[0001] The present invention relates to an improved folder for a rotogravure printing press.
[0002] Folders for rotogravure printing presses known up to now have comprised a pincer
cylinder and a counter rotating gripper cylinder parallel to and disposed substantially
in contact with one another along a generatrix. The pincer cylinder is provided externally
with an odd number (normally five) of moveable pincer units distributed along respective
rows coincident with an equivalent number of generatrices of the pincer cylinder.
The pincer cylinder further carries, in positions substantially intermediate between
each pincer unit and the next in the direction of rotation of the cylinder, a blade
or "pusher bar" operable to perform, in the region of the said contact generatrix
of the said two cylinders, hereinbelow called the "release position", a radial out
and back movement with respect to the pincer cylinder between a position totally withdrawn
within the pincer cylinder and a position in which the said pusher bar projects partially
from the pincer cylinder.
[0003] The gripper cylinder is provided externally with an even number (generally four)
of gripper units moveably disposed along respective generatrices of the gripper cylinder,
and is connected to the pincer cylinder in such a way that at each passage of a pusher
bar through the release position there is a corresponding passage of a gripper unit,
the pusher bar being interposed during its radial outward movement between the open
jaws of the gripper of the said unit.
[0004] From what has been explained above it is possible to see how in folders known until
now the number of pincer units distributed around the periphery of the pincer cylinder
is always different from the number of gripper units distributed around the periphery
of the gripper cylinder.
[0005] The above indicated difference is necessary for the purpose of being able to perform
an accumulating production, for example, a " two impression accumulated" production.
In fact, in this case, there must be an odd number of pincer units uniformly distributed
around the periphery of the pincer cylinder in such a way as to permit each pincer
unit to receive a sheet relating to the first impression - and, at the next revolution,
a sheet relating to the second impression. On the other hand, the fact that there
are an even number of gripper units distributed around the gripper cylinder enormously
facilitates the accumulating production. In fact, the avoidance of transferring the
sheet relating to the first impression during its first passage through the release
position is obtained simply by removing every alternate gripper unit from the gripper
cylinder. At the same time on the pincer cylinder there are mounted control devices
operable to inhibit the opening of the sheet locking pincers when a sheet is not transferred
upon its passage through the release position.
[0006] The operating mode described above has significant disadvantages in that, in the
first place, because of the difference in the number of pincer units and the number
of gripper units, a pincer unit cooperates with the same gripper unit only every n
revolutions, where n is the number of gripper units, thereby creating a significant
problem in the construction of pincer cylinders and gripper cylinders, and in the
adjustment of their movement.
[0007] In the second place, the modifications necessary to adapt a known folder to accumulating
production require a relatively long time to perform and leaves the movements of the
pusher blades uncontrolled. These latter, in fact, always snap outwardly as they traverse
through the release position in such a way that, when a sheet is not transferred because
there is no gripper unit at the release position, the sheet is identically engaged
by the associated pusher bar which, in some cases, can cause a displacement of the
sheet with respect to the associated pincers, and an imperfect superimposition with
respect to the next sheet.
[0008] The object of the present invention is that of providing a folder for rotogravure
printing machines which will be free from the above described disadvantages.
[0009] The said object is achieved by the present invention in that it relates to a folder
for rotogravure printing machines comprising a pincer cylinder having uniformly distributed
around its periphery a determined number of pincer units and a corresponding number
of pusher bars; a gripper cylinder disposed parallel to the said pincer cylinder in
a substantially tangential position thereto and carrying uniformly distributed around
its periphery a given number of gripper units; first actuator means for displacing
in succession each said pusher bar towards and away from an operative extracted position
starting from a retracted rest position upon passage of the pusher bar itself through
a release position facing the said gripper cylinder, and second actuator means for
causing each said pincer unit to open in coincidence with the outward displacement
of the associated pusher bar; characterised by the fact that the number of said pincer
units and the number of said gripper units are equal to one another, control means
being provided for controlling the operation of the said first and said second actuator
means according to a given programme.
