EP3482966A1 - Method and device for sewing - Google Patents

Abstract

The invention relates to a method and a device for thread stitching folded printed sheets (5), in which individual folded printed sheets (5) successively strung together flat and with at least one sewing needle (13) and at least one hook needle (14) to a book block (6). sewn. In this case, the hook needle (14) is previously turned from the inside to the outside penetrating the fold (10) of the sheet to be sewn (5) and the eyelet (22) of the previously sewn print sheet (5) about its longitudinal axis (27) that its Hook (15) in a vertical plane of symmetry (33) of this eyelet (22) and on a side of the previously stitched sheet (5) facing side of the hook needle (14) is positioned. For this purpose, the hook needle (14) is rotatable about its longitudinal axis (27) in an arbitrary angle of rotation (±) and the hook (15) can be positioned in any desired rotational position.

Description

The invention relates to a method and an apparatus for thread stitching folded printed sheets, in which individual folded printed sheets successively strung flat against each other and sewn with at least one sewing needle and at least one hook needle to a book block.

For this purpose, the at least one sewing needle brings a binding thread from the outside through the fold of a printed sheet to be sewn inwards, between its legs, thereby producing on an outer side of the fold a first, single-stranded seam. Then, the binding thread between the legs of the folded sheet is stored and transported so far from the sewing needle in the form of a thread loop in the direction of a movement path of the hook needle that extends a closed end of the thread loop beyond this movement path. Thereafter, the at least one hooked needle emerges through an eyelet of the same binding thread formed on the outside of the fold when sewing the previous printed sheet and through the fold of the printed sheet to be sewn in, between its legs into the previously formed thread loop, grasping it during a return stroke and conveys them from the inside through the fold of the printed sheet to be sewn and through the eyelet located on the outside of the fold. In this case, a second, double-stranded seam spaced from the first, single-stranded seam is produced on the outside of the fold. The one hook for forming the binding thread forming hook, one-sided recess having hook needle is rotated for sewing the sheet around its longitudinal axis and their hooks thereby positioned in different rotational positions.

From the CH24452 and the CH55948 are thread stitching machines with Vorstechnadeln, each pairwise cooperating, up and down movable sewing needles and hook needles and each one between a sewing needle and a hook needle back and forth movable thread layer known. During operation of such thread stitching machines, a plurality of loose, upright and with their broad side in stack form juxtaposed, folded printed sheet are individually connected to at least two of the same binding thread seams to book block. For this purpose, each of the successively provided sheet is first pierced by means of two spaced apart from each other and between its two legs, that is brought from an inner side of the fold forth Vorstechnadeln at its fold. After retraction of the Vorstechnadeln from the outside of the fold forth through the first of the two holes formed by the Vorstechnadeln a Nadelöhr having needle and through the second hole equipped with a one-sided, upwardly open hook hook needle out. In this case, a suture needle located in the needle eye, for example, supplied by a bobbin and possibly already sewn with the previous sheet binder between the legs of the sheet introduced and created in this interior of the sheet to be sewn a thread supply. As a result, a first, single-stranded seam is formed on the outside of the fold, or such a seam, which has already formed on the outside of the fold of at least one pre-stitched (synonymously stitched) printed sheet, is continued.

The now stored within the stapled (synonymous: to be sewn) sheet binder thread is transported by the thread layer in the form of a loop in the direction of the hook needle and there positioned their trajectory across. During its downward movement, the hook needle dives through the loop of the binding thread provided by the thread feeder. Thereafter, this thread loop is pulled taut around the hook needle and detected in the subsequent upward movement by means of the hook. The thread loop is then pulled upwards, through the second hole of the fold of the sheet to be stapled and through a loop surrounding the hook needle, formed from the thread loop of the previously stitched sheet. In this way, a second, double-stranded seam is formed on the outside of the fold, or such a seam formed on the outside of the fold of at least one pre-stitched press sheet is continued. With the immersion of the sewing needle and the hook needle in the two holes of the next provided for thread stitching sheet begins the process described above again, which can be repeated several times depending on the book block to be produced.

When sewing a double rotation of the hook needle of 180 ° about its longitudinal axis, for which purpose designed control cams or cams are used. At the beginning of the downward movement, the hook needle is rotated in such a way that the hook is subsequently on its side remote from the already stitched sheet. This prevents unhooking of the eyelet formed from the thread loop of the previously stitched sheet. At the latest during the upward movement of the hook needle, ie on the Rückhubweg, a second rotation takes place such that the hook is on its already stapled printed sheet facing side. This ensures that the currently formed loop of the binding thread is caught by the hook and passed through the eyelet of the previously stitched sheet, without taking the latter.

