Delivery of a sheet-processing machine

Information

  • Patent Grant
  • 6401611
  • Patent Number
    6,401,611
  • Date Filed
    Friday, December 3, 1999
    24 years ago
  • Date Issued
    Tuesday, June 11, 2002
    22 years ago
Abstract
A delivery of a sheet-processing machine having gripper rows for drawing sheets, during operation, along a conveying section having endless conveying chains bearing the gripper rows and, during operation, running through the delivery in a revolving direction, and having a pair of chain wheels which are rotatable about a common axis of rotation, are in engagement with the conveying chains and form a deflecting region of the conveying section, includes a blast-air source for expelling an air curtain actable upon a side of the sheets being drawn past the sheet-deflecting region, that side being directed towards the axis of rotation of the chain wheels, the air curtain being movable past the sheet-deflecting region in the same direction as the grippers, while the sheets passing the sheet-deflecting region are being subjected to the action of the air curtain.
Description




BACKGROUND OF THE INVENTION




Field of the Invention




The invention relates to a delivery of a sheet-processing machine, in particular, a printing machine, having gripper rows for drawing the sheets, during operation, along a conveying section having endless conveying chains bearing the gripper rows and, during operation, running through the delivery in a revolving direction, having a pair of chain wheels which are rotatable about a common axis of rotation, are in engagement with the conveying chains and form a deflecting region of the conveying section, and having a blast-air source for expelling an air curtain actable upon a side of the sheets being drawn past the sheet-deflecting region, that side being directed towards the axis of rotation of the chain wheels.




Such a delivery has become known heretofore, for example, from U.S. Pat. No. 5,456,178 which discloses an air curtain that is expelled by a blast-tube arrangement coordinated with surroundings of a transfer region wherein a respective gripper row receives a respective sheet from a sheet-guiding cylinder. Once the trailing end of a respective sheet leaves the transfer region, the sheet can then be subjected from this end, i.e., in the sheet travel direction, to blowing action from below. This has extremely adverse effects upon the smooth running or travel of the sheet, however.




In the case of relatively flexurally rigid sheets, in particular, cardboard or pasteboard, the conventional blast-tube arrangement does not provide the desired effect of preventing the sheet from striking randomly against machine parts. Quite contrarily, such a sheet would tend to collide with the conventional blast-tube arrangement.




The published German Prosecuted Patent Application (DE-AS) 20 17 417 discloses a drum provided with a gripper row that receives a sheet from an impression cylinder of a printing unit and transfers it to a following printing unit of a rotary printing machine of unit construction. For reasons not further specified, this drum has a jacket or casing that supports the sheet only along part of the extent thereof in the circumferential direction of the drum. A supporting device that supports the sheet pneumatically is provided in a space located between the sheet-supporting jacket and the gripper row, and covered by the sheets. According to an exemplary embodiment, the supporting device includes a blast tube that extends parallel to the drum axis, is disposed in the vicinity of an envelope positioned on the drum, has blow-out openings which are directed radially outwardly relative to the drum axis and circulates with the drum. This supporting device serves to prevent the formation of a curl in the sheet, the curl formation coming into abutting contact with the blanket cylinder of a respective printing unit as the sheet runs out of the nip, and further to counteract differences in register.




In the case of a delivery such as is mentioned in the introduction hereto, the problem involving the avoidance of differences in register does not arise. Rather, in such a case, there arises the general problem of transferring printed sheets to a sheet conveyor, and combining them into a pile or stack, without smearing. One of the conditions that has to be satisfied in this context is the smooth running or travel of the sheets.




SUMMARY OF THE INVENTION




It is accordingly an object of the invention to provide a delivery of the type mentioned in the introduction hereto so as to counteract the blast-air curtain adversely affecting the smooth travel of the sheets passing the sheet-deflecting region.




