JP2008023978A - Mouth piece for extrusion molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mouth piece for extrusion molding capable of moving raw material supplied from a supplying hole in a molding groove without stoppage. <P>SOLUTION: The mouth piece for extrusion molding comprises the molding grooves and a plurality of supplying holes communicating with the molding grooves, in which the bottom face form of the molding grooves which connect between the supplying holes is convexity in the extrusion direction of the raw material. The molding grooves have a top in the bottom of the central portion when showing from the longitudinally vertical section of grooves, in which the top is preferred having a tip and further preferred to be curved. Therefore, owing to the use of the mouth piece for extrusion molding, the raw material is extruded while smoothly spreading upward from the supplying holes, the underflow moves on the bottom face of the molding groove, and the raw material, which is made confluent in the vicinity of the top, is extruded upward without generating downward flow. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an extrusion die for extruding a honeycomb structure or the like, and suitable for manufacturing a ceramic honeycomb structure used for a catalyst carrier or a filter or a heat exchanger for exhaust gas purification. Regarding the base.

  Conventionally, as a die used for extrusion molding of a honeycomb structure, a supply hole into which clay is introduced is provided to be opened on one surface, and a molding groove corresponding to the cross-sectional shape of the honeycomb structure is opened on the other surface. There is known a structure in which the supply holes are provided in communication with each other at positions where the forming grooves intersect. In recent years, the partition walls of the honeycomb structure have become thinner, for example, 0.1 mm or less, and it has become difficult to stably produce a good honeycomb structure.

  For example, Japanese Patent Application Laid-Open No. 2003-11111 (Patent Document 1) proposes a mold (die) for forming a thin honeycomb structure without reducing the formability. As shown in FIG. 8, the mold in Patent Document 1 has a slit groove (molding groove) 82 formed so that a bottom portion 820 intersects with a side surface 810 of a supply hole 81, and a slit groove bottom portion 820 and a supply hole side surface 810. Inclined portions 85 are provided at the corners formed by the crossing, and in the inclined portions 85, there is a technical means that the depth of the slit groove 82 gradually increases as it approaches the supply hole 81. It is a thing. As a result, the material (kneaded material) that passes from the supply hole 81 to the slit groove 82 gradually spreads along the inclined portion 85, so that the material flow can be made smooth, and the molding pressure is reduced even in the narrow slit groove 82. An increase or the like can be suppressed, and excellent moldability can be maintained.

JP2003-11111 (paragraph number 0008)

  Patent Document 1 is an effective technique for obtaining an excellent honeycomb structure in that the flow of clay entering the forming groove from the supply hole is made smooth. However, when the forming groove becomes narrower, even if the clay is allowed to enter the forming groove smoothly from the supply hole, the flow of the clay changes if the flow resistance of the forming groove changes even slightly, Formability will be impaired. That is, even if the forming groove is well processed into a predetermined shape, if the floating foreign matter adheres to the side surface of the groove and the width of the groove is reduced or even part of the groove is clogged, the flow of the clay is obstructed. In some cases, the molded partition walls may be narrowed or chipped. In addition to the foreign matter mixed in from the outside, there are some that are generated from the clay itself. Since the latter foreign material is formed by separating and dispersing the clay that has stagnated and solidified in the forming groove, it is important to prevent the clay from stagnation. Is not mentioned at all.

  An object of the present invention is to provide an extrusion molding die capable of moving the clay supplied from the supply hole so as not to stagnate in the molding groove.

  The present inventor paid attention to the fact that the mold groove bottom surface of the mold of Patent Document 1 and the conventional mold cited in Patent Document 1 is a horizontal plane orthogonal to the supply hole side surface, and was supplied from the supply hole. We simulated the flow of the clay spread into the forming groove and pushed it, and confirmed that the clay on the horizontal bottom surface, especially the clay on the bottom surface near the center between the supply holes, was likely to stagnate. In the mold of Patent Document 1, an inclined portion is formed at the corner portion of the molding groove and is not a horizontal plane, but the bottom surface of the central portion is not changed to a horizontal plane, and the clay is easily stagnated here. This is because the clay pushed out from the supply hole is guided by the inclined portion and moves more strongly and obliquely upward, so if the inclination angle is steep and the central horizontal plane is large, the clay on the horizontal plane This is because the fluid force stops working.