The EP832758 A2 discloses a similar method for producing thread-stitched book blocks from a stack of flat-lined signature, but in which instead of a mechanical thread leveler, a gas stream is used to transport the loop-shaped binding thread from the sewing needle to the hook needle. The downward movement of the hook needle with respect to the downward movement of the sewing needle is offset in time, ie later. Also in this solution, the hook needle for the downward movement and the upward movement is rotated in each case by 180 °. This is done by means of a hydraulic cylinder, which also like in the CH24452 used cams or as the cams according to the CH55948 exactly two angles of rotation of 180 °, ie two corresponding rotational positions of the hook of the hook needle permits. As a control element for transmitting power from the drive to the hook hook to be rotated in each case a rack is used in the said solutions of the prior art.

Such, always same rotation of the hook needle 180 ° is easy to implement and proves to be advantageous if the book blocks always from the same thickness Sheet be formed. As soon as successive book blocks have different thicknesses printed sheets, but especially when using thin sheets, there is a risk that the hook of the hook needle violates the eyelet formed from the thread loop of the previously stitched sheet, ie splits, tears or even severed. This undesirable effect can be further enhanced due to manufacturing tolerances of the hook needle, in particular already by a slightly different rotational position of the hook.

If sheets of thin material are to be used for the production of relatively thick book blocks, this has the disadvantage that the binder thread is applied in an undesired manner. In thread stitching, therefore, in such a case, instead of the normal stitch in which the loop of the binding thread is always formed in the same direction from the sewing needle, the change stitch is frequently used in which the thread loop is formed alternately to the right or to the left. In such a solution, however, the risk of injury to the eyelet formed from the thread loop of the previously stitched sheet still increases because it has a smaller distance to the hook of the hook needle with thin signature than with thick signature. In addition to the nature of the stitches and thus the different direction of the loop formation, to avoid injury to the eyelets of previously stapled printed sheet and the different separation of successive book block or corrections in thread stitching errors incurred are observed.

It was therefore an object of the invention to provide a method and apparatus for thread stitching folded sheets, which increases the quality of the book block to be produced and in particular reduces the risk of injury each formed from the thread loop of a pre-stitched sheet loop even when using thin sheets can be.

This object is achieved by a method according to which the hook needle in front of the taking place from the inside out penetrating the fold of the sheet to be sewn and the eyelet of the previously sewn signature so in their The longitudinal axis is rotated so that its hook is positioned in a vertical plane of symmetry of this eyelet and on a side of the hook needle facing the previously sewn press sheet. With this method, the hook of the hook needle can be positioned as far as possible away from this eyelet in advance of the penetration from inside out of the loop formed from the thread loop of the previously sewn press sheet. Therefore, the risk of damaging the eyelet can be minimized. In addition, it is ensured that the eyelet is not picked up again by the hook of the hook needle. In this way, the quality of the book block over such book block produced by the prior art can be increased.

According to an advantageous embodiment of the method, the at least one hooked needle is rotated about its longitudinal axis before the detection of the thread loop such that the hook of this hooked needle is positioned on its side opposite the sewing needle. By this rotation of the hook needle and the corresponding positioning of the hook, the thread loop can be reliably detected during the return stroke of the hook needle with the hook. Thus, a high quality of the book block to be produced can be ensured.

According to a further advantageous embodiment of the method, the at least one hooked needle is rotated about its longitudinal axis before the detection of the thread loop that its hook then at an angle of +/- 85 °, preferably at an angle of +/- 50 ° and particularly preferred is positioned at an angle of +/- 15 ° with respect to a first vertical plane through the fold of the sheet to be stapled. This advantageous ranges for the rotation of the hook needle or for the positioning of the hook are indicated.

According to a next advantageous embodiment of the method, the at least one hooked needle is rotated about its longitudinal axis in front of the penetrating from outside to inside the eyelet of the previous sheet and the fold of the sheet to be sewn, that their hooks in a second vertical and at right angles to the fold of aligned to sewn press sheet, imaginary plane, is positioned on a side facing away from the previously sewn printed sheet side of the hook needle in a start rotational position. With this position, a rotation of the hook needle and a positioning of the hook is defined in a first rotational position, which can then be advantageously used as a starting rotational position for the further rotation of the hook needle or for the further positioning of the hook. In addition, the three available and individually adjustable rotational positions better than the two known from the prior art fixed rotational positions on the three critical process steps of Fadenheftens, namely from outside to inside insertion of the hook needles through the fold of the sheet to be sewn, the detection of the thread loops with the hooks of the hook needles and the inward outward penetration of the hooks of the hook needles are divided by the respectively located on the outside of the fold eyelet of the previous sheet.

