Abstract:
A material roll is transported to a roll changer by being arranged on a transport carriage. The material roll and transport carriage are placed on a transfer table which is moved into position between journal bearings of the roll changer. The transfer table is adapted to move the material roll transversely and along a longitudinal axis of the material roll and can pivot in a horizontal plane. An inclined position of the material roll, arranged on the transfer table, is determined by sensors. In this determined, axially aligned position, the material roll is axially aligned on the bearing journals. The roll size of the material is determined. An axially aligned position for roller support arms of a roll carrier of the roll changer is determined as a function of the determined roll size. An axially aligned position of the transfer table is determined as a function of the determined roll size and the determined inclined position of the material roll. The position of both ends of the sleeve of the material roll, upon insertion of the transfer table into the roll changer, is detected. The material roll is then inclined by a rotary drive which is arranged on the transfer table.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is the U.S. national phase, under 35 USC 371, of PCT/EP2006/062363, filed May 17, 2006; published as WO 2007/006600 A1 on Jan. 18, 2007 and claiming priority to DE 10 2005 032 600.5, filed Jul. 13, 2005, the disclosures of which are expressly incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention is directed to methods and to a device for orienting a material roll to be transported to a roll changer. The material roll, that is positioned on a roll transport structure or roll carriage, is oriented on a transport carriage both of which form a transfer table which can be moved into position between bearing journals of the roll changer. The transport carriage is arranged as part of the transfer table, which transfer table is capable of moving the material roll transversely and along a longitudinal axis of the material roll, and of pivoting within a horizontal plane. 
     BACKGROUND OF THE INVENTION 
     A station for loading a roll changer is known from EP 0 227 887 A2, in which a material roll is moved on a transport structure into position between roll support arms having clamping jaws, where it is raised by the transport structure. Various sensors are used for transverse centering and to detect the alignment of the roll axis and the center axis of the clamping jaws, and to register and to control the advancement of the transport structure in a horizontal direction. 
     EP 03 91 061 A1 describes a system for loading a roll changer. A material roll is first placed in a rough adjustment position, and then is placed in a fine adjustment position, separately from the roll changer. The fine adjustment position corresponds to the position of the loading cones in the roll changer. In this fine adjustment position, the material roll is held in place on a transport structure, and is then moved into the roll changer in a horizontal direction, by use of the transport structure. 
     DE 37 31 488 A1 relates to a device for clamping a replacement web of material. Various sensors ensure a precise positioning of the rolls below the clamping point. Sensors also determine the diameter of the replacement roll, from which diameter determination the sensors then determine the necessary clamping height. If necessary, the roll of material is raised to the necessary height by the use of a lifting device. The roll core is detected by a photoelectric sensor, and additional sensors detect the position of the roll when it reaches the roll changer. 
     DE 38 22 572 C2 describes a roll unwinding device for wound rolls of web-type material. The device enables the utilization of an automatic process for orienting the wound roll, taking into account the actual position of the core ends, without requiring the provision of a separate measuring station. 
     In U.S. Pat. No. 4,131,206 A, an automatic device for supplying a roll of material in a rotary printing press is described. Through the use of a dual-truck mechanism, a new roll of material is transported to the printing press, where it is clamped in the roll support via automatic positioning, and the empty core is removed. Sensors determine the parameters and the position of the roll, and enable an automatic removal of the empty core from the axle. 
     WO 89/08598 A1 shows a device for orienting a material roll prior to loading the roll on the axle in a roll changer. A transfer table is arranged with a transport carriage that can be moved thereon. The table can be moved transversely to a longitudinal axis of the material roll, between two bearing journals of the roll changer. The transfer table is arranged so as to transport the material roll into position between two bearing journals of the roll changer. The transfer table enables a displacement of the material roll along its longitudinal axis and a pivoting of the material roll around its longitudinal axis. Elements for detecting the position of the material roll are provided. The position detection devices are arranged so as to detect an oblique position of the material roll arranged on the transfer table. 
     DE 43 34 582 A1 discloses a roll changer, whose bearing arms and transfer table are positioned based upon a determined roll size. 
     Problems arise when the position of the roll, that has been pre-adjusted in this manner, is altered by external forces with the transfer table as it is being moved into the roll changer, or when, as a result of winding errors on the core, the pre-positioning cannot be precisely guaranteed. Especially in the case of large roll widths, this roll position alteration frequently leads to problems in loading of the roll onto the axle of the roll changer. In addition, these wide rolls are subject to other dimensional tolerances, thus making a precise positioning of the roll, during loading of the roll onto the axle, even more important. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is therefore directed to the devising of methods, and to the provision of a device for orienting a roll of material to be transported to a roll changer. 
