WO1993025427A1

WO1993025427A1 - Leaf-turning device of an index-cutting machine, and such a machine provided with a leaf-turning device

Info

Publication number: WO1993025427A1
Application number: PCT/SE1993/000517
Authority: WO
Inventors: Magnus Borud
Original assignee: Cutzius Ab
Priority date: 1992-06-10
Filing date: 1993-06-10
Publication date: 1993-12-23
Also published as: AU4366893A; SE505181C2; SE9201785L; SE9201785D0

Abstract

A leaf-turning device and an index-cutting machine, equipped with such a device, for thumb-indexing a thumb-index side of a document retained by a gripping device (2) on a holder (10), are disclosed. The leaf-turning device comprises an abutment (3) about which the document sheets are to be bent, and a leaf-turning reed (4) movable in relation to the abutment in order to retain the bent sheets against the abutment until they are to be released and indexed. The invention is distinguished by the abutment being movable in relation to the gripping device (2) in order to achieve successive release of the sheets retained by the leaf-turning reed (4) when the abutment (3) is moved away from the gripping device (2), and by a photocell device (7) being arranged at a distance from the abutment (3) for detecting markings on the document sheets in order to control the movements of the abutment (3) in relation to the gripping device (2) as a function of such detection.

Description

LEAF-TURNING DEVICE OF AN INDEX-CUTTING MACHINE, AND SUCH A MACHINE PROVIDED WITH A LEAF-TURNING DEVICE

The present invention relates to a leaf-turning device of an index-cutting machine, as well as an index- cutting machine equipped with such a leaf-turning device.

Index-cutting machines are used for thumb-indexing a thumb-index side of a document made up of a plurality of sheets. Sometimes, the document is referred to as a pad or block, especially if it is to be provided with or already has covers, to form a book, a catalogue or the like.

An index-cutting machine (thumb-index cutter) is used for cutting off circular, square or otherwise rectangular pieces from the long side of the sheets of e.g. a book, to make it easier for the reader to find the pages he is looking for. At present, there are semiautomatic thumb- index cutters, which have to be handled by an operator who manually turns over the pages to be jointly cut in a cut¬ ting or punching operation. Thus, the production rate is heavily dependent on the agility of the operator. An expe¬ rienced operator is expected to manage about 100 books each having 30 thumb indexes per hour. Efforts have been made to provide fully automatic thumb-index cutters in order to increase productivity, but existing such machines suffer from various drawbacks and cannot, for instance, be adapted to different paper grades. Thus, the properties vary a great deal from one paper to another. The grammage of the paper, ranging from the thinnest tissue paper to the thickest paperboard, influences the leaf-turning pro- perties, which are also affected by the properties of the fibres and the direction of the fibres in the paper. In some cases, the properties of the fibres may give a burr¬ like effect, so that the paper sheets tend to stick together. Those skilled in the art know that paper may sometimes behave in ways not foreseen. Thus, anyone skill¬ ed in the art will know that it is not easy to automati¬ cally and rapidly turn over different-grade paper for thumb-indexing. To obtain the properties desired by the user, the paper is sometimes coated with various sub¬ stances, which also may cause the paper to behave diffe¬ rently. Another factor to be considered is the humidity of the surrounding air. If the humidity is low and the air in addition has an unfavourable temperature, the paper may be charged with static electricity when processed, which often causes problems in paper-handling machines. Nowa¬ days, most printing offices and bookbinders' have climate- conditioned rooms, and static electricity thus does not cause any major problems.

A further difficulty in providing a fully automatic index-cutting machine or a leaf-turning device of such a machine is that conventional solutions used in the print- ing and bookbinder's business for providing a fully auto¬ matic thumb-index cutter would undoubtedly give a very slow machine. It is true that the production rate can be increased by parallel operation of several such machines, but this would of course be expensive. The crucial point when designing a rapid, fully automatic index-cutting machine is that the turning of the leaves should take place at a sufficiently high speed, and it should also be possible to flawlessly interrupt the leaf-turning opera¬ tion when the thumb-index sites have been found. Neither can one disregard the air resistance as a source of error in the handling of paper. When a thin paper is to be conveyed at high speed, it is important that the whole front of the paper is seized by a machine part. Otherwise, there is a considerable risk that a cor- ner of the paper is folded in the wrong direction by the air resistance. This may, at best, result in dog-ears at the paper corners and, at worst, in crushing interrupting the whole process.

