Air delivery device for printing and coating applications

Abstract

An air delivery device and printing or coating machinery using the same. In one configuration, the air delivery device is an air knife that cooperates with a printing device such as a printing press, coating machine or the like. In a particular configuration, the air knife is situated adjacent a set of cylinders in the printing device such that upon a sheet or related piece of printed substrate being put in an air flowpath created by the air knife, one or more operations can be performed on the still wet printed or coated sheet to minimize the chance of contact of the wet sheet surface with sheet delivery or related components. Examples of such operations may include turning, bending or folding the sheet, as well as drying the ink or coating placed on the sheet by the printing machinery.

1 . In combination with a printing or coating machine possessive of a plurality of printing cylinders and delivery means for withdrawing printed or coated sheets from the printing cylinders, an air knife for preventing the sheets from contacting components making up the delivery means of the machine while the sheets are still wet, said air knife comprising:
 a housing comprising a plenum with an air inlet and an air outlet formed therein, said housing comprising at least one convex surface thereon;   a fairing configured to cover said air outlet and spaced relative thereto such that a gap formed between them permits air passing through said air outlet to be discharged through said gap and along said at least one convex surface; and   means for varying the thickness of said gap such that upon passage of a flow of air from said plenum and discharge through said gap, the fairing cooperates with said at least one convex surface to provide a Coanda effect on the discharged flow, said fairing and said at least one convex surface further aerodynamically cooperative with one another such that the Coanda effect imparted to the discharged flow further entrains at least a portion of ambient air surrounding at least one of said housing and said fairing such that said discharged flow and said entrained ambient air flow substantially together in a generally sheet-like pattern.   
     
     
         2 . The air knife of  claim 1 , further comprising means for changing the angular orientation of said air knife relative to the machine. 
     
     
         3 . The air knife of  claim 1 , wherein said means for varying the thickness of said gap comprises a sheet of material placed between opposing surfaces of said fairing and said housing. 
     
     
         4 . The air knife of  claim 3 , wherein said sheet of material includes at least one flow channel formed therein such that said passage of a flow of air from said plenum and discharge through said gap takes place through said flow channel. 
     
     
         5 . The air knife of  claim 4 , wherein said sheet of material comprises mylar. 
     
     
         6 . A delivery system for a printing device with rotatable printing cylinders, said delivery system comprising:
 a plurality of drive wheels at least one of which is rotatably mountable adjacent the rotatable printing cylinders;   a conveyor coupled to said plurality of drive wheels and responsive thereto;   at least one gripper bar coupled to said conveyor, said at least one gripper bar comprising at least one gripper thereon such that upon receipt of a sheet from the rotatable printing cylinders, said at least one gripper engages the sheet so that said conveyor transports the sheet from a first end of said delivery system adjacent the rotatable printing cylinders to a second end away from the rotatable printing cylinders; and   an air knife fluidly coupled to said first end of said delivery system, said air knife comprising:
 a housing comprising a plenum with an air inlet and an air outlet formed therein, said housing comprising at least one convex surface thereon; 
 a fairing configured to cover said air outlet and spaced relative thereto such that a gap formed between them permits air passing through said air outlet to be discharged through said gap and along said at least one convex surface; and 
 means for varying the thickness of said gap such that upon passage of a flow of air from said plenum and discharge through said gap, the fairing cooperates with said at least one convex surface to provide a Coanda effect on the discharged flow, said fairing and said at least one convex surface further aerodynamically cooperative with one another such that the Coanda effect imparted to the discharged flow further entrains at least a portion of ambient air surrounding at least one of said housing and said fairing such that said discharged flow and said entrained ambient air flow substantially together in a generally sheet-like pattern. 
   
     
     
         7 . The delivery system of  claim 6 , wherein said plurality of a plurality of drive wheels are rigidly coupled to one another with a rotating shaft that extends between them, said rigidly coupled plurality of drive wheels defining a delivery path that is substantially the same width as the adjacent rotatable printing cylinders, and wherein said air knife is disposed relative to said rotating shaft such that upon discharge of said generally sheet-like pattern of air from said air knife, the sheet that is engaged by said at least one gripper avoids contact with said rotating shaft. 
     
     
         8 . The delivery system of  claim 6 , further comprising an air regulator for varying the amount of flow of air entering into said plenum. 
     
     
         9 . The delivery system of  claim 8 , further comprising a switching mechanism cooperative therewith to selectively operate said air discharged through said gap. 
     