With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a delivery of a sheet-processing machine having gripper rows for drawing sheets, during operation, along a conveying section having endless conveying chains bearing the gripper rows and, during operation, running through the delivery in a revolving direction, and having a pair of chain wheels which are rotatable about a common axis of rotation, are in engagement with the conveying chains and form a deflecting region of the conveying section, comprising a blast-air source for expelling an air curtain actable upon a side of the sheets being drawn past the sheet-deflecting region, that side being directed towards the axis of rotation of the chain wheels, the air curtain being movable past the sheet-deflecting region in the same direction as the grippers, while the sheets passing the sheet-deflecting region are being subjected to the action of the air curtain.




In accordance with another feature of the invention, the air curtain is movable past the sheet-deflecting region synchronously with the grippers.




In accordance with a further feature of the invention, the air curtain is directable in a blowing direction with a tendency counter to the running direction of the sheets passing the sheet-deflecting region.




In accordance with an added feature of the invention, the blowing direction of the air curtain is adjustable.




In accordance with an additional feature of the invention, the air curtain is movable past the sheet-deflecting region at an adjustable distance from the conveying section.




In accordance with yet another feature of the invention, the air curtain is movable past the sheet-deflecting region at an adjustable phase angle relative to the grippers.




In accordance with yet a further feature of the invention, the delivery includes a drum body for carrying the blast-air source, and comprises a journal formed with-a cavity and received in a bearing bore of a side wall, the blast-air source being in communication with the cavity, the cavity being in communication with the bearing bore, and the bearing bore being connectable to a compressed-air generator.




In accordance with yet an added feature of the invention, the blast-air source is capable of expelling the air curtain cyclically.




In accordance with another aspect of the invention, there is provided a sheet-processing printing machine, comprising a delivery including at least one of the foregoing features.




In accordance with a concomitant feature of the invention, the sheet-processing machine is a printing machine.




Thus, in order to achieve the object of the invention, the blast-air curtain passes the sheet-deflecting region in the same direction as that of the conveying chains, while the sheets passing the sheet-deflecting region are subjected to the action of the blast-air curtain.




Such a configuration of a delivery avoids, in particular, the situation explained hereinabove wherein the trailing region of the respective sheet is subjected to blowing action from beneath. The reason therefor is that, in particular, in the case of the not absolutely necessary but nevertheless advantageously provided correspondence between the angular speeds of the grippers passing the sheet-deflecting region, on the one hand, and of the blast-air curtain passing the sheet-deflecting region, on the other hand, there is no change in the position of the blast-air curtain relative to the grippers and thus relative to the sheets, which are drawn by the grippers, within the sheet-deflecting region.




An advantageous configuration provides for the blowing direction of the blast-air curtain to be with a tendency counter to the running direction of the sheets passing the sheet-deflecting region, i.e., the blowing direction has a component that is directed counter to the running or travel direction of the conveying chains passing the deflecting region. This makes it possible, in the case wherein the blast-air curtain preferably making contact in a region of a sheet that directly adjoins the grippers drawing the sheet, for the sheet to be subject to the action of blowing or blast air over virtually the entire extent thereof, in the running direction of the sheet, without requiring the blast-air curtain to have, before it makes contact with the sheet, an extent that corresponds largely to the extent of the sheet in the running direction thereof. The blast-air source may thus be of correspondingly small construction, with the result that it may favorably be formed by just one nozzle row arranged transversely to the running direction.




Further preferred configurations provide that the blowing direction of the blast-air curtain be adjustable, that the blast-air curtain passes the sheet-deflecting region at an adjustable distance from the conveying section, and that the blast-air curtain passes the sheet-deflecting region at an adjustable phase angle relative to the grippers.




Utilizing at least one of these conditions, or else a combination of one of these conditions with at least one other, makes it possible for the action which supports sheets passing the sheet-deflecting region to be adapted to a relatively wide range of grammages and degrees of rigidity or stiffness of the sheets, and to different formats thereof, without having to modify the blast-air curtain with respect to the pneumatic parameters thereof. Accordingly, the outlay necessary for producing the blast-air curtain remains relatively low.




