JP4605747B2 - Printing method in variable printing machine - Google Patents

Description

  The present invention relates to a printing method that enables variable printing in a variable printing machine using a plurality of printing units so that the printing lengths between the printing units do not deviate from each other.

  In a printing machine that performs multi-color printing such as multi-color printing using a plurality of printing units, it is an important requirement to match the print lengths of the patterns in each printing unit. In the case of a general rotary printing machine, for example, as shown in Patent Document 1, the printing pitch is adjusted by finely adjusting the peripheral speed of the impression cylinder and changing the paper feed speed. Things are known.

Japanese Patent Publication No. 4-51456

  However, in the case of a variable printing press having a large diameter part (nip part) and a small diameter part (nip release part) on both the blanket cylinder and the impression cylinder of the printing unit, the nip of the paper during one revolution of the impression cylinder. Therefore, the paper feed speed cannot be changed using the method shown in Patent Document 1 above.

  For this reason, when a deviation occurs in the print length of a printed pattern in a conventional variable printing machine, (1) it is necessary to review the mechanical production accuracy, and adjustment takes time and labor. (2) Since there are various factors that affect the registration accuracy, such as the mounting condition of the plate and blanket, and the mechanical state, it is difficult to pursue the cause when a registration failure occurs unexpectedly due to numerous printing conditions. . (3) Installation of plates, blankets, etc. must be done carefully taking time and effort, and these operations are not easy.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a printing method that solves the above-mentioned conventional problems and can easily adjust the printing length of each printing unit in a variable printing machine individually. Therefore, the method is arranged between a pair of intermittent feeding devices that can feed the paper in the forward running and the reverse running synchronously with the paper running by both the intermittent feeding devices interposed therebetween. A printing cylinder and an impression cylinder, and a small diameter so that there is a gap between the impression cylinder and a large-diameter nip portion that performs printing by contacting the paper between the impression cylinder and the circumference of the printing cylinder. In a printing method in a variable printing machine in which a plurality of sets of printing units each having a nip releasing portion provided in the circumferential direction are arranged, each printing unit is driven by a power source that can be individually controlled to rotate, and serves as a reference. Printing by printing unit When the printing length of the printed pattern by the other printing unit is shifted from the pattern, the peripheral speed at the time of nip with respect to the impression cylinder for each rotation of the printing cylinder of the other printing unit is determined as the other printing unit. Adjust the printing length of the printed pattern to the same speed as the printing length of the reference printing pattern, and restore the peripheral speed when releasing the nip of the other printing unit to the speed before the adjustment. correcting the so that the power source for each revolution combined start of picture printing cylinder of the printing unit in phase with the start of picture printing movement of the printing unit as a reference.

  According to the present invention, in a variable printing machine using a plurality of printing units, when an error occurs in the printing length of a printed pattern by each printing unit, the peripheral speed of each printing unit blanket is rotated at each rotation. It is possible to adjust the printing length to match the printing length without shifting the printing phase. From this, it is possible to easily correct the deviation of the printing length for each printing unit due to the mounting of the plate, blanket, etc., the frequency of remounting the plate, blanket is reduced, and workability can be improved. it can.

  Further, the frequency of mechanical adjustment, accuracy confirmation of parts, etc., and remanufacturing for correcting the printing length is reduced, and adjustment time and assembly time can be shortened. In addition, the occurrence rate of printing length related problems is reduced and maintainability is improved.

  FIG. 1 shows a variable printing machine to which the present invention is to be applied. In the figure, reference numerals 1a, 1b, 1c, 1d denote printing units in which a plurality of sets (for example, 4 sets) are arranged in a printing section on a running line of paper 2. Each of the printing units 1a to 1d is an offset type having the same configuration, and is composed of a plate cylinder 3, a blanket cylinder 4 and an impression cylinder 5 which are in contact with each other and rotate in opposite directions. The roll of the inking device is in rolling contact.

  A blanket 4a having a circumferential length shorter than the entire circumferential length is fixed to the circumferential surface of the blanket cylinder 4 of each printing unit 1a to d, and this blanket 4a is brought into rolling contact with the impression cylinder 5 to form a nip portion. The portion without the blanket 4 a is a nip release portion that does not contact the impression cylinder 5. A printing plate 3 a that is in rolling contact with the blanket 4 a of the blanket cylinder 4 is attached to the peripheral surface of the plate cylinder 3. Each of the printing units 1a to 1d is driven by a single drive motor 6a, 6b, 6c, or 6d such as a sectional motor that can be individually controlled for rotation. The impression cylinder 5 may also be provided with a small diameter portion for the nip release portion.

