JP2519504B2 - Offset printing machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an offset printing machine.

[Problems to be Solved by the Invention]

In the offset printing process, as shown in FIG. 3, the image 31 at the tip of the plate cylinder is printed as a residual image 31 'on the printing paper.
It may appear on the printed part of the image 32 in the part after the plate cylinder 33.

This phenomenon is a kind of printing error and is called "ghost".

 The present inventors considered the cause as follows.

That is, as shown in FIG. 4, when the ink form roll 42, which is in rotary contact with the plate cylinder 42 for supplying ink, supplies ink to the surface of the image 43 drawn on the front part of the plate cylinder, In addition to the ink form roll that did not supply ink to the tip portion 43 of the plate cylinder, the ink film at the point 44 where the ink was supplied on the ink form roll was adjacent to the point where the ink was supplied. It becomes thinner than the ink film at point 45 (left in Fig. 4).

Therefore, at the next time, the portion 44 to which the ink is supplied and the portion 45 to which the ink is not supplied are the same when the ink is supplied to the surface of the image 46 drawn on the rear portion of the plate cylinder at the same time. The amount of the ink 48 supplied from the part to which the ink has been supplied is smaller than the amount of the ink 47 supplied from the part 45 to which the ink has not been previously supplied (the right diagram of FIG. 4).

Therefore, the amount of ink adhering to the surface of the image drawn on the rear portion of the plate cylinder varies.

Due to this variation, as shown in FIG. 3, a light portion 31 'having a small amount of ink adhered is formed in one image 32 of the printed matter 33 along the contour of the previous image 31.

This light portion 31 'appears as a "ghost" like the afterimage of the previous image 31.

[Conventional technology]

The present inventor tried to solve the problem of "ghost",
We have completed a technology to reciprocate the ink foam roll in the axial direction and wipe off the variation in the thickness of the ink film on the ink foam roll by the distributor roller.
-157549.

[Object of the Invention]

It is an object of the present invention to provide an offset printing machine that can more effectively eliminate "ghosts", and thus perform clear printing without printing errors.

[Structure of Invention]

The present invention does not vibrate left and right the ink form roll 15A that supplies ink to the plate cylinder 12 at the end among the large number of ink form rolls 15A, 15B, 15C, 15D that come into contact with the plate cylinder 12, Other ink form rolls 15B, 15C, 15D ...
Completed based on the finding that not only the ghost but also the difference in shade of ink that occurs between the front part and the rear part of the printing surface is eliminated when one or more of ... It was done.

That is, the offset printing machine according to the present invention, the ink fountain 11
The mixing rolls 13 for transferring the ink from the plate cylinder 12 to the plate cylinder 12, the distributor rolls 14 and the ink form rolls 15 and the rider rolls 16 that freely rotate in contact with their surfaces. The last ink form roll that is equipped and supplies ink to the last plate cylinder 12.
In an offset printing machine prepared so as to reciprocate any one or more of the other ink form rolls 15B, 15C, 15D, ... in the axial direction without reciprocating 15A in the axial direction, ) Lastly, a rider roll 16A that freely rotates by contacting the surface of the last ink form roll 15A that supplies ink to the plate cylinder 12 is provided. (B) The rider roll 16A that contacts the last ink form roll 15A The surface is made of copper, and (c) the rider roll 16A that contacts the last ink foam roll 15A is prepared to reciprocate in the axial direction. .

That is, in order to eliminate the "ghost", all the ink form rolls 15 are reciprocated in the axial direction, whereas in the present invention, a large number of ink form rolls 15A and 15B that contact the plate cylinder 12 are used. , 15C, 15D ........ The plate cylinder is attached to the last part of the plate cylinder 12 in the rotating direction.
To reciprocate any one or more of the other ink foam rolls 15B, 15C, 15D, ... in the axial direction without reciprocating the ink foam roll 15A that supplies ink to the axial direction in the axial direction. The surface of the rider roll 16A that contacts the last ink form roll 15A is made of copper, and the feature is that the rider roll 16A that contacts the last ink form roll 15A is reciprocated in the axial direction. .

The reciprocating motion of these rolls is by an air cylinder or an electromagnet.