A further configuration preferably provides for the blast-air source to expel the blast-air curtain cyclically. Accordingly, the operation of expelling the blast-air curtain can be restricted to a period of time wherein the blast-air curtain passes the sheet-deflecting region in the same direction as the grippers, with the result that it is possible to avoid, in the surroundings of the conveyed sheets, possibly undesired flow states which occur outside the sheet-deflecting region.




Other features which are considered as characteristic for the invention are set forth in the appended claims.




Although the invention is illustrated and described herein as embodied in a delivery of a sheet-processing machine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.




The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein:











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a fragmentary diagrammatic side elevational view of a sheet-processing printing machine including a delivery, an exemplary embodiment of a blast-air source forming a structural unit with a chain-wheel pair of a chain-wheel device having conveying chains wrapped therearound, the conveying chains carrying gripper bars whereon respective gripper rows are disposed;





FIG. 2

is an enlarged fragmentary view, partly broken away and partly in section, of

FIG. 1

, showing the structural unit formed of the chain-wheel pair and the blast-air source cooperating with the gripper rows;





FIG. 2



a


is an enlarged fragmentary view of

FIG. 2

showing a detail of the blast-air source for forming a blast-air curtain;





FIG. 3

is a reduced, diagrammatic and schematic top plan view of

FIG. 2

, showing the structural unit; and





FIG. 4

is a view like that of

FIG. 3

of another embodiment of the structural unit that has been modified for the case of a single-revolution blast-air curtain.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring now to the drawings and, first, particularly to

FIG. 1

thereof, there is shown therein a delivery


1


adjoining a final processing station of a printing machine, as viewed in the sheet-processing direction. Such a processing station may be a printing unit or a post-treatment unit, for example, a varnishing unit. In the example illustrated in

FIG. 1

, the last processing station is an offset printing unit


2


with an impression cylinder


2


.


1


. The latter guides a respective sheet


3


, in a processing direction indicated by an arrow


5


representing a direction of rotation, through a nip between the impression cylinder


2


.


1


and a blanket cylinder


2


.


2


cooperating therewith and, in the example of

FIG. 1

, then transfers it to a gripper row of a single-revolution transfer drum


2


.


3


, the gripper row being arranged on the impression cylinder


2


.


1


and being openable for gripping the sheet


3


at a gripper border at the leading end of the sheet


3


. A corresponding transfer of the sheet


3


then takes place from the single-revolution transfer drum


2


.


3


to a further transfer drum


2


.


4


, namely, a half-revolution transfer drum


2


.


4


in the example at hand, which finally transfers the sheet


3


to the delivery


1


. The latter includes two endless conveying chains


6


, each of which, respectively, revolving, during operation, in the vicinity of a respective side wall of the delivery


1


along a continuous chain path. Each of the conveying chains, respectively, wraps around one of two synchronously driven driving chain wheels


7


, respectively, having axes of rotation which are aligned with one another and, in the example of

FIG. 1

, is guided over deflecting chain wheels


8


, respectively, which are located downline of the driving chain wheels


7


, as viewed in the sheet-processing direction, with the result that a respective conveying chain


6


runs through a continuous chain path. Extending between the two conveying chains


6


are gripper bars


9


which are borne by the conveying chains


6


and have grippers


9


.


1


which pass through gaps between grippers arranged on the transfer drum


2


.


4


and, in the process, receive a respective sheet


3


by gripping the gripper border at the leading end of the sheet


3


immediately before the grippers arranged on the transfer drum


2


.


