WO1999001263A1

WO1999001263A1 - Sheet aligning device and sheet treating device provided with the same

Info

Publication number: WO1999001263A1
Application number: PCT/SE1998/001254
Authority: WO
Inventors: Sture Stenson Lindvall; Kalle Eino Aksberg
Original assignee: Arno Maskin Ab
Priority date: 1997-07-01
Filing date: 1998-06-26
Publication date: 1999-01-14
Also published as: SE509814C2; SE9702549L; AU8136398A; SE9702549D0

Abstract

The invention relates to a sheet-aligning device and a sheet-treating device provided with the same. The sheet-aligning device is intended for a leaf-turning device (23) and is arranged in a subframe (20) in the sheet-treating device. The sheet-aligning device has a holder (24) intended for a bundle of sheets to hold the spine of the bundle of sheets in an essentially horizontal position. A supporting rod (31) is used to support a hanging portion of the bundle of sheets. According to the invention, this supporting rod is formed with an approximately parabolic supporting surface (41, 43) engaging the bundle of sheets (25). Sheet bundle lifting means (29, 30) are available to successively raise the bundle of sheets (25) upwards in the subframe (20), such that the underside of a just turned sheet is in a predetermined vertical position relative to the subframe. With the aid of supporting rod operating means (32-39), the supporting rod (31) is pivoted such that the supporting surface (41, 43) of the supporting rod engages the lowermost sheet in the bundle of sheets with curved surface portions having an increasing radius of curvature the thinner the bundle of sheets during the turning of the sheets, and such that each sheet which is the next to be turned is held in essentially the same curved shape.

Description

SHEET ALIGNING DEVICE AND SHEET TREATING DEVICE PROVIDED WITH THE SAME

The present invention relates to a sheet-aligning device intended for a sheet-treating device, for instance a so-called index-cutting machine.

There are many occasions where it is important that individual sheets or individual leaves in a bundle of sheets be aligned correctly relative to some type of sheet-treating equipment. One occasion is when sheets in a bundle of sheets are to be provided with pagination or marking in a given position, for instance in a corner. Another occasion is when the sheets in a bundle of sheets are to be formed with turning tabs or notches as is the case in many catalogues. A third occasion is when the sheets in a bundle are to be counted by means of a combined counter and leaf-turning device, which engages a corner of the sheets and must then be accurately aligned with corners of successive sheets for a correct result to be achieved in the leaf-turning/counting operation.

Leaf-turning devices of this type are available for various purposes, e.g. for counting the number of notes or documents in a bundle of notes or documents, or for counting a predetermined number of leaves or sheets in a book block or catalogue block in connection with the forming of a thumb-index along one edge of the block. Such thumb-indexes are produced by a so-called index- cutting machine (or thumb index-cutter) forming notches along a thumb-index side of a document comprising one or more sheets. The document is sometimes referred to as a block, particularly if it is to be fitted with or is already fitted with covers to form a book, a catalogue or the like.

Prior-art leaf-turning devices for these purposes operate either entirely mechanically or on the basis of vacuum technology. As an example of mechanical leaf-turning devices mention can be made of a device according to PCT Publication WO 93/25427. In this prior-art device, the stitched or bound block of sheets is bent round a displaceable support, making the free edges of the bent sheets assume an offset position relative to one another, whereby the sheets retained in position by a finger means may be dropped one by one onto a sheet-block support while at the same time the number of released sheets is counted. When the desired number of sheets has been released and formed a group of sheets on top of a sheet support, the required notches are produced by removing sheet material in a cutting or punching operation performed along the sheet edge. This procedure is then repeated a requisite number of times to form the requisite number of thumb- index notches depending on the intended number of groups of sheets or leaves in the book block or catalogue block. Devices of this prior art type function very well after setting of the machine for a particular paper grade and thickness, but require much from the operators in the way of setting accuracy and skill.

It has therefore been suggested that a bundle of sheets be clamped along one edge and the rest of the bundle of sheets be allowed to hang down over a rod, such that the opposite free edges of the sheets will be offset relative to each other to make it possible to count them by means of a sheet counter. An example of this technique is disclosed in the published Swedish Patent Application 9502839-5, according to which a suction nozzle is used to hold by suction the outermost of the hanging sheets and according to which a tongue-shaped element and a wiping rod projecting in the same direction from the sheet counter are used by the wiping rod being made to perform a circular motion round the tongue-shaped element to forcibly separate the sheet held by the suction nozzle from the rest of the bundle of sheets. A drawback of this known device, however, is that the uppermost (outermost) sheet is not always in exactly the same position relative to the suction nozzle and the counter although the sheet counter and the bundle of sheets are relatively moved towards each other to compensate for the thickness of the just turned sheet.

