Honeycomb structure forming tool

Abstract

Honeycomb structure forming tool (100, 300) comprising: a first mold (10) disposed on an upstream side in an extrusion direction (X) of a kneaded material of a molding raw material, and in which a central portion (15) on the side of a kneaded material discharge surface (18) has a convex portion (16) projecting toward a downstream side in the extrusion direction (X); and an annular second mold (20) arranged on the downstream side of the first mold (10) and having a shape complementary to the convex region (16), wherein first kneading material introduction holes (12) and first grid slots (11) communicating with the first kneading material introduction holes (12) are formed in the central region (15) of the first mold (10), in a peripheral region (17) surrounding the central region (15) of the first mold (10), the first kneading material introduction holes (12) are formed such that they extend through the peripheral region (17) of the first mold (10), second kneading material introduction holes (22) are formed in the annular second mold (20), into which the kneading material discharged from the first kneading material introduction holes (12) formed in the peripheral region (17) of the first mold (10) is introduced, and second grid slots (21) communicating with the second kneading material introduction holes (22), Positions of the opening of the first kneading material introduction holes (12) of the peripheral region (17) of the first mold (10) do not coincide with the positions of the openings of the second kneading material introduction holes (22) of the second mold (20) at least in a part of the honeycomb structure molding tool (100, 300), an abutment surface (14) of the first mold (10) is an end face of the peripheral region (17) of the first mold (10) on a downstream side with respect to the extrusion direction (X), and an abutment surface (24) of the second mold (20) is an end face of the second mold (20) on an upstream side with respect to the extrusion direction (X), and wherein the honeycomb structure forming tool (100, 300) comprises: a gap region (35) between an outer peripheral surface of the convex portion (16) of the first mold (10) and an inner peripheral surface of the annular second mold (20) for extruding the kneaded material into a ring shape, and a groove region (31) having a plurality of grooves formed in the abutting surface (14) of the first mold (10) and / or in the abutting surface (24) of the second mold (20), and in which the movement of the kneading material between the first kneading material introduction holes (12) and the second kneading material introduction holes (22) is carried out, wherein the abutting surfaces (14, 24) of the first mold (10) and the second mold (20) are in contact with each other except for a region in which the groove region (31) is formed.

Description

[0001] This application is an application based on JP-2016-156974, filed on August 9, 2016, and JP-2016-220871, filed on November 11, 2016, with the Japan Patent Office, the entire contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTIONField of the invention

[0002] The present invention relates to a honeycomb structure forming die, and more particularly, it relates to a honeycomb structure forming die capable of forming a honeycomb formed body having a central part different from a peripheral part in terms of honeycomb structure with high quality. Description of the state of the art

[0003] Conventionally, a catalyst-impregnated honeycomb structure is used for treatment to remove pollutants such as HC, CO, and NOx contained in exhaust gases emitted from an internal combustion engine of a motor vehicle or the like. Furthermore, in the honeycomb structure, plugs are attached to open ends of honeycombs formed by porous partition walls, thereby also using the honeycomb structure as a filter for exhaust gas purification.

[0004] Honeycomb structures are columnar structures each including partition walls forming a plurality of honeycombs that become flow channels for exhaust gas. Such a honeycomb structure has a honeycomb structure in which a plurality of honeycombs are regularly arranged in predetermined cycles in a plane perpendicular to an extending direction of the honeycombs. Heretofore, there has been one type of honeycomb structure in the above-mentioned plane of a honeycomb structure, but recently, for the purpose of improving the purification efficiency of exhaust gas or the like, a honeycomb structure having two or more types of honeycomb structures in the above-mentioned plane has been proposed.For example, a honeycomb structure has been proposed in which a central part is different from a peripheral part in a plane perpendicular to a honeycomb extending direction in honeycomb density or honeycomb shape, thus the honeycomb structure has two kinds of honeycomb structures in the above-mentioned plane.

[0005] This honeycomb structure is manufactured by molding a wrought material containing a ceramic molding raw material with an extrusion die to produce a honeycomb molded body, and then drying and firing the resulting honeycomb molded body. For example, the mold is manufactured as a honeycomb molding die by forming back holes into a metal molding substrate, into which the wrought material is inserted, and slits communicating with the back holes (see, for example, Patent Documents 1 to 4). Hereinafter, the honeycomb molding die is simply referred to as a "molding die" or occasionally as a "mold." [0004a] Further prior art is also known from Patent Document 5. [Patent Document 1] JP 2015- 096 310 A [Patent document 2] JP 2013- 132 879 A [Patent Document 3] JP 2013- 132 881 A [Patent Document 4] JP H04-332 604 A [Patent Document 5] US 6,039,908 A BRIEF DESCRIPTION OF THE INVENTION

[0006] For example, a mold described in Patent Document 1 includes a first mold part located on an upstream side in an extrusion direction of a raw material and a second mold part located on a downstream side. The above-mentioned first mold part has convex portions protruding from a periphery on the downstream side in the extrusion direction, and the above-mentioned second mold part has through holes that fit with the convex portions. In the mold described in Patent Document 1, the convex portions of the first mold part are inserted into the through holes of the second mold part to combine the first mold part and the second mold part into one mold.

[0007] However, the mold described in Patent Document 1 has a problem that there are design limitations when the mold for molding a honeycomb molded article is used to form a honeycomb structure having two types of honeycomb structures. In other words, usually, in the mold for molding the honeycomb molded article, "lattice slits" are formed on the side of a kneading material discharge surface of a molding substrate, which correspond to a honeycomb structure of the honeycomb molded article. Further, in such a mold, back holes are formed as raw material supply holes, which communicate with intersection points of the lattice slits. In Patent Document 1 described, in situations where the first mold part is different from the second mold part in terms of the shape of the respective slits, it is difficult to connect all the back holes (i.e., first raw material supply holes) in the first mold part with all the back holes (i.e.,second raw material supply holes) in the second mold part. If all the back holes do not coincide with each other, when the first mold part and the second mold part are combined into one piece, the movement of the molded material in the mold is hindered, and uniform extrusion becomes difficult. Therefore, in the mold described in Patent Document 1, it is necessary to select the shapes of the slits formed in the first mold part and the second mold part, respectively, so that the above-mentioned movement of the molded material is not hindered, and the degree of freedom of design is very low.

[0008] The molds described in Patent Documents 2 and 3, respectively, are not molds for forming a honeycomb formed article having two types of honeycomb structures, but are molds for improving honeycomb quality only in an outermost peripheral part. Furthermore, the molds described in Patent Documents 2 and 3 have a problem in that they are not compatible with the formation of various honeycomb formed articles in which the shapes of two types of honeycomb structures and their formation areas vary widely. For example, a honeycomb structure having two types of honeycomb structures occasionally has a boundary wall arranged to surround the honeycomb structure of a central part at a boundary between the honeycomb structure of the central part and the honeycomb structure of a peripheral part.During extrusion, the boundary wall requires a large amount of molding raw material compared to the partition walls constituting the honeycomb structures of the central part and the peripheral part. When the honeycomb formed body having such a boundary wall as described above is formed using any of the molds described in Patent Documents 2 and 3, the demand exceeds the supply of the molding raw material for forming the boundary wall, and molding defects may be caused in the boundary wall and its surroundings. Furthermore, the molds described in Patent Documents 2 and 3 were each developed to improve the honeycomb quality only in the outermost peripheral part, and thus a problem arises regarding the strength of a shell portion. If the problem is to be solved only by simply increasing the molding area of ​​a shell portion, there is a risk of the shell portion being deformed.

