EP1386873A1

EP1386873A1 - Method for automatically generating data for setting up a folding machine

Info

Publication number: EP1386873A1
Application number: EP02102093A
Authority: EP
Inventors: Jozef Dechamps
Original assignee: Agfa Gevaert NV; Agfa Gevaert AG
Current assignee: Agfa Gevaert NV; Agfa Gevaert AG
Priority date: 2002-08-02
Filing date: 2002-08-02
Publication date: 2004-02-04
Also published as: JP2004067391A

Abstract

A method for automatically generating data for setting up a folding machine (20) for folding a product, the method including (a) generating first data indicating a folding order and (b) generating second data indicating a dimension of said product.

Description

FIELD OF THE INVENTION

The invention relates to the field of the post-press process of folding, by means of a folding machine, and in particular to setting up a folding machine.

BACKGROUND OF THE INVENTION

To manufacture a product such as a book or a leaflet, several steps are performed: printing, folding, and possibly cutting and binding. Usually, several pages are printed on the same sheet. After folding, these pages of course have to follow one another in the correct order in the final product; this is a job of the imposition process. The imposition process is part of a pre-press workflow system.
As discussed in patent US-A-6 046 818, imposition is the pre-press process of arranging the pages, that will be printed on the same sheet, in such a way that a proper sequence or position of each page relative to the other pages on the sheet is achieved. An imposition plan represents the layout according to which the individual pages are arranged on a sheet, possibly including the relevant dimensions, i.e. the dimensions of the sheet, the dimensions of the individual pages and the dimensions of the spaces at the borders and between the individual pages on the sheet.
As opposed to imposition, which is a pre-press process, folding is a post-press process. Folding is customarily done by means of a folding machine, as disclosed e.g. in US-A-6 251 055. The instructions that the operator of such a folding machine gets, are often very poor. In the worst case, the operator gets no instructions at all, only the imposition plan, and has to deduce from the imposition plan how the sheet has to be folded. The operator then observes the imposition plan and uses his professional knowledge of how such an imposition plan, or a similar one, is commonly folded. He then verifies his assumptions by folding one sheet manually and verifying the obtained order of the pages. If the folded result is correct, he sets up the folding machine accordingly. In a better case, the sheets to be folded are accompanied by instructions for setting up the folding machine. However, the setup operation is not always obvious, since the same folding result may sometimes be obtained by completely different settings of the folding machine. In such a case, the operator usually prefers the settings that are easiest for him, but these are not necessarily the optimal settings.
There is thus a need for an improved method for setting up a folding machine.

SUMMARY OF THE INVENTION

The present invention is a method for automatically generating data for setting up a folding machine as claimed in independent claim 1. Preferred embodiments of the invention are set out in the dependent claims. Preferably, a method in accordance with the invention is implemented by a computer program as claimed in claim 10.
In a method in accordance with the invention, data are generated automatically for setting up a folding machine. Preferably, the data include first data indicating a folding order and second data indicating a dimension of the product that is to be folded.
In this document, a "product" means a book, a leaflet, or any other object that requires a printing step and a folding step in order to be manufactured. E.g. a section (also called signature) of a book is also a product.
The product is printed on one or more "sheets". In this document, a "sheet" is also referred to as a "printing substrate". The printing substrate may be made of paper, cardboard, plastic, sticker material, etc. The term "sheet" encompasses a cut sheet as used for sheet-fed printing presses and a continuous printing substrate on roll as used for web printing presses.
A sheet is also a product.
It is preferred that at least the first data, that indicate the folding order, have a machine-independent format. These first data may be represented as what is called a "folding formula" in this document. A "folding formula" is a description that simply indicates the result that is to be achieved, e.g. "fold one third of the sheet upwards"; it does not indicate how a particular folding machine will attain this result. A folding formula is thus machine-independent. A folding formula uniquely describes how a sheet has to be folded. From a folding formula, the corresponding imposition plan can be deduced by means of a simple algorithm, as will be discussed further below. A folding formula can be used for the automatic setup of a folding machine (provided the folding machine offers the possibility of automatic setup, i.e. its settings can be adjusted automatically, e.g. by a computer program running on a computer coupled to the folding machine).
In a preferred embodiment of the invention, at least the first data, that indicate the folding order, and that are used to set up the folding machine, are based on the optimal imposition plan for the product that is to be manufactured. Our patent application EP 02 102 092.0 entitled "Method for automatically determining an imposition plan", and filed on the same day as the present application, discloses how the optimal imposition plan is calculated.
An advantage of a method in accordance with the invention is that all possibilities of the folding machine may be used.
Another advantage is that the data for setting up the folding machine are generated automatically; this saves time and increases reliability.
Yet another advantage is that the setup of the folding machine may correspond to the optimal imposition plan of the product that is to be manufactured.
The invention may be applied to folding machines for cut sheets and to folders for a web printing substrate, on roll.
Further advantages and embodiments of the present invention will become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to the following drawings without the intention to limit the invention thereto, and in which:
Fig. 1 shows a folding machine;
Figs. 2A - 2D show a buckle folder and the folding of a sheet therein;
Fig. 3 shows the relation between an imposition page and a final page;
Fig. 4 shows an imposition plan;
Figs. 5A and 5B show imposition plans.