An important aspect for achieving rapid handling is that the mass and the stroke length of all movable parts in a paper-handling machine should be kept low, enabling the machine parts to move at a comparatively high speed and be subjected to comparatively heavy acceleration and retardation.

Another aspect to be considered is that a more rapid and also more unreliable leaf-turning method, being slightly more deficient than other methods, may well be used, provided that the errors are accurately detected and rapidly corrected, or the books in which they are encountered are recycled to the beginning of the process. To give a comprehensive picture of the machine, the most important of the component parts are defined below. In-pile - where the operator puts the books or cata¬ logues to be thumb-indexed.

Feeder - conveys books from the in-pile and puts them in a path for further processing. Stabiliser - positions the books correctly and causes them to be in phase with the remainder of the machine.

Cover separator - folds away the covers so as not to be processed by the thumb-index cutter.

Leaf-turning device (thumb-index finder) - the com- plex device used for locating those parts of the book that are to be cut in one and same operation.

Cutting unit - the cutting section of the machine. Concentrator - closes the book prior to ejection. Ejector - positions the books correctly in the out- pile.

Out-pile - where the books prepared by the machine are placed. The operator or an automatic continuously removes the books one by one to make room for newly-cut books from the ejector. The market provides fairly satisfactory solutions for all the above component parts, save the leaf-turning device, and these can therefore be assembled without any major difficulties by those skilled in the art.

The critical component being the leaf-turning device, one object of the present invention is to provide one or more improved versions of known leaf-turning devices. German Patent Specification DE-A-10 91 082 discloses a device for turning the sheets of books in an index-cut¬ ting machine. The German device comprises a holder having a gripping device for clamping the document and gripping it along its spine opposite to the future thumb index; an abutment about which the document sheets are to be bent; a document-turning device for bending the document about the abutment; and a leaf-turning reed movable in relation to the abutment and adapted, when the sheets are being turn- ed, to be held in engagement with the bent document sheets in order to retain these until they are to be released and introduced into a cutting unit forming part of the index- cutting machine and disposed at a distance from the grip¬ ping device. In this leaf-turning device, the leaf-turning reed also serves as document-turning device after the sheets have initially been bent upwards by hand. The abut¬ ment is fixedly mounted on the holder, and the leaf-turn¬ ing reed, also serving as document-turning device, is mov¬ able along the stationary abutment, along the edges of the document sheets. When the leaf-turning reed moves towards the attachment of the abutment, the document sheets are released one by one from the document and drop down into the index-cutting machine. Since the distance between the free edge of the document sheet (the edge retained by the leaf-turning reed) and the curved portion of the abutment is small at the beginning of the leaf-turning operation, there is a risk that several document sheets are turned over at the same time owing to the springiness of the paper, which may lead to scrapping. As the sheets are turned over, this distance increases, which may lead to the last document sheets not dropping into the index-cut¬ ting machine since the springiness of the paper is insuf¬ ficient to overcome the force of gravity urging the sheets against the abutment. The known leaf-turning device not only suffers from the above-mentioned irregular and unreliable leaf-turning function, but also is uncapable of repeatedly and reliably leaf over the right number of document sheets for thumb-indexing.

Another object of the invention is, therefore, to provide a leaf-turning device of an index-cutting machine, which is able to rapidly and at a uniform speed leaf over the number of sheets to be cut in each cutting or punching operation.

A further object of the invention is to provide an index-cutting machine operating at a considerable speed and with high accuracy, being provided with such a leaf- turning device.