[0009] A mold described in Patent Document 4 has a structure in which adjacent mold bodies are tightened with wedges or engaged with each other using pressing pressure. Thus, there is a problem that the pressure resistance properties of a wrought material are low and the mold is prone to breakage. The mold described in Patent Document 4 also has a problem that positional displacement of back holes is easily caused and there is a likelihood of generating molding defects.

[0010] The present invention has been developed in consideration of the above-mentioned problems, and its object is to provide a honeycomb structure molding die capable of molding a honeycomb molded article having a central part different from a peripheral part in terms of honeycomb structure with high quality.

[0011] According to the present invention, the following honeycomb structure forming tool is provided.

[0012] [1] A honeycomb structure forming tool comprising: a first mold disposed on an upstream side in an extrusion direction of a kneaded material of a molding raw material, and in which a central portion on the side of a kneaded material discharge surface has a convex portion projecting toward a downstream side in the extrusion direction; and an annular second shape arranged on the downstream side of the first shape and having a shape complementary to the convex region, wherein first wrought material introduction holes and first grid slots communicating with the first wrought material introduction holes are formed in the central region of the first mold, in a peripheral region surrounding the central region of the first mold, the first wrought material introduction holes are formed so as to pass through the peripheral region of the first mold, second wrought material introduction holes are formed in the annular second mold, into which the wrought material discharged from the first wrought material introduction holes formed in the peripheral region of the first mold is introduced, and second grid slots communicating with the second wrought material introduction holes, and

[0013] Positions of the opening of the first kneading material introduction holes of the peripheral region of the first mold do not coincide with the positions of the openings of the second kneading material introduction holes of the second mold in at least a part of the honeycomb structure molding tool, an abutting surface of the first mold is an end surface of the peripheral portion of the first mold (10) on a downstream side with respect to the extrusion direction, and an abutting surface of the second mold is an end surface of the second mold on an upstream side with respect to the extrusion direction, wherein the honeycomb structure forming tool has a gap portion between an outer peripheral surface of the convex portion of the first mold and an inner peripheral surface of the annular second mold for extruding the kneaded material into a ring shape, and a groove portion having a plurality of grooves formed in the abutting surface of the first mold and / or in the abutting surface of the second mold, in which the movement of the kneading material is carried out between the first kneading material introduction hole and the second kneading material introduction hole, wherein the abutting surfaces of the first mold and the second mold are in contact with each other except for a region in which the groove region is formed.

[0014] [2] The honeycomb structure forming tool according to the above item [1], wherein a shape of the first slits is different from a shape of the second slits.

[0015] [3] The honeycomb structure forming tool according to the above items [1] or [2], wherein the groove portion is formed in the second shape.

[0016] [4] The honeycomb structure forming tool according to any one of the above items [1] to [3], wherein the width of the groove portion is from 0.1 to 1.5 mm.

[0017] [5] The honeycomb structure forming tool according to any one of the above items [1] to [4], wherein a depth of the grooves of the groove portion is from 0.1 to 5.0 mm.

[0018] [6] The honeycomb structure forming tool according to any one of the above items [1] to [5], wherein a ratio of a total area of ​​the groove portion and the open ends of the second wrought material introduction holes to an area of ​​a portion in which the groove portion is formed in the abutting surface of the second mold is in the range of 40 to 90%.

[0019] [7] The honeycomb structure forming tool according to any one of the above items [1] to [6], wherein a ratio of an area of ​​the central region of the first mold to an area of ​​an end face of a honeycomb molded body to be extruded is 30 to 70%.

[0020] [8] The honeycomb structure forming tool according to any one of the above items [1] to [7], wherein honeycomb surrounding slits extend from the first slits and honeycomb surrounding slits extend from the second slits in mutually crossing directions.

[0021] [9] The honeycomb structure forming die according to any one of the above items [1] to [8], wherein an arrangement direction of a honeycomb structure of the honeycomb formed body to be extruded through the first slits and an arrangement direction of a honeycomb structure of the honeycomb formed body to be extruded through the second slits are in directions crossing each other.

[0022]

[10] The honeycomb structure forming tool according to any one of the above items [1] to [9], wherein in the first mold, the central region is equal to the peripheral region with respect to an opening diameter of the first wrought material introduction hole and an interval between the first wrought material introduction holes.

[0023]

[11] The honeycomb structure forming tool according to any one of the above items [1] to

[10] , wherein the honeycomb structure forming tool has two or more second molds, wherein the second mold is replaced, whereby a depth of the grooves in the groove region is changeable.

[0024]

[12] The honeycomb structure forming tool according to any one of the above items [1] to

[11] , wherein the honeycomb structure forming tool has two or more first molds, wherein the first mold is replaced, whereby a depth of the grooves in the groove region is changeable.

[0025] A honeycomb structure forming die according to the present invention includes a first die in which a central portion on the side of a wrought material discharge surface has a convex portion protruding toward a downstream side in an extrusion direction of a wrought material, and an annular second die having a shape complementary to the convex portion of the first die. Furthermore, the honeycomb structure forming die according to the present invention has a groove portion in which the movement of the wrought material is performed between each first wrought material introduction hole and each second wrought material introduction hole, in abutting surfaces of the first die and the second die.

[0026] The honeycomb structure forming die according to the present invention is capable of forming a honeycomb formed body having a central portion different from a peripheral portion in terms of honeycomb structure with high quality. In other words, even when the positions of the first kneaded material introduction holes of the first die do not coincide with the positions of the second kneaded material introduction holes of the second die, a flow rate distribution of the kneaded material to be introduced into the second kneaded material introduction holes can be uniformed by the groove portion formed in the abutting surfaces of the first die and the second die. Therefore, the honeycomb structure forming die according to the present invention is capable of uniformizing an amount of the kneaded material ejected from the second slits of the second die and forming the honeycomb formed body with high quality.

[0027] Furthermore, according to the honeycomb structure forming die of the present invention, even if a back pressure is generated in the die upon exchanging the die or upon stopping the plunger extrusion, it is possible to effectively prevent the deformation of the second die. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view schematically illustrating a kneaded material discharge surface side of an embodiment of a honeycomb structure forming die according to the present invention; Fig. 2 is a plan view of the side of a wrought material introduction surface of the Fig. 1 shown honeycomb structure forming tool; Fig. 3 is a plan view of the side of a kneading material exit surface of a first mold, which Fig. 1 shown honeycomb structure forming tool; Fig. 4 is a plan view of the side of a wrought material exit surface of a second mold, showing the Fig.1 shown honeycomb structure forming tool; Fig. 5 is a plan view of the side of a wrought material introduction surface of the second mold, showing the Fig. 1 shown honeycomb structure forming tool; Fig. 6 is a cross-sectional view showing a cross section along the line AA' of the Fig. 1 schematically shows the honeycomb structure forming tool shown; Fig. 7 is an enlarged cross-sectional view of an enlarged part of Fig. 6; Fig. 8 is a perspective view schematically illustrating an example of a honeycomb structure manufactured with the honeycomb structure forming die according to the present invention; Fig. 9 is a plan view showing an inlet end face of the Fig. 8 schematically shows the honeycomb structure shown; Fig. 10 is a cross-sectional view showing a cross section along the line BB' in Fig.9 schematically; Fig. 11 is a plan view schematically illustrating a kneaded material discharge surface side of another embodiment of the honeycomb structure forming die according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Embodiments of the present invention will be described in more detail below with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and that design changes, improvements, and the like may be appropriately added based on common knowledge without departing from the spirit of the present invention. (1) Honeycomb structure forming tool:

