Abstract:
A machine for manufacturing corrugated board that includes a row of pressure applicators aligned substantially transverse to the direction of machine flow and configured to press a web of corrugated board against a heated platform. To prevent the pressure applicators from tilting when incompletely overlying the web of corrugated board, the machine includes a stabilizer configured to prevent one or more of the pressure applicators from tilting. The stabilizer may include support plates connected to the pressure applicators and a stabilizer strap connecting two of the support plates to prevent the pressure applicator from tilting. Alternatively, the stabilizer may include support plates connected to the pressure applicators and one or more alignment members to prevent the pressure applicator from tilting. The alignment members may be alignment blocks or rollers.

Description:
REFERENCED TO RELATED APPLICATIONS  
       [0001]    This application incorporates by reference the disclosure of commonly-owned U.S. Pat. No. 6,390,963 entitled “Corrugated Board Manufacturing Apparatus Including a Preheater Section with a Variable Heat Transfer System and a Hotplate Section with a Passive Hold-Down Mechanism” issued on May 21, 2002. 
     
    
     
       TECHNICAL FIELD  
         [0002]    This invention relates to machines for manufacturing cardboard boxes and, more specifically, relates to a machine with stabilizers that prevent the pressure applicators from tilting when they partially overlie a web of corrugated board.  
         BACKGROUND OF THE INVENTION  
         [0003]    Machines for manufacturing corrugated board may include a segmented hold-down structure consisting of a grid of pressure applicators including a number of rows, each including a number of individual pressure applicators. These pressure applicators press a moving web of corrugated board against a heated platform, such as a steam chest, to dry the board and set the glue as the web of corrugated board is propelled through the machine. In a belt driven machine, the pressure applicators directly press against a conveyor belt, which in turn presses the board against the steam chest, as the conveyor belt propels the board through the machine. In a beltless machine, the pressure applicators press directly against the corrugated board, which is typically pulled through the steam chest section of the machine by a vacuum or belt drive located downstream from the steam chest.  
           [0004]    For either type of machine, segmenting the pressure applicator structure into a grid of pressure applicators allows the number of rows engaging the board in the direction of machine flow to be varied in response to the speed of the machine and the thickness of the corrugated board. In addition, segmenting each row of pressure applicators into a number of separate pressure applicators in the cross-machine direction allows the number of pressure applicators engaging the board to be varied in response to the width of the corrugated board. In addition, the pressure applied by the pressure applicators in the cross-machine direction may be varied to apply a desired pressure profile to the board.  
           [0005]    An inexpensive yet effective pressure applicator structure including passive pressure applicators is described in commonly-owned U.S. Pat. No. 6,390,963 entitled “Corrugated Board Manufacturing Apparatus Including a Preheater Section with a Variable Heat Transfer System and a Hotplate Section with a Passive Hold-Down Mechanism.” In this machine, the downward pressure applied by the pressure applicators are not actively controlled. Instead, the pressure applicators are individually weighted to impart a desired pressure profile on the underlying board. The use of passive pressure applicators eliminates much of the machine&#39;s control system, which results in an inexpensive machine that is east to set up and operate.  
           [0006]    In this type of machine, one or more pressure applicators at each end of each row typically include actuators, such as air cylinders, to independently lift a corresponding pressure applicator off the underlying board. This feature allows the machine to accommodate less than full-width board. Typically, each row includes eight hold-down pressure applicators with the outermost two pressure applicators at the end of each row including independent lifting actuators. This allows the center four, the center six, or all eight hold-down feed to engage the corrugated board of varying width.  
           [0007]    With this type of machine, however, the pressure applicators pressing down against the edges of the corrugated board do not always overlie the board completely. In particular, when less than half of a pressure applicator overlies the edge of the board, the pressure applicator can tilt. When this happens, the edge of the board can be pinched, and a portion of the board may not receive adequate downward pressure. This causes the board to be manufactured improperly, which results in waste board. In addition, the pressure applicator may press the conveyor belt against the steam chest, which can quickly destroy the conveyor belt.  