The extrusion molding die according to the present invention is an extrusion molding die having a molding groove and a plurality of supply holes communicating with the molding groove, and the bottom shape of the molding groove connecting the supply holes is convex in the clay extrusion direction. It is characterized by being. The molding groove has a top portion at the center of the bottom surface when viewed in a longitudinal sectional view in the longitudinal direction of the groove, and the top portion preferably has a vertex, and more preferably has a curved shape. Therefore, when the extrusion molding die of the present invention is used, the clay is extruded while smoothly spreading upward from the supply hole, and its bottom flow moves on the bottom surface of the molding groove, and the clay that has joined near the top is downward. It is extruded upward without causing any flow. Moreover, the said shaping | molding groove | channel may have a top part in the center part of a bottom face, and a top part may have a horizontal surface below 0.2 mm. If the horizontal surface of the top is about this size, as the number of extrusion shots increases, the linear part wears and the top becomes curved and the apex is formed, and even during this time the clay remains large. It doesn't matter.
It is preferable that the top portion of the forming groove is at the same position as the front end portion of the side surface of the supply hole or at a position ahead thereof. In other words, the top height is preferably equal to or greater than the overlapping dimension of the forming groove and the supply hole, which is the distance from the position where the bottom surface of the forming groove intersects the side surface of the supply hole and the tip of the side surface of the supply hole. . Desirably, the size is 1 to 2 times.
In the extrusion molding die of the present invention, it is preferable that the supply holes are formed at every other position with respect to the intersection of the molding grooves. With such a die, it is possible to obtain a dense honeycomb structure with a finer partition wall pitch using supply holes of the same diameter, and it is possible to reduce the number of processing of the supply holes and reduce the manufacturing cost of the die. .

  According to the present invention, when the clay extruded from the supply hole spreads into the molding groove, the clay does not stagnate on the bottom surface of the molding groove, and the stagnated clay is separated from the molding groove. Generation | occurrence | production of the foreign material which may be formed can be prevented.

  Hereinafter, an extrusion forming die for forming a ceramic honeycomb structure having lattice-like square through holes will be described as an example.

  As shown in FIGS. 1 to 4, the extrusion molding die 10 of the first aspect of the present invention has a large number of supply holes on one surface (inflow side end surface) 7 of the die base 1 on the side into which the ceramic clay flows. 2 is formed, forming grooves 3 are formed at substantially the same vertical and horizontal pitches on the other surface (outlet side end surface) 8 from which the ceramic clay flows out, and the supply holes 2 and the forming grooves 3 are formed inside the base 1. It is a connected structure. The ceramic clay introduced from the supply hole 2 moves to the forming groove 3 through the communication portion 4, and the clay from the adjacent supply hole joins in the forming groove, whereby the honeycomb structure is formed. FIG. 1 is a longitudinal sectional view when the forming groove 3 is cut along a surface along the longitudinal direction of the groove between the two supply holes 2a and 2b. FIG. 2 is a view of the inflow side end face 7 side where the supply hole 2 is opened. FIG. 3 is a plan view of the outflow side end face 8 side where the forming groove 3 is opened, and FIG. 4 is a longitudinal sectional view along the line XX in FIG. 3 showing the relationship between the supply hole 2 and the forming groove 3. It is. In the extrusion molding die 10 in the present description, the supply holes 2 are formed in a staggered pattern at every other position with respect to the intersections of the molding grooves 3. As the material of the base 1, known materials such as mechanical structural steel and tool steel can be used.

