Abstract:
A method for controlling elements for guiding sheet material and for controlling a surface for holding a sheet pile, which comprises registering, by a first sensor element, a lateral position of the sheet material and, based thereon, moving the surface for holding the sheet pile in a lateral direction, and controlling, via a sensor element for sensing a side edge of the sheet pile, independently of a first guide element, the lateral position of a further guide element, which is disposed on a side of the sheet pile, which is opposite to an aligning member for laterally aligning the sheet material and is assigned to an upper pile region; and a device for performing the method.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a method and a device for controlling elements which guide sheet material, such as are used, for example, in the feeder region of rotary printing machines for processing sheet material. 
     The published German Patent Document DE 298 01 061 U1 discloses the sensing of a sheet-pile edge for a sheet feeder. On a sheet feeder of a sheet processing machine, a sprung sensing roller is provided on a lateral edge of a sheet pile, and also a switch for registering the position of the sensing roller. The sensing roller is arranged on a lever that is pivotably connected to a holder which is guided format-adjustably in the sheet feeder. The lever is, in turn, braced or stressed by a leaf spring with respect to the holder, in a direction towards a zero position. The lever is pivotable to both sides from the zero position counter to the force of the leaf spring, it being possible for the pivoting movement of the lever in relation to adjustable tolerance limits to be registered by a switch. The leaf spring is firmly clamped into the holder and fixed laterally to the lever, however, it is fastened so as to be freely guided in the longitudinal direction. 
     The published European Patent Document EP 0 894 755 A1 discloses an aligning device for an automatic pile changer. Provided on a sheet-fed offset printing machine is a feeder having a non-stop device, also with a vertically adjustable residual pile carrier holding a residual pile, and also a pile support plate which is movable vertically and horizontally and holds a main sheet pile. Also provided are sensor devices, which are connected via an evaluation and control circuit to a drive for effecting a horizontal alignment of the pile support plate. What is sought to be achieved with such an aligning device is an exact alignment of the main pile with respect to the residual pile, in a structurally simple manner. For this purpose, the sensor devices are formed by a distance measuring system which is movable vertically via a lifting device, and by which, in a first position, the distance to the side surface of the residual pile and, in a second position located underneath, the distance to the side surface of the main pile can be registered and, by the evaluation and control circuit, the pile support plate can be moved via the drive in order that the two distance measured values are in agreement. 
     The published German Patent Document DE 198 16 181 A1 discloses a device for supplying sheets from a pile to a machine having a printing technology base. With this device, with little outlay of material and costs, lateral pile alignment of sheet material with increased accuracy and reliability is to be provided. A device for feeding sheet material includes a device for separating or singling the respective topmost sheet from the sheet pile, and also a device which conveys the separated sheet to the machine having a printing technology base. Also provided is a positioning device for the sheet pile, which permits controlled movement of the pile transversely with respect to the conveying direction, at least one feeler or detecting element being disposed in the region of a pile side edge that is provided, and also a feeler that reproduces the course of the pile side edge that is provided. 
     FIG. 1 diagrammatically shows a feeder for a sheet-processing machine according to the prior art, which has a sheet pile board holding a sheet pile, the pile board being movable in accordance with a sensor mechanism fitted to a first guide element. 
     At the feeder  1  of a machine for processing sheet material  5 , such as a rotary printing machine, for example, the sheet material  5  is drawn off the upper side of a sheet pile and guided in a conveying direction represented by the arrow  2 , in a conveying plane  3  corresponding to the plane of the drawing, to a front lay  9  aligning the leading edge of the sheet material  5 . Lateral alignment of the sheet material  5 , which may be formed, for example, of paper with lightweight or heavier-weight grammages and cardboard or pasteboard, is performed, in this regard, at a pulling device  10  provided at the operating side  8 . The pulling device  10 , which is arranged in a fixed location in relation to the conveying plane  3  of the sheet material  5 , can be configured, for example, as a pulling lay, a pulling rail or a pulling roller, and imparts a lateral pulling travel Z, also identified by reference numeral  11 , to the sheet material  5 . 
     Stop surfaces  14  and  18 , respectively, are provided on both sides, namely the drive side  7  and the operating side  8 , of the sheet pile containing the sheet material  5 . Each of the stop surfaces  14  and  18 , respectively, includes a sensor element  13  and  17 . In the case of the improvement in the feeder according to FIG. 1, which is disclosed in the prior art, the stop surface  18  provided on the operating side  8  is constructed in a fixed location. The pile gap F, also identified by reference numeral  12 , or the distance or spacing between the side edge of the sheet material  5  and the stop surface  18 , is fixedly prescribed and determines the position wherein the stop surface  18  is disposed. The position of the locally fixed stop surface  18  is determined from the difference between the pulling travel Z and the pile gap or distance F. 
