IE65402B1

IE65402B1 - Improved printing process and apparatus

Info

Publication number: IE65402B1
Application number: IE267391A
Authority: IE
Inventors: James Kirwan; Cecil Whitty
Original assignee: Smurfit Web Research Limited
Priority date: 1991-07-30
Filing date: 1991-07-30
Publication date: 1995-10-18
Also published as: GB2258191A; GB2258191B; IE912673A1; GB9117553D0; BE1003176A6

Abstract

Paper webs (2, 3, 4, 5) are simultaneously printed on both sides in respective printing units (not shown in Fig. 2). Print on the webs (2, 3, 4, 5) is dried by passing the webs (2, 3, 4, 5) in pairs through drying ovens (12). Downstream of the drying ovens (12) the webs (2, 3, 4, 5) pass over cooling rollers (15) and guide rollers (20) which are adjustable to control the orientation of the webs (2, 3, 4, 5) as they are fed into a folding unit (25). Within the folding unit (25) the webs (2, 3, 4, 5) are cut into sheets and folded. Folded sheets discharged from the folding unit (25) are delivered to a turning device (27) which turns over the folded sheets and drops the folded sheets onto a conveyor (28) such that a folded edge of each folded sheet faces in the direction of travel of the conveyor (28). Descriptions of a damping fluid train, an adjustable web guide and a turning device are given.

Description

This invention relates to a rotary offset printing process and apparatus.

It is known to provide a rotary offset printing process and printing press apparatus in which a number of paper webs are led from storage reels through printing machines, one for each web, which print on the webs. From the printing machines each web is led to a separate drying oven associated with each printing machine to dry the print on the web. Downstream of the drying ovens each web is passed over cooling rollers to cool the web prior to feeding the web into a folding machine which cuts the web into sheets, folds the sheets and discharges the folded sheets onto a conveyer for delivery for further processing such as binding for example.

A number of problems can arise in operating the process. The webs have to be accurately fed through the printing press to ensure efficient continuous running of the press. Any misalignment can ruin a printing min with time lost in correcting the fault and in printing new web material.

Correct feeding of the printed webs into the folding machine is also essential otherwise the web will be incorrectly cut and folded, leading to ejection of the folded sheets, with further down time sent in correcting the fault and printing replacements.

The initial setting up of the printing press is therefore a 5 difficult and time consuming process requiring some considerable skill on the part of the operator.

The present invention is directed towards providing an improved printing process and printing press apparatus which overcomes these problems.

According to the invention, there is provided a rotary offset printing process comprising the steps; (a) leading a pair of webs from rotatable web storage reels to associated printing units, (b) simultaneously printing on both sides of each web at the printing units, each web being passed between a pair of rotating blanket rollers which apply print to the webs. (c) guiding the webs to a drying oven, (d) passing both webs through the drying oven in a single pass together in a controlled manner to dry the print on both sides of each web as the webs pass through the drying oven, the webs being spaced-apart one above the other, carefully controlling the heat input in the oven, the relative spacing of the webs and the speed at which the webs travel through the oven, (e) guiding the webs from the oven to cooling rollers and passing the webs over the cooling rollers, (f) delivering the webs to a folding unit in which the steps of cutting the web into sheets and folding each sheet are carried out, the folded sheets being discharged onto a conveyer which delivers the folded sheets to a further processing station.

In a preferred embodiment of the invention the process includes the step of passing the webs over guide rollers located between the cooling rollers and the folding unit, and adjusting the guide rollers if required to control the orientation of webs fed into the folding unit to correctly feed the webs into the folding unit.

In another embodiment the process includes the step of controlling the orientation of folded sheets discharged from the folding unit such that a folded edge of each sheet is faced in the direction of travel of the folded sheet.

In another aspect, the invention provides a rotary offset printing press apparatus comprising in an in-line arrangement, a pair of rotatable web storage reel supports, a pair of printing units, each printing unit for simultaneously printing on both sides of a web fed from a web storage reel through the printing unit, a drying oven for reception and through passage of both webs simultaneously spaced-apart one above the other, to dry print on both sides of each web as the webs pass through the drying oven, cooling rollers over which the webs are passed to cool the webs, guide rollers over which each web is passed, the guide rollers pivotally adjustable to adjust the orientation of a web passed over the guide rollers for correct feed of the web to a folding machine of the printing press apparatus which cuts the web into sheets, folds the sheets and discharges the folded sheets onto a conveyer.

In a preferred embodiment, the guide rollers for each web comprise a pair of parallel rollers rotatably mounted spacedapart between roller end supports, the roller end supports being mounted on a support frame, one of the roller end supports being pivotally mounted on the support frame, the other free roller end support slidably mounted in a channel on the support frame, a motor driven screw mechanism extending between the support frame and the free roller end support for slidably moving the free roller end support along the channel.

