Abstract:
An apparatus comprising two lateral guide devices guiding the paper web at the longitudinal edges of the endless paper web, and a deflection means is provided. With the aid of the deflector the paper web is deflected at least once from its direction of movement to increase the stiffness of the paper web while the paper web is moving between the lateral guide devices. Because of that, the paper web is prevented from ascending the lateral guide devices and a damage to the paper web is avoided when the paper web comes into lateral contact with the lateral guide device.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an apparatus for guiding an endless paper web and in particular to an apparatus for guiding an endless paper web without making use of perforated edges or transport pins to a subsequent paper processing means. 
     BACKGROUND OF THE INVENTION AND DESCRIPTION OF THE PRIOR ART 
     The present invention relates to an apparatus for guiding an endless paper web and in particular to an apparatus for guiding an endless paper web without making use of perforated edges or transport pins to a subsequent paper processing means. 
     In the prior art various apparatuses for guiding an endless paper web e.g. to a paper processing system are known. For achieving the straightest possible movement of the paper e.g. through a paper cutter or a printer, one method of implementing a paper guide means is the use of so-called traction means in the case of which transport holes punched into the paper web on both sides thereof are engaged by pins for transporting the paper. 
     One disadvantage of this paper guide means is to be seen in the fact that, for providing the perforated edges, the paper web must first be taken to a ready-to-use manufacturing apparatus by the producer before it can be supplied to the final consumer. In addition, the transport holes are frequently cut off from the lateral edges of the paper web for optical or other reasons in the means used for further processing, and this entails, in turn, an unnecessary consumption of paper and unnecessary waste paper and it necessitates an edge cutting means. 
     In the case of a further apparatus for guiding an endless paper web known on the prior art, the straight movement of the paper web is achieved by means of web-edge control making use of adjustable guide and transport rolls. 
     A paper guide means of this kind requires a very complicated technical design with adjustable guide and transport rolls; in addition, it is very complicated to carry out the adjustments for guiding a paper web of the respective type of paper. 
     In the prior art, an apparatus is additionally known in the case of which a paper guide means, which is described in detail in FIG.  6 . Comprises a trough structure  100  with a concave or convex surface  102  and shoulders  104 . The shoulders  104  are provided for engagement with opposed edges of a paper web  106 . The direct distance  108  between the shoulders  104  on both sides of the trough structure  100  is smaller than a width  110  of the paper web  106  when flat. The trough structure  100  has the effect that the paper web  106  is deformed with regard to its width  110  so that the distance  108  between edges along the longitudinal sides of the paper web  106  in the trough structure  100  is smaller than the width  110  between the edges of the trough structure. When the apparatus is in use, the paper web  106  moves from an entrance end  112  to an exit end  114  through the trough structure  100 . The shoulders  104  engage the paper edged so that the paper is help in the trough structure and guided along a straight line. 
     The paper web  106  moves through the trough structure  100  to a flat surface  116 . This flat surface  116  extends from the concave surface  102  (support structure) of the exit end  114  of the trough structure  100  to the straightening plows  118 . The flat surface  116  is additionally provided with a central opening  120 . The opening  120  has arranged therein the driving roll  122 . The driving roll  122  is arranged in the opening  120  in a vertical plane in such a way that an outer rubber surface  124  of the driving roll  122  is located slightly above the flat surface  116 . The outer layer  124  of the driving roll  122  engages the lower surface of the paper web  106  as soon as this paper web  106  moves over the flat surface  116  and conveys the paper web  106  by means of the rotation of the driving roll  122 . 
     The straightening plows  118  are provided at the end of the flat surface  116  opposite the trough structure  100 , as can be seen in FIG.  6 . The straightening plows  118  comprise an upper lip  124  and a lower lip  126 . In this arrangement, a pressure roll  128  is used for applying a pressure on a paper web passing between the pressure roll  106  will be maintained in contact with the driving roll  122 . 
     The direction of movement of the paper web  106  through the trough structure  100  is indicated by the arrow  130  in FIG.  6 . 
     Due to the fact that the driving roll  122  is arranged such that it projects through the opening  120  above the flat surface  116 , an axial displaceability of the driving roll  122  is not possible. 
     An apparatus of this type is known e.g. from U.S. Pat. No. 5,213,246, which achieves paper guidance by means of a trough structure in which the paper web flows, the trough structure being formed in one piece. Due to the structural design of this trough structure, a separate trough structure is required for each paper web width. In addition, when the paper web running through the trough structure is very broad and thin, only a very slight increase in the stiffness of the paper web can be reckoned with. 