In a suggestion not yet published (Swedish Patent Application 9602653-9, now SE-C-506945) , this problem has been solved by means of a leaf-turning device for turning and counting a stack of sheets, said leaf-turning device having a leaf-turning nozzle for holding by suction a sheet and moving this away from the rest of the stack. A lifting rod is movable relative to the stack and the leaf-turning nozzle to be inserted between a sheet held by suction by means of the nozzle and the rest of the stack and to pull this sheet away from the nozzle and move the same to an intermediate storage position. The lifting rod is arranged to move in a round path, within which the leaf-turning nozzle is located and which extends between the leaf-turning nozzle and the stack. A blow-off nozzle is arranged to direct a jet of air towards the edge of the sheet raised by the leaf-turning nozzle to release any entrained, additional sheets before the lifting rod pulls away the counted sheet from the nozzle. In this device, the free parts of the bundle of sheets hang down over a rod which in a shown embodiment has a given diameter. While turning the leaves, a relative motion occurs between this rod and the bundle of sheets with a view to trying to hold the outermost free sheet in essentially the same vertical plane although the sheets are being turned and the bundle of sheets becomes thinner and thinner. However, it has been found that also this device in its shown embodiment suffers from drawbacks by the fact that the radius of curvature and, thus, the outer contour of the remaining, not yet turned/count- ed part of the bundle of sheets changes as the turning of leaves proceeds. This results in turn in difficulties of ensuring the exact position of this outermost sheet rela- tive to the leaf-turning device, which may cause deficiencies in the leaf-turning result.

The known devices for alignment of the sheets in a bundle of sheets during the leaf-turning operation thus suffer from various drawbacks; for instance, it is difficult to achieve a correct alignment of the sheets relative to a leaf-turning device.

An object of the present invention therefore is to improve the prior-art sheet-aligning devices and sheet- treating devices and provide a better and safer alignment of the sheets relative to the leaf-turning device.

A further object of the invention is to provide a better and safer alignment of the sheets relative to the leaf-turning device and a sheet-treating device also when turning leaves and treating bundles of sheets with different sheet thickness.

According to the invention, these and other objects are achieved if a sheet-aligning device and a sheet- treating device are designed as stated in independent claims 1 and 5. The dependent claims recite particularly preferred embodiments of the sheet-aligning and sheet- treating devices according to the invention.

Summing up, the invention concerns on the one hand a sheet-aligning device for a leaf-turning device and, on the other hand, a sheet-treating device provided which such a sheet-aligning device. The sheet-aligning device comprises a subframe included in the sheet-treating device and has a holder for a bundle of sheets to hold the spine of the bundle of sheets in an essentially hori- zontal position. A supporting bar is used to support a hanging portion of the bundle of sheets. According to the invention, this supporting rod is formed with an approximately parabolic supporting surface engaging the bundle of sheets. Sheet bundle lifting means are arranged to successively raise the bundle of sheets upwards in the subframe, such that the underside of a just turned sheet is in a predetermined vertical position relative to the subframe. By means of supporting rod operating means, the supporting rod is pivoted such that the supporting surface of the supporting rod engages the lowermost sheet in the bundle of sheets with curved surface portions of an increasing radius of curvature the thinner the bundle of sheets during the turning operation, and such that each sheet which is the next to be turned, is held in essentially the same curved shape.

The invention is based on the knowledge that the most accurate alignment could be achieved if, by a suitable design of the sheet-aligning device, it would be possible to permanently keep the same profile of curvature of a sheet, which is the next to be turned in the hanging, not yet turned part of the bundle of sheets since the guiding of the various parts of the sheet- aligning device relative to the leaf-turning device would then be considerably simplified.