[0029] An embodiment of a honeycomb structure forming tool according to the present invention will be described. Here, Fig.1 is a plan view schematically illustrating a kneaded material discharge surface side of one embodiment of the honeycomb structure forming die according to the present invention. Fig. 2 is a plan view of the side of a wrought material introduction surface of the Fig. 1 shown honeycomb structure forming tool. Fig. 3 is a plan view of the side of a kneading material exit surface of a first mold, which Fig. 1 shown honeycomb structure forming tool. Fig. 4 is a plan view of the side of a wrought material exit surface of a second mold, showing the Fig. 1 shown honeycomb structure forming tool. Fig. 5 is a plan view of the side of a wrought material introduction surface of the second mold, showing the Fig. 1 shown honeycomb structure forming tool. Fig. 6 is a cross-sectional view showing a cross section along the line AA' of the Fig.1 shows a schematic representation of the honeycomb structure forming tool. Fig. 7 is an enlarged cross-sectional view of an enlarged part of Fig. 6. It should be noted that in Fig. 3 and Fig. 5 The abutting surfaces of the first form and the second form are each shown hatched.

[0030] As in the Fig.As shown in FIGS. 1 to 7, a honeycomb structure forming die 100 according to the present invention includes a first die 10 and a second die 20. The first die 10 is disposed on an upstream side in an extrusion direction X of a wrought material of a molding raw material, and a central portion on the side of a wrought material discharge surface 18 has a convex portion 16 protruding toward a downstream side in the extrusion direction. The second die 20 is an annular die disposed on the downstream side of the first die 10 and having a shape complementary to the convex portion 16 of the first die 10. Hereinafter, the honeycomb structure forming die 100 according to the present embodiment will occasionally be referred to simply as the "forming die 100."The extrusion direction X of the wrought material is an extrusion direction when performing extrusion using the die 100 according to the present embodiment, and the direction extends from a wrought material introduction surface 19 to the wrought material exit surface 18.

[0031] According to the molding die 100 of the present embodiment, first molded material introduction holes 12 and first mesh slots 11 communicating with the first molded material introduction holes 12 are formed in the central region 15 of the first mold 10. The first molded material introduction holes 12 are formed coaxially with intersections of the first mesh slots 11 in the extrusion direction X. In other words, the first molded material introduction holes 12 communicate with the intersections of the first mesh slots 11. In the peripheral region 17 surrounding the central region 15 of the first mold 10, the first molded material introduction holes 12 are formed to pass through the peripheral region 17 of the first mold 10.

[0032] The annular second mold 20 is formed with second molding material introduction holes 22, into which the molding material emerging from the first molding material introduction holes 12 formed in the peripheral region 17 of the first mold 10 is introduced, and with second mesh slots 21 communicating with the second molding material introduction holes 22. The second molding material introduction holes 22 are formed coaxially with intersection points of the second mesh slots 21 in the extrusion direction X. In other words, the second kneaded material introduction holes 22 communicate with the intersection points of the second lattice slots 21. The molding tool 100 according to the present embodiment is further formed such that the positions of the openings of the first kneaded material introduction holes 12 of the peripheral portion 17 of the first mold do not coincide with the positions of the openings of the second kneaded material introduction holes 22 of the second mold 20 in at least a part of the molding tool.

[0033] In the molding die 100 according to the present embodiment, the first die 10 and the second die 20 are combined into one piece, so that an end surface of the peripheral portion 17 of the first die 10 on the downstream side in the extrusion direction X abuts against an end surface of the annular second die 20 on the upstream side in the extrusion direction X. Hereinafter, the end surface of the peripheral portion 17 of the first die 10 on the downstream side in the extrusion direction X is sometimes referred to as an "abutting surface 14 of the first die 10," and the end surface of the annular second die 20 on the upstream side in the extrusion direction X is sometimes referred to as an "abutting surface 24 of the second die."Further, when simply mentioning the upstream side, it means the upstream side in the extrusion direction X, and when simply mentioning the downstream side, it means the downstream side in the extrusion direction X.

[0034] The molding tool 100 according to the present invention has a groove portion 31, in which the movement of the kneaded material occurs between the first kneaded material introduction hole 12 and the second kneaded material introduction hole 22, in the abutting surfaces 14 and 24 of the first mold 10 and the second mold 20.

[0035] The molding die according to the present embodiment has a gap portion 35 between an outer peripheral surface of the convex portion 16 of the first die 10 and an inner peripheral surface of the annular second die 20 to extrude the kneaded material into a ring shape. In other words, in the molding die 100 according to the present embodiment, a cavity portion 26 is formed in a central portion 25 of the second die 20 to be slightly larger than a peripheral edge of the convex portion 16 of the first die 10. According to this structure, when the first die is combined with the second die with the convex portion 16 of the first die 10 inserted into the cavity portion 26 of the annular second die 20, the annular gap portion 35 is formed between the convex portion 16 of the first die 10 and the second die 20.The annular gap portion 35 functions as a gap portion 35 for forming a boundary wall of a honeycomb molded body. In the present invention, "the annular second mold having a shape complementary to the convex portion 16 of the first mold 10" means an annular mold having the cavity portion 26 that has the same shape as the convex portion 16 of the first mold 10 or that is slightly larger than the convex portion 16 of the first mold 10.

[0036] In the molding die 100 according to the present embodiment, an end surface of the first die 10 on the upstream side in the extrusion direction X is the kneaded material introduction surface 19 of the entire molding die 100. Therefore, during extrusion, the kneaded material of the molding raw material is initially introduced into the first kneaded material introduction holes 12 opened in the kneaded material introduction surface 19 of the first die 10. The kneaded material introduced into the first kneaded material introduction holes 12 of the central portion 15 of the first die 10 moves to the first mesh slits 11 communicating with the first kneaded material introduction holes 12 and is ejected from the kneaded material discharge surface 18 of the first die as a molded body corresponding to a shape of the first slits 11.On the other hand, the wrought material introduced into the first wrought material introduction holes 12 of the peripheral portion 17 of the first die 10 is ejected on one side of the abutting surface 14 of the first die 10 and introduced into the second wrought material introduction holes 22 of the second die 20 through the groove portion 31. In this case, even if the positions of the first wrought material introduction holes 12 of the first die 10 do not coincide with those of the second wrought material introduction holes 22 of the second die 20, the flow rate distribution of the wrought material can be uniformed by the groove portion 31 formed in the abutting surfaces 14 and 24 of the first die 10 and the second die 20.The kneaded material introduced into the second kneaded material introduction holes 22 of the second mold 20 moves to the second mesh slots 21 communicating with the second kneaded material introduction holes 22 and is ejected from the kneaded material discharge surface 28 of the second mold as a molded body corresponding to a shape of the second slots 21. Therefore, the molding die 100 according to the present embodiment is capable of uniformizing the amount of kneaded material ejected from the second slots 21 of the second mold 20 and molding the honeycomb molded body with high quality. Furthermore, the groove portion 31 is also connected to the gap portion 35 to extrude the wrought material in the ring shape, and thus the wrought material introduced into the first wrought material introduction holes 12 of the peripheral portion 17 of the first die 10 is also introduced into the gap portion 35 through the groove portion 31.This makes it possible to make the flow rate distribution of the kneading material to be introduced into the gap region 35 more uniform, and it is also possible to particularly effectively prevent the generation of molding defects around the boundary wall of the honeycomb molded article to be extruded. Consequently, the molding die 100 according to the present embodiment is particularly capable of molding a honeycomb molded article having a central portion different from a peripheral portion in terms of honeycomb structure with high quality.

