Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD FOR THE POSITIONING OF OPERATIVE CYLINDERS ON A
GRINDING MACHINE AND GRINDING MACHINE WHICH IMPLEMENTS
THIS METHOD
The present invention relates to a method for the
positioning of operative cylinders on a grinding machine
and a grinding machine which implements this method; it
should be pointed out that the definition "operative cy-
linders" refers, for example, to cylinders of rolling
mills for the rolling of metals, those used in paper-
mills, those used in oil-pressure applications, shafts of
marine motors and in general all cylinders made of metal-
lic and non-metallic materials which are of industrial
interest.
The grinding of the cylinders described above, and
in particular cylinders of rolling-mills or paper-mills,
has various drawbacks, associated first of all with the
encumbrance and weight of the same which are often consi-
derable.
The latter, in fact, have dimensions varying from 40
mm to 2,300 mm in diameter, 1,000 mm to 12,000 mm in
length and weights ranging from a few tens of daN up to
230-250 t.
The function assigned to these cylinders requires
that they be processed with a precision and accuracy in
the order of a few thousandths of a millimeter.
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The grinding machines which can be used for these
cylinders therefore have specific characteristics and
must not be confused with the smaller and traditional
lathes or similar machines which, in this sense, are not
capable of effecting these grinding processes.
The grinding of a cylinder must always be preceded
by a preliminary positioning phase of the latter on the
machine, which is effected by inserting the cylinder to
be ground between a piece-holder head and a tailstock
centre and subsequently supporting it between centres of
the machine and, if necessary, tightening it with one or
more lunettes or contrast devices, or resting the cylind-
er itself directly on a pair of supporting lunettes; ei-
ther of the two solutions is selected in relation to the
type of cylinder to be ground and the processing to be
effected.
In the case of the processing of so-called "thin"
cylinders, for example, or cylinders in which the diame-
ter/length ratio is particularly small (a typical example
of these is represented by cylinders of "Sendzimir" roll-
ing mills or, more generally, "cluster" rolling mills),
the known art envisages that the cylinder to be ground is
first loaded onto the grinding machine with a loading de-
vice (such as, for example, a gantry crane, a jib crane
or an automatic loading device), it is then moved until
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one of its ends is supported by the centre of the piece-
holder head, the tailstock centre is then moved until the
contact with this supports the opposite end of the cy-
linder, and finally the lunettes or contrast devices are
moved along the cylinder, so as to position them correct-
ly with respect to the part of the cylinder to be ground.
The lunettes or contrast devices are normally pro-
duced as supports suitable for opposing the thrusts that
the grinding wheel exerts on the piece being processed;
they are normally positioned at regular distances along
the cylinder, in order to uniformly oppose the forces
during the grinding process.
As the piece-holder head is fixed, all the important
distances are therefore measured from the piece-holder
head and the tailstock centre and lunettes or contrast
devices are positioned in relation to this reference,
moving them in an axial direction to move them towards or
away from the reference, depending on the length of the
cylinder.
The execution of such operations, typically defined
by the term set-up can be manual or automatic. In the
former case, the set-up time is extremely important as a
series of various operations are required, which must be
accurately effected in order to verify their correctness.
In the latter case, a reduction in the set-up times jeo-
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pardizes the simplicity and reliability of the machine,
as both the lunettes and the tailstock centre must be
equipped with suitable movement devices and relative con-
trol systems.