On the basis of this knowledge, the supporting rod, seen in cross-section, has therefore been formed with a supporting surface profile which is approximately parabolic with a radius of curvature varying from a small radius of curvature to a large radius of curvature, the smallest radius of curvature corresponding to the radius of curvature of the lowermost sheet in the bundle of sheets when the supporting rod supports a bundle of sheets which has not been turned, and the largest radius of curvature corresponds to the radius of curvature of the lowermost sheet in the bundle of sheets when the lowermost sheet at the same time constitutes the only remaining, not yet turned sheet in the bundle of sheets. A particularly preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which Fig. 1 is a perspective view of a sheet-treating device and a sheet-aligning device according to the invention, Fig. 2 is a perspective view of parts of a carriage included in the sheet-treating device, Fig. 3 is a perspective view of parts of this carriage in one position, Fig. 4 shows the same parts as in Fig. 3 although in a different position, Figs 5-8 show in succession certain parts of the sheet- treating and sheet-aligning devices in different positions while turning a bundle of sheets to illustrate the inventive idea, and

Fig. 9 is a perspective view of the same parts as in Figs 5-8. Fig. 1 shows the major part of a sheet-treating device according to the invention. The device has a frame 10, on which a sheet-treating device is mounted. Since the illustrated embodiment of the invention has the form of an index-cutting machine, the sheet-treating device is a cutting assembly 11 having a lower cutting blade 12 which is fixed in position relative to the frame 10. The upper cutting blade 13 of the cutting assembly is not shown in Fig. 1 but is mounted on a column 14 to move towards and away from the lower cutting blade 12. A driving engine with a shaft 15 is available to perform these motions of the upper cutting blade 13. Such cut- ting assemblies 11 are known and therefore need not be described in detail in this connection.

The frame 10 supports a movable frame member 16 which can be moved towards and away from the cutting assembly 11 to control the depth of the thumb-index notch which is to be formed by means of the cutting assembly. With a view to restricting the possibility of the frame member 16 moving in the direction of the cutting assembly, there is at least one buffer 17 for cooperation with a stop lug 18. The stop lug is fixed in position relative to the frame 10 and, thus, the cutting assembly 11.

In the frame member 16 a carriage 20 is mounted to be moved in a path extending in parallel with the lower cutting blade 12. To this end, the carriage 20 has rollers 21 which run in a roller path 22 at the upper end of the frame member 16. The movability of the carriage relative to the cutting assembly 11 is used to determine the desired positions of the thumb-indexes. The movement of the carriage is therefore carried out in steps which are dependent on the relative distance of successive thumb- index notches.

A leaf-turning assembly 23 is mounted on the carriage 20. In the operative position, i.e. during turning of leaves, this assembly is set in a fixed position relative to the carriage. When inserting and removing bundles of sheets or catalogues, it may, however, be moved so as not to come into engagement with the bundle of sheets or catalogue during handling thereof. This leaf-turning assembly is not part of the present invention but may be a prior-art type of leaf-turning assembly. To ensure the correct leaf-turning result, it is, however, necessary for the sheet engaging parts of the leaf-turning assembly to be always held in the correct position relative to one corner of the outer sheet, not yet turned, in a hanging bundle of sheets.

In the carriage 20 there is holder 24 for a bundle of sheets 25. The holder grips a portion of the bundle of sheets close to the spine thereof (i.e. the edge portion opposite the edge portion which is to be formed with a thumb-index notch) . It should be emphasised in this context that the bundle of sheets need not necessarily be bound but can constitute a pile of loose sheets. The holder 24 is arranged to hold the spine in an essentially horizontal position and is vertically movable relative to the carriage 20 and, thus, relative to the leaf-turning assembly 23. For these purposes, the holder 24 has a bundle supporting surface 26 and a clamp- ing rib 27, between which the bundle of sheets 25 is clamped. The clamping rib 27 is movable towards and away from the bundle supporting surface 26 by means of pneuma- tic or hydraulic cylinders, the piston rods 28 of which are connected to the clamping rib 27.

The bundle of sheets 25 is always placed in the holder 24 in such a manner that the free sheet edge which is to be formed with thumb-index notches always projects to the same extent from the holder when the sheet extends horizontally outwards from the holder in the direction of the cutting assembly 11. In connection with bundles of broad sheets, the holder will therefore grip a broader edge portion, seen from the spine of the bundle of sheets, than in the case where bundles of narrower sheets are treated.