[0037] In this specification, the "honeycomb structure" refers to a honeycomb structure aligned according to a partition wall thickness, a honeycomb density, and a honeycomb shape. Furthermore, the "slit shape" refers to the shape of the slots aligned according to a width, a depth, and a length of each slot formed in the mold and a configuration of the interconnection of the slots.

[0038] Furthermore, the abutting surfaces 14 and 24 of the first die 10 and the second die 20 are in contact with each other except for a portion where the groove portion 31 is formed, and thus, it is possible to effectively prevent deformation of the second die 20. For example, when the end surface of the peripheral portion 17 of the first die 10 on the downstream side does not abut against the end surface of the second die 20 on the upstream side and the second die 20 is in a state similar to a one-sided suspension, the second die may be deformed due to the generation of back pressure in the die 100 at the time of replacement or when the piston extrusion is interrupted.

[0039] Furthermore, in the molding die 100 according to the present embodiment, even when the honeycomb molded body has a boundary wall at a boundary between the central region and the peripheral region, the supply of the kneading material for molding the boundary wall can be sufficiently ensured through the groove portion 31. Consequently, the molding die 100 according to the present embodiment is capable of effectively preventing the generation of molding defects in the boundary wall and its surroundings in the honeycomb molded body.

[0040] Furthermore, although not shown in the drawings, in the molding die of the present embodiment, a plurality of types of second molds different in the shape of the second slits can be separately manufactured, and the second mold is interchangeable for use in accordance with the honeycomb structure of the honeycomb molded article to be molded. The second molded material introduction holes of the second mold are formed coaxially with the intersection points of the second mesh slits in the extrusion direction, and thus the respective opening positions of the second molded material introduction holes in the abutment surface vary in accordance with the shape of the second slits of the second mold.The mold according to the present embodiment has the groove portion in the mutual abutting surfaces, and thus, even when the second mold having a different shape of the second slits is used, uniform extrusion can always be achieved in the central portion and the peripheral portion without affecting the movement of the kneading material in the mold.

[0041] Here, the honeycomb structure manufactured by the honeycomb structure forming die according to the present embodiment will be described. Fig. 8 is a perspective view schematically illustrating an example of a honeycomb structure manufactured with the honeycomb structure forming die according to the present invention. Fig. 9 is a plan view showing an inlet end face of the Fig. 8 schematically shows the honeycomb structure. Fig. 10 is a cross-sectional view showing a cross section along the line BB' in Fig.9 shows schematically.

[0042] One in Fig. 8 to Fig. The honeycomb structure 200 shown in Figure 10 comprises a columnar honeycomb structural body 204 with porous partition walls 201 and a peripheral wall 203 arranged around a periphery of the partition walls 201. The partition walls 201 of the honeycomb structural body 204 form a plurality of honeycombs 202 that extend from an inlet end face 211 to an outlet end face 212 and become passageways for a fluid. Furthermore, the honeycomb structural body 204 has a central honeycomb structure 215, a peripheral honeycomb structure 216, and a boundary wall 208 arranged in a boundary region between the peripheral honeycomb structure 216 and the central honeycomb structure 215. In the honeycomb structure body 204, the central honeycomb structure 215 and the peripheral honeycomb structure 216 are different honeycomb structures.

[0043] Here, the central honeycomb structure 215 is a honeycomb structure formed by a plurality of honeycombs 202a formed in a central part of the honeycomb structural body 204 in a plane of the honeycomb structural body 204 that is perpendicular to an extending direction of the honeycombs 202. The peripheral honeycomb structure 216 is a honeycomb structure formed by a plurality of honeycombs 202b formed closer to a periphery of the honeycomb structural body 204 than to a central part of the honeycomb structural body 204 in the plane described above.

[0044] The "honeycomb structure" is a structure formed by a group of repeating units, and one repeating unit corresponds to one honeycomb 202 formed by the partition walls 201, or to a combination of a plurality of honeycombs 202 in the plane perpendicular to the extending direction of the honeycombs 202. For example, when the honeycombs having the same shape are regularly arranged in the above-mentioned plane, a region where honeycombs having the same shape exist becomes a honeycomb structure. Further, when a combination of a plurality of honeycombs having different honeycomb shapes forms a repeating unit, a region where the repeating unit exists forms a honeycomb structure.

[0045] When two honeycomb structures are described as "different honeycomb structures," this means that when comparing the two honeycomb structures, the structures differ in either the partition thickness, the honeycomb density, or the honeycomb shape. Here, when "the structures differ in partition thickness," this means that when comparing the partition thicknesses of the two honeycomb structures, there is a difference of 25 µm or more. Furthermore, when "the structures differ in honeycomb density," this means that when comparing the honeycomb densities of two honeycomb structures, there is a difference of 7 honeycombs / cm. 2 or more.

[0046] The molding tool according to the present embodiment can be suitably used for molding a honeycomb molded body for producing the Fig.8 to 10. A more suitable configuration of the molding tool according to the present embodiment will be described below.

[0047] In the molding tool according to the present embodiment, it is preferable that the shape of the first slots 11 is different from the shape of the second slots 21, as shown in the Fig. 1 to 7. There are no particular restrictions on the shape of the first slits 11 and the shape of the second slits 21, and the shapes can be appropriately selected in accordance with the honeycomb structure of the honeycomb molded body to be formed.

[0048] The groove portion 31 formed in the abutting surfaces 14 and 24 of the first die 10 and the second die 20 can be formed on the first die 10 or the second die 20 side. In the die 100 according to the present embodiment, it is preferable that the groove portion 31 be formed on the second die 20 side. When the groove portion 31 is formed on the second die 20 side, the strength of the die 100 is preferably maintained, and the die is preferably easy to manufacture. For example, the groove portion 31 is formed on the second die 20 side, whereby even if the stress to be applied to the groove portion 31 becomes a stress in a compression direction and a concentration of the stress occurs in the groove portion 31, it is possible to achieve the strength of the die 100.

[0049] The width of the groove portion 31 is not particularly limited, but the width is preferably from 0.1 to 1.5 mm, and more preferably from 0.3 to 0.7 mm. If the width of the groove portion 31 is less than 0.1 mm, extrusion resistance during extrusion disadvantageously increases. On the other hand, if the width of the groove portion 31 is greater than 1.5 mm, a contact area of ​​the first die with the second die disadvantageously becomes excessively small, and flowability disadvantageously varies due to deformation of a butt portion.