In a further embodiment, a folded sheet turning device is provided below an outlet end of the conveyer, the turning device comprising a rotatable cylinder having a number of spaced-apart outwardly extending spiral arms, adjacent arms defining a slot for reception of a folded sheet.

The invention will be more clearly understood by the following description of an embodiment thereof given by way of example only with reference to the accompanying drawings, in which; Fig 1. is a diagrammatic side view of portion of a printing press according to the invention showing a number of printing units, Fig. 2 is a diagrammatic side elevational view of portion 10 of the printing press, Fig. 3 is a diagrammatic side view of a printing unit forming portion of the printing press, Fig. 4 is a detailed perspective view of portion of the printing unit, Figs. 5 and 6 are detailed views of portions of the printing unit, Fig. 7 is a detailed elevational view of adjustable guide rollers forming portion of the printing press, Fig. 8 is a plan view of the guide rollers, Fig. 9 is a perspective view of a folded sheet turning device forming portion of the printing press, and Fig. 10 is a side view of the turing unit.

Referring to the drawings there is illustrated a rotary offset 5 printing press apparatus, indicated generally by the reference numeral 1 used for carrying out the process according to the invention. The printing press 1 comprises two in-line units for simultaneously printing four webs 2, 3, 4, 5 of paper.

Each web 2, 3, 4, 5 is supplied from a rotatable web storage reel (not shown) and led to an associated printing unit 10. Within each printing unit 10 the webs 2, 3, 4, 5 are simultaneously printed on both sides and upon discharge from the printing units the webs 2, 3, 4, 5 are guided to drying ovens 12. It will be noted that the webs 2, 3, 4, 5 are delivered through the drying ovens 12 in pairs, each pair of webs 2, 3 and 4, 5 passing through one of the ovens 12 together, spaced-apart one above the other to dry the print on the webs 2, 3 and 4, 5. Downstream of the drying ovens each pair of webs 2, 3 and 4, 5 are brought together and led over cooling rollers 15. Downstream of the cooling rollers 15 the webs 2, 3 and 4, 5 are separated and led over guide rollers 20 which are adjustable to control the orientation of the webs 2, 3, 4, 5. Then the webs 2, 3, 4, 5 are fed into a folding unit in which the webs are cut into sheets which are subsequently folded. Folded sheets discharged from the folding unit 25 are delivered to a turning device 27 which turns over the folded sheets and drops the folded sheets onto a conveyer 28 such that each folded sheet faces in the direction of travel on the conveyer 28.

Referring now in particular to Figs. 3 to 6 a printing unit 10 will be described. Each printing unit 10 has a pair of rotatable blanket cylinders 30 between which a web 2 is passed to simultaneously print on both sides of the web 2. Print is applied to each blanket roller 30 by an associated plate cylinder 31 in conventional manner. Damping fluid is applied to the plate cylinder 31 by a number of rollers 32 - 35 extending between a trough 36 forming a fluid reservoir and the plate cylinder 31. The rollers comprise a fountain roller 32 the surface of which extends into the trough 36. A brush roller 33 contacts the fountain roller 32 and transfers fluid picked up by the fountain roller 32 to an intermediate steel roller 34. The roller 34 transfers the fluid via a rubber roller 35 to the place cylinder 31. Means is provided to deliver fluid from a sump 37 to each trough 36. Fluid in each trough 36 is maintained at a preset level such that the fountain roller 32 is always partially immersed.

Referring now in particular to Figs. 7 and 8 the arrangement of the guide rollers 20 will be described. A pair of guide rollers 20 are rotatably mounted between end supports 40, 41.

One end support 41 is pivotally mounted at 42 on a support frame 43. The other free end support 40 is slidably mounted for horizontal movement within a channel 44 mounted on the support frame 43. A motor 46 on the support frame 43 connects through a screw mechanism 47 with the free end support 40. Operation of the motor 46 drives the screw mechanism 47 to slide the free end 40 along the channel 44 thus altering the orientation of the rollers 20 relative to the support frame 43. By adjustment of the guide rollers 20 a web 2 passing over the guide rollers 20 can be adjusted for correct entry into the folding machine 25 ensuring correct positioning of the web 2 within the folding machine 25 for folding. Advantageously, the guide rollers 20 can be adjusted while the printing press 1 is running.