According to a further advantageous embodiment of the method, for each stitch to be sewn, based on in a machine control of a device for thread stitching or deposited on at least one of the sheets to be stitched information on the nature of the stitching of the printed sheets of a production order to be taken stitches and for the separation of the produced Book block, starting from the start rotational position of the hook of the at least one hook needle, corresponding rotation angle of at least one hook needle determined about its longitudinal axis, the at least one hook needle is rotated according to the determined rotation angle and their hooks positioned accordingly. In this case, the information applied to at least one of the printed sheets to be sewn may be, for example, an identification by means of a barcode, an RFID transponder or a print mark. In this way, it is possible to react advantageously both to the paper thickness and to further paper properties as well as to the thread thickness and to further thread properties.

According to a next advantageous embodiment of the method, the rotation of the at least one hook needle about the determined angle of rotation and the corresponding positioning of the hook with a drive, in particular with a Servomotor. With such a drive and in particular with a servo motor, in principle any rotation of the hook needle and thus any positioning of the hook can be realized very accurately and quickly. As a result, the hook needle can be rotated during each sub-process of thread stapling so that its hook is optimally positioned.

The object is also achieved by a device in which the hook needle is rotatable about its longitudinal axis in any rotational angle and the hook is positionable in any desired rotational position. With such a device, the hook of the hook needle can always optimally positioned and thereby the quality of the book block to be produced can be increased. In particular, the risk of injury to each formed from the thread loop of a previously stitched sheet can be reduced even when using thin sheets.

According to an advantageous embodiment, this device has a device operatively connected to a machine control for rotating the at least one hook needle about its longitudinal axis, wherein the device comprises a holder for the at least one hook needle, an actuating element for rotating the at least one hook needle and a drive for the actuating element. When using such a device can be rotated by means of a single drive advantageously a large number of hook needles.

According to a further embodiment of the device, the drive has a servomotor. With such a servo motor can advantageously be realized every rotation of the hook needle and thus each positioning of the hook.

According to a next embodiment of the device, the actuator is equipped with a rack. Such a rack is a simple, inexpensive and proven in such applications component for transmitting the torque from the drive to the hook needles.

Fig. 1 - 4

eine schematische Darstellung des aus dem Stand der Technik bekannten Nähprinzips einer im Normalstich arbeitenden Vorrichtung,

Fig. 5

eine schematische Draufsicht auf die Näh- und Hakennadel der Vorrichtung gemäß Fig. 1, mit den beiden Drehpositionen der Hakennadel bzw. ihres Hakens,

Fig. 6

eine schematische Seitenansicht der Näh- und Hakennadeln einer für den Wechselstich vorgesehenen Vorrichtung zum Fadenheften des Standes der Technik, mit einer darunter abgebildeten schematischen Draufsicht auf fünf mit dieser Vorrichtung vernähte Druckbogen,

Fig. 7

eine schematische Schnittdarstellung der Hakennadel einer erfindungsgemäßen Vorrichtung zum Fadenheften, welche die Hakennadel mit ihrem Haken in einer erfindungsgemäßen Drehposition beim Durchdringen einer nach rechts ausgerichteten Öse eines vorherigen Druckbogens sowie eine links von der Hakennadel angeordnete Nähnadel zeigt,

Fig. 8

eine Darstellung der gleichen Hakennadel wie in Fig. 7, welche jedoch in einer anderen erfindungsgemäßen Drehposition beim Durchdringen einer nach links ausgerichteten Öse eines vorherigen Druckbogens sowie mit einer rechts von der Hakennadel angeordneten Nähnadel gezeigt ist,

Fig. 9

eine schematische Draufsicht auf die Näh- und Hakennadel einer erfindungsgemäßen Vorrichtung zum Fadenheften, mit weiteren erfindungsgemäßen Drehpositionen der Hakennadel und ihres Hakens zum Erfassen einer von links zugeführten Fadenschlaufe,

Fig. 10

eine schematische Darstellung analog Fig. 9, jedoch mit weiteren erfindungsgemäßen Drehpositionen der Hakennadel und ihres Hakens zum Erfassen einer von rechts zugeführten Fadenschlaufe, und

Fig. 11

eine schematische Darstellung einer Einrichtung zum Drehen von Hakennadeln einer erfindungsgemäßen Vorrichtung zum Fadenheften.