     On the drive side  7 , a dedicated drive, for example, in the shape of an electric motor, is assigned to the positionable stop surface  14 . It is therefore possible for the controllable stop surface  14  to be controlled to a pile edge distance F,  12  in accordance with the course of the sheet pile edge. 
     A surface  15 , whereon a pile of the sheet material  5  is held, likewise includes a dedicated drive with which the surface that holds the sheet pile can be moved to both sides in the direction of the travel movement represented by the double-headed arrow  16 ,  50  that the pile board can be kept between the locally fixed stop surface  18  and the positionable stop  14  while maintaining a distance F that is kept constant to the greatest possible extent on both sides. 
     In sheet-processing rotary printing machines, sheets located on a paper sheet pile are separated by suitable systems and fed to the printing unit. The feeding is carried out over a given laterally offset amount, i.e., the pulling travel, which, for the purpose of lateral alignment of the sheet material before it runs into the first printing unit at front lays on the feed table, is impressed onto the individual sheet based upon the individual position of the sheet. The pulling travel should remain as constant as possible. In the case of laterally wavy or stepped sheet piles, this leads to lateral tracking by the personnel operating the sheet-processing machine, i.e., the pressmen, or lateral tracking by automation in the form, for example, of automatic pile centering. In this regard, the distance of the upper pile region from the guide element on the pulling side, i.e., the operating side, is kept constant. The guide elements are used for lateral guidance of the sheets previously loosened by air. In order to keep the pulling travel as constant as possible, the guide elements should be as close as possible to the pile. If the sheet width fluctuates, due to the sheet cutting tolerance, it is possible for jamming or an excessively large guide spacing to occur on the non-pulling side. For given printing material grammages, this can in turn lead to stoppages or to lateral scatter of the sheets in relation to the pulling travel. Furthermore, in the case of manual adjustment of the guide element on the non-pulling side, for example, when the automatic system is deactivated, the guide element can be moved into the pile. In this regard, the pile and the guide element can be damaged. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing corrective techniques heretofore known in the prior art, and also the indicated technical problem, it is an object of the invention to adapt the position of the guide elements guiding the sheet material to the position of the sheet pile, and to continuously monitor and possibly readjust the adaptation. 
     With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for controlling elements for guiding sheet material and for controlling a surface for holding a sheet pile, which comprises registering, by a first sensor element, a lateral position of the sheet material and, based thereon, moving the surface for holding the sheet pile in a lateral direction, and controlling, via a sensor element for sensing a side edge of the sheet pile, independently of a first guide element, the lateral position of a further guide element, which is disposed on a side of the sheet pile, and opposite to an aligning member for laterally aligning the sheet material, the further guide element being assigned to an upper pile region. 
     In accordance with another mode, the method invention includes controlling the further guide element on the non-pulling side to a constant distance from the lateral pile edge of the sheet pile. 
     In accordance with a further mode, the method invention includes controlling the distance from the pile edge of the sheet pile facing away from the aligning member for laterally aligning the sheet material. 
     In accordance with an added mode, the method invention includes assigning a separate control device, independently of the first-mentioned guide element, to the further guide element. 
     In accordance with an additional mode, the method invention includes controlling with the separate control device a drive for moving the further guide element on a crossmember/spindle. 
     In accordance with yet another mode, the method invention includes, with the sensor element associated with the further guide element, sensing without contact a pile edge facing away from an aligning member for laterally aligning the sheet material. 
     In accordance with yet a further mode, the method invention includes, with the sensor element, continuously sensing the pile edge facing away from the aligning member. 
     In accordance with yet an added mode, the method invention includes cooperating the first guide element assigned to a pulling-side pile edge, and the first sensor element which, via a control, controls the drive of the surface holding the sheet pile. 
     In accordance with yet an additional mode, the method invention includes providing the control on the input side thereof with printing-material specific and alignment-specific parameters, and activating the control so as to set the position of the first guide element via a drive, which is controlled via the control provided with the parameters. 
     In accordance with still another mode, the method invention includes deactivating an automation system by registering a distance or spacing via the sensor element, and switching off the drive to the further guide element when a distance between the pile edge and the further guide element falls below a critical prescribable distance. 