  The bottom surface 3a of the forming groove 3 is convex in the clay extrusion direction. Specifically, as shown in FIG. 1, a substantially bilaterally symmetric shape that continuously increases from the intersections 3 c, 3 d toward the top 3 b with the side surface of the left supply hole 2 a and the side surface of the right supply hole 2 b. The top portion 3b is a curve that bulges outward. The shape of FIG. 1 is an example in which the ridgeline is triangular, but it can also be a shape as shown in FIG. 5 (a) is an example of a sinusoidal shape, FIG. 5 (b) is an example of an arc shape and the ridge line bulges outward, and FIG. 5 (c) is an example of a ripple shape and the ridge line is dented inward. It is good also as a combined shape. In any shape, it is desirable that the apex 3b, specifically the apex of the apex, be a curve that is convex outward and has an apex.

  The forming groove 3 is formed with a predetermined depth D so as to overlap the supply hole 2 with a predetermined dimension h. The depth D of the forming groove 3 is a distance between the outflow side end surface 8 and the intersecting portions 3c and 3d. The intersecting portions 3c and 3d are lower than the front end portions of the side surfaces of the supply holes 2a and 2b by a predetermined dimension h in FIG. It is formed to be located. The top portion 3b is formed at a substantially central portion between the left and right supply holes 2a and 2b, and the bottom flow of the clay supplied from the left and right supply holes 2a and 2b and extruded into the forming groove 3 is joined at the central portion of the forming groove. The height t is such that it can move along the bottom surface 3a of the molding groove 3 until it is. The height t is preferably large and is preferably not less than the overlap dimension h. As described above, it is desirable that the top portion 3b has an outwardly convex curve. However, in consideration of workability and tools at the time of forming the forming groove 3, left and right supply holes are provided as shown in FIG. The ridgelines from the left may be kept intersecting, or may have a minute linear horizontal plane as shown in FIG. At this time, the horizontal plane preferably has a groove direction length s of 0.2 mm or less. With this size, the clay hardly stays on the horizontal plane, and as the number of extrusion shots proceeds, the linear portion wears out and becomes a curved shape, and a top portion is formed.

A method for manufacturing the extrusion die 10 will be described.
First, a plate-shaped base 1 made by machining tool steel to a predetermined size is prepared, and a predetermined number of supply holes 2 are processed in a vertical and horizontal direction at a predetermined depth from the inflow side end face 7 side of the base 1. As the hole machining method, a drilling method, an electric discharge machining method using an electrode, or the like can be applied. Next, the forming groove 3 is processed so as to intersect vertically and horizontally from the outflow side end face 8 side of the die base 1. The supply hole 2 is formed at every other position with respect to the intersection of the forming grooves 3. The groove machining method is performed by electric discharge machining using an electrode. As shown in FIG. 7, the electrode 9 has an elongated plate shape, and the bottom portion 9a is formed with a large number of similar shapes having a sex relationship with the shape of the bottom surface 3a of the forming groove. be able to. As described above, the position and processing time of the electrode 9 are appropriately controlled so that the overlapping dimension of the forming groove 3 and the supply hole 2 is h.

  As described above, when extrusion molding is performed using the extrusion molding die 10 of the present invention, the clay is extruded while smoothly spreading upward from the supply hole 2, and the bottom flow is formed on the bottom surface 3a of the molding groove. The clay that has moved and merged in the vicinity of the top 3b is pushed upward without causing a downward flow. Therefore, the clay does not stay in the molding groove 3 and does not solidify and become foreign matter. As a result, foreign matter formed from the clay does not adhere to the side surface of the molding groove 3 to disturb the flow of the clay, or block a part of the molding groove 3 to obstruct the flow of the clay. Therefore, the partition walls of the extruded honeycomb structure are densely formed with a predetermined width. In addition, since the foreign matter is not mixed in the clay and embedded in the honeycomb structure, the foreign matter does not drop off in the subsequent process and the partition wall is not damaged.

