Abstract:
A corrugator single facer of the type utilizing a large diameter bonding roll and a small diameter corrugating roll provides quick roll change capability by mounting three large diameter bonding rolls on a rotatable turret and carrying corresponding small diameter corrugating rolls in a magazine positioned laterally offset from the machine. By driving the corrugating rolls indirectly through the pressure belt arrangement which supports the lower corrugating roll, roll change is significantly simplified.

Description:
FIELD OF THE INVENTION 
     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 alternate pairs of large and small corrugating rolls with different flute patterns may be rapidly changed. 
     BACKGROUND OF THE INVENTION 
     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. 
     In the past, the fluted corrugating rolls have typically been generally the same size as each other. 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 a linear 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. 
     In my co-pending application, filed on Oct. 9, 2001 and entitled “Single Facer Drive Apparatus”, a single facer apparatus is disclosed in which 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. 
     There have been many attempts in the prior art to construct a single facer with interchangeable corrugating roll pairs so that a flute change can be made quickly and easily. Various types of apparatus have been designed for this purpose, including pairs of upper and lower corrugating rolls each mounted a rotatable spindle to change from one roll pair to another. Other constructions have provided means for simply lifting the rolls from operating position and replacing them with another pair. 
     With the introduction of the current state-of-the-art single facer using a large diameter bonding roll, roll replacement has become more difficult, even though the ability to rapidly change corrugating roll pairs remains just as important. It would, therefore, be most desirable and advantageous to provide for a quick corrugating roll pair change in a modern single facer of the type utilizing a large diameter bonding roll in cooperation with a much smaller corrugating roll. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, three matching pairs of large diameter and small diameter corrugating rolls may be easily interchanged. 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. 
     More specifically, a single facer apparatus for producing a single face web from a corrugated medium web and a liner comprising a rotatable turret carrying at least two, but preferably three, independently rotatable large diameter fluted bonding rolls on parallel rotational axes, a positioning device that is operable to rotate the turret to place a bonding roll into an operative position, a magazine carrying at least two, but preferably three, small diameter fluted corrugating rolls in a storage position offset laterally from the turret and the bonding rolls, a transfer device that is operable to move a corrugating roll axially from the magazine into an operating position adjacent the bonding roll in the operative position, and a corrugating roll support device to rotatably support the corrugating roll in operative engagement with the bonding roll. In the preferred embodiment, the transfer design is operable to move a corrugating roll axially to and from the operating position in the single facer and the storage position in the magazine. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of a current state-of-the-art single facer incorporating a corrugating roll drive arrangement of a type especially suitable in a single facer of the present invention. 
     FIG. 2 is a side elevation view of the single facer of the present invention. 
     FIG. 3 is an isometric view of the apparatus shown in FIG.  2 . 
     FIG. 4 is a rear elevation view of the single facer shown in FIG.  2  and showing details of the corrugating roll drove arrangement. 
     FIG. 5 is an enlarged detail of a portion of the apparatus shown in FIG.  4 . 
     FIGS. 6-8 are isometric views of the single facer of the present invention showing details of the construction and sequential function of the device for changing the lower small diameter corrugating roll. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     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 construction of the preferred embodiment described below with respect to FIGS. 2-8. 
     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 invention described in my co-pending application identified above, 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° or more of wrap of the pressure belts  25  around the roll  12 . The driving force is transmitted through the nip  14  to the bonding roll  11 . 
     Referring now to FIGS. 2-5, there is shown an improved single facer  32  of the present invention in which multiple corrugating roll pairs may be changed to provide different flute patterns. The corrugating roll pair interchange system of this invention is preferably used with the indirect corrugating roll drive described in detail in my co-pending application filed concurrently herewith. 
     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 . 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. 
     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. 
     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 . 
     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 . 
     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. 
     As shown in its operative position in FIG. 3, the small diameter corrugating roll  36  is supported by the pressure belt arrangement  45  and is also supported for rotation on its axis on the stub shaft  55  of a spindle  56 . The spindle is mounted for angular pivotal movement on the drive shaft  48  and is also movable axially with respect to the small corrugating roll  36  so that the stub shaft  55  can be withdrawn from rotational support thereof. When it is desired to change the corrugating roll pair  33  and  36 , and referring also to FIG. 6, the glue roll  40  and its associated metering roll  39  are mounted on a separate carriage  57  which is moved laterally away from the corrugating rolls. The generator roll  42  is also swung away from the single facer (as best seen in FIG.  1 ). On the other side of the machine, the exit roll  44  is also dropped down and away from the bonding roll  33 . All of the foregoing movements are to provide clearance for the movement of the bonding rolls and the turret  34  on which they are mounted. It should be noted that each bonding roll  33  on the turret carries with it a separate vacuum plenum  58 . The use of a vacuum plenum is well known in the art and it is positioned, as shown in FIGS. 2 and 3, in an operative position to apply a vacuum through a series of grooves and passages to the surface of the bonding roll to assist in maintaining the single face web in contact therewith. 