     In view of the above-mentioned facts, known paper transport means are only capable of guiding paper webs having a specific width and paper thickness or it is necessary to use either so-called traction means or a complicated web-edge control for guaranteeing that the paper web moves along a straight path e.g. to a paper processing system. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide an apparatus for guiding an endless paper web which is capable of handling the paper web independently of its width and thickness without using any traction means or web-edge control. 
     The present invention is an apparatus for guiding an endless paper web having: 
     two lateral guide devices guiding the paper web at the longitudinal edges thereof; 
     a deflector with the aid of which the paper web is deflected at least once from its direction of movement while it is moving between the lateral guide devices; and 
     a first transport roll on a drivable shaft and a second transport roll for applying a feed force to the paper web passing between the first and the second transport roll. 
     The present invention is based on the finding that an increase in the stiffness of the paper web is achieved by vertically deflecting the paper web from the direction of movement, whereby the paper web will be prevented from ascending the lateral guide means and whereby damage to the paper web will be avoided when the paper web comes into lateral contact with the lateral guide means. 
     An advantage of the present invention is to be seen in the fact that paper costs can be reduced essentially, since the paper webs can be used with an unperforated edge thus avoiding the necessity of laterally cutting off the transport holes for optical or other reasons in the means used for further processing; this avoids an unnecessary consumption of paper and unnecessary waste paper, and additional edge cutting means can be dispensed with. 
     According to a preferred embodiment of the present invention, a wave-shaped path of movement or rather a wave-shaped deflection of the paper web from its direction of movement is achieved by means of a plurality of round bars between which the paper web passes. Since the deflection of the paper web can be adjusted to different paper web widths, paper thicknesses and strengths by adjusting one of the round bars and the distance of the lateral guide means, the apparatus for guiding an endless paper web is capable of handling paper webs with arbitrary paper web widths, paper thicknesses and strengths, respectively. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, preferred embodiments of the present invention will be explained in detail making reference to the drawings enclosed, in which: 
     FIG. 1 shows a perspective view of an embodiment of the apparatus according to the present invention for guiding an endless paper web comprising a first transport roll arrangement; 
     FIG. 2 a  shows a perspective view of an alternative transport roll arrangement; 
     FIG. 2 b  shows a perspective view of an alternative arrangement for pretensioning a transport roll arrangement; 
     FIG. 3 shows a sectional side view of the apparatus for guiding an endless paper web provided with a mark reader; 
     FIG. 4 shows a representation of the mark reader shown in FIG. 3; 
     FIG. 5 shows a sectional side view of the apparatus for guiding an endless paper web with an alternative arrangement of the paper guide bars and of the mark reader; 
     FIG. 6 shows a paper guide means according to the prior art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, preferred embodiments of the apparatus according to the present invention will be described in detail on the basis of FIGS. 1 to  5 . 
     FIG. 1 shows a first preferred embodiment of an apparatus according to the present invention used for guiding an endless paper web. A plurality of round bars  10 ,  12 ,  14  is supported between two side walls  16  (only one of these walls is, however, shown). Also two lateral guide means  18 ,  20  are arranged between the two side walls  16 ; these lateral guide means  18 ,  20  are mounted on a transverse strip  22  and adapted to be axially displaced relative thereto. The transverse strip  22  has additionally arranged thereon a plurality of guide strips  24 . 
     In FIG. 1, a first  26  and a second  28  transport roll are additionally shown. The first transport roll  26  is fixed to a shaft  30  such that it is secured against rotation relative thereto; this shaft  30  is rotatable about a shaft axis  34  in a direction of rotation indicated by the arrow  32 . A driving pulley  36  of the transport roll  26  is connected via a form-fit driving belt  38  to a driving pulley  40  attached to a shaft  42  of a feed motor  44 . 
     An L-shaped bearing block  46  is axially displaceable with regard to a central axis  48  of a shaft  50 , a biasing spring  52  being attached to a lower portion of the L-shaped bearing block  46 . In a section  54  extending at right angles to the L-shaped bearing block  46 , a shaft  56  is arranged, which is connected to a guide means  58  for the second transport roll  28 , the transport roll  28  rotating about an axis  59  arranged in this guide means  58 . 
     The shaft  56  has provided thereon two pins  62  which extend at right angles to a central axis  60  of the shaft  56 , each pin  62  having a spring force applied thereto by a respective one of two springs  64 . The central axis  60  extends at right angles to the axis of rotation  34  of the transport roll  26 . The pivoting range of the second transport roll  28  about the central axis  60  is determined by means of the springs  64 , as shown by the double arrow  66  in FIG.  1 . 