4


are opened, transport the sheet


3


beyond a sheet-guiding device


10


to a braking station


11


and open after the sheet


3


has been transferred to the braking station


11


. In the braking station


11


, the sheet


3


is braked to a depositing speed that is reduced relative to the processing speed and, after the depositing speed has been reached, the sheet


3


is finally released, with the result that a respective, then slowed-down sheet


3


finally makes contact with leading-edge stops


12


and, while being aligned at the latter and at trailing-edge stops


13


, which are located opposite the leading-edge stops


12


, forms a pile


14


together with preceding and/or following sheets


3


, it being possible for the pile to be lowered by a lifting mechanism to the extent that the pile


14


increases. Of the lifting mechanism, only a platform


15


carrying the sheet pile


14


, and lifting chains


16


carrying the platform


15


and represented in phantom are shown in FIG.


1


.




Along the path of the conveying chains


6


between the driving chain wheels


7


, on the one hand, and the deflecting chain wheels


8


, on the other hand, the conveying chains


6


are guided by non-illustrated chain-guide rails which determine the chain paths of the chain strands. In the case at hand, the chain strand that is located predominantly at the bottom in

FIG. 1

transports the sheets


3


along a conveying section that extends from the location where the sheets


3


are transferred from the transfer drum


2


.


4


to the delivery


1


as far as a location at which a cam


4


, that is disposed in the vicinity of one of the deflecting chain wheels


8


, actuates a non-illustrated roller lever that is operatively connected to the grippers


9


.


1


, and thus opens the grippers


9


.


1


which had been closed under spring tension, the sheets


3


being thereby released. That portion of the chain path through which the chain strand located predominantly at the bottom runs is followed by a sheet-guiding surface


17


that is directed towards that portion of the chain path and is formed on the sheet-guiding device


10


. During operation, a supporting air cushion is preferably formed between the sheet-guiding surface and the sheet


3


, respectively, guided thereover. For this purpose, the sheet-guiding device


10


is provided with blast-air nozzles which open out into the sheet-guiding surface


17


, those nozzles, in their entirety, being represented in

FIG. 1

symbolically in the form of a stub


18


.




In order to prevent the printed sheets in the sheet pile


14


from sticking to one another, a drier


19


and a powder sprayer


20


are provided along the path of the sheets


3


from the driving chain wheels


7


to the braking station


11


.




In order to avoid excessive heating of the sheet-guiding surface


17


by the drier


19


, a coolant circuit is integrated in the sheet-guiding device


10


, the circuit being indicated symbolically in

FIG. 1

by an inlet stub


21


and an outlet stub


22


on a coolant tray


23


assigned to the sheet-guiding surface


17


.




In the example of

FIG. 1

, the conveying length or section has a horizontal portion, a branch located upline from and sloping upwardly towards the horizontal portion, and a sheet-deflecting region


24


located upline from the sloping branch and, even when the sheets are printed only on one side thereof, constituting a problematic region in as much as the sheets, without any further measures being provided, may execute uncontrolled movements which may result in smearing of freshly printed ink.




One of these measures is, for example, providing, radially outside that position of the gripper path through which the grippers


9


.


1


pass and namely constituting the sheet-deflecting region


24


, a sheet-guiding device


10


′ that is activatable pneumatically and is approximately of the same extent as the sheet-deflecting region


24


, as viewed in the running or travel direction of the grippers


9


.


1


. The applicant of the instant application has previously described advantageous configurations for the sheet-guiding device


10


′ in U.S. Pat. No. 5,456,178, and reference may be had thereto advantageously with respect to these configurations.




Another of the mentioned measures calls for directing a blast-air curtain


24


towards the sheet


3


passing the sheet-deflecting region


24


for supporting the sheet


3


. The blast-air curtain is expelled by a blast-air source


26


which, in contrast with the delivery mentioned in the introduction hereto, is not fixed in position, but rather, passes the sheet-deflecting region


24


in the same direction as do the grippers


9


.


1


.




In the case of the aforementioned, not absolutely necessary, but preferably provided, configuration wherein the blast-air curtain


25


passes the sheet-deflecting region


24


synchronously with the grippers


9


.


1


, a particularly straightforward construction of the sheet conveyor is achieved and, more precisely, as provided in the exemplary embodiment of

FIG. 1

, the blast-air source


26


forms a structural unit with the chain-wheel pair formed by the driving chain wheels


7


.




