Patent Publication Number: US-2020290235-A1

Title: Receiving table for honeycomb formed body, method for producing honeycomb formed body, and method for producing honeycomb fired body

Description:
FIELD OF THE INVENTION 
     The present invention relates to a receiving table for a honeycomb formed body, a method for producing a honeycomb formed body, and a method for producing a honeycomb fired body. 
     BACKGROUND OF THE INVENTION 
     As a method for forming a honeycomb formed body, an extrusion molding method is known. In the extrusion molding method, a honeycomb formed body is produced by attaching a mold (die) having a desired shape to an extrusion outlet of an extruder in which an extrusion direction is set in a horizontal direction, and continuously extruding a ceramic material fed to the extruder from the mold (die). The honeycomb formed body is conveyed while holding its side surface parallel to a cell extending direction by a receiving table, and is subjected to processing such as cutting, drying, and firing to form a honeycomb structure. 
     As a receiving table for a conventional honeycomb formed body, for example, Patent Document 1 proposes to a receiving table that is obtained using a foamed body at a position where the honeycomb formed body is contacted and supported. Further, Patent Document 2 proposes to a receiving table having a support surface formed from a porous polyurethane cured product such as chemical wood. 
     CITATION LIST 
     
         
         Patent Document 1: Japanese Patent Application Publication No. 2002-103325 A 
         Patent Document 2: Japanese Patent Application Publication No. 2011-079254 A 
       
    
     SUMMARY OF THE INVENTION 
     The present invention provides a receiving table for supporting a side surface of a honeycomb formed body, the side surface being parallel to a cell extending direction, the receiving table comprising: 
     a body portion having a groove extending in one direction; 
     a support portion comprising: a flexible sheet substrate in contact with a surface of the groove of the body portion; and a foam layer attached to the flexible sheet substrate, the foam layer being brought into contact with the side surface of the honeycomb formed body; and 
     fixing members for fixing the support portion to the body portion, 
     wherein the support portion is provided in a non-adhesive state to the body portion. 
     Further, the present invention provides a method for producing a honeycomb formed body, the method comprising conveying a honeycomb formed body resulting from extrusion molding while supporting a side surface of the honeycomb formed body by the receiving table for the honeycomb formed body, the side surface being parallel to a cell extending direction. 
     Furthermore, the present invention provides a method for producing a honeycomb fired body, the method comprising firing the honeycomb formed body obtained by the method for producing the honeycomb formed body. 
     According to the present invention, it is possible to provide a receiving table for a honeycomb formed body, which can hold a side surface of the honeycomb formed body without deformation, and can also easily attach/detach and replace a support portion that is brought into contact with the side surface of the honeycomb formed body. 
     Also, according to the present invention, it is possible to provide a method for producing a honeycomb formed body and a method for producing a honeycomb fired body, which can hold a side surface of the honeycomb formed body without deformation, and can reduce production costs while increasing a production efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a receiving table for a honeycomb formed body according to an embodiment of the present invention. 
         FIG. 2  is a perspective view of a support portion for use in a receiving table for a honeycomb formed body according to an embodiment of the present invention. 
         FIGS. 3( a ) and 3( b )  are partially enlarged side views around a fixing member of a receiving table for a honeycomb formed body according to an embodiment of the present invention. 
         FIG. 4  is a schematic view for explaining a state where an extruded honeycomb formed body is delivered onto a receiving table and conveyed. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the receiving table of Patent document 1, the portion (groove) for contacting and supporting the honeycomb formed body is formed of the foamed body, but processing accuracy is lower due to characteristics of the foamed body. Therefore, there is a problem that it is difficult to form a contact support surface corresponding to the side surface of the honeycomb formed body. Further, since the foamed body gradually degrades due to contact with the honeycomb formed body, it is necessary to replace the foamed body. However, the receiving table of Patent Document 1 needs to prepare a foamed body having a groove, which causes problem that it takes labor for the replacing work. 
     On the other hand, the receiving table of Patent Document 2 allows the side surface of the honeycomb formed body to be held without deformation by using the porous polyurethane resin cured product having high processing accuracy. 
     However, the porous polyurethane resin cured product has a lower cushioning property than that of the foamed body, and hence requires stricter processing accuracy. However, there is a limit to increase the processing accuracy of the porous polyurethane resin cured product. In particular, a processing load required to finish the contact support surface corresponding to the side surface of the honeycomb formed body cannot be ignored. 
