Abstract:
A folding drum of a folding device is comprised of at least one folding element and a transmission unit. The transmission unit has at least one toothed wheel which is coaxially arranged with respect to the rotational axis of the folding drum. The toothed wheel can be moved in the axial direction of the folding drum between at least two positions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This patent application is the U.S. National Phase, under 35 USC 371 of PCT/DE 03/00268, filed Jan. 31, 2003; published as WO 03/072476 A1 on Sep. 4, 2003, and claiming priority to DE 102 08 017.8 filed Feb. 26, 2002 and to DE 102 08 292.8 also filed Feb. 26, 2002, the disclosures of which are expressly incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention is directed to folding drums of a folder. The folding drum has at least one folding element arranged on a support and a gear unit. 
   BACKGROUND OF THE INVENTION 
   It is the general purpose of a folding drum to temporarily convey a product, which is to be folded in a folder, and to push the product into a folding jaw of a folding jaw cylinder in an orientation suitable for folding, or, depending on the type of the folder, to transfer the product to two folding rollers, which two folding rollers draw the product, with the desired fold line at the front, into a gap formed between them and to thus fold the product in this way. The folding drum has a plurality of movable folding blades for accomplishing this purpose, which movable folding blades can be extended through openings in a shell of the folding drum in order to insert the product to be folded into a folding jaw or into a gap between two folding rollers. 
   The extending and retracting movement of the folding blade is coupled to the rotation of the folding drum by the use of a gear. Folders are known, wherein the coupling can be cancelled for one of the two folding blades in the folding drum, and the folding blade can be stopped. This stoppage of one of the folding blades allows for so-called collection production. A product can be transferred to the folding drum at a transfer point and can make a complete revolution on the folding drum without being pushed off by a folding blade. When the product again passes the transfer point, a second product is placed on top of the first one, and both products are moved on together by the folding drum. If now both products are pushed off together by the folding blade, they are folded together. 
   DE 195 11 054 C2 discloses a drive mechanism for a folding blade of a folding drum. Driving of the folding blade is provided via a central gear wheel. 
   DE 12 22 082 B1 describes a wheel folder, whose folding blades can be adjusted by an adjusting gear via an axially displaceable gear wheel. 
   A folding drum of a folder with a folding blade arranged on a support is known from GB 1 059 158 A. A gear wheel, which is arranged coaxially with respect to the axis of rotation of the support is provided, which gear wheel, in one mode of operation, has a number of revolutions which is different from that of the folding drum. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is directed to providing folding drums for a folder. 
   In accordance with the present invention, this object is attained by the provision of a folding drum of a folder having at least one folding element arranged on a support. A gear unit, which has at least one central gear wheel can be arranged coaxially with respect to a rotating shaft of the support. This gear wheel can be shifted axially between two positions. This gear wheel can also have a number of revolutions that is different from the number of revolutions of the folding drum. The folding element may also rotate at one of first and second different numbers of revolutions, or can be stopped. The rotating shaft of the folding element may be located eccentrically with respect to the rotating shaft of the folding drum. 
   One of the two gear wheel disks is fixed, while the other gear wheel disk rotates as a function of the production mode which is selected. 
   For engagement, the folding drum is stopped in a defined position, because the gear coupling is unequivocal. Alternatively, the tooth coupling can catch slippingly while the folding drum rotates. 
   With this folding drum structure, in accordance with the present invention, switching from single to collection production is possible more rapidly and is simpler than with constructions which were previously used. 
   For the coupling of the first and second gear wheel disk to each other, which is necessary for accomplishing single production, these gear wheel disks are usefully equipped with complementary tooth arrangements, which tooth arrangements can be brought into engagement or out of engagement by axially displacing the first wheel disk. 
   By the provision of irregular distances or widths of the teeth, these tooth arrangements have been configured in such a way that they can be be brought into engagement by the use of only a small number “m” of evenly distributed rotary positions of the two wheel disks with respect to each other. The number “m” is a function of the gear ratio of the groups of gears. If, with the frame of the gear unit assumed to be fixed, the gear groups convert one revolution of the center wheel to a whole number “n” of revolutions of the folding blades, “m” can be any arbitrary whole number divisor of “n”, including 1 or “n”. Because of this, it is assured that switching back to single production takes place only when the folding blade, which had previously been deactivated during collection production, is in a correct phase position. 
   It is possible, in particular, to fix a single defined position. 