           [0008]    Therefore, a need exists for a segmented pressure applicator system that prevents individual pressure applicators from tilting when incompletely overlying a web of corrugated board.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention meets the needs described above in a machine for manufacturing corrugated board that includes a heated platform and a conveyor for propelling a web of corrugated board adjacent to the heated platform in a machine direction. The machine also includes a row of pressure applicators aligned substantially transverse to the direction of machine flow and configured to press the web of corrugated board against the heated platform. To prevent the pressure applicators from tilting when incompletely overlying a web of corrugated board, the machine includes a stabilizer configured to prevent a corresponding pressure applicator from tilting while applying pressure to the web of corrugated board.  
           [0010]    Each pressure applicator may be independently weighted, and the weights of the pressure applicators may be selected to impart a desired pressure profile to the web. The machine may also include a lifting apparatus for lifting a corresponding pressure applicator independently of the other pressure applicators. In particular, the stabilizer may include a connector, such as a flexible strap or rigid bar, securing two pressure applicators to each other. For example, the connector may secure a right end pressure applicator to a left end pressure applicator. And a second connector may secure a right second position pressure applicators to a left second position pressure applicator. In this case, the right second position pressure applicator is typically located adjacent to the right end pressure applicator, and the left second position pressure applicators is typically located adjacent to the left end pressure applicator.  
           [0011]    To remove pressure from the web, a support bar configured to lift a row of pressure applicators may be moved from a lower position to an upper position. The support bar is configured to lift the pressure applicators above the corrugated board when moved to the upper position, and to permit the pressure applicators to move vertically with respect to the support bar when moved to the lowered position to remove the weight of the pressure applicator from the support bar and to apply the weight of the pressure applicators to the corrugated board. To implement the stabilizer, a support structure is coupled to a pressure applicator, and one or more alignment members are supported by the support bar and configured to limit lateral movement of the support structure to permit the support structure to move vertically with respect to the support bar while preventing the pressure applicator from tilting.  
           [0012]    For example, the support structure may include a support surface and one or more alignment members supported by the support bar and positioned adjacent to the support surface to limit lateral movement of the support structure while permitting the support structure to move vertically with respect to the support bar. Each support structure may include one or more support surfaces and one or more alignment members positioned adjacent to the support surfaces. For example, the support surface may be defined by the edge of a support plate, and the alignment members may include one or more alignment blocks or rollers.  
           [0013]    More specifically described, a first embodiment of invention includes a machine for manufacturing corrugated board including a heated platform and a conveyor for propelling a web of corrugated board adjacent to the heated platform in a machine direction. The machine also includes a row of pressure applicators aligned substantially transverse to the direction of machine flow and configured to press the web of corrugated board against the heated platform. To prevent the pressure applicators from tilting when incompletely overlying a web of corrugated board, the machine includes a first stabilizer including a connector securing opposing end position pressure applicators to each other to prevent the end position pressure applicators from tilting while applying pressure to the web of corrugated board. The machine may also include a second stabilizer including a connector securing opposing second position pressure applicators to each other to prevent the second position pressure applicators from tilting while applying pressure to the web of corrugated board. Typically, each second position pressure applicator is located adjacent to a corresponding end position pressure applicator. The connector may include a flexible strap or rigid bar connecting support structures to each other. Each support structure, such as an “L” bracket, is typically attached to an associated pressure applicator.  
           [0014]    A second embodiment of the invention includes a machine for manufacturing corrugated board including a heated platform, a conveyor for propelling a web of corrugated board adjacent to the heated platform in a machine direction, and a row of pressure applicators aligned substantially transverse to the direction of machine flow and configured to press the web of corrugated board against the heated platform. The machine also includes a support bar selectively supporting the row of pressure applicators that may be moved from an upper position to a lower position. The support bar is configured to lift the pressure applicators above the corrugated board when moved to the upper position, and to permit the pressure applicators to move vertically with respect to the support bar when moved to the lowered position to remove the weight of the pressure applicator from the support bar and to apply the weight of the pressure applicators to the corrugated board. The machine also includes a first support structure coupled to a pressure applicator, such as a right end pressure applicator, and one or more alignment members supported by the support bar and positioned to the first support structure to permit the first support structure to move vertically with respect to the support bar while preventing the right end position pressure applicator from tilting.  