     In accordance with still a further mode, the method invention includes measuring the distances between a first sensor and a first pile side edge, on the one hand, and a second sensor and a second pile side edge, on the other hand, and also the position of actuating motors, and, by a control computer, determining the sheet width. 
     In accordance with a concomitant aspect of the invention, there is provided a device for performing a method for controlling elements for guiding sheet material and for controlling a surface member for holding a sheet pile, comprising a first sensor element for registering a lateral position of the sheet material and, based thereon, for moving the surface for holding the sheet pile in a lateral direction, a first guide element and a further guide element, and a sensor element for sensing a side edge of the sheet pile, independently of the first guide element, for controlling the lateral position of the further guide element disposed on a side of the sheet pile, which is opposite to an aligning member for laterally aligning the sheet material, the further guide element being assigned to an upper pile region. 
     The advantages that can be achieved with the improvement according to the invention are primarily to be seen in the fact that the guide element of the non-pulling side is controlled at a constant distance from the lateral pile edge of the non-pulling side. By continuous distance measurement between guide element and pile edge, and also by subsequent automatic movement of the guide element on the non-pulling side, this guide element is prevented from being moved too close to the pile or into the pile. This constitutes an additional safety aspect, for example, when the automation system is deactivated, i.e., the lateral control of the sheet pile is switched off, and protects the pile of printing material, which represents a considerable cost factor, against damage and therefore against non-usability. 
     In a further refinement of the idea upon which the invention is based, the further guide element arranged on the non-pulling side is controlled to a constant distance from a lateral pile edge. This distance depends upon the sheet format that can be processed and is readjusted based upon the course of the pile edge on the non-pulling side. During the sensing required for the control of the guide element on the non-pulling side, the lateral pile edge of the sheet pile which is sensed is the edge of the sheet pile facing away from the aligning member for the lateral alignment of the sheet material. Thus, the position of the further guide element, i.e., of the guide element arranged on the non-pulling side, which in each case depends upon the course of the pile edge, may be guided to follow the critical pile edge of the sheet pile directly, in real time and without requiring any further conversion equipment. 
     In order to decouple the control of the further guide element from that of the first guide element provided in the upper pile region, an independent, separate control device is provided. The independent, separate control device is not incorporated into the automatic control of the first guide element nor the control of the lateral position of the platform that holds the sheet pile, so that, even when the automatic system for tracking the sheet pile is deactivated, a safeguard is provided against collision on the non-pulling side of the sheet pile, by sensing the pile edge on the non-pulling side of the sheet pile. Via the separate control, which controls the lateral position of the further guide element held on the upper side of the sheet pile, the position on a crossmember can be moved laterally via a drive, preferably an electric motor drive, which drives only the further guide element. 
     The sensor mechanism associated with the further guide element senses without contact the pile edge facing away from the aligning member, for example, a pulling lay or a pulling roller, on the surface of the feeding table for the sheet material, for the lateral alignment of the sheet material. The non-contact sensing is performed in order to determine the current respective distance or spacing of the sheet pile edge from the stop surface which is formed on the further guide element. Depending upon the course of the pile edge on the side of the sheet pile, which faces away from the aligning member for the lateral alignment of the sheet material, the drive of the further guide element on the crossmember is activated, it being possible for the activation to be performed by an electric motor, for example, which drives a threaded spindle which, in turn, moves the further guide element towards the pile edge or away from the latter transversely with respect to the conveying direction in the upper guide pile region. In order to ensure permanent monitoring of the sheet pile edge on the non-pulling side, for example, when the automatic tracking of the platform holding the sheet pile is deactivated, the control of the further guide element is continuously active, i.e., is accordingly not switched off when the sheet pile control is deactivated. 
     The first guide element, which is arranged on the side of the sheet pile whereon the aligning member for the lateral alignment of the sheet material is also accommodated, is controlled via a sensor mechanism which, via a controller, controls the drive of the surface that holds the sheet pile in the lateral direction. Therefore, on the pulling side of the sheet pile, the tracking thereof to a given desired lateral distance between the sheet pile edge on the pulling side and the first guide element can be carried out, independently of the control loop of the further guide element at the sheet pile edge on the non-pulling side. 
