Abstract:
A mandrel is utilized to support a roll of material. The mandrel includes a retaining element, which can be placed on an inner circumference of a roll of material, and at least one carrier element which transmits a torque between the mandrel and the material roll. The carrier element can be engaged with the roll of material in a non-positive manner.

Description:
[0001]     CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0002]     This patent application is the U.S. national phase, under 35 USC 371, of PCT/DE03/01694, filed May 26, 2003; published as WO 03/104118 A2 and A3 on Dec. 18, 2003, and claiming priority to DE 102 24 839.7 filed Jun. 5, 2002, the disclosures of which are expressly incorporated herein by reference.  
       FIELD OF THE INVENTION  
       [0003]     The present invention is directed to an engagement or carrier element, to a method for producing an engagement or carrier element, as well as to a mandrel. The engagement or carrier element is used to transmit torque and has a cutting edge with cutting faces.  
       BACKGROUND OF THE INVENTION  
       [0004]     Mandrels for use in seating rolls of material, in particular for seating paper rolls, are generally known in the paper and printing industry. Such mandrels are employed at the roll changers of web-fed rotary printing presses to rotatably seat or support the rolls of material, from which the paper to be imprinted is drawn off, during operation of the web-fed rotary printing press. A so-called flying roll change is often performed at such roll changers. In this connection, a flying roll change means that gluing of a leading end of a fresh roll, to a tensioned web of an exhausting paper web, can be performed while the tensioned, exhausting paper web continues its running off. Only fractions of seconds are available for performing such a flying roll change, during which time the tension, tensile stress and shearing strain must be exactly maintained.  
         [0005]     To be able to perform a flying roll change, the fresh paper web roll must be accelerated in such a way that its circumferential speed corresponds exactly to the linear speed of the paper web which is running off. The torque required for accelerating the fresh roll of the web of material is transmitted to that roll by appropriately suitable drive systems. In this connection, so-called belt-drive systems are known, for example, wherein drive belts are brought into contact with the circumference of the fresh roll. These belt-drive systems accelerate the fresh roll by the use of an appropriate frictional connection between the belts and the roll outer surface. Moreover, so-called cardan drives are known, wherein the required drive torque is transmitted to receiver elements, which receiver elements come into contact with the roll of material on both of its sides.  
         [0006]     A mandrel is known, for example, from EP 0 453 800 B1. With this mandrel, radially drivable, spreading cheeks are provided at the receiver element which cheeks, after the receiver element has been arranged in a core of the roll of material, can be moved apart to make a frictional connection between the roll of material and the mandrel. It is not inconceivable, in connection with such mandrels with radially spreading cheeks that, because of the high inherent weight of the roll and thus because of the resultant high moments of acceleration, the roll of material will slide over, or with respect to the clamping cheeks during roll acceleration or braking. This undesirable slippage can cause irregularities in the movement progress of the roll. Furthermore, the interior surface of the core of the roll of material can be damaged by such a sliding of the spreading cheeks with respect to the core, so that a secure fastening of the roll of material on the mandrel is no longer provided.  
         [0007]     DD 82615 describes a clamping device for winding tubes. Several clamping pins, with knife-like cutting edges, are pressed into the winding tube.  
         [0008]     DE 28 32 361 A1, DE 21 00 746 A, DE-PS 972 578, GB 2 293 225 A and DE 73 17 470 U all disclose mandrels with engagement elements which engage the web of material by positive contact.  
       SUMMARY OF THE INVENTION  
       [0009]     The object of the present invention is directed to providing an engagement element, to a method for producing such an engagement element, as well as to a mandrel including such an engagement or carrier element.  
         [0010]     In accordance with the present invention, these objects are attained by the provision of an engagement element for use in transmitting torque and which engagement element has a cutting edge with cutting faces that cross each other and that form a wedge angle. The engagement element penetrates into the object to be driven. The cutting faces may each have a convex shape. The engagement element can be fabricated by forming a first one of the cutting faces into an end of a profiled rod, by then rotating the rod by 180° about its center axis and by then forming the second one of the cutting faces. A mandrel for supporting a roll of material can include the engagement element. The mandrel can include a roll core stripping switching arrangement.  
         [0011]     The advantages to be realized by the present invention consist, in particular, that by the arrangement of appropriately suitable engagement elements, it is possible to make a positive connection between the roll of material and the mandrel. Based on this positive connection, a considerably more dependable transmission of a driving torque from the mandrel to the roll of material is assured. Furthermore, in embodiments wherein non-positively or frictionally connected engagement elements are not provided in addition to the positively connected engagement elements, it is possible, in such embodiments, to omit the mechanically elaborate drive mechanisms that are typically provided for adjusting such non-positively or frictionally connected engagement elements. In this connection, it is, of course, also possible to combine the engagement elements acting in a positively connected manner with generally known, non-positively or frictionally connected acting engagement elements, such as, for example, spreading cheeks.  
