Abstract:
An assembly for moving paper, board and cellulosic web rolls in a roll packaging system includes a plurality of roll handling stations incorporating at least one receiving station for the entry of rolls into the system, one wrapping station for winding at least one wrapper course on the periphery of the rolls, and at least one other station, and an indexing conveyor having a car for moving the rolls which is adapted to move synchronously into positions coinciding with each one of said roll handling stations. The car of the indexing conveyor is adapted to move on at least three different elevation levels named as a base elevation level  0 , a first elevation level and a second elevation level. Additionally, at least a portion of the car coinciding with one station is on an elevated level in regard to the other parts of the car coinciding with the other stations.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a method for transferring rolls of paper, board and cellulosic web in a roll packaging system during wrapper winding, label attachment and header placement. 
   The invention also relates to an assembly for implementing the method. 
   The papermaking industry generally uses a packaging method wherein inner headers are first placed on the ends of a roll to be packaged, next a wrapper is wound about the roll and finally the outer headers are placed on the roll ends. The packaging cycle and system themselves can be implemented in different ways and, typically, the packaging system is tailored to the needs of the mill. Inasmuch as the roll widths vary in a wide range, the wrapping method of the roll wrapper must be selected to meet the wrapping capacity needs. If an extremely high packaging capacity is required, wrapping stations can be used equipped with plural wrapper rolls of different widths of which a suitable wrapper can be selected for any roll to be packaged. However, this kind of wrapping station is very costly, whereby within the capacity limits of the station it may be more cost-advantageous to use, e.g., wrapping by overlapping layers, whereby two or more parallel wrapper courses are wound about the perimeter of the web roll. This kind of wrapping technique can be implemented using one or two wrapper widths thus allowing a very simple station layout. A disadvantage herein, however, is that either the roll being wrapped or the wrapping station itself must be moved during wrapping so as to allow the parallel wrapper courses to be wound. 
   In the above-mentioned overlap wrapping, the paper, board or cellulosic web rolls to be packaged are wrapped using a wrapper narrower than the roll to be wrapped. As the wrapper width is not sufficient to cover the entire perimeter width of the web roll, the roll is packaged by winding plural parallel wrapper turns thereabout. For such parallel overlap wrapping on a web roll, either the roll or the wrapper car must be moved parallel to the longitudinal axis of the roll. One technique of implementing the roll transfer is to move the roll being packaged on the cars of an indexing conveyor. The indexing conveyor has separate stations for each packaging step: roll entry, buffer, wrapping, labeling and placement of outer headers, whereby one indexing conveyor car is located at each one of the stations. The car or cars are reciprocatingly moved between the stations so that after a car has moved a roll to the next station, the car is returned to its “home” position to be ready to receive a new roll to be transferred. To move the rolls forward, the indexing conveyor of the car(s) is moved upward, whereby the rolls thereon are elevated from the support rollers or support means of the station. As the car of the conveyor system has an integrated construction or, alternatively, the indexing car conveyor is comprised of cars connected together and moving in synchronism, all rolls are moved simultaneously. A roll transferred in this kind of system to the wrapping station is positioned by the movements of the indexing conveyor. Such a positioning of the web rolls at the wrapping station is unproblematic provided that the wrapper rolls with their feed assemblies are adapted movable at the wrapping station. However, if the wrapping station structures are stationary, lateral transfer of the roll at the wrapping station causes substantial time loss in overlap wrapping. Namely, the roll must be moved laterally in the direction of its longitudinal axis for winding the adjacent wrapper courses. Herein, an indexing conveyor is obviously problematic, because it forces all of the web rolls to move at the transfer of web roll being wrapped. Hence, after the completion of overlap wrapping of a roll, all the other rolls must be relocated back to their center positions at their respective stations by the movements of the indexing conveyor, which is a retarding step in the cycle time. While this may not necessarily drawback if only a small number of rolls are to be overlap wrapped, the roll sizes vary widely in modern papermaking mills, whereby the transfer movements of the indexing conveyor may give rise to a substantial reduction of available packaging capacity. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a method offering an improvement to the operating speed of a packaging system using an indexing conveyor. 