Another drawback linked to the known art relates to
the fact that during the loading, the cylinder must be
moved in three directions and in particular, among these,
also along the longitudinal axis, in order to be correct-
ly positioned on the grinding machine; these regulation
movements require the use of a loading device. In manual
plants, this device is typically a gantry crane or a jib
crane and the precision with which the cylinder must be
moved and positioned requires long positioning times,
skilled operators and the risk that, with an erroneous
manoeuvre, the cylinder, or machine, or both, can be dam-
aged. In automatic plants, the movement of the cylinders
is effected with 3-axis loading systems and if, on the
one hand, they reduce the manoeuvring times and increase
the safety of the same, on the other, they require ma-
chines which move the load along 3 axes and are conse-
quently, by nature, complex, costly and require mainte-
nance. The positioning of the lunettes and tailstock cen-
tre is also quite lengthy with the traditional technolo-
gy, in the sense that they must be moved along the cy-
linder to be correctly positioned, care being taken to
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measure the distances from the side of the cylinder asso-
ciated with the piece-holder head. Also in this case, if,
on the one hand, the manual solution is economical, on
the other, it requires time and accuracy on the part of
the operator, whereas although the automatic solution
guarantees operational velocity and precision, it re-
quires a movement and control mechanism for the tailstock
centre and for each of the lunettes.
In the case of manual machines, these problems are
even more serious due to the fact that cylinders having
different lengths must often be ground consecutively:
these set-up operations must therefore be effected for
each processing, with considerable time consumption.
In particular, not only must the tailstock centre be
moved each time, but also the lunettes, as the distances
from the piece-holder head (which serves as a reference)
must be measured each time and all the lunettes must
therefore be moved along the cylinder.
The general objective of the present invention is
consequently to overcome these and other drawbacks of the
known art.
This objective is achieved by a grinding method and
a grinding machine having the characteristics specified
in the enclosed independent claims and in the subclaims,
which should be considered as being an integrant part of
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the present description.
A positioning method has been conceived for these cylind-
ers which envisages at least the following steps:
- positioning the transversal, longitudinal centre-line
plane of the cylinder in correspondence with a reference
point situated between a movable piece-holder head and
tailstock centre of the machine;
- moving both the piece-holder head and the tailstock
centre until they are coupled with the cylinder.
The movement of the piece-holder head and tailstock
centre is preferably of the same entity, in the same di-
rection and opposite senses.
In this way, the reference system is identified spe-
cifically by the transversal, longitudinal centre-line
plane of the cylinder, and not already by one of its
ends, as in the known art.
For this purpose, the piece-holder head and tails-
tock centre are integral in their translation movement
with respect to the frame of the machine, for example by
coupling them both with the same screw, so that a rota-
tion of the latter causes the same movement of both, in
the same direction but in opposite senses.
In this way, the advantages obtained are evident:
firstly, it is not necessary to axially move the cylinder
on the machine to position it on the piece-holder head
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and it is therefore sufficient to use a loading device
with only two movement axes, simpler and less costly,
whether it be manual or automatic.
Furthermore, the central reference system, coincid-
ing with the longitudinal centre-line plane of the cy-
linder, offers other advantages: if, for example, an odd
number of lunettes (one, three, etc.) is used, it is not
necessary to reposition the lunette or central contrast
device each time, which is preferably fixed on the ma-
chine in the position in which the centre-line of the cy-
linder is assembled.
Similar advantages are also obtained even if the
number of lunettes is equal (two, four, etc.) as, also in
this case, the positioning of the lunettes must be symme-
trical with respect to the centre-line of the cylinder.
This advantage in terms of set-up time saving is ve-
rified in each processing and even more so when various
consecutive processings of cylinders having different
lengths must be effected on the same machine: in this
latter case, in fact, it would be necessary in the known
art to also reposition the possible central lunette each
time, whereas with the present invention, it always re-
mains in the same position.
By using the reference system situated in the cen-
tre-line of the cylinder, moreover, an additional advan-
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tage is obtained: experience has shown that it is not in
fact necessary to move the lunettes when the dimension of
the cylinders that must be consecutively processed on the
same machine varies within a range of about 0.5 meters.
It has been noted, in fact, that if the variation in
the longitudinal dimensions of the cylinders remains
within this range, all the lunettes (both the central
one, if envisaged, and the side ones) can be kept in the
same positions, thus drastically reducing the set-up
time.
Furthermore, the positioning of the side lunettes is
simplified as the distances can be measured by the cen-
tral reference system, i.e. the centre-line of the cy-
linder simplifying the movement and avoiding possible er-
rors.