Yet another object of the invention is to provide a leaf-turning device ensuring that the right number of sheets to be cut are turned over. A further object still is to provide such a leaf-turning device which itself is capable of correcting any errors occurring during the leaf-turning operation.

Finally, another object of the invention is to pro¬ vide a leaf-turning device that is easily adapted to dif- ferent thicknesses, grades and sizes of the sheets to be indexed.

According to the invention, one or more of these objects are attained by a leaf-turning device and an index-cutting machine as defined in appended claims 1 and 10, respectively. Especially preferred embodiments are stated in the appended subclaims.

To exemplify the invention, preferred embodiments thereof will now be described with reference to the accompanying drawings, in which Figs la-Ik are a series of views showing how a document to be leafed over is arranged in a gripping device and illustrating the subsequent leaf¬ ing sequence in a first embodiment of the leaf-turning device according to the invention; Fig. 2 is a schematic perspective view showing the main components of an embodiment of the leaf- turning device according to the invention; Fig. 3 is a detailed side view illustrating an initial stage of the leaf-turning operation; Fig. 4 is a view similar to that of Fig. 3 and illu¬ strates a later stage of the leaf-turning ope- ration;

Fig. 5a is a side view of an embodiment of means for supporting the sheets to be cut, the support means being here unfolded; Fig. 5b is a view of the support means when folded up; Fig. 6a is a view similar to that of Fig. 5a but illu¬ strates an alternative embodiment of the sup¬ port means unfolded; Fig. 6b is a view of the support means of Fig. 6a fold¬ ed up; Fig. 7 is a schematic view of parts of another embodi¬ ment of the leaf-turning device and the index- cutting machine according to the invention; Fig. 8 schematically illustrates different setting positions for the leaf-turning device of Fig. 7, which is thus adapted to documents or book blocks of different thicknesses; and Figs 9a-9f are a series of views showing how the document to be leafed over is arranged in a gripping device and illustrating the subsequent leaf- turning sequence in the embodiment of the inventive leaf-turning device and index-cut¬ ting machine of Figs 7 and 8. Fig. 2 shows an embodiment of the leaf-turning device according to the invention. This device is intended to be used together with an index-cutting machine for thumb- indexing one side of a document made up of a plurality of sheets. The leaf-turning device comprises a gripping device 2 in which the document 8 is clamped by retainer means 16. During the cutting operation, the gripping device 2 is fixed in a certain position in relation to a cutting unit 1 forming part of the index-cutting machine, but it can be moved in relation thereto when the machine is to be adjusted to documents of different sizes. An abutment 3 is movable in the horizontal direction towards and away from the gripping device 2 and, consequently, the cutting unit 1. A photocell device 7 or the like is arranged to sense a marking 40 provided at the free edge of the back of the first sheet to be retained until the next cutting operation. The movements of the abutment 3 are controlled by the photocell device 7, as will be accounted for in more detail below. A leaf-turning reed 4 is applied against the still uncut document sheets bent about the abutment 3, in order to hold the sheets in engagement with the abutment until they are to be released (turned or leafed over) one by one to be introduced into the cutting unit 1. A safety stop 5 cooperates with the leaf-turning reed 4 for retaining the sheets not to be released, and an intermediate stop 6 is arranged to ensure that the right number of sheets is introduced into the cutting unit 1. The sheets 21 to be cut, i.e. the sheets released by the leaf-turning reed 4, the safety stop 5 and the intermediate stop 6, may, if required, be supported by a support means 9 which, after the indexing operation, lets the sheets drop past the cutting unit, as indicated by reference sign 15, designating sheets that have been cut. After the cutting or punching of each thumb index, the leaf-turning device and the cutting unit 1 are dis¬ placed in the longitudinal direction in relation to one another through a distance corresponding to the space between the punched tab and the next tab.