     In FIG. 1 an endless paper web  68  is additionally shown, which runs through the apparatus for guiding an endless paper web in the direction of movement shown by the arrow  70  and which has optionally provided thereon read marks  72 , if such read marks are required for further processing the endless paper web  68 . 
     In the following, the technical mode of operation of the apparatus used for guiding an endless paper web will be described in detail making reference to FIG.  1 . To simplify matters, the apparatus used for guiding an endless paper web will be referred to as paper transport means in the following. 
     The paper web  68  is supplied to the paper transport means from a stack, a reel or on-line from a printer (not shown). The paper web  68 , which is deflected by means of at least one of the round bars  10 ,  12 ,  14 , is passed in a wave shape through the round bars  10 ,  12 ,  14  which are arranged transversely to the direction of movement of the paper web  68  and which are supported between the two side walls  16  (only one of these walls is shown). 
     The two lateral guide means  16 ,  18  for the paper web  68  are secured to a transverse strip  22  and they are axially displaceable relative to said transverse strip  22 . The laterally adjustable lateral guide means  18 ,  20  are axially adjusted such that they are spaced at a distance from one another which is only slightly larger than the paper web  68 . Due to the wave-shaped path of movement through the round bars  10 ,  12 ,  14 , the paper web  68  has imparted thereto a degree of stiffness which is so high that, if the paper web comes into lateral contact with the lateral guide means  18 ,  20 , it will not be damaged and it will be prevented from ascending these lateral guide means  18 ,  20 . One or a plurality of the round bars  10 ,  12 ,  14 , i.e. in the case of three round bars preferably the central round bar  12 , is/are, moreover, vertically adjustable relative to the paper web  68  in such a way that the magnitude of the paper wave amplitude can be adjusted in a range from 0 (cf. also FIG. 4) up to several millimeters, whereby the resultant stiffness of different kinds of paper can be adjusted. 
     A paper wave amplitude of 0 is preferably adjusted when a new endless paper web is “threaded” into the apparatus for guiding an endless paper web or when the strength of the paper web  68  running through the apparatus is already so high that no increase in strength or only a minor increase in strength is necessary for straight guidance of the paper web  68 . 
     After a wave-shaped passage through the guide bars  10 ,  12 ,  14 , the paper web  68  is supplied to the pair of transport rolls  26 ,  28  via the lateral guide means  18 ,  20  secured to a transverse strip  22 . The guide strips  24  on which the paper web rests can be implemented in the form of elongate ribs, as shown in FIG. 1, paper-guiding supports or paper-supporting surfaces of an arbitrary shape being imaginable for the paper web  68 . 
     By means of the first and second transport rolls  26 ,  28 , a feed force is applied to the paper web  68 , the first transport roll  26  being fixed to the shaft  30  such that it is secured against rotation relative thereto and driven via the form-fit driving belt  38  by means of the feed motor  44 . 
     The second transport roll  28  is attached to the L-shaped bearing block  46  which is axially displaceable with regard to the axis  48  of the rod  50 . By means of the biasing spring  52 , which, as can be seen in FIG. 1, is arranged on the L-shaped bearing block  46 , the second transport roll  28  is pretensioned relative to the first transport roll  26 , i.e. the transport roll  28  is pressed onto the transport roll  26  with a certain spring force. The second transport roll  28  is additionally arranged such that it is rotatable about the axis of rotation  60  in the bearing block  46 , the axis of rotation  60  being positioned perpendicular to and centrally to the axis  34  about which the shaft  30  rotates. By means of the two springs  64  applying a spring force to the two pins  62  which are arranged perpendicularly on the shaft  56  and parallel to the axis  59 , the rotary position or pivoting range of the second transport roll  28  can be adjusted for a pendulum motion when the paper web  68  is being aligned. 
     The lower transport roll  26  of the transport roll arrangement consists preferably of steel and has an exact diameter so as to guarantee that deformations and temperature expansions, respectively, occurring in the case of other materials to a higher degree do not have a negative influence on a constant transport path of the paper web  68  per revolution of the drive. The upper transport roll  28  of the transport roll arrangement is provided with an elastomeric coating having a high coefficient of friction so as to avoid a possibly occurring slip between the upper transport roll  28  and the endless paper web  68 . 