     The object is attained according to the present invention with the provision of the material roll being transported to the roll changer positioned on a transport carriage which is, in turn, part of a transfer table. The transfer table is moved into position between bearing journals of the roll changer. The transport carriage is arranged as part of the transfer table which is capable of moving the material roll transversely and along a longitudinal axis of the material roll, and of pivoting the material roll within a horizontal plane. Sensors are used to determine the size of the roll and its oblique positioning on the transfer table. The positions of the two roll core end surfaces are determined, as the transfer table is moved into the roll changer. The material roll is then loaded on the roll changer. 
     The benefits to be achieved in accordance with the present invention consist especially in that, without additional process steps, the material roll can be positioned correctly in the roll changer for automatic placement on the axle of the roll changer. 
     A roll of material is moved into the roll changer with the use of a transfer table. The roll of material can be pivoted on its longitudinal axis on the transfer table as it is being moved by the transfer table. 
     This movement of the roll of material can be accomplished, for example, by the use of a rotating mechanism, which is integrated on the transfer table and which pivots the material roll around a vertical axis. If necessary, an additional lifting device, which is also on the transfer table, can raise or lower the material roll at one end or at both ends. This corresponds to a pivoting of the material roll on a horizontal axis, transversely to the longitudinal axis of the roll. With the pivoting, the roll of material can be aligned precisely to the bearing journals of a roll changer, which bearing journals will engage in the core of the roll. 
     A variety of options for positioning the material roll using such a transfer table exist, and will be specified in the discussion which follows. 
     A first option is for the material roll to be first moved on a roll carriage, such as, for example, a roll carriage that is rail-mounted, in a transfer table track. The roll carriage, with the material roll, is first positioned centered in the longitudinal direction on the transfer table. To this end, the transfer table is moved transversely to the longitudinal axis of the roll, in the direction of the roll changer, up to a measuring position. One or more measuring devices are mounted on the roll changer. These measuring devices measure a distance from the end surface of a new material roll to a fixed point, which measured distance especially occurs in the outer area of the roll and in the vicinity of the core. To this end, distance sensors are preferably positioned on the roll support arms as a part of a measuring device. These distance sensors determine the position of the core and the outside edge of the material roll at both ends of the material roll. The material roll is then moved, with the transfer table, into a position for loading the material roll onto the axle of the roll changer, that position having been determined from the measured values provided by the sensors. This axle-loading position corresponds to a theoretically optimal position for the material roll, with a parallel axial orientation, between the longitudinal axis of the material roll and the rotational axis of the bearing journals. 
     In the next step, the longitudinal axis of the core of the material roll is oriented through the operation of the rotational device and, if necessary, the lifting device. During this step, corresponding sensors supply measured values to the corresponding control devices. Loading of the material onto the axle is then implemented, through an axial movement of the bearing journals of the roll changer toward the center of the material roll. The transfer table is then moved back to its starting position, if applicable, after the transfer table or the lifting device has been lowered or the material roll has been raised with the help of the roll support arms. 
     Another option for roll positioning includes first determining the diameter of the roll of material on the transfer table, and from this, determining values for the axle-loading position for both the roll support arm and the material roll. The roll support arm and the transfer table are then moved into this position. Sensors on the roll support arm determine the actual position of the core and, based upon the deviation of that actual position from the optimum axle-loading position, the rotational device and/or, if necessary, also the lifting device is actuated until the axle-loading position is actually reached. After the roll has been loaded onto the axle, the transfer table is returned to its starting position. 
     A simpler solution would involve the use of a transfer table without the inclusion of a lifting device. In this case, as in the aforementioned variation, the transfer table is first moved into the axle-loading position, and the rotary drive is switched to free-running operation. The material roll is then rotated, during the axle-loading process, by the freely movable rotating device, as the first bearing journal is being moved into position, in such a way that the axis of the core is aligned coaxially to the axis of the bearing journal, and the second bearing journal is now able to move into position in the core. This embodiment can also be configured as a manual embodiment, in which the track on the transfer table is secured against rotation, and can be released manually as needed. 
     In one preferred embodiment of the present invention, after the aligned loading of the material roll onto the axle of the roll changer, parts of the loading device are also used to align the edges of the expiring material web and of the new material web. In this embodiment operation, not only is the position of an edge of the new material web detected, but a distance between the end surface of the new material roll and a fixed point is also detected. The roll positioning sensor is preferably used for this. With this procedure, the independent displacement of a distance sensor can be dispensed with. 