By the term "sheet" is here meant leaves or sheets of paper, paperboard, board, plastic foil and the like, which show flexibility and are intended to form a document, e.g. a book or a catalogue. Further, the term "document" here relates to a plurality of sheets, e.g. the sheets of a book or a catalogue. Figs 3 and 4 illustrate the leaf-turning device in more detail. The document 8 is retained in the gripping device 2 by means of several retainer means 16 which, by a driving means 41 schematically illustrated in Fig. 3, are pressed against the document 8 at a point close to its spine. The document 8 has left the cover separator for indexing, and will, after indexing, be transferred to the concentrator, as above. The leaf-turning reed 4, which is adapted to move towards the abutment 3 when the leaves are being turned over, is, by a pivot pin 42, pivotally con¬ nected to a holder 12 also supporting the abutment 3. In the illustrated embodiment, the leaf-turning reed 4 and the photocell device 7 are both supported by an arm 17 in a carrier device 14 to which the safety stop 5 is attach¬ ed. If deemed appropriate, the photocell device 7 may of course be disposed elsewhere, e.g. on the intermediate stop or the abutment. By a pivot pin 43, the safety stop 5 is pivotally fixed to the arm 17 in the carrier device 14 and is moved towards and away from the leaf-turning reed 4 and the sheets retained thereby by means of an electromag¬ net or a step motor 18 which, by a pivot pin 44, is pivo¬ tally connected to the arm 17 and, by a pivot pin 45, is pivotally connected to the safety stop 5. Moreover, the carrier device 14 is pivotally fixed in the frame 12 by the pivot pin 42 and is operated with the aid of a step motor 19 (or the like) connecting the frame 12 to the arm 17. The frame 12 is in turn pivotally suspended from a frame holder 13 by means of a driving device, e.g. a step motor or a pneumatic cylinder, which is generally desig¬ nated 20 and which is pivotally connected to the frame holder 13 and the frame 12 by pivot pins 46 and 47, respectively, to allow the frame 12 to rotate or pivot in relation to the frame holder 13 (cf. Figs 3 and 4). Finally, the frame holder 13 is arranged so as to be slid- able in the horizontal direction in a holder 10 on which the gripping device 2 is mounted. The frame holder 13 can be displaced in relation to the holder 10 e.g. by a step motor 48 driving a screw 49 engaging a nut 50 on the frame holder 13. Also the intermediate stop 6 is supported in SUBSTITUTESHEET the holder 10 so as to be slidable towards and away from the cutting unit 1 and towards and away from the abutment 3. This displacement is achieved by a motor 51 schemati¬ cally illustrated in Fig. 3. A return belt 22 travels from the lowermost portion of the intermediate stop to a return means 28 provided on the intermediate stop, e.g. a piston and cylinder unit, as shown in Fig. 3.

When extending the return means 28 to the left in Fig. 3, the released sheets are pressed back against the abutment, and the leaf-turning reed can thus be raised to again grip these sheets. The holder 10 may be displaceable and supported by e.g. a robot (not shown), in which case the cutting unit 1 is stationary. Alternatively, the holder 10 can be stationary and the cutting unit 1 be dis- placeable. The relative motion between the holder 10 and the cutting unit 1 is needed when the index-cutting machine is to be adjusted to documents of different widths (the holder and the cutting unit being displaced towards and away from one another) and when the document is to be moved in relation to the cutting unit along the thumb- index edge between successive cutting operations (by means of the motor 52 shown in Fig. 2).

In Figs 3, 4 and 5a, the folding support means 9, provided between the gripping device 2 and the cutting unit 1, is shown in extended or unfolded position, in which it supports the sheets 21 to be cut and has let the cut sheets 15 pass by. Alternatively, the cut sheets 15 can be entrained beyond and down under the cutting unit 1 by suitable means (not shown). Fig. 3 illustrates an initial stage of the leaf-turn¬ ing operation, while Fig. 4 illustrates a later stage, in which fewer sheets of the document 8 remain to be cut. When comparing the two Figures, it is clear that, during the leaf-turning operation, the abutment 3 has moved fur- ther away from the gripping device 2 and closer to the cutting unit 1 and that the leaf-turning reed 4 has moved closer to the abutment 3. In this embodiment of operating the leaf-turning device, the leaf-turning reed has, in addition, been pivoted with respect to the clamped portion of the document. Alternatively, the sheets can be turned by translatory motion only between the frame holder 13 and the holder 10 (by means of the step motor 48) or by pivo¬ tal motion between the frame 12 and the frame holder 13 (by means of the driving motor 20). In both instances, the leaf-turning reed 4 will move relative to the free edge of the bent document and release the document sheets one by one until the photocell device 7 detects a marking 40 on the back of the first sheet of the next thumb index, and then stops the relative motion or motions.