[0050] The depth of the grooves of the groove portion 31 in the extrusion direction X is not particularly limited, but the depth is preferably from 0.1 to 5.0 mm, and more preferably from 0.3 to 1.2 mm. If the depth of the groove portion 31 is less than 0.1 mm, extrusion resistance during extrusion disadvantageously increases. On the other hand, if the depth of the groove portion 31 is greater than 5.0 mm, the substantial thickness of the second mold disadvantageously decreases, and the strength of the entire mold is disadvantageously deteriorated.

[0051] A ratio of a total area of ​​the groove portion 31 and the open ends of the second wrought material introduction holes 22 in a portion 32 to an area in the portion in which the groove portion 31 is formed in the abutting surface 24 of the second die 20 is preferably from 40 to 90%, and more preferably from 50 to 80%. Here, the “portion in which the groove portion 31 is formed in the abutting surface 24 of the second die 20” means an area surrounded by lines connecting terminal ends of the respective grooves of the groove portion 31 in the abutting surface 24 of the second die. Fig.In FIG. 5, a region surrounded by a dashed line denoted by reference numeral 32 is the "region 32 in which the groove portion 31 is formed." Therefore, the area of ​​the region 32 in which the groove portion 31 is formed as described above includes the surfaces of the groove portion 31 and the open ends of the second kneaded material introduction holes 22 in this region. If the above ratio is less than 40%, the extrusion resistance during extrusion disadvantageously increases. On the other hand, if the ratio exceeds 90%, the contact area of ​​the first die with the second die disadvantageously becomes excessively small, and the flowability disadvantageously varies due to the deformation of a butt portion.

[0052] The shape of the groove portion 31 in the abutting surface 24 of the second mold 20 is not particularly limited. For example, it is preferable that the shape be a lattice shape to connect two closely spaced open ends of the open ends of the second kneaded material introduction holes 22 in the abutting surface 24 of the second mold 20 by a straight line. Such a structure can minimize the deterioration of the strength of the molding die 100. Note that the structure may further include the groove portion 31 having a shape such that the open end of one second kneaded material introduction hole 22 is connected to the open end of the second kneaded material introduction hole 22 provided at a position remote from the second kneaded material introduction hole 22 that is close to the one second kneaded material introduction hole.

[0053] The molding tool according to the present embodiment may have two or more second molds 20 if the groove portion 31 is formed in the abutment surface 24 of the second mold 20, as shown in FIGS. Fig. 1 to 7. In the respective second molds 20, the depth of the groove portion formed in the abutment surface 24 varies, and thus, when the second mold 20 is replaced, the depth of the grooves of the groove portion 31 is variable. For example, the second mold in which the depth of the grooves of the groove portion 31 is optimal can be appropriately selected for use from the two or more second molds 20 according to the molding conditions during extrusion.

[0054] Furthermore, although not shown in the drawings, the molding die may have two or more first molds if the groove portion is formed in the abutment surface of the first mold. In each of the first molds, the depth of the groove portion formed in the abutment surface varies, and thus, when the first mold is replaced, the depth of the grooves of the groove portion is variable. For example, the first mold in which the depth of the grooves of the groove portion is optimal can be appropriately selected for use from the two or more first molds according to the molding conditions during extrusion.

[0055] A ratio of an area of ​​the central region 15 of the first mold 10 to an area of ​​an end face of the honeycomb molded body to be extruded can be appropriately determined in accordance with the honeycomb structures of the central part and the peripheral part of the honeycomb molded body to be molded (see, for example, Fig.8 to Fig. 10). It should be noted that in the mold according to the present embodiment, the above ratio is preferably from 30 to 70%, and more preferably from 40 to 60%.

[0056] As described above, in the molding die 100, the cavity portion 26 in the central portion 25 of the second mold 20 is formed to be slightly larger than the peripheral edge of the convex portion 16 of the first mold 10, and the annular gap portion 35 is formed between the convex portion 16 of the first mold 10 and the second mold 20. There is no particular limitation on a distance between the above-mentioned annular gap portions 35, and the distance can be appropriately selected in accordance with a thickness of the boundary wall of the honeycomb formed body to be formed. For example, it is preferable that the distance between the annular gap portions 35 is from 0.04 to 0.50 mm.

[0057] In the first mold 10, it is preferable that the central region 15 be equal to the peripheral region 17 in terms of the opening diameter of the first kneaded material introduction hole 12 and a distance between the first kneaded material introduction holes 12. According to such a structure, for example, it is possible to easily manufacture the first mold 10 at low cost.

[0058] Furthermore, in the molding tool according to the present embodiment, honeycomb-enclosing slits from the first slits and honeycomb-enclosing slits from the second slits may extend in mutually intersecting directions. Here, the "honeycomb" means a space defined by partition walls in the honeycomb molded body to be molded. For example, a Fig. 11 is manufactured in a state in which the first slots 11 of the first mold are 10 to 45° from the Fig.1 are rotated clockwise. Consequently, in the mold 300, honeycomb surrounding slits among the first slits 11 and honeycomb surrounding slits among the second slits 21 do not have a parallel positional relationship. In the mold of the present embodiment, even when the respective honeycomb surrounding slits intersect at the first slits and the second slits as described above, it is possible to uniform the flow rate distribution of the kneaded material. Therefore, it is possible to uniform the amount of kneaded material ejected from the second slits of the second mold, and it is possible to mold the honeycomb molded article with high quality.

[0059] In the mold 100 of the present embodiment, as shown in Fig.1, an arrangement direction of the honeycomb structure of the honeycomb molded body to be extruded through the first slits 11 is parallel to an arrangement direction of the honeycomb structure of the honeycomb molded body to be extruded through the second slits 21. In other words, an extending direction of the first slits 11 of the first mold 10 is parallel to an extending direction of the second slits 21 of the second mold 20. As shown in the Fig. However, in the molding tool 300 shown in Fig. 11, the arrangement direction of the honeycomb structure of the honeycomb molded body to be extruded through the first slits 11 and the arrangement direction of the honeycomb structure of the honeycomb molded body to be extruded through the second slits 21 may be in mutually intersecting directions. Fig. 11 is a plan view schematically illustrating the side of a kneaded material discharge surface of another embodiment of the honeycomb structure forming die according to the present invention. Fig. 11 are components which are similar to those of the mold shown in Fig. 1 are similar, are designated by the same reference numerals and their description is occasionally omitted.

[0060] The Fig. The mold 300 shown in Figure 11 also has a groove area 31 (see Fig. 7), in which the movement of the wrought material between a first wrought material introduction hole 12 and a second wrought material introduction hole 22 in the abutting surfaces 14 and 24 of a first mold 10 and a second mold 20 (see Fig. 7). Consequently, even if, as in the Fig.11, an extending direction of the first slits 11 of the first mold 10 and an extending direction of the second slits 21 of the second mold 20 intersect each other, making it possible to uniformly distribute the flow rate of the kneaded material. Therefore, it is possible to uniformly distribute the amount of kneaded material ejected from the second slits 21 of the second mold 20, and it is possible to mold the honeycomb molded body with high quality.