     
         10 . The delivery system of  claim 9 , wherein said switching mechanism comprises:
 at least one sensor placed in signal communication with at least one of said plurality of drive wheels, conveyor and at least one gripper bar; and   a controller signally responsive to said at least one sensor such that upon receipt of a control signal therefrom, said controller selectively enables or disables a supply of air to said air knife.   
     
     
         11 . A printing device comprising:
 a sheet feeder station;   a sheet receiving station;   a sheet delivery station operatively situated between said sheet feeder and said sheet receiving stations, said sheet delivery station comprising:
 a plurality of drive wheels; 
 a conveyor coupled to said plurality of drive wheels and responsive thereto; and 
 at least one gripper bar coupled to said conveyor, said at least one gripper bar comprising at least one gripper configured to engage the sheet so that said conveyor transports the sheet from a first end of said delivery station to a second end; 
   a printing station comprising a plurality of rotatable cylinders for imparting at least one of a printing and a coating to the sheet, said printing station configured to cooperate with said sheet feeder station and said sheet delivery station to deliver a printed sheet to said sheet delivery station; and   an air knife fluidly coupled to said first end of said delivery system, said air knife comprising:
 a housing comprising a plenum with an air inlet and an air outlet formed therein, said housing comprising at least one convex surface thereon; 
 a fairing configured to cover said air outlet and spaced relative thereto such that a gap formed between them permits air passing through said air outlet to be discharged through said gap and along said at least one convex surface; and 
 means for varying the thickness of said gap such that upon passage of a flow of air from said plenum and discharge through said gap, the fairing cooperates with said at least one convex surface to provide a Coanda effect on the discharged flow, said fairing and said at least one convex surface further aerodynamically cooperative with one another such that the Coanda effect imparted to the discharged flow further entrains at least a portion of ambient air surrounding at least one of said housing and said fairing such that said discharged flow and said entrained ambient air flow substantially together in a generally sheet-like pattern toward said printing station. 
   
     
     
         12 . The printing device of  claim 11 , wherein said printing device comprises a printing press. 
     
     
         13 . The printing device of  claim 11 , wherein said printing device comprises a coating machine. 
     
     
         14 . The printing device of  claim 11 , wherein said conveyor comprises an endless conveyor. 
     
     
         15 . The printing device of  claim 11 , further comprising a device coupled to said air knife such that the angular orientation of said generally sheet-like pattern of air flow being directed toward said printing station can be varied. 
     
     
         16 . A method for supporting and conveying a wet sheet which has been discharged from a printing device, said method comprising:
 receiving said sheet from at least one rotatable printing cylinder;   transporting said sheet away from said at least one rotatable printing cylinder with a delivery system such that an air knife cooperative with said delivery system imparts an airflow to said sheet so that said sheet avoids contact substantially from the time it leaves the at least one rotatable printing cylinder until said sheet is engaged by at least one gripper on said delivery system, said air knife comprising:
 a housing comprising a plenum with an air inlet and an air outlet formed therein, said housing comprising at least one convex surface thereon; 
 a fairing configured to cover said air outlet and spaced relative thereto such that a gap formed between them permits air passing through said air outlet to be discharged through said gap and along said at least one convex surface; and 
 means for varying the thickness of said gap such that upon passage of a flow of air from said plenum and discharge through said gap, the fairing cooperates with said at least one convex surface to provide a Coanda effect on the discharged flow, said fairing and said at least one convex surface further aerodynamically cooperative with one another such that the Coanda effect imparted to the discharged flow further entrains at least a portion of ambient air surrounding at least one of said housing and said fairing such that said discharged flow and said entrained ambient air flow substantially together in a generally sheet-like pattern; and 
   delivering a source of pressurized air to said sheet through said air knife.   
     
     
         17 . The method of  claim 16 , further comprising varying the thickness of said gap such that said generally sheet-like pattern of airflow being delivered by said air knife is optimized for a particular sheet. 
     
     
         18 . The method of  claim 16 , further comprising varying the angular orientation of said air knife relative to said sheet through a pivotal mounting of said air knife. 
     
     
         19 . The method of  claim 16 , further comprising varying the linear placement of said air knife along said delivery device. 
     
     
         20 . The method of  claim 19 , wherein said varying the linear placement of said air knife along said delivery device is through a linearly adjustable mounting bracket. 
     
     
         21 . The method of  claim 16 , wherein said delivery system comprises an endless conveyor cooperative with the at least one rotatable printing cylinder. 
     
     
         22 . The method of  claim 16 , further comprising varying the amount of flow of air entering into said plenum through operation of an air regulator. 
     
     
         23 . The method of  claim 16 , further comprising operating a switching mechanism to selectively operate an air source used to provide air to said air knife.