Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F13/00—Common details of rotary presses or machines
  • B41F13/02—Conveying or guiding webs through presses or machines
  • B41F13/025—Registering devices

Definitions

• Device for compensating the variation in width of a flexible printing medium and printing machine comprising such a device
• the present invention relates to the field of printing, in particular to multi-color printing machines, and more particularly to devices for compensating the variation of width of flexible printing media, such as sheets or strips.
• the expansion is a function of the basis weight, width and storage conditions of the paper rolls; it can furthermore vary between two successive coils of the same production, or even between the layers of a same coil, the outer layers having been able to undergo creases during their winding and being generally more exposed to atmospheric variations (for example hygrometric) than the inner layers of the coil.
• Casters arranged at the entrance of each printing unit allow, relying on the paper web, to exert a constraint on it to reduce the width. These casters are adjustable in height to adapt the stress according to the different conditions. The contact with the ink to be avoided, they can only be used on unprinted areas, which considerably limits their scope.
• air systems are used pulsed by means of nozzles or nozzles installed in place of the previously described wheels, to deform the printable support without contact with the latter.
• the capacity of deformation of the printing medium by these systems is imperfect because their action is related to the flow of compressed air. If the flow rate is too low, the deformation is insufficient to compensate for the widening of the paper web, and if the flow rate is too high, it runs the risk of damaging or even perforating the paper strip locally at a low speed.
• the use of these pulsed air devices generates a significant consumption of compressed air and is particularly noisy due to jerky air exhaust.
• the present invention aims to provide a device for compensating for the width variation of a flexible printing medium that is simple, reliable and applicable to different speeds of scrolling the print medium.
• the compensation device must also be non-noisy and usable for printed and non-printed surfaces, so preferably without contact with the print medium. It must also be adaptable to all widths of support.
• the device according to the present invention for compensation of the variation in width of a flexible printing medium, particularly in the form of a sheet or strip, traveling, in particular in a multi-color printing machine, between generally rotary printing means organized in the form of successive printing units, by means of a directed air flow to the print medium to change its flatness, is characterized in that it comprises at least one pair of baffles disposed symmetrically on either side of the scroll axis of the print medium, each baffle comprising an air blowing chamber opening at the surface of the baffle facing the printing medium, oriented towards the rear of the deflector in the direction of the scrolling of said support, so as to produce a flow of air in the form of a blade of air, in order to facilitate, in parallel, the spacing of said support from the surface of the baffle and the accompanying movement drive of said printing medium.
• the air flow produced by the air blast chamber of the deflector is in the form of a thin air gap, emitted on the surface of the deflector and directed rearward, in the direction of the scroll of the support.
• This air gap generates an air cushion which simultaneously separates the support from the deflector surface by modifying the flatness of said support and facilitates the scrolling of said support accompanying its movement.
• the deflector When the deflector is placed, for example, below the support, it is raised locally, and this deformation compensates for its transverse elongation, without contact. Such deformation can therefore have indifferently at the level of the unprinted and printed areas of the support.
• the blowing chamber is formed, transversely to the axis of travel of the printing medium, of two approximately parallel walls (or slightly diverging from one another in the direction of the printing medium), oriented in the direction of the rear of the deflector in the direction of travel of said support, the two walls being either concave upstream, the other convex downstream, or planar and oblique.
• the air gap is directed towards the rear of the deflector.
• the deflector is formed, in the direction of travel of the printing medium, with a front portion and a rear portion mounted on a sole, the rear face of the front portion and the front face of the rear portion forming the walls (for example respectively concave and convex) of the blowing chamber.
• the front part, the rear part and the sole of the deflector may consist of a single piece or several pieces. According to a preferred embodiment, the rear part of the deflector and the sole form a single piece.
• the front part of the deflector has an increasing thickness in the direction of travel of the printing medium
• the rear part has a thickness greater than the front part and comprises from front to rear an oblique leading edge or rounded and a flat surface approximately parallel to the scroll plane of the print medium.
• the rear face of the deflector is beveled or rounded, the surface facing the printing medium protruding from the surface to the contact the sole, directly above the plane of scroll of said support, so as not to cause the plating of the print medium in the immediate rear of the deflector.
• the rear part of the deflector has rounded longitudinal flanks.
• the air blowing chamber advantageously has a central position in the baffle; thus, the air gap is distributed over all the "active" surfaces of the rear part of the baffle so as to avoid contact with the printable medium, and consequently to avoid ink marks on non-contact areas. printed from said medium.