[0061] The Fig. The mold 300 shown in Figure 11 is prepared in advance so that the first slots 11 of the first mold 10 are rotated clockwise by 45°. Fig. However, the mold 100 shown in Figure 1 can be used by rotating the first mold 10 clockwise to 45°. Even if the first mold 10 of the Fig.1 is rotated 100 to 45° clockwise, the groove area 31 is present in the abutment surfaces 14 and 24 of the first mold 10 and the second mold 20, as shown in the Fig. 6 and Fig. 7, and thus the movement of the kneaded material in the mold 100 is not obstructed. A conventional mold that does not include the groove portion is designed such that, for example, the first kneaded material introduction holes of the first die align with the second kneaded material introduction holes of the second die in the extrusion direction of the kneaded material. Therefore, if only the first die is rotated during operation, the movement of the kneaded material in the die may be obstructed.

[0062] In the Fig. 1 to Fig.7, there are no particular restrictions on the thickness of the first mold 10, a protrusion height of the convex portion 16 of the first mold 10, and a thickness of the second mold 20. It is preferable that the thickness of the first mold 10 is from 10 to 50 mm. It is preferable that the protrusion height of the convex portion 16 of the first mold 10 is from 10 to 30 mm. It is preferable that the thickness of the second mold 20 is from 10 to 30 mm. Note that the protrusion height of the convex portion 16 of the first mold 10 may be the same as or different from the thickness of the second mold 20.For example, when the convex portion 16 of the first mold 10 is inserted into the cavity portion 26 of the annular second mold 20, a position of the wrought material exit surface 18 of the first mold 10 may coincide with a position of the wrought material exit surface 28 of the second mold 20, but need not coincide therewith.

[0063] An example of a material of a first mold substrate 13 constituting the first mold 10 and a second mold substrate 23 constituting the second mold 20 is a metal or an alloy commonly used as a material of a honeycomb structure mold. Hereinafter, the first mold substrate and the second mold substrate are generally referred to simply as the "mold substrate" on occasion. An example of the material of the mold substrate is a metal or an alloy containing at least one metal selected from the group consisting of iron (Fe), titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al).

[0064] An example of an alloy used as a mold substrate material is a stainless alloy, specifically SUS630. This stainless alloy is an inexpensive material that is relatively easy to process. Another example of an alloy used as a mold substrate is a tungsten carbide-based cemented carbide, which has excellent wear resistance. By using a mold substrate made of a tungsten carbide-based cemented carbide or the like, it is possible to produce a honeycomb mold in which the slots are subject to less wear.

[0065] There is no particular limitation on the method for manufacturing the mold of the present embodiment. For example, the mold according to the present embodiment can be manufactured according to a conventional mold manufacturing method.

[0066] The first wrought material introduction holes and the second wrought material introduction holes can be formed using known machining methods such as drilling machining, discharge machining, electrolytic machining or laser machining of the first mold substrate and the second mold substrate.

[0067] The first slots and the second slots may be formed using known machining methods such as grinding machining, discharge machining, electrolytic machining, or laser machining of the first mold substrate and the second mold substrate.

[0068] The groove portion of the abutting surfaces of the first mold and the second mold can be formed using known machining methods such as grinding, discharge machining, electrolytic machining, or laser machining.

[0069] The convex area forming the central area of ​​the first shape can be formed by grinding, discharge machining or joining two elements. Examples

[0070] Hereinafter, the present invention will be described in further detail with reference to examples, but the present invention is not limited by these examples. Example 1

[0071] In Example 1, a mold for producing a honeycomb structure 200 having a honeycomb structure in which a central honeycomb structure 215 of a honeycomb structural body 204 is different from a peripheral honeycomb structure 216 was prepared as shown in Fig. 8 to Fig.10. More specifically, in Example 1, the mold was manufactured so that the honeycomb structure of the final product was constructed as follows. The honeycomb structure of the final product had a round column shape, in which the diameter of each end face was 100 mm, and the diameter of the central honeycomb structure in the end face was 70 mm. The honeycomb structure had a boundary wall with a thickness of 0.1 mm at the boundary between the central honeycomb structure and the peripheral honeycomb structure. In the central honeycomb structure, the honeycomb shape was quadrangular, the thickness of the partition wall was 0.09 mm, and the honeycomb density was 93 honeycombs / cm. 2 . In the circumferential honeycomb structure, the honeycomb shape was square, the thickness of the partition wall was 0.11 mm and a honeycomb density was 62 honeycombs / cm 2 . It should be noted that the respective dimensions of the honeycomb structure described above do not include any manufacturing tolerances.

[0072] First, in Example 1, a plate-shaped first molding substrate with a vertical dimension of 200 mm, a lateral dimension of 200 mm, and a thickness of 20 mm was prepared. A surface of the prepared first molding substrate was defined as a wrought material discharge surface, and a convex portion was formed by discharge machining such that the projection length was 10 mm.

[0073] Subsequently, first mesh slits were formed in the molded material exit surface of the convex portion of the first molding substrate. The first mesh slits were formed in a slit shape to extrude the partition walls that form the central honeycomb structure of the aforementioned honeycomb structure of the final product. The first slits were formed by grinding.

[0074] Next, first molded material introduction holes with an opening diameter of 1.2 mm were formed in a molded material introduction surface of the first molding substrate so as to communicate with the intersection points of the first slits. Also, in a peripheral region of the first molding substrate that did not have a convex portion, first molded material introduction holes were formed with the same pitch as in a central region having the convex portion. The first molded material introduction holes of the peripheral region of the first molding substrate were through holes extending from a molded material introduction surface of the first molding substrate to a butt surface with a second mold mentioned below. As described above, a first mold was manufactured in the mold of Example 1.

[0075] Subsequently, a plate-shaped second mold substrate with a vertical dimension of 200 mm, a lateral dimension of 200 mm, and a thickness of 10 mm was prepared. The mold substrate was made of stainless steel. A central region of the prepared second mold substrate was cut out in a circular shape, thus forming the second mold substrate with a ring shape.

[0076] Subsequently, second mesh slits were formed in the molded material exit surface of a convex portion of the second mold substrate. The second mesh slits were formed in a slit shape to extrude the partition walls that form the peripheral honeycomb structure of the aforementioned honeycomb structure of the final product. The second slits were formed by grinding.

[0077] Subsequently, second molded material introduction holes with an opening diameter of 1.2 mm were formed on the surface of the second mold substrate opposite the molded material exit surface, communicating with the intersection points of the second slits. When the second mold substrate is combined with the first mold substrate, the surface of the second mold substrate opposite the molded material exit surface becomes the abutting surface that comes into contact with the peripheral portion of the first mold substrate.

[0078] Subsequently, a groove portion was formed in the above-mentioned abutting surface of the second mold substrate, in which the movement of the molded material between the first molded material introduction hole and the second molded material introduction hole was performed. This groove portion had a lattice shape such that two closely spaced open ends of the second molded material introduction holes were connected by a straight line. A width of the groove portion was set to 0.5 mm, and a depth of the groove portion in an extrusion direction was set to 0.5 mm. The groove portion was formed by grinding. As described above, the second mold was manufactured in the mold of Example 1.