The holder 24 is in its entirety vertically adjustable relative to the rest of the carriage 20. To this end, use is made of a screw 60, which supports the holder and which is operated by a stepping motor 29 to move the holder along guide means 30. These are fixedly mounted in the carriage 20. The vertical indexing is carried out in steps which are of the same size as the thickness of the sheets in the bundle of sheets 25, such that the sheet which is the next to be turned always has its gripped edge portion on a level with the lower cutting blade 12. The part of the bundle of sheets 25, which projects from the holder, hangs down over a supporting rod 31. The ends thereof are rigidly attached to the outer end of link arms 32. The other end of these is pivotally attached to a plate 33, which is rigidly fixed to the carriage 20. Outside the link arm 32 there are two parallel arms 34, 35 which at one end are pivotally mounted on the plate 33 and, at the other end, are pivotally connected to a supporting plate 36. The supporting plate thus is retained in a vertical position independently of the extent at which the parallel arms 34, 35 are pivoted relative to the carriage 20. The lowermost sheet of the hanging bundle of sheets 25 rests against this plate 36. At a point (pivot pin 37) between its ends, the link arm 32 is pivotally connected to the upper parallel arm 34. As a result, the supporting rod 31 will be pivoted relative to the holder 24 concurrently with the parallel displacement of the supporting plate 36 towards and away from the holder 24. The movements of the parallel arms 34, 35 and, thus, the supporting plate 36 and the supporting rod 31 are determined by a cam and cam follower mechanism at each end of the carriage 20. This mechanism comprises a cam plate 38 which is rigidly fixed to the lower parallel arm 35, and a cam follower 39 which is rigidly fixed to a side member 40 of the holder 24 to follow the vertical movements of the holder when moving the bundle of sheets 25 in the vertical direction.

Since the cam 38 engages the cam follower 39 and the cam follower follows the side member 40 in the upward movement of the holder 24 when the holder is indexed upwards by means of the stepping motor 29, the cam and cam follower mechanism 38, 39 will make the supporting plate 36 and, thus, the hanging part of the bundle of sheets 25 move outwards from the sheet holder. At the same time the upper parallel arm 34 will make the link arm 32 pivot outwards, thereby pivoting the supporting rod 31 upwards and away from the holder 24.

The supporting rod 31 has, according to the inven- tion, been formed with a profiled surface, such that the surface of the supporting rod facing the bundle of sheets 25 has a supporting surface profile which is approximately parabolic with a radius of curvature that varies from a small radius of curvature to a large radius of curva- ture, the smallest radius of curvature corresponding to the radius of curvature of the lowermost sheet in the bundle of sheets when the supporting rod supports a bundle of sheets in which the sheets have not been turned, and the largest radius of curvature corresponding to the radius of curvature of the lowermost sheet in the bundle of sheets when at the same time this constitutes the only remaining sheet which is not turned. This is apparent from Figs 3-8. The part of the supporting rod which is at the top when the supporting rod is in its lower position (Fig. 5) has an essentially cylindrical circumferential surface portion 41 up to the dash-dot line 42. The cylindrical circumferential surface portion 41 then passes into a circumferential surface portion 43 with an increasing radius of curvature such that the surface portions of the rod engaging the lower surface of the hanging sheet of bundles obtain an approximately parabolic cross-sectional shape. With a view to permitting a uniform transition from the end of this approximately parabolic circumferential surface portion 43 to the planar vertical outer surface of the supporting plate 36, the outer end of the circumferential surface portion 43 has the form of arcuate fingers 45.

These fingers mesh into corresponding recesses 44 of the supporting plate. This arrangement results in the fingers 45 taking over the supporting function in the terminating phases of the upwardly pivoting movement of the support- ing rod (from Fig. 3 to Fig. 4).