     The measuring device in accordance with the present invention is preferably an optical position sensing system, which permits contactless measurement. With modified embodiments, however, other measurement systems, such as, for example, radar systems, acoustic sensors or interferometric sensors, can also be used. 
     The measuring device is preferably mounted on a roll support arm of a roll changer. The advantage of providing the measuring device on the roll support arm is that only short measuring distances are necessary, which short measuring distances can be maintained, even with variable roll widths. In these cases, the respective sensor is moved along with the roll support arm, so that it always maintains a small distance from the material roll. Alternatively, the measuring device can be provided rigidly situated at the side of the roll changer frame. This is particularly beneficial when movable sensors are to be dispensed with. 
     In one preferred embodiment, the distance is measured at the end surface of the roll near the uppermost layer of paper, as the roll is being moved into the roll changer. To accomplish this result, the measuring device can also be positioned so as to be displaceable perpendicular to the roll axis. A displacement of the measuring device, in a radial direction, could also be coupled with a sensor for use in detecting a diameter of the new material roll. The necessary radial position of the sensor can then be automatically determined and adjusted. 
     As a desired value, a distance from an end surface of the roll to a relative fixed point in the roll changer, such as, for example, the roll support arm, which distance is desired under normal conditions, is determined. The desired value and the actual value must both relate to the same relative fixed point. 
     If the actual, measured value is the same as the desired value, the roll support arms of the expiring material roll and the new material roll are aligned with one another, at least in the case in which the width of the new material web is the same as that of the expiring material web. If the actual value differs from the desired value, the clamped new material roll is displaced in an axial direction by the amount of that deviation, by the use of a positioning drive. In any case, the positioning drive is provided on each roll support for lateral edge control during operation, so that no additional drive elements are necessary. With this, in the case of winding errors, and although, at the time the roll is changed, the two roll supports are no longer precisely aligned with one another, an edge offset between the material webs during gluing is prevented or at least is minimized. 
     Another option for orienting the material roll coaxially consists in also using distance sensors to measure the distance of a pivoting axis, from the outside of the roll, to both ends of the material roll. In this variation, variant, the material roll can be moved into the roll changer. If the distance measurement of the two end points of the roll results in a difference, the material roll is not aligned in parallel, and the rotary drive must be actuated. The rotary drive is decelerated when two equal measured values are reached, as determined by the distance sensors. Based upon the known roll diameter, the material roll can then be displaced parallel with the transfer table, until the axle-loading position is reached. 
     One option that is inexpensive, because complicated sensors and control systems are dispensed with, involves the use of touch sensors or of spring-mounted stops to align the material roll. To this end, in one preferred embodiment touch sensors can be provided on the ends of the roll support arms. The roll support arms are first moved into a closely spaced position, so that the material roll will not fit between them. The transfer table is initially shifted slowly in the direction of the roll changer. If the material roll lies in an oblique position, the touch sensor is actuated on the leading side of the roll, which activation of the touch sensor engages the rotary drive. Once the material roll is oriented in parallel with the roll supports, the touch sensor on the second support arm is actuated, which switches off the rotary drive and the displacement of the transfer table. A brake is also engaged, as needed. With lighter-weight material rolls, the torsional drive can also remain switched off, in which case, when the first touch sensor is reached, the torsional drive is momentarily switched on and, when the second touch sensor is actuated, is stopped again. Following adjustment of the roll support arms, the oriented material roll can be moved into the axle-loading position and then loaded onto the axle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the present invention are represented in the set of drawings, and will be specified in greater detail in what follows. 
       The drawings show in: 
         FIG. 1   a ) a side elevation view of a transfer table; in 
         FIG. 1   b ) a top plan view of a transfer table; in 
         FIG. 2  a side elevation view of a roll changer with a transfer table and a first positioning device, in a first embodiment of the present invention; 
         FIG. 3  a top plan view of the roll changer according to  FIG. 2 ; in 
         FIG. 4  a top plan view of a second positioning device in a roll changer; in 
         FIG. 5  a top plan view of a third positioning device; in 
         FIG. 6  a top plan view of a modified embodiment of the roll changer in accordance with the present invention; in 
         FIG. 7  views of a further preferred embodiment of a device for positioning a material roll in accordance with the present invention; in 
         FIG. 8  a side elevation view of a further preferred embodiment of a roll changer in accordance with the present invention and with a positioning device; in 
         FIG. 9  a top plan view of the embodiment according to  FIG. 8 ; and in 
         FIG. 10  various views of a preferred embodiment of a centering tip in accordance with the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to  FIG. 1 , there is shown a transfer table  01 , which is configured to perform a process in accordance with the present invention.  FIG. 1   a ) shows a side view of the transfer table  01  and  FIG. 1   b ) shows a top plan view of the transfer table. The transfer table  01  is essentially divided into two parts, and consists of a transport carriage  02  and a roll transport structure  03  configured as a part of the transport carriage  02  of the transfer table  01 . The transport carriage  02  can preferably be moved on wheels  04  on tracks  06 , which are also shown, for example, in  FIG. 2 , transversely to a longitudinal axis  07  of a roll to be transported. Additionally, a lifting device  08  can be provided as part of the transport carriage  02 , with which the height of the transfer table  01  can be adjusted on one side or on both sides. The lifting device  08  can preferably be supported on the tracks  06 . The lifting device  08  can be, for example, a correcting element  08 , such as an actuator cylinder  08 , and especially can be configured as a hydraulic piston  08  or as a pneumatic piston  08 . 