• the chamber further comprises longitudinal walls formed by inserts to also form shims for adjusting the spacing of the transverse walls between them.
• the thickness of the air gap can be increased or reduced by modifying said wedges.
• Said wedges also serve as a seal to prevent lateral leakage of the air flow.
• the deflectors are stationary, and can be fixed on transverse beams located near the scroll plane of the print medium.
• the present invention also relates to printing machines of the offset printing type or to gravure or flexographic printing including the device described above.
• the offset printing machine comprises at least one device for compensating the width variation of the print medium as described above, arranged downstream of at least one printing unit, so as to locally deform the printing medium in order to to compensate for the widening of the width of said support occurring during its printing in the upstream printing unit or groups.
• the printing machine of the gravure printing or flexographic printing type comprises at least one device for compensating the variation width of the print medium as described above, arranged upstream of at least one printing unit so as to locally deform the printing medium in order to anticipate and compensate for the narrowing of the width of said support, occurring, especially during its drying, downstream of the printing unit.
• Figure 1 is a longitudinal sectional view of the deflector of a compensation device according to a first embodiment of the invention.
• FIG. 2 is a cross-sectional view along AA of the deflector of FIG. 1.
• Figure 3 is a longitudinal sectional view of the deflector according to Figure 1 in the presence of the print medium.
• FIG. 4 is a front view of the deflector of FIG.
• Figure 5 is a partial perspective view of a baffle of the compensation device according to the invention.
• Figure 6 is a perspective view of a baffle of the compensation device according to the invention.
• Figure 7 is a diagram illustrating the positioning and action of the compensation device in a printing machine according to the invention.
• Figure 8 is a longitudinal sectional view of the deflector of a compensation device according to a second embodiment of the invention, in the presence of the print medium.
• each deflector 2 is formed of a sole 3 on which are mounted, in the direction D of the scroll of the paper web, respectively a front portion 4 and a rear portion 5 separated by a chamber 6 blowing air.
• a first variant of the invention see FIGS.
• the rear face of the front part 4 is of concave shape matching the convex shape of the front face of the rear part 5.
• the rear face of the front portion 4 and the front face of the rear portion 5 are flat and oblique (see Figure 8).
• these two faces slightly spaced apart from one another, form the transverse walls of the blast chamber 6. These two walls are approximately parallel and are oriented, as can be seen in FIGS. 1 and 3, in direction of the rear of the deflector 2 in the direction D of the scrolling of the strip 1 of paper support paper.
• Recesses 7 and 8 are respectively formed in the rear part 5 of the deflector 2 and in the sole 3 for the supply of compressed air to the blast chamber 6.
• the air blowing chamber 6 opens out at the surface (here upper surface) of the deflector 2 facing towards the strip 1 of paper and produces a flow of air in the form of an air slit inclined towards said strip 1 and oriented towards the rear of the deflector 2.
• the upper surface of the deflector is in the form of an upward slope terminated by a "plateau", the upward slope being formed by the upper surface 9 of the front portion 4 and the leading edge 10 of the portion rear 5 of the deflector 2.
• the rear portion 5 of the deflector terminates in a flat upper surface 11 forming "plate" approximately parallel to the plane of travel of the strip 1 of paper.
• the scrolling plane is here defined as the plane formed by the printing medium 1 between two successive printing units without intervention of the compensation device according to the invention.
• the rear portion 5 of the deflector 2 also has rounded longitudinal sides 12 receiving a fraction of the air gap to avoid contact with the printable medium.
• the rear face 13 of the deflector is further beveled, the flat upper surface 11 protruding, directly above the plane of travel of said strip, the surface 14 which is in contact with the soleplate 3.
• the rear face 13a of the deflector may be of rounded shape.
• shims Between the front portion 4 and the rear portion 5 of the baffle, are positioned parts 15, called shims, visible in Figure 5, to separate the two parts 4 and 5 from one another and forming the longitudinal walls of the blowing chamber 6 while serving as a seal of this chamber.
• an orifice 18 allowing its attachment to the end of the rod of a cylinder (not shown) pneumatic single effect, whose stroke is for example from 10 to 20 millimeters approximately, allowing move the deflector 2 vertically relative to the printable support 1.
• the deflector 2 also has, at the front end of its sole 3, an end orifice 17 allowing, by means of a screw 16, to fix a guide anti-rotation 21 which ensures the positioning of the deflector parallel to the axis X of scroll of the paper web 1.
• the printing medium here the strip 1 of paper
• the printing medium here the strip 1 of paper
• Its deformation is progressive in the longitudinal direction because it There is a tension of the paper web between the rolls of the successive printing units, but more accentuated in the transverse direction of the paper web (see Figure 4).
• the air cushion formed by the outgoing air space, in the upper part of the deflector 2 and on the rounded longitudinal sides 12, of the air blowing chamber 6 and the upstream air 19 sucked by effect venturi (and possibly to the downstream air 20 displaced by the flow of air arriving against the paper web) the deformation of said strip 1 is effected without contact with the upper surface of the deflector 2.
• the scroll of the strip of paper is easier.
