JP2005231165A - Offset printing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an offset printing machine wherein printing pressure can be properly adjusted in response to variation in the thickness of a card. <P>SOLUTION: The offset printing machine is equipped with a printing pressure adjusting means for adjusting the printing pressure of an impression cylinder 17 against a blanket cylinder 16 by detecting the variation in the thickness of the card to be printed, and adjusts the printing pressure in response to the variation in the thickness of the card, sheet by sheet. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an offset printing machine.

  In an offset printing machine, cards are supplied one by one from a card supply device on which cards such as paper and plastic are stacked, and sent to the printing machine. The ink image formed on the plate cylinder is transferred to the blanket, and the ink image is transferred to a card fed between the blanket cylinder and the impression cylinder. When printing on a paper card, the variation in the thickness of the paper used for the card is relatively stable with little difference in solids. Therefore, once the printing pressure (pressure applied to the card during printing) is set, printing is in progress. There is no need to adjust the printing pressure.

However, when a resin card such as plastic is used, there is a card group in which the difference in solids is larger than that of paper, and depending on the card manufacturing process, the thickness of each card varies greatly. Due to the variation in the thickness of the card, there is a possibility that the printing position of the ink image is defective or a relatively large printing density difference is generated, and the image quality is deteriorated.
On the other hand, printing is performed by adjusting the printing pressure in accordance with a card having a small thickness in advance, but the print density difference and the variation in printing position cannot be eliminated. Since it was not realistic to adjust the printing pressure once set for each card to be printed, it was not performed.
In addition, when performing printing by connecting a plurality of printing machines when performing color printing, it is necessary to adjust the printing pressure for each printing machine, which is troublesome.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an offset printing machine that can be adjusted to an appropriate printing pressure in accordance with variations in card thickness.

In order to achieve the above object, the present invention comprises the following arrangement.
Detects variation in printed card thickness in an offset printing machine that transfers the ink image formed on the plate cylinder to the blanket and transfers the ink image from the blanket to the card fed between the blanket cylinder and the impression cylinder. Then, a printing pressure adjusting means for adjusting the printing pressure of the pressure cylinder with respect to the blanket cylinder is provided, and the printing pressure is adjusted according to the variation of the card thickness for each card.
Specifically, the printing pressure adjustment means measures the distance to both sides of the card to be printed and detects thickness variation, and the thickness of the reference card thickness according to the detection result of the thickness detection unit. A control unit that calculates a difference ΔT, calculates a variation value ΔP of the printing pressure corresponding to the thickness difference ΔT, adds ΔP to the reference printing pressure value P, and updates the printing pressure value. The printing pressure motor driver is instructed to change to the updated printing pressure value, and the printing pressure is adjusted by rotating the printing pressure motor of the press-fitting / release station mechanism by a predetermined amount.

Another means is that a plurality of printing units for transferring the ink image formed on the plate cylinder to the blanket and transferring the ink image from the blanket to the card fed between the blanket cylinder and the impression cylinder are connected. In the offset printing machine, each printing unit includes a printing pressure adjusting unit that adjusts the printing pressure of the impression cylinder with respect to the blanket cylinder, and when a variation in the thickness of the card conveyed to the first printing unit is detected, the thickness of the card is detected. The printing pressure is adjusted in the printing pressure adjusting means of all the printing units in accordance with the fluctuation of
Specifically, the first printing unit includes a thickness detection unit that detects a thickness variation by measuring the distance to both sides of the printed card, and a reference card thickness according to the detection result of the thickness detection unit. A control unit that calculates a difference ΔT in thickness, calculates a printing pressure fluctuation value ΔP according to the thickness difference ΔT, adds ΔP to the reference printing pressure value P, and updates the printing pressure value, The control unit instructs the first printing pressure motor driver to change to the updated printing pressure value, and rotates the printing pressure motor of the press-fitting / release mechanism by a predetermined amount to adjust the printing pressure. Each of the printing pressure motor drivers is instructed to change to the updated printing pressure value for each card being printed to the second and subsequent control units through the connection control unit.

