JP2882922B2 - Ink supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink supply device for an offset printing press.

[0002]

2. Description of the Related Art A conventional ink supply device of an offset printing press will be described with reference to FIGS. 3A and 3B. Reference numeral 1 denotes an ink discharging roller, 5 denotes an ink fountain, 5a denotes an ink fountain main body, and 5b denotes an ink discharging adjusting plate. , 6 is a gap between the ink fountain roller 1 and the ink fountain adjusting plate 5b, 8 is an ink feeding roller, 9 is a group of ink leveling rollers, and is stored between the ink fountain roller 1 and the ink fountain adjusting plate 5b. The ink 4 is guided to the gap 6 between the ink discharging roller 1 and the ink discharging adjusting plate 5b.

[0003] The size of the gap 6 is adjusted by moving the ink discharge adjusting plate 5b in accordance with the amount of ink consumed on paper. If the ink consumption is large, the gap 6 becomes large. The ink 4 moves onto the ink discharging roller 1 through the gap 6, and the thickness of the ink 4 on the ink discharging roller 1 is limited to the size of the gap 6 if the fluid physical property such as the viscosity of the ink 4 is constant. Dominated and proportional to this.

[0004] As described above, the ink 4 transferred onto the ink discharging roller 1 is supplied with a constant proportion of the ink film thickness by the ink feeding roller 8 intermittently contacting the ink discharging roller 1 so as to make the ink kneading level on the downstream side. The toner image is transferred to and supplied to the roller group 9, and then transferred to a plate rubber blanket, and finally to the paper surface. That is, the amount of ink transferred to the paper surface is substantially proportional to the size of the gap 6.

[0005]

FIG. 3 (a) and FIG. 3 (b)
In the conventional ink supply device for offset printing press shown in
If the size of the gap 6 is constant, a constant amount of ink can always be supplied onto the paper surface, but this is based on the premise that the fluidity of the ink 4 passing through the gap 6 is stable.

Generally, printing starts in the morning. Then, as time passes, the surface temperature of each roller gradually increases. At that time, the surface temperature of the ink discharging roller 1 also gradually increases, but is more gradual than the surface temperature of the ink feeding roller 8 or the ink leveling roller group 9. The reason is that the ink feeding roller 8 or the ink mixing roller group 9 rotates at high speed in synchronization with the printing speed, and the temperature rise due to the frictional heat between the roller nips is fast, whereas the ink discharging roller 1 rotates at low speed. In addition, the temperature rises slowly due to intermittent contact with the ink feeding roller 8. As a result, as the ink discharging roller 1 rotates, the temperature of the ink 4 entering the gap 6 gradually increases. An increase in the temperature of the ink 4 lowers the viscosity of the ink.

As described above, the viscosity of the ink 4 entering the gap 6 gradually decreases with the passage of time from the start of printing, and accordingly, the thickness of the ink 4 drawn out from the gap 6 increases. As the amount of ink supplied to the paper surface increases, the density on the paper surface gradually increases. 4 and 5
Indicates the state at this time. In order to keep the printing density constant (to keep the amount of ink supplied to the paper surface constant), it is necessary to narrow the gap 6 as the temperature of the roller increases, resulting in the following disadvantages. (1) The change in the ink supply amount due to the temperature change is long,
Continue slowly. During this time, the print operator cannot stay away from the machine, which places a heavy burden on the print operator. (2) While the ink supply amount is changing as described above,
Even if the size of the gap 6 is the same, the printing density greatly varies, so that it is very difficult to perform color matching at the beginning of printing, and the color matching time is prolonged. As a result, the number of waste sheets generated during color matching is reduced. It has increased.

When printing is started in the morning, the machine is idled to warm the roller surface, but only the ink leveling roller group 9 after the ink feeding roller 8 is heated by the idle rotation. Ink feeding roller 8
Is always in contact with the ink mixing roller group 9 on the downstream side. On the other hand, the ink feeding roller 8 only contacts the ink discharging roller 1 intermittently, and the heat of the ink leveling roller group 9 is
Is difficult to be transmitted to the ink fountain roller 1,
The surface temperature of the ink fountain roller 1 does not rise even by idling.

The present invention has been made in view of the above problems, and its purpose is to reduce the burden on the printing operator. Another object of the present invention is to provide an ink supply device capable of reducing the waste paper generated during color matching.

[0010]

To achieve the above object, the present invention provides an ink supply apparatus having an ink fountain, an ink fountain roller, and a downstream roller subsequent to the ink fountain roller. A heating device that uniformly heats the surface of the ink discharging roller from within the discharging roller, a thermometer that detects the surface temperature of the ink discharging roller and the surface temperature of the downstream roller, and ink discharging from the thermometer. The temperature detection signal of the roller and the temperature detection signal of the downstream roller are compared, and the resulting temperature control signal is sent to the heating device to maintain the surface temperature of the ink discharge roller at the surface temperature of the downstream roller. Temperature control device.

