Patent Application
20070234863
This application claims priority from European Patent Application No. EP 06 005 836.9, filed Mar. 22, 2006, the entire disclosure of which is incorporated herein by reference thereto.
The present invention relates to a cross cutting device and to a method for operating such a cross cutting device.
When individual products, for example individual sheets, are manufactured from an endless flat material web, in particular made of paper, there may be the problem that two successive products cannot be separated from one another by a single cut. This is the case in particular if the position of the edges of a sheet is defined in relation to register marks or water marks and the like. This makes it necessary to cut out portions from the flat material web.
Cross cutting devices having two cross cutting units for manufacturing individual products from a flat material web and for separating cut-out portions from the flat material web or from the product are disclosed, for example, in documents EP-A 0622320, EP-A 1570960, DE-A 3145912, U.S. Pat. No. 5,199,341 and WO-A 95/01245. The cross cutting units each have a fixed blade and a rotating blade arranged on a rotational element, and are spaced apart from one another in the direction of transportation of the flat material web. In a device of the generic type according to EP-A 0622320 or DE-A 3145912 the second rotational element has a zone which can be connected to a suction device and has suction openings and which serves to secure the front edge of the portion to be cut from the flat material web to the second rotational element before the cutting process, and thus to rotate it out of the plane of transportation. The connection to the suction device is interrupted again after the separation of the cut-out portion so that the cut-out portion either drops off under the force of gravity, is scraped off mechanically by the second rotational element or is pushed away with blown air and can be removed. However, the front edge of the following product which is already separated or is still to be separated from the material web should not be deflected out of the plane of transportation but rather be conveyed onward in the direction of transportation. In order to ensure this, suction air is applied to the suction openings in a clocked fashion within a processing cycle.
The processing cycle is understood to mean the processes which lead to the separation of in each case one product and, if appropriate, in each case one cut-out portion, in particular the production of a first separating cut for separating the product and the following material web, and the production of a second separating cut for separating the cut-out portion and the product. The first separating cut is usually carried out by the first cross cutting unit which is located downstream in the direction of transportation, and the second separating cut is carried out by the following, second cross cutting unit. If a cut-out portion is not produced, the second separating cut is dispensed with. Instead of complete separation, it is, for example, also possible to form a perforation.
A problem with the known cross cutting devices is that the size and position of the suction zone is permanently predefined. In the devices according to EP-A 0622320 and DE-A 3145912, the suction zone is, for example, arranged directly downstream of the rotating blade in the direction of transportation, or in the region of the rotating blade. As a result of this the maximum width of the cut-out portion which can be secured to the rotatable element is determined by the width of the suction zone. In order to be able to hold even relatively large cut-out portions, the suction zone must therefore be relatively wide. As a result of this in turn incorrect air gets into the suction system when cut-out portions which are narrow compared to the width of the suction zone are sucked in. As a result, the suction device is loaded and the suction power is adversely affected to a large degree.
The invention is therefore based on the object of further developing the known cross cutting devices in such a way that the device can easily be adapted to different formats of the cut-out portion without greatly loading the suction device.
The object is achieved by means of a cross cutting device for manufacturing cut-out portions from a flat material web that is moved in a direction of transportation, including a first cross cutting unit for the flat material web, said first cross cutting unit having a first fixed blade and a first rotating blade arranged on a first rotational element, a second cross cutting unit for the flat material web, said second cross cutting unit being spaced apart from said first cross cutting unit in the direction of transportation and having a second fixed blade and a second rotating blade arranged on a second rotational element. The second rotational element can be connected to a suction device such that a cut-out portion is at least temporarily secured on the second rotational element. The second rotational element contains, along a circumferential face, a plurality of zones to which suction air can be applied individually and/or in combination in order to secure cut-out portions of different formats.
The object is also achieved by means of a method for operating a cross cutting device including the steps of selecting the zones of the second rotational element in accordance with a format of the cut-out portion; and correspondingly clearing or interrupting entries to the zones.
Advantageous further developments of the device and of the method are specified in the dependent claims, the description and the drawings.