Figs 5a and 5b illustrate a preferred embodiment of the support means 9 comprising a plurality of substantial- ly U-shaped, bent sections whose flanges 23 are pivotally connected to a pair of attachments 24 between and below the gripping device 2 and the cutting unit 1. Opposite flanges 23 are interconnected by a horizontal portion (not shown). Together, these horizontal portions support the sheets 21 to be cut. In Fig. 5b, the support means 9 is folded up, and the cut sheets 15 have been allowed to drop (or be entrained) to a position below the cutting unit, but are still retained by the gripping device 2.

Figs 6a and 6b illustrate an alternative embodiment of the support means 9, in which the earring surface of the support means is designed as an accordion-folded sheet 25 supported by a pair of arms 26. At one end, the arms are interconnected by a transverse section 27, and at the other end, the arms are connected to associated pivotal flanges 23. Between the ends, the arms 26 are mounted in the cutting unit 1. Fig. 6b shows the folded up or con¬ tracted position of the support means 9, in which the flanges 23 have been pivoted away from the cutting unit 1 (and the leaf-turning device), the sheet 25 having been maximally contracted and folded towards the cutting unit 1 and the cut sheets 15 having been allowed to drop from the cutting unit, as shown in Fig. 5b. In Fig. 6a, the folded sheet 25 of the support means has again been extended in order to support further sheets 21 released by a rod 11 which, in this embodiment, also performs the function of the leaf-turning reed. This embodiment is not as advanta- geous as that comprising a separate leaf-turning reed. Thus, the rod 11 used in this embodiment can be replaced with a leaf-turning reed of the type found in other embo¬ diments described.

The function of the leaf-turning device will now be explained in more detail with reference to Figs la-Ik. In Fig. la, the document 8 clamped in the gripping device 2 has been removed from the cover separator by a robot or the like and introduced into the leaf-turning device. The document is brought into engagement with the abutment 3 and a document-turning device 11, e.g. a rod. By a relative, arcuate motion between, on the one hand, the document-turning device 11 and, on the other hand, the document 8 and the gripping device 2, the document is bent about the abutment 3 to the initial position (Fig. lc). The document-turning device 11 may be a fixed rod, in which case the entire leaf-turning device is movable and presses the document 8 against the document-turning device so that an arcuate movement of the leaf-turning device causes the document to be turned about the abutment 3 to the initial position (Fig. lc). Alternatively, the leaf- turning device is stationary, and a movable document-turn¬ ing device 11 is then used and is taken along an arcuate path, thereby achieving the same result. Fig. lb shows an intermediate position between the initial position in Fig. la and the leaf-turning position in Fig. Ie, i.e. the position of the document when the leaf-turning operation may begin. In Fig. Id, the leaf-turning reed 4 has been brought into engagement with the foremost document sheet so as to hold the document bent about and engaged with the abutment, enabling the removal of the document-turning device 11 (cf. Fig. Ie). The sheets are turned in the following way. The abut¬ ment 3, suspended from the frame holder 13, is moved away from the gripping device 2 and towards the cutting unit 1 by means of the driving motor 48 of the frame holder, the distance between the holder 10 and the cutting unit 1 being maintained substantially constant. Simultaneously, the leaf-turning reed 4 is kept stationary in relation to the gripping device 2, so that the abutment 3 pushes the free edge of the document sheets beyond the leaf-turning reed 4, the document sheets being thus released one by one. When the printing-ink marking 40, or some other suit¬ able marking, provided on the side of the document sheets facing the leaf-turning reed 4, is detected by the photo¬ cell device 7, the forwardly-directed movement of the driving motor 48, and consequently of the abutment 3, is stopped. Preferably, the abutment 3 is moved slightly backwards in order to relieve the pressure on the detect¬ ed, marked sheet and prevent it from being inadvertently turned over. Simultaneously, the photocell device 7 acti- vates the electromagnet 18, and the safety stop 5 is thus brought into engagement with the sheet at issue, thereby to retain it in cooperation with the leaf-turning reed 4 (see Fig. lh). The intermediate stop 6 is actuated and has intercepted the sheets which have been released from the leaf-turning reed 4 (cf. Fig. lh) and are to be cut. If the photocell device 7 indicates that the marked sheet has been uncovered, the intermediate stop 6 is returned to its resting position (shown in Fig. Ii) and the sheets 21 to be cut are allowed to drop onto the support means 9 and into the cutting unit 1 (see especially Figs Ik and 3).

