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EP-3208565-B1 - AUTOMATIC EXHAUST AIR RECIRCULATION SYSTEM FOR A PRINTING MACHINE OF THE FLEXOGRAPHIC OR ROTARY TYPE, OR FOR A LAMINATING MACHINE

EP3208565B1EP 3208565 B1EP3208565 B1EP 3208565B1EP-3208565-B1

Inventors

  • Squicciarini, Stefano

Dates

Publication Date
20260513
Application Date
20170216

Claims (16)

  1. Automatic exhaust air recirculation system (10) for a drying oven (92) for a machine (90) that uses tare-based inks or glues and/or flammable solvent-based inks or glues, or their like, wherein said machine (90) is selected from a printing machine of the flexographic or rotary type, a laminating machine, a coating machine, said automatic exhausted air recirculation system (10) includes a plurality of air ducts for defining an air ventilation system (20) for said drying oven (92) for said machine (90), said plurality of air ducts comprises an air inlet duct (21), an exhausted air evacuation duct (23) and a exhaust air recirculation duct (24), wherein the automatic exhaust air recirculation system comprises an electronic control and command unit (15) and at least one temperature sensor (13) and an humidity sensor (12), in particular a relative humidity sensor (12), wherein said humidity sensor (12) and said temperature sensor (13) are associated with said plurality of air ducts for detecting the temperature and the air humidity and for determining the relative humidity and in particular the absolute humidity within said plurality of air ducts, also said electronic control and command unit (15) is connected to said humidity sensor (12) and connected to said temperature sensor (13) for recirculating at least partially the exhaust air within said plurality of air ducts, for reducing the energy consumption and for reducing the cubic meters of air to be evacuated, advantageously reducing the total cubic meters of exhaust air that may be treated prior to placing the same within an external environment, and at the same time for avoiding the condensation of water vapor on a product (94) and also at the same time preferably for maintaining the same quality of a second product (94) obtainable with no air circulation or with a fixed recirculation at minimum levels such as a recirculation of 20%, also said automatic exhaust air recirculation system (10) comprising ventilation means (32,35) and a plurality of dampers (31,33,34) with modulated opening which are inserted within said plurality of air ducts and also connected to said electronic control and command unit (15) for varying the air flow within said plurality of air ducts, said plurality of dampers comprising at least a first motorized damper (34) which is housed within said exhaust air recirculation duct (24) for varying the opening of the same, said plurality of dampers comprising at least a second motorized damper (31) which is housed within said air inlet duct (21) for varying the opening of the same, said plurality of dampers comprising at least a third motorized damper (33) which is housed within said exhaust air evacuation duct (23), and said electronic control and command unit (15) is connected to said first motorized damper (34), and to said second motorized damper (31), and to said third motorized damper (33), for varying the opening of the same.
  2. Automatic exhaust air recirculation system (10) according to claim 1, characterized in that said humidity sensor (12) is positioned externally to said plurality of air ducts, and in particular it is positioned externally to an exhaust air evacuation duct (23) or externally to an air inlet duct (21).
  3. Automatic exhaust air recirculation system (10) according to claim 1 or 2, characterized in that said plurality of air ducts comprises an air heating duct (22) for introducing conditioned air, preferably heated, into said drying oven (92) for said machine (90), in which said humidity sensor (12) is associated with said exhaust air evacuation duct (23), or to said air inlet duct (21).
  4. Automatic exhaust air recirculation system (10) according to any of the claims from 1 to 3, characterized in that said humidity sensor (12) is integrated with a temperature sensor (13) in just one humidity and temperature sensor (12,13) which is able to detect at the same time the temperature and the humidity of the air, in particular which is able to detect the temperature and the relative humidity of the air.
  5. Automatic exhaust air recirculation system (10) according to any of the claims from 1 to 4, characterized by comprising a concentration detecting device (40) for a flammable solvent, preferably of infrared (IR) type or a flame ionization type or catalytic, which is connected to said electronic control and command unit (15) for detecting a concentration of said flammable solvent and for obtaining a ration, preferably percentage, between a concentration of said flammable solvent to a predetermined time instant and a predetermined minimum critical concentration of said flammable solvent which would lead to a risk of fire or explosion.
  6. Automatic exhaust air recirculation system according to any of the claims from 1 to 5, characterized by comprising air sampling means (50) which are associated with said plurality of air ducts for taking a sample of air from said plurality of air ducts and for detecting the humidity of the sampled air by said humidity sensor (12), and in particular for detecting the humidity and air temperature of the sampled air by said humidity sensor and temperature (12,13).