In this regard, the blast-air source


26


is preferably formed by the use of a tube


26


.


1


that is disposed parallel to the axis of rotation of the driving chain wheels


7


and has, in the longitudinal direction thereof, a row of blast-air openings


26


.


2


, of which one opening is visible in

FIG. 2



a


. The preference for a blast-air source


26


configured in such a way does not exclude the possibility of the blast-air curtain


25


, which passes the sheet-deflecting region


24


as mentioned, being expelled from blast-air sources having other configurations.




As is illustrated in

FIGS. 2 and 3

, the structural unit in the exemplary embodiment shown therein is constructed as follows.




The two driving chain wheels


7


are connected to a chain-wheel spindle


27


so as to be fixed against rotation relative thereto, the spindle


27


having journals


27


.


1


and


27


.


2


. In the vicinity of a respective one of the chain wheels


7


, the chain-wheel spindle


27


bears a respective hub


28


that is adjustable in the circumferential direction of the chain-wheel spindle


27


and is connected in a forcelocking manner thereto. In this regard, it is noted that a forcelocking connection is one which connects two elements together by force external to the elements, as opposed to a formlocking connection which is provided by the shapes of the elements themselves. Spokes


29


are fastened onto the hubs


28


so that they can be adjusted in the longitudinal direction thereof; more precisely, in the embodiment of

FIGS. 2 and 3

, the chain wheels


7


are half-revolution driving chain wheels


7


, and two spokes


29


are fastened on each hub


28


. Based upon the half-revolution construction of the driving chain wheels


7


, as is apparent in

FIG. 3

, in particular, two blast-air sources


26


are provided, a respective one of the blast-air sources


26


being formed by a tube


26


.


1


, in the manner explained hereinbefore. The respective tube


26


.


1


is closed off at the ends thereof by a respective stub


30


which projects beyond the respective tube


26


.


1


. A respective bore formed in the respective radially outer end of the spokes


29


and extending parallel to the axis of rotation of the driving chain wheels


7


slidably receives therein one of the stubs


30


, respectively. A respective tube


26


.


1


that is installed in this manner and is used for forming a blast-air source can thus be rotated in relation to the longitudinal axis thereof, and a given rotary position thereof is fixable by a tightening screw


31


that is inserted into at least one of the spokes bearing the tube


26


.


1


and that acts upon one of the stubs


30


. Accordingly, the blowing direction of the blast-air curtain that is expelled, during operation, by the blast-air source


26


, in this case, the tube


26


.


1


having a blast or blowing-nozzle row, can be adjusted, and it is preferably adjusted so that it is directed with a tendency counter to the running or travel direction of the sheets passing the sheet-deflecting region


24


.




The structural unit described thus far, which includes the blast-air source


26


and the driving chain wheels


7


, forms a drum body


32


which is received rotatably by the journals


27


.


1


and


27


.


2


, respectively, in bearing bores


33


.


1


and


34


.


1


provided in side walls


33


and


34


of the sheet conveyor


1


. The chain-wheel spindle


27


is of hollow construction so that a cavity


35


which communicates with the bearing bore


33


.


1


is formed in the journal


27


.


1


. This is realized in the example or embodiment shown in

FIG. 3

, by the chain-wheel spindle


2


being formed as a tube


27


′ with respective spindle portions


27


″ and


27


″′ welded onto the ends of the tube


27


′, the spindle portion


27


″ being formed with a through-passage bore opening into the tube


27


′ and forming the cavity


35


.




The journal


27


.


1


projects into the bearing bore


33


.


1


only over part of the depth of that bearing bore


33


.


1


, and the end of the bearing bore


33


.


1


that is directed away from the chain-wheel spindle


27


is closed off by a cover


36


that has a connection nipple


37


via which the bearing bore


33


.


1


can be connected to a compressed-air generator


38


.




