Abstract:
A corrugator single facer of the type utilizing a large diameter bonding and corrugating roll and a small diameter corrugating roll is driven without direct drive applied to either corrugating roll. Instead, the pressure belt arrangement which supports the lower corrugating roll to provide the nipping force includes a series of driven supporting pressure belts that are loaded against the lower corrugating roll and which transmit rotational movement thereto and through the nip to the large diameter bonding roll.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention pertains to a single facer apparatus for forming a single face web of corrugated paperboard. More particularly, the invention relates to a corrugating roll assembly comprising a large diameter corrugating roll (i.e. a bonding roll) and a small diameter corrugating roll in which the support arrangement for the small diameter roll is also utilized to drive the corrugating roll pair.  
         BACKGROUND OF THE INVENTION  
         [0002]    In the manufacture of corrugated paperboard, a single facer apparatus is used to corrugate the medium web, to apply glue to the flute tips on one face of the corrugated medium web, and to bring a liner web into contact with the glued flute tips of the medium web with the application of sufficient heat and pressure to provide an initial bond. For many years, conventional single facers have typically included a pair of fluted corrugating rolls and a pressure roll, which are aligned so that the axes of all three rolls are generally coplanar. The medium web is fed into a corrugating nip formed by the interengaging corrugating rolls. While the corrugated medium web is still on one of the corrugating rolls, adhesive is applied to the flute tips by a glue roll. The liner web is immediately thereafter brought into contact with the adhesive-coated flute tips and the composite web then passes through the nip formed by the corrugating roll and the pressure roll.  
           [0003]    In the past, the fluted corrugating rolls have typically been generally the same size. More recently, a significantly improved single facer apparatus has been developed in which the corrugating rolls comprise a large diameter bonding roll and a substantially smaller diameter roll, with the ratio of diameters being 3:1 or greater. Such apparatus is disclosed in U.S. Pat. Nos. 5,628,865, 5,951,816, and 6,012,501, all which disclosures are incorporated herein by reference. In accordance with these disclosures, the single facer typically includes a backing arrangement for the small diameter corrugating roll. One preferred backing arrangement includes a series of axially adjacent pairs of backing idler rollers, each pair having a backing pressure belt entrained therearound. Each of the pressure belts is positioned to bear directly against the fluted surface of the small diameter corrugating roll on the side of the small corrugating roll opposite the corrugating nip. Each pair of associated idler rolls and pressure belts is mounted on an actuator, and can thus engage the small diameter corrugating roll with a selectively adjustable force. The application of force against the small diameter corrugating roll, in turn, applies force along the corrugating nip between the small diameter roll and the large diameter roll and along the full length of the nip. Typically, a force of approximately 100 lbs. per linear inch (e.g. 10,000 lbs. for a 100 inch roll) is desirable for properly fluting a medium web at typical line speeds.  
           [0004]    In my co-pending application, filed on ______ and entitled “Single Facer with Quick Change Rolls”, a single facer apparatus is disclosed in which three matching pairs of large diameter and small diameter corrugating rolls may be easily interchanged. In that apparatus, the interchangeable large diameter corrugating rolls are carried on a rotatable turret and the small diameter corrugating rolls are supplied from a storage magazine positioned laterally offset from the turret and the single facer machine. Because the large diameter corrugating rolls also function as heated bonding rolls, they are supplied with steam and must also be provided with a facility to collect and return the condensate. The large diameter bonding roll is typically directly driven and, in my improved apparatus with three large diameter bonding rolls mounted on a turret, driving the single facer with a direct drive to the large diameter bonding roll provides a complicated and challenging engineering problem. Likewise, an attempt to provide a direct drive to the small diameter corrugating roll, which has to be replaced to match the repositioning of a new large diameter bonding roll, would also be complex and difficult.  
           [0005]    Thus, some other means of driving the single facer corrugating rolls would be most desirable.  
