JP2007090887A - Alignment method of printed pictures of sheet-fed offset rotary press - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To guarantee the positioning alignment of the printed pictures of the sheet-fed offset rotary press to have its first print meeting the registration and at the same time to have printed pictures positioned exactly to the sheet paper edges. <P>SOLUTION: The invented method is employed to detect the printing plate position P1 of all the printing plates P, decides the aggregated aligned position between the printing plates and paper sheet positions considering, in the main or control computer positioning optimization process, the adjustment allowances of the registration adjustment device and the sheet paper positioning means VM, SM, to calculate the setting values for the registration adjustment device and the adjustment device of the sheet paper positioning means, and to send the setting values into the registration adjustment device and the adjustment device of the sheet paper positioning means to correct the printing plate position P1 and the paper sheet position B1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printing image alignment method for an offset sheet-fed rotary printing press based on the superordinate concept of the first claim.

In offset sheet-fed printing, the position of the printing plate on the plate cylinder for accurate overprinting of multiple partially printed images, or when creating images on a printing press (Direct Imaging), adjusting the position of the plate cylinder It is well known. For this purpose, a registration adjusting device capable of moving the printing plate at least in the circumferential direction or in the lateral direction is used. In some cases, the diagonal registration can be corrected to correct the tilt of the printing plate.
Furthermore, in modern sheet-fed printing presses, it is possible to adjust the position of the sheet when transported through the printing press. For this purpose, a motorized adjustment device for the sheet alignment of the sheet feeding device and a diagonal registration adjustment device for the transfer cylinder are used. If the transferred partial print image is tilted with respect to the edge of the sheet as a result of incorrect image creation or incorrect mounting on the plate cylinder, the sheet is removed by the diagonal registration adjustment device on the transfer cylinder. Can be tilted in front of each printing area. The front and side mark adjustment devices can adjust the sheet position in the vertical and horizontal directions and can be tilted with respect to the standard position before the sheet is conveyed to the first printing device.
To determine the misalignment between the partially printed images, the print position is determined by performing a trial print in the preparatory operation of the printing press and adjusting the register and mark adjustment device until an accurate overprint is obtained. It is normal to correct the deviation.
In that case, waste paper is generated and time consumption is disadvantageous. It is well known to reset the register adjuster to zero when changing orders, or to set a predetermined value that corrects systematic errors in the preceding process.
In order to correct the stochastic position error that appears in the process from the preparation of the printing plate to the completion of the exchange of the printing plate, it is possible to detect the position of the printing plate on the plate cylinder with a scanning system connected to a computer, DE 3136703 C1. Is known by. The scanning system detects the register mark coordinates on the printing plate and, if different from the target position, activates the registration adjustment device until all the printing plates are positioned at a common target position.

The disadvantage of this solution is that the position of the partially printed image relative to the edge of the sheet is not taken into account. Further, when the adjustment distance is exceeded and the deviation is often large in the same direction, complete correction is impossible because the adjustment distance of the register adjusting device is as small as about ± 1 mm according to the correction principle described above.
German Patent DE 3136703C1

  Therefore, the basis of the present invention is to propose a printing image alignment method that guarantees that the initial printing is already performed in register and the printed image is aligned with the edge of the sheet. It is a problem.

This problem is solved according to the invention by the features of the first claim.
Before starting the printing operation, according to the present invention, first, all the printing plate positions and the sheet positions designated by the sheet aligning means are detected, and the register adjusting device is used in the position optimization process of the main or control computer. The printing plate and the sheet target position that are aligned with each other in consideration of the adjustment range of the sheet alignment means adjustment device, and the settings for the register adjustment device and the sheet alignment means adjustment device The value is calculated and sent to the register adjusting device and the sheet aligning means adjusting device for correcting the printing plate position and the sheet position.

  In particular, the present invention incorporates sheet alignment means into the automated print image alignment so that the printed image is already accurately aligned with the edge of the sheet in the first run, and the position of the printing plate and sheet is Combining corrections has the advantage that the available correction range can be expanded compared to the limited adjustment range of the register adjustment device.