The invention will be described in more detail with reference to an embodiment. Showing:

Fig. 1 - 4th

1 is a schematic representation of the sewing principle known from the prior art of a normally stitching device;

Fig. 5

a schematic plan view of the sewing and hook needle of the device according to Fig. 1 , with the two rotational positions of the hook needle or its hook,

Fig. 6

3 is a schematic side view of the sewing and hook needles of an apparatus for thread stitching of the prior art provided for the interchangeable stitch, with a schematic plan view, shown below, of five printed sheets sewn to this apparatus;

Fig. 7

a schematic sectional view of the hook needle of a device according to the invention for thread stitching, which shows the hook needle with its hook in a rotational position according to the invention when penetrating a right-aligned eyelet of a previous sheet and a left of the hook needle arranged sewing needle,

Fig. 8

a representation of the same hook needle as in Fig. 7 which, however, is shown in another rotational position according to the invention when penetrating a leftward eyelet of a preceding printing sheet and with a sewing needle arranged to the right of the hook needle,

Fig. 9

a schematic plan view of the needle and hook needle of a device according to the invention for thread stitching, with further inventive rotational positions of the hook needle and its hook for detecting a supplied from the left thread loop,

Fig. 10

a schematic representation analog Fig. 9 , but with further inventive rotary positions of the hook needle and its hook for detecting a fed from the right thread loop, and

Fig. 11

a schematic representation of a device for rotating hook needles of a device according to the invention for thread stitching.

Fig. 1 to 4 show a schematic representation of the known from the prior art sewing principle of an intended for normal stitch device 1 for stitching. In Fig. 1 is a book block 6 formed from two folded, flat juxtaposed and already by means of a binding thread 2 in the form of two spaced seams 3, 4 stitched together sheet 5 formed. For this purpose, each conveyed one after the other in a feed direction 7 to a saddle not shown, folded printed sheet 5 each have a first leg 8 and a second leg 9 and a fold 10 connecting them.

Also shown is a third, folded printed sheet 5, which is transported in the feed direction 7 to the book block 6, with its first leg 8 flatly applied to the book block 6 and thus provided for sewing with this book block 6. For a better understanding of the sewing principle of this further, not shown on the stitch saddle resting sheet 5 is shown cut through at its fold 10, that is, it is only the first leg 8 of the third sheet 5 shown, while its second leg 9 has been omitted. In addition, two spaced apart Vorstechnadeln 11, a Nadelöhr 12 having sewing needle 13, a spaced in the direction of the fold 10 of the third folded sheet 5 from the sewing needle 13 hook needle 14 with a located at the periphery, a hook 15 forming recess 16 (FIG. see also Fig. 7, Fig. 8 ) and on the side remote from the hook needle 14 side of the sewing needle 13 and formed as a transport element for the binding yarn 2 Blasluftdüse 17 and a link 18 of the device 1 shown.

During operation of the device 1, the two preforming needles 11 first pierce the fold 10 of the printed sheet 5 to be sewn from the inside in the direction of the illustrated movement arrows, forming two spaced-apart holes 19 in this fold 10 (FIG. Fig. 1 ). After the Vorstechnadeln 11 have been withdrawn against the movement arrows, the first positioned on an outer side 20 of the fold 10, for example, provided by a bobbin, not shown, binding yarn 2 in her Nadelöhr 12 leading sewing needle 13th introduced through a first of the two holes 19 in an inner space 21 located between the two legs 8, 9 of the pressure sheet 5 to be sewn. In this case, a first portion 2a of the binding thread 2 located on a first side of the needle eye 12 is connected to a first, single-stranded seam 3 of the book block 6 formed on the outer side 20 of the fold 10, while a second portion 2b located on a second side of the needle eye 12 of the binding thread 2 is connected to the thread bobbin, not shown. At this time, the hook needle 14 is still on the outside 20 of the fold 10 of the sheet to be sewn 5 and there is surrounded by a loop formed from a thread loop of the binding thread used for sewing the previous sheet 5 5 eyelet 22 ( Fig. 2 ).

The two sections 2 a, 2 b of the binding thread 2 are then acted upon by means of an air blast 23 occurring through the blast air nozzle 17 and transported in the direction of a movement path 24 of the hook needle 14 shown in dashed lines. In this case, a thread loop 25 forms with a closed end 26 ( Fig. 3 ). This thread loop 25 is guided into the slot 18 and thereby positioned so that its closed end 26 finally extends beyond the path of movement 24 of the hook needle 14, to which the sewing needle 13 side facing away from this movement path 24. Of course, instead of a blower 17 designed as a pneumatic transport element for the binding yarn 2, a known per se, designed as a thread-laying, mechanical transport element can be used.

