larger di-
stance may cause a higher surface pressure in the
jaw guiding mechanism and may thus reduce the
clamping force considerably).
10.2 In case the special jaws are for contructional reasons
wider and/or higher as the step jaws assigned to the
clamping device, the resulting higher centrifugal for-
ces must be considered when calculating the requi-
red clamping pressure and the rated speed.
To determine the permissible speed for a certain
track, please refer to page 12, section 9.
To determine the actual gripping power, we should
like to recommend the use of our electronic gripping
power measuring system EDS. The EDS measuring
system allows you to measure the gripping power of
the idle and the rotating chuck. It is thus excellently
suited for recording changes of the gripping power
due to the centrifugal force of the jaws.
10.3 Welded models should possibly not be used. If requi-
red, the welding seams must be checked as to their
centrifugal and clamping force capacity.
10.4 The mounting screws must be arranged in such a
way that the highest possible useful moment is re-
ached.
11. The max. speed may only be used at max. applied actua-
ting force and with properly functioning chucks.
12. In the case of high speeds the chucks may only be used
below a protective hood with sufficiently large dimensions.
13. For power chucks with a jaw quick-change attachment in
in the inside of the chuck a safety device is required which
prevents the machine spindle form starting when the
clamping jaws are released.
14. After a collision the clamping device must be checked for
fissures before being used again.
1. Safety instructions and guidelines for the use of
power-operated clamping devices
09241-k001-001 29.04.2004 14:52 Uhr Seite 9