The structural and functional characteristics of the
invention, as also its advantages with respect to the
known art, will appear more evident form the following
description, referring to the enclosed drawings which
show a possible practical embodiment of the same inven-
tion.
In the drawings:
- figure 1 illustrates a machine according to the
present invention;
- figure 2 illustrates a detail of the machine of
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figure 1;
- figures 3 and 4 illustrate details of the machine
of figure 1.
Describing first the positioning method, object of
the present invention, it always comprises the following
steps:
A- positioning the transversal, longitudinal centre-line
plane of the cylinder in correspondence with a reference
point situated between a movable piece-holder head and
tailstock centre of said machine;
B- moving both the piece-holder head and the tailstock
centre until they are coupled with the cylinder and sup-
porting it.
An overall version of the positioning method also
envisages the following steps:
Al- preparing a rolling cylinder to be ground;
A- positioning the transversal, longitudinal centre-line
plane of the cylinder in correspondence with a reference
point situated between a moveable piece-holder head and a
tailstock centre of the machine,
B- moving both the piece-holder head and the tailstock
centre until they are coupled with said cylinder and sup-
porting it;
C- positioning at least two supporting side lunettes or
contrast devices of said cylinder at the same distance
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from said central contrast lunette.
The reference point mentioned in step A above can
possibly coincide with the positioning of the transver-
sal, longitudinal centre-line plane of said cylinder in
correspondence with a fixed lunette with respect to the
frame of the machine and/or with respect to the side lu-
nettes.
Numerous variants can obviously be applied to the
method described, all object of the present invention; in
this sense, some of the steps of the method can be in-
verted (for example steps B. and C. can be exchanged) or
other steps of the method, relating to secondary regula-
tions of the machine can be added; or it is also possible
that the central lunette, due to a particular form and
geometry of the cylinder, may not be used.
With reference to step A, the reference point, this
is preferably fixed onto the machine and coincides with a
lunette or contrast device, in particular with the cen-
tral lunette, as will appear more evident below, in the
description of the machine. This lunette can obviously be
removed to allow the grinding of cylinders having a par-
ticular form and geometry.
Both the piece-holder head and tailstock centre can
preferably be moved so as to be always equidistant from
the reference point: their movement, in other words, is
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of the same entity and is always effected in the same di-
rection but in opposite senses.
Also with respect to the side lunettes, or those si-
tuated at the sides of the central lunette which coin-
cides with the reference point, these can be advanta-
geously moved to the same degree and in the same direc-
tion, but in opposite senses. There can be one or more of
these side lunettes but always in the same quantity on
both sides with respect to the central lunette.
In this way, the advantages discussed above are ob-
tained, as the reference point for the whole positioning
phase is no longer an end of the cylinder but its centre-
line, thus allowing the above advantages to be obtained.
As far as the machine is concerned, reference should
be made to figures 1 and 2.
The grinding machine 10 comprises a base 11 on which
a piece-holder head 13 and tailstock centre 12 are mova-
bly assembled, which serve to move and possibly support a
cylinder 14 which is positioned between them during the
grinding operation.
More specifically, the machine 10 is of the type in
which the processing cylinder is supported by two rotat-
ing centres 81 and 83 positioned in the piece-holder head
13 and tailstock centre 12.
The lunettes 20,21,22 are positioned in contact with
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the cylinder and have the function of providing a con-
trast to the possible bending of the cylinder due to the
same processing.
It should be pointed out that the machine 10 can
equivalently be of a different type, in which the lu-
nettes, in addition to having the function described
above, also have the function of supporting the whole
weight of the cylinder being processed, whereas the
piece-holder head and tailstock centre only have the
function of bringing it into rotation, to allow its
grinding.
The piece-holder head 13 comprises a single body
which is capable of translating thanks to the presence,
in the lower part, of two linear guides 80 with which it
is coupled by means of suitable sliding blocks.
The rotating centre 81 can be housed inside the body
of the piece-holder head 13, which, in some applications,
forms a rest for the cylinder. In the rear part, on the
other hand, a motor 71 can be positioned, with the rela-
tive transmission, for rotating the cylinder.