  As can be seen from the above description, the extrusion molding die 10 of the present invention is more effective than the case where the length of the molding groove 3 connecting between the supply holes 2 is long. In this respect, the present invention works extremely effectively when applied to a base in which the supply holes are formed at every other position or more than the intersection of the forming grooves. Such a die can obtain a dense honeycomb structure with a finer partition wall pitch using the supply holes 2 having the same diameter, and can reduce the number of processing of the supply holes 2 to reduce the manufacturing cost of the die. Has the advantage of being able to In this respect, it may be applied as a die for a hexagonal honeycomb structure like the die for extrusion molding according to the second aspect described below. Needless to say, the present invention may be applied to the case where the supply holes 2 are formed at all the positions where the forming grooves 3 intersect, and it is effective when used for forming a honeycomb structure having a large partition wall pitch.

(Example)
Six types of samples having different top heights t as shown in the following Table 1 on the triangular bottom as shown in FIG. In each sample, the thickness of the substrate is 20 mm, the formed groove has a vertical and horizontal pitch of 1 mm, the width is 0.1 mm, the depth D is 3 mm, the supply hole has a diameter of 1 mm, and the depth is 17.5 mm. It formed in every other position with respect to the intersection. Accordingly, the overlap dimension h between the forming groove and the supply hole is 0.5 mm in any sample. Martensitic stainless steel tool steel (made by Hitachi Metals, stainless steel prehardened steel for plastic molds, HPM38) is used as the base, the supply hole is machined with a carbide drill in the prehardened state of hardness HRC33, and the forming groove is machined by electric discharge machining. did. Samples having different top heights t were manufactured using the electrodes shown in FIG. 7 having different triangular dimensions. Thereafter, it was immersed in an electroless Ni—P plating solution, and a surface of a plating film of about 10 μm was coated, followed by heat treatment at 400 ° C. The hardness of the plated film after the heat treatment was 950 at about HV.

Six types of samples (samples 1 to 6) having different top heights t manufactured as described above were used, and honeycomb molded bodies were actually extrusion molded using raw materials having a cordierite composition. In addition, the raw material used the thing which adjusted the water | moisture content compared with the normal thing, and made it easy to aggregate by making a viscosity about 2 times.
First, 100 honeycomb formed bodies were extruded. The partition walls on both end faces of 100 molded bodies were visually observed. Sample 1 is equivalent to a conventional molding groove whose bottom surface is a horizontal surface, and there were no defective parts, but there were three cases where a slightly constricted partition wall was formed on the end face on the extrusion head side. Two cell intersections that appear to be uneven in particle size were confirmed. Neither sample 2 nor defective product was found, but a few constricted partition walls were formed on the end face on the extrusion head side. Samples 3 and 4 were all good and passed. Although the sample 5 was not defective, it was found that a slightly constricted partition wall was formed on the end face on the extrusion head side. In the sample 6, the molding of the partition wall intersection was poor.

  Furthermore, each sample was subjected to continuous molding for 20 hours, and then the raw material in the molding groove as viewed from the outflow side was observed to check for the presence of aggregates. This confirmation was made by shining strong light from the outflow side and looking through a magnifier. If there is agglomerated foreign matter, it looks white. The fact that foreign matter is seen in the raw material in the molding groove means that the raw material is stagnant in the molding groove and foreign matter is generated, but it cannot be observed unless it is mixed and extruded into the raw material during molding. Even if foreign matter is generated, it may not be observed. In this experiment, a foreign matter of 0.01 mm or less was confirmed in Sample 2, but not in other samples.

  The above results are summarized in Table 1. Formability, including confirmation of foreign matter, deteriorated compared to the conventional case where the bottom of the forming groove is horizontal (t = 0), ◯ for good, ◎ for particularly good, △ for similar What was done was evaluated as x.