Between a respective tube


26


.


1


, provided for forming the respective blast-air source


26


, and the tube


27


′ of the chain-wheel spindle


27


, a connection is produced by flexible lines


39


, with the result that, ultimately, a respective blast-air source


26


communicates with the cavity


35


.




This allows the revolving blast-air sources


26


to be supplied with compressed air without requiring any rotary lead-through.




Because the spokes


29


, which carry a respective blast-air source


26


, are fastened onto the hubs


28


so that they can be adjusted in the longitudinal direction thereof, the blast-air curtain


25


can pass the sheet-deflecting region


24


at an adjustable distance A (note

FIG. 2

) from the conveying section.




Because the tubes


26


.


1


, which form the blast-air sources


26


, are carried, via the spokes


29


, by the hubs


28


, which are connected to the chain-wheel spindle


27


so that they can be adjusted in circumferential direction, the blast-air curtain


25


can pass the sheet-deflection region


24


at an adjustable phase angle φ (note

FIG. 2

) relative to the grippers


9


.


1


.




The grippers


9


.


1


, for their part, pass the sheet-deflecting region


24


during operational rotation of the drum body


32


, which includes, in particular, the driving chain wheels


37


having, wrapped around them, the conveying chains


6


, which carry the gripper bars


9


.




For the operational rotation of the drum body


32


, the chain-wheel spindle


27


, in the exemplary embodiment shown in

FIG. 3

, is connected, so as to be fixed against rotation relative thereto, to a driving gear wheel


40


that forms a constituent part of a gear train connected to a drive system.




As is explained hereinbelow, the delivery which has been described thus far has also proven to be particularly advantageous for further reasons.




As is indicated in

FIG. 1

, the sheet-guiding device


10


is preceded by a sheet decurler


41


that is usually used in the case of sheets which have been printed on one side thereof, and in the case at hand, on that side of the sheet that is directed away from the sheet-guiding device


10


and, in this regard, by a negative pressure in a decurling nip perpendicular to the side edges of the sheets, which draws the sheets into the decurling nip. However, the negative pressure is fully effective in this sense only when the respective sheet has positioned itself in contact with the sheet decurler


41


. Because the latter is usually arranged in close proximity to the outlet region of the sheet-deflecting region, the operation wherein the sheet


3


positions itself against or in contact with the sheet decurler


41


is aided by the blast-air curtain


25


passing the sheet-deflecting region


24


.




Furthermore, the preferred configuration of the blast-air source


26


in the form of the tube


26


.


1


carried by the spokes


29


provides the advantages of good accessibility to the sheet-deflecting region


24


for cleaning purposes and of a good view into the sheet-deflecting region


24


which, particularly in the case of sheets which are printed on both sides, is extremely helpful for adjusting the pneumatically activatable sheet-guiding device


10


′.




Furthermore, the adjustability of the blast-air source


26


with respect to the following parameters: the blowing or blast direction of the blast-air curtain


25


, the distance of the blast-air source


26


from the conveying section in the sheet-deflecting region


24


and the phase angle φ of the blast-air source


26


relative to the grippers


9


.


1


passing the sheet-deflecting region


24


, allow the spatial position of the blast-air curtain


25


to be adjusted in relation to the drum body


32


so that a compromise is achieved in terms of the effect of the blast-air curtain


25


on sheets with different grammage and different degrees of rigidity or stiffness. Of course, it is also possible to maintain just individual ones of the foregoing parameters for a number of different print jobs.




A further possible way of influencing the effect of the blast-air curtain is to change the pressure of the compressed air fed to the blast-air source


26


. This is indicated in

FIG. 3

by the adjustable throttle


42


.





FIG. 4

illustrates an exemplary embodiment for expelling the blast-air curtain


25


cyclically from the blast-air source


26


, more precisely, using the example of a structural unit that includes the blast-air source


26


and the two driving chain wheels


7


in the form of a drum body


32


′ which, although it is the same in principle as the drum body


32


according to

FIG. 3

, differs from the latter in that the drum body according to

FIG. 3

is a half-revolution drum body, and the drum body according to

FIG. 4

is a single-revolution drum body, and thus has merely one tube


26


.