     The upper transport roll  28 , which is provided with an elastomeric coating having a high coefficient of friction, is pretensioned relative to the lower transport roll  26  via the L-shaped bearing block  46  by means of the biasing spring  52 . The pair of transport rolls  26 ,  28  is axially displaceable on the shafts  30  and  46 , respectively, so that the pair of transport rolls  26 ,  28  can be positioned centrally to the paper web. The upper transport roll  28 , which serves as a thrust roll, is additionally rotatably supported in the L-shaped bearing block  46 , the axis of rotation  60  of this upper transport roll  28  extending perpendicular to and centrally to the axis of rotation  32  of the roll  26 . With the aid of the adjustable compression springs  64 , which act on the axis of rotation  60  via the two pins  62  on the shaft  58 , the axis of movement of the roll  28  is caused to orient itself automatically parallel to the roll  26 . When a paper web  68  moving at an oblique angle is adjusted by means of the lateral guide strips  18 ,  20  to the desired position parallel to the middle of the apparatus, i.e. to a position where the paper web  68  is oriented parallel to the lateral guide strips  18 ,  20 , the roll  28  is additionally able to carry out the associated pendulum motion when the paper web is being aligned. 
     In the following, elements which are identically arranged and implemented in FIGS. 1 to  5 , are designated by identical reference numerals. 
     FIG. 2 a  shows an alternative transport roll arrangement for adjusting the rotary position of the transport roll  28 . Since in the case of very thin paper, a forced deflection of the paper web  68  is not possible, FIG. 2 shows an additional embodiment in the case of which the axis of rotation  60  of the roll  28  can be oriented precisely relative to the lateral guide means  18 ,  20  and secured in position via adjustable clamping screws  74 , i.e. by rotating the screw heads  75 . This prevents the transport roll  28  from carrying out the above-described pendulum motion by means of which a paper web  68  moving at an oblique angle is aligned parallel to the lateral guide means  18 ,  20 , whereby a paper web consisting of a very thin and sensitive paper is prevented from being damaged, i.e. from crumpling or even tearing. 
     In contrast to the embodiment shown in FIG. 1 where two springs  64  are used, the adjustment of the position of the transport roll  28  relative to the axis  60 , i.e. of the two pins  62  relative to the pivoting range  66  of the transport roll  28 , can be accomplished by means of the two clamping screws  74 . Preferably, the axis of rotation  59 , about which the transport roll  28  rotates, is oriented parallel to the axis of rotation  32  of the transport roll  26 . As for the rest, the mode of operation of the transport roll arrangement according to FIG. 2 is identical with that of the transport roll arrangement according to FIG.  1 . 
     FIG. 2 b  shows an alternative arrangement for pretensioning the bearing block  46  and, consequently, the upper transport roll  28  relative to the lower transport roll  26 . 
     In this embodiment the bearing block  46  is connected to the shaft  50  such that it is secured against rotation relative thereto; the bearing block  46  can additionally be axially displaceable relative to the shaft  50 . In the vicinity of the two ends of the shaft  50 , two connecting struts  75   a  are arranged whose lower portions  75   b  are provided with an opening for accommodating the shaft  50 , the lower portions  75   b  of the connecting struts  75   a  being connected to the shaft  50  such that they are secured against rotation relative thereto. The upper portions of the connecting struts  75   a  are arranged in opposed relationship with two L-shaped stop members  75   c  provided with an opening  75   d  so that the L-shaped stop members  75   c  can be secured to a support structure (not shown). Between the opposed connecting struts  75   a  and L-shaped stop members  75   c , a respective compression spring  75   e  is provided. 
     By means of these compression springs  75   e  a spring force can be applied to the upper portion of the connecting struts  75   a , whereby a pivotal movement of the connecting strut  75   a  and, consequently, a rotation of the shaft  50  can be caused; by means of this rotation, the upper transport roll  28  arranged on the bearing block  46  is pretensioned relative to the lower transport roll  26 . 
     FIGS. 3 and 4 show a paper transport means having a reader  76  arranged thereon, which is provided on the side facing the paper web  68  preferably above the adjustable round bar  12 ; in correspondence with the round bar  12  which is adapted to be adjusted at right angles to the direction of movement of the paper web  68 , the reader  76  is adjustable by means of an adjustment device  78  relative to the direction of adjustment indicated by the double arrow  80 . The reader  76  detects the marks  72  on the paper web  68  preferably with the aid of optical means  77 . The adjustment device  78  is used for adjusting the vertical position of the round bar  12 , and, consequently, the deflection of the paper web  68 , as well as the position of the reader  76 . 
