Abstract:
Disclosed apparatus and method to extrude a honeycomb, providing correction in bowing of the extruded honeycomb structure, employs a deflector device having a base plate including an opening aligned in a direction parallel to the extrusion axis through which the plastic material is conveyed to the die. The deflector device includes a bow plate movably mounted to the downstream or upstream side of the base plate. The bow plate includes a constant area aperture. The deflector device positioned upstream of extrusion die imparts a degree of bow reduction by the position of the constant area aperture over the opening imparting a pressure drop gradient on the flow stream entering the die.

Description:
BACKGROUND 
     1. Field 
     Exemplary embodiments of the present disclosure relate to extrusion of plastic batches, and more particularly to a device and method for overcoming the problem of bow in a honeycomb extrudate. 
     2. Discussion of the Background 
     Ceramic honeycombs for gasoline and diesel exhaust treatment applications can be produced by cutting and firing individual pieces from a stream of honeycomb extrudate, or by cutting the pieces from a dried green or fired ceramic “log” of extrudate which may be of meter or greater length. To meet customer requirements for the subsequent catalyst coating and “canning” of these ceramic honeycombs in suitable metal enclosures, it is important that the logs and pieces cut from the logs have sides which are straight and parallel. 
     The production of a straight stream of extruded material can be difficult; in most cases at least some “bowing” of the extrudate, attributable to uneven flow of material through the extrusion die, is observed. This bowing can be caused by non-uniform flow characteristics in the batch, but more commonly is due to uneven flow resistance across the face of the extrusion die. Even with careful attention to die fabrication, uneven machining resulting from facts such as progressive tool wear, misalignment of feed holes and discharge slots, and non-uniform exposure to chemical machining and/or plating electrolytes can result in at least some bowing tendency being “built in” to most honeycomb extrusion dies during manufacture. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form any part of the prior art nor what the prior art may suggest to a person of ordinary skill in the art. 
     SUMMARY 
     Exemplary embodiments of the present disclosure provide a bow deflector device. 
     Exemplary embodiments of the present disclosure also provide a honeycomb extrusion apparatus comprising the bow deflector device. 
     Exemplary embodiments of the present disclosure also provide a method for forming a honeycomb structure using the bow deflector device. 
     Additional features of the disclosure will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the disclosure. 
     An exemplary embodiment discloses a bow deflector device positioned upstream of an extrusion die, the bow deflector device includes a base having an aperture of a first constant area to pass a feed stream of plastic batch material therethrough. A bow plate is movably mounted to a downstream or upstream side of the base. The bow plate includes an opening of a second constant area less than the first constant area to pass the feed stream of plastic batch material therethrough. By adjusting the bow plate position on the base, bow in a honeycomb extrudate extruded from the extrusion die can be corrected in any direction to “true zero” magnitude. 
     An exemplary embodiment also discloses a method for forming a honeycomb structure. The method includes providing a plastic batch material, directing a feed stream of the plastic batch material along an extrusion path through a bow deflector device. The bow deflector device includes a base having an aperture of a first constant area to pass the feed stream of plastic batch material therethrough, and a bow plate movably mounted to a downstream or upstream side of the base, the bow plate comprising an opening of a second constant area less than the first constant area to pass the feed stream of plastic batch material therethrough. By passing through the bow deflector device a unique flow velocity is superimposed on the feed stream of plastic batch material, as determined by the diameter of the opening, and the position of the opening. The method directs the feed stream of plastic batch material with the superimposed flow velocity through a honeycomb extrusion die, wherein the superimposed flow velocity corrects bow in any direction to “true zero” magnitude. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure, and together with the description serve to explain the principles of the disclosure. 
         FIG. 1  presents a sectional view showing a die, a skin-forming member, and an extrudate bow corrector. 
         FIG. 2  presents a perspective view illustration of components of a bow deflector device according to the prior art. 
         FIG. 3 . is a front view of the bow deflector device of  FIG. 2 . 
         FIG. 4 . is a perspective view of the components of a bow deflector device according to exemplary embodiments of the disclosure. 
         FIG. 5  is a front view of the bow deflector device of  FIG. 4 . 
