Abstract:
An apparatus for the opening of paper bobbins and other rolls of material is provided. A flat blade is advanced from the side of a wound roll of material such that it intersects the roll over substantially its entire width. A cutting blade or other cutting mechanism then severs the layers of the roll which are outside the flat blade, and the flat blade protects the inside layers from being damaged. In preferred embodiments, a jet of air or other gas may be used to ease the insertion of the flat blade, or a gripping device which pinches the surface of the roll between opposed friction pads creates an arch in the surface of the roll through which the blade is inserted. The device is particularly suitable for use in cigarette making machines which require undamaged paper feeds.

Description:
CLAIM FOR PRIORITY 
     Applicants claim priority, under 35 USC § 119, to European Patent Application 94810716.4, filed Dec. 12, 1994. 
     1. Field of Invention 
     The present invention pertains to a method and device for opening wound rolls of a supple material, such as paper or fabric. Such rolls are formed by spirally winding the material in superimposed layers, often on a separate support shaft. The roll has a top layer which can serve as a protection layer, the free or “loose” end of which may be attached to the layer directly beneath it, frequently by means of glue. 
     The roll has two parallel sides formed by the edges of the wound material. The method and the device according to the invention are particularly useful for relatively narrow rolls, namely, those delivering a strip having a maximum width of the order of several centimeters. 
     2. Description of the Prior Art 
     Various disclosures, in particular U.S. Pat. Nos. 5,018,535, 4,995,406 and 5,169,082, describe different methods and devices which open a roll of paper or other material to be fed into a manufacturing machine and those disclosures are incorporated herein by reference. 
     These publications generally provide for a cutting blade that is perpendicular to the unwinding direction of the strip and is applied to the top layer of the roll in order to cut it. Since the cutting blade is pressed onto the top layer with a certain force and/or is inserted a certain distance into the roll, several layers of the roll generally are cut simultaneously, with no way of verifying how many layers have been cut. 
     With these systems, it often happens that the next layer directly below the last cut layer is damaged by the blade, thus making a weak point that could cause the strip to break at that location at some future time. A break of this type requires a shutdown of the machine which uses the roll of wound material, resulting in a loss of productivity. 
     In certain cases, the top layer of the roll is covered with a protection band made of a material that can be different from that of the roll. In the following description, the “top layer” of the roll refers to any of: this protection band (if present), the first layer or layers of the roll, or to the protective band and the first layer or layers of the roll. 
     Application DE 3,215,355 describes a device with a support bar on which are mounted a cutting blade and a layer separating blade. The separating and cutting actions are controlled simultaneously by the movement of the support bar. This device unfortunately makes it impossible to adjust the distance between the support bar and the separating blade, and it is fairly difficult to minimize the height travel setting for the separating blade. As a result of this difficulty, an excessive number of layers must be cut leading to waste. 
     Furthermore, if the force of the separating blade spring decreases after long use, there can be insufficient compressive force between the support bar and the separating blade, and thus it is possible that one or several layers between the support bar and the separating blade might not be severed properly. 
     Regarding the paper on the roll itself, since the support bar rests directly on the top layers, the latter is compressed, making it more difficult to insert the separating blade. Also, because the advancing movements of the support bar against the upper layer and those of the separating blade are simultaneous with the cutting movement, the layers to be cut are shifted, causing damage to the layer directly beneath the separating blade and preventing a clean cut of the layers. 
     Moreover, this device is not capable of making multiple cutting passes, and the fact that the cutting blade is attached to the support bar makes it difficult to replace a worn blade. Furthermore, this device does not have any means of relaxing the tension of the top layers of the roll if said layers are tightly rolled, in which case it is impossible to use the device. 
     DE 3,918,552 and U.S. Pat. No. 4,821,971 describe devices for opening wide rolls. The problems encountered in this case are essentially different from those which the present invention solves. In particular, devices in these disclosures cannot insert the layer separating blade across the entire width of the roll. 
     SUMMARY OF THE INVENTION 
     The device according to the present invention provides a method for opening a roll without damaging the layers which underlie the outer layer of the roll. A flat blade is inserted between the outer layer to be cut and the center of the roll, and the cutting action stops at the flat blade. In one embodiment, the novel device contains a gripping mechanism which grips the top layer or layers of a roll and draws the surface together to form an arched space under that layer. A flat blade is provided for insertion into the roll, preferably at an arched space as described above, and a cutting blade is provided which cuts the top layer, and at the end of its cut is stopped by the flat blade. The layers may also be separated by a jet of air or other gas to ease the insertion of the blade, and the roll may optionally be turned. 
     One object of the invention is to provide a method compatible with conventional roll handling methods, but which does not have the disadvantages of the prior art and which ensures that the layer directly below the last cut layer is absolutely intact and damage-free, even if the top layer of the rolls are tightly wound. 