Thereafter, the hooked needle 14 surrounded on the outer side 20 of the fold 10 by the eyelet 22 emerges from the outside through the second, formed by the Vorstechnadeln 11 hole 19 in the located between the legs 8, 9 interior 21 of the printed sheet to be sewn 5 and enters finally through the thread loop 25 therethrough. On the return stroke of the hook needle 14 which meanwhile tightened to the latter thread loop 25 is detected by the hook 15 of the hook needle 14 and passed through the second hole 19 of the fold 10 and located on the outside 20 eyelet 22. In this case, a second, double-stranded seam 4 is formed on this outer side 20 of the fold 10, which in the direction of this Fold 10 is spaced from the first, single-stranded seam 3 ( Fig. 4 ). After providing a next, to be sewn press sheet 5 of the above-described process of Fadenheftens starts again.

Fig. 5 shows a schematic plan view of a sewing needle 13 with the always aligned Nadelöhr 12 and a cooperating with the sewing needle 13 hook needle 14. Shown here are in particular the two known from the prior art rotational positions of the hook needle 14 and its hook 15 with respect to Both during the movement of the hook needle 14 from the outer side 20 of the fold 10 into the interior 21 of the sheet to be sewn 5 and during their return stroke, the hook needle 14 is rotated 180 ° about its longitudinal axis 27 , It is irrelevant whether the rotation is in or counterclockwise. As this is illustrated by way of example with reference to a first and a second movement arrow 28, 29, the hook needle 14 and hook 15 accordingly have a first rotational position 30 and a second rotational position 31, respectively. In its first rotational position 30, the hook 15 is in a second vertical and at right angles to the fold 10 of the sheet to be sewn 5 aligned imaginary plane 32 and there on a side facing away from the previously sewn printed sheet 5 side of the hook needle 14. This is also in Fig. 3 shown. Before her on the return stroke passage through the fold 10 of the sheet to be sewn 5 and through the eyelet 22 of the previously sewn press sheet 5, the hook needle 14 and thus its hook 15 is rotated, for example, according to the second movement arrow 29 in the second rotational position 31. The hook 15 is then also in the second vertical plane 32, but on a pre-sewn press sheet 5 facing side of the hook needle 14. This position of the hook 15 can also Fig. 4 are removed, wherein the hook needle 14 there, however, already after the penetration of the fold 10 and the eyelet 22 is shown.

To rotate the hook needle 14, a suitably trained, not shown hydraulic cylinder is used, the first end position of the first rotational position 30 of the hook needle 14 and its hook 15 and the second end position of the second rotational position 31 of the hook needle 14 and its hook 15 corresponds. In the movement of the hook needle 14 from outside to inside, these and thus their hook 15 is in its first rotational position 30. This rotational position 30 of the hook 15 on the side of the hook needle 14 remote from the already stitched sheet 5 is observed at least as long as the hook 15 is still partially on the outside 20 of the fold 10 (see. Fig. 2, Fig. 3 ). This prevents too early unhooking of the eyelet 22 formed from the thread loop of the previously sewn printed sheet 5 out of the hook 15. After penetrating the seam 10, but at the latest before the hook 15 reaches the thread loop 25 in the case of the inside outward movement of the hook needle 14, the hook needle 14, however, is rotated so that its hook 15 in its second rotational position 31, ie on the the previously sewn press sheet 5 facing side of the hook needle 14 is (see. Fig. 5 above). This ensures that the currently formed thread loop 25 of the binding thread 2 is detected by the hook 14 and guided through the fold 10 of the sheet to be sewn 5 and through the eyelet 22 of the previously sewn print sheet 5, without taking the latter (see. Fig. 4 ). The next 180 ° rotation of the hook needle 14 and thus its hook 15, for example in the direction of the first movement arrow 28, takes place before their renewed movement from the outside inwards, ie before sewing a following signature 5. For the rotation of the hook needle 14 can according to the The prior art also find a control cam or a cam disc use.

Depending on the design of the book block 6 to be produced, further printed sheets 5 can be added in the same way. Although in the Fig. 1-5 each only a single sewing needle 13 and a single hook needle 14 are shown, depending on the length of the fold 10 of the sheet to be sewn 5 and of the respectively provided type of stitches produced with the sewing and hook needles 13, 14 - of course, a larger number of such needles are used.