  The sheet 2 passes between the blanket cylinder 4 and the impression cylinder 5 of each of the printing units 1a to 1d, and is provided on the upstream side and the downstream side of the printing unit, and is intermittently fed by the intermittent feeding devices 7a and 7b that perform normal rotation and reverse rotation. The vehicle travels intermittently at a constant cycle shown in FIG.

  In this variable printing machine, in order to simplify the description, it is assumed that the vertical length of the printed pattern is the same as the peripheral length ab (nip portion) of the blanket 4a. The operation of the sheet 2 in this case is as shown in FIG. In the figure, the vertical axis indicates the traveling speed V of the paper 2 and the horizontal axis indicates time t. Then, one rotation from the start end a of the blanket 4 of the rotating blanket cylinder 4 to the sheet 2 to the contact again is defined as one cycle.

In this cycle, the sheet 2 passes through the nip for a time T ₁ and forward traveling at a speed equal to the circumferential speed V ₁ of the blanket 4a, in this case, rolling contact from the beginning a blanket 4a at the end b distance The image of the top and bottom length ab is printed. The nip releasing unit over time T ₂ of the from the end b of the blanket 4a is separated from the sheet 2 to which the starting end a is rolling contact on the paper 2, is first decelerated simultaneously over time t ₁ when the termination b leaves the blanket 4a from reversed running over a time t _2, then it is accelerated to a peripheral speed V ₁ of the re-blanket 4a. The areas of S ₁ , S ₂ , S ₃ , and S ₄ in each traveling state at this time indicate the respective traveling distances, and S ₃ = S ₂ + S ₄ in the drawing. Accordingly, the travel distance of the sheet 2 at the nip release portion is substantially zero, and the pattern having the length of the nip portion ab is repeatedly printed on the sheet 2. In the figure, T = T ₁ + T ₂ and t ₁ + t ₂ + t ₃ = T ₂ .

  When the vertical length of the pattern is shorter than the circumferential length of the blanket 4a and the blanket 4a has a blank portion, the reverse travel distance in the nip release portion is increased by the blank.

  As described above, the pattern 2 is overprinted at the nip portion ab in each of the printing units 1a to 1d on the sheet 2 that intermittently travels in a constant cycle. The phase in the vertical direction of each pattern at this time is matched by adjusting the installation interval between the printing units 1a to 1d. Further, the fine adjustment in the vertical direction is performed by individually correcting the individual drive motors 6a to 6d in the printing units 1a to 1d.

At this time, in FIG. 3, for example, even if the top ends in the vertical direction of the patterns A and B printed by the two printing units 1a and 1b are matched by the above adjustment, the printing plate error between the two printing units 1a and 1b. For example, the print length may be shifted. Figure 3 shows such a state, slightly shorter print length d ₂ of the pattern B is from d ₁ according to the second printing unit 1b according to the first printing unit 1a to the print length d ₁ of the picture A Suppose that

In this case, the rotation of the single drive motor 6b of the second printing unit 1b to finely corrected, the circumferential speed V ₂ at the nip of the second printing unit 1b (T _1), the first printing unit 1a of the peripheral speed V ₁ of the blanket cylinder 4, as shown in FIG. 2 (b), slow in response to the deviation in length. As a result, the printing lengths of the patterns A and B of the first and second printing units 1a and 1b are the same, and the patterns having different printing plate lengths are printed with the same length. The correction at this time is performed without shifting the starting ends of both the patterns A and B.

Circumferential speed V ₂ of the blanket cylinder 4 of the first second printing unit 1b to the circumferential speed V ₁ of the blanket cylinder 4 of the printing unit 1a of this time, inversely proportional to the ratio of the two print length d _1, d ₂ From d ₁ : d ₂ = V ₂ : V ₁ , V ₂ = d ₁ V ₁ / d ₂ .

  As described above, in the case of printing units having different printing plate lengths, the peripheral speed of the blanket cylinder 4 at the time of nip of another printing unit is set as the printing length based on the peripheral speed of the blanket cylinder 4 of one printing unit. By changing by an amount corresponding to the difference, the print lengths of the patterns of the respective print units are matched.