     Another object of the invention is to provide a device for opening a roll with a minimum of damage to the layers, which device can be adapted to a known device for roll opening and that preserves intact the layer directly below the last layer to be cut, even if the top layers of the roll are tightly wound. 
     An additional object is to provide a device and method for opening a sealed roll which is compatible with cigarette manufacturing machines. 
     These objects are achieved by the device and method of the present invention. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention is best described with reference to the following drawings, which are provided by way of illustration and not limitation. 
     FIG. 1 is a front view of an embodiment of a device according to the invention in the ready position; 
     FIG. 2 is a side view of the device illustrated in FIG. 1 in the same position; 
     FIG. 3 is a front view of the device of FIG. 1 in operation; 
     FIG. 4 is a side view of the device of FIG. 2 in operation; 
     FIG. 5 is a front view of a second embodiment of a device according to the invention in the ready position. 
     FIG. 6 is a side view of the device of FIG. 5; 
     FIG. 7 is a front view of the device of FIG. 5 in operation; 
     FIG. 8 is a side view of the device of FIG. 6 in operation. 
     FIG. 9 is a side view of the device of FIG. 6 after the cutting stroke. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1, an exemplary device according to the present invention  1  is shown mounted above a roll  2  that is attached to a support shaft (not shown) and has several layers  20 , in particular a top layer  21 , the end of which is glued on to the layer directly beneath it in order to seal the roll and prevent unwinding. The roll  2  has two lateral surfaces which comprise its two parallel sides  22 . 
     During the process, the roll  2  is generally stationary on its support shaft, although it is not necessary that it be tightly fit on said shaft. One embodiment of the device  1  comprises a first actuator  10 , which may be for example a hydraulic or pneumatic cylinder, the barrel of which is attached to a machine structure  3  by mounting arrangement  30  which may also be movable. 
     In some cases, the mounting arrangement  30  is movable and can permit the device  1  to be moved into position above the roll  2  for its operation to assist in opening of the roll and then retracted so that it does not interfere with the subsequent operations to be performed on the roll. It is assumed that, during the operation of the opening device  1 , the outer casing of the actuator  10  (in this case the cylinder barrel) is fixed and immobile with respect to the roll  2 . The actuator  10  comprises a movable rod  11  that can travel in either direction perpendicular to the roll support shaft and that points toward said support shaft. 
     The end of the movable rod  11  of the cylinder  10  is attached to a first support  12  that extends parallel to the roll support shaft, preferably behind the roll  2  as shown in FIG.  2 . Guide  12 A prevents the rotation of the support  12  in order to keep the support  12  aligned with the roll support shaft. At the back end of the support  12 , a column  12 B keeps a blade holder  13  at a certain fixed vertical distance from the support  12 . 
     A flat blade  13 A can slide into the blade holder  13  in a direction parallel to the support shaft of the roll  2 , and can move from the retracted position shown in FIG. 2 to a position extended toward the roll  2 , as shown in FIG.  4 . The extension and retraction movements of the flat blade  13 A are produced by a second hydraulic or pneumatic actuator  13 B built into the blade holder  13 . 
     A second support  14  generally oriented in a direction perpendicular to the support shaft of the roll  2  and also to the direction of motion of the movable rod  11  is attached to the underside of the support  12 . A double set of cross-linkages  15 , each consisting of a pair of bars  15 A and  15 B, is mounted on the two sides of the support  14  parallel to the sides of the roll  2  and below said support. 
     A first center pin  16  connects each of the cross-linkages  15 , said pin being preferably in the center of each of the bars  15 A and  15 B, permitting said bars to pivot about said first center pin. The upper end of each bar  15 A is fixed against the opposing surface of the support  14  by means of a second pin  16 A which extends through said support and allows said bars to pivot simultaneously about said second pin. The upper ends of the bars  15 B are similarly connected by a third pin  16 B, said pin being capable of sliding, in a direction perpendicular to the shaft of the roll  2  and also to the travel of the first movable rod  11 , in a slot  14 A that traverses the support  14  and extends in the direction of the second pin  16 A. 
     The distal end of the support  14  in relation to the end attached to the support  12  supports a third actuator  17 , which also can be a hydraulic or pneumatic cylinder and which has a second movable rod  17 A, the end of which is attached to the pin  16 B and is capable of moving said pin in a parallel manner in the slot  14 A and in the direction defined above. The lower ends of each of the bars  15 A and of each of the bars  15 B are connected by two fourth pins  16 C, said pins not pivoting with respect to the bars  15 A or the bars  15 B. 