           [0015]    The machine may also include a second support structure coupled to a left end pressure applicator, and one or more alignment members supported by the support bar and positioned adjacent to the second support structure to permit the second support structure to move vertically with respect to the support bar while preventing the left end pressure applicator from tilting. The machine may also include a third support structure coupled to a right second pressure applicator, and one or more alignment members supported by the support bar and positioned adjacent to the third support structure to permit the third support structure to move vertically with respect to the support bar while preventing the right second position pressure applicator from tilting. The machine may also include a fourth support structure coupled to a left second position pressure applicator, and one or more alignment members supported by the support bar and positioned adjacent to the fourth support structure to permit the fourth support structure to move vertically with respect to the support bar while preventing the left second position pressure applicator from tilting.  
           [0016]    In various alternatives, each support structure may include a support surface and an alignment block positioned adjacent to the support surface, a support surface and one or more rollers adjacent to the support surface, two support surfaces and one roller adjacent to each support surface, two support surfaces and two rollers adjacent- to each support surface, or two support surfaces, two rollers adjacent to one of the surfaces, and one roller adjacent to the other support surface. In addition, each support structure may comprise a support plate attached to the pressure applicator.  
           [0017]    The specific techniques and structures employed by the invention to improve over the drawbacks of prior pressure applicator structures and accomplish the advantages described above will become apparent from the following detailed description of the embodiments of the invention and the appended drawings and claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIGS. 1A, 1B and  1 C are plan views of a prior art pressure applicator structure for a machine for manufacturing corrugated board.  
         [0019]    [0019]FIGS. 2A and 2B are plan views of a prior art pressure applicator structure for a machine for manufacturing corrugated board illustrating tilted pressure applicators that can occur with this type of machine.  
         [0020]    [0020]FIG. 3 is a plan view of a pressure applicator structure for a machine for manufacturing corrugated board including a first type of stabilizer for preventing the pressure applicators from tilting.  
         [0021]    [0021]FIG. 4 is a plan view of a pressure applicator structure for a machine for manufacturing corrugated board including a second type of stabilizer for preventing the pressure applicators from tilting.  
         [0022]    [0022]FIG. 5 is a perspective view of pair of pressure applicators in which one pressure applicator includes a support plate and two alignment blocks to prevent the pressure applicator from tilting.  
         [0023]    [0023]FIG. 6 is a perspective view of a row pressure applicators including two stabilizers to prevent two pressure applicators at either end of the row from tilting.  
         [0024]    [0024]FIG. 7 is a side view of a pressure applicator including a stabilizer to prevent the pressure applicator from tilting.  
         [0025]    [0025]FIG. 8 is a front view of a pressure applicator including a stabilizer with two rollers to prevent the pressure applicator from tilting.  
         [0026]    [0026]FIG. 9 is a front view of a pressure applicator including a stabilizer with three rollers to prevent the pressure applicator from tilting.  
         [0027]    [0027]FIG. 10 is a front view of a pressure applicator including a stabilizer with four rollers to prevent the pressure applicator from tilting. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0028]    The present invention may be embodied in a machine for manufacturing corrugated board with a segmented pressure applicator structure with one or more stabilizers configured to prevent one or more pressure applicators from tilting while applying pressure to the web of corrugated board. Several types of stabilizers may be deployed. For example, a first type of stabilizer ties two pressure applicators together to prevent them from tilting. Another type of stabilizer includes a support structure, such as a support plate, coupled to a pressure applicator. This type of stabilizer also includes an alignment mechanism positioned adjacent to the support structure to prevent the pressure applicator from tilting. For example, the support structure may include a support plate attached to a pressure applicator with one or more edges defining support surfaces. The alignment mechanism may include one or more alignment blocks or rollers located adjacent to each support surface.  
         [0029]    It should be appreciated that any of these stabilizers may be deployed on a machine for manufacturing corrugated board, or they may be deployed in combination. The stabilizers may be deployed on a new machine, or they may be deployed as a retrofit to an existing machine. In addition, stabilizers are typically only deployed for the end pressure applicators of a cross-machine row, or two end pressure applicators on each end of a cross-machine row. This is because corrugated board requiring a narrower pressure applicator structure is seldom encountered. However, additional stabilizers could be added if desired. In addition, the embodiments of the invention described below include certain structures, such as support plates, straps, bars, block and rollers. However, it should be appreciated that these components may be replaced by equivalent structures configured to accomplish a similar purpose.  