As appears from Figs 5-8, this design of the circumferential surface 41, 43 of the supporting rod 31 corresponds to the "normal" curvature of the lowermost sheet of the sheets in a hanging bundle of sheets if the sheet which is positioned furthest to the right in the engagement area of the suction nozzle 46 of the leaf-turning assembly 23 in Figs 5-8 and which is just to be turned, is continuously held in the same form of curvature independently of where in the bundle of sheets the sheet con- cerned is positioned. By the supporting rod 31 being pivoted outwards and upwards concurrently with the leaf- turning operation and since the supporting surface 36 is moved in parallel in steps outwards according to the thickness of the individual turned sheets, the support- ing rod will, during the outwards movement, support the lowermost sheet in the bundle of sheets with a supporting surface portion having an increasing radius of curvature. In this way it is ensured that the distance A is always kept constant. The distance A is the distance between a vertical plane through the edge of the lower cutting blade 12 and the portion, hanging down straight, of the sheet which is closest to the leaf-turning nozzle 23 and which is therefore the next to be turned. By the holder 24 and, thus, the bundle of sheets 25 being indexed upwards concurrently with the turning of sheets, such that the clamped edge portion of the individual sheet subjected to turning is always on a level with the lower cutting blade 12, the distance B between the lower edge of this sheet and the cutting blade 12 will be kept constant during the leaf-turning operation. This implies in turn that the sheet which is subjected to turning always has the same position relative to the suction nozzle 46 of the leaf-turning assembly (shown in Fig. 7 only) .

With a view to ensuring that the bundle of sheets is hanging down correctly and is not resilient outwards (to the right in respect of Figs 5-8) owing to the rigidity of the individual sheet in the bundle of sheets (these can also have different rigidity if different types of sheet are used in the bundle of sheets or the document), the device is provided with a pressing beam 47. This beam is fixed to a pivot arm 48 which is mounted in the frame of the carriage 20 and the pivoting position of which is controlled by a piston-and-cylinder assembly 49, whose piston is pivotally connected to a pivot pin 50 of the pivot arm. The pivot arm is pivoted between two positions, an upper position just below the edge of the lower cutting blade 12 and a lower position where it abuts against the outermost sheet in the hanging part of the bundle of sheets 25. To ensure that the pressing beam is always correctly positioned when it has taken its lower position, use is made of a bracket 51 which is attached to the frame of the carriage 20 and against which the pressing beam rests when it has taken its lower position. The pressing beam is attached to the pivot arm 48 in a cantilevered manner and extends not quite up to the opposite edge of the bundle of sheets since the leaf-turning assembly 23 must have place and also the possibility of gripping, bending and turning a corner portion of the sheets. The path of motion of the pressing beam is indicated by dash-dot lines in Fig. 7.

This Figure also shows how the turned leaves are moved up to the cutting position on top of the lower cutting blade 12. In the turning operation, the corner portion of the individual sheet on a level with the leaf-turning assembly is sucked outwards by the suction nozzle 46, which is then moved a short distance away from the bundle of sheets to entrain the corner portion of the sheet held by suction while at the same time a wiping rod (not shown) is inserted between the rest of the bundle of sheets and the pulled-out corner portion of the sheet and pulls this corner portion outwards to make it rest against the outside of the suction nozzle while the subsequent sheet is turned and until an intended group of sheets has been fully turned.

When the required number of sheets has been turned, the pressing beam 47 is pivoted upwards to its upper position close to the lower cutting blade 12. The turned sheets will then pivot slightly outwards away from the rest of the bundle of sheets. Subsequently a lifting beam 52 is moved obliquely upwards between the lowermost of the turned sheets and the rest of the hanging bundle of sheets to lift the turned sheets. The lifting movement proceeds so far upwards that the group of turned sheets is bent and pulled past the pressing beam and forms an upward arc (see Fig. 7). Then the lifting beam 52 is lowered such that its upper edge is aligned with the edge of the lower cutting blade 12. In this way, the lifting beam will assist in holding the sheets essentially flat and correctly positioned relative to the lower cutting blade when the cutting operation is to be effected. Fig. 7 shows merely the upper and lower positions of the lifting beam 52 and its path of motion.

With a view to lifting the cut sheets and holding them in a raised position during the turning and the cutting of the next sheet, there are two paper handling beams 53, 54. Each beam is at one end fixedly connected with two guide means 55 which are passed through guide sleeves 56. These are in turn attached to a pivotable arm 57, which at its upper end is pivotally attached to an upwardly projecting part of the frame of the carriage 20. By means of a piston-and-cylinder assembly 58 each, the beams 53 can be raised and lowered. The arm 57 can also be pivoted towards and away from the turned and cut parts of the bundle of sheets. To this end, there is a further piston-and-cylinder assembly 59.

The two paper handling beams 53, 54 project in a cantilevered manner from the two guide means 55 and are directed towards each other, as is evident from Fig. 9.