         FIG. 6  is a cross sectional view of a honeycomb extrusion apparatus including the bow deflector device of  FIG. 5  sectioned along line VI-VI′. 
         FIG. 7  is a perspective view of the bow deflector device of  FIG. 4  illustrating the movable constant area opening of the bow plate in a top left position. 
         FIG. 8  is a perspective view of the bow deflector device of  FIG. 4  illustrating the movable constant area opening of the bow plate in a top right position. 
         FIG. 9  is a perspective view of the bow deflector device of  FIG. 4  illustrating the movable constant area opening of the bow plate in a center right position. 
         FIG. 10  is a perspective view of the bow deflector device of  FIG. 4  illustrating the movable constant area opening of the bow plate in a bottom center position. 
         FIG. 11  shows a graph of data of bow movement resulting from plate movement in the Comparative deflector device and the deflector device according to the exemplary embodiments of the disclosure having a single orifice bow plate. 
         FIG. 12  shows a graph of data of slide (shape) resulting from plate movement in the Comparative deflector device having shutter plates and the deflector device according to the exemplary embodiments of the disclosure having a single orifice bow plate. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the disclosure to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. It will be understood that when an element or layer is referred to as being “on”, “connected to”, or “adjacent to” another element or layer, it can be directly on, directly connected to, or directly adjacent to the other element or layer, or intervening elements or layers may be present. In contrast, when an element or layer is referred to as being “directly on”, “directly connected to”, or “directly adjacent to” another element or layer, there are no intervening elements or layers present. Like reference numerals in the drawings denote like elements. It will be understood that for the purposes of this disclosure, “at least one of X, Y, and Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ). 
       FIG. 1  shows a cross section of a honeycomb extrusion apparatus  10  that includes a die  12  and an extrudate bow corrector  14 . Examples of extrudate bow corrector devices for correcting bow in a stream of extruded material are provided in U.S. Pat. No. 6,663,378, issued Dec. 16, 2003, and U.S. patent application having Ser. No. 10/370,840 and Publication No. 2004-0164464, published Aug. 26, 2004, both of which are hereby incorporated by reference in their entirety as if fully set forth herein. The die  12  is composed of peripheral feed holes  16  and central feed holes  18  communicating at one end with an inlet face  20 , and at the other end with a plurality of interconnected peripheral discharge slots  22  and central discharge slots  24 , forming central pins  26  and peripheral pins  28  at an outlet face  30 . 
     The extrudate bow corrector  14  is positioned upstream of the die  12 , adjacent an optional peripheral feed flow device  32 . Examples of peripheral feed flow devices are provided in U.S. Pat. No. 6,991,448, issued Jan. 31, 2006, which is hereby incorporated by reference in its entirety as if fully set forth herein. The extrudate bow corrector  14  includes a base  34  having an aperture  36  (partially shown) sufficiently large for the batch material to pass therethrough. A plurality of adjustable plates  38  movably mounted to the base  34  may be provided, each adjustable plate  38  capable of being moved independently of the others at bolt  40 , such that when the adjustable plates are adjusted to varying positions a correction is simultaneously effected in the direction and magnitude of a bow in a honeycomb extrudate. A cover  42  may also be provided on the bow corrector  14 , the cover  42  being comparable size and shape to the base  34 . The cover  42  acts to shield the adjustable plates  38 , and can be securely mounted to the base  34 . The cover  42  can mirror the base  34  in size and shape, and include an aperture  44  (partially shown) of equal or greater diameter to the base aperture  36 . 
       FIG. 2  and  FIG. 3  illustrate a perspective view and a front view, respectively, of a bow deflector device  50 . In the provided drawings bow deflector device  50  includes a base  52  having an aperture  54  through which flow of a plasticized batch or extrudate is attained. Further, a plurality of adjustable plates  56  are movably mounted to base  52 . In  FIG. 2 , four adjustable plates ( 56   a - d ) are shown. The adjustable plates have at least one straight edge  57  adjacent the base aperture  54 . 
