Abstract:
A cutting device is used to accomplish the transverse cutting of at last one material web. The cutting device includes a transport cylinder that is arranged to form a first cutting gap in cooperation with a first transverse cutting device. The transport cylinder is also arranged with a second transverse cutting device to form a second cutting gap.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is the U.S. National Phase, under 35 USC 371, of PCT/DE 03/00673, filed Feb. 28, 2003; published as WO 03/074402 A1 on Sep. 12, 2003 and claiming priority to DE 102 09 190.0 filed Mar. 4, 2002, the disclosures of which are expressly incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention is directed to a cutting device for the transverse cutting of at least one web of material, to a conveying cylinder of a folding apparatus, as well as to a method for operating a folding apparatus. The cutting device has a conveying cylinder which cooperates with at least a first transverse cutting device. Two material webs can contact the conveying cylinder at two offset locations. The webs may be provided with various patterns. 
   BACKGROUND OF THE INVENTION 
   A cutting device is typically employed, for example, for separating paper webs, which were imprinted on a web-fed rotary printing press. The paper webs are cut into individual signatures. 
   Generally known cutting devices of this type typically include a conveying cylinder and a cutting cylinder, which cylinders are rotatable together and delimit a gap through which a conveying path of the web of material to be cut extends. The cutting cylinder supports at least one cutting blade, which cuts each signature off the web of material when the web passes through the gap. 
   DE 35 27 710 A1 and EP 0 627 310 A1 both disclose folding apparatus, in which two folding blade cylinders act together with a folding jaw cylinder. Each folding blade cylinder is assigned a single cutting cylinder. 
   DE 93 20 814 U discloses a method for operating a folding apparatus. Two webs are separately fed to a conveying cylinder. 
   DE 239 837 C describes a cutting device for the transverse cutting of webs of material. A cutting and conveying cylinder, together with two counter-cylinders, forms respective cutting gaps. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is directed to providing cutting devices for transverse cutting of at least one web of material, to a conveying cylinder of a folding apparatus with a holding device, as well as to methods for operating a folding apparatus. 
   In accordance with the present invention, this object is attained by the provision of a cutting device that is usable for the transverse cutting of at least one web of material. The cutting device has a conveying cylinder that forms a first cutting gap in cooperation with a first transverse cutting device. The conveying cylinder may also form a second cutting gap in cooperation with a second transverse cutting device. The conveying cylinder may receive two webs of material to be cut with these two webs being fed to the conveying cylinder at two circumferentially offset inlets. Holding devices may be provided for grasping the webs of material. Various patterns or arrangements of material can be carried by the webs. 
   The advantages to be gained by the present invention lie, in particular, in that it makes possible the joining of two webs of material, which two webs of material are fed to the conveying cylinder on two conveying paths, into a common products. The present invention also permits the processing of a web of material having a large number of layers by putting the web of material together from two partial webs. 
   For several reasons, the processing webs of material, which webs are composed of a large number of layers, by the use of conventional cutting devices, entails difficulties. One difficulty is that traction rollers, which are customarily provided for setting a required tension of the web of material, only act directly on the outer layers of the web of material. Their tractive force is indirectly transferred to the inner layers only by friction of the layers of material with respect to each other. These frictional forces cannot be controlled exactly, particularly not in cases where the web must be guided around curves, i.e. where the web is looped around a roller. The tension of the inner layers of such a web is therefore all the more difficult to control, the greater the number of layers. Also, the forces required for processing the web, either during cutting, or when punching spur holes into the web, are greater, the greater the number of its layers. These forces are reduced in the cutting device. It is therefore possible to construct the cutting device lighter, and therefore less expensively than a conventional one, without a loss of quality. 
   To prevent that, during the course of the first web passing through the second cutting gap, the second cutting blade again cuts the first web, the rotation of the two cutting cylinders is preferably synchronized. During its passage through the second cutting gap, the second cutting blade strikes a cut in the first web which was made by the first cutting blade. 
   To make the striking of this cut by the second cutting blade easier, the cutting edges of the first web, which edges were formed by the first blade during its cutting, are moved apart from each other. In the course of its passage through the gap, the second blade encounters a gap of non-disappearing width in the first web. 
   Different preferred embodiments of devices and of methods for moving the cut edges apart are described in the preferred embodiments of the present invention. 