[0079] Then, the second mold was combined with the first mold, and the convex portion of the center portion of the first mold was inserted into the cavity portion of the center portion of the second mold, thus manufacturing the molding die according to Example 1. A ratio of an area of ​​open ends of the groove portion in one region to an area of ​​the region in which the groove portion was formed in the abutment surface of the second mold was 71%. Hereinafter, the area of ​​the open ends of the aforementioned groove portion is occasionally referred to as a "groove portion area ratio." Table 1 shows a "mold configuration," "presence of the groove portion," a "width (mm) of the groove portion," a "depth (mm) of the groove portion," and the "area ratio (%) of the groove portion."It should be noted that the table shows a mold as a "two-piece structure" in a "Mold Structure" column when the mold is manufactured by combining the first mold and the second mold into one mold like the mold of Example 1. On the other hand, the table shows the mold as a "one-piece structure" in the "Mold Structure" column when the mold is manufactured by manufacturing a single mold substrate such that a central portion differs from a peripheral portion in the shape of the slits.

[0080] The total operating time required to manufacture the mold according to Example 1 was 70 hours. Molded body quality, extrusion resistance, and occurrence of second-die deformation were evaluated using the mold according to Example 1 by the methods described below. Table 1 shows the results. Molded body quality

[0081] A honeycomb structure formed from a cordierite composition was extruded using the manufactured mold. The extruded honeycomb structure was visually inspected, and the quality of the honeycomb structure was evaluated according to the following evaluation standards. If there are no defects in the appearance, a molded article is rated as "good." If there is a defect in the appearance or molding cannot be performed, the molded article is rated as "rejected." Here, the "defect in the appearance" means that the partition walls constituting the honeycomb structure are bent due to deviations in the extrusion speed in the respective areas of the mold. Extrusion resistance

[0082] A pressure sensor was placed on the upstream side of the manufactured die, and a honeycomb structure made of a cordierite composition was extruded using the die with the pressure sensor. The pressure on the upstream side of the die during extrusion was measured with the pressure sensor, and the measured pressure was obtained as an extrusion resistance of the die under evaluation. The extrusion resistance during extrusion was evaluated according to the following evaluation standards. A pressure range during the production of an ordinary honeycomb product is defined as a "standard," an extrusion resistance higher than the "standard" is evaluated as a "large" extrusion resistance, and an extrusion resistance smaller than the "standard" is evaluated as a "small" extrusion resistance. Presence of a deformation of the second form

[0083] Using the manufactured mold, extrusion was performed three times under the same conditions as in the molded article quality evaluation. In the state after extrusion, the presence of deformation of the second mold was confirmed by visual inspection. If deformation is confirmed in the second mold, the table displays "Present" in the corresponding column. If no deformation of the second mold could be confirmed, the table displays "No" in the corresponding column. [Table 1] Mold construction Presence of the groove area Width of the groove area (mm) Depth of the groove area (mm) Area ratio of the groove area (%) Total operating time required for production (hours) Extrusion resistance Molded body quality Presence of a deformation of the second form Example 1 Two-part structure Yes 0,5 0,5 71 70 standard Good No Example 2 Two-part structure Yes 0,5 0,7 76 70 small Good No Example 3 Two-part structure Yes 0,7 1 80 70 small Good No Example 4 Two-part structure Yes 0,5 0,3 71 70 large Good No Comparison example 1 One-piece construction - - - - 100 small Committee No Comparison example 2 Two-part structure No - - - 60 large Committee No Comparison example 3 Two-part structure No (entire impact surface is a cavity) - - - 70 small good (assuming that the quality changes with the deformation Yes ngworsened) Examples 2 to 4

[0084] The procedure of Example 1 was repeated except that a "width (mm) of the groove portion," a "depth (mm) of the groove portion," and a "area ratio (%) of the groove portion" were changed to the values ​​shown in Table 1 to prepare the molds. The procedure of Example 1 was repeated to conduct evaluations of "molded article quality," "extrusion resistance," and "presence of second-shape deformation" using the molds according to Examples 2 and 4. Table 1 shows the results. Comparison example 1

[0085] In Comparative Example 1, a plate-shaped molding substrate having a vertical dimension of 200 mm, a lateral dimension of 200 mm, and a thickness of 20 mm was prepared. The molding substrate was made of stainless steel. A surface of the prepared molding substrate was defined as a wrought material discharge surface, and slits having the same shape as the first slits in Example 1 were formed in a central region on the wrought material discharge surface side. Subsequently, slits having the same shape as the second slits of the molding die of Example 1 were formed in a peripheral region on the wrought material discharge surface side of the molding substrate. Then, an annular slit was formed at a position corresponding to a gap region of Example 1 to connect one end of each first slit to one end of each second slit.Subsequently, molding material introduction holes with an opening diameter of 1.2 mm were formed from the molding material introduction surface side of the molding substrate so that they communicated with the intersection points of the respective slits. As described above, a mold according to Comparative Example 1 was manufactured.

[0086] The total operating time required to manufacture the mold according to Comparative Example 1 was 100 hours. The procedure of Example 1 was repeated to conduct evaluations of the molded article quality, extrusion resistance, and presence of second-shape deformation using the mold according to Comparative Example 1. Table 1 shows the results. Comparison example 2

[0087] In Comparative Example 2, a first mold constructed in the same manner as the first mold of the molding die according to Example 1 was initially prepared. Subsequently, in Comparative Example 2, a second molding die was prepared without forming groove portions in an abutting surface of a second molding substrate as in the molding die of Example 1. The second molding die was combined with the first molding die, and a convex portion of a central portion of the first molding die was inserted into a cavity portion of a central portion of the second molding die, thus preparing a molding die according to Comparative Example 2.

[0088] The total operating time required to manufacture the mold according to Comparative Example 2 was 60 hours. The procedure of Example 1 was repeated to conduct evaluations of "molded article quality," "extrusion resistance," and "presence of second-shape deformation" using the mold according to Comparative Example 2. Table 1 shows the results. Comparison example 3

[0089] In Comparative Example 3, a first mold constructed in the same manner as the first mold of the molding die of Example 1 was initially prepared. Subsequently, in Comparative Example 3, a second mold was prepared in which a 0.5 mm portion was removed from an abutting surface of a second molding substrate in an extrusion direction by discharge machining without forming groove portions in the abutting surface of the second molding substrate as in the molding die of Example 1. The second mold was combined with the first mold, and a convex portion of a central portion of the first mold was inserted into a cavity portion of a central portion of the second mold, thus preparing a molding die of Comparative Example 3.In the mold of Comparative Example 3, an end face of a peripheral portion of the first mold on a downstream side did not abut against an end face of the second mold on an upstream side, and the second mold was combined with the first mold in a cantilevered state.

[0090] The total operating time required to manufacture the mold according to Comparative Example 3 was 70 hours. The procedure of Example 1 was repeated to conduct evaluations of "molded body quality," "extrusion resistance," and "presence of second-shape deformation" using the mold according to Comparative Example 3. Table 1 shows the results. Results

[0091] With the molds according to Examples 1 to 4, it was possible to shorten the production time, and the evaluations of the molded article quality were adequate compared to the mold according to Comparative Example 1. Even when evaluating the presence of deformation of the second mold, no deformation of the second mold was confirmed.