After the sheets 21 have been cut, the support means 9 is folded up, and the cut sheets 15 still retained by the gripping device are permitted to drop below the cut¬ ting unit. Thereafter, the support means is returned to the position shown e.g. in Fig. 5a, and the intermediate stop 6 is actuated in order to occupy the position shown in Figs lg and 3. Then, the document sheets that are the next to be cut are turned over in the manner described' above until the photocell detects the next marking on the back of a sheet, and the above sequence is repeated.

Assuming, for the sake of simplicity, that a 200-page book is to be given 20 index tabs containing 10 pages each. This requires 20 printing-ink markings indicating the boundaries between the index tabs. Further, the cut¬ ting unit has to perform 20 cutting operations. It should here be observed that books to be thumb-indexed are always well trimmed at the edges, giving exceptionally even sur¬ faces along the document edges. When the abutment 3 moves forwards and away from the gripping device 2 at a speed of 1-2 mm/s, the document sheets will be pushed one by one beyond the leaf-turning reed at a rate of approxiamtely 20 sheets/s.

Should the photocell device 7 fail to indicate a marking 40 after the safety stop 5 has been brought into engagement with the document 8, this means that one or more sheets have been incorrectly released from the leaf- turning reed 4 and intercepted by the intermediate stop 6 (see Fig. lh) together with the correctly turned sheets 21 to be cut. The sheets incorrectly turned and held by the intermediate stop thus have to be returned and leafed over anew in view of obtaining the right index tab. The sheets are returned by means of the return belt 22

(Fig. 3). Thus, the return means 28 on the intermediate stop is actuated and telescopically projected to the left in Fig. 3, the return belt being pressed against the intercepted sheets so as to turn these about the abutment 3 once again. Before this operation, the abutment 3 has been moved backwards slightly to the left in Fig. 3 and the carrier device 14 has been raised by means of the step motor 19, so that the leaf-turning reed 4 and the safety stop 5 have been moved out of the way of the sheets that are to be returned to their previous position bent about the abutment 3. Then, the carrier device 14 is lowered, the return device 22, 28 is brought to its inoperative position (see Fig. 3) and the leaf-turning operation pro¬ ceeds as above.