         SUMMARY OF THE INVENTION  
         [0006]    In accordance with the present invention, the pressure belt arrangement for supporting the small diameter corrugating roll also provides rotatable drive to the small diameter roll from which driving rotation is transmitted through the nip to the large diameter corrugating roll.  
           [0007]    In a single facer apparatus in which a single face corrugated web is formed, which apparatus includes a large diameter fluted corrugating roll, a small diameter fluted corrugating roll that is positioned to interengage the large diameter roll to create a corrugating nip, a plurality of backing roll arrangements positioned in operative rotatable engagement with the small diameter corrugating roll, each of which backing roll arrangements includes pairs of backing rolls mounted on a support assembly and a pressure belt entrained around each pair of backing rolls, and an actuator arrangement that is operatively connected to the support assemblies to impose a variable backing force on the backing roll arrangements to force the pressure belts into contact with the small diameter corrugating roll; the improvement provided by this invention comprises a drive arrangement that includes a common drive connection to one of the rolls of each backing roll pair; a source of motive power operatively connected to the drive connection to rotatably drive the commonly connected backing rolls; and, said actuator arrangement being operative to transmit a backing force to the pressure belts and the small diameter corrugating roll sufficient to transmit driving rotation from the small diameter roll through the nip to the large diameter corrugating roll.  
           [0008]    Preferably, the commonly connected backing rolls are arranged coaxially along a common axis of rotation and the drive arrangement comprises a drive shaft disposed on the common axis and connected to the source of motive power. In this embodiment, the commonly connected backing rolls comprise toothed sheaves fixed to the drive shaft, and the pressure belts are provided with toothed inner faces for driving engagement with the backing rolls. In the preferred embodiment, each of the commonly connected backing rolls supports a plurality of axially adjacent pressure belts. The actuator arrangement preferably comprises an actuator for each of the backing rolls that forms the other of said backing roll pairs.  
           [0009]    The method of driving a single facer, in accordance with the present invention, includes the steps of (1) providing one of the rolls of each backing roll pair with a common rotatable drive connection, (2) driving the drive connection to rotatably drive the commonly connected backing rolls and the pressure belts entrained thereon, (3) supporting the backing rolls and pressure belts to apply a selectively variable radial backing force to the small diameter corrugating roll, and (4) applying a radial force sufficient to transmit driving rotation a small diameter corrugating roll and through the nip to the large diameter corrugating roll.  
           [0010]    The method preferably includes the steps of mounting the commonly connected backing rolls coaxially on a common axis of rotation, and rotatably interconnecting said commonly connected backing rolls with a drive shaft disposed on the common axis. The method further includes the step of providing the commonly connected backing rolls and the pressure belts with a toothed interface for positive driving engagement. The method further comprises the step of supporting a plurality of axially adjacent pressure rolls on each of said commonly connected backing rolls. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a side elevation view of a current state-of-the-art single facer incorporating a corrugating roll drive arrangement of the present invention.  
         [0012]    [0012]FIG. 2 is a side elevation view of an improved single facer including the drive arrangement of the present invention.  
         [0013]    [0013]FIG. 3 is an isometric view of the apparatus shown in FIG. 2.  
         [0014]    [0014]FIG. 4 is a rear elevation view of the single facer shown in FIG. 2.  