FIG. 2 illustrates a roll driven by an air cylinder.

In FIG. 2, the shaft center 21 is fixed to the frame of the offset printing machine and does not rotate and does not move in the shaft center direction O-O '.

Air cylinders 22 are fixed to the left and right of the shaft core 21.

Reference numeral 23 indicates a slider pushed out from the air cylinder.

The slider 23 is slidably attached to the shaft core 21.

A ring 24 is fixed to the center of the shaft core 21, and a slider 25 is slidably mounted.

Reference numeral 26 denotes a coil spring that connects the ring 24 and the slider 25.

 27 shows an air pipe.

The pipe 27 connects a compressor (not shown) and an airtight chamber 28 in the air cylinder via a valve driven by a computer.

 The roll body 29 is made of a cylinder.

The roll body 29 is rotatably supported by the slider 23 via a bearing 30.

Therefore, either the left or right air cylinder's airtight chamber
When air is pressed into 28, the roll body 29 is driven in the axial direction OO ′ by the slider 23 pushed out from the cylinder 22.

Further, when air is discharged from the airtight chamber 28, the roll body 29 is returned to its original position by the slider 25 that is moved by being biased by the coil spring 26.

In this way, the roll body 29 is reciprocally driven in the axial direction O-O 'by the air cylinder 22 and the coil spring 26.

The movement directions of the several rolls driven in this way are preferably opposite to each other.

If the surface of the rider roll 16A that rotates in contact with the last ink form roll 15A is made of copper, it is effective in eliminating the "ghost".

The position where the rider roll 16A is attached is wide in the rear part of the printing machine.

For this reason, the rider roll 16A is not disturbed by other members.
The effect of the present invention can be further enhanced by greatly driving the shaft in the axial direction O-O '.

〔The invention's effect〕

The present invention effectively eliminates "ghosts" of printing errors.

At the same time, there is no difference in the density of ink between the front portion and the rear portion of the printing surface.

This effect is that the last ink form roll 15A that supplies ink to the plate cylinder 12 is fixed without reciprocating in the axial direction, and the surface of the rider roll 16A that contacts the last ink form roll 15A is made of copper. It is remarkably caused by reciprocating the rider roll 16A in the axial direction.

Thus, the present invention is extremely advantageous as it allows efficient printing.

[Brief description of drawings]

FIG. 1 is a sectional side view of an essential part of an offset printing machine, FIG. 2 is a sectional view of an essential part of a roll which is reciprocally driven in an axial direction, a development view of a plate surface of a plate cylinder of FIG. 3, and FIG. FIG. 3 is a cross-sectional side view showing the relationship between the plate surface of FIG. 3 and the ink film on the ink form roll. 11 ... Inkwell, 12 ... Plate cylinder, 13 ... Kneading roll, 14 ... Distributor roll, 15 ... Ink form roll, 16
… Rider roll, 17… Blanket torso, 18… Impressor, 19
... Printing paper, 20 ... Printed matter, 21 ... Axis core, 22 ... Air cylinder, 23 ... Slider, 24 ... Ring, 25 ... Slider,
26 ... Coil spring, 27 ... Pipe, 28 ... Airtight chamber, 29 ... Roll body.

Claims (1)

(57) [Claims] 1. A large number of mixing rolls 13, a large number of distributor rolls 14, a large number of ink form rolls 15 for transferring ink from an ink fountain 11 to a plate cylinder 12, and contacting their surfaces. The other ink form rolls 15B, 15C, 15D, which are provided with a freely rotating rider roll 16 and finally supply ink to the plate cylinder 12, do not reciprocate in the axial direction of the last ink form roll 15A.
In an offset printing machine prepared to reciprocate any one or more of the ... In the axial direction, (a) Finally, contact the surface of the last ink form roll 15A for supplying ink to the plate cylinder 12. It is equipped with a freely rotating rider roll 16A, and (b) the surface of the rider roll 16A that contacts the last ink foam roll 15A is made of copper, and (c) it contacts the last ink foam roll 15A. The offset printing machine is characterized in that it is prepared to reciprocate the rider roll 16A in the axial direction.