     The present invention has been made in order to solve the above problems. An object of the present invention is to provide a receiving table for a honeycomb formed body, which can hold the honeycomb formed body without deforming a side surface of the honeycomb formed body, and can also easily attach/detach and replace a support portion that is brought into contact with the side surface of the honeycomb formed body. 
     A further object of the present invention is to provide a method for producing a honeycomb formed body and a method for producing a honeycomb fired body, which can hold a side surface of the honeycomb formed body without deformation, and can reduce production costs while increasing production efficiency. 
     As a result of intensive studies to solve the above problems, the present inventors have found that a support portion having a flexible sheet substrate and a foam layer is provided on a surface of a body portion having a groove extending in one direction, thereby enabling a contact support surface of the foam layer suitable for holding the side surface of the honeycomb formed body to be easily obtained, and that a non-adhesive state created between the body portion and the support portion (the flexible sheet substrate) can lead to easy attachment/detachment and replacement of the support portion, and they have completed the present invention. 
     Hereinafter, embodiments according to the present invention will be specifically described with reference to the drawings. It is to understand that the present invention is not limited to the following embodiments, and various modifications and improvements, which will be within the scope of the present invention, may be made based on ordinary knowledge of a person skilled in the art, without departing from the spirit of the present invention. 
     (Receiving Table for Honeycomb Formed Body) 
       FIG. 1  is a perspective view of a receiving table for a honeycomb formed body according to an embodiment of the present invention. 
     As shown in  FIG. 1 , a receiving table  100  for a honeycomb formed body according to an embodiment of the present invention includes: a body portion  10 ; a support portion  20  provided on the body portion  10 ; and fixing members  30  for fixing the support  20  to the body portion  10 . 
     The body portion  10  has a groove  11  extending in one direction. A shape of the groove  11  is not particularly limited, and can be appropriately adjusted according to the shape and size of the honeycomb formed body to be held. For example, the groove  11  of the body portion  10  has substantially the same curvature (arc surface) as a lower half of a side surface parallel to a cell extending direction of the honeycomb formed body. Although  FIGS. 1 and 2  show examples of the groove  11  formed in the body portion  10  where a cross section perpendicular to the cell extending direction of the honeycomb formed body is circular, it is also applicable to honeycomb formed bodies having various cross-sectional shapes such as an oval shape and a racetrack shape. 
     The body portion  10  is preferably formed of a hard material in terms of increasing processing accuracy of the shape of the groove  11 . For the hard material, the body portion  10  is preferably formed of a hard resin in terms of weight reduction. 
     As the hard resin, resins known in the art can be used, and a porous polyurethane resin is preferably used. Examples of the porous polyurethane resin include chemical wood. Chemical wood is commercially available, and RAKU-TOOL® from RAMPF can be used. 
     The hard resin preferably has a Shore D hardness of from 40 to 70 HS. The use of the hard resin having a Shore D hardness in such a range can lead to formation of the groove  11  having a desired contour and straightness and having less variation in shape accuracy. If the Shore D hardness is less than 40 HS, the material becomes too soft, so that a cut portion is deformed during the cutting to result in difficulty in forming the groove  11  having desired shape accuracy. Further, the shape of the groove  11  may be deformed by the weight of the honeycomb formed body. On the other hand, if the Shore D hardness is more than 70 HS, the material becomes too hard, so that it takes a long time for cutting, and abrasion of a processing jig also increases, which may lead to an increase in processing costs. 
     As used herein, the “Shore D hardness” means a value measured in accordance with ISO 868. 
     The body portion  10  preferably has a density of from 0.1 g/cm 3  to 0.65 g/cm 3 , although not particularly limited thereto. The density of the body portion  10  of 0.1 g/cm 3  or more can ensure the hardness of the body portion  10 , so that the groove  11  having desired shape accuracy can be easily formed. On the other hand, the density of the body portion  10  of 0.65 g/cm 3  or less can prevent the body portion  10  from becoming too heavy, so that the receiving table  100  can be easily handled. 
     The support portion  20  provided on the body portion  10  includes: a flexible sheet substrate  21  in contact with a surface of the groove  11  of the body portion  10 ; and a foam layer  22  attached to the flexible sheet substrate  21  and brought into contact with the side surface of the honeycomb formed body. The support portion  20  is curved following the groove  11  of the body portion  10 . 
     Here,  FIG. 2  shows a perspective view of the support portion  20  (in a state before being mounted on the receiving table  100  for the honeycomb formed body) used for the receiving table  100  for the honeycomb formed body. 