         [0030]    Turning now to the drawings, in which like element numerals indicate like elements throughout the several figures, FIGS. 1A, 1B and  1 C are plan views of a prior art machine for manufacturing corrugated board  10  including a heated platform  12 , such as a steam chest, and a row of pressure applicators  13 . The machine  10  is described in more detail in commonly-owned U.S. Pat. No. 6,390,963 entitled “Corrugated Board Manufacturing Apparatus Including a Preheater Section with a Variable Heat Transfer System and a Hotplate Section with a Passive Hold-Down Mechanism” issued on May 21, 2002, which is incorporated into this specification by reference.  
         [0031]    Although FIGS.  1 A-C illustrate only one row of the pressure applicator structure  13 , the machine  10  may include a number of similar rows, such as twenty. Each pressure applicator serves to press a web of corrugated board  14  against the steam chest  12  to dry the board and set the glue as the corrugated board is propelled through the machine. In the belt driven machine illustrated in FIGS.  1 A-C, the pressure applicators  13  directly press against a conveyor belt  16 , which in turn presses the board  14  against the steam chest  12 , as the conveyor belt  16  propels the board  14  through the machine  10 . The pressure applicator stabilizers described below may also be deployed with a beltless machine, in which the pressure applicators  13  press directly against the corrugated board  14 . In this type of machine, the web of corrugated board  14  is typically pulled through the steam chest section of the machine by a vacuum or belt drive located downstream from the steam chest  12 .  
         [0032]    The machine  10  includes a support bar  18  that supports the row of pressure applicators  13 . The machine also includes one or more actuators  20 , such as an air cylinder, for raising and lowering the support bar  18 . When the support bar  18  is in the upper position, as shown in FIG. 1A, the pressure applicators  13  are lifted above the board  14  and do not press the board against the steam chest  12 . In particular, the support bar  14  lifts each pressure applicator by lifting a pair of support piers  21  that rest on the topside of the support bar  18 . However, support piers  21  are not otherwise constrained by the support bar  18 , which allows the pressure applicator to move vertically with respect to the support bar  18  when the pressure applicators are lowered into contact with the underlying conveyor belt  16  and board  14 . This shifts the weight of the pressure applicators  13  from the support bar  18  to the conveyor belt  16  and board  14  when the support bar  18  is in the lower position, as shown in FIG. 1B. The pressure applicators  13  may be individually weighted to apply a desired pressure profile to the board  14 , and the downward pressure applied by the pressure applicators  13  may not be otherwise controlled. The use of this type of passive hold-down structure eliminates much of the machine&#39;s control system, which results in an inexpensive machine that is east to set up and operate.  
         [0033]    To accommodate board  14  that is less than the full width of the row of pressure applicators  13 , the left and right end pressure applicators  22  and  24  of the row may be independently lifted by actuators  26  and  28 , respectively, as shown in FIG. 1C. Although air cylinders operate well as the actuators  22  and  24 , they may be implemented using hydraulic cylinders, air bags, ball screws, scissors lifts, or any other suitable lifting device. Although only the left and right end pressure applicators  22  and  24  are shown with actuators  26  and  28 , respectively, each row of pressure applicators may include eight hold-down pressure applicators with the outermost two pressure applicators at the end of each row including independent lifting actuators. That is, the left second position pressure applicator  36  and the right second position pressure applicator  38  may also include actuators. This configuration allows the center four, the center six or all eight hold-down feed to engage the corrugated board to accommodate corrugated board of varying width. Of course, a different number of pressure applicators may be included in each row, and a different number of pressure applicators of each row may include stabilizers, as desired.  