[0010] Further characteristics and advantages of the present invention will become apparent
from the following description with reference to the attached drawings, which illustrate
a non-limitative embodiment thereof, in which:
Figure 1 schematically illustrates in side view a folder formed according to the principles
of the present invention;
Figure 2 is a perspective and schematic view with parts removed for clarity of a first
detail of Figure 1;
Figure 3 is a perspective and schematic view with parts removed for clarity of a second-detail-of
Figure 1;
Figures 4, 5 and 6 schematically illustrate a detail of Figure 2 in three different
operating positions; and
Figures 7, 8 and 9 schematically illustrate a detail of Figure 3 in three different
operating positions.
[0011] In Figure 1 there is illustrated a rotogravure printing machine generally indicated
1, and including at least a first printing cylinder 2 and at least a second printing
cylinder 3, the support shafts of which, respectively indicated 4 and 5, are rotatably
mounted on a support(not illustrated) - constituting the frame of the machine 1.
[0012] The cylinders 2 and 3 are able to cooperate by means of their facing surfaces, with
a continuous web 6 of paper which has a width at most equal to the length of the cylinders
2 and 3 and advances, in use, along the machine 1 at a speed equal to the peripheral
velocity of the cylinders 2 and 3. These latter carry on their outer surfaces incisions
reproducing that which it is desired to print and generally defining panels (not illustrated)
each occupying a portion of the outer surface of the respective cylinder 2, 3. The
surface of each cylinder 2, 3 is in general sub-divided in annular strips (not illustrated)
the width of which is equal to that of the said panels, and the development of which
is equal to the height of the said panels, or to a multiple thereof. In particular,
the cylinders 2 and 3 are defined as "single incision" if each of the said strips
contains a single panel, whilst they are defined as "double" or more incisions if
each of the said strips contain two or more panels in the same column and which are
different from one another.
[0013] In use, the web 6 once completely printed on both its surfaces by the rollers 2 and
3, is forwarded by means of at least one return roller 7 to a longitudinal cutting
unit 8 including a cutter cylinder 9 which, cooperating with the web 6, divides it
into a plurality of strips 10 each of which corresponds to a respective annular strip
of the said cylinders 2 and 3.
[0014] Downstream of the cutting unit 8, the strips 10 are superimposed in a predetermined
order in such a way as to form a continuous bundle 11 which is supplied, by means
of drive rollers 12 and 13 to a transverse cutting unit 14 including a cutting cylinder
15 and a counter cylinder 16. These latter, cooperating together, cut the continuous
bundle 10 into successive segments 17 which hereinbelow will be indicated with the
term "copies". The copies 17 are fed in succession, by means of an accelerator or
splitting unit 18 to a folder generally indicated 19 and are each constituted by a
bundle of superimposed sheets the number of which is equal to that of the strips 10
and having a length equal to the height of the panels (not illustrated) of the cylinders
2 and 3. In particular, each of the said sheets constitutes two pages of rotogravure
to be produced and must therefore be folded in two transversely of its height, in
the folder 19.
[0015] The folder 19 includes two counter rotating cylinders 20 and 21 keyed on to respective
shafts 22 and 23 rotatably supported by the said frame (not illustrated) of the machine
1 and disposed parallel to and at a distance from one another such that the cylinders
20 and 21 are substantially tangential to one another along a generatrix.
[0016] The cylinder 20, which hereinbelow will be indicated with the term "pincer cylinder"
has five external pincer units 24 disposed along respective generatric.es uniformly
distributed around the cylinder, and five folder units 25 each of which is disposed
between two adjacent pincer units 24.
[0017] The cylinder 21, which hereinbelow will be indicated with the term "gripper cylinder"
has five external gripper units 26 disposed along respective uniformly distributed
generatrices.
[0018] As illustrated in Figure 2, each pincer unit 24 includes two shafts 27 and 28 parallel
to the shaft 22 and rotatably supported by two end walls (not illustrated) of the
pincer cylinder 20. The shaft 27 carries, keyed thereto at one end, an orthogonal
lever 29 constituting a first rocker of an articulated twin rocker quadrilateral 30
the second rocker of which is constituted by a lever 31 keyed at one end onto a shaft
32 parallel to the shaft 27 and rotatably supported by the two end walls (not illustrated)
of the pincer cylinder 20. The free ends of the levers 29 and 31 are connected together
by means of the link 33 which carries at its connection point with the lever 31 a
roller 34 functioning as a cam follower for a cylindrical. fixed cam 35 freely mounted
on the shaft 22 and having externally, along its active profile, two recessed sections
36 and 37.
