This application claims priority from German Application No. 10 2008 060 394.5, filed on Dec. 3, 2008, the disclosure of which is incorporated herein by reference in its entirety.
The invention concerns an apparatus for forming a stream of overlapping sheets or stacks of sheets, comprising a first transport device for delivering overlap-free sheets or stacks of sheets at a speed v1, a second transport device for carrying away the stream of overlapping sheets or stacks of sheets at a speed v2, and a device for decelerating the sheets or stacks of sheets from v1 to v2. Furthermore, the invention concerns a method for forming a stream of overlapping sheets or stacks of sheets, comprising the steps of: delivering overlap-free sheets or stacks of sheets on a first transport device at a speed of transport v1, decelerating the incoming sheets or stacks of sheets by means of a device for decelerating from the speed of transport v1 to a speed of transport v2 of the outgoing sheets or stacks of sheets, forwarding the sheets or stacks of sheets to a second transport device, and carrying away the stream formed from overlapping sheets or stacks of sheets on the second transport device at the speed of transport v2.
In the paper-processing industry, it is normal to separate individual sheets e.g. from paper webs (or cardboard webs) by at least one of longitudinal or transverse cutting, then assembling them as individual sheets or stacks of sheets into an imbricated or overlapping stream. In order to form the stream from overlapping sheets or stacks of sheets, the individual sheets or stacks of sheets are decelerated from a first (input) speed v1 to a second (output) speed v2. For this purpose, a corresponding device for decelerating the sheets or stacks of sheets is provided between two transport devices. The sheet or stack of sheets, which is located in the region of the decelerating device, is decelerated in the process, while a subsequent sheet or stack of sheets is still being conveyed at the input speed v1. As a result the leading edge of the subsequent sheet/stack of sheets slides over the trailing edge of the sheet/stack of sheets which is just decelerating and leads to overlapping. Naturally, the sheets or stacks of sheets subjected to a stacking or overlapping process can be films or other sheet-like products.
Various apparatuses and methods for forming a stream of overlapping sheets or stacks of sheets are known. In U.S. Pat. No. 3,336,028, for example, an apparatus is disclosed comprising a first transport device including an upper belt and a lower belt for delivering separated sheets or stacks of sheets. The second transport device for carrying them away includes a lower belt, the upper belt of the first transport device extending into the region of the second transport device. To form the device for decelerating the sheets or stacks of sheets, the lower belt of the second transport device is wrapped around a drum unit. The perforated lower belt of the transport device wraps around a drum which has openings and is connected to a vacuum unit for forming a suction drum. Inside the drum is arranged a pipe which has two diametrically opposed openings. Like the drum, the pipe is designed to be movable. Inside the pipe is arranged a stationary pipe which has a slot. The slot is directed onto the region of transfer of the sheets or stacks of sheets from the first transport device, and is opened or closed by at least one of the pipe or drum in phases/alternately.
German Patent Document DE 30 10 284 A1 is also concerned with an apparatus for conveying and overlapping sheets or sheet stacks. This apparatus comprises an upper belt extending over the whole length and two lower belts of which one lower belt is designed and arranged as a transport device for delivering sheets or stacks of sheets, and the other lower belt is designed and arranged for carrying away the overlapping sheets or stacks of sheets. Between the lower belts are arranged guide rollers. The rear lower belt is designed as an endless decelerating suction belt and has, between the upper and lower runs, a suction box in which is arranged a rotating suction pipe which is provided with an opening.
The known apparatuses and methods have the drawback that the rotating elements rotate at a constant speed and the circumferential speeds of drum and pipe or suction pipe are merely adapted only to the paper format to be processed. This means that the transport devices on the one hand and the decelerating device on the other hand have different speeds. Hence a relative speed arises between the sheets or stacks of sheets and the decelerating device. As a result, deceleration and the accompanying overlapping of the sheets or stacks of sheets is inadequate and imprecise, particularly at high speeds. It might also be said that energy is destroyed suddenly by the different speeds of the sheets or stacks of sheets on “impact” of the sheets or stacks of sheets on the transport device provided for carrying them away, leading to imprecise transfer. The imprecision of overlap is further reinforced by the fact that, during deceleration, support from above is required, that is, a decelerating action on the sheets or stacks of sheets is required on both sides, and there is only indirect contact between the decelerating device and the sheets or stacks of sheets. A further drawback of known apparatuses is that the apparatuses are structurally elaborate, which among other things, makes it difficult to exchange parts during maintenance or repair.
It is therefore an object of the invention to provide a simple and reliable apparatus for forming a stream of overlapping sheets or stacks of sheets, by means of which precise overlapping of the sheets or stacks of sheets can be carried out. It is further an object of the invention to provide a corresponding method.