   The goal of the invention is attained by arranging the loading surface of at least one car at a given station, e.g., the car positioned at the wrapping station, to a level above the loading surface elevations of the other cars and, further, adapting the indexing conveyor to operate using at least three different elevation levels. 
   The invention provides significant benefits. 
   By virtue of the invention, the operating speed of a packaging system in the overlap wrapping of rolls can be increased with extremely simple arrangements. A separate center positioning of rolls after the completion of the overlap wrapping step of a roll becomes redundant, whereby the overlap-wrapping-related lengthening of cycle time remains as minimal as the cumulative wrapping time due to the winding of the two or three adjacent wrappers. Inasmuch as the positions of rolls at other stations than the wrapping station remains stationary, the positioning of the other rolls remains accurately at the set coordinates. The mechanical constructions required in the implementation of the invention are uncomplicated and require only actuators capable of driving the conveyor cars to three different elevation levels. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS  
     In the following, the invention is examined in more detail with the help of the appended drawings in which 
       FIG. 1  shows a side elevation view of a construction according to the invention; 
       FIG. 2  shows an embodiment of a receiving station; 
       FIG. 3  schematically shows a top view of an assembly according to the invention in its first operating stage; 
       FIG. 4  schematically shows a top view of the assembly according to the invention in its second operating stage; 
       FIG. 5  schematically shows a top view of the assembly according to the invention in its third operating stage; 
       FIG. 6  schematically shows a top view of the assembly according to the invention in its fourth operating stage; 
       FIG. 7  schematically shows a top view of the assembly according to the invention in its fifth operating stage; 
       FIG. 8  schematically shows a top view of the assembly according to the invention in its sixth operating stage; 
       FIG. 9  schematically shows a top view of the assembly according to the invention in its seventh operating stage; 
       FIG. 10  schematically shows a top view of the assembly according to the invention in its eighth operating stage; 
       FIG. 11  schematically shows a top view of the assembly according to the invention in its ninth operating stage; 
       FIG. 12  schematically a top view of the assembly according to the invention in its tenth operating stage; 
       FIG. 13  schematically a top view of the assembly according to the invention in its eleventh operating stage; 
       FIG. 14  schematically a top view of the assembly according to the invention in its twelfth operating stage; 
       FIG. 15  schematically shows a top view of the assembly according to the invention in its thirteenth operating stage; 
       FIG. 16  schematically shows a top view of the assembly according to the invention in its fourteenth operating stage; and 
       FIG. 17  schematically shows a top view of the assembly according to the invention in its fifteenth operating stage. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
   Referring to  FIG. 1 , therein is illustrated the multiple elevation principle of the invention. A car  4  of an indexing conveyor is adapted adjustable at three different heights later in the text called elevation levels. Along the length of one car  4  of the indexing conveyor are situated five packaging system stations: receiving station  5 , buffer station  6 , wrapping station  7 , labeling station  8  and header placement/roll ejection station  9 . The lowest elevation level  0  is the so-called base level on which rolls being handled at the receiving station  5  can be moved with the other rolls staying stationary. At the first elevation level  1 , the roll located at the wrapping station may be moved with all the other rolls staying stationary and, at the second elevation level  2 , all the rolls are elevated to the car  4  of the indexing conveyor, whereby they move synchronously. If a roll happens to be at the receiving station, it will move along with the transfer of the roll residing at the first elevation level. 