The tailstock centre 12 also comprises a body which
is capable of translating thanks to the presence of two
linear guides 80 situated in the lower part of the struc-
ture with which it is coupled by means of suitable slid-
ing blocks.
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The movable centre 83 can be housed inside the
tailstock centre 12, which, in some applications, forms a
second rest for the cylinder.
Furthermore, if required by the particular applica-
tion under examination, the tailstock centre 12 can house
a device in its lower part, which generates a preloading
through a spring device.
This preloading acts in an axial direction and guar-
antees the continuous contact between the cylinder and
two movable centres 81 and 83 and, at the same time, the
desired axial preloading, if this is required by the
processing, as is the case, for example, in the grinding
of so-called "thin" cylinders.
The machine 10 also comprises a grinding wheel which
can be moved parallelly to the axis of the cylinder, not
shown for the sake of conciseness, and in any case known
in itself in this type of grinding machine.
Both the piece-holder head 13 and tailstock centre
12 can be moved linearly along the base 11 so that they
can move towards or away from each other, to house cy-
linders having different lengths.
The piece-holder head 13 and tailstock centre 12 are
coupled to movement means which allow their linear ap-
proach or withdrawal movement to the same extent, in the
same direction and in opposite senses.
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The movement means of this example comprise a worm
screw 16 engaged with both the piece-holder head 13 and
tailstock centre 12, so that, when brought into rotation,
the screw 16 actuates both the approach or withdrawal in
the same direction along which the screw 16 extends;
these movement means are illustrated in more detail in
figure 2.
For this purpose, the screw 16, produced in a single
piece, has two threaded parts 160 and 161 with which a
corresponding female screw of the piece-holder head 13
and tailstock centre 12 is engaged.
In order to allow a movement in the same direction
and of the same entity, but in opposite senses, the two
threaded parts 160, 161 of the screw 16 have contrasting
helicoidal threadings, for example an anticlockwise
threading and a clockwise threading, preferably having
the same pitch.
It should be pointed out that two separate helicoid-
al screws with a contrasting threading can be equivalent-
ly envisaged, instead of a single screw 16, or the latter
may not be in a single piece but separable into two dif-
ferent sections connected with appropriate joints.
The screw 16 is actuated in rotation by a motor 17,
for example an electric brushless motor or the like.
In this way, by correctly positioning the cylinder
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so that its transversal longitudinal centre-line plane is
in correspondence with the reference point of the machine
and actuating the screw 16, the piece-holder head 13
and tailstock centre 12 move towards the ends of the cy-
5 linder, subsequently being coupled with it and possibly
supporting it.
It should be noted that this solution also effects a
kind of self-centering of the cylinder between the head
13 and tailstock centre 12, if in fact the cylinder were
10 not correctly positioned along its axial direction, as
both the head 13 and tailstock centre 12 move with re-
spect to a common central reference to the same degree,
in the same direction and in opposite senses, their ap-
proach movement would allow a centering of the cylinder.
This particular feature, on the one hand makes ma-
nual loading of the cylinder simpler, safer and more rap-
id, whereas on the other, it significantly facilitates
the projecting of mechanisms of a possible automatic
loading system.
The machine 10 also comprises contrast or supporting
lunettes 20,21,22.
These, in the particular case of the grinding of so-
called "thin" cylinders, must at least be present in one
unit 20, but generally in at least three units 20, 21 and
22 and normally in an odd number. The use of lunettes in
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an even number, i.e. without the central lunette, is only
envisaged in particular cases, when the geometry of the
cylinder requires this. Consequently, except for this
particular case, the set of lunettes always comprises a
central lunette 20 or, more generally, the central lu-
nette 20 and two side lunettes 21 and 22, or four side
lunettes etc.
The cylinder is assembled with its transversal, lon-
gitudinal centre-line plane (which, as in the case of so-
called "thin" or Sendzimir cylinders, often coincides
with the symmetry plane passing through the barycentre
and perpendicular to the generatrices of the cylinder) in
a position corresponding to the central lunette 20.