[0019] Keyed to one end of the shaft 28 is an orthogonal lever 38 constituting a first rocker
of an articulated twin rocker quadrilateral 39 the second rocker of which is constituted
by a lever 40 keyed at one end to a shaft 41 parallel to the shaft 28 and rotatably
supported by the said end walls (not illustrated) of the pincer cylinder 20. The free
ends of the levers 38 and 40 are connected together by a link 42 which carries, connected
at its connection point with the lever 40, a roller 43 serving as a cam follower for
a cylindrical cam 44 supported freely by the shaft 22 and having externally, around
its active profile, six recessed sections 45 and six recessed sections 46 disposed
alternately-and uniformly distributed around the cam.
[0020] The link 42 further carries, connected thereto, a roller 47 coaxial with the roller
43 and having the same diameter as this latter. The roller 47 serves as a cam follower
for a rotatable cylindrical cam 48 constituted by two discs 48a and 48b (Figures 4,
5 and 6) which are ridigly connected together. The cam 48 is freely supported by the
shaft 22, and of the discs 48a and 48b,the first has three and the second four raised
zones respectively indicated 49a and 49b.
[0021] As illustrated in Figures 4, 5 and 6 the zones 49a are uniformly distributed about
the disc 48a at 120
0 from one another, whilst the zones 49b are disposed in pairs in such a way that each
pair is spaced from the other by 120
0 and the zones of each pair form between one another an angle of 60°.
[0022] The zones 49 have a radius substantially equal to that of the cam 44 and extend radially
to the outside of a cylindrical profile having a radius at most equal to that of the
recessed sections 45 and 46.
[0023] The cams 44 and 48 are connected to one another in an angularly adjustable position
as will be explained below and are rotated together by a drive device 50, which in
the illustrated example is constituted,purely by way of example, by the toothed wheel
51 which can be rigidly angularly fixed to the cams 44 and 48 and coupled to a pinion
52 keyed onto a drive shaft 53 the angular velocity of which remains in a fixed ratio
different from one with the angular velocity of the shaft 22.
[0024] From the shaft 27 transversely extend bars 54, hereinafter indicated with the term
"curved pincers" interspersed with bars 55, hereinafter indicated with the term "flat
pincers" extending trarsersely from the shaft 28. The ends of the curved pincers 54
and the flat pincers 55 are moveable with the respective shafts 27 and 28 to rotate
between a closed operative position, in which they cooperate with an abutment surface
56 constituting a portion of the outer surface of the pincer cylinder 20, and an open
position, in which they are spaced from the abutment surface 56.
[0025] As illustrated in Figure 3, each folder unit 25 includes a shaft 57 parallel to the
shaft 22 and rotatably supported by the said two end walls (not illustrated) of the
pincer cylinder 20. The shaft 57 carries, keyed to one of its ends, an orthogonal
lever 58 constituting a first rocker of a double rocker articulated quadrilateral
59 the second rocker of which is constituted by a lever 60 keyed to one end of a shaft
61 parallel to the shaft 22 and rotatably supported by the said two end walls (not
illustrated) of the pincer cylinder 20. The free ends of the levers 58 and 60 are
connected together by means of a link 62 which has connected to it, at its point of
connection to the lever 60, a roller 63 serving as a cam follower both for a fixed
cylindrical cam 64 mounted freely rotatably on the shaft 22 and having externally,
around its active profile, a recessed section 65, and for a rotatable cylindrical
cam 66 freely supported by the shaft 22 and the active profile of which has at least
five projecting zones 67 the radius of which is substantially equal to that of the
cam 66, which extend radially outwardly from a cylindrical profile having a radius
at most equal to that of the recessed section 65.
[0026] As illustrated in Figures 7, 8 and 9, the zones 67 comprise three zones 67a and two
zones 67b. These latter have a width about twice that of the zones 67a and form together
an angle of 120 whilst the zones. 67a are distributed non-uniformly about the remaining
240°.
