Abstract:
The invention relates to a device for cutting off and conveying strips, for a machine. The device is used for producing a continuous web, especially of paper or card, for a threading strip, and has a knife. Finally the device is characterized in that it has it least one (preferably driven) guiding roll ( 27 ) which can be brought into engagement with the threading strip ( 27 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a device for cutting and transferring strips (streaks) which functions with a machine for producing a continuous material web, in particular a paper or cardboard web, and further relates to a method for cutting and transferring a threading strip inside a machine for producing a continuous material web, in particular a paper or cardboard web. 
     2. Description of Background and Relevant Information 
     Devices and methods of the type claimed here are known. They are used to introduce the web into the machine when starting the machine for producing, a continuous material web. Because the material web can be up to 8 to 10 meters wide, it is practically impossible to thread it simultaneously across its entire width. Therefore, a so-called insertion or threading strip, which is also called a belt, is cut from the material web. The threading strip is significantly narrower than the entire material web, for example, it is approximately 30 cm wide. This threading strip is threaded into the machine and, in the end, draws the entire width of the material web along with it. The threading process takes place, for example, when starting the paper machine or after a web tear. 
     At the beginning of a threading process, the threading strip, together with the rest of the material web, runs freely, i.e., it is conveyed away from the first drying cylinder. for example, of a drying section of the machine for producing a material web into the basement of the machine and is supplied to an additional treatment. In order to be able to guide the threading strip through the machine, it must first be severed, i.e., cut. At the beginning of the threading process, since the material web or its threading strip is traveling at the full machine running speed or at least is traveling at a speed that is only reduced by an insignificant amount, a back-up occurs during the cutting process due to which a further transfer of the threading strip is frequently problematic. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of the invention is to produce a device for cutting and transferring strips as well as a method for cutting and transferring a threading strip which do not have this disadvantage and assure an optimal cutting and transfer of the threading strip. 
     This object is attained with the aid of a device for cutting and transferring strips which has the features that will be herein described. The device is distinguished by means of at least one guide roll which is brought into engagement with the free-running threading strip and conveys it to the cutting point. It is therefore possible to prevent a paper backup when cutting the material web and to assure a trouble-free transfer of the threading strip. 
     A preferable exemplary embodiment of the strip cutting and transferring device is distinguished by the fact that the guide roll cooperates with a clamping device which preferably includes at least one clamping roll. This cooperation of the two rolls improves the guidance of the threading strip so that this makes a further contribution to the clean cutting and transfer of the threading strip. 
     Another preferable embodiment of the strip cutting and transferring device is distinguished by the fact that the rotation speed of the guide roll and/or of the clamping roll can be adjusted so that their circumferential speed is at least as high as the traveling speed of the threading strip. Since the two rolls engage each other, they basically rotate at the same speed. It is therefore sufficient to drive one of the two rolls and to choose to have the circumferential speed of one of the two rolls be adjustable. Because of the adjustable rotation speed, the tension of the threading strip can be adjusted to a desired value so that a definite cutting process and a clean transfer of the threading strip are assured. 
     A particularly preferable embodiment of the strip cutting and transferring device is distinguished by the fact that the knife used for the cutting process is moveable. It is therefore possible to select the knife movement so that it travels in the transfer direction of the threading strip. As a result, the flee front end of the threading strip produced by the cutting process is deflected into the direction in which the threading strip is to be transferred. 
     In order to attain the object, a method for cutting and transferring a threading strip inside a machine for producing a continuous material web is proposed, which has the features mentioned herein. It is distinguished by the fact that the threading strip is supplied to the cutting point before the cutting. As a result of the defined position of the threading strip during the cutting, a paper back-up as well as transfer problems can be prevented. 
     A preferable embodiment of the method is distinguished by the fact that the threading strip is subjected to a definite initial tension before the cutting. This leads to a further improvement of the behavior of the threading strip when cutting. A back-up can be reliably prevented so that problems in the transfer of the cut strip end are practically eliminated. 
     Finally, another preferable embodiment of the method is distinguished in that the threading strip is cut by a knife which, for the cutting, is moved in the same direction as the free end of the strip end being cut. The free end of the threading strip produced in the cutting process thus receives an impetus in the direction of the subsequent travel of the threading strip. The method is therefore distinguished by a very high degree of operational safety. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in detail below in conjunction with the drawings. 