According to the invention, the second rotational element contains, along its circumferential face, a plurality of zones, to which suction air can be applied individually or in combination, in order to secure cut-out portions of different formats. For this purpose, preferably a plurality of suction chambers which are separated from one another and which are each connected to a suction zone and can be connected to a suction device, for example a vacuum pump, are provided in the interior of the rotational element. In this context, the connection to the suction device for individual chambers or for a combination of chambers can be cleared or interrupted in order to obtain a resulting overall suction zone with a specific shape and size which is adapted to the format of the cut-out portion. The clearing or interruption of the suction air supply is brought about with a control device which closes or opens the entries to the chambers, preferably mechanically. For this purpose, preferably one control element which can move between various positions and which is preferably moved along with the second rotational element is provided. When there is a fixed suction air port, the position of the control element in relation to the rotational element thus determines the application of suction air to the individual chambers and the position of the element relative to the suction air port by supplying suction air within one processing cycle. Through the latter it is possible to ensure that only the front edge of a cut-out portion is sucked in, but not the front edge of the actual product which has to be conveyed onward in the plane of transportation.
The invention therefore advantageously permits suction air to be applied to the suction zone of the second rotational element essentially only over the surface of the cut-out portion. It thus prevents incorrect air getting into the suction system. This is promoted by the connection of the suction zones to the suction air source only at specific times within a processing cycle.
In one advantageous development of the invention, blown air is applied to the suction chambers or suction zones after the separation of the cut-out portion from the material web. As a result the cut-out portion can easily be removed from the second rotational element.
In a further advantageous development of the invention, additional measures ensure that the material web and the product move in the desired way. In this context, blown air is used in addition to the suction air. The measures described below can advantageously also be used in cross cutting devices without a second cross cutting unit, i.e. without the possibility of producing cut-out portions. In this case, the suction air system described above can be dispensed with.
One of these measures consists in providing an additional blowing zone with corresponding blown air supply on the second rotational element. Said blown air supply serves to deflect the front edge of the material web away from the rotational element in the direction of the plane of transportation after the separation of a cut-out portion, in order to facilitate reliable onward transportation in the plane of transportation. If no cut-out portion is produced, the transfer of the front edge to a following transportation device is thus also simplified.
A further one of these measures comprises influencing the movement of the front edge of the material web in the region of the stationary blade of a cross cutting unit by a suitable air supply. Blown air is preferably blown in in the region of the stationary blade in such a way that it runs essentially parallel to the plane of transportation, for example through a blown air duct which is oriented parallel to the plane of transportation. The effect is supported by an impact plate which is oriented parallel to the plane of transportation. The air stream generates a partial vacuum in the plane of transportation, and the front edge and the material web are drawn in the direction of the stationary blade (Venturi effect). At the same time, the product is moved in the direction of transportation by the air stream. This makes it possible to feed the front edge of the material web or of a product which is to be transported onward in the direction of transportation into a following transportation system.
It is particularly preferred if the blown air changes its direction during a processing cycle in order to support the outputting of a cut-out portion. Its direction is therefore preferably changed in such a way that as the cut-out portion to be separated approaches the direction of said blown air points onto the plane of transportation and deflects the front edge of the cut-out portion in the direction of the rotational element. The front edge can then be additionally secured to the rotational element by suction air, as described above.
An example of the invention is illustrated in the drawings and described below. In said drawing, in purely schematic views:
The cross cutting units 10, 20 each have stationary blades 12, 22 which are arranged in a first or second stationary blade block 11, 21 above the plane E of transportation. The material web is moved in the direction T of transportation with a material web transportation means (not shown here). Underneath the plane E of transportation of the material web 30 there are preferably cylindrical first or second rotational elements 14, 24 which can be rotated about a rotational axis D1, D2 which is oriented parallel to the plane of transportation and transversely with respect to the direction T of transportation, and each have a blade 16, 26 which is permanently attached to the rotational element 14, 24 and therefore rotates with it. As a result of rotation of the rotational element 14, 24, the rotating blades 16, 26 are moved past the stationary blades 12, 22. The stationary and rotating blades 12/16, 22/26 of a cross cutting unit 10, 20 are preferably arranged in a slightly staggered fashion with respect to one another so that point contact which migrates transversely with respect to the direction of transportation, and therefore a precise cut, are brought about here.
In the present case, both rotational elements 14, 24 are arranged underneath the plane E of transportation. As a result, the blade position can be set satisfactorily, the device can be satisfactorily serviced and the cut-out portion 34 to be produced can easily be carried downward. Other arrangements, for example both rotational elements 14, 24 at the top or one at the bottom and one at the top, are likewise possible.