  7. Automatic exhaust air recirculation system according to claim 6, characterized by comprising exclusion means (60) for said sampling means (50) which are positioned between said plurality of air ducts and said sampling means (50) for avoiding a contact of said humidity sensor (12), and in particular of said humidity sensor and temperature (12,13), with any flammable solvents present in said air sample in particular during a process where are used flammable solvent-based pigments or glues, or their like.
  8. Automatic exhaust air recirculation system according to claim 6, characterized in that said sampling means (50) and said exclusion means (60) are both connected to said electronic control and command unit (15); in particular in the case of a detection of at least one solvent within said plurality of air ducts with a concentration higher respect to a predetermined minimum concentration, which for example equal to or less than 3% of the LEL that is the minimum critical concentration limit of the solvent that would lead to a risk of explosion or fire, said electronic control and command unit (15) enables an actuator of said exclusion means (60) for said sampling means (50) for isolating and separating said sampling means (50) from said plurality of air ducts, avoiding that said humidity sensor (12), and in particular that said humidity and temperature sensor (12,13), come into contact with air in which is present a solvent.
  9. Automatic exhaust air recirculation system according to any of the claims from 6 to 8, characterized in that said sampling means (50) comprise a chamber (52) within which is partially inserted said humidity sensor (12) and in particular said humidity and temperature sensor (12,13), in particular said chamber (52) is connected to said exhaust air evacuation duct (23) or to said air inlet duct (21).
  10. Automatic exhaust air recirculation system according to any of the claims from 6 to 9, characterized in that said sampling means (50) comprise a isokinetic probe (54) which is associated with said plurality of air ducts for said machine (90), and in particular said isokinetic probe (54) is partially inserted within said exhaust air evacuation duct (23) or within said air inlet duct (21) for picking up an homogeneous and uniform sample of air within said plurality of air ducts, moreover said chamber (52) which is preferably associated with said isokinetic probe (54) in particular through a duct, also said sampling means (50) comprise air suction means, in particular of Venturi type, for sucking said air from said plurality of air ducts.
  11. Automatic exhaust air recirculation system according to any of the claims from 7 to 10, characterized in that said exclusion means (60) includes a non-return valve (62) to depression, which includes a first end and a second end, in particular said first end of said non-return valve is connected to said isokinetic probe (54) and said second end of said non-return valve is associated with, and in particular connected to, said chamber (52) preferably by means of a duct.
  12. Automatic exhaust air recirculation system according to any of the claims from 10 to 11, characterized in that said air suction means comprise air compression means for creating a flow of compressed air, and also said air suction means comprise a Venturi tube (56) connected at a first end to said chamber (52) and at a second end to said air compression means, also preferably said air suction means comprise an electrovalve which is positioned in a safe area which is external to the areas classified ATEX, which allows an interruption of said flow of compressed air into said Venturi tube (56), said electrovalve is also connected to said electronic control and command unit (15), and in particular a closing of said electrovalve determines a consequent automatic closing of said non-return valve (62).
  13. Automatic exhaust air recirculation system according to any of the claims from 10 to 11, characterized in that said chamber (52) is connected to said isokinetic probe (54) through said non-return valve (62) for avoiding that within said chamber (52) may enter an amount of solvent which would certainly irreversibly damage said humidity sensor (12) or said humidity and temperature sensor (12,13).
  14. Automatic exhaust air recirculation system according to any of the claims from 1 to 13, characterized in that said humidity sensor (12), and in particular said humidity and temperature sensor (12.13), it is an ATEX type sensor that is explosion-proof for use in environments with risk of explosion.
  15. Automatic exhaust air recirculation system according to any of the claims from 1 to 14, characterized in that said flammable solvents are selected from ethyl acetate, ethyl alcohol, isotropic alcohol, acetone, methyl ketone, hexane, toluene, methoxy propanol, ethoxy propanol, or their similar.
  16. Automatic exhaust air recirculation system according to any of the claims from 1 to 15, characterized by comprising a detecting device for a plurality of operating parameters of said machine (90), in particular for detecting, for example, the process speed that is the material advance speed, the operating temperature inside the drying ovens, the feed speed of the material to be printed or to be coupled or to be laminated, the width of said material, the air temperature within said drying oven.