     FIG. 1 shows a schematic representation of a strip cutting and transferring device in a first functional position; 
     FIG. 2 shows a schematic representation of the strip cutting and transferring device in FIG. 1, in a second functional position; and 
     FIG. 3 shows a top view of a part of the strip cutting and transferring device. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The strip cutting and transferring device and the method for cutting and transferring a threading strip that are described below can basically be used in connection with any machine for producing a continuous material web. For the sake of example, it is assumed below that this machine is a paper making machine. 
     FIG. 3 a  is an alternative embodiment of the arrangement depicted in FIG. 3; and 
     FIG. 4 illustrates a view facing the nozzle. 
     The strip cutting and transferring device and the method for cutting and transferring a threading strip that are described below can basically be used in connection with any machine for producing a continuous material web. For the sake of example, it is assumed below that this machine is a paper masking machine. 
     When starting the machine, for example, when commencing production or after a web tear, the continuous material web is first conveyed away in its full width into the so-called basement of the machine and is later supplied to an additional treatment apparatus. A relatively narrow strip is cut from the material web with the aid of a known cutting device. First, the remaining material web and the cut strip, which later constitutes the threading strip, are permitted to fall into the basement. The strip cutting and transferring device is disposed at the point where the material web and the threading strip exit fiord a cylinder of the paper making machine, for example, a drying cylinder. 
     Upon activation of the strip cutting and transferring device, the threading strip is cut and the free end of the threading strip thus produced is threaded into the subsequent parts of the paper making machine. If the strip travels reliably inside the machine, the cutting device is moved so that the width of the threading strip becomes continually greater and therefore draws an ever wider strip of the material web through the machine. Finally, the entire width of the material web is thus conveyed through the machine. 
     The schematic depiction according to FIG. 1 shows a strip cutting and transferring device that is referred to below as the device  1  for short, which is integrated into a machine  3  for producing a continuous material web  4  and/or paper web. In the funtional position of the device  1  that is shown in FIG. 1, the material web  4  runs freely downward from a drying cylinder  5  of the machine  3 , following gravity, anad travels into a basement  7 . From there, the material web is supplied to a further treatment apparatus. The nateruak web  4  is picked up from the surface of the drying cylinder  5  with the aid of a doctor  9 , which is basically known so that its function and design are not discussed in detail here. 
     The device  1  includes a base  11 , which can be moved in the manner indicated by a double arrow  15 . for example, on a foundation beam  13 . A carrying device  17  is attached to the base  11  and cooperates with a counter support  19  which is likewise attached to the base  11 . In the exemplary embodiment shown here, the counter support  19  is connected to the base  11  by way of a pipe  21 . The carrying device  17  is fastened in an articulating fashion to the counter support  19  by a pivot axle  23 . A pivoting motion of the carrying device  17  in relation to the counter support  19  is produced, for example, by a piston/cylinder unit  25 , also called a pivoting cylinder, whose operation and function are basically known. The piston/cylinder unit  25  is suitably fastened to the pipe  21  on one side and to the carrying device  17  on the other side. 
     The pipe  21  is embodied so that it can be rotated in relation to the base  11 . This means that the carrying device  17  and the counter support  19  of the device  1  are disposed so that they can be moved and rotated in relation to the foundation beam  13 . 
     A guide roll  27  and a knife  29  are fastened to the carrying device  17 . Finally, another guide device  31  is also provided here which, in this instance, includes at least one air nozzle  33 , if necessary a plurality of air nozzles  33  distributed across the width of the threading strip. 
     The knife  29  is supported so that it can move in relation to the carrying device  17 . It cooperates with a piston/cylinder device  35 , which is connected to the knife  29  on one side and is suitably connected to the carrying device  17  on the other side. 
     The counter support  19  is provided with a clamping device and a guide device  39 . The latter includes a guide plate  41  and at least one air nozzle  43 . In this exemplary embodiment, the clamping device is constituted by a clamping roll  37 . In another exemplary embodiment (not shown), the clamping device includes a number of clamping rolls. Alternatively, it is also possible that instead of at least one clamping roll, the clamping device includes a guide device, for example, with a contact surface for the threading strip that is curved if necessary. 
     Above the counter support  19 , a web guide roll  45  is disposed onto which the threading strip, which is cut from the material web  4 , is to be guide. 
