Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F15/00—Screen printers
  • B41F15/08—Machines
  • B41F15/0804—Machines for printing sheets
  • B41F15/0809—Machines for printing sheets with cylindrical or belt-like screens

Definitions

• the invention relates to a method for printing decorations, in particular on substrates of variable dimensions, in particular made of glass.
• the printing process is of the kind in which the application of paint is provided with a rotary hollow cylinder-shaped stencil which presses and rolls against the substrate to be printed, the axial length of the stencil being greater than the maximum width of the substrates to print, the stencil being fed with paint or ink over its entire length, recovery means being provided downstream of the printing area to collect the paint which has not been transferred to the substrate.
• a squeegee may be placed inside the hollow cylinder to squeeze the paint into the lower area of the cylinder.
• Such a process is known from EP-A-0 874 458.
• the stencil comprises zones which are outside the contour of the substrate, in particular because of the variable dimensions of this substrate.
• the paint in these areas is not transferred to the substrate and is a surplus that can result in blurred images on the substrates that will follow.
• means for recovering the excess paint are provided in the form of a doctor blade located inside the stencil to transfer the excess paint on a disposal cylinder rolling outside against the stencil.
• the assembly is relatively bulky and the friction of the doctor blade against the stencil accelerates the wear of the equipment.
• EP-A-0 511 883 shows a screen printing process for printing a decorative layer on glazing according to which a flat screen screen having some degree of flexibility, is attached to a peripheral frame.
• the screen printing screen with the printing ink is applied against the glazing by a squeegee located on the side of the screen opposite the glazing.
• a squeegee attached to the squeegee and located on the side of the screen opposite the glazing to be printed, is provided to suck the excess ink.
• the nozzle is attached to the doctor blade and is moved along the screen. The nozzle is thus caused to pass over areas of the substrate that have been printed, which can affect the quality of printing.
• the choice of the location of the nozzle is limited since the latter is fixed to the doctor blade.
• the object of the invention is, above all, to provide a method for printing decorations on substrates which makes it possible to eliminate the excess paint on the rotary stencil under improved conditions, with reduced friction and under a space requirement.
• the process for printing decorations on substrates is characterized in that the recovery means comprise pneumatic extraction means arranged in the vicinity of the hollow cylinder and means for collecting the paint extracted.
• the pneumatic extraction means work by suction and are located either inside or outside the cylinder, as well as the means for collecting the extracted paint.
• blowing means which contribute to the separation of the paint residues and which are located on the opposite face of the cylinder, respectively outside and inside thereof.
• the suction means and the means for collecting the paint are located outside the cylinder.
• the position of the recovery means is independent of that of a squeegee placed inside the hollow cylinder for pressing the paint in the lower area of the cylinder.
• the recovery means are disposed in an angular zone which corresponds to three quarters of a circumference immediately downstream of the printing zone having for its starting point the doctor blade.
• the position of the recovery means in said zone depends on the viscosity of the paint used: a low viscosity allows a position remote from the doctor blade.
• the viscosity is high, it is advantageous to arrange the recovery means as close as possible to the doctor blade, preferably in the first quarter of the printing zone.
• the means for recovering the extracted paint are located at a level lower than that of the extraction zone of the paint so that the gravity favors the recovery of the paint.
• the pneumatic extraction means are disposed in an area below the horizontal plane passing through the axis of the cylinder, downstream of the printing zone.
• the invention also relates to a device for printing decorations, in particular on substrates of variable dimensions, in particular made of glass, comprising a rotary hollow cylinder-shaped stencil which presses and rolls against the substrate to be printed, the axial length of the stencil being greater than the maximum width of the substrate to be printed, the stencil being supplied with paint over its entire length, recovery means being provided downstream of the printing zone to collect the paint which has not been transferred onto the substrate , characterized in that the recovery means comprise pneumatic extraction means for extracting the paint remaining in areas of the stencil and means for collecting the extracted paint.
• Fig.l is a schematic vertical sectional view of a printing device according to the invention
• Fig.2 is a schematic plan view of the device of Fig.l. Referring to the drawing, there can be seen a device 1 for printing decorations on substrates 2, 2a of varying shapes and sizes.
• the substrates generally have a flat surface but may also have a curved surface having a small angle of curvature, less than about ten degrees, preferably less than a few degrees. By angle of curvature of the curved surface, it is necessary to understand the maximum angle that can be formed between two tangent planes at two different points of the surface.
