JPH04275150A - Sheet by-blow stopper on impression cylinder of sheet counting rotary offset press - Google Patents

Abstract

PURPOSE: To provide a further improved apparatus for smoothing a sheet to perform printing certainty without doubling or printing blur even in the case of a high printing speed by effectively bringing a printing sheet in an overall width into contact with a periphery of an impression cylinder before entering a printing gap irrespective of a sheet quality. CONSTITUTION: Both ends of a blowing nozzle 8 are deviated in a feeding direction of a sheet 1 as compared with a central section of the nozzle. The nozzle is constituted to generate a smoothing operation of the sheet 1 from a midpoint of the sheet as a starting point of the sheet toward both outside edges from a leading edge of the sheet to a trailing edge of the sheet.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention provides a means for pressing sheets of paper onto the impression cylinder by the force action of flowing air, which is orientable towards the circumference of the impression cylinder and extends over a large part of the width of the impression cylinder. A blow nozzle is supported in front of the printing gap at a distance from the printing gap so that it can oscillate about an oscillation axis that is parallel to the impression cylinder axis, and the blow nozzle is oscillated in accordance with the working cycle of the printing machine. The printing sheet is smoothed on the impression cylinder before the printing gap of a rotary sheet-fed offset printing machine, in which the nozzle can be connected to a drive device that swings the nozzle back and forth in the running direction of the printing sheet. This invention relates to a device for preventing sheet tilting for contact.

0002

[Prior Art] The present invention is directed to European Patent Application No. 03066
In the device disclosed in German Patent Application No. 3920730.7, which takes as its starting point the prior art described in Specification No. The air-supplied blow nozzle ensures a reliable and thorough contact of the printed sheet with the impression cylinder periphery before entering the printing gap and print reliability without doubling or blurring even at high printing speeds. Techniques have been disclosed that attempt to further improve this. Sword-type blow nozzles are suitable for this purpose, which extend over a large part of the width of the impression cylinder, particularly preferably over the entire width of the impression cylinder. As a result, blowing air is applied to the printing sheet in a non-contact manner in order to bring the sheet into reliable and smooth contact with the impression cylinder periphery before entering the printing gap.

0003

Problems to be Solved by the Invention The problems to be solved by the present invention are as described in the above-mentioned Patent Application Publication No. 3 of the Federal Republic of Germany, regardless of paper quality.
Similar to the problem set in No. 920730.7, it is necessary to ensure that the printed sheet is in contact with the impression cylinder circumferential surface over its entire width before entering the printing gap, and to prevent doubling and blurring even at high printing speeds. It is an object of the present invention to provide a sheet-sheet tilting prevention device which is further improved so as to increase printing reliability.

0004

[Means for Solving the Problems] The structural means of the present invention for solving the above-mentioned problems is such that both ends of the blow nozzle are offset in the sheet running direction with respect to the central area of the blow nozzle, and , the blowing nozzle starts from the midpoint of the sheet and blows the sheet from the leading edge of the sheet toward the trailing edge of the sheet, and at the same time from the midpoint of the sheet toward both outer edges to stop the sheet from swinging. The point is that it is constructed in such a way that it produces an effect.

With this configuration, the airflow ejected from the blow nozzle leads in the direction of sheet travel at the midpoint of the sheet, so that the anti-tilt movement caused by the airflow moves from the leading edge of the sheet to the sheet. This occurs not only in the direction towards the trailing edge, but also outwardly on both sides from the midpoint of the sheet.

[0006] This effect can be achieved by means of a blowing nozzle shaped in the form of an arc, ie the blowing air ejected from the blowing nozzle first reaches the leading edge of the sheet and then moves towards the trailing edge of the sheet. At the same time, the sheet is smoothed outwards on both sides while being prevented from being tilted. In a preferred embodiment of the invention, the blowing nozzle has the shape of an arrowhead with its tip oriented in a direction opposite to the direction of travel of the sheet.

[0007]

Embodiments Next, embodiments of the present invention will be explained in detail based on the drawings.

Federal Republic of Germany Patent Application No. 3920
730.7, the printed sheet 1 taken off from a preceding printing unit is transferred by means of a transport drum 2 to the impression cylinder 3 of the following printing unit. A sheet gripper 4 grips the printed sheet 1 at a tangential point between the transport drum 2 and the impression cylinder 3 and moves the sheet to the impression cylinder 3.
and the blanket cylinder 6 through the printing gap 5. Behind the printing gap 5 the printed sheet 1 is transferred to a further transport drum 7
The transport drum then transfers the printed sheet 1 to the subsequent printing unit.