• FIG. 7 schematizes the operation of an offset type printing machine, for example, in four-color process.
• the strip 1 of paper from a reel scrolls along the X axis passing successively in the printing groups G1, G2, G3 and G4, each affixing a color on said strip.
• This strip 1 of initial width paper LO has, after passing through the first printing unit G1, a width L10 greater than the width LO, the increase in width being induced by the hygrometric supply and the crushing between the rolls of the printing unit G1.
• a compensation device for this increase in width consisting of two baffles 2a, is arranged upstream of the input in the next printing unit G2 and reduces the width L10 to a width L20 close to LO.
• the width of the strip 1 of paper is increased again and has the value L30 which is reduced again by means of a pair of baffles 2b arranged upstream of the passage of the strip 1 in the next printing unit G3.
• the new width at the entrance of this group G3 is L40 which is approximately equal to the width L20.
• the width of the band is increased again and takes the value L50 which is in turn compensated by means of a new pair of deflectors 2c.
• the new width obtained is L60 close to the previous value L40, before the band 1 passes through the last group printing G4.
• each deflector 2, 2a, 2b or 2c on the strip 1 can be adjusted by raising or lowering the tube vertically. deflector. These adjustments can be made in particular to allow a better superposition of colors printed successively on the paper strip.
• the deflectors (2, 2a, 2b, 2c) come into action when the printing machine exceeds a certain threshold of revolutions per hour (for example 5000 revolutions / hour) by means of the opening of the pneumatic circuit. which simultaneously feeds the jack and the blast chamber 6 of the baffle; the cylinder then moves the deflector against the printable support 1 (which constitutes the working position) and the flow of compressed air (under a pressure of about 5 to 6 bar) is directed into the blowing chamber 6, then towards the printable medium by forming the air cushion described above.
• a certain threshold of revolutions per hour for example 5000 revolutions / hour
• the pneumatic circuit closes: the jack then moves the deflector (for example via a spring integrated in the jack ) due to the absence of pressure, and the air flow through the blowing chamber is interrupted: the deflector spaced apart from the printable medium is then in said rest position.
• the air flow is regulated by the shims 15 pre-positioned between the front part 4 and the rear part 5 of the deflector and by a pressure regulator (not shown) installed on the compressed air supply.
• each deflector on the printable support 1 can be carried out manually by the operator, or can be motorized and remotely controlled from the control panel of the machine. It can also be automated and managed by an automatic control system equipped with scanners or cameras, which positioning spots or color markers imposed on the form by the printer and printed on the paper tape. Such a system then constantly controls the positioning of the spots of the successive colors and corrects the defects of color superposition, by intervening on the engines which adapt the constraint of each deflector on the printable support, taking as a reference the color printed in the group G1.
• the deflector of the compensation device according to the invention has many advantages, in particular:
• the generally rounded shape of the upper surface of the deflector makes it possible not to hang the paper web, especially during slowing down and stopping the running of the strip 1, unlike conventional blowing nozzles which may at any time damage or to perforate the paper web, whose weight is, for economic reasons, increasingly thin.
• the compressed air consumption of the compensation device according to the invention is reduced compared with the pulsed air device of the prior art.
• the air flow being continuous according to the present invention, the sound level in operation is very small.
• the compensation device adapts to all flexible print media whether they are printed on their entire surface or not.
• the width of the active zone of a deflector is approximately between 140 and 220 mm 2 .
• the deflectors In staggered", that is to say on both sides of the scrolling printing medium and not more only one side of the paper web as shown in FIG. 7.
• the above example has been described for printing machines using an offset printing process but can also be applied to printing machines using gravure or flexographic printing processes.
• the (or) pairs of deflectors 2 are positioned upstream of each of the printing groups, so as to reduce the width of the print medium before entering said printing unit, in order to anticipate the shrinkage of the paper web occurring at the drying stations located downstream of each printing unit.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Registering, Tensioning, Guiding Webs, And Rollers Therefor (AREA)
• Supply, Installation And Extraction Of Printed Sheets Or Plates (AREA)
• Handling Of Sheets (AREA)
• Feeding Of Articles By Means Other Than Belts Or Rollers (AREA)
• Character Spaces And Line Spaces In Printers (AREA)
• Rotary Presses (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=37719434

Family Applications (1)

Country Status (8)

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Family Cites Families (5)

• 2006
  • 2006-09-04 FR FR0607714A patent/FR2905302B1/fr not_active Expired - Fee Related
• 2007
  • 2007-08-29 PL PL07823457T patent/PL2059393T3/pl unknown
  • 2007-08-29 AT AT07823457T patent/ATE454266T1/de not_active IP Right Cessation
  • 2007-08-29 DE DE602007004232T patent/DE602007004232D1/de active Active
  • 2007-08-29 EP EP07823457A patent/EP2059393B1/de not_active Not-in-force
  • 2007-08-29 ES ES07823457T patent/ES2340969T3/es active Active
  • 2007-08-29 US US12/439,737 patent/US8313260B2/en not_active Expired - Fee Related
  • 2007-08-29 WO PCT/FR2007/001412 patent/WO2008029013A1/fr active Application Filing

Non-Patent Citations (1)

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