     Bolts  58  located on each adjustable plate  56   a - d , control the movement of the adjustable plates. By designing the movement of the adjustable plates  56   a - d  to be possible for an “in-and-out” motion, the adjustable plates  56   a - d  can be externally manipulated at openings  59 . This allows for external manipulation during production without interruption thereof. The plates  56   a - d  may be adjusted mechanically, for example by screws  58  as illustrated in  FIG. 2 , or pneumatically or by a hydraulic device (not shown). Each adjustable plate  56   a - d  is independent in movement from the others. Changing the positions of one or more of the adjustable plates  56   a - d , not only affects the direction, but also the magnitude of bowing that can be corrected. 
     The degree of bow correction flexibility is dictated by the aperture  54  in base  52 . In the maximum-correction position the adjustable plates  56   a - d  are moved to reduce the diameter of the aperture  54  to the smallest possible opening. In the minimum-correction position the adjustable plates  56   a - d  are moved to allow for the maximum diameter of aperture  54 . 
     The position of the adjustable plates  56   a - d  can be selected to achieve desired magnitude of bow correction, in any direction. For example, referring to  FIG. 3 , plates  56   a , and  56   d  are adjusted to an intermediate position to correct down and right bow for a predetermined degree of bow correction. The deflector device can include a cover  60  which overlays the adjustable plates  56   a - d , and is securely mounted to base  52 . The mounting is attained with dowel pins  64  at corresponding holes  66  on both the base  52  and cover  60 . Cover  60  is also provided with an aperture  62 , having a diameter of equal to or greater than the diameter of aperture  54  on the base  52 . 
     The bow deflector device  50  having the adjustable plates  56   a - d  is relatively effective at general bow control, but can drive other attributes, particularly shape due to the “choking off” the flow in a non-uniform manner, and changing both the size and shape of the batch flow going to the back of the die  12  ( FIG. 1 ). 
       FIG. 4  illustrates a perspective view of a bow deflector device according to exemplary embodiments of the disclosure. The bow deflector device  100  in  FIG. 4  can include a base  112 , a horizontal adjustment member  114 , a horizontal connector  116 , a vertical adjustment member  124 , a vertical connector  126 , and a bow plate  130 . 
     The bow deflector base  112  has an aperture  132  through which flow of a plasticized batch or extrudate is attained. The bow plate  130  is movably mounted to base  112 . The bow plate  130  may be movably mounted to the downstream or upstream side of the base  112 . The bow plate  130  has an opening  134  defined by edge  135  adjacent the base aperture  132 . The opening  134  can be directly adjacent the base aperture  132 . The opening  134  is a constant area and can be the same shape as the product being extruded. The opening  134  can be of the same or different size of the aperture  132 , for example, the opening  134  can be smaller in size than the aperture  132 . The bow plate  130  blocks extrudate flow except extrudate flow through opening  134 . 
     Horizontal adjustment member  114  located on a side of the base  112 , controls a horizontal movement of the bow plate  130 . The horizontal adjustment member  114  can be connected to a side of the bow plate  130  by a horizontal connector  116 . For example, the horizontal adjustment member  114  may be a bolt and the horizontal connector  116  may be a rider block. In another example, the horizontal adjustment member  114  may be a bolt that pushes directly on outer peripheral edge  136  of bow plate  130 . Vertical adjustment member  124  located on a top of the base  112  in  FIG. 4 , controls a vertical movement of the bow plate  130 . The vertical adjustment member  124  can be connected to a top of the bow plate  130  by a vertical connector  126 . For example, the vertical adjustment member  124  may be a bolt and the vertical connector  126  may be a rider block. In another example, the vertical adjustment member  124  may be a bolt that pushes directly on outer peripheral edge  136  of bow plate  130 . The horizontal and vertical adjustment members  114 ,  124  can be externally manipulated at openings  137 ,  139 , respectively. This allows for external manipulation during production without interruption thereof. The adjustment members  114 ,  124  may be adjusted mechanically, for example rotation of screw threads on bolts as illustrated in  FIG. 4 , or by pneumatic or hydraulic devices (not shown). 
     While terms, top, side, vertical, and horizontal are used, the disclosure is not so limited to these exemplary embodiments. Instead, spatially relative terms, such as “top”, “bottom”, “horizontal”, “vertical”, “side”, “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated  90  degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Thus, the exemplary term “side” can become “top” and vice versa when the bow deflection device  100  in  FIG. 4  is rotated 90 degrees counter clockwise. 