Deviating from the in the Fig. 1-5 illustrated normal stitch, in which the binding yarn 2 is always transported starting from a spaced on the same side of the hook needle 14 sewing needle 13 to the hook needle 14, a device 1 for thread stitching folded sheet 5 course, be provided for the exchange stitch or be converted to this. In order to be able to realize this type of stitches, the respective hook needle 14 is arranged on both sides and a sewing needle 13 at the same distance therefrom, the supply of the binding thread 2 in the form of the thread loop 25 alternating with the hook needle 14 alternately from the one and the other sewing needle 13 is carried out starting. In Fig. 6 For example, three sewing needles 13 and two hook needles 14 of such an interchangeable apparatus 1 of the prior art are shown above, while in FIG Fig. 6 Below is a schematic plan view of five so each sewn at its fold 10 in the inter-stitch to a book block 6 printed sheet 5 is shown. It can clearly be seen that the eyelets 22 of the second, double-stranded seam 4, depending on which sewing needle 13 and thus from which side of the binding thread 2 has been guided to the hook needle 14, are aligned differently.

Those known from the prior art and in Fig. 5 shown second rotational position 31 of the hook needle 14 and its hook 15 when penetrating the seam 10 and in particular the eyelets 22 of each previously sewn print sheet 5 proves to be disadvantageous because on the one hand the orientation of the eyelets 22 so located of the second rotational position 31 in this Hook 15 of the hook needle 14 deviates that the binding thread 2 of the eyelets 22 can be injured by the hook 15 and because on the other hand, the orientation of the eyelets 22 according to the nature of the stitches (s. Fig. 2 and Fig. 6 ), which can increase the risk of tearing the binding thread 2 even more.

Fig. 7 shows a schematic representation of a section through a hook needle 14 and a cooperating with the hook needle 14, left of this arranged sewing needle 13 of a device 1 according to the invention for sewing thread. The also shown thread loop 25 of the binding thread 2 has thus been formed from left to right. This figure shows the hook needle 14 and the hook 15th each in a rotational position according to the invention when penetrating the not shown on the fold 10 of the currently sewn print sheet 5 and here shown in dashed lines eyelet 22 of the binding thread 2 of the previously sewn signature 5. For this purpose, the hook needle 14 has been rotated about its longitudinal axis 27, in that its hook 15 is arranged in a vertical plane of symmetry 33 of this eyelet 22 and positioned on a side of the hooked needle 14 facing the previously sewn printed sheet 5.

In Fig. 8 shows a schematic representation of a section through the same hook needle 14 as in Fig. 7 , but with another, arranged to the right of the hook needle 14, with this cooperating sewing needle 13. The thread loop 25 of the binding thread 2, also shown, has thus been formed from right to left. This figure shows the hook needle 14 and the hook 15 each in another rotational position according to the invention when penetrating the not shown on the fold 10 of the currently sewn print sheet 5 resting eyelet 22 of the binding thread 2 of the previously sewn print sheet 5. For this, the hook needle 14 is so rotated about its longitudinal axis 27, that its hook 15 in a vertical plane of symmetry 33 of this opposite Fig. 7 arranged differently eyelet 22 and is positioned on a side of the hook needle 14 facing the previously sewn press sheet 5.

This is in Fig. 7 and in Fig. 8 two different inventive rotational positions of the hook needle 14 and its hook 15 shown, which are dependent on which alignment has the resting on the fold 10 of the currently sewn print sheet 5 eyelet 22 of the binding thread 2 of the previously sewn print sheet 5. In addition to the type of stitches used in the sewing of the respective printing sheet 5, that is, for example, normal or alternating stitches, among other things, the separation of a currently sewn print sheet 5 from last stitched sheet 5 of a previous book block 6 and the type of used Material for the printing sheet 5 and the binding yarn 2 an influence on the orientation of the eyelet 22 of the previous sheet 5 and thus on the actual to assume the rotational position of the hook needle 14 or its hook 15 to be taken when penetrating from the inside to the outside of the eyelet 22 of the binding thread 2 of the previously sewn printed sheet fifth

Regarding also known from the prior art and in Fig. 5 shown first rotational position 30 of the hook needle 14 and its hook 15, it has been shown that this is not optimally aligned for detecting the thread loop 25. In contrast, ask FIGS. 9 and 10 in each case a schematic plan view of the sewing needle 13 and the hook needle 14 of a device 1 according to the invention for thread stitching, with further inventive rotary positions of the hook needle 14 and its hook 15 for detecting a from the left ( Fig. 9 ) or one from the right ( Fig. 10 Accordingly, the hook needle 14 is rotated before detecting the thread loop 25 about its longitudinal axis 27, that the hook 15 of the hook needle 14 is positioned on its side opposite the sewing needle 13 side. The hook 15 is thereby at an angle of +/- 85 °, preferably at an angle of +/- 50 ° and more preferably at an angle of +/- 15 ° relative to a first vertical plane 34 through the fold 10 of the stapling Sheet 5 turned. With such a rotational position of the hook needle 14 and its hook 15, the detection of the thread loop 25 can be improved by this hook 15 with respect to the prior art. In this case, the achievable rotational position of the hook needle 14 and its hook 15 is a compromise between the milliseconds measured, for turning the hook needle 14 available time and the optimal detection of the thread loop 25 through the hook 15th