DETAILED DESCRIPTION OF THE INVENTION

A folding machine folds flat printed sheets into sections, also called signatures. Fig. 1 shows a diagram of a folding machine 20 with three subsequent stages 21, 22 and 23. Sheet 14 is first folded in the first folding stage 21 along folding lines 26 (in Fig. 1, stage 21, only one of the five folding lines 26, drawn in dashed lines, is indicated by a reference sign); corner 13 of sheet 14 acts as a reference corner 13, i.e. the sheet 14 is fed with one or both of its edges that are adjacent to corner 13 against stops of folding stage 21. Then, in the second folding stage 22, the already folded sheet 14 is further folded along folding lines 27, perpendicular to folding lines 26 (in Fig. 1, stage 22, only one of the two folding lines 27, drawn in dashed lines, is indicated by a reference sign). Finally, the sheet 14 is folded in the third folding stage 23, along a folding line 26 perpendicular to folding lines 27. The obtained folded sheet 14 is called a section.
For each folding stage, a knife folder or a buckle folder (also called plate folder) may be used.
In a knife folder, a blunt-edged knife is set parallel with and above a slot formed by two rollers. The rollers revolve continuously so that when a sheet is placed over them and the knife descends, the sheet is caught between the rollers and carried away, a fold being made where the knife made contact. In practice the sheets are fed one at a time to stops, either by hand or by mechanical feeders, and are carried by moving tapes beneath the knife where they are precisely positioned mechanically for folding. The knife having descended, the sheet, now folded once, is carried by rollers and tapes to a second unit of knife and rollers where a second fold is made, then a third fold, etc., the folded sheets (now sections) being delivered to a stacker.
Figs. 2A and 2B show a buckle folder 30, also called buckle-plate folder 30. Such a folder 30 works on a different principle. As illustrated by Fig. 2A, sheet 14 is fed with its leading edge 16 between a pair of continuously revolving rollers 34, 35. The leading edge 16 is guided between a pair of two closely spaced plates 31 (also called buckle plates 31), the plane of the plates 31 being at an angle of 45° to the plane of feeding. The plates 31 are fitted with internal adjustable stops, that are in Fig. 2A set to one third of the length of sheet 14. When the leading edge 16 of sheet 14 hits these stops, further forward motion is prevented. The latter portion of sheet 14, however, is still being propelled forward by rollers 34, 35 and, being already bent at an angle of 45°, sheet 14 buckles at the point of entry to the plates 31. The buckle is gripped between the lower roller 35 of the roller pair 34, 35 and a third roller 36 in contact with it and the buckle passes between these rollers 35, 36, thus forming a fold. The folded edge is deflected into a second pair of plates 32. When the stops of this second pair of plates 32 are hit, a second buckle is formed, as shown in Fig. 2B. The folded sheet 14, now having a zig-zag form, is propelled by rollers 36, 37 and then by rollers 37, 38 to leave the buckle folder 30. In Fig. 2B, the third pair of plates 33 is bypassed and thus is out of use. The resulting fold is a zigzag fold which is shown in Fig 2D; the fold that was made by the first pair of buckle plates 31 is shown in Fig. 2C. The buckle folder 30 of Figs. 2A - 2B has two upper pairs of buckle plates 31, 33 and one lower pair of buckle plates 32. Current folding machines often have a first folding stage made up of four upper and four lower pairs of buckle plates. The available pairs of buckle plates may be set in use or may be bypassed, leading to different folds. Each pair of buckle plates in use produces an additional fold parallel to the first one.
In a preferred embodiment of the invention, the order of the folds and their location are represented in a way that is independent of the folding machine on which the folds will be performed, by means of so-called "folding formulae". A "folding formula" is a description that simply indicates the result that is to be achieved, e.g. "fold one third of the sheet upwards"; it does not indicate how a particular folding machine will attain this result. A folding formula is thus machine-independent.