If the offset printing machine described above is used, a variation in the thickness of the card to be printed is provided by detecting a variation in the thickness of the card to be printed and adjusting the printing pressure of the impression cylinder against the blanket cylinder. Therefore, even if a card having a large variation in thickness, such as a plastic card, is used, printing can be performed with an appropriate printing pressure adjusted for each sheet. Therefore, the printing position accuracy of the ink image is maintained, the printing density difference does not occur, and the image quality is improved.
The printing pressure adjusting means includes a thickness detection unit that detects variations in the card thickness, and a control unit that updates the printing pressure value by adding ΔP to the reference printing pressure value P. The control unit updates the printing pressure. The printing pressure motor driver is instructed to change the pressure value, and the printing pressure motor of the press-fitting / release mechanism is rotated by a predetermined amount to adjust the printing pressure of the impression cylinder against the blanket cylinder, so the printing pressure adjustment is automatic. The work load can be reduced.
In addition, since the printing pressure can be adjusted according to the thickness of each card, lot management by thickness and quality control during printing are not required for each card, improving workability and reducing management costs.
In particular, in an offset printing machine in which a plurality of printing units are connected, when a variation in the thickness of the card conveyed to the first printing unit is detected, the printing pressure adjusting means for all the printing units according to the variation in the card thickness By adjusting the printing pressure at the same time, the printing pressure value of the printing section for each color when full-color printing can be adjusted appropriately at the same time, improving color image quality and workability at the same time. it can.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an offset printing machine according to the invention will be described in detail with reference to the accompanying drawings. The offset printer of this embodiment will be described as an offset printer that performs printing on a resin card such as a plastic card having a thickness of about 0.76 mm.

  First, the schematic configuration of the offset printing machine will be described with reference to FIG. In this embodiment, an offset printing machine having a printing unit for supplying water and ink will be described. The cards K stocked in the card supply unit 1 are separated one by one and fed into the printing unit 2 at a predetermined timing by a card feeding device (not shown). A card thickness measurement sensor 3 (distance sensors A and B), which is a thickness detector, measures the distance to both sides of the card and detects thickness variations.

  The printing unit 2 can perform color printing as well as monochrome printing on the card K. Printing is performed for each color by each printing unit based on image data of a printing plate read for each color by an image scanner (not shown) or image data of a printing plate drawn on a personal computer or the like. The printed card K is discharged to the discharge unit 4. Although not shown, an operation panel is provided in the apparatus main body, and printing start / stop, number of printed sheets, printing speed, ink density, and the like can be arbitrarily set. The printing unit 2 may be an offset printing machine that uses only ink without using water.

Next, a schematic configuration of the printing unit 2 will be described.
The ink fountain 5 stores ink of any one of M (magenta), C (cyan), Y (yellow), and K (black). The ink fountain roller 6 supplies the ink stored in the ink fountain 5 to the ink distributor 7 disposed on the downstream side. The ink distributor 7 adjusts and supplies the ink amount by alternately moving between the ink fountain roller 6 and the ink feed roller 8.

  The ink supplied to the ink feed roller 8 is kneaded by the ink kneading roller group 9 arranged on the downstream side and in pressure contact with each other, and the ink is stretched to prevent a stripe pattern from being generated due to the deviation of the ink. The kneaded ink is supplied to the plate surface of the plate cylinder 11 by the inking roller 10 provided at two places. Further, the water stored in the water tray 12 is pumped up by the pumping roller 13, sent by the water feeding roller 14, and supplied to the plate surface of the plate cylinder 11 by the watering roller 15.

  The plate cylinder 11 is one in which a printing plate is wound around a metal cylinder and the ink image applied to the printing plate is transferred to a blanket cylinder 16. The printing plate is formed, for example, by printing an image printed on the card K by exposing an original image film. The inking roller 10 and the watering roller 15 can be moved toward and away from the plate cylinder 11, and when printing is started, the inking roller 10 and the watering roller 15 are brought into contact with the plate cylinder 11 at a predetermined timing. Ink is supplied to form an ink image.

  The blanket cylinder 16 has a rubber blanket wound around a peripheral surface of a metal printing cylinder. The blanket is stretched by screwing both ends to the opening of the printing cylinder via a jig. An ink image formed on the printing plate is transferred to the blanket cylinder 16 when the plate cylinder 11 is moved toward and away from the blanket cylinder 16. A metal cylinder is used for the impression cylinder 17. The impression cylinder 17 approaches or separates from the blanket cylinder 16 and forms a nip when the impression cylinder 17 approaches the blanket. When the card K passes through the nip, an ink image is transferred from the blanket.