The latter, at least in the case mentioned above, is
consequently generally fixed in position with respect to
the machine 10 or at its base destined for resting on the
ground, and does not have to be moved when cylinders hav-
ing different lengths are being processed, as, in any
case, the longitudinal centre-line point of the cylinder
is always assembled in correspondence with said central
lunette 20.
In this sense, it is also possible to mechanically
fix the central lunette 20 to the machine 10, for example
by means of screws or bolts, or make it integral with at
least part of the base 12, so that it represents a cen-
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tral and privileged reference point for the measurement
and calculation of other dimensions.
Considering the case, for example, of three lu-
nettes, as far as the side lunettes are concerned, 21 and
22, their position can be manually regulated or, in more
evolved variants of the machine 10, they can be connected
to a specific worm screw or to the same screw 16 which
activates the piece-holder head 13 and tailstock centre
12, so that they are moved in the same direction and to
the same degree, but in opposite senses, by means of a
single and simple actuation of the screw with which they
are coupled, consequently reducing or eliminating the
risks of an incorrect positioning of both: in this way,
in fact, they cannot be positioned at different distances
from the central lunette 20, but are always advantageous-
ly equidistant with respect to the same.
In this sense, a variant envisages controlling the
position of both the lunettes 20, 21, 22 and the piece-
holder head 13 and tailstock centre 12 by means of a sin-
gle screw command and a series of threaded sleeves 90
(one for each device to be moved) shown in figures 3 and
4 enclosed.
Each sleeve 90 comprises a cylindrical mantle and is
engaged with the worm screw 16 by means of a threading
inside the same mantle.
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Each sleeve 90 can also be connected to the unit to
be moved by means of a suitable mechanism. In principle,
it should be noted that, as an alternative to the brake
blocks described hereunder, in the light of the disclo-
sures provided herein, an expert in the field can also
envisage other different solutions; for example, instead
of a brake block, the blocking means of the unit to be
moved can comprise electromagnets, mechanical coupling
means such as fixing pegs, wedges, removable interference
profiles or other similar items.
For illustrative and non-limiting purposes, one of
these coupling/decoupling means is described hereunder.
The coupling/decoupling means of the sleeve to the
part to be positioned comprise two arms 91, 92 pivoted to
the structure of the part to be moved (piece-holder head,
tailstock centre and lunette) and each provided with an
engagement end 93, 94 with said sleeve 90 and an opposite
free end 95, 96 coupled with an actuator 97.
The actuator 97 is preferably a linear actuator, for
example a gas, pneumatic, hydraulic, electric actuator or
similar: in the non-limited embodiment illustrated, it is
a hydraulic actuator equipped with a cylinder and piston
which protrudes variably from the cylinder.
The actuator 97 is coupled, preferably hinged, to
the free ends 95, 96 of the arms 91, 92; each engagement
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end 93, 94 of each arm 91, 92 is equipped with a clamp
with linings for coupling with the outer cylindrical sur-
face of the sleeve 90.
The two arms 91, 92 have their fulcrum along their
body in the points 0' and 0" so as to oscillate, so that
as the two free ends 95, 96 approach, the opposite ends
93, 94 move away and vice versa.
The machine 10 preferably comprises a single screw
16 and both the head 13 and the tailstock centre 12 and
lunettes 20, 21, 22 are equipped with these coupl-
ing/decoupling means, each having a specific correspond-
ing sleeve.
In this way, there is a plurality of sleeves along
the body of the screw, one for each coupling/decoupling
means.
The functioning can be deduced from what has been
described so far: when the actuator of one of the coupl-
ing/decoupling means is activated to close the linings
over the corresponding sleeve, the same part of the ma-
chine (head, tailstock centre or lunette) can be con-
trolled in translation as a result of the rotation of the
screw 16, by activating the latter, in fact, the sleeve,
which is prevented from rotating, moves along the screw
16, entraining in translation the element to which the
arms are pivoted.