         [0015]    [0015]FIG. 5 is an enlarged detail of a portion of the apparatus shown in FIG. 4. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    Referring initially to FIG. 1, a single facer  10  includes a large diameter upper corrugating roll  11  (sometimes hereinafter referred to as bonding roll  11 ) and a much smaller diameter lower corrugating roll  12 . Both rolls  11  and  12  may be made of steel or other suitable materials and are fluted and mounted for interengaging rotational movement on parallel axes, all in a manner well known in the art, as described in detail in the above identified patents and patent applications. A medium web  13 , which is typically pretreated by moistening and heating, is fed into a corrugating nip  14  formed by the interengaging corrugating rolls  11  and  12 . As the corrugated medium web  13  leaves the nip  14 , it remains on the surface of the large diameter bonding roll  11 . Immediately downstream from the nip  14  a glue roll  15  applies a liquid adhesive, typically starch, to the exposed flute tips of the corrugated medium web  13 . Immediately thereafter, a liner web  16  is brought into contact with the glued flute tips of the corrugated medium web by a liner delivery roll  17 , sometimes referred to as a generator roll. The resulting freshly glued single face web  18  continues around a portion of the outer circumference of the large diameter bonding roll  11 . The initial bond between the medium web  13  and liner web  16  may be assisted with a soft contact roll  19  located immediately downstream from the delivery roll  17 . The soft contact roll  19  presses the composite single face web  18  against the bonding roll  11  with a light and uniform force distributed across the full width of the web. Because the large diameter roll  11 . also functions as a bonding roll, it is internally heated, for example with steam, to cause the starch adhesive to initially gelatinize and then enter the so-called “green bond” stage. By assuring that green bond is reached while the single face web  18  is still on the bonding roll  11 , integrity of the glue lines is better assured and downstream handling, including back wrapping around a wrap roll  21 , is not likely to disturb the bond. The extent of the wrap of the single face web  18  on the bonding roll and thus the circumferential residence time of the single face on the bonding roll may be varied by adjustably positioning the wrap roll along a positioning mechanism  20 . The vertical position of the wrap roll  21  with respect to the surface of the bonding roll  11  may be selectively adjusted depending on a number of variables, such as paper weight, web speed, bonding roll temperature, starch composition, and the like. Alternately, the position of the wrap roll may be fixed particularly in the preferred embodiment described below with respect to FIGS.  2 - 5 .  
         [0017]    In the single facer shown in FIG. 1, the large diameter corrugating and bonding roll  11  typically has a diameter of about 39 inches (about 1,000 mm) and the smaller diameter lower corrugating roll  12  typically has a diameter of about 5 inches (about 130 mm). The prior art identified above and incorporated herein provides various backing arrangements for the small diameter roll  12 , one of which backing arrangements  23  is shown in the drawing. The backing arrangement  23  includes a series of axially adjacent pairs of backing rolls  24 , each of which pairs has a pressure belt  25  entrained therearound. Each of the pressure belts  25  is positioned to bear directly against the fluted outer surface of the small diameter corrugating roll  12 . Each pair of idler rolls  24  and its respective pressure belt  25  is mounted on an actuator  26 . By individually controlled operation of each actuator  26 , the pressure belts may be made to engage the small diameter corrugating roll  12  with a selectively adjustable force. In current state-of-the-art single facers, the large diameter bonding roll  11  is typically driven by the main drive motor. In accordance with the present invention, however, all of the axially aligned backing rolls  24  on one side of the lower corrugating roll  12  are converted from idler rolls to drive rolls  28 . The drive rolls  28  are mounted on a common drive shaft  30 , the lateral outer end of which is operatively connected to a main drive motor  27 . The drive rolls  28  are provided with a toothed outer surface to cooperate with a correspondingly toothed pressure belt  25  which may be conveniently in the form of a conventional reinforced rubber timing belt  31 . By driving the drive rolls  28  together and applying an appropriate backing force to the backing arrangement  23  with the actuators  26 , the lower corrugating roll  12  may be suitably driven due to approximately 90° of wrap of pressure belts  25  around the roll  12 . The driving force is transmitted through the nip  14  to the bonding roll  11 .  
         [0018]    Referring now to FIGS.  2 - 5 , there is shown an improved single facer  32  incorporating the unique indirect corrugating roll drive of the present invention in a machine construction in which multiple corrugating roll pairs may be changed to provide different flute patterns. The corrugating roll pair interchange system is described in detail in my co-pending application identified above.  