  The blanket cylinder 16 is fixed, and the plate cylinder 11 and the impression cylinder 17 are moved toward and away from each other at a predetermined timing. In the case of this embodiment, when printing is started, the plate cylinder 11 is first pressed against the blanket cylinder 16 (plate pressure enters), and then the impression cylinder 17 approaches the blanket cylinder 16 (printing pressure enters). While the apparatus is in operation, the impression cylinder 17 remains close to the blanket cylinder 16 and the printing cylinder 11 is separated from the blanket cylinder 16 (releases the printing pressure) every time printing is completed. When the operation of the apparatus is stopped, the impression cylinder 17 is separated from the blanket cylinder 16 (releases the printing pressure).

  3A and 3B, an example of a press-fitting / canceling mechanism for applying and releasing printing pressure will be described. A support shaft 25 that supports the impression cylinder 17 so as to be rotatable on both sides in the longitudinal direction is an eccentric shaft, and is provided eccentric to the rotation center of the impression cylinder 17. The support shaft 25 is rotatably supported by the device frame 26. A fan-shaped arm 27 is integrally fitted to the support shaft 25. A sector gear 28 is fixed to the front end side of the sector arm 27. The sector gear 28 meshes with the pinion gear 29. The pinion gear 29 is rotatably supported by the device frame 26. The pinion gear 29 is integrally provided with the rotation shaft 30 of the sector gear 31. The sector gear 31 meshes with a motor gear (not shown) of the printing pressure motor 18. When the printing pressure motor 18 is rotated and the pressure drum 18 approaches the blanket drum 16, printing pressure is applied, and when the pressure drum 17 is separated from the blanket drum 16, the printing pressure can be released.

  When the printing shaft 18 is rotated through the sector gear 31, the pinion gear 29, and the sector gear 28 by rotating the printing pressure motor 18 by a predetermined amount in a predetermined direction with the printing pressure applied, the support shaft 25 is eccentric. The pressure cylinders 17 connected to each other rotate by a certain amount in a predetermined direction, and the gap between the pressure cylinders 17 with respect to the blanket cylinder 16 changes, so that the printing pressure can be finely adjusted. For example, in FIG. 1, the printing pressure is adjusted by moving the position of the impression cylinder 17 close to the position T1 obtained by adding the thickness variation ΔT to the thickness T0 of the reference card K. .

  In FIG. 2, an ink image is formed on the plate cylinder based on image data of a printing plate read by an image scanner (not shown) or image data drawn on a personal computer, and the ink image is transferred from the plate cylinder 11 to the blanket cylinder 16. The ink image is transferred to the card K that is transferred between the blanket cylinder 16 and the impression cylinder 17. The cards K separately supplied one by one from the sheet supply unit 1 are fed into the nip portion in synchronism with the ink image transferred to the bracket by a feeding device (not shown). The card K to which the ink image has been transferred by the printing unit 2 is discharged to the discharge unit 4.

  Next, the configuration of the control system of the offset printing press will be described with reference to the block diagram of FIG. The controller (control unit) 19 is input with a CPU (not shown) that outputs a control command to each part of the apparatus based on a signal input from each part of the apparatus, a ROM (not shown) that stores various operation programs. A RAM (not shown) and the like used as data and a work area for the CPU are provided. A detection signal is input to the control unit 19 from an encoder 20 that detects the amount and position of rotation of the blanket cylinder 16, and a detection signal related to the card position is input from the origin sensor 21, so that the timing of the card feeding operation and the printing operation is achieved. ing. In addition, the distance from the card thickness measurement sensor 3 to both sides of the card K is measured and a detection signal for the card thickness is input to the control unit 19. Further, the control unit 19 outputs a control signal to a main motor 22 that rotationally drives the blanket cylinder 16 and a printing pressure motor driver 23 that drives the printing pressure motor 18 of the press-fitting / release mechanism. When the main motor 22 is driven to rotate, the blanket cylinder 16 rotates, and the plate cylinder 11 and the impression cylinder 17 that mesh with the cylinder 16 rotate (see FIG. 3B).