The two rotational elements 14, 24 are preferably actuated and driven by two independent servo drives (not illustrated here). In order to cut with precise register, register marks on the material web 30 are generally used. The inputting of the desired lengths d1, d2 of the cut-out portion 34 and of the product 38 in a control unit (not shown here) allows the rotational elements 14, 24 to be correctly positioned automatically. The drive of the first cross cutting device 10 or of the first rotational element 14 reacts with positive or negative accelerations to changes in the distances between the register marks. The drive of the second cross cutting device 20 or of the second rotational element 24 follows said accelerations in a corresponding way.
The first cross cutting unit 10 is of an essentially conventional design. Differences from the prior art are the stationary blade block 11 in a blown air system, further details on which blade block 11 are given below.
The second cross cutting unit 20 has, in the second rotational element 24, three suction air zones 60, 62, 64 to which suction air can be applied individually or in combination, i.e. can be connected individually or in combination at specific times during the processing cycle to a vacuum or suction air source (not shown here). The suction air zones 60, 62, 64 are arranged on the circumferential face 25 of the second rotational element 24, a first suction air zone 60 being arranged directly in front of the rotating blade 26 in the direction of rotation (here in the counterclockwise direction), and the further suction air zones 62, 64 being located in front of it in the direction of rotation. The three suction air zones 60, 62, 64 take up in total approximately a quarter of the circumferential face of the second rotational element 24 and each extend over an arc corresponding to an angle of approximately 30°. Depending on the length of the cut-out portions 34 to be separated, it is possible also to provide fewer or more and/or shorter or longer suction air zones 60, 62, 64. Here there is no subdivision transversely with respect to the direction of transportation but it is possible to provide one in order to also adapt the system to material webs of different widths.
A blown air zone 70 is located at a small angular distance of approximately 10-30° behind the rotating blade 26 in the direction of rotation. Said blown air zone 70 has here a length corresponding to an angle of approximately 60°.
Each of the zones 60, 62, 64, 70 is assigned in each case a chamber (not illustrated here) in the interior of the second rotational element 24, said chamber being connected to in each case one entry 66, 67, 68, 72. The chambers are each covered with an air-permeable cover element which forms in each case one zone 60, 62, 64, 70. The cover element is, for example, a plate with bores or preferably an air-permeable, porous aluminum element. The latter provides a particularly homogeneous suction effect. The entries 66, 67, 68, 72 are arranged in the end face 28 of the second rotational element 24 and therefore rotate with the rotational element 24. They can be closed or opened individually or in combination by a control cam 112, which also makes the rotating movement. Since the entries 66, 67, 68, 72 are moved past the fixed connecting element 120, arranged in the region of the rotational axis D2, for suction air and blown air, the chambers and the assigned zones 60, 62, 64, 70 each have suction air or blown air applied to them depending on the position of the rotational element 24. The selection of the zones and their function during a processing cycle is described in more detail below in conjunction with
Downstream of the cross cutting units 10, 20 in the direction T of transportation there is in each case a transportation system 40 or 50. Both transportation systems 40, 50 are of similar design and have at least one pair of driven transportation rollers 42 and 52 as well as upper and lower guide elements 44 and 54. The transportation systems 40, 50 preferably have a drive which is independent of the material web drive (not illustrated here) with which the material web 30 is fed to the cross cutting device. The material web or a product running in front can thus preferably be accelerated with respect to the material web 30 running behind after a first separating cut 130 has been carried out by forming a gap 36.
The guide elements 44, 54 move the approaching front edge 32 of the material web 30 or of a product 38 into the region of the transportation rollers 42, 52. This function is supported by blown air systems in the stationary blade blocks 11, 21. As is illustrated in more detail in
However, in the second cross cutting unit 20 only the front edge 32 of the product 38 is to be moved onward in the direction T of transportation. The front edge of the cut-out portion 34 is to be moved off downward through the rotational element 24. In order to support this, the second blade block 21 has a second blown air duct 82 which can also be connected to the entry 80 and points essentially perpendicularly onto the plane E of transportation. The blown air is alternately fed to the ducts 81 and 82, the front edge and the part of the material web 30 which follows it being correspondingly deflected upward or downward. The mechanism for adjusting the air stream is described in more detail below with reference to
At least in the second cross cutting unit 20, in each case a plurality of first (“Venturi”) or second ducts 81, 82 are preferably provided transversely with respect to the direction T of transportation, said ducts 81, 82 alternating with one another, each opening along a line transverse with respect to the direction of transportation and each forming a blown air strip, which is explained in more detail with respect to
In the next step (shown in
In the next step which is shown in
In the next step shown in
If format lengths of the order of magnitude of the circumferential length of the rotational elements 14, 24, or more, are to be manufactured given a material web 30 which is transported at a constant speed, one or both rotational elements 14, 24 can be driven asynchronously with a variable speed. After the cut, the corresponding rotational element is braked again to such an extent that the desired format length runs through before a further separating cut is made.