     A bearing ring  09  is provided on the transport carriage  02 , and which accommodates a transport rail  11  for the roll transport structure  03  and for its drive  12 , rotatably mounted thereon. A rotary movement of the bearing ring  09  is achieved through the use of a preferably electromotive bearing ring rotary drive  13 , which is preferably equipped with a planetary gear system, and which has an angular sensor that is not specifically shown in  FIG. 1 . In addition, a return of the bearing ring  09  to its starting position can be implemented via springs and/or by use of the rotary drive  13 . The bearing ring  09  is configured in the form of a rolling-contact bearing. The bearing ring  09  preferably has a circular shape and thus is preferably configured as a 360° closed ring. The rotational movement of the bearing ring  09  amounts to at least +/−10°, preferably amounts to +/−15°, but can also amount to 360° or more. The margin or end face surfaces of the rail  11  on the bearing ring  09  is rounded at the end surfaces at the transfer points and adjacent the tracks  06 , which are embedded in concrete, so that the rail  11  will not collide with the concrete edges during rotation. 
     The roll transport structure  03  can be centered in the longitudinal direction of the transport rail  11  by the provision of an initiator  14 . The initiator  14  can be implemented, for example, as a photoelectric sensor, which stops the drive  12  for the roll transport structure when the center position is reached. A simple stop would also be an option in this case. 
     In a simpler embodiment of the transfer table of the present invention, the lifting device  08 , including the hydraulic pistons  08 , can also be dispensed with. 
       FIG. 2  shows a side view of a roll changer  15  with a transfer table  01  for implementing a process for orienting a roll of material in accordance with the present invention. On a first roll support, which is comprised of two axially spaced roll support arms  16  lying one in front of another, in the plane of  FIG. 2 , an expiring roll of material  17  is clamped between bearing journals. A new material roll  18  has been transported, in advance, to the roll changer  15  and is transferred to the roll changer  15  via the roll transport structure  03 . The new material roll  18  is in a stand-by position in front of the roll changer  15 , as is depicted in  FIG. 2 . In this standby position, it can be the situation that the longitudinal axis  19  of the new material roll  18  is not yet aligned parallel to the center axis  21  of the bearing journals of a second roll support, which second roll support is, in turn, comprised of two roll support arms  22  lying one in front of another in the plane of  FIG. 2 . The oblique position of the new material roll  18  is schematically indicated in  FIG. 2  by a slightly perspective representation. A new material roll  18 ′, and having a smaller diameter is indicated by dashed lines. Its respective longitudinal axis is labeled  19 ′. 
     In the stand-by position, which is depicted in  FIG. 2 , the new material roll  18  or  18 ′ is first pre-positioned, centered between the roll support arms  22 . 
     In the stand-by position which is shown in  FIG. 2 , the diameter of the new material roll  18  or  18 ′ is determined by a sensor  23 , such as, for example, a diameter sensor  23 , which is preferably positioned in the frame of the roll changer  15 , again as may be seen in  FIG. 2 . This diameter determination is accomplished by measuring a distance of the upper side of the roll  18  or  18 ′ from the diameter sensor  23 . If the overall height of the diameter sensor  23  is known, the roll diameter can be determined in this way. 
     However, the roll diameter can also be determined in a different manner, for example by scanning a barcode label on the new material roll  18  or  18 ′. From the diameter of the new material roll  18  or  18 ′, a measuring position is determined, into which measuring position the second roll support with the roll support arms  22  is pivoted. In the depiction of  FIG. 2 , the roll support arms  22  are already shown in the measuring position. The roll support arm  22 ′, which is pivoted into the measuring position for the material roll  18 ′, which has a smaller diameter, is also indicated, in  FIG. 2 , by dashed lines. 