When the whole document 8 has been cut, it is con¬ veyed to the concentrator for further handling. In the embodiment of the leaf-turning device and the index-cutting machine according to the invention shown in Figs 7-9f, an abutment 54 is arranged on an arm 55 which is pivotable about a pivot pin 56 by a motor 57 schema¬ tically illustrated in Fig. 7 only. The pivot pin 56 is fixed to a frame 58. An arm 59 is also mounted on the pivot pin 56, so as to pivot towards and away from the arm 55 and the abutment 54 thereon. This pivotal movement is achieved by means of a motor 60 schematically illustrated in Fig. 7 only. At its free end, the arm 59 supports a leaf-turning reed or tongue 61, with which it is intended to engage a document 10 turned about the abutment 54. The arm 59 is further provided with a holder 62 for a photo¬ cell device 63. The frame 58 is pivotally connected (not shown in detail) to a holder 64 to which a gripping device 65 for the document 10 is also attached. By means of a motor 66, shown in Fig. 8 only, the frame 58 is pivotable between the positions indicated by dash-dot lines and con¬ tinuous lines in Fig. 8. By means of a motor 67, shown in Fig. 8 only, the frame 58 can be displaced in a transla- tory motion relative to the frame holder 64 substantially straight ahead towards a cutting unit 1. By means of a motor 68, shown in Fig. 8 only, the entire frame holder 64, the frame 58 therein and the frame components are dis¬ placeable perpendicular to the plane in which the frame 64 is displaceable by the motor 67 (upwards and downwards in Fig. 8). This movement achieved by the motor 68 serves to displace the document relative to the cutting unit 1 (see Figs 9d-9f) between successive cutting operations, so that cutting takes place substantially perpendicular to the front and back of the document when lying flat. Finally, there is provided yet another servomotor 69, shown in Fig. 8 only, serving to displace the frame 64, and all the components thereon, perpendicular to the plane of the drawing, i.e. along the cutting unit for adjusting the leaf-turning device in relation to the cutting unit between successive cutting operations. Figs 9a-9f show the leaf-turning device and the cut¬ ting unit 1 in different positions occupied during a machine cycle. Fig. 9a illustrates an initial position, in which the document 8 is retained by the gripping device 65 on the frame holder 64. The frame 58 here occupies its initial position relative to the frame holder 64 and is applied with the abutment 54 against the document 8. The frame holder 64 and all the components thereon, held in the position shown in Fig. 9a, are caused by a motor (not shown here) to perform a circular movement about a sta- tionary document-turning device 70 corresponding to the document-turning device 11 in the embodiment described above. This arcuate movement is indicated by an arrow 71 in Figs 9a and 9b. The turning movement continues until the document-turning device 70 has brought the document 8 to the position shown in Fig. 9c. In this position, the arm 59 is swung downwards towards the arm 55 by means of the motor 60, so that the leaf-turning reed 61 comes into engagement with the outermost sheet of the document 8. Then, the entire frame holder 64, and the components sup- ported thereby including the document, are transferred to a leaf-turning station, where the document occupies the correct position in view of the leaf-turning operation. This position is shown in Fig. 9d. The sheets are then turned by the frame 58 being displaced to the right rela- tive to the frame holder 64, as illustrated by the arrow 72 between Figs 9d and 9e. By this displacement of the frame 58 relative to the gripping device 65, a number of sheets of the document 8 will drop down towards the die of the cutting device, as illustrated in Fig. 9e for the sheets 21. The forward movement of the frame 58 and the abutment 54 is stopped in the manner described above, when the photocell device 63 detects a marking (corresponding to the marking 40 in Fig. 2). Thereafter, the sheets 21 are cut and dropped to a position below the cutting unit, as are the sheets 15 in Fig. 9f. The frame 58 is then moved forwards relative to the holder 65, as indicated by the arrow 73 between Figs 9e and 9f, so as to turn the next group of sheets to be cut. This cutting order is then repeated until all groups of sheets have been provided with index tabs and the cutting unit has come to occupy the position shown in Fig. 9f. Between the different cut- ting stages, represented by the transition between Figs 9d and 9e and between Figs 9e and 9f, the frame 64 and the components thereon are displaced downwards, as seen in Figs 9d-9f, by means of the motor 68 (see Fig. 8). Between each cutting stage, the cutting unit, and consequently the document 8, is displaced perpendicular to the plane of the drawing by means of the step motor 69 (Fig. 8) in order to position the document correctly relative to the cutting unit for each index tab.

It goes without saying that the invention is not restricted to the embodiments described above and shown in the drawings, and thus may be modified in many ways within the scope of the appended claims.