   The first wheel disk preferably has a further, or an additional tooth arrangement, which further tooth arrangement is complementary to a tooth arrangement at the frame of the gear unit, and which can be brought into engagement with the first gear wheel disk by displacing the latter. This further tooth arrangement is used for stopping the folding blade coupled to the first wheel disk during collection production. These tooth arrangements can be brought into engagement with each other in a multitude of rotary positions, so that switching from single to collection production can take place in any arbitrary orientation of the folding drum. 

   
     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 perspective view of a folding drum, with which the present invention can be used, in 
       FIG. 2 , a view, in the same perspective as in  FIG. 1 , of the internal structure of the folding drum depicted in  FIG. 1 , in 
       FIG. 3 , a schematic representation of a gear unit for the folding drum represented in  FIG. 1 , and in 
       FIG. 4 , an end view of a wheel disk in accordance with the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring initially to  FIG. 1 , there may be seen a preferred embodiment of a folding drum of a folding device in accordance with the present invention. Three groups of slits  02 , each group of slits  02  being spaced at an angular distance of 120° in a circumferential direction from each other, have been formed in a drum shell  01  of the folding drum which is represented in  FIG. 1 . A plurality of protruding projections  03  are shown extending radially through the group of slits  02  which are located at the top of the drum shell  01 , as seen in  FIG. 1 , which protruding projections  03  are a part of a folding element  04 , such as for example, a folding blade  04 . The folding blade  04  is arranged on a support, which structure will be explained in greater detail subsequently, in connection with  FIG. 2 . 
   Various function groups, such as, for example, grippers or spur needle strips, for use in holding a product taken along by the folding drum, can be arranged on or at the drum shell  01 , which function groups are not shown in  FIG. 1  for simplifying the representation in  FIG. 1  and which function groups will also not be described, since they are generally known to one skilled in the art and are not further developed or modified by the present invention. 
   Two end flanges  06 , each with an enlarged central opening  07 , which central opening  07  is concentric with respect to a longitudinal axis of the drum shell  01 , are located at the end faces of the drum shell  01 , as seen in  FIG. 1 . A shaft  08  has been formed at the openings  07  and is used for the rotatable support of the folding drum in a frame, which is not specifically represented, of a folder. 
   A shaft  09  which supports the internal structure of the folding drum, extends eccentrically through the central opening  07  of the end flange  06 . 
   As is shown in  FIG. 2 , the eccentrically located shaft  09  has, in the interior of the folding drum, two arms  11 , which project in opposite radial directions from shaft  09 , and a gear unit  12 , which areas  11  and gear unit  12  support two folding blade shafts  13 ,  28 , which two folding blade shafts  13  and  28  are rotatable around axes of rotation which are parallel to the shaft  09 . The housing of the gear unit  12  is rigidly connected with the section of the shaft  09  facing the viewer, as depicted in  FIG. 2 , and is rotatable in the interior of the folding drum together with this section of the shaft  09 . On the far side of the gear unit  12 , in the perspective view shown in  FIG. 2 , the shaft  09  is extended by a second shaft section  14 , which is here called a second gear wheel disk shaft  14  for reasons which will become clear in connection with the subsequent discussion of  FIG. 3 . This second gear disk shaft  14  is structured for being mounted non-rotatably in a lateral plate of the folder. A first shaft section  16 , which is a so-called first gear wheel disk shaft  16 , extends through an axially extending, centralhollow space or bone in the second gear wheel disk shaft  14 ; 
     FIG. 3  shows the internal structure of the gear unit  12 . The first and second gear wheel disk shafts  16 ,  14 , respectively have been rotatably passed through an opening of the housing  17  or of the frame of the gear unit  12 , and respectively support a first gear wheel disk  18  or a second gear wheel disk  19 . Since the second gear wheel disk  19  is rigidly connected with the second gear wheel disk shaft  14 , it does not follow a rotation of the gear unit  12  around the axis of the shaft  09 . In this way, when the gear unit  12  rotates, it drives a gear group constituted by an intermediate gear wheel  21 , which intermediate gear wheel  21  is rotatable around a shaft that is connected with the housing  17 , and also drives a gear wheel  22  that is fastened on the folding blade shaft  13 . While the gear unit  12  rotates around the axis of the eccentrically positioned shaft  09 , the folding blade shaft  13  moves on a circular path around the shaft  09 , and at the same time, rotates around its own axis. In the process, the tip or tips  03  of the folding blade  04  mounted on the folding blade shaft  13  describes a cycloid. Due to the eccentric arrangement of the shaft  09  with respect to the drum shell  01 , the folding blade  04  is extended through the slits  02  of the drum shell  01  at only one location of its cycloidal track. The gear ratio of the gear group  19 ,  21 ,  22  must be selected in such a way, that the folding blade shaft  13  performs one entire revolution around itself with every revolution of the gear unit  12 . In the situation under discussion, the gear ratio of the gear group  19 ,  21 ,  22  has been selected to be such that, with the housing  17  assumed to be fixed, one revolution of the second gear wheel disk  19  drives “n”=3 evolutions of the folding blade  04 . 