         [0034]    [0034]FIGS. 2A and 2B are plan views of the prior art machine  10  illustrating tilted pressure applicators that can occur with this type of system. Specifically, when the corrugated board  14  underlie less than half of a pressure applicator, as shown in FIG. 2A for the left and right end pressure applicators  22  and  24 , these pressure applicators can tilt as shown in shown in FIG. 2B. When this happens, the edge of the board  14  can be pinched, and a portion of the board may not receive adequate downward pressure. This causes the board to be manufactured improperly, which results in waste board. In addition, the tilted pressure applicator may press the conveyor belt  16  against the steam chest  12 , which can destroy the conveyor belt. This potential for tilting is solved by the stabilizers described below.  
         [0035]    [0035]FIG. 3 is a plan view of a pressure applicator structure for a machine for manufacturing corrugated board  10  including a first type of stabilizer for preventing a pair of pressure applicators from tilting. The stabilizer includes a first support structure  30 , such as a stabilizer bracket in the form of an “L” bracket, attached to the left end pressure applicator  22 , and a second support structure  32  attached to the right end pressure applicator  24 . To prevent these pressure applicators from tilting, a stabilizer strap  34  connects the left end support structure  30  to the right end support structure  32 . The support structure typically includes a support plate, such as a vertical section of an “L” bracket, or any other suitable type of support structure. For example, the support structure may include a vertical bar, a rod, a flange or any other type of structure that can be coupled to the pressure applicators and constrained to prevent the pressure applicators from tilting. In addition, the stabilizer strap  34  may be any suitable type of flexible or rigid connector. For example, the stabilizer strap  34  may be a flexible connector such as a cord, cable, chain, or canvas band. Alternatively, the stabilizer strap  34  may be a rigid connector, such as a bar, a rod, or any other type of connector that can effectively couple the support structures  30  and  32  to each other to prevent the pressure applicators  22  and  24  from tilting.  
         [0036]    [0036]FIG. 4 is a plan view of a pressure applicator structure for the machine  10  including a second type of stabilizer. This stabilizer includes first support structure  30  attached to the left end pressure applicator  22  and a second support structure  32  attached to the right end pressure applicator  24 . The support structure  30  is constrained from tilting by alignment members  40 , such as one or more alignment blocks or one or more rollers, supported by the support bar  18  and positioned adjacent to one or more support surfaces. For example, the support surfaces in this embodiment are defined by the left side edge of the support structure  30 . This allows the left end pressure applicator  22  with the attached support structure  30  to move vertically with respect to the support bar  18  while preventing the pressure applicator  22  from tilting. Similarly, the support structure  30  may also be constrained from tilting by alignment members  42 , which are supported by the support bar  18  and positioned adjacent to the right side edge of the support structure  30 .  
         [0037]    It should be appreciated that, because narrow board may be invariably run through the center of the machine  10 , a particular pressure applicator can only tilt in one direction. That is, each pressure applicator can only tilt away from the center of the machine as shown in FIG. 2B. Therefore, each stabilizer may include only a single alignment member, such as the alignment member  40  shown in FIG. 4. However, a design preference may include alignment members on both sides of a pressure applicator, as illustrated by alignment members  40  and  42  in FIG. 4. The alignment members may be implemented as any type of structure that allows the support structure to move vertically with respect to the support bar while preventing the pressure applicator from tilting. For example, the alignment members  40  and  42  may be blocks or rollers, such as wheels, cam followers, bearings or any other suitable type of rollers. In addition, an alignment member may include one, two, or more blocks or rollers located adjacent to a support surface, and each pressure applicator may include stabilizers on one or both sides of a support structure. When rollers are deployed as the alignment members, the rollers may be mounted on axels supported by the support bar  18  and positioned adjacent to a corresponding support surface. A similar type of stabilizer structure may be deployed for any number of pressure applicators, as desired.  
         [0038]    [0038]FIG. 5 is a perspective view of an illustrative pressure applicator  22  including a support structure  30  and alignment members  40  and  42  to prevent the pressure applicator from tilting. FIG. 5 illustrates a preferred configuration for the pressure applicator stabilizer shown to scale. The support bar  18  is configured to lift the pressure applicator  22  by lifting the support piers  20 , which are spanned by a connector  25 . More specifically, a lifting actuator  26 , in this instance an air cylinder, lifts the connector  25 , which in turn lifts the pressure applicator  22  by the support piers  20 . The support structure  30  is in the form of an “L” bracket, typically constructed from steel, which may be welded or bolted to the pressure applicator  22 . A vertical support plate  50  of the “L” bracket includes a left support surface  52  defined by a left edge of the support plate  50  and a right support surface  54  defined by a right edge of the support plate  50 .  
