JP2799585B2 - Offset printing equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a plate cylinder, a blanket cylinder, and an impression cylinder, and performs printing while transferring a sheet inserted between the blanket cylinder and the impression cylinder. The present invention also relates to an offset printing apparatus having at least the blanket cylinder provided with a depressed portion extending in an axial direction with an appropriate width on a peripheral surface.

2. Description of the Related Art In a conventional offset printing apparatus of this type, an interval between contact positions of a blanket cylinder, a plate cylinder, and an impression cylinder is set to be wider than a width of a depressed portion of the blanket cylinder. Therefore, in the related art, the contact positions of the plate cylinder and the impression cylinder with respect to the depressed portion of the blanket cylinder do not correspond to the non-contact state at the same time.
In at least one contact position, the blanket cylinder contacts the plate cylinder or the impression cylinder.

Problems to be Solved by the Invention For this reason, for example, in the case of skip printing, there are the following disadvantages. That is, in the state immediately before shifting from the printing part to the non-printing part, in other words, in the state immediately before the printing is completed corresponding to the depression of the blanket cylinder and the contact position of the blanket cylinder and the impression cylinder, It is desirable that no new ink be supplied to the blanket cylinder. However, since the blanket cylinder and the plate cylinder are in contact at the contact position, unnecessary ink is supplied from the plate cylinder to the blanket cylinder. Will be done.
At this time, since the blanket cylinder and the impression cylinder are still in a printing state, the blanket cylinder cannot be separated from the impression cylinder. Therefore, conventionally, in order to avoid the supply of insoluble ink to the blanket cylinder, the blanket cylinder is kept in a fixed state, while the plate cylinder and the impression cylinder are configured to be able to approach and separate from each other. Was. However, this configuration has a disadvantage that the device becomes complicated.

Conventionally, the contact positions of the plate cylinder and the impression cylinder both correspond to the depressions of the blanket cylinder, and the cylinders do not come into a non-contact state at the same time. Due to the relative change, printing with different depth widths could not be performed. For this reason, conventionally, in order to correspond to printing with different depth widths, several types of plate cylinders, blanket cylinders, and impression cylinders having different sizes according to the depth of printing are prepared, and these cylinders are appropriately selected. There was a complication that it had to be used.

The present invention has been made in view of such circumstances,
An object of the present invention is to provide an offset printing apparatus capable of supporting printing with different depth widths without replacing a plate cylinder, an impression cylinder, and a blanket cylinder, and eliminating unnecessary ink supply to the blanket cylinder during skip printing. And

Means for Solving the Problems In order to achieve the above object, the present invention comprises a plate cylinder, a blanket cylinder, and an impression cylinder, and performs printing while transferring a sheet inserted between the blanket cylinder and the impression cylinder. On the other hand, at least the blanket cylinder is an offset printing apparatus provided with a depression portion extending in the axial direction with an appropriate width (in the present specification, the width means a length in the circumferential direction) on the peripheral surface, A blanket cylinder is provided so as to be able to contact and separate from the plate cylinder and the impression cylinder by appropriate driving means, and the interval between the contact positions of the blanket cylinder and the plate cylinder and the impression cylinder is such that the blanket cylinder is depressed. The interval is set smaller than the width of the section.

The contact position between the blanket cylinder, the plate cylinder and the impression cylinder is set at a smaller interval than the width of the depressed portion of the blanket cylinder, so in skip printing, the contact position between the blanket cylinder and the impression cylinder is In a state immediately before the end of printing corresponding to the depression of the blanket cylinder, the plate cylinder is in a non-contact state at the contact position of the plate cylinder corresponding to the depression of the blanket cylinder. Therefore, even if the plate cylinder is not separated from the blanket cylinder, no new ink is supplied to the blanket cylinder.

In addition, since the contact positions of the plate cylinder and the impression cylinder can be simultaneously brought into a non-contact state with respect to the depressed portion of the blanket cylinder, the blanket cylinder is moved toward and away from the plate cylinder and the impression cylinder, By relatively changing the phases of the impression cylinder and the blanket cylinder, as shown in FIG. 4, the length of the printing medium to which the printing pressure is applied can be adjusted. Printing with different depth widths.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Here, FIG. 1 is a schematic diagram showing a main part of the offset printing apparatus, FIGS. 2 (a) to 2 (i) are operation explanatory diagrams showing a skip printing operation, and FIG. 3 is a schematic diagram showing a print pattern of skip printing. FIG.