     As has already been specified in connection with  FIG. 1 , the transfer table  01  can be moved, through the use of the wheels  04  on the transport carriage, on the tracks  06 , and transversely to the roll longitudinal axis  19 , in the direction of the motion arrow  24 , as seen in  FIG. 2 . The bearing ring  09  is rotatably mounted on the transfer table  01 , and can be actuated via a bearing ring rotary drive  13 , which is especially constituted as an electric motor  13 . The roll transport structure or roll carriage  03  is mounted on the rotatable bearing ring  09 , and can be moved back and forth in the image plane of  FIG. 2  on the transfer table  01  via the roll transport structure drive  12 . 
     Position detection elements  26 , such as, for example, first sensors  26 , are attached to the roll support arms  22 , preferably at their ends, which position detection sensors  26  are spaced at a defined distance “x” from the center axis  21  of the bearing journals of the roll support arms  22 , as seen in  FIGS. 2 and 3 . The first, position detection sensors  26  are preferably positioned on the roll support arm  22  such that in a measuring position, the center axis  21  of the bearing journals, the longitudinal axis  19  of the new material roll  18 , and the first sensor  26  lie within a single plane, as is shown in  FIG. 2 . This offers the advantage that the measuring position of the roll support arms  22  also corresponds to the loading position, and the roll support does not need to be readjusted following measurement. 
     In the measuring position for the material roll  18 ′, as is indicated by the dashed lines of  FIG. 2 , the longitudinal axis  19 ′ or the center axis  21 ′ and the position of the sensor  26 ′ do not lie within a single plane. Therefore, in this case, the roll support arm  22  does need to be pivoted again after measurement. If a lifting device  08  is provided in the transfer table  01 , the material roll  18  or  18 ′ could also be raised to achieve alignment, and a readjustment of the roll support can be dispensed with. 
     It is also conceivable for separate or existing sensors to be provided for the most frequently processed roll diameter, such as, for example, between 1,250 and 1,500 mm, which separate or existing sensors are attached to the roll support arm  22  in such a way that the measuring position always corresponds to the loading position, and the corresponding sensors are activated following measurement of the roll diameter. 
     In a preferred embodiment of the present, the further process sequence for loading a roll of material  18 ,  18 ′ onto the axle will be specified, as taken in the context of  FIG. 3 , which shows a top plan view of the roll changer  15  of  FIG. 2 . The expiring material roll  17  is clamped with its roll core supported in spaced bearing journals  27 , which are each respectively mounted on one of a pair of spaced roll support arms  16  of the first roll support. 
     The roll support arms  22  of the second roll support are in the axle-loading position, as depicted in  FIGS. 2 and 3 . In other words, they are spaced further from one another, in an axial direction, than they would be in the clamped position, so that the material roll  18  can be moved into position, on the transfer table  01 , between the bearing journals  28  of the second roll support, as shown in  FIG. 3 . This positional movement is accomplished by moving the transport carriage  02  on the tracks  06  in the direction of the roll changer  15 , and transversely to the longitudinal axis  19  of the material roll  18 . A leading longitudinal or peripheral edge  29  of the new material roll  18  first passes the first sensors  26 . In this passing, a respective distance Z 1  and Z 2  from each of the end surfaces  31  of the roll to the sensors  26  is measured. If Z 1 =Z 2 , in the most favorable case, the longitudinal axis  19  of the new material roll  18  is already aligned parallel with the center axis  21  of the bearing journals  28 . However, if there is a winding error in the material roll  18  or if there is a core offset in the material roll  18 , a further criterion must be used for the coaxial alignment of the material roll  18  with the center axis  21  of the bearing journals  28 . 
     In this instance, wherein Z 1  may not be equal to Z 2 , the material roll  18  is first displaced further toward the roll changer  15  at a constant speed. This is followed by a detection of the roll core, in which the sensor  26  records and stores the measuring points M 1  and M 2 , as the core passes through a laser beam. The points M 1  and M 2  are detected separately at the two ends of the core portion of the material roll  18 , and from these points, an axial offset “y” is determined, as depicted in  FIG. 3 . Naturally, other sensors that determine the core position, such as, for example, by evaluating a change in a magnetic field, as the core passes through, can also be used for this measurement. 
     The axial offset “y” could also be determined simply from the difference in distance between the measuring points M 1  on both sides of the roll changer  15 . 