     The counter support  19  has a side wall  47  which is connected to the pipe  21  and encloses the pivot axle  23  on its one end—on the left in FIG.  1 . The clamping roll  37  is disposed at a distance from the pivot axle  23  so that the threading strip, which has been cut from the material web  4 , can travel downward between the pivot axle  23  and the clamping roll  37 . The guide plate  41  and the air nozzle  43  are disposed on the side of the clamping roll  37  remote from the pivot axle  23  and are situated between this clamping roll and the web guide roll  45 . The air nozzle  43  is embodied so that it produces one or a number of air jets which extend essentially parallel to the guide plate  41  and are directed toward the web guide roll  45 . 
     The carrying device  17  includes a first carrying arm  49  which cooperates with the pivot axle  23  so that the carrying device  17  is pivotably connected to the counter support  19 . On the end of the carrying arm  49  opposite from the pivot axle  23  the guide roll  27  is rotatably supported on the carrying aria  49 . 
     In the exemplary embodiment of the device  1  shown here, the counter support  19  is firmly connected to the pipe  21  in a stationary fashion while the carrying device  17  can be pivoted in relation to the counter support  19  and therefore in relation to the pipe  21 . In the functional position shown in FIG. 1, the carrying device  17  is pivoted upward counter-clockwise so that the guide roll  27  and the clamping roll  37  are disposed at such a distance that the threading strip cut from the material web  4  can travel between the two rolls into the basement  7 . 
     FIG. 2 shows the device  1  in its second functional position: through activation of the piston/cylinder unit  25 , the carrying device  17  is pivoted clockwise in relation to the stationary counter support  19  so that the guide roll  27  moves into the movement path of the threading strip of the material web  4  running freely from the doctor  9  into the basement  7 , The threading strip is therefore deflected toward the right by the guide roll  27 . 
     If the guide roll  27  is embodied as being driven, then it can guide the threading strip of the material web  4  so that the threading strip is stabilized. With another pivoting movement of the carrying device  17 , the guide roll  27  finally comes into contact with the clamping roll  37 . As a result, the threading strip of the material web is clamped between the guide roll  27  and the clamping roll  37  and reliably guided by them. 
     The guide roll  27  is driven with such a rotation speed that the circumference speed of the guide roll  27  at least corresponds to the traveling speed of the threading strip. Preferably, the rotation speed is selected so that the circumference surface of the guide roll  27  leads the threading strip to a certain extent and acts on it with an initial tension. A definite initial tension of the threading strip can be achieved, particularly when the threading strip is clamped between the guide roll  27  and the clamping roll  37 . 
     The knife  29  is fastened to the carrying device  17  so that it can be brought into engagement with the threading strip of the material web  4  and cuts this threading strip. The guide device  31  is embodied so that its at least one air nozzle  33  acts on the threading strip of the material web  4  with an air current which acts on the left side of the threading strip—in FIG.  2 —and exerts a force on it which acts in the direction of the web guide roll  45 . 
     FIG. 3 is a top view of a part of the device  1 , in the first functional position shown in FIG.  1 . The side wall  47  of the counter support  19  is visible, on the right end of which the clamping roll  37  is supported in a cantilevered fashion. The carrying, arm  49  of the carrying device  17  is also visible. The top view also shows that another carrying arm  51  is associated with the carrying arm  49  and is disposed on the opposite side. The guide roll  27  is rotatably supported between the carrying arms  49  and  51 . The depiction of the drive mechanism for the guide roll  27  has been omitted here. The knife  29  is supported so that it can be moved in relation to the carrying arms  49  and  51 . The movement of the knife  29  is produced by the piston/cylinder unit  35  which in this instance includes two individual elements which each have a piston and a cylinder and arc coupled to the knife  29 . 
     FIG. 3 shows the lateral edge region of the material web  4  from which the threading strip  53  is cut by a cutting device that is not shown here. In order to assure a reliable function of the device  1 . a separating device is provided here on the carrying arm  51  and has a projection  55  which assures that the threading strip  53  is guided between the projection  55  and side wall  47  while the remaining part of the material web travels outside the device  1 . Therefore. a distance is provided between the threading strip  53  and the rest of the material web  4 . 
     FIG. 3 is greatly simplified insofar as the depiction of a possible drive mechanism for the clamping roll  37  and the depiction of the guide device  39  have been omitted. Finally, the guide device  31  has also not been depicted here in order to permit a clear view of the knife  29 . 