   The first gear wheel disk  18  can be displaced axially between first and second positions by axially displacing the first gear wheel disk shaft  16 . In the first position, the first gear wheel disk shaft  16  is coupled with the second gear wheel disk shaft  14  via first tooth arrangements  23 ,  24  arranged on the facing front ends of the two gear wheel disks  18 ,  19 , and in this way is kept immovable with regard to the frame of the folder. In this position, the first gear wheel disk  18  drives another gear wheel group  26 ,  27 , which consists of an intermediate gear wheel  26  and a gear wheel  27  of the second folding blade shaft  28 . In this state, the folding blade  04  of the second folding blade shaft  28  moves on the same cycloidal track as that of the first folding blade shaft  13 . This state corresponds to single production. 
   In the second axial position of the first gear wheel disk  18 , it is coupled by the use of a second tooth arrangement  29  on its second end face with a tooth arrangement  31 , which is fixedly connected with the housing  17 . In this position, the first gear wheel disk  18  follows the rotation of the housing  17 , and the folding blade  04  of the second folding blade shaft  28  moves on a circular track, on which it does not extend out of the folding drum, i.e. it does not move with respect to the cylinder. This state corresponds to collection production. 
   The second tooth arrangements  29 ,  31  consist of a large number of evenly arranged teeth, which permit their engagement with each other in a plurality of orientations, which plurality of orientations are respectively separated from each other by small angles of rotation. Thus, even when tooth tips of the two second tooth arrangements  29 ,  31  meet each other in the course of the axial displacement of the first gear wheel disk  18 , in relation to the tooth arrangement  31 , a slight turning of the housing  17  is sufficient to make an engagement possible. In contrast thereto, as can be seen in  FIG. 4 , the first tooth arrangements  23 ,  24  each have a small number of teeth  32 , which are of irregular length and which are arranged at irregular distances in order to permit an engagement with each other only in three orientations of the two gear wheel disks  18 ,  19 . It is assured by this structural feature that, when restoring the coupling between the gear wheel disks  18 ,  19 , the folding blade  04  of the temporarily stopped second folding blade shaft  28  is in the same position as prior to the release of the coupling. This could require that, in the course of switching from collection to single production, the folding drum must initially be rotated some distance until the tooth arrangements  23 ,  24  can be brought into engagement. 
   The teeth  32  of the first tooth arrangements  23 ,  24  can also be arranged in such a way that an engagement is only possible in a single position of rotation. 
   If the gear ratio of the gear groups  19 ,  21 ,  22 , and  18 ,  26 ,  27  would correspond, for example, to “n”=4 revolutions of the folding blade shafts  13 ,  28  per revolution of the gear wheel disks  18 ,  19 , the teeth  32  could also be arranged in such a way that they would permit “m”=1, 2 or 4 engagement positions. 
   The change of the number of revolutions of the folding elements  04  is provided by the use of an actuating device, which is arranged coaxially with respect to the rotating shaft  09 ,  14 ,  16  of the support, i.e. the shaft  09  or the shaft sections  14  or  16 , particularly in the shaft journal. 
   The rotating shaft of the folding drum, which is not specifically shown, and the rotating shaft  09 ,  14 ,  16  of the support are arranged eccentrically with respect to each other. Each folding element  04  is rotatingly arranged on its further rotating shaft  13 ,  28 , as discussed above, each of which rotating folding blade shaft  13 ,  28  is arranged eccentrically with respect to the rotating shaft  09 ,  14 ,  16  of the support. 
   The described gear structure can also be used for a folding drum which has folding jaws  04  in place of folding blades  04 , i.e. for a folding jaw cylinder. 
   While preferred embodiments of a folding drum of a folding device, in accordance with the present invention, have been set forth fully and completely hereinabove, it will be obvious to one of skill in the art that various changes in, for example, the supports for the folding drum, the type of web being folded, 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 appended claims.