  From the above, as shown in Samples 2 to 5, a mold that can form a molded body, and a mold having a top portion formed on the bottom surface of the molding groove is formable as compared with a mold having a horizontal groove bottom surface. Was confirmed to improve. As shown in Samples 3 and 4, the top height t of the bottom surface of the forming groove is in the range of not less than twice the overlapping dimension h of the forming groove and the supply hole, i.e. It is particularly effective when it is formed at the same position or at a position that is approximately twice as long as the overlap dimension, and even when the amount of moisture in the raw material fluctuates and the viscosity increases, the raw material is compressed and agglomerated. It can be seen that a fine honeycomb structure can be extruded without being extruded from the forming groove.

  The extrusion molding die according to the second aspect of the present invention will be described with reference to FIGS. In addition, in FIGS. 9-11, about the same component as the die for extrusion molding of the said 1st aspect, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. Further, the entire structure of the extrusion molding die of the second aspect is substantially the same as that of the extrusion molding die of the first aspect, and therefore will be described with reference to FIGS.

  As shown in FIG. 10, in the extrusion molding die 20 of the second embodiment, the hexagonal molding grooves 32 are repeatedly arranged in a plan view when viewed from the outflow side end face 8 side. Thus, by making the shape of the forming groove 32 hexagonal, the formability can be further improved as compared with the extrusion die 10 having the grid-like forming groove 3. This is because, in the case of a grid pattern, the forming groove 3 is attached to one supply hole 2 and extends in all directions, whereas in the case of a hexagon, there is a forming groove 32 in only three directions in one supply hole 2. . Further, by forming the forming groove 32 in a hexagonal shape, the extruded honeycomb structure has a configuration in which hexagonal holes are densely arranged, and an original honeycomb structure can be realized.

  The supply holes 2 are processed at every other apex of the hexagonal shaped grooves 32, and are arranged in a staggered pattern when viewed from the inflow side end face 7.

  As shown in FIG. 10, the configuration of the bottom surface 32a of the molding groove 32 is the same as that of the molding groove 3 of the extrusion molding die 10 of the first aspect. That is, the bottom surface 32a of the forming groove 32 is convex in the clay extrusion direction. Specifically, as shown in FIG. 9, which is an XX arrow view in FIG. 10, the intersections 32 c and 32 d with the side surface of the left supply hole 2 a and the side surface of the right supply hole 2 b face the top portion 32 b. The top 32b is a curved curve that swells outward.

  The manufacturing method of the extrusion molding die 20 is the same as that of the extrusion molding die 10 except that the electrode for electric discharge machining for forming the molding groove 32 is different. That is, the shape in plan view of the electrode 92 for processing the forming groove 32 of the extrusion forming die 20 is formed corresponding to a meandering series of forming grooves 32 having a hexagonal shape as shown in FIG. ing. 11A, the bottom 32a of the molding groove 32 and the bottom surface 92a of the electrode 92 have a male-female relationship.

(Example)
Three types of samples having different top heights t as shown in Table 2 below on the triangular bottom as shown in FIG. In all samples, the thickness of the substrate is 20 mm, the forming groove 32 has a hexagonal side of 1 mm, the width is 0.1 mm, the depth D is 3 mm, the supply hole has a diameter of 1 mm, and the depth is 17.5 mm. It was formed at every other position with respect to the hexagonal apex. Accordingly, the overlap dimension h between the forming groove and the supply hole is 0.5 mm in any sample. Martensitic stainless alloy tool steel (made by Hitachi Metals, stainless steel prehardened steel for plastic molds, HPM38) is used as the substrate, the supply hole is machined with a carbide drill in the prehardened state with hardness HRC33, and the forming groove is machined by electric discharge machining. did. Samples with different top heights t were manufactured using the electrodes shown in FIG. 11 with different triangular dimensions. Thereafter, it was immersed in an electroless Ni—P plating solution, and a surface of a plating film of about 10 μm was coated, followed by heat treatment at 400 ° C. The hardness of the plated film after the heat treatment was 950 at about HV.

