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VNK CYLINDERS USE AND MAINTENANCE INSTRUCTION
3.4 IMPORTANT:
All hydraulic rotating cylinders with a thru hole, have labyrinth seals bet-
ween the fixed manifold and the rotating part. As the oil draining takes
place by gravity, it is necessary to have a height differential between the
draining collector and the oil level in the hydraulic unit.
In order to obtain a correct discharge of the oil and to avoid any outflow
from the labyrinths note the following instructions:
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A)
The drain tube must always be kept vertical.
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B)
The drain tube must not collapse thus reducing the cross sec-
tional area for the oil flow (there are plastic or rubber tubes which have
an inside wire frame which keeps the diameter constant).
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C)
The drain tubes must have a continuous slope down to the power
unit, AVOID USING SLAG SKIMMERS which could create back pressu-
re and block the tube.
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D)
The discharge in the power unit must take place above the oil
level, and not underneath it, to avoid backpressure
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E)
The power unit must have a breather which must be kept clean and
free from constriction.
4.
HYDRAULIC POWER UNIT AND RECOMMENDED OILS
4.1 The unit's tank capacity must be at least 4 times the nominal output of
the pump measured in litres/min. (eg; with a 12 l/min pump the power unit
tank must have a capacity of at least 45-50 litres). Should this be impos-
sible, we recommend using oilcooling systems. The best operating tem-
perature for hydraulic rotating cylinders is between 35° and 60°C (even
70° C will not cause any problem).
4.2 The hydraulic system must have an aspiration filter with links of 50-60 µ
and a 10 µ feeding filter (we suggest to use filter efficiency control
systems). The delivery filter must be replaced every 6-8 months.
4.3 VNK cylinders have large oil feeding holes; in order to have a good piston
speed, the feeding circuit must have the shortest pipes possible, without
constrictions and the electrovalves must have large section for the oil
flow.
4.4 RECOMMENDED OILS:
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The oil to be used with hydraulic rotating cylinders is specified in the
ISO 3448 type HM 32 regulation. For example:
AGIP – OSO 32
ESSO – NUTO H 32 ( o TERESSO 32 )
MOBIL DTE 24 ( o DTE LIGHT )
SHELL – TELLUS 32
NOTE: We do not recommend using higher density oils because they
could create serious problems in the cylinder's rotation at high speeds
and with cold oil.
Replace the oil at least every 12 – 18 months
5.
PRECAUTIONS
5.1
Before connecting the cylinder to the machine hydraulics, ensure
there is no foreign matter and metal parts circulating in the system. Link
the two feeding tubes directly and allow the oil to circulate for about 30
minutes a maximum pressure so that it is completely filtered. Then clean
the filters.
5.2 Before operating the chucking system, operated by a cylinder, carry out
the following tests:
A)
Open and close the chuck at low pressure checking that the cylin-
der moves properly without hindrance and that there are no leaks.
B)
Rotate the chuck at low speed, checking that the delivery pipes,
drain tubes or the anti rotation bracket do not hamper this movement.
C)
Bring the pressure to operating level and make another 8-10 move-
ments.
D)
Gradually increase the rotation speed and check that the feeding oil
has a minimum temperature of 35° C before attaining the max speed.
5.3 IMPORTANT
A)
Never allow the cylinder to rotate without oil pressure. This will
damage the bearings, cause seizure of the distribution ring and the body.
B)
Never rotate the cylinder at high speed with cold oil; this could
damage the bearings and the manifold ring. We recommend making a
few movements (opening/closing) at a low speed before starting.
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C)
VNK cylinders have a safety hole in the coolant colector which,
should the drain pipe be blocked, prevents the coolant from mixing with
the oil (C and D , pag. 24).
The operator must therefore periodically inspect the collector and
the quantity of the coolant and chips in the area.
6.
ANALYSIS OF THE RISKS AND SAFETY STANDARDS.
6.1 DIRECT RISKS.
The VNK cylinder consists of two parts: one is fixed and one rotates
at high speed. As a conse quence, there is the possibility of a seizure bet-
ween the two parts in case of non-compliance with the correct installa-
tion and maintenance instructions.
A)
Installation
a1) Carefully read and follow the instructions of pos. 3 - 4 and 5 of this
manual. Special care must be given to pos. 5.1 - 5.2 and 5.3.
a2) Carefully read the trouble shooting giude, pos. 1-8.
a3)
Caution. When the cylinder is rotated for the first time, be
careful that ALL PERSONNEL STAND WELL CLEAR OF THE
CYLINDER.
B)
Use e Maintenance
To avoid a seizure during the operation, carefully follow the instructions
of pos. 3-4 and 5 of this manual.
6.2 INDIRECT RISKS
Indirect risks are those that can derive from improper working or driving
of the VNK cylinder, when clamping components with power chucks or
collets.
A)
The machine must be allowed to rotate only under the
following conditions:
a1) After having checked with a pressure gauge that the feeding circuit has
reached the requested pressure.
a2) After the proximity switches (2 pcs. or more), or other systems (e.g LPS)
have confirmed the position of "component clamped".
B)
The electric and hydraulic circuits of the machine MUST GUARAN-
TEE THAT THE COMPONENT CANNOT MOVE DURING THE SPINDLE-
ROTATION (safety against an accidental opening 1 closing of the wor-
kholding system).
C)
It is necessary to use double-solenoid valves with detented posi-
tions, TO ENSURE THAT THE POSITION IS KEPT IN THE CASE OF
LACK OF POWER (to prevent the opening of the jaws of the chuck).
D)
Inspection of the safety valves of the cylinder
After commencing to use the cylinder, it is recommended to check the
efficiency of the safety valves at intervals of 1 year.
To make this inspection it is necessary to mount 2 gauges (not supplied)
on the holes A and B (see page 24) by means of suitable fittings. Bring
the pressure to about 30 bar, alternating in the two chambers of the cylin-
der, to check that, when cutting off the feed, the pressure in the cham-
bers. does not drop below 10 bar., for at least 4 - 5 minutes.
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= Damage risk to the cylinder and/or chuck and/or machine.
= Besides damage to the cylinder and the machine, RISK OF
PHYSICAL DAMAGE TO THE OPERATORS.
KEY
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