  The method of the present invention will be described in detail with an example of an offset sheet-fed rotary printing press using a printing plate on which an image is created externally.

The sheet B to be printed is sent to the first offset printing apparatus by the paper feeder. In this case, the sheet B is fed from the pile, separated one by one, and sent along the sheet feed line as a flow of overlapping sheets, and the sheet alignment means VM and SM perform sheet feeding. Aligned according to the front and side edges, then gripped by the front gripper, accelerated, and transported to the first printing device.
In this case, the sheet is aligned with the front and side marks VM and SM, as is well known. First, the front side of the sheet B is fed along the paper feed line to the front (front mark VM). This can be done by pulling sideways to the horizontal mark SM, so that all sheets B are in the same alignment position before being pulled into the first printing device.
For the realization of the method according to the invention, front and side marks VM, SM, which can be electrically adjusted on the plane of the paper table, are provided on the paper table, and their positions can be detected by known position measuring devices. .
In the sheet alignment without the marked line, the gripper system that holds the sheet B is moved in the axial direction to the sheet alignment position B1 while the sheet is being conveyed, so that the sheet feeding table and the first sheet are aligned. The lateral alignment of the sheets is performed during conveyance by a paper feed cylinder disposed between the printing apparatuses.
As with the horizontal mark adjusting device, the holding rod of the paper feed cylinder is equipped with a position measuring device and an electric adjusting device.
In the printing apparatus, the sheet B is passed over the impression cylinder, and a partial print image of a certain color is imprinted at that time, and then the sheet B is conveyed to the subsequent printing apparatus by the delivery cylinder.
A partially printed image is produced by inking a printing plate stretched over a plate cylinder and having an inking area and an ink exclusion area.
The rubber cylinder rolls in contact with the surface of the plate cylinder.
The rubber cylinder receives the partially printed image from the inking area of the printing plate, contacts the impression cylinder and transfers to the sheet that is passed over it.
The printing plate P is fastened to a clamping device.
As is well known, the clamping device can be moved circumferentially or laterally separately by electric force or together with the entire plate cylinder by a peripheral and lateral register adjusting device (not shown).
For the detection of the plate position P1 on the plate cylinder, a well-known position measuring device K, in particular an optical sensor such as a video camera or a scanner, is provided to locate register marks on the printing plate P or other important features of the printed image. Alternatively, the position of a reference element of the printing plate P, such as a depression or a punch hole, with respect to the plate cylinder is detected, and its coordinates with respect to a predetermined zero point are determined.
A clear arrangement of the register marks on the printing plate P necessary for this is performed at the time of image creation.
The plate cylinder position measuring device (K) and adjusting device, and the paper feed marks VM and SM are connected to the main and control computers of the network of the printing press.
The computer calculates the misregistration from the zero point of the printing plate P, compares it with the current position of the sheet alignment means VM, SM for specifying the sheet position B1, aligns them with each other, and determines the optimum from there A register and a paper feed mark / preset signal that are synchronized with each other are determined in accordance with the computer program, and are output to the adjusting device.