Fig. 11 shows a schematic representation of a connected to a machine controller 35 means 36 for rotating the hook needles 14 of a device 1 according to the invention for stitching thread. Shown here is an example of a device 1 with four hook needles 14, wherein the sewing needles 13 cooperating with the hook needles 14 have been omitted for reasons of clarity. The device 36 for rotating the hook needles 14 has a holder 37 for rotatably receiving the hook needles 14, a rack 38 exhibiting Actuator 39 for rotating the hook needles 14 about its longitudinal axis 27 and a servo motor 40 having drive 41 for corresponding actuation of the actuating element 39. The hook needles 14 and thus their respective hooks 15 are thus in principle rotatable about its longitudinal axis 27 in an arbitrary rotational angle and can be stopped in any rotational position.

In the operation of this device 1, the hook needles 14 are for sewing a not shown stitch saddle supplied sheet 5 first each in an initial rotational position, which is known from the prior art and in the Fig. 1 to 3 and 5 shown first rotational position 30 corresponds. In other words, the hooks 15 are each in the second vertical and perpendicular to the fold 10 of the sheet to be sewn 5 aligned plane 32 and there on the side of the previously sewn sheet 5 side facing away from her hook needle 14, as shown schematically in FIG Fig. 6 above and Fig. 11 is shown.

After training and positioning of the respective thread loop 25 in the interior 21 of the sheet to be sewn 5 and after immersion of the hook needles 14 in this interior 21, as well as for a single hook needle 14 of the prior art already above the Fig. 1 to 4 is described, which are rotatably located in the holder 37 hook needles 14 and thus their hooks 15 from its initial rotational position after appropriate action by the drive 41 and the actuator 39, according to the invention either in one of Fig. 9 or in one of the in Fig. 10 rotated shown second rotational positions. This happens depending on whether the thread loop 25 is fed from a sewing needle 13 located on the left or on the right of the respective hook needle 14. During their return stroke, the hooks 15 of the hook needles 14 thus positioned engage the respective thread loop 25 and guide them out through the second hole 19 of the fold 10 of the printed sheet 5 to be sewn.

At the latest before the hooks 15 of the hook needles 14 in each case by the located on the outer side 20 of this fold 10 eyelet 22 of the binding thread 2 of the previously sewn Sheet 5 are moved, these hook needles 14 and thus their hooks 15 by means of the drive 41, for example, in a in the Fig. 7 or 8 shown rotated third rotational position. Because the hooks 15 are in this third rotational position on a previously sewn printed sheet 5 facing side of the hook needles 14 and in the plane of symmetry 33 of the respective eyelet 22 and thus relatively far away from the binding yarn 2, it is ensured that these eyelets 22 through the they each piercing hook 15 are not injured. Subsequently, but at the latest before the sewing stitching of the hook needles 14 from the outer side 20 of the fold 10 of this sheet 5 into the interior 21 of the sheet 20, the hook needles 14 and thus their hooks 15 are again in the initial rotational position already described above turned.

With this method and the corresponding device 1, a further rotational position of the hook needles 14 and of their respective hook 15 is added - in comparison with the known prior art with two fixed rotational positions offset by 180 ° in each case. The three now available rotational positions can better on the three critical process steps of Fadenheftens, namely the outside inward insertion of the hook needles 14 through the fold 10 of the sheet to be sewn 5, the detection of the thread loops with the hooks 15 of the hook needles 14 and the penetration of the hooks 15 of the hook needles 14, which takes place from the inside to the outside, is divided by the eyelet 22 of the previous printed sheet 5 located on the outer side 20 of the fold 10. In addition, with the solution according to the invention, two of the three rotational positions can be adapted individually and thus flexibly to the respective work situation during thread stitching printed sheet 1, which on the one hand increases the quality of the produced book block 6 and on the other hand reduces the risk of injury of the binding thread 2 used therefor.