   The cutting device preferably is a part of a folding apparatus. In particular, the conveying cylinder can also function simultaneously as the folding blade cylinder of the folding apparatus. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention are represented in the drawings and will be described in greater detail in what follows. 
     Shown are in: 
       FIG. 1 , a schematic side elevation view of a folding apparatus with a cutting device in accordance with the present invention, in 
       FIGS. 2 to 5 , partial sections of a conveying cylinder and a cutting cylinder in different embodiments of the present invention, in 
       FIG. 6 , a schematic representation of a first mode of operation, and in 
       FIG. 7 , a schematic representation of another, second mode of operation. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A schematic side elevation view of a folding apparatus is represented in  FIG. 1 . This folding apparatus has two web inlets  01 ,  02  for the receipt of multi-layered webs  03 ,  04  of material, in particular paper webs  03 ,  04 , which multi-layered webs  03 ,  04  will be hereinafter identified as the inner web  03  or as the outer web  04  in what follows. Both webs  03 ,  04  pass through a respective traction roller pair  06 ,  07 , respectively for setting their tension and both webs then encounter a conveying cylinder  11  at the height of respective first and second cutting gaps  08 ,  09 . These gaps  08 ,  09  are formed between the conveying cylinder  11 , on the one hand, and one of two cutting cylinders  12 ,  13  on the other hand. In place of two inlets  01 ,  02  and two cutting gaps  08 ,  09 , it is also possible to provide three or more inlets and cutting gaps. In the course of this web travel, the webs  03 ,  04  preferably first come into contact with the conveying cylinder  11 , and thereafter with the respective cutting cylinders  12 ,  13 , i.e. the webs  03 ,  04  first loop around the conveying cylinder  11  and then around the counter cylinders  12 ,  13 . 
   Each one of the first and second cutting cylinders  12  or  13  has a circumference corresponding to at least one, and preferably corresponding to two lengths of the signatures to be produced from the webs  03 ,  04 . Each cutting cylinder  12  and  13  also supports two cutting blades  14 . 
   The circumference of the conveying cylinder  11  corresponds to the length of more than five, and in particular to the length of seven signatures. Seven counter-cutting strips, for example seven hard rubber strips, are used as backstops  15 , each of which backstops  15  works together with a cutting blade  14  when cutting the webs  03 ,  04 . A holding device  16 , for example a spur strip  16 , with spur needles  23  which can be extended as may be seen in  FIGS. 2 to 5 , is arranged on the conveying cylinder  11  adjoining each backstop  15 . 
   In the position of the cutting device represented in  FIG. 1 , a cutting blade  14  of the first cutting cylinder  12  and a backstop  15  of the conveying cylinder  11  are just passing through the first cutting gap  08  and, in the process, cooperate to cut the inner web  03 . The leading edge of the inner web  03 , which is formed by this cut, is spiked on the spur needles  23  of a spur strip  16 , which spur strip  16  had been extended briefly prior to reaching the first cutting gap  08  and which also fixedly holds the inner web leading edge on the surface of the conveying cylinder  11  during further conveying. 
   The signature cut off the inner web  03  in this process is conveyed on by the conveying cylinder  11  to the second cutting gap  09 , where the outer web  04  is placed on top of it and is also spiked by the spur needles  23  of the spur strip. 
   The rotation of the two cutting cylinders  12 ,  13  is synchronized in such a way that a cutting blade  14  of the second cutting cylinder  13  always passes through the second cutting gap  09  simultaneously with the passage of a narrow gap which has been formed between two successive signatures cut from the inner web  03  and with the passage a backstop  15 . Different techniques for forming this gap will be explained in what follows by the embodiments of  FIGS. 2 to 5 . 
   In the example represented in  FIG. 1 , the angular distance between the two cutting gaps  08 ,  09  is approximately 50°. This cutting gap angular distance can differ from the angular distance of the spur strips  16  from each other, which is typically 51.5°, or from a multiple thereof, so that cutting is not performed simultaneously at both cutting gaps  08 ,  09 . A half-integral multiple of this value is also disadvantageous from the viewpoint of vibration avoidance. 