         [0012]     In accordance with preferred embodiments of the present invention, the engagement elements are arranged on the mandrel in such a way that they can be brought into engagement with an end or front face of a roll of material and will extend substantially parallel to the longitudinal axis of the roll of material. By the use of this configuration, it is possible to achieve that, by the displacement movement of the mandrel, in the course of putting the roll of material on the shaft, and during which movement the receiver element is axially introduced into the core of the roll of material, the engagement elements are pressed, in a positively connected manner, into the front or end face of the roll of material without the need for, or use of an additional displacement drive mechanism. A separate displacement drive for adjusting the engagement elements, which act in a positively connected manner, can then be omitted.  
         [0013]     A particularly uniform force introduction from the mandrel into the roll of material is assured if at least three engagement elements are provided, which three engagement elements are arranged, in a circular shape, around the center of the receiver element. The number of engagement elements can be increased to correspond to the level of the forces to be transmitted.  
         [0014]     To provide a positive connection between the engagement element and the roll of material, appropriately suitable receivers can be provided on the roll of material. The engagement elements of the mandrel can be brought into engagement with these receivers when the roll of material is put on the shaft. However, the provision of such receivers on the roll of material requires an additional production outlay. This additional production outlay can be avoided if a cutting edge is provided on the engagement element. By the provision and use of this cutting edge, the engagement element can penetrate the material of the roll of material, which may be, for example, the wall of a cardboard tube, with a relatively low pressing force. At the same time, tearing or ripping of the material of the roll of material is prevented because of the provision of the cutting edge. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     A preferred embodiment of the invention in accordance with the present invention is represented in the drawings and will be described in greater detail in what follows.  
         [0016]     Shown are in:  
         [0017]      FIG. 1 , a cross-sectional view of a mandrel in accordance with the present invention, in  
         [0018]      FIG. 2 , an enlarged view of a portion of the mandrel which is depicted in  FIG. 1 , in  
         [0019]      FIG. 3 , an enlarged view, partly in cross-section of a portion of the mandrel in accordance with  FIG. 2 , in  
         [0020]      FIG. 4 , a first side elevation view of an engagement element for use with a mandrel in accordance with  FIG. 1 , in  
         [0021]      FIG. 5 , cross-sectional views of a cutting edge of the engagement element in accordance with  FIG. 4  and taken along the section lines B-B and C-C, respectively of  FIG. 4 , in  
         [0022]      FIG. 6 , a second side elevation view of the engagement element in accordance with  FIG. 4 , in  
         [0023]      FIG. 7 , a partial cross-sectional view of a cutting edge of the engagement element in accordance with  FIG. 6  and taken along the section line A-A of  FIG. 6 , in  
         [0024]      FIG. 8 , a schematic presentation of a device for producing the engagement element in accordance with  FIG. 3  in a side elevation view, and in  
         [0025]      FIG. 9 , a front plan view of the device in accordance with  FIG. 8 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]     A mandrel, generally at  01  and represented in  FIG. 1 , is fastened to a frame of a roll changer  02  in a web-fed rotary printing press. A rotationally symmetrical receiver element  03  is provided on the mandrel  01 , which receiver element  03  can come into contact with an interior circumference of a roll  04  of material. In particular, the receiver element  03  can come into contact with the interior circumference of a cardboard tube or roll  04  on which a web of material, and in particular, on which tube or roll  04  a paper web has been wound. The receiver element  03  is rotatorily seated in rolling bearings and can be rotatorily driven by the use of an electrical drive mechanism. When placing the roll  04 , used for the support of a web of material, on the shaft, two generally identical, opposing mandrels  01  of the roll changer  02 , only one of which mandrels  01  is represented in  FIG. 1 , are moved toward each other in the axial direction. The receiver elements  03  are thus introduced into the hollow core from the direction of the front or end face of the roll of material or the tube  04  that is used for support of material such as a paper web.  
         [0027]     In  FIG. 2  there is depicted an enlarged view of the mandrel  01  following the placement of the roll  04  of material on the receiving element  03 . Several engagement elements  06  are arranged, distributed in a circle concentrically around the center of the receiver element  03 , on the mandrel  01 . Only one of these plural engagement elements  06  is represented in  FIG. 2 . An end of each engagement element  06 , pointing toward an end face of the roll or tube  04  used to support the web of material, has a cutting edge  07  which cutting edge  7 , in the course of the two opposing mandrels  01  moving together, enters into the end face of the roll of material  04  or into the tube  04  that supports a web of material and in this way makes a positive connection between the roll  04  of material or the tube and the mandrel  01 .  