     The horizontal and vertical connectors  116 ,  126  connect to the side and top of the bow plate, respectively, to move the plate in response to in-and-out movement of horizontal and vertical adjustment members  114 ,  124 . Alternatively, as described above, the horizontal and vertical connectors  116 ,  126  can be omitted and the horizontal and vertical adjustment members  114 ,  124  can contact the bow plate  130  directly, such as, by pushing on peripheral edge  136 . The horizontal connector  116  can be connected to the bow plate  130  by fastener pins  142  in vertical slot  143  and the vertical connector  126  can be connected to the bow plate  130  by fastener pins  144  in horizontal slot  145 . Movement of horizontal adjusting member  114  in-and-out relative to center of aperture  132  of the base  112  in opening  137 , causes fastener pins  142  in vertical slot  143  to correspondingly move bow plate  130  in a horizontal direction. When bow plate  130  moves in a horizontal direction, fastener pins  144  move in horizontal slot  145  of the bow plate  130 , for example, fastener pins  144  may slide in horizontal slot  145 . When bow plate  130  moves in a horizontal direction, opening  134  moves in a horizontal direction. 
     Likewise, vertical adjustment member  124  movement in and out relative to center of aperture  132  of the base  112  in opening  139 , causes fastener pins  144  in horizontal slot  145  to correspondingly move bow plate  130  in a vertical direction. When bow plate  130  moves in a vertical direction, fastener pins  142  move in vertical slot  143  of the bow plate  130 , for example, fastener pins  142  may slide in vertical slot  143 . When bow plate  130  moves in a vertical direction, opening  134  moves in a vertical direction. Accordingly, opening  134  can move horizontally and vertically relative to the base  112  while maintaining a constant opening size (area) and shape. Changing the position of opening  134 , not only affects the direction, but also the magnitude of bowing that can be corrected. 
     It will be evident that the vertical adjustment member  124  and horizontal adjustment member  114  are orthogonal to one another to operably manipulate the opening  134  to positions relative to the base  112  aperture  132 . However, the vertical adjustment member  124  and horizontal adjustment member  114  may be at various positions to one another to accomplish similar manipulations of the opening  134  to positions relative to the base  112  aperture  132 . 
     The position of the bow plate  130  can be selected to achieve desired magnitude of bow correction, in any direction. For example, referring to  FIG. 5 , bow plate  130  is adjusted to an intermediate position to correct down and right bow for a predetermined degree of bow correction. The deflector device  100  can include a cover  150  which overlays the adjustable bow plate  130 , and is securely mounted to base  112 . The mounting is attained with dowel pins  154  at corresponding holes  156  on both the base  112  and cover  150 . Cover  150  can also be provided with an aperture  152 , having a diameter of equal to or greater than the diameter of aperture  132  on the base  112 . 
       FIG. 6  shows a cross section view through the bow deflector device  100  of  FIGS. 4 and 5 . A batch flow direction is indicated by arrow “A”. In operation the bow deflector device  100  can be positioned upstream of a honeycomb extrusion die  12  in an apparatus  200  for the extrusion of a honeycomb structure according to the present disclosure. The honeycomb extrusion die  12  employed in the apparatus has an inlet face  20  comprising a plurality of feed holes  18 , and an outlet face  30  comprising discharge slots  24 . The discharge slots  24  are configured to produce an extrudate of honeycomb configuration from a plastic batch flowing downstream through the die along an extrusion axis parallel with the direction of extrusion. 
     The extrudate flows through the bow deflector device  100  prior to entering and passing through the die  12 . As the plastic batch flows through the die, it does so having a unique flow velocity superimposed thereon as determined by the peripheral edge  135  of the opening  134  of the bow plate  130 , and the position of the opening  134 . This flow velocity gradient counteracts preferential flow in the die, resulting in equal batch flow throughout the die. Therefore, as the honeycomb extrudate emerges from the die it is absent of any bow in any direction. The bow deflector device  100  can be directly adjacent the die  12  or other intervening extrusion hardware devices may be present, such as a flow control device. For example, in  FIG. 6 , peripheral feed flow device  32  is illustrated disposed between the bow deflector device  100  and the die  12 . 