     In FIG. 4, the position of the round bar  12  has been adjusted such that the paper web  68  is not subjected to any deflection. The different positions of the adjustable round bar  12  that can be adjusted and, consequently, the deflection of the paper web  68  are provided for the purpose of adapting the deflection of the paper web  68  to the speed at which the paper web  68  runs through the paper guide means, with due regard to the strength of the paper, the stiffness of the paper, the stressability and the thickness of the paper. 
     By simultaneously adjusting the vertical position  80  of the reader  76  and the adjustable round bar  12 , a constant predefined distance is obtained between the paper web  68  running over the adjustable round bar  12  and the reader  76  by means of which the read marks  72  required for format length control, e.g. in paper cutting units, can be detected and read, respectively. The arrangement of the guide bars  10 ,  12 ,  14  and of the reader  76  can be adjusted such that it varies between a maximum deflection of the paper web  68  and a minimum deflection or no deflection at all of the paper web  68  (cf. FIG.  4 ), as has already been described above. 
     FIG. 5 shows a sectional side view of the paper transport means with an alternative arrangement of the paper guide bars  10 ,  12 ,  14  and of the mark reader  76 . FIG. 5 shows an arrangement of the reader  76  and of the adjustment device  78  relative to the direction of movement of the paper web  68  which is mirror-symmetrical with respect to the arrangement show in FIG.  4 . This variant of arranging the reader  76 , the adjustment device  78  and the round bars  10 ,  12 ,  14  is used when the marks  72  to be detected by the reader  76  are located on the paper web side facing the transport roll  28 . 
     In the case of a further arrangement of the reader  76  and of the round bars  10 ,  12 ,  14 , the readers  76  are arranged on both sides of the paper web on the respective side facing the paper web  68  above an arbitrary round bar  10 ,  12 ,  14 , whereby the marks  72  to be detected can be provided on an arbitrary side of the paper web  68  and the reading of the read marks  72  is reliably guaranteed. The provision of the readers  76  is, however, not limited to an arrangement in which these readers  76  are necessarily arranged above the adjustable round bar  12 , but they can also be located above another round bar  10 ,  12 ,  14 . 
     When the apparatus according to the present invention is used e.g. in cutting machines requiring a very precise detection of the paper feed and of the position of the paper, respectively, it must be guaranteed that the paper web is guided as exactly as possible and that the instantaneous position of the paper web  68  is therefore detected and controlled as precisely as possible. Hence, minor slip and format length corrections are carried out by means of a correction control in the case of which the position of e.g. the cross-cutter or of some other paper processing means and the paper feed can be compared and changed, if necessary. For this kind of control, the read marks  72  are required at regular intervals on the paper web  68 ; during passage of the paper web  68 , these read marks  72  are detected by means of the reader  76  and transmitted to an evaluation means (not shown) in which the positions of the detected read marks  72  are evaluated and further processed in a suitable manner. Making use of the detected positions of the read marks  72 , the evaluations means calculates the necessary paper feed and controls the transport roll arrangement and the transport roll  26 , respectively, on the basis of the detected values, whereby the feed of the endless paper web  68  is adjusted precisely and correct further processing of the endless paper web  68  is guaranteed. 
     In contrast to the three round bars  10 ,  12 ,  14  which are shown in the drawing and only one of which, viz. the round bar  12 , is vertically adjustable in position, an arbitrary number of round bars can be provided in the apparatus for guiding an endless paper web according to the present invention; it is also possible to use a plurality of adjustable round bars so as to permit the paper web  68  to be deflected more than once. Furthermore, it is also possible to arrange a plurality of corresponding deflection arrangements, which consist of a plurality of round bars or which are implemented in accordance with the first preferred embodiment, at predefined intervals so as to permit a straight and correct guidance of an endless paper web also over distances of greater length. 
     In addition, the shape of the round bars provided for the deflection of the paper web  68  can be modified in comparison with the shape shown in FIG. 1 to  5 . A plurality of rolls can, for example, be provided, which are arranged axially and rotatably on the round bars at regular intervals, two outer rolls being arranged such that they are flush with the lateral guide means and the lateral guide strips, respectively, so that the edges of the paper web  68  extend perpendicularly to the lateral guide means, i.e. so that these edges only move perpendicularly into contact with the lateral guide means. This has the effect that the size of the contact surface on which the endless paper web  68  moves over the respective rolls is reduced. 
     Furthermore, the reader  76  can be arranged at a location other than the position above a round bar, e.g. the adjustable round bar; it must, however, be guaranteed that the distance between the paper web  68  and the respective reader  76  is kept constant so as to guarantee that the read marks  72  arranged on the paper web  68  are read precisely and without errors.