[0092] As a result, the molding die of Comparative Example 1 resulted in rejects during the evaluation of molded product quality. The reason for this result is presumably that when the central portion of the mold differs from its peripheral portion in terms of the shape of the slits, the flow rate distribution of the molded material in the molding die tends to become uneven, and the amount of molded material ejected from the slits is not uniform. Furthermore, when extrusion was performed using the molding die of Comparative Example 1, the demand for molded material for forming a boundary wall exceeded the supply, and a number of molding defects were confirmed in the boundary wall and its surroundings.

[0093] In the molding die according to Comparative Example 2, in an area where the positions of the first molding material introduction holes of the first mold did not match those of the second molding material introduction holes of the second mold, the movement of the molding material was hindered, and as a result, rejects were obtained in the molded article quality evaluation. Furthermore, when extrusion was performed using the molding die according to Comparative Example 2, the demand for molding the boundary wall exceeded the supply, and numerous molding defects were confirmed in the boundary wall and its surroundings.

[0094] For the mold according to Comparative Example 3, the evaluation of the molded article quality was adequate, but when evaluating the presence of deformation of the second mold, the deformation of the second mold was confirmed. If the second mold is significantly deformed, the molded article quality may be affected. Furthermore, if the second mold is easily deformed, there is a concern that the manufacturing cost of a product will increase due to mold replacement or the like.

[0095] A honeycomb structure forming die according to the present invention can be used to produce a honeycomb formed body having a central part different from a peripheral part in terms of the honeycomb structure. List of reference symbols 10 first form 11 first slot 12 first kneading material insertion hole 13 first mold substrate 14 Impact surface (the impact surface of the first form) 15 Middle area 16 convex area 17 Circumference range 18 Wrought material exit surface (the wrought material exit surface of the first mold) 19 Wrought material introduction surface 20 second form 21 second slot 22 second kneading material insertion hole 23 second mold substrate 24 Impact surface (the impact surface of the second form) 25 Middle range 26 Cavity area 27 Circumference area 28 Wrought material exit surface (the wrought material exit surface of the second mold) 31 Groove area 32 Area in which the groove area is formed 35 Gap area (a gap area to form a boundary wall) 100 and 300 honeycomb structure forming tool (the forming tool) 200 honeycomb structure 201 Partition wall 202 honeycomb 202a Honeycomb (combs of a central honeycomb structure) 202b Honeycomb (honeycombs of a circumferential honeycomb structure) 203 Perimeter wall 204 honeycomb structural bodies 208 boundary wall 211 Inlet face 212 Outlet face 215 central honeycomb structure 216 circumferential honeycomb structure X Extrusion direction

Claims

[1] Honeycomb structure forming tool (100, 300) comprising: a first mold (10) disposed on an upstream side in an extrusion direction (X) of a kneaded material of a molding raw material, and in which a central portion (15) on the side of a kneaded material discharge surface (18) has a convex portion (16) projecting toward a downstream side in the extrusion direction (X); and an annular second mold (20) arranged on the downstream side of the first mold (10) and having a shape complementary to the convex region (16), wherein first kneading material introduction holes (12) and first grid slots (11) communicating with the first kneading material introduction holes (12) are formed in the central region (15) of the first mold (10), in a peripheral region (17) surrounding the central region (15) of the first mold (10), the first kneading material introduction holes (12) are formed such that they extend through the peripheral region (17) of the first mold (10), second kneading material introduction holes (22) are formed in the annular second mold (20), into which the kneading material discharged from the first kneading material introduction holes (12) formed in the peripheral region (17) of the first mold (10) is introduced, and second grid slots (21) communicating with the second kneading material introduction holes (22), Positions of the opening of the first kneading material introduction holes (12) of the peripheral region (17) of the first mold (10) do not coincide with the positions of the openings of the second kneading material introduction holes (22) of the second mold (20) at least in a part of the honeycomb structure molding tool (100, 300), an abutment surface (14) of the first mold (10) is an end face of the peripheral region (17) of the first mold (10) on a downstream side with respect to the extrusion direction (X), and an abutment surface (24) of the second mold (20) is an end face of the second mold (20) on an upstream side with respect to the extrusion direction (X), and wherein the honeycomb structure forming tool (100, 300) comprises: a gap region (35) between an outer peripheral surface of the convex portion (16) of the first mold (10) and an inner peripheral surface of the annular second mold (20) for extruding the kneaded material into a ring shape, and a groove region (31) having a plurality of grooves formed in the abutting surface (14) of the first mold (10) and / or in the abutting surface (24) of the second mold (20), and in which the movement of the kneading material between the first kneading material introduction holes (12) and the second kneading material introduction holes (22) is carried out, wherein the abutting surfaces (14, 24) of the first mold (10) and the second mold (20) are in contact with each other except for a region in which the groove region (31) is formed. [2] The honeycomb structure forming tool (100, 300) according to claim 1, wherein a shape of the first lattice slots (11) is different from a shape of the second lattice slots (21). [3] The honeycomb structure forming tool (100, 300) according to claim 1 or 2, wherein the groove portion (31) is formed in the second mold (20). [4] Honeycomb structure forming tool (100, 300) according to one of claims 1 to 3, wherein a width of the groove portion (31) is from 0.1 to 1.5 mm. [5] The honeycomb structure forming tool (100, 300) according to any one of claims 1 to 4, wherein a depth of the grooves of the groove portion (31) is from 0.1 to 5.0 mm. [6] The honeycomb structure forming tool (100, 300) according to any one of claims 1 to 5, wherein a ratio of a total area of ​​the groove portion (31) and the open ends of the second kneading material introduction holes (22) in a region to an area in the region in which the groove portion (31) is formed in the abutting surface of the second mold (20) is from 40 to 90%. [7] Honeycomb structure forming tool (100, 300) according to one of claims 1 to 6, wherein a ratio of an area of ​​the central region (15) of the first mold (10) to an area of ​​an end face of a honeycomb molded body to be extruded is 30 to 70%. [8] Honeycomb structure forming tool (100, 300) according to one of claims 1 to 7, wherein grid slots surrounding a honeycomb (202) extend from the first grid slots (11) and grid slots surrounding a honeycomb (202) extend from the second grid slots (21) in mutually crossing directions. [9] The honeycomb structure forming tool (100, 300) according to any one of claims 1 to 8, wherein an arrangement direction of a honeycomb structure (200) of the honeycomb formed body to be extruded through the first lattice slots (11) and an arrangement direction of a honeycomb structure (200) of the honeycomb formed body to be extruded through the second lattice slots (21) extend in mutually crossing directions. [10] The honeycomb structure forming tool (100, 300) according to any one of claims 1 to 9, wherein in the first mold (10), the central region (15) is equal to the peripheral region (17) in terms of the opening diameter of the first kneading material introduction hole (12) and a distance between the first kneading material introduction holes (12). [11] The honeycomb structure forming tool (100, 300) according to any one of claims 1 to 10, wherein the honeycomb structure forming tool (100, 300) includes two or more second molds (20), the second mold (20) being replaceable, whereby a depth of the grooves of the groove portion (31) is changeable. [12] The honeycomb structure forming tool (100, 300) according to any one of claims 1 to 11, wherein the honeycomb structure forming tool (100, 300) includes two or more first molds (10), the first mold (10) being replaceable, whereby a depth of the grooves of the groove portion (31) is changeable.

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