   Following its passage through the second cutting gap  09 , each spur strip  16  supports a whole product, which is composed of a signature cut off the inner web  03  and a signature cut off the outer web  04 . Seven whole signatures, or products are formed in the course of every revolution of the conveying cylinder  11  in the same way as if both webs  03 ,  04  were fed via a common inlet  01 ,  02  in the customary way. However, since the cutting of each individual signature is spaced over two separate cutting steps at the first and second cutting gaps  08 ,  09 , the force required to be provided in each cutting step is less. The result is that a satisfactory synchronous running of the machine is easier to maintain. 
   Furthermore, seven folding blades, which are not specifically represented in  FIG. 1 , are attached to the conveying cylinder  11 , each of which folding blades is extended when reaching a gap  17  between the conveying cylinder  11  and a folding jaw cylinder  18  in order to transfer the products conveyed by the conveying cylinder  11  to the folding jaw cylinder  18  in a manner that is known per se, and to thereby fold them. The folded products are then transferred from the folding jaw cylinder  18  to a bucket wheel  19  and are deposited by the bucket wheel on a conveyor belt  21 . 
     FIG. 2  shows a detailed view of a first preferred embodiment the second cutting gap  09  and its surroundings in accordance with the present invention. Two of the seven spur strips  16  of the conveying cylinder  11  are represented in  FIG. 2  and are indicated as first and second spur strips  16 ′,  16 ″, respectively. Spur strips  16 ′,  16 ″ are each pivotable around a shaft  22  in a controlled manner and each support spur needles  23  which are oriented in such a way that their tips can out of the circumference of the conveying cylinder  11  and are each located farther away from the center of the shaft  22  than are their bases that are located in the interior of the conveying cylinder  11 . The spur needles  23  of the first spur strip  16 ′, as depicted in  FIG. 2 , are in a comparatively far or full extended position in which full extended position they previously had also passed through the first cutting gap  08 . This same position is shown in dashed lines at the location of the second spur strip  16 ″. 
   In comparison with the first spur strip  16 ′, the second spur strip  16 ″ is shown in  FIG. 2  as being pivoted back some distance farther into the interior of the conveying cylinder  11 . This retraction pivot movement results in a displacement of the line of intersection between the spur needles  23  and the surface of the conveying cylinder  11  opposite to the direction of rotation of the conveying cylinder  11 . Because of this displacement, the signature  24  held by the spur strip  16 ″ has been slightly displaced on the circumferential surface of the conveying cylinder  11  opposite to the direction of rotation of the conveying cylinder  11  in comparison with the position in which signature  24  was cut off from the inner web  03  at the first cutting gap  08 . After passing through the second cutting gap  09 , the second spur strip  16 ″ returns back into the original, extended position that is indicated by dashed lines, or even makes a transition to an even further extended position, in order to cancel, or to overcompensate for the prior retrograde displacement of the signature  24 . In this way, a narrow gap is initially formed between each signature  24  and a previous signature  27 , which had been cut off immediately prior to it, into which narrow gap the cutting blade  14  of the second cutting cylinder  13  can enter, and in this way the cutting device can push the outer web  04  against the backstop  15  and can cut it without risking the danger of again cutting one of the signatures  24 ,  27 . 
     FIG. 3  shows an alternative embodiment of the conveying cylinder  11  and of the cutting cylinder  13  in a partial sectional view that is analogous to that of  FIG. 2 . With respect to each cutting blade  14 , in this embodiment the cutting cylinder  13  has a strip  28  extending axially along, and projecting radially past its exterior circumference, which strip  28  passes through the cutting gap  09  shortly before the associated cutting blade  14 . A complementarily shaped groove  29  is provided in the circumferential surface of the conveying cylinder  11  and is located opposite the strip  28  during each passage of strip  28  through the gap. The strip  28  pushes a trailing edge area of the signature  27  cut off the inner web  03 , as well as the outer web  04 , just in advance of what will be a leading edge, into the groove  29 . Therefore, with this embodiment it is not necessary for the second spur strip  16 ″ to be pivoted outward again after its passage through the cutting gap  09  in order to create the gap  26 . 