     When the control is activated, the position of the first guide element is set via a drive which is controlled via a control which, on the input side, is provided with printing-material specific and alignment-specific parameters. Such parameters may be, for example, the respective printing material format to be processed, also the distance at which the first guide element is to be controlled to the pile edge on the 
     Pulling side of the sheet pile. When the automation system is deactivated, i.e., the control of the first guide element for readjusting the surface that holds the sheet pile, by continuously registering the distance between the sheet pile edge on the non-pulling and the further guide element via the sensor mechanism when it falls below a critical distance or spacing between the pile edge and the further guide element, is switched off, the drive of the further guide element is stopped. Therefore, in the case of manual actions by the printers, who previously have switched off the automatic control of the sheet pile position based upon a first guide element in the upper pile region, the opposite side of the sheet pile is preserved against damage during actions which are manually performed. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a method and device for controlling sheet-material guiding elements, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagrammatic plan view, partly in section, of a feeder for a sheet-processing machine, with a controlled pile board position and a controlled lateral stop surface; and 
     FIG. 2 is a diagrammatic side elevational view of the device according to the invention for distance control of guide elements which are positionable beside a previously loosened upper pile region. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2 reveals in detail the improvement according to the invention of the instant application for distance control of guide elements positioned beside the previously loosened upper pile region. 
     In the improvement according to the invention of the instant application, which is reproduced in a side elevational view in FIG. 2, a sheet pile  34  is held on a surface  15 . An upper region  35  of the sheet pile  34  of sheet material is previously loosened by the entry of blown air. The entry of blown air in the upper pile region  35  achieves secure and reliable separation or singling of the individual copies of the sheet material  5 . The separated copies are conveyed in the conveying direction  2  in a conveying plane extending perpendicularly to the plane of the drawing, are aligned at front lays  9  (not shown in FIG. 2) and then, accelerated to machine speed, are conveyed into the printing units of a sheet-processing machine. 
     Above the upper pile region  35 , two crossmembers or traverses  42  and  43 , respectively, are disposed extending over the width of the sheet pile  34 . The crossmembers  42  and  43  are constructed as guide/threaded spindles, and to each of the crossmembers  42  and  43 , respectively, there are assigned a dedicated drive  31  on the operating side  7  of the sheet pile  34 . The upper crossmember  42  serves for driving a first guide element  25  on the operating side  8  of the sheet pile  34 . The first guide element  25  is guided transversely with respect to the pile direction  34  on the lower crossmember  43  and is provided with the drive thereof by the threaded section formed on the upper crossmember  42 . Both crossmembers  42  and  43  are mounted in mounting supports  30  on the operating side  8  and the drive side  7 , respectively, in the feeder region  1 , and are secured against horizontal displacement by axial bearings. 
     A further guide element  24 , assigned to the upper region  35  of the sheet pile  34 , is guided on the upper crossmember  42  and, by a threaded section formed on the lower crossmember  43 , is moved in the lateral direction relative to the sheet pile  34 , in accordance with the double-headed arrow shown. A sensor element  26  and  27 , respectively, is assigned to the first guide element  25  and the further guide element  24 . The sensor elements  26  and  27 , respectively, can advantageously be secured to the outer side of the guide elements  25  and  24 , respectively, and can be constructed so that the sensor elements  26  and  27 , respectively, extend in the direction towards pile edges  28  and  29 , respectively, on the drive side  7  and the operating side  8 , respectively, of the sheet pile  34 . The sensor elements  26  and  27  are preferably of non-contact or contactless construction, and register the current lateral distances or spacings  32  and  33 , respectively, between the sensor elements  26  and  27 , respectively, and the side edges  28  and  29 , respectively, of the sheet pile  34 . 
     The sensor element  27 , which is assigned to the first guide element  25 , is connected to a control  40  for the surface of the board  15  that supports or holds the sheet pile  34 . The surface board  15  that supports the sheet pile  34  is movable in the lateral direction represented by the arrow  39 . To this end, the surface of the board  15  that holds the sheet pile  34  is mounted on mounting supports  37  which absorb the load of the sheet pile  34 . In addition, the surface of the board  15  is movable laterally in the direction of the arrows  39  by a drive  38  assigned to the surface board  15 . The extent of the lateral movement travel  39  depends upon the course of the pile edge  29  on the operating side  8  of the feeder  1 . Depending upon the course of the pile edge  29  of the sheet pile  34 , the surface of the board  15  that holds the sheet pile  34  is controlled in accordance with the current pile edge distance or spacing  33  between the pile edge  29  and the sensor element  27 . 
