KBA: Variable Web-Width Capability for 4- and 6-Wide Presses
Press release from the issuing company
February 23, 2004 -- The ability to switch from one web width to another on the fly, without impairing the printing and folding quality, may be a novelty for other manufacturers but has been a standard feature of two-across KBA newspaper presses for some time, and is being specified for an increasing number of our four- and six-across Colora and Commander presses as well.
The flexibility afforded by printing different copy widths on the same press means that a much broader spectrum of products can be handled, boosting plant utilisation and thus profitability. North American printers, especially, have been quick to exploit its potential.
We offer a choice of three options – via the turner bars in the superstructure, a slitter and ribbon mover prior to print, or adjustable formers – to support different production scenarios (frequent or occasional use of different web widths, range of web widths, number of webs). The level of automation (eg inking and dampening preset, draw-roller adjustment and so on) can be determined individually by factoring in production specifications, ease of operation, makeready times, cost-efficiency etc. After evaluating all the relevant parameters we recommend the most suitable option and submit a detailed proposal.
With all three options the individual ribbons are fed over the centre of the former. The modifications needed to the reelstand software, draw rollers at the parallel draw unit, folder, press controls and presetting systems (web tension, ink keys, dampeners with or without shutters), and also in adjacent links in the production chain (reel loading, pre-press and post-press) depend on the spread of web widths specified. Variable trolleys are needed at the infeed unit, horizontally adjustable trolleys (manual, with automated as an option) for the catcher and draw rollers. The photocells monitoring web run are fixed in position within the minimum web width and need not be moved. Storing the setting parameters for the different web widths substantially reduces makeready for repeat jobs.
For production scenarios where changes in web width are the exception rather than the rule, the simplest and most economical option is to guide the web centrally through the printing couples to the turner bars and slit it down the middle in the superstructure. The ribbons are then guided over single or double turner bars to the centre of the formers. Very little conversion work is required. Infeed to the turner bars can be automated.
This option is suitable for all types of printing couples, but only for a maximum of three webs with substantially different widths. It is all the more cost-effective if some of the turner bars used for the main product are surplus to requirements for the titles printed on the off-spec webs and can therefore function as ribbon movers, instead of being disengaged.
With this option, which supports more frequent and rapid changes in web width, the web is pulled in by an automatic webbing-up chain located at the operating or drive side. Immediately prior to entry in the infeed unit it is slit down the middle by two rotating blades which engage like a pair of scissors. The ribbons are then moved into position by turner bars and inserted in the usual way.
Our system is superior to comparable ones on the market because it is easy to retrofit and takes up less space. There is no limit on the number of webs, and the compact slitter/ribbon mover assembly makes for easier conversion and supports extensive automation, which is useful if there is a big difference in web widths. However, it is not suitable for H-type units in wet offset (because of fan-out), nor for heatset production.
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