SMW Autoblok VNK Manuel D'utilisation page 4

1. GENERAL
1.1 VNK hydraulic cylinders are the most advanced on the market as regards
speed, safety, and reliability; they have all the safety conditions required
by the Berufsgenossenschaft and by international regulations.
1.2 SAFETY VALVES. VNK cylinders have two inbuilt non-return valves
which can be inspected from the outside. They maintain the pressure in
the chambers even in the case of reduction or interruption in oil pressu-
re. (The minimum required pressure is 5 bar.)
1.3 PRESSURE RELIEF VALVES. In each VNK cylinder chamber there is a
maximum pressure valve rated to open automatically in case of over-
pressure.
1.4 PISTON STROKE CONTROL. The rear of the cylinder is equipped with
a piston stroke control system, using proximity switches (not supplied) or
using of a linear positioning system (LPS). To use this system please refer
to the specific instruction manual.
1.5 MOUNTING WITH REAR SCREWS. The VNK cylinders can be moun-
ted using rear screws (see solution 1 of fig. 2), that allow in many appli-
cations mounting of the cylinder directly onto the pulley, therefore, much
closer to the rear bearing of the spindle.
1.6 The hydraulic rotating cylinder is packed with great care prior to
despatch and is therefore safe from any damage caused by ordinary loa-
ding, transport and unloading. The external metal parts are coated with
suitable anticorrosion protection which must be removed before opera-
ting the cylinder. This is best done by a light brushing with
kerosene/paraffin, followed by the cylinder being thoroughly dried.
2. FIXING OF THE ROTATING HYDRAULIC CYLINDER TO THE LATHE
SPINDLE.
2.1 There are many different ways of mounting a rotating hydraulic cylinder
to a lathe spindle. The fixing system chosen, with or without adapter,
depends on how the rear of the spindle itself is built.
Z
2.2 In order to turn at high speed with minimum vibration, the cylinder
must be as close as possible to the rear bearing of the spindle and turn
perfectly centered in comparison to the machine's rotational axis. It is
therefore necessary before mounting the cylinder, to check that the
mating surface onto which the cylinder will bear, is running true to the fol-
lowing precision criteria:
Fig. 1
Cylinder
Concentricity A
Flatness B
2.3 Once the precision of the adapter has been checked, assemble the
cylinder on the adaptor itself, preferably using the rear fixing screws.
.
First tighten the screws slightly, then center the cylinder so that the
rotation takes place according to the following precision criteria:
4
VNK CYLINDERS USE AND MAINTENANCE INSTRUCTION
Size
≤ 170/77 ≥ 200/86
0,01 0,015
0,005 0,010
Fig. 2
Then tighten the screws fully with the torque values in the following table:
Screw nominal
Size
M8
M10
M12
M16
M20
2.4 VNK cylinders are provided with 2 threads for connection to the draw
tube, to guarantee the best adaptation to the spinde bore. The 2 threads
are the ones marked with F1 and F2 on the drawing of page 3, and both
have a centering diameter (respectively K1 and K2). When building the
draw tube, after choosing which thread to use, provide a centering dia-
meter of 5 m in K1 or K2.
3. CYLINDER CONNECTION WITH THE DRAINING AND FEEDING
HOSES.
3.1 all feeding and draining hoses must be flexible. Avoid using any rigid
or semirigid tube which could exercise an axial pressure on the collector
and damage the bearings.
3.2 Only use connectors with parallel threads and a suitable seal wa-
sher. NEVER USE CONNECTORS WITH TAPERED THREADS.
Fig. 3
Z
3.3 The feeding and draining manifold (the non rotating part of the
hydraulic cylinder) must be kept in position by using a bracket anchored
on the machine (see fig. 3 , A or B). The bracket must not exert axial pres-
sure and must have a 2-3 mm radial clearance. Keep the oil draining and
the coolant draining piping vertical, in order to encourage discharge (by
gravity).
Class 12.9
F (KN) M (Nm)
16 23
26 45
38 77
72 190
110 370