     When an axial offset, “y”≠0, the bearing ring  09  can be rotated, by utilization of the bearing ring rotary drive  13 , and the roll transport structure  03  can again be moved transversely of the roll longitudinal axis  07  until the axial offset “y” has been corrected. However, the rotary drive  13  for the bearing ring  09  can also be switched back on momentarily, and the roll support arm  22  on the side of the correct core position is caused to move first into the core. The material roll  18 , which is being supported by the roll transport structure  03 , with the actuated bearing ring  09 , is automatically rotated, until the second side of the core is also aligned. The other roll support arm  22  can then also be moved into the core. The further axle-loading process is implemented in a generally known manner. 
     When the new material roll  18  is in the clamped state, each of the first, position detection sensors  26  also measures the distance to the end surface  31  of the new material roll  18  adjacent it. Because the end surface  31  does not necessarily extend parallel to the adjacent roll support arm  22  of the roll support, as is illustrated by the dotted edge line in  FIG. 3 , the edge distance measurement Z 1  or Z 2  should be performed in the outer area of the end surface  31 , if at all possible, in other words near the uppermost material layer of the new material roll  18 . 
     As the desired value for the edge alignment, a machine-based standard distance from the end surface  32  of the expiring material roll  17  to the allocated roll support arm  16 , with a correct winding, can be preset. Any deviations, between the actual position of the end surface of the expiring material web and the assumed standard value are small near the center of the roll. With modified embodiments, however, the distance from the roll support arm  16  to the end surface  32  of the expiring material roll  17  can also be measured by a position-detecting element  33 , a second sensor  33 , in order to precisely determine the desired value for the new material roll  18 . 
     A comparison of the actual value and the desired value provides a positional deviation. When a positional deviation exists, the clamped new material roll  18  is moved in an axial direction until a position that corresponds with the desired value is reached. In this movement, the distance between the end surface  31  of the new material roll  18  and the first sensor  26  does not change. Instead, the roll support with the material roll  18  is moved, in order to compensate for the deviation from the desired value by adjusting the position of the new material roll  18 . 
     The new material roll  18  is displaced in an axial direction by a synchronous movement of the roll support arms  22  of the second roll support along a second motion axis  34 , as seen in  FIG. 3 , by the use of a positioning drive. Similarly, the roll support arms  16  of the first roll support can be adjusted along a first motion axis  36 , as also seen in  FIG. 3 , by the use of a separate, second positioning drive, in order to compensate for the existing edge offset. 
     The displacement of the new material roll  18 , to adjust the edge position, can be performed either via a continuous measurement and movement, or via a one-time measurement, a determination of the resultant deviation and a repositioning of the new material roll  18  by the determined amount of deviation. 
     A second sensor  33 , which corresponds to the first sensor  26 , is provided respectively on each of the roll support arms  16  of the first roll support, as may be seen in  FIG. 3 . When the roll change has been completed, this first roll support can take on another new material roll, and the distance to the end surface of this additional new material roll is determined again. 
     The same process can also be used, in a similar manner, for small material rolls  18 ′, with the exception of the now necessary, above-described, re-pivoting of the roll support arms  22 . 
     In  FIG. 4 , a further embodiment of a device for orienting the new material roll  18  in the roll changer  15 , in accordance with the present invention, is illustrated. The overall process is similar to the process already described in connection with  FIGS. 1-3 . A sensor or sensors  37 , such as, for example, distance sensors  37 , which are preferably attached to the roll supports  22  near the second motion axis  34 , measure the distances S 1  and S 2  from the longitudinal or peripheral edge  29  of the new material roll, as the transfer table  01  is being moved into the roll changer  15 . If the measured values for S 1  and S 2  are unequal, the material roll  18  is rotated until the measured values are equal. Afterward, the material roll  18  is moved fully into the roll changer  15 , and is loaded onto the axle. 
       FIG. 5  shows an embodiment of the present invention, and with a sensor, or sensors  38 , such as, for example, touch sensors  38 , which are attached to the roll support arms  22 . In this embodiment, no complicated systems for evaluating the measured values are necessary, because the alignment is implemented directly via a contact measurement. To orient the material roll  18  in this embodiment, first the roll support arms  22  are moved toward each other along the motion axis  34 , so that the longitudinal or peripheral edge  29  of the new material roll  18 , which is being moved in transversely to the longitudinal axis  19 , is able to strike or to contact the touch sensors  38 . If the material roll  18  lies obliquely to the motion axis  34 , as is indicated in  FIG. 5 , the leading part of the longitudinal or peripheral edge  29  will first touch the touch sensor  38  shown on the right roll support arm  22 . This touch sensor  38  can switch the bearing ring rotary drive  13  directly to clockwise rotation, until the other side of the material roll  18  also actuates the left touch sensor  38 , which stops the bearing ring rotary drive  13 . With this operation, the longitudinal axis  19  of the material roll  18  is now aligned parallel to the center axis  21  of the bearing journals  28 . 