     As shown in  FIG. 2 , the support portion  20  has a simple laminated sheet structure in which the foam layer  22  is provided on the flexible sheet substrate  21 . 
     The support portion  20  is provided in a non-adhesive state to the body portion  10 . Therefore, when the foam layer  22  brought into contact with the side surface of the honeycomb formed body are degraded over a time of use, reuse is possible by replacing only the support portion  20  having the simple laminated sheet structure. 
     The shape and size of the support portion  20  are appropriately set according to the shape and size of the groove  11  of the body portion  10 . For example, the support portion  20  has a rectangular sheet shape having a length (L 1 ) in a direction where the groove  11  extends and a length (L 2 ) of the surface of the groove  11  perpendicular to the direction where the groove  11  extends. 
     The foam layer  22  may be provided over the entire surface of the flexible sheet substrate  21  or may be provided on a part of the surface of the flexible sheet substrate  21 . For example, as shown in  FIG. 2 , the foam layer  22  may not be provided at one both end portions of the flexible sheet substrate  21  (both end portions of L 2 ) in terms of facilitating the fixing of the support portion  20  by fixing member  30  (L-shaped angles  31 ) as described later. 
     The flexible sheet substrate  21  is not particularly limited as long as it can be curved following the groove  11  of the body portion  10 . Examples of the flexible sheet substrate  21  include a flexible resin sheet substrate, a graphite sheet substrate, and the like. The flexible resin sheet substrate is preferably used in terms of cost. The flexible resin sheet substrate is formed of a flexible resin. Examples of the flexible resin include a PP resin, a PET resin, a PC resin, and an acrylic resin. The PP resin is preferably used. 
     A thickness of the flexible sheet substrate  21  is not particularly limited as long as it does not impair flexibility. It is preferably from 0.1 to 1.0 mm. When the thickness is within such a range, the flexible sheet substrate  21  can be stably curved following the groove  11  of the body portion  10 . 
     The foam layer  22  is not particularly limited as long as it can be curved following the groove  11  of the body portion  10  together with the flexible sheet substrate  21 . Examples of the foam layer  22  include a layer formed of a resin foam (hereinafter, referred to as a “resin foam layer”) and a layer formed of a rubber foam (hereinafter, referred to as a “rubber foam layer”). Examples of the resin foam include a polyethylene foam, a urethane foam, a silicone foam, an acrylic foam, a polyvinyl chloride foam and the like. Examples of the rubber foam include a urethane rubber foam, a nitrile rubber foam, a chloroprene rubber foam, an ethylene rubber foam, a silicone rubber foam, and a fluoro rubber foam. These foams can be used alone or in combination of two or more. 
     The foam layer  22  preferably has open cells. The open cells have a higher cushioning property than that of closed cells, so that the honeycomb formed body can be held without deforming the side surface. 
     The foam layer  22  preferably has a density of from 10 to 40 g/cm 3 , and more preferably from 10 to 30 g/cm 3 , and still more preferably from 10 to 15 g/cm 3 , although not particularly limited thereto. The controlling of the density of the foam layer  22  within the above range can result in the foam layer  22  having flexibility and elasticity suitable for holding the side surface of the honeycomb formed body. 
     The contact surface of the foam layer  22  preferably has a 25% hardness of 130 N or less, and more preferably 60 N or less, although not particularly limited thereto. The controlling of the 25% hardness of the contact surface within the above range can result in the foam layer  22  having a contact surface with a hardness suitable for holding the side surface of the honeycomb formed body. 
     As used herein, the 25% hardness of the contact surface of the foam layer  22  means a hardness at the time of 25% compression measured in accordance with JIS K6401: 2011. More particularly, it is a load value (Newton) when the foam layer  22  is compressed once to 75% of its initial thickness (original thickness), and the foam layer  22  then returns to the original thickness, and the foam layer  22  is then pressed to 25% of the original thickness and maintained for 20 seconds. 
     The foam layer  22  preferably has a thickness of from 10 to 20 mm, although not particularly limited thereto. The thickness of the foam layer  22  of 10 mm or more can sufficiently ensure the cushioning property (impact absorbing power) of the foam layer  22 . On the other hand, the thickness of the foam layer  22  of 20 mm or less can curve the foam layer  22  following the groove  11  of the body portion  10  together with the flexible sheet substrate  21 . 
     The flexible sheet substrate  21  and the foam layer  22  are attached together using an adhesive or a double-sided adhesive tape. Among them, the flexible sheet substrate  21  and the foam layer  22  may preferably be attached together using the double-sided adhesive tape. This is because when the adhesive is used, the adhesive may enter bubbles of the foam layer  22 , thereby deteriorating the cushioning property of the foam layer  22 . 