Before the start of printing, the position measuring device K detects the shift of the register mark position in the first stage, thereby detecting all the printing plate positions P1 with respect to the zero point. Determine lateral and diagonal registration errors.
The next step is to first determine an optimal printing plate target position P2 that can be set within the range of adjustment distances that all registration adjustment devices are capable of, and then the printed image is aligned parallel to the edges of the sheet, The sheet target position B2 is adjusted to the target position P2 of the printing plate P by adjusting the front and horizontal marks until printing on the paper surface at a predetermined position in the horizontal direction.
In the determination of the registration correction value so far, after determining the plate position and the difference between the plate position and the zero point, the “base ink” (reference printing apparatus having the average register mark position) is determined, and the other printing plate P is determined accordingly. It was normal to line up.
The solution according to the invention eliminates this manual operation and automatically optimizes not only the printing plate alignment but also the sheet alignment according to the minimum adjustment distance and available adjustment range criteria. Set values for correction of the printing plate and sheet position are controlled or optimized by the main computer, all partially printed images are overprinted in perfect match, and the printed images are in place. It is imprinted in the vertical, horizontal and diagonal directions with respect to the edge of the sheet.
For example, if complete correction of the registration error in the same direction of the printing plate P is impossible within the available registration adjustment range (within 1 mm), conventionally, the printing plate P with extremely large misalignment must be re-strung on the cylinder. did not become. This operation required a large amount of time.
By introducing a large adjustment range (up to 10 mm) of the sheet alignment means VM, SM according to the invention, this time consumption can be avoided.
For example, if it is not possible to completely correct the inclination of the print image by the plate cylinder registration adjusting device, or if there is no diagonal registration adjusting device in the plate cylinder, the paper feed mark VM, SM or the diagonal of the delivery cylinder before starting printing. By automatically tilting the registration, the sheet B can be preset diagonally at the same angle so that the parallelism between the printed image and the sheet B does not need to be reworked later by a cumbersome manual operation. .
The advantages of the solution according to the invention are also evident for all printing plates P in the same direction of surrounding or lateral misregistration beyond the adjustment range of the registration adjusting device. By automatically automatically correcting the paper feed mark position of the paper feeding device by the average value of the deviation as appropriate, this positional error that occurred during plate exposure, possibly due to inaccurate print image positioning, can be easily corrected.

FIG. 2 shows a schematic diagram of alignment of a printing plate and a sheet.

Explanation of symbols

B Sheet B 1 Sheet position before alignment B 2 Sheet position after alignment P Printing plate P 1 Printing plate position before alignment P 2 Printing plate position after alignment SM Horizontal mark VM Before Mark K Position measuring device, optical sensor, video camera

Claims (5)

At least one printing device having a plate cylinder carrying the printing plate (P);
A sheet feeder (B1, B2) having sheet alignment means (VM, SM) for realizing the matched sheet position (B1, B2);
A position measuring device for the sheet alignment means (VM, SM) and an adjustment device for correcting the sheet position (B1) designated by the sheet alignment means (VM, SM);
A position measuring device (K) for determining the printing plate position (P1, P2) on the plate cylinder and a register adjusting device for correcting the printing plate position (P1);
A main or control computer for controlling the register adjusting device and the adjusting device of the sheet alignment means (VM, SM), connected to the position measuring and adjusting device;
In the method of aligning the printed image of the offset sheet-fed rotary printing press equipped with
Before printing
Detect the printing plate positions (P1) of all printing plates (P),
In consideration of the adjustment range of the registration adjustment device and the adjustment device of the sheet iron making means (VM, SM) in the position optimization process of the main or control computer, the printing plate and the sheet position (P2, B2)
A setting value for the register adjusting device and the sheet aligning means (VM, SM) is calculated, and a register adjusting device for correcting the printing plate position (P1) and the sheet position (B1) Sending to the adjusting device of the sheet alignment means (VM, SM). Considering the minimum adjustment distance in the position optimization process,
Determining the printing plate position (P2) that produces the overprint of the partially printed image that matches the registration,
The partially printed image is aligned with the printing plate target position (P2) so that the edge of the partial print image is aligned in parallel on the sheet (B) aligned with the sheet target position (B2). 2. The method according to claim 1, wherein the sheet target position (B2) is determined.   2. A method according to claim 1, characterized by a diagonal registration adjustment device as a means for aligning the front or side mark (VM, SM) and / or the sheet of the delivery cylinder of the feeding device.   The method according to claim 1, characterized in that each plate cylinder has an electrically adjustable perimeter, side and diagonal registration adjustment device.   As a position measuring device (K) for detecting the printing plate position, an optical sensor, in particular a video camera, a register mark on each plate cylinder for determining the register mark position or a printing plate scanner (registered with respect to the printing plate (P)) 2. The method according to claim 1, wherein the mark position is fixed).

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