A preferred notation of a folding formula is as follows: L3U1 for the fold shown in Fig. 2C and performed by the first pair of buckle plates 31 in Fig. 2A, wherein one third of sheet 14 is folded upwards. In formula (1), "L3" means that the length of sheet 14 is divided into three equal parts, while "U1" means that one of these parts, i.e. one third of sheet 14, is folded upwards (as shown in Fig. 2C). Which part of sheet 14 is folded upwards is defined by choosing a reference corner 13 with respect to which the folding operation is performed. In this document, the actual lower left corner of the - unfolded or folded - sheet 14 is always taken as the reference corner 13 (this is just a matter of choice; any corner might have been taken as the reference). In Figs. 2A - 2D, reference sign 17 indicates the original reference corner of sheet 14, which may differ from the actual reference corner 13. As shown in Fig. 2C, after the L3U1 fold, the original reference corner 17 is located in the middle of the folded sheet 14, while the new, actual lower left corner 13 of the folded sheet 14 is taken as the new, actual reference corner 13.
Subsequently, one third of sheet 14 is folded downwards, with respect to reference corner 13. The result of the two subsequent folds is shown in Fig. 2D and may be indicated by: L3U1D1 meaning that first one third of the sheet is folded upwards, "U1", and then one third of the sheet (i.e. one third of the original sheet length) is folded downwards, i.e. "D1" in formula (2).
The buckle-plate folder 30 shown in Figs. 2A - 2B has upper and lower pairs of buckle plates; as can be verified by means of Figs. 2A - 2D, an upper pair of buckle plates 31, 33 generates an upward fold, "U", while a lower pair of buckle plates 32 generates a downward fold, "D".
Since a folding formula simply indicates the result that is to be achieved, any fold or succession of folds, performed by a buckle folder, a knife folder or any kind of folder can be described by means of folding formulae. E.g. a folding stage wherein a sheet or a section is halved by means of a knife folder can be indicated by: L2U1
Folding formulae unambiguously describe how a sheet has to be folded, thus filling a gap in the prior art. Moreover, folding formulae are machine independent and can directly be used to set up a folding machine.
The corresponding imposition plan can be deduced from the folding formula by means of a simple algorithm, as is discussed below. For every folding formula, there is a corresponding imposition plan; a folding formula is thus also a representation of an imposition plan.
In an imposition plan as shown in Fig. 4 the individual pages P21, P20, ... P14 are arranged in such a way that after printing, folding and cutting, the pages follow one another in the correct order in the final product, such as a book. Fig. 4 shows so-called "imposition pages" 15; these are different from the final pages in the final product. In fact, extra space has to be added around the final pages in order to fold, collect/gather, bind and cut the product to the correct size in the final step. Fig. 3 illustrates the relation between a final page 18 and an imposition page 15: around a final page 18, a head trim 4, a foot trim 5 and spaces 6, 7 are added in order to obtain an imposition page 15. For products such as books, newspapers etc. units of two pages 18 are repeated in the imposition plan 10. The spaces 6, 7 are then calculated from spaces called the spine (which is the space, located at the spine of the book or newspaper, between two final pages), the front face trim, the front lip, the back face trim, the back lip, that are added to the right and/or to the left page of a two-page unit; however, this will not be discussed in detail since it is not necessary to understand the invention. In order to keep Fig. 3 readable, only two final pages 18 are shown in the drawing; in reality, each imposition page 15 contains a final page 18.
Returning now to Fig. 4, the shown imposition plan 10 contains 3 x 4 imposition pages 15: three imposition pages 15 are arranged next to each other in the length direction L of sheet 14, indicated by axis 11, while four imposition pages 15 are next to each other in the width direction W of sheet 14, indicated by axis 12. Axes 11 and 12 intersect in the reference corner 13 of sheet 14. Only four of the twelve imposition pages 15 are indicated by a reference sign, in order to keep the drawing readable. Typically, all folds in the imposition plan are located at a well defined fraction of the size of sheet 14: in Fig. 4, the fold lines are located at 1/3 and 2/3 in the length direction L and at 1/4, 1/2 and 3/4 in the width direction W. The location of the folds can thus indicated by giving the nominator of the fraction and the length and width of the sheet. The folding operation corresponding to the imposition plan 10 of Fig. 4, which includes the location of the folds, the folding direction and the folding order, can be indicated by: L3U1U1 W4U2U1 which means the following:
L3 : there are three imposition pages 15 in the length direction L of the imposition plan 10;
U1 : fold one part upwards; one "part" stands for one page in the length direction L, i.e. pages P16, P9, P4 and P21 taken together. After folding, the folded sheet or package has the size 4 x 2. The new reference corner is now the lower left corner of the package, i.e. the lower left corner of page P17;