• the substrates are preferably made of a material resistant to the treatment of transformation of the paint, which may be exposure under ultraviolet radiation (UV-crosslinkable paint) or firing, for example at a temperature of the order of 100 to 250 ° C. VS
• the substrates are in particular glass, but may be metal, ceramic or plastic, for example polycarbonate or polyacrylate.
• the device 1 comprises a rotary screen 3 in the form of a hollow cylinder 4, or drum, of geometric axis XX, provided with a rigid screen screen.
• the substrates 2, 2a are placed on a conveyor 5 which runs under the hollow cylinder 4 in the direction of the arrow A, that is to say from left to right according to FIG.
• the hollow cylinder 4 is mounted on a horizontal shaft 6 (Supported by means not shown) and is rotated in the direction of the arrow G (anticlockwise direction according to Fig.l) so as to roll without sliding against the substrate 2.
• the axial length L (Fig.2 ) of the stencil 3 is greater than the width (dimension parallel to the axis of the cylinder 4) m maximum of the substrate 2 to be printed, so that the impression of the decor can go to the longitudinal edges of the substrate 2.
• the stencil 3 is fed, inside the hollow cylinder 4, P paint over its entire length by means not shown.
• a doctor blade 7 is placed and held inside the hollow cylinder 4 to press the paint in the lower region of the hollow cylinder, substantially following the lower generatrix.
• the decor to be printed may consist of one or more plain patterns, for example in the form of flat (s) and / or repetition.
• the silkscreen screen which makes it possible to obtain the decoration is rigid and seamless, and may be composed of a perforated metal plate with the desired decoration, of a fabric formed of yarns made of an organic material, for example polyamide or a polyester, a metallized fabric, for example obtained by galvanizing the above-mentioned organic fabric, or a fabric of metal son.
• the length L of the hollow cylinder can be several meters, up to about 4 meters, preferably up to 3 meters.
• the circumference of the hollow cylinder may be greater than 1 meter, advantageously of the order of 1.5 meters.
• the print speed can be 7 to 8 meters per minute.
• the recovery means R are provided downstream of the printing zone I in the direction of rotation G of the hollow cylinder 4, to extract the paint remaining in the areas of the stencil 3 which are outside the substrate 2. In indeed, this paint has not been transferred to the substrate.
• the recovery means R extend all along the hollow cylinder 4.
• the recovery means R comprise pneumatic extraction means 8 in particular formed by a suction nozzle whose inlet 9 is situated in the vicinity of the hollow cylinder 4, this nozzle 8 being inclined downwards from the inlet 9.
• nozzle 8 is located below the horizontal plane H passing through the axis XX of the hollow cylinder, and is connected to a suction pipe T, itself connected to a vacuum source not shown.
• the recovery means further comprise means 10 for collecting the extracted paint.
• the means 10 are advantageously formed by a receptacle located in the extension of the nozzle 8, at a lower level.
• gravity acts essentially in the same direction as suction, which promotes the recovery of paint.
• a dispenser 11 of diluent liquid it is possible to install, at the inlet 9 of the nozzle, a dispenser 11 of diluent liquid to prevent too fast drying of the extracted paint.
• the means R may comprise a pressurized air blowing nozzle located inside the hollow cylinder 4 while the receptacle 10 is located outside the hollow cylinder in the extension of the substantially radial air jet. , directed downwards, coming from the nozzle.
• the recovery means R are preferably arranged in an angular zone which corresponds to the quarter of circumference situated immediately downstream of the printing zone I.
• the substrate 2 passing under the hollow cylinder 4 is printed, for example over its entire surface E.
• the paint located in the zones 4a, 4b of the hollow cylinder outside the outline of the substrate 2 is recovered by the suction nozzle 8, which avoids fuzzy impressions later due to excess paint.
• the excess paint does not remain exposed for a long time so that drying problems are limited, the risk of fouling of the screen is reduced.
• the device for recovering excess paint is compact.
• the power of recovery can easily be varied by acting on the suction power.
• the pneumatic recovery, particularly by suction can be done without direct contact by keeping the nozzle 8 at a small distance from the hollow cylinder 4 so as to minimize the wear of the screen printing screen. The lower the distance, the better the efficiency of the suction. Recovery is located away from the print area and does not act on this area.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Printing Methods (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Screen Printers (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=34945970

Family Applications (1)

Country Status (8)

Cited By (3)

Family Cites Families (6)

• 2004
  • 2004-06-04 FR FR0406139A patent/FR2871099B1/fr not_active Expired - Lifetime
• 2005
  • 2005-06-02 PT PT05776426T patent/PT1755893E/pt unknown
  • 2005-06-02 DE DE602005003357T patent/DE602005003357T2/de not_active Expired - Lifetime
  • 2005-06-02 ES ES05776426T patent/ES2297752T3/es not_active Expired - Lifetime
  • 2005-06-02 EP EP05776426A patent/EP1755893B1/de not_active Expired - Lifetime
  • 2005-06-02 PL PL05776426T patent/PL1755893T3/pl unknown
  • 2005-06-02 WO PCT/FR2005/050406 patent/WO2005123389A1/fr not_active Ceased
  • 2005-06-02 AT AT05776426T patent/ATE378176T1/de not_active IP Right Cessation

Non-Patent Citations (1)

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