Claims (10)

Method for stitching threads, in which individual folded printed sheets (5) are successively strung together flat and sewn to at least one sewing needle (13) and at least one hook needle (14) to form a book block (6), wherein • The at least one sewing needle (13) introduces a binding thread (2) from the outside through the fold (10) of a printed sheet (5) to be sewn inwards, between its legs (8, 9) and on an outside (20) of the fold (10) produces a first, single-stranded seam (3), • the binding thread (2) between the legs (8, 9) of the folded printed sheet (5) stored and starting from the sewing needle (13) in the form of a thread loop (25) so far in the direction of a movement path (24) of the hook needle (14) that a closed end (26) of the thread loop (25) extends beyond this movement path (24), The at least one hooked hook (14) is formed by an eyelet (22) of the same binding thread (2) formed on the outer side (20) of the fold (10) during sewing of the previous printed sheet (5) and by the fold (10) of the seam to be sewn Press sheet (5) inwardly, between the legs (8, 9) in the previously formed thread loop (25) dips, this detected during a return stroke, from the inside through the fold (10) of the sheet to be sewn (5) and through which on the outer side (20) of the fold (10) located eyelet (22) transported to the outside while on the outside (20) of the fold (10) from the first, single-stranded seam (3) spaced second, double-stranded seam (4) generated, • the hook needle (14) has a one-sided recess (16) forming a hook (15) for receiving the binding thread (2), for sewing the printed sheet (5) about its longitudinal axis (27) and the hook (15) in this case is positioned in different rotational positions, characterized in that the hook needle (14) before the taking place from the inside to the outside penetrating the fold (10) of the sheet to be sewn (5) and the eyelet (22) of the previously sewn printed sheet (5) to such its longitudinal axis (27) is rotated such that its hook (15) is positioned in a vertical plane of symmetry (33) of this eyelet (22) and on a side of the hook needle (14) facing the previously sewn printed sheet (5). A method according to claim 1, characterized in that the at least one hooked needle (14) is rotated about its longitudinal axis (27) prior to the detection of the thread loop (25), that the hook (15) of this hooked needle (14) on its sewing needle (14). 13) is positioned opposite side. A method according to claim 2, characterized in that the at least one hook needle (14) is rotated about its longitudinal axis (27) before detecting the thread loop (25) such that its hook (15) at an angle of +/- 85 °, preferably is positioned at an angle of +/- 50 ° and more preferably at an angle of +/- 15 ° with respect to a first vertical plane (34) through the fold (10) of the printing sheet (5) to be stapled. Method according to one of claims 1 to 3, characterized in that the at least one hooked needle (14) in front of the penetrating from outside to inside the eyelet (22) of the previous sheet (5) and the fold (10) of the sheet to be sewn (5 ) is rotated about its longitudinal axis (27) such that its hook (15) is aligned in a second vertical plane (32) aligned at right angles to the fold (10) of the printed sheet (5) to be sewn, on one of the previously sewn printed sheets (5). opposite side of the hook needle (14) is positioned in a start rotational position. A method according to claim 4, characterized in that for each to be sewn press sheet (5) based on in a machine control (35) of a device (1) for thread stitching or on at least one of the sheets to be sewn printed sheet (5) applied information on the nature of the Thread stitching the printing sheet (5) of a production order to be taken stitches and for separating the book block to be produced (6) starting from the start rotational position of the hook (15) of at least one hook needle (14) corresponding rotation angle (α) of the at least one hook needle (14) your Longitudinal axis (27) are determined, the at least one hook needle (14) according to the determined rotation angle (α) rotated and its hook (15) is positioned accordingly. A method according to claim 5, characterized in that the rotation of the at least one hook needle (14) to the determined rotation angle (α) and the respective positioning of the hook (15) with a drive (41), in particular with a servo motor (40). Device for stitching threads, in which individual folded printed sheets (5) are successively strung together flat and sewn to a book block (6) with a binding thread (2), the device (1) comprising at least one sewing needle (13) with a needle eye (12) and at least one hooked needle (14) arranged at a distance from the sewing needle (13) with a one-sided recess (16) forming a hook (15) for receiving the binding thread (2) and for stitching a printed sheet (5) about its longitudinal axis (Fig. 27) is rotatable, characterized in that the hook needle (14) in any rotational angle (α) about its longitudinal axis (27) rotatable and the hook (15) is formed positionable in any rotational position. Apparatus according to claim 7, characterized in that the device (1) has a device (36) operatively connected to a machine control (35) for rotating the at least one hooked hook (14) about its longitudinal axis (27), the device (36) having a Holder (37) for the at least one hook needle (14), an actuating element (39) for rotating the at least one hook needle (14) and a drive (41) for the actuating element (39). Apparatus according to claim 8, characterized in that the drive (41) has a servo motor (40). Apparatus according to claim 8, characterized in that the adjusting element (39) has a rack (38).

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