Mitsubishi Heavy Industries Technical Review Vol. 60 No. 1 (March 2023)
1Development of "Auto-Pilot Printing (APP)" forNewspaper Web Offset Presses

Mitsubishi Heavy Industries MachineryS ystems, Ltd.
Printing & Packaging Machinery
Headquarters
Printing & Packaging Machinery Sales
Department

Mitsubishi Heavy Industries Machinery Systems, Ltd. (MHI-MS) developed the automatic
operation function, "Auto-Pilot Printing," for newspaper web offset presses (hereinafter, "offsetpresses") jointly with The Yomiuri Shimbun. The verification of this function was conducted withthe actual equipment at the Tsurumi Plant of The Yomiuri Shimbun, and the function is already inoperation. Conventionally, the operations for paper tension control and various settings required at
the start-up of an offset press relied on the operators' experience and skills. With the Auto-Pilot
Printing function, these operations are automatically conducted using AI, and the operations fromthe initial setting before the start-up of an offset press to the stop of the offset press are also
automatically conducted. Therefore, in case of emergency situations such as the occurrence ofdisasters or the expansion of infectious diseases, even a limited number of operators cantemporarily operate the offset press. The Yomiuri Shimbun, with which MHI-MS jointly developed
this function, received the "2022 Newspaper Technology Award" for this function from Nihon
Shimbun Kyokai (The Japan Newspaper Publishers & Editors Association).

|1. Introduction
Although automatization of offset presses has been advanced, manual operations are stillrequired at the start-up of an offset press and in the final check of pages of newspapers. It is not too
much to say that whether an offset press is started up in a short time and high-quality newspapers
can be printed depends on the operator's experience and skill. Due to retirement of skilled
operators, however, a shortage of operators and acquirement and handing down of the operating
technique are becoming major issues. Furthermore, even if the number of operators temporarily
decreases in emergencies like the recent coronavirus pandemic or the occurrence of disasters,newspapers need to be printed as usual. In order to solve these problems, we developed theautomatic operation function using AI, "Auto-Pilot Printing (hereinafter, APP)." At present, theAPP requires the manpower to respond to problems and labor saving in the operation of theequipment; this is yet to be achieved. But, at a plant operating multiple sets, a future reduction of
the total workforce can be expected with this technology. This report describes the development
policy, system overview, key technologies and future development of the APP.

|2. Development policy
We worked on the development of the function under the development policy of printing
newspapers having a good printing quality close to the quality controlled by skilled operators,
without manual operation. In the conventional operation by operators, the operators controlled theweb tension at the startup of the offset press, increased the print inspection speed (generally, 60,000copies/hour (paper speed of 4.6 m/s)) and repeated the operations such as registering, color tone
control and paper cutting position adjustment to judge the printing quality. After good printing
quality was obtained, the operators increased the paper speed to the operating speed (generally,120,000 to 130,000 copies/hour (paper speed of 9.1 to 9.9 m/s)), and after the operating speed wasreached, the operators conducted only fine adjustments, and no major adjusting operations wererequired. Therefore, in order to eliminate the operations by operators after the start-up of an offset

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press until the operating speed is reached, we focused our efforts on increasing the precision ofvarious initial setting values ([1] AI preset function), [2] enhancing the web tension control at thestartup of an offset press, and [3] developing an automatic good printing quality judgment function.
With these technologies, as shown in Figure 1, we could automatize the operations that wereconventionally conducted manually or semi-automatically as well as all the operations that wereconventionally conducted by operators, "start-up operation," "preparatory printing operation,""good printing quality judgment," "increase in speed to the operating speed" and "operatingcontrol."Figure 1

Overview of APP|3. System overview
Figure 2 shows the general configuration of an offset press. An offset press mainly consistsof a paper feeding section, a printing section, a web path section and a folding section. Printing isperformed at the printing section while web attached to the paper feeding section is unrolled andthe web is passed through the web path section, cut into a newspaper format and folded at thefolding section. When a number of printing sections are connected, newspapers having a number ofpages can be produced. In addition, when the paper passing route of the web path section ischanged, the position of a color page can be changed. Figure 3 shows the configuration of thecontrol system of an offset press. It generally consists of an offset press control system, CCS-PC(Computerized Control System by Personal Computer) (Note 1), which monitors the condition of thewhole offset press and conducts (presets) various initial settings and a PLC (Programmable LogicController) control system which controls the whole offset press. The key technologies described inchapter 2 which are the basis of the APP are realized as follows: (1) the AI preset function isrealized by collection, learning and management of various offset press data by the CCS-PC, and(2) the tension control at the startup of an offset press and (3) the automatic good printing quality
judgment are realized by the PLC control system. These three key technologies are describedbelow.
Note 1: In a special specification, the function of the CCS-PC may be incorporated in the PLC and PC may
be eliminated. In this case, a dedicated PC for the AI preset function (PC for operation support) isprepared and connected to the PLC control system.