The above and other objects are accomplished according to one aspect of the invention wherein there is provided an apparatus for forming a stream of overlapping sheets or stacks of sheets which, according to one embodiment, comprises a first transport device to deliver overlap-free sheets or stacks of sheets at a speed v1 along a plane of transport EV, a second transport device to carry away the sheets or stacks of sheets at a speed v2 along a plane of transport EH, and a decelerating device arranged to receive the sheets or stacks of sheets at the speed v1 from the first transport device, decelerate the sheets or stacks of sheets to the speed v2 and deliver the decelerated sheets or stacks of sheets to the second transport device to form the stream of overlapping sheets or stacks of sheets, wherein the decelerating device comprises a suction roller unit is actuated independently of the transport devices, and wherein the suction roller unit comprises a stationary element and an unevenly driven movable element.
The uneven driving of the movable element means that the movable element can be decelerated and accelerated, that is, operated at different speeds during the deceleration process, so that the sheets or stacks of sheets may be taken over and discharged without slipping and without relative movement in relation to the decelerating device. This guarantees precise overlapping of the sheets or stacks of sheets. Separation of the components of transport devices on the one hand and decelerating device on the other hand makes it easier to transfer the sheets or stacks of sheets to form a stream of overlapping sheets or stacks of sheets, and allows easy exchange or easy maintenance of component parts of the apparatus.
In an embodiment of the invention the movable element may be a rotatably drivable cylindrical outer ring in which a stationary vacuum unit is arranged as the stationary element. With this design, precise pick-up, deceleration and discharge of the sheets or stacks of sheets into a stream of overlapping sheets or stacks of sheets is further improved by the fact that the speed of rotation of the rotating element is controllable with particular precision.
In a further embodiment of the invention, the outer ring and the vacuum unit may be constructed and designed to correspond to each other to form at least one optionally closable or openable suction opening. In other words, both the outer ring and the vacuum unit may have at least one opening which can either be brought into register by the relative movement between outer ring and vacuum unit to form the suction opening for drawing in the sheets or stacks of sheets, or close the suction opening when the openings are staggered. Thus reliable suction of the sheets or stacks of sheets can be carried out very precisely and rapidly.
In another embodiment, the movable element of the suction roller unit may be in direct contact with the sheets or stacks of sheets during deceleration, with the result that handling of the sheets or stacks of sheets and the precision of placement or take-over and discharge of the sheets or stacks of sheets are improved.
According to a further embodiment of the invention, the suction roller unit may be constructed and designed for application of the decelerating force to the sheets or stacks of sheets on one side only. In other words, the suction roller unit may engage the sheets or stacks of sheets only from below, dispensing with additional mechanical or otherwise operating elements from above, so that e.g. at least one of coated sheets, printed sheets, or stacks of sheets can be transported and formed into a stream of overlapping sheets or stacks of sheets.
Additionally, in another embodiment the speed of rotation of the movable element of the suction roller unit may be controlled individually. This means that the speed of rotation may be varied at least one of during a single revolution, from one sheet to the next, or from one stack of sheets to the next, which allows easy and rapid adaptation of the apparatus e.g. when changing format, that is, when changing the sheet size.
According to another aspect of the invention, there is provided a method for forming a stream of overlapping sheets or stacks of sheets, comprising, according to an embodiment, comprising delivering overlap-free sheets or stacks of sheets on a first transport device at a speed of transport v1 in a first plane of transport EV, driving a suction roller unit initially at the speed of rotation v1, collecting the sheets or stacks of sheets at speed v1 from the first transport unit by fixing the sheets or stack of sheets to the suction roller unit while rotating at the initial speed of rotation v1, decelerating the suction roller unit to speed a speed v2 after collecting the sheets or stacks of sheets, discharging decelerated sheets or stacks of sheets to a second transport device at the speed v2 and in a second plane of transport EH, accelerating the suction roller unit back to speed v1 after discharge of the sheets or stacks of sheets, collecting subsequent sheets or stacks of sheets after acceleration of the suction roller unit back to speed v1 and discharging the subsequent sheets at the speed v2 to the second transport device to form the stream of overlapping sheets or stacks of sheets, and carrying away the stream of overlapping sheets or stacks of sheets on the second transport device at the speed of transport v2.
The present invention will be more readily understood from the following detailed description when read in conjunction with the accompanying drawings, in which:
The apparatuses shown in the drawings and described in more detail below serve to form an imbricated stream of sheets or stacks of sheets of paper or cardboard. Naturally, the apparatuses are also suitable for forming an imbricated stream of sheets or stacks of sheets of film or the like as well as for stacking.