   At the receiving station  5 , a roll to be placed on the conveyor is positioned differently depending on whether the roll shall be wrapped into a single wrapper or whether it needs overlap wrapping, whereby plural adjacent wrapper courses must be wound thereon. For this position operation, the receiving station  5  is provided with a parallelogram mechanism suited to elevate and lower the roll in regard to the car  4  of the indexing conveyor. Respectively, the wrapping station  7  must have equivalent means for moving one roll without simultaneously causing uncontrolled movement of other rolls. To this end, the top level of the car  4  is elevated at the wrapping station to a higher position in regard to the car top level elevation at the other stations. Additionally, each station is provided with support rollers or support means on which the rolls can be lowered in situations requiring the car  4  of the indexing conveyor to be moved, e.g., during the return movement of car  4 , without disturbing the positions of the other rolls. The positioning of the rolls at the stations can be performed in either a centered or offset fashion. In the present text, centered positioning refers to a roll position having its center point in the lateral dimension of the roll being aligned with the centerline of the station, while offset positioning refers to any roll position having the roll center point shifted into an offset position from the centered position. 
   Next, the invention is discussed in greater detail with the help of  FIGS. 3-18 . This sequence of diagrams illustrates the travel of a wide roll in the packaging system as the roll is being wrapped using three-wide overlap wrapping. In  FIG. 3 , a roll  10  to be taken to overlap wrapping is shown entering the receiving station  5  of the centering station  18 . Preceding the roll to be overlap wrapped, other rolls to be single-wrapper packaged are entering the receiving station, namely: roll  10 , roll  12  at the buffer station  6  situated downstream from the receiving station  5 , roll  13  at the wrapping station  7 , roll  14  at the labeling station  8  and roll  15  at the pressing station  9  waiting for the placement of the roll headers. During the following step, a roll  11  is taken to the buffer station  5 , wherein the roll position is centered. Next, the car  4  of the indexing conveyor is elevated by two level shifts, whereby rolls at all stations are raised upward thus allowing the rolls to be moved forward. After the movement of car  4  in the indexing conveyor has been completed, the situation is as shown in  FIG. 4 , where the receiving station  5  is empty and the other stations have rolls  11 - 14  to be packaged in a single wrapper waiting in a centered position. The receiving station  5  is shown ready for the entry of roll  10  to be overlap wrapped. The roll  10  to be overlap wrapped is still at the centering station, where it is positioned in regard to its longitudinal direction so that the roll can be lowered into the proper position on the car of the indexing conveyor. This centering step is necessary to guarantee correct positioning of the roll at the packaging stations. When a roll to be overlap wrapped enters the receiving station, the supporting means of the roll are driven to their lower positions and the roll to be overlap wrapped is lowered directly onto the car  4  of the indexing conveyor. This situation is shown in  FIG. 5 . As the car  4  of the indexing conveyor is at the base elevation level, that is, in its lowest position, the roll situated at the receiving station  5  can be moved. The roll  10  to be overlap wrapped is next moved by the indexing conveyor into a position, wherein the roll enters correctly located for wrapping: the roll is moved backward so that the roll entering the wrapping station  7  has its end properly positioned in regard to the wrapper edge for winding the first wrapper course. This situation is shown in  FIG. 6 . 
   Next, the car of the indexing conveyor is raised by two steps to the second elevation level  2 , whereby all rolls  10 - 13  located at stations  5 - 8  are elevated upward with the exception of roll  14  situated at the pressing station  9  for attachment of roll headers. At this moment, the roll  14  residing at the pressing station must be ejected or the pressing station must already be empty. Next, the car  4  of the indexing conveyor is transferred forward, whereby all the rolls resting on the indexing conveyor are transferred forward. After the transfer step, rolls  10 - 13  are lowered onto their support means and the car of the indexing conveyor is moved backward. At this moment, the roll  10  to be overlap wrapped is situated in an offset position at the buffer station  6  and the other rolls  11 - 13  are in centered positions at their respective stations. This sequence leaves the conveyor in the situation of  FIG. 7 . Thereafter, to the receiving station  5  is loaded the next roll  16  that is positioned centrally, whereby the situation of  FIG. 8  results. After elevating the car of the indexing conveyor by two stages to the second elevation level  2  and transferring the car  4  one step forward, the situation of  FIG. 9  is attained, wherein the roll  10  to be overlap wrapped