  Three types of samples (samples 7 to 9) having different top heights t manufactured as described above were used, and honeycomb molded bodies were actually extruded using raw materials having a cordierite composition. In addition, the raw material used the thing which adjusted the water | moisture content compared with the normal thing, and made it easy to aggregate by making a viscosity about 2 times.

  First, 100 honeycomb formed bodies were extruded. The partition walls on both end faces of 100 molded bodies were visually observed. Specimen 7 corresponds to a conventional molding groove whose groove bottom surface is horizontal, and what should be considered as a defective product was not seen, but there were two things in which a slightly constricted partition wall was formed on the end face of the extrusion head side. Two cell intersections that appear to be uneven in particle size were confirmed. All samples 8 were good and passed. The sample 9 was not defective, but a small constricted partition wall was formed on the end face on the extrusion head side.

  The above results are summarized in Table 2. The moldability including confirmation of foreign matters was compared according to the degree of undulation on the bottom surface of the forming groove, and a good one was evaluated as ○, a particularly good one as ◎, and a deteriorated one as ×.

  From the above, as shown in Samples 8 and 9, also in the extrusion molding die 20 of the second embodiment, the mold having the top portion formed on the bottom surface of the molding groove is molded as compared with the mold having a horizontal groove bottom surface. It was confirmed that the property was improved.

It is a longitudinal cross-sectional view which shows the example of the bottom face shape of the shaping | molding groove | channel of the die for extrusion molding of the 1st aspect concerning this invention. FIG. 2 is a plan view of an inflow side end face side in which a supply hole of a die base of the extrusion molding die of FIG. 1 is opened. FIG. 2 is a plan view on the outflow side end face side in which a forming groove of a die base of the die for extrusion molding in FIG. 1 is opened. It is sectional drawing along the XX line of FIG. 3, and is a figure which shows the relationship between a supply hole and a shaping | molding groove | channel. It is a longitudinal cross-sectional view which shows the other example of the bottom face shape of the shaping | molding groove | channel concerning this invention. It is a longitudinal cross-sectional view for demonstrating the horizontal surface of the top part of a shaping | molding groove bottom face. It is a figure which shows the example of the electrode for electrical discharge machining for the shaping | molding groove processing of FIG. It is a figure which shows the bottom face shape of the shaping | molding groove | channel disclosed by patent document 1 as a prior art. It is a longitudinal cross-sectional view which shows the example of the bottom face shape of the shaping | molding groove | channel of the die for extrusion molding of the 2nd aspect concerning this invention. FIG. 10 is a partially enlarged plan view of the inflow side end face side where the supply hole of the die base of the extrusion molding die of FIG. 9 is opened. It is a figure which shows the example of the electrode for electrical discharge machining for the shaping | molding groove processing of FIG.

Explanation of symbols

10 (20): base for extrusion molding, 1: base material for base, 2 (81): supply hole, 3 (32, 82): molding groove,
3a (32a): forming groove bottom surface, 3b (32b): forming groove top, 3c (32c), 3d (32d): intersecting part, 4: communicating part,
9 (92): Electrodischarge machining electrode,
t: forming groove bottom height (top height), h: overlapping dimension of forming groove and supply hole

Claims (5)

For extrusion molding die having a molding groove and a plurality of supply holes communicating with the molding groove, the shape of the bottom surface of the molding groove connecting the supply holes is convex in the clay extrusion direction. Base. The die for extrusion molding according to claim 1, wherein the molding groove has a top portion at the center of the bottom surface, and the top portion has a top. The extrusion molding die according to claim 1, wherein the forming groove has a top portion at a center portion of the bottom surface, and the top portion has a horizontal surface whose length in the groove direction is 0.2 mm or less. The extrusion molding die according to any one of claims 1 to 3, wherein a top portion of the molding groove is located at a position that is the same as or farther from the front end portion of the side surface of the supply hole. 5. The die for extrusion molding according to claim 1, wherein the supply holes are formed at every other position with respect to the intersections of the molding grooves.

Images