Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F21/00—Devices for conveying sheets through printing apparatus or machines
  • B41F21/10—Combinations of transfer drums and grippers

Definitions

• the invention relates to a printing cylinder of a sheet-fed printing machine, which has at least one cylinder pit in which sheet grippers are arranged.
• Printing cylinders of this type have been known for a long time, in particular in indirectly printing printing units such as offset printing presses (for example GB patent specification 1138369), in directly printing printing units such as intaglio printing machines and also in screen printing machines.
• the previously known printing cylinders have pressure saddles separated by cylinder pits, the circumferential length of the pressure saddle being adapted to the sheets to be printed and the cylinder pits lying in between are required to accommodate the sheet grippers.
• This screen printing stencil is acted upon by a squeegee on the inside of the printing nip, which accumulates the ink bead required for the printing process in front of the printing nip.
• the screen printing template When passing through a cylinder pit of the printing cylinder, the screen printing template can no longer be supported on the circumference of the printing cylinder and is more or less pressed into the cylinder pit under the effect of the doctor blade pressure, as a result of which it can be damaged.
• the present invention is based on the object of designing a printing cylinder of a sheet-fed printing press in such a way that the effects and disadvantages associated with the presence of cylinder pits are avoided in a simple manner during the printing process.
• the printing cylinder according to the invention is characterized in that the sheet grippers in their closed position do not protrude beyond the envelope of the cylindrical circumferential surface of the printing cylinder and that each cylinder pit is provided with a cover which can be adjusted by an adjusting mechanism which, in a first position, Completely covers the cylinder pit with the grippers located in its closed position and supplements the cylindrical peripheral surface of the pressure cylinder and which, in a second position, at least partially releases the cylinder pit in the area of the grippers.
• the printing cylinder with its adjusting mechanism can be designed such that a cylinder pit is completely closed each time it passes through the printing nip during the printing operation, but is released so far from the cover during the sheet transfer to and from the printing cylinder that the grippers are released can take their open position and the sheet transfer can take place in the usual way. If transfer cylinders with sheet grippers are provided for sheet transfer to and from the printing cylinder, then a cylinder pit of the printing cylinder is opened so far during sheet transfer that the sheet grippers of the transfer cylinder in question can, as usual, dip somewhat into this cylinder pit.
• the printing cylinder continuously rolls on the image-printing cylinder during the printing operation with a closed, practically continuous surface, which can in particular be a screen printing cylinder of a screen printing machine or a rubber cylinder of an offset printing machine.
• the printing cylinder according to the invention can also be used in an embossing printing machine.
• the structure and surface of the printing cylinder and its printing saddle are each adapted to the type of printing press.
• the hard or sufficiently rigid surface of the cover preferably corresponds to that of the printing cylinder.
• Figure 1 shows a printing cylinder cooperating with a screen printing cylinder according to the invention in the relative position in which a partially open cylinder pit is located about a quarter of a turn in front of the printing nip, both cylinders being shown only partially.
• FIG. 2 shows the two cylinders according to FIG. 1 in the position in which the completely closed cylinder pit has just passed the pressure gap.
• a pressure cylinder 1 acts with a Screen printing cylinder 2 together, the circumference of which is formed by a cylindrical, elastic screen printing stencil 2a and the interior of which is indicated by the ink bead 2c accumulated by a doctor blade 2b. Both cylinders, which rotate in the direction of the arrows, form between them the printing nip through which the sheets B are passed by the printing cylinder 1 for the purpose of printing.
• the pressure cylinder 1 has only one cylinder pit 3 and therefore only one pressure saddle for receiving an arc B.
• the pressure cylinder can also have two or more evenly distributed cylinder pits and pressure saddle for receiving two or more arcs, all of the cylinder pits being of the same design .
• adjustable bow grippers 4 are mounted, which are adjustable in a known manner between an open position (FIG. 1) in which the gripper edges 4a project somewhat beyond the cylinder circumference and a closed position (FIG. 2) in which the grippers 4 do not protrude the circumference of the cylinder.
• FIG. 1 In the closed position, the grippers 4, with their gripper edges 4a, print the front edge of a sheet B against a gripper support 6, which, starting from the circumferential surface of the printing cylinder, is inclined somewhat inwards.
• the cylinder pit is also provided with an adjustable cover 7 which is adjustable about a shaft 8 between a closed position (FIG. 2) and an opening position partially releasing the cylinder pit (FIG. 1).
• the adjusting mechanism consists of a control lever in the form an angle lever 9, one end of which is fixedly connected to the cover 7 in the area of the shaft 8 and the other end of which carries a cam roller 10, from a stationary control cam 11 which, when the pressure cylinder 1 rotates, the cam roller 10 and thus the angle lever 9 with the Cover 7 leads, and from a the angle lever 9 with its cam roller 10 against the circumference of the cam 11 printing spring 12 which is attached to the rotating pressure cylinder 1.
• the control cam 11 has a circumferential region 11a concentric to the axis of the printing cylinder 1 and two outwardly projecting circumferential regions, which are located in the areas of sheet transfer to the printing cylinder and the sheet transfer from the printing cylinder and of which in the figures only the outwardly curved circumferential region Ilb im Area of the sheet transfer can be seen.
• the arrangement is such that the cover 7 closes the cylinder pit 3 completely as long as the cam roller 10 rolls on the peripheral region 11a of the control cam 11, and the cover 7 is partially opened when the cam roller 10 moves the outwardly curved peripheral regions 11b of the control cam 11 happens.
• the cover 7 is thus opened by partially opening it in the side where the grippers 4 are arranged.
• the cover 7 is curved in exactly the same way as the printing cylinder surface, so that in its closed position (FIG. 2) the printing cylinder 1 has a continuously closed surface.
• the material of the cover 7 corresponds to the material of the printing cylinder surface and therefore has the same Hard like this; in the example considered, it is preferably a metallic material.
• an elastic support 13 is attached to the side of the cylinder pit 3 facing away from the sheet grippers 4, as an extension of the circumferential surface of the cylinder. on the underside of which there is a somewhat inwardly displaced end piece 7a of the cover 7 in the closed position, as shown in FIG.
• the cover 7 is therefore adjusted as follows during the printing operation:
• the cover 7, as shown in FIG. 1 is partially opened so far that the sheet grippers 4 take their open position and the sheet grippers of the transfer cylinder, which hold the front edge of the sheet, can plunge sufficiently into the cylinder pit 3.
• these grippers are adjusted to their closed position in a known manner, as a result of which the sheet edge released by the grippers of the transfer cylinder is clamped between the gripper edges 4a and the gripper support 6.
• the cam roller 10 reaches the peripheral zone 11a of the control cam 11 and thereby causes the cover 7 to be closed, which completely covers the cylinder pit with the closed sheet grippers 4.
• the end of the cover 7 lying above the grippers 4 overlaps the leading edge of the sheet.
• the rigid cover 7 passes the printing nip (FIG. 2), serving as a fixed support for the squeegee 2b printing against the screen printing stencil 2a, so that the screen printing stencil cannot be damaged. It is therefore not necessary to lift the squeegee.
• the closed cover 7 has just passed completely through the printing nip, and printing on the sheet B begins.
• the cam roller 10 in the area of the sheet transfer, then rolls on the not shown area corresponding to the curved area 11b of the control curve 11, the cover 7 returns to its open position, so that the sheet gripper 4 can open and release the sheet edge, which of the transfer device transporting the sheet further, in particular a transfer cylinder with sheet grippers, is taken over.
• the cover 7 assumes its opening position only in the area of the sheet transfer and the sheet transfer.
• the arrangement can also be made so that the opening position between the transfer of a printed sheet and the transfer of an incoming sheet is maintained. It is essential that the Cover 7 assumes its closed position while a cylinder pit passes the pressure gap.
• the shock excitation is eliminated when printing, which not only avoids impairment of the printing quality, but also higher printing speeds than previously can be achieved.
• the invention is not limited to the exemplary embodiment described, but includes various other possibilities, in particular with regard to the adjusting mechanism.