   A third embodiment is represented in  FIG. 4 , again by the use of a partial section through the conveying cylinder  11  and the second cutting cylinder  13 . The second cutting cylinder  13  is identical to the second cutting cylinder  13  shown in  FIG. 2 . The conveying cylinder  11  of the third embodiment differs because of the arrangement of the shafts  22  around which the spur strips  16  can be pivoted. While in the embodiments of  FIGS. 2 and 3 , these shafts  22  are located ahead of the spur needles  23 , in the direction of rotation of the conveying cylinder  11 , these shafts  22  are arranged behind the spur needles  23  in the embodiment of  FIG. 4 . The orientation of the spur needles  23 , in relation to the surface of the conveying cylinder  11 , is the same in all cases. They are slightly inclined forward, opposite the normal surface, and in the direction of rotation of the conveying cylinder  11 , so that a tension, acting on the material spiked on the spur needles  23 , keeps the material pressed against the surface of the conveying cylinder  11 . 
   A changed sequence of the pivoting movement of the first and second spur strips, here identified as  16 *,  16 **, results from the changed arrangement of the shafts  22  shown in  FIG. 4 . The first spur strip  16 *, which is still far removed from the second cutting gap  09 , is in a comparatively only slightly extended position, in which slightly extended position, its spur needles  23  extend far enough past the circumference of the conveying cylinder  11  for holding an incoming inner web  03 . The first spur strip  16 * is farther extended only shortly prior to reaching the second cutting gap  09  for also now spiking the outer web  04 , as can be seen by reference to the second spur strip  16 **. In this third embodiment, the radially outward movement of the spur needles  23  causes a displacement of their intersection with the circumference of the conveying cylinder  11  in a direction opposite to the direction of movement of the conveying cylinder  11 , and therefore a movement of the leading edge of the signature  24  held by the second spur strip  16 ** away from the impact point of the second cutting blade  14  on the backstop  15 . The spur needles  23  of the third spur strip  16 *** have now been retracted radially some distance back into the conveying cylinder  11  in order to move the signature  27 , which they hold, forward in the circumferential direction and to open the gap  26  at the level of the backstop  15  in this way. 
   With this third embodiment, several directional changes in the movement of the spur needles  23 , in the course of a revolution of the conveying cylinder  11 , are avoided. 
   A fourth embodiment of the cutting device in accordance with the present invention is represented in  FIG. 5 , again in a partial sectional view that is analogous to  FIG. 4 . 
   In this fourth embodiment, first and second cylinder surface segments  32 *,  32 **, as well as other similar segments, which are not specifically shown, are arranged on the circumference of the conveying cylinder  11  between each two of first, second and third successive spur strips  16 *,  16 **,  16 *** respectively. These segments  32 *,  32 ** are utilized for temporarily increasing the circumference of the conveying cylinder  11 . Each one of these segments  32 *,  32 **, is composed of a plurality of flexible plates, which are arranged side-by-side in the axial direction of the conveying cylinder  11  and which are also spaced apart axially by gaps. During the transfer of the finished cut signatures  24 ,  27  to the folding jaw cylinder  18 , these axially spaced gaps between axially adjacent segments  32 *,  32 ** are used as respective outlet openings for tines of a folding blade, which is not specifically represented. The ends of the flexible plates are each anchored to top strips  33  which top strips  33  can be displaced in the circumferential direction of the conveying cylinder  11 . 
   The first cylinder surface segment  32 * is in a configuration in which the course of its plates corresponds to the cylindrical shape of the conveying cylinder  11 . After the passage of such a first segment  32 * through the second cutting gap  09 , its top strips  33  are displaced toward each other, so that its flexible plates, as indicated for the second segment  32 **, form a protrusion extending radially outwardly past the circumference of the conveying cylinder  11 . As a result of this radially outwardly extending protrusion, the distance between the first and second spur strips  16 * and  16 **, as measured along the surface of the conveying cylinder  11 , is greater than the distance between the second and third spur strips  16 ** and  16 ***, the latter distance corresponding to the length of the signatures  24 ,  27  produced at the first cutting gap  08 . Therefore, the bulging of the second cylinder surface segment  32 ** causes the formation of the gap  26  between the signatures  24  and  27 , into which newly formed gap  26  the cutting blade  14  of the second cutting cylinder  13  can enter. 
   The second transverse cutting device  11 ,  13  is arranged with a phase offset on the circumference of the conveying cylinder  11  for cutting. 
   The cut of the first transverse cutting device  11 ,  12  on the cutting cylinder  11  takes place closely next to the other cut of the second transverse cutting device  11 ,  13 , in particular within a distance of 10 mm next to it. 
