Large Scale High Speed Newspaper Offset

Masakazu Akatsuka, Mitsubishi Heavy Industries,ltd., Toshio Yoshikawa, Mitsubishi Heavy Industries,ltd., Satoshi Matsushima, Mitsubishi Heavy Industries,ltd., Koji Nishiyama, Mitsubishi Heavy Industries,ltd., and Shoichi Aoki, Mitsubishi Heavy Industries,ltd.

1. Abstract
We developed newspaper offset press with high productivity, high print quality, and high reliability to meet the expectation from newspaper industry that needs to print high quality newspaper in tight time schedule. (Fig.1)
This press introduced as gDiamond Starh has capability to run at world fastest 90,000 copies for an hour, which enables three sets of Diamond Star presses to complete jobs that needed four sets of conventional speed presses before.
Diamond Star presses also reduced energy consumption by 20% comparing to our old presses.
Variety of fundamental research projects had been done to insure high quality and high productivity simultaneously; structure and vibration analysis, handling of thin paper, stable transfer and supply of ink film in the order of micrometer, to name a few.

2. Technology
Newspaper offset press shown in Fig.2.   (height 15m, length 20m) prints 40 pages of newspaper including 16 full color pages. Main components of the press are reel stands that hold paper rolls, infeed units which control paper tension before printing process, printing units, web path section that arranges page sequence, folder that cuts and folds paper web to produce final newspaper, and control system.

Reel stand and infeed unit
For the stable operation at high speed where 1.2 tons of newsprint roll is consumed in 20 minutes, precise tension control system and automated splicing devices are designed, which reduced paper breaks during print operation.

Printing unit
Color images are reproduced after four separate color printing. Each color must be printed exactly on the same position, otherwise images become blurred. In order to align four color images within some ten micrometer while allowing paper to run at 14m/s, rigid frame and improved roller design for less vibration are applied. Improved ink roller design, based on the research works of emulsified ink transfer at roller nips, also give uniform and vivid print image.

Web path
Paper tension analysis and the simulation technology developed better design method of arrangement of rollers and air floating devices, which enables stable and accurate paper handling at high speed.

Printed paper webs are gathered, cut, and folded at folder where unconstrained paper edges moves irregularly, which tend to cause paper wrinkle and breaks. High speed visualization technology and computer simulation helped us to apply specially designed folding rollers and air jet to reduce paper deformation in the narrow path.

Environmental improvement
Reduction of mechanical losses such as friction, use of fully independently controlled distributed motor drive system and relating technology contributes to energy saving. Stable paper handling and precise ink supply system reduced paper waste from newspaper printing plant that consumes a lot of paper.

3. Conclusion
The first Diamond Star press starts printing from April 2004 ( start production at May 2004). Five sets are in the operation, two are under installation, and five more sets are ordered, which indicate the Diamond Star press is welcomed from the newspaper industry.  (as of September 2004)



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