Landscapes

• Supply, Installation And Extraction Of Printed Sheets Or Plates (AREA)
• Screen Printers (AREA)
• Making Paper Articles (AREA)
• Feeding Of Articles By Means Other Than Belts Or Rollers (AREA)
• Containers And Plastic Fillers For Packaging (AREA)
• Soil Working Implements (AREA)

Applications Claiming Priority (4)

Publications (2)

Family

ID=4186824

Family Applications (1)

Country Status (12)

Families Citing this family (29)

Family Cites Families (12)

• 1997
  • 1997-02-18 AT AT97902144T patent/ATE187928T1/de active
  • 1997-02-18 DE DE59700889T patent/DE59700889D1/de not_active Expired - Lifetime
  • 1997-02-18 WO PCT/CH1997/000061 patent/WO1997029912A1/fr not_active Ceased
  • 1997-02-18 CN CN97192386A patent/CN1097511C/zh not_active Expired - Fee Related
  • 1997-02-18 US US09/117,856 patent/US5960716A/en not_active Expired - Lifetime
  • 1997-02-18 JP JP52885997A patent/JP4023629B2/ja not_active Expired - Fee Related
  • 1997-02-18 UA UA98094903A patent/UA53644C2/uk unknown
  • 1997-02-18 AU AU15881/97A patent/AU713139B2/en not_active Ceased
  • 1997-02-18 RU RU98117468/12A patent/RU2170177C2/ru not_active IP Right Cessation
  • 1997-02-18 CA CA002241973A patent/CA2241973C/fr not_active Expired - Fee Related
  • 1997-02-18 EP EP97902144A patent/EP0883493B1/fr not_active Expired - Lifetime
  • 1997-02-18 KR KR10-1998-0706199A patent/KR100438111B1/ko not_active Expired - Fee Related

Non-Patent Citations (1)

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