     Each of the two pins  16 C supports a friction pad  18 , said pads being located beneath the lower ends and connecting together, respectively, the two opposing bars  15 A and the two opposing bars  15 B. The friction pads  18  thus are parallel to the support shaft of the roll  2  and each is covered on the surface facing the roll  2  with a coating having a high coefficient of friction with respect to the material comprising the layers  20  of the roll, for example, with rubber. Preferably, the contact surfaces of said coatings are rounded, and longitudinal grooves can be provided on said surfaces. Preferably, the spacing between the two opposing cross-linkages  15 , and thus the length of the respective friction pads  18 , is at least equal to the width of the material strip comprising the roll  2 . 
     In the position shown in FIG. 1, the movable rod  17 A of the actuator  17  is in the retracted position, and thus the pin  16 B is in the position farthest from the pin  16 A. By actuating the actuator  17  so that the pin  16 B approaches the pin  16 A, a scissors effect is obtained with the cross-linkages  15 , whereby the lower ends of the bars  15 A and  15 B of each cross-linkage converge, along with the two friction pads  18 . By means of the same scissors effect, the two friction pads  18  descend slightly toward the roll  2 . During the same movement, since each bar  15 A pivots about the pin  16 A, while each bar  15 B pivots in the opposite direction about the pin  16 B, the ends of the bars, and consequently the contact surfaces of the pads  18 , pivot slightly toward each other. 
     Also shown in FIG. 2 is a cutting device  4  which comprises particularly a cutting blade  40  and which is shown in the ready position. 
     Now the different steps of the method of opening the roll including the cutting of the top layer  21  of the roll  2  can be described. As mentioned above, the roll  2  is stationary on its support shaft. With reference to FIGS. 1 and 2, the mounting arrangement  30  for positioning the preparation device  1  are actuated so as to position said device close to the top layer  21 , the two friction pads  18  being slightly above the layer  21  and parallel to the roll shaft but not in contact with the layer  21 , while the blade  13 A is positioned several tenths of a mm below the upper surface of the top layer  21 . This distance at which the flat blade  13 A is positioned in relation to said upper surface depends essentially on the thickness of the strip of material comprising the top layer  21 . 
     In this position, the actuator  10  holds the movable rod  11  in the retracted position, while the actuator  13 B holds the flat blade  13 A in the retracted position and the actuator  17  holds the pin  16 B in the position farthest from the pin  16 A. This starting position of the device  1  in relation to the roll  2  can be set manually or automatically by a position detecting device (not shown, but which can be of the same type as that described below with regard to a second arrangement of the invention) connected to a control unit  9  capable of determining whether the device is correctly positioned above the layer  21  and whether the flat blade  13 A is correctly positioned relative to said layer. 
     After this starting position has been set, the actuator  17  is actuated, which moves the pin  16 B toward the pin  16 A, causing a downward movement where the contact surfaces of the friction pads  18  descend to contact and then press against the layer  21 , after which the two said pads converge with an accompanying pivoting movement. These movements of the two pads  18  suffice, after the latter are in contact with the top layer  21 , to slightly pinch the layer and then lift and form an arch  21 A between the two pads  18 , as shown in FIG.  3 . This arch  21 A in the layer  21  is thus caused by a combination of the above-described movements, first a strong contact between the pads  18  and the two distant surfaces of the layer  21  and then the convergence and pivoting of the two pads which, because of the high coefficient of friction of their coatings, do not slide over the layer  21 . 
     When the arch  21 A is created, the actuator  17  is stopped, and then the actuator  3 B is actuated in order to advance the flat blade  13 A so that the end of said blade passes through the space beneath the arch  21 A, that is, between the top layer  21  and the lower layers  20 . At this moment, the flat blade  13 A is maintained in this position and the cutting device  4 , along with the cutting blade  40 , is brought between the bars of the cross-linkage  15  directly above the arch  21 . 
     Thus the blade  40  can cut the arch  21 A, namely, the top layer  21 , while penetrating only as far as the flat blade  13 A, against which it finally comes to rest. Thus the flat blade  13 A has protected the first of the lower layers  20 , which thus cannot be damaged by the blade  40 . Preferably, the end of the flat blade  13 A inserted between the two layers of the roll  2  is rounded so as not to damage the layers. After this cutting operation has been performed, the cutting blade  40  is retracted, then the flat blade  13 A is retracted by the actuator  13 B, then the actuator  10  is again actuated in order to retract the pads  18  from the layer  21  and the movable mounting arrangement  30  moves the device  1  away from the roll  2 . 
     The top layer  21 , that which is cut by the blade, may comprise an outer protective layer, a single layer of wound material, or several layers of wound material. In a preferred embodiment, the arch  21 A consists of several top layers of the roll (and possibly a protection band as well) and thus several layers are cut. This is advantageous because if at least two layers are cut, then the place where the end of the top layer is glued to the layer directly below is sure not to be in the usable strip. 