U1 : fold again one part upwards in the length direction; the new reference corner is the lower left corner of the package obtained so far, i.e. the lower left corner of page P14. The size of the package is now 4 x 1;
W4 : there are four imposition pages 15 in the width direction W of the imposition plan 10. From now on, unless "L" would appear again, all folds apply to the W-direction;
U2 : fold two parts upwards, in the width-direction. The new reference corner is the lower left corner of the package obtained so far, i.e. the lower left corner of page P2. The size of the package is now 2 x 1;
U1 : fold one part upwards, in the width-direction. The new reference corner is the lower left corner of the package obtained so far, i.e. the lower left corner of page P23. The size of the package is now 1 x 1.
The pages on the folded package can now be numbered by hand, from "P1" to "P24" (both the front sides and the back sides of the individual pages of the folded package are numbered; there are thus 2 x 3 x 4 = 24 pages). In a preferred embodiment, the pages are numbered by means of a simple computer program simulating the folding process, the successive steps of which are given above. Unfolding the package, either by hand or by means of a computer simulation, returns the imposition plan 10 shown in Fig. 4 wherein the page numbers are indicated by "P21", "P20", etc. (remark: the page numbers on the back side of sheet 14 are not shown in Fig. 4).
Other imposition plans are shown in Figs. 5A and 5B. The folding operation corresponding to the imposition plan of Fig. 5A can be indicated by: L4U2U1 while the folding operation corresponding to the imposition plan of Fig. 5B can be indicated by: L6U2D2 W4U1D1U1 LD1 In formula (6), "LD1" is indicated. Instead, "L2D1" could also have been indicated; however, the size in the L-direction can be deduced from "L6U2D2" and thus does not have to be given again.
From what is set out above, it is clear that the first data, that indicate the folding order, may be represented in a machine-independent way by means of one or more folding formulae. In a method in accordance with the invention, preferably, second data are also generated that indicate a dimension of the product that is to be folded. Examples of these second data are: (a) the length (e.g. 1299 mm) and the width (e.g. 459 mm) of sheet 14; or (b) the length and the width of an imposition page 15 together with dimension information on the position of the folding lines 26, 27 relative to the position of the imposition pages 15; or (c) the position of one or more folding lines 26, 27. In examples (a) and (b), the positions of the folding lines 26, 27 may be determined from the folding formula and the second data; in example (c), the position of one or more folding lines 26, 27 is given directly.
As mentioned above, the first data are preferably machine-independent. It is preferred that the second data are also machine-independent. Advantageously, the machine-independent first and second data are then converted into machine-dependent third data, that may be sent to the folding machine, for its setup. Alternatively, the machine-independent data are sent to the folding machine and the conversion to machine-dependent data is done in the folding machine itself.
An advantage of a method in accordance with the invention is that all possibilities of the folding machine may be used. This results from the way in which the first data (e.g. the folding formulae) are generated; for more details, we refer to our patent application EP 02 102 092.0 entitled "Method for automatically determining an imposition plan", filed on the same day as the present application, and mentioned already above. From our patent application EP 02 102 092.0, it is also clear that a method for automatically generating data for setting up a folding machine in accordance with the invention is not based on predefined templates, or predefined data, but uses specification data of the product and folding machine data of the folding machine to calculate the data for setting up the folding machine. Thus, also for non-standard printing jobs, an easy and optimal set up of the folding machine becomes possible.
In a method in accordance with the invention, data are generated for setting up a folding machine 20. This "folding machine" may either be a real, existing machine or a "virtual" machine that does not exist but that has characteristics that are e.g. typical for a number of existing folding machines.
The invention may be applied to folding machines for cut sheets and to folders for a web printing substrate, on roll. For more details on the latter application, we refer to our patent application EP 02 102 092.0 mentioned above.
Those skilled in the art will appreciate that numerous modifications and variations may be made to the embodiments disclosed above without departing from the scope of the present invention.