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Figure 2

Newspaper offset press

Figure 3 Overview of the control system|4. Key technologies of APP
4.1AI preset function

Conventionally, values adjusted by the operators were incorporated for the initial setting at
the time of the next printing preparation and for generation of a speed function (Note 2). In an offset
press using consumable items having different usage states and different materials, the adjusted
values in the previous operation may not be appropriate to the next operation. Therefore,
adjustment was conducted on an as-needed basis, relying on the operators' experience and skill. In
this development, we statistically analyzed the accumulated data (one-way analysis of variance)
and found the tendency that the data can be classified by a manufacturer of web paper, kind ofpaper, web width and printing pattern. We constructed a dedicated AI engine for machine learningof each classified data and incorporated it in the CCS-PC. To this dedicated AI engine, theimprovements described below were made, so that high-precision initial setting values and speedfunction for each classified data can be generated, resulting in the elimination of the operations not
only at the time of start-up and during an increase in speed but also during a decrease in speed.
(1) In consideration of the deterioration status of a consumable item that may affect theinitial setting target, learning is conducted according to the number of days for which theconsumable item is used.
(2) Abnormal data (such as a sample value substantially deviated from the original learnedvalue) is not incorporated.
(3) In learning speed function, by putting restrictions not to incorporate sample values
substantially different from the original function, the precision of the speed function isalso increased.
Figure 4 shows one example of the learned data of the initial setting values for registering in
the vertical direction of the page. As shown, the initial setting values gradually changed according
to the number of days for which the consumable item was used, and when the consumable item wasMitsubishi Heavy Industries Technical Review Vol. 60 No. 1 (March 2023)
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replaced, the values returned to the initial setting values. Thus, with consideration given to thenumber of days for which a consumable item was used, the precision of the initial setting values
could be substantially improved.
Note 2: Various setting values need to be adjusted according to the operating speed of an offset press. Theadjustment amount for each operating speed is preset as a function and when the preset operating speed
is reached, the registering position is moved by the adjustment amount to the operating speed. This is apredictive control function.

Figure 44.2

Learned data for AI preset values

Enhanced tension control at the start-up of an offset press

Conventionally, the operator monitored the web tension on a monitor, predicted the state oftensioned web and increased the operating speed at the operator's discretion. With the APP, thetension control is started at the start-up of the offset press. The tension of the web is controlled at acertain level or above, sequentially from the most upstream paper feeding section to the inlet of themost downstream folding section. However, with some web passing routes, even after the infeed
tension was controlled, the tension at the web gathering section (before the web was inserted in thefolding section) did not exceed the threshold and the speed could not be automatically increased. Insuch a case, when the compensator (cutting position adjustment roller) on the route concerned istemporarily moved to the web tension direction, the tension at the web gathering section (before theweb is inserted in the folding section) exceeds the threshold and the speed can be automaticallyincreased.

4.3

Automatic good printing quality judgment

Conventionally, the operator judged the printing quality by visual inspection. With the APP,
whether the printing quality is good is judged based on the correction signals from the automatic
control devices for paper cutting, registering and color tone. Specifically, each sensor for theautomatic control devices for registering and color tone is installed at the exit of the printing unit,
and a sensor for the automatic control device for paper cutting is installed at the web gathering
section (before the web was inserted in the folding section). When the above-mentioned correction
signals from the automatic control devices are not received and the printed page, which has goodquality in the above-mentioned positions of the sensors, is ejected to the exit of the folding device,
the page is judged as having good printing quality in the whole system. In the future, we will make
improvements so that the printing quality is judged not based on correction signals but based ongood printing quality signals received from the automatic control devices and the good printing
quality judgment can be conducted with higher precision according to the printing pattern.

|5. Future prospect
MHI-MS is currently working on the development of the following automatic speed control
function toward further automatization and labor saving:<Automatic speed control function>
In printing of newspapers, the necessary number of copies and the printing finish time
are predetermined and the necessary number of copies must be printed at an appropriate
operating speed by the printing finish time. However, if any problem occurs during theMitsubishi Heavy Industries Technical Review Vol. 60 No. 1 (March 2023)
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printing operation, such as massive paper ejection due to defective pages detected andstopping of the operation due to web breaks, the printing with the last operating speed
setting may not be completed by the printing finish time, and therefore, the operator
adjusts the operating speed. This function will automatically adjust the operating speed
so that the printing can be completed by the printing finish time in the event of aproblem. In a plant having multiple sets, it will allow the operating speed to be
automatically adjusted in view of the state of problems in other sets as well.
Moving forward, we will complete the above function and also continuously make
improvements based on requests from our customers. The APP can be added not only to new offset
presses but also to existing offset presses without renewal of the offset presses and respond to theneeds of existing plants having fewer and fewer skilled operators. We will continue to contribute tothe stable operation of offset presses with the APP for a wide range of customers.