Depending on the length d1 of the cut-out portion 34, one, two or three of the suction zones 60, 62, 64 or the corresponding entries 66, 67, 68 are cleared by the control device so that, depending on the position of the second rotational element 24, it is possible to apply suction air to them. The clearing of the suction zones 60, 62, 64 can be carried out automatically by means of the control unit or manually, and is described in more detail below with reference to
After the step shown in
As
As is shown in
A situation which corresponds essentially to
During operation, the rotational element 24 including the control cam 110 and the cover plate 116 rotates past a fixed connecting element 120 for blown air and suction air. The connecting element 120 has two kidney-shaped milled elements 122, 124, the upper one of which has suction air/vacuum applied to it and the lower has blown air applied to it. The milled element 122 for suction air is located approximately above the horizontal and the milled element 124 for blown air is located below the horizontal. The position of the milled elements 122, 124 is matched to the position of the entries 66, 67, 68, 72 in such a way that suction air and the blown air are applied to the suction air and the blown air zones at the desired times within the processing cycle.
In order to switch the desired number of suction zones 60, 62, 64 on and off during the setting up process, the control cam 110 is rotated in relation to the rotational element 24, while the cover plate 116 remains fixed in relation to the rotational element 24. The control cam 110 preferably has latched positions which are defined with respect thereto. The control cam 110 can be adjusted manually but also automatically. Its position can preferably be changed during operation so that when format changes occur it is not necessary to stop and restart.
In order to carry out the adjustment automatically, the control cam 110 has a cam 113 in particular also on both cylinder shaft ends 29. A latch 115 can be moved under remote control into the orbit of the cam 113. The second rotational element 24 makes at least one rotation for the adjustment and moves into a defined basic position in which the control cam 110 is in a defined position. Further rotation of the rotational element 24 through a specific angle causes the control cam 110 to be adjusted and allows the desired combination of entries 66, 67, 68, 72 to be cleared or closed. After adjustment has been carried out, the latch 115 is removed from the orbit of the cam 113 so that there is no further adjustment of the entries during the normal operating mode.
A control tube 84 is rotatably mounted at both ends of the stationary tube 83 and connected to a toothed belt 102. The blown air is introduced here into the control tube 84 from both sides of the blade block 21 but it can also only come from one side. On its circumference the control tube 84 has groups of continuous bores 85, 86. These are at the same axial distance from one another as the air slits 87, 88. However, they are offset with respect to one another in the radial direction. The air slits 87 lead to the first blown air ducts 81 which are located one next to the other in the transverse direction. The air slits 88 lead to the second blown air ducts 82 which are located one next to the other in the transverse direction but are offset with respect to the first blown air ducts 81. The second blown air ducts 82 open in front of the first blown air ducts 81 in the direction of transportation. By rotating the control tube 84, either the bores 85 of the first group are made to overlap with the air slits 87, or the bores 86 of the second group are made to overlap with the air slits 88. As a result, depending on the position of the control tube 84, the Venturi blown air or normal blown air is switched on. The time of switching over can be matched in an optimum way to the time of the separating cut 132 by means of the 1:1 transmission ratio by virtue of the toothed belt 102.
If a clocked Venturi controller is not required, manual adjustment can alternatively be provided. A control tube with corresponding air slits can be adjusted manually in such a way that the Venturi blown air strip or the normal blown air is switched on, or both are switched on together.
Although the invention has been described in detail and with reference to the specific embodiments thereof, it would be apparent to those skilled in the art that various changes, arrangements and modifications may be applied therein without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 06 005 836.9 | Mar 2006 | EP | regional |