     The function of the device  1  shown in FIGS. 1 to  3  and the method for cutting and transferring a threading strip will be discussed in detail below: 
     First, as indicated above, the material web  4  is conveyed in its full width away from the drying cylinder  5 , for example, into the basement  7  of the machine  3 . In this operational phase, the device  1  is disposed in its first functional position which is shown in FIG.  1 . This means that the guide roll  27  and the clamping roll  37  are disposed at such a distance from each other that the threading, strip  53  can travel unhindered away from the doctor  9  into the basement  7 . In this phase, the threading strip  53  does not touch either the guide roll  27  or the clamping roll  37 . 
     The carrying device  17  is now pivoted clockwise with the aid of the piston/cylinder unit  25 . As a result, the projection  55  engages with the material web  4  so that the threading strip  53  is assured of traveling at a distance from the rest of material web  4 . With another pivoting motion, the guide roll  27  comes into contact with the traveling threading strip. The guide roll  27  is preferably driven and rotates with a speed that corresponds to, and is preferably greater than, the traveling speed of the threading strip  53 . This produces a guidance of the threading strip  53 . 
     With another pivoting motion of the carrying device  17 , the threading strip  53  is finally deflected against the clamping roll  37  and is clamped between the guide roll  27  and the clamping roll  37 . These rolls rotate with such a speed that the threading strip  53  is reliably guided and is preferably acted on with an initial tension. 
     Due to the mobility of the base  11 , it is possible to assure that in the first functional position of the device  1 , which is shown in FIG. 1, the threading, strip  53  travels freely between the guide roll  27  and clamping roll  37 . 
     As soon as the treading, strip  53  is clamped securely between the guide roll  27  and the clamping roll  37  and has been supplied with an initial tension, the knife  29  can be activated by the piston/cylinder unit  35  and moved toward the right—according to the view in FIG.  3 . As a result, the knife  29 , which is embodied here as serrated, cuts the threading strip without creating a back-up. The cutting motion of the knife  29  occurs from left to right so that the threading strip  53  is acted on with an impetus directed toward the right. Through activation of the guide device  31 , which has at least one air nozzle  33 , an additional force directed toward the right is exerted on the free end of the threading strip  53  produced by the cutting process so that the free end travels to the guide device  39 . The free end of the threading strip  53  is guided on the guide plate  41  there to the web guide roll  45  and is additionally acted on with a guidance force which is produced by the air nozzle(s)  43 . 
     A reliable transfer of the free end of the threading strip  53  produced in the cutting is assured because of the fact that the guide roll  27  supplies the threading strip  53  to the cutting. A back-up before the knife  29  can be avoided even at the top machine speed particularly by virtue of the fact that the threading strip  53  is acted on with an initial tension before the cutting so that the free end produced is acted on with an impetus directed in the transfer direction right during the cutting process and is reliably conveyed onward by guide devices. 
     The device  1  and the method described here are distinguished not only by a high degree of functional reliability but also by a high degree of operational safety. This is also assured by the fact that the knife  29  is disposed protected between the carrying arms  49  and  51  and that the knife can be moved and brought into a retracted position as soon as a cutting process is finished. The danger of injury is thus reduced to a minimum. 
     The device  1  is also simply designed and can be brought into an optimal operating position because of the mobile base  11  and because of the ability to rotate the pipe  21 . It is therefore possible, for example, to rotate the device  1  slightly, i.e., to align it not exactly parallel to the travel direction of the material web  4 . Therefore, the threading strip  53  produced can be supplied to cable tongs, not shown here, which are provided immediately adjacent to the material web  4 . These cable tongs are basically known and are used to draw the threading strip  53  through the machine for producing the material web. Naturally, the device  1  can also be used in a machine for producing a material web in which a cable-free system is used in order to guide or draw the threading strip through the machine, for example, an air threading system. This system is known per se and therefore a detailed description has been omitted. 
     The clockwise pivoting movement of the device  1 , which is used to introduce the threading strip  53  into cable tongs in this exemplary embodiment shown in FIGS. 1 to  3 , is indicated by an arrow  57  in FIG.  3 . 
     Due to the mobility of the device  1 , after the threading strip  53  is threaded, it is possible to move the device  1  so that, in the event of a web tear, it does not hinder the material web  4  from coming, off of the drying cylinder  5 . 
     In the end, it is clear that the device  1  can also be modified insofar as the carrying device  17  can be embodied as stationary and the counter support  19  can be embodied so that it can pivot. The essential element is that in a first functional position, the threading, strip can travel freely between a guide roll and a clamping roll and, in a second functional position, this threading strip can be reliably guided and acted on with an initial tension. It is also immaterial in this connection whether the guide roll or the clamping roll is driven in order to produce the initial tension.