     The sensor element  26 , which is assigned to the further guide element  24  and which senses the pile edge  28  of the sheet pile  34 , preferably without contact and continuously, is connected to a separate control device  41 . The control device  41  connected to the sensor element  26  on the drive side  7  controls the drive  31 , which acts upon the crossmember  43  serving as a drive spindle for the further guide element  24 . Accordingly, the possibility, therefore, exists of controlling the further guide element  24  in relation to the lateral position thereof at the upper region  35  of the sheet pile  34 , independently of the first guide element  25 . 
     The drive  31 , which acts upon the upper crossmember  42  formed partly as a threaded spindle, is activated via a control  20 . On the input side, the control  20  has available thereto information  21  about the pulling travel, and also information  22  about the printing material format to be processed. In addition, the center offset  23  can be input to the control device  20 . From this information, on the output side of the controller, an activation signal for the drive  31  of the upper crossmember  42 , formed partly as a threaded spindle, is determined, which moves the first guide element  25  while maintaining a given prescribable distance or spacing from the pile side edge  29 . This first adjustment can be made within the context of presetting, i.e., when setting up a new job. By the sensor mechanism  27  provided on the first guide element  25 , during production or continuous printing, i.e., continuous separation or singling of copies of sheet material  5  in the upper region  25  of the sheet pile  34 , the control unit  40  for the pile support board  15  tracks the lateral offset  39  of the latter in accordance with the course of the pile edge  29  facing the operating side  8 . 
     Independently thereof, the drive  31  which acts upon the lower crossmember  43  is controlled via the sensor element  26  connected to the further guide element  24 . Via the drive  41 , the further guide element  24  can be guided so as to follow the course of the pile side edge  28  facing the drive side  7 . The tracking of the further guide element  24  to the pile side edge  28 , i.e., on the non-pulling side of the sheet pile  34 , is performed by virtue of the independent control loop  41 ,  31 , independently of the tracking of the first guide element  25  on the pile edge  29  on the operating side of the sheet pile  34 . Due to the decoupling of the control loop  26 ,  41 ,  31  for the further guide element  24 , the latter can be controlled independently of the control loop  27 ,  40 ,  38 , so that, in the event of deactivation of the automatic pile tracking, i.e., of the controller  40 , or manual adjustment of the first guide element  25 , assurance is provided that the control loop  41  controlling the lateral position of the further guide element  24  remains activated at all times and prevents the occurrence of any collision between the upper region  35  of the sheet pile  34  and the further guide element  24 . This is required in particular when the pile tracking control is deactivated by the pressman when adjustments have to be performed manually. The independent control of the lateral position of the further guide element  24  in relation to the upper region  35  of the sheet pile  34  also takes into account that the further guide element  24  on the drive side  7  of the feeder  1  is difficult to access. Using the separate control loop proposed according to the invention for the further guide element  24 , manual intervention of the pressman in order to prevent a collision between the further guide element  24  and the previously loosened upper region  35  of the sheet pile  34  is no longer required. 
     The sensors  26  and  27 , respectively, which sense the pile edges  28  and  29 , respectively, on the drive side  7  and the operating side  8 , respectively, preferably register the course of the pile edges  28  and  29  without contact. During the sensing of the pile edges  28  and  29  by the sensors  26  and  27 , respectively, assurance is provided that this sensing is performed continuously. This applies in particular to sensing the drive-side, i.e., the non-pulling-side pile edge  28  of the sheet pile  34  of the sheet material  5 . In the event of a deactivation of the automatic tracking, i.e., the activated automation system, the continuous distance measurement of the distance  32  between the sensor element  26  on the drive side  7  and the drive-side pile edge  28  prevents the further guide element  24  from coming too close to the upper region  35  of the sheet pile  34  or from moving into the pile. In the event that the distance between the drive-side pile side  7  and the sensor element  26  falls below a given prescribable distance or spacing  32  during a motor-driven or manual adjustment, the drive  31  which moves the further guide element  24  laterally is switched off, so that damage to the pile side edges on the drive side  7  of the sheet pile  34  due to an inadvertent movement of a further guide element  24 , which guides the printing material  5  laterally, the inadvertent movement being into the region of the sheet pile  34 , is avoided. 
     From the distance determined between the sensor  26  and the pile side edge  28 , on the one hand, and the sensor  27  and the pile side edge  29 , on the other hand, and also the position of the actuating motors  31 , the approximate sheet width can be calculated by the control computer  41 . 
     This value can be passed on by the control computer  41  to following sheet guidance or processing devices in order to set them with regard to the width of the material to be processed.