In order to ensure that the printed sheet 1 is brought into perfect full contact with the circumferential surface of the impression cylinder 3, a blow nozzle 8 is placed on the circumferential surface of the impression cylinder 3 at a predetermined interval before the printing gap 5. The blow nozzle 8 is oriented so that it can be oscillated about the oscillation axis 9 and is connectable to a drive, which drives the blow nozzle 8 in accordance with the working cycle of the printing machine. Make a rocking motion back and forth in the direction of travel. The blowing nozzle 8 is constructed as a sword-type nozzle or as a sword-shaped member consisting of a number of single nozzles or a number of nozzle orifices, so that the nozzle orifice extends over the width of the impression cylinder 3. Over a large part, preferably over the entire width of the impression cylinder. The angular range of the oscillating movement of the blow nozzle 8 is adjustable, and both the setting angle and the turning angle of the blow direction with respect to a perpendicular to the peripheral surface of the impression cylinder 3 passing through the oscillating axis 9 are adjustable. .

If the sword blow nozzle consists of a plurality of single nozzles, it is advantageous for each single nozzle to be individually adjustable. In this embodiment, the blow nozzle 8 is fixed to the tube 11 so as to be adjustable and movable in the circumferential direction of the tube. The tube 11 is supported in a cradle 12 of the printing machine so as to be able to swing about its longitudinal axis. For example, a link transmission 13 is suitable for driving the oscillating movement. The blow nozzle 8 is fitted by means of a tubular casing 17 on the outer circumference of a valve adjustment ring 14, which can be adjusted with respect to the mounting part 15 by means of a screw 16. The valve adjusting ring 14 is laterally guided by driver elements 18 . A radial connecting pipe 19 for an air conduit (not shown) passes through the tubular casing 17 and is fixed in the valve adjustment ring 14 at its inner end. Air control for the blow nozzle 8 is effected by overlapping the radial ports provided in the tube 11 with the inner end of the connecting tube section 19 or the through opening in the casing 17 leading to the blow nozzle 8 . The adjustment, control and operation of the sheet-folding device according to the invention correspond to those described in German Patent Application No. 39 20 730.7. In this embodiment, the blow nozzle 8
As can be seen from FIG. 3, which shows a plan view of the sword-type blow nozzle 8, it has an arrowhead shape with its tip oriented in the opposite direction to the running direction of the printing sheet 1. Instead of this arrowhead shape, it is also possible to use a sword-shaped blow nozzle shaped like an arc, so that the sheet to be printed is first blown out before it enters the printing gap. The sheet is loaded with blowing air from the leading edge of the sheet to the trailing edge of the sheet at the midpoint of the sheet, and the sheet is then simultaneously blown outwardly from the midpoint of the sheet from the leading edge to the trailing edge. Due to the non-contact action of the blow nozzle, the sheet to be printed can be brought into full and reliable contact with the impression cylinder.

[Brief explanation of the drawing]

1 is a side view of a printing unit of a rotary sheet-fed offset printing press; FIG.

FIG. 2 is an enlarged view of the anti-slip nozzle as seen in the direction of sheet travel;

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

[Explanation of symbols]

1 printing sheet, 2 transport drum,
3 impression cylinder, 4 sheet gripper,
5 printing gap, 6 blanket cylinder,
7 Transfer drum, 8 Sword-shaped blow nozzle, 9 Oscillation axis, 11 Pipe,
12 frame, 13 link type transmission device,
14 valve adjustment ring, 15 pedestal part, 1
6 screws, 17 tubular casing,
18 Entrainer, 19 Connecting pipe section

Claims (4)

[Claims] 1. A blow nozzle which is orientable towards the circumference of the impression cylinder and which extends over a large part of the width of the impression cylinder and is for pressing sheets onto the impression cylinder by the force action of flowing air. The blow nozzle is supported so as to be able to oscillate about the oscillation axis, which is parallel to the impression cylinder axis, at a distance from the printing gap, and the blow nozzle is arranged to rotate the printing sheet in accordance with the working cycle of the printing machine. A sheet-fed rotary sheet-fed offset printing machine, which can be connected to a drive device that makes a back-and-forth oscillating motion in the running direction of the press, for smooth contact of printed sheets with the impression cylinder before the printing gap of a rotary sheet-fed offset printing machine. In the paper anti-slip device, both ends of the blow nozzle (8) are offset in the running direction of the sheet (1) with respect to the central area of the blow nozzle, and the blow nozzle Starting from the midpoint, the sheet (1) is prevented from tilting from the leading edge of the sheet toward the trailing edge of the sheet, and at the same time from the midpoint of the sheet toward both outer edges. A sheet-fed sheet tilt prevention device in an impression cylinder of a rotary sheet-fed offset printing machine, characterized in that: 2. Claim 1, wherein the blow nozzle (8) is a sword-shaped nozzle formed in an arc shape.
The sheet-fed sheet anti-slip device described. 3. The sheet according to claim 1, wherein the sword-shaped blow nozzle (8) has an arrowhead shape with a tip oriented in a direction opposite to the running direction of the sheet (1). A device that prevents paper from tilting. 4. The sheet-rolling prevention device according to claim 1, wherein the sword-shaped blowing nozzle (8) consists of a plurality of individual nozzles, each individually adjustable.