The movement pattern of the two beams is as follows. One beam 53 is in its starting position adjacent to the lower cutting blade 12 (see Fig. 6) . Now the upper edge of the beam is aligned with the edge of the lower cutting blade to allow the beam to assist in holding the sheets straight and in the correct position when they are to be cut. At the same time the other beam 54 is in an upper position, in which it is pivoted towards and pressed against the already turned and cut sheets in the bundle of sheets. When a group of sheets has been cut and the lifting beam 52 (see Fig. 7) has been pulled downwards from its sheet-supporting position (not shown, but on a level with the edge of the lower cutting blade, as mentioned above) , the beam 53 is pivoted clockwise in respect of Fig. 6 so as to simultaneously move along the underside of the just cut sheets. When the beam has come as far to the left as possible and presses the just cut sheets against the rest of the cut bundle of sheets, the beam 53 is pulled upwards up to the position which the beam 54 takes. The sheets will thus be extended and laid in the correct position, in engagement with the already cut, upwardly directed sheets. Before the beam 53 has reached the beam 54, the latter is pivoted outwards, as shown in Fig. 6. The beam 54 is then moved straight down to the level of the edge of the lower cutting blade 12. Thus the beams 53 and 54 operate alternatingly such that one supports the sheets that are to be cut and then moves them upwards while the other one holds the cut sheets in their upwardly directed position.

When the cutting of a group of sheets has been carried out, the carriage 20 is indexed along the cutting assembly, such that the next thumb-index obtains the intended position and size. The above example concerns an index-cutting machine, in which the sheet-treating device consists of a cutting tool. The invention can, however, be used for all types of sheet handling equipment, where it is necessary to ensure that an individual sheet in a bundle of sheets is held in a correctly aligned position, for instance, when the sheets are to be provided with pagination or marking in a predetermined position. The inventive sheet-aligning device can also be used for other purposes, for instance for counting the number of notes or documents in a bundle of notes or documents while simultaneously checking the authenticity of the sheets or notes by sensing an identification mark by means of camera equipment or some other detecting equipment.

Claims

1. A sheet-aligning device for a leaf-turning device (23) with a subframe (20) included in a sheet-treating device, said sheet-aligning device comprising a holder (24) which is intended for a bundle of sheets (25) and which is adapted to grip the bundle of sheets along an edge area thereof to hold the edge area, grip- ped by the holder, of the bundle of sheets in an essentially horizontal position, a supporting rod (31), which serves to support a portion of the bundle of sheets outside said edge area and outside which the sheets are hanging down, and a moving mechanism (29, 30, 32-39) for moving the holder (24) and the supporting rod (31) relative to each other and relative to the frame of sheet-treating device for retaining the free outer edge of the uppermost sheet in the bundle of sheets in a predetermined position relative to the subframe (20) and the leaf-turning device (23) , c h a r a c t e r i s e d in that the supporting rod (31), seen in cross-section, has an approximately parabolic supporting surface (41, 43) engaging the bundle of sheets (25) , that the moving mechanism (29, 30, 32-39) comprises sheet bundle lifting means (29, 30) , which are adapted to successively raise the bundle of sheets (25) upwards in the subframe (20) , such that the underside of a just turned leaf is in a predetermined vertical position relative to the subframe, and supporting rod operating means (32-39) which are adapted to pivot the supporting rod (31) while moving relative to the subframe (20) and the leaf-turning device (23) , such that the supporting surface (41, 43) of the sup- porting rod engages the lowermost sheet in the bundle of sheets with curved surface portions having an increasing radius of curvature the thinner the bundle of sheets during turning of the leaves and such that each sheet which is the next to be turned is held in essentially the same curved shape.

2. A device as claimed in claim 1, c h a r a c t e r i s e d in that the moving mechanism (29, 30, 32-39) also comprises a sheet supporting surface (36) which is connected to the subframe (20) by means of two parallel arms (34, 35), which at one end are pivotally fixed to the subframe (20) and at the other end are pivotally connected to the sheet-supporting surface (36) for moving this in parallel in pivoting the parallel arms (34, 35), a driving device (38, 39) for pivoting the parallel arms (34, 35) and moving the sheet supporting surface (36) upwards according to the thickness of the turned sheet, such that each sheet which is the next to be turned is always in an essentially fixed plane relative to the subframe (20) , and a pivot arm (32) which at one end is connected to the supporting rod (31) and at the other end is pivotally attached to the subframe (20) and which is connected to a driving source (34, 37) for pivoting the pivot arm (32) and, thus, the supporting surface (41, 43) of the supporting rod (31) concurrently with the parallel arms (34, 35) .