Description

The present invention refers to an automatic exhaust air recirculation system for a printing machine of the flexographic or rotary type, or for a laminating machine, wherein said machine uses water-based inks or glues and/or flammable solvent-based inks or glues. In particular the present invention refers to an automatic air recirculation system for a drying station for a machine choice between a printing machine of the flexographic or rotary type, a laminating machine wherein said machine using water-based inks or glues and/or flammable solvent-based inks or glues. JPH0214772 A discloses a drying system for drying a coating liquid applied to a web. All coating machines, laminating machines or printing machine (rotogravure or flexographic) are equipped with the drying ovens; the purpose of these drying ovens is to evaporate the solvent or water from the surfaces of the materials during their working processes. The fresh air, taken outside or inside of the productive areas, is heated by suitable heating systems in order to obtain the desired drying temperature, which is subsequently pushed inside of the drying furnace and then be sucked and sent to evacuation. During solvent-based applications, the presence of solvents is detected through an analytical sensor capable of detect the solvents concentration. At high temperatures, solvents can create an explosion hazard, therefore the main objective of this analytical sensor is to monitor the solvent concentration for safety reasons. A purpose of the present invention is to provide an automatic exhaust air recirculation system for a printing machine of the flexographic or rotary type, or for a laminating machine which allows to reduce the energy consumption and at the same time which allows a high degree of safety both for water-based inks or glues than for flammable solvents-based inks or glues. Another purpose is to realize an automatic exhaust air recirculation system for a printing machine of the flexographic or rotary type, or for a laminating machine which allows to control and to reduce energy consumption and that the same time allows to use water-based inks or glues and also flammable solvent-based inks or glues. Still another purpose is to have an automatic exhaust air recirculation system for a printing machine of the flexographic or rotary type, or for a laminating machine which allows to reduce the energy consumption by using water-based inks or glues and/or flammable solvent-based inks or glues. A further purpose is to have an automatic exhaust air recirculation system for a printing machine of the flexographic or rotary type, or for a laminating machine which is economically advantageous. These purposes according to the present invention are achieved by realizing an automatic exhaust air recirculation system for a printing machine of the flexographic or rotary type, or for a laminating machine as described in claim 1. Additional features of the invention are highlighted by the following claims. The features and advantages of an automatic exhaust air recirculation system for a printing machine of the flexographic or rotary type, or for a laminating machine according to the present invention will become more evident from the following exemplifying and not for limiting description, referred to the attached schematic drawings in which: Figure 1 is a schematic view of an automatic air recirculation system according to the present invention;Figure 2 is a schematic view of a detail of Fig. 1;Figure 3 is a schematic view of Fig. 1 that shows the temperatures within the ventilation system of the automatic air recirculation system. With reference to the figures, according to the present invention, it is shown an automatic exhaust air recirculation system 10 for a drying station or oven 92 for a machine 90 which uses water-based inks or glues and/or flammable solvent-based inks or glues, or their similar, such as ethyl acetate, ethyl alcohol, isotropic alcohol, acetone, methyl ketone, hexane, toluene, methoxy propanol, ethoxy propanol, wherein in particular said machine 90 is selected from a printing machine of the flexographic or rotary type, a laminating machine, a coating machine. In particular said automatic exhaust air recirculation system 10 is suitable for a drying oven for a machine 90, in particular of the type previously described, which use water-based inks and/or flammable solvent-based inks or glues, or their similar, which for example ethyl acetate, ethyl alcohol, isopropyl alcohol, acetone, methyl ketone, hexane, toluene, methoxy propanol, ethoxy propanol. In particular said automatic exhaust air recirculation system 10 is suitable to be used for a drying station 92 for said machine 90, in particular for continuous production of products 94 preferably in the form of sheets or films of the type containing water-based glues or pigments or flammable solvent-based glues or pigments which become dried products 95 after being treated by said station o