A first embodiment of the apparatus 10 according to the invention is shown in
The device 14 for decelerating the sheets or stacks of sheets is designed as a suction roller unit and is independent of the transport devices 12, 13. This means that the device 14 is a separate unit which is operatively connected to the transport devices 12, 13, but can be actuated independently of them. The device 14 comprises a stationary element 15 and a movable element 16. The movable element 16 is assigned a drive 17 (see
In an embodiment of the invention as in
The two transport devices 12, 13 are arranged one behind the other in the direction of transport T of the sheets or stacks of sheets. The two transport devices 12, 13 have a gap between them in the (working) region of which the device 14 is arranged. The transport device 13 which is downstream in the direction of transport T may offset downwards from the upstream transport device 12, so that the sheets or stacks of sheets pass in stages, as it were, from the upstream transport device 12 via the device 14 to the downstream transport device 13. As can be seen e.g. from
As can be seen from the figures in all the embodiments, the device 14, namely the suction roller unit, is constructed and designed for applying the deceleration force to the sheets or stacks of sheets on one side only. In other words, the device 14 acts exclusively from below, so that the sheets or stacks of sheets are drawn in from below and decelerated by reduction of the speed of rotation vR of the suction roller unit or, to be more precise, of the movable element 16. The speed of rotation vR of the movable element 16 (in this embodiment the outer ring) can be controlled individually. For this purpose each drive 17 is connected to a control means by means of which the speed of rotation vR is adjustable in particular in dependence of the speeds of transport v1 and v2, the number and positioning of the openings 19, 20 or suction opening 21, and the format of the sheets.
Optionally the second transport device 13 which is downstream in the direction of transport T can be assigned an additional suction unit 22. This suction unit 22 is arranged so the stream 11 of overlapping sheets or stacks of sheets is fixed or guided reliably. In other words, the suction unit 22 prevents the slipping of sheets or stacks of sheets on the transport device 13. In the region of the first transport device 12, which is upstream in the direction of transport T, can be arranged an electrostatically operating element 23 for interlocking incoming stacks of sheets. An ionisation device of this kind serves to interlock several sheets forming a stack of sheets for transport within the apparatus 10 and deceleration to form the stream 11 of overlapping stacks of sheets. The element can be constructed in one or more parts and at least one of arranged above or below the transport device 12.
The first transport device 12 which is upstream in the direction of transport T comprises a lower belt 24 and an upper belt 25. Both belts are endlessly rotating belts, chains or the like and are guided about at least one of driving or deflecting rollers 26 or 27. The second transport device 13 which is downstream in the direction of transport T has only a lower belt 28 which, like the belts of the transport device 12, can be an endlessly rotating belt, a chain or the like and is guided about at least one of driving or deflecting rollers 29. The lower belts 24 and 28 and the upper belt 25 can also be formed from several belt strips which are spaced apart from each other. The upper belt 25 of the transport device 12 can vary in particular in length and positioning. This means that the upper belt 25 may protrude slightly beyond the lower belt 24 e.g. in the direction of transport T according to
The apparatus 10 in the second embodiment according to
Below, the principle of the method is described in more detail with the aid of the attached figures.
Individual sheets or stacks of sheets, e.g. of at least one of transversely or longitudinally cut paper or cardboard, are conveyed on the transport device 12 in the direction of transport T, this being at speed v1. The sheets or stacks of sheets, which lie without overlap on the transport device 12, enter the region of the decelerating device 14 and are decelerated by the device 14 from the speed of transport v1 to a speed of transport v2. Deceleration takes place with the apparatus 10 according to
The sheets or stacks of sheets are still held by the suction roller unit at their downstream, trailing end, while the leading end is already on the transport device 13. During deceleration, the subsequent sheet or stack of sheets which is still being conveyed at speed v1 is slid over the decelerating sheet or stack of sheets. As soon as the opening 20 in the outer ring no longer corresponds to the opening 19 in the vacuum unit, that is, is no longer in register, the suction process ends because the suction opening 21 is closed, and the sheets or stacks of sheets are carried away by the transport device 13 at speed of transport v2. Immediately after closure of the suction opening 21, by further rotation of the outer ring the latter is accelerated in order to collect the next sheet or stack of sheets. In the process the outer ring is accelerated at the angle of acceleration β back to the speed of transport v1 until vR corresponds to v1, so that the subsequent sheet or stack of sheets is caught in the same position as the preceding sheet or stack of sheets.
On collection and during deceleration of the sheets or stacks of sheets, the sheets or stacks of sheets abut directly against the suction roller unit and, to be more precise, in particular also against the outer ring. In this case, the deceleration force acts exclusively from below. In other words, the sheets or stacks of sheets are drawn in exclusively from one side, namely from below, during collection and deceleration. In the embodiment according to
The apparatus according to
Other procedures are possible, for example when the movable element 16 has several openings 20 (see
It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and rage of equivalents of the appended claims.
Number | Date | Country | Kind |
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10 2008 060 394.5 | Dec 2008 | DE | national |