Claims

1. A leaf-turning device which is designed for an index-cutting machine for thumb-indexing a thumb-index side of a document (8) made up of a plurality of sheets, and which comprises a holder (10) having a gripping device (2, 65) for clamping the document along its spine opposite to the future thumb index; an abutment (3, 54) about which the document sheets are to be bent; a document-turning device (11, 70) for bending the document about the abut¬ ment (3, 54); and a leaf-turning reed (4, 61) movable in relation to the abutment (3, 54) and adapted, when the sheets are being turned, to be held in engagement with the bent document sheets in order to retain them until they are to be released and introduced into a cutting unit (1) forming part of the index-cutting machine and disposed at a distance from the gripping device (2, 65), c h a r ¬ a c t e r i s e d in that the abutment (3, 54) is movable in relation to the gripping device (2, 65) and connected to a driving device (48, 67) for moving the abutment in relation to the gripping device and causing the bent sheets retained by the leaf-turning reed (4, 61) to be successively released when the abutment is moved away from the gripping device (2, 65), and that a photocell device (7, 63) is arranged at a distance from the abutment (3, 54), towards which it is directed for detecting markings (40) on document sheets retained by the leaf-turning reed, and is connected to the driving device (48, 67) of the abutment so as to stop the movement of the abutment away from the gripping device (2, 65), and thus stop the leaf- turning operation, when detecting a marking (40) on a marked document sheet.

2. A leaf-turning device as set forth in claim 1, c h a r a c t e r i s e d in that the abutment (3, 54), the leaf-turning reed (4, 61) and the photocell device (7, 63) are arranged in a common frame (12, 58), to which the driving device (48, 67) of the abutment (3, 54) is con¬ nected in order to move the frame (12, 58) in relation to the holder (10, 64).

3. A leaf-turning device as set forth in claim 2, c h a r a c t e r i s e d in that the frame (12, 58) com¬ mon to the abutment (3, 54), the leaf-turning reed (4, 61) and the photocell device (7, 63) is pivotally and dis- placeably fixed on a frame holder (13, 64).

4. A leaf-turning device as set forth in claim 3, c h a r a c t e r i s e d in that the frame holder (13,

64) is displaceably fixed on the holder (10) in order to displace the abutment (3, 54) in a plane substantially parallel to a plane passing through the gripping device (2, 65) and the cutting unit (1).

5. A leaf-turning device as set forth in any one of claims 1-4, c h a r a c t e r i s e d in that the leaf- turning reed (4, 61) and the photocell device (7, 63) are arranged on a common carrier device (14, 59) pivotally supported by the frame (12, 58) common to the abutment (3, 54), the leaf-turning reed (4, 61) and the photocell device (7, 63).

6. A leaf-turning device as set forth in any one of claims 1-5, c h a r a c t e r i s e d in that a safety stop (5) is arranged to move together with the leaf- turning reed (4) and is connected to a driving motor (18) controlled by the photocell device (7) for pivoting the safety stop (5) in relation to the leaf-turning reed (4) and into engagement with said marked sheet of the document (8) when detecting the marking (40) of this sheet.

7. A leaf-turning device as set forth in any one of claims 1-6, c h a r a c t e r i s e d in that an inter¬ mediate stop (6), which is displaceable substantially transversely of the direction of movement of the abutment (3), is arranged between the safety stop (5) and the cut- ting unit (1).

8. A leaf-turning device as set forth in claim 7, c h a r a c t e r i s e d in that the intermediate stop (5) is so arranged on the holder (10) as to be movable towards and away from the cutting unit (1), and operably supports a return device (22, 28).

9. A leaf-turning device as set forth in any one of the preceding claims, c h a r a c t e r i s e d in that a folding support means (9) is arranged between the grip¬ ping device (2) and the cutting unit (1) for supporting and then releasing the sheets (21) of the document (8) that are to be cut.

10. An index-cutting machine which is designed for thumb-indexing a thumb-index side of a document (8) made up of a plurality of sheets, and which comprises a cutting unit (1) and a leaf-turning device as set forth in any one of the preceding claims, the leaf-turning device and the cutting unit being connected to a driving device (52, 69) for relative displacement of the leaf-turning device and the cutting unit in a direction substantially parallel to the thumb-index side of the document.