     The fixing member  30  is not particularly limited as long as it is a jig capable of fixing the support portion  20  to the body portion  10 . 
     Here,  FIGS. 3( a ) and 3( b )  show partially enlarged side views around the fixing member  30  (a partially enlarged cross-sectional view of an end face perpendicular to a direction where the groove  11  of the body portion  10  extends). 
     Each fixing member  30  can include an L-shaped angle  31  that comes into contact with both an upper surface  12  of the body portion  10  and the flexible sheet substrate  21  of the support portion  20 , for example as shown in  FIGS. 1 and 3 . 
     Each L-shaped angle  31  is provided to prevent the support portion  20  from moving along the groove  11  of the body portion  10 . The L-shaped angle  31  can fix the support portion  20  by sandwiching the flexible sheet substrate  21  between the L-shaped angle  31  and the groove  11  of the body portion  10  and tightening them with bolts  32   a  or the like. 
     Further, as shown in  FIGS. 1 and 3 , the fixing members  30  can include opening/closing plates  33  provided on two end faces  13  perpendicular to the direction where the groove  11  of the body portion  10  extends. 
     Each opening/closing plate  33  is provided to prevent the support portion  20  from moving in a direction parallel to the direction where the groove  11  of the body portion  10  extends. As shown in  FIG. 3( a ) , each opening/closing plate  33  is closed by sliding on the end face  13  and is fixed with a bolt  32 b or the like, so that the support portion  20  can be fixed between the two end faces  13 . Further, as shown in  FIG. 3( b ) , each opening/closing plate  33  can be opened by loosening the bolt  32   b  and sliding on the end face  13 , so that the support portion  20  can be removed from the end face  13  side. 
     The receiving table  100  for the honeycomb formed body, which has the above structure, ensures a shape for holding the side surface of the honeycomb formed body by the groove  11  of the body portion  10 , and maintain the cushioning property by the foam layer  22  of the support portion  20  provided on the groove  11 , so that the honeycomb formed body can be held without deforming the side surface. Further, the support portion  20  has a simple laminated sheet structure in which the foam layer  22  is provided on the flexible sheet substrate  21 , and is also in a non-adhesive state between the body portion  10  and the support portion  20 . Therefore, when the foam layer  22  of the support portion  20  that comes into contact with the side surface of the honeycomb formed body is degraded, only the support portion  20  needs to be replaced and it does not take labor for the replacing work. 
     (Method for Producing Honeycomb Formed Body and Honeycomb Fired Body) 
     A method for producing a honeycomb formed body according to an embodiment of the present invention conveys the honeycomb formed body while supporting the side surface parallel to the cell extending direction of the honeycomb formed body resulting from extrusion molding by the above receiving table  100  for the honeycomb formed body. 
       FIG. 4  is a schematic view for explaining a state where the extruded honeycomb formed body is delivered to the receiving table  100  and conveyed. 
     As shown in  FIG. 4 , a honeycomb formed body  50  extruded from a die  41  of an extruder  40  is delivered to the receiving table  100  arranged on a conveying path  42  located upstream in an extrusion direction of the extruder  40 . At this time, it is preferable that an extrusion speed of the honeycomb formed body  50  and a speed of the conveying path  42  are substantially the same in order to smoothly deliver the honeycomb formed body  50  onto the receiving table  100 . The conveying path  42  is not particularly limited, but it is preferably a conveyor system having a belt  43  and rollers  44 . 
     The receiving table  100  holding the honeycomb formed body  50  is conveyed on the conveying path  42  in the conveying direction. A cutting unit for the honeycomb formed body  50  may be provided in the middle of the conveying path  42 . As the cutting unit for the honeycomb formed body  50 , a cutting jig  46  having a wire hung between a pair of bobbins  45  can be used. For example, the honeycomb formed body  50  can be cut by lowering the cutting jig  46  provided above the conveying path  42 . 
     The cut honeycomb formed body  50  is then subjected to a drying process and optionally a process such as plugging. The honeycomb formed body  50  can be then placed in a firing furnace and fired to form a honeycomb fired body. 
     The firing temperature is appropriately set according to the raw materials used for producing the honeycomb formed body  50 . For example, when the honeycomb formed body  50  is produced using a cordierite forming raw material, the firing temperature is preferably from 1380 to 1450° C., and more preferably from 1400 to 1440° C. The firing time for maintaining the firing temperature is generally from 3 to 10 hours, although not particularly limited thereto. 