         [0039]    A first alignment member  40 , in this case an alignment block, is attached to the support bar  18  and positioned adjacent to the left support surface  52 . In addition, a second alignment member  42 , again an alignment block, is attached to the support bar  18  and positioned adjacent to the right support surface  54 . The alignment block may be constructed from steel, plastic, rubber or any other suitable material. This configuration allows the support structure  30  to move vertically with respect to the support bar  18  while preventing the pressure applicator  22  from tilting.  
         [0040]    [0040]FIG. 6 is a perspective view of a row of pressure applicators  13  including two stabilizers to prevent two pairs of pressure applicators at either end of the row from tilting. FIG. 6 illustrates a preferred configuration for the pressure applicator stabilizer of FIG. 3 shown to scale. More specifically, the row of pressure applicators  13  includes a left end pressure applicator  22  with an attached support structure  30 . The row of pressure applicators  13  also includes a right end pressure applicator  24  with an attached support structure  32 . A stabilizer strap  34 , which may be a flexible or rigid connector, couples the support structure  30  to the support structure  32  to prevent the pressure applicators  22  and  24  from tilting. Note that implementing the stabilizer strap  34  as a flexible connector, such as a cable or cord, only prevents the pressure applicators  22  and  24  from tilting away from the center of the row pressure applicators  13 . This is sufficient in most cases because narrow board may be run through the center of the row pressure applicators  13 . The row of pressure applicators  13  also includes a left second position pressure applicator  36  with an attached support structure  60  and a right second position pressure applicator  38  with an attached support structure  62 . A second stabilizer strap  64  couples the support structure  60  to the support structure  62  to prevent the pressure applicators  36  and  38  from tilting.  
         [0041]    [0041]FIG. 7 is a side view of a pressure applicator  22  including a stabilizer to prevent the pressure applicator from tilting. FIG. 7 illustrates a preferred configuration for the pressure applicator stabilizer of FIG. 4 shown to scale. FIG. 7 shows the support structure  30 , the support bar  18 , and the alignment members  40  in cross section from the side. In this embodiment, the alignment members  40  are implemented as rollers, such as cam followers.  
         [0042]    [0042]FIG. 8 is a front view of a pressure applicator  22  including a stabilizer with two rollers to prevent the pressure applicator from tilting. FIG. 8 illustrates a preferred configuration for the pressure applicator stabilizer of FIG. 4 shown to scale. FIG. 8 shows the support structure  30 , the support bar  18 , and the alignment members  40  and  42  from the front. Again in this embodiment, the alignment members  40  and  42  are implemented as rollers. In particular, the support structure  30  of this embodiment includes support plate  50  including a left support surface  52  defined by the left edge of the support plate  50  and a right support surface  54  defined by the right edge of the support plate  50 . The alignment member  40  include a first roller located adjacent to the left support surface  52 , and the alignment member  42  includes a second roller located adjacent to the right support surface  52 .  
         [0043]    [0043]FIG. 9 shows the same configuration as FIG. 8 except that the alignment member  40  include two roller located adjacent to the left support surface  52 , and the alignment member  42  includes one roller located adjacent to the right support surface  52 . FIG. 10 shows the same configuration as FIG. 8 except that the alignment member  40  include two roller located adjacent to the left support surface  52 , and the alignment member  42  includes two roller located adjacent to the right support surface  52 . Other variations to the disclosed embodiments of the invention will be readily apparent to those skilled in the art of corrugated board manufacturing.  
         [0044]    In view of the foregoing, it will be appreciated that present invention provides an improved machine for manufacturing corrugated board with pressure applicator stabilizers to prevent the pressure applicators from tilting. It should be understood that the foregoing relates only to the exemplary embodiments of the present invention, and that numerous changes may be made therein without departing from the spirit and scope of the invention as defined by the following claims.