Referring now in particular to Figs. 9 and 10, the turning device 27 will be described. A discharge conveyer 50 discharges folded sheets 51 from the folding machine 25. It will be noted that the folding unit 25 discharges folded sheets 51 with an open edge 52 of the folded sheet 51 facing in the direction of travel of the folded sheets 51. Upon delivery to the turning device 27 the folded sheets 51 are turned over so that a closed edge 53 of each folded sheet 51 is facing in the direction of travel of the folded sheets 51 on the conveyer 28. The turning device 27 has a cylindrical body 55 and is rotatably supported beneath the discharge conveyer 50. A number of spiral arms 56 extend outwardly of a surface of the body 55 curving outwardly of the body 55. A slot 57 for reception of a folded sheet 51 is formed between each adjacent pair of arms 56. As the body 55 is rotated in the direction of arrow A (Fig. 10) folded sheets 51 from the discharge conveyer 50 are dropped into each slot 57 open end 52 first. When the body 55 rotates through approximately 180° the folded sheets 51 drop back out of the slots 57 onto the conveyer 28 in the required orientation.

It will be appreciated that the use of a single oven for a 10 pair of webs has a number of advantages. It was previously believed that it would not be possible to adequately dry a pair of sheets in a single oven and normally a single oven is provided for each web. However, it has been found that by carefully controlling the heat input in each oven, the relative spacing of the webs and the speed the webs travel through the oven, a pair of webs can in fact surprisingly be adequately dried in the oven without adversely affecting the print quality. Thus, advantageously there is large capital cost saving in that only one oven need be provided where previously it was thought that two ovens where required. A further advantage is the improved efficiency and energy saving. Also as less fuel is being burnt to heat the drying air for the oven, pollution due to exhaust gases is also advantageously reduced.

The guide rollers at the entry to the folding machine advantageously ensure correct alignment of a web entering the folding machine. The guide rollers are adjustable when running and thus advantageously accurate positioning of the web can be achieved and the printing press can be quickly and easily set-up and adjusted for optimum running conditions. Advantageously, there is less down time and wastage due to the incorrect feeding of a web into the folding machine.

The provision of the turning device at an outlet of the 10 folding machine advantageously aligns folded sheets with their folded edge facing in the direction of travel. This ensures a smoother delivery of the folded sheets along conveyers for further processing.

The invention is not limited to the embodiment hereinbefore 15 described which may be varied in both construction and detail.

Claims

1. A rotary offset printing process comprising the steps; (a) leading a pair of webs from rotatable web storage reels to associated printing units, (b) simultaneously printing on both sides of each web at the printing units, each web being passed between a pair of rotating blanket rollers which apply print to the web, (c) guiding the webs to a drying oven, (d) passing both webs through the drying oven in a single pass together in a controlled manner to dry the print on both sides of each web as the webs pass through the drying oven, the webs being spaced-apart one above the other, 15 carefully controlling the heat input in the oven, the relative spacing of the webs and the speed at which the webs travel through the oven. (e) guiding the webs from the oven to cooling rollers and passing the webs over the cooling rollers, (f) delivering the webs to a folding unit, in which the steps of cutting the web into sheets and folding each sheet are carried out, the folded sheets being discharged onto a conveyer for delivery to a further processing station.

2. A process as claimed in claim 1 including the step of passing the webs over guide rollers located between the cooling rollers and the folding unit, and adjusting the guide rollers if required to control the orientation of webs fed into the folding unit to correctly feed the webs into the folding unit.

3. A process as claimed in 1 or claim 2 including the step of adjusting the orientation of folded sheets discharged from the folding unit such that a folded edge of each sheet is faced in the direction of travel of the folded sheet.

4. A rotary offset printing press apparatus for carrying out the process as claimed in any preceding claim, comprising in an in-line arrangement, a pair of rotatable web storage reel supports, a pair of printing units, each printing unit for simultaneously printing on both sides of a web fed from a web storage reel through the printing unit, a drying oven for reception and through passage of both webs simultaneously spaced-apart one above the other to dry print on both sides of each web as the webs pass through the drying oven, cooling rollers over which the webs can be passed to cool the webs, guide rollers over which each web is passed, the guide rollers pivotally adjustable to adjust the orientation of a web passed over the guide rollers for correct feed of the web to a folding machine of the printing press apparatus which cuts the web into sheets, folds the sheets and discharges the folded sheets onto a conveyer.

5. An apparatus as claimed in claim 4 wherein, the guide rollers comprise a pair of parallel rollers mounted spaced-apart between roller end supports, the roller end supports being mounted on a support frame, one of the roller end supports being pivotally mounted on the support frame, the other free roller end support slidably mounted in a channel on the support frame, a motor driven screw mechanism extending between the support frame and the free roller end support for slidably moving the free roller end along the channel.

6. An apparatus as claimed in claim 4 or 5 wherein a folded sheet turning device is provided below an outlet end of the conveyer, the turning device comprising a rotatable cylinder having a number of spaced-apart outwardly extending spiral arms, adjacent arms defining a slot for reception of a folded sheet.