1


constituting the blast-air source


26


. In order to realize the cyclic expulsion, the bearing bore


33


.


1


corresponding to the exemplary embodiment according to

FIG. 3

can be connected to the compressed-air generator


38


via an on/off valve


43


which, in this case, is alternately opened and closed, by way of example, mechanically by a cam


44


which, during operation, rotates synchronously with the drum body


32


′. In this case, the phase position of the cam


44


relative to the drum body


32


′ is adjusted so that the on/off valve


43


is open when the blast-air source


26


passes the sheet-deflecting region


24


.




An operation wherein the tubes


26


.


1


provided for forming the half-revolution drum body


32


according to

FIG. 3

are subjected to the action of compressed air in a corresponding, but alternating, cyclic manner is realized in an analogous manner and with a modification of the drum body


32


and the connection thereof to the compressed-air generator


38


, which has the effect that the two tubes


26


.


1


, which expel a blast-air curtain


25


during operation, can be connected to the compressed-air generator


38


independently of one another.



Claims
  • 1. A delivery of a sheet-processing machine having a conveying section with endless converying chains, the sheets each having a respective leading edge, and gripper rows for drawing sheets, during operation, along the conveying section in a running direction, said endless conveying chains bearing the gripper rows and, during operation, running through the delivery in a revolving direction, and having a pair of chain wheels which are rotatable about a common axis of rotation, are in engagement with the conveying chains, and form a deflecting region of the conveying section, the delivery comprising:a blast-air source expelling an air curtain meeting the leading edge of each respective sheet and acting upon a side of the sheets being drawn past the sheet-deflecting region, the side being directed towards the axis of rotation of the chain wheels, said air curtain being movable with the chain wheel past the sheet-deflecting region in the same direction as the grippers, while the sheets passing the sheet-deflecting region are being subjected to the action of said air curtain; said air curtain blowing in a blowing direction, and said blowing direction being counter to the running direction.
  • 2. The delivery according to claim 1, wherein said air curtain is movable past the sheet-deflecting region synchronously with the grippers.
  • 3. The delivery according to claim 1, wherein the sheet-processing machine is a printing machine.
  • 4. The delivery according to claim 1, wherein said blowing direction of said air curtain is adjustable.
  • 5. The delivery according to claim 1, wherein said air curtain is movable past the sheet-deflecting region at an adjustable distance from the conveying section.
  • 6. The delivery according to claim 1, wherein said air curtain is movable past the sheet-deflecting region at an adjustable phase angle relative to the grippers.
  • 7. The delivery according to claim 1, including:a side wall having a bearing bore; a journal formed with a cavity received by said bearing bore; a drum body carrying said blast-air source, said blast-air source communicating with said cavity, said cavity communicating with said bearing bore, and said bearing bore being connectable to a compressed-air generator.
  • 8. The delivery according to claim 1, wherein said blast-air source is capable of expelling said air curtain cyclically.
  • 9. A sheet-processing printing machine, comprising a delivery according to claim 1.
Priority Claims (1)
Number Date Country Kind
198 55 713 Dec 1998 DE
US Referenced Citations (6)
Number Name Date Kind
3986455 Jeschke et al. Oct 1976 A
4836104 Duarte Jun 1989 A
4919048 Tyler Apr 1990 A
5456178 Henn et al. Oct 1995 A
5599013 Detmers et al. Feb 1997 A
5626075 Detmers et al. May 1997 A
Foreign Referenced Citations (6)
Number Date Country
2017417 Jul 1972 DE
2354418 Apr 1980 DE
39 39 209 Jun 1990 DE
0706882 Apr 1996 EP
1464165 Feb 1977 GB
2169243 Jul 1986 GB