As shown in FIG. 1, ink is supplied to a plate cylinder 1 of an offset printing apparatus from an ink fountain 2 via a plurality of rollers 3a, 3b... 3c, 3d, while a plurality of inks are similarly supplied from a water supply apparatus 4. It is configured to be able to supply water through the rollers 5a, 5b, 5c. The roller 3b is movable toward and away from the roller 3a, and the rollers 3c, 3d and 5c are movable toward and away from the plate cylinder 1. On the other hand, the central angle on the peripheral surface of the impression cylinder 6 is
Depressed portion 7 having a width corresponding to an arc of about 120 degrees, extending in the axial direction, and having a depth of about 1 to 3 mm
Is provided. Then, the plate cylinder 1 and the impression cylinder 6
Are connected to an appropriate rotation drive system (not shown), and are respectively driven to rotate in predetermined directions at the same position.

As also shown in FIG. 1, the blanket cylinder 8 is rotatably supported by an eccentric collar 9 via a bearing (not shown), and a shaft 10 is eccentrically fixed to the eccentric collar 9. The shaft 10 includes:
Outside the frame of the offset printing device not shown,
An arm 11 is attached. A rod 13 of an air cylinder 12, which is a driving means, is pivotally mounted on the upper right end of the arm 11 in FIG. 1. In the state shown in FIG. Is lifted, the blanket cylinder 8 is configured to move to the lower right in FIG. 1 due to the rotational displacement of the shaft 10 and the eccentric collar 9 and to be separated from the plate cylinder 1 and the impression cylinder 6. Contrary to this, when the rod 13 of the air cylinder 12 is protruded and the arm 11 and the right end are pushed down, the blanket cylinder 8 is rotated from the separated state by the rotational displacement of the shaft 10 and the eccentric collar 9. The upper cylinder moves in the upper left direction in FIG. 1 and comes into contact with the plate cylinder 1 and the impression cylinder 6.
It returns to the state shown in the figure. A depression 14 having the same configuration as the impression cylinder 6 is provided on the peripheral surface of the blanket cylinder 8. Further, the blanket cylinder 8 is rotationally driven in synchronization with the plate cylinder 1 and the impression cylinder 6. The plate cylinder 1, the impression cylinder 6, and the blanket cylinder 8
Are the same in size.

The paper 15 (see FIG. 2) is transported by a tractor (not shown) so as to pass between the blanket cylinder 8 and the impression cylinder 7, where printing is performed by applying a printing pressure. And the transfer speed by the tractor is
Only when the printing pressure of the impression cylinder 6 and the blanket cylinder 8 is applied to 15 is controlled by a servo motor (not shown) so as to be synchronized with the rotation speed of each cylinder 6,8. If no printing pressure is applied to the paper 15,
For one rotation of each of the cylinders 6 and 8, for example, by rotating the paper 15 at a speed different from the rotation speed of each of the cylinders 6 and 8, that is, fast, slow, or stopped, or by transporting the paper in the opposite direction. It is configured so that an intermittent transfer operation of transferring a desired depth and stopping at a distance between inches to 14 inches can be performed.

Next, the operation of skip printing the pattern shown in FIG. 3 in the embodiment configured as described above will be described with reference to FIG.

When the blanket cylinder 8 in the state shown in FIG. 2 (i) corresponds to the contact position with the impression cylinder 6, the starting edges of the depressions 7, 14 correspond to:
It is moved in contact with the plate cylinder 1 and the impression cylinder 6 (see FIG. 2 (a)). The paper 15 is transported between the cylinders 6 and 8,
Since it corresponds to each of the depressions 7 and 14, no printing is performed (see FIG. 2 (b)). Then, each of the depressions 7, 14
When the end edges pass through each other, the printing is started (see FIG. 2 (c)), and printing is performed until the starting edges of the depressions 7 and 14 reach the contact positions again (see FIG. 2C). Second
Figures (d) and (e).