In one cycle blanket cylinder of the printing unit rotates 1, continuing the peripheral speed of said V ₂ even in the blanket cylinder 4 the nip release unit of the second printing unit 1b for changing the peripheral speed pattern in the next cycle The start position of the top and bottom direction will shift. Therefore, the rotation delay in the nip portion is recovered in the nip release portion for each cycle.

Therefore, for each rotation of the blanket cylinder 4, the rotation of the blanket cylinder 4 in the nip release portion is performed so that the peripheral speed is higher than the peripheral speed V ₁ of the blanket cylinder 4 of the first printing unit 1 a. ₃ , the phase of the starting edge of the pattern on the blanket cylinder 4 of the second printing unit 1b is matched with the phase of the starting edge of the pattern on the blanket cylinder 4 of the first printing unit 1a.

In FIG. 2 (b), P ₁ is shift length of the second printing unit 1b to the first printing unit 1a at the nip portion, P ₂ is the length for recovering the shift length P ₁ in the nip The amount of slip recovery. The _P 3, _{P 4} is the amount of transferred during the transition from _{P 1} to _{P 2,} and the _{P 2} to _{P 1.} And the peripheral speed _{V 3} for recovering the shift length of this time is the speed to be _{P 1 + P 3 + P 4} = P 2 in FIG. 2 (b).

  In the above operation, the printing deviation in the length direction by the plurality of printing units 1a to 1d is detected by the deviation monitoring device or visually detected. The adjustment corresponding to the amount of deviation is corrected by finely adjusting the single drive motor of another printing unit with respect to the reference printing unit. The rotation speed of the single drive motor is corrected by a conventionally known digital correction input or the like.

  In this embodiment, each printing unit has been described as an offset type, but it goes without saying that this may be a printing unit in which the impression cylinder is in direct contact with the plate cylinder.

  In the above-described embodiment, the case has been described in which the print length of the pattern by the other print unit relative to the reference print unit is short. However, the print length of the pattern by the other print unit is longer than the reference print unit. This is the reverse of the above description, and the peripheral speed of the blanket cylinder at the nip part of the other printing unit is made faster than the peripheral speed of the reference blanket cylinder, and the nip release part is slowed by that amount to shift the phase. Recover.

  Further, each of the printing units 1a to 1d is connected to a single drive source via a speed change means that can independently change the rotation speed without using a single drive motor. Also good.

It is a schematic explanatory drawing which shows the variable printing machine to which this invention is applied. (A) is a diagram showing intermittent running of paper, and (b) is a diagram showing a change in rotational peripheral speed in one rotation of the blanket cylinder. It is explanatory drawing which compares and shows the pattern from which the printing length printed by the 1st, 2nd printing unit differs.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a, 1b, 1c, 1d ... Printing unit, 2 ... Paper, 3 ... Plate cylinder, 3a ... Printing plate, 4 ... Blanket cylinder, 4a ... Blanket, 5 ... Impression cylinder, 6a, 6b, 6c, 6d ... Single drive motor 、 A 、 B… Picture.

Claims (1)

A printing cylinder and an impression cylinder which are arranged between a pair of intermittent feeding devices which can perform forward rotation and reverse rotation paper feeding synchronously and sandwich the paper traveling by both the intermittent feeding devices. A large diameter nip portion for printing on the peripheral surface of the printing cylinder between the impression cylinder and a nip release portion with a small diameter so as to have a gap between the impression cylinder. In a printing method in a variable printing machine in which a plurality of sets of printing units provided in the circumferential direction are arranged,
Each printing unit is driven by a power source that can individually control rotation,
When the print length of the print pattern of another print unit is shifted from the print pattern of the reference print unit, the peripheral speed at the nip with respect to the impression cylinder for each rotation of the print cylinder of the other print unit Is adjusted to a speed at which the print length of the print pattern by the other print unit is the same as the print length of the reference print pattern, and the peripheral speed when the nip of the other print unit is released is adjusted. recovered the speed and corrects the so that the power source together with the starting end of the pattern of the printing cylinder of the printing unit as a reference the beginning of the phase of the pattern of the printing cylinder of the other printing units per revolution Printing method in a variable printing machine.

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