3. A device as claimed in claim 2, c h a r a c t e r i s e d in that the pivot arm (32) is at one point (37) between its ends pivotally and operatively connected to one (34) of the parallel arms (34, 35) to be pivoted concurrently therewith.

4. A device as claimed in claim 3, c h a r a c t e r i s e d in that the sheet bundle lifting means (29, 30) are, via a cam and cam follower assembly (38, 39) , operatively connected to the supporting rod operating means (32-39) to make, when raising and lowering the holder (24) relative to the subframe (20), the supporting rod operating means (32-39) move the sheet support- ing surface (36) in parallel and effect a pivoting of the pivot arm (32) and, thus, the supporting rod (31).

5. A sheet-treating device, which has a leaf-turning device (23), a sheet-treating means (11) and a sheet- aligning device for aligning individual sheets included in a bundle of sheets in the correct position relative to the sheet-treating means, the leaf-treating means (11) being arranged in a frame (10) and the sheet turning device (23) being arranged in a subframe (20) which is movable relative to the frame, said sheet-treating device comprising a holder (24) which is intended for a bundle of sheets (25) and which is adapted to grip the bundle of sheets along an edge area thereof to hold the edge area, gripped by the holder, of the bundle of sheets in an essen- tially horizontal position, a supporting rod (31) , which serves to support a portion of the bundle of sheets outside said edge area and outside which the sheets are hanging down, and a moving mechanism (29, 30, 32-39) for moving the holder (24) and the supporting rod (31) relative to each other and relative to the subframe (20) for retaining the free outer edge of the upper sheet in the bundle of sheets in a predetermined position relative to the subframe (20) and the leaf-turning device (23) , c h a r a c t e r i s e d in that the supporting rod (31), seen in cross-section, has an approximately parabolic supporting surface (41, 43) engaging the bundle of sheets (25), that the moving mechanism (29, 30, 32-39) comprises sheet bundle lifting means (29, 30) , which are adapted to successively raise the bundle of sheets (25) upwards in the subframe (20), such that the underside of a just turned leaf is in a predetermined vertical position relative to the subframe, supporting rod operating means (32-39), which are adapted to pivot the supporting rod (31) while moving relative to the subframe (20) and the leaf-turning device (23) , such that the supporting surface (41, 43) of the supporting rod engages the lowermost sheet in the bundle of sheets with curved surface portions having an increasing radius of curvature the thinner the bundle of sheets during the turning of the sheets, and such that each sheet which is the next to be turned is held in essentially the same curved shape.

6. A device as claimed in claim 5, c h a r a c t e r i s e d in that the moving mechanism (29, 30, 32-39) also comprises a sheet supporting surface (36) which is connected to the subframe (20) by means of two parallel arms (34, 45), which at one end are pivotally fixed to the subframe (20) and at the other end are pivotally connected to the sheet supporting surface (36) for moving this in parallel in pivoting the parallel arms (34, 35), a driving device (38, 39) for pivoting the parallel arms (34, 35) and moving the sheet supporting surface (36) upwards according to the thickness of the sheet turned, such that each sheet which is the next to be turned is always in an essentially fixed plane relative to the subframe (20) , and a pivot arm (32) which at one end is connected to the supporting rod (31) and at the other end is pivotally attached to the subframe (20) and which is connected to a driving source (34, 37) for pivoting the pivot arm (32) and, thus, the supporting surface (41, 43) of the supporting rod (31) concurrently with the parallel arms (34, 35).

7. A device as claimed in claim 6, c h a r a c t e r i s e d in that the pivot arm (32) is at one point (37) between its ends pivotally and operatively connected to one (34) of the parallel arms (34, 35) to be pivoted concurrently therewith.

8. A device as claimed in claim 7, c h a r a c t e r i s e d in that the sheet bundle lifting means (29, 30) are, via a cam and cam follower assembly (38, 39) , operatively connected to the supporting rod operat- ing means (32-39) to make, when raising and lowering the holder (24) relative to the subframe (20), the supporting rod operating means (32-39) move the sheet supporting surface (36) in parallel and effect a pivoting of the pivot arm (32) and, thus, the supporting rod (31) .