Here, the printing pressure control operation will be described with reference to the flowchart shown in FIG.
First, the thickness T0 of the reference card K is measured (step S1). Then, a reference printing pressure value P0 is set (step S2). Printing is started by inputting a print start key on an operation panel (not shown) (step S3). When printing is started, cards K are separated and supplied one by one from the card supply unit 1. The card K is sent to the printing unit 2 by the feeding device (step S4).

When the card K passes the card thickness measuring sensor 3, the thickness T1 of the card K is measured (step S5). ΔS1 = S1a−S1b and ΔS2 = S2a−S2b in the schematic diagram of FIG.
S1a: distance between the distance sensor A and the reference card, S2a: distance between the distance sensor B and the reference card, S1b: distance between the distance sensor A and the supplied card, S2b: supplied with the distance sensor B ΔS1: change amount of distance sensor A, ΔS2: change amount of distance sensor B

The control unit 19 calculates a thickness difference ΔT (= T0−T1) from the reference card thickness according to the detection result of the card thickness measurement sensor 3 (step S6).
T0 = S1a-S2a, T1 = T0 + (S1 + S2), ΔT = T0-T1,
T0: Thickness of the reference card, T1: Thickness of the supplied card, ΔT: Difference in thickness between the supplied card and the reference card Next, the control unit 19 sets the printing pressure according to the thickness difference ΔT. A variation value ΔP is calculated (step S7). ΔP = ΔT × k
ΔP: difference between the standard printing pressure value and the printing pressure value for the supplied card, k: conversion coefficient

Next, the control unit 19 adds ΔP to the reference printing pressure value P and updates the printing pressure value. That is, P = P0 + ΔP is updated, and the control unit 19 instructs the printing pressure motor driver 23 to change to the updated printing pressure value, and the printing pressure motor 18 of the press-fitting / releasing mechanism is driven to rotate by a predetermined amount. The pressure is adjusted to P (step S8).
Then, the card K is fed into the printing unit 2, and an ink image is transferred from the blanket when passing between the blanket cylinder 16 and the impression cylinder 17 (step S9). Next, it is determined whether or not to continue card printing (step S10). If printing is to be continued, the process proceeds to step S5. If not, the process proceeds to step S11 to end printing.

  Next, another example of the offset printing machine will be described with reference to FIGS. In the present embodiment, a plurality of printing units 2 that transfer the ink image formed on the plate cylinder 11 to the blanket and transfer the ink image from the blanket to the card K fed between the blanket cylinder 16 and the impression cylinder 17 are provided. The linked offset printing press will be described. Since the configuration of each printing unit 2 is the same, different configurations will be described below.

  In FIG. 6, the offset printing machine is connected to the first printing unit 2 from the card supply unit 1, and the first UV dryer 24 is connected to the downstream side of the printing unit 2. Thereafter, the second printing unit 2 and the second UV dryer 24 are alternately arranged and connected in series (n = 5 in FIG. 5) in series. The card discharge unit 4 is connected to the nth UV dryer 24. Each printing unit 2 is provided with printing pressure adjusting means for adjusting the printing pressure of the pressure cylinder 17 against the blanket cylinder 16. When the variation in the thickness of the card K conveyed to the first printing unit 2 is detected, the printing pressure is adjusted in the printing pressure adjusting means of all the printing units 2 according to the variation in the thickness of the card K.

  Specifically, in FIG. 7, in the first printing unit 2, the control unit 19 measures the distance from the card thickness measurement sensor 3 to both sides of the card separately supplied from the card supply unit 1. A detection signal for detecting variation is input. The card thickness measuring sensor 3 is only the first printing unit 2 and is not provided for the second and subsequent printing units 2. The control unit 19 calculates a thickness difference ΔT between the thickness K1 of the card K and the reference card thickness T0 according to the detection result of the card thickness measurement sensor 3, and calculates a variation value ΔP of the printing pressure according to the thickness difference ΔT. calculate. Then, the control unit 19 updates the printing pressure value P obtained by adding ΔP to the reference printing pressure value P0 and instructs the printing pressure motor driver 23 of the first printing unit 2 to print the printing pressure of the press-fitting / release mechanism. The printing pressure is adjusted by rotating the motor 18 by a predetermined amount. Accordingly, each printing pressure motor driver 23 is instructed to change the printing pressure value P updated for each card being printed to the control unit 19 of the second and subsequent printing units 2 through the connection control unit 24. It has become.

