ROHM ZG/ZS, ZGU/ZSU, EG/ES - Geared scroll chucks - Manual (Page 11)

If new clamping sets are to be taken into operation on the
machine, the admissibility must be previously checked. This
also includes clamping sets or clamping set components
manufactured by the user. The admissibility is influenced by
the resistance class of the guard, the masses of the possi-
bly ejected parts (determined by calculation or weighing), the
maximum possible chuck diameter (measurement), and the
maximum possible speed of the machine. In order to reduce
the impact force to the permissible level, the permissible
masses and speeds must be determined (e.g. by obtaining
information from the machine manufacturer) and if necessary
the maximum speed of the machine must be limited. Howe-
ver, the construction of all clamping set parts (e.g. top jaws,
workpiece supports, axial clamping claws etc.) must always
be as lightweight as possible.
4. Clamping of other / additional work pieces
If special clamping sets (jaws, clamping inserts, alignment
element, positioning units, points, et cetera) are provided for
this clamping equipment, only those work pieces may be
clamped in the way the clamping sets have been designed. If
this fact is not observed, persons may be injured and mate-
rial may be damaged due to insufficient chucking forces or
unfavourable clamp positioning.
For this reason, if other and/or similar work pieces are to be
clamped with the same clamping set, the written approval by
the manufacturer shall have to be obtained.
7. Clamping range
The maximum clamping and/or displacement range in case of
movable base or top jaws may not be exceeded as otherwise
no sufficient engagement can be ensured safely between the
clamping jaw and the force transmitting component part.
8. Check of chucking force
1. Check of chucking force (general aspects)
European Directive EN 1550, section 6.2, No. d) stipulates
that static force measuring devices have to be used to check
the serviced condition at regular intervals in accordance with
the maintenance instructions. Subsequently, the chucking
force has to be checked after about forty operating hours --
independent of the clamping frequency.
If and when necessary, special chucking force measuring
jaws or devices ** (pressure cells) have to be used.
9. Stability of the work piece to be clamped
In order to ensure safe clamping of the work piece to withstand
the machining forces occurring, the work piece clamped shall
have a stability suitable for the chucking force and may be com-
pressible to a minor degree only. Non-metal materials, such as
plastics, rubber, et cetera, may be clamped and machined only
after written approval by the manufacturer !
10. Mounting and setting work
On account of the clamping movements or potential setting
movements, et cetera, short travels are covered at high forces,
in parts, in short times.
Safety requirements and rules and regulations for the use of manually operated chucks
For this reason, the drive equipment provided for the chuck
actuation shall have to be switched off explicitly for all mounting
and setting work as a matter of principle. If, however, the clam-
ping movement is required during the setting operation, clam-
ping travels of more than 4 mm
-- require the attachment of a permanent or temporary work
piece holding device
or
-- require an independently actuated holding device (e.g. cen-
tring jaws for centring and face chucks)
or
-- require a work piece loading mechanism (e.g. loading stock)
or
-- require that the setting work is carried out in hydraulic, pneu-
matic and/or electric inching operation (corresponding control
has to be possible!).
This type of auxiliary setting equipment depends basically on the
machining system used and has to be procured separately, if
and when necessary !
The machine operator has to be make sure that the movement
of the clamping equipment during the entire clamping process
does not endanger persons. For this purpose, two--hand con-
trols for clamp initiation or even better corresponding safety
equipment have to be provided.
11. Manual loading and unloading
In case of manual loading and unloading processes, a mechani-
cal hazard for the fingers caused by clamping travels larger than
4 mm has to be taken into consideration. Thus,
-- an independently actuated holding device (e.g. centring jaws
for centring and face chucks) has to be fitted
or
-- a work piece loading mechanism (e.g. loading stock) has to
be used
or
-- the clamping movements (by throttling the hydraulic supply,
for example) has to be reduced to a clamping speed of less
than 4 mm s
--1 .
12. Fastening and replacing screws
If screws are replaced or loosened, defective replacement or
fastening may lead to a hazard for persons and objects. For this
reason, the corresponding torque recommended by the manu-
facturer for the screw and the screw quality has to be used for
all fastening screws as a matter of principle, unless explicitly
stated otherwise.
The following torque table shall be applicable for all standard
sizes M5 to M24 of quality 8.8, 10.9 and 12.9:
Tightening torques in Nm:
In case of doubt, use screw quality 12.9 to replace the original
screw. As a matter of principle, quality 12.9 shall be used for all
fastening screws on clamping inserts, top jaws, positive stops,
cylinder covers, and comparable elements.
All fastening screws, which on account of their useful purpose
have to be unscrewed and tightened again subsequently (e.g.
** Recommended clamping force measuring system EDS:
EDS 50 kpl. Id.-Nr. 161425
EDS 100 kpl. Id.-Nr. 161426
EDS 50/100 kpl. Id.-Nr. 161427
Qual. M5 M6 M8 M10 M12 M14 M16 M18 M20 M22 M24
8.8 5,9 10,1 24,6 48 84 133 206 295 415 567 714 Nm
10.9 8,6 14,9 36,1 71 123 195 302 421 592 807 1017 Nm
12.9 10 17,4 42,2 83 144 229 354 492 692 945 1190 Nm
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