     The method for producing the honeycomb formed body  50  by extrusion molding is not particularly limited, and can be carried out according to a known method. For example, a green body containing ceramic powder, a binder, water and the like may be charged into the extruder  40  and extruded. 
     Examples of the ceramic powder include cordierite forming raw materials, silicon carbide, mullite, alumina, aluminum titanate, silicon nitride, cordierite-silicon carbide composite materials, lithium aluminum silicate, metallic silicon, or mixtures thereof. These can be used alone or in combination of two or more. The cordierite-forming raw material means a material that is converted into cordierite by firing, including, for example, materials obtained by mixing talc, kaolin, alumina, aluminum hydroxide, and/or silica such that a composition after firing is a theoretical composition of cordierite (2MgO.2Al 2 O 3 .5SiO 2 ). The cordierite forming raw material typically has a composition containing from 40 to 60% by mass of silica, from 15 to 45% by mass of alumina, and from 5 to 30% by mass of magnesia. 
     Examples of the binder include, but not particularly limited to, organic binders such as agar, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. These can be used alone or in combination of two or more. 
     The shape of the honeycomb formed body  50  produced by the extruder  40  is not particularly limited, and it is appropriately set depending on applications to be used. 
     The honeycomb formed body  50  produced by the extruder  40  has partition walls that define cells extending in the extrusion direction. The shape of each cell in a cross section perpendicular to the cell extending direction of the honeycomb formed body  50  may be various shapes such as a circle, an ellipse, and a polygon such as a triangle to an octagon, although not particularly limited thereto. The outer shape of the cross section perpendicular to the cell extending direction of the honeycomb formed body  50  may be various shapes such as a circular shape, an oval shape, and a racetrack shape, although not particularly limited thereto. 
     The number of cells per cm 2  in the cross section perpendicular to the cell extending direction of the honeycomb formed body  50  is preferably from 30 to 180, and more preferably from 30 to 150, and even more preferably from 30 to 93, and most preferably from 30 to 62, although not particularly limited thereto. 
     The thickness of each partition wall in the cross section perpendicular to the cell extending direction of the honeycomb formed body  50  is preferably from 0.05 to 0.30 mm, and more preferably from 0.05 to 0.10 mm, and even more preferably from 0.1 to 0.10 mm, and still more preferably from 0.05 to 0.08 mm, although not particularly limited thereto. The partition wall thickness can be measured by, for example, an image analyzer (trade name “NEXIV, VMR-1515” from Nikon Corporation). 
     A width of the honeycomb formed body  50  in the cross section perpendicular to the cell extending direction (a diameter for the circular shape, and a diameter of the longest portion for the ellipse shape or the like) is preferably 70 cm or more, and more preferably 115 cm, and even more preferably 170 cm or more, although not particularly limited thereto. 
     The honeycomb formed body  50  having the number of cells, the partition walls, and the width as described above tends to generate local deformation in the partition walls on the inner side of the honeycomb formed body, rather than in the partition walls on the outer periphery of the honeycomb formed body  50 , when the honeycomb formed body  50  comes into contact with the receiving table  100 . 
     However, by using the receiving table  100  according to the embodiment of the present invention, the local deformation can be suppressed, so that a decrease in yield can be suppressed. 
     The honeycomb formed body  50  having the above shape can be obtained by appropriately setting the structure of the die  41  provided at the tip of the extruder  40 . 
     The honeycomb formed body  50  and the honeycomb fired body produced as described above are produced using the receiving table  100  for the honeycomb formed body  50 , which can hold the side surface of the honeycomb formed body  50  without being deformed, and easily detach/attach the support portion  20  that is brought into contact with the side surface of the honeycomb formed body  50 , so that the side surface of the honeycomb formed body  50  is not deformed, and the production costs can be reduced while increasing the production efficiency. 
     The honeycomb fired body produced as described above can be used for various applications such as catalyst supports for purifying automobile exhaust gases, diesel particulate removal filters, gasoline particulate removal filters, and heat storage bodies for combustion devices. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           10  body portion 
           11  groove 
           12  upper surface 
           13  end face 
           20  support portion 
           21  flexible sheet substrate 
           22  foam layer 
           30  fixing member 
           31  L-type angle 
           32   a,    32   b  bolt 
           33  opening/closing plate 
           40  extruder 
           41  die 
           42  conveying path 
           43  belt 
           44  roller 
           50  honeycomb formed body 
           100  receiving table