List of reference signs

4 :: head trim
5 :: foot trim
6 :: space
7 :: space
10 :: imposition plan
11 :: axis
12 :: axis
13 :: actual reference corner
14 :: sheet
15 :: imposition page
16 :: edge
17 :: original reference corner
18 :: final page
20 :: folding machine
21 :: stage
22 :: stage
23 :: stage
26 :: folding line
27 :: folding line
30 :: buckle folder
31 :: buckle plate
32 :: buckle plate
33 :: buckle plate
34 :: roller
35 :: roller
36 :: roller
37 :: roller
38 :: roller

Claims

A method for automatically generating data for setting up a folding machine (20) for folding a product, the method comprising the steps of:

generating first data indicating a folding order;

generating second data indicating a dimension of said product.
The method according to claim 1 wherein said first and said second data indicate a position of a folding line (26, 27).
The method according to any one of the preceding claims, further comprising the steps of:

calculating an optimal imposition plan (10);

generating said first data based on said optimal imposition plan (10).
The method according to any one of the preceding claims, further comprising the step of:

generating said first data in a machine-independent format.
The method according to claim 4 further comprising the step of:

representing said first data as a folding formula.
The method according to claim 4 or claim 5, further comprising the step of:

converting said first data in said machine-independent format and said second data to third data in a machine-dependent format.
The method according to claim 6 further comprising the step of:

sending said third data to said folding machine (20).
The method according to any one of the preceding claims wherein said folding machine (20) is selected from the group of a folding machine (20) for cut sheets and a folder (20) for a web printing substrate.
A data processing system comprising means for carrying out the steps of the method according to any one of claims 1 to 8.
A computer program comprising computer program code means adapted to perform the method according to any one of claims 1 to 8 when said program is run on a computer.
A computer readable medium comprising program code adapted to carry out the method according to any one of claims 1 to 8 when run on a computer.