     The bow plate  130  can move anywhere within the constraints of the base  112  by adjustment of vertical and horizontal adjustment members  114 ,  124 .  FIG. 7  shows the bow plate  130  and bow plate opening  134  in an upper left position to counter upper left bow in the extrudate.  FIG. 8  shows the bow plate  130  and bow plate opening  134  in an upper right position to counter upper right bow in the extrudate.  FIG. 9  shows the bow plate  130  and bow plate opening  134  in a right position and  FIG. 10  shows the bow plate  130  and bow plate opening  134  in a bottom position to counter right bow and downward bow, respectively, in the extrudate. For example, the bow plate  130  and bow plate opening  134  can move to the positions shown in  FIGS. 7 to 10  by turning bolts of the vertical and horizontal adjustment members  114 ,  124 . When moved, the size and shape of the opening  134  remains unchanged. 
     The opening  134  can be positioned to provide the most effective flow correction as required to provide for a straight extrudate, to counter the issues that prevent it from being straight naturally, with minimal impact on cross sectional shape of the extrudate. For example, when the extrudate cross sectional shape is an ellipse, the opening  134  can be an ellipse, or when the extrudate cross sectional shape is a circle, the opening  134  can be a circle. The bow plate  130  being a unitary structure provides a constant area and constant shape opening  134  at all times according to these exemplary embodiments. For example, the unitary structure can be a single plate. For example, when the bow plate  130  moves from a first location in aperture  132  to a second location in aperture  132 , and at all positions between the first location and the second location, opening  134  maintains a constant area and constant shape. 
       FIG. 11  shows a graph of data of bow movement resulting from plate movement in the Comparative deflector device  50  having shutter plates  56   a - d  (C) and the deflector device  100  according to the exemplary embodiments of the disclosure having a single orifice bow plate  130  (E) for left (L), right (R), and centered (Center) positions. The bow plate  130  having the constant area opening  134  provides as much or more bow control capabilities as the Comparative deflector device  50  having shutter plates  56   a - d.    
       FIG. 12  shows a graph of data of slide (shape) resulting from plate movement in the Comparative deflector device  50  having shutter plates  56   a - d  (C) and the deflector device  100  according to the exemplary embodiments of the disclosure having a single orifice bow plate  130  (E).  FIG. 12  shows the average slide left to right by condition. The testing was conducted to demonstrate impact of extruded body shape with plate movement. Centered (Center), maximum right (R) and maximum left (L) are shown. The bow plate  130  having the constant area opening  134  provides better slide (“nose” on one side of extruded part) for improved shape capability. 
     Advantages of the extrusion apparatus provided in accordance with the present disclosure include: (1) correction of bow in any direction to true “zero” magnitude; (2) bow correction during the manufacturing process without interruption in production due to “external manipulation” design in the bow deflector device; (3) reduction of swollen webs in peripheral zone of extruded honeycomb substrates; (4) compatible with extrusion of thin and ultra-thin honeycomb substrates; (5) reduction in preferential flow in conventional dies; (6) reduction in hardware costs; and, (7) increased product output as a result of decreasing bow-related failure. 
     According to exemplary embodiments of the disclosure, further advantages include: (8) simpler and easier to assemble hardware; (9) reduction in control (adjustment) members from one at each 90 degree position to only a side and top control making the bow deflector device both simpler to operate and safer since these control locations can be positioned at the easiest locations to access; (10) elimination of joints between individual shutter plates, the bow plate virtually eliminates joints as a source of leakage; (11) allows more movement flexibility for 2-directional bow control because the bow plate can move opening into the 45 regions as needed; (12) ease of tracking opening movement (position of opening), for example, because two controls instead of four that can lead to more direct automation of bow control movement and improved bow control via faster reaction and incremental movement; (13) ease of disassembly and cleaning; (14) easily add to existing extrusion hardware designs with less cost; (15) avoids impact on extrudate shape by avoiding the “choking off” of the flow in a non-uniform manner; and (16) maintains constant size and shape of the batch flow going to the back of the die. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the disclosure. Thus, it is intended that the appended claims cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.