     The various movements of the actuators are controlled by the control unit  9 . 
     Although the device for opening of a roll was described above by way of example in reference to a single preferred arrangement, other versions of this arrangement may be envisioned by one of skill in the art having regard for this disclosure. For example, it is not necessary that the device  1  be placed in a vertical position above the roll  2 , but in fact it could be oriented at any angle to the center of the roll, as long as the relative angles of the various movements described are maintained. 
     Similarly, the actuators described as being pneumatic or hydraulic cylinders could consist of any element capable of producing the movements described. Another arrangement could be proposed for the means of making the two pins  16 A and  16 B converge, for example, a rod having two sections threaded in opposite senses and being rotated by an actuator  17 , with one threaded section passing through a threaded hole in the pin  16 A and the other through a threaded hole in the pin  16 B. It is also possible that both pins could converge simultaneously, rather than only one pin moving. 
     Similarly, the center pin  16  was described as being in the center of each of the bars  15 A and  15 B, but in fact it could be shifted so that the movement of the pads  18  is multiplied or divided in relation to the converging movement of the two pins  16 A and  16 B. It is also possible that the support  14  for the cross-linkages  15  and the friction pads  18  can be independent of the support  12  for the blade  13 A, so that it can be moved away from the roll  2  after the blade  13 A has been inserted into the roll, so as to allow, if necessary, sufficient room for the cutting device  4 . 
     Another arrangement of a device for opening of a roll is shown in FIGS. 5 through 8. 
     As previously, a roll  2  comprising several layers  20  and in particular a top layer  21  is fit on a support shaft, which is not shown. This preparation device consists of a blade holder device  5 , a position detecting device  6 , and a control unit  9 , and also could be equipped with a blowing device  7 . These various elements are shown as separate from one another in order to make the figures clearer, but they are obviously part of the same group and are attached to a common plate equipped with displacement means capable of moving said elements into the operating position near the roll  2 . 
     The blade holder device  5  comprises a flat blade  50  which is exactly like the flat blade  13 A described above and which is capable of assuming a retracted position as shown in FIG. 5 or an extended position as shown in FIG. 8 by means of an actuator  51 . The blade holder  5  is mounted on another actuator  52  capable of positioning the flat blade  50  very precisely with respect to the top layer  21  of the roll  2 , as will be seen below. 
     Because not all rolls to be opened will have the same diameter, it is necessary to detect the position of the top layer  21 . For this purpose, a device  6  is provided to detect the position of said top layer by means of another actuator  60  equipped with a contact element  61 , preferably a roller, which at first is positioned well above the top layer  21 , as shown in FIG. 5, and then is lowered until the contact roller  61  touches the top layer  21 , as shown in FIG.  7 . 
     This positioning is controlled by the control unit  9 , which also can actuate the actuator  52  in order to place the flat blade  50  several tenths of a mm below the corresponding edge of the upper surface of the top layer  21 . The distance at which the flat blade  50  is placed relative to said upper surface depends on the thickness of the material strip comprising the roll  2 . 
     Assuming that the layers of the roll  2  are not too tight, the blade  50  is gently inserted beneath the top layer  21  and preferably, for the reason indicated previously with regard to the first arrangement, beneath at least the two top layers. This advancing movement of the flat blade  50  can be accomplished when the roll  2  is stationary or when the latter is rotating slowly in the direction from the roller  61  toward the flat blade  50 . 
     Preferably, the direction of this rotation is opposite to that of the normal unwinding of the roll, so that during this rotation the flat blade  50  tends to be pushed upward by the spiral winding of the roll layers. During this rotation, the roller  61  can continue to detect the position of the top layer  21  in order to correct the position of the flat blade  50  in case the roll  2  is not exactly circular. 
     When the flat blade  50  is completely inserted, the roll is stopped if it has been rotating and, as for the first arrangement described above, a cutting device  4  is brought in to cut the layers that are above the flat blade  50  and only those layers, the cutting movement being limited by the flat blade  50 . As shown in FIG. 6, the device can be augmented with a blowing device  7  consisting essentially of a blowing nozzle  70  which sprays a jet of pressurized air directly above the flat blade  50  toward the roll  2  in order to lift the top layers, thus facilitating the insertion of the flat blade  50 . A roller exerting force on the side of the roll may also be used. The detecting means  6  also can be designed so that there is no contact with the top layer  21 , for example, by employing an optical detection means. 
     The flat blade may optionally be formed with a groove along the width of the roll to guide the cutting blade and prevent damage to or dulling of the blade. 
     A device according to the arrangements or the variations described above makes it possible, when used in conjunction with a device for cutting and taking hold of the top layers of a roll, to obtain an intact strip of material for subsequent use, said strip not having been damaged by the cutting device.