is correctly positioned at the wrapping station  7  for winding the first wrapper course thereon. Subsequent to winding the first wrapper, the car  4  of the indexing conveyor is elevated by one step to the first elevation level  1 , whereby roll  10  residing at the wrapping station  7  rises upward and, if the car of the indexing conveyor has another roll loaded thereon at the receiving station, also the latter roll is moved up, however, without any change in its positioning. Next, the roll  10  to be overlap wrapped is moved forward for winding the second wrapper course. Subsequent to the second wrapping, the roll  10  is once more transferred on the first elevation level of the car to the station performing the third wrapping. Simultaneously, a new roll  17  is taken to the buffer station. This situation is shown in  FIG. 12 . Next, roll  17  taken to the receiving station is transferred at the base elevation level forward into an offset position such that when roll  10  residing at the wrapping station  7  is transferred into a centered position moving the roll at the first elevation level  1  backward, also roll  17  residing at the receiving station  5  is moved backward into a centered position. Having the support means of the receiving station  5  driven into their lower position, also rolls  17 ,  10  residing at the receiving and wrapping stations are elevated upward while the other rolls remain resting on their support means. This situation is shown in  FIG. 14 . Hereupon, the indexed forward transfer of the rolls can be continued at elevation level  2 , whereby all the rolls move in synchronism. The above-described cycle is reinitiated when a roll to be overlap wrapped enters the receiving station  5 . 
   The receiving station can be equipped with a loading/elevating apparatus based on a parallelogram mechanism such as is disclosed in Canadian patent no. 2,003,605. If the capacity need is not excessively high requiring the maximally fast operating speed, the arrangement shown in  FIG. 2  may be used. Herein, the roll is manipulated by means of a top-side receiver comprising a frame  18  and a receiver arm  19 . The arm  19  serves to retard the motion of the roll and stop the roll on the car of the indexing conveyor. When the car  4  of the indexing conveyor must be moved without disturbing the positioning of the roll, the receiver arm can be actuated to unload the roll from the car and reload it back onto the car after the movement thereof is at a standstill. Thus, this arrangement provides the same function as a loading/unloading apparatus. The position of the arm may be monitored by means of an absolute position sensor, whereby a roll entering a station can be positioned accurately beside the indexing conveyor. Then, lowering the roll onto the car needs only a minimal transfer movement resulting in a short cycle time increment. Roll diameter and position sensor signals must be available for roll positioning. Based on this information, the roll position at the side of the can be computed. Obviously, a bottom-side receiver can be used in lieu of the top-side receiver. 
   In the above text, a system has been described comprising five separate roll handling stations. Obviously, the number of roll handling stations can be varied according to the number of roll packaging and handling stages required in the system. However, the minimum system layout capable of implementing the method according to the invention comprises at least a receiving station, some other station and a wrapping station. The number of stations following the wrapping station is unessential to the implementation of the invention inasmuch as the rolls leave the wrapping station in a centered position. If the number of stations is only two, the arrangement according to the invention is unnecessary. While the offsetting transfer of rolls required at the stations may be carried out at any station preceding the wrapping station, in practice this step is most advantageously carried out at the receiving station. The car of the wrapping station can be a single, contiguous car or, alternatively, it may comprise a number of connected and thus jointly moving separate cars. A roll to be overlap wrapped may be offset positioned already at the centering station  18  preceding the receiving station. Then, no offset movement is needed at the buffer station, but instead, the roll can be loaded at the base level  0  directly onto the car and no movement of the car is required for offset positioning of the roll. However, offset prepositioning of the roll can be carried out at any station when the conveyor is operating at its base level  0 . Alternatively, the roll may be taken to the wrapping station ready centered, whereby the roll end is positioned at the wrapping station for the first wrapping stage before starting wrapping. The operating strategy is selected so that the system gives sufficient and optimal packaging capacity in a particular operating environment. The elevated portion of the car may also be situated elsewhere than at the wrapping station if a need arises at some other station to move the rolls in their longitudinal direction. In certain cases, narrow rolls must be transferred during labeling if multiple labels must be attached at their center line.