         [0019]    The single facer  32  includes a large diameter bonding roll  33  in operative position and mounted on a rotatable turret  34  with two similar bonding rolls  33 . Rotation of the turret  34  on its axis  35  brings a selected one of the bonding rolls  33  into operative position to form a nip  37  with a small diameter corrugating roll  36 . The large diameter bonding roll  33  may have a diameter of 22.5 in. (about 570 mm) and the small diameter corrugating roll  36  having a diameter of 7.5 in. (about 190 mm). Each of the large diameter bonding rolls  33  may be provided with a different flute pattern and, for the particular bonding roll chosen and rotated into operative position, the interengaging small diameter corrugating roll  36  must also be changed to one having a corresponding flute pattern.  
         [0020]    In a manner similar to the single facer  10  shown in FIG. 1, a medium web  38  is fed into the corrugating nip  37  and, after corrugating, remains on the surface of the bonding roll  33 . A starch adhesive is applied to the exposed flute tips of the corrugated medium web  38  on the bonding roll by a glue roll  40  and, immediately thereafter, a liner web  41  is brought into contact with the glued tips of the corrugated medium web delivered by a generator roll  42  to form a single face web  43 . By retaining the freshly glued single face web  43  on the heated bonding roll  33  over a substantial extent of its circumference, an adequate green bond is formed in the glue lines such that, when the single face web  43  is taken off the bonding roll as by wrapping around an exit roll  44 , the green bond strength is adequate to assure that the bond between the medium web  38  and liner web  41  is not disturbed.  
         [0021]    The small diameter corrugating roll  36  is supported to maintain an adequate nipping force and to prevent axial bending of the roll with a backing arrangement  45  that is similar to the backing arrangement  23  of the FIG. 1 embodiment. Thus, pairs of backing rolls  46  are positioned on opposite sides of the small diameter corrugating roll  36  and pressure belts  47  are entrained around the rolls and support the small diameter roll from beneath. However, one axially aligned row of backing rolls is mounted on a drive shaft  48  that extends across and beyond the full width of the machine in the cross machine direction. The rolls are keyed or otherwise fixed to the drive shaft  48  and act as drive rolls  50 . Referring also to FIGS. 4 and 5, each drive roll  50  is provided with a toothed outer surface so that it may positively engage and drive pressure belts  47  also having a toothed construction in the manner of a timing belt. Each drive roll  50  is of extended axial length so that it can accommodate more than one pressure belt  47 . In the embodiment shown, the drive roll  50  has an axial length adequate to carry five adjacent pressure belts. Between each drive roll  50  and at the outer ends of the two outermost drive rolls, the drive shaft  48  is supported in bearings  51  conveniently mounted in split hanger brackets  52  to facilitate removal of the drive shaft and drive rolls to change the pressure belts  47 .  
         [0022]    The opposite row of backing rolls  46  may be comprised of the same idler rolls  24  described with respect to the FIG. 1 embodiment, each carrying a single pressure belt  47 . In other words, each drive roll  50 , carrying five pressure belts  47 , will be interconnected thereby with five backing rolls  46 .  
         [0023]    The backing arrangement  45  of this embodiment also differs from the FIG. 1 embodiment in the manner in which the backing force on the small diameter corrugating roll  36  is applied. Because it is necessary or at least highly desirable not to move the axis of the drive shaft  48  and drive rolls  50 , the backing arrangement  45  is arranged to mount each backing roll  46  on its own pivot arm  49  and to place the loading actuators  53  below each of the backing rolls  46  and in operative engagement with the pivot arms. The actuators  53  may comprise pneumatic cylinders, air bags, or any other suitable device. In operation, the actuators  53  are extended to pivot the arms  49  and backing rolls  46  upwardly around the common axis of the opposite ends of the arms  49 , causing the pressure belts  47  to load the small diameter corrugating roll  36  against the bonding roll  33  at the nip  37 . The main drive motor  54  is operatively connected to one outer end of the drive shaft  48  (see FIG. 2), whereby the drive rolls  50  impart driving rotation to the backing rolls  46  and pressure belts  47 . Pressure belt movement imparts rotation to the small corrugating roll  36  which is transmitted through the nip to the bonding roll  33  causing it to rotate with the small corrugating roll.