     To complete the preparation of the machine for corrugating roll exchange, the actuators  53  in operative contact with the backing idler rolls  46  are retracted to drop the rolls and the pressure belts. The stub shaft  55  is withdrawn axially from the end of the small corrugating roll  36  and the spindle  56  pivoted upwardly and out of the way. The small diameter corrugating roll  36  is then clear for withdrawal from the machine in the lateral or cross machine direction along its axis. The small diameter corrugating roll  36  is shown partially withdrawn in FIG. 7 where the leading end of the roll is supported on a series of aligned support rolls  60  of a magazine  61 . The magazine includes sets of parallel support rolls  60  which support similar corrugating rolls (not shown) each having a flute pattern matching that of one of the bonding rolls  33 . When the small diameter roll  36  is fully withdrawn from the machine, the turret  34  is rotated to bring a new bonding roll  33  into position and the magazine  61  is indexed sideways to bring the small diameter corrugating roll  36  matching the new bonding roll  33  into loading position. The process just described for removing the small corrugating roll is reversed and the new roll brought into operative position above the pressure belts  47  and below the bonding roll  33 . 
     One type of apparatus for extracting the small diameter corrugating roll  36  from the machine, placing it in the magazine  61 , and moving the new small roll into position in the machine is an extractor mechanism that engages a lip  62  on the end of the roll  36 . By engaging the lip, the extractor mechanism can be used to pull the roll from its operative position in the single facer onto the magazine  61 , and to push the replacement small diameter corrugating roll  36  from the magazine into position between the pressure belts  47  and the newly selected bonding roll  33 . Alternately, a roll-supporting slide device could be utilized instead of the support rolls  60 . To assist the axial movement of the small diameter corrugating roll  36  from its operative position to the storage magazine  61 , a series of laterally spaced guides may be placed along the length of the small corrugating roll and between the pressure belts  47 . When the backing arrangement including the pressure belts is lowered for roll change, the spaced guides will extend above the pressure belts and support the small roll as it is pulled from its operative position by the extractor mechanism. 
     In the single facer  32  of the present invention, the ratio of diameters of the large diameter bonding roll  33  to the small diameter corrugating roll  36  is preferably smaller than in the present state-of-the-art machine  10  shown in FIG.  1 . In the preferred embodiment of the present invention, the large diameter bonding roll may have a diameter of about 22.5 inches (570 mm) and the small diameter roll a diameter of about 7.5 inches (190 mm), a ratio of 3:1. By utilizing the indirect corrugating roll drive described herein, direct mechanical driving connection to the large bonding roll  33  (or the small corrugating roll  36 ) is eliminated, leaving only steam supply and condensate removal to be provided to the turret  34 . In most cases, it will be necessary to have a separate vacuum plenum  58  to be carried with each of the bonding rolls  33  because variations in flute patterns from one roll to another also typically result in changes in vacuum groove patterns as well. As indicated above, because the diameter of the large bonding roll  33  in the preferred embodiment of FIG. 2 is substantially smaller than the diameter of the bonding roll  11  in the current state-of-the-art single facer shown in FIG. 1, it is preferable to fix the operating position of the exit roll  44  in the preferred embodiment at a point that maximizes the wrap of the single face web  43  on the bonding roll. Elimination of the exit roll positioning mechanism ( 20  in FIG. 1) also simplifies the construction of the single facer. As may be seen in FIG. 2, the improved single facer of the present invention still provides the capability for more than 180° of circumferential wrap of the single face web on the bonding roll  33 . 
     It may also be desirable to utilize an alternate means for driving the corrugating rolls  33  and  36  from the drive disclosed herein which is the subject of my co-pending application entitled “Single Facer Drive Apparatus”. In such an alternate drive arrangement, the main drive motor  54  is provided with a driving connection directly to the small diameter corrugating roll  36 . Preferably, the drive connection is made at the axial opposite end of the roll from that shown in the drawings (in other words, at the roll end opposite the spindle  56  and roll supporting hub  55 ). The drive connection to the small diameter corrugating roll  36  could be a drive cone, a splined stub shaft or any similar arrangement which would allow the roll to be withdrawn axially for roll change and a new roll to be easily connected to the drive.