     An even simpler variation of the present invention can be implemented when the touch sensor  38  that is first actuated, switches the bearing ring  09  to a free-running mode of operation, and the material roll  18  is rotated and oriented on the roll transport structure  03  by virtue of the movement of the transfer table  01  in the direction toward the roll changer, as indicated by arrow  24  of  FIG. 2 . When the second touch sensor  38  is touched, the bearing ring  09  and thereby also the roll transport structure  03  are stopped again. The roll support arms  22  are then moved apart from each other and into the axle-loading position and the transfer table  01  can be moved into position between the bearing journals  28 , where the further axle-loading process is now able to be implemented in a generally known manner. 
     To further illustrate the options for utilizing the sensors  26 ;  33 , which are provided for orienting the new material roll  18  in edge alignment, in  FIG. 6  the roll changer  15  is shown, again in a top plan view. The procedural for minimizing edge offset has already been specified in detail in connection with  FIG. 3 . The expiring material roll  17  is clamped between the roll support arms  16  of the first roll support. The new material roll  18  is in its position prior to clamping. In the clamping process, the roll support arms  22  of the second roll support are moved in respective opposing axial directions, with respect to each other, and both toward the roll center, until the bearing journals  28  become engaged in the core of the new material roll  18 , which material roll core is not specifically shown here. 
     The first sensor  26  is preferably fastened to the roll support arm  22  of the second roll support, and can be the same sensor that is used, as described above, for alignment of the roll. With this sensor  26 , in the clamped state of the new material roll  18  in the roll changer, the distance to the end surface  31  of the new material roll  18  is measured. The end surface  31  of the new material roll  18  does not necessarily extend parallel to the roll support arm  22  of the roll support, as is again indicated by the dashed edge line shown in  FIG. 6 . 
     To orient a material roll  18 , which is being delivered for loading onto the axle of a roll changer  15 , a device according to the following preferred embodiment can also be used, as is shown in  FIG. 7 : 
     An infeed unit  41  for a position detection element  42 , and especially for an alignment element  42 , such as, for example, an alignment cone  42  with a conical tip, is mounted on the roll support arms  16 ;  22  of the roll support. This alignment element  42  is located on the same radius as the bearing journals  27 ;  28 . 
     The material roll  18  is moved with the transfer table  01  to a defined axle-loading position, as based upon the previously determined diameter of the material roll  18 . 
     The roll support arms  16 ;  22  of the roll support are rotated to an aligned position, based upon the predetermined diameter of the new material roll  18 , with that aligned position being defined by the axle-loading position, minus the angle offset between the bearing journals  27 ;  28  and the alignment cone  42 . In this position, as shown in  FIG. 7   a , the alignment cone  42  is moved forward toward the core, in order to align the oblique material roll  18 . The alignment cone  42  is then retracted, as seen in  FIG. 7   b , and the roll support arms  27 ;  28  are rotated into the axle-loading position, as depicted in  FIG. 7   c . The aligned material roll  18  can then be loaded onto the axle. 
     The alignment cone  42  can be moved in the infeed unit  41  by the use of at least one positioning drive  43 , as shown schematically in  FIG. 7   a , such as, for example, an actuator cylinder, and especially a pneumatic cylinder, relative to the bearing journals  27 ;  28 , and can be moved especially linearly in the direction of a longitudinal axis of the adjacent bearing journal  27 ;  28 . 
     These alignment cones  42  are preferably positioned adjacent to all four bearing journals  27 ;  28 . 
     In  FIGS. 8 and 9 , a further embodiment of a roll changer  15 , in accordance with the present invention, is illustrated, in which embodiment the position detection elements are arranged on the side frame of the roll changer  15 . In this embodiment, the position detection elements are laser sensors  44 ,  45 , which are permanently attached to the roll changer. In connection with this embodiment, as depicted in  FIGS. 8 and 9 , the method for aligning the new material roll  18  or  18 ′, which is implemented using the depicted embodiment of the present invention, is also described. 
     As the material roll  18  or  18 ′ is being moved into a theoretical axle-loading position in the roll changer  15 , the edge of the material roll  18  or  18 ′, that is moving forward rapidly in the transport direction, is detected by the laser sensors  44 ,  45 . The theoretical axle-loading position for the transfer table is the position in which the material roll  18  or  18 ′ is aligned coaxially with the rotational axis of the bearing journals  27 ;  28 , and is arranged centrally on the transfer table. If the material roll  18  or  18 ′ is in an oblique position, an axial offset “z” of the material roll can be determined as the transfer table  01  is being moved into the roll changer  15 . 
