Printing – Rolling contact machines – Rotary
Reexamination Certificate
1999-10-14
2002-03-05
Hilten, John S. (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S483000
Reexamination Certificate
active
06352027
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a printing machine with a finger protector and, more particularly, a finger protector that is formed as a blast tube.
Protective devices of this general type serve as protection for the hands in printing machines, and prevent the operator's hand from being pulled in between two cylinders if the operator should carelessly reach too far into the cylinder nip during cleaning or maintenance work.
German Patent 44 17 054, corresponding to U.S. Pat. No. 5,537,922, describes, by way of example, a proofing device in the printing unit of a printing machine. This multifunctional proofing device serves mainly as a guide element for printing plates and additionally as a finger protection and blasting device. The blasting or blowing function makes it possible to supply drying air to the cylinder surface of a rubber blanket cylinder at the end of a washing operation. The proofing device is arranged in a nip formed by a plate cylinder together with a rubber blanket cylinder, and therefore not in a nip formed by an impression cylinder together with an adjustable cylinder.
The published German Patent Document DE 43 18 777 C2 describes a device for assisting the guidance of sheets. As illustrated diagrammatically in this document, the blast tubes of this device do not extend over the entire cylinder width and have no finger protection function. On the contrary, the object upon which this device is based is to build up an air cushion between a sheet and a rubber blanket cylinder, on a printing unit that is not involved with printing and that has a nip between the rubber blanket cylinder and an impression cylinder. The device does not have an adjustable cylinder that is adjustable into a clearance position far removed from an impression cylinder. The build up of the air cushion is, of course, only possible when the clearance between the rubber blanket cylinder and the sheet-guiding impression cylinder is 2 millimeters, as specified, which is thus a very small clearance.
The published German Patent Document DE 690 22 419 T2, corresponding to U.S. Pat. No. 4,934,305, corresponding to the published European Patent Document EP 0 477 283 B1 describes a retractable coating device with a rubber blanket cylinder. The coating cylinder can be adjustable relative to an impression cylinder into an operating position for coating the printing-material sheet resting on the impression cylinder, into a cut-off position with a small clearance relative to the impression cylinder and into a position, designated as a second position, far removed from the impression cylinder and with good access to the coating cylinder for the purpose of maintenance or cleaning. There is no finger protector in this coating device.
The published German Patent Document DE 297 10252 U1 describes a guide arrangement for sheetlike printing material in a printing machine. The guide arrangement includes a guide tube that is preceded by a pivotably mounted pneumatic system and, for example, a blast tube extending over the entire width of a sheet guide cylinder. The guide plate can be coupled to a circuit-safeguarded protective device for protecting against hazardous locations in the region of the sheet guide cylinder. The guide arrangement includes, in addition to the guide plate described hereinabove, a further guide plate that is mounted so as to be pivotably movable and that is sensor-safeguarded which serves as a switching protective device if a person enters the region formed by the sheet guide cylinder. The two guide plates are assigned to sheet guide cylinders functioning as transfer drums between a printing unit and a varnishing unit. The transfer drums are not mounted so as to be capable of being thrown off or disengaged from one another, but, as is known, are mounted fixed in position location in the machine frame.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a printing machine that is safeguarded against risks of injury, that can be operated in a maintenance-friendly manner and operates with a smear-free sheet run. It is a further object of the invention to provide a method for operating a sheet-fed printing machine.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, in a printing machine, an improvement therein comprising a finger protector formed as a blast tube and arranged in a region of a wedgelike cylinder nip formed by an impression cylinder together with an adjustable cylinder, the adjustable cylinder being adjustable into a clearance position far removed from the impression cylinder.
In accordance with another feature of the invention, a minimum circumferential clearance of the cylinders relative to one another, when the adjustable cylinder is located in the far-removed clearance position, is equal to at least several centimeters and, in particular, several decimeters.
In accordance with a further feature of the invention, in a protective position protecting against entry into the cylinder nip, the finger protector is movably mounted and the position thereof is sensor-monitored.
In accordance with an added feature of the invention, the printing machine includes a sensor for monitoring the position of the finger protector, the sensor being responsive for stopping a drive for rotating the adjustable cylinder, when the finger protector is forced out of the protective position.
In accordance with an additional feature of the invention, the sensor is formed as an electric motor.
In accordance with yet another feature of the invention, the finger protector is forcible out of the protective position due to manual contact during cleaning of the adjustable cylinder.
In accordance with yet a further feature of the invention, the finger protector and the blast tube forming the finger protector, respectively, are able to be acted upon by blowing air and are functionable as a sheet guide element when the adjustable cylinder is adjusted to the far-removed clearance position.
In accordance with yet an added feature of the invention, the blast tube is connected to a compressed air source for supplying the blast tube with blast air having such a pressure level that jet pressure of blast air flowing out of blast orifices formed in the blast tube maintains a printing-material sheet, that is being transported past the finger protector by the impression cylinder, at a distance from the finger protector at least over most of the sheet length thereof.
In accordance with yet an additional feature of the invention, the blast air orifices formed in the blast tube are oriented, in the angular position thereof, in a manner that, due to the jet direction of the blast air jets impinging on the printing-material sheet, the sheet that is transported past the finger protector by the impression cylinder is maintained at a distance from the finger protector at least over most of the sheet length thereof.
In accordance with still another feature of the invention, the impression cylinder and the adjustable cylinder are components of a unit of the printing machine, the unit being arranged downline of at least one of a printing and a coating unit of the printing machine, as viewed in the sheet transport direction, and being capable of being placed selectively into an activated and into an inactivated state, the adjustable cylinder, in the inactivated state, being adjusted to the far-removed clearance position, and the blast tube, in the inactivated state, being acted upon by blast air.
In accordance with still a further feature of the invention, the unit is one of a printing, a coating and a finishing unit, respectively.
In accordance with still an added feature of the invention, the adjustable cylinder is adjustable into a throw-on position wherein it has operative contact with one of the impression cylinder and the printing-material sheet resting thereon, respectively, the adjustable cylinder being one of a cylinder for printing the printing-material sheet in the throw-on position,
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Hilten John S.
Lerner Herbert L.
Nguyen Anthony H.
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