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It is therefore possible, with a simple and accurate
system, to move head, tailstock centre and lunette to po-
sition them correctly on the base 11, drastically reduc-
ing the set-up times of the machine 10.
Furthermore, in this way, both the lunette and the
head and tailstock centre can be activated contempora-
neously or separately with a single command, obtaining an
extremely high versatility of the machine.
In short, the connection between each female screw
and the part to be moved associated with it, is obtained
by means of a system which operates in the following way:
if a certain part is to be moved, for example the tails-
tock centre, said blocking system constrains the threaded
sleeve 90 (or female screw) to the body of the tailstock
centre itself and, at the same time, prevents its rota-
tion, so that, once actuated, the screw rotates and the
female screw, constrained to the tailstock centre, cannot
rotate integrally with the screw and consequently causes
the tailstock centre to translate.
If, on the contrary, the piece-holder head is to be
moved and the tailstock centre kept immobile, it is suf-
ficient to disengage the specific sleeve from the body of
the tailstock centre and contemporaneously constrain that
of the piece-holder head; in this way, once the screw be-
gins to rotate (in this case to move the piece-holder
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head) the sleeve of the tailstock centre will rotate in-
tegrally with itself, maintaining the sleeve itself in
the same axial position and consequently not causing any
movement of the tailstock centre.
In this way, either the lunettes or the head or the
tailstock centre can be simply and rapidly activated con-
temporaneously or separately, to allow the cylinder to be
suitably positioned and supported.
There can therefore be various movement conditions
of the parts, which should be considered as being an
integral part of the method described above, for example:
1) Symmetrical positioning of the lunettes, piece-
holder head and tailstock centre with respect to
the central reference of the machine: if only the
female screw of both lunettes is integral with the
screw, they will move for the same distance but in
opposite senses, due to the constructive form of
the worm screw. Contemporaneously the female screws
of the piece-holder head and tailstock centre are
disengaged from the screw and these two groups con-
sequently remain motionless. After positioning the
lunettes, the piece-holder head and tailstock cen-
tre are positioned by making the female screws of
these integral and disengaging those of the lu-
nettes. This positioning procedure can be useful,
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for example, in the case of the grinding of symme-
trical cylinders (for example Sendzimir).
2) Asymmetrical positioning of the piece-holder head
and tailstock centre - symmetrical positioning of
the lunettes: in this case, the lunettes are syn-
chronously positioned, making both of the female
screws of the latter integral with the screw. In
this way, by actuating the screw, they will move
for the same distance but in opposite senses. After
positioning these two groups, their female screws
are disengaged from the screw. At this point, the
female screw of the piece-holder head and tailstock
centre are alternatingly made integral with the
screw, moving first one group and then the other.
3) Asymmetrical positioning of the lunettes, piece-
holder head and tailstock centre with respect to
the centre-line of the cylinder: in this case, the
groups are positioned, each time making the female
screw of one group integral with the screw, whereas
the female screws of the other groups not involved
in the movement, are disengaged. This procedure can
be very useful for moving the above parts in the
case of the grinding of asymmetrical cylinders
(such as typically hot and cold rolling cylinders),
or in applications where the piece-holder head re-
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mains fixed such as, in general, all applications
except for the grinding of Sendzimir cylinders.
Numerous alternatives to the machine 10 described so
far are possible, all considered as being an integral
part of the present invention.
The movement means for the head 13 and for the
tailstock centre 12 and/or for the side lunettes 21 and
22, for example, can be produced differently, for example
by means of a transmission belt coupled with trolleys, so
as to enable the movement of the head 13 and tailstock
centre 12 and/or lunettes, as envisaged above.
The movement means can equivalently comprise two
separate screws and two motors, even if, in this case,
the cost of the machine is higher.
The centre-line of the whole machine 10 can also ad-
vantageously coincide with the central lunette 20, making
the positioning of the cylinder even more simple and in-
tuitive.
The objectives mentioned in the preamble of the de-
scription have therefore been achieved.
The scope of the invention is defined by the follow-
ing claims.
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