     On one hand, the axial offset “z” can be determined through a determination of the position of the points M 3  and M 4 , as depicted in  FIG. 9 , that actuate the respectively allocated laser sensors  44 ,  45 . To accomplish this, a length measuring system  46 , with an absolute scale, is positioned on the track  06 . The length measuring system  46  determines the absolute position of the transfer table  01  on the track  06  as the point M 3  passes through the laser sensor  44 , and determines the position of the transfer table  01  on the track  06  as the point M 4  passes through the laser sensor  45  which has respectively been allocated to it. From these two known measurements, the axial offset “z” over the entire length of the new material roll  18  is determined through the use of a differential formation. The axial offset “z” is then divided in half and the theoretical axle-loading position for the transfer table  01  is corrected by the amount “z”/2, so that, depending upon the amount of the axial offset, the transfer table is either moved “z”/2 further into the roll changer, or is stopped “z”/2 in front of it. 
     The axial offset “z” can also be determined by measuring the time interval between detection of the point M 3  and of the point M 4 , and multiplying that determined time interval by a speed of movement of the transfer table. 
     With this preferred embodiment of the present invention, it can also be determined whether the material roll  18  or  18 ′ is arranged with its longitudinal axis  19 ,  19 ′ centered on the transfer table  01 . The absolute position of the transfer table  01  in the theoretical axle-loading position, when the material roll  18 ,  18 ′ is straight and centrally positioned, is known. If the roll lies on the transfer table in parallel offset, a parallel axial offset “v” must also be determined. To accomplish this determination, after the transfer table  01  has been moved into the theoretical axle-loading position for the new material roll  18 ,  18 ′, the actual position of the transfer table  01  is determined by the length measuring system  46 . If this deviates from the theoretical axle-loading position, the transfer table  01  must, in turn, be corrected by this amount “v”. 
     The calculation of the deviation in position of the material roll  18 ,  18 ′, both oblique position and additional axial offset, can be combined as the transfer table  01  is being moved into the roll changer  15 . 
     Once the transfer table  01  has reached the corrected axle-loading position, the bearing journals  27 ,  28  are introduced into the core. 
     In one preferred embodiment of the present invention, the bearing journals  27 ,  28  have centering tips  47 , as seen in  FIG. 9 , which centering tips  47  facilitate the introduction of the bearing journals  27 ,  28  into a core of an obliquely positioned roll such as a new material roll  18 . As the bearing journals  27 ,  28  are being introduced into the core of the material roll  18 ,  18 ′, the bearing ring  09  of the transfer table  01  is momentarily switched on, and the roll transport structure  03  is able to rotate to the necessary position as the bearing journals  27 ,  28  are being inserted into the core. The roll transport structure  03  is preferably connected to the transport carriage  02  via springs  48 , such that, following the axle-loading process, the structure is rotated back to the starting position by the springs  48 , which springs  48  are depicted schematically in  FIG. 9 . 
     If the determination of the axial offset “z” produces the result that the oblique position of the material roll  18 ,  18 ′ is greater than a maximum catch range for the centering tips  47 , an error signal is generated, and the axle-loading process is stopped. In this case, the material roll must either be repositioned on the transfer table, or the axle-loading process must be performed manually on the roll changer. 
     In  FIG. 10 , a preferred embodiment of a centering tip  47 , for use in the present invention, is shown, and such as can be used on bearing journals  27 ,  28  or on the alignment cone  42 .  FIG. 10   a ) shows a perspective view,  FIG. 10   b ) shows a view from below and  FIG. 10   c ) is a sectional representation that is taken along the line A-A in  FIG. 10   b ). 
     The centering tip  47  has a central bore hole  49  and also four continuous connecting bore holes  51 . On an upper side  52  of the centering tip  47 , and that faces the material roll, which is not specifically shown here, the centering tip  47  has a tapered surface shape  53  that extends to the peripheral edge of the centering tip  47 . The angle α of this tapered shape  53 , as seen in  FIG. 10 , in relation to the rotational axis of the bearing journals, preferably measures 35°. 
     The roll changer, in accordance with the present invention, is preferably arranged in a web-fed rotary printing press. 
     The processes of transporting the material roll into position and/or of orienting the roll and/or of loading the roll onto the axle are preferably implemented through the utilization of a shared control unit. This control unit, which is not specifically depicted, is preferably configured as a control panel of a printing press. 
     While preferred embodiments of methods and a device for orienting a material roll to be transported to a roll changer, in accordance with the present invention, 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 particular material on the roll, the overall operation of the roll changer, 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 scope of the appended claims.