[0011]

The ink supply device of the present invention is constructed as described above, and continuously detects the surface temperature of the ink discharging roller and the surface temperature of the downstream roller after the ink discharging roller by the thermometer. These temperature detection signals are sent to a temperature control device, which compares the temperature detection signal of the ink discharge roller with the temperature detection signal of the downstream roller, and as a result, obtains the obtained temperature control signal. It is sent to a heating device in the ink fountain roller, and the heating device is controlled to maintain the surface temperature of the ink fountain roller at the surface temperature of the downstream roller.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink supply apparatus according to the present invention will be described with reference to an embodiment shown in FIG. 1. Reference numeral 1 denotes an ink supply roller, and 2 denotes a heating device (heat transfer heater for heating) embedded inside the ink supply roller 1. The heating device 2 is provided around the rotation axis of the ink discharging roller 1 along the axial direction, and uniformly heats the surface of the ink discharging roller 1.

5 is an ink fountain, 5a is an ink fountain main body, 5b
Denotes an ink discharge adjusting plate, 6 denotes a gap between the ink discharging roller 1 and the ink discharging adjusting plate 5b, 8 denotes an ink feeding roller, and 9 denotes an ink leveling roller group. Reference numeral 3 denotes a thermometer (for example, an infrared radiation thermometer). To detect continuously. However, when the surface temperature of the ink feeding roller 8 cannot be detected, the surface temperature of any one of the ink leveling rollers 9 is detected. If this is not possible, no detection is performed. In this case, however, it is necessary to grasp the surface temperature of the ink feeding roller 8 during steady operation (see FIG. 2).

7 is the heating device (heat transfer heater for heating) 2
This temperature controller 7 compares the temperature detection signal of the ink discharge roller 1 from the thermometer 3 with the temperature detection signal of the downstream roller (8 or 9). As a result, the obtained temperature control signal is sent to a heating device (heat transfer heater for heating) 2 in the ink fountain roller 1 to lower the surface temperature of the ink fountain roller 1 to the downstream roller (8).
Alternatively, the surface temperature is maintained at 9).

Next, the operation of the ink supply device shown in FIG. 1 will be specifically described. The surface temperature of the ink discharge roller 1 and the surface temperature of the ink feeding roller 8 are continuously detected by the thermometer 3 in a non-contact manner, and these temperature detection signals are sent to the temperature control device 7. Now, the temperature detection signal of the ink supply roller 1 and the ink supply roller 8
And sends the obtained temperature control signal to a heating device (heating heat transfer heater) 2 in the ink fountain roller 1 to turn on / off the energization of the heating device 2. Then, the surface temperature of the ink supply roller 1 is maintained at the surface temperature of the ink supply roller 8.

FIG. 6 shows the result of comparison between the density fluctuation caused by the temperature control and the density fluctuation caused by the conventional gap adjustment. Due to temperature fluctuations over time, the density of the printed matter fluctuates significantly. When the conventional temperature control is not performed (no control), the gap 6 is frequently adjusted by the printing operator.
Since the print operator adjusts the gap 6 only when the solid density of the printed material is outside the allowable range, the dot pattern portion in FIG. On the other hand, when the temperature control of the present invention is performed [with control], the solid density of the printed matter is always within the allowable range, and no waste paper occurs.

[0017]

As described above, the ink supply apparatus of the present invention continuously detects the surface temperature of the ink discharging roller and the surface temperature of the downstream roller after the ink discharging roller by using the thermometer. A temperature detection signal is sent to a temperature control device, which compares the temperature detection signal of the ink fountain roller with the temperature detection signal of the downstream roller, and as a result, outputs the obtained temperature control signal to the ink fountain roller. To the heating device inside the printer, and controls the heating device to maintain the surface temperature of the ink fountain roller at the surface temperature of the downstream roller. The burden can be reduced.

Since the surface temperature of the ink discharge roller is maintained at the surface temperature of the downstream roller by the thermometer, the temperature control device, and the heating device provided in the ink discharge roller as described above, printing starts. Can be easily performed, the color matching time can be shortened, and the waste paper generated during the color matching can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of an ink supply device of the present invention.

FIG. 2 is an explanatory diagram showing a specific example of a temperature control device.

FIG. 3A is a side view showing a conventional ink supply device;
(B) is an enlarged side view showing an ink fountain portion of the ink supply device.

FIG. 4 is an explanatory diagram showing a state in which the solid density of a printed material changes due to a change in the surface temperature of the ink discharge roller at the start of printing.

FIG. 5 is an explanatory diagram showing a state in which the solid density of a printed material changes due to a change in the surface temperature of the ink discharging roller during long-time operation.

FIG. 6 is an explanatory diagram showing density fluctuations when temperature control is performed and when temperature control is not performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink discharge roller 2 Heating device 3 Thermometer 5 Ink fountain 5a Ink fountain main body 5b Ink discharge adjusting plate 7 Temperature control device 8 Ink retrieving roller (downstream roller) 9 Ink leveling roller group (downstream roller)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41F 31/02, 31/26

Claims (1)

(57) [Claims] 1. An ink supply device having an ink fountain, an ink fountain roller, and a downstream roller subsequent to the ink fountain roller. The heating device uniformly heats the surface of the ink fountain roller from within the ink fountain roller. The apparatus, a thermometer for detecting the surface temperature of the ink ejection roller and the surface temperature of the downstream roller, and comparing the temperature detection signal of the ink ejection roller and the temperature detection signal of the downstream roller from the thermometer. A temperature control device for sending a temperature control signal obtained as a result to the heating device to maintain a surface temperature of the ink discharge roller at a surface temperature of the downstream roller. .