   The first and second transverse cutting devices  11 ,  13  are arranged on the conveying cylinder  11  in the circumferential direction. 
   In all of the modes of operation of the cutting device in accordance with the present invention, a further conveying cylinder for taking over the signatures can be located downstream, in the direction of signature travel, instead of the folding jaw cylinder  18 , downstream of which future conveying cylinder a folding jaw cylinder or a belt system can be arranged. 
   It is also possible for each of the webs  03 ,  04  to have the same patterns A or B located one behind the other, i.e. in the conveying direction. Preferably these patterns A and B are imprinted by the use of at least one forme cylinder of a printing unit, which forme cylinder has two identical patterns A and B on its circumference. The webs  03 ,  04  are guided to an orientation on top of each other, so that signatures, with patterns A and B located on top of each other, are formed, each of which signatures is transferred to the downstream located folding jaw cylinder  18  in the gap  17 . The conveying cylinder  11  does not have to have an odd-number of surface divisions for this operation, but instead can also have an even-number of surface divisions, which number is preferably greater than 4 or 6. 
   Preferably, each of the patterns A, B, C, D, as seen in  FIGS. 6 and 7  identifies two newspaper pages, wherein A 1 , A 2 , B 1 , B 2 , C 1 , C 2 , D 1 , D 2  each identify a single newspaper page, also as seen in  FIGS. 6 and 7 . 
   The identification of a web  03 ,  04  is understood to represent at least one web  03 ,  04 , but preferably should be understood to be used to identify a strand consisting of several webs  03 ,  04  which are placed on top of each other. 
   The webs  03 ,  04  can each be imprinted by the use of forme cylinders of printing units which either have a pattern A or B on the cylinder circumference, in a single circumference cylinder, or two patterns A or B on the cylinder circumference, in a double circumference cylinder. With double circumference forme cylinders, two identical patterns A, A, or B, B, or two different patterns A, B can be arranged on the cylinder circumference. 
   Four modes of operation of the present invention are possible. 
   In a first and in a second mode of operation, both webs  03 ,  04  are brought together on the conveying cylinder  11  ahead of either the first inlet  01 , or the second inlet  02  and are severed in the course of a single cutting operation. 
   In this case, in the first mode of operation, the two webs  03 ,  04  have identical patterns A or C in sequence, and the same products are formed sequentially on the conveying cylinder  11  during each revolution and these same products are directly transferred to the downstream located folding jaw cylinder  18 . 
   In the second mode of operation, the webs  03 ,  04  have patterns A, B or C, D, respectively, which patterns alternate behind each other and which are alternatingly deposited on the conveying cylinder  11  during a first revolution of the conveying cylinder  11 , which is provided with an odd number of fields, and is thus a collection cylinder, and are additionally provided with a second layer of the folding product portion during the second revolution of the conveying cylinder  11 , acting as a collection cylinder. 
   In a third and in a fourth mode of operation, two webs  03 ,  04  are separately fed in, wherein in the third mode of operation the webs  03 ,  04  alternatingly bear the patterns A, B or C, D located one behind the other, as seen in  FIG. 6 . 
   In this case, during a first revolution of the conveying cylinder  11 , acting as a collection cylinder, first signatures, with the pattern A, C of each web  03 ,  04 , are conducted on all and every second spur strip  16 , so that now every second spur strip  16  carries a signature with the pattern A, C, and during the second revolution again two signatures with the pattern B, D from each web  03 ,  04  are conducted on the spur strips  16 . 
   Therefore, during the second revolution of the conveying cylinder  11 , signatures A, C, B, D on the spur strips  16  alternate with spur strips  16  carrying only signatures with the patterns A, C, wherein the signatures, i.e. the product with the pattern A, B, C, D of each second field, are transferred to the folding jaw cylinder  18 . 
   In a fourth mode of operation, the webs  03 ,  04  have identical patterns A, A, or C, C located behind each other, as seen in  FIG. 7 , so that with each revolution of the conveying cylinder  11 , each spur strip  16  carries signatures with the pattern A, C, which are directly transferred to the folding jaw cylinder  18  when they arrive there. 
   While preferred embodiments of a cutting device for the transverse cutting of at least one material web, in accordance with the present invention, have been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that a number of changes in, for example the drive for the spur strips and for the cylinders, the structure of the forme cylinders, and the like, could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the following claims.