[0027] The cam 6 is driven to rotate by a drive device 68 which in the illustrated example
is constituted, purely by way of example, by a toothed wheel 69 rigidly connected
to the cam 66 and coupled to a pinion 70 keyed on a drive shaft 71 the angular velocity
of which remains in a constant ratio with the angular velocity of the shaft 22.
[0028] The shaft 57 has a longitudinally extending lateral projection 72 extending radially
from the shaft 57 and carrying connected to its free end three aligned blades 73 disposed
in a radial position with respect to the shaft 22 and constituting, as an assembly,
a pusher bar 74 moveable with the shaft 57 between a retracted rest position in which
the pusher bar 74 is disposed entirely within the outer surface of the pincer cylinder
20, and an extended operative position in which part of the pusher bar 74 projects
radially outwardly of the outer surface of the pincer cylinder 20.
[0029] The folder 19 can be set up for production with or without accumulation by suitably
adjusting the relative positions of the cams 44 and 48 and the cams 64 and 66 respectively.
[0030] Production without accumulation is effected by arranging the cams 48 and 66 in a
relative position in which none of their projecting zones 49 and 67 prevent the rollers
47 and 63 from entering the respective recessed sections 46 and 65.
[0031] In particular, as illustrated in Figure 4, the discs 48a and 48b are disposed in
such a way that the associated projecting zones 49a and 49b do not interfere with
any of the recessed sections 45 or with any of the recessed sections 46. As illustrated
in Figure 7, the phase of the cam 66 is so arranged that the roller 63, which rolls
about the axis of the shaft 22 at a velocity normally greater than that of the cams
66, passes over a double raised zone 67a before engaging the recessed section 65.
[0032] During-production without accumulation each copy 17 is received by a respective pincer
unit 24 of the pincer cylinder 20 at a loading position in which the roller 34 engages
the recessed section 36 of the fixed cam 35 and the roller 43 must again engage a
recessed section 45 of the cam 44. In other words, when a copy 17 is supplied to the
accelerator unit 18 at the associated pincer unit 24, the curved pincers 54 of this
latter are spaced from the abutment surface 56 in such a way as to permit the front
edge of the associated copy 17 to advance into contact with the surface 56. Subsequent
rotation of the pincer cylinder 20 causes disengagement of the roller 34 from the
recessed section 36, with the consequent closure of the pincers 54 on the front edge
of the said copies 17 which is thus locked onto the cylinder 20, and the subsequent
passage of the roller 43 through the recessed section 45 of the cam 44. During this
movement of the roller 43 the flat pincers 55 open coming out from under the copy
17 locked by the corresponding curved pincers 54, and then reclose over the front
edge of the copy 17. This latter, thus locked, is disposed along the outer edge of
the pincer cylinder 20 between two successive pincer units 24 and with its middle
disposed over the pusher bar 74 of the folder unit 25 interposed between the said
pair of pincer units 24.
[0033] The release of the said copy 17 from the pincer cylinder 20 takes place when the
associated pusher bar 74 passes the generatrix along which the cylinders 20 and 21
are disposed substantially in contact. The said release position is reached by the
pusher bar 74 simultaneously with the corresponding gripper unit 26 which has been
previously opened by actuator means (not illustrated) and known per se carried by
the gripper cylinder 21.
[0034] Further to what has been explained above, it is suitable to state that since the
number of gripper units 26 and that of the pusher bars 74 is the same, each pusher
bar 74 traversing the release position always couples with the same gripper unit 26.
Consequently, the synchronisation between the cylinders 20 and 21 will always be perfect
once the relative position of each pusher bar 74 ardthe associated gripper unit 26
has been adjusted.
[0035] When a pusher bar 74 reaches the release position, the roller 63 engages the recessed
section 65 of the cam 64 causing the pusher bar 74 to project out, which by raising
the middle of the associated copy 17 from the cylinder 20 engages it between the open
grippers 26. These latter, upon reclosing, grip the copy 17 folded in half separating
it from the pincer cylinder 20 and transporting it towards a utilisation point. The
complete separation of the copy 17 from the pincer cylinder 20 is allowed by the fact
that when the pusher bar 74 snaps outwardly the roller 34 of the pincer unit 24 which
precedes it in the direction of rotation of the pincer cylinder 20 engages the recessed
section 37 of the fixed cam 35 thus causing the opening of the associated curved pincers
54 and, simultaneously, the roller 43 of the said pincer unit 24 engages the recessed
section 46 of the cam 44 causing the opening of the flat pincers 55 and definitively
freeing the copy 17 already gripped by the grippers 26.
