Sheet-fed printing machine and printing unit in a sheet-fed printing machine

Patent metadata

Field	Value
Publication number	US-9770924-B2
Application number	US-201615133439-A
Country	US
Kind code	B2
Filing date	Apr 20, 2016
Priority date	Apr 20, 2015
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

A printing unit in a sheet-fed printing machine includes a printing cylinder, an upstream transfer cylinder and a downstream transfer cylinder. The transfer cylinders each include a device for decelerating/accelerating a sheet. The device, in particular, includes at least one gripper bar being movable in a substantially radial direction to change the tangential speed of the gripper bar and thus of the sheet. A printing unit of this construction allows the sheets to be transported at a lower speed and at a shorter distance from one another during the printing process, resulting in a better print quality and a higher throughput of the machine. A sheet-fed printing machine including such a printing unit is also provided.

First claim

The invention claimed is:

1. A printing unit in a sheet-fed printing machine, the printing unit comprising:
a printing cylinder;
a transfer cylinder disposed upstream of said printing cylinder in a sheet transport direction, said upstream transfer cylinder having a device for decelerating a sheet from a higher machine sheet speed to a lower printing sheet speed; and
a transfer cylinder disposed downstream of said printing cylinder in the sheet transport direction, said downstream transfer cylinder having a device for accelerating a sheet from the lower printing sheet speed to the higher machine sheet speed.

2. The printing unit according to claim 1 , wherein said device for decelerating a sheet and said device for accelerating a sheet each include at least one respective gripper bar being movable in a substantially radial direction.

3. The printing unit according to claim 2 , wherein said device for decelerating a sheet and said device for accelerating a sheet each include a respective cam mechanism for actuating said respective gripper bar.

4. The printing unit according to claim 2 , which further comprises at least one pivot joint supporting each respective gripper bar.

5. The printing unit according to claim 4 , wherein said at least one pivot joint is a four-bar linkage.

6. The printing unit according to claim 1 , wherein said device for decelerating a sheet and said device for accelerating a sheet each include a respective rotary drive for changing rotational speeds of a respective one of said transfer cylinders.

7. The printing unit according to claim 1 , wherein said device for decelerating a sheet and said device for accelerating a sheet each include a respective rocker with a respective gripper bar fixed thereto, said rockers each carrying out a movement relative to a respective one of said transfer cylinders.

8. The printing unit according to claim 1 , wherein said printing cylinder has a plurality of sheet-holding areas.

9. The printing unit according to claim 8 , wherein said printing cylinder is a 1/5-revolution cylinder with five of said sheet-holding areas.

10. The printing unit according to claim 8 , wherein each two respective sheet-holding areas have a respective gap there between.

11. A sheet-fed printing machine, comprising a printing unit according to claim 1 .

12. The sheet-fed printing machine according to claim 11 , wherein the printing machine is a digital printing machine.

13. The sheet-fed printing machine according to claim 12 , which further comprises inkjet heads spaced apart from said printing cylinder.

14. The printing unit according to claim 1 , wherein:
said device for decelerating a sheet decelerates a sheet already disposed on said upstream transfer cylinder; and
said device for accelerating a sheet accelerates a sheet already disposed on said downstream transfer cylinder.

15. The printing unit according to claim 1 , wherein:
said device for decelerating a sheet decelerates a tangential speed of a sheet while maintaining an angular speed of said upstream transfer cylinder; and
said device for accelerating a sheet accelerates a tangential speed of a sheet while maintaining an angular speed of said downstream transfer cylinder.

Assignees

• Heidelberger Druckmasch Ag

Inventors

• Mutschall Stefan

Classifications

• B41J13/03

  driven, e.g. feed rollers separate from platen · CPC title

• B41J11/04 Primary

  Roller platens · CPC title

• B41J11/24

  Detents, brakes, or couplings for feed rollers or platens · CPC title

• B41J13/0009

  control of the transport of the copy material · CPC title

• B41J13/00

  Devices or arrangements {of selective printing mechanisms, e.g. ink-jet printers or thermal printers,} specially adapted for supporting or handling copy material in short lengths, e.g. sheets · CPC title