At the time of this printing, in the state of FIG. 2 (e) in which the end of the printing is approaching, the contact position between the blanket cylinder 8 and the plate cylinder 1 corresponds to the depression 14, and therefore, regardless of the phase state of the plate cylinder 1. No ink is supplied to the blanket cylinder 8. As shown in FIG. 2 (c), at this point, it is not necessary to supply ink and water for the next printing to the plate cylinder 1, so that the rollers 5c, 3c, 3d are sequentially It is separated from the plate cylinder 1.

When the starting edges of the depression 14 of the blanket cylinder 8 and the depression 7 of the impression cylinder 6 pass through contact positions with each other, printing is completed, and the blanket cylinder 8 is moved away from the impression cylinder 6 (FIG. 2). (F)). Then, in a state where the blanket cylinder 8 is separated from the plate cylinder 1 and the impression cylinder 6, FIG.
As shown in (i), each of the cylinders 1, 6, 8 rotates, and each of the depressions 7, 14 is located at a contact position between the blanket cylinder 8 and the impression cylinder 6.
When the starting edges of the blanket cylinders correspond to each other, the blanket cylinder 8 is again moved into contact with the plate cylinder 1 and the impression cylinder 6, and FIG.
State. Here, when reaching the state shown in FIG. 2 (h), the rollers 5c, 3c and 3d are sequentially brought into contact with the plate cylinder 1 to supply water and ink in preparation for the next printing.

The above operation is repeated to perform the skip printing shown in FIG. 3, but the paper 15 is transported by a length corresponding to the depth of the non-printed portion while the printing pressure is not applied,
In preparation for the next printing.

The present invention is not limited to the above-described embodiment. For example, the depressions 7, 14
However, the depressions 7 and 14 may be provided only in the blanket cylinder 8. Further, the width of each of the depressions 7 and 14 does not need to be the same, and is not limited to a size corresponding to an arc having a central angle of 120 degrees, and can be variously changed according to the depth to be printed. Furthermore, it is not necessary that the sizes of the cylinders 1, 6, 8 are the same. In short, in the present invention, the blanket cylinder 8
What is necessary is just to comprise so that the peripheral length of the contact part with the impression cylinder 6 may become the same. Further, the driving means for moving the blanket cylinder 8 toward and away from the cylinder can be variously changed, for example, a cam mechanism may be used in addition to the air cylinder. Also,
It goes without saying that the pattern of the skip printing performed in the present invention is not limited to the pattern shown in FIG.

Effects As is apparent from the above description, according to the present invention, the interval between the contact positions of the blanket cylinder, the plate cylinder, and the impression cylinder is set to be smaller than the width of the depression of the blanket cylinder, and the blanket By allowing the cylinder to contact and separate from the plate cylinder and the impression cylinder, unnecessary ink is not supplied to the blanket cylinder during skip printing. By changing the phase relatively, the length of the printing pressure applied to the printing material can be adjusted, so that the same printing cylinder, blanket cylinder, and impression cylinder can be used to perform printing with different depth widths. To play.

[Brief description of the drawings]

FIG. 1 shows a preferred embodiment of the present invention, FIG. 1 is a schematic view showing a main part of an offset printing apparatus, FIGS. 2 (a) to (i) are operation explanatory diagrams showing a skip printing operation, and FIG. FIG. 4 is a schematic view showing a printing pattern of skip printing, and FIG. 4 is a schematic view showing a printing state in which a depth width differs due to a change in phase between a blanket cylinder and an impression cylinder. 1 ... plate cylinder, 6 ... impression cylinder, 7 ... depression, 8 ... blanket cylinder, 9 ... eccentric color, 10 ... shaft, 11
…… Arm, 12 …… Air cylinder, 14 …… Depressed part,
15 …… Paper

Claims (1)

(57) [Claims] An image forming apparatus includes a plate cylinder, a blanket cylinder, and an impression cylinder, and performs printing while transporting a sheet inserted between the blanket cylinder and the impression cylinder, while at least the blanket cylinder has a peripheral surface. An offset printing apparatus provided with a depression portion extending in the axial direction with an appropriate width, wherein the blanket cylinder is provided so as to be able to contact and separate from the plate cylinder and the impression cylinder by appropriate driving means, while the blanket cylinder is provided with An offset printing apparatus, wherein an interval between contact positions of the plate cylinder and the impression cylinder is set to be smaller than a width of a depressed portion of the blanket cylinder.