[0036] In production with accumulation, for example, two impressions with accumulation,
the copies 17 do-not become transferred one by one from the pincer cylinder 20 to
the gripper cylinder 21 as in the operation without accumulation, but rather in stacks
constituted by one copy 17 relating to a first impression and a second copy 17 relating
to a second impression superimposed over one another in a predetermined order.
[0037] This two impression operation with accumulation is made possible by suitably arranging
the phases of the cams 48 and 66, which are driven to rotate by the shafts 53 and
71 at a predetermined angular velocity different (normally less) from the speed of
rotation of the shaft 22 and, therefore, of the pincer cylinder 20.
[0038] In particular, as illustrated in Figure 8, the recessed zones 67 of the cam 66 are
superimposed over the recessed section 65 of the cam 64 in a sequence such that only
one out of two rollers 63 which traverse in succession over the cam 64 engagesthe
recessed section 65, whilst the others remain raised by the effect of one of the projecting
zones 67. Similarly, as illustrated in Figure 5, the projecting zones 49 of the cam
48 interfere with one out of each two recessed sections 46 of the cam 44 in such a
way that only one of each two rollers 43 which traverse in succession over the cam
44 engage the associated recessed section 46 thereof, whilst the others remain raised
by the effect of engagement with the associated roller 47 with one of the projecting
zones 49.
[0039] With reference to what has been described above it is suitable to state that, during
the said operation with accumulation, the cam 48 prevents a roller 43 from entering
the recessed section 46 of the cam 44 for the whole of the time that the roller 63
which follows it in the direction of rotation of the pincer cylinder 20 is prevented
from entering the recessed section 65 of the cam 64 by one of the projecting zones
67 of the cam 66.
[0040] During operation with accumulation, for example, two impressions with accumulation,
the copies 17 advanced by the pincer cylinder 20 towards the release position to be
taken up by the gripper units 26 are alternatively of a first and second type and
are related one to a first impression and the other to a second impression of the
cylinders 2 and 3. When the first copy 17 of the first type is present with its middle
in front of the gripper unit 26 disposed at the release position the rotatable cams
66 driven by the shaft 71 is arranged with one of its projecting zones 67 in correspondence
with the recessed section 65 of the cam 64 thereby preventing the lowering of the
roller 63 and, therefore, preventing the pusher bar 74 from projecting out. Simultaneously,
the cam 48 is disposed with its projecting zone 49 in correspondence with the recessed
section 46 to cooperate with the roller 47 in such a way as to prevent the roller
43 from entering the associated recessed section 46 of the cam 44, whilst the roller
44 enters normally into the recessed section 37 of the fixed cam 35.
[0041] As a consequence of this, when the middle of the said copy 17 of the first type is
located in the release position, the grippers 26 open and close normally but do not
effect transfer of the copy 17 adjacent to it given the failure of the associated
pusher bar 74 to operate, and the copy 17 remains connected to the pincer cylinder
20 by the effect of the flat pincers 55 which remain closed, whilst the curved pincers
54 open and close normally.
[0042] The said copy 17 of the first type, once it has passed the release position, is carried
back by the pincer cylinder 20 towards the loading position at which the said copy
17 is maintained connected to the pincer cylinder 20 by the flat pincers 55 whilst
the curved pincers 54 open to receive a second copy 17 (which will be of the second
type given that there are an odd number of pincer units 24), and then by the curved
pincers 54 whilst the flat pincers 55 open and then reclose onto the stack formed
by the two superimposed copies 17. These latter are then sent forward towards the
release position at which they are transferred normally to the gripper cylinder 21.
[0043] In Figures 6 and 9 the assembly of cams 44 and 48 and the cam 66 are arranged to
perform an operation with three accumulated impressions, the execution of which is
easily deducible from what has been explained above in relation to operation with
two accumulated impressions.