  In each of the above-described embodiments, the offset printing machine for printing on a plastic card has been described. However, the offset printing machine according to the present invention is also suitably used for printing on other cards such as thick paper and resin. .

It is a model explanatory drawing of the principal part of a printing part. It is a model explanatory drawing which shows schematic structure of an offset printing machine. It is explanatory drawing of the press-fit / canceling mechanism which adds or cancels printing pressure. It is a block explanatory view of a printing pressure control system. It is a flowchart which shows printing pressure control operation. It is a schematic explanatory drawing which shows schematic structure of the offset printing machine which concerns on another example. It is a block explanatory view of a printing pressure control system.

Explanation of symbols

K card 1 card supply unit 2 printing unit 3 card thickness measurement sensor 4 card discharge unit 5 ink fountain 6 ink fountain roller 7 ink distributor 8 ink feed roller 9 ink kneading roller group 10 inking roller 11 plate cylinder 12 water tray 13 pumping up Roller 14 Water feed roller 15 Water roller 16 Blanket cylinder 17 Pressure cylinder 18 Printing motor 19 Control unit 20 Encoder 21 Origin sensor 22 Main motor 23 Printing pressure motor driver 24 Connection control unit 25 Support shaft 26 Device frame 27 Fan-shaped arm 28, 31 Fan gear 29 Pinion gear 30 Rotating shaft

Claims (4)

In the offset printing machine that transfers the ink image formed on the plate cylinder to the blanket and transfers the ink image from the blanket to the card fed between the blanket cylinder and the impression cylinder.
It is provided with a printing pressure adjusting means for detecting the variation in the thickness of the printed card and adjusting the printing pressure of the impression cylinder with respect to the blanket cylinder, and adjusting the printing pressure according to the variation of the card thickness for each card. An offset printing machine characterized by.   The printing pressure adjusting means calculates the thickness difference ΔT between the thickness detecting unit that detects the thickness variation by measuring the distance to both sides of the printed card and the reference card thickness according to the detection result of the thickness detecting unit. And a control unit that calculates a printing pressure fluctuation value ΔP according to the thickness difference ΔT and updates the printing pressure value by adding ΔP to the reference printing pressure value P, and the control unit updates the printing pressure. The printing pressure motor driver is commanded to change to a value, the printing pressure motor of the press-fitting / release mechanism is rotationally driven by a predetermined amount, and the gap between the pressure drum and the blanket cylinder is changed to adjust the printing pressure. The offset printing machine according to claim 1. In an offset printing machine in which a plurality of printing units that transfer an ink image formed on a plate cylinder to a blanket and transfer the ink image from the blanket to a card fed between the blanket cylinder and the impression cylinder are connected,
Each printing section includes a printing pressure adjusting means for adjusting the printing pressure of the impression cylinder with respect to the blanket cylinder,
An offset printing machine characterized in that when a variation in the thickness of a card conveyed to the first printing unit is detected, the printing pressure is adjusted in the printing pressure adjusting means of all printing units in accordance with the variation in the card thickness. .   The printing pressure adjustment means provided in the first printing unit measures the distance to both sides of the printed card and detects the thickness variation, and the reference card according to the detection result of the thickness detecting unit A control unit that calculates a thickness difference ΔT from the thickness, calculates a printing pressure fluctuation value ΔP according to the thickness difference ΔT, adds ΔP to the reference printing pressure value P, and updates the printing pressure value. Then, the control unit instructs the first printing pressure motor driver to change to the updated printing pressure value, and drives the printing pressure motor of the press-fitting / releasing mechanism by a predetermined amount to rotate the blanket cylinder of the impression cylinder. Instruct the printing pressure motor driver to change the printing pressure value to the updated printing value for each card being printed to the second and subsequent control units through the connection control unit. The offset printing machine according to claim 3.

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