         [0028]     The structure of a representative one of the engagement elements  06  is represented, by way of example, in FIGS.  4  to  7 . A cutting edge  07  of the engagement element  06  is defined by two cutting faces  08  and  09  which intersect each other, and which enclose a wedge angle α of 25° to 45°, and in particular of approximately 34°. Both of the two cutting faces  08  and  09  each have a convex shape, since they are being constituted by sections of generated cylinder surfaces which cross each other. The convex curvature of one of the cutting faces  08  and  09  can be seen, in particular, in the cross section taken along the section lines A-A of  FIG. 6  and represented in  FIG. 7 . By the use of this type of configuration of the engagement elements  06 , it is achieved that, in the course of a torque transmission, the tip of the engagement element  06  is stressed by a bending stress which is substantially constant over the cross section. This stress distribution is something which permits an optimal utilization of the material.  
         [0029]     The wedge or cutting angle α 1  which is an acute angle α 1  during the initial penetration of the cutting edge  07  into the roll  04  of material, makes a transition, in the course of increasing penetration depth, into an obtuse angle α 2  as far as the round cross section of engagement element  06 . The wedge angle α becomes continuously larger along the cutting edge  07 . This favors the displacement of the material, in the course of an increasing engagement element cross section.  
         [0030]     The core material, at the penetration point of the engagement element  06 , is initially cut effectively and without damaging further cardboard layers because of the initial small width of the tip of the cutting end of the engagement element  06 . In this context see the section lines B-B of  FIG. 5 . With increasing penetration depth of the cutting edge  07 , the core material is appropriately displaced. In this regard see section line C-C shown in  FIG. 5 .  
         [0031]     The angle α 1  continuously increases to the angle α 2 . Because of this, the penetration depth of the cutting edge  07  of the engagement element  06  into the roll  04  of material is minimized.  
         [0032]     The several engagement elements  06 , only one of which is depicted in  FIG. 2 , are fastened on the mandrel  01  by the provision of a clamping ring  11 , as is also seen in  FIG. 2 . A circular flange  12  has been formed on, or attached to an end of the engagement element  06  that is located opposite the cutting edge  07 . Flange  12  secures the engagement element  06  against slipping out of the clamping ring  11 . Furthermore, two tool engagement faces  13  or  14  have been formed on a shank of the engagement element  06  intermediate cutting edge  07  and flange  12 , and against which faces an assembly tool can be brought to act.  
         [0033]     As shown in  FIG. 2 , and in the enlarged view in  FIG. 3 , the engagement elements  06  pass through a switching arrangement  16  which is embodied in the manner of a lift-switching ring  16 , which can be brought into flat contact with the front or end face of roll  04  of material or tube  04 . In each of  FIGS. 2 and 3 , the switching arrangement  16  is represented in a clamping position which it assumes following the placement of the tube or the roll  04  of material on the shaft of the mandrel  01 . The switching arrangement  16  is seated in an axially displaceable manner and is supported on the clamping ring  11  by several springs  17 , for example by several helical springs  17 . In the course of placing the tube or the roll  04  of material on the shaft, its end face is pressed against the switching arrangement  16  and is clamped by the helical springs  17 . The spring constant of the helical springs  17  has been selected to be large enough so that the spring force is sufficient to strip the tube or the roll  04  of material off the engagement elements  06  when the mandrels  01  are moved apart. This means that by displacing the switching arrangement  16  out of the clamping position represented in  FIGS. 2 and 3 , and into an advanced or extended ejection position, the roll  04  of material is taken out of positive engagement with the engagement elements  06  and can therefore be easily removed from the mandrel  01 .  
         [0034]     A contactless, operating sensor  18  is provided on the mandrel  01 , by the use of which sensor  18  the position of the switching arrangement  16  can be detected. In other words, by evaluating the output signal from the sensor  18  it is possible to determine, in a control device of the installation, whether the switching arrangement  16  is in its clamping position or in its ejection position. In other words, it is possible to detect, by this signal evaluation, whether or not a roll  04  of material has been placed on the shaft of the mandrel  01 .  
         [0035]     A device for producing an engagement element  06 , in accordance with the present invention, is schematically represented in  FIG. 8 . In a first process step, a first concave cutting face  08  of the engagement element  06  is cut into an end of a profiled rod by the use of a form-grinding wheel  19 . In the course of this process, the end of the profiled rod is placed into engagement with the form-grinding wheel  19  at an acute angle α/2, which corresponds to half the wedge angle α. As soon as the first cutting face  08  has been formed on the end of the engagement element  06 , the profiled rod is rotated by 180° and processing is analogously repeated on the opposite side of the end of the engagement element  06 , so that the second cutting face  09  and the cutting edge  07  are formed into the engagement element  06 .  
         [0036]     The concave circular profile  21  of the form-grinding wheel  19  can be seen most clearly in  FIG. 9 . Because of this profile, the production of cutting faces  08  and  09 , which cutting faces  08  and  09  have the shape of a section of a generated cylinder surface, is possible through the use of the form grinding wheel  14 .  
         [0037]     While preferred embodiments of a carrier or engagement element, a method for making an engagement element, and a mandrel including such an engagement element have been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that various changes in, for example, the size of the mandrel, the number of engagement elements positioned about the mandrel, and the like could be made without departing from the true spirit and scope of the present invention which is accordingly to be limited only by the appended claims.